Preparation and evaluation of an antioxidant peptide from collagen hydrolysate of skipjack tuna fishbone

In the current research,acid soluble collagen(ASC)from skipjack tuna(Katsuwonus pelamis)fishbone was successfully isolated with the yield of 2.47%(dry weight basis).The antioxidant hydrolysate of ASC(TFCH)was prepared through a two-stage in vitro digestion(3-h pepsin followed by 3-h trypsin),and one new antioxidant peptide(TFCH-P2)was further isolated from TFCH using ultrafiltration,gel chromatography,and RP-HPLC.The amino acid sequence of TFCH-P2 was identified as Gly-Pro-Ala-Gly-Pro-Ala-Gly-Glu-Gln-Gly(GPAGPAGQEG)with molecular weight of 839.87 u(M+H⁺ 840.68 u).TFCH-P2 exhibited good scavenging activity on DPPH radical,hydroxyl radical,ABTS radical and superoxide anion radical with EC₅₀ of 0.18,0.97,0.52 and 0.38 mg/mL,respectively.TFCH-P2 was also effectively against lipid peroxidation in a linoleic acid model system.The antioxidant activity of TFCH-P2 was due to the presence of hydrophobic amino acid residues within the peptide sequence.The result suggested that TFCH-P2 could be used as natural antioxidant in enhancing antioxidant properties of functional foods and in preventing oxidation reactions in food processing.