Potent antimalarial activity of the alkaloid nitidine, isolated from a Kenyan herbal remedy.

Bioassay-guided fractionation of extracts of Toddalia asiatica, a plant used by the Pokot tribe of Kenya to treat fevers, has yielded the alkaloid nitidine as the major antimalarial component. Fractions containing nitidine have in vitro 50% inhibitory concentrations against Plasmodium falciparum in the range of 9 to 108 ng/ml for a range of chloroquine-susceptible and -resistant strains. The results show a lack of cross-resistance between chloroquine and nitidine.