酵母甘露聚糖硫酸酯化前后结构与生物活性比较研究

对酵母甘露聚糖及硫酸酯化酵酯母甘露聚糖的相对分子质量、红外光谱、离子色谱、比旋光度、IO4^-氧化、SO4^2-含量、Smith降解、电泳及THP－1细胞分泌IL-la的水平等进行了测定，结果表明，硫酸酯化后相对分子质量增加，IR光谱[α]D^20均有明显变化，电泳迁移加快，IO4^-氧化甲酸生成量减少，硫酸酯化位置在非还原末端，C（3）对碱位置稳定，Smith降解结果表明硫酸化前后基本结构无明显变化。硫酸酯化前后样品对THP－1细胞分泌IL－1a水平影响差异显，对IL-6,IL-8,TNFa,IL-2亦有影响。     

鱿鱼墨多糖的硫酸酯化及抗凝血活性

本文采用三氧化硫吡啶复合物二甲亚砜法首次对北太平洋鱿鱼墨多糖SIP进行硫酸酯化。对硫酸酯化后多糖样品的基本化学组成进行测定,分析了糖组成,硫酸基含量和分子量。并结合红外光谱和一维核磁分析其结构,结果表明硫酸酯化主要发生在GalNAc的4,6位上。进一步的凝血活性分析表明有较好的延长APTT和PT时间效果。对凝血因子的抑制实验则表明,硫酸化后的鱿鱼墨多糖TBA-1对FIIa和FXa 均有显著的抑制作用。     

中酯化度果胶离子络合复合物凝胶对葡萄糖迁移的影响

通过控制中酯化度果胶多糖溶液pH、多价离子浓度以及对凝胶-溶胶温度曲线的测定,研究其凝胶敏感特性和可逆性能.利用中酯化度果胶多糖的凝胶特性,以体外模拟实验研究不同凝聚态多糖体系中葡萄糖的生成和迁移行为.结果表明:中酯化度果胶多糖具有酸敏感、多价离子敏感等凝胶特性,且其凝胶具有温度可逆性.在降低葡萄糖迁移速率和降低淀粉生成葡萄糖速率两方面,中酯化度果胶钙凝胶体系效果较其他体系明显,并且使生成葡萄糖呈均化释放.     

玉米芯碱提水溶性多糖及其硫酸酯抗病毒活性的研究

从玉米芯中,用2%NaOH提取,HCl中和,经乙醇醇析,制备碱提水溶性多糖.用氯磺酸吡啶法修饰制备多糖硫酸酯.离子色谱法测其硫酸根含量为11.23%.玉米芯多糖经硫酸化修饰后对柯萨奇病毒(Coxsackie B3Virus)有一定的抑制作用,但对人全血凝血时间无显著影响.     

正交试验法优选穿心莲内酯硫酸酯化反应工艺

硫酸酯化反应以分子结构中的羟基为反应位点,向有机分子中引入硫酸酯基,是一种有效改善天然产物水溶性的结构修饰途径[1]。有些药物因水溶性差,致使其在临床应用中存在一些问题,如生物利用度不高,服用量大,制成的片剂或胶囊体内吸收缓慢等。这类化合物经硫酸酯化后不但可以增加     

褐藻糖胶的分离、化学修饰和清除羟自由基作用研究

用酸法提取褐藻糖胶,经乙醇初步分级得褐藻糖胶HD1和褐藻淀粉HD2;褐藻糖胶HD1经DEAE(二乙氨乙基)-纤维素柱层析,控制洗脱速度1.0mL/min,先经二次水洗脱,然后用0～1.5mol/LNaCl梯度洗脱;浓缩、透析,得褐藻糖胶HDⅠ和HDⅡ;用氯磺酸法合成了硫酸酯化褐藻糖胶HDSⅡ;红外光谱法确定了硫酸酯键的特征吸收。通过Fenton反应产生羟自由基模型,对比研究了褐藻多糖化学修饰前后体外抗氧自由基性质;褐藻糖胶HDⅡ经硫酸化修饰后、通过清除.OH自由基表明,褐藻糖胶组分HDⅡ、HDSⅡ均可作为自由基清除剂。     

碳纳米管的化学修饰以及作为润滑油添加剂的摩擦学性能研究

采用硫酸和硝酸混合酸对催化裂解法(CVD法)制备的多壁碳纳米管(MWNNTs)进行纯化,然后运用硬脂酸对碳纳米管进行表面修饰,并研究了硬脂酸修饰后的碳纳米管的表面状况以及作为润滑油添加剂的摩擦学行为．实验结果表明,在硫酸催化剂作用下,通过酯化反应碳纳米管能够被硬脂酸包覆,并且硬脂酸修饰的碳纳米管作为润滑油添加剂能够显著提高基础油的减摩抗磨性能,当添加量为0．15％左右时,润滑油的减摩抗磨性能最佳,与基础油相比可以使摩擦系数下降10％左右,磨损量下降30％～60％．     

采用层层自组装与光化学修饰法在聚氨酯表面固定生物多糖衍生物

采用层层自组装技术与光化学修饰方法相结合在聚氨酯材料表面固定生物多糖衍生物,首先合成具有光反应活性的叠氮壳聚糖,再在聚氨酯基材表面进行叠氮壳聚糖与香菇多糖硫酸酯的层层自组装,然后通过光化学反应对自组装多层膜修饰层进行交联,制备得到生物多糖衍生物层层自组装与光化学表面修饰的聚氨酯材料.通过红外光谱、X射线光电子能谱、水接触角测量仪、抗菌活性测试、溶血试验和血小板黏附测试等方法对被修饰聚氨酯材料的表面性能和生物性能进行了分析,测试结果表明修饰后的聚氨酯材料表面的亲水性和血液相容性得到改善,并且被修饰材料对大肠杆菌具有良好的抑制效果.     

木薯淀粉硫酸酯的制备及理化性质

以NaHSO3和NaNO2为酯化剂,采用水相法制备了低取代度的淀粉硫酸酯(SSE),测定了SSE糊的冻融稳定性、凝沉性能、透明度、黏度;利用红外光谱仪分析了产物的化学结构.结果表明,酯化的SSE糊的透光率比淀粉的提高22.4％,透明度稳定性明显增强;SSE糊的黏度冷热差值均比淀粉的低,抗老化性能增强、凝沉性能得以改善,...     

旋光性聚{(+)-甲基丙烯酸-2,5-二[4′-((S)-2-甲基丁氧基)苯基]苄酯}的合成与表征

设计、合成了一个带有横挂三联苯侧基的手性乙烯基单体——(+)-甲基丙烯酸-2,5-二[4′-((S)-2-甲基丁氧基)苯基]苄酯,进行了普通自由基和原子转移自由基聚合反应.所得聚合物具有比单体低30°左右的比旋光度,且在侧基的紫外吸收处呈现明显不同于单体的Cotton效应,说明其主链可能形成了具有相反旋光方向的螺旋构象.在所研究范围内,聚合条件对聚合物的旋光度没有明显的影响.在分子量较小时,聚合物的比旋光度随着分子量的增加而降低,说明主链螺旋构象的贡献在增大,而当分子量达到一定值后,聚合物的比旋光度不再随分子量的增加而显著变化.     

Plant polysaccharides

IR spectroscopy has been used to detect a mannan inUngernia bulbs. The mannan was determined qualitatively and quantitatively directly in a preparation of ground bulbs, avoiding the process of extracting the polysaccharide.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 40 64 75. Translated from Khimiya Prirodynykh Soedinenii, No. 5, pp. 683–685, September–October, 1997.     

Interaction of dye and polysaccharides

Summary The interactions between amylose, amylodextrine and Benzopurpurine 4 B were studied by spectral and equilibrium dialyses methods. From the binding constant of amylose and amylodextrine, the molar changes in entropy and enthalpy for binding of the dye were calculated. BothH° andS° were positive. The positive value ofS° may be explained by the increase of flexibility of the polymer chain with increasing temperature.

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Zusammenfassung Die Wechselwirkung zwischen Amylose, Amylodextrin und Benzopurpurin 4 B wurde mit den Methoden der Spektroskopie und der Gleichgewichtsdialyse untersucht. Die molare Änderung von Entropie und Enthalpie wurde aus der Bindungskonstante berechnet. H° und S° sind beide positiv. Sie sind damit zu erklären, daß die Kettenbeweglichkeit der Polymeren mit der Temperatur zunimmt.

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The authors acknowledge the help of Dr.T. Kamata (The Government Chemical Industrial Research Institute, Tokyo) with the measurement of the molecular weight of the amylose.     

Bacterial antigenic polysaccharides

Conclusions Based on the data of selective cleavage, methylation, and oxidation with CrO₃ it was shown that the repeating unit of the polysaccharide chain of the liposaccharide from type 6Sh. dysenteriae is the trisaccharide-D-N-acetylgalactosaminyl-(1–3)--D-galactopyranosyl-(1–6)--D-glucopyranose, to the galactose residue of which is attached an unindentified acid component in the 4 position.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2302–2308, October, 1975.The authors express their gratitude to G. V. Vikha for graciously supplying the-hexosaminidase and to B. M. Zolotarev for taking the mass spectra.     

Plant polysaccharides. IX. Isolation and anticoagulant activity of the polysaccharides ofLagochilus usunachmaticus

A polysaccharide possessing pronounced direct-action anticoagulant activity has been isolated from the epigeal part ofLagochilus usunachmaticus.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 40 64 75. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 690–692, September–October, 1997.     

Architecture of polysaccharides with specific structures: synthesis of hyperbranched polysaccharides

An oxazoline sugar monomer 1 having two hydroxy groups was employed as an AB₂ type monomer for the synthesis of a hyperbranched aminopolysaccharide 2. The polymerization of 1 was carried out in the presence of an acid catalyst. The unit structure of product polysaccharide was determined to be β‐glucopyranan. The degree of branching was estimated by calculation of the content of the terminal units in the total units after the reaction of the polymerization product with 1,3‐dichloro‐1,1,3,3‐tetraisopropyldisiloxane. The molecular weight determined by the light‐scattering method was higher than that estimated by gel permeation chromatography. The detosylation of 2 took place under the alkaline conditions, giving rise to a free hyperbranched aminopolysaccharide. Copyright © 2000 John Wiley & Sons, Ltd.     

Viscosity of aqueous solutions of polysaccharides and hydrophobically modified polysaccharides: Application of Fedors equation

Amphiphilic polysaccharides have been obtained by hydrophobic modification of a neutral bacterial polysaccharide, dextran. Various amounts and types of aliphatic hydrocarbon groups have been attached to dextran.The solution behaviour of unmodified dextran samples and amphiphilic dextran derivatives is characterized by viscometric measurements. The overall viscosity behaviour of unmodified polysaccharides is described up to C × [η] = 3, using the equation of Fedors [Fedors RF. Polymer 1979;20:225] which involves only a concentration parameter. The latter is shown to depend on the hydrodynamic volume of the macromolecules in solution.The equation of Fedors is shown to conveniently estimate the viscosity behaviour of amphiphilic dextran derivatives up to C × [η] = 1. The interdependence between Fedors parameter and other viscometric characteristics (intrinsic viscosity, Huggins coefficient) is evidenced. These results are extended to the data of other authors.