Virtual Screening of Selected Phytochemicals From Four Antimalarial Plants Predicted Potential Inhibitors of Wild Type and Mutant Forms of Dihydrofolate Reductase-Thymidylate Synthase in <em>Plasmodium sp</em>.

Resistance to Pyrimethamine, an antimalarial medicine has been reported to be due to mutations in Dihydrofolate reductase-thymidylate synthase (DHFR-TS). Phytochemicals, particularly from plants that been used in ethnomedicine, have been reported to have privileged structures that might bind strongly to the mutants of DHFR-TS. The aim of this study is to identify phytochemicals of Acalypha wilkesiana, Cymbopogon citratus, Azadirachta indica, and Morinda lucida with high binding affinities for the Plasmodium falciparum DHFR-TS. The three-dimensional structures of the phytochemicals, wide type and mutant forms of DHTR-TS were obtained from PubChem and Protein Databank (PDB) respectively. They were appropriately prepared and molecular docking simulations was implemented to predict binding affinities of the phytochemicals to the wildtype and mutant forms of DHTR-TS. Druglikeness assessment was implemented to triage the top binding phytochemicals and molecular dynamics simulations was done to establish the stability of the interaction of the top-ranked phytochemical with one of the mutants of DHFR-TS. Nineteen phytochemicals showed higher binding affinities to both the wild type and mutant forms DHFR-TS than Pyrimethamine. Molecular dynamics revealed that the receptor-ligand binding of luteolin, the top-ranked, drug like phytochemicals, to the quadruple mutant was stable.