Electrocatalytic activities of Nafion/CdSe/Self-doped polyaniline composites to dopamine,uric acid,and ascorbic acid

Composites of Nafion, COOH-capped CdSe, and self-doped polyaniline (SPAN) were used to prepare novel chemical modified glassy carbon electrodes (Nafion/CdSe/SPAN/GCE). The electrocatalytic activities of the modified GCE to the redox reactions of dopamine (DA), uric acid (UA), and ascorbic acid (AA) were investigated by cyclic voltammetry (CV). CV curves revealed that the electrocatalytic activities of Nafion/CdSe/SPAN/GCE to oxidations of the analytes in solution of pH 7 were in the order of DA?>?UA?>?AA. This order was consistent with the strong-to-low extent of interactions between the modified GCE and the analytes. These interactions were consistent with the observations that the oxidation rate of DA followed a diffusion-controlled process whereas that of UA followed a surface adsorption-controlled process. The composites of casting at higher pH levels were found to exhibit better CdSe and SPAN dispersions in films and higher electrocatalytic activities. CdSe and SPAN exhibited insignificant synergistic effects on the oxidations of DA when cast from Nafion solutions of both low and high pHs whereas CdSe and SPAN exhibited much synergistic effects on the oxidations of UA when cast from the Nafion solution of high pH at 12.     

Inclusion complexes of a nucleotide analogue with hydroxypropyl-beta-cyclodextrin

Bis(tbutyl-S-acyl-2-thioethyl)-AraCMP (UA911) is a mononucleotide prodrug developed to overcome some of the cellular resistance to cytotoxic deoxynucleosides analogues. Its use for in vivo studies is limited due to its poor solubility in water. Thus, 2-hydroxypropyl-beta-cyclodextrin (HP-β-CD) was proposed to solubilize UA911 in water, in order to obtain concentrations needed for in vivo experiments. A molar ratio of HP-β-CD: UA911 of 3:1 was sufficient to obtain complete solubilization of the prodrug. The corresponding inclusion complex was characterized by differential scanning calorimetry and ¹H NMR spectroscopy study provided a definitive proof of the formation of the inclusion complex. The complex retained its cytotoxic activity as shown by in vitro cell survival assays on murine leukemia cells, and was evaluated in vivo. HP-β-CD is therefore suitable for the preparation of adequate solutions for the study of the antitumoral activity of nucleotide prodrugs such as UA911.     

Cytotoxic activity and DNA binding of naphthalimide derivatives with amino acid and dichloroacetamide functionalizations

A series of novel naphthalimide derivatives modified by amino acids and their dichloroacetamide derivatives at the 3-position have been synthesized. Their cytotoxic activities were preliminarily evaluated against Hela, A549 and K562 cells, which showed that the length of the side chains of the amino acids influenced the cytotoxic activities. Moreover, compound 7d showed a very good cytotoxic activity against A549 cells with an IC50 value of 4.78 mmol Là1. Furthermore, the UV–vis, fluorescence,and circular dichroism(CD) spectroscopies and thermal denaturation experiment indicated that compounds 6a, 6d and 7a, 7d, as DNA intercalators, exhibited binding affinities with calf-thymus DNA(Ct-DNA).     

多巴胺在聚钙羧酸膜修饰碳糊电极上的电催化及与尿酸的同时测定

采用循环伏安法(CV)制备了聚钙羧酸(PCCA)膜修饰的碳糊电极(CPE)。考察了电极对多巴胺(DA)、尿酸(UA)的电氧化催化性能。结果显示,聚钙羧酸膜修饰碳糊电极(PCCA/CPE)对DA有良好的电催化效果,DA呈现出一对准可逆的氧化还原峰,氧化峰电流与DA浓度在3.0×10-7～1.0×10-4mol/L范围内呈线性关系,检出限为1×10-7mol/L(S/N=3)。使用微分脉冲伏安法(DPV),DA和UA在PCCA/CPE上的氧化峰能完全分离(ΔEp=192 mV),且峰电流与浓度均呈现良好的线性关系,可实现对DA和UA的同时测定。实验还进行了实际样品测定。     

双-β-咔啉衍生物的设计、合成及抗肿瘤活性

以去氢骆驼蓬碱为原料, 经过脱甲基、 烷基化等步骤, 合成了一系列双-β-咔啉衍生物. 目标化合物均经核磁共振谱(NMR)和质谱(MS)进行结构确证. 以顺铂为阳性对照药, 采用四甲基偶氮唑盐(MTT)法考察了目标化合物体外抗肿瘤(Bel-7402, 786-0, BGC-823, A375, 769-P和MCF7等6株细胞)活性. 结果表明, 化合物4g和4o与阳性对照药相比具有良好的抗肿瘤活性, 其半抑制浓度(IC₅₀)值均小于10 μmol/L. 初步构效关系研究表明, 当桥链亚甲基数目为8~10, β-咔啉环上9-丁基或9-异丁基取代时, 化合物的抗肿瘤活性较强.     

Two novel alkaloids from the stem of Saprosma hainanense and their cytotoxic activities in vitro

Two novel alkaloids, saprosmine A (1) and saprosmine B (2), were isolated from the stem of Saprosma hainanense MERR., along with five known alkaloids: marcanine A (3); cleistopholine (4); 4-methoxycarbonyl-5,10-benzogquinolinequinone (5); liriodenine (6); and quinoline (7). The chemical structures were established on the basis of extensive spectroscopic (IR, 1D-NMR, 2D-NMR, MS) data analysis and by comparison with spectroscopic data reported in the literature. Compounds 1 to 6 were evaluated for in vitro cytotoxic activities against the SPC-A-1 (human lung cancer), BEL-7402 (human hepatocellular carcinoma), SGC-7901 (human gastric cancer), and K-562 (human myelogenous leukaemia) cancer cell lines. Compounds 1 and 2 exhibited weak cytotoxic activities against K-562 cells. Compounds 3 and 5 showed cytotoxic activities against all four cancer cell lines.     

双-β-咔啉衍生物的设计、合成及抗肿瘤活性

以去氢骆驼蓬碱为原料,经过脱甲基、烷基化等步骤,合成了一系列双-β-咔啉衍生物.目标化合物均经核磁共振谱(NMR)和质谱(MS)进行结构确证.以顺铂为阳性对照药,采用四甲基偶氮唑盐(MTT)法考察了目标化合物体外抗肿瘤(Bel-7402,786-0,BGC-823,A375,769-P和MCF7等6株细胞)活性.结果表明,化合物4g和4o与阳性对照药相比具有良好的抗肿瘤活性,其半抑制浓度(IC_(50))值均小于10μmol/L.初步构效关系研究表明,当桥链亚甲基数目为8~10,β-咔啉环上9-丁基或9-异丁基取代时,化合物的抗肿瘤活性较强.     

柠檬酸修饰电极对抗坏血酸、多巴胺和尿酸的同时检测

研究柠檬酸(CA)修饰玻碳电极(CA/GC)在抗坏血酸(AA)、多巴胺(DA)和尿酸(UA)混合体系中的循环伏安(CV)行为.结果表明,AA、DA和UA在CA/GC电极上氧化峰电流增大,且三者氧化峰电位明显分离(ΔEp(DA,AA)=170 mV,ΔEp(DA,UA)=130 mV,ΔEp(AA,UA)=300 mV).据此,可同时检测AA、DA和UA.在优化的实验条件下,AA、DA和UA的氧化峰电流与其浓度分别在2.0×10-6～1.5×10-3mol.L-1,6.0×10-7～1.0×10-3mol.L-1和6.0×10-7～1.0×10-3mol.L-1范围内呈线性关系.该电极重现性好,可用于盐酸多巴胺针剂DA、VC片剂AA及人体尿液UA的测定.     

Ozonolysis of uric acid at the air/water interface

Uric acid (UA) epoxide, peroxide, and ozonide species produced in aqueous UA microdroplets exposed to O(3)(g) are detected by online mass spectrometry within approximately 1 ms. UA conversions are independent of its initial concentration below approximately 0.1 mM and are unaffected by addition of excess H(2)O(2) or t-butanol. UA reactivity increases approximately 380 times from pH 4 to 7, which is at variance with the pH-independent rates reported for the UA + O(3)(aq) reaction in bulk water. At pH approximately 7, UA and ascorbic acid (AH(2)) microdroplets react with O(3)(g) at similar rates, although UA is approximately 40 times more reactive than AH(2) toward O(3)(aq) in bulk water. Only the UA epoxide, plus traces of UA peroxide, are formed upon mixing UA(aq) and O(3)(aq) solutions. We infer that the gas-liquid ozonolysis of UA proceeds in an interfacial aqueous medium quite distinct from bulk water. Thus, UA, a component of the pulmonary epithelial lining fluid that scavenges atmospheric O(3)(g) into less deleterious species (similar to AH(2)), is rendered inactive below pH approximately 5. The potential implications of these findings on synergistic health effects between tropospheric ozone and acidic particulates are briefly analyzed.     

One new bufadienolide biotransformed from cinobufagin by Cunninghamella elegans

Cunninghamella elegans has been employed for the biotransformation of cinobufagin （1） to afford one metabolites. The structure of the transformation product has been characterized as 7β,12β-dihydroxylcinobufagin （2）. Product 2 is a new compound. In vitro cytotoxic activities of the biotransformation product and the substrate-cinobufagin have been assayed against HeLa; they all showed cytotoxic activities.     

Paeonenoides D and E: Two New Nortriterpenoids from Paeonia lactiflora and Their Inhibitory Activities on NO Production

Two new nortriterpenoids, paeonenoides D and E ( 1 and 2 , resp.), together with seven known compounds, were isolated from the roots of Paeonia lactiflora. Their structures were elucidated on the basis of spectroscopic evidence. Compounds 1 – 7 were screened for inhibitory effects against NO production in LPS‐induced RAW246.7 macrophages and for cytotoxic activities against HL‐60, Hep‐G2, and SK‐OV‐3 cell lines. Compounds 1 – 3 and 5 – 7 exhibited inhibitory activities with IC₅₀ values in the range of 9.6–32.2 μM . Triterpenoids with an epoxide ring and a free COOH function, 1 – 3 , showed effectively increased activities compared with other pentacyclic triterpenoids. Compounds 1 – 6 showed significant cytotoxic activities against the Hep‐G2 cell line and modest cytotoxic activities against HL‐60 and SK‐OV‐3 cell lines.     

Synthesis and antitumor activities of novel bis-quinazolin-4(3H)-ones

With the aim of obtaining new antitumor agents, a series of bis-quinazolin-4(3H)-ones ( 3a-3 f ) were designed and synthesized. These products contain 4-oxo-1,2,3,4-tetrahydro-quinazoline and 3H-quinazolin-4-one moieties linked together via a propyl chain. Cytotoxic activities of 3a-3 f were evaluated against lung adenocarcinoma (A549), breast carcinoma (MCF-7) and ovarian cancer (SKOV3) cell lines using MTT method. Cisplatin was used as a positive control. Among the tested compounds 3a , 3b , and 3e showed the best cytotoxic activities against all cancerous cell lines with IC₅₀ values even less than cisplatin. Compounds 3d and 3f also showed desirable cytotoxic activities especially against A549 and MCF-7.     

Hyperisampsins N and O,two new benzoylated phloroglucinol derivatives from Hypericum sampsonii

Twenty-one benzoylated phloroglucinol derivatives bearing homoadamantyl frameworks were isolated from the aerial parts of Hypericum sampsonii, including two new ones named hyperisampsins N and O (1 and 2). The structures of 1 and 2 were elucidated by extensive NMR and mass spectrometric analyses. Their absolute configurations were further determined by using TDDFT ECD calculations. Compounds 2, 7, and 8 were evaluated for their cytotoxic activities against five human cancer cell lines, of which, 2 and 8 exhibited significant cytotoxic activities toward HL-60 cell and moderate activities against others cell lines.     

Lignans and Triterpenes from the Root of Pseuderanthemum carruthersii var. atropurpureum

Two new lignans, pseuderesinol (1), pseuderanoside (2) and a new triterpene, pseuderanic acid (3) were isolated from the dried root of Pseuderanthemum carruthersii (SEEM.) GUILL. var. atropurpureum (BULL.) FOSB. (Acanthaceae), together with ten known compounds, including five lignans, (+)-eudesmin (4), (+)-magnolin (5), (+)-syringaresinol (6), (+)-episyringaresinol (7), (+)-1-hydroxysyringaresinol (8) and five triterpenes, squalene (9), oleanolic acid (10), lupeol (11), betulin (12), betulinic acid (13). Their chemical structures were elucidated by 1D- and 2D-NMR, computational quantum chemistry, as well as high resolution-electrospray ionization (HR-ESI)-MS spectroscopic analysis. The acetylcholinesterase inhibition and cytotoxic activities against HeLa and MCF-7 cancer cell lines were evaluated on some purified compounds at the concentration of 100?μg/mL. Pseuderesinol (1) and magnolin (5) exhibited moderate cytotoxic activities against the MCF-7 cancer cell line.     

Synthesis and bioactivity of beta-carboline derivatives

The beta-carboline alkaloids possess a wide diversity of important biochemical effects and pharmacological properties. A series of beta-carboline derivatives were synthesized from L-tryptophan through the Pictet-Spengler reaction and oxidation of K2Cr2O7 by a sequential one-pot synthesis method. In vitro anti-bacterial, insecticidal, and cytotoxic activities of all synthesized compounds were investigated by the tablet diffusion, leaf disc, and MTT methods, respectively. Some of the compounds (1-1, 1-2, 1-3 and 1-12) exhibited obvious anti-bacterial effects and some (1-3) had significant cytotoxic activities against tumor cells 3LL, MCF-7, BGC-823 and QGY-7701, with IC50 values of 7.79, 5.75, 3.53 and 4.02 microg/mL, respectively. No insecticidal activity against third stage instar larvae of Mythimna separata Walker were observed under the tested concentration.     

Detection of Uric Acid in the Presence of Dopamine and High Concentration of Ascorbic Acid Using PDDA Modified Graphite Electrode

The properties of graphite electrode (Gr) modified with poly(diallyl dimethyl ammonium chloride) (PDDA) for the detection of uric acid (UA) in the presence of dopamine (DA) and high concentration of ascorbic acid (AA) have been investigated by cyclic voltammetry, differential pulse voltammetry and chronoamperometry. The polymer modified graphite electrode was prepared by a very simple method just by immersing the graphite electrode in PDDA solution for 20 minutes. The PDDA/Gr modified electrode displayed excellent electrocatalytic activity towards the oxidation of UA, DA and AA compared to that at the bare graphite electrode. The electrochemical oxidation signals of UA, DA and AA are well resolved into three distinct peaks with peak potential separations of 220 mV, 168 mV and 387 mV between AA‐DA, DA‐UA and AA‐UA respectively in cyclic voltammetry studies and the corresponding peak potential separations are 230 mV, 130 mV and 354 mV respectively in differential pulse voltammetry. The lowest detection limits obtained for UA, DA and AA were 1×10^?7 M, 2×10^?7 M and 800×10^?9 M respectively. The PDDA/Gr electrode efficiently eliminated the interference of DA and a high concentration of AA in the determination of UA with good selectivity, sensitivity and reproducibility. The modified electrode was also successfully applied for simultaneous determination of UA, DA and AA in their ternary mixture.     

New Polyketides Isolated from Botryosphaeria australis Strain ZJ12‐1A

Four new polyketides, botryosphaerones A–D ( 1 – 4 , resp.), were obtained from the fermentation culture of Botryosphaeria australis strain ZJ12‐1A, together with four known compounds, O‐methylasparvenone ( 5 ), 6‐ethyl‐2,7‐dimethoxyjuglon ( 6 ) and its monoacetyl derivative 7 , and O‐methylaspmenone ( 8 ). Their structures were elucidated by spectroscopic analyses, including 1D‐ and 2D‐NMR experiments, and HR‐Q‐TOF mass spectrometry, and by comparison with reported data. All compounds were evaluated for their cytotoxic and antimicrobial activities in vitro. Only compounds 6 and 7 showed cytotoxic and antimicrobial activities, as already reported.     

聚(3-氨基-5-巯基-1,2,4-三唑)/多壁碳纳米管修饰的玻碳电极同时检测尿酸、黄嘌呤与次黄嘌呤

采用滴涂法得到多壁碳纳米管(MWCNTs)修饰的玻碳电极(GCE),通过电沉积方法将3-氨基-5-巯基-1,2,4-三唑(TA)沉积在MWCNTs/GCE表面,制备了聚(3-氨基-5-巯基-1,2,4-三唑)/多壁碳纳米管修饰电极(p TA/MWCNTs/GCE)。采用循环伏安法(CV)和示差脉冲伏安法(DPV),研究了尿酸(UA)、黄嘌呤(XA)和次黄嘌呤(HX)在该修饰电极上的电化学行为。结果表明,该修饰电极对UA、XA和HX均有较好的电催化活性作用,能实现对3种物质的同时测定。UA、XA和HX在该修饰电极上的线性范围分别为9.0~739.0、2.0~259.0、1.0~353.0μmol/L;检出限分别为0.67、0.17、0.33μmol/L。该修饰电极已成功用于尿液和血清实际样品中UA、XA和HX的同时测定,回收率为98.8%~105.5%。     

Differential Pulse Voltammetric Determination of Uric Acid on Carbon‐Coated Iron Nanoparticle Modified Glassy Carbon Electrodes

A carbon‐coated iron nanoparticles (CIN, a new style fullerence related nanomaterial) modified glassy carbon electrode (CIN/GCE) has been developed for the determination of uric acid (UA). Electrochemical behaviors of UA on CIN/GCE were explored by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). It was found that the voltammetric response of UA on CIN/GC was enhanced dramatically because of the strong accumulation effect of CIN and the large working area of the CIN/GC electrode. The parameters including the pH of supporting electrolyte, accumulation potential and time, that govern the analytical performance of UA have been studied and optimized. The DPV signal of UA on CIN/GCE increased linearly with its concentration in the range from 5.0×10^?7 to 2.0×10^?5 M, with a detection limit of 1.5×10^?7 M (S/N=3). The CIN/GCE was used for the determination of UA in samples with satisfactory results. The proposed CIN/GCE electrochemical sensing platform holds great promise for simple, rapid, and accurate detection of UA.     

Inhibitory Effect of Ursolic Acid on the Migration and Invasion of Doxorubicin-Resistant Breast Cancer

The cause of death in most breast cancer patients is disease metastasis and the occurrence of multidrug resistance (MDR). Ornithine decarboxylase (ODC), which is involved into multiple pathways, is closely related to carcinogenesis and development. Ursolic acid (UA), a natural triterpenoid compound, has been shown to reverse the MDR characteristics of tumor cells. However, the effect of UA on the invasion and metastasis of tumor cells with MDR is not known. Therefore, we investigated the effects of UA on invasion and metastasis, ODC-related polyamine metabolism, and MAPK-Erk-VEGF/MMP-9 signaling pathways in a doxorubicin-resistant breast cancer cell (MCF-7/ADR) model. The obtained results showed that UA significantly inhibited the adhesion and migration of MCF-7/ADR cells, and had higher affinities with key active cavity residues of ODC compared to the known inhibitor di-fluoro-methyl-ornithine (DFMO). UA could downregulate ODC, phosphorylated Erk (P-Erk), VEGF, and matrix metalloproteinase-9 (MMP-9) activity. Meanwhile, UA significantly reduced the content of metabolites of the polyamine metabolism. Furthermore, UA increased the intracellular accumulation of Dox in MCF-7/ADR cells. Taken together, UA can inhibit against tumor progression during the treatment of breast cancer with Dox, and possibly modulate the Erk-VEGF/MMP-9 signaling pathways and polyamine metabolism by targeting ODC to exert these effects.