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PubMedDate not supplied

Development of a microscale cell culture analog to probe naphthalene toxicity.

Prediction of human response to drugs or chemicals is difficult as a result of the complexity of living organisms. We describe an in vitro model that can realistically and inexpensively study the adsorption, distribution, metabolism, elimination, and potential toxicity (ADMET) of chemicals. A microscale cell culture analog (microCCA) is a physical replica of the physiologically based pharmacokinetics (PBPK) model. Such a microfabricated device consists of a fluidic network of channels to mimic the circulatory system and chambers containing cultured mammalian cells representing key functions of animal "organ" systems. This paper describes the application of a two-cell system, four-chamber microCCA ("lung"-"liver"-"other tissue"-"fat") device for proof-of-concept study using naphthalene as a model toxicant. Naphthalene is converted into reactive metabolites (i.e., 1,2-naphthalenediol and 1,2-naphthoquinone) in the "liver" compartment, which then circulate to the "lung" depleting glutathione (GSH) in lung cells. Such microfabricated in vitro devices are potential human surrogates for testing chemicals and pharmaceutics for toxicity and efficacy.

Animals↗
PubMed2004

Reduction of benzene and naphthalene mass transfer from crude oils by aging-induced interfacial films.

Semi-rigid films or skins form at the interface of crude oil and water as a result of the accumulation of asphaltene and resin fractions when the water-immiscible crude oil is contacted with water for a period of time or "aged". The time varying patterns of area-independent mass transfer coefficients of two compounds, benzene and naphthalene, for dissolution from crude oil and gasoline were determined. Aqueous concentrations of the compounds were measured in the eluent from flow-through reactors, where a nondispersed oil phase and constant oil-water interfacial area were maintained. For Brent Blend crude oil and for gasoline amended with asphaltenes and resins, a rapid decrease in both benzene and naphthalene mass transfer coefficients over the first few days of aging was observed. The mass transfer coefficients of the two target solutes were reduced by up to 80% over 35 d although the equilibrium partition coefficients were unchanged. Aging of gasoline, which has negligible amounts of asphaltene and resin, did not result in a change in the solute mass transfer coefficients. The study demonstrates that formation of crude oil-water interfacial films comprised of asphaltenes and resins contribute to time-dependent decreases in rates of release of environmentally relevant solutes from crude oils and may contribute to the persistence of such solutes at crude oil-contaminated sites. It is estimated that the interfacial film has an extremely low film mass transfer coefficient in the range of 10(-6) cm/min.

Benzene↗
PubMed1992

Theoretical IR spectra of ionized naphthalene.

We report the results of a theoretical study of the effect of ionization on the IR spectrum of naphthalene, using ab initio molecular orbital theory. For that purpose we determined the structures, band frequencies, and intensities of neutral and positively ionized naphthalene. The calculated frequencies and intensities allowed an assignment of the most important bands appearing in the newly reported experimental spectrum of the positive ion. Agreement with the experimental spectrum is satisfactory enough to take into consideration the unexpected and important result that ionization significantly affects the intensities of most vibrations. A possible consequence on the interpretation of the IR interstellar emission, generally supposed to originate from polycyclic aromatic hydrocarbons (PAHs), is briefly presented.

Chemical Phenomena↗
PubMed2002

Ligand-modulated stereo- and regioselective tandem addition reactions of rhenium-bound naphthalene.

A series of complexes of the form TpRe(CO)(L)(eta(2)-naphthalene) (Tp = hydridotris(pyrazolyl)borate) undergoes tandem electrophile/nucleophile addition reactions with a high degree of regiocontrol depending on the auxiliary ligand, L. When L = PMe(3), the reaction of the eta(2)-naphthalene complex with triflic acid followed by a silyl ketene acetal favors the 1,4-addition product, whereas when L = pyridine, N,N-dimethylaminopyridine, N-methylimidazole, or NH(3) the 1,2-addition product is favored. These reactions proceed with excellent stereocontrol: both electrophile (H(+), D(+)) and nucleophile (silyl ketene acetal) add anti to the face of metal coordination, and a single coordination diastereomer can be isolated for each reaction. One-electron oxidation of the Re complex affords the corresponding free dihydronaphthalene in good yield.

Crystallography, X-Ray↗
PubMed2004

Column preconcentration and spectrophotometric determination of ziram and zineb in commercial samples and foodstuffs using (1,2'-pyridylazo)-2-naphthol (PAN)-naphthalene as adsorbate.

A procedure has been developed for the determination of zinc(II) bis(dimethyldithiocarbamate) (ziram) and zinc(II) ethylenebis(dithiocarbamate) (zineb) after preconcentration on a column using naphthalene-(1,2'-pyridylazo)-2-naphthol (PAN) as adsorbent. Ziram and zineb are quantitatively retained on the column in the pH range of 9.0-12.5 and at a flow rate of 1-2 mL/min. The solid mass consisting of the Zn-PAN complex along with naphthalene is dissolved from the column with 5 mL of dimethylformamide (DMF). Absorbance of the complex was measured at 550 nm; Beer's law is obeyed over the concentration ranges of 2.0-22.0 microg of ziram and 5.0-19.8 microg of zineb in 10 mL of the final DMF solution. Ten replicate determinations on a sample solution containing 20 microg of ziram and 18 microg of zineb gave a mean absorbance of 0.33 with relative standard deviations of 0.80 and 0.70%, respectively. The interference of various ions has been studied. The method has been employed for the determination of ziram and zineb in commercial samples and in various foodstuffs, and the results were compared with the earlier reported methods.

Adsorption↗
PubMed1995

Design and synthesis of new naphthalenic derivatives as ligands for 2-[125I]iodomelatonin binding sites.

New melatonin-like agents were designed from the frameworks of 2,5-dimethoxyphenethylamine, an important structural moiety for the 5-HT receptor, and (2-methoxynaphthyl)-ethylamine. The compounds were synthesized by classical methods and evaluated in binding assays with chicken brain membranes using 2-[125I]iodomelatonin as the radioligand. Preliminary studies on the series of N-acyl-disubstituted phenethylamines showed the favorable role of the methoxy group in the ortho position of the side chain on the affinity for the receptor (Ki = 8 +/- 0.2 nM) for N-[2-(2-methoxy-5-bromophenyl)ethyl]propionamide (3o). This effect was confirmed in a series of the naphthalene derivatives, a bioisosteric moiety of the indole ring, and several potent ligands for melatonin binding sites were prepared such as N-[2-(2-methoxynaphthyl)ethyl]propionamide (4b) (Ki = 0.67 +/- 0.05 nM) and N-[2-(2,7-dimethoxynaphthyl)ethyl]cyclopropylformamide (Ki = 0.05 +/- 0.004 nM) (4k). Structure-activity relationships are discussed with regard to melatonin and bioisosteric naphthalenic compound 2. The Ki value for 4b was affected to a similar extent to that of melatonin by GTP-gamma-S or Mn2+ in competition experiments, suggesting an agonist profile for this compound.

Animals↗
PubMed1993

Synthesis and structure-activity relationships of naphthalene-substituted derivatives of the allylamine antimycotic terbinafine.

Derivatives of the allylamine antimycotic terbinafine (1) with varied substitution at the naphthalene ring system have been prepared, and their antifungal activity has been evaluated. In general, the potency is strongly dependent on the bulkiness of the substituent. Only hydrogen or in some cases fluorine are tolerated as substituents at positions 2-4 and 6-8 of the naphthalene moiety, whereas 5-substituents may be larger in size (F, Cl, Br, Me). Derivatives with fluorine at positions 3, 5, and 7 or chlorine at position 5 showed enhanced activity against yeasts relative to 1. This increase in sensitivity could be intensified by simultaneous introduction of two fluoro substituents at positions 5 and 7. Compound 7q demonstrated 8- to 16-fold improved potency against Aspergillus fumigatus, Candida albicans, and Candida parapsilosis.

Allylamine↗
PubMed1984

A substituent constant analysis of the interaction of substituted naphthalene monoimides with DNA.

In a continuing analysis of substituent effects in intercalator-DNA interactions, an unsubstituted naphthalene monoimide, with a 3-(dimethylamino)propyl group on the imide nitrogen has been prepared along with 3- and 4-nitro- and 3- and 4-amino-substituted derivatives. These derivatives allow an evaluation of the importance of the Hammett substituent constant and of the substituent position on the binding of naphthalene monoimides to DNA. Viscosity and spectrophotometric analyses indicate that all five compounds bind to DNA by intercalation. The 4-nitro compound gives a smaller viscosity increase and binds only approximately one-third as strongly as the 3-nitro derivative. It is postulated that this difference is due to the significant angle that the 4-nitro group makes with the intercalated monoimide ring system. The 3-NO2 group can assume a coplanar configuration with the monoimide ring system, allowing more favorable interactions with DNA base pairs, larger viscosity increases, and stronger binding to DNA. The binding constants of the 3-substituted monoimides are in the order 2 greater than 4 greater than 1 and, thus, do not follow a substituent constant pattern. The Tm values from thermal melting of DNA, on the other hand, are in the order 2 greater than 1 greater than 4, suggesting that the enthalpy contributions are significantly different for the binding of the three compounds to DNA. van't Hoff plots support this finding and indicate that both enthalpy and entropy contribute significantly to the binding free energy of 1 and 2 while the binding of 4 is primarily an enthalpic process. Plots of Tm and 65 degrees C log K values as a function of substituent constant for 1, 2, and 4 are linear. CPK model building studies suggest that 4 can form a hydrogen bond with the 5' diester oxygen of the sugar-phosphate backbone of DNA in an intercalation complex. This would lead to more favorable energetics of binding but a loss of mobility and/or available binding configurations with a resulting enthalpy-entropy compensation in the binding free energy of 4. This series of compounds dramatically illustrates the steric and hydrogen bonding complexity that can arise in attempts to design drugs to favorably interact with a DNA intercalation site as a potential bioreceptor.

Animals↗
PubMed2002

Naphthalene dicarboxaldehyde as an electrophilic fluorogenic moiety for affinity labeling: application to opioid receptor affinity labels with greatly improved fluorogenic properties.

To develop ligands with fluorogenic properties amenable for following the kinetics of cross-linking to receptors, a naphthalene dicarboxaldehyde moiety has been attached to an opiate pharmacophore 2 and evaluated in mu-opioid receptors. The fluorescence of the benzo[f]isoindole formed upon cross-linking of mu-opioid receptors by 2 permitted the time-course of covalent bonding to be followed. This demonstrated proof-of-concept suggests the usefulness of naphthalene dicarboxaldehyde-containing affinity labels as kinetic probes.

Affinity Labels↗
PubMed2004

Design and syntheses of 1,6-naphthalene derivatives as selective HCMV protease inhibitors.

Through high throughput screening of various libraries, substituted styryl naphthalene 6 was identified as an HCMV protease inhibitor. Optimization of various regions of the lead molecule using parallel synthesis resulted in 1,6-substituted naphthalenes 19d-i. These compounds displayed good potency and were selective over elastase, trypsin, and chymotrypsin. The optimization approach on lead compound 6 in three different regions of the molecule using parallel solution-phase synthesis and the corresponding SAR are discussed in detail.

2-Naphthylamine↗
PubMed2000

Photoreactivity of 2-pyridones with furan, benzene, and naphthalene. Inter- and intramolecular photocycloadditions.

Pyridones, well-known for their ability to photodimerize, have been found to undergo [4 + 4] photocycloaddition with furan and naphthalene but not with benzene. In some cases these reactions can be highly regio- and stereospecific. Intramolecular reaction with furan produces both cis and trans [4 + 4] products. The cycloaddition with naphthalene can occur both inter- and intramolecularly. The intermolecular reaction yields primarily the cis isomer, whereas the trans isomer is the major product from the intramolecular reaction. A mixture of 4-methoxy-2-pyridone and 2-methoxynaphthalene that could form up to eight regio- and stereoisomers forms largely one [4 + 4] product.

Benzene↗
PubMed2006

Formation of naphthalene, indene, and benzene from cyclopentadiene pyrolysis: a DFT study.

Four new reaction pathways for polycyclic aromatic hydrocarbon growth from cyclopentadiene pyrolysis are proposed and investigated using the B3LYP/6-31G(d,p) level of theory. These pathways allow for the production of indene, naphthalene, and benzene through intramolecular addition, C-H beta-scission, and C-C beta-scission reaction mechanisms, respectively. Results show that the intramolecular addition channel is favored at low temperatures, and the C-H beta-scission channel and the newly identified C-C beta-scission pathway become significant when the temperature increases. These results are in qualitative agreement with the experimental results previously obtained by this research group indicating that the main product at low temperature is indene, while benzene and naphthalene production dominate at the high-temperature end.

Algorithms↗
PubMed2001

Purification and characterization of a salicylate hydroxylase involved in 1-hydroxy-2-naphthoic acid hydroxylation from the naphthalene and phenanthrene-degrading bacterial strain Pseudomonas putida BS202-P1.

1-Hydroxy-2-naphthoate is formed as an intermediate in the bacterial degradation of phenanthrene. A monooxygenase which catalyzed the oxidation of 1-hydroxy-2-naphthoate to 1,2-dihydroxynaphthalene was purified from the phenanthrene- and naphthalene-degrading Pseudomonas putida strain BS202-P1. The purified protein had a molecular weight of 45 kDa and required NAD(P)H and FAD as cofactors. The purified enzyme also catalysed the oxidation of salicylate and various substituted salicylates. The comparison of the Km and Vmax values for 1-hydroxy-2-naphthoate and salicylate demonstrated a higher catalytic efficiency of the enzyme for salicylate as a substrate. A significant substrate-inhibition was detected with higher concentrations of 1-hydroxy-2-naphthoate. The aminoterminal amino acid sequence of the purified enzyme showed significant homologies to salicylate 1-monooxygenases from other Gram negative bacteria. It was therefore concluded that during the degradation of phenanthrene the conversion of 1-hydroxy-2-naphthoate to 1,2-dihydroxynaphthalene is catalysed by a salicylate 1-monooxygenase. Together with previous studies, this suggested that the enzymes of the naphthalene pathway are sufficient to catalyse also the mineralization of phenanthrene.

Amino Acid Sequence↗
PubMed2002

Biotransformation of naphthalene and diaryl ethers by green microalgae.

The role of green microalgae in the biotransformation of naphthalene (a polycyclic aromatic hydrocarbon) and diaryl ethers was investigated using axenic cultures of Chlorella vulgaris and two environmental isolates, Scenedesmus SI1 and Ankistrodesmus SI2. Biotransformation experiments with dense cell cultures showed that these three green algae transformed toxic xenobiotics to more polar metabolites. Chlorella vulgaris metabolized naphthalene to 1-naphthol (0.36-0.65%). Ankistrodesmus SI2 biotransformed dibenzofuran to six metabolites (total over 7%), three of which (possibly four) were identified as monohydroxylated dibenzofurans, the remaining two may be dihydroxylated derivatives. Scenedesmus SI1 biotransformed dibenzo-p-dioxin to three metabolites, one of which was tentatively identified as 2-hydroxydibenzo-p-dioxin (approximately 3.8%), the remainder may be dihydroxylated derivatives. This is the first time that the biotransformation of diaryl ethers by green microalgae has been investigated.

Biodegradation, Environmental↗
PubMed2004

Perinatal toxicity of domestic naphthalene exposure.

Naphthalene-containing mothballs can cause methemoglobinemia on inhalation. We describe a mother with hemolytic anemia and methemoglobinemia associated with elevated levels of naphthalene following exposure to mothballs. Her newborn infant had identical symptoms requiring mechanical ventilation and an exchange transfusion for resolution.

Adolescent↗
PubMed1994

Differential-pulse polarographic determination of zinc and manganese in various pharmaceutical and biological samples after adsorption of their morpholine-4-carbodithioates on microcrystalline naphthalene.

A highly selective, sensitive, rapid and economical differential-pulse polarographic method was developed for the simultaneous determination of trace amounts of zinc and manganese in various standard alloys and pharmaceutical, biological and environmental samples after adsorption of their morpholine-4-carbodithioates on microcrystalline naphthalene in the pH range 4.1-9.0 for manganese and 6.5-10.2 for zinc. After filtration, the metal complexes are shaken with 10 ml of 1 mol l-1 HCl and determined simultaneously using a differential-pulse polarograph. There is no need to remove naphthalene from the solution. Dissolved oxygen is removed by adding a few millilitres of 4% NaBH4 solution. The detection limits are 0.06 ppm for Mn and 0.1 ppm for Zn (signal-to-noise ratio = 2). Linearity is maintained in the concentration ranges 0.06-10 ppm for Mn and 0.1-12 ppm for Zn with a correlation factor of 0.9997 and relative standard deviations of 0.95 and 0.81%, respectively. The characterization of the electroactive process included an examination of the degree of reversibility. Various parameters such as the effect of pH, volume of aqueous phase and interference of a number of metal ions on the determination of manganese and zinc were studied in detail to optimize the conditions for their simultaneous determination (based on the large difference in their Ep values) in various biological, pharmaceutical and environmental samples.

Humans↗
PubMed2001

Rapid determination of sulfonated naphthalenes and their formaldehyde condensates in aqueous environmental samples using synchronous excitation fluorimetry.

Sulfonated naphthalenes and their formaldehyde condensates (SNFC) were determined in aqueous environmental samples by spectrofluorimetry. A clean-up step using n-hexane to extract possibly interfering nonpolar compounds such as naphthalene is the only preparatory procedure. Synchronous excitation mode with a gammalambda of 105 nm allows the determination of SNFC in environmental samples without additional clean-up or analyte enrichment. Interferences by humic acids and nitrate occurred only at concentrations higher than 1 mg C L(-1) and 10 mg NO3- L(-1), respectively. The limit of detection was 0.2 microg L(-1), the average recovery was 104% and the confidence interval (95% certainty) was 24%. The response factor for the quantitative determination of total SNFC, depending on the distribution of the different SNFC components, was validated for groundwater from two field sites using an HPLC-FD (fluorescence detection) method as a reference method.

Chromatography, High Pressure Liquid↗