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.