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 253 records · Page 14Linked to original sources
PubMed2002

Stereoselective transition metal-catalyzed and radical polycyclizations.

This short review presents a selection of metal-mediated and radical polycyclizations reported during the past two years. Palladium-catalyzed domino processes, cobalt-mediated cycloadditions and Pauson-Khand reactions catalyzed by rhodium are described. Ruthenium and platinum are shown as powerful metal catalysts in cyclizations, ring-closing metathesis and cycloisomerizations. Finally, recent examples of radical cascades, and their synthetic applications, are selected for their ability to build polycyclic compounds.

Animals↗
PubMed1996

[Developments of highly stereoselective domino reactions and application to medicinal chemistry].

Simple and highly effective methods for the synthesis of polycyclic ring systems via two types of intramolecular domino reactions are developed and presented. The first example is an intramolecular double Michael reaction, whose scope-limitation, mechanism and application to natural product synthesis are discussed. The intramolecular Michael-aldol reaction is the second case, which provides a nice method for the preparation of polycyclic compounds having a four-membered ring system. In addition, some related reactions of these methods are described.

Chemistry, Pharmaceutical↗
PubMed1992

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

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 epsilon 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.

Mutagenicity Tests↗
PubMed1995

Complex formation of heterocyclic amines with porphyrins: its use in detection and prevention.

Porphyrins can suppress mutagenicity of heterocyclic amines. We have shown using the Ames Salmonella test that the mutagenicity of heterocyclic amines is efficiently inhibited by addition of hemin, the red blood porphyrin, in the assay mixture. In this suppression, hemin acts in two ways; inhibition of metabolic activation and suppression of the mutagenicity in the metabolically activated heterocyclic amines. In both of these actions, a complex formation between the porphyrin molecule and the planar molecules of heterocyclic amines seems to play a role. Complex formation and its use in detecting heterocyclic amines in various samples can be seen in the case for copper phthalocyanine, a blue pigment with a porphyrin-like structure. Cellulose bearing copper phthalocyanine trisulfonate as ligand was found to be a selective adsorbent for polycyclic compounds. This adsorbent, named blue cotton/blue rayon, adsorbs polycyclics in aqueous media by forming complexes on the ligand molecules, and releases the adsorbed compounds in organic solvents, such as in methanol plus a small amount of ammonia. The ease in manipulation and its high efficiency have made the blue cotton/blue rayon technique a means now widely used in detecting heterocyclic amines and other polycyclic mutagens in crude samples such as food, urine, and even river water. Chlorophyll, a green plant porphyrin, is another example. Chlorophyll and its stable form, chlorophyllin, have been shown to be inhibitory against the mutagenicity of heterocyclic amines. We have prepared Sepharose-supported chlorophyllin and have shown that heterocyclic amines are adsorbable to this ligand in a reversible fashion. Complex formation between chlorophyllin and heterocyclic amines is also suggested from spectrophotometric studies. A preliminary in vivo study has shown that chlorophyllin is effective in diminishing the cooked beef-derived urinary mutagenicity in humans.

Amines↗
PubMed2001

Determination and multivariate statistical analysis of biochemical responses to environmental contaminants in feral freshwater fish Leuciscus cephalus, L.

Modulations of 11 prospective biochemical markers of impacts of aquatic pollutants in liver tissue of chub (Leuciscus cephalus), caught at several sampling sites of a river with various pollution types and rates, were matched against analytical data of concentrations of organochlorine compounds, polycyclic aromatic hydrocarbons (PAHs), and heavy metals. Multivariate principal component analysis (PCA) of the field data showed general patterns of biochemical responses to different types of pollutants and relationships among the biomarkers. Cytochrome P4501A-dependent 7-ethoxyresorufin O-deethylase (EROD) activity, inducible by 2,3,7,8-tetrachlorodibenzo-p-dioxin and structurally related planar compounds, was strongly enhanced in the more contaminated areas. Compared with polychlorinated aromatic hydrocarbons, PAHs did not contribute so significantly to EROD induction. Testosterone 6 beta- and 16 alpha-hydroxylase activities, as an expression of the cytochrome P4503A27, were slightly increased at several sites but were significantly decreased in samples from some heavily polluted areas. Recently, these activities have been suggested as potential biomarkers of exposure to contaminants that do not induce cytochrome P4501A. In this study, their inhibition or induction was not associated with a specific class of monitored contaminants, and selectivities of these modulations are still to be investigated. Similar modulations of the prospective biochemical indicators of oxidative stress, including microsomal glutathione S-transferase activity, cytosolic glutathione S-transferase with ethacrynic acid, and glutathione reductase, were demonstrated by PCA. The pattern of the modulations of the microsomal nicotinamide adenine dinucleotide phosphate (NADPH)-dependent lipid peroxidation in vitro differed from the responses of the rest of oxidative stress parameters at some sampling sites. Further biochemical markers of oxidative stress under study, including in vivo lipid peroxidation, in vitro production of reactive oxygen species, and the concentration of metallothioneins did not correlate well with the concentrations of the contaminants. Principal component analysis demonstrated that the EROD activity, glutathione-dependent enzymes, and Fe(II)-enhanced lipid peroxidation formed a suitable battery of biomarkers of exposure.

Animals↗
PubMed2000

Deriving ecological risk-based soil quality values in the Basque Country.

Most industrialised countries are currently drawing up their procedures to deal with contaminated land. In the Basque Country generic soil quality values applicable to different land uses have been drawn up for many common soil inorganic and organic pollutants, to assist in the site assessment process. In this paper we present those values aimed at protecting ecosystems as the main target at risk. Ecological risk was defined on the basis of effects on the structure of the soil invertebrate community. Ecotoxicological data from laboratory tests were used in combination with a theoretical extrapolation method. The following groups of compounds were assayed: heavy metals, cyanides, aromatic compounds, polycyclic aromatic hydrocarbons, HCH isomers, chlorinated organic compounds, and mineral oil. A specific toxicity database was created. The reliability of the values obtained as well as the limitations of the derivation process are discussed.

Animals↗
PubMed1978

The mutagenicity of airborne particulate pollutants.

The mutagenic effect of extracts derived from airborne particulate matter was investigated with the Ames-test. The whole extract proved to be distinctly mutagenic. To find out whether the content of polycyclic aromatic hydrocarbons may be responsible for the mutagenic effect, the extract was split into several fractions. The fraction containing the polycyclic compounds showed the lowest mutagenic rate that was enzymatically mediated. The other fractions required metabolic activation for some of their components, but some components were active without metabolic activation.

Air Pollutants↗
PubMed1995

[Mortality due to bronchopulmonary cancers in workers of 2 foundries].

A mortality study was carried out in two factories producing stainless steel in order to assess lung cancer risk among workers employed in coke oven, blast and open hearth furnaces, foundry, electric furnace, hot and cold rolling mills and pickling areas. Occupational exposures of interest were chromium compounds, nickel compounds, polycyclic aromatic hydrocarbons (PAH), silica and asbestos. All male workers having at least one year of employment between 01.01.1960 and 31.12.1990 were followed up for mortality. The vital status was assessed from birth place registries. Complete job histories since date of first employment were abstracted from the company files. The smoking habits of 50% of the cohort members were known from medical records. The observed number of deaths (obs) were compared with the expected ones based on regional rates with adjustment for age, sex and calendar time (Standardized Mortality Ratio, SMR). The cohorts included 6324 (factory 1) and 5270 (factory 2) workers. The overall mortality did not differ markedly from that expected in both factories: SMR = 0.95 (obs = 1540, p = 0.05) in factory 1 and SMR = 1.06 (obs = 916, non-significant) in factory 2. SMRs for lung cancer did not differ from unity, respectively 0.99 (obs = 105) and 1.00 (obs = 54), in whole cohorts. Non-significant lung cancer excesses were observed among workers of some workshops where exposures of interest might have occurred: coke oven (SMR = 2.04), blast furnace (SMR = 1.36), open hearth furnace (SMR = 1.75), hot rolling mills (SMR = 1.29). These processes, however, are no longer involved in the study factories. Furthermore, no lung cancer excess was observed among workers employed in current workshops: electric furnaces and cold rolling mills.

Adult↗
PubMed2001

Development of an analytical method for the simultaneous determination of 15 carcinogenic polycyclic aromatic hydrocarbons and polycyclic aromatic nitrogen heterocyclic compounds. application to diesel particulates.

A new method enabling the determination of 15 priority carcinogenic polyaromatic compounds (PAC) proposed by the US National Toxicology Program (NTP) has been developed and applied to diesel exhaust particulates (DEP). The clean-up procedure consists of solid-phase extraction (SPE) and HPLC fractionation on silica phases followed by liquid-liquid extraction and chromatography on a polyvinylbenzene copolymer column. The method gives good recoveries for all PAC studied except dibenzo[a,j]acridine and dibenzo[a,h]pyrene, for which recovery values are below 80%. The use of GC-MS ion trap and its capacity to achieve single-ion storage enhanced the sensitivity of the method, enabling the detection of high-molecular-weight PAH in the low ng g(-1) concentration range. Intermediate polarity GC columns, e.g. BPX-50 or equivalent, enabled better separation, when applied to DEP analysis, than the generally used DB-5 apolar phase. This is observed mainly for separation of isomeric compounds belonging to the benzofluoranthene and dibenzopyrene families. The application of this method to DEP sampled from the exhaust of a diesel engine and in confined locations such as a tunnel has shown that all PAH of the NTP list could be detected, except dibenzo[a,h]pyrene. No dibenzacridine or dibenzocarbazole could be detected in such matrices. The method is sufficiently sensitive to be applicable to environmental exposure measurements in occupational health surveys.

Algorithms↗
PubMed2000

Evaluation of cytotoxicity, dioxin-like activity and estrogenicity of complex environmental mixtures.

Complex organic extracts from soils and sediments collected in an industrial region of the Czech Republic were tested with in vitro recombinant cell lines for their potential dioxin-like and estrogenic activity and cytotoxicity. For dioxin-like toxicity tested on H4IIE-luc cells complete dose-responses were obtained with all extracts. The MCF-7-luc cell line used for determination of estrogen receptor-mediated activity was sensitive to the cytotoxic effects of the soil and sediment extracts. Dose dependent cytotoxicity was observed with most samples. Significant estrogenic activity was found in all samples. The toxic or estrogenic equivalents based on the analytically determined concentrations of organic pollutants with known dioxin-like or estrogenic potency were calculated and compared to the bioassay-derived estimates. Fractionation along with mass-balance calculation enabled identification of the most active fraction and classes of compounds. Polycyclic aromatic hydrocarbons were identified as the group of compounds responsible for most of the TCDD-like activity as well as for important portion of estrogenic activity.

Czech Republic↗
PubMed2005

Trifluoromethyl derivatives of pentacyclo[5.4.0.0(2,6).0(3,10).0(5,9)]undecane.

Three cage-like polycyclic compounds, viz. exo-8-(trifluoromethyl)pentacyclo[5.4.0.0(2,6).0(3,10).0(5,9)]undecan-endo-8-ol, C12H13F3O, 5-(trifluoromethyl)-4-oxahexacyclo[5.4.1.0(2,6).0(3,10).0(5,9).0(8,11)]dodecan-3-ol, C12H11F3O2, and N-[exo-11-(trifluoromethyl)-endo-11-(trimethylsilyloxy)pentacyclo[5.4.0.0(2,6).0(3,10).0(5,9)]undecan-8-ylidene]aniline methanol solvate, C21H24F3NOSi.CH4O, were obtained from the corresponding oxo derivatives by nucleophilic trifluoromethylation with (trifluoromethyl)trimethylsilane in 1,2-dimethoxyethane solution in the presence of CsF. The crystal structures show that the addition of trifluoromethanide occurs exclusively from the exo face of the polycyclic ketones. Further examination of the crystal structures, together with that of the starting pentacyclo[5.4.0.0(2,6).0(3,10).0(5,9)]undecane-8,11-dione, C11H10O2, showed that increasing substitution at the 8- and/or 11-positions in the cage molecules increases the non-bonded intramolecular C...C distances at the mouth of the cage and changes the puckering of the five-membered rings involving the 8- and 11-positions from an envelope towards a distorted half-chair conformation. Intermolecular co-operative O-H...O hydrogen bonds in the endo-8-ol compound link the molecules into tetramers.

Alkanes↗
PubMed2000

Cloning and expression of genes encoding meta-cleavage enzymes from 4,6-dimethyldibenzothiophene-degrading Sphingomonas strain TZS-7.

Sphingomonas strain TZS-7 was reported as the first strain to have the ability to degrade 4,6-dimethyldibenzothiophene (4,6-dmDBT) by the ring-destructive pathway. Two genes for meta-cleavage dioxygenases were cloned from strain TZS-7. Expression of each gene showed that one enzyme was specific for 2,3-dihydroxybiphenyl while another was more specific for catechol. The genes for the two enzymes were named dmdC and catA. The analysis of deduced amino acid sequences indicates that CatA falls into the class of meta-cleavage dioxygenases acting on dihydroxylated monocyclic compounds and DmdC falls into the class of meta-cleavage dioxygenases acting on dihydroxylated polycyclic compounds.

Amino Acid Sequence↗
PubMed2000

Radical mediated indirect oxidation of a PEG-coupled polycyclic aromatic hydrocarbon (PAH) model compound by fungal laccase.

A high molecular model compound of polycyclic aromatic hydrocarbon was synthesised by coupling pyrene to PEG(5000). The pyrene-PEG was used for the study of a laccase-mediator-system. To prevent direct contact between the substrate and the enzyme the two were kept in their own compartments separated by a membrane. The low molecular mediators, 1-hydroxybenzotriazole and 2, 2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid), which were oxidised by laccase to the corresponding radicals or cations permeated the membrane and reacted with the pyrene-PEG model compound. Oxidation of the model compound resulted in an alpha-oxidation of the alkyl-chain leading to two main oxidation products. The same oxidation products were obtained in the reaction system without a membrane.

Chromatography, High Pressure Liquid↗
PubMed1976

Evaluation of the mutagenicity of compounds of known carcinogenicity, belonging to the benz[a]anthracene, chrysene, and cyclopenta[a]phenanthrene series, using Ames's test.

Fifty-four polycyclic compounds, 29 of the cyclopenta[a]phenanthrene series, 11 chrysenes, and 14 benz[a]anthracenes, have been tested for mutagenicity by Ames's method, using Salmonella typhimurium TA100. Without exception all 37 carcinogens and a known initiator were mutagens. Of the 16 noncarcinogens 7 were mutagenic, but none of these has yet been tested for initiating, as opposed to carcinogenic, activity. There appeared to be little quantitative correspondence between carcinogenic and mutagenic potency, however, and possible reasons for this are discussed. The aryl hydrocarbon hydroxylase inhibitor 7,8-benzoflavone strongly inhibited the mutagenicity of certain compounds when it was added to the incubations.

Animals↗
PubMedDate not supplied

Health risk assessment of urban suspended particulate matter with special reference to polycyclic aromatic hydrocarbons: a review.

Airborne suspended particulate matter is an important marker of air quality. The term 'particulates' includes organic and inorganic matter, nitrogen compounds, sulphur compounds, polycyclic aromatic hydrocarbons (PAHs), several heavy metals, and radionuclides. The health risks from the 'classic' pollutants sulfur dioxide, nitrogen dioxide, ozone, carbon monoxide, and particulates have been comprehensively reviewed. Alarming levels of non-classic pollutants like the PAHs have been reported globally. PAHs have been found in placental tissues of women and in umbilical cord blood samples from newborn babies. The damaged DNA in cord blood is a indication of the fate of these pollutants in the environment. Hence, a need exists for a comprehensive investigation of the human health-related aspects of exposure to particulates and PAHs in the urban environment. This paper reviews the literature on PAHs in conjunction with particulate matter on a global perspective.

Adult↗
PubMed2002

Sol-gel capillary microextraction.

Sol-gel capillary microextraction (sol-gel CME) is introduced as a viable solventless extraction technique for the preconcentration of trace analytes. To our knowledge, this is the first report on the use of sol-gel-coated capillaries in analytical microextraction. Sol-gel-coated capillaries were employed for the extraction and preconcentration of a wide variety of polar and nonpolar analytes. Two different types of sol-gel coatings were used for extraction: sol-gel poly(dimethylsiloxane) (PDMS) and sol-gel poly(ethylene glycol) (PEG). An in-house-assembled gravity-fed sample dispensing unit was used to perform the extraction. The analysis of the extracted analytes was performed by gas chromatography (GC). The extracted analytes were transferred to the GC column via thermal desorption. For this, the capillary with the extracted analytes was connected to the inlet end of the GC column using a two-way press-fit fused-silica connector housed inside the GC injection port. Desorption of the analytes from the extraction capillary was performed by rapid temperature programming (at 100 degrees C/min) of the GC injection port. The desorbed analytes were transported down the system by the helium flow and further focused at the inlet end of the GC column maintained at 30 degrees C. Sol-gel PDMS capillaries were used for the extraction of nonpolar and moderately polar compounds (polycyclic aromatic hydrocarbons, aldehydes, ketones), while sol-gel PEG capillaries were used for the extraction of polar compounds (alcohols, phenols, amines). The technique is characterized by excellent reproducibility. For both polar and nonpolar analytes, the run-to-run and capillary-to-capillary RSD values for GC peak areas remained under 6% and 4%, respectively. The technique also demonstrated excellent extraction sensitivity. Parts per quadrillion level detection limits were achieved by coupling sol-gel CME with GC-FID. The use of thicker sol-gel coatings and longer capillary segments of larger diameter (or capillaries with sol-gel monolithic beds) should lead to further enhancement of the extraction sensitivity.

Journal Article↗
PubMed1991

Biodegradation of halogenated organic compounds.

In this review we discuss the degradation of chlorinated hydrocarbons by microorganisms, emphasizing the physiological, biochemical, and genetic basis of the biodegradation of aliphatic, aromatic, and polycyclic compounds. Many environmentally important xenobiotics are halogenated, especially chlorinated. These compounds are manufactured and used as pesticides, plasticizers, paint and printing-ink components, adhesives, flame retardants, hydraulic and heat transfer fluids, refrigerants, solvents, additives for cutting oils, and textile auxiliaries. The hazardous chemicals enter the environment through production, commercial application, and waste. As a result of bioaccumulation in the food chain and groundwater contamination, they pose public health problems because many of them are toxic, mutagenic, or carcinogenic. Although synthetic chemicals are usually recalcitrant to biodegradation, microorganisms have evolved an extensive range of enzymes, pathways, and control mechanisms that are responsible for catabolism of a wide variety of such compounds. Thus, such biological degradation can be exploited to alleviate environmental pollution problems. The pathways by which a given compound is degraded are determined by the physical, chemical, and microbiological aspects of a particular environment. By understanding the genetic basis of catabolism of xenobiotics, it is possible to improve the efficacy of naturally occurring microorganisms or construct new microorganisms capable of degrading pollutants in soil and aquatic environments more efficiently. Recently a number of genes whose enzyme products have a broader substrate specificity for the degradation of aromatic compounds have been cloned and attempts have been made to construct gene cassettes or synthetic operons comprising these degradative genes. Such gene cassettes or operons can be transferred into suitable microbial hosts for extending and custom designing the pathways for rapid degradation of recalcitrant compounds. Recent developments in designing recombinant microorganisms and hybrid metabolic pathways are discussed.

Bacteria↗