<i>In vitro</i> antiamoebic and antiplasmodial activities of alkaloids isolated from <i>Alstonia angustifolia</i> roots

Abstract

Abstract Nine alkaloids from Alstonia angustifolia have been assessed for antiprotozoal activities against Entamoeba histolytica and Plasmodium falciparum in vitro. Three dimeric alkaloids, macrocarpamine, macralstonine acetate (semisynthetic) and villastonine were found to possess significant activity against both protozoans, but were 4–8 times less potent than emetine against E. histolytica and 15–50 times less potent than chloroquine against P. falciparum. The monomeric alkaloids, alstonerine, alstophylline, 11‐methoxyakuammicine, norfluorocurarine, pleiocarpamine and vincamajine were all considerably less active than the dimers: macralstonine base was found to be inactive.