Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.31 (beta-glucuronidase)
 7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The time-dependent metabolism of 2-nitrofluorene (2-NF) in vivo has been studied after ip administration to rats. After hydrolysis with beta-glucuronidase/arylsulfatase, five hydroxylated 2-nitrofluorenes were isolated by HPLC and identified by a combination of data from NMR, UV, and MS experiments. These metabolites were characterized as 6,9-dihydroxy-2-nitrofluorene (I), 9-hydroxy-2-nitrofluorene (II), 6-hydroxy-2-nitrofluorene (III), 7-hydroxy-2-nitrofluorene (IV), and 8-hydroxy-2-nitrofluorene (V). The highest amounts of metabolites were found after 24 h of injection, and although the major ones were still present after 48 h, only traces of them could be found beyond that time. A unique feature of the present study was our ability to establish the position of the different hydroxylations that occur in vivo by NMR techniques and, thus, to observe the regioselectivity of the metabolism of the 2-NF in vivo. Furthermore, two conjugated metabolites were identified by 1H-NMR and ESI-MS as 6-[(hydroxysulfonyl)oxy]-2-nitrofluorene (2-nitrofluorene 6-sulfate) (VI) and 7-[(hydroxysulfonyl)oxy]-2-nitrofluorene (2-nitrofluorene 7-sulfate) (VII).
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PMID:Regioselective hydroxylations of 2-nitrofluorene in vivo: a nuclear magnetic resonance study. 934 28

Biotransformation of the phytoestrogen [14C]genistein was investigated in male and female rats by application of narrow-bore radio-HPLC-MSn (LCQ, Finnigan) to determine intermediates in metabolism. Urine contained five metabolites, Gm1-Gm5, 24 h after dosing by gavage with [14C]genistein (4 mg kg(-1)). Structural analysis following ESI revealed molecular ions [M+H]+ of m/z 447, 449, 273, and 271 for metabolites Gm2, Gm3, Gm5 and genistein, respectively and an [M-H]- of m/z 349 for Gm4. Metabolite structure was deduced by evaluation of product ion spectra derived from unlabelled and [14C]-labelled ions and sensitivity to treatment with beta-glucuronidase. These studies indicated identity of metabolites with genistein glucuronide (Gm2), dihydrogenistein glucuronide (Gm3), genistein sulphate (Gm4) and dihydrogenistein (Gm5). Detection of the beta-glucuronidase resistant major metabolite Gm1 by ESI was poor and so was analysed by negative ion APCI; this revealed a deprotonated molecular ion of m/z 165 which had chromatographic and mass spectral properties consistent with authentic 4-hydroxyphenyl-2-propionic acid, a novel metabolite of genistein. In vitro metabolism studies with anaerobic caecal cultures derived from male and female rats revealed metabolism of genistein to Gm1 via Gm5 and an additional metabolite (Gm6) which was identified from product ion spectra as 6'-hydroxy-O-desmethylangolensin. Biotransformation of genistein by both isolated hepatocytes and precision-cut liver slices was limited to glucuronidation of parent compound. Commonality of genistein metabolites found in rats with those reported in man suggest similar pathways of biotransformation, primarily involving gut micro-flora.
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PMID:Biotransformation of genistein in the rat: elucidation of metabolite structure by product ion mass fragmentology. 1062 5

Ketobemidone and five of its phase I metabolites were identified in the urine of four patients post intravenous administration of Ketogan Novum. Furthermore, indications of the presence of the glucuronide conjugates of ketobemidone and norketobemidone is presented. Both hydrolyzed (beta-glucuronidase) and unhydrolyzed human urine was extracted on a mixed-mode slightly polar cation-exchange SPEC cartridge prior to analysis with LC-ESI-MS-MS. The phase I metabolites were identified by comparison of their daughter spectra with those of synthesized standards. The glucuronides were identified by their molecular mass and interpretation of the daughter spectra, as no standards were available for these compounds.
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PMID:Identification of phase I and phase II metabolites of ketobemidone in patient urine using liquid chromatography-electrospray tandem mass spectrometry. 1171 May 70

Lorazepam (LOR) is a 3-hydroxy-1,4-benzodiazepine that is chiral and undergoes enantiomerization at room temperature. In humans, about 75% of the administered dose of LOR is excreted in the urine as its 30-glucuronide. CE-MS with negative ESI was used to confirm the presence of LOR-30-glucuronide in urines that stemmed from a healthy individual who ingested 1 or 2 mg LOR, whereas free LOR could be detected in extracts prepared from enzymatically hydrolyzed urines. As the 30-glucuronidation reaction occurs at the chiral center of the molecule, two diastereoisomers can theoretically be formed, molecules that can no longer interconvert. The stereoselective formation of LOR glucuronides in humans and in vitro was investigated. MEKC analysis of extracts of the nonhydrolyzed urines suggested the presence of the two different LOR glucuronides in the urine. The formation of the same two diastereoisomers was also observed in vitro employing incubations of LOR with human liver microsomes in the presence of uridine 5'-diphospho-glucuronic acid as coenzyme. The absence of other coenzymes excluded the formation of phase I or other phase II metabolites of LOR. Both results revealed a stereoselectivity, one diastereoisomer being formed in a higher amount than the other. After enzymatic hydrolysis using beta-glucuronidase, these peaks could not be detected any more. Instead, LOR was monitored. Analysis of the extracts prepared from enzymatically hydrolyzed urines by MEKC in the presence of 2-hydroxypropyl-beta-CD revealed the enantiomerization process of LOR (observation of two peaks of equal magnitude connected with a plateau zone). The data presented provide for the first time the evidence of the stereoselectivity of the LOR glucuronidation in humans.
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PMID:Analysis of lorazepam and its 30-glucuronide in human urine by capillary electrophoresis: evidence for the formation of two distinct diastereoisomeric glucuronides. 1648 21

A liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) method has been developed for the analysis of buprenorphine (BUP) and nor-buprenorphine (NBUP) in biological fluids. Analytes are isolated from urine and blood, after addition of d4-buprenorphine (d4-BUP) as internal standard, by solid-phase extraction. Preparation of hair involves external decontamination, mechanical pulverization, overnight incubation in acidic medium, and neutralization prior to extraction. Enzymatic hydrolysis with beta-glucuronidase may be performed to distinguish between free and total BUP. Chromatographic separation is accomplished by gradient elution on a cyanopropyl 2.1 x 150 mm column. Positive ion ESI and MS analyses are carried out in an ion trap mass spectrometer. The use of this mass analyzer allows effective collisional experiments to be performed on ESI-generated MH+ species. Abundant product ions are produced, which can be monitored together with precursor ions without losing sensitivity. Thus, assay selectivity is definitely increased with respect to LC/ESI-MS/MS methods in which only precursor ions are monitored. The method has good linearity (calibration curves were linear in the range 0.1-10 ng/mL in urine and blood, in the range 10-160 pg/mg in hair) and limits of detection of 0.05 ng/mL for both BUP and NBUP in blood and urine samples, of 4 pg/mg for both analytes in hair. Both intra- and inter-assay precision and accuracy were satisfactory at three concentrations studied: relative standard deviations were <13.7% in urine, <17.3% in blood, <17.8% in hair; percent deviation of the mean from the true value was always <10.5% in urine and blood, <16.1% in hair. The method can be used to determine both analytes in the urine and hair of drug addicts on replacement therapy, and in post-mortem blood specimens when there is suspicion of drug-related death.
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PMID:Potentials of ion trap collisional spectrometry for liquid chromatography/electrospray ionization tandem mass spectrometry determination of buprenorphine and nor-buprenorphine in urine, blood and hair samples. 1655 Apr 95

The present study reports a novel method for the production and purification of analytical standards of glucuronide conjugates of bile acids, chenodeoxycholic (CDCA), lithocholic, (LCA) and hyodeoxycholic (HDCA) acids. CDCA-3G (CDCA-3-glucuronide) and -24G, LCA-3G and -24G, and HDCA-6G and -24G were enzymatically formed by using microsomes from human liver, purified by liquid chromatography, digested with recombinant beta-glucuronidase, and quantified by liquid chromatography/electrospray ionization coupled to mass spectrometry (LC-ESI/MS). The position of the glucuronosyl moiety on the bile acids was determined by analyzing the susceptibility to hydrolysis under elevated pH and temperature conditions of the standards. By using the purified analytical standards, a LC-ESI/MS/MS method was developed for the determination of these glucuronide conjugates in in vitro assays. The linearity of the assay ranged from 0.5 to 40 ng/mL for the six glucuronides, and the limit of quantification (LOQ) was 0.5 ng/mL. Intra- and interday precisions and accuracy values were all lower than 10.2%. Furthermore, processed sample stability analyses revealed that the six standards were stable at 4 degrees C for more than 24 h. This method was successfully used for the quantification of CDCA, LCA, and HDCA glucuronides formed by human liver or hepatoma HepG2 cells. In conclusion, such a method allows the purification of high-quality analytical standards of glucuronide derivatives and may easily be used for the quantification of other endo- and xenobiotics that are glucuronidated.
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PMID:Enzymatic production of bile Acid glucuronides used as analytical standards for liquid chromatography-mass spectrometry analyses. 1674 61

A comprehensive analytical method has been developed and validated for the simultaneous determination of seventeen glucocorticoid residues in eggs and milk. The mass spectrometer parameters, the composition of the mobile phase and the sample preparation method were firstly optimized to obtain maximum sensitivity. The samples were deconjugated with beta-glucuronidase/arylsulfatase enzyme and concentrated using an Oasis HLB solid-phase extraction cartridge, followed by cleanup with a dual Sep-pak silica and aminopropyl cartridge. The analytes were quantified by ultra-performance liquid chromatography (using a C18 column)/electrospray ionization tandem mass spectrometry (UPLC/ESI-MS/MS) operating in the negative ion mode. The assay for the 17 glucocorticoids was linear over the range of 1-200 microg/L for milk and egg samples with a high correlation coefficient (>0.99). The limits of quantification (LOQs) for the target analytes were 0.04-1.27 microg/kg for the egg samples and 0.03-0.73 microg/kg for the milk samples. The average extraction recoveries of the glucocorticoids from eggs and milk at two concentration levels (spiked at 0.40 and 2.00 microg/kg) were 65.6-118.7% and 61.5-119.6%, respectively, with relative standard deviations between 1.8-17.0% and 2.4-18.4%, respectively. Because of its high sensitivity, good precision and specificity, the method was found to be suitable for trace analysis of synthetic and natural glucocorticoids in complex biosamples such as eggs and milk.
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PMID:Simultaneous determination of seventeen glucocorticoids residues in milk and eggs by ultra-performance liquid chromatography/electrospray tandem mass spectrometry. 1683 49

The aquatic crustacean Daphnia magna is an important species for ecotoxicological study, and is often used as a test organism for environmental risk assessment. However, the mechanism of xenobiotic metabolism by this species has not been studied in detail. In the present study, pyrene was used as model substance to investigate the mechanism of xenobiotic metabolism in D. magna. The results of 24-h exposure experiments showed that D. magna could metabolize pyrene and biotransform it into water-soluble metabolites. On the other hand, the metabolism of pyrene was significantly inhibited by SKF-525A as the cytochrome P450 (CYP) inhibitor. These observations indicated that oxidation by CYP participated in the biotransformation of pyrene by D. magna. We also identified the pyrene metabolites formed by D. magna by HPLC with an electrospray ionization triple quadrupole mass spectrometry detector (LC/ESIMS/MS) and de-conjugation by sulfatase, beta-glucuronidase, and beta-glucosidase. One of the metabolites was ionized in ESI negative mode and formed a dominant mass of m/z 297 (MS) with the product ion of m/z 217 (MS2). Furthermore, this metabolite formed 1-hydroxypyrene on treatment with sulfatase. This metabolite was considered to be a sulfate conjugate of oxidized pyrene (1-hydroxypyrenesulfate). Furthermore, we quantified the deconjugated 1-hydroxypyrene formed by the above enzyme treatment. It showed that 52% of the total metabolized pyrene was biotransformed into 1-hydroxypyrene-sulfate, and more than 73% was biotransformed into oxidized pyrene conjugate. These results indicated that CYP and several conjugation enzymes participate in its biotransformation, and sulfation is important in D. magna for metabolism and elimination of xenobiotics.
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PMID:Metabolism of pyrene by aquatic crustacean, Daphnia magna. 1697 24

Plagiochin E, a macrocyclic bisbibenzyl isolated from liverwort Marchantia polymorpha, was found to have antifungal activity. To evaluate the pharmacokinetics of plagiochin E in rats, a sensitive and specific liquid chromatography/tandem mass spectrometric (LC-MS/MS) method was developed and validated for the quantitation of plagiochin E and its total conjugated metabolites in rat plasma. For detection, a Sciex API 4000 LC-MS/MS with a TurboIonSpray ionization (ESI) inlet in the negative ion-multiple reaction monitoring (MRM) mode was used. The plasma samples were pretreated by a simple liquid-liquid extraction with ethyl acetate. The concentration of plagiochin E parent form was determined directly and the concentration of plagiochin E conjugated metabolites was assayed in the form of plagiochin E after treatment with beta-glucuronidase/sulfatase. The statistical evaluation for this method reveals excellent linearity, accuracy and precision for the range of concentrations 0.5-1000.0 ng/mL. The method had a lower limit of quantification (LLOQ) of 0.5 ng/mL for plagiochin E in 50 microL of plasma. The method was successfully applied to the characterization of the pharmacokinetic profile of plagiochin E in rats after an oral and an intravenous administration.
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PMID:Liquid chromatography-tandem mass spectrometry assay for the quantitation of plagiochin E and its main metabolite plagiochin E glucuronides in rat plasma. 1842 Mar 69

Recent studies show that ethyl glucuronide (EtG) can be decomposed by bacteria; whilst so far no degradation of ethyl sulphate (EtS) has been observed. In the present study, in vitro experiments with bacterial colonies were performed. Bacteria (Escherichia coli, Klebsiella pneumoniae, Clostridium sordellii) were isolated from autopsy material (liver, heart blood, urine, ascites, pericardial fluid, pleural fluid) tested for beta-glucuronidase activity, and three bacterial strains were added to nutrient-deficient medium containing EtG and/or EtS and incubated at 36 +/- 1 degrees C. Samples were taken after various intervals up to 11 days, and EtG and EtS were determined by electrospray ionisation tandem mass spectrometry (LC-ESI-MS/MS). EtG was degraded by E. coli and C. sordellii--complete degradation occurred in the range of 3-4 days--and these bacteria exhibited beta-glucuronidase activity. EtS was not affected within 11 days of incubation.
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PMID:In vitro study of bacterial degradation of ethyl glucuronide and ethyl sulphate. 1857 90


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