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