DNA cleavage induced by alkoxyl radicals generated in the photolysis of N-alkoxypyridinethiones.
The photolysis of N-isopropoxypyridine-2-thione (1b) and of N-tert-butoxypyridine-2-thione (1c) generated alkoxyl radicals as confirmed by trapping experiments with DMPO and subsequent EPR spectroscopy. Upon UVA irradiation, the alkoxyl-radical sources induce strand breaks in supercoiled pBR 322 DNA, which was analyzed by gel electrophoresis. The participation of type I (electron transfer, H abstraction) or type II (1O2) photosensitization in the DNA cleavage by the oxyl-radical sources 1a-d or their photoproducts could be excluded. The present study establishes unequivocally that alkoxyl and benzoyloxyl, as well as hydroxyl radicals, cause strand breaks in DNA and, thus, may play a significant role in the DNA cleavage by peroxides.
Adam
W
W
Institute of Organic Chemistry, University of Würzburg, Germany.
Grimm
G N
GN
Saha-Möller
C R
CR
D000438:Alcohols / Q000737:chemistry / Q000494:pharmacology*; D004249:DNA Damage; D004278:DNA, Superhelical / Q000187:drug effects*; D004578:Electron Spin Resonance Spectroscopy; D004587:Electrophoresis, Agar Gel; D005609:Free Radicals; D017665:Hydroxyl Radical / Q000494:pharmacology; D007700:Kinetics; D010782:Photolysis; D011725:Pyridines / Q000737:chemistry*; D013871:Thiones / Q000737:chemistry*; D014466:Ultraviolet Rays
D000438:Alcohols; D004278:DNA, Superhelical; D005609:Free Radicals; C110287:N-isopropoxypyridine-2-thione; C110288:N-tert-butoxypyridine-2-thione; D011725:Pyridines; D013871:Thiones; C059688:alkoxyl radical; D017665:Hydroxyl Radical