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

Background8-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.MethodsWe 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.ResultsMean 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 = 0.33, 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).ConclusionsSignificantly 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.