Abstract
BACKGROUND: The emergence of widespread resistance of Plasmodium species to most antimalarial drugs has led to a more vigorous and concerted research on traditional medicinal plants for the treatment of malaria. OBJECTIVE OF STUDY: The study was aimed to investigate the in vitro antiplasmodial activity of crude ethanolic and aqueous extracts of Phyllanthus amarus against clinical isolates of Plasmodium falciparum in Northwestern Nigeria. MATERIALS AND METHODS: The plant was extracted using two solvents, water and ethanol, where a high yield was obtained from the aqueous extracts (11.9%) as compared to the ethanolic extract (9.64%). The extracts were evaluated in vitro at concentrations of 6.25, 12.5, 25, 50, and 100 μg/ml, and the level of potency in each case was expressed as the concentration of the extract that exhibited a 50% reduction of the parasites relative to control (100%) parasitemia. Artemether-lumefantrine was used as a positive standard in the assay. RESULTS: All extracts showed a significant reduction in parasite growth relative to control (P ≤ 0.05). Ethanolic extract exhibited a higher antiplasmodial activity of 76.8%, half-maximal inhibitory concentration (IC(50)) of 5.80 μg/ml, and aqueous extract had an activity of 75.3%, IC(50) of 7.94 μg/ml. Both extracts exhibited very active antiplasmodial activity. Oral acute toxicity test in the doses of 500, 1000, and 1500 mg/kg showed no sign of toxicity on albino mice after 48 h. CONCLUSION: Although there was an increase in appetite after 24 and 48 h, the findings from this study show that P. amarus possesses a promising antimalarial activity which can be exploited for malaria therapy and justifies the traditional use of the plant in malaria treatment.