Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Hydroxybenzoates”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 973 records · Page 54Linked to original sources
PubMed2004

Influence of diet and ration level on benzo[a]pyrene metabolism and excretion in rainbow trout (Oncorhynchus mykiss).

Juvenile rainbow trout (Oncorhynchus mykiss) were fasted or fed one of three isoenergetic diets varying in protein and lipid content at full satiation levels or half rations for up to 9 weeks. At 3, 6, and 9 weeks, fish in each treatment group were dosed intraperitoneally with 10 mg tritiated benzo[a]pyrene [3H]-B[a]P/kg (B[a]P) to examine the effects of diet composition and energy intake on xenobiotic biotransformation and excretion. The percent dose eliminated during the experiment did not differ among fish receiving the different diet compositions or rations (range 73% to 84%). However, it was significantly decreased (to 53%) in the group that was fasted for 9 weeks. Examination of fish fasted for 6 and 9 weeks showed a significant increase in the proportion of phase I metabolites and a concomitant decrease in the proportion of phase II metabolites found in bile compared with all other groups. Also, fish that were fasted for 9 weeks produced proportionately less 9,10-dihydroxy-benzo[a]pyrene-trans-9,10-diol, more 3-hydroxybenzo[a]pyrene and 9-hydroxybenzo[a]pyrene, and more glucuronic acid conjugates compared with all other groups. Thus, dietary protein and lipid concentration did not appear to affect either the rate of B[a]P metabolism or its excretion; however, prolonged fasting resulted in a shift in metabolite profiles and decreased excretion.

Animal Feed↗
PubMed1998

In vitro cytotoxicity of BTEX metabolites in HeLa cells.

Fuel leakage from underground storage tanks is a major source of groundwater contamination. Although the toxicity of regulated compounds such as benzene, toluene, ethylbenzene, and xylene (BTEX) are well recognized, the cytotoxicity of their metabolites has not been studied extensively. In this study, Hela cells, propagated at 37 degrees C in an atmosphere of 5% CO2-95% air, served as a target for evaluation of cytotoxicity of BTEX metabolites 3-methylcatechol, 4-methylcatechol, 4-hydroxybenzoic acid, and 4-hydroxy-3-methoxybenzoic acid. The cells were exposed to different concentrations of the metabolites, which subsequently showed inhibition of cell growth and produced dose-related decreases in cell viability and cell protein content. The BTEX metabolites affected the levels of the polyamines spermidine, spermine, and putrescine, which are known to be important in cell proliferation. The cytotoxic effects for these BTEX metabolites to Hela cells were 3-methylcatechol > 4-methylcatechol > 4-hydroxy-3-methoxybenzoic acid > 4-hydroxybenzoic acid.

Benzene Derivatives↗
PubMed2001

Degradation of biphenyl by Mycobacterium sp. strain PYR-1.

The metabolism of biphenyl by Mycobacterium sp. PYR-1 was investigated. The Mycobacterium sp. degraded >98% of the biphenyl added within 72 h. Analysis of ethyl acetate extracts of the culture medium by HPLC indicated that benzoic acid was the major metabolite. Other products were 4-hydroxybiphenyl, 4-hydroxybenzoic acid, and 5-oxo-5-phenylpentanoic acid. The metabolites were characterized by mass and 1H NMR spectrometry. Identification of benzoic acid and 5-oxo-5-phenylpentanoic acid indicates that biphenyl degradation by Mycobacterium sp. PYR-1 is generally similar to known pathways. A novel alternative metabolic pathway consisted of monooxygenation at C-4 of biphenyl to give 4-hydroxybiphenyl, with subsequent degradation via ring cleavage to 4-hydroxybenzoic acid.

Benzoic Acid↗
PubMed2003

Biodegradation of phenanthrene by Pseudomonas sp. strain PP2: novel metabolic pathway, role of biosurfactant and cell surface hydrophobicity in hydrocarbon assimilation.

Pseudomonas sp. strain PP2 isolated in our laboratory efficiently metabolizes phenanthrene at 0.3% concentration as the sole source of carbon and energy. The metabolic pathways for the degradation of phenanthrene, benzoate and p-hydroxybenzoate were elucidated by identifying metabolites, biotransformation studies, oxygen uptake by whole cells on probable metabolic intermediates, and monitoring enzyme activities in cell-free extracts. The results obtained suggest that phenanthrene degradation is initiated by double hydroxylation resulting in the formation of 3,4-dihydroxyphenanthrene. The diol was finally oxidized to 2-hydroxymuconic semialdehyde. Detection of 1-hydroxy-2-naphthoic acid, alpha-naphthol, 1,2-dihydroxy naphthalene, and salicylate in the spent medium by thin layer chromatography; the presence of 1,2-dihydroxynaphthalene dioxygenase, salicylaldehyde dehydrogenase and catechol-2,3-dioxygenase activity in the extract; O(2) uptake by cells on alpha-naphthol, 1,2-dihydroxynaphthalene, salicylaldehyde, salicylate and catechol; and no O(2) uptake on o-phthalate and 3,4-dihydroxybenzoate supports the novel route of metabolism of phenanthrene via 1-hydroxy-2-naphthoic acid --> [alpha-naphthol] --> 1,2-dihydroxy naphthalene --> salicylate --> catechol. The strain degrades benzoate via catechol and cis,cis-muconic acid, and p-hydroxybenzoate via 3,4-dihydroxybenzoate and 3-carboxy- cis,cis-muconic acid. Interestingly, the culture failed to grow on naphthalene. When grown on either hydrocarbon or dextrose, the culture showed good extracellular biosurfactant production. Growth-dependent changes in the cell surface hydrophobicity, and emulsification activity experiments suggest that: (1) production of biosurfactant was constitutive and growth-associated, (2) production was higher when cells were grown on phenanthrene as compared to dextrose and benzoate, (3) hydrocarbon-grown cells were more hydrophobic and showed higher affinity towards both aromatic and aliphatic hydrocarbons compared to dextrose-grown cells, and (4) mid-log-phase cells were significantly (2-fold) more hydrophobic than stationary phase cells. Based on these results, we hypothesize that growth-associated extracellular biosurfactant production and modulation of cell surface hydrophobicity plays an important role in hydrocarbon assimilation/uptake in Pseudomonas sp. strain PP2.

Aldehyde Oxidoreductases↗
PubMed2004

Fungal biotransformation of benzo[f]quinoline, benzo[h]quinoline, and phenanthridine.

Cultures of Umbelopsis ramanniana (=Mucor ramannianus) were grown in fluid Sabouraud medium for 3 days, dosed with 0.23 mM benzo[f]quinoline, benzo[h]quinoline, or phenanthridine (benzo[c]quinoline), and incubated for another 18 days. Cultures were extracted and metabolites (66-75% of the UV absorbance) were separated by high-performance liquid chromatography. They were identified by mass spectrometry and nuclear magnetic resonance spectroscopy. Benzo[f]quinoline was metabolized to benzo[f]quinoline trans-7,8-dihydrodiol, benzo[f]quinoline N-oxide, and 7-hydroxybenzo[f]quinoline, benzo[h]quinoline was metabolized to benzo[h]quinoline trans-5,6-dihydrodiol, benzo[h]quinoline trans-7,8-dihydrodiol, and 7-hydroxybenzo[h]quinoline, and phenanthridine was metabolized to phenanthridine N-oxide and phenanthridin-6(5H)-one. At least one of the metabolites produced from each compound was mutagenic and could not be considered detoxified.

Biotransformation↗
PubMed2006

Biodegradation of p-cresol by Bacillus sp. strain PHN 1.

A bacterium capable of utilizing p-cresol as sole source of carbon and energy was isolated from soil and identified as a Bacillus species. The organism also utilized phenol, o-cresol, m-cresol, 4-hydroxybenzoic acid, and gentisic acid as growth substrates. The organism degraded p-cresol to 4-hydroxybenzoic acid, which was further metabolized by a gentisate pathway, as evidenced by isolation and identification of metabolites and enzyme activities in the cell-free extract. Such a bacterial strain can be used for bioremediation of environments contaminated with phenolic compounds.

Bacillus↗
PubMed2002

Formation of benzoquinol moiety in cornoside by salidroside mono-oxygenase, a cytochrome P450 enzyme, from Abeliophyllum distichumcell suspension cultures.

A microsomal fraction prepared from Abeliophyllum distichumNakai (Oleaceae) cell suspension cultures oxidized salidroside, a glucoside of 4-hydroxyphenylethyl alcohol, to cornoside possessing a unique benzoquinol ring. The enzyme named salidroside mono-oxygenase required NADPH as the only cofactor, and molecular oxygen. The reaction was strongly inhibited by CO as well as several cytochrome P450 inhibitors, such as cytochrome c and miconazole, indicating the involvement of a cytochrome P450 enzyme. Salidroside mono-oxygenase accepted salidroside as the only substrate, but did not oxidize 4-hydroxyphenylethyl alcohol, the salidroside aglucone, and 4-hydroxybenzoic acid. The optimum pH of the reaction was 7.5, and apparent K(m) values for salidroside and NADPH were 44 micro M and 33 micro M, respectively. The benzoquinol ring formation mechanism is discussed in comparison to the mechanism for ipso substitution of 4-hydroxybenzoate by active oxygen species followed by elimination leading to hydroquinone.

Benzoquinones↗
PubMed1983

A microassay for UDP-glucose dehydrogenase.

An assay for UDP-glucuronic acid [J. Singh, L. R. Schwarz, and F. J. Wiebel, Biochem. J. 189, 369-372 (1980)] has been utilized for determining UDP-glucose dehydrogenase activity. The assay for UDP-glucuronic acid, a product of UDP-glucose dehydrogenase, is based on the fluorometric determination of D-glucuronosyl benzo(a)pyrene. This compound is formed from UDP-glucuronic acid and 3-hydroxybenzo(a)pyrene in a reaction catalyzed by the glycuronosyl transferase of guinea pig microsomes. Unreacted 3-hydroxybenzo(a)pyrene is removed by extraction with chloroform-methanol, and the amount of gluconosylbenzo(a)pyrene formed is determined fluorometrically. Because this assay for UDP-glucose dehydrogenase is about 500 times more sensitive than spectrophotometric assays, it can be used to measure the amount of enzyme extractable from milligram quantities of connective tissue. Some kinetic properties of UDP-glucose dehydrogenase extracted from rabbit tissue have been determined. No evidence of different forms of the enzyme in rabbit liver, cartilage, or corneal stroma was found.

Animals↗
PubMed1985

Dual-label high-performance liquid chromatographic assay for femtomole levels of benzo[a]pyrene metabolites.

A dual-label HPLC assay to measure femtomole quantities of ethyl acetate-extractable [3H]benzo[a]pyrene metabolites was developed. 14C-labeled metabolites of benzo[a]pyrene formed by rat liver 9000g supernatant were used as both internal standards and chromatographic markers. The percentage deviation between assays was determined to be between 11 and 13% for 9,10-dihydro-9,10-dihydroxybenzo[a]pyrene, 7,8-dihydro-7,8-dihydroxybenzo[a]pyrene, benzo[a]pyrene-3,6-quinone, benzo[a]pyrene-1,6-quinone, and 9-hydroxybenzo[a]pyrene, 22% for 4,5-dihydro-4,5-dihydroxybenzo[a]pyrene, and less than 5% for 3-hydroxybenzo[a]pyrene. The detection limit of this assay was between 3 and 10 fmol per metabolite. The application of this technique to the metabolism of [3H]benzo[a]pyrene by microsomes of hamster and human oral cavity tissue is described.

Animals↗
PubMed1987

Carboxypeptidase N: colorimetric assay using a new substrate.

A method has been developed for determining carboxypeptidase N (EC 3.4.17.3) activity by a hippuricase (EC 3.5.1.14)-assisted colorimetric assay. The method is based on the absorbance at 506 nm of a quinoneimine dye, produced by the action of carboxypeptidase N on the new substrates p-hydroxybenzoylglycine-L-Arg and p-hydroxybenzoylglycine-L-Lys. The enzyme acts on the substrates producing p-hydroxybenzoylglycine and L-Arg or L-Lys. The former is then hydrolyzed by hippuricase into p-hydroxybenzoic acid and Gly. Subsequently, oxidative coupling of p-hydroxybenzoic acid with 4-aminoantipyrine by sodium periodate forms a quinoneimine dye. The mean value of carboxypeptidase N activities in sera of 50 normal individuals was 30.8 (SD 5.9) nmol of p-hydroxybenzoylglycine released per milliliter of serum for the p-hydroxybenzoylglycine-L-Arg substrate and 137.8 (SD 28.1) for the p-hydroxybenzoylglycine-L-Lys substrate. The sensitivity of the assay is such that as little as 20 microliters of serum provides reliable and precise results (RSD% ranging from 1.8 to 4.9).

Adult↗
PubMed1989

Enzymatic method for measuring the absolute value of oxygen concentration.

An enzymatic method for measuring the absolute concentration of oxygen in aqueous solutions, using 4-hydroxybenzoate 3-monooxygenase and glucose oxidase, is described. The monooxygenase is used for quantitative oxidation of 4-hydroxybenzoate and NADPH with oxygen into 3,4-dihydroxybenzoate and NADP+; the amount of oxygen can be measured as the amount of NADPH decreased by the reaction. The monooxygenase reaction is performed in a syringe, a closed system. After the completion of the monooxygenase reaction, glucose oxidase is added to the assay solution to consume the oxygen from the atmosphere; this enables us to measure the NADPH concentration in the solution spectrophotometrically in an open system and to check the anaerobicity of closed systems. The oxygen concentrations at 25 degrees C of oxygen-saturated and air-saturated water were 1.10 and 0.23 mM, respectively. The value for argon-bubbled water was zero within the experimental error; this justifies the assay system. Thus, it is shown that a sample containing 8 microM-1.1 mM oxygen can be measured by this method.

Aspergillus↗
PubMed1984

Purification and immunochemical characterization of a low-pI form of UDP glucuronosyltransferase from mouse liver.

A liver UDP glucuronosyltransferase (GT) enzyme from either phenobarbital- or 3-methylcholanthrene-treated C57BL/6N mice was isolated by phenyl-Sepharose, DEAE-ion exchange, and UDP hexanolamine chromatographic steps. This enzyme had a broad substrate specificity and was mainly responsible for the microsomal capacity to glucuronidate testosterone, 1-naphthol, and morphine. This UDP glucuronosyltransferase ( GTM1 ) appeared to be at least 95% homogeneous and had a subunit molecular weight of 51,000 using sodium dodecyl sulfate-polyacrylamide gel and two-dimensional gel electrophoreses. Antibodies prepared against the purified protein developed a single immunoprecipitin line by double-diffusion analysis with purified antigen and with solubilized microsomes from both control and drug-induced C57BL/6N and DBA/2N mice. A precipitin line was also observed with microsomal proteins which isoelectrofocused at approximately pH 6.7, but not with those which isoelectrofocused at approximately pH 8.5. GTM1 was, therefore, designated at low-pI form. Immunopurified antibody preferentially inhibited and immunoprecipitated GT activities toward testosterone, 1-naphthol, and morphine. To a lesser extent, activities toward phenolphthalein, 3-hydroxybenzo[a]pyrene, and estrone were inhibited while activities toward 4-nitrophenol and 4-methylumbelliferone were not affected. All activities, however, were immunoadsorbed in the presence of protein A-Sepharose. This observation can be explained by the following results. Immunoprecipitates from labeled microsomes contained primarily a 51,000-Da protein. When the immune complexes were adsorbed with protein A-Sepharose, a 54,000-Da protein as well as the expected 51,000-Da GTM1 was detected. This 54,000-Da protein was associated with the glucuronidation of 3-hydroxybenzo[a]pyrene and 4-nitrophenol, and was designated GTM2 .

Animals↗
PubMed1984

The effects of anions on phosphoglycerate mutase.

Chloride (5-100 mM) can activate the phosphoglycerate mutase reaction (3-PG in equilibrium with 2-PG). I-, N0-3, or higher Cl- inhibit the mutase reaction while allowing mixing of isotope from [32P]3-PG into a large pool of 2,3-bisphosphoglycerate. p-Hydroxybenzoate inhibits without causing isotope dilution. A number of anions (p-hydroxybenzoate approximate equal to NO3- greater than Cl- greater than Tes greater than acetate) stimulate the P-glycolate activated 2,3-bisphosphoglycerate phosphatase reaction of this enzyme. The same anions inhibit competitively with P-glycolate. A kinetic analysis relates the anion effects to changes in rates of association and dissociation of substrates.

2,3-Diphosphoglycerate↗
PubMed1991

Dehalogenation of 4-chlorobenzoate by 4-chlorobenzoate dehalogenase from pseudomonas sp. CBS3: an ATP/coenzyme A dependent reaction.

Pseudomonas sp. CBS3 was grown with 4-chlorobenzoate as sole source of carbon and energy. Freshly prepared cell-free extracts converted 4-chlorobenzoate to 4-hydroxybenzoate. After storage for 16 hours at 25 degrees C only about 50% of the initial activity was left. Treatment at 55 degrees C for 10 minutes, dialysis or desalting of the extracts by gel filtration caused a total loss of the activity of the 4-chlorobenzoate dehalogenase. The activity could be restored by the addition of ATP, coenzyme A and Mg2+. If one of these cofactors was missing, no dehalogenating activity was detectable. The amount of 4-hydroxybenzoate formed was proportional to the amount of ATP available in the test system whereas CoA served as a real coenzyme. A novel ATP/coenzyme A dependent reaction mechanism for the dehalogenation of 4-chlorobenzoate by 4-chlorobenzoate dehalogenase from Pseudomonas sp. CBS3 is proposed.

Adenosine Triphosphate↗
PubMed1985

Separation of different UDP glucuronosyltransferase activities according to charge heterogeneity by chromatofocusing using mouse liver microsomes. Three major types of aglycones.

Hepatic UDP glucuronosyltransferase (EC 2.4.1.17) (GT) enzymes in control, phenobarbital- and 3-methylcholanthrene-induced microsomes from C57BL/6N mice have been fractionated according to charge heterogeneity on a chromatofocusing system using a pH 9.5 to 6 gradient. Transferase activities for eleven different substrates were determined on column fractions. Activities toward 3-hydroxybenzo[a]pyrene, phenolphthalein and estrone (type 1 substrates) were enhanced by both effector compounds and always eluted primarily at pH 8.5. In control and phenobarbital-induced microsomes, activities toward testosterone, 4-hydroxybiphenyl, morphine, naphthol and 9-hydroxybenzo[a]pyrene (type 2 substrates) eluted primarily at about pH 6.7. Activities toward p-nitrophenol, 4-methylumbelliferone and 2-hydroxybiphenyl (type 3 substrates) in control and phenobarbital-induced microsomes exhibited two peaks which eluted at pH 8.5 and 6.7. 3-Methylcholanthrene treatment increased almost exclusively activities which eluted at pH 8.5 for each of the three types of substrates. The pH value of elution corresponds to the approximate isoelectric point of the eluted protein. Immunoabsorption studies with an antibody preparation raised against a purified low pI form confirmed that a 51,000-dalton transferase form, GTM1, eluted primarily at pH 6.7 and that a 54,000-dalton form, GTM2, eluted at pH 8.5. A mathematical treatment of the ratios of activity after 3-methylcholanthrene treatment to that after phenobarbital treatment versus pH produced six patterns of activity. A minimum of two enzymes at the low pH region and one enzyme at the high pH region, all with broad-substrate specificity, could account for these patterns.

Animals↗
PubMed1980

Inhibition by norharman of metabolism of benzo[a]pyrene by the microsomal mixed function oxidase of rat liver.

The effect of norharman on the metabolism of ethyl acetate-soluble metabolic intermediates of benzo[a]pyrene (BP), 9,10-dihydro-9,10-dihydroxybenzo[a]pyrene (9,10-diol), 4,5-dihydro-4,5-dihydroxybenzo[a]pyrene (4,5-diol), 7,8-dihydro-7,8-dihydroxybenzo[a]pyrene (7,8-diol), benzo[a]pyrene diones, 3-hydroxybenzo[a]pyrene (3-OH-BP) and 9-hydroxybenzo[a]pyrene (9-OH-BP), were studied. These metabolic intermediates were converted by microsomal enzymes to other more polar ethyl acetate-soluble metabolites and then finally to the water-soluble metabolites. Norharman inhibited markedly the disappearance of each metabolite added as a substrate. With high-pressure liquid chromatographic (HPLC) separation it was revealed that formation of more polar metabolite was more efficiently inhibited by norharman than the formation of less polar metabolite. Formation of water-soluble metabolite was most efficiently inhibited by norharman. The mechanisms of the inhibitory effect of norharman on BP metabolism were studied by difference spectroscopy. On the addition of norharman, microsomes showed a type II difference spectrum, while on the addition of BP, they showed a type I difference spectrum. 3-OH-BP and 4,5-diol also gave a type I spectrum. Thus both BP and its metabolites bind to the active center of P-450, whereas norharman binds to the sixth ligand position of the iron ion of P-450. Kinetic studies showed that the Km-value of microsomes for BP was 6.25 microM in the presence and absence of norharman. This indicated that norharman inhibits the metabolism of BP non-competitively.

Alkaloids↗
PubMed1980

A benzo[alpha]pyrene-7,8-dihydrodiol-9,10-epoxide is the major metabolite involved in the binding of benzo[alpha]pyrene to DNA in isolated viable rat hepatocytes.

Benzo[alpha]pyrene is metabolised by isolated viable hepatocytes from both untreated and 3-methylcholanthrene pretreated rats to reactive metabolites which covalently bind to DNA. The DNA from the hepatocytes was isolated, purified and enzymically hydrolysed to deoxyribonucleosides. The hydrocarbon-deoxyribonucleoside products after initial separation, on small columns of Sephadex LH-20, from unhydrolysed DNA, oligonucleotides and free bases, were resolved by high pressure liquid chromatography (HPLC). The qualitative nature of the adducts found in both control and pretreated cells was virtually identical; however pretreatment with 3-methylcholanthrene resulted in a quantitatively higher level of binding. The major hydrocarbon-deoxyribonucleoside adduct, found in hepatocytes co-chromatographed with that obtained following reaction of the diol-epoxide, (+/-) 7 alpha,8 beta-dihydroxy-9 beta,10 beta-epoxy-7,8,9,10-tetrahydrobenzo[alpha]pyrene with DNA. Small amounts of other adducts were also present including a more polar product which co-chromatographed with the major hydrocarbon-deoxyribonucleoside adduct formed following microsomal activation of 9-hydroxybenzo[alpha]-pyrene and subsequent binding to DNA. In contrast to the results with hepatocytes, when microsomes were used to metabolically activate benzo[alpha]-pyrene, the major DNA bound-product co-chromatographed with the more polar adduct formed upon further metabolism of 9-hydroxybenzo[alpha]pyrene. These results illustrate that great caution must be exercised in the extrapolation of results obtained from short-term mutagenesis test systems, utilising microsomes, to in vivo carcinogenicity studies.

Animals↗
PubMed1985

The renal handling of terephthalic acid.

By use of the Sperber in vivo chicken preparation method (1948, Ann. R. Agric. Coll. Swed. 15, 317-349), infusion of radiolabeled terephthalic acid ([14C]TPA) into the renal portal circulation revealed a first-pass excretion of the unchanged compound into the urine. This model was utilized further to characterize the excretory transport of [14C]TPA and provide information on the structural specificity in the secretion of dicarboxylic acids. At an infusion rate of 0.4 nmol/min. 60% of the [14C]TPA which reached the kidney was directly excreted. An infusion rate of 3 or 6 mumol/min resulted in complete removal of [14C]TPA by the kidney. These results indicate that TPA is both actively secreted and actively reabsorbed when infused at 0.4 nmol/min and that active reabsorption is saturated with the infusion of TPA at higher concentrations. The secretory process was saturated with the infusion of TPA at 40 mumol/mn. The excretory transport of TPA was inhibited by the infusion of probenecid, salicylate, and m-hydroxybenzoic acid, indicating that these organic acids share the same organic anion excretory transport process. m-Hydroxybenzoic acid did not alter the simultaneously measured excretory transport of p-aminohippuric acid (PAH), suggesting that there are different systems involved in the secretion of TPA and PAH. The structural specificity for renal secretion of dicarboxylic acids was revealed by the use of o-phthalic acid and m-phthalic acid as possible inhibitors of TPA secretion. m-Phthalate, but not o-phthalate, inhibited TPA excretory transport, indicating that there is some specificity in the renal secretion of carboxy-substituted benzoic acids. TPA was actively accumulated by rat and human cadaver renal cortical slices.

Animals↗