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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 synthesis, characterization, photophysical and biological properties of 13 new conjugate coumarin-diruthenium(II)•arene complexes against Toxoplasma gondii are presented. For all conjugate organometallic unit/coumarins, an almost complete loss of fluorescence efficacy was observed. However, the nature of the fluorophore, the type of bonding, the presence and length of a linker between the coumarin dye and the ruthenium(II) moiety, and the number of dye units influenced their biological properties. The in vitro activity against a trans-genic T. gondii strain grown in human foreskin fibroblasts (HFF) leads to IC 50 values for T. gondii β-gal from 105 to 735 nM. Of note is that nine compounds displayed lower IC 50 than the standard drug pyrimethamine. One compound applied at its IC 50 did not affect B-cell proliferation but had an impact on Tcell proliferation in murine splenocyte cultures. Transmission electron microscopy of T. gondii β-gal-infected HFF showed that treatment predominantly affected the parasites' mitochondrion.

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.