Angiotensin I-converting enzyme (ACE) inhibitory activity and ACE inhibitory peptides of salmon (Salmo salar) protein hydrolysates obtained by human and porcine gastrointestinal enzymes.

Małgorzata Darewicz,Piotr Minkiewicz,Anna Iwaniak,Gerd E Vegarud,Justyna Borawska

doi:10.3390/ijms150814077

Abstract

The objectives of the present study were two-fold: first, to detect whether salmon protein fractions possess angiotensin I-converting enzyme (ACE) inhibitory properties and whether salmon proteins can release ACE inhibitory peptides during a sequential in vitro hydrolysis (with commercial porcine enzymes) and ex vivo digestion (with human gastrointestinal enzymes). Secondly, to evaluate the ACE inhibitory activity of generated hydrolysates. A two-step ex vivo and in vitro model digestion was performed to simulate the human digestion process. Salmon proteins were degraded more efficiently by porcine enzymes than by human gastrointestinal juices and sarcoplasmic proteins were digested/hydrolyzed more easily than myofibrillar proteins. The ex vivo digested myofibrillar and sarcoplasmic duodenal samples showed IC50 values (concentration required to decrease the ACE activity by 50%) of 1.06 and 2.16 mg/mL, respectively. The in vitro hydrolyzed myofibrillar and sarcoplasmic samples showed IC50 values of 0.91 and 1.04 mg/mL, respectively. Based on the results of in silico studies, it was possible to identify 9 peptides of the ex vivo hydrolysates and 7 peptides of the in vitro hydrolysates of salmon proteins of 11 selected peptides. In both types of salmon hydrolysates, ACE-inhibitory peptides IW, IY, TVY and VW were identified. In the in vitro salmon protein hydrolysates an ACE-inhibitory peptides VPW and VY were also detected, while ACE-inhibitory peptides ALPHA, IVY and IWHHT were identified in the hydrolysates generated with ex vivo digestion. In our studies, we documented ACE inhibitory in vitro effects of salmon protein hydrolysates obtained by human and as well as porcine gastrointestinal enzymes.

Highlights

Bioactive peptides are inactive when they are encrypted in the parental protein but can be enzymatically released and reveal various biological activities
“hidden” peptides does not indicate a possible release of those biopeptides, we used computer software to simulate proteolysis to find angiotensin I-converting enzyme (ACE) inhibitory peptides that can potentially be generated according to the specificities of pepsin, trypsin and chymotrypsin
Human gastrointestinal enzymes generated peptides with weaker ACE inhibitory activity of the hydrolysates than the activity of peptides from hydrolysates obtained with commercial porcine enzymes

Summary

Introduction

Bioactive peptides are inactive when they are encrypted in the parental protein but can be enzymatically released and reveal various biological activities. Bioactive peptides of food origin can act as biological regulators or neurotransmitters. They may express a variety of functions in the gastrointestinal tract or in the intestinal epithelium or after systemic absorption into blood circulation [1]. ACE inhibitors are the most-studied food peptides and display different biological functions [2,3]. Fish protein hydrolysates have interested food biotechnologists due to the availability of a highly-balanced amino acid content, a high nitrogen content and the presence of biologically active peptides [5,6]. Using fish as a source of bioactive peptides provides a novel tool for the introduction of potentially high-value bioactive products

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