The triphenyltin(VI) complexes of NSAIDs and derivatives. Synthesis, crystal structure and antiproliferative activity. Potent anticancer agents

The novel triphenyltin(IV) esters of flufenamic acid (1), Hflu, [Ph₃Sn(flu)] (2), and of [2-(2,3-dichlorophenylamino)benzoic acid] (3), Hdcpa, [Ph₃Sn(dcpa)] (4) have been structurally characterized by means of vibrational and ¹H, ¹³C NMR spectroscopic studies. The crystal and molecular structures of [SnPh₃(dcpa)(DMSO)] 4a are described. The molecular structure of 4a reveals that the Sn atom has a distorted trigonal bipyramidal coordination geometry with equatorial phenyl groups and the carboxylate and dimethylsulfoxide oxygen atoms occupying axial positions. The crystal structure of 4a is self-assembled by C-H---π and π-π stacking interactions. The in vitro cytotoxic activity of 1-4 and of the related non-steroidal anti-inflammatory drugs, NSAIDs, [2-(2,6-dimethylphenylamino)benzoic acid], Hdmpa (5), [Ph₃Sn(dmpa)] (6), [2-(2,3-dimethylphenylamino)benzoic acid], mefenamic acid, Hmef (7) and [Ph₃Sn(mef)] (8) has been evaluated against the cancer cell lines MCF-7, T-24, A-549 and L-929. The ligands exhibited very poor cytotoxic activity against the four cancer cell lines. Complex 6 exhibits the highest activity and selectivity against A-549 and MCF-7 cancer cell lines and complex 8 the highest activity and selectivity against T-24 cancer cell line. The cytotoxic results indicate that coupling of Hdmpa and Hmef with R₃Sn(IV) metal center results in complexes with important biological properties and remarkable cytotoxic activity, since they display IC₅₀ values in a μΜ range better to that of the antitumor drug cis-platin. Complexes 6 and 8 are considered as excellent antitumor compounds and the results of this study represent the discovery of triphenyltin(IV)esters as a potential novel class of anticancer agents.