Ruthenium(II) Polypyridyl Complexes: Synthesis and Studies of DNA Binding, Photocleavage, Cytotoxicity, Apoptosis, Cellular Uptake, and Antioxidant Activity

Two ruthenium (II) complexes [Ru(dmb)(2)(APIP)](ClO(4))(2) (APIP = 2(2-aminophenyl)imidazo[4,5-f][1,10]phenanthroline, dmb = 4,4'-dimethyl-2,2'-bipyridine; 1) and [Ru(dmb)(2)(HAPIP)](ClO(4))(2) (HAPIP = 2-(2-hydroxyl-4-aminophenyl) imidazo[4,5-f][1,10]phenanthroline; 2) were synthesized and characterized. DNA binding was investigated by electronic absorption titration, luminescence spectra, thermal denaturation, viscosity measurements, and photocleavage. The DNA binding constants for complexes 1 and 2 were 4.20 (+/- 0.14) x 10(4) and 5.45 (+/- 0.15) x 10(4) M(-1). The results suggest that these complexes partially intercalate between the base pairs. The cytotoxicity of complexes 1 and 2 was evaluated by MTT assay. Cellular uptake was observed under fluorescence microscopy; complexes 1 and 2 can enter into the cytoplasm and accumulate in the nuclei. Apoptosis and the antioxidant activity against hydroxyl radicals ((center dot)OH) were also explored.