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At least 523 records · Page 29Linked to original sources
PubMed2006

Dioxygenation of naphthalene by Pseudomonas fluorescens N3 dioxygenase: optimization of the process parameters.

The bioconversion of naphthalene to the 1,2-dihydro-1,2-dihydroxy derivative was performed in good yield using an Escherichia coli recombinant strain carrying Pseudomonas fluorescens N3 dioxygenase. However, the efficiency of such transformation is affected by many process parameters, and their optimization is essential to the scaling up of the process. The following process parameters were considered for optimization: cell concentration together with the corresponding glucose concentration (DCW/L); pH of medium; temperature; stirring speed; air flow; substrate concentration; Fe(2+) concentration; microelements concentration; reaction volume. We used a two-step multivariate experimental design to select important variables and assign them optimal values. The most significant parameters were selected by adopting a Plackett-Burman design, and were then correlated, using a full factorial design, with the experimental results. The experimental results illustrate that the optimized process of recombinant whole cell biotransformation in two-liquid phase systems enhances the naphthalene dihydrodiol yield threefold. This biotransformation opens the way to future experiments involving different substrates.

Bacterial Proteins↗
PubMed2004

Singlet excited-state interactions in naphthalene-thymine dyads.

Two thymidine-derived nucleosides 1 and 2 were prepared by attaching a chiral naphthalene to the positions 5' and 3' of the sugar. The resulting dyads, which contain key substructures present in drugs and nucleic acids, exhibit different spatial arrangements (transoid or cisoid) of the fluorophore relative to the thymine unit. Emission measurements on these compounds in the presence of ROH molecules revealed a remarkable intramolecular prescence quenching for dyad 1. The obtained results are consistent with quenching of the singlet excited state of 1 by hydrogen-bond donor solvents. Thus, a physical deactivation process (vibronically induced internal conversion) would be the pathway responsible for the accelerated decay of 1*, favorably competing with fluorescence and intersystem crossing to the triplet. This effect appears to be strongly dependent on the relative spatial arrangement between the naphthalene and thymine units, together with the hydrogen-bonding ability of the employed ROH.

Crystallography, X-Ray↗
PubMedDate not supplied

Haemolytic anaemia after oral self-giving of naphthalene-containing oil.

A clinical case of suicide attempt by means of oral self-giving of naphthalene-containing oil in an old man was reported. Clinical features showed haemolytic anaemia supported by a decrease of haemoglobin concentration and red blood cell count, an increase of bilirubin (prevalently indirect) and lactate dehydrogenase and very low levels of haptoglobin. Methaemoglobin (metHb) measured at admission to the Emergency Room and 19 days after poisoning was still above normal limits. No deficiency of glucose-6-phosphate dehydrogenase was detected. The clinical manifestations ameliorated after treatment with concentrated red blood cells and ascorbic acid, with fast normalization of metHb. The clinical picture appeared almost normal 1 month after poisoning. The clinical diagnosis was 'haemolytic anaemia caused by naphthalene'. Absence of glucose-6-phosphate dehydrogenase deficiency probably reduced the severity of poisoning.

Administration, Oral↗
PubMed1986

Oxidation of naphthalene by Saccharomyces cerevisiae and Candida utilis.

The yeasts Saccharomyces cerevisiae 118 and Candida utilis 128 were examined for their ability to metabolize the polycyclic aromatic hydrocarbons naphthalene and anthracene. The two yeasts tested oxidized these aromatics. Metabolites were extracted and analyzed by thin layer chromatography and gas chromatography. The predominant oxidation product of naphthalene found in the culture medium was 1-naphthol.

Anthracenes↗
PubMed1984

Expanded solubility parameter approach. I: Naphthalene and benzoic acid in individual solvents.

An expanded solubility parameter system was tested in conjunction with the extended Hansen solubility approach and the UNIFAC method to calculate the solubilities of naphthalene and benzoic acid in polar and nonpolar solvents. The expanded parameter system is characterized by delta d for the dispersion force, delta p for dipolar forces, a basic or electron-donor parameter, delta b, and an acidic or electron-acceptor parameter delta a. The correlation between the calculated and observed solubilities of benzoic acid was increased by use of the four-parameter system. An indicator variable was required to bring the solubilities into line in strongly dipolar solvents such as N,N-dimethylformamide. For naphthalene, use of the four-parameter approach proved not to be an improvement over the three-parameter extended Hansen solubility approach. The UNIFAC method was not successful in calculating solubilities of benzoic acid in the 40 polar and nonpolar solvents. A triangular plot of the three Hansen parameters for benzoic acid, p-hydroxybenzoic acid, and methyl p-hydroxybenzoate illustrated the contributions of dispersion, dipolar, and Lewis acid-base (hydrogen bonding) interaction forces among the three benzoic acid compounds and the various classes of solvents. A multiple regression procedure for calculating the four partial solubility parameters of drug solutes was developed.

Benzoates↗
PubMed1998

Cloning and expression of CYP2F3, a cytochrome P450 that bioactivates the selective pneumotoxins 3-methylindole and naphthalene.

Members of the CYP2F gene subfamily are selectively expressed in lung tissues and have been implicated as important catalysts in the formation of reactive intermediates from several pneumotoxic chemicals. Human CYP2F1 bioactivates 3-methylindole (3MI), while mouse CYP2F2 bioactivates naphthalene. Although 3MI is a potent pneumotoxin in ruminants and rodents, the participation of cytochrome P450s from the 2F subfamily in 3MI bioactivation has not been fully defined. To test the hypothesis that a goat lung 2F homologue uniquely catalyzes the dehydrogenation of 3MI to the putative electrophile 3-methylene-indolenine, the CYP2F3 cDNA was cloned from a goat lung cDNA library and expressed in Escherichia coli. The predicted amino acid sequence of CYP2F3 possessed 82% identity to both human CYP2F1 and mouse CYP2F2. CYP2F3 was mutated at the 5' end, expressed in E. coli, and shown to have a molecular mass of 50 kDa. The reconstituted enzyme uniquely catalyzed only the dehydrogenation of 3MI to form 3-methylene-indolenine, an electrophilic intermediate, without detectable formation of other products, thus demonstrating highly unusual selectivity for dehydrogenation rather than hydroxylation of a substrate. Immunoinhibition studies demonstrated that about 20% of the production of the intermediate in goat lung microsomal samples was produced by CYP2F3. The CYP2F3 enzyme had a specific activity that was similar to that of human cDNA-expressed CYP2F1. CYP2F3 also stereoselectively catalyzed the formation of the 1R,2S-oxide from naphthalene; this stereoisomer is the putative pneumotoxin. The enzyme, however, lacked catalytic activity with other common P450 substrates including 7-ethoxycoumarin, a substrate for CYP2F1, indicating that the substrate selectivity of CYP2F3 appears to be high.

Amino Acid Sequence↗
PubMed2000

Substrate binding site of naphthalene 1,2-dioxygenase: functional implications of indole binding.

The three-dimensional structure of the aromatic hydroxylating enzyme naphthalene dioxygenase (NDO) from Pseudomonas sp. NCIB 9816-4 was recently determined. The refinement of the structure together with cyclic averaging showed that in the active site of the enzyme there is electron density for a flat aromatic compound. This compound appears to be an indole adduct, which in Escherichia coli is derived from tryptophan present in the rich culture medium. An indole-dioxygen adduct has been built which fits the electron density convincingly. Support for this interpretation was obtained from crystals of the enzyme purified from cells grown in the absence of tryptophan which had an empty substrate pocket. These types of crystals were soaked in indole solutions and the position of indole in this complex was similar to the corresponding part in the modelled indole-oxygen adduct. This suggests that a peroxide bound to iron end-on attacks the substrate and forms this intermediate. The substrate position has implications for the substrate specificity of the enzyme. Docking studies with indole, naphthalene and biphenyl inside the substrate pocket of NDO suggest the presence of subpockets where the one close to the active site iron is reserved for the binding of the aromatic ring which is hydroxylated upon catalysis. The plausible location for the binding of dioxygen is between this pocket and the catalytic iron. This is in accordance with the enantiospecificity of the products.

Amino Acid Sequence↗
PubMed1984

Synthesis, characterization and biologic effects of polybrominated naphthalenes.

Although polybrominated naphthalenes (PBNs) are contaminants of the commercial fire retardant fireMaster BP-6, the individual PBN isomers have not been identified. In order to study PBNs possessing an analogous level of bromination to those found in fireMaster BP-6, three synthetic PBN mixtures, averaging 5.0, 5.3, and 5.6 bromines per naphthalene were synthetized and partially characterized. The PBN mixtures were administered to immature male Wistar rats and found to be potent inducers of cytochrome P-450-dependent monooxygenases. At the lowest dose tested, 30 mumol X kg-1, each PBN mixture caused maximal induction of benzo[a]pyrene hydroxylase activity. On the basis of enzyme activities, ligand-binding spectra and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the PBN mixtures were determined to be 3-methylcholanthrene-type inducers of cytochrome P-450 (P-448), resembling qualitatively the most toxic polyhalogenated biphenyls, dibenzofurans, and dioxins in this respect. Liver weights were significantly increased and thymus weights diminished by PBN treatment. Light microscopy revealed proliferation of the smooth endoplasmic reticulum in periportal hepatocytes as a consistent change; some rats also had mild fatty changes in centrilobular hepatocytes. Thymuses displayed mild to marked depletion of cortical lymphocytes. The PBN mixtures were much more potent than fireMaster BP-6 in causing these effects; raising the possibility that PBNs are among the minor components of fireMaster BP-6 that contribute significantly to the toxicity of this environmental contaminant.

Animals↗
PubMed1982

Accumulation of 14C-Naphthalene in the tissues of redhead ducks fed oil-contaminated crayfish.

Crayfish, artificially contaminated with 14C-naphthalene-5% water-soluble fraction of No. 2 fuel oil, were force-fed to one-year-old redhead ducks to determine the accumulation of petroleum hydrocarbons. The relative distribution of carbon-14 activity in the gall bladder containing bile, and fat were similar, and significantly greater (P less than 0.05) than the activity in the blood, brain, liver, and kidney. There was a significant increase (P less than 0.05) in the disintegrations per minute per gram (dpm/g) in the blood, brain, kidney, and liver between days 1 and 3 of feeding, indicating a progressive accumulation of carbon-14 activity (naphthalene and presumably its metabolites). There was no significant effect of sex or the interaction of the duration of feeding and sex on carbon-14 activity in any of the tissues. The low daily dose of petroleum hydrocarbons (a total of approximately 1.25 mg/day) received by the ducks from the crayfish and the relatively short feeding regimen did not cause any overt signs of toxicity in the ducks.

Animal Feed↗
PubMed1986

Investigations on rat eyes with diabetic cataract and naphthalene cataract by Zeiss-Scheimpflug measuring system SLC.

Experimental cataract development can be objectively monitored in rats by Scheimpflug slit-image photography and microdensitometric image analysis. Zeiss (Oberkochen, Federal Republic of Germany) has developed a new computerized slit-lamp measuring system that works according to the Scheimpflug principle; we have very successfully applied it to rats with streptozotocin-induced cataracta diabetica vera and with naphthalene-induced opacities. With these cataract models we tested the gyrase inhibitor compound, Ciprofloxacin (Bayer 09867), after 6 weeks' daily peroral application (20 mg/kg body weight) for differences in cataract progression indicating a possible cocataractogenic effect of the compound. When we compared the two different Scheimpflug methods, we found that the Zeiss-Scheimpflug measuring system SLC has some handling advantages with respect to animal cataract studies. If the equipment is to be fully used, complements to the program of the integrated computer part are necessary. The image-analytical results from the animals treated with Ciprofloxacin did not show any indication of cocataractogenic potential with respect to cataracta diabetica vera or naphthalene cataract.

Animals↗
PubMed1996

Assessment of the impact of naphthalene contamination on mangrove fauna using behavioral bioassays.

Pollution of the marine and estuarine environments by petroleum hydrocarbons is a world wide phenomenon (Connell and Miller 1980) and whilst large scale crude oil spills are the most obvious source of pollution, since the 1970's the impact of chronic, low level hydrocarbon input from sources such as oil refineries has been recognised as having long term ecological consequences, even when there may be no visible evidence of acute effects (Connell and Miller 1980). Mangroves are perhaps the dominant and most important intertidal habitat along subtropical and tropical coastlines and estuaries and as such are located in areas of high risk of acute or chronic petroleum hydrocarbon pollution. Further, once contamination occurs, high levels of hydrocarbons may be expected to remain in mangrove sediments as conditions are not favorable for hydrocarbon depletion by sediment transport or degradation by aerobic bacteria. Much research has focused on determining the acute toxicity of the water soluble fraction of crude or fuel oil to aquatic fauna but relatively little attention has been given to individual hydrocarbons. The medium to low boiling point aromatics such as naphthalene and its alkyl derivatives are the most toxic petroleum fraction to marine organisms (Anderson et al. 1974; Moore and Dwyer 1974) and they are known to provoke behavioral responses in marine animals at sublethal concentrations (Hargrave and Newcomb 1973; Linden 1977; Nagarajah et al. 1985). The goal of this investigation was to investigate the effects of a single aromatic petroleum hydrocarbon, naphthalene, in a subtropical mangrove environment, through the use of behavioral bioassays. The test organism chosen was the intertidal gastropod Ophicardelus quoyi, which is abundant in mangroves throughout eastern Australia.

Animals↗
PubMed1995

Formation of epoxide and quinone protein adducts in B6C3F1 mice treated with naphthalene, sulfate conjugate of 1,4-dihydroxynaphthalene and 1,4-naphthoquinone.

Naphthalene (NA) is metabolically activated to the reactive intermediates, naphthalene oxide (NO) and naphthoquinones. To investigate the role of circulating reactive metabolites in NA toxicity, the half-life of NO was examined. The in vitro half-life of NO in both whole blood and plasma was 10 min. Detectable levels of NO were seen in perfusate leaving the isolated perfused liver of B6C3F1 mice infused with 10 mumol/h NA. Identification of protein sulfhydryl adducts in NA-exposed mice (50 and 100 mg/kg, IP, 24 h) revealed a predominance of quinone adducts in liver, lung, kidney, red blood cells and brain. The epoxide adduct predominated in plasma protein. Administration of the sulfate conjugate of 1,4-dihydroxynaphthalene (NHQS) (100 mg/kg) resulted in formation of naphthoquinone protein sulfhydryl adducts in lung, liver and kidney. Administration of 1,4-naphthoquinone (NQ) (5 mg/kg) produced NQ adducts in liver, lung, kidney, plasma and brain.

Animals↗
PubMed2000

Relative potencies of individual polychlorinated naphthalenes to induce dioxin-like responses in fish and mammalian in vitro bioassays.

A growing body of evidence suggests that polychlorinated naphthalenes (PCNs) may be fairly widespread environmental contaminants. This may be cause for concern because exposure to PCNs has been linked to dioxin-like biological responses in a wide variety of species. This study used three in vitro bioassays to characterize the dioxin-like potency of 18 individual PCN congeners and 1 PCN metabolite. The PLHC-1 fish hepatoma cell bioassay was relatively insensitive to PCNs. At the concentrations tested, only 1, 4 di-CN and 2,4-dichloro-1-napthol caused significant induction of ethoxyresorufin O-deethylase (EROD) activity in the PLHC-1 assay. In vitro EROD and luciferase assays using recombinant H4IIE rat hepatoma cells were more responsive to PCNs. Structure-activity relationships were observed both in terms of the degree of chlorination and the positions of chlorine substitutions. Hexa-chlorinated naphthalenes (CNs), exhibiting relative potencies (REPs) around 10(-3) (relative to TCDD), were the most potent congeners tested. Penta-CNs were also rather potent, yielding REPs between 10(-3) and 10(-7). Tetra-, tri-, di-, and mono-CNs were less active. REPs for the active congeners were similar to those for some PCBs. The relative potency estimates reported here contribute to an emerging body of information that will aid determination of the relative contribution of PCNs to the total dioxin-like activity associated with environmental samples.

Animals↗
PubMed1998

Polychlorinated naphthalenes and other organochlorine contaminants in Swedish human milk, 1972-1992.

The concentrations of polychlorinated naphthalenes (PCNs) were determined together with polychlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), 1,1-bis-(4-chlorophenyl)-2,2,2-trichloroethane (p,p'-DDT), 2,2-bis(4-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE) and hexachlorobenzene (HCB) in milk, sampled in the course of 1972-92 from mothers living in Stockholm. A previously developed method for multicomponent analysis of organochlorine environmental contaminants was adapted for simultaneous analysis of PCNs. The mean recoveries of seven chlorinated naphthalene (CN) congeners added to milk prior to extraction were 76-99%. Similar recoveries were obtained for the commercial PCN product Halowax 1014. The pattern of PCNs in milk differed to a great extent from that in the commercial PCN products. The dominating congeners in breast milk were 1,2,3,5,7-pentachloronaphthalene (CN-52), 1,2,3,4,6,7- and/or 1,2,3,5,6,7-hexachloronaphthalene (CN-66/ CN-67) and one unidentified tetrachloronaphthalene. There was a notable decrease in the concentrations of PCNs as was of the other organochlorine contaminants in milk from 1972 to 1992. During this time period the sum of CN congeners decreased from 3,081 to 483 pg/g milk fat and the sum of toxic equivalents of dioxin and dioxin-like compounds decreased from 100 to 39 pg/g milk fat.

Benzofurans↗
PubMed2003

Naphthalene-utilizing and mercury-resistant bacteria isolated from an acidic environment.

Soil samples were taken from areas of low pH (2.5-3.5) surrounding an outdoor coal storage pile. These samples were added to medium with naphthalene as the sole carbon source to enrich for organisms capable of degrading polycyclic aromatic hydrocarbons (PAH) at low pH. Five such bacterial strains were isolated. Sequencing of the 16S rDNA showed them to be members of the genera Clavibacter, Arthrobacter and Acidocella. These organisms were all capable of growth with naphthalene as a sole carbon source at low pH. The genes nahAc, nahAd, phnAc, nahH, xylE or GST, which are known to be associated with PAH degradation were not detected. Isolate 10, the Acidocella strain, tolerated high levels of mercury. PCR amplification and sequencing of genes from the mer operon from isolate 10 DNA suggested that mercury is transported into the bacterial cell and subsequently detoxified since the enzymes encoded by genes in this operon are involved in these processes.

Acetobacteraceae↗
PubMed2001

Efficiency of naphthalene and salicylate degradation by a recombinant Pseudomonas putida mutant strain defective in glucose metabolism.

Metabolically engineered microorganisms may have tremendous potential in removing toxic compounds from nature. In general, microorganisms prefer to utilize simpler carbon sources over toxic compounds when both are present in an environment and, therefore, the presence of simpler carbon sources may greatly reduce the efficiency of a microorganism towards toxic compounds. If a microorganism is prevented from utilizing simpler carbon sources, thereby making it totally dependent upon the toxic compounds, it should increase the specificity for and efficiency of degradation of the toxic compounds in the presence of other, simpler carbon sources. To test this hypothesis, the efficiency of naphthalene and salicylate degradation in the presence of glucose by a recombinant Pseudomonas putida strain mutated in glucose metabolism was determined and compared to the non-mutated strain. Results obtained indicate that the impairment of glucose metabolism leads to better degradation of naphthalene and salicylate in the presence of glucose.

Biodegradation, Environmental↗
PubMed2000

Broad substrate specificity of naphthalene- and biphenyl-utilizing bacteria.

Although aromatic compounds are most often present in the environment as components of complex mixtures, biodegradation studies commonly focus on the degradation of individual compounds. The present study was performed to investigate the range of aromatic substrates utilized by biphenyl- and naphthalene-degrading environmental isolates and to ascertain the effects of co-occurring substrates during the degradation of mono-aromatic compounds. Bacterial strains were isolated on the basis of their ability to utilize either biphenyl or naphthalene as a sole source of carbon. Growth and transformation assays were conducted on each isolate to determine the range of substrates degraded. One isolate, Pseudomonas putida BP18, was tested for the ability to biodegrade benzene, toluene, ethylbenzene and xylene isomers (BTEX) individually and as components of mixtures. Overall, the results indicate that organisms capable of growth on multi-ring aromatic compounds may be particularly versatile in terms of aromatic hydrocarbon biodegradation. Furthermore, growth and transformation assays performed with strain BP18 suggest that the biodegradation of BTEX and biphenyl by this strain is linked to a catabolic pathway with overlapping specificities. The broad substrate specificity of these environmental isolates has important implications for bioremediation efforts in the field.

Alcaligenes↗