Interactions of the platinum(II) and palladium(II) complexes coordinated with a ligand containing a sulfur atom with DNA and DNA-constituting nucleosides

cis-Diamminedichloroplatinum(II) complex (cis-DDP) is widely utilized as an anticancer agent for clinical treatments of various cancers. It has been repeatedly confirmed that cis-DDP binds specifically to DNA in cancer cells to inhibit the replication of the DNA. Therefore, many investigations have been made concerning novel platinum complexes with various carrier ligands to be used as anticancer agents. However, the studies on the plantinum group complexes coordinated with a ligand containing sulfur atoms have not been reported yet. In this paper, tiovel platinum group complexes, dichloro(2-aminoethylsulfonyl)platinum (II) and dichloro(2-aminoethylsulfonyl)palladium(II), were synthesized. The investigations were also carried out on the cytostatic-cytotoxic activities, the interactions between the platinum group complexes and DNA, as well as DNA constituent nucleosides by analyzing the UV spectra, UV difference spectra and the liberation concentration of the chloride ions from the platinum group complexes. The palladium complex was found to exhibit a specific cytostatic-cytotoxic activity, as well as the platinum complex. In the interactions of the platinum group complexes with DNA and the nucleosides, the platinum complex was suggested to be specifically different from the palladium complex in its binding to nucleosides.