Casein Glycomacropeptide Hydrolysates Exert Cytoprotective Effect against Cellular Oxidative Stress by Up-Regulating HO-1 Expression in HepG2 Cells

Oxidative stress is considered as an important mediator in the progression of metabolic disorders. The objective of this study was to investigate the potential hepatoprotective effects and mechanisms of bovine casein glycomacropeptide hydrolysates (GHP) on hydrogen peroxide (H(2)O(2))-induced oxidative damage in HepG2 cells. Results showed that GHP significantly blocked H(2)O(2)-induced intracellular reactive oxygen species (ROS) generation and cell viability reduction in a dose-dependent manner. Further, GHP concentration-dependently induced heme oxygenase-1 (HO-1) expression and increased nuclear factor-erythroid 2-related factor 2 (Nrf2) nuclear translocation. Moreover, pretreatment of GHP increased the activation of p38 mitogen-activated protein kinase (p38 MAPK) and extracellular signal-regulated protein kinase 1/2 (ERK1/2), which were shown to contribute to Nrf2-mediated HO-1 expression. Taken together, GHP protected HepG2 cells from oxidative stress by activation of Nrf2 and HO-1 via p38 MAPK and ERK1/2 signaling pathways. Our findings indicate that bovine casein glycomacropeptide hydrolysates might be a potential ingredient in the treatment of oxidative stress-related disorders and further studies are needed to investigate the protective effects in vivo.