大黄酸修饰电极对细胞色素C的催化还原

研究了大黄酸修饰电极的性质及对细胞色素C的催化还原，并研究了其电极应用机理。     

区带毛细管电泳分离测定大黄提取液中游离蒽醌化合物

采用区带毛细管电泳法分离和同时测定大黄提取液中五种蒽醌化合物的含量。毛细管电泳的分离条件为:50 cm×75μm i.d.未涂层石英分光毛细管,分离电压20kV,0.05 mol/L KH2PO4-Na2HPO4(pH=8.2)缓冲溶液,紫外检测波长为254 nm,以氨基苯磺酸为内标。该法简便,快速,分辨率高,重现性好。     

碳糊电极阳极吸附伏安法测定大黄酸

在pH4.2的HAc-NaAc底液中,大黄酸在碳糊电极(CPE)上有一灵敏的吸附氧化峰,峰电位为1.14V(vs.SCE)。该氧化峰的二阶导数峰电流与大黄酸的浓度在8.0×10-9~8.0×10-7mol/L(富集120s)范围内呈良好的线性关系(r=0.998),检出限为2×10-9mol/L(S/N=3,富集180s)。探讨了大黄酸在CPE上的伏安性质和电极反应机理,并将本法应用于中药大黄中的大黄酸的测定,结果良好。     

Total synthesis of rhein and diacerhein via a directed ortho metalation of an aromatic substrate

An efficient total synthesis of rhein and diacerhein has been accomplished by relying on a remarkable regioselective directed ortho metalation (DOM) followed by a one-pot two step addition-cyclization reaction, generating phthalide 5 intermediate efficiently.     

大黄酸玻碳修饰电极对血红蛋白的催化还原

在进行生物电化学分析的过程中 ,血红蛋白 ( Hemoglobin,简称 Hb)是研究的重点物质之一 .由于它的庞大结构及在固体电极上的过电位很大 ,使其在固体电极上的传递速率缓慢 .克服这个困难的方法之一通常是在固体电极上修饰一层物质 ,通常称之为媒介体 ,通过媒介体的传递使得血红蛋白的传递速率得到改善 ,过电位得到显著降低 .从报道的文章[1～ 10 ] 来看 ,这些媒介体大多采用具有氧化还原活性的染料 ,固定媒介体则采用吸附、聚合和电沉积的方法 .吸附是早期修饰电极常用的方法 ,这种Fig.1　 The structure of rhein方法制备的电极往往寿命很…     

高效液相色谱法快速测定大黄中大黄素,大黄酸和芦荟大黄素的研究

研究了高效液相色谱法测定大黄中大黄素、大黄酸和芦荟大黄素。大黄中大黄素、大黄酸和芦荟大黄素用氯仿加热回流提取,提取液蒸干溶剂,以甲醇溶解定容待测。以安捷仑ZORBAX Stable Bound(4.6 mm×50 mm,1.8μm)色谱柱为固定相,质量分数0.1%的H3PO4和甲醇为流动相,梯度洗脱(0 min:VH3PO4∶V甲醇=27∶73;1 min:100%甲醇);在该色谱条件下,大黄素、大黄酸和芦荟大黄素在2.0 min内可达到基线分离;用紫外二极管矩阵检测器检测。方法标准回收率为99.4%~102%,相对标准偏差为1.5%~1.8%。可用于大黄中大黄素、大黄酸和芦荟大黄素的快速分析检测。     

Electrochemical behavior of electrodeposited film derived from rhein and its activity towards myoglobin reduction

The stable electroactive thin film of rhein has been investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Electrochemical impedance spectroscopy of the electrodeposited film derived from rhein indicated the electrode reaction was kinetically controlled in the region of higher frequency, the charge transfer resistance was 2.6×10³ Ω cm² and capacitance value was 13.2 μF cm² . The electrodeposited film derived from rhein exhibited a good electrocatalytic activity for myoglobin (Mb) reduction. In 0.30 mol dm⁻³ H₂SO₄solution, the catalysis currents were proportional to the concentrations of Mb over the range of 1.5×10⁻⁷–1.3×10⁻⁵ mol dm⁻³. The detection limit is 1.0×10⁻⁷ mol dm⁻³ (S/N=3). The relative standard deviation is 4.8% for eight successive determinations of 5.0×10⁻⁷ mol dm⁻³ Mb.     

A Novel Rhein-Functionalized Resin with Application for the Preconcentration of Anthraquinones

Anthraquinones are active components of herbal medicine, and consequently it is necessary to develop a selective, convenient, and green preconcentration method for these compounds. A rhein-functionalized resin was synthesized by a condensation reaction followed by characterization by infrared spectroscopy, transmission electron microscopy, solid carbon-13 nuclear magnetic resonance, and elemental analysis. The rhein-functionalized resin was employed for solid-phase extraction with HPLC-MS for the determination of anthraquinones in the extracts of Polygonum cuspidatum. Emodin, chrysophanol, and physcion were selectively concentrated by a simple absorption and desorption procedure. The results indicated that this new material has application for separating and enriching anthraquinones from herbal medicine, which is significant for pharmaceutical analysis.     

UPLC-MS/MS performing pharmacokinetic and biodistribution studies of rhein

Rhein, an important constituent of Radix et Rhizoma Rhei, has been used to alleviate liver and kidney damage. In this work, plasma pharmacokinetic and biodistribution characteristics of rhein after oral administration was investigated using a rapid and sensitive ultra-performance liquid chromatography coupled to tandem high-definition mass spectrometry (UPLC-MS/MS) method. Mass spectrometry was performed on a Waters Micromass high-definition technology with an electrospray ionization source in positive ion mode. Biosamples were prepared using methanolic precipitation and the separation of rhein was achieved on a UPLC HSS T3 column by linear gradient elution and the total run time was only 4.70 min. Data were analyzed and estimated by compartmental methods using WinNonlin Professional version 5.1. Mean pharmacokinetic parameters following single-dose administration of rhein was consistent with a two-compartmental open model. It was found that rhein was distributed and eliminated rapidly in rats and the biodistribution showed the higher levels were in liver, spleen, kidney, heart, lung and the lower level observed in the muscle, adrenal, and thyroid. It was not discovered in brain and showed that rhein could not cross the blood-brain barrier. Our developed UPLC-MS/MS approach was capable of providing complete pharmacokinetic and biodistribution parameters for rhein when administered orally.     

大黄酸微分脉冲伏安法的研究和应用

利用循环伏安法(CV)、线性扫描伏安法(LSV)、方波伏安法(SWV)和微分脉冲伏安法(DPV)等现代电化学技术,对大黄酸在玻碳电极(GCE)上的电化学氧化还原行为以及电极反应机理进行了研究,同时还建立一种灵敏的测定大黄酸的分析方法.实验结果表明,在 pH 4.6的B R缓冲液中,大黄酸在 0.492 V(vs.SCE)电位处产生灵敏的微分脉冲阴极还原峰, 该还原峰的峰电流值与大黄酸的浓度在 4.0×10-7 mol/L~1.0×10-5 mol/L范围内呈良好的线性关系,最低检测限(D = 3σ/K)为3.9×10-8 mol/L.该法已成功地用于大黄碳酸氢钠片剂和兔血清中大黄酸的测定,结果令人满意,其回收率介于90.0%~100.1% 之间.并进一步对大黄酸在玻碳电极(GCE)上的电化学反应机理进行了探讨.