Identification and interaction mechanism of novel α-glucosidase inhibitory peptides in mulberry leaf: In silico analysis and multispectroscopic investigation.

This study employed a comprehensive approach integrating peptidomics, in silico analysis, and multispectroscopic techniques to screen novel α-glucosidase inhibitory peptides from mulberry leaf protein digests. The following α-glucosidase inhibitory peptides were selected from 141 identified peptides: GGLDFTK (IC50 = 0.149 mg/mL), VLAKALR (IC50 = 0.432 mg/mL), SLLIDLSR (IC50 = 0.648 mg/mL), VFGFKALR (IC50 = 0.168 mg/mL), IVDIPSYR (IC50 = 0.274 mg/mL), and FSTVIHER (IC50 = 0.186 mg/mL). All six peptides exhibited potential antioxidant activity and high thermal stability. The α-glucosidase inhibitory activity of these peptides was enhanced under weak acidic conditions and in the presence of sodium chloride at an appropriate concentration. Multispectroscopic analysis revealed that these six peptides disrupt the stable conformation of α-glucosidase by altering its microenvironment, forming non-covalent bonds, and modifying the enzyme's secondary structure. Furthermore, molecular docking and molecular dynamics simulations revealed that these six peptides primarily bind to key active residues (Asp379, Arg429, or Arg400) on α-glucosidase via hydrogen bonds, hydrophobic interactions, van der Waals forces, and electrostatic interactions. The study demonstrates that mulberry leaves are a potential source of α-glucosidase inhibitory peptides, providing new insights into their functional utilization.