Protective effect of a polysaccharide from Anoectochilus roxburghii against carbon tetrachloride-induced acute liver injury in mice

Ethnopharmacological relevance: Anoectochilus roxburghii (Wall.) Lindl. is traditionally used for the treatment of various types of chronic and acute hepatitis in China. Considering that Anoectochilus roxburghii polysaccharide (ARPT) is the main constituent of Anoectochilus roxburghii, the present study was designed to investigate the hepatoprotective effect of ARPT and its possible mechanism in carbon tetrachloride (CCl4)induced mice. Material and methods: The hepatoprotective activity of ARPT (150, 300 and 500 mg/kg) were investigated on CCl4-induced acute liver damage in mice. The activities of alanine transaminase (ALT), aspartate transaminase (AST) were determined in serum. The hepatic levels of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) were measured in liver homogenates. The levels of cytochrome P450 sub family 2E1 (CYP2E1), tumor necrosis factor alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein-2 (MIP2), KC (Murine IL-8 ortholog), transforming growth factor-betal (TGF-beta 1), Bcl-2 and Bax were measured by quantitative real-time polymerase chain reaction (qRT-PCR). The expressions of CYP2E1, nuclear factor-kappa B (NF-kappa B) p65 and caspase-3 were evaluated by western blot assays. The hepatic levels of TNF-alpha, IL-6, MIP-2 and TGF-beta 1 were measured by enzyme-linked immunosorbent assay (ELISA). Furthermore, histopathological observation and terminal-deoxynucleoitidyl transferase mediated nick end labeling assay (TUNEL) were carried out on the separated livers of mice. Results: ARPT significantly decreased serum ALT and AST activities, hepatic MDA level, and markedly enhanced antioxidant enzyme (SOD, CAT and GSH-Px) activities and GSH level in hepatic tissue, in a dose dependent manner, when compared to the model group. Histopathological observation revealed the hepatoprotective effect of ARPT against the damage. Furthermore, ARPT remarkably inhibited CYP2E1 mRNA expression, decreased NF-kappa B p65 expression and therefore to prevent the secretion of pro-inflammatory cytokines (TNF-alpha and IL-6) and chemokines (MCP-1, MIP-2 and KC), suppressed TGF-beta 1 expression and hepatocytes apoptosis. Moreover, ARPT could prevent DNA fragmentation based on TUNEL assay results. Conclusion: These findings suggested that ARPT possessed hepatoprotective effect against CCl4-induced hepatotoxicity in mice and the action might in part be through reducing oxidative stress, inflammation and apoptosis.