Effects of bioactive peptides encrypted in whey-, soy- and rice protein on local and systemic angiotensin-converting enzyme activity

The renin-angiotensin system (RAS) is one of the main control systems of arterial blood pressure. Here, key player is the angiotensin converting enzyme (ACE). Inhibition of ACE is a standard therapy to lower elevated blood pressure. This study aimed to determine the ACE-inhibitory activity of tryptophan- and tyrosine-containing peptide mixes, based on hydrolysates of whey-, soy- and rice-protein. Effects on circulating and tissue ACE were investigated. IC50 values range from 16.60 +/- 2.59 mg/I to 282.04 +/- 18.51 mg/1, depending on the peptide mix and the ACE-system. Strongest ACE-inhibition is generally obtained with whey peptide mix characterized by a high fraction of isoleucine-tryptophan. Good inhibitory potential was obtained for plasma and tissue ACE. Thus, the use of whey peptide mix and isoleucinetryptophan, respectively, appears to deserve further studies as innovative food additives with the potential to delay or even prevent RAS-related hypertension and subsequent deterioration of vessel structure and function. (C) 2016 Elsevier Ltd. All rights reserved.