Antimalarial activity of fractions isolated from Albizia gummifera and Aspilia mossambicensis crude extracts.

To identify the fractions of medicinal plant extracts containing the highest concentration of antimalarial principles, we tested the antimalarial activities of the crude or total extracts and two fractions from Albizia gummifera (Leguminosae) and three fractions from Aspilia mossambicencis (Compositae) against laboratory adapted isolates of Plasmodium falciparum in vitro using the 3H-hypoxanthine uptake assay. Chloroquine was used as a reference antimalarial drug. The mean 50% inhibitory concentrations (IC50s) of A. gummifera total extract and fraction were both <2.2 microg/ml for three P. falciparum isolates while the mean IC50 of A. gummifera f raction-2 was higher (5.0+2.9sd) for the same isolates. Aspilia mossambicensis total extract and fractions-1,4 and 5 had mean IC50 values of 96.6+/-32.5,38.6+/-23.0,142.5+/-79.6 and >1250.0 microg/ml, respectively, against four P. falciparum isolates. These results show that fraction-1 of either A. gummifera or A, mossambicensis had the highest concentration of antimalarial principles. We now plan to concentrate our efforts on these promising fractions in order to isolate pure compounds which could eventually be used to effectively treat malaria.