Studies on Photocleavage, DNA Binding, Cytotoxicity, and Docking Studies of Ruthenium(II) Mixed Ligand Complexes

This article describes the synthesis and characterization of three new Ru(II) polypyridyl complexes including [Ru(phen)₂(dpphz)]²⁺ (1), [Ru(bpy)₂(dpphz)]²⁺ (2) and [Ru(dmb)₂(dpphz)]²⁺ (3) where dpphz = dipyrido[3,2-a:2',3'-c] phenazine-11-hydrazide, phen =1,10-phenanthroline, bpy = 2,2'-bipyridine and dmb = 4,4'-dimethyl2,2'-bipyridine. The binding behaviors of these complexes to calf thymus DNA (CT-DNA) were explored by spectroscopic titrations, viscosity measurements. Results suggest that these complexes can bind to CT-DNA through intercalation. However, their binding strength differs from each other; this may be attributed to difference in the ancillary ligand. The cytotoxicity of 1-3 was evaluated by MTT assay; results indicated that all complexes have significant dose dependent cytotoxicity with HeLa tumor cell line. All complexes exhibited efficient photocleavage of pBR322 DNA upon irradiation. The DNA binding ability of 1-3 was also studied by docking the complexes into B-DNA using docking program.