Phytochemical and hepatotoxicity studies on Adansonia digitata leaf extracts
Adansonia digitata (Bombacaceae) leaves are used in the treatment of kidney and bladder diseases in ethno-medicine. This research was aimed at justifying its use by isolating the secondary plant metabolites responsible for the observed hepatoprotective activity. Coumarin, terpenoids and steroids were the phytochemicals found in hexane, ethyl acetate and butanol soluble fractions of the crude ethanolic extract of A. digitata leaves. These compounds were isolated by chromatographic technique and their chemical structures were identified by direct comparison of their spectroscopic data with those reported in literature. Stigmasterol, friedelin, scopoletin, β–sitosterol and β–sitosterol-3-O-β-D-glucopyranoside were isolated, identified and characterized by their UV, IR, 1H and 13C-NMR. β – sitosterol-3-O- β-D-glucopyranoside, though a known phytosterol is reported newly in the leaves of A. digitata from Nigeria. The UV and IR of four yet to be identified compounds are also reported. Only the ethylacetate soluble fraction of the crude ethanolic extract of A. digatata leaves was subjected to hepatoprotective activity against carbon tetrachloride – induced liver damage in rats and it showed significant hepatoprotective activity by reducing elevated alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphate (ALP) and lactate dehydrogenase (LDH) levels at a dose of 100 mg/kg and 200 mg/kg body weight (p<0.05). Extract at 100 mg/kg body weight showed better hepatoprotective influence than at 200 mg/kg body weight. Reduction in the effect of toxic carbon tetrachloride by the extract was further supported by histopathological results from liver samples which showed regeneration of hepatocytes.