Abstract
Oxidative stress is believed to increase the risk of lifestyle-related diseases, such as cancer and heart disease. To assess oxidative stress in vivo, 8-hydroxydeoxyguanosine (8-OH-dG) in DNA and urine is usually measured, as the most popular biomarker. Recently, 8-OH-Gua has also been measured, as a new oxidative stress marker in vivo. In this research, the utility of 8-hydroxyguanine (8-OH-Gua) as a radiation-induced oxidative stress marker was studied. Aqueous solutions of guanine and deoxyguanosine were irradiated with X- or γ-rays, and the levels of 8-OH-Gua and 8-OH-dG in the irradiated solutions were measured by HPLC-ECD. 8-OH-Gua and 8-OH-dG levels were increased dose-dependently by γ-ray irradiation up to 300 mGy. However, the dose-dependent increase of 8-OH-dG was suppressed at doses higher than 300 mGy. The 8-OH-dG in the aqueous solution was mostly decomposed by 10 Gy of X-ray irradiation. Furthermore, the formation of a new oxidation product was observed dose-dependently with X-ray irradiation of the dG solution. This new product eluted faster than 8-OH-dG on HPLC. On the other hand, the generation of 8-OH-Gua continuously increased up to 10 Gy of irradiation. In addition, very little decomposition of 8-OH-Gua was observed with 10 Gy of X-ray irradiation. These results suggest that 8-OH-Gua may be a useful marker of radiation-induced oxidative stress in vivo.
