title: Noninvasive measurement of aristolochic acid-DNA adducts in urine samples from aristolochic acid-treated rats by liquid chromatography coupled tandem mass spectrometry: evidence for DNA repair by nucleotide-excision repair mechanisms.
abstract: Nephrotoxic aristolochic acids (AAs) form covalently bonded DNA adducts upon metabolic activation. In this work, a non-invasive approach to detect AAs exposure by quantifying urinary excreted DNA-AA adducts is presented. The developed method entails solid-phase extraction (SPE) enrichment of the urine-excreted DNA-AAs adducts, addition of internal standard, and quantification by liquid chromatography coupled tandem mass spectrometric (LC-MS/MS) analysis. Quantitative analysis revealed 7-(deoxyadenosine-N(6)-yl)-aristolactam II and 7-(deoxyguanosine-N(2)-yl)-aristolactam I that were previously detected as major DNA-AA adducts in different organs of AA-dosed rats, were detected as the major urine excreted adducts. Lower levels of 7-(deoxyadenosine-N(6)-yl)-aristolactam I and 7-(deoxyguanosine-N(2)-yl)-aristolactam II were also detected in the collected urine samples. The identities of the detected urinary DNA-AA adducts were confirmed by comparing chromatographic retention time with synthetic standards, by high-accuracy MS, and MS/MS analyses. LC-MS/MS analysis of the urine samples collected from the AAs-dosed rats demonstrated a time-dependent decrease in the urinary adduct levels, indicating the urinary DNA-AA adduct levels were reflective of the tissue adduct levels. It is expected that the developed approach of detecting urinary DNA-AA adducts will facilitate further carcinogenesis investigations of AAs.
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
authors.forename: Elvis M K
authors.initials: EM
authors.lastname: Leung
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China. Electronic address: chanwan@ust.hk.
authors.forename: Wan
authors.initials: W
authors.lastname: Chan
mesh_terms: D000818:Animals; D034341:Aristolochic Acids / Q000633:toxicity* / Q000652:urine*; D002273:Carcinogens / Q000032:analysis / Q000633:toxicity; D002853:Chromatography, Liquid / Q000379:methods; D018736:DNA Adducts / Q000652:urine*; D004260:DNA Repair / Q000187:drug effects; D057230:Limit of Detection; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry / Q000379:methods*; D016482:Urinalysis / Q000379:methods*
chemical_list: D034341:Aristolochic Acids; D002273:Carcinogens; D018736:DNA Adducts; C000228:aristolochic acid I
keywords: Aristolochic acids; Balkan endemic nephropathy; DNA adducts; LC–MS/MS; Nucleotide-excision repair; Urine