Quercetin was extracted from Portulaca oleracea L. through biphasic acid hydrolysis to investigate its potential as a suppressor of dipeptidyl peptidase IV (DPP-IV) and its hypoglycemic effect in type 2 diabetic mice. The extraction procedure was optimized utilizing the response surface method (RSM) in a single-factor experimental setting. An extraction efficiency of 0.675% was achieved using the following optimized parameters: 0.064 mol/L vitriol, 1 : 109.155 solid-liquid ratio, and 21.408 min ultrasonication. Overall, findings indicate the effectiveness of quercetin extraction. A mouse model for type 2 diabetes was established to receive oral treatment with various quercetin concentrations for 8 weeks. Fasting blood glucose (FBG) and the DPP-IV activity in the serum were significantly reduced. The weight and insulin levels of the mice in the quercetin group were raised compared to those in the model group ( < 0.01). Quercetin dose-dependently inhibited postprandial blood glucose excursions, as demonstrated by the oral glucose tolerance test. These results confirmed that quercetin has hypoglycemic effects and considerably improves insulin sensitivity via DPP-IV targeting.
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 50 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.
危险品化学品经营许可证（带存储）