Synthesis and evaluation of novel and potent protease activated receptor 4 (PAR4) antagonists based on a quinazolin-4(3H)-one scaffold

In this study, we explored the activity of quinazolin-4(3H)-one-based PAR4 antagonists, beginning with their IDT analogues. By repeated structural optimisation, we developed a series of highly selective PAR4 antagonists with nanomolar potency on human platelets. Of these, 13 and 30g, with an 8-benzo[d]thiazol-2-yl-substituted quinazolin-4(3H)-one structure, showed optimal activity (h. PAR4-AP PRP IC50 = 19.6 nM and 6.59 nM, respectively) on human platelets. Furthermore, 13 and 30g showed excellent selectivity for PAR4 versus PAR1 and other receptors (IC50s > 10 μM) on human platelets. And 13 and 30g were lack of cross-reactivity for PAR1 or PAR2 (PAR1 AP FLIPR IC50 > 3162 nM, PAR2 AP FLIPR IC50 > 1000 nM) in the calcium mobilization assays. Metabolic stability assays and cytotoxicity tests of 13 and 30g indicated that these compounds could sever as promising drug candidates for the development of novel PAR4 antagonists. In summary, the quinazolin-4(3H)-one-based analogues are the first reported chemotypes with excellent activity and selectivity against PAR4, and, in the current study, we expanded the structural diversity of PAR4 antagonists. The two compounds, 13 and 30g, found in our study could be promising starting points with great potential for further research in antiplatelet therapy.PMID:34391031 | DOI:10.1016/j.ejmech.2021.113764
Source: European Journal of Medicinal Chemistry - Category: Chemistry Authors: Source Type: research