Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Pyrenes”

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 919 records · Page 51Linked to original sources
PubMed2005

Effect of byproducts from the ozonation of pyrene: biphenyl-2,2',6,6'-tetracarbaldehyde and biphenyl-2,2',6,6'-tetracarboxylic acid on gap junction intercellular communication and neutrophil function.

In this study, biphenyl-2,2',6,6'-tetracarbaldehyde, an initial byproduct formed from the ozonation of pyrene, and biphenyl-2,2',6,6'-tetracarboxylic acid, a subsequent pyrene ozonation byproduct, were evaluated using two toxicology assays to compare the toxicity of ozonation byproducts with that of the parent compound. The first assay measured the potential for the compounds to block gap junctional intercellular communication (GJIC) using the scrape loading/dye transfer technique in normal WB-344 rat liver epithelial cells. The second assay evaluated the ability of the compounds to affect neutrophil function by measuring the production of superoxide in a human cell line (HL-60). Pyrene significantly blocked intercellular communication (f = 0.2-0.5) at 40 microM and complete inhibition of communication (f < 0.2) occurred at 50 microM. Gap junctional intercellular communication in cells exposed to biphenyl-2,2',6,6'-tetracarbaldehyde reached f < 0.5 at a concentration of 15 microM. At concentrations greater than 20 microM, biphenyl-2,2',6,6'-tetracarbaldehyde was cytotoxic and the inhibition of GJIC was caused by cell death. Biphenyl-2,2',6,6'-tetracarboxylic acid was neither cytotoxic nor inhibitory to GJIC at the concentrations tested (10-500 microM). Exposure to biphenyl-2,2',6,6'-tetracarbaldehyde resulted in a concentration-dependent decrease in phorbol 12-myristate 13-acetate-stimulated O2- production. Neither exposure to pyrene nor biphenyl-2,2',6,6'-tetracarboxylic acid caused a significant toxic effect on neutrophil function.

Aldehydes↗
PubMed2002

Studies on the effect of soil aging on the toxicity of pyrene and phenanthrene to a soil-dwelling springtail.

Soil samples spiked with five concentrations of pyrene and phenanthrene were aged for 0, 10, 40, and 120 d before toxicity was investigated using a standardized bioassay with the soil-dwelling collembolan Folsomia fimetaria L. Toxic effects were measured as reductions in survival and reproductive output after 3 weeks of exposure. Both pyrene and phenanthrene were degraded in the test system during storage, phenanthrene to a higher degree than pyrene. However, when toxic effects of the tested substances were calculated on the basis of measured concentrations of the parent compounds, toxicity was unaffected by storage for up to 120 d. Many studies have shown a negative correlation between aging and the biodegradation of polycyclic aromatic hydrocarbons (PAHs), indicating a reduction in the bioavailability of PAHs to micro-organisms with time. Our results indicate that a reduction in toxicity, as related to the measured concentrations of the parent compounds in the soil, may not always be expected for aged soils. Provided that metabolites of pyrene and phenanthrene did not significantly contribute to the toxicity in aged soil samples, a possible explanation for the absence of aging effects is the high test concentrations used in combination with the low content of organic carbon (1.6%) in the test soil.

Animals↗
PubMed2007

Effects of tree root-derived substrates and inorganic nutrients on pyrene mineralization in rhizosphere and bulk soil.

This study investigated the effects of organic and inorganic nutrients on the microbial degradation of the common soil contaminant pyrene. The material used in this investigation was collected from potted trees that had been growing for over a year in a soil artificially contaminated with polycyclic aromatic hydrocarbons. Soil was removed from the nonroot (bulk) and root (rhizosphere) zones of these pots and used in mineralization studies that tracked microbial degradation of 14C-pyrene. The factors influencing degradation in these zones were then tested by amendment with essential inorganic nutrients or with root-derived materials. As expected, pyrene mineralization was greater in soil removed from the rhizosphere than in bulk soil. The rate of mineralization in rhizosphere soil was inhibited by inorganic nutrient amendment, whereas nutrients stimulated mineralization in the bulk soil. Pyrene mineralization in bulk soil was also increased by the addition of root extracts intended to mimic exudation by living roots. However, amendment with excised fine roots that were allowed to decay over time in soil initially inhibited mineralization. With time, the rate of mineralization increased, eventually exceeding that of unamended bulk soil. Combined, the initial inhibition and subsequent stimulation produced a zero net impact of decaying fine roots on bulk soil mineralization. Our results, in conjunction with known temporal patterns of fine root dynamics in natural systems, support the idea that seasonal variations in nutrient and substrate availability may influence the long-term effect of plants on organic degradation in soil, possibly reducing or negating the beneficial effects of vegetation that are often observed in short-term studies.

Plant Roots↗
PubMed1981

Activation of benzo(a)pyrene and 2-acetamidofluorene to mutagens by microsomal preparations from different animal species: role of cytochrome P-450 and P-448.

1. The metabolic activation of benzo(a)pyrene and 2-acetamidofluorene to mutagens was studied with liver microsomal preparations from rat, guinea-pig, hamster and mouse, untreated or pretreated with phenobarbitone or 3-methylcholanthrene. 2. Liver microsomal preparations from all animal species activated benzo(a)pyrene, that from mouse being the most efficient. Similarly, microsomal preparations from guinea-pig, hamster and mouse could activate 2-acetamidofluorene, but that from rat exhibited very weak activity. 3. Activation of benzo(a)pyrene into mutagenic intermediates by liver microsomal preparations was increased for all animals except mouse by pretreatment with 3-methylcholanthrene. In contrast, pretreatment with phenobarbitone decreased the activation by microsomal preparations from all species. 4. Activation of 2-acetamidofluorene by liver microsomal preparations from rat and guinea-pig, but not mouse and hamster, was increased by pretreatment of the animals with phenobarbitone. Pretreatment with 3-methylcholanthrene decreased the activation of this carcinogen by microsomal preparations from all species. 5. The metabolic activation of benzo(a)pyrene is catalysed by cytochrome P-448 but not cytochrome P-450. 6. The activation of 2-acetamidofluorene to mutagens may involve, in addition to the mixed-function oxidases, other microsomal enzyme systems.

2-Acetylaminofluorene↗
PubMed1982

Metabolism and subsequent covalent binding of benzo[a]pyrene to macromolecules in gonads and liver of ripe english sole (Parophrys vetulus).

1. Ripe English sole (Parophrys vetulus) force-fed [3H]benzo[a]pyrene, contained 1% of the dose in liver, 0.2% in ovary and 0.1% in testis, after 24 h. No significant change occurred in levels of radioactivity from 24 to 168 h. 2. Gonads and blood contained substantially larger proportions of unchanged benzo[a]pyrene (15-37% of tissue radioactivity) and organic solvent-soluble metabolites (6-35%) than did liver and bile. 3. T.l.c. revealed the presence of phenols, quinones, 7,8-dihydro-7, 8-dihydroxy- and 9,10-dihydro-9,10-dihydroxy-benzo[a]pyrene in liver and gonads. 4. A small proportion (less than 10%) of the radioactivity in liver and gonads was present as glucuronides and sulphates; bile contained a higher proportion (ca. 20%) of total radioactivity as glucuronides and sulphates. 5. Benzo[a]pyrene intermediates were covalently bound to liver proteins and DNA, and to a lesser extent to gonadal proteins (male and female fish) and gonadal DNA (confirmed for testis only).

Administration, Oral↗
PubMed1987

Inhibition of cytochrome P-450c-mediated benzo[a]pyrene hydroxylase and ethoxyresorufin O-deethylase by dihydrosafrole.

1. Inhibitory activity of dihydrosafrole towards benzo[a]pyrene (BP) hydroxylase activity in hepatic microsomes from beta-naphthoflavone (BNF)-induced rats, and in reconstituted systems containing cytochrome P-450c, increased dramatically on preincubation of the inhibitor with NADPH; no inhibition occurred without preincubation. The level of BP hydroxylase inhibition was associated with the progressive formation of the 456 nm dihydrosafrole metabolite-cytochrome P-450c spectral complex during preincubation. 2. Inhibition of BP hydroxylase by dihydrosafrole in control microsomes, and inhibition of ethoxyresorufin O-deethylase (EROD) in microsomes (control or BNF-induced) and in reconstituted systems with cytochrome P-450c, did not require preincubation and apparently was not dependent on prior formation of the dihydrosafrole metabolite-cytochrome P-450 complex. 3. Kinetic studies established that, following preincubation with NADPH, dihydrosafrole was a noncompetitive inhibitor of both BP hydroxylase and EROD activities. In the absence of preincubation, dihydrosafrole was an effective competitive inhibitor of EROD in BNF-induced microsomes and in reconstituted systems with cytochrome P-450c. 4. Both ethoxyresorufin and benzo[a]pyrene inhibited the development of the type I optical difference spectrum of dihydrosafrole in reconstituted systems containing cytochrome P-450c. Inhibition by ethoxyresorufin was competitive while that caused by benzo[a]pyrene was noncompetitive in nature. 5. The type II ligand phenylimidazole was an effective noncompetitive inhibitor of EROD activity but failed to exert any inhibitory effect on cytochrome P-450c-mediated BP hydroxylase activity. Phenylimidazole inhibited formation of the dihydrosafrole type I optical difference spectrum non-competitively. 6. The results indicate that ethoxyresorufin and benzo[a]pyrene may occupy different binding sites on cytochrome P-450c and that dihydrosafrole binds primarily to the site utilized by ethoxyresorufin.

Animals↗
PubMed2000

Application of gel permeation chromatography and HPLC method with fluorescence detector to determination of benzo(a)pyrene in food samples.

During the last three decades contamination of food by traces of toxic substances has been the object of intensive research in modern food toxicology. Various classes of compounds of different origin were detected in food and beverages. In particular nitrosamines and polynuclear aromatic hydrocarbons attracted attention, due to their mutagenic and cancerogenic potential (1, 2). Traces of PAHs have been detected in many foods, including vegetables, vegetable oils, fruits, grains, sea food, grilled and roasted meat, smoked fish, coffee and tea. PAHs in food are only a part of the general problem of PAH pollution in the environment. The numerous types of PAHs--some 100 have been isolated and identified in food and in the environment--are a challenge to modern analytical technique. Various chromatographic procedures, including column, paper and thin layer chromatography have been applied to isolate these substances from contaminated samples. Some of these methods give satisfactory results, especially in the determination of single PAHs including benzo(a)pyrene (3). Gas chromatography and HPLC are the techniques most widely used to meet these analytical demands. Very important are pretreatment of food samples and clean-up procedures. In Slovakia limits for B)a)P in food are: 0.001 mg/kg in smoked meat and fish products; 0.003 mg/kg in paprika, pepper, sausages. Other PAHs (from US EPA 16 PAH) have no limits. This paper describes determination of benzo(a)pyrene in different food samples by gel permeation chromatography and the HPLC method with a fluorescence detector. State Veterinary Institute (SVU) in Dolný Kubín (Slovakia) is authorized for determination of benzo(a)pyrene in all samples, which are imported to Slovakia. Many samples with excessive of benzo(a)pyrene were from Baltic Sea (especially smoked sprats).

Benzo(a)pyrene↗
PubMed1975

Transplacental and direct action of benzo(a)pyrene studied in organ cultures of embryonic lung tissue.

Transplacental effect of benzo(a)pyrene was studied in organ cultures of embryonic lung tissue explanted from mouse donors injected by the carcinogen. Hyperplastic alteration of epithelium, followed by adenomatous changes were seen in embryonic lung tissue cultures from donor mice injected by benzo(a)pyrene. No alteration was seen in control cultures in which the mice were injected by a non-carcinogenic hydrocarbon (pyrene). Besides the blastomogenic action, a growth-promoting effect of the benzo(a)pyrene was observed in the particular organ cultures of the embryonic lung tissue.

Adenoma↗
PubMed2001

[The comparisons of fluorescence quenching between perylene and pyrene].

The fluorescence quenching of perylene and pyrene by dimethyl terephthalate (DMTP) and N,N-dimethylaniline (DMA) have been investigated. The results show that pyrene can form exciplex with DMTP or DMA at room temperature and perylene can only form exciplex with DMA. The fluorescence quenching date is in conformity with the Stern-Volmer equation: F0/F = 1 + KSV[Q] = 1 + Kq.tau 0[Q], the F0/F-[Q] straight lines are drawn. The Stren-Volmer constants and fluorescence quenching rate constants (KSV and Kq) are obtained. The Stern-Volmer quenching constants of pyrene is larger than that of perylene. The differences is due to the molecular structure of perylene which is not a typical large conjugated system and less coplanar configuration than pyrene.

Aniline Compounds↗
PubMed2004

Binding of pyrene to dissolved organic matters: fractionation and characterization.

Based on a modified Leenheer DOM fractionation scheme, fractionation of DOM from the paddy soil was conducted by using XAD-8 resin into hydrophobic bases (HOB), hydrophobic acids(HOA), acid-insoluble matter (AIM), hydrophobic neutrals (HON) and hydrophilic matter (HIM). In total carbon content of DOM, 35.32% were the HIM and only 0.73% the HOB. However, HOA and AIM altogether occupied 53.45%, while the HON fraction represented 10%. The sorption experiments were conducted to determine the sorption capacity of pyrene on unfractionated DOM and its fractions. Elemental analysis, 1H-NMR and FTIR spectra were carried out on unfractionated DOM and its fractions to examine the relationship between the structure of DOM and partition coefficients (K(oc)). The results showed that HON had a greater affinity for binding pyrene than other fractions. While HON was characterized by large long-chain alkylate (aliphatic structure). AIM exhibited relative higher K(oc) values than HOA and HIM, due to much aromatic structure in AIM, while the high content of carboxylic groups of HOA and HIM depressed their binding capacity. This study demonstrated HON is a key subcomponents of DOM in binding of pyrene, in other words, aliphalic structure in DOM play an important role in binding of pyrene.

Environmental Monitoring↗
PubMedDate not supplied

[Microbiological degradation of benz(a)pyrene in soil].

Several microbial clones that could grow on the benz(a)pyrene medium were identified from the soils contaminated with petroleum products. It was shown that benz(a)pyrene could be degraded by the obtained cultures that selectively utilized the carcinogenic molecules of benz(a)pyrene in the presence of other sources of carbohydrate. The authors give recommendations on the biodestruction of benz(a)pyrene and other polycyclic aromatic hydrocarbons under natural conditions in order to improve the oncoecological situation.

Bacteria↗
PubMed2005

[Aging of spiked pyrene in two paddy soils and their particle-size fractions after soil incubation and changes in extractability and bio-availability to earthworm].

Effect of aging on bioavailability and extractability of persistent organic pollutants has recently been paid much attention in environmental studies. This study deals with aging of spiked pyrene, a four-ring polycyclic hydrocarbon, in two paddy soils and their particle-size fractions under laboratory incubation and change in its extractability and bioavailability. The bioavailability of aged pyrene was tested by an assay of exposure to earthworms (Eisenia foetida). The extractability of spiked pyrene was decreased by 15% to 23%, and the bioavailability to earthworm was decreased by 37% to 67% after incubation for 90 d compared to under no incubation. Meanwhile, there was no significant difference in the pyrene extractability between incubation with different size fractions of a single soil. Soil incubation resulted in lower extractability and, thus, lower environmental risk of the organic pollutants after incorporation in paddy soils and their aggregates. The different size fractions of paddy soils may exert different bioavailability when exposure to soil fauna. Thus, content and chemical extractability may not be appropriate index for assessing the potential environmental risk and bioavailability to soil fauna for persistent organic pollutants in paddy soils.

Animals↗
PubMed2006

Ionizing radiation synergistic induction of cyclooxygenase-2 with benzo[a]pyrene diol-epoxide through nuclear factor of activated T cells in mouse epidermal Cl 41 cells.

Carcinogenic effects of ionizing radiation and benzo[a]pyrene-7,8-diol-9,10-epoxide (B[a]PDE), a major metabolite of benzo[a]pyrene (B[a]P), have been well demonstrated both in vitro and in vivo. Two-stage carcinogenesis results indicate that mouse skin is highly susceptible to both ionizing radiation and benzo[a]pyrene-7,8-diol-9,10-epoxide (B[a]PDE), a major metabolite of benzo[a]pyrene (B[a]P). It is believed that signaling pathways leading to the regulation of gene expression play a significant role in the development of skin cancers. The NFAT family of proteins are important transcription factors involved in the regulation of various target genes, such as IL-1 and TNF-alpha, which play key roles in the regulation of inflammation and carcinogenesis. Thus, the effect of ionizing radiation and B[a]PDE on COX-2 induction and NFAT3 activation, and their relationship, was investigated in mouse epidermal Cl 41 cells. We found that B[a]PDE exposure induced a very high level of NFAT activation in mouse epidermal Cl 41 cells. Ionizing radiation exhibited a synergistic effect with B[a]PDE on NFAT activation and COX-2 induction, while ionizing radiation alone had no effect. By stably knocking down NFAT3 protein expression by means of the specific interfering RNA (siRNA) technique, we found that COX-2 induction by B[a]PDE and the synergistic effect of ionizing radiation with B[a]PDE was totally blocked. These results indicate that ionizing radiation acts synergistically with B[a]PDE on COX-2 induction, and the synergism is dependent on the NFAT3 pathway.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1991

[Analysis of polycyclic aromatic hydrocarbons in lipid-containing biological matrices--study of contamination of breast milk by benzo(a)pyrene along transit routes through Tyrol].

41 samples of human milk from the region of Tyrol were investigated with regard to benzo(a)pyrene content. A complicated analytical preparatory method had to be worked out. The percentage recovery of benzo(a)pyrene was 85-90. Analysis was carried out by means of capillary gas chromatography and flame ionization detection or mass spectrometry. The limit of benzo(a)pyrene detection is 0.1-1 microgram/kg (single ion monitoring). None of the investigated samples of milk showed the presence of benzo(a)pyrene.

Air Pollutants↗
PubMed1991

Pyrene fluorescence probing of unsaturated lipids in Phytophthora infestans zoospores.

Pyrene rapidly penetrates into isolated zoospores of phytopathogenic fungus Phytophthora infestans localizing predominantly in lipid bodies. An analysis of steady-state monomer and excimer fluorescence spectra, as well as of vibronic structure has suggested a considerable part of the fluorescent probe to be located in a lipid environment. Pyrene partition into hydrophilic phase was observed at its high concentrations. Catalytic hydrogenation of unsaturated lipids in zoospores in situ reduced excimer production. The kinetics of changes of pyrene excimerization suggest that hydrogenation affects both the surface and the intrinsic lipids of the zoospores. The usefulness of pyrene as a fluorescent probe for unsaturated lipids in membranes and lipid bodies of intact cells, and the possible role of eicosapolyunsaturated fatty acids in induction of immune response in potato plants are discussed.

Binding Sites↗
PubMed1991

Two-site attachment of troponin to pyrene-labeled tropomyosin.

The interaction of troponin (a complex of troponin T, troponin I, and troponin C) with tropomyosin (Tm) was studied using the fluorescence of pyrene-labeled Tm. Fluorescence titrations showed that an increase in salt concentration not only decreased the binding constant of troponin to Tm but also decreased the magnitude of the total pyrene fluorescence change. This indicates that the interaction of the part of troponin (TnT2) with the middle of Tm near Cys-190 is weakened at high ionic strength, while the other part (TnT1) maintains its binding with the C-terminal region of Tm. The temperature dependence of the pyrene excimer fluorescence of Tm showed that troponin stabilized the whole Tm molecule with much less effect on the stability of the middle region where the TnT2 binds. TnT1, the N-terminal chymotryptic fragment of troponin T (TnT), stabilized Tm in a similar manner to troponin by inhibiting dissociation of Tm chains in the main unfolding transition. Thus, these data indicate a loose interaction of the TnT2 part of troponin with the region of Tm near Cys-190 and a tight interaction of the TnT1 part with the C-terminal region of Tm. TnT alone interacted more strongly with Tm near Cys-190 than when in the troponin complex. This was indicated by the following observations in the Tm.TnT complex compared to the Tm-troponin complex: (i) a more hydrophobic environment of pyrene at Cys-190 of Tm; (ii) stabilization against the local unfolding of Tm near Cys-190; (iii) more fluorescence resonance energy transfer between Tm and TnT. These studies indicate a loose and flexible interaction of troponin with the middle region of Tm which may be important in Ca2+ regulation by troponin.Tm.

Animals↗
PubMed1990

[Evaluation of the inducing and autoinducing properties of pyrene, fluoranthene and benz(a)anthracene].

In the present study we have examined the effect of treatment with benz(a)-anthracene (BaA), pyrene (P) and fluoranthene (Fl) on the total liver microsomal content of cytochrome P-450 and elimination of these PAH from blood in rats. The experiment was carried out on adult male rats Wistar breed. Oil solution of inducers: benz(a)anthracene, pyrene and fluoranthene in dose 20 mg/kg were administered individually one or threefold by gavage. 24 h after a single dose of PAH cytochrome P-450 content in rat liver determined by the method of Omura and Sato was the same as in control group. When PAH were administered p.o. for three consecutive days in the fourth day of experiment cytochrome P-450 content was increased from about 0.68 nM/mg protein to about 1.2 nM/mg. Since the increase of cytochrome P-450 may influence on elimination of xenobiotics we have determined affect PAH on their blood level after i.v. administration. One hour after BaA administration and two hours after Fl and P blood samples were collected. Concentration of PAH in blood was determined by gas-liquid chromatography. Pretreatment of rats with BaA decreased elimination of Fl, P, BaA from blood in comparison to the control rats. It indicated on the self-inducing effect of BaA on its own metabolism and inducing effect of metabolism other PAH. Pretreatment of rats with pyrene decreased elimination of BaA. It seemed that pyrene inhibited the oxidation of BaA in rat liver microsomes.

Animals↗
PubMedDate not supplied

Alteration in hepatic nuclear RNA polymerase activity following benzo[a]pyrene administration in rat.

Benzo[a]pyrene was administered intraperitoneally to male Wistar rats as a single dose of 20 mg.kg-1 body weight. Two hours after its administration, livers were excised and the enzyme RNA polymerase was solubilized from purified nuclei. The enzyme was resolved into three forms, polymerase I, II and III by partial purification on DEAE-Sephadex A-25 column. All the three forms of nuclear RNA polymerase were inhibited in response to administration of benzo[a]pyrene. This was evident in terms of total yield as well as specific activity of each enzyme. The inhibition of nuclear transcription following administration of benzo[a]pyrene as observed previously (1) along with the present results on the enzyme inhibition clearly suggest that benzo[a]pyrene acts on both the major components of transcription machinery i.e. the template chromatin and the enzyme RNA polymerases.

Animals↗