几种真菌多糖硫酸酯化修饰前后理化性质的比较研究

制备了平菇等5种真菌类硫酸酯化多糖,离子色谱法测得其含硫量为12%～15%,取代度为1.02～1.46.对其硫酸酯化修饰前后的柱层析行为、电泳行为、红外光谱、圆二色谱、比旋光度、特性黏度进行了系统的比较研究.结果表明,引入硫酸基后,多糖的相对分子质量增大,电泳迁移率增加,红外光谱和圆二色谱出现特征吸收峰,比旋光度发生显著变化,特性黏度明显降低,表明硫酸酯化修饰后多糖的构象发生了显著变化,可能形成了特定的部分有序结构.     

水溶性高支化多糖及硫酸酯衍生物抗癌活性研究

从虎奶菇菌核中提取出一种水溶性高支化葡聚糖,并用氯磺酸和吡啶在无水二甲亚砜中进行硫酸酯衍生化,制备出硫酸酯衍生物.用巴比赛小鼠动物实验研究该多糖及其硫酸酯衍生物的体内抗肉瘤S-180活性,以及用肝癌细胞株HepG2研究体外活性,同时讨论多糖分子尺寸与抗癌活性的关系.通过形态学、组织切片、以及酶联免疫法研究硫酸酯化对多糖抗肿瘤活性的影响.结果表明,支链多糖的均方根旋转半径在42.5~113 nm之间,显示出较高的体内和体外抗肿瘤活性,硫酸酯衍生物的均方根旋转半径在17.8~34.9 nm之间,抗癌活性随其分子尺寸的增大而逐渐提高.多糖及其硫酸酯衍生物能诱导人体肝癌HepG2细胞凋亡,且具有时间依赖性.它们对免疫反应的调节作用可通过肿瘤坏死因子TNF-α来介导.     

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。     

硫酸/氯磺酸混酸酯化壳聚糖的研究

本文讨论了硫酸／氯磺酸混酸硫酸酯化壳聚糖类肝素的反应机理及结构分析。通过硫酸／氯磺酸混酸硫酸酯化壳聚糖类肝素的反应机理及红外谱图和核磁共振谱图的分析，得出了硫酸／氯磺酸混酸与壳聚糖反应主要在6位-OH上的酯化反应。     

鱿鱼墨黑色素络合铁离子的活性研究

通过高速离心法制备了鱿鱼墨黑色素,研究了其与Fe(Ⅲ)的相互作用行为。静态吸附结果表明,黑色素在pH4.0的条件下络合Fe(Ⅲ)最大吸附量为1.33mmol/g。研究了温度、pH值和其他常见盐对黑色素络合铁离子的影响,结果表明,吸附率受温度影响较大,随温度上升而升高;pH为4.0时吸附率最高;不同浓度的氯化钠对黑色素络合Fe(Ⅲ)的影响较小。采用紫外光谱和红外光谱研究表明,鱿鱼墨黑色素在与Fe(Ⅲ)的络合过程中,羧基,羟基和亚胺基的红外特征峰减弱,表明3个官能团都参与了与金属离子的络合。扫描电镜(SEM)图谱表明,鱿鱼墨黑色素与Fe(Ⅲ)络合后,可能发生了氧化还原反应,致使鱿鱼墨黑色素结构遭到一定的破坏。     

高温~1H NMR鉴别8种海参硫酸软骨素

提取了8种海参中的粗多糖,经DEAE-52阴离子交换柱分离纯化得到其中的海参硫酸软骨素(SC-CHS),除日本刺参CHS外其余均为首次获得的海参多糖。对获得的SC-CHS进行分子量、单糖组成及硫酸基含量等基本性质分析后,利用高温1HNMR对SC-CHS结构进行初步鉴别。结果表明,高温条件下SC-CHS的1HNMR图谱具有较好的分辨度。对其支链硫酸化岩藻糖的异头氢进行归属和比较,并以此为指标鉴别不同种类海参硫酸软骨素的结构差异,建立了一种以海参硫酸软骨素结构特征为指标的海参指纹图谱;初步探讨了不同海域生长的海参中硫酸软骨素支链岩藻糖硫酸基的特点,比较发现:寒带海域海参的硫酸软骨素岩藻糖上硫酸基取代以2,4-di OSO3、3,4-di OSO3双取代为主,含部分4-OSO3单取代;温带海域海参以2,4-di OSO3双取代为主,含部分4-OSO3单硫酸基取代;热带亚热带海域海参以2,4-di OSO3双取代和4-OSO单取代为主。这将为海参构效关系的进一步分析鉴定提供理论依据。     

碱处理对紫莱多糖结构与性能的影响

本文研究紫菜半乳聚糖硫酸酯经过碱处理后,其化学组成、溶液流变性质及凝胶理化性质的变化。对处理前、后的多糖应用红外吸收光谱及电子显微镜进行分析,发现由于碱处理使紫菜半乳聚糖硫酸酯的结构转变成3,6-内醚-半乳糖与D-半乳糖交替连结的琼酯糖结构,因而它的各项理化性能均与从其他红藻类原料制得的琼胶一致。     

低分子量硫酸化多糖的体积排阻色谱法分离及其组成定量分析

建立了用于分离并定量测定低分子量硫酸化多糖中不同糖链数的各个组分分布比例的体积排阻色谱方法。系统考察了流动相的组成、离子强度和pH值、流速、柱温等因素对分离的影响。最佳分离条件: 两支TSK-GEL G2000 SWxl色谱柱(300 mm×7.8 mm)串联,流动相100 mmol/L Na2HPO4-NaH2PO4 (pH 7.0),流速0.5 mL/min,柱温35 ℃,进样量5 μL,样品质量浓度10 g/L。在最佳的分离条件下,可以将低分子量硫酸化多糖样品中不同糖链数的各个组分分离并对各个组分的分布进行了定量分析。用该方法对美国药典标准品(USP)、商品和实验室制备的低分子量硫酸化多糖糖链数分布进行了定量化比较,证明该方法可用于低分子量硫酸化多糖类药物的组成成分的质量控制。     

改性硫酸钛催化合成丙酸酯

固体硫酸钛经不同的高温灼烧制得改性硫酸钛，用改性硫酸钛吸附吡啶后的IR光谱表征其表面酸性；用丙酸与多种醇反应考察其酯化催化活性。结果表明，改性硫酸钛表面存在明显的Broensted酸中心；对酯化反应的催化活性高、反应时间短、催化剂可重复使用多次。     

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.     

Synthesis of sulfated dendrimers and studies of their anticoagulant and antiinflammatory activity

Three hyperbranched dendrimers (polyglycidols) and the corresponding sulfated derivatives, differing in the average molecular weight, were synthesized. The compounds obtained were characterized in detail by mass spectrometry and ¹H and ¹³C NMR spectroscopy, enabling estimation of the sizes of the corresponding molecules. Assignment of signals and identification of key structural blocks were performed using 2D homo- and heteronuclear spectroscopy (COSY, HSQC). The spectra of the sulfated derivatives showed the absence of the signals for the glycerol moiety with the free OH groups, that confirms exhaustive sulfation. The studies of antiinflammatory and anticoagulant activities of the polyanionic samples showed that all the compounds manifest weak antiinflammatory activity, however, their anticoagulant activity displayed in preliminary trials seems to be considerable. The results obtained indicate that it is reasonable to study in more detail biological activity of sulfated dendrimers of this type in terms of their anticoagulant properties.     

Synthesis of polymethacrylate derivatives having sulfated maltoheptaose side chains with anti‐HIV activities

Anti‐HIV (human immunodeficiency virus) active polymethacrylates having pendant sulfated oligosaccharides were synthesized, and the relationship between structures and biological activities of the polymethacrylates was examined. Acetylated 1‐O‐methacryloyl maltoheptaoside (MA‐AcM7) was polymerized with AIBN as an initiator to give polymethacrylates having a pendant acetylated maltoheptaose in every repeating unit, poly(MA‐AcM7)s. After hydroxyl groups were recovered by deacetylation, the polymethacrylates having maltoheptaose units, poly(MA‐M7)s, were sulfated to give polymethacrylates having sulfated maltoheptaose side‐chains, poly(MA‐SM7)s, with degrees of sulfation of 1.1 to 2.7 (maximum, 3.0). These polymethacrylates including sulfated oligosaccharides exhibited low anti‐HIV activities represented by the 50% protecting concentration (EC₅₀) in the range of 15–62 μg/mL and low blood anticoagulant activities around 10 unit/mg (standard dextran sulfate, 22.7 unit/mg). The anti‐HIV activity increased with increasing degree of sulfation to reach EC₅₀ of 15–16 μg/mL. In addition, copolymerization of MA‐AcM7 with methyl methacrylate (MMA) and subsequent sulfation gave polymethacrylates consisting of various proportions of highly sulfated maltoheptaose and MMA units. It was revealed that the anti‐HIV activity increased with decreasing proportion of the sulfated oligosaccharide moiety and that a copolymethacrylate having 22 mol % of sulfated maltoheptaose units (DS = 3.0) had a high anti‐HIV activity in the EC₅₀ of 0.3 μg/mL. The blood anticoagulant activity increased slightly from 9 to 18 unit/mg with decreasing proportion of the sulfated maltoheptaose units. These results suggested that the biological activities were influenced strongly by the spatial distance between sulfated oligosaccharide substituents in the polymethacrylate main chain. Distinction and conformation of the oligosaccharide side chains also played an important role. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 789–800, 1999     

Structures and Anticoagulant Activities of the Partially Mild Acidic Hydrolysis Products of the Fucosylated Chondroitin Sulfate from Sea Cucumber Pearsonothuria graeffei

Fucosylated chondroitin sulfate from Pearsonothuria graeffei (fCS-Pg) is a unique glycosaminoglycan (GAG), which was reported to have potent antithrombotic and anticoagulant activities. In the present study, the native fCS-Pg was hydrolyzed by mild acid to improve its bioavailability. The structures of the acid-released and acid-resistant sulfated fucose branches of fCS-Pg before and after acidic hydrolysis were characterized by nuclear magnetic resonance spectroscopy (NMR) technology. The results showed the acid-released fucose residues included both α- and β-fucose conformation, containing 2,4-di-O-sulfated fucose (Fuc2,4S), 3,4-di-O-sulfated fucose (Fus3,4S), 3-O-sulfated fucose (Fuc3S), and 4-O-sulfated fucose (Fuc4S), with a mole ratio of 6:26:22:46, respectively. Their difference to the native fCS-Pg in the sulfation pattern of the backbone could be due to selective removal of the sulfated groups during the release of the fucose branches by acid. For the acid-resistant part, the sulfation patterns of fucose were similar to the native polysaccharides, but the signal strength of Fuc3,4S was obviously decreased, whereas Fuc2,4S was kept unchanged, indicating Fuc3,4S is more liable to acid. The anticoagulant activities of the acid-resistant part were tested in vitro, and the results showed that partial degradation could result in significant reduction of anticoagulant activity, which could help to lower the risk of bleeding when developing fCS as an antithrombotic drug.     

Multi‐stimuli‐responsive self‐immolative polymer assemblies

Self‐immolative polymers (SIPs) undergo depolymerization in response to the cleavage of stimuli‐responsive end‐caps from their termini. Some classes of SIPs, including polycarbamates, have depolymerization rates that depend on environmental factors such as solvent and pH. In previous work, hydrophobic SIPs have been incorporated into amphiphilic block copolymers and used to prepare nanoassemblies. However, stimuli‐responsive hydrophilic blocks have not previously been incorporated. In this work, we synthesized amphiphilic copolymers composed of a hydrophobic polycarbamate SIP block and a hydrophilic poly(2‐(dimethylamino)ethyl methacrylate) (PDMAEMA) block connected by a UV light‐responsive linker end‐cap. It was hypothesized that after assembly of the block copolymers into nanoparticles, chain collapse of the PDMAEMA above its lower critical solution temperature (LCST) might change the environment of the SIP block, thereby altering its depolymerization rate. Self‐assembly of the block copolymers was performed, and the depolymerization of the resulting assemblies was studied by fluorescence spectroscopy, dynamic light scattering, and NMR spectroscopy. At 20 °C, the system exhibited a selective response to the UV light. At 65 °C, above the LCST of PDMAEMA, the systems underwent more rapid depolymerization, suggesting that the increase in rate arising from the higher temperature dominated over environmental effects arising from chain collapse. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1868–1877     

Synthesis of Sulfated Polysaccharides and Oligosaccharide Derivatives with Potent Anti-Aids Virus Activity

Abstract

Sulfated synthetic polysaccharides (with both high anti-AIDS virus activity and high anticoagulant activity) were prepared by sulfating such synthetic polysaccharides as ribopyranan, ribofuranans, and dextrans. Sulfated natural polysaccharides with high anti-AIDS virus activity but low anticoagulant activity were synthesized from lentinan and curdlan. It is assumed that curdlan sulfate will be helpful as an AIDS drug. In addition, sulfated alkyl oligosaccharides with high anti-AIDS virus activity were prepared.     

Engineered bio-active polysaccharides from heparin

[Image: see text] Heparin, the well-known anticoagulant polysaccharide, is also active in many other biological systems owing to its structural similarity to HS, but usually lacks selectivity because it is more highly sulfated. A series of straightforward chemical reactions (de-O-sulfation, de-N-sulfation and re-N-acetylation), carried out to partial or complete extent, were combined, resulting in a number of modified heparin polysaccharide derivatives with altered properties. These exhibited a range of abilities to promote cell signalling through the FGF/FGFR tyrosine kinase signalling system, in an in vitro cell assay with combinations of FGF-1, -2, -3 and FGFR 1 and 3. One polysaccharide (N-acetylated, 6-O- and 2-O-sulfated heparin), with only a fraction (<10(-3)) of the anticoagulant activity of heparin (200 U . mg(-1)), promoted FGF-2-mediated angiogenesis (10-fold) and therefore had an improved ratio of pro-angiogenic activity to anticoagulant activity in excess of 10(4) compared to heparin. These results demonstrate that heparin-derived polysaccharides can be engineered for selected activities and have potential in a wide range of medical, biotechnological and tissue-engineering applications. Effect of selected engineered heparin polysaccharides on angiogenesis.     

Isolation and Characterization of Low Molecular Weight Glycosaminoglycans from Marine Mollusc Amussium pleuronectus (Linne) using Chromatography

The glycosaminoglycan (GAG) heparin is a polyanionic sulfated polysaccharide most recognized for its anticoagulant activity. In the present study, the GAGs were extracted from bivalve mollusc Amussium pleuronectus. The crude GAGs were fractionated by ion-exchange (DEAE-cellulose and Amberlite IRA-900 & 120) chromatography. The recovered active fractions (as determined by metachromatic assay) were confirmed by agarose gel electrophoresis and the active fractions were purified in Sephadex G-100 column. Fractionated and purified GAG molecular weight was determined through gradient polyacrylamide gel electrophoresis. The structural characterization of low molecular weight GAG was analyzed by Fourier transform infrared spectroscopy. The activated partial thromboplastin time of purified GAG is 95 IU/mg and has molecular weight 6,500–7,500 Da. The disaccharide compositional analysis on the GAG sample was sulfated like porcine intestinal mucosal heparan sulfate, and it contains equivalent amount of uronic acid and hexosamine. The results of this study suggest that the GAG from A. pleuronectus could be an alternative source of heparin.     

Temperature effects on ion association and hydration in MgSO4 by dielectric spectroscopy.

A detailed investigation of aqueous solutions of magnesium sulfate has been made by dielectric relaxation spectroscopy (DRS) over a wide range of frequencies (0.2 MgSO(4) (0)(aq) is in good agreement with literature data at lower temperatures but is overestimated at higher temperatures due to processing difficulties. Despite the limited precision of the spectra, analysis of the individual steps in the ion-association process is possible for the first time. The 2SIPs are formed with little disturbance to their hydration shells, the (partial) destruction of which appears to occur mostly during the formation of SIPs. Effective hydration numbers derived from the DRS spectra indicate that both Mg(2+) and SO(4) (2-) influence solvent water molecules beyond their first hydration spheres but that MgSO(4)(aq) is less strongly hydrated than the previously studied CuSO(4)(aq).     

Effect of O-glycosylation and tyrosine sulfation of leech-derived peptides on binding and inhibitory activity against thrombin

Synthesis of sulfated and unsulfated (glyco)peptide fragments of Hirudin P6 (a potent anticoagulant from the leech Hirudinaria manillensis) is described. The effect of O-glycosylation and tyrosine sulfation on thrombin binding and peptidolytic activity was investigated, together with the inhibition of fibrinogen cleavage.     

Purification,Characterization, and Structural Studies of a Sulfatase from Pedobacter yulinensis

Sulfatases are ubiquitous enzymes that hydrolyze sulfate from sulfated organic substrates such as carbohydrates, steroids, and flavones. These enzymes can be exploited in the field of biotechnology to analyze sulfated metabolites in humans, such as steroids and drugs of abuse. Because genomic data far outstrip biochemical characterization, the analysis of sulfatases from published sequences can lead to the discovery of new and unique activities advantageous for biotechnological applications. We expressed and characterized a putative sulfatase (PyuS) from the bacterium Pedobacter yulinensis. PyuS contains the (C/S)XPXR sulfatase motif, where the Cys or Ser is post-translationally converted into a formylglycine residue (FGly). His-tagged PyuS was co-expressed in Escherichia coli with a formylglycine-generating enzyme (FGE) from Mycobacterium tuberculosis and purified. We obtained several crystal structures of PyuS, and the FGly modification was detected at the active site. The enzyme has sulfatase activity on aromatic sulfated substrates as well as phosphatase activity on some aromatic phosphates; however, PyuS did not have detectable activity on 17α-estradiol sulfate, cortisol 21-sulfate, or boldenone sulfate.