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  Subjects -> CHEMISTRY (Total: 767 journals)
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    - CHEMISTRY (532 journals)
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CHEMISTRY (532 journals)                  1 2 3 4 5 6 | Last

2D Materials     Hybrid Journal   (Followers: 3)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 31)
ACS Catalysis     Full-text available via subscription   (Followers: 23)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 13)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 8)
ACS Macro Letters     Full-text available via subscription   (Followers: 17)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 25)
ACS Nano     Full-text available via subscription   (Followers: 259)
ACS Photonics     Full-text available via subscription   (Followers: 2)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 8)
Acta Chemica Iasi     Open Access  
Acta Chimica Slovaca     Open Access   (Followers: 5)
Acta Chromatographica     Full-text available via subscription   (Followers: 10)
Acta Facultatis Medicae Naissensis     Open Access   (Followers: 1)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 4)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 2)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 4)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 8)
Advanced Functional Materials     Hybrid Journal   (Followers: 34)
Advances in Chemical Engineering and Science     Open Access   (Followers: 21)
Advances in Chemical Science     Open Access   (Followers: 8)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 13)
Advances in Drug Research     Full-text available via subscription   (Followers: 17)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 7)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 12)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 13)
Advances in Nanoparticles     Open Access   (Followers: 11)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 8)
Advances in Polymer Science     Hybrid Journal   (Followers: 38)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 10)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 4)
African Journal of Chemical Education     Open Access   (Followers: 1)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 4)
Afrique Science : Revue Internationale des Sciences et Technologie     Open Access  
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Alchemy     Open Access   (Followers: 2)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 4)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 28)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 157)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 11)
American Journal of Chemistry     Open Access   (Followers: 17)
American Journal of Plant Physiology     Open Access   (Followers: 9)
American Mineralogist     Full-text available via subscription   (Followers: 2)
Analyst     Full-text available via subscription   (Followers: 35)
Angewandte Chemie     Hybrid Journal   (Followers: 15)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 203)
Annales UMCS, Chemia     Open Access   (Followers: 2)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 1)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 2)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 4)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 10)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 12)
Anti-Infective Agents     Hybrid Journal   (Followers: 1)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 4)
Applied Spectroscopy     Full-text available via subscription   (Followers: 12)
Applied Surface Science     Hybrid Journal   (Followers: 14)
Arabian Journal of Chemistry     Full-text available via subscription   (Followers: 6)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 4)
Autophagy     Full-text available via subscription   (Followers: 1)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 6)
Biochemistry     Full-text available via subscription   (Followers: 191)
Biochemistry Insights     Open Access   (Followers: 4)
Biochemistry Research International     Open Access   (Followers: 4)
BioChip Journal     Hybrid Journal   (Followers: 1)
Bioinorganic Chemistry and Applications     Open Access   (Followers: 4)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 1)
Biointerphases     Open Access  
Biomacromolecules     Full-text available via subscription   (Followers: 17)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 5)
Biomedical Chromatography     Hybrid Journal   (Followers: 7)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 2)
BioNanoScience     Partially Free   (Followers: 4)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 30)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 24)
Bioorganic Chemistry     Hybrid Journal   (Followers: 5)
Biopolymers     Hybrid Journal   (Followers: 13)
Biosensors     Open Access   (Followers: 3)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 1)
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 1)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 12)
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 3)
Canadian Journal of Chemistry     Full-text available via subscription   (Followers: 6)
Canadian Mineralogist     Full-text available via subscription   (Followers: 1)
Carbohydrate Research     Hybrid Journal   (Followers: 10)
Carbon     Hybrid Journal   (Followers: 38)
Catalysis for Sustainable Energy     Open Access   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 4)
Catalysis Science and Technology     Free   (Followers: 4)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 4)
Catalysts     Open Access   (Followers: 6)
Cellulose     Hybrid Journal   (Followers: 4)
Central European Journal of Chemistry     Hybrid Journal   (Followers: 5)
Cereal Chemistry     Full-text available via subscription   (Followers: 3)

        1 2 3 4 5 6 | Last

Journal Cover Carbohydrate Research
   Journal TOC RSS feeds Export to Zotero [12 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0008-6215 - ISSN (Online) 0008-6215
     Published by Elsevier Homepage  [2566 journals]   [SJR: 0.675]   [H-I: 77]
  • A Synthesis of 6-Deoxy-6-Fluorosucrose Suitable For PET Applications
    • Abstract: Publication date: Available online 21 September 2014
      Source:Carbohydrate Research
      Author(s): Xuefeng Gao , Vikram Gaddam , Michael Harmata
      A new route to 6-deoxy-6-fluorosucrose has been developed. The process proceeds in 8 linear steps in 25% overall yield from sucrose. The steps incorporating fluorine and subsequent deprotection are quite rapid, making the procedure useful in the context of 18F-labelling for PET applications.
      Graphical abstract image

      PubDate: 2014-09-25T23:47:00Z
       
  • A convenient synthesis of novel aza-C-disaccharide analogues
    • Abstract: Publication date: 29 October 2014
      Source:Carbohydrate Research, Volume 398
      Author(s): Pingzhu Zhang , Cuicui Li , Hailong Yang , Hua Wei , Zhichao Xia , Donglai Ma , Hua Chen , Kerang Wang , Xiaoliu Li
      Novel aza-C-disaccharide analogues have been conveniently synthesized by using the isoxazoline-linked C-disaccharide derivatives as the intermediates. Firstly, the CN of isoxazoline was reduced to C–N by using DIBAL-H as reducing agent, then followed by the tandem multi-step reactions through catalytic hydrogenation with Pd(OH)2/C involving debenzylated, reductive cleavage of the N–O, condensation–cyclization of the aldehyde and the in situ generated amine group to form imine CN and then CN hydrogenation to form C–N, thus providing a practical and new access to the synthesis of novel aza-C-disaccharide analogues.
      Graphical abstract image

      PubDate: 2014-09-20T23:42:05Z
       
  • Graphical contents list
    • Abstract: Publication date: 9 October 2014
      Source:Carbohydrate Research, Volume 397




      PubDate: 2014-09-20T23:42:05Z
       
  • The new sulfated O-specific polysaccharide from marine bacterium Cobetia
           pacifica KMM 3878, containing 3,4-O-[(S)-1-carboxyethylidene]-d-galactose
           and 2,3-O-disulfate-d-galactose
    • Abstract: Publication date: 9 October 2014
      Source:Carbohydrate Research, Volume 397
      Author(s): Maxim S. Kokoulin , Anatoliy I. Kalinovsky , Nadezhda A. Komandrova , Svetlana V. Tomshich , Lyudmila A. Romanenko , Victor E. Vaskovsky
      The O-specific polysaccharide was isolated from the lipopolysaccharide of Cobetia pacifica KMM 3878 and studied by chemical methods along with 1H and 13C NMR spectroscopy, including, 1D TOCSY and 2D 1H, 1H COSY, 1H, 13C HSQC, 1H, 1H ROESY, 1H, 13C HMBC and 1H, 13C H2BC experiments. The following new structure of the sulfated O-polysaccharide from C. pacifica KMM 3878 containing 3,4-O-[(S)-1-carboxyethylidene]-d-galactose and 2,3-O-disulfate-d-galactose was established: →4)-β-d-Gal2,3R-(1→6)-β-d-Gal3,4(S-Pyr)-(1→6)-β-d-Gal-(1→ Where R is –SO3H.
      Graphical abstract image

      PubDate: 2014-09-20T23:42:05Z
       
  • Editorial board
    • Abstract: Publication date: 9 October 2014
      Source:Carbohydrate Research, Volume 397




      PubDate: 2014-09-20T23:42:05Z
       
  • Highly regio- and diastereoselective, acidic clay supported intramolecular
           nitrile oxide–alkene cycloaddition on d-ribose derived nitriles: an
           efficient synthetic route to isoxazoline fused five and six membered
           carbocycles
    • Abstract: Publication date: 29 October 2014
      Source:Carbohydrate Research, Volume 398
      Author(s): Amarendra Panda , Sulagna Das , Shantanu Pal
      An efficient synthetic route to isoxazoline fused carbocycles from carbohydrate scaffolds that comprise of free hydroxyl group(s) is described with high regio- and stereoselectivity. Montmorillonite K-10/chloramine T oxidation and in situ intramolecular nitrile oxide–alkene cycloaddition (INOC) of d-ribose derived oximes have been developed for the diversity oriented synthesis of isoxazoline fused five and six membered carbocycles.
      Graphical abstract image

      PubDate: 2014-09-20T23:42:05Z
       
  • Influence of glycosidic linkage on the solution conformational entropy of
           gluco- and mannobioses
    • Abstract: Publication date: 29 October 2014
      Source:Carbohydrate Research, Volume 398
      Author(s): Mallory J. Morris , André M. Striegel
      Employing size-exclusion chromatography, an entropically-controlled separation technique, we have determined the solution conformational entropy (−ΔS) of (1→2)-, (1→3)-, (1→4)-, and (1→6)-linked gluco- and mannobioses with an α anomeric configuration, at quasi-physiological conditions of solvent, temperature, and pH. The experiments allowed for comparison both among and between each series of disaccharides. Results included quantitative information on how the additional degrees of freedom of the (1→6) linkage influence −ΔS, as well as on the influence on solution conformational entropy of a single axial hydroxyl (OH) group and of the relative positioning of the glycosidic linkage and the anomeric hydroxyl group. We also contrasted the (1→4)-α-d-linked gluco- and mannobioses to their counterparts with a β anomeric configuration. Comparison between (1→4)-β-d-linked glucobiose (cellobiose) and (1→4)-β-d-linked mannobiose showed that the restrictive effect on solution flexibility of the axial OH in the latter disaccharide is offset by the combined effect of hydroxyl group orientation and anomeric configuration on intramolecular hydrogen bonding.
      Graphical abstract image

      PubDate: 2014-09-20T23:42:05Z
       
  • Isolation of a new disaccharide nucleoside from Helleborus caucasicus:
           structure elucidation and total synthesis of hellecaucaside A and its
           β-anomer
    • Abstract: Publication date: 29 October 2014
      Source:Carbohydrate Research, Volume 398
      Author(s): Balla Sylla , Charles Gauthier , Jean Legault , Pierre-Yves Fleury , Serge Lavoie , Vakhtang Mshvildadze , Tamar Muzashvili , Eter Kemertelidze , André Pichette
      Hellecaucaside A, a new disaccharide nucleoside featuring a 2′-O-α-d-ribofuranosyluridine skeleton and a 4-hydroxybenzoyl group at the 5′ position, was isolated from the underground part of Helleborus caucasicus. The structure of the compound was elucidated by means of chemical degradation and spectroscopic analyses, such as 1D/2D NMR, chiral-GC, and HRMS. The total synthesis of hellecaucaside A and its β-anomer was accomplished, unequivocally confirming the structure of the natural product.
      Graphical abstract image

      PubDate: 2014-09-20T23:42:05Z
       
  • Structure and gene cluster organization of the O-antigen of Providencia
           alcalifaciens O45:H25
    • Abstract: Publication date: 29 October 2014
      Source:Carbohydrate Research, Volume 398
      Author(s): Olga G. Ovchinnikova , Alexander S. Shashkov , Magdalena Moryl , Bin Liu , Antoni Rozalski , Yuriy A. Knirel
      O-Polysaccharide was obtained by mild acid degradation of the lipopolysaccharide of Providencia alcalifaciens O45:H25 and studied by sugar analysis, Smith degradation, and 1H and 13C NMR spectroscopy. The following structure of the pentasaccharide repeat of the O-polysaccharide was established: The O-antigen gene cluster of P. alcalifaciens O45 was sequenced and found to be in full agreement with the O-polysaccharide structure established.
      Graphical abstract image

      PubDate: 2014-09-20T23:42:05Z
       
  • The structure of O-polysaccharide isolated from Cronobacter universalis
           NCTC 9529T
    • Abstract: Publication date: 29 October 2014
      Source:Carbohydrate Research, Volume 398
      Author(s): Kinga Marszewska , Małgorzata Czerwicka , Stephen J. Forsythe , Ewelina Sałdak , Sylwia Szulta , Halina Dziadziuszko , Karolina Ossowska , Zbigniew Kaczyński
      The O-polysaccharide (OPS) was isolated from Cronobacter universalis NCTC 9529T, a new species in the genus Cronobacter, which was created by the reclassification of the species Enterobacter sakazakii. Purified polysaccharide was analyzed by NMR spectroscopy (1H, COSY, TOCSY, ROESY, HSQC, and HSQC-TOCSY) and chemical methods. The monosaccharide derivatives were analyzed by gas chromatography and gas chromatography–mass spectrometry. These experiments enabled the type and number of monosaccharides in the repeating unit of OPS, their positions of linkages, and absolute configuration to be determined. Together the chemical analysis established a structure of the OPS of C. universalis NCTC 9529T. OPS isolated from C. universalis was structurally characterized for the first time.
      Graphical abstract image

      PubDate: 2014-09-20T23:42:05Z
       
  • Structural studies of the polysaccharides from the lipopolysaccharides of
           Azospirillum brasilense Sp246 and SpBr14
    • Abstract: Publication date: 29 October 2014
      Source:Carbohydrate Research, Volume 398
      Author(s): Elena N. Sigida , Yuliya P. Fedonenko , Alexander S. Shashkov , Vyacheslav S. Grinev , Evelina L. Zdorovenko , Svetlana A. Konnova , Vladimir V. Ignatov , Yuriy A. Knirel
      Lipopolysaccharides from closely related Azospirillum brasilense strains, Sp246 and SpBr14, were obtained by phenol–water extraction. Mild acid hydrolysis of the lipopolysaccharides followed by GPC on Sephadex G-50 resulted in polysaccharide mixtures. On the basis of sugar and methylation analyses, Smith degradation and 1H and 13C NMR spectroscopy data, it was concluded that both bacteria possess the same two distinct polysaccharides having structures 1 and 2: Structure 1 has been reported earlier for a polysaccharide of A. brasilense 54 [Fedonenko et al., 2011]6 whereas to our knowledge structure 2 has not been hitherto found in bacterial polysaccharides.
      Graphical abstract image

      PubDate: 2014-09-20T23:42:05Z
       
  • 1,2-trans-1-Dihydroxyboryl benzyl S-glycoside as glycosyl donor
    • Abstract: Publication date: 29 October 2014
      Source:Carbohydrate Research, Volume 398
      Author(s): Xiao Liu , Bingbing Zhang , Xiangying Gu , Guohua Chen , Lin Chen , Xin Wang , Bing Xiong , Qi-Dong You , Yue-Lei Chen , Jingkang Shen
      Activated by NBS, readily available 1,2-trans-1-dihydroxyboryl benzyl S-glycosides served as glycosyl donors and reacted with certain simple alcohol acceptors to produce pure 1,2-cis-O-glycosides in moderate yields. The boronic acid moiety was revealed essential in the glycosylation for product formation and good anomeric ratio. The preliminary model reactions suggested that glycosyl aryl boronic acids could be used for stereoselective glycosylation.
      Graphical abstract image

      PubDate: 2014-09-20T23:42:05Z
       
  • Investigation of the complexation of albendazole with cyclodextrins for
           the design of new antiparasitic formulations
    • Abstract: Publication date: 29 October 2014
      Source:Carbohydrate Research, Volume 398
      Author(s): Bénédicte Pradines , Jean-François Gallard , Bogdan I. Iorga , Claire Gueutin , Philippe M. Loiseau , Gilles Ponchel , Kawthar Bouchemal
      Albendazole (ABZ) exhibits a potent antiparasitic activity against a broad spectrum of parasites. Unfortunately, the very low water solubility of ABZ (0.2μgmL−1, 0.7μM) impairs considerably its formulation. Phase solubility diagrams showed that α-cyclodextrin (10% w/w), hydroxypropyl-β-cyclodextrin (40% w/w) and sulfobutylether-β-cyclodextrin (40% w/w) allowed an increase of apparent solubility with enhancement factors of 570, 3970, and 5880, respectively. The apparent aqueous solubility of ABZ was markedly increased from 0.2μgmL−1 (0.7μM) without cyclodextrins to 1.52mgmL−1 (5.69mM) with random methyl-β-cyclodextrin (Me-β-CD) (40% w/w). This corresponds to an apparent solubility enhancement factor of 7600 which is the maximal enhancement factor of ABZ apparent aqueous solubility ever reported in the literature using conventional cyclodextrins. The complexation mechanism between ABZ and cyclodextrins has been investigated using phase solubility diagrams, nuclear magnetic resonance (1H NMR) coupled with two-dimensional nuclear Overhauser effect (NOESY) experiments and molecular docking calculations. The results showed that the central bicyclic fragment from ABZ interacts with Me-β-CD according to 1:1 stoichiometry.
      Graphical abstract image

      PubDate: 2014-09-20T23:42:05Z
       
  • One-pot SSA-catalyzed β-elimination: An efficient and inexpensive
           protocol for easy access to the glycal of sialic acid
    • Abstract: Publication date: Available online 17 September 2014
      Source:Carbohydrate Research
      Author(s): Erickson M. Paragas , I. Abrrey Monreal , Chris M. Vasil , Jonel P. Saludes
      Neu5Ac2en1Me per-OAc, the fully protected glycal of sialic acid, is a key intermediate in the discovery of therapeutics and diagnostics, including anti-influenza drugs and proteolysis resistant peptidomimetic foldamers. The synthesis of this sialic acid derivative, however, still relies on standard sugar chemistry that utilizes multi-step methodologies. Herein we report a facile and highly efficient microwave-assisted preparation of Neu5Ac1Me using silica sulfuric acid (SSA) as solid-supported acid catalyst that is one- to two-orders of magnitude faster than standard procedures. We also describe the microwave-assisted and SSA-catalyzed one-pot, rapid, solvent free reaction that combines both peracetylation and β-elimination reactions in one step to generate the glycal from Neu5Ac1Me. We coined the term One-pot SSA-catalyzed Technology for β-Elimination Protocol (OneSTEP) to describe this least laborious, most efficient, and practical preparation to date of Neu5Ac2en1Me per-OAc in terms of yield, time, reagent cost, and waste generation.
      Graphical abstract image

      PubDate: 2014-09-20T23:42:05Z
       
  • Preface
    • Abstract: Publication date: Available online 19 September 2014
      Source:Carbohydrate Research
      Author(s): N. Jayaraman



      PubDate: 2014-09-20T23:42:05Z
       
  • Structural studies of the exopolysaccharide from Lactobacillus plantarum
           C88 using NMR spectroscopy and the program CASPER
    • Abstract: Publication date: Available online 18 September 2014
      Source:Carbohydrate Research
      Author(s): Carolina Fontana , Shengyu Li , Zhennai Yang , Göran Widmalm
      Some lactic acid bacteria, such as those of the Lactobacillus genus, have the ability to produce exopolysaccharides (EPSs) that confer favorable physicochemical properties to food and/or beneficial physiological effects on human health. In particular, the EPS of L. plantarum C88 has recently demonstrated in vitro antioxidant activity and, herein, its structure has been investigated using NMR spectroscopy and the computer program CASPER (Computer Assisted Spectrum Evaluation of Regular polysaccharides). The pentasaccharide repeating unit of the O-deacetylated EPS consists of a trisaccharide backbone, →4)- α-d-Galp-(1→2)- α-d-Glcp-(1→3)-β-d-Glcp-(1→, with terminal d-Glc and d-Gal residues (1.0 and 0.8 equivalents per repeating unit, respectively) extending from O3 and O6, respectively, of the →4)- α-d-Galp-(1→ residue. In the native EPS an O-acetyl group is present, 0.85 equivalents per repeating unit, at O2 of the α-linked galactose residue; thus the repeating unit of the EPS has the following structure: →4)[β-d-Glcp-(1→3)][ β -d-Galp-(1→6)] α -d-Galp2Ac-(1→2)- α -d-Glcp-(1→3)- β -d-Glcp-(1→. These structural features, and the chain length (∼103 repeating units on average, determined in a previous study), are expected to play an important role in defining the physicochemical properties of the polymer.
      Graphical abstract image

      PubDate: 2014-09-20T23:42:05Z
       
  • Efficient Synthesis of Ethisteron Glyconjugate via bis-Triazole Linkage
    • Abstract: Publication date: Available online 16 September 2014
      Source:Carbohydrate Research
      Author(s): Kunj B. Mishra , Bhuwan B. Mishra , Vinod K. Tiwari
      Synthesis of sugar based triazolyl azido-alcohols was accomplished via one pot click reaction of glycosyl alkynes with epichlorohydrin in aqueous medium. All the developed triazolyl azido-alcohols were further utilized for the synthesis of bis-triazolyl ethisterone glycoconjugates using CuAAC reaction. The developed triazole-linked ethisterone glycoconjugates would be crucial in androgen receptor pharmacology and chemical biology.
      Graphical abstract image

      PubDate: 2014-09-17T23:40:07Z
       
  • Structural determination of Streptococcus pneumoniae repeat units in
           serotype 41A and 41F capsular polysaccharides to probe gene functions in
           the corresponding capsular biosynthetic loci
    • Abstract: Publication date: Available online 16 September 2014
      Source:Carbohydrate Research
      Author(s): Bent O. Petersen , Ian C. Skovsted , Berit Smestad Paulsen , Antonio R. Redondo , Sebastian Meier
      We report the repeating unit structures of the native capsular polysaccharides of S. pneumoniae serotypes 41A and 41F. Structural determinations yielded six carbohydrate units in the doubly branched repeating unit to give the following structure for serotype 41A: The structure determinations were motivated (1) by an ambition to help close the remaining gaps in S. pneumoniae capsular polysaccharide structures, and (2) by the attempt to derive functional annotations of carbohydrate active enzymes in the biosynthesis of bacterial polysaccharides from the determined structures. An activity present in 41F but not 41A is identified as an acetyltransferase acting on the rhamnopyranosoyl sidechain E. The genes encoding the formation of the six glycosidic bonds in serogroup 41 were determined from the capsular polysaccharide structures of serotype 41A, 41F and genetically related serotypes, in conjunction with corresponding genomic information and computational homology searches. In combination with complementary information, NMR spectroscopy considerably simplifies the functional annotation of carbohydrate active enzymes in the biosynthesis of bacterial polysaccharides.
      Graphical abstract image Highlights

      PubDate: 2014-09-17T23:40:07Z
       
  • Electrochemical Synthesis of Nanostructured Gold Film for the Study of
           Carbohydrate-Lectin Interactions Using Localized Surface Plasmon Resonance
           Spectroscopy
    • Abstract: Publication date: Available online 16 September 2014
      Source:Carbohydrate Research
      Author(s): Jay K. Bhattarai , Abeera Sharma , Kohki Fujikawa , Alexei V. Demchenko , Keith J. Stine
      Localized surface plasmon resonance (LSPR) spectroscopy is a label-free chemical and biological molecular sensing technique whose sensitivity depends upon development of nanostructured transducers. Herein, we report a facile electrochemical method for fabricating sensitive, novel and robust nanostructured gold films (NGF) that can be used as transducers in LSPR spectroscopy. The NGF was prepared by electrodepositing gold from potassium dicyanoaurate(I) solution onto a flat gold surface using two sequential controlled potential steps. Imaging by scanning electron microscopy reveals an interesting morphology of randomly configured block-like nanostructures. The bulk refractive index sensitivity of the prepared NGF is near 100 nm/RIU and the initial peak in the reflectance spectrum is around 520 nm. In addition, we have studied the interaction between carbohydrate (mannose) and lectin (Concanavalin A) on the NGF surface using LSPR spectroscopy by measuring the interaction of 8-mercaptooctyl-α-D-mannopyranoside (αMan-C8-SH) with Concanavalin A by first immobilizing αMan-C8-SH in mixed SAMs with 3,6-dioxa-8-mercaptooctanol on the NGF surface. The interaction of Con A with the mixed SAMs is confirmed using electrochemical impedance spectroscopy. Finally, the NGF surface was regenerated to its original sensitivity by removing the SAM and the bound biomolecules. The results from these experiments contribute toward the development of cheap and sensitive LSPR based sensors that can be used for diagnostic and other analytical purposes.
      Graphical abstract image

      PubDate: 2014-09-17T23:40:07Z
       
  • Susceptibility of enoxaparin reducing end amino sugars to periodate
           oxidation
    • Abstract: Publication date: Available online 10 September 2014
      Source:Carbohydrate Research
      Author(s): Anna Alekseeva , Stefano Elli , Cesare Cosentino , Giangiacomo Torri , Annamaria Naggi
      There is a growing interest on glycol-split low-molecular weight heparins (gs-LMWHs), obtained by periodate oxidation of LMWHs, optionally followed by borohydride reduction, as potential anticancer and anti-inflammatory drugs. However, their structural characterization is still a challenging task, mainly because of the high microheterogeneity of the starting material. In addition, susceptibility to oxidation of some end-groups of LMWHs induces additional heterogeneity, making analysis of gs-LMWHs more complex. In our previous study we showed that 1,6-anhydro-D-mannosamine N-sulfate was affected by periodate, while its epimer 1,6-anhydro-D-glucosamine N-sulfate was resistant. In order to understand the apparently anomalous behavior of terminal 1,6-anhydro-D-mannosamine N-sulfate residues, in the present work we have studied by NMR spectroscopy and LC/MS the behavior of the reducing end amino sugar residues of the tetrasaccharides, isolated from the LMWH enoxaparin, in the presence of periodate. Their molecular mechanics conformational characterisation has been also performed. We have shown that the C(2)-C(3) bond of the 1,6-anhydro-D-mannosamine residue can be split by periodate despite the N-substitution. Moreover, we have found that both terminal D-mannosamine N-sulfate and D-glucosamine N-sulfate, lacking the 1,6-anhydro-bridge, can be also oxidized by periodate but with significantly lower rate. The present results suggest that the cis-e-/a-position of OH and NHSO3 - groups of N-sulfated 1,6-anhydro-D-mannosamine is not the only factor that makes these end residues susceptible to the oxidation. The 1,6-anhydro-bridge that “blocks” the ring conformation appears another crucial factor for oxidation to occur. Moreover, we have shown that controlling the reaction time could permit to selectively split non-sulfated iduronic acids of enoxaparin chains without oxidizing terminal amino sugar residues, a finding that may be useful to obtain more structurally homogeneous gs-LMHWs.
      Graphical abstract image

      PubDate: 2014-09-13T23:36:58Z
       
  • Galactose grafting on poly(ε-caprolactone) substrates for tissue
           engineering”: a preliminary study
    • Abstract: Publication date: Available online 10 September 2014
      Source:Carbohydrate Research
      Author(s): Laura Russo , Teresa Russo , Chiara Battocchio , Francesca Taraballi , Antonio Gloria , Ugo D’Amora , Roberto De Santis , Giovanni Polzonetti , Francesco Nicotra , Luigi Ambrosio , Laura Cipolla
      The grafting of galactose units onto poly(ε-caprolactone) (PCL) substrates by a wet chemistry two-step procedure is proposed. Even though a reduction of hardness from 0.58-0.31 GPa to 0.12−0.05 GPa is achieved, the chemical functionalization does not negatively affect the tensile modulus (332.2 ± 31.3 MPa and 328.5 ± 34.7 MPa for unmodified and surface-modified PCL, respectively) and strength (15.1 ± 1.3 MPa and 14.8 ± 1.5 MPa as assessed before and after the surface modification, respectively), as well as the mechanical behavior evaluated through small punch test. XPS and Enzyme-linked lectin assay (ELLA) demonstrates the presence, and also the correct exposition of the saccharidic epitope on PCL substrates. The introduction of carbohydrate moieties on the PCL surfaces clearly enhances the hydrophilicity of the substrate, as the water contact angle decreases from 82.1± 5.8° to 62.1± 4.2°. Furthermore, preliminary biological analysis shows human mesenchymal stem cell viability over time and an improvement of cell adhesion and spreading.
      Graphical abstract image

      PubDate: 2014-09-13T23:36:58Z
       
  • Automated Chip-Nanoelectrospray Mass Spectrometry for Glycourinomics in
           Schindler Disease type I
    • Abstract: Publication date: Available online 6 September 2014
      Source:Carbohydrate Research
      Author(s): Mirela Sarbu , Adrian Robu , Jasna Peter-Katalinic , Alina D. Zamfir
      In this study an integrative mass spectrometry (MS) approach based on fully automated chip-nanoelectrospray quadrupole time-of-flight was optimized and applied for the discovery and structural characterization of O-glycopeptides in a fraction from the urine of a patient diagnosed with Schindler disease type I. A mixture of O-glycopeptides extracted and purified from an age matched healthy subject served as the control. 49 glycoforms were discovered in the investigated urine fraction from Schindler disease vs. only 14 in control urine. Structures with relevant biological significance, previously not described, such as O-fucosylated tetrasaccharides and chains up to pentadecamers O-linked to serine, threonine or threonine-proline were identified in the pathological urine and characterized by tandem MS (MS/MS). A number of 29 species discovered here, most of which with long chain glycans, were not previously reported as associated to this condition. All glycopeptides were detected in only 1 min analysis time, with a sample consumption situated in the femtomole range.
      Graphical abstract image Highlights

      PubDate: 2014-09-09T22:58:19Z
       
  • Synthesis, characterization and in vitro evaluation of
           artesunate-β-cyclodextrin conjugates as novel anti-cancer prodrugs
    • Abstract: Publication date: Available online 8 September 2014
      Source:Carbohydrate Research
      Author(s): Rui-jian Jiang , Yu-lin Zhao , Yun-jian Chen , Dan Xiao , Fen Wang , Bin Han , Jian Yang , Xia-li Liao , Li-Juan Yang , Chuan-zhu Gao , Bo Yang
      A novel series of artesunate-β-cyclodextrin (ATS-β-CD) conjugates, in which artesunate (ATS) was coupled covalently to one of the primary hydroxyl groups of β-cyclodextrin (β-CD) through amino bond formation, were synthesized and characterized by 1H NMR, HRMS, 2D NMR (ROESY), X-ray diffraction (XRD) and Thermogravimetric analysis (TGA). The results showed that the aqueous solubility of ATS-β-CD conjugates was 26∼45 times better than that of free ATS. The cytotoxicity of the ATS-β-CD conjugates was evaluated on human colon cancer cell lines HCT116, LOVO, SW480 and HT-29, and the results indicated that ATS-2NβCD exhibited a very high cytotoxicity against HCT116, LOVO and HT-29 with IC50 values of 0.58, 1.62 and 5.18 μmol/L respectively. In addition, the supposition of better cytotoxicity was further supported by the control experiment of fluorescent cyclodextrin.
      Graphical abstract image

      PubDate: 2014-09-09T22:58:19Z
       
  • Concise synthesis of the tetrasaccharide repeating unit of the
           O-polysaccahride isolated from Edwardsiella tarda PCM 1156 strain
    • Abstract: Publication date: Available online 21 August 2014
      Source:Carbohydrate Research
      Author(s): Rituparna Das , Mukul Mahanti , Balaram Mukhopadhyay
      A convergent strategy has been developed for the synthesis of the tetrasaccharide repeating unit of the O-antigen from Edwardsiella tarda PCM 1156. Sequential glycosylations of a series of rationally protected monosaccharide intermediates were achieved either by the activation of thioglycosides using NIS in conjunction with H2SO4-silica or by activation of trichloroacetimidate by H2SO4-silica only. All glycosylation reactions resulted in the formation of the desired linkage with absolute stereoselectivity and afforded the required derivatives in good to excellent yields. Both azido and phthalimido groups have been used as the precursor of the desired acetamido group depending on the requirement of1,2-cis or 1,2-trans glycosidic linkage.
      Graphical abstract image Highlights

      PubDate: 2014-09-04T22:13:59Z
       
  • myo-Inositol 1,3-acetals as early intermediates during the synthesis of
           cyclitol derivatives
    • Abstract: Publication date: Available online 23 August 2014
      Source:Carbohydrate Research
      Author(s): Bharat P. Gurale , Richa S. Sardessai , Mysore S. Shashidhar
      Synthetic sequences starting from commercially available myo-inositol necessarily involve protection – deprotection strategies of its six hydroxyl groups. Several strategies have been developed / attempted over the last several decades leading to the synthesis of naturally occurring phosphoinositols, their analogs and cyclitol derivatives. Of late, myo-inositol 1,3-acetals, which can be obtained by the reductive cleavage of myo-inositol orthoesters have emerged as early intermediates for the synthesis of phosphorylated and other inositol derivatives. This mini-review is an attempt to illustrate the economy and convenience of using myo-inositol 1,3-acetals as early intermediates during syntheses from myo-inositol.
      Graphical abstract image Highlights

      PubDate: 2014-09-04T22:13:59Z
       
  • Structural characterization of
           (1→2)-β-xylose-(1→3)-α-arabinose-containing
           oligosaccharide products of extracted switchgrass (Panicum virgatum, L.)
           xylan after exhaustive enzymatic treatment with α-arabinofuranosidase
           and β-endo-xylanase
    • Abstract: Publication date: Available online 19 August 2014
      Source:Carbohydrate Research
      Author(s): Michael J. Bowman , Bruce S. Dien , Karl E. Vermillion , Jeffrey A. Mertens
      Switchgrass (Panicum virgatum, L.) is a potential dedicated biomass crop for use in biocatalytic conversion systems to biofuels. Nearly 30% of switchgrass cell wall material is xylan. The complete depolymerization of xylan is desirable both as an additional carbon source for microbial fermentation and to reduce inhibitory effects xylooligomers may have on cellulolytic glycoside hydrolase enzymes. To identify structural features of switchgrass xylan that are not distinguishable by mass spectrometry alone, a α-arabinofuranosidase enzyme was used to remove the arabinose side chains from alkali-extracted switchgrass xylan from three cultivars with simultaneous hydrolysis by β-endo-xylanase to enrich for oligosaccharide products with extended branching. The two most abundant enzymatic digestion products were separated and characterized by LC-MS n , linkage analysis, and NMR. These two oligosaccharides were present in all three switchgrass cultivars and found to contain (1→2)-β-xylose-(1→3)-α-arabinose side chains, a linkage not previously reported in switchgrass.
      Graphical abstract image Highlights

      PubDate: 2014-09-04T22:13:59Z
       
  • Bioactive hemicelluloses alkali-extracted from Fallopia sachalinensis
           leaves
    • Abstract: Publication date: Available online 19 August 2014
      Source:Carbohydrate Research
      Author(s): Zuzana Košťálová , Zdenka Hromádková , Berit Smestad Paulsen , Anna Ebringerová
      Fallopia sachalinensis, regarded as an invasive plant in Europe and designated for disposal, is traditionally used in Japan and China as herbal medicine. Attempted for valorization of the leaves, this paper reports on two proteins-free polysaccharide fractions, a neutral (FS-5A) and an acidic (FS-5B) one, obtained via alkali extraction and consecutive purification. Both fractions were characterized by chemical, molecular, structural and bioactive properties. FTIR and 1D/2D NMR analyses revealed that FS-5A consisted of afucogalactoxyloglucan, whereas, glucuronoxylan was the major hemicellulose in FS-5B accompanied with low proportions of fucosylated xyloglucan and pectic RG-I. Both hemicellulose fractions exhibited significant immunostimulating activity in the complement-fixation test and the later had noticeable DPPH radical-scavenging ability. The results completed information about neutral and acidic bioactive polysaccharide components present in the leaves of F. sachalinensis.
      Graphical abstract image Highlights

      PubDate: 2014-09-04T22:13:59Z
       
  • 1H NMR analysis of the lactose/β-galactosidase-derived
           galacto-oligosaccharide components of Vivinal® GOS up to DP5
    • Abstract: Publication date: Available online 1 September 2014
      Source:Carbohydrate Research
      Author(s): Sander S. van Leeuwen , Bas J.H. Kuipers , Lubbert Dijkhuizen , Johannis P. Kamerling
      Vivinal® GOS is a galacto-oligosaccharide (GOS) product, prepared from lactose by incubation with Bacillus circulans β-galactosidase (EC 3.2.1.23). This complex mixture of saccharides with degree of polymerization (DP) between 1 and 8 is generally applied in infant nutrition. Here, a detailed structural description of the commercial product up to the DP5 level is given. First, Vivinal® GOS was subjected to DP analysis using HPLC-SEC (Rezex RSO-01 oligosaccharide Ag+ column) and 1H NMR analysis. Then, the product was fractionated on Bio-Gel P-2, and the obtained fractions were pooled according to DP, as indicated by MALDI-TOF-MS analysis. Finally, fractions of single DP, as well as their subfractions obtained by HPAEC-PAD on CarboPac PA-1, were analyzed by 1D/2D 1H/13C NMR spectroscopy and linkage analysis. In total, over 40 structures, providing a structural coverage of over 99% of the product, have been characterized. Detailed 1H and 13C NMR data, as well as G.U. values (glucose units; malto-oligosaccharide ladder) on CarboPac PA-1 of all oligosaccharides are included.
      Graphical abstract image

      PubDate: 2014-09-04T22:13:59Z
       
  • Development of a 1H NMR structural-reporter-group concept for the analysis
           of prebiotic galacto-oligosaccharides of the
           [β-D-Galp-(1→x)]n-D-Glcp type
    • Abstract: Publication date: Available online 1 September 2014
      Source:Carbohydrate Research
      Author(s): Sander S. van Leeuwen , Bas J.H. Kuipers , Lubbert Dijkhuizen , Johannis P. Kamerling
      Some β-galactosidases (EC 3.2.1.23) are capable of producing mixtures of linear and branched galacto-oligosaccharides (GOS) with various types of glycosidic linkages [degree of polymerization (DP) 2-8; mainly GalnGlc] when incubated under specific conditions with lactose. These products are generally applied in infant formula. However, for most galacto-oligosaccharide products only major components (low DP) or linkage patterns have been described. To build up a library of 1H and 13C NMR data, a detailed NMR study on commercially available GOS di- and trisaccharides, and some larger GOS oligosaccharides was carried out. Based on the fully assigned 1H and 13C chemical shifts of these model compounds, a 1H NMR structural-reporter-group concept was formulated to function as a tool in the structural analysis of single GOS components and GOS mixtures.
      Graphical abstract image

      PubDate: 2014-09-04T22:13:59Z
       
  • A new, quick, highly sensitive ultramicro-analysis method for the
           identification of fructose removed from fructofuranosyl-containing
           gluco-oligosaccharides by ESI-CID-MS/MS
    • Abstract: Publication date: Available online 2 September 2014
      Source:Carbohydrate Research
      Author(s): Hong-Tao Zhang , Li Zhu , Shuang Zhang , Xiao-Bei Zhan , Chi-Chung Lin
      An efficient, highly sensitive and ultramicroscale analytical method for the identification of fructose removed from fructofuranosyl-containing gluco-oligosaccharides, including malto-oligosyl fructofuranosides and oligomeric (1→2)-α-D-glucopyranosyl-(1→2)-β-D-fructofuranosides by ESI-CID-MS/MS has been developed with proven applications far superior to the existing method using NMR. With the established principle of diagnostic fragmentation by ESI-CID-MS/MS, the terminal saccharide (either glucose or fructose) can be readily and unambiguously determined at high sensitivity without tedious derivatization process. Detection of the A-type fragmentation 0,4Ah type ion, and 0,2A type ion are useful as a diagnostic fragmentation tool to identify whether fructose terminal is removed from oligosaccharides. It will facilitate the efficient production of suitable oligosaccharide microarrays crucial for studies on carbohydrate-protein interaction in seeking functional carbohydrates.
      Graphical abstract image Highlights Identification the removal of fructose from fructofuranosyl-containing glucooligosaccharides based on the regular pattern of negative ESI-CID-MS/MS product-ion

      PubDate: 2014-09-04T22:13:59Z
       
  • Editorial board
    • Abstract: Publication date: 19 September 2014
      Source:Carbohydrate Research, Volume 396




      PubDate: 2014-09-04T22:13:59Z
       
  • Graphical contents list
    • Abstract: Publication date: 19 September 2014
      Source:Carbohydrate Research, Volume 396




      PubDate: 2014-09-04T22:13:59Z
       
  • Affinity of monoclonal antibodies for Globo-series glycans
    • Abstract: Publication date: 9 October 2014
      Source:Carbohydrate Research, Volume 397
      Author(s): Chelcie H. Eller , Guangbin Yang , Ouathek Ouerfelli , Ronald T. Raines
      Globo-series glycans are human cell-surface carbohydrates that include stem-cell marker SSEA-4 and cancer-cell antigen Globo H. These two hexasaccharides differ only in their terminal saccharide: N-acetylneuraminic acid in SSEA-4 and l-fucose in Globo H. Herein, we evaluated the affinity of the monoclonal antibodies α-SSEA-4 and α-GH for the glycans SSEA-4 and Globo H. Using fluorescence polarization, we find that the two monoclonal antibodies have affinity for their cognate glycan in the low nanomolar range, and have negligible affinity for the non-cognate glycan. Using surface plasmon resonance, we find that each cognate affinity is ∼20-fold greater if the glycan is immobilized on a surface rather than free in solution. We conclude that the terminal saccharide plays a dominant role in the ability of monoclonal antibodies to recognize these Globo-series glycans and that the extraordinary specificity of these antibodies supports their use for identifying and sorting stem-cells (α-SSEA-4) and as an agent in cancer immunotherapy (α-GH).
      Graphical abstract image

      PubDate: 2014-09-04T22:13:59Z
       
  • Some Findings in Transgalactosylations Employing Modified Donor Substrates
    • Abstract: Publication date: Available online 18 August 2014
      Source:Carbohydrate Research
      Author(s): Lars Kröger , Joachim Thiem
      The scope of transgalactosylation with β-galactosidase (bovine testis) was studied employing a series of modified donor substrates based on p-nitrophenyl β-D-galactopyranoside and as uniform acceptor allyl 2-N-acetamido-2-deoxy-α-D-galactopyranoside. Structurally diverse donor molecules were recognized by the enzyme and led to novel disaccharide components, yet an excessive structural distortion was not accepted.
      Graphical abstract image

      PubDate: 2014-08-18T21:00:02Z
       
  • Facile nanofibrillation of chitin derivatives by gas bubbling and
           ultrasonic treatments in water
    • Abstract: Publication date: Available online 18 August 2014
      Source:Carbohydrate Research
      Author(s): Kohei Tanaka , Kazuya Yamamoto , Jun-ichi Kadokawa
      In this paper, we report that nanofiber network structures were constructed from chitin derivatives by gas bubbling and ultrasonic treatments in water. When chitin was first subjected to N2 gas bubbling with ultrasonication in water, the SEM images of the product showed nanofiber network morphology. However, nanofiber network was not re-constructed by the same N2 gas bubbling and ultrasonic treatments after agglomeration. We then have paid attention to an amidine group to provide the agglomeration-nanofibrillation behavior of chitin derivatives. An amidinated chitin was synthesized by the reaction of the amino groups in a partially deacetylated chitin with N,N-dimethylacetamide dimethyl acetal, which was subjected to CO2 gas bubbling and ultrasonic treatments in water to convert into an amidinium chitin by protonation. The SEM images of the product clearly showed nanofiber network morphology. We further examined re-nanofibrillation of the agglomerated material, which was obtained by mixing the nanofibrillated amidinium chitin with water, followed by drying under reduced pressure. Consequently, the material was re-nanofibrillated by N2 gas bubbling with ultrasonication in water owing to electrostatic repulsion between the amidinium groups. Furthermore, deprotonation of the amidinium chitin and re-protonation of the resulting amidinated chitin were conducted by alkaline treatment and CO2 gas bubbling-ultrasonic treatments, respectively. The material showed the agglomeration-nanofibrillation behavior during the processes.
      Graphical abstract image

      PubDate: 2014-08-18T21:00:02Z
       
  • D-Glucose Derived Novel Gemini Surfactants: Synthesis and Study of Their
           Surface Properties, Interaction with DNA, and Cytotoxicity
    • Abstract: Publication date: Available online 14 August 2014
      Source:Carbohydrate Research
      Author(s): Vikash Kumar , Amrita Chatterjee , Nupur Kumar , Anasuya Ganguly , Indranil Chakraborty , Mainak Banerjee
      Four new D-glucose derived m-s-m type gemini surfactants with variable spacer and tail length have been synthesized by a simple and efficient synthetic methodology utilizing the free C-3 hydroxy group of diisopropylidene glucose. The synthetic route to these gemini surfactants with a quaternary ammonium group as polar head group involves a sequence of simple reactions including alkylation, imine formation, quaternization of amine etc. The surface properties of the new geminis were evaluated by surface tension and conductivity measurements. These gemini surfactants showed low cytotoxicity by MTT assay on HeLa cell line. The DNA binding capabilities of these surfactants were determined by agarose gel electrophoresis, fluorescence titration and DLS experiments. The preliminary studies by agarose gel electrophoresis indicated chain length dependent DNA binding abilities, further supported by ethidium bromide exclusion experiments. Two of the D-glucose derived gemini surfactants showed effective binding with pET-28a plasmid DNA (pDNA) at relatively low N/P ratio (i. e. cationic nitrogen/DNA phosphate molar ratio).
      Graphical abstract image Highlights

      PubDate: 2014-08-14T20:53:24Z
       
  • Structure and gene cluster of the O-antigen of Escherichia coli O68
    • Abstract: Publication date: Available online 12 August 2014
      Source:Carbohydrate Research
      Author(s): Lingyan Jiang , Andrei V. Perepelov , Andrei V. Filatov , Bin Liu , Alexander S. Shashkov , Sof’ya N. Senchenkova , Lei Wang , Yuriy A. Knirel
      The O-polysaccharide (O-antigen) of Escherichia coli O68 was studied by sugar analysis, partial solvolysis with anhydrous trifluoroacetic acid, and 1D and 2D 1H and 13C NMR spectroscopy. The following structure of the branched heptasaccharide repeating unit was established: The O-antigen gene cluster of E. coli O68 was sequenced. The gene functions were tentatively assigned by comparison with sequences in the available databases and found to be in full agreement with the O-antigen structure.
      Graphical abstract image

      PubDate: 2014-08-14T20:53:24Z
       
  • Synthesis, micellization and lectin binding of new glycosurfactants
    • Abstract: Publication date: Available online 5 August 2014
      Source:Carbohydrate Research
      Author(s): Alexandre G. Dal Bó , Valdir Soldi , Fernando C. Giacomelli , Christophe Travelet , Redouane Borsali , Sébastien Fort
      Here we report the preparation and physico-chemical characterization of carbohydrate-decorated micelles and their interaction with lectins. A library of biosourced amphiphiles was prepared by copper-catalyzed azide-alkyne cycloaddition (CuAAC) between alkynyl sugars (lactose, N-acetyl-D-glucosamine) and azido-functionalized poly(ethylene glycol) esters (N3- PEG900-decanoate (C10) and -dodecanoate (C12)). In water, these glycoconjugates self-assemble into micelles of homogeneous nanometric size (11 nm) as evidenced by scattering techniques (DLS for light, and SAXS for X-ray). A comparative study with previously synthesized octadecanoate counterparts pointed out that that nature of the fatty acid has no significant influence on the particle size but only affects their compactness. These findings are in favor of a possible bulk preparation from lipid mixtures such as those encountered in renewable vegetable oils. The presence of the carbohydrate epitopes on the surface of the micelles and their bioavailability for lectin targeting were also evidenced by light scattering measurements using wheat germ agglutinin (WGA) and peanut (Arachis Hypogaea) (PNA) lectins, supporting possible application as targeted drug nanocarriers.
      Graphical abstract image Highlights

      PubDate: 2014-08-10T20:44:14Z
       
  • Complex and mixture of β-cyclodextrin with diazepam characterised by
           1H NMR and atom-atom potential methods
    • Abstract: Publication date: Available online 7 August 2014
      Source:Carbohydrate Research
      Author(s): A. Pajzderska , J. Mielcarek , J. Wąsicki
      Inclusion complex of β-cyclodextrin with diazepam and a physical mixture of these components were studied by solid-state 1H NMR. The activation barrier for reorientation of the methyl group in the diazepam molecule was found not changed by complex formation with β-cyclodextrin. The complex formation resulted in a decrease in the number of water molecules and affected the relaxation time of β-cyclodextrin. By the atom-atom potential method the most probable configuration of the diazepam molecule inside β-cyclodextrin cavity was proposed.
      Graphical abstract image Highlights

      PubDate: 2014-08-10T20:44:14Z
       
  • Conformationally restricted
           3,5-O-(di-tert-butylsilylene)-d-galactofuranosyl thioglycoside donor for
           1,2-cis α-d-galactofuranosylation
    • Abstract: Publication date: Available online 7 August 2014
      Source:Carbohydrate Research
      Author(s): Mariano J. Tilve , Carola Gallo-Rodriguez
      A conformationally restricted 2-O-benzyl-3,5-O-di-tert-butylsilylene-β-D-thiogalactofuranoside donor was prepared from benzyl α-D-galactofuranoside and its donor capability was studied for stereoselective 1,2-cis α-d-galactofuranosylation. An unusual chemical behavior on benzylation and hydrogenolysis reactions was observed after the introduction of the 3,5-O-di-tert-butylsilylene protecting group into the galactofuranosyl moiety. The influence of the solvent, temperature and activating system was evaluated. The NIS/AgOTf system, widely used in 1,2-cis β-arabinofuranosylation, was not satisfactory enough for 1,2-cis galactofuranosylation. However, moderate to high α-selectivity was obtained with all the acceptors employed when used p-NO2PhSCl/AgOTf as a promoting system, in CH2Cl2 at -78 °C. The order of the addition of the reactants (premixing or preactivation) did not affect substantially the stereochemical course of the glycosylation reaction. The α-d-Galf-(1→6)-d-Man linkage was achieved with complete diastereoselectivity by preactivation of the conformationally constrained thioglycoside donor.
      Graphical abstract image Highlights

      PubDate: 2014-08-10T20:44:14Z
       
  • In(III) triflate-catalyzed detritylation and glycosylation by solvent-free
           ball milling
    • Abstract: Publication date: Available online 10 August 2014
      Source:Carbohydrate Research
      Author(s): Vajinder Kumar , Narender Yadav , K.P. Ravindranathan Kartha
      A highly efficient In(III) triflate-assisted method for the detritylation of O-trityl derivatives of carbohydrates, phenols and alcohols by solvent-free mechanochemical method is described. In the case of carbohydrates, further reaction in the presence of an acceptor sugar leads to highly efficient glycosylation in the same pot resulting in the formation of the desired glycoside-product in very high yields. The method was applied successfully to the synthesis of a combinatorial library of galactose-based (1,6)-linked cyclohexa-, hepta- and octasaccharides on gram scale.
      Graphical abstract image

      PubDate: 2014-08-10T20:44:14Z
       
  • Side reactions with 2,2,2-trichloroethoxysulfates during the synthesis of
           glycans
    • Abstract: Publication date: 19 September 2014
      Source:Carbohydrate Research, Volume 396
      Author(s): Kenya Matsushita , Yuta Sato , Shinji Funamoto , Jun-ichi Tamura
      Protected sulfate groups may be used as an alternative tool to provide sulfate esters at hydroxyl and amino groups, particularly on complex glycans. We examined 2,2,2-trichloroethoxysulfation at the mono-, di-, and trihydroxyl groups of saccharide moieties to show regioselective sulfation. We found some side reactions including inter- and intramolecular nucleophilic reactions with 2,2,2-trichloroethoxysulfates.
      Graphical abstract image

      PubDate: 2014-08-10T20:44:14Z
       
  • Preparation, characterisation and bioactivity evaluation of the inclusion
           complex formed between picoplatin and γ-cyclodextrin
    • Abstract: Publication date: Available online 1 August 2014
      Source:Carbohydrate Research
      Author(s): Jian-Qiang Zhang , Ke Li , Yan-Wei Cong , Shao-Ping Pu , Hong-You Zhu , Xiao-Guang Xie , Yi Jin , Jun Lin
      The inclusion complex of picoplatin with γ-cyclodextrin (γ-CD) was prepared and characterised by different analytical methods, including NMR, FTIR, TGA, phase solubility as well as SEM. All of these approaches indicated that picoplatin was able to form an inclusion complex with γ-CD, and that the picoplatin/γ-CD inclusion compounds exhibited different spectroscopic features and properties from free picoplatin. The stoichiometry of the complex was 1:1; the pyridine group of picoplatin was deeply inserted into the cavity of γ-CD and the amine platinum group of picoplatin was near the narrower rim of γ-CD. The calculated apparent stability constant of the complex was 10,318 M-1. Moreover, the water solubility of picoplatin was significantly improved, according to phase-solubility studies. The complex maintained its anticancer activity, as shown by an in vitro cell-survival assay on A549 and MCF-7 cancer cell lines. All of these results showed that inclusion complexation may be a promising strategy to design a novel formulation of picoplatin as an anticancer therapy.
      Graphical abstract image Highlights

      PubDate: 2014-08-01T20:01:10Z
       
  • Sweet graphene I: toward hydrophilic graphene nanosheets via click
           grafting alkyne-saccharides onto azide-functionalized graphene oxide
    • Abstract: Publication date: 19 September 2014
      Source:Carbohydrate Research, Volume 396
      Author(s): Mina Namvari , Hassan Namazi
      Water-soluble graphene nanosheets (GNS) were fabricated via functionalization of graphene oxide (GO) with mono and disaccharides on the basal plane and edges using Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition of azides and terminal alkynes (Click chemistry). To graft saccharides onto the plane of GO, it was reacted with sodium azide to introduce azide groups on the plane. Then, it was treated with alkyne-modified glucose, mannose, galactose, and maltose. In the next approach, we attached 1,3-diazideoprop-2-ol onto the edges of GO and it was subsequently clicked with alkyne-glucose. The products were analyzed by Fourier-transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy, thermogravimetric analysis (TGA), and X-ray diffraction spectrometry. FTIR and TGA results showed both sugar-grafted GO sheets were reduced by sodium ascorbate during click-coupling reaction which is an advantage for this reaction. Besides, glycoside-grafted GNS were easily dispersed in water and stable for two weeks.
      Graphical abstract image

      PubDate: 2014-08-01T20:01:10Z
       
  • The use of O-trifluoroacetyl protection and profound influence of the
           nature of glycosyl acceptor in benzyl-free arabinofuranosylation
    • Abstract: Publication date: 19 September 2014
      Source:Carbohydrate Research, Volume 396
      Author(s): Polina I. Abronina , Ksenia G. Fedina , Nikita M. Podvalnyy , Alexander I. Zinin , Alexander O. Chizhov , Nikolay N. Kondakov , Vladimir I. Torgov , Leonid O. Kononov
      The influence of O-trifluoroacetyl (TFA) groups at different positions of thioglycoside glycosyl donors on stereoselectivity of α-arabinofuranosylation leading to corresponding disaccharides was studied. It was shown that TFA group in thioglycoside glycosyl donors, when combined with 2-O-(triisopropylsilyl) (TIPS) non-participating group, may be regarded as an electron-withdrawing protecting group that may enhance 1,2-cis-selectivity in arabinofuranosylation, the results strongly depending on the nature of glycosyl acceptor. The reactivities of the glycosyl donors were compared with those of a similar thioglycoside with O-pentafluoropropionyl groups and the known phenyl 3,5-O-(di-tert-butylsilylene)-1-thio-α-d-arabinofuranosides with 2-O-TIPS and 2-O-benzyl groups. The ‘matching’ in the donor–acceptor combination was found to be critical for achieving both high reactivity of glycosyl donor and β-stereoselectivity of arabinofuranosylation. The use of glycosyl donors with TFA and silyl protection may be useful in the realization of the benzyl-free approach to oligoarabinofuranosides with azido group in aglycon—convenient building blocks for the preparation of neoglycoconjugates.
      Graphical abstract image

      PubDate: 2014-08-01T20:01:10Z
       
  • Does intramolecular hydrogen bond play a key role in the stereochemistry
           of α- and β-d-glucose?
    • Abstract: Publication date: 19 September 2014
      Source:Carbohydrate Research, Volume 396
      Author(s): Josué M. Silla , Rodrigo A. Cormanich , Roberto Rittner , Matheus P. Freitas
      Four α- and three β-isomers of the d-glucose were optimized in gas phase using ab initio (MP2) and DFT (ωB97X-D) methods, both using the aug-cc-pVDZ basis set. While earlier works suggest that the orientation of the hydroxyl groups is due to intramolecular hydrogen bonds (H-bonds), the present study reveals that most H-bonds forming five-membered rings are either weak or even do not exist. The quantum theory of atoms in molecules (QTAIM) analysis showed only a few cases of H-bond in d-glucose, particularly for those H-bonds forming six-membered rings, while the non-covalent interactions (NCI) analysis indicated that most intramolecular H-bonds are not strong enough to justify the counter-clockwise arrangement of the OH⋯O chains. Natural bond orbital analysis supported the findings obtained from QTAIM and NCI analyses and indicated that the anomeric effect for d-glucose in the gas phase is governed by a balance of steric, electrostatic, and hyperconjugative interactions.
      Graphical abstract image

      PubDate: 2014-08-01T20:01:10Z
       
  • Simple synthesis of glycosylthiols and thioglycosides by rearrangement of
           O-glycosyl thionocarbamates
    • Abstract: Publication date: Available online 9 July 2014
      Source:Carbohydrate Research
      Author(s): A. Kasprzycka , R. Komor , G. Pastuch Gawołek , W. Szeja
      The synthesis of thioglycosides has been achieved in a high yielding process employing thionocarbamates prepared from protected reducing sugars and N-alkyl isothiocyanate in the presence of a non-nucleophilic base (K2CO3). In the key step of the synthesis, thionocarbamates were treated with Lewis acid (TMSOTf) to give O,S-rearrangement products that were applied to the synthesis of both anomers of heteroaryl thioglycosides.
      Graphical abstract image Highlights

      PubDate: 2014-07-27T19:35:12Z
       
  • Highly stereoselective synthesis of C-vinyl pyranosides via a Pd-mediated
           cycloetherification of 1-acetoxy-2,3-dideoxy-oct-2-enitols
    • Abstract: Publication date: Available online 16 July 2014
      Source:Carbohydrate Research
      Author(s): Ernest G. Nolen , Vivian C. Ezeh , Matthew J. Feeney
      Oct-2-enitols undergo a Pd°-mediated cyclization to produce C-vinyl α-gluco- and α-galactopyranosides, and C-vinyl β-mannopyranoside in good yield and with high stereoselectivity. While substrate control demonstrates a clear stereochemical preference during cyclization, the α- and β-epimeric ratios are enhanced by double diastereoselection using the (S,S) or (R,R)-DACH ligands.
      Graphical abstract image Highlights

      PubDate: 2014-07-27T19:35:12Z
       
  • Useful approach to the synthesis of aryl thio- and selenoglycosides in the
           presence of rongalite
    • Abstract: Publication date: Available online 21 July 2014
      Source:Carbohydrate Research
      Author(s): Cheerladinne Venkateswarlu , Vibha Gautam , Srinivasan Chandrasekaran
      A simple, mild and cost effective methodology has been developed for the synthesis of aryl thio-and selenoglycosides from glycosyl halides and diaryl dichalcogenides. Diaryl dichalcogenides undergo reductive cleavage in the presence of rongalite (HOCH2SO2Na) to generate chalcogenate anion in situ followed by reaction with glycosyl halides to furnish the corresponding aryl thio- and selenoglycosides in excellent yields. Using this protocol, synthesis of 4-methyl-7-thioumbelliferyl-β-D-cellobioside (MUS-CB), a fluorescent non-hydrolyzable substrate analogue for cellulases has been achieved.
      Graphical abstract image

      PubDate: 2014-07-27T19:35:12Z
       
  • A simplified procedure for gram-scale production of sialylglycopeptide
           (SGP) from egg yolks and subsequent semi-synthesis of Man3GlcNAc oxazoline
           
    • Abstract: Publication date: Available online 27 July 2014
      Source:Carbohydrate Research
      Author(s): Bingyang Sun , Wenzheng Bao , Xiaobo Tian , Mingjing Li , Hong Liu , Jinhua Dong , Wei Huang
      Heterogeneity of glycan structures in native glycoconjugates always hampers precise studies on carbohydrate-involved biological functions. To construct homogeneous glycoconjugates from natural resource of homogeneous glycans is therefore a practical approach to solve this problem. We report here an optimized procedure for gram-scale production of sialoglycopeptide (SGP) containing a disialyl biantennary complex-type N-glycan from egg yolks. Our new procedure simplified the extraction process by treating the egg yolk powder with 40% acetone, avoiding massive emulsification, high-speed centrifugation, and sophisticated chromatography in reported methods. Subsequent semi-synthesis of the N-glycan core Man3GlcNAc oxazoline from SGP was accomplished for the first-time via glyco-trimming and successive oxazoline formation. This efficient semi-synthesis provides an alternative to the pure chemical approach that involves multi-step total synthesis and facilitates the application of Endo-glycosidase-enabled chemoenzymatic synthesis of various homogeneous glycoconjugates.
      Graphical abstract image Highlights

      PubDate: 2014-07-27T19:35:12Z
       
 
 
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