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Hydroxylysine glycosides: preparation and analysis by reverse phase high performance liquid chromatography.

Hydroxylysine diglycoside was prepared from hydrolyzed sponge by a combination of ion-exchange chromatography and gel filtration. The product obtained was chemically pure on amino acid analyzer and was active as substrate of the enzyme alpha-(1----2)glucosidase. Hyl monoglycoside was prepared by mild acid hydrolysis from diglycoside. A reverse phase HPLC system was devised for Hyl glycosides, hydroxylysine and other basic amino acids. The separation was achieved using an octadecyl bonded silica column on the compounds derivatized with dabsyl chloride to produce di-dabsyl derivatives. Elution was followed in the visible region at 436 nm. In the conditions used no or very low amount of mono-dabsyl derivatives was observed. Hyl di- and monoglycoside resulted a mixture of two diastereoisomers, which form during the alkaline hydrolysis. The separation of the diastereoisomers of each compound depended on pH and ionic strength of the eluent in the HPLC column, whereas they were not separated by our short column on amino acid analyzer. The HPLC system was also used for the analysis of Hyl glycosides on two collagen preparations.

Animals↗

Effect of cardiac glycosides on the coronaries: physiologic and morphologic studies in the dog heart.

The effect of K- strophanthoside on coronary blood flow (CBF) was studied in open chest dogs anaesthetized with pentobarbital sodium. K- strophanthoside (3.5 and 7.0 X 10(-8) mol X kg-1 i.v.) elicited a dose-dependent decrease of CBF and an increase of late diastolic coronary resistance. Intracoronary injections of the drug (1.2 X 10(-8) mol) produced selective coronary constriction. The haemodynamic pattern indicated a direct vasoconstrictor effect, independent of the extracoronary (cardiotonic) action of the drug. In the polarization microscope Romh anyi 's aldehyde bisulphite-toluidine blue (ABT) reaction as adapted for the detection of cardiac glycosides showed profuse binding of strophanthoside to the coronary vessel wall. K- strophanthoside significantly reduced the CBF increase elicited by adenosine infusion (2 X 10(-7) mol X kg-1) into the left heart. Verapamil (4 X 10(-7) mol X kg-1, i.v.), on the other hand, counteracted the strophanthoside action on CBF. The results suggest that restricted intracellular availability of Ca2+, a prerequisite of physiologic CBF increase, is opposed by cardiac glycosides.

Adenosine↗

Studies on South African cardiac glycosides. II. Observations on the clinical and haemodynamic effects of cotyledoside.

In guinea-pigs, the oral and subcutaneous LD50 values were very similar (cf. 0,173 mg/kg over 48 h with 0,116 mg/kg over 24 and 48 h). When dosed subcutaneously, a cumulative effect was observed. Intravenous administration of cotyledoside to anaesthetized guinea-pigs resulted in: dyspnoea, increased heart rates and blood pressures, and electrocardiagraphic changes typical of cardiac glycoside poisoning. A positive cardiac inotropic effect was succeeded by a positive chronotropic one. In sheep, acute and subacute intoxication resulted in ruminal, respiratory and cardiac changes. The signs included ruminal stasis, cyanosis, cardiac arrhythmia, ectopic foci and AV dissociation, followed by hypotension and progressive respiratory and cardiac failure. The skeletal muscles were affected in only 1 sheep vide infra. In chronically intoxicated sheep typical clinical signs of "krimpsiekte" developed, e.g. weakness, reluctance to stand, unsteadiness on feet, tremor and paresis of hindquarter muscles, paresis of the neck, arching of the back and standing with the feet close together. Respiratory function was affected in all 3 cases; ruminal stasis, with concomitant loss of appetite occurring in one, and a transient change in heart function in another. The syndrome induced by acute cotyledoside poisoning is similar to that of other cardiac glycosides, but the paretic signs of chronic intoxication resemble "krimpsiekte", a disease associated only with intoxication with the plants of the family Crassulaceae.

Animals↗

[Digoxin-quinidine and digoxin-amiodarone interactions. Effects on blood levels of the cardioactive glycoside].

With ever increasing frequency potentially dangerous interactions are reported between Cardiac Glycosides and other drugs, particularly the antiarrhythmic one. The AA, carried out this work with the intent of studying the possible modifications produced by Q and A on the SDL. First of all the AA. retrospectively studied the SDL of patients treated with the associations Q-D and A-D and this SDL was compared with the SDL of patients treated with D alone. Then 10 subjects treated sequentially, at first with D alone and after with the Q-D (5 p.) and A-D (5 p.) association, were studied. The results obtained confirm the data of other AA. regarding the Q-D interaction; in fact, in the presence of this antiarrhythmic drug, the SDL increase significantly following the concomitant pharmacological effects of the Cardiac Glycosides. The SDL on the contrary seem not be influenced by the A-D association. The AA. then reviewed the literature about the mechanism of the Q-D interaction. The majority of the AA. agree outlining a reduction of the Volume of Distribution and of D Clearance, in consequence of the concomitant administration of Q, which would explain the high SDL obtained. In conclusion the AA. suggest, when the Q-D association is mandatory, a 50% reduction of the D maintenance dose and to check periodically the ECG and SDL.

Adult↗

[Triterpene glycosides from Hedera taurica. XIII. Structure of taurosides St-I1 and St-I2 from Crimean ivy stems].

The taurosides, St-I1 and St-I2, isolated from the stems of Crimean ivy Hedera taurica Carr. (Araliaceae), were shown to be the known glycoside, 3-O-[beta-D-glucopyranosyl-(1-->2)-O-alpha-L-arabinopyranosyl]-28- O-[alpha-L-rhamnopyranosyl-(1-->4)-O-beta-D-glucopyranosyl-(1-->6)-O-bet a-D- glucopyranosyl]hederagenin, and a new glycoside, 3-O-[alpha-L-rhamnopyranosyl-(1-->2)-O-beta-D-glucopyranosyl]-28-O-[a lpha -L-rhamnopyranosyl-(1-->4)-O-beta-D-glucopyranosyl-(1-->6)-O-beta-D- glucopyranosyl]hederagenin, respectively.

Carbohydrate Conformation↗

[Application of non-glycoside inotropic agents in newborn infants].

Non glycoside inotropic agents are regularly used in the treatment of critically ill neonates. There are reasons to believe that the neonate reacts differently to these inotropic agents because of differences in physiology and maturation. In this paper the oxygen consumption and oxygen transport, heart failure in the newborn, effects of non glycoside inotropic agents in general and the doses of the commonly used inotropic agents (dopamine, dobutamine and isoproterenol) will be discussed. Finally a review of the literature and a therapeutic advise on the use of inotropic agents in the neonate is presented.

Cardiotonic Agents↗

Comparative pharmacokinetics and bioavailability of flavonoid glycosides of Ginkgo biloba after a single oral administration of three formulations to healthy volunteers.

Eighteen healthy volunteers received three different formulations of Ginkgo biloba: capsules (A) and drops (B) (delivered by Agon Pharma), and tablets (C) (Tebonin-Dr. W. Schwabe) in equal an quantity, orally as a single dose, at an interval of at least five days. The pharmacokinetic parameters of the most important flavonoid glycosides: quercetin, kaempferol and isorhamnetin were established. The bioavailability was estimated using capsules as a standard formulation. Only the time to reach the peak concentration (tmax) of quercetin, kaempforol and isorhamnetin administered in the form of capsules, was significantly prolonged as compared with drops and tablets. Area under the curve (AUC) was the largest for formulation B for all the evaluated flavonoid glycosides, however the differences were not statistically significant. It is concluded that the three formulations of Ginkgo biloba extract are bioequivalent.

Adolescent↗

[Effect of cardiac desympathization, stimulation of the central adrenergic structures and blockade of beta-adrenergic receptors on cardiotonic and cardiotoxic effect of cardiac glycosides].

The object of study were rabbits who had been subjected to ligation of 3 or 4 large branches of the left descending coronary artery 14-20 days before the experiment. In experiments with surgical desympathization of the heart it was established that the inotropic effect of cardiac glycosides did not depend on the concentration of catecholamines in the myocardium. In stimulation of adrenergic structures of the posterior hypothalamus attended with an increase in sympathetic innervation of the cardiovascular system the cardiotoxic threshold of cardiac glycosides was considerably reduced. Propranolol (Inderal) administered in a dose which blocks the beta-adrenergic apparatus of the heart prevents the development of the positive inotropic effect of therapeutic doses of strophanthin K on a hypodynamic left ventricular myocardium.

Animals↗

Wound healing activity of acylated iridoid glycosides from Scrophularia nodosa.

Three acylated iridoid glycosides (E)-6-O-(2", 4"-diacetyl-3" -O-p-methoxycinnamoyl)-alpha-L-rhamnopyranosyl catalpol (scopolioside A) (1), (E)-6-O-(2"-acetyl-3", 4"-di-O,O-p-methoxycinnamoyl)-alpha-L-rhamnopyranosyl catalpol (scrophuloside A(4)) (2) and (E)-6-O-(2",3"-diacetyl-4"-O-p-methoxycinnamoyl)-alpha-L-rhamnopyranosyl catalpol (scrovalentinoside) (3) have been isolated from the dried seed pods of Scrophularia nodosa by HPLC. Their structures were determined by 1D and 2D NMR, UV/Vis and mass spectroscopy and by comparison with published data. All three compounds were shown in vitro to stimulate the growth of human dermal fibroblasts. The effect was negatively dose-dependent for 2 and 3 for which fibroblast growth stimulation was highest at 0.78 microg/mL but was not significantly different from the control at 100 microg/mL. The presence of these compounds in the mature seed pods may explain the ethnobotanical use of this plant in Europe for healing wounds.

Carbohydrate Sequence↗

Mining metagenomes from extremophiles as a resource for novel glycoside hydrolases for industrial applications.

The exploration of metagenomes from extremophiles has emerged as a promising approach for discovering novel glycoside hydrolases (GHs) with potential industrial applications. Extremophiles, which thrive in harsh conditions such as high salinity, extreme temperatures, and acidic or alkaline environments, produce enzymes naturally adapted to function under these conditions. This unique adaptability makes them highly desirable for industrial processes requiring robust and efficient biocatalysts. These biocatalysts reduce reliance on harsh chemicals and energy-intensive processes, contributing to greener industrial operations. This review underscores the power of metagenomics in bypassing the need to culture large libraries of extremophiles in the lab. High-throughput sequencing and bioinformatics enable the identification of novel GH-encoding genes directly from environmental DNA. While metagenomic mining has yielded promising results, challenges such as the expression of extremophile-derived genes in mesophilic hosts, low activity yields, and scalability remain. Advances in synthetic biology and protein engineering could address these bottlenecks, enabling more efficient utilization of GHs. Additionally, integrating machine learning for predictive functional annotation may accelerate the identification of high-value candidates.

Glycoside Hydrolases↗

DNA-specific autoantibody cleaves DNA by hydrolysis of phosphodiester and glycosidic bond.

The DNA-recognizing autoantibodies were prepared in milligram scale and their catalytic activities were investigated using various standard substrates for hydrolysis of natural biomolecules such as DNA, carbohydrates, and proteins. Only phosphatase and glycosidase activity was found and no peptidase, sulfatase, or esterase activity was detected in most of anti-DNA monoclonal autoantibodies we tested. Antibody G1-2 showed the highest catalytic activities and its enzymatic characteristics were further investigated. The antibody showed phosphatase activity with sub-millimolar substrate specificity and 10(4)-10(5) rate enhancements. However, Ab G1-2 showed low micro-molar specificity with p-nitrophenyl-beta-D-N-acetylglucosamide with 10(4)-10(5) rate enhancements. Both of the catalytic activities showed pH maximum at 4-5, suggesting that the carboxylate(s) in antigen-binding site is involved in the catalytic mechanism. Chemical protection of carboxylate(s) with diazoacetamide showed much reduced activity of the Ab, confirming that the catalytic activity comes from carboxylate(s) in the Ag-binding region. The activities of phosphatase and glycosidase were thoroughly inhibited by DNA with almost identical K(i) values. These data suggest that DNA-binding site(s) is the enzymatic active site of the catalytic Abs. Capabilities of the DNA recognition might make it possible to confer the Ab the catalytic activity of phosphate and glycosidic bond hydrolysis, which can be the main cause of DNA cleavage.

Antibodies, Monoclonal↗

General synthesis and biological evaluation of alpha-1-C-substituted derivatives of fagomine (2-deoxynojirimycin-alpha-C-glycosides).

A general synthesis of alpha-1-C-substituted derivatives of fagomine (2-deoxynojirimycin-alpha-C-glycosides) by ring-opening reactions of an aziridine with various heteroatomic nucleophiles, including thiol, amine, alcohol, carboxylate and phosphate, is described. The nine-step reaction sequence proceeded in an overall yield of 14-28% from tri-O-benzyl-D-glucal. Biological evaluation of alpha-1-C-substituted derivatives of fagomine, of the 2-deoxy analog of alpha-homonojirimycin 19 and its 1,N-anhydro derivative 22 as glycosidase inhibitors is reported. The glycosyl phosphate mimetic 15k was found to display no inhibitory activity towards glycogen phosphorylase b and phosphoglucomutase.

1-Deoxynojirimycin↗

Substrate and positional specificity of feruloyl esterases for monoferuloylated and monoacetylated 4-nitrophenyl glycosides.

4-Nitrophenyl glycosides of 2-, 3-, and 5-O-(E)-feruloyl- and 2- and 5-O-acetyl-alpha-L-arabinofuranosides and of 2-, 3-, and 4-O-(E)-feruloyl- and 2-, 3- and 4-O-acetyl-beta-D-xylopyranosides, compounds mimicking natural substrates, were used to investigate substrate and positional specificity of type-A, -B, and -C feruloyl esterases. All the feruloyl esterases behave as true feruloyl esterases showing negligible activity on sugar acetates. Type-A enzymes, represented by AnFaeA from Aspergillus niger and FoFaeII from Fusarium oxysporum, are specialized for deferuloylation of primary hydroxyl groups, with a very strong preference for hydrolyzing 5-O-feruloyl-alpha-L-arabinofuranoside. On the contrary, type-B and -C feruloyl esterases, represented by FoFaeI from F. oxysporum and TsFaeC from Talaromyces stipitatus, acted on almost all ferulates with exception of 4- and 3-O-feruloyl-beta-D-xylopyranoside. 5-O-Feruloyl-alpha-L-arabinofuranoside was the best substrate for both TsFaeC and FoFaeI, although catalytic efficiency of the latter enzyme toward 2-O-feruloyl-alpha-L-arabinofuranoside was comparable. In comparison with acetates, the corresponding ferulates served as poor substrates for the carbohydrate esterase family 1 feruloyl esterase from Aspergillus oryzae. The enzyme hydrolyzed all alpha-L-arabinofuranoside and beta-D-xylopyranoside acetates. It behaved as a non-specific acetyl esterase rather than a feruloyl esterase, with a preference for 2-O-acetyl-beta-D-xylopyranoside.

Acetylation↗

Enzymatic synthesis of the glycosides of calystegines B1 and B2 and their glycosidase inhibitory activities.

Several glycosides of calystegines B1 and B2 were synthesized by use of rice alpha-glucosidase and the whole cells of Rhodotorula lactosa, and their glycosidase inhibitory activities were investigated. Incubation of mixture of calystegine B1 and maltose with rice alpha-glucosidase gave 3-O-alpha-D-glucopyranosylcalystegine B1 (2, 11.3%). An enzymatic beta-transglucosylation reaction of calystegines B1 or B2 with cellobiose using the whole cells of R. lactosa gave 3-O-beta-D-glucopyranosylcalystegine B1 (1) (0.9%) or 4-O-beta-D-glucopyranosylcalystegine B2 (3, 11.2%), respectively, while similar beta-transgalactosylation of calystegine B2 from lactose gave 4-O-beta-D-galactopyranosylcalystegine B2 (4, 10.1%). The glycosylation of calystegines B1 and B2 markedly decreased or abolished their inhibition against beta-glucosidase, alpha- or beta-galactosidase. Compound 4 however retained more or less the potency of calystegine B2 against trehalase. Interestingly, compound 1 was a noncompetitive inhibitor of rice alpha-glucosidase, with a Ki value of 0.9 +/- 0.1 microM.

Animals↗

Electrochemical detection of cyanogenic glycosides after enzymatic post-column cleavage.

Crude and partly purified extracts from Helix pomatia and linamarase from cassava were immobilized on columns packed with porous glass or silica and used as post-column reactors in the high-performance liquid chromatography of cyanogenic glycosides. Sodium hydroxide (2 M) was added to the flowstream after the enzyme-reactor resulting in the formation of cyanide, which was then detected at a silver electrode by an amperometric measurement at 0 V with reference to a silver-silver chloride electrode. The selective detection of cyanide allows measurements in a complex matrix. The response is linear and the detection limit is in the low picomole range.

Animals↗

Structure-activity relationships of synthetic digitoxigenyl glycosides.

Antiviral, cytotoxic and anti-ATPase activities of 14 synthetic digitoxigenyl glycosides were compared with each other. The activities of those containing gentiobioside and melibioside were much weaker than the others. On the other hand, the three activities were highly correlated with each other.

Adenosine Triphosphatases↗

Iridoid glycosides from Lonicera quinquelocularis.

A new iridoid glycoside 6'-O-beta-apiofuranosylsweroside was isolated from the ethanolic extract of the roots of Lonicera quinquelocularis along with the known compounds loganin and sweroside.

Disaccharides↗

Analysis of viral glycoproteins by glycosidic digestion inside a polyacrylamide gel.

We adapted the method described by Cleveland et al. (1977); (Peptide mapping by limited proteolysis in sodium dodecyl sulphate and analysis by gel electrophoresis. J. Biol. Chem. 252, 1102-1106) to study the glycosidic residues linked to the viral glycoproteins of two enveloped viruses: Junin virus (JV) and rubella virus (RV). Radioiodinated glycoproteins were obtained from purified virions, isolated from SDS-polyacrylamide gels and then hydrolysed by specific glycosidases inside a second gel. N-linked oligosaccharides, mannose and galactose were found as terminal residues in the JV-G1 glycoprotein. Mannose and N-glycans of complex hybrid type were present on RV glycoproteins.

Animals↗