title: Measurement of urinary excretion of 5-hydroxymethyluracil in human by GC/NICI/MS: correlation with cigarette smoking, urinary TBARS and etheno DNA adduct.
abstract: 5-Hydroxymethyluracil (5-HMU) is derived from radiation in addition to endogenous oxidative DNA damage and it is one of the most abundant DNA adducts. Human 5-HMU-DNA-glycosylase has been shown to repair this lesion. Whether urinary levels of 5-HMU is a valid biomarker for oxidative DNA damage in vivo has been investigated. However, controversial results on its relation to cigarette smoking were reported. To facilitate analysis of urinary 5-HMU in epidemiological studies, a highly sensitive and specific assay based on stable isotope dilution gas chromatography/negative ion chemical ionization/mass spectrometry was developed. The limit of detection for N1,N3-bis(pentafluorobenzyl)-HMU is 10 fg (20 amol) (S/N=4) injected on column and the limit of quantification in urine was 0.7 nM of 5-HMU. Using as little as 10 microL of human urine samples, levels of urinary 5-HMU in 21 healthy volunteers were accurately quantified. No correlation was observed between urinary 5-HMU levels and cigarette smoking. However, there was a statistically significant association between urinary levels of 5-HMU and thiobarbituric acid-reactive substances (r=0.71, p=0.0003). In addition, urinary 5-HMU levels also correlated with urinary levels of 1,N6-ethenoadenine (r=0.54, p=0.01). These findings suggest that this assay should be valuable in assessing the role of urinary 5-HMU as a biomarker of oxidative DNA damage and repair.
authors.affiliation: Department of Chemistry and Biochemistry, National Chung Cheng University, 160 San-Hsing, Ming-Hsiung, Chia-Yi 62142, Taiwan. chehjc@ccunix.ccu.edu.tw
authors.forename: Hauh-Jyun Candy
authors.initials: HJ
authors.lastname: Chen
authors.forename: Chan-Fu
authors.initials: CF
authors.lastname: Wu
authors.forename: Ju-Li
authors.initials: JL
authors.lastname: Huang
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives* / Q000652:urine; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000652:urine; D018736:DNA Adducts / Q000652:urine*; D004249:DNA Damage; D005260:Female; D005464:Fluorobenzenes; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D015227:Lipid Peroxidation; D008297:Male; D008875:Middle Aged; D010432:Pentoxyl / Q000031:analogs & derivatives* / Q000652:urine*; D012907:Smoking / Q000652:urine*; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis / Q000378:metabolism; D005466:Fluorocarbons
chemical_list: D000225:Adenine; D015415:Biomarkers; D018736:DNA Adducts; D005464:Fluorobenzenes; D010432:Pentoxyl; D017392:Thiobarbituric Acid Reactive Substances; C004981:1,N(6)-ethenoadenine; C025063:pentafluorobenzyl bromide; D005466:Fluorocarbons; C008055:5-hydroxymethyluracil