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Amengor CDK, Biniyam PD, Brobbey AA, Kekessie FK, Zoiku FK, Hamidu S, Gyan P, Abudey BM. N-Substituted Phenylhydrazones Kill the Ring Stage of Plasmodium falciparum. BIOMED RESEARCH INTERNATIONAL 2024; 2024:6697728. [PMID: 38380127 PMCID: PMC10878751 DOI: 10.1155/2024/6697728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 01/11/2024] [Accepted: 01/18/2024] [Indexed: 02/22/2024]
Abstract
Antimalarial resistance has hampered the effective treatment of malaria, a parasitic disease caused by Plasmodium species. As part of our campaign on phenotypic screening of phenylhydrazones, a library of six phenylhydrazones was reconstructed and evaluated for their in vitro antimalarial and in silico receptor binding and pharmacokinetic properties. The structures of the phenylhydrazone hybrids were largely confirmed using nuclear magnetic resonance techniques. We identified two compounds which exhibited significant antimalarial potential against the ring stage (trophozoite) of 3D7 chloroquine-sensitive (CS) strain and DD2 chloroquine-resistant (CR) strains of Plasmodium falciparum with monosubstituted analogs bearing meta or para electron-donating groups showing significant activity in the single-digit micromolar range. Structure activity relationship is presented showing that electron-donating groups on the substituent hydrophobic pharmacophore are required for antimalarial activity. Compounds PHN6 and PHN3 were found to be the most potent with pIC50s (calculated form in vitro IC50s) of 5.37 and 5.18 against 3D7 CS and DD2 CR strains, respectively. Our selected ligands (PHN3 and PHN6) performed better when compared to chloroquine regarding binding affinity and molecular stability with the regulatory proteins of Plasmodium falciparum, hence predicted to be largely responsible for their in vitro activity. Pharmacokinetic prediction demonstrated that the phenylhydrazones may not cross the blood-brain barrier and are not P-glycoprotein (P-gp) substrates, a good absorption of 62% to 69%, and classified as a category IV compound based on toxicity grading.
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Affiliation(s)
| | - Prince Danan Biniyam
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of Health and Allied Sciences, Ho, Ghana
| | - Abena Amponsaa Brobbey
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Francis Klenam Kekessie
- Department of Chemistry and Biochemistry, The University of Southern Mississippi, Hattiesburg Campus, 118 College Drive, Hattiesburg, USA
| | - Felix Kwame Zoiku
- Department of Epidemiology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P.O. Box LG 581, Legon, Accra, Ghana
| | - Sherif Hamidu
- Department of Clinical Pathology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P.O. Box LG 581, Legon, Accra, Ghana
| | - Patrick Gyan
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of Health and Allied Sciences, Ho, Ghana
| | - Billy Mawunyo Abudey
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of Health and Allied Sciences, Ho, Ghana
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2
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Umumararungu T, Nkuranga JB, Habarurema G, Nyandwi JB, Mukazayire MJ, Mukiza J, Muganga R, Hahirwa I, Mpenda M, Katembezi AN, Olawode EO, Kayitare E, Kayumba PC. Recent developments in antimalarial drug discovery. Bioorg Med Chem 2023; 88-89:117339. [PMID: 37236020 DOI: 10.1016/j.bmc.2023.117339] [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: 03/01/2023] [Revised: 05/12/2023] [Accepted: 05/16/2023] [Indexed: 05/28/2023]
Abstract
Although malaria remains a big burden to many countries that it threatens their socio-economic stability, particularly in the countries where malaria is endemic, there have been great efforts to eradicate this disease with both successes and failures. For example, there has been a great improvement in malaria prevention and treatment methods with a net reduction in infection and mortality rates. However, the disease remains a global threat in terms of the number of people affected because it is one of the infectious diseases that has the highest prevalence rate, especially in Africa where the deadly Plasmodium falciparum is still widely spread. Methods to fight malaria are being diversified, including the use of mosquito nets, the target candidate profiles (TCPs) and target product profiles (TPPs) of medicine for malarial venture (MMV) strategy, the search for newer and potent drugs that could reverse chloroquine resistance, and the use of adjuvants such as rosiglitazone and sevuparin. Although these adjuvants have no antiplasmodial activity, they can help to alleviate the effects which result from plasmodium invasion such as cytoadherence. The list of new antimalarial drugs under development is long, including the out of ordinary new drugs MMV048, CDRI-97/78 and INE963 from South Africa, India and Novartis, respectively.
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Affiliation(s)
- Théoneste Umumararungu
- Department of Pharmacy, School of Medicine and Pharmacy, College of Medicine and Health Sciences, University of Rwanda, Rwanda.
| | - Jean Bosco Nkuranga
- Department of Chemistry, School of Science, College of Science and Technology, University of Rwanda, Rwanda
| | - Gratien Habarurema
- Department of Chemistry, School of Science, College of Science and Technology, University of Rwanda, Rwanda
| | - Jean Baptiste Nyandwi
- Department of Pharmacy, School of Medicine and Pharmacy, College of Medicine and Health Sciences, University of Rwanda, Rwanda
| | - Marie Jeanne Mukazayire
- Department of Pharmacy, School of Medicine and Pharmacy, College of Medicine and Health Sciences, University of Rwanda, Rwanda
| | - Janvier Mukiza
- Department of Mathematical Science and Physical Education, School of Education, College of Education, University of Rwanda, Rwanda; Rwanda Food and Drugs Authority, Nyarutarama Plaza, KG 9 Avenue, Kigali, Rwanda
| | - Raymond Muganga
- Department of Pharmacy, School of Medicine and Pharmacy, College of Medicine and Health Sciences, University of Rwanda, Rwanda; Rwanda Food and Drugs Authority, Nyarutarama Plaza, KG 9 Avenue, Kigali, Rwanda
| | - Innocent Hahirwa
- Department of Pharmacy, School of Medicine and Pharmacy, College of Medicine and Health Sciences, University of Rwanda, Rwanda
| | - Matabishi Mpenda
- Department of Pharmacy, School of Medicine and Pharmacy, College of Medicine and Health Sciences, University of Rwanda, Rwanda
| | - Alain Nyirimigabo Katembezi
- Department of Pharmacy, School of Medicine and Pharmacy, College of Medicine and Health Sciences, University of Rwanda, Rwanda; Rwanda Food and Drugs Authority, Nyarutarama Plaza, KG 9 Avenue, Kigali, Rwanda
| | - Emmanuel Oladayo Olawode
- Department of Pharmaceutical Sciences, College of Pharmacy, Larkin University, 18301 N Miami Ave #1, Miami, FL 33169, USA
| | - Egide Kayitare
- Department of Pharmacy, School of Medicine and Pharmacy, College of Medicine and Health Sciences, University of Rwanda, Rwanda
| | - Pierre Claver Kayumba
- Department of Pharmacy, School of Medicine and Pharmacy, College of Medicine and Health Sciences, University of Rwanda, Rwanda
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3
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Gansane A, Lingani M, Yeka A, Nahum A, Bouyou-Akotet M, Mombo-Ngoma G, Kaguthi G, Barceló C, Laurijssens B, Cantalloube C, Macintyre F, Djeriou E, Jessel A, Bejuit R, Demarest H, Marrast AC, Debe S, Tinto H, Kibuuka A, Nahum D, Mawili-Mboumba DP, Zoleko-Manego R, Mugenya I, Olewe F, Duparc S, Ogutu B. Randomized, open-label, phase 2a study to evaluate the contribution of artefenomel to the clinical and parasiticidal activity of artefenomel plus ferroquine in African patients with uncomplicated Plasmodium falciparum malaria. Malar J 2023; 22:2. [PMID: 36597076 PMCID: PMC9809015 DOI: 10.1186/s12936-022-04420-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 12/16/2022] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND The contribution of artefenomel to the clinical and parasiticidal activity of ferroquine and artefenomel in combination in uncomplicated Plasmodium falciparum malaria was investigated. METHODS This Phase 2a, randomized, open-label, parallel-group study was conducted from 11th September 2018 to 6th November 2019 across seven centres in Benin, Burkina Faso, Gabon, Kenya, and Uganda. Patients aged ≥ 14-69 years with microscopically confirmed infection (≥ 3000 to ≤ 50,000 parasites/µL blood) were randomized 1:1:1:1 to 400 mg ferroquine, or 400 mg ferroquine plus artefenomel 300, 600, or 1000 mg, administered as a single oral dose. The primary efficacy analysis was a logistic regression evaluating the contribution of artefenomel exposure to Day 28 PCR-adjusted adequate clinical and parasitological response (ACPR). Safety was also evaluated. RESULTS The randomized population included 140 patients. For the primary analysis in the pharmacokinetic/pharmacodynamic efficacy population (N = 121), the contribution of artefenomel AUC0-∞ to Day 28 PCR-adjusted ACPR was not demonstrated when accounting for ferroquine AUC0-d28, baseline parasitaemia, and other model covariates: odds ratio 1.1 (95% CI 0.98, 1.2; P = 0.245). In the per-protocol population, Day 28 PCR-adjusted ACPR was 80.8% (21/26; 95% CI 60.6, 93.4) with ferroquine alone and 90.3% (28/31; 95% CI 74.2, 98.0), 90.9% (30/33; 95% CI 75.7, 98.1) and 87.1% (27/31; 95% CI 70.2, 96.4) with 300, 600, and 1000 mg artefenomel, respectively. Median time to parasite clearance (Kaplan-Meier) was 56.1 h with ferroquine, more rapid with artefenomel, but similar for all doses (30.0 h). There were no deaths. Adverse events (AEs) of any cause occurred in 51.4% (18/35) of patients with ferroquine 400 mg alone, and 58.3% (21/36), 66.7% (24/36), and 72.7% (24/33) with 300, 600, and 1000 mg artefenomel, respectively. All AEs were of mild-to-moderate severity, and consistent with the known profiles of the compounds. Vomiting was the most reported AE. There were no cases of QTcF prolongation ≥ 500 ms or > 60 ms from baseline. CONCLUSION The contribution of artefenomel exposure to the clinical and parasitological activity of ferroquine/artefenomel could not be demonstrated in this study. Parasite clearance was faster with ferroquine/artefenomel versus ferroquine alone. All treatments were well tolerated. TRIAL REGISTRATION ClinicalTrials.gov, NCT03660839 (7 September, 2018).
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Affiliation(s)
- Adama Gansane
- grid.507461.10000 0004 0413 3193Centre National de Recherche et de Formation sur le Paludisme (CNRFP), 01 BP 220801 BP 2208 Ouagadougou, Burkina Faso
| | - Moussa Lingani
- grid.457337.10000 0004 0564 0509Institut de Recherche en Science de la Santé - Unité de Recherche Clinique de Nanoro (IRSS-URCN), Ouagadougou, Burkina Faso
| | - Adoke Yeka
- grid.463352.50000 0004 8340 3103Infectious Diseases Research Collaboration (IDRC), Kampala, Uganda
| | - Alain Nahum
- Centre de Recherches Entomologique de Cotonou (CREC), Cotonou, Benin
| | - Marielle Bouyou-Akotet
- grid.502965.dDépartement de Parasitologie-Mycologie-Médecine Tropicale, Faculté de Médecine – Université des Sciences de la Santé, Libreville, Gabon
| | - Ghyslain Mombo-Ngoma
- grid.452268.fCentre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon ,Department of Tropical Medicine, Bernhard Nocht Institute for Tropical Medicine, and University Medical Center Hamburg-Eppendorf, Hamburg, Germany ,grid.10392.390000 0001 2190 1447Institute for Tropical Medicine, University of Tübingen, Tübingen, Germany
| | - Grace Kaguthi
- grid.33058.3d0000 0001 0155 5938Kenya Medical Research Institute-Centre for Respiratory Diseases Research (KEMRI-CRDR), Nairobi, Kenya
| | - Catalina Barceló
- grid.452605.00000 0004 0432 5267Medicines for Malaria Venture, Geneva, Switzerland
| | | | | | - Fiona Macintyre
- grid.452605.00000 0004 0432 5267Medicines for Malaria Venture, Geneva, Switzerland
| | | | | | | | - Helen Demarest
- grid.452605.00000 0004 0432 5267Medicines for Malaria Venture, Geneva, Switzerland
| | - Anne Claire Marrast
- grid.452605.00000 0004 0432 5267Medicines for Malaria Venture, Geneva, Switzerland
| | - Siaka Debe
- grid.507461.10000 0004 0413 3193Centre National de Recherche et de Formation sur le Paludisme (CNRFP), 01 BP 220801 BP 2208 Ouagadougou, Burkina Faso
| | - Halidou Tinto
- grid.457337.10000 0004 0564 0509Institut de Recherche en Science de la Santé - Unité de Recherche Clinique de Nanoro (IRSS-URCN), Ouagadougou, Burkina Faso
| | - Afizi Kibuuka
- grid.463352.50000 0004 8340 3103Infectious Diseases Research Collaboration (IDRC), Kampala, Uganda
| | - Diolinda Nahum
- Centre de Recherches Entomologique de Cotonou (CREC), Cotonou, Benin
| | - Denise Patricia Mawili-Mboumba
- grid.502965.dDépartement de Parasitologie-Mycologie-Médecine Tropicale, Faculté de Médecine – Université des Sciences de la Santé, Libreville, Gabon
| | - Rella Zoleko-Manego
- grid.452268.fCentre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon ,Department of Tropical Medicine, Bernhard Nocht Institute for Tropical Medicine, and University Medical Center Hamburg-Eppendorf, Hamburg, Germany ,grid.10392.390000 0001 2190 1447Institute for Tropical Medicine, University of Tübingen, Tübingen, Germany
| | - Irene Mugenya
- grid.33058.3d0000 0001 0155 5938Kenya Medical Research Institute-Centre for Respiratory Diseases Research (KEMRI-CRDR), Nairobi, Kenya
| | - Frederick Olewe
- grid.33058.3d0000 0001 0155 5938Centre for Clinical Research, Kenya Medical Research Institute, Kisumu, Kenya ,grid.442494.b0000 0000 9430 1509Centre for Research in Therapeutic Sciences (CREATES), Strathmore University, Nairobi, Kenya
| | - Stephan Duparc
- grid.452605.00000 0004 0432 5267Medicines for Malaria Venture, Geneva, Switzerland
| | - Bernhards Ogutu
- grid.33058.3d0000 0001 0155 5938Centre for Clinical Research, Kenya Medical Research Institute, Kisumu, Kenya ,grid.442494.b0000 0000 9430 1509Centre for Research in Therapeutic Sciences (CREATES), Strathmore University, Nairobi, Kenya
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4
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Ng JPL, Han Y, Yang LJ, Birkholtz LM, Coertzen D, Wong HN, Haynes RK, Coghi P, Wong VKW. Antimalarial and antitumour activities of the steroidal quinone-methide celastrol and its combinations with artemiside, artemisone and methylene blue. Front Pharmacol 2022; 13:988748. [PMID: 36120293 PMCID: PMC9479156 DOI: 10.3389/fphar.2022.988748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 08/08/2022] [Indexed: 11/19/2022] Open
Abstract
Artemisinin, isolated from the traditional Chinese medicinal plant qīng hāo 青蒿 (Artemisia annua) and its derivatives are used for treatment of malaria. With treatment failures now being recorded for the derivatives and companion drugs used in artemisinin combination therapies new drug combinations are urgently required. The amino-artemisinins artemiside and artemisone display optimal efficacies in vitro against asexual and sexual blood stages of the malaria parasite Plasmodium falciparum and are active against tumour cell lines. In continuing the evolution of combinations of the amino-artemisinins with new drugs, we examine the triterpenoid quinone methide celastrol isolated from the traditional Chinese medicinal plant léi gōng téng 雷公藤 (Tripterygium wilfordii). This compound is redox active, and has attracted considerable attention because of potent biological activities against manifold targets. We report that celastrol displays good IC50 activities ranging from 0.50–0.82 µM against drug-sensitive and resistant asexual blood stage Pf, and 1.16 and 0.28 µM respectively against immature and late stage Pf NF54 gametocytes. The combinations of celastrol with each of artemisone and methylene blue against asexual blood stage Pf are additive. Given that celastrol displays promising antitumour properties, we examined its activities alone and in combinations with amino-artemisinins against human liver HepG2 and other cell lines. IC50 values of the amino-artemisinins and celastrol against HepG2 cancer cells ranged from 0.55–0.94 µM. Whereas the amino-artemisinins displayed notable selectivities (SI > 171) with respect to normal human hepatocytes, in contrast, celastrol displayed no selectivity (SI < 1). The combinations of celastrol with artemiside or artemisone against HepG2 cells are synergistic. Given the promise of celastrol, judiciously designed formulations or structural modifications are recommended for mitigating its toxicity.
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Affiliation(s)
- Jerome P. L. Ng
- Neher’s Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Macau, China
| | - Yu Han
- Neher’s Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Macau, China
| | - Li Jun Yang
- Neher’s Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Macau, China
| | - Lyn-Marie Birkholtz
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria Institute Malaria for Sustainable Malaria Control, University of Pretoria, Hatfield, South Africa
| | - Dina Coertzen
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria Institute Malaria for Sustainable Malaria Control, University of Pretoria, Hatfield, South Africa
| | - Ho Ning Wong
- Centre of Excellence for Pharmaceutical Sciences, School of Health Sciences, North-West University, Potchefstroom, South Africa
| | - Richard K. Haynes
- Centre of Excellence for Pharmaceutical Sciences, School of Health Sciences, North-West University, Potchefstroom, South Africa
- *Correspondence: Richard K. Haynes, Paolo Coghi, Vincent Kam Wai Wong,
| | - Paolo Coghi
- School of Pharmacy, Macau University of Science and Technology, Macau, China
- *Correspondence: Richard K. Haynes, Paolo Coghi, Vincent Kam Wai Wong,
| | - Vincent Kam Wai Wong
- Neher’s Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Macau, China
- *Correspondence: Richard K. Haynes, Paolo Coghi, Vincent Kam Wai Wong,
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5
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Yang J, Wang Y, Guan W, Su W, Li G, Zhang S, Yao H. Spiral molecules with antimalarial activities: A review. Eur J Med Chem 2022; 237:114361. [DOI: 10.1016/j.ejmech.2022.114361] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 04/03/2022] [Accepted: 04/04/2022] [Indexed: 11/04/2022]
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6
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Siddiqui G, Giannangelo C, De Paoli A, Schuh AK, Heimsch KC, Anderson D, Brown TG, MacRaild CA, Wu J, Wang X, Dong Y, Vennerstrom JL, Becker K, Creek DJ. Peroxide Antimalarial Drugs Target Redox Homeostasis in Plasmodium falciparum Infected Red Blood Cells. ACS Infect Dis 2022; 8:210-226. [PMID: 34985858 PMCID: PMC8762662 DOI: 10.1021/acsinfecdis.1c00550] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
![]()
Plasmodium
falciparum causes the
most lethal form of malaria. Peroxide antimalarials based on artemisinin
underpin the frontline treatments for malaria, but artemisinin resistance
is rapidly spreading. Synthetic peroxide antimalarials, known as ozonides,
are in clinical development and offer a potential alternative. Here,
we used chemoproteomics to investigate the protein alkylation targets
of artemisinin and ozonide probes, including an analogue of the ozonide
clinical candidate, artefenomel. We greatly expanded the list of proteins
alkylated by peroxide antimalarials and identified significant enrichment
of redox-related proteins for both artemisinins and ozonides. Disrupted
redox homeostasis was confirmed by dynamic live imaging of the glutathione
redox potential using a genetically encoded redox-sensitive fluorescence-based
biosensor. Targeted liquid chromatography-mass spectrometry (LC-MS)-based
thiol metabolomics also confirmed changes in cellular thiol levels.
This work shows that peroxide antimalarials disproportionately alkylate
proteins involved in redox homeostasis and that disrupted redox processes
are involved in the mechanism of action of these important antimalarials.
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Affiliation(s)
- Ghizal Siddiqui
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Carlo Giannangelo
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Amanda De Paoli
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Anna Katharina Schuh
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University Giessen, 35392 Giessen, Germany
| | - Kim C. Heimsch
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University Giessen, 35392 Giessen, Germany
| | - Dovile Anderson
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Timothy G. Brown
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Christopher A. MacRaild
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Jianbo Wu
- College of Pharmacy, University of Nebraska Medical Center, 986125 Nebraska Medical Center, Omaha, Nebraska 68198-6125, United States
| | - Xiaofang Wang
- College of Pharmacy, University of Nebraska Medical Center, 986125 Nebraska Medical Center, Omaha, Nebraska 68198-6125, United States
| | - Yuxiang Dong
- College of Pharmacy, University of Nebraska Medical Center, 986125 Nebraska Medical Center, Omaha, Nebraska 68198-6125, United States
| | - Jonathan L. Vennerstrom
- College of Pharmacy, University of Nebraska Medical Center, 986125 Nebraska Medical Center, Omaha, Nebraska 68198-6125, United States
| | - Katja Becker
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University Giessen, 35392 Giessen, Germany
| | - Darren J. Creek
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
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7
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Wittlin S, Mäser P. From Magic Bullet to Magic Bomb: Reductive Bioactivation of Antiparasitic Agents. ACS Infect Dis 2021; 7:2777-2786. [PMID: 34472830 DOI: 10.1021/acsinfecdis.1c00118] [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] [Indexed: 11/30/2022]
Abstract
Paul Ehrlich coined the term "magic bullet" to describe how a drug kills the parasite inside its human host without harming the host itself. Ehrlich concluded that the drug must have a greater affinity to the parasite than to human cells. Today, the specificity of drug action is understood in terms of the drug target. An ideal target is a protein that is essential for the proliferation of the pathogen but absent in human cells. Examples are the enzymes of folate synthesis or of the nonmevalonate pathway in the malaria parasites. However, there are other ways how a drug can kill selectively. Of particular relevance is the specific activation of a prodrug inside the pathogen but not in the host, as this is how the current frontrunners of parasite chemotherapy work. Artemisinins for malaria, fexinidazole for human African trypanosomiasis, benznidazole for Chagas' disease, metronidazole for intestinal protozoa: these molecules are "magic bombs" that are triggered selectively. They are prodrugs that need to be activated by chemical reduction, i.e., the acquisition of an electron, which occurs in the parasite. Such a mode of action is shared by the novel antimalarial peroxides arterolane and artefenomel, which are activated by reduction of the endoperoxide bond with ferrous heme as the likely electron donor, a metabolic end-product of Plasmodium falciparum. Here we provide an overview on the molecular basis of selectivity of antiparasitic drug action with particular reference to the ozonides, the new generation of antimalarial peroxides designed by Jonathan Vennerstrom.
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Affiliation(s)
- Sergio Wittlin
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, 4051 Basel, Switzerland
- University of Basel, 4001 Basel, Switzerland
| | - Pascal Mäser
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, 4051 Basel, Switzerland
- University of Basel, 4001 Basel, Switzerland
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8
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Zech J, Salaymeh N, Hunt NH, Mäder K, Golenser J. Efficient Treatment of Experimental Cerebral Malaria by an Artemisone-SMEDDS System: Impact of Application Route and Dosing Frequency. Antimicrob Agents Chemother 2021; 65:e02106-20. [PMID: 33558284 PMCID: PMC8097435 DOI: 10.1128/aac.02106-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 01/28/2021] [Indexed: 11/24/2022] Open
Abstract
Artemisone (ART) has been successfully tested in vitro and in animal models against several diseases. However, its poor aqueous solubility and limited chemical stability are serious challenges. We developed a self-microemulsifying drug delivery system (SMEDDS) that overcomes these limitations. Here, we demonstrate the efficacy of this formulation against experimental cerebral malaria in mice and the impact of its administration using different routes (gavage, intranasal delivery, and parenteral injections) and frequency on the efficacy of the treatment. The minimal effective daily oral dose was 20 mg/kg. We found that splitting a dose of 20 mg/kg ART given every 24 h, by administering two doses of 10 mg/kg each every 12 h, was highly effective and gave far superior results compared to 20 mg/kg once daily. We obtained the best results with nasal treatment; oral treatment was ranked second, and the least effective route of administration was intraperitoneal injection. A complete cure of experimental cerebral malaria could be achieved through choosing the optimal route of application, dose, and dosing interval. Altogether, the developed formulation combines easy manufacturing with high stability and could be a successful and very versatile carrier for the delivery of ART in the treatment of human severe malaria.
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Affiliation(s)
- Johanna Zech
- Institute of Pharmacy, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Nadeen Salaymeh
- Department of Microbiology and Molecular Genetics, The Kuvin Centre for the Study of Infectious and Tropical Diseases, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Nicholas H Hunt
- Discipline of Pathology, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, NSW, Australia
| | - Karsten Mäder
- Institute of Pharmacy, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Jacob Golenser
- Department of Microbiology and Molecular Genetics, The Kuvin Centre for the Study of Infectious and Tropical Diseases, The Hebrew University of Jerusalem, Jerusalem, Israel
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9
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In vitro analyses of Artemisia extracts on Plasmodium falciparum suggest a complex antimalarial effect. PLoS One 2021; 16:e0240874. [PMID: 33651845 PMCID: PMC7924776 DOI: 10.1371/journal.pone.0240874] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 01/20/2021] [Indexed: 11/19/2022] Open
Abstract
Dried-leaf Artemisia annua L. (DLA) antimalarial therapy was shown effective in prior animal and human studies, but little is known about its mechanism of action. Here IC50s and ring-stage assays (RSAs) were used to compare extracts of A. annua (DLAe) to artemisinin (ART) and its derivatives in their ability to inhibit and kill Plasmodium falciparum strains 3D7, MRA1252, MRA1240, Cam3.11 and Cam3.11rev in vitro. Strains were sorbitol and Percoll synchronized to enrich for ring-stage parasites that were treated with hot water, methanol and dichloromethane extracts of DLA, artemisinin, CoArtem™, and dihydroartemisinin. Extracts of A. afra SEN were also tested. There was a correlation between ART concentration and inhibition of parasite growth. Although at 6 hr drug incubation, the RSAs for Cam3.11rev showed DLA and ART were less effective than high dose CoArtem™, 8 and 24 hr incubations yielded equivalent antiparasitic results. For Cam3.11, drug incubation time had no effect. DLAe was more effective on resistant MRA-1240 than on the sensitive MRA-1252 strain. Because results were not as robust as observed in animal and human studies, a host interaction was suspected, so sera collected from adult and pediatric Kenyan malaria patients was used in RSA inhibition experiments and compared to sera from adults naïve to the disease. The sera from both age groups of malaria patients inhibited parasite growth ≥ 70% after treatment with DLAe and compared to malaria naïve subjects suggesting some host interaction with DLA. The discrepancy between these data and in-vivo reports suggested that DLA’s effects require an interaction with the host to unlock their potential as an antimalarial therapy. Although we showed there are serum-based host effects that can kill up to 95% of parasites in vitro, it remains unclear how or if they play a role in vivo. These results further our understanding of how DLAe works against the malaria parasite in vitro.
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Giannangelo C, Siddiqui G, De Paoli A, Anderson BM, Edgington-Mitchell LE, Charman SA, Creek DJ. System-wide biochemical analysis reveals ozonide antimalarials initially act by disrupting Plasmodium falciparum haemoglobin digestion. PLoS Pathog 2020; 16:e1008485. [PMID: 32589689 PMCID: PMC7347234 DOI: 10.1371/journal.ppat.1008485] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 07/09/2020] [Accepted: 05/13/2020] [Indexed: 01/23/2023] Open
Abstract
Ozonide antimalarials, OZ277 (arterolane) and OZ439 (artefenomel), are synthetic peroxide-based antimalarials with potent activity against the deadliest malaria parasite, Plasmodium falciparum. Here we used a "multi-omics" workflow, in combination with activity-based protein profiling (ABPP), to demonstrate that peroxide antimalarials initially target the haemoglobin (Hb) digestion pathway to kill malaria parasites. Time-dependent metabolomic profiling of ozonide-treated P. falciparum infected red blood cells revealed a rapid depletion of short Hb-derived peptides followed by subsequent alterations in lipid and nucleotide metabolism, while untargeted peptidomics showed accumulation of longer Hb-derived peptides. Quantitative proteomics and ABPP assays demonstrated that Hb-digesting proteases were increased in abundance and activity following treatment, respectively. Ozonide-induced depletion of short Hb-derived peptides was less extensive in a drug-treated K13-mutant artemisinin resistant parasite line (Cam3.IIR539T) than in the drug-treated isogenic sensitive strain (Cam3.IIrev), further confirming the association between ozonide activity and Hb catabolism. To demonstrate that compromised Hb catabolism may be a primary mechanism involved in ozonide antimalarial activity, we showed that parasites forced to rely solely on Hb digestion for amino acids became hypersensitive to short ozonide exposures. Quantitative proteomics analysis also revealed parasite proteins involved in translation and the ubiquitin-proteasome system were enriched following drug treatment, suggestive of the parasite engaging a stress response to mitigate ozonide-induced damage. Taken together, these data point to a mechanism of action involving initial impairment of Hb catabolism, and indicate that the parasite regulates protein turnover to manage ozonide-induced damage.
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Affiliation(s)
- Carlo Giannangelo
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Ghizal Siddiqui
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Amanda De Paoli
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Bethany M. Anderson
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Laura E. Edgington-Mitchell
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
- Department of Maxillofacial Surgery, College of Dentistry, New York University, New York, New York, United States of America
| | - Susan A. Charman
- Centre for Drug Candidate Optimisation, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Darren J. Creek
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
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11
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Hassett MR, Roepe PD. Origin and Spread of Evolving Artemisinin-Resistant Plasmodium falciparum Malarial Parasites in Southeast Asia. Am J Trop Med Hyg 2020; 101:1204-1211. [PMID: 31642425 DOI: 10.4269/ajtmh.19-0379] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In this review, we provide an epidemiological history of the emergence and ongoing spread of evolving Plasmodium falciparum artemisinin resistance (ARTR). Southeast Asia has been the focal point for emergence and spread of multiple antimalarial drug resistance phenomena, and is once again for evolving ARTR, also known as the "delayed clearance phenotype" (DCP). The five countries most impacted, Cambodia, Thailand, Myanmar, Laos, and Vietnam, each have complex histories of antimalarial drug use over many decades, which have in part molded the use of various artemisinin combination therapies (ACTs) within each country. We catalog the use of ACTs, evolving loss of ACT efficacy, and the frequency of pfk13 mutations (mutations associated with ARTR) in the Greater Mekong Subregion and map the historical spread of ARTR/DCP parasites. These data should assist improved surveillance and deployment of next-generation ACTs.
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Affiliation(s)
- Matthew R Hassett
- Department of Biochemistry and Cellular and Molecular Biology, Georgetown University, Washington, District of Columbia.,Department of Chemistry, Georgetown University, Washington, District of Columbia
| | - Paul D Roepe
- Department of Chemistry, Georgetown University, Washington, District of Columbia.,Department of Biochemistry and Cellular and Molecular Biology, Georgetown University, Washington, District of Columbia
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Role of Plasmodium falciparum Kelch 13 Protein Mutations in P. falciparum Populations from Northeastern Myanmar in Mediating Artemisinin Resistance. mBio 2020; 11:mBio.01134-19. [PMID: 32098812 PMCID: PMC7042691 DOI: 10.1128/mbio.01134-19] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Artemisinin resistance has emerged in Southeast Asia, endangering the substantial progress in malaria elimination worldwide. It is associated with mutations in the PfK13 protein, but how PfK13 mediates artemisinin resistance is not completely understood. Here we used a new antibody against PfK13 to show that the PfK13 protein is expressed in all stages of the asexual intraerythrocytic cycle as well as in gametocytes and is partially localized in the endoplasmic reticulum. By introducing four PfK13 mutations into the 3D7 strain and reverting these mutations in field parasite isolates, we determined the impacts of these mutations identified in the parasite populations from northern Myanmar on the ring stage using the in vitro ring survival assay. The introduction of the N458Y mutation into the 3D7 background significantly increased the survival rates of the ring-stage parasites but at the cost of the reduced fitness of the parasites. Introduction of the F446I mutation, the most prevalent PfK13 mutation in northern Myanmar, did not result in a significant increase in ring-stage survival after exposure to dihydroartemisinin (DHA), but these parasites showed extended ring-stage development. Further, parasites with the F446I mutation showed only a marginal loss of fitness, partially explaining its high frequency in northern Myanmar. Conversely, reverting all these mutations, except for the C469Y mutation, back to their respective wild types reduced the ring-stage survival of these isolates in response to in vitro DHA treatment. Mutations in the Plasmodium falciparum Kelch 13 (PfK13) protein are associated with artemisinin resistance. PfK13 is essential for asexual erythrocytic development, but its function is not known. We tagged the PfK13 protein with green fluorescent protein in P. falciparum to study its expression and localization in asexual and sexual stages. We used a new antibody against PfK13 to show that the PfK13 protein is expressed ubiquitously in both asexual erythrocytic stages and gametocytes and is localized in punctate structures, partially overlapping an endoplasmic reticulum marker. We introduced into the 3D7 strain four PfK13 mutations (F446I, N458Y, C469Y, and F495L) identified in parasites from the China-Myanmar border area and characterized the in vitro artemisinin response phenotypes of the mutants. We found that all the parasites with the introduced PfK13 mutations showed higher survival rates in the ring-stage survival assay (RSA) than the wild-type (WT) control, but only parasites with N458Y displayed a significantly higher RSA value (26.3%) than the WT control. After these PfK13 mutations were reverted back to the WT in field parasite isolates, all revertant parasites except those with the C469Y mutation showed significantly lower RSA values than their respective parental isolates. Although the 3D7 parasites with introduced F446I, the predominant PfK13 mutation in northern Myanmar, did not show significantly higher RSA values than the WT, they had prolonged ring-stage development and showed very little fitness cost in in vitro culture competition assays. In comparison, parasites with the N458Y mutations also had a prolonged ring stage and showed upregulated resistance pathways in response to artemisinin, but this mutation produced a significant fitness cost, potentially leading to their lower prevalence in the Greater Mekong subregion.
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Wong HN, Padín-Irizarry V, van der Watt ME, Reader J, Liebenberg W, Wiesner L, Smith P, Eribez K, Winzeler EA, Kyle DE, Birkholtz LM, Coertzen D, Haynes RK. Optimal 10-Aminoartemisinins With Potent Transmission-Blocking Capabilities for New Artemisinin Combination Therapies-Activities Against Blood Stage P. falciparum Including PfKI3 C580Y Mutants and Liver Stage P. berghei Parasites. Front Chem 2020; 7:901. [PMID: 31998692 PMCID: PMC6967409 DOI: 10.3389/fchem.2019.00901] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Accepted: 12/13/2019] [Indexed: 12/31/2022] Open
Abstract
We have demonstrated previously that amino-artemisinins including artemiside and artemisone in which an amino group replaces the oxygen-bearing substituents attached to C-10 of the current clinical artemisinin derivatives dihydroartemisinin (DHA), artemether and artesunate, display potent activities in vitro against the asexual blood stages of Plasmodium falciparum (Pf). In particular, the compounds are active against late blood stage Pf gametocytes, and are strongly synergistic in combination with the redox active drug methylene blue. In order to fortify the eventual selection of optimum amino-artemisinins for development into new triple combination therapies also active against artemisinin-resistant Pf mutants, we have prepared new amino-artemisinins based on the easily accessible and inexpensive DHA-piperazine. The latter was converted into alkyl- and aryl sulfonamides, ureas and amides. These derivatives were screened together with the comparator drugs DHA and the hitherto most active amino-artemisinins artemiside and artemisone against asexual and sexual blood stages of Pf and liver stage P. berghei (Pb) sporozoites. Several of the new amino-artemisinins bearing aryl-urea and -amide groups are potently active against both asexual, and late blood stage gametocytes (IC50 0.4-1.0 nM). Although the activities are superior to those of artemiside (IC50 1.5 nM) and artemisone (IC50 42.4 nM), the latter are more active against the liver stage Pb sporozoites (IC50 artemisone 28 nM). In addition, early results indicate these compounds tend not to display reduced susceptibility against parasites bearing the Pf Kelch 13 propeller domain C580Y mutation characteristic of artemisinin-resistant Pf. Thus, the advent of the amino-artemisinins including artemiside and artemisone will enable the development of new combination therapies that by virtue of the amino-artemisinin component itself will possess intrinsic transmission-blocking capabilities and may be effective against artemisinin resistant falciparum malaria.
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Affiliation(s)
- Ho Ning Wong
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences, North-West University, Potchefstroom, South Africa
| | - Vivian Padín-Irizarry
- Center for Tropical & Emerging Global Diseases, Coverdell Center, University of Georgia, Athens, GA, United States
| | - Mariëtte E van der Watt
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa
| | - Janette Reader
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa
| | - Wilna Liebenberg
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences, North-West University, Potchefstroom, South Africa
| | - Lubbe Wiesner
- Division of Clinical Pharmacology, Department of Medicine, Groote Schuur Hospital, University of Cape Town, Cape Town, South Africa
| | - Peter Smith
- Division of Clinical Pharmacology, Department of Medicine, Groote Schuur Hospital, University of Cape Town, Cape Town, South Africa
| | - Korina Eribez
- School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Elizabeth A Winzeler
- School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Dennis E Kyle
- Center for Tropical & Emerging Global Diseases, Coverdell Center, University of Georgia, Athens, GA, United States
| | - Lyn-Marie Birkholtz
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa
| | - Dina Coertzen
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa
| | - Richard K Haynes
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences, North-West University, Potchefstroom, South Africa
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14
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Stokes BH, Yoo E, Murithi JM, Luth MR, Afanasyev P, da Fonseca PCA, Winzeler EA, Ng CL, Bogyo M, Fidock DA. Covalent Plasmodium falciparum-selective proteasome inhibitors exhibit a low propensity for generating resistance in vitro and synergize with multiple antimalarial agents. PLoS Pathog 2019; 15:e1007722. [PMID: 31170268 PMCID: PMC6553790 DOI: 10.1371/journal.ppat.1007722] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 03/21/2019] [Indexed: 01/12/2023] Open
Abstract
Therapeutics with novel modes of action and a low risk of generating resistance are urgently needed to combat drug-resistant Plasmodium falciparum malaria. Here, we report that the peptide vinyl sulfones WLL-vs (WLL) and WLW-vs (WLW), highly selective covalent inhibitors of the P. falciparum proteasome, potently eliminate genetically diverse parasites, including K13-mutant, artemisinin-resistant lines, and are particularly active against ring-stage parasites. Selection studies reveal that parasites do not readily acquire resistance to WLL or WLW and that mutations in the β2, β5 or β6 subunits of the 20S proteasome core particle or in components of the 19S proteasome regulatory particle yield only <five-fold decreases in parasite susceptibility. This result compares favorably against previously published non-covalent inhibitors of the Plasmodium proteasome that can select for resistant parasites with >hundred-fold decreases in susceptibility. We observed no cross-resistance between WLL and WLW. Moreover, most mutations that conferred a modest loss of parasite susceptibility to one inhibitor significantly increased sensitivity to the other. These inhibitors potently synergized multiple chemically diverse classes of antimalarial agents, implicating a shared disruption of proteostasis in their modes of action. These results underscore the potential of targeting the Plasmodium proteasome with covalent small molecule inhibitors as a means of combating multidrug-resistant malaria. The spread of artemisinin-resistant Plasmodium falciparum malaria across Southeast Asia creates an imperative to develop new treatment options with compounds that are not susceptible to existing mechanisms of antimalarial drug resistance. Recent work has identified the P. falciparum proteasome as a promising drug target. Here, we report potent antimalarial activity of highly selective vinyl sulfone-conjugated peptide proteasome inhibitors, including against artemisinin-resistant P. falciparum early ring-stage parasites that are traditionally difficult to treat. Unlike many advanced antimalarial candidates, these covalent proteasome inhibitors do not readily select for resistance. Selection studies with cultured parasites reveal infrequent and minor decreases in susceptibility resulting from point mutations in components of the 26S proteasome, which we model using cryo-electron microscopy-based structural data. No parasites were observed to be cross-resistant to both compounds; in fact, partial resistance to one compound often created hypersensitivity to the other. We also document potent synergy between these covalent proteasome inhibitors and multiple classes of antimalarial agents, including dihydroartemisinin, the clinical candidate OZ439, and the parasite transmission-blocking agent methylene blue. Proteasome inhibitors have significant promise as components of novel combination therapies to treat multidrug-resistant malaria.
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Affiliation(s)
- Barbara H. Stokes
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, United States of America
| | - Euna Yoo
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, United States of America
| | - James M. Murithi
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, United States of America
| | - Madeline R. Luth
- Division of Host-Microbe Systems & Therapeutics, Department of Pediatrics, University of California San Diego, School of Medicine, San Diego, CA, United States of America
| | - Pavel Afanasyev
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Paula C. A. da Fonseca
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Elizabeth A. Winzeler
- Division of Host-Microbe Systems & Therapeutics, Department of Pediatrics, University of California San Diego, School of Medicine, San Diego, CA, United States of America
| | - Caroline L. Ng
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, United States of America
- * E-mail: (CLN); (MB); (DAF)
| | - Matthew Bogyo
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, United States of America
- * E-mail: (CLN); (MB); (DAF)
| | - David A. Fidock
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, United States of America
- Division of Infectious Diseases, Department of Medicine, Columbia University Irving Medical Center, New York, NY, United States of America
- * E-mail: (CLN); (MB); (DAF)
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15
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Ozonide Antimalarial Activity in the Context of Artemisinin-Resistant Malaria. Trends Parasitol 2019; 35:529-543. [PMID: 31176584 DOI: 10.1016/j.pt.2019.05.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 04/02/2019] [Accepted: 05/01/2019] [Indexed: 12/18/2022]
Abstract
The ozonides are one of the most advanced drug classes in the antimalarial development pipeline and were designed to improve on limitations associated with current front-line artemisinin-based therapies. Like the artemisinins, the pharmacophoric peroxide bond of ozonides is essential for activity, and it appears that these antimalarials share a similar mode of action, raising the possibility of cross-resistance. Resistance to artemisinins is associated with Plasmodium falciparum mutations that allow resistant parasites to escape short-term artemisinin-mediated damage (elimination half-life ~1 h). Importantly, some ozonides (e.g., OZ439) have a sustained in vivo drug exposure profile, providing a major pharmacokinetic advantage over the artemisinin derivatives. Here, we describe recent progress made towards understanding ozonide antimalarial activity and discuss ozonide utility within the context of artemisinin resistance.
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16
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Heller LE, Roepe PD. Artemisinin-Based Antimalarial Drug Therapy: Molecular Pharmacology and Evolving Resistance. Trop Med Infect Dis 2019; 4:tropicalmed4020089. [PMID: 31167396 PMCID: PMC6631165 DOI: 10.3390/tropicalmed4020089] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 05/21/2019] [Accepted: 05/24/2019] [Indexed: 12/27/2022] Open
Abstract
The molecular pharmacology of artemisinin (ART)-based antimalarial drugs is incompletely understood. Clinically, these drugs are used in combination with longer lasting partner drugs in several different artemisinin combination therapies (ACTs). ACTs are currently the standard of care against Plasmodium falciparum malaria across much of the world. A harbinger of emerging artemisinin resistance (ARTR), known as the delayed clearance phenotype (DCP), has been well documented in South East Asia (SEA) and is beginning to affect the efficacy of some ACTs. Though several genetic mutations have been associated with ARTR/DCP, a molecular mechanism remains elusive. This paper summarizes our current understanding of ART molecular pharmacology and hypotheses for ARTR/DCP.
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Affiliation(s)
- Laura E Heller
- Departments of Chemistry and of Biochemistry and Cellular and Molecular Biology, Georgetown University, 37th and O Streets NW, Washington, DC 20057, USA.
| | - Paul D Roepe
- Departments of Chemistry and of Biochemistry and Cellular and Molecular Biology, Georgetown University, 37th and O Streets NW, Washington, DC 20057, USA.
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17
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Rout S, Mahapatra RK. Plasmodium falciparum: Multidrug resistance. Chem Biol Drug Des 2019; 93:737-759. [DOI: 10.1111/cbdd.13484] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 01/05/2019] [Accepted: 01/09/2019] [Indexed: 12/25/2022]
Affiliation(s)
- Subhashree Rout
- School of BiotechnologyKIIT University Bhubaneswar Odisha India
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18
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Heller LE, Goggins E, Roepe PD. Dihydroartemisinin-Ferriprotoporphyrin IX Adduct Abundance in Plasmodium falciparum Malarial Parasites and the Relationship to Emerging Artemisinin Resistance. Biochemistry 2018; 57:6935-6945. [PMID: 30512926 DOI: 10.1021/acs.biochem.8b00960] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Previously (Heller, L. E., and Roepe, P. D. Quantification of Free Ferriprotoporphyrin IX Heme and Hemozoin for Artemisinin Sensitive versus Delayed Clearance Phenotype Plasmodium falciparum Malarial Parasites. Biochemistry, DOI: 10.1021/acs.biochem.8b00959, preceding paper in this issue), we quantified free ferriprotoporphyrin IX (FPIX) heme abundance for control versus delayed clearance phenotype (DCP) intraerythrocytic Plasmodium falciparum malarial parasites. Because artemisinin drugs are activated by free FPIX, these data predict that the abundance of long-hypothesized toxic artemisinin drug-FPIX covalent adducts might differ for control versus DCP parasites. If so, this would have important repercussions for understanding the mechanism of the DCP, also known as emerging artemisinin resistance. To test these predictions, we studied in vitro formation of FPIX-dihydroartemisinin (DHA) adducts and then for the first time quantified the abundance of FPIX-DHA adducts formed within live P. falciparum versus the stage of intraerythrocytic development. Using matched isogenic parasite strains, we quantified the adduct for DCP versus control parasite strains and found that mutant PfK13 mediates lower adduct abundance for DCP parasites. The results suggest improved models for the molecular pharmacology of artemisinin-based antimalarial drugs and the molecular mechanism of the DCP.
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Affiliation(s)
- Laura E Heller
- Department of Chemistry and Department of Biochemistry and Cellular and Molecular Biology , Georgetown University , 37th and O Streets Northwest , Washington, D.C. 20057 , United States
| | - Eibhlin Goggins
- Department of Chemistry and Department of Biochemistry and Cellular and Molecular Biology , Georgetown University , 37th and O Streets Northwest , Washington, D.C. 20057 , United States
| | - Paul D Roepe
- Department of Chemistry and Department of Biochemistry and Cellular and Molecular Biology , Georgetown University , 37th and O Streets Northwest , Washington, D.C. 20057 , United States
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19
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Pasupureddy R, Atul, Seshadri S, Pande V, Dixit R, Pandey KC. Current scenario and future strategies to fight artemisinin resistance. Parasitol Res 2018; 118:29-42. [PMID: 30478733 DOI: 10.1007/s00436-018-6126-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 10/19/2018] [Indexed: 02/05/2023]
Abstract
Despite several setbacks in the fight against malaria such as insecticide and drug resistance as well as low efficacy of available vaccines, considerable success in reducing malaria burden has been achieved in the past decade. Artemisinins (ARTs and their combination therapies, ACTs), the current frontline drugs against uncomplicated malaria, rapidly kill plasmodial parasites and are non-toxic at short exposures. Though the exact mode of action remains unclear, the endoperoxide bridge, indispensable for ART activity, is thought to react with heme released from hemoglobin hydrolysis and generate free radicals that alkylate multiple protein targets, thereby disrupting proteostasis pathways. However, rapid development of ART resistance in recent years with no potential alternatives on the horizon threaten the elimination efforts. The Greater Mekong Subregion in South-East Asia continues to churn out mutants resistant to multiple ACTs and detected in increasingly expanding geographies. Extensive research on ART-resistant strains have identified a potential candidate Kelch13, crucial for mediating ART resistance. Parasites with mutations in the propeller domains of Plasmodium falciparum Kelch13 protein were shown to have enhanced phosphatidylinositol 3-kinase levels that were concomitant with delayed parasite clearance. Current research focused on understanding the mechanism of Kelch13-mediated ART resistance could provide better insights into Plasmodium resistome. This review covers the current proposed mechanisms of ART activity, resistance strategies adopted by the parasite in response to ACTs and possible future approaches to mitigate the spread of resistance from South-East Asia.
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Affiliation(s)
- Rahul Pasupureddy
- National Institute of Malaria Research, Dwarka Sector 8, New Delhi, 110077, India.,Institute of Science, Nirma University, SG Highway, Ahmedabad, Gujarat, 382481, India
| | - Atul
- National Institute of Malaria Research, Dwarka Sector 8, New Delhi, 110077, India.,Department of Biotechnology, Kumaun University, Nainital, Uttarakhand, 263001, India
| | - Sriram Seshadri
- Institute of Science, Nirma University, SG Highway, Ahmedabad, Gujarat, 382481, India
| | - Veena Pande
- Department of Biotechnology, Kumaun University, Nainital, Uttarakhand, 263001, India
| | - Rajnikant Dixit
- National Institute of Malaria Research, Dwarka Sector 8, New Delhi, 110077, India
| | - Kailash C Pandey
- National Institute of Malaria Research, Dwarka Sector 8, New Delhi, 110077, India. .,Department of Biochemistry, Indian Council of Medical Research, National Institute for Research in Environmental Health, Bhopal, Madhya Pradesh, 462001, India.
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20
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Mathews ES, Odom John AR. Tackling resistance: emerging antimalarials and new parasite targets in the era of elimination. F1000Res 2018; 7. [PMID: 30135714 PMCID: PMC6073090 DOI: 10.12688/f1000research.14874.1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/26/2018] [Indexed: 12/27/2022] Open
Abstract
Malaria remains a significant contributor to global human mortality, and roughly half the world’s population is at risk for infection with
Plasmodium spp. parasites. Aggressive control measures have reduced the global prevalence of malaria significantly over the past decade. However, resistance to available antimalarials continues to spread, including resistance to the widely used artemisinin-based combination therapies. Novel antimalarial compounds and therapeutic targets are greatly needed. This review will briefly discuss several promising current antimalarial development projects, including artefenomel, ferroquine, cipargamin, SJ733, KAF156, MMV048, and tafenoquine. In addition, we describe recent large-scale genetic and resistance screens that have been instrumental in target discovery. Finally, we highlight new antimalarial targets, which include essential transporters and proteases. These emerging antimalarial compounds and therapeutic targets have the potential to overcome multi-drug resistance in ongoing efforts toward malaria elimination.
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Affiliation(s)
- Emily S Mathews
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Audrey R Odom John
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri, USA.,Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
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21
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Lobo L, Cabral LIL, Sena MI, Guerreiro B, Rodrigues AS, de Andrade-Neto VF, Cristiano MLS, Nogueira F. New endoperoxides highly active in vivo and in vitro against artemisinin-resistant Plasmodium falciparum. Malar J 2018; 17:145. [PMID: 29615130 PMCID: PMC5883364 DOI: 10.1186/s12936-018-2281-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 03/21/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The emergence and spread of Plasmodium falciparum resistance to artemisinin-based combination therapy in Southeast Asia prompted the need to develop new endoperoxide-type drugs. METHODS A chemically diverse library of endoperoxides was designed and synthesized. The compounds were screened for in vitro and in vivo anti-malarial activity using, respectively, the SYBR Green I assay and a mouse model. Ring survival and mature stage survival assays were performed against artemisinin-resistant and artemisinin-sensitive P. falciparum strains. Cytotoxicity was evaluated against mammalian cell lines V79 and HepG2, using the MTT assay. RESULTS The synthesis and anti-malarial activity of 21 new endoperoxide-derived compounds is reported, where the peroxide pharmacophore is part of a trioxolane (ozonide) or a tetraoxane moiety, flanked by adamantane and a substituted cyclohexyl ring. Eight compounds exhibited sub-micromolar anti-malarial activity (IC50 0.3-71.1 nM), no cross-resistance with artemisinin or quinolone derivatives and negligible cytotoxicity towards mammalian cells. From these, six produced ring stage survival < 1% against the resistant strain IPC5202 and three of them totally suppressed Plasmodium berghei parasitaemia in mice after oral administration. CONCLUSION The investigated, trioxolane-tetrazole conjugates LC131 and LC136 emerged as potential anti-malarial candidates; they show negligible toxicity towards mammalian cells, ability to kill intra-erythrocytic asexual stages of artemisinin-resistant P. falciparum and capacity to totally suppress P. berghei parasitaemia in mice.
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Affiliation(s)
- Lis Lobo
- Global Health and Tropical Medicine, GHTM, Unidade de Ensino e Investigação de Parasitologia Médica, Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa, UNL, Rua da Junqueira no 100, 1349-008, Lisbon, Portugal.,Laboratório de Biologia da Malária e Toxoplasmose, Departamento de Microbiologia e Parasitologia, Universidade Federal do Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
| | - Lília I L Cabral
- Centre of Marine Sciences, CCMAR, Universidade do Algarve, UAlg, Campus de Gambelas, 8005-139, Faro, Portugal.,Departmento de Química e Farmácia, Faculdade de Ciências e Tecnologia, FCT, Universidade do Algarve, Faro, Portugal
| | - Maria Inês Sena
- Centre of Marine Sciences, CCMAR, Universidade do Algarve, UAlg, Campus de Gambelas, 8005-139, Faro, Portugal
| | - Bruno Guerreiro
- Centre of Marine Sciences, CCMAR, Universidade do Algarve, UAlg, Campus de Gambelas, 8005-139, Faro, Portugal.,Departmento de Química e Farmácia, Faculdade de Ciências e Tecnologia, FCT, Universidade do Algarve, Faro, Portugal
| | - António Sebastião Rodrigues
- Centre for Toxicogenomics and Human Health, Genetics, Oncology and Human Toxicology, Nova Medical School, Lisbon, Portugal
| | - Valter Ferreira de Andrade-Neto
- Laboratório de Biologia da Malária e Toxoplasmose, Departamento de Microbiologia e Parasitologia, Universidade Federal do Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
| | - Maria L S Cristiano
- Centre of Marine Sciences, CCMAR, Universidade do Algarve, UAlg, Campus de Gambelas, 8005-139, Faro, Portugal. .,Departmento de Química e Farmácia, Faculdade de Ciências e Tecnologia, FCT, Universidade do Algarve, Faro, Portugal.
| | - Fatima Nogueira
- Global Health and Tropical Medicine, GHTM, Unidade de Ensino e Investigação de Parasitologia Médica, Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa, UNL, Rua da Junqueira no 100, 1349-008, Lisbon, Portugal.
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22
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Blasco B, Leroy D, Fidock DA. Antimalarial drug resistance: linking Plasmodium falciparum parasite biology to the clinic. Nat Med 2017; 23:917-928. [PMID: 28777791 DOI: 10.1038/nm.4381] [Citation(s) in RCA: 325] [Impact Index Per Article: 46.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Accepted: 06/30/2017] [Indexed: 02/08/2023]
Abstract
The global adoption of artemisinin-based combination therapies (ACTs) in the early 2000s heralded a new era in effectively treating drug-resistant Plasmodium falciparum malaria. However, several Southeast Asian countries have now reported the emergence of parasites that have decreased susceptibility to artemisinin (ART) derivatives and ACT partner drugs, resulting in increasing rates of treatment failures. Here we review recent advances in understanding how antimalarials act and how resistance develops, and discuss new strategies for effectively combatting resistance, optimizing treatment and advancing the global campaign to eliminate malaria.
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Affiliation(s)
| | - Didier Leroy
- Medicines for Malaria Venture, Geneva, Switzerland
| | - David A Fidock
- Department of Microbiology and Immunology, Columbia University Medical Center, New York, New York, USA.,Division of Infectious Diseases, Department of Medicine, Columbia University Medical Center, New York, New York, USA
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23
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Hassett MR, Sternberg AR, Riegel BE, Thomas CJ, Roepe PD. Heterologous Expression, Purification, and Functional Analysis of Plasmodium falciparum Phosphatidylinositol 3′-Kinase. Biochemistry 2017; 56:4335-4345. [DOI: 10.1021/acs.biochem.7b00416] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Matthew R. Hassett
- Department of Chemistry and Department of Biochemistry & Cellular & Molecular Biology, Georgetown University, 37th and O Streets NW, Washington, D.C. 20057, United States
| | - Anna R. Sternberg
- Department of Chemistry and Department of Biochemistry & Cellular & Molecular Biology, Georgetown University, 37th and O Streets NW, Washington, D.C. 20057, United States
| | - Bryce E. Riegel
- Department of Chemistry and Department of Biochemistry & Cellular & Molecular Biology, Georgetown University, 37th and O Streets NW, Washington, D.C. 20057, United States
| | - Craig J. Thomas
- Division
of Preclinical Innovation, National Center for Advancing Translational
Sciences, National Institutes of Health, Rockville, Maryland 20892, United States
| | - Paul D. Roepe
- Department of Chemistry and Department of Biochemistry & Cellular & Molecular Biology, Georgetown University, 37th and O Streets NW, Washington, D.C. 20057, United States
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24
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Plasmodium falciparum K13 Mutations Differentially Impact Ozonide Susceptibility and Parasite Fitness In Vitro. mBio 2017; 8:mBio.00172-17. [PMID: 28400526 PMCID: PMC5388803 DOI: 10.1128/mbio.00172-17] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The emergence and spread in Southeast Asia of Plasmodium falciparum resistance to artemisinin (ART) derivatives, the cornerstone of first-line artemisinin-based combination therapies (ACTs), underscore the urgent need to identify suitable replacement drugs. Discovery and development efforts have identified a series of ozonides with attractive chemical and pharmacological properties that are being touted as suitable replacements. Partial resistance to ART, defined as delayed parasite clearance in malaria patients treated with an ART derivative or an ACT, has been associated with mutations in the P. falciparum K13 gene. In light of reports showing that ART derivatives and ozonides share similar modes of action, we have investigated whether parasites expressing mutant K13 are cross-resistant to the ozonides OZ439 (artefenomel) and OZ227 (arterolane). This work used a panel of culture-adapted clinical isolates from Cambodia that were genetically edited to express variant forms of K13. Phenotypic analyses employed ring-stage survival assays (ring-stage survival assay from 0 to 3 h [RSA0–3h]), whose results have earlier been shown to correlate with parasite clearance rates in patients. Our results document cross-resistance between OZ277 and dihydroartemisinin (DHA), a semisynthetic derivative of ART, in parasites carrying the K13 mutations C580Y, R539T, and I543T. For OZ439, we observed cross-resistance only for parasites that carried the rare K13 I543T mutation, with no evidence of cross-resistance afforded by the prevalent C580Y mutation. Mixed-culture competition experiments with isogenic lines carrying modified K13 revealed variable growth deficits depending on the K13 mutation and parasite strain and provide a rationale for the broad dissemination of the fitness-neutral K13 C580Y mutation throughout strains currently circulating in Southeast Asia. ACTs have helped halve the malaria disease burden in recent years; however, emerging resistance to ART derivatives threatens to reverse this substantial progress. Resistance is driven primarily by mutations in the P. falciparum K13 gene. These mutations pose a threat to ozonides, touted as promising alternatives to ARTs that share a similar mode of action. We report that DHA was considerably more potent than OZ439 and OZ277 against ART-sensitive asexual blood-stage parasites cultured in vitro. We also document that mutant K13 significantly compromised the activity of the registered drug OZ277. In contrast, OZ439 remained effective against most parasite lines expressing mutant K13, with the exception of I543T that merits further monitoring in field-based OZ439 efficacy studies. K13 mutations differed considerably in their impact on parasite growth rates, in a strain-dependent context, with the most prevalent C580Y mutation being fitness neutral in recently culture-adapted strains from Cambodia, the epicenter of emerging ART resistance.
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25
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Baumgärtner F, Jourdan J, Scheurer C, Blasco B, Campo B, Mäser P, Wittlin S. In vitro activity of anti-malarial ozonides against an artemisinin-resistant isolate. Malar J 2017; 16:45. [PMID: 28122617 PMCID: PMC5267415 DOI: 10.1186/s12936-017-1696-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Accepted: 01/13/2017] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Recently published data suggest that artemisinin derivatives and synthetic peroxides, such as the ozonides OZ277 and OZ439, have a similar mode of action. Here the cross-resistance of OZ277 and OZ439 and four additional next-generation ozonides was probed against the artemisinin-resistant clinical isolate Plasmodium falciparum Cam3.I, which carries the K13-propeller mutation R539T (Cam3.IR539T). METHODS The previously described in vitro ring-stage survival assay (RSA0-3h) was employed and a simplified variation of the original protocol was developed. RESULTS At the pharmacologically relevant concentration of 700 nM, all six ozonides were highly effective against the dihydroartemisinin-resistant P. falciparum Cam3.IR539T parasites, showing a per cent survival ranging from <0.01 to 1.83%. A simplified version of the original RSA0-3h method was developed and gave similar results, thus providing a practical drug discovery tool for further optimization of next-generation anti-malarial peroxides. CONCLUSION The absence of in vitro cross-resistance against the artemisinin-resistant clinical isolate Cam3.IR539T suggests that ozonides could be effective against artemisinin-resistant P. falciparum. How this will translate to the human situation in clinical settings remains to be investigated.
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Affiliation(s)
- Fabian Baumgärtner
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002 Basel, Switzerland
- University of Basel, Petersplatz 1, 4001 Basel, Switzerland
| | - Joëlle Jourdan
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002 Basel, Switzerland
- University of Basel, Petersplatz 1, 4001 Basel, Switzerland
| | - Christian Scheurer
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002 Basel, Switzerland
- University of Basel, Petersplatz 1, 4001 Basel, Switzerland
| | - Benjamin Blasco
- Medicines for Malaria Venture, ICC, 20 Route de Pré-Bois, PO Box 1826, 1215 Geneva, Switzerland
| | - Brice Campo
- Medicines for Malaria Venture, ICC, 20 Route de Pré-Bois, PO Box 1826, 1215 Geneva, Switzerland
| | - Pascal Mäser
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002 Basel, Switzerland
- University of Basel, Petersplatz 1, 4001 Basel, Switzerland
| | - Sergio Wittlin
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002 Basel, Switzerland
- University of Basel, Petersplatz 1, 4001 Basel, Switzerland
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