Cellular and cell-free studies of catalytic DNA cleavage by ruthenium polypyridyl complexes containing redox-active intercalating ligands.

The ruthenium(ii) polypyridyl complexes (RPCs), [(phen)Ru(tatpp)] ( ) and [(phen)Ru(tatpp)Ru(phen)] ( ) are shown to cleave DNA in cell-free studies in the presence of a mild reducing agent, glutathione (GSH), in a manner that is enhanced upon lowering the [O]. Reactive oxygen species (ROS) are involved in the cleavage process as hydroxy radical scavengers attenuate the cleavage activity. Cleavage experiments in the presence of superoxide dismutase (SOD) and catalase reveal a central role for HO as the immediate precursor for hydroxy radicals.