Exploring natural product library as potential target against sterol C-24 methyltransferase protein of <i>Leishmania donovani</i>

Natural product offers an ocean of biologically active compounds that have diverse functionality. Thus, the present study aims for the exploration of natural product molecules for their leishmanicidal potency. Primary evaluation at 50 µM concentration revealed that out of 560 molecules, 38 compounds demonstrated a percentage killing of >50%. Next, the dose-dependent investigation showed that six active hits displayed the IC₅₀ value ranging from 0.47 to 14.2 µM. Further, the molecular docking analysis using the alpha fold structure of Sterol C-24 methyltransferase of <i>Leishmania donovani</i> (LdSMT) (an enzyme absent in mammalian host) unveiled the strong binding affinity with top two hits namely shatavarin IV (-7.9 kcal/mol) and 6-methoxydihydrochelerythrine (-7.6 kcal/mol). Also, <i>in silico</i> studies were supported by the alterations in ergosterol content in the parasites treated with these two potent hits. In conclusion, our study suggests that the two potent hits inhibit the <i>Leishmania</i> parasite growth by hindering sterol biosynthesis.