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PubMed1975

Pharmacokinetics of acetaminophen in the human neonate: formation of acetaminophen glucuronide and sulfate in relation to plasma bilirubin concentration and D-glucaric acid excretion.

The purpose of this study was to determine if certain physiologic parameters (plasma bilirubin concentration and urinary excretion rate of D-glucaric acid) can be used to predict a newborn infant's ability to eliminate a phenolic drug, and particularly to predict the ability to conjugate that drug with glucuronic acid. Tweleve healthy 2- to 3-day-old full-term infants with plasma bilirubin concentrations of 1.0 to 11.6 mg/100 ml and D-glucaric acid excretion rates of 0.131 to 0.345 mg/kg/day received a single oral dose of acetaminophen, 12 mg/kg. Urine was collected serially for 48 hours and analyzed for acetaminophen, acetaminophen glucuronide, acetaminophen sulfate, and D-glucaric acid. The biologic half-life of acetaminophen was 3.5 plus or minus 0.85 hours (average plus or minus SD) as compared to average values of 1.9 to 2.2 hours observed in five reported studies on a total of 39 adults. The rate constant for acetaminophen glucuronide formation in neonates was considerably smaller, on the average, than in adults but the average rate constant for acetaminophen sulfate formation was somewhat larger than in adults. There is not statistically significant colucaric acid excretion. The results of this study suggest that the limited ability of neonates to conjugate phenolic drugs with glucuronic acid is compensated to a degree by a well-developed capability for sulfate conjugation.

Acetaminophen↗
PubMed2005

Inhibition of human UDP-glucose dehydrogenase expression using siRNA expression vector in breast cancer cells.

UDP-glucose dehydrogenase (UGDH) catalyzes two oxidations of UDP-glucose to yield UDP-glucuronic acid. Pathological over-production of extracellular matrix components may be linked to the availability of UDP-glucuronic acid, therefore UGDH is a potential therapeutic target. RNA interference (RNAi) has been adapted to knock down the expression of human UGDH. A UGDH siRNA plasmid was constructed using a pRNA-U6.1/Neo vector and transfected into breast cancer cells, ZR-75-1, with an efficiency of up to 50%. Western blot analysis showed that the UGDH expression was efficiently knocked down at protein levels by RNAi in ZR-75-1 cells.

Breast Neoplasms↗
PubMed1988

Immunogenicity of liposome-bound hyaluronate in mice. At least two different antigenic sites on hyaluronate are identified by mouse monoclonal antibodies.

Hyaluronate (HA) was previously demonstrated to be immunogenic in rabbits. The immunogenicity of HA in mice was studied. Hyaluronidase-digested streptococcal HA (IA1) covalently linked to liposomes (IA1-liposomes) were produced for immunization. Mice immunized with IA1-liposomes developed measurable serum antibodies to IA1, while mice immunized with IA1 in Freund's adjuvant did not. mAbs produced by two stable hybridomas (10G6 and 5F11) from mice immunized with IA1-liposomes produced IgG antibody reactive with HA in ELISA. 10G6 had a much higher avidity for liposome-bound IA1 than free IA1, while 5F11 did not, suggesting that the mode of presentation of IA1 is important in HA immunogenicity and antigenicity. Both mAbs recognized terminal HA immunodeterminants exposed by hyaluronidase treatment. Sonication had no effect on HA reactivity for either mAb. However, ascorbic acid treatment significantly reduced the antigenicity of HA for mAb 5F11, but not 10G6. Only 10G6 was inhibited by glucuronic acid. Electrostatic forces appear to play a role in the binding site of 5F11, but not 10G6. 5F11 crossreacts with heparan sulfate and phosphorylcholine, while 10G6 did not crossreact with any glycosaminoglycans or phosphorylated compounds tested. These results confirm that HA is immunogenic. They suggest that the mode of presentation of HA is important for the induction of the immune response, and in HA antigenicity. At least two different antigenic sites on HA were demonstrated. 10G6 recognizes a terminal HA antigenic site expressed on IA1-liposomes that contains glucuronic acid in its immunodominant site. 5F11 recognizes an HA antigenic site in which electrostatic forces appear to play a role, is sensitive to ascorbic acid treatment, and is crossreactive with heparan sulfate. The use of mAbs should facilitate immunologic studies of HA.

Animals↗
PubMed2005

Assessment of UDP-glucuronosyltransferase catalyzed formation of ethyl glucuronide in human liver microsomes and recombinant UGTs.

While ethanol is primarily metabolized to acetaldehyde and acetic acid via alcohol dehydrogenase, a minor but increasingly important pathway in the field of forensic science involves the conjugation of glucuronic acid to form an ethyl glucuronide (EtG) metabolite. The kinetics of ethyl glucuronide formation were examined in human liver microsomes (HLM) and recombinant UDP-glucuronosyltransferases (UGTs). The metabolite exhibited a relatively slow rate of formation in a human liver microsome mix of 75.4 pmol/(min/mg). Further investigation identified multiple UGT isoforms to be responsible for catalyzing the addition of glucuronic acid to ethanol, with UGT1A1 and 2B7 being the two most prevalent isoforms. Co-incubation with bilirubin or 3'-azido-3'-deoxythymidine (UGT1A1 and 2B7 inhibitors, respectively) inhibited the greatest amount of ethyl glucuronide formation, though other UGT inhibitors also showed some effect. Enzyme kinetics were performed in human liver microsomes and recombinant UGT enzymes. The apparent Km (Km app) and Vmax values were determined to be 0.17+/-0.08 mM and 75.98+/-5.63 pmol/(min/mg) (human liver microsomes), 0.03+/-0.01 mM and 25.22+/-3.45 pmol/(min/mg) (UGT1A1), and 0.11+/-0.04 mM and 52.03+/-9.8 pmol/(min/mg) (UGT2B7). Thus, it appears that multiple UGTs are responsible for the formation of ethyl glucuronide and that any functional differences in the enzymology underlying ethyl glucuronide formation would most likely be masked by a combination of other enzymatic pathways.

Alcohol Drinking↗
PubMed1997

Novel tetrasaccharides isolated from squid cartilage chondroitin sulfate E contain unusual sulfated disaccharide units GlcA(3-O-sulfate)beta1-3GalNAc(6-O-sulfate) or GlcA(3-O-sulfate)beta1-3GalNAc.

We previously isolated novel tetrasaccharides containing 3-O-sulfated glucuronic acid from king crab cartilage chondroitin sulfate K and demonstrated that the disaccharide units containing 3-O-sulfated glucuronic acid were decomposed by chondroitinase ABC digestion (Sugahara, K., Tanaka, Y., Yamada, S., Seno, N., Kitagawa, H., Haslam, S. M., Morris, H. R., and Dell, A. (1996) J. Biol. Chem. 271, 26745-26754). The findings indicated the necessity to re-evaluate the disaccharide compositions of chondroitin sulfate preparations purified from other biological sources and analyzed using the above enzyme. In this study, to evaluate squid cartilage chondroitin sulfate E a series of even-numbered oligosaccharides were isolated after exhaustive digestion with sheep testicular hyaluronidase and subsequent fractionation by gel chromatography. The tetrasaccharide fraction was subfractionated by high performance liquid chromatography on an amine-bound silica column. Systematic structural analysis of five major fractions, h, l, m, n, and q, by fast atom bombardment mass spectrometry, enzymatic digestions in conjunction with capillary electrophoresis, and 500-MHz 1H NMR spectroscopy revealed one disulfated, three trisulfated, and one tetrasulfated tetrasaccharide structure: fraction h, GlcAbeta1-3GalNAc(4S)beta1-4GlcAbeta1-3GalNAc(4S); fraction l, GlcA(3S)beta1-3GalNAc(6S)beta1-4GlcAbeta1-3GalNAc(4S); fraction m, GlcA(3S)beta1-3GalNAc(4S)beta1-4GlcAbeta1-3GalNAc(4S); fraction n, GlcAbeta1-3GalNAc(4S,6S)beta1-4GlcAbeta1-3GalNAc(4S); and fraction q, GlcA(3S)beta1-3GalNAc(4S,6S)beta1-4GlcAbeta1-3GalNAc(4S), where 3S, 4S, and 6S represent 3-O-, 4-O- and 6-O-sulfate, respectively. The structures found in fractions h and m as well as the unsaturated counterpart of that found in fraction n have been reported, whereas those in fractions l and q are novel in that they contained unusual disulfated and trisulfated disaccharide units where GlcA(3S) is directly linked to GalNAc(6S) and GalNAc(4S,6S), respectively. These novel tetrasaccharide sequences are distinct from those found in other chondroitin sulfate isoforms and may play key roles in the biological functions and activities of chondroitin sulfate E not only from squid cartilage but also from mammalian cells and tissues.

Animals↗
PubMed1996

Cholesterol-independent membrane disruption caused by triterpenoid saponins.

The membrane-disrupting activity of 15 triterpenoid saponins, obtained from Chinese plants of the genus Aralia, was investigated using phosphatidylcholine liposomes with and without cholesterol. The permeability of the membrane was examined by monitoring the induced fluorescent dye release from the liposome. On the basis of the obtained results, the structure-activity relationship among glucuronides of oleanolic acid was discussed. This takes into account particularly the variation in the carboxyl function. Namely, the saponins could induce a permeability change on liposomal membrane without cholesterol when they are glycosylated at both C-3 and C-28 of the oleanolic acid. There also exists a great similarity in the time-course curves for dye-release within such saponins, reflecting their similar action with the lipid bilayer membrane. The saponins glycosylated only at C-3 could also exhibit the same activity with somewhat different action profiles when the glucuronic acid is esterified, while those with the free glucuronic acid required cholesterol in the liposomes to induce permeability change thereof.

Cholesterol↗
PubMed1980

Terminal monosaccharides of carbohydrate chains of glycosaminoglycans in normal human urine.

To elucidate the mode of the exertion of glycosidase activities in the catabolism of the tissue glycosaminoglycans (GAG), the terminal monosaccharides of the carbohydrate chains of urinary GAG in the most prominent subfraction (40% Fr-1.25 M Fr) among the subfractions obtained in a previous paper (Endo et al. 1980a) were investigated. The results of determination of the reducing hexuronic acid and N-acetylhexosamine before and after digestion of the subfraction with beta-glucuronidase and beta-N-acetylhexosaminidase, together with previous data indicated that 0.36 and 0.37 mol of glucuronic acid and N-acetylgalactosamine, respectively, per mol of the subfraction were located at the non-reducing terminals of the carbohydrate chains. The remaining portion (0.27 mol per mol) of the non-reducing ends might be mostly occupied by the sulfated N-acetylgalactosamine residues. On the other hand, 0.25, 0.16 and 0.34 mol of glucuronic acid, N-acetylgalactosamine and xylose, respectively, per mol of the subfraction were indicated to the present at the reducing terminals of the carbohydrate chains. The remaining portion (0.25 mol per mol) of the reducing ends might be mostly occupied by the galactose residues and/or the N-acetylgalactosamine 4-sulfate residues. The present observations provided with evidence for the action of endo-beta-glucuronidase and endo-beta-N-acetylhexosaminidase on the tissue GAG, specifically on chondroitin sulfates.

Glucuronates↗
PubMed1986

Diminished rates of glucuronidation and sulfation in perfused rat liver after chronic ethanol administration.

Rates of glucuronidation and sulfation of 7-hydroxycoumarin were studied in perfused livers from normal chow-fed rats, or in livers from rats that had been fed liquid control or ethanol-containing diets. During infusion of 100 microM 7-hydroxycoumarin, rates of glucuronidation were similar in livers from chow-fed or control diet rats, but were 34% less in livers from ethanol-fed rats. These rates of glucuronidation in perfused livers could not be explained by changes of UDP-glucuronyltransferase activity, which was highest in hepatic microsomes from ethanol-treated rats and lowest in microsomes from chow-fed rats. The low rates of glucuronidation in livers from ethanol-treated rats were correlated with low hepatic concentrations of UDP-glucuronic acid, which were less than 70% of the levels measured in the other treatment groups. However, the diminished UDP-glucuronic acid levels could not be explained by alterations in adenine nucleotides, NAD+/NADH ratios, glycogen, UDP-glucose, or activity of UDP-glucose dehydrogenase. Rates of sulfation declined during prolonged 7-hydroxycoumarin infusion in livers from ethanol-treated rats, but not in livers from rats that had received the control diet. Similarly, hepatic concentrations of adenosine-3'-phosphate 5'-sulfatophosphate (PAPS) also decreased with time only in livers from ethanol-treated rats. Thus, chronic ethanol feeding impairs glucuronidation and sulfation in perfused livers as a result of diminished availability of the required cofactors for these conjugation pathways.

Adenosine Triphosphate↗
PubMed1993

The cell wall of the oleaginous yeast Trichosporon cutaneum.

The cell wall of Trichosporon cutaneum consists of 11% protein, 63% neutral carbohydrate, 9% glucosamine and 13% glucuronic acid. The sugars include glucose (32%), mannose (6%) and traces of xylose and galactose. The cell wall was fractionated with alkali to yield a mixture of alkali-soluble matrix components, and an alkali-insoluble glucan associated with chitin. The alkali-insoluble glucan contained a mixture of (1-3) and (1-6) glycosidic linkages. It was only partly susceptible to digestion by the beta(1-3) glucanase, Zymolyase. The alkali-soluble fraction contained glucan, mannan and acidic polymers. The glucan was (1-3)-linked with no (1-6) linkages and only trace amounts of (1-3-6)-linked glucose. It was resistant to digestion by Zymolyase. Extensive hydrolysis of this fraction with trifluoroacetic acid released a high-molecular-mass glucuronan which had 1H- and 13C-NMR profiles matching those of the beta(1-4) glucuronan, mucoric acid. Xylomannan was purified from isolated cell walls and from whole cells. It contained glucose, mannose, xylose, and D-glucuronic acid. It was very similar in composition and structure to the capsular polysaccharides of Cryptococcus neoformans, and to an extracellular polysaccharide produced by another yeast described as T. cutaneum. Electron microscopy showed that the cell wall of T. cutaneum has a lamellar structure characteristic of a basidiomycetous yeast rather than the electron-dense 'fuzzy coat' seen in Candida albicans.

Candida albicans↗
PubMed1987

Glucuronoconjugates in chronic renal failure. Comparative determination with values in healthy adult.

We have isolated substances of molecular weight ranging between 350 and 2,000 daltons from ultrafiltrates of patients traited by maintenance haemodialysis for chronic renal failure (CRF). Such substances might have a role in the genesis of uremic toxicity. They were found to be glucuronoconjugates. We have studied 22 patients with CRF and 16 with end stage renal failure, 8 of them were traited by peritoneal dialysis, 8 by haemodialysis. We have evaluated the concentration of glucuronic acid in the serum, the urine and dialysis fluid. The patients with chronic renal failure have plasma levels of free and conjugate glucuronic acid higher than normal subjects. Urinary elimination is very lower in patient with CRF. Nevertheless the glucuronoconjugates are removed to a large extend by haemodialysis and peritoneal dialysis.

Glucuronates↗
PubMed2006

Lipids of 'Mycobacterium habana', a synonym of Mycobacterium simiae with vaccine potential.

'Mycobacterium habana' was proposed as a distinct species within the genus Mycobacterium; however, it is actually a synonym of Mycobacterium simiae and included in the serotype I of this species. The potential use of 'M. habana' as a vaccine in both leprosy and tuberculosis has led to the analysis of its lipid composition in an attempt to define distinctive markers that could be used in the quality control of true strains of this bacterium. Lipids of taxonomic value (fatty and mycolic acids) are similar in 'M. habana' and M. simiae; nevertheless, they clearly differ on the basis of glycopeptidolipid (GPL) composition. Thus, contrary to M. simiae, most strains of 'M. habana' can be defined by the presence of three polar compounds, designated GPL-I, GPL-II and GPL-III, easily determined by thin-layer chromatography, and characterized, respectively, by the content of l-fucose, 2,4-di-O-Me-d-glucuronic acid, and 4-O-Me-d-glucuronic acid, as epitopes.

Animals↗
PubMed1981

Comparative pharmacokinetics of aspirin and acetaminophen.

Aspirin is extensively hydrolyzed to salicylic acid during absorption after oral administration. This hydrolysis is completed systemically. Salicylic acid, an effective analgesic, antipyretic, and anti-inflammatory agent, is eliminated by renal excretion and by metabolic conversion to conjugates with glycine and glucuronic acid, respectively, and to gentisic acid. Two of these metabolic processes are easily saturable, causing systemic clearance of salicylate to decrease with increasing dose. Acetaminophen metabolism during absorption is minor, and the drug is eliminated primarily by conjugation with glucuronic acid and with sulfate to pharmacologically inactive products. These processes become saturated only in the supertherapeutic dose range, thereby causing an increase in the fraction in the dose converted to a minor but potentially hepatotoxic metabolite. In the usual therapeutic dose range, acetaminophen is much more rapidly eliminated from the body than is salicylic acid.

Acetaminophen↗
PubMed2001

Directly coupled HPLC-NMR and HPLC-MS approaches for the rapid characterisation of drug metabolites in urine: application to the human metabolism of naproxen.

High resolution nuclear magnetic resonance (NMR) spectroscopy is a very powerful tool for the structural identification of xenobiotic metabolites in complex biological matrices such as plasma, urine and bile. However, these fluids are dominated by thousands of signals resulting from endogenous metabolites and it is advantageous when investigating drug metabolites in such matrices to simplify the spectra by including a separation step in the experiment by directly-coupling HPLC and NMR. Naproxen (6-methoxy-alpha-methyl-2-naphthyl acetic acid) is administered as the S-enantiomer and is metabolised in vivo to form its demethylated metabolite which is subsequently conjugated with beta-D-glucuronic acid as well as with sulfate. Naproxen is also metabolised by phase II metabolism directly to form a glycine conjugate as well as a glucuronic acid conjugate at the carboxyl group. In the present investigation, the metabolism of naproxen was investigated in urine samples with a very simple sample preparation using a combination of directly-coupled HPLC-1H NMR spectroscopy and HPLC-mass spectrometry (MS). A buffer system was developed which allows the same chromatographic method to be used for the HPLC-NMR as well as the HPLC-MS analysis. The combination of these methods is complementary in information content since the NMR spectra provide evidence to distinguish isomers such as the type of glucuronides formed, and the HPLC-MS data allow identification of molecules containing NMR-silent fragments such as occur in the sulfate ester.

Buffers↗
PubMed1993

Molecular characterization of hasB from an operon required for hyaluronic acid synthesis in group A streptococci. Demonstration of UDP-glucose dehydrogenase activity.

The membrane-associated hyaluronate synthase produces capsular hyaluronate in group A streptococci by the alternate addition of UDP-N-acetylglucosamine and UDP-glucuronic acid. Previous studies identified a locus required for hyaluronate synthase activity and suggested that a gene involved in the production of UDP-glucuronic acid (UDP-glucose dehydrogenase) also mapped to the locus. In the present study the putative UDP-glucose dehydrogenase gene (hasB) was cloned and the DNA sequence determined. The hasB gene product was shown to have global similarity with AlgD, a dehydrogenase, which catalyzes the production of GDP-mannuronic acid for the alginate capsule of Pseudomonas aeruginosa. Regions of local homology have been identified which apparently correspond to the NAD-binding and enzyme active sites of HasB and AlgD. In order to show that hasB expression correlated with UDP-glucose dehydrogenase activity, the hasB gene was cloned under control of the T7 promoter. Hyperexpression of hasB resulted in a protein of approximately 47 kDa and high levels of UDP-glucose dehydrogenase activity were observed. These data demonstrate that hasB encodes the UDP-glucose dehydrogenase of group A streptococci.

Amino Acid Sequence↗
PubMedDate not supplied

Inosiplex: metabolism and excretion of the dimethylaminoisopropanol and p-acetamidobenzoic acid components in rhesus monkeys.

The principal excretion products derived from radiolabeled N,N-dimethylaminoisopropanol (Dip) and p-acetamidobenzoic acid (PAcBA) components of inosiplex (Isoprinosine) were identified and quantified in urine following single iv and oral administration of the drug in rhesus monkeys. The major metabolite derived from [3H] PAcBA was identified as PAcBA-O-acylglucuronide by 1) positive naphthorescorcinol reaction for glucuronic acid and 2) hydrolysis of the metabolite to PAcBA and glucuronic acid, using either dilute base (but not acid) or beta-glucuronidase. This metabolite accounted for 50% of the administered dose in orally dosed animals and 31% in iv dosed animals. A minor metabolite, which constituted approximately 5% of the excreted 3H from either iv or orally dosed animals, was identified as the hippuric acid conjugate of PAcBA by co-chromatography with a commercial standard. A single metabolite derived from [14C]Dip was identified as Dip-N-oxide by co-chromatography with synthetic material in several chromatographic systems; this metabolite accounted for 17 to 18% of the administered 14C in either the iv or orally dosed animals.

4-Aminobenzoic Acid↗
PubMedDate not supplied

Characterization of a carbamic acid ester glucuronide of the secondary amine sertraline.

In the dog, the major excretory metabolite of the antidepressant sertraline was characterized as sertraline carbamoyl-O-glucuronide. The intact conjugate was isolated from bile by HPLC. The metabolite was labile to beta-glucuronidase and produced sertraline as the single hydrolytic product, based on HPLC and GC-MS analyses. By fast atom bombardment MS analysis, [M+H]+ and [M+Na]+ ions at m/z 526 and 548 were observed, as were the proton and sodium adducts of the aglycone (m/z 350 and 372) due to cleavage of the glycosidic bond and elimination of the glucuronic acid moiety (176 amu). The observed mass of the aglycone was 44 amu greater than sertraline, indicating that a carbamic acid of this secondary amine was conjugated with glucuronic acid. These data suggest that sertraline in solution reversibly associates with CO2 before formation of sertraline carbamoyl-O-glucuronide. This novel amine glucuronide was also identified in human plasma after the oral administration of sertraline to each of seven subjects. The glucuronide was stable in plasma at both acidic and basic pH.

1-Naphthylamine↗
PubMed1983

The effect of choline deficiency on the activity of a phosphatidylcholine-requiring enzyme: activity and properties of UDP-glucuronyltransferase in choline-deficient rats.

The effect of choline deficiency on the kinetic properties of the microsomal enzyme UDP-glucuronyltransferase (EC2.4.1.17) was investigated in rats. Animals fed choline-deficient diets, as compared with animals fed a choline-replete diet or standard laboratory chow, showed almost a three-fold increase in enzyme activity when the enzyme was assayed at physiological concentrations of UDP-glucuronic acid (0.25 mM). The increase in activity appeared to be due to an enhanced affinity of the enzyme for UDP-glucuronic acid rather than to an increase in the amount of enzyme. These data indicate that the kinetic properties of tightly bound membrane enzymes are altered by a dietary change that is known to cause liver disease in the rat.

Animals↗
PubMedDate not supplied

[Lectin activity of antitumor substances synthesized by Bacillus subtilis B-7025].

Nutrient medium, which is optimal for synthesis of biologically active substances and allows obtaining stable outflow of Bacillus subtilis B-7025 to the culture medium, has been selected under the conditions of the bacillus periodic cultivation. It has been established that these substances are extracellular lectins with high activity and carbohydrate specificity to fructose-1.6-di phosphate, N-acetylneuraminic acid and glucose derivatives: D-glucuronic acid and D-glucosamine.

Antineoplastic Agents↗