Abstract
The P2Y(2) receptor (P2Y(2)R) is a target for diseases including cancer, idiopathic pulmonary fibrosis, and atherosclerosis. However, there are insufficient P2Y(2)R antagonists available for validating P2Y(2)R function and future drug development. Evaluation of how (R)-5-(7-chloro-2-((2-ethoxyethyl)amino)-4H-benzo[5,6]cyclohepta[1,2-d]thiazol-4-yl)-1-methyl-4-thioxo-3,4-dihydropyrimidin-2(1H)-one, a previously published thiazole-based analogue of AR-C118925, binds in a P2Y(2)R homology model was used to design new P2Y(2)R antagonist scaffolds. One P2Y(2)R antagonist scaffold retained millimolar affinity for the P2Y(2)R and upon further functionalization with terminal carboxylic acid groups affinity was improved over 100-fold. This functionalized P2Y(2)R antagonist scaffold was employed to develop new chemotype P2Y(2)R fluorescent ligands, that were attainable in a convergent five-step synthesis. One of these fluorescent ligands demonstrated micromolar affinity (pK (d) = 6.02 ± 0.12, n = 5) for the P2Y(2)R in isolated cell membranes and distinct pharmacology from an existing P2Y(2)R fluorescent antagonist, suggesting it may occupy a different binding site on the P2Y(2)R.