Evaluation of DNA-binding and DNA-photocleavage ability of tetra-cationic porphyrins containing peripheral [Ru(bpy)2Cl]+ complexes: Insights for photodynamic therapy agents.

The present work reports the spectroscopic and theoretical evaluation of the interaction between calf-thymus DNA (CT-DNA) and free-base meso-tetra-(ruthenated) porphyrin (H2RuTPyP) or its corresponding Zn(II) complex (ZnRuTPyP). Spectroscopic measurements (UV-vis, circular dichroism and steady-state fluorescence emission) combined with theoretical molecular docking calculations suggest that Ru(II)-porphyrins interact with the DNA backbone by external mode via electrostatic forces. In addition, gel electrophoresis analysis demonstrate that these porphyrins promote efficient plasmidial DNA photocleavage upon white-light irradiation conditions, indicating H2RuTPyP and ZnRuTPyP as potential candidates for photodynamic therapy.