Investigation on antioxidant, angiotensin converting enzyme and dipeptidyl peptidase IV inhibitory activity of Bambara bean protein hydrolysates

Protein isolate was hydrolysed by Alcalase, thermolysin and trypsin. BBPH produced by Alcalase showed highest angiotensin-converting enzyme (ACE) inhibitory properties (IC50: 52 µg/mL). Hydrolysates produced by Alcalase and thermolysin exhibited similar dipeptidyl peptidase-IV (DPP-IV) inhibitory activity (IC50: 1.73 mg/mL), while low inhibitory activity was observed for hydrolysate produced by trypsin. BBPH also showed protective effect against oxidative stress with significant 2,2-diphenyl-1-picrylhydrazyl radical scavenging and ferrous chelating activity. Bioactive peptides of BBPH produced by thermolysin showed better resistance to simulated gastrointestinal digestion (SGID), while the DPP-IV and ACE inhibitory properties were significantly reduced. Molecular weight distribution showed significant reduction in peptides of the molecular weight range 200-400 Da in BBPH produced by Alcalase, after SGID. LC-ESI-TOF-MS and in silico analysis showed the presence of potential peptides with both ACE and DPP-IV inhibitory properties in BBPH produced by thermolysin.