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Carbohydrate Research

Chisa Aoki, Yoshihiro Takeuchi, Kenjirou Higashi, Yuta Okamoto, Akihito Nakanishi, Mahamadou Tandia, Jun Uzawa, Keisuke Ueda, Kunikazu Moribe
We report the full assignment of (1)H and (13)C NMR signals belonging to α-glucosyl rhoifolin (Rhf-G), a novel transglycosylated compound synthesized from a flavone glycoside, rhoifolin, as well as its chemical structure. Furthermore, we report the complete NMR signal assignment for another transglycosylated compound, α-glucosyl rutin (Rutin-G), as the signals corresponding to its sugar moieties had not been identified. Electrospray ionization-mass spectrometry along with multiple NMR methods revealed that Rhf-G possesses three sugar moieties in its chemical structure...
March 16, 2017: Carbohydrate Research
Giorgio Catelani, Felicia D'Andrea, Lorenzo Guazzelli, Alessio Griselli, Nicola Testi, Maria Assunta Chiacchio, Laura Legnani, Lucio Toma
Carbohydrate mimics have been studied for a long time as useful sugar substitutes, both in the investigation of biological events and in the treatment of sugar-related diseases. Here we report further evaluation of the capabilities of inositols as carbohydrate substitutes. The conformational features of an inositol-model of a simplified repeating unit corresponding to the capsular polysaccharide of Streptococcus pneumoniae 19F has been evaluated by computational analysis, and compared to the native repeating unit...
March 14, 2017: Carbohydrate Research
Michael Schalli, Christina Tysoe, Roland Fischer, Bettina M Pabst, Martin Thonhofer, Eduard Paschke, Tanja Rappitsch, Arnold E Stütz, Marion Tschernutter, Werner Windischhofer, Stephen G Withers
From 1,2;3,4-di-O-isopropylidene-α-D-galactopyranose, a series of highly functionalized (hydroxymethyl)cyclopentanes was easily available. In line with reports by Reymond and Jäger on similar structures, these amine containing basic carbasugars are potent inhibitors of β-D-galactosidases and, for the first time, could be shown to act as pharmacological chaperones for GM1-gangliosidosis-associated lysosomal acid β-galactosidase mutant R201C, thus representing a new structural type of pharmacological chaperones for this lysosomal storage disease...
March 11, 2017: Carbohydrate Research
Zachary D Herde, Prathap D John, Dania Alvarez-Fonseca, Jagannadh Satyavolu, Christopher T Burns
The stereoselective peracetylation of α-d-xylose (1) and α-l-arabinose (4) using a combination of triethylamine and acetic anhydride in the presence or absence of a catalytic amount of dimethylaminopyridine (DMAP) is described. The peracetylated d-xylose and l-arabinose alpha pyranose anomers 2α and 5α are obtained in 97% and 56% yields respectively. The peracetylated d-xylose beta pyranose anomer 2β is obtained in 71% yield through simple modification of the reaction conditions. Details regarding synthesis and isolation optimization studies under different conditions are presented below...
March 10, 2017: Carbohydrate Research
Matthias Frommhagen, Gijs van Erven, Mark Sanders, Willem J H van Berkel, Mirjam A Kabel, Harry Gruppen
Lytic polysaccharide monooxygenases (LPMOs) are able to cleave recalcitrant polysaccharides, such as cellulose, by oxidizing the C1 and/or C4 atoms. The analysis of the resulting products requires a variety of analytical techniques. Up to now, these techniques mainly focused on the identification of non-oxidized and C1-oxidized oligosaccharides. The analysis of C4-oxidized gluco-oligosaccharides is mostly performed by using high pressure anion exchange chromatography (HPAEC). However, the alkaline conditions used during HPAEC analysis lead to tautomerization of C4-oxidized gluco-oligosaccharides, which limits the use of this technique...
March 6, 2017: Carbohydrate Research
Dongyue Wang, Weiwei Zhuge, Zhongwu Guo, Guofeng Gu
A disaccharide repeating unit of the O-antigen from Burkholderia ambifaria, 6-deoxy-β-d-Alt-(1 → 4)-α-d-Rha-O(CH2)3NH2 (1), and its dimer and trimer, 6-deoxy-β-d-Alt-(1 → 4)-α-d-Rha-(1 → 3)-6-deoxy-β-d-Alt-(1 → 4)-α-d-Rha-O(CH2)3NH2 (2) and 6-deoxy-β-d-Alt-(1 → 4)-α-d-Rha-(1 → 3)-6-deoxy-β-d-Alt-(1 → 4)-α-d-Rha-(1 → 3)-6-deoxy-β-d-Alt-(1 → 4)-α-d-Rha-O(CH2)3NH2 (3), were synthesized via a convergent strategy. The key disaccharyl thioglycoside 4 as a glycosyl donor was stereoselectively assembled by glycosylation of rhammnosyl acceptor 5 with 6-deoxy-altrosyl trichloroacetimidate donor 6b...
March 6, 2017: Carbohydrate Research
René Lebl, Martin Thonhofer, Christina Tysoe, Bettina M Pabst, Michael Schalli, Patrick Weber, Eduard Paschke, Arnold E Stütz, Marion Tschernutter, Werner Windischhofer, Stephen G Withers
By Morita-Baylis-Hillman reaction of 2,3-O-isopropylidene-D-glyceraldehyde with α,β-unsaturated carbonyl as well as hetero analogous carbonyl compounds such as acrylonitrile, suitable precursors of isofagomine and of 4-epi-isofagomine are available. Elaboration of the structures by amine introduction, followed by intramolecular ring closure and subsequent hydroboration of the double bond provides 4-epi-isofagomine derivatives featuring chain extensions at C-5a which are determined by the structures of the carbonyl compounds employed...
March 6, 2017: Carbohydrate Research
Annette M Bodenheimer, William B O'Dell, Christopher B Stanley, Flora Meilleur
Sensitivity to hydrogen/deuterium and lack of observable radiation damage makes cold neutrons an ideal probe the structural studies of proteins with highly photosensitive groups such as the copper center of lytic polysaccharide monooxygenases (LPMOs) and flavin adenine dinucleotide (FAD) and heme redox cofactors of cellobiose dehydrogenases (CDHs). Here, neutron crystallography and small-angle neutron scattering are used to investigate Neurospora crassa LPMO9D (NcLPMO9D) and CDHIIA (NcCDHIIA), respectively...
March 4, 2017: Carbohydrate Research
Santosh Ramdas Borkar, Indrapal Singh Aidhen
Total synthesis of naturally occurring Oxylipin has been achieved from open chain gluco-configured building block which is readily assembled from inexpensive and commercially available D-(+)-gluconolactone. Grignard reaction and Wittig olefination reactions are key steps for the requisite CC bond formation.
March 3, 2017: Carbohydrate Research
S Raghavendra, Krishnaji Tadiparthi, J S Yadav
The total syntheses of natural products Prelactone-V and Prelactone-B have been accomplished by a novel Chiron approach starting from d-glucose. The synthesis involves isopropylidene acetal formation of d-glucose using Poly(4-vinylpyridine) supported iodine as a catalyst, Tebbe olefination, Grignard reaction, Wittig olefination, selective mono deprotection of acetal using PMA/SiO2, hydrogenation and anti-1,3-diol formation are as key steps.
February 28, 2017: Carbohydrate Research
Liming Wang, Zengshang Wang, Sheng Su, Ying Xing, Yali Li, Ming Li, Jiangyun Liu, Shilin Yang
An array of oleanolic acid-type saponins based on β-hederin has been synthesized in a linear or one-pot manner. The cell viability assays indicate that synthetic saponins show antiproliferation activities in three cancer cell lines with IC50 values of 2.4-15.1 μM and hederacolchiside A1 being the most potent. The results demonstrate that the type of terminal monosaccharides and linkage position have apparent effects on cytotoxicities and selectivities of these saponins against cancer cell lines tested. This study is helpful for future development of more potent anticancer leads...
February 28, 2017: Carbohydrate Research
Rémi Chambon, Stéphanie Pradeau, Sébastien Fort, Sylvain Cottaz, Sylvie Armand
Lipo-chitinoligosaccharides (LCOs) are key molecules for the establishment of plant-microorganisms symbiosis. Interactions of leguminous crops with nitrogen-fixing rhizobial bacteria involve Nod factors, while Myc-LCOs improve the association of most plants with arbuscular mycorrhizal fungi. Both Nod factors and Myc-LCOs are composed of a chitinoligosaccharide fatty acylated at the non-reducing end accompanied with various substituting groups. One straightforward way to access LCOs is starting from chitin hydrolysate, an abundant polysaccharide found in crustacean shells, followed by regioselective enzymatic cleavage of an acetyl group from the non-reducing end of chitin tetra- or pentaose, and subsequent chemical introduction of N-acyl group...
February 27, 2017: Carbohydrate Research
D Jamin Keith, Steven D Townsend
A series of carbohydrate 2-azido-1-nitrate-esters, protected at the C-3, C-4, and C-6 positions, were hydrolyzed thermally under reagent free conditions. This preliminary result was extended to direct exchange of the 1-nitrate-ester modality for alcohol, alkoxy, and azide coupling partners with minimal purification. While direct glycosylation of nitrate esters ultimately proved unsuccessful, we have demonstrated that an anomeric nitrate-ester can be converted directly to a trichloroacetimidate in a short and simple one-pot procedure, bypassing lower yielding two-step sequences...
February 24, 2017: Carbohydrate Research
Gaston Courtade, Simone Balzer Le, Gerd Inger Sætrom, Trygve Brautaset, Finn L Aachmann
Lytic polysaccharide monooxygenases (LPMOs) are key enzymatic players of lignocellulosic biomass degradation processes. As such, they have been introduced in cellulolytic cocktails for more efficient and less expensive lignocellulose saccharification. The recombinant production of LPMOs in bacteria for scientific investigations using vectors typically based on the T7 and lacUV5 promoters has been hampered by low yields. Reasons for this have been catabolite repression when producing the proteins in defined media with glucose as the sole carbon source, as well as the lack of an inducible expression system that allows controlled production of LPMOs that are correctly processed during translocation to the periplasmic space...
February 14, 2017: Carbohydrate Research
Hongjun Zang, Songbai Yu, Pengfei Yu, Hongying Ding, Yannan Du, Yuchan Yang, Yiwen Zhang
Here, N-acetyl-d-glucosamine (GlcNAc), the monomer composing the second most abundant biopolymer, chitin, was efficiently converted into 5-hydroxymethylfurfural (5-HMF) using ionic liquid (IL) catalysts in a water/dimethyl sulfoxide (DMSO) mixture solvent. Various reaction parameters, including reaction temperature and time, DMSO/water mass ratios and catalyst dosage were optimized. A series of ILs with different structures were analyzed to explore their impact on GlcNAc conversion. The substrate scope was expanded from GlcNAc to d-glucosamine, chitin, chitosan and monosaccharides, although 5-HMF yields obtained from polymers and other monosaccharides were generally lower than those from GlcNAc...
February 11, 2017: Carbohydrate Research
Gerrit J Gerwig, Evelien M Te Poele, Lubbert Dijkhuizen, Johannis P Kamerling
The wild-type Gtf180-ΔN glucansucrase enzyme from Lactobacillus reuteri 180 was found to catalyze the α-glucosylation of the steviol glycoside rebaudioside A, using sucrose as glucosyl donor in a transglucosylation process. Structural analysis of the formed products by MALDI-TOF mass spectrometry, methylation analysis and NMR spectroscopy showed that rebaudioside A is specifically α-d-glucosylated at the steviol C-19 β-d-glucosyl moiety (55% conversion). The main product is a mono-(α1 → 6)-glucosylated derivative (RebA-G1)...
February 22, 2017: Carbohydrate Research
Kelly M Craft, Steven D Townsend
Human milk oligosaccharides (HMOs) are the third largest macromolecular component of breast milk and offer infants numerous health benefits, most of which stem from the development of a healthy microbiome. Characterization, quantification, and chemical derivatization of HMOs remains a frontier issue in glycobiology due to the challenge of isolating appreciable quantities of homogenous HMOs from breast milk. Herein, we report the synthesis of the human milk tetrasaccharide lacto-N-tetraose (LNT). LNT is ubiquitous in human breast milk as it is a core structure common to longer-chain HMOs and many glycolipids...
February 22, 2017: Carbohydrate Research
Evgeny Vinogradov, Frank St Michael, Kiyonobu Homma, Ashu Sharma, Andrew D Cox
Fusobacterium nucleatum is an anaerobic bacterium found in the human mouth where it causes periodontitis. Recently, it has been gaining attention as a potential causative agent for colorectal cancer and is strongly linked with pregnancy complications including pre-term and still births. Little is known about virulence factors of this organism and thus we have initiated studies to examine the bacterial surface glycochemistry. Consistent with a recent paper suggesting that F. nucleatum strain 10593 can synthesize sialic acid, a staining technique identified sialic acid on the bacterial surface...
February 22, 2017: Carbohydrate Research
Sea-Hun Oh, BoMi Ryu, Dai-Hung Ngo, Won-Suk Kim, Dong Gyu Kim, Se-Kwon Kim
Positive charges of chitooligomer (COS) enable COS to interact with negatively charged anionic groups on the cell surface resulting in an improvement in the biological activity of COS and its derivatives. In this study, 4-hydroxybenzaldehyde-COS (HB-COS) was synthesized and investigated for its abilities against H2O2-induced oxidative stress in microglia BV-2 cells. Under oxidative stress, HB-COS significantly attenuated reactive oxygen species (ROS) generation and DNA oxidation, and upregulated the protein levels of antioxidative enzymes...
February 22, 2017: Carbohydrate Research
Kevin Sheerin, Lorenzo Guazzelli, Stefan Oscarson
Crystalline acetylated ethyl 2-azido-2-deoxy-1-thio-α-d-cellobioside has been prepared on a multigram scale from cellobiose in an overall yield of 23% with no chromatography required and converted after deacetylation into the 4',6'-O-benzylidene and 4',6'-O-benzylidene-6-O-TBDMS protected derivatives. Applying a number of regioselective benzylation methods on these gave access to a variety of regioselectively protected derivatives, both mono-ols (2'- and 3-OH), diols (2',6-, 2',3-, and 3,6-di-OH), and triols (2',3,6- and 2',3',3-tri-OH)...
February 22, 2017: Carbohydrate Research
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