Bio-Assay Guided Identification of Antioxidant Fractions from Methanolic Extract of Polyalthia longifolia Seeds and their Hepatoprotective Effects against Ethanol Induced Oxidative Stress

The present study is aimed to evaluate the antioxidant and hepatoprotective properties of selected methanolic fractions of Polyalthia longifolia (Sonn.) Thwaite seeds in ethanol-induced oxidative stress in rats. Initially, methanolic extract of Polyalthia longifolia seeds was fractionated using column chromatography. The preliminary antioxidant screening of these fractions identified two main bioactive fractions (F3 and F5), which were found to have significant radical scavenging and metal ion chelation properties compared with ascorbic acid. Based on the antioxidant profile, F3 and F5 were evaluated for hepatoprotective activity in ethanol-intoxicated rats. The Wistar rats were grouped (n=6) and treated with F3 and F5 (200 and 400 mg/kg), ethanol (5 g/kg, 20 % w/v) and silymarin (100 mg/kg) orally for 28 d. The outcomes of the study found that chronic administration of ethanol significantly (p<0.0001) altered the liver parameters and oxidative stress markers (malondialdehyde, superoxide dismutase and catalase). The co-administration of F5 prominently ameliorated the oxidative stress induced by ethanol compared to F3. Histopathological studies further supported the significant protective action of F5. The present study demonstrates that the Polyalthia longifolia seeds possess significant antioxidant properties by augmenting the magnitude of the antioxidant enzymes superoxide dismutase and catalase and further reducing malondialdehyde levels.