Amino Acid Composition, Antioxidant, and Cytoprotective Effect of Blue Mussel (Mytilus edulis) Hydrolysate through the Inhibition of Caspase-3 Activation in Oxidative Stress-Mediated Endothelial Cell Injury

Enhanced oxidative stress plays a central role in promoting endothelial dysfunction, leading to the development of atherosclerosis. In this study, we investigated the protective effects of the hydrolysates derived from blue mussel (Mytilus edulis) against H2O2-mediated oxidative injury in human umbilical vein endothelial cells (HUVECs). The blue mussel hydrolysates were prepared by enzymatic hydrolysis with eight proteases, and blue mussel-α-chymotrypsin hydrolysate (BMCH) showed the highest antioxidant activities in DPPH radical scavenging, ABTS+ radical scavenging, and ORAC value compared to those of the other hydrolysates. BMCH also inhibited Cu2+-mediated low density lipoprotein (LDL) oxidation. Treatment of H2O2 resulted in the decreased HUVEC viability whereas pre-treatment with BMCH increased HUVEC viability and reduced reactive oxygen species (ROS) generation. BMCH pre-treatment increased cellular antioxidant capacities, including levels of glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) against H2O2-mediated oxidative stress in HUVECs. Flow cytometry and western blot analysis revealed that BMCH pre-treatment significantly reduced H2O2-mediated HUVEC apoptosis through inhibition of caspase-3 activation. Real-time-qPCR analysis showed that BMCH down-regulated expression of p53 and caspase-3 genes, as well as decreased the bax/bcl-2 ratio. Taken together, these results indicate that BMCH may be useful as functional food ingredients for protecting endothelial dysfunction or related disease.