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At least 937 records · Page 52Linked to original sources
PubMed1988

Direct stereochemical assignment of sugar subunits in naturally occurring glycosides by low energy collision induced dissociation. Application to papulacandin antibiotics.

A tandem mass spectrometric method is described which allows the assignment of stereochemistry to fragment ions comprising intact sugar subunits of larger glycosides without chemical degradation and product isolation by chromatography. The approach relies on the mass selection of the 'sugar ion' of interest followed by analysis of stereoselective fragmentation induced by low-energy collisional activation. The daughter ion spectra provide configurational fingerprints of the selected sugar ions which can be matched for identity with reference spectra obtained from suitable precursors of known stereochemistry. Glucose, mannose and galactose furnished the required set of the most important reference ions. By using peracetyl (and perdeuterioacetyl) derivatives, galactose was readily identified as the glycosidic sugar constituent of the (known) antibiotic papulacandin B and a further (unknown) congener.

Aminoglycosides↗
PubMed1989

Mass spectrometric analysis of cardiac glycosides by the desorption/ionization technique potassium ion ionization of desorbed species.

The analysis of cardiac glycosides by the desorption/ionization (D/I) mass spectrometric technique potassium ion ionization of desorbed species (K+IDS) is presented. K+IDS mass spectra of digitonin, digoxin, digoxigenin, digitoxin and ouabain are discussed to demonstrate the capabilities of this D/I method. The K+IDS analysis consists of two steps: thermal desorption of neutral molecules representative of the analyte, followed by gas-phase addition of K+ ions to these species. Structural and molecular weight information of the cardiac glycosides is obtained with the K+IDS technique. The most intense peak in the K+IDS mass spectrum of an analyte, M, is frequently the [M]K+ ion. Interpretation of the K+IDS mass spectra is simple, since one thermal degradation mechanism dominates. This mechanism is a 1,2-elimination process. A variation of the original K+IDS technique, performed by changing the ionizing metal from K+ to Na+ (i.e. Na+IDS), is presented for the analysis of digoxin. The Na+IDS mass spectrum of digoxin contains more structural information than the K+IDS mass spectrum of that compound. This may lead to a means of controlling the types of information obtainable with this D/I technique by varying the cation that is thermionically generated. K+IDS analyses can be performed rapidly, no sample derivatization is necessary, no matrix is required and little instrument modification is necessary.

Cardiac Glycosides↗
PubMed2006

New antioxidant phenolic glycosides from Walsura yunnanensis.

Four new polyphenolic glycosides (1-4) were isolated from the BuOH extract of the bark of Walsura yunnanenis C. Y. Wu. These compounds comprise two lignans, i.e., the 9-O-alpha-L-arabinopyranosides 1 and 2 of (-)-isolariciresinol and of (+)-5-methoxyisolariciresinol, respectively, and the two phenolic glycosides 3,4,5-trimethoxyphenyl 2-O-(alpha-L-fucopyranosyl)-beta-D-glucopyranoside (3) and 3,5-dihydroxyphenyl 6-O-(4-hydroxy-3,5-dimethoxybenzoyl)-beta-D-glucopyranoside (walsuraside; 4). In addition, three known compounds, 3,4,5-trimethoxyphenyl beta-D-glucopyranoside, asperglaucide, and butyl alpha-D-fructofuranoside were identified. Their structures were elucidated spectroscopically and by chemical transformation (hydrolysis). The new compounds 1, 2, and 4 displayed significant antioxidant activities, with IC(50) values in the range of ca. 42 to 49 microg/ml.

Antioxidants↗
PubMed2006

Antitrypanosomal cycloartane glycosides from Astragalus baibutensis.

Baibutoside (5), a new cycloartane-type triterpene glycoside, has been isolated from the roots of Astragalus baibutensis along with four known glycosides, acetylastragaloside I (1), and astragalosides I, II, and IV (2-4, resp.). The structure elucidation of the compounds were achieved by a combination of one- and two-dimensional NMR techniques (DQF-COSY, HSQC, HMBC, and ROESY), and mass spectrometry (ESI-MS), where all the compounds were shown to have cycloastragenol (=(20R,24S)-3beta,6alpha,16beta,25-tetrahydroxy-20,24-epoxy-9,19-cyclolanostane) as aglycone. All compounds were tested for in vitro antiprotozoal activity. Compounds 1-4 displayed notable activity vs. Trypanosoma brucei rhodesiense, with acetylastragaloside I (1) being the most potent (IC50 9.5 microg/ml). Acetylastragaloside I (1) was also lethal to T. cruzi (IC50 5.0 microg/ml), and it is the first cycloartane-type triterpene with remarkable trypanocidal activity against both T. brucei rhodesiense and T. cruzi. However, it exhibits some cytotoxicity on mammalian cells.

Animals↗
PubMed2004

Analgesic, antiinflammatory and CNS depressant activities of sesquiterpenes and a flavonoid glycoside from Polygonum viscosum.

Analgesic, antiinflammatory and CNS depressant activities of four sesquiterpenes, viscosumic acid, viscozulenic acid, viscoazucine and viscoazulone, and a flavonoid glycoside, quercetin-3-O-(6''-feruloyl)-beta-D-galactopyranoside isolated form the aerial parts of Polygonum viscosum (Polygonaceae) have been assessed. All test compounds exhibited CNS depressant activity in open field test, all but viscoazulone showed analgesic activity in Eddy's hot plate test, all sesquiterpenes inhibited acetic acid induced abdominal writhing in mice, and all but viscoazucine and the flavonoid glycoside exhibited mild to moderate antiinflammatory effect on carrageenan induced rat paw edema.

Acetic Acid↗
PubMed2003

Chemical composition and antioxidant test of free and glycosidically bound volatile compounds of savory (Satureja montana L. subsp. montana) from Croatia.

The evaluation of antioxidant power of glycosidically bound volatile aglycones from savory shows that these compounds possess antioxidative activity comparable to that of the essential oil, but less effective compared to the well-known antioxidant butylated hydroxytoluene (BHT) and alpha-tocopherol. Thus, since the glycosides are able to release their aglycones by enzymatic hydrolysis, they could be considered as possible precursors of antioxidant substances in savory.

Antioxidants↗
PubMed2002

Direct stereochemical assignment of hexose and pentose residues in flavonoid O-glycosides by fast atom bombardment and electrospray ionization mass spectrometry.

Mass spectrometric methods have been developed which allow the direct stereochemical assignment of terminal monosaccharide residues in flavonoid O-glycosides without the need for chemical hydrolysis. Standards containing a glucose, galactose, mannose, xylose, arabinose or apiose residue were examined because these monosaccharides are by far the most commonly encountered in flavonoid glycosides. Following acetylation, the major peracetylated sugar related fragments, generated by fast atom bombardment (FAB) or electrospray ionization (ESI), were selected for collisional activation employing a broad range of collision energies. Both FAB and ESI proved to be useful as ionization techniques. Stereoselective fragmentation was achieved and allowed us clearly to differentiate and characterize isomeric monosaccharide residues. The method developed was successfully applied to an unknown flavonoid containing a terminal pentose and hexose residue which was isolated from Farsetia aegyptia.

Flavonoids↗
PubMed1983

Improvement of the oral bioavailability of digitalis glycosides by cyclodextrin complexation.

Inclusion complexes of the digitalis glycosides digitoxin, digoxin, and methyl digoxin with three cyclodextrins (alpha-, beta-, gamma-homologues) in water and in the solid state were studied by a solubility method, IR and 1H-NMR spectroscopy, and X-ray diffractometry. Solid complexes (in a molar ratio of 1:4) of the digitalis glycosides with gamma-cyclodextrin were prepared and their in vivo absorption examined. The rapidly dissolving form of the gamma-cyclodextrin complex significantly increased plasma levels of digoxin (approximately 5.4-fold) after oral administration to dogs.

Animals↗
PubMed2004

Complete assignments of 1H and 13C NMR data for 10 phenylethanoid glycosides.

Ten phenylethanoid glycosides, including two new ones, isolated from the aerial parts of the mangrove plant Acanthus ilicifolius were identified. The first complete assignments of the 1H and 13C NMR chemical shifts for these glycosides were achieved by means of 2D NMR techniques, including 1H-1H COSY, TOCSY, HSQC and HMBC spectra.

Acanthaceae↗
PubMedDate not supplied

Identification and quantification of galloyl derivatives, flavonoid glycosides and anthocyanins in leaves of Pistacia lentiscus L.

Separation, identification and quantification of polyphenols was carried out on leaves of Pistacia lentiscus L., an evergreen member of the family Anacardiaceae, using semi-preparative HPLC, HPLC-photodiode array detection and HPLC-MS analysis, together with 1H- and 13C NMR. Three major classes of secondary metabolites were detected: (i) gallic acid and galloyl derivatives of both glucose and quinic acid; (ii) flavonol glycosides, i.e. myricetin and quercetin glycosides; and (iii) anthocyanins, namely delphinidin 3-O-glucoside and cyanidin 3-O-glucoside. Low amounts of catechin were also detected. The concentration of galloyl derivatives was extremely high, representing 5.3% of the leaf dry weight, and appreciable amounts of myricetin derivatives were also detected (1.5% on a dry weight basis). These findings may be useful in establishing a relationship between the chemical composition of the leaf extract and the previously reported biological activity of P. lentiscus, and may also assign a new potential role of P. lentiscus tissue extracts in human health care.

Anthocyanins↗
PubMedDate not supplied

Chemical and enzymatic hydrolysis of anthraquinone glycosides from madder roots.

For the production of a commercially useful dye extract from madder, the glycoside ruberythric acid has to be hydrolysed to the aglycone alizarin which is the main dye component. An intrinsic problem is the simultaneous hydrolysis of the glycoside lucidin primeveroside to the unwanted mutagenic aglycone lucidin. Madder root was treated with strong acid, strong base or enzymes to convert ruberythric acid into alizarin and the anthraquinone compositions of the suspensions were analysed by HPLC. A cheap and easy method to hydrolyse ruberythric acid in madder root to alizarin without the formation of lucidin turned out to be the stirring of dried madder roots in water at room temperature for 90 min: this gave a suspension containing pseudopurpurin, munjistin, alizarin and nordamnacanthal. Native enzymes are responsible for the hydrolysis, after which lucidin is converted to nordamnacanthal by an endogenous oxidase.

Anthraquinones↗
PubMedDate not supplied

Identification by HPLC-PAD-MS and quantification by HPLC-PAD of phenylethanoid glycosides of five Phlomis species.

The qualitative and quantitative determination of phenylethanoid glycosides in methanolic extracts of five species of the genus Phlomis (Lamiaceae) has been investigated using a new reversed-phase HPLC method combined with photodiode-array detection and electrospray/MS analysis. Forsythoside B, verbascoside, samioside, alyssonoside, isoverbascoside, leucosceptosides A and B and martynoside were detected. The quantification of the above constituents was performed using echinacoside as internal standard. Knowledge of the content of phenylethanoid glycosides contributes to the chemotaxonomy of the genus.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Structural studies of zoospore attractants from Trachelospermum jasminoides var. pubescens: taxifolin 3-O-glycosides.

(2S, 3S)-Taxifolin 3-O-arabinoside, a new dihydroflavonol glycoside, together with the known substances, (2R 3R)-taxifolin 3-O-arabinoside, astragalin, isoquercitrin, and cosmosiin, were isolated from the leaves of Trachelospermum jasminoides var. pubescens. Structural elucidation was carried out by spectroscopic methods, and the absolute configurations of C-2 and C-3 in taxifolin 3-O-arabinosides were determined on the basis of circular dichroism. Unlike the dihydroflavonol glycosides, (2R 3R)-taxifolin 3-O-glucoside and (2R, 3R-taxifolin 3-O-arabinoside, the novel (2S, 3S)-taxifolin 3-O-arabinoside is not effective as a zoospore attractant of the plant pathogenic fungus Aphanomyces cochlioides.

Apocynaceae↗
PubMedDate not supplied

Quantitative analysis of flavonol glycosides in Ginkgo biloba: a comparison of two analytical methods.

A comparison of testing methods for constituents of Ginkgo biloba was performed as part of the process for determining which of the many available analytical methods was most appropriate for inclusion in the American Herbal Pharmacopoeia (AHP). Three primary methods were reviewed: those adopted by the European Pharmacopoeia, the National Science Foundation-Institute for Nutraceutical Advancement (NSF-INA) and the United States Pharmacopeia. Methods were compared by evaluating sample preparation and hydrolysis, precision and methods of total flavonol glycoside calculation by two independent laboratories. The AHP adopted the method of NSF-INA for inclusion in the AHP monograph owing to observed superiority of this method in terms of precision, glycoside calculation, ease of sample preparation and chromatographic parameters.

Chromatography, High Pressure Liquid↗
PubMed2005

Molecular modeling of cardiac glycoside binding by the human sequence monoclonal antibody 1B3.

The amino acid sequences of the heavy- and light-chain variable regions of the high-affinity human sequence antidigoxin monoclonal antibody 1B3 (mAb 1B3) were determined, and a structural model for the mAb's variable region was developed by homology modeling techniques. The structural model provided the basis for computationally docking digoxin and eight related cardiac glycosides into the putative binding site of mAb 1B3. Analysis of the consensus binding mode obtained for digoxin showed that the cardenolide moiety of digoxin is deeply embedded in a predominantly hydrophobic, narrow cavity, whereas the terminal, gamma-carbohydrate group is solvent-exposed. The docking results indicated that the primary driving forces for digoxin binding by mAb 1B3 are hydrophobic interactions with the digoxin steroid ring system and hydrogen bonds with the digitoxose groups. The binding model accounts for the experimentally observed variations in mAb 1B3 binding affinity for various structural analogs of digoxin used previously to develop a 3D structure-activity relationship model of drug binding (Farr CD, Tabet MR, Ball WJ Jr, Fishwild DM, Wang X, Nair AC, Welsh WJ. Three-dimensional quantitative structure-activity relationship analysis of ligand binding to human sequence antidigoxin monoclonal antibodies using comparative molecular field analysis. J Med Chem 2002;45:3257-3270). In particular, the hydrogen bond pattern is consistent with the unique sensitivity of mAb 1B3's binding affinity to the number of sugar residues present in a cardiac glycoside. The hydrophobic environment about the steroid moiety of digoxin is compatible with the mAb's reduced affinity for ligands that possess hydrophilic hydroxyl and acetyl group modifications in this region. The model also indicated that most of the amino acid residues in contact with the ligand reside in or about the three complementarity determining regions (CDRs) of the heavy chain and the third CDR of the light chain. A comparison of the 1B3 binding model with the crystal structures of two murine antidigoxin mAbs revealed similar binding patterns used by the three mAbs, such as a high frequency of occurrence of aromatic, hydrophobic residues in the CDRs and a dominant role of the heavy chain CDR3 in antigen binding.

Amino Acid Sequence↗
PubMed2003

In vitro immunomodulatory activity of flavonoid glycosides from Urtica dioica L.

The major compounds isolated from the methanolic extract of the aerial parts of Urtica dioica L. were determined as quercetin-3-O-rutinoside (1). kaempherol-3-O-rutinoside (2). and isorhamnetin-3-O-glucoside (3). by chromatographic, chemical (acidic hydrolysis) and spectral (UV, IR, (1)H-NMR, (13)C-NMR) methods. Their immunomodulatory activities were studied in vitro by chemotaxis (Boyden Migration Chamber) and intracellular killing activity (NBT reduction) tests. Compounds 1, 2, 3 and the total flavonoid fraction were determined to have significant chemotactic effects in 4, 8, 16 microg doses. According to the results of the NBT reduction test, all flavonoid glycosides showed high intracellular killing activity. The results of both assays confirmed the immunostimulatory activity of the flavonoid fraction and the isolated flavonoid glycosides on neutrophils suggesting that they could possibly be useful for treating patients suffering from neutrophil function deficiency and chronic granulomatous diseases.

Adjuvants, Immunologic↗
PubMed2006

Anticomplement activity of cycloartane glycosides from the rhizome of Cimicifuga foetida.

A tetranor-cycloartane glycoside and two 9,19-cycloartane glycosides were isolated from the EtOAc-soluble fraction of the rhizome of Cimicifuga foetida. The structures of the compounds were determined to be cimilactone A (1), 25-O-acetylcimigenol 3-O-beta-d-xylopyranoside (2) and cimigenol 3-O-alpha-l-arabinopyranoside (3), respectively, using spectroscopic analysis. The three compounds were examined for their anticomplement activity against the classical pathway of the complement system. Compound 1 showed significant anticomplement activity with an IC(50) value of 28.6 microm, whereas compounds 2 and 3 were inactive.

Animals↗