Distinctive molecular inhibition mechanisms for selective inhibitors of human 11β-hydroxysteroid dehydrogenase type 1

The synthesis, X-ray co-crystal structures and kinetic analysis of two novel and potent small molecule inhibitors of 11β-HSD1 are reported. Structural and kinetic analyses demonstrate two distinctive molecular inhibition mechanisms for the two classes of inhibitors. 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) catalyzes the NADPH dependent interconversion of inactive cortisone to active cortisol. Excess 11β-HSD1 or cortisol leads to insulin resistance and metabolic syndrome in animal models and in humans. Inhibiting 11β-HSD1 activity signifies a promising therapeutic strategy in the treatment of Type 2 diabetes and related diseases. Herein, we report two highly potent and selective small molecule inhibitors of human 11β-HSD1. While compound 1, a sulfonamide, functions as a simple substrate competitive inhibitor, compound 2, a triazole, shows the kinetic profile of a mixed inhibitor. Co-crystal structures reveal that both compounds occupy the 11β-HSD1 catalytic site, but present distinct molecular interactions with the protein. Strikingly, compound 2 interacts much closer to the cofactor NADP + and likely modifies its binding. Together, the structural and kinetic analyses demonstrate two distinctive molecular inhibition mechanisms, providing valuable information for future inhibitor design.