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Sample records for bibenzyl

  1. A new bibenzyl derivative from Pleione bulbocodioides

    Institute of Scientific and Technical Information of China (English)

    Xin Qiao Liu; Qiao Yu Yuan; Yuan Qiang Guo

    2008-01-01

    A new bibenzyl derivative 1, named 2-(4"-hydrixybenzyl)-3-(3'-hydroxyphenethyl)-5-methoxy-cyclohexa-2,5-diene-1,4-dione, and two known stilbenoids (2, 3) were isolated from the tubers of Pleione bulbocodioides (Franch.) Rolfe. Their structureswere elucidated by spectroscopic methods.2008 Xin Qiao Liu. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

  2. Testing a new NIF neutron time-of-flight detector with a bibenzyl scintillator on OMEGA.

    Science.gov (United States)

    Glebov, V Yu; Forrest, C; Knauer, J P; Pruyne, A; Romanofsky, M; Sangster, T C; Shoup, M J; Stoeckl, C; Caggiano, J A; Carman, M L; Clancy, T J; Hatarik, R; McNaney, J; Zaitseva, N P

    2012-10-01

    A new neutron time-of-flight (nTOF) detector with a bibenzyl crystal as a scintillator has been designed and manufactured for the National Ignition Facility (NIF). This detector will replace a nTOF20-Spec detector with an oxygenated xylene scintillator currently operational on the NIF to improve the areal-density measurements. In addition to areal density, the bibenzyl detector will measure the D-D and D-T neutron yield and the ion temperature of indirect- and direct-drive-implosion experiments. The design of the bibenzyl detector and results of tests on the OMEGA Laser System are presented.

  3. Ramberg-B(a)cklund Rearrangement Approaches to the Synthesis of Natural Bibenzyls

    Institute of Scientific and Technical Information of China (English)

    WANG,Xiao-Long(王小龙); LIU,Dong(刘冬); XIA,Ya-Mu(夏亚穆); CAO,Xiao-Ping(曹小平); PAN,Xin-Fu(潘鑫复)

    2004-01-01

    The Ramberg-Backlund rearrangement has been successfully utilized to convert readily available α-and α'-hydrogen bearing substituted dibenzyl sulfones into corresponding stilbene derivatives,which is conveniently followed by hydrogenation in the presence of 10% Pd/C to afford the natural bibenzyls.

  4. Rapid Identification of Bibenzyls of Stemona sessilifolia using Hyphenated LC-UV-NMR and LC-MS Methods

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    As a part of the ongoing search for new constituents of Stemona species in China, chemical investigation of Stemona sessilifolia, a plant used in the traditional Chinese medicine to treat respiratory disorders, was carried out. To identify the chemical components rapidly, a selected sample of S. sessilifolia containing bibenzyls was tested using LC-ESIMS and analyzed further using stop-flow LC-UV-NMR, which was sensitive for the detection of the main constituents. LC microfractions were collected using the LC-UV-NMR technique and HR-EIMS off-line analysis was carried out on the collected fractions. This chemical screening strategy allowed for the on-line identification of the main constituents of S. sessilifolia and provided information that was useful for a further peak-guided isolation procedure.Using these methods, four bibenzyls were isolated: two known compounds, 3,5-dihydroxy-4-methyl bibenzyl(1) and 3,5-dihydroxy-2'-methoxy-4-methyl bibenzyl ( 2 ), and two novel compounds, 3, 3'-dihydroxy-5, 6'-dimethoxy bibenzyl (3) and 3,5-dihydroxy-2' ,5'-dimethoxy bibenzyl (4).

  5. Antifungal bis[bibenzyls] from the Chinese liverwort Marchantia polymorpha L.

    Science.gov (United States)

    Niu, Chong; Qu, Jian-Bo; Lou, Hong-Xiang

    2006-01-01

    Bioassay-guided separation of the antifungal constituents of the Chinese liverwort Marchantia polymorpha L. (Marchantiaceae) led to the isolation of seven bis[bibenzyl]-type macrocycles. On the basis of NMR and MS analyses, the three new compounds plagiochin E (1), 13,13'-O-isoproylidenericcardin D (4), and riccardin H (7) were identified, together with four known compounds: marchantin E (2), neomarchantin A (3), marchantin A (5), and marchantin B (6). Their antifungal activities against Candida albicans were determined by TLC bioautography.

  6. Study of bis(bibenzyls) in bryophytes using electron ionization time-of-flight and electrospray ionization triple-quadrupole mass spectrometry.

    Science.gov (United States)

    Guo, Huaifang; Xing, Jie; Xie, Chunfeng; Qu, Jianbo; Gao, Yanhui; Lou, Hongxiang

    2007-01-01

    A detailed analysis of mass spectra generated from bis(bibenzyl) compounds in bryophytes under electron ionization time-of-flight (EI-TOF) and electrospray ionization triple-quadrupole (ESI-TQ) mass spectrometry conditions is reported. Proposed structures of the fragment ions were obtained by tracking the functional groups of 15 bis(bibenzyls), the structures of which are similar except for some alkoxyl substituents and linkage sites of biphenyl ether bonds. The elucidation was aided by the use of accurate mass measurements. Attempts have been made to provide rational pathways for the formation of these fragment ions, and a generalized fragmentation mechanism is proposed. The bis(bibenzyls) mentioned in this study include three types according to their structure characteristics, i.e. one biphenyl ether bond (A-type), two biphenyl ether bonds (B-type), one biphenyl ether and one biphenyl bond (C-type). The three types display different EI-MS and ESI-MS/MS product profiles, by which the bis(bibenzyl) type and the number of alkoxyl substituents can be identified. Isomers of bis(bibenzyls) can be differentiated to some extent, while the linkage sites of biphenyl ether bonds are difficult to identify. The structure-fragmentation relationships will facilitate the characterization of other bis(bibenzyls) and this will be of value for the high-throughput screening of novel bis(bibenzyls) in bryophytes.

  7. Laser-induced dry-fabrication of bibenzyl molecular layers on the silicon surface

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yong Ping, E-mail: zhangyyping@yahoo.com [Faculty of Materials and Energy, Southwest University, Chongqing 400715 (China); Chen, Zhi Qian [Faculty of Materials and Energy, Southwest University, Chongqing 400715 (China); Dong, Dong [School of Materials Science and Engineering, Northwest Polytechnical University, Xi’an 710072 (China); Xu, Guo Qin, E-mail: chmxugq@nus.edu.sg [Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543 (Singapore)

    2014-08-30

    Graphical abstract: Schematic illustration of photoinduced polymerization of 4-bromostyrene molecules on the Si(1 1 1)-(7 × 7) surface. - Highlights: • Laser-induced fabrication of molecular layer. • XPS and HREELS experimental evidence for the reaction. • DFT explanation of photochemical reaction. - Abstract: The covalently attached organic monolayer has great effects on the structures of the organic semiconductor thin films and their electronic transport properties in the fabrication of molecular electronic devices. A laser-induced dry-fabrication method has been developed to form bibenzyl-like molecular layers by photoinduced reaction of 4-bromostyrene molecules on silicon surface in the vacuum environment. The radical site produced via the C–Br bond cleavage concurrently reacts with the C=C vinyl group of the physisorbed 4-bromostyrene molecule above to form the –CH{sub 2}–CHBr– covalent linkage. X-ray photoelectron spectroscopy (XPS) and high-resolution electron energy loss spectroscopy (HREELS) experimental results and density functional theory (DFT) calculations confirm the formation of covalently bonded bibenzyl-like (Phi–CH{sub 2}–CHBr–Phi) molecular layers on the silicon surface.

  8. Computational Chemistry Meets Experiments for Explaining the Behavior of Bibenzyl: A Thermochemical and Spectroscopic (Infrared, Raman, and NMR) Investigation.

    Science.gov (United States)

    Latouche, Camille; Barone, Vincenzo

    2014-12-09

    The structure, conformational behavior, and spectroscopic parameters of bibenzyl have been investigated by a computational protocol including proper treatment of anharmonic and hindered rotor contributions. Conventional hybrid functionals overstabilize the anti conformer while low-order post-Hartree-Fock (MP2) approaches strongly favor the gauche conformer. However, inclusion of semiempirical dispersion effects in density functionals or coupled cluster post-Hartree-Fock models agree in forecasting the simultaneous presence of both conformers in the gas phase with a slightly larger stability (0.7 kcal·mol(-1)) of the gauche conformer. Addition of thermal and entropic effects finally leads to very close Gibbs free energies for both conformers and, thus, to a slight preference for the gauche form due to statistical factors (2 vs 1). The situation remains essentially the same in solution. On these grounds, perturbative vibrational computations including both electrical and mechanical anharmonicities lead to IR and Raman spectra in remarkable agreement with experiment. Full assignment of the IR spectra explains the presence of peaks from gauche or anti conformers. Comparison between computed and experimental Raman spectra confirms that both conformers are present in liquid phase, whereas the anti conformer seems to be preponderant in the solid state. Also computed NMR parameters are in good agreement with experiment.

  9. Effect of plagiochin E, an antifungal macrocyclic bis(bibenzyl), on cell wall chitin synthesis in Candida albicans

    Institute of Scientific and Technical Information of China (English)

    Xiu-zhen WU; Ai-xia CHENG; Ling-mei SUN; Hong-xiang LOU

    2008-01-01

    Aim: To investigate the effect of plagiochin E (PLE), an antifungal macrocyclic bis(bibenzyl) isolated from liverwort Marchantia polymorpha L, on cell wall chitin synthesis in Candida albicans. Methods: The effect of PLE on chitin synthesis in Candida albicans was investigated at the cellular and molecular lev-els. First, the ultrastructural changes were observed under transmission electron microscopy (TEM). Second, the effects of PLE on chitin synthetase (Chs) activi-ties in vitro were assayed using 6-O-dansyl-N-acetylglucosamine as a fluorescent substrate, and its effect on chitin synthesis in situ was assayed by spheroplast regeneration. Finally, real-time RT-PCR was performed to assay its effect on the expression of Chs genes (CHS). Results: Observation under TEM showed that the structure of the cell wall in Candida albicans was seriously damaged, which suggested that the antifungal activity of PLE was associated with its effect on the cell wail. Enzymatic assays and spheroplast regeneration showed that PLE inhibited chitin synthesis in vitro and in situ. The results of the PCR showed that PLE significantly downregulated the expression of CHS1, and upregulated the expression of CHS2 and CHS3. Because different Chs is regulated at different stages of transcription and post-translation, the downregulation of CHS1 would decrease the level of Chs 1 and inhibit its activity, and the inhibitory effects of PLE on Chs2 and Chs3 would be at the post-translational level or by the inhibi-tion on the enzyme-active center. Conclusion: These results indicate that the antifungal activity of PLE would be attributed to its inhibitory effect on cell wall chitin synthesis in Candida albicans.

  10. 20C, a bibenzyl compound isolated from Gastrodia elata, protects PC12 cells against rotenone-induced apoptosis via activation of the Nrf2/ARE/HO-1 signaling pathway

    Science.gov (United States)

    Huang, Ju-yang; Yuan, Yu-he; Yan, Jia-qing; Wang, Ya-nan; Chu, Shi-feng; Zhu, Cheng-gen; Guo, Qing-lan; Shi, Jian-gong; Chen, Nai-hong

    2016-01-01

    Aim: Our preliminary study shows that a bibenzyl compound isolated from Gastrodia elata, 2-[4-hydroxy-3-(4-hydroxybenzyl)benzyl]-4-(4-hydroxybenzyl)phenol (designated 20C), protects PC12 cells against H2O2-induced injury. In this study we investigated whether 20C exerted neuroprotective action in a cell model of Parkinson's disease. Methods: A cell model of Parkinson's disease was established in PC12 cells by exposure to rotenone (4 μmol/L) for 48 h. Cell viability and apoptosis were assessed, and intracellular ROS level and the mitochondrial membrane potential (MMP) were detected. The expression of apoptosis-related proteins Bax, Bcl-2, cytochrome c, cleaved caspase-3, and oxidative stress-related proteins Nrf2, HO-1 and NQO1 were examined using Western blotting. The mRNA levels of HO-1 and NQO1 were determined with RT-PCR. The nuclear translocation of Nrf2 was observed with immunofluorescence staining. Results: Treatment with rotenone significantly increased the number of apoptotic cells, accompanied by marked increases in the Bax/Bcl-2 ratio, cytochrome c release and caspase-3 activation. Rotenone also increased ROS accumulation, reduced MMP, and increased the nuclear translocation of Nrf2 as well as the mRNA and protein levels of the Nrf2 downstream target genes HO-1 and NQO1 in PC12 cells. Co-treatment with 20C (0.01–1 μmol/L) dose-dependently attenuated rotenone-induced apoptosis and oxidative stress in PC12 cells. Nrf2 knockdown by siRNA partially reversed the protective effects of 20C in rotenone-treated PC12 cells. Conclusion: The bibenzyl compound 20C protects PC12 cells from rotenone-induced apoptosis, at least in part, via activation of the Nrf2/ARE/HO-1 signaling pathway. PMID:27180985

  11. Phytochemical and biological studies of bryophytes.

    Science.gov (United States)

    Asakawa, Yoshinori; Ludwiczuk, Agnieszka; Nagashima, Fumihiro

    2013-07-01

    The bryophytes contain the Marchantiophyta (liverworts), Bryophyta (mosses) and Anthocerotophyta (hornworts). Of these, the Marchantiophyta have a cellular oil body which produce a number of mono-, sesqui- and di-terpenoids, aromatic compounds like bibenzyl, bis-bibenzyls and acetogenins. Most sesqui- and di-terpenoids obtained from liverworts are enantiomers of those found in higher plants. Many of these compounds display a characteristic odor, and can have interesting biological activities. These include: allergenic contact dermatitis, antimicrobial, antifungal and antiviral, cytotoxic, insecticidal, insect antifeedant, superoxide anion radical release, 5-lipoxygenase, calmodulin, hyaluronidase, cyclooxygenase, DNA polymerase β, and α-glucosidase and NO production inhibitory, antioxidant, piscicidal, neurotrophic and muscle relaxing activities among others. Each liverwort biosynthesizes unique components, which are valuable for their chemotaxonomic classification. Typical chemical structures and biological activity of the selected liverwort constituents as well as the hemi- and total synthesis of some biologically active compounds are summarized.

  12. Catalyst system and process for benzyl ether fragmentation and coal liquefaction

    Science.gov (United States)

    Zoeller, Joseph Robert

    1998-04-28

    Dibenzyl ether can be readily cleaved to form primarily benzaldehyde and toluene as products, along with minor amounts of bibenzyl and benzyl benzoate, in the presence of a catalyst system comprising a Group 6 metal, preferably molybdenum, a salt, and an organic halide. Although useful synthetically for the cleavage of benzyl ethers, this cleavage also represents a key model reaction for the liquefaction of coal; thus this catalyst system and process should be useful in coal liquefaction with the advantage of operating at significantly lower temperatures and pressures.

  13. Neutron detection with single crystal organic scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Zaitseva, N; Newby, J; Hamel, S; Carman, L; Faust, M; Lordi, V; Cherepy, N; Stoeffl, W; Payne, S

    2009-07-15

    Detection of high-energy neutrons in the presence of gamma radiation background utilizes pulse-shape discrimination (PSD) phenomena in organics studied previously only with limited number of materials, mostly liquid scintillators and single crystal stilbene. The current paper presents the results obtained with broader varieties of luminescent organic single crystals. The studies involve experimental tools of crystal growth and material characterization in combination with the advanced computer modeling, with the final goal of better understanding the relevance between the nature of the organic materials and their PSD properties. Special consideration is given to the factors that may diminish or even completely obscure the PSD properties in scintillating crystals. Among such factors are molecular and crystallographic structures that determine exchange coupling and exciton mobility in organic materials and the impurity effect discussed on the examples of trans-stilbene, bibenzyl, 9,10-diphenylanthracene and diphenylacetylene.

  14. Toward Direct Reaction-in-Flight Measurements

    Science.gov (United States)

    Wilhelmy, Jerry; Bredeweg, Todd; Fowler, Malcolm; Gooden, Matthew; Hayes, Anna; Rusev, Gencho; Caggiano, Joseph; Hatarik, Robert; Henry, Eugene; Tonchev, Anton; Yeaman, Charles; Bhike, Megha; Krishichayan, Krishi; Tornow, Werner

    2016-03-01

    At the National Ignition Facility (NIF) neutrons having energies greater than the equilibrium 14.1 MeV value can be produced via Reaction-in-Flight (RIF) interactions between plasma atoms and upscattered D or T ions. The yield and spectrum of these RIF produced neutrons carry information on the plasma properties as well as information on the stopping power of ions under plasma conditions. At NIF the yield of these RIF neutrons is predicted to be 4-7 orders of magnitude below the peak 14 MeV neutron yield. The current generation of neutron time of flight (nTOF) instrumentation has so far been incapable of detecting these low-yield neutrons primarily due to high photon backgrounds. To date, information on RIF neutrons has been obtained in integral activation experiments using reactions with high energy thresholds such as 169Tm(n,3n)167Tm and 209Bi(n,4n) 206Bi. Initial experiments to selectively suppress photon backgrounds have been performed at TUNL using pulsed monoenergetic neutron beams of 14.9, 18.5, 24.2, and 28.5 MeV impinging on a Bibenzyl scintillator. By placing 5 cm of Pb before the scintillator we were able to selectively suppress the photons from the flash occurring at the production target and enhance the n/_signal by ~6 times.

  15. Molecular evolution and sequence divergence of plant chalcone synthase and chalcone synthase-Like genes.

    Science.gov (United States)

    Han, Yingying; Zhao, Wenwen; Wang, Zhicui; Zhu, Jingying; Liu, Qisong

    2014-06-01

    Plant chalcone synthase (CHS) and CHS-Like (CHSL) proteins are polyketide synthases. In this study, we evaluated the molecular evolution of this gene family using representative types of CHSL genes, including stilbene synthase (STS), 2-pyrone synthase (2-PS), bibenzyl synthase (BBS), acridone synthase (ACS), biphenyl synthase (BIS), benzalacetone synthase, coumaroyl triacetic acid synthase (CTAS), and benzophenone synthase (BPS), along with their CHS homologs from the same species of both angiosperms and gymnosperms. A cDNA-based phylogeny indicated that CHSLs had diverse evolutionary patterns. STS, ACS, and 2-PS clustered with CHSs from the same species (late diverged pattern), while CTAS, BBS, BPS, and BIS were distant from their CHS homologs (early diverged pattern). The amino-acid phylogeny suggested that CHS and CHSL proteins formed clades according to enzyme function. The CHSs and CHSLs from Polygonaceae and Arachis had unique evolutionary histories. Synonymous mutation rates were lower in late diverged CHSLs than in early diverged ones, indicating that gene duplications occurred more recently in late diverged CHSLs than in early diverged ones. Relative rate tests proved that late diverged CHSLs had unequal rates to CHSs from the same species when using fatty acid synthase, which evolved from the common ancestor with the CHS superfamily, as the outgroup, while the early diverged lineages had equal rates. This indicated that late diverged CHSLs experienced more frequent mutation than early diverged CHSLs after gene duplication, allowing obtaining new functions in relatively short period of time.

  16. Therapeutic potential of bryophytes and derived compounds against cancer

    Institute of Scientific and Technical Information of China (English)

    Abhijit Dey; Anuradha Mukherjee

    2015-01-01

    Bryophytes, taxonomically placed between the algae and the pteridophytes, are divided into three classes such as Liverworts, Hornworts and Mosses. Indigenous use involves this small group of plants to treat various diseases. Bryophytes have been investigated pharmacologically for active biomolecules. Several constituents with therapeutic potential have been isolated, characterized and investigated for antibacterial, antifungal, antiviral, antioxidative, antiinflamatory and anticancerous efficacy. The present review deals with the literature covering the anticancerous potential of bryophytes. Apart from the examples of the compounds and the containing bryophyte genera, the authors have tried to include the examples of cancer cell lines on which the efficacy have been tested and the mode of action of certain cytotoxic agents. Crude extracts and isolated compounds from bryophytes were found to possess potent cytotoxic properties. Different types of terpenoids and bibenzyls have been reported among the most potent cytotoxic compounds. Most of these compounds were found to induce apoptosis by activating a number of genes and enzymes. Biochemical markers such as DNA fragmentation, nuclear condensation, proteolysis of poly (ADP-ribose) polymerase, activation of caspases, inhibition of antiapoptotic nuclear transcriptional factor-kappaB, activation of p38 mitogen-activated protein kinase etc. have been found to be associated with apoptotic and necrotic response. This review summarizes recent scientific findings and suggests further investigations to evaluate the cytotoxic efficacy of bryophytes.

  17. Advances in Studies on Chemical Constituents and Antimicrobial Activity of Bryophytes%苔藓植物化学成分及抑菌作用的研究进展

    Institute of Scientific and Technical Information of China (English)

    余治锦; 姜山

    2012-01-01

    苔藓植物是没有维管束的陆生植物,分为藓纲、苔纲和角苔纲3类。近年来的研究表明,苔藓植物能产生萜类、黄酮类及联苄类等生物活性物质,其中许多对病原真菌和细菌具有良好的抑制作用,是天然抗菌药物的重要来源。本文主要介绍苔藓植物的化学组成及其抑菌作用的研究情况。%Including Musci, Hepaticae and Anthocerotae, bryophytes are members of the land plants without vascular. Bryophytes can produce a great variety of bioactive compounds such as terpenoids, flavonoids and bibenzyls, some of which have obviously antifungal and antibacterial activities and are vital sources of naturally antimicrobial drugs. Chemical constituents of bryophyte and its antimicrobial activity are summarized and discussed in this paper.

  18. Synthesis and characterization of Fe colloid catalysts in inverse micelle solutions

    Energy Technology Data Exchange (ETDEWEB)

    Martino, A.; Stoker, M.; Hicks, M. [Sandia National Lab., Alburquerque, NM (United States)] [and others

    1995-12-31

    Surfactant molecules, possessing a hydrophilic head group and a hydrophobic tail group, aggregate in various solvents to form structured solutions. In two component mixtures of surfactant and organic solvents (e.g., toluene and alkanes), surfactants aggregate to form inverse micelles. Here, the hydrophilic head groups shield themselves by forming a polar core, and the hydrophobic tails groups are free to move about in the surrounding oleic phase. The formation of Fe clusters in inverse miscelles was studied.Iron salts are solubilized within the polar interior of inverse micelles, and the addition of the reducing agent LiBH{sub 4} initiates a chemical reduction to produce monodisperse, nanometer sized Fe based particles. The reaction sequence is sustained by material exchange between inverse micelles. The surfactant interface provides a spatial constraint on the reaction volume, and reactions carried out in these micro-heterogeneous solutions produce colloidal sized particles (10-100{Angstrom}) stabilized in solution against flocculation of surfactant. The clusters were stabilized with respect to size with transmission electron microscopy (TEM) and with respect to chemical composition with Mossbauer spectroscopy, electron diffraction, and x-ray photoelectron spectroscopy (XPS). In addition, these iron based clusters were tested for catalytic activity in a model hydrogenolysis reaction. The hydrogenolysis of naphthyl bibenzyl methane was used as a model for coal pyrolysis.

  19. Novel bimetallic dispersed catalysts for temperature-programmed coal liquefaction

    Energy Technology Data Exchange (ETDEWEB)

    Chunshan, Song; Kirby, S.; Schmidt, E. [Pennsylvania State Univ., University Park, PA (United States)] [and others

    1995-12-31

    The objective of this project is to explore bimetallic dispersed catalysts for more efficient coal liquefaction. Coal liquefaction involves cleavage of methylene, dimethylene and ether bridges connecting various aromatic units and the reactions of various oxygen functional groups. This paper describes recent results on (1) hydrodeoxygenation of O-containing polycyclic model compounds using novel organometallic catalyst precursors; and (2) activity and selectivity of dispersed Fe catalysts from organometallic and inorganic precursors for hydrocracking of 4-(1-naphthylmethyl) bibenzyl. The results showed that some iron containing catalysts have higher activity in the sulfur-free form, contrary to conventional wisdom. Adding sulfur to Fe precursors with Cp-ligands decreased the activity of the resulting catalyst. This is in distinct contrast to the cases with iron pentacarbonyl and superfine Fe{sub 2}O{sub 3}, where S addition increased their catalytic activity substantially. A positive correlation between sulfur addition and increased activity can be seen, but a reversed trend between Fe cluster size and hydrocracking conversion could be observed, for carbonyl-type Fe precursors. It is apparent that the activity and selectivity of Fe catalysts for NMBB conversion depends strongly on both the type of ligand environment, the oxidation state and the number of intermetal bonds in the molecular precursor.

  20. Bond cleavage reactions of the bridge structure in coal in the presence of hydrogen donating compounds; Suiso kyoyosei kagobutsu sonzaika deno sekitanchu no kakyo kozo no kairetsu hanno

    Energy Technology Data Exchange (ETDEWEB)

    Bando, N.; Kidena, K.; Murata, S.; Nomura, M. [Osaka University, Osaka (Japan). Faculty of Engineering

    1996-10-28

    In this paper, bond cleavage reactions are discussed in relation to the softening and solubilization of coal. Were used 9,10-dihydroanthracene (DHA) and 9,10-dihydrophenanthrene (DHP) as models of hydrogen donating compounds in coal, and bibenzyl, 1,2-diethane, benzylphenylether, and 1,5-dibenzylnaphthalene were used as models of bridge structure compounds. They were compared mutually, as to reactivity of coal against DHA and DHP. For the homolytic cleavage of bridges, DHA with excellent radical supplement performance provided excellent hydrogen donating performance. While, for the ipso-position cleavage of bridges, it was found that DHP can act as an effective hydrogen donor. For the reaction between coal and hydrogenated aromatic compounds, cleavage of relatively weak bonds, such as ether linkage and dimethylene linkage, occurred at about 380{degree}C, and hydrogen from DHA or DHP was consumed. On the other hand, the results suggested that the cleavage reaction at ipso-position affected by hydrogen donating solvent is also important at temperature range around 420{degree}C. 2 refs., 3 figs., 1 tab.

  1. Polycyclic aromatic hydrocarbon (PAH) formation from benzyl radicals: a reaction kinetics study.

    Science.gov (United States)

    Sinha, Sourab; Raj, Abhijeet

    2016-03-21

    The role of resonantly stabilized radicals such as propargyl, cyclopentadienyl and benzyl in the formation of aromatic hydrocarbons such as benzene and naphthalene in the high temperature environments has been long known. In this work, the possibility of benzyl recombination to form three-ring aromatics, phenanthrene and anthracene, is explored. A reaction mechanism for it is developed, where reaction energetics are calculated using density functional theory (B3LYP functional with 6-311++G(d,p) basis set) and CBS-QB3, while temperature-dependent reaction kinetics are evaluated using transition state theory. The mechanism begins with barrierless formation of bibenzyl from two benzyl radicals with the release of 283.2 kJ mol(-1) of reaction energy. The further reactions involve H-abstraction by a H atom, H-desorption, H-migration, and ring closure to gain aromaticity. Through mechanism and rate of production analyses, the important reactions leading to phenanthrene and anthracene formation are determined. Phenanthrene is found to be the major product at high temperatures. Premixed laminar flame simulations are carried out by including the proposed reactions for phenanthrene formation from benzyl radicals and compared to experimentally observed species profiles to understand their effects on species concentrations.

  2. Superacid Catalyzed Coal Conversion Chemistry. 1st and 2nd Quarterly Technical Progress Reports, September 1, 1983-March 30, 1984.

    Science.gov (United States)

    Olah, G. A.

    1984-01-01

    In our laboratories we have previously developed a mild coal conversion process. This involves the use of a superacid system consisting of HF and BF{sub 3} in presence of hydrogen and/or a hydrogen donor solvent. In order to understand the chemistry involved in the process of depolymerization of coal by the HF:BF{sub 3}:H{sub 2} system we are carrying out a systematic study of a number of coal model compounds. The model compounds selected for present study have two benzene rings connected with various bridging units such as alkylidene, ether, sulfide etc. From studies so far carried out it appears that high pyridine extractibilities achieved by treating coal at temperature below 100 degrees C results from the cleavage of bridges such as present in bibenzyl, diphenyl methane, dibenzyl ether, dibenzyl sulfide etc. On the other hand the increased cyclohexane extractibility and distillability observed at relatively higher temperatures and hydrogen pressures reflects the hydrogenation and cleavage of the aromatic backbone in coal structure similar to what is seen in the conversion of model compounds such as biphenyl, diphenyl ether, diphenyl sulfide, anthracene, etc.

  3. Novel bimetallic dispersed catalysts for temperature-programmed coal liquefaction. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Chunshan Song; Schobert, H.H.; Parfitt, D.P. [and others

    1997-11-01

    Development of new catalysts is a promising approach to more efficient coal liquefaction. It has been recognized that dispersed catalysts are superior to supported catalysts for primary liquefaction of coals, because the control of initial coal dissolution or depolymerization requires intimate contact between the catalyst and coal. This research is a fundamental and exploratory study on catalytic coal liquefaction, with the emphasis on exploring novel bimetallic dispersed catalysts for coal liquefaction and the effectiveness of temperature-programmed liquefaction using dispersed catalysts. The primary objective of this research was to explore novel bimetallic dispersed catalysts from organometallic molecular precursors, that could be used in low concentrations but exhibit relatively high activity for efficient hydroliquefaction of coals under temperature-programmed conditions. We have synthesized and tested various catalyst precursors in liquefaction of subbituminous and bituminous coals and in model compound studies to examine how do the composition and structure of the catalytic precursors affect their effectiveness for coal liquefaction under different reaction conditions, and how do these factors affect their catalytic functions for hydrogenation of polyaromatic hydrocarbons, for cleavage of C-C bonds in polycyclic systems such as 4-(1-naphthylmethyl)bibenzyl, for hydrogenolysis of C-O bond such as that in dinaphthylether, for hydrodeoxygenation of phenolic compounds and other oxygen-containing compounds such as xanthene, and for hydrodesulfurization of polycyclic sulfur compounds such as dibenzothiophene. The novel bimetallic and monometallic precursors synthesized and tested in this project include various Mo- and Fe-based compounds.

  4. Bisbibenzyls, a new type of antifungal agent, inhibit morphogenesis switch and biofilm formation through upregulation of DPP3 in Candida albicans.

    Directory of Open Access Journals (Sweden)

    Li Zhang

    Full Text Available The yeast-to-hypha transition plays a crucial role in the pathogenesis of C. albicans. Farnesol, a quorum sensing molecule (QSM secreted by the fungal itself, could prevent the formation of hyphae and subsequently lead to the defect of biofilm formation. The DPP3, encoding phosphatase, is a key gene in regulating farnesol synthesis. In this study, we screened 24 bisbibenzyls and 2 bibenzyls that were isolated from bryophytes or chemically synthesized by using CLSI method for antifungal effect. Seven bisbibenzyls were found to have antifungal effects with IC(80 less than 32 µg/ml, and among them, plagiochin F, isoriccardin C and BS-34 were found to inhibit the hyphae and biofilm formation of C. albicans in a dose-dependent manner. To uncover the underlying relationship between morphogenesis switch and QSM formation, we measured the farnesol production by HPLC-MS and quantified Dpp3 expression by detecting the fluorescent intensity of green fluorescent protein tagged strain using Confocal Laser Scanning microscopy and Multifunction Microplate Reader. The DPP3 transcripts were determined by real-time PCR. The data indicated that the bisbibenzyls exerted antifungal effects through stimulating the synthesis of farnesol via upregulation of Dpp3, suggesting a potential antifungal application of bisbibenzyls. In addition, our assay provides a novel, visual and convenient method to measure active compounds against morphogenesis switch.

  5. 构树叶中的细胞毒成分%Cytotoxic constituents from the leaves of Broussonetia papyrifera

    Institute of Scientific and Technical Information of China (English)

    冉小库; 王晓彤; 刘培培; 迟玉新; 王博佳; 窦德强; 康廷国; 熊伟

    2013-01-01

    目的:研究构树叶的化学成分.方法:采用D101型大孔吸附树脂、硅胶、ODS和半制备型高效液相色谱等分离方法对构树叶提取物分离纯化,通过1D,2D NMR技术确定其结构,并采用MTT法对分得化合物进行细胞毒活性测定,同时比色法和采用高效液相色谱法建立了对构树叶中总黄酮和cosmosiin的含量测定方法.结果:分离鉴定了6个化合物,它们的结构鉴定为:(+)-pinoresinol-4'-O-β-D-glucopyransyl-4”-O-β-D-apiofuranoside (1),cosmosiin (2),luteolin-7-O-β-D-glucopyranoside (3),liriodendrin(4),3,5,4'-trihydroxy-bibenzyl-3-O-β-D-glucoside (5),apigenin-6-C-β-D-glycopyranside (6).结论:化合物1为一个新的木脂素,化合物5,6为首次从该属植物中分离,化合物1,4,6对HepG-2细胞株有不同程度的抑制活性,而化合物2,3,5对HepG-2细胞株没有活性;根据含量测定结果得知,确定构树叶的最佳采收时间为9月份.%AIM:To investigate the chemical constituents from the leaves of Broussonetia papyrifera.METHODS:The chemical constituents were isolated and purified by macroporous adsorptive resin D101,silica gel,and ODS column chromatography and preparative HPLC.Their structures were elucidated on the basis of 1D and 2D NMR analyses.In addition,their cytotoxic activity against human hepatoma carcinoma cells (HepG-2) were evaluated by the MTT method.Furthermore,RP-HPLC and colorimetric methods were used for the analysis of cosmosiin and total flavonoids.RESULTS:A new lignan,together with five known compounds were obtained,and their structures were characterized as (+)-pinoresinol-4'-O-β-D-glucopyranosyl-4"-O-β-D-apiofuranoside (1),cosmosiin (2),luteolin-7-O-β-D-glucopyranoside (3),liriodendrin (4),3,5,4'-trihydroxy-bibenzyl-3-O-β-D-glucoside (5),and apigenin-6-C-β-Dglucopyranside (6).Furthermore,RP-HPLC and colorimetric methods were established for the analysis of cosmosiin and total flavonoids.CONCLUSION:Compound 1 was a new lignan

  6. Kinetics assisted design of catalysts for coal liquefaction. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Klein, M.T.; Foley, H.C.; Calkins, W.H.; Scouten, C.

    1998-02-01

    The thermal and catalytic reactions of 4-(1-naphthylmethyl)bibenzyl (NBBM), a resid and coal model compound, were examined. Catalytic reaction of NBBM was carried out at 400 C under hydrogen with a series of transition metal-based catalytic materials including Fe(CO){sub 4}PPh{sub 3}, Fe(CO){sub 3}(PPh{sub 3}){sub 2}, Fe(CO){sub 2}(PPh{sub 3}){sub 2}CS{sub 2}, Fe(CO){sub 5}, Mo(CO){sub 6}, Mn{sub 2}(CO){sub 10}, Fe{sub 2}O{sub 3} and MoS{sub 2}. Experimental findings and derived mechanistic insights were organized into molecular-level reaction models for NBBM pyrolysis and catalysis. Hydropyrolysis and catalysis reaction families occurring during NBBM hydropyrolysis at 420 C were summarized in the form of reaction matrices which, upon exhaustive application to the components of the reacting system, yielded the mechanistic reaction model. Each reaction family also had an associated linear free energy relationship (LFER) which provided an estimate of the rate constant k{sub i} given a structural property of species i or its reaction. Including the catalytic reaction matrices with those for the pyrolysis model provided a comprehensive NBBM catalytic reaction model and allowed regression of fundamental LFER parameters for the catalytic reaction families. The model also allowed specification of the property of an optimal catalyst. Iron, molybdenum and palladium were predicted to be most effective for model compound consumption. Due to the low costs associated with iron and its disposal, it is a good choice for coal liquefaction catalysis and the challenge remains to synthesize small particles able to access the full surface area of the coal macromolecule.

  7. 构树叶中的细胞毒成分(英文)

    Institute of Scientific and Technical Information of China (English)

    冉小库; 王晓彤; 刘培培; 迟玉新; 王博佳; 窦德强; 康廷国; 熊伟

    2013-01-01

    目的:研究构树叶的化学成分。方法:采用D101型大孔吸附树脂、硅胶、ODS和半制备型高效液相色谱等分离方法对构树叶提取物分离纯化,通过1D,2DNMR技术确定其结构,并采用MTT法对分得化合物进行细胞毒活性测定,同时比色法和采用高效液相色谱法建立了对构树叶中总黄酮和cosmosiin的含量测定方法。结果:分离鉴定了6个化合物,它们的结构鉴定为:(+)-pinoresinol-4′-O-β-D-glucopyransyl-4″-O-β-D-apiofuranoside(1),cosmosiin(2),luteolin-7-O-β-D-glucopyranoside(3),liriodendrin(4),3,5,4′-trihydroxy-bibenzyl-3-O-β-D-glucoside(5),apigenin-6-C-β-D-glycopyranside(6)。结论:化合物1为一个新的木脂素,化合物5,6为首次从该属植物中分离,化合物1,4,6对HepG-2细胞株有不同程度的抑制活性,而化合物2,3,5对HepG-2细胞株没有活性;根据含量测定结果得知,确定构树叶的最佳采收时间为9月份。

  8. Moscatilin induces apoptosis of pancreatic cancer cells via reactive oxygen species and the JNK/SAPK pathway

    Science.gov (United States)

    Zhang, Lei; Fang, Yuan; Xu, Xue-Feng; Jin, Da-Yong

    2017-01-01

    Moscatilin is a bibenzyl derivative extracted from the Dendrobium aurantiacum var. denneanum, which has traditionally been used as an immunomodulatory treatment in China. The present study was designed to determine whether moscatilin is a pro-apoptotic agent in pancreatic cancer, and to elucidate the underlying mechanisms. The apoptotic and anti-proliferative effects of moscatilin on pancreatic cancer cells were determined in vitro using biochemical assays, such as the MTT assay, colony formation assay, Hoechst staining and DNA fragmentation assay, and in vivo using Panc-1 pancreatic cancer xenografts. Western blotting was also conducted to evaluate the expression levels of B-cell lymphoma 2 (Bcl2), Bcl2-associated X protein (Bax), Bcl2 homologous antagonist killer (Bak), caspase 3, cleaved-caspase 3, poly (ADP-ribose) polymerase, p-c-Jun N-terminal kinase (JNK)/stress-activated protein kinases (SAPK) and JNK/SAPK in response to moscatilin. We used DCFH-DA to detect the production of reactive oxygen species (ROS) induced by moscatilin. The present study demonstrated that moscatilin markedly inhibited pancreatic cancer cell viability and induced cell apoptosis in a concentration-dependent manner. Conversely, moscatilin did not affect the cell viability of human umbilical vein endothelial cells at the comparable dosage. Treatment with moscatilin suppressed clonogenicity of Panc-1 cells in a concentration-dependent manner. Furthermore, a decrease in Bcl2 expression, and an increase in the expression levels of Bak and Bax, was detected following treatment with moscatilin, resulting in an increase in the proapoptotic/anti-apoptotic expression ratio (Bax/Bcl2) in Panc-1 cells. Moscatilin also induced activation of the caspase-dependent mitochondrial apoptotic pathway. In addition, moscatilin enhanced cellular ROS production and induced activation of JNKSAPK signaling pathway. Conversely, pretreatment with the ROS scavenger N-acetylcysteine or the JNK

  9. Progress in the studies on chemical constituents and anti-tumor effects of polytrichum spp%金发藓属化学成分及抗肿瘤作用研究进展

    Institute of Scientific and Technical Information of China (English)

    成晓霞; 张志琪; 肖娅萍; 刘全宏

    2014-01-01

    The recent advances in the study on chemical constituents,pharmacological activities and anti-tumor mechanism of Polytrichum spp.are reviewed.A series of new compounds with novel skeletons and significant bioactivities have been obtained from Polytrichum spp. For example,1 1 new benzonaphthoxanthenones with novel polycyclic skeleton,2 unusual flavonones coupled with styryl units and 2 novel cinnamoyl bibenzyls from the moss Polytrichum commune L.ex Hedw, Polytrichum ohioense Ren&Card and Polytrichum pallidisetum Funck, respectively.These compounds exhibited cytotoxicity against several kinds of tumor cells in vitro,including human lung carcinoma (A-549),human hepatoma carcinoma (HepG2),human breast adenocarcinoma (MCF-7 & MDA-MB-435),huamn bowel carcinoma (LOVO),human colon adenocarcinoma (HT-29 ), Human melanoma (RPMI-7951 ) and human glioblastoma multiforme (U-251).Moreover,these new compounds also can significantly inhibit the growth of leukaemia cells (6T-CEM human T cell leukemia,9PS murine P388 leukemia and L1210 murine lymphocytic leukemia ). Studies demonstrated that mitochondria dysfunction, excessive accumulation of active oxygen radicals,cell cycle arrest,cell membrane inj ury and cell apoptosis-inducing are the possible underlying anti-tumor mechanisms. Further studies are needed to confirm the chemical structure-antitumor activity relationship, drug metabolism, anti-tumor effects and precise mechanism not only in vitro but in vivo.%从金发藓的化学成分、抗肿瘤活性和抑癌机制等方面对国内外金发藓属植物研究的现状进行了综述.已有研究表明,在金发藓属(Polytrichum spp.)植物中分离得到苯并萘并呫吨酮类化合物及其衍生物、苯乙烯醛基并联苄化合物和苯乙烯基并二氢黄酮类化合物等具有新颖结构骨架的化合物,药理活性分析显示这些新化合物对体外培养的多种肿瘤细胞(如:A-549人肺癌细胞、HepG2人肝癌细胞、MCF-7人乳腺