Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Lorazepam and oxazepam in plasma and urine were measured by gas chromatography-mass spectrometry. Oxazepam was used as an internal standard in the assay of lorazepam and vice versa. After removal of interfering substances with n-hexane, the drugs were extracted with benzene and converted to N1,O3-bistrimethylsilyl derivatives. Glucuronide forms of the drugs were extracted after hydrolysis with beta-glucuronidase. A common fragment ion at m/e 429 was used to monitor the two drugs. The sensitivity was 2 ng/ml for both drugs, which was sufficient to determine plasma and urine concentrations after therapeutic doses to humans.
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PMID:Simplified determination of lorazepam and oxazepam in biological fluids by gas chromatography-mass spectrometry. 4 99

A simple rapid method for simultaneous ethosuximide and phenobarbital assay in brain tissue, serum and urine has been developed. Extraction of samples from brain tissue and serum were performed with dichloromethane at low pH in the presence of an excess of ammonium sulfate. Glucuronide conjugates in urine samples were hydrolyzed by enzymatic cleavage with beta-glucuronidase and then extracted with dichloromethane. The extracts were analyzed using a Spherisorb 5 ODS column and a mixture of acetonitrile, methanol and phosphate buffer (21:24:55, v/v) as eluent. No interference was encountered and the method is both precise and reproducible.
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PMID:Simultaneous measurement of ethosuximide and phenobarbital in brain tissue, serum and urine by HPLC. 273 17

The assay of UDPglucuronosyltransferase activity toward various substrates using UDP[U-14C]glucuronic acid is described. HPLC on a polar amino-cyano bonded phase column was used to separate radioactive glucuronides from unmetabolized UDP[U-14C]glucuronic acid and other labeled reaction products. Radioactivity was measured using flow-through scintillation counting. All the glucuronides analyzed, with one exception, chromatographed with the same retention time (9.0-9.6 min) under the conditions described. Glucuronide conjugates were identified by comparison with retention times of commercial glucuronide standards, using radioactive aglycones, or hydrolysis with beta-glucuronidase. The method provides a unified, sensitive (100-200 pmol of glucuronide product) and reproducible assay for a wide variety of UDPglucuronosyltransferase substrates, and could be extended to include many others.
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PMID:A general assay for UDPglucuronosyltransferase activity using polar amino-cyano stationary phase HPLC and UDP[U-14C]glucuronic acid. 310 43

All-trans retinoyl fluoride reacts with the 3,6-lactone of glucuronic acid in slightly alkaline solution to give the lactone of retinoyl beta-glucuronide, along with other retinoyl glucurono-lactones, in about 60% yield. Hydrolysis of the lactone with very dilute alkali gives the free acid, retinoyl beta-glucuronide, in about 80% yield. Pure all-trans retinoyl beta-glucuronide (overall yield: 20-25%) was obtained free from other isomeric and anomeric forms by reverse-phase high pressure liquid chromatography. Retinoyl beta-glucuronide was characterized by UV-visible, infrared, and 1H-NMR spectra, by elementary analysis, by mass spectra, and by its susceptibility to hydrolysis by bacterial beta-glucuronidase.
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PMID:Chemical synthesis of all-trans retinoyl beta-glucuronide. 390 6

Gas chromatography-negative-ion chemical ionization mass spectrometry (GC-NICI-MS) allowed the detection of extremely low plasma concentrations of 3-methoxy-4-hydroxyphenylethylene glycol (MHPG). Glucuronide and sulphate conjugates of MHPG were determined after enzymatic hydrolysis of plasma with beta-glucuronidase-arylsulphatase. A 1-ml plasma sample was extracted at the pH of the hydrolysis (pH 4.8) with ethyl acetate, and the dry extract was derivatized with pentafluoropropionic anhydride in ethyl acetate. After evaporation of the solvent, the residue was dissolved in benzene and an aliquot was analysed by GC-NICI-MS. A trideuterated analogue of MHPG was used as an internal standard. Negative-ion chemical ionization of the pentafluoropropionyl derivatives was carried out using ammonia. The ion-molecule adducts at m/e 766 and 785 (MHPG) and m/e 769 and 788 (internal standard) were formed from the pentafluoropropionyl derivatives with the ions of m/e 163 (CF3CF2COO-) and m/e 144 (loss of fluorine from m/e 163). The concentrations of the ions of m/e 163 and 144 play a major role in the sensitivity and precision of this technique, which allows the detection of free MHPG plasma concentrations as low as 100 pg/ml in routine analysis.
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PMID:Determination of low plasma concentrations of 3-methoxy-4-hydroxyphenylethylene glycol using gas chromatography-negative-ion chemical ionization mass spectrometry. 406 68

The glucuronidation of the AT1 nonpeptide angiotensin II receptor antagonist, SR 47436 (BMS 186295), was investigated in hepatic microsomes prepared from various species, i.e., Sprague-Dawley rat, Cynomolgus monkey and Caucasian humans. The drug was found to undergo N-glucuronidation on the tetrazole moiety as confirmed by its hydrolysis by beta-glucuronidase, its associated radioactivity when UDP-[U-14C]glucuronic acid was used as substrate and by different techniques such as high-performance liquid chromatography-mass spectrometry and nuclear magnetic resonance. Glucuronide formation was optimal at pH 5.0 along with a "0.2 mg of Brij 58 per mg of protein" ratio, regardless of the investigated species. Cynomolgus monkey microsomes glucuronidated SR 47436 (BMS 186295) to the greatest extent, with a relative catalytic efficiency 11.0- and 2.6-fold higher than that observed in rat and human, respectively. SR 47436 (BMS 186295) glucuronidation followed Michaelis-Menten kinetics. Bilirubin:UDP-glucuronosyltransferase isoform was not involved, inasmuch as bilirubin did not affect its glucuronidation, 7,7,7-triphenylheptanoic acid was a noncompetitive inhibitor and glucuronidation was only decreased 2-fold in Gunn rats. SR 47436 (BMS 186295) glucuronidation was enhanced markedly after treatment of rats with dexamethasone (Vmax/Km = 71.5 vs. 2.6 in untreated animals). Among the drugs used which undergo phenolic, carboxylic acid, alcohol or tertiary amine glucuronidation, only monodigitoxigenin-monodigitoxoside, flurbiprofen, naproxen, testosterone and estrone inhibited SR 47436 (BMS 186295) glucoronidation in a noncompetitive manner. These data suggest that SR 47436 (BMS 186295) was glucuronidated by a highly dexamethasone-inducible UDP-glucuronosyltransferase isoform(s), different from that involved in the glucuronidation of monodigitoxigenin-monodigitoxoside.
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PMID:In vitro N-glucuronidation of SB 47436 (BMS 186295), a new AT1 nonpeptide angiotensin II receptor antagonist, by rat, monkey and human hepatic microsomal fractions. 796 61

A method for the simultaneous quantitation of imipramine and six metabolites (2- and 10-hydroxyimipramine, 2- and 10-hydroxydesipramine, didesmethylimipramine and desipramine) in human plasma and urine has been developed. The method is based on a three-step liquid-liquid extraction followed by isocratic, reversed-phase high-performance liquid chromatography with ultraviolet absorbance detection (detection wavelength: 220 nm). The chromatographic eluent consisted of 30% acetonitrile and 70% aqueous sodium perchlorate solution pH 2.5. Glucuronide conjugates in urine were deconjugated with beta-glucuronidase/arylsulphatase prior to extraction.
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PMID:High-performance liquid chromatography of imipramine and six metabolites in human plasma and urine. 845 8

We studied thyroid hormone (TH) conjugation in fasted trout by incubating isolated hepatocytes with either [125I]T4 or [125I]T3, and by analyzing bile from trout injected with either [125I]T4 or [125I]T3. Glucuronide conjugates were identified by hydrolysis with beta-glucuronidase and sulfate conjugates by acid solvolysis with ethyl acetate/trifluoroacetic acid (1%). We used Sephadex LH-20 chromatography to concentrate the conjugate fractions from hepatocyte incubates prior to HPLC analysis. Glucuronide conjugates of T4 and T3 were produced in vitro and glucuronides of T4, T3, and 3,3'-T2 were found in vivo. Sulfation of T4 occurred in vitro and in vivo. T3 sulfation was not established in vitro, but sulfate conjugates of T3 and T2 were found in bile. Significant proportions of unconjugated T4 and T3 also occurred in the bile. We conclude that (i) as in other vertebrates, iodothyronines undergo hepatic glucuronidation and are excreted as such in the bile, (ii) T4 and T3 undergo sulfation, and in contrast to mammals, are excreted in significant amounts in the bile, (iii) 3,3'-T2, a prominent deiodination product of T3, is excreted as both glucuronide and sulfate conjugates, and (iv) the isolated hepatocyte system is appropriate for studying aspects of TH metabolism in trout.
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PMID:Identification of thyroid hormone conjugates produced by isolated hepatocytes and excreted in bile of rainbow trout, Oncorhynchus mykiss. 881 56

Goats were jugularly infused with the pneumotoxin 3-methylindole (3MI; 15 mg/kg, 0.5 microCi/kg) dissolved in cremophor-EL to characterize the urinary metabolites of 3MI in a ruminant specie. Urine was collected for 36 hr after the beginning of a 2-hr infusion period, and 3MI metabolites were purified using reversed-phase HPLC. Goats excreted 3MI as at least 11 distinct metabolites. Metabolites were characterized using a combination of UV spectroscopy, 1H- and 13C-NMR spectroscopy, and negative-ion FAB/MS. Two of the metabolites (E1 and E2), representing approximately 30% of the urinary radioactivity, were unambiguously identified as diastereomeric glucuronides of 3-hydroxy-3-methyloxindole [HMOI; 3-(beta-D-glucosiduronic acid)-3-methyloxindole]. Glucuronide conjugates were investigated using enzymatic and chemical hydrolysis. These ethereal glucuronides were unique in that they were not readily hydrolyzable with bovine beta-glucuronidase, although one of the diastereomers was hydrolyzed sparingly by beta-glucuronidase from Helix pomatia. Treatment of the glucuronides with 6 M HCI for a 2-hr period liberated unconjugated HMOI. Treatment of each diastereomer with dilute acid (pH 3) or dilute alkali (pH 10) was ineffective at hydrolyzing the conjugates. Goats form HMOI from 3MI and extensively glucuronidate the metabolite before excreting it, as opposed to mice that do not conjugate HMOI before excretion. These ethereal glucuronic acid conjugates seem to be unique in that they are essentially resistant to beta-glucuronidase-catalyzed hydrolysis.
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PMID:Identification of beta-glucuronidase-resistant diastereomeric glucuronides of 3-hydroxy-3-methyloxindole formed during 3-methylindole metabolism in goats. 882 99

Glucuronide derivatives of cytokinins have been synthesized for use as agents for the selection of plant cells transformed with a beta-glucuronidase (GUS) gene. In this selection system, the GUS gene functions as both a selectable, as well as a screenable gene. GUS liberates active cytokinin from inactive cytokinin glucuronides which then stimulates growth and regeneration of the transformed cells. The frequently used cytokinin N6-benzyladenine was conjugated to glucuronic acid at N-3 or at N-9 but only the former was a substrate for GUS. The glucuronide of isopentenyladenine was also made, by coupling at the N-3. This compound was readily hydrolysed by GUS.
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PMID:Synthesis of cytokinin glucuronides for the selection of transgenic plant cells. 937 16


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