Structural characterization and pharmacodynamic effects of an orally active 11 beta-hydroxysteroid dehydrogenase type 1 inhibitor

11 beta-Hydroxysteroid dehydrogenase type 1 regulates glucocorticoid action and inhibition of this enzyme is a viable therapeutic strategy for the treatment of type 2 diabetes and the metabolic syndrome. Here, we report a potent and selective 11 beta-hydroxysteroid dehydrogenase type 1 inhibitor with a binding mode elucidated from the co-crystal structure with the human 11 beta-hydroxysteroid dehydrogenase type 1. The inhibitor is bound to the steroid-binding pocket making contacts with the catalytic center and the solvent channel. The inhibitor binding is facilitated by two direct hydrogen bond interactions involving Tyrosine183 of the catalytic motif Tyr-X-X-X-Lys and Alanine172. In addition, the inhibitor makes many hydrophobic interactions with both the enzyme and the co-factor nicotinamide adenine dinucleotide phosphate (reduced). In lean C57BL/6 mice, the compound inhibited both the in vivo and ex vivo 11 beta-hydroxysteroid dehydrogenase type 1 activities in a dose-dependent manner. The inhibitory effects correlate with the plasma compound concentrations, suggesting that there is a clear pharmacokinetic and pharmacodynamic relationship. Moreover, at the same doses used in the pharmacokinetic/pharmacodynamic studies, the inhibitor did not cause the activation of the hypothalamic-pituitary-adrenal axis in an acute mouse model, suggesting that this compound exhibits biological effects with minimal risk of activating the hypothalamic-pituitary-adrenal axis.