Bioactive peptides from Atlantic salmon (Salmo salar) with angiotensin converting enzyme and dipeptidyl peptidase IV inhibitory, and antioxidant activities

•Protein extraction from salmon trimmings was optimized giving a yield of 93% (w/w).•Protein hydrolysates displayed good DPP-IV and ACE inhibitory, and antioxidant activity.•The hydrolysates retained activity following simulated in vitro gastrointestinal digestion.•Novel peptides with DPP-IV and ACE inhibitory, and ORAC activities were identified.

The pH shift method was utilised for the recovery of proteins from salmon trimmings (ST), yielding 93% (w/w) protein. ST protein (STP) hydrolysates were generated with different enzyme preparations. STP incubated with Corolase PP for 1 h (STP-C1) had the most potent angiotensin converting enzyme (ACE) and dipeptidyl peptidase IV (DPP-IV) inhibitory and oxygen radical absorbance capacity (ORAC) activities. Analysis of fractions of STP-C1 using UPLC-MS/MS identified sixteen peptides/amino acids. Tyr-Pro had the highest ACE inhibitory activity (ACE IC50 = 5.21 ± 0.94 μM). The highest DPP-IV inhibitory activity was found with the amino acid Tyr (DPP-IV IC50 = 75.15 ± 0.84 μM). Val-Pro had the highest ORAC activity (19.45 ± 2.15 μmol of TE g−1). To our knowledge, the peptides Gly-Pro-Ala-Val, Val-Cys, and Phe-Phe have not been previously identified to have the activities tested in this study. These results indicate that STP hydrolysates are potential sources of bioactive peptides.