Metabolism of 2,4-dinitrotoluene by Salmonella typhimurium strains TA98, TA98NR and TA98/1,8-DNP6, and mutagenicity of the metabolites of 2,4-dinitrotoluene and related compounds to strains TA98 and TA100

Sayama, Michio; Mori, Masaaki; Nakada, Yoshikatsu; Kagamimori, Sadanobu; Kono, Hiroshi

doi:10.1016/0165-7992(91)90132-n

Cited by 7 publications

(2 citation statements)

References 22 publications

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“…leads to close to 25% yield of azoxyarenes, the condensation products of nitroso- and hydroxylamine metabolites [ 23 ]. Nitroso metabolites of dinitrotoluene were transiently formed by Salmonella typhimurium with a close to 50% yield even under anaerobic conditions [ 24 ]. In addition to reoxidation of Ar-NHOH by O 2 , a possible cause is limited NAD(P)H regeneration.…”

Section: Discussionmentioning

confidence: 99%

Mechanism of Two-/Four-Electron Reduction of Nitroaromatics by Oxygen-Insensitive Nitroreductases: The Role of a Non-Enzymatic Reduction Step

et al. 2018

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Oxygen-insensitive NAD(P)H:nitroreductases (NR) reduce nitroaromatics (Ar-NO2) into hydroxylamines (Ar-NHOH) through nitroso (Ar-NO) intermediates. Ar-NO may be reduced both enzymatically and directly by reduced nicotinamide adenine dinucleotide or its phosphate NAD(P)H, however, it is unclear which process is predominant in catalysis of NRs. We found that E. coli NR-A (NfsA) oxidizes 2 mol of NADPH per mol of 2,4,6-trinitrotoluene (TNT) and 4 mol of NADPH per mol of tetryl. Addition of ascorbate, which reduces Ar-NO into Ar-NHOH, changes the stoichiometry NADPH/Ar-NO2 into 1:1 (TNT) and 2:1 (tetryl), and decreases the rate of NADPH oxidation. Ascorbate does not interfere with the oxidation of NADPH during reduction of quinones by NfsA. Our analysis of ascorbate inhibition patterns and both enzymatic and non-enzymatic reduction of nitrosobenzene suggests that direct reduction of Ar-NO by NADPH rather than enzymatic reduction is the predominant mechanism during nitroaromatic reduction.

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Section: Discussionmentioning

confidence: 99%

Mechanism of Two-/Four-Electron Reduction of Nitroaromatics by Oxygen-Insensitive Nitroreductases: The Role of a Non-Enzymatic Reduction Step

et al. 2018

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“…Dies war um den Preis der Ver nach läs si gung des seiner zeit noch um strit te nen bzw. ge rin gen gen to xi schen Po ten zi als von 2,4DNT [16] und sei ner re duk ti ven Me ta bo li te [22] 2NT, He xyl, Te tryl, 4A2,6DNT und 2A4,6DNT. Für die ver blei ben den 5 Stoffe (2NT, He xyl, Te tryl, 4A2,6DNT und 2A4,6DNT) wa ren 1994/1996 von uns ledig lich Vor sor ge wer te auf Grund la ge einer ver mu te ten oder be grenzt be kannten Gen to xi zi tät vor ge schla gen wor den.…”

Section: 4dntunclassified

Neue Trinkwasser-Leitwerte für monocyclische Nitroverbindungen

Wollin

Dieter

2005

Bundesgesundheitsbl - Gesundheitsforsch - Gesundheitsschutz

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Nitro compounds are important industrial chemicals with a broad range of applications. During their commercial production or practical use and through leaching from military waste sites they may be released into the environment and thus lead to a contamination of drinking water resources. In the last 15-20 years, the wider public first became aware of nitro compounds as contaminants in groundwater and drinking water resources that originated from manufacturing and processing of secondary explosives during World War II. In 1980, the former Bundesgesundheitsamt (BGA; Federal Health Office) had based its first risk assessment of monocyclic nitro compounds in drinking water on the known carcinogenicity of some aromatic amines in the working environment. On this basis, the BGA recommended for metabolites of aromatic nitro compounds a guide value of 0.1 mug/l for the sum of aromatic amines. From the beginning to the middle of the 1990s, the BGA established a more specific health-related assessment for the individual compounds, but not on the basis of tolerable or acceptable body doses but of dimensionless risk assessment scores ranking their combined toxic and carcinogenic potential on a scale from 1 to 100. In this contribution, we derived new health-based drinking water guide values for 19 nitro(aromatic) compounds and nitramines, including hexogen, octogen, and tetryl as well as the O-nitro compound PETN. All compounds under consideration have been detected within the last 15 years in Germany at contaminated sites close to or directly in groundwater resources for drinking water. For toxicological evaluation and derivation of guideline values for the nitro compounds of interest, the tolerable daily intake (TDI) approach was used for chemicals exhibiting a threshold for toxic effects. This was done by using established tolerable body doses for humans based on an identified NOAEL/LOAEL for the most sensitive toxic endpoint. In the case of non-threshold chemical substances, suitable estimates of excess lifetime cancer risk have been applied.

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Combining different assays and chemical analysis to characterize the genotoxicity of waters impacted by textile discharges

Vacchi

Vendemiatti

Brosselin

et al. 2016

Environ and Mol Mutagen

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Waters receiving textile discharges can exhibit genotoxic and mutagenic activity, which has been related to the presence of dyes and aromatic amines as synthesis precursors or byproducts. The aim of this study was to identify dyes and aromatic amines in water samples impacted by textile discharges, and to evaluate the genotoxic responses of these samples using the Salmonella/microsome assay in strains TA98 and YG1041, and the Fpg-modified comet assay in the RTL-W1 fish cell line. The genotoxicity of river samples downstream of the discharge was greater than the upstream samples in both of the Ames tests. The Fpg-modified comet assay detected similar levels of DNA damage in the upstream and downstream samples. Mutagenicity was not detected with TA98, except for the Quilombo River samples, but when YG1041 was used as the tester strain mutagenicity was detected for all sites with a very different profile in upstream sites relative to the other sites. The mutagenic response strongly indicated that aromatic amines or dyes were contributing to the mutagenic activity downstream. The impact of textile discharges was also confirmed by chemical analysis, because the highest concentrations of azo dyes and aromatic amines were detected in the river downstream. This study shows the value of combining assays measuring complementary endpoints to better characterize the mutagenicity of environmental samples, with the advantage that this approach provides an indication of what classes of compounds are responsible for the effect. Environ. Mol. Mutagen. 57:559-571, 2016. © 2016 Wiley Periodicals, Inc.

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Metabolism of 2,4-dinitrotoluene by Salmonella typhimurium strains TA98, TA98NR and TA98/1,8-DNP6, and mutagenicity of the metabolites of 2,4-dinitrotoluene and related compounds to strains TA98 and TA100

Cited by 7 publications

References 22 publications

Mechanism of Two-/Four-Electron Reduction of Nitroaromatics by Oxygen-Insensitive Nitroreductases: The Role of a Non-Enzymatic Reduction Step

Mechanism of Two-/Four-Electron Reduction of Nitroaromatics by Oxygen-Insensitive Nitroreductases: The Role of a Non-Enzymatic Reduction Step

Neue Trinkwasser-Leitwerte für monocyclische Nitroverbindungen

Combining different assays and chemical analysis to characterize the genotoxicity of waters impacted by textile discharges

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