Preparation, identification, and molecular mechanism of novel DPP-IV inhibitory peptides from pumpkin seed: In silico screening and experimental validation

The rising prevalence of Type 2 diabetes mellitus (T2DM) and the limitations of synthetic DPP-IV inhibitors emphasize the need for natural alternatives with fewer side effects. This study explored pumpkin seed protein (PSP) as a source of potential DPP-IV inhibitory peptides. Through in silico screening and experimental validation, seven novel peptides were identified, with LPGFF, LPGF, and MPLPA exhibiting potent inhibitory activities (IC₅₀: 449.68–478.88 μM). Molecular docking and dynamics simulations revealed stable binding to DPP-IV's active site, interacting with key residues (Tyr547, Ser630, Tyr662, Arg125, Glu205). Kinetic analysis indicated competitive inhibition. In vivo studies in C57BL/6 J mice demonstrated significant hypoglycemic effects, reducing blood glucose AUC by 14.98–18.65 % at 100 mg/kg. The peptides also exhibited stability under varying temperatures, pH, and gastrointestinal conditions. These findings position PSP as a promising source of DPP-IV inhibitors and highlight the potential of in silico screening for bioactive peptide discovery in T2DM management.