Full Length ArticleDiscovery and assessment of water soluble coumarins as inhibitors of the coagulation contact pathway

- Coumarins targeting the contact pathway were synthesized and assessed.
- For the first time, such coumarins impact plasma and blood assays.
- Compound 1 emerges as a small-molecular-weight inhibitor of the contact pathway.
- The 8-channel microfluidic model is a powerful screening tool for weak inhibitors.
- A phenyl-guanidine moiety is better than an ethyl-guanidine to inhibit FXIIa.

Over the last decade, the coagulation factor XIIa (FXIIa) has seen renewed interest as a therapeutic target. Indeed, its inhibition could offer a protection against thrombosis without increasing the risk of bleeding. Moreover, it could answer the need for a safe prevention of blood-contacting medical devices-related thrombosis. Among the FXII and FXIIa inhibitors already described in literature, organic small-molecular-weight inhibitors are rather left behind. In this study, we were focused on the discovery and assessment of water soluble small molecules. First, a search within our library of compounds flagged two promising hits. Indeed, enzymes and plasma assays suggested they have a greater activity on the contact factors (FXIa, plasma kallikrein and FXIIa) than on the TF pathway. Then, simple pharmacomodulations were undertaken with the aim to design more selective FXIIa inhibitors. This afforded compounds having different degrees of selectivity. All compounds were finally screened in whole blood using an 8-channel microfluidic model and thromboelastometry measurements. Interestingly, all molecules interfered with the thrombus formation and one of them could be considered as a small organic contact inhibitor.