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)

Steroid acid esters, synthesized by modifying the 17-ketol side chain of prednisolone, were tested for their in vitro ability to stabilize heavy mitochondrial lysosomes prepared from rat liver. Membrane stabilization was determined by assessing capability of steroids to decrease extrusion of the marker enzymes (acid phosphatase, beta-glucuronidase and aryl sulfatase) from lysosomes incubated in hypo-osmotic sucrose-Tris acetate buffer. Results indicated that prednisolone (1) significantly inhibited the lysosomal release of acid phosphatase as did the new anti-inflammatory steroid, methyl 20-dihydroprednisolonate. Methyl prednisolonate exhibited weak membrane stabilization capacities and 20-dihydroprednisolonic acid, a metabolic product of methyl 20-dihydroprednisolonate, showed virtually no membrane stabilization.
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PMID:Stabilization of rat liver lysosomes by new anti-inflammatory steroids in vitro. 689 65

Iduronate sulfatase was purified from human liver for an investigation of the degradative pathway of dermatan sulfate. An overall 80-fold purification was achieved and, more importantly, the preparation was free of alpha-L-iduronidase, beta-glucuronidase, N-acetylgalactosamine 4-sulfate sulfatase (arylsulfatase B) and highly enriched in beta-N-acetylhexosaminidase. The liver enzyme appeared to be composed of several molecular species. The enzyme activity was optimal at pH 4.0 and its Km was 10--20 microM with sulfoiduronyl sulfoanhydromannitol. Chloride was inhibitory at high concentration and among divalent metal ions, only copper was inhibitory. Nitrocatechol sulfate was not a substrate, but did show competitive inhibition. Its Ki for iduronate sulfatase was similar to its Km for arylsulfatase, suggesting a similarity in the substrate binding sites of iduronate sulfatase and arylsulfatases.
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PMID:Purification and some properties of human liver iduronate sulfatase. 695 Sep 34

The plasma pharmacokinetics of the antineoplastic anthracycline antibiotic aclacinomycin A (Acm) and its metabolites were studied in 12 patients treated with 60-120 mg/m2 during a phase I clinical trial. Total plasma drug fluorescence initially declined very rapidly, but from 2 to 24 h after injection, fluorescence rose progressively to intensities greater than those measured 1 min after Acm injection. Plasma total drug fluorescence slowly declined from 24 to 72 hours after Acm administration. These events reflected the rapid disappearance of Acm and the subsequent appearance of two highly fluorescent metabolites. One metabolite co-chromatographed with and had a fluorescence spectrum identical to known metabolite F1 (bisanhydroaklavinone). The other metabolite did not co-chromatograph with any previously described Acm metabolite. This metabolite had a fluorescence spectrum unlike any previously described Acm metabolite and was not altered by treatment for 60 min with 0.2 N HCl at 100 degrees C or by treatment for 24 h at 37 degrees C with bacterial beta-glucuronidase or limpet aryl sulfatase.
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PMID:Plasma kinetics of aclacinomycin A and its major metabolites in man. 695 15

An automated HPLC method is described for the simultaneous determination of propranolol, 4-hydroxypropranolol, and N-desisopropylpropranolol in plasma and urine before and after beta-glucuronidase/aryl sulfatase treatment. It involves extraction with ether at pH 10 in the presence of ascorbic acid, added to prevent oxidation of 4-hydroxypropranolol. The compounds are then back extracted into dilute acid and assayed on an HPLC using a fluorescence detector. Three HPLC columns have been used (a phenyl, an octyl, and an octadecyl column). The last column was found to be most reproducible with minimal intercolumn variation. The solvent system includes a combination of acetonitrile, methanol, and phosphoric acid. Concentrations as low as 0.2, 1.0, and 0.2 ng/ml of propranolol, 4-hydroxypropranolol, and N-desisopropylpropranolol, respectively, can be measured using 1 ml of plasma.
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PMID:An automated HPLC method for the assay of propranolol and its basic metabolites in plasma and urine. 707 80

We have developed a rapid, sensitive and precise high-performance liquid chromatographic method using fluorescence detection for the simultaneous determination of thiabendazole and unconjugated 5-hydroxythiabendazole in serum. Sample pretreatment consists only of protein precipitation with acetonitrile containing the internal standard, 2-methylindole. Detection limits were found to be 0.1 microgram/ml serum for thiabendazole and 0.4 microgram/ml serum for 5-hydroxythiabendazole. Between-day analytical precision coefficients of variation for serum-based controls were 7% and 11% for thiabendazole levels of 1 and 5 micrograms/ml, respectively; and 43% and 8% for 5-hydroxythiabendazole levels of 6 and 60 micrograms/ml, respectively. We also devised a microenzymatic method for the conversion of the glucuronide and sulfate esters of 5-hydroxythiabendazole using beta-glucuronidase [EC 3.2.1.31] and sulfatase [EC 3.1.6.1]. Thus, quantitation of the separate metabolites was possible. We also utilized a special adaptation of the chromatographic procedure for the determination of the 5-hydroxythiabendazole metabolites in the sera of uremic patients, which can contain large amounts of interfering fluorescent substances. The method should be particularly useful for monitoring thiabendazole therapy in patients unable to eliminate the potentially toxic metabolites.
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PMID:Determination of thiabendazole and 5-hydroxythiabendazole in human serum by fluorescence-detected high-performance liquid chromatography. 710 70

A fluorescence high-performance liquid chromatographic method is described for the determination of 17-oxosteroids in biological fluids. 17-Oxosteroids in urine samples are extracted with dichloromethane after enzymatic hydrolysis (beta-glucuronidase-sulfatase), and dehydroepiandrosterone sulfate in serum samples is solvolysed with sulfuric acid in ethyl acetate. 17-Oxosteroids are labeled with dansyl hydrazine in trichloroacetic acid-benzene solution, and then chromatographed on the microparticulate silica gel column using dichloromethane-ethanol-water (400 : 1 : 2) as the mobile phase. The eluate is monitored by a fluorophotometer at 365 nm (excitation) and 505 nm (emission). Linearities of the fluorescence intensities (peak heights) with the amounts of various 17-oxosteroids were obtained between 60 and 1000 pg. The assay proved satisfactory with respect to sensitivity, precision and accuracy. The results obtained by a radioimmunoassay and this method were in good agreement (r = 0.964, n = 81) for serum dehydroepiandrosterone sulfate. This method is also use for the simultaneous determination of individual 17-oxosteroids in serum and urine.
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PMID:Determination of 17-oxosteroids in serum and urine by fluorescence high-performance liquid chromatography using dansyl hydrazine as a pre-labeling reagent. 732 Jan 36

A new method has been developed for measuring the total covalent binding of metabolically activated compounds to cellular macromolecules. This method employs equilibrium dialysis, in the presence of the detergent sodium dodecyl sulfate (SDS), to remove unbound radiolabeled compound and its metabolites from cellular macromolecules. [14C] Bromobenzene (80 microM), [14C]aflatoxin B1 (5 microM) or 3-[14C]methylcholanthrene (100 microM) was incubated (37 degrees C) with primary hepatocytes or liver microsomes isolated from Fischer-344 rats. The covalent binding of 14C-radiolabel to hepatic or microsomal macromolecules was measured by SDS-equilibrium dialysis and compared with that measured by exhaustive extraction. After 1 h of incubation with hepatocytes or microsomes, 2--7 times more covalent binding was detected by SDS-equilibrium dialysis, than by exhaustive extraction. The radioactivity associated with these hepatic or microsomal macromolecules migrated to discrete positions on SDS-polyacrylamide disc gels. The non-dialysable radioactivity from incubations with [14C] bromobenzene could not be extracted with diethyl ether even after treatment of the dialysin with beta-glucuronidase-sulfatase or dilute acid. This was taken to indicate that the radioactivity in the dialysin did not include free bromobenzene or its metabolites, a conclusion supported by thin-layer chromatography analysis of the dialysin. The lower amount of covalent binding detected by exhaustive extraction may be related to the inability of trichloroacetic acid to quantitatively precipitate small molecular weight macromolecules. SDS-equilibrium dialysis is an easy, rapid and non-destructive technique for measuring covalent binding. The macromolecular integrity of the sample is maintained and allows further studies concerning the specificity of the covalent interactions.
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PMID:A new method for measuring covalent binding of chemicals to cellular macromolecules. 742 16

Healthy subjects were administered single oral doses of 800 mg or 400 mg 3-[2-(benzoxazol-2-yl)ethyl]-5-ethyl-6-methylpyridin-2(1H)-o ne (L-696,229), a nonnucleoside inhibitor of the human immunodeficiency virus-type 1 (HIV-1) reverse transcriptase (RT). Plasma or urine samples were collected over a period of 48 hr. Pooled plasma (0.5-6 hr) and urine (0-24 hr) samples were analyzed by HPLC-UV and HIV-1 RT inhibition assay using poly rC.dG as a template primer. The parent compound and several common metabolites were detected in both samples. The metabolic profiles were also similar to those obtained from a rat liver slice incubation with [3H]L-696,229. The in vitro metabolites were identified by NMR and MS as 5 alpha-hydroxyethyl- (major), 5,6-dihydrodiol-, 6'-hydroxy-, 6-hydroxymethyl-, and 5-vinyl analogs, and a benzoxazole ring hydrolysis product. Most of the significant metabolites in human plasma and urine were found to be identical to the in vitro metabolites, as established by HPLC-UV and MS. Hydrolysis of the plasma and urine with beta-glucuronidase/sulfatase indicated the presence of significant amounts of conjugates of the parent compound and 5 alpha-hydroxyethyl metabolite. Most of the other primary metabolites were also present in conjugated forms, albeit in small quantities. In addition, two secondary metabolites were isolated and identified from the hydrolyzed urine as 5-acetyl-6'-hydroxy- and 5 alpha-hydroxyethyl-6-hydroxymethyl- analogs.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Metabolism of 3-[2-(benzoxazol-2-yl)ethyl]-5-ethyl-6-methylpyridin-2 (1H)-one (L-696,229), an HIV-1 reverse transcriptase inhibitor, by rat liver slices and in humans. 751 52

We studied the bioavailability and the plasma transport of flavonols in rats fed quercetin or rutin diets. Wistar rats were fed one of the following purified diets for 10 d: control; 16.4 or 8.2 mmol rutin/kg diet; or 16.4, 8.2 or 4.1 mmol quercetin/kg diet. Flavonol concentrations were determined in plasma, ileal and cecal contents, and feces. In rats fed diets containing 16.4 mmol quercetin or rutin/kg, the concentration of circulating flavonols was approximately 115 mumol/L. Quercetin or rutin administration resulted in similar concentrations of quercetin in cecal contents. By HPLC analysis and beta-glucuronidase/sulfatase treatment, plasma flavonols have been identified as conjugated quercetin itself, or a conjugated form (4.5-fold as abundant) of an aglycone less polar than quercetin. Rats fed quercetin or rutin diets had a green/yellow-colored plasma that exhibited a peak absorbance at 411 nm, vs. 363 or 375 nm for pure rutin or quercetin solutions, respectively. This shift of band I absorption was obtained when pure quercetin was in the presence of albumin or added to a plasma fraction. The bathochromic properties of flavonoids in the presence of albumin are highly dependent on the presence of the C-2/C-3 double bond on the C-ring and are influenced by the degree of B-ring hydroxylation. The existence of intermolecular bonds between albumin and quercetin is supported by in vitro absorbance and fluorescence studies. With human albumin, the fluorescence intensity and the shift of quercetin absorbance increased in parallel to the albumin/quercetin molar ratio. Conjugated diene formation, resulting from Cu(2+)-catalyzed oxidation of human LDL or rat VLDL+LDL was effectively inhibited in vitro by 0.5 mumol/L quercetin. These results show that dietary flavonols are recovered in rat plasma as conjugated metabolites in non-negligible concentrations, and that these flavonols may be interesting antioxidant micronutrients with a variety of biological effects.
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PMID:Quercetin metabolites in plasma of rats fed diets containing rutin or quercetin. 761 8

Tea has been shown to inhibit chemically induced tumorigenesis in many animal models, but the effects of tea consumption on human carcinogenesis are not conclusive. In order to develop biomarkers for tea consumption, we developed methods for the analysis of tea polyphenols in human plasma and urine samples using HPLC with the coulochem electrode array detection system. (-)-Epigallocatechin-3-gallate (EGCG), (-)-epigallocatechin (EGC), (-)-epicatechin-3-gallate (ECG), and (-)-epicatechin (EC) are the major polyphenols in green tea. Most of the tea polyphenols were in their conjugated forms in the plasma and urine. The samples were incubated with a mixture of beta-glucuronidase and sulfatase to generate the free form of tea polyphenols. After extraction into ethyl acetate and separation by reversed-phase chromatography, EGCG, EGC, and EC were identified on the basis of their retention times and electrochemical characteristics. Due to the high selectivity of the detection mode, interference was minimized. Good quantitative relationships were established for a large concentration range of tea polyphenols. The limits of detection for EGCG, EGC, ECG, and EC were from 0.5 to 1.5 ng/ml of plasma or urine sample. After ingestion of 1.2 g of decaffeinated green tea in warm water, the plasma samples collected at 1 h from 4 human volunteers contained 46-268 ng/ml of EGCG, 82-206 ng/ml of EGC, and 48-80 ng/ml of EC. ECG was not detected in plasma samples. The maximum urinary excretion of EGC and EC occurred at 3-6 h.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Analysis of plasma and urinary tea polyphenols in human subjects. 765 36


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