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PubMed2000

Pregnane glycosides from the roots of Asclepias tuberosa.

Sixteen glycosides of pregnanes, including ikemagenin, lineolon, and a new pregnane, 3beta8beta,14beta,15beta,16alpha-pentahydroxy-++ +5alpha-pregnan-20-one, termed pleurogenin, were isolated from the roots of Asclepias tuberosa. Among ikemagenin and lineolon glycosides, one (1) was a known glycoside, and eight (2-7, 10, 13) were glycosides with new combinations of ikemagenin or lineolon and known sugar sequences composed of D-cymarose, D-oleandrose, D-thevetose and D-glucose. The structures of four new glycosides of ikemagenin (8, 9, 11, 12) and three of pleurogenin (14-16) were determined. The new glycosides have sugar sequences ranging from tetraoside to heptaosides.

Glycosides↗
PubMed2006

Metabolism of tomato steroidal glycosides in humans.

Pregnane glycosides have been isolated in small amounts, along with the major components furostanol and spirostanol glycosides, from Dioscoreaceae, Taccaceae, and Solanaceae, suggesting that pregnane glycosides might be biosynthesized from furostanol and spirostanol glycosides. Recently, commercial natural foods composed of diosgenin have been used for the treatment of diseases such as osteoporosis and premenstrual syndrome in women. It is anticipated that diosgenin would be metabolized into a type of steroidal hormone, for instance progesterone, however, this metabolism has not been confirmed. Therefore, we have examined the metabolites in the urine of subjects who ingested tomatoes, which contain a considerable amount of the steroidal glycoside esculeoside A. The occurrence of steroidal hormones in the metabolites has been recognized. It has been proven that when a steroidal glycoside is administered, it is partly metabolized into a type of steroidal hormone exhibiting various physiological activities.

Adult↗
PubMed1987

[Triterpene glycosides and the structural-functional properties of membranes].

Triterpene glycosides have been found in many plant species and some marine animals. Many of these compounds are physiologically active and possess a broad range of medico-biological action. The physiological activity of triterpene glycosides is based on their ability to interact with the components of biological systems, primarily with sterols comprising the structure of biomembranes. The interaction of glycosides with sterols causes disturbance of selective permeability in plasmic membranes. Triterpene glycosides affect the liposome ionic permeability and flat bilayer lipid membranes. The rate of glycoside effect depends on quantitative and qualitative sterol level in the membrane. These compounds are used by organisms in the struggle for life and in maintaining the biological equilibrium in the antagonistic interactions of biological systems and ensure plant immunity against fungal diseases. Triterpene glycosides as substances of exogenous origin exhibit physiological activity towards warm-blooded animals. They affect the metabolism, the functional state of the organs and the organism as a whole.

Animals↗
PubMed1978

[The clinical significance of plasma glycoside concentrations in patients with cardiac pacemakers (author's transl)].

308 digitalized out-patients with artificial cardiac pacemakers were explored for signs of glycoside toxicity with simultaneous determination of digoxin plasma levels 12 hours after the last dose. The incidence of different side effects commonly attributed to overdigitalization did not allow prediction of toxic plasma levels. 55% of all glycoside levels were within the therapeutic range, 34% were below 0.7 ng/ml and only 11% above 2.0 ng/ml. With the most commonly prescribed maintenance doses of the glycosides used (digoxin 0.5 mg, beta-acetyldigoxin 0.4 mg, beta-methyldigoxin 0.2 mg, lanatosid C 1.0 mg) therapeutic plasma levels were reached regularly in 60-65% of the patients. A significant correlation existed between plasma glycoside concentrations and renal function as well as age, but glycoside concentrations could not be correlated with the age of the patients. There were no indications for interactions of the different glycosides prescribed with diuretics or oral antidiabetics.

Adult↗
PubMed1977

[Pharmacokinetics of cardiac glycosides and clinical consequences].

The purpose of pharmacokinetics of cardiac glycosides is to study the time courses of glycosides in biological fluids, tissues and excreta. The extent of accumulation of a given dose at uniform time intervals depends only from the overall elimination rate constant. By knowing the elimination rate constant the extent to which a cardiac glycoside would accumulate in the body following a fixed dosing regimen can be calculated. The higher accumulation in the central nervous system requires a much longer time. Therefore it may be assumed that the brain is a deep compartment for cardiac glycosides and this compartment cannot be detected by analysis of plasma glycoside concentrations. Central side effects of cardiac glycosides may occur at therapeutic plasma levels. In renal disease a lower maintenance dose of digoxin and methyldigoxin should be administered or the same dose less frequently. Digitoxin does not accumulate in patients with renal failure or in anuria since the extrarenal elimination of digitoxin is much higher compared to digoxin and methyldigoxin.

Biological Availability↗
PubMed2000

System-theoretical (Holistic) approach to the modelling of structural-functional relationships of biomolecules and their evolution: an example of triterpene glycosides from sea cucumbers (Echinodermata, holothurioidea).

Triterpene glycosides from sea cucumbers (Holothurioidea, Echinodermata) are used as a model for studying the biochemical evolution for correlation between the glycoside membranolytic activity and biological functions. Concepts of evolutionary morphology are applied at the molecular level. The concept of Van-der-Klaauve's- Dullemeijer's system-theoretical (holistic) approach is used for the model of structural-functional relationships of the glycosides. Network diagrams of structural-functional relationships have been prepared for many glycosides. The diagrams correlate well with experimental data and show a very complex and flexible action of the natural selection on the structural fragments of the glycosides. The diagrams also show overlapping in the functional components that provide stability to the general structural plan of glycosides during evolution. The method may be applied to other biomolecules.

Animals↗
PubMed1985

Cardiac glycoside tolerance in cultured chicken heart muscle cells--a dose-dependent phenomenon.

In cultured heart muscle cells from 10-13 day-old chicken embryos, the effects of acute (4 h) and chronic (3 days) exposure of the cells to varying concentrations of ouabain have been studied. In these cells, the cardiac glycoside ouabain binds to a specific cardiac glycoside receptor (KD = 4 X 10(-7) M; 750,000 receptors/cell). Binding to this receptor results in inhibition of active Na+/K+-transport [EC50 for active (86Rb+ + K+)-influx = 4 X 10(-6) M], and in an increase in beating velocity ("positive inotropic effect"; EC50 = 4 X 10(-7) M); toxic signs (arrhythmias) appear at concentrations greater than or equal to 6 X 10(-7) M. During exposure of the cells to 3 X 10(-6) M ouabain for 3 days, tolerance develops with respect to both the positive inotropic and the toxic effect. The mechanism underlying this tolerance is identified as an increase in the number of active sodium pump molecules per cell, while the binding properties of the cardiac glycoside receptor remain unchanged. The development of cardiac glycoside tolerance is only observed in the presence of severe impairment of Na+/K+-homeostasis, due to cardiac glycoside-induced inhibition of active Na+/K+-transport. This, however, only occurs in the presence of toxic (receptor occupation greater than or equal to 60%), but not in the presence of positive inotropic, non-toxic (receptor occupation 20-60%), ouabain concentrations. We conclude that the development of cardiac glycoside tolerance during long-term treatment in patients with heart failure should not occur with submaximal dose regimens, when toxic signs (arrhythmias) are absent.

Animals↗
PubMed1996

Purification and characterization of furostanol glycoside 26-O-beta-glucosidase from Costus speciosus rhizomes.

In plants, spirostanol glycosides (steroid saponins) are known to be formed furostanol glycosides during postharvest treatment and storage. Furostanol glycoside 26-O-beta-glucosidase (F26G) involved in this conversion was purified to apparent homogeneity for the first time from Costus speciosus rhizomes which accumulate these glycosides. The enzyme was highly specific for cleavage of the C-26-boudn glucose moiety of furostanol glycosides showing Km for protogracillin of 50 microM. Glucono-1,5-lactone, a typical beta-glucosidase inhibitor, and diosgenin, an aglycone of spirostanol glycosides, strongly inhibited the enzyme activity. The purified F26G is dimeric with a native apparent molecular weight of 110,000 consisting of subunits of 54,000 and 58,000. The N-terminal sequence of the 54,000 protein has a high similarity to the sequences found in N-terminal regions of known plant beta-glucosidases.

Amino Acid Sequence↗
PubMed1992

Flavonol glycoside production in callus cultures of Epimedium diphyllum.

Callus cultures of Epimedium diphyllum produced a large amount of epimedoside A in addition to a small amount of diphylloside B, ikarisoside C, epimedoside E, diglycosides of des-O-methylanhydroicaritin (8-gamma, gamma-dimethylallylkaempfero). Icariin, epimedins A-C, which are glycosides of anhydroicaritin, were also produced in the callus cultures. Contents of the flavonol glycosides in callus tissue were higher than those of mother plants, but the composition of each flavonol glycoside mixture in the callus cultures was different from that of the original plants. The time-course experiments showed that an inverse relationship existed between cell growth and flavonol glycoside production. Effects of hormonal factors on cell growth and flavonol glycoside production indicated that 2,4-dichlorophenoxyacetic acid was needed for the production of flavonol glycosides.

Carbohydrate Sequence↗
PubMed2001

Selective sequestration of iridoid glycosides from their host plants in Longitarsus flea beetles.

We investigated in eight species of the flea beetles genus Longitarsus (Coleoptera, Chrysomelidae) whether the beetles take up iridoid glycosides from their host plants of the Lamiaceae, Plantaginaceae, and Scrophulariaceae. Five of the beetle species, L. australis, L. lewisii, L. melanocephalus, L. nigrofasciatus, and L. tabidus, could be shown to sequester iridoid glycosides in concentrations between 0.40 and 1.55% of their dry weight. Eight different iridoid glycosides, acetylharpagide, ajugol, aucubin, catalpol, 8-epi-loganic acid, gardoside, geniposidic acid, and harpagide could be identified in the host plants, yet only aucubin and catalpol are sequestered by the beetles. No iridoid glycosides could be detected in the beetles if neither aucubin nor catalpol were present in the host plant, as in L. minusculus on Stachys recta (acetylharpagide only) and in L. salviae on Salvia pratensis (no iridoid glycosides). In one beetle species, L. luridus, we could not detect any iridoid glycosides although its field host, Plantago lanceolata, had considerable amounts of aucubin and catalpol plus two further iridoids. The five sequestering Longitarsus species differ in their capacity to store the compounds and in their affinity for catalpol relative to aucubin.

Journal Article↗
PubMed2000

Phenolic glycosides and condensed tannins in Salix sericea, S. eriocephala and their F1 hybrids: not all hybrids are created equal.

The performance of hybrids depends upon the inheritance and expression of resistance traits. Secondary chemicals are one such resistance trait. In this study, we measured the concentrations of phenolic glycosides and condensed tannins in parental and F1 hybrid willows to examine the sources of chemical variation among hybrids. S. sericea produces phenolic glycosides, salicortin and 2'-cinnamoylsalicortin, and low concentrations of condensed tannin in its leaves. In contrast, S. eriocephala produces no phenolic glycosides but high concentrations of condensed tannins in its leaves. These traits are inherited quantitatively in hybrids. On average, F1 hybrids are intermediate for condensed tannins, suggesting predominantly additive inheritance or balanced ambidirectional dominance of this defensive chemical from the parental species. In contrast, the concentration of phenolic glycosides is lower than the parental midpoint, indicating directional dominance. However, there is extensive variation among F1 hybrids. The concentration of tannin and phenolic glycosides in F1 hybrid families is either (1) lower than the midpoint, (2) higher than the midpoint, or (3) indistinguishable from the midpoint of the two parental taxa. It appears that the production of the phenolic glycosides, especially 2'-cinnamoylsalicortin, is controlled by one or more recessive alleles. We also observed a two-fold or greater difference in concentration between some hybrid families. We discuss how chemical variation may effect the relative susceptibility of hybrid willows to herbivores.

Journal Article↗
PubMed1996

Specificity of C-glycoside complexation by mannose/glucose specific lectins.

The binding of the mannose/glucose specific lectins from Canavalia ensiformis (concanavalin A) and Dioclea grandiflora to a series of C-glucosides were studied by titration microcalorimetry and fluorescence anisotropy titration. These closely related lectins share a specificity for the trimannoside methyl 3,6-di-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside, and are a useful model system for addressing the feasibility of differentiating between lectins with overlapping carbohydrate specificities. The ligands were designed to address two issues: (1) how the recognition properties of non-hydrolyzable C-glycoside analogues compare with those of the corresponding O-glycosides and (2) the effect of presentation of more than one saccharide recognition epitope on both affinity and specificity. Both lectins bind the C-glycosides with affinities comparable to those of the O-glycoside analogues; however, the ability of both lectins to differentiate between gluco and manno diastereomers was diminished in the C-glycoside series. Bivalent norbornyl C-glycoside esters were bound by the lectin from Canavalia but only weakly by the lectin from Dioclea. In addition to binding the bivalent ligands, concanavalin A discriminated between C-2 epimers, with the manno configuration binding more tightly than the gluco. The stoichiometry of binding of the bivalent ligands to both di- and tetrameric lectin was two binding sites per ligand, rather than the expected 1:1 stoichiometry. Together, these results suggest that concanavalin A may possess more than one class of carbohydrate binding sites and that these additional sites show stereochemical discrimination similar to that of the previously identified monosaccharide binding site. The implications of these findings for possible in vivo roles of plant lectins and for the use of concanavalin A as a research tool are discussed.

Calorimetry↗
PubMed2001

Iridoid glycosides from Globularia trichosantha.

A new iridoid glycoside, deacetylalpinoside (2), was isolated from the aerial parts of Globularia trichosantha together with nine known iridoid glycosides: catalpol, 10-O-benzoyl-catalpol, aucubin, asperuloside, deacetylasperuloside, asperulosidic acid, scandoside, geniposidic acid, and alpinoside (1). From the underground parts of the same plant, two new bisiridoid glycosides, globulosides A (3) and B (4); a known iridoid glycoside, globularidin; a lignan glycoside, liriodendrin; and seven phenylethanoid glycosides, arenarioside, verbascoside (= acteoside), isoacteoside, crenatoside, isocrenatoside, and trichosanthosides A and B, were isolated. Compounds 2-4 are new iridoids containing an 8,9 double bond representing a rare carbon skeleton. Their structures were established by spectroscopic methods.

Glucosides↗
PubMed1979

Cardenolide analogues: 10--characterization of cardiac glycosides by chemical ionization mass spectrometry.

The potential of chemical ionization mass spectrometry for the characterization of naturally occurring and semi-synthetic cardiac glycosides has been investigated. Methane, isobutane and ammonia were used as reactant gases. With the exception of ouabain, the ammonia chemical ionization mass spectra of the cardiac glycosides examined in this work contained abundant [M + NH4]+ions and abundant fragment ions formed by cleavage of glycoside bonds. Ammonia chemical ionization mass spectrometry was found to provide a rapid and sensitive method for the characterization of the products of glycosidation reactions. In contrast, the methane and isobutane chemical ionization mass spectra of the cardiac glycosides, with the exception of ouabain, did not contain protonated molecular ions and did not contain abundant fragment ions above m/z 400.

Ammonia↗
PubMed1965

CATALPOL AND METHYLCATALPOL: NATURALLY OCCURRING GLYCOSIDES IN PLANTAGO AND BUDDLEIA SPECIES.

1. A glycoside of the aucubin type has been isolated in crystalline form from Plantago and Buddleia species, and has been shown to be identical with catalpol (Lunn, Edward & Edward, 1962). Catalpol has not been found in the free state before, but occurs as its p-hydroxybenzoyl ester, catalposide, in the genus Catalpa. 2. A second glycoside of this type has been obtained in crystalline form from Buddleia, and has been shown to be a mono-O-methyl derivative of catalpol, for which the name ;methylcatalpol' is proposed. 3. Both Plantago and Buddleia species are known to contain aucubin. The concentrations of this glycoside and catalpol are comparable in Plantago. In Buddleia methylcatalpol predominates somewhat over catalpol. Yields of the individual glycosides were about 0.1% of the fresh weight of the leaves. 4. Bobbitt, Spiggle, Mahboob, Philipsborn & Schmid (1962) have suggested structures for catalposide and catalpol based on chemical and physical evidence, in particular on n.m.r. spectra. Reappraisal of this evidence and additional measurements have now confirmed these structures and show that the Buddleia glycoside is the 6-O-methyl derivative of catalpol.

Buddleja↗
PubMed1986

Further characterisation of the inotropic effect of a bufodienolide glycoside--an endogenous ouabain like compound.

A ouabain like compound obtained from toad skin and plasma and identified to be a steroidal bufodienolide glycoside was found to displace ouabain from its binding site and to inhibit Na+-K+ ATPase, and have positive inotropic effects on cardiac muscle. The ionic and rate dependence of this positive inotropy was studied in the frog atrium. The effect was dependent on extracellular potassium, sodium, and calcium concentrations and on the rate of stimulation, which is similar to the properties of cardiac glycosides. Occasionally, the compound gave transient or even negative inotropic responses, as do the glycosides. The action potential configuration was also affected by the compound in the same complex pattern as is that of cardiac glycosides. It is concluded that the endogenous bufodienolide compound has the same physiological effects as cardiac glycosides. Since the same compound is present in toad plasma it may serve as an intrinsic humoral regulator of cardiac contractility. This study is the first detailed characterisation of the cardioactive properties of this compound.

Action Potentials↗
PubMed1977

Some pharmacological studies on the cardiotonic effects of furanosteroidal glycosides.

Cardiotonic effects and cardiotoxicities of three furanosteroidal glycosides were compared with those of standard cardiac glycosides (digitoxin, gitoxin, etc.). Furanosteroidal glycosides showed positive inotropic effects in both isolated guinea-pig atria and rabbit hearts. The positive inotropic effect of 17beta-(3-furyl)-5beta,14beta-androstane-3beta,14,16beta-triol-3-bisdigitoxoside(FGBD) corresponded to that of digitoxin in isolated guinea-pig atria and frog hearts. Intravenous and oral administration of FGBD and 17beta-(3-furyl)-5beta,14beta-androstane-3beta,14,16beta-triol-3-tridigitoxoside(FGTD) in higher doses induced cardiac arrest after vomiting, bradycardia, ventricular rhythm, and ventricular fibrillation in pigeons and cats. Comparison of lethal doses between intravenous and oral administration of cardiac glycosides in pigeons and cats suggested that gastrointestinal absorption of FGBD and FGTD is inferior to that of digitoxin but superior to that of gitoxigenin bisdigitoxoside and gitoxin. Cardiotonic effects of furanosteroidal glycosides were confirmed in isolated guinea-pig, rabbit and frog hearts.

Androstanes↗
PubMedDate not supplied

Novel enzymatic approach to the synthesis of flavonoid glycosides and their esters.

Flavonoids such as (+)catechin can be efficiently solubilised in supersaturated solutions prepared with donor glycosides, e.g., p-nitrophenyl glycosides, di- and higher oligosaccharides, and poly(ethylene glycol) dimethyl ether in sufficiently high concentration for their efficient enzymatic glycosylation. Under these conditions several glycosidases readily accept (+)catechin as substrate and the target glycosides were prepared in one step in up to 26% yields. The regioselectivity of the reaction depends on the enzyme and substrate combination used; three positions, 5, 7, and 4', in the flavonoid can be glycosylated. The resulting and similar flavonoid glycosides were further modified by regioselective acylation with vinyl esters of arylpropenoic acids using lipases as biocatalyst. The efficiency of acylation was found to diminish in the order of vinyl cinnamate > vinyl ferulate > vinyl coumarate. This work demonstrates the feasibility of assembling complex flavonoid glycoside esters in just two steps by sequential use of commercially available glycosidases and lipases.

Acrylic Resins↗