Synthesis, DNA binding and cytotoxicity of isohelical DNA groove binding platinum complexes

The two platinum complexes [(Pt(dien))2 mu -dpzm](4+) and trans-[Pt(NH3)(2) (mu -dpzm)(2)](2+)(dpzm = 4,4 ' -dipyrazolylmethane) have been synthesized and their DNA binding and cytotoxicity studied in order to evaluate the pot ential of square-planar platinum complexes as DNA groove binding anti-cance r agents. H-1-NMR spectroscopy was used to study the binding of both metal complexes to the dodecanucleotide d(CGCGAATTCGCG)(2), For both platinum com plexes, a considerable number of intermolecular NOE contacts were observed in NOESY spectra of the platinum complex bound dodecanucleotide. The NOE da ta demonstrated that each platinum complex bound in the minor groove at the central AATT region, Neither platinum complex appeared to induce any major DNA conformation change. In vitro cytotoxicity studies in the murine leuka emia cell lines L1210 and L1210/cisR showed that trans[Pt(NH3)(2)(mu -dpzm) (2)](2+) had some activity (IC50: 64 and 32 muM respectively) while the [(P t(dien))2 mu -dpzm](4+) complex showed no activity at all (> 200 muM). The results indicate that it may be possible to synthesize platinum complexes t hat are useful as groove binding agents in the treatment of cancer.