| Summary: | <p>Abstract</p> <p>Background</p> <p>Malaria is a major public health threat in Africa, and traditional medicine continues to play a key role in its control especially in rural areas. A bioassay-guided fractionation was carried out in order to evaluate the anti-malarial potential and the safety of the methanol extract of the <it>Hypericum lanceolatum </it>stem bark.</p> <p>Methods</p> <p>The anti-plasmodial activity was assayed by the lactate dehydrogenase method (pLDH) against the multidrug-resistant W2mef laboratory strain, and a field isolate (SHF4) of <it>Plasmodium falciparum</it>. Cytotoxicity tests were carried out using the LLC-MK2 monkey kidney epithelial cells.</p> <p>Results</p> <p>Five compounds were isolated from the most active and least cytotoxic ethylacetate sub-extract: betulinic acid (HLT1), 2,2',5,6'-tetrahydroxybenzophenone (HLT2), 5-hydroxy-3-methoxyxanthone (HLT3), 3-hydroxy-5-methoxyxanthone (HLT4) and HLT0 (yet to be identified). Three of the tested compounds presented significant anti-plasmodial activities (with 50% inhibitory concentration, IC<sub>50 </sub>< 5 μM), with 5-hydroxy-3-methoxyxanthone exerting the highest activity, followed by HLT0 and betulinic acid. All the compounds with significant anti-plasmodial activity were non-cytotoxic, except betulinic acid which showed a 50% cytotoxic concentration, CC<sub>50 </sub>of 25 μg/mL.</p> <p>Conclusions</p> <p>These findings justify the use of <it>H. lanceolatum </it>stem bark as anti-malarial by traditional healers of Western Cameroon, and could constitute a good basis for further studies towards development of new drug candidates or phytomedicines for malaria.</p>
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