Synthesis, characterization and cytotoxicity of a series of tetrachloridoplatinum(IV) complexes

Two platinum(IV) complexes, [Pt(4bt)Cl4] (4) and [Pt(dpyam)Cl4]·DMF (5) (where 4bt is 4,4′-bithiazole and dpyam is 2,2′-dipyridylamine) were prepared from the reaction of H2PtCl6·6H2O with 4,4′-bithiazole and 2,2′-dipyridylamine, respectively, in methanol. Both complexes were fully characterized and their structures were determined by the X-ray diffraction method. These complexes have a bidentate nitrogenous ligand with four chloride anions attached to a Pt(IV) metal in a distorted octahedral environment. These complexes along with three previously reported analogous complexes were used for in vitro cytotoxicity evaluation against four cultures, NIH-3T3, Caco-2, HT-29 and T47D by MTT assay. The methyl group position in the ligand plays an important role in the cytotoxicity of relevant compounds in different cultures. Interestingly, in some cases, the IC50 values of the new complexes were higher for normal cells but lower against cancer cells in comparison with cisplatin, especially in T47D (breast ductal carcinoma).