Separation, enrichment and cytoprotection of antioxidant peptides from Xuanwei ham using aqueous two-phase extraction

In this study, an ethanol/(NH4)2SO4 biphasic system (aqueous two-phase system) was designed for effectively separating antioxidant peptides from Xuanwei ham. Through optimization using single factor experiments and response surface methodology, it was determined that under the conditions of a 20 % ethanol aqueous solution (w/w), 25.5 % (NH4)2SO4 aqueous solution (w/w), and a pH of 8.80, the optimal extraction rate was 59.0 ± 1.73 %. In vitro antioxidant activity and cellular assays showed that the top-phase purified peptide exhibited a strong antioxidant activity, and it improved the viability of HaCat cells damaged by ultraviolet A irradiation, where the cell viability increased from 56.14 ± 1.05 % to 66.3 ± 1.76 %. We used an in silico strategy to screen the peptides in order to identify those with potential antioxidant activity and finally obtained 10 new peptides, which emphasize the important role of amino acids Pro, Gly, and Ala in their antioxidant activity.