ABSTRACT
This study was conducted to identify and characterize antioxidant peptides from the alcalase hydrolysate of the blue-spotted stingray. Purification steps guided by ABTS cation radical (ABTS+) scavenging assay and de novo peptide sequencing produced two peptides, WAFAPA (661.3224â¯Da) and MYPGLA (650.3098â¯Da). WAFAPA (EC50â¯=â¯12.6⯵M) had stronger antioxidant activity than glutathione (EC50â¯=â¯13.7⯵M) and MYPGLA (EC50â¯=â¯19.8⯵M). Synergism between WAFAPA and MYPGLA was detected. WAFAPA and MYPGLA surpassed carnosine in their ability to suppress H2O2-induced lipid oxidation. The peptides protected plasmid DNA and proteins from Fenton's reagent-induced oxidative damage. Thermal (25-100⯰C) and pH 3-11 treatments did not alter antioxidant activity of the peptides. MYPGLA maintained its antioxidant activity after simulated gastrointestinal digestion, whereas WAFAPA showed a partial loss. The two peptides may have potential applications as functional food ingredients or nutraceuticals, whether used singly or in combination.