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PubMed1998

Subsolubilizing alterations caused by alkyl glucosides in phosphatidylcholine liposomes.

The subsolubilizing alterations caused by a series of alkyl glucosides (alkyl chain lengths ranging from C8 to C12) in unilamellar phosphatidylcholine (PC) liposomes were investigated. The surfactant to phospholipid molar ratios (RE) and the normalized bilayer/aqueous phase partition coefficients (K) were determined by monitoring the increase of the fluorescence intensity of liposome suspensions due to the 5(6)-carboxyfluorescein (CF) released from the interior of vesicles to the bulk aqueous phase. Given that the free surfactant concentrations was always lower than the critical micelle concentration (CMC) of the surfactant tested we may assume that the surfactant-liposome interactions were mainly ruled by the action of surfactant monomers. In general terms, the decrease in the surfactant alkyl chain length (or the rise in the surfactant CMC) resulted in an increase in the ability of these surfactants to alter the permeability of liposomes and, inversely, in an abrupt decrease in their affinity with these bilayers structures. The overall balance of these opposite tendencies shows that at the two interaction levels studied (50 and 100% of CF release) the nonyl and the octyl glucoside showed, respectively, the highest ability to alter the release of the CF trapped in bilayers (lowest RE values), whereas the dodecyl glucoside showed the highest degree of partitioning into liposomes or affinity with these bilayer structures (highest K values).

Glucosides↗

PubMed1996

Resistance of glucose-6-phosphate dehydrogenase deficiency to malaria: effects of fava bean hydroxypyrimidine glucosides on Plasmodium falciparum growth in culture and on the phagocytosis of infected cells.

The balanced polymorphism of glucose-6-phosphate dehydrogenase deficiency (G6PD-) is believed to have evolved through the selective pressure of malarial combined with consumption of fava beans. The implicated fava bean constituents are the hydroxypyrimidine glucosides vicine and convicine, which upon hydrolysis of their beta-O-glucosidic bond, became protein pro-oxidants. In this work we show that the glucosides inhibit the growth of Plasmodium falciparum, increase the hexose-monophosphate shunt activity and the phagocytosis of malaria-infected erythrocytes. These activities are exacerbated in the presence of beta-glucosidase, implicating their pro-oxidant aglycones in the toxic effect, and are more pronounced in infected G6PD- erythrocytes. These results suggest that G6PD- infected erythrocytes are more susceptible to phagocytic cells, and that fava bean pro-oxidants are more efficiently suppressing parasite propagation in G6PD- erythrocytes, either by directly affecting parasite growth, or by means of enhanced phagocytic elimination of infected cells. The present findings could account for the relative resistance of G6PD- bearers to falciparum malaria, and establish a link between dietary habits and malaria in the selection of the G6PD- genotype.

Animals↗

PubMed1988

Micelle-vesicle transition of egg phosphatidylcholine and octyl glucoside.

The dissolution and formation of egg phosphatidylcholine (PC) vesicles by the detergent octyl glucoside were examined systematically by using resonance energy transfer between fluorescent lipid probes, turbidity, and gel filtration chromatography. Resonance energy transfer was exquisitely sensitive to the intermolecular distance when the lipids were in the lamellar phase and to the transitions leading to mixed micelles. Turbidity measurements provided information about the aggregation of lipid and detergent. Several reversible discrete transitions between states of the PC-octyl glucoside system were observed by both methods during dissolution and vesicle formation. These states could be described as a series of equilibrium structures that took the forms of vesicles, open lamellar sheets, and mixed micelles. As detergent was added to an aqueous suspension of vesicles, the octyl glucoside partitioned into the vesicles with a partition coefficient of 63. This was accompanied by leakage of small molecules and vesicle swelling until the mole fraction of detergent in the vesicles was just under 50% (detergent:lipid ratio of 1:1). Near this point, a transition was observed by an increase in turbidity and release of large molecules like inulin, consistent with the opening of vesicles. Both a turbidity maximum and a sharp increase in fluorescence were observed at a detergent to lipid mole ratio of 2.1:1. This was interpreted as the lower boundary of a region where both lamellar sheets and micelles are at equilibrium. At a detergent:lipid ratio of 3.0:1, another sharp change in resonance energy transfer and clarification of the suspension were observed, demarcating the upper boundary of this two-phase region. This latter transition is commonly referred to as solubilization.(ABSTRACT TRUNCATED AT 250 WORDS)

Fluorescent Dyes↗

PubMed1988

Mechanisms of membrane protein insertion into liposomes during reconstitution procedures involving the use of detergents. 1. Solubilization of large unilamellar liposomes (prepared by reverse-phase evaporation) by triton X-100, octyl glucoside, and sodium cholate.

The mechanisms governing the solubilization by Triton X-100, octyl glucoside, and sodium cholate of large unilamellar liposomes prepared by reverse-phase evaporation were investigated. The solubilization process is described by the three-stage model previously proposed for these detergents [Lichtenberg, D., Robson, R.J., & Dennis, E.A.(1983) Biochim. Biophys. Acta 737, 285-304]. In stage I, detergent monomers are incorporated into the phospholipid bilayers until they saturate the liposomes. At that point, i.e., stage II, mixed phospholipid-detergent micelles begin to form. By stage III, the lamellar to micellar transition is complete and all the phospholipids are present as mixed micelles. The turbidity of liposome preparations was systematically measured as a function of the amount of detergent added for a wide range of phospholipid concentrations (from 0.25 to 20 mM phospholipid). The results allowed a quantitative determination of RSat, the effective detergent to lipid molar ratios in the saturated liposomes, which were 0.64, 1.3, and 0.30 for Triton X-100, octyl glucoside, and sodium cholate, respectively. The corresponding ratios in the mixed micelles, RSol, were 2.5, 3.8, and 0.9 mol of detergent/mol of phospholipid. The monomer concentrations of the three detergents in the aqueous phase were also determined at the lamellar to micellar transitions (0.18, 17, and 2.8 mM, respectively). These transitions were also investigated by 31P NMR spectroscopy, and complete agreement was found with turbidity measurements. Freeze-fracture electron microscopy and permeability studies in the sublytic range of detergent concentrations indicated that during stage I of solubilization detergent partitioning between the aqueous phase and the lipid bilayer greatly affects the basic permeability of the liposomes without significantly changing the morphology of the preparations. A rough approximation of the partition coefficients was derived from the turbidity and permeability data (K = 3.5, 0.09, and 0.11 mM-1 for Triton X-100, octyl glucoside, and sodium cholate, respectively). It is concluded that when performed systematically, turbidity measurements constitute a very convenient and powerful technique for the quantitative study of the liposome solubilization process by detergents.

Bacteriorhodopsins↗

PubMed1988

Composition of octyl glucoside-phosphatidylcholine mixed micelles.

The composition of mixed micelles of egg phosphatidylcholine (PC) and octyl glucoside was studied by a novel technique based on measuring resonance energy-transfer efficiency between two fluorescent lipid probes present in trace amounts. Equations were derived for calculating the stoichiometry of the composition of mixed micelles from the energy-transfer measurements. These were applied to determining the average number of lipid molecules in the octyl glucoside-egg PC mixed micelle as a function of detergent concentration. The average number of detergent molecules in these mixed micelles was independent of lipid concentration in the range studied (0-500 microM). The dependence of mixed micelle stoichiometry on the concentration of aqueous (monomeric) octyl glucoside is consistent with the assumptions of ideal mixing of the two amphiphiles in the mixed micelles and that mixed micelles can be treated as a distinct phase.

Energy Transfer↗

PubMed1989

Temperature dependence of the vesicle-micelle transition of egg phosphatidylcholine and octyl glucoside.

The temperature dependence of octyl glucoside micellization was determined and compared to the phase behavior of the octyl glucoside--egg phosphatidylcholine (PC) mixed system in excess water to help elucidate the process of vesicle formation from mixed surfactant-phospholipid micelles. The critical micelle concentration of octyl glucoside (OG) was determined from the sharp increase of ANS fluorescence at micellization in an NaCl buffer at temperatures ranging from 5 to 40 degrees C. The cmc decreased with increasing temperature from 31 mM at 5 degrees C to 16 mM at 40 degrees C. A similar but less steep temperature dependence is observed for the solubilization of egg PC vesicles by OG as monitored by the surfactant-dependent changes in (1) solution turbidity and (2) the resonance energy transfer between NBD-PE and Rho-PE incorporated in the vesicles. These assays identify two breakpoints, most likely the boundaries of the cylindrical micelle and spheroidal micelle coexistence region. The [OG]aq values at these two breakpoints have similar temperature dependencies. However, the cylindrical mixed micelles at the boundary have nearly identical OG:PC ratios over the temperature range studied, whereas the spheroidal mixed micelles have relatively more OG at the higher temperatures (OG:PC ratio increases from 2.92 to 3.72 between 5 and 35 degrees C). Estimation of the acyl volume to surface area ratio for the compositions observed suggests that this parameter remains constant over temperature. The spheroidal mixed micelles, but not the cylindrical PC-OG micelles, exhibit ideal mixing between the two components at all temperatures (5-35 degrees C). This temperature sensitivity may be utilized to improve the efficacy of membrane protein reconstitution.(ABSTRACT TRUNCATED AT 250 WORDS)

Colloids↗

PubMed2004

Adsorption of flavonoids on resins: cyanidin 3-glucoside.

Adsorption of cyanidin-3-glucoside in aqueous batch solutions was studied at pH 3.5 and 20 degrees C using 13 commercial resins with different hydrophobicity, surface areas (SA, 330-1200 m2/g), and pore radii (PR, 20-260 A). The solute affinity toward different resins was described in terms of Langmuir and Freundlich parameters; experimental data were well-fitted to the two isotherms, which were both utilized to compare resins adsorption capacity. The styrene-divinylbenzene EXA-118 resin (SA, 1200 m2/g; PR, 90 A) showed the maximum effectiveness among the tested resins; a good efficacy for removing cyanidin 3-glucoside was shown also by EXA-90 (SA, 630 m2/g; PR, 105 A). Some experiments on a styrene-divinylbenzene resin and an acrylic one demonstrated that adsorption was not influenced by pH variations of the solution within the range of 1.0-4.5. For the 10 resins having PR < or = 105 A, correlation analysis evidenced the linear increasing dependence of Freundlich constant KF on physical characteristics of surface area and pore radius. The adsorption of cyanidin 3-glucoside at 20 degrees C was compared with that of hesperidin performed in batch runs on the same resins. Moreover, the best resin (EXA-118) was tested with a sample of pigmented orange juice to assess its performance in terms of selectivity, adsorption, and desorption capabilities on a real matrix.

Adsorption↗

PubMed2005

Inhibiting effects of resveratrol and its glucoside piceid against Venturia inaequalis, the causal agent of apple scab.

Resveratrol is a phytoalexin produced in different unrelated plant species such as grapevine and peanut. The effect of resveratrol and its glucoside trans-resveratrol-3-O-beta-D-glycopyranosid (piceid) against Venturia inaequalis, the causal agent of apple scab, was evaluated using a newly established test based on enzymatically isolated cuticular membranes (CMs) from apple (Malus domestica Borkh.) leaves. The test substances resveratrol and piceid were either sorbed to CMs before inoculation with spores or were applied simultaneously with the Venturia inaequalis spores to the CMs, and their effect on germination, appressoria formation, and penetration was examined. Resveratrol had no influence on spore germination but a significant inhibiting effect on penetration when applied simultaneously as well as before. A percentage inhibition of 89.7 +/- 11.5 and 61.8 +/- 35.1 was observed for simultaneous and preapplication, respectively. The resveratrol glucoside piceid had a significant inhibitory effect on germination and completely inhibited penetration of the fungus at concentrations between 200 and 400 microg mL(-1) when applied simultaneously with the spores to the CMs. On piceid-enriched CM (preapplication), spores germinated but penetration was inhibited nearly completely (96.1 +/- 5.1%). Thus, in vitro experiments showed that resveratrol and its glucoside in fact could contribute to improving the pathogen resistance of apple leaves.

Ascomycota↗

PubMed2006

Purification and structure determination of glucosides of capsaicin and dihydrocapsaicin from various Capsicum fruits.

Two new glucosides, capsaicin-beta-D-glucopyranoside (1) and dihydrocapsaicin-beta-D-glucopyranoside (2), were discovered in the fruit of the Capsicum annuum cultivar 'High Heat'. They were sequentially purified by acetone extraction, n-hexane extraction, and acetonitrile extraction, followed by medium-pressure liquid chromatography and high-performance liquid chromatography performed on an octadecylsilane column. Their chemical structures were elucidated by proton nuclear magnetic resonance, carbon nuclear magnetic resonance, and hydrolysis with alpha- and beta-glucosidases. The glucosides were also detected in various pungent cultivars of C. annuum, Capsicum frutescens, and Capsicum chinense by liquid chromatography-mass spectrometry. However, they were not detected in nonpungent cultivars of C. annuum. Furthermore, a positive correlation was observed between the quantity of the capsaicinoids, capsaicin, and dihydrocapsaicin and their glucosides.

Capsaicin↗

PubMed2006

Evaluation of the antioxidant capacity of limonin, nomilin, and limonin glucoside.

The antioxidant capacity (AOC) of three representative citrus limonoids, limonin, nomilin, and limonin glucoside, was examined by the oxygen radical absorbance capacity (ORAC), Trolox equivalent antioxidant capacity (TEAC), beta-carotene-linoleic acid bleaching, and 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging assays. Pure compounds and proper negative (cinnamic acid) and positive (2,6-di-tert-butyl-4-methylphenol (BHT) and ascorbic acid) controls were used to remove any ambiguity in interpreting results. In all cases, limonin and nomilin gave results equivalent to those of cinnamic acid, indicating that they do not possess any inherent AOC and should not be considered antioxidants. Similar results were observed for limonin glucoside, with the exception of an anomalous result obtained from the beta-carotene-linoleic acid bleaching assay. Limonin glucoside was deemed not to be an antioxidant on the basis of the three unequivocal assays.

Antioxidants↗

PubMed1999

Conversion of citronellyl diphosphate and citronellyl beta-D-glucoside into rose oxide by Pelargonium graveolens.

Deuterium-labeled citronellyl diphosphate and citronellyl beta-D-glucoside were fed to Pelargonium graveolens. Both precursors were converted into cis-/trans-rose oxide. Citronellyl diphosphate is more effectively converted into rose oxide. The phloem exudate of P. graveolens was analyzed after enzymatic cleavage of the glucosidated and phosphorylated volatiles. It could be shown that glucosidically bound citronellol is translocated in the plant. Phosphorylated citronellol could not be detected.

Deuterium↗

PubMed2000

Isolation of novel glucosides related to gingerdiol from ginger and their antioxidative activities.

Two novel glucosides of 6-gingerdiol were isolated from fresh ginger (Zingiber officinale Roscoe). Their structures were determined as 1-(4-O-beta-D-glucopyranosyl-3-methoxyphenyl)-3,5-dihydroxydecane (1) and 5-O-beta-D-glucopyranosyl-3-hydroxy-1-(4-hydroxy-3-methoxyphenyl)deca ne (2) by HRFAB-MS and NMR analyses, and the absolute configurations of both aglycons were identified as (3S,5S) by a comparison with synthetic compounds. After incubating these glucosides with acetone powder prepared from fresh ginger, they were confirmed to have been hydrolyzed to 6-gingerdiol by HPLC. This result suggests that these glucosides are the precursors or intermediates of 6-gingerdiol. To recognize their function, their antioxidative activities were investigated and compared to that of their aglycon, 6-gingerdiol, by a linoleic acid model system and by their DPPH radical-scavenging ability. Although 1 did not indicate any activity, 2 had as strong activity as the aglycon in both measurements.

Acetone↗

PubMed1976

Studies in the design of x-ray contrast agents. Synthesis, hydrophobicity, and solubility of some iodoresorcyl bis(beta-glucosides).

Two diiodo- and two triiodoresorcyl bis(beta-glucosides) were prepared and their hydrophobicity (log P octano) and water solubility were compared to a triiodophenyl beta-glucoside and several experimental nonionic, water-soluble, x-ray contrast agents. The data indicate steric overlap of the halogen substituents by the bulky hydrophilic O-beta-glucosyl substituents; high water solubility is attained only at observed log P octanol approximately 1.5 or lower. Of the new compounds, only 2,4,-6-triiodo-5-N-methylcarboxamidorescorcy bis(beta-glucoside) (6) was highly water soluble. At the physiological pHin dog's plasmia in vitro, compound 6 rapidly hydrolyzed. Poorly water-soluble but more stable compounds of this series were not appreciably absorbed from dog's duodenum.

Animals↗

PubMed1990

Stereochemical characterization of the diastereomers of the amobarbital N-glucosides excreted in human urine.

The stereochemistry associated with the amobarbital N-glucoside diastereomers (1a and 1b) that are excreted by humans in urine is unknown. Using X-ray crystallography, the absolute configuration of 1b was determined to be S (C-5 position of the barbiturate ring). Following oral administration of amobarbital to Caucasians and Orientals, from 5 to 25% of the dose of amobarbital was excreted in the urine as 1b. The other diastereomer, 1a, accounted for less than 0.1 to 0.2% of the dose in four individuals, with none detected in nine individuals. The rate constants, kf,1b, determined from the urinary excretion of 1b were lower than those previously reported for unresolved amobarbital N-glucosides. However, based on the urinary excretion of 1b, the rate constants, K, for elimination of amobarbital in Caucasians and Orientals were similar to those previously determined from the serum levels of amobarbital and the urinary excretion of unresolved amobarbital N-glucosides. In previous studies of the N-glucosylation of amobarbital, it is likely that a single N-glucose diastereomer, 1b, was being observed.

Adult↗

PubMed2004

Luteolin and luteolin-7-O-glucoside from dandelion flower suppress iNOS and COX-2 in RAW264.7 cells.

Both reactive oxygen- and nitrogen-derived reactive species play important roles in physiological and pathophysiological conditions. Flavones, luteolin and luteolin-7-O-glucoside along with a rich plant source of both flavones, namely dandelion (Taraxacum officinale) flower extract were studied for antioxidant activity in different in vitro model systems. In this current study, luteolin and luteolin-7-O-glucoside at concentrations lower than 20 microM, significantly (p < 0.05) suppressed the productions of nitric oxide and prostaglandin E2 (PGE2) in bacterial lipopolysaccharide activated-mouse macrophage RAW264.7 cells without introducing cytotoxicity. The inhibitory effects were further attributed to the suppression of both inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein expression, and not reduced enzymatic activity. Similar suppression for both inducible enzymes was also found with the presence of dandelion flower extract, specifically, the ethyl acetate fraction of dandelion flower extract which contained 10% luteolin and luteolin-7-O-glucoside.

Animals↗

PubMed2002

Functional expression of human liver cytosolic beta-glucosidase in Pichia pastoris. Insights into its role in the metabolism of dietary glucosides.

Human tissues such as liver, small intestine, spleen and kidney contain a cytosolic beta-glucosidase (CBG) that hydrolyses various beta-d-glycosides, but whose physiological function is not known. Here, we describe the first heterologous expression of human CBG, a system that facilitated a detailed assessment of the enzyme specificity towards dietary glycosides. A full-length CBG cDNA (cbg-1) was cloned from a human liver cDNA library and expressed in the methylotrophic yeast Pichia pastoris at a secretion yield of approximately 10 mg x L-1. The recombinant CBG (reCBG) was purified from the supernatant using a single chromatography step and was shown to be similar to the native enzyme isolated from human liver in terms of physical properties and specific activity towards 4-nitrophenyl-beta-D-glucoside. Furthermore, the reCBG displayed a broad specificity with respect to the glycone moiety of various aryl-glycosides (beta-D-fucosides, alpha-L-arabinosides, beta-D-glucosides, beta-D-galactosides, beta-L-xylosides, beta-D-arabinosides), similar to the native enzyme. For the first time, we show that the human enzyme has significant activity towards many common dietary xenobiotics including glycosides of phytoestrogens, flavonoids, simple phenolics and cyanogens with higher apparent affinities (K(m)) and specificities (k(cat)/K(m)) for dietary xenobiotics than for other aryl-glycosides. These data indicate that human CBG hydrolyses a broad range of dietary glucosides and may play a critical role in xenobiotic metabolism.

Amino Acid Sequence↗

PubMed1987

Cell division promoting activity of naturally occurring dehydrodiconiferyl glucosides: do cell wall components control cell division?

Naturally occurring isomers of the dehydrodiconiferyl glucosides have been isolated from Vinca rosea crown gall tumors and have been tested for cell division promoting activities in the tobacco pith and leaf assay systems. The enantiomeric isomers A and B are active, although they are required at concentrations up to 2 orders of magnitude higher than zeatin riboside to promote comparable growth. We estimate that the active dehydrodiconiferyl glucosides are present in rapidly growing tissues (tumor tissue, habituated tissue, cultured nontransformed tissue) in micromolar concentrations. In quiescent tobacco pith tissue, the levels of these compounds are reduced by a factor of 100. These results suggest that cytokinin may exert control of cell division through the accumulation of molecules (the dehydrodiconiferyl glucosides) that are apparent cell wall components.

Cell Division↗

PubMed1990

Octyl glucoside extracts GTP-binding regulatory proteins from rat brain "synaptoneurosomes" as large, polydisperse structures devoid of beta gamma complexes and sensitive to disaggregation by guanine nucleotides.

GTP-binding regulatory proteins are generally purified from cholate-extracted membranes in the form of heterotrimers (G proteins) consisting of a GTP-binding subunit (alpha protein) complexed with a tightly interacted heterodimer termed beta gamma. In this study we extracted the proteins from rat brain "synaptoneurosomes" using the neutral detergent 1-octyl beta-D-glucopyranoside (octyl glucoside). Using specific antibodies for detection by immunoblotting and sucrose gradients for analyzing hydrodynamic properties, we found that each species of alpha protein (alpha subunits of stimulatory, inhibitory, and brain GTP-binding proteins) exhibited a broad range (4 S to greater than 12 S) of polydisperse structures with peak values (5 S to 7 S) considerably greater than that of heterotrimeric G proteins. The beta subunit proteins, for example, appeared as a homogeneous peak at 4.4 S within which only a fraction of the total alpha proteins can be associated. Incubation of octyl glucose extracts at 30 degrees C rapidly sedimented the alpha proteins but not the beta proteins. Incubation at 30 degrees C with guanosine 5'[gamma-thio]triphosphate (10-100 microM) prevented rapid sedimentation. Hydrodynamic analysis revealed that all alpha proteins were converted to approximately 4 S structures by the actions of guanosine 5'-[gamma-thio]triphosphate without change in the hydrodynamic properties of the beta proteins. Extraction of the membranes with sodium cholate instead of octyl glucoside resulted in complete loss of the large, polydisperse structures of the alpha proteins; the S values were approximately 4 S, in the range for beta proteins. These findings suggest that the transducing GTP-binding proteins in synaptoneurosomes exist as polydisperse, possibly multimer, structures of various size that are stable in octyl glucoside but destroyed by cholate. The polydisperse structures are not associated with beta gamma complexes and are sensitive to the disaggregating effects of guanosine 5'-[gamma-thio]triphosphate.

Animals↗