Trans-anethole attenuates diet-induced nonalcoholic steatohepatitis through suppressing TGF-β-mediated fibrosis

•Trans-anethole dose-dependently ameliorated liver injury in MCD diet-fed mice.•Trans-anethole significantly attenuated hepatic steatosis, inflammation and hepatic fibrosis.•Trans-anethole reduced hepatic fibrosis by inhibiting transforming growth factor-beta signaling pathway both in vivo and in vitro. Nonalcoholic Steatohepatitis (NASH) is the most severe type of non-alcoholic fatty liver disease (NAFLD) and one of the most common chronic liver diseases, leading to the increased risk of liver failure, cirrhosis and hepatocellular carcinoma. Trans-anethole was reported to have anti-inflammatory, anti-obesity and anti-diabetic activities. However, its role in NASH remains unknown. Therefore, we aimed to explore the effect of Trans-anethole on NASH. Eight-week-old C57BL/6 mice were fed on a methionine- and choline-deficient (MCD) diet for 8 weeks to induce NASH in mice, and on the meanwhile, mice were also orally administrated with or without 100 mg/kg Trans-anethole daily to evaluate the effect of Trans-anethole on NASH. Trans-anethole dose-dependently ameliorated liver injury in MCD diet-fed mice, then the most effective dose of Trans-anethole 100 mg/kg was chosen. Trans-anethole significantly attenuated hepatic steatosis, inflammation and hepatic fibrosis in MCD diet-induced NASH mice. Moreover, Trans-anethole reduced hepatic fibrosis by inhibiting transforming growth factor-beta signaling pathway both in vivo and in vitro. Trans-anethole effectively ameliorated NASH in MCD diet-fed mice, which suggested that Trans-anethole might serve as a therapeutic strategy for NASH.