DNA interaction, antioxidant activity, and bioactivity studies of two ruthenium(II) complexes.

Two new ruthenium(II) polypyridyl complexes Ru(dmb)2(dcdppz)2 (1) and Ru(bpy)2(dcdppz)2 (2) were prepared and characterized. The crystal structure of the complex 2 was solved by single crystal X-ray diffraction. The complex crystallizes in the monoclinic system, space group P21/n with a=12.9622(14)Å, b=17.1619(19)Å, c=22.7210(3)Å, β=100.930(2)(°), R=0.0536, Rω=0.1111. The DNA-binding constants for complexes 1 and 2 were determined to be 1.92×10(5) (s=1.72) and 2.24×10(5) (s=1.86)M(-1), respectively. The DNA-binding behaviors showed that complexes 1 and 2 interact with DNA by intercalative mode. The antioxidant activities of the ligand and the complexes were performed. Ligand, dcdppz, has no cytotoxicity against the selected cell lines. Complex 1 shows higher cytotoxicity than complex 2, but lower than cisplatin toward selected cell lines. The apoptosis and cell cycle arrest were investigated, and the apoptotic mechanism of BEL-7402 cells was studied by reactive oxygen species (ROS), mitochondrial membrane potential and western blot analysis. Complex 1 induces apoptosis in BEL-7402 cells through ROS-mediated mitochondrial dysfunction pathway and by regulating the expression of Bcl-2 family proteins.