Non-alcoholic fatty liver disease (NAFLD) is prevalent in the elderly population, and has symptoms ranging from liver steatosis to advanced fibrosis. Citrus peel extracts (CPEs) contain compounds that potentially improve dyslipidemia; however, the mechanism of action and effects on hepatic steatosis regulation remains unclear. Current study was aimed to investigate the protective effect of CPEs extracted through hot-air drying (CPEW) and freeze-drying (CPEF) and the underlying mechanism in a rat model of high-fat diet-induced NAFLD. The high-fat diet (HFD)-fed rats showed significant increase in total cholesterol, alanine aminotransferase (ALT), triglycerides, aspartate aminotransferase (AST), and lipid peroxidation compared to the normal chow-diet (NCD) group rats; but CPEW and CPEF limited this effect. CPEW and CPEF supplementation reduced both hepatocyte steatosis and fat accumulation involving the regulatory effect of mTORC1. Collectively, CPEW and CPEF protected deterioration of liver steatosis with AMPK activation and regulating ROS accumulation associated with interstitial disorders, which are also associated with endoplasmic reticulum (ER) redox. Thus, the application of CPEW and CPEF may lead to the development of novel therapeutic or preventive agents against NAFLD.
Keywords: AMPK; NAFLD; citrus peel; high-fat diet; mTOR-ER stress.