TY - JOUR
T1 - Microbial toxicity and characterization of DNAN (bio)transformation product mixtures
AU - Olivares, Christopher I.
AU - Sierra-Alvarez, Reyes
AU - Alvarez-Nieto, Cristina
AU - Abrell, Leif
AU - Chorover, Jon
AU - Field, Jim A.
N1 - Funding Information:
This study was supported by the Strategic Environmental Research and Development Program (SERDP) project ER-2221 and NSF CBET 1510698 . Analyses performed at the Arizona Laboratory for Emerging Contaminants (ALEC) were supported by NSF CBET 0722579 , AB Sciex, and additional funding from University of Arizona colleges. CIO was supported by the Mexican National Council for Science and Technology (CONACyT) and the NIEHS Superfund Research Program ( P42 ES04940 ).
Publisher Copyright:
© 2016 Elsevier Ltd.
PY - 2016/7/1
Y1 - 2016/7/1
N2 - 2,4-Dinitroanisole (DNAN) is an emerging insensitive munitions compound. It undergoes rapid (bio)transformation in soils and anaerobic sludge. The primary transformation pathway catalyzed by a combination of biotic and abiotic factors is nitrogroup reduction followed by coupling of reactive intermediates to form azo-dimers. Additional pathways include N-acetylation and O-demethoxylation. Toxicity due to (bio)transformation products of DNAN has received little attention. In this study, the toxicity of DNAN (bio)transformation monomer products and azo-dimer and trimer surrogates to acetoclastic methanogens and the marine bioluminescent bacterium, Allivibrio fischeri, were evaluated. Methanogens were severely inhibited by 3-nitro-4-methoxyaniline (MENA), with a 50%-inhibiting concentration (IC50) of 25 μM, which is more toxic than DNAN with the same assay, but posed a lower toxicity to Allivibrio fischeri (IC50 = 219 μM). On the other hand, N-(5-amino-2-methoxyphenyl) acetamide (Ac-DAAN) was the least inhibitory test-compound for both microbial targets. Azo-dimer and trimer surrogates were very highly toxic to both microbial systems, with a toxicity similar or stronger than that of DNAN. A semi-quantitative LC-QTOF-MS method was employed to determine product mixture profiles at different stages of biotransformation, and compared with the microbial toxicity of the product-mixtures formed. Methanogenic toxicity increased due to putative reactive nitroso-intermediates as DNAN was reduced. However, the inhibition later attenuated as dimers became the predominant products in the mixtures. In contrast, A. fischeri tolerated the initial biotransformation products but were highly inhibited by the predominant azo-dimer products formed at longer incubation times, suggesting these ultimate products are more toxic than DNAN.
AB - 2,4-Dinitroanisole (DNAN) is an emerging insensitive munitions compound. It undergoes rapid (bio)transformation in soils and anaerobic sludge. The primary transformation pathway catalyzed by a combination of biotic and abiotic factors is nitrogroup reduction followed by coupling of reactive intermediates to form azo-dimers. Additional pathways include N-acetylation and O-demethoxylation. Toxicity due to (bio)transformation products of DNAN has received little attention. In this study, the toxicity of DNAN (bio)transformation monomer products and azo-dimer and trimer surrogates to acetoclastic methanogens and the marine bioluminescent bacterium, Allivibrio fischeri, were evaluated. Methanogens were severely inhibited by 3-nitro-4-methoxyaniline (MENA), with a 50%-inhibiting concentration (IC50) of 25 μM, which is more toxic than DNAN with the same assay, but posed a lower toxicity to Allivibrio fischeri (IC50 = 219 μM). On the other hand, N-(5-amino-2-methoxyphenyl) acetamide (Ac-DAAN) was the least inhibitory test-compound for both microbial targets. Azo-dimer and trimer surrogates were very highly toxic to both microbial systems, with a toxicity similar or stronger than that of DNAN. A semi-quantitative LC-QTOF-MS method was employed to determine product mixture profiles at different stages of biotransformation, and compared with the microbial toxicity of the product-mixtures formed. Methanogenic toxicity increased due to putative reactive nitroso-intermediates as DNAN was reduced. However, the inhibition later attenuated as dimers became the predominant products in the mixtures. In contrast, A. fischeri tolerated the initial biotransformation products but were highly inhibited by the predominant azo-dimer products formed at longer incubation times, suggesting these ultimate products are more toxic than DNAN.
KW - 2,4-Dinitroanisole
KW - Biotransformation
KW - Dimers
KW - Liquid chromatography quadrupole time-of-flight mass spectrometry
KW - Microbial toxicity
KW - Munitions
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U2 - 10.1016/j.chemosphere.2016.04.007
DO - 10.1016/j.chemosphere.2016.04.007
M3 - Article
C2 - 27085064
AN - SCOPUS:84962861404
VL - 154
SP - 499
EP - 506
JO - Chemosphere
JF - Chemosphere
SN - 0045-6535
ER -