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PubMed1985

[Changes of affinity and capacity of cardiac glycoside receptors].

The receptor for cardiac glycosides probably is identical with the (Na+ + K+)-ATPase (approximately 250 000 Daltons). Its affinity for the therapeutically used glycosides is extremely different in different species (KD approximately 10(-9)M (human heart) - approximately 10(-7)M (rat heart]. In the latter, two distinct receptor types have been demonstrated (high- and low-affinity receptors) with different effects. In the human heart, there may be two cardiac glycoside receptors as well, although this has not been proved as yet. The number of cardiac glycoside receptors and their affinity is regulated in certain states and diseases. An increased receptor density is found in hyperthyroid states, in chronic hypokalaemia and in chronic digitalis treatment. A decreased number is measured in ischemic heart disease, in dilated cardiomyopathy and in hypothyroidism. Parallel to the decreased receptor density the maximal cardiac glycoside induced positive inotropy is reduced. Pronounced toxicity occurs, if the digitalis dose is increased in spite of missing effects.

Aging↗
PubMed1980

[Glycoside therapy in elderly patients (author's transl)].

Despite decreasing renal function with increasing age, an elevated level of serum glycoside concentration is not noted in elderly patients after undergoing continuous therapy with 0,2 or 0,3 mg beta-methyldigoxin, 0,4 mg beta-acetyldigoxin or 0,5 mg digoxin respectively, as long as the serum creatinine is still normal. Therefore, it is sufficient to determine the serum creatinine level before initiating glycoside therapy with digoxin or digoxin derivates. As a rule, a continuous oral therapy using 0,2 mg beta-methyldigoxin, 0,3 mg beta-acetyldigoxin or 0,375 mg digoxin can be carried out on elderly patients having a normal serum creatinine level, without risk and without danger of toxic side-effects. There is evidence that glycoside tolerance is decreased in the elderly. In elderly patients with a serum concentration level of 2,3 ng/ml or higher, 87% showed toxic side-effects, whereas in the younger age group only 72% of the patients with equally high serum glycoside concentrations were intoxicated. Therefore, oral doses exceeding 0,2 mg beta-methyl-digoxin, 0,3 mg beta-acetyldigoxin, or 0,375 mg digoxin should be carefully controlled by EKG in elderly patients. The most frequent cause of intoxication in elderly patients (75% of the cases) was an impaired renal function with elevation of the serum creatinine level,--a factor which was not taken into consideration in determining the glycoside dosage.

Acetyldigoxins↗
PubMed1983

Comparison of the inotropic potencies of some synthetic and naturally occurring cardiac glycosides using isolated left atrium of guinea pig.

The inotropic activity of 19 cardioactive steroids was determined using the electrically driven left atrium of the guinea pig. The compounds tested included five alpha-L-rhamnosides and four alpha-L-thevetosides. These were compared with their related genins and with representative examples of beta-D-glycosides. The study showed that rhamnosides and thevetosides were amongst the most active of all cardiac glycosides. The high activity of these compounds was probably related to the alpha-L-glycoside linkage and the configuration of the 4'-hydroxyl group and the 5'-methyl group. There was a stepwise loss of activity when the hydroxyl groups of the sugars were acetylated. The extent to which rhamnose enhanced the potency of different genins varied with the nature of the genin and ranged from 6- to 35-fold. The great variation in the published values for some of the glycosides tested demonstrates the need to standardize methods for testing cardiac glycosides.

Animals↗
PubMed1982

[Characteristics of membrane activity of triterpene glycosides].

The membrane activity of 6 triterpenic glycosides was studied with respect to ionic permeability of the liposomes and flat bilayer lipid membranes. It was shown that the rate of the glycoside effect depended on both the sterol level in the membrane and the sterol type (cholesterol, ergosterol). The activity of cauloside C, a plant glycoside markedly depended on pH of the medium. The carbohydrate chain played an important role in the membrane activity of the glycosides. Correlation in the effect of triterpenic glycosides on the model lipid and cell membranes was noted.

Cell Membrane↗
PubMedDate not supplied

[Effect of triterpene glycosides on the stability of bilayer lipid membranes, containing different sterols].

Low concentrations of triterpene glycosides: holothurin A, stichoposide A and cauloside C sharply change the stability of bilayer lipid-sterine membranes. The glycosides activity decreases in the line: holothurin A, stichoposide A, cauloside C. The effective doses of glycosides are to a great extent determined by structural peculiarities of sterines which compose the films. A correlation was observed between the effect of triterpene glycosides on the stability of model bilayer membranes and their physiological activity. The model lipid-sterine membranes can be used in the primary screening of triterpene glycosides to estimate their physiological activity.

Drug Stability↗
PubMedDate not supplied

[Immunomodulating activity of tetracyclic triterpene glycosides of the dammarane and holostane series].

Immunomodulating activity of triterpene glycosides of the holostan series (holoturins A and B, holoturin A2 and holotoxin A1) and triterpene glycosides of the dammaran series (3-O-monoglycoside,12-O-monoglycoside and 20-O-monoglycoside of protopanaxadiol and 3-O-monoglycoside of betulafolientriol) was studied in vitro. In low concentrations the triterpene glycosides showed mitogenic activity and modulated the immune response. The similarity in the action of the glycosides was first of all observed with respect to the dose-dependent duality of their effects i.e. the diametrically opposite action of the high and low doses. The expression of the effects was likely determined by the chemical structure of the triterpene glycosides. Liberation of the soluble mediators served as a secondary signal to the clonal expansion and differentiation of the cells.

Adjuvants, Immunologic↗
PubMed1976

[Concentration of cardiac glycosides in the heart and brain (author's transl)].

In cats the concentration of cardio-active glycosides in the heart and brain were investigated with trititum-labelled substances. Steady-state conditions were achieved by repeated i.v. injections of ouabain, digoxin, beta-methyldigoxin, digitoxin, and oleandrin over 5 days. 5 h after the last application glycoside concentrations were measured in plasma, urine, heart, cerebrum and cerebellum. Furthermore the metabolic pattern in these compartments was determined. 1. The glycoside concentration in the heart per g wet weight ranges only from 0.93 (oleandrin) to 1.88% (ouabain) of the daily administered dose per kg. 2. The concentrations in the brain show much higher differences between the diverse glycosides: ouabain with a concentration of 0.02%/g wet weight in the cerebrum shows the lowest and oleandrin with 1.60% the highest value. 3. By calculating the mean relative weights for the hearts (3.9 g/kg) and the brains (11.1 g/kg) 3.7% of the daily administered ouabain activity were found in the whole heart and only 0.18% in the whole brain. In contrast to these data the content of heart and brain after giving the more lipophilic oleandrin was 3.6% and 17.7% (!), respectively. 4. Under steady-state conditions the glycosides ouabain, digoxin, beta-methyldigoxin and digitoxin in heart and brain are mainly unchanged whereas oleandrin is transformed at a higher rate to polar metabolites.

Animals↗
PubMed2007

Glycosidation-anomerisation reactions of 6,1-anhydroglucopyranuronic acid and anomerisation of beta-D-glucopyranosiduronic acids promoted by SnCl(4).

The reaction of silylated nucleophiles with 6,1-anhydroglucopyranuronic acid (glucuronic acid 6,1-lactones) catalysed by tin(IV) chloride provides 1,2-trans or 1,2-cis (deoxy)glycosides in a manner dependent on the donor structure. The alpha-glycoside was obtained for reactions of the donor with the 2-acyl group and 2-deoxydonors, whereas the 2-deoxy-2-iodo donor gave the beta-glycoside. Experimental evidence shows that when 1,2-cis-glycoside formation occurs, the anomerisation of initially formed 1,2-trans-glycosides catalysed by SnCl(4) is possible. The anomerisation of beta-D-glucopyranosiduronic acids was found to be faster, in some cases, than anomerisation of related beta-D-glucopyranosiduronic acid esters and beta-D-glucopyranoside derivatives and the rates are dependent on the structure of the aglycon. Moreover, the rates of anomerisation of beta-D-glucopyranuronic acid derivatives can be qualitatively correlated with rates of hydrolysis of beta-D-glucopyranosiduronic acids. Mechanistic possibilities for the reactions are considered.

Glycosylation↗
PubMed2006

Liquid chromatography/tandem mass spectrometric study and analysis of xanthone and secoiridoid glycoside composition of Swertia chirata, a potent antidiabetic.

Swertia chirata is a bitter plant, used in the Indian system of medicine (Ayurveda) for various human ailments. The bioactive constituents include the xanthone and secoiridoid glycosides consisting of mangiferin, amarogentin, amaroswerin, sweroside and swertiamarin. Methanolic extracts of S. chirata possess constituents with antidiabetic activities, which was investigated by high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS). Preliminary HPLC analyses were performed on a reversed-phase C18 column using gradient elution. In the LC/ESI-MS spectra, predominant [M+H]+ and [M+Na]+ ions were observed in positive ion mode and provided molecular mass information. The five components of S. chirata were structurally correlated and confirmed based on the fragmentation characteristics and information available in the literature. The fragmentation behavior of [M+H]+/[M+Na]+ ions of these components were deduced from the collision-induced dissociation (CID) spectra obtained from the selective on-column information-dependant acquisition (IDA) approach. Xanthone-C-glycoside showed characteristic fragment ions due to fragmentation in the C-glycosidic unit while iridoid-O-glycosides showed characteristic fragment ions due to cleavage in the glycoside linkage and retro-Diels-Alder (RDA) cleavage within an iridoid aglycone. Furthermore, on the basis of this information, an analytical assay was developed and validated to determine relative concentrations of mangiferin, amarogentin, amaroswerin, sweroside and swertiamarin. The detection was carried out using multiple reaction monitoring (MRM) in positive ionization mode with a total analysis time of 3.5 min. The method was successfully applied to standardize four different batches of herbal preparation on the basis of relative concentration of five bioactive components.

Chromatography, Liquid↗
PubMed1977

[Determination of glycoside concentrations in human tissue by means of radioimmunoassay (author's transl)].

After extraction of myocardial and skeletal muscle biopsy and autopsy specimens tissue glycoside concentrations can be determined by radioimmunoassay. Total tissue extraction of digoxin and beta-methyl-digoxin varies between 87 and 95%, the variation coefficient for repeated determinations is 10.2%. Glycoside concentrations of left ventricular papillary muscle obtained after mitral valve replacement were 69.0 +/- 25.05 ng/g with a tissue to serum relation of 46.6 +/- 8.96:1 and a correlation coefficient of r = 0.8442. In autopsy left ventricular papillary muscle glycoside concentrations were 105.2 +/- 27.35 ng/g with an almost identical tissue to serum relation of 46.2 +/- 9.57:1 and a corresponding serum concentration of 2.3 +/- 0.63 ng/ml. In adults glycoside concentrations of autopsy specimens of the right ventricle were significantly lower by 28 to 30% than those of the left ventricle. Glycoside concentrations of skeletal muscle specimens (m. pectorialis major) were 14.7 +/- 10.35 ng/g with a tissue to serum relation of 9.7 +/- 3.00:1 (r = 0.8377), which corresponds to approximately 1/5 to 1/4 of the concentrations of the left ventricular myocardium.

Aged↗
PubMed2004

DNA stability and lipid peroxidation in vitamin E-deficient rats in vivo and colon cells in vitro--modulation by the dietary anthocyanin, cyanidin-3-glycoside.

BACKGROUND: Fruit and vegetable consumption protects against cancer. This is attributed in part to antioxidants such as vitamin E combating oxidative DNA damage. Anthocyanins are found in significant concentrations in the human diet. However, it remains to be established whether they are bioactive in vivo. AIM: To investigate the consequence both of vitamin E deficiency on oxidative damage to DNA and lipids and the cytoprotective effect of nutritionally relevant levels of cyanidin-3-glycoside both in vivo in rats and in vitro in human colonocytes. METHODS: Male Rowett Hooded Lister rats were fed a diet containing less than 0.5 mg/kg vitamin E or a vitamin E supplemented control diet containing 100 mg d alpha-tocopherol acetate/kg. Half of the controls and vitamin E-deficient rats received cyanidin-3-glycoside (100 mg/kg). After 12 weeks endogenous DNA stability in rat lymphocytes (strand breaks and oxidised bases) and response to oxidative stress ex vivo (H2O2; 200 microM) was measured by single cell gel electrophoresis (SCGE). Tissue levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-Oxo-dG) were measured by HPLC with EC detection. D alpha-tocopherol and lipid peroxidation products (thiobarbituric acid reactive substances; TBARS) were measured by HPLC. Rat plasma pyruvate kinase and the production of reactive oxygen by phagocytes were detected spectrophotometrically and by flow cytometry respectively. Immortalised human colon epithelial cells (HCEC) were preincubated in vitro with the anthocyanins cyanidin and cyanidin-3-glycoside and the flavonol quercetin (all 50 microM) before exposure to H2O2 (200 microM). DNA damage was measured by SCGE as above. RESULTS: Plasma and liver d alpha-tocopherol declined progressively over 12 weeks in rats made vitamin E deficient. Lipid peroxidation was increased significantly in plasma, liver and red cells. Reactive oxygen levels in phagocytes and plasma pyruvate kinase were increased. Vitamin E deficiency did not affect DNA stability in rat lymphocytes, liver or colon. Cyanidin-3-glycoside did not alter lipid peroxidation or DNA damage in rats. However, it was chemoprotective against DNA damage in human colonocytes.DNA strand breakage was decreased 38.8 +/- 2.2% after pretreatment with anthocyanin. CONCLUSION: While it is accepted that vitamin E alters lipid oxidation in vivo, its role in maintaining DNA stability remains unclear. Moreover, whereas cyanidin-3-glycoside protects against oxidative DNA damage in vitro, at nutritionally relevant concentrations it is ineffective against oxidative stress in vivo.

Animals↗
PubMed1989

Inter-species variations in myocardial responsiveness to cardiac glycosides: possible relations to the thyroid status.

Mammalian species differ in their myocardial responsiveness to cardiac glycosides; whereas glycosides induce a marked positive inotropic effect in species such as dog, rabbit and guinea-pig, the rat myocardium is virtually insensitive. We investigated the physiological basis for this phenomenon by testing the hypothesis that the inter-species variations in the response of the myocardium to cardiac glycosides results, at least in part, from species-related differences in the "thyroid status". In the present study we focused on the toxic effects of the glycosides, and studied ouabain-induced delayed afterdepolarizations (DAD): (1) in guinea-pigs, rats and mice, which encompass a wide range of thyroid statuses, as indicated by their O2 consumption and thyroid hormone levels; (2) in guinea-pigs and rats in which the thyroid status was decreased by propylthiouracil treatment or increased by thyroxine administration (in the former species only). DAD were readily induced in guinea-pigs after 40 to 60 min superfusion with 10(-6) M ouabain and 5.4 mM Ca2+. In rats, DAD were induced only when the Ca2+ concentration was raised to 8.1 mM, but were absent in mice even after 2 h of superfusion with ouabain and 8.1 mM Ca2+. In guinea-pigs and rats (at cycle length = 500 ms), DAD amplitude was (means +/- S.E.): 2.8 +/- 0.7 mV and 1.1 +/- 0.4 mV, respectively. The slope of the DAD ascending limb (dV/dt) in guinea-pigs was 47.6 +/- 8.6 mV/s and in rats was 8.1 +/- 3.4 mV/s. In both species DAD characteristics were altered by the thyroid status. In eu-, hyper- and hypothyroid guinea-pigs, DAD amplitude and dV/dt (cycle length = 500 ms) were as follows: 2.8 +/- 0.7 mV and 47.6 +/- 8.6 mV/s; 1.2 +/- 0.4* mV and 12.6 +/- 3.9* mV/s; 7.5 +/- 0.6* mV and 204.0 +/- 18.4* mV/s, respectively (*, P less than 0.005, compared to euthyroid guinea-pigs). The occurrence of triggered beats was also dependent on the thyroid status. They occur more frequently in hypothyroidism and less frequently in hyperthyroidism. Hypothyroidism in rats augmented ouabain toxicity as reflected by an increase in DAD amplitude and dV/dt by 109% and 105%, respectively (P less than 0.05, as compared to euthyroid rats). In conclusion, we suggest that species-related differences in the thyroid status may contribute to the inter-species (as well as for the intra-species) variations in the myocardial responsiveness to cardiac glycosides.

Action Potentials↗
PubMed2004

Enzymatic glycosidation of sugar oxazolines having a carboxylate group catalyzed by chitinase.

Enzymatic glycosidation using sugar oxazolines 1-3 having a carboxylate group as glycosyl donors and compounds 4-6 as glycosyl acceptors was performed by employing a chitinase from Bacillus sp. as catalyst. All the glycosidations proceeded with full control in stereochemistry at the anomeric carbon of the donor and regio-selectivity of the acceptor. The N,N'-diacetyl-6'-O-carboxymethylchitobiose oxazoline derivative 1 was effectively glycosidated, under catalysis by the enzyme, with methyl N,N'-diacetyl-beta-chitobioside (4), pent-4-enyl N-acetyl-beta-D-glucosaminide (5), and methyl N-acetyl-beta-D-glucosaminide (6), affording in good yields the corresponding oligosaccharide derivatives having 6-O-carboxymethyl group at the nonreducing GlcNAc residue. The N,N'-diacetyl-6-O-carboxymethylchitobiose oxazoline derivative 2 was subjected to catalysis by the enzyme catalysis; however, no glycosidated products were produced through the reactions with 4, 5, and 6. Glycosidation reactions of the beta-d-glucosyluronic-(1-->4)-N-acetyl-D-glucosamine oxazoline derivative 3 proceeded with each of the glycosyl acceptors, giving rise to the corresponding oligosaccharide derivative having a GlcA residue at their nonreducing termini in good yields.

Bacillus↗
PubMed1984

Measurement of hydroxylysine glycosides in urine and its application to spinal cord injury.

A new technique to evaluate the degradation of skin or bone collagen by measuring glucosylgalactosyl hydroxylysine and galactosyl hydroxylysine is presented. The method utilizes an automated amino acid analyzer. Eluents used are lithium buffers, and the color reagent is ninhydrin. Both glycosides elute in 3.5 h. Samples require minimum preparation. Urinary concentrations of both glycosides in ten patients with cervical spinal cord injuries of less than six months duration were higher than in five healthy controls. Proportional increases were different for each of the two glycosides. Variations in the proportional increase of each glycoside indicate different rates of degradation of skin and bone collagen. Repeated evaluations of the two urinary glycosides may help to predict whether patients are likely to develop skin- or bone-related clinical complications.

Adult↗
PubMed2002

Analysis of eleven iridoid glycosides by micellar electrokinetic capillary chromatography (MECC) and screening of plant samples by partial filling (MECC)-electrospray ionisation mass spectrometry.

Of ammonium, lithium and sodium salts of dodecyl sulfate studied as surfactants in the separation of iridoid glycosides by micellar electrokinetic capillary chromatography (MECC), the last one gave the best results. Eleven neutral iridoid glycosides were separated by MECC with sodium dodecyl sulfate as surfactant, and the water-micelle partition coefficients of the compounds were calculated. The separation system was coupled via a coaxial sheath flow electrospray interface to a mass spectrometer, and the partial filling technique was used in the on-line analysis. Seven plant species belonging to five genera (Plantago, Veronica, Melampyrum, Succisa and Valeriana) were screened for the iridoid glycosides by the new method that was developed. The findings confirmed those of an earlier study on five of the iridoid glycosides. Some new iridoid glycosides were found in Plantago lanceolata, Veronica spicata and V. chamaedrys.

Carbohydrate Conformation↗
PubMed1996

Fluorescence Anisotropy Assays Reveal Affinities of C- and O-Glycosides for Concanavalin A(1).

The free energies of binding of various C- and O-glycosides to the lectin concanavalin A were measured using fluorescence anisotropy. Fluorescein derivatives of mannose and glucose were synthesized and were shown to bind to concanavalin A with free energies of -5.1 and -4.3 kcal mol(-)(1), respectively. Competition experiments were performed to determine the binding energies of different nonfluorescent carbohydrates, and the results were in excellent agreement with the binding energies determined by microcalorimetry. The minimum carbohydrate epitope that fills the lectin carbohydrate binding site, methyl 3,6-di-O-(alpha-mannopyranosyl)-alpha-mannopyranoside, competes directly for the site with the fluorescent ligands, indicating that the fluorescent ligands bind specifically. The binding affinities of C-glycosides to concanavalin A were compared with those of O-glycosides. The free energies of binding for corresponding C- and O-glycosides differed by less than 0.5 kcal mol(-)(1), indicating that recognition properties of C- and O-glycosides are very similar. It was found that for some ligands the use of a carbon linkage rather than an oxygen linkage caused the specificity of binding to decrease slightly.

Journal Article↗
PubMed2003

Effect of iridoid glycoside content on oviposition host plant choice and parasitism in a specialist herbivore.

The Glanville fritillary butterfly Melitaea cinxia feeds upon two host plant species in Aland, Finland, Plantago lanceolata and Veronica spicata, both of which produce iridoid glycosides. Iridoids are known to deter feeding or decrease the growth rate of many generalist insect herbivores, but they often act as oviposition cues to specialist butterflies and are feeding stimulants to their larvae. In this study, two iridoid glycosides (aucubin and catalpol) were analyzed by micellar electrokinetic capillary chromatography. We measured the spatial and temporal variation of iridoid glycosides in natural populations of the host plants of M. cinxia. We also analyzed the aucubin and catalpol content in plants in relation to their use by ovipositing females, and in relation to the incidence of parasitism of M. cinxia larvae in natural populations. The mean concentrations of aucubin and catalpol were higher in P. lanceolata than in V. spicata, and catalpol concentrations were higher than aucubin concentrations in both host species. Plantago lanceolata individuals that were used for oviposition by M. cinxia had higher aucubin concentrations than random plants and neighboring plants. Additionally, oviposition and random plants had higher catalpol concentrations than neighboring plants, indicating that ovipositing females select for high iridoid glycoside plants or that oviposition induces iridoid glycoside production in P. lanceolata. Parasitism by the specialist parasitoid wasp Cotesia melitaearum occurred most frequently in larval groups that were feeding on plants with low concentrations of catalpol, irrespective of year, population, and host plant species. Therefore, parasitoids appear to avoid or perform poorly in host larvae with high catalpol content.

Animals↗
PubMed2006

Functional analysis of a group A streptococcal glycoside hydrolase Spy1600 from family 84 reveals it is a beta-N-acetylglucosaminidase and not a hyaluronidase.

Group A streptococcus (Streptococcus pyogenes) is the causative agent of severe invasive infections such as necrotizing fasciitis (the so-called 'flesh eating disease') and toxic-shock syndrome. Spy1600, a glycoside hydrolase from family 84 of the large superfamily of glycoside hydrolases, has been proposed to be a virulence factor. In the present study we show that Spy1600 has no activity toward galactosaminides or hyaluronan, but does remove beta-O-linked N-acetylglucosamine from mammalian glycoproteins--an observation consistent with the inclusion of eukaryotic O-glycoprotein 2-acetamido-2-deoxy-beta-D-glucopyranosidases within glycoside hydrolase family 84. Proton NMR studies, structure-reactivity studies for a series of fluorinated analogues and analysis of 1,2-dideoxy-2'-methyl-alpha-D-glucopyranoso-[2,1-d]-Delta2'-thiazoline as a competitive inhibitor reveals that Spy1600 uses a double-displacement mechanism involving substrate-assisted catalysis. Family 84 glycoside hydrolases are therefore comprised of both prokaryotic and eukaryotic beta-N-acetylglucosaminidases using a conserved catalytic mechanism involving substrate-assisted catalysis. Since these enzymes do not have detectable hyaluronidase activity, many family 84 glycoside hydrolases are most likely incorrectly annotated as hyaluronidases.

Acetylglucosamine↗