Conception, synthèse et évaluation biologique de coumarines en tant qu'inhibiteurs de protéases à sérine impliqué dans la cascade de coogulation

Serine proteases play important roles in numerous physiological processes and are also involved in pathological states. Therefore, the development of specific inhibitors of proteases is promising strategies in the treatment of these diseases.
Our previous works focused on á-chymotrypsin (á-CT), an interesting biological tool for the evaluation of new synthetic inhibitors of serine proteases, and on human leukocyte elastase (HLE) which is implicated in acute respiratory distress syndrome, pulmonary emphysema and cystic fibrosis. The synthesized compounds, characterized by a coumarin ring bearing in position 3 an alkyl, aryl ester, thioester, amide or ketone function and in position 6 an electrophilic moiety were found to act as mechanism-based inhibitors. The ki/KI ratios for the most active compounds were in the range of 10⁵-10⁶ M^-1 s^-1 for á-CT and of 10⁴-10⁵ for HLE.
Recently, we focused on serine protease implicated in the coagulation cascade and especially on thrombin, factor Xa and factor VIIa. These enzymes, largely involved in thrombotic disorders, are attractive targets for the development of new anticoagulant drugs.
New pharmacomodulations of coumarin derivatives have been planed to target these proteases. To evaluate drug inhibitory potency, we developed several in vitro methods on isolated enzymes including screening tests and inactivation parameters determination (ki and KI). We also studied by mass spectrometry and enzymatic reactivation studies the reactive pathway followed by the inhibitors.
In the future, we will undertake a pharmacological evaluation of our compounds including thrombin, factor Xa and factor VIIa inhibitors. In this evaluation, we will first study the in vivo antithrombotic profils in various rat models of thrombosis. We will next examine effects on coagulation parameters (APTT, PT, level of TAT) and on platelet function (platelet aggregation, PFA-100).