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

Abstract

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 (IC50) value of 647.02 ± 4.30 µM. Leu-Leu-Asp-Leu-Gly-Val-Pro showed the highest ACE inhibitory activity with an IC50 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 IC50 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.