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Sample records for activated aromatic dinitro

  1. N-Butyl-2,4-dinitro-anilinium p-toluenesulfonate as a highly active and selective esterification catalyst

    PubMed Central

    Sattenapally, Narsimha; Wang, Wei; Liu, Huimin; Gao, Yong

    2013-01-01

    N-Butyl-2,4-dinitro-anilinium p-toluenesulfonate (1) was found to be a very active esterification catalyst that promotes condensation of equal mole amount of carboxylic acids and alcohols under mild conditions. This catalyst is also highly selective towards carboxylic acid and alcohol substrates at ambient temperature. PMID:24357885

  2. N-Butyl-2,4-dinitro-anilinium p-toluenesulfonate as a highly active and selective esterification catalyst.

    PubMed

    Sattenapally, Narsimha; Wang, Wei; Liu, Huimin; Gao, Yong

    2013-11-27

    N-Butyl-2,4-dinitro-anilinium p-toluenesulfonate (1) was found to be a very active esterification catalyst that promotes condensation of equal mole amount of carboxylic acids and alcohols under mild conditions. This catalyst is also highly selective towards carboxylic acid and alcohol substrates at ambient temperature.

  3. Polybenzimidazole via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor); Smith, Joseph G. (Inventor)

    1994-01-01

    Di(hydroxyphenyl)benzimidazole monomers were prepared from phenyl-4-hydroxybenzoate and aromatic bis(o-diamine)s. These monomers were used in the synthesis of soluble polybenzimidazoles. The reaction involved the aromatic nucleophilic displacement of various di(hydroxyphenyl)benzimidazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds in the presence of an alkali metal base. These polymers exhibited lower glass transition temperatures, improved solubility, and better compression moldability over their commercial counterparts.

  4. Polyimidazoles via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor)

    1991-01-01

    Polyimidazoles (Pl) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl)imidazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The reactions are carried out in polar aprotic solvents such as N,N-dimethylacetamide, sulfolane, N-methylpyrroldinone, dimethylsulfoxide, or diphenylsulfone using alkali metal bases such as potassium carbonate at elevated temperature under nitrogen. The di(hydroxyphenyl)imidazole monomers are prepared by reacting an aromatic aldehyde with a dimethoxybenzil or by reacting an aromatic dialdehyde with a methoxybenzil in the presence of ammonium acetate. The di(methoxyphenyl)imidazole is subsequently treated with aqueous hydrobromic acid to give the di(hydroxyphenyl)imidazole monomer. This synthetic route has provided high molecular weight Pl of new chemical structure, is economically and synthetically more favorable than other routes, and allows for facile chemical structure variation due to the availability of a large variety of activated aromatic dihalides and dinitro compounds.

  5. Polyimidazoles via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor)

    1992-01-01

    Polyimidazoles (PI) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl) imidazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The reactions are carried out in polar aprotic solvents such as N,N-dimethyl acetamide, sulfolane, N-methylpyrrolidinone, dimethylsulfoxide, or diphenylsulfone using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. The di(hydroxyphenyl) imidazole monomers are prepared by reacting an aromatic aldehyde with a dimethoxybenzil or by reacting an aromatic dialdehyde with a methoxybenzil in the presence of ammonium acetate. The di(methoxyphenyl) imidazole is subsequently treated with aqueous hydrobromic acid to give the di(hydroxphenyl) imidazole monomer. This synthetic route has provided high molecular weight PI of new chemical structure, is economically and synthetically more favorable than other routes, and allows for facile chemical structure variation due to the availability of a large variety of activated aromatic dihalides and dinitro compounds.

  6. Polybenzimidazoles via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor); Smith, Joseph G., Jr. (Inventor)

    1995-01-01

    Novel molecular weight controlled and endcapped polybenzimidazoles (PBI) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl benzimidazole) monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The PBI are endcapped with mono(hydroxyphenyl) benzimidazoles. The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N,N-dimethylacetamide using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. Mono(hydroxyphenyl) benzimidazoles are synthesizedby reacting phenyl-4-hydroxybenzoate with aromatic (o-diamine)s in diphenylsulfone. Molecular weight controlled and endcapped PBI of new chemical structures are prepared that exhibit a favorable combination of physical and mechanical properties.

  7. Polybenzimidazoles Via Aromatic Nucleophilic Displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergerrother, Paul M. (Inventor); Smith, Joseph G., Jr. (Inventor)

    1997-01-01

    Novel molecular weight controlled and endcapped polybenzimidazoles (PBI) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenylbenzimidazole) monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The PBI are endcapped with mono(hydroxyphenyl)benzimidazoles. The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N,N-dimethylacetamide using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. Mono(hydroxyphenyl)benzimidazoles are synthesized by reacting phenyl-4-hydroxybenzoate with aromatic (o-diamine)s in diphenylsulfone. Molecular weight controlled and endcapped PBI of new chemical structures are prepared that exhibit a favorable combination of physical and mechanical properties.

  8. Poly(1,3,4-oxadiazoles) via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor); Wolf, Peter (Inventor)

    1992-01-01

    Poly(1,3,4-oxadiazoles) (POX) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl) 1,3,4-oxadiazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The polymerizations are carried out in polar aprotic solvents such as sulfolane or diphenylsulfone using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. The di(hydroxyphenyl) 1,3,4-oxadiazole monomers are synthesized by reacting 4-hydroxybenzoic hydrazide with phenyl 4-hydrobenzoate in the melt and also by reacting aromatic dihydrazides with two moles of phenyl 4-hydroxybenzoate in the melt. This synthetic route has provided high molecular weight POX of new chemical structure, is economically and synthetically more favorable than other routes, and allows for facile chemical structure variation due to the large variety of activated aromatic dihalides which are available.

  9. Evaluation of antibacterial activity of synthetic aliphatic and aromatic monoacylglycerols.

    PubMed

    Batovska, Daniela; Todorova, Iva; Parushev, Stoyan; Tsvetkova, Iva; Najdenski, Hristo; Ubukata, Makoto

    2008-01-01

    The antibacterial activity of synthetic aliphatic and aromatic monoacylglycerols (MAGs) was studied against two human pathogens: Staphylococcus aureus and Escherichia coli. The active compounds inhibited selectively S. aureus. The most active compounds amongst them were those with medium size aliphatic chain and aromatic MAGs with electron withdrawing substituents at the aryl ring. The introduction of one or two-carbon spacer between the aryl ring and the carboxylic function did not influence antibacterial effectiveness. PMID:19004249

  10. Structure-Activity Relationships in Nitro-Aromatic Compounds

    NASA Astrophysics Data System (ADS)

    Vogt, R. A.; Rahman, S.; Crespo-Hernández, C. E.

    Many nitro-aromatic compounds show mutagenic and carcinogenic properties, posing a potential human health risk. Despite this potential health hazard, nitro-aromatic compounds continue to be emitted into ambient air from municipal incinerators, motor vehicles, and industrial power plants. As a result, understanding the structural and electronic factors that influence mutagenicity in nitro-aromatic compounds has been a long standing objective. Progress toward this goal has accelerated over the years, in large part due to the synergistic efforts among toxicology, computational chemistry, and statistical modeling of toxicological data. The concerted influence of several structural and electronic factors in nitro-aromatic compounds makes the development of structure-activity relationships (SARs) a paramount challenge. Mathematical models that include a regression analysis show promise in predicting the mutagenic activity of nitro-aromatic compounds as well as in prioritizing compounds for which experimental data should be pursued. A major challenge of the structure-activity models developed thus far is their failure to apply beyond a subset of nitro-aromatic compounds. Most quantitative structure-activity relationship papers point to statistics as the most important confirmation of the validity of a model. However, the experimental evidence shows the importance of the chemical knowledge in the process of generating models with reasonable applicability. This chapter will concisely summarize the structural and electronic factors that influence the mutagenicity in nitro-aromatic compounds and the recent efforts to use quantitative structure-activity relationships to predict those physicochemical properties.

  11. [Inhibition of aromatics on ammonia-oxidizing activity of sediment].

    PubMed

    Dong, Chun-hong; Hu, Hong-ying; Wei, Dong-bin; Huang, Xia; Qian, Yi

    2004-03-01

    The inhibition of 24 aromatics on ammonia-oxidizing activity of nitrifying bacteria in sediment was measured. The effects of the kind, number and position of substituted groups on ammonia-oxidizing activity of nitrifying bacteria were discussed. The inhibition of mono-substituted benzenes on ammonia-oxidizing activity of nitrifying bacteria were in order of -OH > -NO2 > -NH2 > -Cl > -CH3 > -H. The position of substituted groups of di-substituted benzenes also affected the inhibition, and the inhibitions of dimethylbenzenes(xylene) were in order of meta-> ortho-> para-. The increase in number of substituted group on benzene-ring enhanced the inhibition of aromatics studied in this study on nitrifying bacteria. There was a linear relationship between inhibition (IC50, mumol.L-1) of aromatics on ammonia-oxidizing activity and total electronegativity (sigma E) of aromatics: lgIC50 = 14.72 - 0.91 sigma E.

  12. Synthesis and anti-inflammatory activity of aromatic glucosinolates.

    PubMed

    Vo, Quan V; Trenerry, Craige; Rochfort, Simone; Wadeson, Jenny; Leyton, Carolina; Hughes, Andrew B

    2013-10-01

    Aromatic GLs are important members of the glucosinolate family of compounds because of their potential biological activity and medicinal properties. This study has shown success in the high yielding synthesis of some important aromatic GLs as well as the results of testing for anti-inflammatory properties of the synthetic GLs. 3,4-Dimethoxyphenylglucosinolate was found to be the most active anti-inflammatory of the seven glucosinolates assayed. PMID:23978357

  13. Poly(N-arylenbenzimidazoles) via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor); Smith, Joseph G., Jr. (Inventor)

    1995-01-01

    Novel poly(N-arylenebenzimidazole)s (PNABIs) are prepared by the aromatic nucleophilic displacement reaction of novel di(hydroxyphenyl-N-arylene benzimidazole) monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N,N-dimethylacetamide using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. The di(hydroxyphenyl N-arylenebenzimidazole) monomers are synthesized by reacting phenyl 4-hydroxybenzoate with bis(2-aminoanilino) arylenes in diphenylsulfone. Moderate molecular weight PNABIs of new chemical structures were prepared that exhibit a favorable combination of physical and mechanical properties. The use of the novel di(hydroxyphenyl N-arylenebenzimidazole)s permits a more economical and easier way to prepare PNABIs than previous routes.

  14. Poly(N-arylenebenzimidazole)s via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor); Smith, Jr., Joseph G. (Inventor)

    1996-01-01

    Novel poly(N-arylenebenzimidazole)s (PNABls) are prepared by the aromatic nucleophilic displacement reaction of novel di(hydroxyphenyl-N-arylene benzimidazole) monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N,N-dimethylacetamide using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. The di(hydroxyphenyl-N-arylenebenzimidazole) monomers are synthesized by reacting phenyl-4-hydroxybenzoate with bis(2-aminoanilino)arylenes in diphenylsulfone. Moderate molecular weight PNABIs of new chemical structures were prepared that exhibit a favorable combination of physical and mechanical properties. The use of the novel di(hydroxyphenyI-N-arylenebenzimidazole)s permits a more economical and easier way to prepare PNABIs than previous routes.

  15. Flexibility of active-site gorge aromatic residues and non-gorge aromatic residues in acetylcholinesterase

    SciTech Connect

    Ghattyvenkatakrishna, Pavan K; Uberbacher, Edward C

    2013-01-01

    The presence of an unusually large number of aromatic residues in the active site gorge of acetylcholinesterase has been a topic of great interest. Flexibility of these residues has been suspected to be a key player in controlling ligand traversal in the gorge. This raises the question of whether the over representation of aromatic residues in the gorge implies higher than normal flexibility of those residues. The current study suggests that it does not. Large changes in the hydrophobic cross sectional area due to dihedral oscillations are probably the reason behind their presence in the gorge.

  16. Synthesis and antibacterial activity of pyridinium-tailored aromatic amphiphiles.

    PubMed

    Wang, Peiyi; Gao, Manni; Zhou, Lei; Wu, Zhibing; Hu, Deyu; Hu, Jun; Yang, Song

    2016-02-15

    In this Letter, the antibacterial activities of pyridinium-tailored aromatic amphiphiles were evaluated by turbidimeter tests in vitro. The bioassays revealed that most of the target compounds exhibit appreciable inhibition activities against the plant pathogenic bacteria Xanthomonas oryzae pv. oryzae, Ralstonia solanacearum, and Xanthomonas axonopodis pv. citri. The half-maximal effective concentrations (EC50) of 2-NP-10, 9-AP-10, and 9-AP-7 against these three bacteria were relatively high, which may be ascribed to the favourable hydrophobicity/hydrophilicity balance in these compounds. Our results suggest that pyridinium-tailored aromatic amphiphiles are promising bactericide candidates against plant bacterial diseases. PMID:26832217

  17. Synthesis and antibacterial activity of pyridinium-tailored aromatic amphiphiles.

    PubMed

    Wang, Peiyi; Gao, Manni; Zhou, Lei; Wu, Zhibing; Hu, Deyu; Hu, Jun; Yang, Song

    2016-02-15

    In this Letter, the antibacterial activities of pyridinium-tailored aromatic amphiphiles were evaluated by turbidimeter tests in vitro. The bioassays revealed that most of the target compounds exhibit appreciable inhibition activities against the plant pathogenic bacteria Xanthomonas oryzae pv. oryzae, Ralstonia solanacearum, and Xanthomonas axonopodis pv. citri. The half-maximal effective concentrations (EC50) of 2-NP-10, 9-AP-10, and 9-AP-7 against these three bacteria were relatively high, which may be ascribed to the favourable hydrophobicity/hydrophilicity balance in these compounds. Our results suggest that pyridinium-tailored aromatic amphiphiles are promising bactericide candidates against plant bacterial diseases.

  18. Poly[(μ-3,5-dinitro-benzoato)(μ-3,5-dinitro-benzoic acid)rubidium].

    PubMed

    Miao, Yanqing; Fan, Tao

    2011-08-01

    The asymmetric unit of the title compound, [Rb(C(7)H(3)N(2)O(6))(C(7)H(4)N(2)O(6))](n), comprises an Rb(+) cation, a 3,5-dinitro-benzoate anion and a 3,5-dinitro-benzoic acid ligand. The Rb(+) cation is nine-coordinated by O atoms from four 3,5-dinitro-benzoate anions and three neutral 3,5-dinitro-benzoic acid ligands. The metal atom is firstly linked by four bridging carboxyl groups, forming a binuclear motif, which is further linked by the nitro groups into a two-dimensional framework along the [110] direction. A short O-H⋯O hydrogen bond between two adjacent carboxy/carboxylate groups occurs. PMID:22090832

  19. Impact of dietary aromatic amino acids on osteoclastic activity.

    PubMed

    Refaey, Mona El; Zhong, Qing; Ding, Ke-Hong; Shi, Xing-Ming; Xu, Jianrui; Bollag, Wendy B; Hill, William D; Chutkan, Norman; Robbins, Richard; Nadeau, Hugh; Johnson, Maribeth; Hamrick, Mark W; Isales, Carlos M

    2014-08-01

    We had shown that aromatic amino acid (phenylalanine, tyrosine, and tryptophan) supplementation prevented bone loss in an aging C57BL/6 mice model. In vivo results from the markers of bone breakdown suggested an inhibition of osteoclastic activity or differentiation. To assess osteoclastic differentiation, we examined the effects of aromatic amino acids on early /structural markers as vitronectin receptor, calcitonin receptor, and carbonic anhydrase II as well as, late/functional differentiation markers; cathepsin K and matrix metalloproteinase 9 (MMP-9). Our data demonstrate that the aromatic amino acids down-regulated early and late osteoclastic differentiation markers as measured by real time PCR. Our data also suggest a link between the vitronectin receptor and the secreted cathepsin K that both showed consistent effects to the aromatic amino acid treatment. However, the non-attachment related proteins, calcitonin receptor, and carbonic anhydrase II, demonstrated less consistent effects in response to treatment. Our data are consistent with aromatic amino acids down-regulating osteoclastic differentiation by suppressing remodeling gene expression thus contributing initially to the net increase in bone mass seen in vivo.

  20. Metabolic activation of aromatic amines and azo dyes.

    PubMed

    Bartsch, H

    1981-01-01

    Aromatic amines, amides and nitro compounds are a class of chemicals that produce tumors in a wide variety of tissues in experimental animals, including liver, urinary bladder, forestomach, small intestine, Zymbal's gland, subcutaneous tissue or skin. In man, exposure to some aromatic amines is associated with tumours of the urinary bladder and carcinoma of the renal pelvis. Their biological activity as carcinogens or genotoxic agents is, in all the cases that have been studied in detail, dependent on metabolic activation in vivo, occurring by multiple pathways. Differences in these metabolic pathways may largely account for the differences in tissues and species susceptibilities to cancer induction. Carcinogenicity of aromatic amines or amides is dependent on their oxidation to N-hydroxy derivatives, whilst the carcinogenicity of aromatic nitro compounds is linked to their reduction to hydroxylamines. Further conversion of the N-hydroxylamine or N-hydroxyamide to reactive intermediates can occur in several ways, which include (i) esterification of the N-hydroxy group, (ii) non-enzymic protonation of the nitrogen of the hydroxylamine and (iii) oxidation to a free radical of arylhydroxamic acids. Following generation of such reactive electrophilic intermediates in tissues or cells, macromolecular binding has been observed to nucleic acids and proteins. In many cases, arylamidated and arylaminated products are formed with nucleic acid bases; in the case of the well-studied 2-acetylaminofluorene, nucleophilic atoms of guanine are the predominant site of reaction. Relatively little is known of the structure and biological consequences of DNA adducts formed from other aromatic amines, amides or nitro compounds; more research in these directions is warranted.

  1. 4,6-Dinitro-o-cyclohexyl phenol

    Integrated Risk Information System (IRIS)

    4,6 - Dinitro - o - cyclohexyl phenol ; CASRN 131 - 89 - 5 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments

  2. Lactoperoxidase-catalyzed activation of carcinogenic aromatic and heterocyclic amines.

    PubMed

    Gorlewska-Roberts, Katarzyna M; Teitel, Candee H; Lay, Jackson O; Roberts, Dean W; Kadlubar, Fred F

    2004-12-01

    Lactoperoxidase, an enzyme secreted from the human mammary gland, plays a host defensive role through antimicrobial activity. It has been implicated in mutagenic and carcinogenic activation in the human mammary gland. The potential role of heterocyclic and aromatic amines in the etiology of breast cancer led us to examination of the lactoperoxidase-catalyzed activation of the most commonly studied arylamine carcinogens: 2-amino-1-methyl-6-phenylimidazo[4,5-b]-pyridine (PhIP), benzidine, 4-aminobiphenyl (ABP), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx). In vitro activation was performed with lactoperoxidase (partially purified from bovine milk or human milk) in the presence of hydrogen peroxide and calf thymus DNA. Products formed during enzymatic activation were monitored by HPLC with ultraviolet and radiometric detection. Two of these products were characterized as hydrazo and azo derivatives by means of mass spectrometry. The DNA binding level of 3H- and 14C-radiolabeled amines after peroxidase-catalyzed activation was dependent on the hydrogen peroxide concentration, and the highest levels of carcinogen binding to DNA were observed at 100 microM H2O2. Carcinogen activation and the level of binding to DNA were in the order of benzidine > ABP > IQ > MeIQx > PhIP. One of the ABP adducts was identified, and the level at which it is formed was estimated to be six adducts/10(5) nucleotides. The susceptibility of aromatic and heterocyclic amines for lactoperoxidase-catalyzed activation and the binding levels of activated products to DNA suggest a potential role of lactoperoxidase-catalyzed activation of carcinogens in the etiology of breast cancer.

  3. Effects of ozonation on mutagenic activity of polycyclic aromatic hydrocarbons

    SciTech Connect

    Fouillet, B.; Chambon, P.; Chambon, R. ); Castegnaro, M. ); Weill, N. )

    1991-07-01

    In this study, four polycyclic aromatic hydrocarbons were tested. Benzo(a)pyrene (B(a)P), Chrysene (CH), 7,12-dimethylbenzo(a)-anthracene (DMBA) and 3-methylcholanthrene (MCA) in hexane were treated with ozone to determine the effectiveness of degradation and to evaluate the genetic properties of ozone byproducts. Two types of ozonation were carried out: partial ozonation and total ozonation. The disappearance of parent compounds and the appearance of ozone byproducts were measured by high performance liquid chromatography (HPLC) coupled with spectrofluorimetry and U.V. spectrophotometry. Plate incorporation mutagenicity assay, using a Salmonella typhimurium strain, was used to test the ozone byproducts with and without metabolic activation.

  4. 4,6-Dinitro­pyrogallol

    PubMed Central

    Neis, Christian; Merten, Günter J.; Hegetschweiler, Kaspar

    2012-01-01

    In the title mol­ecule, C6H4N2O7, the two nitro groups are tilted with respect to the aromatic ring by 11.2 (1) and 10.9 (1)°. All three hy­droxy groups are involved in the formation of bifurcated intra- and inter­molecular O—H⋯O hydrogen bonds. The crystal packing exhibits short O⋯O distances of 2.823 (2) Å between two O atoms of the nitro groups. PMID:22412586

  5. 3,3-Dinitro­azetidinium chloride

    PubMed Central

    Yan, Biao; Li, Hong-Ya; Zhao, Ning-Ning; Li, Jie; Ma, Hai-Xia

    2012-01-01

    In the title gem-dinitro­azetidinium chloride salt, C3H6N3O4 +·Cl−, the cations and anions lie on a mirror plane. The azetidine ring is virtually planar, with a mean deviation from the plane of 0.0569 Å. The dihedral angle between the two nitro groups is 90.00 (5)°. In the crystal, the ions are linked by N—H⋯Cl interactions, forming a chain along the c-axis direction, and C—H⋯O inter­actions, forming a layer parallel to (010). PMID:23476208

  6. Antibacterial activity of phenolic compounds and aromatic alcohols.

    PubMed

    Lucchini, J J; Corre, J; Cremieux, A

    1990-05-01

    The antibacterial properties of phenolic compounds and aromatic alcohols (growth inhibition, lethal effect and cytological damage) were investigated. The role of protein and RNA synthesis in the bactericidal action was also determined. All compounds tested demonstrated lethal properties and the ability to alter membranes, especially in Gram-negative bacteria. Efficacious concentrations, however, varied greatly among the compounds. These data corroborate previous findings which suggest that the mechanism of action of these compounds is related to their lipophilia. Moreover, since it was demonstrated that the lethal effect of two aromatic alcohols (phenethyl alcohol and benzyl alcohol) stops when protein synthesis is inhibited, it is likely that both possess specific mechanisms of action.

  7. Annulation of aromatic imines via directed C-H bond activation.

    PubMed

    Thalji, Reema K; Ahrendt, Kateri A; Bergman, Robert G; Ellman, Jonathan A

    2005-08-19

    A directed C-H bond activation approach to the synthesis of indans, tetralins, dihydrofurans, dihydroindoles, and other polycyclic aromatic compounds is presented. Cyclization of aromatic ketimines and aldimines containing alkenyl groups tethered at the meta position relative to the imine directing group has been achieved using (PPh3)3RhCl (Wilkinson's catalyst). The cyclization of a range of aromatic ketimines and aldimines provides bi- and tricyclic ring systems with good regioselectivity. Different ring sizes and substitution patterns can be accessed through the coupling of monosubstituted, 1,1- or 1,2-disubstituted, and trisubstituted alkenes bearing both electron-rich and electron-deficient functionality.

  8. Toxicity of N-substituted aromatics to acetoclastic methanogenic activity in granular sludge.

    PubMed Central

    Donlon, B A; Razo-Flores, E; Field, J A; Lettinga, G

    1995-01-01

    N-substituted aromatics are important priority pollutants entering the environment primarily through anthropogenic activities associated with the industrial production of dyes, explosives, pesticides, and pharmaceuticals. Anaerobic treatment of wastewaters discharged by these industries could potentially be problematical as a result of the high toxicity of N-substituted aromatics. The objective of this study was to examine the structure-toxicity relationships of N-substituted aromatic compounds to acetoclastic methanogenic bacteria. The toxicity was assayed in serum flasks by measuring methane production in granular sludge. Unacclimated cultures were used to minimize the biotransformation of the toxic organic chemicals during the test. The nature and the degree of the aromatic substitution were observed to have a profound effect on the toxicity of the test compound. Nitroaromatic compounds were, on the average, over 500-fold more toxic than their corresponding aromatic amines. Considering the facile reduction of nitro groups by anaerobic microorganisms, a dramatic detoxification of nitroaromatics towards methanogens can be expected to occur during anaerobic wastewater treatment. While the toxicity exerted by the N-substituted aromatic compounds was closely correlated with compound apolarity (log P), it was observed that at any given log P, N-substituted phenols had a toxicity that was 2 orders of magnitude higher than that of chlorophenols and alkylphenols. This indicates that toxicity due to the chemical reactivity of nitroaromatics is much more important than partitioning effects in bacterial membranes. PMID:8526501

  9. Reductive carbonylation of aromatic nitro compounds

    SciTech Connect

    Wehman, P.; Kamer, P.C.J.; Leeuwen, P.W.N.M. van

    1995-12-31

    In the reductive carbonylation of aromatic nitro compounds carbamates and isocyanates are prepared through a direct reaction between the nitro group and CO under the influence of a catalyst. This route avoids the major disadvantages of the traditional process for the production of the industrially important isocyanates and carbamates. The authors have developed a stable, active, and rather selective homogeneous palladium catalyst for the reductive carbonylation of the nitro substrate. Best results were obtained with Pd-phenanthroline complexes in which the ligands bear moderately donating substituents. Noncoordinating anions in the catalyst complex are clearly preferable. The highest activity was reached with the Pd(4,7-Me{sub 2}-1,10-phen){sub 2}(OTf){sub 2} catalyst complex (t.o.f. = 311 mol/mol/h, selectivity toward the desired carbamate = 84%). With the Pd(1,10-phenanthroline){sub 2}(OTf){sub 2} catalyst complex, the authors studied the scope of the reaction in order to prepare a wide range of functionalized carbamates for the fine chemistry. During this study, it was found that a remarkable improvement of the catalytic activity and selectivity on addition of a benzoic acid (t.o.f. > 365 mol/mol/h, selectivity toward carbamate = 94%). In the presence of 4-chlorobenzoic acid even aromatic dinitro compounds could be converted easily, resulting in the best results reported ever for the conversion of 1,4-dinitrobenzene into the corresponding dicarbamate (t.o.f. = 73 mol/mol/h, selectivity toward the dicarbamate = 86%).

  10. Preparation of 1,1'-dinitro-3,3'-azo-1,2,4-triazole. [1,1'-dinitro-3,3'-azo-1,2,4-triazole

    DOEpatents

    Lee, K.Y.

    1985-03-05

    A new high density composition of matter, 1,1'-dinitro-3,3'-azo-1,2,4-triazole, has been synthesized using inexpensive, commonly available compounds. This compound has been found to be an explosive, and its use as a propellant is anticipated. 1 fig., 1 tab.

  11. Poly[(μ(5)-3,5-dinitro-benzoato)rubidium].

    PubMed

    Miao, Yanqing; Zhang, Xiaoqing; Liu, Chunye

    2011-07-01

    The asymmetric unit of the title compound, [Rb(C(7)H(3)N(2)O(6))](n), comprises an Rb cation and a 3,5-dinitro-benzoate anion. The Rb cation is eight-coordinated by O atoms from five 3,5-dinitro-benzoate anions. On the other hand, each 3,5-dinitro-benzoate anion links five Rb cations with the carboxyl-ate groups as μ(3)-bridging. The metal atom is firstly linked by the carboxyl-ate groups into a chain along the c-axis direction, which is further linked by bonds between the Rb and nitro O atoms, giving a three-dimensional framework. PMID:21836829

  12. Poly[μ(3)-aqua-μ(2)-2,4-dinitro-phenolato-rubidium(I)].

    PubMed

    Yang, Zhangqin; Hu, Mancheng; Wang, Xiuhang

    2007-01-01

    The asymmetric unit of the title compound, [Rb(C(6)H(3)N(2)O(5))(H(2)O)](n), comprises a rubidium cation, a 2,4-dinitro-phenoxide anion and a water mol-ecule. The Rb(+) cation is 11-coordinated by O atoms from 2,4-dinitro-phenolate anions and water mol-ecules. The metal centre is firstly coordinated by two μ(3)-H(2)O to form a one-dimensional ladder-shaped unit, [Rb(2)(μ(3)-H(2)O)(2)], which is further linked by 2,4-dinitro-phenolate to give the three-dimensional framework of the title compound. The crystal structure involves O-H⋯O hydrogen bonds. PMID:21200571

  13. Antifungal activities of selected aromatic plants growing wild in Greece.

    PubMed

    Soković, M; Tzakou, O; Pitarokili, D; Couladis, M

    2002-10-01

    Essential oils of Origanum onites, Satureja thymbra, Salvia fruticosa (Greek sage), and Salvia pomifera subsp. calycina plants growing wild in Greece and their components carvacrol, camphor, and 1,8-cineole, were assayed for antifungal activity against 13 fungal species. Among the fungi tested were food poisoning, plant, animals and human pathogenic species. The oils presented various degrees of inhibition against all the fungi investigated. The highest and broadest activity was shown by the carvacrol content oils (O. onites and S. thymbra), while the oil of sage was the least effective. Carvacrol exhibited the highest and 1,8-cineole the lowest level of antifungal activity among the components tested. PMID:12428445

  14. Identification of primary aromatic amines in mutagenically active subfractions from coal liquefaction materials.

    PubMed

    Wilson, B W; Pelroy, R; Cresto, J T

    1980-11-01

    Gas-chromatographic mass spectral (GCMS) analyses were performed on mutagenically active components from the basic, basic tar and neutral tar subfractions of a coal-derived liquid heavy distillate. The latter material is a component fraction of an experimental oil produced in a solvent refined coal process (SRC II) pilot plant. Mutagenicity was determined with the Ames/Salmonella assay system. Thin-layer chromatography (TLC) was used to separate mutagenically active components of the basic, basic tar and neutral tar fractions from some of the other compounds contained in these complex materials. For the 3 fractions tested, mutagenic activity was localized in approx. the same TLC regions, with relative mobilities (Rf) ranging from 0.1 to 0.3. GCMS analysis of the TLC regions showed that the concentrations of primary aromatic amines, as obtained by measuring peak areas for the (M + 1)+ ion as formed in the chemical ionization mode, followed essentially the same distribution as the mutagenic activity. Primary aromatic amines identified in the active regions included aminonaphthalenes, aminoanthracenes, aminophenanthrenes, aminopyrenes and aminochrysenes. With the exception of small amounts of aminonaphthalene, primary aromatic amines were not found in TLC regions that lacked mutagenic activity.

  15. Palladium-catalyzed regioselective intramolecular coupling of o-carborane with aromatics via direct cage B-H activation.

    PubMed

    Quan, Yangjian; Xie, Zuowei

    2015-03-18

    Palladium-catalyzed intramolecular coupling of o-carborane with aromatics via direct cage B-H bond activation has been achieved, leading to the synthesis of a series of o-carborane-functionalized aromatics in high yields with excellent regioselectivity. In addition, the site selectivity can also be tuned by the substituents on cage carbon atom.

  16. Synthesis and structural characterization of 3,5-dinitro-1,2,4-triazolates.

    PubMed

    Haiges, R; Bélanger-Chabot, G; Kaplan, S M; Christe, K O

    2015-02-21

    Salts of 3,5-dinitro-1H-1,2,4-triazole, a building block for energetic materials, have been prepared and fully characterized. Most of the studied salts exhibit high thermal stability and very low shock and friction sensitivities. 3,5-Dinitro-1,2,4-triazolates with the nitrogen-rich ammonium, guanidinium, aminoguanidinium, and aminotetrazolium cations are energetic and have potential for energetic material applications. Salts containing alkali, alkali earth metal, and silver cations exhibit coloured emissions upon combustion while salts with large organic cations such as PPh4(+) and (Ph3P)2N(+) are highly insensitive and can be easily crystallized.

  17. Some 1-(diorganooxyphosphonyl)methyl-2,4- and -2,6-dinitro-benzenes

    NASA Technical Reports Server (NTRS)

    Mikroyannidis, John A. (Inventor); Kourtides, Demetrius A. (Inventor)

    1989-01-01

    1-(Diorgano oxyphosphonyl) methyl) 2,4- and 2,6-dinitro- and diamino benzenes are prepared by nitrating an (organophosphonyl)methly benzene to produce the dinitro compounds which are then reduced to the diamino compounds. The organo group (alkyl, haloalkyl, aryl) on the phosphorus may be removed to give the free acids, (HO)2P(double bond O) single bond. The diamino compounds may be polymerized with dianhydrides or diacyl halides to produce fire and flame resistant polymers which are useful in the manufacture of aircraft structures.

  18. Quantitative structure-activity relationship for toxicity of ionic liquids to Daphnia magna: aromaticity vs. lipophilicity.

    PubMed

    Roy, Kunal; Das, Rudra Narayan; Popelier, Paul L A

    2014-10-01

    Water solubility of ionic liquids (ILs) allows their dispersion into aquatic systems and raises concerns on their pollutant potential. Again, lipophilicity can contribute to the toxicity of ILs due to increased ability of the compounds to cross lipoidal bio-membranes. In the present work, we have performed statistical model development for toxicity of a set of ionic liquids to Daphnia magna, a widely accepted model organism for toxicity testing, using computed lipophilicity, atom-type fragment, quantum topological molecular similarity (QTMS) and extended topochemical atom (ETA) descriptors. The models have been developed and validated in accordance with the Organization for Economic Co-operation and Development (OECD) guidelines for quantitative structure-activity relationships (QSARs). The best partial least squares (PLS) model outperforms the previously reported multiple linear regression (MLR) model in statistical quality and predictive ability (R(2)=0.955, Q(2)=0.917, Rpred(2)=0.848). In this work, the ETA descriptors show importance of branching and aromaticity while the QTMS descriptor ellipticity efficiently shows which compounds are influential in the data set, with reference to the model. While obvious importance of lipophilicity is evident from the models, the best model clearly shows the importance of aromaticity suggesting that more lipophilic ILs with less toxicity may be designed by avoiding aromaticity, nitrogen atoms and increasing branching in the cationic structure. The developed quantitative models are in consonance with the recent hypothesis of importance of aromaticity for toxicity of ILs.

  19. Estrogenic Activity of Mineral Oil Aromatic Hydrocarbons Used in Printing Inks

    PubMed Central

    Tarnow, Patrick; Hutzler, Christoph; Grabiger, Stefan; Schön, Karsten; Tralau, Tewes; Luch, Andreas

    2016-01-01

    The majority of printing inks are based on mineral oils (MOs) which contain complex mixtures of saturated and aromatic hydrocarbons. Consumer exposure to these oils occurs either through direct skin contacts or, more frequently, as a result of MO migration into the contents of food packaging that was made from recycled newspaper. Despite this ubiquitous and frequent exposure little is known about the potential toxicological effects, particularly with regard to the aromatic MO fractions. From a toxicological point of view the huge amount of alkylated and unsubstituted compounds therein is reason for concern as they can harbor genotoxicants as well as potential endocrine disruptors. The aim of this study was to assess both the genotoxic and estrogenic potential of MOs used in printing inks. Mineral oils with various aromatic hydrocarbon contents were tested using a battery of in vitro assays selected to address various endpoints such as estrogen-dependent cell proliferation, activation of estrogen receptor α or transcriptional induction of estrogenic target genes. In addition, the comet assay has been applied to test for genotoxicity. Out of 15 MOs tested, 10 were found to potentially act as xenoestrogens. For most of the oils the effects were clearly triggered by constituents of the aromatic hydrocarbon fraction. From 5 oils tested in the comet assay, 2 showed slight genotoxicity. Altogether it appears that MOs used in printing inks are potential endocrine disruptors and should thus be assessed carefully to what extent they might contribute to the total estrogenic burden in humans. PMID:26771904

  20. Structure-Activity Relationships for Rates of Aromatic Amine Oxidation by Manganese Dioxide.

    PubMed

    Salter-Blanc, Alexandra J; Bylaska, Eric J; Lyon, Molly A; Ness, Stuart C; Tratnyek, Paul G

    2016-05-17

    New energetic compounds are designed to minimize their potential environmental impacts, which includes their transformation and the fate and effects of their transformation products. The nitro groups of energetic compounds are readily reduced to amines, and the resulting aromatic amines are subject to oxidation and coupling reactions. Manganese dioxide (MnO2) is a common environmental oxidant and model system for kinetic studies of aromatic amine oxidation. In this study, a training set of new and previously reported kinetic data for the oxidation of model and energetic-derived aromatic amines was assembled and subjected to correlation analysis against descriptor variables that ranged from general purpose [Hammett σ constants (σ(-)), pKas of the amines, and energies of the highest occupied molecular orbital (EHOMO)] to specific for the likely rate-limiting step [one-electron oxidation potentials (Eox)]. The selection of calculated descriptors (pKa, EHOMO, and Eox) was based on validation with experimental data. All of the correlations gave satisfactory quantitative structure-activity relationships (QSARs), but they improved with the specificity of the descriptor. The scope of correlation analysis was extended beyond MnO2 to include literature data on aromatic amine oxidation by other environmentally relevant oxidants (ozone, chlorine dioxide, and phosphate and carbonate radicals) by correlating relative rate constants (normalized to 4-chloroaniline) to EHOMO (calculated with a modest level of theory). PMID:27074054

  1. Activity of nitro-polynuclear aromatic hydrocarbons in the sister chromatid exchange assay with and without metabolic activation.

    PubMed

    Nachtman, J P; Wolff, S

    1982-01-01

    Nitro-polynuclear aromatic hydrocarbons are found in diesel particulates. These compounds are potent mutagens in the Ames test. To determine whether nitro-polynuclear aromatic hydrocarbons are active in a mammalian cell assay, 1-nitropyrene, 1,8-dinitropyrene, 2-nitrofluorene, and 4-nitrobiphenyl were incubated with cultures of Chinese hamster ovary cells. The frequency of sister chromatid exchange (SCE) was measured in the presence and absence of rat liver S-9 mix. The addition of S-9 mix resulted in a large increase in the SCEs induced by all four compounds. PMID:7067667

  2. Activity of nitro-polynuclear aromatic hydrocarbons in the sister chromatid exchange assay with and without metabolic activation. [Hamsters

    SciTech Connect

    Nachtman, J.P.; Wolff, S.

    1982-01-01

    Nitro-polynuclear aromatic hydrocarbons are found in diesel particulates.These compounds are potent mutagens in the Ames test. To determine whether nitro-polynuclear aromatic hydrocarbons are active in a mammalian cell assay, 1-nitropyrene, 1,8-dinitropyrene, 2-nitrofluorene, and 4-nitrobiphenyl were incubated with cultures of Chinese hamster ovary cells. The frequency of sister chromatic exchange (SCE) was measured in the presence and absence of rat liver S-9 mix. The addition of S-9 mix resulted in a large increase in the SCEs induced by all four compounds.

  3. Perchlorate Reductase Is Distinguished by Active Site Aromatic Gate Residues.

    PubMed

    Youngblut, Matthew D; Tsai, Chi-Lin; Clark, Iain C; Carlson, Hans K; Maglaqui, Adrian P; Gau-Pan, Phonchien S; Redford, Steven A; Wong, Alan; Tainer, John A; Coates, John D

    2016-04-22

    Perchlorate is an important ion on both Earth and Mars. Perchlorate reductase (PcrAB), a specialized member of the dimethylsulfoxide reductase superfamily, catalyzes the first step of microbial perchlorate respiration, but little is known about the biochemistry, specificity, structure, and mechanism of PcrAB. Here we characterize the biophysics and phylogeny of this enzyme and report the 1.86-Å resolution PcrAB complex crystal structure. Biochemical analysis revealed a relatively high perchlorate affinity (Km = 6 μm) and a characteristic substrate inhibition compared with the highly similar respiratory nitrate reductase NarGHI, which has a relatively much lower affinity for perchlorate (Km = 1.1 mm) and no substrate inhibition. Structural analysis of oxidized and reduced PcrAB with and without the substrate analog SeO3 (2-) bound to the active site identified key residues in the positively charged and funnel-shaped substrate access tunnel that gated substrate entrance and product release while trapping transiently produced chlorate. The structures suggest gating was associated with shifts of a Phe residue between open and closed conformations plus an Asp residue carboxylate shift between monodentate and bidentate coordination to the active site molybdenum atom. Taken together, structural and mutational analyses of gate residues suggest key roles of these gate residues for substrate entrance and product release. Our combined results provide the first detailed structural insight into the mechanism of biological perchlorate reduction, a critical component of the chlorine redox cycle on Earth.

  4. Perchlorate Reductase Is Distinguished by Active Site Aromatic Gate Residues.

    PubMed

    Youngblut, Matthew D; Tsai, Chi-Lin; Clark, Iain C; Carlson, Hans K; Maglaqui, Adrian P; Gau-Pan, Phonchien S; Redford, Steven A; Wong, Alan; Tainer, John A; Coates, John D

    2016-04-22

    Perchlorate is an important ion on both Earth and Mars. Perchlorate reductase (PcrAB), a specialized member of the dimethylsulfoxide reductase superfamily, catalyzes the first step of microbial perchlorate respiration, but little is known about the biochemistry, specificity, structure, and mechanism of PcrAB. Here we characterize the biophysics and phylogeny of this enzyme and report the 1.86-Å resolution PcrAB complex crystal structure. Biochemical analysis revealed a relatively high perchlorate affinity (Km = 6 μm) and a characteristic substrate inhibition compared with the highly similar respiratory nitrate reductase NarGHI, which has a relatively much lower affinity for perchlorate (Km = 1.1 mm) and no substrate inhibition. Structural analysis of oxidized and reduced PcrAB with and without the substrate analog SeO3 (2-) bound to the active site identified key residues in the positively charged and funnel-shaped substrate access tunnel that gated substrate entrance and product release while trapping transiently produced chlorate. The structures suggest gating was associated with shifts of a Phe residue between open and closed conformations plus an Asp residue carboxylate shift between monodentate and bidentate coordination to the active site molybdenum atom. Taken together, structural and mutational analyses of gate residues suggest key roles of these gate residues for substrate entrance and product release. Our combined results provide the first detailed structural insight into the mechanism of biological perchlorate reduction, a critical component of the chlorine redox cycle on Earth. PMID:26940877

  5. Asymmetric Intramolecular Alkylation of Chiral Aromatic Imines via Catalytic C-H Bond Activation

    SciTech Connect

    Watzke, Anja; Wilson, Rebecca; O'Malley, Steven; Bergman, Robert; Ellman, Jonathan

    2007-04-16

    The asymmetric intramolecular alkylation of chiral aromatic aldimines, in which differentially substituted alkenes are tethered meta to the imine, was investigated. High enantioselectivities were obtained for imines prepared from aminoindane derivatives, which function as directing groups for the rhodium-catalyzed C-H bond activation. Initial demonstration of catalytic asymmetric intramolecular alkylation also was achieved by employing a sterically hindered achiral imine substrate and catalytic amounts of a chiral amine.

  6. Preparation of 1,1'-dinitro-3,3'-azo-1,2,4-triazole

    DOEpatents

    Lee, Kien-Yin

    1986-01-01

    A new high density composition of matter, 1,1'-dinitro-3,3'-azo-1,2,4-triazole, has been synthesized using inexpensive, commonly available compounds. This compound has been found to be an explosive, and its use as a propellant is anticipated.

  7. Design, synthesis, and biological activities of aromatic gossypol Schiff base derivatives.

    PubMed

    Li, Ling; Li, Zheng; Wang, Kailiang; Zhao, Sheng; Feng, Jiming; Li, Jiarui; Yang, Peiwen; Liu, Yuxiu; Wang, Lizhong; Li, Yongqiang; Shang, Hui; Wang, Qingmin

    2014-11-19

    A series of aromatic gossypol Schiff bases have been successfully synthesized via a feasible chemical modification. The antiviral activity against tobacco mosaic virus (TMV) of these gossypol Schiff bases has been tested for the first time. The bioassay studies indicated most of these derivatives exhibited excellent anti-TMV activity, in which o-trifluoromethylaniline Schiff base (19) displayed the best antiviral activities. Furthermore, compound 19 exhibited an eminent anti-TMV effect in the field and low toxicity to mice. These results suggest it is a promising candidate for the inhibitor of plant virus.

  8. New lipophilic piceatannol derivatives exhibiting antioxidant activity prepared by aromatic hydroxylation with 2-iodoxybenzoic acid (IBX).

    PubMed

    Bernini, Roberta; Barontini, Maurizio; Spatafora, Carmela

    2009-01-01

    Piceatannol (E-3,5,3',4'-tetrahydroxystilbene) is a phytoalexin synthesized in grapes in response to stress conditions. It exhibits strong antioxidant and antileukaemic activities due to the presence of the catechol moiety. To modify some physical properties like solubility, and miscibility in non-aqueous media some new previously unreported piceatannol derivatives having lipophilic chains on the A-ring were prepared in good yields by a simple and efficient procedure. The key step was a chemo- and regioselective aromatic hydroxylation with 2-iodoxybenzoic acid (IBX). The new compounds showed antioxidant activity and seemed promising for possible applications as multifunctional emulsifiers in food, cosmetic and pharmaceutical fields.

  9. The biochemical mechanisms of the plant activation of promutagenic aromatic amines

    SciTech Connect

    Wagner, E.D.; Verdier, M.M.; Plewa, M.J. )

    1990-01-01

    Using specific monooxygenase and oxidase inhibitors in a plant cell/microbe coincubation assay, the biochemical mechanisms of the plant activation of two aromatic amines were compared. The biological endpoints included mutation induction, inhibition of mutagenicity, viability of the plant cells (activating system), and viability of the microbial cells. The activation of m-phenylenediamine by TX1 cells was mediated by enzyme systems that were inhibited by diethyldithiocarbamate, potassium cyanide, methimazole, (+)-catechin or acetaminophen. The inhibition by metyrapone was attended by toxicity in the plant cells. These data implicate a TX1 cell peroxidase and a FAD-dependent monoxygenase in the plant activation of m-phenylenediamine. The TX1 cell activation of 2-aminofluorene was inhibited by diethyldithiocarbamate, 7,8-benzoflavone, acetaminophen or (+)-catechin.

  10. Antimicrobial activity of essential oils from Mediterranean aromatic plants against several foodborne and spoilage bacteria.

    PubMed

    Silva, Nuno; Alves, Sofia; Gonçalves, Alexandre; Amaral, Joana S; Poeta, Patrícia

    2013-12-01

    The antimicrobial activity of essential oils extracted from a variety of aromatic plants, often used in the Portuguese gastronomy was studied in vitro by the agar diffusion method. The essential oils of thyme, oregano, rosemary, verbena, basil, peppermint, pennyroyal and mint were tested against Gram-positive (Listeria monocytogenes, Clostridium perfringens, Bacillus cereus, Staphylococcus aureus, Enterococcus faecium, Enterococcus faecalis, and Staphylococcus epidermidis) and Gram-negative strains (Salmonella enterica, Escherichia coli, and Pseudomonas aeruginosa). For most essential oils examined, S. aureus, was the most susceptible bacteria, while P. aeruginosa showed, in general, least susceptibility. Among the eight essential oils evaluated, thyme, oregano and pennyroyal oils showed the greatest antimicrobial activity, followed by rosemary, peppermint and verbena, while basil and mint showed the weakest antimicrobial activity. Most of the essential oils considered in this study exhibited a significant inhibitory effect. Thyme oil showed a promising inhibitory activity even at low concentration, thus revealing its potential as a natural preservative in food products against several causal agents of foodborne diseases and food spoilage. In general, the results demonstrate that, besides flavoring the food, the use of aromatic herbs in gastronomy can also contribute to a bacteriostatic effect against pathogens.

  11. Antimicrobial activity of essential oils from Mediterranean aromatic plants against several foodborne and spoilage bacteria.

    PubMed

    Silva, Nuno; Alves, Sofia; Gonçalves, Alexandre; Amaral, Joana S; Poeta, Patrícia

    2013-12-01

    The antimicrobial activity of essential oils extracted from a variety of aromatic plants, often used in the Portuguese gastronomy was studied in vitro by the agar diffusion method. The essential oils of thyme, oregano, rosemary, verbena, basil, peppermint, pennyroyal and mint were tested against Gram-positive (Listeria monocytogenes, Clostridium perfringens, Bacillus cereus, Staphylococcus aureus, Enterococcus faecium, Enterococcus faecalis, and Staphylococcus epidermidis) and Gram-negative strains (Salmonella enterica, Escherichia coli, and Pseudomonas aeruginosa). For most essential oils examined, S. aureus, was the most susceptible bacteria, while P. aeruginosa showed, in general, least susceptibility. Among the eight essential oils evaluated, thyme, oregano and pennyroyal oils showed the greatest antimicrobial activity, followed by rosemary, peppermint and verbena, while basil and mint showed the weakest antimicrobial activity. Most of the essential oils considered in this study exhibited a significant inhibitory effect. Thyme oil showed a promising inhibitory activity even at low concentration, thus revealing its potential as a natural preservative in food products against several causal agents of foodborne diseases and food spoilage. In general, the results demonstrate that, besides flavoring the food, the use of aromatic herbs in gastronomy can also contribute to a bacteriostatic effect against pathogens. PMID:23444311

  12. Antitumor and antiparasitic activity of novel ruthenium compounds with polycyclic aromatic ligands.

    PubMed

    Miserachs, Helena Guiset; Cipriani, Micaella; Grau, Jordi; Vilaseca, Marta; Lorenzo, Julia; Medeiros, Andrea; Comini, Marcelo A; Gambino, Dinorah; Otero, Lucía; Moreno, Virtudes

    2015-09-01

    Five novel ruthenium(II)-arene complexes with polycyclic aromatic ligands were synthesized, comprising three compounds of the formula [RuCl(η(6)-p-cym)(L)][PF6], where p-cym = 1-isopropyl-4-methylbenzene and L are the bidentate aromatic ligands 1,10-phenanthroline-5,6-dione, 1, 5-amine-1,10-phenanthroline, 4, or 5,6-epoxy-5,6-dihydro-phenanthroline, 5. In the other two complexes [RuCl2(η(6)-p-cym)(L')], the metal is coordinated to a monodentate ligand L', where L' is phenanthridine, 2, or 9-carbonylanthracene, 3. All compounds were fully characterized by mass spectrometry and elemental analysis, as well as NMR and IR spectroscopic techniques. Obtained ruthenium compounds as well as their respective ligands were tested for their antiparasitic and antitumoral activities. Even though all compounds showed lower Trypanosoma brucei activity than the free ligands, they also resulted less toxic on mammalian cells. Cytotoxicity assays on HL60 cells showed a moderate antitumoral activity for all ruthenium compounds. Compound 1 was the most potent antitumoral (IC50 = 1.26±0.78 μM) and antiparasitic (IC50 = 0.19 ± 0.05 μM) agent, showing high selectivity towards the parasites (selectivity index >100). As complex 1 was the most promising antitumoral compound, its interaction with ubiquitin as potential target was also studied. In addition, obtained ruthenium compounds were found to bind DNA, and they are thought to interact with this macromolecule mainly through intercalation of the aromatic ligand.

  13. Adsorption of aromatic compounds from the biodegradation of azo dyes on activated carbon

    NASA Astrophysics Data System (ADS)

    Faria, P. C. C.; Órfão, J. J. M.; Figueiredo, J. L.; Pereira, M. F. R.

    2008-03-01

    The adsorption of three selected aromatic compounds (aniline, sulfanilic acid and benzenesulfonic acid) on activated carbons with different surface chemical properties was investigated at different solution pH. A fairly basic commercial activated carbon was modified by means of chemical treatment with HNO 3, yielding an acid activated carbon. The textural properties of this sample were not significantly changed after the oxidation treatment. Equilibrium isotherms of the selected compounds on the mentioned samples were obtained and the results were discussed in relation to their surface chemistry. The influence of electrostatic and dispersive interactions involved in the uptake of the compounds studied was evaluated. The Freundlich model was used to fit the experimental data. Higher uptakes are attained when the compounds are present in their molecular form. In general, adsorption was disfavoured by the introduction of oxygen-containing groups on the surface of the activated carbon.

  14. Improvement of aromatic thiol release through the selection of yeasts with increased β-lyase activity.

    PubMed

    Belda, Ignacio; Ruiz, Javier; Navascués, Eva; Marquina, Domingo; Santos, Antonio

    2016-05-16

    The development of a selective medium for the rapid differentiation of yeast species with increased aromatic thiol release activity has been achieved. The selective medium was based on the addition of S-methyl-l-cysteine (SMC) as β-lyase substrate. In this study, a panel of 245 strains of Saccharomyces cerevisiae strains was tested for their ability to grow on YCB-SMC medium. Yeast strains with an increased β-lyase activity grew rapidly because of their ability to release ammonium from SMC in comparison to others, and allowed for the easy isolation and differentiation of yeasts with promising properties in oenology, or another field, for aromatic thiol release. The selective medium was also helpful for the discrimination between those S. cerevisiae strains, which present a common 38-bp deletion in the IRC7 sequence (present in around 88% of the wild strains tested and are likely to be less functional for 4-mercapto-4-methylpentan-2-one (4MMP) production), and those S. cerevisiae strains homozygous for the full-length IRC7 allele. The medium was also helpful for the selection of non-Saccharomyces yeasts with increased β-lyase activity. Based on the same medium, a highly sensitive, reproducible and non-expensive GC-MS method for the evaluation of the potential volatile thiol release by different yeast isolates was developed. PMID:26971012

  15. Improvement of aromatic thiol release through the selection of yeasts with increased β-lyase activity.

    PubMed

    Belda, Ignacio; Ruiz, Javier; Navascués, Eva; Marquina, Domingo; Santos, Antonio

    2016-05-16

    The development of a selective medium for the rapid differentiation of yeast species with increased aromatic thiol release activity has been achieved. The selective medium was based on the addition of S-methyl-l-cysteine (SMC) as β-lyase substrate. In this study, a panel of 245 strains of Saccharomyces cerevisiae strains was tested for their ability to grow on YCB-SMC medium. Yeast strains with an increased β-lyase activity grew rapidly because of their ability to release ammonium from SMC in comparison to others, and allowed for the easy isolation and differentiation of yeasts with promising properties in oenology, or another field, for aromatic thiol release. The selective medium was also helpful for the discrimination between those S. cerevisiae strains, which present a common 38-bp deletion in the IRC7 sequence (present in around 88% of the wild strains tested and are likely to be less functional for 4-mercapto-4-methylpentan-2-one (4MMP) production), and those S. cerevisiae strains homozygous for the full-length IRC7 allele. The medium was also helpful for the selection of non-Saccharomyces yeasts with increased β-lyase activity. Based on the same medium, a highly sensitive, reproducible and non-expensive GC-MS method for the evaluation of the potential volatile thiol release by different yeast isolates was developed.

  16. Tumour-promoting activity of polycyclic aromatic hydrocarbons and their oxygenated or nitrated derivatives.

    PubMed

    Misaki, Kentaro; Takamura-Enya, Takeji; Ogawa, Hideoki; Takamori, Kenji; Yanagida, Mitsuaki

    2016-03-01

    Various types of polycyclic aromatic compounds (PACs) in diesel exhaust particles are thought to contribute to carcinogenesis in mammals. Although the carcinogenicity, mutagenicity and tumour-initiating activity of these compounds have been evaluated, their tumour-promoting activity is unclear. In the present study, to determine the tumour-inducing activity of PACs, including previously known mutagenic compounds in atmospheric environments, a transformation assay for promoting activity mediated by the release of contact inhibition was conducted for six polycyclic aromatic hydrocarbons (PAHs), seven oxygenated PAHs (oxy-PAHs) and seven nitrated PAHs (nitro-PAHs) using mouse embryonic fibroblast cells transfected with the v-Ha-ras gene (Bhas 42 cells). Of these, two PAHs [benzo[k]fluoranthene (B[k]FA) and benzo[b]fluoranthene (B[b]FA)], one oxy-PAH [6H-benzo[cd]pyren-6-one (BPO)] and two nitro-PAHs (3-nitro-7H-benz[de]anthracen-7-one and 6-nitrochrysene) were found to exhibit particularly powerful tumour-promoting activity (≥10 foci following exposure to <100nM). In addition, clear mRNA expression of CYP1A1, which is associated with aryl hydrocarbon receptor (AhR)-mediated activation, was observed following the exposure of cells to two PAHs (B[k]FA and B[b]FA) and three oxy-PAHs (1,2-naphthoquinone, 11H-benzo[b]fluoren-11-one and BPO). Further, an HO-1 antioxidant response activation was observed following exposure to B[k]FA, B[b]FA and BPO, suggesting that the induction of tumour-promoting activity in these compounds is correlated with the dysfunction of signal transduction via AhR-mediated responses and/or oxidative stress responses.

  17. Poly[(μ-2-hy-droxy-3,5-dinitro-benzoato)rubidium].

    PubMed

    Meng, Yan

    2011-04-01

    The asymmetric unit of the title compound, [Rb(C(7)H(3)N(2)O(7))](n), comprises an Rb(+) cation and a 3,5-dinitro-salicylate ligand. The Rb(+) cation is 10-coordinated by O atoms from eight 3,5-dinitro-salicylate anions and is linked by three μ(2)-O atoms, forming a zigzag chain along the b-axis direction, which is further linked by the phenyl groups, giving the three-dimensional framework. The crystal structure involves intra-anionic O-H⋯O hydrogen bonds and strong π-π stacking inter-actions [centroid-centroid distance = 3.6755 (7) Å]. PMID:21753973

  18. The kinetics and QSAR of abiotic reduction of mononitro aromatic compounds catalyzed by activated carbon.

    PubMed

    Gong, Wenwen; Liu, Xinhui; Gao, Ding; Yu, Yanjun; Fu, Wenjun; Cheng, Dengmiao; Cui, Baoshan; Bai, Junhong

    2015-01-01

    The kinetics of abiotic reduction of mono-nitro aromatic compounds (mono-NACs) catalyzed by activated carbon (AC) in an anaerobic system were examined. There were 6 types of substituent groups on nitrobenzene, including methyl, chlorine, amino, carboxyl, hydroxyl and cyanogen groups, at the ortho, meta or para positions. Our results showed that reduction followed pseudo-first order reaction kinetics, and that the rate constant (logkSA) varied widely, ranging between -4.77 and -2.82, depending upon the type and position of the substituent. A quantitative structure-activity relationship (QSAR) model using 15 theoretical molecular descriptors and partial-least-squares (PLS) regression was developed for the reduction rates of mono-NACs catalyzed by AC. The cross-validated regression coefficient (Qcum(2), 0.861) and correlation coefficient (R(2), 0.898) indicated significantly high robustness of the model. The VIP (variable importance in the projection) values of energy of the lowest unoccupied molecular orbital (ELUMO) and the maximum net atomic charge on the aromatic carbon bound to the nitro group (QC(-)) were 1.15 and 1.01, respectively. These values indicated that the molecular orbital energies and the atomic net charges might play important roles in the reduction of mono-NACs catalyzed by AC in anaerobic systems.

  19. Aromatic Cyanoalkylation through Double C-H Activation Mediated by Ni(III).

    PubMed

    Zhou, Wen; Zheng, Shuai; Schultz, Jason W; Rath, Nigam P; Mirica, Liviu M

    2016-05-11

    Herein we report an atom- and step-economic aromatic cyanoalkylation reaction that employs nitriles as building blocks and proceeds through Csp(2)-H and Csp(3)-H bond activation steps mediated by Ni(III). In addition to cyanomethylation with MeCN, regioselective α-cyanoalkylation was observed with various nitrile substrates to generate secondary and tertiary nitriles. Importantly, to the best of our knowledge these are the first examples of C-H bond activation reactions occurring at a Ni(III) center, which may exhibit different reactivity and selectivity profiles than those corresponding to analogous Ni(II) centers. These studies provide guiding principles to design catalytic C-H activation and functionalization reactions involving high-valent Ni species. PMID:27120207

  20. 3,3-Dinitro­azetidinium 2-hy­droxy­benzoate

    PubMed Central

    Gao, Rong; Yan, Biao; Mai, Tao; Hu, Ying; Guan, Yu-Lei

    2010-01-01

    In the title gem-dinitro­azetidinium 2-hy­droxy­benzoate salt, C3H6N3O4 +·C7H5O3 −, the azetidine ring is virtually planar, with a mean deviation from the plane of 0.0242 Å. The dihedral angle between the two nitro groups is 87.5 (1)°. PMID:21589190

  1. The structure and properties of 5,6-dinitro-1H-benzotriazole

    NASA Astrophysics Data System (ADS)

    Santa María, Dolores; Claramunt, Rosa M.; Torralba, M. Carmen; Torres, M. Rosario; Alkorta, Ibon; Elguero, José

    2016-06-01

    5,6-Dinitro-1H-benzotriazole crystallizes in the monoclinic system, space group P21/c. The asymmetric unit contains the planar 1H-tautomer together with a water molecule of crystallization. Each water molecule is hydrogen bonded to three adjacent 5,6-dinitrobenzotriazoles forming a tape along the b-axis of the crystal. These tapes stack along the c-axis through hydrogen bonds involving the water molecules and one of the nitro groups leading to a bidimensional structure. Solid-state 13C and 15N CPMAS NMR allow to confirm that the tautomer present is the 1H one. In DMSO-d6 solution the results are quite different and, based on GIAO/B3LYP/6-311++G(d,p) calculations, lead us to conclude that the major tautomer is the 5,6-dinitro-2H-benzotriazole, a surprising result that contradicts the rule that the major tautomer in solution coincides with the one present in the crystal. An anhydrous pseudopolymorph of 5,6-dinitro-1H-benzotriazole has been obtained as a non-crystalline form and from solid-state NMR and theoretical calculations, we conclude that it is an 1H-tautomer.

  2. Virucidal activity of essential oils from aromatic plants of San Luis, Argentina.

    PubMed

    García, C C; Talarico, L; Almeida, N; Colombres, S; Duschatzky, C; Damonte, E B

    2003-11-01

    Essential oils obtained from eight aromatic plants of San Luis Province, Argentina, were screened for virucidal activity against herpes simplex virus type 1 (HSV-1), Junin virus (JUNV) and dengue virus type 2 (DEN-2). The most potent inhibition was observed with the essential oil of Lippia junelliana and Lippia turbinata against JUNV with virucidal concentration 50% (VC(50)) values in the range 14-20 ppm, whereas Aloysia gratissima, Heterotheca latifolia and Tessaria absinthioides inhibited JUNV in the range 52-90 ppm. The virucidal activity was time- and temperature-dependent. The essential oils of A. gratissima, Artemisia douglasiana, Eupatorium patens and T. absinthioides inactivated HSV-1 at 65-125 ppm. However, only A. douglasiana and E. patens had any discernible effect on DEN-2 infectivity with VC(50) values of 60 and 150 ppm, respectively. PMID:14595590

  3. Double group transfer reactions: role of activation strain and aromaticity in reaction barriers.

    PubMed

    Fernández, Israel; Bickelhaupt, F Matthias; Cossío, Fernando P

    2009-12-01

    Double group transfer (DGT) reactions, such as the bimolecular automerization of ethane plus ethene, are known to have high reaction barriers despite the fact that their cyclic transition states have a pronounced in-plane aromatic character, as indicated by NMR spectroscopic parameters. To arrive at a way of understanding this somewhat paradoxical and incompletely understood phenomenon of high-energy aromatic transition states, we have explored six archetypal DGT reactions using density functional theory (DFT) at the OLYP/TZ2P level. The main trends in reactivity are rationalized using the activation strain model of chemical reactivity. In this model, the shape of the reaction profile DeltaE(zeta) and the height of the overall reaction barrier DeltaE( not equal)=DeltaE(zeta=zeta(TS)) is interpreted in terms of the strain energy DeltaE(strain)(zeta) associated with deforming the reactants along the reaction coordinate zeta plus the interaction energy DeltaE(int)(zeta) between these deformed reactants: DeltaE(zeta)=DeltaE(strain)(zeta)+DeltaE(int)(zeta). We also use an alternative fragmentation and a valence bond model for analyzing the character of the transition states. PMID:19852009

  4. Effect of different solvent on the photocatalytic activity of ZnIn2S4 for selective oxidation of aromatic alcohols to aromatic aldehydes under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Su, Li; Ye, Xiangju; Meng, Sugang; Fu, Xianliang; Chen, Shifu

    2016-10-01

    A series of ternary chalcogenides, zinc indium sulphide (ZnIn2S4), were synthesized by a simple solvothermal method with different solvents. The structure, textural, and optical properties of the resulting materials were thoroughly characterized by several techniques. The as-prepared ZnIn2S4 samples could all be employed as excellent photocatalysts to activate O2 for selective oxidation of aromatic alcohols to aromatic aldehydes under visible light illumination. The results showed that ZnIn2S4 prepared in ethanol solvent (ZIS-EtOH) exhibited the highest photocatalytic activity among the screened samples. The differences of photocatalytic performance for ZnIn2S4 samples prepared in different media were mainly attributed to the different levels of exposed {0001} special facets caused by the exposure extent of the basic crystal plane. In addition, rad O2- and positive holes were proved to be the main active species during the photocatalytic process. Combined with the previous reports, a possible photocatalytic mechanism for the selective oxidation of benzyl alcohol to benzaldehyde over ZnIn2S4 sample was proposed.

  5. Aromatic plants play an important role in promoting soil biological activity related to nitrogen cycling in an orchard ecosystem.

    PubMed

    Chen, Xinxin; Song, Beizhou; Yao, Yuncong; Wu, Hongying; Hu, Jinghui; Zhao, Lingling

    2014-02-15

    Aromatic plants can substantially improve the diversity and structure of arthropod communities, as well as reduce the number of herbivore pests and regulate the abundance of predators and parasitoids. However, it is not clear whether aromatic plants are also effective in improving soil quality by enhancing nutrient cycling. Here, field experiments are described involving intercropping with aromatic plants to investigate their effect on soil nitrogen (N) cycling in an orchard ecosystem. The results indicate that the soil organic nitrogen and available nitrogen contents increased significantly in soils intercropped with aromatic plants. Similarly, the activities of soil protease and urease increased, together with total microbial biomass involved in N cycling, including nitrifying bacteria, denitrifying bacteria and azotobacters, as well as the total numbers of bacteria and fungi. This suggests that aromatic plants improve soil N cycling and nutrient levels by enriching the soil in organic matter through the regulation of both the abundance and community structure of microorganisms, together with associated soil enzyme activity, in orchard ecosystems. PMID:24342101

  6. Aromatic plants play an important role in promoting soil biological activity related to nitrogen cycling in an orchard ecosystem.

    PubMed

    Chen, Xinxin; Song, Beizhou; Yao, Yuncong; Wu, Hongying; Hu, Jinghui; Zhao, Lingling

    2014-02-15

    Aromatic plants can substantially improve the diversity and structure of arthropod communities, as well as reduce the number of herbivore pests and regulate the abundance of predators and parasitoids. However, it is not clear whether aromatic plants are also effective in improving soil quality by enhancing nutrient cycling. Here, field experiments are described involving intercropping with aromatic plants to investigate their effect on soil nitrogen (N) cycling in an orchard ecosystem. The results indicate that the soil organic nitrogen and available nitrogen contents increased significantly in soils intercropped with aromatic plants. Similarly, the activities of soil protease and urease increased, together with total microbial biomass involved in N cycling, including nitrifying bacteria, denitrifying bacteria and azotobacters, as well as the total numbers of bacteria and fungi. This suggests that aromatic plants improve soil N cycling and nutrient levels by enriching the soil in organic matter through the regulation of both the abundance and community structure of microorganisms, together with associated soil enzyme activity, in orchard ecosystems.

  7. Depth heterogeneity of fully aromatic polyamide active layers in reverse osmosis and nanofiltration membranes.

    PubMed

    Coronell, Orlando; Mariñas, Benito J; Cahill, David G

    2011-05-15

    We studied the depth heterogeneity of fully aromatic polyamide (PA) active layers in commercial reverse osmosis (RO) and nanofiltration (NF) membranes by quantifying near-surface (i.e., top 6 nm) and volume-averaged properties of the active layers using X-ray photoelectron spectrometry (XPS) and Rutherford backscattering spectrometry (RBS), respectively. Some membranes (e.g., ESPA3 RO) had active layers that were depth homogeneous with respect to the concentration and pK(a) distribution of carboxylic groups, degree of polymer cross-linking, concentration of barium ion probe that associated with ionized carboxylic groups, and steric effects experienced by barium ion. Other membranes (e.g., NF90 NF) had active layers that were depth heterogeneous with respect to the same properties. Our results therefore support the existence of both depth-homogeneous and depth-heterogeneous active layers. It remains to be assessed whether the depth heterogeneity consists of gradually changing properties throughout the active layer depth or of distinct sublayers with different properties.

  8. New Quantitative Structure-Activity Relationship Models Improve Predictability of Ames Mutagenicity for Aromatic Azo Compounds.

    PubMed

    Manganelli, Serena; Benfenati, Emilio; Manganaro, Alberto; Kulkarni, Sunil; Barton-Maclaren, Tara S; Honma, Masamitsu

    2016-10-01

    Existing Quantitative Structure-Activity Relationship (QSAR) models have limited predictive capabilities for aromatic azo compounds. In this study, 2 new models were built to predict Ames mutagenicity of this class of compounds. The first one made use of descriptors based on simplified molecular input-line entry system (SMILES), calculated with the CORAL software. The second model was based on the k-nearest neighbors algorithm. The statistical quality of the predictions from single models was satisfactory. The performance further improved when the predictions from these models were combined. The prediction results from other QSAR models for mutagenicity were also evaluated. Most of the existing models were found to be good at finding toxic compounds but resulted in many false positive predictions. The 2 new models specific for this class of compounds avoid this problem thanks to a larger set of related compounds as training set and improved algorithms.

  9. [Assessment of exposure to cancerogenic aromatic hydrocarbon during controlled-access highways management activities].

    PubMed

    Martinotti, I; Cirla, A M; Cottica, D; Cirla, P E

    2011-01-01

    The purpose of this study was an integrated assessment of exposure to benzene and Polycyclic Aromatic Hydrocarbons (PAH) in 29 workers employed to manage a controlled-access highways. A campaign was performed in summertime by environmental monitoring (active and passive airborne personal sampler), as well as by biological monitoring (urine samples of the beginning and of the end of daily shift, baseline after two days of vacation). The measured environmental levels did not differ from background environmental concentrations found in a metropolitan area (i.e. benzo[a]pyrene < 1 ng/m3; benzene < 5 mcg/m3), and the results of biological monitoring were in agreement and were compatible with extra-professional habits of the investigated subjects (1-hydroxipyrene 50-990 ng/g creatinine; unmetabolized benzene 15-2010 ng/I; t-t muconic acid < 4-222 mcg/g creatinine).

  10. [Distribution, formation, carcinogenic and mutagenic activities of nitro derivatives of polycyclic aromatic hydrocarbons].

    PubMed

    Khesina, A Ia; Makhover, M S; Khitrovo, I A

    1989-01-01

    Nitro-PAHs (nitro-substituted derivatives of polycyclic aromatic hydrocarbons) are a class of chemical compounds with high biologic activity. They have been detected in samples of air pollutants, diesel and gasoline engine exhausts, in airplane exhaust emissions, cigarette smoke condensate, emissions of coke ovens, wood-burning fireplaces, coal-fired plants, in food and tea. Concentrations of nitro-PAHs have been compared with those of PAHs present in air pollutant samples and emissions from different sources. Information on the environmental occurrence, formation, and decomposition of nitro-PAHs in the atmosphere is given. Biologic effects (carcinogenic and mutagenic) of pure nitro-PAHs and nitro-PAHs-containing complex mixtures are discussed.

  11. New Quantitative Structure-Activity Relationship Models Improve Predictability of Ames Mutagenicity for Aromatic Azo Compounds.

    PubMed

    Manganelli, Serena; Benfenati, Emilio; Manganaro, Alberto; Kulkarni, Sunil; Barton-Maclaren, Tara S; Honma, Masamitsu

    2016-10-01

    Existing Quantitative Structure-Activity Relationship (QSAR) models have limited predictive capabilities for aromatic azo compounds. In this study, 2 new models were built to predict Ames mutagenicity of this class of compounds. The first one made use of descriptors based on simplified molecular input-line entry system (SMILES), calculated with the CORAL software. The second model was based on the k-nearest neighbors algorithm. The statistical quality of the predictions from single models was satisfactory. The performance further improved when the predictions from these models were combined. The prediction results from other QSAR models for mutagenicity were also evaluated. Most of the existing models were found to be good at finding toxic compounds but resulted in many false positive predictions. The 2 new models specific for this class of compounds avoid this problem thanks to a larger set of related compounds as training set and improved algorithms. PMID:27413112

  12. Antibacterial activities of essential oils from eight Greek aromatic plants against clinical isolates of Staphylococcus aureus.

    PubMed

    Alexopoulos, A; Kimbaris, A C; Plessas, S; Mantzourani, I; Theodoridou, I; Stavropoulou, E; Polissiou, M G; Bezirtzoglou, E

    2011-12-01

    Aromatic plants have been used widely to extend the shelf life of foods but at the same time research is undergoes for their properties as antibacterial agents in clinical use. Although there are promising results for the antimicrobial properties of various essential oils against environmental or food-isolated strains of Staphylococcus aureus, limited work has been done concerning these properties against clinical isolates of this pathogen. S. aureus is responsible for an increase number of nosocomial infections and at the same time exhibits increased resistance to synthetic agents. In this study, essential oils from eight aromatic plants common in Greece were isolated by hydrodistillation, analyzed by gas chromatography (GC) and GC/mass spectrometry (GC/MS) for their chemical components and tested for their antimicrobial activities against 24 clinical isolates of S. aureus. The methods used were disk diffusion and broth dilution in order to determine the Minimum Inhibitory Concentration (MIC). Our results showed that essential oils from Origanum vulgare and Origanum dictamnus were active against S. aureus when tested by disk diffusion, but exhibited increased MIC values (>256 mg/L) with the dilution method. In contrast, the reference strain NCTC 6571 showed to be extremely sensitive in most of the oils tested (MICs 0.25-32.0 mg/L) and resistant only to the essential oil from Ocimum basilicum. Therefore, there is no evidence of a potential clinical use for those essential oils and further research is needed in order to determine if they could substitute efficiently synthetic antibiotics or, perhaps be used in combination. PMID:21521657

  13. Chemical composition and antimicrobial activity of the essential oil from the edible aromatic plant Aristolochia delavayi.

    PubMed

    Li, Zhi-Jian; Njateng, Guy S S; He, Wen-Jia; Zhang, Hong-Xia; Gu, Jian-Long; Chen, Shan-Na; Du, Zhi-Zhi

    2013-11-01

    The essential oil obtained by hydrodistillation from the aerial parts of Aristolochia delavayi Franch. (Aristolochiaceae), a unique edible aromatic plant consumed by the Nakhi (Naxi) people in Yunnan, China, was investigated using GC/MS analysis. In total, 95 components, representing more than 95% of the oil composition, were identified, and the main constituents found were (E)-dec-2-enal (52.0%), (E)-dodec-2-enal (6.8%), dodecanal (3.35%), heptanal (2.88%), and decanal (2.63%). The essential oil showed strong inhibitory activity (96% reduction) of the production of bacterial volatile sulfide compounds (VSC) by Klebsiella pneumoniae, an effect that was comparable with that of the reference compound citral (91% reduction). Moreover, the antimicrobial activity of the essential oil and the isolated major compound against eight bacterial and six fungal strains were evaluated. The essential oil showed significant antibacterial activity against Providencia stuartii and Escherichia coli, with minimal inhibitory concentrations (MIC) ranging from 3.9 to 62.5 μg/ml. The oil also showed strong inhibitory activity against the fungal strains Trichophyton ajelloi, Trichophyton terrestre, Candida glabrata, Candida guilliermondii, and Cryptococcus neoformans, with MIC values ranging from 3.9 to 31.25 μg/ml, while (E)-dec-2-enal presented a lower antifungal activity than the essential oil. PMID:24243612

  14. Cytosolic activation of aromatic and heterocyclic amines. Inhibition by dicoumarol and enhancement in viral hepatitis B.

    PubMed Central

    De Flora, S; Bennicelli, C; D'Agostini, F; Izzotti, A; Camoirano, A

    1994-01-01

    The aromatic amines 2-aminofluorene (2AF), 2-acetylaminofluorene, and 2-aminoanthracene, and the heterocyclic amines 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline, and 3-amino-1-methyl-SH-pyrido[4,3-b]indole (Trp-P-2) were activated by rat liver cytosolic fractions to form mutagenic metabolites in Salmonella typhimurium strains TA98, TA98NR, and TA98/1,8-DNP6. In the case of the Trp-P-2, the cytosolic activation was even more potent than the microsomal activation, which is classically ascribed to N-hydroxylation and subsequent esterification. The cytosolic activation was a) NADPH-dependent, b) induced by pretreatment of rats with 3-methylcholanthrene and especially Aroclor 1254 but not by phenobarbital, and c) inhibited by dicoumarol. The hypothesis is that, following a preliminary oxidative step in the cytosol (pure cytosolic activation) or in microsomes via prostaglandin H synthase (mixed microsomal-cytosolic activation), an oxidized intermediate of amino compounds may serve as substrate for DT diaphorase activity and bielectronically reduced to the corresponding N-hydroxyamino derivative. Purified DT diaphorase, in the presence of either NADPH or NADH as electron donor, produced mutagenic derivatives from IQ and Trp-P-2. An NADPH-dependent activation of Trp-P-2 also occurred in the liver cytosol of woodchucks (Marmota monax), but was not inhibited by dicoumarol. As previously demonstrated with liver S-12 fractions in both humans and woodchucks, the cytosolic activation of Trp-P-2 was enhanced in animals affected by hepatitis B virus infection. This enhanced metabolism, which persisted even after appearance of primary hepatocellular carcinoma in virus carriers, is likely to be ascribed to mechanisms other than DT diaphorase induction, such as glutathione depletion. PMID:7534225

  15. Induction of mixed-function oxidase activity in mouse lymphoid tissues by polycyclic aromatic hydrocarbons

    SciTech Connect

    Griffin, G.D.; Egan, B.Z.; Lee, N.E.; Burtis, C.A.

    1986-01-01

    Polycyclic aromatic hydrocarbon (PAH) exposure can cause mixed-function oxidase (MFO) enzyme induction in certain tissues of various organisms. Measurements of such induction might serve as a useful bioindicator of human exposure to PAHs, provided readily obtainable human tissues can be utilized for such measurements. The authors have investigated the MFO activity in various lymphoid tissues of the C3H mouse as a model system and have studied the effect of systemic PAH treatment on such enzyme activity. An MFO enzyme assay was used to measure the activity of 7-ethoxyresorufin deethylase, an enzyme activity that may be specific for the cytochrome P-448 subset of MFO enzymes (those enzymes that are induced in cells or tissues following PAH administration). Intraperitoneal injection of mice with 180 mg/kg (4.6 mg) benzo(a)pyrene (BaP) or 160 mg/kg (4.0 mg) 3-methylcholanthrene (MC) produced a significant induction in MFO activity in mouse spleen S9 fractions 48 h after the injection. Induction ratios (induced activity/control activity) between 4 and 5 were seen with BaP; MC produced induction ratios of 2.5-3.0. Enzyme activity was not induced in the spleen within 16 h following BaP or MC administration. Other experiments indicated that MFO activity could be induced in thymus cells 48 h after either BaP or MC treatment. Treatment with BaP or MC did produce significant enzyme induction in the liver and lung tissues from the animals both 16 and 48 h after chemical treatment.

  16. Pilot study of aromatic hydrocarbon adsorption characteristics of disposable filtering facepiece respirators that contain activated carbon.

    PubMed

    Rozzi, Tony; Snyder, Jay; Novak, Debra

    2012-01-01

    Disposable filtering facepiece respirators (FFRs) used by health care workers are not designed to reduce the inhalation of volatile organic compounds (VOCs). Smoke-generating surgical procedures release VOCs and have been associated with the following complaints: foul smell, headaches, nausea, irritated throat and lungs, and asthma. Organic vapor FFRs that contain activated carbon are used by industrial workers to provide odor relief. These respirators remove irritating odors but are not marketed as respirators that provide respiratory protection against a gas or vapor. This study investigated the aromatic hydrocarbon adsorption capabilities of nuisance organic vapor (OV) FFRs. Three OV FFR models were tested to determine the 10% breakthrough time of three aromatic hydrocarbons at ambient room temperature and relative humidity. All respirator models were exposed to each vapor separately in three duplicate tests (n = 27). The respirator was sealed with silicone to an AVON-ISI headform that was placed in a chamber and exposed to VOC-laden air (20 ppm, 37 L/min). Periodically, gas samples were directed to an SRI gas chromatograph (Model 8610C) for analysis. All respirators performed similarly. The average 10% breakthrough values for all tests were at least 64 min, 96 min, and 110 min for benzene, toluene, and xylene, respectively. Respirators were tested with challenge concentrations at nuisance levels (20 ppm) and did not exceed 10% breakthrough values for at least 61 min. While the results of this pilot study hold promise, there is a need for further investigation and validation to determine the effectiveness of nuisance FFRs in mitigating organic vapors such as benzene, toluene, and xylene. PMID:22978813

  17. Antihyperlipidemic morpholine derivatives with antioxidant activity: An investigation of the aromatic substitution.

    PubMed

    Ladopoulou, Eleni M; Matralis, Alexios N; Nikitakis, Anastasios; Kourounakis, Angeliki P

    2015-11-01

    Drugs affecting more than one target could result in a more efficient treatment of multifactorial diseases as well as fewer safety concerns, compared to a one-drug one-target approach. Within our continued efforts towards the design of multifunctional molecules against atherosclerosis, we hereby report the synthesis of 17 new morpholine derivatives which structurally vary in terms of the aromatic substitution on the morpholine ring. These derivatives simultaneously suppress cholesterol biosynthesis through SQS inhibition (IC50 values of the most active compounds are between 0.7 and 5.5 μM) while exhibiting a significant protection of hepatic microsomal membranes against lipid peroxidation (with IC50 values for the most active compounds being between 73 and 200 μM). Further evaluation of these compounds was accomplished in vivo in an animal model of acute experimental hyperlipidemia, where it was observed that compounds reduced the examined lipidemic parameters (TC, TG and LDL) by 15-80%. In order to examine the mode of binding of these molecules in the active catalytic site of SQS, we also performed docking simulation studies. Our results indicate that some of the new compounds can be considered interesting structures in the search for new multifunctional agents of potential application in atherosclerosis.

  18. Production of the ammonium salt of 3,5-dinitro-1,2,4-triazole by solvent extraction

    DOEpatents

    Lee, Kien Y.; Ott, Donald G.

    1980-01-01

    The ammonium salt of 3,5-dinitro-1,2,4-triazole has utility as a chemical explosive. In accordance with the present invention, it may readily be produced by solvent extraction using high-molecular weight, water-insoluble amines followed by amination with anhydrous ammonia gas. The aqueous reaction mixture produced in the synthesis of the parent compound, 3,5-dinitro-1,2,4-triazole, is quite suitable--and indeed is preferred--for use as the feed material in the process of the invention.

  19. Production of the ammonium salt of 3,5-dinitro-1,2,4-triazole by solvent extraction

    DOEpatents

    Lee, K.Y.; Ott, D.G.

    1979-11-07

    The ammonium salt of 3,5-dinitro-1,2,4-triazole has utility as a chemical explosive. In accordance with the present invention, it may readily be produced by solvent extraction using high-molecular weight, water-insoluble amines, followed by amination with anhydrous ammonia gas. The aqueous reaction mixture produced in the synthesis of the parent compound, 3,5-dinitro-1,2,4-triazole, is quite suitable - and indeed is preferred - for use as the feed material in the process of the invention.

  20. Antimicrobial Activity of Seven Essential Oils From Iranian Aromatic Plants Against Common Causes of Oral Infections

    PubMed Central

    Zomorodian, Kamiar; Ghadiri, Pooria; Saharkhiz, Mohammad Jamal; Moein, Mohammad Reza; Mehriar, Peiman; Bahrani, Farideh; Golzar, Tahereh; Pakshir, Keyvan; Fani, Mohammad Mehdi

    2015-01-01

    Background: Over the past two decades, there has been a growing trend in using oral hygienic products originating from natural resources such as essential oils (EOs) and plant extracts. Seven aromatic plants used in this study are among popular traditional Iranian medicinal plants with potential application in modern medicine as anti-oral infectious diseases. Objectives: This study was conducted to determine the chemical composition and antimicrobial activities of essential oils from seven medicinal plants against pathogens causing oral infections. Materials and Methods: The chemical compositions of EOs distilled from seven plants were analyzed by gas chromatography/mass spectrometry (GC/MS). These plants included Satureja khuzestanica, S. bachtiarica, Ocimum sanctum, Artemisia sieberi, Zataria multiflora, Carum copticum and Oliveria decumbens. The antimicrobial activity of the essential oils was evaluated by broth micro-dilution in 96 well plates as recommended by the Clinical and Laboratory Standards Institute (CLSI) methods. Results: The tested EOs inhibited the growth of examined oral pathogens at concentrations of 0.015-16 µL/mL. Among the examined oral pathogens, Enterococcus faecalis had the highest Minimum Inhibitory Concentrations (MICs) and Minimum Microbicidal Concentrations (MMCs). Of the examined EOs, S. khuzestanica, Z. multiflora and S. bachtiarica, showed the highest antimicrobial activities, respectively, while Artemisia sieberi exhibited the lowest antimicrobial activity. Conclusions: The excellent antimicrobial activities of the tested EOs might be due to their major phenolic or alcoholic monoterpenes with known antimicrobial activities. Hence, these EOs can be possibly used as an antimicrobial agent in treatment and control of oral pathogens. PMID:25793100

  1. Enhancing muconic acid production from glucose and lignin-derived aromatic compounds via increased protocatechuate decarboxylase activity

    DOE PAGES

    Johnson, Christopher W.; Salvachua, Davinia; Khanna, Payal; Smith, Holly; Peterson, Darren J.; Beckham, Gregg T.

    2016-04-22

    The conversion of biomass-derived sugars and aromatic molecules to cis,cis-muconic acid (referred to hereafter as muconic acid or muconate) has been of recent interest owing to its facile conversion to adipic acid, an important commodity chemical. Metabolic routes to produce muconate from both sugars and many lignin-derived aromatic compounds require the use of a decarboxylase to convert protocatechuate (PCA, 3,4-dihydroxybenzoate) to catechol (1,2-dihydroxybenzene), two central aromatic intermediates in this pathway. Several studies have identified the PCA decarboxylase as a metabolic bottleneck, causing an accumulation of PCA that subsequently reduces muconate production. A recent study showed that activity of the PCAmore » decarboxylase is enhanced by co-expression of two genetically associated proteins, one of which likely produces a flavin-derived cofactor utilized by the decarboxylase. Using entirely genome-integrated gene expression, we have engineered Pseudomonas putida KT2440-derived strains to produce muconate from either aromatic molecules or sugars and demonstrate in both cases that co-expression of these decarboxylase associated proteins reduces PCA accumulation and enhances muconate production relative to strains expressing the PCA decarboxylase alone. In bioreactor experiments, co-expression increased the specific productivity (mg/g cells/h) of muconate from the aromatic lignin monomer p-coumarate by 50% and resulted in a titer of >15 g/L. In strains engineered to produce muconate from glucose, co-expression more than tripled the titer, yield, productivity, and specific productivity, with the best strain producing 4.92+/-0.48 g/L muconate. Furthermore, this study demonstrates that overcoming the PCA decarboxylase bottleneck can increase muconate yields from biomass-derived sugars and aromatic molecules in industrially relevant strains and cultivation conditions.« less

  2. Mycelia promote active transport and spatial dispersion of polycyclic aromatic hydrocarbons.

    PubMed

    Furuno, Shoko; Foss, Susan; Wild, Ed; Jones, Kevin C; Semple, Kirk T; Harms, Hauke; Wick, Lukas Y

    2012-05-15

    To cope with heterogeneous subsurface environments mycelial microorganisms have developed a unique ramified growth form. By extending hyphae, they can obtain nutrients from remote places and transport them even through air gaps and in small pore spaces, repectively. To date, studies have been focusing on the role that networks play in the distribution of nutrients. Here, we investigated the role of mycelia for the translocation of nonessential substances, using polycyclic aromatic hydrocarbons (PAHs) as model compounds. We show that the hyphae of the mycelial soil oomycete Pythium ultimum function as active translocation vectors for a wide range of PAHs. Visualization by two-photon excitation microscopy (TPEM) demonstrated the uptake and accumulation of phenanthrene (PHE) in lipid vesicles and its active transport by cytoplasmic streaming of the hyphae ('hyphal pipelines'). In mycelial networks, contaminants were translocated over larger distances than by diffusion. Given their transport capacity and ubiquity, hyphae may substantially distribute remote hydrophobic contaminants in soil, thereby improving their bioavailability to bacterial degradation. Hyphal contaminant dispersal may provide an untapped potential for future bioremediation approaches. PMID:22559873

  3. Autonomic nervous function and localization of cerebral activity during lavender aromatic immersion.

    PubMed

    Duan, Xudong; Tashiro, Manabu; Wu, Di; Yambe, Tomoyuki; Wang, Qingtian; Sasaki, Takehisa; Kumagai, Kazuaki; Luo, Yun; Nitta, Shin-ichi; Itoh, Masatoshi

    2007-01-01

    Changes in the autonomic nervous activity can be induced by various sensory and emotional stimuli. The authors examined whether the power spectral analysis of heart rate variability (HRV) could detect changes in autonomic tone following a lavender aroma treatment or not. Healthy young women (n=10, 23+/-3 years old) underwent continuous electrocardiographic (ECG) monitoring before and after (10, 20, 30 minutes) the lavender fragrance stimuli. HRV was expressed by three indices: low (0.04-0.15 Hz) and high (0.15-0.40 Hz) frequency components (nLF and nHF, respectively) as well as LF/HF ratio. Increases in the parasympathetic tone were observed after the lavender fragrance stimulus as seen as increases in the HF component and decreases in the LF/HF. Additional measurement with positron emission tomography (PET) demonstrated the regional metabolic activation in the orbitofrontal, posterior cingulate gyrus, brainstem, thalamus and cerebellum, as well as the reductions in the pre/post-central gyrus and frontal eye field. These results suggested that lavender aromatic treatment induced not only relaxation but also increased arousal level in these subjects. PMID:17361051

  4. Mosquito larvicidal activity of aromatic medicinal plant oils against Aedes aegypti and Culex pipiens pallens.

    PubMed

    Lee, Hoi-Seon

    2006-06-01

    Larvicidal activity of essential oils derived from 11 aromatic medicinal plants against early 4th-stage larvae of Aedes aegypti and Culex pipiens pallens was tested in the laboratory. At 100 ppm, the essential oils of all plants caused 100% mortality against Ae. aegypti and Cx. pipiens pallens. At 25 ppm, the essential oils of Citrus bergamia, Cuminum myrrha, and Pimenta racemosa caused 100% mortality against larvae of Ae. aegypti and Cx. pipiens pallens. The oil of C. begamia caused 32.5% and 24.5% mortality against Ae. aegypti and Cx. pipiens pallens at 12.5 ppm, but 24.2% and 0% mortality against Ae. aegypti and Cx. pipiens pallens at 6.25 ppm, respectively. The oil of P. racemosa caused 52.3% and 38.5% mortality against Ae. aegypti and Cx. pipiens pallens at 12.5 ppm, but 32.2% and 0% mortality against Ae. aegypti and Cx. pipiens pallens at 6.25 ppm, respectively. The larvicidal activity of oils of C. bergamia, C. myrrha, and P. racemosa was significantly reduced when used at 6.25 ppm. These plants warrant further studies as possible agents for mosquito control.

  5. Autonomic nervous function and localization of cerebral activity during lavender aromatic immersion.

    PubMed

    Duan, Xudong; Tashiro, Manabu; Wu, Di; Yambe, Tomoyuki; Wang, Qingtian; Sasaki, Takehisa; Kumagai, Kazuaki; Luo, Yun; Nitta, Shin-ichi; Itoh, Masatoshi

    2007-01-01

    Changes in the autonomic nervous activity can be induced by various sensory and emotional stimuli. The authors examined whether the power spectral analysis of heart rate variability (HRV) could detect changes in autonomic tone following a lavender aroma treatment or not. Healthy young women (n=10, 23+/-3 years old) underwent continuous electrocardiographic (ECG) monitoring before and after (10, 20, 30 minutes) the lavender fragrance stimuli. HRV was expressed by three indices: low (0.04-0.15 Hz) and high (0.15-0.40 Hz) frequency components (nLF and nHF, respectively) as well as LF/HF ratio. Increases in the parasympathetic tone were observed after the lavender fragrance stimulus as seen as increases in the HF component and decreases in the LF/HF. Additional measurement with positron emission tomography (PET) demonstrated the regional metabolic activation in the orbitofrontal, posterior cingulate gyrus, brainstem, thalamus and cerebellum, as well as the reductions in the pre/post-central gyrus and frontal eye field. These results suggested that lavender aromatic treatment induced not only relaxation but also increased arousal level in these subjects.

  6. Human aldo-keto reductases and the metabolic activation of polycyclic aromatic hydrocarbons.

    PubMed

    Penning, Trevor M

    2014-11-17

    Aldo-keto reductases (AKRs) are promiscuous NAD(P)(H) dependent oxidoreductases implicated in the metabolic activation of polycyclic aromatic hydrocarbons (PAH). These enzymes catalyze the oxidation of non-K-region trans-dihydrodiols to the corresponding o-quinones with the concomitant production of reactive oxygen species (ROS). The PAH o-quinones are Michael acceptors and can form adducts but are also redox-active and enter into futile redox cycles to amplify ROS formation. Evidence exists to support this metabolic pathway in humans. The human recombinant AKR1A1 and AKR1C1-AKR1C4 enzymes all catalyze the oxidation of PAH trans-dihydrodiols to PAH o-quinones. Many human AKRs also catalyze the NADPH-dependent reduction of the o-quinone products to air-sensitive catechols, exacerbating ROS formation. Moreover, this pathway of PAH activation occurs in a panel of human lung cell lines, resulting in the production of ROS and oxidative DNA damage in the form of 8-oxo-2'-deoxyguanosine. Using stable-isotope dilution liquid chromatography tandem mass spectrometry, this pathway of benzo[a]pyrene (B[a]P) metabolism was found to contribute equally with the diol-epoxide pathway to the activation of this human carcinogen in human lung cells. Evaluation of the mutagenicity of anti-B[a]P-diol epoxide with B[a]P-7,8-dione on p53 showed that the o-quinone produced by AKRs was the more potent mutagen, provided that it was permitted to redox cycle, and that the mutations observed were G to T transversions, reminiscent of those observed in human lung cancer. It is concluded that there is sufficient evidence to support the role of human AKRs in the metabolic activation of PAH in human lung cell lines and that they may contribute to the causation of human lung cancer.

  7. Human Aldo-Keto Reductases and the Metabolic Activation of Polycyclic Aromatic Hydrocarbons

    PubMed Central

    2015-01-01

    Aldo-keto reductases (AKRs) are promiscuous NAD(P)(H) dependent oxidoreductases implicated in the metabolic activation of polycyclic aromatic hydrocarbons (PAH). These enzymes catalyze the oxidation of non-K-region trans-dihydrodiols to the corresponding o-quinones with the concomitant production of reactive oxygen species (ROS). The PAH o-quinones are Michael acceptors and can form adducts but are also redox-active and enter into futile redox cycles to amplify ROS formation. Evidence exists to support this metabolic pathway in humans. The human recombinant AKR1A1 and AKR1C1–AKR1C4 enzymes all catalyze the oxidation of PAH trans-dihydrodiols to PAH o-quinones. Many human AKRs also catalyze the NADPH-dependent reduction of the o-quinone products to air-sensitive catechols, exacerbating ROS formation. Moreover, this pathway of PAH activation occurs in a panel of human lung cell lines, resulting in the production of ROS and oxidative DNA damage in the form of 8-oxo-2′-deoxyguanosine. Using stable-isotope dilution liquid chromatography tandem mass spectrometry, this pathway of benzo[a]pyrene (B[a]P) metabolism was found to contribute equally with the diol-epoxide pathway to the activation of this human carcinogen in human lung cells. Evaluation of the mutagenicity of anti-B[a]P-diol epoxide with B[a]P-7,8-dione on p53 showed that the o-quinone produced by AKRs was the more potent mutagen, provided that it was permitted to redox cycle, and that the mutations observed were G to T transversions, reminiscent of those observed in human lung cancer. It is concluded that there is sufficient evidence to support the role of human AKRs in the metabolic activation of PAH in human lung cell lines and that they may contribute to the causation of human lung cancer. PMID:25279998

  8. Synthesis of 4,10-Dinitro-2,6,8,12-tetraoxa-4,10-diazaisowurtzitane (TEX) Using Heteropolyacids as Efficient and Recyclable Heterogeneous Catalysts

    NASA Astrophysics Data System (ADS)

    Bayat, Yadollah; Azizkhani, Vahid

    2012-07-01

    4,10-Dinitro-2,6,8,12-tetraoxa-4,10-diazaisowurtzitane (TEX) is well known as an efficient explosive compound. It is usually prepared via nitration of a precursor with a mixture of concentrated nitric and sulfuric acid. However, there are many difficulties with the use of old methods, such as strong acidic and thermal conditions, which cause product decomposition, low yields, hazardous wastes, and product separation difficulties. In this article, the use of an efficient catalytic and mild reaction conditions for TEX synthesis is reported for the first time. It has been well documented that heteropolyacids (HPAs) are efficient green catalysts for use as a nitric acid activator. This strategy provided milder and higher yield conditions for nitration reactions. In addition, the reactions can be reasonably run at lower temperatures in a short time.

  9. Warm dust and aromatic bands as quantitative probes of star-formation activity

    NASA Astrophysics Data System (ADS)

    Förster Schreiber, N. M.; Roussel, H.; Sauvage, M.; Charmandaris, V.

    2004-05-01

    We combine samples of spiral galaxies and starburst systems observed with ISOCAM on board ISO to investigate the reliability of mid-infrared dust emission as a quantitative tracer of star formation activity. The total sample covers very diverse galactic environments and probes a much wider dynamic range in star formation rate density than previous similar studies. We find that both the monochromatic 15 μm continuum and the 5-8.5 μm emission constitute excellent indicators of the star formation rate as quantified by the Lyman continuum luminosity LLyc, within specified validity limits which are different for the two tracers. Normalized to projected surface area, the 15 μm continuum luminosity Σ15 μm,ct is directly proportional to ΣLyc over several orders of magnitude. Two regimes are distinguished from the relative offsets in the observed relationship: the proportionality factor increases by a factor of ≈5 between quiescent disks in spiral galaxies, and moderate to extreme star-forming environments in circumnuclear regions of spirals and in starburst systems. The transition occurs near ΣLyc ˜ 102 L⊙ pc-2 and is interpreted as due to very small dust grains starting to dominate the emission at 15 μm over aromatic species above this threshold. The 5-8.5 μm luminosity per unit projected area is also directly proportional to the Lyman continuum luminosity, with a single conversion factor from the most quiescent objects included in the sample up to ΣLyc ˜ 104 L⊙ pc-2, where the relationship then flattens. The turnover is attributed to depletion of aromatic band carriers in the harsher conditions prevailing in extreme starburst environments. The observed relationships provide empirical calibrations useful for estimating star formation rates from mid-infrared observations, much less affected by extinction than optical and near-infrared tracers in deeply embedded H II regions and obscured starbursts, as well as for theoretical predictions from evolutionary

  10. Genetic engineering activates biosynthesis of aromatic fumaric acid amides in the human pathogen Aspergillus fumigatus.

    PubMed

    Kalb, Daniel; Heinekamp, Thorsten; Lackner, Gerald; Scharf, Daniel H; Dahse, Hans-Martin; Brakhage, Axel A; Hoffmeister, Dirk

    2015-03-01

    The Aspergillus fumigatus nonribosomal peptide synthetase FtpA is among the few of this species whose natural product has remained unknown. Both FtpA adenylation domains were characterized in vitro. Fumaric acid was identified as preferred substrate of the first and both l-tyrosine and l-phenylalanine as preferred substrates of the second adenylation domain. Genetically engineered A. fumigatus strains expressed either ftpA or the regulator gene ftpR, encoded in the same cluster of genes, under the control of the doxycycline-inducible tetracycline-induced transcriptional activation (tet-on) cassette. These strains produced fumaryl-l-tyrosine and fumaryl-l-phenylalanine which were identified by liquid chromatography and high-resolution mass spectrometry. Modeling of the first adenylation domain in silico provided insight into the structural requirements to bind fumaric acid as peptide synthetase substrate. This work adds aromatic fumaric acid amides to the secondary metabolome of the important human pathogen A. fumigatus which was previously not known as a producer of these compounds.

  11. Mineralisation and primary biodegradation of aromatic organophosphorus flame retardants in activated sludge.

    PubMed

    Jurgens, Sharona S; Helmus, Rick; Waaijers, Susanne L; Uittenbogaard, Dirk; Dunnebier, Dorien; Vleugel, Melissa; Kraak, Michiel H S; de Voogt, Pim; Parsons, John R

    2014-09-01

    Halogen-free flame retardants (HFFRs), such as the aromatic organophosphorus flame retardants (OPFRs) triphenyl phosphate (TPHP), resorcinol bis(diphenylphosphate) (PBDPP) and bisphenol A bis(diphenylphosphate) (BPA-BDPP) have been proposed as potential replacements for brominated flame retardants in polymers and textiles. Although these OPFRs are already marketed, their environmental fate and effects are poorly characterised. The aim of this study was therefore to determine the mineralisation and primary biodegradation of these OPFRs by activated sludge. Mineralisation was monitored by measuring CO2 production by means of GC analysis, whereas primary biodegradation was monitored by LC-MS/MS analysis of the OPFRs and their potential metabolites. TPHP was biodegraded and mineralised most rapidly and achieved the requirement for ready biodegradability (60% of theoretical maximum mineralisation). Primary biodegradation was also rapid for PBDPP, but 60% mineralisation was not achieved within the time of the test, suggesting that transformation products of PBDPP may accumulate. Primary degradation of BPA-BDPP was very slow and very low CO2 production was also observed. Based on these results, TPHP and to a lesser extent PBDPP appear to be suitable replacements for the more environmentally persistent brominated flame retardants. PMID:24997924

  12. Genetic Engineering Activates Biosynthesis of Aromatic Fumaric Acid Amides in the Human Pathogen Aspergillus fumigatus

    PubMed Central

    Kalb, Daniel; Heinekamp, Thorsten; Lackner, Gerald; Scharf, Daniel H.; Dahse, Hans-Martin; Brakhage, Axel A.

    2014-01-01

    The Aspergillus fumigatus nonribosomal peptide synthetase FtpA is among the few of this species whose natural product has remained unknown. Both FtpA adenylation domains were characterized in vitro. Fumaric acid was identified as preferred substrate of the first and both l-tyrosine and l-phenylalanine as preferred substrates of the second adenylation domain. Genetically engineered A. fumigatus strains expressed either ftpA or the regulator gene ftpR, encoded in the same cluster of genes, under the control of the doxycycline-inducible tetracycline-induced transcriptional activation (tet-on) cassette. These strains produced fumaryl-l-tyrosine and fumaryl-l-phenylalanine which were identified by liquid chromatography and high-resolution mass spectrometry. Modeling of the first adenylation domain in silico provided insight into the structural requirements to bind fumaric acid as peptide synthetase substrate. This work adds aromatic fumaric acid amides to the secondary metabolome of the important human pathogen A. fumigatus which was previously not known as a producer of these compounds. PMID:25527545

  13. Aerobic metabolism and cardiac activity in the descendants of zebrafish exposed to pyrolytic polycyclic aromatic hydrocarbons.

    PubMed

    Lucas, Julie; Perrichon, Prescilla; Nouhaud, Marine; Audras, Alexandre; Leguen, Isabelle; Lefrancois, Christel

    2014-12-01

    The increase of anthropogenic activities on coastal areas induces discharges of polycyclic aromatic hydrocarbons (PAHs) in aquatic ecosystem. PAH effects depend not only on their concentration and the way of contamination but also on the different developmental stages of the organism. Zebrafish were exposed to relevant concentration of pyrolytic PAHs from the first meal (i.e., 5-day post fertilization, dpf) to mature adults. Parental effect of this type of exposure was evaluated through the assessment of aerobic metabolic scope, cardiac frequency, and cardiac mRNA expression on larval and/or embryo progeny of contaminated fish. Our results suggest that cardiac frequency increased in larval descendants of fish exposed to the environmental concentration of pyrolytic PAHs (i.e., 5 ng.g(-1) of food), while a lack of effect on aerobic metabolism in 5 dpf larvae was highlighted. A surexpression of mRNA related to the cardiac calcium transporting ATPase atp2a2a, a protein essential for contraction, is in accordance with this increasing cardiac frequency. Even if cardiac development genes cmlc1 and tnnt2a were not affected at early life stages tested, complementary work on cardiac structure could be interesting to better understand PAHs action.

  14. Targeting of Arenavirus RNA Synthesis by a Carboxamide-Derivatized Aromatic Disulfide with Virucidal Activity

    PubMed Central

    Sepúlveda, Claudia S.; García, Cybele C.; Levingston Macleod, Jesica M.

    2013-01-01

    Several arenaviruses can cause severe hemorrhagic fever (HF) in humans, representing a public health threat in endemic areas of Africa and South America. The present study characterizes the potent virucidal activity of the carboxamide-derivatized aromatic disulfide NSC4492, an antiretroviral zinc finger-reactive compound, against Junín virus (JUNV), the causative agent of Argentine HF. The compound was able to inactivate JUNV in a time and temperature-dependent manner, producing more than 99 % reduction in virus titer upon incubation with virions at 37°C for 90 min. The ability of NSC4492-treated JUNV to go through different steps of the multiplication cycle was then evaluated. Inactivated virions were able to bind and enter into the host cell with similar efficiency as control infectious particles. In contrast, treatment with NSC4492 impaired the capacity of JUNV to drive viral RNA synthesis, as measured by quantitative RT-PCR, and blocked viral protein expression, as determined by indirect immunofluorescence. These results suggest that the disulfide NSC4492 targets on the arenavirus replication complex leading to impairment in viral RNA synthesis. Additionally, analysis of VLP produced in NSC4492-treated cells expressing JUNV matrix Z protein revealed that the compound may interact with Z resulting in an altered aggregation behavior of this protein, but without affecting its intrinsic self-budding properties. The potential perspectives of NSC4492 as an inactivating vaccinal compound for pathogenic arenaviruses are discussed. PMID:24278404

  15. Identification of acidic and aromatic residues in the Zta activation domain essential for Epstein-Barr virus reactivation.

    PubMed

    Deng, Z; Chen, C J; Zerby, D; Delecluse, H J; Lieberman, P M

    2001-11-01

    Epstein-Barr virus (EBV) lytic cycle transcription and DNA replication require the transcriptional activation function of the viral immediate-early protein Zta. We describe a series of alanine substitution mutations in the Zta activation domain that reveal two functional motifs based on amino acid composition. Alanine substitution of single or paired hydrophobic aromatic amino acid residues resulted in modest transcription activation defects, while combining four substitutions of aromatic residues (F22/F26/W74/F75) led to more severe transcription defects. Substitution of acidic amino acid residue E27, D35, or E54 caused severe transcription defects on most viral promoters. Promoter- and cell-specific defects were observed for some substitution mutants. Aromatic residues were required for Zta interaction with TFIIA-TFIID and the CREB-binding protein (CBP) and for stimulation of CBP histone acetyltransferase activity in vitro. In contrast, acidic amino acid substitution mutants interacted with TFIIA-TFIID and CBP indistinguishably from the wild type. The nuclear domain 10 (ND10) protein SP100 was dispersed by most Zta mutants, but acidic residue mutations led to reduced, while aromatic substitution mutants led to increased SP100 nuclear staining. Acidic residue substitution mutants had more pronounced defects in transcription activation of endogenous viral genes in latently infected cells and for viral replication, as measured by the production of infectious virus. One mutant, K12/F13, was incapable of stimulating EBV lytic replication but had only modest transcription defects. These results indicate that Zta stimulates viral reactivation through two nonredundant structural motifs, one of which interacts with general transcription factors and coactivators, and the other has an essential but as yet not understood function in lytic transcription.

  16. Thiolates Chemically Induce Redox Activation of BTZ043 and Related Potent Nitro Aromatic Anti-Tuberculosis Agents

    PubMed Central

    Tiwari, Rohit; Moraski, Garrett C.; Krchňák, Viktor; Miller, Patricia A.; Colon-Martinez, Mariangelli; Herrero, Eliza; Oliver, Allen G.; Miller, Marvin J.

    2013-01-01

    The development of multidrug resistant (MDR) and extensively drug resistant (XDR) forms of tuberculosis (TB) has stimulated research efforts globally to expand the new drug pipeline. Nitro aromatic compounds, including 1, 3-Benzothiazin-4-ones (BTZs) and related agents, are a promising new class for the treatment of TB. Research has shown that the nitroso intermediates of BTZs that are generated in vivo cause suicide inhibition of decaprenylphosphoryl-β-D-ribose 2′ oxidase (DprE1), which is responsible for cell wall arabinogalactan biosynthesis. We have designed and synthesized novel anti-TB agents inspired from BTZs and other nitroaromatic compounds. Computational studies indicated that the unsubstituted aromatic carbons of BTZ043 and related nitroaromatic compounds are the most electron deficient and might be prone to nucleophilic attack. Our chemical studies on BTZ043 and the additional nitro aromatic compounds synthesized by us and the others confirmed the postulated reactivity. The results indicate that nucleophiles such as thiolates, cyanide and hydride induce non-enzymatic reduction of the nitro groups present in these compounds to the corresponding nitroso intermediates by addition at the unsubstituted electron deficient aromatic carbon present in these compounds. Furthermore we demonstrate here that these compounds are good candidates for the classical von Richter reaction. These chemical studies offer an alternate hypotheses for the mechanism of action of nitro aromatic anti-TB agents in that the cysteine thiol(ate) or a hydride source at the active site of DprE1 may trigger the reduction of the nitro groups in a manner similar to the von Richter reaction to the nitroso intermediates, to initiate the inhibition of DprE1. PMID:23402278

  17. Heterolytic Activation of Hydrogen Promoted by Ruthenium Nanoparticles immobilized on Basic Supports and Hydrogenation of Aromatic Compounds

    NASA Astrophysics Data System (ADS)

    Fang, Minfeng

    Despite the aggressive development and deployment of new renewable and nuclear technologies, petroleum-derived transportation fuels---gasoline, diesel and jet fuels---will continue to dominate the markets for decades. Environmental legislation imposes severe limits on the tolerable proportion of aromatics, sulfur and nitrogen contents in transportation fuels, which is difficult to achieve with current refining technologies. Catalytic hydrogenation plays an important role in the production of cleaner fuels, both as a direct means to reduce the aromatics and as a key step in the hydrodenitrogenation (HDN) and hydrodesulfurization (HDS) processes. However, conventional catalysts require drastic conditions and/or are easily poisoned by S or N aromatics. Therefore, there is still a need for new efficient catalysts for hydrogenation reactions relevant to the production of cleaner fossil fuels. Our catalyst design involves metallic nanoparticles intimately associated with a basic support, with the aim of creating a nanostructure capable of promoting the heterolytic activation of hydrogen and ionic hydrogenation mechanisms, as a strategy to avoid catalyst poisoning and enhance catalytic activity. We have designed and prepared a new nanostructured catalytic material composed of RuNPs immobilized on the basic polymer P4VPy. We have demonstrated that the Ru/P4VPy catalyst can promote heterolytic hydrogen activation and a unique surface ionic hydrogenation mechanism for the efficient hydrogenation of N-aromatics. This is the first time these ionic hydrogenation pathways have been demonstrated on solid surfaces. For the RuNPs surfaces without basic sites in close proximity, the conventional homolytic H2 splitting is otherwise involved. Using the mechanistic concepts from Ru/P4VPy, we have designed and prepared the Ru/MgO catalyst, with the aim to improve the catalytic efficiency for the hydrogenation of heteroatom aromatics operating by the ionic hydrogenation mechanism. The Ru

  18. Activation of the cnidarian oxidative stress response by ultraviolet radiation, polycyclic aromatic hydrocarbons and crude oil

    PubMed Central

    Tarrant, A. M.; Reitzel, A. M.; Kwok, C. K.; Jenny, M. J.

    2014-01-01

    Organisms are continuously exposed to reactive chemicals capable of causing oxidative stress and cellular damage. Antioxidant enzymes, such as superoxide dismutases (SODs) and catalases, are present in both prokaryotes and eukaryotes and provide an important means of neutralizing such oxidants. Studies in cnidarians have previously documented the occurrence of antioxidant enzymes (transcript expression, protein expression and/or enzymatic activity), but most of these studies have not been conducted in species with sequenced genomes or included phylogenetic analyses, making it difficult to compare results across species due to uncertainties in the relationships between genes. Through searches of the genome of the sea anemone Nematostella vectensis Stephenson, one catalase gene and six SOD family members were identified, including three copper/zinc-containing SODs (CuZnSODs), two manganese-containing SODs (MnSODs) and one copper chaperone of SOD (CCS). In 24 h acute toxicity tests, juvenile N. vectensis showed enhanced sensitivity to combinations of ultraviolet radiation (UV) and polycyclic aromatic hydrocarbons (PAHs, specifically pyrene, benzo[a]pyrene and fluoranthene) relative to either stressor alone. Adult N. vectensis exhibited little or no mortality following UV, benzo[a]pyrene or crude oil exposure but exhibited changes in gene expression. Antioxidant enzyme transcripts were both upregulated and downregulated following UV and/or chemical exposure. Expression patterns were most strongly affected by UV exposure but varied between experiments, suggesting that responses vary according to the intensity and duration of exposure. These experiments provide a basis for comparison with other cnidarian taxa and for further studies of the oxidative stress response in N. vectensis. PMID:24436378

  19. Aromatic plants essential oils activity on Fusarium verticillioides Fumonisin B(1) production in corn grain.

    PubMed

    López, A G; Theumer, M G; Zygadlo, J A; Rubinstein, H R

    2004-10-01

    The minimum inhibitory concentration (MIC) of Origanum vulgare, Aloysia triphylla, Aloysia polystachya and Mentha piperita essential oils (EOs) against Fusarium verticillioides M 7075 (F. moniliforme, Sheldon) were assessed, using the semisolid agar antifungal susceptibility (SAAS) technique. O. vulgare, A. triphylla, A. polystachya and M. piperita EOs were evaluated at final concentrations of 10, 20, 40, 50, 100, 200, 250, 500, 1000 and 1500 epsilonl per litre (epsilonl/l) of culture medium. A. triphylla and O. vulgare EOs showed the highest inhibitory effects on F. verticillioides mycelial development. This inhibition was observed at 250 and 500 epsilonl/l for EOs coming from Aloysia triphylla and O. vulgare, respectively. Thus, the effects of EOs on FB(1) production were evaluated using corn grain (Zea mays) as substrate. The EOs were inserted on the 5th, 10th, 15th and 20th day of maize postinoculation with a conidia suspension of F. verticillioides. O. vulgare and A. triphylla were applied to give final concentrations of 30 ppm and 45 ppm, respectively. Different effects were observed in the toxicogenicity at the 20th day treatment. The O. vulgare EO decreased the production level of FB(1) (P < 0.01) while A. triphyla EO increased it (P < 0.001) with respect to those obtained in the inoculated maize, not EOs treated. Results obtained in the present work indicate that fumonisin production could be inhibited or stimulated by some constituents of EOs coming from aromatic plants. Further studies should be performed to identify the components of EOs with modulatory activity on the growth and fumonisins production of Fusarium verticillioides.

  20. Aromatic plants essential oils activity on Fusarium verticillioides Fumonisin B(1) production in corn grain.

    PubMed

    López, A G; Theumer, M G; Zygadlo, J A; Rubinstein, H R

    2004-10-01

    The minimum inhibitory concentration (MIC) of Origanum vulgare, Aloysia triphylla, Aloysia polystachya and Mentha piperita essential oils (EOs) against Fusarium verticillioides M 7075 (F. moniliforme, Sheldon) were assessed, using the semisolid agar antifungal susceptibility (SAAS) technique. O. vulgare, A. triphylla, A. polystachya and M. piperita EOs were evaluated at final concentrations of 10, 20, 40, 50, 100, 200, 250, 500, 1000 and 1500 epsilonl per litre (epsilonl/l) of culture medium. A. triphylla and O. vulgare EOs showed the highest inhibitory effects on F. verticillioides mycelial development. This inhibition was observed at 250 and 500 epsilonl/l for EOs coming from Aloysia triphylla and O. vulgare, respectively. Thus, the effects of EOs on FB(1) production were evaluated using corn grain (Zea mays) as substrate. The EOs were inserted on the 5th, 10th, 15th and 20th day of maize postinoculation with a conidia suspension of F. verticillioides. O. vulgare and A. triphylla were applied to give final concentrations of 30 ppm and 45 ppm, respectively. Different effects were observed in the toxicogenicity at the 20th day treatment. The O. vulgare EO decreased the production level of FB(1) (P < 0.01) while A. triphyla EO increased it (P < 0.001) with respect to those obtained in the inoculated maize, not EOs treated. Results obtained in the present work indicate that fumonisin production could be inhibited or stimulated by some constituents of EOs coming from aromatic plants. Further studies should be performed to identify the components of EOs with modulatory activity on the growth and fumonisins production of Fusarium verticillioides. PMID:15702272

  1. Adsorption of aromatic organic acids onto high area activated carbon cloth in relation to wastewater purification.

    PubMed

    Ayranci, Erol; Duman, Osman

    2006-08-25

    Adsorption of aromatic organic acids: benzoic acid (BA), salicylic acid (SA), p-aminobenzoic acid (pABA) and nicotinic acid (NA), onto high area activated carbon cloth from solutions in 0.4 M H(2)SO(4), in water at natural pH, in 0.1 M NaOH and also from solutions having pH 7.0 were studied by in situ UV-spectroscopic technique. The first-order rate law was found to be applicable for the kinetic data of adsorption. The rates and extents of adsorption of the organic acids were the highest from water or 0.4 M H(2)SO(4) solutions and the lowest from 0.1 M NaOH solution. The order of rates and extents of adsorption of the four organic acids in each of the four solutions (0.4 M H(2)SO(4), water, solution of pH 7.0 and 0.1 M NaOH) was determined as SA>BA>NA approximately pABA. These observed orders were explained in terms of electrostatic, dispersion and hydrogen bonding interactions between the surface and the adsorbate species, taking the charge of the carbon surface and the adsorbate in each solution into account. Adsorption of BA in molecular form or in benzoate form was analyzed by treating the solution as a mixture of two components and applying Lambert-Beer law to two-component system. The adsorption isotherm data of the systems studied were derived at 30 degrees C and fitted to Langmuir and Freundlich equations. PMID:16442224

  2. GC-MS-olfactometric characterization of the most aroma-active components in a representative aromatic extract from Iranian saffron (Crocus sativus L.).

    PubMed

    Amanpour, Asghar; Sonmezdag, A Salih; Kelebek, Hasim; Selli, Serkan

    2015-09-01

    Aroma and aroma-active compounds of Iranian saffron (Crocus sativus L.) were analyzed by gas chromatography-mass spectrometry-olfactometry. The saffron aromatic extracts were obtained by four different extraction techniques including solvent-assisted flavour evaporation (SAFE), liquid-liquid extraction (LLE), solid phase extraction (SPE), and simultaneous distillation extraction (SDE) and compared to achieve a representative aromatic extract from saffron. According to sensory analysis, the aromatic extract obtained by SAFE was the most representative of saffron odour. A total of 28 aroma compounds were identified in saffron. Ketones were quantitatively the most dominant volatiles in saffron, followed by aldehydes and acids. Aroma extract dilution analysis (AEDA) was used for the determination of aroma-active compounds of saffron. A total of nine aroma-active compounds were detected in the aromatic extract. On the basis of the flavour dilution (FD) factor, the most powerful aroma active compounds were safranal (FD = 512), 4-ketoisophorone (FD = 256) and dihydrooxophorone (FD = 128).

  3. The doping effect of fluorinated aromatic hydrocarbon solvents on the performance of common olefin metathesis catalysts: application in the preparation of biologically active compounds.

    PubMed

    Samojłowicz, Cezary; Bieniek, Michał; Zarecki, Andrzej; Kadyrov, Renat; Grela, Karol

    2008-12-21

    Aromatic fluorinated hydrocarbons, used as solvents for olefin metathesis reactions, catalysed by standard commercially available Ru precatalysts, allow substantially higher yields to be obtained, especially of challenging substrates, including natural and biologically active compounds.

  4. Synthesis of high specific activity (+)- and (-)-6-( sup 18 F)fluoronorepinephrine via the nucleophilic aromatic substitution reaction

    SciTech Connect

    Ding, Y.S.; Fowler, J.S.; Gatley, S.J.; Dewey, S.L.; Wolf, A.P. )

    1991-02-01

    The first example of a no-carrier-added {sup 18}F-labeled catecholamine, 6-({sup 18}F)fluoronorepinephrine (6-({sup 18}F)FNE), has been synthesized via nucleophilic aromatic substitution. The racemic mixture was resolved on a chiral HPLC column to obtain pure samples of (-)-6-({sup 18}F)FNE and (+)6-({sup 18}F)FNE. Radiochemical yields of 20% at the end of bombardment (EOB) for the racemic mixture (synthesis time 93 min), 6% for each enantiomer (synthesis time 128 min) with a specific activity of 2-5 Ci/mumol at EOB were obtained. Chiral HPLC peak assignment for the resolved enantiomers was achieved by using two independent methods: polarimetric determination and reaction with dopamine beta-hydroxylase. Positron emission tomography (PET) studies with racemic 6-({sup 18}F)FNE show high uptake and retention in the baboon heart. This work demonstrates that nucleophilic aromatic substitution by ({sup 18}F)fluoride ion is applicable to systems having electron-rich aromatic rings, leading to high specific activity radiopharmaceuticals. Furthermore, the suitably protected dihydroxynitrobenzaldehyde 1 may serve as a useful synthetic precursor for the radiosynthesis of other complex {sup 18}F-labeled radiotracers.

  5. Haemolytic activity of aromatic heptaenes. A group of polyene macrolide antifungal antibiotics.

    PubMed

    Cybulska, B; Mazerski, J; Borowski, E; Gary-Bobo, C M

    1984-01-01

    The aromatic heptaene vacidin A induces ion selective channels in human red blood cells. The ion flux induced leads to a secondary effect--colloid osmotic haemolysis. Molecular variations at ionizable polar groups of the antibiotic modify the properties of the permeability pathway concerning intercationic selectivity and the symmetry of ion flux. PMID:6704143

  6. Nucleophilic Aromatic Substitution.

    ERIC Educational Resources Information Center

    Avila, Walter B.; And Others

    1990-01-01

    Described is a microscale organic chemistry experiment which demonstrates one feasible route in preparing ortho-substituted benzoic acids and provides an example of nucleophilic aromatic substitution chemistry. Experimental procedures and instructor notes for this activity are provided. (CW)

  7. C2-substituted aromatic cytokinin sugar conjugates delay the onset of senescence by maintaining the activity of the photosynthetic apparatus.

    PubMed

    Vylíčilová, Hana; Husičková, Alexandra; Spíchal, Lukáš; Srovnal, Josef; Doležal, Karel; Plíhal, Ondřej; Plíhalová, Lucie

    2016-02-01

    Cytokinins are plant hormones with biological functions ranging from coordination of plant growth and development to the regulation of senescence. A series of 2-chloro-N(6)-(halogenobenzylamino)purine ribosides was prepared and tested for cytokinin activity in detached wheat leaf senescence, tobacco callus and Amaranthus bioassays. The synthetic compounds showed significant activity, especially in delaying senescence in detached wheat leaves. They were also tested in bacterial receptor bioassays using both monocot and dicot members of the cytokinin receptor family. Most of the derivatives did not trigger cytokinin signaling via the AHK3 and AHK4 receptors from Arabidopsis thaliana in the bacterial assay, but some of them specifically activated the ZmHK1 receptor from Zea mays and were also more active than the aromatic cytokinin BAP in an ARR5::GUS cytokinin bioassay using transgenic Arabidopsis plants. Whole transcript expression analysis was performed using an Arabidopsis model to gather information about the reprogramming of gene transcription when senescent leaves were treated with selected C2-substituted aromatic cytokinin ribosides. Genome-wide expression profiling revealed that the synthetic halogenated derivatives induced the expression of genes related to cytokinin signaling and metabolism. They also prompted both up- and down-regulation of a unique combination of genes coding for components of the photosystem II (PSII) reaction center, light-harvesting complex II (LHCII), and the oxygen-evolving complex, as well as several stress factors responsible for regulating photosynthesis and chlorophyll degradation. Chlorophyll content and fluorescence analyses demonstrated that treatment with the halogenated derivatives increased the efficiency of PSII photochemistry and the abundance of LHCII relative to DMSO- and BAP-treated controls. These findings demonstrate that it is possible to manipulate and fine-tune leaf longevity using synthetic aromatic cytokinin

  8. Synthesis and antifungal activity of C-21 steroids with an aromatic D ring.

    PubMed

    Sonego, Juan M; Cirigliano, Adriana M; Cabrera, Gabriela M; Burton, Gerardo; Veleiro, Adriana S

    2013-07-01

    Six analogues of salpichrolides with a simplified side chain (6-11) were synthesized using a new methodology to obtain steroids with an aromatic D-ring. The key step was the elimination of HBr in a vicinal dibromo D-homosteroid by treatment with 1,4-diazabicyclo[2.2.2]octane (DABCO). All new compounds were completely characterized by 2D NMR techniques and tested on two fungal pathogenic species, Fusarium virguliforme and Fusarium solani.

  9. Trypanocidal activity and selectivity in vitro of aromatic amidine compounds upon bloodstream and intracellular forms of Trypanosoma cruzi.

    PubMed

    De Souza, E M; da Silva, P B; Nefertiti, A S G; Ismail, M A; Arafa, R K; Tao, B; Nixon-Smith, C K; Boykin, D W; Soeiro, M N C

    2011-02-01

    Trypanosoma cruzi is the etiological agent of Chagas disease, an important neglected illness affecting about 12-14 million people in endemic areas of Latin America. The chemotherapy of Chagas disease is quite unsatisfactory mainly due to its poor efficacy especially during the later chronic phase and the considerable well-known side effects. These facts emphasize the need to search for find new drugs. Diamidines and related compounds are minor groove binders of DNA at AT-rich sites and present excellent anti-trypanosomal activity. In the present study, six novel aromatic amidine compounds (arylimidamides and diamidines) were tested in vitro to determine activity against the infective and intracellular stages of T. cruzi, which are responsible for sustaining the infection in the mammalian hosts. In addition, their selectivity and toxicity towards primary cultures of cardiomyocyte were evaluated since these cells represent important targets of infection and inflammation in vivo. The aromatic amidines were active against T. cruzi in vitro, the arylimidamide DB1470 was the most effective compound presenting a submicromolar LD(50) values, good selectivity index, and good activity at 4 °C in the presence of blood constituents. Our results further justify trypanocidal screening assays with these classes of compounds both in vitro and in vivo in experimental models of T. cruzi infection.

  10. Synthesis and nucleophilic aromatic substitution of 3-fluoro-5-nitro-1-(pentafluorosulfanyl)benzene

    PubMed Central

    Ajenjo, Javier; Greenhall, Martin; Zarantonello, Camillo

    2016-01-01

    Summary 3-Fluoro-5-nitro-1-(pentafluorosulfanyl)benzene was prepared by three different ways: as a byproduct of direct fluorination of 1,2-bis(3-nitrophenyl)disulfane, by direct fluorination of 4-nitro-1-(pentafluorosulfanyl)benzene, and by fluorodenitration of 3,5-dinitro-1-(pentafluorosulfanyl)benzene. The title compound was subjected to a nucleophilic aromatic substitution of the fluorine atom with oxygen, sulfur and nitrogen nucleophiles affording novel (pentafluorosulfanyl)benzenes with 3,5-disubstitution pattern. Vicarious nucleophilic substitution of the title compound with carbon, oxygen, and nitrogen nucleophiles provided 3-fluoro-5-nitro-1-(pentafluorosulfanyl)benzenes substituted in position four. PMID:26977178

  11. Quantitative structure-activity relationship modeling of polycyclic aromatic hydrocarbon mutagenicity by classification methods based on holistic theoretical molecular descriptors.

    PubMed

    Gramatica, Paola; Papa, Ester; Marrocchi, Assunta; Minuti, Lucio; Taticchi, Aldo

    2007-03-01

    Various polycyclic aromatic hydrocarbons (PAHs), ubiquitous environmental pollutants, are recognized mutagens and carcinogens. A homogeneous set of mutagenicity data (TA98 and TA100,+S9) for 32 benzocyclopentaphenanthrenes/chrysenes was modeled by the quantitative structure-activity relationship classification methods k-nearest neighbor and classification and regression tree, using theoretical holistic molecular descriptors. Genetic algorithm provided the selection of the best subset of variables for modeling mutagenicity. The models were validated by leave-one-out and leave-50%-out approaches and have good performance, with sensitivity and specificity ranges of 90-100%. Mutagenicity assessment for these PAHs requires only a few theoretical descriptors of their molecular structure.

  12. Synthesis of Aromatic Retinoids and Curcuminoids and Evaluation of their Antiproliferative, Antiradical, and Anti‐inflammatory Activities

    PubMed Central

    Morzycki, Jacek W.; Rárová, Lucie; Grúz, Jiři; Sawczuk, Tomasz; Kiełczewska, Urszula; Siergiejczyk, Leszek

    2016-01-01

    Abstract Natural retinoids and curcuminoids are known for their broad spectrum of biological properties, such as antioxidant, anti‐inflammatory, antitumor, and so forth. In this work, a convenient synthesis of aromatic retinoids and curcuminoids from vinyl or allyl ketones, and the corresponding alcohols, using olefin metathesis as a key reaction, was elaborated. The best yields and diastereoselectivities were obtained from allylic or homoallylic alcohols by employing the two‐step cross‐metathesis/oxidation procedure. The synthesized analogues were tested for their antiproliferative activity on human cancer cell lines of various origin (leukemia CEM, adenocarcinoma MCF7, cervical carcinoma HeLa) as well as for their antioxidant and anti‐inflammatory activity in vitro. All examined derivatives exhibited strong anti‐inflammatory activity in vitro without affecting cell viability. They also showed strong cytotoxicity against leukemia cell line CEM, except for 18 and 35. The antioxidant activity of the tested compounds was rather weak. PMID:27547644

  13. Synthesis of Aromatic Retinoids and Curcuminoids and Evaluation of their Antiproliferative, Antiradical, and Anti-inflammatory Activities.

    PubMed

    Morzycki, Jacek W; Rárová, Lucie; Grúz, Jiři; Sawczuk, Tomasz; Kiełczewska, Urszula; Siergiejczyk, Leszek; Wojtkielewicz, Agnieszka

    2016-08-01

    Natural retinoids and curcuminoids are known for their broad spectrum of biological properties, such as antioxidant, anti-inflammatory, antitumor, and so forth. In this work, a convenient synthesis of aromatic retinoids and curcuminoids from vinyl or allyl ketones, and the corresponding alcohols, using olefin metathesis as a key reaction, was elaborated. The best yields and diastereoselectivities were obtained from allylic or homoallylic alcohols by employing the two-step cross-metathesis/oxidation procedure. The synthesized analogues were tested for their antiproliferative activity on human cancer cell lines of various origin (leukemia CEM, adenocarcinoma MCF7, cervical carcinoma HeLa) as well as for their antioxidant and anti-inflammatory activity in vitro. All examined derivatives exhibited strong anti-inflammatory activity in vitro without affecting cell viability. They also showed strong cytotoxicity against leukemia cell line CEM, except for 18 and 35. The antioxidant activity of the tested compounds was rather weak. PMID:27547644

  14. Seawater Polluted with Highly Concentrated Polycyclic Aromatic Hydrocarbons Suppresses Osteoblastic Activity in the Scales of Goldfish, Carassius auratus.

    PubMed

    Suzuki, Nobuo; Sato, Masayuki; Nassar, Hossam F; Abdel-Gawad, Fagr Kh; Bassem, Samah M; Yachiguchi, Koji; Tabuchi, Yoshiaki; Endo, Masato; Sekiguchi, Toshio; Urata, Makoto; Hattori, Atsuhiko; Mishima, Hiroyuki; Shimasaki, Youhei; Oshima, Yuji; Hong, Chun-Sang; Makino, Fumiya; Tang, Ning; Toriba, Akira; Hayakawa, Kazuichi

    2016-08-01

    We have developed an original in vitro bioassay using teleost scale, that has osteoclasts, osteoblasts, and bone matrix as each marker: alkaline phosphatase (ALP) for osteoblasts and tartrate-resistant acid phosphatase (TRAP) for osteoclasts. Using this scale in vitro bioassay, we examined the effects of seawater polluted with highly concentrated polycyclic aromatic hydrocarbons (PAHs) and nitro-polycyclic aromatic hydrocarbons (NPAHs) on osteoblastic and osteoclastic activities in the present study. Polluted seawater was collected from two sites (the Alexandria site on the Mediterranean Sea and the Suez Canal site on the Red Sea). Total levels of PAHs in the seawater from the Alexandria and Suez Canal sites were 1364.59 and 992.56 ng/l, respectively. We were able to detect NPAHs in both seawater samples. Total levels of NPAHs were detected in the seawater of the Alexandria site (12.749 ng/l) and the Suez Canal site (3.914 ng/l). Each sample of polluted seawater was added to culture medium at dilution rates of 50, 100, and 500, and incubated with the goldfish scales for 6 hrs. Thereafter, ALP and TRAP activities were measured. ALP activity was significantly suppressed by both polluted seawater samples diluted at least 500 times, but TRAP activity did not change. In addition, mRNA expressions of osteoblastic markers (ALP, osteocalcin, and the receptor activator of the NF-κB ligand) decreased significantly, as did the ALP enzyme activity. In fact, ALP activity decreased on treatment with PAHs and NPAHs. We conclude that seawater polluted with highly concentrated PAHs and NPAHs influences bone metabolism in teleosts. PMID:27498800

  15. Subsite-specific contributions of different aromatic residues in the active site architecture of glycoside hydrolase family 12

    PubMed Central

    Zhang, Xiaomei; Wang, Shuai; Wu, Xiuyun; Liu, Shijia; Li, Dandan; Xu, Hao; Gao, Peiji; Chen, Guanjun; Wang, Lushan

    2015-01-01

    The active site architecture of glycoside hydrolase (GH) is a contiguous subregion of the enzyme constituted by residues clustered in the three-dimensional space, recognizing the monomeric unit of ligand through hydrogen bonds and hydrophobic interactions. Mutations of the key residues in the active site architecture of the GH12 family exerted different impacts on catalytic efficiency. Binding affinities between the aromatic amino acids and carbohydrate rings were quantitatively determined by isothermal titration calorimetry (ITC) and the quantum mechanical (QM) method, showing that the binding capacity order of Tyr>Trp>His (and Phe) was determined by their side-chain properties. The results also revealed that the binding constant of a certain residue remained unchanged when altering its location, while the catalytic efficiency changed dramatically. Increased binding affinity at a relatively distant subsite, such as the mutant of W7Y at the −4 subsite, resulted in a marked increase in the intermediate product of cellotetraose and enhanced the reactivity of endoglucanase by 144%; while tighter binding near the catalytic center, i.e. W22Y at the −2 subsite, enabled the enzyme to bind and hydrolyze smaller oligosaccharides. Clarification of the specific roles of the aromatics at different subsites may pave the way for a more rational design of GHs. PMID:26670009

  16. Aromatic residues in the catalytic center of chitinase A from Serratia marcescens affect processivity, enzyme activity, and biomass converting efficiency.

    PubMed

    Zakariassen, Henrik; Aam, Berit Bjugan; Horn, Svein J; Vårum, Kjell M; Sørlie, Morten; Eijsink, Vincent G H

    2009-04-17

    The processive Serratia marcescens chitinases A (ChiA) and B (ChiB) are thought to degrade chitin in the opposite directions. A recent study of ChiB suggested that processivity is governed by aromatic residues in the +1 and +2 (aglycon) subsites close to the catalytic center. To further investigate the roles of aromatic residues in processivity and to gain insight into the structural basis of directionality, we have mutated Trp(167), Trp(275), and Phe(396) in the -3, +1, and +2 subsites of ChiA, respectively, and characterized the hydrolytic activities of the mutants toward beta-chitin and the soluble chitin-derivative chitosan. Although the W275A and F396A mutants showed only modest reductions in processivity, it was almost abolished by the W167A mutation. Thus, although aglycon subsites seem to steer processivity in ChiB, a glycon (-3) subsite seems to be adapted to do so in ChiA, in line with the notion that the two enzymes have different directionalities. Remarkably, whereas all three single mutants and the W167A/W275A double mutant showed reduced efficiency toward chitin, they showed up to 20-fold higher activities toward chitosan. These results show that the processive mechanism is essential for an efficient conversion of crystalline substrates but comes at a large cost in terms of intrinsic enzyme speed. This needs to be taken into account when devising enzymatic strategies for biomass turnover.

  17. Structure-Activity study of retinoid agonists bearing substituted dicarba-closo-dodecaborane. Relation between retinoidal activity and conformation of two aromatic nuclei.

    PubMed

    Endo, Y; Iijima, T; Yaguchi, K; Kawachi, E; Inoue, N; Kagechika, H; Kubo, A; Itai, A

    2001-05-21

    We have investigated the structure activity relationships of the potent retinoid agonist, 4-[4-(2-propyl-1,2-dicarba-closo-dodecaboran-l-yl)phenylamino]benzoic acid (BR403), which we have previously reported. Substitution of a methyl group on the aromatic nucleus or a methyl group on the nitrogen atom, or replacement of the amino group with ether, methylene, carboxyl or 1,1-ethylene greatly decreased the activity. The relatively planar conformation at the phenyl-N-phenyl moiety seems to play a critical role in the appearance of the biological activity.

  18. Site-directed mutagenesis of tobacco anionic peroxidase: Effect of additional aromatic amino acids on stability and activity.

    PubMed

    Poloznikov, A A; Zakharova, G S; Chubar, T A; Hushpulian, D M; Tishkov, V I; Gazaryan, I G

    2015-08-01

    Tobacco anionic peroxidase (TOP) is known to effectively catalyze luminol oxidation without enhancers, in contrast to horseradish peroxidase (HRP). To pursue structure-activity relationship studies for TOP, two amino acids have been chosen for mutation, namely Thr151, close to the heme plane, and Phe140 at the entrance to the active site pocket. Three mutant forms TOP F140Y, T151W and F140Y/T151W have been expressed in Escherichia coli, and reactivated to yield active enzymes. Single-point mutations introducing additional aromatic amino acid residues at the surface of TOP exhibit a significant effect on the enzyme catalytic activity and stability as judged by the results of steady-state and transient kinetics studies. TOP T151W is up to 4-fold more active towards a number of aromatic substrates including luminol, whereas TOP F140Y is 2-fold more stable against thermal inactivation and 8-fold more stable in the reaction course. These steady-state observations have been rationalized with the help of transient kinetic studies on the enzyme reaction with hydrogen peroxide in a single turnover regime. The stopped-flow data reveal (a) an increased stability of F140Y Compound I towards hydrogen peroxide, and thus, a higher operational stability as compared to the wild-type enzyme, and (b) a lesser leakage of oxidative equivalents from TOP T151W Compound I resulting in the increased catalytic activity. The results obtained show that TOP unique properties can be further improved for practical applications by site-directed mutagenesis.

  19. Effect of Polarity of Activated Carbon Surface, Solvent and Adsorbate on Adsorption of Aromatic Compounds from Liquid Phase.

    PubMed

    Goto, Tatsuru; Amano, Yoshimasa; Machida, Motoi; Imazeki, Fumio

    2015-01-01

    In this study, introduction of acidic functional groups onto a carbon surface and their removal were carried out through two oxidation methods and outgassing to investigate the adsorption mechanism of aromatic compounds which have different polarity (benzene and nitrobenzene). Adsorption experiments for these aromatics in aqueous solution and n-hexane solution were conducted in order to obtain the adsorption isotherms for commercial activated carbon (BAC) as a starting material, its two types of oxidized BAC samples (OXs), and their outgassed samples at 900 °C (OGs). Adsorption and desorption kinetics of nitrobenzene for the BAC, OXs and OGs in aqueous solution were also examined. The results showed that the adsorption of benzene molecules was significantly hindered by abundant acidic functional groups in aqueous solution, whereas the adsorbed amount of nitrobenzene on OXs gradually increased as the solution concentration increased, indicating that nitrobenzene can adsorb favourably on a hydrophilic surface due to its high dipole moment, in contrast to benzene. In n-hexane solution, it was difficult for benzene to adsorb on any sample owing to the high affinity between benzene and n-hexane solvent. On the other hand, adsorbed amounts of nitrobenzene on OXs were larger than those of OGs in n-hexane solution, implying that nitrobenzene can adsorb two adsorption sites, graphene layers and surface acidic functional groups. The observed adsorption and desorption rate constants of nitrobenzene on the OXs were lower than those on the BAC due to disturbance of diffusion by the acidic functional groups.

  20. Mosquito repellent activity of essential oils of aromatic plants growing in Argentina.

    PubMed

    Gillij, Y G; Gleiser, R M; Zygadlo, J A

    2008-05-01

    Mosquitoes are important vectors of diseases and nuisance pests. Repellents minimize contact with mosquitoes. Repellents based on essential oils (EO) are being developed as an alternative to DEET (N,N-diethyl-m-methylbenzamide), an effective compound that has disadvantages including toxic reactions, and damage to plastic and synthetic fabric. This work evaluated the repellency against Aedes aegypti of EO from aromatic plants that grow in Argentina: Acantholippia seriphioides, Achyrocline satureioides, Aloysia citriodora, Anemia tomentosa, Baccharis spartioides, Chenopodium ambrosioides, Eucalyptus saligna, Hyptis mutabilis, Minthostachys mollis, Rosmarinus officinalis, Tagetes minuta and Tagetes pusilla. Most EO were effective. Variations depending on geographic origin of the plant were detected. At a 90% EO concentration, A. satureoides and T. pusilla were the least repellent. At concentrations of 12.5% B. spartioides, R. officinalis and A. citriodora showed the longest repellency times. Comparisons of the principal components of each EO suggest that limonene and camphor were the main components responsible for the repellent effects.

  1. Mosquito repellent activity of essential oils of aromatic plants growing in Argentina.

    PubMed

    Gillij, Y G; Gleiser, R M; Zygadlo, J A

    2008-05-01

    Mosquitoes are important vectors of diseases and nuisance pests. Repellents minimize contact with mosquitoes. Repellents based on essential oils (EO) are being developed as an alternative to DEET (N,N-diethyl-m-methylbenzamide), an effective compound that has disadvantages including toxic reactions, and damage to plastic and synthetic fabric. This work evaluated the repellency against Aedes aegypti of EO from aromatic plants that grow in Argentina: Acantholippia seriphioides, Achyrocline satureioides, Aloysia citriodora, Anemia tomentosa, Baccharis spartioides, Chenopodium ambrosioides, Eucalyptus saligna, Hyptis mutabilis, Minthostachys mollis, Rosmarinus officinalis, Tagetes minuta and Tagetes pusilla. Most EO were effective. Variations depending on geographic origin of the plant were detected. At a 90% EO concentration, A. satureoides and T. pusilla were the least repellent. At concentrations of 12.5% B. spartioides, R. officinalis and A. citriodora showed the longest repellency times. Comparisons of the principal components of each EO suggest that limonene and camphor were the main components responsible for the repellent effects. PMID:17583499

  2. A polymorph of 2,4-dinitro­phenyl­hydrazine

    PubMed Central

    Amimoto, Kiichi; Nishiguchi, Hiromitsu

    2013-01-01

    The crystal structure of a previously unreported polymorph (form II) of 2,4-dinitro­phenyl­hydrazine (DNPH), C6H6N4O4, was determined at 90 K. The first polymorph (form I) is described in the monoclinic space group P21/c [Okabe et al. (1993 ▶). Acta Cryst. C49, 1678–1680; Wardell et al. (2006 ▶). Acta Cryst. C62, o318–320], whereas form II is in the monoclinic space group Cc. The mol­ecular structures in forms I and II are closely similar, with the nitro groups at the 2- and 4-positions being almost coplanar with the benzene ring [dihedral angles of 3.54 (1) and 3.38 (1)°, respectively in II]. However, their packing arrangements are completely different. Form I exhibits a herringbone packing motif, whereas form II displays a coplanar chain structure. Each chain in form II is connected to adjacent chains by the inter­molecular inter­action between hydrazine NH2 and 2-nitro groups, forming a sheet normal to (101). The sheet is stabilized by N—H⋯π inter­actions. PMID:23476598

  3. Synthesis and Thermal Decomposition Mechanism of the Energetic Compound 3,5-Dinitro-4-nitroxypyrazole

    NASA Astrophysics Data System (ADS)

    Feng, Xiao-Qin; Cao, Duan-Lin; Cui, Jian-Lan

    2016-07-01

    A novel energetic material, 3,5-dinitro-4-nitroxypyrazole (DNNP), was synthesized via nitration and nucleophilic substitution reaction using 4-chloropyrazole as raw material. The structure of DNNP was characterized by Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), and elemental analysis. Its detonation properties were calculated and compared with those of other commonly used energetic compounds. The thermal decomposition mechanism of DNNP was studied by means of thermogravimetry and differential scanning calorimetry coupled with a mass spectrometry (DSC-MS). The results show that the detonation properties of DNNP were better than those of TNT and comparable to those of 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). In addition, the thermal decomposition mechanism of DNNP was supposed. Initially, the O-NO2 bond was broken, thereby producing a nitropyrazole oxygen radical. Subsequently, the nitropyrazole oxygen radical was decomposed by free radical cleavage of nitro or isomerized to nitritepyrazole and subsequently decomposed by free radical cleavage of the nitroso group. Finally, pyrazole ring fission occurred and produced N2, NO, N2O, and CO2.

  4. The Toluene o-Xylene Monooxygenase Enzymatic Activity for the Biosynthesis of Aromatic Antioxidants

    PubMed Central

    Pizzo, Elio; Notomista, Eugenio; Pezzella, Alessandro; Di Cristo, Carlo; De Lise, Federica; Di Donato, Alberto; Izzo, Viviana

    2015-01-01

    Monocyclic phenols and catechols are important antioxidant compounds for the food and pharmaceutic industries; their production through biotransformation of low-added value starting compounds is of major biotechnological interest. The toluene o-xylene monooxygenase (ToMO) from Pseudomonas sp. OX1 is a bacterial multicomponent monooxygenase (BMM) that is able to hydroxylate a wide array of aromatic compounds and has already proven to be a versatile biochemical tool to produce mono- and dihydroxylated derivatives of aromatic compounds. The molecular determinants of its regioselectivity and substrate specificity have been thoroughly investigated, and a computational strategy has been developed which allows designing mutants able to hydroxylate non-natural substrates of this enzyme to obtain high-added value compounds of commercial interest. In this work, we have investigated the use of recombinant ToMO, expressed in cells of Escherichia coli strain JM109, for the biotransformation of non-natural substrates of this enzyme such as 2-phenoxyethanol, phthalan and 2-indanol to produce six hydroxylated derivatives. The hydroxylated products obtained were identified, isolated and their antioxidant potential was assessed both in vitro, using the DPPH assay, and on the rat cardiomyoblast cell line H9c2. Incubation of H9c2 cells with the hydroxylated compounds obtained from ToMO-catalyzed biotransformation induced a differential protective effect towards a mild oxidative stress induced by the presence of sodium arsenite. The results obtained confirm once again the versatility of the ToMO system for oxyfunctionalization reactions of biotechnological importance. Moreover, the hydroxylated derivatives obtained possess an interesting antioxidant potential that encourages the use of the enzyme for further functionalization reactions and their possible use as scaffolds to design novel bioactive molecules. PMID:25915063

  5. The Toluene o-Xylene Monooxygenase Enzymatic Activity for the Biosynthesis of Aromatic Antioxidants.

    PubMed

    Donadio, Giuliana; Sarcinelli, Carmen; Pizzo, Elio; Notomista, Eugenio; Pezzella, Alessandro; Di Cristo, Carlo; De Lise, Federica; Di Donato, Alberto; Izzo, Viviana

    2015-01-01

    Monocyclic phenols and catechols are important antioxidant compounds for the food and pharmaceutic industries; their production through biotransformation of low-added value starting compounds is of major biotechnological interest. The toluene o-xylene monooxygenase (ToMO) from Pseudomonas sp. OX1 is a bacterial multicomponent monooxygenase (BMM) that is able to hydroxylate a wide array of aromatic compounds and has already proven to be a versatile biochemical tool to produce mono- and dihydroxylated derivatives of aromatic compounds. The molecular determinants of its regioselectivity and substrate specificity have been thoroughly investigated, and a computational strategy has been developed which allows designing mutants able to hydroxylate non-natural substrates of this enzyme to obtain high-added value compounds of commercial interest. In this work, we have investigated the use of recombinant ToMO, expressed in cells of Escherichia coli strain JM109, for the biotransformation of non-natural substrates of this enzyme such as 2-phenoxyethanol, phthalan and 2-indanol to produce six hydroxylated derivatives. The hydroxylated products obtained were identified, isolated and their antioxidant potential was assessed both in vitro, using the DPPH assay, and on the rat cardiomyoblast cell line H9c2. Incubation of H9c2 cells with the hydroxylated compounds obtained from ToMO-catalyzed biotransformation induced a differential protective effect towards a mild oxidative stress induced by the presence of sodium arsenite. The results obtained confirm once again the versatility of the ToMO system for oxyfunctionalization reactions of biotechnological importance. Moreover, the hydroxylated derivatives obtained possess an interesting antioxidant potential that encourages the use of the enzyme for further functionalization reactions and their possible use as scaffolds to design novel bioactive molecules.

  6. The luminous polycyclic aromatic hydrocarbon emission features: Applications to high redshift galaxies and active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Shipley, Heath Vernon

    The co-evolution of star-formation and supermassive black hole (SMBH) accretion in galaxies is one of the key problems in galaxy formation theory. Understanding the formation of galaxies, and their subsequent evolution, will be coupled to intensive study of the evolution of SMBHs. This thesis focuses on studying diagnostics of star-formation and SMBH accretion to develop tools to study this co-evolution. Chapter 2 consists of using mid-infrared (mid-IR) spectroscopy from the Spitzer Infrared Spectrograph (IRS) to study the nature of star-formation and SMBH accretion. The mid-IR spectra cover wavelengths 5-38mum, spanning the polycyclic aromatic hydrocarbon (PAH) features and important atomic diagnostic lines. We divide our sample into a subsample of galaxies with Spitzer IRAC colors indicative of warm dust heated by an AGN (IRAGN) and those galaxies whose colors indicate star-formation processes (non-IRAGN). In both the IRAGN and star-forming samples, the luminosity in the PAH features correlates strongly with [Ne II]lambda12.8&mum emission line, from which we conclude that the PAH luminosity directly traces the instantaneous star-formation rate (SFR) in both the IRAGN and star-forming galaxies. There is no measurable difference between the PAH luminosity ratios of L11:3/L7:7 and L6:2/L7:7 for the IRAGN and non-IRAGN, suggesting that AGN do not significantly excite or destroy PAH molecules on galaxy-wide scales. In chapter 3, I calibrate the PAH luminosity as a SFR indicator. We provide a new robust SFR calibration using the luminosity emitted from PAH molecules at 6.2mum, 7.7mum and 11.3mum. The PAH features emit strongly in the mid-IR mitigating dust extinction, containing on average 5--10% of the total IR luminosity in galaxies. We use mid-IR spectroscopy from the Spitzer/IRS, and data covering other SFR indicators (Halpha emission and rest-frame 24mum continuum emission). The PAH luminosity correlates linearly with the SFR as measured by the Halpha luminosity

  7. Pattern of aromatic and hydrophobic amino acids critical for one of two subdomains of the VP16 transcriptional activator.

    PubMed Central

    Regier, J L; Shen, F; Triezenberg, S J

    1993-01-01

    Structural features of the transcriptional activation domain of the herpes simplex virion protein VP16 were examined by oligonucleotide-directed mutagenesis. Extensive mutagenesis at position 442 of the truncated VP16 activation domain (delta 456), normally occupied by a phenylalanine residue, demonstrated the importance of an aromatic amino acid at that position. On the basis of an alignment of the VP16 sequence surrounding Phe-442 and the sequences of other transcriptional activation domains, we subjected leucine residues at positions 439 and 444 of VP16 to mutagenesis. Results from these experiments suggest that bulky hydrophobic residues flanking Phe-442 also contribute significantly to the function of the truncated VP16 activation domain. Restoration of amino acids 457-490 to various Phe-442 mutants partially restored activity. Although the pattern of amino acids surrounding Phe-473 resembles that surrounding Phe-442, mutations of Phe-473 did not dramatically affect activity; in fact, Phe-475 appears more sensitive to mutations than does Phe-473. We infer that the two regions of VP16 (amino acids 413-456 and 457-490) possess unique structural features, although neither is likely to be an amphipathic alpha-helix or an "acidic blob." These results, considered with previous in vitro activation and inhibition studies, suggest that the two subdomains of VP16 affect transcription by different mechanisms. Images PMID:8381535

  8. POLYCYCLIC AROMATIC HYDROCARBONS IN GALAXIES AT z approx 0.1: THE EFFECT OF STAR FORMATION AND ACTIVE GALACTIC NUCLEI

    SciTech Connect

    O'Dowd, Matthew J.; Schiminovich, David; Johnson, Benjamin D.; Treyer, Marie A.; Martin, Christopher D.; Wyder, Ted K.; Charlot, S.; Heckman, Timothy M.; Martins, Lucimara P.; Seibert, Mark; Van der Hulst, J. M.

    2009-11-01

    We present the analysis of the polycyclic aromatic hydrocarbon (PAH) spectra of a sample of 92 typical star-forming galaxies at 0.03 < z < 0.2 observed with the Spitzer intensified Reticon spectrograph (IRS). We compare the relative strengths of PAH emission features with Sloan Digital Sky Survey optical diagnostics to probe the relationship between PAH grain properties and star formation and active galactic nuclei (AGNs) activity. Short-to-long wavelength PAH ratios, and in particular the 7.7 mum-to-11.3 mum feature ratio, are strongly correlated with the star formation diagnostics D{sub n} (4000) and Halpha equivalent width, increasing with younger stellar populations. This ratio also shows a significant difference between active and non-active galaxies, with the active galaxies exhibiting weaker 7.7 mum emission. A hard radiation field as measured by [O{sub III}]/Hbeta and [Ne{sub III}]{sub 15.6m}u{sub m}/[Ne{sub II}]{sub 12.8m}u{sub m} effects PAH ratios differently depending on whether this field results from starburst activity or an AGN. Our results are consistent with a picture in which larger PAH molecules grow more efficiently in richer media and in which smaller PAH molecules are preferentially destroyed by the AGN.

  9. Hydrogen bonds and a hydrogen-bonded chain in mannich bases of 5,5'-dinitro-2,2'-biphenol-FT-IR and 1H NMR studies

    NASA Astrophysics Data System (ADS)

    Brzezinski, Bogumil; Urjasz, Hanna; Bartl, Franz; Zundel, Georg

    1997-11-01

    5,5'-Dinitro-3-diethylaminomethyl-2,2'-biphenol ( 1) and 5,5'-dinitro-3,3' bis(diethylaminomethyl)-2,2'-biphenol ( 2) as well as 5,5'-dinitro-2,2'-biphenol ( 3) were synthesized and studied by FT-IR and 1H NMR spectroscopy in acetonitrile or acetonitrile-d 3 solutions, respectively. With compound 1 a hydrogen-bonded system with large proton polarizability is found. In the hydrogen bonds in compound 2 the protons are localized at the N atoms. These hydrogen bonds show no proton polarizability. In the protonated compound 2 a very strong homoconjugated -O⋯H +⋯O - hydrogen bond with large proton polarizability is found, whereas two other protons are localized at the N atoms. The deviation of the results obtained with other derivatives of 2,2'-biphenols are caused by the larger acidity of the nitro groups.

  10. Indole-3-acetic acid biosynthetic pathway and aromatic amino acid aminotransferase activities in Pantoea dispersa strain GPK.

    PubMed

    Kulkarni, G B; Nayak, A S; Sajjan, S S; Oblesha, A; Karegoudar, T B

    2013-05-01

    This investigation deals with the production of IAA by a bacterial isolate Pantoea dispersa strain GPK (PDG) identified by 16S rRNA gene sequence analysis. HPLC and Mass spectral analysis of metabolites from bacterial spent medium revealed that, IAA production by PDG is Trp-dependent and follows indole-3-pyruvic acid (IPyA) pathway. Substrate specificity study of aromatic amino acid aminotransferase (AAT) showed high activities, only when tryptophan (Trp) and α-ketoglutarate (α-kg) were used as substrates. AAT is highly specific for Trp and α-kg as amino group donor and acceptor, respectively. The effect of exogenous IAA on bacterial growth was established. Low concentration of exogenous IAA induced the growth, whereas high concentration decreased the growth of bacterium. PDG treatment significantly increased the root length, shoot length and dry mass of the chickpea and pigeon pea plants. PMID:23448265

  11. Non-ovarian aromatization is required to activate female sexual motivation in testosterone-treated ovariectomized quail.

    PubMed

    de Bournonville, Catherine; Balthazart, Jacques; Ball, Gregory F; Cornil, Charlotte A

    2016-07-01

    Although aromatase is expressed in both male and female brains, its functional significance in females remains poorly understood. In female quail, sexual receptivity is activated by estrogens. However it is not known whether sexual motivation is similarly estrogen-dependent and whether estrogens locally produced in the brain contribute to these behavioral responses. Four main experiments were designed to address these questions. In Experiment 1 chronic treatment of females with the anti-estrogen tamoxifen decreased their receptivity, confirming that this response is under the control of estrogens. In Experiment 2 chronic treatment with tamoxifen significantly decreased sexual motivation as treated females no longer approached a sexual partner. In Experiment 3 (a) ovariectomy (OVX) induced a significant decrease of time spent near the male and a significantly decreased receptivity compared to gonadally intact females, (b) treatment with testosterone (OVX+T) partially restored these responses and (c) this effect of T was prevented when estradiol synthesis was inhibited by the potent aromatase inhibitor Vorozole (OVX+T+VOR). Serum estradiol concentration was significantly higher in OVX+T than in OVX or OVX+T+VOR females. Together these data demonstrate that treatment of OVX females with T increases sexual motivation and that these effects are mediated at least in part by non-gonadal aromatization of the androgen. Finally, assays of aromatase activity on brain and peripheral tissues (Experiment 4) strongly suggest that brain aromatization contributes to behavioral effects observed here following T treatment but alternative sources of estrogens (e.g. liver) should also be considered. PMID:27189762

  12. Non-ovarian aromatization is required to activate female sexual motivation in testosterone-treated ovariectomized quail.

    PubMed

    de Bournonville, Catherine; Balthazart, Jacques; Ball, Gregory F; Cornil, Charlotte A

    2016-07-01

    Although aromatase is expressed in both male and female brains, its functional significance in females remains poorly understood. In female quail, sexual receptivity is activated by estrogens. However it is not known whether sexual motivation is similarly estrogen-dependent and whether estrogens locally produced in the brain contribute to these behavioral responses. Four main experiments were designed to address these questions. In Experiment 1 chronic treatment of females with the anti-estrogen tamoxifen decreased their receptivity, confirming that this response is under the control of estrogens. In Experiment 2 chronic treatment with tamoxifen significantly decreased sexual motivation as treated females no longer approached a sexual partner. In Experiment 3 (a) ovariectomy (OVX) induced a significant decrease of time spent near the male and a significantly decreased receptivity compared to gonadally intact females, (b) treatment with testosterone (OVX+T) partially restored these responses and (c) this effect of T was prevented when estradiol synthesis was inhibited by the potent aromatase inhibitor Vorozole (OVX+T+VOR). Serum estradiol concentration was significantly higher in OVX+T than in OVX or OVX+T+VOR females. Together these data demonstrate that treatment of OVX females with T increases sexual motivation and that these effects are mediated at least in part by non-gonadal aromatization of the androgen. Finally, assays of aromatase activity on brain and peripheral tissues (Experiment 4) strongly suggest that brain aromatization contributes to behavioral effects observed here following T treatment but alternative sources of estrogens (e.g. liver) should also be considered.

  13. Simultaneous removal of sulfur dioxide and polycyclic aromatic hydrocarbons from incineration flue gas using activated carbon fibers.

    PubMed

    Liu, Zhen-Shu; Li, Wen-Kai; Hung, Ming-Jui

    2014-09-01

    Incineration flue gas contains polycyclic aromatic hydrocarbons (PAHs) and sulfur dioxide (SO2). The effects of SO2 concentration (0, 350, 750, and 1000 ppm), reaction temperature (160, 200, and 280 degrees C), and the type of activated carbon fibers (ACFs) on the removal of SO2 and PAHs by ACFs were examined in this study. A fluidized bed incinerator was used to simulate practical incineration flue gas. It was found that the presence of SO2 in the incineration flue gas could drastically decrease removal of PAHs because of competitive adsorption. The effect of rise in the reaction temperature from 160 to 280 degrees C on removal of PAHs was greater than that on SO2 removal at an SO2 concentration of 750 ppm. Among the three ACFs studied, ACF-B, with the highest microporous volume, highest O content, and the tightest structure, was the best adsorbent for removing SO2 and PAHs when these gases coexisted in the incineration flue gas. Implications: Simultaneous adsorption of sulfur dioxide (SO2) and polycyclic aromatic hydrocarbons (PAHs) emitted from incineration flue gas onto activated carbon fibers (ACFs) meant to devise a new technique showed that the presence of SO2 in the incineration flue gas leads to a drastic decrease in removal of PAHs because of competitive adsorption. Reaction temperature had a greater influence on PAHs removal than on SO2 removal. ACF-B, with the highest microporous volume, highest O content, and tightest structure among the three studied ACFs, was found to be the best adsorbent for removing SO2 and PAHs.

  14. Synthesis, structure, and magnetic and catalytic properties of metal frameworks with 2,2'-dinitro-4,4'-biphenyldicarboxylate and imidazole-containing tripodal ligands.

    PubMed

    Li, Yu-Ling; Zhao, Dan; Zhao, Yue; Wang, Peng; Wang, Huai-Wei; Sun, Wei-Yin

    2016-06-01

    Based on 1,3,5-tris(1-imidazolyl)benzene (tib) and 2,2'-dinitro-4,4'-biphenyldicarboxylic acid (H2dnbpdc), four new metal-organic frameworks [M3(tib)(dnbpdc)3(H2O)2] [M = Mn (1), Cd (2)], [Zn3(tib)2(dnbpdc)2.5(Hdnbpdc)]·4DEF (3), and [Cd(tib)(dnbpdc)(H2O)]·DMF·H2O (4) (DEF = N,N-diethylformamide, DMF = N,N-dimethylformamide) were successfully synthesized. Isomeric 1 and 2 were unusual 8-connected uninodal three-dimensional (3D) frameworks with a point symbol of {3(3)·4(15)·5(9)·6}. Compound 3 was a (3,3,4,4)-connected 4-nodal 3D net with a point symbol of {4·6·8}2{4·6(2)}{4·8(5)}{6(2)·8(3)·10}, whereas 4 was a one-dimensional (1D) chain, which was further linked with neighboring 1D chains by hydrogen bonding interactions to give a 3D framework. It is interesting that 1 displayed ferromagnetic and antiferromagnetic interactions within the trinuclear Mn(ii) subunit. We also performed Knoevenagel condensation reactions catalyzed by activated 3 to demonstrate its heterogeneous catalytic property. Furthermore, the adsorption property of 3 was also investigated. PMID:27147248

  15. Aromatic L-amino acids activate the calcium-sensing receptor.

    PubMed

    Conigrave, Arthur D; Mun, Hee-Chang; Lok, Hiu-Chuen

    2007-06-01

    The calcium-sensing receptor (CaR) is recognized as a member of class 3 of the G-protein coupled receptor superfamily. Members of this subgroup, which have large N-terminal extracellular domains, include receptors that respond specifically to the amino acid glutamate; receptors that respond to the glutamate analogue, gamma-amino butyric acid; and several receptors that act as broad-spectrum amino acid sensors. The CaR is one of these broad-spectrum amino acid sensors that, along with several other members of the subgroup, also responds to extracellular Ca2+. In this mini-review, we consider evidence that the CaR is a sensor of aromatic amino acids, that it has broad-spectrum amino acid sensing properties, that it provides an amino acid binding site in its extracellular N-terminal Venus Fly Trap domain, and that amino acids have a physiological impact on systems in which the CaR is expressed.

  16. Aromatic Interactions in Organocatalyst Design: Augmenting Selectivity Reversal in Iminium Ion Activation.

    PubMed

    Holland, Mareike C; Metternich, Jan Benedikt; Daniliuc, Constantin; Schweizer, W Bernd; Gilmour, Ryan

    2015-07-01

    Substituting N-methylpyrrole for N-methyindole in secondary-amine-catalysed Friedel-Crafts reactions leads to a curious erosion of enantioselectivity. In extreme cases, this substrate dependence can lead to an inversion in the sense of enantioinduction. Indeed, these closely similar transformations require two structurally distinct catalysts to obtain comparable selectivities. Herein a focussed molecular editing study is disclosed to illuminate the structural features responsible for this disparity, and thus identify lead catalyst structures to further exploit this selectivity reversal. Key to effective catalyst re-engineering was delineating the non-covalent interactions that manifest themselves in conformation. Herein we disclose preliminary validation that intermolecular aromatic (CH-π and cation-π) interactions between the incipient iminium cation and the indole ring system is key to rationalising selectivity reversal. This is absent in the N-methylpyrrole alkylation, thus forming the basis of two competing enantio-induction pathways. A simple L-valine catalyst has been developed that significantly augments this interaction. PMID:25982418

  17. Isolation and identification of aromatic compounds in Lion's Mane Mushroom and their anticancer activities.

    PubMed

    Li, Wei; Zhou, Wei; Kim, Eun-Ji; Shim, Sang Hee; Kang, Hee Kyoung; Kim, Young Ho

    2015-03-01

    Lion's Mane Mushroom (Hericium erinaceum) is a traditional edible mushroom widely used in culinary applications and as an herbal medicine in East Asian countries. In the present study, two new aromatic compounds, hericerin A (1) and isohericenone J (5), along with five known compounds, isoericerin (2), hericerin (3), N-De phenylethyl isohericerin (4), hericenone J (6), and 4-[3',7'-dimethyl-2',6'-octadienyl]-2-formyl-3-hydroxy-5-methyoxybenzylalcohol (7), were isolated from a methanol extract of the fruiting bodies of H. erinaceum. The chemical structures of the compounds were determined from mass spectra and 1D- and 2D NMR spectroscopy. The anticancer effects of the isolated compounds were examined in HL-60 human acute promyelocytic leukaemia cells. Hericerin A (1) and hericerin (3) significantly reduced cell proliferation with IC50 values of 3.06 and 5.47 μM, respectively. These same compounds also induced apoptosis of HL-60 cells, accompanied by time-dependent down-regulation of p-AKT and c-myc levels. These data suggest that compounds 1 and 3 from H. erinaceum are suitable for use in potential cancer treatments.

  18. Structure-plant phytotoxic activity relationship of 7,7'-epoxylignanes, (+)- and (-)-verrucosin: simplification on the aromatic ring substituents.

    PubMed

    Yamauchi, Satoshi; Nakayama, Kumiko; Nishiwaki, Hisashi; Shuto, Yoshihiro

    2014-10-15

    The synthesized 7-aryl derivatives of (7R,7'S,8S,8'S)-(+)-verrucosin were applied to growth inhibitory activity test against ryegrass at 1mM. 7-(3-Ethoxy-4-hydroxyphenyl) derivative 12 and 7-(2-hydroxyphenyl) derivative 4 showed comparable activity to those of (+)-verrucosin against the root (-95%) and the shoot (-60%), respectively. The growth inhibitory activity test against lettuce using synthesized 7-aryl derivatives of (7S,7'R,8R,8'R)-(-)-verrucosin at 1mM showed that the activities of 7-(3-hydroxyphenyl) derivative 20 and 7-(3-ethoxy-4-hydroxyphenyl) derivative 28 are similar to that of (-)-verrucosin against the root (-95%). Against the shoot, 7-(3-hydroxyphenyl) derivative 20 showed higher activity (-80%) than that of (-)-verrucosin (-60%). As the next step, (7S,7'R,8R,8'R)-7-(3-hydroxyphenyl)-7'-aryl-(-)-verrucosin derivatives, in which the most effective 3-hydroxyphenyl group is employed as 7-aromatic ring, were synthesized for the assay against lettuce. In this experiment, 7'-(2-hydroxyphenyl) derivative 37 and 7'-(3-hydroxyphenyl) derivative 38 showed similar activity to that of derivative 20. The effect of 7- and 7'-aryl structures of 7,7'-epoxylignanes on the plant growth inhibitory activity was clarified. The 7- and 7'-aryl structures were simplified to show comparable activity to or higher activity than that of (-)-verrucosin. The plant growth inhibitory activity of a nutmeg component, (+)-fragransin C3b, was estimated as -80% inhibition at 1mM against ryegrass roots. PMID:25248684

  19. Metal-ligand cooperation by aromatization-dearomatization: a new paradigm in bond activation and "green" catalysis.

    PubMed

    Gunanathan, Chidambaram; Milstein, David

    2011-08-16

    In view of global concerns regarding the environment and sustainable energy resources, there is a strong need for the discovery of new, green catalytic reactions. For this purpose, fresh approaches to catalytic design are desirable. In recent years, complexes based on "cooperating" ligands have exhibited remarkable catalytic activity. These ligands cooperate with the metal center by undergoing reversible structural changes in the processes of substrate activation and product formation. We have discovered a new mode of metal-ligand cooperation, involving aromatization-dearomatization of ligands. Pincer-type ligands based on pyridine or acridine exhibit such cooperation, leading to unusual bond activation processes and to novel, environmentally benign catalysis. Bond activation takes place with no formal change in the metal oxidation state, and so far the activation of H-H, C-H (sp(2) and sp(3)), O-H, and N-H bonds has been demonstrated. Using this approach, we have demonstrated a unique water splitting process, which involves consecutive thermal liberation of H(2) and light-induced liberation of O(2), using no sacrificial reagents, promoted by a pyridine-based pincer ruthenium complex. An acridine pincer complex displays unique "long-range" metal-ligand cooperation in the activation of H(2) and in reaction with ammonia. In this Account, we begin by providing an overview of the metal-ligand cooperation based on aromatization-dearomatization processes. We then describe a range of novel catalytic reactions that we developed guided by these new modes of metal-ligand cooperation. These reactions include the following: (1) acceptorless dehydrogenation of secondary alcohols to ketones, (2) acceptorless dehydrogenative coupling of alcohols to esters, (3) acylation of secondary alcohols by esters with dihydrogen liberation, (4) direct coupling of alcohols and amines to form amides and polyamides with liberation of dihydrogen, (5) coupling of esters and amines to form amides

  20. Synthesis and Properties of a New Explosive, 4-Amino-3,5-Dinitro-lH-Pyrazole (LLM-116)

    SciTech Connect

    Schmidt, R D; Lee, G S; Pagoria, P F; Mitchell, A R; Gilardi, R

    2001-05-22

    A novel synthesis of the title compound was achieved by direct amination using Vicarious Nucleophilic Substitution (VNS) methodology. Reaction of 1,1,1-trimethylhydrazinium iodide with 3,5-dinitropyrazole in DMSO produces 4-amino-3,s-dinitro-1H-pyrazole as a 1:1 crystal solvate with DMSO. Recrystallization from water yields the monohydrated crystal. Recrystallization of the monohydrate from butyl acetate yields the compound in pure form. Crystallographic data and results of small-scale safety tests are reported. These data indicate that LLM-116 is a promising candidate as an insensitive high explosive.

  1. DEPENDENCY OF POLYCHLORINATED BIPHENYL AND POLYCYCLIC AROMATIC HYDROCARBON BIOACCUMULATION IN MYA ARENARIA ON BOTH WATER COLUMN AND SEDIMENT BED CHEMICAL ACTIVITIES

    EPA Science Inventory

    The bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) by the filter-feeding soft-shell clam Mya arenaria was evaluated at three sites near Boston (MA, USA) by assessing the chemical activities of those hydrophobic organic compounds (H...

  2. The Luminous Polycyclic Aromatic Hydrocarbon Emission Features: Applications to High Redshift Galaxies and Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Shipley, Heath; Papovich, Casey

    2015-08-01

    We provide a new robust star-formation rate (SFR) calibration using the luminosity from polycyclic aromatic hydrogen (PAH) molecules. The PAH features emit strongly in the mid-infrared (mid-IR; 3-19μm), mitigating dust extinction, and they are very luminous, containing 5-10% of the total IR luminosity in galaxies. We derive the calibration of the PAH luminosity as a SFR indicator using a sample of 105 star-forming galaxies covering a range of total IR luminosity, LIR = L(8-1000μm) = 109 - 1012 L⊙ and redshift 0 < z < 0.6. The PAH luminosity correlates linearly with the SFR as measured by the dust-corrected Hα luminosity (using the sum of the Hα and rest-frame 24μm luminosity from Kennicutt et al. 2009), with tight scatter of ~0.15 dex, comparable to the scatter in the dust-corrected Hα SFRs and Paα SFRs. We show this relation is sensitive to galaxy metallicity, where the PAH luminosity of galaxies with Z < 0.7 Z⊙ departs from the linear SFR relationship but in a behaved manor. We derive for this a correction to galaxies below solar metallicity. As a case study for observations with JWST, we apply the PAH SFR calibration to a sample of lensed galaxies at 1 < z < 3 with Spitzer Infrared Spectrograph (IRS) data, and we demonstrate the utility of PAHs to derive SFRs as accurate as those available from any other indicator. This new SFR indicator will be useful for probing the peak of the SFR density of the universe (1 < z < 3) and for studying the coevolution of star-formation and supermassive blackhole accretion contemporaneously in a galaxy.

  3. Uptake and toxicity of polycyclic aromatic hydrocarbons in terrestrial springtails--studying bioconcentration kinetics and linking toxicity to chemical activity.

    PubMed

    Schmidt, Stine Nørgaard; Smith, Kilian Eric Christopher; Holmstrup, Martin; Mayer, Philipp

    2013-02-01

    Passive dosing applies a polymer loaded with test compound(s) to establish and maintain constant exposure in laboratory experiments. Passive dosing with the silicone poly(dimethylsiloxane) was used to control exposure of the terrestrial springtail Folsomia candida to six polycyclic aromatic hydrocarbons (PAHs) in bioconcentration and toxicity experiments. Folsomia candida could move freely on the PAH-loaded silicone, resulting in exposure via air and direct contact. The bioconcentration kinetics indicated efficient uptake of naphthalene, anthracene, and pyrene through air and (near) equilibrium partitioning of these PAHs to lipids and possibly the waxy layer of the springtail cuticle. Toxicities of naphthalene, phenanthrene, and pyrene were related to chemical activity, which quantifies the energetic level and drives spontaneous processes including diffusive biouptake. Chemical activity-response relationships yielded effective lethal chemical activities (La50s) well within the expected range for baseline toxicity (0.01-0.1). Effective lethal body burdens for naphthalene and pyrene exceeded the expected range of 2 to 8 mmol kg(-1) fresh weight, which again indicated the waxy layer to be a sorbing phase. Finally, chemical activities were converted into equilibrium partitioning concentrations in lipids yielding effective lethal concentrations for naphthalene and phenanthrene in good correspondence with the lethal membrane burden for baseline toxicity (40-160 mmol kg(-1) lipid). Passive dosing was a practical approach for tightly controlling PAH exposure, which in turn provided new experimental possibilities and findings. PMID:23147567

  4. Activation of group IVC phospholipase A(2) by polycyclic aromatic hydrocarbons induces apoptosis of human coronary artery endothelial cells.

    PubMed

    Tithof, Patricia K; Richards, Sean M; Elgayyar, Mona A; Menn, Fu-Minn; Vulava, Vijay M; McKay, Larry; Sanseverino, John; Sayler, Gary; Tucker, Dawn E; Leslie, Christina C; Lu, Kim P; Ramos, Kenneth S

    2011-06-01

    Exposure to environmental pollutants, such as polycyclic aromatic hydrocarbons (PAHs) found in coal tar mixtures and tobacco sources, is considered a significant risk factor for the development of heart disease in humans. The goal of this study was to determine the influence of PAHs present at a Superfund site on human coronary artery endothelial cell (HCAEC) phospholipase A(2) (PLA(2)) activity and apoptosis. Extremely high levels of 12 out of 15 EPA high-priority PAHs were present in both the streambed and floodplain sediments at a site where an urban creek and its adjacent floodplain were extensively contaminated by PAHs and other coal tar compounds. Nine of the 12 compounds and a coal tar mixture (SRM 1597A) activated group IVC PLA(2) in HCAECs, and activation of this enzyme was associated with histone fragmentation and poly (ADP) ribose polymerase (PARP) cleavage. Genetic silencing of group IVC PLA(2) inhibited both (3)H-fatty acid release and histone fragmentation by PAHs and SRM 1597A, indicating that individual PAHs and a coal tar mixture induce apoptosis of HCAECs via a mechanism that involves group IVC PLA(2). Western blot analysis of aortas isolated from feral mice (Peromyscus leucopus) inhabiting the Superfund site showed increased PARP and caspase-3 cleavage when compared to reference mice. These data suggest that PAHs induce apoptosis of HCAECs via activation of group IVC PLA(2). PMID:21132278

  5. Subway construction activity influence on polycyclic aromatic hydrocarbons in fine particles: Comparison with a background mountainous site

    NASA Astrophysics Data System (ADS)

    Kong, Shaofei; Li, Xuxu; Li, Qi; Yin, Yan; Li, Li; Chen, Kui; Liu, Dantong; Yuan, Liang; Pang, Xiaobing

    2015-07-01

    Intensive construction activities worsened the surrounding atmospheric environment in China. Eighteen polycyclic aromatic hydrocarbons (PAHs) in fine particles (PM2.5) were collected at a subway construction site (SC) of Nanjing and compared with a regional background mountainous site (BM) to examine the influence of anthropogenic activities on concentrations, sources and health risks of PAHs. Average PAH concentrations at SC were higher than BM at a factor of about 5.9. All PAH species at SC were higher than BM, with the SC/BM ratios ranging from 1.3 (NaP) to 10.3 (BaP). PAH profiles differed for the two sites. The SC site had higher mass fractions of PAHs from coal combustion and vehicle emission, while the BM site held higher mass percentages of PAHs from long-range transported wood combustion and industrial activities. Lower temperature at BM may lead to the higher mass percentages of low ring PAHs. Coal combustion, traffic emissions and biomass burning were the common sources for PAHs at both SC and BM. Construction workers were exposed to higher BaPeq concentrations, nearly ten times of the background site and their lifetime cancer risk reached to 0.6 per 1,000,000 exposed worker, owing to the influence of coal combustion, vehicle emission and industrial activities at the surroundings of SC.

  6. The Luminous Polycyclic Aromatic Hydrocarbon Emission Features: Applications to High Redshift Galaxies and Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Shipley, Heath V.

    2016-01-01

    For decades, significant work has been applied to calibrating emission from the ultra-violet, nebular emission lines, far-infrared, X-ray and radio as tracers of the star-formation rate (SFR) in distant galaxies. Understanding the exact rate of star-formation and how it evolves with time and galaxy mass has deep implications for how galaxies form. The co-evolution of star-formation and supermassive black hole (SMBH) accretion is one of the key problems in galaxy formation theory. But, many of these SFR indicators are influenced by SMBH accretion in galaxies and result in unreliable SFRs. Utilizing the luminous polycyclic aromatic hydrocarbon (PAH) emission features, I provide a new robust SFR calibration using the luminosity emitted from the PAHs at 6.2μm, 7.7μm and 11.3μm to solve this. The PAH features emit strongly in the mid-infrared (mid-IR; 5-25μm) mitigating dust extinction, containing on average 5-10% of the total IR luminosity in galaxies. I use a sample of 105 star-forming galaxies covering a range of total IR luminosity, LIR = L(8-1000μm) = 109 - 1012 L⊙ and redshift 0 < z < 0.4, with mid-IR spectroscopy from the Spitzer Infrared Spectrograph (IRS), and data covering other SFR indicators (Hα emission and rest-frame 24μm continuum emission). The PAH luminosity correlates linearly with the SFR as measured by the Hα luminosity (corrected for attenuation using the mono-chromatic rest-frame 24μm emission), with a tight scatter of <0.15 dex. The scatter is comparable to that between SFRs derived from the Paα and dust-corrected Hα emission lines. We present a case study in advance of JWST, which will be capable of measuring SFRs (from 8μm rest-frame photometry, i.e. PAHs) in distant galaxies (z ≤ 2) with JWST/MIRI to SFRs as low as ~10 M⊙yr-1, because the PAH features are so bright. We use Spitzer/IRS observations of PAH features in lensed star-forming galaxies at 1 < z < 3 to demonstrate the utility of the PAHs to derive SFRs that agree with

  7. A critical evaluation of magnetic activated carbon's potential for the remediation of sediment impacted by polycyclic aromatic hydrocarbons.

    PubMed

    Han, Zhantao; Sani, Badruddeen; Akkanen, Jarkko; Abel, Sebastian; Nybom, Inna; Karapanagioti, Hrissi K; Werner, David

    2015-04-01

    Addition of activated carbon (AC) or biochar (BC) to sediment to reduce the chemical and biological availability of organic contaminants is a promising in-situ remediation technology. But concerns about leaving the adsorbed pollutants in place motivate research into sorbent recovery methods. This study explores the use of magnetic sorbents. A coal-based magnetic activated carbon (MAC) was identified as the strongest of four AC and BC derived magnetic sorbents for polycyclic aromatic hydrocarbons (PAHs) remediation. An 8.1% MAC amendment (w/w, equal to 5% AC content) was found to be as effective as 5% (w/w) pristine AC in reducing aqueous PAHs within three months by 98%. MAC recovery from sediment after three months was 77%, and incomplete MAC recovery had both, positive and negative effects. A slight rebound of aqueous PAH concentrations was observed following the MAC recovery, but aqueous PAH concentrations then dropped again after six months, likely due to the presence of the 23% unrecovered MAC. On the other hand, the 77% recovery of the 8.1% MAC dose was insufficient to reduce ecotoxic effects of fine grained AC or MAC amendment on the egestion rate, growth and reproduction of the AC sensitive species Lumbriculus variegatus.

  8. The mechanism of action of dipeptidyl aminopeptidase. Inhibition by amino acid derivatives and amines; activation by aromatic compounds.

    PubMed

    Metrione, R M; MacGeorge, N L

    1975-12-01

    A variety of amino acid and peptide amides have been shown to be inhibitors of dipeptidyl aminopeptidase. Among these compounds derivatives of strongly hydrophobic amino acids are the strongest inhibitors (Phe-NH2, Ki = 1.0 +/- 0.2 mM), while amides of basic amino acids were somewhat less effective (Lys-NH2, Ki = 36 +/- 3 mM). Short chain amino acid amides are notably weaker inhibitors (Gly-NH2, Ki = 293 +/- 50 mM). The interaction of the side chains of compounds with the enzyme appears to be at a site other than that at which the side chain of the amino-penultimate residue of the substrate interacts since the specificity of binding is different. Primary amines have been shown to inhibit, e.g., butylamine, Ki = 340 +/- 40 mM, and aromatic compounds have been shown to stimulate activity toward Gly-Gly-NH2 and Gly-Gly-OEt (phenol, 35% stimulation of activity at a 1:1 molar ratio with the substrate). The data suggest that inhibition involves binding at the site occupied by the free alpha-amino group and the N-terminal amino acid.

  9. Polycyclic aromatic hydrocarbon-induced CYP1B1 activity is suppressed by perillyl alcohol in MCF-7 cells

    SciTech Connect

    Chan, Nelson L.S.; Wang Huan; Wang Yun; Leung, H.Y.; Leung, Lai K. . E-mail: laikleung@yahoo.com

    2006-06-01

    Perillyl alcohol (POH) is a dietary monoterpene with potential applications in chemoprevention and chemotherapy. Although clinical trials are under way, POH's physiological and pharmacological properties are still unclear. In the present study, the effect of POH on polycyclic aromatic hydrocarbon (PAH)-induced genotoxicity, and the related expression were examined in MCF-7 cells. Exposure to environmental toxicant increases the risk of cancer. Many of these compounds are pro-carcinogens and are biotransformed into their ultimate genotoxic structures by xenobiotic metabolizing enzymes. CYP1A1 and 1B1 are enzymes that catalyze the biotransformation of dimethylbenz[a]anthracene (DMBA). Our data revealed that 0.5 {mu}M of POH was effective in blocking DMBA-DNA binding. Ethoxyresorufin-O-deethylase (EROD) assay indicated that the administration of POH inhibited the DMBA-induced enzyme activity in MCF-7 cells. Enzyme kinetic analysis revealed that POH inhibited CYP1B1 but not CYP1A1 activity. Quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) assay also demonstrated that the monoterpene reduced CYP1B1 mRNA abundance induced by DMBA. The present study illustrated that POH might inhibit and downregulate CYP1B1, which could protect against PAH-induced carcinogenesis.

  10. Spectral Response and Diagnostics of Biological Activity of Hydroxyl-Containing Aromatic Compounds

    NASA Astrophysics Data System (ADS)

    Tolstorozhev, G. B.; Mayer, G. V.; Bel'kov, M. V.; Shadyro, O. I.

    2016-08-01

    Using IR Fourier spectra and employing quantum-chemical calculations of electronic structure, spectra, and proton-acceptor properties, synthetic derivatives of aminophenol exhibiting biological activity in the suppression of herpes, influenza, and HIV viruses have been investigated from a new perspective, with the aim of establishing the spectral response of biological activity of the molecules. It has been experimentally established that the participation of the aminophenol hydroxyl group in intramolecular hydrogen bonds is characteristic of structures with antiviral properties. A quantum-chemical calculation of the proton-acceptor ability of the investigated aminophenol derivatives has shown that biologically active structures are characterized by a high proton-acceptor ability of oxygen of the hydroxyl group. A correlation that has been obtained among the formation of an intramolecular hydrogen bond, high proton-acceptor ability, and antiviral activity of substituted aminophenols enables us to predict the pharmacological properties of new medical preparations of the given class of compounds.

  11. Aromatic graphene

    NASA Astrophysics Data System (ADS)

    Das, D. K.; Sahoo, S.

    2016-04-01

    In recent years graphene attracts the scientific and engineering communities due to its outstanding electronic, thermal, mechanical and optical properties and many potential applications. Recently, Popov et al. [1] have studied the properties of graphene and proved that it is aromatic but without fragrance. In this paper, we present a theory to prepare graphene with fragrance. This can be used as scented pencils, perfumes, room and car fresheners, cosmetics and many other useful household substances.

  12. Dehalogenation of aromatics by nucleophilic aromatic substitution.

    PubMed

    Sadowsky, Daniel; McNeill, Kristopher; Cramer, Christopher J

    2014-09-16

    Nucleophilic aromatic substitution has been implicated as a mechanism for both the biotic and abiotic hydrodehalogenation of aromatics. Two mechanisms for the aqueous dehalogenation of aromatics involving nucleophilic aromatic substitution with hydride as a nucleophile are investigated using a validated density functional and continuum solvation protocol. For chlorinated and brominated aromatics, nucleophilic addition ortho to carbon-halogen bonds via an anionic intermediate is predicted to be the preferred mechanism in the majority of cases, while concerted substitution is predicted to be preferred for most fluorinated aromatics. Nucleophilic aromatic substitution reactions with the hydroxide and hydrosulfide anions as nucleophiles are also investigated and compared.

  13. New aromatic activated dihalides and bisphenol monomers for the preparation of novel poly(arylene ethers)

    NASA Technical Reports Server (NTRS)

    Wolfe, James F.

    1993-01-01

    The goal of this research program was to synthesize a series of unique monomers of type I to be utilized at NASA-Langley in the preparation of new poly(arylene ether ketones), poly(arylene ether ketosulfones), and poly(arylene ether ketophosphine oxides). These A-A and A-B monomer systems, which possess activated aryl halide and/or phenolic end groups, are accessible via condensation reactions of appropriately substituted aryl acetonitrile carbanions with activated aryl dihalides followed by oxidative decyanation.

  14. Polyimidazoles Via Aromatic Nucleophilic Displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W.; Hergenrother, Paul M.

    1990-01-01

    Experiments show variety of polyimidazoles prepared by aromatic nucleophilic displacement, from reactions of bisphenol imidazoles with activated difluoro compounds. Polyimidazoles have good mechanical properties making them suitable for use as films, moldings, and adhesives.

  15. Prenatal Polycyclic Aromatic Hydrocarbon, Adiposity, Peroxisome Proliferator-Activated Receptor (PPAR) γ Methylation in Offspring, Grand-Offspring Mice

    PubMed Central

    Yan, Zhonghai; Zhang, Hanjie; Maher, Christina; Arteaga-Solis, Emilio; Champagne, Frances A.; Wu, Licheng; McDonald, Jacob D.; Yan, Beizhan; Schwartz, Gary J.; Miller, Rachel L.

    2014-01-01

    Rationale Greater levels of prenatal exposure to polycyclic aromatic hydrocarbon (PAH) have been associated with childhood obesity in epidemiological studies. However, the underlying mechanisms are unclear. Objectives We hypothesized that prenatal PAH over-exposure during gestation would lead to weight gain and increased fat mass in offspring and grand-offspring mice. Further, we hypothesized that altered adipose gene expression and DNA methylation in genes important to adipocyte differentiation would be affected. Materials and Methods Pregnant dams were exposed to a nebulized PAH mixture versus negative control aerosol 5 days a week, for 3 weeks. Body weight was recorded from postnatal day (PND) 21 through PND60. Body composition, adipose cell size, gene expression of peroxisome proliferator-activated receptor (PPAR) γ, CCAAT/enhancer-binding proteins (C/EBP) α, cyclooxygenase (Cox)-2, fatty acid synthase (FAS) and adiponectin, and DNA methylation of PPAR γ, were assayed in both the offspring and grand-offspring adipose tissue. Findings Offspring of dams exposed to greater PAH during gestation had increased weight, fat mass, as well as higher gene expression of PPAR γ, C/EBP α, Cox2, FAS and adiponectin and lower DNA methylation of PPAR γ. Similar differences in phenotype and DNA methylation extended through the grand-offspring mice. Conclusions Greater prenatal PAH exposure was associated with increased weight, fat mass, adipose gene expression and epigenetic changes in progeny. PMID:25347678

  16. Purification of Pseudomonas putida acyl coenzyme A ligase active with a range of aliphatic and aromatic substrates.

    PubMed Central

    Fernández-Valverde, M; Reglero, A; Martinez-Blanco, H; Luengo, J M

    1993-01-01

    Acyl coenzyme A (acyl-CoA) ligase (acyl-CoA synthetase [ACoAS]) from Pseudomonas putida U was purified to homogeneity (252-fold) after this bacterium was grown in a chemically defined medium containing octanoic acid as the sole carbon source. The enzyme, which has a mass of 67 kDa, showed maximal activity at 40 degrees C in 10 mM K2PO4H-NaPO4H2 buffer (pH 7.0) containing 20% (wt/vol) glycerol. Under these conditions, ACoAS showed hyperbolic behavior against acetate, CoA, and ATP; the Kms calculated for these substrates were 4.0, 0.7, and 5.2 mM, respectively. Acyl-CoA ligase recognizes several aliphatic molecules (acetic, propionic, butyric, valeric, hexanoic, heptanoic, and octanoic acids) as substrates, as well as some aromatic compounds (phenylacetic and phenoxyacetic acids). The broad substrate specificity of ACoAS from P. putida was confirmed by coupling it with acyl-CoA:6-aminopenicillanic acid acyltransferase from Penicillium chrysogenum to study the formation of several penicillins. Images PMID:8476289

  17. Electrochemically enhanced removal of polycyclic aromatic basic dyes from dilute aqueous solutions by activated carbon cloth electrodes.

    PubMed

    Bayram, Edip; Ayranci, Erol

    2010-08-15

    Open-circuit (OC) adsorption and electrosorption behaviors of three polycyclic aromatic dyes from dilute aqueous solutions onto activated carbon cloth (ACC) were investigated. The selected dyes were crystal violet (BB-3), basic blue7 (BB-7), and basic blue11 (BB-11). OC adsorption and electrosorption processes were monitored by in situ UV-visible spectrophotometry. Electrosorption was carried out by polarization of an ACC electrode, galvanostatically. Considerable enhancements in removal capacity and duration of the dyes were achieved upon polarization of ACC. Kinetic data for OC adsorption and electrosorption were successfully treated according to pseudo-first-order law, and rate constants were determined. Adsorption isotherms were derived, and the data were treated according to Langmuir and Freundlich equations. Both the rate and extent of adsorption and electrosorption of dyes were found to increase in the order of BB-7 < BB-11 < BB-3. This order was discussed in terms of correlation between sizes of dye species and of ACC pores. Electrodesorption experiments were carried out to explore possibilities of regeneration of ACC. PMID:20704233

  18. Bioassay of polycyclic aromatic hydrocarbons

    SciTech Connect

    Van Kirk, E.A.

    1980-08-01

    A positive relationship was found between the photodynamic activity of 24 polycyclic aromatic hydrocarbons versus published results on the mutagenicity, carcinogenicity, and initiation of unscheduled DNA synthesis. Metabolic activation of benzo(a)pyrene resulted in detection of increased mutagenesis in Paramecium tetraurelia as found also in the Ames Salmonella assay. The utility of P. tetraurelia as a biological detector of hazardous polycyclic aromatic hydrocarbons is discussed.

  19. Anti-plasmodial and insecticidal activities of the essential oils of aromatic plants growing in the Mediterranean area

    PubMed Central

    2012-01-01

    Background Sardinia is a Mediterranean area endemic for malaria up to the last century. During a screening study to evaluate the anti-plasmodial activity of some aromatic plants traditionally used in Sardinia, Myrtus communis (myrtle, Myrtaceae), Satureja thymbra (savory, Lamiaceae), and Thymus herba-barona (caraway thyme, Lamiaceae) were collected in three vegetative periods: before, during and after flowering. Methods The essential oils were obtained by steam distillation, fractionated by silica gel column chromatography and analysed by GC-FID-MS. Total oil and three main fractions were tested on D10 and W2 strains of Plasmodium falciparum in vitro. Larvicidal and adulticidal activities were tested on Anopheles gambiae susceptible strains. Results The essential oil of savory, rich in thymol, was the most effective against P. falciparum with an inhibitory activity independent from the time of collection (IC50 17–26 μg/ml on D10 and 9–11 μg/ml on W2). Upon fractionation, fraction 1 was enriched in mono-sesquiterpenoid hydrocarbons; fraction 2 in thymol (73-83%); and fraction 3 contained thymol, carvacrol and terpinen-4-ol, with a different composition depending on the time of collection. Thymol-enriched fractions were the most active on both strains (IC50 20–22 μg/ml on D10 and 8–10 μg/ml on W2) and thymol was confirmed as mainly responsible for this activity (IC50 19.7± 3.0 and 10.6 ± 2.0 μg/ml on D10 and W2, respectively). The essential oil of S. thymbra L. showed also larvicidal and adulticidal activities. The larvicidal activity, expressed as LC50, was 0.15 ± 0.002; 0.21 ± 0.13; and 0.15 ± 0.09 μg/ml (mean ± sd) depending on the time of collection: before, during and after flowering, respectively. Conclusions This study provides evidence for the use of essential oils for treating malaria and fighting the vector at both the larval and adult stages. These findings open the possibility for further investigation aimed at

  20. Effect of cyclic aromatics on sodium active transport in frog skin

    SciTech Connect

    Blankemeyer, J.T.; Bowerman, M.C. )

    1993-01-01

    A modified glass Ussing-chamber was used to mount the skin. The electrical potential difference (PD) was measured by two 3% agar-frog Ringer's bridges. Current (i.e. short-circuit current, or ISC) was passed by Ag-AgCl electrodes placed so that current density was uniform across the skin. Ringer's solution, bathing each side of the frog skin, was stirred and aerated by gas-lift pumps. The effect of toxicants on the ISC was determined by using the 15 min prior to toxicant administration as a control period, then calculating the change in ISC during the toxicant period as a percent of the control ISC. Phenol and benzene are components of crude oil and crude oil waste. These hydrocarbons and phenanthrene were tested for their effect on frog skin. The results show that the effect of organics on sodium active transport of an epithelium is to alter the active transport of sodium ions. 5 refs., 3 figs., 1 tab.

  1. Oxidation of polycyclic aromatic hydrocarbons using Bacillus subtilis CotA with high laccase activity and copper independence.

    PubMed

    Zeng, Jun; Zhu, Qinghe; Wu, Yucheng; Lin, Xiangui

    2016-04-01

    Bacterial laccase CueO from Escherichia coli can oxidize polycyclic aromatic hydrocarbons (PAHs); however, its application in the remediation of PAH-contaminated soil mainly suffers from a low oxidation rate and copper dependence. It was reported that a laccase with a higher redox potential tended to have a higher oxidation rate; thus, the present study investigated the oxidation of PAHs using another bacterial laccase CotA from Bacillus subtilis with a higher redox potential (525 mV) than CueO (440 mV). Recombinant CotA was overexpressed in E. coli and partially purified, exhibiting a higher laccase-specific activity than CueO over a broad pH and temperature range. CotA exhibited moderate thermostability at high temperatures. CotA oxidized PAHs in the absence of exogenous copper. Thereby, secondary heavy metal pollution can be avoided, another advantage of CotA over CueO. Moreover, this study also evaluated some unexplained phenomena in our previous study. It was observed that the oxidation of PAHs with bacterial laccases can be promoted by copper. The partially purified bacterial laccase oxidized only two of the 15 tested PAHs, i.e., anthracene and benzo[a]pyrene, indicating the presence of natural redox mediators in crude cell extracts. Overall, the recombinant CotA oxidizes PAHs with high laccase activity and copper independence, indicating that CotA is a better candidate for the remediation of PAHs than CueO. Besides, the findings here provide a better understanding of the oxidation of PAHs using bacterial laccases.

  2. Phytochemical profiles and antimicrobial activity of aromatic Malaysian herb extracts against food-borne pathogenic and food spoilage microorganisms.

    PubMed

    Aziman, Nurain; Abdullah, Noriham; Noor, Zainon Mohd; Kamarudin, Wan Saidatul Syida Wan; Zulkifli, Khairusy Syakirah

    2014-04-01

    Preliminary phytochemical and flavonoid compounds of aqueous and ethanolic extracts of 6 aromatic Malaysian herbs were screened and quantified using Reverse-Phase High Performance Liquid Chromatography (RP-HPLC). The herbal extracts were tested for their antimicrobial activity against 10 food-borne pathogenic and food spoilage microorganisms using disk diffusion assay. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC)/minimum fungicidal concentration (MFC) of herbal extracts were determined. In the phytochemical screening process, both aqueous and ethanolic extracts of P. hydropiper exhibited presence of all 7 tested phytochemical compounds. Among all herbal extracts, the aqueous P. hydropiper and E. elatior extracts demonstrated the highest antibacterial activity against 7 tested Gram-positive and Gram-negative bacteria with diameter ranging from 7.0 to 18.5 mm and 6.5 to 19 mm, respectively. The MIC values for aqueous and ethanolic extracts ranged from 18.75 to 175 mg/mL and 0.391 to 200 mg/mL, respectively while the MBC/MFC values for aqueous and ethanolic extracts ranged from 25 to 200 mg/mL and 3.125 to 50 mg/mL, respectively. Major types of bioactive compounds in aqueous P. hydropiper and E. elatior extracts were identified using RP-HPLC instrument. Flavonoids found in these plants were epi-catechin, quercetin, and kaempferol. The ability of aqueous Persicaria hydropiper (L.) H. Gross and Etlingera elatior (Jack) R.M. Sm. extracts to inhibit the growth of bacteria is an indication of its broad spectrum antimicrobial potential. Hence these herbal extracts may be used as natural preservative to improve the safety and shelf-life of food and pharmaceutical products.

  3. Evaluation of the mutagenic activity of chrysin, a flavonoid inhibitor of the aromatization process.

    PubMed

    Oliveira, G A R; Ferraz, E R A; Souza, A O; Lourenço, R A; Oliveira, D P; Dorta, D J

    2012-01-01

    Chrysin is one of the natural flavonoids present in plants, and large amounts are present in honey and propolis. In addition to anticancer, antioxidation, and anti-inflammatory activities, chrysin has also been reported to be an inhibitor of aromatase, an enzyme converting testosterone into estrogen. The present study evaluated the mutagenicity of this flavonoid using micronucleus (MN) with HepG2 cells and Salmonella. Cell survival after exposure to different concentrations of chrysin was also determined using sulforhodamine B (SRB) colorimetric assay in HepG2 cells and the influence of this flavonoid on growth of cells in relation to the cell cycle and apoptosis. The MN test showed that from 1 to 15 μM of this flavonoid mutagenic activity was noted in HepG2 cells. The Salmonella assay demonstrated a positive response to the TA100 Salmonella strain in the presence or absence of S9, suggesting that this compound acted on DNA, inducing base pair substitution before or after metabolism via cytochrome P-450. The SRB assay illustrated that chrysin promoted growth inhibition of HepG2 cells in both periods studied (24 and 48 h). After 24 h of exposure it was noted that the most significant results were obtained with a concentration of 50 μM, resulting in 83% inhibition and SubG0 percentage of 12%. After 48 h of incubation cell proliferation inhibition rates (97% at 50 μM) were significantly higher. Our results showed that chrysin is a mutagenic and cytotoxic compound in cultured human HepG2 cells and Salmonella typhimurium. Although it is widely accepted that flavonoids are substances beneficial to health, one must evaluate the risk versus benefit relationship and concentrations of these substances to which an individual may be exposed.

  4. Induction of biotransformation in the liver of Eel (Anguilla anguilla L. ) by sublethal exposure to dinitro-o-cresol: An ultrastructural and biochemical study

    SciTech Connect

    Braunbeck, T.; Voelkl, A. )

    1991-04-01

    Structural and functional alterations in hepatocytes of the European eel, Anguilla anguilla, following a 4-week-exposure to 5, 50, and 250 micrograms/liter dinitro-o-cresol (DNOC) were investigated by means of electron microscopy and biochemistry and compared to liver pathology in eels exposed to the chemical spill into the Rhine river at Basle in November 1986. Whereas phenological parameters (growth, condition factor) are unaffected, ultrastructural and biochemical alterations are detectable at greater than or equal to 50 and 5 micrograms/liter DNOC, respectively. Structural modifications include: rounding-up of the nuclei; fractionation and reduction of the rough endoplasmic reticulum; proliferation of the smooth endoplasmic reticulum (SER), mitochondria, peroxisomes, and lysosomes; bundles of rod-shaped SER profiles; annulate lamellae; membrane whorls within mitochondria; crystallization of the peroxisomal matrix and glycogen bodies; glycogen depletion and lipid augmentation. Structural changes can be correlated to an increase in hepatic lipid and protein contents as well as stimulation of mitochondrial (cytochrome c oxidase), peroxisomal (catalase, allantoinase, uricase), lysosomal (arylsulfatase), and microsomal (esterase) enzymes. An increase in NADPH-cytochrome c reductase and cytochrome P450 as well as UDP-glucuronyltransferase and arylsulfotransferase activities in the microsomal fraction document an induction of hepatic biotransformation as a functional correlate to SER proliferation. Maximum inducibility of biotransformation enzymes at 50 micrograms/liter indicates a biphasic, concentration-dependent reaction of eel liver. Comparison of DNOC-induced effects with liver pathology in eel exposed to the chemical spill in 1986 reveals striking similarities so that DNOC may not be excluded as a possible factor in the fish kill in the Rhine river.

  5. Treatment of soil eluate containing nitro aromatic compounds by adsorption on activated coke (AC).

    PubMed

    Zhang, Yiping; Jiang, Zhenming; Zhao, Quanlin; Zhang, Zhenzhong; Su, Hongping; Gao, Xuewen; Ye, Zhengfang

    2016-01-01

    Soil washing is a kind of physical method to remove organic matters from contaminated soil. However, its eluate after washing may result in secondary pollution to the environment. In this study, activated coke (AC) was used to remove organic pollutants from contaminated soil eluate. The effect of temperature, initial chemical oxygen demand (COD) and AC dosage on COD removal efficiency was investigated. The results showed that the organic matter can be removed in the eluate because the COD dropped a lot. When the AC dosage was 20 g·L(-1), 88.92% of COD decreased after 480 min of adsorption at 50 °C. The process of adsorption can be described by the Redlich-Peterson isotherm. The adsorption was spontaneous and endothermic. The pseudo-second-order model can be used to describe the adsorption process. After adsorption, the acute toxicity of the eluate was reduced by 76%, and the water qualities were in agreement with Chinese discharge standard GB 14470.1-2002, which means the eluate could be discharged to the environment. PMID:27003071

  6. Treatment of soil eluate containing nitro aromatic compounds by adsorption on activated coke (AC).

    PubMed

    Zhang, Yiping; Jiang, Zhenming; Zhao, Quanlin; Zhang, Zhenzhong; Su, Hongping; Gao, Xuewen; Ye, Zhengfang

    2016-01-01

    Soil washing is a kind of physical method to remove organic matters from contaminated soil. However, its eluate after washing may result in secondary pollution to the environment. In this study, activated coke (AC) was used to remove organic pollutants from contaminated soil eluate. The effect of temperature, initial chemical oxygen demand (COD) and AC dosage on COD removal efficiency was investigated. The results showed that the organic matter can be removed in the eluate because the COD dropped a lot. When the AC dosage was 20 g·L(-1), 88.92% of COD decreased after 480 min of adsorption at 50 °C. The process of adsorption can be described by the Redlich-Peterson isotherm. The adsorption was spontaneous and endothermic. The pseudo-second-order model can be used to describe the adsorption process. After adsorption, the acute toxicity of the eluate was reduced by 76%, and the water qualities were in agreement with Chinese discharge standard GB 14470.1-2002, which means the eluate could be discharged to the environment.

  7. Visible-Light-Induced Olefin Activation Using 3D Aromatic Boron-Rich Cluster Photooxidants.

    PubMed

    Messina, Marco S; Axtell, Jonathan C; Wang, Yiqun; Chong, Paul; Wixtrom, Alex I; Kirlikovali, Kent O; Upton, Brianna M; Hunter, Bryan M; Shafaat, Oliver S; Khan, Saeed I; Winkler, Jay R; Gray, Harry B; Alexandrova, Anastassia N; Maynard, Heather D; Spokoyny, Alexander M

    2016-06-01

    We report a discovery that perfunctionalized icosahedral dodecaborate clusters of the type B12(OCH2Ar)12 (Ar = Ph or C6F5) can undergo photo-excitation with visible light, leading to a new class of metal-free photooxidants. Excitation in these species occurs as a result of the charge transfer between low-lying orbitals located on the benzyl substituents and an unoccupied orbital delocalized throughout the boron cluster core. Here we show how these species, photo-excited with a benchtop blue LED source, can exhibit excited-state reduction potentials as high as 3 V and can participate in electron-transfer processes with a broad range of styrene monomers, initiating their polymerization. Initiation is observed in cases of both electron-rich and electron-deficient styrene monomers at cluster loadings as low as 0.005 mol%. Furthermore, photo-excitation of B12(OCH2C6F5)12 in the presence of a less activated olefin such as isobutylene results in the production of highly branched poly(isobutylene). This work introduces a new class of air-stable, metal-free photo-redox reagents capable of mediating chemical transformations. PMID:27186856

  8. Halogen Bonding and Chalcogen Bonding in 4,7-Dibromo-5,6-dinitro-2,1,3-benzothiadiazole.

    PubMed

    Pavan, Mysore S; Jana, Ajay Kumar; Natarajan, S; Guru Row, Tayur N

    2015-08-27

    An organic solid, 4,7-dibromo-5,6-dinitro-2,1,3-benzothiadiazole, has been designed to serve as an illustrative example to quantitatively evaluate the relative merits of halogen and chalcogen bonding in terms of charge density features. The compound displays two polymorphic modifications, one crystallizing in a non-centrosymmetric space group (Z' = 1) and the other in a centrosymmetric space group with two molecules in the asymmetric unit (Z' = 2). Topological analysis based on QTAIM clearly brings out the dominance of the chalcogen bond over the halogen bond along with an indication that halogen bonds are more directional compared to chalcogen bonds. The cohesive energies calculated with the absence of both strong and weak hydrogen bonds as well as stacking interaction are indicative of the stabilities associated with the polymorphic forms.

  9. Interaction Between Cytochrome c and the Hapten 2,4-Dinitro-fluorobenzene by Electrospray Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Wu, Bo; Chu, Yan-qiu; Dai, Zhao-yun; Ding, Chuan-fan

    2008-06-01

    Allergic contact dermatitis is a delayed hypersensitivity reaction, which results from skin exposure to low molecular weight chemicals such as haptens. To clarify the pathogenic mechanism, electrospray ionization mass spectrometry (ESI-MS) and hydrogen/deuterium (H/D) exchange, as well as UV spectroscopy, were applied to determine the interaction between the model protein cytochrome c (cyt c) and the hapten 2,4-dinitro-fluorobenzene (DNFB). The ESI-MS results demonstrate that the conformation of cyt c can change from native folded state into partially unfolded state with the increase of DNFB. The equilibrium state H/D exchange followed by ESI-MS further confirms the above results. UV spectroscopy indicates that the strong-field coordination between iron of heme (prosthetic group) and His18 or Met80 of cyt c is not obviously affected by the hapten.

  10. 1H NMR analysis of complexation of hydrotropic agents nicotinamide and caffeine with aromatic biologically active molecules in aqueous solution

    NASA Astrophysics Data System (ADS)

    Lantushenko, Anastasia O.; Mukhina, Yulia V.; Veselkov, Kyrill A.; Davies, David B.; Veselkov, Alexei N.

    2004-07-01

    NMR spectroscopy has been used to elucidate the molecular mechanism of solubilization action of hydrotropic agents nicotinamide (NA) and caffeine (CAF). Hetero-association of NA with riboflavine-mononucleotide (FMN) and CAF with low soluble in aqueous solution synthetic analogue of antibiotic actinomycin D, actinocyl-bis-(3-dimethylaminopropyl) amine (Actill), has been investigated by 500 MHz 1H NMR spectroscopy. Concentration and temperature dependences of proton chemical shifts have been analysed in terms of a statistical-thermodynamic model of indefinite self- and heteroassociation of aromatic molecules. The obtained results enable to conclude that NA-FMN and CAF-Actill intermolecular complexes are mainly stabilized by the stacking interactions of the aromatic chromophores. Hetero-association of the investigated molecules plays an important role in solubilization of aromatic drugs by hydrotropic agents nicotinamide and caffeine.

  11. Manganese peroxidase mRNA and enzyme activity levels during bioremediation of polycyclic aromatic hydrocarbon-contaminated soil with Phanerochaete chrysosporium

    SciTech Connect

    Bogan, B.W.; Schoenike, B.; Lamar, R.T.; Cullen, D.

    1996-07-01

    mRNA extraction from soil and quantitation by competitive reverse transcription-PCR were combined to study the expression of three manganese peroxidase (MnP) genes during removal of polycyclic aromatic hydrocarbons from cultures of Phanerochaete chrysosporium grown in presterilized soil. Periods of high mnp transcript levels and extractable MnP enzyme activity were temporally correlated, although separated by a short (1- to 2-day) lag period. This time frame also coincided with maximal rates of fluorene oxidation and chrysene disappearance in soil cultures, supporting the hypothesis that high ionization potential polycyclic aromatic hydrocarbons are oxidized in soil via MnP-dependent mechanisms. The patterns of transcript abundance over time in soil-grown P. chrysosporium were similar for all three of the mnp mRNAs studied, indicating that transcription of this gene family may be coordinately regulated under these growth conditions. 47 refs., 6 figs., 1 tab.

  12. Fate of aromatic hydrocarbons in Italian municipal wastewater systems: an overview of wastewater treatment using conventional activated-sludge processes (CASP) and membrane bioreactors (MBRs).

    PubMed

    Fatone, Francesco; Di Fabio, Silvia; Bolzonella, David; Cecchi, Franco

    2011-01-01

    We studied the occurrence, removal, and fate of 16 polycyclic aromatic hydrocarbons (PAHs) and 23 volatile organic compounds (VOCs) in Italian municipal wastewater treatment systems in terms of their common contents and forms, and their apparent and actual removal in both conventional activated-sludge processes (CASP) and membrane bioreactors (MBRs). We studied five representative full-scale CASP treatment plants (design capacities of 12,000 to 700,000 population-equivalent), three of which included MBR systems (one full-scale and two pilot-scale) operating in parallel with the conventional systems. We studied the solid-liquid partitioning and fates of these substances using both conventional samples and a novel membrane-equipped automatic sampler. Among the VOCs, toluene, ethylbenzene, xylenes, styrene, 1,2,4-trimethylbenzene, and 4-chlorotoluene were ubiquitous, whereas naphthalene, acenaphthene, fluorene, and phenanthrene were the most common PAHs. Both PAHs and aromatic VOCs had removal efficiencies of 40-60% in the headworks, even in plants without primary sedimentation. Mainly due to volatilization, aromatic VOCs had comparable removal efficiencies in CASP and MBRs, even for different sludge ages. MBRs did not enhance the retention of PAHs sorbed to suspended particulates compared with CASPs. On the other hand, the specific daily accumulation of PAHs in the MBR's activated sludge decreased logarithmically with increasing sludge age, indicating enhanced biodegradation of PAHs. The PAH and aromatic VOC contents in the final effluent are not a major driver for widespread municipal adoption of MBRs, but MBRs may enhance the biodegradation of PAHs and their removal from the environment.

  13. Interaction of smoking, uptake of polycyclic aromatic hydrocarbons, and cytochrome P450IA2 activity among foundry workers.

    PubMed Central

    Sherson, D; Sigsgaard, T; Overgaard, E; Loft, S; Poulsen, H E; Jongeneelen, F J

    1992-01-01

    An increased lung cancer risk has been described among foundry workers. Polycyclic aromatic hydrocarbons (PAHs) and silica are possible aetiological factors. This study describes a urinary PAH metabolite, 1-hydroxypyrene (hpU), as well as the degree of cytochrome P450IA2 activity/induction as reflected by the urinary caffeine ratio (IA2) in 45 foundry workers and 52 controls; IA2 was defined as the ratio of paraxanthine 7-demethylation products to a paraxanthine 8-hydroxylation product (1,7-dimethyluric acid). Mean exposure concentrations for foundry workers were defined by breathing zone hygienic samples (respirable dust 1.2 to 3.52 mg/m3 (93 samples)) and as total PAH (0.46 micrograms/m3) and pyrene concentrations (0.28 micrograms/m3) (six samples). Non-smoking controls and foundry workers had similar IA2 ratios (5.63, 95% confidence interval (95% CI) 4.56-6.70 and 4.40, 95% CI 3.56-5.24). The same was true for smoking controls and foundry workers (9.10, 95% CI 8.00-10.20 and 8.69, 95% CI 7.37-10.01). Both smoking groups had raised IA2 ratios compared with non-smokers (p less than 0.01). Non-smoking controls and foundry workers had similar hpU concentrations (0.16, 95% CI 0.10-0.22 and 0.11, 95% CI 0.09-0.13 mumol/mol creatinine). Smoking foundry workers had raised hpU concentrations (0.42, 95% CI 0.25-0.59) compared with smoking controls (0.26, 95% CI 0.18-0.34) (p less than 0.01). A small subgroup of smoking foundry workers with the highest exposures to both silica and PAH also had the highest hpU concentrations (0.70, 95% CI - 0.07-1.47 mumol/mol creatinine) (p less than 0.04). Increased hpU concentrations in smoking foundry workers suggest a more than additive effect from smoking and foundry exposures resulting in increased PAH uptake. Increased P450IA2 enzyme activity was only found in smokers and no additional effect of foundry exposures was seen. These data suggest that smoking as well as work related PAH exposure may be casually related to increased risk

  14. Anti-Prion Activity of a Panel of Aromatic Chemical Compounds: In Vitro and In Silico Approaches

    PubMed Central

    Ferreira, Natalia C.; Marques, Icaro A.; Conceição, Wesley A.; Macedo, Bruno; Machado, Clarice S.; Mascarello, Alessandra; Chiaradia-Delatorre, Louise Domeneghini; Yunes, Rosendo Augusto; Nunes, Ricardo José; Hughson, Andrew G.; Raymond, Lynne D.; Pascutti, Pedro G.; Caughey, Byron; Cordeiro, Yraima

    2014-01-01

    The prion protein (PrP) is implicated in the Transmissible Spongiform Encephalopathies (TSEs), which comprise a group of fatal neurodegenerative diseases affecting humans and other mammals. Conversion of cellular PrP (PrPC) into the scrapie form (PrPSc) is the hallmark of TSEs. Once formed, PrPSc aggregates and catalyzes PrPC misfolding into new PrPSc molecules. Although many compounds have been shown to inhibit the conversion process, so far there is no effective therapy for TSEs. Besides, most of the previously evaluated compounds failed in vivo due to poor pharmacokinetic profiles. In this work we propose a combined in vitro/in silico approach to screen for active anti-prion compounds presenting acceptable drugability and pharmacokinetic parameters. A diverse panel of aromatic compounds was screened in neuroblastoma cells persistently infected with PrPSc (ScN2a) for their ability to inhibit PK-resistant PrP (PrPRes) accumulation. From ∼200 compounds, 47 were effective in decreasing the accumulation of PrPRes in ScN2a cells. Pharmacokinetic and physicochemical properties were predicted in silico, allowing us to obtain estimates of relative blood brain barrier permeation and mutagenicity. MTT reduction assays showed that most of the active compounds were non cytotoxic. Compounds that cleared PrPRes from ScN2a cells, were non-toxic in the MTT assay, and presented a good pharmacokinetic profile were investigated for their ability to inhibit aggregation of an amyloidogenic PrP peptide fragment (PrP109–149). Molecular docking results provided structural models and binding affinities for the interaction between PrP and the most promising compounds. In summary, using this combined in vitro/in silico approach we have identified new small organic anti-scrapie compounds that decrease the accumulation of PrPRes in ScN2a cells, inhibit the aggregation of a PrP peptide, and possess pharmacokinetic characteristics that support their drugability. These compounds are

  15. Polycyclic Aromatic Hydrocarbon Affects Acetic Acid Production during Anaerobic Fermentation of Waste Activated Sludge by Altering Activity and Viability of Acetogen.

    PubMed

    Luo, Jingyang; Chen, Yinguang; Feng, Leiyu

    2016-07-01

    Till now, almost all the studies on anaerobic fermentation of waste activated sludge (WAS) for bioproducts generation focused on the influences of operating conditions, pretreatment methods and sludge characteristics, and few considered those of widespread persistent organic pollutants (POPs) in sludge, for example, polycyclic aromatic hydrocarbons (PAHs). Herein, phenanthrene, which was a typical PAH and widespread in WAS, was selected as a model compound to investigate its effect on WAS anaerobic fermentation for short-chain fatty acids (SCFAs) accumulation. Experimental results showed that the concentration of SCFAs derived from WAS was increased in the presence of phenanthrene during anaerobic fermentation. The yield of acetic acid which was the predominant SCFA in the fermentation reactor with the concentration of 100 mg/kg dry sludge was 1.8 fold of that in the control. Mechanism exploration revealed that the present phenanthrene mainly affected the acidification process of anaerobic fermentation and caused the shift of the microbial community to benefit the accumulation of acetic acid. Further investigation showed that both the activities of key enzymes (phosphotransacetylase and acetate kinase) involved in acetic acid production and the quantities of their corresponding encoding genes were enhanced in the presence of phenanthrene. Viability tests by determining the adenosine 5'-triphosphate content and membrane potential confirmed that the acetogens were more viable in anaerobic fermentation systems with phenanthrene, which resulted in the increased production of acetic acid. PMID:27267805

  16. Comparison of carbon-sulfur and carbon-amine bond in therapeutic drug: 4β-S-aromatic heterocyclic podophyllum derivatives display antitumor activity

    PubMed Central

    Li, Jian-Long; Zhao, Wei; Zhou, Chen; Zhang, Ya-Xuan; Li, Hong-Mei; Tang, Ya-Ling; Liang, Xin-Hua; Chen, Tao; Tang, Ya-Jie

    2015-01-01

    Herein is a first effort to systematically study the significance of carbon-sulfur (C-S) and carbon-amine (C-NH) bonds on the antitumor proliferation activity of podophyllum derivatives and their precise mechanism of apoptosis. Compared with the derivative modified by a C-NH bond, the derivative modified by a C-S bond exhibited superior antitumor activity, the inhibition activity of target proteins tubulin or Topo II, cell cycle arrest, and apoptosis induction. Antitumor mechanistic studies showed that the death receptor and the mitochondrial apoptotic pathways were simultaneously activated by the C-S bond modified aromatic heterocyclic podophyllum derivatives with a higher cellular uptake percentage of 60–90% and induction of a higher level of reactive oxygen species (ROS). Only the mitochondrial apoptotic pathway was activated by the C-NH bond modified aromatic heterocyclic podophyllum derivatives, with a lower cellular uptake percentage of 40–50%. This study provided insight into effects of the C-S and C-NH bond modification on the improvement of the antitumor activity of Podophyllum derivatives. PMID:26443888

  17. Comparison of carbon-sulfur and carbon-amine bond in therapeutic drug: 4β-S-aromatic heterocyclic podophyllum derivatives display antitumor activity.

    PubMed

    Li, Jian-Long; Zhao, Wei; Zhou, Chen; Zhang, Ya-Xuan; Li, Hong-Mei; Tang, Ya-Ling; Liang, Xin-Hua; Chen, Tao; Tang, Ya-Jie

    2015-10-07

    Herein is a first effort to systematically study the significance of carbon-sulfur (C-S) and carbon-amine (C-NH) bonds on the antitumor proliferation activity of podophyllum derivatives and their precise mechanism of apoptosis. Compared with the derivative modified by a C-NH bond, the derivative modified by a C-S bond exhibited superior antitumor activity, the inhibition activity of target proteins tubulin or Topo II, cell cycle arrest, and apoptosis induction. Antitumor mechanistic studies showed that the death receptor and the mitochondrial apoptotic pathways were simultaneously activated by the C-S bond modified aromatic heterocyclic podophyllum derivatives with a higher cellular uptake percentage of 60-90% and induction of a higher level of reactive oxygen species (ROS). Only the mitochondrial apoptotic pathway was activated by the C-NH bond modified aromatic heterocyclic podophyllum derivatives, with a lower cellular uptake percentage of 40-50%. This study provided insight into effects of the C-S and C-NH bond modification on the improvement of the antitumor activity of Podophyllum derivatives.

  18. Retinobenzoic acids. 4. Conformation of aromatic amides with retinoidal activity. Importance of trans-amide structure for the activity.

    PubMed

    Kagechika, H; Himi, T; Kawachi, E; Shudo, K

    1989-10-01

    N-Methylation of two retinoidal amide compounds, 4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)carbamoyl]benz oic acid (3, Am80) and 4-[[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2- naphthalenyl)carbonyl]amino]benzoic acid (5, Am580), resulted in the disappearance of their potent differentiation-inducing activity on human promyelocytic leukemia cell line HL-60. Studies with 1H NMR and UV spectroscopy indicated that large conformational differences exist between the active secondary amides and the inactive N-methyl amides. From a comparison of the spectroscopic results of these amides with those of stilbene derivatives, the conformations of the active amides are expected to resemble that of (E)-stilbene, whereas the inactive amides resemble the Z isomer: 3 (Am80) and 5 (Am580) have a trans-amide bond and their whole structures are elongated, while the N-methylated compounds [4 (Am90) and 6 (Am590)] have a cis-amide bond, resulting in the folding of the two benzene rings. These structures in the crystals were related to those in solution by 13C NMR spectroscopic comparison between the two phases (solid and solution).

  19. Inhibition of peripheral aromatization in baboons by an enzyme-activated aromatase inhibitor (MDL 18,962)

    SciTech Connect

    Longcope, C.; Femino, A.; Johnston, J.O.

    1988-05-01

    The peripheral aromatization ((rho)BM) of androstenedione (A) and testosterone (T) was measured before and after administration of the aromatase inhibitor 10-(2 propynyl)estr-4-ene-3,17-dione (MDL-18,962) to five mature female baboons, Papio annubis. The measurements were made by infusing (3H)androstenedione/(14C)estrone or (3H)testosterone/(14C)estradiol for 3.5 h and collecting blood samples during the infusions and all urine for 96 h from the start of the infusion. Blood samples were analyzed for radioactivity as infused and product steroids, and the data were used to calculate MCRs. An aliquot of the pooled urine was analyzed for the glucuronides of estrone and estradiol and used to calculate the (rho)BM. MDL-18,962 was administered as a pulse in polyethylene glycol-400 (1-5 ml) either iv or via gastric tube 30 min before administration of the radiolabeled steroids. Control studies were done with and without polyethylene glycol-400 administration. When MDL-18,962 was given iv at 4 mg/kg, the aromatization of A was decreased 91.8 +/- 0.9% from the control value of 1.23 +/- 0.13% to 0.11 +/- 0.01%. At the same dose, aromatization of T was decreased 82.0 +/- 7.1%, from a control value of 0.20 +/- 0.03% to 0.037 +/- 0.018%. When MDL-18,962 was given iv at doses of 0.4, 0.1, 0.04, and 0.01 mg/kg, the values for aromatization of A were 0.16 +/- 0.03%, 0.18 +/- 0.06%, 0.37 +/- 11%, and 0.65 +/- 0.09%, respectively. The administration of MDL-18,962 via gastric tube at 4 mg/kg as a pulse decreased the aromatization of A from 1.35 +/- 0.06% to 0.43 +/- 0.12%, an inhibition of 67.2 +/- 10.7%. When administered via gastric tube daily for 5 days at 4 mg/kg, the aromatization of A fell from 1.35 +/- 0.06% to 0.063 +/- 0.003%, an inhibition of 84.4 +/- 0.5%.

  20. Studies on the Simultaneous Formation of Aroma-Active and Toxicologically Relevant Vinyl Aromatics from Free Phenolic Acids during Wheat Beer Brewing.

    PubMed

    Langos, Daniel; Granvogl, Michael

    2016-03-23

    During the brewing process of wheat beer, the desired aroma-active vinyl aromatics 2-methoxy-4-vinylphenol and 4-vinylphenol as well as the undesired and toxicologically relevant styrene are formed from their respective precursors, free ferulic acid, p-coumaric acid, and cinnamic acid, deriving from the malts. Analysis of eight commercial wheat beers revealed high concentrations of 2-methoxy-4-vinylphenol and 4-vinylphenol always in parallel with high concentrations of styrene or low concentrations of the odorants in parallel with low styrene concentrations, suggesting a similar pathway. To better understand the formation of these vinyl aromatics, each process step of wheat beer brewing and the use of different strains of Saccharomyces cerevisiae were evaluated. During wort boiling, only a moderate decarboxylation of free phenolic acids and formation of desired and undesired vinyl aromatics were monitored due to the thermal treatment. In contrast, this reaction mainly occurred enzymatically catalyzed during fermentation with S. cerevisiae strain W68 with normal Pof(+) activity (phenolic off-flavor) resulting in a wheat beer eliciting the typical aroma requested by consumers due to high concentrations of 2-methoxy-4-vinylphenol (1790 μg/L) and 4-vinylphenol (937 μg/L). Unfortunately, also a high concentration of undesired styrene (28.3 μg/L) was observed. Using a special S. cerevisiae strain without Pof(+) activity resulted in a significant styrene reduction (

  1. Studies on the Simultaneous Formation of Aroma-Active and Toxicologically Relevant Vinyl Aromatics from Free Phenolic Acids during Wheat Beer Brewing.

    PubMed

    Langos, Daniel; Granvogl, Michael

    2016-03-23

    During the brewing process of wheat beer, the desired aroma-active vinyl aromatics 2-methoxy-4-vinylphenol and 4-vinylphenol as well as the undesired and toxicologically relevant styrene are formed from their respective precursors, free ferulic acid, p-coumaric acid, and cinnamic acid, deriving from the malts. Analysis of eight commercial wheat beers revealed high concentrations of 2-methoxy-4-vinylphenol and 4-vinylphenol always in parallel with high concentrations of styrene or low concentrations of the odorants in parallel with low styrene concentrations, suggesting a similar pathway. To better understand the formation of these vinyl aromatics, each process step of wheat beer brewing and the use of different strains of Saccharomyces cerevisiae were evaluated. During wort boiling, only a moderate decarboxylation of free phenolic acids and formation of desired and undesired vinyl aromatics were monitored due to the thermal treatment. In contrast, this reaction mainly occurred enzymatically catalyzed during fermentation with S. cerevisiae strain W68 with normal Pof(+) activity (phenolic off-flavor) resulting in a wheat beer eliciting the typical aroma requested by consumers due to high concentrations of 2-methoxy-4-vinylphenol (1790 μg/L) and 4-vinylphenol (937 μg/L). Unfortunately, also a high concentration of undesired styrene (28.3 μg/L) was observed. Using a special S. cerevisiae strain without Pof(+) activity resulted in a significant styrene reduction (

  2. Graphene stabilized ultra-small CuNi nanocomposite with high activity and recyclability toward catalysing the reduction of aromatic nitro-compounds

    NASA Astrophysics Data System (ADS)

    Fang, Hao; Wen, Ming; Chen, Hanxing; Wu, Qingsheng; Li, Weiying

    2015-12-01

    Nowadays, it is of great significance and a challenge to design a noble-metal-free catalyst with high activity and a long lifetime for the reduction of aromatic nitro-compounds. Here, a 2D structured nanocomposite catalyst with graphene supported CuNi alloy nanoparticles (NPs) is prepared, and is promising for meeting the requirements of green chemistry. In this graphene/CuNi nanocomposite, the ultra-small CuNi nanoparticles (~2 nm) are evenly anchored on graphene sheets, which is not only a breakthrough in the structures, but also brings about an outstanding performance in activity and stability. Combined with a precise optimization of the alloy ratios, the reaction rate constant of graphene/Cu61Ni39 reached a high level of 0.13685 s-1, with a desirable selectivity as high as 99% for various aromatic nitro-compounds. What's more, the catalyst exhibited a unprecedented long lifetime because it could be recycled over 25 times without obvious performance decay or even a morphology change. This work showed the promise and great potential of noble-metal-free catalysts in green chemistry.Nowadays, it is of great significance and a challenge to design a noble-metal-free catalyst with high activity and a long lifetime for the reduction of aromatic nitro-compounds. Here, a 2D structured nanocomposite catalyst with graphene supported CuNi alloy nanoparticles (NPs) is prepared, and is promising for meeting the requirements of green chemistry. In this graphene/CuNi nanocomposite, the ultra-small CuNi nanoparticles (~2 nm) are evenly anchored on graphene sheets, which is not only a breakthrough in the structures, but also brings about an outstanding performance in activity and stability. Combined with a precise optimization of the alloy ratios, the reaction rate constant of graphene/Cu61Ni39 reached a high level of 0.13685 s-1, with a desirable selectivity as high as 99% for various aromatic nitro-compounds. What's more, the catalyst exhibited a unprecedented long lifetime

  3. Role of cytochrome p4501 family members in the metabolic activation of polycyclic aromatic hydrocarbons in mouse epidermis.

    PubMed

    Kleiner, Heather E; Vulimiri, Suryanarayana V; Hatten, William B; Reed, Melissa J; Nebert, Daniel W; Jefcoate, Colin R; DiGiovanni, John

    2004-12-01

    Polycyclic aromatic hydrocarbons (PAHs) are known to be activated by the cytochrome P450 (P450) 1 family. However, the precise role of individual P4501 family members in PAH bioactivation remains to be fully elucidated. We therefore investigated the formation of PAH-DNA adducts in the epidermis of Cyp1a2(-/-), Cyp1b1(-/-), and Ahr(-/-) knockout mice. A panel of different PAHs was used, ranging in carcinogenic potency. Mice were treated topically on the dorsal skin with the following tritium-labeled PAHs: dibenzo[a,l]pyre-ne (DB[a,l]P), 7,12-dimethylbenz[a]anthracene (DMBA), benzo[a]pyrene (B[a]P), dibenzo[a,h]anthracene (DB[a,h]A), benzo[g]chrysene (B[g]C), and benzo[c]phenanthrene (B[c]P). At 24 h after treatment, mice (two male and two female mice per group) were sacrificed, and epidermal DNA was isolated and hydrolyzed with DNase I; subsequently, DNA adducts were quantitated by liquid scintillation counting. In the DB[a,l]P-treated mice, levels of DNA adducts were significantly lower in Cyp1a2(-/-) and Cyp1b1(-/-) mice by 57 and 46%, respectively, as compared to wild-type (WT) mice (C57BL/6 background). The levels of DB[a,l]P DNA adducts formed in Ahr(-/-) mice were 26% lower, but this was not statistically significant. The levels of DMBA-DNA adducts in Cyp1a2(-/-) mice were not different than the WT mice but were significantly lower in Cyp1b1(-/-) and Ahr(-/-) mice by 64 and 52%, respectively. DMBA-DNA adduct samples were further analyzed by HPLC following further digestion to deoxyribonucleosides. HPLC analysis of individual DMBA-DNA adducts revealed differences in the ratio of syn-DMBA-diol epoxide- to anti-DMBA-diol epoxide-derived adducts in the Ahr(-/-) and Cyp1b1(-/-) mice. The ratio of syn-/anti-derived adducts in WT mice was 0.49. This ratio was 0.23 in the Cyp1b1(-/-) mice and 0.87 in the Ahr(-/-) mice. In contrast to the results with DB[a,l]P and DMBA, the levels of B[a]P-, DB[a,h]A-, B[g]C-, and B[c]P-DNA adducts were significantly lower in Ahr

  4. [Inhibitory activity of hydrosols prepared from 18 Japanese herbs of weak aromatic flavor against filamentous formation and growth of Candida albicans].

    PubMed

    Inouye, Shigeharu; Takahashi, Miki; Abe, Shigeru

    2012-01-01

    Leaf hydrosols prepared from 18 weakly aromatic Japanese herbs used traditionally were tested on the filamentation-inhibitory activity of Candida albicans. These hydrosols were divided into two classes, A and B. The inhibitory activity of 13 hydrosols belonging to class A was markedly altered depending on the drying process of the parent herbs. On the other hand, the remaining 5 hydrosols belonging to class B showed no significant change on the composition and inhibitory activity upon drying. The change of the bioactivity was correlated with the change and concentration of the respective major constituents. Especially strong bioactivity shown by hydrosols of dried Houttuynia cordata and fresh Prunus pendula was ascribed to n-capric acid and cyanide, respectively. Eight hydrosols exhibited weak or moderate activity against the growth of C. albicans.

  5. [Inhibitory activity of hydrosols prepared from 18 Japanese herbs of weak aromatic flavor against filamentous formation and growth of Candida albicans].

    PubMed

    Inouye, Shigeharu; Takahashi, Miki; Abe, Shigeru

    2012-01-01

    Leaf hydrosols prepared from 18 weakly aromatic Japanese herbs used traditionally were tested on the filamentation-inhibitory activity of Candida albicans. These hydrosols were divided into two classes, A and B. The inhibitory activity of 13 hydrosols belonging to class A was markedly altered depending on the drying process of the parent herbs. On the other hand, the remaining 5 hydrosols belonging to class B showed no significant change on the composition and inhibitory activity upon drying. The change of the bioactivity was correlated with the change and concentration of the respective major constituents. Especially strong bioactivity shown by hydrosols of dried Houttuynia cordata and fresh Prunus pendula was ascribed to n-capric acid and cyanide, respectively. Eight hydrosols exhibited weak or moderate activity against the growth of C. albicans. PMID:22467129

  6. Re-investigation of the Ponzio reaction for the preparation of gem-dinitro compounds

    SciTech Connect

    Honey, P.J.; Millar, R.W.; Coombes, R.G.

    1995-12-01

    Many aromatic nitro compounds can be prepared using mixtures of nitric and sulphuric acids, but, this medium usually results in the destruction of the substrate for aliphatic compounds. Hence a variety of less aggressive nitrating agents in nonacidic media are employed. This talk presents some recent work to re-investigate the Ponzio reaction for the conversion of oximes to the gem-nitro group. The effect of varying the reaction media, and of changing the nitrating species from N{sub 2}O{sub 4} to N{sub 2}O{sub 5} will also be presented. The reaction mechanism will be discussed with reference to CIDNP nmr studies. Where relevant the results will be compared with other aliphatic nitration methods.

  7. Ring flips revisited: (13)C relaxation dispersion measurements of aromatic side chain dynamics and activation barriers in basic pancreatic trypsin inhibitor.

    PubMed

    Weininger, Ulrich; Modig, Kristofer; Akke, Mikael

    2014-07-22

    Intramolecular motions of proteins are critical for biological function. Transient structural fluctuations underlie a wide range of processes, including enzyme catalysis, ligand binding to buried sites, and generic protein motions, such as 180° rotation of aromatic side chains in the protein interior, but remain poorly understood. Understanding the dynamics and molecular nature of concerted motions requires characterization of their rates and energy barriers. Here we use recently developed (13)C transverse relaxation dispersion methods to improve our current understanding of aromatic ring flips in basic pancreatic trypsin inhibitor (BPTI). We validate these methods by benchmarking ring-flip rates against the three previously characterized cases in BPTI, namely, Y23, Y35, and F45. Further, we measure conformational exchange for one additional aromatic ring, F22, which can be interpreted in terms of a flip rate of 666 s(-1) at 5 °C. Upon inclusion of our previously reported result that Y21 also flips slowly [Weininger, U., et al. (2013) J. Phys. Chem. B 117, 9241-9247], the (13)C relaxation dispersion experiments thus reveal relatively slow ring-flip rates for five of eight aromatic residues in BPTI. These results are in contrast with previous reports, which have estimated that all rings, except Y23, Y35, and F45, flip with a high rate at ambient temperature. The (13)C relaxation dispersion data result in an updated rank order of ring-flip rates in BPTI, which agrees considerably better with that estimated from a recent 1 ms molecular dynamics trajectory than do previously published NMR data. However, significant quantitative differences remain between experiment and simulation, in that the latter yields flip rates that are in many cases too fast by 1-2 orders of magnitude. By measuring flip rates across a temperature range of 5-65 °C, we determined the activation barriers of ring flips for Y23, Y35, and F45. Y23 and F45 have identical activation parameters

  8. SiRNAs conjugated with aromatic compounds induce RISC-mediated antisense strand selection and strong gene-silencing activity

    SciTech Connect

    Kubo, Takanori; Yanagihara, Kazuyoshi; Takei, Yoshifumi; Mihara, Keichiro; Sato, Yuichiro; Seyama, Toshio

    2012-10-05

    Highlights: Black-Right-Pointing-Pointer SiRNAs conjugated with aromatic compounds (Ar-siRNAs) at 5 Prime -sense strand were synthesized. Black-Right-Pointing-Pointer Ar-siRNAs increased resistance against nuclease degradation. Black-Right-Pointing-Pointer Ar-siRNAs were thermodynamically stable compared with the unmodified siRNA. Black-Right-Pointing-Pointer High levels of cellular uptake and cytoplasmic localization were found. Black-Right-Pointing-Pointer Strong gene-silencing efficacy was exhibited in the Ar-siRNAs. -- Abstract: Short interference RNA (siRNA) is a powerful tool for suppressing gene expression in mammalian cells. In this study, we focused on the development of siRNAs conjugated with aromatic compounds in order to improve the potency of RNAi and thus to overcome several problems with siRNAs, such as cellular delivery and nuclease stability. The siRNAs conjugated with phenyl, hydroxyphenyl, naphthyl, and pyrenyl derivatives showed strong resistance to nuclease degradation, and were thermodynamically stable compared with unmodified siRNA. A high level of membrane permeability in HeLa cells was also observed. Moreover, these siRNAs exhibited enhanced RNAi efficacy, which exceeded that of locked nucleic acid (LNA)-modified siRNAs, against exogenous Renilla luciferase in HeLa cells. In particular, abundant cytoplasmic localization and strong gene-silencing efficacy were found in the siRNAs conjugated with phenyl and hydroxyphenyl derivatives. The novel siRNAs conjugated with aromatic compounds are promising candidates for a new generation of modified siRNAs that can solve many of the problems associated with RNAi technology.

  9. Mechanistic quantitative structure-activity relationship model for the photoinduced toxicity of polycyclic aromatic hydrocarbons. 2: An empirical model for the toxicity of 16 polycyclic aromatic hydrocarbons to the duckweed Lemna gibba L. G-3

    SciTech Connect

    Huang, X.D.; Krylov, S.N.; Ren, L.; McConkey, B.J.; Dixon, D.G.; Greenberg, B.M.

    1997-11-01

    Photoinduced toxicity of polycyclic aromatic hydrocarbons (PAHs) occurs via photosensitization reactions (e.g., generation of singlet-state oxygen) and by photomodification (photooxidation and/or photolysis) of the chemicals to more toxic species. The quantitative structure-activity relationship (QSAR) described in the companion paper predicted, in theory, that photosensitization and photomodification additively contribute to toxicity. To substantiate this QSAR modeling exercise it was necessary to show that toxicity can be described by empirically derived parameters. The toxicity of 16 PAHs to the duckweed Lemna gibba was measured as inhibition of leaf production in simulated solar radiation (a light source with a spectrum similar to that of sunlight). A predictive model for toxicity was generated based on the theoretical model developed in the companion paper. The photophysical descriptors required of each PAH for modeling were efficiency of photon absorbance, relative uptake, quantum yield for triplet-state formation, and the rate of photomodification. The photomodification rates of the PAHs showed a moderate correlation to toxicity, whereas a derived photosensitization factor (PSF; based on absorbance, triplet-state quantum yield, and uptake) for each PAH showed only a weak, complex correlation to toxicity. However, summing the rate of photomodification and the PSF resulted in a strong correlation to toxicity that had predictive value. When the PSF and a derived photomodification factor (PMF; based on the photomodification rate and toxicity of the photomodified PAHs) were summed, an excellent explanatory model of toxicity was produced, substantiating the additive contributions of the two factors.

  10. Hematotoxic effects of 3,5-dinitro-4-chloro-alpha,alpha,alpha-trifluorotoluene, a water contaminant

    SciTech Connect

    Guastadisegni, C.; Hall, D.; Macri, A.

    1986-10-01

    Three short-term studies of 7, 14, and 21 days, respectively, were made to investigate the nature of the anemia induced in rats by 3,5-dinitro-4-chloro-alpha,alpha,alpha-trifluorotoluene (DNCTT). This compound is an intermediate in the synthesis of dinitroaniline herbicides and was detected as a contaminant of a water-bearing stratum in northern Italy. DNCTT was mixed in a powdered rodent diet at a level of 2000 ppm and administered to Wistar-derived rats. DNCTT was shown to produce a hemolytic anemia of rapid onset; packed cell volume and hemoglobin concentration were decreased at all three treatment periods. Methemoglobin and reticulocyte count were increased in all the treated groups. The relative organ weights of the spleen and the liver were increased compared to those of the control groups. Spleen enlargement was also evident at the macroscopic examination, whereas the liver appearance was normal. Pearl's Prussian blue staining performed on the spleen and liver was highly positive in the spleen of treated rats, but no iron deposition was detected in the liver of treated rats.

  11. Oxidant-dependent metabolic activation of polycyclic aromatic hydrocarbons by phorbol ester-stimulated human polymorphonuclear leukocytes: possible link between inflammation and cancer

    SciTech Connect

    Trush, M.A.; Seed, J.L.; Kensler, T.W.

    1985-08-01

    Oxidants, such as those generated by metabolically activated phagocytes in inflammation, have been implicated in the metabolic activation of carcinogens, and in this study the authors demonstrate that the interaction of (+/-)-trans-7,8-dihydroxy-7,8-dihydrobenzo(a)pyrene (BP 7,8-dihydrodiol) with phorbol ester-stimulated polymorphonuclear leukocytes (PMNs) results in the generation of both a chemiluminescent intermediate and one that covalently binds to DNA. Concordant with the formation of a carcinogen-DNA adduct, the admixture of BP 7,8-dihydrodiol and phorbol ester-stimulated PMNs elicited mutagenesis in Salmonella typhimurium strain TA100. These results demonstrate that oxidants generated by metabolically stimulated PMNs can activate penultimate polycyclic aromatic hydrocarbons to a genotoxic metabolite and further defines a role for inflammation in carcinogenesis.

  12. The Role of Human Aldo-Keto Reductases in the Metabolic Activation and Detoxication of Polycyclic Aromatic Hydrocarbons: Interconversion of PAH Catechols and PAH o-Quinones.

    PubMed

    Zhang, Li; Jin, Yi; Huang, Meng; Penning, Trevor M

    2012-01-01

    Polycyclic aromatic hydrocarbons (PAH) are ubiquitous environmental pollutants. They are procarcinogens requiring metabolic activation to elicit their deleterious effects. Aldo-keto reductases (AKR) catalyze the oxidation of proximate carcinogenic PAH trans-dihydrodiols to yield electrophilic and redox-active PAH o-quinones. AKRs are also found to be capable of reducing PAH o-quinones to form PAH catechols. The interconversion of o-quinones and catechols results in the redox-cycling of PAH o-quinones to give rise to the generation of reactive oxygen species and subsequent oxidative DNA damage. On the other hand, PAH catechols can be intercepted through phase II metabolism by which PAH o-quinones could be detoxified and eliminated. The aim of the present review is to summarize the role of human AKRs in the metabolic activation/detoxication of PAH and the relevance of phase II conjugation reactions to human lung carcinogenesis.

  13. Use of quantitative shape-activity relationships to model the photoinduced toxicity of polycyclic aromatic hydrocarbons: Electron density shape features accurately predict toxicity

    SciTech Connect

    Mezey, P.G.; Zimpel, Z.; Warburton, P.; Walker, P.D.; Irvine, D.G.; Huang, X.D.; Dixon, D.G.; Greenberg, B.M.

    1998-07-01

    The quantitative shape-activity relationship (QShAR) methodology, based on accurate three-dimensional electron densities and detailed shape analysis methods, has been applied to a Lemna gibba photoinduced toxicity data set of 16 polycyclic aromatic hydrocarbon (PAH) molecules. In the first phase of the studies, a shape fragment QShAR database of PAHs was developed. The results provide a very good match to toxicity based on a combination of the local shape features of single rings in comparison to the central ring of anthracene and a more global shape feature involving larger molecular fragments. The local shape feature appears as a descriptor of the susceptibility of PAHs to photomodification and the global shape feature is probably related to photosensitization activity.

  14. Photoinductive activity of humic acid fractions with the presence of Fe(III): the role of aromaticity and oxygen groups involved in fractions.

    PubMed

    Ou, Xiaoxia; Chen, Shuo; Quan, Xie; Zhao, Huimin

    2008-06-01

    Relationship between the photoinductive activity and the properties of humic acids (HA) fractions were investigated with and without Fe(III). Three fractions were separated based on the molecular weight (M(w)) and were obtained following the order of M(w): F(A)>F(B)>F(C). Compared to F(A) and F(B), photodegradation of atrazine under simulated sunlight was much faster in solution containing F(C), whose structure was dominated by greater aromaticity, more oxygen groups and fluorophores. The interaction of HA fractions and Fe(III) was studied using fluorescence spectrometry and F(C) had the largest quenching constant. The capacity of electron transfer, estimated from the amount of photoformed Fe(II), was also highest for F(C). Thus, the Fe(III)-F(C) complex was efficient in phototransformation of atrazine in nearly neutral aqueous solutions. These results suggest that the aromaticity and oxygen groups content of HA exert great influence on the binding ability of metals and on the fate of pollutants in natural waters.

  15. Polycyclic aromatic hydrocarbons, aliphatic hydrocarbons, trace elements, and monooxygenase activity in birds nesting on the North Platte River, Casper, Wyoming, USA.

    PubMed

    Custer, T W; Custer, C M; Dickerson, K; Allen, K; Melancon, M J; Schmidt, L J

    2001-03-01

    Tree swallow (Tachycineta bicolor) and house wren (Troglodytes aedon) eggs and chicks were collected near a refinery site on the North Platte River, Casper. Wyoming, USA and at a reference site 10 km upstream. Total polycyclic aromatic hydrocarbon (PAH) concentrations in swallow and wren chicks were higher at the refinery site than at the reference site. Polycyclic aromatic hydrocarbon concentrations in sediment and chick dietary samples were consistent with these findings. The general lack of methylated PAHs in sediment, diet, and bird carcasses suggested that the PAHs were derived from combustion and not from petroleum. The predominance of odd-numbered aliphatic hydrocarbons and the low ratios (< or =0.25) of pristane:n-C17 and phytane:n-C18 in chick and diet samples also suggested that swallow and wren chicks were not being chronically exposed to petroleum. Mean ethoxyresorufin-O-dealkylase and benzyloxyresorufin-O-dealkylase activities in tree swallow livers averaged nine times higher at the refinery site than at the reference site and were probably induced by exposure to PAHs. Trace element concentrations in eggs and livers of swallows and wrens were similar or greater at the reference site than at the refinery site. Selenium, strontium, and boron concentrations were elevated in eggs and livers of swallows and wrens at both the refinery and reference sites. PMID:11349865

  16. Polycyclic aromatic hydrocarbons, aliphatic hydrocarbons, trace elements and monooxygenase activity in birds nesting on the North Platte River, Casper, Wyoming, USA

    USGS Publications Warehouse

    Custer, T.W.; Custer, Christine M.; Dickerson, K.; Allen, K.; Melancon, M.J.; Schmidt, L.J.

    2001-01-01

    Tree swallow (Tachycineta bicolor) and house wren (Troglodytes aedon) eggs and chicks were collected near a refinery site on the North Platte River, Casper, Wyoming, USA and at a reference site 10 km upstream. Total polycylic aromatic hydrocarbon (PAH) concentrations in swallow and wren chicks were higher at the refinery site than at the reference site. Polycylic aromatic hydrocarbon concentrations in sediment and chick dietary samples were consistent with these findings. The general lack of methylated PAHs in sediment, diet, and bird carcasses suggested that the PAHs were derived from combustion and not from petroleum. The predominance of odd numbered aliphatic hydrocarbons and the low ratios (≤ 0.25) of pristane: n-C17 and phytane: n-C18 in chick and diet samples also suggested that swallow and wren chicks were not being chronically exposed to petroleum. Mean ethoxyresorufin-O-dealkylase and benzyloxyresorufin-O-dealkylase activities in tree swallow livers averaged nine times higher at the refinery site than at the reference site and were probably induced by exposure to PAHs. Trace element concentrations in eggs and livers of swallows and wrens were similar or greater at the reference site than at the refinery site. Selenium, strontium, and boron concentrations were elevated in eggs and livers of swallows and wrens at both the refinery and reference sites.

  17. Pathway engineering for production of aromatics in Escherichia coli: Confirmation of stoichiometric analysis by independent modulation of AroG, TktA, and Pps activities

    SciTech Connect

    Patnaik, R.; Spitzer, R.G.; Liao, J.C.

    1995-05-20

    The synthesis of 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) is the first commitment of resources toward aromatics production in Escherichia coli. DAHP is produced during the condensation reaction between phosphenolpyruvate (PEP) and erythrose 4-phosphate (E4P) catalyzed by DAHP synthases (coded by aroF, aroG, and aroH). Stoichiometric analysis has shown a severe PEP limitation in the theoretical yield of DAHP production from glucose due to the phosphotransferase system (PTS) for sugar uptake. In the present study the authors confirm the predictions of the stoichiometric analysis by introducing pps, tktA, and aroG into vectors under independently controlled promoters, In glucose medium, although TktA has some positive effect on the final DAHP concentration, it has no effect on the yield (percent conversion). With Pps overexpression, the DAHP concentration produced from glucose is increased almost twofold and the yield is approaching the theoretical maximum, the final DAHP concentration and the yield are completely determined by the AroG activity. TktA and Pps play no or insignificant roles, and the yield can reach the theoretical maximum without overexpression of these two enzymes. The results shown hare are important for both rational design of metabolic pathways and industrial production of aromatics such as tryptophan, phenylalanine, indigo, quinic acid, and catechol.

  18. Polybenzimidazoles Via Aromatic Nucleophilic Displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W.; Hergenrother, Paul M.; Smith, Joseph G.

    1994-01-01

    Soluble polybenzimidazoles (PBI's) synthesized by nucleophilic displacement reaction of di(hydroxyphenyl)-benzimidazole monomers with activated aromatic difluoride compounds in presence of anhydrous potassium carbonate. These polymers exhibit good thermal, thermo-oxidative, and chemical stability, and high mechanical properties. Using benzimidazole monomers, more economical, and new PBI's processed more easily than commercial PBI, without loss of desirable physical properties.

  19. Experimental and DFT studies on the aggregation behavior of imidazolium-based surface-active ionic liquids with aromatic counterions in aqueous solution.

    PubMed

    Xu, Wenwen; Wang, Tao; Cheng, Ni; Hu, Qiongzheng; Bi, Yanhui; Gong, Yanjun; Yu, Li

    2015-02-01

    Two imidazolium-based surface-active ionic liquids with aromatic counterions, namely, 1-dodecyl-3-methylimidazolium salicylate (C12mimSal) and 1-dodecyl-3-methylimidazolium 3-hydroxy-2-naphthoate (C12mimHNC), were synthesized, and their aggregate behavior in aqueous solutions was systematically explored. Surface tension and conductivity measurements indicate that both C12mimSal and C12mimHNC show superior surface activity compared to the common imidazolium-based SAIL with the same hydrocarbon chain length, 1-dodecyl-3-methylimidazolium bromide (C12mimBr). This result demonstrates that the incorporation of aromatic counterions favors the formation of micelles. C12mimHNC displays a higher surface activity than C12mimSal, resulting from the different hydrophobicities of the counterions. In comparison with C12mimBr, C12mimSal not only can form hexagonal liquid-crystalline phase (H1) in aqueous solution, but also exhibits a broad region of cubic liquid-crystalline phase (V2) at higher concentration. As for the C12mimHNC/H2O system, a lamellar liquid-crystalline (L(α)) phase was observed. These lyotropic liquid crystals (LLCs) were characterized by polarized optical microscopy (POM) and small-angle X-ray scattering (SAXS). Structural parameters calculated from SAXS patterns suggest that a higher concentration of the SAIL leads to a denser arrangement whereas a higher temperature results in the opposite effect. The rheological results manifest that the formed H1 phase in the C12mimSal/H2O system exhibits an impressive viscoelastic behavior, indicated by a modulus (G' and G″) that is 1 order of magnitude higher than that of C12mimBr. Density functional theory (DFT) calculations reveal that C12mimSal has a more negative interaction energy with a water molecule and the Sal(-) counterion presents a stronger electronegativity than the HNC(-) counterion. The specific phase behavior of the C12mimSal/H2O and C12mimHNC/H2O systems can be attributed to the strong synergic

  20. Contorted polycyclic aromatics.

    PubMed

    Ball, Melissa; Zhong, Yu; Wu, Ying; Schenck, Christine; Ng, Fay; Steigerwald, Michael; Xiao, Shengxiong; Nuckolls, Colin

    2015-02-17

    CONSPECTUS: This Account describes a body of research in the design, synthesis, and assembly of molecular materials made from strained polycyclic aromatic molecules. The strain in the molecular subunits severely distorts the aromatic molecules away from planarity. We coined the term "contorted aromatics" to describe this class of molecules. Using these molecules, we demonstrate that the curved pi-surfaces are useful as subunits to make self-assembled electronic materials. We have created and continue to study two broad classes of these "contorted aromatics": discs and ribbons. The figure that accompanies this conspectus displays the three-dimensional surfaces of a selection of these "contorted aromatics". The disc-shaped contorted molecules have well-defined conformations that create concave pi-surfaces. When these disc-shaped molecules are substituted with hydrocarbon side chains, they self-assemble into columnar superstructures. Depending on the hydrocarbon substitution, they form either liquid crystalline films or macroscopic cables. In both cases, the columnar structures are photoconductive and form p-type, hole- transporting materials in field effect transistor devices. This columnar motif is robust, allowing us to form monolayers of these columns attached to the surface of dielectrics such as silicon oxide. We use ultrathin point contacts made from individual single-walled carbon nanotubes that are separated by a few nanometers to probe the electronic properties of short stacks of a few contorted discs. We find that these materials have high mobility and can sense electron-deficient aromatic molecules. The concave surfaces of these disc-shaped contorted molecules form ideal receptors for the molecular recognition and assembly with spherical molecules such as fullerenes. These interfaces resemble ball-and-socket joints, where the fullerene nests itself in the concave surface of the contorted disc. The tightness of the binding between the two partners can be

  1. Contorted polycyclic aromatics.

    PubMed

    Ball, Melissa; Zhong, Yu; Wu, Ying; Schenck, Christine; Ng, Fay; Steigerwald, Michael; Xiao, Shengxiong; Nuckolls, Colin

    2015-02-17

    CONSPECTUS: This Account describes a body of research in the design, synthesis, and assembly of molecular materials made from strained polycyclic aromatic molecules. The strain in the molecular subunits severely distorts the aromatic molecules away from planarity. We coined the term "contorted aromatics" to describe this class of molecules. Using these molecules, we demonstrate that the curved pi-surfaces are useful as subunits to make self-assembled electronic materials. We have created and continue to study two broad classes of these "contorted aromatics": discs and ribbons. The figure that accompanies this conspectus displays the three-dimensional surfaces of a selection of these "contorted aromatics". The disc-shaped contorted molecules have well-defined conformations that create concave pi-surfaces. When these disc-shaped molecules are substituted with hydrocarbon side chains, they self-assemble into columnar superstructures. Depending on the hydrocarbon substitution, they form either liquid crystalline films or macroscopic cables. In both cases, the columnar structures are photoconductive and form p-type, hole- transporting materials in field effect transistor devices. This columnar motif is robust, allowing us to form monolayers of these columns attached to the surface of dielectrics such as silicon oxide. We use ultrathin point contacts made from individual single-walled carbon nanotubes that are separated by a few nanometers to probe the electronic properties of short stacks of a few contorted discs. We find that these materials have high mobility and can sense electron-deficient aromatic molecules. The concave surfaces of these disc-shaped contorted molecules form ideal receptors for the molecular recognition and assembly with spherical molecules such as fullerenes. These interfaces resemble ball-and-socket joints, where the fullerene nests itself in the concave surface of the contorted disc. The tightness of the binding between the two partners can be

  2. 2-Methyl­pyridinium 5-(2,4-dinitro­phen­yl)-1,3-dimethyl­barbiturate

    PubMed Central

    Sridevi, Gunaseelan; Kalaivani, Doraisamyraja

    2012-01-01

    In the title mol­ecular salt [systematic name: 2-methyl­pyridinium 5-(2,4-dinitro­phen­yl)-1,3-dimethyl-2,6-dioxo-1,2,3,6-tetra­hydro­pyrimidin-4-olate], C6H8N+·C12H9N4O7 −, the cation and anion are linked a through strong N—H⋯O hydrogen bond. In the crystal, C—H⋯O inter­actions link the ions, generating a chain along [010]. PMID:22589914

  3. Differentiation of regioisomeric aromatic ketocarboxylic acids by positive mode atmospheric pressure chemical ionization collision-activated dissociation tandem mass spectrometry in a linear quadrupole ion trap mass spectrometer.

    PubMed

    Amundson, Lucas M; Owen, Benjamin C; Gallardo, Vanessa A; Habicht, Steven C; Fu, Mingkun; Shea, Ryan C; Mossman, Allen B; Kenttämaa, Hilkka I

    2011-04-01

    Positive-mode atmospheric pressure chemical ionization tandem mass spectrometry (APCI-MS(n)) was tested for the differentiation of regioisomeric aromatic ketocarboxylic acids. Each analyte forms exclusively an abundant protonated molecule upon ionization via positive-mode APCI in a commercial linear quadrupole ion trap (LQIT) mass spectrometer. Energy-resolved collision-activated dissociation (CAD) experiments carried out on the protonated analytes revealed fragmentation patterns that varied based on the location of the functional groups. Unambiguous differentiation between the regioisomers was achieved in each case by observing different fragmentation patterns, different relative abundances of ion-molecule reaction products, or different relative abundances of fragment ions formed at different collision energies. The mechanisms of some of the reactions were examined by H/D exchange reactions and molecular orbital calculations.

  4. Structure-activity relationship of genotoxic polycyclic aromatic nitro compounds: Further evidence for the importance of hydrophobicity and molecular orbital energies in genetic toxicity

    SciTech Connect

    Debnath, A.K.; Hansch, C. )

    1992-01-01

    A quantitative structure-activity relationship (QSAR) has been formulated for 15 polycyclic aromatic nitro compounds acting on E. coli PQ37. Upon damage of DNA by these substances [beta]-galactosidase is induced and can be easily assayed colorimetrically, hence, this is a short-term test for mutagenicity. The QSAR (log SOSIP = 1.07 log P - 1.57 e[sub LUMO] - 6.41) is strikingly similar to that found earlier with nitroaromatics acting in the Ames test (TA100) and differs significantly for that found using TA98 organisms. The QSAR brings out in a unique manner the underlying similarity in the two test systems. 24 refs., 2 tabs.

  5. Intramolecular CH Activation and Metallacycle Aromaticity in the Photochemistry of [FeFe]-Hydrogenase Model Compounds in Low-Temperature Frozen Matrices.

    PubMed

    Thornley, Wyatt A; Bitterwolf, Thomas E

    2015-12-01

    The [FeFe]-hydrogenase model complexes [(μ-pdt){Fe(CO)3 }2 ], [(μ-edt){Fe(CO)3 }2 ], and [(μ-mdt){Fe(CO)3 }2 ], where pdt=1,3-propanedithiolate, edt=1,2-ethanedithiolate, and mdt=methanedithiolate, undergo wavelength dependent photodecarbonylation in hydrocarbon matrices at 85 K resulting in multiple decarbonylation isomers. As previously reported in time-resolved solution photolysis experiments, the major photoproduct is attributed to a basal carbonyl-loss species. Apical carbonyl-loss isomers are also generated and may undergo secondary photolysis, resulting in β-hydride activation of the alkyldithiolate bridge, as well as formation of bridging carbonyl isomers. For [(μ-bdt){Fe(CO)3 }2 ], (bdt=1,2-benzenedithiolate), apical photodecarbonylation results in generation of a 10 π-electron aromatic FeS2 C6 H4 metallacycle that coordinates the remaining iron through an η(5) mode.

  6. Heterogeneous photocatalytic reactions of sulfur aromatic compounds.

    PubMed

    Samokhvalov, Alexander

    2011-11-18

    Sulfur aromatic compounds, such as mono-, di-, tri-, and tetraalkyl-substituted thiophene, benzothiophenes, dibenzothiophenes, are the molecular components of many fossils (petroleum, oil shale, tar sands, bitumen). Structural units of natural, cross-linked heteroaromatic polymers present in brown coals, turf, and soil are similar to those of sulfur aromatic compounds. Many sulfur aromatic compounds are found in the streams of petroleum refining and upgrading (naphthas, gas oils) and in the consumer products (gasoline, diesel, jet fuels, heating fuels). Besides fossils, the structural fragments of sulfur aromatic compounds are present in molecules of certain organic semiconductors, pesticides, small molecule drugs, and in certain biomolecules present in human body (pheomelanin pigments). Photocatalysis is the frontier area of physical chemistry that studies chemical reactions initiated by absorption of photons by photocatalysts, that is, upon electronic rather than thermal activation, under "green" ambient conditions. This review provides systematization and critical review of the fundamental chemical and physicochemical information on heterogeneous photocatalysis of sulfur aromatic compounds accumulated in the last 20-30 years. Specifically, the following topics are covered: physicochemical properties of sulfur aromatic compounds, major classes of heterogeneous photocatalysts, mechanisms and reactive intermediates of photocatalytic reactions of sulfur aromatic compounds, and the selectivity of these reactions. Quantum chemical calculations of properties and structures of sulfur aromatic compounds, their reactive intermediates, and the structure of adsorption complexes formed on the surface of the photocatalysts are also discussed.

  7. Monomers for thermosetting and toughening epoxy resins. [glycidyl amine derivatives, propargyl-containing amines, and mutagenic testing of aromatic diamines

    NASA Technical Reports Server (NTRS)

    Pratt, J. R.

    1981-01-01

    Eight glycidyl amines were prepared by alkylating the parent amine with epichlorohydrin to form chlorohydrin, followed by cyclization with aqueous NaOH. Three of these compounds contained propargyl groups with postcuring studies. A procedure for quantitatively estimating the epoxy content of these glycidyl amines was employed for purity determination. Two diamond carbonates and several model propargly compounds were prepared. The synthesis of three new diamines, two which contain propargyloxy groups, and another with a sec-butyl group is in progress. These materials are at the dinitro stage ready for the final hydrogenation step. Four aromatic diamines were synthesized for mutagenic testing purposes. One of these compounds rapidly decomposes on exposure to air.

  8. Extreme Modulation Properties of Aromatic Fluorine

    SciTech Connect

    Burnett, Michael N; Gakh, Andrei A

    2011-01-01

    Thorough examination of the current literature as well as publicly available databases allowed us to qualify aromatic fluorine as a unique modulator of biological properties of organic compounds. In some rare cases, introduction of fluorine increased biological activity 100,000 times and even higher. We have also identified several examples where aromatic fluorine substantially reduced biological activity. Selected individual cases of extreme modulation are presented and discussed in the paper.

  9. A NOVEL METABOLIC ACTIVATION PATHWAY FOR POLYCYCLIC AROMATIC HYDROCARBONS: REACTIVE OXYGEN SPECIES-MEDIATED DNA DAMAGE AND MORPHOLOGICAL CELL TRANSFORMATION IN MOUSE EMBRYO CELLS BY K-REGION DIOL METABOLITES

    EPA Science Inventory

    Benzo[ a ]pyrene (BP) is a well-studied polycyclic aromatic hydrocarbon (P AH) .Many
    mechanisms have been suggested to explain its carcinogenic activity, yet many questions still
    remain. K-region dihydrodiols (diols) ofPAHs are common metabolites and some are genotoxic. W...

  10. Aromatic inhibitors derived from ammonia-pretreated lignocellulose hinder bacterial ethanologenesis by activating regulatory circuits controlling inhibitor efflux and detoxification

    PubMed Central

    Keating, David H.; Zhang, Yaoping; Ong, Irene M.; McIlwain, Sean; Morales, Eduardo H.; Grass, Jeffrey A.; Tremaine, Mary; Bothfeld, William; Higbee, Alan; Ulbrich, Arne; Balloon, Allison J.; Westphall, Michael S.; Aldrich, Josh; Lipton, Mary S.; Kim, Joonhoon; Moskvin, Oleg V.; Bukhman, Yury V.; Coon, Joshua J.; Kiley, Patricia J.; Bates, Donna M.; Landick, Robert

    2014-01-01

    Efficient microbial conversion of lignocellulosic hydrolysates to biofuels is a key barrier to the economically viable deployment of lignocellulosic biofuels. A chief contributor to this barrier is the impact on microbial processes and energy metabolism of lignocellulose-derived inhibitors, including phenolic carboxylates, phenolic amides (for ammonia-pretreated biomass), phenolic aldehydes, and furfurals. To understand the bacterial pathways induced by inhibitors present in ammonia-pretreated biomass hydrolysates, which are less well studied than acid-pretreated biomass hydrolysates, we developed and exploited synthetic mimics of ammonia-pretreated corn stover hydrolysate (ACSH). To determine regulatory responses to the inhibitors normally present in ACSH, we measured transcript and protein levels in an Escherichia coli ethanologen using RNA-seq and quantitative proteomics during fermentation to ethanol of synthetic hydrolysates containing or lacking the inhibitors. Our study identified four major regulators mediating these responses, the MarA/SoxS/Rob network, AaeR, FrmR, and YqhC. Induction of these regulons was correlated with a reduced rate of ethanol production, buildup of pyruvate, depletion of ATP and NAD(P)H, and an inhibition of xylose conversion. The aromatic aldehyde inhibitor 5-hydroxymethylfurfural appeared to be reduced to its alcohol form by the ethanologen during fermentation, whereas phenolic acid and amide inhibitors were not metabolized. Together, our findings establish that the major regulatory responses to lignocellulose-derived inhibitors are mediated by transcriptional rather than translational regulators, suggest that energy consumed for inhibitor efflux and detoxification may limit biofuel production, and identify a network of regulators for future synthetic biology efforts. PMID:25177315

  11. Poly(arylene ether)s That Resist Atomic Oxygen

    NASA Technical Reports Server (NTRS)

    Connell, John W.; Hergenrother, Paul; Smith, Joseph G., Jr.

    1994-01-01

    Novel poly(arylene ether)s containing phosphine oxide (PAEPO's) made via aromatic nucleophilic displacement reactions of activated aromatic dihalides (or, in some cases, activated aromatic dinitro compounds) with new bisphenol monomers containing phosphine oxide. Exhibited favorable combination of physical and mechanical properties and resistance to monatomic oxygen in oxygen plasma environment. Useful as adhesives, coatings, films, membranes, moldings, and composite matrices.

  12. N,N-Diethyl-anilinium 5-(2,4-dinitro-phen-yl)-2,6-dioxo-1,2,3,6-tetra-hydro-pyrimidin-4-olate.

    PubMed

    Kalaivani, Doraisamyraja; Mangaiyarkarasi, Govindan

    2013-01-01

    The asymmetric unit of the title mol-ecular salt, C10H16N(+)·C10H5N4O7(-) (trivial name: N,N-diethyl-anilinium 2,4-dinitro-phenyl-barbiturate), comprises two anion-cation units. In the anions, the dinitro-phenyl ring and the mean plane of the barbiturate ring [planar to within 0.011 (2) and 0.023 (2) Å in the two anions] are inclined to one another by 41.47 (9) and 45.12 (9)°. In the crystal, the anions are linked via strong N-H⋯O hydrogen bonds, forming chains propagating along [10-1]. Within the chains, adjacent inversion-related anionic barbiturate entities are joined through R2(2)(8) ring motifs. The cations are linked to the chains via N-H⋯O hydrogen bonds. The chains are linked via a number of C-H⋯O inter-actions, forming a three-dimensional structure. PMID:23476417

  13. Modulation of aromatic amine mutagenicity in Salmonella typhimurium with rat-liver 9000 g supernatant or monolayers of rat hepatocytes as an activation system.

    PubMed

    Holme, J A; Haug, L T; Dybing, E

    1983-04-01

    2-Aminofluorene (AF), 2-acetylaminofluorene (AAF) and N-hydroxy-2-acetylaminofluorene (N-OH-AAF) were studied for mutagenic activity in S. typhimurium and either liver 9000 g supernatant fractions (S9) or monolayer cultures of hepatocytes isolated from Wistar rats were used as an activation system. All 3 compounds were converted into mutagens excreted into the incubation medium by the cell-culture system, with N-OH-AAF greater than AF greater than AAF. Cultures used 24 h after plating were less efficient in promutagen conversion than were cultures used after 2 h. Phenobarbital, but not 3-methylcholanthrene, pretreatment of the rats caused similar effects on AF, AAF and N-OH-AAF mutagenicity with both S9 and hepatocyte cultures. The mutagenicities of AF and AAF were reduced by the cytochrome-P-450 inhibitors metyrapone and alpha-naphthoflavone, whereas the mutagenicity of N-OH-AAF was increased by using both inhibitors. Further, the microsomal deacetylase inhibitor paraoxon caused only a moderate reduction in N-OH-AAF mutagenicity, but a total inhibition of AAF mutagenicity. No significant effect of paraoxon on AF mutagenicity was seen. With the S9 system, no effect of ascorbate on the mutagenicity of AF, AAF or N-OH-AAF was observed. In contrast, the mutagenicity of all 3 compounds was increased by ascorbate when hepatocyte cultures were used as activation system. Incubation of hepatocyte monolayers in a sulfate-free medium did not change the mutagenicity of AF, AAF or N-OH-AAF. Galactosamine, an inhibitor of glucuronidation in cells, increased the mutagenicity of AF, AAF and N-OH-AAF with hepatocyte cultures. The addition of cofactor for glucuronidation in the S9 system, however, had no effect. A reduction in mutagenicity of AF and AAF, but not that of N-OH-AAF, was observed with the addition of glutathione (GSH) in both the S9 and the hepatocyte systems. On the other hand, no effect of cellular GSH depletion was seen on aromatic-amine mutagenicity in the

  14. Quantitative structure-activity relationship investigation of the role of hydrophobicity in regulating mutagenicity in the Ames test: 2. Mutagenicity of aromatic and heteroaromatic nitro compounds in Salmonella typhimurium TA100

    SciTech Connect

    Debnath, A.K.; Hansch, C. ); Shusterman, A.J. ); Lopez de Compadre, R.L. )

    1992-01-01

    A quantitative structure-activity relationship (QSAR) has been derived for the mutagenic activity of 117 aromatic and heteroaromatic nitro compounds acting on Salmonella typhimurium TA100. Relative mutagenic activity is bilinearly dependent on hydrophobicity, with an optimal log P of 5.44, and is linearly dependent on the energy of the lowest unoccupied molecular orbital of the nitro compound. The dependence of mutagenic activity on hydrophobicity and electronic effects is very similar for TA98 and TA100. Mutagenic activity in TA100 does not depend on the size of the aromatic ring system, as it does in TA98. The effect of the choice of assay organism, TA98 versus TA100, on nitroarene QSAR is seen to be similar to the effect previously found for aminoarenes. Lateral verification of QSARs is presented as a tool for establishing the significance of a new QSAR.

  15. Metabolic Activation of Polycyclic Aromatic Hydrocarbons and Aryl and Heterocyclic Amines by Human Cytochromes P450 2A13 and 2A6

    PubMed Central

    Shimada, Tsutomu; Murayama, Norie; Yamazaki, Hiroshi; Tanaka, Katsuhiro; Takenaka, Shigeo; Komori, Masayuki; Kim, Donghak; Guengerich, F. Peter

    2013-01-01

    Human cytochrome P450 (P450) 2A13 was found to interact with several polycyclic aromatic hydrocarbons (PAHs) to produce Type I binding spectra, including acenaphthene, acenaphthylene, benzo[c]phenanthrene, fluoranthene, fluoranthene-2,3-diol, and 1-nitropyrene. P450 2A6 also interacted with acenaphthene and acenaphthylene, but not with fluoranthene, fluoranthene-2,3-diol, or 1-nitropyrene. P450 1B1 is well known to oxidize many carcinogenic PAHs, and we found that several PAHs (i.e., 7,12-dimethylbenz[a]anthracene, 7,12-dimethylbenz[a]anthracene-5,6-diol, benzo[c]phenanthrene, fluoranthene, fluoranthene-2,3-diol, 5-methylchrysene, benz[a]pyrene-4,5-diol, benzo[a]pyrene-7,8-diol, 1-nitropyrene, 2-aminoanthracene, 2-aminofluorene, and 2-acetylaminofluorene) interacted with P450 1B1, producing Reverse Type I binding spectra. Metabolic activation of PAHs and aryl- and heterocyclic amines to genotoxic products was examined in Salmonella typhimurium NM2009, and we found that P450 2A13 and 2A6 (as well as P450 1B1) were able to activate several of these procarcinogens. The former two enzymes were particularly active in catalyzing 2-aminofluorene and 2-aminoanthracene activation, and molecular docking simulations supported the results with these procarcinogens, in terms of binding in the active sites of P450 2A13 and 2A6. These results suggest that P450 2A enzymes, as well as P450 Family 1 enzymes including P450 1B1, are major enzymes involved in activating PAHs and aryl- and heterocyclic amines, as well as tobacco-related nitrosamines. PMID:23432465

  16. Metabolic activation of N-hydroxy arylamines, N-hydroxy heterocyclic amines and ring-hydroxymethyl polycyclic aromatic hydrocarbons by human sulfotransferases

    SciTech Connect

    Chou, H.C.

    1993-01-01

    Arylamines and polycyclic aromatic hydrocarbons (PAHs) are two major classes of chemical carcinogens. N-Hydroxylation of arylamines is regarded to be a necessary process for their mutagenicity and carcinogenicity, while alkyl-hydroxylation is the major metabolic pathway for alkyl-substituted PAHs. Evidence has been presented that sulfation of several N-hydroxy arylamines and hydroxymethyl PAHs is an important pathway leading to the formation of ultimate carcinogens in experiment animals. Sulfation of these chemicals forms putative sulfuric acid ester intermediates that can rearrange to electrophilic nitrenium or carbenium ions capable of forming covalent adducts with important cellular macromolecules. In order to study the metabolic activation by sulfotransferase(s) in various human tissue preparations an in vitro enzymatic assay was established. A metabolic phenotyping method was also developed for thermostable phenolsulfotransferase (TS-PST) in platelet homogenates (correlated with TS-PST activity in other tissues) based on a simple colorimetric assay using 2-naphthol as substrate. By using a PAPS-regenerating system to supply the activated sulfate and calf thymus DNA to trap the reactive metabolites, we found that N-hydroxy derivatives of the carcinogens, 4-aminobiphenyl (4-ABP), 4,4[prime]-methylene-bis(2-chloroaniline) (MOCA), 2-acetylaminofluorene (2-AAF), 2-aminofluorene (2-AF), 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP), and 2-amino-6-methyldipyrido [1,2-1:3[prime],2[prime]-d]imidazole (Glu-P-1) were metabolically activated by human TS-PST. On the other hand, three methyl-hydroxylated derivatives (7-OH, 12-OH, and 7,12-diOH) of 7, 12-dimethylbenz[a]anthracene (DMBA) were metabolically activated by human steroid sulfotransferase. Human sulfotransferase(s)-mediated activation of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) or 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) was not observed.

  17. Passive dosing of polycyclic aromatic hydrocarbon (PAH) mixtures to terrestrial springtails: linking mixture toxicity to chemical activities, equilibrium lipid concentrations, and toxic units.

    PubMed

    Schmidt, Stine N; Holmstrup, Martin; Smith, Kilian E C; Mayer, Philipp

    2013-07-01

    A 7-day mixture toxicity experiment with the terrestrial springtail Folsomia candida was conducted, and the effects were linked to three different mixture exposure parameters. Passive dosing from silicone was applied to tightly control exposure levels and compositions of 12 mixture treatments, containing the polycyclic aromatic hydrocarbons (PAHs) naphthalene, phenanthrene, and pyrene. Springtail lethality was then linked to sum chemical activities (∑a), sum equilibrium lipid concentrations (∑C(lipid eq.)), and sum toxic units (∑TU). In each case, the effects of all 12 mixture treatments could be fitted to one sigmoidal exposure-response relationship. The effective lethal chemical activity (La50) of 0.027 was well within the expected range for baseline toxicity of 0.01-0.1. Linking the effects to the lipid-based exposure parameter yielded an effective lethal concentration (LC(lipid eq 50)) of 133 mmol kg(-1) lipid in good correspondence with the lethal membrane burden for baseline toxicity (40-160 mmol kg(-1) lipid). Finally, the effective lethal toxic unit (LTU50) of 1.20 was rather close to the expected value of 1. Altogether, passive dosing provided tightly controlled mixture exposure in terms of both level and composition, while ∑a, ∑C(lipid eq.), and ∑TU allowed baseline toxicity to be linked to mixture exposure. PMID:23473585

  18. Passive dosing of polycyclic aromatic hydrocarbon (PAH) mixtures to terrestrial springtails: linking mixture toxicity to chemical activities, equilibrium lipid concentrations, and toxic units.

    PubMed

    Schmidt, Stine N; Holmstrup, Martin; Smith, Kilian E C; Mayer, Philipp

    2013-07-01

    A 7-day mixture toxicity experiment with the terrestrial springtail Folsomia candida was conducted, and the effects were linked to three different mixture exposure parameters. Passive dosing from silicone was applied to tightly control exposure levels and compositions of 12 mixture treatments, containing the polycyclic aromatic hydrocarbons (PAHs) naphthalene, phenanthrene, and pyrene. Springtail lethality was then linked to sum chemical activities (∑a), sum equilibrium lipid concentrations (∑C(lipid eq.)), and sum toxic units (∑TU). In each case, the effects of all 12 mixture treatments could be fitted to one sigmoidal exposure-response relationship. The effective lethal chemical activity (La50) of 0.027 was well within the expected range for baseline toxicity of 0.01-0.1. Linking the effects to the lipid-based exposure parameter yielded an effective lethal concentration (LC(lipid eq 50)) of 133 mmol kg(-1) lipid in good correspondence with the lethal membrane burden for baseline toxicity (40-160 mmol kg(-1) lipid). Finally, the effective lethal toxic unit (LTU50) of 1.20 was rather close to the expected value of 1. Altogether, passive dosing provided tightly controlled mixture exposure in terms of both level and composition, while ∑a, ∑C(lipid eq.), and ∑TU allowed baseline toxicity to be linked to mixture exposure.

  19. Activity and viability of polycyclic aromatic hydrocarbon-degrading Sphingomonas sp. LB126 in a DC-electrical field typical for electrobioremediation measures.

    PubMed

    Shi, Lei; Müller, Susann; Loffhagen, Norbert; Harms, Hauke; Wick, Lukas Y

    2008-01-01

    There has been growing interest in employing electro-bioremediation, a hybrid technology of bioremediation and electrokinetics for the treatment of contaminated soil. Knowledge however on the effect of weak electrokinetic conditions on the activity and viability of pollutant-degrading microorganisms is scarce. Here we present data about the influence of direct current (DC) on the membrane integrity, adenosine triphosphate (ATP) pools, physico-chemical cell surface properties, degradation kinetics and culturability of fluorene-degrading Sphingomonas sp. LB126. Flow cytometry was applied to quantify the uptake of propidium iodide (PI) and the membrane potential-related fluorescence intensities (MPRFI) of individual cells within a population. Adenosine tri-phosphate contents and fluorene biodegradation rates of bulk cultures were determined and expressed on a per cell basis. The cells' surface hydrophobicity and electric charge were assessed by contact angle and zeta potential measurements respectively. Relative to the control, DC-exposed cells exhibited up to 60% elevated intracellular ATP levels and yet remained unaffected on all other levels of cellular integrity and functionality tested. Our data suggest that direct current (X=1 V cm(-1); J=10.2 mA cm(-2)) as typically used for electrobioremediation measures has no negative effect on the activity of the polycyclic aromatic hydrocarbon (PAH)-degrading soil microorganism, thereby filling a serious gap of the current knowledge of the electrobioremediation methodology. PMID:21261821

  20. A predictive quantitative structure-activity relationship model for the photoinduced toxicity of polycyclic aromatic hydrocarbons to Daphnia magna with the use of factors for photosensitization and photomodification.

    PubMed

    Lampi, Mark A; Gurska, Jolanta; Huang, Xiao-Dong; Dixon, D George; Greenberg, Bruce M

    2007-03-01

    Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants that readily absorb environmentally relevant solar ultraviolet radiation. On absorption of a photon, photoinduced toxicity of PAHs is manifested through photosensitization and photomodification. Both of these processes occur under environmentally relevant levels of actinic radiation. An empirical quantitative structure-activity relationship model previously developed was explanatory of photoinduced toxicity of 16 PAHs in Lemna gibba (duckweed). This model was found to be predictive of toxicity to Vibrio fischeri. The L. gibba quantitative structure-activity relationship showed that a photosensitization factor and a photomodification factor could be combined to describe photoinduced toxicity. To further examine this model, we assessed whether it could be applied to Daphnia magna (water flea), a key bioindicator species in aquatic ecosystems. Toxicity was assessed as median effective concentration and median effective time for immobility. As with L. gibba and V. fischeri, neither the photosensitization factor nor the photomodification factor alone correlated to toxicity in D. magna. However, a photosensitization factor modified for D. magna exhibited a correlation to toxicity (r2 = 0.86), which was modestly improved when summed with a modified photomodification factor (r2 = 0.92). The greatest correlation was observed with median effective concentration data. This research provides evidence that models incorporating factors for photosensitization and photomodification have interspecies applicability. PMID:17373503

  1. Mixed ligand complexes of Cu(II)-2-(2-pyridyl)-benzimidazole and aliphatic or aromatic dicarboxylic acids: Synthesis, characterization and biological activity

    NASA Astrophysics Data System (ADS)

    El-Sherif, Ahmed A.; Jeragh, Bakir J. A.

    2007-11-01

    The synthesis and structural characterization of mixed ligand complexes derived from 2-(2-pyridyl)-benzimidazole (PBI) (1ry ligand) and aliphatic or aromatic dicarboxylic acids (2ry ligand) are reported. Cu(II) complexes were characterized on the bases of their elemental analyses, IR, ESR and thermal analyses. The elemental analysis indicated the formation of mixed ligand complexes in a mole ratio 1:1:1 (Cu:L 1:L 2), L 1 = PBI and L 2 = oxalic acid, phthalic acid or malonic acid. IR spectra showed that PBI acts as a neutral bidentate coordinated to the Cu(II) via the pyridyl and imidazolyl nitrogen atoms. The dicarboxylic acids are bidentate with monodentate carboxylate groups. Thermal decomposition study of complexes was monitored by thermogravimetric (TG) and derivative thermogravimetric (DTG) analysis in N 2 atmosphere. The decomposition course and steps were analysed and the activation parameters of the nonisothermal decomposition were calculated from the TG curves and discussed. The isolated metal chelates were screened for their antimicrobial activities and the results are reported, discussed and compared with some known antibiotics.

  2. A predictive quantitative structure-activity relationship model for the photoinduced toxicity of polycyclic aromatic hydrocarbons to Daphnia magna with the use of factors for photosensitization and photomodification.

    PubMed

    Lampi, Mark A; Gurska, Jolanta; Huang, Xiao-Dong; Dixon, D George; Greenberg, Bruce M

    2007-03-01

    Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants that readily absorb environmentally relevant solar ultraviolet radiation. On absorption of a photon, photoinduced toxicity of PAHs is manifested through photosensitization and photomodification. Both of these processes occur under environmentally relevant levels of actinic radiation. An empirical quantitative structure-activity relationship model previously developed was explanatory of photoinduced toxicity of 16 PAHs in Lemna gibba (duckweed). This model was found to be predictive of toxicity to Vibrio fischeri. The L. gibba quantitative structure-activity relationship showed that a photosensitization factor and a photomodification factor could be combined to describe photoinduced toxicity. To further examine this model, we assessed whether it could be applied to Daphnia magna (water flea), a key bioindicator species in aquatic ecosystems. Toxicity was assessed as median effective concentration and median effective time for immobility. As with L. gibba and V. fischeri, neither the photosensitization factor nor the photomodification factor alone correlated to toxicity in D. magna. However, a photosensitization factor modified for D. magna exhibited a correlation to toxicity (r2 = 0.86), which was modestly improved when summed with a modified photomodification factor (r2 = 0.92). The greatest correlation was observed with median effective concentration data. This research provides evidence that models incorporating factors for photosensitization and photomodification have interspecies applicability.

  3. Hydroxylation activity of P450 BM-3 mutant F87V towards aromatic compounds and its application to the synthesis of hydroquinone derivatives from phenolic compounds.

    PubMed

    Sulistyaningdyah, Woro Triarsi; Ogawa, Jun; Li, Qing-Shan; Maeda, Chiharu; Yano, Yuki; Schmid, Rolf D; Shimizu, Sakayu

    2005-06-01

    Cytochrome P450 BM-3 from Bacillus megaterium is a fatty acid hydroxylase exhibiting selectivity for long-chain substrates (12-20 carbons). Replacement of Phe87 in P450 BM-3 by Val (F87V) greatly increased its activity towards a variety of aromatic and phenolic compounds. The apparent initial reaction rates of F87V as to benzothiophene, indan, 2,6-dichlorophenol, and 2-(benzyloxy)phenol were 227, 204, 129, and 385 nmol min(-1) nmol(-1) P450, which are 220-, 66-, 99-, and 963-fold those of the wild type, respectively. These results indicate that Phe87 plays a critical role in the control of the substrate specificity of P450 BM-3. Furthermore, F87V catalyzed regioselective hydroxylation at the para position of various phenolic compounds. In particular, F87V showed high activity as to the hydroxylation of 2-(benzyloxy)phenol to 2-(benzyloxy)hydroquinone. With F87V as the catalyst, 0.71 mg ml(-1) 2-(benzyloxy)hydroquinone was produced from 1.0 mg ml(-1) 2-(benzyloxy)phenol in 4 h, with a molar yield of 66%.

  4. Activity and viability of polycyclic aromatic hydrocarbon‐degrading Sphingomonas sp. LB126 in a DC‐electrical field typical for electrobioremediation measures

    PubMed Central

    Shi, Lei; Müller, Susann; Loffhagen, Norbert; Harms, Hauke; Wick, Lukas Y.

    2008-01-01

    Summary There has been growing interest in employing electro‐bioremediation, a hybrid technology of bioremediation and electrokinetics for the treatment of contaminated soil. Knowledge however on the effect of weak electrokinetic conditions on the activity and viability of pollutant‐degrading microorganisms is scarce. Here we present data about the influence of direct current (DC) on the membrane integrity, adenosine triphosphate (ATP) pools, physico‐chemical cell surface properties, degradation kinetics and culturability of fluorene‐degrading Sphingomonas sp. LB126. Flow cytometry was applied to quantify the uptake of propidium iodide (PI) and the membrane potential‐related fluorescence intensities (MPRFI) of individual cells within a population. Adenosine tri‐phosphate contents and fluorene biodegradation rates of bulk cultures were determined and expressed on a per cell basis. The cells' surface hydrophobicity and electric charge were assessed by contact angle and zeta potential measurements respectively. Relative to the control, DC‐exposed cells exhibited up to 60% elevated intracellular ATP levels and yet remained unaffected on all other levels of cellular integrity and functionality tested. Our data suggest that direct current (X = 1 V cm−1; J = 10.2 mA cm−2) as typically used for electrobioremediation measures has no negative effect on the activity of the polycyclic aromatic hydrocarbon (PAH)‐degrading soil microorganism, thereby filling a serious gap of the current knowledge of the electrobioremediation methodology. PMID:21261821

  5. Antioxidant activity, phenolic content, and peroxide value of essential oil and extracts of some medicinal and aromatic plants used as condiments and herbal teas in Turkey.

    PubMed

    Ozcan, Mehmet Musa; Erel, Ozcan; Herken, Emine Etöz

    2009-02-01

    The antioxidant activity, total peroxide values, and total phenol contents of several medicinal and aromatic plant essential oil and extracts from Turkey were examined. Total phenolic contents were determined using a spectrophotometric technique and calculated as gallic acid equivalents. Total antioxidant activity of essential oil and extracts varied from 0.6853 to 1.3113 and 0.3189 to 0.6119 micromol of Trolox equivalents/g, respectively. The total phenolic content of essential oil ranged from 0.0871 to 0.5919 mg of gallic acid/g dry weight. However, the total phenolic contents of extracts were found to be higher compared with those of essential oils. The amount of total peroxide values of oils varied from 7.31 (pickling herb) to 58.23 (bitter fennel flower) mumol of H(2)O(2)/g. As a result, it is shown that medicinal plant derivatives such as extract and essential oils can be useful as a potential source of total phenol, peroxide, and antioxidant capacity for protection of processed foods. PMID:19298216

  6. Influence of urban activities on polycyclic aromatic hydrocarbons in precipitation: distribution, sources and depositional flux in a developing metropolis, Fortaleza, Brazil.

    PubMed

    Cavalcante, Rivelino M; Sousa, Francisco W; Nascimento, Ronaldo F; Silveira, Edilberto R; Viana, Rommel B

    2012-01-01

    We measured polycyclic aromatic hydrocarbons (PAHs) in bulk precipitation in the Fortaleza metropolitan area, Ceará, Brazil, for the first time. Because little information is available concerning PAHs in tropical climatic regions, we assessed their spatial distribution and possible sources and the influence of urban activities on the depositional fluxes of PAHs in bulk precipitation. The concentrations of individual and total PAHs (Σ(PAHs)) in bulk precipitation ranged from undetectable to 133.9 ng.L(-1) and from 202.6 to 674.8 ng.L(-1), respectively. The plume of highest concentrations was most intense in a zone with heavy automobile traffic and favorable topography for the concentration of emitted pollutants. The depositional fluxes of PAHs in bulk precipitation calculated in this study (undetectable to 0.87 μg.m(-2).month(-1)) are 4 to 27 times smaller than those reported from tourist sites and industrial and urban areas in the Northern Hemisphere. Diagnostic ratio analyses of PAH samples showed that the major source of emissions is gasoline exhaust, with a small percentage originating from diesel fuel. Contributions from coal and wood combustion were also found. Major economic activities appear to contribute to pollutant emissions.

  7. N-terminal aromatic residues closely impact the cytolytic activity of cupiennin 1a, a major spider venom peptide.

    PubMed

    Kuhn-Nentwig, Lucia; Sheynis, Tania; Kolusheva, Sofiya; Nentwig, Wolfgang; Jelinek, Raz

    2013-12-01

    Cupiennins are small cationic α-helical peptides from the venom of the ctenid spider Cupiennius salei which are characterized by high bactericidal as well as hemolytic activities. To gain insight into the determinants responsible for the broad cytolytic activities, two analogues of cupiennin 1a with different N-terminal hydrophobicities were designed. The insecticidal, bactericidal and hemolytic activities of these analogues were assayed and compared to the native peptide. Specifically, substitution of two N-terminal Phe residues by Ala results in less pronounced insecticidal and cytolytic activity, whereas a substitution by Lys reduces strongly its bactericidal activity and completely diminishes its hemolytic activity up to very high tested concentrations. Biophysical analyses of peptide/bilayer membrane interactions point to distinct interactions of the analogues with lipid bilayers, and dependence upon membrane surface charge. Indeed, we find that lower hemolytic activity was correlated with less surface association of the analogues. In contrast, our data indicate that the reduced bactericidal activity of the two cupiennin 1a analogues likely correspond to greater bilayer-surface localization of the peptides. Overall, ultimate insertion and destruction of the host cell membrane is highly dependent on the presence of Phe-2 and Phe-6 (Cu 1a) or Leu-6 (Cu 2a) in the N-terminal sequences of native cupiennins.

  8. Comparison in the in vitro inhibitory effects of major phytocannabinoids and polycyclic aromatic hydrocarbons contained in marijuana smoke on cytochrome P450 2C9 activity.

    PubMed

    Yamaori, Satoshi; Koeda, Kyoko; Kushihara, Mika; Hada, Yui; Yamamoto, Ikuo; Watanabe, Kazuhito

    2012-01-01

    Inhibitory effects of Δ⁹-tetrahydrocannabinol (Δ⁹-THC), cannabidiol (CBD), and cannabinol (CBN), the three major constituents in marijuana, and polycyclic aromatic hydrocarbons (PAHs) contained in marijuana smoke on catalytic activity of human cytochrome P450 (CYP) 2C9 were investigated. These phytocannabinoids concentration-dependently inhibited S-warfarin 7-hydroxylase and diclofenac 4'-hydroxylase activities of human liver microsomes (HLMs) and recombinant CYP2C9 (rCYP2C9). In contrast, none of the twelve PAHs including benz[a]anthracene and benzo[a]pyrene exerted substantial inhibition (IC₅₀ > 10 µM). The inhibitory potentials of Δ⁹-THC (Ki = 0.937-1.50 µM) and CBN (Ki = 0.882-1.29 µM) were almost equivalent regardless of the enzyme sources used, whereas the inhibitory potency of CBD (Ki > = 0.954-9.88 µM) varied depending on the enzyme sources and substrates used. Δ⁹-THC inhibited both S-warfarin 7-hydroxylase and diclofenac 4'-hydroxylase activities of HLMs and rCYP2C9 in a mixed manner. CBD and CBN competitively inhibited the activities of HLMs and rCYP2C9, with the only notable difference being that CBD and CBN exhibited mixed-type inhibitions against diclofenac 4'-hydroxylation and S-warfarin 7-hydroxylation, respectively, by rCYP2C9. None of Δ⁹-THC, CBD, and CBN exerted metabolism-dependent inhibition. These results indicated that the three major phytocannabinoids but not PAHs contained in marijuana smoke potently inhibited CYP2C9 activity and that these cannabinoids can be characterized as direct inhibitors for CYP2C9.

  9. Aromatic-turmerone attenuates invasion and expression of MMP-9 and COX-2 through inhibition of NF-κB activation in TPA-induced breast cancer cells.

    PubMed

    Park, Sun Young; Kim, Young Hun; Kim, YoungHee; Lee, Sang-Joon

    2012-12-01

    Recent evidence suggests that breast cancer is one of the most common forms of malignancy in females, and metastasis from the primary cancer site is the main cause of death. Aromatic (ar)-turmerone is present in Curcuma longa and is a common remedy and food. In the present study, we investigated the inhibitory effects of ar-turmerone on expression and enzymatic activity levels of 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced matrix metalloproteinase (MMP)-9 and cyclooxygenaase-2 (COX-2) in breast cancer cells. Our data indicated that ar-turmerone treatment significantly inhibited enzymatic activity and expression of MMP-9 and COX-2 at non-cytotoxic concentrations. However, the expression of tissue inhibitor of metalloproteinase (TIMP)-1, TIMP-2, MMP-2, and COX-1 did not change upon ar-turmerone treatment. We found that ar-turmerone inhibited the activation of NF-κB, whereas it did not affect AP-1 activation. Moreover, The ChIP assay revealed that in vivo binding activities of NF-κB to the MMP-9 and COX-2 promoter were significantly inhibited by ar-turmerone. Our data showed that ar-turmerone reduced the phosphorylation of PI3K/Akt and ERK1/2 signaling, whereas it did not affect phosphorylation of JNK or p38 MAPK. Thus, transfection of breast cancer cells with PI3K/Akt and ERK1/2 siRNAs significantly decreased TPA-induced MMP-9 and COX-2 expression. These results suggest that ar-turmerone suppressed the TPA-induced up-regulation of MMP-9 and COX-2 expression by blocking NF-κB, PI3K/Akt, and ERK1/2 signaling in human breast cancer cells. Furthermore, ar-turmerone significantly inhibited TPA-induced invasion, migration, and colony formation in human breast cancer cells.

  10. Effect of steam activated biochar application to industrially contaminated soils on bioavailability of polycyclic aromatic hydrocarbons and ecotoxicity of soils.

    PubMed

    Kołtowski, Michał; Hilber, Isabel; Bucheli, Thomas D; Oleszczuk, Patryk

    2016-10-01

    The aim of this study was to determine the effect of steam activation of biochars on the immobilization of freely dissolved (Cfree) and bioaccessible fraction (Cbioacc) of PAHs in soils. Additionally, the toxicity to various organisms like Vibrio fischeri, Lepidium sativum and Folsomia candida was measured before and after the amendment of biochars to soils. Three biochars produced from willow, coconut and wheat straw were steam activated and added to three different soils with varying content and origin of PAHs (coke vs. bitumen). The soils with the addition of the biochars (activated and non-activated) were incubated for a period of 60days. Steam activation of the biochars resulted in more pronounced reduction of both Cfree and Cbioacc. The range of the increase in effectiveness was from 10 to 84% for Cfree and from 50 to 99% for Cbioacc. In contrast, the effect of activation on the toxicity of the soils studied varied greatly and was specific to a particular test and soil type. Essentially, biochar activation did not result in a change of phytotoxicity, but it increased or decreased (depending on the parameter, type of biochar, contaminant source, and soil and soil type) the toxic effect to F. candida, and decreased the toxicity of leachates to V. fischeri.

  11. Effect of steam activated biochar application to industrially contaminated soils on bioavailability of polycyclic aromatic hydrocarbons and ecotoxicity of soils.

    PubMed

    Kołtowski, Michał; Hilber, Isabel; Bucheli, Thomas D; Oleszczuk, Patryk

    2016-10-01

    The aim of this study was to determine the effect of steam activation of biochars on the immobilization of freely dissolved (Cfree) and bioaccessible fraction (Cbioacc) of PAHs in soils. Additionally, the toxicity to various organisms like Vibrio fischeri, Lepidium sativum and Folsomia candida was measured before and after the amendment of biochars to soils. Three biochars produced from willow, coconut and wheat straw were steam activated and added to three different soils with varying content and origin of PAHs (coke vs. bitumen). The soils with the addition of the biochars (activated and non-activated) were incubated for a period of 60days. Steam activation of the biochars resulted in more pronounced reduction of both Cfree and Cbioacc. The range of the increase in effectiveness was from 10 to 84% for Cfree and from 50 to 99% for Cbioacc. In contrast, the effect of activation on the toxicity of the soils studied varied greatly and was specific to a particular test and soil type. Essentially, biochar activation did not result in a change of phytotoxicity, but it increased or decreased (depending on the parameter, type of biochar, contaminant source, and soil and soil type) the toxic effect to F. candida, and decreased the toxicity of leachates to V. fischeri. PMID:27267727

  12. Biodegradation of Aromatic Compounds by Escherichia coli

    PubMed Central

    Díaz, Eduardo; Ferrández, Abel; Prieto, María A.; García, José L.

    2001-01-01

    Although Escherichia coli has long been recognized as the best-understood living organism, little was known about its abilities to use aromatic compounds as sole carbon and energy sources. This review gives an extensive overview of the current knowledge of the catabolism of aromatic compounds by E. coli. After giving a general overview of the aromatic compounds that E. coli strains encounter and mineralize in the different habitats that they colonize, we provide an up-to-date status report on the genes and proteins involved in the catabolism of such compounds, namely, several aromatic acids (phenylacetic acid, 3- and 4-hydroxyphenylacetic acid, phenylpropionic acid, 3-hydroxyphenylpropionic acid, and 3-hydroxycinnamic acid) and amines (phenylethylamine, tyramine, and dopamine). Other enzymatic activities acting on aromatic compounds in E. coli are also reviewed and evaluated. The review also reflects the present impact of genomic research and how the analysis of the whole E. coli genome reveals novel aromatic catabolic functions. Moreover, evolutionary considerations derived from sequence comparisons between the aromatic catabolic clusters of E. coli and homologous clusters from an increasing number of bacteria are also discussed. The recent progress in the understanding of the fundamentals that govern the degradation of aromatic compounds in E. coli makes this bacterium a very useful model system to decipher biochemical, genetic, evolutionary, and ecological aspects of the catabolism of such compounds. In the last part of the review, we discuss strategies and concepts to metabolically engineer E. coli to suit specific needs for biodegradation and biotransformation of aromatics and we provide several examples based on selected studies. Finally, conclusions derived from this review may serve as a lead for future research and applications. PMID:11729263

  13. APPLICATION OF TOXICITY-BASED FRACTIONATION TECHNIQUES AND STRUCTURE-ACTIVITY RELATIONSHIP MODELS FOR THE IDENTIFICATION OF PHOTOTOXIC POLYCYCLIC AROMATIC HYDROCARBONS IN SEDIMENT PORE WATER

    EPA Science Inventory

    Studies conducted in our laboratory show that sediments contaminated with complex mixtures of polycyclic aromatic hydrocarbons (PAHs) can exhibit enhanced toxicity (lethality) to a variety of aquatic species when the samples are tested under ultarviolet (UV) light designed to mim...

  14. Nematicidal activity of essential oils and volatiles derived from Portuguese aromatic flora against the pinewood nematode, Bursaphelenchus xylophilus.

    PubMed

    Barbosa, P; Lima, A S; Vieira, P; Dias, L S; Tinoco, M T; Barroso, J G; Pedro, L G; Figueiredo, A C; Mota, M

    2010-03-01

    Twenty seven essential oils, isolated from plants representing 11 families of Portuguese flora, were screened for their nematicidal activity against the pinewood nematode (PWN), Bursaphelenchus xylophilus. The essential oils were isolated by hydrodistillation and the volatiles by distillation-extraction, and both were analysed by GC and GC-MS. High nematicidal activity was achieved with essential oils from Chamaespartium tridentatum, Origanum vulgare, Satureja montana, Thymbra capitata, and Thymus caespititius. All of these essential oils had an estimated minimum inhibitory concentration ranging between 0.097 and 0.374 mg/ml and a lethal concentration necessary to kill 100% of the population (LC(100)) between 0.858 and 1.984 mg/ml. Good nematicidal activity was also obtained with the essential oil from Cymbopogon citratus. The dominant components of the effective oils were 1-octen-3-ol (9%), n-nonanal, and linalool (both 7%) in C. tridentatum, geranial (43%), neral (29%), and β-myrcene (25%) in C. citratus, carvacrol (36% and 39%), γ-terpinene (24% and 40%), and p-cymene (14% and 7%) in O. vulgare and S. montana, respectively, and carvacrol (75% and 65%, respectively) in T. capitata and T. caespititius. The other essential oils obtained from Portuguese flora yielded weak or no activity. Five essential oils with nematicidal activity against PWN are reported for the first time. PMID:22736831

  15. Nematicidal activity of essential oils and volatiles derived from Portuguese aromatic flora against the pinewood nematode, Bursaphelenchus xylophilus

    PubMed Central

    Barbosa, P.; Lima, A. S.; Vieira, P.; Dias, L. S.; Tinoco, M. T.; Barroso, J. G.; Pedro, L. G.; Figueiredo, A. C.

    2010-01-01

    Twenty seven essential oils, isolated from plants representing 11 families of Portuguese flora, were screened for their nematicidal activity against the pinewood nematode (PWN), Bursaphelenchus xylophilus. The essential oils were isolated by hydrodistillation and the volatiles by distillation-extraction, and both were analysed by GC and GC-MS. High nematicidal activity was achieved with essential oils from Chamaespartium tridentatum, Origanum vulgare, Satureja montana, Thymbra capitata, and Thymus caespititius. All of these essential oils had an estimated minimum inhibitory concentration ranging between 0.097 and 0.374 mg/ml and a lethal concentration necessary to kill 100% of the population (LC100) between 0.858 and 1.984 mg/ml. Good nematicidal activity was also obtained with the essential oil from Cymbopogon citratus. The dominant components of the effective oils were 1–octen-3-ol (9%), n–nonanal, and linalool (both 7%) in C. tridentatum, geranial (43%), neral (29%), and β-myrcene (25%) in C. citratus, carvacrol (36% and 39%), γ-terpinene (24% and 40%), and p-cymene (14% and 7%) in O. vulgare and S. montana, respectively, and carvacrol (75% and 65%, respectively) in T. capitata and T. caespititius. The other essential oils obtained from Portuguese flora yielded weak or no activity. Five essential oils with nematicidal activity against PWN are reported for the first time. PMID:22736831

  16. Fruits and vegetables protect against the genotoxicity of heterocyclic aromatic amines activated by human xenobiotic-metabolizing enzymes expressed in immortal mammalian cells.

    PubMed

    Platt, K L; Edenharder, R; Aderhold, S; Muckel, E; Glatt, H

    2010-12-21

    Heterocyclic aromatic amines (HAAs) can be formed during the cooking of meat and fish at elevated temperatures and are associated with an increased risk for cancer. On the other hand, epidemiological findings suggest that foods rich in fruits and vegetables can protect against cancer. In the present study three teas, two wines, and the juices of 15 fruits and 11 vegetables were investigated for their protective effect against the genotoxic effects of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). To closely mimic the enzymatic activation of these HAAs in humans, genetically engineered V79 Chinese hamster fibroblasts were employed that express human cytochrome P450-dependent monooxygenase (hCYP) 1A2 (responsible for the first step of enzymatic activation) and human N(O)-acetyltransferase (hNAT) 2*4 or human sulfotransferase (hSULT)1A1*1 (responsible for the second step of enzymatic activation): V79-hCYP1A2-hNAT2*4 for IQ activation and V79-hCYP1A2-hSULT1A1*1 for PhIP activation. HAA genotoxicity was determined by use of the comet assay. Black, green and rooibos tea moderately reduced the genotoxicity of IQ (IC(50)=0.8-0.9%), whereas red and white wine were less active. From the fruit juices, sweet cherry juice exhibited the highest inhibitory effect on IQ genotoxicity (IC(50)=0.17%), followed by juices from kiwi fruit, plum and blueberry (IC(50)=0.48-0.71%). The juices from watermelon, blackberry, strawberry, black currant, and Red delicious apple showed moderate suppression, whereas sour cherry, grapefruit, red currant, and pineapple juices were only weakly active. Granny Smith apple juice and orange juice proved inactive. Of the vegetable juices, strong inhibition of IQ genotoxicity was only seen with spinach and onion juices (IC(50)=0.42-0.54%). Broccoli, cauliflower, beetroot, sweet pepper, tomato, chard, and red-cabbage juices suppressed IQ genotoxicity only moderately, whereas cucumber juice was

  17. Activation of electrophilicity of stable Y-delocalized carbamate cations in intramolecular aromatic substitution reaction: evidence for formation of diprotonated carbamates leading to generation of isocyanates.

    PubMed

    Kurouchi, Hiroaki; Kawamoto, Kyoko; Sugimoto, Hiromichi; Nakamura, Satoshi; Otani, Yuko; Ohwada, Tomohiko

    2012-10-19

    Although cations with three heteroatoms, such as monoprotonated guanidine and urea, are stabilized by Y-shaped conjugation and such Y-conjugated cations are sufficiently basic to be further protonated (or protosolvated) to dications in strongly acid media, only O-monoprotonated species have been detected in the case of carbamates even in magic acid. We found that the trifluoromethanesulfonic acid-catalyzed cyclization of arylethylcarbamates proceeds to afford dihydroisoquinolones in high yield. In strong acids, methyl carbamates are fully O-monoprotonated, and these monocations do not undergo cyclization even under heating. But, as the acidity of the reaction medium is further increased, the cyclization reaction of methyl phenethylcarbamates starts to proceed as a first-order reaction, with a linear relationship between rate and acidity. The sign and magnitude of the entropy of activation ΔS(‡) were found to be similar to those of other A(Ac)1 reactions. These results strongly support the idea that further protonation of the O-protonated carbamates is involved in the cyclization, but the concentration of the dications is very low and suggests that the rate-determining step is dissociation of methanol from the diprotonated carbamate to generate protonated isocyanate, which reacts with the aromatic ring. Therefore, O-protonated carbamates are weak bases in sharp contrast to other Y-shaped monocations.

  18. Responses of mixtures of polyhalogenated aromatic compounds or single compounds in the CALUX-assay a novel species-specific bioassay for Ah-receptor active compounds

    SciTech Connect

    Murk, A.J.; Aarts, J.M.M.J.G.; Jonas, A.; Brouwer, A.; Denison, M.S.

    1995-12-31

    Polyhalogenated aromatic hydrocarbons (PHAHs) elicit a number of common toxic responses, including reproductive toxicity, teratogenicity, impairment of immune responses, alterations in vitamin A and thyroid hormone metabolism and carcinogenesis. The toxic effects however are highly dependent on the animal species used, The most toxic PHAHs are approximate isostereomeres of 2,3,7,8 tetrachlorinated dibenzo-p-dioxin (TCDD) and share a common mechanism of action mediated by the aryl hydrocarbon receptor (AhR). Based on the common receptor mediated mechanism, the toxic equivalency factor concept was developed, in which the potency of each individual congener is expressed relative to TCDD, thus allowing hazard and risk assessment for mixtures of PHAHs. A number of recombinant cell lines were developed, including hepalclc7 mouse and H4IIE rat hepatoma cell lines, with AhR-mediated firefly (Photinus pyralis) luciferase gene expression. The response in this so-called CALUX (chemical activated luciferase expression) assay is additive for polychlorinated dibenzofurans (PCDFs) and PCDDS, but for polychlorinated biphenyls (PCBs) both synergistic and antagonistic interactions have been demonstrated, which are partially species-dependent. Also some structurally related compounds, like polybrominated diphenyl ether, pentachlorinated phenol, benzo(a)pyrene, pyrene, tetrachlorobenzyltoluene (Ugilec 141) and mixtures of polychlorinated terphenyls have been tested in the CALUX assay. The responses of these compounds were sometimes agonistic, but also antagonistic and synergistic effects on the TCDO response were observed.

  19. Coordinating activation strategy for C(sp(3))-H/C(sp(3))-H cross-coupling to access β-aromatic α-amino acids.

    PubMed

    Li, Kaizhi; Wu, Qian; Lan, Jingbo; You, Jingsong

    2015-01-01

    The past decade has witnessed significant advances in C-H bond functionalizations with the discovery of new mechanisms. Non-precious transition-metal-catalysed radical oxidative coupling for C(sp(3))-H bond transformations is an appealing strategy for C-C bond formations. The radical oxidative C(sp(3))-H/C(sp(3))-H cross-coupling reactions of α-C(sp(3))-H bonds of amines with free radicals represent a conceptual and practical challenge. We herein develop the coordinating activation strategy to illustrate the nickel-catalysed radical oxidative cross-coupling between C(sp(3))-H bonds and (hetero)arylmethyl free radicals. The protocol can tolerate a rich variety of α-amino acids and (hetero)arylmethanes as well as arylmethylenes and arylmethines, affording a large library of α-tertiary and α-quaternary β-aromatic α-amino acids. This process also features low-cost metal catalyst, readily handled and easily removable coordinating group, synthetic simplicity and gram-scale production, which would enable the potential for economical production at commercial scale in the future. PMID:26415985

  20. Removal of Aromatic Pollutant Surrogate from Water by Recyclable Magnetite-Activated Carbon Nanocomposite: An Experiment for General Chemistry

    ERIC Educational Resources Information Center

    Furlan, Ping Y.; Melcer, Michael E.

    2014-01-01

    A general chemistry laboratory experiment using readily available chemicals is described to introduce college students to an exciting class of nanocomposite materials. In a one-step room temperature synthetic process, magnetite nanoparticles are embedded onto activated carbon matrix. The resultant nanocomposite has been shown to combine the…

  1. Nucleophilic fluorination of aromatic compounds

    DOEpatents

    Satyamurthy, Nagichettiar; Barrio, Jorge R

    2014-03-18

    Iodylbenzene derivatives substituted with electron donating as well as electron withdrawing groups on the aromatic ring are used as precursors in aromatic nucleophilic substitution reactions. The iodyl group (IO.sub.2) is regiospecifically substituted by nucleophilic fluoride to provide the corresponding fluoroaryl derivatives. No-carrier-added [F-18]fluoride ion derived from anhydrous [F-18](F/Kryptofix, [F-18]CsF or a quaternary ammonium fluoride (e.g., Me.sub.4NF, Et.sub.4NF, n-Bu.sub.4NF, (PhCH.sub.2).sub.4NF) exclusively substitutes the iodyl moiety in these derivatives and provides high specific activity F-18 labeled fluoroaryl analogs. Iodyl derivatives of a benzothiazole analog and 6-iodyl-L-dopa derivatives have been synthesized as precursors and have been used in the preparation of no-carrier-added [F-18]fluorobenzothiazole as well as 6-[F-18]fluoro-L-dopa.

  2. Fate of iron and polycyclic aromatic hydrocarbons during the remediation of a contaminated soil using iron-activated persulfate: A column study.

    PubMed

    Pardo, F; Santos, A; Romero, A

    2016-10-01

    Remediation of contaminated soils under flow-through conditions is an issue of great interest since it provides a better approach to real case applications than batch experiments. In this work, a column filled with soil, artificially spiked and aged for three months with Phenanthrene (PHE), Anthracene (ANT), Pyrene (PYR) and Benzo(a)pyrene (BaP), was treated for 25days with persulfate (PS) activated by Fe(3+) and nanoparticles of zerovalent iron (nZVI). Effects of type of iron fed into the column (Fe(3+) or nZVI) and nZVI concentration were studied. PS inlet concentration was 0.2mmolcm(-3) and residence time in the column was close to 1.72days. Iron, PS and polycyclic aromatic hydrocarbons (PAHs) concentration, as well as pH, were monitored during treatment. Concentration profiles of iron and PAHs were observed along the column, with higher iron concentrations and higher PAHs removal efficiencies in the closest sections to the column entrance. BaP and ANT were completely depleted regardless the conditions used, but PHE and PYR showed higher resistance to oxidation, achieving near a 90% removal in the closest sections to the injection source in all runs, but decreasing significantly with column length. Besides, natural degradation of ANT resulted in the formation 9.10-anthraquinone (ATQ), an oxy-PAH which showed higher resistance than PHE and PYR. Although higher PAHs removal efficiencies were achieved when nZVI was used as activator, only a moderate improvement was noticed when the highest concentration of nZVI was used as a consequence of radical scavenging by an excess of Fe(2+). Finally, a kinetic model based on runs performed in batch, from a previous work, was able to predict the experimental average concentrations of PAHs in the column when Fe(3+) was used as activator.

  3. Fate of iron and polycyclic aromatic hydrocarbons during the remediation of a contaminated soil using iron-activated persulfate: A column study.

    PubMed

    Pardo, F; Santos, A; Romero, A

    2016-10-01

    Remediation of contaminated soils under flow-through conditions is an issue of great interest since it provides a better approach to real case applications than batch experiments. In this work, a column filled with soil, artificially spiked and aged for three months with Phenanthrene (PHE), Anthracene (ANT), Pyrene (PYR) and Benzo(a)pyrene (BaP), was treated for 25days with persulfate (PS) activated by Fe(3+) and nanoparticles of zerovalent iron (nZVI). Effects of type of iron fed into the column (Fe(3+) or nZVI) and nZVI concentration were studied. PS inlet concentration was 0.2mmolcm(-3) and residence time in the column was close to 1.72days. Iron, PS and polycyclic aromatic hydrocarbons (PAHs) concentration, as well as pH, were monitored during treatment. Concentration profiles of iron and PAHs were observed along the column, with higher iron concentrations and higher PAHs removal efficiencies in the closest sections to the column entrance. BaP and ANT were completely depleted regardless the conditions used, but PHE and PYR showed higher resistance to oxidation, achieving near a 90% removal in the closest sections to the injection source in all runs, but decreasing significantly with column length. Besides, natural degradation of ANT resulted in the formation 9.10-anthraquinone (ATQ), an oxy-PAH which showed higher resistance than PHE and PYR. Although higher PAHs removal efficiencies were achieved when nZVI was used as activator, only a moderate improvement was noticed when the highest concentration of nZVI was used as a consequence of radical scavenging by an excess of Fe(2+). Finally, a kinetic model based on runs performed in batch, from a previous work, was able to predict the experimental average concentrations of PAHs in the column when Fe(3+) was used as activator. PMID:27235898

  4. Crystal structure and geometry-optimization study of 4-methyl-3‧,5‧-dinitro-4‧-methyl benzylidene aniline

    NASA Astrophysics Data System (ADS)

    Yu, Wei; Yang, Li; Zhang, Tong-lai; Zhang, Jian-guo; Ren, Fu-jian; Liu, Yan-hong; Wu, Rui-feng; Guo, Jin-yu

    2006-08-01

    Schiff base 4-methyl-3',5'-dinitro-4'-methyl benzylidene aniline was synthesized by the condensation of 4-amino-2,6-dinitrotoluene with 4-methylbenzaldehyde. The crystal of the title compound was obtained and it was characterized by X-ray single crystal diffraction analysis, EA, FTIR and 1H NMR. The geometry and normal vibrations have been obtained from the density functional theory (DFT) method with the B3LYP method employing the 6-31G** and 6-311G** basis sets. The calculated results propose that the latter is more accurate to the experimental data. The structural parameters from the theory are close to those of the crystal, and the computational frequencies are in agreement with the experimental data.

  5. 4,10-Dinitro-2,6,8,12-tetraoxa-4,10-diazatetracyclo[5.5.0.05,903,11]dodecane Synthesis

    NASA Astrophysics Data System (ADS)

    Maksimowski, Paweł; Gołofit, Tomasz

    2013-07-01

    4,10-Dinitro-2,6,8,12-tetraoxa-4,10-diazatetracyclo[5.5.0.05,903,11]dodecane (TEX) was obtained by nitrolysis of 1,4-diformyl-2,3,5,6-tetrahydroxypiperazine reaction using a mixture of fuming nitric acid and concentrated sulfuric acid. The optimal process temperature was 54-56°C. The yield of the synthesis depends inter alia on the rate the reactants are introduced into the reaction medium and on the time of conditioning of the reaction mixture. A maximal yield of ca. 40% was achieved at the reactant addition time of 2 h and conditioning time of 2 h. None of the other nitrating mixtures examined proved superior to the conventional nitrating mixture. The product was examined by high-performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), and differential scanning calorimetry (DSC) techniques and the results are reported.

  6. Comparative Study of Composition, Antioxidant, and Antimicrobial Activities of Essential Oils of Selected Aromatic Plants from Balkan Peninsula.

    PubMed

    Stanković, Nemanja; Mihajilov-Krstev, Tatjana; Zlatković, Bojan; Matejić, Jelena; Stankov Jovanović, Vesna; Kocić, Branislava; Čomić, Ljiljana

    2016-05-01

    The objective of the present study to perform a comparative analysis of the chemical composition, antioxidant, and antimicrobial activities of the essential oils of plant species Hyssopus officinalis, Achillea grandifolia, Achillea crithmifolia, Tanacetum parthenium, Laserpitium latifolium, and Artemisia absinthium from Balkan Peninsula. The chemical analysis of essential oils was performed by using gas chromatography and gas chromatography-mass spectrometry. Monoterpenes were dominant among the recorded components, with camphor in T. parthenium, A. grandifolia, and A. crithmifolia (51.4, 45.4, and 25.4 %, respectively), 1,8-cineole in H. officinalis, A. grandifolia, and A. crithmifolia (49.1, 16.4, and 14.8 %, respectively), and sabinene in L. latifolium and A. absinthium (47.8 and 21.5 %). The antiradical and antioxidant activities were determined by using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) and 2,2-diphenyl-1-picrylhydrazyl radical scavenging methods. The essential oil of A. grandifolia has shown the highest antioxidant activity [IC50 of 33.575 ± 0.069 mg/mL for 2,2-diphenyl-1-picrylhydrazyl and 2.510 ± 0.036 mg vitamin C/g for the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) assay]. The antimicrobial activity against 16 multiresistant pathogenic bacteria isolated from human source material was tested by the broth microdilution assay. The resulting minimum inhibitory concentration/minimum bactericidal concentration values ranged from 4.72 to 93.2 mg/mL. Therefore, the essential oils of the plant species included in this study may be considered to be prospective natural sources of antimicrobial substances, and may contribute as effective agents in the battle against bacterial multiresistance. PMID:26891001

  7. Comparative Study of Composition, Antioxidant, and Antimicrobial Activities of Essential Oils of Selected Aromatic Plants from Balkan Peninsula.

    PubMed

    Stanković, Nemanja; Mihajilov-Krstev, Tatjana; Zlatković, Bojan; Matejić, Jelena; Stankov Jovanović, Vesna; Kocić, Branislava; Čomić, Ljiljana

    2016-05-01

    The objective of the present study to perform a comparative analysis of the chemical composition, antioxidant, and antimicrobial activities of the essential oils of plant species Hyssopus officinalis, Achillea grandifolia, Achillea crithmifolia, Tanacetum parthenium, Laserpitium latifolium, and Artemisia absinthium from Balkan Peninsula. The chemical analysis of essential oils was performed by using gas chromatography and gas chromatography-mass spectrometry. Monoterpenes were dominant among the recorded components, with camphor in T. parthenium, A. grandifolia, and A. crithmifolia (51.4, 45.4, and 25.4 %, respectively), 1,8-cineole in H. officinalis, A. grandifolia, and A. crithmifolia (49.1, 16.4, and 14.8 %, respectively), and sabinene in L. latifolium and A. absinthium (47.8 and 21.5 %). The antiradical and antioxidant activities were determined by using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) and 2,2-diphenyl-1-picrylhydrazyl radical scavenging methods. The essential oil of A. grandifolia has shown the highest antioxidant activity [IC50 of 33.575 ± 0.069 mg/mL for 2,2-diphenyl-1-picrylhydrazyl and 2.510 ± 0.036 mg vitamin C/g for the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) assay]. The antimicrobial activity against 16 multiresistant pathogenic bacteria isolated from human source material was tested by the broth microdilution assay. The resulting minimum inhibitory concentration/minimum bactericidal concentration values ranged from 4.72 to 93.2 mg/mL. Therefore, the essential oils of the plant species included in this study may be considered to be prospective natural sources of antimicrobial substances, and may contribute as effective agents in the battle against bacterial multiresistance.

  8. Constituents and Pharmacological Activities of Myrcia (Myrtaceae): A Review of an Aromatic and Medicinal Group of Plants

    PubMed Central

    Cascaes, Márcia Moraes; Guilhon, Giselle Maria Skelding Pinheiro; Andrade, Eloisa Helena de Aguiar; Zoghbi, Maria das Graças Bichara; Santos, Lourivaldo da Silva

    2015-01-01

    Myrcia is one of the largest genera of the economically important family Myrtaceae. Some of the species are used in folk medicine, such as a group known as “pedra-hume-caá” or “pedra-ume-caá” or “insulina vegetal” (insulin plant) that it is used for the treatment of diabetes. The species are an important source of essential oils, and most of the chemical studies on Myrcia describe the chemical composition of the essential oils, in which mono- and sesquiterpenes are predominant. The non-volatile compounds isolated from Myrcia are usually flavonoids, tannins, acetophenone derivatives and triterpenes. Anti-inflammatory, antinociceptive, antioxidant, antimicrobial activities have been described to Myrcia essential oils, while hypoglycemic, anti-hemorrhagic and antioxidant activities were attributed to the extracts. Flavonoid glucosides and acetophenone derivatives showed aldose reductase and α-glucosidase inhibition, and could explain the traditional use of Myrcia species to treat diabetes. Antimicrobial and anti-inflammatory are some of the activities observed for other isolated compounds from Myrcia. PMID:26473832

  9. Molten salt-supported polycondensation of optically active diacid monomers with an aromatic thiazole-bearing diamine using microwave irradiation.

    PubMed

    Mallakpour, Shadpour; Zadehnazari, Amin

    2014-05-01

    Microwave heating was used to prepare optically active thiazole-bearing poly(amide-imide)s. Polymerization reactions were carried out in the molten tetrabutylammonium bromide as a green molten salt medium and triphenyl phosphite as the homogenizer. Structural elucidation of the compounds was performed by Fourier transform infrared and NMR spectroscopic data and elemental analysis results. The polymeric samples were readily soluble in various organic solvents, forming low-colored and flexible thin films via solution casting. They showed high thermal stability with decomposition temperature being above 360 °C. They were assembled randomly in a nanoscale size.

  10. Molten salt-supported polycondensation of optically active diacid monomers with an aromatic thiazole-bearing diamine using microwave irradiation

    PubMed Central

    Mallakpour, Shadpour; Zadehnazari, Amin

    2013-01-01

    Microwave heating was used to prepare optically active thiazole-bearing poly(amide-imide)s. Polymerization reactions were carried out in the molten tetrabutylammonium bromide as a green molten salt medium and triphenyl phosphite as the homogenizer. Structural elucidation of the compounds was performed by Fourier transform infrared and NMR spectroscopic data and elemental analysis results. The polymeric samples were readily soluble in various organic solvents, forming low-colored and flexible thin films via solution casting. They showed high thermal stability with decomposition temperature being above 360 °C. They were assembled randomly in a nanoscale size. PMID:25685498

  11. Synergistic liquid-liquid extractive spectrophotometric determination of gold(III) using 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol.

    PubMed

    Kamble, Ganesh S; Kolekar, Sanjay S; Han, Sung H; Anuse, Mansing A

    2010-05-15

    Synergistic liquid-liquid extractive spectrophotometric determination of gold(III) using 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydro pyrimidine-2-thiol [2',4'-dinitro APTPT] has been described. Equal volumes (5cm(3)) of the 2',4'-dinitro APTPT (0.02molL(-1)) in the presence of pyridine (0.5molL(-1)) form an orange-red coloured ternary complex with gold(III) of molar ratio 1:1:1 at pH 1.8-2.4 with 5min of shaking. The absorbance of coloured organic layer in 1,2-dichloroethane is measured spectrophotometrically at 445nm against reagent blank. A pronounced synergism has been observed by the binary mixture of 2',4'-dinitro APTPT and pyridine, which shows that the enhancement in the absorbance is observed in the presence of pyridine by the adduct formation in the organic phase. Beer's law was obeyed in the concentration range 2.5-20.0microgmL(-1), with molar absorptivity and Sandell's sensitivity values of 8.7x10(3)dm(3)mol(-1)cm(-1) and 0.023microgcm(-2) respectively. A repetition of the method was checked by finding relative standard deviation (R.S.D.) (n=10) which was 0.17%. The composition of the gold(III)-2',4'-dinitro APTPT-pyridine adduct was established by slope analysis, molar ratio and Job's method. The ternary complex was stable for more than 48h. The influence of various factors such as pH, 2',4'-dinitro APTPT concentration, solvent and pyridine on the degree of complexation has been established. A number of foreign ions tested for their interferences and use of suitable masking agents wherever necessary are tabulated, which show that selectivity of the method has been enhanced. The method is successfully employed for the determination of gold(III) in binary, synthetic mixtures and ayurvedic samples. The reliability of the method is assured by inter-comparison of experimental values, using an atomic absorption spectrometer. PMID:20298898

  12. Trimerization of aromatic nitriles

    NASA Technical Reports Server (NTRS)

    Hsu, L. C. (Inventor)

    1977-01-01

    Triazine compounds and cross-linked polymer compositions were made by heating aromatic nitriles to a temperature in the range of about 100 C to about 700 C, in the presence of a catalyst or mixture of catalysts. Aromatic nitrile-modified (terminated and/or appended) imide, benzimidazole, imidazopyrrolone, quinoxaline, and other condensation type prepolymers or their precopolymers were made which were trimerized with or without a filler by the aforementioned catalytic trimerization process.

  13. Highly Active and Specific Tyrosine Ammonia-Lyases from Diverse Origins Enable Enhanced Production of Aromatic Compounds in Bacteria and Saccharomyces cerevisiae

    PubMed Central

    Stahlhut, Steen Gustav; Li, Mingji; Gaspar, Paula; Siedler, Solvej; Förster, Jochen; Maury, Jérôme; Borodina, Irina

    2015-01-01

    Phenylalanine and tyrosine ammonia-lyases form cinnamic acid and p-coumaric acid, which are precursors of a wide range of aromatic compounds of biotechnological interest. Lack of highly active and specific tyrosine ammonia-lyases has previously been a limitation in metabolic engineering approaches. We therefore identified 22 sequences in silico using synteny information and aiming for sequence divergence. We performed a comparative in vivo study, expressing the genes intracellularly in bacteria and yeast. When produced heterologously, some enzymes resulted in significantly higher production of p-coumaric acid in several different industrially important production organisms. Three novel enzymes were found to have activity exclusively for phenylalanine, including an enzyme from the low-GC Gram-positive bacterium Brevibacillus laterosporus, a bacterial-type enzyme from the amoeba Dictyostelium discoideum, and a phenylalanine ammonia-lyase from the moss Physcomitrella patens (producing 230 μM cinnamic acid per unit of optical density at 600 nm [OD600]) in the medium using Escherichia coli as the heterologous host). Novel tyrosine ammonia-lyases having higher reported substrate specificity than previously characterized enzymes were also identified. Enzymes from Herpetosiphon aurantiacus and Flavobacterium johnsoniae resulted in high production of p-coumaric acid in Escherichia coli (producing 440 μM p-coumaric acid OD600 unit−1 in the medium) and in Lactococcus lactis. The enzymes were also efficient in Saccharomyces cerevisiae, where p-coumaric acid accumulation was improved 5-fold over that in strains expressing previously characterized tyrosine ammonia-lyases. PMID:25911487

  14. Accumulation of halogenated aromatic hydrocarbons and activities of cytochrome P450 and glutathione S-transferase in crabs (Eriocheir japonicus) from Japanese rivers

    SciTech Connect

    Ishizuka, Mayumi; Iwata, Hisato; Kazusaka, Akio; Fujita, Shoichi; Sakiyama, Takanori; Fukushima, Minoru

    1998-08-01

    The hepatopancreases of freshwater crabs (Eriocheir japonicus) collected from three Japanese rivers were analyzed for planar halogenated aromatic hydrocarbons (HAHs), including polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and coplanar polychlorinated biphenyls (PCBs). The hepatic glutathione S-transferase (GST)-dependent enzyme activities in the crab hepatopancreas were also measured to examine their potential as biomarkers for the contaminants. Crabs from the Tone River, which runs through industrial, agricultural, and urban areas, have the highest concentrations of HAHs (4,100 pg/g fat weight), followed by those from the Barato River (2,430--2,970 pg/g fat weight), whereas crabs from the Shiribetsu River were relatively less contaminated (1,350--1,800 pg/g fat weight). Identification and numerous PCDD and PCDF congeners in crabs from the Barato and Shiribetsu Rivers were notably contaminated with 1,3,6,8- and 1,3,7,9-TeCDD congeners, which suggests that a possible source was chlornitrofen, which has been extensively used in paddy fields as a herbicide. Calculation of 2,3,7,8-tetrachlorinated dibenzo-p-dioxin toxic equivalents (TEQs) showed that the causal contaminants of higher TEQs in crabs from the Tone River (94.7 TEQ picograms per gram fat weight) were PCDDs and PCDFs, although the most important contributor to the total TEQs was coplanar PCBs (49.95%). The crab hepatopancreas appeared to have abilities to transfer glutathione to 1-chloro-2,4-nitrobenzene (CDNB) and 3,4-dichloronitrobenzene (DCNB). The crabs with the highest TEQ levels showed the highest GST activities.

  15. Aromatic Polyimide Foam

    NASA Technical Reports Server (NTRS)

    Weiser, Erik S. (Inventor); St.Clair, Terry L. (Inventor); Echigo, Yoshiaki (Inventor); Kaneshiro, Hisayasu (Inventor)

    2000-01-01

    A mechanically undensified aromatic polyimide foam is made from an aromatic polyimide precursor solid residuum and has the following combination of properties: a density according to ASTM D-3574A of about 0.5 pounds/cu.ft to about 20 pounds/cu.ft; a compression strength according to ASTM D-3574C of about 1.5 psi to about 1500 psi; and a limiting oxygen index according to ASTM D-2863 of about 35% oxygen to about 75% oxygen at atmospheric pressure. The aromatic polyimide foam has no appreciable solid inorganic contaminants which are residues of inorganic blowing agents. The aromatic polyimide which constitutes the aromatic polyimide foam has a glass transition temperature (Tg) by differential scanning calorimetry of about 235 C to about 400 C; and a thermal stability of 0 to about 1% weight loss at 204 C as determined by thermogravinietric analysis (TGA). The aromatic polyimide foam has utility as foam insulation and as structural foam, for example, for aeronautical, aerospace and maritime applications.

  16. Ultrahigh Gas Storage both at Low and High Pressures in KOH-Activated Carbonized Porous Aromatic Frameworks

    PubMed Central

    Li, Yanqiang; Ben, Teng; Zhang, Bingyao; Fu, Yao; Qiu, Shilun

    2013-01-01

    The carbonized PAF-1 derivatives formed by high-temperature KOH activation showed a unique bimodal microporous structure located at 0.6 nm and 1.2 nm and high surface area. These robust micropores were confirmed by nitrogen sorption experiment and high-resolution transmission electron microscopy (TEM). Carbon dioxide, methane and hydrogen sorption experiments indicated that these novel porous carbon materials have significant gas sorption abilities in both low-pressure and high-pressure environments. Moreover the methane storage ability of K-PAF-1-750 is among the best at 35 bars, and its low-pressure gas adsorption abilities are also comparable to the best porous materials in the world. Combined with excellent physicochemical stability, these materials are very promising for industrial applications such as carbon dioxide capture and high-density clean energy storage. PMID:23939301

  17. Inhibition of the mutagenicity of bay-region diol epoxides of polycyclic aromatic hydrocarbons by naturally occurring plant phenols: Exceptional activity of ellagic acid

    PubMed Central

    Wood, Alexander W.; Huang, Mou-Tuan; Chang, Richard L.; Newmark, Harold L.; Lehr, Roland E.; Yagi, Haruhiko; Sayer, Jane M.; Jerina, Donald M.; Conney, Allan H.

    1982-01-01

    concentrations of ellagic acid are needed to inhibit the mutagenic activity of the chemically less reactive bay-region diol epoxides of benz[a]anthracene, chrysene, and benzo[c]phenanthrene. These studies demonstrate that ellagic acid is a potent antagonist of the adverse biological effects of the ultimate carcinogenic metabolites of several polycyclic aromatic hydrocarbons and suggest that this naturally occurring plant phenol, normally ingested by humans, may inhibit the carcinogenicity of polycyclic aromatic hydrocarbons. PMID:6752950

  18. Interaction of W-Substituted Analogs of Cyclo-RRRWFW with Bacterial Lipopolysaccharides: the Role of the Aromatic Cluster in Antimicrobial Activity ▿ †

    PubMed Central

    Bagheri, Mojtaba; Keller, Sandro; Dathe, Margitta

    2011-01-01

    The activity of cyclo-RRRWFW (c-WFW) against Escherichia coli has been shown to be modulated by the aromatic motif and the lipopolysaccharides (LPS) in the bacterial outer membrane. To identify interaction sites and to elucidate the mode of c-WFW action, peptides were synthesized by the replacement of tryptophan (W) with analogs having altered hydrophobicity, dipole and quadrupole moments, hydrogen-bonding ability, amphipathicity, and ring size. The peptide activity against Bacillus subtilis and erythrocytes increased with increasing hydrophobicity, whereas the effect on E. coli revealed a more complex pattern. Although they had no effect on the E. coli inner membrane even at concentrations higher than the MIC, peptides permeabilized the outer membrane according to their antimicrobial activity pattern, suggesting a major role of LPS in peptide transport across the wall. For isothermal titration calorimetry (ITC) studies of peptide-lipid bilayer interaction, we used POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-choline), either alone or in mixtures with 1-palmitoyl-2-oleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (POPG), to mimic the charge properties of eukaryotic and bacterial membranes, respectively, as well as in mixtures with lipid A, rough LPS, and smooth LPS as models of the outer membrane of E. coli. Peptide accumulation was determined by both electrostatic and hydrophobic interactions. The susceptibility of the lipid systems followed the order of POPC-smooth LPS >> POPC-rough LPS > POPC-lipid A = POPC-POPG > POPC. Low peptide hydrophobicity and enhanced flexibility reduced binding. The influence of the other properties on the free energy of partitioning was low, but an enhanced hydrogen-bonding ability and dipole moment resulted in remarkable variations in the contribution of enthalpy and entropy. In the presence of rough and smooth LPS, the binding-modulating role of these parameters decreased. The highly differentiated activity pattern against E. coli

  19. Diversity of organotrophic bacteria, activity of dehydrogenases and urease as well as seed germination and root growth Lepidium sativum, Sorghum saccharatum and Sinapis alba under the influence of polycyclic aromatic hydrocarbons.

    PubMed

    Lipińska, Aneta; Wyszkowska, Jadwiga; Kucharski, Jan

    2015-12-01

    Polycyclic aromatic hydrocarbons are organic compounds with highly toxic, carcinogenic, and mutagenic properties, which adversely affect the basic biological parameters of the soil, including the count of microorganisms, and the enzymatic activity. In addition to disturbances to the biological activity of the soil, PAHs may also exhibit toxic effects on plants. In view of the above, the study involved testing aimed at the determination of the effects of polycyclic aromatic hydrocarbons in a form of naphthalene, phenanthrene, anthracene and pyrene on the count, colony development (CD) index, ecophysiological (EP) diversity index of organotrophic bacteria, and the activity of soil dehydrogenases and soil urease. Moreover, an attempt was made to determine the soil's resistance based on the activity of the above-listed enzymes, and the effect of polycyclic aromatic hydrocarbons on seed germination and root growth was assessed by Lepidium sativum, Sorghum saccharatum, and Sinapis alba. In addition, the species of bacteria found in a soil subjected to strong pressure of polycyclic aromatic hydrocarbons were isolated. The experiment was performed in a laboratory on samples of loamy sand. Polycyclic aromatic hydrocarbons were introduced into the soil in an amount of 0, 1000, 2000, and 4000 mg kg(-1) of soil dry matter. Germination and growth of cress (L. sativum), white mustard (S. alba), and sweet sorghum (S. saccharatum) were determined using Phytotoxkit tests. It was found that the tested PAHs increased the average colony counts of organotrophic soil bacteria; pyrene did so to the greatest extent (2.2-fold relative to non-contaminated soil), phenanthrene to the smallest extent (1.4-fold relative to non-contaminated soil). None of the PAHs changed the value of the bacterial colony development (CD) index, while anthracene and pyrene increased the value of the eco-physiological (EP) diversity indicator. PAHs lowered the activity of the tested enzymes. The activity of

  20. Diversity of organotrophic bacteria, activity of dehydrogenases and urease as well as seed germination and root growth Lepidium sativum, Sorghum saccharatum and Sinapis alba under the influence of polycyclic aromatic hydrocarbons.

    PubMed

    Lipińska, Aneta; Wyszkowska, Jadwiga; Kucharski, Jan

    2015-12-01

    Polycyclic aromatic hydrocarbons are organic compounds with highly toxic, carcinogenic, and mutagenic properties, which adversely affect the basic biological parameters of the soil, including the count of microorganisms, and the enzymatic activity. In addition to disturbances to the biological activity of the soil, PAHs may also exhibit toxic effects on plants. In view of the above, the study involved testing aimed at the determination of the effects of polycyclic aromatic hydrocarbons in a form of naphthalene, phenanthrene, anthracene and pyrene on the count, colony development (CD) index, ecophysiological (EP) diversity index of organotrophic bacteria, and the activity of soil dehydrogenases and soil urease. Moreover, an attempt was made to determine the soil's resistance based on the activity of the above-listed enzymes, and the effect of polycyclic aromatic hydrocarbons on seed germination and root growth was assessed by Lepidium sativum, Sorghum saccharatum, and Sinapis alba. In addition, the species of bacteria found in a soil subjected to strong pressure of polycyclic aromatic hydrocarbons were isolated. The experiment was performed in a laboratory on samples of loamy sand. Polycyclic aromatic hydrocarbons were introduced into the soil in an amount of 0, 1000, 2000, and 4000 mg kg(-1) of soil dry matter. Germination and growth of cress (L. sativum), white mustard (S. alba), and sweet sorghum (S. saccharatum) were determined using Phytotoxkit tests. It was found that the tested PAHs increased the average colony counts of organotrophic soil bacteria; pyrene did so to the greatest extent (2.2-fold relative to non-contaminated soil), phenanthrene to the smallest extent (1.4-fold relative to non-contaminated soil). None of the PAHs changed the value of the bacterial colony development (CD) index, while anthracene and pyrene increased the value of the eco-physiological (EP) diversity indicator. PAHs lowered the activity of the tested enzymes. The activity of

  1. Impact of salinity and dispersed oil on adsorption of dissolved aromatic hydrocarbons by activated carbon and organoclay.

    PubMed

    Younker, Jessica M; Walsh, Margaret E

    2015-12-15

    Adsorption capacity of phenol and naphthalene by powdered activated carbon (PAC), a commercial organoclay (OC) and a lab synthesized organoclay (BTMA) was studied using batch adsorption experiments under variable feed water quality conditions including single- and multi- solute conditions, fresh water, saline water and oily-and-saline water. Increasing salinity levels was found to reduce adsorption capacity of OC, likely due to destabilization, aggregation and subsequent removal of organoclay from the water column, but did not negatively impact adsorption capacity of PAC or BTMA. Increased dispersed oil concentrations were found to reduce the surface area of all adsorbents. This decreased the adsorption capacity of PAC for both phenol and naphthalene, and reduced BTMA adsorption of phenol, but did not negatively affect naphthalene removals by either organoclay. The presence of naphthalene as a co-solute significantly reduced phenol adsorption by PAC, but had no impact on organoclay adsorption. These results indicated that adsorption by PAC occurred via a surface adsorption mechanism, while organoclay adsorption occurred by hydrophobic or pi electron interactions. In general, PAC was more sensitive to changes in water quality than either of the organoclays evaluated in this study. However, PAC exhibited a higher adsorption capacity for phenol and naphthalene compared to both organoclays even in adverse water quality conditions. PMID:26259095

  2. Purification of aromatic hydrocarbons via fibrous activated carbon/photocatalytic composite coupled with UV light-emitting diodes.

    PubMed

    Jo, Wan-Kuen

    2013-01-01

    In the present study, the applicability of light-emitting diodes (LEDs) to a fibrous activated carbon (FAC)/titania (TiO2) composite used for the purification of gas-phase benzene, toluene, ethyl benzene and xylene was evaluated. The surface and morphological properties of the FAC and prepared FAC/TiO2 composite were investigated by X-ray diffraction and scanning electron microscopy. The study protocol included two different tests, comparison of FAC and the FAC/TiO2 composite for BTEX removal efficiency and evaluation of the FAC/TiO2 composite for benzene and toluene removal efficiency under differing operation conditions. The time-series ratios obtained with the FAC/TiO2 composite showed longer removal times for all target compounds when compared to those of FAC alone. For both benzene and toluene, the breakthrough time decreased with the stream flow rate, whereas it increased with increasing light intensity under the experimental conditions employed in this study. The breakthrough time of benzene and toluene increased as increasing amounts of TiO2 were coated onto the surface of FAC between 11 and 229 mg-TiO2 (g-FAC)(-1), but decreased as the amount of TiO2 increased to 451 mg (g-FAC)(-1). These findings indicate that the optimal TiO2 weight for the removal process of benzene and toluene via the FAC/TiO2 composite is between 229 and 451 mg-TiO2 (g-FAC)(-1).

  3. Aromaticity and Antiaromaticity in Transition-Metal Systems

    SciTech Connect

    Zubarev, Dmitry Y.; Averkiev, Boris B.; Zhai, Hua Jin; Wang, Lai S.; Boldyrev, Alexander I.

    2007-11-05

    Aromaticity is an important concept in chemistry primarily for hydrocarbon compounds, but it has been extended to compounds containing transition-metal atoms. Recent findings of aromaticity and antiaromaticy in all-metal clusters have stimulated further researches in describing the chemical bonding, structures, and stability in transition-metal clusters and compounds on the basis of aromaticity and antiaromaticity, which are reviewed here. The presence of d-orbitals endows much more diverse chemistry, structure, and chemical bonding to transition-metal clusters and compounds. One interesting feature is the existence of a new type of δ-aromaticity, in addition to σ- and π-aromaticity that are only possible for main group compounds. Another striking characteristic in the chemical bonding of transition-metal systems is the multi-fold nature of aromaticity, antiaromaticity, or even conflicting aromaticity. Separate sets of counting rules have been proposed for cyclic transition-metal systems to account for the three types of σ-, π-, and δ-aromaticity/antiaromaticity. The diverse transition-metal clusters and compounds reviewed here indicate that multiple aromaticity and antiaromaticity may be much more common in chemistry than one would anticipate. It is hoped that the current review will stimulate interest in further understanding the structure and bonding, on the basis of aromaticity and antiaromaticity, of other known or unknown transition-metal systems, such as the active sites of enzymes or other biomolecules, which contain transition-metal atoms and clusters.

  4. Rapid microwave hydrothermal synthesis of ZnGa{sub 2}O{sub 4} with high photocatalytic activity toward aromatic compounds in air and dyes in liquid water

    SciTech Connect

    Sun Meng; Li Danzhen; Zhang Wenjuan; Chen Zhixin; Huang Hanjie; Li Wenjuan; He Yunhui; Fu Xianzhi

    2012-06-15

    ZnGa{sub 2}O{sub 4} was synthesized from Ga(NO{sub 3}){sub 3} and ZnCl{sub 2} via a rapid and facile microwave-assisted hydrothermal method. The photocatalytic properties of the as-prepared ZnGa{sub 2}O{sub 4} were evaluated by the degradation of pollutants in air and aqueous solution under ultraviolet (UV) light illumination. The results demonstrated that ZnGa{sub 2}O{sub 4} had exhibited efficient photocatalytic activities higher than that of commercial P25 (Degussa Co.) in the degradation of benzene, toluene, and ethylbenzene, respectively. In the liquid phase degradation of dyes (methyl orange, Rhodamine B, and methylene blue), ZnGa{sub 2}O{sub 4} has also exhibited remarkable activities higher than that of P25. After 32 min of UV light irradiation, the decomposition ratio of methyl orange (10 ppm, 150 mL) over ZnGa{sub 2}O{sub 4} (0.06 g) was up to 99%. The TOC tests revealed that the mineralization ratio of MO (10 ppm, 150 mL) was 88.1% after 90 min of reaction. A possible mechanism of the photocatalysis over ZnGa{sub 2}O{sub 4} was also proposed. - Graphical abstract: In the degradation of RhB under UV light irradiation, ZnGa{sub 2}O{sub 4} had exhibited efficient photo-activity, and after only 24 min of irradiation the decomposition ratio was up to 99.8%. Highlights: Black-Right-Pointing-Pointer A rapid and facile M-H method to synthesize ZnGa{sub 2}O{sub 4} photocatalyst. Black-Right-Pointing-Pointer The photocatalyst exhibits high activity toward benzene and dyes. Black-Right-Pointing-Pointer The catalyst possesses more surface hydroxyl sites than TiO{sub 2} (P25). Black-Right-Pointing-Pointer Deep oxidation of different aromatic compounds and dyes over catalyst.

  5. Aromatic amines and cancer.

    PubMed

    Vineis, P; Pirastu, R

    1997-05-01

    Epidemiological evidence on the relation between aromatic amines and cancer risk is reviewed. In particular, cancer risk in humans resulting from exposure to aromatic amines from occupational sources and tobacco smoking is assessed with reference to ecologic, cohort, and case-control studies. Seven arylamines have been classified by the International Agency for Research on Cancer: benzidine-based dyes and MOCA (4,4'-methylene bis 2-choloroaniline) were considered 'probably' carcinogenic, Group 2A, because of a high level of evidence in experimental animals; two occupational chemicals (2-naphthylamine and benzidine), one drug (Chlornaphazine), and two manufacturing processes (manufacture of auramine and magenta) were included in Group 1 on the basis of 'sufficient' evidence of carcinogenicity in humans. Occupational exposures to aromatic amines explain up to 25 percent of bladder cancers in some areas of Western countries; these estimates might be higher in limited areas of developing countries. Aromatic amines contaminate the ambient air as a component of environmental tobacco smoke. There is increasing evidence that the excess of bladder cancer in smokers is attributable to aromatic amines rather than to other contaminants of tobacco smoke such as polycyclic aromatic hydrocarbons (PAH). A modulating role in the risk of bladder cancer associated with exposure to aromatic amines is played by metabolic polymorphisms, such as the N-acetyltransferase genotype, raising important social and ethical issues. The consistent observation of a difference between men and women in bladder cancer risk, after allowing for known risk factors, suggests consideration of gender-related biological determinants for future investigation.

  6. Illumina MiSeq Sequencing Reveals Diverse Microbial Communities of Activated Sludge Systems Stimulated by Different Aromatics for Indigo Biosynthesis from Indole.

    PubMed

    Zhang, Xuwang; Qu, Yuanyuan; Ma, Qiao; Zhang, Zhaojing; Li, Duanxing; Wang, Jingwei; Shen, Wenli; Shen, E; Zhou, Jiti

    2015-01-01

    Indole, as a typical N-heteroaromatic compound existed in coking wastewater, can be used for bio-indigo production. The microbial production of indigo from indole has been widely reported during the last decades using culture-dependent methods, but few studies have been carried out by microbial communities. Herein, three activated sludge systems stimulated by different aromatics, i.e. naphthalene plus indole (G1), phenol plus indole (G2) and indole only (G3), were constructed for indigo production from indole. During the operation, G1 produced the highest indigo yield in the early stage, but it switched to G3 in the late stage. Based on LC-MS analysis, indigo was the major product in G1 and G3, while the purple product 2-(7-oxo-1H-indol-6(7H)-ylidene) indolin-3-one was dominant in G2. Illumina MiSeq sequencing of 16S rRNA gene amplicons was applied to analyze the microbial community structure and composition. Detrended correspondence analysis (DCA) and dissimilarity tests showed that the overall community structures of three groups changed significantly during the operation (P<0.05). Nevertheless, the bacteria assigned to phylum Proteobacteria, family Comamonadaceae, and genera Diaphorobacter, Comamonas and Aquamicrobium were commonly shared dominant populations. Pearson correlations were calculated to discern the relationship between microbial communities and indigo yields. The typical indigo-producing populations Comamonas and Pseudomonas showed no positive correlations with indigo yields, while there emerged many other genera that exhibited positive relationships, such as Aquamicrobium, Truepera and Pusillimonas, which had not been reported for indigo production previously. The present study should provide new insights into indigo bio-production by microbial communities from indole.

  7. Bioaccumulation of native polycyclic aromatic hydrocarbons from sediment by a polychaete and a gastropod: freely dissolved concentrations and activated carbon amendment.

    PubMed

    Cornelissen, Gerard; Breedveld, Gijs D; Naes, Kristoffer; Oen, Amy M P; Ruus, Anders

    2006-09-01

    The present paper describes a study on the bioaccumulation of native polycyclic aromatic hydrocarbons (PAHs) from three harbors in Norway using the polychaete Nereis diversicolor and the gastropod Hinia reticulata. First, biota-sediment accumulation factors (BSAFs) were measured in laboratory bioassays using the original sediments. Median BSAFs were 0.004 to 0.01 kg organic carbon/kg lipid (10 PAHs and 6 organism-sediment combinations), which was a factor of 89 to 240 below the theoretical BSAF based on total sediment contents (which is approximately one). However, if BSAFs were calculated on the basis of measured freely dissolved PAH concentrations in the pore water (measured with polyoxymethylene passive samplers), it appeared that these BSAFfree values agreed well with the measured BSAFs, within a factor of 1.7 to 4.3 (median values for 10 PAHs and six organism-sediment combinations). This means that for bioaccumulation, freely dissolved pore-water concentrations appear to be a much better measure than total sediment contents. Second, we tested the effect of 2% (of sediment dry wt) activated carbon (AC) amendments on BSAE The BSAFs were significantly reduced by a factor of six to seven for N. diversicolor in two sediments (i.e., two of six organism-sediment combinations), whereas no significant reduction was observed for H. reticulata. This implies that either site-specific evaluations of AC amendment are necessary, using several site-relevant benthic organisms, or that the physiology of H. reticulata caused artifactually high BSAF values in the presence of AC.

  8. Mechanistic quantitative structure-activity relationship model for the photoinduced toxicity of polycyclic aromatic hydrocarbons. 1: Physical model based on chemical kinetics in a two-compartment system

    SciTech Connect

    Krylov, S.N.; Huang, X.D.; Zeiler, L.F.; Dixon, D.G.; Greenberg, B.M.

    1997-11-01

    A quantitative structure-activity relationship model for the photoinduced toxicity of 16 polycyclic aromatic hydrocarbons (PAHs) to duckweed (Lemna gibba) in simulated solar radiation (SSR) was developed. Lemna gibba was chosen for this study because toxicity could be considered in two compartments: water column and leaf tissue. Modeling of photoinduced toxicity was described by photochemical reactions between PAHs and a hypothetical group of endogenous biomolecules (G) required for normal growth, with damage to G by PAHs and/or photomodified PAHs in SSR resulting in impaired growth. The reaction scheme includes photomodification of PAHs, uptake of PAHs into leaves, triplet-state formation of intact PAHs, photosensitization reactions that damage G, and reactions between photomodified PAHs and G. The assumptions used were: the PAH photomodification rate is slower than uptake of chemicals into leaves, the PAH concentration in aqueous solution is nearly constant during a toxicity test, the fluence rate of actinic radiation is lower within leaves than in the aqueous phase, and the toxicity of intact PAHs in the dark is negligible. A series of differential equations describing the reaction kinetics of intact and photomodifed PAHs with G was derived. The resulting equation for PAH toxicity was a function of treatment period, initial PAH concentration, relative absorbance of SSR by each PAH, quantum yield for formation of triplet-state PAH, and rate of PAH photomodification. Data for growth in the presence of intact and photomodified PAHs were used to empirically solve for a photosensitization constant (PSC) and a photomodification constant (PMC) for each of the 16 PAHs tested. For 9 PAHs the PMC dominates and for 7 PAHs the PSC dominates.

  9. Illumina MiSeq Sequencing Reveals Diverse Microbial Communities of Activated Sludge Systems Stimulated by Different Aromatics for Indigo Biosynthesis from Indole

    PubMed Central

    Zhang, Xuwang; Qu, Yuanyuan; Ma, Qiao; Zhang, Zhaojing; Li, Duanxing; Wang, Jingwei; Shen, Wenli; Shen, E; Zhou, Jiti

    2015-01-01

    Indole, as a typical N-heteroaromatic compound existed in coking wastewater, can be used for bio-indigo production. The microbial production of indigo from indole has been widely reported during the last decades using culture-dependent methods, but few studies have been carried out by microbial communities. Herein, three activated sludge systems stimulated by different aromatics, i.e. naphthalene plus indole (G1), phenol plus indole (G2) and indole only (G3), were constructed for indigo production from indole. During the operation, G1 produced the highest indigo yield in the early stage, but it switched to G3 in the late stage. Based on LC-MS analysis, indigo was the major product in G1 and G3, while the purple product 2-(7-oxo-1H-indol-6(7H)-ylidene) indolin-3-one was dominant in G2. Illumina MiSeq sequencing of 16S rRNA gene amplicons was applied to analyze the microbial community structure and composition. Detrended correspondence analysis (DCA) and dissimilarity tests showed that the overall community structures of three groups changed significantly during the operation (P<0.05). Nevertheless, the bacteria assigned to phylum Proteobacteria, family Comamonadaceae, and genera Diaphorobacter, Comamonas and Aquamicrobium were commonly shared dominant populations. Pearson correlations were calculated to discern the relationship between microbial communities and indigo yields. The typical indigo-producing populations Comamonas and Pseudomonas showed no positive correlations with indigo yields, while there emerged many other genera that exhibited positive relationships, such as Aquamicrobium, Truepera and Pusillimonas, which had not been reported for indigo production previously. The present study should provide new insights into indigo bio-production by microbial communities from indole. PMID:25928424

  10. The aromatic ene reaction

    PubMed Central

    Niu, Dawen; Hoye, Thomas R.

    2014-01-01

    The ene reaction is a pericyclic process in which an alkene having an allylic hydrogen atom (the ene donor) reacts with a second unsaturated species (the enophile) to form a new product with a transposed π-bond. The aromatic ene reaction, in which the alkene component is embedded in an aromatic ring, has only been reported in a few (four) instances and has proceeded in low yield (≤6%). Here we show efficient aromatic ene reactions in which a thermally generated aryne engages a pendant m-alkylarene substituent to produce a dearomatized isotoluene, itself another versatile but rare reactive intermediate. Our experiments were guided by computational studies that revealed structural features conducive to the aromatic ene process. We proceeded to identify a cascade comprising three reactions: (i) hexadehydro-Diels-Alder (for aryne generation), (ii) intramolecular aromatic ene, and (iii) bimolecular Alder ene. The power of this cascade is evident from the structural complexity of the final products, the considerable scope, and the overall efficiency of these multi-stage, reagent- and byproduct-free, single-pot transformations. PMID:24345944

  11. Synergistic extraction and spectrophotometric determination of copper(II) using 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol: analysis of alloys, pharmaceuticals and biological samples.

    PubMed

    Kamble, Ganesh S; Kolekar, Sanjay S; Anuse, Mansing A

    2011-05-01

    A simple and selective spectrophotometric method was developed for the determination of copper(II) with 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol [2',4'-dinitro APTPT] as a chromogenic reagent. The procedure was based on the synergistic extraction of copper(II) with 2',4'-dinitro APTPT in the presence of 0.5 mol L(-1) pyridine to give green colored ternary complex of a molar ratio 1:2:2 (M:L:Py) in the pH range 8.7-10.5. It exhibits a maximum absorption of colored complex at 445 nm and 645 nm in chloroform against the reagent blank. Beer's law was followed in the concentration range 10-80 μg mL(-1) of copper(II) and optimum range of 20-70 μg mL(-1) the metal as evaluated from Ringbom's plot. The molar absorptivity and Sandell's sensitivity of copper(II)-2',4'-dinitro APTPT-pyridine complex in chloroform are 0.87×10(3) L mol(-1)c m(-1) and 0.072 μg cm(-2), respectively. The interfering effects of various cations and anions were also studied, and use of suitable masking agents enhances the selectivity of the method. The proposed method is rapid, reproducible and successfully applied for the determination of copper(II) in binary and synthetic mixtures, alloys, pharmaceutical formulations, environmental and fertilizer samples. Comparison of the results with those obtained using an atomic absorption spectrophotometer also tested the validity of the method. PMID:21330190

  12. Synergistic extraction and spectrophotometric determination of copper(II) using 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol: Analysis of alloys, pharmaceuticals and biological samples

    NASA Astrophysics Data System (ADS)

    Kamble, Ganesh S.; Kolekar, Sanjay S.; Anuse, Mansing A.

    2011-05-01

    A simple and selective spectrophotometric method was developed for the determination of copper(II) with 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol [2',4'-dinitro APTPT] as a chromogenic reagent. The procedure was based on the synergistic extraction of copper(II) with 2',4'-dinitro APTPT in the presence of 0.5 mol L -1 pyridine to give green colored ternary complex of a molar ratio 1:2:2 (M:L:Py) in the pH range 8.7-10.5. It exhibits a maximum absorption of colored complex at 445 nm and 645 nm in chloroform against the reagent blank. Beer's law was followed in the concentration range 10-80 μg mL -1 of copper(II) and optimum range of 20-70 μg mL -1 the metal as evaluated from Ringbom's plot. The molar absorptivity and Sandell's sensitivity of copper(II)-2',4'-dinitro APTPT-pyridine complex in chloroform are 0.87 × 10 3 L mol -1 cm -1 and 0.072 μg cm -2, respectively. The interfering effects of various cations and anions were also studied, and use of suitable masking agents enhances the selectivity of the method. The proposed method is rapid, reproducible and successfully applied for the determination of copper(II) in binary and synthetic mixtures, alloys, pharmaceutical formulations, environmental and fertilizer samples. Comparison of the results with those obtained using an atomic absorption spectrophotometer also tested the validity of the method.

  13. Magnetic criteria of aromaticity.

    PubMed

    Gershoni-Poranne, Renana; Stanger, Amnon

    2015-09-21

    This review describes the current state of magnetic criteria of aromaticity. The introduction contains the fundamentals of ring currents in aromatic and antiaromatic systems, followed by a brief description of experimental and computational tools: NMR, diamagnetic susceptibility exaltation, current density analyses (CDA) and nucleus independent chemical shifts (NICS). This is followed by more comprehensive chapters: NMR - focusing on the work of R. Mitchell - NICS and CDA - describing the progress and development of the methods to their current state and presenting some examples of representative work. PMID:26035305

  14. Magnetic criteria of aromaticity.

    PubMed

    Gershoni-Poranne, Renana; Stanger, Amnon

    2015-09-21

    This review describes the current state of magnetic criteria of aromaticity. The introduction contains the fundamentals of ring currents in aromatic and antiaromatic systems, followed by a brief description of experimental and computational tools: NMR, diamagnetic susceptibility exaltation, current density analyses (CDA) and nucleus independent chemical shifts (NICS). This is followed by more comprehensive chapters: NMR - focusing on the work of R. Mitchell - NICS and CDA - describing the progress and development of the methods to their current state and presenting some examples of representative work.

  15. Relaxed specificity in aromatic prenyltransferases.

    PubMed

    Koehl, Patrice

    2005-07-01

    Prenylation represent a critical step in the biosynthesis of many natural products, A new study reveals how aromatic prenyltransferase enzymes tolerate diverse aromatic polyketides while still controlling the length of prenyl side chains.

  16. Sorption and degradation of petroleum hydrocarbons, polycyclic aromatic hydrocarbons, alkylphenols, bisphenol A and phthalates in landfill leachate using sand, activated carbon and peat filters.

    PubMed

    Kalmykova, Yuliya; Moona, Nashita; Strömvall, Ann-Margret; Björklund, Karin

    2014-06-01

    Landfill leachates are repeatedly found contaminated with organic pollutants, such as alkylphenols (APs), phthalates and polycyclic aromatic hydrocarbons (PAHs) at levels exceeding water quality standards. It has been shown that these pollutants may be present in the colloidal and truly dissolved phase in contaminated water, making particle separation an inefficient removal method. The aim of this study was to investigate sorption and degradation of petroleum hydrocarbons (PHCs), selected APs, bisphenol A (BPA), phthalates and PAHs from landfill leachate using sand, granulated activated carbon (GAC) and peat moss filters. A pilot plant was installed at an inactive landfill with mixed industrial and household waste and samples were collected before and after each filter during two years. Leachate pre-treated in oil separator and sedimentation pond failed to meet water quality standards in most samples and little improvement was seen after the sand filter. These techniques are based on particle removal, whereas the analysed pollutants are found, to varying degrees, bound to colloids or dissolved. However, even highly hydrophobic compounds expected to be particle-bound, such as the PHCs and high-molecular weight PAHs, were poorly removed in the sand filter. The APs and BPA were completely removed by the GAC filter, while mass balance calculations indicate that 50-80% of the investigated phenols were removed in the peat filter. Results suggest possible AP degradation in peat filters. No evidence of phthalate degradation in the landfill, pond or the filters was found. The PHCs were completely removed in 50% and 35% of the measured occasions in the GAC and peat filters, respectively. The opposite trend was seen for removal of PAHs in GAC (50%) and peat (63%). Oxygenated PAHs with high toxicity were found in the leachates but not in the pond sediment. These compounds are likely formed in the pond water, which is alarming because sedimentation ponds are commonly used

  17. Discovery of aromatic components with excellent fragrance properties and biological activities: β-ionols with antimelanogenetic effects and their asymmetric syntheses.

    PubMed

    Komaki, Ryoichi; Ikawa, Takashi; Saito, Kozumo; Hattori, Kazuyo; Ishikawa, Natsuyo; Fukawa, Hidemichi; Egi, Masahiro; Akai, Shuji

    2013-01-01

    Both enantiomers of dihydro-β-ionol and β-ionol, contained in the aromatic components of Osmanthus flower and of Hakuto peach, were obtained with high optical purity by lipase-catalyzed kinetic resolution of the racemates. It was found that all these enantiomers had different characteristic favorable scents and high antimelanogenetic effects. The absolute configuration and the enantiomer ratios of dihydro-β-ionol in the aromatic components of Osmanthus flower and of Hakuto peach were determined. The asymmetric synthesis of (R)-dihydro-β-ionol, one of the most valuable raw materials for fragrance and flavor, was performed from inexpensive β-ionone via lipase-catalyzed dynamic kinetic resolution followed by reduction.

  18. Cr(Salen)-catalyzed addition of 1,3-dichloropropene to aromatic aldehydes. A simple access to optically active vinyl epoxides.

    PubMed

    Bandini, M; Cozzi, P G; Melchiorre, P; Morganti, S; Umani-Ronchi, A

    2001-04-19

    [reaction: see text]. Chiral Cr(Salen) complex (1) prepared in situ from CrCl3 promotes the enantioselective addition of 1,3-dichloropropene to aromatic aldehydes in the presence of Mn as the stoichiometric reductant and Me3SiCl as a scavenger. The resulting 1,2-chlorohydrins obtained in good enantiomeric and diastereoisomeric excesses can be easily transformed into the corresponding chiral vinyl epoxides.

  19. Discovering Chemical Aromaticity Using Fragrant Plants

    ERIC Educational Resources Information Center

    Schneider, Tanya L.

    2010-01-01

    Introductory organic chemistry is often perceived as inaccessible by students. This article describes a method used to link organic chemistry to everyday experience, asking students to explore whether fragrant molecules are also aromatic in the chemical sense. Students were engaged in this activity, excited about their results, and performed well…

  20. Combined Experimental and Theoretical Investigations on Optical Activities of Möbius Aromatic and Möbius Antiaromatic Hexaphyrin Phosphorus Complexes.

    PubMed

    Mori, Tadashi; Tanaka, Takayuki; Higashino, Tomohiro; Yoshida, Kota; Osuka, Atsuhiro

    2016-06-23

    Intrinsically chiral Möbius aromatic [28]hexaphyrin monophosphorus(V) and Möbius antiaromatic [30]hexaphyrin bisphosphorus(V) complexes have been optically resolved and their absolute configurations (ACs) were determined by combined experimental and theoretical investigations on their circular dichroisms (CDs). First elutes in chiral HPLC exhibited strong positive Cotton effects (CEs) at the B-band, characteristic for the ML configurations in their Möbius strips. Weak CEs at the Q-band, if attainable, complemented their AC assignment. The whole CD pattern and intensity were well reproduced by time-dependent approximate coupled cluster theory using model systems that omit five outward meso-aryl substituents (inward-meso-retained model), providing a solid basis for AC assignment. The cost efficient TD-DFT method with appropriate functionals for fully substituted (nontruncated) complexes well reproduced CEs around the B-band (but less satisfactory at the Q-band), also allows the rapid AC estimation for their Möbius strips. Observed difference in CDs between aromatic and antiaromatic hexaphyrins were better interpreted by their shifts in energy levels and altered interactions of relevant molecular orbitals, rather than small differences in Möbius geometries nor aromatic/antiaromatic character, despite the correlations recently claimed in planar π-systems. PMID:27253839

  1. Di(hydroxyphenyl)- benzimidazole monomers

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor); Smith, Joseph G. (Inventor)

    1993-01-01

    Di(hydroxyphenyl)benzimidazole monomers were prepared from phenyl-hydroxybenzoate and aromatic bis(o-diamine)s. These monomers were used in the synthesis of soluble polybenzimidazoles. The reaction involved the aromatic nucleophilic displacement of various di(hydroxyphenyl)benzimidazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds in the presence of an alkali metal base. These polymers exhibited lower glass transition temperatures, improved solubility, and better compression moldability over their commercial counterparts.

  2. Biological transformation pathways of 2,4-dinitro anisole and N-methyl paranitro aniline in anaerobic fluidized-bed bioreactors.

    PubMed

    Platten, William E; Bailey, David; Suidan, Makram T; Maloney, Stephen W

    2010-11-01

    The US Army is evaluating new, insensitive explosives to produce safer munitions. Two potential new components are 2,4-dinitro anisole (DNAN) and N-methyl paranitro aniline (MNA), which would eventually make their way to waste streams generated in the production and handling of new munitions. The effectiveness of anaerobic fluidized-bed bioreactors (AFBB) was studied for treatment and transformation of these two new chemical components in munitions. Each compound was fed into a separate reactor and monitored for removal and transformation, using ethanol as the electron donor. The results show that both were degradable using the AFBB system. DNAN was found to transform into diaminoanisole and MNA was found to transform into N-methyl-p-phenylenediamine. Both of these by-products appeared to form azobond polymers after exposure to air. To test the resilience of the reactors, the compounds were removed from the feed streams for 3 weeks and then reintroduced. DNAN showed that a re-acclimation period was necessary for it to be degraded again, while MNA was removed immediately upon reintroduction. The AFBB technology was shown here to be an effective means of removing the new munitions, but produce secondary compounds that could potentially be just as harmful and require further study.

  3. Integrated reforming/aromatization process

    SciTech Connect

    Harandi, M.N.; Owen, H.

    1990-06-26

    This patent describes an integrated process for increasing the gasoline yield from a catalytic reforming process. It comprises: charging a naphtha boiling range feedstream to a catalytic reforming reaction zone under reforming conversion conditions; withdrawing a reactor effluent stream from the reforming reaction zone; separating the reactor effluent stream into a hydrogen-rich gas stream and an unstabilized reformate stream; further separating the unstabilized reformate in a fractionator into an overhead stream containing C{sub 4} - components and a bottom stream containing C{sub 6} + components; charging the fractionator overhead stream to a catalytic aromatization zone under aromatization conversion conditions; withdrawing an aromatization zone effluent stream from the aromatization zone; cooling the aromatization zone effluent stream; separating the cooled aromatization zone effluent steam into a C{sub 4} - stream and a C{sub 5} + stream; and refluxing the C{sub 5} + aromatic gasoline stream to the fractionation zone.

  4. Dihydrodiol dehydrogenase and polycyclic aromatic hydrocarbon metabolism

    SciTech Connect

    Smithgall, T.E.

    1986-01-01

    Carcinogenic activation of polycyclic aromatic hydrocarbons by microsomal monoxygenases proceeds through trans-dihydrodiol metabolites to diol-epoxide ultimate carcinogens. This thesis directly investigated the role of dihydrodiol dehydrogenase, a cytosolic NAD(P)-linked oxidoreductase, in the detoxification of polycyclic aromatic trans-dihydrodiols. A wide variety of non-K-region trans-dihydrodiols were synthesized and shown to be substrates for the homogeneous rat liver dehydrogenase, including several potent proximate carcinogens derived from 7,12-dimethylbenz(a)anthracene, 5-methylchrysene, and benzo(a)pyrene. Since microsomal activation of polycyclic aromatic hydrocarbons is highly stereospecific, the stereochemical course of enzymatic trans-dihydrodiol oxidation was monitored using circular dichroism spectropolarimetry. The major product formed from the dehydrogenase-catalyzed oxidation of the trans-1,2-dihydrodiol of naphthalene was characterized using UV, IR, NMR, and mass spectroscopy, and appears to be 4-hydroxy-1,2-naphthoquinone. Mass spectral analysis suggests that an analogous hydroxylated o-quinone is formed as the major product of benzo(a)pyrene-7,8-dihydrodiol oxidation. Enzymatic oxidation of trans-dihydrodiols was shown to be potently inhibited by all of the major classes of the nonsteroidal antiinflammatory drugs. Enhancement of trans-dihydrodiol proximate carcinogen oxidation may protect against possible adverse effects of the aspirin-like drugs, and help maintain the balance between activation and detoxification of polycyclic aromatic hydrocarbons.

  5. Birds and polycyclic aromatic hydrocarbons

    USGS Publications Warehouse

    Albers, P.H.

    2006-01-01

    Polycyclic aromatic hydrocarbons (PAH) are present throughout the global environment and are produced naturally and by activities of humans. Effects of PAH on birds have been determined by studies employing egg injection, egg immersion, egg shell application, single and multiple oral doses, subcutaneous injection, and chemical analysis of field-collected eggs and tissue. The four-to six-ring aromatic compounds are the most toxic to embryos, young birds, and adult birds. For embryos, effects include death, developmental abnormalities, and a variety of cellular and biochemical responses. For adult and young birds, effects include reduced egg production and hatching, increased clutch or brood abandonment, reduced growth, increased organweights, and a variety of biochemical responses. Trophic level accumulation is unlikely. Environmental exposure to PAH in areas of high human population or habitats affected by recent petroleum spills might be sufficient to adversely affect reproduction. Evidence of long-term effects of elevated concentrations of environmental PAH on bird populations is very limited and the mechanisms of effect are unclear.

  6. (Hetero)aromatics from dienynes, enediynes and enyne-allenes.

    PubMed

    Raviola, Carlotta; Protti, Stefano; Ravelli, Davide; Fagnoni, Maurizio

    2016-08-01

    The construction of aromatic rings has become a key objective for organic chemists. While several strategies have been developed for the functionalization of pre-formed aromatic rings, the direct construction of an aromatic core starting from polyunsaturated systems is yet a less explored field. The potential of such reactions in the formation of aromatics increased at a regular pace in the last few years. Nowadays, there are reliable and well-established procedures to prepare polyenic derivatives, such as dienynes, enediynes, enyne-allenes and hetero-analogues. This has stimulated their use in the development of innovative cycloaromatizations. Different examples have recently emerged, suggesting large potential of this strategy in the preparation of (hetero)aromatics. Accordingly, this review highlights the recent advancements in this field and describes the different conditions exploited to trigger the process, including thermal and photochemical activation, as well as the use of transition metal catalysis and the addition of electrophiles/nucleophiles or radical species.

  7. Aromaticity Competition in Differentially Fused Borepin-Containing Polycyclic Aromatics.

    PubMed

    Messersmith, Reid E; Siegler, Maxime A; Tovar, John D

    2016-07-01

    This report describes the synthesis and characterization of a series of borepin-based polycyclic aromatics bearing two different arene fusions. The borepin synthesis features streamlined Ti-mediated alkyne reduction, leading to Z-olefins, followed by direct lithiation and borepin formation. These molecules allow for an assessment of aromatic competition between the fused rings and the central borepin core. Crystallographic, magnetic, and computational studies yielded insights about the aromaticity of novel, differentially fused [b,f]borepins and allowed for comparison to literature compounds. Multiple borepin motifs were also incorporated into polycyclic aromatics with five or six rings in the main backbone, and their properties were also evaluated.

  8. Chemical composition and insecticidal activity of essential oils of two aromatic plants from Ivory Coast against Bemisia tabaci G. (Hemiptera: Aleyrodidae).

    PubMed

    Tia, Etienne V; Adima, Augustin A; Niamké, Sébastien L; Jean, Gnago A; Martin, Thibaud; Lozano, Paul; Menut, Chantal

    2011-08-01

    Essential oils of aromatic plants with insecticidal properties are nowadays considered as alternative insecticides to protect cultures from attack by insect pest. The aims of the present work were to evaluate the toxicity of the essential oils vapors of two aromatic plants (Lippia multiflora Mold. and Aframomum latifolium K. Schum) against Bemisia tabaci and to characterize their chemical composition. The highest fumigant toxicity against B. tabaci adults was observed with the L. multiflora oil: by exposure to 0.4 microL/L air, the lethal time inducing 90% mortality (LT90) was below 2 hours for this essential oil whereas it reached 15 h in the case of the A. latifolium oil. Both oils were analyzed by GC-FID and GC-MS on two capillary columns. The oil of L. multiflora contained a majority of oxygenated terpenoids mainly represented by the two acyclic components linalool (46.6%) and (E)-nerolidol (16.5%); the oil of A. latifolium was dominated by hydrocarbonated terpenoids among them beta-pinene (51.6%) and beta-caryophyllene (12.3%) were the two major components.

  9. Peptide aromatic interactions modulated by fluorinated residues: Synthesis, structure and biological activity of Somatostatin analogs containing 3-(3′,5′difluorophenyl)-alanine

    PubMed Central

    Martín-Gago, Pablo; Rol, Álvaro; Todorovski, Toni; Aragón, Eric; Martin-Malpartida, Pau; Verdaguer, Xavier; Vallès Miret, Mariona; Fernández-Carneado, Jimena; Ponsati, Berta; Macias, Maria J.; Riera, Antoni

    2016-01-01

    Somatostatin is a 14-residue peptide hormone that regulates the endocrine system by binding to five G-protein-coupled receptors (SSTR1–5). We have designed six new Somatostatin analogs with L-3-(3′,5′-difluorophenyl)-alanine (Dfp) as a substitute of Phe and studied the effect of an electron-poor aromatic ring in the network of aromatic interactions present in Somatostatin. Replacement of each of the Phe residues (positions 6, 7 and 11) by Dfp and use of a D-Trp8 yielded peptides whose main conformations could be characterized in aqueous solution by NMR. Receptor binding studies revealed that the analog with Dfp at position 7 displayed a remarkable affinity to SSTR2 and SSTR3. Analogs with Dfp at positions 6 or 11 displayed a π-π interaction with the Phe present at 11 or 6, respectively. Interestingly, these analogs, particularly [D-Trp8,L-Dfp11]-SRIF, showed high selectivity towards SSTR2, with a higher value than that of Octreotide and a similar one to that of native Somatostatin. PMID:27271737

  10. Peptide aromatic interactions modulated by fluorinated residues: Synthesis, structure and biological activity of Somatostatin analogs containing 3-(3',5'difluorophenyl)-alanine.

    PubMed

    Martín-Gago, Pablo; Rol, Álvaro; Todorovski, Toni; Aragón, Eric; Martin-Malpartida, Pau; Verdaguer, Xavier; Vallès Miret, Mariona; Fernández-Carneado, Jimena; Ponsati, Berta; Macias, Maria J; Riera, Antoni

    2016-01-01

    Somatostatin is a 14-residue peptide hormone that regulates the endocrine system by binding to five G-protein-coupled receptors (SSTR1-5). We have designed six new Somatostatin analogs with L-3-(3',5'-difluorophenyl)-alanine (Dfp) as a substitute of Phe and studied the effect of an electron-poor aromatic ring in the network of aromatic interactions present in Somatostatin. Replacement of each of the Phe residues (positions 6, 7 and 11) by Dfp and use of a D-Trp8 yielded peptides whose main conformations could be characterized in aqueous solution by NMR. Receptor binding studies revealed that the analog with Dfp at position 7 displayed a remarkable affinity to SSTR2 and SSTR3. Analogs with Dfp at positions 6 or 11 displayed a π-π interaction with the Phe present at 11 or 6, respectively. Interestingly, these analogs, particularly [D-Trp8,L-Dfp11]-SRIF, showed high selectivity towards SSTR2, with a higher value than that of Octreotide and a similar one to that of native Somatostatin. PMID:27271737

  11. Aromatic molecules as spintronic devices

    SciTech Connect

    Ojeda, J. H.; Orellana, P. A.; Laroze, D.

    2014-03-14

    In this paper, we study the spin-dependent electron transport through aromatic molecular chains attached to two semi-infinite leads. We model this system taking into account different geometrical configurations which are all characterized by a tight binding Hamiltonian. Based on the Green's function approach with a Landauer formalism, we find spin-dependent transport in short aromatic molecules by applying external magnetic fields. Additionally, we find that the magnetoresistance of aromatic molecules can reach different values, which are dependent on the variations in the applied magnetic field, length of the molecules, and the interactions between the contacts and the aromatic molecule.

  12. Second molecular hyperpolarizability of 2,2'-diamino-7,7'-dinitro-9,9'- spirobifluorene: An experimental study on third-order nonlinear optical properties of a spiroconjugated dimer

    NASA Astrophysics Data System (ADS)

    Kim, So Yeon; Lee, Minyung; Boo, Bong Hyun

    1998-08-01

    Nonlinear optical properties of a fixed molecular dimer, 2,2'-diamino-7,7'-dinitro9,9'-spirobifluorene (ANSF), have been investigated in solution by the degenerate four-wave mixing technique. It has been observed that the orientationally averaged second molecular hyperpolarizability of ANSF in THF is enhanced ten times in comparison with its monomer unit, 2-amino-7-nitrofluorene. Since electronic coupling between monomer units in ANSF is negligible owing to symmetry, we attribute the large enhancement to the orientational effect of the two constituting dipoles with possible involvement of vibronic coupling and spiroconjugation.

  13. Aromatization of Ethanol Over Desilicated ZSM-5 Zeolites: Effect of Pore Size in the Mesoporous Region.

    PubMed

    Jun, Jong Won; Hasan, Zubair; Kim, Chul-Ung; Jeong, Soon-Yong; Jhung, Sung Hwa

    2016-05-01

    Mesoporous ZSM-5 zeolites were obtained from microporous ZSM-5 by desilication using aqueous NaOH solutions, and their catalytic activity in the aromatization of ethanol was investigated in order to understand the effects of pore size, in the mesoporous region, on the product distribution and stability of the catalysts. Mesopores generally enhanced the selectivities towards aromatics and stability for aromatization. Mesopores with a maximum pore diameter of around 13 nm were the most effective in the aromatization process (especially for benzene and toluene), suggesting that pore-diameter optimization is necessary for efficient catalysis such as aromatization.

  14. Cross-Coupling Reactions of Aromatic and Heteroaromatic Silanolates with Aromatic and Heteroaromatic Halides

    PubMed Central

    Denmark, Scott E.; Smith, Russell C.; Chang, Wen-Tau T.; Muhuhi, Joseck M.

    2009-01-01

    The alkali-metal salts (potassium and sodium) of a large number of aryl- and heteroarylsilanols undergo efficient cross coupling with a wide range of aromatic bromides and chlorides under mild conditions to form polysubstituted biaryls. The critical feature for the success of these coupling reactions and their considerable scope is the use of bis(tri-tert-butylphosphine)palladium. Under the optimized conditions, electron-rich, electron-poor, and sterically hindered arylsilanolates afford cross-coupling products in good yields. Many functional groups are compatible with the coupling conditions such as esters, ketones, acetals, ethers, silyl ethers, and dimethylamino groups. Two particularly challenging substrates, (2-benzofuranyl)dimethylsilanolate and (2,6-dichlorophenyl)dimethylsilanolate prepared as their sodium salts showed excellent activity in the coupling reactions, in the former case also with aromatic chlorides. General methods for the efficient synthesis of a wide range of aromatic silanols are also described. PMID:19199785

  15. A Gene Expression Study of the Activities of Aromatic Ring-Cleavage Dioxygenases in Mycobacterium gilvum PYR-GCK to Changes in Salinity and pH during Pyrene Degradation

    PubMed Central

    Badejo, Abimbola Comfort; Badejo, Adegoke Olugboyega; Shin, Kyung Hoon; Chai, Young Gyu

    2013-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are toxic pollutants found in the environment which can be removed through the use of physical and biological agents. The rate of PAH biodegradation is affected by environmental conditions of pH, salinity and temperature. Adaptation of the pyrene degrading bacteria, Mycobacterium gilvum PYR-GCK, to fluctuating environmental conditions during pyrene biodegrading activity was studied using the quantitative real time – Polymerase Chain Reaction (qRT-PCR) technique. Four aromatic ring-cleavage dioxygenase genes: phdF, phdI, pcaG and pcaH; critical to pyrene biodegradation, were studied in pH states of 5.5, 6.5, 7.5 and NaCl concentrations 0 M, 0.17 M, 0.5 M, 0.6 M, 1 M. First, we conducted a residual pyrene study using gas chromatography and flame ionization technologies. Central to a gene expression study is the use of a valid endogenous reference gene, making its determination our next approach, using the geNorm/NormFinder algorithms. Armed with a valid control gene, rpoB, we applied it to a gene expression study, using the comparative critical threshold (2ΔΔCT) quantification method. The pyrene degrading activity of the strain was strongly functional in all the NaCl concentration states, with the least activity found at 1M (∼70% degraded after 48 hours of cultivation). The transcripts quantification of three genes backed this observation with high expression levels. The gene expression levels also revealed pH 6.5 as optimal for pyrene degradation and weak degradation activity at pH of 5.5, corroborating the residual pyrene analysis. The expression of these genes as proteins has already been studied in our laboratory using proteomics techniques and this validates our current study. PMID:23469141

  16. The first naturally occurring aromatic isothiocyanates, rapalexins A and B, are cruciferous phytoalexins.

    PubMed

    Pedras, M Soledade C; Zheng, Qing-An; Gadagi, Ravi S

    2007-01-28

    The discovery of the first naturally occurring aromatic isothiocyanates, indole-3-isothiocyanates, their first synthesis, antimicrobial activity and proposed biogenetic origin in canola plants are reported.

  17. "Carbo-aromaticity" and novel carbo-aromatic compounds.

    PubMed

    Cocq, Kévin; Lepetit, Christine; Maraval, Valérie; Chauvin, Remi

    2015-09-21

    While the concept of aromaticity is being more and more precisely delineated, the category of "aromatic compounds" is being more and more expanded. This is illustrated by an introductory highlight of the various types of "aromaticity" previously invoked, and by a focus on the recently proposed "aromatic character" of the "two-membered rings" of the acetylene and butatriene molecules. This serves as a general foundation for the definition of "carbo-aromaticity", the relevance of which is surveyed through recent results in the synthetic, physical, and theoretical chemistry of carbo-mers and in particular macrocyclic-polycyclic representatives constituting a natural family of "novel aromatic compounds". With respect to their parent molecules, carbo-mers are constitutionally defined as "carbon-enriched", and can also be functionally regarded as "π-electron-enriched". This is exemplified by recent experimental and theoretical results on functional, aromatic, rigid, σ,π-macrocyclic carbo-benzene archetypes of various substitution patterns, with emphasis on the quadrupolar pattern. For the purpose of comparison, several types of non-aromatic references of carbo-benzenes are then considered, i.e. freely rotating σ,π-acyclic carbo-n-butadienes and flexible σ-cyclic, π-acyclic carbo-cyclohexadienes, and to "pro-aromatic" congeners, i.e. rigid σ,π-macrocyclic carbo-quinoids. It is shown that functional carbo-mers are entering the field of "molecular materials" for properties such as linear or nonlinear optical properties (e.g. dichromism and two-photon absorption) and single molecule conductivity. Since total or partial carbo-mers of aromatic carbon-allotropes of infinite size such as graphene (graphynes and graphdiynes) and graphite ("graphitynes") have long been addressed at the theoretical or conceptual level, recent predictive advances on the electrical, optical and mechanical properties of such carbo-materials are surveyed. Very preliminary experimental results

  18. "Carbo-aromaticity" and novel carbo-aromatic compounds.

    PubMed

    Cocq, Kévin; Lepetit, Christine; Maraval, Valérie; Chauvin, Remi

    2015-09-21

    While the concept of aromaticity is being more and more precisely delineated, the category of "aromatic compounds" is being more and more expanded. This is illustrated by an introductory highlight of the various types of "aromaticity" previously invoked, and by a focus on the recently proposed "aromatic character" of the "two-membered rings" of the acetylene and butatriene molecules. This serves as a general foundation for the definition of "carbo-aromaticity", the relevance of which is surveyed through recent results in the synthetic, physical, and theoretical chemistry of carbo-mers and in particular macrocyclic-polycyclic representatives constituting a natural family of "novel aromatic compounds". With respect to their parent molecules, carbo-mers are constitutionally defined as "carbon-enriched", and can also be functionally regarded as "π-electron-enriched". This is exemplified by recent experimental and theoretical results on functional, aromatic, rigid, σ,π-macrocyclic carbo-benzene archetypes of various substitution patterns, with emphasis on the quadrupolar pattern. For the purpose of comparison, several types of non-aromatic references of carbo-benzenes are then considered, i.e. freely rotating σ,π-acyclic carbo-n-butadienes and flexible σ-cyclic, π-acyclic carbo-cyclohexadienes, and to "pro-aromatic" congeners, i.e. rigid σ,π-macrocyclic carbo-quinoids. It is shown that functional carbo-mers are entering the field of "molecular materials" for properties such as linear or nonlinear optical properties (e.g. dichromism and two-photon absorption) and single molecule conductivity. Since total or partial carbo-mers of aromatic carbon-allotropes of infinite size such as graphene (graphynes and graphdiynes) and graphite ("graphitynes") have long been addressed at the theoretical or conceptual level, recent predictive advances on the electrical, optical and mechanical properties of such carbo-materials are surveyed. Very preliminary experimental results

  19. Electronic Structure Principles and Aromaticity

    ERIC Educational Resources Information Center

    Chattaraj, P. K.; Sarkar, U.; Roy, D. R.

    2007-01-01

    The relationship between aromaticity and stability in molecules on the basis of quantities such as hardness and electrophilicity is explored. The findings reveal that aromatic molecules are less energetic, harder, less polarizable, and less electrophilic as compared to antiaromatic molecules, as expected from the electronic structure principles.

  20. Overview of Polycyclic Aromatic Compounds (PAC)

    PubMed Central

    Achten, Christine; Andersson, Jan T.

    2015-01-01

    The chemical group of polycyclic aromatic compounds (PAC), including the better-known subgroup of polycyclic aromatic hydrocarbons (PAH) and the heterocyclic aromatic compounds (NSO-PAC, heterocycles), comprise several thousand individual compounds. It is hard to find a comprehensive overview in the literature of these PACs that includes a substantial amount of relevant properties. Here an attempt is made to summarize the most studied but also some less well-known PACs. In addition to basic data such as recommended names, abbreviations, CAS numbers, molecular formulas, chemical structures, and exact mono-isotopic molecular weights, physico-chemical properties taken from the literature like boiling points, vapor pressures, water solubilities, Henry's Law constants, n-octanol-water partition coefficients (log KOW), and pKa are summarized. Selected toxicological data are listed indicating carcinogenic and mutagenic activity or effects on different organisms. PAC nomenclature is a complex topic, so suggestions for practical use are made. Regarding available data, estimated (instead of measured) values should be used with caution because considerable deviations from experimentally determined values can occur. For an enhanced understanding of the behavior of single PACs in comparison with each other, some of the properties mentioned above are plotted vs. the number of rings or the degree of alkylation. Also, some physico-chemical data are correlated with different functional groups as substituents of the PAHs. This article reveals that rather little is known about the less common PACs, e.g., higher molecular weight compounds, alkylated or otherwise substituted aromatics, for instance, keto-, oxo-, amino-, nitro-, cyano-PAHs, or some heterocyclic aromatic compounds, including their derivatives. It mirrors the limited state of knowledge about the variety of PACs that do not belong to the 16 EPA PAHs. PMID:26823644

  1. Aromatics saturation over hydrotreating catalysts: Reactivity and susceptibility to poisons

    SciTech Connect

    Kokayeff, P.

    1994-12-31

    Aromatics saturation over hydrotreating catalysts has been investigated by processing a synthetic feedstock to which naphthalene, biphenyl, tetralin, and cyclohexylbenzene have been added as model aromatic compounds. The saturation reactions were successfully correlated with a kinetic model of consecutive first order reactions. The rates of saturation of the di-aromatics, naphthalene and biphenyl, were approximately 5--40 times faster than the rate of saturation of the mono-aromatics, tetralin and cyclohexylbenzene. The nature of the di-aromatic is a significant determinant of its reactivity for saturation. The rate of saturation of naphthalene is 10--20 times faster than the rate of saturation of biphenyl. The two mono-aromatics, tetralin and cyclohexylbenzene, exhibited nearly identical reactivities for saturation. An investigation of the effect of organo-nitrogen compounds on saturation activity revealed a very severe poisoning and attenuation of saturation activity. Since activity was recoverable upon the removal of the poisoning agent the chemical effect was conjectured to be due to adsorption of the poison on the active sites of the catalyst. The adsorption constants were determined for three model nitrogen compounds--quinoline, indole, and tert-butylamine. The poisoning action of an organo-nitrogen compound was found to be dependent on both basicity and chemical structure.

  2. Structural Basis of Substrate Conversion in a New Aromatic Peroxygenase

    PubMed Central

    Piontek, Klaus; Strittmatter, Eric; Ullrich, René; Gröbe, Glenn; Pecyna, Marek J.; Kluge, Martin; Scheibner, Katrin; Hofrichter, Martin; Plattner, Dietmar A.

    2013-01-01

    Aromatic peroxygenases (APOs) represent a unique oxidoreductase sub-subclass of heme proteins with peroxygenase and peroxidase activity and were thus recently assigned a distinct EC classification (EC 1.11.2.1). They catalyze, inter alia, oxyfunctionalization reactions of aromatic and aliphatic hydrocarbons with remarkable regio- and stereoselectivities. When compared with cytochrome P450, APOs appear to be the choice enzymes for oxyfunctionalizations in organic synthesis due to their independence from a cellular environment and their greater chemical versatility. Here, the first two crystal structures of a heavily glycosylated fungal aromatic peroxygenase (AaeAPO) are described. They reveal different pH-dependent ligand binding modes. We model the fitting of various substrates in AaeAPO, illustrating the way the enzyme oxygenates polycyclic aromatic hydrocarbons. Spatial restrictions by a phenylalanine pentad in the active-site environment govern substrate specificity in AaeAPO. PMID:24126915

  3. Extended Corannulenes: Aromatic Bowl/Sheet Hybridization.

    PubMed

    Dutta, Amit K; Linden, Anthony; Zoppi, Laura; Baldridge, Kim K; Siegel, Jay S

    2015-09-01

    Among sheet/sheet polynuclear aromatic hydrocarbon (PAH) hybrids, a buckybowl-graphene hybrid has been used as a model to explore the effects of physical properties of PAHs with distinct planar and bowl regions. Activation of a C(Ar)-F bond was used to synthesize this corannulene/graphenic hybrid. Photophysical and voltammetric studies together with high-level computations revealed curvature and extended π-effects on the properties of these materials. PMID:26216746

  4. Epoxy Coenzyme A Thioester Pathways for Degradation of Aromatic Compounds

    PubMed Central

    Gescher, Johannes

    2012-01-01

    Aromatic compounds (biogenic and anthropogenic) are abundant in the biosphere. Some of them are well-known environmental pollutants. Although the aromatic nucleus is relatively recalcitrant, microorganisms have developed various catabolic routes that enable complete biodegradation of aromatic compounds. The adopted degradation pathways depend on the availability of oxygen. Under oxic conditions, microorganisms utilize oxygen as a cosubstrate to activate and cleave the aromatic ring. In contrast, under anoxic conditions, the aromatic compounds are transformed to coenzyme A (CoA) thioesters followed by energy-consuming reduction of the ring. Eventually, the dearomatized ring is opened via a hydrolytic mechanism. Recently, novel catabolic pathways for the aerobic degradation of aromatic compounds were elucidated that differ significantly from the established catabolic routes. The new pathways were investigated in detail for the aerobic bacterial degradation of benzoate and phenylacetate. In both cases, the pathway is initiated by transforming the substrate to a CoA thioester and all the intermediates are bound by CoA. The subsequent reactions involve epoxidation of the aromatic ring followed by hydrolytic ring cleavage. Here we discuss the novel pathways, with a particular focus on their unique features and occurrence as well as ecological significance. PMID:22582071

  5. Epoxy Coenzyme A Thioester pathways for degradation of aromatic compounds.

    PubMed

    Ismail, Wael; Gescher, Johannes

    2012-08-01

    Aromatic compounds (biogenic and anthropogenic) are abundant in the biosphere. Some of them are well-known environmental pollutants. Although the aromatic nucleus is relatively recalcitrant, microorganisms have developed various catabolic routes that enable complete biodegradation of aromatic compounds. The adopted degradation pathways depend on the availability of oxygen. Under oxic conditions, microorganisms utilize oxygen as a cosubstrate to activate and cleave the aromatic ring. In contrast, under anoxic conditions, the aromatic compounds are transformed to coenzyme A (CoA) thioesters followed by energy-consuming reduction of the ring. Eventually, the dearomatized ring is opened via a hydrolytic mechanism. Recently, novel catabolic pathways for the aerobic degradation of aromatic compounds were elucidated that differ significantly from the established catabolic routes. The new pathways were investigated in detail for the aerobic bacterial degradation of benzoate and phenylacetate. In both cases, the pathway is initiated by transforming the substrate to a CoA thioester and all the intermediates are bound by CoA. The subsequent reactions involve epoxidation of the aromatic ring followed by hydrolytic ring cleavage. Here we discuss the novel pathways, with a particular focus on their unique features and occurrence as well as ecological significance.

  6. Synthesis, and spectroscopic studies of charge transfer complex of 1,2-dimethylimidazole as an electron donor with π-acceptor 2,4-dinitro-1-naphthol in different polar solvents

    NASA Astrophysics Data System (ADS)

    Miyan, Lal; Khan, Ishaat M.; Ahmad, Afaq

    2015-07-01

    The charge transfer (CT) complex of 1,2-dimethylimidazole (DMI) as an electron donor with π acceptor 2,4-dinitro-1-naphthol (DNN) has been studied spectrophotometrically in different solvents like chloroform, acetonitrile, methanol, methylene chloride, etc. at room temperature. The CT complex which is formed through the transfer of lone pair electrons from DMI to DNN exhibits well resolved CT bands and the regions of these bands were remarkably different from those of the donor and acceptor. The stoichiometry of the CT complex was found to be 1:1 by a straight-line method between donor and acceptor with maximum absorption bands. The novel CT complex has been characterized by FTIR, TGA-DTA, powder XRD, 1H NMR and 13C NMR spectroscopic techniques. The Benesi-Hildebrand equation has been used to determine the formation constant (KCT), molar extinction coefficient (εCT), standard gibbs free energy (ΔG°) and other physical parameters of the CT complex. The formation constant recorded higher values and molar extinction coefficient recorded lower values in chloroform compared with methylene chloride, methanol and acetonitrile, confirming the strong interaction between the molecular orbital's of donor and acceptor in the ground state in less polar solvent. This CT complex has been studied by absorption spectra of donor 1,2-dimethylimidazole (DMI) and acceptor 2,4-dinitro-1-naphthol (DNN) by using the spectrophotometric technique in various solvents at room temperature.

  7. N,N-Diethyl­anilinium 5-(2,4-dinitro­phen­yl)-2,6-dioxo-1,2,3,6-tetra­hydro­pyrimidin-4-olate

    PubMed Central

    Kalaivani, Doraisamyraja; Mangaiyarkarasi, Govindan

    2013-01-01

    The asymmetric unit of the title mol­ecular salt, C10H16N+·C10H5N4O7 − (trivial name: N,N-diethyl­anilinium 2,4-dinitro­phenyl­barbiturate), comprises two anion–cation units. In the anions, the dinitro­phenyl ring and the mean plane of the barbiturate ring [planar to within 0.011 (2) and 0.023 (2) Å in the two anions] are inclined to one another by 41.47 (9) and 45.12 (9)°. In the crystal, the anions are linked via strong N—H⋯O hydrogen bonds, forming chains propagating along [10-1]. Within the chains, adjacent inversion-related anionic barbiturate entities are joined through R 2 2(8) ring motifs. The cations are linked to the chains via N—H⋯O hydrogen bonds. The chains are linked via a number of C—H⋯O inter­actions, forming a three-dimensional structure. PMID:23476417

  8. Metabolism and Biomarkers of Heterocyclic Aromatic Amines in Molecular Epidemiology Studies: Lessons Learned from Aromatic Amines

    PubMed Central

    2011-01-01

    Aromatic amines and heterocyclic aromatic amines (HAAs) are structurally related classes of carcinogens that are formed during the combustion of tobacco or during the high-temperature cooking of meats. Both classes of procarcinogens undergo metabolic activation by N-hydroxylation of the exocyclic amine group, to produce a common proposed intermediate, the arylnitrenium ion, which is the critical metabolite implicated in toxicity and DNA damage. However, the biochemistry and chemical properties of these compounds are distinct and different biomarkers of aromatic amines and HAAs have been developed for human biomonitoring studies. Hemoglobin adducts have been extensively used as biomarkers to monitor occupational and environmental exposures to a number of aromatic amines; however, HAAs do not form hemoglobin adducts at appreciable levels and other biomarkers have been sought. A number of epidemiologic studies that have investigated dietary consumption of well-done meat in relation to various tumor sites reported a positive association between cancer risk and well-done meat consumption, although some studies have shown no associations between well-done meat and cancer risk. A major limiting factor in most epidemiological studies is the uncertainty in quantitative estimates of chronic exposure to HAAs and, thus, the association of HAAs formed in cooked meat and cancer risk has been difficult to establish. There is a critical need to establish long-term biomarkers of HAAs that can be implemented in molecular epidemioIogy studies. In this review article, we highlight and contrast the biochemistry of several prototypical carcinogenic aromatic amines and HAAs to which humans are chronically exposed. The biochemical properties and the impact of polymorphisms of the major xenobiotic-metabolizing enzymes on the biological effects of these chemicals are examined. Lastly, the analytical approaches that have been successfully employed to biomonitor aromatic amines and HAAs, and

  9. DNA-damaging activity in vivo and bacterial mutagenicity of sixteen aromatic amines and azo-derivatives, as related quantitatively to their carcinogenicity.

    PubMed

    Parodi, S; Taningher, M; Russo, P; Pala, M; Tamaro, M; Monti-Bragadin, C

    1981-01-01

    Sixteen aromatic amines and azo-derivatives were studied. They were: benzidine; 2-acetylaminofluorene; 3'-methyl-p-dimethylaminobenzene; o-aminoazo-toluene; p-dimethylaminoazobenzene; 2,4-diamino-toluene; 4,4'-oxydianiline; 2,4-diaminoanisole; 4,4'-methylenedianiline; 2-naphthylamine; Auramine O; Rhodamine B; Ponceau MX; 1-naphthylamine; p-aminoazobenzene and aniline. The compounds were examined for their capability to induce alkaline DNA fragmentation in rat liver after treatment in vivo, for their mutagenicity in the Salmonella strains TA 98 and TA 100, for their acute toxicity and for their carcinogenicity in mice and rats. For each parameter a quantitative potency index was established, and the correlation existing amongst the different parameters investigated. Only mutagenicity in the strain TA 98 was slightly correlated with carcinogenic potency (r = 0.408). DNA fragmentation and toxicity were not correlated with carcinogenicity. A significant correlation was found between DNA fragmentation and toxicity (r = 0.539). No correlation was found between DNA fragmentation and mutagenicity. The lack of correlation between DNA fragmentation and carcinogenicity is in contrast with previous results obtained with a family of hydrazine derivatives (12) and a group of nitrosocompounds (22). For these two groups of chemicals correlation between DNA fragmentation and carcinogenicity existed, but not between carcinogenicity and mutagenicity in the Ames' test. It is suggested that short term tests can perform very differently for different classes of chemicals.

  10. Synthesis of aromatic secondary diamines

    NASA Technical Reports Server (NTRS)

    Wolfe, J. F.; Greenwood, T. D.; Kahley, R. A.

    1979-01-01

    A series of N-methyl substituted aromatic polyamides derived from the secondary aromatic diamines, 4,4'-bis(methylamino)diphenylmethane, 3,3'-bis(methylamino) diphenylmethane, 4,4'-bis(methylamino)benzophenone or 3,3'-bis(methylamino)benzophenone and isophthaloyl dichloride, terphthaloyl dichloride or 3,3'diphenylmethane dicarboxylic acid dichloride was prepared by high temperature solution polymerization in s-tetrachloroethane. Compared to analogous unsubstituted and partially N-methylated aromatic polyamides, the full N-methylated polyamides exhibited significantly lower glass transition temperatures, reduced crystallinity, improved thermal stability and good solubility in chlorinated solvents.

  11. Six-Membered Aromatic Polyazides: Synthesis and Application.

    PubMed

    Chapyshev, Sergei V

    2015-10-21

    Aromatic polyazides are widely used as starting materials in organic synthesis and photochemical studies, as well as photoresists in microelectronics and as cross-linking agents in polymer chemistry. Some aromatic polyazides possess high antitumor activity, while many others are of considerable interest as high-energy materials and precursors of high-spin nitrenes and C₃N₄ carbon nitride nanomaterials. The use of aromatic polyazides in click-reactions may be a new promising direction in the design of various supramolecular systems possessing interesting chemical, physical and biological properties. This review is devoted to the synthesis, properties and applications of six-membered aromatic compounds containing three and more azido groups in the ring.

  12. Three-dimensional aromatic networks.

    PubMed

    Toyota, Shinji; Iwanaga, Tetsuo

    2014-01-01

    Three-dimensional (3D) networks consisting of aromatic units and linkers are reviewed from various aspects. To understand principles for the construction of such compounds, we generalize the roles of building units, the synthetic approaches, and the classification of networks. As fundamental compounds, cyclophanes with large aromatic units and aromatic macrocycles with linear acetylene linkers are highlighted in terms of transannular interactions between aromatic units, conformational preference, and resolution of chiral derivatives. Polycyclic cage compounds are constructed from building units by linkages via covalent bonds, metal-coordination bonds, or hydrogen bonds. Large cage networks often include a wide range of guest species in their cavity to afford novel inclusion compounds. Topological isomers consisting of two or more macrocycles are formed by cyclization of preorganized species. Some complicated topological networks are constructed by self-assembly of simple building units.

  13. Hydrophilic properties of aromatics.

    PubMed

    Bonadeo, I; Lodi, V; Ghidini, D

    1980-10-01

    Synopsis The study of the behaviour of perfume ingredients in emulsions involves several technological problems. Recently, the scientific and practical validity of the parameter known as 'hydrophilic value' K(d) (according to Bonadeo) was recognised; it relates to the behaviour of fatty materials in emulsions. The purpose of this research was to verify the reliability of the above parameter as applied to perfume ingredients. From the experimental results it is possible to establish a mathematical relationship between K(d) and the 'required emulsification value' (HLB(r)) of the aromatics used in perfuming cosmetics and toiletries. From the K(d) value it is possible to calculate the critical limit of the water phase (CLWP) concerning the single ingredients of a perfume compound. These parameters are particularly important in predicting the optimal behaviour of perfumes in the chemical-physical balance of emulsions, with which are connected the principal parameters of the chemical and olfactive stability. Thus, in practice, it has been demonstrated that the perfumed substances behave as, and can be considered as, other fatty bodies forming the fatty phase of emulsions.

  14. Synthesis, spectral, thermal and biological studies on N-(2,4-dinitro-phenyl)-2-mercaptoacetohydrazide and its metal complexes

    NASA Astrophysics Data System (ADS)

    El-Asmy, A. A.; Rakha, T. H.; Abdel-Rhman, M. H.; Hassanien, M. M.; Al-Mola, A. S.

    2015-02-01

    Complexes of VO2+, Cr3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+ and Hg2+ ions with N-(2,4-dinitrophenyl)-2-mercaptoacetohydrazide (H2L) have been prepared and characterized on the basis of elemental analysis, molar conductance, thermal (TGA, DTGA), spectral (IR, NMR, UV-Visible, MS) and magnetic measurements. The IR spectra show that H2L behaves in a mononegative and/or binegative bidentate manner. The sulfate bridged the two complex molecules in [Cu(HL)(H2O)2(½SO4)]ṡ3H2O. The acetate functions as a monodentate in [Ni(HL)(OAc)(H2O)3] and [Cr(HL)(OAc)2(H2O)(EtOH)]. Different stereochemistries are proposed: octahedral for Cr(III), Ni(II), Hg(II) and [Cu(HL)(H2O)2(SO4)0.5]ṡ3H2O, square-based pyramid for [VO(HL)2]ṡEtOH, square-planar for [Co(L)(EtOH)(H2O)]ṡH2O, [Cu(L)(H2O)2] and tetrahedral for [Zn(L)(EtOH)(H2O)], [Cd(L)(EtOH)(H2O)] and [Cu2(HL)(H2O)6]Cl3ṡH2O according to the data of electronic spectra and magnetic measurements. The TGA data support the formula and indicate the outer and inner solvents as well as the final residue. The thermodynamic parameters are calculated using the Coats-Redfern and Horowitz-Metzger methods. H2L and [Zn(L)(EtOH)(H2O)] showed the highest cytotoxic activity while H2L has a higher antioxidant activity than ascorbic acid. The ionization constant of the ligand and the stability constant of the Cu(II)sbnd H2L in absence and presence of hexamine buffer were calculated.

  15. Polybenzoxazole via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

    Hergenrother, Paul M. (Inventor); Connell, John W. (Inventor); Smith, Joseph G., Jr. (Inventor)

    1993-01-01

    Polybenzoxazoles (PBO) are heterocyclic macromolecules which were first synthesized in a two-step process by the initial formation of aromatic diacid chlorides with bis(o-aminophenol)s through solution condensation of aromatic diacid chlorides with bis(o-aminophenol)s followed by thermal cyclodehydration. Since then several methods were utilized in their synthesis. The most common synthetic method for PBO involves a polycondensation of bis(o-aminophenol)s with aromatic diacid diphenyl esters. Another preparative route involves the solution polycondensation of the hydrochloride salts of bis(o-amino phenol)s with aromatic diacids in polyphosphoric acid. Another synthetic method involves the initial formation of poly(o-hydroxy amide)s from silylated bis(o-aminophenol)s with aromatic diacid chlorides followed by thermal cyclodehydration to PBO. A recent preparative route involves the reaction of aromatic bisphenols with bis(fluorophenyl) benzoxazoles by the displacement reaction to form PBO. The novelty of the present invention is that high molecular weight PBO of new chemical structures are prepared that exhibit a favorable combination of physical and mechanical properties.

  16. Gallium Zeolites for Light Paraffin Aromatization

    SciTech Connect

    Price, G.L.; Dooley, K.M.

    1999-02-10

    The primary original goal of this project was to investigate the active state of gallium-containing MFI catalysts for light paraffin aromatization, in particular the state of gallium in the active material. Our original hypothesis was that the most active and selective materials were those which contained gallium zeolitic cations, and that previously reported conditions for the activation of gallium-containing catalysts served to create these active centers. We believed that in high silica materials such as MFI, ion-exchange is most effectively accomplished with metals in their 1+ oxidation state, both because of the sparsity of the anionic ion-exchange sites associated with the zeolite, and because the large hydration shells associated with aqueous 3+ cations hinder transport. Metals such as Ga which commonly exist in higher oxidation states need to be reduced to promote ion-exchange and this is the reason that reduction of gallium-containing catalysts for light paraffin aromatization often yields a dramatic enhancement in catalytic activity. We have effectively combined reduction with ion-exchange and we term this combined process ''reductive solid-state ion-exchange''. Our hypothesis has largely been proven true, and a number of the papers we have published directly address this hypothesis.

  17. Oxidation of aromatic contaminants coupled to microbial iron reduction

    USGS Publications Warehouse

    Lovley, D.R.; Baedecker, M.J.; Lonergan, D.J.; Cozzarelli, I.M.; Phillips, E.J.P.; Siegel, D.I.

    1989-01-01

    THE contamination of sub-surface water supplies with aromatic compounds is a significant environmental concern1,2. As these contaminated sub-surface environments are generally anaerobic, the microbial oxidation of aromatic compounds coupled to nitrate reduction, sulphate reduction and methane production has been studied intensively1-7. In addition, geochemical evidence suggests that Fe(III) can be an important electron acceptor for the oxidation of aromatic compounds in anaerobic groundwater. Until now, only abiological mechanisms for the oxidation of aromatic compounds with Fe(III) have been reported8-12. Here we show that in aquatic sediments, microbial activity is necessary for the oxidation of model aromatic compounds coupled to Fe(III) reduction. Furthermore, a pure culture of the Fe(III)-reducing bacterium GS-15 can obtain energy for growth by oxidizing benzoate, toluene, phenol or p-cresol with Fe(III) as the sole electron acceptor. These results extend the known physiological capabilities of Fe(III)-reducing organisms and provide the first example of an organism of any type which can oxidize an aromatic hydrocarbon anaerobically. ?? 1989 Nature Publishing Group.

  18. Polycyclic Aromatic Hydrocarbons

    NASA Technical Reports Server (NTRS)

    Salama, Farid

    2010-01-01

    Carbonaceous materials play an important role in space. Polycyclic Aromatic Hydrocarbons (PAHs) are a ubiquitous component of the carbonaceous materials. PAHs are the best-known candidates to account for the IR emission bands. They are also thought to be among the carriers of the diffuse interstellar absorption bands (DIBs). PAH ionization states reflect the ionization balance of the medium while PAH size, composition, and structure reflect the energetic and chemical history of the medium. A major challenge is to reproduce in the laboratory the physical conditions that exist in the emission and absorption interstellar zones. The harsh physical conditions of the ISM -low temperature, collisionless, strong UV radiation fields- are simulated in the laboratory by associating a molecular beam with an ionizing discharge to generate a cold plasma expansion. PAH ions and radicals are formed from the neutral precursors in an isolated environment at low temperature and probed with high-sensitivity cavity ringdown spectroscopy in the NUV-NIR range. Carbon nanoparticles are also formed during the short residence time of the precursors in the plasma and are characterized with time-offlight mass spectrometry. These experiments provide unique information on the spectra of large carbonaceous molecules and ions in the gas phase that can now be directly compared to interstellar and circumstellar observations (IR emission bands, DIBs, extinction curve). These findings also hold great potential for understanding the formation process of interstellar carbonaceous grains. We will review recent progress in the experimental and theoretical studies of PAHs, compare the laboratory data with astronomical observations and discuss the global implications.

  19. New and extended parameterization of the thermodynamic model AIOMFAC: calculation of activity coefficients for organic-inorganic mixtures containing carboxyl, hydroxyl, carbonyl, ether, ester, alkenyl, alkyl, and aromatic functional groups

    NASA Astrophysics Data System (ADS)

    Zuend, A.; Marcolli, C.; Booth, A. M.; Lienhard, D. M.; Soonsin, V.; Krieger, U. K.; Topping, D. O.; McFiggans, G.; Peter, T.; Seinfeld, J. H.

    2011-05-01

    We present a new and considerably extended parameterization of the thermodynamic activity coefficient model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) at room temperature. AIOMFAC combines a Pitzer-like electrolyte solution model with a UNIFAC-based group-contribution approach and explicitly accounts for interactions between organic functional groups and inorganic ions. Such interactions constitute the salt-effect, may cause liquid-liquid phase separation, and affect the gas-particle partitioning of aerosols. The previous AIOMFAC version was parameterized for alkyl and hydroxyl functional groups of alcohols and polyols. With the goal to describe a wide variety of organic compounds found in atmospheric aerosols, we extend here the parameterization of AIOMFAC to include the functional groups carboxyl, hydroxyl, ketone, aldehyde, ether, ester, alkenyl, alkyl, aromatic carbon-alcohol, and aromatic hydrocarbon. Thermodynamic equilibrium data of organic-inorganic systems from the literature are critically assessed and complemented with new measurements to establish a comprehensive database. The database is used to determine simultaneously the AIOMFAC parameters describing interactions of organic functional groups with the ions H+, Li+, Na+, K+, NH4+, Mg2+, Ca2+, Cl-, Br-, NO3-, HSO4-, and SO42-. Detailed descriptions of different types of thermodynamic data, such as vapor-liquid, solid-liquid, and liquid-liquid equilibria, and their use for the model parameterization are provided. Issues regarding deficiencies of the database, types and uncertainties of experimental data, and limitations of the model, are discussed. The challenging parameter optimization problem is solved with a novel combination of powerful global minimization algorithms. A number of exemplary calculations for systems containing atmospherically relevant aerosol components are shown. Amongst others, we discuss aqueous mixtures of ammonium sulfate with

  20. New and extended parameterization of the thermodynamic model AIOMFAC: calculation of activity coefficients for organic-inorganic mixtures containing carboxyl, hydroxyl, carbonyl, ether, ester, alkenyl, alkyl, and aromatic functional groups

    NASA Astrophysics Data System (ADS)

    Zuend, A.; Marcolli, C.; Booth, A. M.; Lienhard, D. M.; Soonsin, V.; Krieger, U. K.; Topping, D. O.; McFiggans, G.; Peter, T.; Seinfeld, J. H.

    2011-09-01

    We present a new and considerably extended parameterization of the thermodynamic activity coefficient model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) at room temperature. AIOMFAC combines a Pitzer-like electrolyte solution model with a UNIFAC-based group-contribution approach and explicitly accounts for interactions between organic functional groups and inorganic ions. Such interactions constitute the salt-effect, may cause liquid-liquid phase separation, and affect the gas-particle partitioning of aerosols. The previous AIOMFAC version was parameterized for alkyl and hydroxyl functional groups of alcohols and polyols. With the goal to describe a wide variety of organic compounds found in atmospheric aerosols, we extend here the parameterization of AIOMFAC to include the functional groups carboxyl, hydroxyl, ketone, aldehyde, ether, ester, alkenyl, alkyl, aromatic carbon-alcohol, and aromatic hydrocarbon. Thermodynamic equilibrium data of organic-inorganic systems from the literature are critically assessed and complemented with new measurements to establish a comprehensive database. The database is used to determine simultaneously the AIOMFAC parameters describing interactions of organic functional groups with the ions H+, Li+, Na+, K+, NH4+, Mg2+, Ca2+, Cl-, Br-, NO3-, HSO4-, and SO42-. Detailed descriptions of different types of thermodynamic data, such as vapor-liquid, solid-liquid, and liquid-liquid equilibria, and their use for the model parameterization are provided. Issues regarding deficiencies of the database, types and uncertainties of experimental data, and limitations of the model, are discussed. The challenging parameter optimization problem is solved with a novel combination of powerful global minimization algorithms. A number of exemplary calculations for systems containing atmospherically relevant aerosol components are shown. Amongst others, we discuss aqueous mixtures of ammonium sulfate with

  1. Chemical Composition and Biological Activity of Essential Oils from Wild Growing Aromatic Plant Species of Skimmia laureola and Juniperus macropoda from Western Himalaya.

    PubMed

    Stappen, Iris; Tabanca, Nurhayat; Ali, Abbas; Wedge, David E; Wanner, Jürgen; Kaul, Vijay K; Lal, Brij; Jaitak, Vikas; Gochev, Velizar K; Schmidt, Erich; Jirovetz, Leopold

    2015-06-01

    The Himalayan region is very rich in a great variety of medicinal plants. In this investigation the essential oils of two selected species are described for their antimicrobial and larvicidal as well as biting deterrent activities. Additionally, the odors are characterized. Analyzed by simultaneous GC-MS and GC-FID, the essential oils' chemical compositions are given. The main components of Skimmia laureola oil were linalool and linalyl acetate whereas sabinene was found as the main compound for Juniperus macropoda essential oil. Antibacterial testing by agar dilution assay revealed highest activity of S. laureola oil against all tested bacteria, followed by J. macropoda oil. Antifungal activity was evaluated against the strawberry anthracnose causing plant pathogens Colletotrichum acutatum, C. fragariae and C. gloeosporioides. Juniperus macropoda essential oil indicated higher antifungal activity against all three pathogens than S. laureola oil. Both essential oils showed biting deterrent activity above solvent control but low larvicidal activity.

  2. Chemical Composition and Biological Activity of Essential Oils from Wild Growing Aromatic Plant Species of Skimmia laureola and Juniperus macropoda from Western Himalaya.

    PubMed

    Stappen, Iris; Tabanca, Nurhayat; Ali, Abbas; Wedge, David E; Wanner, Jürgen; Kaul, Vijay K; Lal, Brij; Jaitak, Vikas; Gochev, Velizar K; Schmidt, Erich; Jirovetz, Leopold

    2015-06-01

    The Himalayan region is very rich in a great variety of medicinal plants. In this investigation the essential oils of two selected species are described for their antimicrobial and larvicidal as well as biting deterrent activities. Additionally, the odors are characterized. Analyzed by simultaneous GC-MS and GC-FID, the essential oils' chemical compositions are given. The main components of Skimmia laureola oil were linalool and linalyl acetate whereas sabinene was found as the main compound for Juniperus macropoda essential oil. Antibacterial testing by agar dilution assay revealed highest activity of S. laureola oil against all tested bacteria, followed by J. macropoda oil. Antifungal activity was evaluated against the strawberry anthracnose causing plant pathogens Colletotrichum acutatum, C. fragariae and C. gloeosporioides. Juniperus macropoda essential oil indicated higher antifungal activity against all three pathogens than S. laureola oil. Both essential oils showed biting deterrent activity above solvent control but low larvicidal activity. PMID:26197554

  3. Aromatic fluorine compounds. VII. Replacement of aromatic -Cl and -NO2 groups by -F

    USGS Publications Warehouse

    Finger, G.C.; Kruse, C.W.

    1956-01-01

    Replacement of -Cl by -F in aryl chlorides with potassium fluoride has been extended from 2,4-dinitrochlorobenzene to less activated halides by the use of non-aqueous solvents, especially dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). Also replacement of -NO2 by -F in substituted nitrobenzenes was studied in DMF. As a direct result of this study, many aromatic fluorine compounds can now be obtained by a relatively simple synthetic route.

  4. Bacterial degradation of monocyclic aromatic amines

    PubMed Central

    Arora, Pankaj K.

    2015-01-01

    Aromatic amines are an important group of industrial chemicals, which are widely used for manufacturing of dyes, pesticides, drugs, pigments, and other industrial products. These compounds have been considered highly toxic to human beings due to their carcinogenic nature. Three groups of aromatic amines have been recognized: monocyclic, polycyclic, and heterocyclic aromatic amines. Bacterial degradation of several monocyclic aromatic amines has been studied in a variety of bacteria, which utilizes monocyclic aromatic amines as their sole source of carbon and energy. Several degradation pathways have been proposed and the related enzymes and genes have also been characterized. Many reviews have been reviewed toxicity of monocyclic aromatic amines; however, there is lack of review on biodegradation of monocyclic aromatic amines. The aim of this review is to summarize bacterial degradation of monocyclic aromatic amines. This review will increase our current understanding of biochemical and molecular basis of bacterial degradation of monocyclic aromatic amines. PMID:26347719

  5. Potential Metabolic Activation of a Representative C2-Alkylated Polycyclic Aromatic Hydrocarbon 6-Ethylchrysene Associated with the Deepwater Horizon Oil Spill in Human Hepatoma (HepG2) Cells

    PubMed Central

    2016-01-01

    Exposure to polycyclic aromatic hydrocarbons (PAHs) is the major human health hazard associated with the Deepwater Horizon oil spill. C2-Chrysenes are representative PAHs present in crude oil and could contaminate the food chain. We describe the metabolism of a C2-chrysene regioisomer, 6-ethylchrysene (6-EC), in human HepG2 cells. The structures of the metabolites were identified by HPLC-UV-fluorescence detection and LC-MS/MS. 6-EC-tetraol isomers were identified as signature metabolites of the diol-epoxide pathway. O-Monomethyl-O-monosulfonated-6-EC-catechol, its monohydroxy products, and N-acetyl-l-cysteine(NAC)-6-EC-ortho-quinone were discovered as signature metabolites of the ortho-quinone pathway. Potential dual metabolic activation of 6-EC involving the formation of bis-electrophiles, i.e., a mono-diol-epoxide and a mono-ortho-quinone within the same structure, bis-diol-epoxides, and bis-ortho-quinones was observed as well. The identification of 6-EC-tetraol, O-monomethyl-O-monosulfonated-6-EC-catechol, its monohydroxy products, and NAC-6-EC-ortho-quinone supports potential metabolic activation of 6-EC by P450 and AKR enzymes followed by metabolic detoxification of the ortho-quinone through interception of its redox cycling capability by catechol-O-methyltransferase and sulfotransferase enzymes. The tetraols and catechol conjugates could be used as biomarkers of human exposure to 6-EC resulting from oil spills. PMID:27054409

  6. Potential Metabolic Activation of a Representative C2-Alkylated Polycyclic Aromatic Hydrocarbon 6-Ethylchrysene Associated with the Deepwater Horizon Oil Spill in Human Hepatoma (HepG2) Cells.

    PubMed

    Huang, Meng; Mesaros, Clementina; Zhang, Suhong; Blair, Ian A; Penning, Trevor M

    2016-06-20

    Exposure to polycyclic aromatic hydrocarbons (PAHs) is the major human health hazard associated with the Deepwater Horizon oil spill. C2-Chrysenes are representative PAHs present in crude oil and could contaminate the food chain. We describe the metabolism of a C2-chrysene regioisomer, 6-ethylchrysene (6-EC), in human HepG2 cells. The structures of the metabolites were identified by HPLC-UV-fluorescence detection and LC-MS/MS. 6-EC-tetraol isomers were identified as signature metabolites of the diol-epoxide pathway. O-Monomethyl-O-monosulfonated-6-EC-catechol, its monohydroxy products, and N-acetyl-l-cysteine(NAC)-6-EC-ortho-quinone were discovered as signature metabolites of the ortho-quinone pathway. Potential dual metabolic activation of 6-EC involving the formation of bis-electrophiles, i.e., a mono-diol-epoxide and a mono-ortho-quinone within the same structure, bis-diol-epoxides, and bis-ortho-quinones was observed as well. The identification of 6-EC-tetraol, O-monomethyl-O-monosulfonated-6-EC-catechol, its monohydroxy products, and NAC-6-EC-ortho-quinone supports potential metabolic activation of 6-EC by P450 and AKR enzymes followed by metabolic detoxification of the ortho-quinone through interception of its redox cycling capability by catechol-O-methyltransferase and sulfotransferase enzymes. The tetraols and catechol conjugates could be used as biomarkers of human exposure to 6-EC resulting from oil spills.

  7. Potential Metabolic Activation of a Representative C2-Alkylated Polycyclic Aromatic Hydrocarbon 6-Ethylchrysene Associated with the Deepwater Horizon Oil Spill in Human Hepatoma (HepG2) Cells.

    PubMed

    Huang, Meng; Mesaros, Clementina; Zhang, Suhong; Blair, Ian A; Penning, Trevor M

    2016-06-20

    Exposure to polycyclic aromatic hydrocarbons (PAHs) is the major human health hazard associated with the Deepwater Horizon oil spill. C2-Chrysenes are representative PAHs present in crude oil and could contaminate the food chain. We describe the metabolism of a C2-chrysene regioisomer, 6-ethylchrysene (6-EC), in human HepG2 cells. The structures of the metabolites were identified by HPLC-UV-fluorescence detection and LC-MS/MS. 6-EC-tetraol isomers were identified as signature metabolites of the diol-epoxide pathway. O-Monomethyl-O-monosulfonated-6-EC-catechol, its monohydroxy products, and N-acetyl-l-cysteine(NAC)-6-EC-ortho-quinone were discovered as signature metabolites of the ortho-quinone pathway. Potential dual metabolic activation of 6-EC involving the formation of bis-electrophiles, i.e., a mono-diol-epoxide and a mono-ortho-quinone within the same structure, bis-diol-epoxides, and bis-ortho-quinones was observed as well. The identification of 6-EC-tetraol, O-monomethyl-O-monosulfonated-6-EC-catechol, its monohydroxy products, and NAC-6-EC-ortho-quinone supports potential metabolic activation of 6-EC by P450 and AKR enzymes followed by metabolic detoxification of the ortho-quinone through interception of its redox cycling capability by catechol-O-methyltransferase and sulfotransferase enzymes. The tetraols and catechol conjugates could be used as biomarkers of human exposure to 6-EC resulting from oil spills. PMID:27054409

  8. Inhibition of coal fly ash polycyclic aromatic hydrocarbons and metals induced mixed-function oxidase activity in rat lung and liver by vitamin A and citrate

    SciTech Connect

    Chauhan, S.S.; Srivastava, P.K.; Srivastava, V.K.; Kumar, V.; Misra, U.K.

    1986-01-01

    Administration of benzene-soluble fraction (FAE) and benzene-insoluble fraction (FAR) of fly ash for 3 consecutive days to rats significantly raised cytochrome P-450 levels, aryl hydrocarbon hydroxylase (AHH) activity, and glutathione S-transferase activity in liver. This treatment also significantly increased pulmonary AHH and glutathione S-transferase activity. Intratracheal administration of FAR (5 mg/100 g body weight) alone for 6 consecutive days also significantly increased hepatic cytochrome P-450 levels and the activity of glutathione S-transferase. Intragastric administration of retinyl palmitate (5000 IU/100 g body weight), along with intratracheal FAE and FAR administration, significantly reduced P-450 levels, activity of glutathione S-transferase in liver, and activity of AHH and glutathione S-transferase in lung of rats. Intraperitoneal administration of citrate (40 mg/100 g body weight) along with FAR significantly reduced FAR-induced increase in hepatic cytochrome P-450 levels and glutathione S-transferase activity. The activity of AHH was not affected by these treatments.

  9. Effects of low molecular-weight organic acids and dehydrogenase activity in rhizosphere sediments of mangrove plants on phytoremediation of polycyclic aromatic hydrocarbons.

    PubMed

    Wang, Yuanyuan; Fang, Ling; Lin, Li; Luan, Tiangang; Tam, Nora F Y

    2014-03-01

    This work evaluated the roles of the low-molecular-weight organic acids (LMWOAs) from root exudates and the dehydrogenase activity in the rhizosphere sediments of three mangrove plant species on the removal of mixed PAHs. The results showed that the concentrations of LMWOAs and dehydrogenase activity changed species-specifically with the levels of PAH contamination. In all plant species, the concentration of citric acid was the highest, followed by succinic acid. For these acids, succinic acid was positively related to the removal of all the PAHs except Chr. Positive correlations were also found between the removal percentages of 4-and 5-ring PAHs and all LMWOAs, except citric acid. LMWOAs enhanced dehydrogenase activity, which positively related to PAH removal percentages. These findings suggested that LMWOAs and dehydrogenase activity promoted the removal of PAHs. Among three mangrove plants, Bruguiera gymnorrhiza, the plant with the highest root biomass, dehydrogenase activity and concentrations of LMWOAs, was most efficient in removing PAHs. PMID:24287262

  10. Effects of low molecular-weight organic acids and dehydrogenase activity in rhizosphere sediments of mangrove plants on phytoremediation of polycyclic aromatic hydrocarbons.

    PubMed

    Wang, Yuanyuan; Fang, Ling; Lin, Li; Luan, Tiangang; Tam, Nora F Y

    2014-03-01

    This work evaluated the roles of the low-molecular-weight organic acids (LMWOAs) from root exudates and the dehydrogenase activity in the rhizosphere sediments of three mangrove plant species on the removal of mixed PAHs. The results showed that the concentrations of LMWOAs and dehydrogenase activity changed species-specifically with the levels of PAH contamination. In all plant species, the concentration of citric acid was the highest, followed by succinic acid. For these acids, succinic acid was positively related to the removal of all the PAHs except Chr. Positive correlations were also found between the removal percentages of 4-and 5-ring PAHs and all LMWOAs, except citric acid. LMWOAs enhanced dehydrogenase activity, which positively related to PAH removal percentages. These findings suggested that LMWOAs and dehydrogenase activity promoted the removal of PAHs. Among three mangrove plants, Bruguiera gymnorrhiza, the plant with the highest root biomass, dehydrogenase activity and concentrations of LMWOAs, was most efficient in removing PAHs.

  11. N,N-Diethyl-anilinium 5-(5-chloro-2,4-dinitro-phen-yl)-2,6-dioxo-1,2,3,6-tetra-hydro-pyrimidin-4-olate.

    PubMed

    Babykala, R; Kalaivani, D

    2013-03-01

    In the anion of the title salt, C10H16N(+)·C10H4ClN4O7(-) [trivial name = N,N-diethyl-anilinium 5-(3-chloro-4,6,-dinitro-phen-yl)barbiturate], the dihedral angle between the benzene and pyrimidine rings is 45.49 (6)°. The mean plane of the nitro group, which is ortho-substituted with respect to the pyrimidine ring, is twisted by 41.57 (13)° from the benzene ring, while the mean plane of the nitro group, which is para-substituted, is twisted by 14.41 (12)° from this ring. In the crystal, N-H⋯O hydrogen bonds link cations and anions into chains along [1-10]. Within the chains, inversion-related anionic barbiturate anions form R2(2)(8) ring motifs. PMID:23476581

  12. 2-(4-Amino­benzene­sulfonamido)-4,6-dimethyl­pyrimidin-1-ium 2-carb­oxy-4,6-dinitro­phenolate

    PubMed Central

    Smith, Graham; Wermuth, Urs D.

    2013-01-01

    In the structure of the phenolate salt of the sulfa drug sulfamethazine with 3,5-dinitro­salicylic acid, C12H15N4O2S+·C7H3N2O7 −, the dihedral angle between the pyrimidine and benzene rings of the cation is 59.70 (17)°. In the crystal, cation–anion hydrogen-bonding inter­actions involving pyrim­idine–carb­oxy N+—H⋯O and amine–carb­oxy N—H⋯O pairs give a cyclic R 2 2(8) motif while secondary N—H⋯O hydrogen bonds between the aniline group and both sulfone and nitro O-atom acceptors give a two-dimensional structure extending in (001). PMID:23634030

  13. Aromatization and etherification process integration

    SciTech Connect

    Harandi, M.N.; Owen, H.

    1989-08-08

    This patent describes a continuous process for the production of aromatics-rich high octane gasoline and ether-rich high octane gasoline. It comprises the steps of: contacting a C/sub 4/+ hydrocarbon feedstream containing iso-olefins and excess methanol based on the iso-olefins with an acid etherification catalyst under etherification conditions in an etherification zone whereby an effluent stream is produced comprising methyl tertiary alkyl ethers, unreacted methanol and hydrocarbons; distilling the effluent stream whereby a distillate bottom stream is produced comprising high octane ether-rich C/sub 5/+ gasoline and a distillate overhead stream comprising unreacted methanol and C/sub 5/- hydrocarbons; passing the distillate overhead stream and an aromatization hydrocarbon feedstream comprising an ethene rich gas feedstream and C/sub 3/ hydrocarbons to an olefins and paraffins fixed, fluid or moving bed aromatization zone under aromatization conditions in contact with medium pore size shape selective metallosilicate catalyst having the structure of ZSM-5 whereby a high octane aromatics-rich C/sub 5/+ gasoline is procluded and hydrogen-rich fuel gas.

  14. Iridium-catalyzed intermolecular dehydrogenative silylation of polycyclic aromatic compounds without directing groups.

    PubMed

    Murai, Masahito; Takami, Keishi; Takai, Kazuhiko

    2015-03-16

    This study describes the iridium-catalyzed intermolecular dehydrogenative silylation of C(sp(2))-H bonds of polycyclic aromatic compounds without directing groups. The reaction produced various arylsilanes through both Si-H and C-H bond activation, with hydrogen as the sole byproduct. Reactivity was affected by the electronic nature of the aromatic compounds, and silylation of electron-deficient and polycyclic aromatic compounds proceeded efficiently. Site-selectivity was controlled predominantly by steric factors. Therefore, the current functionalization proceeded with opposite chemo- and site-selectivity compared to that observed for general electrophilic functionalization of aromatic compounds.

  15. Detection of chlorinated aromatic compounds

    DOEpatents

    Ekechukwu, Amy A.

    1996-01-01

    A method for making a composition for measuring the concentration of chloated aromatic compounds in aqueous fluids, and an optical probe for use with the method. The composition comprises a hydrophobic polymer matrix, preferably polyamide, with a fluorescent indicator uniformly dispersed therein. The indicator fluoresces in the presence of the chlorinated aromatic compounds with an intensity dependent on the concentration of these compounds in the fluid of interest, such as 8-amino-2-naphthalene sulfonate. The probe includes a hollow cylindrical housing that contains the composition in its distal end. The probe admits an aqueous fluid to the probe interior for exposure to the composition. An optical fiber transmits excitation light from a remote source to the composition while the indicator reacts with chlorinated aromatic compounds present in the fluid. The resulting fluorescence light signal is reflected to a second optical fiber that transmits the light to a spectrophotometer for analysis.

  16. Detection of chlorinated aromatic compounds

    DOEpatents

    Ekechukwu, A.A.

    1996-02-06

    A method for making a composition for measuring the concentration of chlorinated aromatic compounds in aqueous fluids, and an optical probe for use with the method are disclosed. The composition comprises a hydrophobic polymer matrix, preferably polyamide, with a fluorescent indicator uniformly dispersed therein. The indicator fluoresces in the presence of the chlorinated aromatic compounds with an intensity dependent on the concentration of these compounds in the fluid of interest, such as 8-amino-2-naphthalene sulfonate. The probe includes a hollow cylindrical housing that contains the composition in its distal end. The probe admits an aqueous fluid to the probe interior for exposure to the composition. An optical fiber transmits excitation light from a remote source to the composition while the indicator reacts with chlorinated aromatic compounds present in the fluid. The resulting fluorescence light signal is reflected to a second optical fiber that transmits the light to a spectrophotometer for analysis. 5 figs.

  17. Antibacterial activity of water extracts and essential oils of various aromatic plants against Paenibacillus larvae, the causative agent of American Foulbrood.

    PubMed

    González, M J; Marioli, J M

    2010-07-01

    Vegetal water extracts, namely the water remaining after hydro-distillation and decoctions, and essential oils of 10 plant species were tested as inhibitors for the growth of Paenibacillus larvae, the causative agent of American Foulbrood. Achyrocline satureioides, Chenopodium ambrosioide, Eucalyptus cinerea, Gnaphalium gaudichaudianum, Lippia turbinata, Marrubium vulgare,Minthostachys verticillata, Origanum vulgare, Tagetes minuta and Thymus vulgaris were included in the study. The water remaining after hydro-distillation showed the highest antibacterial activities, the growth of almost all the P. larvae strains tested was inhibited by these extracts. Regarding the plants tested, E. cinerea and M. verticillata were the plant species with the highest biological activity with 100% efficacy (all its extracts inhibited the growth of all P. larvae strains). Essential oils were less active for the inhibition of P. larvae growth.

  18. Volatile profiles of aromatic and non-aromatic rice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rice is enjoyed by many people as a staple food because of its flavor and texture. Some scented varieties command a premium in the marketplace because of their distinctive aroma and flavor. The compound most commonly associated with the popcorn or nutty scent of aromatic rice is 2-acetyl-1-pyrroline...

  19. Biosynthesis of the Aromatic Amino Acids.

    PubMed

    Pittard, James; Yang, Ji

    2008-09-01

    This chapter describes in detail the genes and proteins of Escherichia coli involved in the biosynthesis and transport of the three aromatic amino acids tyrosine, phenylalanine, and tryptophan. It provides a historical perspective on the elaboration of the various reactions of the common pathway converting erythrose-4-phosphate and phosphoenolpyruvate to chorismate and those of the three terminal pathways converting chorismate to phenylalanine, tyrosine, and tryptophan. The regulation of key reactions by feedback inhibition, attenuation, repression, and activation are also discussed. Two regulatory proteins, TrpR (108 amino acids) and TyrR (513 amino acids), play a major role in transcriptional regulation. The TrpR protein functions only as a dimer which, in the presence of tryptophan, represses the expression of trp operon plus four other genes (the TrpR regulon). The TyrR protein, which can function both as a dimer and as a hexamer, regulates the expression of nine genes constituting the TyrR regulon. TyrR can bind each of the three aromatic amino acids and ATP and under their influence can act as a repressor or activator of gene expression. The various domains of this protein involved in binding the aromatic amino acids and ATP, recognizing DNA binding sites, interacting with the alpha subunit of RNA polymerase, and changing from a monomer to a dimer or a hexamer are all described. There is also an analysis of the various strategies which allow TyrR in conjunction with particular amino acids to differentially affect the expression of individual genes of the TyrR regulon. PMID:26443741

  20. Coordinating activation strategy for C(sp3)–H/C(sp3)–H cross-coupling to access β-aromatic α-amino acids

    PubMed Central

    Li, Kaizhi; Wu, Qian; Lan, Jingbo; You, Jingsong

    2015-01-01

    The past decade has witnessed significant advances in C–H bond functionalizations with the discovery of new mechanisms. Non-precious transition-metal-catalysed radical oxidative coupling for C(sp3)–H bond transformations is an appealing strategy for C–C bond formations. The radical oxidative C(sp3)–H/C(sp3)–H cross-coupling reactions of α-C(sp3)–H bonds of amines with free radicals represent a conceptual and practical challenge. We herein develop the coordinating activation strategy to illustrate the nickel-catalysed radical oxidative cross-coupling between C(sp3)–H bonds and (hetero)arylmethyl free radicals. The protocol can tolerate a rich variety of α-amino acids and (hetero)arylmethanes as well as arylmethylenes and arylmethines, affording a large library of α-tertiary and α-quaternary β-aromatic α-amino acids. This process also features low-cost metal catalyst, readily handled and easily removable coordinating group, synthetic simplicity and gram-scale production, which would enable the potential for economical production at commercial scale in the future. PMID:26415985

  1. Phytochemical Profile and Evaluation of the Biological Activities of Essential Oils Derived from the Greek Aromatic Plant Species Ocimum basilicum, Mentha spicata, Pimpinella anisum and Fortunella margarita.

    PubMed

    Fitsiou, Eleni; Mitropoulou, Gregoria; Spyridopoulou, Katerina; Tiptiri-Kourpeti, Angeliki; Vamvakias, Manolis; Bardouki, Haido; Panayiotidis, Mihalis Ι; Galanis, Alex; Kourkoutas, Yiannis; Chlichlia, Katerina; Pappa, Aglaia

    2016-01-01

    Natural products, known for their medicinal properties since antiquity, are continuously being studied for their biological properties. In the present study, we analyzed the composition of the volatile preparations of essential oils of the Greek plants Ocimum basilicum (sweet basil), Mentha spicata (spearmint), Pimpinella anisum (anise) and Fortunella margarita (kumquat). GC/MS analyses revealed that the major components in the essential oil fractions, were carvone (85.4%) in spearmint, methyl chavicol (74.9%) in sweet basil, trans-anethole (88.1%) in anise, and limonene (93.8%) in kumquat. We further explored their biological potential by studying their antimicrobial, antioxidant and antiproliferative activities. Only the essential oils from spearmint and sweet basil demonstrated cytotoxicity against common foodborne bacteria, while all preparations were active against the fungi Saccharomyces cerevisiae and Aspergillus niger. Antioxidant evaluation by DPPH and ABTS radical scavenging activity assays revealed a variable degree of antioxidant potency. Finally, their antiproliferative potential was tested against a panel of human cancer cell lines and evaluated by using the sulforhodamine B (SRB) assay. All essential oil preparations exhibited a variable degree of antiproliferative activity, depending on the cancer model used, with the most potent one being sweet basil against an in vitro model of human colon carcinoma. PMID:27537869

  2. Catalytic C-H bond activation at nanoscale Lewis acidic aluminium fluorides: H/D exchange reactions at aromatic and aliphatic hydrocarbons.

    PubMed

    Prechtl, Martin H G; Teltewskoi, Michael; Dimitrov, Anton; Kemnitz, Erhard; Braun, Thomas

    2011-12-16

    Nanoscopic amorphous Lewis acidic aluminium fluorides, such as aluminium chlorofluoride (ACF) and high-surface aluminium fluoride (HS-AlF(3)), are capable of activating C-H bonds of aliphatic hydrocarbons. H/D exchange reactions are catalysed under mild conditions (40 °C).

  3. Phytochemical Profile and Evaluation of the Biological Activities of Essential Oils Derived from the Greek Aromatic Plant Species Ocimum basilicum, Mentha spicata, Pimpinella anisum and Fortunella margarita.

    PubMed

    Fitsiou, Eleni; Mitropoulou, Gregoria; Spyridopoulou, Katerina; Tiptiri-Kourpeti, Angeliki; Vamvakias, Manolis; Bardouki, Haido; Panayiotidis, Mihalis Ι; Galanis, Alex; Kourkoutas, Yiannis; Chlichlia, Katerina; Pappa, Aglaia

    2016-08-16

    Natural products, known for their medicinal properties since antiquity, are continuously being studied for their biological properties. In the present study, we analyzed the composition of the volatile preparations of essential oils of the Greek plants Ocimum basilicum (sweet basil), Mentha spicata (spearmint), Pimpinella anisum (anise) and Fortunella margarita (kumquat). GC/MS analyses revealed that the major components in the essential oil fractions, were carvone (85.4%) in spearmint, methyl chavicol (74.9%) in sweet basil, trans-anethole (88.1%) in anise, and limonene (93.8%) in kumquat. We further explored their biological potential by studying their antimicrobial, antioxidant and antiproliferative activities. Only the essential oils from spearmint and sweet basil demonstrated cytotoxicity against common foodborne bacteria, while all preparations were active against the fungi Saccharomyces cerevisiae and Aspergillus niger. Antioxidant evaluation by DPPH and ABTS radical scavenging activity assays revealed a variable degree of antioxidant potency. Finally, their antiproliferative potential was tested against a panel of human cancer cell lines and evaluated by using the sulforhodamine B (SRB) assay. All essential oil preparations exhibited a variable degree of antiproliferative activity, depending on the cancer model used, with the most potent one being sweet basil against an in vitro model of human colon carcinoma.

  4. A Comprehensive Review on the Phytochemical Constituents and Pharmacological Activities of Pogostemon cablin Benth.: An Aromatic Medicinal Plant of Industrial Importance.

    PubMed

    Swamy, Mallappa Kumara; Sinniah, Uma Rani

    2015-01-01

    Pogostemon cablin Benth. (patchouli) is an important herb which possesses many therapeutic properties and is widely used in the fragrance industries. In traditional medicinal practices, it is used to treat colds, headaches, fever, nausea, vomiting, diarrhea, abdominal pain, insect and snake bites. In aromatherapy, patchouli oil is used to relieve depression, stress, calm nerves, control appetite and to improve sexual interest. Till now more than 140 compounds, including terpenoids, phytosterols, flavonoids, organic acids, lignins, alkaloids, glycosides, alcohols, aldehydes have been isolated and identified from patchouli. The main phytochemical compounds are patchouli alcohol, α-patchoulene, β-patchoulene, α-bulnesene, seychellene, norpatchoulenol, pogostone, eugenol and pogostol. Modern studies have revealed several biological activities such as antioxidant, analgesic, anti-inflammatory, antiplatelet, antithrombotic, aphrodisiac, antidepressant, antimutagenic, antiemetic, fibrinolytic and cytotoxic activities. However, some of the traditional uses need to be verified and may require standardizing and authenticating the bioactivity of purified compounds through scientific methods. The aim of the present review is to provide comprehensive knowledge on the phytochemistry and pharmacological activities of essential oil and different plant extracts of patchouli based on the available scientific literature. This information will provide a potential guide in exploring the use of main active compounds of patchouli in various medical fields. PMID:25985355

  5. Chemical composition and biological activity of essential oils from wild growing aromatic plant species of Skimmia laureola and Juniperus macropoda from Western Himalaya

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Himalayan region is very rich in a great variety of medicinal plants. In this investigation the essential oils of two selected species are described for their antimicrobial and larvicidal as well as biting deterrent activities. Additionally, the odors are characterized. Analyzed by simultaneous ...

  6. Aromatic Gain in a Supramolecular Polymer.

    PubMed

    Saez Talens, Victorio; Englebienne, Pablo; Trinh, Thuat T; Noteborn, Willem E M; Voets, Ilja K; Kieltyka, Roxanne E

    2015-09-01

    The synergy of aromatic gain and hydrogen bonding in a supramolecular polymer is explored. Partially aromatic bis(squaramide) bolaamphiphiles were designed to self-assemble through a combination of hydrophobic, hydrogen-bonding, and aromatic effects into stiff, high-aspect-ratio fibers. UV and IR spectroscopy show electron delocalization and geometric changes within the squaramide ring indicative of strong hydrogen bonding and aromatic gain of the monomer units. The aromatic contribution to the interaction energy was further supported computationally by nucleus-independent chemical shift (NICS) and harmonic oscillator model of aromaticity (HOMA) indices, demonstrating greater aromatic character upon polymerization: at least 30% in a pentamer. The aromatic gain-hydrogen bonding synergy results in a significant increase in thermodynamic stability and a striking difference in aggregate morphology of the bis(squaramide) bolamphiphile compared to isosteres that cannot engage in this effect. PMID:26179942

  7. THE PHOTOTOXICITY OF POLYCYCLIC AROMATIC HYDROCARBONS

    EPA Science Inventory

    The U.S. Environmental Protection Agency (EPA) continues to be interested in developing methods for the detection of polycyclic aromatic hydrocarbons (PAHS) in the environment. Polycyclic aromatic hydrocarbons (PAHS) are common contaminants in our environment. Being major product...

  8. The Aromaticity of Pericyclic Reaction Transition States

    ERIC Educational Resources Information Center

    Rzepa, Henry S.

    2007-01-01

    An approach is presented that starts from two fundamental concepts in organic chemistry, chirality and aromaticity, and combines them into a simple rule for stating selection rules for pericyclic reactions in terms of achiral Huckel-aromatic and chiral Mobius-aromatic transition states. This is illustrated using an example that leads to apparent…

  9. Aryl hydrocarbon receptor mediated activities in road dust from a metropolitan area, Hanoi-Vietnam: contribution of polycyclic aromatic hydrocarbons (PAHs) and human risk assessment.

    PubMed

    Tuyen, Le Huu; Tue, Nguyen Minh; Suzuki, Go; Misaki, Kentaro; Viet, Pham Hung; Takahashi, Shin; Tanabe, Shinsuke

    2014-09-01

    Dioxin-Responsive Chemical-Activated LUciferase gene eXpression assay (DR-CALUX) was applied to assess the total toxic activity of the mixture of PAHs and related compounds as well as dioxin-related compounds in road dust from urban areas of Hanoi, Vietnam. Road dust from Hanoi contained significantly higher DR-CALUX activities (3 to 39, mean 20 ng CALUX-TEQ/g dw) than those from a rural site (2 to 13, mean 5 ng CALUX-TEQ/g dw). The total concentrations of 24 major PAHs (Σ24PAHs) in urban road dust (0.1 to 5.5, mean 2.5 μg/g dw) were also 6 times higher than those in rural road dust (0.08 to 1.5, mean 0.4 μg/g dw). Diagnostic ratios of PAHs indicated vehicular engine combustion as the major PAH emission source in both sites. PAHs accounted for 0.8 to 60% (mean 10%) and 2 to 76% (mean 20%) of the measured CALUX-TEQs in road dust for Hanoi the rural site, respectively. Benzo[b]-/benzo[k]fluoranthenes were the major TEQ contributors among PAHs, whereas DRCs contributed <0.1% to CALUX-TEQs for both rural and urban sites. These results suggest TEQ contribution of other aryl hydrocarbon receptor agonists in road dust. Significant PAH concentrations in urban dust indicated high mutagenic and carcinogenic potencies. Estimated results of incremental life time cancer risk (ILCR) indicated that Vietnamese populations, especially those in urban areas such as Hanoi, are potentially exposed to high cancer risk via both dust ingestion and dermal contact. This is the first study on the exposure risk of AhR agonists, including PAHs and DRCs, in urban road dust from a developing country using a combined bio-chemical analytical approach.

  10. Bioaccumulation of organochlorine contaminants and ethoxyresorufin-O-deethylase activity in southern California round stingrays (Urobatis halleri) exposed to planar aromatic compounds.

    PubMed

    Lyons, Kady; Lavado, Ramon; Schlenk, Daniel; Lowe, Christopher G

    2014-06-01

    While contaminant concentrations have been reported for elasmobranchs around the world, no studies have examined bioaccumulation patterns across male and female age classes. The round stingray (Urobatis halleri) is a local benthic species that forages near areas of high organochlorine contamination and represents a good elasmobranch model. Polychlorinated biphenyls (PCBs), DDT, and chlordanes were measured in juvenile and adult male and female stingrays from areas in southern California, USA (n = 208), and a nearby offshore island, Santa Catalina (n = 34). Both mainland juvenile male and female stingrays showed a significant dilution effect. After maturity, summed contaminant concentrations significantly increased with size for adult males (median 11.1 µg/g lipid wt) and females (5.2 µg/g lipid wt). However, the rate of bioaccumulation was substantially greater in male stingrays than in females, likely a result of the females' ability to offload contaminants to offspring during pregnancy. In addition, males and females showed significant differences in their contaminant profiles, suggesting differential habitat use. Male and female stingrays collected from Santa Catalina Island had significantly lower concentrations (0.51 µg/g and 0.66 µg/g lipid wt, respectively), approximately 5 times less than those of mainland animals. Potential toxicity effects mediated through activation of the aryl hydrocarbon receptor were explored through ethoxyresorufin-O-deethylase (EROD) activity assays. Mainland male stingrays exhibited significantly greater EROD activities than Catalina males (481 pmol/min/mg protein and 55 pmol/min/mg protein, respectively); however, activity levels in female stingrays from both locations were comparable (297 pmol/min/mg protein and 234 pmol/min/mg protein, respectively) and lower than those in mainland males. The results suggest that PCBs and/or other structurally related contaminants may be inducing a biological response

  11. A metal-bridged tricyclic aromatic system: synthesis of osmium polycyclic aromatic complexes.

    PubMed

    Zhu, Congqing; Zhu, Qin; Fan, Jinglan; Zhu, Jun; He, Xumin; Cao, Xiao-Yu; Xia, Haiping

    2014-06-10

    Aromaticity is one of the most important concepts in organic chemistry. A variety of metalla-aromatic compounds have been recently prepared and in most of those examples, the metal participates only in a monocyclic ring. In contrast, metal-bridged bicyclic aromatic molecules, in which a metal is shared between two aromatic rings, have been less developed. Herein, we report the first metal-bridged tricyclic aromatic system, in which the metal center is shared by three aromatic five-membered rings. These metalla-aromatics are formed by reaction between osmapentalyne and arene nucleophiles. Experimental results and theoretical calculations reveal that the three five-membered rings around the osmium center are aromatic. In addition, the broad absorption bands in the UV/Vis absorption spectra of these novel aromatic systems cover almost the entire visible region. This straightforward synthetic strategy may be extended to the synthesis of other metal-bridged polycyclic aromatics. PMID:24782397

  12. Phototransformation of polycyclic aromatic hydrocarbons into stable, mutagenic components

    SciTech Connect

    Okinaka, R.T.; Nickols, J.W.; Whaley, T.W.; Strniste, G.F.

    1983-01-01

    This report compares the mutagenicity of photochemical products produced by exposure of the polycyclic aromatic hydrocarbons benzo(a)pyrene and 9,10-dimethylanthracene or the aromatic amines 2-aminofluorene, 2-aminoanthracene and 2-aminonaphthalene to sunlight or to ultraviolet light (UVA). 2-Aminofluorene, giving the most active products, was further investigated with respect to the mechanism of photoactivation and the chemical identity of the photochemical products. Screening of HPLC resolved photochemical products demonstrated that the majority of the mutagenicity was localized to one peak - which co-chromatographed with 2-nitrofluorene.

  13. Catalytic decomposition of 4-phenoxyphenol to aromatics over Pd/Cs(x)H3.0-x PW12O40/activated carbon aerogel (X = 2.0-3.0).

    PubMed

    Park, Hai Woong; Hong, Ung Gi; Lee, Yoon Jae; Choi, Jung Ho; Song, In Kyu

    2013-12-01

    Cesium-exchanged heteropolyacid (Cs(x)H3.0-xPW12O40) was impregnated onto activated carbon aerogel (ACA) with a variation of cesium content (X = 2.0, 2.3, 2.5, 2.7, and 3.0) in order to provide acid sites to ACA. Palladium catalysts were then supported on Cs(x)H3.0-xPW12O40-impregnated activated carbon aerogel (Pd/Cs(x)H3.0-xPW12O40/ACA, X = 2.0-3.0) by an incipient wetness impregnation method for use in the decomposition of lignin model compound to aromatics. 4-Phenoxyphenol was used as a lignin model compound for representing 4-O-5 linkage of lignin. In the catalytic decomposition of 4-phenoxyphenol over Pd/Cs(X)H3.0-xPW12O40/ACA, cyclohexanol, benzene, and phenol were mainly produced. Conversion of 4-phenoxyphenol and total yield for main products (cyclohexanol, benzene, and phenol) were closely related to the acidity of Pd/Cs(x)H3.0-xPW12O40/ACA. Conversion of 4-phenoxyphenol and total yield for main products increased with increasing acidity of Pd/Cs(x)H3.0-xPW12O40/ACA. Among the catalysts tested, Pd/Cs2.5H0.5PW12O40/ACA catalyst with the largest acidity showed the highest conversion of 4-phenoxyphenol and total yield for main products. Therefore, it is concluded that acidity of catalysts would be an important factor determining the catalytic performance in the decomposition of 4-phenoxyphenol. PMID:24266173

  14. Pioneering Metal-Free Oxidative Coupling Strategy of Aromatic Compounds Using Hypervalent Iodine Reagents.

    PubMed

    Kita, Yasuyuki; Dohi, Toshifumi

    2015-10-01

    We started our hypervalent iodine research about 30 years ago in the mid-1980s. We soon successfully developed the single-electron-transfer oxidation ability of a hypervalent iodine reagent, specifically, phenyliodine(III) bis(trifluoroacetate) (PIFA), toward aromatic rings of phenyl ethers for forming aromatic cation radicals. This was one of the exciting and unexpected events in our research studies so far, and the discovery was reported in 1991. It also led to the next challenge, developing the metal-free oxidative couplings for C-H functionalizations and direct couplings between the C-H bonds of valuable aromatic compounds in organic synthesis. In order to realize the effective oxidative coupling, pioneering new aromatic ring activations was essential and several useful methodologies have been found for oxidizable arenes. The achievements regarding this objective obtained in our continuous research are herein summarized with classification of the aromatic ring activation strategies.

  15. Quality and aromatic sensory descriptors (mainly fresh and dry fruit character) of Spanish red wines can be predicted from their aroma-active chemical composition.

    PubMed

    San-Juan, Felipe; Ferreira, Vicente; Cacho, Juan; Escudero, Ana

    2011-07-27

    A satisfactory model explaining quality could be built in a set of 25 high quality Spanish red wines, by aroma-active chemical composition. The quality of the wines was positively correlated with the wine content in fruity esters, acids, enolones, and wood derived compounds, and negatively with phenylacetaldehyde, acetic acid, methional, and 4-ethylphenol. Wine fruitiness was demonstrated to be positively related not only to the wine content on fruity esters and enolones, but to wine volatile fatty acids. Fruitiness is strongly suppressed by 4-ethylphenol, acetic acid, phenylacetaldehyde, and methional, this involved in the perception of dry-fruit notes. Sensory effects were more intense in the presence of β-damascenone and β-ionone. A satisfactory model explaining animal notes could be built. Finally, the vegetal character of this set of wines could be related to the combined effect of dimethylsulfide (DMS), 1-hexanol, and methanethiol.

  16. Growth and survival of Pseudomonas aeruginosa in some aromatic waters.

    PubMed

    Ibrahim, Y K; Ogunmodede, M S

    1991-01-01

    The ability of some aromatic waters at the in-use concentrations to enhance or inhibit the growth of microorganisms was determined by the antimicrobial preservative challenge method. Anise, chloroform, cinnamon, clove, dill, lemon, peppermint and rose waters were challenged with Ps. aeruginosa. Levels of the surviving cells at different times were determined by the pour plate method. The antimicrobial effect of the corresponding undiluted aromatic oils against Ps. aeruginosa was determined by the cup-plate method. Results showed that cinnamon water possesses profound and useful preservative activity against Ps. aeruginosa. The inhibitory effect of anise, chloroform and rose waters on Ps. aeruginosa is not much pronounced. Similarly, clove, dill and peppermint waters exhibited no significant preservative actions. Lemon water was found to enhance the growth of Ps. aeruginosa. The survival pattern of Ps. aeruginosa in the majority of the aromatic waters conforms with the antimicrobial actions of their undiluted oils.

  17. Synthesis and biological evaluation of 12 allenic aromatic ethers.

    PubMed

    Wang, San-Yong; Mao, Wei-Wei; She, Zhi-Gang; Li, Chun-Rong; Yang, Ding-Qiao; Lin, Yong-Cheng; Fu, Li-Wu

    2007-05-15

    Twelve allenic aromatic ethers, some of them are natural products isolated from the mangrove fungus Xylaria sp. 2508 in the South China Sea, were synthesized. Their antitumor activities against KB and KBv200 cells were determined. All these compounds demonstrated cytotoxic potential, ranging from weak to strong activity. The analysis of structure-activity relationships suggested that the introduction of allenic moiety could generate or enhance cytotoxicity of these phenol compounds.

  18. MICROBIAL METABOLISM OF AROMATIC COMPOUNDS I.

    PubMed Central

    Tabak, Henry H.; Chambers, Cecil W.; Kabler, Paul W.

    1964-01-01

    Tabak, Henry H. (Robert A. Taft Sanitary Engineering Center, Cincinnati, Ohio), Cecil W. Chambers, and Paul W. Kabler. Microbial metabolism of aromatic carbon compounds. I. Decomposition of phenolic compounds and aromatic hydrocarbons by phenol-adapted bacteria. J. Bacteriol. 87:910–919. 1964.—Bacteria from soil and related environments were selected or adapted to metabolize phenol, hydroxy phenols, nitrophenols, chlorophenols, methylphenols, alkylphenols, and arylphenols when cultured in mineral salts media with the specific substrate as the sole source of carbon. A phenol-adapted culture (substrate-induced enzyme synthesis proven) was challenged in respirometric tests with 104 related compounds; probable significant oxidative activity occurred with 65. Dihydric phenols were generally oxidized; trihydric phenols were not. Cresols and dimethylphenols were oxidized; adding a chloro group increased resistance. Benzoic and hydroxybenzoic acids were oxidized; sulfonated, methoxylated, nitro, and chlorobenzoic acids were not; m-toluic acid was utilized but not the o- and p-isomers. Benzaldehyde and p-hydroxybenzaldehyde were oxidized. In general, nitro- and chloro-substituted compounds and the benzenes were difficult to oxidize. PMID:14137630

  19. Evaluation of 8-hydroxy-2'-deoxyguanosine (8-OHdG) adduct levels and DNA strand breaks in human peripheral blood lymphocytes exposed in vitro to polycyclic aromatic hydrocarbons with or without animal metabolic activation.

    PubMed

    Isabel, Rodríguez-Romero María; Sandra, Gómez-Arroyo; Rafael, Villalobos-Pietrini; Carmen, Martínez-Valenzuela; Josefina, Cortés-Eslava; del Carmen, Calderón-Ezquerro María; Rocío, García-Martínez; Francisco, Arenas-Huertero; Elena, Calderón-Segura María

    2012-04-01

    The polycyclic aromatic hydrocarbons (PAHs) dibenzo(a,h)anthracene, benzo(ghi)perylene, benzo(b)fluoranthene and benzo(a)pyrene have been identified in urban air from Mexico City and some of them are classified as human carcinogens. In the present study, human peripheral blood lymphocytes were exposed in vitro to different concentrations of PAHs with (+S9) or without (-S9) metabolic activation. The genotoxic and cytotoxic effects of each PAH were examined with an alkaline comet assay and trypan blue dye exclusion, and oxidative DNA damage was determined via the detection of 8-hydroxy-2'-deoxyguanosine (8-OhdG) adduct levels by enzyme-linked immunosorbent assay (ELISA). The DNA damage was evaluated with two genotoxicity parameters: the frequency of comets and the comet tail length. Concentrations of 20, 40, 80, 160 and 320 µM DB(a,h)A-S9; 20, 40, 80, 160 and 240 µM B(ghi)P-S9; 20, 30, 40, 60 and 80 µM B(b)F-S9; and 80 µM B(a)P-S9 for 24 h induced a small but significant increase in the means of comet frequency, in the tail length and in the 8-oHDg levels in relation to the control (0.5% DMSO-S9). However, all PAHs+S9 produced a more significant increase in DNA strand breaks and the level of 8-OHdG compared with the control (0.5% DMSO+S9), with a concentration-effect relationship. The viability of lymphocytes exposed to all PAHs-S9 and PAHs+S9 was not modified compared with the control. The results of this study demonstrate that the comet and ELISA are rapid, suitable and sensitive methods to detect in vitro PAH-induced DNA damage in human peripheral lymphocytes. PMID:21999439

  20. Evaluation of 8-hydroxy-2'-deoxyguanosine (8-OHdG) adduct levels and DNA strand breaks in human peripheral blood lymphocytes exposed in vitro to polycyclic aromatic hydrocarbons with or without animal metabolic activation.

    PubMed

    Isabel, Rodríguez-Romero María; Sandra, Gómez-Arroyo; Rafael, Villalobos-Pietrini; Carmen, Martínez-Valenzuela; Josefina, Cortés-Eslava; del Carmen, Calderón-Ezquerro María; Rocío, García-Martínez; Francisco, Arenas-Huertero; Elena, Calderón-Segura María

    2012-04-01

    The polycyclic aromatic hydrocarbons (PAHs) dibenzo(a,h)anthracene, benzo(ghi)perylene, benzo(b)fluoranthene and benzo(a)pyrene have been identified in urban air from Mexico City and some of them are classified as human carcinogens. In the present study, human peripheral blood lymphocytes were exposed in vitro to different concentrations of PAHs with (+S9) or without (-S9) metabolic activation. The genotoxic and cytotoxic effects of each PAH were examined with an alkaline comet assay and trypan blue dye exclusion, and oxidative DNA damage was determined via the detection of 8-hydroxy-2'-deoxyguanosine (8-OhdG) adduct levels by enzyme-linked immunosorbent assay (ELISA). The DNA damage was evaluated with two genotoxicity parameters: the frequency of comets and the comet tail length. Concentrations of 20, 40, 80, 160 and 320 µM DB(a,h)A-S9; 20, 40, 80, 160 and 240 µM B(ghi)P-S9; 20, 30, 40, 60 and 80 µM B(b)F-S9; and 80 µM B(a)P-S9 for 24 h induced a small but significant increase in the means of comet frequency, in the tail length and in the 8-oHDg levels in relation to the control (0.5% DMSO-S9). However, all PAHs+S9 produced a more significant increase in DNA strand breaks and the level of 8-OHdG compared with the control (0.5% DMSO+S9), with a concentration-effect relationship. The viability of lymphocytes exposed to all PAHs-S9 and PAHs+S9 was not modified compared with the control. The results of this study demonstrate that the comet and ELISA are rapid, suitable and sensitive methods to detect in vitro PAH-induced DNA damage in human peripheral lymphocytes.

  1. Polycyclic aromatic hydrocarbon (PAH)-mediated upregulation of hepatic microRNA-181 family promotes cancer cell migration by targeting MAPK phosphatase-5, regulating the activation of p38 MAPK

    SciTech Connect

    Song, Mi-Kyung; Park, Yong-Keun; Ryu, Jae-Chun

    2013-11-15

    Growing evidence indicates that changes in microRNA (miRNA) expression in cancer induced by chemical carcinogens play an important role in cancer development and progression by regulating related genes. However, the mechanisms underlying miRNA involvement in hepatocarcinogenesis induced by polycyclic aromatic hydrocarbons (PAHs) remain unclear. Thus, the identification of aberrant miRNA expression during PAH-induced cancer cell migration will lead to a better understanding of the substantial role of miRNAs in cancer progression. In the present study, miRNA expression profiling showed significant upregulation of miR-181a, -181b, and -181d in human hepatocellular carcinoma cells (HepG2 line) exposed to benzo[a]anthracene (BA) and benzo[k]fluoranthene (BF). MAPK phosphatase-5 (MKP-5), a validated miR-181 target that deactivates MAPKs, was markedly suppressed while phosphorylation of p38 MAPK was increased after BA and BF exposure. The migration of HepG2 cells, observed using the scratch wound-healing assay, also increased in a dose-dependent manner. Depletion of miR-181 family members by miRNA inhibitors enhanced the expression of MKP-5 and suppressed the phosphorylation of p38 MAPK. Furthermore, the depletion of the miR-181 family inhibited cancer cell migration. Based on these results, we conclude that the miR-181 family plays a critical role in PAH-induced hepatocarcinogenesis by targeting MKP-5, resulting in the regulation of p38 MAPK activation. - Highlights: • We found significant upregulation of miR-181 family in HCC exposed to BA and BF. • We identified the MKP-5 as a putative target of miR-181 family. • MKP-5 was suppressed while p-P38 was increased after BA and BF exposure. • The migration of HepG2 cells increased in a dose-dependent manner.

  2. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, Jr., Lawrence A.; Arganbright, Robert P.; Hearn, Dennis

    1993-01-01

    Aromatic compounds are alkylated in a catalytic distillation, wherein the catalyst structure also serves as a distillation component by contacting the aromatic compound with a C.sub.2 to C.sub.10 olefin in the catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 80.degree. C. to 500.degree. C., using as the catalyst a mole sieve characterized as acidic or an acidic cation exchange resin. For example, ethyl benzene is produced by feeding ethylene to about the mid point of the catalyst bed while benzene is conveniently added through the reflux in molar excess to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene in the bottoms.

  3. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, Jr., Lawrence A.

    1989-01-01

    Aromatic compounds are alkylated in a catalytic distillation, wherein the catalyst structure also serves as a distillation component by contacting the aromatic compound with a C.sub.2 to C.sub.10 olefin in the catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 80.degree. C. to 500.degree. C., using as the catalyst a mole sieve characterized as acidic or an acidic cation exchange resin. For example, ethyl benzene is produced by feeding ethylene below the catalyst bed while benzene is conveniently added through the reflux in molar excess to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene in the bottoms.

  4. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, L.A. Jr.; Arganbright, R.P.; Hearn, D.

    1993-09-07

    Aromatic compounds are alkylated in a catalytic distillation, wherein the catalyst structure also serves as a distillation component by contacting the aromatic compound with a C[sub 2] to C[sub 10] olefin in the catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 80 C to 500 C, using as the catalyst a molecular sieve characterized as acidic or an acidic cation exchange resin. For example, ethyl benzene is produced by feeding ethylene to about the mid point of the catalyst bed while benzene is conveniently added through the reflux in molar excess to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene in the bottoms. 1 figures.

  5. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, Jr., Lawrence A.; Arganbright, Robert P.; Hearn, Dennis

    1994-01-01

    Aromatic compounds are alkylated in a catalytic distillation, wherein the catalyst structure also serves as a distillation component by contacting the aromatic compound with a C.sub.2 to C.sub.10 olefin in the catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 80.degree. C. to 500.degree. C., using as the catalyst a mole sieve characterized as acidic or an acidic cation exchange resin. For example, ethyl benzene is produced by feeding ethylene below the catalyst bed while benzene is conveniently added through the reflux in molar excess to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene in the bottoms.

  6. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, L.A. Jr.

    1989-07-18

    Aromatic compounds are alkylated in a catalytic distillation, wherein the catalyst structure also serves as a distillation component by contacting the aromatic compound with a C[sub 2] to C[sub 10] olefin in the catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 80 C to 500 C, using as the catalyst a mole sieve characterized as acidic or an acidic cation exchange resin. For example, ethyl benzene is produced by feeding ethylene below the catalyst bed while benzene is conveniently added through the reflux in molar excess to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene in the bottoms. 1 fig.

  7. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, L.A. Jr.; Arganbright, R.P.; Hearn, D.

    1994-06-14

    Aromatic compounds are alkylated in a catalytic distillation, wherein the catalyst structure also serves as a distillation component by contacting the aromatic compound with a C[sub 2] to C[sub 10] olefin in the catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 80 C to 500 C, using as the catalyst a molecular sieve characterized as acidic or an acidic cation exchange resin. For example, ethyl benzene is produced by feeding ethylene below the catalyst bed while benzene is conveniently added through the reflux in molar excess to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene in the bottoms. 1 fig.

  8. Multiple Functions of Aromatic-Carbohydrate Interactions in a Processive Cellulase Examined with Molecular Simulation*

    PubMed Central

    Payne, Christina M.; Bomble, Yannick J.; Taylor, Courtney B.; McCabe, Clare; Himmel, Michael E.; Crowley, Michael F.; Beckham, Gregg T.

    2011-01-01

    Proteins employ aromatic residues for carbohydrate binding in a wide range of biological functions. Glycoside hydrolases, which are ubiquitous in nature, typically exhibit tunnels, clefts, or pockets lined with aromatic residues for processing carbohydrates. Mutation of these aromatic residues often results in significant activity differences on insoluble and soluble substrates. However, the thermodynamic basis and molecular level role of these aromatic residues remain unknown. Here, we calculate the relative ligand binding free energy by mutating tryptophans in the Trichoderma reesei family 6 cellulase (Cel6A) to alanine. Removal of aromatic residues near the catalytic site has little impact on the ligand binding free energy, suggesting that aromatic residues immediately upstream of the active site are not directly involved in binding, but play a role in the glucopyranose ring distortion necessary for catalysis. Removal of aromatic residues at the entrance and exit of the Cel6A tunnel, however, dramatically impacts the binding affinity, suggesting that these residues play a role in chain acquisition and product stabilization, respectively. The roles suggested from differences in binding affinity are confirmed by molecular dynamics and normal mode analysis. Surprisingly, our results illustrate that aromatic-carbohydrate interactions vary dramatically depending on the position in the enzyme tunnel. As aromatic-carbohydrate interactions are present in all carbohydrate-active enzymes, these results have implications for understanding protein structure-function relationships in carbohydrate metabolism and recognition, carbon turnover in nature, and protein engineering strategies for biomass utilization. Generally, these results suggest that nature employs aromatic-carbohydrate interactions with a wide range of binding affinities for diverse functions. PMID:21965672

  9. Tough, Soluble, Aromatic, Thermoplastic Copolyimides

    NASA Technical Reports Server (NTRS)

    Bryant, Robert G. (Inventor)

    1998-01-01

    Tough, soluble, aromatic, thermoplastic copolyimides were prepared by reacting 4,4'-oxydiphthalic anhydride, 3,4,3',4'-biphenyltetracarboxylic dianhydride and 3,4'-oxydianiline. These copolyimides were found to be soluble in common amide solvents such as N,N'-dimethyl acetamide, N-methylpyrrolidinone, and dimethylformamide allowing them to be applied as the fully imidized copolymer and to be used to prepare a wide range of articles.

  10. The direct aromatization of methane

    SciTech Connect

    Marcelin, G.; Oukaci, R.; Migone, R.A.; Kazi, A.M.

    1995-12-31

    The thermal decomposition of methane shows significant potential as a process for the production of higher unsaturated and aromatic hydrocarbons when the extent of the reaction is limited. Thermodynamic calculations have shown that when the reaction is limited to the formation of C{sub 2} to C{sub 10} products, yields of aromatics can exceed 40% at temperatures of 1200{degrees}C. Preliminary experiments have shown that when the reaction is limited to the formation of C{sub 2} to C{sub 10} products, yields of aromatics can exceed 40% at temperatures of 1200{degrees}C. Preliminary experiments have shown that cooling the product and reacting gases as the reaction proceeds can significantly reduce or eliminate the formation of solid carbon and heavier (C{sub 10+}) materials. Much work remains to be done in optimizing the quenching process and this is one of the goals of this program. Means to lower the temperature of the reaction are being studied as this result in a more feasible commercial process due to savings realized in energy and material of construction costs. The use of free-radical generators and catalysts will be investigated as a means of lowering the reaction temperature thus allowing faster quenching. It is highly likely that such studies will lead to a successful direct methane to higher hydrocarbon process.

  11. Anaerobic metabolism of phthalate and other aromatic compounds by a denitrifying bacterium. [Pseudomonas sp

    SciTech Connect

    Nozawa, T.; Maruyama, Y. )

    1988-12-01

    The anaerobic metabolism of phthalate and other aromatic compounds by the denitrifying bacterium Pseudomonas sp. strain P136 was studied. Benzoate, cyclohex-1-ene-carboxylate, 2-hydroxycyclohexanecarboxylate, and pimelate were detected as predominant metabolic intermediates during the metabolism of three isomers of phthalate, m-hydroxybenzoate, p-hydroxybenzoate, and cyclohex-3-ene-carboxylate. Inducible acyl-coeznyme A synthetase activities for phthalates, benzoate, cyclohex-1-ene-carboxylate, and cyclohex-3-ene-carboxylate were detected in the cells grown on aromatic compounds. Simultaneous adaptation to these aromatic compounds also occurred. A similar phenomenon was observed in the aerobic metabolism of aromatic compounds by this strain. A new pathway for the anaerobic metabolism of phthalate and a series of other aromatic compounds by this strain was proposed. Some properties of the regulation of this pathway were also discussed.

  12. A Facile Solid‐Phase Route to Renewable Aromatic Chemicals from Biobased Furanics

    PubMed Central

    Thiyagarajan, Shanmugam; Genuino, Homer C.; van der Waal, Jan C.; Weckhuysen, Bert M.; van Haveren, Jacco

    2015-01-01

    Abstract Renewable aromatics can be conveniently synthesized from furanics by introducing an intermediate hydrogenation step in the Diels–Alder (DA) aromatization route, to effectively block retro‐DA activity. Aromatization of the hydrogenated DA adducts requires tandem catalysis, using a metal‐based dehydrogenation catalyst and solid acid dehydration catalyst in toluene. Herein it is demonstrated that the hydrogenated DA adducts can instead be conveniently converted into renewable aromatics with up to 80 % selectivity in a solid‐phase reaction with shorter reaction times using only an acidic zeolite, that is, without solvent or dehydrogenation catalyst. Hydrogenated adducts from diene/dienophile combinations of (methylated) furans with maleic anhydride are efficiently converted into renewable aromatics with this new route. The zeolite H‐Y was found to perform the best and can be easily reused after calcination. PMID:26684008

  13. A Facile Solid-Phase Route to Renewable Aromatic Chemicals from Biobased Furanics.

    PubMed

    Thiyagarajan, Shanmugam; Genuino, Homer C; van der Waal, Jan C; de Jong, Ed; Weckhuysen, Bert M; van Haveren, Jacco; Bruijnincx, Pieter C A; van Es, Daan S

    2016-01-22

    Renewable aromatics can be conveniently synthesized from furanics by introducing an intermediate hydrogenation step in the Diels-Alder (DA) aromatization route, to effectively block retro-DA activity. Aromatization of the hydrogenated DA adducts requires tandem catalysis, using a metal-based dehydrogenation catalyst and solid acid dehydration catalyst in toluene. Herein it is demonstrated that the hydrogenated DA adducts can instead be conveniently converted into renewable aromatics with up to 80% selectivity in a solid-phase reaction with shorter reaction times using only an acidic zeolite, that is, without solvent or dehydrogenation catalyst. Hydrogenated adducts from diene/dienophile combinations of (methylated) furans with maleic anhydride are efficiently converted into renewable aromatics with this new route. The zeolite H-Y was found to perform the best and can be easily reused after calcination. PMID:26684008

  14. Noncomparative scaling of aromaticity through electron itinerancy

    SciTech Connect

    Paul, Satadal; Goswami, Tamal; Misra, Anirban

    2015-10-15

    Aromaticity is a multidimensional concept and not a directly observable. These facts have always stood in the way of developing an appropriate theoretical framework for scaling of aromaticity. In the present work, a quantitative account of aromaticity is developed on the basis of cyclic delocalization of π-electrons, which is the phenomenon leading to unique features of aromatic molecules. The stabilization in molecular energy, caused by delocalization of π-electrons is obtained as a second order perturbation energy for archetypal aromatic systems. The final expression parameterizes the aromatic stabilization energy in terms of atom to atom charge transfer integral, onsite repulsion energy and the population of spin orbitals at each site in the delocalized π-electrons. An appropriate computational platform is framed to compute each and individual parameter in the derived equation. The numerical values of aromatic stabilization energies obtained for various aromatic molecules are found to be in close agreement with available theoretical and experimental reports. Thus the reliable estimate of aromaticity through the proposed formalism renders it as a useful tool for the direct assessment of aromaticity, which has been a long standing problem in chemistry.

  15. Noncomparative scaling of aromaticity through electron itinerancy

    NASA Astrophysics Data System (ADS)

    Paul, Satadal; Goswami, Tamal; Misra, Anirban

    2015-10-01

    Aromaticity is a multidimensional concept and not a directly observable. These facts have always stood in the way of developing an appropriate theoretical framework for scaling of aromaticity. In the present work, a quantitative account of aromaticity is developed on the basis of cyclic delocalization of π-electrons, which is the phenomenon leading to unique features of aromatic molecules. The stabilization in molecular energy, caused by delocalization of π-electrons is obtained as a second order perturbation energy for archetypal aromatic systems. The final expression parameterizes the aromatic stabilization energy in terms of atom to atom charge transfer integral, onsite repulsion energy and the population of spin orbitals at each site in the delocalized π-electrons. An appropriate computational platform is framed to compute each and individual parameter in the derived equation. The numerical values of aromatic stabilization energies obtained for various aromatic molecules are found to be in close agreement with available theoretical and experimental reports. Thus the reliable estimate of aromaticity through the proposed formalism renders it as a useful tool for the direct assessment of aromaticity, which has been a long standing problem in chemistry.

  16. Evolution of aromatic prenyltransferases in the biosynthesis of indole derivatives.

    PubMed

    Li, Shu-Ming

    2009-01-01

    A series of putative indole prenyltransferase genes could be identified in the genome sequences of different fungal strains including Aspergillus fumigatus and Neosartorya fischeri. The gene products show significant sequence similarities to dimethylallyltryptophan synthases from different fungi. We have cloned and overexpressed seven of these genes, fgaPT1, fgaPT2, ftmPT1, ftmPT2, 7-dmats, cdpNPT and anaPT in Escherichia coli and Saccharomyces cerevisiae. The overproduced enzymes were characterised biochemically. Three additional indole prenyltransferases, DmaW-Cs, TdiB and MaPT were also identified and characterised in the last years. Sequence analysis and comparison with known aromatic prenyltransferases as well as biochemical investigation revealed that these enzymes belong to a group of aromatic prenyltransferases. The characterised prenyltransferases are soluble proteins, catalyse different prenyl transfer reactions on indole moieties of various substrates and do not require divalent metal ions for their prenyl transfer reactions. In addition, indole prenyltransferases carry tryptophan aminopeptidase activity, which strengths their relationship in the evolution. These properties differ clearly from membrane-bound aromatic prenyltransferases from different sources and soluble prenyltransferases from bacteria. All of the indole prenyltransferases accepted only dimethylallyl diphosphate as prenyl donor. On the other hand, they showed broad substrate specificity towards their aromatic substrates. Diverse simple tryptophan derivatives and tryptophan-containing cyclic dipeptides were accepted by these enzymes, providing a strategy for convenient production of biologically active substances, e.g. by chemoenzymatic synthesis.

  17. Influence of carbonization methods on the aromaticity of pyrogenic dissolved organic carbon

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dissolved organic carbon (DOC) components of soil amendments such as biochar will influence the fundamental soil chemistry including the metal speciation, nutrient availability, and microbial activity. Quantitative correlation is necessary between (i) pyrogenic DOC components of varying aromaticity...

  18. COMPUTATIONAL METHODS FOR STUDYING THE INTERACTION BETWEEN POLYCYCLIC AROMATIC HYDROCARBONS AND BIOLOGICAL MACROMOLECULES

    EPA Science Inventory

    Computational Methods for Studying the Interaction between Polycyclic Aromatic Hydrocarbons and Biological Macromolecules .

    The mechanisms for the processes that result in significant biological activity of PAHs depend on the interaction of these molecules or their metabol...

  19. Highly active and highly selective aromatization catalyst

    SciTech Connect

    Santilli, D.S.; Long, J.J.; Lewis, R.T.

    1987-10-06

    This patent describes a reforming catalyst comprising an L zeolite containing platinum metal and at least one promoter metal selected from the group consisting of iron, cobalt, titanium, and rare earth metal. The catalyst has a platinum to promoter metal mole ratio of less than 10:1. The patent also includes a method of preparing the reforming catalyst of claim 1, comprising steps of: (a) forming an aqueous solution of alkali hydroxide, aluminum hydroxide, and ferric salt; (b) combining the solution with an aqueous solution of silica to form a thickening gel in a mother liquor; (c) heating the thickening gel to form an L zeolite; (d) cooling the gel containing the L zeolite; (e) decanting the mother liquor from the gel; (f) filtering the L zeolite from the gel; (g) washing the filtered L zeolite; (h) drying the washed L zeolite; (i) adding platinum to the dried L zeolite to form a catalyst; (j) drying the catalyst; and (k) calcining the dried catalyst.

  20. Production of alkyl-aromatics from light oxygenates over zeolite catalysts for bio-oil refining

    NASA Astrophysics Data System (ADS)

    Hoang, Trung Q.

    Upgrading of light oxygenates derived from biomass conversion, such as propanal and glycerol, to more valuable aromatics for biofuels has been demonstrated on zeolite catalysts. Aromatics with a high ratio of C 9/(C8+C7) and little benzene are produced at much higher yield from oxygenates than from olefins at mild conditions over HZSM-5. It is proposed that C9 aromatics are predominantly produced via acid-catalyzed aldol condensation. This reaction pathway is different from the pathway of propylene and other hydrocarbon aromatization that occurs via a hydrocarbon pool at more severe conditions with major aromatic products C6 and C7. In fact, investigation on the effect of crystallite size HZSM-5 has shown a higher ratio of C9/(C8+C 7) aromatics on small crystallite. This is due to faster removal of products from the shorter diffusion path length. As a result, a longer catalyst lifetime, less isomerization, and less cracking were observed on small crystallites. Beside crystallite size, pore geometry of zeolites was also found to significantly affect aromatic production for both conversion of propanal and glycerol. It is shown that the structure of the HZSM-22, with a one-dimensional and narrower channel system, restricts the formation of aromatics. In contrast, a higher yield of aromatic products is observed over HZSM-5 with its three-dimensional channel system. By increasing channel dimension and connectivity of the channels, increasing catalyst activity was also observed due to more accessible acid sites. It was also found that glycerol is highly active for dehydration on zeolites to produce high yields of acrolein (propenal), a high value chemical. To maximize aromatics from glycerol conversion, HZSM-5 and HY were found to be effective. A two-bed reactor of Pd/ZnO and HZSM-5 was used to first deoxygenate/hydrogenate glycerol over Pd/ZnO to intermediate oxygenates that can further aromatize on HZSM-5. The end results are very promising with significant improvement

  1. The biodegradation vs. biotransformation of fluorosubstituted aromatics.

    PubMed

    Kiel, Martina; Engesser, Karl-Heinrich

    2015-09-01

    Fluoroaromatics are widely and--in recent years--increasingly used as agrochemicals, starting materials for chemical syntheses and especially pharmaceuticals. This originates from the special properties the carbon-fluorine bond is imposing on organic molecules. Hence, fluoro-substituted compounds more and more are considered to be important potential environmental contaminants. On the other hand, the microbial potentials for their transformation and mineralization have received less attention in comparison to other haloaromatics. Due to the high electronegativity of the fluorine atom, its small size, and the extraordinary strength of the C-F bond, enzymes and mechanisms known to facilitate the degradation of chloro- or bromoarenes are not necessarily equally active with fluoroaromatics. Here, we review the literature on the microbial degradation of ring and side-chain fluorinated aromatic compounds under aerobic and anaerobic conditions, with particular emphasis being placed on the mechanisms of defluorination reactions.

  2. Extensive theoretical studies on two new members of the FOX-7 family: 5-(dinitromethylene)-1,4-dinitramino-tetrazole and 1,1'-dinitro-4,4'-diamino-5,5'-bitetrazole as energetic compounds.

    PubMed

    He, Piao; Zhang, Jian-Guo; Wang, Kun; Yin, Xin; Jin, Xin; Zhang, Tong-Lai

    2015-02-28

    Two novel compounds 5-(dinitromethylene)-1,4-dinitramino-tetrazole (DNAT) and 1,1'-dinitro-4,4'-diamino-5,5'-bitetrazole (DNABT) were suggested to be potential candidates of high energy density materials (HEDMs). The optimized geometry, NBO charges and electronic density, HOMO-LUMO, electrostatic potential on the surface of molecules, the IR spectrum and thermochemical parameters were calculated for inspecting the electronic structure properties at B3LYP/6-311++G** level of theory. Meanwhile, the solid states of DNAT and DNABT were studied using the crystal packing models by the plane-wave periodic local-density approximation density functional theory. Four stable polymorphous cells have been found including P212121, P21/c, P1̄ and Pbca, assigned to the orthorhombic, monoclinic and triclinic lattice systems. In addition, properties such as density, enthalpy of formation and detonation performance have also been predicted. As a result, the detonation velocity and pressure of two compounds are found to be very remarkable (DNAT: D = 9.17 km s(-1), P = 39.23 GPa; DNABT: D = 9.53 km s(-1), P = 40.92 GPa). Considering the tetrazole rings with energetic groups and the insensitive fragment of FOX-7, high positive heat of formation (583.50 kJ mol(-1) and 1081.39 kJ mol(-1)) and eminent performance render DNAT and DNABT to be very promising powerful energetically insensitive compounds. This work provides theoretical support for further experimental synthesis.

  3. Synthesis, characterization and thermolysis studies on 3,7-dinitro-1,3,5,7-tetraazabicyclo[3,3,1]nonane (DPT): A key precursor in the synthesis of most powerful benchmark energetic materials (RDX/HMX) of today.

    PubMed

    Radhakrishnan, S; Talawar, M B; Venugopalan, S; Narasimhan, V L

    2008-04-15

    This paper reports studies undertaken on 3,7-dinitro-1,3,5,7-tetraazabicyclo[3,3,1]nonane (DPT). The synthesis of DPT was carried out by the nitration of hexamine based on the lines of reported method with minor modification. DPT was characterized by elemental analysis, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and (1)H nuclear magnetic resonance (NMR) techniques. Thermal stability of DPT was studied using thermogravimetry (TG) and differential scanning calorimetry (DSC). The thermal analysis studies revealed that DPT undergoes decomposition at 211 degrees C. Decomposition of DPT using TG-FTIR indicated the evolution of carbon dioxide, water and oxides of nitrogen as main gaseous products. The electrochemical behavior of DPT was studied using cyclic voltammetric (CV) studies. The experimentally determined sensitivity parameters indicated the insensitive nature of DPT towards external stimuli. The performance parameters of DPT, RDX and HMX have been computed using Linear Output Thermodynamic User Friendly Software for Energetic Systems (LOTUSES) code. The predicted properties of DPT are interesting and important from the point of process technology and/or safety. The work reported in this paper enriches the existing scanty research and development data on one of the key precursor used for synthesis of important high energy materials (HEMs).

  4. A study of dinitro-bis-1,2,4-triazole-1,1'-diol and derivatives: design of high-performance insensitive energetic materials by the introduction of N-oxides.

    PubMed

    Dippold, Alexander A; Klapötke, Thomas M

    2013-07-01

    In this contribution we report on the synthesis and full structural as well as spectroscopic characterization of 3,3'-dinitro-5,5'-bis-1,2,4-triazole-1,1'-diol and nitrogen-rich salts thereof. The first synthesis and characterization of an energetic 1-hydroxy-bistriazole in excellent yields and high purity is presented. This simple and straightforward method of N-oxide introduction in triazole compounds using commercially available oxone improves the energetic properties and reveals a straightforward synthetic pathway toward novel energetic 1,2,4-triazole derivatives. X-ray crystallographic measurements were performed and deliver insight into structural characteristics and strong intermolecular interactions. The standard enthalpies of formation were calculated for all compounds at the CBS-4 M level of theory, revealing highly positive heats of formation for all compounds. The energetic properties of all compounds (detonation velocity, pressure, etc.) were calculated using the EXPLO5.05 program, and the ionic derivatives show superior performance in comparison to the corresponding compounds bearing no N-oxide. All substances were characterized in terms of sensitivities (impact, friction, electrostatic) and thermal stabilities, and the ionic derivatives were found to be high thermally stable, insensitive compounds that are exceedingly powerful but safe to handle and prepare.

  5. Quantum transport through aromatic molecules

    SciTech Connect

    Ojeda, J. H.; Rey-González, R. R.; Laroze, D.

    2013-12-07

    In this paper, we study the electronic transport properties through aromatic molecules connected to two semi-infinite leads. The molecules are in different geometrical configurations including arrays. Using a nearest neighbor tight-binding approach, the transport properties are analyzed into a Green's function technique within a real-space renormalization scheme. We calculate the transmission probability and the Current-Voltage characteristics as a function of a molecule-leads coupling parameter. Our results show different transport regimes for these systems, exhibiting metal-semiconductor-insulator transitions and the possibility to employ them in molecular devices.

  6. Solid Phase Synthesis of Helically Folded Aromatic Oligoamides.

    PubMed

    Dawson, S J; Hu, X; Claerhout, S; Huc, I

    2016-01-01

    Aromatic amide foldamers constitute a growing class of oligomers that adopt remarkably stable folded conformations. The folded structures possess largely predictable shapes and open the way toward the design of synthetic mimics of proteins. Important examples of aromatic amide foldamers include oligomers of 7- or 8-amino-2-quinoline carboxylic acid that have been shown to exist predominantly as well-defined helices, including when they are combined with α-amino acids to which they may impose their folding behavior. To rapidly iterate their synthesis, solid phase synthesis (SPS) protocols have been developed and optimized for overcoming synthetic difficulties inherent to these backbones such as low nucleophilicity of amine groups on electron poor aromatic rings and a strong propensity of even short sequences to fold on the solid phase during synthesis. For example, acid chloride activation and the use of microwaves are required to bring coupling at aromatic amines to completion. Here, we report detailed SPS protocols for the rapid production of: (1) oligomers of 8-amino-2-quinolinecarboxylic acid; (2) oligomers containing 7-amino-8-fluoro-2-quinolinecarboxylic acid; and (3) heteromeric oligomers of 8-amino-2-quinolinecarboxylic acid and α-amino acids. SPS brings the advantage to quickly produce sequences having varied main chain or side chain components without having to purify multiple intermediates as in solution phase synthesis. With these protocols, an octamer could easily be synthesized and purified within one to two weeks from Fmoc protected amino acid monomer precursors. PMID:27586338

  7. Biodegradation of aromatic hydrocarbons in an extremely acidic environment

    SciTech Connect

    Stapleton, R.D.; Savage, D.C.; Sayler, G.S.; Stacey, G.

    1998-11-01

    The potential for biodegradation of aromatic hydrocarbons was evaluated in soil samples recovered along gradients of both contaminant levels and pH values existing downstream of a long-term coal pile storage basin. pH values for areas greatly impacted by runoff from the storage basin were 2.0. Even at such a reduced pH, the indigenous microbial community was metabolically active, showing the ability to oxidize more than 40% of the parent hydrocarbons, naphthalene and toluene, to carbon dioxide and water. Treatment of the soil samples with cycloheximide inhibited mineralization of the aromatic substrates. DNA hybridization analysis indicated that whole-community nucleic acids recovered from these samples did not hybridize with genes, such as nahA, nahG, nahH, todC1C2, and tomA, that encode common enzymes from neutrophilic bacteria. Since these data suggested that the degradation of aromatic compounds may involve a microbial consortium instead of individual acidophilic bacteria, experiments using microorganisms isolated from these samples were initiated. While no defined mixed cultures were able to evolve {sup 14}CO{sub 2} from labeled substrates in these mineralization experiments, an undefined mixed culture including a fungus, a yeast, and several bacteria successfully metabolized approximately 27% of supplied naphthalene after 1 week. This study shows that biodegradation of aromatic hydrocarbons can occur in environments with extremely low pH values.

  8. Genomic and molecular mechanisms for efficient biodegradation of aromatic dye.

    PubMed

    Sun, Su; Xie, Shangxian; Chen, Hu; Cheng, Yanbing; Shi, Yan; Qin, Xing; Dai, Susie Y; Zhang, Xiaoyu; Yuan, Joshua S

    2016-01-25

    Understanding the molecular mechanisms for aromatic compound degradation is crucial for the development of effective bioremediation strategies. We report the discovery of a novel phenomenon for improved degradation of Direct Red 5B azo dye by Irpex lacteus CD2 with lignin as a co-substrate. Transcriptomics analysis was performed to elucidate the molecular mechanisms of aromatic degradation in white rot fungus by comparing dye, lignin, and dye/lignin combined treatments. A full spectrum of lignin degradation peroxidases, oxidases, radical producing enzymes, and other relevant components were up-regulated under DR5B and lignin treatments. Lignin induced genes complemented the DR5B induced genes to provide essential enzymes and redox conditions for aromatic compound degradation. The transcriptomics analysis was further verified by manganese peroxidase (MnP) protein over-expression, as revealed by proteomics, dye decolorization assay by purified MnP and increased hydroxyl radical levels, as indicated by an iron reducing activity assay. Overall, the molecular and genomic mechanisms indicated that effective aromatic polymer degradation requires synergistic enzymes and radical-mediated oxidative reactions to form an effective network of chemical processes. This study will help to guide the development of effective bioremediation and biomass degradation strategies.

  9. Heterogeneous Reactions of Polycyclic Aromatic Hydrocarbons on Atmospheric and Terrestrial Surfaces

    NASA Astrophysics Data System (ADS)

    Simonich, S. L.

    2014-12-01

    The heterogeneous reactions of five higher molecular weight polycyclic aromatic hydrocarbons (PAHs), benzo[a]pyrene-d12 (BaP-d12), benzo(k)fluoranthene-d12 (BkF-d12), benzo[g,h,i]perylene-d12 (BghiP-d12), dibenzo(a,i)pyrene-d14 (DBaiP-d14), and dibenzo[a,l]pyrene (DalP), with NO2, NO3/N2O5, O3, and OH radicals were investigated in a 7000 L indoor Teflon chamber. Quartz fiber filters (QFF) were used as the reaction surface and substrate and the analyses of parent PAHs and Nitro-PAH (NPAH) products was conducted using electron impact gas chromatographic mass spectrometry (GC/MS) and negative chemical ionization GC/MS. In parallel to the laboratory experiments, a theoretical study was conducted to assist in determining the formation of NPAH isomers based on the OH-radical initiated reaction. The thermodynamic stability of OH-PAH intermediates was used to indicate the position of highest electron density and the most stable NPAH products were synthesized to confirm their identity. NO2 and NO3/N2O5 were the most effective oxidizing agents in transforming PAHs deposited on filters to NPAHs, under the experimental conditions. Reaction of BaP-d12, BkF-d12 and BghiP-d12 resulted in the formation of several mono-nitro PAH isomer product, while the reaction of DalP and DaiP-d14 resulted in the formation of only one mono-nitro PAH isomer product. The direct-acting mutagenicity of the products increased the most after NO3/N2O5 exposure, particularly for BkF-d12 in which the formation of dinitro- PAHs was observed. In addition, the degradation of particulate matter (PM)-bound PAHs by heterogeneous reaction with OH radicals, O3, NO3/N2O5 was also studied. Ambient PM samples collected from Beijing, China and Riverside, California were exposed in an indoor chamber under simulated trans-Pacific atmospheric transport conditions and the formation of NPAHs was studied. NPAHs were most effectively formed during the NO3/N2O5 exposure and, for all exposures, there was no significant

  10. Synthesis and anti-inflammatory properties of some aromatic and heterocyclic aromatic curcuminoids.

    PubMed

    Khan, M Akram; El-Khatib, Riyad; Rainsford, K D; Whitehouse, M W

    2012-02-01

    A variety of novel aromatic and heterocyclic aromatic curcuminoids were synthesised, characterised and their anti-inflammatory activities (AIA) determined in vivo. Some of these compounds also were tested for inflammatory mediator production. The AIA of the main representatives of these compounds were assessed by oral administration to female Wistar rats using (a) acute carrageenan-induced paw oedema, (b) chronic adjuvant arthritis (therapeutic mode), and (c) anti-pyretic activity assessed in the yeast pyrexia. Gastric ulceration was determined in pre-inflamed rats. Natural curcumin showed modest aspirin-like anti-inflammatory activity which was enhanced when co-administered with the PGE(1) analogue misoprostol as a synergist. In contrast, four novel curcuminoids (RK-97, RK-103, RK-104 and RK-106) in which the bis-methoxy-phenyl group of curcumin was replaced with bis-dimethoxybutenolidyl-(ascorbate), bis-naphthyl, and bis-furanyl derivatives, respectively, had potent activity in the anti-arthritic assay with little gastric or systemic toxicity, compared with the vehicle-treated controls. Of the curcuminoids the furan RK-106 was the only compound to inhibit production of TNFα and IL-1β in a monocytic cell-line THP-1 in vitro. The inactivity of RK-106 on the production of PGE(2) may be related to its absence of gastrotoxicity. None of the curcuminoids exhibited anti-pyretic activity and this may also be related to its insensitivity to PGE(2). Thus, these novel curcuminoids, such as RK-106, may warrant the development of new low gastro-toxic anti-inflammatory agents with selective inhibitory activity of cytokine inflammatory mediators. PMID:22172598

  11. Genetics Home Reference: aromatic l-amino acid decarboxylase deficiency

    MedlinePlus

    ... aromatic l-amino acid decarboxylase deficiency aromatic l-amino acid decarboxylase deficiency Enable Javascript to view the expand/ ... PDF Open All Close All Description Aromatic l-amino acid decarboxylase (AADC) deficiency is an inherited disorder that ...

  12. Computer Simulations Reveal Multiple Functions for Aromatic Residues in Cellulase Enzymes (Fact Sheet)

    SciTech Connect

    Not Available

    2012-07-01

    NREL researchers use high-performance computing to demonstrate fundamental roles of aromatic residues in cellulase enzyme tunnels. National Renewable Energy Laboratory (NREL) computer simulations of a key industrial enzyme, the Trichoderma reesei Family 6 cellulase (Cel6A), predict that aromatic residues near the enzyme's active site and at the entrance and exit tunnel perform different functions in substrate binding and catalysis, depending on their location in the enzyme. These results suggest that nature employs aromatic-carbohydrate interactions with a wide variety of binding affinities for diverse functions. Outcomes also suggest that protein engineering strategies in which mutations are made around the binding sites may require tailoring specific to the enzyme family. Cellulase enzymes ubiquitously exhibit tunnels or clefts lined with aromatic residues for processing carbohydrate polymers to monomers, but the molecular-level role of these aromatic residues remains unknown. In silico mutation of the aromatic residues near the catalytic site of Cel6A has little impact on the binding affinity, but simulation suggests that these residues play a major role in the glucopyranose ring distortion necessary for cleaving glycosidic bonds to produce fermentable sugars. Removal of aromatic residues at the entrance and exit of the cellulase tunnel, however, dramatically impacts the binding affinity. This suggests that these residues play a role in acquiring cellulose chains from the cellulose crystal and stabilizing the reaction product, respectively. These results illustrate that the role of aromatic-carbohydrate interactions varies dramatically depending on the position in the enzyme tunnel. As aromatic-carbohydrate interactions are present in all carbohydrate-active enzymes, the results have implications for understanding protein structure-function relationships in carbohydrate metabolism and recognition, carbon turnover in nature, and protein engineering strategies for

  13. Beyond organic chemistry: aromaticity in atomic clusters.

    PubMed

    Boldyrev, Alexander I; Wang, Lai-Sheng

    2016-04-28

    We describe joint experimental and theoretical studies carried out collaboratively in the authors' labs for understanding the structures and chemical bonding of novel atomic clusters, which exhibit aromaticity. The concept of aromaticity was first discovered to be useful in understanding the square-planar unit of Al4 in a series of MAl4(-) bimetallic clusters that led to discoveries of aromaticity in many metal cluster systems, including transition metals and similar cluster motifs in solid compounds. The concept of aromaticity has been found to be particularly powerful in understanding the stability and bonding in planar boron clusters, many of which have been shown to be analogous to polycyclic aromatic hydrocarbons in their π bonding. Stimulated by the multiple aromaticity in planar boron clusters, a design principle has been proposed for stable metal-cerntered aromatic molecular wheels of the general formula, M@Bn(k-). A series of such borometallic aromatic wheel complexes have been produced in supersonic cluster beams and characterized experimentally and theoretically, including Ta@B10(-) and Nb@B10(-), which exhibit the highest coordination number in two dimensions.

  14. Aromatic Polyimides With Group VI Linkages

    NASA Technical Reports Server (NTRS)

    St. Clair, T. L.; Burks, H. D.; Ely, R. M.

    1983-01-01

    New polymer system combines thermal and solvent resistant properties of aromatic polyimides with processability of PPX polymers. PPX polymers include polyphenylene oxide, polyphenylene sulfide, and polyphenylene sulfone classes. Generally more processable by hot melt or thermoplastic techniques than aromatic polyimides. PPX systems more susceptible to attack by solvents and have lower glass transition temperatures than PI group.

  15. Metabolic Pathways for Degradation of Aromatic Hydrocarbons by Bacteria.

    PubMed

    Ladino-Orjuela, Guillermo; Gomes, Eleni; da Silva, Roberto; Salt, Christopher; Parsons, John R

    2016-01-01

    The aim of this review was to build an updated collection of information focused on the mechanisms and elements involved in metabolic pathways of aromatic hydrocarbons by bacteria. Enzymes as an expression of the genetic load and the type of electron acceptor available, as an environmental factor, were highlighted. In general, the review showed that both aerobic routes and anaerobic routes for the degradation of aromatic hydrocarbons are divided into two pathways. The first, named the upper pathways, entails the route from the original compound to central intermediate compounds still containing the aromatic ring but with the benzene nucleus chemically destabilized. The second, named the lower pathway, begins with ring de-aromatization and subsequent cleavage, resulting in metabolites that can be used by bacteria in the production of biomass. Under anaerobic conditions the five mechanisms of activation of the benzene ring described show the diversity of chemical reactions that can take place. Obtaining carbon and energy from an aromatic hydrocarbon molecule is a process that exhibits the high complexity level of the metabolic apparatus of anaerobic microorganisms. The ability of these bacteria to express enzymes that catalyze reactions, known only in non-biological conditions, using final electron acceptors with a low redox potential, is a most interesting topic. The discovery of phylogenetic and functional characteristics of cultivable and noncultivable hydrocarbon degrading bacteria has been made possible by improvements in molecular research techniques such as SIP (stable isotope probing) tracing the incorporation of (13)C, (15)N and (18)O into nucleic acids and proteins. Since many metabolic pathways in which enzyme and metabolite participants are still unknown, much new research is required. Therefore, it will surely allow enhancing the known and future applications in practice.

  16. Molecular catalytic hydrogenation of aromatic hydrocarbons and hydrotreating of coal liquids.

    SciTech Connect

    Yang, Shiyong; Stock, L.M.

    1996-05-01

    This report presents the results of research on the development of new catalytic pathways for the hydrogenation of multiring aromatic hydrocarbons and the hydrotreating of coal liquids at The University of Chicago under DOE Contract No. DE-AC22-91PC91056. The work, which is described in three parts, is primarily concerned with the research on the development of new catalytic systems for the hydrogenation of aromatic hydrocarbons and for the improvement of the quality of coal liquids by the addition of dihydrogen. Part A discusses the activation of dihydrogen by very basic molecular reagents to form adducts that can facilitate the reduction of multiring aromatic hydrocarbons. Part B examines the hydrotreating of coal liquids catalyzed by the same base-activated dihydrogen complexes. Part C concerns studies of molecular organometallic catalysts for the hydrogenation of monocyclic aromatic hydrocarbons under mild conditions.

  17. Structural basis for the promiscuous biosynthetic prenylation of aromatic natural products

    PubMed Central

    Kuzuyama, Tomohisa; Noel, Joseph P.; Richard, Stéphane B.

    2010-01-01

    The anti-oxidant naphterpin is a natural product containing a polyketide-based aromatic core with an attached 10-carbon geranyl group derived from isoprenoid (terpene) metabolism1–3. Hybrid natural products such as naphterpin that contain 5-carbon (dimethylallyl), 10-carbon (geranyl) or 15-carbon (farnesyl) isoprenoid chains possess biological activities distinct from their non-prenylated aromatic precursors4. These hybrid natural products represent new anti-microbial, anti-oxidant, anti-inflammatory, anti-viral and anti-cancer compounds. A small number of aromatic prenyltransferases (PTases) responsible for prenyl group attachment have only recently been isolated and characterized5,6. Here we report the gene identification, biochemical characterization and high-resolution X-ray crystal structures of an architecturally novel aromatic PTase, Orf2 from Streptomyces sp. strain CL190, with substrates and substrate analogues bound. In vivo, Orf2 attaches a geranyl group to a 1,3,6,8-tetra-hydroxynaphthalene-derived polyketide during naphterpin biosynthesis. In vitro, Orf2 catalyses carbon–carbon-based and carbon–oxygen-based prenylation of a diverse collection of hydroxyl-containing aromatic acceptors of synthetic, microbial and plant origin. These crystal structures, coupled with in vitro assays, provide a basis for understanding and potentially manipulating the regio-specific prenylation of aromatic small molecules using this structurally unique family of aromatic PTases. PMID:15959519

  18. Measurement and prediction of aromatic solute distribution coefficients for aqueous-organic solvent systems. Final report

    SciTech Connect

    Campbell, J.R.; Luthy, R.G.

    1984-06-01

    Experimental and modeling activities were performed to assess techniques for measurement and prediction of distribution coefficients for aromatic solutes between water and immiscible organic solvents. Experiments were performed to measure distribution coefficients in both clean water and wastewater systems, and to assess treatment of a wastewater by solvent extraction. The theoretical portions of this investigation were directed towards development of techniques for prediction of solute-solvent/water distribution coefficients. Experiments were performed to assess treatment of a phenolic-laden coal conversion wastewater by solvent extraction. The results showed that solvent extraction for recovery of phenolic material offered several wastewater processing advantages. Distribution coefficients were measured in clean water and wastewater systems for aromatic solutes of varying functionality with different solvent types. It was found that distribution coefficients for these compounds in clean water systems were not statistically different from distribution coefficients determined in a complex coal conversion process wastewater. These and other aromatic solute distribution coefficient data were employed for evaluation of modeling techniques for prediction of solute-solvent/water distribution coefficients. Eight solvents were selected in order to represent various chemical classes: toluene and benzene (aromatics), hexane and heptane (alkanes), n-octanol (alcohols), n-butyl acetate (esters), diisopropyl ether (ethers), and methylisobutyl ketone (ketones). The aromatic solutes included: nonpolar compounds such as benzene, toluene and naphthalene, phenolic compounds such as phenol, cresol and catechol, nitrogenous aromatics such as aniline, pyridine and aminonaphthalene, and other aromatic solutes such as naphthol, quinolinol and halogenated compounds. 100 references, 20 figures, 34 tables.

  19. Structural basis for the promiscuous biosynthetic prenylation of aromatic natural products.

    PubMed

    Kuzuyama, Tomohisa; Noel, Joseph P; Richard, Stéphane B

    2005-06-16

    The anti-oxidant naphterpin is a natural product containing a polyketide-based aromatic core with an attached 10-carbon geranyl group derived from isoprenoid (terpene) metabolism. Hybrid natural products such as naphterpin that contain 5-carbon (dimethylallyl), 10-carbon (geranyl) or 15-carbon (farnesyl) isoprenoid chains possess biological activities distinct from their non-prenylated aromatic precursors. These hybrid natural products represent new anti-microbial, anti-oxidant, anti-inflammatory, anti-viral and anti-cancer compounds. A small number of aromatic prenyltransferases (PTases) responsible for prenyl group attachment have only recently been isolated and characterized. Here we report the gene identification, biochemical characterization and high-resolution X-ray crystal structures of an architecturally novel aromatic PTase, Orf2 from Streptomyces sp. strain CL190, with substrates and substrate analogues bound. In vivo, Orf2 attaches a geranyl group to a 1,3,6,8-tetrahydroxynaphthalene-derived polyketide during naphterpin biosynthesis. In vitro, Orf2 catalyses carbon-carbon-based and carbon-oxygen-based prenylation of a diverse collection of hydroxyl-containing aromatic acceptors of synthetic, microbial and plant origin. These crystal structures, coupled with in vitro assays, provide a basis for understanding and potentially manipulating the regio-specific prenylation of aromatic small molecules using this structurally unique family of aromatic PTases.

  20. Supramolecular chemistry: from aromatic foldamers to solution-phase supramolecular organic frameworks

    PubMed Central

    2015-01-01

    Summary This mini-review covers the growth, education, career, and research activities of the author. In particular, the developments of various folded, helical and extended secondary structures from aromatic backbones driven by different noncovalent forces (including hydrogen bonding, donor–acceptor, solvophobicity, and dimerization of conjugated radical cations) and solution-phase supramolecular organic frameworks driven by hydrophobically initiated aromatic stacking in the cavity of cucurbit[8]uril (CB[8]) are highlighted. PMID:26664626

  1. Tough soluble aromatic thermoplastic copolyimides

    NASA Technical Reports Server (NTRS)

    Bryant, Robert G. (Inventor)

    2000-01-01

    Tough, soluble, aromatic, thermoplastic copolyimides were prepared by reacting 4,4'-oxydiphthalic anhydride, 3,4,3',4'-biphenyltetracarboxylic dianhydride and 3,4'-oxydianiline. Alternatively, these copolyimides may be prepared by reacting 4,4'-oxydiphthalic anhydride with 3,4,3',4'-biphenyltetracarboxylic dianhydride and 3,4'-oxydiisocyanate. Also, the copolyimide may be prepared by reacting the corresponding tetra acid and ester precursors of 4,4'-oxydiphthalic anhydride and 3,4,3',4'-biphenyltetracarboxylic dianhydride with 3,4'-oxydianiline. These copolyimides were found to be soluble in common amide solvents such as N,N'-dimethyl acetamide, N-methylpyrrolidinone, and dimethylformamide allowing them to be applied as the fully imidized copolymer and to be used to prepare a wide range of articles.

  2. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, Jr., Lawrence A.; Arganbright, Robert P.; Hearn, Dennis

    1993-01-01

    Aromatic compounds are alkylated in a combination reactor/distillation column comprising a vessel suitable for operating between 70.degree. C. and 500.degree. C. and from 0.5 to 20 atmospheres pressure; an inert distillation packing in the lower one-third of said vessel; solid acidic catalytic material such as zeolites or an acidic cation exchange resin supported in the middle one-third of said vessel; and inert distillation packing in the upper one-third of said vessel. A benzene inlet is located near the upper end of the vessel; an olefin inlet is juxtaposed with said solid acidic catalytic material; a bottoms outlet is positioned near the bottom of said vessel for removing said cumene and ethyl benzene; and an overhead outlet is placed at the top of said vessel for removing any unreacted benzene and olefin.

  3. Alkylation of organic aromatic compounds

    DOEpatents

    Smith, L.A. Jr.; Arganbright, R.P.; Hearn, D.

    1993-01-05

    Aromatic compounds are alkylated in a combination reactor/distillation column comprising a vessel suitable for operating between 70 C and 500 C and from 0.5 to 20 atmospheres pressure; an inert distillation packing in the lower one-third of said vessel; solid acidic catalytic material such as zeolites or an acidic cation exchange resin supported in the middle one-third of said vessel; and inert distillation packing in the upper one-third of said vessel. A benzene inlet is located near the upper end of the vessel; an olefin inlet is juxtaposed with said solid acidic catalytic material; a bottoms outlet is positioned near the bottom of said vessel for removing said cumene and ethyl benzene; and an overhead outlet is placed at the top of said vessel for removing any unreacted benzene and olefin.

  4. PRACTICAL SYNTHESIS OF AROMATIC DITHIOCARBAMATES

    PubMed Central

    Padungros, Panuwat; Wei, Alexander

    2015-01-01

    GRAPHICAL ABSTRACT Oxidation-sensitive N,N-diaryl dithiocarbamates (DTCs) are synthesized in good yields by the generation of metal amide salts from N-benzoyl precursors, followed by addition of CS2. para-Substituted diphenylamines are prepared by electrophilic aromatic substitution of diphenylbenzamide and saponification. Deacylation of electron-rich species such as bis(p-dimethylaminophenyl)benzamide is challenging because of the oxidative sensitivity of the anionic intermediate but could be achieved in good yield by using n-BuLi to generate a hemiaminal adduct, prior to acidification. The N,N-diaryl DTCs are stable as alkali salts and can be used to produce densely packed monolayers on gold surfaces. PMID:25999616

  5. Synthesis of perfluoroalkylene aromatic diamines

    NASA Technical Reports Server (NTRS)

    Paciorek, K. L.; Ito, T. I.; Nakahara, J. H.; Kratzer, R. H.

    1978-01-01

    Analogues of methylene dianilines were synthesized, in which the methylene group between the two aromatic nuclei was replaced by various perfluoroalkylene linkage. The hydrolytic thermal, and thermal oxidative stabilities of PMR Polyimides derived from these diamines were determined. Three types of PMR Polyimide discs were fabricated from the dimethyl ester of 3,3', 4,4'-benzophenonetetracarboxylic acid, the methyl ester of 5-norbornene-2,3-dicarboxylic acid, and one of the following three diamines: methyl dianiline, 1,3-bis(4-aminophenyl)hexafluoropropane, and 2,2-bis(4-aminophenyl)hexafluoropropane. The polyimide based on 2,2-bis(4-aminophenyl)hexafluoropropane exhibited the best hydrolytic, thermal, and thermal oxidative stability as determined by moisture uptake and thermogravimetric analysis.

  6. Fusing porphyrins with polycyclic aromatic hydrocarbons and heterocycles for optoelectronic applications

    SciTech Connect

    Thompson, Mark E.; Diev, Viacheslav; Hanson, Kenneth; Forrest, Stephen R.

    2015-08-18

    A compound that can be used as a donor material in organic photovoltaic devices comprising a non-activated porphyrin fused with one or more non-activated polycyclic aromatic rings or one or more non-activated heterocyclic rings can be obtained by a thermal fusion process. The compounds can include structures of Formula I: ##STR00001## By heating the reaction mixture of non-activated porphyrins with non-activated polycyclic aromatic rings or heterocyclic rings to a fusion temperature and holding for a predetermined time, fusion of one or more polycyclic rings or heterocyclic rings to the non-activated porphyrin core in meso,.beta. fashion is achieved resulting in hybrid structures containing a distorted porphyrin ring with annulated aromatic rings. The porphyrin core can be olygoporphyrins.

  7. Hydrotreating catalysts for diesel aromatics saturation

    SciTech Connect

    Cooper, B.H.; Stanislaus, A.; Hannerup, P.N. )

    1993-06-01

    The aromatics content of diesel feedstocks can vary widely. Straight-run stocks typically contain 20 to 40 vol% aromatics and cracked stocks 40 to 70 vol%. Thus, requirements for aromatics saturation range from moderate to severe depending on refinery location and feedstock availability. Existing middle distillate hydrotreaters designed to reduce sulfur levels can reduce aromatics content only marginally. Considerable attention has, in recent years, been paid to new catalysts and processes for aromatics saturation. The catalyst systems investigated are: (1)Conventional hydrotreating catalysts in single-stage operation; (2)Pt/alumina in two-stage operation; and (3)Sulfur-tolerant noble-metal catalyst in two-stage operation. Which of these systems should be used for a given service depends on many factors, but generally, the NiMo + NiW system is preferred at moderate levels of saturation, while for deep aromatics saturation the system using a sulfur-tolerant noble-metal catalyst is preferred. A comparison of the conditions necessary to obtain given aromatic specifications is made for all four systems. The feedstocks and their properties are summarized in a table. The paper discusses the four catalyst systems mentioned above and operating conditions.

  8. Extensive theoretical studies on two new members of the FOX-7 family: 5-(dinitromethylene)-1,4-dinitramino-tetrazole and 1,1'-dinitro-4,4'-diamino-5,5'-bitetrazole as energetic compounds.

    PubMed

    He, Piao; Zhang, Jian-Guo; Wang, Kun; Yin, Xin; Jin, Xin; Zhang, Tong-Lai

    2015-02-28

    Two novel compounds 5-(dinitromethylene)-1,4-dinitramino-tetrazole (DNAT) and 1,1'-dinitro-4,4'-diamino-5,5'-bitetrazole (DNABT) were suggested to be potential candidates of high energy density materials (HEDMs). The optimized geometry, NBO charges and electronic density, HOMO-LUMO, electrostatic potential on the surface of molecules, the IR spectrum and thermochemical parameters were calculated for inspecting the electronic structure properties at B3LYP/6-311++G** level of theory. Meanwhile, the solid states of DNAT and DNABT were studied using the crystal packing models by the plane-wave periodic local-density approximation density functional theory. Four stable polymorphous cells have been found including P212121, P21/c, P1̄ and Pbca, assigned to the orthorhombic, monoclinic and triclinic lattice systems. In addition, properties such as density, enthalpy of formation and detonation performance have also been predicted. As a result, the detonation velocity and pressure of two compounds are found to be very remarkable (DNAT: D = 9.17 km s(-1), P = 39.23 GPa; DNABT: D = 9.53 km s(-1), P = 40.92 GPa). Considering the tetrazole rings with energetic groups and the insensitive fragment of FOX-7, high positive heat of formation (583.50 kJ mol(-1) and 1081.39 kJ mol(-1)) and eminent performance render DNAT and DNABT to be very promising powerful energetically insensitive compounds. This work provides theoretical support for further experimental synthesis. PMID:25631492

  9. Interspecies metabolism of heterocyclic aromatic amines

    SciTech Connect

    Turesky, R.J.; Welti, D.H.; Fay, L.B.

    1996-12-31

    2-Amino-3,8-dimethylimadazo[4,5-f]quinoxaline (MeIQx) and other heterocyclic aromatic amines (HAAs) are rodent carcinogens and potential human carcinogens formed in cooked meats and fish. Metabolic activation of MeIQx to a genotoxin occurs through cytochrome P450 mediated N-oxidation to form N-hydroxy-MeIQx which may undergo further activation by esterification to product species which bind to DNA. Pathways of MeIQx metabolism have been elucidated in rodents and nonhuman primates to develop strategies of human biomonitoring. In addition to N-oxidation, predominant routes of detoxification include direct conjugation at the exoyclic amino group with sulfate or glucuronic acid and cytochrome P450 mediated ring oxidation. Analysis of urine from five human subjects exposed to MeIQx reveals that phase II conjugation reactions to the exocyclic amine group are prominent detoxifaction pathways while heterocyclic ring oxidation is a minor pathway. Notably, the N{sup 2-} glucuronide conjugate of N-hydroxy-MeIQx is an important metabolite in human urine. Several other metabolites have been detected in human urine which have not been previously identified in rats or nonhuman primates. Similarities and differences exist in the metabolic processing of MeIQx by humans and other species and may be a critical determinant in assessing the human health risk of HAAs.

  10. Thiol activated prodrugs of sulfur dioxide (SO2) as MRSA inhibitors.

    PubMed

    Pardeshi, Kundansingh A; Malwal, Satish R; Banerjee, Ankita; Lahiri, Surobhi; Rangarajan, Radha; Chakrapani, Harinath

    2015-07-01

    Drug resistant infections are becoming common worldwide and new strategies for drug development are necessary. Here, we report the synthesis and evaluation of 2,4-dinitrophenylsulfonamides, which are donors of sulfur dioxide (SO2), a reactive sulfur species, as methicillin-resistant Staphylococcus aureus (MRSA) inhibitors. N-(3-Methoxyphenyl)-2,4-dinitro-N-(prop-2-yn-1-yl)benzenesulfonamide (5e) was found to have excellent in vitro MRSA inhibitory potency. This compound is cell permeable and treatment of MRSA cells with 5e depleted intracellular thiols and enhanced oxidative species both results consistent with a mechanism involving thiol activation to produce SO2. PMID:25981687

  11. Hexacoordinate bonding and aromaticity in silicon phthalocyanine.

    PubMed

    Yang, Yang

    2010-12-23

    Si-E bondings in hexacoordinate silicon phthalocyanine were analyzed using bond order (BO), energy partition, atoms in molecules (AIM), electron localization function (ELF), and localized orbital locator (LOL). Bond models were proposed to explain differences between hexacoordinate and tetracoordinate Si-E bondings. Aromaticity of silicon phthalocyanine was investigated using nucleus-independent chemical shift (NICS), harmonic oscillator model of aromaticity (HOMA), conceptual density functional theory (DFT), ring critical point (RCP) descriptors, and delocalization index (DI). Structure, energy, bonding, and aromaticity of tetracoordinate silicon phthalocyanine were studied and compared with hexacoordinate one. PMID:21105726

  12. Design of aromatic-containing cell-penetrating peptide mimics with structurally modified π electronics.

    PubMed

    deRonde, Brittany M; Birke, Alexander; Tew, Gregory N

    2015-02-01

    Cell-penetrating peptides (CPPs) and their synthetic mimics (CPPMs) represent a class of molecules that facilitate the intracellular delivery of various cargo. Previous studies indicated that the presence of aromatic functionalities improved CPPM activity. Given that aromatic functionalities play prominent roles in membrane biology and participate in various π interactions, we explored whether these interactions could be optimized for improved CPPM activity. CPPMs were synthesized by ring-opening metathesis polymerization by using monomers that contained aromatic rings substituted with electron-donating and electron-withdrawing groups and covered an electrostatic potential range from -29.69 to +15.57 kcal mol(-1) . These groups altered the quadrupole moments of the aromatic systems and were used to test if such structural modifications changed CPPM activity. CPPMs were added to dye-loaded vesicles and the release of carboxyfluorescein was monitored as a function of polymer concentration. Changes in the effective polymer concentration to release 50% of the dye (effective concentration, EC50 ) were monitored. Results from this assay showed that the strength of the electron-donating and electron-withdrawing groups incorporated in the CPPMs did not alter polymer EC50 values or activity. This suggests that other design parameters may have a stronger impact on CPPM activity. In addition, these results indicate that a wide range of aromatic groups can be incorporated without negatively impacting polymer activity.

  13. Chlorinated aromatic compounds in a thermal process promoted by oxychlorination of ferric chloride.

    PubMed

    Fujimori, Takashi; Takaoka, Masaki; Morisawa, Shinsuke

    2010-03-15

    The relationship between the formation of chlorinated aromatic (aromatic-Cl) compounds and ferric chloride in the solid phase during a thermal process motivated us to study the chemical characteristics of iron in a model solid sample, a mixture of FeCl(3) x 6H(2)O, activated carbon, and boron nitride, with increasing temperature. Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy revealed drastic changes in the chemical form of amorphous iron, consistent with other analytical methods, such as X-ray diffraction using synchrotron radiation (SR-XRD) and Fourier-transform infrared (FT-IR) spectroscopy. Atomic-scale evidence of the chlorination of aromatic carbon was detected by Cl-K X-ray absorption near edge structure (XANES) spectroscopy. These results showed the thermal formation mechanism of aromatic-Cl compounds in the solid phase with ferric chloride. We attribute the formation of aromatic-Cl compounds to the chlorination of carbon, based on the oxychlorination reaction of FeCl(3) at temperatures in excess of ca. 300 degrees C, when the carbon matrix is activated by carbon gasification, catalyzed by Fe(2)O(3), and surface oxygen complexes (SOC) generated by a catalytic cycle of FeCl(2) and FeOCl. Chemical changes of trace iron in a thermal process may offer the potential to generate aromatic-Cl compounds in the solid phase.

  14. Ultimate carcinogenic metabolites from aromatic and heterocyclic aromatic amines: a computational study in relation to their mutagenic potency.

    PubMed

    Borosky, Gabriela L

    2007-02-01

    The formation of nitrenium ions from their precursors was examined by density functional theory (DFT) calculations in order to analyze the role of these electrophilic intermediates on the mutagenic activity of the parent amines. The relative reactivities for N-O bond dissociation from the N-hydroxy, N-acetoxy and N-sulfate derivatives of aniline were evaluated. Furthermore, the N-acetoxy esters from a set of 17 aromatic and heteroaromatic amines of diverse structure were considered, and correlations were sought between the calculated properties and the reported mutagenic potencies. The mutagenic activity was found to increase when a more negative charge developed at the exocyclic nitrogen of the nitrenium ion (qN) and with nitrenium ion stability. Different functional correlations were observed for the amine derivatives grouped according to their classification as aromatic (Ar), imidazo-carbocyclic (Imi-C), and imidazo-heterocyclic (Imi-H). The formation of N-acetyl nitrenium ions from aromatic amides was also considered and found to be less favorable than nitrenium ion generation from the corresponding amines. PMID:17261035

  15. Elucidating the role of aromatic interactions in rotational barriers involving aromatic systems.

    PubMed

    Lima, Carlos F R A C; Gomes, Lígia R; Low, John N; Silva, Artur M S; Santos, Luís M N B F

    2012-11-16

    The measurement of aryl-naphthyl rotational barriers, ΔG(⧧), in various solvents for two substituted 1,8-diarylnaphthalenes by dynamic (1)H NMR showed that ΔG(‡) trends in aromatic systems can be fully rationalized only when considering the different types of aromatic interactions that can be established in the ground and transition states, namely, intramolecular interactions involving the aromatic rings and specific solvation interactions. PMID:23106141

  16. Sediment-Associated Reactions of Aromatic Amines

    EPA Science Inventory

    Sorption of aromatic amines to sediments and soils can occur by both reversible physical processes and irreversible chemical processes. To elucidate the significance of these sorption pathways, the sorption kinetics of aniline and pyridine were studied in resaturated pond sedimen...

  17. The Industrial Reduction of Aromatic Nitro Compounds.

    ERIC Educational Resources Information Center

    Gilbert, G.

    1980-01-01

    Describes methods for enriching an A-level chemistry course with a series of chemical company visits. The rationale is discussed for an emphasis of the visits on the industrial reduction of aromatic nitro compounds. (CS)

  18. Sodium Perborate Oxidation of an Aromatic Amine

    ERIC Educational Resources Information Center

    Juestis, Laurence

    1977-01-01

    Describes an experiment involving the oxidation of aromatic primary amines to the corresponding azo compound; suggests procedures for studying factors that influence the yield of such a reaction, including the choice of solvent and the oxidant-amine ratio. (MLH)

  19. Aromatic-aromatic interactions enhance interfiber contacts for enzymatic formation of a spontaneously aligned supramolecular hydrogel.

    PubMed

    Zhou, Jie; Du, Xuewen; Gao, Yuan; Shi, Junfeng; Xu, Bing

    2014-02-26

    Anisotropy or alignment is a critical feature of functional soft materials in living organisms, but it remains a challenge for spontaneously generating anisotropic gel materials. Here we report a molecular design that increases intermolecular aromatic-aromatic interactions of hydrogelators during enzymatic hydrogelation for spontaneously forming an anisotropic hydrogel. This process, relying on both aromatic-aromatic interactions and enzyme catalysis, results in spontaneously aligned supramolecular nanofibers as the matrices of a monodomain hydrogel that exhibits significant birefringence. This work, as the first example of monodomain hydrogels formed via an enzymatic reaction, illustrates a new biomimetic approach for generating aligned anisotropic soft materials.

  20. Reduction of Aromatic and Heterocyclic Aromatic N-Hydroxylamines by Human Cytochrome P450 2S1

    PubMed Central

    Wang, Kai; Guengerich, F. Peter

    2013-01-01

    Many aromatic amines and heterocyclic aromatic amines (HAAs) are known carcinogens for animals and there is also strong evidence for some in human cancer. The activation of these compounds, including some arylamine drugs, involves N-hydroxylation, usually by cytochrome P450 enzymes (P450) in Family 1 (1A2, 1A1, and 1B1). We previously demonstrated that the bioactivation product of the anti-cancer agent 2-(4-amino-3-methylphenyl)-5-fluorobenzothiazole (5F 203), an N-hydroxylamine, can be reduced by P450 2S1 to its amine precursor under anaerobic conditions and, to a lesser extent, under aerobic conditions (Wang, K., and Guengerich, F. P. (2012) Chem. Res. Toxicol. 25, 1740–1751). In the present study, we tested the hypothesis that P450 2S1 is involved in the reductive biotransformation of known carcinogenic aromatic amines and HAAs. The N-hydroxylamines of 4-aminobiphenyl (4-ABP), 2-naphthylamine (2-NA), and 2-aminofluorene (2-AF) were synthesized and found to be reduced by P450 2S1 under both anaerobic and aerobic conditions. The formation of amines due to P450 2S1 reduction also occurred under aerobic conditions but was less apparent because the competitive disproportionation reactions (of the N-hydroxylamines) also yielded amines. Further, some nitroso and nitro derivatives of the arylamines could also be reduced by P450 2S1. None of the amines tested were oxidized by P450 2S1. These results suggest that P450 2S1 may be involved in the reductive detoxication of several of the activated products of carcinogenic aromatic amines and HAAs. PMID:23682735

  1. PROTONATED POLYCYCLIC AROMATIC HYDROCARBONS REVISITED

    SciTech Connect

    Ricca, Alessandra; Bauschlicher, Charles W. Jr; Allamandola, Louis J. E-mail: Charles.W.Bauschlicher@nasa.gov

    2011-02-01

    We reconsider the contribution that singly protonated polycyclic aromatic hydrocarbons (PAHs; HPAH{sup +}s) might make to the Class A component of the 6.2 {mu}m interstellar emission feature in light of the recent experimental measurements of protonated naphthalene and coronene. Our calculations on the small HPAH{sup +}s have a band near 6.2 {mu}m, as found in experiment. While the larger HPAH{sup +}s still have emission near 6.2 {mu}m, the much larger intensity of the band near 6.3 {mu}m overwhelms the weaker band at 6.2 {mu}m, so that the 6.2 {mu}m band is barely visible. Since the large PAHs are more representative of those in the interstellar medium, our work suggests that large HPAH{sup +}s cannot be major contributors to the observed emission at 6.2 {mu}m (i.e., Class A species). Saturating large PAH cations with hydrogen atoms retains the 6.2 {mu}m Class A band position, but the rest of the spectrum is inconsistent with observed spectra.

  2. Microbial Aromatization of Steroids into Equilin

    PubMed Central

    Sehgal, S. N.; Vézina, Claude

    1970-01-01

    This report describes the bioconversion of 19-hydroxy-androsta-4, 7-diene-3, 17-dione into equilin with Nocardia rubra. Through mutation and improvement of medium and of conditions, the bioconversion could be improved to yield 40% equilin for a substrate concentration of 1 g/liter. Aromatization of several other 19-hydroxy and 19-nor substrates of the androstene series is reported, and the influence of various substitutions of the substrate molecule on aromatization is discussed. PMID:5492438

  3. Carbohydrate–Aromatic Interactions in Proteins

    PubMed Central

    2015-01-01

    Protein–carbohydrate interactions play pivotal roles in health and disease. However, defining and manipulating these interactions has been hindered by an incomplete understanding of the underlying fundamental forces. To elucidate common and discriminating features in carbohydrate recognition, we have analyzed quantitatively X-ray crystal structures of proteins with noncovalently bound carbohydrates. Within the carbohydrate-binding pockets, aliphatic hydrophobic residues are disfavored, whereas aromatic side chains are enriched. The greatest preference is for tryptophan with an increased prevalence of 9-fold. Variations in the spatial orientation of amino acids around different monosaccharides indicate specific carbohydrate C–H bonds interact preferentially with aromatic residues. These preferences are consistent with the electronic properties of both the carbohydrate C–H bonds and the aromatic residues. Those carbohydrates that present patches of electropositive saccharide C–H bonds engage more often in CH−π interactions involving electron-rich aromatic partners. These electronic effects are also manifested when carbohydrate–aromatic interactions are monitored in solution: NMR analysis indicates that indole favorably binds to electron-poor C–H bonds of model carbohydrates, and a clear linear free energy relationships with substituted indoles supports the importance of complementary electronic effects in driving protein–carbohydrate interactions. Together, our data indicate that electrostatic and electronic complementarity between carbohydrates and aromatic residues play key roles in driving protein–carbohydrate complexation. Moreover, these weak noncovalent interactions influence which saccharide residues bind to proteins, and how they are positioned within carbohydrate-binding sites. PMID:26561965

  4. (Anaerobic metabolism of aromatic compounds by phototrophic bacteria: Biochemical aspects)

    SciTech Connect

    Gibson, J.

    1989-01-01

    Two aspects of the work proposed have received major emphasis during the period since the grant was activated: isolation and characterization of transposon insertion mutants of Rhodopseudomonas palusrtis defective in phototrophic growth on aromatic compounds, and attempts to purify and characterize the Coenzyme A ligase enzyme involved in activating 4-hydroxybenzoate. The HPLC apparatus was installed in August, and calibration of columns both for metabolite and for protein separations has been initiated. A start has also been made on synthesis of Coenzyme A thioesters of compounds that are potential intermediates in the anaerobic degradation pathways. 1 tab.

  5. Polynuclear aromatic hydrocarbons in the water environment*

    PubMed Central

    Andelman, Julian B.; Suess, Michael J.

    1970-01-01

    Many polynuclear aromatic hydrocarbons (PAH) are known to be carcinogenic to animals and probably to man. This review is concerned with carcinogenic and non-carcinogenic PAH in the water environment, with emphasis on 3,4-benzpyrene (BP) because it is ubiquitous, is one of the most potent of the carcinogenic PAH and has been widely studied. Although PAH are formed in combustion and other high-temperature processes, there is also evidence for their endogenous formation in plants, which may explain their ubiquity therein. Although the solubility of these compounds in pure water is very low, they may be solubilized by such materials as detergents, or they may otherwise occur in aqueous solution associated with or adsorbed on to a variety of colloidal materials or biota, and thereby be transported through the water environment. A notable characteristic of PAH is their sensitivity to light. PAH have been found in industrial and municipal waste effluents, and occur in soils, ground waters and surface waters, and their sediments and biota. With the exception of filtration or sorption by activated carbon, conventional water treatment processes do not efficiently remove them, and they have been found in domestic water supplies. Because of the ubiquity of PAH in the environment, it is impossible to prevent completely man's exposure to them; nevertheless their surveillance should be continued and their concentrations in the environment should be reduced where practicable. PMID:4100719

  6. Polynuclear aromatic hydrocarbons for fullerene synthesis in flames

    DOEpatents

    Alford, J. Michael; Diener, Michael D.

    2006-12-19

    This invention provides improved methods for combustion synthesis of carbon nanomaterials, including fullerenes, employing multiple-ring aromatic hydrocarbon fuels selected for high carbon conversion to extractable fullerenes. The multiple-ring aromatic hydrocarbon fuels include those that contain polynuclear aromatic hydrocarbons. More specifically, multiple-ring aromatic hydrocarbon fuels contain a substantial amount of indene, methylnapthalenes or mixtures thereof. Coal tar and petroleum distillate fractions provide low cost hydrocarbon fuels containing polynuclear aromatic hydrocarbons, including without limitation, indene, methylnapthalenes or mixtures thereof.

  7. Chlamydia pneumoniae encodes a functional aromatic amino acid hydroxylase.

    PubMed

    Abromaitis, Stephanie; Hefty, P Scott; Stephens, Richard S

    2009-03-01

    Chlamydia pneumoniae is a community-acquired respiratory pathogen that has been associated with the development of atherosclerosis. Analysis of the C. pneumoniae genome identified a gene (Cpn1046) homologous to eukaryotic aromatic amino acid hydroxylases (AroAA-Hs). AroAA-Hs hydroxylate phenylalanine, tyrosine, and tryptophan into tyrosine, dihydroxyphenylalanine, and 5-hydroxytryptophan, respectively. Sequence analysis of Cpn1046 demonstrated that residues essential for AroAA-H enzymatic function are conserved and that a subset of Chlamydia species contain an AroAA-H homolog. The chlamydial AroAA-Hs are transcriptionally linked to a putative bacterial membrane transport protein. We determined that recombinant Cpn1046 is able to hydroxylate phenylalanine, tyrosine, and tryptophan with roughly equivalent activity for all three substrates. Cpn1046 is expressed within 24 h of infection, allowing C. pneumoniae to hydroxylate host stores of aromatic amino acids during the period of logarithmic bacterial growth. From these results we can conclude that C. pneumoniae, as well as a subset of other Chlamydia species, encode an AroAA-H that is able to use all three aromatic amino acids as substrates. The maintenance of this gene within a number of Chlamydia suggests that the enzyme may have an important role in shaping the metabolism or overall pathogenesis of these bacteria. PMID:19141112

  8. Potent Reversible Inhibition of Myeloperoxidase by Aromatic Hydroxamates*

    PubMed Central

    Forbes, Louisa V.; Sjögren, Tove; Auchère, Françoise; Jenkins, David W.; Thong, Bob; Laughton, David; Hemsley, Paul; Pairaudeau, Garry; Turner, Rufus; Eriksson, Håkan; Unitt, John F.; Kettle, Anthony J.

    2013-01-01

    The neutrophil enzyme myeloperoxidase (MPO) promotes oxidative stress in numerous inflammatory pathologies by producing hypohalous acids. Its inadvertent activity is a prime target for pharmacological control. Previously, salicylhydroxamic acid was reported to be a weak reversible inhibitor of MPO. We aimed to identify related hydroxamates that are good inhibitors of the enzyme. We report on three hydroxamates as the first potent reversible inhibitors of MPO. The chlorination activity of purified MPO was inhibited by 50% by a 5 nm concentration of a trifluoromethyl-substituted aromatic hydroxamate, HX1. The hydroxamates were specific for MPO in neutrophils and more potent toward MPO compared with a broad range of redox enzymes and alternative targets. Surface plasmon resonance measurements showed that the strength of binding of hydroxamates to MPO correlated with the degree of enzyme inhibition. The crystal structure of MPO-HX1 revealed that the inhibitor was bound within the active site cavity above the heme and blocked the substrate channel. HX1 was a mixed-type inhibitor of the halogenation activity of MPO with respect to both hydrogen peroxide and halide. Spectral analyses demonstrated that hydroxamates can act variably as substrates for MPO and convert the enzyme to a nitrosyl ferrous intermediate. This property was unrelated to their ability to inhibit MPO. We propose that aromatic hydroxamates bind tightly to the active site of MPO and prevent it from producing hypohalous acids. This mode of reversible inhibition has potential for blocking the activity of MPO and limiting oxidative stress during inflammation. PMID:24194519

  9. The role of aromatic-aromatic interactions in strand-strand stabilization of β-sheets

    PubMed Central

    Budyak, Ivan L.; Zhuravleva, Anastasia; Gierasch, Lila M.

    2013-01-01

    Aromatic-aromatic interactions have long been believed to play key roles in protein structure, folding, and binding functions. Yet we still lack full understanding of the contributions of aromatic-aromatic interactions to protein stability and the timing of their formation during folding. Here, using as a case study an aromatic ladder in the β-barrel protein, cellular retinoic acid binding protein 1 (CRABP1), we find aromatic π stacking plays a greater role in the Phe65-Phe71 cross-strand pair while in another pair, Phe50-Phe65, hydrophobic interactions are dominant. The Phe65/Phe71 pair spans β-strands 4 and 5 in the β-barrel, which lack interstrand hydrogen bonding, and we speculate that it compensates energetically for the absence of strand-strand backbone interactions. Using perturbation analysis, we find that both aromatic-aromatic pairs form after the transition state for folding of CRABP1, thus playing a role in the final stabilization of the β-sheet rather than in its nucleation as had been earlier proposed. The aromatic interaction between strands 4–5 in CRABP1 is highly conserved in the intracellular lipid-binding protein (iLBP) family, and several lines of evidence combine to support a model wherein it acts to maintain barrel structure while allowing the dynamic opening that is necessary for ligand entry. Lastly, we carried out a bioinformatic analysis and found 51 examples of aromatic-aromatic interactions across non-hydrogen-bonded β-strands outside the iLBPs, arguing for the generality of the role played by this structural motif. PMID:23810905

  10. Synthesis of tetra- and octa-aurated heteroaryl complexes towards probing aromatic indoliums

    PubMed Central

    Yuan, Jun; Sun, Tingting; He, Xin; An, Ke; Zhu, Jun; Zhao, Liang

    2016-01-01

    Polymetalated aromatic compounds are particularly challenging synthetic goals because of the limited thermodynamic stability of polyanionic species arising from strong electrostatic repulsion between adjacent carbanionic sites. Here we describe a facile synthesis of two polyaurated complexes including a tetra-aurated indole and an octa-aurated benzodipyrrole. The imido trinuclear gold(I) moiety exhibits nucleophilicity and undergoes an intramolecular attack on a gold(I)-activated ethynyl to generate polyanionic heteroaryl species. Their computed magnetic properties reveal the aromatic character in the five-membered ring. The incorporation of the aurated substituents at the nitrogen atom can convert non-aromaticity in the parent indolium into aromaticity in the aurated one because of hyperconjugation. Thus, the concept of hyperconjugative aromaticity is extended to heterocycles with transition metal substituents. More importantly, further analysis indicates that the aurated substituents can perform better than traditional main-group substituents. This work highlights the difference in aromaticity between polymetalated aryls and their organic prototypes. PMID:27186982

  11. The potential of Cycloclasticus and Altererythrobacter strains for use in bioremediation of petroleum-aromatic-contaminated tropical marine environments.

    PubMed

    Teramoto, Maki; Suzuki, Masahito; Hatmanti, Ariani; Harayama, Shigeaki

    2010-07-01

    Cycloclasticus sp. A5, which has been suggested to be a major degrader of petroleum aromatics spilled in temperate seas, showed higher degrading activities for petroleum aromatics, at both 25 degrees C and tropical sea temperature 30 degrees C, than the novel aromatic-degrading isolates, related to Altererythrobacter epoxidivorans (97.5% similarity in the almost full-length 16S rRNA gene sequence) and Rhodovulum iodosum (96.3% similarity), obtained after enrichment on crude oil in a continuous supply of Indonesian seawater. Cycloclasticus A5 degraded petroleum aromatics at a similar rate or faster at 30 degrees C as compared to 25 degrees C, but its growth on acetate was severely inhibited at 30 degrees C. These results suggest that, although their abundance would be low in tropical seas not contaminated with aromatics, the Cycloclasticus strains could be major degraders of petroleum aromatics spilled in tropical seas. The 16S rRNA gene of the Cycloclasticus strains has been identified from Indonesian seawater, and the gene fragments showed 96.7-96.8% similarities to that of Cycloclasticus A5. Introducing Cycloclasticus A5 may be an ecologically advantageous bioremediation strategy for petroleum-aromatic-contaminated tropical seas because strain A5 would disappear at 30 degrees C after complete consumption of the aromatics. Altererythrobacter and Rhodovulum-related isolates grew well on pyruvate in 10% strength marine broth at 30 degrees C whereas Cycloclasticus A5 did not grow well on acetate in the broth at 30 degrees C. These growth results, along with its petroleum-aromatic-degrading activity, suggest that the Altererythrobacter isolate could be an important petroleum-aromatic degrader in and around nutrient-rich tropical marine environments. PMID:20541115

  12. Infrared Spectroscopy of Matrix-Isolated Polycyclic Aromatic Compounds and their Ions. 6; Polycyclic Aromatic Nitrogen Heterocycles

    NASA Technical Reports Server (NTRS)

    Mattioda, A. L.; Hudgins, Douglas M.; Bauschlicher, C. W., Jr.; Rosi, M.; Allamandola, L. J.; DeVincenzi, D. (Technical Monitor)

    2002-01-01

    The matrix-isolation technique has been employed to measure the mid-infrared spectra of several polycyclic aromatic nitrogen heterocycles in both neutral and cationic forms. The species studied include: 7,8 benzoquinoline (C13H9N); 2-azapyrene (C15H9N); 1- and 2-azabenz(a)anthracene (C17H11N); and 1-, 2-, and 4-azachrysene (also C17H11N). The experimentally measured band frequencies and intensities for each molecule are tabulated and compared with their theoretically calculated values computed using density functional theory at the B3LYP/4-31G level. The overall agreement between experiment and theory is quite good, in keeping with previous investigations involving the parent aromatic hydrocarbons. Several interesting spectroscopic trends are found to accompany nitrogen substitution into the aromatic framework of these compounds. First, for the neutral species, the nitrogen atom produces a significant increase in the total integrated infrared intensity across the 1600 - 1100/cm region and plays an essential role in the molecular vibration that underlies an uncharacteristically intense, discrete feature that is observed near 1400/cm in the spectra of 7,8 benzoquinoline, 1-azabenz(a)anthracene, and 4-azachrysene. The origin of this enhanced infrared activity and the nature of the new 1400/cm vibrational mode are explored. Finally, in contrast to the parent hydrocarbon species, these aromatic nitrogen heterocycles possess a significant permanent dipole moment. Consequently, these dipole moments and the rotational constants are reported for these species in their neutral and ionized forms.

  13. Water-soluble constituents of caraway: aromatic compound, aromatic compound glucoside and glucides.

    PubMed

    Matsumura, Tetsuko; Ishikawa, Toru; Kitajima, Junichi

    2002-10-01

    From the water-soluble portion of the methanolic extract of caraway (fruit of Carum carvi L.), an aromatic compound, an aromatic compound glucoside and a glucide were isolated together with 16 known compounds. Their structures were clarified as 2-methoxy-2-(4'-hydroxyphenyl)ethanol, junipediol A 2-O-beta-D-glucopyranoside and L-fucitol, respectively.

  14. Catalysts for polyimide foams from aromatic isocyanates and aromatic dianhydrides. [flame retardant foams

    NASA Technical Reports Server (NTRS)

    Riccitiello, S. R.; Sawko, P. M.; Estrella, C. A. (Inventor)

    1979-01-01

    Polyimide foam products having greatly improved burn-through and flame-spread resistance are prepared by the reaction of aromatic polyisocyanates with aromatic dianhydrides in the presence of metallic salts of octoic acid. The salts, for example stannous octoate, ferric octoate and aluminum octoate, favor the formation of imide linkages at the expense of other possible reactions.

  15. AROMATIC AND POLYCYCLIC AROMATIC HYDROCARBON FORMATION IN A LAMINAR PREMIXED N-BUTANE FLAME. (R825412)

    EPA Science Inventory

    Abstract

    Experimental and detailed chemical kinetic modeling work has been performed to investigate aromatic and polycyclic aromatic hydrocarbon (PAH) formation pathways in a premixed, rich, sooting, n-butane¯oxygen¯argon burner s...

  16. Aromatic metabolism of filamentous fungi in relation to the presence of aromatic compounds in plant biomass.

    PubMed

    Mäkelä, Miia R; Marinović, Mila; Nousiainen, Paula; Liwanag, April J M; Benoit, Isabelle; Sipilä, Jussi; Hatakka, Annele; de Vries, Ronald P; Hildén, Kristiina S

    2015-01-01

    The biological conversion of plant lignocellulose plays an essential role not only in carbon cycling in terrestrial ecosystems but also is an important part of the production of second generation biofuels and biochemicals. The presence of the recalcitrant aromatic polymer lignin is one of the major obstacles in the biofuel/biochemical production process and therefore microbial degradation of lignin is receiving a great deal of attention. Fungi are the main degraders of plant biomass, and in particular the basidiomycete white rot fungi are of major importance in converting plant aromatics due to their ability to degrade lignin. However, the aromatic monomers that are released from lignin and other aromatic compounds of plant biomass are toxic for most fungi already at low levels, and therefore conversion of these compounds to less toxic metabolites is essential for fungi. Although the release of aromatic compounds from plant biomass by fungi has been studied extensively, relatively little attention has been given to the metabolic pathways that convert the resulting aromatic monomers. In this review we provide an overview of the aromatic components of plant biomass, and their release and conversion by fungi. Finally, we will summarize the applications of fungal systems related to plant aromatics.

  17. Aromatic and polycyclic aromatic hydrocarbon formation in a laminar premixed n-butane flame

    SciTech Connect

    Marinov, N.M.; Pitz, W.J.; Westbrook, C.K.; Vincitore, A.M.; Castaldi, M.J.; Senkan, S.M.; Melius, C.F.

    1998-07-01

    Experimental and detailed chemical kinetic modeling work has been performed to investigate aromatic and polycyclic aromatic hydrocarbon (PAH) formation pathways in a premixed, rich, sooting, n-butane-oxygen-argon burner stabilized flame. An atmospheric pressure, laminar flat flame operated at an equivalence ratio of 2.6 was used to acquire experimental data for model validation. Gas composition analysis was conducted by an on-line gas chromatograph/mass spectrometer technique. Measurements were made in the main reaction and post-reaction zones for a number of low molecular weight species, aliphatics, aromatics, and polycyclic aromatic hydrocarbons (PAHs) ranging from two to five-fused aromatic rings. Reaction flux and sensitivity analysis were used to help identify the important reaction sequences leading to aromatic and PAH growth and destruction in the n-butane flame. Reaction flux analysis showed the propargyl recombination reaction was the dominant pathway to benzene formation. The consumption of propargyl by H atoms was shown to limit propargyl, benzene, and naphthalene formation in flames as exhibited by the large negative sensitivity coefficients. Naphthalene and phenanthrene production was shown to be plausibly formed through reactions involving resonantly stabilized cyclopentadienyl and indenyl radicals. Many of the low molecular weight aliphatics, combustion by-products, aromatics, branched aromatics, and PAHs were fairly well simulated by the model. Additional work is required to understand the formation mechanisms of phenyl acetylene, pyrene, and fluoranthene in the n-butane flame. 73 refs.

  18. An overview of the AROMAT campaigns

    NASA Astrophysics Data System (ADS)

    Merlaud, Alexis; Dekemper, Emmanuel; Van Roozendael, Michel; Constantin, Daniel; Georgescu, Lucian; Meier, Andreas; Richter, Andreas; Den Hoed, Mirjam; Allaart, Marc; Boscornea, Andreea; Vajaiac, Sorin; Bellegante, Livio; Nemuc, Anca; Nicolae, Doina; Shaifangar, Reza; Dörner, Steffen; Wagner, Thomas; Stebel, Kerstin; Schuettemeyer, Dirk

    2016-04-01

    The Airborne ROmanian Measurements of Aerosols and Trace gases (AROMAT) campaign and its follow-up AROMAT-2 were held in September 2014 and August 2015, respectively. Both campaigns focused on two geophysical targets: the city of Bucharest and the large power plants of the Jiu Valley, which are located in a rural area 170 km West of Bucharest. These two areas are complementary in terms of emitted chemical species and their spatial distributions. The objectives of the AROMAT campaigns were (i) to test recently developed airborne observation systems dedicated to air quality satellite validation studies such as the AirMAP imaging DOAS system (University of Bremen), the NO2 sonde (KNMI), and the compact SWING whiskbroom imager (BIRA), and (ii) to prepare the validation programme of the future Atmospheric Sentinels, starting with Sentinel-5 Precursor (S5P) to be launched in early summer 2016. We present results from the different airborne instrumentations and from coincident ground-based measurements (lidar, in-situ, and mobile DOAS systems) performed during both campaigns. The AROMAT dataset addresses several of the mandatory products of TROPOMI/S5P, in particular NO2 and SO2 (horizontal distribution and profile from aircraft, plume image with ground-based SO2 and NO2 cameras, transects with mobile DOAS, in-situ), H2CO (mobile MAX-DOAS), and aerosols (lidar, airborne FUBISS-ASA2 sun-photometer, and aircraft in-situ). We investigate the information content of the AROMAT dataset for satellite validation studies based on co-located OMI and GOME-2 data, and simulations of TROPOMI measurements. The experience gained during AROMAT and AROMAT-2 will be used in support of a large-scale TROPOMI/S5P validation campaign in Romania scheduled for summer 2017.

  19. Hückel's Rule of Aromaticity Categorizes Aromatic closo Boron Hydride Clusters.

    PubMed

    Poater, Jordi; Solà, Miquel; Viñas, Clara; Teixidor, Francesc

    2016-05-23

    A direct connection is established between three-dimensional aromatic closo boron hydride clusters and planar aromatic [n]annulenes for medium and large boron clusters. In particular, the results prove the existence of a link between the two-dimensional Hückel rule, as followed by aromatic [n]annulenes, and Wade-Mingos' rule of three-dimensional aromaticity, as applied to the aromatic [Bn Hn ](2-) closo boron hydride clusters. The closo boron hydride clusters can be categorized into different series, according to the n value of the Hückel (4 n+2) π rule. The distinct categories studied in this work correspond to n=1, 2, and 3. Each category increases in geometrical difficulty but, more importantly, it is possible to associate each category with the number of pentagonal layers in the structure perpendicular to the main axis. Category 1 has one pentagonal layer, category 2 has two, and category 3 has three.

  20. Delayed myelosuppression with acute exposure to hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and environmental degradation product hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) in rats

    SciTech Connect

    Jaligama, Sridhar; Kale, Vijay M.; Wilbanks, Mitchell S.; Perkins, Edward J.; Meyer, Sharon A.

    2013-02-01

    Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), a widely used munitions compound, and hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX), its N-nitroso product of anaerobic microbial nitroreduction, are contaminants of military sites. Previous studies have shown MNX to be the most acutely toxic among the nitroreduced degradation products of RDX and to cause mild anemia at high dose. The present study compares hematotoxicity with acute oral exposure to MNX with parent RDX. Both RDX and MNX caused a modest decrease in blood hemoglobin and ∼ 50% loss of granulocytes (NOAELs = 47 mg/kg) in female Sprague–Dawley rats observed 14 days post-exposure. We explored the possibility that blood cell loss observed after 14 days was delayed in onset because of toxicity to bone marrow (BM) progenitors. RDX and MNX decreased granulocyte/macrophage-colony forming cells (GM-CFCs) at 14, but not 7, days (NOAELs = 24 mg/kg). The earliest observed time at which MNX decreased GM-CFCs was 10 days post-exposure. RDX and MNX likewise decreased BM burst-forming units-erythroid (BFU-Es) at 14, but not 7, days. Granulocyte–erythrocyte–monocyte–megakaryocyte (GEMM)-CFCs were unaffected by RDX and MNX at 7 days suggesting precursor depletion did not account for GM-CFC and BFU-E loss. MNX added to the culture media was without effect on GM-CFC formation indicating no direct inhibition. Flow cytometry showed no differential loss of BM multilineage progenitors (Thy1.1{sup +}) or erythroid (CD71{sup +}) precursors with MNX suggesting myeloid and erythroid lineages were comparably affected. Collectively, these data indicate that acute exposure to both RDX and MNX caused delayed suppression of myelo- and erythropoiesis with subsequent decrease of peripheral granulocytes and erythrocytes. Highlights: ► Acute oral exposure to munitions RDX causes myelosuppression. ► Environmental degradation product MNX is comparable in effect. ► RDX and MNX are cytotoxic to both myeloid and erythroid

  1. Structures of human transthyretin complexed with thyroxine at 2.0 A resolution and 3',5'-dinitro-N-acetyl-L-thyronine at 2.2 A resolution.

    PubMed

    Wojtczak, A; Cody, V; Luft, J R; Pangborn, W

    1996-07-01

    The molecular structures of two human transthyretin (hTTR, prealbumin) complexes, co-crystallized with thyroxine (3,5,3',5'-tetraiodo-L-thyronine; T(4)), and with 3',5'-dinitro-N-acetyl-LL-thyronine (DNNAT), were determined by X-ray diffraction methods. Crystals of both structures are orthorhombic, space group P2(1)2(1)2, and have two independent monomers in the asymmetric unit of the crystal lattice. These structures have been refined to 17.0% for 8-2.0 A resolution data for the T(4) complex (I), and to R = 18.4% for 8-2.2 A resolution data for the DNNAT structure (II). This report provides a detailed description of T(4) binding to wild-type hTTR at 2.0 A resolution, as well as DNNAT. In both structures, the two independent hormone-binding sites of the TTR tetramer are occupied by ligand. A 50% statistical disorder model was applied to account for the crystallographic twofold symmetry along the binding channel and the lack of such symmetry for the ligands. Results for the co-crystallized T(4) complex show that T(4) binds deep in the hormone-binding channel and displaces the bound water previously reported for T(4) soaked into a native transthyretin crystal [Blake & Oatley (1977). Nature (London), 268, 115-120]. DNNAT also binds deeper in the channel toward the tetramer center than T(4) with the nitro groups occupying the symmetrical innermost halogen pockets. The N-acetyl moiety does not form polar contacts with the protein side chains as it is oriented toward the center of the channel. The weak binding affinity of DNNAT results from the loss of hydrophobic interactions with the halogen binding pockets as observed in T(4) binding. These data suggest that the halogen-binding sites toward the tetramer center are of primary importance as they are occupied by analogues with weak affinity to TTR, and are therefore selected over the other halogen sites which contribute more strongly to the overall binding affinity.

  2. Soot formation during pyrolysis of aromatic hydrocarbons

    SciTech Connect

    Clary, D.W.

    1985-01-01

    A study combining experimental, empirical modeling, and detailed modeling techniques has been conducted to develop a better understanding of the chemical reactions involved in soot formation during the high-temperature pyrolysis of aromatic and other unsaturated hydrocarbons. The experiments were performed behind reflected shock waves in a conventional shock-tube with soot formation monitored via attenuation of a laser beam at 633 nm. Soot-formation measurements were conducted with toluene-argon and benzene-argon mixtures. Detailed kinetic models of soot formation were developed for pyrolyzing acetylene, butadiene, ethylene and benzene. The computational results indicate the importance of compact, fused polycyclic aromatic hydrocarbons as soot intermediates and the importance of the reactivation of these intermediates by hydrogen atoms to form aromatic radicals. The overshoot by hydrogen atoms of their equilibrium concentration provides a driving kinetic force for soot formation. The results with ethylene and butadiene indicate that acetylene is an important growth species for soot formation for these fuels. The benzene model suggests that reactions between aromatic species may be important for soot formation from aromatic fuels.

  3. Interplay between aromaticity and strain in double group transfer reactions to 1,2-benzyne.

    PubMed

    Fernández, Israel; Cossío, Fernando P

    2016-05-30

    Density Functional Theory calculations are used to explore the double hydrogen atom transfer from different alkanes to 1,2-benzyne. State-of-the-art calculations including the Activation Strain Model of reactivity, Energy Decomposition Analysis, and Valence Bond methods, reveal the origins of the relatively low activation barriers computed for these processes compared to the analogous reaction involving acetylene. In addition, the interplay between the in-plane aromaticity of the corresponding transition states and the variation of the π-aromaticity associated with the benzyne moiety as well as their influence on the barrier heights of the transformations are analyzed in detail.

  4. Prediction of aromatic amine carcinogenicity: QSAR base on calculated delocalizibility of hypothetical nitrenium ion intermediate

    SciTech Connect

    Purdy, R.

    1995-12-31

    Predictors for the reactivity of primary aromatic amines were hypothesized and tested on a small set of amines. It was found that the delocalizibility on the nitrogen of the previously hypothesized nitrenium ion intermediate was the only good predictor. The strength of this predictor was tested on a larger set of amines and a cut off value for discriminating between carcinogens and noncarcinogens was chosen. This QSAR supports the hypothesis that a nitrenium ion is an intermediate in the activation of primary aromatic amines to active carcinogens.

  5. Chemotaxis of Azospirillum species to aromatic compounds

    SciTech Connect

    Lopez-de-Victoria, G.; Lovell, C.R. )

    1993-09-01

    Azospirillum sspeciesare free-living nitrogen fixing bacteria commonly found in soils and in association with plant roots, including important agricultural crops. Rhizosphere colonization my Azospirillum species has been shown to stimulate growth of a variety of plant species. Chemotaxis is one of the properties which may contribute to survival, rhizosphere colonization and the initiation of mutualistic interactions by Azospirillum species. This study evaluates the chemotactic responses of three Azospirillum stains to a variety of aromatic compounds:benzoate, catechol, 4-HB, and PCA. Results indicate that the same aromatic substance can elicit different chemotactic responses from different Azospirillum species, and that Azospirillum can detect aromatic substrates at concentrations similar to those they encounter naturally. 36 refs., 1 fig., 6 tabs.

  6. Thermochemical factors affecting the dehalogenation of aromatics.

    PubMed

    Sadowsky, Daniel; McNeill, Kristopher; Cramer, Christopher J

    2013-12-17

    Halogenated aromatics are one of the largest chemical classes of environmental contaminants, and dehalogenation remains one of the most important processes by which these compounds are degraded and detoxified. The thermodynamic constraints of aromatic dehalogenation reactions are thus important for understanding the feasibility of such reactions and the redox conditions necessary for promoting them. Accordingly, the thermochemical properties of the (poly)fluoro-, (poly)chloro-, and (poly)bromobenzenes, including standard enthalpies of formation, bond dissociation enthalpies, free energies of reaction, and the redox potentials of Ar-X/Ar-H couples, were investigated using a validated density functional protocol combined with continuum solvation calculations when appropriate. The results highlight the fact that fluorinated aromatics stand distinct from their chloro- and bromo- counterparts in terms of both their relative thermodynamic stability toward dehalogenation and how different substitution patterns give rise to relevant properties, such as bond strengths and reduction potentials.

  7. Bacterial strategies for growth on aromatic compounds.

    PubMed

    George, Kevin W; Hay, Anthony G

    2011-01-01

    Although the biodegradation of aromatic compounds has been studied for over 40 years, there is still much to learn about the strategies bacteria employ for growth on novel substrates. Elucidation of these strategies is crucial for predicting the environmental fate of aromatic pollutants and will provide a framework for the development of engineered bacteria and degradation pathways. In this chapter, we provide an overview of studies that have advanced our knowledge of bacterial adaptation to aromatic compounds. We have divided these strategies into three broad categories: (1) recruitment of catabolic genes, (2) expression of "repair" or detoxification proteins, and (3) direct alteration of enzymatic properties. Specific examples from the literature are discussed, with an eye toward the molecular mechanisms that underlie each strategy.

  8. The fundamental chemical equation of aromaticity.

    PubMed

    Chauvin, Remi; Lepetit, Christine

    2013-03-21

    In the search for the chemical measure of molecular aromaticity, namely the energetic gain of a cyclic delocalized structure for just being cyclic, the numerous definitions of generic aromatic stabilisation energies proposed hitherto stand as approximates of the conceptual limit devised within the framework of spectral graph theory, i.e. the topological resonance energy (TRE). After a 36 year challenge, the TRE acyclic reference of any π-cyclic molecule, originally merely defined by an abstract matching polynomial, is now given a real chemical structure: the Möbius-twisted head-to-tail metathesis cyclo-dimer of the parent ring. The original treatment at the Hückel molecular orbital level of theory can now be extended to DFT or ab initio levels. The corresponding ring opening-closing-twisting chemical transformation provides the observable basis for the measure of aromaticity under either vertical or adiabatic conditions.

  9. Ion exclusion chromatography of aromatic acids.

    PubMed

    Mansour, Fotouh R; Kirkpatrick, Christine L; Danielson, Neil D

    2013-08-01

    The determination of aromatic acids by ion exclusion chromatography is challenging due to peak tailing and the long retention time of hydrophobic solutes. This review discusses the retention mechanisms and the factors affecting retention, eluents and detection methods used in ion exclusion chromatography of aromatic acids such as mono-, di-, tri- and tetra-carboxylic acids, amino acids, sulfonates and phenol. In addition, the different approaches used to improve the chromatographic separation of these compounds are also discussed. These approaches include introducing an internal gradient of the ionic strength, using vacancy ion exclusion chromatography, employing a hydrophilic cation exchange resin or adding a modifier such as heptanol to the dilute sulfuric acid mobile phase. The applications of these methods in the analysis of aromatic acids are provided with a table summarizing the stationary phases, the mobile phases and the detection methods.

  10. Highly Dispersed Pt Nanoparticles for the Production of Aromatic Hydrocarbons by the Catalytic Degrading of Alkali Lignin.

    PubMed

    Sanyoto, Bernardi; Dwiatmoko, Adid Adep; Choi, Jae-Wook; Ha, Jeong-Myeong; Suh, Dong Jin; Kim, Chang Soo; Lim, Jong-Choo

    2016-05-01

    Aromatic hydrocarbons were produced from lignin, a complex natural amorphous polymer commonly regarded as by-product of the pulping process and from biofuel production. The catalytic decomposition of lignin using supported Pt catalysts was performed to produce small molecule hydrocarbons. Aromatic small-molecule hydrocarbon products were identified and quantified using GC/MS and GC-FID, which demonstrated that 27.6% of aromatic hydrocarbons were obtained from the activated carbon-supported Pt (Pt/AC) catalyst which had the highest Pt surface area. PMID:27483791

  11. Recent advances in the ruthenium-catalyzed hydroarylation of alkynes with aromatics: synthesis of trisubstituted alkenes.

    PubMed

    Manikandan, Rajendran; Jeganmohan, Masilamani

    2015-11-14

    The hydroarylation of alkynes with substituted aromatics in the presence of a metal catalyst via chelation-assisted C-H bond activation is a powerful method to synthesize trisubstituted alkenes. Chelation-assisted C-H bond activation can be done by two ways: (a) an oxidative addition pathway and (b) a deprotonation pathway. Generally, a mixture of cis and trans stereoisomeric as well as regioisomeric trisubstituted alkenes was observed in an oxidative addition pathway. In the deprotonation pathway, the hydroarylation reaction can be done in a highly regio- and stereoselective manner, and enables preparation of the expected trisubstituted alkenes in a highly selective manner. Generally, ruthenium, rhodium and cobalt complexes are used as catalysts in the reaction. In this review, a ruthenium-catalyzed hydroarylation of alkynes with substituted aromatics is covered completely. The hydroarylation reaction of alkynes with amide, azole, carbamate, phosphine oxide, amine, acetyl, sulfoxide and sulphur directed aromatics is discussed.

  12. QSAR and SAR studies on the reduction of some aromatic nitro compounds by xanthine oxidase.

    PubMed

    Thakur, Mamta; Thakur, Abhilash; Balasubramanian, Krishnan

    2006-01-01

    This work describes QSAR and SAR studies on the reduction of 27 aromatic nitro compounds by xanthine oxidase using both distance-based topological indices and quantum molecular descriptors along with indicator parameters. The application of a multiple linear regression analysis indicated that a combination of distance-based topological indices with the ad hoc molecular descriptors and the indicator parameters yielded a statistically significant model for the activity, log K (the reduction of aromatic nitro compounds by xanthine oxidase). The final selection of a potential aromatic nitro compound for the reduction by xanthine oxidase is made by quantum molecular modeling. We have found that, among the various parameters, the quantum Mulliken charge parameters on the fourth atom or para position relative to the nitro group correlated best with the activity.

  13. Experimental and modeling investigation of aromatic and polycyclic aromatic hydrocarbon formation in a premixed ethylene flame

    SciTech Connect

    Castaldi, M.J.; Marinov, N.M.; Melius, C.F.

    1996-02-01

    Experimental and detailed chemical kinetic modeling has been performed to investigate aromatic and polyaromatic hydrocarbon formation pathways in a rich, sooting, ethylene-oxygen-argon premixed flame. An atmospheric pressure, laminar flat flame operated at an equivalence ratio of 2.5 was used to acquire experimental data for model validation. Gas composition analysis was conducted by an on-line gas chromatograph/mass spectrometer (GC/MS) technique. Measurements were made in the flame and post-flame zone for a number of low molecular weight species, aliphatics, aromatics and polycyclic aromatic hydrocarbons (PAHs) ranging from two to five-aromatic fused rings. The modeling results show the key reaction sequences leading to aromatic and polycyclic aromatic hydrocarbon growth involve the combination of resonantly stabilized radicals. In particular, propargyl and 1-methylallenyl combination reactions lead to benzene and methyl substituted benzene formation, while polycyclic aromatics are formed from cyclopentadienyl radicals and fused rings that have a shared C{sub 5} side structure. Naphthalene production through the reaction step of cyclopentadienyl self-combination and phenanthrene formation from indenyl and cyclopentadienyl combination were shown to be important in the flame modeling study. The removal of phenyl by O{sub 2} leading to cyclopentadienyl formation is expected to play a pivotal role in the PAH or soot precursor growth process under fuel-rich oxidation conditions.

  14. AN AROMATIC INVENTORY OF THE LOCAL VOLUME

    SciTech Connect

    Marble, A. R.; Engelbracht, C. W.; Block, M.; Van Zee, L.; Dale, D. A.; Cohen, S. A.; Schuster, M. D.; Smith, J. D. T.; Gordon, K. D.; Wu, Y.; Lee, J. C.; Kennicutt, R. C.; Skillman, E. D.; Johnson, L. C.; Calzetti, D.; Lee, H.

    2010-05-20

    Using infrared photometry from the Spitzer Space Telescope, we perform the first inventory of aromatic feature emission (also commonly referred to as polycyclic aromatic hydrocarbon emission) for a statistically complete sample of star-forming galaxies in the local volume. The photometric methodology involved is calibrated and demonstrated to recover the aromatic fraction of the Infrared Array Camera 8 {mu}m flux with a standard deviation of 6% for a training set of 40 SINGS galaxies (ranging from stellar to dust dominated) with both suitable mid-infrared Spitzer Infrared Spectrograph spectra and equivalent photometry. A potential factor of 2 improvement could be realized with suitable 5.5 {mu}m and 10 {mu}m photometry, such as what may be provided in the future by the James Webb Space Telescope. The resulting technique is then applied to mid-infrared photometry for the 258 galaxies from the Local Volume Legacy (LVL) survey, a large sample dominated in number by low-luminosity dwarf galaxies for which obtaining comparable mid-infrared spectroscopy is not feasible. We find the total LVL luminosity due to five strong aromatic features in the 8 {mu}m complex to be 2.47 x 10{sup 10} L{sub sun} with a mean volume density of 8.8 x 10{sup 6} L{sub sun} Mpc{sup -3}. Twenty-four of the LVL galaxies, corresponding to a luminosity cut at M{sub B} = -18.22, account for 90% of the aromatic luminosity. Using oxygen abundances compiled from the literature for 129 of the 258 LVL galaxies, we find a correlation between metallicity and the aromatic-to-total infrared emission ratio but not the aromatic-to-total 8 {mu}m dust emission ratio. A possible explanation is that metallicity plays a role in the abundance of aromatic molecules relative to the total dust content, but other factors, such as star formation and/or the local radiation field, affect the excitation of those molecules.

  15. Production of aromatics from di- and polyoxygenates

    DOEpatents

    Beck, Taylor; Blank, Brian; Jones, Casey; Woods, Elizabeth; Cortright, Randy

    2016-08-02

    Methods, catalysts, and reactor systems for producing in high yield aromatic chemicals and liquid fuels from a mixture of oxygenates comprising di- and polyoxygenates are disclosed. Also disclosed are methods, catalysts, and reactor systems for producing aromatic chemicals and liquid fuels from oxygenated hydrocarbons such as carbohydrates, sugars, sugar alcohols, sugar degradation products, and the like; and methods, catalysts, and reactor systems for producing the mixture of oxygenates from oxygenated hydrocarbons such as carbohydrates, sugars, sugar alcohols, sugar degradation products, and the like. The disclosed catalysts for preparing the mixture of oxygenates comprise a Ni.sub.nSn.sub.m alloy and a crystalline alumina support.

  16. Production of aromatics from di- and polyoxygenates

    DOEpatents

    Beck, Taylor; Blank, Brian; Jones, Casey; Woods, Elizabeth; Cortright, Randy

    2016-09-13

    Methods, catalysts, and reactor systems for producing in high yield aromatic chemicals and liquid fuels from a mixture of oxygenates comprising di- and polyoxygenates are disclosed. Also disclosed are methods, catalysts, and reactor systems for producing aromatic chemicals and liquid fuels from oxygenated hydrocarbons such as carbohydrates, sugars, sugar alcohols, sugar degradation products, and the like; and methods, catalysts, and reactor systems for producing the mixture of oxygenates from oxygenated hydrocarbons such as carbohydrates, sugars, sugar alcohols, sugar degradation products, and the like. The disclosed catalysts for preparing the mixture of oxygenates comprise a Group VIII metal and a crystalline alumina support.

  17. Aromatic sulfide/sulfone polymer production

    SciTech Connect

    Scoggins, L.E.; Hoover, K.C.; Shang, W.W.

    1991-05-14

    This patent describes a process for the production of aromatic sulfide/sulfone polymer. It comprises: contacting at least one lactam, at least one alkali metal hydrosulfide, water, and at least one base selected from the group consisting of alkali metal hydroxides and mixtures of alkali metal hydroxides with alkali metal carbonates under reaction conditions of time and temperature sufficient to produce a mixture containing a complex which comprises the at least one alkali metal hydrosulfide and contacting the mixture produced with a least one dihaloaromatic sulfone under polymerization conditions for a period of time sufficient to form an aromatic sulfide/sulfone polymer.

  18. Valorization of essential oils from Moroccan aromatic plants.

    PubMed

    Santana, Omar; Fe Andrés, Maria; Sanz, Jesús; Errahmani, Naima; Abdeslam, Lamiri; González-Coloma, Azucena

    2014-08-01

    The chemical composition and biological activity of cultivated and wild medicinal and aromatic plants from Morocco (Artemisia herba-alba, Lippia citriodora, Mentha pulegium, M. spicata, Myrtus communis, Rosmarinus officinalis, and Thymus satureioides) are described. The essential oils (EOs) of these species have been analyzed by GC-MS. The antifeedant, nematicidal and phytotoxic activities of the EOs were tested on insect pests (Spodoptera littoralis, Myzus persicae and Rhopalosiphum padi), root-knot nematodes (Meloydogine javanica) and plants (Lactuca sativa, Lolium perenne and Lycopersicum esculentum). EOs from A. herba-alba, M. pulegium and R. officinalis were strong antifeedants against S. littoralis, M. persicae and R. padi. EOs from L. citriodora, M. spicata and T. satureioides showed high nematicidal activity. These biological effects are explained by the activity of the major EO components and/or synergistic effects. PMID:25233584

  19. Molecular dosimetry of aromatic amines in human populations

    SciTech Connect

    Skipper, P.L.; Tannenbaum, S.R.

    1994-10-01

    Certain aromatic amines carcinogenic for the human urinary bladder, such as 4-aminobiphenyl, undergo hepatic metabolic activation to N-hydroxylamines, which are transported to the bladder. During the transport process, these reactive species come in contact with hemoglobin and react with this blood protein. The principal hemoglobin adduct formed is a cysteine sulfinamide, and quantitative methods have been developed for the analysis of sulfinamide adducts at the levels present in ordinary human blood specimens. N-acetylation is an alternative metabolic fate to N-hydroxylation. The amount of hemoglobin adduct is decreased to the extent that this pathway is increased relative to N-hydroxylation. Thus, the hemoglobin adduct is sensitive to dose, cytochrome P-450-mediated activation, and N-acetyltransferase-mediated detoxification. In addition, it has been shown that DNA adduct concentration of 4-aminobiphenyl present in human bladder epithelial cells is significantly associated with hemoglobin adduct levels. Thus, the hemoglobin adduct of 4-aminobiphenyl, and perhaps several other aromatic amines, is a good dosimeter for the target tissue dose of the ultimate carcinogenic metabolite of these amines. Several studies have been undertaken in which the hemoglobin adducts of aminobiphenyls in human blood specimens were determined quantitatively. Information concerning exposure status and acetylator phenotype of the same individuals was obtained simultaneously. The results of these studies indicate that the hemoglobin adduct of 4-aminobiphenyl is closely associated with three major risk factors for bladder cancer; cigarette smoking, type of tobacco smoked, and acetylator phenotype. They also support a major etiologic role for aromatic amines in much of human bladder cancer. 42 refs., 4 figs., 1 tab.

  20. Fluorescence method for enzyme analysis which couples aromatic amines with aromatic aldehydes

    DOEpatents

    Smith, Robert E. [557 Escondido Cir., Livermore, CA 94550; Dolbeare, Frank A. [5178 Diane La., Livermore, CA 94550

    1980-10-21

    Analysis of proteinases is accomplished using conventional amino acid containing aromatic amine substrates. Aromatic amines such as 4-methoxy-2-naphthylamine (4M2NA), 2-naphthylamine, aminoisophthalic acid dimethyl ester, p-nitroaniline, 4-methoxy-1-aminofluorene and coumarin derivatives resulting from enzymatic hydrolysis of the substrate couples with aromatic aldehydes such as 5-nitrosalicylaldehyde (5-NSA), benzaldehyde and p-nitrobenzaldehyde to produce Schiff-base complexes which are water insoluble. Certain Schiff-base complexes produce a shift from blue to orange-red (visible) fluorescence. Such complexes are useful in the assay of enzymes.

  1. Fluorescence method for enzyme analysis which couples aromatic amines with aromatic aldehydes

    DOEpatents

    Smith, R.E.; Dolbeare, F.A.

    1980-10-21

    Analysis of proteinases is accomplished using conventional amino acid containing aromatic amine substrates. Aromatic amines such as 4-methoxy-2-naphthylamine (4M2NA), 2-naphthylamine, aminoisophthalic acid dimethyl ester, p-nitroaniline, 4-methoxy-1-aminofluorene and coumarin derivatives resulting from enzymatic hydrolysis of the substrate couples with aromatic aldehydes such as 5-nitrosalicylaldehyde (5-NSA), benzaldehyde and p-nitrobenzaldehyde to produce Schiff-base complexes which are water insoluble. Certain Schiff-base complexes produce a shift from blue to orange-red (visible) fluorescence. Such complexes are useful in the assay of enzymes. No Drawings

  2. Fluorescence method for enzyme analysis which couples aromatic amines with aromatic aldehydes

    DOEpatents

    Smith, Robert E.; Dolbeare, Frank A.

    1979-01-01

    Analysis of proteinases is accomplished using conventional amino acid containing aromatic amine substrates. Aromatic amines such as 4-methoxy-2-naphthylamine (4M2NA), 2-naphthylamine, aminoisophthalic acid dimethyl ester, p-nitroaniline, 5-methoxy-1-aminofluorene and coumarin derivatives resulting from enzymatic hydrolysis of the substrate couples with aromatic aldehydes such as 5-nitrosalicylaldehyde (5-NSA), benzaldehyde and p-nitrobenzaldehyde to produce Schiff-base complexes which are water insoluble. Certain Schiff-base complexes produce a shift from blue to orange-red (visible) fluorescence. Such complexes are useful in the assay of enzymes.

  3. Regulation of aromatics biodegradation by rhl quorum sensing system through induction of catechol meta-cleavage pathway.

    PubMed

    Yong, Yang-Chun; Zhong, Jian-Jiang

    2013-05-01

    The mechanism for quorum sensing (QS) regulation on aromatics degradation was investigated. Deletion of rhl QS system resulted in a significant decrease in aromatics biodegradation as well as the activity of catechol 2,3-dioxygenase (C23O, key enzyme for catechol meta-cleavage pathway) in Pseudomonas aeruginosa CGMCC1.860. Interestingly, this repression could be relieved by N-butyryl homoserine lactone (the signaling molecule of rhl QS system) addition. In accordance, the transcription level of nahH (the gene encoding C23O) and nahR (transcriptional activator) also responded to rhl perturbation in a similar way. The results indicated that rhl QS system positively controlled the catechol meta-cleavage pathway, and hence improved aromatics biodegradation. It suggested manipulation of QS system could be a promising strategy to tune the catechol cleavage pathway and to control aromatics biodegradation.

  4. Fluorescent aromatic sensors and their methods of use

    NASA Technical Reports Server (NTRS)

    Meador, Michael A. (Inventor); Tyson, Daniel S. (Inventor); Ilan, Ulvi F. (Inventor)

    2012-01-01

    Aromatic molecules that can be used as sensors are described. The aromatic sensors include a polycyclic aromatic hydrocarbon core with a five-membered imide rings fused to the core and at least two pendant aryl groups. The aromatic sensor molecules can detect target analytes or molecular strain as a result of changes in their fluorescence, in many cases with on-off behavior. Aromatic molecules that fluoresce at various frequencies can be prepared by altering the structure of the aromatic core or the substituents attached to it. The aromatic molecules can be used as sensors for various applications such as, for example, the detection of dangerous chemicals, biomedical diagnosis, and the detection of damage or strain in composite materials. Methods of preparing aromatic sensor molecules are also described.

  5. SEDIMENT-ASSOCIATED REACTIONS OF AROMATIC AMINES. 2. QSAR DEVELOPMENT

    EPA Science Inventory

    The fate of aromatic amines in soils and sediments is dominated by irreversible binding through nucleophilic addition and oxidative radical coupling. Despite the common occurrence of the aromatic amine functional group in organic chemicals, the molecular properties useful for pr...

  6. Anaerobic degradation of homocyclic aromatic compounds via arylcarboxyl-coenzyme A esters: organisms, strategies and key enzymes.

    PubMed

    Boll, Matthias; Löffler, Claudia; Morris, Brandon E L; Kung, Johannes W

    2014-03-01

    Next to carbohydrates, aromatic compounds are the second most abundant class of natural organic molecules in living organic matter but also make up a significant proportion of fossil carbon sources. Only microorganisms are capable of fully mineralizing aromatic compounds. While aerobic microbes use well-studied oxygenases for the activation and cleavage of aromatic rings, anaerobic bacteria follow completely different strategies to initiate catabolism. The key enzymes related to aromatic compound degradation in anaerobic bacteria are comprised of metal- and/or flavin-containing cofactors, of which many use unprecedented radical mechanisms for C-H bond cleavage or dearomatization. Over the past decade, the increasing number of completed genomes has helped to reveal a large variety of anaerobic degradation pathways in Proteobacteria, Gram-positive microbes and in one archaeon. This review aims to update our understanding of the occurrence of aromatic degradation capabilities in anaerobic microorganisms and serves to highlight characteristic enzymatic reactions involved in (i) the anoxic oxidation of alkyl side chains attached to aromatic rings, (ii) the carboxylation of aromatic rings and (iii) the reductive dearomatization of central arylcarboxyl-coenzyme A intermediates. Depending on the redox potential of the electron acceptors used and the metabolic efficiency of the cell, different strategies may be employed for identical overall reactions.

  7. Forty years of Clar's aromatic π-sextet rule.

    PubMed

    Solà, Miquel

    2013-01-01

    In 1972 Erich Clar formulated his aromatic π-sextet rule that allows discussing qualitatively the aromatic character of benzenoid species. Now, 40 years later, Clar's aromatic π-sextet rule is still a source of inspiration for many chemists. This simple rule has been validated both experimentally and theoretically. In this review, we select some particular examples to highlight the achievement of Clar's aromatic π-sextet rule in many situations and we discuss two recent successful cases of its application.

  8. Aerobic palladium(II)-catalyzed dehydrogenation of cyclohexene-1-carbonyl indole amides: an indole-directed aromatization.

    PubMed

    Kandukuri, Sandeep R; Oestreich, Martin

    2012-10-01

    A palladium(II)-catalyzed oxidative dehydrogenation of cyclohexene-1-carbonyl indole amides yielding the corresponding benzoylindoles is reported. The new aromatization is also applied to functionalized indoles such as tryptamine and tryptophan. The tethered indole is likely acting as a directing group for allylic C-H bond activation, and there is evidence for a mechanism proceeding through 1,3-diene formation followed by aromatization. PMID:22950832

  9. On the aromatic stabilization of benzenoid hydrocarbons.

    PubMed

    Ciesielski, Arkadiusz; Stepień, Dorota K; Dobrowolski, Michał A; Dobrzycki, Łukasz; Cyrański, Michał K

    2012-10-18

    A general scheme for estimation of aromatic stabilization energies of benzenoid hydrocarbons based on selected topological features has been presented. The reactions have been applied to benzene, naphthalene, anthracene, phenanthrene, pyrene, tetracene, benz[a]anthracene, chrysene, [4]-helicene, anthanthrene and coronene.

  10. RECOVERY OF URANIUM BY AROMATIC DITHIOCARBAMATE COMPLEXING

    DOEpatents

    Neville, O.K.

    1959-08-11

    A selective complexing organic solvent extraction process is presented for the separation of uranium values from an aqueous nitric acid solution of neutron irradiated thorium. The process comprises contacting the solution with an organic aromatic dithiccarbamaie and recovering the resulting urancdithiccarbamate complex with an organic solvent such as ethyl acetate.

  11. Effect of fuel aromaticity on diesel emissions

    SciTech Connect

    Barbella, R.; Ciajolo, A.; D'Anna, A. ); Bertoli, C. )

    1989-09-01

    The effect of the fuel aromatic content on soot and heavy hydrocarbon emissions from a single-cylinder direct-injection diesel engine has been investigated burning a pure paraffinic fuel (n-tetradecane), a tetradecane-toluene mixture (70-30 vol%) and two diesel oils with different aromatic content. All experiments were at various air-fuel ratios with constant engine speed and injection timing advance. The detailed chemical analysis of exhaust heavy hydrocarbons in terms of mass percentage of paraffins, monoaromatics, polyaromatics and polar compounds, and the gas chromatography-mass spectrometry of each hydrocarbon class have been compared with the original fuel analyses in order to discriminate the unburned fuel compounds from the combustion-formed products. The soot emission rate has been found to be independent of the fuel aromatic content, but the fuel affects the quality and quantity of heavy hydrocarbon emission. Low amounts of heavy hydrocarbons, mainly partially oxidized compounds, are emitted from tetradecane combustion, whereas diesel fuel oils produced high emissions of heavy hydrocarbons, mainly unburned fuel compounds. The emission of polynuclear aromatic hydrocarbons (PAH) from tetradecane and tetradecane-toluene diesel combustion indicates that these compounds are combustion-formed products, but unburned fuel PAH are the main components of PAH emitted by the diesel fuel oils.

  12. Thermoset/Thermoplastic Aromatic Polyamides for Composites

    NASA Technical Reports Server (NTRS)

    St. Clair, T. L.; St. Clair, A. K.; Barrick, J. D.; Wolfe, J. F.; Greenwood, T. D.

    1983-01-01

    Aromatic polyamides are processed at relatively low temperature, then heat-treated to attain high softening temperature required when polyamides are used as matrix resins in structural composites. New polyamides are compatable with organic fibers often used as reinforcing agents in such composites Pendent propargyl groups serve as latent cross-linking agents in new series of polyamide resins.

  13. Reaction of disubstituted aromatic compounds with styrene

    SciTech Connect

    Grushin, A.I.; Grigor'ev, V.V.; Prokof'ev, K.V.; Kozlova, N.M.

    1988-03-20

    Hydrocarbons of the 1,1-diphenylethane type were obtained by the reaction of styrene with various disubstituted derivatives of benzene in the presence of titanium tetrachloride. It was found that the yield of the desired compound depends on the strength of the electron-donating substituents and on steric factors in the aromatic ring.

  14. An electronic aromaticity index for large rings.

    PubMed

    Matito, Eduard

    2016-04-28

    We introduce a new electronic aromaticity index, AV1245, consisting of an average of the 4-center multicenter indices (MCI) along the ring that keeps a positional relationship of 1, 2, 4, 5. AV1245 measures the extent of transferability of the delocalized electrons between bonds 1-2 and 4-5, which is expected to be large in conjugated circuits and, therefore, in aromatic molecules. A new algorithm for the calculation of MCI for large rings is also introduced and used to produce the data for the calibration of the new aromaticity index. AV1245 does not rely on reference values, does not suffer from large numerical precision errors, and it does not present any limitation on the nature of atoms, the molecular geometry or the level of calculation. It is a size-extensive measure with low computational cost that grows linearly with the number of ring members. Therefore, it is especially suitable to study the aromaticity of large molecular rings such as those occurring in belt-shaped Möbius structures or porphyrins. The analysis of AV1245 in free-base and bis-metalated Pd [32]octaphyrins(1,0,1,0,1,0,1,0) completes this study. PMID:26878146

  15. 40 CFR 721.10258 - Aromatic hydrocarbon (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Aromatic hydrocarbon (generic). 721... Substances § 721.10258 Aromatic hydrocarbon (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as aromatic hydrocarbon (PMN...

  16. 40 CFR 721.10259 - Halogenated aromatic hydrocarbon (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Halogenated aromatic hydrocarbon... Specific Chemical Substances § 721.10259 Halogenated aromatic hydrocarbon (generic). (a) Chemical substance... halogenated aromatic hydrocarbon (PMN P-09-540) is subject to reporting under this section for the...

  17. 40 CFR 721.10258 - Aromatic hydrocarbon (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Aromatic hydrocarbon (generic). 721... Substances § 721.10258 Aromatic hydrocarbon (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as aromatic hydrocarbon (PMN...

  18. 40 CFR 721.10259 - Halogenated aromatic hydrocarbon (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Halogenated aromatic hydrocarbon... Specific Chemical Substances § 721.10259 Halogenated aromatic hydrocarbon (generic). (a) Chemical substance... halogenated aromatic hydrocarbon (PMN P-09-540) is subject to reporting under this section for the...

  19. 40 CFR 721.10258 - Aromatic hydrocarbon (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Aromatic hydrocarbon (generic). 721... Substances § 721.10258 Aromatic hydrocarbon (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as aromatic hydrocarbon (PMN...

  20. 40 CFR 721.10259 - Halogenated aromatic hydrocarbon (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Halogenated aromatic hydrocarbon... Specific Chemical Substances § 721.10259 Halogenated aromatic hydrocarbon (generic). (a) Chemical substance... halogenated aromatic hydrocarbon (PMN P-09-540) is subject to reporting under this section for the...

  1. 40 CFR 721.2673 - Aromatic epoxide resin (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Aromatic epoxide resin (generic). 721... Substances § 721.2673 Aromatic epoxide resin (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as aromatic epoxide resin (PMN...

  2. 40 CFR 721.5762 - Aromatic aldehyde phenolic resin (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Aromatic aldehyde phenolic resin... Specific Chemical Substances § 721.5762 Aromatic aldehyde phenolic resin (generic). (a) Chemical substance... aromatic aldehyde phenolic resin (PMN P-01-573) is subject to reporting under this section for...

  3. 40 CFR 721.5762 - Aromatic aldehyde phenolic resin (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aromatic aldehyde phenolic resin... Specific Chemical Substances § 721.5762 Aromatic aldehyde phenolic resin (generic). (a) Chemical substance... aromatic aldehyde phenolic resin (PMN P-01-573) is subject to reporting under this section for...

  4. 40 CFR 721.2673 - Aromatic epoxide resin (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aromatic epoxide resin (generic). 721... Substances § 721.2673 Aromatic epoxide resin (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as aromatic epoxide resin (PMN...

  5. 40 CFR 721.2925 - Brominated aromatic ester.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Brominated aromatic ester. 721.2925... Substances § 721.2925 Brominated aromatic ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a brominated aromatic ester (PMN...

  6. 40 CFR 721.2925 - Brominated aromatic ester.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Brominated aromatic ester. 721.2925... Substances § 721.2925 Brominated aromatic ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a brominated aromatic ester (PMN...

  7. 40 CFR 721.2925 - Brominated aromatic ester.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Brominated aromatic ester. 721.2925... Substances § 721.2925 Brominated aromatic ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a brominated aromatic ester (PMN...

  8. 40 CFR 721.2925 - Brominated aromatic ester.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Brominated aromatic ester. 721.2925... Substances § 721.2925 Brominated aromatic ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a brominated aromatic ester (PMN...

  9. 40 CFR 721.2925 - Brominated aromatic ester.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Brominated aromatic ester. 721.2925... Substances § 721.2925 Brominated aromatic ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a brominated aromatic ester (PMN...

  10. 40 CFR 721.875 - Aromatic nitro compound.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aromatic nitro compound. 721.875... Substances § 721.875 Aromatic nitro compound. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance aromatic nitro compound (PMN P-86-335) is subject to reporting...

  11. 40 CFR 721.750 - Aromatic amine compound.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aromatic amine compound. 721.750... Substances § 721.750 Aromatic amine compound. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance aromatic amine compound (PMN P-86-334) is subject to reporting...

  12. 40 CFR 721.2673 - Aromatic epoxide resin (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Aromatic epoxide resin (generic). 721... Substances § 721.2673 Aromatic epoxide resin (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as aromatic epoxide resin (PMN...

  13. 40 CFR 721.5762 - Aromatic aldehyde phenolic resin (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Aromatic aldehyde phenolic resin... Specific Chemical Substances § 721.5762 Aromatic aldehyde phenolic resin (generic). (a) Chemical substance... aromatic aldehyde phenolic resin (PMN P-01-573) is subject to reporting under this section for...

  14. 40 CFR 721.5762 - Aromatic aldehyde phenolic resin (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Aromatic aldehyde phenolic resin... Specific Chemical Substances § 721.5762 Aromatic aldehyde phenolic resin (generic). (a) Chemical substance... aromatic aldehyde phenolic resin (PMN P-01-573) is subject to reporting under this section for...

  15. 40 CFR 721.2673 - Aromatic epoxide resin (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Aromatic epoxide resin (generic). 721... Substances § 721.2673 Aromatic epoxide resin (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as aromatic epoxide resin (PMN...

  16. Prenatal Exposure to Polycyclic Aromatic Hydrocarbons /Aromatics, BDNF and Child Development

    PubMed Central

    Perera, Frederica; Phillips, David H.; Wang, Ya; Roen, Emily; Herbstman, Julie; Rauh, Virginia; Wang, Shuang; Tang, Deliang

    2015-01-01

    Objectives Within a New York City (NYC) birth cohort, we assessed the associations between polycyclic aromatic hydrocarbon (PAH) and other aromatic DNA adducts and brain derived neurotrophic factor (BDNF) concentrations in umbilical cord blood, and neurodevelopment at age 2 years and whether BDNF is a mediator of the associations between PAH/aromatic-DNA adducts and neurodevelopment. Methods PAH/aromatic-DNA adduct concentrations in cord blood were measured in 505 children born to nonsmoking African-American and Dominican women residing in NYC, and a subset was assessed for neurodevelopment at 2 years using the Bayley Scales of Infant Development Mental Development Index (MDI). A spectrum of PAH/aromatic-DNA adducts was measured using the 32P-postlabeling assay; DNA adducts formed by benzo[a]pyrene (B[a]P), a representative PAH, were measured by High Performance Liquid Chromatography (HPLC)/fluorescence. BDNF mature protein in cord blood plasma was quantified by an ELISA. Multivariate regression analysis, adjusting for potential confounders, was conducted. Results PAH/aromatic-DNA adduct concentration measured by postlabeling was inversely associated with BDNF concentration (p=0.02) and with MDI scores at 2 years (p=0.04). BDNF level was positively associated with MDI scores (p=0.003). Restricting to subjects having all three measures (PAH/aromatic-DNA adducts by postlabeling, MDI, and BDNF), results were similar but attenuated (p=0.13, p=0.05, p=0.01, respectively). Associations between B[a]P-DNA adducts and BDNF and B[a]P-DNA adducts and MDI at age 2 years were not significant. At age 3 years, the positive association of BDNF with MDI was not observed. Conclusions The results at age 2 suggest that prenatal exposure to a spectrum of PAH/aromatic pollutants may adversely affect early neurodevelopment, in part by reducing BDNF levels during the fetal period. However, the same relationship was not seen at age 3. PMID:26301740

  17. Lymphocyte aromatic hydrocarbon responsiveness in acute leukemia of childhood

    SciTech Connect

    Blumer, J.L.; Dunn, R.; Esterhay, M.D.; Yamashita, T.S.; Gross, S.

    1981-12-01

    Aryl hydrocarbon hydroxylase (AHH) activity and inducibility were examined in mitogen-stimulated cultured lymphocytes from children with acute leukemia in remission, with nonleukemic malignancies, and with no family or personal history of malignant disease. Neither morphological differences nor differences in mitogen responsivelness were observed among the three sources of cells studied. Levels of constitutive and dibenzanthracene-induced AHH activity were found to be similar among the three groups by analysis of variance. However, when results were analyzed in terms of inducibility ratios, it was found that cells from leukemic children were significantly less inducible (p < 0.005) than cells from unaffected children or children with nonleukemic malignancies. The reason for this difference became apparent when statistical criteria were employed for the phenotypic separation of individuals who were highly aromatic hydrocarbon responsive and minimally responsive. A significantly larger proportion (p < 0.001) of leukemic children than unaffected children or children with nonleukemic malignancy were found to be minimally aromatic hydrocarbon responsive. Moreover, in patients with acute lymphoblastic leukemia relapsing while on therapy, longer durations of the first remission were correlated (r = 0.63, p < 0.05) with the highly inducible AHH phenotype.

  18. Potential application of aromatic plant extracts to prevent cheese blowing.

    PubMed

    Librán, C M; Moro, A; Zalacain, A; Molina, A; Carmona, M; Berruga, M I

    2013-07-01

    This study aimed to inhibit the growth of Escherichia coli and Clostridium tyrobutyricum, common bacteria responsible for early and late cheese blowing defects respectively, by using novel aqueous extracts obtained by dynamic solid-liquid extraction and essential oils obtained by solvent free microwave extraction from 12 aromatic plants. In terms of antibacterial activity, a total of 13 extracts inhibited one of the two bacteria, and only two essential oils, Lavandula angustifolia Mill. and Lavandula hybrida, inhibited both. Four aqueous extracts were capable of inhibiting C. tyrobutyricum, but none were effective against E. coli. After extracts' chemical composition identification, relationship between the identified compounds and their antibacterial activity were performed by partial least square regression models revealing that compounds such as 1,8 cineole, linalool, linalyl acetate, β-phellandrene or verbene (present in essential oils), pinocarvone, pinocamphone or coumaric acid derivate (in aqueous extracts) were compounds highly correlated to the antibacterial activity. PMID:23417280

  19. Potential application of aromatic plant extracts to prevent cheese blowing.

    PubMed

    Librán, C M; Moro, A; Zalacain, A; Molina, A; Carmona, M; Berruga, M I

    2013-07-01

    This study aimed to inhibit the growth of Escherichia coli and Clostridium tyrobutyricum, common bacteria responsible for early and late cheese blowing defects respectively, by using novel aqueous extracts obtained by dynamic solid-liquid extraction and essential oils obtained by solvent free microwave extraction from 12 aromatic plants. In terms of antibacterial activity, a total of 13 extracts inhibited one of the two bacteria, and only two essential oils, Lavandula angustifolia Mill. and Lavandula hybrida, inhibited both. Four aqueous extracts were capable of inhibiting C. tyrobutyricum, but none were effective against E. coli. After extracts' chemical composition identification, relationship between the identified compounds and their antibacterial activity were performed by partial least square regression models revealing that compounds such as 1,8 cineole, linalool, linalyl acetate, β-phellandrene or verbene (present in essential oils), pinocarvone, pinocamphone or coumaric acid derivate (in aqueous extracts) were compounds highly correlated to the antibacterial activity.

  20. Long-term fate of aromatics derived from crankcase oil in rainbow trout and snow crabs

    SciTech Connect

    Hellou, J.; Banoub, J.H.; Gentil, E.; Andrews, C.; Payne, J.F.; Howse, D.

    1995-12-31

    Crankcase oils are mineral oils containing hydrocarbons and various additives. In the present case, the oil contained 10% aromatics and 1% PAH if concentration is expressed in terms of chrysene units. Rainbow trout were exposed daily to food pellets spiked with crankcase oil and sampled monthly for 4 months. Exposure was to 0, 3.2, 6.4 and 9.6 ug oil/g fish/day and represents a water concentration of nearly 0, 10, 20, and 30 ug oil/L. Muscle tissue was analyzed for total and specific aromatics (PAHs, LABs, PCBs) and various elements. The liver was analyzed for enzymatic activity (EROD and AchE) and the gall bladder, for bile metabolites. A dose and time response was observed for the bioaccumulation of aromatics. In another experiment, crabs were exposed to crankcase oil during 6 months and sampled intermittently. Feeding took place once a week during the first 3 months and biweekly for the last 3 months. Exposure was equivalent to 4--8 ug oil/g crab/day or to 510 ug oil/L. Muscle and hepatopancreas were analyzed for aromatic compounds. Comparison is made between the two experiments and the fate of aromatics discussed in terms of temperature, respiration rates, lipid content of tissues and K{sub ow} of chemicals known to be present in lubricating oils.