Phytochemical and antimalarial studies on the methanol root bark extract of Annona senegalensis pers. (annonaceae

Abstract

Phytochemical screening of the methanol root bark extract of Annona senegalensis, a plant known for its numerous ethnomedicinal uses such antimalarial, anticonvulsant, anticancer, antinociceptive and anti-inflammatory properties showed the presence of tannins, saponins, alkaloids, triterpenes, steroids, flavonoids and cardiac glycosides. The column chromatographic analysis of the chloroform fraction of the crude methanol extract led to the isolation of stigmasterol which was elucidated using IR, 1D and 2D NMR analysis. The median oral lethal dose (LD₅₀) was estimated to be 2154 mg/kg, suggesting the extract is relatively toxic at the tested doses. The crude extract produced a significant (p ≤ 0.05) dose - dependent antimalarial activity against Plasmodium berghei in early infection (suppressive test) at doses of 150, 300 and 600 mg/kg suppressing the parasitemia level by 20.08%, 41.66% and 53.46% respectively, while chloroquine produced the highest parasite suppression of 85.73% at 5 mg/kg when compared to negative group. The extract also showed a dose - dependent significant (p ≤ 0.05) decrease in parasitemia level at 150, 300 and 600 mg/kg in established infection (curative test) producing a chemo-suppression at 46.20%, 36.62% and 8.25% respectively with chloroquine producing the highest chemo-suppression of 73.24% at 5 mg/kg when compared to the negative control. The findings of this study suggest that the root bark extract of the plant is active against the malaria parasite used and this is consistent with the ethnomedicinal use of Annona senegalensis in the treatment of malaria.

Keywords: Malaria, Parasite, Root Bark, Extract, Annona senegalensis, Phytochemistry