氯代脱氧三糖合成的研究

在1:1 C~6H~6-CH~3NO~2, Hg(CN)~2, CaH~2体系中, 蔗糖六乙酸酯和乙酰基糖的溴化物发生缩合反应, 再经过氯化和脱乙酰基得到氯代脱氧三糖. ^1H NMR证明了糖苷键的构型.     

Determination of sucrose by flow injection analysis with fourier transform infrared detection

A new methodology for the determination of sucrose in complex aqueous matrices by flow injection analysis with FTIR detection is presented. The methodology based on the enzymatic hydrolytic cleavage of sucrose by means of invertase to -D-glucose and -D-fructose. A special manifold consisting of two internally coupled injection valves being switched simultaneously is applied to facilitate recording FTIR spectra of the sample before and after the enzymatic reaction. The analytical readout is taken from the resulting difference spectrum obtained by subtracting the FTIR spectra of the sample before and after the reaction. The developed methodology uses a GC-IR software to continuously record the FTIR spectra of the effluent from the manifold. The proposed method gives linear results in the range of 10 to 100 mmol/l and has been successfully applied to the analysis of sucrose in synthetic mixtures as well as in real samples such as soft drinks.     

蔗糖对MO/水立方液晶体系流变性质的影响

主要研究了蔗糖对甘油单油酸脂(monoolein, MO)/水立方液晶体系的流变学性质及其相行为的影响. 根据体系流变性质的变化和偏光显微镜照片, 得出随着蔗糖含量的增加, MO/水体系发生了由反相立方液晶到反相六角状液晶的相转变. 蔗糖与MO分子通过氢键相互作用, 减弱了两亲分子间的静电斥力. 当蔗糖含量增加到一临界值时, 体系的立方结构被破坏, 继续增加蔗糖的含量, 体系就会形成新的反相六角状液晶.     

Rapid Identification of 3,6′-Disinapoyl Sucrose Metabolites in Alzheimer’s Disease Model Mice Using UHPLC–Orbitrap Mass Spectrometry

Alzheimer’s disease (AD) is a degenerative disease of the central nervous system characterized by the progressive impairment of neural activity. Studies have shown that 3,6′-disinapoyl sucrose (DISS) can alleviate the pathological symptoms of AD through the activation of the cAMP/CREB/BDNF signaling pathway. However, the exact biochemical mechanisms of action of DISS are not clear. This study explores metabolism of DISS in an AD mouse model, induced by the microinjection of a lentiviral expression plasmid of the APPswe₆₉₅ gene into CA1 of the hippocampus. After gavage administration of DISS (200 mg/kg), the kidneys, livers, brains, plasma, urine, and feces were collected for UHPLC–Orbitrap mass spectrometry analysis. Twenty metabolites, including the prototype drug of DISS, were positively or tentatively identified based on accurate mass measurements, characteristic fragmentation behaviors, and retention times. Thus, the metabolic pathways of DISS in AD mice were preliminarily elucidated through the identification of metabolites, such as ester bond cleavage, demethoxylation, demethylation, and sinapic acid-related products. Furthermore, differences in the in vivo distribution of several metabolites were observed between the model and sham control groups. These findings can provide a valuable reference for the pharmacological mechanisms and biosafety of DISS.     

Premix Membrane Emulsification: Preparation and Stability of Medium-Chain Triglyceride Emulsions with Droplet Sizes below 100 nm

Premix membrane emulsification is a promising method for the production of colloidal oil-in-water emulsions as drug carrier systems for intravenous administration. The present study investigated the possibility of preparing medium-chain triglyceride emulsions with a mean particle size below 100 nm and a narrow particle size distribution using sucrose laurate as an emulsifier. To manufacture the emulsions, a coarse pre-emulsion was repeatedly extruded through alumina membranes (Anodisc^™) of 200 nm, 100 nm and 20 nm nominal pore size. When Anodisc^™ membranes with 20 nm pore size were employed, nanoemulsions with z-average diameters of about 50 nm to 90 nm and polydispersity indices smaller than 0.08 could be obtained. Particle growth due to Ostwald ripening was observed over 18 weeks of storage. The Ostwald ripening rate linearly depended on the emulsifier concentration and the concentration of free emulsifier, indicating that micelles in the aqueous phase accelerated the Ostwald ripening process. Long-term stability of the nanoemulsions could be achieved by using a minimised emulsifier concentration or by osmotic stabilisation with soybean oil added in a mass ratio of 1:1 to the lipid phase.     

丙烯酸松香蔗糖聚氨酯/聚丙烯酸酯IPN的合成与性能

丙烯酸松香蔗糖聚氨酯/聚丙烯酸酯IPN的合成与性能     

HF/6‐31G* energy surfaces for disaccharide analogs

The HF/6‐31G* level of theory was used to calculate relaxed potential energy surfaces for 12 analogs of disaccharides. The analogs were made by replacing glucose with tetrahydropyran and fructose with 2‐methyltetrahydrofuran. Molecules had zero, one or two anomeric carbon atoms, and di‐axial, axial‐equatorial, and di‐equatorial linkages. Despite the absence of hydroxyl groups, the surfaces account well for conformations that are observed in crystals of the parent disaccharides. Thus, torsional energy and the simple bulk of ring structures are major factors in determining disaccharide conformation. The contour shapes around the global minima depend on the number of anomeric carbons involved in the linkage, while the presence of alternative minima that have relative energies less than 4 kcal/mol mostly requires equatorial bonds. However, molecules with two adjacent anomeric centers gave exceptions to these rules. Flexibility values related to a partition function show that the di‐axial trehalose analog is the most rigid. The di‐equatorial pseudodisaccharide analog with no anomeric centers is most flexible. Reproduction of these surfaces is proposed as a simple test of force fields for modeling carbohydrates. Also, these surfaces can be used in a simple hybrid method for calculating disaccharide energy surfaces. © 2000 John Wiley & Sons, Inc. * J Comput Chem 22: 65–78, 2001     

High resolution 1H NMR structural studies of sucrose octaacetate in supercritical carbon dioxide

High pressure (HP), high resolution (HR), proton nuclear magnetic resonance (1H NMR) spectroscopy has been utilized for the first time to investigate the solution structure of a carbohydrate based system, sucrose octaacetate (SOA), in supercritical CO2. The studies indicate that the average solution state conformation of the alpha-D-Glucopyranosyl ring of SOA in scCO2 medium is consistent with the 4C1 chair form, while the beta-D-fructofuranosyl ring adopts an envelope conformation. The investigations also suggest that scCO2 is a promising medium to study the solution structure and conformation of acetylated sugar systems. Spectral manifestations of a specific interaction between the acetate methyl protons and CO2 molecules are also presented.     

甘氨酸在葡萄糖-水和蔗糖-水混合溶剂中的体积性质

利用精密数字密度计测定了甘氨酸与不同组成葡萄糖-水、蔗糖、水混合溶剂 构成的三元系溶液的密度,计算了甘氨酸的表观摩尔体积、极限偏摩尔体积和理论 水化数,根据结构水合作用模型讨论了迁移偏摩尔体积的变化规律,并与乙二醇- 水和丙三醇-水等多羟基体系作了比较。结果表明,甘氨酸分子在多羟基化合物-水 体系中增体积效应的大小与多羟基化合物所含OH基数的多少有关。     

高效液相色谱法测定木奈果中的山梨醇和糖类

用高效液相色谱外标法测定了木奈果中的可溶性糖和山梨醇 ,采用 μ Spherogelcarbohydrate柱和示差折光检测器 ,以水为流动相 ,柱温 85℃。相关系数在 0 970 9以上 ,加标回收率为 75 0 0 %～ 88 37%。测定结果表明 ,可溶性糖在果肉中的累积依果肉不同的生长发育阶段有特征性的变化。