细茎石斛多糖的降血糖活性作用

观察细茎石斛 ( Dendrobium moniliforme ( L .) Sw .)多糖对多种模型小鼠血糖水平的影响 ,探讨其降血糖作 用机理 .采用昆明种小鼠分组 ,分别以细茎石斛多糖 (100 mg· kg - 1 、200 mg· kg - 1 )、格列苯脲片 (50 mg· kg - 1 )、盐 酸苯乙双胍 (50 mg· kg - 1 )或生理盐水灌胃 ,测定各正常小鼠、肾上腺素性糖尿病和四氧嘧啶性糖尿病小鼠的血糖 水平 .结果 100 mg · kg - 1 、200 mg · kg - 1 两个剂量的细茎石斛多糖均能显著降低肾上腺素、四氧嘧啶引起的糖尿病 小鼠的血糖水平 (p < 0. 01) ,提高四氧嘧啶性糖尿病小鼠的葡萄糖耐量 (p < 0. 01),但对正常小鼠的血糖水平无影 响 .细茎石斛多糖具有明显的降血糖作用 ,是一种值得开发利用的降糖植物多糖.     

Solution properties of exocellular polysaccharides of rhizobium leguminosarum. Static and dynamic light-scattering: Characterization in dilute solution

Three polysaccharides, Rhizobium leguminosarum 8002 EPS(I), Rhizobium trifolii TA1-EPS (II), Rhizobium leguminosarum 127K87 EPS (III), produced by bacteria of Rhizobium genus have been investigated by static and dynamic light scattering combined with chirooptical measurements. All three polymers have the same backbone but differ in the length of the side chains and in the content of minor substituents. An isothermal conformational transition coil → helix was observed with I and II by adding salt (NaCl). The molecular parameters of the polysaccharides in the ordered state were determined by light-scattering data. Increasing the ionic strength a shrinking of the helix was observed accompanied by a corresponding decrease in the radius of gyration. An extraordinary chain stiffness in terms of Kuhn segment lengths was found in both cases, similar to that already observed for other microbial polysaccharides. In the case of III no disorder → order transition was induced by the salt, and the scattering behavior corresponds to that of a rather flexible polymer with a characteristic ratio C_∞ = 24. The incapability of III to form a helical structure is attributed to the effect of the very long side chain. The analysis of the time correlation functions revealed typical flexible chain behavior for all three polysaccharides. This behavior for the two ordered polymers is in agreement with a recent theory by Maggs and is due to bending modes of the rods. ©1995 John Wiley & Sons, Inc.     

Determination of the compositions of polysaccharides from Chinese herbs by capillary zone electrophoresis with amperometric detection

In this paper, capillary zone electrophoresis with amperometric detection (CZE-AD) was applied to determine the compositions of hetero-polysaccharides from Chinese herbs, Angelica sinensis and flax by analyzing their hydrolyzed monosaccharides: fucose, galactose, glucose, arabinose, rhamnose and xylose. Under the selected optimum conditions, the six monosaccharides could be perfectly separated within 25 min and showed significant current responses at copper electrodes. The linear ranges of the six monosaccharides were all from 5.0 x 10(-6) to 2.0 x 10(-4) mol L(-1) and their detection limits were lower or near 1.0 x 10(-6) mol L(-1) (S/N = 3). Experiments showed that the Angelica sinensis polysaccharide was composed of fucose, galactose, glucose, arabinose, rhamnose and xylose (mole ratio 1.0:13.6:15.0:8.7:21.3:3.7), and the flax polysaccharide was composed of galactose, glucose and arabinose (mole ratio 1.0:4.98:1.1). The purity of these polysaccharides leached by the introduced leaching method was 98.3 and 97.6%, respectively. Analyzing polysaccharides by this method has some merits of speed, simple instrumentation and operation, high sensitivity and high reproducibility.     

Structure–property relationship study of the HPLC enantioselective retention of neuroprotective 7‐[(1‐alkylpiperidin‐3‐yl)methoxy]coumarin derivatives on an amylose‐based chiral stationary phase

The enantiomer separation of a number of racemic 7‐[(1‐alkylpiperidin‐3‐yl)methoxy]coumarin derivatives, some of which show outstanding in vitro multitarget neuroprotective activities, was successfully achieved on a polysaccharide‐based chiral stationary phase, bearing amylose tris(3,5‐dimethylphenylcarbamate) as a chiral selector, in normal polar mode (methanol and acetonitrile as the mobile phases). The majority of the screened selectands, especially those bearing 1‐(3‐X‐benzyl)piperidin‐3‐yl moieties, showed baseline enantiomer separations, and compound 8 (X = NO₂) was the best resolved (α = 2.01; R_S = 4.27). Linear free energy relationships, usefully complemented by molecular docking calculations, have the key role in enantioselective retention of aromatic interactions between π‐donor moieties in the chiral selector and π‐acceptor moieties in selectand, strengthened by hydrogen bond interaction between a hydrogen bond donor in the chiral selector and the hydrogen bond acceptor group(s) in the selectand. Statistically, reliable equations highlighted the importance of the substituent's size and substitution pattern (meta better than para) to affect the enantiorecognition of the title compounds. The chromatographic data support the scalability of the optimized experimental conditions for preparative purposes.     

Biologically Active Substances from Cacalia hastate Leaves. 1. Carbohydrates from Leaves and Their Hypoglycemic Activity

Leaves of Cacalia hastate L. (Asteraceae) were composed of free sugars, water-soluble polysaccharides (arabinogalactan type), pectinic substances, hemicelluloses, and cellulose. The hypoglycemic activity was determined for the water-soluble polysaccharides and pectinic substances.     

Medium optimization for polysaccharide production of Cordyceps sinensis

As a potential anticarcinogenic agent, polysaccharides from Cordyceps sinensis have been demonstrated to possess strong antioxidation activity. The aim of the present research was to study the optimal medium to produce polysaccharides of C. sinensis by using response surface methodology (RSM). The composition of optimized medium for polysaccharide production calculated from the regression model of RSM was 6.17% sucrose, 0.53% corn steep powder, 0.5% (NH₄)₂HPO₄, and 0.15% KH₂PO₄ at pH 4.44, with a predicted maximum polysaccharide production of 3.17 g/L. When applying this optimal medium, the maximum polysaccharide production was 3.05 and 3.21 g/L in a shake flask and a 5-L jar fermentor, respectively. When the pH was controlled at a higher level such as pH 5.0, both cell growth and polysaccharide production were inhibited. A low pH of 2.85 was required for maximum production of polysaccharides.     

海水小球藻中多糖的提取及其单糖组成的气相色谱-质谱分析

在温度为70℃、功率为600 W、提取时间为30 m in的条件下,海水小球藻中的多糖可以得到较好的提取。经过优化,当超声波作用时间为90 m in、超声波功率为300 W、水解液为1 mol/L乙酸时,小球藻多糖的超声水解效果最好。碱提、水提、酸提海水小球藻多糖中的单糖组成,经过GC-MS分析,它们的单糖组成各不相同。碱提粗多糖中所含单糖为鼠李糖、L-岩藻糖、D-阿拉伯糖、D( )-木糖、D-甘露糖、D-葡萄糖、D-半乳糖,各单糖百分含量分别为20.68%、0.32%、1.0%、2.20%、4.58%、50.28%、20.91%(W/W);水提海水小球藻粗多糖中含鼠李糖、核糖、岩藻糖、阿拉伯糖、木糖、甘露糖、葡萄糖、半乳糖8种单糖,它们百分比分别为2.32、2.36、0.24、0.89、0.56、3.44、78.21、11.99%(W/W);酸提粗多糖中所含单糖为鼠李糖、核糖、岩藻糖、阿拉伯糖、木糖、甘露糖、葡萄糖、半乳糖,各单糖百分含量分别为2.75、1.75、0.23、1.04、0.61、5.99、74.33、13.30%(W/W)。本实验所建立的微波辅助提取、超声水解多糖、GC-MS分析多糖中的单糖组成等方法,具有简便、快速、准确的特点。可用于海藻和其它植物中的多糖研究。     

New polysaccharide-g-polyacrylonitrile copolymers: synthesis and thermal characterization

Various natural and modified polysaccharides (i.e. arabic gum, tragacanth gum, xanthan gum, sodium alginate, chitosan, sodium carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose) were modified using ceric-initiated graft polymerization of acrylonitrile under inert atmosphere. Grafting was confirmed using spectral (FT-IR) proofs. The grafting parameters were determined by conventional methods. Thermal characteristics of the homopolymer-free copolymers were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) under nitrogen atmosphere. The major thermal transitions as well as the activation energy of the major decomposition stages were investigated. The polyacrylonitrile (PAN)-grafted polysaccharides were recognized to be thermally stable more than the corresponding non-grafted substrates, although they begin to decompose at relatively lower temperatures than the non-grafted counterparts. Copyright © 2003 John Wiley & Sons, Ltd.