Isolation of peptides from a novel brewers spent grain protein isolate with potential to modulate glycaemic response. (24th November 2016)

• Record Type: Journal Article
• Authors: Connolly, Alan; O'Keeffe, Martina B.; Nongonierma, Alice B.; Piggott, Charles O.; FitzGerald, Richard J.
• Is Part Of: International journal of food science & technology. Volume 52:Number 1(2017)
• Page Start: 146
• Page End: 153
• Publication Date: 2016-11-24
• Subjects: Barley -- bioactive peptides -- brewers' spent grain (BSG) protein -- DPP‐IV inhibition -- fractionation -- simulated gastrointestinal digestion; Food industry and trade -- Periodicals; 664
• DOI: 10.1111/ijfs.13260
• Languages: English
• ISSNs: 0950-5423

Abstract

Summary: The in vitro dipeptidyl peptidase‐IV (DPP‐IV) inhibitory activity of a Brewers' spent grain protein‐enriched isolate (BSG‐PI) Alcalase™ hydrolysate (AlcH), which had previously been identified as a relatively potent angiotensin‐converting enzyme (ACE) inhibitor, was determined. The half maximal DPP‐IV inhibitory concentration (IC50 ) value of AlcH following 240‐min digestion was 3.57 ± 0.19 mg mL −1 . Ultrafiltration fractionation did not significantly increase the DPP‐IV inhibitory activity of the AlcH fractions. Subjection of AlcH to simulated gastrointestinal digestion (SGID), which yielded SAlcH, resulted in a significant increase in DPP‐IV inhibitory activity ( P < 0.05), particularly after the intestinal phase of digestion. Following semi‐preparative reverse phase high performance liquid chromatography (RP‐HPLC) fractionation of SAlcH, fraction 28 was identified as having highest mean DPP‐IV inhibitory activity. Two novel DPP‐IV inhibitory peptides, ILDL and ILLPGAQDGL, with IC50 values of 1121.1 and 145.5 μm, respectively, were identified within fraction 28 of SAlcH following ultra‐performance liquid chromatography (UPLC)‐tandem mass spectrometry (MS/MS). BSG protein‐derived peptides were confirmed as having dual ACE and DPP‐IV inhibitory activities. Abstract : BSG‐PI hydrolysed with alcalase (AlcH) had a DPP‐IV IC50 of 3.57 ± 0.26 mg mL −1 . DPP‐IV inhibitory activity of the BSG‐PI was increased by SGID. Five peptides detected in the AlcH subjected to SGID (SAlcH) had a DPP‐IV IC50 < 200 µm . A novel DPP‐IV inhibitory peptide, LLPGAQDGL (IC50 of 145.5 µm ), was identified. Peptides with dual DPP‐IV and ACE inhibitory activities were present in SAlcH.