Antioxidant activity of Green tea extract against Isoniazid induced hepatotoxicity in the rats

Tuberculosis continues to be a common health problem worldwide. Isoniazid, an antibiotic used routinely for tuberculosis chemotherapy is documented to be a potent hepatotoxicant. The aim of the present study was to assess the antioxidant activity of Green tea extract (GTE) against Isoniazid induced hepatotoxicity in the rats. Male Wistar rats were randomly assigned into 4 groups of 10 animals each including 1- normal healthy control rats, 2- healthy rats receiving (GTE) 3- toxicant control, and 4- toxicant drug+ GTE treatment group. In groups 2 and 4 GTE (1.5%, w/v) was given as only source of drinking for 8 weeks. In the midst stage of experiment (4th and 5th weeks), Isonizid (50 mg/kg b.w./day, i.p.) was administrated for groups 3 and 4 for a period of 2 weeks. At the end of experiment, product of lipid peroxidation (MDA), activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and glutathione reductase (GR) were assayed in liver homogenates to evaluate antioxidant activity. Significant differences among the groups were determined by one-way analysis of variance followed by Tukey post-test. Statistical significance was considered at p<0.05. In Isoniazid-treated rats, GTE (1.5%, w/v) significantly decreased the lipid peroxidation and elevated the levels of antioxidant enzymes. This study showed that the hepatoprotective effect of GTE in Isoniazd-induced oxidative damage may be related to its antioxidant and free radical scavenging activity.