The protective effect of silymarin on the carbon tetrachloride (CCl4)-induced liver injury in common carp (Cyprinus carpio)

Silymarin, a mixture of bioactive flavonolignans from the milk thistle (Silybum marianum), is traditionally used in herbal medicine to defend against various hepatotoxic agents. The aim of the present study was to evaluate the protective effect of silymarin against carbon tetrachloride (CCl4)-induced liver injury in fish. Common carp, with an average initial weight of 17.0 +/- 1.1 g, were fed diet containing four doses of silymarin (0, 0.1, 0.5, and 1 g/kg diet) for 60 d. Fish were then given an intraperitoneal injection of CCl4 (30% in arachis oil) at a dose of 0.5 ml/kg body weight. At 72 h after CCl4 injection, blood and liver samples were collected for the analyses of serum biochemical parameters, liver index, peroxidation product, glutathione, and antioxidant enzyme activities. The results showed that administration of silymarin at 0.5 and 1 g/kg diet for 60 d prior to CCl4 intoxication significantly reduced the elevated activities of glutamate pyruvate transaminase, glutamate oxalate transaminase, lactate dehydrogenase (LDH), and increased the reduced levels of total protein and albumin in the serum. The reduced levels of liver index, superoxide dismutase, glutathione peroxidase, catalase, glutathione, and total antioxidant capacity were markedly increased, and malondialdehyde formation was significantly restrained in the liver. However, these parameters, except LDH, were not significantly changed in fish fed with silymarin at 0.1 g/kg diet. Based on the results, it can be concluded that silymarin has protective effect against CCl4-induced hepatotoxicity in fish. It is suggested that silymarin may be used as a hepatoprotective agent to prevent liver diseases in fish.