Structure-activity relationship of walnut peptide in gastrointestinal digestion, absorption and antioxidant activity

The structure-activity relationship between digestion of walnut peptide (<3 kDa) and antioxidant activity were explored, and the inhibitory effect of DPP-IV on antioxidant peptide KGHLFPN (Lys-Gly-His-Leu-Phe-Pro-Asn) was selected. After simulated gastrointestinal digestion, the peptides’ antioxidant capacities were enhanced, tertiary structures were weaker, and secondary structures were random coiled. After the digestion, the peptide and C–H phylyl bonds were broken and macromolecular proteins were hydrolyzed. Antioxidant walnut peptide KGHLFPN was a good DPP-IV inhibitor. And 4–8 h may be the optimal time for oral absorption of KGHLFPN in vivo. Therefore, walnut protein hydrolysate (<3 kDa) can be used as an antioxidant precursor, and walnut peptides can be potential food-derived antioxidants.