TY - JOUR
T1 - Singlet oxygen involvement in ultraviolet (254 nm) radiation-induced formation of 8-hydroxy-deoxyguanosine in DNA
AU - Wei, Huachen
AU - Cai, Qiuyin
AU - Rahn, Ronald
AU - Zhang, Xueshu
N1 - Funding Information:
This research was supported by NIH Grants (R01 CA60994 and R01 CA61764) and partially supported by grants from Alzheimer's Association (FSA-94-024) and Dermatology Foundation awarded to H. Wei.
PY - 1997
Y1 - 1997
N2 - In the present article, we report that ultraviolet (UV 254 nm) radiation substantially induced the formation of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in purified DNA. The formation of 8-OHdG, a hallmarker of oxidative DNA damage, increased linearly up to 25 kJ/m2 and was dependent on the presence of oxygen in the solution. Deoxygenation by nitrogen significantly reduced the yield of 8-OHdG by UV radiation, whereas oxygenation with 100% oxygen substantially enhanced the yield. The hydroxyl radical (HO·) scavenger dimethysulfoxide (DMSO) dramatically quenched the formation of 8-OHdG by the ionizing radiation and Fenton reaction, but enhanced the formation of UV- induced 8-OHdG. Further studies showed that DMSO and mannitol, two predominant HO· scavengers, enhanced the levels of UV-induced 8-OHdG in a dose-dependent fashion, suggesting that UV-induced 8-OHdG is independent of the generation of HO·. The use of deuterium oxide (D2O), which prolongs the half life of singlet oxygen (1O2), substantially enhanced the yield of 8- OHdG by UV radiation, but not that by Fenton reaction. In contrast, sodium azide, a more and less specific 1O2 quencher, substantially reduced the levels of 8-OHdG by both UV radiation and Fenton reaction, indicating that sodium azide lacks the quenching specificity for 1O2 and HO·. It is proposed that UV induced 8-OHdG proceeds through a singlet oxygen involvement mechanism, rather than the generation of hydroxyl radicals.
AB - In the present article, we report that ultraviolet (UV 254 nm) radiation substantially induced the formation of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in purified DNA. The formation of 8-OHdG, a hallmarker of oxidative DNA damage, increased linearly up to 25 kJ/m2 and was dependent on the presence of oxygen in the solution. Deoxygenation by nitrogen significantly reduced the yield of 8-OHdG by UV radiation, whereas oxygenation with 100% oxygen substantially enhanced the yield. The hydroxyl radical (HO·) scavenger dimethysulfoxide (DMSO) dramatically quenched the formation of 8-OHdG by the ionizing radiation and Fenton reaction, but enhanced the formation of UV- induced 8-OHdG. Further studies showed that DMSO and mannitol, two predominant HO· scavengers, enhanced the levels of UV-induced 8-OHdG in a dose-dependent fashion, suggesting that UV-induced 8-OHdG is independent of the generation of HO·. The use of deuterium oxide (D2O), which prolongs the half life of singlet oxygen (1O2), substantially enhanced the yield of 8- OHdG by UV radiation, but not that by Fenton reaction. In contrast, sodium azide, a more and less specific 1O2 quencher, substantially reduced the levels of 8-OHdG by both UV radiation and Fenton reaction, indicating that sodium azide lacks the quenching specificity for 1O2 and HO·. It is proposed that UV induced 8-OHdG proceeds through a singlet oxygen involvement mechanism, rather than the generation of hydroxyl radicals.
KW - 8-Hydroxy-2'-deoxyguanosine
KW - Fenton Reaction
KW - Ionizing radiation
KW - Oxidative DNA damage
KW - Reactive oxygen species
KW - Singlet oxygen
KW - UV radiation
UR - http://www.scopus.com/inward/record.url?scp=17544404466&partnerID=8YFLogxK
U2 - 10.1016/S0891-5849(96)00526-6
DO - 10.1016/S0891-5849(96)00526-6
M3 - Article
C2 - 9165307
AN - SCOPUS:17544404466
SN - 0891-5849
VL - 23
SP - 148
EP - 154
JO - Free Radical Biology and Medicine
JF - Free Radical Biology and Medicine
IS - 1
ER -