The molecular mechanism of the interaction between resveratrol and trypsin was studied using fluorescence spectroscopy (intrinsic fluorescence, synchronous fluorescence, three-dimensional fluorescence), ultraviolet-visible (UV-vis) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and the molecular docking method, as well as through enzyme activity and antioxidant assay. The fluorescence experiments (the Stern–Volmer quenching constants (K_SV)) indicated that resveratrol quenched the intrinsic fluorescence of trypsin through the static quenching mechanism. The number of binding sites was about one. The thermodynamic functions ΔG < 0 and ΔH > 0, ΔS > 0 of the binding process, indicating that the combination of the resveratrol and trypsin processes was a spontaneous exothermic reaction and that the hydrophobic effect was the main force between them. UV-vis spectra, synchronous fluorescence spectra and three-dimensional fluorescence spectra analysis showed that the combination of resveratrol and trypsin induced changes in the microenvironment around the fluorophores of trypsin, resulting in alterations in the spatial structure of trypsin. FT-IR spectroscopy indicated that the contents of the α-helixes and β-turns in trypsin decreased and that the contents of the β-sheets, random coils and antiparallel β-sheets increased. All these experimental results were verified and reasonably explained by the molecular docking results. Upon resveratrol and trypsin binding, the enzyme catalytic activity of trypsin and the antioxidant of resveratrol decreased. Results from this study would be useful in elucidating the molecular mechanisms of the interactions between resveratrol and trypsin and contribute to making full use of resveratrol in the food industry.

A new antidiabetic peptide was screened from the collagen hydrolysates of Andrias davidianus skin by the network pharmacology method, and its glucose-lowering activity was detected by α-glycosidase inhibition assay and cell assay.

In this study, a novel hypoglycemic peptide Gly-Pro-Ala-Gly-Ala-Pro (GPAGAP) was screened from skin collagen hydrolysates of Andrias davidianus by network pharmacology and bioinformatics, and its hypoglycemic mechanism was predicted. Meanwhile, the improvement of insulin resistance (IR) in HepG2 cells were detected. Through network pharmacology screening, GPAGAP had good drug-like properties, and 105 targets of GPAGAP overlap with diabetes mellitus type 2 (T2DM) targets. These targets were mainly enriched in the PI3K-Akt signaling pathway, TNF signaling pathway, IR and other signaling pathways related to T2DM. The results of IR-HepG2 cell model experiments showed that GPAGAP could reduce IR of HepG2 cells induced by high-glucose and high-insulin, and improve glucose consumption of IR-HepG2 cells. GPAGAP could increase the glycogen content, hexokinase (HK) and pyruvate kinase (PK) activities of IR-HepG2 cells, inhibit the accumulation of triglyceride (TG) and total cholesterol (TC) in IR-HepG2 cells, and enhance the activity of superoxide dismutase (SOD) in IR-HepG2 cells, reduce the content of malondialdehyde (MDA) and reactive oxygen species (ROS) in IR-HepG2 cells. The above results suggested that GPAGAP could through multi-target and multi-pathway to improve the glucose metabolism, lipid metabolism and oxidative stress response of IR-HepG2 cells. It has the potential effect of improving insulin resistance in T2DM.

There is a growing demand for natural and potent α-glucosidase inhibitors due to the rising prevalence of diabetes. In this study, newly identified α-glucosidase inhibitory peptides were identified from the tryptic hydrolysate of hemp seed proteins based on peptidomics and in silico analysis. A total of 424 peptides, primarily derived from four cupin-type-1 domain-containing proteins, were identified, and 13 ultimately were selected for validation based on their higher PeptideRanker scores, solubility, non-toxicity, and favorable ADMET properties. Molecular docking revealed that these 13 peptides primarily interacted with α-glucosidase via hydrogen bonding and hydrophobic interactions. Among them, three novel peptides—NPVSLPGR (−8.7 kcal/mol), LSAERGFLY (−8.5 kcal/mol), and PDDVLANAF (−8.4 kcal/mol)—demonstrated potent α-glucosidase inhibitory activity due to their lower binding energies than acarbose (−8.1 kcal/mol), the first approved α-glucosidase inhibitor for type 2 diabetes treatment. The molecular mechanism analysis revealed that the peptides NPVSLPGR and LSAERGFLY inhibited α-glucosidase by simultaneously blocking substrate entry through occupying the entrance of the active site gorge and preventing catalysis by binding to active sites. In contrast, the peptide PDDVLANAF primarily exerted inhibitory effects by occupying the entrance of the active site gorge. Molecular dynamics simulation validated the stability of the complexes and provided additional insights into the molecular mechanism determined through docking. These findings contribute essential knowledge for the advancement of natural α-glucosidase inhibitors and offer a promising approach to effectively manage diabetes.