Serum AST activities of rats before and after treatment with anti-tuberculosis drugs and silymarin. Constant doses of INH (50 mg/kg), RIF (100 mg/kg), PZA (350 mg/kg) and silymarin (200 mg/kg) were used. Group I: Control, Group II: Silymarin control, Group III: INH+RIF, Group IV: INH+RIF+PZA, Group V: INH+RIF+Silymarin, and Group VI: INH+RIF+PZA+Silymarin. * P < 0.001 as compared with groups I, II, V and VI. * P < 0.05 as compared with Groups I and II.