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Carbohydrate Research

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ISSN (Print) 0008-6215 - ISSN (Online) 0008-6215
Published by Elsevier

[2565 journals]

Structural studies of the cell wall polysaccharides from three strains of Lactobacillus helveticus with different autolytic properties: DPC4571, BROI and LH1
- Abstract: Publication date: Available online 12 June 2013
  Source:Carbohydrate Research
  Author(s): Evgeny Vinogradov , Florence Valence , Emmanuel Maes , Iva Jebava , Victoria Chuat , Sylvie Lortal , Thierry Grard , Yann Guerardel , Irina Sadovskaya
  Lactobacillus helveticus is traditionally used in dairy industry as a starter or an adjunct culture for manufacture of cheese and some types of fermented milk. Its autolysis releases intracellular enzymes is a prerequisite for optimum cheese maturation, and is known to be strain dependant. Autolysis is caused by an enzymatic hydrolysis of the cell wall peptidoglycan (PG) by endogenous peptidoglycan hydrolases (PGHs) or autolysins. Origins of differences in autolytic properties of different strains are not fully elucidated. Regulation of autolysis possibly depends on the structure of the cell wall components other than PG, particularly polysaccharides. In the present work, we screened six L. helveticus strains with different autolytic properties: DPC4571, BROI and LH1. We established, for the first time, that cell walls (CWs) of these strains contained polysaccharides, different from their CW teichoic acids. Cell wall polysaccharides of three strains were purified, and their chemical structures were established by 2D NMR spectroscopy and methylation analysis. The structures of their repeating units are presented.
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  PubDate: 2013-06-15T23:06:55Z
Production of chitooligosaccharides from Rhizopus oligosporus NRRL2710 cells by chitosanase digestion
- Abstract: Publication date: Available online 13 June 2013
  Source:Carbohydrate Research
  Author(s): Maria Mahata , Shoko Shinya , Eiko Masaki , Takashi Yamamoto , Takayuki Ohnuma , Ryszard Brzezinski , Tapan K. Mazumder , Kazuhiko Yamashita , Kazue Narihiro , Tamo Fukamizo
  The intact cells of Rhizopus oligosporus NRRL2710, whose cell walls are abundant source of N-acetylglucosamine (GlcNAc) and glucosamine (GlcN), were digested with three chitinolytic enzymes, a GH-46 chitosanase from Streptomyces sp. N174 (CsnN174), a chitinase from Pyrococcus furiosus, and a chitinase from Trichoderma viride, respectively. Solubilization of the intact cells by CsnN174 was found to be the most efficient from solid state CP/MAS 13C-NMR spectroscopy. Chitosanase products from Rhizopus cells were purified by cation exchange chromatography on CM-Sephadex C-25 and gel-filtration on Cellulofine Gcl-25m. NMR and MALDI-TOF-MS analyses of the purified products revealed that GlcN-GlcNAc, (GlcN)2-GlcNAc, and (GlcN)2 were produced by the enzymatic digestion of the intact cells. The chitosanase digestion of Rhizopus cells was found to be an excellent system for the conversion of fungal biomass without any environmental impact.
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  PubDate: 2013-06-15T23:06:55Z
Structure and gene cluster of the O-antigen of Escherichia coli O76
- Abstract: Publication date: 9 August 2013
  Source:Carbohydrate Research, Volume 377
  Author(s): Andrei V. Perepelov , Quan Wang , Sof’ya N. Senchenkova , Lu Feng , Alexander S. Shashkov , Lei Wang , Yuriy A. Knirel
  The O-polysaccharide (O-antigen) of Escherichia coli O76 was studied by sugar analysis along with 1D and 2D 1H,13C NMR spectroscopies. The following structure of the linear tetrasaccharide repeating unit was established: The degree of O-acetylation of 4-substituted β-GalNAc residue is ∼70%. The O-antigen gene cluster of E. coli O76 was sequenced. The functions of genes in the O-antigen gene cluster were tentatively assigned by comparison with sequences in the available databases and found to be in full agreement with the E. coli O76 O-antigen structure.
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  PubDate: 2013-06-15T23:06:55Z
Conformational studies of diosgenyl 2-amino-2-deoxy-β-d-glucopyranosides at the PM3 and DFT levels of theory
- Abstract: Publication date: 9 August 2013
  Source:Carbohydrate Research, Volume 377
  Author(s): Andrzej Nowacki , Henryk Myszka , Beata Liberek
  Geometry optimizations at the PM3 level were performed for diosgenyl 2-amino-2-deoxy-β-d-glucopyranoside and its N-protonated form. Next, B3LYP/6-311++G∗∗ level geometry optimizations were carried out, albeit on a simpler model. The relative Gibbs free energies and geometry parameters are presented for the optimized structures. Conformational analysis concerning the clockwise (cw) and counterclockwise (ccw) arrangements of the OH groups as well as the three orientations of the NH2 and CH2OH groups was performed. Furthermore, a full scan of all the possible locations of the diosgenyl moiety in relation to the sugar ring in the target compounds was done. The PM3 optimization results indicate that diosgenyl 2-amino-2-deoxy-β-d-glucopyranoside exists as a mixture of many rotamers. Of these, ccw conformers as well as the −ac orientation of the aglycone (ca −100° for torsion angle ϕ) are preferred. In the case of the N-protonated glucoside one rotamer is dominant in the mixture (population>60%). Only the cw arrangement is stable in the protonated form, because of steric and electronic repulsion between the charged ammonium group and the hydrogen atom of the neighbouring 3-OH group. The gauche-trans (gt) orientation of the CH2OH group is favourable to both neutral and protonated forms of diosgenyl glucosides at the PM3 level. DFT studies also predict conformational mixtures for both neutral and protonated forms of simplified diosgenyl 2-amino-2-deoxy-β-d-glucopyranosides. These investigations showed unequivocally the preference for the ccw arrangement over cw, and that values of angle ϕ concur with the exo-anomeric effect. The B3LYP functional predicts the greater stability of the gt and tg orientations for the neutral and protonated analogues respectively. According to both PM3 and B3LYP calculations, torsion angle ψ has only a minor influence on the conformational energy. The importance of the geometry parameters affecting the stability of these conformers appears to be as follows: angle ϕ ≈NH2/ccw/cw> gg/gt/tg >angle ψ.
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  PubDate: 2013-06-15T23:06:55Z
Optimizing the selectivity of DIFO-based reagents for intracellular bioorthogonal applications
- Abstract: Publication date: 9 August 2013
  Source:Carbohydrate Research, Volume 377
  Author(s): Eun J. Kim , Dong W. Kang , Hans F. Leucke , Michelle R. Bond , Salil Ghosh , Dona C. Love , Jong-Seog Ahn , Dae-Ook Kang , John A. Hanover
  One of the most commonly employed bioorthogonal reactions with azides is copper-catalyzed azide–alkyne [3+2] cycloaddition (CuAAC, a ‘click’ reaction). More recently, the strain-promoted azide–alkyne [3+2] cycloaddition (SPAAC, a copper-free ‘click’ reaction) was developed, in which an alkyne is sufficiently strained to promote rapid cycloaddition with an azide to form a stable triazole conjugate. In this report, we show that an internal alkyne in a strained ring system with two electron-withdrawing fluorine atoms adjacent to the carbon–carbon triple bond reacts to yield covalent adducts not only with azide moieties but also reacts with free sulfhydryl groups abundant in the cytosol. We have identified conditions that allow the enhanced reactivity to be tolerated when using such conformationally strained reagents to enhance reaction rates and selectivity for bioorthogonal applications such as O-GlcNAc detection.
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  PubDate: 2013-06-15T23:06:55Z
Stability of aminooxy glycosides to glycosidase catalysed hydrolysis
- Abstract: Publication date: 9 August 2013
  Source:Carbohydrate Research, Volume 377
  Author(s): Amjid Iqbal , Hicham Chibli , Chris J. Hamilton
  The stability of the amino(methoxy) beta-glycosidic bond to glycosidase catalysed hydrolysis is reported. Beta-O-benzyl glucose and beta-O-benzyl galactose are substrates hydrolysed by beta-glucosidase and beta-galactosidase from almonds and Escherichia coli, respectively. However their beta-N-benzyl-(O-methoxy)-glucoside and beta-N-benzyl-(O-methoxy)-galactoside derivatives are competitive inhibitors.
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  PubDate: 2013-06-11T23:06:04Z
Ionic Liquid Crystals as Alignment Medium to Measure Residual Dipolar Couplings for Carbohydrates
- Abstract: Publication date: Available online 9 June 2013
  Source:Carbohydrate Research
  Author(s): Murali Dama , Stefan Berger
  Ionic Liquids consisting of N-dodecyl-N-methyl pyrrolidinium bromide [C12MPB] in a mixture with D2O, decanol and DMSO were for the first time found to give anisotropic molecular alignment in the magnetic field and are useful to measure residual dipolar couplings (RDCs) from polar analytes e.g. glucose. The system shows less quadrupolar splitting of the deuterated solvent signal compared with other liquid crystal systems and hence less undesired line broadening.
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  PubDate: 2013-06-11T23:06:04Z
Preliminary investigation of a highly sulfated galactofucan fraction isolated from the brown alga Sargassum polycystum
- Abstract: Publication date: Available online 9 June 2013
  Source:Carbohydrate Research
  Author(s): Maria I. Bilan , Alexey A. Grachev , Alexander S. Shashkov , Thanh Thi Thu Thuy , Tran Thi Thanh Van , Bui Minh Ly , Nikolay E. Nifantiev , Anatolii I. Usov
  A fucoidan preparation was isolated from the brown alga Sargassum polycystum (Fucales, Sargassaceae). The preparation was fractionated by anion-exchange chromatography, and two highly sulfated fractions F3 and F4 were obtained. The fractions were quite similar in composition, but different in chemical structure. F4 was analyzed by chemical methods, including desulfation, methylation, Smith degradation, and partial acid hydrolysis with mass-spectrometric monitoring, as well as by NMR spectroscopy. Several 2D NMR procedures, including HMQC-TOCSY and HMQC-NOESY, were used to obtain reliable structural information from the complex spectra. Molecules of F4 were shown to contain a backbone built up mainly of 3-linked α-l-fucopyranose 4-sulfate residues, as in many other fucoidans, but rather short sequences of these residues are interspersed by single 2-linked α-d-galactopyranose residues also sulfated at position 4. This rather unusual structural feature should have a great influence on the conformation of polymeric molecule and may be important for biological activity of the polysaccharide. Hence, F4 is an example of a new sulfated galactofucan isolated from the brown alga. According to the data obtained, the distribution of galactose residues along the polysaccharide backbone seems to be not strictly regular, but the definitive sequence of monomers in the polymeric molecules awaits additional investigation.
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  PubDate: 2013-06-11T23:06:04Z
A reinvestigation of the synthesis and revision of spectral data of 1,2-O-isopropylidene-α-l-sorbofuranose, 1,2:4,6-di-O-isopropylidene-α-l-sorbofuranose and derivatives
- Abstract: Publication date: Available online 11 June 2013
  Source:Carbohydrate Research
  Author(s): Anna Biela-Banas , Estelle Gallienne , Olivier R. Martin
  Mono- and di-O-isopropylidene-l-sorbofuranose derivatives are important starting materials for the synthesis of modified sugars and useful chiral compounds. However, several inconsistencies in the spectral data of these compounds and erroneous structural assignments have been noted in the literature. The unambiguous synthesis of 1,2:4,6-di-O-isopropylidene-α-l-sorbofuranose and of derivatives of 1,2- and 2,3-O-isopropylidene-α-l-sorbofuranoses has been achieved and definitive spectral data on these compounds are provided.
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  PubDate: 2013-06-11T23:06:04Z
Graphical contents list
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  
  PubDate: 2013-06-07T23:06:31Z
Editorial board
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  
  PubDate: 2013-06-07T23:06:31Z
Structural elucidation of a novel water-soluble fructan isolated from Wedelia prostrata
- Abstract: Publication date: 19 July 2013
  Source:Carbohydrate Research, Volume 376
  Author(s): An-qiang Zhang , Yang Zhang , Jun Yang , Jian Jiang , Fang-fang Huang , Pei-long Sun
  A new heteropolysaccharide, WPP60A, with a molecular weight of 2.4kDa, was isolated from Wedelia prostrata by hot water extraction, and purified by DEAE Sepharose fast flow and Sephacryl S-200 high-resolution chromatography. Compositional analysis, and methylation analysis, combined with 1H, 13C NMR spectroscopy including 2D NMR (COSY, TOCSY, HMQC, NOESY, and HMBC) experiments demonstrated that WPP60A was composed of primarily fructose and low glucose. Results indicated that this new heteropolysaccharide consists of a repeating unit with the following structure:
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  PubDate: 2013-06-07T23:06:31Z
Role of the 4,6-O-acetal in the regio- and stereoselective conversion of 2,3-di-O-sulfonyl-β-d-galactopyranosides to d-idopyranosides
- Abstract: Publication date: 19 July 2013
  Source:Carbohydrate Research, Volume 376
  Author(s): Rachel Hevey , Xining Chen , Chang-Chun Ling
  The recently reported conversion of 2,3-di-O-sulfonyl-d-galactopyranosides to d-idopyranosides has provided an efficient route to obtaining orthogonally-protected idopyranoside building blocks with a β-1,2-cis glycosidic linkage. In an effort to expand the scope of this process and better understand the regio- and stereoselectivity observed in the key di-inversion step of the method, a small library of 4,6-O-acetal protected galactopyranosides has been synthesized and used as substrates in the process, together with a number of substrates that lack the acetal functionality. The results suggest that although the substituent at the acetal center does not contribute to the observed selectivity of the process, the acetal group is indeed required for efficient conversion by reducing the conformational flexibility of the substrate, resulting in enhanced reaction rates at both the O-transsulfonylation and epoxide ring-opening steps.
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  PubDate: 2013-06-07T23:06:31Z
Modifications in the nitric acid oxidation of d-mannose: X-ray crystal structure of N,N′-dimethyl d-mannaramide
- Abstract: Publication date: 19 July 2013
  Source:Carbohydrate Research, Volume 376
  Author(s): Chrissie A. Carpenter , Kenneth I. Hardcastle , Donald E. Kiely
  Nitric acid oxidation of d-mannose was carried out under an oxygen atmosphere using a computer controlled reactor. The process represents a catalytic oxidation of d-mannose with oxygen as the terminal oxidant. The crude oxidation product was esterified with methanolic HCl and the esterified product directly converted to crystalline N,N′-dimethyl-d-mannaramide with methylamine. Treatment of the diamide in aqueous sodium hydroxide gave solid disodium d-mannarate. The X-ray crystal structure of N,N′-dimethyl-d-mannaramide was determined as a model for the repeating d-mannaramide units of stereoregular poly(alkylene-d-mannaramides). Disodium d-mannarate was prepared as a precursor of esterified d-mannaric acid for use as a reactive diacid monomer to prepare poly-d-mannaramides.
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  PubDate: 2013-06-07T23:06:31Z
Chemical synthesis of the tetrasaccharide repeating unit of the O-antigenic polysaccharide from Plesiomonas shigelloides strain AM36565
- Abstract: Publication date: 19 July 2013
  Source:Carbohydrate Research, Volume 376
  Author(s): Rituparna Das , Balaram Mukhopadhyay
  Chemical synthesis of the tetrasaccharide repeating unit of the O-antigenic polysaccharide from Plesiomonas shigelloides strain AM36565 is reported. Glycosylations between suitably protected monosaccharide synthons were achieved by the activation of thioglycosides in the presence of H2SO4–silica in conjunction with N-iodosuccinimide. The glycosylations accomplished were highly stereoselective and afforded the desired products in good to excellent yields.
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  PubDate: 2013-05-30T23:06:40Z
Synthesis of 6′-acylamido-6′-deoxy-α-d-galactoglycerolipids
- Abstract: Publication date: 19 July 2013
  Source:Carbohydrate Research, Volume 376
  Author(s): Chunxia Li , Yihua Sun , Jun Zhang , Zhimin Zhao , Guangli Yu , Huashi Guan
  Aminoglycoglycerolipid 1a isolated from an algal extract showed activity against the enzyme Myt1 kinase with an IC50 value of 0.12μg/mL. Its analogues, 6′-acylamido-6′-deoxy-α-d-galactoglycerolipids (2a–g) were synthesized in an efficient way with high stereoselectivity. The key step was to employ a 4-OAc protecting group of the galactosyl donor 14 as a remote neighboring participation group to give the glycoside with high α-anomeric selectivity (α:β =32:1) in the glycosylation. The preliminary bioactivity screening showed that compound 2g exhibited good inhibition against Myt1 kinase.
  Graphical abstract Highlights ► 6′-acylamido-6′-deoxy-α-d-galactoglycerolipids 2a–g were synthesized in a concise strategy with high stereoselectivity. ► Glycosylation employing thiogalactoside donor 14 with a 4-OAc protecting group was achieved with excellent α-selectivity. ► Compound 2g showed good inhibition against Myt1 kinase.
  
  PubDate: 2013-05-30T23:06:40Z
Propargylation of arabinogalactan with propargyl halides—a facile route to new functionalized biopolymers
- Abstract: Publication date: 19 July 2013
  Source:Carbohydrate Research, Volume 376
  Author(s): Lyudmila A. Grischenko , Lidiya N. Parshina , Lyudmila V. Kanitskaya , Lyudmila I. Larina , Lyubov N. Novikova , Boris A. Trofimov
  New arabinogalactan propargyl ethers with degree of substitution (DS) up to 2.8 have been obtained by propargylation of arabino-3,6-galactan (AG) with propargyl bromide (PB) in the two-phase system 30–60% КОН aqueous solution/toluene in the presence of triethylbenzylammonium chloride (TEBAС) or without catalyst (ambient temperature, 1–24h) in 20–87% yields. The highest yields have been reached using TEBAС as phase-transfer catalyst, though the non-catalytic version proves to be also efficient (DS 2.8, 70% yield). The propargylation of AG is less effective in the systems MОН (M=Na, K)/DMSO. DS of propargyl AG reaches 1.8 (70% yield) when propargyl chloride is used as propargylating agent, while with PB under the same conditions DS value does not exceed 0.4–0.6, the yields being 44–65%. Under the action of t-BuOK/DMSO system, the AG propargyl ethers have been isomerized to the corresponding unstable allenyl ethers. AG propargyl ethers with DS 2.0 have been almost exhaustively metallated with Ag2O/NH3 system to give AG–Ag acetylides derivatives with Ag/CC ratio equaling 0.95.
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  PubDate: 2013-05-30T23:06:40Z
Furfural degradation in a dilute acidic and saline solution in the presence of glucose
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  Author(s): B. Danon , L. van der Aa , W. de Jong
  A kinetic study has been performed on the degradation of furfural in a dilute acidic and saline solution with and without the presence of glucose. Experiments have been performed in a stirred batch reactor. The degradation of furfural alone was accurately predicted both using a first- and a second-order kinetic model. It was shown that furfural is degrading significantly faster when glucose is present in the reaction mixture. In the series with glucose present distinct second-order reaction kinetics were observed. From experiments with varying concentrations of glucose it turned out that an additional (second-order) reaction had to be added to the reaction mechanism in order to satisfactorily predict the experimental data. This additional reaction incorporated the initial glucose concentration as a constant in the Arrhenius expression for the reaction rate constant. Furthermore, it has been argued that this second-order reaction could well be a Diels–Alder reaction.
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  PubDate: 2013-05-26T23:06:18Z
Polysaccharides from the edible mushroom Calocybe gambosa: structure and chain conformation of a (1→4),(1→6)-linked glucan
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  Author(s): Ana Villares
  Three polysaccharides were isolated from the fruiting bodies of the mushroom Calocybe gambosa by cold water (PS-Cg fC), hot water (PS-Cg fH), and hot aqueous NaOH (PS-Cg fB) extractions. The size exclusion chromatograms presented in all cases a single peak showing a molecular weight of 145kDa. On the basis of acid hydrolysis, methylation analysis, and NMR analysis, the structure of the three polysaccharides appeared to be equivalent. The three carbohydrates were composed of glucose and the methylation analysis showed that the units were (1→4),(1→6)-linked with a degree of branching (DB) of 4%. NMR experiments showed that the three fractions contained the same polysaccharide. 1H NMR spectroscopy revealed that the linkages were β-type in all cases. The complexation with Congo red demonstrated that the polysaccharides displayed a triple-strand helical conformation. The polysaccharides were composed of a repeating unit with a structure as below:
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  PubDate: 2013-05-26T23:06:18Z
Chemical shift assignment of the complicated monomers comprising cellulose acetate by two-dimensional NMR spectroscopy
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  Author(s): Hiroyuki Kono
  1H and 13C chemical shift assignment of the anhydroglucose units (AGUs) that comprise cellulose acetate with the total degree of substitution of 2.33 was performed by a combination of two-dimensional NMR spectra obtained from COSY, TOCSY, HSQC–TOCSY, and HSQC experiments. In the TOCSY spectra, there are 13 kinds of correlation networks for the H1 to H6′ atoms of AGU; each 1H resonance of the 13 AGUs was assigned from the changes in the intensities of the 1H resonances with TOCSY spin-lock time during the TOCSY experiments. The ring 13C resonances were assigned via analysis of HSQC spectra. Comparison of the shift data enabled the assignment of the 13 AGUs as three types of 2,3,6-tri-acetylated, one type of 2-mono-, 3-mono-, 6-mono-, 2,3-di-, 2,6-di-, and 3,6-di-acetylated AGU, and unsubstituted AGU, and three types of AGUs located in end units. These shift data will be useful for characterizing the molecular structures of cellulose derivatives as well as cellulose acetate (CA).
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  PubDate: 2013-05-22T23:06:58Z
Parallel quantification of lectin–glycan interaction using ultrafiltration
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  Author(s): Yoichi Takeda , Akira Seko , Masafumi Sakono , Masakazu Hachisu , Akihiko Koizumi , Kohki Fujikawa , Yukishige Ito
  Using ultrafiltration membrane, a simple method for screening protein–ligand interaction was developed. The procedure comprises three steps: mixing ligand with protein, ultrafiltration of the solution, and quantification of unbound ligands by HPLC. By conducting analysis with variable protein concentrations, affinity constants were easily obtained. Multiple ligands can be analyzed simultaneously as a mixture, when concentration of ligands was controlled. Feasibility of this method for lectin–glycan interaction analysis was examined using fluorescently labeled high-mannose-type glycans and recombinant intracellular lectins or endo-α-mannosidase mutants. Estimated K a values of malectin and VIP36 were in good agreement indeed with those evaluated by conventional methods such as isothermal titration calorimetry (ITC) or frontal affinity chromatography (FAC). Finally, several mutants of endo-α-mannosidase were produced and their affinities to monoglucosylated glycans were evaluated.
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  PubDate: 2013-05-22T23:06:58Z
Synthesis of a chlorogenin glycoside library using an orthogonal protecting group strategy
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  Author(s): Ying-Hsin Wang , Hsien-Wei Yeh , Hsiao-Wen Wang , Chia-Chun Yu , Jih-Hwa Guh , Der-Zen Liu , Pi-Hui Liang
  Naturally occurring spirostanol saponins bear a chacotriose, α-l-rhamnopyranosyl-(1→2)-[α-l-rhamnopyranosyl-(1→4)]-β-d-glucopyranose residue as the oligosaccharide moiety which is believed to be important for biological activity. Herein the development of a concise, combinatorial method for the synthesis of two series of glycan variants at the 2′ and/or 4′ positions of chacotriose is described and the structure–activity relationships of the glycone part at 3-OH of chlorogenin investigated. These compounds were found to be weakly-cytotoxic toward leukemia cell lines CCRF and HL-20, indicating that the chacotriose moiety is important for anticancer activity.
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  PubDate: 2013-05-22T23:06:58Z
Structure of the O-polysaccharide of Providencia alcalifaciens O35 containing an N-[(S)-1-carboxyethyl]-l-alanine (alanopine) derivative of 4-amino-4,6-dideoxyglucose
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  Author(s): Olga G. Ovchinnikova , Olga A. Valueva , Nina A. Kocharova , Nikolay P. Arbatsky , Agnieszka Maszewska , Agnieszka Zablotni , Alexander S. Shashkov , Antoni Rozalski , Yuriy A. Knirel
  The O-polysaccharide of Providencia alcalifaciens O35 was studied by sugar and methylation analyses along with 1H and 13C NMR spectroscopy, including 2D 1H,13C HMBC, and NOESY experiments in D2O and, to detect correlations for NH protons, in a 9:1 H2O/D2O mixture. A unique N-(1-carboxyethyl)alanine (alanopine, Alo) derivative of 4-amino-4,6-dideoxyglucose (Qui4N) was identified as the polysaccharide component. Alanopine was isolated by solvolysis of the polysaccharide with triflic acid followed by acid hydrolysis, and its (2S,4S)-configuration was determined by the specific optical rotation. The following structure of the O-polysaccharide was established (the d configuration of Qui4N was ascribed tentatively):
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  PubDate: 2013-05-18T23:06:18Z
The structure of the O-specific polysaccharide from marine bacterium Litorimonas taeanensis G5T containing 2-acetamido-4-((3S,5S)-3,5-dihydroxyhexanamido)-2,4-dideoxy-d-quinovose and 2-acetamido-2,6-dideoxy-l-xylo-hexos-4-ulose
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  Author(s): Maxim S. Kokoulin , Anatoliy I. Kalinovsky , Nadezhda A. Komandrova , Victoria E. Tovarchi , Svetlana V. Tomshich , Ol’ga I. Nedashkovskaya , Victor E. Vaskovsky
  The O-polysaccharide was isolated from the lipopolysaccharide of Litorimonas taeanensis G5T and studied by chemical methods along with 1H and 13C NMR spectroscopy, including 1H, 1H COSY, 1D and 2D TOCSY, NOESY, 1H, 13C HSQC, HMBC, and H2BC experiments. The following new structure of the O-polysaccharide of L. taeanensis G5T containing 2-acetamido-2-deoxy-d-galacturonic acid (d-GalNAcA), 2-acetamido-4-((3S,5S)-3,5-dihydroxyhexanamido)-2,4-dideoxy-d-quinovose (d-QuiNAc4NR), and 2-acetamido-2,6-dideoxy-l-xylo-hexos-4-ulose (l-Sug) was established: where R is (3S,5S)-3,5-dihydroxyhexanoic acid.
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  PubDate: 2013-05-18T23:06:18Z
High molecular weight plant heteropolysaccharides stimulate fibroblasts but inhibit keratinocytes
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  Author(s): Munira Shahbuddin , Dahlia Shahbuddin , Anthony J. Bullock , Halijah Ibrahim , Stephen Rimmer , Sheila MacNeil
  Konjac glucomannan (KGM) is a natural polysaccharide of β(1-4)-d-glucomannopyranosyl backbone of d-mannose and d-glucose derived from the tuber of Amorphophallus konjac C. Koch. KGM has been reported to have a wide range of activities including wound healing. In this study we examined KGM extracts prepared from five plant species, (Amorphophallus konjac Koch, Amorphophallus oncophyllus, Amorphophallus prainii, Amorphophallus paeoniifolius and Amorphophallus elegans) for their effects on cultured human keratinocytes and fibroblasts. Extracts from A. konjac Koch, A. oncophyllus and A. prainii (but not from A. paeoniifolius or A. elegans) stimulated fibroblast proliferation both in the absence and presence of serum. However, these materials inhibited keratinocyte proliferation. The fibroblast stimulatory activity was associated with high molecular weight fractions of KGM and was lost following ethanol extraction or enzyme digestion with β-mannanase. It was also reduced by the addition of concanavalin A but not mannose suggesting that these heteropolysaccharides are acting on lectins but not via receptors specific to mannose. The most dramatic effect of KGM was seen in its ability to support fibroblasts for 3weeks under conditions of deliberate media starvation. This effect did not extend to supporting keratinocytes under conditions of media starvation but KGM did significantly help support adipose derived stem cells under media starvation conditions.
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  PubDate: 2013-05-18T23:06:18Z
Microwave-assisted rapid conversion of carbohydrates into 5-hydroxymethylfurfural by ScCl3 in ionic liquids
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  Author(s): Xuanmu Zhou , Zehui Zhang , Bing Liu , Zheng Xu , Kejian Deng
  In this study, synthesis of HMF from carbohydrates was carried out in ionic liquids 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) catalyzed by ScCl3 under microwave irradiation. Under the optimal reaction conditions, HMF was obtained in a high yield of 73.4% in 2mins with the microwave power at 400W. Compared with the conventional oil-bath heating manner, the use of microwave irradiation not only reduced reaction times from hours to minutes, but also improved HMF yield. This catalytic system could be reused several times without losing its catalytic activity. This efficient catalytic system will generate a promising application strategy for biomass transformation.
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  PubDate: 2013-05-18T23:06:18Z
Evaluation of carbohydrates and lignocellulosic biomass from different wood species as raw material for the synthesis of 5-bromomethyfurfural
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  Author(s): Aleksei Bredihhin , Uno Mäeorg , Lauri Vares
  The influence of different parameters on the conversion of carbohydrates and biomass into the potential biofuel intermediate 5-bromomethylfurfural (BMF) has been studied. Our optimized conditions avoid the use of lithium salt additives, making this method cheaper and environmentally more benign compared to previously reported methods. Different wood species and their potential as a raw material in BMF and furfural production have also been evaluated. In addition, we report a very simple and efficient procedure for conversion of 5-hydroxymethylfurfural (HMF) into BMF or 5-chloromethylfurfural (CMF).
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  PubDate: 2013-05-18T23:06:18Z
One-pot synthesis of O-glycosyl triazoles by O-glycosylation–click reaction
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  Author(s): Wadchara Mangsang , Uthaiwan Sirion , Rungnapha Saeeng
  2,3-Unsaturated-glycosyl triazoles were synthesized in a simple one-pot process under mild condition via tandem O-glycosylation using iodine promoter and a mild CuAAC reaction. Thirty examples of a variety of O-glycosyl triazoles were obtained in good to excellent yields and α-anomeric selectivity.
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  PubDate: 2013-05-18T23:06:18Z
Comparative analysis of flagellin glycans among pathovars of phytopathogenic Pseudomonas syringae
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  Author(s): Kazuhiro Chiku , Masanobu Yamamoto , Mayumi Ohnishi-Kameyama , Tadashi Ishii , Mitsuru Yoshida , Fumiko Taguchi , Yuki Ichinose , Hiroshi Ono
  Flagellin is a principal component of the flagellum filament. Previously, we reported that the flagellin of Pseudomonas syringae pv. tabaci 6605 (Pta6605) was glycosylated by oligosaccharides composed of two or three l-rhamnosyl (l-Rha) residues and a terminal 4,6-dideoxy-4-(3-hydroxybutanamide)-2-O-methylglucopyranosyl residue. In this study, we characterized the chemical structure of flagellin glycans in P. syringae pathovars glycinea race 4 (Pgl4), phaseolicola 1448A (Pph1448A), tomato DC3000 (PtoDC3000), and syringae B728a (PsyB728a). Flagellin glycans were released by hydrazinolysis, labeled on the reducing ends with 2-aminopyridine (PA), and the PA-labeled oligosaccharides were isolated by high-performance liquid chromatography. The purified PA-labeled glycans were analyzed by mass spectrometry and NMR spectroscopy. The results showed that the glycans on flagellin of Pgl4, PtoDC3000, and Pph1448A were identical to those of Pta6605, which were characterized previously. The flagellin of PsyB728a is O-glycosylated with a novel trisaccharide identified as 2-acetamide-2-deoxy-β-d-glucopyranosyl-(1→2)-3-O-methyl-α-l-rhamnopyranosyl-(1→2)-l-rhamnose. Our data indicate that flagellin glycosylation of P. syringae pathovars has universality with little diversity.
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  PubDate: 2013-05-18T23:06:18Z
N-linked glycolipids by Staudinger coupling of glycosylated alkyl diazides with fatty acids
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  Author(s): Salih Mahdi Salman , Thorsten Heidelberg , Hairul Anuar Bin Tajuddin
  Aiming for new glycolipids with enhanced chemical stability and close structural similarity to natural cell membrane lipids for the development of a drug delivery system, we have synthesized double amide analogs of glyco-glycerolipids. The synthesis applied a Staudinger reaction based coupling of a 1,3-diazide with fatty acid chlorides. While the concept furnished the desired glucosides in reasonable yields, the corresponding lactosides formed a tetrahydropyrimidine based 1:1 coupling product instead. This unexpected coupling result likely originates from steric hindrance at the iminophosphorane intermediate and provides an interesting core structure for potentially bioactive surfactants. The assembly behavior of both glycolipid types was investigated by optical polarizing microscopy, DSC and surface tension studies.
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  PubDate: 2013-05-18T23:06:18Z
Synthesis of all four stereoisomers of 5-formyl-4-hydroxymethyl-1,3-oxazolidin-2-ones from d-glucosamine
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  Author(s): Teiichi Murakami
  All four stereoisomers of 5-formyl-4-hydroxymethyl-1,3-oxazolidin-2-ones (FHOs) were conveniently prepared from d-glucosamine by base-catalyzed epimerizations. 2-N,3-O-Carbonyl-d-glucosamine (7) was successively treated with NaBH4 and NaIO4 to give (4S,5R)-FHO 18, which was epimerized with DBU in DMF to give (4S,5S)-FHO 20. The glucosamine derivative 7 was epimerized to 2-N,3-O-carbonyl-d-mannosamine 23, from which (4R,5R)- and (4R,5S)-FHO derivatives (27 and 31) were prepared. The NMR measurements revealed that the 4,5-cis-4(or 5)-formyl-5(or 4)-hydroxymethyl-oxazolidinone derivatives form five-membered lactol ring, whereas the 4,5-trans-disubstituted derivatives form the hydrate or methanol adduct of the open-chain aldehyde, or the symmetrical dimer.
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  PubDate: 2013-05-18T23:06:18Z
Recent developments of ionic liquids in oligosaccharide synthesis: the sweet side of ionic liquids
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  Author(s): M. Carmen Galan , Rachel A. Jones , Anh-Tuan Tran
  The area of ionic liquid (IL) research has seen tremendous growth over the last few decades. The development of novel ILs with new and attractive physical and chemical properties has had a direct impact on organic synthesis. In particular, ILs have had many applications in carbohydrate chemistry including their use as solvents for dissolving high molecular weight carbohydrate polymers such as cellulose and as solvents and catalysts in oligosaccharide synthesis. In this area, ILs have been involved in protecting group manipulation reactions as well as glycosidic couplings leading to new methodologies and enhanced procedures. In addition, ILs have been successfully utilized as solution-phase purification supports. This review focuses on the most recent advances in the application of ILs to oligosaccharide synthesis. This is an emerging area that offers great promise at addressing some of the obstacles that remain on the path towards the automation of oligosaccharide synthesis.
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  PubDate: 2013-05-18T23:06:18Z
TMG-chitotriomycin as a probe for the prediction of substrate specificity of β-N-acetylhexosaminidases
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  Author(s): Hiroto Shiota , Hiroshi Kanzaki , Tadashi Hatanaka , Teruhiko Nitoda
  TMG-chitotriomycin (1) produced by the actinomycete Streptomyces annulatus NBRC13369 was examined as a probe for the prediction of substrate specificity of β-N-acetylhexosaminidases (HexNAcases). According to the results of inhibition assays, 14 GH20 HexNAcases from various organisms were divided into 1-sensitive and 1-insensitive enzymes. Three representatives of each group were investigated for their substrate specificity. The 1-sensitive HexNAcases hydrolyzed N-acetylchitooligosaccharides but not N-glycan-type oligosaccharides, whereas the 1-insensitive enzymes hydrolyzed N-glycan-type oligosaccharides but not N-acetylchitooligosaccharides, indicating that TMG-chitotriomycin can be used as a molecular probe to distinguish between chitin-degrading HexNAcases and glycoconjugate-processing HexNAcases.
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  PubDate: 2013-05-14T23:09:05Z
Graphical contents list
- Abstract: Publication date: 7 June 2013
  Source:Carbohydrate Research, Volume 374
  
  PubDate: 2013-05-14T23:09:05Z
Editorial board
- Abstract: Publication date: 7 June 2013
  Source:Carbohydrate Research, Volume 374
  
  PubDate: 2013-05-14T23:09:05Z
A new cytotoxic triterpene saponin from Lysimachia nummularia L.
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  Author(s): Irma Podolak , Paulina Koczurkiewicz , Marta Michalik , Agnieszka Galanty , Paweł Zajdel , Zbigniew Janeczko
  A new glycosylated triterpene 1 (named nummularoside) was isolated from the underground parts of Lysimachia nummularia L. Its chemical structure was elucidated as 3-O-β-{{[β-d-xylopyranosyl-(1→2)]-[β-d-xylopyranosyl-(1→4)]-β-d-glucopyranosyl-(1→4)}-[β-d-glucopyranosyl-(1→2)-]-α-l-arabinopyranosyl]}, protoprimulagenin A on the basis of extensive NMR and MS spectral data. The saponin showed significant activity against prostate cancer cells DU145 and PC3 (EC50 1.2 and 7.4μg/mL, respectively), while it did not affect normal cells (EC50 30μg/mL), in contrast to the reference compound (mitoxanthrone, EC50 0.45μg/mL). Glioblastoma cells were also significantly affected by the tested saponin (EC50 6.0μg/mL), whereas the activity against melanoma cells was moderate (EC50 17.5–23.2μg/mL).
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  PubDate: 2013-05-14T23:09:05Z
Kinetic analysis of inhibition of glucoamylase and active site mutants via chemoselective oxime immobilization of acarbose on SPR chip surfaces
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  Author(s): Jørgen Sauer , Maher Abou Hachem , Birte Svensson , Knud J. Jensen , Mikkel B. Thygesen
  We here report a quantitative study on the binding kinetics of inhibition of the enzyme glucoamylase and how individual active site amino acid mutations influence kinetics. To address this challenge, we have developed a fast and efficient method for anchoring native acarbose to gold chip surfaces for surface plasmon resonance studies employing wild type glucoamylase and active site mutants, Y175F, E180Q, and R54L, as analytes. The key method was the chemoselective and protecting group-free oxime functionalization of the pseudo-tetrasaccharide-based inhibitor acarbose. By using this technique we have shown that at pH 7.0 the association and dissociation rate constants for the acarbose-glucoamylase interaction are 104 M−1 s−1 and 103 s−1, respectively, and that the conformational change to a tight enzyme–inhibitor complex affects the dissociation rate constant by a factor of 102 s−1. Additionally, the acarbose-presenting SPR surfaces could be used as a glucoamylase sensor that allowed rapid, label-free affinity screening of small carbohydrate-based inhibitors in solution, which is otherwise difficult with immobilized enzymes or other proteins.
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  PubDate: 2013-05-14T23:09:05Z
A practical access to glucose- and allose-based (5+5) 3-spiropseudonucleosides from a common intermediate
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  Author(s): Māris Turks , Vitalijs Rodins , Evija Rolava , Pāvels Ostrovskis , Sergey Belyakov
  A practical access to glucose-based and allose-based spirooxazolidinones is reported. The synthetic sequence consisting of TEMPO-catalyzed oxidation of 1,2:5,6-di-O-isopropylidene-α-d-glucofuranose, Henry reaction, and reduction provides amino alcohol with allo-configuration on a multigram scale. Alternatively, water elimination from Henry products followed by a rehydration gives an access to diastereomerically pure glucose-based nitro alcohol which upon reduction provides complementary amino alcohol with gluco-configuration. The latter amino alcohols are transformed into spirooxazolidinones (3-spiropseudonucleosides) via their N-Cbz or N-phenylcarbamate derivatives. The title compounds easily undergo N-derivatization and give highly crystalline materials. Two of the newly obtained (5+5) 3-spiropseudonucleosides are characterized by X-ray crystallography.
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  PubDate: 2013-05-10T23:07:26Z
The effect of deuteration on the structure of bacterial cellulose
- Abstract: Publication date: 7 June 2013
  Source:Carbohydrate Research, Volume 374
  Author(s): Garima Bali , Marcus B. Foston , Hugh M. O’Neill , Barbara R. Evans , Junhong He , Arthur J. Ragauskas
  In vivo generated deuterated bacterial cellulose, cultivated from 100% deuterated glycerol in D2O medium, was analyzed for deuterium incorporation by ionic liquid dissolution and 2H and 1H nuclear magnetic resonance (NMR). A solution NMR method of the dissolved cellulose was used to determine that this bacterial cellulose had 85% deuterium incorporation. Acetylation and 1H and 2H NMR of deuterated bacterial cellulose indicated near equal deuteration at all sites of the glucopyranosyl ring except C-6 which was partly deuterated. Despite the high level deuterium incorporation no significant differences in the molecular and morphological properties were observed for the deuterated and protio bacterial cellulose samples. The highly deuterated bacterial cellulose presented here can be used as a model substrate for studying cellulose biopolymer properties via future small angle neutron scattering (SANS) studies.
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  PubDate: 2013-05-06T23:10:34Z
A heteropolysaccharide from an edible hybrid mushroom pfle 1p: structural and immunostimulating studies
- Abstract: Publication date: 7 June 2013
  Source:Carbohydrate Research, Volume 374
  Author(s): Saikat Maity , Sanjoy K. Bhunia , Ipsita K. Sen , Eshita Kar Mandal , Kousik Maity , Birendra Behera , Tapas K. Maiti , Pijush Mallick , Samir R. Sikdar , Syed S. Islam
  A water-soluble heteropolysaccharide (PS-I) having molecular weight ∼2.1×105 Da was isolated from hot aqueous extract of the fruit bodies of hybrid mushroom pfle 1p. The hybrid mushroom pfle 1p was obtained through intergenic protoplast fusion between Pleurotus florida and Lentinula edodes. The heteropolysaccharide contained d-glucose, d-galactose, and d-mannose in a molar ratio of nearly 4:2:1. The structural investigation of PS-I has been carried out using sugar and methylation analyses as well as 1D/2D NMR experiments (1H, 13C, DEPT-135, DQF-COSY, TOCSY, NOESY, ROESY, HSQC, and HMBC). Based on the results of these experiments, the repeating unit of the PS-I was established as: PS-I showed in vitro macrophage activation by NO production and also stimulated splenocytes and thymocytes.
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  PubDate: 2013-05-06T23:10:34Z
Molecular dynamics study of carbohydrate binding module mutants of fungal cellobiohydrolases
- Abstract: Publication date: 7 June 2013
  Source:Carbohydrate Research, Volume 374
  Author(s): Hirohide Shiiba , Sachio Hayashi , Toshifumi Yui
  The present study reports the systematic survey of binding free energies at the interface between a carbohydrate-binding module (CBM) and a cellulose Iα crystal model using molecular dynamics’ calculations. The two wild type CBMs (Cel7A CBM and Cel6A CBM) have been studied, as well as seven mutants of Cel7A CBM. A comparison of the experimental data for the two wild type and the four mutants CBMs (i.e., Y5A, Y5W, N29A, and Q34A) revealed that the interaction energies of Y5W and Q34A were larger than that of the wild type Cel7A CBM, whereas Y5A and N29A gave smaller values. These predicted values of the interaction energies were compared with the results observed for the adsorbing behaviors of the CBMs.
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  PubDate: 2013-05-06T23:10:34Z
Comparative decomposition kinetics of neutral monosaccharides by microwave and induction heating treatments
- Abstract: Publication date: 28 June 2013
  Source:Carbohydrate Research, Volume 375
  Author(s): Shuntaro Tsubaki , Kiriyo Oono , Ayumu Onda , Kazumichi Yanagisawa , Jun-ichi Azuma
  The stabilities of five neutral monosaccharides (glucose, galactose, mannose, arabinose, and xylose) were kinetically compared after the molecules were submitted to microwave heating (internal heating) and induction heating (external heating) under completely identical thermal histories by employing PID (proportional, integral, and derivative) temperature controlled ovens and homogeneous mixing. By heating in water at 200°C, the rate constants for the decomposition reactions varied from 2.13×10−4 to 3.87×10−4 s−1 for microwave heating; however, the values increased by 1.1- to 1.5-fold for induction heating. Similarly, in a dilute (0.8%) sulfuric acid solution, the decomposition rate constants varied from 0.61×10−3 to 2.00×10−3 s−1 for microwave heating; however, the values increased by 1.5- to 2.2-fold for induction heating. The results show that microwave heating imparts greater stability to neutral monosaccharides than does induction heating. The undesirable decomposition of monosaccharides at the surface boundary of reactor walls may have increased the probability of monosaccharide decomposition during induction heating.
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  PubDate: 2013-05-06T23:10:34Z
New complete structure of Hafnia alvei clinical isolate strain PCM 2670 semi-rough lipopolysaccharide
- Abstract: Publication date: 7 June 2013
  Source:Carbohydrate Research, Volume 374
  Author(s): Ewelina Bobko , Michal Tyras , Wojciech Jachymek
  Hafnia alvei strain PCM 2670 is a clinical isolate from a patient with chronic reproductive tract infection. The novel structure of the semi-rough lipopolysaccharide was established with the use of NMR spectroscopy and mass spectrometry as well as immunochemical techniques. According to the mass spectrometry data, heptose in the oligosaccharide is partially substituted by glycine. H. alvei PCM 2670 core structure encompasses the common core of H. alvei which is modified with two additional galactose units. The 6-substituted galactose is the O-antigen repeating unit substitution residue. The repeating unit consists of five monosaccharide residues and has the following structure: →2)-β-Galp-(1→6)-α-Glcp-(1→6)-αGlcpNAc3OAc-(1→4)-α-GalpA-(1→3)-β-GlcpNAc6OAc-(1→6)-core.
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  PubDate: 2013-05-02T23:11:19Z
Structural studies of an immunoenhancing glucan of an ectomycorrhizal fungus Ramaria botrytis
- Abstract: Publication date: 7 June 2013
  Source:Carbohydrate Research, Volume 374
  Author(s): Sunil K. Bhanja , Dilip Rout , Pradip Patra , Chanchal K. Nandan , Birendra Behera , Tapas K. Maiti , Syed S. Islam
  A water-soluble glucan was isolated from the alkaline extract of an ectomycorrhizal fungus, Ramaria botrytis. On the basis of sugar analysis, methylation analysis, Smith degradation, partial hydrolysis, and 1D/2D NMR studies, the structure of the repeating unit of the glucan was established as: This glucan showed immunostimulating activity by NO production on RAW 264.7, a murine macrophage cell line. Splenocyte and thymocyte proliferation were measured using, respectively, single cell suspensions of spleen and thymus obtained from normal mice.
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  PubDate: 2013-04-28T23:10:17Z
Hydrogen bonding in crystal forms of primary amide functionalised glucose and cellobiose
- Abstract: Publication date: 7 June 2013
  Source:Carbohydrate Research, Volume 374
  Author(s): Humphrey A. Moynihan , John A. Hayes , Kevin S. Eccles , Simon J. Coles , Simon E. Lawrence
  A glucoside and cellobioside of glycolamide were synthesised and the crystal chemistry of these compounds investigated. The amidoglucoside crystallised in the P21 space group. The primary amide group participates in C(7) and C(17) chains also involving the pyranose oxygen and hydroxyl groups. The amidocellobioside crystallised as a methanol solvate in the P21 space group. The amide N–H groups donate hydrogen bonds to oxygen atoms on the cellobiose units, while intramolecular hydrogen bonds give rise to S(7) and S(9) motifs in addition to a R 3 3 (9) motif. A tetra-O-acetylglucoside derivative of thioglycolamide and its sulfoxide derivative were synthesised to examine the effect of protecting the glucopyranose hydroxyl groups. The thioglycolamido derivative, which crystallised in the P212121 space group, featured amide N–H groups donating to the glucopyranose oxygen and an acetyloxy group. The sulfoxy derivative crystallised in the P21 space group and featured the primary amide groups forming R 2 3 (8) motifs generating a 21 ladder.
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  PubDate: 2013-04-24T23:10:11Z
Preparation of branched cyclomaltoheptaose with 3-O-α-l-fucopyranosyl-α-d-mannopyranose and changes in fucosylation of HCT116 cells treated with the fucose-modified cyclomaltoheptaose
- Abstract: Publication date: 7 June 2013
  Source:Carbohydrate Research, Volume 374
  Author(s): Madoka Kimura , Yuki Masui , Yuko Shirai , Chie Honda , Kenta Moriwaki , Taku Imai , Uichiro Takagi , Takaaki Kiryu , Taro Kiso , Hiromi Murakami , Hirofumi Nakano , Sumio Kitahata , Eiji Miyoshi , Toshiko Tanimoto
  From a mixture of 4-nitrophenyl α-l-fucopyranoside and d-mannopyranose, 3-O-α-l-fucopyranosyl-d-mannopyranose was synthesised through the transferring action of α-fucosidase (Sumizyme PHY). 6I,6IV-Di-O-(3-O-α-l-fucopyranosyl-α-d-mannopyranosyl)-cyclomaltoheptaose {8, 6I,6IV-di-O-[α-l-Fuc-(1→3)-α-d-Man]-βCD} was chemically synthesised using the trichloroacetimidate method. The structures were confirmed by MS and NMR spectroscopy. A cell-based assay using the fucosyl βCD derivatives, including the newly synthesised 8, showed that derivatives with two branches of the α-l-Fuc or α-l-Fuc-(1→3)-α-d-Man residues possessed slight growth-promoting effects and lower toxicity in HCT116 cells compared to those with one branch. These compounds may be useful as drug carriers in targeted drug delivery systems.
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  PubDate: 2013-04-24T23:10:11Z
The synthesis of a series of deoxygenated 2,3-difluoro-N-acteylneuraminic acid derivatives as potential sialidase inhibitors
- Abstract: Publication date: 7 June 2013
  Source:Carbohydrate Research, Volume 374
  Author(s): Stefan Hader , Andrew G. Watts
  Here we describe the successful syntheses of a series of 4-, 7-, 8- and 9-deoxygenated 2,3-difluoro-N-acetylneuraminic acid derivatives as potential mechanism-based inhibitors of sialidases. The syntheses commenced utilising an enzyme-catalysed aldolase reaction between N-acetyl mannosamine and β-fluoropyruvic acid to give 3-fluoro-N-acetyl-neuraminic acid. This common intermediate was then used in selective protection protocols and Barton–McCombie deoxygenations to generate the complete set of mono-deoxygenated 3-fluoro-N-acetylneuraminic acid derivatives. Finally, a fluorination step utilising (diethylamino)sulfur trifluoride (DAST) was used to successfully generate each of the target difluorides.
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  PubDate: 2013-04-24T23:10:11Z
Stereoselective synthesis of (2S,3S,4R,5S)-3,4-dihydroxy-2,5-dihydroxymethyl pyrrolidine from l-sorbose
- Abstract: Publication date: 7 June 2013
  Source:Carbohydrate Research, Volume 374
  Author(s): Sébastien Balieu , Arnaud Guilleret , Romain Reynaud , Agathe Martinez , Arnaud Haudrechy
  One of the most frequently synthesized iminosugar derivatives is DMDP. Starting from l-sorbose, a practical method for the synthesis of derivatives of this five-membered iminocyclitol has been developed, involving straightforward steps and a convenient selective reduction of a ketoxime intermediate.
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  PubDate: 2013-04-20T23:08:00Z
Concise synthesis of flavocommelin, 7-O-methylapigenin 6-C-, 4′-O-bis-β-d-glucoside, a component of the blue supramolecular pigment from Commelina communis
- Abstract: Publication date: 7 June 2013
  Source:Carbohydrate Research, Volume 374
  Author(s): Kazufumi Misawa , Yoshiki Gunji , Shingo Sato
  Flavocommelin, 7-O-methylapigenin 6-C-, 4′-O-bis-β-d-glucoside, was synthesized in 9 steps from the C-glycosylation of 6-O-benzy-4-O-methylphloroacetophenone via the introduction of a cinnamoyl residue by aldol condensation and the formation of a C-ring by regioselective and oxidative ring-closure to regio- and stereoselective O-glycosylation for an overall yield of 31%.
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  PubDate: 2013-04-20T23:08:00Z
High diastereoselective vinylogous Mannich reaction induced by O-pivaloylated d-galactosylamine as the chiral auxiliary: stereoselective synthesis of 8-arylazocan-2-one
- Abstract: Publication date: 7 June 2013
  Source:Carbohydrate Research, Volume 374
  Author(s): Bing Cui , Gang Hou , Yan Cai , Zhiwei Miao
  The diastereospecific formation of β-N-glycosidically linked α,β-unsaturated δ-amino aldehyde derivatives has been achieved with high yield via a vinylogous Mannich reaction. The reaction was performed by using a O-pivaloylated galactosyl amine as a chiral template and AlCl3 as a promoter in THF. (S)-8-(p-Nitrophenyl) azocan-2-one can be stereoselective synthesized from (S) ethyl 7-galactosylamino-7-(p-nitrophenyl)hepta-2,4-dienoate by sequential hydrogenation of the double bond, cyclic lactam formation, and removal of the N-glycosidic auxiliary under basic conditions.
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  PubDate: 2013-04-20T23:08:00Z