Design,Synthesis And Biological Evaluation Of Pyridine Ring-modified Dabigatran Derivatives

Thrombotic diseases are a serious threat to human life and health worldwide.Thrombin,the key effector protease of the coagulation cascade,induces fibrin deposition and activates human platelets,which is critical to the progression of thrombotic diseases.Therefore,it is still hot to discovery and develop new effective and safe anticoagulant treatment for thromboembolic diseases.According to the important applications of bioisosteric replacements in the structural optimization of lead compounds,we designed a series of dabigatrn derivatives,employing software SYBYL-X 2.0 of computer-aided simulation and the thrombin protein(PDB:1KTS)as a ligand.Via michael addition,acylation,reduction,closed loop condensation,Pinner reaction and hydrolysis reaction,15 dabigatran derivatives which showed high scores using the thrombin protein as ligands were synthesized from 4-chloro-3-nitrobenzoic acid,ethyl acrylate and substituted aniline/substituted 2-aminopyridine,via Michael addition reaction;carboxylic acylating reaction,nitro reduction reaction,cyclization reaction,Pinner reaction and hydrolysis reaction.The structures of the target compounds were confirmed by 1H NMR,13C NMR and HR-MS analyzes.All these compounds exhibited more than 80%inhibition effects at 1 μg/mL concentration,which were preliminarily screened for inhibitory activity.And the IC50 values of the thirteen compounds were tested,with dabigatran(1.20 nM)and argatroban(9.88 nM)as positive control.Except to compounds 7j-1,all other compounds were found to have potent anthrombin activity in the range of dabigatran,which were better than argatroban.Moreover,arteriovenous thrombosis model was used to evaluate the antithrombotic activities in vivo of intravenous administration of compounds 7a and 7o.Interestingly,they all showed potent effects on arteriovenous thrombosis with inhibition rate of(85.58±2.89)%and(84.19±1.14)%,respectively,which were comparable to that of dabigatran(85.07±0.61)%.Secondly,compounds 7a and 7o were successfully docked in the binding cavity of thrombin.Compared to dabigatran,compound 7a and 7o not only was stabilized by one π-π bond with Trp60 and four hydrogen bonds,respectively with Asp189,Gly219,Argl73and Gly216,but also with Ile 174,Glu97A,Asn98 and Leu99 and other amino acid residues by van der Waals forces,which may be favorable to improve biological activity.The bioactivity results indicated that these two compounds could be further investigated to determine their anticoagulant activities.