Oat globulin peptides regulate antidiabetic drug targets and glucose transporters in Caco-2 cells

Abstract

This study clarified the effects of well-characterized oat globulin peptides on antidiabetic drug targets (dipeptidyl peptidase IV [DPP4], α-glucosidase, glucose transporters 2 and 5 [GLUT2, GLUT5]) in Caco-2 cells. Twenty-two peptides with over 8 residues were identified from the tryptic hydrolysates (OGb, MM < 3 kDa) of oat globulin using liquid chromatography-mass spectroscopy. Computational docking demonstrated that LQAFEPLR (−8.8 kcal/mol) and EFLLAGNNK (−9.1 kcal/mol) effectively inactivated DPP4 binding to its active sites with low interaction energy. OGb, LQAFEPLR and EFLLAGNNK potently inhibited DPP4 and α-glucosidase activity in vitro concentration-dependently. Additionally, OGb (IC50, 188.1 μg/mL) and LQAFEPLR (141.7 μM) concentration-dependently inhibited DPP4 activity in Caco-2 cells. Specifically, they significantly downregulated the expression of DPP4 protein in Caco-2 cells (p < .05). However, these oat peptides also upregulated the expressions of α-glucosidase, GLUT2 and GLUT5 proteins in the cells. Overall, oat globulin peptides have contrasting modulatory effects on these antidiabetic drug targets.