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At least 613 records · Page 34Linked to original sources
PubMed1984

Homogeneous enzyme immunoassay of diosgenin and its glycosides.

Homogeneous enzyme immunoassay has been used as a tool for the determination of diosgenin and its glycosides in plants. Diosgenin antisera was found to inhibit the activity of diosgenin hemisuccinate-horseradish peroxidase conjugate which was reversed by the addition of free diosgenin or its glycosides. The increase of enzyme activity was proportional to the quantity of the hapten over a certain range of hapten concentration. Thus, a minimum of 2.5 micrograms/ml of diosgenin and 11.5 micrograms/ml of diosgenin glycosides could be determined by this method. The results were comparable with those obtained by high-performance liquid chromatography and gravimetric methods.

Chromatography, High Pressure Liquid↗
PubMed1983

Protein-sugar interactions: environmental effect on the fluorescence of O-(4-methylumbelliferyl)-glycosides.

We have investigated the effect of 12 solvents and several amino acids on the fluorescence of O-(4-methylumbelliferyl)-glycosides. We showed that: i) the fluorescence quenching is not related to the dielectric constant of the solvents: the fluorescence intensity was maximal in water (d = 80) and in acetic acid (d = 6.2) and was at least ten times lower in acetone (d = 21) and in dioxane (d = 2.2); ii) the fluorescence of O-(4-methylumbelliferyl)-N-acetyl-beta-glucosaminide is not quenched in the presence of various amino acids including arginine, asparagine, aspartate, histidine, leucine, phenylalanine and proline; iii) the fluorescence of O-(4-methylumbelliferyl)-glycoside is quenched by sulfur, phenol and indole amino acids or derivatives containing sulfur, phenol or indole groups. The changes in fluorescence intensities of O-(4-methylumbelliferyl)-glycosides upon binding to concanavalin A, wheat germ agglutinin and lysozyme are discussed with regard to the amino acid content of their binding sites.

Amino Acids↗
PubMed1991

Conformational space of alpha 1-4 glycosidic linkage: a molecular dynamics study.

Molecular Dynamics simulations have been carried out for 100 ps on crystal structure of beta-cyclodextrin in vacuo and with explicit inclusion of solvent at constant pressure and constant temperature using the GROMOS MD algorithm, with a time step of 0.005 ps. The conformational space of the glycosidic linkage was studied by calculating two virtual dihedrals connecting the successive glucose units for the 2000 structures saved during the two simulations. Three preferred regions for alpha 1-4 glycosidic linkage were found in both the simulations. The use of these virtual dihedral angles in representing the glycosidic linkage is also brought out from these studies.

Algorithms↗
PubMed1988

Systematic chemical synthesis and n.m.r. spectra of methyl alpha-glycosides of isomalto-oligosaccharides and related compounds.

Acid-catalyzed thiophenolysis of 1,6-anhydro-2,3,4-tri-O-benzyl-beta-D-glucopyranose and acetylation of the resulting phenyl 2,3,4-tri-O-benzyl-1-thio-alpha-D-glucopyranoside (4) gave phenyl 6-O-acetyl-2,3,4-tri-O-benzyl-1-thio-alpha-D-glucopyranoside (5). Reaction of 5 with chlorine gave, stereospecifically, the corresponding beta-glycosyl chloride, which was treated with 4 in the presence of silver perchlorate and 2,4,6-trimethylpyridine to afford phenyl O-(6-O-acetyl-2,3,4-tri-O-benzyl-alpha-D-glucopyranosyl)-(1----6)-2,3,4- tri-O- benzyl-1-thio-alpha-D-glucopyranoside (17). Crystalline O-(6-O-acetyl-2,3,4-tri-O-benzyl-alpha-D-glucopyranosyl)-(1----6)-2,3,4- tri- O-benzyl-beta-D-glucopyranosyl chloride, readily obtainable in a stereo-specific manner from 17 by treatment with chlorine, was used as the key glycosyl (isomaltosyl) donor in the blockwise synthesis of methyl glycosides of isomalto-oligosaccharides, up to and including the octasaccharide. The methyl alpha-glycoside of isomaltotetraose fluorinated at C-6 of the terminal D-glucopyranosyl group was prepared by using SnCl2-activated 2,3,4-tri-O-benzyl-6-deoxy-6-fluoro-alpha,beta-D-glucopyranosyl fluoride as the glycosyl donor, a suitably protected methyl alpha-isomaltotrioside as the nucleophile, and silver perchlorate as the promoter. The n.m.r. spectra (1H- and 13C-) of numerous synthetic intermediates were analyzed and completely assigned by a variety of two-dimensional homo- and hetero-nuclear n.m.r.-spectroscopic techniques, and the final deprotected title oligosaccharides were characterized by 13C-n.m.r. data. Silver perchlorate-mediated glycosylation reactions involving beta-glycosyl chlorides were high-yielding and showed high stereo-selectivity for the formation of an alpha-(cis)-glycosidic linkage. The practical limitation of obtaining high isomalto-oligosaccharides in this way appears to lie solely in the separation technique applied for the resolution of the crude products formed.

Carbohydrate Conformation↗
PubMed1992

Synthesis and collagenase inhibition of new glycosides of aranciamycinone: the aglycon of the naturally occurring antibiotic aranciamycin.

Glycosides of aranciamycinone were prepared by glycosylation with sugar acetates and trimethylsilyl triflate in dichloromethane. Glycosides of the following sugars were prepared: alpha-L-rhamnopyranose, beta-D-glucopyranose, beta-D-ribopyranose, beta-D-xylopyranose, alpha-L-fucopyranose, 2-azido-2,6-dideoxy-alpha-L-mannopyranose, 2,6-dideoxy-alpha-L-arabino-hexopyranose, 3,6-dideoxy-alpha-L-arabino-hexopyranose, and 4,6-dideoxy-alpha-L-lyxo-hexopyranose. The new glycosides were tested for inhibition of Clostridium histolyticum collagenase and Yoshida Sarcoma tumor cells.

Animals↗
PubMed1992

Synthesis and properties of sulfated alkyl glycosides.

Alkyl glycosides were sulfated with sulfur trioxide-pyridine. Dodecyl alpha- and beta-D-glucopyranoside gave the corresponding 6-sulfates in 75 and 51% yields, respectively. Separation from polysulfated compounds was carried out by reversed-phase HPLC. Tetradecyl beta-maltopyranoside (16) gave a 88: 12 mixture of 6'- and 6-sulfates. The sulfated compounds were characterized by 1H-, 13C-, and 2-dimensional NMR spectroscopy. Surfactant and thermotropic liquid-crystalline properties of the sugar derivatives were examined. All of the glycosides show smectic phases (SA), and the clearing points rise by introduction of sulfate groups. Even glycosides having no unprotected hydroxy groups may show SA-phases when bearing sulfate groups. The mesomorphic properties cannot be explained by formation of distinct aggregates, but rather must be interpreted by an effective intramolecular contrast.

Alkylation↗
PubMed1993

(13C)-substituted sucrose: 13C-1H and 13C-13C spin coupling constants to assess furanose ring and glycosidic bond conformations in aqueous solution.

Sucrose (beta-D-fructofuranosyl alpha-D-glucopyranoside, 1), methyl alpha-D-fructofuranoside (2), and methyl beta-D-fructofuranoside (3) have been prepared by chemical and/or enzymic methods with single sites of 13C-substitution at C-1, C-2, C-3, and C-6 of the fructofuranosyl ring. 1H (500 MHz) and 13C (75 and 125 MHz) NMR spectra of 1-3 have been obtained, yielding 1H-1H, 13C-1H, and 13C-13C spin coupling constants that were used to assess furanose ring and glycoside bond conformations in aqueous (2H2O) solution. Results show that the conformational mobility of the furanosyl ring in 3 is altered when incorporated into 1. Furthermore, 13C-13C and 13C-1H spin couplings across the glycosidic linkage suggest a psi torsion angle different from that observed in the crystal (phi appears similar). Interplay between the strength of the exoanomeric effect and hydrogen bonding in solution may be responsible, in part, for the apparent conformational flexibility of 1. In addition, spin couplings in 2 and 3 have been compared to those measured previously in alpha-D-threo-pentulofuranose (4) and beta-D-threo-pentulofuranose (5), respectively, as a means to study the effect of glycosidation and hydroxymethyl substitution on the solution conformation of the 2-ketofuranose ring. The conversion of 4 to 2 is accompanied by minimal conformational change, whereas a significant change accompanies the conversion of 5 to 3, showing that the effect of substitution on ring conformation depends highly on ring configuration before and after substitution.

Carbohydrate Conformation↗
PubMed1996

FTIR and laser-Raman spectra of oligosaccharides in water: characterization of the glycosidic bond.

Changes in conformation of oligosaccharides, and the constraints imposed by hydrogen bonding with the solvent, were studied by means of vibrational spectroscopy (FTIR-ATR and laser-Raman). Oligosaccharides differing in positions of the glycosidic bond, such as trehalose, sucrose, maltose, melibiose, lactose, maltotriose, raffinose, and stachyose, were investigated. FTIR spectra of oligosaccharides in aqueous solution at different concentrations allow differentiation of these molecules according to the types of glycosidic bonds present and the changes in conformation of their constituent monosaccharides. Characteristic spectral ranges influenced by the glycosidic linkage position, overall hydration, and concentration of the aqueous solution were found. Tentative assignment of the observed IR and Raman bands was achieved.

Carbohydrate Sequence↗
PubMed1996

Synthesis of eight glycosides of hexasaccharide fragments representing the terminus of the O-polysaccharide of Vibrio cholerae O:1, serotype Inaba and Ogawa, bearing aglycons suitable for linking to proteins.

The title substances were prepared from intermediate, fully acetylated alpha-trimethylsilylethyl (SE) glycosides. The latter were assembled in a blockwise manner, using as the glycosyl donor the alpha-glycosyl chloride of a disaccharide bearing two 4-azido-4-deoxy functions. Next, the azido groups in the assembled hexasaccharides were converted to the corresponding amines, and these were acylated with 4-O-benzyl-3-deoxy-L-glycero-tetronic acid in the presence of a water-soluble carbodiimide. The SE glycosides were then transformed to glycosyl imidates, and these were coupled with methyl 6-hydroxyhexanoate or methyl 2-(2-hydroxyethylthio) propionate. The aglycons in the glycosides thus obtained were then converted to the corresponding carboxylic acids or acyl hydrazides. Such compounds are suitable for linking to proteins to obtain neoglycoproteins.

Carbohydrate Sequence↗
PubMed1975

Urinary excretion of free hydroxylysine, peptide-bound hydroxylysine and hydroxylysyl glycosides in physiological conditions.

The amount of urinary hydroxylysine is an index of collagen metabolism. Of the total hydroxylysine measured in normal urine 80 percent is associated with sugars in two glycosidic compounds, glucosyl-galactosyl-hydroxylysine and galactosyl-hydroxylysine, ten percent is free and unglycosylated and the remainder is bound to urinary peptides. The excretion of hydroxylysyl glycosides follow the same physiological variations as urinary hydroxyproline, but it is not influenced by a collagen-free diet. The urinary excretion of hydroxylysyl glycosides, free hydroxylysine and peptide-bound hydroxylysine increases from 6 months of age to puberty. When corrected for urinary creatinine excretion, the largest amounts are found before one year of age. The glucosyl-galactosyl-hydroxylysine/galactosyl-hydroxylysine ratio is lower in the urine of children. After correction of the values to either the body surface area or to the creatinine excretion, no significant differences can be found between the sexes. The different forms of hydroxylysine are discussed.

Adolescent↗
PubMed1985

Suppression of positive inotropic and toxic effects of cardiac glycosides by amiloride.

Effects of amiloride on the inotropic and toxic actions of cardiac glycosides were examined using left atrial muscle isolated from guinea pig heart. Preincubation of atrial muscle with amiloride significantly decreased the maximum positive inotropic effect of dihydrodigoxin but failed to reduce that of isoproterenol. Amiloride prevented the contracture and significantly reduced the incidence of arrhythmias induced by 2 microM digoxin. Similar experiments examining 5 microM digoxin-induced arrhythmias showed that amiloride increased both the time required to produce arrhythmias and the fractional occupancy of sarcolemmal Na,K-ATPase by digoxin at the onset of arrhythmias. The antagonism of cardiac glycoside actions was best observed during the decline in developed tension elicited by amiloride subsequent to its initial positive inotropic effect. Amiloride had no effect on binding site concentration for ATP-dependent [3H]ouabain binding but decreased affinity of the binding sites for ouabain in membrane preparations obtained from guinea pig heart. Furthermore, amiloride inhibited Na,K-ATPase activity and increased the IC50 value for ouabain inhibition of the enzyme. These results indicate that amiloride antagonizes the positive inotropic and toxic effects of cardiac glycosides. Possible mechanisms for the antagonism include inhibition of sarcolemmal Na+/Ca2+ or Na+/H+ exchange.

Amiloride↗
PubMed1984

Sugar moiety of cardiac glycosides is essential for the inhibitory action on the palytoxin-induced K+ release from red blood cells.

Palytoxin (PTX), a highly toxic and sugar-containing substance isolated from Palythoa tuberculosa, caused K+ release from rabbit red blood cells. Cardiac glycosides, such as ouabain, convallatoxin, cymarin, digoxin and digitoxin, inhibited the PTX-induced K+ release. Their corresponding aglycones did not inhibit the K+ release, but antagonized the inhibitory effect of the glycosides. All these cardiotonic steroids equally inhibited the activity of (Na+ + K+)-ATPase prepared from hog cerebral cortex. These results suggest that the sugar moiety of the cardiac glycosides is important for the inhibitory effect on the K+ release induced by PTX and that the inhibition is not related to their inhibitory potency on the (Na+ + K+)-ATPase activity.

Acrylamides↗
PubMed1989

Cardiac glycoside toxicity in small laboratory animals.

Cardiac glycosides are frequently administered to laboratory animals for research purposes. The effects achieved depend not only upon the particular glycoside and dose administered, but also upon an entire array of variables from the species of animal to the temperature of the animal housing facility. We review a number of these factors and their influence upon the effects achieved by the administration of cardiac glycosides to laboratory animals.

Age Factors↗
PubMed1990

Scammonins I and II, the resin glycosides of radix scammoniae from Convolvulus scammonia.

The ether-soluble resin glycoside ('jalapin') fraction obtained from scammony roots, on alkaline hydrolysis, gave a glycosidic acid, scammonic acid A, together with isobutyric, 2S-methylbutyric and tiglic acids. In addition, two kinds of resin glycosides, named scammonin I and II, were isolated and characterized, respectively, as (11S)-hydroxyhexadecanoic acid, 11-[( O-6-deoxy-4-O-(2(E)-methyl-1-oxo-2- butenyl)-beta-D-glucopyranosyl-(1----4)-O-6-deoxy-2-O-(2-methyl-1-oxobut yl)- alpha-L-mannopyranosyl-(1----2)-O-beta-D-glucopyranosyl-(1----2)-6-deoxy -beta- D-glucopyranosyl]oxy)-, intramol. 1,3"'-ester and (11S)-hydroxyhexadecanoic acid, 11-[( O-beta-D-glucopyranosyl-(1----4)-O-6-deoxy-2-O-(2-methyl-1-oxobutyl)- alpha-L-mannopyranosyl-(1----2)-O-beta-D-glucopyranosyl-(1----2)-6-deoxy -beta-D - glucopyranosyl]oxy)-, intramol. 1,3"'-ester.

Carbohydrate Sequence↗
PubMed1993

Triterpenoid glycosides from Stauntonia hexaphylla.

On the basis of spectroscopic and chemical methods, the structures of two new bisdesmosidic triterpenoid glycosides, named staunoside D and E, which were isolated from Stauntonia hexaphylla, were established as 3-O-(beta-D-glucopyranosyl(1-->2)-[beta-D- glucopyranosyl(1-->3)]-beta-D-glucopyranosyl)-hederagenin-28- O-[beta-D-glucopyranosyl (1-->6)-beta-D-glucopyranosyl] ester and 28-O-[alpha-L-rhamnopyranosyl (1-->4)-beta-D-glucopyranosyl(1-->6)-beta-D-glucopyranosyl]ester, respectively. Three known triterpenoid glycosides were also isolated. A new proglycoside was isolated from the cleavage of the ester-glycosidic linkage and its structure characterized.

Carbohydrate Sequence↗
PubMed1992

Phenylethanoid and lignan glycosides from Verbascum thapsus.

Verbascum thapsus afforded, in addition to three known phenylethanoid glycosides and four lignan ones, five new phenylethanoid glycosides and one new lignan glycoside. Structures of the compounds were elucidated by spectroscopic methods and chemical evidence.

Carbohydrate Sequence↗
PubMed1993

Structure-activity relationships of synthetic methyl ursolate glycosides.

From 15 synthetic methyl ursolate glycosides, the di- and tri-glycosides showed much higher haemolytic activity than the monoglycosides. The beta-gentiobioside and the beta-maltotrioside exhibited much stronger antibacterial (Staphylococcus aureus) or antifungal (Trichophyton mentagrophytes) activity than the other glycosides. However, none of them exhibited antibacterial activity against Bacillus subtilis.

Bacteria↗
PubMed1993

Steroid glycosides from Polygonatum prattii.

Investigation of the roots of Polygonatum prattii afforded three new steroid glycosides, paratiosides A-C, and three new prosapogenins, pratiosides D1, E1 and F1. The latter three, which were obtained from the enzymatic hydrolysis products of a glycoside mixture, are considered to be the corresponding spirostanol glycosides of their proto-type furostanol ones in the plant. The structures of these compounds were established by chemical and spectral methods. It is noted that pratioside C possessing a 3,27-di-O-sugar chain is the first example to be isolated from a natural source.

Carbohydrate Sequence↗