Absolute Configuration and Biological Properties of Enantiomers of CFTR Inhibitor BPO-27

Abstract

We previously reported benzopyrimido-pyrrolo-oxazinedione (BPO) inhibitors of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel and showed their efficacy in a model of polycystic kidney disease. Here, we separated the enantiomers of lead compound BPO-27, (<b>1</b>), which contains a single chiral center, and determined their absolute configuration, activity and metabolic stability. Following separation by chiral supercritical fluid chromatography, the <i>R</i> enantiomer, as determined by x-ray crystallography, inhibited CFTR chloride conductance with IC₅₀ ~ 4 nM, while <i>S</i> enantiomer was inactive. In vitro metabolic stability in hepatic microsomes showed both enantiomers as stable, with <5 % metabolism in 4 h. Following bolus interperitoneal administration in mice, serum (<i>R</i>)-<b>1</b> decayed with t_1/2 ~ 1.6 h and gave sustained therapeutic concentrations in kidney.