From High-Throughput Screening to Target Validation: Benzo[]isothiazoles as Potent and Selective Agonists of Human Transient Receptor Potential Cation Channel Subfamily M Member 5 Possessing In Vivo Gastrointestinal Prokinetic Activity in Rodents.

Transient receptor potential cation channel subfamily M member 5 (TRPM5) is a nonselective monovalent cation channel activated by intracellular Ca increase. Within the gastrointestinal system, TRPM5 is expressed in the stoma, small intestine, and colon. In the search for a selective agonist of TRPM5 possessing in vivo gastrointestinal prokinetic activity, a high-throughput screening was performed and compound was identified as a promising hit. Hit validation and hit to lead activities led to the discovery of a series of benzo[]isothiazole derivatives. Among these, compounds and showed nanomolar activity and excellent selectivity (>100-fold) versus related cation channels. The in vivo drug metabolism and pharmacokinetic profile of compound was found to be ideal for a compound acting locally at the intestinal level, with minimal absorption into systemic circulation. Compound was tested in vivo in a mouse motility assay at 100 mg/kg, and demonstrated increased prokinetic activity.