Antitumor Activity of Some Ruthenium Derivatives in Human Colon Cancer Cell Lines in Vitro

Six ruthenium derivatives were evaluated in vitro in two human colon cancer cell lines (SW707 and SW948) utilizing the microculture tetrazolium test (MTT) and cell counting with a Coulter Counter. The ruthenium compound sodium-(tetrachloroimidazoledimethylsulfoxideruthenate)- bisdimethylsulfoxide (Na(RuDMSOimCl4)) showed the best efficacy in inhibiting cell proliferation of both colon cancer cell lines followed by the other DMSO ruthenium compound sodium-(tetrachloroindazoledimethylsulfoxideruthenate) - bisdimethylsulfoxide (Na(RuDMSOIndCl4)), as demonstrated by IC50 values (80 and 90 micrograms/ml in SW707 and SW948 cell lines for Na(RuDMSOImCl4); 155 and 165 micrograms/ml in SW707 and SW948 cell lines for Na(RuDMSOIndCl4), respectively). Out of the ruthenium derivatives without DMSO, transindazolium - [tetrachlorobis(1H - indazole)ruthenate (III,N2)] (HInd[RuInd2Cl4(N2)]), was as active as its DMSO-containing congener whereas trans-imidazolium- [tetrachlorobisimidazoleruthenate)(III)], (HIm(RuIm2Cl4)) was less active, as shown by the IC50 values: (HIm (RuIm2Cl4) = 250 and 260 micrograms/ml in cell lines SW707 and SW948; HInd[RuInd2Cl4(N2)] = 110 and greater than 200 micrograms/ml in cell lines SW707 and SW948, respectively). The other ruthenium derivatives containing pyrazole and triazole as ligands (trans - pyrazolium (tetrachlorobispyrazoleruthenate) (III), PzH(RuPz2Cl4) and triazolium(tetrachlorobistriazoleruthenate) (III), TrH(RuTr2Cl4)) were active only at high concentrations that cannot be regarded as realistic in vivo, as shown by the respective IC50 values: (PzH(RuPz2Cl4) = 1056 and 750 micrograms/ml in cell lines SW707 and SW948; TrH(RuTr2Cl4) = 350 and 300 micrograms/ml in cell lines SW707 and SW948). The promising activity of ruthenium compounds with DMSO, indazole and imidazole as ligands should be evaluated in vivo for elucidating their possible role in the treatment of colorectal cancer.