A novel antioxidant peptide purified from defatted round scad (Decapterus maruadsi) protein hydrolysate extends lifespan in Caenorhabditis elegans

The residue rich in protein (up to 88.78%) obtained from round scad (Decapterus maruadsi) after oil extraction, was hydrolyzed by Alcalase to produce antioxidative peptides. The hydrolysate was separated by ultrafiltration, Sephadex G-15 and RP-HPLC, and the active fractions were screened by 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethylbenzothiazoline-6 sulphonic acid) diammonium salt (ABTS), reducing power and oxygen radical absorbance capacity (ORAC). The obtained peptide with the highest antioxidative activity was then analyzed by HPLC and LC-MS/MS and its anti-aging effect was examined using Caenorhabditis elegans (C. elegans) model. The peptide (Ile-Leu-Gly-Ala-Thr-Ile-Asp-Asn-Ser-Lys, 1153.4 Da), identified by LC-MS/MS showed the highest antioxidant activity. C. elegans fed with the selected peptide had longer lifespan, higher survival rate, superoxide dismutase (SOD) and catalase (CAT) activities than the control group (P<0.05), demonstrating the promising anti-aging effects of the antioxidant peptide from defatted round scad.