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An In Silico Study of the Interactions of Alkaloids from Cryptolepis sanguinolenta with Plasmodium falciparum Dihydrofolate Reductase and Dihydroorotate Dehydrogenase. J CHEM-NY 2022. [DOI: 10.1155/2022/5314179] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Plasmodium falciparum dihydrofolate reductase (PfDHFR) and dihydroorotate dehydrogenase (PfDHODH) are essential for Plasmodium falciparum growth and development, and have been validated as targets for the development of new antimalarial agents. Several alkaloids isolated from Cryptolepis sanguinolenta have been reported to have antiplasmodial activity, but their protein targets are unknown. Therefore, molecular docking and molecular dynamics simulations were used to investigate the interactions and stability of the alkaloids with PfDHFR and PfDHODH. Based on physicochemical characteristics, alkaloids were grouped as sterically bulky (sb) or planar (pg). Docking results revealed strong binding affinities (−6.0 to −13.4 kcal/mol) of the alkaloids against PfDHODH and various strains of PfDHFR while interacting with key residues such as Asp54 and Phe58 in PfDHFR. The pg alkaloids had high binding affinity and preference for the inhibitor binding domain over the flavin mononucleotide (FMN) binding domain in PfDHODH due to size considerations. From the molecular dynamics trajectories, protein-alkaloid complexes were stable throughout the simulation, with supporting evidence from root mean square deviations, root mean square fluctuations, radius of gyration, free binding energies, and other parameters. We report herein that biscryptolepine and cryptomisrine (sb class), as well as cryptolepinone, cryptoheptine, cryptolepine, and neocryptolepine (pg class), are capable of inhibiting PfDHFR effectively in pyrimethamine sensitive and resistant cells. Also, our results show that alkaloids of the pg class can inhibit PfDHODH as FMN decoys, as well as direct enzyme inhibitors, thereby halting crucial protein function.
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In silico studies of semi-synthetic benzo[a]phenazines as inhibitors of dihydrofolate reductase from Plasmodium falciparum. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.130404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Nattee C, Khamsemanan N, Lawtrakul L, Toochinda P, Hannongbua S. A novel prediction approach for antimalarial activities of Trimethoprim, Pyrimethamine, and Cycloguanil analogues using extremely randomized trees. J Mol Graph Model 2016; 71:13-27. [PMID: 27835827 DOI: 10.1016/j.jmgm.2016.09.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 09/19/2016] [Accepted: 09/20/2016] [Indexed: 10/20/2022]
Abstract
Malaria is still one of the most serious diseases in tropical regions. This is due in part to the high resistance against available drugs for the inhibition of parasites, Plasmodium, the cause of the disease. New potent compounds with high clinical utility are urgently needed. In this work, we created a novel model using a regression tree to study structure-activity relationships and predict the inhibition constant, Ki of three different antimalarial analogues (Trimethoprim, Pyrimethamine, and Cycloguanil) based on their molecular descriptors. To the best of our knowledge, this work is the first attempt to study the structure-activity relationships of all three analogues combined. The most relevant descriptors and appropriate parameters of the regression tree are harvested using extremely randomized trees. These descriptors are water accessible surface area, Log of the aqueous solubility, total hydrophobic van der Waals surface area, and molecular refractivity. Out of all possible combinations of these selected parameters and descriptors, the tree with the strongest coefficient of determination is selected to be our prediction model. Predicted Ki values from the proposed model show a strong coefficient of determination, R2=0.996, to experimental Ki values. From the structure of the regression tree, compounds with high accessible surface area of all hydrophobic atoms (ASA_H) and low aqueous solubility of inhibitors (Log S) generally possess low Ki values. Our prediction model can also be utilized as a screening test for new antimalarial drug compounds which may reduce the time and expenses for new drug development. New compounds with high predicted Ki should be excluded from further drug development. It is also our inference that a threshold of ASA_H greater than 575.80 and Log S less than or equal to -4.36 is a sufficient condition for a new compound to possess a low Ki.
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Affiliation(s)
- Cholwich Nattee
- Sirindhorn International Institute of Technology, Thammasat University, Thailand
| | | | - Luckhana Lawtrakul
- Sirindhorn International Institute of Technology, Thammasat University, Thailand
| | - Pisanu Toochinda
- Sirindhorn International Institute of Technology, Thammasat University, Thailand
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Mokmak W, Chunsrivirot S, Hannongbua S, Yuthavong Y, Tongsima S, Kamchonwongpaisan S. Molecular dynamics of interactions between rigid and flexible antifolates and dihydrofolate reductase from pyrimethamine-sensitive and pyrimethamine-resistant Plasmodium falciparum. Chem Biol Drug Des 2014; 84:450-61. [PMID: 24716467 DOI: 10.1111/cbdd.12334] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 03/04/2014] [Accepted: 04/03/2014] [Indexed: 01/16/2023]
Abstract
Currently, the usefulness of antimalarials such as pyrimethamine (PYR) is drastically reduced due to the emergence of resistant Plasmodium falciparum (Pf) caused by its dihydrofolate reductase (PfDHFR) mutations, especially the quadruple N51I/C59R/S108N/I164L mutations. The resistance was due to the steric conflict of PYR with S108N. WR99210 (WR), a dihydrotriazine antifolate with a flexible side chain that can avoid such conflict, can overcome this resistance through tight binding with the mutant. To understand factors contributing to different binding affinities of PYR/WR to the wild type (WT) and quadruple mutant (QM), we performed simulations on WR-WT, WR-QM, PYR-WT, and PYR-QM complexes and found that Ile14 and Asp54 were crucial for PYR/WR binding to PfDHFR due to strong hydrogen bonds. The quadruple mutations cause PYR to form, on average, fewer hydrogen bonds with Ile14 and Leu164, and to be displaced from its optimal orientation for Asp54 interaction. The predicted binding affinity ranking (WR-QM ≈ WR-WT ≈ PYR-WT >> PYR-QM) reasonably agrees with the inhibition constant (K(i)) ranking. Our results reveal important residues for tight binding of PYR/WR to WT/QM, which may be used to evaluate the inhibition effectiveness of antimalarials and to provide fundamental information for designing new drugs effective against drug-resistant P. falciparum.
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Affiliation(s)
- Wanwimon Mokmak
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Klong Luang, Pathum Thani, 12120, Thailand
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Hecht D, Fogel GB. Modeling the evolution of drug resistance in malaria. J Comput Aided Mol Des 2012; 26:1343-53. [PMID: 23179493 PMCID: PMC3535480 DOI: 10.1007/s10822-012-9618-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 11/08/2012] [Indexed: 01/12/2023]
Abstract
Plasmodium falciparum, the causal agent of malaria, continues to evolve resistance to frontline therapeutics such as chloroquine and sulfadoxine-pyrimethamine. Here we study the amino acid replacements in dihydrofolate reductase (DHFR) that confer resistance to pyrimethamine while still binding the natural DHFR substrate, 7,8-dihydrofolate, and cofactor, NADPH. The chain of amino acid replacements that has led to resistance can be inferred in a computer, leading to a broader understanding of the coevolution between the drug and target. This in silico approach suggests that only a small set of specific active site replacements in the proper order could have led to the resistant strains in the wild today. A similar approach can be used on any target of interest to anticipate likely pathways of future resistance for more effective drug development.
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Affiliation(s)
- David Hecht
- Southwestern College, 900 Otay Lakes Rd., Chula Vista, CA 91910, USA
| | - Gary B. Fogel
- Natural Selection, Inc., 9330 Scranton Rd., San Diego, CA 92121, USA
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Basak SC, Mills D. Quantitative structure-activity relationships for cycloguanil analogs as PfDHFR inhibitors using mathematical molecular descriptors. SAR AND QSAR IN ENVIRONMENTAL RESEARCH 2010; 21:215-229. [PMID: 20544548 DOI: 10.1080/10629361003770951] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Computed molecular descriptors were used to develop quantitative structure-activity relationships (QSARs) for binding affinities (K(i)) for a set of 58 cycloguanil (2,4-diamino-1,6-dihydro-1,3,5-triazine) analogues for dihydrofolate reductase (DHFR) enzyme extracted from wild and A16V+S108T mutant type (a double mutation) malaria parasite Plasmodium falciparum (Pf). High-quality models were obtained in both cases. The results of statistical analyses show that ridge regression (RR) outperformed the two other modelling methods, principal component regression (PCR) and partial least squares (PLS). For both enzymes, recognition of the inhibitors was based on four broad categories of descriptors encoding information on: (1) the electronic character of the various atoms in the molecule, (2) the size and shape of the structure, (3) the degree of branching in the molecular skeleton, and (4) two to five atom molecular fragments with aliphatic carbon at one end and aliphatic or aromatic carbon or nitrogen at the other end. The subsets of influential descriptors underlying the QSARs for the wild versus the mutant DHFR are quite non-overlapping. This indicates that the two enzymes recognize the inhibitor molecules on the basis of mutually distinct structural attributes. Such differential QSARs can be useful in the design of novel drugs active against malaria parasites which are growing in resistant to existing chemotherapeutic agents.
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Affiliation(s)
- S C Basak
- Center for Water and the Environment, Natural Resources Research Institute, University of Minnesota Duluth, Duluth, USA.
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Sivaprakasam P, Tosso PN, Doerksen RJ. Structure-activity relationship and comparative docking studies for cycloguanil analogs as PfDHFR-TS inhibitors. J Chem Inf Model 2009; 49:1787-96. [PMID: 19588935 DOI: 10.1021/ci9000663] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Drug resistance acquired by Plasmodium falciparum (Pf) is a major problem in the treatment and control of malaria. One of the major examples of drug resistance is that caused by mutations in the active site of dihydrofolate reductase (DHFR) of Pf (PfDHFR-TS). A double mutation, A16V+S108T, is specific for resistance to the marketed drug cycloguanil. In this study, we used 58 cycloguanil (2,4-diamino-1,6-dihydro-1,3,5-triazine) derivatives to explore the relationship between various physicochemical properties and reported binding affinity data on wild-type and mutant-type A16V+S108T. Using the Hansch 2D-quantitative structure-activity relationship method, we obtained a parabolic relationship of hydrophobicity of substituents at the N1-phenyl ring with the wild-type binding affinity data. Hydrophobicity being a key property for wild-type binding affinity data, we found steric factors to be crucial for A16V+S108T mutant resistance. We investigated FlexX, GOLD, Glide and Molegro virtual docking programs and 13 different scoring functions on 10 of the cycloguanil derivatives to evaluate which program was best for reproducing the experimental binding mode and correlating the docking scores with the reported binding affinity data. We identified GOLD, using its GoldScore fitness function, as the most accurate docking program for predicting binding affinity data of cycloguanil derivatives to DHFR and Molegro virtual docker, with its template docking algorithm and MolDock [GRID] scoring function, as most accurate for reproducing the experimental binding mode of a reference ligand that is structurally similar to the cycloguanil derivatives studied. We also report an interaction index which best describes the structure-activity relationships exhibited by these analogs in terms of PfDHFR-TS active site interactions.
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Affiliation(s)
- Prasanna Sivaprakasam
- Department of Medicinal Chemistry, School of Pharmacy, University of Mississippi, 417 Faser Hall, University, Mississippi 38677-1848, USA
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Hecht D, Fogel GB. A Novel In Silico Approach to Drug Discovery via Computational Intelligence. J Chem Inf Model 2009; 49:1105-21. [DOI: 10.1021/ci9000647] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- David Hecht
- Southwestern College, 900 Otay Lakes Road, Chula Vista, California 91910, and Natural Selection, Inc., 9330 Scranton Road, Suite 150, San Diego, California 92121
| | - Gary B. Fogel
- Southwestern College, 900 Otay Lakes Road, Chula Vista, California 91910, and Natural Selection, Inc., 9330 Scranton Road, Suite 150, San Diego, California 92121
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Dasgupta T, Chitnumsub P, Kamchonwongpaisan S, Maneeruttanarungroj C, Nichols SE, Lyons TM, Tirado-Rives J, Jorgensen WL, Yuthavong Y, Anderson KS. Exploiting structural analysis, in silico screening, and serendipity to identify novel inhibitors of drug-resistant falciparum malaria. ACS Chem Biol 2009; 4:29-40. [PMID: 19146480 DOI: 10.1021/cb8002804] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Plasmodium falciparum thymidylate synthase-dihydrofolate reductase (TS-DHFR) is an essential enzyme in folate biosynthesis and a major malarial drug target. This bifunctional enzyme thus presents different design approaches for developing novel inhibitors against drug-resistant mutants. We performed a high-throughput in silico screen of a database of diverse, drug-like molecules against a non-active-site pocket of TS-DHFR. The top compounds from this virtual screen were evaluated by in vitro enzymatic and cellular culture studies. Three compounds active to 20 microM IC(50)'s in both wildtype and antifolate-resistant P. falciparum parasites were identified; moreover, no inhibition of human DHFR enzyme was observed, indicating that the inhibitory effects appeared to be parasite-specific. Notably, all three compounds had a biguanide scaffold. However, relative free energy of binding calculations suggested that the compounds might preferentially interact with the active site over the screened non-active-site region. To resolve the two possible modes of binding, co-crystallization studies of the compounds complexed with TS-DHFR enzyme were performed. Surprisingly, the structural analysis revealed that these novel, biguanide compounds do indeed bind at the active site of DHFR and additionally revealed the molecular basis by which they overcome drug resistance. To our knowledge, these are the first co-crystal structures of novel, biguanide, non-WR99210 compounds that are active against folate-resistant malaria parasites in cell culture.
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Affiliation(s)
- Tina Dasgupta
- Department of Pharmacology, Yale University School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520
| | - Penchit Chitnumsub
- BIOTEC Central Research Unit, National Science and Technology Development Agency, Science Park, 113 Phaholyothin Road, Klong Luang, Pathumthani 12120, Thailand
| | - Sumalee Kamchonwongpaisan
- BIOTEC Central Research Unit, National Science and Technology Development Agency, Science Park, 113 Phaholyothin Road, Klong Luang, Pathumthani 12120, Thailand
| | - Cherdsak Maneeruttanarungroj
- BIOTEC Central Research Unit, National Science and Technology Development Agency, Science Park, 113 Phaholyothin Road, Klong Luang, Pathumthani 12120, Thailand
| | - Sara E. Nichols
- Interdepartmental Program in Computational Biology and Bioinformatics, Yale University, 300 George Street Suite 501, New Haven, Connecticut 06511
| | - Theresa M. Lyons
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520
| | - Julian Tirado-Rives
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520
| | - William L. Jorgensen
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520
| | - Yongyuth Yuthavong
- BIOTEC Central Research Unit, National Science and Technology Development Agency, Science Park, 113 Phaholyothin Road, Klong Luang, Pathumthani 12120, Thailand
| | - Karen S. Anderson
- Department of Pharmacology, Yale University School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520
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Fogel GB, Cheung M, Pittman E, Hecht D. In silico screening against wild-type and mutant Plasmodium falciparum dihydrofolate reductase. J Mol Graph Model 2008; 26:1145-52. [DOI: 10.1016/j.jmgm.2007.10.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2007] [Revised: 10/11/2007] [Accepted: 10/11/2007] [Indexed: 12/21/2022]
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