Abstract:In order to investigate the antioxidant activity and structure-activity relationship of casein-derived heptapeptide AVPYPQR in different systems, the antioxidant activity of AVPYPQR and its related fragments PYPQ, PYPQR, VPYPQ, VPYPQR and AVPYPQ were compared in this study using in vitro chemical assays and cellular models. The results showed that the six peptides exhibited higher ABTS free radical scavenging activity and oxygen radical absorbance capacity (ORAC) than the standard antioxidant, Trolox. The co-occurrence of Val, Ala and Arg residues led to a reduced ABTS radical scavenging activity of AVPYPQR, while the presence of Arg residue resulted in an enhanced ORAC. In the cell oxidative damage model, all the six peptides offered protection against AAPH-induced erythrocyte hemolysis. Among which, AVPYPQR exhibited the greatest protective effect, and the presence of Ala and Arg residues improved further such an effect. In H2O2-induced HepG2 cell oxidative damage model, all the peptides showed (p < 0.05) significant protective effect except for PYPQ, and the Ala, Val and Arg residues could enhance the protection but without an addictive effect. In summary, all the peptides, except for PYPQ, had strong antioxidant activity in both in vitro chemical assays and cellular models, but no significant correlation was found among the detected activities in different assays. The influence of Val, Ala and Arg residues on the antioxidant activity of AVPYPQR varied between analysis assays.
