Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “GLYCOSIDES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,549 records · Page 86Linked to original sources
PubMed2003

S-Benzoxazolyl (SBox) glycosides as novel, versatile glycosyl donors for stereoselective 1,2-cis glycosylation.

[reaction: see text] Novel glycosyl donors, S-benzoxazolyl (SBox) glycosides, have been synthesized, tested toward various protecting group manipulations, and applied to the highly stereoselective 1,2-cis glycosylation. These compounds fulfill the requirements for a modern glycosyl donor such as accessibility, high stability toward protecting group manipulations, and mild activation conditions. It was also demonstrated that SBox glycosides withstand other glycosyl donor activation conditions and therefore allow selective glycosylations of O-pentenyl and thioglycosides.

Acrolein↗
PubMed2003

New stereoselective beta-C-glycosidation by uncatalyzed 1,4-addition of organolithium reagents to a glycal-derived vinyl oxirane.

[reaction: see text] Epoxide 4 is generated in situ from d-glucal-derived hydroxy mesylate 3. Reaction of epoxide 4 with a series of alkyl- and aryllithium reagents affords 2,3-unsaturated beta-C-glycosides with excellent 1,4-regioselectivity and complete stereoselectivity for the beta-glycoside. Other organometallic reagents demonstrate more complex behavior in their reactions with epoxide 4.

Ethylene Oxide↗
PubMed2002

Determination of the glycosidic torsion angles in uniformly 13C-labeled nucleic acids from vicinal coupling constants 3J(C2)/4-H1' and 3J(C6)/8-H1'.

A two-dimensional, quantitative J-correlation NMR experiment for precise measurements of the proton-carbon vicinal coupling constants 3J(C2)/4-H1' and 3J(C6)/8-H1' in uniformly 13C-labeled nucleic acids is presented. To reduce loss of signal due to 1H-13C dipole-dipole relaxation, a multiple-quantum constant time experiment with appropriately incorporated band selective 1H and 13C pulses was applied. The experiment is used to obtain the 3J(C2)/4-H1' and 3J(C6)/8-H1' coupling constants in a uniformly 13C, 15N-labeled [d(G4T4G4)]2 quadruplex. The measured values and glycosidic torsion angles in the G-quadruplex, obtained by restrained molecular dynamics with explicit solvent using the previously published restraints, along with selected data from the literature are used to check and modify existing parameters of the Karplus equations. The parameterizations obtained using glycosidic torsion angles derived from the original solution and recently determined X-ray structures are also compared.

Carbon Radioisotopes↗
PubMed1992

Correlation between the inhibitory effects of basic drugs on the uptake of cardiac glycosides and taurocholate by isolated rat hepatocytes.

The role of the multispecific bile acid transporter for cardiac glycoside uptake is still controversial. This study was designed to examine the inhibitory effects of basic drugs (verapamil, dipyridamole, nifedipine, chlorpromazine, disopyramide, quinidine, propranolol, and lidocaine) on taurocholate uptake by isolated rat hepatocytes and to compare these effects with inhibition of ouabain uptake. Sodium-dependent taurocholate uptake was significantly reduced, to 50-70% of the control value, by 50 microM verapamil, dipyridamole, and nifedipine. Sodium-independent taurocholate uptake was more extensively inhibited, to 20-40%, by these basic drugs. The inhibition of ouabain uptake correlated better with sodium-independent taurocholate uptake (gamma = 0.918) than with sodium-dependent taurocholate uptake (gamma = 0.714). Taurocholate competitively inhibited ouabain uptake in the absence of sodium. These results indicate that the cardiac glycoside transport system is similar to the sodium-independent taurocholate transport system.

Animals↗
PubMed2004

Patterns of iridoid glycoside production and induction in Plantago lanceolata and the importance of plant age.

Induction of allelochemicals is one way that plants efficiently deploy defenses against herbivory. In two separate experiments we investigated the time course of this inductive response and the importance of the timing of herbivory for Plantago lanceolata (Plantaginaceae). We found a localized induced response of catalpol and the ratio of catalpol to total iridoid glycosides in damaged leaves that was evident at d 6 after caterpillars of the specialist Junonia coenia were put onto the plants. On the whole plant level, we detected small, but significant changes in the iridoid glycoside metabolism of P. lanceolata on several different days following herbivory. We also found considerable change in the amounts of allelochemicals produced during P. lanceolata's ontogeny. This ontogenetic effect might help to explain some of the reasons why induction may be difficult to detect in P. lanceolata. We also investigated the importance of the timing of herbivory on P. lanceolata's inductive response, but neither herbivory after 5 wk of growth nor after 6 or 7 wk of growth induced an increase in aucubin or catalpol.

Glucosides↗
PubMed1980

The acid lability of the glycosidic bonds of L-iduronic acid residues in glycosaminoglycans.

Heparan sulphate, heparin and dermatan sulphate were hydrolysed in 0.5M-H2SO4 at 100 degrees C. At intervals portions of the hydrolysate were removed and treated with HNO2 at pH 4.0 to cleave the glycosidic bonds of the N-unsubstituted hexosamine residues and to convert both free and combined hexosamines into anhydrohexoses. These hydrolysis/deamination mixtures were reduced with NaB3H4 and analysed by radiochromatography for alpha-L-iduronosylanhydrohexose, beta-D-glucuronosylanhydrohexose, and the free uronic acids and anhydrohexose. These data gave a kinetic profile of the cleavage of the alpha-L-iduronosyl and the beta-D-glucuronosyl bonds in these glycosaminoglycans. The beta-D-glucuronosyl bonds showed the expected resistance to acid hydrolysis, but the alpha-L-iduronosyl bonds were found to be as labile to acid as some neutral sugar glycosides. This unusual lability of alpha-D-iduronosyl-anhydromannitol and beta-D-glucuronosylanhydromannitol. The procedures used to follow the kinetics of glycosaminoglycan hydrolysis can also be sued to obtain quantitative analyses of L-iduronic acid, D-glucuronic acid and hexosamine in these polymers.

Chemical Phenomena↗
PubMed1987

Plant glycosides in a liposomal drug-delivery system.

Plant glycosides were incorporated into the liposomal surface to study their sugar-specific uptake by various tissues. Two steroid glycosides, namely floribundasaponin D, with rhamnose as terminal sugar, and gracillin, with glucose and rhamnose as end sugars, were selected for the purpose. 125I-human IgG encapsulated liposomes composed of egg lecithin (phosphatidylcholine), cholesterol, dicetyl phosphate (optional) and either floribundasaponin D or gracillin, when injected into the tail vein of rat, showed significantly higher uptake in the rat liver than in appropriate controls. Whereas the uptake of floribundasaponin D liposomes was observed to be non-specific, the increased uptake of the gracillin liposomes, as judged from the inhibition studies with asppropriate sugars, was specific for glucose, although the receptor was unable to distinguish between the alpha and beta anomers ('anomerically blind'). The liver-perfusion studies showed that the uptake of gracillin liposomes was mostly by non-parenchymal cells.

Animals↗
PubMed1975

[Serum concentration of glycosides and digitalis intoxication(author's transl)].

Serum glycoside concentration was 2.3 ng/ml or more in 299 patients digitalised with digoxin or digoxin derivatives. Mean serum glycoside concentration was 3.4 +/- 1.3 ng/ml (range 2.3-11.00 ng per ml). Usually, high serum concentrations were associated with advanced den or digoxin-derivative overdosage occurred in only 10% of patients. Almost three quarters of those with intoxication had impaired renal function. There was some evidence that low body-weight increased the potential risk of intoxication.

Arrhythmias, Cardiac↗
PubMed2002

New lupane glycosides from Pulsatilla chinensis.

Two new lupane glycosides along with five known triterpenoids were isolated from the roots of Pulsatilla chinensis (Ranunculaceae). The structures of the new glycosides were determined to be 3-O-beta-D-glucopyranosyl(1-->3)-alpha-L-arabinopyranosyl-23-hydroxybetulinic acid 28-O-alpha-L-rhamnopyranosyl(1-->4)-beta-D-glucopyranosyl(1-->6)-beta-D-glucopyranosyl ester (pulsatilloside D, 6) and 3-O-[beta-D-glucopyranosyl(1-->4)][alpha-L-rhamnopyranosyl(1-->2)]-alpha-L-arabinopyranosyl-23-hydroxybetulinic acid 28-O-alpha-L-rhamnopyranosyl(1-->4)-beta-D-glucopyranosyl(1-->6)-beta-D-glucopyranosyl ester (pulsatilloside E, 7) by spectroscopic analysis and chemical methods. The compounds were evaluated for cytotoxic activities against K-562 human leukemia and HeLa cells.

Biological Assay↗
PubMed1991

Subalpinoside (S1), an Unknown Oleandrigenin Glycoside and Other Cardenol from Digitalis subalpina var. subalpina.

From the leaves of DIGITALIS SUBALPINA Br.-Bl. var. SUBALPINA an oleandrigenin glycoside was isolated as the main cardiotonic compound besides some known glycosides such as evatromonoside, lanatoside A and B, gitoroside, and others. The structure of this compound was elucidated by spectroscopic methods ( (1)H-, (13)C-, 2D-NMR spectroscopy) as gluco-oleandrigenin digitoxoside. This is the first report of the occurrence of oleandrigenin derivatives in a DIGITALIS species.

Journal Article↗
PubMed1990

[New Prenylflavonoid Glycosides from Epimedium koreanum].

Two new prenylflavonol glycosides epimedokoreanoside I ( 7) and epimedokoreanoside II ( 8) were isolated from EPIMEDIUM KOREANUM Nakai (Berberidaceae) beside five other known prenylflavonol glycosides with hypotensive activity. The structures were elucidated by spectroscopic and chemical methods.

English Abstract↗
PubMed2002

Heparin and heparan sulfate disaccharides bind to the exchanger inhibitor peptide region of Na+/Ca2+ exchanger and reduce the cytosolic calcium of smooth muscle cell lines. Requirement of C4-C5 unsaturation and 1--> 4 glycosidic linkage for activity.

Heparin and heparan sulfate fragments, obtained by bacterial heparinase and heparitinases, bearing an unsaturation at C4-C5 of the uronic acid moiety, are able to produce up to 80% reduction of the cytosolic calcium of smooth muscle cell lines. Unsaturated disaccharides from chondroitin sulfate, dermatan sulfate, and hyaluronic acid are inactive, indicating that, besides the unsaturation of the uronic acid, a vicinal 1 --> 4 glycosidic linkage is needed. An inverse correlation between the molecular weight and activity is observed. Thus, the ED(50) of the N-acetylated disaccharide derived from heparan sulfate (430 Da) is 88 microm compared with 250 microm of the trisulfated disaccharide (650 Da) derived from heparin. Except for enoxaparin (which contains an unsaturation at the non-reducing end and 1 --> 4 glycosidic linkage), other low molecular weight heparins and native heparin are practically inactive in reducing the cytosolic calcium levels. Thapsigargin (sarcoplasmic reticulum Ca(2+)-ATPase inhibitor), vanadate (cytoplasmic membrane Ca(2+)-ATPase inhibitor), and nifedipine and verapamil (Ca(2+) channel antagonists) do not interfere with the effect of the trisulfated disaccharide upon the decrease of the intracellular calcium. A significant decrease of the activity of the trisulfated disaccharide is observed by reducing extracellular sodium, suggesting that the fragments might act upon the Na(+)/Ca(2+) exchanger promoting the extrusion of Ca(2+). This was further substantiated by binding experiments and circular dichroism analysis with the exchanger inhibitor peptide.

Amino Acid Sequence↗
PubMed2003

Identification of the catalytic residues in family 52 glycoside hydrolase, a beta-xylosidase from Geobacillus stearothermophilus T-6.

beta-d-Xylosidases (EC 3.2.1.37) are exo-type glycoside hydrolases that hydrolyze short xylooligosaccharides to xylose units. The enzymatic hydrolysis of the glycosidic bond involves two carboxylic acid residues, and their identification, together with the stereochemistry of the reaction, provides crucial information on the catalytic mechanism. Two catalytic mutants of a beta-xylosidase from Geobacillus stearothermophilus T-6 were subjected to detailed kinetic analysis to verify their role in catalysis. The activity of the E335G mutant decreased approximately 106-fold, and this activity was enhanced 103-fold in the presence of external nucleophiles such as formate and azide, resulting in a xylosyl-azide product with an opposite anomeric configuration. These results are consistent with Glu335 as the nucleophile in this retaining enzyme. The D495G mutant was subjected to detailed kinetic analysis using substrates bearing different leaving groups (pKa). The mutant exhibited 103-fold reduction in activity, and the Brønsted plot of log(kcat) versus pKa revealed that deglycosylation is the rate-limiting step, indicating that this step was reduced by 103-fold. The rates of the glycosylation step, as reflected by the specificity constant (kcat/Km), were similar to those of the wild type enzyme for hydrolysis of substrates requiring little protonic assistance (low pKa) but decreased 102-fold for those that require strong acid catalysis (high pKa). Furthermore, the pH dependence profile of the mutant enzyme revealed that acid catalysis is absent. Finally, the presence of azide significantly enhanced the mutant activity accompanied with the generation of a xylosyl-azide product with retained anomeric configuration. These results are consistent with Asp495 acting as the acid-base in XynB2.

Amino Acid Substitution↗
PubMed2003

Bioactivity of secoiridoid glycosides from Centaurium erythraea.

As part of our on-going search for bioactive compounds from Scottish plants, two secoiridoid glycosides, swertiamarin and sweroside, have been isolated from the aerial parts of Centaurium erythraea Rafn (Family: Gentianaceae) by reversed-phase preparative HPLC coupled with a photo-diode-array detector. The structures of these compounds were elucidated unambiguously by UV, FABMS and extensive 1D and 2D NMR spectroscopic analyses and also by comparing experimental data with literature data. Antibacterial, free radical scavenging activities and general toxicity of these glycosides have been assessed. Both compounds inhibited the growth of Bacillus cereus, Bacillus subtilis, Citrobacter freundii and Escherichia coli. While swertiamarin was also active against Proteus mirabilis and Serratia marcescens, sweroside inhibited the growth of Staphylococcus epidermidis. Swertiamarin and sweroside exhibited significant general toxicity in brine shrimp lethality bioassay and the LD50 values were 8.0 microg/ml and 34 microg/ml, respectively, whereas that of the positive control podophyllotoxin, a well known cytotoxic lignan, was 2.79 microg/ml. Chemotaxonomic implications of these compounds in the family Gentianaceae have also been discussed briefly.

Animals↗
PubMed2002

Quinovic acid glycosides from Mitragyna stipulosa--first examples of natural inhibitors of snake venom phosphodiesterase I.

Phytochemical investigations on the non-alkaloidal extracts of Mitragyna stipulosa bark has led to the isolation of a series of triterpenoids mainly consisting of quinovic acid ([structure: see text]) and its glycoside derivatives [structure: see text] and [structure: see text]. The other constituents isolated include alpha-amyrin, 3beta-acetyl ursolic acid and a mixture of oleanolic and ursolic acid and beta-sitosterol glucopyranoside. Their structures were identified by spectral and chemical studies and compounds [structure: see text] and [structure: see text] were, respectively, identified as quinovic acid 3-O-[beta-D-glucopyranoside] (quinovin glycoside C) and quinovic acid 3-O-[beta-D-quinovopyranoside]-27-O-[beta-D-glucopyranosyl] ester. Compounds [structure: see text] and [structure: see text] showed significant inhibitory activity against snake venom phosphodiesterase I.

Cameroon↗
PubMed2003

Anti-oxidative activity of glycosides from Ligustrum sinense.

Three active glycosides that afford protection to red blood cell membrane to resist hemolysis induced by a peroxyl radical initiator, 2,2'-azo-bis-(2-amidinopropane) dihydrochloride (AAPH) were isolated from the MeOH extract of Ligustrum sinense. The compounds are 10-hydroxyl-oleuropein (1), 3-O-alpha-L-rhamnopyranosyl-kaempferol-7-O-beta-D-glucopyranoside (4), and 8'-alpha-hydroxyl-lariciresinol-4'-O-beta-D-glucopyranoside (6). The structures of these glycosides were determined by 1D and 2D NMR spectral analysis.

Amidines↗
PubMed2006

New phenolic glycosides from the stems and leaves of Casearia multinervosa.

Four phenolic glycosides (1-4), including two new ones (3 and 4), have been isolated from the stems of Casearia multinervosa and identified as arbutin (1), 4-O-E-caffeoylarbutin (2), 4-O-E-coumaroylarbutin (3) and 4-O-E-feruloylarbutin (4), respectively. In addition, the two known phenolic glycosides (1 and 2) were also isolated from the leaves. Structures were elucidated on the basis of spectroscopic evidence. Compounds 1-4 were tested for cytotoxicity against the P388 mouse lympholytic cell line by an ATP Lite-M assay method and showed mild to moderate activity.

Animals↗
PubMed1997

4-Methylumbelliferyl glycosides of N-acetyl 4-thiochito-oligosaccharides as fluorogenic substrates for chitodextrinase from Vibrio furnissii.

The degradation of chitin involves a diverse array of enzymes, some with overlapping substrate specificities. In order to distinguish between different types of enzymes, specific substrates are needed. Toward this end, two new fluorogenic substrates containing thio-glycosidic linkages, 4-methylumbelliferyl N,N'-diacetyl-4-thio-beta-chitobioside (Mu-TCB) and N,N',N"-triacetyl-4,4'-dithio-beta-chitotrioside (Mu-TCT) are described. The substitution of the glycosidic oxygens (except the one that links oligosaccharide with the fluorogenic aglycon) with a sulfur atom resulted in resistance of these compounds to N-acetyl-beta-hexosaminidases while they were specific substrates for the newly discovered chitodextrinase from Vibrio furnissii (Keyhani,N.O. and Roseman,S. (1996) J. Biol. Chem., 271, 33414-33424) and some bacterial chitinases. The enzyme kinetics of these 4-S-linked substrates, Mu-TCB and Mu-TCT, as well as the O-linked 4-methylumbelliferyl N,N'-diacetyl-beta-chitobioside (Mu-CB) and N,N',N"-triacetyl-beta-chitotrioside (Mu-CT) with the chitodextrinase were studied and compared. The usefulness of the substrates for screening for chitodextrinase and/or chitinase activity was demonstrated.

Carbohydrate Sequence↗