Discovery of P2Y₂ Receptor Antagonist Scaffolds through Virtual High-Throughput Screening

The human ATP- and UTP-activated P2Y₂ receptor (P2Y₂R) is a G_q protein-coupled receptor involved in several pathophysiological conditions including acute and chronic inflammation, cancer, and pain. Despite its potential as a novel drug target, only few P2Y₂R antagonists have been developed so far, all of which suffer from severe drawbacks. These include (i) high polarity due to one or several negative charges resulting in low oral bioavailability, (ii) metabolic instability and generally poor pharmacokinetic properties, and/or (iii) lack of selectivity, which limits their utility for in vitro and in vivo studies aimed at target validation. In search of new druglike scaffolds for P2Y₂R antagonists, we employed a structure-based virtual high-throughput screening approach utilizing the complex of a P2Y₂R homology model with one of the most potent and selective orthosteric antagonists described so far, AR-C118925 (10). After virtual screening of 3.2 million molecules, 58 compounds were purchased and pharmacologically evaluated. Several novel antagonist scaffolds were discovered, and their binding modes at the human P2Y₂R were analyzed by molecular docking studies. The investigated antagonists likely share a similar binding mode with 10 which includes accommodation of bulky, lipophilic groups in the putative orthosteric binding site of the P2Y₂R. The discovered scaffolds and the elucidated structure-activity relationships provide a basis for the development of future drug candidates for the P2Y₂R which have great potential as novel drugs.