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At least 235 records · Page 13Linked to original sources

PubMed1995

Effect of ultraviolet-A (UV-A) light on growth, photosynthetic activity and production of biopterin glucoside by the marine UV-A resistant cyanobacterium Oscillatoria sp.

We have isolated a marine planktonic cyanobacterium Oscillatoria sp. NKBG 091600 which is resistant to ultraviolet-A (UV-A) irradiation. In response to UV-A irradiation this cyanobacterium produces high levels of a UV-A absorbing compound which was identified previously as biopterin glucoside. Here, we have investigated the effect of UV-A light intensity on growth, biopterin glucoside production and photosynthetic activity. Oscillatoria sp. NKBG 091600 could grow at UV-A intensities of up to 800 microW/cm2 and at 300 microW/cm2 could grow as well as in the absence of UV-A irradiation. In addition, pre-culture of cells with UV-A protected cells from UV-A induced inhibition of photosynthetic activity. Detection of biopterin glucoside levels in irradiated cells by HPLC demonstrated that after 10 h there was a rapid increase in biopterin glucoside content. This increase was dependent on the intensity on the intensity of the UV-A irradiation.

Biopterins↗

PubMed1991

Barbital N-glucoside is not detected as a urinary excretion product of barbital in humans.

A study was undertaken to determine if humans excreted barbital N-glucoside as a urinary metabolite following oral administration of barbital. A liquid chromatography method using gradient elution was developed for detecting and quantifying barbital N-glucoside and barbital in urine. Following a single oral dose of barbital to male caucasian and oriental subjects that had previously been shown to excrete amobarbital and phenobarbital N-glucosides, no barbital N-glucoside conjugate was observed in the urine. This result indicates that N-glucosylation of barbiturates is not a general pathway for the biodisposition of barbiturates in man.

Administration, Oral↗

PubMed2003

Charge equilibria and pK(a) of malvidin-3-glucoside by electrophoresis.

Paper electrophoresis has been used over the pH range 1.2 to 10.4 to measure apparent pK(a) values for malvidin-3-O-glucoside of pK(a(1)) 1.76+/-0.07, pK(a(2)) 5.36+/-0.04, and pK(a(3)) 8.39+/-0.07. Using solvent partitioning between buffered aqueous solutions and n-octanol, several micro-pK(a) constants for malvidin-3-O-glucoside were also identified, highlighting the complex nature of malvidin-3-glucoside equilibria. As a nonspectrophotometric procedure, the charge-dependent electrophoretic mobility method provided independent information on the net charge and color of anthocyanin species at wine pH (ca. 3.6). At this pH, the color of malvidin-3-glucoside in red wines is consistent only with the uncharged quinonoidal base as a major colored component of the equilibria.

Anthocyanins↗

PubMed2002

Synergistic antioxidant effect of catechin and malvidin 3-glucoside on free radical-initiated peroxidation of linoleic acid in micelles.

The inhibitory effect of anthocyanins has been investigated in the peroxidation of linoleic acid in micelles in the presence and in the absence of (+)-catechin. The peroxidation was initiated by thermal decomposition of 2,2(')-azobis[2-(2-imidazolin-2-yl)propane], and the kinetics of peroxidation were followed by measuring the rate of oxygen consumption and the rate of disappearance of the antioxidant. The analysis of the antioxidant effect of various anthocyanins, alone or in the presence of catechin, demonstrates that catechin, which is relatively inefficient at inhibiting linoleic acid oxidation, regenerates the highly efficient antioxidant malvidin 3-glucoside and, at a lower extent, peonidin 3-glucoside. The malvidin 3-glucoside recycling by catechin strongly increases the antioxidant efficiency of these two antioxidants. This protective mechanism appears specific for malvidin and peonidin 3-glucosides. The high unpaired spin density of the phenolic O atoms in the radicals generated by these anthocyanins, calculated by the semiempirical quantum chemical AM1 method, may explain the observed behavior.

Anthocyanins↗

PubMed1998

Transport of quercetin and its glucosides across human intestinal epithelial Caco-2 cells.

There is mounting evidence from human epidemiological, animal in vivo, and in vitro studies to suggest beneficial effects related to the consumption of quercetin and its glucosides. However, there is limited knowledge on the oral bioavailability of these natural products. This study examined the intestinal epithelial membrane transport of quercetin, quercetin 4'-glucoside, and quercetin 3,4'-diglucoside, using the Caco-2 human colonic cell line, a model of human intestinal absorption. The apparent permeability (Papp) of each agent was measured in both apical to basal and basal to apical directions. The apical to basolateral flux of quercetin, Papp 5.8 +/- 1.1 x 10(-6) cm x sec(-1) (mean +/- SEM), was more than 10-fold higher than for the paracellular transport marker mannitol, 0.48 +/- 0.09 x 10(-6) cm x sec(-1) (P < 0.01). Under identical conditions, the Papp for the transcellular marker propranolol was about 5-fold higher than for quercetin (P < 0.001). Interestingly, the reverse, basolateral to apical, flux of quercetin (Papp 11.1 +/- 1.2 x 10(-6) cm x sec(-1)) was almost 2-fold higher than the apical to basolateral flux (P < 0.001). In similar experiments, quercetin 4'-glucoside demonstrated no absorption, Papp < 0.02 x 10(-6) cm x sec(-1) in the apical to basal direction, but did demonstrate basal to apical flux, Papp 1.6 +/- 0.2 x 10(-6) cm x sec(-1). Quercetin 3,4'-diglucoside showed a low apical to basolateral transport (Papp 0.09 +/- 0.03 x 10(-6) cm x sec(-1)); its reverse, basolateral to apical, transport was, however, 4-fold higher (P < 0.05). In these cells, glucose was actively transported with an apical to basolateral Papp of 36.8 +/- 1.1 x 10(-6) cm x sec(-1). These observations suggest facile absorption of quercetin through the human intestinal epithelium, but contrary to a previous proposal, they do not support an active transport process for quercetin glucosides.

Caco-2 Cells↗

PubMed2001

Colorimetric determination of active alpha-glucoside transport in Saccharomyces cerevisiae.

Fermentation of alpha-glucosides (maltose, maltotriose) by Saccharomyces cerevisiae cells is a critical phase in the processes of brewing and breadmaking. Utilization of alpha-glucosides requires the active transport of the sugar across the cell membrane and, subsequently, its hydrolysis by cytoplasmic glucosidases. Although transport activities are usually assayed using radiolabeled substrates, we have developed a simple, cheap and reliable colorimetric assay for the determination of alpha-glucoside uptake using p-nitrophenyl-alpha-D-glucopyranoside (pNPalphaG) as substrate. Our results show that pNPalphaG is actively transported by S. cerevisiae cells by a H+-symport mechanism, which depends on the electrochemical proton gradient across the plasma membrane. pNPalphaG uptake is mediated by the AGT1 alpha-glucoside permease, which has a high affinity (Km=3 mM) for this chromogenic substrate. This simple colorimetric uptake assay can be used to analyze the expression and regulation of the AGT1 permease in S. cerevisiae cells.

Biological Transport, Active↗

PubMed1986

Interaction of tubulin with octyl glucoside and deoxycholate. 2. Protein conformation, binding of colchicine ligands, and microtubule assembly.

The structural change induced by binding of mild detergents to cytoplasmic calf brain tubulin and the effects on the functional properties of this protein have been characterized. Massive binding of octyl glucoside or deoxycholate monomers induces circular dichroism changes indicating a partial alpha-helix to disordered structure transition of tubulin. The protein also becomes more accessible to controlled proteolysis by trypsin, thermolysin, or V8 protease. This is consistent with the looser protein structure proposed in previous binding and hydrodynamic studies [Andreu, J. M., & Muñoz, J. A. (1986) Biochemistry (preceding paper in this issue)]. Micelles of octyl glucoside and deoxycholate bind colchicine and its analogue 2-methoxy-5-(2,3,4-trimethoxyphenyl)-2,4,6-cycloheptatrien-1-one (MTC). This impedes the determination of colchicine binding in the presence of detergents. Both detergents cause a reduction in the number of tubulin equilibrium binding sites for the colchicine site probe MTC. Deoxycholate monomers bind poorly to the tubulin-colchicine complex, but deoxycholate above the critical micelle concentration effectively dissociates the complex. Microtubule assembly in glycerol-containing buffer is inhibited by octyl glucoside, which raises the critical protein concentration. Low concentrations of deoxycholate enhance tubulin polymerization, allowing it to proceed without glycerol. The polymers formed are microtubules, pairwise associated open microtubular sheets, and macrotubules possibly generated by helical folding of the sheets, as indicated by the optical diffraction patterns. Saturation of tubulin with octyl glucoside, followed by full dissociation of the detergent, allowed the recovery of binding to the colchicine site and microtubule assembly, indicating the reversibility of the protein structural change.

Animals↗

PubMed2002

Interactions between cyanidin 3-O-glucoside and furfural derivatives and their impact on food color changes.

The reaction between (+)-catechin and cyanidin 3-O-glucoside was investigated in the presence of furfural and 5-(hydroxymethyl)furfural using LC/DAD and LC/MS analysis, and the obtained results were compared with those recorded with malvidin 3-O-glucoside. The appearance of colorless and red and yellow compounds was observed showing that the two polyphenols competed in the condensation process with a predominant formation of the reddish adducts. The colored compounds formed in the case of cyanidin 3-O-glucoside seemed to be more stable than those formed when the reaction was conducted with malvidin 3-O-glucoside. The detection of these reddish and yellowish compounds constitutes a new support for the contribution of this kind of reaction in the color evolution of fruit-derived beverages. In addition, other unidentified compounds were also detected, showing the occurrence of other interaction pathways in addition to the polymerization process yielding oligomeric bridged derivatives and opening perspectives of further investigations of these model solutions.

Anthocyanins↗

PubMed2005

Flavonol glucoside profile of southern Italian red onion (Allium cepa L.).

High-performance liquid chromatography-diode array detector (HPLC-DAD) coupled with electron spray mass spectrometry (ESI-MS-MS) was used to determine the flavonol profile in southern Italian red onions (Allium cepa L.). This on-line technique allowed the identification of seven flavonols in southern Italian red onion, quercetin 4'-glucoside and quercetin 3,4'-diglucoside being the most abundant components. Five minor flavonols have been recognized, offering a characteristic profile of such compounds in red onions under study. Quercetin 3-glucoside, quercetin 7,4'-diglucoside, quercetin 3,7,4'-triglucoside, and isorhamnetin 4'-glucoside have been previously reported as minor flavonoid components in Allium cepa, while isorhamnetin 3,4'-diglucoside was previously found in Allium ascalonicum. Traces of isorhamnetin 3-glucoside and free quercetin were also detected.

Chromatography, High Pressure Liquid↗

PubMed2004

Production of bioavailable flavonoid glucosides in fruit juices and green tea by use of fungal alpha-L-rhamnosidases.

Flavonoid glucosides have been reported to be more bioavailable than their rutinoside counterparts. The aim of this study is to describe a first step in the use of alpha-L-rhamnosidases (RhaA and RhaB) from Aspergillus aculeatus as a way to produce functional beverages based on their potentially increased flavonoid bioavailability. Blackcurrant juice (BCJ), orange juice (OJ), and green tea infusion (GT) were incubated with either RhaA or RhaB at 30 degrees C for 10 h. Aliquots of controls and enzyme-treated samples were taken at different time points and analyzed by high-performance liquid chromatography-photodiode-array detector-mass spectrometry of daughter fragments (HPLC-DAD-MS-MS). Both RhaA and RhaB selectively catalyze in situ the removal of terminal rhamnosyl groups in the three beverages despite the heterogeneity of assay conditions such as different rutinosides and pH. Incubation of the three beverages with the two rhamnosidases resulted in a hyperbolic decrease in the flavonoid rutinosides (anthocyanins in BCJ, flavanones in OJ, and flavonols in GT) and a concomitant increase in their flavonoid glucoside counterparts. The time required for conversion of 50% of the rutinoside into the corresponding flavonoid glucoside ranged from 30 min (RhaB-rutin in GT) to 6 h (RhaB-delphinidin 3-rutinoside in BCJ). The results presented in this paper are a step forward in the use of enzyme-treated beverages as a source of bioavailable flavonoid glucosides.

Aspergillus↗

PubMed2004

Structural characterization of new malvidin 3-glucoside-catechin aryl/alkyl-linked pigments.

The condensation reaction between malvidin 3-glucoside and catechin mediated by isobutyraldehyde, benzaldehyde, and isovaleraldehyde was conducted in model solutions at two pH values (1.5 and 3.2). The formation of new alkyl/aryl-linked adducts corresponding to the structures malvidin 3-glucoside-isobutylcatechin, malvidin 3-glucoside-benzylcatechin, and malvidin 3-glucoside-3-methylbutylcatechin was respectively observed from each aldehyde. The structural characterization of these new structures has been elucidated by 1D and 2D NMR, mass spectrometry, and UV-vis techniques. These new adducts showed the same lambda(max) in the visible region at 540 nm, which is bathochromically shifted 15 nm when compared with the original anthocyanin (lambda(max) = 525 nm).

Aldehydes↗

PubMed2000

Application of response surface methodology to the study of methyl glucoside polyester synthesis parameters in a solvent-free system.

Response surface methodology (RSM) and 3-level-3-factor fractional factorial design were used to evaluate the effects of synthesis parameters, including reaction time (4 to 8 h), temperature (110 to 130 degrees C), and substrate molar ratio of fatty acid methyl esters (FAME) from soybean oil to methyl glucoside (4:1 to 6:1) on the percent molar conversion to methyl glucoside polyester (MGPE), utilizing 15 g of methyl glucoside as the reactant in a solvent-free system. All synthesis variables (reaction time, temperature, and substrate molar ratio) exhibited significant effects on percent molar conversion to MPGE in the experimental range. Optimization of the synthesis reaction was suggested by ridge max analysis to compute the estimated ridge of optimum response for increasing radii from the center of the original design. Based on the ridge max analysis, optimum conditions were: reaction time 6.3 h, synthesis temperature 123.8 degrees C, and substrate molar ratio 5.9:1. The predicted molar conversion was 55.68% (i.e., 15 g methyl glucoside yielded 56.5 g MGPE) at the optimum point.

Glucosides↗

PubMed2004

Ethyl glucoside in human urine following dietary exposure: detection by 1H NMR spectroscopy as a result of metabonomic screening of humans.

Metabonomic screening of human urine samples using 1H NMR spectroscopy has revealed the presence of signals resulting from the excretion of ethyl glucoside. Experiments in volunteers have demonstrated that this ethyl glucoside results from dietary exposure to the compound, which is present in beverages such as rice wine and sake, rather than representing a new route for the metabolism of ethanol by humans. The limited studies undertaken in volunteers indicate that ethyl glucoside has a longer biological half life than ethanol itself. The potential problems associated with using this glucoside metabolite as a marker of ethanol consumption are considered.

Chromatography, High Pressure Liquid↗

PubMed2007

Normal human plasma anti-beta-glucoside antibody has markedly elevated IgA content and binds fungal and yeast polysaccharides.

Normal human plasma antibody that recognizes beta-linked glucoside moiety was purified by affinity chromatography on cellulose. The anti-beta-glucoside antibody had three times higher IgA to IgG ratio and substantially higher polymeric IgA content than total serum immunoglobulins. Cellobiose and other beta-glucosides were best inhibitors of its binding to polystyrene microwell-coated polysaccharides. In synthetic glycoproteins made by conjugating disaccharides to hemoglobin or bovine serum albumin, cellobiose, unlike lactose or maltose, was sugar-specifically recognized by the antibody. It also recognized polystyrene well-coated beta1-->3 linked glycans of Saccharomyces cerevisiae, Candida albicans and of barley in decreasing order of affinity. Its sugar-binding site could thus accommodate beta-glucoside with or without substitution at C4 and C3. High IgA content along with the capacity to bind common microbial and dietary antigens pointed to the immune inflammatory potential of the antibody.

Antibodies↗

PubMed1996

Human melanoma and Chinese hamster ovary cells galactosylate n-alkyl-beta-glucosides using UDP gal:GlcNAc beta 1,4 galactosyltransferase.

We previously showed that human melanoma, CHO and other cells can convert beta-xylosides into structural analogs of ganglioside GM3. We have investigated several potential acceptors including a series of n-alkyl-beta-D-glucosides (n = 6-9). All were labeled with 3H-galactose when incubated with human melanoma cells. Octyl-beta-D-glucoside (Glc beta Octyl) was the best acceptor, whereas neither octyl-alpha-D-glucoside nor N-octanoyl-methylglucamine (MEGA 8) were labeled. Analysis of the products by a combination of chromatographic methods and specific enzyme digestions showed that the acceptors first received a single Gal beta 1,4 residue followed by an alpha 2,3 linked sialic acid. Synthesis of these products did not affect cell viability, adherence, protein biosynthesis, or incorporation of radiolabeled precursors into glycoprotein, glycolipid or proteoglycans. To determine which beta 1,4 galactosyl transferase synthesized Gal beta 1,4Glc beta Octyl, we analyzed similar incubations using CHO cells and a mutant CHO line (CHO 761) which lacks GAG-core specific beta 1,4 galactosyltransferase. The mutant cells showed the same level of incorporation as the control, eliminating this enzyme as a candidate. Thermal inactivation kinetics using melanoma cell microsomes and rat liver Golgi to galactosylate Glc beta Octyl showed the same half-life as UDP-Gal:GlcNAc beta 1,4 galactosyltransferase, whereas LacCer synthase was inactivated at a much faster rate. We show that Glc beta Octyl is a substrate for purified bovine milk UDP-Gal:GlcNAc beta 1,4 galactosyltransferase. Furthermore, the galactosylation of Glc beta Octyl by CHO cell microsomes can be competitively inhibited by GlcNAc or GlcNAc beta MU. These results indicate that UDP-Gal:GlcNAc beta 1,4 galactosyltransferase is the enzyme used for the synthesis of the alkyl lactosides when cells or rat liver Golgi are incubated with alkyl beta glucosides.

Animals↗

PubMed1989

The fate of dietary pyridoxine-beta-glucoside in the lactating rat.

[3H]5'-O-(beta-D-glucopyranosyl) pyridoxine (PN-glucoside) and [14C]pyridoxine (PN) were orally administered to lactating rats. Milk was collected from the dam, and the stomach contents and liver were collected from the suckling pups 24 and 48 h after administration. Analysis of the isotopic ratio (3H/14C) in the milk and stomach contents indicated that the secretion of 3H in the milk was 20-25% as great as the secretion of 14C. The only labeled form of 3H and 14C in the stomach contents was pyridoxal phosphate (PLP), indicating that PN-glucoside was hydrolyzed to PN and subsequently metabolized prior to secretion by the mammary gland. The isotopic ratio in the livers of the pups was similar to that of the stomach contents. Furthermore, the relative distribution of the two isotopes among the hepatic metabolites of the pups was similar. The results of this study indicate that intact PN-glucoside is not secreted in milk, although vitamin B-6 derived from the limited hydrolysis and metabolism of PN-glucoside is delivered to the mammary gland for secretion.

Animals↗

PubMed2001

Comparison of the intestinal absorption of quercetin, phloretin and their glucosides in rats.

Absorption and metabolism of quercetin and isoquercitrin (quercetin 3-O-glucose) were investigated in rats after in situ perfusion of jejunum plus ileum (15 nmol/min) for 30 min and compared with those of phloretin and phloridzin (phloretin 2'-O-glucose). After perfusion of the glucosides, the corresponding aglycone forms and conjugated derivatives appeared in the lumen. The conjugated metabolites were similar to those recovered after intestinal perfusion of the aglycone forms. Regardless of the aglycone or glucoside perfused, only conjugated forms were present in the mesenteric vein blood draining the perfused segment showing the importance of intestinal conjugation. The hydrolysis of glucosides was a prerequisite step before their conjugation by intestinal enzymes and their transport towards the mucosal and serosal sides. In contrast to phloridzin, lactase phloridzin hydrolase activity did not seem to be an essential pathway for isoquercitrin hydrolysis. The 3-O-glucosylation of quercetin improved the net absorption of the aglycone (P < 0.05), whereas phloretin absorption decreased when present as 2'-O-glucoside (P < 0.05). Whatever the perfused compound, the efficiency of the absorption seemed to be linked to the intestinal conjugation process and to the luminal secretion of metabolites.

Animals↗

PubMed2001

Kinetics of active alpha-glucoside transport in Saccharomyces cerevisiae.

alpha-Glucosides are the most abundant fermentable sugars in the industrial applications of Saccharomyces cerevisiae, and the active transport across the plasma membrane is the rate-limiting step for their metabolism. In this report we performed a detailed kinetic analysis of the active alpha-glucoside transport system(s) present in a wild-type strain, and in strains with defined alpha-glucoside permeases. Our results indicate that the wild-type strain harbors active transporters with high and low affinity for maltose and trehalose, and low-affinity transport systems for maltotriose and alpha-methylglucoside. The maltose permease encoded by the MAL21 gene showed a high affinity (K(m) approximately 5 mM) for maltose, and a low affinity (K(m) approximately 90 mM) for trehalose. On the other hand, the alpha-glucoside permease encoded by the AGT1 gene had a high affinity (K(m) approximately 7 mM) for trehalose, a low affinity (K(m) approximately 18 mM) for maltose and maltotriose, and a very low affinity (K(m) approximately 35 mM) for alpha-methylglucoside.

Biological Transport, Active↗