Rice bran peptide with α-glucosidase inhibition activity: Preparation, evaluation and molecular mechanism

Abstract

The role of bioactive peptides in diabetes management has attracted extensive attention. In this study, the 1–3 kDa fraction of rice bran peptides (RBPs) was obtained by the hydrolysis of alkaline and dispase, and the following ultrafiltration demonstrated excellent α-glucosidase inhibition activity with an IC50 value of 1.17 ± 0.08 mg/mL and exhibited postprandial hypoglycemic activity in vivo. Enzymatic kinetics studies revealed that RBPs (1–3 kDa) inhibited α-glucosidase via competitive inhibition. Thirty-two peptides were characterized from RBPs (1–3 kDa) by LC-MS/MS. Virtual screening was applied to screening the new potential α-glucosidase inhibitor, and NVEKKDPTGA (NA-10) with a binding energy of −10.24 kcal/mol to α-glucosidase was selected as the most promising peptide. Molecular docking reflected that Ala at the C-terminal and KK amino acid cluster play a key role in forming hydrogen bonds with the catalytic site of α-glucosidase, which might be critical for the α-glucosidase inhibitory effect. This study proved that RBPs could be a promising bio-factor food ingredient for diabetes prevention.