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  • 1
    ISSN: 1432-0738
    Keywords: Dibutylnitrosamine ; Metabolism ; Human ; Rat ; Liver ; intestine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The metabolism of the bladder carcinogen N-nitroso-di-n-butylamine (NDBA) was studied in microsomal preparations of tissues of patients of both sexes, aged 59–69 years undergoing abdominal surgery. Samples of liver, ileum, and colon were of normal histological appearance. For comparison, samples of rat liver and small intestinal mucosa microsomes were included in the study. Using 1-14C-labeled NDBA, the biotransformation to hydroxylation products retaining the nitroso group, NDBA-2-OH, NDBA-3-OH, and NDBA-4-OH, respectively, was investigated by reversed phase HPLC. In order to separate these metabolites, pooled samples were analysed by normal phase HPLC. The rate of hydroxylation of NDBA was found to be 5.5 times higher in rat liver microsomes compared to those from human liver (2.86±0.29 vs 0.52±0.03 nM x min−1 x mg−1). NDBA-3-OH proved to be the major metabolite formed (〉80% of total metabolites). The metabolism of NDBA was low but detectable in seven out of nine specimens of human gut, 0.1–0.5 nM x mg−1 in 1 h of incubation, and of the same order of magnitude in rat intestinal tissue (0.4–0.6 nM x mg−1).
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' journal of analytical chemistry 360 (1998), S. 679-682 
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract N-Nitroso-triazine herbicide species were synthesized as reference standards and their reaction products were separated by TLC. The method was established for analytical as well as for preparative amounts to achieve a sufficient separation between the educts, the byproducts and the N-nitrosated moieties. Separation of the reaction mixture was performed by two-dimensional TLC, using different mobile phases for each dimension. In the second dimension two developments were executed using the same solvent mixture. To examine the quality of performance, the separation zones were scrapped off, extracted and analyzed in the HPLC-diode array detection (DAD) mode in comparison with standards of the educts and the products of their N-nitrosation. This method minimizes the contact with the resulting N-nitroso compounds. At present nothing is known about the toxicological relevance or risk assessment on human health of N-nitrosocyanazine or N-nitrosoterbuthylazine species. Therefore the practical handling of these putative mutagenic and carcinogenic substances should be seen under the aspect of precaution and prevention of contamination.
    Type of Medium: Electronic Resource
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