Design, Synthesis, and Structure-Activity Relationship Studies of Novel 2,4,6-Trisubstituted-5-pyrimidinecarboxylic Acids as Peroxisome Proliferator-Activated Receptor γ (PPARγ) Partial Agonists with Comparable Antidiabetic Efficacy to Rosiglitazone

A series of novel 2,4,6-trisubstitutedpyrimidine-5-carboxylic acid derivatives were designed and synthesized with the intent of producing a peroxisome proliferator-activated receptor gamma (PPAR gamma) partial agonist for antidiabetic agents. A pharmacophore-driven approach of in-house screening identified compound 7, which led to the identification of compound 9 featuring a 2,4,6-trisubstituted pyrimidine-5-carboxylic acid core. Structure activity relationship studies of 9 resulted in identifying 4,6-bisbenzylthio-2-methylthiopyrimidine-5-carboxylic acid (50) as the most attractive of all the screened compounds. The X-ray cocrystal structure of 50 bound on PPAR gamma revealed that the key hydrogen bond interactions, which are not related to the activation function 2 (AF-2) site, are different from those of the full agonist. Compound 50 showed typical PPAR gamma partial agonist properties in the PPAR gamma-GAL4 functional assay and weaker differentiation of adipocytes in 3T3-L1 cells than observed with rosiglitazone. Furthermore, 50 displayed comparable antidiabetic efficacy with rosiglitazone in db/db mice, although its potency is 10-fold weaker than that of rosiglitazone.