Geniposide protected hepatocytes from acetaminophen hepatotoxicity by down-regulating CYP 2E1 expression and inhibiting TLR 4/NF-κB signaling pathway

Acetaminophen (APAP) is a widely used over-the-counter drug for antipyretic and analgesic, but an overdose will induce acute liver injury. APAP hepatotoxicity has been the most common cause of acute liver failure in western countries with high morbidity and mortality. Geniposide (GP), an iridoid glycoside extracted from the fruit of Gardenia jasminoides, has been reported to exert a profound anti-inflammatory activity on acute and chronic diseases. However, it is never demonstrated whether GP can protect hepatocytes from APAP hepatotoxicity. In this study, we investigated the protective effect and underlying mechanism of GP against AILI. The results showed that GP pretreatment reduced the levels of ALT and AST in a dose-dependent manner and alleviated hepatocyte necrosis and apoptosis in mice exposed at APAP. Moreover, it suppressed the expression of CYP 2E1 and attenuated the exhaustion of GSH and accumulation of MDA in the liver. Furthermore, GP remarkably inhibited inflammatory cells infiltration and mitigated the release of IL-1 beta and TNF-alpha, and inhibited Toll-like receptor 4 (TLR4) expression and nuclear factor kappa (NF-kappa B) activation. These data suggested that GP could effectively protect hepatocytes from APAP hepatotoxicity through the down-regulation of CYP 2E1 expression and the inhibition of TLR4/NF-kappa B signaling pathway.