Amelioration of the Lipogenesis, Oxidative Stress and Apoptosis of Hepatocytes by a Novel Proteoglycan from Ganoderma lucidum

The steatosis and resultant oxidative stress and apoptosis play the important roles in the progression of nonalcoholic fatty liver disease (NAFLD), therefore, searching for the effective drugs against NAFLD has been a hot topic. In this work, we investigated a hyperbranched proteoglycan, namely FYGL extracted from Ganoderma lucidum, inhibiting the palmitic acid (PA)-induced steatosis in HepG2 hepatocytes. FYGL compose of hydrophilic polysaccharide and lipophilic protein. Both moieties conclude the reductive residues, such as glucose and cystine, making FYGL capable of anti-oxidation. Herein, we demonstrated that FYGL can significantly inhibit the steatosis, i.e., decrease the contents of triglycerides (TG) and total cholesterol (TC) in hepatic cells on the mechanism of increasing the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC), therefore inhibiting the expressions of sterol regulatory element-binding protein 1 (SREBP1) and fatty acid synthase (FASN), furthermore leading to the carnitine palmitoyl transferase-1 (CPT-1) expression increased against steatosis induced by fatty acids oxidation. Meanwhile, FYGL can alleviate reactive oxygen species (ROS) and malondialdehyde (MDA), promote superoxide dismutase (SOD) and total antioxidant capacity (T-AOC). Moreover, FYGL can prevent the cells from apoptosis by regulating the apoptosis-related protein expressions and alleviating oxidative stress. Notably, FYGL could significantly recover the cells activity and inhibit lactate dehydrogenase (LDH) release which were negatively induced by high concentration PA. These results demonstrated that FYGL has the potential functions to prevent the hepatocytes from lipid accumulation, oxidative stress and apoptosis, therefore against NAFLD.