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Carbohydrate Research

Zubeda Begum, G Shankar, K Sirisha, B V Subba Reddy
A highly efficient oxidative C2-aroyloxylation of D-glucal with aromatic carboxylic acids has been achieved for the first time using 5 mol% Pd(OAc)2 and 1 equiv of PhI(OAc)2 to produce C2-aroyloxyglycals in good yields. The use of excess of PhI(OAc)2 (2 equiv) provides C2-acyloxyglycal exclusively.
March 12, 2018: Carbohydrate Research
Carlos-A Bernal, Leonardo Castellanos, Diana M Aragón, Diana Martínez-Matamoros, Carlos Jiménez, Yolima Baena, Freddy A Ramos
The fruit of Physalis peruviana is widely used in traditional Colombian medicine as an antidiabetic treatment. The aim of the study reported here was to identify the compounds responsible for the hypoglycemic activity using the α-amylase inhibition test. Bioguided fractionation of a dichloromethane extract of the sticky exudate that covers the fruit allowed the isolation and identification of three new sucrose esters, named as peruvioses C-E (1-3), along with the known peruvioses A (6), B (5) and F (4), the structures of which were elucidated by extensive NMR and MS experiments...
March 9, 2018: Carbohydrate Research
Maxim S Kokoulin, Anatoly I Kalinovsky, Lyudmila A Romanenko, Valery V Mikhailov
The O-polysaccharide was isolated from the lipopolysaccharide of a marine bacterium Pseudomonas glareae KMM 9500T and studied by chemical methods along with 1D and 2D1 H and13 C NMR spectroscopy including1 H,1 H-TOCSY,1 H,1 H-COSY,1 H,1 H-ROESY,1 H,13 C-HSQC and1 H,13 C-HMBC experiments. The O-polysaccharide was found to consist of linear tetrasaccharide repeating units constituted by D-glucuronic acid (D-GlcA), L-rhamnose (L-Rha), D-glucose (D-Glc) and 5-acetamido-7,9-O-[(S)-1-carboxyethylidene]-3,5-dideoxy-L-glycero-L-manno-non-2-ulosonic acid (Sug7,9(S-Pyr)), partially O-acetylated at position 8 (∼70%): →4)-α-D-GlcpA-(1→3)-β-L-Rhap-(1→4)-β-D-Glcp-(1→4)-β-Sugp8Ac(∼70%)7,9(S-Pyr)-(2→...
March 8, 2018: Carbohydrate Research
Zhiqiang Jiang, Xiaoyan Dong, Yan Sun
Amyloid β-protein (Aβ) aggregation is crucial for the pathogenesis of Alzheimer's disease, and surface charge of nanoparticles (NPs) has been recognized as an important factor influencing Aβ aggregation. Herein, we report a systematic study on the issue with a series of self-assembled chitosan-hyaluronic acid composite (CH) NPs of different surface charges (CH1 to CH7, zeta potentials from +38 to -35 mV). Both the positive and negative CH NPs inhibited Aβ aggregation and the inhibitory effect increased with increasing the surface charges density...
March 8, 2018: Carbohydrate Research
Shiqiang Yan, Sumei Ren, Ning Ding, Yingxia Li
Starting from readily available vanillin and α-D-acetobromo glucose, two natural acylated phenolic glycosides vitexnegheteroin A and ovatoside D were synthesized for the first time in 4 steps with overall yields of 54% and 65%, respectively. The key steps involve the directly regioselective O-6 acylation of vanillin β-D-glucopyranoside with acyl chlorides, and simultaneous removal of the allyl protecting groups on the phenolic acid moiety and reduction of the aldehyde in the aglycon moiety by using Pd(PPh)3 -NaBH4 system in one pot...
March 2, 2018: Carbohydrate Research
Olga V Sizova, Alexander S Shashkov, Anna N Kondakova, Yuriy A Knirel, Rima Z Shaikhutdinova, Sergei A Ivanov, Angelina A Kislichkina, Lidia A Kadnikova, Aleksandr G Bogun, Svetlana V Dentovskaya
Lipopolysaccharide was isolated from bacteria Yersinia intermedia H9-36/83 (O:17) and degraded with mild acid to give an O-specific polysaccharide, which was isolated by GPC on Sephadex G-50 and studied by sugar analysis and 1D and 2D NMR spectroscopy. The polysaccharide was found to contain 3-deoxy-3-[(R)-3-hydroxybutanoylamino]-d-fucose (d-Fuc3NR3Hb) and the following structure of the heptasaccharide repeating unit was established: The structure established is consistent with the gene content of the O-antigen gene cluster...
February 28, 2018: Carbohydrate Research
Yiren Xu, Tianheng Xu, Jianjun Zhang
Synthesis of the 6-deoxy-talose (6-dTal) containing tetrasaccharide, naturally found in Franconibacter helveticus LMG23732T, has been described. The synthetic method utilized an allyloxyethylidene group for protecting the 1-OH and 2-OH groups of rhamnopyranose and a redox reaction for synthesizing 6-deoxy talose, which eventually formed a disaccharide containing α-Glcp-(1→2)-6dTalp configured glycosidic bonds using a [2 + 2] synthetic strategy.
February 26, 2018: Carbohydrate Research
Bence Kutus, Csilla Dudás, Gábor Peintler, István Pálinkó, Pál Sipos
The calcium sugar carboxylate interactions in hyperalkaline solutions are of relevance in radioactive waste repositories and in certain industrial processes. The complex formation between L-gulonate and Ca2+ ions was studied in strongly alkaline medium at 25 °C and 1 M ionic strength and was compared with previous results reported for D-gluconate and D-heptagluconate. The deprotonation of the ligand was confirmed by potentiometric and13 C NMR spectroscopic measurements. Pronounced pH effects were seen in the presence of Ca2+ indicating strong complex formation...
February 23, 2018: Carbohydrate Research
Katarzyna Sidoryk, Piotr Cmoch, Marta Świtalska, Bartosz Trzaskowski, Joanna Wietrzyk, Marcin Cybulski
An efficient methodology of the glycosylation process of a secondary plant metabolite (R-Danshensu) and its enantiomer by sugar and 2-deoxy sugar donors was developed. The overall synthesis of the new sugar derivatives involved two steps, starting from the previously synthesized protected R and S Danshensu (1 and 2). The deoxy sugar derivatives of R and S Danshensu were obtained from available tri-O-acetyl-2-deoxy-D-glucal and di-O-acetyl-2-deoxy-D-ramnal. The direct glycosylation of 1 and 2 using glycal activation by an acid catalyst in all cases led to the α-anomers of deoxy sugar derivatives with good yields...
February 23, 2018: Carbohydrate Research
Qiwei Wang, Chen Ma, Xueyan Li, Xiaofen Wang, Ruixue Rong, Chao Wei, Pingzhu Zhang, Xiaoliu Li
A series of novel, sugar or azasugar modified anthra[1,2-d] imidazole-6,11-dione derivatives, with different side chain were synthesized, using the synthetic route of imidazole cyclization reaction of 1,2-diaminoanthraquinone with various sugar (azasugar)-derived aldehydes, and imidazole cyclization reaction of 1,2-diaminoanthraquinone with chloroacetic acid and then followed by the nucleophilic substitution of N-alkylamino azasugar. Their biological activities against HIV-RT and cytotoxic activities against A549, Hela and MCF-7 cells were preliminary evaluated, most compounds showed similar HIV-RT inhibition to the control drug (AZT)...
February 20, 2018: Carbohydrate Research
Tímea Kaszás, Anton Ivanov, Marietta Tóth, Peter Ehlers, Peter Langer, László Somsák
Palladium-catalyzed cross-couplings of O-peracylated and O-permethylated 2,6-anhydro-aldose tosylhydrazones with aryl halides were studied under thermic conditions in the presence of LiOtBu and phosphine ligands. The reactions gave the corresponding aryl substituted exo-glycals as mixtures of diastereomers in 11-75% yields. The transformations represent a new access to these types of glycomimetic compounds. The double bond of some aryl substituted exo-glycals was saturated to give good yields of benzylic C-glycosyl derivatives...
February 19, 2018: Carbohydrate Research
Haoran Xing, Varoujan A Yaylayan
Although chemical reactions driven by mechanical force is emerging as a promising tool in the field of physical sciences, its applications in the area of food sciences are not reported. In this paper, we propose ball milling as an efficient tool for the controlled generation of fructooligosaccharide (FOS) mixtures from inulin with a degree of polymerization (dp) ranging between 4 and 7. The addition of catalytic amounts of AlCl3 together with ball milling (30 min, at 30 Hz) generated mixtures rich in dehydrated disaccharides such as di-D-fructose dianhydrides...
February 19, 2018: Carbohydrate Research
Sof'ya N Senchenkova, Wenqi Hou, Olesya I Naumenko, Peng Geng, Alexander S Shashkov, Andrei V Perepelov, Bin Yang, Yuriy A Knirel
An O-specific polysaccharide was isolated by mild acid degradation of the lipopolysaccharide of Escherichia coli O33 followed by gel-permeation chromatography on Sephadex G-50. The polysaccharide was found to contain glycerol 2-phosphate (Gro-2-P), and the following structure of its tetrasaccharide repeat was established by sugar analysis, dephosphorylation, and 1D and 2D1 H and13 C NMR spectroscopy: The O33-antigen gene cluster was analyzed and found to be essentially consistent with the O-polysaccharide structure...
February 17, 2018: Carbohydrate Research
Tiezheng Li, Chao Li, David N Quan, William E Bentley, Lai-Xi Wang
Chemoenzymatic glycan remodeling of antibodies using an endoglycosidase and its mutant is emerging as an attractive approach for producing homogeneous antibody glycoforms. We report in this paper a site-specific covalent immobilization of the endoglycosidases (Endo-S2 and its glycosynthase mutant D184M) using a recombinant microbial transglutaminase (MTG) and evaluation of the immobilized enzymes in deglycosylation and glycosylation of a therapeutic antibody. The site-specific covalent immobilization was achieved by introduction of a Q-tag at the C-terminus of the recombinant enzymes followed by conjugation of the enzymes to a primary amine-containing solid support through MTG-catalyzed transglutamination...
February 15, 2018: Carbohydrate Research
Yoshitsugu Amano, Masaki Nakamura, Shinya Shiraishi, Naoto Chigira, Nobuya Shiozawa, Masahito Hagio, Tomohiro Yano, Teruaki Hasegawa
We developed new gossypol (Gos)-based glycoconjugates through dehydration condensation of native Gos and chemically modified glycosides having aminooxy groups. The resultant glycoconjugates (glycoGos) were resistant to hydrolysis, although they were light-sensitive and slowly decomposed even under indoor lighting. The glycoGos also exhibited improved water solubility compared with native Gos, but their saturated concentrations in water were still low (6.4-17 μM), due to their hydrophobic naphthyl rings. We also carried out WST-8 assays to assess the anticancer activity of the glycoGos on DLD-1 and HepG2 cells and found that the glycoGos having β-lactosides and having β-galactosides (specific ligands for asialoglycoprotein receptors) showed enhanced anticancer activity on HepG2 cells...
February 14, 2018: Carbohydrate Research
Hong-Zhan Li, Jie Ding, Chun-Ru Cheng, Yue Chen, Xing-Yong Liang
We describe a β-L-arabinofuranosylation method by employing the 5-O-(2-pyridinecarbonyl)-L-arabinofuranosyl trichloroacetimidate 10 as a donor. This approach allows a wide range of acceptor substrates, especially amino acid acceptors, to be used. Stereoselective synthesis of β-(1,4)-L-arabinofuranosyl-(2S, 4R)-4-hydroxy-L-proline (β-L-Araf-L-Hyp4 ) and its dimer is achieved readily by this method. Both the stereoselectivities and yields of the reactions are excellent. To demonstrate the utility of this methodology, the preparation of a trisaccharide in a one-pot manner was carried out...
February 13, 2018: Carbohydrate Research
Elena V Stepanova, Marina O Nagornaya, Victor D Filimonov, Rashid R Valiev, Maxim L Belyanin, Anna K Drozdova, Victor N Cherepanov
In the present work we report that acetyl groups of per - acetylated aryl glycosides have different reactivity during the acidic deacetylation using HCl/EtOH in CHCl3, which leads to preferential deacetylation at O-3, O-4 and O-6. Thereby, the one-step preparation of 2-O-acetyl aryl glycosides with simple aglycon was accomplished for the first time. It was proved that the found reagent is to be general and unique for the preparation of series of 2-О-acetyl aryl glycosides. We have determined the influence of both carbohydrate moiety and the aglycon on the selectivity of deacetylation reaction by kinetic experiments...
February 12, 2018: Carbohydrate Research
Martin Kaufmann, Sophie Krüger, Clemens Mügge, Lothar W Kroh
Analyzing classical model reaction systems of Amadori rearrangement products (ARP) it became apparent that the formation of 3-deoxy-d-threo-hexo-2-ulose (3-deoxygalactosone, 3-DGal) during the degradation of ARPs is highly dependent on pH and the amino acid residue of the respective ARP. Based on a detailed analysis of the NMR chemical shifts of the sugar moieties of different ARPs, it could be derived that the formation of 3-DGal is sensitive to the stability of a co-operative hydrogen bond network which involves HO-C3, the deprotonated carboxyl functionality and the protonated amino nitrogen of the amino acid substituent...
February 12, 2018: Carbohydrate Research
Tomoya Takashima, Takayuki Ohnuma, Tamo Fukamizo
CJP-4 is a two-domain chitinase from Japanese cedar (Cryptomeria japonica) pollen, consisting of an N-terminal CBM18 domain and a GH19 catalytic domain. The substrate binding to an inactive mutant protein of full-length CJP-4, in which the catalytic acid Glu108 was mutated to glutamine, CJP-4(E108Q), was analyzed by NMR spectroscopy. Based on the chemical shift perturbations of1 H-15 N HSQC signals of Gly26 (CBM18 domain) and Trp185 (GH19 domain), the association constants for individual domains of CJP-4(E108Q) toward soluble chitin hexamer (GlcNAc)6 were determined to be 2300 and 3500 M-1 , respectively...
February 8, 2018: Carbohydrate Research
Matylda Stefaniak, Grzegorz Łopatkiewicz, Magdalena Antkowiak, Jacek Mlynarski
Efficient stereocontrolled synthesis of ladyginoside A isolated from Ladyginia bucharica is described. The presented methodology bases on the β-selective glycosylation to construct oleanate-3-O-β-glycoside from selectively protected d-cellobiose comprising desired β-linkage in carbohydrate unit. By using this procedure, dimethyl ester of ladyginoside A (1) (methyl oleanate 3-O-(β-d-glucopyranosyl)-(1 → 4)-β-d-glucuronide methyl ester) was obtained in 16% overall yield. Elaborated synthesis is also demonstrated as useful methodology en route to saponin 2 with additional glucose unit, namely 3-O-[β-d-glucopyranosyl-(1 → 4)-β-d-glucuronide] oleanolic acid 28-O-β-d-glucopyranosyl ester...
February 8, 2018: Carbohydrate Research
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