Preparation and Mechanistic Characterization of α-Glucosidase Inhibitory Peptides from Elaeagnus mollis Oilseed Meal

Elaeagnus mollis oilseed (EMO) meal is a protein-rich by-product that may serve as a novel source of food-derived α-glucosidase inhibitory peptides. This study aimed to obtain EMO peptide fractions with enhanced α-glucosidase inhibition and to clarify the activity, stability and mechanism of the most active fraction. Fourteen proteases were compared, and 3.350 acidic protease was selected to establish an optimized hydrolysis process. The resulting EMO hydrolysate showed an IC₅₀ of 9.11 mg/mL against α-glucosidase and no detectable cytotoxicity towards HEK-293T cells at 0.1-12.0 mg/mL. Ultrafiltration yielded four fractions, among which the 3-10 kDa fraction exhibited the highest inhibition and maintained substantial activity under acidic pH (2-6), -20-50 °C, NaCl ≤ 5% and simulated gastrointestinal digestion. Kinetic analysis indicated mixed-type inhibition, while fluorescence, circular dichroism and molecular docking suggested that peptides in this fraction bind near the catalytic site of α-glucosidase and induce local conformational changes. These findings support EMO-derived 3-10 kDa peptides as stable, non-cytotoxic α-glucosidase inhibitors with potential as functional ingredients for dietary management of type 2 diabetes.