Propane-1,2,3-triyl tris(hydrogen sulfate): A mild and effcient recyclable catalyst for the synthesis of biscoumarin derivatives in water and solvent-free conditions简

A simple, efficient, and ecofriendly procedure has been developed using propane-l,2,3-triyl tris（hydrogen sulfate） as a catalyst for the synthesis of biscoumarin derivatives in water and solvent-free conditions. The significant features of the present protocol are simplicity, environmentally benign, high yields, no chromatographic separation, and recyclability of the catalyst.     

One-pot synthesis of various xanthene derivatives using ionic liquid 1, 3-disulfonic acid imidazolium hydrogen sulfate as an efficient and reusable catalyst under solvent-free conditions

In this study, 1,3-disulfonic acid imidazolium hydrogen sulfate （DSIMHS） is used as an efficient and reusable ionic liquid for the green, mild, and efficient synthesis of xanthenes under solvent-free conditions. Simple and easy work-up, low cost, green process, short reaction times and excellent yields of the products are the advantages of this procedure. Further, the catalyst can be recycled and reused at least for four times without a noticeably decrease in its catalytic activity.     

(英)硫酸氢钾高效催化一锅法合成5-未取代的3,4-二氢嘧啶-2(1H)-酮

无溶剂条件下,硫酸氢钾可有效催化芳香醛、苯乙酮衍生物和脲的三组分"一锅法"Biginelli反应来合成5-未取代的3,4-二氢嘧啶-2(1H)-酮。确定了优化反应条件。产品结构经IR、1H NMR、MS和元素分析进行表征。     

Preparation and Crystal Structure of a New Uranyl Sulfate Templated by a Bis-isothiouronium Cation

Crystals of a new uranyl sulfate (C₂N₄H₈S₂)[UO₂(SO₄)₂] · 0.3H₂O ( 1 ) templated by a relatively rare bis-isothiouronium cation, were formed upon evaporation of aqueous solutions containing uranyl acetate, thiourea, and excess sulfuric acid. The new compound is orthorhombic, P2₁2₁2₁, a = 6.928(2) Å, b = 13.398(3) Å, c = 15.225(3) Å, Z = 2. Its crystal structure is comprised of [UO₂(SO₄)₂] moieties linked by hydrogen bonds formed between the template cations and terminal oxygen atoms of the sulfate tetrahedra. The C₂N₄H₈S₂²⁺ template is most likely formed in situ during a redox reaction between uranyl cation and thiourea in a strongly acidic medium, with UO₂²⁺ partially reduced to U⁴⁺.     

3‐O‐Sulfation of Heparan Sulfate Enhances Tau Interaction and Cellular Uptake

Prion‐like transcellular spreading of tau in Alzheimer's Disease (AD) is mediated by tau binding to cell surface heparan sulfate (HS). However, the structural determinants for tau–HS interaction are not well understood. Microarray and SPR assays of structurally defined HS oligosaccharides show that a rare 3‐O‐sulfation (3‐O‐S) of HS significantly enhances tau binding. In Hs3st1^?/? (HS 3‐O‐sulfotransferase‐1 knockout) cells, reduced 3‐O‐S levels of HS diminished both cell surface binding and internalization of tau. In a cell culture, the addition of a 3‐O‐S HS 12‐mer reduced both tau cell surface binding and cellular uptake. NMR titrations mapped 3‐O‐S binding sites to the microtubule binding repeat 2 (R2) and proline‐rich region 2 (PRR2) of tau. Tau is only the seventh protein currently known to recognize HS 3‐O‐sulfation. Our work demonstrates that this rare 3‐O‐sulfation enhances tau–HS binding and likely the transcellular spread of tau, providing a novel target for disease‐modifying treatment of AD and other tauopathies.     

水生动物及水产品中硫丹及其代谢物残留量的气相色谱-质谱测定

建立了水生动物及水产品中农药硫丹及其代谢物残留量的气相色谱-质谱(GC-MS)测定方法;样品经溶剂提取、凝胶层析柱净化;以氦气为载气,甲烷气为反应气,程序升温及负化学源(NCI)电离方式,采用气质联用仪在选择离子监测模式下进行快速测定,保留时间和离子相对丰度比定性、外标法定量;方法定量下限为0.004 mg/kg。在鳗鱼、泥鳅、鲶鱼、虾4种样品中添加不同浓度的硫丹时,其平均添加回收率在71%~87%之间,相对标准偏差(n=10)小于10%。     

毛细管电泳法快速测定复方地芬诺酯片中的地芬诺酯和阿托品

建立了毛细管电泳高频电导法同时测定地芬诺酯和阿托品的方法。探讨了缓冲溶液、有机溶剂添加剂、分离电压和进样条件以及毛细管内径和长度等因素对分离检测的影响。在电泳介质为10.0mmol/L乳酸-15.0?H5OH、分离电压20.0kV的优化条件下,6min内即可实现地芬诺酯和阿托品的同时分离检测,线性范围分别为5.00~500和2.00~320mg/L;检出限分别为3.0和1.0mg/L。     

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.     

Use of TLC-Densitometric Method for Determination of Valproic Acid in Capsules

Determination of valproic acid in the drug was carried out on the aluminum silica gel 60F₂₅₄ plates and using acetone–water–chloroform–ethanol–ammonia at a volume ratio of 30:1:8:5:11 as the mobile phase, respectively. Two methods of detection of valproic acid were used. The first was a 2% aqueous CuSO₄×5H₂O solution, and the second was a 2′,7′-dichlorofluorescein-aluminum chloride-iron (III) chloride system. The applied TLC-densitometric method is selective, linear, accurate, precise, and robust, regardless of the visualizing reagent used for the determination of valproic acid in Convulex capsules. It has low limits of detection (LOD) and limits of quantification (LOQ), which are equal to 5.8 μg/spot and 17.4 μg/spot using a 2% aqueous CuSO₄×5H₂O solution as visualizing agent and also 0.32 μg/spot and 0.97 μg/spot using a 2′,7′-dichlorofluorescein-aluminum chloride-iron (III) chloride system as visualizing reagent, respectively. The described analytical method can additionally be used to study the identity of valproic acid in a pharmaceutical preparation. The linearity range was found to be 20.00–80.00 μg/spot and 1.00–2.00 μg/spot for valproic acid detected on chromatographic plates using a 2% aqueous CuSO₄×5H₂O solution and the 2′,7′-dichlorofluorescein-aluminum chloride-iron (III) chloride system, respectively. A coefficient of variation that was less than 3% confirms the satisfactory accuracy and precision of the proposed method. The results of the assay of valproic acid equal 96.2% and 97.0% in relation to the label claim that valproic acid fulfill pharmacopoeial requirements. The developed TLC-densitometric method can be suitable for the routine analysis of valproic acid in pharmaceutical formulations. The proposed TLC-densitometry may be an alternative method to the modern high-performance liquid chromatography and square wave voltammetry in the control of above-mentioned substances, and it can be applied when other analytical techniques is not affordable in the laboratory.