Hepatoprotective and antioxidant properties of extract of Carmellia sinensis (black tea) in rats

Hepatoprotective and antioxidant effects of water extracts of black tea (Camellia sinensis) were studied in sodium oxalate treated rats. Lipid peroxidation was induced in rats by administration of 100 mg/kgbody weight sodium oxalate. The protective effect of black tea was assessed by monitoring the serum and tissue levels of malondialdehyde, catalase activity, aspartate transaminase (AST) and alaninetransaminase (ALT) as well as serum vitamin C content in the normal, control and experimental rats after 10 and 20 days of tea administration. It was observed that tea 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 bodyweight of tea extract, serum level of malondialdehyde was  reduced from 47.855±1.050 to 32.186±0.882 nm/h, AST activity from 59±2.95 to 31±1.40 IU and ALT activity from 39±2.51 to 25±1.25 IU. Moreover, administration of 200 mg/Kg body weight of tea for 10 days caused an increase in serum catalase activity from 7 to 10% and serum vitamin C level was increased from 45.39±9.75 to 79.11±5.13 mg/100ml. In the tissues, the same trend was observed. The result also indicated that prolonged tea 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)