Synthesis, characterization, lipophilicity and cytotoxic properties of novel bis(carboxylato)oxalatobis(1-propylamine)platinum(IV) complexes

Abstract A series of novel bis(carboxylato)oxalatobis(1-propylamine)platinum(IV) complexes as well as an ethylamine analog were synthesized. The compounds are either symmetrical with both axial ligands consisting of monoesters of succinic acid, or unsymmetrical, with one axial ligand being acetate. The compounds were characterized in detail by elemental analysis, mass spectrometry and multinuclear (1H, 13C, 15N, 195Pt) NMR spectroscopy. The reduction behavior was followed by NMR spectroscopy, while lipophilicity was determined by analytical reversed-phase HPLC measurements. The capacity of inhibiting proliferation of the human cancer cell lines A549 (non-small cell lung cancer), CH1(PA-1) (ovarian teratocarcinoma) and SW480 (colon carcinoma) was evaluated by the MTT assay. In the most sensitive cell line CH1(PA-1), all compounds exhibited IC50 values in the lower µM range. In general, the IC50 values decreased with increasing lipophilicity within the two compound series. Nevertheless, replacing one of the succinic ester ligands with acetate has a rather marginal impact on antiproliferative activity and is hardly disadvantageous.