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PubMed2003

Acyl glucuronidation and glucosidation of a new and selective endothelin ET(A) receptor antagonist in human liver microsomes.

Compound A [(+)-(5S,6R,7R)-2-isopropylamino-7-[4-methoxy-2-((2R)-3-methoxy-2-methylpropyl)-5-(3,4-methylenedioxyphenyl) cyclopenteno [1,2-b] pyridine 6-carboxylic acid] is a new and selective endothelin ET(A) receptor antagonist. It underwent significant acyl glucuronidation and acyl glucosidation in human liver microsomes supplemented with UDP-glucuronic acid (UDPGA) and UDP-glucose (UDPG). These two conjugations were observed in a panel of human liver microsomal samples (n = 16) that gave rise to varying activities but with no significant correlation with each other in the native and activator-treated microsomal preparations (r(2) 0.05). The lack of correlation may be explained by the involvement of multiple UDP-glucuronosyltransferases (UGTs; UGT1A1, 1A3, 1A9, 2B7 and 2B15) in the glucuronidation but essentially solely UGT2B7 in the glucosidation. Both reactions conformed to monophasic Michaelis-Menten kinetics in human liver microsomes. The glucuronidation reaction exhibited apparent K(m) values (mean +/- S.E.) for compound A and UDPGA of 8.4 +/- 0.6 and 605 +/- 35 microM, respectively, whereas the values for the glucosidation reaction were 10.2 +/- 1.5 and 670 +/- 120 microM, respectively. In both pooled human liver microsomes and expressed UGT2B7, UDPG and UDPGA competitively inhibited their counterpart conjugations with K(i) values close to their K(m) values, indicating a comparable affinity of the enzyme toward these two nucleotide sugars. We herein report a drug acyl glucoside formed in human liver microsomes at a considerable turnover rate and provide the evidence for a UGT isoform (UGT2B7) capable of transferring both glucuronic acid and glucose from UDPGA and UDPG to an aglycone.

Endothelin Receptor Antagonists↗

PubMed1974

Regulation of the beta-glucoside system in Escherchia coli K-12.

In Escherichia coli wild-type cells, a mutation at the beta-glucoside regulatory gene (bglR(+) to bglR(-)) leads to simultaneous expression of inducible phospho-beta-glucosidase B (bglB(+)) and a beta-glucoside-specific species of enzyme II (beta-glucoside transport I [bglC(+)]); an additional mutation (bglS(+) to bglS4) allows these enzymes to be formed constitutively. The bgl alleles have been mapped in the following order: pyrE, bglA, bglB, bglS, bglR, bglC, ilvD. The back mutation in the regulatory allele (bglR(-) to bglR(+)) caused the cessation of the expression of the bglB(+), bglS(+) or bglS4, bglC(+) alleles. However, a mutation in a strain with bglB(+), bglS4, bglR8, bglC(+) alleles, at the ini site that lies between the bglS4 and the bglR8 allele, allowed the expression of the bglS4 and bglB(+) alleles, but showed no affect on the expression of the bglC(+) allele. It is suggested that the ini mutation possesses a promotor-type function that in the absence of regulatory allele function (bglR8) renews the functioning of only the bglS4 and bglB(+) alleles. The complementation studies have shown that the bglB(+), bglS(+) or bglS4, bglC(+) alleles are expressed only in cis to the bglR(-) allele. In the constitutive strain (bglB(+), bglS4, bglR(-), bglC(+)), the expressed bglS4 allele formed a soluble product that acts in trans over the bglB(+) and bglC(+) alleles and that appears effective only when the bglB(+) and the bglC(+) alleles are expressed in cis to the bglR(-) allele. It thus showed that the constitutive biosynthesis of phospho-beta-glucosidase B and beta-glucoside transport I is under positive control. Since the regulatory allele bglR(-) lies between the bglS4 and the blgC(+) alleles, and acts in cis, it appears that the mutation (bglR(+) to bglR(-)) allows the initiation of transcription in one direction to express the bglS4, bglB(+) alleles and in the other to express the bglC(+) allele. The structural genes bglB and bglC lie adjacent to the regulatory genes bglR and bglS, and the structural genes are coordinately controlled by the regulatory genes. It is, therefore, proposed that the bglB, bglS, bglR, bglC genes form a bgl operon.

Alleles↗

PubMed1990

Analysis of the Erwinia chrysanthemi arb genes, which mediate metabolism of aromatic beta-glucosides.

Erwinia chrysanthemi is one of the few members of the family Enterobacteriaceae that is capable of metabolizing most of the naturally occurring beta-glucosides. We previously isolated the clb genes, which allow the use of the disaccharide cellobiose as well as the aromatic beta-glucosides arbutin and salicin. We report here the isolation of the arb genes, which permit fermentation of the aromatic beta-glucosides only. Establishment of a functional Arb system in Escherichia coli depended on the presence of the phosphotransferase system and on the activation by the cyclic AMP-cyclic AMP receptor protein complex. Strains carrying mini-Mu-induced LacZ fusions to the arb genes were used to analyze arb genes organization and function. Three arb genes (arbG, arbF, and arbB) were identified and organized in this order. Genetic and structural evidence allowed us to assign a phospho-beta-glucosidase and a permease activity to the ArbB and ArbF proteins, respectively. Several Lac+ arb-lacZ insertions were introduced into the E. chrysanthemi chromosome. Both ArbG- and ArbF- strains were unable to ferment the aromatic beta-glucosides, whereas ArbB- strains were impaired only in salicin fermentation. None of the mutations in the arb genes affected cellobiose metabolism. The expression of the arb genes was substrate inducible and required the ArbF permease and, possibly, the ArbG protein. Collectively, our results underline the resemblance between the naturally expressed E. chrysanthemi arbGFB and the cryptic E. coli bglGFB operons, yet the arbG gene product seemed unable to activate E. coli bgl operon expression.

Cloning, Molecular↗

PubMed2001

In vitro evaluation of secoiridoid glucosides from the fruits of Ligustrum lucidum as antiviral agents.

Six secoiridoid glucosides, lucidumoside C (1), oleoside dimethylester (2), neonuezhenide (3), oleuropein (4), ligustroside (5) and lucidumoside A (6), isolated from the fruits of Ligustrum lucidum (Oleaceae), were examined in vitro for their activities against four strains of pathogenic viruses, namely herpes simplex type I virus (HSV-1), influenza type A virus (Flu A), respiratory syncytial virus (RSV) and parainfluenza type 3 virus (Para 3). Antiviral activities were evaluated by the cytopathic effect (CPE) inhibitory assay. The purpose was to check if the antioxidative potency of these glucosides correlated with their antiviral potency. Results showed that none of the glucosides had any significant activity against HSV-1 and Flu A. Oleuropein, however, showed significant antiviral activities against RSV and Para 3 with IC50 value of 23.4 and 11.7 microg/ml, respectively. Lucidumoside C, oleoside dimethylester and ligustroside showed potent or moderate antiviral activities against Para 3 with IC50 values of 15.6-20.8 microg/ml. These results also documented that the anti-oxidative potency of these secoiriodoid glucosides was not directly related to their antiviral effects.

Animals↗

PubMedDate not supplied

Dorycnioside, a new phenylbutanone glucoside from Dorycnium pentaphyllum subsp. herbaceum.

A new phenylbutanone glucoside, dorycnioside, was isolated from the methanol extract of the aerial parts of Dorycnium pentaphyllum subsp. herbaceum Vill. (Rouy) and identified as 4-(4'-O-beta-D-glucopyranosyl-3',5'-dimethoxyphenyl)-2-butanone (1). In addition, two known phenylbutanone glucosides, five flavonoids, one cyanogenic glucoside, one cyclitol and one hydroquinone glucoside were also isolated and identified. The major constituent of the methanol extract was found to be myricitrin. The structure of 1 was elucidated on the basis of its spectroscopic data. It is the first time that derivatives of phenylbutanone are isolated from the Leguminosae family.

Butanones↗

PubMed1979

[Interrelationship between glucoside-bound and free alcohols during ether oil formation in rose petals].

Some data on the dynamics of free and glucoside-bound monoterpenic and aromatic (beta-phenylethyl) ethers content and the changes in the beta-glucosidase activity in rose petals at different stages of the flower development and on the kinetics of enzymatic hydrolysis of these glucosides are presented. The phase specificity of beta-glucosidase coinciding with the maximal accumulation of glucoside-bound and free alcohols is revealed. The data obtained suggest that the formation of glucosides may precede the accumulation of corresponding free alcohols of terpenic and aromatic origin.

Alcohols↗

PubMed1999

[Separation and identification of flavonoid glucosides from Elsholtzia blanda (Benth.) Benth].

OBJECTIVE: To study chemical elements of the inflorescence of Elsholtzia blanda produced in the southwest of Yunnan. METHOD: Using chemical techniques and spectroscopic analysis. RESULT: Four flavonoid glucosides from the water extract of E. blanda were isolated and identified as isoastragalin(I), luteolin-7-glucoside(II), luteolin-3'-glucoside(III) and lutelin-7-galactoside(IV). CONCLUSION: All the four flavonoid glucosides were isolated from the plant for the first time.

Flavonoids↗

PubMed2003

[Study on the metabolite of stilbene glucoside in mice by liquid chromatography tandem-mass spectrometry].

AIM: To study the metabolite of stilbene glucoside in the Chinese traditional medicine Polygonum multiflornm in mice and elucidate its chemical structure by liquid chromatography tandem-mass spectrometry. METHODS: The stilbene glucoside was injected into the tail vein of mice. Blood samples were collected from artery in the eyepit. The methanol-protein-precipitated plasma sample was introduced into the liquid chromatography-tandem mass spectrometer directly. The analytical column was C18 column (250 mm x 4.6 mm ID, 5 microns). The mobile phase consisted of acetonitrile-methanol-water-formic acid (15:18:66:1) for ES+, acetonitrile-methanol-water (15:18:67) for ES-. The UV detection wavelength was set at 320 nm. The mass ion source type was ESI. HV capillary was 3 kV. The dry gas was nitrogen gas and the flow rate was set at 318 L.h-1. The ion source temperature was 150 degrees C. RESULTS: The stilbene glucoside and its metabolite were separated completely under the chromatography condition. The ions at m/z 600 and m/z 605 were detected under positive ion polarity while the ions at m/z 581 and m/z 402 were detected under negative ion polarity. CONCLUSION: It was proposed that the metabolite of stilbene glucoside injected in vein was its glucuronide conjugate.

Animals↗

PubMed2005

[Determination of 2,3,5,4'-tetrahydroxystilbene-2-O-beta-D-glucoside in the traditional Chinese preparation by high performance liquid chromatography with chemiluminescence detection].

Based on the chemiluminescence reaction of KMnO4-HNO3-2,3,5,4'-tetrahydroxystilbene-2-O-beta-D-glucoside sensitized by HCHO, an analytical method for 2,3,5,4'-tetrahydroxystilbene-2-O-beta-D-glucoside by RP-HPLC with chemiluminescence detector was developed. The chromatographic conditions were optimized. AN ODS hypersil column(25 mm x 4.0 mm, 125 x 4.0 mm i.d. 5 microm) was used with acetonitrile--0.3% H3PO4 [25:75, (phi)] as mobile phase, and the flow rate was 0.8 mL x min(-1) at the column temperature of 40 degrees C. The linear range of calibration curve was from 15.75 to 136.5 microg x mL(-1), the detection limit was 11.83 microg x mL(-1) with a concentration of 21 microg x mL(-1) of 2,3,5,4'-tetrahydroxystilbene-2-O-beta-D-glucoside, and the recovery was 102%-108%. The relative standard deviation was 3.45% (Cs = 21.0 microg x mL(-1), n = 3). The method has been applied to the determination of 2,3,5,4'-tetrahydroxystilbene-2-O-beta-D-glucoside in a few Chinese medicines, and the results were satisfactory. The method was simple, rapid and highly selective.

Capsules↗

PubMed1992

Exolytic hydrolysis of toxic plant glucosides by guinea pig liver cytosolic beta-glucosidase.

We demonstrate that although the guinea pig liver cytosolic beta-glucosidase does not catalyze the hydrolysis of gentiobiose, it does hydrolyze, disaccharide-containing glycosides such as p-nitrophenyl-beta-D-gentiobioside (Glc beta 1----6Glc beta-pNP) and mandelonitrile-beta-D-gentiobioside (amygdalin). Furthermore, we establish that the enzyme attacks disaccharide glycosides exolytically; specifically, we document the exolytic deglucosylation of amygdalin and the generation of the intermediate monosaccharide glycoside mandelonitrile-beta-D-glucoside prior to the formation of the aglycone (mandelonitrile). We also show that the cytosolic beta-glucosidase catalyzes the hydrolysis of various phenolic (e.g. arbutin and salicin) and cyanogenic plant glucosides (e.g. prunasin). Using the everted gut-sack technique, we demonstrate that the plant glucosides, amygdalin, prunasin, and vicine, are transported across the small intestine of the guinea pig efficiently and without being hydrolyzed. Based on these data we speculate that the cytosolic beta-glucosidase may participate in biotransformation of toxic plant glucosides.

Amygdalin↗

PubMed2006

[Preparation of soybean isoflavone glucosides by reversed-phase high performance liquid chromatography].

A method was established for the isolation of soybean isoflavone glucosides from the total isoflavone extracts of soybean using preparative reversed-phase high performance liquid chromatography (RP-HPLC). The total isoflavone extracts were separated into four parts by solvent extraction, those are the ethyl acetate extract, butanol extract, precipitate (D4), and the remaining aqueous phase. The part D4 containing soybean isoflavone glucosides was acquired and subjected to preparative HPLC for the isolation of target components. A preparative Nova-Pak HR C18 column (100 mm x 25 mm i. d. , 6 microm) was used in the preparation process. By isocratic elution with methanol-0.1% aqueous acetic acid (23:77, v/v) as the mobile phase at a flow rate of 20 mL/min, followed by concentration and desalination, three soybean isoflavone glucosides were obtained and subsequently identified by mass spectrometry as daidzin, glycitin, and genistin. HPLC analysis showed that the purities of the three soybean isoflavone glucosides were all higher than 99%.

Chromatography, High Pressure Liquid↗

PubMed1991

Identification of phenobarbital N-glucosides as urinary metabolites of phenobarbital in mice.

Previously, the N-glucosylation of phenobarbital had been observed only in humans. The results of a species screen (mouse, rat, guinea pig, rabbit, cat, dog, pig, and monkey) found that only mice excreted the N-glucosides of phenobarbital in urine after ip administration of sodium phenobarbital. The major diastereomer excreted by the mouse had the R configuration at the C-5 position of the barbiturate ring. The N-glucoside metabolites accounted for a small percentage of the dose (approximately 0.5%). Following ip dosing of the mouse with the phenobarbital N-glucosides, free phenobarbital could be detected in the urine. Upon ip or intercerebroventricular (icv) injection of the phenobarbital N-glucosides, minimal CNS activity was observed in the mouse.

Animals↗

PubMed1996

Oxidation products of cyanidin 3-O-beta-D-glucoside with a free radical initiator.

Recently, we have reported that anthocyanins show strong antioxidative activity, but no attention has been paid to anthocyanins from the viewpoint of the reaction mechanism of alkylperoxyl radicals; therefore, we investigated the reaction products of antioxidative anthocyanins (cyanidin 3-O-beta-D-glucoside). Cyanidin 3-O-beta-D-glucoside was reacted with 2,2'-azobis(2,4-dimet hylvaleronitrile) to generate the alkylperoxyl radicals, and the reaction products were isolated by high-performance liquid chromatography. The products were identified as 4,6-dihydroxy-2-O-beta-D-glucosyl-3-oxo-2,3-dihydroben-zofuran+ ++ and protocatechuic acid. Based on reaction products, the antioxidative mechanism of cyanidin 3-O-beta-D-glucoside may be different from that of alpha-tocopherol; cyanidin 3-O-beta-D-glucoside would produce another radical scavenger, as it would break down the structure and scavenge the radicals.

Anthocyanins↗

PubMed1999

Anaerobic transformation of quercetin-3-glucoside by bacteria from the human intestinal tract.

From human feces two phenotypically different types of bacteria were isolated on quercetin-3-glucoside as carbon and energy source. Isolates of one type were identified as strains of Enterococcus casseliflavus. They utilized the sugar moiety of the glycoside, but did not degrade the aglycon further. The sugar moiety (4 mM) was fermented to 5.5 +/- 2.1 mM formate, 2.1 +/- 0.7 mM acetate, 1.6 +/- 0.3 mM l-lactate, and 1.3 +/- 0.4 mM ethanol. The second type of isolate was identified as Eubacterium ramulus. This organism was capable of degrading the aromatic ring system. Growing cultures of Eubacterium ramulus converted 5 mM quercetin-3-glucoside to 1.7 +/- 0.6 mM 3,4-dihydroxyphenylacetic acid, 7.6 +/- 1.0 mM acetate, and 4.0 +/- 0.4 mM butyrate. Molecular hydrogen, 3,4-dihydroxybenzaldehyde, and ethanol were detected in small amounts. Phloroglucinol was a transient intermediate in the breakdown of quercetin-3-glucoside. Eubacterium ramulus did not grow on the aglycon quercetin or the ring-fission intermediate phloroglucinol, but cleaved the flavonoid ring system when glucose was present as a cosubstrate. The most probable number of quercetin-3-glucoside-degrading bacteria determined in nine human fecal samples was 10(7)-10(9)/g dry mass. Isolates from these experiments were all identified as Eubacterium ramulus.

Anaerobiosis↗

PubMed2000

Identification of high-affinity binding sites for the hepta-beta-glucoside elicitor in membranes of the model legumes Medicago truncatula and Lotus japonicus.

Previous studies have led to the identification and characterization of specific, high-affinity binding sites for a hepta-beta-glucoside elicitor in soybean. A survey of plant species for elicitor-binding activity reveals that among the plants tested, the hepta-beta-glucoside elicitor is only recognized by plants belonging to the legume family. We have characterized in detail the glucan elicitor-binding site in the model legume Medicago truncatula Gaertn., and partially characterized the site in Lotus japonicus. These sites have characteristics that are very similar to the one in soybean, with dissociation constants of 4.7 and 8.9 nM respectively. The elicitor-binding sites from both plants are stable during solubilization with non-ionic alkylglycoside detergents. However, differences are observed in the abundance of the binding sites and their selectivity towards structurally related analogues of the hepta-beta-glucoside elicitor. Our results suggest that similar, but perhaps not identical, binding sites for the hepta-beta-glucoside elicitor exist in diverse legumes, but not in plants outside of the legume family.

Binding Sites↗

PubMed1985

Actions of flavonoids and the novel anti-inflammatory flavone, hypolaetin-8-glucoside, on prostaglandin biosynthesis and inactivation.

The newly identified plant-derived flavone-glycoside hypolaetin-8-glucoside, which has anti-inflammatory and gastric ulcer protective properties, and its corresponding aglycone, hypolaetin, were tested for effects on prostaglandin biosynthesis and degradation. They were compared with four other flavonoids, viz. rutin and its corresponding aglycone, quercetin, and the aglycones isoscutellarein and kaempferol. Over the range 10-1000 microM the glycosides rutin and hypolaetin-8-glucoside stimulated prostaglandin formation by sheep seminal vesicle microsomes incubated with radiolabelled arachidonic acid; the other compounds were essentially inactive. Over 5-5000 microM rutin and hypolaetin-8-glucoside enhanced the release of prostacyclin (and other prostanoids) from fragments of rat caecum incubated in the absence of additional arachidonic acid; the four aglycones compounds did not stimulate prostacyclin release but some reduced it at 5000 microM. However, the glycosides did not affect the enzymatic inactivation of radiolabelled prostaglandin F2 alpha by semi-purified bovine lung prostaglandin 15-hydroxydehydrogenase (PGDH) or in 100,000 g supernatants prepared from homogenised rat stomach. Three of the four aglycones (quercetin, kaempferol, isoscutellarein, in descending order of potency) were inhibitory to PGDH with ID50 values in the range 130-2100 microM. The results show that the capacity of flavonoids to enhance prostaglandin formation is associated with the presence of glycosidic substitution, whereas PGDH inhibition requires its absence. The relevance of this biochemical profile of hypolaetin-8-glucoside to its anti-inflammatory gastroprotective effects in vivo is discussed.

Animals↗

PubMed1990

Drug glucosidation.

A number of studies have shown that drug glucosidation occurs in vertebrates. This review summarizes information on the chemical, physical and biological properties of eleven drug glucosides. Three out of two hundred individuals exhibited a complete lack of amobarbital-N-glucoside formation. The data from a pair of identical twins who were deficient in this metabolic pathway suggested the presence of a recessive trait controlled by a single pair of autosomal genes which regulate N-glucoside formation. In addition, average values seemed to be subject to interethnic variation.

Animals↗

PubMed2004

Purification and characterization of Acremonium implicatum alpha-glucosidase having regioselectivity for alpha-1,3-glucosidic linkage.

alpha-Glucosidase with a high regioselectivity for alpha-1,3-glucosidic linkages for hydrolysis and transglucosylation was purified from culture broth of Acremonium implicatum. The enzyme was a tetrameric protein (M.W. 440,000), of which the monomer (M.W. 103,000; monomeric structure was expected from cDNA sequence) was composed of two polypeptides (M.W. 51,000 and 60,000) formed possibly by posttranslational proteolysis. Nigerose and maltose were hydrolyzed by the enzyme rapidly, but slowly for kojibiose. The k(0)/K(m) value for nigerose was 2.5-fold higher than that of maltose. Isomaltose was cleaved slightly, and sucrose was not. Maltotriose, maltotetraose, p-nitrophenyl alpha-maltoside and soluble starch were good substrates. The enzyme showed high affinity for maltooligosaccharides and p-nitrophenyl alpha-maltoside. The enzyme had the alpha-1,3- and alpha-1,4-glucosyl transfer activities to synthesize oligosaccharides, but no ability to form alpha-1,2- and alpha-1,6-glucosidic linkages. Ability for the formation of alpha-1,3-glucosidic linkage was two to three times higher than that for alpha-1,4-glucosidic linkage. Eight kinds of transglucosylation products were synthesized from maltose, in which 3(2)-O-alpha-nigerosyl-maltose and 3(2)-O-alpha-maltosyl-maltose were novel saccharides.

Acremonium↗