Sanggenon C alleviates palmitic acid-induced insulin resistance in HepG2 cells via AMPK pathway

Purpose: To investigate the potential role of sanggenon C alleviating in insulin resistance.Methods: HepG2 cell line was incubated with increasing concentrations of sanggenon C at 1, 5, 10, 15 or 20 μM for 4 h. to induce cytotoxicity, and then further incubated with 100 μM palmitic acid to induce insulin resistance. HepG2 cells without sanggenon C and palmitic acid treatment servered as control group. Glucose uptake was determined by measuring 2-NBDG (2-deoxy-2-[(7-nitro-2,1,3-benzoxadiazol-4-yl)-amino]-D-glucose) fluorescence intensity using a microplate reader. Oil Red O staining was used to assess intracellular lipid accumulation, while oxidative stress was evaluated by enzyme-linked immunosorbent assay (ELISA).Results: Palmitic acid significantly decreased glucose uptake and increased intracellular lipid accumulation in HepG2 (p < 0.01), while sanggenon C enhanced t glucose uptake and lowered lipid accumulation in insulin-resistant HepG2 (p < 0.01). Sanggenon C significantly attenuated palmitic acidinduced increase in p-insulin receptor substrate 1 (p-IRS1), as well as decrease in p-AKT and p-FOXO1 (p < 0.01). Palmitic acid also induced oxidative stress in HepG2 through the up-regulation of reactive oxygen species (ROS) and malondialdehyde (MDA), as well as the down-regulation of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). However, sanggenon C reduced ROS and MDA levels (p < 0.05), and enhanced SOD and GSH-Px in insulin-resistant HepG2 (p < 0.05). However, sanggenon C significantly increased p-AMP-activated protein kinase (p-AMPK) levels and p-ACC (acetyl-CoA carboxylase) in insulin-resistant HepG2 (p < 0.01).Conclusion: Sanggenon C lowers oxidative stress and ameliorates lipid accumulation thereby alleviating palmitic acid-induced insulin-resistant HepG2 cells via activation of AMPK pathway, thus suggesting that it is a potential strategy for overcoming insulin resistance.