Antioxidant activity and hepatoprotective effect of a polysaccharide from Bei Chaihu (Bupleurum chinense DC)

Chinese medicine plays a pivotal role in hepatoprotective treatment. In the present study, a water-soluble polysaccharide fraction (WBCP) was fractioned from the roots of Bupleurum chinense and purified by DEAE-cellulose and Surperdex 200 HR chromatography. The physicochemical properties, antioxidative and hepatoprotective activities of WBCP were evaluated in a rat model of hepatic injury caused by d-galactosamine (GalN). Hepatoprotective effect was evaluated by measuring aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) activities in the plasma of mice. Antioxidant activity was evaluated by measuring biochemical parameters in the mouse liver homogenate, such as glutathione reductase (GR), γ-glutamylcysteine synthetase (GCS), glutathione S-transferase (GST) and superoxide dismutase (SOD) activities, as well as glutathione (GSH) and thiobarbituric acid reactive substances (TBARS) levels. The results showed the oral administration of WBCP could significantly reduce the activity of AST, ALT, ALP and LDH, indicating that WBCP possesses hepatoprotective activity. Furthermore, there was general a statistically significant increase in the activities of GSH, GR, GCS, GST and SOD, and a loss in TBARS in the liver of WBCP-treated group compared with the control group. In addition, the elevated levels of pro-inflammatory cytokine tumour necrosis factor-alpha (TNF-α) in the serum of the experimental animals was significantly returned by WBCP treatment at the dose of 400 mg/kg. These results clearly demonstrated that WBCP possess promising hepatoprotective effects against GalN-induced liver damage, which may be mediated through augmentation of antioxidant defenses.