Nucleic Acid Binding Behavior and Cytotoxicity Properties of a Ruthenium(II) Polypyridyl Complex

The binding of [Ru(IP)2(dppz-11-CO2Me)]2+ (1) {IP = imidazo[4,5-f][1,10]phenanthroline, dppz-11-CO2Me = dipyrido[3,2-a:2′,3′-c]phenazine-11-carboxylic acid methyl ester} to calf thymus DNA and yeast tRNA has been investigated by UV–Vis spectroscopy, fluorescence spectroscopy, viscosity, as well as equilibrium dialysis and circular dichroism. In addition, the antitumor activities of complex 1 have been evaluated by the MTT method. On the basis of the spectroscopic results, the binding mode of complex 1 to CT-DNA and yeast tRNA is intercalation. However, DNA binding with complex 1 is stronger than RNA binding with complex 1, and complex 1 is a better candidate for an enantioselective binder to CT-DNA than to yeast tRNA. These results indicate that the structures of DNA and RNA have significant effects on the binding behaviors of complex 1. Furthermore, complex 1 demonstrates different antitumor activities against selected cancer cell lines in vitro.