Molecular Modeling Study,Synthesis And Biological Evaluation Of Combretastatin A-4 Analogues As Tubulin Inhibitors

Combretastatin A-4（CA-4）is the most potent naturally occurring combretastatin known in regards to both tubulin binding ability and cytotoxicity.It inhibits tubulin polymerization by acting on the colchicine binding site as tubulin polymerization inhibitor.In this present,64tubulin polymerization inhibitors of five-membered heterocycle-based combretastatin A-4analogues were studied by combination of molecular modeling techniques including3D-QSAR（three-dimensional quantitative structure activity relationship）,molecular docking and molecular dynamics（MD）simulation.The reliable 3D-QSAR models were established,and the corresponding statistical parameters of the CoMFA and CoMSIA models were q²=0.702,r²=0.988,r²pred=0.711 and q²=0.700,r²=0.986,r²pred=0.623.According to the contour maps analysis of the CoMFA and CoMSIA models,some potent compounds were designed based on the known pharmacophore moieties.Molecular docking identified a number of key amino acid residues that interact with the colchicine binding site of tubulin.To further validate the reliability of molecular docking results,20 ns MD simulations were successfully performed to confirm the detailed binding mode.The binding free energy was calculated based on the equilibrium production of MD.According to the results of binding free energy,four compounds were synthesized and the compound 13a exhibits potent antiproliferative activity(IC₅₀ value of 1.314μM against HepG2 cells,IC₅₀ value of 1.371μM against A549 cells)and inhibition of tubulin polymerization activity(IC₅₀ value of 0.86μM).Compound 13b also exhibits a good activity against HepG2 cells(IC₅₀ value of 4.754μM).The biological evaluation demonstrated that the models were effective for the development of novel potent tubulin inhibitors.At the same time,the ADMET properties of the collected CA-4 analogues and novel design inhibitors were also predicted,which provide some reference data for the early stages of drug development.