Oplodiol and nitidine as potential inhibitors of Plasmodium falciparum dihydrofolate reductase: insights from a computational study.

Many natural products have been shown to possess antiplasmodial activities, but their protein targets are unknown. This work employed molecular docking and molecular dynamics simulations to explore the inhibitory activity of some antiplasmodial natural products against wild-type and mutant strains of Plasmodium falciparum dihydrofolate reductase ( Pf DHFR). From the molecular docking study, 6 ligands preferentially bind at the active site of the DHFR domain with binding energies ranging from -6.4 to -9.5 kcal/mol. Interactions of compounds with MET55 and PHE58 were mostly observed in the molecular docking study. From the molecular dynamics study, the binding of 2 of the ligands-nitidine and oplodiol-was observed to be stable against all tested strains of Pf DHFR. The average binding free energy of oplodiol in complex with the various Pf DHFR strains was -93.701 kJ/mol whereas that of nitidine was -106.206 kJ/mol. The impressive in silico activities of the 2 compounds suggest they could be considered for development as potential antifolate agents.Communicated by Ramaswamy H. Sarma.