Purification and antioxidant properties of octapeptide from salmon byproduct protein hydrolysate by gastrointestinal digestion

Pectoral fin protein from salmon processing byproduct was hydrolyzed using Alcalase, Flavourzyme, Neutrase, pepsin, Protamex, and trypsin, and the peptic hydrolysate showed the highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. Antioxidant peptide was purified using consecutive chromatography. The purified antioxidant peptide was identified to be Phe-Leu-Asn-Glu-Phe-Leu-His-Val with molecular weight of 1018.48 Da by time of flight-mass spectrometry/mass spectrometry (TOF-MS) analysis. The IC50 values against DPPH and 2,2-azino-bis(3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) cation radical scavenging activity were 486 and 152 μM, respectively, and the octapeptide showed strong ferric reducing power. In addition, the octapeptide showed significant (p < 0.05) protection ability against hydroxyl radical-induced DNA damage and hydrogen peroxide-induced hepatic damage in Chang liver cells. Taken together, the pectoral fin protein hydrolysate and/or its active peptides may be useful ingredients in functional food.