Tryptophan-containing dipeptide derivatives as potent PPARgamma antagonists: design, synthesis, biological evaluation, and molecular modeling.

The discovery of peroxisome proliferator-activated receptor gamma (PPARgamma) antagonists (also termed "selective PPARgamma modulators, SPPARgammaM") is now of a great interest in the treatment of diabetes and obesity. The structure of compound 1a (G3335, Fig. 1), a novel class of PPARgamma antagonist, is entirely different from that of other reported PPARgamma antagonists. A series of 35 novel analogues (1b-l, 9a-d, 13a-t) were designed, synthesized and evaluated against the agonistic effects exerted by rosiglitazone. These results indicated that most functional groups of 1a were conserved, and six new compounds (1b, 1c, and 9a-d) exhibited strong PPARgamma antagonistic activities (IC(50) values of 5.2-25.8 microM) against 10 microM rosiglitazone in the promotion of the PPARgamma-LBD-CBP (ligand-binding domain and cAMP-response-element binding protein) interaction as investigated by yeast two-hybrid technology based assay. Molecular modeling studies for compounds 1a-d, 1h, 9c-d, and 13a were also presented.