Study On Mechanism Of Five Flavonoids Inhibiting HIAPP Aggregation And NtMGAM Activity Based On Molecular Simulation

Type 2 diabetes mellitus（T2DM）is currently one of the main challenges of modern medicine and public health.Inhibiting human islet amyloid polypeptide,hIAPP,or Amylin)hIAPP aggregation and reducing the toxicity of its oligomers and Nt-Maltase-Glucoamylase（NtMGAM）enzyme activity are potential strategies for the treatment and control of T2DM disease development:hIAPP oligomers can lead to inhibition of metabolic functions,induce oxidative stress and apoptosis,and damage cell membranes Causes isletβ-cells to apoptosis,resulting in reduced insulin production;NtMGAM enzyme,which hasα-glucosidase activity,has a shallow binding pocket at its active site and is difficult to inhibit by Acarbose.According to literature reports in recent years,five natural flavonoids,including Genistein,Rutin,Quercetin,Epigallocatechin gallate（EGCG）and Sililibin,present effective inhibition on hIAPP aggregation through traditional experimental methods.However,the detailed mechanisms of their inhibition remain unclear.Based on this,this paper explores the mechanism of five flavonoids inhibiting hIAPP aggregation through computer simulation methods including molecular docking and molecular dynamics simulations;and explores whether these five types of flavonoids can competitively inhibit NtMGAM enzyme which is another target of T2DM.This paper is to explore whether these five flavonoids can be dual-targeted to treat and control the disease development of T2DM patients,and the main findings are as follows:The computer simulation results of five flavonoids with hIAPP show that:（I）These five flavonoids can be depolymerized by binding to two regions of hIAPP(Leu₁₂-Ala₁₃-Asn₁₄ and Asn₃₁-Val₃₂-Gly₃₃-Ser₃₄-Asn₃₅)to depolymerize chains A and B which are in direct contact with hIAPP;（II）The inhibitory ability is:Genistein>Rutin>Quercetin>EGCG>Silibinin;（III）These five flavonoids exhibit a similar mechanism of hIAPP pentamer disaggregation:they loosen the two peptide chains that are in direct contact with them,potentially destroying the hIAPP oligomer.（IV）The mutation of key amino acid residues results shows that the 28th（Ser）,12th（Leu）and 32th（Val）amino acid residues of hIAPP have an important effect on the structural stability of hIAPP pentamers.These three amino acid key residues may be potential targets for designing anti-hIAPP aggregation inhibitors.The computer simulation results of five flavonoids with NtMGAM show that:（I）The NtMGAM active pockets tend to combine with sugar rings and aromatic rings;EGCG and Rutin have the potential to inhibit NtMGAM activity,and their ability to bind to active pocket of NtMGAM is better than Acarbose;（II）The binding ability of pentasaccharide and active pocket of NtMGAM enzyme is better than that of hexasaccharide and it indicates that the structure of enzyme active pocket should not be too large;（III）The disturbance of solvent molecules is a key factor affecting the binding stability of inhibitor molecules and active pocket of NtMGAM.Therefore,in the design of NtMGAM inhibitors,the structure of the inhibitor needs a structure that shields the solvent outside the active pocket,in order to reduce the disturbance of the inhibitor by the solvent.The above results indicate that EGCG and Rutin may have the dual targeting effect of inhibiting hIAPP aggregation and NtMGAM.Three key targets have been found in exploring the mechanism of inhibiting hIAPP aggregation.In exploring inhibitors of NtMGAM enzyme activity,the structure of the inhibitor to block external solvent interference has become very important.Through this work,it may help to explore the mechanism of flavonoids inhibiting hIAPP aggregation and inhibiting NtMGAM activity at the atomic level,and will help to screen,modify and design new inhibitors.