Naphthalene Metabolites Research Articles

Catabolism of premercapturic acid pathway metabolites of naphthalene to naphthols and methylthio-containing metabolites in rats.

[14C]Naphthalene was given orally to rats with cannulated bile ducts and to germ-free rats. Bile and urine from the cannulated rats and urine from the germ-free rats contained no radioactive 1,2-dihydro-1-hydroxy-2-methylthionaphthalene and only trace amounts of radioactive naphthols or naphthol conjugates. Urine of control rats contained 4.6% of the 14C dose as naphthols and/or naphthol glucuronides. Appreciable quantities of 1- and 2-naphthol (7-20% of dose) and 1,2-dihydro-1-hydroxy-2-methylthionaphthalene (1-35% of dose) were in urine from rats dosed orally or intracecally with 1,2-dihydro-1-hydroxy-2-S-cysteinylnaphthalene and 1,2-dihydro-1-hydroxy-2-S-(N-acetyl)cysteinylnaphthalene. Apparently, in vivo, naphthols and methylthio-containing metabolites of naphthalene are formed during enterohepatic circulation of 1,2-dihydro-1-hydroxy-2-S-cysteinylnaphthalene and 1,2-dihydro-1-hydroxy-2-S-(N-acetyl)cysteinylnaphthalene in a process dependent upon intestinal microflora. A possible pathway for the formation of naphthols is aromatization of the precursor compounds by elimination of the appropriate substituent group from these metabolites. This discovery of the essential role of the intestinal microflora in the formation of naphthols from naphthalene indicates the existence of a novel pathway for hydroxylation of aromatic systems and challenges the current concept of the in vivo relevance of the in vitro production of naphthols from naphthalene 1,2-oxide.

Differences in naphthalene-induced toxicity in the mouse and rat

Following the intraperitoneal administration of naphthalene (200 mg/kg) to mice, the lung, in comparison with other organs, was selectively damaged. Histological examination of the lungs showed that it was the non-ciliated, bronchiolar epithelial cells (Clara cells) which were damaged. At higher doses (400 mg/kg and 600 mg/kg, i.p.), there was also damage to the cells in the proximal tubules of the kidney. In contrast to the effect in mice, doses of naphthalene as high as 1600 mg/kg (i.p.) caused no detectable pulmonary or renal damage in the rat. This difference in toxicity between the mouse and rat was reflected by the ability of naphthalene to more severely deplete the non-protein sulphydryls in the mouse lung and kidney than in those organs in the rat. In order to investigate the species difference in toxicity, the metabolism of naphthalene by lung and liver microsomes of the mouse and rat was studied. In all cases, naphthalene was metabolised to a covalently bound product(s) and to two major methanol-soluble products, which co-chromatographed with 1-naphthol and 1,2-dihydro-1,2-dihydroxynaphthalene. However, both the covalent binding and metabolism were approximately 10-fold greater in microsomes prepared from mouse lung compared with those from the rat. This observation may in part explain the difference in toxicity of naphthalene to the mouse and rat lung. As 1-naphthol is a major metabolite of naphthalene and previous work had suggested that most of the microsomal catalysed binding of naphthalene was due to further oxidation of 1-naphthol, the role of 1-naphthol in mediating the naphthalene-induced toxicity was investigated. In neither the mouse nor the rat did 1-naphthol cause a depletion of non-protein sulphydryl levels or tissue damage in the liver, lung or kidney. Thus the toxicity of naphthalene does not appear to be mediated via 1-naphthol.

Significance of active and passive depuration in the clearance of naphthalene from the tissues of Hemigrapsus nudus (Crustacea: Decapoda)

During August, 1977 adult male crabs (Hemigrapsus nudus) were exposed statically in seawater to 14C-naphthalene for 12 h, followed by up to 156 h of depuration. Uptake was rapid, and by 12 h the digestive gland had accumulated 105 times the water 14C, while other tissues had accumulated less than 15 times of this. Depuration was rapid at first, but slowed by 12 h post-exposure. After 156 h of depuration, the parent naphthalene that remained was primarily found in the digestive gland and muscle. However, the highest percentages of naphthalene metabolites were found in the gills, muscle, and hemolymph. Metabolites were retained to a greater degree than the parent compound. Because no significant difference in depuration rate was found between control individuals injected with 14C-naphthalene and those with their nephropores and anus blocked, it was concluded that the gills are the major route of naphthalene elimination. Thin layer chromatography (TLC) of extracts of depurated 14C-naphthalene indicated that <10% of the total naphthalene depurated was composed of metabolites. In-vitro mixed function oxygenase (MFO) activity was assayed on 15 000 g tissue homogenates, using diphenyloxazole as the terminal electron acceptor. The specific activity of the gills was 2 to 4 times that of the antennal glands, and no activity was detected in either muscle, digestive glands, or cardiac and pyloric stomachs. MFO activities were very low compared to fish or mammals. It was concluded that metabolism of naphthalene plays a minor role in the reduction of naphthalene levels, with the major role being played by simple diffusion of unmetabolized naphthalene down its concentration gradient. This occurs across the tissue with the largest body-to-water surface area, the gill.

Stereochemistry and evidence for an arene oxide-NIH shift pathway in the fungal metabolism of naphthalene

The mechanism of naphthalene oxidation by the filamentous fungus, Cunninghamella elegans is described. C. elegans oxidized naphthalene predominately to trans-1,2-dihydroxy-1,2-dihydronaphthalene. A trans configuration was assigned for the dihydrodiol by nuclear magnetic resonance (NMR) spectroscopy at 500 MHz which showed a large coupling constant (J 1,2) of 11.0 Hz. Comparison of the circular dichroism spectrum of the fungal trans-1,2-dihydroxy-1,2-dihydronaphthalene to that formed by mammalian enzyme systems indicated that the fungal dihydrodiol contained 76% (+)-(1 S,2 S)-dihydrodiol as the predominant enantiomer. Other naphthalene metabolites formed by C. elegans were identified as 1-naphthol, 2-naphthol and 4-hydroxy-1-tetralone. Incubation of C. elegans with naphthalene and 18O 2 indicated that the trans-1,2-dihydroxy-1,2-dihydronaphthalene contained one atom of molecular oxygen which indicated a monooxygenase catalyzed reaction while similar incubations with naphthalene and H 2 18O indicated that the oxygen atom in trans-1,2-dihydroxy-1,2-dihydronaphthalene was derived from water. Mass spectral analysis of the acid-catalyzed dehydration products of the dihydrodiol indicated that the naphthalene dihydrodiol forms via the addition of water at the C-2 position of naphthalene-1,2-oxide. Fungal metabolism of [1- 2H] naphthalene yielded 1-naphthol which retained 78% of the deuterium. NMR analysis of the deuterated 1-naphthol indicated an NIH shift mechanism in which deuterium migrated from the C-1 position to the C-2 position. The above results indicate that naphthalene-1,2-oxide is an intermediate in the fungal metabolism of naphthalene and that the fungal enzymes are highly stereo-selective in the formation of trans-1,2-dihydroxy-1,2-dihydronaphthalene.

Formation of reactive naphthalene metabolites by target vs non-target tissue microsomes: Methods for the separation of three glutathione adducts

Formation of reactive naphthalene metabolites by target vs non-target tissue microsomes: Methods for the separation of three glutathione adducts

Glucuronide and sulfate conjugation in the fungal metabolism of aromatic hydrocarbons

Cunninghamella elegans oxidized naphthalene to ethyl acetate-soluble and water-soluble metabolites. Experiments with [14C]-naphthalene indicated that 21% of the substrate was converted into metabolites. The ratio of organic-soluble metabolites to water-soluble metabolites was 76:24. The major ethyl acetate-soluble naphthalene metabolites were trans-1,2-dihydroxy-1,2-dihydro-naphthalene, 4-hydroxy-1-tetralone, and 1-naphthol. Enzymatic treatment of the aqueous phase with either arylsulfatase or beta-glucuronidase released metabolites of naphthalene that were extractable with ethyl acetate. In both cases, the major metabolite was 1-naphthol. The ratio of water-soluble sulfate conjugates to water-soluble glucuronide conjugates was 1:1. Direct analysis of the aqueous phase by high-pressure liquid and thin-layer chromatographic and mass spectrometric techniques indicated that 1-naphthyl sulfate and 1-naphthyl glucuronic acid were major water-soluble metabolites formed from the fungal metabolism of naphthalene. C. elegans oxidized biphenyl primarily to 4-hydroxy biphenyl. Deconjugation experiments with biphenyl water-soluble metabolites indicated that the glucuronide and sulfate ester of 4-hydroxy biphenyl were metabolites. The data demonstrate that sulfation and glucuronidation are major pathways in the metabolism of aromatic hydrocarbons by fungi.

Aromatic hydrocarbon metabolites in fish: authomated extraction and high-performance liquid chromatographic separation into conjugate and non-conjugate fractions

An automated extractor—concentrator was used to extract metabolites of naphthalene, 2,6-dimethylnaphthalene, and benzo[ a]pyrene from serum, bile and liver homogenate of rainbow trout ( Samlo gairdneri). The extracts were analyzed by reversed-phase high-performance liquid chromatography (HPLC) with fluorescence detection. Recoveries of naphthalene and 2,6-dimethylnaphthalene metabolites from all matrices were generally greater than 90%; however, the recoveries of benzo[ a]pyrene metabolites from serum ranged from 37–99%. In addition, conjugated metabolites of polycyclic aromatic hydrocarbons (PAHs) were separated from non-conjugated metabolites and parent PAHs by using two diol columns with normal-phase HPLC. The extraction and separation techniques were also applied to isolated metabolites in samples from fish fed 2,6-dimethylnaphthalene.

Formation of reactive metabolites of 14C-naphthalene in isolated rat hepatocytes and the effect of decreased glucuronidation and sulfation.

Naphthalene is metabolized in the liver to its epoxide which either may be converted enzymatically to the glutathione conjugate or to the naphthalene dihydrodiol leading to quinones, or may rearrange non-enzymatically to the corresponding phenol (Jerina et al., 1970). Reactive metabolites are formed during biotransformation of naphthalene which bind irreversibly to proteins. Using microsomal fractions it has been shown that covalent binding of this aromatic hydrocarbon is mainly mediated via generation of naphthol and not by the primary epoxide (Hesse and Mezger, 1979). To examine whether secondary metabolism might also be important for the formation of reactive metabolites under conditions which more closely resemble those in vivo, we studied metabolism and binding of 14C-naphthalene in isolated rat hepatocytes. This system has been shown to be very suitable for toxicological studies as isolated hepatocytes exhibit neither the limitations of drug metabolism of subcellular fractions nor the complexity of the intact animal (Schwarz and Greim, 1981). Moreover, the system is easy to handle and allows selective modulation of drug metabolism. In the following, we describe the effect of decreased glucuronidation and sulfation on the steady state level of reactive metabolites of naphthalene.

Uptake and accumulation of naphthalene by the oyster Ostrea edulis, in a flow-through system

A flow-through system was used to follow naphthalene and naphthalene metabolite accumulation in the seawater and in the tissue of the oyster Ostrea edulis. After 72 h, 82.5% of the naphthalene carbon was recovered from the system. Glucose was added to seawater to stimulate the pathways of glucose metabolism in the oysters. Streptomycin (100 ppm) reduced microbial oxidation of naphthalene and glucose, and reduced bacterial growth. However, even in the presence of streptomycin, microbial oxidation of naphthalene was considerable. The main oxidation product recovered from seawater was 14CO2. Radioactivity was also associated with compounds which separated by TLC with 2- and 1- naphthol. The pattern of naphthalene uptake and accumulation in oyster tissues was relatively constant after only a few hours of exposure to naphthalene. The potential of tissues to accumulate naphthalene was shown to be a function of multiple variables such as nutritional state, lipid concentration, length of exposure to naphthalene, and the external naphthalene concentration. Carbon-14-labeled metabolites derived from 14C-naphthalene were consistently recovered from digests of the oyster tissues. Non-CO2 alkaline-soluble substances were the primary metabolites. Hexane-extractable substances, which separated by TLC with known standards of 2- and 1- naphthol, were consistently recovered from seawater and tissue digests. It was not possible to conclude that these metabolites were a result of naphthalene metabolism by oyster enzyme systems.

The disposition of aromatic hydrocarbons in adult spot shrimp (Pandalus platyceros) and the formation of metabolites of naphthalene in adult and larval spot shrimp

1. Adult spot shrimp (Pandalus platyceros) exposed to 110 p.p.b. (microgram/ml) of the water-soluble fraction of Prudhoe Bay crude oil for one week accumulated a variety of low-molecular weight aromatic hydrocarbons (primarily C1-C5 substituted derivatives) in thoracic and abdominal tissues. 2. Adult and larval spot shrimp were exposed to 3H- and 14C- labelled naphthalene (a component of the water-soluble fraction) in seawater to delineate the types of metabolites formed. Both adults and larvae converted naphthalene to conjugated and non-conjugated structures such as the glucuronide, sulphate, dihydrodiol and phenolic derivatives. The presence of a quinone was also indicated.

The configuration of the 1,2-dihydroxy-1,2-dihydronaphthalene formed in the bacterial metabolism of naphthalene.

Both whole cells and cell-free extracts of Pseudomonas sp. (NCIB 9816) are shown to metabolise the cis-isomer of 1,2-dihydroxy-1,2-dihydronaphthalene at a much greater rate than the corresponding trans-isomeer, although the latter is eventually converted by cell-extracts to cis-o-hydroxybenzalpyruvic acid, an authenticated metabolite of naphthalene. Radioactivity trapping experiments with [14C]naphthalene, however, exclude the possibility that the trans-isomer is a metabolite of naphthalene as has been reported in the same organism.

The absolute configurations of the metabolites of naphthalene and phenanthrene in mammalian systems.

The absolute configurations of the metabolites of naphthalene and phenanthrene in mammalian systems.

The metabolism of naphthalene and its toxic effect on the eye

1. Naphthalene (1g./kg.) was fed daily by stomach tube to rabbits. 2. In more than half of the rabbits opacities in the lens and degeneration of the retina were visible in vivo. 3. Dissection of eye tissues revealed some or all of the following changes: a browning of the lens and eye humours, blue fluorescence of the eye humours and crystals in the retina and vitreous body. 4. The ascorbic acid concentration of the eye humours was decreased. 5. Some metabolites of naphthalene [1,2-dihydro-1,2-dihydroxynaphthalene, 2-hydroxy-1-naphthyl sulphate and (1,2-dihydro-2-hydroxy-1-naphthyl glucosid)uronic acid] are converted enzymically by the tissues of the eye into 1,2-dihydroxynaphthalene. 6. Changes in the eye are consistent with 1,2-dihydroxynaphthalene's being the primary toxic agent. The properties and reactions of this substance are described. 7. 1,2-Dihydroxynaphthalene is readily autoxidizable in neutral solution to form the yellow 1,2-naphthaquinone and hydrogen peroxide. This oxidation is reversed by ascorbate. 8. Ascorbate is oxidized catalytically by 1,2-naphthaquinone. This may account for the disappearance of ascorbate from the aqueous and vitreous humours of the eye after naphthalene feeding. It may also account for the appearance of crystals of calcium oxalate in the eye. 9. The brown colour of the lens of the naphthalene-fed rabbit is due to presence of naphthaquinone-protein compounds.

Metabolism of polycyclic compounds. 18. The secretion of metabolites of naphthalene, 1:2-dihydronaphthalene and 1:2-epoxy-1:2:3:4-tetrahydronaphthalene in rat bile

Metabolism of polycyclic compounds. 18. The secretion of metabolites of naphthalene, 1:2-dihydronaphthalene and 1:2-epoxy-1:2:3:4-tetrahydronaphthalene in rat bile

BIOCHEMICAL AND GENETIC ASPECTS OF PRIMAQUINE-SENSITIVE HEMOLYTIC ANEMIA

Excerpt Acute hemolysis, which may destroy half the red cells within a few days, occurs in approximately 10% of otherwise healthy American Negroes, very rarely in Caucasians,1, 2, 3when 30 mg. prim...

Metabolism of polycyclic compounds. X. Estimation of metabolites of naphthalene by paper chromatography.

Metabolism of polycyclic compounds. X. Estimation of metabolites of naphthalene by paper chromatography.

Metabolism of polycylic compounds. 8. Acid-labile precursors of naphthalene produced as metabolites of naphthalene.

Metabolism of polycylic compounds. 8. Acid-labile precursors of naphthalene produced as metabolites of naphthalene.

ACUTE HEMOLYTIC ANEMIA DUE TO INGESTION OF NAPHTHALENE MOTH BALLS

Naphthalene moth balls are potent hemolytic agents, capable of producing an acute, severe and perhaps fatal anemia. Moth ball poisoning should be suspected in children manifesting evidence of sudden hemolytic anemia, and an attempt should be made to demonstrate naphthalene or its derivatives in the urine. Care should be taken to prevent moth balls from being reached by infants and children. α- and β-naphthol and α- and β-naphthoquinone were found in the urine of a child suffering from severe hemolytic anemia due to ingestion of naphthalene moth balls. The hemolytic properties of naphthalene, of the naphthols and naphthoquinones were examined in vitro and in vivo (rabbits). Naphthalene itself was found to be nonhemolytic in vitro or in vivo. The hemolytic power of the naphthalene metabolites in vitro decreased in the following order: α-naphthol, β-naphthol, α-naphthoquinone, β-naphthoquinone. Hemolysis due to α-naphthol was observed in vivo (rabbits). However, its hemolytic action was significantly weaker than in vitro. β-naphthol and the naphthoquinones showed no hemolytic activity in vivo (rabbits). Plasma, cholesterol and lecithin did not inhibit the hemolytic activity of the naphthalene metabolites in vitro. Formation of methemoglobin was not observed.

642. Ultra-violet absorption spectra of some metabolites of naphthalene, anthracene, and phenanthrene

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