Discovery of uracil-based antagonists and fluorescent ligands of the P2Y₂ receptor

Antagonism of purinergic P2Y₂ receptors offers potential benefits in the treatment of inflammatory diseases, neurodegenerative disorders, and cancer. Despite the promising preclinical potential, only a limited number of potent and selective non-nucleotide P2Y₂R antagonists are known, including AR-C118925, which has been extensively used to study inhibition of the P2Y₂R. However, unfavorable physicochemical properties and the presence of a reactive and photo-unstable 4-thiouracil moiety have limited their preclinical progress. Through a fragment recombination approach utilizing P2Y₂R privileged fragments to explore non-additive SAR trends in combination with molecular docking studies, we discovered a series of potent uracil-based P2Y₂R antagonists, such as compound 26a (pK_i (whole cells) 6.55 ± 0.05). Molecular docking of 26a led to rationalization of the unexpected affinity for 26a, and led to the identification of new stable, uracil-based fluorescent ligands targeting the P2Y₂R.