唾液酸单体的HPLC测定及其在唾液酸纯化中的应用

建立了高效液相色谱法测定唾液酸单体的方法,色谱柱为ZORBAX SB C18柱,流动相为pH3的硫酸水溶液,流速1．0mL／min,进样量5．0μL,在波长210nm处检测,唾液酸单体质量浓度与峰面积呈良好的线性关系,相关系数为0．9999。在唾液酸单体的纯化过程中用此方法进行检测;与质谱分析相结合,确立了聚唾液酸水解液中唾液酸二聚体的存在。     

Stereoselectivity investigation on glycosylation of oxazolidinone protected 2-amino-2-deoxy-d-glucose donors based on pre-activation protocol

Diverse 2,3-oxazolidinone protected 2-amino-2-deoxy-d-glucose thioglycosides were prepared and studied as glycosyl donors at low temperature by BSM/Tf₂O pre-activation protocol before the addition of glycosyl acceptors. The stereochemistry outcomes of a series of glycosylations were investigated. Different stereoselectivities of the coupling reactions were obtained, arising from the different protecting groups in the oxazolidinone donors. 4,6-Di-O-benzyl-N-benzyl-oxazolidinone protected thioglycoside donor 1c underwent glycosylation with general β-anomeric selectivity and the stereoselectivity could be also affected by glycosylation conditions.     

奶粉中唾液酸的测定方法

利用酸水解把奶粉中的唾液酸释放出来,通过聚丙烯酰胺凝胶除去奶粉中大量乳糖的干扰。利用Cu^2＋和Cr^3＋协同催化唾液酸与间苯二酚的显色,用乙酸丁酯-正丁醇萃取有色物质,在610nm处测定牛奶中唾液酸含量。方法的线性范围0～55．90mg／L,回收率为94％～96％。     

The Isothiocyanato Moiety: An Ideal Protecting Group for the Stereoselective Synthesis of Sialic Acid Glycosides and Subsequent Diversification

The preparation of a crystalline, peracetyl adamantanyl thiosialoside donor protected by an isothiocyanate group is described. On activation at ?78 °C in the presence of typical carbohydrate acceptors, this donor gives high yields of the corresponding sialosides with exquisite α‐selectivity. The high selectivity extends to the 4‐O‐benzyl‐protected 3‐OH acceptors, which are typically less reactive and selective than galactose 3,4‐diols. Treatment of the α‐sialosides with tris(trimethylsilyl)silane or allyltris(trimethylsilyl)silane results in replacement of the C5? N5 bond by a C? H or a C? C bond. The reaction of the isothiocyanate‐protected sialosides with thioacids generates amides, while reaction with an amine gives a thiourea, which can be converted into a guanidine. The very high α‐selectivities observed with the new donor and the rich chemistry of the isothiocyante function considerably extend the scope for optimization at the sialoside 5‐position.     

对巯基苯硼酸修饰石英晶体微天平传感器用于测定唾液酸

硼酸与二醇的脱水缩合反应已被广泛用于检测或富集顺式邻位多羟基化合物. 本文以对巯基苯硼酸(MPBA)自组装修饰石英晶体微天平(QCM)芯片, 基于硼酸根对唾液酸的特殊反应, 建立了检测唾液酸(SA)的新方法. 采用扫描电子显微镜表征了对巯基苯硼酸对石英晶体微天平的功能化修饰过程, 并研究了溶液pH值对芯片表面亲和力的影响. 实验结果表明, 随着pH值的降低, 修饰芯片对唾液酸的结合能力增强, 而对参照物葡萄糖的结合能力则降低. 在pH=4.0的条件下, 该传感器在0.50~5.0 mmol/L范围内对唾液酸有很好的线性响应, 相关系数为0.9950, 检出限为0.15 mmol/L. 此传感器提供了一种简易的唾液酸检测方法, 为实际样品的测定奠定了基础.     

协同催化光度法测定血清中唾液酸

本文利用Ｃｕ＾２＋和Ｃｒ＾３＋的协同催化作用及Ｂｒｉｊ３５的增溶作用建立了测定唾液酸的光度分析新方法，该方法的线性范围为０～９８０ｍｇ／Ｌ，检出限为１．５ｍｇ／Ｌ，相对标准偏差为１．８３％～２．６６％，回收率为９４．７％～１０２．０％，用于测定人血清中的唾液酸，获得满意结果。     

Convenient Synthesis and Purification of N-Trifluoroacetylated Neuraminic Acid Tetraol: A Key Precursor for the Synthesis of New Sialyl Donors Containing Labile O-Acyl Protecting Groups

A convenient synthesis and separation of α- and β-anomers of methyl (phenyl 3,5-dideoxy-2-thio-5-trifluoroacetamido-D-glycero-D-galacto-nonulopyranosid)onate (6a and 6b) on a multigram scale was developed. Both α- and β-isomers of 6 were obtained as crystals suitable for safe storage. The β-isomer forms a crystalline solvate with methanol. Fully O-trichloroacetylated and O-trifluoroacetylated N-trifluoroacetyl thiosialosides were synthesized in an efficient manner from the β-tetraol 6b.     

β-Selective Glucosylation in the Absence of Neighboring Group Participation: Influence of the 3,4-O-Bisacetal Protecting System

A 3,4-O-bisacetal 2,6-di-O-benzyl protected thioglucoside is converted to the corresponding glucosyl triflate with 1-benzenesulfinyl piperidine and trifluoromethanesulfonic anhydride. The moderate to excellent β-selectivity exhibited with this glucosyl triflate with a range of alcohols is generally higher than that observed with the more electronically disarmed corresponding 3,4-O-carbonate, for which a possible reason is advanced.     

在线富集胶束电动色谱法测定唾液中的唾液酸

建立了1种测定唾液酸的在线富集胶束电动色谱法。首先研究了不同的表面活性剂(十二烷基硫酸钠、胆酸钠和脱氧胆酸钠)、背景电解质(磷酸盐、硼砂和3—环己胺—1—丙烷磺酸)、缓冲溶液的pH值及有机修饰剂(甲醇和乙腈)的加入对测定唾液酸的影响;其次研究了样品基体的组成及进样时间对富集效果的影响;最后考察了所建立方法的线性、检出限和重复性,并将该方法成功地应用于测定人体唾液中的唾液酸,在12min内完成分离。     

Quantifying the Efficiency of N-Phenyl-D-mannosamine to Metabolically Engineer Sialic Acid on Cancer Cell Surface

A convenient method was developed for the quantification of sialic acids expressed by cells and used to analyze the efficiency of N-phenylacetyl-D-mannosamine (ManNPhAc) to metabolically glycoengineer SKMEL-28 cancer cells. For this purpose, ManNPhAc-cultured cells were treated with 2M acetic acid to release sialic acids, and the products were treated with 1,2-diamino-4,5-methylenedioxybenzene to form the corresponding derivatives that had strong UV absorptions. The reaction mixture was then applied to HPLC-UV analysis to determine the amounts and the ratios of natural sialic acid and its unnatural analog. It was confirmed that after incubation with ManNPhAc, the SKMEL-28 cell was effectively glycoengineered to express a significant amount of unnatural sialic acid.     

糖苷和寡糖的立体选择性合成研究进展

精苷、寡糖的立体选择性合成是一个十分重要的课题. 本文结合作者的研究工作介绍了糖苷、寡糖的立体选择合成的方法学进展,主要涉及近年来合成寡糖的新方法,并对这些方法的优势及不足进行了评述.     

Synthesis of the starfish ganglioside AG2 pentasaccharide

This Letter reports the first synthesis of the AG2 pentasaccharide, using silylene-oxazolidinone double-locked sialic acid building blocks. The di-DTBS-protected sialic acid building block was easily prepared and readily activated with NIS and TfOH to provide the sialylated lactose unit in good yield with moderate selectivity. After obtaining the trisaccharide unit, the oxazolidinone-protected C4-OH on the sialic acid residue was readily deprotected by treatment with NaOMe. Coupling with the galactofuranosylβ(1-3)galactopyranosyl fluoride building block produced the desired AG2 pentasaccharide in a highly stereoselective manner. Finally, the desired AG2 pentasaccharide was obtained in good yield following global deprotection.     

Synthesis of flavonoid 2-deoxyglucosides via the Mitsunobu reaction

The Mitsunobu reaction of flavonoids and 3,4,6-tri-O-acetyl-2-deoxy-d-glucopyranose or 3,4,6-tri-O-benzyl-2-deoxy-d-glucopyranose is a very effective method for the stereoselective synthesis of flavonoid 2-deoxyglucosides. Since there is no C2 substituent on the sugar moieties, the observed α- or β-stereoselectivity was mainly controlled by the (acetyl or benzyl) protecting groups. Possible mechanistic insights are offered to explain the dual stereoselectivity.     

Synthesis and Hemolytic Properties of Glycyrrhetic Acid Glycosides

Summary.  The synthesis of monodesmosidic glycyrrhetic acid disaccharides via its diphenylmethyl ester is described. Their hemolytic activity is lower as compared to the corresponding oleanolic aciddisaccharides. The influence of the structure of the aglycon on the hemolytic activity is discussed. Received November 18, 1999. Accepted November 30, 1999     

Allyl Protecting Group Mediated Intramolecular Aglycon Delivery (IAD) of Glycosyl Fluorides

Summary.  Stereospecific 1,2-cis-glycosylation of 2-O-allyl protected glucosyl and mannosyl fluorides can be achieved via a sequence of allyl isomerization, N-iodosuccinimide mediated tethering, and intramolecular aglycon delivery (IAD). Fluoride is advantageous as an anomeric leaving group since extended reaction times can be employed to tether hindered aglycon alcohols without competitive anomeric activation. Tin(II) chloride mediated intramolecular glycosylation furnishes the desired α-glucosides and β-mannosides in an entirely stereoselective manner. Received August 24, 2001. Accepted November 6, 2001     

Modulation of the stereoselectivity and reactivity of glycosylation via (p-Tol)2SO/Tf2O preactivation strategy: From O-, C-sialylation to general O-, N-glycosylation

We make a review on the progress of the (p-Tol)₂SO/Tf₂O preactivation strategy for general glycosylation using thioglycosides or sialyl sulfoxide as donors.     

苯丙素苷Acteoside,Isoacteoside和Ligupurpuroside J的全合成

发展了一条合成苯丙素苷类化合物的通用路线,并依据此路线完成了苯丙素苷毛蕊花糖苷(Acteoside)和异毛蕊花糖苷(Isoacteoside)的全合成及紫茎女贞苷J(Ligupurpuroside J)的首次全合成.其中的关键步骤是应用金(Ⅰ)催化的鼠李糖邻炔基苯甲酸酯给体与多羟基裸露的2-苯乙基葡萄糖苷进行区域选择性糖苷化反应,成功构建天然苯丙素苷中常见的α-(1→3)糖苷键.该合成路线减少了保护基的使用,简洁高效.