Improving effect of domestic walnut (Juglans regia) extract on high glucose- and oleic acid-induced non-alcoholic fatty liver disease in HepG2 cells

Abstract

This study was investigated to evaluate the in vitro anti-diabetic activity and lipid accumulation inhibitory effect of the domestic walnut (Junglans regia, Gimcheon 1ho cultivar) in high glucose- and oleic acid-induced hepatic HepG2 cells. Eighty percent of ethanolic extract from Gimcheon 1ho (GC) showed higher inhibitory effects against α-amylase and α-glucosidase activities when compared to other ethanolic extracts. GC significantly inhibited the formation of advanced glycation end products (AGEs). The GC increased cell viability against H2O2- and high glucose-induced cell death determined by 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. GC reduced the formation of reactive oxygen species (ROS) in H2O2- and high glucose-induced HepG2 cells determined by 2’,7’-dichlorofluorescein diacetate (DCF-DA) assay. GC inhibited lipid accumulation in the oleic acid-induced HepG2 cells. The GC increased AMP-activated protein kinase (AMPK) phosphorylation and decreased the expression of lipid metabolism related proteins such as sterol regulatory element-binding proteins 1 (SREBP-1), fatty acid synthase (FAS), sterol regulatory element-binding protein 2 (SREBP-2) and 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMGCR). The results suggest GC is a potentially functional food material which can improve nonalcoholic fatty liver disease by inhibiting lipid accumulation.