Preparation and identification of antioxidant peptides from protein hydrolysate of skate (Raja porosa) cartilage

In the experiment, three bioactive hexapeptides were isolated from the protein hydrolysate of skate (Raja porosa) cartilage using ultrafiltration and chromatographic methods, and their amino acid sequences were identified as Phe-Ile-Met-Gly-Pro-Tyr (FIMGPY, RCP-I), Gly-Pro-Ala-Gly-Asp-Tyr (GPAGDY, RCP-II) and Ile-Val-Ala-Gly-Pro-Gln (IVAGPQ, RCP-III) with molecular weights of 726.90, 578.58 and 583.69 Da, respectively. RCP-I, RCP-II and RCP-III exhibited good scavenging activities on DPPH
- (EC50 3.5768, 6.0147 and 6.733 M), HO
- (EC50 4.1821, 6.7752 and 8.6176 M), O 2
- − (EC50 2.2149, 2.8691 and 3.1181 M) and ABTS
- + (EC50 1.4307, 1.3308 and 2.2101 M), respectively. RCP-III was also effective against lipid peroxidation in a linoleic acid model system. The antioxidant activities of isolated peptides were due to their small molecular structures and presence of antioxidant and hydrophobic amino acid residues in their sequences. The result suggested that the isolated peptides have excellent antioxidant properties and might be applied as food additives and functional foods.