Correlation between concentrations of 8-oxo-7,8-dihydro-2′-deoxyguanosine in urine, plasma and saliva measured by on-line solid-phase extraction LC-MS/MS

Background: 8-Oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) is the most frequently measured biomarker of oxidative stress. Chromatographic-based methods for 8-oxodGuo in urine are well established; however, the 8-oxodGuo measurement in plasma and saliva has been problematic. Methods: We firstly and successfully applied an on-line solid-phase extraction (SPE) LC-MS/MS following manual SPE pretreatment to quantify the 8-oxodGuo both in plasma and saliva. Urine, plasma and saliva specimens were simultaneously collected from 50 healthy adults and measured for 8-oxodGuo. Results: Mean baseline levels of 8-oxodGuo in plasma and saliva were 21.7 +/- 9.2 and 5.1 +/- 2.6 pg/ml, respectively, being far lower than that in urine (6.2 +/- 4.8 ng/ml). The 8-oxodGuo levels obtained in this study for plasma and saliva were, however, up to several hundred times lower than those reported by commercial ELISA kit in the literature. Furthermore, the 8-oxodGuo levels in plasma and saliva were significantly correlated with the 8-oxodGuo levels in urine (Spearman correlation coefficients, r = 033, P = 0.02 for plasma and r = 0.56,P = 0.0015 for saliva). 8-OxodGuo in plasma was also correlated with the 8-oxodGuo in saliva (r = 0.52, P= 0.0041). Conclusions: Significantly correlations were observed between plasma, saliva and urine, giving the possibility of using other body fluids in addition to urine for assessing whole body oxidative stress. (C) 2010 Elsevier B.V. All rights reserved.