Rhodanine derivatives as novel peroxisome proliferator-activated receptor γ agonists

Aim:To characterize the in vitro bioactivities of rhodanine derivatives as novelperoxisome proliferator-activated receptor (PPAR)γ modulators,based on a hit(SH00012671) identified during high-throughput screening (HTS) of a diversesynthetic compound library,and to preliminarily elucidate the structure-activityrelationship of this class of PPARγ agonists.Methods:Full-length PPARγ andretinoid X receptor α(RXRα),biotinylated PPAR response element (PPRE),[~3H]BRL49653 (rosiglitazone),and streptavidin-coated FlashPlate or microbeadswere used to measure the receptor-binding properties of various compounds basedon the scintillation proximity assay (SPA) technology.A recombinant PPRE vec-tor was transiently cotransfected with PPARγ and RXRα plasmids into the Africangreen monkey kidney (CV-1) cells,and the effects of BRL49653 and test com-pounds on transcription mediated by PPARγ were determined by examining lu-ciferase (reporter) responses.3T3-L1 cells were employed to determine whetherthe compounds facilitated adipogenesis upon PPARγ activation.Results:Of the16 000 samples screened with the SPA method,only 1 compound (SH00012671)displayed a similar binding affinity (Ki=186.7 nmol/L) to PPARγ as BRL49653,butit was inactive in the cell-based assays.A series of rhodanine derivatives weresynthesized based on the core structure of SH00012671 and 8 of them showedagonist activities in both cotransfection and pre-adipocyte differentiation assays.To reduce intrinsic cytotoxicities,the sulphur on the rhodanine was changed tooxygen.This alteration led to a decrease in receptor-binding affinities while modi-fied analogues generally maintained agonist efficacies in the cell-based assays.Of the analogues studied,compound 31 exhibited about 70% the efficacy exertedby BRL49653 in both cotransfection and pre-adipocyte differentiation assays.Conclusion:Through minor chemical modifications on the core structure of theinitial HTS hit,SH00012671 was transformed to possess both molecular (PPARγbinding) and cellular (adipogenesis) activities.The rhodanine derivatives re-ported here may represent a new scaffold in further understanding the molecularmechanism of agonism at PPARγ.