Synthesis and thrombin, factor Xa and U46619 inhibitory effects of non-amidino and amidino N²-thiophenecarbonyl- and N²-tosylanthranilamides

Thrombin (factor IIa) and factor Xa (FXa) are key enzymes at the junction of the intrinsic and extrinsic coagulation pathways and are the most attractive pharmacological targets for the development of novel anticoagulants. Twenty non-amidino N²-thiophencarbonyl- and N²-tosyl anthranilamides 1-20 and six amidino N²-thiophencarbonyl- and N²-tosylanthranilamides 21-26 were synthesized to evaluate their activated partial thromboplastin time (aPTT) and prothrombin time (PT) using human plasma at a concentration of 30 µg/mL in vitro. As a result, compounds 5, 9, and 21-23 were selected to study the further antithrombotic activity. The anticoagulant properties of 5, 9, and 21-23 significantly exhibited a concentration-dependent prolongation of in vitro PT and aPTT, in vivo bleeding time, and ex vivo clotting time. These compounds concentration-dependently inhibited the activities of thrombin and FXa and inhibited the generation of thrombin and FXa in human endothelial cells. In addition, data showed that 5, 9, and 21-23 significantly inhibited thrombin catalyzed fibrin polymerization and mouse platelet aggregation and inhibited platelet aggregation induced by U46619 in vitro and ex vivo. Among the derivatives evaluated, N-(30-amidinophenyl)-2-((thiophen-200-yl)carbonylamino)benzamide (21) was the most active compound.