Electrochemical Behavior of Apigenin at a Glassy Carbon Electrode and its Analytical Application

The electrochemical behavior of the antitumor herbal drug apigenin was studied in 0.1 mol L^?1 B‐R buffer solutions (50% ethanol, pH 3.0) by cyclic voltammetry (CV) at a glassy carbon electrode. In CV, two oxidation peaks (P₁ and P₂) with E_p1 = 1.03V and E_p2 = 1.23 V appeared at a scan rate of 0.05 V s^?1, and a new electroanalytical method for this herbal drug was established according to the oxidation peak P2. The peak currents have a linear relationship with apigenin concentration in a range from 9.0 × 10^?7 to 2.0 × 10^?5 mol L^?1. Using the established method, apigenin in a herbal drug was determined without pre‐separation with satisfactory results. Moreover, the electrode dynamics parameters were also investigated by electrochemical techniques and the possible electrode reaction mechanism was deduced.     

Electrochemical Studies of Anticancer Herbal Drug Sophoridine and Its Interaction with DNA

Sophoridine is a new anticancer herbal drug with remarkable antitumor effect and lower toxicity. In this paper, the electrochemical investigation of sophoridine and its interaction with DNA is reported. In 0.1 mol L^?1 phosphate buffer solution (pH 7.0), sophoridine exhibited excellent electrochemical activity. In the presence of DNA, the peak current of sophoridine decreased in a quantitative fashion and the peak potential shifted to a more positive potential value. It suggests the dominance of intercalative interaction. Importantly, as to the interaction between sophoridine and DNA in solution, characteristic parameters such as the binding stoichiometry and association equilibrium constant according to the Hill model for cooperative binding have been determined.     

抗癌药物8-氮鸟嘌呤在石墨电极上的电化学性质及电分析方法研究

研究了抗癌药物8-氮鸟嘌呤(8-AG)在浸蜡石墨电极上的电化学反应。在HAc-NaAc(pH3.6)缓冲溶液中,8-AG在浸蜡石墨电极上产生一受扩散控制的氧化波,峰电位为1.2V(vs.SCE),峰电流与8-AG浓度在8×10-7～1×10-4mol/L范围内有良好的线性关系,检出限为5×10-7mol/L。研究了电极反应过程,求得了对应的动力学参数,建立了灵敏、快速的8-AG的检测方法。     

盐酸小檗碱-十二烷基苯磺酸钠缔合微粒体系的共振散射光谱研究及其分析应用

在pH 4 .80NaAc HAc缓冲介质中 ,盐酸小檗碱 (BH)与十二烷基苯磺酸钠 (DBS)由于静电引力和疏水作用力形成缔合微粒 ,在 4 70nm处有一共振散射峰。随着DBS浓度增大 ,该峰急剧增强 ,即存在缔合微粒的散射光增强效应 ;345nm处的吸光度减弱 ,即存在缔合微粒的减色效应。研究了共振散射光谱测定BH的影响因素 ,提出了测定 (0 .35～ 4 .4 )× 10 -5mol/L盐酸小檗碱的共振散射光谱新方法 ,用于复方黄连素片剂和针剂样品的测定 ,结果满意     

Electrochemical Determination of the Anticancer Herbal Drug Shikonin at a Nanostructured Poly(hydroxymethylated‐3,4‐ethylenedioxythiophene) Modified Electrode

A simple and sensitive method is described for the electrochemical determination of shikonin, a widely used anti‐tumoral agent, based on its electrochemical oxidation at a nanostructured poly(hydroxymethylated‐3,4‐ethylenedioxy‐thiophene) (PEDOT‐MeOH) electrode, which was fabricated by a facile electropolymerization method. Compared with bare and poly(3,4‐ethylenedioxythiophene) (PEDOT) electrodes, the PEDOT‐MeOH film exhibited a distinctly higher activity for the electrooxidation of shikonin. The PEDOT‐MeOH electrode showed a wide linear response for shikonin in the concentration range from 1.0 nM to 10.0 µM with detection limit of 0.3 nM. Furthermore, the PEDOT‐MeOH electrode displayed high stability, good reproducibility and high sensitivity for the detection of shikonin.     

木犀草素的电化学性质及在其测定中的应用

对木犀草素在单纯水溶液介质中的电化学行为作了研究。结果表明:在pH4.0的B-R缓冲溶液作底液的条件下,得到峰形对称的木犀草素的可逆氧化还原峰。循环伏安法(CV)试验结果表明:其在玻碳电极表面的电极反应受吸附所控制。用积分脉冲伏安法(DPV)研究了氧化峰电流(ipa)与木犀草素浓度(cLu)之间的关系,结果表明:木犀草素浓度在8.0×10-8～8.0×10-6mol.L-1之间呈线性关系,检出限(3S/N)为7.14×10-8mol.L-1,回收率在98.5%～104.0%之间。用线性扫描伏安当(LSV)试验表明:当cLu为4.14×10-5mol.L-1时,ipa达到最大值。据此按公式Q=nFAΓT可算出饱和吸附量ΓT为6.21×10-10mol.cm-2。根据Laviron原理和Langmuir吸附等温式可算出如下电极过程热力学参数,参与氧化还原过程的电子数n=2,电极反应质子数=2,转移系数a=0.90,表现电子传递速率常数ks=2.96s-1,对电极反应的机理也作了简要讨论。     

利培酮的电化学行为及应用研究

采用循环伏安法、线性扫描伏安法、常规脉冲伏安法和恒电位电解法等电化学手段, 详细研究了利培酮在pH 7.07～10.32 B-R缓冲溶液和0.2 mol•L^－1 NaOH溶液中的电化学行为. 研究表明: 在pH 7.07～10.07 B-R缓冲溶液中, 利培酮产生的P₁波为催化氢波. 在pH＝10.32 B-R缓冲溶液中, 利培酮可以产生P₂和P₃两个波. 其中, P₂波为不可逆的单电子还原波, P₃波可以分裂成两个波P_3a和P_3b. P_3a波为P₂波的进一步单电子还原, 而P_3b波则属于催化氢波. 在0.2 mol•L^－1 NaOH溶液中, 利培酮产生的P₄波是一个两电子的不可逆还原波. 另外, 根据P₁波的一阶导数峰电流与利培酮浓度在1.6×10^－5～2.0×10^－6 mol•L^－1 (r＝0.9950)间的线性关系, 建立了利培酮片剂中利培酮含量的测定新方法. 新方法的检出限为1.0×10^－6 mol•L^－1, 回收率在105%～102%之间, 相对标准偏差为0.84%.     

Electrochemical Behavior of an Anti-Viral Drug Valacyclovir at Carbon Paste Electrode and Its Analytical Application

Valacyclovir (VCH) is an antiviral drug, used in the management of viral infections such as herpes simplex and varicella-zoster in humans. It is rapidly converted to acyclovir which has antiviral activity against herpes simplex virus types 1 (HSV-1) and 2 (HSV-2) and Varicella-zoster virus (VZV) both in vitro and in vivo. Electrochemical behavior was studied using cyclic voltammetric method, and the analytical application was studied using differential pulse voltammetric technique. The process on the surface of electrode was found to be irreversible and diffusion controlled. The charge transfer coefficient, heterogeneous rate constant, the number of electron transferred and activation parameters were calculated. Possible free radical reaction mechanism taking place on the surface of electrode was proposed. Calibration plot constructed using differential pulse voltammetric technique and applied for quantitative analysis in pharmaceutical and human urine sample. Limit of detection (LOD) and limit of quantification (LOQ) were calculated and found to be 0.028 and 0.09 μM, respectively. The present work describes the electrochemical behavior of an antiviral drug, VCH and its determination in pharmaceutical samples. The method shows the development of a sensor for selective and sensitive determination of VCH.     

Electrochemical Behavior of Herbal Antitumor Drug Aloe‐Emodin at Carbon‐Coated Nickel Magnetic Nanoparticles Modified Glassy Carbon Electrode

The electrochemical behavior of aloe‐emodin (AE), an important herbal antitumor drug, was investigated at a carbon‐coated nickel magnetic nanoparticles modified glassy carbon electrode (CNN/GCE). A couple of well‐defined redox peaks was obtained. Some electrochemical parameters of AE at a CNN/GCE, such as the charge number, exchange current density, standard heterogeneous rate constant, were measured. The square wave voltammetry (SWV) response of AE was linear with the concentration over two concentration intervals viz. 6.24×10^?9?1.13×10^?6 M and 1.13×10^?6?1.23×10^?5 M, with a detection limit of 2.08 nM. A fast, simple and sensitive detection and analysis of AE was developed.     

Electrochemical Behaviour of the Anticancer Dacarbazine‐Cu2+ Complex and Its Analytical Applications

Electrochemical reduction of the dacarbazine‐Cu²⁺ complex was investigated using cyclic voltammetry and square wave voltammetry at a hanging mercury drop electrode. The reduction of the dacarbazine‐Cu²⁺ complex is irreversible. A reduction mechanism is proposed comprising a one‐electron reduction of the Cu²⁺ directly within the complex. The sharp peak of the adsorbed dacarbazine‐Cu²⁺ complex associated with an effective interfacial accumulation facilitates the determination of the anticancer drug dacarbazine in pharmaceutical formulations and biological fluids. Detection limits for dacarbazine of 6.12×10^?10 M, 1.57×10^?10 M and 1.97×10^?9 M were achieved for the determination of the drug in vial, human urine and serum, respectively.     

Electrochemical Oxidation of Berberine and of Its Oxidation Products at a Glassy Carbon Electrode

The electrochemical behavior of berberine, an isoquinoline plant alkaloid with a wide spectrum of physiological effects, was studied at a glassy carbon electrode using cyclic, differential pulse and square‐wave voltammetry. The oxidation of berberine is a quasireversible, diffusion‐controlled process and occurred in a cascade mechanism with the formation of several oxidation products. The diffusion coefficient of berberine was calculated from cyclic voltammetry studies to be D=1.69×10^?6 cm² s^?1. The oxidation process of berberine is also pH dependent and the number of electrons and protons transferred was determined using differential pulse voltammetry. The formation of several oxidation products that adsorbed at the glassy carbon electrode surface was observed and their electrochemical behavior characterized. A mechanism for the oxidation of berberine at a glassy carbon electrode was proposed.     

甘草酸的电化学行为研究

用循环伏安法、单扫描示波极谱法研究了甘草酸（ｇｌｙｃｙｒｒｈｉｚｉｃ，ＧＡ）在汞电极上的电化学行为及反应机理．证明甘草酸在ｐＨ＝４～１２的缓冲溶液（Ｈ３ＢＯ３＋Ｈ３ＰＯ４＋乙酸＋ＮａＯＨ）中有吸附峰，且示波极谱导数峰值与甘草酸浓度在８．３×１０－５～１．２×１０－６ｍｏｌ／Ｌ范围内成正比，使用悬汞电极（ＨＭＤＥ）线性扫描伏安法可使检测下限达２．４×１０－６ｍｏｌ／Ｌ．根据实验结果首次提出了甘草酸在汞电极上的反应机理．该机理同时被紫外光谱证明，得到合理解释     

Electrochemical Study of Interaction Between Clozapine and DNA and Its Analytical Application

Abstract

The interaction between clozapine (CLZ) as an orally administrated antipsychotic drug with double stranded calf thymus DNA (dsDNA) was investigated at electrode surface using differential pulse voltammetry (DPV). Activated carbon paste electrode (CPE) was modified with dsDNA and used for monitoring the changes of the characteristics peak of CLZ in 0.05 M acetate buffer (pH 4.3). The adsorptive stripping voltammetry on dsDNA‐modified carbon paste electrode (dsDNA‐CPE) was used for determination of very low concentration of CLZ. Under optimal conditions, the oxidation peak current is proportional to CLZ concentration in the range of 7×10^?9?1.2×10^?6 mol l^?1 with a detection limit of 1.5×10^?9 mol l^?1 for 180 s accumulation time by DPV. The proposed dsDNA‐CPE was successfully used for determination of CLZ in human serum samples with recovery of 97.0±2.5%.     

细胞色素C在阴离子修饰的盐桥支撑双层类脂膜上的电化学行为及其应用

采用循环伏安法研究了细胞色素C在月桂酸阴离子修饰的盐桥支撑双层类脂膜上的氧化还原反应;对盐桥支撑双层类脂膜的特性、细胞色素C的电化学反应动力学以及有关影响细胞色素C循环伏安行为各种因素进行了详细探讨;并对用该双层类脂膜体系电化学测定细胞色素C进行了初步尝试。     

喜树碱的电还原特性及应用研究

The voltammetric behavior of camptothecin （CPT） in Britton-Robinson （B-R） buffer solutions （pH 2.09-9.07） was studied by the means of linear sweep voltammetry （LSV）, cyclic voltarnmetry （CV） and normal pulse voltammetry （NPV） at a hanging mercury drop electrode. In different pH range of B-R buffer solutions, CPT could cause three reduction waves. In B-R buffer solutions （pH 2.09-5.46）, wave P1 yielded by CPT was a two-electron wave. Between pH 6.01 and 9.07, CPT could yield two reduction waves P2 and P3. In addition, the pure CPT obtained from camptotheca acumina grown only in China was determined by NPV, and a linear response was observed in the range of 2.0 × 10^-3-4.0 × 10^-2 mmol·L^-1 with a 0.9991 correlation coefficient and a 8.0 × 1^-4 mmol·L^-1 detection limit for CPT.     

抗癌新药染料木素的电化学行为及其应用研究

研究了新型抗癌药物染料木素在pH=1～12水溶液中的极谱行为。在不同pH范围内得到了染料木素的四个还原波。研究证实在ph＜5的条件下所获得的P1波及5＜pH＜10介质中获得的P2波为染料木素中性分子的两电子,单质子及其电离形成一价阴离子的两电子,单质子不可逆吸附还原波。在pH＜6的条件下所获得的P3波属于染料木素解离形成阴离子的不可逆强吸附前波,而P4波则属于染料木素在碱性介质中解离形成高价阴离子的不可逆吸附还原波。此外通过邻苯三酚自氧化产生活性氧自由基的再还原,对染料木素清除活性氧自由基的能力进行了研究,从电化学的角度对其药理机制进行了阐述。     

小檗碱的药物代谢动力学

小檗碱是中药三棵针的主要有效成分之一，为了研究小檗碱的药物代谢动力学，本文采用胶束增敏荧光法对小檗碱在兔体内的血药浓度进行２４ｈ监测，求出毓药物代谢动力学参数，结果表明小檗碱在动物体内的Ｋａ为１．６３７ｈ＾－１，ｔ１／２（α） ０．３８６９ｈ，ｔ１／２（β）为６．７６ｈ，Ｋ２１为０．１５５３ｈ＾－１，Ｋ１２ｏ ０．０３８４ｈ＾－１，ＡＵＣ为２１１。９４μｇ．ｈ／ｍｌ。     

硒代蛋氨酸的电化学行为及其定量分析

本文采用循环伏安法(CV)研究了硒代蛋氨酸(SeMet)在银电极表面的电化学行为。实验发现,在0.03mol/L的硼砂 NaOH(pH9.5)介质中,于+0.30V(vs.SCE)电位下进行吸附,在-0.62V和-0.68V处获得一对氧化还原峰。探讨了SeMet在银电极表面的电极反应机理,并建立其定量分析方法。方法线性范围为2.0×10-11～8.0×10-9mol/L,检出限为4.0×10-12mol/L。该方法用于谷物样品中SeMet含量的测定,结果满意。     

Study on the Electrochemical Properties of Salvianic Acid A Sodium and its Analytical Application

The electrochemical behavior of salvianic acid A sodium (SAS), a main active content in Chinese herbal medicine (CHM), was studied for the first time by cyclic voltammetry (CV). A new electroanalytical method of SAS was erected using differential pulse voltammetric (DPV) technique. In pH 3.3 britton‐robinson (B‐R) buffer solution, the medicine showed a pair of redox peaks driven by adsorption. The electrode process involved two electrons and two protons transformation with apparent rate constant (ks) of 2.85 s^?1 and transfer coefficient (α) of 0.81. Based on understanding the electrochemical process of SAS at the glassy carbon electrode (GCE), analysis of SAS can be realized. The oxidation peak currents showed linear with the concentrations of SAS in the range of 5.45 × 10^?8 to 1.09 × 10^?5 M. The limit of detection was 5.45 × 10^?8 M. The proposed method has high sensitivity, wide linear range, and was successfully applied to quantitative determination of the SAS in Rukuaixiao Tablets.     

荷叶碱的电化学行为研究及分析应用

本文详细研究了荷叶碱在玻碳电极上的电化学氧化行为。在pH=5.5的B-R缓冲溶液中,用微分脉冲伏安法测定,荷叶碱于＋0.87V（vs.SCE）左右产生一个灵敏的氧化峰,峰电流与荷叶碱的浓度在0.25-30.0μg／mL的范围内呈良好线性关系,检出限为0.05μg／mL。该方法用于荷叶中总生物碱含量的测定,平均回收率为91.5％。此外对荷叶碱的电化学氧化机理进行了探讨。