Platinum(II) chloride indenyl complexes: electrochemical and biological evaluation

Four platinum(II) complexes of general formula [PtCl(η1-C9H7)L2] [where L2 is 1,2-bis(diphenylphosphino)ethane (dppe) 1 or cycloocta-1,5-diene (cod) 3] and [PtCl2L2] (where L2 is dppe 2 or cod 4) were studied. Inhibition growth assays on human tumor cell lines evidenced for 1 and 3 an antiproliferative effect and, interestingly, the cytotoxic effect exerted by 1 is similar to that of cisplatin. Electrochemical and NMR measurements allowed us to determine the structural and redox properties. Investigation of the mechanism of action responsible for the cytotoxicity demonstrated a weak capacity of interacting with DNA. Some experiments performed on rat liver mitochondria indicate that 1 acts as an inducer of the mitochondrial permeability transition, thus leading to the release of proapoptotic factors, such as cytochrome c and apoptosis-inducing factor.