Exploring dipeptidyl peptidase-IV inhibitory peptides from Tartary Buckwheat protein: A study of hydrolysis, fractionation, and molecular interactions.

Tartary buckwheat, a protein-rich pseudocereal with anti-diabetic effects, has not yet been fully explored as a source of dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides. This study aims to discover novel DPP-IV inhibitory peptides from tartary buckwheat protein (TBP). Five hydrolysis methods were employed, with simulated gastrointestinal digestion (SGID) releasing the most active DPP-IV inhibitory hydrolysates, showing both the highest degree of hydrolysis (22.66 ± 1.12%) and inhibition activity (41.81 ± 1.52% at 1.25 mg/mL). In addition, ultrafiltration enriched the <3 kDa fraction with the highest inhibitory rate, and further purification using reverse-phase high-performance liquid chromatography concentrated the DPP-IV inhibitory peptides in the first fraction (F1). Nano liquid chromatography-tandem mass spectrometry analysis identified 10 new peptides in F1, among which the peptide Leu-His-Ile-Val-Gly-Pro-Asp-Lys (LHIVGPDK) exhibited the strongest inhibitory effect, with an IC value of 1.61 mM. Kinetic studies revealed that LHIVGPDK acts as a mixed-type inhibitor, and molecular docking indicated that it inhibits DPP-IV by forming stable complexes through five types of interactions, with hydrogen bonds playing a key role. This study underscores TBP's DPP-IV inhibitory potential and anti-diabetic properties, reinforcing the value of tartary buckwheat as a beneficial food for diabetes management. PRACTICAL APPLICATION: This research identified new peptides from Tartary buckwheat protein that effectively inhibit DPP-IV, an enzyme associated with diabetes management. These findings suggest potential applications in developing functional foods to help control hypoglycemia.