Rational Design and Synthesis of Reversible Covalent PPARγ Antagonistic Ligands Inhibiting Ser273 Phosphorylation

Peroxisome proliferator-activated receptor gamma (PPARγ) has been a major therapeutic target for the treatment of type 2 diabetes. However, the use of PPARγ-targeting drugs such as rosiglitazone and pioglitazone has significantly declined due to adverse effects caused by their classical transcriptional agonism. Meanwhile, blocking the obesity-induced phosphorylation of PPARγ at Ser273 by Cdk5 has been proposed as the key to developing insulin-sensitizing effects of PPARγ-targeting drugs. In this study, we rationally designed and synthesized selective PPARγ phosphorylation inhibitor through a crystal structure-based approach. During this process, we observed a distinct degradation pattern of the anilinic cyanoacrylamide moiety via the spontaneous retro-aldol reaction. Thus, we developed a novel reversible covalent inhibitor of PPARγ phosphorylation, SB1495, containing aliphatic cyano-acrylamide, through systematic structural modification, in silico docking studies, time-dependent monitoring of stability in aqueous media, and in vitro kinase assay. We also demonstrated its inhibitory activity on PPARγ phosphorylation without classical transactivation in a cellular system as well as in an animal model.