Monosaccharides D-glucose Research Articles

Investigation of the Radioprotective Efficiency of Condensation Products of Thiol-Containing Hydrazides with Mono- and Disaccharides

In experiments in mice, the radioprotective efficacy of sugar-containing compounds was studied based on the condensation products of thioglycolic (TGH) and thiosalicylic (TSH) hydrazides with a series of natural aldoses: the monosaccharides D-glucose (Glс) and D-galactose (Gal) and the disaccharides D‑lactose (Lac) and D-maltose (Mal). It was shown that the use of Glc-TGH and Mal-TSH preparations increases the survival rate of deadly irradiated animals by 25% when administered 1 h before irradiation and by 40% when administered 24 h before irradiation. It is assumed that the leading role in the radioprotective activity of the drugs is played by the protection of the hematopoietic stem cells of the test animals.

Monosaccharide Isomer Interconversions Become Significant at High Temperatures.

Quantum-chemical calculations show how low barriers to anomerization and shifting equilibria cause a significant presence of different monosaccharide isomers in high-temperature processes such as pyrolysis. The transition between isomeric forms of monosaccharides is long-studied, but examination has typically been limited to the solution phase and to pyranose isomers. Processes and rates of anomerization by reversible, gas-phase ring-opening and -closing reactions were predicted for the monosaccharides d-glucose, d-mannose, d-galactose, d-xylose, l-arabinose, and d-glucuronic acid. Structures and thermochemistry were computed for stable species and pericyclic transition states using CBS-QB3, and high-pressure-limit Arrhenius reaction parameters were predicted and fitted from 300 to 1000 K. Activation energies for the ring-opening reactions were 162-217 kJ/mol for four-center pericyclic separation of the lactol group but were reduced by catalytic participation of a hydroxyl group within the monosaccharide or an external R-OH group represented by an explicit water molecule, reaching activation energies as low as 97 and 67 kJ/mol, respectively. Equilibrium constants implied increasing fractions of furanose and linear aldehyde anomers with increasing temperature.

The Sweetener-Sensing Mechanisms of the Ghrelin Cell.

Carbohydrate administration decreases plasma levels of the ‘hunger hormone’ ghrelin. The ghrelin cell is co-localized with the sweet taste receptor subunit, TAS1R3, and the gustatory G-protein, gustducin, both involved in the sensing of sweeteners by entero-endocrine cells. This study investigated the role of gustducin-mediated sweet taste receptor signaling on ghrelin secretion in a gastric ghrelinoma cell line, tissue segments and mice. The monosaccharide d-glucose and low-intensity sweetener oligofructose (OFS) decreased (p < 0.001) ghrelin secretion while the high-intensity sweetener sucralose increased (p < 0.001) ghrelin secretion in vitro. These effects were not mediated via the sweet taste receptor or glucose transporters (the sodium-dependent glucose cotransporter SGLT-1 and GLUT2). The effect of these compounds was mimicked ex vivo in gastric and jejunal segments from both wild type (WT) and α-gustducin knockout (α-gust−/−) mice. In vivo, the sensing of d-glucose was polarized since intragastric but not intravenous administration of d-glucose decreased (p < 0.05) ghrelin levels in an α-gustducin independent manner which involved inhibition of duodenal ghrelin release. In contrast, neither OFS nor sucralose affected ghrelin secretion in vivo. In conclusion, α-gustducin-mediated sweet taste receptor signaling does not play a functional role in the sensing of carbohydrates, or low- or high-intensity sweeteners by the ghrelin cell.

EPR and DFT analysis of biologically relevant chromium(V) complexes with d-glucitol and d-glucose

1,2-diolato ligands, such as carbohydrates and glycoproteins, tend to stabilize chromium(V), thus forming important intermediates that have been implicated in the genotoxicity of Cr(VI). Since many years, room-temperature continuous-wave electron paramagnetic resonance (EPR) at X-band microwave frequencies has been used as a standard characterization tool to study chromium(V) intermediates formed during the reduction of Cr(VI) in the presence of biomolecules. In this work, the added value is tested of using a combination of pulsed and high-field EPR techniques with density functional theory computations to unravel the nature of Cr(V) complexes with biologically relevant chelators, such as carbohydrates. The study focuses on the oxidochromium(V) complexes formed during reduction of potassium dichromate with glutathione in the presence of the monosaccharide d-glucose or the polyalcohol d-glucitol. It is shown that although the presence of a multitude of Cr(V) intermediates may hamper a complete structural determination, the combined EPR and DFT approach reveals unambiguously the effect of freezing on the location of the counterions, the gradual replacement of water ligands by the diols, and the preference of Cr(V) to bind certain conformers.

Preparation of S-glycoside surfactants and cysteine thioglycosides using minimally competent Lewis acid catalysis

Here we report a method for the preparation of anomerically pure β-S-glycopyranosides (1,2-trans-glycosides) from the corresponding peracetate donors. S-glycosylation was performed in CHCl3 at reflux in the presence of a catalytic amount of InBr3. Deacylation of the intermediate peracetates were achieved under Zemplén conditions. Five pyranose examples, monosaccharides D-glucose and D-galactose and disaccharides cellobiose, maltose, and lactose, were used as donors, and five thiols including an α/ω dithiol and Fmoc-L-cysteine were used as acceptors. Melting points, high res MS, [α]D and NMR data (1H and 13C, including COSY, HSQC and HMBC) are reported for compounds not previously described.

Citric acid-based deep eutectic solvents: Physical properties and their use as cosolvents in sulphuric acid-catalysed ethanolysis of oleic acid

Deep eutectic solvents (DESs) are noted to be green ionic liquid (IL) analogues, and their many favourable properties made them interesting for the scientific community. In this study, two novel DESs of citric acid with the monosaccharides D-glucose or D-fructose (1:1 molar ratio) were prepared and characterized. At the atmospheric pressure, the density, the dynamic viscosity, and the electrical conductivity of these eutectic solvents were measured and analysed as the function of temperature in the practical temperature range of 293.15-363.15 K. Arrhenius theory was employed for understanding the transport phenomena in these DESs. By using the experimental data, some important properties were calculated such as molecular volume, lattice energy, heat capacity, molar Gibbs energy, enthalpy and entropy of activation of viscous flow for the synthesized DESs. The fractional Walden rule was employed to establish the relationship between molar conductivity and viscosity, which proved an excellent linear behaviour. Finally, these DESs were tested as cosolvents in oleic acid (OA) ethanolysis. The investigated DESs possess many desirable properties, such as low vapour pressure, inflammability, biodegradability, and can be obtained from available renewable resources. These DESs showed to have the potential to be utilized for several industrial applications, like processing and separation of food constituents, pharmaceutical applications, and mediums for chemical reactions.

Design, synthesis and bioactivity of N-glycosyl-N'-(5-substituted phenyl-2-furoyl) hydrazide derivatives.

Condensation products of 5-substituted phenyl-2-furoyl hydrazide with different monosaccharides d-glucose, d-galactose,d-mannose, d-fucose and d-arabinose were prepared. The anomerization and cyclic-acyclic isomers were investigated by 1H NMR spectroscopy. The results showed that, except for the d-glucose derivatives, which were in the presence of β-anomeric forms, all derivatives were in an acyclic Schiff base form. Their antifungal and antitumor activities were studied. The bioassay results indicated that some title compounds showed superior effects over the commercial positive controls.

Transcriptional comparison of the filamentous fungus Neurospora crassagrowing on three major monosaccharides D-glucose, D-xylose and L-arabinose

BackgroundD-glucose, D-xylose and L-arabinose are the three major monosaccharides in plant cell walls. Complete utilization of all three sugars is still a bottleneck for second-generation cellulolytic bioethanol production, especially for L-arabinose. However, little is known about gene expression profiles during L-arabinose utilization in fungi and a comparison of the genome-wide fungal response to these three major monosaccharides has not yet been reported.ResultsUsing next-generation sequencing technology, we have analyzed the transcriptome of N. crassa grown on L-arabinose versus D-xylose, with D-glucose as the reference. We found that the gene expression profiles on L-arabinose were dramatically different from those on D-xylose. It appears that L-arabinose can rewire the fungal cell metabolic pathway widely and provoke the expression of many kinds of sugar transporters, hemicellulase genes and transcription factors. In contrast, many fewer genes, mainly related to the pentose metabolic pathway, were upregulated on D-xylose. The rewired metabolic response to L-arabinose was significantly different and wider than that under no carbon conditions, although the carbon starvation response was initiated on L-arabinose. Three novel sugar transporters were identified and characterized for their substrates here, including one glucose transporter GLT-1 (NCU01633) and two novel pentose transporters, XAT-1 (NCU01132), XYT-1 (NCU05627). One transcription factor associated with the regulation of hemicellulase genes, HCR-1 (NCU05064) was also characterized in the present study.ConclusionsWe conducted the first transcriptome analysis of Neurospora crassa grown on L-arabinose and performed a comparative analysis with cells grown on D-xylose and D-glucose, which deepens the understanding of the utilization of L-arabinose and D-xylose in filamentous fungi. The dataset generated by this research will be useful for mining target genes for D-xylose and L-arabinose utilization engineering and the novel sugar transportes identified are good targets for pentose untilization and biofuels production. Moreover, hemicellulase production by fungi could be improved by modifying the hemicellulase regulator discovered here.

Spectroscopic investigation of new water soluble [formula omitted] and [formula omitted] complexes for the substrate binding models of xylose/glucose isomerases

In methanol, the reaction of stoichiometric amounts of Mn(OAc)2·4H2O and the ligand H3hpnbpda [H3hpnbpda=N,N′-bis(2-pyridylmethyl)-2-hydroxy-1,3-propanediamine-N,N′-diacetic acid] in the presence of NaOH, afforded a new water soluble dinuclear manganese(II) complex, [Mn2(hpnbpda)(μ-OAc)] (1). Similarly, the reaction of Mg(OAc)2·4H2O and the ligand H3hpnbpda in the presence of NaOH, in methanol, yielded a new water soluble dinuclear magnesium(II) complex, [Mg2(hpnbpda)(μ-OAc)(H2O)2] (2). DFT calculations have been performed for the structural optimization of complexes 1 and 2. The DFT optimized structure of complex 1 shows that two manganese(II) centers are in a distorted square pyramidal geometry, whereas the DFT optimized structure of complex 2 reveals that two magnesium(II) centers adopt a six-coordinate distorted octahedral geometry. To understand the mode of substrate binding and the mechanistic details of the active site metals in xylose/glucose isomerases (XGI), we have investigated the binding interactions of biologically important monosaccharides d-glucose and d-xylose with complexes 1 and 2, in aqueous alkaline solution by a combined approach of FTIR, UV–vis, fluorescence, and 13C NMR spectroscopic techniques. Fluorescence spectra show the binding-induced gradual decrease in emission of complexes 1 and 2 accompanied by a significant blue shift upon increasing the concentration of sugar substrates. The binding modes of d-glucose and d-xylose with complex 2 are indicated by their characteristic coordination induced shift (CIS) values in 13C NMR spectra for C1 and C2 carbon atoms.

Electrochemical Detection of Sugar-related Compounds Using Boron-doped Diamond Electrodes

Electrochemical detection of sugar-related compounds was conducted using a boron-doped diamond (BDD) electrode as a detector for flow-injection analysis (FIA). Sugar-related compounds oxidize at high applied potentials, for which the BDD electrode is suitable for electrochemical measurements. Conditions for an FIA system with a BDD detector were optimized, and the following detection limits were achieved for sugar-related compounds: monosaccharides, 25-100 pmol; sugar alcohols, 10 pmol; and oligosaccharides, 10 pmol. The detection limit for monosaccharide D-glucose (Glu) was 105 pmol (S/N = 3). A linear range was acquired from the detection limit to 50 nmol, and the relative standard deviation was 0.65% (20 nmol, n = 6). A high-performance liquid chromatography (HPLC) column was added to the system between the sample injector and the detector and detection limits to the picomole level were achieved, which is the same for the HPLC system and the FIA system. The electrochemical oxidation reaction of Glu was examined using cyclic voltammetry with the BDD detector. The reaction proved to be irreversible, and proceeded according to the following two-step mechanism: (1) application of a high potential (2.00 V vs. Ag/AgCl) to the electrode causes water to electrolyze on the electrode surface with the simultaneous generation of a hydroxyl radical on the surface, and (2) the hydroxyl radical indirectly oxidizes Glu. Thus, Glu can be detected by an increase in the oxidation current caused by reactions with hydroxy radicals.

Novel Olefin-Phosphorus Hybrid and Diene Ligands Derived from Carbohydrates

Starting from readily available monosaccharides D-glucose and D-arabinose, a family of novel chiral diene and olefinphosphinite hybrid ligands has been designed. These ligands were prepared by attaching phosphinite or allylic donor sites onto unsaturated carbohydrate scaffolds. In rhodium(I)-catalysed conjugate addition ofboronic acids to enones, the olefin-phosphinite hybrids gave products in up to 99% ee and above, whereas the dienes only led to modest enantioselectivity. However, by shifting the allylic donor sites from position 4 of the pyranose to the anomeric centre, an unexpected reversal of the stereoinduction process was observed.

Synthesis of new N-aminoglycosides based on halo-substituted p-phenylenediamines and p-aminophenols

Condensation of the monosaccharides D-glucose and D-galactose with synthesized halo-substituted p-phenylenediamines and 4-amino-2,6-dibromophenol was studied. It was found that glycosylation occurred only at the 4-amino group that was sterically unhindered by the halogen atom. The position of the aglycon in the glycoside was established by PMR spectroscopy.

Synthesis of N-aminoglycosides of the alkaloid cytisine

A series of new N-aminoglycosides of the alkaloid cytisine based on industrially available monosaccharides D-glucose, D-galactose, D-xylose, and L-arabinose was synthesized and characterized. The optimal methods for condensing and isolating the products were found. The structures and position of cytisine in the glycosides were proved by PMR spectroscopy.

Bicyclic carbohydrate-derived scaffolds for combinatorial libraries

A bicyclic scaffold derived from the natural monosaccharide d-glucose, and possessing several diversity sites, was linked to various resins through the primary (C-6) hydroxyl and decorated on the solid phase: the hydroxyl group at C-4 was functionalized as ester, ether, and carbamate, the amino group in the second cycle (C-3′ position) was functionalized as amide, sulfonamide, and ureido- and thioureido-derivatives. The compounds synthesized on the solid phase were tested for their antiproliferative activity on tumor cell lines.

Further evidence for the gelation ability–structure correlation in sugar-based gelators

Eight methyl glycosides of 4,6- O-benzylidene derivatives of the monosaccharides d-glucose, d-mannose, d-allose and d-altrose were synthesized to systematically study the effect of small configurational changes on the ability to gelate organic solvents. Among the β anomers, only the d-mannose glycoside exhibits a strong gelation ability, whereas in the α-series the d-glucose and d-mannose derivatives act as versatile gelators. Also, as a general rule we found that the β anomers possess a higher ability to gelate solvents than the α anomers. The gelation properties are discussed on the basis of SAXS, FTIR, differential scanning calorimetric (DSC) measurements and scanning electron microscopy (SEM) observations. The temperature-dependent SAXS measurements were carried out to elucidate the sol–gel transition temperature. The present study emphasizes that the saccharide family provides, not only valuable information of the structural requirements for the design of new gelators, but also for molecular assembly systems in general.

Carbon and nitrogen utilization and acid production by mycelia of the ectomycorrhizal fungus Tricholoma bakamatsutake in vitro

Mycelial growth of an isolate of T. bakamatsutake was tested in media with C/N ratio ranging from 0 to 50 and with 32 carbon and 12 nitrogen sources. The isolate grew best at the C/N ratio of 30. It utilized the monosaccharides d-glucose, d-mannose, and d-fructose, the disaccharide trehalose, and polysaccharide pectin among the carbon sources; and yeast extract, l-glutamic acid, and ammonium compounds among the nitrogen sources. The growth of ten isolates and secretion of gluconic and oxalic acids were compared in d-glucose, trehalose, and pectin media. The utilization of d-glucose, trehalose, and pectin differed among the ten isolates, but all the isolates secreted gluconic acid in the d-glucose media and oxalic acid in the pectin media.

Synthesis and characterization of oxovanadium(IV) complexes with saccharides

Oxovanadium(IV) complexes of the monosaccharides d-glucose and d- fructose, and the disaccharides sucrose and turanose, were obtained in aqueous solution at pH 12. Their solid sodium salts were precipitated with absolute ethanol and characterized by UV-VIS, IR, and diffuse reflectance spectroscopies. Magnetic susceptibilities at room temperature were also determined. The L:M stoichiometry, as derived from spectrophotometric titrations, was 2:1 for all saccharides except for the d-fructose complex, which was 3:1. The analytical and magnetic data also show that in the solid state the complex of this ligand shows a different behavior, generating a dinuclear species bridged by a sugar molecule, whereas all the other complexes are mononuclear.

Automated docking of monosaccharide substrates and analogues and methyl alpha-acarviosinide in the glucoamylase active site.

Glucoamylase is an important industrial glucohydrolase with a large specificity range. To investigate its interaction with the monosaccharides D-glucose, D-mannose, and D-galactose and with the substrate analogues 1-deoxynojirimycin, D-glucono-1,5-lactone, and methyl alpha-acarviosinide, MM3(92)-optimized structures were docked into its active site using AutoDock 2.1. The results were compared to structures of glucoamylase complexes obtained by protein crystallography. Charged forms of some substrate analogues were also docked to assess the degree of protonation possessed by glucoamylase inhibitors. Many forms of methyl alpha-acarviosinide were conformationally mapped by using MM3(92), characterizing the conformational pH dependence found for the acarbose family of glucosidase inhibitors. Their significant conformers, representing the most common states of the inhibitor, were used as initial structures for docking. This constitutes a new approach for the exploration of binding modes of carbohydrate chains. Docking results differ slightly from x-ray crystallographic data, the difference being of the order of the crystallographic error. The estimated energetic interactions, even though agreeing in some cases with experimental binding kinetics, are only qualitative due to the large approximations made by AutoDock force field.

Influence of monosaccharides and related molecules on the morphology of hydroxyapatite

The influence of monosaccharides and related molecules on the crystal morphology of hydroxyapatite (HAP) precipitated from chloride-containing supersaturated solutions has been studied by transmission electron microscopy. Pulse addition of aliquots of CaCl 2 to Na 2HPO 4 solutions resulted in the formation of plate-like HAP crystals. In contrast, the presence of the monosaccharides D-glucose, D-galactose, D-mannose, glucuronic acid, N-acetyl glucosamine and D-fructose (phosphate:additive = 6:1) induced the precipitation of needle-shaped HAP crystals elongated along the c-axis. Other molecules, such as sorbitol and 1,2-butanediol, also showed this morphological effect. The order of decreasing aspect ratios was; sorbitol = 1,2-butanediol (25:1)> fructose (20:1)> glucose = galactose = mannose = glucuronic acid = N-acetyl glucosamine (10:1). Expression of the needle-like morphology is discussed in terms of kinetic factors involving nucleation and growth. The former is dependent on the exclusion of Cl - from HAP nuclei due to additive interactions with an amorphous calcium phosphate precursor phase. The latter is related to the strength of additive binding with the subsequent development of {100} HAP crystal faces.

The active transport of monosaccharides by the yeast Metschnikowia reukaufii: Evidence for an electrochemical gradient of H + across the cell membrane

The facultative anaerobic yeast Metschnikowia reukaufii was found to take up the monosaccharides d-glucose, d-xylose, and 3- O-methyl- d-glucose by a constitutive mobile membrane carrier. The uptake was dependent on the supply of metabolic energy. The half-saturation constants of transport, K T , amounted to 0.9, 2.0, and 1.0 m m, respectively. Cell suspensions of M. reukaufii catabolized d-glucose and d-xylose, but not 3- O-methyl- d-glucose. d-Xylose was accumulated about 100-fold above the diffusion equilibrium in spite of its catabolism. 3- O-Methyl- d-glucose was accumulated about 40-fold. There was no accumulation of monosaccharides in the presence of uncouplers like carbonylcyanide m-chlorophenylhydrazone or dinitrophenol. For d-glucose utilization, its transport was the ratelimiting step. All three monosaccharides were transported by the same carrier; in a mixture they competed for the binding site at the carrier. An electrochemical gradient of H + ions was measured across the plasma membrane of M. reukaufii cells. The pH difference between the cell interior and the medium of an unbuffered suspension (pH 4–5) reached the value of 2.0 pH units (inside alkaline). The membrane potential measured with the lipid-soluble cation tetraphenylphosphonium at pH 9.0 was about - 100 mV (inside negative). The onset of sugar transport brought about a short alkalinization of unbuffered cell suspensions or a depolarization of the membrane potential in buffered suspensions (pH 9.0). The H +/sugar stoichiometry was one H + ion per each sugar molecule taken up. The data are interpreted as evidence in favor of the active monosaccharide transport in M. reukaufii being an H + symport, energized by the electrochemical gradient of H + across the plasma membrane.