Phytochemicals, Antioxidative and in vivo Hepatoprotective Potentials of Litsea floribunda (BL.) Gamble (Lauraceae) - An Endemic Tree Species of the Southern Western Ghats, India

The leaf and stem bark samples of Litsea floribunda (Bl.) Gamble a medicinal tree species, endemic to the Western Ghats, a biodiversity ‘hot spot’ of India were subjected to soxhlet extraction, phytochemical analysis and antioxidant activity by employing in vitro screening methods. The extracts exhibiting high antioxidant activity were assessed for the hepatoprotective activity against paracetamol-induced liver damage in rats. Phytochemical analysis of the stem bark and leaf extracts indicated the presence of flavonoids, terpenoids, cardiac glycosides, tannins, saponins and reducing sugars in the hexane, chloroform, ethyl acetate, absolute ethanol, methanol and aqueous extracts, respectively. The in vitro antioxidant activities revealed that the absolute ethanol and the aqueous extracts of stem bark as well as leaves exhibited high activity. The aqueous (98.9± 0.7 mg/g GAE), and absolute ethanol extracts (114.8±0.2 mg/ g GAE) of leaf as well as the stem bark aqueous (112.4±0.7 mg/g GAE) and absolute ethanol extracts (117.4±0.1 mg/g GAE) extracts contained higher amount of total phenolics compared to other solvent extracts. On the basis of the IC_50 values (21.5±0.8 μg/ml to 29.0±0.2 μg/ml), the leaf/stem bark absolute ethanol and the aqueous extracts were considered for hepatoprotective studies in the in vivo rat model. The absolute ethanol and aqueous leaf and stem bark extracts were administered orally to 11 groups of animals in two doses (250 and 500 mg/kg b.w) with hepatotoxicity induced by paracetamol (2 mg/kg b.w.). Silymarin (100 mg/kg b.w.), the standard drug was used as a positive control. The stem bark aqueous and absolute ethanol extracts were effective in protecting the liver against the toxicity induced by paracetamol in rats. This was evident from the significant reduction in serum enzymes such as Serum Glutamic Pyruvate Transaminase (SGPT), Serum Glutamic Oxaloacetate Transaminase (SGOT), alkaline phosphatase (ALP), serum bilirubin, serum total proteins and liver weight against the treated group of animals. Histopathological studies conducted by sectioning of liver samples also indicated the hepatoprotective nature of the stem bark absolute ethanol and aqueous extracts with moderately dilated hepatic vein and degenerated peripheral hepatocyte infiltration suggestive of reduced toxicity. The results obtained strongly indicate that the absolute ethanolic and aqueous extracts of L. floribunda stem bark has good antioxidant activity