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Bhatnagar S, Nicklas S, Morrisey JM, Goldberg DE, Vaidya AB. Diverse Chemical Compounds Target Plasmodium falciparum Plasma Membrane Lipid Homeostasis. ACS Infect Dis 2019; 5:550-558. [PMID: 30638365 DOI: 10.1021/acsinfecdis.8b00277] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Lipid homeostasis is essential to the maintenance of life. We previously reported that disruptions of the parasite Na+ homeostasis via inhibition of PfATP4 resulted in elevated cholesterol within the parasite plasma membrane as assessed by saponin sensitivity. A large number of compounds have been shown to target the parasite Na+ homeostasis. We screened 800 compounds from the Malaria and Pathogen Boxes to identify chemotypes that disrupted the parasite plasma membrane lipid homeostasis. Here, we show that the compounds disrupting parasite Na+ homeostasis also induced saponin sensitivity, an indication of parasite lipid homeostasis disruption. Remarkably, 13 compounds were identified that altered the plasma membrane lipid composition independently of the Na+ homeostasis disruption. Further studies suggest that these compounds target the Plasmodium falciparum Niemann-Pick type C1-related (PfNCR1) protein, which is hypothesized to be involved in maintaining plasma membrane lipid composition. PfNCR1, like PfATP4, appears to be targeted by multiple chemotypes with the potential for drug discovery.
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Affiliation(s)
- Suyash Bhatnagar
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, Pennsylvania 19129, United States of America
| | - Sezin Nicklas
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, Pennsylvania 19129, United States of America
| | - Joanne M. Morrisey
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, Pennsylvania 19129, United States of America
| | - Daniel E. Goldberg
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, 4990 Children’s Place, St. Louis, Missouri 63110, United States of America
| | - Akhil B. Vaidya
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, Pennsylvania 19129, United States of America
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52
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Tse EG, Korsik M, Todd MH. The past, present and future of anti-malarial medicines. Malar J 2019; 18:93. [PMID: 30902052 PMCID: PMC6431062 DOI: 10.1186/s12936-019-2724-z] [Citation(s) in RCA: 208] [Impact Index Per Article: 41.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 03/12/2019] [Indexed: 11/10/2022] Open
Abstract
Great progress has been made in recent years to reduce the high level of suffering caused by malaria worldwide. Notably, the use of insecticide-treated mosquito nets for malaria prevention and the use of artemisinin-based combination therapy (ACT) for malaria treatment have made a significant impact. Nevertheless, the development of resistance to the past and present anti-malarial drugs highlights the need for continued research to stay one step ahead. New drugs are needed, particularly those with new mechanisms of action. Here the range of anti-malarial medicines developed over the years are reviewed, beginning with the discovery of quinine in the early 1800s, through to modern day ACT and the recently-approved tafenoquine. A number of new potential anti-malarial drugs currently in development are outlined, along with a description of the hit to lead campaign from which it originated. Finally, promising novel mechanisms of action for these and future anti-malarial medicines are outlined.
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Affiliation(s)
- Edwin G Tse
- School of Chemistry, The University of Sydney, Sydney, NSW, 2006, Australia.
| | - Marat Korsik
- School of Chemistry, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Matthew H Todd
- School of Chemistry, The University of Sydney, Sydney, NSW, 2006, Australia. .,School of Pharmacy, University College London, London, WC1N 1AX, United Kingdom.
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53
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Istvan ES, Das S, Bhatnagar S, Beck JR, Owen E, Llinas M, Ganesan SM, Niles JC, Winzeler E, Vaidya AB, Goldberg DE. Plasmodium Niemann-Pick type C1-related protein is a druggable target required for parasite membrane homeostasis. eLife 2019; 8:40529. [PMID: 30888318 PMCID: PMC6424564 DOI: 10.7554/elife.40529] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 02/05/2019] [Indexed: 01/05/2023] Open
Abstract
Plasmodium parasites possess a protein with homology to Niemann-Pick Type C1 proteins (Niemann-Pick Type C1-Related protein, NCR1). We isolated parasites with resistance-conferring mutations in Plasmodium falciparum NCR1 (PfNCR1) during selections with three diverse small-molecule antimalarial compounds and show that the mutations are causative for compound resistance. PfNCR1 protein knockdown results in severely attenuated growth and confers hypersensitivity to the compounds. Compound treatment or protein knockdown leads to increased sensitivity of the parasite plasma membrane (PPM) to the amphipathic glycoside saponin and engenders digestive vacuoles (DVs) that are small and malformed. Immuno-electron microscopy and split-GFP experiments localize PfNCR1 to the PPM. Our experiments show that PfNCR1 activity is critically important for the composition of the PPM and is required for DV biogenesis, suggesting PfNCR1 as a novel antimalarial drug target. Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).
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Affiliation(s)
- Eva S Istvan
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, United States.,Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, United States
| | - Sudipta Das
- Department of Microbiology and Immunology, Center for Molecular Parasitology, Drexel University College of Medicine, Philadelphia, United States
| | - Suyash Bhatnagar
- Department of Microbiology and Immunology, Center for Molecular Parasitology, Drexel University College of Medicine, Philadelphia, United States
| | - Josh R Beck
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, United States.,Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, United States
| | - Edward Owen
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, United States.,Huck Center for Malaria Research, Pennsylvania State University, University Park, United States.,Department of Chemistry, Pennsylvania State University, University Park, United States
| | - Manuel Llinas
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, United States.,Huck Center for Malaria Research, Pennsylvania State University, University Park, United States.,Department of Chemistry, Pennsylvania State University, University Park, United States
| | - Suresh M Ganesan
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, United States
| | - Jacquin C Niles
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, United States
| | - Elizabeth Winzeler
- Department of Pediatrics, University of California San Diego School of Medicine, La Jolla, United States
| | - Akhil B Vaidya
- Department of Microbiology and Immunology, Center for Molecular Parasitology, Drexel University College of Medicine, Philadelphia, United States
| | - Daniel E Goldberg
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, United States.,Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, United States
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54
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Plasmodium knowlesi exhibits distinct in vitro drug susceptibility profiles from those of Plasmodium falciparum. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2019; 9:93-99. [PMID: 30831468 PMCID: PMC6403410 DOI: 10.1016/j.ijpddr.2019.02.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 02/14/2019] [Accepted: 02/18/2019] [Indexed: 12/16/2022]
Abstract
New antimalarial agents are identified and developed after extensive testing on Plasmodium falciparum parasites that can be grown in vitro. These susceptibility studies are important to inform lead optimisation and support further drug development. Until recently, little was known about the susceptibility of non-falciparum species as these had not been adapted to in vitro culture. The recent culture adaptation of P. knowlesi has therefore offered an opportunity to routinely define the drug susceptibility of this species, which is phylogenetically closer to all other human malarias than is P. falciparum. We compared the in vitro susceptibility of P. knowlesi and P. falciparum to a range of established and novel antimalarial agents under identical assay conditions. We demonstrated that P. knowlesi is significantly less susceptible than P. falciparum to six of the compounds tested; and notably these include three ATP4 inhibitors currently under development as novel antimalarial agents, and one investigational antimalarial, AN13762, which is 67 fold less effective against P. knowlesi. For the other compounds there was a less than two-fold difference in susceptibility between species. We then compared the susceptibility of a recent P. knowlesi isolate, UM01, to that of the well-established, older A1-H.1 clone. This recent isolate showed similar in vitro drug susceptibility to the A1-H.1 clone, supporting the ongoing use of the better characterised clone to further study drug susceptibility. Lastly, we used isobologram analysis to explore the interaction of a selection of drug combinations and showed similar drug interactions across species. The species differences in drug susceptibility reported by us here and previously, support adding in vitro drug screens against P. knowlesi to those using P. falciparum strains to inform new drug discovery and lead optimisation. P. knowlesi >6-fold less susceptible to several ATP4 inhibitors than P. falciparum. P. knowlesi equally susceptible to artemisinins and synthetic endoperoxides. Isobolograms show similar drug interactions for P. knowlesi and P. falciparum. New P. knowlesi isolate (UM01) similarly susceptible to antimalarials as A1-H.1
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55
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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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56
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Lehane AM, Dennis ASM, Bray KO, Li D, Rajendran E, McCoy JM, McArthur HM, Winterberg M, Rahimi F, Tonkin CJ, Kirk K, van Dooren GG. Characterization of the ATP4 ion pump in Toxoplasma gondii. J Biol Chem 2019; 294:5720-5734. [PMID: 30723156 DOI: 10.1074/jbc.ra118.006706] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 01/31/2019] [Indexed: 12/22/2022] Open
Abstract
The Plasmodium falciparum ATPase PfATP4 is the target of a diverse range of antimalarial compounds, including the clinical drug candidate cipargamin. PfATP4 was originally annotated as a Ca2+ transporter, but recent evidence suggests that it is a Na+ efflux pump, extruding Na+ in exchange for H+ Here we demonstrate that ATP4 proteins belong to a clade of P-type ATPases that are restricted to apicomplexans and their closest relatives. We employed a variety of genetic and physiological approaches to investigate the ATP4 protein of the apicomplexan Toxoplasma gondii, TgATP4. We show that TgATP4 is a plasma membrane protein. Knockdown of TgATP4 had no effect on resting pH or Ca2+ but rendered parasites unable to regulate their cytosolic Na+ concentration ([Na+]cyt). PfATP4 inhibitors caused an increase in [Na+]cyt and a cytosolic alkalinization in WT but not TgATP4 knockdown parasites. Parasites in which TgATP4 was knocked down or disrupted exhibited a growth defect, attributable to reduced viability of extracellular parasites. Parasites in which TgATP4 had been disrupted showed reduced virulence in mice. These results provide evidence for ATP4 proteins playing a key conserved role in Na+ regulation in apicomplexan parasites.
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Affiliation(s)
- Adele M Lehane
- From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia,
| | - Adelaide S M Dennis
- From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Katherine O Bray
- From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Dongdi Li
- From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Esther Rajendran
- From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - James M McCoy
- the Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC 3052, Australia, and.,the Department of Medical Biology, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Hillary M McArthur
- From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Markus Winterberg
- From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Farid Rahimi
- From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Christopher J Tonkin
- the Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC 3052, Australia, and.,the Department of Medical Biology, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Kiaran Kirk
- From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia,
| | - Giel G van Dooren
- From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia,
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57
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Veale CGL. Unpacking the Pathogen Box-An Open Source Tool for Fighting Neglected Tropical Disease. ChemMedChem 2019; 14:386-453. [PMID: 30614200 DOI: 10.1002/cmdc.201800755] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Indexed: 12/13/2022]
Abstract
The Pathogen Box is a 400-strong collection of drug-like compounds, selected for their potential against several of the world's most important neglected tropical diseases, including trypanosomiasis, leishmaniasis, cryptosporidiosis, toxoplasmosis, filariasis, schistosomiasis, dengue virus and trichuriasis, in addition to malaria and tuberculosis. This library represents an ensemble of numerous successful drug discovery programmes from around the globe, aimed at providing a powerful resource to stimulate open source drug discovery for diseases threatening the most vulnerable communities in the world. This review seeks to provide an in-depth analysis of the literature pertaining to the compounds in the Pathogen Box, including structure-activity relationship highlights, mechanisms of action, related compounds with reported activity against different diseases, and, where appropriate, discussion on the known and putative targets of compounds, thereby providing context and increasing the accessibility of the Pathogen Box to the drug discovery community.
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Affiliation(s)
- Clinton G L Veale
- School of Chemistry and Physics, Pietermaritzburg Campus, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209, South Africa
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58
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Bioinformatics Analysis and Functional Prediction of Transmembrane Proteins in Entamoeba histolytica. Genes (Basel) 2018; 9:genes9100499. [PMID: 30332795 PMCID: PMC6209943 DOI: 10.3390/genes9100499] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 09/09/2018] [Accepted: 09/12/2018] [Indexed: 12/18/2022] Open
Abstract
Entamoeba histolytica is an invasive, pathogenic parasite causing amoebiasis. Given that proteins involved in transmembrane (TM) transport are crucial for the adherence, invasion, and nutrition of the parasite, we conducted a genome-wide bioinformatics analysis of encoding proteins to functionally classify and characterize all the TM proteins in E. histolytica. In the present study, 692 TM proteins have been identified, of which 546 are TM transporters. For the first time, we report a set of 141 uncharacterized proteins predicted as TM transporters. The percentage of TM proteins was found to be lower in comparison to the free-living eukaryotes, due to the extracellular nature and functional diversification of the TM proteins. The number of multi-pass proteins is larger than the single-pass proteins; though both have their own significance in parasitism, multi-pass proteins are more extensively required as these are involved in acquiring nutrition and for ion transport, while single-pass proteins are only required at the time of inciting infection. Overall, this intestinal parasite implements multiple mechanisms for establishing infection, obtaining nutrition, and adapting itself to the new host environment. A classification of the repertoire of TM transporters in the present study augments several hints on potential methods of targeting the parasite for therapeutic benefits.
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59
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Radke JB, Burrows JN, Goldberg DE, Sibley LD. Evaluation of Current and Emerging Antimalarial Medicines for Inhibition of Toxoplasma gondii Growth in Vitro. ACS Infect Dis 2018; 4:1264-1274. [PMID: 29998728 PMCID: PMC6093624 DOI: 10.1021/acsinfecdis.8b00113] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Toxoplasma gondii is a common zoonotic infection of humans, and estimates indicate that 1-2 billion people are chronically infected. Although largely asymptomatic, chronic infection poses risk of serious disease due to reactivation should immunity decline. Current therapies for toxoplasmosis only control acute infection caused by actively proliferating tachyzoites but do not eradicate the chronic tissue cyst stages. As well, there are considerable adverse side effects of the most commonly used therapy of combined sulfadiazine and pyrimethamine. Targeting the folate pathway is also an effective treatment for malaria, caused by the related parasites Plasmodium spp., suggesting common agents might be used to treat both infections. Here, we evaluated currently approved and newly emerging medicines for malaria to determine if such compounds might also prove useful for treating toxoplasmosis. Surprisingly, the majority of antimalarial compounds being used currently or in development for treatment of malaria were only modestly effective at inhibiting in vitro growth of T. gondii tachyzoites. These findings suggest that many essential processes in P. falciparum that are targeted by antimalarial compounds are either divergent or nonessential in T. gondii, thus limiting options for repurposing of current antimalarial medicines for toxoplasmosis.
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Affiliation(s)
- Joshua B. Radke
- Department of Molecular Microbiology, Washington University Sch. Med., 600 S. Euclid Ave., St Louis, MO 63110
| | - Jeremy N. Burrows
- Medicines for Malaria Venture, ICC, Route de Pré3Bois 20, 1215 Geneva, Switzerland
| | - Daniel E. Goldberg
- Departments of Medicine and Molecular Microbiology, Washington University Sch. Med., 660 S. Euclid Ave., St Louis, MO 63110
| | - L. David Sibley
- Department of Molecular Microbiology, Washington University Sch. Med., 600 S. Euclid Ave., St Louis, MO 63110
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60
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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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61
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Rosling JEO, Ridgway MC, Summers RL, Kirk K, Lehane AM. Biochemical characterization and chemical inhibition of PfATP4-associated Na +-ATPase activity in Plasmodium falciparum membranes. J Biol Chem 2018; 293:13327-13337. [PMID: 29986883 DOI: 10.1074/jbc.ra118.003640] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 06/26/2018] [Indexed: 11/06/2022] Open
Abstract
The antimalarial activity of chemically diverse compounds, including the clinical candidate cipargamin, has been linked to the ATPase PfATP4 in the malaria-causing parasite Plasmodium falciparum The characterization of PfATP4 has been hampered by the inability thus far to achieve its functional expression in a heterologous system. Here, we optimized a membrane ATPase assay to probe the function of PfATP4 and its chemical sensitivity. We found that cipargamin inhibited the Na+-dependent ATPase activity present in P. falciparum membranes from WT parasites and that its potency was reduced in cipargamin-resistant PfATP4-mutant parasites. The cipargamin-sensitive fraction of membrane ATPase activity was inhibited by all 28 of the compounds in the "Malaria Box" shown previously to disrupt ion regulation in P. falciparum in a cipargamin-like manner. This is consistent with PfATP4 being the direct target of these compounds. Characterization of the cipargamin-sensitive ATPase activity yielded data consistent with PfATP4 being a Na+ transporter that is sensitive to physiologically relevant perturbations of pH, but not of [K+] or [Ca2+]. With an apparent Km for ATP of 0.2 mm and an apparent Km for Na+ of 16-17 mm, the protein is predicted to operate at below its half-maximal rate under normal physiological conditions, allowing the rate of Na+ efflux to increase in response to an increase in cytosolic [Na+]. In membranes from a cipargamin-resistant PfATP4-mutant line, the apparent Km for Na+ is slightly elevated. Our study provides new insights into the biochemical properties and chemical sensitivity of an important new antimalarial drug target.
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Affiliation(s)
- James E O Rosling
- From the Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Melanie C Ridgway
- From the Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Robert L Summers
- From the Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Kiaran Kirk
- From the Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Adele M Lehane
- From the Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
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62
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Dennis ASM, Rosling JEO, Lehane AM, Kirk K. Diverse antimalarials from whole-cell phenotypic screens disrupt malaria parasite ion and volume homeostasis. Sci Rep 2018; 8:8795. [PMID: 29892073 PMCID: PMC5995868 DOI: 10.1038/s41598-018-26819-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 05/14/2018] [Indexed: 11/17/2022] Open
Abstract
Four hundred structurally diverse drug-like compounds comprising the Medicines for Malaria Venture's 'Pathogen Box' were screened for their effect on a range of physiological parameters in asexual blood-stage malaria (Plasmodium falciparum) parasites. Eleven of these compounds were found to perturb parasite Na+, pH and volume in a manner consistent with inhibition of the putative Na+ efflux P-type ATPase PfATP4. All eleven compounds fell within the subset of 125 compounds included in the Pathogen Box on the basis of their having been identified as potent inhibitors of the growth of asexual blood-stage P. falciparum parasites. All eleven compounds inhibited the Na+-dependent ATPase activity of parasite membranes and showed reduced efficacy against parasites carrying mutations in PfATP4. This study increases the number of chemically diverse structures known to show a 'PfATP4-associated' phenotype, and adds to emerging evidence that a high proportion (7-9%) of the structurally diverse antimalarial compounds identified in whole cell phenotypic screens share the same mechanism of action, exerting their antimalarial effect via an interaction with PfATP4.
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Affiliation(s)
- Adelaide S M Dennis
- Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - James E O Rosling
- Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Adele M Lehane
- Research School of Biology, Australian National University, Canberra, ACT 2601, Australia.
| | - Kiaran Kirk
- Research School of Biology, Australian National University, Canberra, ACT 2601, Australia.
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63
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Abstract
The last two decades have seen a surge in antimalarial drug development with product development partnerships taking a leading role. Resistance of Plasmodium falciparum to the artemisinin derivatives, piperaquine and mefloquine in Southeast Asia means new antimalarials are needed with some urgency. There are at least 13 agents in clinical development. Most of these are blood schizonticides for the treatment of uncomplicated falciparum malaria, under evaluation either singly or as part of two-drug combinations. Leading candidates progressing through the pipeline are artefenomel-ferroquine and lumefantrine-KAF156, both in Phase 2b. Treatment of severe malaria continues to rely on two parenteral drugs with ancient forebears: artesunate and quinine, with sevuparin being evaluated as an adjuvant therapy. Tafenoquine is under review by stringent regulatory authorities for approval as a single-dose treatment for Plasmodium vivax relapse prevention. This represents an advance over standard 14-day primaquine regimens; however, the risk of acute haemolytic anaemia in patients with glucose-6-phosphate dehydrogenase deficiency remains. For disease prevention, several of the newer agents show potential but are unlikely to be recommended for use in the main target groups of pregnant women and young children for some years. Latest predictions are that the malaria burden will continue to be high in the coming decades. This fact, coupled with the repeated loss of antimalarials to resistance, indicates that new antimalarials will be needed for years to come. Failure of the artemisinin-based combinations in Southeast Asia has stimulated a reappraisal of current approaches to combination therapy for malaria with incorporation of three or more drugs in a single treatment under consideration.
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Affiliation(s)
- Elizabeth A Ashley
- Myanmar Oxford Clinical Research Unit, Yangon, Myanmar.
- Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK.
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64
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Cell Swelling Induced by the Antimalarial KAE609 (Cipargamin) and Other PfATP4-Associated Antimalarials. Antimicrob Agents Chemother 2018; 62:AAC.00087-18. [PMID: 29555632 DOI: 10.1128/aac.00087-18] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 02/18/2018] [Indexed: 12/15/2022] Open
Abstract
For an increasing number of antimalarial agents identified in high-throughput phenotypic screens, there is evidence that they target PfATP4, a putative Na+ efflux transporter on the plasma membrane of the human malaria parasite Plasmodium falciparum For several such "PfATP4-associated" compounds, it has been noted that their addition to parasitized erythrocytes results in cell swelling. Here we show that six structurally diverse PfATP4-associated compounds, including the clinical candidate KAE609 (cipargamin), induce swelling of both isolated blood-stage parasites and intact parasitized erythrocytes. The swelling of isolated parasites is dependent on the presence of Na+ in the external environment and may be attributed to the osmotic consequences of Na+ uptake. The swelling of the parasitized erythrocyte results in an increase in its osmotic fragility. Countering cell swelling by increasing the osmolarity of the extracellular medium reduces the antiplasmodial efficacy of PfATP4-associated compounds, consistent with cell swelling playing a role in the antimalarial activity of this class of compounds.
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65
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Kumar S, Bhardwaj TR, Prasad DN, Singh RK. Drug targets for resistant malaria: Historic to future perspectives. Biomed Pharmacother 2018; 104:8-27. [PMID: 29758416 DOI: 10.1016/j.biopha.2018.05.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 04/22/2018] [Accepted: 05/07/2018] [Indexed: 01/05/2023] Open
Abstract
New antimalarial targets are the prime need for the discovery of potent drug candidates. In order to fulfill this objective, antimalarial drug researches are focusing on promising targets in order to develop new drug candidates. Basic metabolism and biochemical process in the malaria parasite, i.e. Plasmodium falciparum can play an indispensable role in the identification of these targets. But, the emergence of resistance to antimalarial drugs is an escalating comprehensive problem with the progress of antimalarial drug development. The development of resistance has highlighted the need for the search of novel antimalarial molecules. The pharmaceutical industries are committed to new drug development due to the global recognition of this life threatening resistance to the currently available antimalarial therapy. The recent developments in the understanding of parasite biology are exhilarating this resistance issue which is further being ignited by malaria genome project. With this background of information, this review was aimed to highlights and provides useful information on various present and promising treatment approaches for resistant malaria, new progresses, pursued by some innovative targets that have been explored till date. This review also discusses modern and futuristic multiple approaches to antimalarial drug discovery and development with pictorial presentations highlighting the various targets, that could be exploited for generating promising new drugs in the future for drug resistant malaria.
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Affiliation(s)
- Sahil Kumar
- School of Pharmacy and Emerging Sciences, Baddi University of Emerging Sciences & Technology, Baddi, Dist. Solan, 173205, Himachal Pradesh, India
| | - T R Bhardwaj
- School of Pharmacy and Emerging Sciences, Baddi University of Emerging Sciences & Technology, Baddi, Dist. Solan, 173205, Himachal Pradesh, India
| | - D N Prasad
- Department of Pharmaceutical Chemistry, Shivalik College of Pharmacy, Nangal, Dist. Rupnagar, 140126, Punjab, India
| | - Rajesh K Singh
- Department of Pharmaceutical Chemistry, Shivalik College of Pharmacy, Nangal, Dist. Rupnagar, 140126, Punjab, India.
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Benzoxazine derivatives of phytophenols show anti-plasmodial activity via sodium homeostasis disruption. Bioorg Med Chem Lett 2018; 28:1629-1637. [DOI: 10.1016/j.bmcl.2018.03.047] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 03/17/2018] [Accepted: 03/17/2018] [Indexed: 12/21/2022]
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67
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Gerry CJ, Schreiber SL. Chemical probes and drug leads from advances in synthetic planning and methodology. Nat Rev Drug Discov 2018; 17:333-352. [PMID: 29651105 PMCID: PMC6707071 DOI: 10.1038/nrd.2018.53] [Citation(s) in RCA: 143] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Screening of small-molecule libraries is a productive method for identifying both chemical probes of disease-related targets and potential starting points for drug discovery. In this article, we focus on strategies such as diversity-oriented synthesis that aim to explore novel areas of chemical space efficiently by populating small-molecule libraries with compounds containing structural features that are typically under-represented in commercially available screening collections. Drawing from more than a decade's worth of examples, we highlight how the design and synthesis of such libraries have been enabled by modern synthetic chemistry, and we illustrate the impact of the resultant chemical probes and drug leads in a wide range of diseases.
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Affiliation(s)
- Christopher J Gerry
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- The Broad Institute of Harvard & MIT, Cambridge, MA, USA
| | - Stuart L Schreiber
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- The Broad Institute of Harvard & MIT, Cambridge, MA, USA
- Howard Hughes Medical Institute, Cambridge, MA, USA
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68
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Using Yeast Synthetic Lethality To Inform Drug Combination for Malaria. Antimicrob Agents Chemother 2018; 62:AAC.01533-17. [PMID: 29358287 PMCID: PMC5913926 DOI: 10.1128/aac.01533-17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 12/30/2017] [Indexed: 11/28/2022] Open
Abstract
Combinatorial chemotherapy is necessary for the treatment of malaria. However, finding a suitable partner drug for a new candidate is challenging. Here we develop an algorithm that identifies all of the gene pairs of Plasmodium falciparum that possess orthologues in yeast that have a synthetic lethal interaction but are absent in humans. This suggests new options for drug combinations, particularly for inhibitors of targets such as P. falciparum calcineurin, cation ATPase 4, or phosphatidylinositol 4-kinase.
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69
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Meier A, Erler H, Beitz E. Targeting Channels and Transporters in Protozoan Parasite Infections. Front Chem 2018; 6:88. [PMID: 29637069 PMCID: PMC5881087 DOI: 10.3389/fchem.2018.00088] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Accepted: 03/12/2018] [Indexed: 12/25/2022] Open
Abstract
Infectious diseases caused by pathogenic protozoa are among the most significant causes of death in humans. Therapeutic options are scarce and massively challenged by the emergence of resistant parasite strains. Many of the current anti-parasite drugs target soluble enzymes, generate unspecific oxidative stress, or act by an unresolved mechanism within the parasite. In recent years, collections of drug-like compounds derived from large-scale phenotypic screenings, such as the malaria or pathogen box, have been made available to researchers free of charge boosting the identification of novel promising targets. Remarkably, several of the compound hits have been found to inhibit membrane proteins at the periphery of the parasites, i.e., channels and transporters for ions and metabolites. In this review, we will focus on the progress made on targeting channels and transporters at different levels and the potential for use against infections with apicomplexan parasites mainly Plasmodium spp. (malaria) and Toxoplasma gondii (toxoplasmosis), with kinetoplastids Trypanosoma brucei (sleeping sickness), Trypanosoma cruzi (Chagas disease), and Leishmania ssp. (leishmaniasis), and the amoeba Entamoeba histolytica (amoebiasis).
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Affiliation(s)
- Anna Meier
- Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Holger Erler
- Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Eric Beitz
- Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-University of Kiel, Kiel, Germany
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70
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Luth MR, Gupta P, Ottilie S, Winzeler EA. Using in Vitro Evolution and Whole Genome Analysis To Discover Next Generation Targets for Antimalarial Drug Discovery. ACS Infect Dis 2018; 4:301-314. [PMID: 29451780 PMCID: PMC5848146 DOI: 10.1021/acsinfecdis.7b00276] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
![]()
Although
many new anti-infectives have been discovered and developed solely
using phenotypic cellular screening and assay optimization, most researchers
recognize that structure-guided drug design is more practical and
less costly. In addition, a greater chemical space can be interrogated
with structure-guided drug design. The practicality of structure-guided
drug design has launched a search for the targets of compounds discovered
in phenotypic screens. One method that has been used extensively in
malaria parasites for target discovery and chemical validation is in vitro evolution and whole genome analysis (IVIEWGA).
Here, small molecules from phenotypic screens with demonstrated antiparasitic
activity are used in genome-based target discovery methods. In this
Review, we discuss the newest, most promising druggable targets discovered
or further validated by evolution-based methods, as well as some exceptions.
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Affiliation(s)
- Madeline R. Luth
- Division of Host Pathogen Systems and Therapeutics, Department of Pediatrics, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Purva Gupta
- Division of Host Pathogen Systems and Therapeutics, Department of Pediatrics, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Sabine Ottilie
- Division of Host Pathogen Systems and Therapeutics, Department of Pediatrics, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Elizabeth A. Winzeler
- Division of Host Pathogen Systems and Therapeutics, Department of Pediatrics, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
- Skaggs School of Pharmaceutical Sciences, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
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Okombo J, Chibale K. Recent updates in the discovery and development of novel antimalarial drug candidates. MEDCHEMCOMM 2018; 9:437-453. [PMID: 30108934 PMCID: PMC6071755 DOI: 10.1039/c7md00637c] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Accepted: 02/02/2018] [Indexed: 01/20/2023]
Abstract
Though morbidity and mortality due to malaria have declined in the last 15 years, emerging resistance to first-line artemisinin-based antimalarials, absence of efficacious vaccines and limited chemotherapeutic alternatives imperil the consolidation of these gains. As a blueprint to steer future designs of new medicines, malaria drug discovery recently adopted a descriptive proposal for the ideal candidate molecules and drugs likely to successfully progress into the final stages of clinical development. As an audit of recent developments in the chemotherapy of malaria in the last five years, this review captures a landscape of diverse molecules at various stages of drug development and discusses their progress. In brief, we also discuss how omics data on Plasmodium has been extensively leveraged to identify potential vaccine candidates and putative targets of molecules in development and clinical use as well as map loci implicit in their modes of resistance. Future perspective on malaria drug development should involve a reconciliation of some of the challenges of the target candidate profiles (TCPs), specifically TCP3, with the promise of effective anti-hypnozoite medicines. Similarly, with the recent development of a humanized mouse model that can evaluate the prophylactic potential of candidate drugs, we argue for increased effort at identifying more liver-stage molecules, which are often only secondarily prioritized in conventional screening programs.
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Affiliation(s)
- John Okombo
- Department of Chemistry , University of Cape Town , Rondebosch 7701 , South Africa .
| | - Kelly Chibale
- Department of Chemistry , University of Cape Town , Rondebosch 7701 , South Africa .
- South African Medical Research Council Drug Discovery and Development Research Unit , Department of Chemistry and Institute of Infectious Disease and Molecular Medicine , University of Cape Town , Rondebosch 7701 , South Africa
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Targeted Phenotypic Screening in Plasmodium falciparum and Toxoplasma gondii Reveals Novel Modes of Action of Medicines for Malaria Venture Malaria Box Molecules. mSphere 2018; 3:mSphere00534-17. [PMID: 29359192 PMCID: PMC5770543 DOI: 10.1128/msphere.00534-17] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 12/20/2017] [Indexed: 01/23/2023] Open
Abstract
The Malaria Box collection includes 400 chemically diverse small molecules with documented potency against malaria parasite growth, but the underlying modes of action are largely unknown. Using complementary phenotypic screens against Plasmodium falciparum and Toxoplasma gondii, we report phenotype-specific hits based on inhibition of overall parasite growth, apicoplast segregation, and egress or host invasion, providing hitherto unavailable insights into the possible mechanisms affected. First, the Malaria Box library was screened against tachyzoite stage T. gondii and the half-maximal effective concentrations (EC50s) of molecules showing ≥80% growth inhibition at 10 µM were determined. Comparison of the EC50s for T. gondii and P. falciparum identified a subset of 24 molecules with nanomolar potency against both parasites. Thirty molecules that failed to induce acute growth inhibition in T. gondii tachyzoites in a 2-day assay caused delayed parasite death upon extended exposure, with at least three molecules interfering with apicoplast segregation during daughter cell formation. Using flow cytometry and microscopy-based examinations, we prioritized 26 molecules with the potential to inhibit host cell egress/invasion during asexual developmental stages of P. falciparum. None of the inhibitors affected digestive vacuole integrity, ruling out a mechanism mediated by broadly specific protease inhibitor activity. Interestingly, five of the plasmodial egress inhibitors inhibited ionophore-induced egress of T. gondii tachyzoites. These findings highlight the advantage of comparative and targeted phenotypic screens in related species as a means to identify lead molecules with a conserved mode of action. Further work on target identification and mechanism analysis will facilitate the development of antiparasitic compounds with cross-species efficacy. IMPORTANCE The phylum Apicomplexa includes many human and animal pathogens, such as Plasmodium falciparum (human malaria) and Toxoplasma gondii (human and animal toxoplasmosis). Widespread resistance to current antimalarials and the lack of a commercial vaccine necessitate novel pharmacological interventions with distinct modes of action against malaria. For toxoplasmosis, new drugs to effectively eliminate tissue-dwelling latent cysts of the parasite are needed. The Malaria Box antimalarial collection, managed and distributed by the Medicines for Malaria Venture, includes molecules of novel chemical classes with proven antimalarial efficacy. Using targeted phenotypic assays of P. falciparum and T. gondii, we have identified a subset of the Malaria Box molecules as potent inhibitors of plastid segregation and parasite invasion and egress, thereby providing early insights into their probable mode of action. Five molecules that inhibit the egress of both parasites have been identified for further mechanistic studies. Thus, the approach we have used to identify novel molecules with defined modes of action in multiple parasites can expedite the development of pan-active antiparasitic agents.
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Bublitz M, Kjellerup L, Cohrt KO, Gordon S, Mortensen AL, Clausen JD, Pallin TD, Hansen JB, Fuglsang AT, Dalby-Brown W, Winther AML. Tetrahydrocarbazoles are a novel class of potent P-type ATPase inhibitors with antifungal activity. PLoS One 2018; 13:e0188620. [PMID: 29293507 PMCID: PMC5749684 DOI: 10.1371/journal.pone.0188620] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 11/10/2017] [Indexed: 11/19/2022] Open
Abstract
We have identified a series of tetrahydrocarbazoles as novel P-type ATPase inhibitors. Using a set of rationally designed analogues, we have analyzed their structure-activity relationship using functional assays, crystallographic data and computational modeling. We found that tetrahydrocarbazoles inhibit adenosine triphosphate (ATP) hydrolysis of the fungal H+-ATPase, depolarize the fungal plasma membrane and exhibit broad-spectrum antifungal activity. Comparative inhibition studies indicate that many tetrahydrocarbazoles also inhibit the mammalian Ca2+-ATPase (SERCA) and Na+,K+-ATPase with an even higher potency than Pma1. We have located the binding site for this compound class by crystallographic structure determination of a SERCA-tetrahydrocarbazole complex to 3.0 Å resolution, finding that the compound binds to a region above the ion inlet channel of the ATPase. A homology model of the Candida albicans H+-ATPase based on this crystal structure, indicates that the compounds could bind to the same pocket and identifies pocket extensions that could be exploited for selectivity enhancement. The results of this study will aid further optimization towards selective H+-ATPase inhibitors as a new class of antifungal agents.
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Affiliation(s)
- Maike Bublitz
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Lasse Kjellerup
- Pcovery, Copenhagen N, Denmark
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | | | | | | | | | | | | | - Anja Thoe Fuglsang
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
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Okour M, Derimanov G, Barnett R, Fernandez E, Ferrer S, Gresham S, Hossain M, Gamo FJ, Koh G, Pereira A, Rolfe K, Wong D, Young G, Rami H, Haselden J. A human microdose study of the antimalarial drug GSK3191607 in healthy volunteers. Br J Clin Pharmacol 2017; 84:482-489. [PMID: 29168205 DOI: 10.1111/bcp.13476] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 10/07/2017] [Accepted: 11/14/2017] [Indexed: 01/03/2023] Open
Abstract
AIMS GSK3191607, a novel inhibitor of the Plasmodium falciparum ATP4 (PfATP4) pathway, is being considered for development in humans. However, a key problem encountered during the preclinical evaluation of the compound was its inconsistent pharmacokinetic (PK) profile across preclinical species (mouse, rat and dog), which prevented reliable prediction of PK parameters in humans and precluded a well-founded assessment of the potential for clinical development of the compound. Therefore, an open-label microdose (100 μg, six subjects) first time in humans study was conducted to assess the human PK of GSK3191607 following intravenous administration of [14C]-GSK3191607. METHODS A human microdose study was conducted to investigate the clinical PK of GSK3191607 and enable a Go/No Go decision on further progression of the compound. The PK disposition parameters estimated from the microdose study, combined with preclinical in vitro and in vivo pharmacodynamic parameters, were all used to estimate the potential efficacy of various oral dosing regimens in humans. RESULTS The PK profile, based on the microdose data, demonstrated a half-life (~17 h) similar to other antimalarial compounds currently in clinical development. However, combining the microdose data with the pharmacodynamic data provided results that do not support further clinical development of the compound for a single dose cure. CONCLUSIONS The information generated by this study provides a basis for predicting the expected oral PK profiles of GSK3191607 in man and supports decisions on the future clinical development of the compound.
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Affiliation(s)
- Malek Okour
- Clinical Pharmacology Modeling and Simulation (CPMS), GlaxoSmithKline, King of Prussia, PA, USA
| | - Geo Derimanov
- Discovery Medicine, Diseases of the Developing World, GlaxoSmithKline, Collegeville, PA, USA
| | - Rodger Barnett
- Drug Product Design and Development (DPDD), GlaxoSmithKline, Ware, Herts, UK
| | - Esther Fernandez
- Malaria DPU, Tres Cantos Medicines Development Campus, GlaxoSmithKline, Tres Cantos, Spain
| | - Santiago Ferrer
- Malaria DPU, Tres Cantos Medicines Development Campus, GlaxoSmithKline, Tres Cantos, Spain
| | | | - Mohammad Hossain
- Clinical Pharmacology Modeling and Simulation (CPMS), GlaxoSmithKline, King of Prussia, PA, USA
| | - Francisco-Javier Gamo
- Malaria DPU, Tres Cantos Medicines Development Campus, GlaxoSmithKline, Tres Cantos, Spain
| | - Gavin Koh
- Diseases of the Developing World, GlaxoSmithKline, Stockley Park, Uxbridge, UK
| | - Adrian Pereira
- Bioanalysis, Immunogenicity and Biomarkers (BIB), GlaxoSmithKline, Ware, UK
| | - Katie Rolfe
- Statistics, Programming and Data Strategy (SPDS), GlaxoSmithKline, Stockley Park, Uxbridge, UK
| | - Deborah Wong
- Clinical Pharmacology Science & Study Operations (CPSSO), GlaxoSmithKline, Stevenage, Hertfordshire, UK
| | - Graeme Young
- Bioanalysis, Immunogenicity and Biomarkers (BIB), GlaxoSmithKline, Ware, UK
| | - Harshad Rami
- Diseases of the Developing World, GlaxoSmithKline, Stockley Park, Uxbridge, UK
| | - John Haselden
- Malaria DPU, Tres Cantos Medicines Development Campus, GlaxoSmithKline, Tres Cantos, Spain
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75
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Transmembrane solute transport in the apicomplexan parasite Plasmodium. Emerg Top Life Sci 2017; 1:553-561. [PMID: 33525850 DOI: 10.1042/etls20170097] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Revised: 11/12/2017] [Accepted: 11/16/2017] [Indexed: 12/22/2022]
Abstract
Apicomplexa are a large group of eukaryotic, single-celled parasites, with complex life cycles that occur within a wide range of different microenvironments. They include important human pathogens such as Plasmodium, the causal agent of malaria, and Toxoplasma, which causes toxoplasmosis most often in immunocompromised individuals. Despite environmental differences in their life cycles, these parasites retain the ability to obtain nutrients, remove waste products, and control ion balances. They achieve this flexibility by relying on proteins that can deliver and remove solutes. This reliance on transport proteins for essential functions makes these pathways excellent potential targets for drug development programmes. Transport proteins are frequently key mediators of drug resistance by their ability to remove drugs from their sites of action. The study of transport processes mediated by integral membrane proteins and, in particular, identification of their physiological functions and localisation, and differentiation from host orthologues has already established new validated drug targets. Our understanding of how apicomplexan parasites have adapted to changing environmental challenges has also increased through the study of their transporters. This brief introduction to membrane transporters of apicomplexans highlights recent discoveries focusing on Plasmodium and emphasises future directions.
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Sayers CP, Mollard V, Buchanan HD, McFadden GI, Goodman CD. A genetic screen in rodent malaria parasites identifies five new apicoplast putative membrane transporters, one of which is essential in human malaria parasites. Cell Microbiol 2017; 20. [DOI: 10.1111/cmi.12789] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 09/04/2017] [Accepted: 09/07/2017] [Indexed: 11/30/2022]
Affiliation(s)
- Claire P. Sayers
- School of BioSciences University of Melbourne Parkville Victoria Australia
| | - Vanessa Mollard
- School of BioSciences University of Melbourne Parkville Victoria Australia
| | - Hayley D. Buchanan
- School of BioSciences University of Melbourne Parkville Victoria Australia
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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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Abstract
Malaria is caused in humans by five species of single-celled eukaryotic Plasmodium parasites (mainly Plasmodium falciparum and Plasmodium vivax) that are transmitted by the bite of Anopheles spp. mosquitoes. Malaria remains one of the most serious infectious diseases; it threatens nearly half of the world's population and led to hundreds of thousands of deaths in 2015, predominantly among children in Africa. Malaria is managed through a combination of vector control approaches (such as insecticide spraying and the use of insecticide-treated bed nets) and drugs for both treatment and prevention. The widespread use of artemisinin-based combination therapies has contributed to substantial declines in the number of malaria-related deaths; however, the emergence of drug resistance threatens to reverse this progress. Advances in our understanding of the underlying molecular basis of pathogenesis have fuelled the development of new diagnostics, drugs and insecticides. Several new combination therapies are in clinical development that have efficacy against drug-resistant parasites and the potential to be used in single-dose regimens to improve compliance. This ambitious programme to eliminate malaria also includes new approaches that could yield malaria vaccines or novel vector control strategies. However, despite these achievements, a well-coordinated global effort on multiple fronts is needed if malaria elimination is to be achieved.
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Affiliation(s)
- Margaret A Phillips
- Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9038, USA
| | | | | | | | - Wesley C Van Voorhis
- University of Washington, Department of Medicine, Division of Allergy and Infectious Diseases, Center for Emerging and Re-emerging Infectious Diseases, Seattle, Washington, USA
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Rai P, Sharma D, Soni R, Khatoon N, Sharma B, Bhatt TK. Plasmodium falciparum apicoplast and its transcriptional regulation through calcium signaling. J Microbiol 2017; 55:231-236. [DOI: 10.1007/s12275-017-6525-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 12/23/2016] [Accepted: 12/23/2016] [Indexed: 12/12/2022]
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Hapuarachchi SV, Cobbold SA, Shafik SH, Dennis ASM, McConville MJ, Martin RE, Kirk K, Lehane AM. The Malaria Parasite's Lactate Transporter PfFNT Is the Target of Antiplasmodial Compounds Identified in Whole Cell Phenotypic Screens. PLoS Pathog 2017; 13:e1006180. [PMID: 28178359 PMCID: PMC5298231 DOI: 10.1371/journal.ppat.1006180] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 01/11/2017] [Indexed: 11/19/2022] Open
Abstract
In this study the ‘Malaria Box’ chemical library comprising 400 compounds with antiplasmodial activity was screened for compounds that perturb the internal pH of the malaria parasite, Plasmodium falciparum. Fifteen compounds induced an acidification of the parasite cytosol. Two of these did so by inhibiting the parasite’s formate nitrite transporter (PfFNT), which mediates the H+-coupled efflux from the parasite of lactate generated by glycolysis. Both compounds were shown to inhibit lactate transport across the parasite plasma membrane, and the transport of lactate by PfFNT expressed in Xenopus laevis oocytes. PfFNT inhibition caused accumulation of lactate in parasitised erythrocytes, and swelling of both the parasite and parasitised erythrocyte. Long-term exposure of parasites to one of the inhibitors gave rise to resistant parasites with a mutant form of PfFNT that showed reduced inhibitor sensitivity. This study provides the first evidence that PfFNT is a druggable antimalarial target. The emergence and spread of Plasmodium falciparum strains resistant to leading antimalarial drugs has intensified the need to discover and develop drugs that kill the parasite via new mechanisms. Here we screened compounds that are known to inhibit P. falciparum growth for their effects on the pH inside the parasite. We identified fifteen compounds that decrease the pH inside the parasite, and determined the mechanism by which two of these, MMV007839 and MMV000972, disrupt pH and kill the parasite. The two compounds were found to inhibit the P. falciparum formate nitrite transporter (PfFNT), a transport protein that is located on the parasite surface and that serves to remove the waste product lactic acid from the parasite. The compounds inhibited both the H+-coupled transport of lactate across the parasite plasma membrane and the transport of lactate by PfFNT expressed in Xenopus oocytes. In addition to disrupting pH, PfFNT inhibition led to a build-up of lactate in the parasite-infected red blood cell and the swelling of both the parasite and the infected red blood cell. Exposing parasites to MMV007839 over a prolonged time period gave rise to resistant parasites with a mutant form of PfFNT that was less sensitive to the compound. This study validates PfFNT as a novel antimalarial drug target.
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Affiliation(s)
| | - Simon A Cobbold
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, VIC, Australia
| | - Sarah H Shafik
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Adelaide S M Dennis
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Malcolm J McConville
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, VIC, Australia
| | - Rowena E Martin
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Kiaran Kirk
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Adele M Lehane
- Research School of Biology, Australian National University, Canberra, ACT, Australia
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Tools for attenuation of gene expression in malaria parasites. Int J Parasitol 2017; 47:385-398. [PMID: 28153780 DOI: 10.1016/j.ijpara.2016.11.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 09/15/2016] [Accepted: 11/28/2016] [Indexed: 12/30/2022]
Abstract
An understanding of the biology of Plasmodium parasites, which are the causative agents of the disease malaria, requires study of gene function. Various reverse genetic tools have been described for determining gene function. These tools can be broadly grouped as trans- and cis-acting. Trans-acting tools control gene functions through synthetic nucleic acid probe molecules matching the sequence of the gene of interest. Once delivered to the parasite, the probe engages with the mRNA of the target gene and attenuates its function. Cis-acting tools control gene function through elements introduced into the gene of interest by DNA transfection. The expression of the modified gene can be controlled using external agents, typically small molecule ligands. In this review, we discuss the strengths and weaknesses of these tools to guide researchers in selecting the appropriate tool for studies of gene function, and for guiding future refinements of these tools.
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82
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Estimation of the In Vivo MIC of Cipargamin in Uncomplicated Plasmodium falciparum Malaria. Antimicrob Agents Chemother 2017; 61:AAC.01940-16. [PMID: 27872070 PMCID: PMC5278730 DOI: 10.1128/aac.01940-16] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 11/10/2016] [Indexed: 01/29/2023] Open
Abstract
The MIC of an antimalarial drug for a particular infection is the drug level associated with a net parasite multiplication rate of one per asexual cycle. To ensure the cure of malaria, the MIC must be exceeded until all parasites have been eliminated. The development of highly sensitive and accurate PCR quantitation of low-density malaria parasitemia enables the prospective pharmacokinetic-pharmacodynamic (PK-PD) characterization of antimalarial drug effects and now allows identification of the in vivo MIC. An adaptive design and a PK-PD modeling approach were used to determine prospectively the MIC of the new antimalarial cipargamin (KAE609) in adults with uncomplicated Plasmodium falciparum malaria in an open-label, dose-ranging phase 2a study. Vietnamese adults with acute P. falciparum malaria were allocated sequentially to treatment with a single 30-mg (n = 6), 20-mg (n = 5), 10-mg (n = 7), or 15-mg (n = 7) dose of cipargamin. Artemisinin-based combination therapy was given after parasite densities had fallen and then risen as cipargamin levels declined below the MIC but before a return of signs or symptoms. The rates of parasite clearance were dose dependent, with near saturation of the effect being seen at an adult dose of 30 mg. The developed PK-PD model accurately predicted the therapeutic responses in 23/25 patients. The predicted median in vivo MIC was 0.126 ng/ml (range, 0.038 to 0.803 ng/ml). Pharmacometric characterization of the relationship between antimalarial drug concentrations and parasite clearance rates following graded subtherapeutic antimalarial drug dosing is safe and provides a rational framework for dose finding in antimalarial drug development. (This study has been registered at ClinicalTrials.gov under identifier NCT01836458.)
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83
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Hewitt SN, Dranow DM, Horst BG, Abendroth JA, Forte B, Hallyburton I, Jansen C, Baragaña B, Choi R, Rivas KL, Hulverson MA, Dumais M, Edwards TE, Lorimer DD, Fairlamb AH, Gray DW, Read KD, Lehane AM, Kirk K, Myler PJ, Wernimont A, Walpole C, Stacy R, Barrett LK, Gilbert IH, Van Voorhis WC. Biochemical and Structural Characterization of Selective Allosteric Inhibitors of the Plasmodium falciparum Drug Target, Prolyl-tRNA-synthetase. ACS Infect Dis 2017; 3:34-44. [PMID: 27798837 PMCID: PMC5241706 DOI: 10.1021/acsinfecdis.6b00078] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Plasmodium falciparum (Pf) prolyl-tRNA synthetase (ProRS) is one of the few chemical-genetically validated drug targets for malaria, yet highly selective inhibitors have not been described. In this paper, approximately 40,000 compounds were screened to identify compounds that selectively inhibit PfProRS enzyme activity versus Homo sapiens (Hs) ProRS. X-ray crystallography structures were solved for apo, as well as substrate- and inhibitor-bound forms of PfProRS. We identified two new inhibitors of PfProRS that bind outside the active site. These two allosteric inhibitors showed >100 times specificity for PfProRS compared to HsProRS, demonstrating this class of compounds could overcome the toxicity related to HsProRS inhibition by halofuginone and its analogues. Initial medicinal chemistry was performed on one of the two compounds, guided by the cocrystallography of the compound with PfProRS, and the results can instruct future medicinal chemistry work to optimize these promising new leads for drug development against malaria.
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Affiliation(s)
- Stephen Nakazawa Hewitt
- Center for Emerging
and Reemerging Infectious Disease (CERID), University of Washington, 750 Republican Street, Seattle, Washington 98109, United States
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, Washington 98109, United States
| | - David M. Dranow
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, Washington 98109, United States
- Beryllium Discovery Corporation, 7869 N.E. Day Road West, Bainbridge Island, Washington 98110, United States
| | - Benjamin G. Horst
- Center for Emerging
and Reemerging Infectious Disease (CERID), University of Washington, 750 Republican Street, Seattle, Washington 98109, United States
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, Washington 98109, United States
| | - Jan A. Abendroth
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, Washington 98109, United States
- Beryllium Discovery Corporation, 7869 N.E. Day Road West, Bainbridge Island, Washington 98110, United States
| | - Barbara Forte
- Drug Discovery Unit (DDU), Division of Biological Chemistry and Drug
Discovery, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Irene Hallyburton
- Drug Discovery Unit (DDU), Division of Biological Chemistry and Drug
Discovery, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Chimed Jansen
- Drug Discovery Unit (DDU), Division of Biological Chemistry and Drug
Discovery, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Beatriz Baragaña
- Drug Discovery Unit (DDU), Division of Biological Chemistry and Drug
Discovery, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Ryan Choi
- Center for Emerging
and Reemerging Infectious Disease (CERID), University of Washington, 750 Republican Street, Seattle, Washington 98109, United States
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, Washington 98109, United States
| | - Kasey L. Rivas
- Center for Emerging
and Reemerging Infectious Disease (CERID), University of Washington, 750 Republican Street, Seattle, Washington 98109, United States
| | - Matthew A. Hulverson
- Center for Emerging
and Reemerging Infectious Disease (CERID), University of Washington, 750 Republican Street, Seattle, Washington 98109, United States
| | - Mitchell Dumais
- Center for Emerging
and Reemerging Infectious Disease (CERID), University of Washington, 750 Republican Street, Seattle, Washington 98109, United States
| | - Thomas E. Edwards
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, Washington 98109, United States
- Beryllium Discovery Corporation, 7869 N.E. Day Road West, Bainbridge Island, Washington 98110, United States
| | - Donald D. Lorimer
- Beryllium Discovery Corporation, 7869 N.E. Day Road West, Bainbridge Island, Washington 98110, United States
| | - Alan H. Fairlamb
- Drug Discovery Unit (DDU), Division of Biological Chemistry and Drug
Discovery, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - David W. Gray
- Drug Discovery Unit (DDU), Division of Biological Chemistry and Drug
Discovery, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Kevin D. Read
- Drug Discovery Unit (DDU), Division of Biological Chemistry and Drug
Discovery, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Adele M. Lehane
- Research School of Biology, The Australian National University, Acton, Australian Capital Territory 2601, Australia
| | - Kiaran Kirk
- Research School of Biology, The Australian National University, Acton, Australian Capital Territory 2601, Australia
| | - Peter J. Myler
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, Washington 98109, United States
- Center for Infectious Disease Research, 307 Westlake Avenue North, Suite 500, Seattle, Washington 98109, United States
- Departments of Global Health and Biomedical
Informatics and Medical Education, University of Washington, Seattle, Washington 98195, United States
| | - Amy Wernimont
- Structure-guided Drug Discovery Coalition (SDDC), Structural Genomic Consortium, 101 College Street, MaRS South Tower, Suite 700, Toronto, Ontario M5G 1L7, Canada
| | - Chris Walpole
- Structure-guided Drug Discovery Coalition (SDDC), Structural Genomic Consortium, 101 College Street, MaRS South Tower, Suite 700, Toronto, Ontario M5G 1L7, Canada
| | - Robin Stacy
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, Washington 98109, United States
- Center for Infectious Disease Research, 307 Westlake Avenue North, Suite 500, Seattle, Washington 98109, United States
| | - Lynn K. Barrett
- Center for Emerging
and Reemerging Infectious Disease (CERID), University of Washington, 750 Republican Street, Seattle, Washington 98109, United States
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, Washington 98109, United States
| | - Ian H. Gilbert
- Drug Discovery Unit (DDU), Division of Biological Chemistry and Drug
Discovery, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Wesley C. Van Voorhis
- Center for Emerging
and Reemerging Infectious Disease (CERID), University of Washington, 750 Republican Street, Seattle, Washington 98109, United States
- Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, Washington 98109, United States
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84
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The Rheopathobiology of Plasmodium vivax and Other Important Primate Malaria Parasites. Trends Parasitol 2016; 33:321-334. [PMID: 28040374 DOI: 10.1016/j.pt.2016.11.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 11/17/2016] [Accepted: 11/28/2016] [Indexed: 12/11/2022]
Abstract
Our current understanding of how malaria parasites remodel their host red blood cells (RBCs) and ultimately cause disease is largely based on studies of Plasmodium falciparum. In this review, we expand our knowledge to include what is currently known about pathophysiological changes to RBCs that are infected by non-falciparum malaria parasites. We highlight the potential folly of making generalizations about the rheology of malaria infection, and emphasize the need for more systematic studies into the erythrocytic biology of non-falciparum malaria parasites. We propose that a better understanding of the mechanisms that underlie the changes to RBCs induced by malaria parasites other than P. falciparum may be highly informative for the development of therapeutics that specifically disrupt the altered rheological profile of RBCs infected with either sexual- or asexual-stage parasites, resulting in drugs that block transmission, reduce disease severity, and help delay the onset of resistance to current and future anti-malaria drugs.
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85
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Malaria: Biology and Disease. Cell 2016; 167:610-624. [PMID: 27768886 DOI: 10.1016/j.cell.2016.07.055] [Citation(s) in RCA: 439] [Impact Index Per Article: 54.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 07/17/2016] [Accepted: 07/29/2016] [Indexed: 11/22/2022]
Abstract
Malaria has been a major global health problem of humans through history and is a leading cause of death and disease across many tropical and subtropical countries. Over the last fifteen years renewed efforts at control have reduced the prevalence of malaria by over half, raising the prospect that elimination and perhaps eradication may be a long-term possibility. Achievement of this goal requires the development of new tools including novel antimalarial drugs and more efficacious vaccines as well as an increased understanding of the disease and biology of the parasite. This has catalyzed a major effort resulting in development and regulatory approval of the first vaccine against malaria (RTS,S/AS01) as well as identification of novel drug targets and antimalarial compounds, some of which are in human clinical trials.
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86
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Phillips MA, White KL, Kokkonda S, Deng X, White J, El Mazouni F, Marsh K, Tomchick DR, Manjalanagara K, Rudra KR, Wirjanata G, Noviyanti R, Price RN, Marfurt J, Shackleford DM, Chiu FCK, Campbell M, Jimenez-Diaz MB, Bazaga SF, Angulo-Barturen I, Martinez MS, Lafuente-Monasterio M, Kaminsky W, Silue K, Zeeman AM, Kocken C, Leroy D, Blasco B, Rossignol E, Rueckle T, Matthews D, Burrows JN, Waterson D, Palmer MJ, Rathod PK, Charman SA. A Triazolopyrimidine-Based Dihydroorotate Dehydrogenase Inhibitor with Improved Drug-like Properties for Treatment and Prevention of Malaria. ACS Infect Dis 2016; 2:945-957. [PMID: 27641613 DOI: 10.1021/acsinfecdis.6b00144] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The emergence of drug-resistant malaria parasites continues to hamper efforts to control this lethal disease. Dihydroorotate dehydrogenase has recently been validated as a new target for the treatment of malaria, and a selective inhibitor (DSM265) of the Plasmodium enzyme is currently in clinical development. With the goal of identifying a backup compound to DSM265, we explored replacement of the SF5-aniline moiety of DSM265 with a series of CF3-pyridinyls while maintaining the core triazolopyrimidine scaffold. This effort led to the identification of DSM421, which has improved solubility, lower intrinsic clearance, and increased plasma exposure after oral dosing compared to DSM265, while maintaining a long predicted human half-life. Its improved physical and chemical properties will allow it to be formulated more readily than DSM265. DSM421 showed excellent efficacy in the SCID mouse model of P. falciparum malaria that supports the prediction of a low human dose (<200 mg). Importantly DSM421 showed equal activity against both P. falciparum and P. vivax field isolates, while DSM265 was more active on P. falciparum. DSM421 has the potential to be developed as a single-dose cure or once-weekly chemopreventative for both P. falciparum and P. vivax malaria, leading to its advancement as a preclinical development candidate.
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Affiliation(s)
| | - Karen L. White
- Centre
for Drug Candidate Optimisation, Monash Institute of Pharmaceutical
Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Sreekanth Kokkonda
- Departments
of Chemistry and Global Health, University of Washington, Seattle, Washington 98195, United States
| | | | - John White
- Departments
of Chemistry and Global Health, University of Washington, Seattle, Washington 98195, United States
| | | | - Kennan Marsh
- AbbVie Inc., 1 North Waukegan
Road, North Chicago, Illinois 60064-6104, United States
| | | | | | | | - Grennady Wirjanata
- Global
and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, P.O. Box 41096, Casuarina, NT 0811, Australia
| | - Rintis Noviyanti
- Eijkman Institute for Molecular Biology, Jl. Diponegoro 69, 10430 Jakarta, Indonesia
| | - Ric N. Price
- Global
and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, P.O. Box 41096, Casuarina, NT 0811, Australia
- Centre
for Tropical Medicine and Global Health, Nuffield Department of Clinical
Medicine, University of Oxford, Oxford OX3 7LJ, U.K
| | - Jutta Marfurt
- Global
and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, P.O. Box 41096, Casuarina, NT 0811, Australia
| | - David M. Shackleford
- Centre
for Drug Candidate Optimisation, Monash Institute of Pharmaceutical
Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Francis C. K. Chiu
- Centre
for Drug Candidate Optimisation, Monash Institute of Pharmaceutical
Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Michael Campbell
- Centre
for Drug Candidate Optimisation, Monash Institute of Pharmaceutical
Sciences, Monash University, Parkville, VIC 3052, Australia
| | | | - Santiago Ferrer Bazaga
- GlaxoSmithKline, Tres Cantos Medicines Development
Campus, Severo Ochoa, Madrid 28760, Spain
| | - Iñigo Angulo-Barturen
- GlaxoSmithKline, Tres Cantos Medicines Development
Campus, Severo Ochoa, Madrid 28760, Spain
| | - Maria Santos Martinez
- GlaxoSmithKline, Tres Cantos Medicines Development
Campus, Severo Ochoa, Madrid 28760, Spain
| | | | - Werner Kaminsky
- Departments
of Chemistry and Global Health, University of Washington, Seattle, Washington 98195, United States
| | - Kigbafori Silue
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, Km17, Route de Dabou, Adiopodoumé, BP 1303 Abidjan, Ivory Coast
| | - Anne-Marie Zeeman
- Biomedical Primate Research Centre, 2288 GJ Rijswijk, The Netherlands
| | - Clemens Kocken
- Biomedical Primate Research Centre, 2288 GJ Rijswijk, The Netherlands
| | - Didier Leroy
- Medicines for Malaria Venture, 1215 Geneva, Switzerland
| | | | | | | | - Dave Matthews
- Medicines for Malaria Venture, 1215 Geneva, Switzerland
| | | | | | | | - Pradipsinh K. Rathod
- Departments
of Chemistry and Global Health, University of Washington, Seattle, Washington 98195, United States
| | - Susan A. Charman
- Centre
for Drug Candidate Optimisation, Monash Institute of Pharmaceutical
Sciences, Monash University, Parkville, VIC 3052, Australia
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87
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Williamson AE, Ylioja PM, Robertson MN, Antonova-Koch Y, Avery V, Baell JB, Batchu H, Batra S, Burrows JN, Bhattacharyya S, Calderon F, Charman SA, Clark J, Crespo B, Dean M, Debbert SL, Delves M, Dennis ASM, Deroose F, Duffy S, Fletcher S, Giaever G, Hallyburton I, Gamo FJ, Gebbia M, Guy RK, Hungerford Z, Kirk K, Lafuente-Monasterio M, Lee A, Meister S, Nislow C, Overington JP, Papadatos G, Patiny L, Pham J, Ralph S, Ruecker A, Ryan E, Southan C, Srivastava K, Swain C, Tarnowski M, Thomson P, Turner P, Wallace IM, Wells TC, White K, White L, Willis P, Winzeler EA, Wittlin S, Todd MH. Open Source Drug Discovery: Highly Potent Antimalarial Compounds Derived from the Tres Cantos Arylpyrroles. ACS CENTRAL SCIENCE 2016; 2:687-701. [PMID: 27800551 PMCID: PMC5084075 DOI: 10.1021/acscentsci.6b00086] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Indexed: 05/26/2023]
Abstract
The development of new antimalarial compounds remains a pivotal part of the strategy for malaria elimination. Recent large-scale phenotypic screens have provided a wealth of potential starting points for hit-to-lead campaigns. One such public set is explored, employing an open source research mechanism in which all data and ideas were shared in real time, anyone was able to participate, and patents were not sought. One chemical subseries was found to exhibit oral activity but contained a labile ester that could not be replaced without loss of activity, and the original hit exhibited remarkable sensitivity to minor structural change. A second subseries displayed high potency, including activity within gametocyte and liver stage assays, but at the cost of low solubility. As an open source research project, unexplored avenues are clearly identified and may be explored further by the community; new findings may be cumulatively added to the present work.
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Affiliation(s)
- Alice E. Williamson
- School
of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Paul M. Ylioja
- School
of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Murray N. Robertson
- School
of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Yevgeniya Antonova-Koch
- Department
of Pediatrics, Pharmacology & Drug Development, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Vicky Avery
- Discovery Biology, Eskitis Institute for
Drug Discovery, Griffith University, Nathan, Queensland 4111, Australia
| | - Jonathan B. Baell
- Monash
Institute of Pharmaceutical Sciences, Monash
University, 381 Royal
Parade, Parkville, Victoria 3052, Australia
| | - Harikrishna Batchu
- CSIR-Central
Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow, 226 031, India
| | - Sanjay Batra
- CSIR-Central
Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow, 226 031, India
| | - Jeremy N. Burrows
- Medicines for Malaria Venture, PO Box
1826, 20 rte de Pre-Bois, 1215 Geneva 15, Switzerland
| | - Soumya Bhattacharyya
- CSIR-Central
Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow, 226 031, India
| | - Felix Calderon
- Tres Cantos Medicines Development Campus, Diseases of the Developing
World, GlaxoSmithKline, Severo Ochoa 2, 28760 Tres Cantos, Spain
| | - Susan A. Charman
- Monash
Institute of Pharmaceutical Sciences, Monash
University, 381 Royal
Parade, Parkville, Victoria 3052, Australia
| | - Julie Clark
- Department of Chemical
Biology & Therapeutics, St. Jude Children’s
Research Hospital, MS 1000, Room E9050, 262 Danny Thomas Place, Memphis, Tennessee 38105-3678, United States
| | - Benigno Crespo
- Tres Cantos Medicines Development Campus, Diseases of the Developing
World, GlaxoSmithKline, Severo Ochoa 2, 28760 Tres Cantos, Spain
| | - Matin Dean
- School
of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Stefan L. Debbert
- Department of Chemistry, Lawrence University, 233 Steitz Science
Hall, 711 East Boldt Way, Appleton, Wisconsin 54911, United States
| | - Michael Delves
- Department of Life Sciences, Imperial College London, South Kensington, London SW7 2AZ, U.K.
| | - Adelaide S. M. Dennis
- Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia
| | - Frederik Deroose
- Asclepia Outsourcing Solutions, Damvalleistraat 49, B-9070 Destelbergen, Belgium
| | - Sandra Duffy
- Discovery Biology, Eskitis Institute for
Drug Discovery, Griffith University, Nathan, Queensland 4111, Australia
| | - Sabine Fletcher
- Discovery Biology, Eskitis Institute for
Drug Discovery, Griffith University, Nathan, Queensland 4111, Australia
| | - Guri Giaever
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Irene Hallyburton
- Drug Discovery Unit, Division of Biological
Chemistry and Drug Discovery, University
of Dundee, Dundee, DD1 5EH, U.K.
| | - Francisco-Javier Gamo
- Tres Cantos Medicines Development Campus, Diseases of the Developing
World, GlaxoSmithKline, Severo Ochoa 2, 28760 Tres Cantos, Spain
| | - Marinella Gebbia
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - R. Kiplin Guy
- Department of Chemical
Biology & Therapeutics, St. Jude Children’s
Research Hospital, MS 1000, Room E9050, 262 Danny Thomas Place, Memphis, Tennessee 38105-3678, United States
| | - Zoe Hungerford
- School
of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Kiaran Kirk
- Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia
| | - Maria
J. Lafuente-Monasterio
- Tres Cantos Medicines Development Campus, Diseases of the Developing
World, GlaxoSmithKline, Severo Ochoa 2, 28760 Tres Cantos, Spain
| | - Anna Lee
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Stephan Meister
- Department
of Pediatrics, Pharmacology & Drug Development, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Corey Nislow
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - John P. Overington
- European Molecular
Biology Laboratory—European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SD, U.K.
| | - George Papadatos
- European Molecular
Biology Laboratory—European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SD, U.K.
| | - Luc Patiny
- Institute of Chemical Sciences and Engineering
(ISIC), Ecole Polytechnique Fédérale
de Lausanne (EPFL), Lausanne 1015, Switzerland
| | - James Pham
- Department
of Biochemistry & Molecular Biology, Bio21 Molecular Science and
Biotechnology Institute, The University
of Melbourne, Melbourne, Victoria 3010, Australia
| | - Stuart
A. Ralph
- Department
of Biochemistry & Molecular Biology, Bio21 Molecular Science and
Biotechnology Institute, The University
of Melbourne, Melbourne, Victoria 3010, Australia
| | - Andrea Ruecker
- Department of Life Sciences, Imperial College London, South Kensington, London SW7 2AZ, U.K.
| | - Eileen Ryan
- Monash
Institute of Pharmaceutical Sciences, Monash
University, 381 Royal
Parade, Parkville, Victoria 3052, Australia
| | - Christopher Southan
- IUPHAR/BPS Guide to PHARMACOLOGY, Centre for Integrative Physiology,
School of Biomedical Sciences, University
of Edinburgh, Edinburgh, EH8 9XD, U.K.
| | - Kumkum Srivastava
- CSIR-Central
Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow, 226 031, India
| | - Chris Swain
- Cambridge MedChem
Consulting, 8 Mangers
Lane, Duxford, Cambridge CB22 4RN, U.K.
| | - Matthew
J. Tarnowski
- School
of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Patrick Thomson
- School
of Chemistry, The University of Edinburgh, Joseph Black Building, West Mains
Road, Edinburgh EH9 3JJ, U.K.
| | - Peter Turner
- School
of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Iain M. Wallace
- European Molecular
Biology Laboratory—European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SD, U.K.
| | - Timothy
N. C. Wells
- Medicines for Malaria Venture, PO Box
1826, 20 rte de Pre-Bois, 1215 Geneva 15, Switzerland
| | - Karen White
- Monash
Institute of Pharmaceutical Sciences, Monash
University, 381 Royal
Parade, Parkville, Victoria 3052, Australia
| | - Laura White
- School
of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Paul Willis
- Medicines for Malaria Venture, PO Box
1826, 20 rte de Pre-Bois, 1215 Geneva 15, Switzerland
| | - Elizabeth A. Winzeler
- Department
of Pediatrics, Pharmacology & Drug Development, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Sergio Wittlin
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051 Basel, Switzerland
| | - Matthew H. Todd
- School
of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
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88
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Metabolomic Profiling of the Malaria Box Reveals Antimalarial Target Pathways. Antimicrob Agents Chemother 2016; 60:6635-6649. [PMID: 27572391 DOI: 10.1128/aac.01224-16] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 08/16/2016] [Indexed: 12/11/2022] Open
Abstract
The threat of widespread drug resistance to frontline antimalarials has renewed the urgency for identifying inexpensive chemotherapeutic compounds that are effective against Plasmodium falciparum, the parasite species responsible for the greatest number of malaria-related deaths worldwide. To aid in the fight against malaria, a recent extensive screening campaign has generated thousands of lead compounds with low micromolar activity against blood stage parasites. A subset of these leads has been compiled by the Medicines for Malaria Venture (MMV) into a collection of structurally diverse compounds known as the MMV Malaria Box. Currently, little is known regarding the activity of these Malaria Box compounds on parasite metabolism during intraerythrocytic development, and a majority of the targets for these drugs have yet to be defined. Here we interrogated the in vitro metabolic effects of 189 drugs (including 169 of the drug-like compounds from the Malaria Box) using ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS). The resulting metabolic fingerprints provide information on the parasite biochemical pathways affected by pharmacologic intervention and offer a critical blueprint for selecting and advancing lead compounds as next-generation antimalarial drugs. Our results reveal several major classes of metabolic disruption, which allow us to predict the mode of action (MoA) for many of the Malaria Box compounds. We anticipate that future combination therapies will be greatly informed by these results, allowing for the selection of appropriate drug combinations that simultaneously target multiple metabolic pathways, with the aim of eliminating malaria and forestalling the expansion of drug-resistant parasites in the field.
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89
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Weiner J, Kooij TWA. Phylogenetic profiles of all membrane transport proteins of the malaria parasite highlight new drug targets. MICROBIAL CELL 2016; 3:511-521. [PMID: 28357319 PMCID: PMC5348985 DOI: 10.15698/mic2016.10.534] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In order to combat the on-going malaria epidemic, discovery of new drug targets
remains vital. Proteins that are essential to survival and specific to malaria
parasites are key candidates. To survive within host cells, the parasites need
to acquire nutrients and dispose of waste products across multiple membranes.
Additionally, like all eukaryotes, they must redistribute ions and organic
molecules between their various internal membrane bound compartments. Membrane
transport proteins mediate all of these processes and are considered important
mediators of drug resistance as well as drug targets in their own right.
Recently, using advanced experimental genetic approaches and streamlined life
cycle profiling, we generated a large collection of Plasmodium
berghei gene deletion mutants and assigned essential gene
functions, highlighting potential targets for prophylactic, therapeutic, and
transmission-blocking anti-malarial drugs. Here, we present a comprehensive
orthology assignment of all Plasmodium falciparum putative
membrane transport proteins and provide a detailed overview of the associated
essential gene functions obtained through experimental genetics studies in human
and murine model parasites. Furthermore, we discuss the phylogeny of selected
potential drug targets identified in our functional screen. We extensively
discuss the results in the context of the functional assignments obtained using
gene targeting available to date.
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Affiliation(s)
- January Weiner
- Department of Immunology, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Taco W A Kooij
- Department of Medical Microbiology & Centre for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands
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The Spiroindolone KAE609 Does Not Induce Dormant Ring Stages in Plasmodium falciparum Parasites. Antimicrob Agents Chemother 2016; 60:5167-74. [PMID: 27297484 DOI: 10.1128/aac.02838-15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 06/02/2016] [Indexed: 01/12/2023] Open
Abstract
In vitro drug treatment with artemisinin derivatives, such as dihydroartemisinin (DHA), results in a temporary growth arrest (i.e., dormancy) at an early ring stage in Plasmodium falciparum This response has been proposed to play a role in the recrudescence of P. falciparum infections following monotherapy with artesunate and may contribute to the development of artemisinin resistance in P. falciparum malaria. We demonstrate here that artemether does induce dormant rings, a finding which further supports the class effect of artemisinin derivatives in inducing the temporary growth arrest of P. falciparum parasites. In contrast and similarly to lumefantrine, the novel and fast-acting spiroindolone compound KAE609 does not induce growth arrest at the early ring stage of P. falciparum and prevents the recrudescence of DHA-arrested rings at a low concentration (50 nM). Our findings, together with previous clinical data showing that KAE609 is active against artemisinin-resistant K13 mutant parasites, suggest that KAE609 could be an effective partner drug with a broad range of antimalarials, including artemisinin derivatives, in the treatment of multidrug-resistant P. falciparum malaria.
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Open Source Drug Discovery with the Malaria Box Compound Collection for Neglected Diseases and Beyond. PLoS Pathog 2016; 12:e1005763. [PMID: 27467575 PMCID: PMC4965013 DOI: 10.1371/journal.ppat.1005763] [Citation(s) in RCA: 205] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 06/21/2016] [Indexed: 01/22/2023] Open
Abstract
A major cause of the paucity of new starting points for drug discovery is the lack of interaction between academia and industry. Much of the global resource in biology is present in universities, whereas the focus of medicinal chemistry is still largely within industry. Open source drug discovery, with sharing of information, is clearly a first step towards overcoming this gap. But the interface could especially be bridged through a scale-up of open sharing of physical compounds, which would accelerate the finding of new starting points for drug discovery. The Medicines for Malaria Venture Malaria Box is a collection of over 400 compounds representing families of structures identified in phenotypic screens of pharmaceutical and academic libraries against the Plasmodium falciparum malaria parasite. The set has now been distributed to almost 200 research groups globally in the last two years, with the only stipulation that information from the screens is deposited in the public domain. This paper reports for the first time on 236 screens that have been carried out against the Malaria Box and compares these results with 55 assays that were previously published, in a format that allows a meta-analysis of the combined dataset. The combined biochemical and cellular assays presented here suggest mechanisms of action for 135 (34%) of the compounds active in killing multiple life-cycle stages of the malaria parasite, including asexual blood, liver, gametocyte, gametes and insect ookinete stages. In addition, many compounds demonstrated activity against other pathogens, showing hits in assays with 16 protozoa, 7 helminths, 9 bacterial and mycobacterial species, the dengue fever mosquito vector, and the NCI60 human cancer cell line panel of 60 human tumor cell lines. Toxicological, pharmacokinetic and metabolic properties were collected on all the compounds, assisting in the selection of the most promising candidates for murine proof-of-concept experiments and medicinal chemistry programs. The data for all of these assays are presented and analyzed to show how outstanding leads for many indications can be selected. These results reveal the immense potential for translating the dispersed expertise in biological assays involving human pathogens into drug discovery starting points, by providing open access to new families of molecules, and emphasize how a small additional investment made to help acquire and distribute compounds, and sharing the data, can catalyze drug discovery for dozens of different indications. Another lesson is that when multiple screens from different groups are run on the same library, results can be integrated quickly to select the most valuable starting points for subsequent medicinal chemistry efforts. Malaria leads to the loss of over 440,000 lives annually; accelerating research to discover new candidate drugs is a priority. Medicines for Malaria Venture (MMV) has distilled over 25,000 compounds that kill malaria parasites in vitro into a group of 400 representative compounds, called the "Malaria Box". These Malaria Box sets were distributed free-of-charge to research laboratories in 30 different countries that work on a wide variety of pathogens. Fifty-five groups compiled >290 assay results for this paper describing the many activities of the Malaria Box compounds. The collective results suggest a potential mechanism of action for over 130 compounds against malaria and illuminate the most promising compounds for further malaria drug development research. Excitingly some of these compounds also showed outstanding activity against other disease agents including fungi, bacteria, other single-cellular parasites, worms, and even human cancer cells. The results have ignited over 30 drug development programs for a variety of diseases. This open access effort was so successful that MMV has begun to distribute another set of compounds with initial activity against a wider range of infectious agents that are of public health concern, called the Pathogen Box, available now to scientific labs all over the world (www.PathogenBox.org).
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Winterberg M, Kirk K. A high-sensitivity HPLC assay for measuring intracellular Na(+) and K(+) and its application to Plasmodium falciparum infected erythrocytes. Sci Rep 2016; 6:29241. [PMID: 27385291 PMCID: PMC4935891 DOI: 10.1038/srep29241] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 06/14/2016] [Indexed: 01/07/2023] Open
Abstract
The measurement of intracellular ion concentrations, and the screening of chemical agents to identify molecules targeting ion transport, has traditionally involved low-throughput techniques. Here we present a novel HPLC method that allows the rapid, high-sensitivity measurement of cell Na+ and K+ content, demonstrating its utility by monitoring the ionic changes induced in the intracellular malaria parasite by the new spiroindolone antimalarial KAE609.
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Affiliation(s)
- Markus Winterberg
- Research School of Biology, Australian National University, Canberra, ACT 2601, Australia.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, UK.,Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Kiaran Kirk
- Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
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93
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Abstract
Some hours after invading the erythrocytes of its human host, the malaria parasite Plasmodium falciparum induces an increase in the permeability of the erythrocyte membrane to monovalent ions. The resulting net influx of Na(+) and net efflux of K(+), down their respective concentration gradients, converts the erythrocyte cytosol from an initially high-K(+), low-Na(+) solution to a high-Na(+), low-K(+) solution. The intraerythrocytic parasite itself exerts tight control over its internal Na(+), K(+), Cl(-), and Ca(2+) concentrations and its intracellular pH through the combined actions of a range of membrane transport proteins. The molecular mechanisms underpinning ion regulation in the parasite are receiving increasing attention, not least because PfATP4, a P-type ATPase postulated to be involved in Na(+) regulation, has emerged as a potential antimalarial drug target, susceptible to inhibition by a wide range of chemically unrelated compounds.
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Affiliation(s)
- Kiaran Kirk
- Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia;
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94
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Abstract
Intracellular single-celled parasites belonging to the large phylum Apicomplexa are amongst the most prevalent and morbidity-causing pathogens worldwide. In this review, we highlight a few of the many recent advances in the field that helped to clarify some important aspects of their fascinating biology and interaction with their hosts.
Plasmodium falciparum causes malaria, and thus the recent emergence of resistance against the currently used drug combinations based on artemisinin has been of major interest for the scientific community. It resulted in great advances in understanding the resistance mechanisms that can hopefully be translated into altered future drug regimens. Apicomplexa are also experts in host cell manipulation and immune evasion.
Toxoplasma gondii and
Theileria sp., besides
Plasmodium sp., are species that secrete effector molecules into the host cell to reach this aim. The underlying molecular mechanisms for how these proteins are trafficked to the host cytosol (
T. gondii and
Plasmodium) and how a secreted protein can immortalize the host cell (
Theileria sp.) have been illuminated recently. Moreover, how such secreted proteins affect the host innate immune responses against
T. gondii and the liver stages of
Plasmodium has also been unraveled at the genetic and molecular level, leading to unexpected insights. Methodological advances in metabolomics and molecular biology have been instrumental to solving some fundamental puzzles of mitochondrial carbon metabolism in Apicomplexa. Also, for the first time, the generation of stably transfected
Cryptosporidium parasites was achieved, which opens up a wide variety of experimental possibilities for this understudied, important apicomplexan pathogen.
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Affiliation(s)
- Frank Seeber
- FG16: Mycotic and parasitic agents and mycobacteria, Robert Koch-Institute, Berlin, Germany
| | - Svenja Steinfelder
- Institute of Immunology, Center of Infection Medicine, Free University Berlin, Berlin, Germany
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Goldgof GM, Durrant JD, Ottilie S, Vigil E, Allen KE, Gunawan F, Kostylev M, Henderson KA, Yang J, Schenken J, LaMonte GM, Manary MJ, Murao A, Nachon M, Murray R, Prescott M, McNamara CW, Slayman CW, Amaro RE, Suzuki Y, Winzeler EA. Comparative chemical genomics reveal that the spiroindolone antimalarial KAE609 (Cipargamin) is a P-type ATPase inhibitor. Sci Rep 2016; 6:27806. [PMID: 27291296 PMCID: PMC4904242 DOI: 10.1038/srep27806] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 05/20/2016] [Indexed: 11/30/2022] Open
Abstract
The spiroindolones, a new class of antimalarial medicines discovered in a cellular screen, are rendered less active by mutations in a parasite P-type ATPase, PfATP4. We show here that S. cerevisiae also acquires mutations in a gene encoding a P-type ATPase (ScPMA1) after exposure to spiroindolones and that these mutations are sufficient for resistance. KAE609 resistance mutations in ScPMA1 do not confer resistance to unrelated antimicrobials, but do confer cross sensitivity to the alkyl-lysophospholipid edelfosine, which is known to displace ScPma1p from the plasma membrane. Using an in vitro cell-free assay, we demonstrate that KAE609 directly inhibits ScPma1p ATPase activity. KAE609 also increases cytoplasmic hydrogen ion concentrations in yeast cells. Computer docking into a ScPma1p homology model identifies a binding mode that supports genetic resistance determinants and in vitro experimental structure-activity relationships in both P. falciparum and S. cerevisiae. This model also suggests a shared binding site with the dihydroisoquinolones antimalarials. Our data support a model in which KAE609 exerts its antimalarial activity by directly interfering with P-type ATPase activity.
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Affiliation(s)
- Gregory M. Goldgof
- Division of Pharmacology and Drug Discovery, Department of
Pediatrics, University of California, San Diego, School of Medicine,
La Jolla, California, USA
- Department of Synthetic Biology and Bioenergy, J. Craig Venter
Institute, La Jolla, California, USA
| | - Jacob D. Durrant
- Department of Chemistry & Biochemistry and the National
Biomedical Computation Resource, University of California, San
Diego, La Jolla, California, USA
| | - Sabine Ottilie
- Division of Pharmacology and Drug Discovery, Department of
Pediatrics, University of California, San Diego, School of Medicine,
La Jolla, California, USA
| | - Edgar Vigil
- Division of Pharmacology and Drug Discovery, Department of
Pediatrics, University of California, San Diego, School of Medicine,
La Jolla, California, USA
| | - Kenneth E. Allen
- Department of Genetics, Yale University School of
Medicine, New Haven, Connecticut, USA
| | - Felicia Gunawan
- Division of Pharmacology and Drug Discovery, Department of
Pediatrics, University of California, San Diego, School of Medicine,
La Jolla, California, USA
| | - Maxim Kostylev
- Department of Synthetic Biology and Bioenergy, J. Craig Venter
Institute, La Jolla, California, USA
| | | | - Jennifer Yang
- Division of Pharmacology and Drug Discovery, Department of
Pediatrics, University of California, San Diego, School of Medicine,
La Jolla, California, USA
| | - Jake Schenken
- Division of Pharmacology and Drug Discovery, Department of
Pediatrics, University of California, San Diego, School of Medicine,
La Jolla, California, USA
| | - Gregory M. LaMonte
- Division of Pharmacology and Drug Discovery, Department of
Pediatrics, University of California, San Diego, School of Medicine,
La Jolla, California, USA
| | - Micah J. Manary
- Division of Pharmacology and Drug Discovery, Department of
Pediatrics, University of California, San Diego, School of Medicine,
La Jolla, California, USA
| | - Ayako Murao
- Department of Synthetic Biology and Bioenergy, J. Craig Venter
Institute, La Jolla, California, USA
| | - Marie Nachon
- Division of Pharmacology and Drug Discovery, Department of
Pediatrics, University of California, San Diego, School of Medicine,
La Jolla, California, USA
| | - Rebecca Murray
- Division of Pharmacology and Drug Discovery, Department of
Pediatrics, University of California, San Diego, School of Medicine,
La Jolla, California, USA
| | - Maximo Prescott
- Division of Pharmacology and Drug Discovery, Department of
Pediatrics, University of California, San Diego, School of Medicine,
La Jolla, California, USA
| | - Case W. McNamara
- Genomics Institute of the Novartis Research Foundation,
San Diego, California, USA
| | - Carolyn W. Slayman
- Department of Genetics, Yale University School of
Medicine, New Haven, Connecticut, USA
| | - Rommie E. Amaro
- Department of Chemistry & Biochemistry and the National
Biomedical Computation Resource, University of California, San
Diego, La Jolla, California, USA
| | - Yo Suzuki
- Department of Synthetic Biology and Bioenergy, J. Craig Venter
Institute, La Jolla, California, USA
| | - Elizabeth A. Winzeler
- Division of Pharmacology and Drug Discovery, Department of
Pediatrics, University of California, San Diego, School of Medicine,
La Jolla, California, USA
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Na+ Influx Induced by New Antimalarials Causes Rapid Alterations in the Cholesterol Content and Morphology of Plasmodium falciparum. PLoS Pathog 2016; 12:e1005647. [PMID: 27227970 PMCID: PMC4881962 DOI: 10.1371/journal.ppat.1005647] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 04/28/2016] [Indexed: 12/27/2022] Open
Abstract
Among the several new antimalarials discovered over the past decade are at least three clinical candidate drugs, each with a distinct chemical structure, that disrupt Na+ homeostasis resulting in a rapid increase in intracellular Na+ concentration ([Na+]i) within the erythrocytic stages of Plasmodium falciparum. At present, events triggered by Na+ influx that result in parasite demise are not well-understood. Here we report effects of two such drugs, a pyrazoleamide and a spiroindolone, on intraerythrocytic P. falciparum. Within minutes following the exposure to these drugs, the trophozoite stage parasite, which normally contains little cholesterol, was made permeant by cholesterol-dependent detergents, suggesting it acquired a substantial amount of the lipid. Consistently, the merozoite surface protein 1 and 2 (MSP1 and MSP2), glycosylphosphotidylinositol (GPI)-anchored proteins normally uniformly distributed in the parasite plasma membrane, coalesced into clusters. These alterations were not observed following drug treatment of P. falciparum parasites adapted to grow in a low [Na+] growth medium. Both cholesterol acquisition and MSP1 coalescence were reversible upon the removal of the drugs, implicating an active process of cholesterol exclusion from trophozoites that we hypothesize is inhibited by high [Na+]i. Electron microscopy of drug-treated trophozoites revealed substantial morphological changes normally seen at the later schizont stage including the appearance of partial inner membrane complexes, dense organelles that resemble "rhoptries" and apparent nuclear division. Together these results suggest that [Na+]i disruptor drugs by altering levels of cholesterol in the parasite, dysregulate trophozoite to schizont development and cause parasite demise.
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Reappraising the effects of artemisinin on the ATPase activity of PfATP6 and SERCA1a E255L expressed in Xenopus laevis oocytes. Nat Struct Mol Biol 2016; 23:1-2. [PMID: 26733217 DOI: 10.1038/nsmb.3156] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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98
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Skinner-Adams TS, Sumanadasa SD, Fisher GM, Davis RA, Doolan DL, Andrews KT. Defining the targets of antiparasitic compounds. Drug Discov Today 2016; 21:725-39. [DOI: 10.1016/j.drudis.2016.01.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 12/04/2015] [Accepted: 01/07/2016] [Indexed: 10/22/2022]
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99
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Lee AH, Fidock DA. Evidence of a Mild Mutator Phenotype in Cambodian Plasmodium falciparum Malaria Parasites. PLoS One 2016; 11:e0154166. [PMID: 27100094 PMCID: PMC4839739 DOI: 10.1371/journal.pone.0154166] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Accepted: 04/09/2016] [Indexed: 12/22/2022] Open
Abstract
Malaria control efforts have been continuously stymied by drug-resistant strains of Plasmodium falciparum, which typically originate in Southeast Asia prior to spreading into high-transmission settings in Africa. One earlier proposed explanation for Southeast Asia being a hotbed of resistance has been the hypermutability or "Accelerated Resistance to Multiple Drugs" (ARMD) phenotype, whereby multidrug-resistant Southeast Asian parasites were reported to exhibit 1,000-fold higher rates of resistance to unrelated antimalarial agents when compared to drug-sensitive parasites. However, three recent studies do not recapitulate this hypermutability phenotype. Intriguingly, genome sequencing of recently derived multidrug-resistant Cambodian isolates has identified a high proportion of DNA repair gene mutations in multidrug-resistant parasites, suggesting their potential role in shaping local parasite evolution. By adapting fluctuation assays for use in P. falciparum, we have examined the in vitro mutation rates of five recent Cambodian isolates and three reference laboratory strains. For these studies we also generated a knockout parasite line lacking the DNA repair factor Exonuclease I. In these assays, parasites were typed for their ability to acquire resistance to KAE609, currently in advanced clinical trials, yielding 13 novel mutations in the Na+/H+-ATPase PfATP4, the primary resistance determinant. We observed no evidence of hypermutability. Instead, we found evidence of a mild mutator (up to a 3.4-fold increase in mutation rate) phenotype in two artemisinin-resistant Cambodian isolates, which carry DNA repair gene mutations. We observed that one such mutation in the Mismatch Repair protein Mlh1 contributes to the mild mutator phenotype when modeled in yeast (scmlh1-P157S). Compared to basal rates of mutation, a mild mutator phenotype may provide a greater overall benefit for parasites in Southeast Asia in terms of generating drug resistance without incurring detrimental fitness costs.
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Affiliation(s)
- Andrew H. Lee
- Department of Microbiology and Immunology, Columbia University, New York, New York, United States of America
| | - David A. Fidock
- Department of Microbiology and Immunology, Columbia University, New York, New York, United States of America
- Division of Infectious Diseases, Department of Medicine, Columbia University, New York, New York, United States of America
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Abstract
INTRODUCTION Antimalarial drugs are the primary weapon to treat parasite infection, save lives, and curtail further transmission. Accumulating data have indicated that at least some antimalarial drugs may contribute to severe neurological and/or psychiatric side effects which further complicates their use and limits the pool of available medications. AREAS COVERED In this review article, we summarize published scientific studies in search of evidence of the neuropsychiatric effects that may be attributed to the commonly used antimalarial drugs administered alone or in combination. Each individual drug was used as a search term in addition to keywords such as neuropsychiatric, adverse events, and neurotoxicity. EXPERT OPINION Accumulating data based on published reports over several decades have suggested that among the major commonly used antimalarial drugs, only mefloquine exhibited clear indications of serious neurological and/or psychiatric side effects. A more systematic approach to assess the neuropsychiatric adverse effects of new or repurposed antimalarial drugs on their safety, tolerability and efficacy phases of clinical studies and in post-marketing surveillance, is needed to ensure that these life-saving tools remain available and can be prescribed with appropriate caution and medical judgment.
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Affiliation(s)
- Bryan Grabias
- a Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases , Center for Biologics Evaluation and Research, Food and Drug Administration , Silver Spring , MD , USA
| | - Sanjai Kumar
- a Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases , Center for Biologics Evaluation and Research, Food and Drug Administration , Silver Spring , MD , USA
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