Hepatoprotective and antioxidant properties of methanolic extract of Piper nigrum Linn. in rats

Hepatoprotective and antioxidant effects of methanolic extracts of Piper nigrum Linn. (MPN) were studied in sodium oxalate treated rats. Lipid peroxidation was induced in rats by administration of 100 mg/kg body weight sodium oxalate. The protective effect of MPN was assessed by monitoring the serum and tissue levels of malondialdehyde, catalase activity, aspartate transaminase (AST) and alanine transaminase (ALT) as well as serum vitamin C content in the normal, control and experimental rats after 10 and 20 days of MPN administration. It was observed that MPN administration lowers significantly (p<0.05) the serum and tissue levels of malondialdehyde, as well as AST and ALT activities in a dose dependent manner. The serum level of vitamin C and activity of catalase in the serum and tissues were however shown to be significantly elevated (p<0.05). After 10 days of administration of 200 mg/kg body weight of MPN extract, serum level of malondialdehyde was reduced from 46.856±1.050 to 32.166±0.884 nm/h, AST activity from 58±2.85 to 31±1.42 IU and ALT activity from 39±2.52 to 25±1.28 IU. Moreover, administration of 200 mg/Kg body weight of MPN for 10 days caused an increase in serum catalase activity and serum vitamin C level was increased from 46.52±7.75 to 80.24±5.02 mg/100 ml. In the tissues, the same trend was observed. The result also indicated that prolonged MPN administration (for 20 days) significantly increased serum vitamin C level and the activity of catalase in both the serum, liver and the kidney (p<0.05). Also, the serum and tissue levels of malondialdehyde and transaminase activities (AST and ALT) were significantly reduced (p<0.05).