Study On The Anti-diabetes Agents Targeted With ?-glucosidase

Diabetes Mellitus is a health-threatening chronic metabolic disease,arose from insufficient insulin secretion and characterized by hyperglycemia.In recent years,the morbidity rate of diabetes has been constantly increasing.?-Glucosidase is a key enzyme in the regulation of the level of blood glucose.Thus,the search for efficient and safe ?-glucosidase inhibitors play an important role in the therapy of postprandial hyperglycemia.In this study,we explore the inhibitory effects and mechanisms of tannins,quinazolinone derivatives and quercitrin on ?-glucosidase,the main contents and results are summarized as follows:1.The inhibitory effect and mechanism of proanthocyanidins from Pyracantha fortuneana fruit on ?-glucosidaseTannins were extracted from Pyracantha fortuneana fruit(PFF),and their structures were investigated through 13 C nuclear magnetic resonance(13C NMR),high performance liquid chromatography(HPLC)and high-resolution mass spectrometry(HRMS).The results showed that these compounds were predominantly constituted of procyanidin with A-type and B-type linkage and coexistence of procyanidins glucoside and ellagic acid rhamnoside.Spectroscopy methods were used to analyze the inhibitory activity of PFF tannins on ?-glucosidase.The results demonstrated that these compounds exhibited excellent inhibitory effect on ?-glucosidase with the IC50 value of 0.15 ?g/m L,and they reversibly inhibited ?-glucosidase in a non-competitive type.The fluorescence quenching analysis revealed that PFF tannins statically quenched the fluorescence spectra by forming an inhibitor-?-glucosidase complex.Molecular docking results further indicated that the driving powers of the interaction between tannins and ?-glucosidase were hydrogen bonds and hydrophobic force.The main inhibitory mechanism of PFF tannins on ?-glucosidase may be due to the insertion of tannins into the pocket of the enzyme altering the catalytic configuration of the active site in a manner,thus reducing substrate binding affinity.The findings of this work provided a new perspective that tannins from PFF with a possibility to be used as novel natural anti-diabetic agents.2.Quinazolinone derivatives: synthesis and comparison of inhibitory mechanisms on?-glucosidaseIn this study,eight quinazolinone derivatives were designed and synthesized.Their inhibitory activities on ?-glucosidase were assessed in vitro.Two compounds:2-(4-chlorophenyl)-quinazolin-4(3H)-one(CQ)and2-(4-bromophenyl)-quinazolin-4(3H)-one(BQ)were found to be potent inhibitors of?-glucosidase with IC50 values of 12.5 ?M and 15.6 ?M,respectively.Spectroscopy methods were performed to analyze the inhibitory mechanisms of both compounds on?-glucosidase.The results revealed that they reversibly inhibited ?-glucosidase in a non-competitive manner.CQ and BQ could statically quench the fluorescence spectra by formation of an inhibitor-?-glucosidase complex.The interaction between CQ and?-glucosidase depended on hydrogen bonds,electrostatic and hydrophobic force,while the driving force of the binding between BQ and the enzyme was hydrophobic.The docking results showed that BQ was less active than CQ against ?-glucosidase because of its weaker interaction with the enzyme.In brief,the quinazolinone derivatives identified in this work were potentially promising candidates for developing as novel anti-diabetic agents.3.The inhibitory effect and mechanism of quercitrin on ?-glucosidaseIn current work,enzyme kinetics,fluorescence quenching and molecular docking were carried out to explore the inhibitory effect and mechanism of quercitrin on?-glucosidase.The results showed that quercitrin exhibited excellent ?-glucosidase inhibitory activity with the IC50 value of 0.275 mM.Enzyme kinetics results showed that quercitrin reversibly inhibited ?-glucosidase in a mix type.The fluorescence quenching analysis showed that quercitrin caused a static quench by formation of an inhibitor-?-glucosidase complex.Molecular docking results indicated that the driving powers of the interaction between quercitrin and ?-glucosidase were hydrogen bonds and hydrophobic force.These results we can speculated that the main inhibitory mechanism of quercitrin on ?-glucosidase may be due to the insertion of quercitrin into the pocket of the enzyme altering the conformation of the enzyme,thus reducing substrate binding affinity.The present study provides theoretical foundation of developing and exploring novel anti-diabetic agents.