The Virtual Screening Of FtsZ Fiber Depolymerization Inhibitors;Design,Synthesis And Antibacterial Evaluation Of Icariin Derivatives

Objective:Since bacterial infections are common in life and the use of antibacterial drugs in society is extensive,the species of drug resistant bacteria have increased dramatically.There is an urgent need for us to develop new drugs to remove the gangers of infectious diseases.The first thing that needs to be done to develop a new antibacterial drug is to look for potential lead compounds with a completely new structure.From the two strategies of virtual screening and natural product derivatization,this paper studied the virtual screening of FtsZ fiber depolymerization inhibitors and the design and synthesis of icariin derivatives,and performed the icariin derivatives.Then the antibacterial activity of Icariin derivatives was tested to obtain new drug candidates with high efficiency and low toxicityMethod:(1)First of all,using the SBP module located in the virtual screening software Discovery Studio 2017R2,we generated a pharmacophore model based on the three-dimensional structure of the ligand-receptor complexes of the FtsZ protein.Then,a multistep virtual screening protocol was built and 572773 compounds from ChemDiv were screened.In the first step,screening was performed using the Verber principle and the constructed pharmacophore;in the second step,the four docking methods including Libdock,LigandFit,CDDOCKER,and Flexble Docking were used for combinatorial screening.Finally,in order to further analyze the interaction characteristics of the ligand and the receptor,The compounds which obtained from the above screening were classified and then four compouds was selected for the next step to analyze the interaction mode by the molecular dynamics method.(2)With methanol as solvent,under the condition of heating reflux,add 20%sulfuric acid as catalyst,we got a intermediate containing hydroxyl,followed by introducing a series of compounds at the intermediate to form a series of Icarin derivatives.Then we tested the antibacterial activity of the Icarin derivatives,oxacillin and norfloxacin were the control material.Result:(1)We have created a pharmacophore model consisting of seven interaction features.The comprehensive evaluation index of this pharmacophore is 2.10,which fully meet requirements for coarse screening.(2)Based on the establishment of pharmacophores,we designed a multi-level screening strategy.First of all,the Verber principle was used to screening,and 52,8021 small molecules were obtained.Then we used the constructed pharmacophore to screen the database,15000 compounds were received in this step.In the second step,we used the docking software Libdock and LigandFit for rapid screening.5000 compounds were received in this step,ThenCDOCKER and Flexible Docking were used for screening,86 compounds were obtained by this step.(3)We divided 86 potential active compounds into four groups and selected one compound in each group.Each system was subjected to a 5ns molecular dynamics simulation,and the root mean square deviation(RMSD)of each system tended to be stable.The results of the kinetic simulations suggest that the hydrogen bond interaction plays a very important role in the stability of the respective systems.(3)21 Icarin derivatives were designed and synthesized,and all the structures were characterized by the methods of MS and 1HNMR.At the same time,we have optimized the synthetic route:when synthesizing the intermediates,using methanol as solvent for refluxing can simultaneously meet the three requirements of our design,and further obtain the intermediates.In the second step reaction,when the molar ratio of the sulfonyl chloride to the intermediate was 1.1:1,the yield was highest.(4)Then we tested the antibacterial activity of the Icariin derivatives,oxacillin and norfloxacin were the control material.The results showed that the antibacterial concentration of all compounds against E.coli was above 64μg/mL,and that against sensitive S.aureus was between 4 ug/mL and 32 μg/mL.However,the antibacterial activity of the compounds against Staphylococcus aureus was poor,except that the inhibitory concentration of compound 5 was 8 μg/mL,the others were between 16 μg/mL and 64 p.g/mL.Conclusion:(1)Through multiple screening strategies,we obtained 86 compounds that may have potential antibacterial activity.The results of molecular dynamics simulations indicate that hydrogen-bond interactions play a important role in their stabilization.(2)The reaction step for the synthesis of icariside derivatives is simple,the conditions are mild,and the yield meets the requirements.It is an ideal method for synthesizing Icarin derivatives.In the next antibacterial activity experiment,most of the target compounds had poor antibacterial activity against E.coli,but the antibacterial activity of S.aureus-sensitive strains was somewhat improved.Among them,compound 5 also had a certain effect on S.aureus,indicating that the restructuring has initially achieved our purpose.