Cationic Carboxylate and Thioacetate Ruthenium(II) Complexes: Synthesis and Cytotoxic Activity Against Anaplastic Thyroid Cancer Cells
The cationic acetate ruthenium complex [Ru(η1-OAc)(CO)(dppb)(phen)]OAc (1) is easily prepared in 83% yield from [Ru(η1-OAc)(η2-OAc)(CO)(dppb)] (dppb = 1,4-bis(diphenylphosphino)butane) and 1,10-phenanthroline (phen) in MeOH. The derivative 1 undergoes easy substitution of the coordinated acetate by reaction with NaOPiv, KSAc, KSCN in MeOH, affording the corresponding complexes [RuX(CO)(dppb)(phen)]X (X = OPiv, 2; SAc, 3; NCS, 4), whereas reaction with NaCl and NH4PF6 gives [RuCl(CO)(dppb)(phen)]PF6 (5). The derivatives 1-5 display high stability in chlorinated and polar solvents in air for days. The carboxylate complexes 1 and 2 show high solubility in water, affording easy exchange of the coordinated carboxylate by water and other ligands (CH3CN, glutathione). The cationic complexes 1-5, compared to Cisplatin, display strong cell viability decrease on two human anaplastic thyroid cancer cell lines (SW1736 and 8505C), ranging from 3.10 µM to 0.09 µM EC50 values. The most active compounds 1-3 show a marked increment of apoptosis and decrease of cancer cell aggressiveness, making them promising candidates for further evaluation studies.