A series of cationic dinuclear p-cymene ruthenium trithiophenolato complexes of the type [(g 6-p-MeC 6 H 4 Pr i) 2 Ru 2 (SC 6 H 4-p-X) 3 ] ? (1 X is H, 2 X is Me, 3 X is Ph, 4 X is Br, 5 X is OH, 6 X is NO 2 , 7 X is OMe, 8 X is CF 3 , 9 X is F, 10 X is Pr i , 11 X is Bu t) have been synthesized from the reaction of [(g 6-p-MeC 6 H 4 Pr i)-RuCl 2 ] 2 with the corresponding thiol, isolated as the chloride salts, and further studied for their electrochemical properties, cytotoxicity towards human ovarian cancer cells, and catalytic activity for glutathione (GSH) oxidation. Complex 1 was also compared with the benzene and hexamethylbenzene analogues [(g 6-C 6 H 6) 2 Ru 2 (SC 6 H 5) 3 ] ? (12) and [(g 6-C 6 Me 6) 2 Ru 2 (SC 6 H 5) 3 ] ? (13). The most active compound [11]Cl was structurally studied by single-crystal X-ray diffraction analysis. The concentrations corresponding to 50 % inhibition of cancer cell growth (IC 50 values) in the A2780 and A2780cisR cell lines of these complexes except for 6 were in the submicromolar range, complex 11 showing an IC 50 value of 0.03 lM in both cell lines. The high in vitro anticancer activity of these complexes may be at least partially due to their catalytic potential for the oxidation of GSH, although there is no clear correlation between the IC 50 values and the turnover frequencies at about 50 % conversion. However, the cytotoxicity is tentatively correlated to the physicochemical properties of the compounds determined by the electronic influence of the substituents X (Hammett constants r p) and the lipophilicity of the thiols p-XC 6 H 4 SH (calculated log P parameters).

The effects of 18 dinuclear thiolato-bridged arene ruthenium complexes (1 monohiolato compound, 4 dithiolato compounds, and 13 trithiolato compounds), originally designed as anticancer agents, on the apicomplexan parasite grown in human foreskin fibroblast (HFF) host cells were studied. Some trithiolato compounds exhibited antiparasitic efficacy at concentrations of 250 nM and below. Among those, complex 1 and complex 2 inhibited proliferation with 50% inhibitory concentrations (ICs) of 34 and 62 nM, respectively, and they did not affect HFFs at dosages of 200 μM or above, resulting in selectivity indices of >23,000. The ICs of complex 9 were 1.2 nM for and above 5 μM for HFFs. Transmission electron microscopy detected ultrastructural alterations in the matrix of the parasite mitochondria at the early stages of treatment, followed by a more pronounced destruction of tachyzoites. However, none of the three compounds applied at 250 nM for 15 days was parasiticidal. By affinity chromatography using complex 9 coupled to epoxy-activated Sepharose followed by mass spectrometry, translation elongation factor 1α and two ribosomal proteins, RPS18 and RPL27, were identified to be potential binding proteins. In conclusion, organometallic ruthenium complexes exhibit promising activities against , and the potential mechanisms of action of these compounds as well as their prospective applications for the treatment of toxoplasmosis are discussed.

ABSTRACT:The highly cytotoxic diruthenium complex [(p-MeC 6 H 4 Pr i ) 2 Ru 2 (SC 6 H 4 -p-Me) 3 ] + (1), water-soluble as the chloride salt, is shown to efficiently catalyze oxidation of the thiols cysteine and glutathione to give the corresponding disulfides, which may explain its high in vitro anticancer activity.

A new series of cationic dinuclear p-cymene ruthenium complexes bridged by three thiophenolato ligands containing various substituents mainly in meta and ortho positions, [(Z 6 -p-MeC 6 H 4 Pr i ) 2 Ru 2 (m 2 -SR) 3 ] + (R = 3-C 6 H 4 Me: 1; R = 3-C 6 H 4 OMe: 2; R = 3-C 6 H 4 OEt: 3; R = 3-C 6 H 4 CF 3 : 4; R = 3-C 6 H 4 NH 2 : 5; R = 3-C 6 H 4 Cl: 6; R = 2-C 6 H 4 Me: 7; R = 2-C 6 H 4 OMe: 8; R = 2-C 6 H 4 Pr i : 9; R = 2-C 6 H 4 CF 3 : 10; R = npt: 11 (npt = 2-naphthyl); R = mco: 12 (mco = 4-methylcoumarinyl); R = 3,5-C 6 H 3 Me 2 : 13; R = 3,5-C 6 H 3 (CF 3 ) 2 : 14; R = 3,5-C 6 H 3 Cl 2 :15; R = 3,4-C 6 H 3 (OMe) 2 : 16), have been prepared from the reaction of the neutral p-cymene diruthenium dichloride dimer, [(Z 6 -p-MeC 6 H 4 Pr i ) 2 Ru 2 Cl 4 ], with the corresponding thiophenol RSH. All cationic complexes have been isolated as their chloride salts and fully characterized by spectroscopic and analytical methods.The molecular structures of 10 and 15 have been solved by a single-crystal X-ray structure analysis of [10]Cl and [15]Cl, which show that the two ruthenium atoms adopt a pseudo-octahedral geometry without a metal-metal bond in accordance with the noble gas rule. All complexes are highly cytotoxic towards human ovarian cancer cells, the IC 50 values being mostly in the nanomolar range. Complex 9 shows the highest cytotoxicity with an IC 50 value of 0.03 mM towards the A2780 cell line and the cisplatin-resistant mutant A2780cisR. The cytotoxicity of these complexes, which belong to the most active ruthenium anticancer compounds reported so far, can be correlated with the lipophilicity of the corresponding thiols. In comparison with the previous series, the results demonstrate that the positions of the substituents in the thiopenolato bridges are not as important as the nature of the substituents, alkyl substituents being the best ones in line with their lipophilic character.

Dinuclear ruthenium complexes inhibit N. caninum and specifically target the parasite mitochondria.