Palladium(II)‐Imidoyl Complexes: A New Piece in the Puzzle of Organopalladium Anticancer Agents

Our search of new organopalladium compounds able to promote an effective antiproliferative action towards ovarian cancer cells continues. In this paper we have examined for the first time the anticancer activity of palladium imidoyl complexes, for which two different types of phosphines have been chosen as ancillary ligands: i) PTA and DAPTA to take advantage from their solubility in aqueous environment, and ii) dppf for combining the action of the Pd-imidoyl fragment with that, well-known, of ferrocene. The synthetic protocols as well as the exhaustive characterisation of the complexes through spectroscopic and diffractometric methods are described. In vitro tests carried out to assess the cytotoxicity of the new compounds towards two ovarian cancer cell lines (one cisplatin sensitive and the other cisplatin resistant) have revealed an interesting effect of the halide coordinated to the palladium centre (halogen effect). Moreover, all complexes have shown the same activity against the cisplatin-sensitive (A2780) and cisplatin-resistant (A2780cis) cell lines, suggesting a different mode of action with respect to the “classical” platinum-based drugs. Finally, a selection of the most active compounds has shown an interesting selectivity towards ovarian cancer cells.