Search results for "ANTHRACENE"
showing 10 items of 171 documents
Photoinduced toxicity of retene to Daphnia magna under enhanced UV-B radiation.
2001
Abstract The effects of UV radiation on the acute toxicity of retene (7-isopropyl-1-methylphenanthrene) to Daphnia magna Straus were studied. Dehydroabietic acid (DHAA) from which retene is formed in the vicinity of pulp and paper industry was also studied. Pyrene, anthracene, and phenanthrene were used as model PAH compounds. The time taken for immobilization (ET50) was monitored under biologically effective UV-B dose rates of 240, 365, 565, and 650 mW m−2 (UV-A and visible light also present). Median effective concentrations (EC50) were determined after a 15-min UV exposure (565 mW m−2) followed by 24 h in the dark. Retene ( 10–320 μg l −1 ) was not acutely toxic in the dark. The inductio…
Solid-Phase Synthesis of Peptide Libraries Combining α-Amino Acids with Inorganic and Organic Chromophores
2009
The synthesis of two series of peptidic chains composed of bis(terpyridine)ruthenium(II) acceptor units and organic chromophores (coumarin, naphthalene, anthracene, fluorene) by stepwise solid-phase peptide synthesis (SPPS) techniques is described. The first series of dyads comprises directly amide linked chromophores, while the second one possesses a glycine spacer between the two chromophores. All dyads were studied by UV/Vis and NMR spectroscopy, steady-state luminescence, luminescence decay and electrochemistry, as well as by DFT calculations. The results of these studies indicate weak electronic coupling of the chromophores in the ground state. Absorption spectra of all dyads are domin…
Ligand-binding assays with OBPs and CSPs
2020
Assessing the ligand-binding properties of OBPs and CSPs is essential for understanding their physiological function. It also provides basic information when these proteins are used as biosensing elements for instrumental measurement of odors. Although different approaches have been applied in the past to evaluate the affinity of receptors and soluble binding proteins to their ligands, using a fluorescent reporter represents the method of choice for OBPs and CSPs. It offers the advantages of working at the equilibrium, being simple, fast and inexpensive, without requiring the use of radioactive tracers. However, as an indirect method, the fluorescence competitive binding approach presents d…
On the Use of Metal Purine Derivatives (M=Ir, Rh) for the Selective Labeling of Nucleosides and Nucleotides
2014
The reactions of neutral or cationic IrIII and RhIII derivatives of phenyl purine nucleobases with unsymmetrical alkynes produce new metallacycles in a predictable manner, which allows for the incorporation of either photoactive (anthracene or pyrene) or electroactive (ferrocene) labels in the nucleotide or nucleoside moiety. The reported methodology (metalation of the purine derivative and subsequent marker insertion) could be used for the postfunctionalization and unambiguous labeling of oligonucleotides.
K-region oxides and imines derived from alkylated benz[α]anthracene congeners: synthesis, stability in aqueous media and mutagenicity
1994
The K-region oxides and imines of benz[a]anthracene, 1-methylbenz[a]anthracene, 7-methylbenz[a]anthracene, 7-ethylbenz[a]anthracene and 7,12-dimethylbenz[a]anthracene were synthesized and characterized (melting point, 1H-NMR and electron impact mass spectra, elemental analysis, IR spectroscopy). All 10 compounds showed high mutagenic activity in Salmonella typhimurium (reversion of his- strains TA97, TA98, TA100 and TA104). The arene imines were more potent than the corresponding arene oxides. Alkyl substitutions strongly influenced the activities. Furthermore, all compounds were more active when exposure took place in the absence of inorganic ions than when KCl (125 mM) was present. The in…
Prevention of benzo(a)pyrene-induced mutagenicity by homogeneous epoxide hydratase
1976
Benzo(a)pyrene and benz(a)anthrancene which, in contrast to the K-region epoxides benzo(a)pyrene 4,5-oxide and benz(a)anthracene 5,6-oxide, are not mutagenic to Salmonella typhimurium TA 1537 in the absence of mammalian enzyme preparations, were activated by liver microsomes from C3H mice, which had not received any pretreatment, to mutagens reverting this tester strain to histidine prototrophy. Addition of epoxide hydratase inhibitors greatly increased this mutagenicity and addition of pure epoxide hydratase reduced it by more than 95% down to the range of spontaneous mutations as observed in absence of any added mutagen. This demonstrates that the metabolic pathway responsible for the mut…
Strong influence of the exposure medium on mutagenicity in the Ames test: 7-methylbenz[a]anthracene-5,6-oxide.
1991
We have previously shown that the activity of the ionized mutagen, 1-hydroxmethylpyrene sulphate, is strongly enhanced in Salmonella typhimurium TA98, when KCl is present in the exposure medium (50-fold at a concentration of 125 mM KCl) and that the halogen ion is responsible for this effect. Here we show that KCl has the opposite effect on the activity of the lipophilic mutagen, 7-methylbenz[a]anthracene-5,6-oxide, (10-fold decrease at a concentration of 125 mM) and that K+ accounts for this influence. Many other solutes also decreased the mutagenicity of 7-methylbenz[a]anthracene-5,6-oxide, but to a smaller extent than the K+ salts. The stability of 7-methylbenz[a]anthracene-5,6-oxide did…
Evaluation of the SOS/umu-test post-treatment assay for the detection of genotoxic activities of pure compounds and complex environmental mixtures.
2000
This study presents an evaluation of the SOS/umu-test after introducing an additional dilution and incubation in the post-treatment assay. This treatment reduces the influence of coloured test compounds that otherwise affect the colorimetric determination of the beta-galactosidase activity and the bacterial growth measurement during the testing of complex environmental samples. The post-treatment assay significantly increased the beta-galactosidase activity and consequently the enzyme induction ratios at higher doses of model genotoxins 4-nitroquinoline-N-oxide, N-methyl-N'-nitro-N-nitrosoguanidine, 2-aminoanthracene, benzo(a)pyrene with low or no effect on the sensitivity of the test itsel…
Synthesis, Absolute Configuration, and Bacterial Mutagenicity of the 8 Stereoisomeric Vicinal Diol Epoxides at the Terminal Benzo Ring of Carcinogeni…
2011
The synthesis of the 8 possible stereoisomeric diol epoxides (DEs) at the terminal benzo ring of carcinogenic dibenz[a,h]anthracene (DBA) is reported. trans-3,4-Dihydroxy-3,4-dihydro-DBA (1) afforded the 4 bay region DEs: the enantiomeric pairs of the anti diastereomers (+)-3/(-)-3 and of the syn diastereomers (-)-4/(+)-4, respectively. trans-1,2-Dihydroxy-1,2-dihydro-DBA (2) served as precursor of the 4 reverse DEs: the enantiomeric pairs of the anti diastereomers (+)-5/(-)-5 and of the syn diastereomers (-)-6/(+)-6, respectively. The transformation of the olefinic double bond in the enantiomeric trans-dihydrodiols to epoxides was achieved by either (i) oxidation with m-chloroperoxybenzoic…
Post-Transcriptional Regulation of Human Inducible Nitric-Oxide Synthase Expression by the Jun N-terminal Kinase
2007
Human inducible nitric-oxide synthase (iNOS) expression is regulated both at transcriptional and post-transcriptional levels. In the present study, the effect of Jun N-terminal kinase (JNK) on human iNOS expression was investigated. In A549/8 human alveolar epithelial cells, both the inhibition of JNK by a pharmacological inhibitor anthra[1,9-cd]pyrazol-6(2H)-one1,9-pyrazoloanthrone (SP600125) and small interfering RNA (siRNA)-mediated down-regulation of JNK led to a reduction of iNOS mRNA and protein expression. iNOS promoter activity was not affected by these treatments. Hence, JNK seems to regulate iNOS expression through post-transcriptional mechanisms by stabilizing iNOS mRNA. Our labo…