Screening of α-Glucosidase Inhibitory Peptides from Tea Leaves using Ultrafiltration Affinity Combined with Liquid Chromatography-Mass Spectrometry and Molecular Docking Technology

Objective: To screen for tea peptides with inhibitory activity against α-glucosidase. Methods: The response surface method was used to optimize the preparation process of tea peptides. Affinity ultrafiltration was used to isolate tea peptides that bind with α-glucosidase, and liquid chromatography-mass spectrometry was used to determine the sequence of the isolated peptides. Virtual screening was performed using bioinformatics methods. Results: The optimal preparation process of tea leaf enzymatic hydrolysis products was alkaline protease hydrolysis temperature of 50 ℃, enzymatic hydrolysis time of 3 h, and a liquid-to-solid ratio of 10:1 (mL/g). The α-glucosidase inhibitory rate was 57.29%. From this, 624 peptide segments were identified, and LIGF was selected for its α-glucosidase inhibitory activity. At a concentration of 5 mg/mL, LIGF exhibited a maximum inhibition rate of 88.13% against α-glucosidase and an IC₅₀ value of 1.22 mg/mL. Molecular docking showed that LIGF could form 5 hydrogen bonds with α-glucosidase, and the binding energy was −3.51 kJ, indicating a high affinity, stability and ability to bind to α-glucosidase. Conclusion: LIGF had potential value as a therapeutic drug for type II diabetes.