Novel aminonaphthylcysteine (ANC) adducts, formed via naphthylnitrenium ions and/or their metabolic precursors in the biotransformation of naphthylamines (NA) and nitronaphthalenes (NN), were identified and quantified in globin of rats dosed intraperitoneally with 0.16 mmol/kg b.w. of 1-NA, 1-NN, 2-NA and 2-NN. Using HPLC-ESI-MS2 analysis of the globin hydrolysates, S-(1-amino-2-naphthyl)cysteine (1A2NC) together with S-(4-amino-1-naphthyl)cysteine (4A1NC) were found in rats given 1-NA or 1-NN, and S-(2-amino-1-naphthyl)cysteine (2A1NC) in those given 2-NA or 2-NN. The highest level of ANC was produced by the most mutagenic and carcinogenic isomer 2-NA (35.8 ± 5.4 nmol/g globin). The ratio of ANC adduct levels for 1-NA, 1-NN, 2-NA and 2-NN was 1:2:100:3, respectively. Notably, the ratio of 1A2NC:4A1NC in globin of rats dosed with 1-NA and 1-NN differed significantly (2:98 versus 16:84 respectively), indicating differences in mechanism of the adduct formation. Moreover, aminonaphthylmercapturic acids, formed via conjugation of naphthylnitrenium ions and/or their metabolic precursors with glutathione, were identified in the rat urine. Their amounts excreted after dosing rats with 1-NA, 1-NN, 2-NA and 2-NN were in the ratio 1:100:40:2, respectively. For all four compounds tested, haemoglobin binding index for ANC was several-fold higher than that for the sulphinamide adducts, generated via nitrosoarene metabolites. Due to involvement of electrophilic intermediates in their formation, ANC adducts in globin may become toxicologically more relevant biomarkers of cumulative exposure to carcinogenic or non-carcinogenic arylamines and nitroarenes than the currently used sulphinamide adducts.
- MeSH
- 1-naftylamin aplikace a dávkování metabolismus toxicita MeSH
- 2-naftylamin aplikace a dávkování metabolismus toxicita MeSH
- acetylcystein analogy a deriváty moč MeSH
- biologické markery krev moč MeSH
- cystein MeSH
- globiny metabolismus MeSH
- injekce intraperitoneální MeSH
- naftaleny aplikace a dávkování krev toxicita MeSH
- potkani Wistar MeSH
- vazba proteinů MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
3-Nitrobenzanthrone (3-NBA) is an extremely potent mutagen and suspect human carcinogen found in diesel exhaust. Its isomer 2-nitrobenzanthrone (2-NBA) has also been found in ambient air. These isomers differ in mutagenicity in Salmonella by 2-3 orders of magnitude. To identify their urinary metabolites and also to assess the assumed differences in their excretion, rats were dosed orally with 2mg/kg b.w. of either 2-NBA or 3-NBA. Their urine was collected for two consecutive days after dosage. Both LC-ESI-MS and GC-MS confirmed formation of the corresponding aminobenzanthrones (ABA). Excretion of these metabolites within the first day after dosing with 2- and 3-ABA amounted to 0.32±0.06 and 0.83±0.40% of the doses, respectively, while the excretion within the second day was by one order of magnitude lower. A novel mercapturic acid metabolite of 3-NBA was identified in urine by LC-ESI-MS as N-acetyl-S-(3-aminobenzanthron-2-yl)cysteine (3-ABA-MA) by comparison with the authentic standard. Its excretion amounted to 0.49±0.15 and 0.02±0.01% of dose within the first and second day after dosing, respectively. In contrast, no mercapturic acid was detected in the urine of rats dosed with 2-NBA. Observed difference in the mercapturic acid formation between 2- and 3-NBA is a new distinctive feature reflecting differences in the critical step of their metabolism, i.e., benzanthronylnitrenium ion formation that is intrinsically associated with biological activities of these two isomers. Moreover, 3-ABA-MA is a promising candidate biomarker of exposure to the carcinogenic 3-NBA.
- MeSH
- acetylcystein moč MeSH
- benz(a)anthraceny chemie farmakokinetika moč MeSH
- hmotnostní spektrometrie s elektrosprejovou ionizací MeSH
- karcinogeny chemie metabolismus MeSH
- krysa rodu rattus MeSH
- látky znečišťující vzduch chemie farmakokinetika moč MeSH
- magnetická rezonanční spektroskopie MeSH
- plynová chromatografie s hmotnostně spektrometrickou detekcí MeSH
- potkani Wistar MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
New metabolites of styrene, three isomeric vinylphenylmercapturic acids (2-, 3-, and 4-VPMA), were recently identified by LC-ESI-MS in the urine of mice. In this study, 4-VPMA together with traces of 2- and 3-VPMA were found also in the urine of hand-lamination workers, which were exposed to styrene vapours at concentrations ranging from 23 to 244mg/m(3). Concentrations of 4-VPMA in these end-of-shift samples were 4.59±3.64ng/mL (mean±S.D.; n=10), those found next morning after the work-shift were 2.14±2.07ng/mL (mean±S.D.; n=10). Strong correlation (R=0.959) was found in the next-morning samples between concentrations of 4-VPMA and phenylglyoxylic acid, whereas correlations found between 4-VPMA and mandelic acid in both end-of-shift and next-morning samples were much weaker. The excretion of 4-VPMA accounted for only about 3.5×10(-4)% of the absorbed dose of styrene. Despite very low metabolic yield, formation of VPMAs clearly indicates occurrence and extent of styrene ring oxidation considered to be a toxicologically relevant metabolic pathway.
- MeSH
- acetylcystein analogy a deriváty moč MeSH
- biologické markery moč MeSH
- chemický průmysl MeSH
- lidé MeSH
- oxidace-redukce MeSH
- plastické hmoty MeSH
- pracovní expozice analýza MeSH
- styren metabolismus MeSH
- vinylové sloučeniny moč MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The urine from mice exposed to styrene vapors (600 and 1200 mg/m(3), 6 h) was analyzed for ring-oxidized metabolites of styrene. To facilitate the identification of metabolites in urine, the following potential metabolites were prepared: 2-, 3-, and 4-vinylphenol (2-, 3-, and 4-VP), 4-vinylpyrocatechol, and 2-, 3-, and 4-vinylphenylmercapturic acid (2-, 3-, and 4-VPMA). For the analysis of vinylphenols beta-glucuronidase-treated urine was extracted and derivatized with acetanhydride/triethylamine before injection into GC/MS. Three isomers, 2-, 3-, and 4-VP, were found in the exposed urine using authentic standards. Additionally, three novel minor urinary metabolites, arylmercapturic acids 2-, 3-, and 4-VPMA, were identified by LC-ESI-MS(2) by comparison with authentic standards. Excretion of the most abundant isomer, 4-VPMA, amounted to 535 +/- 47 nmol/kg and 984 +/- 78 nmol/kg, representing approximately 0.047 and 0.043% of the absorbed dose for the exposure levels of 600 and 1200 mg/m(3), respectively. The ratio of 2-VPMA, 3-VPMA, and 4-VPMA was approximately 2:1:6. In model reactions of styrene 3,4-oxide (3,4-STO) with N-acetylcysteine in aqueous solutions and of its methyl ester in methanol, 4-vinylphenol was always the main product, while 3-vinylphenol has never been detected. No mercapturic acid was found in the reaction of 3,4-STO with N-acetylcysteine in aqueous solution at pH 7.4 or 9.7, but a small amount of 4-VPMA methyl ester was detected by LC-ESI-MS after the reaction of 3,4-STO with N-acetylcysteine methyl ester. In contrast, no mercapturic acid was found in the reaction of 3,4-STO with N-acetylcysteine in aqueous solution at pH 7.4 or 9.7. These findings indicate a capability of 3,4-STO to react with cellular thiol groups despite its rapid isomerization to vinylphenol in an aqueous environment. Moreover, the in vivo formation of 2- and 3-isomers of both VP and VPMA, neither of which was formed from 3,4-STO in vitro, strongly suggests that another arene oxide, styrene 2,3-oxide, might be a minor metabolic intermediate of styrene.
- MeSH
- acetylcystein analogy a deriváty moč MeSH
- fenoly moč MeSH
- hmotnostní spektrometrie s elektrosprejovou ionizací MeSH
- katecholy moč MeSH
- myši MeSH
- stereoizomerie MeSH
- styreny metabolismus MeSH
- vysokoúčinná kapalinová chromatografie MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- práce podpořená grantem MeSH
Results of a recent molecular epidemiological study of 1,3-butadiene (BD) exposed Czech workers, conducted to compare female to male responses, have confirmed and extended the findings of a previously reported males only study (HEI Research Report 116, 2003). The initial study found that urine concentrations of the metabolites 1,2-dihydroxy-4-(acetyl) butane (M1) and 1-dihydroxy-2-(N-acetylcysteinyl)-3-butene (M2) and blood concentrations of the hemoglobin adducts N-[2-hydroxy-3-butenyl] valine (HB-Val) and N-[2,3,4-trihydroxy-butyl] valine (THB-Val) constitute excellent biomarkers of exposure, both being highly correlated with BD exposure levels, and that GST genotypes modulate at least one metabolic pathway, but that irreversible genotoxic effects such as chromosome aberrations and HPRT gene mutations are neither associated with BD exposure levels nor with worker genotypes (GST [glutathione-S-transferase]-M1, GSTT1, CYP2E1 (5' promoter), CYP2E1 (intron 6), EH [epoxide hydrolase] 113, EH139, ADH [alcohol dehydrogenase]2 and ADH3). The no observed adverse effect level (NOAEL) for chromosome aberrations and HPRT mutations was 1.794 mg/m(3) (0.812 ppm)--the mean exposure level for the highest exposed worker group in this initial study. The second Czech study, reported here, initiated in 2003, included 26 female control workers, 23 female BD exposed workers, 25 male control workers and 30 male BD exposed workers (some repeats from the first study). Multiple external exposure measurements (10 full 8-h shift measures by personal monitoring per worker) over a 4-month period before biological sample collections showed that BD workplace levels were lower than in the first study. Mean 8-h TWA exposure levels were 0.008 mg/m(3) (0.0035 ppm) and 0.397 mg/m(3) (0.180 ppm) for female controls and exposed, respectively, but with individual single 8-h TWA values up to 9.793 mg/m(3) (4.45 ppm) in the exposed group. Mean male 8-h TWA exposure levels were 0.007 mg/m(3) (0.0032 ppm) and 0.808 mg/m(3) (0.370 ppm) for controls and exposed, respectively; however, the individual single 8-h TWA values up to 12.583 mg/m(3) (5.72 ppm) in the exposed group. While the urine metabolite concentrations for both M1 and M2 were elevated in exposed compared to control females, the differences were not significant, possibly due to the relatively low BD exposure levels. For males, with greater BD exposures, the concentrations of both metabolites were significantly elevated in urine from exposed compared to control workers. As in the first study, urine metabolite excretion patterns in both sexes revealed conjugation to be the minor detoxification pathway (yielding the M2 metabolite) but both M1 and M2 concentration values were lower in males in this second study compared to their concentrations in the first, reflecting the lower external exposures of males in this second study compared to the first. Of note, females showed lower concentrations of both M1 and M2 metabolites in the urine per unit of BD exposure than did males while exhibiting the same M1/(M1+M2) ratio, reflecting the same relative utilization of the hydrolytic (producing M1) and the conjugation (producing M2) detoxification pathways as males. Assays for the N,N-(2,3-dihydroxy-1,4-butadyl) valine (pyr-Val) hemoglobin (Hb) adduct, which is specific for the highly genotoxic 1,2,3,4-diepoxybutane (DEB) metabolite of BD, have been conducted on blood samples from all participants in this second Czech study. Any adduct that may have been present was below the limits of quantitation (LOQ) for this assay for all samples, indicating that production of this important BD metabolite in humans is below levels produced in both mice and rats exposed to as little as 1.0 ppm BD by inhalation (J.A. Swenberg, M.G. Bird, R.J. Lewis, Future directions in butadiene risk assessment, Chem. Biol. Int. (2006), this issue). Results of assays for the HB-Val and THB-Val hemoglobin adducts are pending. HPRT mutations, determined by cloning assays, and multiple measures of chromosome level changes (sister-chromatid exchanges [SCE], aberrations determined by conventional methods and FISH) again showed no associations with BD exposures, confirming the findings of the initial study that these irreversible genotoxic changes do not arise in humans occupationally exposed to low levels of BD. Except for lower production of both urine metabolites in females, no female-male differences in response to BD exposures were detected in this study. As in the initial study, there were no significant genotype associations with the irreversible genotoxic endpoints. However, as in the first, differences in the metabolic detoxification of BD as reflected in relative amounts of the M1 and M2 urinary metabolites were associated with genotypes, this time both GST and EH.
- MeSH
- acetylcystein analogy a deriváty moč MeSH
- benzen analýza MeSH
- butadieny aplikace a dávkování škodlivé účinky MeSH
- chemický průmysl * MeSH
- chromozomální aberace účinky léků MeSH
- dospělí MeSH
- genotyp MeSH
- hemoglobiny metabolismus MeSH
- hypoxanthinfosforibosyltransferasa genetika MeSH
- lidé MeSH
- molekulární epidemiologie MeSH
- mutace genetika MeSH
- pohlavní dimorfismus * MeSH
- pracovní expozice škodlivé účinky statistika a číselné údaje MeSH
- pracovní síly MeSH
- styren analýza MeSH
- toluen analýza MeSH
- výměna sesterských chromatid účinky léků genetika MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
- Geografické názvy
- Česká republika MeSH
- MeSH
- acetylcystein analogy a deriváty moč MeSH
- akrolein aplikace a dávkování farmakokinetika toxicita MeSH
- alveolokapilární membrána účinky léků MeSH
- biotransformace MeSH
- krysa rodu rattus MeSH
- myši MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- myši MeSH
- zvířata MeSH
- MeSH
- acetylcystein analogy a deriváty moč MeSH
- akryláty farmakokinetika metabolismus MeSH
- cystein analogy a deriváty moč MeSH
- krysa rodu rattus MeSH
- laktáty moč MeSH
- látky znečišťující vzduch v pracovním prostředí metabolismus MeSH
- magnetická rezonanční spektroskopie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- ženské pohlaví MeSH
- zvířata MeSH
Excretion of N,N-dimethylformamide (DMF) and DMF metabolites N-hydroxymethyl-N-methylformamide ("MF"), N-hydroxymethyl-formamide ("F") and N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) has been monitored in the urine of volunteers during and after their 8-h exposure to DMF vapour at a concentration of 10, 30 and 60 mg.m-3. The pulmonary ventilation in these experiments was typically about 10 l.min-1 and the retention in the respiratory tract was 90%. After exposure to 30mg DMF.m-3, the yield of compound determined in the urine represented 0.3% (DMF), 22.3% ("MF"), 13.2% ("F") and 13.4% (AMCC) of the dose absorbed via the respiratory tract. The excretion curves of the particular compounds attained their maximum 6-8h (DMF), 6-8h ("MF"), 8-14h ("F") and 24-34h (AMCC) after the start of the exposure. The half-times of excretion were approximately 2, 4, 7 and 23 h respectively. In contrast to slow elimination of AMCC after exposure to DMF, AMCC was eliminated rapidly after AMCC intake. This discrepancy could be explained by rate-limiting reversible protein binding of a reactive metabolic intermediate of DMF, possibly methylisocyanate.
- MeSH
- absorpce MeSH
- acetylcystein analogy a deriváty moč MeSH
- dimethylformamid analogy a deriváty farmakokinetika metabolismus MeSH
- dospělí MeSH
- formamidy metabolismus MeSH
- lidé středního věku MeSH
- lidé MeSH
- plíce fyziologie metabolismus MeSH
- rozpouštědla farmakokinetika metabolismus MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
Skin penetration fo N,N-dimethylformamide (DMF) liquid or vapour was studied in volunteers. Exposure to liquid DMF was performed in two ways: in a "dipping experiment", one hand was dipped up to the wrist in DMF for 2-20 min, while in a "patch experiment", 2 mmol DMF was applied to the skin and allowed to be absorbed completely. The period of exposure to DMF vapour (50 mg.m-3) was 4 h. The DMF metabolites N-hydroxymethyl-N-methylformamide ("MF"), N-hydroxymethylformamide ("F"), and N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) were monitored in the urine. Liquid DMF was absorbed through the skin at a rate of 9.4 mg.cm-2.h-1. Percutaneous absorption of DMF vapour depended strongly on ambient temperature and humidity and accounted for 13%-36% of totally excreted "MF". The results suggest that skin absorption of liquid DMF is likely to contribute to occupational exposure substantially more than penetration of DMF vapour. The yield of metabolites after transdermal DMF absorption was only half of that seen after pulmonary absorption. Elimination of "MF" and "F" but not that of AMCC was delayed, which supports the contention that AMCC should be used instead of "MF" as the most suitable biomarker of DMF in cases where percutaneous intake can occur.
- MeSH
- acetylcystein analogy a deriváty moč MeSH
- dimethylformamid analogy a deriváty farmakokinetika chemie metabolismus MeSH
- dospělí MeSH
- formamidy metabolismus MeSH
- kožní absorpce * MeSH
- lidé středního věku MeSH
- lidé MeSH
- plyny MeSH
- rozpouštědla farmakokinetika chemie metabolismus MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
