Preparation, characterization and antileukemic properties of diaminemalonatoplatinum(II) complexes tethered to ferrocene

In search for new antitumor agents with target specificity we have prepared four new complexes in which diaminemalonatoplatinum(II) moieties are covalently tethered to ferrocene - and organ specific biological carrier. The four PtAm₂[(ferrocenemethyl)propanedioic acid] complexes (where Am₂(NH₃)₂, bis(aminocyclobutane), cis- and trans-1,2-diaminocyclohexane) were characterized by ¹⁹⁵pt NMR spectroscopy and by elemental analysis. Their activity was assessed in vitro against P388 leukemia cells. They showed considerable activity (ED₅₀ in the 5-45 μM range) though to a smaller extent than cis-diamminedichloroplatinum(II). They are, however, more active than the previously reported complexes in which a bis(phosphinecatecholato)platinum(II) moiety was tethered to ferrocene or to ruthenocene.