Abstract: The objective of this study was to evaluate the preventive effect of betulinic acid (BA) on cyclophosphamide (CYP)-induced liver injury in mice. Fifty male healthy Kunming mice were randomly divided into 5 groups including control, CYP, and low-, medium- and high-dose BA groups. The mice from the control and CYP groups were administered orally with 1% starch solution, and those from the other groups with BA at doses of 0.25, 0.50 and 1.00 mg/kg mb for 14 days. Afterwards liver injury was induced by intraperitoneal injection of CYP at a dose of 50 mg/kg mb for 2 days for all groups except the control group, which was injected with physiological saline solution. The activities of aspartate transaminase (AST) and alanine aminotransferase (ALT) in the serum, the levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), glutathione (GSH) and malondialdehyde (MDA) in the liver, and the mRNA expression of pro-inflammatory cytokines interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and (IL-1β) and anti-inflammatory cytokine (IL-10) in liver were determined. The results showed as follows: 1) Pretreatment with BA increased the body mass of mice significantly at a dose of 0.50 mg/kg mb (P < 0.05), reduced the liver index significantly at 0.50 and 1.00 mg/kg mb (P < 0.05) when compared with the CYP group. 2) BA pretreatment decreased the activity of AST in a dose-dependent manner, and the effect showed a significant difference (P < 0.05) at 0.50 and 1.00 mg/kg mb. 3) Pretreatment with BA decreased hepatic vacuole degeneration caused by CYP. 4) BA reduced the activity of hepatic SOD (P < 0.05) significantly at 0.25 mg/kg mb, but had no effects on the levels of GSH-Px, CAT, GSH and MDA (P > 0.05) in the liver. 5) BA pretreatment at 0.25 and 1.00 mg/kg mb attenuated the CYP-induced increase in the mRNA expression of IL-1β (P < 0.05, P < 0.01), and significantly increased the mRNA expression of IL-6 and IL-10 (P < 0.01). At the same time, BA decreased the mRNA expression of TNF-α in the liver at 0.50 and 1.00 mg/kg mb (P < 0.01), but increased it at 0.25 mg/kg mb. Therefore, BA has a preventive effect against CYP-induced hepatic damage in mice via inhibiting the activity of antioxidant enzymes in the serum, decreasing lipid peroxidation in the liver, inhibiting the secretion of pro-inflammatory cytokines, and promoting the secretion of anti-inflammatory cytokines.

Key words: betulinic acid; cyclophosphamide; oxidative stress; anti-inflammatory; liver injury