Purification and identification of dipeptidyl peptidase IV and angiotensin-converting enzyme inhibitory peptides from silver carp (Hypophthalmichthys molitrix) muscle hydrolysate

Diabetes and hypertension are increasing threats to human health, which could be improved by inhibiting dipeptidyl peptidase IV (DPP-IV) and angiotensin-converting enzyme (ACE), respectively. Herein, we used five different enzymes to hydrolyze silver carp ( Hypophthalmichthys molitrix ) muscle protein. Among all treatments, the Neutrase-generated hydrolysate that was purified by a three-step isolation and then was identified using liquid chromatography–tandem mass spectrometry resulted in the most potent DPP-IV inhibitory activity and relatively high ACE inhibitory activity. The identified peptide Ala-Ala-Leu-Glu-Gln-Thr-Glu-Arg was the most effective at inhibiting DPP-IV with a half-maximal inhibitory concentration (IC 50 ) value of 647.02 ± 4.30 µM. Leu-Leu-Asp-Leu-Gly-Val-Pro showed the highest ACE inhibitory activity with an IC 50 value of 329.33 ± 15.53 µM. Lys-Ala-Val-Gly-Glu-Pro-Pro-Leu-Phe exhibited the dual inhibition against both DPP-IV and ACE with IC 50 values of 1,317.39 ± 20.93 µM and 726.01 ± 8.69 µM, respectively. Interestingly, it seemed that the majority of peptides which were responsible for inhibiting DPP-IV were different from the ones which caused the inhibition of ACE.