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Cheuka PM, Njaria P, Mayoka G, Funjika E. Emerging Drug Targets for Antimalarial Drug Discovery: Validation and Insights into Molecular Mechanisms of Function. J Med Chem 2024; 67:838-863. [PMID: 38198596 DOI: 10.1021/acs.jmedchem.3c01828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2024]
Abstract
Approximately 619,000 malaria deaths were reported in 2021, and resistance to recommended drugs, including artemisinin-combination therapies (ACTs), threatens malaria control. Treatment failure with ACTs has been found to be as high as 93% in northeastern Thailand, and parasite mutations responsible for artemisinin resistance have already been reported in some African countries. Therefore, there is an urgent need to identify alternative treatments with novel targets. In this Perspective, we discuss some promising antimalarial drug targets, including enzymes involved in proteolysis, DNA and RNA metabolism, protein synthesis, and isoprenoid metabolism. Other targets discussed are transporters, Plasmodium falciparum acetyl-coenzyme A synthetase, N-myristoyltransferase, and the cyclic guanosine monophosphate-dependent protein kinase G. We have outlined mechanistic details, where these are understood, underpinning the biological roles and hence druggability of such targets. We believe that having a clear understanding of the underlying chemical interactions is valuable to medicinal chemists in their quest to design appropriate inhibitors.
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Affiliation(s)
- Peter Mubanga Cheuka
- Department of Chemistry, School of Natural Sciences, University of Zambia, P.O. Box 32379, Lusaka 10101, Zambia
| | - Paul Njaria
- Department of Pharmacognosy and Pharmaceutical Chemistry, Kenyatta University, P.O. Box 14548-00400, Nairobi 00100, Kenya
| | - Godfrey Mayoka
- Department of Pharmacology and Pharmacognosy, School of Pharmacy, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Nairobi 00100, Kenya
| | - Evelyn Funjika
- Department of Chemistry, School of Natural Sciences, University of Zambia, P.O. Box 32379, Lusaka 10101, Zambia
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2
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Dillague C, Akabas MH. Putative purine nucleoside interacting residues in the malaria parasite purine uptake transporter PfENT1 are critical for transporter function. PLoS One 2023; 18:e0293923. [PMID: 38113238 PMCID: PMC10729961 DOI: 10.1371/journal.pone.0293923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 10/22/2023] [Indexed: 12/21/2023] Open
Abstract
Malaria remains a major public health threat for billions of people worldwide. Infection with obligate intracellular, unicellular parasites from the genus Plasmodium causes malaria. Plasmodium falciparum causes the deadliest form of human malaria. Plasmodium parasites are purine auxotrophic. They rely on purine import from the host red blood cell cytoplasm via equilibrative nucleoside transporters to supply substrates to the purine salvage pathway. We previously developed a high throughput screening assay to identify inhibitors of the P. falciparum Equilibrative Nucleoside Transporter Type 1 (PfENT1). Screening a small molecule library identified PfENT1 inhibitors that blocked proliferation of P. falciparum parasites in in vitro culture. The goal of the current work was to validate a high-resolution model of PfENT1 predicted by the AlphaFold protein structure prediction program. We superimposed the predicted PfENT1 structure on the human homologue structure, hENT1, and developed a structure-based sequence alignment. We mutated the residues in PfENT1 aligned with and flanking the residues in hENT1 that interact with the purine analog, nitrobenzylthioinosine (NBMPR). Mutation of the PfENT1 residues Q135, D287, and R291 that are predicted to form hydrogen bonds to purine nucleosides eliminated purine and pyrimidine transport function in various yeast-based growth and radiolabeled substrate uptake assays. Mutation of two flanking residues, W53 and S290, also resulted in inactive protein. Mutation of L50 that forms hydrophobic interactions with the purine nucleobase reduced transport function. Based on our results the AlphaFold predicted structure for PfENT1 may be useful in guiding medicinal chemistry efforts to improve the potency of our PfENT1 inhibitors.
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Affiliation(s)
- Criselda Dillague
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Myles H. Akabas
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, United States of America
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3
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Ghosh S, Kundu R, Chandana M, Das R, Anand A, Beura S, Bobde RC, Jain V, Prabhu SR, Behera PK, Mohanty AK, Chakrapani M, Satyamoorthy K, Suryawanshi AR, Dixit A, Padmanaban G, Nagaraj VA. Distinct evolution of type I glutamine synthetase in Plasmodium and its species-specific requirement. Nat Commun 2023; 14:4216. [PMID: 37452051 PMCID: PMC10349072 DOI: 10.1038/s41467-023-39670-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 06/22/2023] [Indexed: 07/18/2023] Open
Abstract
Malaria parasite lacks canonical pathways for amino acid biosynthesis and depends primarily on hemoglobin degradation and extracellular resources for amino acids. Interestingly, a putative gene for glutamine synthetase (GS) is retained despite glutamine being an abundant amino acid in human and mosquito hosts. Here we show Plasmodium GS has evolved as a unique type I enzyme with distinct structural and regulatory properties to adapt to the asexual niche. Methionine sulfoximine (MSO) and phosphinothricin (PPT) inhibit parasite GS activity. GS is localized to the parasite cytosol and abundantly expressed in all the life cycle stages. Parasite GS displays species-specific requirement in Plasmodium falciparum (Pf) having asparagine-rich proteome. Targeting PfGS affects asparagine levels and inhibits protein synthesis through eIF2α phosphorylation leading to parasite death. Exposure of artemisinin-resistant Pf parasites to MSO and PPT inhibits the emergence of viable parasites upon artemisinin treatment.
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Affiliation(s)
- Sourav Ghosh
- Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, Odisha, India
- Regional Centre for Biotechnology, Faridabad, 121001, Haryana, India
| | - Rajib Kundu
- Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, Odisha, India
- Regional Centre for Biotechnology, Faridabad, 121001, Haryana, India
| | - Manjunatha Chandana
- Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, Odisha, India
- School of Biotechnology, Kalinga Institute of Industrial Technology, Bhubaneswar, 751024, Odisha, India
| | - Rahul Das
- Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, Odisha, India
- Regional Centre for Biotechnology, Faridabad, 121001, Haryana, India
| | - Aditya Anand
- Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, Odisha, India
- Regional Centre for Biotechnology, Faridabad, 121001, Haryana, India
| | - Subhashree Beura
- Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, Odisha, India
| | - Ruchir Chandrakant Bobde
- Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, Odisha, India
- Regional Centre for Biotechnology, Faridabad, 121001, Haryana, India
| | - Vishal Jain
- Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, Odisha, India
| | - Sowmya Ramakant Prabhu
- Department of Biotechnology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India
| | | | - Akshaya Kumar Mohanty
- Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, Odisha, India
- Ispat General Hospital, Sector 19, Rourkela, 769005, Odisha, India
| | - Mahabala Chakrapani
- Department of Medicine, Kasturba Medical College, Mangalore, Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India
| | - Kapaettu Satyamoorthy
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India
| | | | - Anshuman Dixit
- Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, Odisha, India
| | - Govindarajan Padmanaban
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, Karnataka, India
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4
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Wang C, Yu L, Zhang J, Zhou Y, Sun B, Xiao Q, Zhang M, Liu H, Li J, Li J, Luo Y, Xu J, Lian Z, Lin J, Wang X, Zhang P, Guo L, Ren R, Deng D. Structural basis of the substrate recognition and inhibition mechanism of Plasmodium falciparum nucleoside transporter PfENT1. Nat Commun 2023; 14:1727. [PMID: 36977719 PMCID: PMC10050424 DOI: 10.1038/s41467-023-37411-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 03/16/2023] [Indexed: 03/30/2023] Open
Abstract
By lacking de novo purine biosynthesis enzymes, Plasmodium falciparum requires purine nucleoside uptake from host cells. The indispensable nucleoside transporter ENT1 of P. falciparum facilitates nucleoside uptake in the asexual blood stage. Specific inhibitors of PfENT1 prevent the proliferation of P. falciparum at submicromolar concentrations. However, the substrate recognition and inhibitory mechanism of PfENT1 are still elusive. Here, we report cryo-EM structures of PfENT1 in apo, inosine-bound, and inhibitor-bound states. Together with in vitro binding and uptake assays, we identify that inosine is the primary substrate of PfENT1 and that the inosine-binding site is located in the central cavity of PfENT1. The endofacial inhibitor GSK4 occupies the orthosteric site of PfENT1 and explores the allosteric site to block the conformational change of PfENT1. Furthermore, we propose a general "rocker switch" alternating access cycle for ENT transporters. Understanding the substrate recognition and inhibitory mechanisms of PfENT1 will greatly facilitate future efforts in the rational design of antimalarial drugs.
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Affiliation(s)
- Chen Wang
- Department of Obstetrics, Key Laboratory of Birth Defects and Related Disease of Women and Children of MOE, State Key Laboratory of Biotherapy, West China Second Hospital, Sichuan University, Chengdu, 610041, China
- Shanghai Key Laboratory of Metabolic Remodeling and Health, Institute of Metabolism and Integrative Biology, Fudan University, Shanghai, 200438, China
| | - Leiye Yu
- Shanghai Key Laboratory of Metabolic Remodeling and Health, Institute of Metabolism and Integrative Biology, Fudan University, Shanghai, 200438, China
- Warshal Institute of Computational Biology, School of Life and Health Sciences, the Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
| | - Jiying Zhang
- Department of Obstetrics, Key Laboratory of Birth Defects and Related Disease of Women and Children of MOE, State Key Laboratory of Biotherapy, West China Second Hospital, Sichuan University, Chengdu, 610041, China
| | - Yanxia Zhou
- Department of Obstetrics, Key Laboratory of Birth Defects and Related Disease of Women and Children of MOE, State Key Laboratory of Biotherapy, West China Second Hospital, Sichuan University, Chengdu, 610041, China
| | - Bo Sun
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, 201204, China
| | - Qingjie Xiao
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, 201204, China
| | - Minhua Zhang
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Huayi Liu
- Department of Obstetrics, Key Laboratory of Birth Defects and Related Disease of Women and Children of MOE, State Key Laboratory of Biotherapy, West China Second Hospital, Sichuan University, Chengdu, 610041, China
| | - Jinhong Li
- Department of Obstetrics, Key Laboratory of Birth Defects and Related Disease of Women and Children of MOE, State Key Laboratory of Biotherapy, West China Second Hospital, Sichuan University, Chengdu, 610041, China
| | - Jialu Li
- Department of Obstetrics, Key Laboratory of Birth Defects and Related Disease of Women and Children of MOE, State Key Laboratory of Biotherapy, West China Second Hospital, Sichuan University, Chengdu, 610041, China
| | - Yunzi Luo
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering of MOE, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Jie Xu
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Zhong Lian
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Jingwen Lin
- Department of Obstetrics, Key Laboratory of Birth Defects and Related Disease of Women and Children of MOE, State Key Laboratory of Biotherapy, West China Second Hospital, Sichuan University, Chengdu, 610041, China
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Xiang Wang
- Department of Obstetrics, Key Laboratory of Birth Defects and Related Disease of Women and Children of MOE, State Key Laboratory of Biotherapy, West China Second Hospital, Sichuan University, Chengdu, 610041, China
| | - Peng Zhang
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Li Guo
- Department of Obstetrics, Key Laboratory of Birth Defects and Related Disease of Women and Children of MOE, State Key Laboratory of Biotherapy, West China Second Hospital, Sichuan University, Chengdu, 610041, China.
| | - Ruobing Ren
- Shanghai Key Laboratory of Metabolic Remodeling and Health, Institute of Metabolism and Integrative Biology, Fudan University, Shanghai, 200438, China.
- Shanghai Qi Zhi Institute, Shanghai, 200030, China.
| | - Dong Deng
- Department of Obstetrics, Key Laboratory of Birth Defects and Related Disease of Women and Children of MOE, State Key Laboratory of Biotherapy, West China Second Hospital, Sichuan University, Chengdu, 610041, China.
- NHC key Laboratory of Chronobiology, Sichuan University, Chengdu, 610041, China.
- Development and Related Diseases of Women and Children Key Laboratory of Sichuan Province, Sichuan University, Chengdu, 610041, China.
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5
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A single dose of genetically-attenuated malaria blood-stage parasites protects against two Plasmodium species infections. Vaccine 2023; 41:1281-1285. [PMID: 36653222 DOI: 10.1016/j.vaccine.2023.01.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 10/31/2022] [Accepted: 01/03/2023] [Indexed: 01/18/2023]
Abstract
Genetically-growth-attenuated blood-stage parasites were generated inPlasmodium falciparumby targeted deletion of NT1 (Nucleoside Transporter-1) gene, and Pfnt1(-) parasites only grew after providing the culture with supra-physiological concentrations of purines. Genetically-attenuatedP. yoeliint1(-)parasites induced sterile-protection against homologous blood-stage infectious challenge after immunization with single subpatent doses, which remained subpatent even in immune-compromised mice. Here, we showed that immunizations with frozen-stocks of equally-mixedP. bergheiandP. yoelii nt1(-)parasites in single subcutaneous doses, which did not lead to patent blood-stage infection, conferred sterile protection against intravenous infectious blood-stage challenge with wild-type parasites ofP. bergheiANKA andP. yoelii17X-NL strains. This data highlights the possibility that a single subcutaneous sub-patent dose of two species of genetically-growth-attenuated parasites, which can protect humans against twoPlasmodiumspp. infections, could be developed in cultures provided with supra-physiological concentrations of purines, and shipped to endemic areas as frozen-stock doses.
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6
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Babai R, Izrael R, Vértessy BG. Characterization of the dynamics of Plasmodium falciparum deoxynucleotide-triphosphate pool in a stage-specific manner. Sci Rep 2022; 12:19926. [PMID: 36402851 PMCID: PMC9675800 DOI: 10.1038/s41598-022-23807-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 11/06/2022] [Indexed: 11/21/2022] Open
Abstract
Understanding and characterizing the molecular background of the maintenance of genomic integrity might be a major factor in comprehending the exceptional ability of the malaria parasite, Plasmodium falciparum to adapt at a fast pace to antimalarials. A balanced nucleotide pool is an essential factor for high-fidelity replication. The lack of detailed studies on deoxynucleotide-triphosphate (dNTP) pools in various intraerythrocytic stages of Plasmodium falciparum motivated our present study. Here, we focused on the building blocks of DNA and utilized an EvaGreen-based dNTP incorporation assay to successfully measure the temporal dynamics of dNTPs in every intraerythrocytic stage and in drug-treated trophozoites. Our findings show that the ratio of dNTPs in the ring-stage parasites significantly differs from the more mature trophozoite and schizont stages. We were also able to detect dGTP levels that have never been shown before and found it to be the least abundant dNTP in all stages. Treatment with WR99210, a TS-DHFR inhibitor drug, affected not only dTTP, but also dGTP levels, despite its presumed selective action on pyrimidine biosynthesis. Results from our studies might assist in a better understanding of genome integrity mechanisms and may potentially lead to novel drug related aspects involving purine and pyrimidine metabolic targets.
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Affiliation(s)
- Réka Babai
- grid.425578.90000 0004 0512 3755Malaria Research Laboratory, Institute of Enzymology, Research Centre for Natural Sciences, Budapest, 1117 Hungary ,grid.6759.d0000 0001 2180 0451George A. Olah Doctoral School of Chemistry and Chemical Technology, BME Budapest University of Technology and Economics, Budapest, 1111 Hungary ,grid.6759.d0000 0001 2180 0451Department of Applied Biotechnology and Food Sciences, BME Budapest University of Technology and Economics, Budapest, 1111 Hungary
| | - Richard Izrael
- grid.425578.90000 0004 0512 3755Malaria Research Laboratory, Institute of Enzymology, Research Centre for Natural Sciences, Budapest, 1117 Hungary ,grid.9008.10000 0001 1016 9625Doctoral School of Multidisciplinary Medical Sciences, University of Szeged, Szeged, 6720 Hungary
| | - Beáta G. Vértessy
- grid.425578.90000 0004 0512 3755Malaria Research Laboratory, Institute of Enzymology, Research Centre for Natural Sciences, Budapest, 1117 Hungary ,grid.6759.d0000 0001 2180 0451Department of Applied Biotechnology and Food Sciences, BME Budapest University of Technology and Economics, Budapest, 1111 Hungary
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7
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Mrozek A, Antoshchenko T, Chen Y, Zepeda-Velázquez C, Smil D, Kumar N, Lu H, Park HW. A non-traditional crystal-based compound screening method targeting the ATP binding site of Plasmodium falciparum GRP78 for identification of novel nucleoside analogues. Front Mol Biosci 2022; 9:956095. [PMID: 36275624 PMCID: PMC9585173 DOI: 10.3389/fmolb.2022.956095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Accepted: 08/03/2022] [Indexed: 12/02/2022] Open
Abstract
Drug resistance to front-line malarial treatments represents an ongoing threat to control malaria, a vector borne infectious disease. The malarial parasite, Plasmodium falciparum has developed genetic variants, conferring resistance to the current standard therapeutic artemisinin and its derivatives commonly referred to as artemisinin-combination therapies (ACTs). Emergence of multi-drug resistance parasite genotypes is a warning of potential treatment failure, reaffirming the urgent and critical need to find and validate alternate drug targets to prevent the spread of disease. An attractive and novel drug target includes glucose-regulated protein 78 kDa (GRP78, or BiP), an essential molecular chaperone protein involved in the unfolded protein response that is upregulated in ACT treated P. falciparum parasites. We have shown that both sequence and structure are closely related to human GRP78 (hGRP78), a chaperone belonging to the HSP70 class of ATPase proteins, which is often upregulated in cellular stress responses and cancer. By screening a library of nucleoside analogues, we identified eight ‘hit’ compounds binding at the active site of the ATP binding domain of P. falciparum GRP78 using a high-throughput ligand soaking screen using x-ray crystallography. These compounds were further evaluated using protein thermal shift assays to assess target binding activity. The nucleoside analogues identified from our screen provide a starting point for the development of more potent and selective antimalarial inhibitors. In addition, we have established a well-defined, high-throughput crystal-based screening approach that can be applied to many crystallizable P. falciparum proteins for generating anti-Plasmodium specific compounds.
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Affiliation(s)
- Alexander Mrozek
- Department of Biochemistry & Molecular Biology, Tulane University School of Medicine, New Orleans, LA, United States
| | - Tetyana Antoshchenko
- Department of Biochemistry & Molecular Biology, Tulane University School of Medicine, New Orleans, LA, United States
| | - Yun Chen
- Department of Biochemistry & Molecular Biology, Tulane University School of Medicine, New Orleans, LA, United States
| | | | - David Smil
- Drug Discovery Program, Ontario Institute for Cancer Research, Toronto, ON, Canada
| | - Nirbhay Kumar
- Department of Global Health, George Washington University Milken Institute of Public Health, Washington, D.C., DC, United States
| | - Hua Lu
- Department of Biochemistry & Molecular Biology, Tulane University School of Medicine, New Orleans, LA, United States
| | - Hee-Won Park
- Department of Biochemistry & Molecular Biology, Tulane University School of Medicine, New Orleans, LA, United States
- *Correspondence: Hee-Won Park,
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8
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An Uninvited Seat at the Dinner Table: How Apicomplexan Parasites Scavenge Nutrients from the Host. Microorganisms 2021; 9:microorganisms9122592. [PMID: 34946193 PMCID: PMC8707601 DOI: 10.3390/microorganisms9122592] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/10/2021] [Accepted: 12/13/2021] [Indexed: 12/24/2022] Open
Abstract
Obligate intracellular parasites have evolved a remarkable assortment of strategies to scavenge nutrients from the host cells they parasitize. Most apicomplexans form a parasitophorous vacuole (PV) within the invaded cell, a replicative niche within which they survive and multiply. As well as providing a physical barrier against host cell defense mechanisms, the PV membrane (PVM) is also an important site of nutrient uptake that is essential for the parasites to sustain their metabolism. This means nutrients in the extracellular milieu are separated from parasite metabolic machinery by three different membranes, the host plasma membrane, the PVM, and the parasite plasma membrane (PPM). In order to facilitate nutrient transport from the extracellular environment into the parasite itself, transporters on the host cell membrane of invaded cells can be modified by secreted and exported parasite proteins to maximize uptake of key substrates to meet their metabolic demand. To overcome the second barrier, the PVM, apicomplexan parasites secrete proteins contained in the dense granules that remodel the vacuole and make the membrane permissive to important nutrients. This bulk flow of host nutrients is followed by a more selective uptake of substrates at the PPM that is operated by specific transporters of this third barrier. In this review, we recapitulate and compare the strategies developed by Apicomplexa to scavenge nutrients from their hosts, with particular emphasis on transporters at the parasite plasma membrane and vacuolar solute transporters on the parasite intracellular digestive organelle.
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Kurian J, Kumari V, Chaluvalappil SV, Anas M, Manhas A, Kalluruttimmal R, Kumar N, Manheri MK. Adenine Modification at C7 as a Viable Strategy to Potentiate the Antimalarial Activity of Quinolones. ChemMedChem 2021; 17:e202100472. [PMID: 34717044 DOI: 10.1002/cmdc.202100472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 10/15/2021] [Indexed: 11/08/2022]
Abstract
Although many quinolones have shown promise as potent antimalarials, their clinical development has been slow due to poor performance in vivo. Insights into structural modifications that can improve their therapeutic potential will be very valuable in this vibrant area of research. Our studies involving a library of quinolones which vary in substitution pattern at N1, C3, C6 and C7 positions have shown that the presence of adenine moiety at C7 can bring a noticeable improvement in activity compared to other heterocyclic groups at this location. The most potent compound emerged from this study showed IC50 values of 0.38 μM and 0.75 μM against chloroquine-sensitive and -resistant (W2) strains, respectively. Docking analysis in the Qo site of cytochrome bc1 complex revealed the contribution of a key H-bonding interaction from the adenine unit in target binding. This corroborates with compound-induced loss of mitochondrial functions. These findings not only open avenues for further exploration of antimalarial potential of adenine-modified quinolones, but also suggests broader opportunities during lead-optimization against other antimalarial targets.
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Affiliation(s)
- Jais Kurian
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu, India
| | - Varsha Kumari
- Department of Molecular Microbiology and Immunology, CSIR-Central Drug Research Institute, Sector 10, Jankipuram extension, Sitapur road, Lucknow, 226031, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Saheer V Chaluvalappil
- Department of Chemistry, Krishna Menon Memorial Government Women's College, Kannur 670004, Kerala, India
| | - Mohammad Anas
- Department of Molecular Microbiology and Immunology, CSIR-Central Drug Research Institute, Sector 10, Jankipuram extension, Sitapur road, Lucknow, 226031, India
| | - Ashan Manhas
- Department of Molecular Microbiology and Immunology, CSIR-Central Drug Research Institute, Sector 10, Jankipuram extension, Sitapur road, Lucknow, 226031, India
| | - Ramshad Kalluruttimmal
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu, India
| | - Niti Kumar
- Department of Molecular Microbiology and Immunology, CSIR-Central Drug Research Institute, Sector 10, Jankipuram extension, Sitapur road, Lucknow, 226031, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Muraleedharan K Manheri
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu, India
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10
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Campagnaro GD, de Koning HP. Purine and pyrimidine transporters of pathogenic protozoa - conduits for therapeutic agents. Med Res Rev 2020; 40:1679-1714. [PMID: 32144812 DOI: 10.1002/med.21667] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 02/12/2020] [Accepted: 02/18/2020] [Indexed: 02/06/2023]
Abstract
Purines and pyrimidines are essential nutrients for any cell. Most organisms are able to synthesize their own purines and pyrimidines, but this ability was lost in protozoans that adapted to parasitism, leading to a great diversification in transporter activities in these organisms, especially for the acquisition of amino acids and nucleosides from their hosts throughout their life cycles. Many of these transporters have been shown to have sufficiently different substrate affinities from mammalian transporters, making them good carriers for therapeutic agents. In this review, we summarize the knowledge obtained on purine and pyrimidine activities identified in protozoan parasites to date and discuss their importance for the survival of these parasites and as drug carriers, as well as the perspectives of developments in the field.
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Affiliation(s)
- Gustavo D Campagnaro
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, 120 University Place, Glasgow, UK
| | - Harry P de Koning
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, 120 University Place, Glasgow, UK
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11
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Sosa Y, Egbo D, Akabas MH. Impact of Field Isolate Identified Nonsynonymous Single Nucleotide Polymorphisms on Plasmodium falciparum Equilibrative Nucleoside Transporter 1 Inhibitor Efficacy. ACS Infect Dis 2020; 6:205-214. [PMID: 31876139 DOI: 10.1021/acsinfecdis.9b00203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Plasmodium falciparum causes the most severe form of malaria and causes approximately 500 000 deaths per year. P. falciparum parasites resistant to current antimalarial treatments are spreading. Therefore, it is imperative to develop new antimalarial drugs. Malaria parasites are purine auxotrophic. They rely on purine import from the host erythrocyte via Equilibrative Nucleoside Transporters (ENTs). Recently, inhibitors of the P. falciparum ENT1 (PfENT1) that inhibit proliferation of malaria parasites in culture have been identified as promising starting points for antimalarial drug development. Genome sequencing of P. falciparum field isolates has identified nonsynonymous single nucleotide polymorphisms (SNPs) in the gene encoding PfENT1. Here we evaluate the impact of these PfENT1 SNPs on purine substrate affinity and inhibitor efficacy. We expressed each PfENT1-SNP in Saccharomyces cerevisiae. Using PfENT1-SNP-expressing yeast, we characterized the PfENT1 purine substrate affinity using radiolabeled substrate uptake inhibition experiments. Four of the 13 SNPs altered affinity for one or more purines by up to 7-fold. Three of the SNPs reduced the potency of a subset of the inhibitors by up to 7-fold. One SNP, Q284E, reduced the potency of all six inhibitor chemotypes. We tested drug efficacy in available parasite strains containing PfENT1 SNPs. While PfENT1-SNP-expressing yeast had decreased sensitivity to PfENT1 inhibitors, parasite strains containing SNPs showed similar or more potent inhibition of proliferation with all PfENT1 inhibitors. Thus, parasite strains bearing PfENT1 SNPs are not resistant to these PfENT1 inhibitors. This supports PfENT1 as a promising target for further development of novel antimalarial drugs.
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12
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Sosa Y, Deniskin R, Frame IJ, Steiginga MS, Bandyopadhyay D, Graybill TL, Kallal LA, Ouellette MT, Pope AJ, Widdowson KL, Young RJ, Akabas MH. Identification via a Parallel Hit Progression Strategy of Improved Small Molecule Inhibitors of the Malaria Purine Uptake Transporter that Inhibit Plasmodium falciparum Parasite Proliferation. ACS Infect Dis 2019; 5:1738-1753. [PMID: 31373203 DOI: 10.1021/acsinfecdis.9b00168] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Emerging resistance to current antimalarial medicines underscores the importance of identifying new drug targets and novel compounds. Malaria parasites are purine auxotrophic and import purines via the Plasmodium falciparum equilibrative nucleoside transporter type 1 (PfENT1). We previously showed that PfENT1 inhibitors block parasite proliferation in culture. Our goal was to identify additional, possibly more optimal chemical starting points for a drug discovery campaign. We performed a high throughput screen (HTS) of GlaxoSmithKline's 1.8 million compound library with a yeast-based assay to identify PfENT1 inhibitors. We used a parallel progression strategy for hit validation and expansion, with an emphasis on chemical properties in addition to potency. In one arm, the most active hits were tested for human cell toxicity; 201 had minimal toxicity. The second arm, hit expansion, used a scaffold-based substructure search with the HTS hits as templates to identify over 2000 compounds; 123 compounds had activity. Of these 324 compounds, 175 compounds inhibited proliferation of P. falciparum parasite strain 3D7 with IC50 values between 0.8 and ∼180 μM. One hundred forty-two compounds inhibited PfENT1 knockout (pfent1Δ) parasite growth, indicating they also hit secondary targets. Thirty-two hits inhibited growth of 3D7 but not pfent1Δ parasites. Thus, PfENT1 inhibition was sufficient to block parasite proliferation. Therefore, PfENT1 may be a viable target for antimalarial drug development. Six compounds with novel chemical scaffolds were extensively characterized in yeast-, parasite-, and human-erythrocyte-based assays. The inhibitors showed similar potencies against drug sensitive and resistant P. falciparum strains. They represent attractive starting points for development of novel antimalarial drugs.
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Affiliation(s)
| | | | | | - Matthew S. Steiginga
- Platform Technology & Science and Discovery Partners in Academia, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
| | - Deepak Bandyopadhyay
- Platform Technology & Science and Discovery Partners in Academia, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
| | - Todd L. Graybill
- Platform Technology & Science and Discovery Partners in Academia, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
| | - Lorena A. Kallal
- Platform Technology & Science and Discovery Partners in Academia, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
| | - Michael T. Ouellette
- Platform Technology & Science and Discovery Partners in Academia, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
| | - Andrew J. Pope
- Platform Technology & Science and Discovery Partners in Academia, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
| | - Katherine L. Widdowson
- Platform Technology & Science and Discovery Partners in Academia, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
| | - Robert J. Young
- Platform Technology & Science and Discovery Partners in Academia, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
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13
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Kokina A, Ozolina Z, Liepins J. Purine auxotrophy: Possible applications beyond genetic marker. Yeast 2019; 36:649-656. [PMID: 31334866 DOI: 10.1002/yea.3434] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 07/12/2019] [Accepted: 07/16/2019] [Indexed: 01/09/2023] Open
Abstract
Exploring new drug candidates or drug targets against many illnesses is necessary as "traditional" treatments lose their effectivity. Cancer and sicknesses caused by protozoan parasites are among these diseases. Cell purine metabolism is an important drug target. Theoretically, inhibiting purine metabolism could stop the proliferation of unwanted cells. Purine metabolism is similar across all eukaryotes. However, some medically important organisms or cell lines rely on their host purine metabolism. Protozoans causing malaria, leishmaniasis, or toxoplasmosis are purine auxotrophs. Some cancer forms have also lost the ability to synthesize purines de novo. Budding yeast can serve as an effective model for eukaryotic purine metabolism, and thus, purine auxotrophic strains could be an important tool. In this review, we present the common principles of purine metabolism in eukaryotes, effects of purine starvation in eukaryotic cells, and purine-starved Saccharomyces cerevisiae as a model for purine depletion-elicited metabolic states with applications in evolution studies and pharmacology. Purine auxotrophic yeast strains behave differently when growing in media with sufficient supplementation with adenine or in media depleted of adenine (starvation). In the latter, they undergo cell cycle arrest at G1/G0 and become stress resistant. Importantly, similar effects have also been observed among parasitic protozoans or cancer cells. We consider that studies on metabolic changes caused by purine auxotrophy could reveal new options for parasite or cancer therapy. Further, knowledge on phenotypic changes will improve the use of auxotrophic strains in high-throughput screening for primary drug candidates.
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Affiliation(s)
- Agnese Kokina
- Institute of Microbiology and Biotechnology, University of Latvia, Riga, Latvia
| | - Zane Ozolina
- Institute of Microbiology and Biotechnology, University of Latvia, Riga, Latvia
| | - Janis Liepins
- Institute of Microbiology and Biotechnology, University of Latvia, Riga, Latvia
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14
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Cheviet T, Lefebvre-Tournier I, Wein S, Peyrottes S. Plasmodium Purine Metabolism and Its Inhibition by Nucleoside and Nucleotide Analogues. J Med Chem 2019; 62:8365-8391. [PMID: 30964283 DOI: 10.1021/acs.jmedchem.9b00182] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Malaria still affects around 200 million people and is responsible for more than 400,000 deaths per year, mostly children in subequatorial areas. This disease is caused by parasites of the Plasmodium genus. Only a few WHO-recommended treatments are available to prevent or cure plasmodial infections, but genetic mutations in the causal parasites have led to onset of resistance against all commercial antimalarial drugs. New drugs and targets are being investigated to cope with this emerging problem, including enzymes belonging to the main metabolic pathways, while nucleoside and nucleotide analogues are also a promising class of potential drugs. This review highlights the main metabolic pathways targeted for the development of potential antiplasmodial therapies based on nucleos(t)ide analogues, as well as the different series of purine-containing nucleoside and nucleotide derivatives designed to inhibit Plasmodium falciparum purine metabolism.
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Affiliation(s)
- Thomas Cheviet
- Institut des Biomolécules Max Mousseron (IBMM), UMR 5247 UM-CNRS-ENSCM , Université Montpellier, Equipe Nucléosides & Effecteurs Phosphorylés , Place E. Bataillon, cc 1704 , 34095 Montpellier , France
| | - Isabelle Lefebvre-Tournier
- Institut des Biomolécules Max Mousseron (IBMM), UMR 5247 UM-CNRS-ENSCM , Université Montpellier, Equipe Nucléosides & Effecteurs Phosphorylés , Place E. Bataillon, cc 1704 , 34095 Montpellier , France
| | - Sharon Wein
- Dynamique des Interactions Membranaires Normales et Pathologiques (DIMNP), UMR 5235 UM-CNRS , Université Montpellier , Place E. Bataillon , 34095 Montpellier , France
| | - Suzanne Peyrottes
- Institut des Biomolécules Max Mousseron (IBMM), UMR 5247 UM-CNRS-ENSCM , Université Montpellier, Equipe Nucléosides & Effecteurs Phosphorylés , Place E. Bataillon, cc 1704 , 34095 Montpellier , France
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15
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Nishtala SN, Arora A, Reyes J, Akabas MH. Accessibility of substituted cysteines in TM2 and TM10 transmembrane segments in the Plasmodium falciparum equilibrative nucleoside transporter PfENT1. J Biol Chem 2019; 294:1924-1935. [PMID: 30541922 DOI: 10.1074/jbc.ra118.006547] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 11/30/2018] [Indexed: 11/06/2022] Open
Abstract
Infection with Plasmodium species parasites causes malaria. Plasmodium parasites are purine auxotrophic. They import purines via an equilibrative nucleoside transporter (ENT). In P. falciparum, the most virulent species, the equilibrative nucleoside transporter 1 (PfENT1) represents the primary purine uptake pathway. This transporter is a potential target for the development of antimalarial drugs. In the absence of a high-resolution structure for either PfENT1 or a homologous ENT, we used the substituted cysteine accessibility method (SCAM) to investigate the membrane-spanning domain structure of PfENT1 to identify potential inhibitor-binding sites. We previously used SCAM to identify water-accessible residues that line the permeation pathway in transmembrane segment 11 (TM11). TM2 and TM10 lie adjacent to TM11 in an ab initio model of a homologous Leishmania donovani nucleoside transporter. To identify TM2 and TM10 residues in PfENT1 that are at least transiently on the water-accessible transporter surface, we assayed the reactivity of single cysteine-substitution mutants with three methanethiosulfonate (MTS) derivatives. Cysteines substituted for 12 of 14 TM2 segment residues reacted with MTS-ethyl-ammonium-biotin (MTSEA-biotin). At eight positions, MTSEA-biotin inhibited transport, and at four positions substrate transport was potentiated. On an α helical wheel projection of TM2, the four positions where potentiation occurred were located in a cluster on one side of the helix. In contrast, although MTSEA-biotin inhibited 9 of 10 TM10 cysteine-substituted mutants, the reactive residues did not form a pattern consistent with either an α helix or β sheet. These results may help identify the binding site(s) of PfENT1 inhibitors.
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Affiliation(s)
| | - Avish Arora
- From the Departments of Physiology and Biophysics
| | - Jorge Reyes
- From the Departments of Physiology and Biophysics
| | - Myles H Akabas
- From the Departments of Physiology and Biophysics, .,Neuroscience, and.,Medicine, Albert Einstein College of Medicine, Bronx, New York 10461
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16
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Abstract
Transition state theory teaches that chemically stable mimics of enzymatic transition states will bind tightly to their cognate enzymes. Kinetic isotope effects combined with computational quantum chemistry provides enzymatic transition state information with sufficient fidelity to design transition state analogues. Examples are selected from various stages of drug development to demonstrate the application of transition state theory, inhibitor design, physicochemical characterization of transition state analogues, and their progress in drug development.
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Affiliation(s)
- Vern L. Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
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17
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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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18
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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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19
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Silva LS, Prado GC, Quintana PG, Heise N, Miranda KR, Torres EJL, Persechini PM, de Sá Pinheiro AA, Schachter J. Plasmodium falciparum invasion and intraerythrocytic development are impaired by 2', 3'-dialdehyde adenosine. Microbes Infect 2017; 20:205-211. [PMID: 29253662 DOI: 10.1016/j.micinf.2017.11.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 11/24/2017] [Indexed: 11/25/2022]
Abstract
Purine nucleotide synthesis in protozoa takes place exclusively via the purine salvage pathway and S-adenosyl-l-homocysteine hydrolase (SAHH) is an important enzyme in the Plasmodium salvage pathway which is not present in erythrocytes. Here, we describe the antimalarial effect of 2'3'-dialdehyde adenosine or oxidized adenosine (oADO), inhibitor of SAHH, on in vitro infection of human erythrocytes by P. falciparum. Treatment of infected erythrocytes with oADO inhibits parasite development and reinvasion of new cells. Erythrocytes pre-treated with oADO have a reduced susceptibility to invasion. Our results suggest that oADO interferes with one or more parasitic enzymes of the purine salvage pathway.
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Affiliation(s)
- Leandro S Silva
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Gustavo C Prado
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Paula G Quintana
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Norton Heise
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Kildare R Miranda
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Eduardo J L Torres
- Departamento de Microbiologia, Imunologia e Parasitologia, Faculdade de Ciências Médicas, Universidade Do Estado Do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Pedro M Persechini
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Ana Acacia de Sá Pinheiro
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Julieta Schachter
- Polo Xerém, Duque de Caxias, Universidade Federal Do Rio de Janeiro, RJ, Brazil.
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20
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Graml A, Ghosh I, König B. Synthesis of Arylated Nucleobases by Visible Light Photoredox Catalysis. J Org Chem 2017; 82:3552-3560. [PMID: 28247755 DOI: 10.1021/acs.joc.7b00088] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Arylated nucleobases were synthesized by visible light photocatalysis using rhodamine 6G as photoredox catalyst and N,N-diisopropylethylamine as sacrificial electron donor. The high redox potential of this catalyst system is achieved by a consecutive photoinduced electron transfer process (conPET) and allows the room temperature conversion of brominated and chlorinated nucleobases or nucleobase precursors as starting materials. In contrast to many transition-metal-based syntheses, a direct C-H arylation of nitrogen-containing halogenated heterocycles is possible without protection of the N-H groups. The method provides a simple, metal-free alternative for the synthesis of biologically interesting arylated heterocycles under mild conditions.
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Affiliation(s)
- Andreas Graml
- Institut für Organische Chemie, Universität Regensburg , Universitätsstrasse 31, D-93053 Regensburg, Germany
| | - Indrajit Ghosh
- Institut für Organische Chemie, Universität Regensburg , Universitätsstrasse 31, D-93053 Regensburg, Germany
| | - Burkhard König
- Institut für Organische Chemie, Universität Regensburg , Universitätsstrasse 31, D-93053 Regensburg, Germany
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21
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Vyas VK, Qureshi G, Ghate M, Patel H, Dalai S. Identification of novel PfDHODH inhibitors as antimalarial agents via pharmacophore-based virtual screening followed by molecular docking and in vivo antimalarial activity. SAR AND QSAR IN ENVIRONMENTAL RESEARCH 2016; 27:427-440. [PMID: 27310104 DOI: 10.1080/1062936x.2016.1189959] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 05/11/2016] [Indexed: 06/06/2023]
Abstract
Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH) catalyses the fourth reaction of de novo pyrimidine biosynthesis in parasites, and represents an important target for the treatment of malaria. In this study, we describe pharmacophore-based virtual screening combined with docking study and biological evaluation as a rational strategy for identification of novel hits as antimalarial agents. Pharmacophore models were established from known PfDHODH inhibitors using the GALAHAD module with IC50 values ranging from 0.033 μM to 142 μM. The best pharmacophore model consisted of three hydrogen bond acceptor, one hydrogen bond donor and one hydrophobic features. The pharmacophore models were validated through receiver operating characteristic and Günere-Henry scoring methods. The best pharmacophore model as a 3D search query was searched against the IBS database. Several compounds with different structures (scaffolds) were retrieved as hit molecules. Among these compounds, those with a QFIT value of more than 81 were docked in the PfDHODH enzyme to further explore the binding modes of these compounds. In silico pharmacokinetic and toxicities were predicted for the best docked molecules. Finally, the identified hits were evaluated in vivo for their antimalarial activity in a parasite inhibition assay. The hits reported here showed good potential to become novel antimalarial agents.
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Affiliation(s)
- V K Vyas
- a Department of Pharmaceutical Chemistry , Institute of Pharmacy, Nirma University , Ahmedabad , India
| | - G Qureshi
- a Department of Pharmaceutical Chemistry , Institute of Pharmacy, Nirma University , Ahmedabad , India
| | - M Ghate
- a Department of Pharmaceutical Chemistry , Institute of Pharmacy, Nirma University , Ahmedabad , India
| | - H Patel
- b Institute of Science, Nirma University , Ahmedabad , India
| | - S Dalai
- b Institute of Science, Nirma University , Ahmedabad , India
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22
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Arora A, Deniskin R, Sosa Y, Nishtala SN, Henrich PP, Kumar TRS, Fidock DA, Akabas MH. Substrate and Inhibitor Specificity of the Plasmodium berghei Equilibrative Nucleoside Transporter Type 1. Mol Pharmacol 2016; 89:678-85. [PMID: 27048953 DOI: 10.1124/mol.115.101386] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 04/04/2016] [Indexed: 12/22/2022] Open
Abstract
Malaria is a critical public health issue in the tropical world, causing extensive morbidity and mortality. Infection by unicellular, obligate intracellular Plasmodium parasites causes malaria. The emergence of resistance to current antimalarial drugs necessitates the development of novel therapeutics. A potential novel drug target is the purine import transporter. Because Plasmodium parasites are purine auxotrophic, they must import purines from their host to fulfill metabolic requirements. They import purines via equilibrative nucleoside transporter 1 (ENT1) homologs. Recently, we used a yeast-based high-throughput screen to identify inhibitors of the P. falciparum ENT1 (PfENT1) that kill P. falciparum parasites in culture. P. berghei infection of mice is an animal model for human malaria. Because P. berghei ENT1 (PbENT1) shares only 60% amino acid sequence identity with PfENT1, we sought to characterize PbENT1 and its sensitivity to our PfENT1 inhibitors. We expressed PbENT1 in purine auxotrophic yeast and used radiolabeled substrate uptake to characterize its function. We showed that PbENT1 transports both purines and pyrimidines. It preferred nucleosides compared with nucleobases. Inosine (IC50 = 3.7 µM) and guanosine (IC50 = 21.3 µM) had the highest affinities. Our recently discovered PfENT1 inhibitors were equally effective against both PbENT1- and PfENT1-mediated purine uptake. The PfENT1 inhibitors are at least 10-fold more potent against PfENT1 than human hENT1. They kill P. berghei parasites in 24-hour ex vivo culture. Thus, the P. berghei murine malaria model may be useful to evaluate the efficacy of PfENT1 inhibitors in vivo and their therapeutic potential for treatment of malaria.
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Affiliation(s)
- Avish Arora
- Departments of Physiology and Biophysics (A.A., R.D., Y.S., S.N.N., M.H.A.) and Neuroscience and Medicine (M.H.A.), Albert Einstein College of Medicine, Bronx, New York; and Departments Microbiology and Immunology (P.P.H., T.R.S.K., D.A.F.) and Medicine (D.A.F.), Columbia University Medical Center, New York, New York
| | - Roman Deniskin
- Departments of Physiology and Biophysics (A.A., R.D., Y.S., S.N.N., M.H.A.) and Neuroscience and Medicine (M.H.A.), Albert Einstein College of Medicine, Bronx, New York; and Departments Microbiology and Immunology (P.P.H., T.R.S.K., D.A.F.) and Medicine (D.A.F.), Columbia University Medical Center, New York, New York
| | - Yvett Sosa
- Departments of Physiology and Biophysics (A.A., R.D., Y.S., S.N.N., M.H.A.) and Neuroscience and Medicine (M.H.A.), Albert Einstein College of Medicine, Bronx, New York; and Departments Microbiology and Immunology (P.P.H., T.R.S.K., D.A.F.) and Medicine (D.A.F.), Columbia University Medical Center, New York, New York
| | - Sita Nirupama Nishtala
- Departments of Physiology and Biophysics (A.A., R.D., Y.S., S.N.N., M.H.A.) and Neuroscience and Medicine (M.H.A.), Albert Einstein College of Medicine, Bronx, New York; and Departments Microbiology and Immunology (P.P.H., T.R.S.K., D.A.F.) and Medicine (D.A.F.), Columbia University Medical Center, New York, New York
| | - Philipp P Henrich
- Departments of Physiology and Biophysics (A.A., R.D., Y.S., S.N.N., M.H.A.) and Neuroscience and Medicine (M.H.A.), Albert Einstein College of Medicine, Bronx, New York; and Departments Microbiology and Immunology (P.P.H., T.R.S.K., D.A.F.) and Medicine (D.A.F.), Columbia University Medical Center, New York, New York
| | - T R Santha Kumar
- Departments of Physiology and Biophysics (A.A., R.D., Y.S., S.N.N., M.H.A.) and Neuroscience and Medicine (M.H.A.), Albert Einstein College of Medicine, Bronx, New York; and Departments Microbiology and Immunology (P.P.H., T.R.S.K., D.A.F.) and Medicine (D.A.F.), Columbia University Medical Center, New York, New York
| | - David A Fidock
- Departments of Physiology and Biophysics (A.A., R.D., Y.S., S.N.N., M.H.A.) and Neuroscience and Medicine (M.H.A.), Albert Einstein College of Medicine, Bronx, New York; and Departments Microbiology and Immunology (P.P.H., T.R.S.K., D.A.F.) and Medicine (D.A.F.), Columbia University Medical Center, New York, New York
| | - Myles H Akabas
- Departments of Physiology and Biophysics (A.A., R.D., Y.S., S.N.N., M.H.A.) and Neuroscience and Medicine (M.H.A.), Albert Einstein College of Medicine, Bronx, New York; and Departments Microbiology and Immunology (P.P.H., T.R.S.K., D.A.F.) and Medicine (D.A.F.), Columbia University Medical Center, New York, New York
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Targeting the Plasmodium vivax equilibrative nucleoside transporter 1 (PvENT1) for antimalarial drug development. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2015; 6:1-11. [PMID: 26862473 PMCID: PMC4706624 DOI: 10.1016/j.ijpddr.2015.11.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 11/18/2015] [Accepted: 11/25/2015] [Indexed: 11/26/2022]
Abstract
Infection with Plasmodium falciparum and vivax cause most cases of malaria. Emerging resistance to current antimalarial medications makes new drug development imperative. Ideally a new antimalarial drug should treat both falciparum and vivax malaria. Because malaria parasites are purine auxotrophic, they rely on purines imported from the host erythrocyte via Equilibrative Nucleoside Transporters (ENTs). Thus, the purine import transporters represent a potential target for antimalarial drug development. For falciparum parasites the primary purine transporter is the P. falciparum Equilibrative Nucleoside Transporter Type 1 (PfENT1). Recently we identified potent PfENT1 inhibitors with nanomolar IC50 values using a robust, yeast-based high throughput screening assay. In the current work we characterized the Plasmodium vivax ENT1 (PvENT1) homologue and its sensitivity to the PfENT1 inhibitors. We expressed a yeast codon-optimized PvENT1 gene in Saccharomyces cerevisiae. PvENT1-expressing yeast imported both purines ([3H]adenosine) and pyrimidines ([3H]uridine), whereas wild type (fui1Δ) yeast did not. Based on radiolabel substrate uptake inhibition experiments, inosine had the lowest IC50 (3.8 μM), compared to guanosine (14.9 μM) and adenosine (142 μM). For pyrimidines, thymidine had an IC50 of 183 μM (vs. cytidine and uridine; mM range). IC50 values were higher for nucleobases compared to the corresponding nucleosides; hypoxanthine had a 25-fold higher IC50 than inosine. The archetypal human ENT1 inhibitor 4-nitrobenzylthioinosine (NBMPR) had no effect on PvENT1, whereas dipyridamole inhibited PvENT1, albeit with a 40 μM IC50, a 1000-fold less sensitive than human ENT1 (hENT1). The PfENT1 inhibitors blocked transport activity of PvENT1 and the five known naturally occurring non-synonymous single nucleotide polymorphisms (SNPs) with similar IC50 values. Thus, the PfENT1 inhibitors also target PvENT1. This implies that development of novel antimalarial drugs that target both falciparum and vivax ENT1 may be feasible. PvENT1 can be functionally expressed in Saccharomyces cerevisiae. PvENT1 transports purine and pyrimidine nucleosides and nucleobases but does not transport nucleotides. PvENT1 is inhibited by recently described PfENT1 inhibitors with similar potency. Identified PvENT1 non-synonymous SNPs do not change PfENT1 inhibitor potency. Plasmodium ENTs may be feasible target for development of novel antimalarial drugs.
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Key Words
- ACT, Artemisinin-based Combination Therapies
- CQ, chloroquine
- Drug development
- EC50, concentration causing 50% of maximal effect
- ENT, equilibrative nucleoside transporter
- EV, empty vector
- HTS, high throughput screen
- IC50, concentration causing 50% inhibition
- Malaria
- NBMPR, 4-nitrobenzylthioinosine
- Nucleoside/nucleobase transport
- Parasite
- PfENT1, P. falciparum ENT type 1
- Plasmodium vivax
- Purines
- PvENT1, P. vivax ENT type 1
- SDM, synthetic defined media
- SNP, single nucleotide polymorphism
- Single-nucleotide polymorphism (SNP)
- Transporter
- WHO, World Health Organization
- WT, wild type
- hENT1, human ENT type 1
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