Biosynthesis,purification and structure-property relationships of new cyanobacterial exopolysaccharides

Exopolysaccharides are considered as omnipresent and abundant bioproducts. However, the diversity of cyanobacteria offers a great opportunity for discovering new bioproducts as they are not properly explored. The current work targeted to characterize an indigenous cyanobacterial strain CCC-746 isolated from Bishnupur, India for production of exo-polysaccharides. The molecular and microscopic observation stated that the isolated cyanobacteria is Anabaena sp. The analysis of biomass composition showed carbohydrates, protein, lipid, ash and moisture content are 32.10%, 36.56%, 24.13%, 5.89% and 1.32% (w/w) respectively. The maximum production of EPS was 340.70 mg/L, when grown in 10 mM CaCl₂ supplemented BG11 medium. The capsular polysaccharide and released exo-polysaccharide were purified by gel filtration chromatography, and molecular weight was found as 12.52 and 9.2 kDa, respectively. The major component of both exo-polysaccharides was carbohydrate with glucose, xylose and glucuronic acid as major monosaccharides. Capsular polysaccharide and released exo-polysaccharide were composed of [→4)-Glcp-(1→] backbone. Both exo-polysaccharide were found negative in charge and showed remarkable antioxidant and scavenging activities. Capsular polysaccharide and released exo-polysaccharide solubilized in aqueous solution exhibited the behaviour of pseudo-plastic fluids.     

碳纤维微电极负载金纳米粒子用于芦荟多糖的在体动态监测

建立了一种对活体芦荟储水凝胶组织中芦荟多糖进行在体实时动态检测的电化学方法. 通过在活体芦荟植株凝胶中嵌入高灵敏度的纳米金粒子修饰的碳纤维微电极, 对不同光照条件下芦荟植株中的芦荟多糖进行在体动态监测, 进而评价植株应激外界环境下芦荟多糖含量的实时变化. 实验结果表明, 纳米金粒子修饰的碳纤维微电极对芦荟储水凝胶组织中芦荟多糖具有显著的电催化活性, 不同光照环境下生长的芦荟植株中芦荟多糖含量的动态变化具有显著的统计学差异. 该修饰电极可用于芦荟植株中芦荟多糖动态变化的在体实时监测, 使电化学检测方法有望成为监测植物光合作用程度的一种快捷检测手段.     

黄原胶与魔芋胶协同相互作用及其凝胶化的研究

黄原胶和魔芋胶都是非凝胶多糖，但将二者按一定比例混合可以出现协同相互作用，得到凝胶．当黄原胶与魔芋胶的比例为７０／３０（ｍ／ｍ），总糖浓度为１．０％时协同效应达到最大值．混合多糖胶凝化能力不仅与混合比例有关，还与黄原胶的转变温度和体系盐离子浓度有关．     

淀粉及纤维素三(3-三氟甲基苯基氨基甲酸酯)手性固定相的制备及其性能评价

为了扩展多糖类手性固定相的种类,制备了基于淀粉及纤维素三(3-三氟甲基苯基氨基甲酸酯)的涂敷型手性固定相,以正己烷-异丙醇混合液为流动相,对8种手性化合物进行了高效液相色谱拆分。研究表明: 虽然与应用最广泛的分别以淀粉及纤维素三(3,5-二甲基苯基氨基甲酸酯)为手性选择因子的商品化手性柱Chiralpak AD和Chiralcel OD相比,所制备的手性固定相的手性分离能力较低,但纤维素三(3-三氟甲基苯基氨基甲酸酯)手性固定相显示出特异的手性识别能力,一些手性化合物在此固定相上得到了比在Chiracel OD上更好的分离;所制备的手性固定相的手性识别能力随流动相中异丙醇含量的降低而变好,当流动相中正己烷与异丙醇的体积比为95:5时所制备的手性固定相显示出相对较高的手性识别能力;总体来说,淀粉三(3-三氟甲基苯基氨基甲酸酯)手性固定相的手性识别能力稍强于纤维素三(3-三氟甲基苯基氨基甲酸酯)手性固定相,同时两种手性固定相的手性识别能力具有一定的互补性。     

Cactus polysaccharides enhance preservative effects of ultrasound treatment on fresh-cut potatoes

The shelf life of fresh-cut fruits and vegetables is affected by microbial growth, enzymatic browning, and loss of flavor. Although ultrasound (US) treatment is often used in the preservation of fresh-cut fruits and vegetables, it has limited antibacterial and preservative effects. Here, we used cactus polysaccharides (CP) to enhance the preservative effect of ultrasound treatment and extended the shelf life of fresh-cut potatoes. The results showed that combined treatment (CP + US) exerted better antimicrobial and anti-browning effects than individual treatments (either US or CP alone). In addition, CP + US has no adverse effect on texture and quality properties, as well as reduced the mobility of internal water. Combination treatment not only significantly decreased the activities of polyphenol oxidase and peroxidase (P < 0.05), but also maintained a high level of phenylalanine ammonia lyase activity and total phenol content during storage. It also maintained the integrity of cell membrane and reduced its permeability by inhibiting the peroxidation of membrane lipids. In addition, CP + US treatment significantly inhibited the activity of antioxidant enzymes and maintained a high DPPH scavenging ability. GC-IMS technology was used to evaluate the flavor of fresh-cut potatoes. The results showed that CP + US treatment reduced the production of a peculiar smell during storage and maintained a good flavor by inhibiting the production of aldehydes. Taken together, these results indicate that the effective preservation method of CP + US treatment can be utilized to increase the shelf life of fresh-cut potatoes.     

Structural analysis and anticomplement activity of a novel homogenous polysaccharide isolated from Juniperus tibetica kom

Abstract

Juniperus tibetica Kom., a common forest species in Tibet, has been traditionally used in Tibetan medicine to treat rheumatic arthritis. In order to investigate the effective substances of J. tibetuca, anticomplent assay-guided fractionation using gradient anion-exchange chromatography and gel permeation chromatography was applied to the crude polysaccharides of the twigs and leaves of J. tibetica and led to the isolation of a homogenous polysaccharide, YB-PS. It exhibited a robust anticomplement activity (CH₅₀: 461?±?10?μg/mL) through the classical pathway of complement system activation by targeting complement components C1q, C3, C4 and C5. The structure of YB-PS was studied by monosaccharide composition and methylation analyses, 1?D, 2?D NMR data and scanning electron microscope. The results indicated that YB-PS was composed of Ara, Gal, and Glc with a molar ratio of 5.8:3.0:1.2. Its backbone was comprised of 1,3-linked α-Araf, 1,3,5-linked α-Araf, 1,2,4-linked α-Galp, and 1,3-linked α-Glcp with terminal α-Araf, β-Galp and 1,4-linked β-Galp as branches. YB-PS was found to have a sheet structure with smooth surface. This study provided scientific foundation for YB-PS as a potential complement inhibitor to treat diseases involved with excessive activation of the complement system.     

Direct Synthesis of Biodegradable Polysaccharide Derivative Hydrogels Through Aqueous Diels‐Alder Chemistry

A robust synthetic strategy where polysaccharide derivative precursors react through aqueous Diels–Alder chemistry without the involvement of catalysts and coupling reagents, allowing for the direct encapsulation of positive and negative proteins within biodegradable hydrogels. The results demonstrated that the aqueous Diels–Alder chemistry provides an extremely selective reaction and proceeds with high efficiency for polysaccharide bioconjugation. This synthetic approach uniquely allows for the direct fabrication of biologically functionalized gels with ideal structures, which provides a competitive alternative to conventional conjugation techniques such as click chemistry.

     

Flocculation Properties of Some Cationic Polysaccharides

Flocculation of a clay suspension model using some cationic polysaccharides has been studied by turbidity measurements. The investigated polyelectrolytes contain quaternary ammonium salt groups, N-ethyl-N, N-dimethyl-2-hydroxypropylene ammonium chloride, attached to a dextran backbone. The flocculation efficiency was studied as a function of the polycation charge density and some flocculation parameters (polycation dose, settling time, concentration of both clay suspension and parent solution of polymer). All investigated cationic polysaccharides showed high flocculating efficiency at optimum flocculant doses, which correlated well with the charge density of the polycations: the higher charge density, the lower the amount of dextran derivative was required for reaching the maximum clarity degree (of about 100%). This finding is consistent with the neutralization mechanism for a flocculation process. The residual turbidity values also varied with the settling time and the concentrations of clay suspension and parent solution of polymer. Possible reasons for these dependences are discussed.     

Polysaccharide- and β-Cyclodextrin-Based Chiral Selectors for Enantiomer Resolution: Recent Developments and Applications

Polysaccharides, oligosaccharides, and their derivatives, particularly of amylose, cellulose, chitosan, and β-cyclodextrin, are well-known chiral selectors (CSs) of chiral stationary phases (CSPs) in chromatography, because they can separate a wide range of enantiomers. Typically, such CSPs are prepared by physically coating, or chemically immobilizing the polysaccharide and β-cyclodextrin derivatives onto inert silica gel carriers as chromatographic support. Over the past few years, new chiral selectors have been introduced, and progressive methods to prepare CSPs have been exploited. Also, chiral recognition mechanisms, which play a crucial role in the investigation of chiral separations, have been better elucidated. Further insights into the broad functional performance of commercially available chiral column materials and/or the respective newly developed chiral phase materials on enantiomeric separation (ES) have been gained. This review summarizes the recent developments in CSs, CSP preparation, chiral recognition mechanisms, and enantiomeric separation methods, based on polysaccharides and β-cyclodextrins as CSs, with a focus on the years 2019–2020 of this rapidly developing field.     

新疆金鸡菊多糖体外抗肿瘤活性的研究

采用Tetrazolium bromid(MTT)试验法和光学显微镜法,初步研究了金鸡菊多糖对肿瘤细胞增殖的抑制作用和对细胞形态及细胞凋亡的影响.结果表明:金鸡菊多糖对肝癌细胞BEL-7404、食道癌细胞Eca109和宫颈癌细胞HeLa增殖都有抑制作用,且随着药物(多糖)作用浓度和时间的增加,显示出较好的量效关系.通过Hoechst33258染色观察细胞形态,初步证明金鸡菊多糖能诱导HeLa细胞发生凋亡改变;倒置显微镜下观察发现经金鸡菊多糖处理的癌细胞数目有所减少,细胞较为分散,细胞间连接减少,产生圆缩脱落;乳酸脱氢酶LDH活力分析实验表明金鸡菊多糖诱导Hela细胞的凋亡要有适宜的浓度.