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PubMed1996

Steroidal glycosides from Nicotiana tabacum L. seeds and their biological activity.

Steroidal glycosides of the spirostane and furostane series have been isolated from the methanolic extract of Nicotiana tabacum L. seeds by using gel filtration on silica gel and chromatography on a silica gel column. They were tentatively named nicotianosides A (1), B (2), C (3), D (4), E (5), F (6), and G (7). It has been shown that nicotianosides A (1), B (2), C (3), and D (4) are 3-O-beta-D-glucopyranoside-; 3-O-alpha-L-rhamnopyranosyl (1-->2)-O-beta-D-glucopyranoside-; 3-O-¿[alpha-L-rhamnopyranosyl (1-->2)].[alpha-L-rhamnopyranosyl (1-->4)]-beta-D-glucopyranoside¿: 3-O-¿[alpha-L-rhamnopyranosyl (1-->2)-alpha-L-rhamnopyranosyl (1-->3)]-alpha-L-rhamnopyranosyl (1-->4)]-beta-D-glucopyranoside¿: neotigogenin, respectively. The structures of nicotianosides E (5), F (6), and G (7) have been established as: 3-O-alpha-L-rhamnopyranosyl (1-->2)-O-beta-D-glucopyranoside; 3-O-¿[alpha-L-rhamnopyranosyl-(1-->2)]-[alpha-L-rhamnopyranosyl (1-->4)]-beta-D-glucopyranoside¿: 3-O-¿[alpha-L-rhamnopyranosyl (1-->2)-[alpha-L-rhamnopyranosyl (1-->3)]-alpha-L-rhamnopyranosyl (1-->4)]-beta-D-glucopyranoside): (25S)-5-alpha-furostane-3 beta, 22 alpha, 26-triol [-26-O-beta-D-glucopyranoside]. Growth-stimulating activities, prevention of virus attacks on tobacco, and a possible mechanism of action were established for the nicotianosides.

Carbohydrate Conformation↗
PubMed1996

A chemical study on the steroidal glycosides from Atropa belladonna L. seeds.

Eight steroidal glycosides of the spirostane type tentatively named atroposides A, B, C, D, E, F, G, and H (according to their increase in polarity) have been isolated from the methanolic extract of Atropa belladonna L. seeds by Sephadex gel filtration and column chromatography on silica gel impregnated with AgNO3. The structure of atroposides A, C, E, G has been elucidated as 3-O-alpha-D-galactopyranoside; 3-O-beta-D-glucopyranosyl(1-->4)-beta-D-galactopyranoside; 3-O-beta-D-glucopyranosyl (1-->2) -beta-D-glucopyranosyl(1-->4)-beta-D-galactopyranoside; and 3-O-alpha-L-rhamnopyranosyl (1-->4)-beta-D-glucopyranosyl (1-->2)-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside, each of (25R)-5 alpha-spirostane-3 beta-ol, respectively. The structure of atroposides B, D, F, and H has been elucidated as 3-O-beta-D-galactopyranoside; 3-O-beta-D-glucopyranosyl (1-->4)beta-D-galactopyranoside; 3-O-beta-D-glucopyranosyl (1-->2)-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside; 3-O-alpha-L-rhamnopyranosyl (1-->4)-B-D-glucopyranosyl (1-->2)-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside, each of (25R)-spirost-5-en-3-b-0l, respectively.

Atropa belladonna↗
PubMed1989

Multiple effects of cocaine upon evoked secretion in bovine adrenal medullary chromaffin cells. Additional insight into the mechanism of action of cardiac glycosides.

Experiments to determine the effects of the catecholamine neuronal uptake blockers cocaine and desipramine, and of the cardiac glycoside, ouabain, upon 3H-(noradrenaline) efflux have been performed with bovine adrenal medullary chromaffin cells in tissue culture. Both cocaine and desipramine reduced 3H-noradrenaline uptake into chromaffin cells. Inhibitable uptake was 80% of total accumulation over 60 min; this degree of inhibition was produced by cocaine (30 mumol/l) or desipramine (1 mumol/l). Cocaine (30 mumol/l) had no effect upon spontaneous 3H-efflux measured over 60 min, but reduced that evoked over the same period by carbachol (EC50), veratridine (EC50) and by ouabain (100 mumol/l). Cocaine did not reduce that efflux evoked by raised levels of K+ (28 mmol/l; EC50). Desipramine (1 mumol/l), like cocaine, had no effect upon spontaneous efflux of 3H, but reduced that efflux evoked by carbachol, veratridine and ouabain. Tetrodotoxin (TTX) inhibited veratridine-evoked 3H efflux (IC50 0.2 mumol/l). The degree of inhibition caused by TTX (0.2 mumol/l) was not increased by cocaine (30 mumol/l). TTX also inhibited ouabain-evoked 3H efflux: this was reduced by 55% by a concentration of TTX (1 mumol/l) sufficient to virtually abolish veratridine-evoked efflux. Cocaine (30 mumol/l) in the presence of TTX (1 mumol/l) did not further inhibit ouabain-evoked efflux. Cocaine (30 mumol/l) did not alter 86Rb+ uptake into chromaffin cells, nor did it alter that inhibition of 86Rb+ uptake produced by ouabain (100 mumol/l) indicating that cocaine has no effect upon Na,K-ATPase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Medulla↗
PubMed1986

Disposition and metabolism of the antitumor glycoside phyllanthoside in mouse and beagle dog.

Phyllanthoside is a naturally occurring glycoside with activity against IP transplantable murine tumors. Phyllanthoside administered IV, to mice at a nontoxic dose of 16 mg/kg could not be detected in blood or plasma even 30 s after administration. There was rapid formation of a less polar metabolite, which disappeared with a half-life of about 10 min. When phyllanthoside was administered as an IV bolus to beagle dogs at doses of 0.1, 0.5, and 3.0 mg/kg the mean half-life of phyllanthoside elimination from plasma was 1.3 min and total body clearance 85.8 ml min-1 kg-1. A second phase of elimination was seen but could not be accurately defined. Only trace amounts of the less polar metabolite were detected in dog plasma. Infusion of phyllanthoside to beagle dogs at doses of 0.5 and 3.0 mg/kg over 70 min gave values for an initial half-life of 0.3 and 0.6 min, a terminal half-life of 99.4 and 16.5 min, and a total body clearance of 11.2 and 49.2 ml min-1 kg-1, respectively. The highest nontoxic dose of phyllanthoside in dog was 0.1 mg/kg, while doses of 0.5 mg/kg and 3.0 mg/kg resulted in ataxia and death of the dog. There was no difference in toxicity to dog according to whether phyllanthoside was given by IV bolus or continuous infusion. Isolated hepatocytes from rat metabolized phyllanthoside at a rate of 4.4 micrograms/min per 10(6) cells to form the less polar metabolite. Coculture with isolated hepatocytes decreased the cytotoxicity of phyllanthoside to A204 human rhabdomyosarcoma cell line growing in soft agarose. It is suggested that rapid metabolism of phyllanthoside in mouse as against dog might account for the lower toxicity of phyllanthoside in mouse, and might also account for the reported poor antitumor activity of IV-administered phyllanthoside in the mouse.

Animals↗
PubMed1979

Biosynthesis of cyanogenic glycosides.

Cyanogenic glycosides are secondary plant compounds that occur widely in the plant kingdom. They are the source of HCN which can render the plant toxic if it is taken as food. The enzymes responsible for production of the HCN have long been known. More recent biosynthetic studies have established certain protein amino acids as precursors of the aglycones, and indicate N-hydroxyamino acids, aldoximes, nitriles and alpha-hydroxynitriles as intermediates. In sorghum the several biosynthetic enzymes catalyzing the flow of carbon atoms from L-tyrosine through such nitrogenous intermediates are located in a membrane fraction and may be capable of metabolic channeling.

Amino Acids↗
PubMed1989

Histochemical demonstration of O-glycosidically linked, type 3 based ABH antigens in human pancreas using lectin staining and glycosidase digestion procedures.

Histochemical analyses of the chemical structures of sugar sequences with or without blood group specificity were carried out by combined stepwise digestion of tissue sections with exo- and endoglycosidases and subsequent lectin stainings in formalin-fixed, paraffin-embedded human pancreas. In acinar cells from blood group A or AB secretor individuals, sequential digestion with alpha-N-acetylgalactosaminidase and alpha-L-fucosidase imparted reactivity with peanut agglutinin (PNA) in cells reactive with Dolichos biflorus agglutinin as well as those with Ulex europaeus agglutinin I(UEA-I). Simple fucosidase digestion imparted the PNA reactivity only in UEA-I reactive cells. Sequential digestion with alpha-galactosidase and fucosidase likewise liberated the PNA binding sites in Griffonia simplicifolia agglutinin I-B4 reactive cells from blood group B and AB secretors. Sialidase digestion liberated the PNA binding sites not only in acinar cells but also intercalated duct cells, islet cells of Langerhans and endothelial cells. The PNA reactivity obtained by these enzyme digestions was eliminted by endo-alpha-N-acetylgalactosaminidase (endo-GalNAcdase) digestion. Preexisting PNA affinity in acinar cells from non-secretors was also susceptible to endo-GalNAcdase treatment. Following the endo-GalNAcdase digestion, fucosidase or sialidase digestion recovered the PNA reactivity in acinar cells from nonsecretors. These results show that ABH determinants carried on O-glycosidically linked type 3 chain (D-galactose-(beta 1-3)-N-acetyl-D-galactosamine alpha 1-serine or threonine) are secreted in pancreatic acinar cells and suggest that product coded by the secretor gene is required for the complete conversion of type 3 precursor chains into H determinants.

ABO Blood-Group System↗
PubMed1982

Influence of 16 beta formylation on Na, K-ATPase inhibition by cardiac glycosides.

The inhibitory effect of formylated cardiac steroids (gitaloxin and its derivatives) on guinea-pig heart Na, K-ATPase was compared to that of other cardiac steroids with various hydroxy substituents. The decreasing order of potency of aglycones at equilibrium was as follows: gitaloxigenin greater than digitoxigenin greater than ouabagenin greater than digoxigenin greater than gitoxigenin greater than diginatigenin. This sequence was different to the sequence of drugs hydrophobic character. The compounds with hydroxy groups in the vicinity of the lactone ring (gitoxigenin, diginatigenin) were less potent than the hydrophilic compound ouabagenin. We propose that intramolecular bounding between 16 beta-OH and the lactone ring contributes to the relatively low potency of gitoxigenin and diginatigenin. The formylation of 16 beta-OH increased the potency of gitoxigenin by a factor of 41. The formylated compound (gitaloxigenin) was 5-fold more potent than digitoxigenin. The 3 beta-glycosylation of digoxigenin lead to pseudo-irreversible inhibitors of Na, K-ATPase. The half-time to achieve the equilibrium (for 5 mumol/l) was equal to 54 s, 90 s and 108 s respectively for digoxigenin monodigitoxoside, digoxin and desacetyllanatoside C. However, at equilibrium the three glycosides were equipotent, suggesting the existence of steric effects at the sugar site of the receptor. The sequence of potency observed for monodigitoxosides, monodigitalosides and tridigitoxosides after 60 min incubation was similar to that observed for the corresponding aglycones. These results suggest that the strongly negative inductive group 16 beta-OCHO is tightly bound to Na, K-ATPase, possibly to the same receptor site than that which is thought forming hydrogen and ionic bonds with the lactone ring. They show that the high toxicity of gitaloxin in guinea-pig heart is likely due to its high potency as Na, K-ATPase inhibitor.

Animals↗
PubMed1975

Cerebrovascular ultrastructural alterations after intra-arterial infusions of ouabain, scilla-glycosides, heparin and histamine.

Cardiac glycosides which inhibit Na/K-ATPase (ouabain, scilliroside, scillirosidin) as well as heparin and histamine were infused into a cannulated branch of the middle cerebral artery or by isolated head perfusion in cats and dogs. Ouabain permeating the blood-brain barrier (BBB) caused the same selective swelling of astrocytes and of certain presynaptic elements as after direct application to the brain tissue. The other cellular elements of brain tissue and the vascular endothelium did not react, although the latter was exposed to the highest drug concentrations (about 10-3 M ouabain). By the swelling about one third of the capillaries became more or less constricted accompanied by an increase in endothelial vesiculation and in the number of osmiophilic inclusions in all cells of the vascular wall and of the pericapillary tissue. Osmiophilic material resembling plasma proteins occured in widened intercellular clefts indicating an increased BBB permeability after survival times (40 min). In contrast to the capillaries some terminal vessels are dilated which may correspond to shunt vessels causing an inhomogeneous, even increased cerebral blood flow after ouabain. Scilliroside and scillirosidin cause essentially the same changes as ouabain, but of smaller intensity and extent. In the present study, neither histamine nor heparin caused any structural change of the vessels or brain tissue.

Animals↗
PubMed1993

A model for cleavage of O-glycosidic bonds in glycoproteins.

The present work investigated the possibility of cleavage of alpha-linkages between mannose or galactose and serine/threonine residues by alpha-mannosidase and alpha-galactosidase. The study was carried out initially with model synthetic compounds imitating the O-glycosidic bond in glycoproteins, and further with glucoamylase. It was shown that alpha-mannosidase and alpha-galactosidase can hydrolyse these linkages after proteolytic digestion of glucoamylase.

Glucan 1,4-alpha-Glucosidase↗
PubMed1992

Synthesis of O-glycopyranosyl-N-hydroxysuccinimides of glucose and lactose and their opening by nucleophiles into prespacer glycosides.

O-Glycopyranosyl-N-hydroxysuccinimides of glucose and lactose have been synthesized. Peracetylated sugars, acetobromo sugars and benzoylated thioethyl glycosides have been used as precursors. With boron trifluoride etherate in dichloromethane, peracetylated sugars gave predominantly the beta anomer. Trimethylsilyl trifluoromethanesulfonate in nitromethane, however, gave predominantly the alpha anomer. Treatment of the acetylated O-glucopyranosyl-N-hydroxysuccinimide with various nucleophiles (methoxide, hydroxide and pentylamine) gave the corresponding deacetylated N-(succinyl)glucopyranosylhydroxylamines in almost quantitative yield. These derivatives are suitable for the formation of glycoconjugates or attachment of carbohydrates to solid phases using the opened succinimide as linking arm.

Glucose↗
PubMed1989

Primary structure of the major O-glycosidically linked carbohydrate unit of human von Willebrand factor.

A reduced tetrasaccharide chain was obtained from human von Willebrand factor (vWF) by mild alkaline borohydride treatment. The purification of this O-glycosidically-linked oligosaccharide was achieved by serial affinity chromatography on immobilized concanavalin A and Lens culinaris agglutinin and finally gel filtration. Its structure was determined by a combination of methylation studies and 500 MHz 1H-NMR spectroscopy to be: NeuAc(alpha 2-3)Gal(beta 1-3)[NeuAc(alpha 2-6)]GalNAc-ol.

Carbohydrate Conformation↗
PubMed1989

Binding and precipitating activities of Erythrina lectins with complex type carbohydrates and synthetic cluster glycosides. A comparative study of the lectins from E. corallodendron, E. cristagalli, E. flabelliformis, and E. indica.

Erythrina lectins possess similar structural and carbohydrate binding properties. Recently, tri- and tetra-antennary complex type carbohydrates with non-reducing terminal galactose residues have been shown to be precipitated as tri- and tetravalent ligands, respectively, with certain Erythrina lectins [Bhattacharyya L, Haraldsson M, Brewer CF (1988) Biochemistry 27:1034-41]. The present work describes a comparative study of the binding and precipitating activities of four Erythrina lectins, viz., E. corallodendron, E. cristagalli, E. flabelliformis, and E. indica, with multi-antennary complex type carbohydrates and synthetic cluster glycosides. The results show that though their binding affinities are very similar, the Erythrina lectins show large differences in their precipitating activities with the carbohydrates. The results also indicate significant dependence of the precipitating activities of the lectins on the core structure of the carbohydrates. These findings provide a new dimension to the structure-activity relationship of the lectins and their interactions with asparagine-linked carbohydrates.

Carbohydrate Conformation↗
PubMed1977

Flavonoid glycosides and hydroxycinnamic acid esters of blackcurrants (Ribes nigrum). Phenolics of fruits 9.

The major flavonol glycosides of ripe blackcurrants (Ribes nigrum cv. Silvergieters Schwarze), myricetin 3-beta-D-glucopyranoside, rutin, and isoquercitrin, have been isolated in crystalline form. Analysis by thin-layer chromatography confirmed the occurrence of the 3-rutinosides and 3-glucosides of cyanidin and delphinidin. No free flavonoid aglycones could, however, be detected in the fresh berries. The major constituent fluorescing blue under ultraviolet light on paper and cellulose thin-layer chromatograms, was isolated and characterized as 1-O-caffeyl-beta-D-glucopyranose. Also isolated were 1-O-ferulyl- and 1-O-p-coumaryl-beta-D-glucopyranose. The occurrence fo hydroxycinnamyl-D-glucoses in blackcurrants does not appear to have been recognized previously.

Chromatography, Thin Layer↗
PubMed1995

Solasodine glycosides of Solanum unguiculatum (A.) Rich.

Besides solasonine, three new glycosides, namely, 3-O-alpha-L-rhamnopyranosyl-(1-->3)-solasodine, 3-O-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-rhamnopyranosyl-(1-->4)-beta -D- galactopyranosyl solasodine, and 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-galactopyranosyl solasodine, were isolated from Solanum unguiculatum (A.) Rich. Their structures were determined on the basis of chemical and spectral methods.

Carbohydrate Sequence↗
PubMed1978

The lack of insulin-binding to simple glycosidic receptors.

The results of affinity electrophoresis at pH 8.9 show that insulin does not interact with any of a number of glycosidic ligands which bind various lectins. The results are discussed with respect to some similarities between insulin and concanavalin A.

Binding Sites↗
PubMed1994

A new flavone glycoside from the fern Pteris cretica.

A new flavone glycoside isolated from the fern Pteris cretica has been shown to be luteolin 7-O-robinobioside (1) by chemical and spectral methods. In addition luteolin 7-O-rutinoside (2) and luteolin 7-O-glucoside (3) have been isolated from this plant. Flavonoid 2 is reported for the first time in ferns.

Flavonoids↗
PubMedDate not supplied

[A slide ruler and nomogram for calculations in cumulation kinetics of cardiac glycosides (author's transl)].

UNLABELLED: 1. Substance I, whose elimination we can approximate with an exponential function, is active in the organism. 2. At a given moment substance II with the same onset of action whose elimination we also can approximate with an exponential function but different from substance I, starts to be added at regular intervals. 3. The relative levels of the two substances can be added up. 4. The optimal dose-scheme for the most regular effect is to be sought. RESULTS: According to the relations derived in repost (5) published previously a slide ruler and a nomogram are constructed by the authors for that purpose. The scales are described as well as how to work with them. Some examples are included. The slide ruler and the nomogram are suitable for some further calcaulations in cumulation kinetics, which is briefly mentioned. These expedients are mainly meant for the application of cardiac glycosides. The same principle can be used in all cases to which the assumptions mentioned above apply.

Cardiac Glycosides↗
PubMed1989

Flavones and flavonol glycosides from Eupatorium cannabinum L.

The 6-methoxyflavones hispidulin and eupafolin have been identified for the first time from the aerial parts of Eupatorium cannabinum L. The presence of the previously known flavonol glycosides astragalin, kaempferol-3-rutinoside, hyperoside, isoquercitrin and rutin could be confirmed. Hispidulin, eupafolin and rutin were screened for cytotoxicity in vitro.

Animals↗