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25 January 2012, Volume 28 Issue 1

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Cover and Content of Chemical Research in Chinese Universities Vol.28 No.1(2012)

2012, 28(1):  0-0. 

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Articles

Synthesis and Conductivity of Undecatungstocobaltoruthenic Polyoxometallic Acid

XU Sheng-xian, WU Qing-yin, YAN Wen-fu

2012, 28(1):  1-3. 

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Undecatungstocobaltoruthenic polyoxometallic acid H₇[Ru(H₂O)CoW₁₁O₃₉]·22H₂O was synthesized by the stepwise acidification and the stepwise addition of solutions of the component elements as well as the ion exchanging- cooling method. The optimal proportion of the component compound and the pH of the synthesis reaction were given. The product was characterized by means of inductively coupled plasma(ICP), IR, UV and thermal analysis. The IR and UV results indicate that H₇[Ru(H₂O)CoW₁₁O₃₉]·22H₂O possesses the Keggin structure. The results of AC impedance measurement show that its proton conductivity is 2.30×10^-3 S/cm at room temperature(295 K) and a relative humidity of 75%.



Synthesis, Crystal Structure, Thermal Decomposition and Sensitivity Properties of (AIM)(HTNR) and (AIM)(PA)

TANG Zhan, YANG Li, QIAO Xiao-jing, WU Bi-dong, ZHANG Tong-lai, ZHOU Zun-ning, YU Kai-bei

2012, 28(1):  4-8. 

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Two new energetic compounds (AIM)(HTNR) and (AIM)(PA)(AIM=2-azidoimidazole, TNR=2,4,6-trinitroresorcinol, PA=picric acid) have been prepared by AIM(2-azidoimidazolium) and TNR(2,4,6-trinitroresorcinol) or PA(picric acid) and characterized by elemental analysis and FTIR spectrum. Their crystal structures were determined by X-ray single-crystal diffraction analysis. The obtained results show that (AIM)(HTNR) crystal belongs to monoclinic, P2₁/c space group, a=1.1306(2) nm, b=0.70305(14) nm, c=1.7398(4) nm, β=106.91°, V=1.3231(5) nm³, D_c=1.778 g/cm³, Z=4, R₁=0.0524, wR₂[I>2σ(I)]=0.1067 and S=1.092 and (AIM)(PA) crystal belongs to monoclinic P2₁/c space group, a=0.80303(16) nm, b=0.81395(16) nm, c=2.0471(4) nm, β=93.93(3)°, V=1.3349(5) nm³, D_c=1.683 g/cm³, Z=4, R₁=0.0784, wR₂[I>2σ(I)]=0.1814 and S=1.098. Both the compounds have electrostatic attraction and hydrogen bonds, which contribute to making the constructions more stable. The decomposition of the two compounds was studied via differential scanning calorimetry(DSC) and thermogravimetry-derivative thermogravimetry(TG-DTG) techniques at a heating rate of 10 ℃/min, and the results show that both the compounds underwent one intensive exothermic decomposition stage. Sensitivity tests reveal that the title compounds were insensitive to friction and impact and sensitive to flame and could be applied in potential pyrotechnics.



Effects of MoO₃ Amounts on Sintering and Electrical Properties of Ce_0.8Nd_0.2O_1.9

ZHOU De-feng, ZHAO Gui-chun, YANG Mei, XIA Yan-jie, MENG Jian

2012, 28(1):  9-13. 

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The high purity (Ce_0.8Nd_0.2O_1.9)_1-x(MoO₃)_x(x=0, 0.005, 0.010, 0.020; Ce_0.8Nd_0.2O_1.9=NDC) solid solutions were prepared by modified sol-gel method. The structures and electric conductivities were characterized by X-ray diffraction(XRD), field-emission scanning electron microscopy(FESEM) and electrochemical impedance spectroscopy( EIS). The XRD results show that the materials were pure phase with a cubic fluorite structure. Compared to the undoped-NDC samples, MoO3 doped-NDC showed higher sintered density(over 96%) at reduced sintering temperature. The electric conductivity(σ_t) of (Ce_0.8Nd_0.2O_1.9)_1-x(MoO₃)_x at 400 ℃ was 9.58×10^–4 S/cm when x=0.010, which was higher than that of undoped-NDC samples(σ_t=3.29×10^–4 S/cm). The obtained optimal amount of the MoO₃ was x=0.010 in this system.



Analysis of Peanut Oil Adulterated with Other Edible Oils by Spectrophotometry

SU Rui, WANG Xing-hua, ZHAO Tian-qi, YU Wen-zhi, FENG Xu-dong, ZHANG Han-qi, YU Ai-min

2012, 28(1):  14-18. 

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Since peanut oil(PO) is more expensive than other seed oils, some PO is adulterated with other cheap seed oils, such as soybean oil, palm olein, cottonseed oil, corn oil and rapeseed oil. The conventional method for determining whether PO was adulterated is to detect the freezing point of oils. The proposed method for the determination of adulterants in PO was based on monitoring the change of absorbance when the sample was refrigerated. A special spectrophotometer was developed. A total of 10 kinds of POs from different suppliers were chosen and adulterated with other seed oils at the volume fraction levels ranging from 5% to 30%. A total of 150 samples were analyzed by the proposed method and the results were satisfactory.



Electrochemical Impedance of Ethanol Oxidation in Alkaline Media

DANAEE Iman, JAFARIAN Majid, GOBAL Fereydoon, SHARAFI Mahboobeh, MAHJANI Mohammad-ghasem

2012, 28(1):  19-25. 

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Nickel modified NiOOH electrodes were used for the electrocatalytic oxidation of ethanol in alkaline solutions. The electro-oxidation of ethanol in a 1 mol/L NaOH solution at different concentrations of ethanol was studied by ac impedance spectroscopy. Electrooxidation of ethanol on Ni shows negative resistance on impedance plots. The impedance shows different patterns at different applied anodic potential. The influence of the electrode potential on impedance was studied and a quantitative explanation for the impedance of ethanol oxidation was given by means of a proposed mathematical model. At potentials higher than 0.52 V(vs. Ag/AgCl), a pseudoinductive behavior was observed, but at those higher than 0.57 V, impedance patterns were reversed to the second and third quadrants. The conditions required for the reversing of impedance pattern were delineated with the impedance model.



On-line Preconcentration and Determination of Trace Metals in Water Samples by Flow Injection Combined with Flame Atomic Absorption Spectrometry via Calix[4]arene Carboxylic Acid Packed Micro-column

GUO Da-wang, ZHAO Xiao-wei, JIA Qiong, ZHOU Wei-hong

2012, 28(1):  26-30. 

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An adsorbent calix[4]arene carboxylic acid was employed as the adsorption material for on-line flow injection( FI) micro-column preconcentration coupled with flame atomic absorption spectrometry(FAAS) determination of trace heavy metals(Cu, Pb, Co, Ni and Cd). Parameters such as the pH, loading time and flow rate of sample, and the concentration, volume and flow rate of eluent were optimized. The enrichment factors are 50.0, 56.5, 11.6, 12.1 and 19.1 for Cu, Pb, Co, Ni, and Cd, respectively, and a sample throughput of 20 h^-1 was obtained. The limits of detection for Cu, Pb, Co, Ni, and Cd were in a range of 1.56―3.91 μg/L, and the relative standard deviations(RSDs) were less than 2.76%(n=7). Furthermore, the proposed method was successfully applied to the determination of Cu, Pb, Co, Ni, and Cd in certified reference materials and various water samples.



Analysis of Low-polar Ginsenosides in Steamed Panax Ginseng at High-temperature by HPLC-ESI-MS/MS

ZHANG Yu-chi, PI Zi-feng, LIU Chun-ming, SONG Feng-rui, LIU Zhi-qiang, LIU Shu-ying

2012, 28(1):  31-36. 

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A high performance liquid chromatography coupled with electrospray ionization-tandem mass spectrometry( HPLC-ESI-MS/MS) method was developed for the analysis and identification of ginsenosides in the extracts of raw Panax ginseng(RPG) and steamed Panax ginseng at high temperatures(SPGHT). A total of 25 ginsenosides were extracted include of which 10 low-polar ginsenosides, such as ginsenosides F4, Rk3, Rh4, 20S-Rg3, 20R-Rg3 and so on, were identified according to their HPLC retention time and MS/MS data. The results indicated that the low polar ginsenosides were seldom found in RPG. For the exploration of the transformation pattern of the ginsenosides in steam processing, the standards of ginsenosides Re, Rg1, Rb1, Rc, Rb2, Rb3 and Rd were selected and hydrolyzed at a temperature of 120 ℃. The results show that these polar ginsenosides can be converted to low-polar ginsenosides such as Rg2, Rg6, F4, Rk3 and Rg5 by hydrolyzing the sugar chains.



Real-time Monitoring of Nucleotide Excision of Molecular Beacon Catalyzed by Klenow Fragment

LIU Bin, YANG Xiao-hai, WANG Ke-min, TAN Wei-hong

2012, 28(1):  37-40. 

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Klenow fragment(KF) uses the activity of a separate exonuclease to excise nucleotide, which is a crucial step in DNA replication and repair. Here is a novel sensitive and convenient method introduced for real-time monitoring nucleotide excision by KF with a molecular beacon as a detecting probe in a homogeneous solution. This method, which overcomes the drawbacks of traditional methods such as discontinuity, time consuming and low sensitivity, was used to assay KF activity and the detection limit reached up to 0.4 U/mL. In addition, the method was applied to investigating the effects of metal ions and chemical drugs on the reaction. The results demonstrate that it is a potential high-throughput assay for screening inhibitors and activity analysis of KF in vitro.



Sequential Extraction of Natural Surface Coatings: Comparison with Single Stage Extraction and Its Application in Investigating Adsorption Characteristics of Surface Coating Components for Metals

HUA Xiu-yi, LIU Xiao-xue, DONG De-ming, LI Ming, LI Yao-rui

2012, 28(1):  41-46. 

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Multistage sequential extraction with different sequences was applied to extracting natural surface coatings( NSCs), and the results were compared with those by single stage extraction technique. The optimal sequential extraction scheme with the best performance was selected and incorporated into the method of selective extraction followed by adsorption and statistic analyses to study the adsorption parameters of Fe oxides, Mn oxides and organic matters in NSCs for Pb and Cd, to validate the applicability of the sequential extraction scheme. The Langmuir adsorption parameters of each component of surface coating estimated according to the adsorption data of single stage extraction of NSCs were all similar to those of sequential extraction of NSCs, and the maximum difference between the metal adsorption abilities of the components estimated via the two extraction techniques was only about 20%, indicating that either extraction techniques could be used. The optimal sequential extraction scheme obtained was first extracted with NH₂OH·HCl, then with Na₂S₂O₄, and finally with oxalic acid.



Comparison of Photochemical Reactions of m-Cresol in Aqueous Solution and in Ice

PENG Fei, XUE Hong-hai, TANG Xiao-jian, KANG Chun-li, LI Lin-lin, LI Zhe

2012, 28(1):  47-52. 

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We compared the photochemical reaction of m-cresol containing OH precursors such as H₂O₂, NO₂^- and NO₃^- in aqueous solution with those in ice. The results show that the conversion rate of m-cresol in aqueous solution was higher than that in ice. H₂O₂, NO₂^- and NO₃^- all accelerated the photoconversion of m-cresol in both aqueous solution and ice. The photochemical reactions of m-cresol obeys the first order kinetics equation. According to the photoproducts identified by GC-MS, we proposed that hydroxylation and nitration reactions occurred in both aqueous solution and ice. Coupling reaction was common in ice, however, in aqueous solution it was found only in UV system. Our results suggest that the photochemical reactions of m-cresol were different in aqueous solution and in ice.



Synthesis, Crystal Structure and Biological Activities of Novel Anthranilic(Isophthalic) Acid Esters

YAN Tao, YU Guan-ping, LIU Peng-fei, XIONG Li-xia, YU Shu-jing, LI Zheng-ming

2012, 28(1):  53-56. 

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In search of environmentally benign insecticides with high activity, low toxicity and low resistance, a series of novel anthranilic(isophthalic) acid esters was designed and synthesized based on the structure of ryanodine modulating agent. All the compounds were characterized by ¹H NMR spectra, elemental analysis or high resolution mass spectrometry(HRMS). The preliminary results of biological activity assessment indicate that some of the title compounds exhibit certain but unremarkable insecticidal activity against Mythimna separata Walker at 200 mg/L and fungicidal activities against five funguses at 50 mg/L.



Synthesis of 6-(Bromomethyl)-4-methoxy-5,6,7,8-tetrahydropyrido- [3,2-d]pyrimidin-2-ol from 6-Methylpyrimidine-2,4-diol

LIU Wei-dong, DENG Xi-ling, ZHANG Zhi-li, WANG Xiao-wei, LIU Jun-yi

2012, 28(1):  57-60. 

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6-(Bromomethyl)-4-methoxy-5,6,7,8-tetrahydropyrido[3,2-d]pyrimidin-2-ol(compound 9) was synthesized from 6-methylpyrimidine-2,4-diol(compound 1) through the crucial steps of 6-methyl alkylating and intramolecular cyclization. The assignment of the structure of compound 9 was performed by its spectral data, ¹H NMR, ¹³C NMR, HMBC, and HRMS spectra.



Synthesis and in vitro Antimycobacterial Activity of Moxifloxacin Methylene and Ethylene Isatin Derivatives

FENG Lian-shun, LIU Ming-liang, WANG Shuo, CHAI Yun, LI Su-jie, GUO Hui-yuan

2012, 28(1):  61-66. 

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A series of novel moxifloxacin methylene and ethylene isatin derivatives with remarkable improvement in lipophilicity, compared to the parent moxifloxacin, was designed, synthesized and characterized by 1H NMR, MS and HRMS. These derivatives were initially evaluated for their in vitro antimycobacterial activity against M. smegmatis CMCC 93202. Compounds 3a―3f, 5a, 5f and 5j were chosen for the further evaluation of their in vitro activity against Mycobacterium tuberculosis(MTB) H37Rv ATCC 27294 and MDR-MTB 09710. All the target compounds[ minimum inhibitory concentration(MIC): 0.39―>16 μg/mL] were far more active than rifampin(MIC: 2.0―>256 μg/mL), but less active than moxifloxacin(MIC: 0.1―1.0 μg/mL) against the three tested strains. The most active compounds 3a and 3c were found to be 2―64 fold more potent than isoniazid and rifampin against M. smegmatis CMCC 93202, 2 fold more potent than rifampin against MTB H37Rv ATCC 27294, and 16―>64 fold more potent than ethambutol, isoniazid and rifampin against MDR-MTB 09710.



RuCl₃·3H₂O Mediated Olefin Isomerizations in Ionic Liquids: A Highly Recyclable System for Olefin Isomerizations

SHAO Ming-bo, LIU Gui-yan, ZHAO Jing-jing, WANG Xiao-yu, WANG Jian-hui

2012, 28(1):  67-69. 

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Herein lies a convenient and highly efficient method of olefin isomerization in the presence of RuCl₃·3H₂O in ionic liquid(IL). More importantly, RuCl₃·3H₂O is a robust and recyclable catalyst. Nine cycles of RuCl₃·3H₂O as the catalyst were performed for the isomerization reactions of the selected substrate in IL and MeOH.



Chemoenzymatic Synthesis of Ramosetron Hydrochloride

LIU Qing-wen, XU Hao, TIAN Hua, ZHENG Liang-yu, ZHANG Suo-qin

2012, 28(1):  70-72. 

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A new method for the synthesis of ramosetron hydrochloride, the most wildly used 5-HT₃ receptor antagonist, was reported. The intermediate 8 was obtained in a high e.e. value via lipase catalyzed hydrolytic kinetic resolution. Then enantiomerically pure ramosetron hydrochloride was synthesized in two steps with excellent yield (the total yield is 24.6%). The method provides a new environment friendly and atom economy way to synthesize enantiomerically pure ramosetron.



Synthesis, Crystal Structures and Catalysis of Dinuclear Cd(Ⅱ) Complexes Bridged by Unusual (N,O,O′)-Coordinated α-Amino Acids

DENG Dong-sheng, WANG Li, PEI Ya-mei, FENG Lu, LIU Chang-lin

2012, 28(1):  73-78. 

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Four dinuclear amino acid cadmium(Ⅱ) complexes [Cd₂(tren)₂(dl-alaninato)](ClO₄)₃·H₂O(Ⅰ), [Cd₂(tren)₂·(l-alaninato)](ClO₄)₃·H₂O(Ⅱ), [Cd₂(tren)₂(dl-phenylalaninato)](ClO₄)₃(Ⅲ) and [Cd₂(tren)₂(l-phenylalaninato)]· (ClO₄)₃(Ⅳ), constructed from mixed ligands of tris(2-aminoethyl)amine(tren) and racemic or natural amino acids( amino acids=dl- or l-alanine, and dl- or l-phenylalanine), have been synthesized and characterized by X-ray crystallography. The structural analysis of complexes Ⅰ and Ⅲ reveals that the cadmium centers are coordinated by one tren ligand and one amino acid molecule with the unusual (N,O,O′)-bridged mode, resulting in asymmetric chromophores of CdN₄O and CdN₅O in complex Ⅰ, CdN₄O₂ and CdN₅O in complex Ⅲ, respectively. The utility of the four complexes as efficient water-compatible Lewis acid catalysts for the direct aldol reaction in water was examined. The reaction proceeded smoothly to afford the corresponding β-hydroxy ketones in up to 99% yield. Moreover, the diastereoselectivity of the reaction favors the formation of the syn-isomers.



Impact of Interleukin-28B Polymorphism on Response to Treatment in Chinese Hepatitis C Patients

L� Jian-nan, WANG Song, XU Yan, ZHANG Man-hua, SIQING Tunala, JI Shang-wei, JIAO Jian, WANG Xu, WANG Jiang-bin

2012, 28(1):  79-83. 

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The candidate polymorphism rs12979860 of interleukin 28B(IL28B) gene was genotyped by means of polymerase chain reaction(PCR) amplification and direct PCR sequencing, and then the role of this single nucleotide polymorphism(SNP) in the response to the treatment of 172 Chinese patients with hepatitis C virus(HCV) chronic infection was analyzed. The results show that the frequencies of major homozygotes(CC) and heterozygotes(CT) of rs12979860 were 0.84 and 0.16, respectively, and the minor homozygotes(TT) wasn't found in this cohort. A highly significant association was found between the CC genotype and sustained virological response(SVR) in HCV genotype 1 infected patients(P<0.001) but not in HCV non-genotype 1 infected patients. In addition, a strong association was found between rs12979860 CC genotype and rapid virological response(RVR) in both HCV genotype 1 infected patients(P<0.001) and non-genotype 1 infected patients(P<0.001). Taken together, these results indicate that IL28B polymorphism plays a key role in response to hepatitis C therapy in Chinese patients. Combine assessment of clinical predictors and the IL28B polymorphism may be beneficial to the individualized treatment decision in Asian chronic hepatitis C(CHC) patients.



Taurine Inhibits Myocardial Fibrosis via PKC-ERK1/2 Signaling Pathways

WANG Li-ying, LI Hong, YANG Shi-jie

2012, 28(1):  84-90. 

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Previous studies have demonstrated the important role of taurine in inhibiting proliferation of myofibroblasts( myoFb) and myocardial fibrosis. However, the underlying mechanisms are unclear. The present study was designed to shed light on this issue through exploring the signal pathways via in vitro experiments. Angiotension Ⅱ (AngⅡ) treatment significantly increased myoFb proliferation and the levels of collagens Ⅰ and Ⅲ(P<0.05), whereas taurine, PKCα(PKC: protein kinase C) specific inhibitor L-threo-dihydro-sphingosine(D4681), ERK1/2 inhibitor (PD98095) abrogated myoFb proliferation and collagen levels(P<0.05, P<0.01, respectively), and increased the G₀/G₁ phase rate and decreased S phase rate. Immunocytochemistry, confocal fluorescence staining and image analysis showed that taurine could inhibit the translocation and expression of p-PKCαin membrane, and then inhibit nuclear translocation and expression of p-ERK1/2. These results have statistically significant differences compared with those of AngⅡ group(P<0.01). Western blot results also show that taurine could inhibit the protein expression of p-PKCα and p-ERK1/2. We used p-PKCα specific inhibitor D4681 in order to elucidate the relationship between p-PKCα and p-ERK1/2 in signal transduction pathways. Finally, the results show that the protein expression of p-ERK1/2 and nuclear translocation were suppressed in D4681 group.



Safe and Objective Assay of Enterovirus 71 Neutralizing Antibodies via Pseudovirus

JIN Jun, XU Lin, GUO Shi-jie, SUN Shi-yang, ZHANG Shu, ZHU Chang-lin, KONG Wei, JIANG Chun-lai

2012, 28(1):  91-95. 

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Current serum neutralization assays based on the inhibition of the cytopathic effect(Nt-CPE) need to manipulate live viruses, which are time-consuming, labor-intensive, and have the potential exposure to infectious agents, so a safe and objective assay via pseudovirus for the fast and efficient detection of enterovirus 71(EV71) neutralizing antibodies was developed. First, we generated EV71 pseudovirus containing firefly luciferase gene in place of the capsid gene P1 in EV71 genome. Vero cells infected with 200 CCID₅₀(50% cell culture infective dose) of EV71 pseudovirus for 24 h were found to have the best performance. Seval sera were measured by EV71 pseudoparticle neutralization assay(Nt-PPN) and the conventional serological method Nt-CPE. Neutralizing antibody titers measured by Nt-PPN and those obtained by Nt-CPE demonstrate a high correlation between the two methods. Overall, the PPN assay represents a valid alternative to conventional serological methods for the evaluation of EV71 neutralizing antibodies. This method can be used for detecting neutralizing antibodies of other picornaviruses, such as hepatitis A virus( HAV) and coxsackievirus 16(CVA16), and make it possible to determine whether there is cross-reactivity between EV71 and CVA16.



Molecular Targets of Combined Natural Antioxidants Against Diabetes in Streptozotocin-induced Diabetic Mice

SONG Yang, GAO Zhong-li, DU Zhen-wu, PIAO Song-lan, WANG Ling-ling, WANG Qing, ZHANG Gui-zhen

2012, 28(1):  96-102. 

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Natural antioxidants, due to the different chemical structures and their unique biological protection effects on islet cell, have been received much attention in applied chemistry field for developing a new diabetic drug. However, the molecular targets of the islet cell protection have been remained obscure. For investigating molecular targets of combined natural antioxidant's(CNA) roles in against diabetes, type 1 diabetic mouse model was made by multiple injection of low doses of streptozotocin into C57BL mice. Two combinations of natural antioxidants were orally supplemented to the mice. Blood glucose level, glutathione peroxidase(GSH-Px) and superoxide dismutase (SOD) activities, and malondialdehyde(MDA) contents were measured via biochemical assays. Tumor necrosis factor α(TNF-α), interferon γ(IFN-γ) and Interleukin-12(IL-12) in CD4⁺ Peripheral blood mononuclear cells(PBMC) were evaluated with flow cytometry(FCM). In situ hybridization(ISH) and immunohistochemistry(IHC) were used to detect insulin gene expression. The results demonstrate both the combinations significantly: increased GSH-px and SOD, but decreased MDA levels in pancreas(p<0.05―0.01); up-regulated insulin expression at both mRNA and protein levels in islet cells(p<0.05―0.01); down-regulated TNF-α and IL-12 expression in PBMC(p<0.05―0.01). Our data suggest that the CAN may regulate multiple key molecular targets related to β cell function, including reduction of oxidative stress and pre-inflammatory cytokines, and upregulate insulin gene expression to reduce the development of diabetes.



Screening of Proteins Interacting with Nonstructural 1 Protein of H5N1 Avian Influenza Virus from T7-phage Display Library

ZHU Chun-yu, SUN Ting-ting, ZHAO Jian, WANG Ning, ZHENG Fang-liang, AI Hai-xin, ZHU Jun-feng, WANG Xiao-ying, ZHU Ying, WU Jian-guo, LIU Hong-sheng

2012, 28(1):  103-107. 

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Avian influenza virus(AIV) nonstructural 1(NS1) gene was amplified by real-time polymerse chain reaction( RT-PCR) and inserted into pET28a, then transformed into E. coli BL21(DE3) competent cell. With the induction of isopropyl-β-D-thiogalactoside(IPTG) and the purification of Ni-NTA column, we finally obtained purified NS1 protein. T7-phage display system was used to screen the proteins that interacted with NS1 from lung cell cDNA library. The selected positive clones were identified by DNA sequencing and analyzed by BLAST program in Gene- Bank. Two proteins were obtained as NS1 binding proteins, Homo sapiens nucleolar and coiled-body phosphoprotein 1(NOLC1) and Homo sapiens similar to colon cancer-associated antigen. By co-immunoprecipitation and other methods, Homo sapiens NOLC1 was found to interact with the NS1 protein, the results would provide the basis for further studying biological function of NS1 protein.



Microwave-assisted Solid-phase Synthesis, Biological Evaluation and Molecular Docking of Angiotensin I-converting Enzyme Inhibitors

SUN Yang, HUANG Da-wei, LI Xiao-hui, HU Jian-en, XIU Zhi-long

2012, 28(1):  108-113. 

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Short peptides based on the tripeptides, Leu-Arg-Pro and Leu-Lys-Pro, were synthesized by microwaveassisted solid-phase synthesis method, in order to make a search for potential inhibitors for angiotensin I-converting enzyme(ACE) with minimum side effects in the treatment of hypertension. One peptide with the sequence Leu-Arg-Pro-Phe-Phe shows the strongest inhibition towards ACE with an IC50 value of 0.26 μmol/L in vitro. The study of structure-activity relationship shows that the introduction of a bulky group into the N-terminal of this series of inhibitors may enlarge steric hindrance, resulting in the poor inhibitory activity towards ACE. The inhibitory activity decreased in turn when L-Pro, D-Pro or Ac6c was at the C-terminal respectively. The binding interaction between each of these inhibitors and testicular ACE(tACE) was performed by molecular docking. The results suggest that Leu-Arg-Pro-Phe-Phe mainly occupied the S1 subsite of tACE, and made contact with tACE via seven H-bonds. It appeared that the site on the peptide that bound with tACE was influenced by the configuration of the amino acid, L- or D-form, at the C-terminal of the peptide.



Dose-dependent Cytotoxicity and Oxidative Stress Induced by “Naked” Fe₃O₄ Nanoparticles in Human Hepatocyte

LIN Xin-li, ZHAO Shu-hua, ZHANG Long, HU Gui-qin, SUN Zhi-wei, YANG Wen-sheng

2012, 28(1):  114-118. 

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The dose-dependent cytotoxicity effect on human hepatocyte(HL-7702 cells) induced by “naked” Fe3O4 nanoparticles was assessed through cell viabilities and lactate dehydrogenase(LDH) activities. Three important oxidative indexes of the cells by glutathione peroxidase(GSH-Px), superoxide dismutase(SOD) and malondialdehyde( MDA) were determined. The good correlation of the cell viabilities with their GSH-Px, SOD and MDA levels indicated that the cytotoxicity is related to activation of oxidative stress induced by Fe₃O₄ nanoparticles. The oxidative stress also leads to corresponding DNA damage in a similar dose-dependent manner, followed by the changes of cell cycle and cell apoptosis. Such work provides important experimental data for the safety evaluation of superparamagnetic Fe₃O₄ nanoparticles.



Catalytic Performance and Texture of TEOS Based Cu/SiO₂ Catalysts for Hydrogenation of Dimethyl Oxalate to Ethylene Glycol

WANG Shu-rong, YIN Qian-qian, LI Xin-bao

2012, 28(1):  119-123. 

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Highly active and selective Cu/SiO₂ catalysts for hydrogenation of dimethyl oxalate(DMO) to ethylene glycol(EG) were successfully prepared by means of a convenient one-pot synthetic method with tetraethoxysilane( TEOS) as the source of silica. XRD, H₂-TPR, SEM, TEM, XRF and N₂ physisorption measurements were performed to characterize the texture and structure of Cu/SiO2 catalysts with different copper loadings. The active components were highly dispersed on SiO₂ supports. Furthermore, the coexistence of Cu⁰ and Cu⁺ contributed a lot to the excellent performance of Cu-TEOS catalysts. The DMO conversion reached 100% and the EG selectivity reached 95% at 498 K and 2 MPa with a high liquid hourly space velocity over the 27-Cu-TEOS catalyst with an actual copper loading of 19.0%(mass fraction).



Rapid Fabrication of CdS Nanocrystals with Well Mesoporous Structure Under Ultrasound Irradiation at Room Temperature

YU Chang-lin, ZHOU Wan-qin, YU Jim-my, YANG Jian-gao, FAN Qi-zhe

2012, 28(1):  124-128. 

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Sphere-like mesoporous CdS nanocrystals with high crystallinity and big surface area were successfully fabricated by ultrasound irradiation at room temperature. The as-synthesized CdS with and without ultrasound irradiation was investigated by the characterizations of X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), and Brunauer-Emmett-Teller(BET) surface areas. The photocatalytic activity of the CdS was evaluated by photocatalytic degradation of methyl orange under visible light(λ>420 nm) irradiation. A possible mechanism for the formation of the CdS nanocrystals with mesoporous structure under ultrasound irradiation was proposed. The results show that both the template role of the triblock copolymer of P123 and the effect of ultrasound-induced aggregation are mainly responsible for the formation of mesoporous structure. On the other hand, the energy generated from acoustic cavitation can effectively accelerate the crystallization process of the amorphous CdS.



Separation of H₂O/CO₂ Mixtures with Layered Adsorption Method for Greenhouse Gas Control

XU Dong, ZHANG Jun, LI Gang, XIAO Penny, ZHAI Yu-chun

2012, 28(1):  129-132. 

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Multiple-layered vacuum swing adsorption technique was used and investigated in order to effectively keep the feed gas that flows into zeolite 13X zone being dry and keep the CAPEX down(not adding pre-treatment equipment). Activated carbon fiber(ACF) and alumina CDX were laid at the lower parts of the column as pre-layers to selectively adsorb moisture. Zeolite 13X was laid on the top of those two adsorbents as the main layer to capture CO₂. Systematic cyclic experiments show that water vapor was successfully contained within the ACF and CDX layers at cyclic steady states. It was also found that ultimate vacuum pressure played a decisive factor for stabilizing the water front, and achieving good CO₂ purity and recovery. The findings also reveal the pathway for large-scale CO₂ capture process.



Electrodeposition and Characterization of Polyaniline Film

WANG Hong-zhi, ZHANG Peng, ZHANG Wei-guo, YAO Su-wei

2012, 28(1):  133-136. 

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Polyaniline film was prepared by electrochemical method in an acidic solution of aniline. The micromorphology of the polyaniline film was transformed to three-dimensional network structure instead of little particles while the deposition time was extended. The peak wavelength of the photoluminescence spectrum was 491 nm. The luminous intensity increased with the extension of deposition time, and so did the electrochemical activity.



Molecular Docking of 3-Methylindole-containing Drugs Binding into CYP3A4

MENG Xuan-yu, LI Zhuo, NIU Rui-juan, ZHANG Hong-xing, ZHENG Qing-chuan

2012, 28(1):  137-141. 

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Drugs SPD-304(6,7-dimethyl-3-{[methyl-(2-{methyl-[1-(3-trifluoromethyl-phenyl)-1H-indol-3-ylmethyl]- amino}-ethyl)-amino]-methyl}-chromen-4-one) and zafirlukast contain a common structural element of 3-substituted indole moiety which closely relates to a dehydrogenated reaction catalyzed by cytochrome P450s(CYPs). It was reported that the dehydrogenation can produce a reactive electrophilic intermediate which cause toxicities and inactivate CYPs. Drug L-745,870(3-{[4-(4-chlorophenyl)piperazin-1-yl]-methyl}-1H-pyrrolo- 2,3-β-pyridine) might have similar effect since it contains the same structural element. We used molecular docking approach combined with molecular dynamics(MD) simulation to model three-dimensional(3D) complex structures of SPD-304, zafirlukast and L-745,870 into CYP3A4, respectively. The results show that these three drugs can stably bind into the active site and the 3-methylene carbons of the drugs keep a reasonable reactive distance from the heme iron. The complex structure of SPD-304-CYP3A4 is in agreement with experimental data. For zafirlukast, the calculation results indicate that 3-methylene carbon might be the dehydrogenation reaction site. Docking model of L-745,870-CYP3A4 shows a potential possibility of L-745,870 dehydrogenated by CYP3A4 at 3-methylene carbon which is in agreement with experiment in vivo. In addition, residues in the phenylalanine cluster as well as S119 and R212 play a critical role in the ligands binding based on our calculations. The docking models could provide some clues to understand the metabolic mechanism of the drugs by CYP3A4.



Alumina Solubility in Na₃AlF₆-K₃AlF₆-AlF₃ Molten Salt System Prospective for Aluminum Electrolysis at Lower Temperature

LI Jie, YUAN Chang-fu, TIAN Zhong-liang, WANG Jia-wei, LAI Yan-qing, LIU Ye-xiang

2012, 28(1):  142-146. 

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The alumina solubility in the title system within the composition range of KR{m(K₃AlF₆)/[m(K₃AlF₆)+ m(Na₃AlF₆)]} 10%―50%, a ternary Na₃AlF₆-K₃AlF₆-AlF₃ molten system with 23%―29%(mass fraction) AlF₃ was investigated by measuring the mass loss of a rotating sintered corundum disc. And the following empirical equation was derived when superheat degree was no more than 60 ℃: w(Al₂O₃)_sat=A×(T/1000)^B, where A= –1.85774+ 26.754234w(AlF₃)^–0.3683–0.00783KR^2.363+0.010266KR^2.3048+0.7902w(AlF₃)^0.00652, B=112.4625–53.2567w(AlF₃)^0.4236+ 5.1079w(AlF₃)^0.9241+0.01542w(AlF₃)^1.3540. Considering both higher alumina solubility and not too high superheat degree are required, alumina solubility of different compositions at not the same temperature but the same superheat degree was studied, which will be more industrial helpful for selecting prospective compositions. The results show that the composition deserved to be further tested in lower temperature cells is 10%―30% KR and 23%―26%(mass fraction) AlF₃.



Theoretical Study of CH₃CH=CH₂+O(¹D) Reaction: Mechanism and Kinetics

WU Nan-nan, LIU Hong-xia, DUAN Xue-mei, LIU Jing-yao

2012, 28(1):  147-152. 

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The mechanism and kinetics for the reaction of propene(CH₃CH=CH₂) molecule with O(¹D) atom were investigated theoretically. The electronic structure information of the potential energy surface(PES) was obtained at the B3LYP/6-311+G(d,p) level, and the single-point energies were refined by the multi-level MCG3-MPWB method. The calculated results show that O(¹D) atom can attack CH₃CH=CH₂ via the barrierless insertion mechanism to form four energy-riched intermediates CH₃C(OH)CH₂(IM1), CH₃CHCHOH(IM2), CH₂OHCHCH₂(IM3) and cyclo- CH₂OCHCH₃(IM4), respectively, on the singlet PES. The branching ratios as well as the pressure- and temperaturedependence of various product channels for this multi-well reaction were predicted by variational transition-state and Rice-Ramsperger-Kassel-Marcus(RRKM) theories. The present results will be useful to gain a deep insight into the reaction mechanism and kinetics of CH₃CH=CH₂+O(¹D) reaction.



FTIR Spectroscopic Study of Crystallization of Uniaxial Drawn Syndiotactic Polystyrene/Carbon Nanotube Nanocomposite Films

ZHANG Jin-hao, YANG Ji-ping, YUAN Cui-ping, CHEN Guang-ming

2012, 28(1):  153-155. 

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The crystallization of uniaxial hot drawn syndiotactic polystyrene/multi-walled carbon nanotube (sPS/MWCNT) nanocomposite films was studied by FTIR spectroscopy. The effects of MWCNT content, draw ratio and drawing temperature on the sPS crystallinity were investigated. The sPS/MWCMT nanocomposite films show reduced crystallinities with the increase of MWCNT content. In addition, with the increase of draw ratio, both the pure sPS and the sPS/MWCNT nanocomposite drawn films exhibit increased crystallinity. The effect of drawing temperature on the sPS crystallization is complex. In a temperature range of 100―135 ℃, the crystallinity decreases with drawing temperature, whereas it increases at 140 ℃ for both pure sPS and its nanocomposite films.



Preparation and Electrochemical Behaviors of AA-PEGMA Copolymer Film Electrode

L� Xue, LIU Feng-qi

2012, 28(1):  156-161. 

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A new kind of comblike copolymer film composed of acrylic acid-polyethylene glycol monomethyl ether acrylate copolymer(AA-PEGMA copolymer) was successfully synthesized to immobilize hemoglobin(Hb). FTIR, UV-Vis and CD spectra suggest that Hb kept its original structure in the AA-PEGMA copolymer film without denaturation. A pair of well-defined, quasi-reversible cyclic voltammetric peaks at around –270 mV vs. saturated calomel electrode(SCE) for the Hb Fe(Ⅲ)/Fe(Ⅱ) redox couple was observed on the film-modified electrode in phosphate buffer solution(PBS, pH=7.0). The formal potential of Hb/AA-PEGMA copolymer film-modified electrode is linearly dependent on solution pH with a slope of –46.3 mV/pH, illustrating that one-proton transfer was accompanied with each electron transfer. Furthermore, the modified electrode displayed electrocatalytic response to the reduction of H₂O₂ with a linear range of 3.5―126 μmol/L and a detection limit of 1.17 μmol/L. In conclusion, the AA-PEGMA copolymer film was proved to be an excellent matrix for the immobilization and electrochemistry of proteins.



UV-induced Self-initiated Graft Polymerization of Acrylamide onto Poly(ether ether ketone)

CHEN Rui-chao, SUN Hui, LI Ang, XU Guo-zhi

2012, 28(1):  162-165. 

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Photo-grafting of hydrophilic monomer was used to enhance the hydrophilicity of poly(ether ether ketone) (PEEK) with the aim of extending its applications to biological fields. PEEK sheets were surface modified by grafting of acrylamide(AAm) with ultraviolet(UV) irradiation in the presence or absence of benzophenone(BP). The effects of BP, irradiation time and monomer concentration on the surface wettability of PEEK were investigated. Characterization of modified PEEK using scanning electron microscopy(SEM), energy-disperse spectrometer(EDS) and water contact angle measurements shows that AAm was successfully grafted on PEEK surface both in presence and absence of BP. With the increase in irradiation time and monomer concentration, contact angles decrease to as low as 30°, demonstrating a significant improvement of surface hydrophilicity. In agreement with the decrease in contact angle, under identical conditions, the nitrogen concentration increases, suggesting the increase in grafting degree of the grafting polymerization. This investigation demonstrates a self-initiation of PEEK due to its BP-like structure in the backbone of the polymer. Though the graft polymerization proceeds more readily in the presence of BP, the self-initiated graft polymerization is clearly observed.



Preparation, Characterization of Hydrophobic Drug in Combine Loaded Chitosan/Cyclodextrin/Trisodium Citrate Nanoparticles and in vitro Release Study

JI Jin-gou, ZHANG Jing-fen, HAO Shi-lei, WU Dan-jun, LIU Li, XU Yi

2012, 28(1):  166-170. 

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Chitosan/cyclodextrin/trisodium citrate(CS/CD/TSC) nanoparticles with ibuprofen(IBU) loaded were prepared via the ionic cross-linking method, with trisodium citrate selected as the cross-linking agent. The drug-loading capacity, particle size, zeta potential and surface morphology of the obtained nanoparticles were investigated. The results show a good drug-loading capacity. The prepared nanoparticles were spherical in shape with an average size of 293.7 nm and a zeta potential of +30.72 mV. The in vitro release studies show that the controlled release of IBU from the nanoparticles was followed. The drug release from CS/β-CD/TSC nanoparticles followed non-Fickian or anomalous diffusion.