Potent Agonists of the Protease Activated Receptor 2 (PAR2)

Novel peptidomimetic pharmacophores to PAR(2) were designed based on the known activating peptide SLIGRL-NH2. A set of 15 analogues was evaluated with a model cell line (16HBE14o-) that highly expresses PAR(2). Cells exposed to the PAR2 activating peptide with N-terminal 2-furoyl modification (2-furoyl-LIGRLO-NH2) initiated increases in intracellular calcium concentration. ([Ca2+](i) EC50 = 0.84 mu M) and in vitro physiological responses as measured by the xCELLigence real time cell analyzer (RTCA EC50 = 138 nM). We discovered two selective PAR(2) agonists with comparable potency: compound 1 (2-aminothiazol-4-yl; Ca2+ EC50 = 1.77 mu M, RTCA EC50 = 142 nM) and compound 2 (6-aminonicotinyl; Ca2+ EC50 = 2.60 mu M, RTCA EC50 = 311 nM). Unlike the previously described agonist, these novel agonists are devoid of the metabolically unstable 2-furoyl modification and thus provide potential advantages for PAR2 peptide design for in vitro and in vivo studies. The novel compounds described herein also serve as a starting point for structure activity relationship (SAR) design and are, for the fist time, evaluated via a unique high throughput in vitro physiological assay. Together these will lead to discovery of more potent agonists and antagonists of PAR(2).