Prediction of •OH-Initiated and •NO3-Initiated Transformation Products of Polycyclic Aromatic Hydrocarbons by Electronic Structure Approaches
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ABSTRACT:
SUBMITTER: Chen X
PROVIDER: S-EPMC9330183 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Polycyclic aromatic hydrocarbons (PAHs) undergo transformation reactions with atmospheric photochemical oxidants, such as hydroxyl radicals (OH•), nitrogen oxides (NOx), and ozone (O3). The most common PAH-transformation products (PAH-TPs) are nitrated, oxygenated, and hydroxylated PAHs (NPAHs, OPAHs, and OHPAHs, respectively), some of which are known to pose potential human health concerns. We sampled four theoretical approaches for predicting the location of reactive sites on PAHs (i.e., the carbon where atmospheric oxidants attack), and hence the chemoselectivity of the PAHs. All computed results are based on density functional theory (B3LYP/6-31G(d) optimized structures and energies). The four approaches are (1) Clar's prediction of aromatic resonance structures, (2) thermodynamic stability of all OHPAH adduct intermediates, (3) computed atomic charges (Natural Bond order, ChelpG, and Mulliken) at each carbon on the PAH, and (4) average local ionization energy (ALIE) at atom or bond sites. To evaluate the accuracy of these approaches, the predicted PAH-TPs were compared to published laboratory observations of major NPAH, OPAH, and OHPAH products in both gas and particle phases. We found that the Clar's resonance structures were able to predict the least stable rings on the PAHs but did not offer insights in terms of which individual carbon is most reactive. The OHPAH adduct thermodynamics and the ALIE approaches were the most accurate when compared to laboratory data, showing great potential for predicting the formation of previously unstudied PAH-TPs that are likely to form in the atmosphere.
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Project description:This SuperSeries is composed of the SubSeries listed below.
2017-01-01 | GSE87691 | GEO
Project description:Polycyclic aromatic hydrocarbons degraders Raw sequence reads
| PRJNA590550 | ENA
Project description:Assessing the potential carcinogenicity of human toxins represents an ongoing challenge. Chronic rodent bioassays predict human cancer risk with limited reliability, and are expensive and time-consuming. To identify alternative prediction methods, we evaluated a transcriptomics-based human in vitro model to classify carcinogens by their modes of action. The aim of this study was to determine the transcriptomic response and identify specific molecular signatures of polycyclic aromatic hydrocarbons (PAHs), which can be used as predictors of carcinogenicity of environmental toxins in human in vitro systems. We found that characteristic molecular signatures facilitate identification and prediction of carcinogens.
2012-04-18 | GSE37326 | GEO
Project description:BackgroundDebate about the health implications of using smokeless tobacco products (STPs) has prompted considerable interest in characterising their levels of toxic and carcinogenic components. In the present study seventy smokeless tobacco products from the US and Sweden, categorized as chewing tobacco, dry and moist snuff, hard and soft pellets, plug, and loose and portion snus, were analysed for twenty one polycyclic aromatic hydrocarbons (PAHs). The tested brands represented 80-90% of the 2008 market share for the major STP categories in these two countries.ResultsThere were significant differences in the total and individual PAH concentrations in the different styles of product. Substantially higher levels of total PAHs (10-60 fold) were found in moist and dry snuff and soft pellets than in the other smokeless tobacco styles. The individual PAH concentrations followed the same patterns as total PAHs except for naphthalene, for which the highest concentrations were found in snus and moist snuff. Good correlations were obtained between benzo[a]pyrene (B[a]P) and all the other PAHs except naphthalene, 1-methylnaphthalene and 2-methylnaphthalene, providing evidence for the first time that it can be used as a good marker for PAHs in STPs. Results were generally in good agreement with two previous studies of PAHs in STPs, except for naphthalene for which significantly lower concentrations were found than previously reported. Analysis of the ratios of different PAHs confirmed that the use of fire-cured tobaccos in the snuffs and soft pellet were the major source of PAHs in these product styles, and provided, for the first time, some indications as to the source of PAHs in the other STP styles, including petrogenic and other combustion sources.ConclusionsThis study confirms the presence of PAHs in STPs, and identifies substantial differences between the levels in different STP categories. Since previous studies of naphthalene concentrations in STPs differed so markedly from those found in this study, it is recommended that further work on PAH determination is undertaken to investigate the source of this discrepancy.
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Project description:Polycyclic aromatic hydrocarbons-Polluted Soil Metagenome
| PRJNA656884 | ENA
Project description:Assessing the potential carcinogenicity of human toxins represents an ongoing challenge. Chronic rodent bioassays predict human cancer risk with limited reliability, and are expensive and time-consuming. To identify alternative prediction methods, we evaluated a transcriptomics-based human in vitro model to classify carcinogens by their modes of action. The aim of this study was to determine the transcriptomic response and identify specific molecular signatures of polycyclic aromatic hydrocarbons (PAHs), which can be used as predictors of carcinogenicity of environmental toxins in human in vitro systems. We found that characteristic molecular signatures facilitate identification and prediction of carcinogens. To evaluate the change in gene expression levels, human hepatocellular carcinoma (HepG2) cells were exposed to nine different PAHs (benzo[a]pyrene, dibenzo[a,h]anthracene, 3-methylcholanthrene, naphthalene, chrysene, phenanthrene, benzo[a]anthracene, benzo[k]fluoranthene, and indeno[1,2,3-c,d]pyrene) for 48 h. Gene expression analysis was conducted using a 44K whole human genome microarray (Agilent Technologies, USA).
2012-04-17 | E-GEOD-37326 | biostudies-arrayexpress
Project description:Syntheses of large polycyclic aromatic hydrocarbons (PAHs) and graphene nanostructures demand methods that are capable of selectively and efficiently fusing large numbers of aromatic rings, yet such methods remain scarce. Herein, we report a new approach that is based on the quantitative intramolecular reductive cyclization of an oligo(diyne) with a low-valent zirconocene reagent, which gives a PAH with one or more annulated zirconacyclopentadienes (ZrPAHs). The efficiency of this process is demonstrated by a high-yielding fivefold intramolecular coupling to form a helical ZrPAH with 16 fused rings (from a precursor with no fused rings). Several other PAH topologies are also reported. Protodemetalation of the ZrPAHs allowed full characterization (including by X-ray crystallography) of PAHs containing one or more appended dienes with the ortho-quinodimethane (o-QDM) structure, which are usually too reactive for isolation and are potentially valuable for the fusion of additional rings by Diels-Alder reactions.
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Project description:Polycyclic aromatic hydrocarbons (PAHs) are a class of hundreds of structurally similar chemicals ubiquitously present in our environment. They are created during the incomplete combustion of organic materials, such as oil, wood, tobacco, and charbroiled meat. As such, human exposure to mixtures of PAHs can occur through consumption of PAH-containing foods and water, inhalation of polluted air, or dermal contact. Several PAHs have been classified as carcinogenic to humans or probably carcinogenic to humans by the International Agency for Research on Cancer. The mice in this study were exposed to a mixture of 8 PAHs, benzo(a)pyrene, benz(a)anthracene, benzo(b)fluoranthene, benzo(ghi)perylene, benzo(k)fluoranthene, chrysene, dibenz(ah)anthracene, and indeno(123,cd)pyrene. In the present study, we sought to determine the dose-dependent changes in gene expression upon oral exposure to this PAH mixture in the lung tissue. Adult male MutaTMMouse were exposed to three doses of the mixture of 8 PAHs or vehicle control (olive oil) for 28 days and sacrificed three days after the final exposure.
2017-01-01 | GSE87689 | GEO
Project description:The synthesis of O-doped benzorylenes, in which peripheral carbon atoms have been replaced by oxygen atoms, has been achieved for the first time. This includes key high-yielding ring-closure steps which, through intramolecular C-O bond formation, allow stepwise planarization of oligonaphthalenes. Single-crystal X-ray diffraction showed that the tetraoxa derivative forms remarkable face-to-face ?-? stacks in the solid state, a favorable solid-state arrangement for organic electronics.
| S-EPMC5071652 | biostudies-literature