Urinary excretion of 5‐(hydroxymethyl)uracil in healthy volunteers: Effect of active and passive tobacco smoke

Publisher Website
Google Scholar
Abstract
The urinary excretion of 5-(hydroxymethyl)uracil (5-HMUra), one of the major oxidative modifications of thymine, was investigated in 134 healthy volunteers living in North Italy. Overnight urine was collected, and a questionnaire was completed on smoking habits and exposure to environmental tobacco smoke (ETS). 5-HMUra was analyzed by GC/MS, following urine purification by HPLC. 5-HMUra excretion showed an approximately normal distribution, ranging from 0.08 to 0.84 (mean 0.44) nmoles/kg/8 hr and from 3.2 to 18.7 (mean 8.5) nmoles/mmoles creatinine. 5-HMUra excretion was significantly higher in women than in men and in smokers than in non-smokers when results were expressed as the ratio to creatinine. Slightly higher levels of 5-HMUra excretion, expressed as nmoles/mmoles creatinine, were also found in subjects highly exposed to ETS, monitored either as the number of hours of exposure or as the number of smokers in the workplace and at home. Our results show that the urinary excretion of 5-HMUra is higher than that of other oxidized nucleobases, including 8-oxo-7,8-dihydroguanine, and can be slightly modified by environmental factors such as tobacco smoke. These findings suggest that measurement of urinary excretion of 5-HMUra could be useful as a biomarker of oxidative DNA damage and repair, though further research is needed to support these data.