DNA targeted UVA photosensitization: Characterization of an extremely photopotent iodinated minor groove binding DNA ligand

Abstract

Previous studies have described UVA-induced DNA strand breakage at the binding sites of iodinated DNA minor groove binding bisbenzimidazoles. The DNA breakage, presumably mediated by the carbon-centred ligand radical produced by photodehalogenation, was also shown to be cytotoxic. The earlier studies included a comparison of three ligand isomers, designated ortho-, meta- and para-iodoHoechst, and the efficiency of photo-induction of strand breaks in plasmid DNA proved to be much higher for the ortho-isomer. We have now extended the comparison of the three isomers with respect to photo-induced cytotoxicity in K562 cells. Although the relationship between the extent of nuclear uptake and the c..