Oxidative damage in human DNA and urine analyzed by HPLC- electrochemical detection (HPLC-EC) and gas chromatography-mass spectrometry (GC/MS)

Reactive oxygen species (ROS) may lead to the oxidative DNA damage representing an early step in chemical carcinogenesis and the progression of tumors. The oxidative stress has been suggested as a possible mechanism of non-genotoxic chemical carcinogenesis. The oxidation to DNA may include modified bases, strand breaks and AP-sites. We have studied oxidative DNA damage using 7,8-dihydro-8-oxodeoxyguanosine (8-oxodG) and thymine glycol (TG) as biomarkers for occupational exposure to diesel exhaust. DNA was extracted from lymphocyte of 19 exposed bus garage and waste collection workers, and 18 controls. The measurement of 8-oxodG was carried out by HPLC coupled with an EC detector. High individual variations of 8-oxodG levels were observed, however, the mean 8-oxodG obtained from the exposed workers (4.8/10E5 dG) was not statistically different from the control persons (4.1/10E5 dG). Thymine glycol (TG) in urine of exposed and control persons was analyzed with TG-d4 as an internal standard. Five ml of urine was treated with the affinity column and C18 cartridges, then HPLC separations were processed. The fractions containing endogenous TG and the deuterated internal standard were derivatized with BSTFA and acetonitrile (4/1). The GC/MS analysis was performed with JMS-700 GC/MS of JEOL by the high resolution SIM mode. The TG levels in human urine were low and the purification procedure of urine samples needs to be further developed. Supported by Academy of Finland