Identification and characterization of antioxidative peptides derived from simulated in vitro gastrointestinal digestion of walnut meal proteins

The aim of this study was to isolate and identify antioxidant peptides from defatted walnut meal proteins hydrolysates (DWMPH) prepared by simulated gastrointestinal digestion, and to evaluate the protective effect of the selected antioxidant peptides against oxidative damage to SH-SY5Y cells. The DWMPH were purified by ultrafiltration, gel filtration chromatography and RP-HPLC successively, and finally six major peptides were identified as VRN, NPAN, AHSVGP, SSE, TY and SGGY by UPLC-QTOF-MS. TY and SGGY displayed stronger ABTS radical scavenging activity and higher ORAC value in comparison with other four peptides. Furthermore, 0.5 mg/mL SGGY exhibited significantly protective effect on SH-SY5Y cells against oxidative damage (p < .01). Therefore, it was suggested that walnut meal protein could serve as a potential source of antioxidative peptides through gastrointestinal digestion.