Discovery of 2-aryloxy-4-amino-quinazoline derivatives as novel protease-activated receptor 2 (PAR2) antagonists

Protease-activated receptor 2 (PAR(2)) is a member of G protein-coupled receptor and its activation initiates diverse inflammatory responses. Recent studies suggest that antagonists of PAR(2) may provide a novel therapeutic strategy for inflammatory diseases. In this study, we have developed a series of 2-aryloxy-4-amino-quinazoline derivatives as PAR(2) antagonists and examined their effects against LPS-induced inflammatory responses in RAW 264.7 macrophages. Among these derivatives, compound 2f displayed the greatest antagonistic activity with the IC50 value of 2.8 mu M. Binding modes of the newly identified PAR(2) antagonists were analyzed by molecular docking using IFD/MM-GBSA methods in the putative binding site of PAR(2) homology model. Moreover, 2f demonstrated significant inhibitory effects on the LPS-activated pro-inflammatory mediators including nitric oxide (NO), prostaglandin E-2 (PGE(2)), interleukin- 1 beta (IL-1 beta), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) through the regulation of various intracellular signaling pathways involving nuclear factor-kappa B (NF-kappa B), activator protein 1 (AP-1) and the mitogen-activated protein kinases (MAPK). Furthermore, administration of 2f significantly reduced the mortality of LPS-induced sepsis in mice. These results provide useful insights into the development of novel PAR(2) antagonists with anti-inflammatory activity in vitro and in vivo. (c) 2015 Elsevier Ltd. All rights reserved.