DNA binding studies of a series of cis-[Pt(Am)2X2] complexes (Am = inert amine, X = labile carboxylato ligand)

A series of platinum(II) complexes of formulae cis-[Pt(Am)2X2] (where Am represents an inert amine and X a labile (carboxylato) ligand) have been prepared and characterized by elemental analysis, ESI-MS, IR and 1H NMR spectroscopy. The single-crystal molecular structures were determined for cis-[Pt(opea)(cbdca-2H)], cis-[Pt(hmpy)(cbdca-2H)], cis-[Pt(NH3)2(bzmal-2H)] and cis-[Pt(hmpy)(μ-dcch-2H)2] (where opea is picolylamine, hmpy represents 4-hydroxymethylpyridine, cbdca-2H, is 1,1-cyclobutanedicarboxylate anion, bzmal-2H stands for benzylmalonate anion and dcch-2H is trans-1,2-cyclohexanedicarboxylate anion). The interaction of all compounds with DNA was investigated with different techniques: viscosity measurements and emission fluorescence spectroscopy were used to investigate the changes induced by the binding of the platinum compounds to calf-thymus DNA, while atomic force microscopy and electrophoretic mobility allowed evaluating the potential alterations of pBR322 plasmid DNA. The cytotoxic behavior of the platinum compounds on human leukemia HL-60 tumor cell lines was also examined.