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Cyanogenic glycosides and cyanohydrins in plant tissues. Qualitative and quantitative determination by enzymatic post-column cleavage and electrochemical detection, after separation by high-performance liquid chromatography.

A rapid, simple and reproducible high-performance liquid chromatography procedure is described for the qualitative and quantitative analysis of mixtures of cyanogenic glycosides. The separation is achieved by means of a reversed-phase (C8) column eluted with a phosphate buffer, pH 5.0, containing either 15 or 7.5% (v/v) methanol, 7.5% being necessary for resolution of epimeric pairs of the more hydrophilic glycosides. When this separation is combined with enzymatic post-column cleavage and electrochemical detection of the cyanide formed, a highly specific and very sensitive system is obtained. The method was applied to cyanogenic glycosides in crude plant tissue extracts, and compared with both a thin-layer chromatographic method and to a traditional determination of total cyanide released after hydrolysis. Sensitivity, selectivity and accuracy were found sufficient to enable its routine use for analysis of food and fodder samples, for example. Cyanohydrins could be detected qualitatively.

Chromatography, High Pressure Liquid↗

Application of mass spectrometry for identification and structural studies of flavonoid glycosides.

Mass spectrometry is an important tool for the identification and structural determination of flavonoid glycosides. The advantages of mass spectrometry are high sensitivity and possibilities of hyphenation with liquid chromatographic methods for the analysis of mixtures of compounds. Different desorption ionization methods allow the analysis of underivatized glycosides. A review of mass spectrometric techniques applied to the identification and structural studies of flavonoid glycosides is presented.

Chromatography, Liquid↗

Iridoid and megastigmane glycosides from Phlomis aurea.

From the leaves of Phlomis aurea, two new iridoids of unique structures named 3-epiphlomurin (1) and phlomurin (2), a new megastigmane glucoside phlomuroside (3) and a new benzyl alcohol glycoside having the structure benzyl alcohol-O-beta-xylopyranosyl-(1-->2)-beta-glucopyranoside (4) have been isolated together with four known iridoids auroside, lamiide, 8-epiloganin and ipolamiide, two known phenolic glycosides acteoside (verbascoside) and syringin, one known phenylethanoid glycoside 2-phenylethyl-O-beta-xylopyranosyl-(1-->2)-beta-glucopyranoside, one known lignan liriodendrin and three known flavonoids chrysoeriol-7-O-beta-glucopyranoside, acacetin-7-O-beta-glucopyranoside and luteolin-7-O-beta-glucopyranoside. The structures of the isolated compounds were verified by means of mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectral analyses.

Carbohydrate Conformation↗

Flavonol glycosides from the stems of Trigonella foenum-graecum.

Two kaempferol glycosides [kaempferol 3-O-beta-D-glucosyl(1-->2)-beta-D-galactoside 7-O-beta-D-glucoside and kaempferol 3-O-beta-D-glucosyl(1-->2)-(6"-O-acetyl)-beta-D-galactoside 7-O-beta-D-glucoside] as well as the quercetin glycoside [quercetin 3-O-beta-D-glucosyl(1-->2)-beta-D-galactoside 7-O-beta-D-glucoside] were isolated from the stems of Trigonella foenum-graecum L. (Leguminosae) along with a known kaempferol glycoside, lilyn [kaempferol 3-O-beta-D-glucosyl(1-->2)-beta-D-galactoside]. Their structures were established by analysis of chemical and spectral evidence.

Fabaceae↗

Proanthocyanidin glycosides and related polyphenols from cacao liquor and their antioxidant effects.

Purification of polar fractions from cacao liquor extracts gave 17 phenolics including four new compounds. The new compounds were characterized as a C-glycosidic flavan, an O-glycoside of a dimeric and two O-glycosides of trimeric A-linked proanthocyanidins, on the basis of spectroscopic data. Isolated polyphenols showed inhibitory effects on nicotinamide adenine dinucleotide phosphate-dependent lipid peroxidation in microsomes and on the autoxidation of linoleic acid. These effects were attributed to the radical-scavenging activity in the peroxidation chain reactions, based on the findings that the cacao polyphenols effectively scavenged the 1,1-diphenyl-2-picrylhydrazyl radical.

Animals↗

Glycosides of polyenoic branched fatty acids from myxomycetes.

The determination of chemical structures of five novel compounds, i.e. one multibranched polyunsaturated fatty acid ((2E,4E,7S,8E,10E,12E,14S)-7,9,13,17-tetramethyl-7,14-dihydroxy-2,4,8,10,12,16-octadecahexaenoic acid) and its four glycosides from seven different myxomycetes is described. The absolute configuration of both hydroxyl groups was determined. The glycosides containing glucose, mannose and rhamnose. These compounds were identified by means of 1H and 13C NMR, MS, UV and IR spectra. Three of them were identified in Arcyria cinerea (Bull.) Pers., two in A. denudata (L.) Wetts., and A. nutans (Bull.) Grev., Fuligo septica (L.) Wigg., Lycogala epidendrum (L.) Fries, Physarum polycephalum Schwein., and Trichia varia Pers. contained one of the identified glycosides each.

Fatty Acids, Unsaturated↗

Phenolic glycosides from Symplocos racemosa: natural inhibitors of phosphodiesterase I.

One new phenolic glycoside named benzoylsalireposide (1) along with one known phenolic glycoside named salireposide (2) have been isolated from Symplocos racemosa. Four other known compounds i.e. beta-amyrin (3), oleonolic acid (4), beta-sitosterol (5) and beta-sitosterol glycoside (6) were also isolated from this plant. The structure elucidation of the isolated compounds was based primarily on 1D- and 2D-NMR analysis, including COSY, HMQC, and HMBC correlations. The compound 1 and 2 showed inhibitory activity against snake venom phosphodiesterase I.

Animals↗

Acylated flavonoid and phenylethanoid glycosides from Marrubium velutinum.

From the aerial parts of Marrubium velutinum, one acylated flavonoid glycoside, chrysoeriol 7-O-(3",6"-di-O-E-p-coumaroyl)-beta-D-glucopyranoside, and two tetrasaccharidic phenylethanoid glycosides, velutinosides I-II, have been isolated together with ten known flavonoids and seven known phenylethanoid glycosides. The structures of the isolated compounds were established by means of NMR, MS, and UV spectral analyses.

Acylation↗

Lanosterol and tetranorlanosterol glycosides from the bulbs of Muscari paradoxum.

Three tetranorlanostane glycosides, named lucilianosides C-E, and three lanostane glycosides, named scillasaponins E-G, together with a known lanostane glycoside, were isolated from the MeOH extract of Muscari paradoxum (Liliaceae) bulbs, as confirmed by detailed analysis of their 1H, 13C, and two-dimensional NMR spectroscopic data, and by the results of hydrolytic cleavage. The isolated compounds were evaluated for their cytotoxic activity against HSC-2 human oral squamous cell carcinoma cells.

Antineoplastic Agents, Phytogenic↗

Pregnane glycosides from Sansevieria trifasciata.

Phytochemical analysis of the whole plant of Sansevieria trifasciata, one of the most common Agavaceae plants, has resulted in the isolation of four new pregnane glycosides. Their structures have been determined by spectroscopic analysis and acid- and alkaline-catalysed hydrolysis to be 1 beta,3 beta-dihydroxypregna-5,16-dien-20-one glycosides. This is believed to be the first report of the isolation of the pregnane glycosides from a plant of the family Agavaceae.

Carbohydrate Conformation↗

Biologically active clerodane-type diterpene glycosides from the root-stalks of Dicranopteris pedata.

The molecular structure of the biologically active diterpene alcohol isolated previously from the root-stalks of Dicranopteris pedata and Gleichenia japonica was confirmed to be (6S,13S)-cleroda-3,14-diene-6,13-diol by an X-ray crystallographic analysis, together with application of the octant rule to the Cotton effect observed in the CD spectrum of its 6-keto derivative. Further investigation of the root-stalks of D. pedata has resulted in the isolated two new glycosides, which were characterised as (6S,13S)-6-O-[beta-D-glucopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl] 13-O-[alpha-L-rhamnopyranosyl-(1-->4)-beta-D-fucopyranosyl] cleroda-3,14-diene and (6S,13S)-6-O-[beta-glucopyranosyl]-13-O-[beta-fucopyranosyl-(1-->2) -alpha-rhamnopyranosyl]-cleroda-3,14-diene. Of these two glycosides, the former glycoside accelerated the growth of the stems of lettuce and inhibited the growth of the roots.

Disaccharides↗

Stoloniferins VIII-XII, resin glycosides, from Ipomoea stolonifera.

Five new ether-soluble resin glycosides were isolated from whole plants of Ipomoea stolonifera. Their structures have been determined on the basis of chemical and spectral data. Similar to the resin glycosides previously isolated, all of them are monomers of a jalapinolic acid tetra- or penta-glycoside in which the sugar moiety is partially acylated by organic acids and also combined with the carboxy group of the aglycone to form a macrocyclic ester structure.

Carbohydrate Conformation↗

Cytochemical demonstration of the molecular forms of cardiac glycosides in the heart muscle.

Selective topo-optical staining of vicinal-OH groups with aldehyde-bisulphite-toluidine blue (ABT) has been used for studying the localization and molecular structural order of cardiac glycoside in heart muscle. The glycoside has strong metachromatic basophilia and negative birefringence. In addition to confirming the electron microscopic suitability of the ABT reaction has offered also ultrastructural evidence for the reliability of the topo-optical method. The localization appeared to be in extracellular connection with the outer side of sarcolemma membrane, internal surface of endothelial cell, and in the subsarcolemmal cysterne. The findings suggest that the topo-optical reaction is suitable for molecular analysis of cardiac glycoside.

Aldehydes↗

Effects of phenylpropanoid and iridoid glycosides on free radical-induced impairment of endothelium-dependent relaxation in rat aortic rings.

The protective effect of phenylpropanoid glycosides, forsythoside B and alyssonoside, and the iridoid glycoside lamiide, isolated from the aerial parts of Phlomis pungens var. pungens, against free radical-induced impairment of endothelium-dependent relaxation in isolated rat aorta was investigated. Aortic rings were exposed to free radicals by the electrolysis of the physiological bathing solution. Free radical-induced inhibition of the endothelium-dependent relaxation in response to acetylcholine was countered by incubation of the aortic rings before electrolysis with the aqueous extract (200 microg/ml), phenylpropanoid fraction (100 microg/ml) and iridoid fraction (150 microg/ml) of P. pungens var. pungens. Major components of the phenylpropanoid fraction forsythoside B and alyssonoside also prevented the inhibition of the acetylcholine response, at 10(-4) M concentration. However, the major component of iridoid fraction lamiide was found ineffective at the same concentration. The protective activity of phenylpropanoid glycosides against the free radical-induced impairment of endothelium-dependent relaxation may be related to their free radical scavenging property.

Animals↗

Acute intraperitoneal and oral toxicity of the leaf glycosidic extract of Trigonella foenum-graecum in mice.

The present study was carried out to determine the acute toxicity of the leaf glycosidic extract of Trigonealla foenum-graecum by estimation of its medium lethal dose (LD(50)) after oral and intraperitoneal administration to mice and also to identify the target organs for its possible toxic effects. The main target organ affected among the four organs studied (liver, kidney, stomach, small and large intestine) was the liver, where early degeneration with infiltration of mononuclear and mild hepatitis was found in some animals treated with toxic doses of glycosidic extract. It is concluded that the glycosidic extract of T. foenum-graecum leaves is considered to be safe and have minimal adverse effect.

Administration, Oral↗

Glycoside hydrolase production by an anaerobic rumen fungus Caecomyces communis.

The ruminal fungus Caecomyces communis was grown anaerobically either in a discontinuous cultivation system or in a fermentor with daily withdrawal and addition of fresh medium. Lowe and Orpin media were tested. The best culture conditions for glycoside hydrolase production were obtained in Lowe medium with daily fresh medium addition, whereas the Orpin medium with ruminal fluid was favourable to fungal growth and to the enzyme export process. Among glycoside hydrolases assessed in both culture fluid and cellular homogenate, beta-D-fucosidase activity was preponderant. Most studied enzymes were mainly associated with cells (from 50% to 99%). Glycoside hydrolase activities were constitutive, but their level was regulated by a carbon source. beta-D-fucosidase and beta-D-xylosidase activity production was activated by the association of glucose plus cellobiose, whereas beta-D-glucosidase activity production was stimulated by cellobiose alone. Enzyme release could be favoured by glucose alone or by Ray grass hay added to glucose plus cellobiose.

Anaerobiosis↗

Inhibition of neuraminidase with neuraminic acid C-glycosides.

Neuraminic (sialic) acid based alpha-C-glycosides have been synthesized and their inhibitory activity towards bacterial neuraminidase (sialidase) was examined. While some C-glycosides were found to be potent inhibitors (Ki 15-30 microM) of this neuraminidase, others afforded no measurable activity. The structure-activity relationship of these C-glycosides is discussed in the context of other previously reported sialidase inhibitors.

Buffers↗