Crystal and molecular structures of two unsaturated monosaccharides: methyl 6-(N-benzenesulfonylamino)-N,O-isopropylidene-2,3,6,8-tetradeoxy-α-D-erythrooct-2-enopyranos-4-uloside,and 1,1-O,O-ethylidene-3,4-dideoxy-D,L-hex-3-enoz-2-ulopyranos-5-ulose

Methyl 6-(N-benzenesulfonylamino)-N,O-isopropylidene-2,3,6,8-tetradeoxy--d-erythrooct-2-enopyranos-4-uloside, C₁₈H₂₃N₁O₆S₁, (3) crystallizes in the orthorhombic space groupP2₁2₁2₁. The unit cell parameters are:a=7.839(2),b=10.111(2),c=24.217(5) Å. The dihydropyranone ring adopts a deformed sofa conformation with the O5 atom deviating 0.586(2) Å from the least-squares plane and the -face of the carbonyl group shielded by the terminal (C8) methyl group. 1,1-O,O-Ethylidene-3,4-dideoxy-d,l-hex-3-enoz-2-ulopyranos-5-ulose, C₈H₁₀O₅, (6) crystallizes in the monoclinic space groupP2₁/n. The unit cell parameters are:a=6.310(1),b=18.656(3),c=7.604(1) Å, =106.01(1)°. The dihydropyranone ring adopts a deformed sofa conformation with O6 atom deviating 0.482(1) Å from the leastsquares plane and the hydroxy and dioxolanyl substituents are in pseudoaxial and pseudoequatorial positions, respectively. The average planes of six-membered and five-membered rings are approximately coplanar.     

Synthesis ofN-chioroacetyl-β-glycopyranosylamines,derivatives of monosaccharides and lactose

N-Chloroacetyl--glycopyranosylimines were synthesized from various monosaccharide (hexoses, pentoses, deoxysugars, uronic acids, and sugar phosphates) and a disaccharide (lactose) byN-acylation of the corresponding -glycosylamines with chloroacetic anhydride in DMF In some cases, treatment of rnonosacc harides with NH₃ in the presence of (NH₄)₂CO₃ in MeOH or aqueous MeOH was more efficient than the methods previously described, as it gave -glycosylarnines in higher yields.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 7, pp. 1848–1851, July, 1996.     

Effect of Sonication Treatment and Maceration Time in the Extraction of Polysaccharide Compounds during Red Wine Vinification

The application of high-power ultrasounds (US) at 28 kHz to the crushed grapes and the use of different pomace contact times caused changes in the content and composition of monosaccharides and polysaccharides in the musts and wines. These differences were maintained from the moment of pressing (end of maceration) until the end of the alcoholic fermentation. The US increased the content of monosaccharides and polysaccharides in the musts by facilitating their extraction from the solid parts during maceration. The application of medium maceration time (3 days) to sonicated grapes led to an extraction of polysaccharides rich in arabinose and galactose, rhamnogalacturonan type II (RG-II) and mannoproteins (MP), similar to that observed in the control wines made with an extended maceration of 7 days (968.21 vs. 1029.45; 895.04 vs. 1700.50; 356.81 vs. 343.95, respectively). This fact was attributed to a higher extraction in the must during the sonication process and to an important release of pectic polysaccharides during the pressing of the sonicated pomace, which is reported here for the first time. Therefore, the US technology could be useful for increasing the polysaccharide content in the wines or for reducing the maceration time needed to achieve certain levels of wine polysaccharides.     

A capillary electrophoresis method for the determination of soluble monosaccharides in Ginkgo biloba leaves

A method for the simultaneous determination of six monosaccharides by pre-column derivatization with 1-phenyl-3-methyl-5-pyrazolone and capillary electrophoresis was developed in this work. The derivatization (i.e., reaction temperature, capillary electrophoresis duration, and extraction number) and separation (i.e., pH and buffer concentration) conditions for capillary electrophoresis were optimized. Results showed that the limits of detection under optimal conditions were in the range of 0.036–0.35 mg/L with a mean correlation coefficient >0.99. The recoveries were in the range of 87.3–108.49%, and the relative standard deviations of intra- and inter-day variations were in the ranges of 2.2–3.8 and 3.2–5.0%, respectively. The method was successfully applied to the analysis of six free monosaccharides in three types of Ginkgo biloba leaves.     

Artificial Cysteine S‐Glycosylation Induced by Per‐O‐Acetylated Unnatural Monosaccharides during Metabolic Glycan Labeling

The unexpected, non‐enzymatic S‐glycosylation of cysteine residues in various proteins by per‐O‐acetylated monosaccharides is described. This artificial S‐glycosylation greatly compromises the specificity and validity of metabolic glycan labeling in living cells by per‐O‐acetylated azido and alkynyl sugars, which has been overlooked in the field for decades. It is demonstrated that the use of unacetylated unnatural sugars can avoid the artifact formation and a corrected list of O‐GlcNAcylated proteins and O‐GlcNAc sites in HeLa cells has been assembled by using N‐azidoacetylgalactosamine (GalNAz).     

Synthesis of 2-deoxy-α-DAH based on diazo chemistry by insertion reactions of 2-diazo-3-deoxy- -arabino-heptulosonate derivatives mediated by rhodium(II)

The synthesis of 2-deoxy-α-DAH (2) is described based on the use of diazo chemistry as previously reported by us during the synthesis of the corresponding 2-deoxy-KDO. Initially, the -arabino-aldehydo sugar derivative 3 was reacted with ethyl diazoacetate, using diethyl zinc as promoter. The corresponding β-hydroxy-α-diazo ester 4, obtained in very good yield, was transformed into the corresponding 2-diazo-3-deoxy-heptulosonate derivative 10, which was subjected to the action of rhodium(II). However, the major compound obtained in this reaction was the C-glycofuranoside 12 by the interaction of the benzyl protecting group employed at the OH of C-4 with the carbenoid generated at C-2. To avoid this undesired insertion reaction, aldehyde 13 was selected as a suitable starting material and, following the same chemistry than for 3, diazo 19 was efficiently synthesized. Finally, the intramolecular OH insertion mediated by rhodium(II) of 19 provided the targeted 2-deoxy-DAH derivative 21 in a reasonable good yield, which was finally transformed into the potassium salt of 2-deoxy-α-DAH 2.     

Monosaccharides as internal probes for the determination of the absolute configuration of 2-butanol

D-Glucose, D-mannose and L-rhamnose were reacted with a racemic mixture of 2-butanol, and the resulting alpha-glycosides were analyzed by 1H NMR with COSY and NOESY experiments. Conformational analysis of alpha-glycosidic bonds performed with molecular modeling and appropriate heteronuclear long-range coupling measurements and combined with analysis of dipolar couplings observed in NOESY spectra allowed the assignment of absolute configuration in the aglycones of elucidated alpha-glycosides.     

结核分枝杆菌细胞单糖的毛细管气相色谱分析

本文研究了一种结核分枝杆菌细胞单糖的毛细管气相色谱分析方法。测定了11种(株)标准分枝杆菌,2株人工培养耐药株及11株临床分枝杆菌菌株的细胞单糖成分。实验结果表明,分枝杆菌细胞单糖的分析,不仅可以对分枝杆菌进行鉴定,而且可以提供与分枝杆菌的毒力和耐药性有关的特征色谱峰。     

气相气谱测定土壤中的糖

气相气谱测定土壤中的糖王彦中,穆惠玲,仇津苹（南开大学中心实验室天津３０００７１）１前言糖是土壤有机质的重要组成,它的测定对认识土壤质量无疑是重要的。以往大多仅测定土壤有机质总量,而单独测定其中糖含量的报道甚少￣［１～３］,在国内尚未见到。近年来气相...     

A theoretical study of vibrational spectra of tetranitrate-methyl-β-D-glucopyranoside and 2,3-di-O-nitro-methyl-β-D-glucopyranoside

Coupled calculations were carried out of normal vibration frequencies from the point of view of the valence-force field scheme and of absolute IR band intensities by the CNDO/2 method for the tetranitrate-methyl-β-D-glucopyranoside molecule. A good agreement was achieved with the experiments. Normal coordinate analysis was made for 2,3-di-O-nitro-methyl-β-D-glucopyranoside molecule with force constants obtained for the tetra-nitrate-methyl-β-D-glucopyranoside. Before proceeding to the calculation of the spectra of such complex molecules of nitrates of monosaccharides, a complete experimental and theoretical investigation was performed of the vibrational spectra of methylnitrate, which made it possible to determine the deficit of force constants for the calculations of the spectra of nitrosubstituted glucopyranosides. Detailed interpretations of the observable IR spectra of both the nitro-glucopyranosides compounds considered are given. The absorption spectra sensitivity to the spot of the nitrate group localization was discovered. Special attention was focused on analyzing the spectra of nitrates of saccharides for the characteristic split of the band due to the asymmetric stretching vibrations of the ONO₂ groups in the region of 1600–1700 cm⁻¹.