Structure of an Extracellular Polysaccharide from a Strain of Lactic Acid Bacteria

A new extracellular polysaccharide (EPS-I) isolated and purified from Z222, a strain of Lactic acid bacteria has been investigated. Sugar composition analysis, methylation analysis and ^1H NMR and ^13C NMR spectroscopy reveal that the EPS-I is composed of a pentasaccharide repeating unit. The sequence of sugar residue was determined by using two-dlmensional NMR spectroscopy, including heteronudear multiple-bond correlation(HMBC) and nuclear overhauser effect spectroscopy (NOESY).     

壳聚糖基载药纳米微粒制备研究进展

有关可生物降解多糖类纳米微粒用作给药载体的研究，近年颇受重视。简要评述了壳聚糖基载药纳米微粒的制备方法，包括共价交联、离子诱导、沉淀析出、大分子复合和自组装方法及其研究进展。     

生漆多糖的分离与结构研究

生漆用丙酮提取不溶解物，除去其水不溶部分、依次进行７３２阳离子交换树脂和ＳｅｐｈａｄｅｘＧ－１００柱层析、得到白色粉末漆多糖．分子量１２．５×１０￣４．其组成为Ｄ－半乳糖、Ｄ－葡萄糖醛酸、Ｌ－阿拉伯糖和Ｌ－鼠李糖．摩尔比为７．７：１．８：０．４：０．１．经羧基还原、甲基化反应、高碘酸盐氧化、Ｓｍｉｔｈ降解和ＧＣ－ＭＳ、ＩＲ、￣１Ｈ－ＮＭＲ、￣１３Ｃ－ＮＭＲ分析、结果表明，漆多糖为多分支结构、分子主链由β（１→３）Ｄ－半乳糖基构成．部分半乳糖基Ｃ＿６位有支链，另有部分半乳糖基以（１→６）键连接，其中β（１→３）与β（１→６）甙键糖基组成比为１．８３：１．分子的支链由葡萄糖醛酸基、阿拉伯糖基、鼠李糖基组成，并且葡萄糖醛酸基构成分子的末端基．     

Rheological and DSC study of sol-gel transition in aqueous dispersions of industrially important polymers and colloids

 Gelation kinetics, mechanical spectra, thermal scanning rheology (TSR), and differential scanning calorimetry (DSC) in aqueous solutions of gelling polymers and colloids such as seaweed polysaccharides (agarose, carrageenans), microbial polysaccharides (gellan, curdlan), plant polysaccharides (methylcellulose), globular proteins (casein, glycinin, β-conglycinin), fibrous proteins (gelatin, fibrin), and polyvinyl alcohol, which are related to foods, cosmetics, biomedical and pharmaceutical applications, are described. Some gelation processes at a constant temperature have been treated successfully by an equation of first order kinetics or by other modified equations, and the molecular mechanism of gel formation is discussed briefly. For water-soluble polymers, the criterion of the gel or sol based on the frequency dependence of storage and loss moduli gives valuable informations. TSR and DSC are complementary, and the combination of these methods has been proved to be useful. Received: 17 June 1997 Accepted: 28 August 1997     

动态膜渗透压法测定生漆多糖水溶液

<正> 生漆是一种性能优异的超耐久涂料,其主要成份为漆酚、漆酶、糖蛋白、多糖和水。多糖由D-半乳糖(65％),4-O-甲基-D-葡萄糖醛酸(24％),D-葡萄糖醛酸(3％),L-阿拉伯糖(4％)和鼠李糖(3％)组成。它带大量支链,在侧链上有大约1/4mol羧基从而显示聚电解质溶液性质。     

Conformations of polysaccharides in solution,gels, and crystals

Solution-gel-crystal phase transitions in a polysaccharide-water-salt system were examined. Polysaccharide helices were shown to exhibit identical conformation in solutions, gels, and crystals containing up to 50 % of water.Translated fromIzvestiya Akademii Nauk. Seriya Khitnicheskaya, No. 6, pp. 1543–1546, June, 1996.     

小刺猴头菌子实体水溶性多糖HP Ⅱ的结构研究

小刺猴头菌子实体多糖经乙醇分级和Sepharose CL-6B柱层析，得到多糖HPⅡ．经Sephadex G-100柱层析，高压玻璃纤维纸电泳，比旋光度测定等方法鉴定：HPⅡ在相对分子质量大小和极性上都较为均一．经部分酸水解、高碘酸氧化、Smith降解、IR分析、甲基化分析、GC和GC／MS联机分析等方法，确定了其结构：（1→6）Glc构成主链的核心结构，在3-O处有分枝，平均每7个己糖残基有3个分枝残基；A，B为侧链结构，其构成成分为Glc和Gal；末端残基为（1→）Glc．     

香菇多糖核心片段六糖的合成研究

以已知的2,3,4,6-四-O-苯甲酰基--D-葡萄吡喃糖-(13)-[2,3,4,6-四-O-苯甲酰基-β-D-葡萄吡喃糖-(16)]-2,4- 二-O-乙酰基-β-D-葡萄吡喃糖-(13)-2,4,6-三-O-乙酰基-α-D-葡萄吡喃糖三氯乙酰亚胺酯(2)为供体, 以2-O-苯甲酰 基-4,6-O-苄叉基-α-D-葡萄吡喃糖烯丙基苷(4)作为受体, 立体专一性地偶联得到β-1,3连接的五糖5. 五糖5酸解脱去4,6-苯亚甲基基后与2,3,4,6-四-O-苯甲酰基-α-D-葡萄吡喃糖三氯乙酰亚胺酯(7)偶联, 区域和立体专一性地得到全保护的β-1,3主链β-1,6支链的六糖8. 六糖8脱保护后得到目标化合物香菇多糖核心片段六糖9. 发展了合成该类化合物的一种新方法.     

温和条件下柱前标记-高效液相色谱-质谱法测定枸杞多糖中单糖组成

基于高效液相色谱-质谱联用分析技术（HPLC-MS）,在温和的NH₃·H₂O条件下,采用1-苯基-3-甲基-5-吡唑啉酮（PMP）衍生化试剂成功地标记了果糖及多种醛单糖,同时提出了PMP标记果糖的衍生化机理。采用Kromasil-C18色谱柱（100 mm×4.6 mm,3.5 μm）分离,梯度洗脱,选择离子模式检测,建立了8种常见单糖标记物的结构确认及含量测定的分析方法。该方法在一定质量浓度范围内具有良好的线性（相关系数> 0.9947）,检出限为0.003~0.05 mg/L,定量限为0.01~0.15 mg/L。平均回收率为65.1%~116.2%,相对标准偏差≤10.2%（n=5）。自制4个产地枸杞多糖,对其单糖组成的分析结果表明,它们均由甘露糖、果糖、鼠李糖、半乳糖、葡萄糖、木糖、阿拉伯糖和脱氧核糖8种单糖组成,但各种单糖含量的分布有较大的差异。该法简便,灵敏度高,重复性好,可用于水热法水解枸杞多糖水解液中单糖标记物结构的确认及测定,对规范植物多糖的质量控制具有重要意义。     

Optimization Extraction and Antioxidant Activity of Crude Polysaccharide from Chestnut Mushroom (Agrocybe aegerita) by Accelerated Solvent Extraction Combined with Response Surface Methodology (ASE-RSM)

The present work is conducted to investigate the optimal extraction technology of polysaccharide from chestnut mushroom (Agrocybe aegerita) using a new method based on accelerated solvent extraction combined with response surface methodology (ASE-RSM). The conventional reflux extraction (CRE) method and ultrasonic-assisted extraction (UAE) method were also carried out. Additionally, the in vitro antioxidant activities, including ABTS and DPPH assay, were evaluated. The RSM method, based on a three level and three variable Box–Behnken design (BBD), was developed to obtain the optimal combination of extraction conditions. In brief, the polysaccharide was optimally extracted with water as extraction solvent, extraction temperature of 71 °C, extraction time of 6.5 min, number of cycles of 3, and extraction pressure of 10 MPa. The 3D response surface plot and the contour plot derived from the mathematical models were applied to determine the optimal conditions. Under the above conditions, the experimental value of polysaccharide yield was 19.77 ± 0.12%, which is in close agreement with the value (19.81%) predicted by the model. These findings demonstrate that ASE-RSM produce much higher polysaccharide and consumed environmentally friendly extraction and solvent systems, have less extraction discrimination and shorter time and provide scientific basis for industrialization of polysaccharide extraction. Moreover, it was proved that the polysaccharide had the potential ability to scavenge ABTS and DPPH.