Dipeptidyl peptidase-IV inhibitory peptides generated by tryptic hydrolysis of a whey protein concentrate rich in β-lactoglobulin

Dipeptidyl peptidase-IV (DPP-IV) is a serine protease involved in the degradation and inactivation of incretin hormones that act by stimulating glucose-dependent insulin secretion after meal ingestion. DPP-IV inhibitors have emerged as new and promising oral agents for the treatment of type 2 diabetes. The purpose of this study was to investigate the potential of beta-lactoglobulin as natural source of DPP-IV inhibitory peptides. A whey protein concentrate rich in beta-lactoglobulin was hydrolysed with trypsin and fractionated using a chromatographic separation at semipreparative scale. Two of the six collected fractions showed notable DPP-IV inhibitory activity. These fractions were analysed by HPLC coupled to tandem mass spectrometry (HPLC-MS/MS) to identify peptides responsible for the observed activity. The most potent fragment (IPAVF) corresponded to beta-lactoglobulin f(78-82) which IC50 value was 44.7 mu M. The results suggest that peptides derived from beta-lactoglobulin would be beneficial ingredients of foods against type 2 diabetes. (C) 2013 Elsevier Ltd. All rights reserved.