Protective effect of Rabdosia amethystoides (Benth) Hara extract on acute liver injury induced by Concanavalin A in mice through inhibition of TLR4-NF-κB signaling pathway.

Extract of Rabdosia amethystoides (Benth) Hara (ERA), a traditional Chinese medicine has antibacterial, antiviral, anti-tumor, anti-hepatitis and anti-inflammatory properties. However, the hepatoprotective effects and molecular mechanisms of ERA on acute liver injury have not been fully elucidated. This study aims to investigate the anti-inflammatory effect and liver protection of ERA against the acute liver injury induced by Concanavalin A (Con A) and its underlying molecular mechanisms in mice. Mice received ERA (50, 100, 150 mg/kg body weight) by gavage before Con A intravenous administration. We found that ERA pretreatment was able to significantly reduce the elevated serum alanine and aspartate aminotransferase levels and liver necrosis in Con A-induced hepatitis. In addition, ERA treatment significantly decreased the myeloperoxidase, malondialdehyde levels and augmented superoxide dismutase level in the liver tissue, and also suppressed the secretion of proinflammatory cytokines in the serum, compared with Con A group by enzyme linked immunosorbent assay. Furthermore, we observed that ERA pretreatment can significantly decrease the expression level of Toll-like receptor (TLR) 4 mRNA or protein in liver tissues. Further results showed that ERA pretreatment was capable of attenuating the activation of the NF-κB pathway by inhibiting IκBα kinase and p65 phosphorylation in Con A-induced liver injury. Our results demonstrate that ERA pretreatment has hepatoprotective property against Con A-induced liver injury through inhibition of inflammatory mediators in mice. The beneficial effect of ERA may be mediated by the downregulation of TLR4 expression and the inhibition of NF-κB activation.