8-Hydroxy-2'-deoxyguanosine (8-OH-dG) is a
biomarker for oxidative stress on
DNA, a common lesion in mammalian cells. A correlation between increased levels of
8-OH-dG and diseases like diabetes,
infections and
cystic fibrosis has been found in humans.
8-OH-dG levels have been shown to be decreased by
antioxidants, an indication of the importance of dietary habits.
8-OH-dG is used as a
biomarker for oxidative stress in vivo as well as in vitro and is suggested to be a mutagenic DNA lesion. Different methods are used for the analyses of
8-OH-dG, i.e. GC-MS, HPLC-EC and 32P-postlabeling. The most commonly used method is HPLC-EC. In the analysis of
8-OH-dG, the work-up procedure for
DNA, as well as the preparation for analysis, are of critical importance as there is a risk for auto-oxidation of
deoxyguanosine (dG), which would result in false high background levels and low sensitivity in analysis. 32P-Postlabeling has recently been applied to the analysis of
8-OH-dG and has shown to be a very sensitive method for the detection of
DNA adducts. It is shown here that after extrapolation to normal 32P-postlabeling conditions, [32P]
ATP generated
8-OH-dG to levels of 25 8-
OH-dG/10(5) dG. [32P]
ATP mediated the formation of
8-OH-dG from dG in a dose-dependent manner at all dose levels (0.13-12 microCi). The reaction occurred immediately and increased with time in a linear dose-response fashion. At high doses (6.0 and 12 microCi) the dose-response declined after 24 h, which indicates a possible decomposition or rearrangement of
8-OH-dG. A repeated experiment with 5 microCi [32P]
ATP during 2 h resulted in a linear formation of
8-OH-dG and a level of 19 8-
OH-dG/10(5) dG. The results indicated that awareness of the auto-oxidation generated by 32P[
ATP] in the postlabeling assay is of utmost importance and that dG must be separated before 32P-postlabeling of
8-OH-dG.