Journal of Photoscience
- 제9권2호
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- Pages.488-490
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- 2002
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- 1225-8555(pISSN)
Photodamage to Double-stranded DNA by Xanthone Analogues Increases Exponentially with Their HOMO Energies
- Hirakawa, Kazutaka (Radioisotope Center, Mie University School of Medicine) ;
- Yoshida, Mami (Radioisotope Center, Mie University School of Medicine) ;
- Oikawa, Shinji (Department of Environmental and Molecular Medicine, Mie University School of Medicine) ;
- Kawanishi, Shosuke (Department of Environmental and Molecular Medicine, Mie University School of Medicine)
- 발행 : 2002.08.01
초록
DNA photodamage mediated by photosensitizers are believed to play an important role in solar UVA carcinogenesis. We investigated the relationship between the DNA-damaging abilities of photoexcited xanthone analogues (as photosensitizers) and their highest occupied molecular orbital (HOMO) energies. DNA damage was examined using /sup 32/P-labeled DNA fragments obtained from the p53 tumor suppressor gene. These compounds induced DNA photodamage in a similar manner, and the extents of DNA damage were following order: xanthone> thioxanthone > acridone. Photoexcited xanthone caused nucleobase oxidation specifically at 5'-G of GG sequence in double-stranded DNA. An oxidative product of 2'-deoxyguanosine, 8-hydroxy-2'-deoxyguanosine (8-OHdG), was detected, and the amount was decreased by DNA denaturation. These findings suggest that photoexcited xanthone generates 8-OHdG at 5'-G of GG in double-stranded DNA through electron transfer. The calculated HOMO energies of these photosensitizers decreased in the following order: xanthone> thioxanthone > acridone. This study has demonstrated that DNA-damaging abilities of these photosensitizers increased exponentially with an increase in their HOMO energies.