Highly cytotoxic trithiophenolatodiruthenium complexes of the type [(?6-p-MeC6H4Pri)2Ru2(SC6H4-p-X)3]+: synthesis, molecular structure, electrochemistry, cytotoxicity, and glutathione oxidation potential

A series of cationic binuclear areneruthenium tris(arenethiolato)-bridged complexes [(?6-p-cymene)2Ru2(?-SC6H4-p-X)3]+ (1-11; X = H, Me, Ph, Br, OH, NO2, OMe, CF3, F, iPr, tBu) were prepd. by complexation of the chloride-bridged dimer [(?6-p-cymene)2Ru2(?-Cl)2Cl2] with the corresponding thiols, isolated as the chloride salts, and further studied for their electrochem. properties, cytotoxicity towards human ovarian cancer cells, and catalytic activity for glutathione (GSH) oxidn. Complex 1 was also compared with the benzene and hexamethylbenzene analogs [(?6-C6H6)2Ru2(?-SC6H5)3]+ (12) and [(?6-C6Me6)2Ru2(?-SC6H5)3]+ (13). The most active compd. [11]Cl was structurally studied by single-crystal x-ray diffraction anal. The concns. corresponding to 50% inhibition of cancer cell growth (IC50 values) in the A2780 and A2780cisR cell lines of these complexes except for 6 were in the submicromolar range, complex 11 showing an IC50 value of 0.03 ?M 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 oxidn. of GSH, although there is no clear correlation between the IC50 values and the turnover frequencies at about 50% conversion. However, the cytotoxicity is tentatively correlated to the physicochem. properties of the compds. detd. by the electronic influence of the substituents X (Hammett consts. ?p) and the lipophilicity of the thiols p-XC6H4SH (calcd. log P parameters). [on SciFinder(R)]