Synthesis and characterization of a small molecule CFTR chloride channel inhibitor

A thiazolidinone CFTR inhibitor (CFTRinh-172) was synthesized by a three-step procedure with trifluromethylaniline as the starting material. The synthesized CFTR inhibitor was characterized structurally by means of H-1 NMR and functionally in a CFTR-expressing cell line FRT/hCFTR/EYFP-H148Q by both fluorescent and electrophysiological methods. A large amount (100 g) of high-quality small molecule thiazolidinone CFTR chloride channel inhibitor 9 CFTRinh-172, can be produced with this simple three-step synthetic procedure. The structure of the final product 2-thioxo-3-(3-trifluromethylphenyl)-5-[4-carboxyphenylmethylene]-4-thiazolidinone was confirmed by H-1 NMR. The overall yield was 58% with a purity over 99% as analyzed by HPLC. The synthesized CFTRinh-172 specifically inhibited CFTR chloride channel function in a cell-based fluorescence assay (K-d approximate to 1.5 mumol/L) and in a Ussing chamber-based short-circuit current assay (K-d approximate to 0.2 mumol/L). indicating better quality than that of the commercial combinatorial compound. The synthesized inhibitor is nontoxic to cultured cells at a high concentration and to mouse at a high dose. The synthetic procedure developed here can be used to produce a large amount of the high-quality CFTRinh-172 suitable for antidiarrheal studies and for creation of cystic fibrosis models in large animals. The procedure can be used to synthesize radiolabled CFTRinh-172 for in vivo pharmacokinetics studies.