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At least 865 records · Page 48Linked to original sources
PubMed2005

Leishmanicidal cycloartane-type triterpene glycosides from Astragalus oleifolius.

Two new cycloartane-type glycosides oleifoliosides A (1) and B (2) were isolated from the lower stem parts of Astragalus oleifolius. Their structures were identified as 3-O-[beta-xylopyranosyl-(1 --> 2)-alpha-arabinopyranosyl]-6-O-beta-xylopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxycycloartane and 3-O-[beta-xylopyranosyl-(1 --> 2)-alpha-arabinopyranosyl]-6-O-beta-glucopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxycycloartane, respectively, by means of spectroscopic methods (IR, 1D and 2D NMR, ESI-MS). Three known cycloartane glycosides cyclocanthoside E (3), astragaloside II (4) and astragaloside IV (5) were also isolated and characterized. All five compounds were evaluated for in vitro trypanocidal, leishmanicidal and antiplasmodial activities as well as their cytotoxic potential on primary mammalian (L6) cells. Except for the compound 5, all compounds showed notable growth inhibitory activity against Leishmania donovani with IC50 values ranging from 13.2 to 21.3 microg/ml. Only weak activity against Trypanosoma brucei rhodesiense was observed with the known compounds astragaloside II (4, IC50 66.6 microg/ml) and cyclocanthoside E (3, IC50 85.2 microg/ml), while all compounds were inactive against Trypanosoma cruzi and Plasmodium falciparum. None of the compounds were toxic to mammalian cells (IC50's > 90 microg/ml). This is the first report of leishmanicidal and trypanocidal activity of cycloartane-type triterpene glycosides.

Animals↗
PubMed1992

Binding studies on internal immunodeterminants: synthesis of beta-(1----6)-linked oligosaccharide methyl glycosides having one to four internal D-galactopyranosyl residues flanked by gentiobiose residues.

The oligosaccharide glycosides beta-D-Glcp-(1----6)-beta-D-Glcp-(1----6)-[beta-D-Galp-(1----6)]n-beta-D - Glcp-(1----6)-beta-D-Glcp-1----OMe (n = 1-4) were prepared by a convergent block synthesis. Haloacetyl, tert-butyldiphenylsilyl, and dimethylthexylsilyl groups were used as temporary protective groups for the preparation of the intermediate glycosyl donors and acceptors. The deoxygenated trisaccharide glycosides beta-D-Glcp-(1----6)-beta-D-Galp-(1----6)-4-deoxy-beta-D-xylo-Hexp -1----OMe and beta-D-Glcp-(1----6)-4-deoxy-beta-D-xylo-Hexp-(1----6)-beta-D-Galp -1----OMe were also synthesized. The binding of each glycoside to the monoclonal antigalactan antibody IgA J539 was studied and the results support the previous finding that J539 can bind to internal antigenic epitopes. The data are consistent with the interpretation that subsite C of that antibody binds glucose with a Ka of approximately 6 (cf. 10.9 for galactose).

Antibodies, Monoclonal↗
PubMed2000

Chalcone and flavonol glycosides from Asarum canadense (Aristolochiaceae).

Two chalcone glycosides were isolated, together with seven known flavonol glycosides, from the leaves of Asarum canadense. The structures of the chalcone glycosides were established as chalcononaringenin 2',4'-di-O-glucoside and chalcononaringenin 2'-O-glucoside-4'-O-gentiobioside by chemical, UV, FAB MS, 1H and 13C NMR evidence.

Flavonoids↗
PubMed2000

Flavonoid glycosides and saponins from Astragalus shikokianus.

A new flavonol glycoside, kaempferol 3-O-alpha-L-rhamnopyranosyl -(1-->6)-[alpha-L-rhamnopyranosyl-(1-->2)]-beta-D-galactopyranosyl-7-O-a lpha-L-rhamnopyranoside, named astrasikokioside I, was isolated from aerial part of Astragalus shikokianus, together with two flavonol glycosides, kaempferol 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-galactopyranosyl-7-O-alpha-L- rhamnopyranoside, robinin, and three triterpenoid glycosides, soyasaponin I, sophoraflavoside II and robinioside E.

Chromatography, Thin Layer↗
PubMed2006

Bioavailability of genistein and its glycoside genistin as measured in the portal vein of freely moving unanesthetized rats.

The present study describes an in vivo bioavailability experiment for genistein and its glycoside genistin, either as pure compounds or from a soy protein isolate extract, using freely moving unanesthetized rats with a cannulation in the portal vein. The results show that genistein is readily bioavailable, being observed in portal vein plasma at the first point of detection at 15 min after dosing. The AUC(0-24h) values for total genistein and its conjugates were 54, 24, and 13 microM h for genistein, genistin, and an enriched protein soy extract, respectively. These results indicate that the bioavailability of genistein is higher for the aglycon than for its glycoside. Genistin is partly absorbed in its glycosidic form. It is concluded that bioavailability studies based on portal vein plasma levels contribute to insight into the role of the intestine and liver in deglycosylation and uptake characteristics of glycosylated flavonoids.

Animals↗
PubMed2002

Synthesis of the Salmonella type E(1) core trisaccharide as a probe for the generality of 1-(benzenesulfinyl)piperidine/triflic anhydride combination for glycosidic bond formation from thioglycosides.

A synthesis of a chromogenic glycoside of the Salmonella anatum group E(1) core trisaccharide is presented in which all three glycosidic bonds, a 1,2-cis-equatorial, a 1,2-trans-axial, and a 1,2-trans-equatorial linkage representing three of the four main classes of glycosidic bond, are formed with thioglycoside donors activated under a single set of conditions by the combination of 1-(benzenesulfinyl)piperidine and trifluoromethanesulfonic anhydride. 2,3-O-Carbonyl- and 2,3-O-isopropylidene-alpha-L-rhamnopyranosyl thioglycosides are found to be highly alpha-selective rhamnosyl donors under these conditions.

Chemistry, Organic↗
PubMed1996

Thermodynamics of alpha-Cyclodextrin-p-Nitrophenyl Glycoside Complexes. A Simple System To Understand the Energetics of Carbohydrate Interactions in Water.

Thermodynamic studies of the binding of a series of p-nitrophenyl glycosides (PNPGly) of varying stereochemistry to alpha-cyclodextrin (alpha-CD) were performed at three different temperatures (25, 35, and 42 degrees C) using a microcalorimetric technique. The system p-nitrophenol (PNP) at pH = 3 and alpha-CD was also studied for the sake of comparison. All these complexes were found to be enthalpy driven with a favorable enthalpic term clearly dominant over an unfavorable entropic term. A clear enthalpy-entropy compensation effect was observed at all the temperatures, with a slope close to unity (alpha = 1.02) and an intercept TDeltaS degrees (o) = 2.91 kcal mol(-)(1). This thermodynamic pattern is in agreement with those usually found for lectin-carbohydrate associations and for the binding processes of several host-guest systems. This pattern is explained in terms of the contribution of primarily two driving forces: the van der Waals interactions between the host and the guest, and the solvation/desolvation processes which accompany the association reaction. The presence of the carbohydrate molecule in the PNP ring causes a slight destabilization of the complex at 25 degrees C with respect to the alpha-CD-PNP (pH = 3) complex, although a different behavior has been observed depending on the axial/equatorial configuration of the glycoside and the temperature. This behavior is modulated by the stereochemistry of the glycoside. Differences were observed between the deoxy-derivatives (LAra and LFuc) and those derivatives with a hydroxymethyl group (Glc, Gal, Man). DeltaC(p) degrees values were obtained from the dependency of DeltaH degrees on temperature (=( partial differentialDeltaH degrees / partial differentialT)(p)). These values are small and negative except for alphaMan complex. For the latter complex, discrepancy between the calorimetric and the calculated van't Hoff enthalpies was observed. Parallels are drawn between the thermodynamics of our model and those proposed for carbohydrate-protein associations.

Journal Article↗
PubMed1997

The Calyculaglycosides: Dilophol-Type Diterpene Glycosides Exhibiting Antiinflammatory Activity from the Caribbean Gorgonian Eunicea sp.(1)(,)(2).

Three new diterpenoid hexose-glycosides, calyculaglycosides A-C (1-3) were isolated from the Caribbean gorgonian Eunicea sp. Calyculaglycosides A-C are rare diterpene glycosides possessing dilophol (4) aglycones related in biosynthetic origin to the elemene-type glycoside class of potent antiinflammatory agents known as fuscosides. The structures of the new compounds, which were assigned on the basis of spectral studies, were further corroborated by molecular modeling studies. Calyculaglycoside B (2) is an effective topical antiinflammatory agent stronger in potency than the industrial standard indomethacin. Calyculaglycoside B inhibits the synthesis of both prostaglandin PGE(2) and leukotriene LTB(4), suggesting it is a nonselective inhibitor of the 5-lipoxygenase and cyclooxygenase pathways. At concentrations of 10(-4)-10(-5)M, calyculaglycoside B produced LC(50)-level differential responses against a majority of the NCI ovarian cancer lines and several of the renal, prostate, and colon tumor lines.

Journal Article↗
PubMed2001

Two new cytotoxic and virucidal trisulfated triterpene glycosides from the Antarctic sea cucumber Staurocucumis liouvillei.

Two new trisulfated triterpene glycosides, liouvillosides A (1) and B (2), have been isolated from the Antarctic sea cucumber Staurocucumis liouvillei. Their structures have been elucidated by spectroscopic analysis (NMR and FABMS) and chemical transformations. Liouvillosides A (1) and B (2) are two new examples of a small number of trisulfated triterpene glycosides from sea cucumbers belonging to the family Cucumariidae. Both glycosides were found to be virucidal against herpes simplex virus type 1 (HSV-1) at concentrations below 10 microg/mL.

Animals↗
PubMed2005

Holothurins B(2), B(3), and B(4), new triterpene glycosides from mediterranean sea cucumbers of the genus holothuria.

Triterpene glycosides of three species of the Mediterranean sea cucumbers Holothuria polii, Holothuria tubulosa, and Holothuria sp. were studied. Three new monosulfated biosides, holothurins B(2) (1), B(3) (2), and B(4) (3), along with the previously known holothurins A (4) and B (5) were isolated from the sea cucumber H. polii. Triterpene glycosides belonging to holothurin A and B groups were found in H. tubulosa, while only one individual glycoside, holothurin A (4), was isolated from Holothuria sp. Structures of new substances were elucidated on the basis of spectral data (2D NMR and MS). The significance of holothurins as chemotaxonomic markers of the animals belonging to the genus Holothuria and taxonomic status of some representatives of the holothurians studied are discussed.

Animals↗
PubMed1999

Three novel C-glycosidic ellagitannins, rhoipteleanins H, I, and J, from rhoiptelea chiliantha

Three novel C-glycosidic ellagitannins named rhoipteleanins H (1), I (2), and J (3) were isolated from the fruits and bark of Rhoiptelea chiliantha Diels et Hand.-Mazz. (Rhoipteleaceae), and the structures were elucidated on the basis of detailed spectroscopic analysis and chemical evidence. Rhoipteleanin H possesses a unique cyclopentenone carboxyl moiety, which is probably formed by oxidation and subsequent rearrangement of an aromatic ring of a usual C-glycosidic ellagitannin. Rhoipteleanin I is the first ellagitannin having a hydroxynaphthalene glucoside moiety. Rhoipteleanin J is a dimeric ellagitannin generated by dehydrative coupling between two molecules of a monomeric C-glycosidic ellagitannin and subsequent oxidation of an aromatic ring. From a chemotaxonomic viewpoint, presence of these characteristic ellagitannins in this plant provides a further support for the establishment of the order Rhoipteleales comprising Rhoipteleaceae as the only family.

Journal Article↗
PubMed2003

Stimulation of mouse resistance to bacterial infection with muramyl dipeptide glycoside.

We studied the capacity of 9 new muramyl dipeptide glycosides to stimulate mouse resistance to experimental sepsis induced by intraperitoneal injection of salmonella typhimurium culture. Preventive intraperitoneal injections of muramyl dipeptide beta-glycosides better improved survival of infected animals compared to the original (unmodified) muramyl dipeptide and muramyl dipeptide alpha-glycosides. The most effective drug muramyl dipeptide beta-heptylglycoside injected during sepsis development also reduced animal mortality, decreased bacterial contamination of the viscera, and increased phagocytic activity of peritoneal macrophages in infected animals.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1965

The flavonol glycosides in the fruit of Pyrus communis L. cultivar Bon Chrétien.

1. Two new flavonol glycosides were isolated from the fruit of Pyrus communis L. cultivar Bon Chrétien. These were identified as isorhamnetin 3-rhamnogalactoside and a derivative of isorhamnetin 3-glucoside which was associated (possibly acylated) with an unknown aliphatic organic acid. 2. The melting point of isorhamnetin 3-glucoside isolated from Bon Chrétien pears is different from that of isorhamnetin 3-glucoside previously isolated from Argemone mexicana and Calendula officinalis. 3. Isorhamnetin 3-rhamnoglucoside was isolated from the fruit of Pyrus communis L. cultivar Bon Chrétien. This glycoside appears to be identical with narcissin, previously isolated from Narcissus tazetta and Lilium auratum. 4. Isoquercitrin, previously reported to be present in pear leaves, was isolated from the fruit of Bon Chrétien pears. 5. The isolated glycosides were present in the peels and flesh of the fruit, but were absent from the cores.

Journal Article↗
PubMed1999

Gas-liquid chromatography of the heptafluorobutyrate derivatives of the O-methyl-glycosides on capillary columns: a method for the quantitative determination of the monosaccharide composition of glycoproteins and glycolipids.

We have developed a method involving the formation of hepta-fluorobutyrate derivatives of O-methyl-glycosides liberated from glycoproteins and glycolipids following methanolysis. The stable derivatives of the most common monosaccharides of these glycoconjugates (Ara, Rha, Xyl, Fuc, Gal, Man, Glc, GlcNAc, GalNAc, Neu5Ac, KDN) can be separated and quantitatively and reproducibly determined with a high degree of sensitivity level (down to 25 pmol) in the presence of lysine as an internal standard. The GlcNAc residue bound to Asn in N-glycans is quantitatively recovered as two peaks. The latter were easily distinguished from the other GlcNAc residues of N-glycans, thus allowing a considerable improvement of the data on structure of N-glycans obtained from a single carbohydrate analysis. The most common contaminants present in buffers commonly used for the isolation of soluble or membrane-bound glycoproteins (SDS, Triton X-100, DOC, TRIS, glycine, and polyacrylamide or salts, as well as monosaccharide constituents of proteoglycans or degradation products of nucleic acids) do not interfere with these determinations. A carbohydrate analysis of glycoproteins isolated from a SDS/PAGE gel or from PDVF membranes can be performed on microgram amounts without significant interferences. Since fatty acid methyl esters and sphingosine derivatives are separated from the monosaccharide peaks, the complete composition of gangliosides can be achieved in a single step starting from less than 1 microg of the initial compound purified by preparative Silicagel TLC. Using electron impact ionization mass spectrometry, reporter ions for the different classes of O-methyl-glycosides (pentoses, deoxy-hexoses, hexoses, hexosamines, uronic acids, sialic acid, and KDN) allow the identification of these compounds in very complex mixtures. The mass of each compound can be determined in the chemical ionization mode and detection of positive or negative ions. This method presents a considerable improvement compared to those using TMS derivatives. Indeed the heptafluorobutyrate derivatives are stable, and acylation of amino groups is complete. Moreover, there is no interference with contaminants and the separation between fatty acid methyl-esters and O-methyl glycosides is achieved.

Acylation↗
PubMed1991

Characterization by 1H NMR of glycosidic conformations in the tetramolecular complex formed by d(GGTTTTTGG).

We have conducted two dimensional NOESY studies on the molecule d(G2T5G2) to characterize the structure of the tetramolecular complex previously identified by calorimetric and spectroscopic studies (1). Analysis of the NOE and exchange cross peaks observed in the NOESY spectra establishes the formation of structured conformations at low temperature (5 degrees C). Significantly, within each strand of these structured conformations, the G1 and G8 residues adopt syn glycosidic torsion angles, while the G2 and G9 residues adopt anti glycosidic torsion angles. Consequently, any structure proposed for the tetramolecular complex of d(G2T5G2) must have alternating G(syn) and G(anti) glycosidic torsion angles within each strand. The implications of this observation for potential structures of the tetramolecular complex of d(G2T5G2) are discussed.

Base Sequence↗
PubMed2007

GlycoMapsDB: a database of the accessible conformational space of glycosidic linkages.

Conformational energy maps of the glycosidic linkages are a valuable resource to gain information about preferred conformations and flexibility of carbohydrates. Here we present GlycoMapsDB, a new database containing more than 2500 calculated conformational maps for a variety of di- to pentasaccharide fragments contained in N- and O-glycans. Oligosaccharides representing branchpoints of N-glycans are included in the set of fragments, thus the influence of neighbouring residues is reflected in the conformational maps. During refinement of new crystal structures, maps contained in GlycoMapsDB can serve as a valuable resource to check whether the torsion values of a glycosidic linkage are located in an 'allowed' region similar to the Ramachandran plot analysis for proteins. This might help to improve the structural quality of the glycan data contained in the Protein Data Bank (PDB). A link between GlycoMapsDB and the PDB has been established so that the glycosidic torsions of all glycans contained in the PDB can be retrieved and compared to calculated data. The service is available at www.glycosciences.de/modeling/glycomapsdb/.

Carbohydrate Conformation↗
PubMed1998

X-ray structure of human lysozyme labelled with 2',3'-epoxypropyl beta-glycoside of man-beta1,4-GlcNAc. Structural change and recognition specificity at subsite B.

Human lysozyme (HL) labelled with the 2',3'-epoxypropyl beta-glycoside of Man-beta1,4-GlcNAc was crystallized at pH 4.5. The cell dimensions were a = 36.39, b = 116.38, c = 30.91 A and the space group was P212121. The unit cell contained four molecules (Vm = 2.18 A3 Da-1). The crystal structure was determined by molecular replacement and refined to an R value of 0.168 for 7060 reflections [|Fo| > 3sigma(F)] in the resolution range 8.0-2.1 A. A prominent shift of the Calpha-atom positions by up to 3.8 A in the region of residues 45-50 was observed compared with wild-type HL. Owing to the conformational change in this region the intermolecular contacts were altered remarkably compared to wild-type HL, explaining the difference in molecular packing. The Man-beta1,4-GlcNAc moiety occupied subsites B and C in the substrate-binding site of HL. Several differences in the hydrogen-bonded contacts between the ligand part and the protein part were observed for HL labelled with the 2',3'-epoxypropyl beta-glycoside of Man-beta1,4-GlcNAc compared with HL labelled with the corresponding derivatives of GlcNAc-beta1, 4-GlcNAc and Gal-beta1,4-GlcNAc. In contrast to the replacement of GlcNAc with Gal, the replacement of GlcNAc with Man did not sacrifice the stacking interactions with the side-chain group of Tyr63 as determined by the parallelism of the apolar face of the carbohydrate residue and the aromatic plane of the Tyr63 side chain. The 2',3'-epoxypropyl beta-glycoside of Man-beta1,4-GlcNAc exhibited almost the same affinity towards HL as Gal-beta1,4-GlcNAc, a much lower affinity than that of GlcNAc-beta1,4-GlcNAc. The difference in the protein-ligand interactions was discussed in relation to the carbo-hydrate-residue recognition specificity at subsite B of HL. The results suggested that Gln104 was a determinant for the strong recognition of GlcNAc residue at subsite B in HL.

Affinity Labels↗
PubMedDate not supplied

Structure of N-glycosidic carbohydrates of secretory proteins of Tetrahymena thermophila.

Glycoproteins secreted by Tetrahymena into the culture medium were isolated and the N-glycosidic oligosaccharides analyzed using lectin blots and fluorophore-assisted carbohydrate gel electrophoresis (FACE). Lectin blots showed that the glycoproteins secreted by Tetrahymena contain only N-glycosidic structures of the high mannose type. Further analysis using the FACE technology revealed the presence of four different N-glycosidic structures differing only in the number of mannose residues attached to the core chitobiose unit.

Animals↗