Antiplasmodial compounds from Cassia siamea stem bark extract.

Cassia siamea L. (Fabaceae) was identified from the southwest Nigerian ethnobotany as a remedy for febrile illness. This led to the bioassay-guided fractionation of stem bark of the plant extract, using the parasite lactate dehydrogenase assay and multi-resistant strain of Plasmodium falciparum (K1) for assessing the in vitro antimalarial activity. Emodin and lupeol were isolated from the ethyl acetate fraction by a combination of chromatographic techniques. The structures of the compounds were determined by spectroscopy, co-spotting with authentic samples and comparison with literature data. Both compounds were found to be the active principles responsible for the antiplasmodial property with IC(50) values of 5 microg/mL, respectively.

In vitro and in vivo antimalarial studies of Striga hermonthica and Tapinanthus sessilifolius extracts.

The antimalarial activities of the methanol extracts of Striga hermonthica (whole plant) and Tapinanthus sessilifolius (leaves), commonly used in Northern Nigeria for the treatment of malaria, were evaluated. In the in vitro antiplasmodial analysis, the extracts of T. sessilifolius and S. hermonthica utilized in the study, displayed mild to weak activities with IC50 values of 200.5 and 274.8 microg/ml respectively. This was investigated, using the multidrug resistant Plasmodium falciparum, K1 strain, in the parasite lactate dehydrogenase assay. The murine model in vivo antimalarial activity of the tested extracts, using chloroquine-sensitive Plasmodium berghei (ANKA P1), in the 4-day suppressive test, showed that both plants had intrinsic antimalarial properties, that were dose-dependent. At a dose of 400mg/kg weight of mice, extract of S. hermonthica exhibited a higher intrinsic antimalarial activity (68.5 % suppression) than that of T. sessilifolius (51.3 %). Chloroquine, the standard reference drug, had an average suppression of 78.0 % at a dose of 10 mg/kg weight of mice while normal saline was used as control. Preliminary phytochemical screening of the extracts indicated the presence ofsaponins, tannins, flavonoids, volatile oils and cardiac glycosides.