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Annamalai Subramani P, Tipthara P, Kolli SK, Nicholas J, Barnes SJ, Ogbondah MM, Kobylinski KC, Tarning J, Adams JH. Efficacy of ivermectin and its metabolites against Plasmodium falciparum liver stages in primary human hepatocytes. Antimicrob Agents Chemother 2024; 68:e0127223. [PMID: 38904389 PMCID: PMC11304735 DOI: 10.1128/aac.01272-23] [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: 10/03/2023] [Accepted: 06/01/2024] [Indexed: 06/22/2024] Open
Abstract
Ivermectin, a broad-spectrum anti-parasitic drug, has been proposed as a novel vector control tool to reduce malaria transmission by mass drug administration. Ivermectin and some metabolites have mosquito-lethal effect, reducing Anopheles mosquito survival. Ivermectin inhibits liver stage development in a rodent malaria model, but no inhibition was observed in a primate malaria model or in a human malaria challenge trial. In the liver, cytochrome P450 3A4 and 3A5 enzymes metabolize ivermectin, which may impact drug efficacy. Thus, understanding ivermectin metabolism and assessing this impact on Plasmodium liver stage development is critical. Using primary human hepatocytes (PHHs), we characterized ivermectin metabolism and evaluated the efficacy of ivermectin and its primary metabolites M1 (3″-O-demethyl ivermectin) and M3 (4-hydroxymethyl ivermectin) against Plasmodium falciparum liver stages. Two different modes of ivermectin exposure were evaluated: prophylactic mode (days 0-3 post-infection) and curative mode (days 3-5 post-infection). We used two different PHH donors and modes to determine the inhibitory concentration (IC50) of ivermectin, M1, M3, and the known anti-malarial drug pyrimethamine, with IC50 values ranging from 1.391 to 14.44, 9.95-23.71, 4.767-8.384, and 0.9073-5.416 µM, respectively. In our PHH model, ivermectin and metabolites M1 and M3 demonstrated inhibitory activity against P. falciparum liver stages in curative treatment mode (days 3-5) and marginal activity in prophylactic treatment mode (days 0-3). Ivermectin had improved efficacy when co-administered with ketoconazole, a specific inhibitor of cytochrome P450 3A4 enzyme. Further studies should be performed to examine ivermectin liver stage efficacy when co-administered with CYP3A4 inhibitors and anti-malarial drugs to understand the pharmacokinetic and pharmacodynamic drug-drug interactions that enhance efficacy against human malaria parasites in vitro.
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Affiliation(s)
- Pradeep Annamalai Subramani
- Center for Global Health and Interdisciplinary Research, College of Public Health, University of South Florida, Tampa, Florida, USA
| | - Phornpimon Tipthara
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Surendra Kumar Kolli
- Center for Global Health and Interdisciplinary Research, College of Public Health, University of South Florida, Tampa, Florida, USA
| | - Justin Nicholas
- Center for Global Health and Interdisciplinary Research, College of Public Health, University of South Florida, Tampa, Florida, USA
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Samantha J. Barnes
- Center for Global Health and Interdisciplinary Research, College of Public Health, University of South Florida, Tampa, Florida, USA
| | - Madison M. Ogbondah
- Center for Global Health and Interdisciplinary Research, College of Public Health, University of South Florida, Tampa, Florida, USA
| | - Kevin C. Kobylinski
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Department of Entomology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Joel Tarning
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - John H. Adams
- Center for Global Health and Interdisciplinary Research, College of Public Health, University of South Florida, Tampa, Florida, USA
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2
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Liu R, Li G, Li M, Wang B, Zhang D, Xu L, Zhao L, Liao R, Xu Q, Bei ZC, Song Y. In vitro interaction of naphthoquine with ivermectin, atovaquone, curcumin, and ketotifen in the asexual blood stage of Plasmodium falciparum 3D7. Microbiol Spectr 2024; 12:e0063024. [PMID: 38780257 PMCID: PMC11218538 DOI: 10.1128/spectrum.00630-24] [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: 03/25/2024] [Accepted: 04/22/2024] [Indexed: 05/25/2024] Open
Abstract
Naphthoquine is a promising candidate for antimalarial combination therapy. Its combination with artemisinin has demonstrated excellent efficacy in clinical trials conducted across various malaria-endemic areas. A co-formulated combination of naphthoquine and azithromycin has also shown high clinical efficacy for malaria prophylaxis in Southeast Asia. Developing new combination therapies using naphthoquine will provide additional arsenal responses to the growing threat of artemisinin resistance. Furthermore, due to its long half-life, the possible interaction of naphthoquine with other drugs also needs attention. However, studies on its pharmacodynamic interactions with other drugs are still limited. In this study, the in vitro interactions of naphthoquine with ivermectin, atovaquone, curcumin, and ketotifen were evaluated in the asexual stage of Plasmodium falciparum 3D7. By using the combination index analysis and the SYBR Green I-based fluorescence assay, different interaction patterns of selected drugs with naphthoquine were revealed. Curcumin showed a slight but significant synergistic interaction with naphthoquine at lower effect levels, and no antagonism was observed across the full range of effect levels for all tested ratios. Atovaquone showed a potency decline when combined with naphthoquine. For ivermectin, a significant antagonism with naphthoquine was observed at a broad range of effect levels below 75% inhibition, although no significant interaction was observed at higher effect levels. Ketotifen interacted with naphthoquine similar to ivermectin, but significant antagonism was observed for only one tested ratio. These findings should be helpful to the development of new naphthoquine-based combination therapy and the clinically reasonable application of naphthoquine-containing therapies. IMPORTANCE Pharmacodynamic interaction between antimalarials is not only crucial for the development of new antimalarial combination therapies but also important for the appropriate clinical use of antimalarials. The significant synergism between curcumin and naphthoquine observed in this study suggests the potential value for further development of new antimalarial combination therapy. The finding of a decline in atovaquone potency in the presence of naphthoquine alerts to a possible risk of treatment or prophylaxis failure for atovaquone-proguanil following naphthoquine-containing therapies. The observation of antagonism between naphthoquine and ivermectin raised a need for concern about the applicability of naphthoquine-containing therapy in malaria-endemic areas with ivermectin mass drug administration deployed. Considering the role of atovaquone-proguanil as a major alternative when first-line artemisinin-based combination therapy is ineffective and the wide implementation of ivermectin mass drug administration in malaria-endemic countries, the above findings will be important for the appropriate clinical application of antimalarials involving naphthoquine-containing therapies.
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Affiliation(s)
- Ruotong Liu
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Guoming Li
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Mei Li
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Baogang Wang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Dongna Zhang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Likun Xu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Liangliang Zhao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Ruhe Liao
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Qin Xu
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Zhu-Chun Bei
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yabin Song
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
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3
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Johannsen S, Gierse RM, Krüger A, Edwards RL, Nanna V, Fontana A, Zhu D, Masini T, de Carvalho LP, Poizat M, Kieftenbelt B, Hodge DM, Alvarez S, Bunt D, Lacour A, Shams A, Meissner KA, de Souza EE, Dröge M, van Vliet B, den Hartog J, Hutter MC, Held J, Odom John AR, Wrenger C, Hirsch AKH. High Target Homology Does Not Guarantee Inhibition: Aminothiazoles Emerge as Inhibitors of Plasmodium falciparum. ACS Infect Dis 2024; 10:1000-1022. [PMID: 38367280 PMCID: PMC10928712 DOI: 10.1021/acsinfecdis.3c00670] [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: 12/06/2023] [Revised: 01/24/2024] [Accepted: 01/24/2024] [Indexed: 02/19/2024]
Abstract
In this study, we identified three novel compound classes with potent activity against Plasmodium falciparum, the most dangerous human malarial parasite. Resistance of this pathogen to known drugs is increasing, and compounds with different modes of action are urgently needed. One promising drug target is the enzyme 1-deoxy-d-xylulose-5-phosphate synthase (DXPS) of the methylerythritol 4-phosphate (MEP) pathway for which we have previously identified three active compound classes against Mycobacterium tuberculosis. The close structural similarities of the active sites of the DXPS enzymes of P. falciparum and M. tuberculosis prompted investigation of their antiparasitic action, all classes display good cell-based activity. Through structure-activity relationship studies, we increased their antimalarial potency and two classes also show good metabolic stability and low toxicity against human liver cells. The most active compound 1 inhibits the growth of blood-stage P. falciparum with an IC50 of 600 nM. The results from three different methods for target validation of compound 1 suggest no engagement of DXPS. All inhibitor classes are active against chloroquine-resistant strains, confirming a new mode of action that has to be further investigated.
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Affiliation(s)
- Sandra Johannsen
- Helmholtz
Institute for Pharmaceutical Research Saarland (HIPS) − Helmholtz
Centre for Infection Research (HZI), Campus Building E8.1, Saarbrücken 66123, Germany
- Department
of Pharmacy, Saarland University, Campus Building E8.1, Saarbrücken 66123, Germany
| | - Robin M. Gierse
- Helmholtz
Institute for Pharmaceutical Research Saarland (HIPS) − Helmholtz
Centre for Infection Research (HZI), Campus Building E8.1, Saarbrücken 66123, Germany
- Department
of Pharmacy, Saarland University, Campus Building E8.1, Saarbrücken 66123, Germany
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 7, Groningen 9747 AG, The Netherlands
| | - Arne Krüger
- Unit
for Drug Discovery, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1374, São Paulo-SP 05508-000, Brazil
| | - Rachel L. Edwards
- Department
of Pediatrics, Washington University School
of Medicine, Saint
Louis, Missouri 63110, United States
| | - Vittoria Nanna
- Helmholtz
Institute for Pharmaceutical Research Saarland (HIPS) − Helmholtz
Centre for Infection Research (HZI), Campus Building E8.1, Saarbrücken 66123, Germany
| | - Anna Fontana
- Helmholtz
Institute for Pharmaceutical Research Saarland (HIPS) − Helmholtz
Centre for Infection Research (HZI), Campus Building E8.1, Saarbrücken 66123, Germany
| | - Di Zhu
- Helmholtz
Institute for Pharmaceutical Research Saarland (HIPS) − Helmholtz
Centre for Infection Research (HZI), Campus Building E8.1, Saarbrücken 66123, Germany
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 7, Groningen 9747 AG, The Netherlands
| | - Tiziana Masini
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 7, Groningen 9747 AG, The Netherlands
| | | | - Mael Poizat
- Symeres, Kadijk 3, Groningen 9747
AT, The Netherlands
| | | | - Dana M. Hodge
- Department
of Pediatrics, Children’s Hospital
of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Sophie Alvarez
- Proteomics
& Metabolomics Facility, Center for Biotechnology, Department
of Agronomy and Horticulture, University
of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
| | - Daan Bunt
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 7, Groningen 9747 AG, The Netherlands
| | - Antoine Lacour
- Helmholtz
Institute for Pharmaceutical Research Saarland (HIPS) − Helmholtz
Centre for Infection Research (HZI), Campus Building E8.1, Saarbrücken 66123, Germany
- Department
of Pharmacy, Saarland University, Campus Building E8.1, Saarbrücken 66123, Germany
| | - Atanaz Shams
- Helmholtz
Institute for Pharmaceutical Research Saarland (HIPS) − Helmholtz
Centre for Infection Research (HZI), Campus Building E8.1, Saarbrücken 66123, Germany
- Department
of Pharmacy, Saarland University, Campus Building E8.1, Saarbrücken 66123, Germany
| | - Kamila Anna Meissner
- Unit
for Drug Discovery, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1374, São Paulo-SP 05508-000, Brazil
| | - Edmarcia Elisa de Souza
- Unit
for Drug Discovery, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1374, São Paulo-SP 05508-000, Brazil
| | | | | | | | - Michael C. Hutter
- Center
for Bioinformatics, Saarland University, Campus Building E2.1, Saarbrücken 66123, Germany
| | - Jana Held
- Institute
of Tropical Medicine, University of Tübingen, Wilhelmstraße 27, Tübingen 72074, Germany
- German
Center for Infection Research (DZIF), Partner Site Tübingen, Tübingen 72074, Germany
- Centre
de Recherches Médicales de Lambaréné (CERMEL), B.P. 242 Lambaréné, Gabon
| | - Audrey R. Odom John
- Department
of Pediatrics, Children’s Hospital
of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Carsten Wrenger
- Unit
for Drug Discovery, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1374, São Paulo-SP 05508-000, Brazil
| | - Anna K. H. Hirsch
- Helmholtz
Institute for Pharmaceutical Research Saarland (HIPS) − Helmholtz
Centre for Infection Research (HZI), Campus Building E8.1, Saarbrücken 66123, Germany
- Department
of Pharmacy, Saarland University, Campus Building E8.1, Saarbrücken 66123, Germany
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 7, Groningen 9747 AG, The Netherlands
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Ekoka Mbassi D, Mombo-Ngoma G, Held J, Okwu DG, Ndzebe-Ndoumba W, Kalkman LC, Ekoka Mbassi FA, Pessanha de Carvalho L, Inoue J, Akinosho MA, Dimessa Mbadinga LB, Yovo EK, Mordmüller B, Kremsner PG, Adegnika AA, Ramharter M, Zoleko-Manego R. Efficacy and safety of ivermectin for the treatment of Plasmodium falciparum infections in asymptomatic male and female Gabonese adults - a pilot randomized, double-blind, placebo-controlled single-centre phase Ib/IIa clinical trial. EBioMedicine 2023; 97:104814. [PMID: 37839134 PMCID: PMC10582777 DOI: 10.1016/j.ebiom.2023.104814] [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: 03/31/2023] [Revised: 08/21/2023] [Accepted: 09/15/2023] [Indexed: 10/17/2023] Open
Abstract
BACKGROUND Ivermectin's mosquitocidal effect and in vitro activity against Plasmodium falciparum asexual stages are known. Its in vivo blood-schizonticidal efficacy is unknown. Ivermectin's tolerability and efficacy against P. falciparum infections in Gabonese adults were assessed. METHODS The study consisted of a multiple dose stage and a randomized, double-blind, placebo-controlled stage. Adults with asymptomatic P. falciparum parasitaemia (200-5000 parasites/μl) were enrolled. First, three groups of five participants received 200 μg/kg ivermectin once daily for one, two, and three days, respectively, and then 34 participants were randomized to 300 μg/kg ivermectin or placebo once daily for 3 days. Primary efficacy outcome was time to 90% parasite reduction. Primary safety outcomes were drug-related serious and severe adverse events (Trial registration: PACTR201908520097051). FINDINGS Between June 2019 and October 2020, 49 participants were enrolled. Out of the 34 randomized participants, 29 (85%) completed the trial as per protocol. No severe or serious adverse events were observed. The median time to 90% parasite reduction was 24.1 vs. 32.0 h in the ivermectin and placebo groups, respectively (HR 1.38 [95% CI 0.64 to 2.97]). INTERPRETATION Ivermectin was well tolerated in doses up to 300 μg/kg once daily for three days and asymptomatic P. falciparum asexual parasitaemia was reduced similarly with this dose of ivermectin compared to placebo. Further studies are needed to evaluate plasmodicidal effect of ivermectin at higher doses and in larger samples. FUNDING This study was funded by the Centre de Recherches Médicales de Lambaréné and the Centre for Tropical Medicine of the Bernhard Nocht Institute for Tropical Medicine.
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Affiliation(s)
- Dorothea Ekoka Mbassi
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon; Centre for Tropical Medicine, Bernhard Nocht Institute for Tropical Medicine & I. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; German Center for Infection Research (DZIF), Partner Site Hamburg-Borstel-Lübeck-Riems, Germany
| | - Ghyslain Mombo-Ngoma
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon; German Center for Infection Research (DZIF), Partner Site Hamburg-Borstel-Lübeck-Riems, Germany; Department of Implementation Research, Bernhard Nocht Institute for Tropical Medicine & I. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Jana Held
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany; German Center for Infection Research (DZIF), Partner Site Tübingen, Tübingen, Germany
| | - Dearie Glory Okwu
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon; Department of Implementation Research, Bernhard Nocht Institute for Tropical Medicine & I. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Wilfrid Ndzebe-Ndoumba
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon; Department of Implementation Research, Bernhard Nocht Institute for Tropical Medicine & I. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | | | - Franck Aurelien Ekoka Mbassi
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon; Centre for Tropical Medicine, Bernhard Nocht Institute for Tropical Medicine & I. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; German Center for Infection Research (DZIF), Partner Site Hamburg-Borstel-Lübeck-Riems, Germany
| | | | - Juliana Inoue
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
| | | | | | | | - Benjamin Mordmüller
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany; Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - Peter Gottfried Kremsner
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon; Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany; German Center for Infection Research (DZIF), Partner Site Tübingen, Tübingen, Germany
| | - Ayôla Akim Adegnika
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon; Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany; German Center for Infection Research (DZIF), Partner Site Tübingen, Tübingen, Germany; Department of Parasitology, Leiden University Medical Centre (LUMC), 2333 ZA, Leiden, the Netherlands; Fondation pour la Recherche Scientifique, 72 BP45, Cotonou, Benin
| | - Michael Ramharter
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon; Centre for Tropical Medicine, Bernhard Nocht Institute for Tropical Medicine & I. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; German Center for Infection Research (DZIF), Partner Site Hamburg-Borstel-Lübeck-Riems, Germany
| | - Rella Zoleko-Manego
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon; Centre for Tropical Medicine, Bernhard Nocht Institute for Tropical Medicine & I. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; German Center for Infection Research (DZIF), Partner Site Hamburg-Borstel-Lübeck-Riems, Germany; Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.
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5
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de Carvalho LP, Niepoth E, Mavraj-Husejni A, Kreidenweiss A, Herrmann J, Müller R, Knaab T, Burckhardt BB, Kurz T, Held J. Quantification of Plasmodium falciparum HRP-2 as an alternative method to [ 3H]hypoxanthine incorporation to measure the parasite reduction ratio in vitro. Int J Antimicrob Agents 2023; 62:106894. [PMID: 37348620 DOI: 10.1016/j.ijantimicag.2023.106894] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 06/06/2023] [Accepted: 06/10/2023] [Indexed: 06/24/2023]
Abstract
In the absence of a highly efficacious vaccine, chemotherapy remains the cornerstone to control malaria morbidity and mortality. The threat of the emergence of parasites resistant to artemisinin-based combination therapies highlights the need for new antimalarial drugs ideally with superior properties. The killing rate reflects the speed of action of antimalarial drugs, which can be measured in vitro through the parasite reduction ratio (PRR) assay to shortlist interesting candidates. As a standard, the in vitro PRR assay is performed by measuring [3H]hypoxanthine incorporation of Plasmodium falciparum. This methodology is restricted to specialised laboratories owing to the handling of radioactive material. In this work, we describe a sandwich enzyme-linked immunosorbent assay to detect P. falciparum histidine-rich protein 2 (HRP-2) as an alternative methodology to assess the PRR. We first validated the methodology with established antimalarial drugs (artesunate, chloroquine, pyrimethamine and atovaquone) by comparing our results with previous results of the [3H]hypoxanthine incorporation readout provided by an expert laboratory, and subsequently assessed the speed of action of four new antimalarial candidates (compound 22, chlorotonil A, boromycin and ivermectin). The HRP-2 PRR assay achieved comparable results to the [3H]hypoxanthine incorporation readout in terms of parasite growth rate over time, lag phase and parasite clearance time. In addition, parasite growth following drug exposure was quantified after 7, 14, 21 and 28 days of recovery time. In conclusion, the PRR assay based on HRP-2 is similar to [3H]hypoxanthine in determining a drug's parasite killing rate and can be widely used in all research laboratories.
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Affiliation(s)
| | - Elena Niepoth
- 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), Braunschweig, Germany
| | - Jennifer Herrmann
- German Center for Infection Research (DZIF), Braunschweig, Germany; Helmholtz Institute for Pharmaceutical Research Saarland, Saarbrücken, Germany
| | - Rolf Müller
- German Center for Infection Research (DZIF), Braunschweig, Germany; Helmholtz Institute for Pharmaceutical Research Saarland, Saarbrücken, Germany
| | - Tanja Knaab
- Institute of Pharmaceutics and Biopharmaceutics, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Bjoern B Burckhardt
- Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Münster, Germany
| | - Thomas Kurz
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - 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), Braunschweig, Germany.
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6
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Yipsirimetee A, Tipthara P, Hanboonkunupakarn B, Tripura R, Lek D, Kümpornsin K, Lee MCS, Sattabongkot J, Dondorp AM, White NJ, Kobylinski KC, Tarning J, Chotivanich K. Activity of Ivermectin and Its Metabolites against Asexual Blood Stage Plasmodium falciparum and Its Interactions with Antimalarial Drugs. Antimicrob Agents Chemother 2023; 67:e0173022. [PMID: 37338381 PMCID: PMC10368210 DOI: 10.1128/aac.01730-22] [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: 12/29/2022] [Accepted: 05/12/2023] [Indexed: 06/21/2023] Open
Abstract
Ivermectin is an endectocide used widely to treat a variety of internal and external parasites. Field trials of ivermectin mass drug administration for malaria transmission control have demonstrated a reduction of Anopheles mosquito survival and human malaria incidence. Ivermectin will mostly be deployed together with artemisinin-based combination therapies (ACT), the first-line treatment of falciparum malaria. It has not been well established if ivermectin has activity against asexual stage Plasmodium falciparum or if it interacts with the parasiticidal activity of other antimalarial drugs. This study evaluated antimalarial activity of ivermectin and its metabolites in artemisinin-sensitive and artemisinin-resistant P. falciparum isolates and assessed in vitro drug-drug interaction with artemisinins and its partner drugs. The concentration of ivermectin causing half of the maximum inhibitory activity (IC50) on parasite survival was 0.81 μM with no significant difference between artemisinin-sensitive and artemisinin-resistant isolates (P = 0.574). The ivermectin metabolites were 2-fold to 4-fold less active than the ivermectin parent compound (P < 0.001). Potential pharmacodynamic drug-drug interactions of ivermectin with artemisinins, ACT-partner drugs, and atovaquone were studied in vitro using mixture assays providing isobolograms and derived fractional inhibitory concentrations. There were no synergistic or antagonistic pharmacodynamic interactions when combining ivermectin and antimalarial drugs. In conclusion, ivermectin does not have clinically relevant activity against the asexual blood stages of P. falciparum. It also does not affect the in vitro antimalarial activity of artemisinins or ACT-partner drugs against asexual blood stages of P. falciparum.
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Affiliation(s)
- Achaporn Yipsirimetee
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Phornpimon Tipthara
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Borimas Hanboonkunupakarn
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Rupam Tripura
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Dysoley Lek
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Krittikorn Kümpornsin
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, United Kingdom
- Calibr, Division of the Scripps Research Institute, La Jolla, California, USA
| | - Marcus C. S. Lee
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, United Kingdom
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Arjen M. Dondorp
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Nicholas J. White
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Kevin C. Kobylinski
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Department of Entomology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Joel Tarning
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Kesinee Chotivanich
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
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7
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Walunj SB, Wang C, Wagstaff KM, Patankar S, Jans DA. Conservation of Importin α Function in Apicomplexans: Ivermectin and GW5074 Target Plasmodium falciparum Importin α and Inhibit Parasite Growth in Culture. Int J Mol Sci 2022; 23:ijms232213899. [PMID: 36430384 PMCID: PMC9695642 DOI: 10.3390/ijms232213899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 11/03/2022] [Accepted: 11/08/2022] [Indexed: 11/16/2022] Open
Abstract
Signal-dependent transport into and out of the nucleus mediated by members of the importin (IMP) superfamily of nuclear transporters is critical to the eukaryotic function and a point of therapeutic intervention with the potential to limit disease progression and pathogenic outcomes. Although the apicomplexan parasites Plasmodium falciparum and Toxoplasma gondii both retain unique IMPα genes that are essential, a detailed analysis of their properties has not been performed. As a first step to validate apicomplexan IMPα as a target, we set out to compare the properties of P. falciparum and T. gondii IMPα (PfIMPα and TgIMPα, respectively) to those of mammalian IMPα, as exemplified by Mus musculus IMPα (MmIMPα). Close similarities were evident, with all three showing high-affinity binding to modular nuclear localisation signals (NLSs) from apicomplexans as well as Simian virus SV40 large tumour antigen (T-ag). PfIMPα and TgIMPα were also capable of binding to mammalian IMPβ1 (MmIMPβ1) with high affinity; strikingly, NLS binding by PfIMPα and TgIMPα could be inhibited by the mammalian IMPα targeting small molecules ivermectin and GW5074 through direct binding to PfIMPα and TgIMPα to perturb the α-helical structure. Importantly, GW5074 could be shown for the first time to resemble ivermectin in being able to limit growth of P. falciparum. The results confirm apicomplexan IMPα as a viable target for the development of therapeutics, with agents targeting it worthy of further consideration as an antimalarial.
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Affiliation(s)
- Sujata B. Walunj
- Molecular Parasitology Lab., Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
- Nuclear Signalling Lab., Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Monash, VIC 3800, Australia
| | - Chunxiao Wang
- Nuclear Signalling Lab., Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Monash, VIC 3800, Australia
| | - Kylie M. Wagstaff
- Nuclear Signalling Lab., Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Monash, VIC 3800, Australia
| | - Swati Patankar
- Molecular Parasitology Lab., Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - David A. Jans
- Nuclear Signalling Lab., Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Monash, VIC 3800, Australia
- Correspondence:
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8
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Fraccaroli L, Ruiz MD, Perdomo VG, Clausi AN, Balcazar DE, Larocca L, Carrillo C. Broadening the spectrum of ivermectin: Its effect on Trypanosoma cruzi and related trypanosomatids. Front Cell Infect Microbiol 2022; 12:885268. [PMID: 35967842 PMCID: PMC9366347 DOI: 10.3389/fcimb.2022.885268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Accepted: 07/05/2022] [Indexed: 11/22/2022] Open
Abstract
Chagas disease is an endemic American parasitosis, caused by Trypanosoma cruzi. The current therapies, benznidazole (BZN) and nifurtimox (NFX), show limited efficacy and multiple side effects. Thus, there is a need to develop new trypanocidal strategies. Ivermectin (IVM) is a broad-spectrum antiparasitic drug with low human and veterinary toxicity with effects against T. brucei and Leishmania spp. Considering this and its relatively low cost, we evaluate IVM as a potential repurposed trypanocidal drug on T. cruzi and other trypanosomatids. We found that IVM affected, in a dose-dependent manner, the proliferation of T. cruzi epimastigotes as well as the amastigotes and trypomastigotes survival. The Selectivity Index for the amastigote stage with respect to Vero cells was 12. The IVM effect was also observed in Phytomonas jma 066 and Leishmania mexicana proliferation but not in Crithidia fasciculata. On the epimastigote stage, the IVM effect was trypanostatic at 50 μM but trypanocidal at 100 μM. The assays of the drug combinations of IVM with BNZ or NFX showed mainly additive effects among combinations. In silico studies showed that classical structures belonging to glutamate-gated Cl channels, the most common IVM target, are absent in kinetoplastids. However, we found in the studied trypanosomatid genomes one copy for putative IMPα and IMPβ, potential targets for IVM. The putative IMPα genes (with 76% similarity) showed conserved Armadillo domains but lacked the canonical IMPβ binding sequence. These results allowed us to propose a novel molecular target in T. cruzi and suggest IVM as a good candidate for drug repurposing in the Chagas disease context.
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Affiliation(s)
- Laura Fraccaroli
- Laboratorio de Biología Molecular y Bioquímica en Trypanosoma cruzi y otros agentes infecciosos, CONICET for Instituto de Ciencia y Tecnología (ICT) Milstein - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Buenos Aires, Argentina
- *Correspondence: Laura Fraccaroli, ; Carolina Carrillo,
| | - María Daniela Ruiz
- Laboratorio de Biología Molecular y Bioquímica en Trypanosoma cruzi y otros agentes infecciosos, CONICET for Instituto de Ciencia y Tecnología (ICT) Milstein - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Buenos Aires, Argentina
| | - Virginia Gabriela Perdomo
- Área Parasitología, Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Rosario, Argentina
| | - Agustina Nicole Clausi
- Laboratorio de Biología Molecular y Bioquímica en Trypanosoma cruzi y otros agentes infecciosos, CONICET for Instituto de Ciencia y Tecnología (ICT) Milstein - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Buenos Aires, Argentina
| | - Darío Emmanuel Balcazar
- Área Parasitología, Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Rosario, Argentina
| | - Luciana Larocca
- Laboratorio de Biología Molecular y Bioquímica en Trypanosoma cruzi y otros agentes infecciosos, CONICET for Instituto de Ciencia y Tecnología (ICT) Milstein - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Buenos Aires, Argentina
| | - Carolina Carrillo
- Laboratorio de Biología Molecular y Bioquímica en Trypanosoma cruzi y otros agentes infecciosos, CONICET for Instituto de Ciencia y Tecnología (ICT) Milstein - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Buenos Aires, Argentina
- *Correspondence: Laura Fraccaroli, ; Carolina Carrillo,
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9
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von Bredow L, Schäfer TM, Hogenkamp J, Tretbar M, Stopper D, Kraft FB, Schliehe-Diecks J, Schöler A, Borkhardt A, Bhatia S, Held J, Hansen FK. Synthesis, Antiplasmodial, and Antileukemia Activity of Dihydroartemisinin–HDAC Inhibitor Hybrids as Multitarget Drugs. Pharmaceuticals (Basel) 2022; 15:ph15030333. [PMID: 35337131 PMCID: PMC8952208 DOI: 10.3390/ph15030333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 02/24/2022] [Accepted: 03/01/2022] [Indexed: 02/04/2023] Open
Abstract
Artemisinin-based combination therapies (ACTs) are the gold standard for the treatment of malaria, but the efficacy is threatened by the development of parasite resistance. Histone deacetylase inhibitors (HDACis) are an emerging new class of potential antiplasmodial drugs. In this work, we present the design, synthesis, and biological evaluation of a mini library of dihydroartemisinin–HDACi hybrid molecules. The screening of the hybrid molecules for their activity against selected human HDAC isoforms, asexual blood stage P. falciparum parasites, and a panel of leukemia cell lines delivered important structure–activity relationships. All synthesized compounds demonstrated potent activity against the 3D7 and Dd2 line of P. falciparum with IC50 values in the single-digit nanomolar range. Furthermore, the hybrid (α)-7c displayed improved activity against artemisinin-resistant parasites compared to dihydroartemisinin. The screening of the compounds against five cell lines from different leukemia entities revealed that all hydroxamate-based hybrids (7a–e) and the ortho-aminoanilide 8 exceeded the antiproliferative activity of dihydroartemisinin in four out of five cell lines. Taken together, this series of hybrid molecules represents an excellent starting point toward the development of antimalarial and antileukemia drug leads.
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Affiliation(s)
- Lukas von Bredow
- Medical Faculty, Institute for Drug Discovery, Leipzig University, 04103 Leipzig, Germany; (L.v.B.); (M.T.); (A.S.)
| | - Thomas Martin Schäfer
- Institut für Tropenmedizin, Eberhard Karls Universität Tübingen, 72074 Tübingen, Germany; (T.M.S.); (J.H.)
| | - Julian Hogenkamp
- Department of Pediatric Oncology, Hematology and Clinical Immunology, Medical Faculty, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany; (J.H.); (J.S.-D.); (A.B.); (S.B.)
| | - Maik Tretbar
- Medical Faculty, Institute for Drug Discovery, Leipzig University, 04103 Leipzig, Germany; (L.v.B.); (M.T.); (A.S.)
| | - Daniel Stopper
- Department of Pharmaceutical and Cell Biological Chemistry, Pharmaceutical Institute, University of Bonn, 53121 Bonn, Germany; (D.S.); (F.B.K.)
| | - Fabian B. Kraft
- Department of Pharmaceutical and Cell Biological Chemistry, Pharmaceutical Institute, University of Bonn, 53121 Bonn, Germany; (D.S.); (F.B.K.)
| | - Julian Schliehe-Diecks
- Department of Pediatric Oncology, Hematology and Clinical Immunology, Medical Faculty, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany; (J.H.); (J.S.-D.); (A.B.); (S.B.)
| | - Andrea Schöler
- Medical Faculty, Institute for Drug Discovery, Leipzig University, 04103 Leipzig, Germany; (L.v.B.); (M.T.); (A.S.)
| | - Arndt Borkhardt
- Department of Pediatric Oncology, Hematology and Clinical Immunology, Medical Faculty, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany; (J.H.); (J.S.-D.); (A.B.); (S.B.)
| | - Sanil Bhatia
- Department of Pediatric Oncology, Hematology and Clinical Immunology, Medical Faculty, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany; (J.H.); (J.S.-D.); (A.B.); (S.B.)
| | - Jana Held
- Institut für Tropenmedizin, Eberhard Karls Universität Tübingen, 72074 Tübingen, Germany; (T.M.S.); (J.H.)
- German Center for Infection Research (DZIF), Partner Site Tübingen, 72074 Tübingen, Germany
| | - Finn K. Hansen
- Department of Pharmaceutical and Cell Biological Chemistry, Pharmaceutical Institute, University of Bonn, 53121 Bonn, Germany; (D.S.); (F.B.K.)
- Correspondence:
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10
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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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11
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Synthesis and antiplasmodial activity of regioisomers and epimers of second-generation dual acting ivermectin hybrids. Sci Rep 2022; 12:564. [PMID: 35022455 PMCID: PMC8755717 DOI: 10.1038/s41598-021-04532-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 12/23/2021] [Indexed: 12/15/2022] Open
Abstract
With its strong effect on vector-borne diseases, and insecticidal effect on mosquito vectors of malaria, inhibition of sporogonic and blood-stage development of Plasmodium falciparum, as well as in vitro and in vivo impairment of the P. berghei development inside hepatocytes, ivermectin (IVM) continues to represent an antimalarial therapeutic worthy of investigation. The in vitro activity of the first-generation IVM hybrids synthesized by appending the IVM macrolide with heterocyclic and organometallic antimalarial pharmacophores, against the blood-stage and liver-stage infections by Plasmodium parasites prompted us to design second-generation molecular hybrids of IVM. Here, a structural modification of IVM to produce novel molecular hybrids by using sub-structures of 4- and 8-aminoquinolines, the time-tested antiplasmodial agents used for treating the blood and hepatic stage of Plasmodium infections, respectively, is presented. Successful isolation of regioisomers and epimers has been demonstrated, and the evaluation of their in vitro antiplasmodial activity against both the blood stages of P. falciparum and the hepatic stages of P. berghei have been undertaken. These compounds displayed structure-dependent antiplasmodial activity, in the nM range, which was more potent than that of IVM, its aglycon or primaquine, highlighting the superiority of this hybridization strategy in designing new antiplasmodial agents.
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12
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Endo T, Takemae H, Sharma I, Furuya T. Multipurpose Drugs Active Against Both Plasmodium spp. and Microorganisms: Potential Application for New Drug Development. Front Cell Infect Microbiol 2021; 11:797509. [PMID: 35004357 PMCID: PMC8740689 DOI: 10.3389/fcimb.2021.797509] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 12/01/2021] [Indexed: 12/29/2022] Open
Abstract
Malaria, a disease caused by the protozoan parasites Plasmodium spp., is still causing serious problems in endemic regions in the world. Although the WHO recommends artemisinin combination therapies for the treatment of malaria patients, the emergence of artemisinin-resistant parasites has become a serious issue and underscores the need for the development of new antimalarial drugs. On the other hand, new and re-emergences of infectious diseases, such as the influenza pandemic, Ebola virus disease, and COVID-19, are urging the world to develop effective chemotherapeutic agents against the causative viruses, which are not achieved to the desired level yet. In this review article, we describe existing drugs which are active against both Plasmodium spp. and microorganisms including viruses, bacteria, and fungi. We also focus on the current knowledge about the mechanism of actions of these drugs. Our major aims of this article are to describe examples of drugs that kill both Plasmodium parasites and other microbes and to provide valuable information to help find new ideas for developing novel drugs, rather than merely augmenting already existing drug repurposing efforts.
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Affiliation(s)
- Takuro Endo
- Laboratory of Veterinary Infectious Diseases, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Hitoshi Takemae
- Center for Infectious Disease Epidemiology and Prevention Research, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Indu Sharma
- Department of Biological Sciences, Hampton University, Hampton, VA, United States
| | - Tetsuya Furuya
- Laboratory of Veterinary Infectious Diseases, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan
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13
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The antimicrobial and immunomodulatory effects of Ionophores for the treatment of human infection. J Inorg Biochem 2021; 227:111661. [PMID: 34896767 DOI: 10.1016/j.jinorgbio.2021.111661] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 10/27/2021] [Accepted: 11/03/2021] [Indexed: 12/18/2022]
Abstract
Ionophores are a diverse class of synthetic and naturally occurring ion transporter compounds which demonstrate both direct and in-direct antimicrobial properties against a broad panel of bacterial, fungal, viral and parasitic pathogens. In addition, ionophores can regulate the host-immune response during communicable and non-communicable disease states. Although the clinical use of ionophores such as Amphotericin B, Bedaquiline and Ivermectin highlight the utility of ionophores in modern medicine, for many other ionophore compounds issues surrounding toxicity, bioavailability or lack of in vivo efficacy studies have hindered clinical development. The antimicrobial and immunomodulating properties of a range of compounds with characteristics of ionophores remain largely unexplored. As such, ionophores remain a latent therapeutic avenue to address both the global burden of antimicrobial resistance, and the unmet clinical need for new antimicrobial therapies. This review will provide an overview of the broad-spectrum antimicrobial and immunomodulatory properties of ionophores, and their potential uses in clinical medicine for combatting infection.
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14
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Singh L, Singh K. Ivermectin: A Promising Therapeutic for Fighting Malaria. Current Status and Perspective. J Med Chem 2021; 64:9711-9731. [PMID: 34242031 DOI: 10.1021/acs.jmedchem.1c00498] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Finding new chemotherapeutic interventions to treat malaria through repurposing of time-tested drugs and rigorous design of new drugs using tools of rational drug design remains one of the most sought strategies at the disposal of medicinal chemists. Ivermectin, a semisynthetic derivative of avermectin B1, is among the efficacious drugs used in mass drug administration drives employed against onchocerciasis, lymphatic filariasis, and several other parasitic diseases in humans. In this review, we present the prowess of ivermectin, a potent endectocide, in the control of malaria through vector control to reduce parasite transmission combined with efficacious chemoprevention to reduce malaria-related fatalities.
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Affiliation(s)
- Lovepreet Singh
- Department of Chemistry, UGC Centre for Advanced Studies-II, Guru Nanak Dev University, Amritsar-143 005, India
| | - Kamaljit Singh
- Department of Chemistry, UGC Centre for Advanced Studies-II, Guru Nanak Dev University, Amritsar-143 005, India
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15
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Pessanha de Carvalho L, Kreidenweiss A, Held J. Drug Repurposing: A Review of Old and New Antibiotics for the Treatment of Malaria: Identifying Antibiotics with a Fast Onset of Antiplasmodial Action. Molecules 2021; 26:2304. [PMID: 33921170 PMCID: PMC8071546 DOI: 10.3390/molecules26082304] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 04/12/2021] [Accepted: 04/13/2021] [Indexed: 11/24/2022] Open
Abstract
Malaria is one of the most life-threatening infectious diseases and constitutes a major health problem, especially in Africa. Although artemisinin combination therapies remain efficacious to treat malaria, the emergence of resistant parasites emphasizes the urgent need of new alternative chemotherapies. One strategy is the repurposing of existing drugs. Herein, we reviewed the antimalarial effects of marketed antibiotics, and described in detail the fast-acting antibiotics that showed activity in nanomolar concentrations. Antibiotics have been used for prophylaxis and treatment of malaria for many years and are of particular interest because they might exert a different mode of action than current antimalarials, and can be used simultaneously to treat concomitant bacterial infections.
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Affiliation(s)
- Lais Pessanha de Carvalho
- Institute of Tropical Medicine, University of Tuebingen, 72074 Tuebingen, Germany; (L.P.d.C.); (A.K.)
| | - Andrea Kreidenweiss
- Institute of Tropical Medicine, University of Tuebingen, 72074 Tuebingen, Germany; (L.P.d.C.); (A.K.)
- Centre de Recherches Medicales de Lambaréné (CERMEL), Lambaréné BP 242, Gabon
| | - Jana Held
- Institute of Tropical Medicine, University of Tuebingen, 72074 Tuebingen, Germany; (L.P.d.C.); (A.K.)
- Centre de Recherches Medicales de Lambaréné (CERMEL), Lambaréné BP 242, Gabon
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16
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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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El-Saber Batiha G, Alqahtani A, Ilesanmi OB, Saati AA, El-Mleeh A, Hetta HF, Magdy Beshbishy A. Avermectin Derivatives, Pharmacokinetics, Therapeutic and Toxic Dosages, Mechanism of Action, and Their Biological Effects. Pharmaceuticals (Basel) 2020; 13:E196. [PMID: 32824399 PMCID: PMC7464486 DOI: 10.3390/ph13080196] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 08/09/2020] [Accepted: 08/13/2020] [Indexed: 12/15/2022] Open
Abstract
Avermectins are a group of drugs that occurs naturally as a product of fermenting Streptomyces avermitilis, an actinomycetes, isolated from the soil. Eight different structures, including ivermectin, abamectin, doramectin, eprinomectin, moxidectin, and selamectin, were isolated and divided into four major components (A1a, A2a, B1a and B2a) and four minor components (A1b, A2b, B1b, and B2b). Avermectins are generally used as a pesticide for the treatment of pests and parasitic worms as a result of their anthelmintic and insecticidal properties. Additionally, they possess anticancer, anti-diabetic, antiviral, antifungal, and are used for treatment of several metabolic disorders. Avermectin generally works by preventing the transmission of electrical impulse in the muscle and nerves of invertebrates, by amplifying the glutamate effects on the invertebrates-specific gated chloride channel. Avermectin has unwanted effects or reactions, especially when administered indiscriminately, which include respiratory failure, hypotension, and coma. The current review examines the mechanism of actions, biosynthesis, safety, pharmacokinetics, biological toxicity and activities of avermectins.
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Affiliation(s)
- Gaber El-Saber Batiha
- Department of Pharmacology and Therapeutics, Faculty of Veterinary Medicine, Damanhour University, Damanhour 22511, Egypt
| | - Ali Alqahtani
- Department of Pharmacology, College of Pharmacy, King Khalid University, Guraiger, Abha 62529, Saudi Arabia;
| | - Omotayo B. Ilesanmi
- Department of Biochemistry, Faculty of Science, Federal University Otuoke, Otuoke 561, Nigeria;
| | - Abdullah A. Saati
- Department of Community Medicine & Pilgrims Healthcare, Faculty of Medicine, Umm Al-Qura University Makkah, Mecca 24382, Saudi Arabia;
| | - Amany El-Mleeh
- Department of Pharmacology, Faculty of Veterinary Medicine, Menoufia University, Shibin Al Kawm 32511, Egypt;
| | - Helal F. Hetta
- Department of Medical Microbiology and Immunology, Faculty of Medicine, Assiut University, Assiut 71515, Egypt;
- Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45221, USA
| | - Amany Magdy Beshbishy
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Nishi 2-13, Inada-cho, Obihiro 080-8555, Hokkaido, Japan
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Repurposing Drugs to Fight Hepatic Malaria Parasites. Molecules 2020; 25:molecules25153409. [PMID: 32731386 PMCID: PMC7435416 DOI: 10.3390/molecules25153409] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/23/2020] [Accepted: 07/24/2020] [Indexed: 12/16/2022] Open
Abstract
Malaria remains one of the most prevalent infectious diseases worldwide, primarily affecting some of the most vulnerable populations around the globe. Despite achievements in the treatment of this devastating disease, there is still an urgent need for the discovery of new drugs that tackle infection by Plasmodium parasites. However, de novo drug development is a costly and time-consuming process. An alternative strategy is to evaluate the anti-plasmodial activity of compounds that are already approved for other purposes, an approach known as drug repurposing. Here, we will review efforts to assess the anti-plasmodial activity of existing drugs, with an emphasis on the obligatory and clinically silent liver stage of infection. We will also review the current knowledge on the classes of compounds that might be therapeutically relevant against Plasmodium in the context of other communicable diseases that are prevalent in regions where malaria is endemic. Repositioning existing compounds may constitute a faster solution to the current gap of prophylactic and therapeutic drugs that act on Plasmodium parasites, overall contributing to the global effort of malaria eradication.
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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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Nodari R, Corbett Y, Varotto-Boccazzi I, Porretta D, Taramelli D, Epis S, Bandi C. Effects of combined drug treatments on Plasmodium falciparum: In vitro assays with doxycycline, ivermectin and efflux pump inhibitors. PLoS One 2020; 15:e0232171. [PMID: 32324826 PMCID: PMC7179878 DOI: 10.1371/journal.pone.0232171] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 04/08/2020] [Indexed: 12/15/2022] Open
Abstract
There is great concern regarding the rapid emergence and spread of drug-resistance in Plasmodium falciparum, the parasite responsible for the most severe form of human malaria. Parasite populations resistant to some or all the currently available antimalarial treatments are present in different world regions. Considering the need for novel and integrated approaches to control malaria, combinations of drugs were tested on P. falciparum. The primary focus was on doxycycline, an antibiotic that specifically targets the apicoplast of the parasite. In combination with doxycycline, three different drugs known to inhibit efflux pumps (verapamil, elacridar and ivermectin) were tested, with the assumption that they could increase the intracellular concentration of the antibiotic and consequently its efficacy against P. falciparum. We emphasize that elacridar is a third-generation ABC transporters inhibitor, never tested before on malaria parasites. In vitro experiments were performed on asexual stages of two strains of P. falciparum, chloroquine-sensitive (D10) and chloroquine-resistant (W2). Incubation times on asynchronous or synchronous cultures were 72h or 96h, respectively. The antiplasmodial effect (i.e. the IC50) was determined by measuring the activity of the parasite lactate dehydrogenase, while the interaction between drugs was determined through combination index (CI) analyses. Elacridar achieved an IC50 concentration comparable to that of ivermectin, approx. 10-fold lower than that of verapamil, the other tested ABC transporter inhibitor. CI results showed synergistic effect of verapamil plus doxycycline, which is coherent with the starting hypothesis, i.e. that ABC transporters represent potential targets, worth of further investigations, towards the development of companion molecules useful to enhance the efficacy of antimalarial drugs. At the same time, the observed antagonistic effect of doxycycline in combination with ivermectin or elacridar highlighted the importance of drug testing, to avoid the de-facto generation of a sub-dosage, a condition that facilitates the development of drug resistance.
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Affiliation(s)
- Riccardo Nodari
- Department of Biosciences and Pediatric Clinical Research Center Romeo ed Enrica Invernizzi, University of Milan, Milan, Italy
- Centro Interuniversitario di Ricerca sulla Malaria/Italian Malaria Network, Milan, Italy
| | - Yolanda Corbett
- Department of Biosciences and Pediatric Clinical Research Center Romeo ed Enrica Invernizzi, University of Milan, Milan, Italy
- Centro Interuniversitario di Ricerca sulla Malaria/Italian Malaria Network, Milan, Italy
| | - Ilaria Varotto-Boccazzi
- Department of Biosciences and Pediatric Clinical Research Center Romeo ed Enrica Invernizzi, University of Milan, Milan, Italy
- Centro Interuniversitario di Ricerca sulla Malaria/Italian Malaria Network, Milan, Italy
| | - Daniele Porretta
- Department of Environmental Biology, Sapienza University of Rome, Rome, Italy
| | - Donatella Taramelli
- Centro Interuniversitario di Ricerca sulla Malaria/Italian Malaria Network, Milan, Italy
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan, Italy
| | - Sara Epis
- Department of Biosciences and Pediatric Clinical Research Center Romeo ed Enrica Invernizzi, University of Milan, Milan, Italy
- Centro Interuniversitario di Ricerca sulla Malaria/Italian Malaria Network, Milan, Italy
| | - Claudio Bandi
- Department of Biosciences and Pediatric Clinical Research Center Romeo ed Enrica Invernizzi, University of Milan, Milan, Italy
- Centro Interuniversitario di Ricerca sulla Malaria/Italian Malaria Network, Milan, Italy
- * E-mail:
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21
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Billingsley P, Binka F, Chaccour C, Foy B, Gold S, Gonzalez-Silva M, Jacobson J, Jagoe G, Jones C, Kachur P, Kobylinski K, Last A, Lavery JV, Mabey D, Mboera D, Mbogo C, Mendez-Lopez A, Rabinovich NR, Rees S, Richards F, Rist C, Rockwood J, Ruiz-Castillo P, Sattabongkot J, Saute F, Slater H, Steer A, Xia K, Zullinger R. A Roadmap for the Development of Ivermectin as a Complementary Malaria Vector Control Tool. Am J Trop Med Hyg 2020; 102:3-24. [PMID: 31971144 PMCID: PMC7008306 DOI: 10.4269/ajtmh.19-0620] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 10/22/2019] [Indexed: 12/14/2022] Open
Abstract
In the context of stalling progress against malaria, resistance of mosquitoes to insecticides, and residual transmission, mass drug administration (MDA) of ivermectin, an endectocide used for neglected tropical diseases (NTDs), has emerged as a promising complementary vector control method. Ivermectin reduces the life span of Anopheles mosquitoes that feed on treated humans and/or livestock, potentially decreasing malaria parasite transmission when administered at the community level. Following the publication by WHO of the preferred product characteristics for endectocides as vector control tools, this roadmap provides a comprehensive view of processes needed to make ivermectin available as a vector control tool by 2024 with a completely novel mechanism of action. The roadmap covers various aspects, which include 1) the definition of optimal dosage/regimens for ivermectin MDA in both humans and livestock, 2) the risk of resistance to the drug and environmental impact, 3) ethical issues, 4) political and community engagement, 5) translation of evidence into policy, and 6) operational aspects of large-scale deployment of the drug, all in the context of a drug given as a prevention tool acting at the community level. The roadmap reflects the insights of a multidisciplinary group of global health experts who worked together to elucidate the path to inclusion of ivermectin in the toolbox against malaria, to address residual transmission, counteract insecticide resistance, and contribute to the end of this deadly disease.
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Affiliation(s)
| | - Fred Binka
- University of Health and Allied Sciences
| | | | | | | | | | | | | | | | | | | | - Anna Last
- London School of Hygiene and Tropical Medicine
| | | | - David Mabey
- London School of Hygiene and Tropical Medicine
| | | | | | | | | | | | | | - Cassidy Rist
- Virginia-Maryland College of Veterinary Medicine at Virginia Tech
| | | | | | | | | | | | | | - Kang Xia
- School of Plant and Environmental Sciences, Virginia Tech
| | - Rose Zullinger
- US President’s Malaria Initiative/US Centers for Disease Control and Prevention
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Azevedo R, Mendes AM, Prudêncio M. Inhibition of Plasmodium sporogonic stages by ivermectin and other avermectins. Parasit Vectors 2019; 12:549. [PMID: 31752986 PMCID: PMC6873674 DOI: 10.1186/s13071-019-3805-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 11/12/2019] [Indexed: 12/15/2022] Open
Abstract
Background The transmissible forms of Plasmodium parasites result from a process of sporogony that takes place inside their obligatory mosquito vector and culminates in the formation of mammalian-infective parasite forms. Ivermectin is a member of the avermectin family of endectocides, which has been proposed to inhibit malaria transmission due its insecticidal effect. However, it remains unclear whether ivermectin also exerts a direct action on the parasite’s blood and transmission stages. Methods We employed a rodent model of infection to assess the impact of ivermectin treatment on P. berghei asexual and sexual blood forms in vivo. We then made use of a newly established luminescence-based methodology to evaluate the activity of ivermectin and other avermectins against the sporogonic stages of P. berghei parasites in vitro independent of their role on mosquito physiology. Results Our results show that whereas ivermectin does not affect the parasite’s parasitemia, gametocytemia or exflagellation in the mammalian host, several members of the avermectin family of compounds exert a strong inhibitory effect on the generation and development of P. berghei oocysts. Conclusions Our results shed light on the action of avermectins against Plasmodium transmission stages and highlight the potential of these compounds to help prevent the spread of malaria.
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Affiliation(s)
- Raquel Azevedo
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028, Lisbon, Portugal
| | - António M Mendes
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028, Lisbon, Portugal.
| | - Miguel Prudêncio
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028, Lisbon, Portugal.
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