Emodin, a natural product, selectively inhibits 11β-hydroxysteroid dehydrogenase type 1 and ameliorates metabolic disorder in diet-induced obese mice

BACKGROUND AND PURPOSE 11 beta-Hydroxysteroid dehydrogenase type 1 (11 beta-HSD1) is an attractive therapeutic target of type 2 diabetes and metabolic syndrome. Emodin, a natural product and active ingredient of various Chinese herbs, has been demonstrated to possess multiple biological activities. Here, we investigated the effects of emodin on 11 beta-HSD1 and its ability to ameliorate metabolic disorders in diet-induced obese (DIO) mice. EXPERIMENTAL APPROACH Scintillation proximity assay was performed to evaluate inhibition of emodin against recombinant human and mouse 11 beta-HSDs. The ability of emodin to inhibit prednisone- or dexamethasone-induced insulin resistance was investigated in C57BL/6J mice and its effect on metabolic abnormalities was observed in DIO mice. KEY RESULTS Emodin is a potent and selective 11 beta-HSD1 inhibitor with the IC50 of 186 and 86 nM for human and mouse 11 beta-HSD1, respectively. Single oral administration of emodin inhibited 11 beta-HSD1 activity of liver and fat significantly in mice. Emodin reversed prednisone-induced insulin resistance in mice, whereas it did not affect dexamethasone-induced insulin resistance, which confirmed its inhibitory effect on 11 beta-HSD1 in vivo. In DIO mice, oral administration of emodin improved insulin sensitivity and lipid metabolism, and lowered blood glucose and hepatic PEPCK, and glucose-6-phosphatase mRNA. CONCLUSIONS AND IMPLICATIONS This study demonstrated a new role for emodin as a potent and selective inhibitor of 11 beta-HSD1 and its beneficial effects on metabolic disorders in DIO mice. This highlights the potential value of analogues of emodin as a new class of compounds for the treatment of metabolic syndrome or type 2 diabetes.