SEARCH · PubMed Health

Results for “aromatic compound”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10Linked to original sources

PubMed2002

Comparative study of four QSAR models of aromatic compounds to aquatic organisms.

Quantitative structure-activity relationships (QSARs) were developed for 43 aromatic compounds toxicity to Photobacterium phosphoreum and Daphnia magna based on four methods: octanol/water partition coefficient, linear solvation energy relationship, molecular connectivity index and group contribution. Through the evaluation of four QSAR methods, LSER was proved to be the best. And it applied to the widest range of chemicals with the greatest accuracy.

Aniline Compounds↗

PubMed2002

Specific and global regulation of genes associated with the degradation of aromatic compounds in bacteria.

A large number of bacteria are able to degrade aromatic carbon sources employing different strategies. All these pathways are objects of regulatory control at the level of gene expression. This includes specific control in response to the availability of the respective substrate and in many cases global control responding to other available carbon sources or to the metabolic status of the cell. Here, the regulatory proteins responsible for gene regulation are reviewed in particular in correlation to other proteins with a similar primary structure. Most common is the appearance of regulators of the LysR family; other abundant regulator types are NtrC/XyIR-type proteins, AraC/XyIS-type proteins and the IcIR-type proteins. Almost all of the regulators exert their effects as activators of gene expression with the exception of the GntR-type proteins, which are exclusively described as repressors. Factors involved in individual cases of global regulatory mechanisms are enterobacterial CAP, (p)ppGpp, Crc protein, and direct modification of a specific regulator. However, for most pathways of aromatic compound degradation, the molecular mechanisms causing global regulation are not understood.

Bacteria↗

PubMed2006

Oxygen-dependent regulation of the central pathway for the anaerobic catabolism of aromatic compounds in Azoarcus sp. strain CIB.

The role of oxygen in the transcriptional regulation of the PN promoter that controls the bzd operon involved in the anaerobic catabolism of benzoate in the denitrifying Azoarcus sp. strain CIB has been investigated. In vivo experiments using PN::lacZ translational fusions, in both Azoarcus sp. strain CIB and Escherichia coli cells, have shown an oxygen-dependent repression effect on the transcription of the bzd catabolic genes. E. coli Fnr was required for the anaerobic induction of the PN promoter, and the oxygen-dependent repression of the bzd genes could be bypassed by the expression of a constitutively active Fnr* protein. In vitro experiments revealed that Fnr binds to the PN promoter at a consensus sequence centered at position -41.5 from the transcription start site overlapping the -35 box, suggesting that PN belongs to the class II Fnr-dependent promoters. Fnr interacts with RNA polymerase (RNAP) and is strictly required for transcription initiation after formation of the RNAP-PN complex. An fnr ortholog, the acpR gene, was identified in the genome of Azoarcus sp. strain CIB. The Azoarcus sp. strain CIB acpR mutant was unable to grow anaerobically on aromatic compounds and it did not drive the expression of the PN::lacZ fusion, suggesting that AcpR is the cognate transcriptional activator of the PN promoter. Since the lack of AcpR in Azoarcus sp. strain CIB did not affect growth on nonaromatic carbon sources, AcpR can be considered a transcriptional regulator of the Fnr/Crp superfamily that has evolved to specifically control the central pathway for the anaerobic catabolism of aromatic compounds in Azoarcus.

Amino Acid Sequence↗

PubMed1986

Biotransformation of polycyclic aromatic compounds by fungi.

Incubations of several polycyclic aromatic hydrocarbons (PAHs) and heteroaromatic compounds with a series of common micro-organisms have been performed. The PAHs were not metabolized by any of the fungi studied. The sulphur-containing heterocyclic aromatic compounds dibenzothiophene, thioxanthone and thiochromanone were oxidized at sulphur by C. elegans. Other fungi are capable of oxidation at the sulphur atom of dibenzothiophene and thioxanthone. C-1 and C-3 methyl substituted thioxanthones are hydroxylated at the methyl group by C. elegans.

Biotransformation↗

PubMed2005

Asymmetric hydrogenation of aromatic compounds.

The asymmetric hydrogenation of aromatic and heteroaromatic compounds arguably presents one of the most attractive methods for the synthesis of six-membered cyclic compounds. In recent years, a number of promising stereoselective methods for the asymmetric hydrogenation of pyridines and related heterocycles have been reported.

Journal Article↗

PubMed1994

9-Methoxytariacuripyrone, a naturally occurring nitro-aromatic compound with strong mutagenicity in Salmonella typhimurium.

9-Methoxytariacuripyrone, a nitro-aromatic compound isolated from Aristolochia brevipes showed strong mutagenic activity in strain TA98, TA100 and some YG strains of Salmonella typhimurium with and without S9 mix. Incubation with cytosol resulted in a heavy increase in mutagenicity. When incubated with microsomes the activity was dramatically decreased. The results are discussed in view of the enzymes possibly involved in activation and detoxification of the compound. The role of the basic structure on the mutagenicity mediated through the nitro group was also considered.

Animals↗

PubMed1994

Sensing of aromatic compounds by the DmpR transcriptional activator of phenol-catabolizing Pseudomonas sp. strain CF600.

The dmp operon of the pVI150 catabolic plasmid of Pseudomonas sp. strain CF600 encodes the enzymes involved in the catabolism of phenol and methylphenols. The regulator of this dmp pathway, DmpR, is a member of the NtrC family of transcriptional activators and controls transcription of the dmp operon in response to aromatic effector compounds (V. Shingler, M. Bartilson, and T. Moore, J. Bacteriol. 175:1596-1604, 1993). Using a lux gene fusion reporter system, in which the DmpR-regulated operon promoter controls the expression of luciferase activity, we have shown in the study reported here that DmpR is activated by, but responds differentially to, the presence of a wide range of aromatic compounds. In many microbial regulatory systems, including some members of the NtrC family, the response to environmental fluctuations involves information transfer from surface sensory proteins to transcriptional regulators. However, DmpR-mediated activation of phenol metabolism in response to aromatic compounds occurs in the absence of a specific sensory protein. We used hybrids between DmpR and XylR, a structurally related regulator of toluene and xylene metabolism, to demonstrate that it is the amino-terminal domains of these regulators that determine the specificity of transcriptional activation. The results suggest that it is the direct interaction of aromatic compounds with the DmpR and XylR proteins that regulates their transcriptional promoting activity.

Amino Acid Sequence↗

PubMed2001

Solvent-free asymmetric aminoalkylation of electron-rich aromatic compounds: stereoselective synthesis of aminoalkylnaphthols by crystallization-induced asymmetric transformation.

Electron-rich aromatic compounds such as 2-naphthol give a faster and asymmetric 1-aminoalkylation with high yields when treated with (R)-1-phenylethylamine and aromatic aldehydes in solvent-free conditions. An asymmetric transformation of a second kind, probably induced by the preferential crystallization of one diastereomer, affords the straightforward and stereoselective synthesis of aminoalkylnaphthols. Mechanisms predictable for this asymmetric reaction are reported. The absolute configurations and the conformations of the unknown aminonaphthols are widely ascertained.

Journal Article↗

PubMed2002

Interactions of cyclodextrins with aromatic compounds studied by vibrational circular dichroism spectroscopy.

The host/guest complexation between cyclodextrins (CDs) and aromatic compounds was studied by vibrational circular dichroism (VCD) spectroscopy in mid-IR region. Benzoic acid, 4-aminobenzoic acid, and 2,6-naphthalene-dicarboxylic acid acting as the guests with aromatic skeleton, cause the significant changes in VCD patterns of CD, which indicate that the secondary hydroxyl groups of the CDs are involved in the host/guest complexation. In addition, the intensities and dissymmetry factors (deltaA/A) of the VCD bands, which belong to skeletal CD vibrations, depend on the sizes of the guest molecules. Our results indicate that the formation of the CD inclusion complexes can be followed by VCD spectroscopy.

Benzoates↗

PubMed2002

Humic acid complexation of basic and neutral polycyclic aromatic compounds.

Complexation by humic acid (HA) of basic (quinoline) and neutral (naphthalene) polycyclic aromatic compounds (PACs) was compared using fluorescence spectroscopy and equilibrium dialysis (ED). These compounds sorb to HA via cation exchange and hydrophobic interactions, respectively. Ionization of quinoline strongly affects its sorption to HA; maximum sorption is observed at pH close to logKb (4.92), and competition with H+ and electrolyte cation (Li+) is evident. Spectroscopic experiments indicate that quinolinium (QH+) cation fluorescence is quenched via a static mechanism (i.e., a dark complex is formed) when the protonated form is adsorbed via ion exchange to HA. The extent of sorption, calculated from fluorescence data using the Stern-Volmer equation, was compared to independent ED measurements. Although both methods indicated the same trends with solution chemistry, fluorescence quenching data suggested more extensive complexation than that measured using ED. In contrast to ionizable PACs, studied here and previously, interaction of naphthalene with HA is unaffected by changes in solution conditions (pH, ionic strength).

Adsorption↗

PubMed2000

Two glycolipids increase in the bioremediation of halogenated aromatic compounds.

Two bacterial glycolipids were applied for the bioremediation of mono-halogenated aromatic compounds in soil. 4-Chloro-1-naphthol (CN) and 3-chlorodiphenylamine (CDA) were rinsed from a polluted soil sample using a biosurfactant, rhamnolipid. Deemulsification by pH adjustment to 4.0 resulted in about 90% recovery of CN and CDA in an organic solvent fraction which was finally solidified by evaporation. For the bioremediation of the aqueous phase, a bacterial glycoglycerolipid, di-O-12-methyl-tetradecanoyl-3-O-beta-D-galactopyranosyl-sn-glycerol was used to decrease the level of cellular damage induced by the effects of oxygen radical of the intermediate metabolites of CN and CDA. The glycoglycerolipid at a concentration of 100 mg/l increased the cellular resistance to those CN and CDA approximately three fold. Instead of the addition of purified glycoglycerolipid, a 0.1%-volume addition of the culture supernatant of a glycoglycerolipid producer to active sludge was also effective.

Journal Article↗

PubMed2006

The prediction of isotopic patterns in phenylpropanoids from their precursors and the mechanism of the NIH-shift: basis of the isotopic characteristics of natural aromatic compounds.

The theoretical 2H-distribution in the aromatic ring of phenylpropanoids can be predicted from that of their precursors--erythrose-4-phosphate, phosphoenolpyruvate and NADPH--and by invoking the mechanism of the NIH-shift and implied deuterium isotope effects. For each position in the non-oxygenated ring, the predicted natural 2H-abundance is in excellent agreement with experimental data obtained from quantitative 2H NMR-measurements on natural compounds, especially concerning the relative 2H-abundances p > o > or = m. For the p-hydroxylated derivatives, the experimentally determined 2H-abundance sequence order m > o can also be deduced, assuming an anisotropic migration (intramolecular isotope effect) of the p-hydrogen atom to the two differently 2H-substituted m-positions during the NIH-shift (intramolecular hydrogen transfer) and an in vivo deuterium kinetic isotope effect of approximately 1.20 on the final hydrogen elimination from the proposed ketodiene intermediate. The predicted 2H-distribution pattern of methyl salicylate 10, a representative of an o-hydroxylated natural compound, is in excellent agreement with that reported from 2H NMR analyses. However, for salicyl alcohol, minor differences between the theoretical and experimentally determined pattern are found that cannot yet be satisfactorily explained. On the other hand, a very good agreement is found between the theoretical and experimental pattern of coumarin, provided a deuterium kinetic isotope effect of approximately 1.30 is assumed for the elimination of the H-atoms from the ketodiene intermediate. The secondary m-hydroxylation of p-coumaric acid in the biosynthesis of vanillin seems to proceed without large isotope effects. Parallel differences are also observed for the 18O-kinetic isotope effects on the corresponding monooxygenase-catalysed reactions. The results demonstrate convincingly that the mechanisms of these general reactions of the phenylpropanoid biosynthetic pathway are identical and follow general principles. Small observed differences between the 2H-patterns of individual natural aromatic compounds originating from the same hydroxylation type can therefore be assigned to differences of the patterns of the precursors, the extent and the orientation of the hydrogen migration, and the kinetic isotope effect on the final hydrogen elimination. The evidence for the existence of general systematic rules governing isotopic patterns in the shikimic acid pathway and its subsequent reactions is further supported by the recently reported 13C-distribution pattern of vanillin, which is also in agreement with that predicted from the precursors. Hence, it is apparent that the systematics of the isotope patterns of phenylpropanoids are in line with the generally accepted biosynthetic reactions in the shikimic acid pathway and that this knowledge can strengthen their value as an essential support for the distinction of natural and synthetic aromatic compounds.

Benzaldehydes↗

PubMed2001

Growth of the purple bacterium Rhodobacter capsulatus on the aromatic compound hippurate.

The purple nonsulfur bacterium Rhodobacter capsulatus strain B10 grew phototrophically on the aromatic compound hippurate (N-benzoyl-L-glycine) and related benzoyl amino acids. Absorption spectra, extraction, and GC/MS analysis of culture supernatants showed that hippurate was stoichiometrically converted to benzoate and glycine, with the latter used as a carbon or nitrogen source for growth. This conclusion was supported by detection of the enzyme hippuricase in permeabilized intact cells. Chemotrophic growth on hippurate by Rba. capsulatus, either at full or reduced oxygen tensions, was not observed. The type strain of Rhodobacter sphaeroides as well as four strains of Rhodopseudomonas palustris also grew phototrophically on hippurate, while several other aromatic-degrading species of purple bacteria did not.

Benzoates↗

PubMed2006

Validated analytical strategy for the determination of polycyclic aromatic compounds in marine sediments by liquid chromatography coupled with diode-array detection and mass spectrometry.

The aim of this work was to optimise and validate the experimental conditions for the analysis of 20 polycyclic aromatic compounds (PACs) [19 polycyclic aromatic hydrocarbons (PAHs) and dibenzothiophene as polycyclic aromatic sulphur heterocycle (PASH)] in marine sediments by reversed-phase high-performance liquid chromatography (LC) coupled to photodiode array detection (DAD) and to mass spectrometry (MS). The LC-MS interface used was atmospheric pressure chemical ionization (APCI) in the positive ion mode. The operational parameters of the APCI interface and MS detection, such as organic modifier, fragmentation voltage, gain, vaporizer temperature, corona current, capillary voltage, drying gas (N2) and nebulizer pressure, were studied. The sediments were subjected to microwave-assisted solvent extraction (MAE) and clean-up by solid-phase extraction (SPE). The relevance of the selected PACs lies in the fact that 16 PACs are classified by the US Environmental Protection Agency as priority pollutants; 17 PACs are detected in the Prestige oil spill; and 8 PACs are included in the priority substance list of the EU water policy. Recoveries from 47% to 102% were obtained for SRM 1944 certified reference sediment. The limits of quantitation were lower than 100 ngg(-1) dry weight for most PACs, and good precision was achieved.

Atmospheric Pressure↗

PubMed2005

Structural and replicative diversity of large plasmids from sphingomonads that degrade polycyclic aromatic compounds and xenobiotics.

The plasmids from 16 sphingomonads which degrade various xenobiotics and polycyclic aromatic compounds were compared with the previously sequenced plasmid pNL1 from Sphingomonas aromaticivorans F199. The replicase genes repAaAb from plasmid pNL1 were amplified by PCR and used as a gene probe for the identification of plasmids belonging to the same incompatibility group as plasmid pNL1. Plasmids were prepared from various sphingomonads and hybridized with the repA gene probe. Positive hybridization signals were obtained with plasmids of approximately 160-195 kb from Sphingomonas subterranea and S. aromaticivorans B0695, which had been isolated from the same subsurface location as S. aromaticivorans F199. The repA probe also hybridized with plasmids from Sphingomonas xenophaga BN6, Sphingomonas sp. HH69 and Sphingomonas macrogoltabidus, which had been isolated from different continents and which utilize different organic compounds than S. aromaticivorans F199 and the other subsurface strains. The results of the hybridization experiments were confirmed by PCR experiments using primers deduced from the repAaAb region of plasmid pNL1. Nucleotide sequence comparisons suggested that three gene clusters were conserved between plasmid pNL1 and plasmid pBN6 from the naphthalenesulfonate- degrading strain S. xenophaga BN6. From these sequence comparisons, PCR primers were derived in order to detect the respective gene clusters in the other strains and to deduce their position relative to each other. These experiments demonstrated that all analysed subsurface strains harboured the same three gene clusters, but that the position and distance from each other of the clusters varied considerably among the different strains.

Biodegradation, Environmental↗

PubMed2003

The application of high-performance liquid chromatography humic acid columns in determination of Koc of polycyclic aromatic compounds.

An improvement of a method for determination of the distribution coefficient for polycyclic aromatic compounds (PAC) between organic carbon and water (Koc) by high-performance liquid chromatography (HPLC) is presented in this paper. By use of silica-based HPLC columns with chemically immobilized humic acid (Aldrich, Zigma-Aldrich, Taufkirchen, Germany), the retention of PAC to humic acid can be measured, and the results can, when they are compared to those from a blank column, be used to a direct determination of Koc. These values agree quite well with literature Koc values for two- to four-ringed PAC. Our work has shown that it is possible to use this method to investigate how environmental parameters like electrolyte concentration, pH, and temperature affect the sorption of PAC to humic acid. Thermodynamic parameters can be estimated from variable temperature experiments. The advantage of the method is its cost and manpower effectiveness.

Chromatography, High Pressure Liquid↗

PubMed1990

Evaluation of the carcinogenic potency of 4 environmental polycyclic aromatic compounds following intrapulmonary application in rats.

The carcinogenic potential of 4 highly purified polycyclic aromatic compounds (PAC) was studied in the respiratory tract of rats. Using a beeswax/trioctanoin mixture as vehicle, 10, 3 and 1 mg phenanthrene (PHE), 3 and 1 mg chrysene (CHR), 0.1 mg dibenz(a,h)anthracene (DBahA) and 6, 3 and 1 mg benzo(b)naphto(2,1-d)thiophene (BNT) were injected into the lungs of 35 female Osborne-Mendel rats per group. Benzo(a)pyrene (BaP, 0.3, 0.1 and 0.03 mg) was used as the reference substance. Whereas only one squamous cell carcinoma developed at the highest PHE dose, a dose-dependent tumor incidence was found for CHR. BNT showed a carcinogenic effect similar to CHR, but an increasing incidence of neoplasms was not seen between the median and high dose. DBahA induced carcinomas in even more than half of the animals at the dose level of 0.1 mg and, therefore, has to be classified as the most potent PAC under investigation. BaP resulted in a clear dose-response relationship. According to probit analysis of the results, the carcinogenic potencies of the PAC relative to BaP (1.00) rank as follows: DBahA, 1.91; CHR, 0.03; BNT, 0.02; and PHE, 0.001. The estimated ED10- values were 0.031 mg for BaP, 0.016 mg for DBahA, 1.02 mg for CHR, 1.65 mg for BNT and 22.84 mg for PHE.

Animals↗

PubMed2002

Effects of eight polycyclic aromatic compounds on the survival and reproduction of Enchytraeus crypticus (Oligochaeta, Clitellata).

The effects of eight polycyclic aromatic compounds (PACs) on the survival and reproduction of the enchytraeid worm Enchytraeus crvpticus were investigated in an agricultural soil with an organic carbon content of 1.6%. With the exception of acridine, which showed a strong binding to the test soil and a subsequent low toxicity, polycyclic aromatic hydrocarbons and neutral N-, S-, O-monosubstituted analogues showed a similar toxicity to the enchytraeids. Concentrations estimated to give a 10% reduction of reproductive output (EC10 values) were based on measured initial concentrations and were, for acridine, 310 mg/kg; for carbazole, 19 mg/kg; for dibenzofuran, 36 mg/kg, for dibenzothiophene, 40 and 45 mg/kg (two tests); for fluoranthene, 15 mg/kg; for fluorene, 25 mg/kg; for phenanthrene, 40 mg/kg; and for pyrene, 11 mg/kg. Using reported soil-pore-water partitioning coefficients for the substances in question, equilibrium pore-water concentrations could be estimated from the total soil concentrations. Calculated EC10 values, expressed as log10(mmol/L pore water), were negatively related to the lipophilicity (log Kow) of the compounds (r2 = 0.58; p = 0.027, n = 8), thus indicating a rather nonspecific (narcotic) mode of toxic action for these compounds. When compared with literature ecotoxicity data for a springtail (Folsomia fimetaria) tested in the same soil type, enchytraeids generally seem less sensitive.

Animals↗