Search results for "Pyrene"
showing 10 items of 260 documents
(E)-7-(Pyren-1-yl)hept-6-enoic acid
2010
The title compound, C23H20O2, is a precursor of a pyrene-based supramolecular element for non-covalent attachment to a carbon nanotube. The asymmetric unit contains three independent molecules. The carboxylic acid group in each of these molecules serves as an intermolecular hydrogen-bond donor and acceptor, generating the commonly observed double O—H...O hydrogen-bond motif in an eight-membered ring. Weaker C—H...O, π–π [centroid–centroid distance = 3.968 (4) Å] and C—H...π interactions are also found in the crystal structure.
Synthesis of Tripyreno[2,3,4-abc: 2,3,4-ghi: 2,3,4-mno][18]annulenes
2000
The title compounds were prepared in a multi-step synthesis in which primarily the pyrene building blocks were formed (1,2 11a,b). The final reaction step 11a,b 12a,b consisted of a threefold trans selective cyclocondensation process that generated the central 18-membered ring. Hexyloxy or dodecyloxy sidechains attached on the periphery led to the formation of liquid crystalline phases.
Benzo[a]pyrene represses DNA repair through altered E2F1/E2F4 function marking an early event in DNA damage-induced cellular senescence
2020
AbstractTranscriptional regulation of DNA repair is of outmost importance for the restoration of DNA integrity upon genotoxic stress. Here we report that the potent environmental carcinogen benzo[a]pyrene (B[a]P) activates a cellular DNA damage response resulting in transcriptional repression of mismatch repair (MMR) genes (MSH2, MSH6, EXO1) and of RAD51, the central homologous recombination repair (HR) component, ultimately leading to downregulation of MMR and HR. B[a]P-induced gene repression is caused by abrogated E2F1 signalling. This occurs through proteasomal degradation of E2F1 in G2-arrested cells and downregulation of E2F1 mRNA expression in G1-arrested cells. Repression of E2F1-me…
Applications of stable V79-derived cell lines expressing rat cytochromes P4501A1, 1A2, and 2B1.
1992
1. Chinese hamster V79-derived cell lines, stably expressing cytochromes P4501A1, 1A2, and 2B1 activities, were constructed by genetic engineering in continuation of our work to establish a battery of V79 derived cell lines designed to study the metabolism of xenobiotics. 2. Cell lines XEM1 and XEM2, expressing cytochrome P4501A1, were capable of the O-dealkylation of 7-ethoxycoumarin and the hydroxylation of benzo[a]pyrene. 3. Cell lines XEMd.MZ and XEMd.NH, expressing P4501A2, were shown to hydroxylate 17 beta-estradiol and 2-aminofluorene. 4. Cell line SD1, expressing cytochrome P4502B1, was able to hydroxylate testosterone stereo- and regio-specifically at the 16 alpha and 16 beta posit…
NADPH-cytochrome P-450 reductase: Preferential inhibition by ellipticine and other type II compounds having little effect on NADPH-cytochrome c reduc…
1980
Abstract Ellipticine (5,11-dimethyl-[6H]-pyrido[4,3b]carbazole) binds with an affinity greater than most other compounds known to interact with P-450. Control and 3-methylcholanthrene-induced aryl hydrocarbon (benzo[ a ]pyrene) hydroxylase (EC 1.14.14.2) and acetanilide 4-hydroxylase and control and phenobarbital-induced ethylmorphine N -demethylase activities are all markedly inhibited by ellipticine to about the same extent. Ellipticine and other Type II compounds (metyrapone, octylamine-1, pyridine and aniline) preferentially inhibit NADPH-cytochrome P-450 reductase activity, while affecting NADPH-cytochrome c reductase activity very little. Butanol-1, a compound having pure Reverse Type…
The autoradiographic test for unscheduled DNA synthesis: a sensitive assay for the detection of DNA repair in the HepG2 cell line
2004
International audience; We assessed the DNA-repair capacity of HepG2 cells, which were derived from a human hepatoma, by the unscheduled DNA synthesis assay, using the autoradiography protocol (UDS-AR). We evaluated DNA repair following exposure to direct mutagens (4-nitroquinoline-N-oxide (4-NQO), methyl methanesulfonate (MMS)), to mutagens requiring metabolic activation (benzo[a]pyrene (B[a]P), 2-acetylaminofluorene (2-AAF), N-dimethylnitrosoamine (NDMA)) or to structurally related non-mutagens such as pyrene and 4-acetylaminofluorene (4-AAF). All positive compounds tested induced UDS in HepG2 cells. With 4-NQO and MMS, a concentration-dependent increase in net nuclear grains per cell was…
A microplate version of the DNA-synthesis inhibition test for rapid detection of DNA-alteration potentials.
1990
A microplate version of the DNA-synthesis inhibition test (DIT) for fast detection of DNA-alteration potentials has been developed. The DIT is based on the concept that DNA damage causes inhibition of DNA synthesis that becomes detectable some time after replicating cells have been in contact with genotoxic agents. In this test procedure human tissue culture cells (HeLa S3), prelabeled with [14C]thymidine, arfe exposed for 90 min to the substances in question. After the cells are rinsed, they are allowed to recover for 2 1/2 h in fresh culture medium, thereby unspecific interactions interfering with DNA replication are practically eliminated. Next, [3H]thymidine is added for 30 min, and the…
Photoinduced DNA damage efficiency and cytotoxicity of novel viologen linked pyrene conjugates.
2010
Novel viologen linked pyrene conjugates permeate cells efficiently and exhibit spacer length dependent DNA damage and cytotoxicity upon photoexcitation.
Biodiversity within the subfamily Alyssinae (Hymenoptera, Braconidae) in the Natural Park Peñas de Aya (Spain)
2011
Biodiversity within the subfamily Alyssinae (Hymenoptera, Braconidae) in the Natural Park Peñas de Aya (Spain). The study of parasitoid Hymenoptera is of significance for the assessment of diversity in a given area because of their role in the regulation of insects populations. The present work analyses diversity within Alysiinae (Hymenoptera, Braconidae) in the Forested Estate of Artikutza, located in the Natural Park Peñas de Aya, western Pyrenees, Spain. Collection of specimens was spread over two years and was carried out in two different habitats: mixed forest and beech forest. A total of 2,270 specimens, belonging to 22 separate genera, were captured. Subsequently, alpha, beta and gam…
Ligand-Based Charge-Transfer Luminescence in Ionic Cyclometalated Iridium(III) Complexes Bearing a Pyrene-Functionalized Bipyridine Ligand: A Joint T…
2012
Two new heteroleptic iridium(III) complexes [Ir(ppy)(2)(pyr(2)bpy)][PF(6)] ([1a][PF(6)]) and [Ir(dfppy)(2)(pyr(2)bpy)][PF(6)] ([2a][PF(6)]), where Hppy = 2-phenylpyridine, Hdfppy = 2-(3,5-difluorophenyl)pyridine, and pyr(2)bpy = 5,5'-bis(pyren-1-yl)-2,2'-bipyridine, have been synthesized and fully characterized. The single-crystal structures of pyr(2)bpy and the complexes 4{[1a][PF(6)]}·2CH(2)Cl(2)·9H(2)O and [2a][PF(6)]·0.25CH(2)Cl(2)·H(2)O have been determined. The effect of the pyrene substituents on the electronic properties is investigated through a comprehensive photophysical and theoretical study on the two complexes in comparison to reference complexes without substituents on the an…