Synthesis, structure, DNA-binding properties, and cytotoxicity of ruthenium(II) polypyridyl complexes.

Many ruthenium(II) complexes show high antitumor activities, and the in vitro antitumor activities are usually related to DNA binding. We designed and synthesized two Ru(II) polypyridyl complexes, [Ru(dmp)2(fpp)]2+ (dmp=2,9-dimethyl-1,10-phenanthroline; fpp=2-[3,4-(difluoromethylenedioxy)phenyl]imidazo[4,5-f] [1,10]phenanthroline and [Ru(phen)(2)(fpp)]2+ (phen=1,10-phenanthroline). The DNA-binding properties of these complexes have been investigated by spectroscopic titration, DNA melting experiments, viscosity measurements, and photoactivated cleavage. The mechanism studies of photocleavage revealed that singlet oxygen (1O2) and superoxide anion radical (O2(.-)) may play an important role in the photocleavage. The cytotoxicity of complexes 1 and 2 have been evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) method; complex 2 shows slightly higher anticancer potency than 1 does against all the cell lines screened.