Antiprotozoal activity of aporphine alkaloids isolated from Unonopsis buchtienii (Annonaceae).

On a preliminary screening, substantial leishmanicidal activity was observed for the petroleum ether and alkaloidal extracts of the stem bark of Unonopsis buchtienii, the alkaloids and sterols isolated from these were studied. Of the alkaloids, liriodenine exhibited the highest activity against Leishmania major and L donovani (IC100 = 3.12 micrograms/mL). On the other hand, O-methylmoschatoline and the petroleum ether extract without alkaloids showed an interesting in vitro activity against Trypanosoma brucei with an IC100 of 6.25 micrograms/mL. The highest cytotoxic activities were found with the petroleum ether extracts without alkaloids and with all alkaloids isolated (IC50 < 9 micrograms/mL for Vero cell line).