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At least 19 recordsLinked to original sources
PubMed1984

[Estimation of the effects of cardenolides. 1. Relation between molecular physical parameters and parameters of action of cardenolides].

Knowing the modell developed by Repke and co-workers for the cardenolide-receptor-interaction the aim of this study was to find quantitative relations between molecular physical properties of cardenolides and their molecular-biologically defined effect, which are fundamentally useful to estimate the effect of still nonsynthesized cardenolide derivatives. The statistically significant relations (alpha = 0.05) between molecular physical parameters, which are derived from the dipole moment vector, and the molecular-biologically defined effect was found by means of regression analysis.

Adenosine Triphosphatases↗
PubMed1978

Cardenolide analogues. 3. A fast thin layer chromatographic separation of cardenolide diastereomers.

Cardenolide diasteromeric mixtures may be analytically separated on 2.5 x 6.5 cm x 0.25 mm pre-coated silical gel 60 F-250 (EM) tlc plates (cut from 20 x 20 cm plates). Three successive developments in mixtures of CH2Cl2-EtOAc-MeOH achieve complete separation of diastereomers in less than 15 minutes, and 2--6 micrograms of sample is sufficient. This procedure facilitated the separation of several diastereomeric mixtures, including 20(R) and 20(S)-20,22-dihydrocardenolides. A single development produces separations sufficient for separating starting materials and products of common cardenolide types of reactions.

Cardenolides↗
PubMed1998

Synthesis of cardenolide glycosides and putative biosynthetic precursors of cardenolide glycosides.

A rapid and efficient procedure for glycosylation of steroids was established using a modified Koenigs-Knorr procedure. Peracetylated beta-glycosides were synthesized by reaction of cardenolides, various pregnanes and 23-nor-5,20(22)E-choldienic acid at room temperature with the peracetylated 1-bromo derivatives of D-glucose, D-galactose, D-fucose and cellobiose. Subsequent deprotection was performed by alkaline hydrolysis with sodium methoxide. Structures of the respective glycosides were established by NMR techniques. The complete protocol was shown to be non-destructive at all stages to the sugar moiety and the steroidal nucleus. The gamma-unsaturated lactone ring of the cardenolides was shown to remain intact and no formation of C-14 unsaturated compounds was observed.

Cardenolides↗
PubMed1984

Relationship between the inotropy speeds in guinea-pig myocardium and lipophilic character of cardenolides and ericaceous toxins.

Interrelation between lipophilic characters and speeds of positive inotropic effect (PIE) of cardenolides and ericaceous toxins was studied by determining both parameters of lipophilicity and inotropy speeds. The lipophilic characters of 8 kinds of cardenolides, evaluated from Rm or log k' values by means of thin layer chromatography (Rf) or high performance liquid chromatography (retention time), increased in the order of ouabain, digoxin, digitoxigenin, digitoxigenin-monodigitoxoside, digitoxigenin-bis-digitoxoside, digitoxin, alpha-acetyl-digitoxin, triacetyl-digitoxin. Lipophilic character, evaluated from Rm values of 6 kinds of ericaceous toxins, was in decreasing order of 10S-grayanotoxin II, 6-acetyl grayanotoxin I, asebotoxin I, grayanotoxin I, asebotoxin III, asebotoxin X. The speed with which PIE developed was evaluated from the time to half maximum PIE (T50) of cardenolides and ericaceous toxins at a pD2 concentration. The speed of positive inotropy of cardenolides was independent of their concentration tested in the range from half to twice the concentration of pD2, while the speeds of PIE of ericaceous toxins depended on their concentration in the same range used in case of cardenolides. Inotropy speed of these two classes of cardiotoxins correlated well with the lipophilic character: a) In the case of cardenolides, a positive and close correlation (r = 0.98) was observed between T50 and Rm. The more lipophilic the cardenolides, the more time was required to reach the fully development of PIE. b) In contrast, a negative correlation (r = -0.82, between Rm and T50) was obtained in the case of ericaceous toxins; Toxins with more lipophilic nature caused faster development of PIE. The present results can be interpreted to mean that the PIE receptor for cardenolides in myocardial cells is located on the outer surface of the sarcolemma, while that for ericaceous toxins is located on the inside of the myocardial cell.

Animals↗
PubMed1995

The cardenolides of Speirantha convallarioides.

The cardenolide pattern of Speirantha convallarioides has been investigated and compared with Convallaria majalis, a close relative with active cardenolides and used extensively as a cardiac remedy. Five cardenolides were isolated from small amounts (25 g) of plant material by application of an efficient isolation procedure. Their identification was achieved by an easy concept mainly based on detailed analysis of 1H-NMR and DCI-NH3-mass spectral data. Rhodexin A(1) and lokundjoside (2) are the major cardenolides (42% and 31% of the total cardenolides in the plant), while digitoxigenin-glucoside (3), periplorhamnoside (4), and periplogenin-glucoside (5) are minor constituents of the cardenolide complex (3 to 4% each). Similarities in cardenolide patterns (structures of the aglycones, variability of the sugar portion) along with morphological and biogenetical characteristics support the classification of S. convallarioides as belonging in the same tribe Convallarieae as C. majalis within the family Convallariaceae.

Carbohydrate Sequence↗
PubMed1998

The inhibition of fibroblast growth factor-2 export by cardenolides implies a novel function for the catalytic subunit of Na+,K+-ATPase.

Basic fibroblast growth factor (FGF-2) is one of a select group of proteins that can exit cells through an alternate, endoplasmic reticulum/Golgi apparatus independent exocytic pathway. This alternate pathway has been termed protein export. In an attempt to better understand this process, we have identified a family of related compounds, "cardenolides," that inhibit FGF-2 export. The cardenolides inhibit FGF-2 export in a time and concentration dependent fashion. Inhibition of FGF-2 export is specific in that the cardenolides have no effect on conventional protein secretion as measured by their inability to block release of the secreted protein human chorionic gonadotropin-alpha. Because cardenolides are known to inhibit ion transport activity mediated by Na+,K+-ATPase, we investigated whether there are functional interactions between FGF-2 and their only known molecular target: the alpha-subunit of Na+, K+-ATPase. Export of FGF-2 from COS-1 cells is selectively inhibited when co-transfected with expression vectors encoding the alpha-subunit and FGF-2. Moreover, antibodies to the alpha-subunit specifically co-immunoprecipitate FGF-2 along with the alpha-subunit while conversely, antibodies to FGF-2 specifically co-immunoprecipitate the alpha-subunit along with FGF-2. Finally, the ion transporting activities of the Na+,K+-ATPase can be uncoupled from protein export. Varying the external concentration of K+ has little effect on export of FGF-2. Taken together, these data: 1) identify a novel activity for cardenolides; 2) suggest a previously unknown role for the alpha-subunit of Na+, K+-ATPase in FGF-2 export; and 3) raise the possibility that the alpha-subunit itself may be an integral component of this alternate exocytic pathway mediating translocation of cytosolic FGF-2 to the cell surface.

Animals↗
PubMed1977

[Synthesis and characterization of some cardenolide glucuronides and sulphates (author's transl)].

Cardenolide glucuronides are synthesized in the following way: firstly cardenolide glucosides are prepared by the reaction with acetobromglucose; secondly the hydroxymethyl group of the glucose moiety is oxydized in presence of a platinum catalyst to the carboxyl group of the final glucuronic acid. Glucuronides of the following cardenolides are prepared and described: digoxin, digoxigenin, digitoxin, digitoxigenin-monodigitoxoside, digitoxigenin, and 3-epi-digitoxigenin. Sulphates of digoxigenin, digitoxigenin, and 3-epi-digitoxigenin are prepared by direct reaction of these cardenolides with chlorosulphonic acid in pyridine. The assumed structure of some conjugates has been confirmed by n.m.r. spectroscopy. A high water solubility (6.7-65.1 g/l), a minute chloroform solubility (0.0002-0.0005 g/l), and a low octanol/polar nature of these compounds. Inotropic or toxic cardiac activities of the conjugates are examined on isolated guinea pig papillary muscles and by the Hatcher method on cats. Conjugates with at least one digitoxose show cardioactivities comparable to digoxin or digitoxin. In contrast to that the conjugated genins indicate decreased activities which are at least one-tenth of the potency of the unconjugated glycosides.

Animals↗
PubMed1998

Inhibition of Na+,K+-ATPase by the cardenolide 6'-O-(E-4-hydroxycinnamoyl) desglucouzarin.

Among the major cardenolides from the milkweed Asclepias asperula, 6'-O-(E-4-hydroxycinnamoyl) desglucouzarin has not been characterized biochemically. In this study, its binding affinity for a physiological receptor, porcine kidney Na+,K+-ATPase, was found to be lower than the other cardenolides in this plant. The order of affinities from highest to lowest was: uzarigenin (Kd = 1.05 microM) = desglucouzarin (Kd = 0.98 microM) > uzarin (Kd = 4.0 microM) > 6'-O-(E-4-hydroxycinnamoyl) desglucouzarin (Kd = 16 microM). The chemical attachment of the 4-hydroxycinnamoyl group to the 6'-carbon of desglucouzarin significantly inhibits binding. This agrees with predictions that a 5'-methyl group on cardenolides fits the receptor site optimally for the porcine kidney enzyme. The 4-hydroxycinnamic ester was also found to be fluorescent.

Cardenolides↗
PubMed1978

Correlation between inhibition of (Na+, K+)-membrane-ATPase and positive inotropic activity of cardenolides in isolated papillary muscles of guinea pig.

Concentrations of 17 cardenolides, cardenolide glucuronides and sulfates producing half-maximal inhibition of (Na+, K+)-membrane-ATPase from different organs and animal species were determined in vitro. In addition the concentrations that increased the contractility of guinea pig isolated papillary muscles to a particular level were investigated. Comparisons between ATPase-inhibiting and positive inotropic cardiac activities showed extensive parallelism: the correlation coefficients after log/log transformation were between 0.92 and 0.97. The same close correlations are found if dissociation constants of cardenolide receptor complexes and concentrations causing 86Rb-uptake inhibition in human erythrocytes are examined. The concentrations necessary for inhibition of (Na+, K+)-membrane-ATPase of the guinea pig heart and the concentrations required to achieve a defined positive inotropic effect in guinea pig papillary muscle showed a log/log correlation coefficient of 0.97 (P less than 0.001). In both tests the potencies covered more than three orders of magnitude. The results support Repke's hypothesis on the digitalis receptor.

Animals↗
PubMedDate not supplied

Determination of cardenolides in hairy root cultures of Digitalis lanata by enzyme-linked immunosorbent assay.

A competitive ELISA technique using digoxin-specific antibody has been developed to determine digoxin and its related compounds in hairy root cultures of Digitalis lanata. The ELISA could detect 0.2-2 nM digoxin and closely related cardenolides. Hairy roots cultured in the dark accumulated very small amounts of cardenolides (0.02-0.07 micrograms/g dry wt), while the content of cardenolides in green hairy roots cultured in the light was increased maximally 600-fold (16.5 micrograms/g dry wt) compared to those in the dark.

Antibodies, Monoclonal↗
PubMed1996

Cytotoxic cardenolides from woods of Euonymus alata.

Three cytotoxic cardenolides, acovenosigenin A 3-O-alpha-L-ramnopyranoside (1), euonymoside A (2) and euonymusoside A (3), were isolated from the woods of Euonymus alata (Celastraceae). The chemical structure of a new cardenolide, euonymusoside A (3) has been elucidated on the basis of extensive spectral analysis and enzymic hydrolysis to be acovenosigenin A (1 beta, 3 beta, 14 beta-trihydroxy-5 beta-cardenolide) 3-O-beta-D-glucopyranosyl (1-->6)-beta-D-glucopyranosyl(1-->4)-alpha-L-rhamnopyranoside. All three showed potent cytotoxic activity against some neoplastic cell lines.

Animals↗
PubMed1980

An extension of pA principle to the potentiation of drug effects, and its application to the biological assay of some anticholinesterases and cardenolides.

A new scale for the potentiation was introduced and was termed pA1/2. The value can be calculated by using an equation; (Formula: see text), which is similar to that which is used for the calculation of pA2. For the use of the equation, the parallel shift of the dose-response curve and the unchanged maximum response are prerequisites. This experiment showed the validity and the usefulness of calculating the pA1/2 values, in the biological assay. In the assay of anticholinesterases, the potentiating effects of neostigmine or physostigmine on the acetylcholine-induced contraction were examined, by using frog's rectus abdominis. The pA1/2 values obtained in the presence of two different concentrations of anticholinesterases were the same, indicating that pA1/2 is a parameter which is specific to the potentiator. The potentiating effects of some cardenolides on the K-induced contracture were examined, by using the frog's ventricular muscles. The relative potencies of four cardenolides obtained from the pA1/2 values well agreed with those reported earlier. The amount of the cardenolides required for this assay was smaller than required for other methods.

Animals↗
PubMed1978

[Lipophilicity and enteral absorption of cardenolides (author's transl)].

Intestinal absorption of 15 cardenolides has been examined in cats. The 3H-labelled substances were injected intraluminally into ligated duodenal loops of anaesthetized animals. 3H-Concentrations were followed in the portal circulation and in the bile. 1 h after drug administration the duodenal sac was removed, and the residual in the lumen then was washed out and assayed radiochemically. The decrease of radioactivity during 1 h was calculated as extent of absorption (QR). Cardenolide absorption was compared with the corresponding in vitro parameters of lipophilicity like octanol/water partition coefficients and Rm values from reversed phase thin-layer chromatography. The Spearman rank sum correlation test revealed coefficients of 0.95 to 0.97. The result lends support to the use of the easily available Rm values as a good tool to predict intestinal absorption of various cardenolides.

Animals↗
PubMed1978

[Lipophilicity-protein binding relationship in cardenolides (author's transl)].

By equilibrium dialysis the binding of 19 cardenolides and cardenolide conjugates to human plasma proteins has been measured. The binding constants were compared with octanol-water partition coefficients described previously. No correlation was found between the two properties. Glycosides and conjugates of a certain genine show the same extent of protein binding, even if some of the derivatives differ in their physicochemical properties more than by three log units. It is concluded that cardenolide protein binding depends solely on hydrophobic property of the genine involved.

Blood Proteins↗
PubMed1975

Behaviour of cardiac glycosides and cardenolides related to digitoxigenin on sephadex LH-20.

The behaviour of six cardenolides and eight cardiac glycosides related to digitoxigenin during column chromatography on Sephadex LH-20 gel has been investigated. Complete resolution was obtained for mixtures of digitoxigenin, gitoxigenin and digoxigenin, but not for those of the 3-epimeric cardenolides. It was possible to achieve a group separation of cardenolides and their glycosides of the digitoxigenin series from those of the digoxigenin or gitoxigenin series.

Cardanolides↗