The in vitro anti-diabetic and antioxidant properties of protein hydrolysate from rice wine lees and its main novel bioactive peptides: Revealing the interaction with proteins of insulin signaling pathways in silico

This study aimed to investigate the in vitro anti-diabetic and antioxidant activities of rice wine lees protein hydrolysate, and to screen and identify the main bioactive peptides with aforementioned bioactivities, as well as the potential mechanisms. Results revealed the protein hydrolysate obtained by simulated gastrointestinal digestion had good alpha-glucosidase inhibitory activity (IC50 = 2.06 f 0.04 mg/mL), antioxidant activity (2,2 ' azobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS): IC50 = 0.33 f 0.06 mg/mL; 2,2-diphenyl-1-pyridyl radical (DPPH): IC50 = 1.27 f 0.28 mg/mL) and the improvement of insulin resistance. A total of 36 peptides were identified from simulated intestinal digestive components, with molecular weights of 500-750 Da and lengths mainly centered on 5 amino acids. New peptides LLGDV and LGDEPL were further screened from the protein hydrolysate and showed good alpha-glucosidase inhibitory activities (LLGDV: IC50 = 6.43 f 0.18 mM, LGDEPL: IC50 = 6.50 f 0.16 mM) and the ameliorating effect on insulin resistance with an approximately 1.35fold increase in glucose consumption. Molecular docking and molecular dynamics displayed that the peptides were stably bound to alpha-glucosidase and proteins related to insulin signaling pathways through hydrogen bonding, Pi bonding and van der Waals force, which further expounded the potential mechanisms of hypoglycemic effect. These findings may lay a scientific and theoretical foundation for the development and utilization of the rice wine lees protein.