Synthesis and characterization of new water-soluble organometallic complexes of the type [PtL(h1-C2H4OMe)(N^N)] (L = NH3, DMSO; N^N = dinitrogen ligand) with potential antitumor activity

Since the discovery of the antitumor activity of cisplatin, many studies have been devoted to understanding the relation between structure of platinum compounds and their antitumor activity. Several investigations on cisplatin analogues demonstrated that their effectiveness could be greatly improved by substituting the labile chlorido ligands with other leaving groups, giving a 2nd generation platinum drugs (e.g. carboplatin, nedaplatin, etc.). A 3rd generation could be obtained by replacement of both ammonia and chlorido ligands of cisplatin with different ligands (e.g. oxaliplatin, heptaplatin, etc.). The here studied new organometallic compounds belong to this last category. We synthesized complex precursors of type [PtCl(1-C2H4OMe)(N^N)], 3, by using a previously reported procedure consisting in the reaction of a dinitrogen ligand with the Zeise’s salt in basic methanol. Reaction of the neutral complex 3 with excess NH3 or DMSO in water solution, gave the final [Pt(NH3)(h1-C2H4OMe)(N^N)]+, 4’, or [Pt(DMSO)(h1-C2H4OMe)(N^N)]+, 4’’, complexes, respectively. The citotoxic activity of such complexes were studied in comparison with cisplatin. Preliminary experiments on different cell lines showed a relevant cytotoxic activity for complex 4’’ differently from 4’, when N^N = 1,10-phenanthroline.