SCREENING FOR in vitro ACTIVITY OF EXTRACTS OF Picralima nitida AGAINST Plasmodium falciparum.
The intolerable impact of malaria has been attributed to the increasing resistance of Plasmodium parasite to chemoprophylactic and chemotherapeutic agents. The need for drugs with novel modes of action prompted this research, to discover a new anti-malaria agent from this medicinal plant (Picralima nitida), after discovering that the plant is used traditionally to treat malaria in Nigeria. Crude methanolic and aqueous extracts of the leave, seed and pulp of P.nitida plant were screened for its phytochemical constituents. Different concentrations of the crude extracts were tested on trophozoites mainly ring form. The acute toxicity was also evaluated on white albino mice. The mice were treated orally with single doses of 10,100, 1000, 1600, 2900, 5000, and 8000 mg/kg body weight of Picralima nitida extracts of the leave, seed, and pulp after being starved for 24hrs. The phytochemical screening of aqueous, and methanol extracts of Picralima nitida revealed the presence of Alkaloids, Anthraquinone, flavonoid, saponin, Tannins, Terpenesr and steroids. The invitro anti-plasmodial activity of the aqueous and methanol extracts of Picralima nitida, displayed a significant reduction in the number of parasitysed cells in the test cultures after 24-30hrs of incubation. The methanolic extract of the leave displayed the highest anti-malaria activity, with IC50 of 15.6 ± 1.2 µg /ml. while the aqueous pulp extract yielded the lowest anti-malaria activity with IC50 of 42.0 ± 1.4 µg/ml. Picralima nitida extracts with the above doses of 5000 and 8000 produced physical signs of toxicity 10hr after administration. The signs include writhing, decreased motor activity, gasping and death. The intensity of these effects was proportional to the dose administered. All the animals treated with 5000 and 8000 mg/kg body weight of the extracts died and the LD50 was calculated to be 3807 mg/kg body weight. This result justifies the traditional use of the plant parts in the treatment of malaria.