Protective Effects of Methanol Extract of Perilla Seed Meal against Oxidative Stress in HepG2 Cells

This study aimed to evaluate the protective effect of methanol extract of perilla seed meal (PSE) against oxidative stress induced by tert-butylhydroperoxide (t-BHP) in HepG2 cells. The total phenolics and flavonoid contents of PSE were 41.36 1.00 mg gallic acid equivalents/g of residue and 38.20 0.17 mg catechin equivalents/g of residue, respectively. Quantitative analysis of the major constituent phenolic acids and tocopherols was achieved by using high-performance liquid chromatography. PSE (10-100 pg/mL) pretreatment significantly prevented t-BHP-induced cytotoxicity in HepG2 cells. Oxidative damage induced by t-BHP was accompanied by glutathione depletion, ROS generation, and lipid peroxidation, which were all significantly ameliorated by PSE. The cytoprotective effect of PSE was attributed to the modulation of cellular antioxidant defense enzymes such as glutathione peroxidase, superoxide dismutase, glutathione reductase, and catalase. Collectively, the bioactive compounds of PSE were able to prevent oxidative stress through the enhancement of the antioxidant indices.