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Springer E, Heimsch KC, Rahlfs S, Becker K, Przyborski JM. Real-time measurements of ATP dynamics via ATeams in Plasmodium falciparum reveal drug-class-specific response patterns. Antimicrob Agents Chemother 2024; 68:e0169023. [PMID: 38501806 PMCID: PMC11064498 DOI: 10.1128/aac.01690-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 02/26/2024] [Indexed: 03/20/2024] Open
Abstract
Malaria tropica, caused by the parasite Plasmodium falciparum (P. falciparum), remains one of the greatest public health burdens for humankind. Due to its pivotal role in parasite survival, the energy metabolism of P. falciparum is an interesting target for drug design. To this end, analysis of the central metabolite adenosine triphosphate (ATP) is of great interest. So far, only cell-disruptive or intensiometric ATP assays have been available in this system, with various drawbacks for mechanistic interpretation and partly inconsistent results. To address this, we have established fluorescent probes, based on Förster resonance energy transfer (FRET) and known as ATeam, for use in blood-stage parasites. ATeams are capable of measuring MgATP2- levels in a ratiometric manner, thereby facilitating in cellulo measurements of ATP dynamics in real-time using fluorescence microscopy and plate reader detection and overcoming many of the obstacles of established ATP analysis methods. Additionally, we established a superfolder variant of the ratiometric pH sensor pHluorin (sfpHluorin) in P. falciparum to monitor pH homeostasis and control for pH fluctuations, which may affect ATeam measurements. We characterized recombinant ATeam and sfpHluorin protein in vitro and stably integrated the sensors into the genome of the P. falciparum NF54attB cell line. Using these new tools, we found distinct sensor response patterns caused by several different drug classes. Arylamino alcohols increased and redox cyclers decreased ATP; doxycycline caused first-cycle cytosol alkalization; and 4-aminoquinolines caused aberrant proteolysis. Our results open up a completely new perspective on drugs' mode of action, with possible implications for target identification and drug development.
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Affiliation(s)
- Eric Springer
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, Giessen, Germany
| | - Kim C. Heimsch
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, Giessen, Germany
| | - Stefan Rahlfs
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, Giessen, Germany
| | - Katja Becker
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, Giessen, Germany
| | - Jude M. Przyborski
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, Giessen, Germany
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2
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Pavić K, Poje G, Pessanha de Carvalho L, Tandarić T, Marinović M, Fontinha D, Held J, Prudêncio M, Piantanida I, Vianello R, Krošl Knežević I, Perković I, Rajić Z. Discovery of harmiprims, harmine-primaquine hybrids, as potent and selective anticancer and antimalarial compounds. Bioorg Med Chem 2024; 105:117734. [PMID: 38677112 DOI: 10.1016/j.bmc.2024.117734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Revised: 04/18/2024] [Accepted: 04/18/2024] [Indexed: 04/29/2024]
Abstract
Although cancer and malaria are not etiologically nor pathophysiologically connected, due to their similarities successful repurposing of antimalarial drugs for cancer and vice-versa is known and used in clinical settings and drug research and discovery. With the growing resistance of cancer cells and Plasmodium to the known drugs, there is an urgent need to discover new chemotypes and enrich anticancer and antimalarial drug portfolios. In this paper, we present the design and synthesis of harmiprims, hybrids composed of harmine, an alkaloid of the β-carboline type bearing anticancer and antiplasmodial activities, and primaquine, 8-aminoquinoline antimalarial drug with low antiproliferative activity, covalently bound via triazole or urea. Evaluation of their antiproliferative activities in vitro revealed that N-9 substituted triazole-type harmiprime was the most selective compound against MCF-7, whereas C1-substituted ureido-type hybrid was the most active compound against all cell lines tested. On the other hand, dimeric harmiprime was not toxic at all. Although spectrophotometric studies and thermal denaturation experiments indicated binding of harmiprims to the ds-DNA groove, cell localization showed that harmiprims do not enter cell nucleus nor mitochondria, thus no inhibition of DNA-related processes can be expected. Cell cycle analysis revealed that C1-substituted ureido-type hybrid induced a G1 arrest and reduced the number of cells in the S phase after 24 h, persisting at 48 h, albeit with a less significant increase in G1, possibly due to adaptive cellular responses. In contrast, N-9 substituted triazole-type harmiprime exhibited less pronounced effects on the cell cycle, particularly after 48 h, which is consistent with its moderate activity against the MCF-7 cell line. On the other hand, screening of their antiplasmodial activities against the erythrocytic, hepatic, and gametocytic stages of the Plasmodium life cycle showed that dimeric harmiprime exerts powerful triple-stage antiplasmodial activity, while computational analysis showed its binding within the ATP binding site of PfHsp90.
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Affiliation(s)
- Kristina Pavić
- University of Zagreb Faculty of Pharmacy and Biochemistry, A. Kovačića 1, 10000 Zagreb, Croatia.
| | - Goran Poje
- University of Zagreb Faculty of Pharmacy and Biochemistry, A. Kovačića 1, 10000 Zagreb, Croatia
| | | | - Tana Tandarić
- Department of Cell and Molecular Biology, Uppsala University, 75124 Uppsala, Sweden; Rudjer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Marina Marinović
- University of Zagreb Faculty of Pharmacy and Biochemistry, A. Kovačića 1, 10000 Zagreb, Croatia
| | - Diana Fontinha
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisboa, Portugal
| | - Jana Held
- University of Tübingen, Institute of Tropical Medicine, Wilhelmstraße 27, 72074 Tübingen, Germany; German Center for Infection Research, Partner Site Tübingen, Tübingen, Germany
| | - Miguel Prudêncio
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisboa, Portugal
| | - Ivo Piantanida
- Rudjer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Robert Vianello
- Rudjer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | | | - Ivana Perković
- University of Zagreb Faculty of Pharmacy and Biochemistry, A. Kovačića 1, 10000 Zagreb, Croatia
| | - Zrinka Rajić
- University of Zagreb Faculty of Pharmacy and Biochemistry, A. Kovačića 1, 10000 Zagreb, Croatia.
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3
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Platon L, Ménard D. Plasmodium falciparum ring-stage plasticity and drug resistance. Trends Parasitol 2024; 40:118-130. [PMID: 38104024 DOI: 10.1016/j.pt.2023.11.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 11/15/2023] [Accepted: 11/15/2023] [Indexed: 12/19/2023]
Abstract
Malaria is a life-threatening tropical disease caused by parasites of the genus Plasmodium, of which Plasmodium falciparum is the most lethal. Malaria parasites have a complex life cycle, with stages occurring in both the Anopheles mosquito vector and human host. Ring stages are the youngest form of the parasite in the intraerythrocytic developmental cycle and are associated with evasion of spleen clearance, temporary growth arrest (TGA), and drug resistance. This formidable ability to survive and develop into mature, sexual, or growth-arrested forms demonstrates the inherent population heterogeneity. Here we highlight the role of the ring stage as a crossroads in parasite development and as a reservoir of surviving cells in the human host via TGA survival mechanisms.
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Affiliation(s)
- Lucien Platon
- Institut Pasteur, Université Paris Cité, Malaria Genetics and Resistance Unit, INSERM U1201, F-75015 Paris, France; Sorbonne Université, Collège Doctoral ED 515 Complexité du Vivant, F-75015 Paris, France; Université de Strasbourg, Institute of Parasitology and Tropical Diseases, UR7292 Dynamics of Host-Pathogen Interactions, F-67000 Strasbourg, France.
| | - Didier Ménard
- Institut Pasteur, Université Paris Cité, Malaria Genetics and Resistance Unit, INSERM U1201, F-75015 Paris, France; Institut Pasteur, Université Paris Cité, Malaria Parasite Biology and Vaccines Unit, F-75015 Paris, France; Université de Strasbourg, Institute of Parasitology and Tropical Diseases, UR7292 Dynamics of Host-Pathogen Interactions, F-67000 Strasbourg, France; CHU Strasbourg, Laboratory of Parasitology and Medical Mycology, F-67000 Strasbourg, France.
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4
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Maciuk A, Mazier D, Duval R. Future antimalarials from Artemisia? A rationale for natural product mining against drug-refractory Plasmodium stages. Nat Prod Rep 2023; 40:1130-1144. [PMID: 37021639 DOI: 10.1039/d3np00001j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023]
Abstract
Covering: up to 2023Infusions of the plants Artemisia annua and A. afra are gaining broad popularity to prevent or treat malaria. There is an urgent need to address this controversial public health question by providing solid scientific evidence in relation to these uses. Infusions of either species were shown to inhibit the asexual blood stages, the liver stages including the hypnozoites, but also the sexual stages, the gametocytes, of Plasmodium parasites. Elimination of hypnozoites and sterilization of mature gametocytes remain pivotal elements of the radical cure of P. vivax, and the blockage of P. vivax and P. falciparum transmission, respectively. Drugs active against these stages are restricted to the 8-aminoquinolines primaquine and tafenoquine, a paucity worsened by their double dependence on the host genetic to elicit clinical activity without severe toxicity. Besides artemisinin, these Artemisia spp. contain many natural products effective against Plasmodium asexual blood stages, but their activity against hypnozoites and gametocytes was never investigated. In the context of important therapeutic issues, we provide a review addressing (i) the role of artemisinin in the bioactivity of these Artemisia infusions against specific parasite stages, i.e., alone or in association with other phytochemicals; (ii) the mechanisms of action and biological targets in Plasmodium of ca. 60 infusion-specific Artemisia phytochemicals, with an emphasis on drug-refractory parasite stages (i.e., hypnozoites and gametocytes). Our objective is to guide the strategic prospecting of antiplasmodial natural products from these Artemisia spp., paving the way toward novel antimalarial "hit" compounds either naturally occurring or Artemisia-inspired.
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Affiliation(s)
| | - Dominique Mazier
- CIMI, CNRS, Inserm, Faculté de Médecine Sorbonne Université, 75013 Paris, France
| | - Romain Duval
- MERIT, IRD, Université Paris Cité, 75006 Paris, France.
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Dinko B, Awuah D, Boampong K, Larbi JA, Bousema T, Sutherland CJ. Prevalence of Plasmodium falciparum gametocytaemia in asymptomatic school children before and after treatment with dihydroartemisinin-piperaquine (DP). Parasite Epidemiol Control 2023; 21:e00292. [PMID: 36860282 PMCID: PMC9969054 DOI: 10.1016/j.parepi.2023.e00292] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 01/12/2023] [Accepted: 02/15/2023] [Indexed: 02/19/2023] Open
Abstract
Background Asymptomatic Plasmodium carriers form the majority of malaria-infected individuals in most endemic areas. A proportion of these asymptomatically infected individuals carry gametocytes, the transmissible stages of malaria parasites, that sustain human to mosquito transmission. Few studies examine gametocytaemia in asymptomatic school children who may form an important reservoir for transmission. We assessed the prevalence of gametocytaemia before antimalarial treatment and monitored clearance of gametocytes after treatment in asymptomatic malaria children. Methods A total of 274 primary school children were screened for P. falciparum parasitaemia by microscopy. One hundred and fifty-five (155) parasite positive children were treated under direct observation with dihydroartemisinin-piperaquine (DP). Gametocyte carriage was determined by microscopy seven days prior to treatment, day 0 before treatment, and on days 7, 14 and 21 post initiation of treatment. Results The prevalence of microscopically-detectable gametocytes at screening (day -7) and enrolment (day 0) were 9% (25/274) and 13.6% (21/155) respectively. Following DP treatment, gametocyte carriage dropped to 4% (6/135), 3% (5/135) and 6% (10/151) on days 7, 14 and 21 respectively. Asexual parasites persisted in a minority of treated children, resulting in microscopically detectable parasites on days 7 (9%, 12/135), 14 (4%, 5/135) and 21 (7%, 10/151). Gametocyte carriage was inversely correlated with the age of the participants (p = 0.05) and asexual parasite density (p = 0.08). In a variate analysis, persistent gametocytaemia 7 or more days after treatment was significantly associated with post-treatment asexual parasitaemia at day 7 (P = 0.027) and presence of gametocytes on the day of treatment (P < 0.001). Conclusions Though DP provides both excellent cure rates for clinical malaria and a long prophylactic half-life, our findings suggest that after treatment of asymptomatic infections, both asexual parasites and gametocytes may persist in a minority of individuals during the first 3 weeks after treatment. This indicates DP may be unsuitable for use in mass drug administration strategies towards malaria elimination in Africa.
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Affiliation(s)
- Bismarck Dinko
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Dennis Awuah
- Department of Theoretical and Applied Biology, Faculty of Biosciences, College of Science, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Kwadwo Boampong
- Department of Theoretical and Applied Biology, Faculty of Biosciences, College of Science, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - John A. Larbi
- Department of Theoretical and Applied Biology, Faculty of Biosciences, College of Science, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Teun Bousema
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
- Department of Medical Microbiology, Nijmegen Medical Centre, Radboud University, Nijmegen, the Netherlands
| | - Colin J. Sutherland
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
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Istvan ES, Guerra F, Abraham M, Huang KS, Rocamora F, Zhao H, Xu L, Pasaje C, Kumpornsin K, Luth MR, Cui H, Yang T, Diaz SP, Gomez-Lorenzo MG, Qahash T, Mittal N, Ottilie S, Niles J, Lee MCS, Llinas M, Kato N, Okombo J, Fidock DA, Schimmel P, Gamo FJ, Goldberg DE, Winzeler EA. Cytoplasmic isoleucyl tRNA synthetase as an attractive multistage antimalarial drug target. Sci Transl Med 2023; 15:eadc9249. [PMID: 36888694 PMCID: PMC10286833 DOI: 10.1126/scitranslmed.adc9249] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 02/17/2023] [Indexed: 03/10/2023]
Abstract
Development of antimalarial compounds into clinical candidates remains costly and arduous without detailed knowledge of the target. As resistance increases and treatment options at various stages of disease are limited, it is critical to identify multistage drug targets that are readily interrogated in biochemical assays. Whole-genome sequencing of 18 parasite clones evolved using thienopyrimidine compounds with submicromolar, rapid-killing, pan-life cycle antiparasitic activity showed that all had acquired mutations in the P. falciparum cytoplasmic isoleucyl tRNA synthetase (cIRS). Engineering two of the mutations into drug-naïve parasites recapitulated the resistance phenotype, and parasites with conditional knockdowns of cIRS became hypersensitive to two thienopyrimidines. Purified recombinant P. vivax cIRS inhibition, cross-resistance, and biochemical assays indicated a noncompetitive, allosteric binding site that is distinct from that of known cIRS inhibitors mupirocin and reveromycin A. Our data show that Plasmodium cIRS is an important chemically and genetically validated target for next-generation medicines for malaria.
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Affiliation(s)
- Eva S. Istvan
- Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63130, USA
| | - Francisco Guerra
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, USA
| | - Matthew Abraham
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, USA
| | | | - Frances Rocamora
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, USA
| | | | - Lan Xu
- The Global Health Drug Discovery Institute, Tsinghua University 30 Shuangqing Rd, Haidian District, Beijing, China
| | - Charisse Pasaje
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | | | - Madeline R. Luth
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, USA
| | - Haissi Cui
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Tuo Yang
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, USA
| | - Sara Palomo Diaz
- Global Health Medicines, GlaxoSmithKline, Severo Ochoa 2, 28760 Tres Cantos, Spain
| | | | - Tarrick Qahash
- Department of Biochemistry & Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
- Huck Center for Malaria Research, Pennsylvania State University, University Park, PA 16802, USA
| | - Nimisha Mittal
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, USA
| | - Sabine Ottilie
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, USA
| | - Jacquin Niles
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Marcus C. S. Lee
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, CB10 1SA, UK
| | - Manuel Llinas
- Department of Biochemistry & Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
- Huck Center for Malaria Research, Pennsylvania State University, University Park, PA 16802, USA
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA
| | - Nobutaka Kato
- The Global Health Drug Discovery Institute, Tsinghua University 30 Shuangqing Rd, Haidian District, Beijing, China
| | - John Okombo
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, New York 10032, USA
| | - David A. Fidock
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, New York 10032, USA
- Center for Malaria Therapeutics and Antimicrobial Resistance, Division of Infectious Diseases, Department of Medicine, Columbia University Irving Medical Center, New York, New York 10032, USA
| | - Paul Schimmel
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | | | - Daniel E. Goldberg
- Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63130, USA
| | - Elizabeth A. Winzeler
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, USA
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7
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Omorou R, Bin Sa'id I, Delves M, Severini C, Kouakou YI, Bienvenu AL, Picot S. Protocols for Plasmodium gametocyte production in vitro: an integrative review and analysis. Parasit Vectors 2022; 15:451. [PMID: 36471426 PMCID: PMC9720971 DOI: 10.1186/s13071-022-05566-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 11/02/2022] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND The production of Plasmodium gametocytes in vitro is a real challenge. Many protocols have been described, but few have resulted in the production of viable and infectious gametocytes in sufficient quantities to conduct research on-but not limited to-transmission-blocking drug and vaccine development. The aim of this review was to identify and discuss gametocyte production protocols that have been developed over the last two decades. METHODS We analyzed the original gametocyte production protocols published from 2000 onwards based on a literature search and a thorough review. A systematic review was performed of relevant articles identified in the PubMed, Web of Sciences and ScienceDirect databases. RESULTS A total 23 studies on the production of Plasmodium gametocytes were identified, 19 involving in vitro Plasmodium falciparum, one involving Plasmodium knowlesi and three involving ex vivo Plasmodium vivax. Of the in vitro studies, 90% used environmental stressors to trigger gametocytogenesis. Mature gametocytemia of up to 4% was reported. CONCLUSIONS Several biological parameters contribute to an optimal production in vitro of viable and infectious mature gametocytes. The knowledge gained from this systematic review on the molecular mechanisms involved in gametocytogenesis enables reproducible gametocyte protocols with transgenic parasite lines to be set up. This review highlights the need for additional gametocyte production protocols for Plasmodium species other than P. falciparum.
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Affiliation(s)
- Roukayatou Omorou
- Malaria Research Unit, UMR 5246 CNRS-INSA-CPE-University Lyon1, University of Lyon, 69100, Villeurbanne, France.
| | - Ibrahim Bin Sa'id
- Malaria Research Unit, UMR 5246 CNRS-INSA-CPE-University Lyon1, University of Lyon, 69100, Villeurbanne, France.,Institut Agama Islam Negeri (IAIN) Kediri, 64127, Kota Kediri, Jawa Timur, Indonesia
| | - Michael Delves
- Department of Infection Biology, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1A 7HT, UK
| | - Carlo Severini
- Dipartimento Di Malattie Infettive, Istituto Superiore Di Sanità, Rome, Italy
| | - Yobouet Ines Kouakou
- Malaria Research Unit, UMR 5246 CNRS-INSA-CPE-University Lyon1, University of Lyon, 69100, Villeurbanne, France
| | - Anne-Lise Bienvenu
- Malaria Research Unit, UMR 5246 CNRS-INSA-CPE-University Lyon1, University of Lyon, 69100, Villeurbanne, France.,Service Pharmacie, Groupement Hospitalier Nord, Hospices Civils de Lyon, Lyon, France
| | - Stephane Picot
- Malaria Research Unit, UMR 5246 CNRS-INSA-CPE-University Lyon1, University of Lyon, 69100, Villeurbanne, France.,Institut de Parasitologie Et Mycologie Médicale, Groupement Hospitalier Nord, Hospices Civils de Lyon, Lyon, France
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8
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Rakotoarisoa MA, Fenomanana J, Dodoson BT, Andrianaranjaka VHI, Ratsimbasoa A. Comparative effect of artemether-lumefantrine and artesunate-amodiaquine on gametocyte clearance in children with uncomplicated Plasmodium falciparum malaria in Madagascar. Malar J 2022; 21:331. [PMID: 36376921 PMCID: PMC9664793 DOI: 10.1186/s12936-022-04369-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 11/05/2022] [Indexed: 11/16/2022] Open
Abstract
Background Gametocytes are the sexual stages ensuring continuity of the development cycle of the parasite, as well as its transmission to humans. The efficacy of artemisinin-based anti-malarials against asexual stages of Plasmodium has been reported in Madagascar, but their effects on gametocytes are not well documented. The present study aims to determine the emergence of gametocyte and gametocyte clearance after artesunate-amodiaquine (ASAQ) or artemether-lumefantrine (AL) treatment in children with uncomplicated Plasmodium falciparum malaria in 5 regions of Madagascar. Methods 558 children with uncomplicated P. falciparum malaria, aged between 1 and 15 years, were assigned randomly to AL or ASAQ treatment. They come from 5 regions of Madagascar with different epidemiological facies related to malaria: Ankilivalo, Benenitra, Ampanihy, Ankazomborona and Matanga. Gametocytes were identified by microscopy, from t blood smears at day 1, day 2, day 3, day 7, day 14, day 21 and day 28 after treatment. Results At baseline, 9.7% (54/558) children [95% CI: 7.4–12.5%] had detectable gametocyte by microscopy. Among the 54 enrolled children, gametocytes emergence rate was high during the first days of treatment in both treatment arms (AL and ASAQ), especially on day 1. Gametocytes were undetectable from day 14 for AL arm while for ASAQ arm, gametocyte carriage was gradually decreased but persisted until day 21. Conclusion This study demonstrates that AL has a more rapid effect on gametocyte clearance compared to ASAQ in children with uncomplicated Plasmodium falciparum malaria. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04369-2.
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9
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Muema JM, Bargul JL, Obonyo MA, Njeru SN, Matoke-Muhia D, Mutunga JM. Contemporary exploitation of natural products for arthropod-borne pathogen transmission-blocking interventions. Parasit Vectors 2022; 15:298. [PMID: 36002857 PMCID: PMC9404607 DOI: 10.1186/s13071-022-05367-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 06/16/2022] [Indexed: 11/26/2022] Open
Abstract
An integrated approach to innovatively counter the transmission of various arthropod-borne diseases to humans would benefit from strategies that sustainably limit onward passage of infective life cycle stages of pathogens and parasites to the insect vectors and vice versa. Aiming to accelerate the impetus towards a disease-free world amid the challenges posed by climate change, discovery, mindful exploitation and integration of active natural products in design of pathogen transmission-blocking interventions is of high priority. Herein, we provide a review of natural compounds endowed with blockade potential against transmissible forms of human pathogens reported in the last 2 decades from 2000 to 2021. Finally, we propose various translational strategies that can exploit these pathogen transmission-blocking natural products into design of novel and sustainable disease control interventions. In summary, tapping these compounds will potentially aid in integrated combat mission to reduce disease transmission trends.
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Affiliation(s)
- Jackson M Muema
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology (JKUAT), P.O. Box 62000, Nairobi, 00200, Kenya.
| | - Joel L Bargul
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology (JKUAT), P.O. Box 62000, Nairobi, 00200, Kenya.,International Centre of Insect Physiology and Ecology (Icipe), P.O. Box 30772, Nairobi, 00100, Kenya
| | - Meshack A Obonyo
- Department of Biochemistry and Molecular Biology, Egerton University, P.O. Box 536, Egerton, 20115, Kenya
| | - Sospeter N Njeru
- Centre for Traditional Medicine and Drug Research (CTMDR), Kenya Medical Research Institute (KEMRI), P.O. Box 54840, Nairobi, 00200, Kenya
| | - Damaris Matoke-Muhia
- Centre for Biotechnology Research Development (CBRD), Kenya Medical Research Institute (KEMRI), P.O. Box 54840, Nairobi, 00200, Kenya
| | - James M Mutunga
- Department of Biological Sciences, Mount Kenya University (MKU), P.O. Box 54, Thika, 01000, Kenya.,School of Engineering Design, Technology and Professional Programs, Pennsylvania State University, University Park, PA, 16802, USA
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Mughal H, Bell EC, Mughal K, Derbyshire ER, Freundlich JS. Random Forest Model Predictions Afford Dual-Stage Antimalarial Agents. ACS Infect Dis 2022; 8:1553-1562. [PMID: 35894649 PMCID: PMC9987178 DOI: 10.1021/acsinfecdis.2c00189] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The need for novel antimalarials is apparent given the continuing disease burden worldwide, despite significant drug discovery advances from the bench to the bedside. In particular, small-molecule agents with potent efficacy against both the liver and blood stages of Plasmodium parasite infection are critical for clinical settings as they would simultaneously prevent and treat malaria with a reduced selection pressure for resistance. While experimental screens for such dual-stage inhibitors have been conducted, the time and cost of these efforts limit their scope. Here, we have focused on leveraging machine learning approaches to discover novel antimalarials with such properties. A random forest modeling approach was taken to predict small molecules with in vitro efficacy versus liver-stage Plasmodium berghei parasites and a lack of human liver cell cytotoxicity. Empirical validation of the model was achieved with the realization of hits with liver-stage efficacy after prospective scoring of a commercial diversity library and consideration of structural diversity. A subset of these hits also demonstrated promising blood-stage Plasmodium falciparum efficacy. These 18 validated dual-stage antimalarials represent novel starting points for drug discovery and mechanism of action studies with significant potential for seeding a new generation of therapies.
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Affiliation(s)
- Haseeb Mughal
- Department of Pharmacology, Physiology, and Neuroscience, Rutgers University – New Jersey Medical School, 185 South Orange Ave, Newark, NJ, 07103
| | - Elise C. Bell
- Department of Chemistry, Duke University, 124 Science Drive, Durham, NC 27708, USA
| | - Khadija Mughal
- Department of Pharmacology, Physiology, and Neuroscience, Rutgers University – New Jersey Medical School, 185 South Orange Ave, Newark, NJ, 07103
| | - Emily R. Derbyshire
- Department of Chemistry, Duke University, 124 Science Drive, Durham, NC 27708, USA
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, 213 Research Drive, Durham, NC 27710, USA
| | - Joel S. Freundlich
- Department of Pharmacology, Physiology, and Neuroscience, Rutgers University – New Jersey Medical School, 185 South Orange Ave, Newark, NJ, 07103
- Department of Medicine, Center for Emerging and Re-emerging Pathogens, Rutgers University – New Jersey Medical School, Newark, NJ, 07103
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Determinants of Patients’ Adherence to Malaria Treatment in the Democratic Republic of the Congo. Trop Med Infect Dis 2022; 7:tropicalmed7070138. [PMID: 35878149 PMCID: PMC9318296 DOI: 10.3390/tropicalmed7070138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 07/07/2022] [Accepted: 07/09/2022] [Indexed: 02/01/2023] Open
Abstract
(1) Background: Malaria heavily affects the Democratic Republic of the Congo (DRC) despite the use of effective drugs. Poor adherence to malaria treatment may contribute to this problem. (2) Methods: In one rural and one urban health area in each of the 11 former provinces of the DRC, all households with a case of malaria in the 15 days preceding the survey were selected and the patients or caregivers were interviewed. Adherence to malaria treatment was assessed by self-declaration about its completion. Logistic regression was used to assess predictors. (3) Results: 1732 households participated. Quinine was the most used drug; adherence to artesunate–amodiaquine was the lowest and the main reason for treatment discontinuation was adverse reactions. Predictors of adherence were residence in an urban area, university education, catholic religion, and adoption of recommended behaviour towards a malaria case. Adherence was significantly lower for responders who obtained information on antimalarials from Community Health Workers (CHW). (4) Conclusions: Usage of recommended drugs and adherence to malaria treatment need to be promoted, especially in rural areas, and CHW involvement needs to be improved. Awareness messages need to be made accessible and comprehensible to poorly educated populations and churches need to be involved.
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Reader J, van der Watt ME, Birkholtz LM. Streamlined and Robust Stage-Specific Profiling of Gametocytocidal Compounds Against Plasmodium falciparum. Front Cell Infect Microbiol 2022; 12:926460. [PMID: 35846744 PMCID: PMC9282888 DOI: 10.3389/fcimb.2022.926460] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 05/30/2022] [Indexed: 12/29/2022] Open
Abstract
Malaria elimination is dependent on the ability to target both the pathogenic and transmissible stages of the human malaria parasite, Plasmodium falciparum. These forms of the parasite are differentiated by unique developmental stages, each with their own biological mechanisms and processes. These individual stages therefore also respond differently to inhibitory compounds, and this complicates the discovery of multistage active antimalarial agents. The search for compounds with transmission-blocking activity has focused on screening for activity on mature gametocytes, with only limited descriptions available for the activity of such compounds on immature stage gametocytes. This therefore poses a gap in the profiling of antimalarial agents for pan-reactive, multistage activity to antimalarial leads. Here, we optimized an effective and robust strategy for the simple and cost-effective description of the stage-specific action of gametocytocidal antimalarial compounds.
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Affiliation(s)
- Janette Reader
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - Mariette E. van der Watt
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- Institute for Sustainable Malaria Control, School of Health Systems and Public Health, University of Pretoria, Pretoria, South Africa
| | - Lyn-Marié Birkholtz
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- *Correspondence: Lyn-Marié Birkholtz,
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Gametocyte-specific and all-blood-stage transmission-blocking chemotypes discovered from high throughput screening on Plasmodium falciparum gametocytes. Commun Biol 2022; 5:547. [PMID: 35668202 PMCID: PMC9170688 DOI: 10.1038/s42003-022-03510-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 05/19/2022] [Indexed: 11/25/2022] Open
Abstract
Blocking Plasmodium falciparum human-to-mosquito transmission is essential for malaria elimination, nonetheless drugs killing the pathogenic asexual stages are generally inactive on the parasite transmissible stages, the gametocytes. Due to technical and biological limitations in high throughput screening of non-proliferative stages, the search for gametocyte-killing molecules so far tested one tenth the number of compounds screened on asexual stages. Here we overcome these limitations and rapidly screened around 120,000 compounds, using not purified, bioluminescent mature gametocytes. Orthogonal gametocyte assays, selectivity assays on human cells and asexual parasites, followed by compound clustering, brought to the identification of 84 hits, half of which are gametocyte selective and half with comparable activity against sexual and asexual parasites. We validated seven chemotypes, three of which are, to the best of our knowledge, novel. These molecules are able to inhibit male gametocyte exflagellation and block parasite transmission through the Anopheles mosquito vector in a standard membrane feeding assay. This work shows that interrogating a wide and diverse chemical space, with a streamlined gametocyte HTS and hit validation funnel, holds promise for the identification of dual stage and gametocyte-selective compounds to be developed into new generation of transmission blocking drugs for malaria elimination. High-throughput screening of 120,000 compounds followed by counter-screening and validation assays reveals candidate antimalarial drugs that kill Plasmodium falciparum sexual and asexual blood stages blocking parasite transmission through mosquito.
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Consalvi S, Tammaro C, Appetecchia F, Biava M, Poce G. Malaria transmission blocking compounds: a patent review. Expert Opin Ther Pat 2022; 32:649-666. [PMID: 35240899 DOI: 10.1080/13543776.2022.2049239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
INTRODUCTION Despite substantial progress in the field, malaria remains a global health issue and currently available control strategies are not sufficient to achieve eradication. Agents able to prevent transmission are likely to have a strong impact on malaria control and have been prioritized as a primary objective to reduce the number of secondary infections. Therefore, there is an increased interest in finding novel drugs targeting sexual stages of Plasmodium and innovative methods to target malaria transmission from host to vector, and vice versa. AREAS COVERED This review covers innovative transmission-blocking inventions patented between 2015 and October 2021. The focus is on chemical interventions which could be used as "chemical vaccines" to prevent transmission (small molecules, carbohydrates, and polypeptides). EXPERT OPINION Even though the development of novel strategies to block transmission still requires fundamental additional research and a deeper understanding of parasite sexual stages biology, the research in this field has significantly accelerated. Among innovative inventions patented over the last six years, the surface-delivery of antimalarial drugs to kill transmission-stages parasites in mosquitoes holds the highest promise for success in malaria control strategies, opening completely new scenarios in malaria transmission-blocking drug discovery.
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Affiliation(s)
- Sara Consalvi
- Department of Chemistry and Technologies of Drug, Sapienza University of Rome, piazzale A. Moro 5, 00185 Rome, Italy
| | - Chiara Tammaro
- Department of Chemistry and Technologies of Drug, Sapienza University of Rome, piazzale A. Moro 5, 00185 Rome, Italy
| | - Federico Appetecchia
- Department of Chemistry and Technologies of Drug, Sapienza University of Rome, piazzale A. Moro 5, 00185 Rome, Italy
| | - Mariangela Biava
- Department of Chemistry and Technologies of Drug, Sapienza University of Rome, piazzale A. Moro 5, 00185 Rome, Italy
| | - Giovanna Poce
- Department of Chemistry and Technologies of Drug, Sapienza University of Rome, piazzale A. Moro 5, 00185 Rome, Italy
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Warrier DU, Dhanabalan AK, Krishnasamy G, Kolge H, Ghormade V, Gupta CR, Ambre PK, Shinde UA. Novel derivatives of arabinogalactan, pullulan & lactobionic acid for targeting asialoglycoprotein receptor: Biomolecular interaction, synthesis & evaluation. Int J Biol Macromol 2022; 207:683-699. [PMID: 35248606 DOI: 10.1016/j.ijbiomac.2022.02.176] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Revised: 02/19/2022] [Accepted: 02/27/2022] [Indexed: 11/19/2022]
Abstract
Targeted-drug administration to liver reduces side effects by minimising drug distribution to non-target organs and increases therapeutic efficacy by boosting drug concentration in target cells. In this study, arabinogalactan-(AG), pullulan-(PL) and lactobionic acid-(LA) were selected as natural ligands to target asialoglycoprotein receptor-(ASGPR-1) present on hepatocytes. In silico docking studies were performed and binding affinities of novel ligands viz. palmitoylated AG-(PAG), lauroylated AG-(LAG), palmitoylated PL-(PPL), lauroylated PL-(LPL) and lactobionic acid-adipic acid dihydrazide conjugate-(LAD) were compared with AG, PL and LA. These novel ligands were successfully synthesized and characterized. The ligands were incorporated into drug loaded nanostructured lipid carriers-(NLCs) for surface functionalization. HepG2 cellular internalization of hepatocyte-targeted NLCs was studied using fluorescence microscopy and LAD-decorated-drug loaded NLCs giving maximum cellular uptake were studied using confocal microscopy. Toxicity potential of LAD-decorated NLCs was assessed in vivo. Molecular docking results suggested that among the ligands, order of binding affinity was found to be LAD>PAG > PPL > LPL > LAG. Acute toxicity studies revealed hemocompatibility and absence of organ toxicity for ligand LAD. Additionally, the results establish proof-of-concept of enhanced targeting efficacy of novel ASGPR targeting ligands. These ligands can be used for surface modification of nanocarriers for future targeted delivery in treating various liver disorders.
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Affiliation(s)
- Deepa U Warrier
- Bombay College of Pharmacy, Kalina, Santacruz, Mumbai 400098, Maharashtra, India
| | - Anantha K Dhanabalan
- Centre of Advance study in Crystallography and Biophysics, University of Madras, Guindy campus, Chennai 600025, India
| | - Gunasekaran Krishnasamy
- Centre of Advance study in Crystallography and Biophysics, University of Madras, Guindy campus, Chennai 600025, India
| | - Henry Kolge
- Nanobioscience Group, Agharkar Research Institute, Pune 411004, India
| | - Vandana Ghormade
- Nanobioscience Group, Agharkar Research Institute, Pune 411004, India
| | - Chandan R Gupta
- Bombay College of Pharmacy, Kalina, Santacruz, Mumbai 400098, Maharashtra, India
| | - Premlata K Ambre
- Bombay College of Pharmacy, Kalina, Santacruz, Mumbai 400098, Maharashtra, India
| | - Ujwala A Shinde
- Bombay College of Pharmacy, Kalina, Santacruz, Mumbai 400098, Maharashtra, India.
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Birkholtz LM, Alano P, Leroy D. Transmission-blocking drugs for malaria elimination. Trends Parasitol 2022; 38:390-403. [DOI: 10.1016/j.pt.2022.01.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 01/19/2022] [Accepted: 01/24/2022] [Indexed: 12/24/2022]
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Dabira ED, Hachizovu S, Conteh B, Mendy A, Nyang H, Lawal B, Ndiath MO, Mulenga JM, Mwanza S, Borghini-Fuhrer I, Arbe-Barnes S, Miller R, Shin J, Duparc S, D'Alessandro U, Manyando C, Achan J. Efficacy, Safety and Tolerability of Pyronaridine-artesunate in Asymptomatic Malaria-infected Individuals: a Randomized Controlled Trial. Clin Infect Dis 2022; 74:180-188. [PMID: 33983371 PMCID: PMC8800175 DOI: 10.1093/cid/ciab425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND Pyronaridine-artesunate (PA) is a registered artemisinin-based combination therapy, potentially useful for mass drug administration campaigns. However, further data are needed to evaluate its efficacy, safety and tolerability as full or incomplete treatment in asymptomatic Plasmodium falciparum-infected individuals. METHODS This phase II, multi-center, open label, randomized clinical trial was conducted in The Gambia and Zambia. Participants with microscopically confirmed asymptomatic P. falciparum infection were randomly assigned (1:1:1) to receive a 3-day, 2-day, or 1-day treatment regimen of PA (180:60 mg), dosed according to bodyweight. The primary efficacy outcome was polymerase chain reaction (PCR)-adjusted adequate parasitological response (APR) at day 28 in the per-protocol population. RESULTS A total of 303 participants were randomized. Day 28 PCR-adjusted APR was 100% for both the 3-day (98/98) and 2-day regimens (96/96), and 96.8% (89/94) for the 1-day regimen. Efficacy was maintained at 100% until day 63 for the 3-day and 2-day regimens but declined to 94.4% (84/89) with the 1-day regimen. Adverse event frequency was similar between the 3-day (51.5% [52/101]), 2-day (52.5% [52/99]), and 1-day (54.4% [56/103]) regimens; the majority of adverse events were of grade 1 or 2 severity (85% [136/160]). Asymptomatic, transient increases (>3 times the upper limit of normal) in alanine aminotransferase/aspartate aminotransferase were observed for 6/301 (2.0%) participants. CONCLUSIONS PA had high efficacy and good tolerability in asymptomatic P. falciparum-infected individuals, with similar efficacy for the full 3-day and incomplete 2-day regimens. Although good adherence to the 3-day regimen should be encouraged, these results support the further investigation of PA for mass drug administration campaigns. CLINICAL TRIALS REGISTRATION NCT03814616.
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Affiliation(s)
- Edgard D Dabira
- Disease Control and Elimination Theme, Medical Research Council Unit, The Gambia at London School of Hygiene & Tropical Medicine, Fajara, The Gambia
| | | | - Bakary Conteh
- Disease Control and Elimination Theme, Medical Research Council Unit, The Gambia at London School of Hygiene & Tropical Medicine, Fajara, The Gambia
| | - Alieu Mendy
- Disease Control and Elimination Theme, Medical Research Council Unit, The Gambia at London School of Hygiene & Tropical Medicine, Fajara, The Gambia
| | - Haddy Nyang
- Disease Control and Elimination Theme, Medical Research Council Unit, The Gambia at London School of Hygiene & Tropical Medicine, Fajara, The Gambia
| | - Bolarinde Lawal
- Disease Control and Elimination Theme, Medical Research Council Unit, The Gambia at London School of Hygiene & Tropical Medicine, Fajara, The Gambia
| | - Mamadou Ousmane Ndiath
- Disease Control and Elimination Theme, Medical Research Council Unit, The Gambia at London School of Hygiene & Tropical Medicine, Fajara, The Gambia
| | | | | | | | | | | | | | - Stephan Duparc
- Medicines for Malaria Venture (MMV), Geneva, Switzerland
| | - Umberto D'Alessandro
- Disease Control and Elimination Theme, Medical Research Council Unit, The Gambia at London School of Hygiene & Tropical Medicine, Fajara, The Gambia
| | | | - Jane Achan
- Disease Control and Elimination Theme, Medical Research Council Unit, The Gambia at London School of Hygiene & Tropical Medicine, Fajara, The Gambia
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de Carvalho LP, Groeger-Otero S, Kreidenweiss A, Kremsner PG, Mordmüller B, Held J. Boromycin has Rapid-Onset Antibiotic Activity Against Asexual and Sexual Blood Stages of Plasmodium falciparum. Front Cell Infect Microbiol 2022; 11:802294. [PMID: 35096650 PMCID: PMC8795978 DOI: 10.3389/fcimb.2021.802294] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 12/27/2021] [Indexed: 11/25/2022] Open
Abstract
Boromycin is a boron-containing macrolide antibiotic produced by Streptomyces antibioticus with potent activity against certain viruses, Gram-positive bacteria and protozoan parasites. Most antimalarial antibiotics affect plasmodial organelles of prokaryotic origin and have a relatively slow onset of action. They are used for malaria prophylaxis and for the treatment of malaria when combined to a fast-acting drug. Despite the success of artemisinin combination therapies, the current gold standard treatment, new alternatives are constantly needed due to the ability of malaria parasites to become resistant to almost all drugs that are in heavy clinical use. In vitro antiplasmodial activity screens of tetracyclines (omadacycline, sarecycline, methacycline, demeclocycline, lymecycline, meclocycline), macrolides (oleandomycin, boromycin, josamycin, troleandomycin), and control drugs (chloroquine, clindamycin, doxycycline, minocycline, eravacycline) revealed boromycin as highly potent against Plasmodium falciparum and the zoonotic Plasmodium knowlesi. In contrast to tetracyclines, boromycin rapidly killed asexual stages of both Plasmodium species already at low concentrations (~ 1 nM) including multidrug resistant P. falciparum strains (Dd2, K1, 7G8). In addition, boromycin was active against P. falciparum stage V gametocytes at a low nanomolar range (IC50: 8.5 ± 3.6 nM). Assessment of the mode of action excluded the apicoplast as the main target. Although there was an ionophoric activity on potassium channels, the effect was too low to explain the drug´s antiplasmodial activity. Boromycin is a promising antimalarial candidate with activity against multiple life cycle stages of the parasite.
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Affiliation(s)
| | - Sara Groeger-Otero
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
| | - Andrea Kreidenweiss
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
- German Center for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
| | - Peter G. Kremsner
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
- German Center for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
| | - Benjamin Mordmüller
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
- German Center for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Jana Held
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
- German Center for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
- *Correspondence: Jana Held, ;
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The Artemiside-Artemisox-Artemisone-M1 Tetrad: Efficacies against Blood Stage P. falciparum Parasites, DMPK Properties, and the Case for Artemiside. Pharmaceutics 2021; 13:pharmaceutics13122066. [PMID: 34959347 PMCID: PMC8704606 DOI: 10.3390/pharmaceutics13122066] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 11/23/2021] [Accepted: 11/24/2021] [Indexed: 01/15/2023] Open
Abstract
Because of the need to replace the current clinical artemisinins in artemisinin combination therapies, we are evaluating fitness of amino-artemisinins for this purpose. These include the thiomorpholine derivative artemiside obtained in one scalable synthetic step from dihydroartemisinin (DHA) and the derived sulfone artemisone. We have recently shown that artemiside undergoes facile metabolism via the sulfoxide artemisox into artemisone and thence into the unsaturated metabolite M1; DHA is not a metabolite. Artemisox and M1 are now found to be approximately equipotent with artemiside and artemisone in vitro against asexual P. falciparum (Pf) blood stage parasites (IC50 1.5–2.6 nM). Against Pf NF54 blood stage gametocytes, artemisox is potently active (IC50 18.9 nM early-stage, 2.7 nM late-stage), although against the late-stage gametocytes, activity is expressed, like other amino-artemisinins, at a prolonged incubation time of 72 h. Comparative drug metabolism and pharmacokinetic (DMPK) properties were assessed via po and iv administration of artemiside, artemisox, and artemisone in a murine model. Following oral administration, the composite Cmax value of artemiside plus its metabolites artemisox and artemisone formed in vivo is some 2.6-fold higher than that attained following administration of artemisone alone. Given that efficacy of short half-life rapidly-acting antimalarial drugs such as the artemisinins is associated with Cmax, it is apparent that artemiside will be more active than artemisone in vivo, due to additive effects of the metabolites. As is evident from earlier data, artemiside indeed possesses appreciably greater efficacy in vivo against murine malaria. Overall, the higher exposure levels of active drug following administration of artemiside coupled with its synthetic accessibility indicate it is much the preferred drug for incorporation into rational new artemisinin combination therapies.
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Chia W, Gomez-Lorenzo MG, Castellote I, Tong JX, Chandramohanadas R, Thu Chu TT, Shen W, Go ML, de Cozar C, Crespo B, Almela MJ, Neria-Serrano F, Franco V, Gamo FJ, Tan KSW. High-Content Phenotypic Screen of a Focused TCAMS Drug Library Identifies Novel Disruptors of the Malaria Parasite Calcium Dynamics. ACS Chem Biol 2021; 16:2348-2372. [PMID: 34609851 DOI: 10.1021/acschembio.1c00512] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The search for new antimalarial drugs with unexplored mechanisms of action is currently one of the main objectives to combat the resistance already in the clinic. New drugs should target specific mechanisms that once initiated lead inevitably to the parasite's death and clearance and cause minimal toxicity to the host. One such new mode of action recently characterized is to target the parasite's calcium dynamics. Disruption of the calcium homeostasis is associated with compromised digestive vacuole membrane integrity and release of its contents, leading to programmed cell death-like features characterized by loss of mitochondrial membrane potential and DNA degradation. Intriguingly, chloroquine (CQ)-treated parasites were previously reported to exhibit such cellular features. Using a high-throughput phenotypic screen, we identified 158 physiological disruptors (hits) of parasite calcium distribution from a small subset of approximately 3000 compounds selected from the GSK TCAMS (Tres Cantos Anti-Malarial Set) compound library. These compounds were then extensively profiled for biological activity against various CQ- and artemisinin-resistant Plasmodium falciparum strains and stages. The hits were also examined for cytotoxicity, speed of antimalarial activity, and their possible inhibitory effects on heme crystallization. Overall, we identified three compounds, TCMDC-136230, -125431, and -125457, which were potent in inducing calcium redistribution but minimally inhibited heme crystallization. Molecular superimposition of the molecules by computational methods identified a common pharmacophore, with the best fit assigned to TCMDC-125457. There were low cytotoxicity or CQ cross-resistance issues for these three compounds. IC50 values of these three compounds were in the low micromolar range. In addition, TCMDC-125457 demonstrated high efficacy when pulsed in a single-dose combination with artesunate against tightly synchronized artemisinin-resistant ring-stage parasites. These results should add new drug options to the current armament of antimalarial drugs as well as provide promising starting points for development of drugs with non-classical modes of action.
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Affiliation(s)
- Wanni Chia
- Laboratory of Molecular and Cellular Parasitology, Department of Microbiology and Immunology, and Healthy Longevity Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, S117545, Singapore
| | - Maria G. Gomez-Lorenzo
- Global Health Discovery Incubator Unit, Global Health R&D, GlaxoSmithKline, Severo Ochoa 2, Tres Cantos, Madrid 28760, Spain
| | - Isabel Castellote
- Global Health Discovery Incubator Unit, Global Health R&D, GlaxoSmithKline, Severo Ochoa 2, Tres Cantos, Madrid 28760, Spain
| | - Jie Xin Tong
- Laboratory of Molecular and Cellular Parasitology, Department of Microbiology and Immunology, and Healthy Longevity Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, S117545, Singapore
| | - Rajesh Chandramohanadas
- Laboratory of Molecular and Cellular Parasitology, Department of Microbiology and Immunology, and Healthy Longevity Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, S117545, Singapore
| | - Trang Thi Thu Chu
- Laboratory of Molecular and Cellular Parasitology, Department of Microbiology and Immunology, and Healthy Longevity Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, S117545, Singapore
| | - Wanxiang Shen
- Department of Pharmacy, National University of Singapore, 18 Science Drive 4, S117543, Singapore
| | - Mei Lin Go
- Department of Pharmacy, National University of Singapore, 18 Science Drive 4, S117543, Singapore
| | - Cristina de Cozar
- Global Health Discovery Incubator Unit, Global Health R&D, GlaxoSmithKline, Severo Ochoa 2, Tres Cantos, Madrid 28760, Spain
| | - Benigno Crespo
- Global Health Discovery Incubator Unit, Global Health R&D, GlaxoSmithKline, Severo Ochoa 2, Tres Cantos, Madrid 28760, Spain
| | - Maria J. Almela
- Global Health Discovery Incubator Unit, Global Health R&D, GlaxoSmithKline, Severo Ochoa 2, Tres Cantos, Madrid 28760, Spain
| | - Fernando Neria-Serrano
- Global Health Discovery Incubator Unit, Global Health R&D, GlaxoSmithKline, Severo Ochoa 2, Tres Cantos, Madrid 28760, Spain
| | - Virginia Franco
- Global Health Discovery Incubator Unit, Global Health R&D, GlaxoSmithKline, Severo Ochoa 2, Tres Cantos, Madrid 28760, Spain
| | - Francisco-Javier Gamo
- Global Health Discovery Incubator Unit, Global Health R&D, GlaxoSmithKline, Severo Ochoa 2, Tres Cantos, Madrid 28760, Spain
| | - Kevin S. W. Tan
- Laboratory of Molecular and Cellular Parasitology, Department of Microbiology and Immunology, and Healthy Longevity Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, S117545, Singapore
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Studies of Potency and Efficacy of an Optimized Artemisinin-Quinoline Hybrid against Multiple Stages of the Plasmodium Life Cycle. Pharmaceuticals (Basel) 2021; 14:ph14111129. [PMID: 34832911 PMCID: PMC8620906 DOI: 10.3390/ph14111129] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 11/02/2021] [Accepted: 11/03/2021] [Indexed: 11/23/2022] Open
Abstract
A recently developed artemisinin-quinoline hybrid, named 163A, has been shown to display potent activity against the asexual blood stage of Plasmodium, the malaria parasite. In this study, we determined its in vitro cytotoxicity to mammalian cells, its potency to suppress P. berghei hepatic infection and to decrease the viability of P. falciparum gametocytes, in addition to determining whether the drug exhibits efficacy of a P. berghei infection in mice. This hybrid compound has a low level of cytotoxicity to mammalian cells and, conversely, a high level of selectivity. It is potent in the prevention of hepatic stage development as well as in killing gametocytes, denoting a potential blockage of malaria transmission. The hybrid presents a potent inhibitory activity for beta-hematin crystal formation, in which subsequent assays revealed that its endoperoxide component undergoes bioactivation by reductive reaction with ferrous heme towards the formation of heme-drug adducts; in parallel, the 7-chloroquinoline component has binding affinity for ferric hemin. Both structural components of the hybrid co-operate to enhance the inhibition of beta-hematin, and this bitopic ligand property is essential for arresting the growth of asexual blood parasites. We demonstrated the in vivo efficacy of the hybrid as an erythrocytic schizonticide agent in comparison to a chloroquine/artemisinin combination therapy. Collectively, the findings suggest that the bitopic property of the hybrid is highly operative on heme detoxification suppression, and this provides compelling evidence for explaining the action of the hybrid on the asexual blood stage. For sporozoite and gametocyte stages, the hybrid conserves the potency typically observed for endoperoxide drugs, and this is possibly achieved due to the redox chemistry of endoperoxide components with ferrous heme.
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Erhunse N, Sahal D. Protecting future antimalarials from the trap of resistance: Lessons from artemisinin-based combination therapy (ACT) failures. J Pharm Anal 2021; 11:541-554. [PMID: 34765267 PMCID: PMC8572664 DOI: 10.1016/j.jpha.2020.07.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Revised: 07/19/2020] [Accepted: 07/19/2020] [Indexed: 11/01/2022] Open
Abstract
Having faced increased clinical treatment failures with dihydroartemisinin-piperaquine (DHA-PPQ), Cambodia swapped the first line artemisinin-based combination therapy (ACT) from DHA-PPQ to artesunate-mefloquine given that parasites resistant to piperaquine are susceptible to mefloquine. However, triple mutants have now emerged, suggesting that drug rotations may not be adequate to keep resistance at bay. There is, therefore, an urgent need for alternative treatment strategies to tackle resistance and prevent its spread. A proper understanding of all contributors to artemisinin resistance may help us identify novel strategies to keep artemisinins effective until new drugs become available for their replacement. This review highlights the role of the key players in artemisinin resistance, the current strategies to deal with it and suggests ways of protecting future antimalarial drugs from bowing to resistance as their predecessors did.
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Affiliation(s)
- Nekpen Erhunse
- Malaria Drug Discovery Research Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
- Department of Biochemistry, Faculty of Life Sciences, University of Benin, Benin City, Edo-State, Nigeria
| | - Dinkar Sahal
- Malaria Drug Discovery Research Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
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23
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Pereira LM, de Luca G, Abichabki NDLM, Brochi JCV, Baroni L, Abreu-Filho PG, Yatsuda AP. Atovaquone, chloroquine, primaquine, quinine and tetracycline: antiproliferative effects of relevant antimalarials on Neospora caninum. REVISTA BRASILEIRA DE PARASITOLOGIA VETERINARIA = BRAZILIAN JOURNAL OF VETERINARY PARASITOLOGY : ORGAO OFICIAL DO COLEGIO BRASILEIRO DE PARASITOLOGIA VETERINARIA 2021; 30:e022120. [PMID: 33787719 DOI: 10.1590/s1984-29612021006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 01/20/2021] [Indexed: 01/21/2023]
Abstract
Neospora caninum is an apicomplexan parasite that causes abortion in cattle, resulting in significant economic losses. There is no commercial treatment for neosporosis, and drug repositioning is a fast strategy to test possible candidates against N. caninum. In this article, we describe the effects of atovaquone, chloroquine, quinine, primaquine and tetracycline on N. caninum proliferation. The IC50 concentrations in N. caninum were compared to the current information based on previous studies for Plasmodium and Toxoplasma gondii, correlating to the described mechanisms of action of each tested drug. The inhibitory patterns indicate similarities and differences among N. caninum, Plasmodium and T. gondii. For example, atovaquone demonstrates high antiparasitic activity in all the analyzed models, while chloroquine does not inhibit N. caninum. On the other hand, tetracycline is effective against Plasmodium and N. caninum, despite its low activity in T. gondii models. The repurposing of antimalarial drugs in N. caninum is a fast and inexpensive way to develop novel formulations using well-established compounds.
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Affiliation(s)
- Luiz Miguel Pereira
- Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo - USP, Ribeirão Preto, SP, Brasil
| | - Gabriela de Luca
- Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo - USP, Ribeirão Preto, SP, Brasil
| | - Nathália de Lima Martins Abichabki
- Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo - USP, Ribeirão Preto, SP, Brasil
| | - Jade Cabestre Venancio Brochi
- Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo - USP, Ribeirão Preto, SP, Brasil
| | - Luciana Baroni
- Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo - USP, Ribeirão Preto, SP, Brasil
| | - Péricles Gama Abreu-Filho
- Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo - USP, Ribeirão Preto, SP, Brasil
| | - Ana Patrícia Yatsuda
- Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo - USP, Ribeirão Preto, SP, Brasil
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24
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Rocamora F, Gupta P, Istvan ES, Luth MR, Carpenter EF, Kümpornsin K, Sasaki E, Calla J, Mittal N, Carolino K, Owen E, Llinás M, Ottilie S, Goldberg DE, Lee MCS, Winzeler EA. PfMFR3: A Multidrug-Resistant Modulator in Plasmodium falciparum. ACS Infect Dis 2021; 7:811-825. [PMID: 33715347 PMCID: PMC8042660 DOI: 10.1021/acsinfecdis.0c00676] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
![]()
In
malaria, chemical genetics is a powerful method for assigning
function to uncharacterized genes. MMV085203 and GNF-Pf-3600 are two
structurally related napthoquinone phenotypic screening hits that
kill both blood- and sexual-stage P. falciparum parasites in the low nanomolar to low micromolar range. In order
to understand their mechanism of action, parasites from two different
genetic backgrounds were exposed to sublethal concentrations of MMV085203
and GNF-Pf-3600 until resistance emerged. Whole genome sequencing
revealed all 17 resistant clones acquired nonsynonymous mutations
in the gene encoding the orphan apicomplexan transporter PF3D7_0312500
(pfmfr3) predicted to encode a member of the major
facilitator superfamily (MFS). Disruption of pfmfr3 and testing against a panel of antimalarial compounds showed decreased
sensitivity to MMV085203 and GNF-Pf-3600 as well as other compounds
that have a mitochondrial mechanism of action. In contrast, mutations
in pfmfr3 provided no protection against compounds
that act in the food vacuole or the cytosol. A dihydroorotate dehydrogenase
rescue assay using transgenic parasite lines, however, indicated a
different mechanism of action for both MMV085203 and GNF-Pf-3600 than
the direct inhibition of cytochrome bc1. Green fluorescent protein
(GFP) tagging of PfMFR3 revealed that it localizes to the parasite
mitochondrion. Our data are consistent with PfMFR3 playing roles in
mitochondrial transport as well as drug resistance for clinically
relevant antimalarials that target the mitochondria. Furthermore,
given that pfmfr3 is naturally polymorphic, naturally
occurring mutations may lead to differential sensitivity to clinically
relevant compounds such as atovaquone.
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Affiliation(s)
- Frances Rocamora
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | - Purva Gupta
- VA San Diego Healthcare System, Medical and Research Sections, La Jolla, California 92161, United States
- Department of Medicine, Division of Pulmonary and Critical Care, University of California, San Diego, La Jolla, California 92037, United States
| | - Eva S. Istvan
- Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63130, United States
| | - Madeline R. Luth
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | | | | | - Erika Sasaki
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | - Jaeson Calla
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | - Nimisha Mittal
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | - Krypton Carolino
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | - Edward Owen
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Huck Center for Malaria Research, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Manuel Llinás
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Huck Center for Malaria Research, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Sabine Ottilie
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | - Daniel E. Goldberg
- Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63130, United States
| | | | - Elizabeth A. Winzeler
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, California 92093, United States
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25
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Horatscheck A, Andrijevic A, Nchinda AT, Le Manach C, Paquet T, Khonde LP, Dam J, Pawar K, Taylor D, Lawrence N, Brunschwig C, Gibhard L, Njoroge M, Reader J, van der Watt M, Wicht K, de Sousa ACC, Okombo J, Maepa K, Egan TJ, Birkholtz LM, Basarab GS, Wittlin S, Fish PV, Street LJ, Duffy J, Chibale K. Identification of 2,4-Disubstituted Imidazopyridines as Hemozoin Formation Inhibitors with Fast-Killing Kinetics and In Vivo Efficacy in the Plasmodium falciparum NSG Mouse Model. J Med Chem 2020; 63:13013-13030. [PMID: 33103428 DOI: 10.1021/acs.jmedchem.0c01411] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
A series of 2,4-disubstituted imidazopyridines, originating from a SoftFocus Kinase library, was identified from a high throughput phenotypic screen against the human malaria parasite Plasmodium falciparum. Hit compounds showed moderate asexual blood stage activity. During lead optimization, several issues were flagged such as cross-resistance against the multidrug-resistant K1 strain, in vitro cytotoxicity, and cardiotoxicity and were addressed through structure-activity and structure-property relationship studies. Pharmacokinetic properties were assessed in mice for compounds showing desirable in vitro activity, a selectivity window over cytotoxicity, and microsomal metabolic stability. Frontrunner compound 37 showed good exposure in mice combined with good in vitro activity against the malaria parasite, which translated into in vivo efficacy in the P. falciparum NOD-scid IL-2Rγnull (NSG) mouse model. Preliminary mechanistic studies suggest inhibition of hemozoin formation as a contributing mode of action.
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Affiliation(s)
- André Horatscheck
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Ana Andrijevic
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Aloysius T Nchinda
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Claire Le Manach
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Tanya Paquet
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Lutete Peguy Khonde
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Jean Dam
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Kailash Pawar
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Dale Taylor
- Drug Discovery and Development Centre (H3D), Division of Clinical Pharmacology, University of Cape Town, Rondebosch 7701, South Africa
| | - Nina Lawrence
- Drug Discovery and Development Centre (H3D), Division of Clinical Pharmacology, University of Cape Town, Rondebosch 7701, South Africa
| | - Christel Brunschwig
- Drug Discovery and Development Centre (H3D), Division of Clinical Pharmacology, University of Cape Town, Rondebosch 7701, South Africa
| | - Liezl Gibhard
- Drug Discovery and Development Centre (H3D), Division of Clinical Pharmacology, University of Cape Town, Rondebosch 7701, South Africa
| | - Mathew Njoroge
- Drug Discovery and Development Centre (H3D), Division of Clinical Pharmacology, University of Cape Town, Rondebosch 7701, South Africa
| | - Janette Reader
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Hatfield, Pretoria 0028, South Africa
| | - Mariëtte van der Watt
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Hatfield, Pretoria 0028, South Africa
| | - Kathryn Wicht
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | | | - John Okombo
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Keletso Maepa
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Timothy J Egan
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa.,Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
| | - Lyn-Marie Birkholtz
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Hatfield, Pretoria 0028, South Africa
| | - Gregory S Basarab
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Sergio Wittlin
- Swiss Tropical and Public Health Institute ,Socinstrasse 57, 4002 Basel, Switzerland.,University of Basel, 4002 Basel, Switzerland
| | - Paul V Fish
- Alzheimer's Research UK, UCL Drug Discovery Institute, The Cruciform Building, University College London, Gower Street, London WC1E 6BT, U.K
| | - Leslie J Street
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - James Duffy
- Medicines for Malaria Venture, ICC, Route de Pré-Bois 20, P.O. Box 1826, 1215 Geneva, Switzerland
| | - Kelly Chibale
- South African Medical Research Council, Drug Discovery and Development Research Unit, Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa.,Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
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26
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Moyo P, Mugumbate G, Eloff JN, Louw AI, Maharaj VJ, Birkholtz LM. Natural Products: A Potential Source of Malaria Transmission Blocking Drugs? Pharmaceuticals (Basel) 2020; 13:E251. [PMID: 32957668 PMCID: PMC7558993 DOI: 10.3390/ph13090251] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 09/15/2020] [Accepted: 09/16/2020] [Indexed: 12/17/2022] Open
Abstract
The ability to block human-to-mosquito and mosquito-to-human transmission of Plasmodium parasites is fundamental to accomplish the ambitious goal of malaria elimination. The WHO currently recommends only primaquine as a transmission-blocking drug but its use is severely restricted by toxicity in some populations. New, safe and clinically effective transmission-blocking drugs therefore need to be discovered. While natural products have been extensively investigated for the development of chemotherapeutic antimalarial agents, their potential use as transmission-blocking drugs is comparatively poorly explored. Here, we provide a comprehensive summary of the activities of natural products (and their derivatives) of plant and microbial origins against sexual stages of Plasmodium parasites and the Anopheles mosquito vector. We identify the prevailing challenges and opportunities and suggest how these can be mitigated and/or exploited in an endeavor to expedite transmission-blocking drug discovery efforts from natural products.
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Affiliation(s)
- Phanankosi Moyo
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, Faculty of Natural and Agricultural Sciences, University of Pretoria, Private Bag x20, Hatfield, 0028 Pretoria, South Africa;
| | - Grace Mugumbate
- Department of Chemistry, School of Natural Sciences and Mathematics, Chinhoyi University of Technology, Private Bag, 7724 Chinhoyi, Zimbabwe;
| | - Jacobus N. Eloff
- Phytomedicine Programme, Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Private Bag x04, Onderstepoort 0110 Pretoria, South Africa;
| | - Abraham I. Louw
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, Faculty of Natural and Agricultural Sciences, University of Pretoria, Private Bag x20, Hatfield, 0028 Pretoria, South Africa;
| | - Vinesh J. Maharaj
- Department of Chemistry, Faculty of Natural and Agricultural Sciences, University of Pretoria, Private Bag x20, Hatfield, 0028 Pretoria, South Africa;
| | - Lyn-Marié Birkholtz
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, Faculty of Natural and Agricultural Sciences, University of Pretoria, Private Bag x20, Hatfield, 0028 Pretoria, South Africa;
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27
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Choi R, Michaels SA, Onu EC, Hulverson MA, Saha A, Coker ME, Weeks JC, Van Voorhis WC, Ojo KK. Taming the Boys for Global Good: Contraceptive Strategy to Stop Malaria Transmission. Molecules 2020; 25:molecules25122773. [PMID: 32560085 PMCID: PMC7356879 DOI: 10.3390/molecules25122773] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 06/10/2020] [Accepted: 06/14/2020] [Indexed: 12/21/2022] Open
Abstract
Transmission of human malaria parasites (Plasmodium spp.) by Anopheles mosquitoes is a continuous process that presents a formidable challenge for effective control of the disease. Infectious gametocytes continue to circulate in humans for up to four weeks after antimalarial drug treatment, permitting prolonged transmission to mosquitoes even after clinical cure. Almost all reported malaria cases are transmitted to humans by mosquitoes, and therefore decreasing the rate of Plasmodium transmission from humans to mosquitoes with novel transmission-blocking remedies would be an important complement to other interventions in reducing malaria incidence.
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Affiliation(s)
- Ryan Choi
- Center for Emerging and Re-Emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA 98109, USA; (R.C.); (S.A.M.); (M.A.H.); (A.S.); (W.C.V.V.)
| | - Samantha A. Michaels
- Center for Emerging and Re-Emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA 98109, USA; (R.C.); (S.A.M.); (M.A.H.); (A.S.); (W.C.V.V.)
| | - Emmanuel C. Onu
- Department of Pharmaceutical Microbiology, Faculty of Pharmacy, University of Ibadan, Ibadan, Nigeria; (E.C.O.); (M.E.C.)
| | - Matthew A. Hulverson
- Center for Emerging and Re-Emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA 98109, USA; (R.C.); (S.A.M.); (M.A.H.); (A.S.); (W.C.V.V.)
| | - Aparajita Saha
- Center for Emerging and Re-Emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA 98109, USA; (R.C.); (S.A.M.); (M.A.H.); (A.S.); (W.C.V.V.)
| | - Morenike E. Coker
- Department of Pharmaceutical Microbiology, Faculty of Pharmacy, University of Ibadan, Ibadan, Nigeria; (E.C.O.); (M.E.C.)
| | - Janis C. Weeks
- Department of Biology, University of Oregon, Eugene, OR 97403, USA;
| | - Wesley C. Van Voorhis
- Center for Emerging and Re-Emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA 98109, USA; (R.C.); (S.A.M.); (M.A.H.); (A.S.); (W.C.V.V.)
| | - Kayode K. Ojo
- Center for Emerging and Re-Emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA 98109, USA; (R.C.); (S.A.M.); (M.A.H.); (A.S.); (W.C.V.V.)
- Correspondence: ; Tel.: +1-206-543-0821
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28
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Abstract
As the world gets closer to eliminating malaria, the scientific community worldwide has begun to realize the importance of malaria transmission-blocking interventions. The onus of breaking the life cycle of the human malaria parasite Plasmodium falciparum predominantly rests upon transmission-blocking drugs because of emerging resistance to commonly used schizonticides and insecticides. This third part of our review series on malaria transmission-blocking entails transmission-blocking potential of preclinical transmission-blocking antimalarials and other non-malaria drugs/experimental compounds that are not in clinical or preclinical development for malaria but possess transmission-blocking potential. Collective analysis of the structure and the activity of these experimental compounds might pave the way toward generation of novel prototypes of next-generation transmission-blocking drugs.
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29
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Tibon NS, Ng CH, Cheong SL. Current progress in antimalarial pharmacotherapy and multi-target drug discovery. Eur J Med Chem 2019; 188:111983. [PMID: 31911292 DOI: 10.1016/j.ejmech.2019.111983] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 12/09/2019] [Accepted: 12/16/2019] [Indexed: 12/13/2022]
Abstract
Discovery and development of antimalarial drugs have long been dominated by single-target therapy. Continuous effort has been made to explore and identify different targets in malaria parasite crucial for the malaria treatment. The single-target drug therapy was initially successful, but it was later supplanted by combination therapy with multiple drugs to overcome drug resistance. Emergence of resistant strains even against the combination therapy has warranted a review of current antimalarial pharmacotherapy. This has led to the development of the new concept of covalent biotherapy, in which two or more pharmacophores are chemically bound to produce hybrid antimalarial drugs with multi-target functionalities. Herein, the review initially details the current pharmacotherapy for malaria as well as the conventional and novel targets of importance identified in the malaria parasite. Then, the rationale of multi-targeted therapy for malaria, approaches taken to develop the multi-target antimalarial hybrids, and the examples of hybrid molecules are comprehensively enumerated and discussed.
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Affiliation(s)
- Natasha Stella Tibon
- Department of Pharmaceutical Chemistry, School of Pharmacy, International Medical University, No. 126, Jalan Jalil Perkasa 19, Bukit Jalil, 57000, Kuala Lumpur, Malaysia
| | - Chew Hee Ng
- Department of Pharmaceutical Chemistry, School of Pharmacy, International Medical University, No. 126, Jalan Jalil Perkasa 19, Bukit Jalil, 57000, Kuala Lumpur, Malaysia.
| | - Siew Lee Cheong
- Department of Pharmaceutical Chemistry, School of Pharmacy, International Medical University, No. 126, Jalan Jalil Perkasa 19, Bukit Jalil, 57000, Kuala Lumpur, Malaysia.
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30
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Abstract
The scientific community worldwide has realized that malaria elimination will not be possible without development of safe and effective transmission-blocking interventions. Primaquine, the only WHO recommended transmission-blocking drug, is not extensively utilized because of the toxicity issues in G6PD deficient individuals. Therefore, there is an urgent need to develop novel therapeutic interventions that can target malaria parasites and effectively block transmission. But at first, it is imperative to unravel the existing portfolio of transmission-blocking drugs. This review highlights transmission-blocking potential of current antimalarial drugs and drugs that are in various stages of clinical development. The collective analysis of the relationships between the structure and the activity of transmission-blocking drugs is expected to help in the design of new transmission-blocking antimalarials.
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31
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Ivermectin Impairs the Development of Sexual and Asexual Stages of Plasmodium falciparum In Vitro. Antimicrob Agents Chemother 2019; 63:AAC.00085-19. [PMID: 31109978 DOI: 10.1128/aac.00085-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 05/09/2019] [Indexed: 12/11/2022] Open
Abstract
Ivermectin is the drug of choice for many parasitic infections, with more than one billion doses being distributed in onchocerciasis programs. The drug has been put into focus recently by the malaria community because of its potential to kill blood-sucking mosquitoes, thereby reducing malaria transmission. However, the activity of ivermectin against the malaria parasite itself has been only partly investigated. This study aimed to investigate the in vitro activity of ivermectin against asexual and sexual stages of Plasmodium falciparum Both asexual and late-stage gametocytes were incubated with ivermectin and control drugs in vitro The growth-inhibiting effects were assessed for asexual stages of different Plasmodium falciparum laboratory strains and culture-adapted clinical isolates using the histidine-rich protein 2 enzyme-linked immunosorbent assay technique. The effect against stage IV/V gametocytes was evaluated based on ATP quantification. Ivermectin showed activities at nanomolar concentrations against asexual stages (50% inhibitory concentration of ∼100 nM) and stage IV/V gametocytes (500 nM) of P. falciparum Stage-specific assays suggested that ivermectin arrests the parasite cycle at the trophozoite stage. Ivermectin might add a feature to its "wonder drug" properties with activity against asexual stages of the malaria parasite Plasmodium falciparum The observed activities might be difficult to reach with current regimens but will be more relevant with future high-dose regimens under investigation. Further studies should be performed to confirm these results in vitro and in vivo.
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Mackwitz MKW, Hesping E, Antonova-Koch Y, Diedrich D, Woldearegai TG, Skinner-Adams T, Clarke M, Schöler A, Limbach L, Kurz T, Winzeler EA, Held J, Andrews KT, Hansen FK. Structure-Activity and Structure-Toxicity Relationships of Peptoid-Based Histone Deacetylase Inhibitors with Dual-Stage Antiplasmodial Activity. ChemMedChem 2019; 14:912-926. [PMID: 30664827 PMCID: PMC6502651 DOI: 10.1002/cmdc.201800808] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Indexed: 12/17/2022]
Abstract
Novel malaria intervention strategies are of great importance, given the development of drug resistance in malaria-endemic countries. In this regard, histone deacetylases (HDACs) have emerged as new and promising malaria drug targets. In this work, we present the design, synthesis, and biological evaluation of 20 novel HDAC inhibitors with antiplasmodial activity. Based on a previously discovered peptoid-based hit compound, we modified all regions of the peptoid scaffold by using a one-pot multicomponent pathway and submonomer routes to gain a deeper understanding of the structure-activity and structure-toxicity relationships. Most compounds displayed potent activity against asexual blood-stage P. falciparum parasites, with IC50 values in the range of 0.0052-0.25 μm and promising selectivity over mammalian cells (SIPf3D7/HepG2 : 170-1483). In addition, several compounds showed encouraging sub-micromolar activity against P. berghei exo-erythrocytic forms (PbEEF). Our study led to the discovery of the hit compound N-(2-(benzylamino)-2-oxoethyl)-N-(4-(hydroxycarbamoyl)benzyl)-4-isopropylbenzamide (2 h) as a potent and parasite-specific dual-stage antiplasmodial HDAC inhibitor (IC50 Pf3D7=0.0052 μm, IC50 PbEEF=0.016 μm).
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Affiliation(s)
- Marcel K W Mackwitz
- Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, Medical Faculty, Leipzig University, Brüderstraße 34, 04103, Leipzig, Germany
| | - Eva Hesping
- Griffith Institute for Drug Discovery, Griffith University, Don Young Road, Nathan, QLD, 4111, Australia
| | - Yevgeniya Antonova-Koch
- Department of Pediatrics, School of Medicine, University of California, San Diego, 9500 Gilman Drive 0741, La Jolla, CA, 92093, USA
| | - Daniela Diedrich
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany
| | - Tamirat Gebru Woldearegai
- Institut für Tropenmedizin, Eberhard Karls Universität Tübingen, Wilhelmstraße 27, 72074, Tübingen, Germany
| | - Tina Skinner-Adams
- Griffith Institute for Drug Discovery, Griffith University, Don Young Road, Nathan, QLD, 4111, Australia
| | - Mary Clarke
- Griffith Institute for Drug Discovery, Griffith University, Don Young Road, Nathan, QLD, 4111, Australia
| | - Andrea Schöler
- Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, Medical Faculty, Leipzig University, Brüderstraße 34, 04103, Leipzig, Germany
| | - Laura Limbach
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany
| | - Thomas Kurz
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany
| | - Elizabeth A Winzeler
- Department of Pediatrics, School of Medicine, University of California, San Diego, 9500 Gilman Drive 0741, La Jolla, CA, 92093, USA
| | - Jana Held
- Institut für Tropenmedizin, Eberhard Karls Universität Tübingen, Wilhelmstraße 27, 72074, Tübingen, Germany
| | - Katherine T Andrews
- Griffith Institute for Drug Discovery, Griffith University, Don Young Road, Nathan, QLD, 4111, Australia
| | - Finn K Hansen
- Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, Medical Faculty, Leipzig University, Brüderstraße 34, 04103, Leipzig, Germany
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Yahiya S, Rueda-Zubiaurre A, Delves MJ, Fuchter MJ, Baum J. The antimalarial screening landscape-looking beyond the asexual blood stage. Curr Opin Chem Biol 2019; 50:1-9. [PMID: 30875617 PMCID: PMC6591700 DOI: 10.1016/j.cbpa.2019.01.029] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 01/28/2019] [Accepted: 01/30/2019] [Indexed: 12/20/2022]
Abstract
In recent years, the research agenda to tackle global morbidity and mortality from malaria disease has shifted towards innovation, in the hope that efforts at the frontiers of scientific research may re-invigorate gains made towards eradication. Discovery of new antimalarial drugs with novel chemotypes or modes of action lie at the heart of these efforts. There is a particular interest in drug candidates that target stages of the malaria parasite lifecycle beyond the symptomatic asexual blood stages. This is especially important given the spectre of emerging drug resistance to all current frontline antimalarials. One approach gaining increased interest is the potential of designing novel drugs that target parasite passage from infected individual to feeding mosquito and back again. Action of such therapeutics is geared much more at the population level rather than just concerned with the infected individual. The search for novel drugs active against these stages has been helped by improvements to in vitro culture of transmission and pre-erythrocytic parasite lifecycle stages, robotic automation and high content imaging, methodologies that permit the high-throughput screening (HTS) of compound libraries for drug discovery. Here, we review recent advances in the antimalarial screening landscape, focussed on transmission blocking as a key aim for drug-treatment campaigns of the future.
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Affiliation(s)
- Sabrina Yahiya
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London SW7 2AZ, UK
| | - Ainoa Rueda-Zubiaurre
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 OBZ, UK
| | - Michael J Delves
- London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Matthew J Fuchter
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 OBZ, UK
| | - Jake Baum
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London SW7 2AZ, UK.
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Moyo P, Kunyane P, Selepe MA, Eloff JN, Niemand J, Louw AI, Maharaj VJ, Birkholtz LM. Bioassay-guided isolation and identification of gametocytocidal compounds from Artemisia afra (Asteraceae). Malar J 2019; 18:65. [PMID: 30849984 PMCID: PMC6408838 DOI: 10.1186/s12936-019-2694-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 03/01/2019] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Optimal adoption of the malaria transmission-blocking strategy is currently limited by lack of safe and efficacious drugs. This has sparked the exploration of different sources of drugs in search of transmission-blocking agents. While plant species have been extensively investigated in search of malaria chemotherapeutic agents, comparatively less effort has been channelled towards exploring them in search of transmission-blocking drugs. Artemisia afra (Asteraceae), a prominent feature of South African folk medicine, is used for the treatment of a number of diseases, including malaria. In search of transmission-blocking compounds aimed against Plasmodium parasites, the current study endeavoured to isolate and identify gametocytocidal compounds from A. afra. METHODS A bioassay-guided isolation approach was adopted wherein a combination of solvent-solvent partitioning and gravity column chromatography was used. Collected fractions were continuously screened in vitro for their ability to inhibit the viability of primarily late-stage gametocytes of Plasmodium falciparum (NF54 strain), using a parasite lactate dehydrogenase assay. Chemical structures of isolated compounds were elucidated using UPLC-MS/MS and NMR data analysis. RESULTS Two guaianolide sesquiterpene lactones, 1α,4α-dihydroxybishopsolicepolide and yomogiartemin, were isolated and shown to be active (IC50 < 10 μg/ml; ~ 10 μM) against both gametocytes and intra-erythrocytic asexual P. falciparum parasites. Interestingly, 1α,4α-dihydroxybishopsolicepolide was significantly more potent against late-stage gametocytes than to early-stage gametocytes and intra-erythrocytic asexual P. falciparum parasites. Additionally, both isolated compounds were not overly cytotoxic against HepG2 cells in vitro. CONCLUSION This study provides the first instance of isolated compounds from A. afra against P. falciparum gametocytes as a starting point for further investigations on more plant species in search of transmission-blocking compounds.
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Affiliation(s)
- Phanankosi Moyo
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Faculty of Natural and Agricultural Sciences, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag x20, Hatfield, 0028, South Africa
| | - Phaladi Kunyane
- Department of Chemistry, Faculty of Natural and Agricultural Sciences, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag x20, Hatfield, 0028, South Africa
| | - Mamoalosi A Selepe
- Department of Chemistry, Faculty of Natural and Agricultural Sciences, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag x20, Hatfield, 0028, South Africa
| | - Jacobus N Eloff
- Phytomedicine Programme, Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Private Bag x04, Onderstepoort, Pretoria, 0110, South Africa
| | - Jandeli Niemand
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Faculty of Natural and Agricultural Sciences, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag x20, Hatfield, 0028, South Africa
| | - Abraham I Louw
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Faculty of Natural and Agricultural Sciences, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag x20, Hatfield, 0028, South Africa
| | - Vinesh J Maharaj
- Department of Chemistry, Faculty of Natural and Agricultural Sciences, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag x20, Hatfield, 0028, South Africa
| | - Lyn-Marie Birkholtz
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Faculty of Natural and Agricultural Sciences, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag x20, Hatfield, 0028, South Africa.
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Ouologuem DT, Kone CO, Fofana B, Sidibe B, Togo AH, Dembele D, Toure S, Koumare S, Toure O, Sagara I, Toure A, Dao A, Doumbo OK, Djimde AA. Differential infectivity of gametocytes after artemisinin-based combination therapy of uncomplicated falciparum malaria. Afr J Lab Med 2018; 7:784. [PMID: 30568901 PMCID: PMC6295776 DOI: 10.4102/ajlm.v7i2.784] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 09/30/2018] [Indexed: 11/01/2022] Open
Abstract
Background Most malaria-endemic countries use artemisinin-based combination therapy (ACT) as their first-line treatment. ACTs are known to be highly effective on asexual stages of the malaria parasite. Malaria transmission and the spread of resistant parasites depend on the infectivity of gametocytes. The effect of the current ACT regimens on gametocyte infectivity is unclear. Objectives This study aimed to determine the infectivity of gametocytes to Anopheles gambiae following ACT treatment in the field. Methods During a randomised controlled trial in Bougoula-Hameau, Mali, conducted from July 2005 to July 2007, volunteers with uncomplicated malaria were randomised to receive artemether-lumefantrine, artesunate-amodiaquine, or artesunate-sulfadoxine/pyrimethamine. Volunteers were followed for 28 days, and gametocyte carriage was assessed. Direct skin feeding assays were performed on gametocyte carriers before and after ACT administration. Results Following artemether-lumefantrine treatment, gametocyte carriage decreased steadily from Day 0 to Day 21 post-treatment initiation. In contrast, for the artesunate-amodiaquine and artesunate-sulfadoxine/pyrimethamine arms, gametocyte carriage increased on Day 3 and remained constant until Day 7 before decreasing afterward. Mosquito feeding assays showed that artemether-lumefantrine and artesunate-amodiaquine significantly increased gametocyte infectivity to Anopheles gambiae sensu lato (s.l.) (p < 10-4), whereas artesunate-sulfadoxine/pyrimethamine decreased gametocyte infectivity in this setting (p = 0.03). Conclusion Different ACT regimens could lead to gametocyte populations with different capacity to infect the Anopheles vector. Frequent assessment of the effect of antimalarials on gametocytogenesis and gametocyte infectivity may be required for the full assessment of treatment efficacy, the potential for spread of drug resistance and malaria transmission in the field.
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Affiliation(s)
- Dinkorma T Ouologuem
- Malaria Research and Training Center, Department of Epidemiology of Parasitic Diseases, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Cheick O Kone
- Malaria Research and Training Center, Department of Epidemiology of Parasitic Diseases, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Bakary Fofana
- Malaria Research and Training Center, Department of Epidemiology of Parasitic Diseases, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Bakary Sidibe
- Malaria Research and Training Center, Department of Epidemiology of Parasitic Diseases, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Amadou H Togo
- Malaria Research and Training Center, Department of Epidemiology of Parasitic Diseases, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Demba Dembele
- Malaria Research and Training Center, Department of Epidemiology of Parasitic Diseases, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Sekou Toure
- Malaria Research and Training Center, Department of Epidemiology of Parasitic Diseases, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Sekou Koumare
- Malaria Research and Training Center, Department of Epidemiology of Parasitic Diseases, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Ousmane Toure
- Malaria Research and Training Center, Department of Epidemiology of Parasitic Diseases, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Issaka Sagara
- Malaria Research and Training Center, Department of Epidemiology of Parasitic Diseases, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Abdoulaye Toure
- Malaria Research and Training Center, Department of Epidemiology of Parasitic Diseases, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Adama Dao
- Malaria Research and Training Center, Department of Epidemiology of Parasitic Diseases, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Ogobara K Doumbo
- Malaria Research and Training Center, Department of Epidemiology of Parasitic Diseases, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Abdoulaye A Djimde
- Malaria Research and Training Center, Department of Epidemiology of Parasitic Diseases, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
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Critical examination of approaches exploited to assess the effectiveness of transmission-blocking drugs for malaria. Future Med Chem 2018; 10:2619-2639. [PMID: 30499742 DOI: 10.4155/fmc-2018-0169] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
In the absence of clinically proven vaccines and emerging resistance to common antimalarials and insecticides, the onus of interrupting the life cycle of Plasmodium falciparum, is upon the transmission-blocking drugs. Current transmission-blocking drug primaquine finds its use restricted because of associated hemolytic toxicity issues in Glucose-6-Phosphate-Dehydrogenase deficient individuals. This article provides an extensive review of the assays used by the investigators to evaluate the transmission-blocking activity of drugs. Furthermore, limitations in existing transmission-blocking assessment approaches/studies are also covered in detail. This review is expected to help in the identification of lacunae in current understanding of transmission-blocking strategies, which are hindering our efforts to develop sustainable and effective transmission-blocking interventions.
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Screening the Pathogen Box for Molecules Active against Plasmodium Sexual Stages Using a New Nanoluciferase-Based Transgenic Line of P. berghei Identifies Transmission-Blocking Compounds. Antimicrob Agents Chemother 2018; 62:AAC.01053-18. [PMID: 30181368 DOI: 10.1128/aac.01053-18] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 08/28/2018] [Indexed: 12/12/2022] Open
Abstract
Malaria remains an important parasitic disease with a large morbidity and mortality burden. Plasmodium transmission-blocking (TB) compounds are essential for achieving malaria elimination efforts. Recent efforts to develop high-throughput screening (HTS) methods to identify compounds that inhibit or kill gametocytes, the Plasmodium sexual stage infectious to mosquitoes, have yielded insight into new TB compounds. However, the activities of these compounds against gametes, formed in the first minutes of mosquito infection, are typically not assessed, unless screened in a standard membrane feeding assay, a labor-intensive assay. We demonstrate here the generation of a Plasmodium model for drug screens against gametes and fertilization. The new P. berghei line, named Ookluc, was genetically and pharmacologically validated and scalable for HTS. Screening the Pathogen Box from the Medicines for Malaria Venture using the new model identified promising TB compounds. The use of Ookluc in different libraries of compounds may aid in the identification of transmission-blocking drugs not assessed in screens against asexual stages or gametocytes.
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Diedrich D, Stenzel K, Hesping E, Antonova-Koch Y, Gebru T, Duffy S, Fisher G, Schöler A, Meister S, Kurz T, Avery VM, Winzeler EA, Held J, Andrews KT, Hansen FK. One-pot, multi-component synthesis and structure-activity relationships of peptoid-based histone deacetylase (HDAC) inhibitors targeting malaria parasites. Eur J Med Chem 2018; 158:801-813. [PMID: 30245402 PMCID: PMC6195125 DOI: 10.1016/j.ejmech.2018.09.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 09/05/2018] [Accepted: 09/06/2018] [Indexed: 12/30/2022]
Abstract
Malaria drug discovery has shifted from a focus on targeting asexual blood stage parasites, to the development of drugs that can also target exo-erythrocytic forms and/or gametocytes in order to prevent malaria and/or parasite transmission. In this work, we aimed to develop parasite-selective histone deacetylase inhibitors (HDACi) with activity against the disease-causing asexual blood stages of Plasmodium malaria parasites as well as with causal prophylactic and/or transmission blocking properties. An optimized one-pot, multi-component protocol via a sequential Ugi four-component reaction and hydroxylaminolysis was used for the preparation of a panel of peptoid-based HDACi. Several compounds displayed potent activity against drug-sensitive and drug-resistant P. falciparum asexual blood stages, high parasite-selectivity and submicromolar activity against exo-erythrocytic forms of P. berghei. Our optimization study resulted in the discovery of the hit compound 1u which combines high activity against asexual blood stage parasites (Pf 3D7 IC50: 4 nM; Pf Dd2 IC50: 1 nM) and P. berghei exo-erythrocytic forms (Pb EEF IC50: 25 nM) with promising parasite-specific activity (SIPf3D7/HepG2: 2496, SIPfDd2/HepG2: 9990, and SIPbEEF/HepG2: 400).
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Affiliation(s)
- Daniela Diedrich
- Institut für Pharmazeutische und Medizinische Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225, Düsseldorf, Germany
| | - Katharina Stenzel
- Institut für Pharmazeutische und Medizinische Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225, Düsseldorf, Germany; Griffith Institute for Drug Discovery, Griffith University, Don Young Road, Nathan Campus, QLD, 4111, Australia
| | - Eva Hesping
- Griffith Institute for Drug Discovery, Griffith University, Don Young Road, Nathan Campus, QLD, 4111, Australia
| | - Yevgeniya Antonova-Koch
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA, 92093, United States
| | - Tamirat Gebru
- Institut für Tropenmedizin, Eberhard Karls Universität Tübingen, Wilhelmstraße 27, 72074, Tübingen, Germany
| | - Sandra Duffy
- Griffith Institute for Drug Discovery, Griffith University, Don Young Road, Nathan Campus, QLD, 4111, Australia
| | - Gillian Fisher
- Griffith Institute for Drug Discovery, Griffith University, Don Young Road, Nathan Campus, QLD, 4111, Australia
| | - Andrea Schöler
- Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, Medical Faculty, Leipzig University, Brüderstraße 34, 04103, Leipzig, Germany
| | - Stephan Meister
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA, 92093, United States
| | - Thomas Kurz
- Institut für Pharmazeutische und Medizinische Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225, Düsseldorf, Germany
| | - Vicky M Avery
- Griffith Institute for Drug Discovery, Griffith University, Don Young Road, Nathan Campus, QLD, 4111, Australia
| | - Elizabeth A Winzeler
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA, 92093, United States
| | - Jana Held
- Institut für Tropenmedizin, Eberhard Karls Universität Tübingen, Wilhelmstraße 27, 72074, Tübingen, Germany
| | - Katherine T Andrews
- Griffith Institute for Drug Discovery, Griffith University, Don Young Road, Nathan Campus, QLD, 4111, Australia.
| | - Finn K Hansen
- Institut für Pharmazeutische und Medizinische Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225, Düsseldorf, Germany; Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, Medical Faculty, Leipzig University, Brüderstraße 34, 04103, Leipzig, Germany.
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39
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Delves MJ, Miguel-Blanco C, Matthews H, Molina I, Ruecker A, Yahiya S, Straschil U, Abraham M, León ML, Fischer OJ, Rueda-Zubiaurre A, Brandt JR, Cortés Á, Barnard A, Fuchter MJ, Calderón F, Winzeler EA, Sinden RE, Herreros E, Gamo FJ, Baum J. A high throughput screen for next-generation leads targeting malaria parasite transmission. Nat Commun 2018; 9:3805. [PMID: 30228275 PMCID: PMC6143625 DOI: 10.1038/s41467-018-05777-2] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 07/26/2018] [Indexed: 01/22/2023] Open
Abstract
Spread of parasite resistance to artemisinin threatens current frontline antimalarial therapies, highlighting the need for new drugs with alternative modes of action. Since only 0.2–1% of asexual parasites differentiate into sexual, transmission-competent forms, targeting this natural bottleneck provides a tangible route to interrupt disease transmission and mitigate resistance selection. Here we present a high-throughput screen of gametogenesis against a ~70,000 compound diversity library, identifying seventeen drug-like molecules that target transmission. Hit molecules possess varied activity profiles including male-specific, dual acting male–female and dual-asexual-sexual, with one promising N-((4-hydroxychroman-4-yl)methyl)-sulphonamide scaffold found to have sub-micromolar activity in vitro and in vivo efficacy. Development of leads with modes of action focussed on the sexual stages of malaria parasite development provide a previously unexplored base from which future therapeutics can be developed, capable of preventing parasite transmission through the population. Sexual forms of malaria parasites are responsible for transmission to the mosquito. Anti-malarial drug resistance remains a serious problem and requires advent of new drug therapies. Here, the authors present a high-throughput screen of potential antimalarial compounds, identifying seventeen drug-like molecules specifically targeting transmission.
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Affiliation(s)
- Michael J Delves
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, SW7 2AZ, UK
| | - Celia Miguel-Blanco
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, SW7 2AZ, UK.,Diseases of the Developing World (DDW), GlaxoSmithKline, 28760, Tres Cantos, Madrid, Spain
| | - Holly Matthews
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, SW7 2AZ, UK
| | - Irene Molina
- Diseases of the Developing World (DDW), GlaxoSmithKline, 28760, Tres Cantos, Madrid, Spain
| | - Andrea Ruecker
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, SW7 2AZ, UK
| | - Sabrina Yahiya
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, SW7 2AZ, UK
| | - Ursula Straschil
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, SW7 2AZ, UK
| | - Matthew Abraham
- School of Medicine, University of California San Diego, 9500 Gilman Drive 0760, La Jolla, CA, 92093, USA
| | - María Luisa León
- Diseases of the Developing World (DDW), GlaxoSmithKline, 28760, Tres Cantos, Madrid, Spain
| | - Oliver J Fischer
- Department of Chemistry, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ, UK
| | - Ainoa Rueda-Zubiaurre
- Department of Chemistry, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ, UK
| | - Jochen R Brandt
- Department of Chemistry, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ, UK
| | - Álvaro Cortés
- Diseases of the Developing World (DDW), GlaxoSmithKline, 28760, Tres Cantos, Madrid, Spain
| | - Anna Barnard
- Department of Chemistry, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ, UK
| | - Matthew J Fuchter
- Department of Chemistry, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ, UK
| | - Félix Calderón
- Diseases of the Developing World (DDW), GlaxoSmithKline, 28760, Tres Cantos, Madrid, Spain
| | - Elizabeth A Winzeler
- School of Medicine, University of California San Diego, 9500 Gilman Drive 0760, La Jolla, CA, 92093, USA
| | - Robert E Sinden
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, SW7 2AZ, UK
| | - Esperanza Herreros
- Diseases of the Developing World (DDW), GlaxoSmithKline, 28760, Tres Cantos, Madrid, Spain
| | - Francisco J Gamo
- Diseases of the Developing World (DDW), GlaxoSmithKline, 28760, Tres Cantos, Madrid, Spain.
| | - Jake Baum
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, SW7 2AZ, UK.
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Functional Conservation of P48/45 Proteins in the Transmission Stages of Plasmodium vivax (Human Malaria Parasite) and P. berghei (Murine Malaria Parasite). mBio 2018; 9:mBio.01627-18. [PMID: 30181253 PMCID: PMC6123445 DOI: 10.1128/mbio.01627-18] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Sexual-stage proteins have a distinct function in the mosquito vector during transmission and also represent targets for the development of malaria transmission-blocking vaccine. P48/45, a leading vaccine candidate, is critical for male gamete fertility and shows >50% similarity across various species of Plasmodium We evaluated functional conservation of P48/45 in Plasmodium vivax and P. berghei with the motivation to establish transgenic P. berghei strains expressing P. vivax P48/45 (Pvs48/45) in an in vivo assay to evaluate the transmission-blocking activity of antibodies elicited by Pvs48/45. Homologous recombination was employed to target P. bergheis48/45 (pbs48/45) for knockout (KO) or for its replacement by two different forms of P. vivaxs48/45 (pvs48/45) (the full-length gene and a chimeric gene consisting of pbs48/45 5' signal and 3' anchor sequences flanking pvs48/45). Expression of Pvs48/45 in transgenic parasites and lack of expression of any P48/45 in KO parasites were confirmed by reverse transcription-PCR (RT-PCR) and Western blotting. Both transgenic and knockout parasites revealed asexual growth kinetics in mice comparable to that seen with wild-type parasites. When employed in mosquito infection experiments, both transgenic parasite strains remained transmission competent and developed into infectious sporozoites, whereas the knockout parasites were incapable of establishing mosquito-stage infection. These results indicate the functional conservation of P48/45 protein during transmission, and the transgenic parasites generated in this study represent a valuable tool to evaluate the protective efficacy of transmission-blocking antibodies elicited by Pvs48/45-based vaccines using an in vivo mouse animal assay instead of ex vivo membrane feeding assays (MFA) relying on access to P. vivax gametocytes from infected patients.IMPORTANCE Malaria transmission depends upon successful sexual differentiation and maturation of parasites in the vertebrate host and further development in the mosquito midgut. Stage-specific proteins in the sexual stages have been shown to play a critical role in development and successful transmission through the anopheline mosquito vector. Studies presented in the current manuscript evaluated functional conservation of one such protein, P48/45, in two diverse species (P. berghei and P. vivax). Replacement of endogenous pbs48/45 in P. berghei with pvs48/45 (P. vivax homologue) did not affect the viability of the parasites, and the transgenic parasites expressing Pvs48/45 remained transmission competent. These studies establish not only the functional conservation of P48/45 in P. berghei and P. vivax but also offer an opportunity to develop an in vivo test model for Pvs48/45-based P. vivax transmission-blocking vaccines, currently under development.
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Artemisone and Artemiside Are Potent Panreactive Antimalarial Agents That Also Synergize Redox Imbalance in Plasmodium falciparum Transmissible Gametocyte Stages. Antimicrob Agents Chemother 2018; 62:AAC.02214-17. [PMID: 29866868 DOI: 10.1128/aac.02214-17] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 05/18/2018] [Indexed: 11/20/2022] Open
Abstract
The emergence of resistance toward artemisinin combination therapies (ACTs) by the malaria parasite Plasmodium falciparum has the potential to severely compromise malaria control. Therefore, the development of new artemisinins in combination with new drugs that impart activities toward both intraerythrocytic proliferative asexual and transmissible gametocyte stages, in particular, those of resistant parasites, is urgently required. We define artemisinins as oxidant drugs through their ability to oxidize reduced flavin cofactors of flavin disulfide reductases critical for maintaining redox homeostasis in the malaria parasite. Here we compare the activities of 10-amino artemisinin derivatives toward the asexual and gametocyte stages of P. falciparum parasites. Of these, artemisone and artemiside inhibited asexual and gametocyte stages, particularly stage V gametocytes, in the low-nanomolar range. Further, treatment of both early and late gametocyte stages with artemisone or artemiside combined with the pro-oxidant redox partner methylene blue displayed notable synergism. These data suggest that modulation of redox homeostasis is likely an important druggable process, particularly in gametocytes, and this finding thereby enhances the prospect of using combinations of oxidant and redox drugs for malaria control.
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Roth JM, Sawa P, Omweri G, Osoti V, Makio N, Bradley J, Bousema T, Schallig HDFH, Mens PF. Plasmodium falciparum gametocyte dynamics after pyronaridine-artesunate or artemether-lumefantrine treatment. Malar J 2018; 17:223. [PMID: 29866116 PMCID: PMC5987563 DOI: 10.1186/s12936-018-2373-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 05/29/2018] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Artemisinin-based combinations differ in their impact on gametocyte prevalence and density. This study assessed female and male gametocyte dynamics after treating children with uncomplicated Plasmodium falciparum malaria with either pyronaridine-artesunate (PA) or artemether-lumefantrine (AL). METHODS Kenyan children with uncomplicated Plasmodium falciparum malaria were included and randomly assigned to PA or AL treatment. Filter paper blood samples were collected as a source of RNA for quantitative reverse-transcription PCR (qRT-PCR) and nucleic acid sequence based amplification (QT-NASBA) to detect female gametocytes (targeting Pfs25 mRNA). Male gametocytes were detected by qRT-PCR (targeting PfMGET mRNA). Duration of gametocyte carriage, the female and male gametocyte response and the agreement between qRT-PCR and QT-NASBA were determined. RESULTS The mean duration of female gametocyte carriage was significantly longer for PA (4.9 days) than for AL (3.8 days) as estimated by QT-NASBA (P = 0.036), but this difference was less clear when determined by Pfs25 qRT-PCR (4.5 days for PA and 3.7 for AL, P = 0.166). qRT-PCR based female gametocyte prevalence decreased from 100% (75/75) at baseline to 6.06% (4/66) at day 14 in the AL group and from 97.7% (83/85) to 13.9% (11/79) in the PA group. Male gametocyte prevalence decreased from 41.3% (31/75) at baseline to 19.7% (13/66) at day 14 in the AL group and from 35.3% (30/85) to 22.8% (18/79) in the PA group. There was good agreement between Pfs25 qRT-PCR and QT-NASBA female gametocyte prevalence (0.85, 95% CI 0.82-0.87). CONCLUSIONS This study indicates that female gametocyte clearance may be slightly faster after AL compared to PA. Male gametocytes showed similar post-treatment clearance between study arms. Future studies should further address potential differences between the post-treatment transmission potential after PA compared to AL. Trial registration This study is registered at clinicaltrials.gov under NCT02411994. Registration date: 8 April 2015. https://clinicaltrials.gov/ct2/show/NCT02411994?term=pyronaridine-artesunate&cond=Malaria&cntry=KE&rank=1.
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Affiliation(s)
- Johanna M Roth
- Department of Medical Microbiology, Laboratory for Clinical Parasitology, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
| | - Patrick Sawa
- Human Health Division, International Centre of Insect Physiology and Ecology, Mbita Point, Kenya
| | - George Omweri
- Human Health Division, International Centre of Insect Physiology and Ecology, Mbita Point, Kenya
| | - Victor Osoti
- Human Health Division, International Centre of Insect Physiology and Ecology, Mbita Point, Kenya
| | - Nicodemus Makio
- Human Health Division, International Centre of Insect Physiology and Ecology, Mbita Point, Kenya
| | - John Bradley
- Medical Research Council Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Teun Bousema
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Henk D F H Schallig
- Department of Medical Microbiology, Laboratory for Clinical Parasitology, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
| | - Pètra F Mens
- Department of Medical Microbiology, Laboratory for Clinical Parasitology, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
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Colmenarejo G, Lozano S, González-Cortés C, Calvo D, Sanchez-Garcia J, Matilla JLP, Leroy D, Rodrigues J. Predicting transmission blocking potential of anti-malarial compounds in the Mosquito Feeding Assay using Plasmodium falciparum Male Gamete Inhibition Assay. Sci Rep 2018; 8:7764. [PMID: 29773818 PMCID: PMC5958111 DOI: 10.1038/s41598-018-26125-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 05/04/2018] [Indexed: 02/01/2023] Open
Abstract
Plasmodium falciparum Standard Membrane Feeding Assay (PfSMFA) is the current gold standard mosquito based confirmatory transmission blocking (TrB) assay for human malaria. However, owing to its complexity only selected gametocytocidal molecules are progressed into SMFA. Predictive tools for evaluation of TrB behavior of compounds in SMFA would be extremely beneficial, but lack of substantially large data sets from many mosquito feeds preempts the ability to perform correlations between outcomes from in vitro assays and SMFA. Here, a total of 44 different anti-malarial compounds were screened for inhibitory effect on male gamete formation in exflagellation inhibition assay (EIA) and the same drug-treated parasites were fed to mosquitoes in SMFA. Regression analysis was performed between outcomes of the two assays and regression models were applied to a randomly selected validation set of four compounds indicating no overfitting and good predictive power. In addition, the pIC50 for 11 different compounds obtained in the EIA was also correlated with pIC50’s in SMFA. Resulting regression models provided pIC50 predictions in SMFA with reasonably good accuracy thereby demonstrating the use of a simple in vitro assay to predict TrB of molecules in a complex mosquito based assay.
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Affiliation(s)
- Gonzalo Colmenarejo
- Diseases of the Developing World (DDW), GlaxoSmithKline, Severo Ochoa 2, Tres Cantos, 28760, Madrid, Spain.,Biostatistics and Bioinformatics Unit, IMDEA Food Institute, CEI UAM+CSIC, Ctra Cantoblanco 8, 28049, Madrid, Spain
| | - Sonia Lozano
- Diseases of the Developing World (DDW), GlaxoSmithKline, Severo Ochoa 2, Tres Cantos, 28760, Madrid, Spain
| | - Carolina González-Cortés
- Diseases of the Developing World (DDW), GlaxoSmithKline, Severo Ochoa 2, Tres Cantos, 28760, Madrid, Spain.,Complejo Asistencial Universitario de León. Altos de Nava s/n, 24071, León, Spain
| | - David Calvo
- Diseases of the Developing World (DDW), GlaxoSmithKline, Severo Ochoa 2, Tres Cantos, 28760, Madrid, Spain
| | - Juliana Sanchez-Garcia
- In vivo Science & Delivery (IVSD), GlaxoSmithKline, Severo Ochoa 2, Tres Cantos, 28760, Madrid, Spain
| | - Jesús-Luís Presa Matilla
- Diseases of the Developing World (DDW), GlaxoSmithKline, Severo Ochoa 2, Tres Cantos, 28760, Madrid, Spain
| | - Didier Leroy
- Medicines for Malaria Venture, Route de Pré-Bois 20, 1215, Geneva 15, Switzerland
| | - Janneth Rodrigues
- Diseases of the Developing World (DDW), GlaxoSmithKline, Severo Ochoa 2, Tres Cantos, 28760, Madrid, Spain.
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Wadi I, Pillai CR, Anvikar AR, Sinha A, Nath M, Valecha N. Methylene blue induced morphological deformations in Plasmodium falciparum gametocytes: implications for transmission-blocking. Malar J 2018; 17:11. [PMID: 29310655 PMCID: PMC5759873 DOI: 10.1186/s12936-017-2153-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 12/23/2017] [Indexed: 12/24/2022] Open
Abstract
Background Malaria remains a global health problem despite availability of effective tools. For malaria elimination, drugs targeting sexual stages of Plasmodium falciparum need to be incorporated in treatment regimen along with schizonticidal drugs to interrupt transmission. Primaquine is recommended as a transmission blocking drug for its effect on mature gametocytes but is not extensively utilized because of associated safety concerns among glucose-6-phosphate dehydrogenase (G6PD) deficient patients. In present work, methylene blue, which is proposed as an alternative to primaquine is investigated for its gametocytocidal activity amongst Indian field isolates. An effort has been made to establish Indian field isolates of P. falciparum as in vitro model for gametocytocidal drugs screening. Methods Plasmodium falciparum isolates were adapted to in vitro culture and induced to gametocyte production by hypoxanthine and culture was enriched for gametocyte stages using N-acetyl-glucosamine. Gametocytes were incubated with methylene blue for 48 h and stage specific gametocytocidal activity was evaluated by microscopic examination. Results Plasmodium falciparum field isolates RKL-9 and JDP-8 were able to reproducibly produce gametocytes in high yield and were used to screen gametocytocidal drugs. Methylene blue was found to target gametocytes in a concentration dependent manner by either completely eliminating gametocytes or rendering them morphologically deformed with mean IC50 (early stages) as 424.1 nM and mean IC50 (late stages) as 106.4 nM. These morphologically altered gametocytes appeared highly degenerated having shrinkage, distortions and membrane deformations. Conclusions Field isolates that produce gametocytes in high yield in vitro can be identified and used to screen gametocytocidal drugs. These isolates should be used for validation of gametocytocidal hits obtained previously by using lab adapted reference strains. Methylene blue was found to target gametocytes produced from Indian field isolates and is proposed to be used as a gametocytocidal adjunct with artemisinin-based combination therapy. Further exploration of methylene blue in clinical studies amongst Indian population, including G6PD deficient patients, is recommended.
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Affiliation(s)
- Ishan Wadi
- Indian Council of Medical Research-National Institute of Malaria Research, Sector 8, Dwarka, New Delhi, 110077, India. .,Department of Chemistry, University of Delhi, Delhi, 110007, India.
| | - C Radhakrishna Pillai
- Indian Council of Medical Research-National Institute of Malaria Research, Sector 8, Dwarka, New Delhi, 110077, India
| | - Anupkumar R Anvikar
- Indian Council of Medical Research-National Institute of Malaria Research, Sector 8, Dwarka, New Delhi, 110077, India
| | - Abhinav Sinha
- Indian Council of Medical Research-National Institute of Malaria Research, Sector 8, Dwarka, New Delhi, 110077, India
| | - Mahendra Nath
- Department of Chemistry, University of Delhi, Delhi, 110007, India
| | - Neena Valecha
- Indian Council of Medical Research-National Institute of Malaria Research, Sector 8, Dwarka, New Delhi, 110077, India
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Okour M, Derimanov G, Barnett R, Fernandez E, Ferrer S, Gresham S, Hossain M, Gamo FJ, Koh G, Pereira A, Rolfe K, Wong D, Young G, Rami H, Haselden J. A human microdose study of the antimalarial drug GSK3191607 in healthy volunteers. Br J Clin Pharmacol 2017; 84:482-489. [PMID: 29168205 DOI: 10.1111/bcp.13476] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 10/07/2017] [Accepted: 11/14/2017] [Indexed: 01/03/2023] Open
Abstract
AIMS GSK3191607, a novel inhibitor of the Plasmodium falciparum ATP4 (PfATP4) pathway, is being considered for development in humans. However, a key problem encountered during the preclinical evaluation of the compound was its inconsistent pharmacokinetic (PK) profile across preclinical species (mouse, rat and dog), which prevented reliable prediction of PK parameters in humans and precluded a well-founded assessment of the potential for clinical development of the compound. Therefore, an open-label microdose (100 μg, six subjects) first time in humans study was conducted to assess the human PK of GSK3191607 following intravenous administration of [14C]-GSK3191607. METHODS A human microdose study was conducted to investigate the clinical PK of GSK3191607 and enable a Go/No Go decision on further progression of the compound. The PK disposition parameters estimated from the microdose study, combined with preclinical in vitro and in vivo pharmacodynamic parameters, were all used to estimate the potential efficacy of various oral dosing regimens in humans. RESULTS The PK profile, based on the microdose data, demonstrated a half-life (~17 h) similar to other antimalarial compounds currently in clinical development. However, combining the microdose data with the pharmacodynamic data provided results that do not support further clinical development of the compound for a single dose cure. CONCLUSIONS The information generated by this study provides a basis for predicting the expected oral PK profiles of GSK3191607 in man and supports decisions on the future clinical development of the compound.
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Affiliation(s)
- Malek Okour
- Clinical Pharmacology Modeling and Simulation (CPMS), GlaxoSmithKline, King of Prussia, PA, USA
| | - Geo Derimanov
- Discovery Medicine, Diseases of the Developing World, GlaxoSmithKline, Collegeville, PA, USA
| | - Rodger Barnett
- Drug Product Design and Development (DPDD), GlaxoSmithKline, Ware, Herts, UK
| | - Esther Fernandez
- Malaria DPU, Tres Cantos Medicines Development Campus, GlaxoSmithKline, Tres Cantos, Spain
| | - Santiago Ferrer
- Malaria DPU, Tres Cantos Medicines Development Campus, GlaxoSmithKline, Tres Cantos, Spain
| | | | - Mohammad Hossain
- Clinical Pharmacology Modeling and Simulation (CPMS), GlaxoSmithKline, King of Prussia, PA, USA
| | - Francisco-Javier Gamo
- Malaria DPU, Tres Cantos Medicines Development Campus, GlaxoSmithKline, Tres Cantos, Spain
| | - Gavin Koh
- Diseases of the Developing World, GlaxoSmithKline, Stockley Park, Uxbridge, UK
| | - Adrian Pereira
- Bioanalysis, Immunogenicity and Biomarkers (BIB), GlaxoSmithKline, Ware, UK
| | - Katie Rolfe
- Statistics, Programming and Data Strategy (SPDS), GlaxoSmithKline, Stockley Park, Uxbridge, UK
| | - Deborah Wong
- Clinical Pharmacology Science & Study Operations (CPSSO), GlaxoSmithKline, Stevenage, Hertfordshire, UK
| | - Graeme Young
- Bioanalysis, Immunogenicity and Biomarkers (BIB), GlaxoSmithKline, Ware, UK
| | - Harshad Rami
- Diseases of the Developing World, GlaxoSmithKline, Stockley Park, Uxbridge, UK
| | - John Haselden
- Malaria DPU, Tres Cantos Medicines Development Campus, GlaxoSmithKline, Tres Cantos, Spain
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In Vivo and In Vitro Activities and ADME-Tox Profile of a Quinolizidine-Modified 4-Aminoquinoline: A Potent Anti-P. falciparum and Anti-P. vivax Blood-Stage Antimalarial. Molecules 2017; 22:molecules22122102. [PMID: 29194347 PMCID: PMC6149971 DOI: 10.3390/molecules22122102] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 11/20/2017] [Accepted: 11/29/2017] [Indexed: 11/17/2022] Open
Abstract
Natural products are a prolific source for the identification of new biologically active compounds. In the present work, we studied the in vitro and in vivo antimalarial efficacy and ADME-Tox profile of a molecular hybrid (AM1) between 4-aminoquinoline and a quinolizidine moiety derived from lupinine (Lupinus luteus). The aim was to find a compound endowed with the target product profile-1 (TCP-1: molecules that clear asexual blood-stage parasitaemia), proposed by the Medicine for Malaria Venture to accomplish the goal of malaria elimination/eradication. AM1 displayed a very attractive profile in terms of both in vitro and in vivo activity. By using standard in vitro antimalarial assays, AM1 showed low nanomolar inhibitory activity against chloroquine-sensitive and resistant P. falciparum strains (range IC50 16–53 nM), matched with a high potency against P. vivax field isolates (Mean IC50 29 nM). Low toxicity and additivity with artemisinin derivatives were also demonstrated in vitro. High in vivo oral efficacy was observed in both P.berghei and P. yoelii mouse models with IC50 values comparable or better than those of chloroquine. The metabolic stability in different species and the pharmacokinetic profile in the mouse model makes AM1 a compound worth further investigation as a potential novel schizonticidal agent.
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Abstract
In the last 2 decades, renewed attention to neglected tropical diseases (NTDs) has spurred the development of antiparasitic agents, especially in light of emerging drug resistance. The need for new drugs has required in vitro screening methods using parasite culture. Furthermore, clinical laboratories sought to correlate in vitro susceptibility methods with treatment outcomes, most notably with malaria. Parasites with their various life cycles present greater complexity than bacteria, for which standardized susceptibility methods exist. This review catalogs the state-of-the-art methodologies used to evaluate the effects of drugs on key human parasites from the point of view of drug discovery as well as the need for laboratory methods that correlate with clinical outcomes.
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Abstract
Since the turn of the century, a remarkable expansion has been achieved in the range and effectiveness of products and strategies available to prevent, treat, and control malaria, including advances in diagnostics, drugs, vaccines, and vector control. These advances have once again put malaria elimination on the agenda. However, it is clear that even with the means available today, malaria control and elimination pose a formidable challenge in many settings. Thus, currently available resources must be used more effectively, and new products and approaches likely to achieve these goals must be developed. This paper considers tools (both those available and others that may be required) to achieve and maintain malaria elimination. New diagnostics are needed to direct treatment and detect transmission potential; new drugs and vaccines to overcome existing resistance and protect against clinical and severe disease, as well as block transmission and prevent relapses; and new vector control measures to overcome insecticide resistance and more powerfully interrupt transmission. It is also essential that strategies for combining new and existing approaches are developed for different settings to maximise their longevity and effectiveness in areas with continuing transmission and receptivity. For areas where local elimination has been recently achieved, understanding which measures are needed to maintain elimination is necessary to prevent rebound and the reestablishment of transmission. This becomes increasingly important as more countries move towards elimination.
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49
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Sinha S, Sarma P, Sehgal R, Medhi B. Development in Assay Methods for in Vitro Antimalarial Drug Efficacy Testing: A Systematic Review. Front Pharmacol 2017; 8:754. [PMID: 29123481 PMCID: PMC5662882 DOI: 10.3389/fphar.2017.00754] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 10/04/2017] [Indexed: 11/13/2022] Open
Abstract
The emergence and spread of drug resistance are the major challenges in malaria eradication mission. Besides various strategies laid down by World Health Organization, such as vector management, source reduction, early case detection, prompt treatment, and development of new diagnostics and vaccines, nevertheless the need for new and efficacious drugs against malaria has become a critical priority on the global malaria research agenda. At several screening stages, millions of compounds are screened (1,000–2,000,000 compounds per screening campaign), before pre-clinical trials to select optimum lead. Carrying out in vitro screening of antimalarials is very difficult as different assay methods are subject to numerous sources of variability across different laboratories around the globe. Despite this, in vitro screening is an essential part of antimalarial drug development as it enables to resource various confounding factors such as host immune response and drug–drug interaction. Therefore, in this article, we try to illustrate the basic necessity behind in vitro study and how new methods are developed and subsequently adopted for high-throughput antimalarial drug screening and its application in achieving the next level of in vitro screening based on the current approaches (such as stem cells).
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Affiliation(s)
- Shweta Sinha
- Department of Medical Parasitology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Phulen Sarma
- Department of Pharmacology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Rakesh Sehgal
- Department of Medical Parasitology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Bikash Medhi
- Department of Pharmacology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
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50
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Gebru T, Lalremruata A, Kremsner PG, Mordmüller B, Held J. Life-span of in vitro differentiated Plasmodium falciparum gametocytes. Malar J 2017; 16:330. [PMID: 28800735 PMCID: PMC5553604 DOI: 10.1186/s12936-017-1986-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 08/07/2017] [Indexed: 11/18/2022] Open
Abstract
Background The sexual stages (gametocytes) of Plasmodium falciparum do not directly contribute to the pathology of malaria but are essential for transmission of the parasite from the human host to the mosquito. Mature gametocytes circulate in infected human blood for several days and their circulation time has been modelled mathematically from data of previous in vivo studies. This is the first time that longevity of gametocytes is studied experimentally in vitro. Methods The in vitro longevity of P. falciparum gametocytes of 1 clinical isolate and 2 laboratory strains was assessed by three different methods: microscopy, flow cytometry and reverse transcription quantitative real-time PCR (RT-qPCR). Additionally, the rate of gametocytogenesis of the used P. falciparum strains was compared. Results The maximum in vitro lifespan of P. falciparum gametocytes reached almost 2 months (49 days by flow cytometry, 46 days by microscopy, and at least 52 days by RT-qPCR) from the starting day of gametocyte culture to death of last parasite in the tested strains with an average 50% survival rate of 6.5, 2.6 and 3.5 days, respectively. Peak gametocytaemia was observed on average 19 days after initiation of gametocyte culture followed by a steady decline due to natural decay of the parasites. The rate of gametocytogenesis was highest in the NF54 strain. Conclusions Plasmodium falciparum mature gametocytes can survive up to 16–32 days (at least 14 days for mature male gametocytes) in vitro in absence of the influence of host factors. This confirms experimentally a previous modelling estimate that used molecular tools for gametocyte detection in treated patients. The survival time might reflect the time the parasite can be transmitted to the mosquito after clearance of asexual parasites. These results underline the importance of efficient transmission blocking agents in the fight against malaria. Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-1986-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Tamirat Gebru
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.,German Centre for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany.,Department of Medical Laboratory Sciences, College of Medical and Health Sciences, Haramaya University, Harar, Ethiopia
| | - Albert Lalremruata
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.,German Centre for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
| | - Peter G Kremsner
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.,German Centre for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
| | - Benjamin Mordmüller
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.,German Centre for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
| | - Jana Held
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany. .,German Centre for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany.
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