Comparative study of kinetics on DNA double-strand break induced by photo- and gamma-irradiation: Protective effect of water-soluble flavonoids

The double-strand break of DNA induced by visible light and γ-rays was studied through a single-molecule observation using fluorescence microscopy. We evaluated the protective effects of water-soluble derivatives of flavonoids, α-glucosyl hesperidin (αG-HSP) and α-glucosyl rutin (αG-rutin) in a quantitative manner. With regard to photo-induced damage, αG-rutin was found to provide twice as much protection as αG-HSP, whereas the protective effect of αG-rutin against γ-ray irradiation was comparable with that of αG-HSP. This observation demonstrates the dependence of the antioxidant potentials of these compounds on the source of irradiation.