Identification of bioactive peptides from brewers' spent grain and contribution of Leu/Ile to bioactive potency

Brewer's spent grain (BSG) is a co-product of the brewing industry and is a potentially rich source of bioactive peptides. A BSG protein hydrolysate, manufactured at a semi-pilot scale, mediated significant hypotensive effects 6 h after ingestion in spontaneously hypertensive rats. This hydrolysate was fractionated and further analysed by UPLC-ESI-MS/MS for peptide identification. The peptides, IPY and LPY demonstrated the highest antioxidant activity (0.37 +/- 0.02 and 0.34 +/- 0.02 mu mol Trolox equivalents mu M peptide(-1), respectively), IPLQP and LPLQP had the highest ACE inhibitory activity (IC50: 3.10 +/- 0.60 and 3.17 +/- 0.60 mu M, respectively) while IPVP had the highest DPP-IV inhibitory activity (IC50: 38.67 +/- 5.94 mu M). Overall, peptides containing I had higher in vitro bioactivities when compared to peptides having L. Novel BSG peptides were identified with potential for application as naturally derived ingredients for the management of cardiovascular disease and type 2 diabetes.