大豆戊聚糖的化学结构及对面团流变学特性的影响

用1molk/L NaOH提取并经层析柱的分级与提纯, 从大豆细胞壁物质中提取出的戊聚糖纯组分(PRF5-1, PRF5-2)属于多糖-多肽复合物。由β(1→4)-糖苷键连的木聚糖构成多糖部分的主链结构, 主链上部分Xyl残基分别通过3-C与2-C分支点连有Ara和GlcA作为侧链。大戊聚糖对面团流变学特性(粉质特性与拉伸特性)有明显的改良作用, 是一种潜在的面粉品质改良剂。     

大豆木糖葡聚糖的结构研究

利用4mol·dm^-^3NaOH提取结合层析柱提纯, 从大豆细胞壁物质(膳食纤维)中分离出PRF6聚合物组分(即木糖葡聚糖)。通过酸水解、酸部分水解、纤维素酶降解和甲基化等分析方法, 借助气相色谱和色质联用等现代仪器, 对该组分的结构特征作了详尽的剖析。结果表明其主链结构是由β(1→4)糖苷键连接的葡聚糖, 主链在6-C位置带有吡喃木糖残基作为侧键, 部分木糖残基在2-C位置还连有阿拉伯呋喃糖或半乳吡喃糖残基。     

独脚金水溶性多糖的结构表征及其清除自由基活性

独脚金粗多糖(Strigaasiatica(L.)O.Ktze. polysaccharide,SKPc)经DEAE-Sephadex A-25以及Sephadex G-100柱层析分离纯化后得到独脚金多糖组分(SKP~*_1)。采用高效液相色谱(HPLC)法检测SKP~*_1,表明多糖SKP~*_1极性、相对分子质量是均一的,且其相对分子质量为14852u。采用气相色谱(GC)分析法研究SKP~*_1的单糖组成为葡萄糖(Glu)、阿拉伯糖(Ara)、半乳糖(Gal)、木糖(Xyl)、甘露糖(Man)、鼠李糖(Rha),相对摩尔比是2.5∶2.0∶0.85∶0.4∶0.5∶1.0;可能主要以β型糖苷键连接。采用化学分析和仪器分析结合进行SKP~*_1结构分析,表明SKP~*_1结构是Ara以β-(1→3)糖苷键连接构成主链之一,2,4或2,5位有支链;Gal以β-(1→6)糖苷键连接构成SKP~*_1的主链之一,且在3位上有分枝。支链由β-(1→4或1→5)Xyl、β-(1→4,1→6,1→2)Glc构成。Rha、Ara、Man、Gal、Glc都有一部分构成糖分子的末端残基。体外清除羟基实验结果表明,SKP~*_1有较好地清除羟基自由基的活性。     

灵芝多糖的结构特征分析

采用沸水回流法从灵芝子实体中提取多糖,经Sevage法除蛋白,乙醇沉淀,离心、透析、膜分离,浓缩、冻干后得灵芝多糖。经HIO4氧化、Smith降解及甲基化反应,并利用多糖及刚果红混合液在碱性溶液中的波长的红移变化,通过UV-VIS,IR,GC,GC-MS,NMR对灵芝水提多糖的结构特征及三螺旋体结构进行分析研究。结果表明:灵芝多糖含有三螺旋体构型,GC-MS分析灵芝多糖的主要单糖组分为葡萄糖,还有少量的半乳糖、甘露糖、木糖和艾杜糖,IR及1HNMR分析多糖为β-构型,HIO4氧化、Smith降解和甲基化分析表明:多糖主要为(1→3)糖苷键连接构型,并伴有少量的1→6位支链键连接的结构,灵芝多糖是由D-葡萄糖单元通过β-(1→3)糖苷键连接葡聚多糖,其主要构型特征为(1→3)β-D-线性连接的骨架结构。     

玉米芯酸提水溶性多糖CCCP的分离纯化和结构研究

玉米芯用PH=3的HCl煮提得到酸提水溶性粗多糖．该粗多糖组成为Glc，Xyl，Gal，经乙醇分级和Sepharose CL-6B柱层析纯化，得到多糖CCCP．经Sephadex A-25柱层析、比旋光度测定、醋酸纤维薄膜电泳等方法鉴定CCCP为均一多糖．经唾液淀粉酶解、纤维素酶解、部分酸水解、高碘酸氧化、Smith降解、甲基化分析及IR，GC和GC／MS等方法分析表明：CCCP为少分枝结构；主链由吡喃型(1→3)Xyl构成，在O(4)处有分枝；支链主要由(1→4)Glc构成，在O(6)处有分枝，支链还存在1→3，1→6键型连接的Glc，Gal；末端基为Xyl，Glc，Gal．     

碱提猴头发酵菌丝体水溶性多糖HPP的结构确定

从猴头发酵菌丝体水提后残渣中用碱提出了水溶性粗多糖,对其分级纯化得到纯样HPP,SepharoseCL-6B柱层析测得其相对分子质量约为6 53×104,G C 分析表明,其单糖组成为Glc;经部分酸水解、高碘酸氧化、Smith降解和甲基化分析确定此多糖为多分枝结构,其中(1→6)Glc构成主链的核心结构;分支点为O-3;支链部分由(1→3)Glc构成,并连接一端基Glc.     

波谱分析在沙棘果多糖Hn结构研究中的应用

以波谱分析为主要手段研究沙棘果多糖Hn的结构，GC分析表明Hn由Ara，Gal，Man和Glc组成，单糖物质的量比与利用GC分析Hn甲基化产物的结果一致．^13C—NMR分析表明Hn中存在α，β型糖苷键．利用GC—MS分析进一步确定Hn主链结构由β（1→4）Glc，β（1→6）Man和β（1→4）Gal构成，在3-O处有分支，支链由α（1→4）Glc，（1→6）Gal或末端Ara，Glc构成．     

玉米芯水溶性多糖的分离纯化和抗凝血活性研究

从玉米芯中提取到水提水溶性粗多糖,通过乙醇分级、冻融、凝胶过滤层析,生物测定导向等手段,分离到一种能延长体外凝血时间,而且具有外源抗凝血功能的多糖CCⅢ.CCⅢ对活化部分凝血酶原时间(APTT)无显著影响,但可显著延长体外抗凝血时间(PT).将CCⅢ纯化,经糖组成分析、甲基化、高碘酸氧化、Smith降解和GC-MS分析,确定该多糖结构为:β-(1→4)Glc,(1→3)Xyl构成主链,Glc在6-O处有分枝.平均每10个糖残基有1个分枝,支链由β-(1→3)Xyl,(1→3)Glc构成.     

一种刺松藻来源的硫酸阿拉伯聚糖的制备及特征结构表征

刺松藻(Codium fragile)经水提-醇沉获得粗多糖, 进一步将刺松藻粗多糖(CFP) 通过Q-Sepharose Fast Flow(QFF) 阴离子交换柱纯化得到6个多糖组分CFP1CFP6, 其中, 在CFP6中发现纯度较高的阿拉伯聚糖. 采用高效凝胶渗透色谱与十八角激光散射仪联用法和1-苯基-3-甲基-5-吡唑啉酮(PMP)柱前衍生高效液相色谱法对CFP6的分子量及单糖组成进行了分析. 结果表明, CFP6是一种分子量为79290的多糖, 由阿拉伯糖(Ara)和半乳糖(Gal)组成, 二者摩尔比为14.8:1.0. 通过多维核磁共振波谱、 液相色谱-质谱联用及二级质谱等方法对CFP6的糖苷键连接方式及其寡糖序列结构进行表征, 进一步阐明了该复杂多糖的特征结构. 经判断, CFP6主链由Ara组成, 通过 β-(1→3)糖苷键连接, 在Ara的C2位存在分支结构, 硫酸基位于Ara的C4或C2位.     

黄芪药渣中阿拉伯木聚糖(AX-Ⅰ-1)的提取纯化、结构分析及体外抗氧化作用

黄芪药渣经分级提取,再通过二乙氨乙基(DEAE)-纤维素52阴离子交换柱层析和Sephacryl S-400HR凝胶柱层析分离纯化,得到4个多糖组分AX-Ⅰ-1~AX-Ⅰ-4.对多糖AX-Ⅰ-1的理化性质和结构进行研究发现,AX-Ⅰ-1含有鼠李糖、阿拉伯糖、木糖、甘露糖、葡萄糖和半乳糖(摩尔比为0.006∶14.113∶8.284∶0.116∶0.468∶1),主链由阿拉伯糖和木糖通过β-(1→2),(1→3)和(1→4)苷键组成,支链由(1→4)βArap,(1→3)βGalp和(1→2)βMan组成,非还原末端由αRhap,βGclp和βGalp组成.对多糖AX-Ⅰ-1~AX-Ⅰ-4的抗氧化研究结果表明,这4个组分对羟基自由基、超氧阴离子自由基和1,1-二苯基-2-三硝基苯肼(DPPH)自由基均有一定的清除作用;当浓度为0.1 mg/m L时,多糖AX-Ⅰ-2~AX-Ⅰ-4对超氧阴离子的清除率是阳性对照维生素C(Vc)的2倍.     

Facile and Effective Synthesis of Glucopyranosyl Oligosacchardes with Alternative (1→3)-α- and -β-Linkages in the Presence of C-2 Ester Capable of Neighboring Group Participation

β (1→ 3) Ｌｉｎｋｅｄｇｌｕｃａｎｓｏｃｃｕｒｉｎａｖａｒｉｅｔｙｏｆｂｉｏ ｌｏｇｉｃａｌｌｙｉｍｐｏｒｔａｎｔｎａｔｕｒａｌｐｒｏｄｕｃｔｓ ,ｓｕｃｈａｓａｎｔｉｔｕｍｏｒｓｃｈｉｚｏｐｈｙｌｌａｎ ,ｓｃｅｒｏｇｌｕｃａｎａｎｄｌｅｎｔｉｎａｎ ,1ｗｈｉｌｅα (1→3) ｌｉｎｋｅｄｇｌｕｃａｎｓｅｘｉｓｔｉｎｓｏｍｅｍｅｄｉｃａｌｌｙｉｍｐｏｒｔａｎｔｆｕｎｇｉｓｕｃｈａｓＣｒｙｐｈｏｎｅｃｔｒｉｎｉｐａｒａｓｉｔｉｃａａｎｄＧａｎｏｄｅｒｍａｌｕ ｃｉｄｕｍ .2 Ｆｏｒａｓｔｕｄｙｏｎｔｈｅ…     

ISOLATION AND STRUCTURAL ANALYSIS OF NEW FRUCTANS PRODUCED BY CHICORY

This report describes a new series of oligosaccharides, which is formed in chicory roots under forcing conditions and during in vitro experiments using purified chicory 1-FFT (fructan:fructan 1-fructosyl transferase). It was demonstrated that the three smallest members of this new series (disaccharide, trisaccharide and tetrasaccharide) contain exclusively β-D-fructosyl residues after hydrolysis. The present data demonstrate that the smallest compound is levanbiose and that the other oligomers of this new series of fructans do not belong to the linear 2→6 linked levan-oligosaccharides nor to the linear 2→1 linked inulo-oligosaccharides. A combination of several chromatographic techniques yielded a fraction that contained only the compound with degree of polymerisation (DP) 2 (levanbiose, β-D-fructofuranosyl-(2→6)-D-fructofuranose), and a mixture of DP 3 of the new series and 1-kestose. Using homonuclear and heteronuclear 2D NMR experiments the complete ¹H and ¹³C NMR assignments of levanbiose and DP 3 were obtained. From High Performance Anion Exchange Chromatography (HPAEC) and NMR experiments of DP 3 of the new series it was concluded that the molecule contains a β-D-fructofuranosyl residue 2→1 linked to the non-reducing moiety of levanbiose, and thus has to be named β-D-fructofuranosyl-(2→1)-β-D-fructofuranosyl-(2→6)-D-fructofuranose. The simple and regular pattern of the HPAEC retention times of the new oligosaccharides suggests that it is a homologous series of oligomers build by 2→1 elongation with β-D-fructofuranosyl residues at the non-reducing residue of levanbiose.     

Highly Efficient Regio- and Stereoselective Synthesis of β-（1 →6）-Branched β-（1 →3）-Linked Glucohexaose and Its Analogue

A β-（1→）6）-branched β-（1→）3）-linked glucohexaose （1） and its lauryl glycoside （2）, present in many biologically active polysaccharides from traditional herbal medicines such as Ganoderma lucidum, Schizophyllum commune and Lentinus edodes, were highly efficiently synthesized. Coupling of 2,3,4,6-tetra-O-benzoyl-β-D-glucopyranosyl- （1--）3）-2-O-benzoyl-4,6-O-benzylidene-a-D-glucopyranosyl trichloroacetimidate （7） with 3,6-branched acceptors 8 and 12 gave β-（1→）3）-linked pentasaccharides （9） and （13）, then via simple chemical transformation 4＇,6＇-OH pentasaccharide acceptors 10 and 14 were obtained. Regio- and stereoselective coupling of 3 with 10 and 14 gave β-（1→）3）-linked hexasaccharides （11） and （15） as the major products. Deprotection of 11 and 15 provided the target sugar 1 and 2. Thus, a new method for the preparation of this kind of compounds was developed.     

Spectres RMN des Polysaccharides et de leurs Dérivés: Influence des Substituants sur le Déplacement Chimique 13C

Methyl and acetyl substituent effects on ¹³C chemical shift have been determined on (α 1→3), (α 1→4), (β 1→3) and (β 1→4) linked polysaccharides such as pseudo-nigerane, β-cyclodextrine, amylose, laminarane and cellulose. Methyl α- and β-D -glucopyranoside have been used as monomer model compounds. Shift determination of hydroxylated and substituted polysaccharides requires unambiguous assignment of their ¹³C spectra. Selective heteronuclear spin decoupling and the isotope effect of deuterated hydroxyl have been used as assignment techniques.     

Structural characterization of a glucan from Angelica sinesis (Oliv) Diels

Angelica sinesis (Oliv) Diels is a traditional Chinese drug used clinically in the treatment of gynecological diseases. Its polysaccharide fraction been reported to have several immunomodulating, antitumor, antiradiation activities^[1] and a recent paper showed it could obviously act on the hemopoietic system^[2]. Haruki Y. et al. have elucidated the chemical structure of a α(1→4) linked D-glucan from Angelica acutiloba^[3]. We now describe the structure of a water soluble glucan, AS-1, which was isolated and purified from the water extract of Angelica sinesis (Oliv) Diels. It is only composed of D-glucose and its mean molecular weight is estimated to be 5.3×10⁵. The absorption peak of 846cm^-1 on IR, the chemical shift of δ 99.98 ppm for C-1,and the 168 Hz of ¹J_C-H suggested that the D-glucose residues were α-linked. Methylation analysis (Table 1),periodate oxidation, Smith degradation, ¹H NMR and ¹³C NMR (Table 2) showed that it is α(l→6) linked D-glucan to which are attached two glucosyl side chains, Glc-(l→3)-Glc→1 and Glc-(1→4)-Glc→1, both at 3-O of the glucosyl residues of every 14th glucose units of the main chain. The structure was further proved by using HMBC,HMQC and DQF-COSY techniques. The details of its pharmacological results will be published elsewhere.     

A 270 MHz 1H-NMR study of three “branched” ribonucleotides A2'p5'U3'p5'g,A2'p5'C3'p5'G and A2'p5'G3'p5'G the importance of being branched with a 2'→5' phosphodiester bond in the pre-mRNA processing reactions (splicing)

Conformational studies with three analogues 3, 4 and 5 of naturally-occurring branched ribonucleotides 1 and 2 have shown that they adopt a secondary structure which is overwhelmingly controlled by a stacking between adenine(2' → 5')nuc1eobase residues while the 3' → 5' linked guanine residue is apart. This observation along with the fact that all four nucleosides can form lariats in nuclear mRNA splicing, but it is guanosine as the 2' → 5' nucleotide that can drive the splicing reaction to completion, suggests a biological significance of the additional 2' → 5' phosphodiester bond formation in the splicing reaction. It is likely that the final implication of formation of such a 2' → 5' linked lariat is that it provides a pathway to assume a free energy minimum conformation through the 2' → 5' stacking, especially in the case of guanosine, to drive the splicing reaction to completion (stacklng-driven-energy-pump).     

黑小麦麦麸戊聚糖的部分酸水解特征与甲基化分析

研究了黑小麦麦麸戊聚糖(AEPH)的部分酸水解特征及其糖链的取代度和取代方式等结构信息. 分别采用0.02, 0.1和0.2 mol/L的三氟乙酸(Trifluoroacetic acid, TFA)对AEPH进行部分酸水解, 结合甲基化分析、 GC-MS和HPLC等方法对AEPH的糖链结构和相对分子质量分布进行了分析. 结果表明, 戊聚糖AEPH的糖残基主要由阿拉伯糖(Araf)和木糖(Xylp)组成. 其取代度(A/X), 即Araf与Xylp的比值为0.60, 并具有较高的相对分子质量(M_w=3.81×10⁵). AEPH的主链由Xylp残基通过1→4连接形成木聚糖. 主链Xylp在O2, O3或O2/O3位被Araf单取代或双取代. 非取代(u)、 单取代(m)和双取代(d)Xylp残基的组成比例为57.7∶22.0∶6.2. 非取代与取代Xylp的比值为2.1, 双取代与单取代Xylp比值(d/m)为0.3. Araf主要以非还原性末端T-Araf以及通过1→2和1→5连接形成低聚阿拉伯糖的形式与主链Xylp相连, 或与T-Xylp相连形成戊聚糖分子的支链.