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PubMed1982

3-Methylcholanthrene-inhibition of hepatocarcinogenesis in the rat due to 3'-methyl-4-dimethylaminoazobenzene or 2-acetylamino-fluorene: a comparative study.

Male Leeds strain rats were given a diet containing either 0.06% 3'-methyl-4-dimethylaminoazobenzene (3'-MeDAB) or 0.05% 2-acetylaminofluorene (2-AAF), alone or together with 0.0067% 3-methylcholanthrene (MeCh). MeCh both reduced the incidence of hepatic neoplasms induced by 3'-MeDAB and delayed their development. With 2-AAF, however, inhibition of hepatocarcinogenesis by MeCh only appeared to operate during the period of treatment; thereafter the incidence of tumours rose rapidly and this was accentuated if dietary MeCh continued to be administered after the period of combined 2-AAF and MeCh treatment, suggesting a secondary, promoting effect of MeCH. In contrast, the inhibition by MeCh of carcinogenesis of Zymbal's gland due to 2-AAF was almost complete. Thus, in the long term MeCh has different effects upon 3'-MeDAB and 2-AAF carcinogenesis in the rat liver.

2-Acetylaminofluorene↗
PubMed2001

Comparative analysis of PAH:DNA adducts formed in lung of mice exposed to neat coal tar and soils contaminated with coal tar.

7H-Benzo[c]fluorene (benzo[c]fluorene) is a major DNA adduct forming component of coal tar in lung of mice. The present study evaluated the types of PAH:DNA adducts formed from different neat coal tar samples and soils contaminated with coal tar. Mice were fed diets containing coal tar either neat or as a contaminant in an environmental soil sample for 14 days, and the types of chemical:DNA adducts formed in lung were evaluated using 32P-postlabeling and HPLC analysis. Three major DNA adducts derived respectively from benzo[b]fluoranthene (B[b]F), benzo[a]pyrene (B[a]P), and benzo[c]fluorene were detected in three of the four neat coal tar samples evaluated. In contrast, only a single major DNA adduct derived from benzo[c]fluorene was observed with the remaining tar sample. Ingestion of coal tar contaminated soil resulted in DNA adducts primarily derived from benzo[c]fluorene and B[b]F; a B[a]P derived DNA adduct was not detected. The DNA adducts derived from benzo[c]fluorene and B[b]F but not B[a]P were also observed with animals fed methylene chloride extracts of three of these soils but not the one designated A1000H soil. However, the extract of A1000H resulted in a B[a]P:DNA adduct being detected along with adducts formed from B[b]F and benzo[c]fluorene. The selective formation of the benzo[c]fluorene:DNA adduct with coal tar contaminated soils indicates that the in vivo systemic bioavailability and/or metabolism of benzo[c]fluorene is relatively high when compared to other DNA adducting hydrocarbons within coal tar. Benzo[c]fluorene may play a critical role in the potential of contaminated soil to induce a toxicological response in animals.

Administration, Oral↗
PubMed2006

Application of multi-component Damage Assessment Model (MDAM) for the toxicity of metabolized PAH in Hyalella azteca.

Biotransformation and time-dependent toxicity of pyrene and fluorene, in the presence and absence of the biotransformation inhibitor 6-propylpiperonyl butyl diethylene glycol ether known as piperonyl butoxide (PBO), were investigated in Hyalella azteca. Toxicokinetics and biotransformation were determined in both short- and longterm experiments. For pyrene, the uptake rate coefficient (ku = 99 +/- 9 L kg(-1) h(-1)), elimination rate constant for parent compound (kep = 0.050 +/- 0.008 h(-1)), biotransformation rate constant (km = 0.016 +/- 0.003 h(-1)), and elimination rate constant for metabolites (kem = 0.021 +/- 0.007 h(-1)) were determined from a short-term study. For fluorene, ku (130 +/- 30 L kg(-1) h(-1)) and kep (1.7 +/- 0.2 h(-1)) were estimated based on km (0.015 +/- 0.002 h(-1)) and kem (0.011 +/- 0.002 h(-1)) determined from a long-term study. At steady state, the percent metabolites for pyrene and fluorene were 43% and 58%, respectively, determined from km/(km +/- kem). Time-dependent toxicity was determined as both lethal water concentration and lethal body residue in the presence and absence of PBO. Co-exposure to PBO decreased the median lethal residue (LBR50) for parent pyrene and shortened the median lethal time (LT50). Pyrene toxicity was explained by the body residues of parent pyrene and PBO, where the metabolites' contribution was negligible. Forfluorene, co-exposure to PBO increased the LBR50 for parent fluorene and shortened the LT50. Thus, fluorene metabolites contributed significantly to the toxicity. Using a multicomponent damage assessment model, the toxicodynamic parameters, damage accrual rate coefficient, and damage recovery rate constant for parent pyrene and parent fluorene were very similar and estimated to be from 0.009 to 0.020 micromol(-1) g h(-1) and from 0.003 to 0.013 h(-1), respectively, and the incipient LBR50 at the infinite time (LBR50(t = infinity)) was from 0.24 to 0.46 micromol g(-1), respectively. These values are similar to the reported LBR50(t = infinity) for other nonpolar narcotics such as pentachlorobenzene (PCBz, 0.38 +/- 0.13 micromol g(-1)) and dichlorophenylchloroethylene (DDE, 0.41 +/- 0.19 micromol g(-1)). For fluorene metabolites, these values were 0.10 +/- 0.03 micromol(-1) g h(-1), 0.034 +/- 0.021 h(-1), and 0.33 +/- 0.23 micromol g(-1), respectively. However, for pyrene metabolites, since toxicity of pyrene metabolites was negligible, the parameters could not be estimated.

Amphipoda↗
PubMedDate not supplied

Arylamination and arylation of 4,4,4-trifluoro-1-phenyl-1,3-butanedione with N-acetoxy derivatives of 2-aminofluorene.

The present study investigated the reaction of carcinogenic electrophiles with beta-diketones which possess an active methylene group. N-Acetoxy-2-(acetylamino)fluorene bound to tRNA at 37 degrees C, pH 7.0, and this reaction was inhibited by 4,4,4-trifluoro-1-phenyl-1,3-butanedione or 2-thenoyltrifluoroacetone. N-Acetoxy-2-(acetylamino)fluorene reacted with these active methylene compounds to form transitory 3-substituted 2-(acetylamino)fluorene intermediates, which, following cleavage of the trifluoroacetyl group, yielded 3-phenacyl-2-(acetylamino)fluorene or 3-(2-thenoylmethyl)-2-(acetylamino)fluorene. N-Acetoxy-2-[(trifluoroacetyl)amino]fluorene reacted with 4,4,4-trifluoro-1-phenyl-1,3-butanedione to yield two products, N-phenacyl-1-(trifluoroacetyl)-2-aminofluorene and N-phenacyl-3-(trifluoroacetyl)-2-aminofluorene. The ratio of these two products was approximately 1:2. The same N-phenacyl products were produced by incubation of the beta-diketone, N-hydroxy-2-(acetylamino)fluorene, and rat liver cytosol which catalyzed the formation of N-acetoxy-2-aminofluorene. Thus, the inhibitions by beta-diketones of nucleic acid-binding and bacterial mutagenesis of carcinogens are likely due to their trapping of the carcinogens.

Acetoxyacetylaminofluorene↗
PubMed1978

Synthesis of spirofluorenes of biological interest.

1'-Substituted spiro[fluorene-9,3'-pyrrolidine-2',5'-diones], 1',1''' - (1,4-piperazinediyldimethylene) bis[spiro[fluorene-9,3'-pyrrolidine-2',5'-dione]], and 1'-arylspiro[fluorene-9,3'-pyrrolidines] were synthesized from spiro[fluorene-9,3'-tetrahydrofuran-2',5'-dione]. The rat passive cutaneous anaphylaxis assay showed that one compound possessed slight antiallergic activity. Synthesis of 3-substituted 1-aryl-4-oxospiro[azetidine-2,9'-fluorenes] and 1,1''-p-phenylenebis[4-oxospiro[azetidine-2,9'-fluorenes]] was achieved via the reaction of appropriate N-fluorenylideneanilines with tert-butylcyanoketene and cyclopentamethyleneketene, respectively.

Animals↗
PubMed1994

Nongenotoxic effects of polycyclic aromatic hydrocarbons and their oxygenation by-products on the intercellular communication of rat liver epithelial cells.

Since polycyclic aromatic hydrocarbons (PAHs) are known to have epigenetic effects, we evaluated the effect of the parent chemical and the ozonated products on in vitro cell to cell communication bioassays which measures a nongenotoxic event. The scrape loading/dye transfer (SL/DT) technique was used to determine the effect of the following PAHs on gap-junction intercellular communication (GJIC): fluorene, 1-methyl-fluorene, fluoranthene, anthracene, 9-methyl-anthracene, phenanthrene, pyrene, benzo(a)pyrene, and benzo(e)pyrene. The methylated PAHs were more inhibitory to GJIC than the unmethylated counterparts. Fluoranthene, which has an additional ring added to fluorene, was more effective in inhibiting GJIC than fluorene. The three-ringed PAHs were also more inhibitory than the four- and five-ringed PAHs. A time-course study of fluoranthene and of pyrene resulted in maximal inhibition occurring within 30 min of incubation with the cells. The cells recovered from the inhibition within 1 hr after fluoranthene and pyrene were removed from the cell culture medium. Pyene, vbenzo(a)pyrene, fluorene, and fluoranthene were ozonated until the parent compound was completely eliminated as determined by reverse-phase high-pressure liquid chromatography (RP-HPLC). An increased level of inhibition of GJIC was observed for the ozonated mixtures of by-products of pyrene, fluoranthene, and benzo(a)pyrene, but not for fluorene, as monitored with the SL/DT technique. The products of the ozonated pyrene mixture were fractionated and collected by RP-HPLC. Each fraction was found to be inhibitory to GJIC as monitored by fluorescence recovery after photobleaching. In conclusion, current treatment technologies, such as ozonation or biologically based oxidations and methylations, do not necessarily eliminate toxicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2003

Overcrowded 1,8-diazafluorenylidene-chalcoxanthenes. Introducing nitrogens at the fjord regions of bistricyclic aromatic enes.

The effects of introducing nitrogen atoms in the fjord regions and chalcogen bridges on the conformations of overcrowded bistricyclic aromatic enes (1, X not equal to Y) (BAEs) were studied. 9-(9'H-1',8'-Diazafluoren-9'-ylidene)-9H-thioxanthene (12), 9-(9H-1',8'-diazafluoren-9'-ylidene)-9H-selenoxanthene (13), 9-(9'H-1',8'-diazafluoren-9'-ylidene)-9H-telluroxanthene (14), 9-(9' H-1',8'-fluoren-9-ylidene)-9H-xanthene (15) and 9-(9' H-1',8'-fluoren-9'-ylidene)-9H-fluorene (16) were synthesized by two-fold extrusion coupling reactions of 1,8-diaza-9H-fluoren-9-one (19)/chalcoxanthenthiones (24-27) (or /9H-fluorene-9-thione (30)). The 1',8'-diazafluoren-9-ylidene-chalcoxanthenes (11) were compared with the respective fluoren-9-ylidene-chalcoxanthenes (10). The structures of 12-16 were established by 1H, 13C, 77Se, and 125Te NMR spectroscopies. The crystal and molecular structures of 12-14 were determined by X-ray analysis. The yellow molecules of 12-14 adopted mono-folded conformations with folding dihedrals in the chalocoxanthylidene moieties of 62.7 degrees (12), 62.4 degrees (13) and 59.9 degrees (14). The folding dihedrals in the respective 1',8'-diazafluorenylidene moieties were very small, ca. 2 degrees, compared with 10.2/8.0 degrees in (9'H-fluoren-9'-ylidene)-9H-selenoxanthene (7). A 5 degree pure twist of C9=C9' in 14 is noted. The degrees of overcrowding in the fjord regions of 12-14 (intramolecular non-bonding distances) were relatively small. The degrees of pyramidalization of C9 and C9' were 17.0/3.0 degrees (12), 17.4/2.4 degrees (13) and 2.2/2.2 degrees (14). These high values in 12 and 13 stem from the resistance of the 1.8-diazafluorenylidene moiety to fold and from the limits in the degrees of folding of the thioxanthylidene and selenoxanthylidene moieties (due to shorter S10-C4a/S10-C10a and Se10-C4a/Se10-C10a bonds, as compared with the respective Te-C bonds in 14). The molecules of 15 and 16 adopt twisted conformations, a conclusion drawn from the 1H NMR chemical shifts of the fjord regions protons (H1 and H8) at 8.70 (15) and 9.00 ppm (16) and from their colors and UV/VIS spectra: 15 is purple (lambdamax = 521 nm) and 16 is orange-red. A comparison of the NMR spectra of 11 and 10 (deltadelta = delta(11) -delta(10)) showed substantial downfield shifts of 0.56-0.62 ppm of the fjord regions protons of twisted 15 and 16: deltadelta (C9) were negative (upfield): -4.0 (12), -3.7 (13), -3.4 (14), -7.1 (15), -5.0 ppm (16), while deltadelta (C9') were positive (downfield) = +6.8 (12), +6.5 (13), +5.8 (14), + 11.7 (15), +7.7 ppm (16). In 15, deltadelta (C9) - deltadelta (C9') = + 18.8 ppm, attributed to a push-pull character and significant contributions of zwitterionic structures in the twisted conformation. The 77Se and 125Te NMR signals of 13 and 14 were shifted upfield relative to the respective fluorenylidene-chalcoxanthene derivatives: deltadelta77Se = 17.2 ppm and deltadelta125Te = 22.0 ppm. The presence of the nitrogen atoms (N1' and N8') in 13 and 14 causes shielding of the selenium and tellurium nuclei.

Journal Article↗
PubMed2002

Carbonyl reduction of the potential cytostatic drugs benfluron and 3,9-dimethoxybenfluron in human in vitro.

Benfluron (B, [5-(2-N-oxo-2-N',N"-dimethylaminoethoxy)-7-oxo-7H-benzo[c]fluorene]) is a potential benzo[c]fluorene antineoplastic agent with high activity against a broad spectrum of experimental tumors in vitro and in vivo. The structure of B has been modified to repress its rapid deactivation through carbonyl reduction on C7. 3,9-Dimethoxybenfluron (D, [3,9-dimethoxy-5-(2-N-oxo-2-N',N"-dimethylaminoethoxy)-7-oxo-7H-benzo[c]fluorene]) is one of the B derivatives developed. The present paper was designed to compare the C7 carbonyl reduction of B and D in microsomes, cytosol and hepatocytes from human liver. Two purified human enzymes, microsomal 11beta-hydroxysteroid dehydrogenase 1 (11beta-HSD 1) and cytosolic carbonyl reductase, were tested if they are responsible for B and D carbonyl reduction in the respective fractions. Indeed, carbonyl reduction of D in comparison to that of B was 4 and 6-10 times less extensive in human liver microsomes and cytosol, respectively. Moreover, about 10-20 times higher amounts of dihydro B than dihydro D were detected in primary culture of human hepatocytes. 11beta-HSD 1 was shown to be able to reduce B and D. For this enzyme, about 10 times higher rates of carbonyl reduction were observed for B than for D. Likewise, CR participates in B and D carbonyl reduction, although smaller amounts of both reduced metabolites were detected. In summary, carbonyl reduction of D was significantly less extensive than that of B in all in vitro experiments. This lower rate of D inactivation was especially pronounced in hepatocytes which represent a close to in vivo situation. Our results clearly demonstrate that dimethoxy substitution protects the carbonyl group of the benzo[c]fluorene moiety against the deactivation by microsomal and cytosolic reductases. Detailed knowledge on the participating enzymes may serve as a basis for the co-application of specific inhibitors in chemotherapy to further improve the pharmacokinetics of benzo[c]fluorene derivatives.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1998

n-alkyl fluorenyl phases in chromatography. I. Synthesis and characterization.

A new class of silica gel-bound fluorene phases is described. The compounds are synthesized via reaction of fluorenyl lithium with omega-alkenyl bromides leading to 9-(5'-hexenyl)-9H- and 9-(9'-decenyl)-9H-fluorene (1 and 2), followed by hydrosilation reactions with different hydrosilanes. The resulting omega-functionalized silylalkyl fluorenes 3a(T0), 3b(T0), 4a(T0), 4b(T0) and 4c(M0) (Scheme 1) react with surface silanol groups of silica gel to generate the new fluorene phases 3a(Tn)(Qm)y, 3b(Tn)(Qm)y, 4a(Tn)(Qm)y, 4b(Tn)(Qm)y and 4c(M1)(Qm)y. The phases are characterized by employing 1H, 13C and 29Si solid-state nuclear magnetic resonance spectroscopy. Their applicability in high-performance liquid chromatography is proved by the Sander and Wise test (SRM 869). In contrast to conventional n-alkyl phases, pi-pi interactions are additionally involved in the separation process and, therefore, the retention times of the polycyclic aromatic hydrocarbons sample molecules depend on the ligand densities of the applied fluorene phases.

Chromatography, High Pressure Liquid↗
PubMed1999

n-Alkyl fluorenyl phases in chromatography. II. Dynamic behavior and high-performance liquid chromatography applications.

The dynamic behavior of two n-hexyl fluorenyl phases (fluorene-6A [3a(Tn)(Qm)y], fluorene-6B [3b(Tn)(Qm)y]) and three n-decyl fluorenyl phases (fluorene-10A [4a(Tn)(Qm)y], fluorene-10B [4b(Tn)(Qm)y], and fluorene-10C [4c(M1)(Qm)y]) is investigated by solid-state nuclear magnetic resonance (NMR) spectroscopy using the dipolar filter technique with both 13C and 1H detection. These results are compared with those from other dynamic measurements, like the relaxation times in the rotating frame (T1pH) and the variation of the contact time (T(CH)). Additionally, another type of a fluorenyl phase [5a(Tn)(Qm)y], which has an aromatic moiety connected to the silica gel by amido couplings, was also investigated by the dipolar filter method. The solid-state NMR dynamic measurements indicate an increased mobility of the n-alkyl fluorenyl phases compared to the amido coupled fluorenyl phase. The lower the ligand density of the studied n-alkyl fluorenyl phases, the higher their mobility. The separation behavior of the respective phases in high-performance liquid chromatography was investigated with samples containing polycyclic aromatic hydrocarbons and nitro explosives. Depending on the amount of the chemically bound aromatic moiety and the length of their n-alkyl spacer groups, pi-pi interactions with the solute molecules are involved in the separation process and cause it to proceed at a different rate. Therefore, n-alkyl fluorenyl phases can be classified as mixed-mode phases.

Chromatography, High Pressure Liquid↗
PubMed2005

Synthesis and energy-transfer properties of hydrogen-bonded oligofluorenes.

A set of fluorene oligomers has been synthesized by stepwise palladium-catalyzed (Suzuki) couplings of fluorene monomers. Ureidopyrimidinones (UPy), functional groups that can dimerize via quadruple hydrogen bonds, were attached to both ends of the oligofluorenes. The resulting bis-UPy-terminated oligomers self-assemble into supramolecular chain polymers. For comparison, oligofluorenes of the same oligomer lengths but without terminal hydrogen-bonding groups were synthesized. Chains of hydrogen-bonded fluorenes can be simply endcapped by a variety of chain stoppers, molecules that have one UPy group. In this manner, we have endcapped the hydrogen-bonded fluorene chains with either oligo(p-phenylenevinylene) or perylene bisimide. Energy-transfer experiments in solution and the solid state demonstrate that oligofluorenes can donate energy to a variety of energy acceptors, but that this energy transfer occurs most effectively when the donor fluorene is hydrogen-bonded to the acceptor.

Catalysis↗
PubMed1999

A colorimetric-enzymatic microassay for the quantitation of antibody-dependent complement activation.

In this report we describe a reliable, sensitive, safe, and easy way to assess antibody-dependent complement-mediated hemolysis. The assay is based on the quantitation of hemoglobin (Hb) released from lysed erythrocytes indirectly, through the generation of fluorene blue, a compound formed from 2-7 diaminofluorene in an enzymatic reaction catalyzed by the Hb molecule. The fact that Hb is the most abundant protein within a mature RBC (approximately 10(11) molecules per cell) and possesses pseudoperoxidase activity, makes the fluorene blue-coupled assay more sensitive than the simple estimation of Hb adsorption at 410 nm (Soret adsorption maxima of Hb), and as sensitive and reliable as its radioactive equivalent based on the release of 51Cr from previously loaded RBCs. Using this assay chimeric mouse-human anti-dansyl antibodies, comprising all the human IgG isotypes, were tested for their ability to mediate complement activation. The results obtained agreed with previously reported data, confirming that the fluorene blue-coupled assay is reliable. This assay also has significant advantages over the radioactive-based assay in that the reagents used are inexpensive, and the concerns of using radioactivity and the associated hazards are obviated. Because there is no need for loading the target cells with the analyte to be detected since RBCs are already loaded with Hb, the fluorene blue-coupled assay is simpler and eliminates many steps in comparison to the 51Cr release based assay.

Animals↗
PubMed2005

Theoretical study of vibrational and optical spectra of methylene-bridged oligofluorenes.

We report a systematic characterization of methylene-bridged fluorene oligomers constructed of two, four, six, and eight aromatic rings using time-dependent density functional theory (TDDFT), the ab initio approximate coupled-cluster singles and doubles (CC2) method, and semiempirical spectroscopic Zerner's intermediate neglect of differential overlap method (ZINDO/S). Geometry optimizations have been performed for the ground state and for the first electronically excited state. Vertical excitations and the fluorescence transition from the lowest excited state have been calculated. Computed ground-state geometries and infrared spectra for fluorene are in good agreement with experimental results. The RI-CC2 and ZINDO/S absorption and fluorescence spectra agree very well with the available experimental data for studied fluorene oligomers and for para oligophenylenes films. On the other hand, TDDFT calculations underestimate excitation and fluorescence energies systematically for larger systems (N > 4) in comparison with the above-mentioned results. The effective conjugation length was estimated to 13-14 repeat units. The computed radiative lifetimes for the fluorene molecule show good agreement with experiment within realistic expectations. The decrease of the radiatiave fluorescence lifetime with the increase in the conjugation length has been discussed also.

Computer Simulation↗
PubMed2004

Degradation of aromatic hydrocarbons by Sphingomonas paucimobilis strain EPA505.

To determine the substrate range capability of Sphingomonas paucimobilis strain EPA505, a number of aromatic compounds were tested as potential growth substrates. Strain EPA505 grew on phenanthrene, naphthalene, fluoranthene, toluene, benzoic acid, 2,3- and 3,4-dihydroxybenzoic acids, 1-chloro-2,4-dinitrobenzene, anthracene, 2-hydroxy-3-naphthoic acid and 1-hydroxy- 2-naphthoic acid, salicylic acid, and catechol. Strain EPA505 was unable to grow on coumarine 3-carboxylic acid, naphthalene dicarboxylic acid, acenaphthene, chrysene, pyrene, benzo[b]fluoranthene, and fluorene. Catabolic products were not detected or identified when the bacterium was incubated with coumarine 3-carboxylic acid, naphthalene dicarboxylic acid, acenaphthene, chrysene, or benzo[b]fluoranthene. Dihydroxypyrene, the ortho ring fission product of pyrene, and 10-hydroxy-1- phenanthroic acid were detected when the bacterium was incubated with pyrene. The open rings of benzo[b]fluoranthene, hydroxyacephenanthroic acid, hydroxyacephenanthrene, and phenanthrene anhydride, catabolites of benzo[b]fluoranthene degradation, were detected with Tn5 mutants of EPA505. With strain EPA505, both 9-fluorenone and an open ring fission product accumulated during incubation with fluorene. Other catabolites beyond the open ring of fluorene were detected, specifically dihydroxyfluorene, hydroxy-9-fluorenone, dihydroxy-9-fluorenone, hydroxyindane, and a putative glutathione-conjugated benzylanhydride. Benzylanhydride appeared to be a final end product of fluorene degradation by strain EPA505.

Molecular Weight↗