ENHANCED VASODILATORY POTENCY OF WHEY-DERIVED PEPTIDES GENERATED BY SIMULATED GASTROINTESTINAL DIGESTION

Whey proteins present high nutritional value and encrypted biofunctional peptides which need to be released from the parent protein through enzymatic hydrolysis or during gastrointestinal digestion. Among bioactive peptides, the antihypertensives are the most studied, which is related to the high prevalence of this chronic disease. The present study investigated whether the molecular changes occurred during the simulated gastrointestinal digestion of a whey protein hydrolysate produced in pilot scale could modulate its vasorelaxant potential in rat aortic rings. A whey protein concentrate 88% was suspended (1.25% w/v) and it was hydrolyzed by pepsin for 3h (pH2, 37°C). Then, pepsin was inactivated (80°C/5min) and the hydrolysate was spray dried. A whey hydrolysate solution (8% w/v) was submitted to a simulated gastrointestinal digestion and samples were chemically and biologically evaluated. The release of NH2 groups ranged from 12.4 mg.g-1 to 24.2 mg.g-1, with a small degree of hydrolysis achieved during the gastric phase and a more intense intestinal proteolysis. A complete β-lactoglobulin hydrolysis was observed on the electrophoresis gel after 10min of intestinal digestion. RP-HPLC peptide profiles revealed the hydrolyses of the main whey proteins and the formation of a wide peptide profile. These molecules were sequenced by Nano-RSLC-MS/MS and 198 peptides were generated during the in vitro digestion. The concentration-response curve of the endothelium-dependent vasorelaxation in rat aortic rings was recorded and showed that digestion enhanced the vasodilatory effect of the peptides in 90 times-fold, achieving 84.6%, but it was completely ineffective in endothelium-intact preparations, different from the undigested sample. Furthermore, the half maximal effective concentration for the vasodilatory effect reduced from 5017 (4740-5270) µg.mL-1, for the undigested to 1.07 (0.75-1.51) µg.mL-1, for the digested hydrolysate. Molecular changes occurred during digestion resulted in alterations in the mechanisms of action and in an enhancement in the vasodilatory effect of the whey peptides.