Inhibitory Activity and Docking Analysis of Antimalarial Agents from Stemona sp. toward Ferredoxin-NADP+ Reductase from Malaria Parasites.

Ferredoxin-NADP+ reductases (FNRs, EC 1.18.1.2) were found in the plastids of Plasmodium and have been considered as a target for the development of new antimalarial agents. Croomine, epi -croomine, tuberostemonine, javastemonine A, and isoprotostemonine are isolated alkaloids from the roots of Stemona sp. and their inhibitory effect on FNRs from Plasmodium falciparum (Pf FNR) was investigated. Croomine showed the highest level of inhibition (33.9%) of electron transfer from Pf FNR to Pf Fd, while tuberstemonine displayed the highest level of inhibition (55.4%) of diaphorase activity of Pf FNR. Docking analysis represented that croomine is located at the middle position of Pf FNR and Pf Fd. Croomine from S. tuberosa appeared to have potential as an antimalarial agent.