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PubMedDate not supplied

Determination of fluorene in fish, sediment, and plants.

Methods and their applications are described for the determination of fluorene in fish, sediment, and plants. Sample extracts are enriched by using 2 or more of the following: gel permeation, silica gel, potassium silicate, sulfuric acid-impregnated silica gel, and activated carbon. Efficiency was improved by applying the adsorbents in combination or as tandem enrichment modules. Analyses by liquid chromatography (LC) with ultraviolet or fluorescence detection (LC/UV or LC/F) yielded limits of detection of 30, 3, and 30 ng/g and average recoveries of 80, 81, and 74% for fish, sediment, and plants, respectively.

Animals↗
PubMed1979

Establishment of photoaffinity label derivatives of fluorene as probes in studies of chemical carcinogenesis in mammalian cell culture.

Several azido fluorenes, photosensitive analogs of the established carcinogen 2-acetylaminofluorene, have been synthesized to serve as probes in chemical carcinogenesis and mutagenesis studies. Unlike 2-acetylaminofluorene, these compounds do not require metabolic activation. However, alkylation to critical targets is achieved through the generation of nitrenes by photolysis at 360 nm in situ. We have found that the bifunctional azidofluorenes 2,5-diazidofluorene and 2,7-diazidofluorene were more toxic to and more transforming of the mouse embryo C3H 10T1/2 clone 8 cells when photolyzed in situ than were the monofunctional azides 2-azidofluorene and 7-bromo-2-azidofluorene. When the drugs were photolyzed in phosphate-buffered saline (pH 7.4) and then added to the cells these preirradiated derivatives were not transforming but were slightly toxic. However, there is not relationship between the number of photosensitive azido groups and the cytotoxicities of the preirradiated derivatives as measured by the plating efficiency method. The transformation experiments were performed under conditions in which photolysis was carried out for as little as 15 sec. This is significant because the major events that lead to oncogenesis apparently can occur within this narrow time channel, thereby making the drugs excellent probes in studies in chemical carcinogenesis. Although near ultraviolet light alone may transform the cells (8 to 16 min of irradiation), under the conditions studied ultraviolet light was neither toxic nor transforming.

Affinity Labels↗
PubMed1984

Derivatives of benzo(c)fluorene. X. Inhibitory effect of Benfluron on cellular immunity.

The effect of a cytostatic drug Benfluron-- 5(2-N,N-dimethyl-amino-ethoxy)-7-oxo-7H-benzo(c)fluorene hydrochloride was tested in mice on skin graft survival, graft-versus-host reaction (GVHR) and for mitogenic stimulation of human lymphocytes. Application of Benfluron resulted in a prolonged skin graft survival. The regional and systemic GVHR was potentially inhibited by p. o. administration of Benfluron at a dose of 100 mg/kg of body weight. Allogeneic spleen cells incubated with Benfluron at concentration of 5-20 micrograms/ml showed reduced capability to induce GVHR. PHA or PWM stimulation of lymphocytes was completely inhibited in the presence of 2 micrograms/ml Benfluron. Benfluron as a potent immunosuppressive agent can be considered useful for the prevention of GVHR.

Animals↗
PubMed1984

Derivatives of benzo(c)fluorene. XI. Effect of Benfluron on hemopoietic stem cells.

The effect of Benfluron-- 5-(2-N,N-dimethylamino-ethoxy)-7-oxo-7H-benzo(c)fluorene hydrochloride--on hemopoietic stem cells was tested by the production of spleen cell colonies (CFU-S) in irradiated mice following application of bone marrow cells and by the production of hemopoietic colonies (CFU-C) in semisolid agar. The reduced numbers of CFU-S were found in mice applied Benfluron or Benfluron-treated bone marrow cells. The increased numbers of CFU-S, however, were found in mice receiving bone marrow cells from Benfluron-treated donors. The production of CFU-C was decreased after 2 h incubation of bone marrow cells with 0.5-5 micrograms/ml of Benfluron, and fully inhibited at higher concentrations.

Animals↗
PubMed1983

Antiviral effects of amino acid derivatives with the fluorene substituent on murine leukemia viruses.

Two new amino acid derivatives with the fluorene substituent, when administered ip to female inbred ICR-CD1 mice inoculated with Friend murine leukemia virus, significantly inhibited virus-induced splenomegaly, reduced viable virus titers in spleen and plasma, and significantly prolonged survival time. These compounds also inhibited multiplication of the strains of the Friend and Moloney murine leukemia viruses in a cell culture system. The action of these compounds on murine leukemia virus was presumely different from that of tilorone.

Animals↗
PubMed1981

Antileukemic effects of 5-(2-dimethylaminoethoxy)-7-oxo-7H-benzo(c) fluorene, substance VUFB 13 468, on L1210 and La leukemia.

The antineoplastic effect of 5-(2-dimethyl-aminoethoxy)-7-oxo-7H-benzo(c) fluorene, substance VUFB 13 468, was studied in leukemia L1210 and leukemia La. It was found that the test substance, in the form of base and in the form of hydrochloride, influenced favorably the survival of leukemic mice, in which the life span increased in dependence on the dose and the scheme of its application.

Animals↗
PubMed2002

Bond angle versus torsional deformation in an overcrowded alkene: 9-(2,2,2-triphenylethylidene)fluorene.

Competition between bond angle and torsional strain in sterically crowded alkenes generally causes twisting in tetrasubstituted alkenes, while most structurally characterized trisubstituted alkenes are planar. To investigate structural effects of steric repulsion between a planar aromatic ring and a vicinal triphenylmethyl (trityl) group, 9-(2,2,2-triphenylethylidene)fluorene (1 a) was synthesized by reaction of 9-bromomethylenefluorene with triphenylmethyllithium. For comparison with a less strained analogue, 9-ethylidenefluorene (1 b) was prepared by reaction of fluorenone with ethylmagnesium bromide. The X-ray crystal structures show that the difference between bond angles at the 9-fluorenyl carbon atom is much larger for 1 a (12.9 degrees) than 1 b (2.6 degrees). Bond angle and torsional deformations were compared theoretically (HF/6-31+G*) with the tert-butyl analogue (1 c), 1,2,2-tri-tert-butylethene (7), and 2,4,4-trimethyl-2-pentene (8) and crystallographically with six known 1,1-diaryl-2-tert-alkylethenes (2). The trisubstituted alkenes formed three groups with 1) large angle distortion with moderate twisting (1 a, 1 b, and 7), 2) moderate bending with a large range of torsional angles (2), and 3) little bending or twisting (1 b and 8). For the entire series, there appears to be a delicate balance between angle and torsional deformation, but twisting appears to produce smaller relief from steric strain than angle bending. In the crystallographically characterized trisubstituted alkenes, the choice between the two is mainly determined by more subtle packing forces.

Journal Article↗
PubMed2005

One- and two-photon fluorescence anisotropy of selected fluorene derivatives.

The steady-state excitation anisotropy spectra of fluorene derivatives were measured in viscous solvents, under the one- and two-photon excitation, over a broad spectral range (UV-Visible). The orientation of their absorption transition moments for the first, S0 --> S1, and second, S0 --> S2, excited states were determined. It was shown experimentally that a decrease in the angle between S0 --> S1 and S0 --> S2 transitions corresponded to an increased value of two-photon absorption (2PA) cross section for these molecules. Two-photon excitation anisotropy was nearly constant over the spectral region investigated (in contrast to one-photon excitation anisotropy spectra) and can be roughly explained by a simple model of 2PA based on the single intermediate state approximation. For comparison, the same trend in two-photon excitation anisotropy was observed for Rhodamine B in glycerol.

Journal Article↗
PubMedDate not supplied

Relationships between structure of nitrated arenes and their mutagenicity in Salmonella typhimurium; 2- and 2,7-nitro substituted fluorene, phenanthrene and pyrene.

In order to elucidate the mechanisms of mutagenic activation of nitroarenes, we studied the relationships between the mutagenic potency and chemical structure of 2-nitro- and 2,7-dinitro-arenes including nitrated fluorene (Fl), dihydrophenanthrene (DHPh), phenanthrene (Ph), tetrahydropyrene (THPy), dihydropyrene (DHPy) and pyrene (Py) together with 9-NO2-Ph, 1-NO2-Py and 1.3-diNO2-Py. The mutagenicity tests were carried out on Salmonella typhimurium TA98, TA98NR and TA98/1,8-DNP6 in the absence of S9 mix. The order of mutability of mononitro- and dinitro-arenes in TA98 is as given below: 2-NO2-THPy less than 2-NO2-Fl less than 2-NO2-DHPh less than 9-NO2-Ph less than 2-NO2-Ph less than 2-NO2-DHPy less than 1-NO2-Py less than 2-NO2-Py, and 2,7-diNO2-DHPh less than 2,7-diNO2-Fl less than 2,7-diNO2-THPy less than 2,7-diNO2-Ph less than 2,7-diNO2-DHPy less than 2,7-diNO2-Py less than 1,3-diNO2-Py. 9-NO2-Ph and 1-NO2-Py, which have been detected in environmental samples, are not as potent mutagens as 2-nitrated phenanthrene and pyrene, respectively. 2-NO2THPy (37.7 rev/nmole) was a weak mutagen, but 2,7-diNO2-THPy (3197 rev/nmole) was as potent a mutagen as 2,7-diNO2 (3925 rev/nmole). Tetrahydropyrene has a twisted form in its structure. 1,3-diNO2-Py (99660 rev/nmole) was more mutagenic than 2,7-diNO2-Py (37960.0 rev/nmole), and their mutagenicities were correlated with the behavior of the K-band in their UV spectra by the introduction of nitro groups on pyrene.

Biotransformation↗
PubMed1996

Cytoxicity of [(5,6-dichloro-9a-n-propyl-2,3,9,9a-tetrahydro-3-oxo-1H fluoren-7-yl)oxy]acetic acid, an agent known to reduce brain edema.

A known agent, [(5,6-dichloro-9a-n-propyl-2,3,9,9a-tetrahydro-3-oxo-1H fluoren-7-yl)oxy]acetic acid, which blocks brain edema, was also shown to be a potent cytotoxic agent in leukemia cells. The major site of action of the agents appears to be in the de novo purine synthetic pathway in L1210 leukemic cells. Both PRPP amido transferase and IMP dehydrogenase activities were suppressed by the agent. The inhibition of both regulatory enzymes of the pathway along with the reduction of dihydrofolate reductase activity would account for the observed suppression of DNA and RNA syntheses and subsequent cancer cell death.

Acetates↗
PubMed2004

Design and synthesis of DNA-intercalating 9-fluoren-beta-O-glycosides as potential IFN-inducers, and antiviral and cytostatic agents.

Novel 9-fluoren-beta-O-glycosides, designed as DNA-intercalating agents in structural correlation with antiviral tilorone and anticancer anthracyclines, have been prepared with yields in beta-anomers ranging between 25 and 63%. They have been screened for antiproliferative, immunostimulating and antiviral properties against HSV-1 and HSV-2 viruses. Compounds displaying significant antiviral activity against HSV-2 are acetylated 1 and deprotected 6 9-fluorenyl-O-d-arabinopyranoses, whereas 9-fluorenyl-O-d-glucopyranose 3 is the most effective on HSV-1 replication, followed by 1 and 6. The conformational properties of these compounds have been evaluated by molecular modelling techniques.

Antineoplastic Agents↗
PubMed2004

Synthesis of N-(fluoren-9-ylmethoxycarbonyl)glycopyranosylamine uronic acids.

The synthesis of 10 N-(fluoren-9-ylmethoxycarbonyl)glycopyranosylamine uronic acids that are amenable to solid-phase synthesis is described. The general synthetic strategy involves initial incorporation of the protected amine, followed by selective TEMPO oxidation of C-6 hydroxyl groups to give the corresponding Fmoc-protected sugar amino acids. Amine incorporation may be accomplished from aminolysis of the free sugar or from glycosyl azide reduction. The reactions can be carried out on multigram scale, providing access to unique monomer units for future incorporation into combinatorial library syntheses.

Combinatorial Chemistry Techniques↗
PubMed2002

A brominated-fluorene insect neuropeptide analog exhibits pyrokinin/PBAN-specific toxicity for adult females of the tobacco budworm moth.

An analog of the insect pyrokinin/PBAN class of neuropeptides, which features a 2-amino7-bromofluorene attached to the carboxy-terminal bioactive core of the insect pyrokinin/PBAN class of neuropeptides (Phe-Thr-Pro-Arg-Leu-NH(2)), via a succinnic acid linker, was tested in adult H. virescens moths. This analog was found to induce pheromone production when injected into or applied topically to moths. Topical application of as much as 1 nmol of the analog to moths induced production of significant amounts of pheromone for only 1-2 h, whereas injection of 500 pmol induced pheromone production for up to 20 h. All insects died within 24 h after injection of 500 pmol of the analog. Mortality studies indicated that the LD(50) for the analog was 0.7 pmol when injected. A non-pyrokinin/PBAN peptide analog formed by attachment of 2-amino-7-bromofluorene to Ala-Ala-Arg-Ala-Ala-NH(2) (via the succinnic acid linker) did not induce mortality when injected at 1 nmol. Similarly no mortality was found when up to 2 nmol of an analog containing a non-brominated fluorene ring, formed by attachment of 9-fluoreneacetic acid to Phe-Thr-Pro-Arg-Leu-NH(2,) was injected into moths. The data indicated that both the bromine and active core of the pyrokinin neuropeptides (Phe-Thr-Pro-Arg-Leu-NH(2)) were critical for a specific toxic action and suggested that the brominated analog poisoned the moths by interacting with pyrokinin receptors.

Animals↗
PubMed2000

Synthesis and PTP1B inhibition of novel 4-aryl-1-oxa-9-thiacyclopenta[b]fluorenes.

Novel 4-aryl-1-oxa-9-thiacyclopenta[b]fluorenes were designed, synthesized, and evaluated as inhibitors of the protein tyrosine phosphatase, PTP1B. Compounds 3 (IC50 = 284 nM) and 4 (IC50 = 74 nM), showed nanomolar potency against PTP1B (TRDI(P)YETD(P)Y(P)YRK as substrate). Compound 4 also lowered insulin in the diabetic ob/ob mouse at a dose of 10 mg/kg/day, p.o.

Amino Acid Sequence↗
PubMed1981

Mechanism of inhibition of enzymatic deoxyribonucleic acid methylation by 2-(acetylamino)fluorene bound to deoxyribonucleic acid.

Binding of 2-(acetylamino)fluorene (AAF) to C-8 of guanine induces a local destabilization of the DNA helix. A relationship was observed where the degree of DNA modification by AAF was inversely proportional to its methyl acceptor capacity from S-adenosyl-L-methionine in the presence of rat brain DNA cytosine 5-methyltransferase. Moreover, substituted DNA (DNA-AAF) behaves as a methylation inhibitor of native DNA. This inhibition is of the mixed type. The substituted DNAs have higher affinities for the enzyme than native DNA. The inhibition is irreversible. Addition of DNA-AAF to the enzyme preincubated with native DNA inhibits methylation, but only after a lag period. This agrees with the model in which the methylase "walks" along the strand to methylate cytosine residues before being detached from the DNA. AAF bound to guanine residues may block the movement of the enzyme along the helix. Single-stranded DNA has an affinity for the methylase 1.6 times lower than that of native double-stranded DNA. On the other hand, single-stranded DNA-AAF is more methylated than double-stranded DNA-AAF. A tentative model taking into account these observations is presented under Discussion. The in vitro hypomethylation of DNA-AAF could explain the in vivo observations made by several authors.

2-Acetylaminofluorene↗
PubMed1980

Binding of a tryptophan-containing peptide (lysyltryptophyllysine) to deoxyribonucleic acid modified by 2-(N-acetoxyacetylamino)fluorene.

The binding of the tripeptide Lys-Trp-Lys to DNA modified by reaction with the chemical carcinogen 2-(N-acetoxyacetylamino)fluorene (AAAF) has been investigated by fluorescence spectroscopy. A quenching of tryptophan fluorescence was observed which increased when the degree of base substitution by AAAF increased. Similar results were obtained with the 7-iodo derivative of AAAF (AAAIF). Two hypotheses are discussed which could account for the experimental results: (1) stacking interactions of the tryptophyl residue of the peptide with nucleic acid bases in locally unpaired regions in the vicinity of modified bases; (2) energy transfer from the tryptophyl residue of the peptide to acetylaminofluorene bound to guanine bases without direct interaction of this residue with nucleic acid bases (outside binding). The results obtained with denatured DNA in the absence and the presence of chemical modifications by AAAF or AAAIF allow us to conclude that energy transfer contributes to fluorescence quenching in the case of AAIF but not in that of AAF. Stacking interactions are therefore responsible for fluorescence quenching of Lys-Trp-Lys when bound to AAF-modified DNA. In the case of DNA-AAIF, fluorescence quenching is due both to energy transfer and to stacking of the tryptophan ring with bases inside the helix. These results are discussed in relation to what is already known in terms of local structure and with respect to the role that could be played by aromatic residues of proteins in the recognition of chemically damaged DNA.

2-Acetylaminofluorene↗
PubMed2005

(Fluoren-9-ylidene)methanedithiolato complexes of platinum: synthesis, reactivity, and luminescence.

Platinum(II) complexes with (fluoren-9-ylidene)methanedithiolato and its 2,7-di-tert-butyl- and 2,7-dimethoxy-substituted analogues were obtained by reacting different chloroplatinum(II) precursors with the piperidinium dithioates (pipH)[(2,7-R2C12H6)CHCS2] [R = H (1a), t-Bu (1b), or OMe (1c)] in the presence of piperidine. The anionic complexes Q2[Pt{S(2)C=C(C12H6R(2)-2,7)}2] [R = H, (Pr(4)N)(2)2a; R = t-Bu, (Pr4N)(2)2b, (Et4N)(2)2b; R = OMe, (Pr4N)(2)2c] were prepared from PtCl(2), piperidine, the corresponding QCl salt, and 1a-c in molar ratio 1:2:2:2. In the absence of QCl, the complexes (pipH)(2)2b and [Pt(pip)(4)]2b were isolated depending on the PtCl(2):pip molar ratio. The neutral complexes [Pt{S2C=C(C12H6R(2)-2,7)L(2)] [L = PPh(3), R = H (3a), t-Bu (3b), OMe (3c); L = PEt(3), R = H (4a), t-Bu (4b), OMe (4c); L(2) = dbbpy, R = H (5a), t-Bu (5b), OMe (5c) (dbbpy = 4,4'-di-tert-butyl-2,2'-bipyridyl)] were similarly prepared from the corresponding precursors [PtCl2L2] and 1a-c in the presence of piperidine. Oxidation of Q(2)2b with [FeCp2]PF6 afforded the mixed Pt(II)-Pt(IV) complex Q2[Pt2{S2C=C[C12H6(t-Bu)(2)-2,7]}4] (Q(2)6, Q = Et4N+, Pr4N+). The protonation of (Pr4N)(2)2b with 2 equiv of triflic acid gave the neutral dithioato complex [Pt2{S2CCH[C12H6(t-Bu)(2)-2,7]}4] (7). The same reaction in 1:1 molar ratio gave the mixed dithiolato/dithioato complex Pr4N[Pt{S2C=C[C12H6(t-Bu)(2)-2,7]}{S2CCH[C12H6(t-Bu)(2)-2,7]}] (Pr(4)N8) while the corresponding DMANH+ salt was obtained by treating 7 with 2 equiv of 1,8-bis(dimethylamino)naphthalene (DMAN). The crystal structures of 3b and 5c.CH2Cl2 have been solved by X-ray crystallography. All the platinum complexes are photoluminescent at 77 K in CH2Cl2 or KBr matrix, except for Q(2)6. Compounds 5a-c and Q8 show room-temperature luminescence in fluid solution. The electronic absorption and emission spectra of the dithiolato complexes reveal charge-transfer absorption and emission energies which are significantly lower than those of analogous platinum complexes with previously described 1,1-ethylenedithiolato ligands and in most cases compare well to those of 1,2-dithiolene complexes.

Journal Article↗
PubMed1998

Complexes of Strong Bidentate Lewis Acids Derived from 2,7-Bis(1,1-dimethylethyl)fluorene-1,8-diol.

Treatment of 2,7-bis(1,1-dimethylethyl)fluorene-1,8-diol (3) with 2 equiv of TiCl(4) converts the two OH groups into OTiCl(3) groups and thereby yields bis(trichlorotitanium phenoxide) 7, a structurally well-defined reagent that holds two sites of strong Lewis acidity in close proximity. Bidentate Lewis acid 7 forms a crystalline 1:2 complex with 4,4'-dimethylbenzophenone. An X-ray crystallographic study revealed that each atom of titanium binds only one molecule of ketone to form an unusual pentacoordinate adduct with an approximately trigonal bipyramidal geometry. Treatment of fluorenediol 3 with 2 equiv of Al(CH(2)CH(3))(3) does not yield the expected bis(diethylaluminum phenoxide) 8, but rather its dimer 9. Formation of diverse reagents 7 and 9 from the same precursor demonstrates that the strategy of converting organic compounds with suitably oriented hydroxyl groups into the corresponding metal alkoxides is a particularly versatile and effective way to make strong, structurally well-defined multidentate Lewis acids.

Journal Article↗