The goal of our study was to potentiate the effects of the ((R,R)-trans-1,2-diaminocyclohexane)-platinum(II) fragment [(
DACH)Pt], known for its cytotoxic properties, either with
tamoxifen (Tam), the most widely used
antiestrogen in the treatment of
hormone-dependent breast
cancers, or with its active metabolite
hydroxytamoxifen (hydroxy-Tam). We coupled Tam or hydroxy-Tam derivatives bearing a malonato group at the para position of the beta aromatic ring with the (
DACH)Pt fragment. The malonato-Tam and malonato-hydroxy-Tam compounds were prepared through McMurry coupling of the appropriate
ketones. The presence of the
malonate group resulted in a pronounced stereospecificity in the reaction, since malonato-Tam was obtained only as the Z isomer, while malonato-hydroxy-Tam was obtained as an 80/20 E/Z mixture. Attribution of the isomeric structures was achieved by 2D NMR spectroscopy. The
platinum complexes (
DACH)Pt-malonato-Tam and (
DACH)Pt-malonato-hydroxy-Tam were then prepared by coupling the
barium salts derived from the malonato-Tam and malonato-hydroxy-Tam with the
nitrate derived from (
DACH)PtCl(2). Study of the biochemical properties of these two
platinum complexes showed that, while the hydroxy-Tam complex is satisfactorily recognized by the
estrogen receptor (relative binding affinity, RBA=6.4 %), the Tam complex is less well recognized (RBA=0.5 %). The effects of these complexes on two
hormone-dependent
breast cancer cell lines (MCF7 and MVLN) were studied in vitro. Both complexes showed an antiproliferative effect on MCF7 cells, and an antiestrogenic effect on MVLN cells. The observed effects appear to be essentially antihormonal, since incorporation of the (
DACH)Pt fragment into the
tamoxifen skeleton did not cause an increase in the cytotoxicity of the complexes.