benzofurans and fluorene

Fluorene and its three heteroatomic analogs, dibenzofuran, dibenzothiophene, and carbazole, are environmental contaminants in areas impacted by spills of creosote. In addition, dibenzofuran has been used as an insecticide, and it is formed from the photolysis of chlorinated biphenyl ethers. Many biodegradation studies of dibenzofuran have considered it as a model for chlorinated dibenzofurans, which are of greater environmental concern. This paper reviews the bacterial degradation of fluorene and its analogs. These compounds are susceptible to three different modes of initial oxidation: (i) the naphthalene-like attack, in which one of the aromatic rings is oxidized to a dihydrodiol; (ii) an angular dioxygenase attack, in which the carbon bonded to the methylene group in fluorene or to the heteroatoms in the analogs, and the adjacent carbon in the aromatic ring are both oxidized; and (iii) the five-membered ring attack, in which the methylene carbon atom in fluorene or the sulfur atom in dibenzothiophene is oxidized. The metabolites, enzymology, and genetics of these transformation are summarized. Literature data are presented, indicating that the electronegativity of the atom connecting the two aromatic rings influences the attack of the angular dioxygenase. In dibenzofuran and carbazole, the connecting atoms, O and N respectively, have high electronegativities, and these compounds serve as substrates for angular dioxygenases. In contrast, the connecting atoms in dibenzothiophene and fluorene, S and C respectively, have lower electronegativities, and these atoms must be oxidized before the angular dioxygenases attack these compounds.

Topics: Bacteria; Benzofurans; Biodegradation, Environmental; Carbazoles; Fluorenes; Thiophenes

We carried out molecular orbital theory calculations for the homogeneous gas-phase formation of dibenzofuran from phenanthrene, fluorene, 9-methylfluorene and 9-fluorenone. Dibenzofuran will be formed if ∙OH adds to C8a, and the order of reactivity follows as 9-fluorenone > 9-methylfluorene > fluorene > phenanthrene. The oxidations initiated by ClO∙ are more favorable processes, considering that the standard reaction Gibbs energies are at least 21.63 kcal/mol lower than those of the equivalent reactions initiated by ∙OH. The adding of ∙OH and then O2 to phenanthrene is a more favorable route than adding ∙OH to C8a of phenanthrene, when considering the greater reaction extent. The reaction channel from fluorene and O2 to 9-fluorenone and H2O seems very important, not only because it contains only three elementary reactions, but because the standard reaction Gibbs energies are lower than -80.07 kcal/mol.

Topics: Benzofurans; Fluorenes; Gases; Hydroxyl Radical; Oxidation-Reduction; Phenanthrenes; Quantum Theory; Thermodynamics

A combination of multireference CASSCF/CASPT2 and time-dependent DFT (TD-B3P86) theoretical treatments was employed to test their predictions against recently proposed assignments of the vacuum-UV spectra of fluorene and its three heteroanalogues-dibenzofuran, carbazole, and dibenzothiophene-up to the ionization threshold. For the low-lying transitions, the theoretically based assignments are generally not problematic because of the well-resolved bands, although, even in this region, the two methods yield some opposing predictions. Further on toward the vacuum region, the assignments prove increasingly challenging because of predicted crowding of transitions, many of which exhibit significant intensity. Some of the transitions in this region and beyond-toward the ionization thresholds-are thus necessarily assigned only tentatively. Overall, the two methods are frequently found to complement each other well, and equivalent transitions usually appear as bracketed from the high- (CASPT2) and low- (TD-B3P86) energy sides.

Topics: Benzofurans; Carbazoles; Electrons; Fluorenes; Quantum Theory; Thiophenes; Time Factors

Decay kinetics resulting from the application of UV and UV/H(2)O(2) to the polycyclic aromatic hydrocarbons (PAHs) fluorene, dibenzofuran and dibenzothiophene was studied. Batch experiments were conducted with both low-pressure monochromatic (253.7nm) and medium pressure polychromatic (200-300nm) UV sources alone or in the presence of up to 25mg/L hydrogen peroxide, in a quasi-collimated beam apparatus. Degradation of all three PAHs, by both UV and UV/H(2)O(2), exhibited pseudo-first-order reaction kinetics and low quantum yields ranging from 1.4x10(-3) to 1.8x10(-2)mol/E using both UV lamps. Toxicity testing using a bioluminesence inhibition bioassay was correlated to the decay in concentration of the PAHs as analyzed analytically using HPLC. Results demonstrated that treatment efficacy of oxidative PAH degradation measured by following the decay of the target compound is best complemented by also evaluating the toxicity of the treated water due to byproduct formation concerns.

Topics: Aliivibrio fischeri; Benzofurans; Carcinogens; Chromatography, High Pressure Liquid; Fluorenes; Hydrogen Peroxide; Kinetics; Luminescent Measurements; Photolysis; Polycyclic Aromatic Hydrocarbons; Thiophenes; Ultraviolet Rays; Water Pollutants, Chemical

The synthesis, photophysical characterization, and determination of singlet oxygen quantum yields (Phi(Delta)) for a class of fluorene derivatives with potential application in two-photon photodynamic therapy (PDT) is reported. It has been demonstrated that these compounds possess the ability to generate singlet oxygen (1O2) upon excitation. A photochemical method, using 1,3-diphenylisobenzofuran (DPBF) as 1O2 chemical quencher, was employed to determine the singlet oxygen quantum yields (Phi(Delta)) of the fluorene-based photosensitizers in ethanol. Phi(Delta) values ranged from 0.35 to 0.75. These derivatives may have potential application as two-photon photosensitizers when pumped via two-photon excitation in the near-IR spectral region.

Topics: Benzofurans; Ethanol; Fluorenes; Molecular Structure; Oxidants; Photochemotherapy; Photosensitizing Agents; Quantum Theory; Singlet Oxygen; Solvents; Spectrophotometry

The quantum yield, Phi(Delta), of singlet oxygen generation under two-photon excitation has been determined for a fluorene derivative. A photochemical method was developed using 1,3-diphenylisobenzofuran (DPBF), a chemical quencher of 1O2, and 2-(9,9-didecyl-7-nitrofluoren-2-yl)benzothiazole (1) as a two-photon photosensitizer (PS). The photochemical kinetics of the quencher was measured by two different fluorescence methods. Fluorene 1 exhibited relatively high singlet oxygen quantum yield, Phi(Delta) approximately 0.4 +/- 0.1, and had a two-photon absorption cross-section of 28 +/- 5 GM. Thus, 1 may have potential for use as a two-photon PS in the near-IR spectral region for biomedical applications.

Topics: Benzofurans; Fluorenes; Kinetics; Molecular Structure; Photochemistry; Photons; Photosensitizing Agents; Quantum Theory; Singlet Oxygen; Spectrometry, Fluorescence

The dibenzofuran (DF)-utilizing bacterium strain YY-1 was newly isolated from soil. The isolate was identified as Janibacter sp. with respect to its 16S rDNA sequence and fatty acid profiles, as well as various physiological characteristics. In addition to DF, strain YY-1 could grow on fluorene and dibenzothiophene as sole sources of carbon and energy. It was also able to cometabolize a variety of polycyclic aromatic hydrocarbons including dibenzo- p-dioxin, phenanthrene, and anthracene. The major metabolites formed from DF, biphenyl, dibenzothiophene, and naphthalene were identified by using gas chromatography-mass spectrometry as 2,3,2'-trihydroxybiphenyl, biphenyl-dihydrodiol, dibenzothiophene 5-oxide, and coumarin, respectively. These results indicate that strain YY-1 can catalyze angular dioxygenation, lateral dioxygenation, and sulfoxidation.

Topics: Actinomycetales; Benzofurans; Fluorenes; Phylogeny; Polycyclic Aromatic Hydrocarbons; Thiophenes

Reverse transcription-PCR of the dbfA1A2, dbfBC, and pht genes, encoding oxygenase component of multicomponent dioxygenase, meta cleavage enzyme and hydrolase, and phthalate-degrading enzymes, respectively, revealed their role in the aromatic compound degradation by Terrabacter sp. strain DBF63. The specific expression in strain DBF63 cells grown on dibenzofuran (the model compound of dioxin; DF) and/or fluorene (FN) indicated that the DbfA1A2 and DbfBC catalyze the conversion of DF to salicylate, and that the DbfA1A2 and Pht enzymes are involved in FN degradation. Pulsed-field gel electrophoresis analyses revealed that the dbfA1A2 cistron and pht operon were located on the two linear plasmids, pDBF1 (160 kb) and pDBF2 (190 kb), while dbfBC genes were located on the chromosome. Because the pht operon is located immediately upstream of the dbfA1A2 cistron, the dioxin-catabolic genes were dispersed on the genome of strain DBF63, while FN-catabolic genes were gathered on the plasmids.

Topics: Actinomycetales; Bacterial Proteins; Benzofurans; Biodegradation, Environmental; Carcinogens; Dioxins; Fluorenes; Genes, Bacterial; Molecular Structure; Open Reading Frames; Oxygenases; Phthalic Acids; Soil Microbiology

Biphenyl dioxygenase (Bph Dox) is responsible for the initial dioxygenation of biphenyl. The large subunit (BphA1) of Bph Dox plays a crucial role in determination of substrate specificity of biphenyl-related compounds including polychlorinated biphenyls (PCBs). Functional evolution of Bph Dox of Pseudomonas pseudoalcaligenes KF707 was accomplished by random priming recombination of the bphA1 gene, involving two rounds of in vitro recombination and mutation followed by selection for increased activity in vivo. Evolved Bph Dox acquired novel and multifunctional degradation capabilities not only for PCBs but also for dibenzofuran, dibenzo-p-dioxin, dibenzothiophene, and fluorene, the compounds scarcely attacked by the original KF707 Bph Dox. The modes of oxygenation were angular and lateral dioxygenation for dibenzofuran and dibenzo-p-dioxin, sulfoxidation for dibenzothiophene, and mono-oxygenation for fluorene. These enzymes also exhibited enhanced degradation abilities for PCB congeners, retaining 2,3-dioxygenase activity and gaining 3,4-dioxygenase activity, depending on the chlorine substitution of PCB congeners. Further mutation analysis revealed that the amino acid at position 376 in BphA1 is significantly involved in the acquisition of multifunctional oxygenase activities and mode of oxygenation.

Topics: Base Sequence; Benzofurans; Cloning, Molecular; Dioxins; DNA Primers; Fluorenes; Gas Chromatography-Mass Spectrometry; Mutagenesis, Site-Directed; Oxygenases; Polychlorinated Biphenyls; Pseudomonas; Recombination, Genetic; Thiophenes

The UV absorption spectra structures of carbazole, fluorene and dibenzofurane are studied using the atom monopole-dipole interaction (AMDI) model and atomic dipolar polarisabilities and effective charge given by Fraga. The absorption spectra corresponding to these molecules and their self-associations are presented. The original obtained results are discussed and compared to previous works.

Topics: Benzofurans; Carbazoles; Fluorenes; Molecular Structure; Spectrophotometry, Ultraviolet

The solubilizing effect of humic acids on fluorene and its NSO analogues carbazole, dibenzofuran and dibenzothiophene has been studied. The interaction between these substances and humic acids was found to depend significantly on the actual humic acid concentration. A pronounced decrease in the interaction constant, as well as in the water-organic matter partitioning coefficient was observed with increasing humic acid concentration. The effects are discussed in terms of concentration dependent macromolecular structural changes in the humic acids. A linear free energy relation for the interaction is suggested.

Topics: Benzofurans; Carbazoles; Carbon; Chemical Phenomena; Chemistry, Physical; Fluorenes; Fresh Water; Humic Substances; Solubility; Thiophenes; Water Supply

The regio- and stereospecific oxidation of fluorene, dibenzofuran, and dibenzothiophene was examined with mutant and recombinant strains expressing naphthalene dioxygenase from Pseudomonas sp. strain NCIB 9816-4. The initial oxidation products were isolated and identified by gas chromatography-mass spectrometry and nuclear magnetic resonance spectrometry. Salicylate-induced cells of Pseudomonas sp. strain 9816/11 and isopropyl-beta-D-thiogalactopyranoside-induced cells of Escherichia coli JM109(DE3)(pDTG141) oxidized fluorene to (+)-(3S,4R)-cis-3,4-dihydroxy-3,4-dihydrofluorene (80 to 90% relative yield; > 95% enantiomeric excess [ee]) and 9-fluorenol (< 10% yield). The same cells oxidized dibenzofuran to (1R,2S)-cis-1,2-dihydroxy-1, 2-dihydrodibenzofuran (60 to 70% yield; > 95% ee) and (3S,4R)-cis-3, 4-dihydroxy-3,4-dihydrodibenzofuran (30 to 40% yield; > 95% ee). Induced cells of both strains, as well as the purified dioxygenase, also oxidized dibenzothiophene to (+)-(1R,2S)-cis-1,2-dihydroxy-1, 2-dihydrodibenzothiophene (84 to 87% yield; > 95% ee) and dibenzothiophene sulfoxide (< 15% yield). The major reaction catalyzed by naphthalene dioxygenase with each substrate was stereospecific dihydroxylation in which the cis-dihydrodiols were of identical regiochemistry and of R configuration at the benzylic center adjacent to the bridgehead carbon atom. The regiospecific oxidation of dibenzofuran differed from that of the other substrates in that a significant amount of the minor cis-3,4-dihydrodiol regioisomer was formed. The results indicate that although the absolute stereochemistry of the cis-diene diols was the same, the nature of the bridging atom or heteroatom influenced the regiospecificity of the reactions catalyzed by naphthalene dioxygenase.

Topics: Benzofurans; Biotransformation; Dioxygenases; Escherichia coli; Fluorenes; Magnetic Resonance Spectroscopy; Multienzyme Complexes; Mutation; Oxidation-Reduction; Oxygenases; Pseudomonas; Recombination, Genetic; Stereoisomerism; Substrate Specificity; Thiophenes

Treatment of B6C3F1 mice with acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene and dibenzofuran resulted in induction of hepatic microsomal methoxyresorufin O-deethylase (MROD) activity. Acenaphthylene was the most potent inducer of MROD, a Cyp1a2-dependent activity, and was utilized as a prototypical inducer for this group of tricyclic hydrocarbons. Acenaphthylene (300 mg/kg) caused a > 80-fold induction of hepatic microsomal MROD activity; no induction was observed in kidney or lung. Analysis of induced hepatic microsomes with antibodies to Cyp1a1 and Cyp1a2 showed that acenaphthylene induced immunoreactive Cyp1a2 but not Cyp1a1 proteins and subsequent mRNA analysis confirmed with a cDNA probe for Cyp1a1 and Cyp1a2 that acenaphthylene induced Cyp1a2 but not Cyp1a1 mRNA. Results from nuclear run-on experiments using hepatic nuclei showed that acenaphthylene caused an approximately 4-fold increase in the rate of Cyp1a2 gene transcription in B6C3F1 mice. Results of competitive binding studies indicated that the tricyclic hydrocarbons did not competitively displace [3H]2,3,7,8-tetrachlorodibenzo-p-dioxin or [3H]benzo[a]pyrene from the mouse hepatic cytosolic aryl hydrocarbon (Ah) receptor or 4S carcinogen binding protein respectively. The data indicate that acenaphthylene and related tricyclic hydrocarbons induce Cyp1a2 gene expression in B6C3F1 mice via an Ah receptor-independent pathway. Thus, tricyclic hydrocarbons induce Cyp1a2 without the co-induction of Cyp1a1 and therefore these relatively non-toxic compounds can be used to further probe the role of Cyp1a2 in the metabolism and metabolic activation of diverse chemical carcinogens.

Topics: Acenaphthenes; Animals; Anthracenes; Antibodies, Monoclonal; Benzofurans; Crosses, Genetic; Cytochrome P-450 CYP1A1; Cytochrome P-450 CYP1A2; Cytochrome P-450 Enzyme System; Enzyme Induction; Female; Fluorenes; Male; Mice; Mice, Inbred C3H; Mice, Inbred C57BL; Microsomes, Liver; Oxidoreductases; Perylene; Phenanthrenes; Polychlorinated Dibenzodioxins; Receptors, Aryl Hydrocarbon

Staphylococcus auriculans DBF63, which can grow on dibenzofuran (DBF) or fluorene (FN) as the sole source of carbon and energy, was isolated. Salicylic acid and gentisic acid accumulated in the culture broth of this strain when DBF was supplied as a growth substrate. Also, the formation of 9-fluorenol, 9-fluorenone, 4-hydroxy-9-fluorenone, and 1-hydroxy-9-fluorenone was demonstrated, and accumulation of 1,1a-dihydroxy-1-hydro-9-fluorenone was observed when this strain grew on FN. On the basis of these results, the degradation pathways of DBF and FN were proposed. The analogous oxidation products of dibenzo-p-dioxin were obtained by incubation with DBF-grown S. auriculans DBF63 cells.

Topics: Benzofurans; Biodegradation, Environmental; Catechol 2,3-Dioxygenase; Catechols; Culture Media; Dioxins; Dioxygenases; Fluorenes; Oxidation-Reduction; Oxygenases; Soil Pollutants; Staphylococcus

The hepatic acid-soluble thiol content of striped mullet (Mugil cephalus) exposed to cadmium (10 mg/liter seawater), mercury (200 micrograms/liter), fluorene (100 micrograms/liter), dibenzofuran (750 micrograms/liter), or a 20% water-soluble fraction of a No. 2 fuel oil, and of winter flounder (Pseudopleuronectes americanus) exposed to pentachlorophenol (200 micrograms/liter) for up to 3 weeks was determined. Exposure to these chemicals caused an elevation of hepatic acid-soluble thiol content over control values. Similarly, the acid-soluble thiol content was 1.75 times control values 24 hr after injection with acetaminophen (40 mg/100 g body wt, ip). In contrast, hepatic acid-soluble thiol concentrations did not fluctuate after feeding or during short-term starvation, or after acute or chronic physical trauma. Thus, the increase in hepatic acid-soluble thiols observed in mullet appears to be a specific response to chemical insult. The effect of chemical exposure on specific thiols can vary with the compound under investigation. Glutathione accounted for most of the acid-soluble thiol increase observed in mullet exposed to oil, whereas other acid-soluble thiols were also elevated after exposure to cadmium. Injection of [14C]glycine into cadmium- and oil-treated mullet showed that hepatic uptake of this amino acid substrate and its incorporation into hepatic glutathione increased after chemical exposure. The proportion of the total [14C]glycine in the liver incorporated into glutathione was unchanged after oil exposure, but was significantly increased in cadmium-exposed fish. These results suggest that chemicals may elevate glutathione content by enhancing the hepatic uptake of amino acid substrates and also the activity of biosynthetic enzymes.

Topics: Acetaminophen; Animals; Benzofurans; Cadmium; Cysteine; Fishes; Fluorenes; Food Deprivation; Fuel Oils; Glutathione; Glycine; Liver; Mercury; Pentachlorophenol; Sulfhydryl Compounds