Two inclusion compounds of guanylthiourea and 1,3,5-thiadiazole-5-amido-2-carbamate

In the crystal structure of [(n-C₄H₉)₄N]⁺·[NH₂(C₂N₂S)NHCOO^?]·NH₂CSNC(NH₂)₂ (1), guanylthiourea molecules and 1,3,5-thiadiazole-5-amido-2-carbamate ions are joined together by intermolecular N–H…O, N–H…N, and weak N–H…S hydrogen bonds to generate stacked host layers corresponding to the (110) family of planes, between which the tetra-n-butylammonium guest cations are orderly arranged in a sandwich-like manner. In the crystal structure of [(n-C₃H₇)₄N]⁺·[NH₂(C₂N₂S)NHCOO^?]·NH₂CSNC(NH₂)₂·H₂O (2), the tetrapropyl ammonium cations are stacked within channels each composed of hydrogen bonded ribbons of guanylthiourea molecules, 1,3,5-thiadiazole-5-amido-2-carbamate ions and water molecules.     

Determination of asperosaponin VI in dog plasma by high-performance liquid chromatography-tandem mass spectrometry and its application to a pilot pharmacokinetic study

A sensitive and rapid liquid chromatography–tandem mass spectrometry (LC‐MS/MS) method has been developed and validated for the determination of asperosaponin VI in beagle dog plasma using glycyrrhizic acid as the internal standard (IS). Plasma samples were simply pretreated with methanol for deproteinization. Chromatographic separation was performed on a Hedera ODS‐2 column using mobile phase of methanol–10 mm ammonium acetate buffer solution containing 0.05% acetic acid (71:29, v/v) at a flow rate of 0.38 mL/min. Asperosaponin VI and the IS were eluted at 2.8 and 1.9 min, respectively, ionized in negative ion mode, and then detected by multiple reaction monitoring. The detection used the transitions of the deprotonated molecules at m/z 927.5 → 603.4 for asperosaponin VI and m/z 821.4 → 645.4 for glycyrrhizic acid (IS). The assay was linear over the concentration range of 0.15–700 ng/mL and was successfully applied to a pilot pharmacokinetic study in beagle dogs. Copyright © 2011 John Wiley & Sons, Ltd.     

表面蒸气溶胶-凝胶Al2O3薄膜电极上肌红蛋白的直接电化学研究

本文利用表面蒸气溶胶-凝胶沉积与层层组装技术相结合,成功制备了溶胶-凝胶三氧化二铝(SG-Al2O3)/肌红蛋白(Mb)层层组装薄膜修饰电极({SG-Al2O3/Mb}n)。通过实验确定了最优组装方式PG/PD-DA/{SG-Al2O3/Mb(pH 5.0)}n以及在表面蒸气溶胶-凝胶沉积过程中的最佳涂布水量2μL。考察了该薄膜修饰电极的循环伏安性质。实验表明:在pH 7.0缓冲溶液中,薄膜中的Mb在-0.34 V出现了一对可逆性良好的还原氧化峰,这是血红素辅基的电活性中心Fe(III)/Fe(II)氧化还原电对的特征峰,随着缓冲溶液pH值的增长,峰电位发生负移,式量电位E°’与pH值呈直线关系,其斜率为–42.4 mV/pH,随着扫描速度的增大,峰电流增大,且电流与扫描速度的平方根成正比。     

基于分离粒子随机扩散理论的色谱模拟

为了对扩散分子的轨迹实施动态追踪与模拟, 深入理解分子扩散对色谱动力学的影响, 本文利用微尺度受限空间随机行走的模拟方法对色谱填充柱中的分子扩散过程进行了模拟. 重点考察了固定相的填充率、固定相的形状和柱长对色谱动力学行为的影响. 模拟结果表明短柱和大填充率具有较高的柱效; 在相同的密堆排列下, 固定相形状对分子扩散过程影响微弱; 待分离粒子的运动表现出微尺度空间限域的扩散特征, 但粒子的流动行为会随外部压力的增大而增加. 本论文提出的模拟方法对于发展高效能色谱, 开发新型分离技术等具有参考意义.     

ZnSe掺Cu与Zn空位缺陷的稳定性、电子结构与光学性质

采用基于密度泛函理论框架下的第一性原理平面波超软雁势方法, 对ZnSe闪锌矿结构本体、掺入p型杂质Cu(Zn_0.875Cu_0.125Se)及Zn空位(Zn_0.875Se)超晶胞进行结构优化处理. 计算并详细分析了缺陷体系的形成能和三种体系下ZnSe材料的态密度、能带结构、集居数、介电和吸收光谱. 结果表明: 在Zn空位与Cu掺杂ZnSe体系中, 由于空位及杂质能级的引入, 禁带宽度有所减小, 吸收光谱产生红移; 单空位缺陷结构不易形成, Zn_0.875Se结构不稳定, Cu掺杂ZnSe结构相对更稳定.     

Highly Enantioselective Iridium‐Catalyzed Hydrogenation of α,β‐Unsaturated Esters

α,β‐Unsaturated esters have been employed as substrates in iridium‐catalyzed asymmetric hydrogenation. Full conversions and good to excellent enantioselectivities (up to 99 % ee) were obtained for a broad range of substrates with both aromatic‐ and aliphatic substituents on the prochiral carbon. The hydrogenated products are highly useful as building blocks in the synthesis of a variety of natural products and pharmaceuticals.     

Synthesis and antitumor activity of 1-acetyl-3-(4-phenyl)-4,5-dihydro-2-pyrazoline-5-phenylursolate and 4-chalcone ursolate derivatives

New 4-chalcone ursolate and 1-acetyl-3-(4-phenyl)-4,5-dihydro-2-pyrazoline-5-phenyl ursolate derivatives were synthesized by esterification of UA and chalcone or pyrazoline. The compounds were structurally confirmed by IR, ¹H NMR, ¹³C NMR, and HR-MS spectroscopy. The cytotoxicity of ten derivatives was evaluated against A549, SKOV3, and HepG2 cell lines by MTT assay. The result showed that several compounds were more potent than UA against A549 and SKOV3 cells; however, none of them were more potent than UA against HepG2.     

Design, synthesis and primary activity of thiomorpholine derivatives as DPP-IV inhibitors

Thirteen thiomorpholine-bearing compounds were designed and synthesized as dipeptidyl peptidase IV（DPP-IV） inhibitors, with natural and non-natural L-amino acids as the starting materials.Their structures were characterized by ¹H NMR,¹³C NMR and HR-MS.The target compounds were screened for the DPP-IV inhibition,and the preliminary SAR result was obtained.Particularly, compounds 4c,4d and 4f with good DPP-IV inhibition in vitro were further evaluated through a mouse oral glucose tolerance test （OGTT）.The preliminary result showed the potential value for further studies on those thiomorpholine-bearing compounds as DPP-IV inhibitors.     

Homogenous synthesis of 3-allyloxy-2-hydroxypropyl-cellulose in NaOH/urea aqueous system

3-Allyloxy-2-hydroxypropylcelluloses (AHP-celluloses), reactive unsaturated cellulose derivatives, were homogeneously synthesized by the reaction of cellulose with allyl glycidyl ether (AGE) in NaOH/urea aqueous solution. Water-soluble AHP-celluloses with DS_NMR = 0.32–0.67 were prepared from microcrystalline cellulose. The degree of substitution (DS) of AHP-celluloses could be controlled by varying the molar ratio of AGE and NaOH to AGU and the reaction conditions. The structure of AHP-cellulose samples were characterized by means of FT-IR, NMR spectroscopy and size exclusion chromatography. The cellulose ether shows thermoreversible flocculation. Bromination reactions were carried out as subsequent functionalization both to illustrate the reactivity of the allyl function and to determine the DS values.     

高效液相色谱-串联质谱法检测奶中克拉维酸残留

采用高效液相色谱-串联质谱(HPLC-MS/MS)建立了克拉维酸在奶中的残留检测方法。2 g样品经乙醇沉淀蛋白质后,转入鸡心瓶中旋转蒸发浓缩至0.5 mL左右,用乙酸铵定容,净化后检测。流动相为乙腈和0.1%甲酸水,梯度洗脱,经Luna 5u C8色谱柱分离,采用电喷雾电离,多反应监测负离子模式对克拉维酸进行定量分析。采用基质匹配法对奶中克拉维酸的含量进行标准校正,在克拉维酸含量为10～400 μg/kg范围内呈现良好的线性关系,相关系数大于0.999;奶中加标样品的检出限(LOD,按信噪比(S/N)≥3计)为10 μg/kg,定量限(LOQ, S/N≥10)为20 μg/kg。在定量限、1/2最高残留限量、最高残留限量、2倍最高残留限量添加水平下,奶中克拉维酸的平均回收率为80.00%～91.25%,相对标准偏差为5.60%～8.77%。该方法可用于奶中克拉维酸残留的分析检测。