乳酸菌胞外多糖结构解析的研究方法

乳酸菌胞外多糖具有免疫调节和抗肿瘤、改善食品质地和口感等多种独特的功能特性,其分子结构多样性是影响功能的主要因素之一。乳酸菌胞外多糖的结构解析是研究其功能性和构效关系的前提和基础。本文根据乳酸菌胞外多糖结构解析过程中的关键步骤,总结了乳酸菌胞外多糖的分离纯化、初级结构及高级结构解析技术方法的研究进展,讨论了化学分析、仪器分析以及计算机辅助技术等多元技术方法在乳酸菌胞外多糖结构解析领域的综合运用,并对乳酸菌胞外多糖的结构研究的发展前景进行了展望。     

海藻多糖的组成及结构光谱分析

海藻多糖具有抗凝血等多种生物活性,其活性与多糖的组成结构有关。本文对近年来红藻、褐藻及少量绿藻多糖的单糖组成及含量研究以及FT-IR和12^C NMR两种主要光谱手段对多糖结构研究的结果进行了介绍。     

多糖类免疫调节剂的研究和应用

本文综述了从自然界分离出来的多糖的研究进展、存在问题和应用前景。讨论了多糖的免疫调节特性和作用、多糖的结构与功能以及它们的应用。     

白芷多糖的分析

研究了白芷多糖的结构和单糖组成。采用紫外光谱和红外光谱法对白芷多糖进行定性分析。结果表明,白芷多糖具有多糖特征性的紫外和红外吸收峰,其分子中存在酰胺结构;凝胶渗透色谱法测定结果表明,白芷多糖的峰值分子量为88538;采用气相色谱法测定白芷多糖中单糖的种类和构成比例,结果表明,白芷多糖由鼠李糖、阿拉伯糖、木糖、甘露糖、葡萄糖和半乳糖等7种单糖组成,并计算出其中6种单糖的摩尔组成比例。     

多糖化学合成研究进展

多糖是一类结构复杂的生物大分子,广泛分布于微生物、植物、动物等生物体中,参与众多重要的生命过程.然而,多糖研究一直受限于难以获得足量结构均一的多糖物质,这使得多糖的结构和功能研究及其相关的应用研究进展缓慢.近几十年来,随着糖合成技术的进步,糖的化学合成效率不断提高,人们开始关注复杂多糖的化学合成,并取得了一些进展.本文主要对多糖化学合成所涉及的糖基化方法、糖组装策略和代表性的合成工作进行综述,并对研究前景进行展望.     

甘草多糖螺旋结构的原子力显微镜研究

用原子力显微镜(AFM)对甘草多糖的微观结构进行观察, 实验结果表明, 甘草多糖主要由葡萄糖、阿拉伯糖和半乳糖组成. 甘草多糖分子的稀溶液铺展在Ni^2＋处理的云母片上, 经干燥, 乙醇固定后, 获得稳定、重复的图像. 甘草多糖分子具有高度分枝的结构, 并且糖链间形成环状、柱状或近似于螺旋状的结构. 甘草多糖链呈多股紧密的螺旋结构, 这种现象可能与该多糖中分子间的Van der Waals相互作用以及糖链间氢键缔合有关.     

一株抗氧化活性酵母菌产多糖的纯化与结构分析

研究了Pichia fermentans酵母菌产多糖YP5的单糖组成和结构。将酵母菌进行超声破碎后,采用乙醇沉淀法得到粗多糖,然后进行DEAE-纤维素色谱柱分离,得到均一的水溶性多糖YP5。经气相色谱分析表明,糖基由鼠李糖、阿拉伯糖、木糖、甘露糖、葡萄糖与半乳糖组成,其摩尔比为9.51∶1.33∶2.31∶0.94∶84.93∶0.96。乌氏粘度计法测得多糖的分子量为8.3×104。结合红外光谱和核磁共振1HNMR分析表明,该多糖YP5具有多糖特征性的红外吸收峰,存在酰胺结构,主要由β-D-葡聚糖组成。     

富硒金针菇子实体中硒多糖的分离纯化技术及红外光谱研究

对富硒金针菇子实体中硒多糖(Se-containing polysaccharide,Se-P)的分离、纯化进行了优化研究,并采用苯酚-硫酸法、ICP-MS法对硒多糖中多糖及硒含量进行了测定.确定硒多糖的最佳提取条件为:浸提温度80℃、浸提时间3 h、料液比1:50、提取3次合并滤液;其中多糖含量为12.48%,硒含量为7.97μg/g.将粗多糖经Sephadex G-100柱层析系统分离纯化,所得精硒多糖进行红外光谱分析表明:可溶性硒多糖均为糖苷键连接的吡喃多糖,其中水溶性硒多糖与普通多糖结构相似,而碱溶性硒多糖中由于硒酸酯的形成改变了原有多糖的吡喃环糖苷键的构型,进一步证明在金针菇的富硒培养过程中,硒参与了硒多糖的合成.     

气相色谱在多糖结构测定中的应用

综述了适用气相色谱分析的多糖的降解方法、衍生物的制备、固定液的选择以及气相色谱在多糖结构测定中的应用和最新进展。     

碳-13核磁共振法研究小皮伞多糖结构

采用＾１３Ｃ核磁共振法测定和确定了小皮伞多糖中的大分子葡聚糖,葡甘聚糖等３种多糖的一级结构,这些结果与组成分析和甲基化分析结果是一致的,确定了毫克级直接用＾１３Ｃ核磁共振法分析和检测多糖结构的方法。     

The Use of Megamolecular Polysaccharide Sacran in Food and Biomedical Applications

Natural polymer is a frequently used polymer in various food applications and pharmaceutical formulations due to its benefits and its biocompatibility compared to synthetic polymers. One of the natural polymer groups (i.e., polysaccharide) does not only function as an additive in pharmaceutical preparations, but also as an active ingredient with pharmacological effects. In addition, several natural polymers offer potential distinct applications in gene delivery and genetic engineering. However, some of these polymers have drawbacks, such as their lack of water retention and elasticity. Sacran, one of the high-molecular-weight natural polysaccharides (megamolecular polysaccharides) derived from Aphanothece sacrum (A. sacrum), has good water retention and elasticity. Historically, sacran has been used as a dietary food. Moreover, sacran can be applied in biomedical fields as an active material, excipient, and genetic engineering material. This article discusses the characteristics, extraction, isolation procedures, and the use of sacran in food and biomedical applications.     

Isolation,Characterization, and Medicinal Potential of Polysaccharides of Morchella esculenta

Mushroom polysaccharides are active medicinal compounds that possess immune-modulatory and anticancer properties. Currently, the mushroom polysaccharides krestin, lentinan, and polysaccharopeptides are used as anticancer drugs. They are an unexplored source of natural products with huge potential in both the medicinal and nutraceutical industries. The northern parts of Pakistan have a rich biodiversity of mushrooms that grow during different seasons of the year. Here we selected an edible Morchella esculenta (true morels) of the Ascomycota group for polysaccharide isolation and characterization. Polysaccharopeptides and polysaccharides from this mushroom were isolated using the green chemistry, hot water treatment method. Fourier transform infrared spectroscopy revealed the sugar nature and possible beta-glucan type structure of these polysaccharides. Antioxidant assays showed that the deproteinized polysaccharides have moderate free radical scavenging activity. These isolated polysaccharides exhibited good acetylcholinesterase (AChE) and butyryl cholinesterase (BChE) inhibition activities. Therefore, these polysaccharides may be valuable for the treatment of Alzheimer’s and Parkinson’s diseases. Further bioassays are needed to discover the true potential of M. esculenta polysaccharides for medicinal purposes.     

Anti-herpes activity of polysaccharide fractions from Stevia rebaudiana leaves

Abstract

The antiviral potential of natural polysaccharide compounds has been demonstrated, especially against enveloped viruses and members of the Herpesviridae family. Two polysaccharide fractions obtained from Stevia rebaudiana (Bertoni) leaves, that were active against Herpes simplex virus type 1 (HSV-1) were studied to investigate their mode of action. Both polysaccharides - SFW (crude faction) and SSFK (homogeneous alkaline fraction) - exerted antiviral effects on the initial stages of HSV-1 infection by inhibiting viral adsorption and penetration. When added after virus internalization, both fractions decreased plaque size. The effect of the fractions was confirmed by investigating viral glycoprotein expression. Based on the mode of action of the polysaccharides demonstrated in the present work and on their selectivity index, the polysaccharides obtained from S. rebaudiana could be an alternative treatment of infections caused by HSV-1.     

Comparison and characterization of polysaccharides from natural and cultured <Emphasis Type="Italic">Cordyceps</Emphasis> using saccharide mapping

Comparison and characterization of polysaccharides from natural and cultured Cordyceps on the basis of their chemical characteristics such as glycosidic linkages were performed for the first time using saccharide mapping. The results showed that polysaccharides from most of the natural and cultured Cordyceps had similar responses to enzymatic digestion. These polysaccharides mainly contained (1→4)-β-D-glucosidic linkages, and (1→4)-α-glucosidic, (1→6)-α-glucosidic, 1,4-β-D-mannosidic, as well as (1→4)-α-D-galactosiduronic linkages also existed in some polysaccharides. Especially, natural and cultured Cordyceps polysaccharides could be discriminated on the basis of high performance liquid chromatography profiles of pectinase hydrolysates, which is helpful to control the quality of polysaccharides from Cordyceps.     

Anti-diabetic Effects of Polysaccharides from Ethanol-insoluble Residue of Schisandra chinensis(Turcz.) Baill on Alloxan-induced Diabetic Mice

The ethanol-insoluble residue of Schisandra generated during lignans industrial production is usually treated as solid waste. However, there is active polysaccharide which could be used in it. In this work, the water-soluble polysaccharides from the ethanol-insoluble residue of Schisandra(ESCP) were obtained and their anti-diabetic effect was evaluated. The results indicate that ESCP could significantly reduce the blood glucose level in alloxan-induced diabetic mice. Moreover, the ESCP could significantly improve the lipid metabolism and increase the content of liver glycogen in alloxan-induced diabetic mice. The results indicate that ESCP could be developed into a potential natural hypoglycemic agent.     

Synthesis and luminescent properties of water-soluble nanobiocomposite CdSe/polysaccharide quantum dots

Water-soluble nanobiocomposite CdSe quantum dots were obtained using the stabilizing potential of natural biologically active polysaccharides galactomannan and κ-carrageenan. A complex of physicochemical methods was used to investigate the biphasic amorphous-crystalline structure of the obtained nanocomposites, the size range (4.8—6.9 nm) of the formed CdSe particles was determined, and, additionally, it was shown that aqueous solutions of the nanocomposites in question were characterized by the presence of photoluminescence in two spectral regions, namely, 410—450 and 510—580 nm.     

Biological functions of synthetic polysaccharides

Structurally well-defined polysaccharide derivatives have been synthesized via ring-opening polymerization of bicyclic anhydro sugar derivatives and via enzyme-catalyzed polymerization using phosphorylase. This article describes the following four synthetic polysaccharides, (a) Octadecylated amphiphilic polysaccharides, (b) Regiospecifically fluorinated polysaccharide, (c) Comb-shaped branched polysaccharide, (d) Graft copolymers having pendant polysaccharide chains. None of these polysaccharides could be prepared by direct chemical modifications of natural polysaccharides. The synthetic polysaccharides are useful as tools to elucidate structure-function relationships and exhibit various novel biofunctional properties.     

Application of chromatography in purification and structural analysis of natural polysaccharides: A review

Polysaccharides are widely distributed in natural sources from monocytic microorganisms to higher animals, and are found in a variety of biological activities in recent decades. Natural polysaccharides have the characteristics of large molecular weight, diverse composition, and complex structure, so their purification and structural analysis are difficult issues in research. Chromatography as a powerful separation technique, plays an irreplaceable role in the separation and structural analysis of natural polysaccharides, especially in the purification of polysaccharides, the separation of hydrolysates, and the analysis of monosaccharide composition. The separation mechanisms and application of different chromatographic methods in the studies of polysaccharides were summarized in this review. Moreover, the advantages and drawbacks of various chromatography methods were discussed as well.     

Protein-Polysaccharide Interactions for Stabilization of Food Emulsions

Proteins, polysaccharides and their blends, as examples of natural biopolymers, are surface active materials. Biopolymers may be considered as amphiphilic macromolecules that play an essential role in stabilizing food formulations (foams, emulsions and dispersions). Under specific conditions (such as protein-to-polysaccharide ratio, pH, ionic strength, temperature, mixing processing), it has been stated that proteins and polysaccharides form hybrids (complexes) with enhanced functional properties in comparison to the proteins and polysaccharides alone. Different protein-polysaccharide pairs are reviewed with particular attention to the emulsification capability of their mixtures. In the case of uncomplexed blends of biopolymers, competitive adsorption onto hydrophobic surfaces is generally reported. Conversely, electrostatic complexation between oppositely charged proteins and polysaccharides allows better anchoring of the new-formed macro-molecular amphiphile onto oil-water interfaces. Moreover, improved thermal stability and increased resistance to external treatment (high pressure) involved in food processing are obtained. This review presents basic and applied knowledge on protein-polysaccharide interactions in aqueous medium and at the oil-water interface in food emulsion systems. Electrostatic interactions and thermodynamic incompatibility in mixed biopolymer solutions are correlated to the functional properties (rheology, surface hydrophobiciry, emulsification power) of these interesting blends. Basic and industrial selected systems of different families of hydrocolloids (as gum Arabic, galactomannans, pectins) and protein (caseins, whey, soya, gelatin) mixtures are reviewed.     

Isolation and characterization of antigens fromPseudomonas aeruginosa in exhaustively cultivated biomass

Biotechnology for producing biomass and controlling biosynthetic processes of desired complex polysaccharides is developed. The isolated polysaccharides exhibit protective activity in a test for active protection. Various polysaccharide fractions induced the production of antibodies with different degrees of passive protection. The most active antibodies are obtained from the blood of animals immunized with the first fraction of polysaccharides from biomass strain 263. Polysaccharides of the first fraction are analyzed by HPLC. The amount of nucleic acids and proteins in the preparation is quantitatively estimated. Presented at the Third International Symposium on Natural Product Chemistry, Bukhara, 1998. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 658–660, September–October, 1999.