Novel Homoleptic and Heteroleptic Pt(II) β-oxodithiocinnamic ester Complexes: Synthesis, Characterization, Interactions with 9-methylguanine and Antiproliferative Activity

Three new series of homoleptic and heteroleptic platinum(II) beta-oxodithiocinnamic ester complexes, [Pt(L1-L9)(2)], [Pt(L1-L9)(DMS)Cl] and [Pt(L1-L9)(DMSO)Cl], were synthesized and characterized using elemental analysis, mass spectrometry, and different NMR spectroscopy (H-1, C-13{H-1} and Pt-195). The beta-oxodithiocinnamic esters coordinate towards the platinum(II) centre as O,S-bidentate chelating ligands. The structures of HL3, [Pt(L2)(2)], [Pt(L6)(DMS)Cl] as well as [Pt(L2)(DMSO)Cl] have been confirmed through the X-ray crystallography, where the platinum(II) complexes exhibit a slightly distorted square planar geometry. In this article, we also investigated the solvolysis of three representative Pt(II) complexes, as well as the interaction with 9-methylguanine as a DNA model system, by utilizing the LC-ESI-MS technique. A selection of the complexes was assessed for their use as anticancer agents, and cytotoxicity assays with these complexes showed modest toxicity on both Cisplatin sensitive and resistant ovarian cancer cell lines. However, the compounds cytotoxicity was not affected by the Cisplatin resistance mechanisms and a specific selection of the ligands may modify the cell line specificity.