W. Adam et al., Oxidative DNA damage in the photolysis of N-hydroxy-2-pyridone, a specifichydroxyl-radical source, PHOTOCHEM P, 70(3), 1999, pp. 287-291
The photooxidative DNA damage by N-hydroxy-2-pyridone (1) is caused by hydr
oxyl radicals, as confirmed by electron paramagnetic resonance studies with
the spin trap 5,5-dimethylpyrroline N-oxide. Irradiation of the pyridone 1
at 300 nm induced strand breaks in supercoiled pBR322 DNA, while in calf-t
hymus DNA and 2'-deoxyguanosine (dG), respectively, 8-oxoguanine and 8-oxo-
7,8-dihydro-2'-deoxyguanosine were formed. Time-dependent control experimen
ts disclosed that photoproducts of pyridone 1, e.g. 2-pyridone (3), are not
responsible for the modification of DNA, Also the photosensitization by th
e pyridine-2-one chromophore was excluded, because N-methylpyridine-2-one (
2), which cannot generate hydroxyl radicals, was ineffective in the photoox
idation of DNA and dG, Thus, the photolysis of pyridone 1 serves as a speci
fic source of hydroxyl radicals for DNA damage, both strand breaks and base
modifications.