Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Polycyclic Compounds”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 613 records · Page 34Linked to original sources
PubMedDate not supplied

Relative potency of PAHs and heterocycles as aryl hydrocarbon receptor agonists in fish.

The relative potency of polycyclic aromatic compounds as aryl hydrocarbon receptor (AhR) agonists in fish was determined using data on CYP1A induction or AhR binding for 74 polycyclic aromatic hydrocarbons (PAHs) and heterocycles in teleost, avian, or mammalian systems from 18 published papers. Each PAH was assigned a fish potency factor relative to the potency of 2,3,7,8-tetrachlorodibenzo-p-dioxin as an AhR agonist. Two and three ring unsubstituted PAHs were generally inactive in fish, avian, and mammalian systems. Benzo[k]fluoranthene and indeno[1,2,3-cd]pyrene were consistently the most potent PAHs, with fish potency factors of 0.001-0.002. Common structural features associated with higher potency PAHs included 4-6 rings containing fluoranthene or phenanthrene structures with an exposed bay region. These results show that PAHs can have similar potency as many dioxin-like PCBs, and AhR mediated toxicity should be considered in assessing the risks of PAHs in fish.

Animals↗
PubMed1985

Nuclear enlargement--an early change produced in mouse epidermis by carcinogenic chemicals applied topically in the presence of a promoter.

A series of 27 compounds, including 11 polycyclic hydrocarbons, 8 proximate carcinogens and 8 other compounds, were tested for their ability to induce epidermal nuclear enlargement in mouse skin. The materials were applied topically in methyl ethyl ketone containing 0.1% croton oil, repetitively for 3 days. Nuclear enlargement present on the fourth day was determined with the aid of a Quantiment image-analysing computer. The results obtained indicated a close correlation between the topical carcinogenicity of the test compounds and their ability to induce epidermal nuclear enlargement in the presence of croton oil.

Administration, Topical↗
PubMed2006

Evidence of genotoxicity related to high PAH content of sediments in the upper part of the Seine estuary (Normandy, France).

In order to characterize the genotoxicity in the Seine estuary and Seine bay, chemical and toxicological analyses were performed on 17 sediments collected in June 2001 and June 2003. Many potent mutagenic and/or carcinogenic compounds - including polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB) and metals - were detected. Those compounds were found to be at relatively high concentrations in the upper part of the Seine estuary but were barely detectable at sites outside the plume from the Seine. The levels of pollution did not vary significantly between the two sampling periods, except that PAH concentrations in sediments collected at Oissel and Le Havre showed a marked increase in June 2003. The toxicity of organic extracts from sediments was evaluated by both embryotoxicity and in vitro genotoxicity (SOS Chromotest) assays. Organic extracts from sediments taken from the Seine estuary appeared significantly more embryotoxic than those from the Seine bay. In addition, the sediment extracts from the upper part of the Seine estuary exhibited higher genotoxicity than those from the lower part, and no genotoxicity was reported for sediments from the Seine bay. The genotoxic activity was detected only after adding an S9 microsomal fraction, suggesting the preponderant involvement of pro-genotoxic organic compounds. In addition, SOS Chromotest responses obtained with purified organic fractions revealed that PAH and, to a lesser extent, unknown polar organic compounds were probably responsible for this genotoxicity. Altogether, these results suggest that sediments from the upper Seine estuary are genotoxic and embryotoxic, and therefore, could be potentially hazardous for species living or feeding in the area.

Animals↗
PubMed2005

The dihydroxyacetone unit--a versatile C(3) building block in organic synthesis.

Nature employs dihydroxyacetone phosphate (DHAP) as the donor component in various enzyme-catalyzed aldol reactions. Probably the most significant example in this regard is photosynthesis, in which D-glucose, the most widespread natural product, is formed in just a few steps from DHAP. In recent years a number of synthetic equivalents of DHAP have been reported that deserve particular attention, as their applicability in organic synthesis is not limited to (stereoselective) aldol reactions. The power of these reagents has also been demonstrated convincingly in numerous other asymmetric electrophilic alpha-substitution reactions in target-oriented syntheses. Furthermore, the related 1,3-dioxins are useful equivalents of 2-substituted acrolein derivatives.

Acrolein↗
PubMed2003

Dynamic covalent approach to [2]- and [3]roxtanes by utilizing a reversible thiol-disulfide interchange reaction.

A dynamic covalent approach to disulfide-containing [2]- and [3]rotaxanes is described. Symmetrical dumbbell-shaped compounds with two secondary ammonium centers and a central located disulfide bond were synthesized as components of rotaxanes. The rotaxanes were synthesized from the dumbbell-shaped compounds and dibenzo-[24]crown-8 (DB24C8) with catalysis by benzenethiol. The yields of isolated rotaxanes reached about 90 % under optimized conditions. A kinetic study on the reaction forming [2]rotaxane 2 a and [3]rotaxane 3 a suggested a plausible reaction mechanism comprising several steps, including 1) initiation, 2) [2]rotaxane formation, and 3) [3]rotaxane formation. The whole reaction was found to be reversible in the presence of thiols, and thermodynamic control over product distribution was thus possible by varying the temperature, solvent, initial ratio of substrates, and concentration. The steric bulk of the end-capping groups had almost no influence on rotaxane yields, but the structure of the thiol was crucial for reaction rates. Amines and phosphines were also effective as catalysts. The structural characterization of the rotaxanes included an X-ray crystallographic study on [3]rotaxane 3 a.

Crystallography, X-Ray↗
PubMed1983

Organic contaminants in the aquatic environment. IV. Analytical techniques.

The analytical techniques available for the determination of organic pollutants in raw, potable and waste waters are reviewed. General measures of organic pollution are considered, together with a range of chromatographic and instrumental methods for the analysis of specific groups of pollutants. Gas liquid chromatography and high performance liquid chromatography are the most widely used techniques for the measurement of specific compounds while mass spectrometry and combined gas liquid chromatography/mass spectrometry are the most definitive methods of analysis. Consideration of the range of sample extraction procedures which are available indicates that solvent extraction procedures are the most suitable for non-volatile organic substances, and gas purging or stripping techniques are favoured for the isolation of volatile compounds. Sample purification or clean-up procedures, including column and thin layer chromatography, are of particular importance when waste water samples are to be analysed, owing to the relatively high concentrations of extraneous materials which have to be removed prior to analysis. The merits and limitations of currently available analytical procedures are discussed.

2-Methyl-4-chlorophenoxyacetic Acid↗
PubMed2006

Inhibition of rainbow trout (Oncorhynchus mykiss) P450 aromatase activities in brain and ovarian microsomes by various environmental substances.

Aromatase, a key steroidogenic enzyme that catalyses the conversion of androgens to estrogens, represent a target for endocrine disrupting chemicals. However, little is known about the effect of pollutants on aromatase enzymes in fish. In this study, we first optimized a rainbow trout (Oncorhynchus mykiss) microsomal aromatase assay to measure the effects of 43 substances belonging to diverse chemical classes (steroidal and non steroidal aromatase inhibitors, pesticides, heavy metals, organotin compounds, dioxins, polycyclic aromatic hydrocarbons) on brain and ovarian aromatase activities in vitro. Our results showed that 12 compounds were able to inhibit brain and ovarian aromatase activities in a dose-dependent manner with IC50 values ranging from the low nM to the high microM range depending on the substance: steroidal and non steroidal inhibitors of aromatase (4-hydroxyandrostenedione, androstatrienedione, aminogluthethimide), imidazole fungicides (clotrimazole, imazalil, prochloraz), triazole fungicides (difenoconazole, fenbuconazole, propiconazole, triadimenol), the pyrimidine fungicide fenarimol and methylmercury. Overall, this study demonstrates that rainbow trout brain and ovarian microsomal aromatase assay is suitable for evaluating potential aromatase inhibitors in vitro notably with respect to environmental screening. The results highlight that methylmercury and some pesticides that are currently used throughout the world, have the potential to interfere with the biosynthesis of endogenous estrogens in fish.

Androstenedione↗
PubMed2004

The genotoxicity of ambient outdoor air, a review: Salmonella mutagenicity.

Mutagens in urban air pollution come from anthropogenic sources (especially combustion sources) and are products of airborne chemical reactions. Bacterial mutation tests have been used for large, multi-site, and/or time series studies, for bioassay-directed fractionation studies, for identifying the presence of specific classes of mutagens, and for doing site- or source-comparisons for relative levels of airborne mutagens. Early research recognized that although carcinogenic PAHs were present in air samples they could not account for the majority of the mutagenic activity detected. The mutagenicity of airborne particulate organics is due to at least 500 identified compounds from varying chemical classes. Bioassay-directed fractionation studies for identifying toxicants are difficult to compare because they do not identify all of the mutagens present, and both the analytical and bioassay protocols vary from study to study. However, these studies show that the majority of mutagenicity is usually associated with moderately polar/highly polar classes of compounds that tend to contain nitroaromatic compounds, aromatic amines, and aromatic ketones. Smog chamber studies have shown that mutagenic aliphatic and aromatic nitrogen-containing compounds are produced in the atmosphere when organic compounds (even non-mutagenic compounds) are exposed to nitrogen oxides and sunlight. Reactions that occur in the atmosphere, therefore, can have a profound effect on the genotoxic burden of ambient air. This review illustrates that the mutagenesis protocol and tester strains should be selected based on the design and purpose of the study and that the correlation with animal cancer bioassay results depends upon chemical class. Future emphasis needs to be placed on volatile and semi-volatile genotoxicants, and on multi-national studies that identify, quantify, and apportion mutagenicity. Initial efforts at replacing the Salmonella assay for ambient air studies with some emerging technology should be initiated.

Air Pollutants↗
PubMedDate not supplied

Synthesis and theoretical study of 2-amino-2,3,3a,4,5,6-hexahydro-1H-phenalene and its biological evaluation on central dopaminergic system.

Compound 2 considered as a rigid non-hydroxylated 2-amino tetralin was synthesized and biologically evaluated. Central administration of compound 2 (50 microg or 100 microg/10 microl) induced a reduction in urinary sodium and potassium excretion at 3 and 6 h of urine collection. We speculate that compound 2 may be acting as a dopamine receptor antagonist.

Amines↗
PubMed1998

Malignant transformation of Syrian hamster kidney cells in vitro by interaction of airborne particulates and simian virus (SV-) 40.

Permanent inhalation of great variety of air pollutants raises serious problems concerning adverse effects on human health. Especially in airborne particulates more than 1000 inorganic and organic compounds have been detected, among them also carcinogens and mutagens, such as polycyclic aromatic hydrocarbons, polycyclic-aza-compounds, carbonic acids, phenols, ketons, heavy metals, etc. The role of airborne particulates in genesis of the most common cancer in man, the bronchogenic carcinoma, is still unresolved. Samples of airborne particulates were collected at locations of the highly industrialized Rhine-Ruhr region (Germany) employing a high volume sampler HVS-150 (Ströhlein Instruments) prepared with glass fibre filters. Samples were extracted in a Soxhlet-apparatus with dichloromethane. Using a rotating evaporator the solvent was evaporated and the residual substances dissolved in dimethylsulfoxide for cell culture experiments. Carcinogenic activity of extracts of airborne particulates was evaluated by the bioassay of 'enhancement' of malignant cell transformation in vitro. In this bioassay, exponentially growing cell cultures from kidneys of the Syrian golden hamster were treated with various concentrations of extracts of airborne particulates for 18 h. Thereafter, exposed and control cultures were infected with the papovavirus simian virus (SV-) 40 (Strain RH 911) at a multiplicity of infection (M.O.I.) of 300-500 ID50. A strong dose-dependent 'enhancement' of cell transformation frequency occurred in kidney cultures of the Syrian golden hamster pretreated with extracts of airborne particulates and thereafter infected with the simian virus 40. It has to be emphasized, that very low quantities of extractable substances corresponding to particulates collected from 0.5 m3 of air, induced a strong highly significant increase in cell transformation frequency. Inoculation of transformed cells into syngeneic animals produced in a high percentage malignant tumors, mostly sarcomas.

Air Pollutants↗