Search results for "Pyrene"
showing 10 items of 260 documents
Fjord-region diol-epoxides of benzo[c]chrysene are potent inducers of micronuclei in murine bone marrow
1994
Abstract Vicinal diol-epoxides are the best established carcinogenic metabolites of polycyclic aromatic hydrocarbons. Numerous studies have demonstrated their high genotoxic activity in various in vitro test systems. However, in vivo mutagenicity data are not available. The fjor-region diol-epoxides of benzo[ c ]chrysene combine high mutagenic activity in vitro with hydrolytic stability. They were tested for the induction of micronuclei in the bone marrow following intraperitoneal administration to NMRI mice. The anti diasteromer of the diol-epixode enhanced the frequency of micronucleated polycrhomatic erythrocytes strongly (7–19-fold above the value in untreated controls) over a very wide…
Regiospecific oxidation of polycyclic aromatic dihydrodiols by rat liver dihydrodiol dehydrogenase
1991
Rat liver dihydrodiol dehydrogenase (DDH, E.C. 1.3.1.20) has recently been shown to oxidize the highly carcinogenic benz[a]anthracene-3,4- dihydrodiol in an NADP(+)-dependent reaction to its corresponding catechol. The present study is a systematic investigation of the substrate specificity of the purified enzyme towards synthetic trans-dihydrodiol metabolites of phenanthrene, benz[a]anthracene, chrysene, dibenz[a, h]anthracene and benzo[a]pyrene. DDH exhibited a remarkable regiospecificity of enzymatic catalysis with regard to the site of the dihydrodiol moiety of the parent hydrocarbon. M-region- and, with lower efficiency, bay-region dihydrodiols were found to be good substrates of the e…
Protective Effects of Fruits and Vegetables against In Vivo Clastogenicity of Cyclophosphamide or Benzo[a]pyrene in Mice
1998
Seven fruits and 10 vegetables commonly consumed in Germany were investigated for their anticlastogenic potencies against cyclophosphamide (CP) and benzo[a]pyrene (BaP) in the in vivo mouse bone marrow micronucleus assay. We detected protective effects in 76.5% and 70.6% of the samples, respectively, and more or less distinct quantitative differences between the various plant materials and the two clastogens investigated. With respect to CP, moderate activities were exerted by sweet cherries, strawberries, cucumber, radish and tomatoes, average activities by bananas, oranges, peaches, asparagus and red beets and strong activities by yellow red peppers and especially spinach. Apples (cultiva…
A Method for the Cryopreservation of Liver Parenchymal Cells for Studies of Xenobiotics
1993
Abstract An optimized computer-controlled freezing protocol for the cryopreservation of rat liver parenchymal cells was developed. The best survival rates were obtained when a slow cooling rate was used and when the supercooling was interrupted with a shock cooling to initiate ice nucleation. Ten percent dimethyl sulfoxide was added and removed gradually for best results. Thawed rat liver parenchymal cells had a viability, as judged by trypan blue exclusion, of 69% (SD = 6) versus 82% (SD = 7) for freshly isolated cells. The content and activities of the xenobiotic metabolizing enzymes, cytochrome P450. UDP-glucuronosyl transferase, and microsomal and cytosolic epoxide hydrolase, were not a…
Induction of rat hepatic epoxide hydratase by dietary antioxidants
1979
Abstract Supplementation of rat diet with butylated hydroxytoluene (BHT), butylated hydroxyanisole, or ethoxyquin resulted in increased liver epoxide hydratase activity. The increase was obvious at 0.1% and amounted to 200–400% at 0.5%. Increased activity was accompanied by increased proportion of the epoxide hydratase band in SDS polyacrylamide gels, indicating induction of the enzyme. Ethoxycoumarin deethylase activity and cytochrome b5 concentrations were moderately elevated while cytochrome P-450 concentrations and aryl hydrocarbon hydroxylase activity remained at control levels. Preferential inhibition of monooxygenase activity by metyrapone and not 7,8-benzoflavone, as well as increas…
Ethoxyquin feeding to rats increases liver microsome-catalyzed formation of benzo(a)pyrene diol epoxide--DNA adduct.
1978
Abstract The ability of rat liver microsomes to catalyze the formation of benzo(a)pyrene 7,8-diol-9,10-epoxide — DNA nucleoside adduct was increased threefold by feeding 0.5% ethoxyquin to the animals. Microsomal epoxide hydratase activity was enhanced i parallel by a factor of 3 while aryl hydrocarbon hydroxylase activity was not induced. Liver microsomes from rat pretreated with 3-methylcholanthrene produced an increased proportion of diol epoxide — DNA adduct when ethoxyquin had been fed to the animals. The main chromatographic peak formed by microsomes from 3-methylcholanthrene treated rats which contains DNA adducts of secondary benzo(a)pyrene phenol metabolites is reduced when the ani…
Effect of dietary antioxidants on benzo[a]pyrene metabolism in rat liver microsomes
1983
Feeding of rats with 1% ethoxyquin (EQ) and butylated hydroxytoluene (BHT) but not butylated hydroxyanisole (BHA) increases the formation rate of benzo[a]pyrene (BP)-4,5-dihydrodiol from BP in hepatic microsomes. The production of other BP-dihydrodiols and of BP phenols is decreased after treatment with EQ, BHT and BHA. EQ and BHT are more effective than BHA in inducing epoxide hydrolase (EH) activity towards styrene oxide as the substrate.
Inhibition of clastogenicity of benzo[a]pyrene and of its trans-7,8-dihydrodiol in mice in vivo by fruits, vegetables, and flavonoids.
2003
In the in vivo mouse bone marrow micronucleus assay, homogenates of spinach, artichoke, peaches, and blue grapes as well as commercial concentrates of these vegetables and fruits reduced induction of micronuclei by benzo[a]pyrene (BaP) by 43-50%. Concentrates of strawberries (31% reduction) and of cauliflower (20% reduction) were less potent. Inhibition of genotoxicity by spinach and peaches was not caused by any delay in maturation of micronucleated erythrocytes as shown by experiments with sampling times of 24, 48, and 72 h after dosing of BaP. Pre-treatment of the mice with spinach 48, 24, and 12h before application of BaP resulted in a 44% reduction of micronuclei while peaches generate…
Enzymic control of irreversible binding of metabolically activated benzo(a)pyrene in perfused rat liver by monooxygenase activity.
1977
Addition of [3H]-benzo(a)pyrene to the perfusion medium of isolated rat livers results in irreversible binding of radioactivity to DNA, RNA and protein. Binding to DNA accounted for about 0.1% of the total radioactivity which was bound in livers from animals treated with oil or saline and was increased by a factor of 3–5 after pretreatment of the animals with β-naphthoflavone or with phenobarbital. When the inhibitiors of monooygenase activity, α-naphthoflavone or metyrapone, were present in the perfusion medium, irreversible binding was reduced in livers from both β-naphthoflavone- and phenobarbital-pretreated animals, irrespective of the inhibitor used.
Endogenous role of epoxide-hydratase. Development of a steroid epoxide-hydratase assay and properties of the enzyme.
1979
A highly sensitive and rapid radiometric assay for the determination of specific epoxide hydratase activity with a steroid epoxide (16α, 17α-epoxy-1,3,5(10)-estratrien-3-ol, ‘estroxide’) has been developed. The unreacted substrate was separated from the product 1,3,5(10)-estratrien-3,16β,17α-triol by extraction into light petroleum. The product was then extracted into ethyl acetate and measured by scintillation spectrometry. Radiochromatography established that after subtraction of the blank the entire radioactivity measured in the ethyl acetate phase resulted from the product 1,3,5(10)-estratrien-3,16,17-triol, whilst high performance liquid chromatography with the four possible isomers of…