DNA-binding, antioxidant activity, and bioactivity studies of ruthenium(II) complexes containing amino substituents

Two new Ru(II) complexes, [Ru(dmp)(2)(dadppz)](ClO4)(2) (1) and [Ru(dip)(2)(dadppz)](ClO4)(2) (2), were synthesized and characterized by elemental analysis, ES-MS, and H-1 NMR. DNA-binding behaviors were investigated by absorption titration and luminescence spectra. The DNA-binding constants were 3.1 (+/- 0.2)x10(4) and 3.0 (+/- 0.2)x10(5)M(-1) for 1 and 2. The antioxidant activity of these complexes against hydroxyl radical () was explored. The cytotoxicities in vitro towards A549, BEL-7402, MG-63, and SKBR-3 cells were studied by 3-(4,5dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. Complex 1 shows high cytotoxicity, but 2 is not cytotoxic towards the selected cell lines. Apoptosis and cell cycle distribution were studied by flow cytometry. The cellular uptake showed that complexes can enter into the cytoplasm. JC-1 was used as a fluorescence probe in detecting the mitochondrial membrane potential and results indicate that the mitochondrial membrane potential decreases.