Syntheses of ruthenium(II)-4,4’-biimidazole complexes and their potential anti-tumor activity.

Synthesis and characterization of the Ru(II) complexes, [Ru(N-N)3][CF3SO3]2, where N-N is 4,4’-biimidazole (complex 1a) or 2,2’-dimethyl-4,4’-biimidazole (1b), and the DMSO complexes RuCl2(DMSO)2(N-N) are reported. The air-stable, water-sol. complexes were characterized by elemental anal., 1H NMR and IR spectroscopies, mass spectrometry, and soln. cond. Evidence is presented also for the existence of the diruthenium complexes Ru2Cl4(DMSO)4(N-N), but there are insufficient data for elucidation of their structure. The complexes (and cisplatin) were tested against human breast-cancer cells (MDA-MB-435S) using an in vitro MTT assay, a colorimetric detn. of cell viability: 1a and 1b exhibit the lowest IC50 values of 18 ± 5 and 36 ± 5 μmol/L, resp., with cisplatin exhibiting an IC50 value of 35 ± 5 μmol/L. Isolation of DNA from cells treated with a soln. of the Ru species showed no evidence of DNA-binding to the metal, although examn. of the cells indicated that Ru was being taken up into the cells. [on SciFinder(R)]