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  Subjects -> CHEMISTRY (Total: 825 journals)
    - ANALYTICAL CHEMISTRY (47 journals)
    - CHEMISTRY (575 journals)
    - CRYSTALLOGRAPHY (22 journals)
    - ELECTROCHEMISTRY (26 journals)
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CHEMISTRY (575 journals)                  1 2 3 4 5 6 | Last

2D Materials     Hybrid Journal   (Followers: 4)
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: 26)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 14)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 9)
ACS Macro Letters     Full-text available via subscription   (Followers: 20)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 25)
ACS Nano     Full-text available via subscription   (Followers: 368)
ACS Photonics     Full-text available via subscription   (Followers: 6)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 11)
Acta Chemica Iasi     Open Access  
Acta Chimica Sinica     Full-text available via subscription  
Acta Chimica Slovaca     Open Access   (Followers: 6)
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: 5)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 4)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 5)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 10)
Advanced Functional Materials     Hybrid Journal   (Followers: 39)
Advanced Science Focus     Free  
Advances in Chemical Engineering and Science     Open Access   (Followers: 23)
Advances in Chemical Science     Open Access   (Followers: 9)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 15)
Advances in Drug Research     Full-text available via subscription   (Followers: 17)
Advances in Enzyme Research     Open Access  
Advances in Fluorine Science     Full-text available via subscription   (Followers: 7)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 13)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 16)
Advances in Nanoparticles     Open Access   (Followers: 12)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 9)
Advances in Polymer Science     Hybrid Journal   (Followers: 39)
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: 5)
Afrique Science : Revue Internationale des Sciences et Technologie     Open Access   (Followers: 1)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 1)
Alchemy     Open Access   (Followers: 3)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 5)
AMB Express     Open Access  
Ambix     Hybrid Journal   (Followers: 2)
American Journal of Applied Sciences     Open Access   (Followers: 32)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 223)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 12)
American Journal of Chemistry     Open Access   (Followers: 18)
American Journal of Plant Physiology     Open Access   (Followers: 10)
American Mineralogist     Full-text available via subscription   (Followers: 7)
Analyst     Full-text available via subscription   (Followers: 38)
Angewandte Chemie     Hybrid Journal   (Followers: 18)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 277)
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: 5)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 11)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 12)
Anti-Infective Agents     Hybrid Journal   (Followers: 1)
Antiviral Chemistry and Chemotherapy     Full-text available via subscription  
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 4)
Applied Spectroscopy     Full-text available via subscription   (Followers: 13)
Applied Surface Science     Hybrid Journal   (Followers: 21)
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: 2)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 6)
Biochemistry     Full-text available via subscription   (Followers: 283)
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)
Bioinspired Materials     Open Access  
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: 14)
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: 2)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 13)
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: 11)
Carbon     Hybrid Journal   (Followers: 55)
Catalysis for Sustainable Energy     Open Access   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 6)

        1 2 3 4 5 6 | Last

Journal Cover   Carbohydrate Research
  [SJR: 0.654]   [H-I: 83]   [13 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0008-6215 - ISSN (Online) 0008-6215
   Published by Elsevier Homepage  [2586 journals]
  • Reactivity of d-fructose and d-xylose in acidic media in homogeneous
           phases
    • Abstract: Publication date: 29 May 2015
      Source:Carbohydrate Research, Volume 409
      Author(s): Maxime B. Fusaro , Vincent Chagnault , Denis Postel
      Chemistry development of renewable resources is a real challenge. Carbohydrates from biomass are complex and their use as substitutes for fossil materials remains difficult (European involvement on the incorporation of 20% raw material of plant origin in 2020). Most of the time, the transformation of these polyhydroxylated structures are carried out in acidic conditions. Recent reviews on this subject describe homogeneous catalytic transformations of pentoses, specifically toward furfural, and also the transformation of biomass-derived sugars in heterogeneous conditions. To complete these informations, the objective of this review is to give an overview of the structural variety described during the treatment of two monosaccharides (d-Fructose and d-xylose) in acidic conditions in homogeneous phases. The reaction mechanisms being not always determined with certainty, we will also provide a brief state of the art regarding this.
      Graphical abstract image

      PubDate: 2015-04-16T02:58:00Z
       
  • Structural elucidation of the outer core tetrasaccharide isolated from the
           LPS of Rhizobium leguminosarum bv. trifolii strain 24
    • Abstract: Publication date: 29 May 2015
      Source:Carbohydrate Research, Volume 409
      Author(s): Anna Turska-Szewczuk , Ryszard Russa , Magdalena A. Karaś , Witold Danikiewicz , Grzegorz Spólnik
      The outer core oligosaccharide (OS) was isolated from the lipopolysaccharide (LPS) of Rhizobium leguminosarum bv. trifolii strain 24 after Smith degradation and then studied by sugar and methylation analyses along with NMR and mass spectrometry methods. Negative-ion electrospray (ESI-MS) mass spectrum showed two molecular ions at m/z 686.3 and 728.3, which corresponded to the core OS having the composition Rha2QuiNAcKdh. The mass difference between both ions indicated that the higher molecule mass represented the mono O-acetylated variant of the OS. The sequence of the oligosaccharide was reflected in CID MS/MS spectra. In turn, NMR spectroscopy confirmed the composition and glycosylation pattern of the core OS and provided additional evidence on its structure. 2D NMR experiments revealed that the terminal Rhap is acetylated at position O-2. Moreover, 3-deoxyheptulosonic acid (Kdh), which was detected at the reducing terminus of the OS, was evidently derived from the Kdo as a result of Smith degradation. In addition, the higher intensity of signals for a six-membered pyranose ring of Kdhp over 2,7-anh-Kdhf seemed to indicate prevalence of this form of the sugar in the OS-derived species. Based on the data obtained, the following structure of the outer core tetrasaccharide, which probably links the O-chain polysaccharide to the inner core in the LPS of R. leguminosarum bv. trifolii strain 24, was established:
      Graphical abstract image

      PubDate: 2015-04-16T02:58:00Z
       
  • Efficient Regioselective O3-Monodesilylation by Hydrochloric Acid in
           Cyclodextrins
    • Abstract: Publication date: Available online 16 April 2015
      Source:Carbohydrate Research
      Author(s): Jiamin Gu , Tong Chen , Qifang Wang , Tieyu Chen , Chang-Chun Ling
      An efficient O3-monodesilylation method has been developed for the derivatization of per-3-O-silylated cyclodextrin (CD) derivatives. Using hydrochloric acid as a reagent, the O3-monodesilylation was found to be regioselective, mild, practical and general as it can be can be applied to all α-, β- and γ-CDs. The advantage of the methodology is that the acid-catalyzed O3-desilylation can be carried out in a stepwise manner so that different types of functional groups can be introduced to a CD molecule at different stage of the O3-desilylations. This makes the current methodology flexible and versatile. This current methodology constitutes one of the few methodologies available for the regioselective modification of CDs at the secondary face.
      Graphical abstract image

      PubDate: 2015-04-16T02:58:00Z
       
  • Comparing substrate specificity of two UDP-sugar Pyrophosphorylases and
           Efficient One-pot Enzymatic Synthesis of UDP-GlcA and UDP-GalA
    • Abstract: Publication date: Available online 16 April 2015
      Source:Carbohydrate Research
      Author(s): Yuxi Guo , Junqiang Fang , Tiehai Li , Xu Li , Cheng Ma , Xuan Wang , Peng G. Wang , Lei Li
      Uridine 5’-diphosphate-glucuronic acid (UDP-GlcA) and UDP-galacturonic acid (UDP-GalA), the unique carboxylic acid-formed sugar nucleotides, are key precursors involved in the biosynthesis of numerous cell components. Limited availability of those components has been hindering the development of efficient ways towards facile synthesis of bioactive glycans such as glycosaminoglycans. In current study, we biochemically characterized two UDP-sugar pyrophosphorylases from Arabidopsis thaliana (AtUSP) and Bifidobacterium infantis ATCC15697 (BiUSP), and compared their activities towards a panel of sugar-1-phosphates and derivatives. Both enzymes showed significant pyrophosphorylation activities towards GlcA-1-phosphate, and AtUSP also exhibited comparable activity towards GalA-1-phosphate. By combining with monosaccharide-1-phosphate kinases, we have developed an efficient and facile one-pot three-enzyme approach to quickly obtain hundreds milligrams of UDP-GlcA and UDP-GalA.
      Graphical abstract image

      PubDate: 2015-04-16T02:58:00Z
       
  • Synthesis and antimicrobial activity of 6-triazolo-6-deoxy eugenol
           glucosides
    • Abstract: Publication date: Available online 13 April 2015
      Source:Carbohydrate Research
      Author(s): Thiago Belarmino de Souza , Paulo Otávio Botelho Raimundo , Saulo Fernandes Andrade , Taciane Maira Magalhães Hipólito , Naiara Chaves Silva , Amanda Latercia Tranches Dias , Masaharu Ikegaki , Raissa Prado Rocha , Luiz Felipe Leomil Coelho , Marcia Paranho Veloso , Diogo Teixeira Carvalho , Danielle Ferreira Dias
      A new series of 1,2,3-triazole eugenol glucosides were synthesized. The new compound structures were confirmed by MS, 1H-NMR and 13C-NMR. All of the synthesized compounds were screened for antimicrobial and cytotoxic activity. Five compounds exerted significant activity against the Gram-negative bacteria Salmonella typhimurium with low IC50 values (49.73-68.53 μΜ), and seven compounds were active against the Gram-positive bacteria Micrococcus luteus (42.89-210.94 μM). In vitro cytotoxicity on mouse spleen cells was also evaluated. One compound bearing a phenyl substituent at the triazole ring showed good activity against Salmonella typhimurium (49.73 μM) and low toxicity to normal cells (CC50 = 157.83 μM). Thus, the compounds herein can be considered for further modification for improving their antibacterial activity or obtaining novel antibacterial drug candidates.
      Graphical abstract image

      PubDate: 2015-04-16T02:58:00Z
       
  • Isolation and characterization of inulin with a high degree of
           polymerization from roots of Stevia rebaudiana (Bert.) Bertoni
    • Abstract: Publication date: Available online 11 April 2015
      Source:Carbohydrate Research
      Author(s): Sheila M.S. Lopes , Gabriela Krausová , Vojtěch Rada , José E. Gonçalves , Regina A.C. Gonçalves , Arildo J.B. de Oliveira
      The polysaccharide inulin has great importance in the food and pharmaceutical industries. The degree of polymerization (DP) of inulin influences important properties, such as, solubility, thermal stability, sweetness power and prebiotic activity. Molecules with a high degree of polymerization are obtained through physical techniques for enrichment of the inulin chains because they are not commonly obtained from plants extract. Gas Chromatography Mass Spectrometry and 1H Nuclear Magnetic Resonance analysis showed that inulin from Stevia rebaudiana roots has a degree of polymerization (DPn 28) higher than the value of DPn 12-15 for inulins from other plant species. Furthermore, the methodology of freeze/thaw to enrich the chains allowed us to increase the DP, similarly to other methodologies used for the enrichment of inulin chains. The prebiotic assays confirm that inulin from S. rebaudiana has a high DP. The combined use of these molecules with low degree of polymerization fructans seems to be advantageous to prolong the prebiotic effect in the colon. Our results suggest that S. rebaudiana roots are a promising source of high degree polymerization inulins.
      Graphical abstract image

      PubDate: 2015-04-16T02:58:00Z
       
  • Structure of the O-polysaccharide of the lipopolysaccharide of Pseudomonas
           chlororaphis subsp. aureofaciens UCM B-306
    • Abstract: Publication date: Available online 11 April 2015
      Source:Carbohydrate Research
      Author(s): Evelina L. Zdorovenko , Liudmyla D. Varbanets , Alexander S. Shashkov , Elena A. Kiprianova , Yuriy A. Knirel
      Structure of the O-specific polysaccharide from Pseudomonas chlororaphis subsp. aureofaciens UCM B-306 was elucidated by sugar analysis along with 1D and 2D 1H and 13C NMR spectroscopy. The polysaccharide is built up of trisaccharide repeats containing D-rhamnose, 2,4-diacetamido-2,4,6-trideoxy-D-glucose (D-QuiNAc4NAc), and 2-acetamido-2-deoxy-D-galacturonic acid (D-GalNAcA), which is amidated in ∼40 % repeats. It was suggested that the O-polysaccharide has a blockwise structure, which can be presented as follows: -[→3)-α-d-Rhap-(1→4)-α-d-GalpNAcA-(1→3)-α-d-QuipNAc4NAc-(1-]n→ and -[→3)-α-d-Rhap-(1→4)-α-d-GalpNAcAN-(1→3)-α-d-QuipNAc4NAc-(1-]m→, where GalNAcAN indicates 2-acetamido-2-deoxy-d-galacturonamide, n:m = ∼3:2.
      Graphical abstract image

      PubDate: 2015-04-16T02:58:00Z
       
  • Synthesis of a 1,3 β-glucan hexasaccharide designed to target
           vaccines to the dendritic cell receptor, Dectin-1
    • Abstract: Publication date: 18 May 2015
      Source:Carbohydrate Research, Volume 408
      Author(s): Hassan R.H. Elsaidi , Eugenia Paszkiewicz , David R. Bundle
      Transformation of 3-O-benzyl-1,2:5,6-di-O-isopropylidene-α-d-glucofuranose into 2,4,6-tri-O-benzoyl-3-O-benzyl glucopyranosyl imidate proceeded efficiently via crystalline benzyl and per-benzoylated derivatives. This imidate glycosylated di-O-isopropylidene-α-d-glucofuranose in high yield and glycosylation of the disaccharide after removal of the 3′-O-benzyl ether afforded the β1,3 linked trisaccharide in excellent yield. Di- and trisaccharides imidates were readily prepared from the furanose terminated glycosylation products but both were unreactive in glycosylation reaction with the debenzylated di- and trisaccharide alcohols. The 3′-O-benzyl perbenzoylated disaccharide pyranose derivative could be selectively debenzoylated and converted to the corresponding perbenzoylated 4,6:4′,6′-di-O-benzylidene derivative. Lewis acid catalyzed glycosidation gave the selectively protected disaccharide ethylthioglycoside in good overall yield. Glycosidation of this thioglycoside donor with 5-methoxycarbonylpentanol gave the disaccharide tether glycoside and after catalytic removal of benzyl ether the resulting disaccharide alcohol was glycosylated by the thioglycoside in a 2+2 reaction to yield a tetrasaccharide. Repetition of selective deprotection of the terminal 3-O-benzyl ether followed by glycosylation by the disaccharide thioglycoside gave a protected hexasaccharide. Hydrogenolysis of this hexasaccharide followed by transesterification and second hydrogenolysis to remove a residual benzyl group gave the target hexasaccharide glycoside 1 as a Dectin-1 ligand functionalized to permit covalent attachment to glycoconjugate vaccines and thereby facilitate improved antigen processing by dendritic cells.
      Graphical abstract image

      PubDate: 2015-04-10T18:14:22Z
       
  • Common side reactions of the glycosyl donor in chemical glycosylation
    • Abstract: Publication date: 18 May 2015
      Source:Carbohydrate Research, Volume 408
      Author(s): Helle M. Christensen , Stefan Oscarson , Henrik H. Jensen
      Chemical glycosylation is central to carbohydrate chemistry and is generally recognised as a challenging reaction. This review describes the most reoccurring side reactions of glycosyl donors in glycosylation and how scientists have attempted to explain their observations and in some cases succeeded in solving a particular encountered problem. The topics covered are donor hydrolysis, elimination to form glycals, intermolecular aglycon transfer of thioglycosides and glycosyl imidate rearrangement.
      Graphical abstract image

      PubDate: 2015-04-10T18:14:22Z
       
  • Theoretical studies on the dissolution of chitosan in
           1-butyl-3-methylimidazolium acetate ionic liquid
    • Abstract: Publication date: 18 May 2015
      Source:Carbohydrate Research, Volume 408
      Author(s): Qingqing Tian , Shuangyue Liu , Xiaofu Sun , Haitao Sun , Zhimin Xue , Tiancheng Mu
      In this work, the dissolution mechanism of chitosan in imidazolium acetic-based ionic liquid (IL) 1-butyl-3-methylimidazolium acetate was investigated by density functional theory (DFT). Chitobiose is considered to symbolize chitosan during the DFT calculations. [Bmim]OAc is supposed to be the best suitable IL among the investigated ILs for the dissolution of chitosan since the complex formed between [Bmim]OAc and chitobiose has the lowest energy. The hydrogen bonds formed by IL and chitobiose were studied by discussing the geometric parameter variations and the vibration mode analyses. Four strong hydrogen-bond patterns C1–H1⋯O16, C2–H2⋯O16, O38–H39⋯O1 and O40–H41⋯O2 were found, which means the existence of strong interaction between chitosan and [Bmim]OAc. In addition, natural bond orbital (NBO) analysis was used to study the second order perturbation stabilization energies (E(2)) that denotes the intensity of the interactions between chitobiose with H2O and ILs. The E(2) of chitobiose with [Bmim]OAc is larger than that of chitobiose with other ILs and solvents studied, which proves that chitobiose can be dissolved in [Bmim]OAc but cannot in water and other solvents. Atom in molecules (AIM) theory shows that hydrogen bonds between chitobiose and [Bmim]OAc are stronger than that between chitobiose and other solvents. It means that the interactions between [Bmim]OAc and chitobiose interrupt the initial hydrogen bonds in the chitobiose due to the formation of new hydrogen bonds in the complexes. The calculation data provide the interaction mechanism of the dissolution of chitosan in [Bmim]OAc.
      Graphical abstract image

      PubDate: 2015-04-10T18:14:22Z
       
  • Editorial board
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407




      PubDate: 2015-04-06T18:09:40Z
       
  • Graphical contents list
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407




      PubDate: 2015-04-06T18:09:40Z
       
  • Novel family GH3 β-glucosidases or β-xylosidases of unknown
           function found in various animal groups, including birds and reptiles
    • Abstract: Publication date: 18 May 2015
      Source:Carbohydrate Research, Volume 408
      Author(s): Marek Gabriško , Štefan Janeček
      Proteins from the glycoside hydrolase family 3 (GH3) are important bacterial, fungal and plant enzymes involved in cell wall remodeling, energy metabolism and pathogen defense but no animal GH3 proteins have been reported so far. In presented work we use the in silico approach to describe putative GH3 proteins of animals. Based on tertiary structure modeling, domain organization and transcriptomics data analysis, presence of catalytic and substrate binding residues and evolutionary relationship inference, we assume that there is a monophyletic group of GH3 enzymes (probably β-xylosidases) found in various animal taxa with possible role in development.
      Graphical abstract image

      PubDate: 2015-04-01T18:01:12Z
       
  • Branched-chain sugar nucleosides: stereocontrolled synthesis and
           bioevaluation of novel 3′-C-trifluoromethyl and 3′-C-methyl
           pyranonucleosides
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Nikolaos Kollatos , Stella Manta , Athina Dimopoulou , Vanessa Parmenopoulou , Virginia V. Triantakonstanti , Tahsin Kellici , Thomas Mavromoustakos , Dominique Schols , Dimitri Komiotis
      A new series of 3′-C-trifluoromethyl- and 3′-C-methyl-β-d-allopyranonucleosides of 5-fluorouracil and their deoxy derivatives has been designed and synthesized. Treatment of ketosugar 1 with trifluoromethyltrimethylsilane under catalytic fluoride activation and methyl magnesium bromide, gave 1,2:5,6-di-O-isopropylidene-3-C-trifluoromethyl (2a) and 3-C-methyl (2b)-α-d-allofuranose, respectively, in a virtually quantitative yield and with complete stereoselectivity. Hydrolysis followed by acetylation led to the 1,2,4,6-tetra-O-acetyl-3-C-trifluoromethyl (3a) and 3-C-methyl (3b)-β-d-allopyranose. Compounds 3a,b were then condensed with silylated 5-fluorouracil and deacetylated to afford the target nucleosides 5a,b. Deoxygenation of the peracylated allopyranoses 3a,b followed by condensation with silylated 5-fluorouracil and subsequent deacetylation yielded the target 3′-deoxy-3′-C-trifluoromethyl and 3′-deoxy-3′-C-methyl-β-d-glucopyranonucleosides 14a,b. The newly synthesized compounds were evaluated for their potential antiviral and cytostatic activities. The 3′-deoxy-3′-C-methyl- ribonucleoside 11b showed significant cytotoxic activity (∼7 μM) almost equally active against a variety of tumor cell lines.
      Graphical abstract image

      PubDate: 2015-04-01T18:01:12Z
       
  • Novel substrate specificities of two lacto-N-biosidases towards
           β-linked galacto-N-biose-containing oligosaccharides of globo H,
           Gb5, and GA1
    • Abstract: Publication date: 18 May 2015
      Source:Carbohydrate Research, Volume 408
      Author(s): Aina Gotoh , Toshihiko Katoh , Yuta Sugiyama , Shin Kurihara , Yuji Honda , Haruko Sakurama , Taiho Kambe , Hisashi Ashida , Motomitsu Kitaoka , Kenji Yamamoto , Takane Katayama
      We describe the novel substrate specificities of two independently evolved lacto-N-biosidases (LnbX and LnbB) towards the sugar chains of globo- and ganglio-series glycosphingolipids. LnbX, a non-classified member of the glycoside hydrolase family, isolated from Bifidobacterium longum subsp. longum, was shown to liberate galacto-N-biose (GNB: Galβ1-3GalNAc) and 2′-fucosyl GNB (a type-4 trisaccharide) from Gb5 pentasaccharide and globo H hexasaccharide, respectively. LnbB, a member of the glycoside hydrolase family 20 isolated from Bifidobacterium bifidum, was shown to release GNB from Gb5 and GA1 oligosaccharides. This is the first report describing enzymatic release of β-linked GNB from natural substrates. These unique activities may play a role in modulating the microbial composition in the gut ecosystem, and may serve as new tools for elucidating the functions of sugar chains of glycosphingolipids.
      Graphical abstract image

      PubDate: 2015-04-01T18:01:12Z
       
  • Activation of enzymatic chitin degradation by a lytic polysaccharide
           monooxygenase
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Anne Grethe Hamre , Kristine B. Eide , Hanne H. Wold , Morten Sørlie
      For decades, the enzymatic conversion of recalcitrant polysaccharides such as cellulose and chitin was thought to solely rely on the synergistic action of hydrolytic enzymes, but recent work has shown that lytic polysaccharide monooxygenases (LPMOs) are important contributors to this process. Here, we have examined the initial rate enhancement an LPMO (CBP21) has on the hydrolytic enzymes (ChiA, ChiB, and ChiC) of the chitinolytic machinery of Serratia marcescens through determinations of apparent k cat (k cat app) values on a β-chitin substrate. k cat app values were determined to be 1.7±0.1 s−1 and 1.7±0.1 s−1 for the exo-active ChiA and ChiB, respectively and 1.2±0.1 s−1 for the endo-active ChiC. The addition of CBP21 boosted the k cat app values of ChiA and ChiB giving values of 11.1±1.5 s−1 and 13.9±1.4 s−1, while there was no effect on ChiC (0.9±0.1 s−1).
      Graphical abstract image

      PubDate: 2015-04-01T18:01:12Z
       
  • Chemotactic effect of mono- and disaccharides on the unicellular
           Tetrahymena pyriformis
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Áfonya Szemes , Eszter Lajkó , Orsolya Láng , László Kőhidai
      Chemotaxis is one of the most essential cell physiological responses, which was developed in parallel the molecular evolution of signal molecules. Previously good correlations were found between chemotactic moieties and physicochemical properties (SEA, solubility, pKa) of peptide type ligands in Tetrahymena model. However, references are rather weak in eukaryotic chemotaxis about significance of simple carbohydrates. In the present work our goal is (i) to investigate the chemotactic effect of 10 mono- and disaccharides in the eukaryotic Tetrahymena pyriformis; (ii) to describe effective ligands with physicochemical parameters; (iii) to test whether sugars are acting via induction of metabolic pathways. Our results are: (i) the tested sugars can trigger both significant attractant (d-glucose, d-mannose) and significant repellent (d-glucosamine, d-fructose, N-acetyl-d-galactosamine, d-arabinose) effects, while some of the sugars (maltose, lactose, sucrose, d-galactose) had no effect. (ii) Correlations were described between the chemotactic effectiveness of the ligands and their physicochemical characters (TPSA, XLogP), which are supposed to influence the internalization of the sugars. (iii) All ligands proved to have low selection potential, which refers to a ‘short-term’ receptor moiety or influencing specific metabolic pathways. (iv) Starvation elicited modified, strong chemoattractive responsiveness towards glucose; however, it was independent of concentration while 1 h insulin treatment resulted in an increased and concentration dependent chemotaxis induced by glucose.
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      PubDate: 2015-04-01T18:01:12Z
       
  • Cholesterol anchored arabinogalactan for asialoglycoprotein receptor
           targeting: synthesis, characterization, and proof of concept of
           hepatospecific delivery
    • Abstract: Publication date: 18 May 2015
      Source:Carbohydrate Research, Volume 408
      Author(s): Pankaj Omprakash Pathak , Mangal Shailesh Nagarsenker , Chandrashekhar Rishikant Barhate , Sameer Govind Padhye , Vivek Vijay Dhawan , Dibyendu Bhattacharyya , C.L. Viswanathan , Frank Steiniger , Alfred Fahr
      Asialoglycoprotein receptors (ASGPR) are hepatocyte bound receptors, which exhibit receptor mediated endocytosis (RME) for galactose specific moieties. Arabinogalactan (AG), a liver specific high galactose containing branched polysaccharide was hydrophobized using cholesterol (CHOL) as a lipid anchor via a two step reaction process to yield the novel polysaccharide lipid conjugated ligand (CHOL-AL-AG). CHOL-AL-AG was characterized by Fourier transform infra red (FTIR) spectroscopy, 1H and 13C nuclear magnetic spectroscopy (NMR), size exclusion chromatography (SEC) and differential scanning calorimetry (DSC). Conventional liposomes (CL) and surface modified liposomes (SML) containing CHOL-AL-AG were prepared using reverse phase evaporation technique. Effect of CHOL-AL-AG concentration on particle size and zeta potential of SML was evaluated. Surface morphology of CL and SML was studied using cryo-transmission electron microscopy (cryo-TEM). In vitro binding affinity of SML and CL was evaluated using Ricinus communis agglutinin (RCA) assay. Cellular uptake of SML and CL was determined on ASGPR expressing HepG2 cell lines by confocal laser scanning microscopy technique (CLSM). FTIR spectra revealed bands at 1736 cm−1 and 1664 cm−1 corresponding to ester and carbamate functional groups, respectively. Signals at δ 0.5–2.5 corresponding to the cholestene ring and δ 3–5.5 corresponding to the carbohydrate backbone were observed in 1H NMR spectrum of the product. CHOL-AL-AG possessed a mean average molecular weight of 27 KDa as determined by size exclusion chromatography. An endothermic peak at 207 °C was observed in the DSC thermogram of CHOL-AL-AG, which was not observed in thermograms of reactants and intermediate product. Synthesized CHOL-AL-AG was successfully incorporated in liposomes to yield SML. Both CL and SML possessed a mean particle size of∼200 nm with polydispersity index of∼0.25. The zeta potential of CLs was observed to be −17 mV whereas zeta potential of SMLs varied from −18 to −22 mV. RCA assay revealed enhanced binding of SML compared to CL confirming presence of galactose on surface of SML. CLSM studies demonstrated enhanced cellular uptake of SMLs compared to CL by HepG2 cells post 3 h administration indicating enhanced uptake by the ASGPR. Thus surface modified liposomes specific to target heptocytes demonstrate a promising approach for targeted drug delivery in liver cancer therapeutics.
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      PubDate: 2015-04-01T18:01:12Z
       
  • Structure elucidation of the capsular polysaccharide of Acinetobacter
           baumannii AB5075 having the KL25 capsule biosynthesis locus
    • Abstract: Publication date: 18 May 2015
      Source:Carbohydrate Research, Volume 408
      Author(s): Sof'ya N. Senchenkova , Alexander S. Shashkov , Anastasiya V. Popova , Mikhail M. Shneider , Nikolay P. Arbatsky , Konstantin A. Miroshnikov , Nikolay V. Volozhantsev , Yuriy A. Knirel
      Capsular polysaccharide was isolated by the phenol–water extraction of Acinetobacter baumannii AB5075 and studied by 1D and 2D 1H and 13C NMR spectroscopy. The following structure of the linear trisaccharide repeating unit was established: →3)-β-d-ManpNAcA-(1→4)-β-d-ManpNAcA-(1→3)-α-d-QuipNAc4NR-(1→ where R indicates (S)-3-hydroxybutanoyl or acetyl in the ratio∼2.5:1. The genes in the polysaccharide biosynthesis locus designated KL25 are appropriate to the established CPS structure.
      Graphical abstract image

      PubDate: 2015-04-01T18:01:12Z
       
  • Molecular simulations of hevein/(GlcNAc)3 complex with weakened OH/O and
           CH/π hydrogen bonds: implications for their role in complex
           stabilization
    • Abstract: Publication date: 18 May 2015
      Source:Carbohydrate Research, Volume 408
      Author(s): Václav Mareška , Igor Tvaroška , Blanka Králová , Vojtěch Spiwok
      Carbohydrate–protein complexes are often characterized by interactions via aromatic amino acid residues. Several mechanisms have been proposed to explain these stacking-like interactions between pyranose sugars and aromatic moieties. The physical basis of these interactions is being explained as either dispersion CH/π or hydrophobic. In order to elucidate the nature of these interactions, we performed a series of molecular dynamics simulation of hevein domain (HEV32) in complex with (β-d-GlcNAc)3. Selected OH/O and CH/π hydrogen bonds involved in carbohydrate recognition were artificially weakened in 100ns molecular dynamics simulations. Separate weakening of either OH/O or CH/π hydrogen bonds was not sufficient to destabilize the complex. This indicates that other effects, not solely CH/π dispersion interactions, contribute significantly to the stability of the complex. Significant destabilization of complexes was reached only by simultaneous weakening of OH/O and CH/π hydrogen bonds. This also shows that classical hydrogen bonds and CH/π interactions are working in concert to stabilize this carbohydrate–protein test case.
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      PubDate: 2015-04-01T18:01:12Z
       
  • Mannoproteins from yeast and hyphal form of Candida albicans considerably
           differ in mannan and protein content
    • Abstract: Publication date: 18 May 2015
      Source:Carbohydrate Research, Volume 408
      Author(s): Eva Machová , Lucia Fiačanová , Alžbeta Čížová , Jana Korcová
      Significant differences in carbohydrate composition of mannoproteins obtained from yeast and hyphal cell walls of Candida albicans (serotypes A and B) were found. Yeast mannoproteins from both serotypes consisted up to 46% of mannan while the same parts from hyphal cells contained only about 14% of mannan. Another difference was in protein content, 47–53% for yeasts, 3–4.5% for hyphae, respectively. Moreover, HPLC profiles of yeast mannoproteins were more complex compared to those of hyphal form. Subsequently, mannans were prepared from yeast and hyphal mannoproteins using cetavlon fractionation. Mannans from both yeast serotypes contained higher amounts of mannose (91.4% serotype A; 92.8% serotype B) than mannans from hyphae (66.4% serotype A; 76.3% serotype B). Unlike mannans from serotype B, mannans from serotype A contained β-(1→2)-linked mannopyranosyl units in acid-stable moiety. Further, hyphal mannans were less branched than yeast mannans. The shift from yeast to hyphal form probably led to simplification of mannan structure.
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      PubDate: 2015-04-01T18:01:12Z
       
  • Synthesis, conformational study, glycosidase inhibitory activity and
           molecular docking studies of dihydroxylated 4- and 5-amino-iminosugars
    • Abstract: Publication date: 18 May 2015
      Source:Carbohydrate Research, Volume 408
      Author(s): Vijay M. Kasture , Navnath B. Kalamkar , Roopa J. Nair , Rakesh S. Joshi , Sushma G. Sabharwal , Dilip D. Dhavale
      An efficient methodology for the synthesis of new amino iminosugars 6a, 7a and 8, starting from d-glucose, is reported. The conformational study using 1H NMR data showed that the amino iminosugar 6a exists in the 2 C 5 while; the 7a and 8 exist in the 5 C 2 conformation. The inhibition activities with different glycosidases showed that 6a and 7a are poor glycosidase inhibitors. However, amino iminosugar 8 showed selective inhibition against the β-galactosidase (IC50=43 μM, Ki=153 μM). These results are substantiated by the molecular docking studies.
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      PubDate: 2015-04-01T18:01:12Z
       
  • Structure of a new pseudaminic acid-containing capsular polysaccharide of
           Acinetobacter baumannii LUH5550 having the KL42 capsule biosynthesis locus
           
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Sof'ya N. Senchenkova , Anastasiya V. Popova , Alexander S. Shashkov , Mikhail M. Shneider , Zhu Mei , Nikolay P. Arbatsky , Bin Liu , Konstantin A. Miroshnikov , Nikolay V. Volozhantsev , Yuriy A. Knirel
      The capsular polysaccharide from Acinetobacter baumannii LUH5550 was studied by 1D and 2D 1H and 13C NMR spectroscopy. The following structure of the branched trisaccharide repeating unit was established: where Pse5Ac7RHb indicates 5-acetamido-3,5,7,9-tetradeoxy-7-[(R)-3-hydroxybutanoylamino]-l-glycero-l-manno-non-2-ulosonic acid. The genes in the capsule biosynthesis locus designated KL42 are consistent with the structure established.
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      PubDate: 2015-03-16T13:03:57Z
       
  • C-glycosphingolipid precursors via iodocyclization of homoallyic
           trichloroacetimidates
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Ahmad S. Altiti , David R. Mootoo
      The iodocyclization of homoallylic trichloroacetimidates derived from α-C-allyl galactoside were investigated. In line with the stereochemical trend observed for less substituted non-glycosylated frameworks, E and Z substrates delivered stereoselectively the 1,3-anti and 1,3-syn amino alcohol motifs, respectively. These products are advanced precursors to C-glycosides of the potent immunostimulatory glycolipid KRN7000.
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      PubDate: 2015-03-16T13:03:57Z
       
  • Mechanochemical click reaction as a tool for making carbohydrate-based
           triazole-linked self-assembling materials (CTSAMs)
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Mohit Tyagi , Nikhil Taxak , Prasad V. Bharatam , Hemraj Nandanwar , K.P. Ravindranathan Kartha
      Various glycosides in which glycosylated triazole residues are anchored on to a central phenyl ring have been prepared under green reaction conditions by a solvent-free mechanochemical method. Some of the glycosides exhibited the ability to form gels when in contact with long chain hydrocarbons, e.g. hexane, heptane and octane, and this property was phase-selective. Thus, from a mixture of hexane–water, the compounds preferably absorbed the alkane to form a gel. The gelation ability was found to increase with an increasing number of substituents on the phenyl ring but only up to tetra-substitution. The hexa-substituted phenyl derivative did not swell in the hydrocarbon solvents investigated. The spontaneous self-assembling properties of these compounds in hexane have been investigated by transmission electron microscopy (TEM). Molecular modelling was used to optimize the structural geometry of these carbohydrate-based triazole-linked self-assembling materials (CTSAMs) and to rationalize their behaviour.
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      PubDate: 2015-03-16T13:03:57Z
       
  • Classification of a Proteus penneri clinical isolate with a unique
           O-antigen structure to a new Proteus serogroup, O80
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Małgorzata Siwińska , Evgeniya A. Levina , Olga G. Ovchinnikova , Dominika Drzewiecka , Alexander S. Shashkov , Antoni Różalski , Yuriy A. Knirel
      Proteus penneri is an opportunistic pathogen, which may cause severe diseases, most frequently urinary tract infections in immunocompromised patients. P. penneri Br 114 exhibiting a good swarming growth ability as an S-form strain was isolated from a wound of a patient in Łódź, Poland. Serological studies using ELISA and Western blotting and chemical analyses along with 1H and 13C NMR spectroscopy showed that the O-antigen (O-polysaccharide) of this strain is unique among the known Proteus serotypes O1–O79. It possesses a linear pentasaccharide repeating unit containing a partially O-acetylated amide of d-glucuronic acid (GlcA) with l-serine having the following structure: These data are a basis for creating a new Proteus serogroup, O80, so far represented by the single Br 114 isolate. The O80 is the 21st O-serogroup containing P. penneri strains and the fourth serogroup based on Proteus spp. clinical isolates from Łódź, Poland.
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      PubDate: 2015-03-13T06:59:38Z
       
  • A recyclable heavy fluorous tag carrying an allyl alcohol pendant group:
           design and evaluation toward applications in synthetic carbohydrate
           chemistry
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Kazuo Fukuda , Mami Tojino , Kohtaro Goto , Hirofumi Dohi , Yoshihiro Nishida , Mamoru Mizuno
      Toward applications in synthetic carbohydrate chemistry, we converted our previous acid-resistant heavy fluorous tag [(Rf)3C–CH2–OH, 1] to allyl alcohol derivatives [(Rf)3C–CH2–O–(CH2) n –CHCH–CH2–OH, 3 (n=1) or 4 (n=3)] by means of olefin cross metathesis. They were then subjected to β-glycosylation reactions by using a series of glycosyl donors, including glycosyl bromide and trichloroacetimidates. The terminal OH group in 3 and 4 was found to be β-glycosylated in moderate yield when 2,3,4,6-tetra-O-benzoyl-d-galactosyl trichloroacetimidate was used as the glycosyl donor. Upon a detachment reaction using Pd(PPh3)4, the initial heavy fluorous tag 1 was recovered in high yield (>90%) together with 1-hydroxy sugar, indicating that not only the allyl ether linkage in the glycosides but also the internal di-alkyl ether linkage in 4 be cleaved by the action of the Pd-catalyst enabling long-range olefin transmigration. Potential utility was demonstrated by using the tetra-O-benzoyl-β-d-galactosylated derivative of 3 in a series of deprotection, protection and glycosylation reactions, which were conductible in high yields without using chromatographic purification process. These findings prompt us to propose a general scheme in which the acid-resistant heavy fluorous compound 1 is applied as a recyclable tag in synthetic carbohydrate chemistry.
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      PubDate: 2015-03-13T06:59:38Z
       
  • Ferrier rearrangement promoted by an electrochemically generated zirconium
           catalyst
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Dragana Stevanović , Anka Pejović , Ivan Damljanović , Aleksandra Minić , Goran A. Bogdanović , Mirjana Vukićević , Niko S. Radulović , Rastko D. Vukićević
      In situ generated zirconium catalyst from a sacrificial zirconium anode was successfully applied to promote Ferrier rearrangement of 3,4,5-tri-O-acetyl-d-glucal and 6-deoxy-3,4-di-O-acetyl-l-glucal (3,4-di-O-acetyl-l-rhamnal) in the presence of three thiols and eleven thiophenols as nucleophiles. A simple constant current electrolysis (20 mA, 0.4 F mol−1) of an acetonitrile solution of lithium perchlorate (0.1 M) containing the corresponding glycal and S-nucleophiles, using a zirconium anode and a platinum cathode resulted in the successful synthesis of the corresponding 2,3-unsaturated peracetylated thioglycosides (with an average anomer ratio α/β=4.129 in the case of peracetylated d-glucal and 8.740 in the case of l-rhamnal). The same procedure proved to be appropriate in synthesizing dihydropyran derivatives (‘C-glycosides’) using allyltrimethylsilane as the nucleophile (only ‘α-anomers’ were obtained). All new compounds were fully characterized by spectral data, whereas single-crystal X-ray analysis was performed for two thioglycosides.
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      PubDate: 2015-03-09T13:00:35Z
       
  • Synthesis of novel Schiff base ligands from gluco- and galactochloraloses
           for the Cu(II) catalyzed asymmetric Henry reaction
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Sevda Alkan , Fatma Ç. Telli , Yeşim Salman , Stephen T. Astley
      A series of chiral Schiff base ligands has been prepared using aminochloralose derivatives of glucose and galactose. These ligands were used as catalysts in the asymmetric Henry reaction in the presence of Cu(II) ions giving yields of up to 95%. An interesting solvent dependency on enantiomeric control was observed with the best enantiomeric excesses (up to 91%) being obtained in the presence of water.
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      PubDate: 2015-03-09T13:00:35Z
       
  • Spectroscopic and structural studies on lactose species in aqueous
           solution combining the HATR and Raman spectra with SCRF calculations
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): María Jimena Márquez , Alicia Beatriz Brizuela , Lilian Davies , Silvia Antonia Brandán
      In this work, the α and β isomers, the α-lactose monohydrate and dihydrate and the dimeric species of lactose were studied from the spectroscopic point of view in gas and aqueous solution phases combining the infrared, Horizontal Attenuated Total Reflectance (HATR) and Raman spectra with the density functional theory (DFT) calculations. Aqueous saturated solutions of α-lactose monohydrate and solutions at different molar concentrations of α-lactose monohydrate in water were completely characterized by infrared, HATR and Raman spectroscopies. For all the species in solution, the solvent effects were studied using the solvation polarizable continuum (PCM) and solvation (SM) models and, then, their corresponding solvation energies were predicted. The vibrational spectra of those species in aqueous solution were completely assigned by employing the Scaled Quantum Mechanics Force Field (SQMFF) methodology and the self-consistent reaction field (SCRF) calculations. The stabilities of all those species were studied by using the natural bond orbital (NBO), and atoms in molecules (AIM) calculations.
      Graphical abstract image

      PubDate: 2015-03-09T13:00:35Z
       
  • Fragment profiling of low molecular weight heparins using reversed phase
           ion pair liquid chromatography-electrospray mass spectrometry
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Xiaohui Xu , Daoyuan Li , Lequan Chi , Xuzhao Du , Xue Bai , Lianli Chi
      Low molecular weight heparins (LMWHs) are linear and highly charged carbohydrate polymers prepared by chemical or enzymatic depolymerization of heparin. Compared to unfractionated heparin (UFH), LMWHs are prevalently used as clinical anticoagulant drugs due to their lower side effects and better bioavailability. The work presented herein provides a rapid and powerful fragment mapping method for structural characterization of LMWHs. The chain fragments of two types of LMWHs, enoxaparin and nadroparin, were generated by controlled enzymatic digestion with each of heparinase I (Hep I, Enzyme Commission (EC) # 4.2.2.7), heparinase II (Hep II, no EC # assigned) and heparinase III (Hep III, EC # 4.2.2.8). Reversed phase ion pair high performance liquid chromatography (RPIP-HPLC) coupled with electrospray ion trap time-of-flight mass spectrometry (ESI-IT-TOF-MS) was used to profile the oligosaccharide chains ranging from disaccharides to decasaccharides. A database containing all theoretical structural compositions was established to assist the mass spectra interpretation. The six digests derived by three enzymes from two types of LMWHs exhibited distinguishable fingerprinting patterns. And a total of 94 enoxaparin fragments and 109 nadroparin fragments were detected and identified. Besides the common LMWH oligosaccharides, many components containing characteristic LMWH structures such as saturated l-idopyranosuronic acid, 2,5-anhydro-d-mannitol, 1,6-anhydro-d-aminopyranose, as well as odd number oligosaccharides were also revealed. Quantitative comparison of major components derived from innovator and generic nadroparin products was presented. This approach to profile LMWHs' fragments offers a highly reproducible, high resolution and information-rich tool for evaluating the quality of this category of anticoagulant drugs or comparing structural similarities among samples from various sources.
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      PubDate: 2015-03-09T13:00:35Z
       
  • Isolation and characterization of feruloylated arabinoxylan
           oligosaccharides from the perennial cereal grain intermediate wheat grass
           (Thinopyrum intermedium)
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Rachel R. Schendel , Andreas Becker , Catrin E. Tyl , Mirko Bunzel
      In comparison to the annual grain crops dominating current agricultural production, perennial grain species require fewer chemical and energy inputs and improve soil health and erosion control. The possibility for producing sustainable grain harvests from marginal land areas is motivating research initiatives to integrate perennial grains into commercial cropping and food processing systems. In this study, the feruloylated arabinoxylans from intermediate wheat grass (Thinopyrum intermedium, IWG), a promising perennial grain candidate in agronomic screening studies, were investigated. Insoluble fiber isolated from IWG whole grain flour was subjected to either mildly acidic (50 mM TFA, 100 °C, 2 h) or enzymatic (Driselase) hydrolysis. The liberated feruloylated arabinoxylan oligosaccharides were concentrated with Amberlite XAD-2, separated with gel chromatography (Sephadex LH-20, water), and purified with reversed-phase HPLC (C18, water-MeOH gradient). Thirteen feruloylated oligosaccharides were isolated (including eight structures described for the first time) and identified by LC-ESI-MS and NMR. Linkage-type analysis via methylation analysis, as well as the monosaccharide and phenolic acid profiles of the IWG insoluble fiber were also determined. IWG feruloylated arabinoxylans have a relatively simple structure with only short feruloylated side chains, a lower backbone substitution rate than annual rye and wheat varieties, and a moderate phenolic acid content.
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      PubDate: 2015-03-09T13:00:35Z
       
  • Hydrolysis of wheat flour arabinoxylan, acid-debranched wheat flour
           arabinoxylan and arabino-xylo-oligosaccharides by β-xylanase,
           α-l-arabinofuranosidase and β-xylosidase
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Barry V. McCleary , Vincent A. McKie , Anna Draga , Edward Rooney , David Mangan , Jennifer Larkin
      A range of α-l-arabinofuranosyl-(1-4)-β-d-xylo-oligosaccharides (AXOS) were produced by hydrolysis of wheat flour arabinoxylan (WAX) and acid debranched arabinoxylan (ADWAX), in the presence and absence of an AXH-d3 α-l-arabinofuranosidase, by several GH10 and GH11 β-xylanases. The structures of the oligosaccharides were characterised by GC-MS and NMR and by hydrolysis by a range of α-l-arabinofuranosidases and β-xylosidase. The AXOS were purified and used to characterise the action patterns of the specific α-l-arabinofuranosidases. These enzymes, in combination with either Cellvibrio mixtus or Neocallimastix patriciarum β-xylanase, were used to produce elevated levels of specific AXOS on hydrolysis of WAX, such as 32-α-l-Araf-(1-4)-β-d-xylobiose (A3X), 23-α-l-Araf-(1-4)-β-d-xylotriose (A2XX), 33-α-l-Araf-(1-4)-β-d-xylotriose (A3XX), 22-α-l-Araf-(1-4)-β-d-xylotriose (XA2X), 32-α-l-Araf (1-4)-β-d-xylotriose (XA3X), 23-α-l-Araf-(1-4)-β-d-xylotetraose (XA2XX), 33-α-l-Araf-(1-4)-β-d-xylotetraose (XA3XX), 23,33-di-α-l-Araf-(1-4)-β-d-xylotriose (A2+3XX), 23,33-di-α-l-Araf-(1-4)-β-d-xylotetraose (XA2+3XX), 24,34-di-α-l-Araf-(1-4)-β-d-xylopentaose (XA2+3XXX) and 33,34-di-α-l-Araf-(1-4)-β-d-xylopentaose (XA3A3XX), many of which have not previously been produced in sufficient quantities to allow their use as substrates in further enzymic studies. For A2,3XX, yields of approximately 16% of the starting material (wheat arabinoxylan) have been achieved. Mixtures of the α-l-arabinofuranosidases, with specific action on AXOS, have been combined with β-xylosidase and β-xylanase to obtain an optimal mixture for hydrolysis of arabinoxylan to l-arabinose and d-xylose.
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      PubDate: 2015-03-09T13:00:35Z
       
  • Isolation and characterization of unhydrolyzed oligosaccharides from
           switchgrass (Panicum virgatum, L.) xylan after exhaustive enzymatic
           treatment with commercial enzyme preparations
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Michael J. Bowman , Bruce S. Dien , Karl E. Vermillion , Jeffrey A. Mertens
      Switchgrass (Panicum virgatum, L.) is a potential renewable source of carbohydrates for use in microbial conversion to biofuels. Xylan comprises approximately 30% of the switchgrass cell wall. To understand the limitations of commercial enzyme mixtures, alkali-extracted, isolated switchgrass xylan was hydrolyzed by the action of two commercial enzyme cocktails, in the presence and absence of an additional α-arabinofuranosidase enzyme. The two most abundant enzymatic digestion products from each commercial enzyme treatment were separated and characterized by LC-MS n , linkage analysis, and NMR. The most abundant oligosaccharide from each commercial cocktail was susceptible to hydrolysis when supplemented with a GH62 α-arabinofuranosidase enzyme; further characterization confirmed the presence of (1→3)-α-arabinose linkages. These results demonstrate the lack of the required selectivity for arabinose-containing substrates in the commercial enzyme preparations tested. One product from each condition remained intact and was found to contain (1→2)-β-xylose-(1→3)-α-arabinose side chains; this linkage acts as a source of oligosaccharide recalcitrance.
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      PubDate: 2015-03-09T13:00:35Z
       
  • Characteristics of mannosylerythritol lipids and their environmental
           potential
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Mingda Yu , Zhifeng Liu , Guangming Zeng , Hua Zhong , Yang Liu , Yongbing Jiang , Min Li , Xiaoxiao He , Yan He
      Mannosylerythritol lipids (MELs) are promising biosurfactants containing two glycosyl derivatives and various fatty acids, which are mainly secreted by Pseudozyma as well as Ustilago. In this review, the latest research is demonstrated on production conditions, structural diversity, self-assembling properties and versatile biochemical functions of MELs. The genetic study and synthetic pathways, which mainly influence the type and yield of MELs production. Due to the excellent surface activity, biocompatibility and restorative function, MELs can be used in enviornmental industry, which has not been widely noted. In this paper, the current status of research on enviornmental potential of MELs has been discussed including petroleum degradation, bioconversion of chemical wastes and enhanced bioremediation of amphiphilic wastes.
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      PubDate: 2015-03-09T13:00:35Z
       
  • Kinetic characterization of Aspergillus niger chitinase CfcI using a
           HPAEC-PAD method for native chitin oligosaccharides
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Jolanda M. van Munster , Peter Sanders , Geralt A. ten Kate , Lubbert Dijkhuizen , Marc J.E.C. van der Maarel
      The abundant polymer chitin can be degraded by chitinases (EC 3.2.1.14) and β-N-acetyl-hexosaminidases (EC 3.2.1.52) to oligosaccharides and N-acetyl-glucosamine (GlcNAc) monomers. Kinetic characterization of these enzymes requires product quantification by an assay method with a low detection limit, preferably compatible with the use of native, non-labeled substrates. Here we report a quantitative HPAEC-PAD method that allows fast separation of chitin oligosaccharides (COS) ranging from (GlcNac)1–6 at detection limits of 1–3 pmol and a linear range of 5–250 pmol. Quantification under intra- and interday precision conditions was performed with 2.1–5.4% relative standard deviation (RSD) and 1.2–10.3% RSD, respectively. This method was successfully used for the determination of the kinetic parameters of the Aspergillus niger chitinase CfcI with native COS. CfcI was recently shown to release GlcNAc from the reducing end of COS, a new activity for fungal chitinases. A Carbohydrate Binding Module of family 18 (CBM18) is inserted in the CfcI catalytic domain. Site directed mutagenesis was used to assess the functionality of this CfcI-CBM18: four of its key amino acids were replaced by glycine residues, yielding CfcISYNF. Comparison of the kinetic parameters of CfcI and CfcISYNF confirmed that this CBM18 is functionally involved in catalysis.
      Graphical abstract image

      PubDate: 2015-03-09T13:00:35Z
       
  • Structure of a zwitterionic O-polysaccharide from Photorhabdus temperata
           subsp. cinerea 3240
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Anna N. Kondakova , Nadezhda A. Kirsheva , Nikolay P. Arbatsky , Rima Z. Shaikhutdinova , Alexander S. Shashkov , Sergey A. Ivanov , Andrey P. Anisimov , Yuriy A. Knirel
      A phosphorylated O-polysaccharide was isolated from the lipopolysaccharide of an entomopathogenic bacterium Photorhabdus temperata subsp. cinerea 3240 and studied by sugar analysis, dephosphorylation, and 1H and 13C NMR spectroscopy. The following structure of the linear trisaccharide repeating unit of the O-polysaccharide was established: →3)-β-d-GalpNAc4PEtN-(1→4)-β-d-GlcpA-(1→3)-β-d-FucpNAc4N-(1→ where GlcA indicates glucuronic acid, FucNAc4N 2-acetamido-4-amino-2,4,6-trideoxygalactose, and PEtN 2-aminoethyl phosphate.
      Graphical abstract image

      PubDate: 2015-03-09T13:00:35Z
       
  • Mass spectrometry-based method to investigate the natural selectivity of
           sucrose as the sugar transport form for plants
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Hang Yuan , Yile Wu , Wu Liu , Yan Liu , Xiang Gao , Jinming Lin , Yufen Zhao
      Sucrose is the carbon skeletons and energy vector for plants, which is important for plants growth. Among thousands of disaccharides in Nature, why chose sucrose for plants? In this paper, we analyzed the intrinsic structural characteristics of four sucrose isomers with different glycosidic linkage by mass spectrometry (MS) technique. Our results show that sucrose has the most labile glycosidic bond compared with other three isomers, which is helpful for releasing glucose and fructose unit. Besides, sucrose has the most stable integral structure, which is hard to dehydrate and degrade into fragments through losing one or three even four-carbon units, just as its three isomers. In other words, sucrose is more easily holds an integral structure during the transport process, whenever it is necessary, and sucrose can be cleaved into glucose and fructose easily. Besides, we also investigate the internal relationship of sucrose with K+ by tandem mass spectrometry and viscosity measurement. The related results have shown that the K+ can stabilize sucrose to a greater extent than the Na+. Furthermore, under the same conditions, K+ ions reduce the viscosity of sucrose–water system much more than Na+. These results suggest that K+ is a better co-transporter for sucrose. Of course, the transport of sucrose in plants is a very complicated process, which is involved in many proteins. This paper directly accounts for the basic structure feature of sucrose, and the results discovered could provide the novel insight for the answer why Nature chose sucrose for plants.
      Graphical abstract image

      PubDate: 2015-03-09T13:00:35Z
       
  • Nuclear magnetic resonance studies of the interactions between the organic
           germanium compound Ge-132 and saccharides
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Yasuhiro Shimada , Katsuyuki Sato , Yoshihiko Tokuji , Takashi Nakamura
      Poly-trans-[(2-carboxyethyl)germasesquioxane], Ge-132, is a water-soluble organic germanium compound with many reported physiological functions. The hydrolysate of Ge-132, 3-(trihydroxygermyl)propanoic acid, can interact with diol compounds; therefore, it can possibly interact with diol-containing sugar compounds, which have important physiological functions in sugar chains, glycoproteins, and glucolipids. In this study, we examined the interaction between sodium 3-(trihydroxygermyl)propanoate and monosaccharides using nuclear magnetic resonance. When 1,4-anhydroerythritol was mixed with sodium 3-(trihydroxygermyl)propanoate, a pattern of signals different from that obtained for each solute alone was observed. Some signals were broader, and novel signals with different chemical shifts appeared to originate from complex formation. Spectral observations for sodium 3-(trihydroxygermyl)propanoate and the sugar isomers of glucose and fructose indicated that sodium 3-(trihydroxygermyl)propanoate has a higher affinity for fructose (a ketose) than glucose (an aldose). Moreover, the β-furanosyl conformation of fructose was the structure that interacted most with sodium 3-(trihydroxygermyl)propanoate. These results demonstrate the ability of aqueous Ge-132 to form complexes with the cis-diol structures of saccharides. Thus, interactions among 3-(trihydroxygermyl)propanoic acid and the important biological sugar compounds might be implicated in the physiological function of Ge-132.
      Graphical abstract image

      PubDate: 2015-03-09T13:00:35Z
       
  • Room-temperature ionic liquids enhanced green synthesis of β-glycosyl
           1-ester
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Yanli Cui , Minghan Xu , Weirong Yao , Jianwei Mao
      We herein report an efficient synthesis of β-glycosyl 1-ester in room-temperature ionic liquids (RTILs) promoted via silver salt and quaternary ammonium salt (PTC) with good or excellent yields. All products were isolated exclusively as the β-anomers. Four different RTILs, eight metal salts and four quaternary ammonium salts were screened in the glycosylation reaction. The synergistic effect of C6mim·OTf, Ag2O and tetrabutylammonium iodine gave the best results. Their promotion to the system was integral. Thorough study provided insight into the catalytic activity of ionic liquid structure, metal salts and quaternary ammonium salt to these reactions. It is worth mentioning that the yield of aliphatic compound 2,3,4,6-tetra-O-acetyl-β-d-galactopyranosyl butyrate (3l) was highly improved when using C6mim·OTf as solvent compared with the normal volatile solvents under the same catalysts. This green approach has been proved to be practical and compatible with a wide range from aliphatic to aromatic substrates.
      Graphical abstract image

      PubDate: 2015-03-09T13:00:35Z
       
  • Structural studies of O-polysaccharide isolated from Cronobacter sakazakii
           Sequence Type 12 from a case of neonatal necrotizing enterocolitis
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Kinga Marszewska , Małgorzata Czerwicka , Stephen J. Forsythe , Karolina Ossowska , Halina Dziadziuszko , Zbigniew Kaczyński
      The O-polysaccharide (OPS) of Cronobacter sakazakii NTU 696 (Sequence Type 12) from a case of neonatal necrotizing enterocolitis was isolated from the polysaccharide fraction obtained after lipopolysaccharide (LPS) hydrolysis. Purified OPS was analyzed by NMR spectroscopy (1H, COSY, TOCSY, NOESY, HSQC, HSQC-TOCSY and HMBC experiments) and chemical methods. Obtained monosaccharide derivatives analyzed by gas chromatography and gas chromatography-mass spectrometry allowed the identification of six sugar components. Performed experiments enabled to establish a structure of the OPS repeating unit of C. sakazakii NTU 696, as:
      Graphical abstract image

      PubDate: 2015-03-09T13:00:35Z
       
  • Structure and genetics of the O-antigen of Enterobacter cloacae G3054
           containing di-N-acetylpseudaminic acid
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Andrei V. Perepelov , Min Wang , Andrei V. Filatov , Xi Guo , Alexander S. Shashkov , Lei Wang , Yuriy A. Knirel
      Mild acid degradation of the lipopolysaccharide of Enterobacter cloacae G3054 resulted in the cleavage of the O-polysaccharide at the linkage of residues of 5,7-diacetamido-3,5,7,9-tetradeoxy-l-glycero-l-manno-non-2-ulosonic acid (di-N-acetylpseudaminic acid, Pse5Ac7Ac) in the main chain. The resultant oligosaccharide and an alkali-treated lipopolysaccharide were studied by sugar analysis along with 1H and 13C NMR spectroscopy, and the following structure of the branched pentasaccharide O-unit of the O-polysaccharide was established: The O-antigen gene cluster of E. cloacae G3054 between conserved genes galF and gnd was sequenced. Most genes necessary for the O-antigen synthesis were found in the cluster and their functions were tentatively assigned by comparison with sequences in the available databases.
      Graphical abstract image

      PubDate: 2015-03-09T13:00:35Z
       
  • Synthesis and biotinylation of oligosaccharide fragments of mannosylated
           and 5-deoxy-5-methylthio-xylofuranosylated lipoarabinomannan from
           Mycobacterium tuberculosis
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Pintu Kumar Mandal , Pratik Rajesh Chheda
      The attachment of biotin to a molecule provides a powerful tool in biology. Here, we report an efficient synthesis and biotinylation of mannosylated and 5-deoxy-5-methylthio-xylofuranosylated Lipoarabinomannan from Mycobacterium tuberculosis. Preparation of the oligosaccharides involved the sequential addition of thioglycoside donors with arabinofuranosyl-containing acceptors. Methylthio group was introduced near the end of the synthesis.
      Graphical abstract image

      PubDate: 2015-03-09T13:00:35Z
       
  • Editorial board
    • Abstract: Publication date: 10 April 2015
      Source:Carbohydrate Research, Volume 406




      PubDate: 2015-03-09T13:00:35Z
       
  • Graphical contents list
    • Abstract: Publication date: 10 April 2015
      Source:Carbohydrate Research, Volume 406




      PubDate: 2015-03-09T13:00:35Z
       
  • Synthesis, emulsification and self-assembly properties of sugar-containing
           semifluorinated amphiphiles
    • Abstract: Publication date: 10 April 2015
      Source:Carbohydrate Research, Volume 406
      Author(s): Andrew V. Razgulin , Sandro Mecozzi
      Surfactants with two and three monosaccharide-based heads and a perfluoroalkyl tail have been synthesized. Perfluoroalkyl C3-symmetric triol and C2-symmetric diol were conveniently prepared via Cu-catalyzed azide–alkyne cycloaddition between a fluorous alkyne and tertiary and secondary azides, respectively. Glycosylation of the perfluoroalkyl diol and triol led to orthoester-type structures, which were evaluated for their capacity to stabilize aqueous emulsions of highly fluorinated anesthetics. The self-assembly properties of the tri-sugar amphiphile were examined by transmission electron microscopy.
      Graphical abstract image

      PubDate: 2015-03-09T13:00:35Z
       
  • ‘Click chemistry’ synthesis of
           1-(α-d-mannopyranosyl)-1,2,3-triazoles for inhibition of
           α-mannosidases
    • Abstract: Publication date: 10 April 2015
      Source:Carbohydrate Research, Volume 406
      Author(s): Monika Poláková , Rhiannon Stanton , Iain B.H. Wilson , Ivana Holková , Sergej Šesták , Eva Machová , Zuzana Jandová , Juraj Kóňa
      Three new triazole conjugates derived from d-mannose were synthesized and assayed in in vitro assays to investigate their ability to inhibit α-mannosidase enzymes from the glycoside hydrolase (GH) families 38 and 47. The triazole conjugates were more selective for a GH47 α-mannosidase (Aspergillus saitoi α1,2-mannosidase), showing inhibition at the micromolar level (IC50 values of 50–250 μM), and less potent towards GH38 mannosidases (IC50 values in the range of 0.5–6 mM towards jack bean α-mannosidase or Drosophila melanogaster lysosomal and Golgi α-mannosidases). The highest selectivity ratio [IC50(GH38)/IC50(GH47)] of 100 was exhibited by the phenyltriazole conjugate. To understand structure-activity properties of synthesized compounds, 3-D complexes of inhibitors with α-mannosidases were built using molecular docking calculations.
      Graphical abstract image

      PubDate: 2015-03-09T13:00:35Z
       
  • The application of 2,2,2-trichloroethyl sulfate to the synthesis of
           chondroitin sulfate C and D
    • Abstract: Publication date: 10 April 2015
      Source:Carbohydrate Research, Volume 406
      Author(s): Kenya Matsushita , Tomomi Nakata , Jun-ichi Tamura
      Chondroitin sulfates (CSs) have characteristic bioactivities that depend on sulfation patterns. Chemically synthesized CS oligosaccharides are valuable tools for elucidating the relationship between structures and bioactivities. 2,2,2-Trichloroethyl (TCE) sulfated sugars are highly soluble in nonpolar solvents, which is useful for the synthesis of sulfated oligosaccharides. We herein synthesized CS-C [βGalNAc6S(1–4)βGlcA] (1) and CS-D [βGalNAc6S(1–4)βGlcA2S] (2) disaccharides that possessed sulfate groups by TCE sulfation at O-6 of GalNAc and an additional sulfate group at O-2 of GlcA, respectively. We revealed the superior functionalities of TCE sulfates during the synthesis of CS-C and -D, despite the unwanted side reactions in the acetamido-containing substrate.
      Graphical abstract image

      PubDate: 2015-03-09T13:00:35Z
       
  • Ruthenium catalyzed synthesis of 2,3-unsaturated C-glycosides from glycals
    • Abstract: Publication date: 10 April 2015
      Source:Carbohydrate Research, Volume 406
      Author(s): Batthula Srinivas , Thurpu Raghavender Reddy , Sudhir Kashyap
      A highly efficient and convenient C-glycosylation method was developed using ruthenium(III) chloride for the synthesis of 2,3-unsaturated C-glycosides. Various nucleophiles such as allyl trimethylsilane, triethylsilane, trimethylsilyl cyanide, trimethylsilyl azide and heterocycles such as thiophene and furan reacted smoothly with glycals in the presence of catalytic amount of ruthenium trichloride under mild reaction conditions.
      Graphical abstract image

      PubDate: 2015-03-09T13:00:35Z
       
  • A linear synthesis of gemcitabine
    • Abstract: Publication date: 10 April 2015
      Source:Carbohydrate Research, Volume 406
      Author(s): Kylie Brown , Alex Weymouth-Wilson , Bruno Linclau
      Gemcitabine, 2′-deoxy-2′,2′-difluorocytidine, is currently prescribed against a number of cancers. Here we report a linear synthesis of gemcitabine with a high-yielding direct conversion of 3,5-di-O-benzoyl-2-deoxy-2,2-difluororibose into the corresponding glycosyl urea as the key step, followed by conventional conversion to the cytosine base via the uracil derivative. The process proceeded with modest anomeric selectivity.
      Graphical abstract image

      PubDate: 2015-02-13T06:44:34Z
       
 
 
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