榆耳水溶性多糖GIA的结构分析

用6%尿素从榆耳(Gloeostereuminsarnatum)子实体中提取出水溶性粗多糖,经乙醇分级及SeoharoseCL-6B制备柱收集得到组分GIA.经SephadexG-75、DEAE-阴离子交换纤维素和HPLC验证,GIA分子量及极性为均一组分.气相色谱(GC)分析表明,其单糖组成为Xyl,Gal和Glc.HPLC测得平均分子量为18000.经IR、GC、部分酸水解、高碘酸氧化、Smith降解、¹³CNMR、甲基化分析及其产物的GC-MS联机分析表明,GIA为少分支结构,主要由α型糖苷键构成,少部分由β型糖苷键构成;主体结构由Gal和Glc组成,其中主要为Gal1→6,还有Glc1→6;Gal1→6和Glc1→6在3-O处有分支;平均每10个己糖残基有2个分支;GIA的支链部分由Gal1→3和Glc1→3构成;末端残基为Xyl,Gal,Glc.     

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.     

沙棘果皮水溶性多糖H_n的结构研究

沙棘果皮水溶性多糖经酸性乙醇分级和DEAE -SephadexA - 2 5柱层析纯化 ,得到多糖Hn.经SepharoseCL - 4B柱层析、玻璃纤维纸电泳、比旋光度测定等方法鉴定Hn 为均一多糖 .经唾液淀粉酶解、部分酸水解、高碘酸氧化、Smith降解、甲基化分析及IR ,1 3C -NMR ,GC和GC -MS等方法 ,确定其基本结构中主链由 1→ 4Glc基、1→ 6Man基和 1→ 6Gal基构成 .三者摩尔比为nGlc∶nMan∶nGal=3∶1 .5∶1 ,分支点在 3—O处 ,分支率为 43% ,侧链由 1→ 6Gal基、1→ 4Glc基、末端Glc或末端Ara基构成 .     

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.     

小刺猴头菌子实体水溶性多糖HP Ⅱ的结构研究

小刺猴头菌子实体多糖经乙醇分级和Sepharose CL-6B柱层析，得到多糖HPⅡ．经Sephadex G-100柱层析，高压玻璃纤维纸电泳，比旋光度测定等方法鉴定：HPⅡ在相对分子质量大小和极性上都较为均一．经部分酸水解、高碘酸氧化、Smith降解、IR分析、甲基化分析、GC和GC／MS联机分析等方法，确定了其结构：（1→6）Glc构成主链的核心结构，在3-O处有分枝，平均每7个己糖残基有3个分枝残基；A，B为侧链结构，其构成成分为Glc和Gal；末端残基为（1→）Glc．     

松木层孔菌多糖PEP的结构及活性研究

从松木层孔菌发酵菌丝体中分离制备碱提水溶性多糖(PEP).高效液相色谱分析表明,PEP为单一级分,相对分子质量约为1.6×104.GC分析PEP的单糖组成为甘露糖、半乳糖和葡萄糖,其物质的量比为3.11∶1.32∶0.54.PEP经部分酸水解、高碘酸氧化、Smith降解和甲基化分析,其结构主要为β-(1→2)Man且在6-0处构成分枝结构,PEP的支链部分由(1→4)-Man,(1→6)-Gal构成,末端残基为Gal和Glc.初步考察,PEP对小鼠离体淋巴细胞有较显著的促增殖作用.     

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．     

白术水溶性多糖的结构特征

白术(Atractylodes macrocephala Koidz)水溶性粗多糖,经乙醇分级及Sepha-dex G-75层析柱制备得到组分AMP.经Sephadex G-75、DEAE-阴离子交换纤维素层析及HPLC验证,AMP相对分子质量及极性为均一组分,HPLC测得相对分子质量为8 374.气相色谱(GC)分析表明其单糖组成为Glc,Gal,Rha和Man,物质的量比为7.36∶1.00∶3.05∶1.52.多糖AMP经部分酸水解、高碘酸氧化、Smith降解、甲基化分析,其结构主体部分由Glc,Rha和Man组成,平均每6个残基上有1个分支,分支点为Glc的4-O处和Man的6-O处,末端残基为Glc.     

猴头菌发酵菌丝水溶性多糖HPA的结构确定

从被超声波破碎的猴头菌发酵菌丝细胞热水提取液中,经乙醇分级分离得到单一级分,HPA经SepharoseCL-6B柱层析测得其相对分子质量为4 56×105.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以(1→4)糖苷键连接,平均每8个残基上有1个分枝,分枝点在O-3上,分枝末端残基为Glc1—.     

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。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.