Synthesis, structures and in vitro cytotoxicity of some platinum(II) complexes containing thiocarbamate esters

The thiocarbamate esters 4-RC6H4NHC(S)OMe (R = H, Cl, OMe, NO2, Me) react with cis-[PtCl2(PTA)2] (PTA = 1,3,5-triaza-7-phosphaadamantane) in the presence of base to afford the platinum(II) complexes trans-[Pt{SC(OMe)NC6H4R}2(PTA)2] (R = H, Cl, OMe, NO2, Me) in high yields. The complexes were fully characterised spectroscopically and, in case of the NO2 derivate, by X-ray crystallography. Cytotoxicity of these complexes was studied in vitro in four human cancer cell lines (CH1, HT29, A549, SK-OV-3) using the MTT assay. The results show that the Cl substituted derivate is the most potent of these compounds in vitro. Moreover, this derivative is capable of partially circumventing primary cisplatin resistance in ovarian and colon carcinoma cells.