Photoinduced DNA Cleavage and Photocytotoxic of Phenanthroline-Based Ligand Ruthenium Compounds.

The photophysical and biological properties of two new phenanthroline-based ligand ruthenium complexes were investigated in detail. Their DNA interaction modes were determined to be the intercalation mode using spectra titration and viscosity measurements. Under irradiation, obvious photo-reduced DNA cleavages were observed in the two complexes via singlet oxygen generation. Furthermore, complex 2 showed higher DNA affinity, photocleavage activity, and singlet oxygen quantum yields than complex 1. The two complexes showed no toxicity towards tumor cells (HeLa, A549, and A375) in the dark. However, obvious photocytotoxicities were observed in the two complexes. Complex 2 exhibited large PIs (phototherapeutic indices) (ca. 400) towards HeLa cells. The study suggests that these complexes may act as DNA intercalators, DNA photocleavers, and photocytotoxic agents.

Anticancer activity, topoisomerase I inhibition, DNA 'light switch' behavior and molecular docking of two ruthenium complexes containing phenazine ring.

Ruthenium(II) complexes containing phenazine ring have attracted attention to design as 'molecular light switches'. In this study, we synthesized two ruthenium complexes containing phenazine ring and studied their abilities to function as DNA intercalators, DNA 'light switches', DNA topo I inhibitors, DNA photocleavers and potential antitumor reagents. [Ru(bpy)2(mbipz)](PF6)2 (1) (bpy = 2,2'-bipyridine, mbipz = 2-(4'-methyl-bipyridine-4-yl)-1H-imidazo[4,5-b]phenazine) exhibited off-on type DNA 'light swtich' behavior. DNA binding modes of the two complexes were determined as intercalation by using UV-vis spectra, emission spectra, viscosity and molecular docking experiments. DNA photocleavage experimental results showed that the two ruthenium complexes effectively cleave plasmid DNA by producing singlet oxygen. Furthermore, they displayed good topo I inhibition activities. We further found that the two complexes displayed good antitumor activities against Eca-109 cells and A549 cells. The results demonstrated that introduction of phenazine ring will be helpful to design DNA 'light switch' based on ruthenium complex.Communicated by Ramaswamy H. Sarma.

Nitro-Substituted Ruthenium(II) Complex: A New Strategy for a G-Quadruplex DNA Fluorescent Probe.

A new strategy for a G-quadruplex fluorescent probe based on a nitro-substituted ruthenium complex is described. G-quadruplex DNA can be distinguished from double- or single-strand DNA by the naked eye. This ability originates from variation of the degree of protection of the nitro group on the complex from water by G-quadruplex and other structure DNAs.