- Reductions of nitro and 9-oxo groups of environmental nitrofluorenes by the rat mammary gland in vitro
-
Nitrofluorenes and C-9-oxidized nitrofluorenes are widespread environmental genotoxins which may be relevant for breast cancer on the basis of their carcinogenicities, particularly of 2,7-dinitrofluorene (2,7-diNF), for the rat mammary gland. Since their metabolism to active carcinogens may involve nitroreduction, this study examined the reduction of 2-nitrofluorene (2-NF) and 2,7-diNF and their 9-oxo- and 9-hydroxy (OH) derivatives by the rat mammary gland. Cytosolic fractions catalyze NADH- and NADPH-dependent reductions of the 2-nitro and 9-oxo to the respective 2-amino and 9-OH compounds at rates 4- and ≥10-fold greater than those with microsomes. Rates of amine formation catalyzed by cytosol from 2,7-diNF are greater than the rate from 2-NF and increase for C-9-oxidized derivatives: 9-oxo-2-NF >> 9-OH-2-NF > 2-NF and 9-OH-2,7-diNF 9-oxo-2,7-diNF >> 2,7-diNF. Nitroreduction is inhibited by O2 or allopurinol (20 μM), dicoumarol (100 μM), and rutin (50 μM). 9-Oxoreduction is inhibited by rutin, dicoumarol, and indomethacin (100 μM), but not by O2 or allopurinol. Pyrazole or menadione does not inhibit nitro or 9-oxoreduction. Xanthine, hypoxanthine, 2-hydroxypyrimidine, and N'-methylnicotinamide support cytosol-catalyzed nitro, but not 9-oxo, reduction. The data suggest that the nitroreduction is catalyzed largely by a xanthine oxidase and partially by a diaphorase and 9-oxoreduction by a carbonyl reductase. The extents of the nitro and carbonyl reductions of the nitrofluorenes may determine their reactivities with DNA, and thus genotoxicities for the mammary gland.
- Ritter,Decker,Malejka-Giganti
-
p. 793 - 800
(2007/10/03)
-
- Preneoplastic lesions, DNA adduct formation and mutagenicity of 5-, 7- and 9 -hydroxy-2-nitrofluorene, metabolites of the air pollutant 2-nitrofluorene
-
The metabolites of 2-nitrofluorene (NF), 5-, 7- and 9-OH-2-nitrofluorene (OH-NF) were compared for their genotoxicity. Seventy-two hours after intraperitoneal administration of these substances individually to rats (100 mg/kg body wt.), DNA adducts in liver tissue were analyzed with 32P-TLC and 32P-HPLC. An in vivo liver model was used to test the initiating capacity of the said substances for the formation of preneoplastic lesions. 5-OH-NF showed low capacity to induce DNA adduct formation and low potential as initiator to induce preneoplastic lesions-foci/nodules in the liver of rats. Both 7- and 9-OH-NF induced DNA adducts and preneoplastic liver lesions but with smaller quantities compared to NF. It seems that 7- and 9-OH-NF can not be considered as detoxification products of NF. In general, the initiating capacity of these substances for the formation of preneoplastic lesions has a good correlation with their potency to form DNA adducts.
- Cui, Xian-Shu,Bergman, Jan,Moeller, Lennart
-
p. 147 - 155
(2007/10/03)
-
- Regiospecific Syntheses of All Isomeric Nitrofluorenones and Nitrofluorenes by Transition Metal Catalyzed Cross-Coupling Reactions
-
Regiospecific efficient syntheses of 1-, 2-, 3-, and 4-nitrofluorenones 8 and the corresponding nitrofluorenes 10 by palladium(0)-catalyzed cross-coupling reactions of aryl boronic acids 1 with bromonitrotoluenes 2 and bromonitrobenzene 3 are described.
- Iihama, T.,Fu, J.-m.,Bourguignon, M.,Snieckus, V.
-
p. 184 - 188
(2007/10/02)
-