Benzbromarone, an old uricosuric drug, inhibits human fatty acid binding protein 4 in vitro and lowers the blood glucose level in db/db mice.

AIM

Fatty acid-binding protein 4 (FABP4) plays an important role in maintaining glucose and lipid homeostasis. The aim of this study was to find new inhibitors of FABP4 for the treatment of type 2 diabetes.

METHODS

Human FABP4 protein was expressed, and its inhibitors were detected in 1,8-ANS displacement assay. The effect of the inhibitor on lipolysis activity was examined in mouse 3T3-L1 preadipocytes. The db/db mice were used to evaluate the anti-diabetic activity of the inhibitor. Molecular docking and site-directed mutagenesis studies were carried out to explore the binding mode between the inhibitor and FABP4.

RESULTS

From 232 compounds tested, benzbromarone (BBR), an old uricosuric drug, was discovered to be the best inhibitor of FABP4 with an IC50 value of 14.8 μmol/L. Furthermore, BBR (25 μmol/L) significantly inhibited forskolin-stimulated lipolysis in 3T3-L1 cells. Oral administration of BBR (25 or 50 mg/kg, for 4 weeks) dose-dependently reduced the blood glucose level and improved glucose tolerance and insulin resistance in db/db mice. Molecular docking revealed that the residues Ser55, Asp76, and Arg126 of FABP4 formed important interactions with BBR, which was confirmed by site-directed mutagenesis studies.

CONCLUSION

BBR is an inhibitor of FABP4 and a potential drug candidate for the treatment of type 2 diabetes and atherosclerosis.