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PubMed1994

Exposure to phenoxyacetic acids, chlorophenols, or organic solvents in relation to histopathology, stage, and anatomical localization of non-Hodgkin's lymphoma.

Results on 105 cases with histopathologically confirmed non-Hodgkin's lymphoma (NHL) and 335 controls from a previously published case-control study on malignant lymphoma are presented together with some extended analyses. No occupation was a risk factor for NHL. Exposure to phenoxyacetic acids yielded, in the univariate analysis, an odds ratio of 5.5 with a 95% confidence interval of 2.7-11. Most cases and controls were exposed to a commercial mixture of 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid. Exposure to chlorophenols gave an odds ratio of 4.8 (2.7-8.8) with pentachlorophenol being the most common type. Exposure to organic solvents yielded an odds ratio of 2.4 (1.4-3.9). These results were not significantly changed in the multivariate analysis. Dichlorodiphenyltrichloroethane, asbestos, smoking, and oral snuff were not associated with an increased risk for NHL. The results regarding increased risk for NHL following exposure to phenoxyacetic acids, chlorophenols, or organic solvents were not affected by histopathological type, disease stage, or anatomical site of disease presentation. Median survival was somewhat longer in cases exposed to organic solvents than the rest. This was explained by more prevalent exposure to organic solvents in the group of cases with good prognosis NHL histopathology.

Acetates↗
PubMed2000

Mechanism of negative ion formation from phenol and para-chlorophenol by interaction with free electrons

Dissociative electron attachment (DEA) to phenol and para-chlorophenol in the energy range 0-12 eV is studied. Analogies in formation of the resonance states in an ionic benzene and its derivatives are found to arise from the similarity of the aromatic base of the molecules. Differences in DEA processes are defined mainly by the influence of the functional OH-group and, to a lesser degree, by the presence of a chlorine atom. A correlation between the energies of the resonance states and ionization energies of p-chlorophenol and phenol, analogous to that found previously for phenol, is proved. On this basis it is established that the dominating mechanism for formation of molecular negative ions at energies above 5 eV is Feshbach resonance.Copyright 2000 John Wiley & Sons, Ltd.

Journal Article↗
PubMed2004

Multi-criteria decision making in micellar liquid chromatographic separation of chlorophenols.

Simultaneous optimization of separation quality and analysis time of the micellar liquid chromatography of nine chlorophenol isomers was investigated. The effect on retention of three experimental parameters was studied using multivariate analysis. The factors studied were the concentration of sodium dodecyl sulfate, propanol content, and pH of the mobile phase. The experiments were performed according to the face-centered cube central composite design and the inverse form of the experimental retention times of analytes was fitted to polynomial models. The results of the analysis of variance showed that the models obtained explain over 99% of the variance observed in the chromatograms. The good predictive ability of the models was verified by high correlation coefficient (R2 > 0.99) and F ratio values for the plots of predicted cross-validated versus experimental retention times. The study showed that the use of the Pareto-Optimality method, an approach from multi-criteria decision making, allows selection of the best possible combinations of separation quality and analysis time in micellar liquid chromatography of chlorophenols.

Journal Article↗
PubMed1995

Chronic nephropathy and renal carcinogenicity of o-benzyl-p-chlorophenol in F344/N rats and B6C3F1 mice.

o-Benzyl-p-chlorophenol, an aryl halide biocide, was evaluated in male and female F344/N rats and B6C3F1 mice in a series of subchronic and 2-year toxicity and carcinogenicity studies. Kidney was the primary target of toxicity in the 13-week gavage studies in rats and mice, with increased nephropathy noted as low as 240 mg/kg in male rats. Considering the nephropathy to be doselimiting, the chronic (2-year) study was conducted at lower doses (male rats: 30, 60, or 120 mg/kg; female rats: 60, 120, or 240 mg/kg; male and female mice: 120, 240, or 480 mg/kg; in corn oil; n = 50/group). Survival and body weights of dosed rats were similar to controls in the 2-year study. Survival of high-dose male and female mice, and body weights of all dosed male and mid- and high-dose female mice, were lower than controls. The incidence and severity of nephropathy increased with dose and length of treatment in both rats and mice. There was an increased incidence of renal tubule adenomas or carcinomas in both the mid- and high-dose male mice. Despite similar evidence of nephropathy, however, there were no increased incidences of neoplasms in female mice or in male or female rats. This study suggests therefore that while nephrotoxicity may have been a necessary component, factors other than the marked nephrotoxicity of o-benzyl-p-chlorophenol were critical to the development of renal carcinogenesis induced in only male mice.

Adenoma↗
PubMed2005

Displacement imprinted polymer receptor analysis (DIPRA) for chlorophenolic contaminants in drinking water and packaging materials.

The preparation of a molecularly imprinted polymer (MIP) for pentachlorophenol is described together with two alternative reporter derivatives for use in a displacement imprinted polymer receptor analysis (DIPRA) format procedure. In this procedure, alternative reporter molecules were rebound to the synthetic receptor sites and their displacement by the target analyte was employed as the basis of a simple procedure for the measurement of chlorophenols in water and packaging material samples. Water samples were extracted using the standard procedure (EPA 528) and a detection limit of 0.5 microg l(-1) was achieved using the DIPRA detection method, with good agreement between the displacement technique and GC-ECD analysis. A variety of packaging materials, extracted using a buffered detergent solution were also analysed using the DIPRA procedure and showed good agreement with GC results. In addition, investigation of the cross-reactivity of a range of pesticides and materials commonly encountered in environmental analysis indicated the procedure gave good discrimination between pesticides bearing a chlorophenolic moiety and other materials. The procedure is considered highly suitable for use as a rapid field-test method or for incorporation into a test kit device.

Food Analysis↗
PubMed2005

Ecotoxicological evaluation of the biocidal agents sodium o-phenylphenol, sodium o-benzyl-p-chlorophenol, and sodium p-tertiary amylphenol.

The ecotoxicological effects of three biocidal agents frequently employed as active ingredients in phenolic-based disinfectants were evaluated using a test battery comprising of organisms representing three aquatic trophic levels. Phenolic-based disinfectants are commonly used by mushroom growers to disinfect spent mushroom compost. In general, the most sensitive assay used in this study was the Microtox test. In the case of the fish lethality assay, sodium o-benzyl-p-chlorophenol was found to be slightly more sensitive than the bacterial test system. The freshwater alga and invertebrate tests were also among the most sensitive test species employed. The active ingredient, sodium o-benzyl-p-chlorophenol (with the exception of the Microtox assay), was the most toxic chemical tested on each species. The majority of ecotoxicity data obtained in this research has not been previously reported and may therefore assist in the management and planning decisions regarding the application of pesticides and utilisation of SMC.

Agaricales↗
PubMed2006

In vitro cytotoxicity assessment of the biocidal agents sodium o-phenylphenol, sodium o-benzyl-p-chlorophenol, and sodium p-tertiary amylphenol using established fish cell lines.

The cytotoxicity of three biocidal agents frequently employed as active ingredients in phenolic-based disinfectants, were evaluated in three established fish cell lines (EPC, CHSE and RTG-2). Cell viability was assessed using two fluorescent indicator dyes, Alamar Blue for metabolism and neutral red for lysosomal activity. Total protein content was also quantified as a measure of cell detachment. In order to evaluate the sensitivity of the cell cultures, the results obtained were compared with toxicity data obtained from a previous study with the same three compounds and the in vivo lethality test with rainbow trout. Results from this study established that each of the three cell lines ranked the tested chemicals in the same order of toxicity as the in vivo test; however, the cell cultures were found to be an order of magnitude less sensitive than whole fish studies with the same compounds. The chemical sodium o-benzyl-p-chlorophenol was consistently ranked the most toxic of the tested compounds with each cell line and the endpoints employed. The rank order of toxicity was always sodium o-benzyl-p-chlorophenol > sodium p-tertiary amylphenol > sodium o-phenylphenol. The EPC cells were found to be the most sensitive cell line tested based on Alamar Blue IC(50) data, and the Alamar Blue assay was consistently found to be the most sensitive endpoint of the three cytotoxicity assays employed.

Animals↗
PubMedDate not supplied

Temperature dependence of DCDD/F isomer distributions from chlorophenol precursors.

The temperature dependence of the gas-phase, rate-limited formation of dichlorodibenzo-p-dioxin (DCDD) and dichlorodibenzofuran (DCDF) isomers from 2,6-dichlorophenol and 3-chlorophenol, respectively, has been studied experimentally in an isothermal flow reactor over the range 300-900 degrees C under pyrolytic, oxidative and catalytic conditions and computationally using semi-empirical molecular orbital methods. At high temperatures, distributions of sets of DCDD/F condensation products are consistent with the calculated thermodynamic distributions, indicating that the relative rates of formation are governed by differences in symmetry and steric hindrance present in the isomer product structures. At low temperatures, however, this is not the case. In the case of 1,6- and 1,9-DCDD formed from 2, 6-dichlorophenol via Smiles rearrangement, the 1,6 isomer is favored at low temperatures more than thermodynamically predicted. This result appears to be consistent with kinetic effects of either the expansion of the five-membered ring Smiles intermediate or a lower activation energy six-membered ring intermediate pathway that produces only the 1,6 isomer. For formation of 1,7-, 3,7- and 1,9-DCDF from 3-chlorophenol, the 1,7 isomer fraction increases at low temperatures whereas thermodynamics predicts a decrease. This result can be attributed to steric effects in alternative "sandwich-type" approach geometries of phenoxy radicals to form the o,o'-dihydroxybiphenyl (DOHB) intermediate via its keto-tautomers. Higher level molecular theory (ab initio) is needed to provide a more quantitative description of these kinetics.

Journal Article↗
PubMed2001

Dechlorination of chlorophenols using extracellular peroxidases produced by streptomyces albus ATCC 3005.

Streptomyces albus ATCC 3005 was found to produce higher levels of extracellular peroxidase activity (3.420 U mg(-1)) than previously reported for any other actinomycete. Maximum peroxidase activity was obtained after 72 h of incubation at a temperature of 30 degrees C in a liquid medium (pH 7.6) containing (in w/v) 0.8% to 0.9% oat spelts xylan and 0.6% yeast extract, corresponding to a C:N ratio of around 8.4:1. Characterization of the peroxidases revealed that the optimal temperature for peroxidase activity, using the standard 2,4-dichlorophenol (2,4-DCP) assay was 53 degrees C, when the enzyme reaction was performed at pH 7.2. A study of the effect of temperature on the stability of peroxidase over time, showed that the enzyme was stable at 40 degrees C, with a half-life of 224 min, while at higher temperatures the stability and activity was reduced such that at 50 degrees C and 70 degrees C the half-life of the enzyme was 50 min and 9 min respectively. The optimum pH for the activity of the enzyme occurred between pH 8.1 and 10.4. In terms of substrate specificity, the peroxidase was able to catalyze a broad range of substrates including 2,4-DCP, L-3,4-dihydroxyphenylalanine (L-DOPA), 2,4,5-trichlorophenol and other chlorophenols in the presence of hydrogen peroxide. Ion exchange chromatography was used to confirm that the enzyme was able to release chloride ions from a range of chlorophenols.

Journal Article↗
PubMed2000

Fiber optic monitoring of carbamate pesticides using porous glass with covalently bound chlorophenol red.

An optical fiber biosensor for the determination of the pesticides propoxur (Baygon) and carbaryl, two of the most commonly used carbamate insecticides in vegetable crops, is described. A pH indicator, chlorophenol red, is used as optical transducer of the inhibition of the enzyme acetylcholinesterase by the analytes. The biorecognition element is covalently immobilized onto controlled pore glass beads (CPG) and packed in a thermostatized bioreactor connected to a flow-through cell that contains CPG-immobilized chlorophenol red placed at the common end of a bifurcated fiber optic bundle. In the presence of a constant acetylcholine concentration, the colour of the pH sensitive layer changes and the measured reflectance signal can be related to the carbamate concentration in the sample solution. The performance of the biosensor has been optimized using a flow injection system. The linear dynamic range for the determination of carbaryl and propoxur spans from 0.8 to 3.0 mg l(-1) and from 0.03 to 0.50 mg l(-1), respectively. The detection limit (3 s) of the biosensor for propoxur (0.4 ng) is lower than that measured for carbaryl (25 ng). Reproducibility, stability and interference studies of the optical device are reported. The biosensor has been applied to the determination of propoxur in spiked vegetables (onion and lettuce) using ultrasound extraction, achieving recovery values between 93 and 95% for onion samples at the different concentration levels assayed.

Acetylcholine↗
PubMed2006

Impact of iron-complex (Fe(III)-NTA) on photoinduced degradation of 4-chlorophenol in aqueous solution.

In this research work, the photochemical impact of Fe(III)-nitrilotriacetic acid complex (FeNTA) on the fate of an organic pollutant (4-chlorophenol (4-CP)) was investigated in natural waters. The quantum yields of the photodecomposition of the FeNTA complex and of Fe(II) formation, by an intra-molecular photoredox process (the first stage of the reaction) are high. This photoredox reaction represents the first step of the process leading to 4-CP disappearance. Whereas oxygen does not affect FeNTA photodegradation, 4-CP depletion requires the presence of oxygen. The radical species HO and CO3*- responsible of the degradation were identified by ESR spectroscopy under irradiation. Two different wavelength-dependent mechanisms of 4-chlorophenol degradation are proposed. It clearly appears that under solar irradiation, iron organic complexes like FeNTA can play a significant role on the fate of the organic compounds present in natural waters.

Journal Article↗
PubMed1999

Hydroxylation reaction catalyzed by the Burkholderia cepacia AC1100 bacterial strain. Involvement of the chlorophenol-4-monooxygenase.

The Burkholderia cepacia AC1100 strain, known to degrade the herbicide, 2,4,5-Trichlorophenoxyacetic acid (2,4,5-T), is able to metabolize 4-hydroxyarylaldehyde, not only into the corresponding acid, but also into a new hydroquinone, 2,5-dihydroxyarylaldehyde. When incubated with resting AC1100 cells or cell-free extracts, syringaldehyde and 3,5-dimethoxy-4-hydroxybenzaldehyde were converted into such metabolites, identified by comparison of their mass and 1H-NMR spectra with those of authentic chemically synthesized samples. With 5-bromovanillin, only one metabolite was formed, the structure of which was identified as 2, 5-dihydroxy-4-methoxy-6-bromobenzaldehyde through 1H-NMR two-dimensional NOESY experiments. All these products result formally from a para hydroxylation of the phenol followed by the cis migration of the aldehyde. This reaction is the only one to be associated with the 2,4,5-T degradation pathway, as the acid formation was retained when the AC1100 strain had lost its degradation ability. Through competitive experiments with halophenols and methimazole, an alternative substrate of flavin monooxygenase, the chlorophenol-4-monooxygenase was recognized to be the enzyme involved in the hydroxylation of 4-hydroxyarylaldehyde. The purified enzyme, previously reported to catalyze the para hydroxylation or dehalogenating hydroxylation of chlorophenols, also promotes this hydroxylation reaction in the presence of NADH and FAD. The kcat value determined for the best substrate, syringaldehyde, 0. 08 s-1, was about 20% of that obtained for 2,6-dichlorophenol hydroxylation (0.38 s-1).

Aldehydes↗
PubMed1999

Self-assembly of chlorophenols in water.

In saturated solutions of some di- and trichlorophenols, structures with complex morphologies, consisting of thin, transparent sheets often coiling into helices and ultimately twisting into filaments, were observed under the optical microscope. Freeze-fracture electron microscopy, x-ray diffraction, phase diagrams, and molecular modeling were performed to elucidate the observed phenomena. Here, we present evidence that the chlorophenols studied, when interacting with water, self-assemble into bilayers. The fact that some chlorophenols form the same supramolecular structures as those described previously for structurally nonrelated surfactants sheds light on the mechanisms of self-assembly.

Journal Article↗
PubMed1994

Regiospecificity of chlorophenol reductive dechlorination by vitamin b(12s).

Vitamin B(12), reduced by titanium (III) citrate to vitamin B(12s), catalyzes the reductive dechlorination of chlorophenols. Reductive dechlorination of pentachlorophenol and of all tetrachlorophenol and trichlorophenol isomers was observed. Reaction of various chlorophenols with vitamin B(12) favored reductive dechlorination at positions adjacent to another chlorinated carbon, but chlorines ortho to the hydroxyl group of a phenol were particularly resistant to reductive dechlorination, even if they were also ortho to a chlorine. This resulted in a reductive dechlorination pattern favoring removal of para and meta chlorines, which differs substantially from the pattern exhibited by anaerobic microbial consortia.

Journal Article↗
PubMed1995

Two-Dimensional Gel Electrophoresis Analysis of the Response of Pseudomonas putida KT2442 to 2-Chlorophenol.

The effects of exposure of Pseudomonas putida KT2442 to 2-chlorophenol as a model for the chemical stress response were examined by two-dimensional polyacrylamide gel electrophoresis. Individual protein concentrations were determined at 45, 65, and 95 min following the addition of 2-chlorophenol at a concentration of 1.63 mM to exponentially growing cultures of P. putida KT2442 by silver staining the separated proteins. The changes in the protein concentrations could be classified into four categories, namely those which increased continuously during exposure, those which decreased in concentration, those which showed a concentration peak at some point following exposure, and those which were essentially unaffected. Thirty proteins with isoelectric points between pH 4 and 6 increased in concentration, 27 decreased, and 90 had a concentration maximum or minimum between 45 and 95 min. Of those proteins with isoelectric points between 5.5 and 10, 68 increased in concentration, 39 decreased in concentration, and 47 showed a concentration peak in the middle of the sampling period. Thus, in the evaluation of the stress response, a functional description requires an understanding both of proteins which are required at higher concentrations and of those whose presence appears to be no longer essential.

Journal Article↗
PubMed2000

Transcriptional regulation of the cpr gene cluster in ortho-chlorophenol-respiring Desulfitobacterium dehalogenans.

To characterize the expression and possible regulation of reductive dehalogenation in halorespiring bacteria, a 11.5-kb genomic fragment containing the o-chlorophenol reductive dehalogenase-encoding cprBA genes of the gram-positive bacterium Desulfitobacterium dehalogenans was subjected to detailed molecular characterization. Sequence analysis revealed the presence of eight designated genes with the order cprTKZEBACD and with the same polarity except for cprT. The deduced cprC and cprK gene products belong to the NirI/NosR and CRP-FNR families of transcription regulatory proteins, respectively. CprD and CprE are predicted to be molecular chaperones of the GroEL type, whereas cprT may encode a homologue of the trigger factor folding catalysts. Northern blot analysis, reverse transcriptase PCR, and primer extension analysis were used to elucidate the transcriptional organization and regulation of the cpr gene cluster. Results indicated halorespiration-specific transcriptional induction of the monocistronic cprT gene and the biscistronic cprBA and cprZE genes. Occasional read-through at cprC gives rise to a tetracistronic cprBACD transcript. Transcription of cprBA was induced 15-fold upon addition of the o-chlorophenolic substrate 3-chloro-4-hydroxyphenylacetic acid within 30 min with concomitant induction of dehalogenation activity. Putative regulatory protein binding motifs that to some extent resemble the FNR box were identified in the cprT-cprK and cprK-cprZ intergenic regions and the promoter at cprB, suggesting a role for FNR-like CprK in the control of expression of the cprTKZEBACD genes.

Amino Acid Sequence↗
PubMed2002

Use of disposable GRC electrodes for the detection of phenol and chlorophenols in liquid chromatography.

In this study, a wall-jet flow cell with a GRC (graphite reinforced by carbon) electrode was designed for the amperometric detection of phenol and chlorophenols in liquid chromatography. The voltammetric responses of these analytes at the GRC electrodes are very similar to those at conventional glassy carbon electrodes. As the GRC electrodes were made of the same materials as commercially available mechanical pencil leads, they exhibit the advantages of low cost, simple surface renewability, lower residual current, and good electrode-to-electrode reproducibility, and thus can be used as disposable-type electrodes. Chromatographic separations of phenol, o-chlorophenol (o-CP), 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP), and pentachlorophenol (PCP) were achieved with an ODS column using a mobile phase containing a mixture of CH3CN and H20 (40:60) containing 25 mM L-(+)tartaric acid (pH = 4.5). Amperometric detections were based on the electrochemical oxidation of these compounds around +0.9 V vs. Ag/AgCl. Under the optimized conditions, linear calibrations were obtained in a range up to 100 microM for phenol, o-CP, 2,4-DCP, 2,4,6-TCP, and 200 microM for PCP, with the correlation coefficients r2 of 0.9992, 0.9997, 0.9986, 0.9992, and 0.9968, respectively. The chromatographic detection limits for the tested analytes were obtained at pmol levels.

Journal Article↗
PubMed2003

[The high-sensitivity determination of protein concentration by the enhancement of resonance light scattering of chlorophenol red].

A new resonance light scattering (RLS) assay is presented in this paper. At the optimum pH = 4.0, the weak RLS of chlorophenol red can be greatly enhanced by the addition of proteins due to the interaction between protein and chlorophenol red. A new quantitative determination method for proteins has been developed. The linear range is 0-1.0 mg.L-1 for BSA, and 0-0.75 mg.L-1 for HSA with detection limit of 20.3 micrograms.L-1 for BSA, and 20.4 micrograms.L-1 for HSA, respectively. Besides high sensitivity, the method is characterized by good reproducibility, rapidity of reaction, good stability and few inferring substances. The determination results of the proteins in human serum samples by this method are very close to those obtained using biuret spectrophotometric method, with relative stand deviation of 1.17%-2.42%.

Animals↗