New mononuclear and homodinuclear Pt(ii) complexes with heterocyclic nitrogen chelates: synthesis, characterization, intercalating ability and in vitro cytotoxic activity evaluation.

A series of new mononuclear and dinuclear platinum(ii) compounds based on two bipyridyl systems, linked by an alkyl chain {1,2-bis[4-(4'-methyl-2,2'-bipyridinyl)]ethane, L2, (a), and 1,6-bis[4-(4'-methyl-2,2'-bipyridinyl)]hexane, L6, (b)} have been synthesized and characterized by IR and multinuclear and multidimensional NMR spectroscopy. The coordination sphere of the complexes, designed to give intercalating and/or covalent interactions with DNA, is completed only by exchangeable (Cl(-), I(-) or H(2)O) and/or not leaving (chelate ethylenediamine, en) saturating ligands. Quenching of the DNA-ethidium fluorescence was performed in order to verify the intercalating capability of the water soluble compounds. Furthermore, the in vitro cytotoxicity of all water soluble complexes has been assessed with respect to cisplatin on platinum-sensitive human endometrium (HeLa) and platinum-resistant human breast (MCF-7) cancer cell lines.