Identification of a new antioxidant peptide from porcine plasma by in vitro digestion and its cytoprotective effect on H2O2 induced HepG2 model

Antioxidant peptide, referred as Trp-Gly-Pro-Gly-Val-Glu (WGPGVE), was isolated and identified from porcine plasma which was hydrolysised 5 h by alkaline protease. The sequence of WGPGVE had hydrophobic amino acids G, V, aromatic amino acids W, and acidic amino acid E, as well as its values of hydroxyl, ABTS, DPPH radicals scavenging rates and iron chelating rate were improved by 30.15%, 10.05%, 38.69%, 51.40% respectively, compared to glutathione (29.32%, 81.06%, 25.43%, 17.82%). Moreover, under in vitro digestion model, it exhibited stable antioxidation (50.15%, 92.49%, 24.29%, 35.35%) after the hydrolysis effect of pepsin and trypsin. Additionally, WGPGVE could protect HepG2 cells against H2O2 by promoting the expression of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and decreasing reactive oxygen species (ROS), malondialdehyde (MDA) contents. Thus, the new sequence antioxidant peptide could be potentially used in pharmaceuticals or functional foods and promote the application of porcine plasma in food.