Identification of potential antioxidant peptides from protein hydrolysates of pearl oil apricot almonds: Combination of in vitro and molecular docking studies

Pearl oil apricot almonds are rich in proteins, being a valuable raw material for preparing antioxidant peptides. In this study, almond protein hydrolysates (APHs) were obtained by enzymatic hydrolysis and divided into APHs-1 (<3 kDa), APHs-2 (3-10 kDa), and APHs-3 (>10 kDa). APHs-1-c, purified from APHs-1, was proved to show the strongest antioxidant effect through activity tracking experiments. APHs-1-c also can protect HepG2 cells against oxidative damage by reducing intracellular reactive oxygen species and MDA levels, elevating glutathione levels as well as increasing superoxide dismutase and catalase activities, and its protective effect is related to the Keap1-Nrf2 signaling pathway. Forty bioactive peptide sequences were identified from APHs-1-c, and Thr-Glu-Asp-Asp-Trp-Arg-Trp-His (TEDDWRWH; P1), Trp-Tyr-Asp-Asn-Glu-Trp-Gly-Tyr-Arg (WYDNEWGYR; P2), and Ala-Glu-Asp-His-Glu-Trp-Trp-Arg (AEDHEWWWR; P3) had the most potential for antioxidant activity by molecular docking studies. P1, P2, and P3 showed desirable 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity (IC50 = 0.634-3.381 mmol/L), 2,2 & PRIME;-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical scavenging activity (IC50 = 0.221-0.309 mmol/L), and ferric-reducing antioxidant power. These results suggested that almonds protein hydrolysates and its derived antioxidant peptides could serve as potential ingredients applied in functional foods.