Germination of Phaseolus vulgaris and alcalase hydrolysis of its proteins produced bioactive peptides capable of improving markers related to type-2 diabetes in vitro

• Germination and alcalase hydrolysis of common bean generated bioactive peptides.
• High antioxidant capacity was achieved after germination and alcalase hydrolysis.
• The RGPLVNPDPKPFL peptide is predicted to inhibit DPP-IV by interaction with its active site.
• Peptides from gastrointestinal digestion were able to stimulate insulin secretion in vitro.

The aim of this study was to evaluate the effect of germination and alcalase hydrolysis of common bean proteins on the generation of bioactive peptides with potential to reduce parameters related to the risk of developing type-2 diabetes (T2D) in vitro. Germination (25 °C up to 72 h) and alcalase hydrolysis (up to 4 h) produced peptides with high antioxidant capacity (1085 μmol TE/g soluble protein, SP). After 24 h of germination, there was an increase of 44% in α-amylase inhibitory capacity of the peptides relative to acarbose (1 mM). Simulated gastrointestinal digestion of the non-germinated and non-hydrolyzed sample (G0-0h) produced bioactive peptides that inhibited dipeptidyl peptidase-IV (DPP-IV) (IC50 = 1.2 mg SP/mL); however, the IC50 was not improved by either germination or alcalase hydrolysis. Insulin secretion by glucose stimulated (20 mM) INS-1E pancreatic β-cells, increased 45% from the basal state with 2 mg SP/mL of G0-0h. Germination did not improve the stimulation of insulin. Computational modeling showed that the peptide RGPLVNPDPKPFL obtained after 48 h germination and 1 h alcalase-hydrolysis was able to inhibit DPP-IV by interacting with its S1, S2, and S3 pockets of the active site. Germination and alcalase hydrolysis can be applied to improve some markers related to the management of T2D. Furthermore, simulated gastrointestinal digestion of common bean proteins without any treatment produced bioactive peptides with the ability to inhibit DPP-IV, resulting in increased insulin released from pancreatic cells in vitro.