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Sample records for bibenzyl

  1. Antioxidant Bibenzyl Derivatives from Notholaena nivea Desv.

    Directory of Open Access Journals (Sweden)

    Paola Montoro

    2011-03-01

    Full Text Available Four new bibenzyl derivatives were isolated, together with other known bibenzyls, by bioassay-guided fractionation of a CHCl3-MeOH extract of Notholaena nivea Desv. (Pteridaceae aerial parts. The structures were elucidated by NMR, ESIMS and other spectral analyses. Their antioxidative effects towards superoxide, lipidic peroxidation and the 2,2'-azino-bis-3-ethilbenzothiazoline-6-sulfonic acid (ABTS radical were assayed. Results showed that the compound 3,12-dihydroxy-5-methoxybibenzyl (6 is the most active compound in the ABTS free-radical scavenging test, while in the coupled oxidation of β-carotene and linoleic acid assay the compound 5,12-dihydroxy-3-methoxydibenzyl-6-carboxylic acid (1 exerted the highest activity after 1h. A superoxide anion enzymatic test was also carried out and the results were confirmed by an inhibition of xanthine oxidase activity assay. The putative protective role played by compounds 1 and 6 on the injurious effects of reactive oxygen metabolites on the intestinal epithelium, using a Caco-2 human cell line, was investigated. H2O2-induced alterations were prevented by preincubating the cells with compounds 1 and 6.

  2. Cytotoxic bibenzyl dimers from the stems of Dendrobium fimbriatum Hook.

    Science.gov (United States)

    Xu, Feng-Qing; Xu, Fang-Cheng; Hou, Bo; Fan, Wei-Wei; Zi, Cheng-Ting; Li, Yan; Dong, Fa-Wu; Liu, Yu-Qing; Sheng, Jun; Zuo, Zhi-Li; Hu, Jiang-Miao

    2014-11-15

    The bioassay-guided chemical investigation of the stems of Dendrobium fimbriatum Hook led to the isolation of seven first reported bibenzyl dimers with a linkage of a methylene moiety, fimbriadimerbibenzyls A-G (1-7), together with a new dihydrophenanthrene derivative (S)-2,4,5,9-tetrahydroxy-9,10-dihydrophenanthrene (8) and thirteen known compounds (9-21). The structure of the new compound was established by spectroscopic analysis. Biological evaluation of bibenzyl derivatives against five human cell lines indicated that seven of those compounds exhibited broad-spectrum and cytotoxic activities with IC50 values ranging from 2.2 to 21.2 μM. Those rare bibenzyl dimers exhibited cytotoxic activities in vitro and the cytotoxicity decreased as the number of oxygen-containing groups in the structure decreases. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Activity-guided isolation of cytotoxic bis-bibenzyl constituents from Dumortiera hirsuta.

    Science.gov (United States)

    Toyota, Masao; Ikeda, Risa; Kenmoku, Hiromichi; Asakawa, Yoshinori

    2013-01-01

    Activity-guided fractionation of the ether extract of Dumortiera hirsute (Japanese liverwort), using cytotoxicity testing with cultured HL 60 and KB cells, resulted in the isolation of a new cytotoxic bis-bibenzyl compound, along with the two known bis-bibenzyls: isomarchantin C and isoriccardin C. The structural determination of the new bis-bibenzyl through extensive NMR spectral data indicated a derivative of marchantin A, which has been isolated from the liverwort Marchantia polymorpha. The cytotoxicity of the bis-bibenzyls was evaluated by the MTT (3-(4,5-di-methylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay using cultured HL 60 and KB cells.

  4. Phytotoxic activity of bibenzyl derivatives from the orchid Epidendrum rigidum.

    Science.gov (United States)

    Hernández-Romero, Yanet; Acevedo, Laura; Sánchez, María de los Angeles; Shier, W Thomas; Abbas, Hamed K; Mata, Rachel

    2005-08-10

    A whole plant chloroform-methanol extract of the orchid Epidendrum rigidum inhibited radicle growth of Amaranthus hypochondriacus seedlings (IC50 = 300 microg/mL). Bioassay-guided fractionation furnished four phytotoxins, namely, gigantol (1), batatasin III (2), 2,3-dimethoxy-9,10-dihydrophenathrene-4,7-diol (9), and 3,4,9-trimethoxyphenanthrene-2,5-diol (11), along with the known flavonoids apigenin, vitexin, and isovetin and the triterterpenoids 24,24-dimethyl-9,19-cyclolanostane-25-en-3beta-ol (14) and 24-methyl-9,19-cyclolanostane-25-en-3beta-ol (15). Stilbenoids 1, 2, 9, and 11 inhibited radicle growth of A. hypochondriacus with IC50 values of 0.65, 0.1, 0.12, and 5.9 microM, respectively. Foliar application of gigantol (1) at 1 microM to 4 week old seedlings of A. hypochondriacus reduced shoot elongation by 69% and fresh weight accumulation by 54%. Bibenzyls 1 and 2, as well as synthetic analogues 4'-hydroxy-3,3',5-trimethoxybibenzyl (3), 3,3',4',5-tetramethoxybibenzyl (4), 3,4'-dihydroxy-5-methoxybibenzyl (5), 3'-O-methylbatatasin III (6), 3,3',5-trihydroxybibenzyl (7), and 3,4',5-trihydroxybibenzyl (8), were tested for phytotoxicity in axenic cultures of the small aquatic plant Lemna pausicostata. All bibenzyls derivatives except 7 and 8 inhibited growth and increased cellular leakage with IC50 values of 89.9-180 and 89.9-166 microM, respectively. The natural and synthetic bibenzyls showed marginal cytotoxicity on animal cells. The results suggest that orchid bibenzyls may be good lead compounds for the development of novel herbicidal agents.

  5. 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.

  6. New Cytotoxic Bibenzyl and Other Constituents from Bauhinia ungulata L. (Fabaceae).

    Science.gov (United States)

    de Sousa, Leôncio M; de Carvalho, Jarbas L; da Silva, Horlando C; Lemos, Telma L G; Arriaga, Angela M C; Braz-Filho, Raimundo; Militão, Gardênia C G; Silva, Thiago D S; Ribeiro, Paulo R V; Santiago, Gilvandete M P

    2016-12-01

    A new bibenzyl, 2'-hydroxy-3,5-dimethoxy-4-methylbibenzyl (1) and four known compounds identified as 2'-hydroxy-3,5-dimethoxybibenzyl (2), liquiritigenin (3), guibourtinidol (4) and fisetinidol (5) were isolated from the roots of Bauhinia ungulata L. Phytochemical investigations of the stems of B. ungulata led to the isolation of the known compounds identified as liquiritigenin (3), guibourtinidol (4), fisetinidol (5), taraxerol (6), betulinic acid (7), taraxerone (8), glutinol (9), a mixture of sitosterol (10) and stigmasterol (11), pacharin (12), naringenin (13) and eriodictyol (14). The structures of these compounds were elucidated on the basis of their spectral data (IR, MS, 1D- and 2D-NMR). The cytotoxicity of the bibenzyl 1 has been evaluated against four human cancer cell lines, showing the IC 50 values of 4.3 and 6.5 μg ml -1 against pro-myelocytic leukemia (HL-60) and cervical adenocarcinoma (HEP-2) cell lines, respectively. This article also registers for the first time the 13 C-NMR data of the known bibenzyl 2. © 2016 Wiley-VHCA AG, Zurich, Switzerland.

  7. Aglaiabbrevins A-D, New Prenylated Bibenzyls from the Leaves of Aglaia abbreviata with Potent PTP1B Inhibitory Activity.

    Science.gov (United States)

    Sun, Pan; Jiang, Chang-Sheng; Zhang, Yi; Liu, Ai-Hong; Liang, Tong-Jun; Li, Jia; Guo, Yue-Wei; Jiang, Jian-Mei; Mao, Shui-Chun; Wang, Bin

    2017-01-01

    Four new prenylated bibenzyls, named aglaiabbrevins A-D (2, 4-6), were isolated from the leaves of Aglaia abbreviata, along with two known related analogues, 3,5-dihydroxy-2-[3,7-dimethyl-2(E),6-octadienyl]bibenzyl (7) and 3,5-dihydroxy-2-(3-methyl-2-butenyl)bibenzyl (8). The structures of the new compounds were elucidated on the basis of extensive spectroscopic experiments, mainly one and two dimensional (1D- and 2D)-NMR, and the absolute configuration of 5 was determined by the measurement of specific rotation. The isolated compounds were evaluated for their protein tyrosine phosphatase-1B (PTP1B) inhibitory activity. The results showed that compounds 5-7 exhibited more potent PTP1B inhibitory effects with IC 50 values of 2.58±0.52, 2.44±0.35, and 2.23±0.14 µM, respectively, than the positive control oleanolic acid (IC 50 =2.74±0.20 µM). On the basis of the data obtained, these bibenzyls with the longer C-2 prenyl groups may be considered as potential lead compounds for the development of new anti-obesity and anti-diabetic agents. Also, the PTP1B inhibitory effects for prenylated bibenzyls are being reported for the first time.

  8. The Bibenzyl Canniprene Inhibits the Production of Pro-Inflammatory Eicosanoids and Selectively Accumulates in Some Cannabis sativa Strains.

    Science.gov (United States)

    Allegrone, Gianna; Pollastro, Federica; Magagnini, Gianmaria; Taglialatela-Scafati, Orazio; Seegers, Julia; Koeberle, Andreas; Werz, Oliver; Appendino, Giovanni

    2017-03-24

    Canniprene (1), an isoprenylated bibenzyl unique to Cannabis sativa, can be vaporized and therefore potentially inhaled from marijuana. Canniprene (1) potently inhibited the production of inflammatory eicosanoids via the 5-lipoxygenase pathway (IC 50 0.4 μM) and also affected the generation of prostaglandins via the cyclooxygenase/microsomal prostaglandin E 2 synthase pathway (IC 50 10 μM), while the related spiranoid bibenzyls cannabispiranol (2) and cannabispirenone (3) were almost inactive in these bioassays. The concentration of canniprene (1) was investigated in the leaves of 160 strains of C. sativa, showing wide variations, from traces to >0.2%, but no correlation was found between its accumulation and a specific phytocannabinoid profile.

  9. Discrimination of the rare medicinal plant Dendrobium officinale based on naringenin, bibenzyl, and polysaccharides.

    Science.gov (United States)

    Chen, Xiaomei; Wang, Fangfei; Wang, Yunqiang; Li, Xuelan; Wang, Airong; Wang, Chunlan; Guo, Shunxing

    2012-12-01

    The aim of this study was to establish a method for discriminating Dendrobium officinale from four of its close relatives Dendrobium chrysanthum, Dendrobium crystallinum, Dendrobium aphyllum and Dendrobium devonianum based on chemical composition analysis. We analyzed 62 samples of 24 Dendrobium species. High performance liquid chromatography analysis confirmed that the four low molecular weight compounds 4',5,7-trihydroxyflavanone (naringenin), 3,4-dihydroxy-4',5-dime-thoxybibenzyl (DDB-2), 3',4-dihydroxy-3,5'-dimethoxybibenzyl (gigantol), and 4,4'-dihydroxy-3,3',5-trimethoxybibenzy (moscatilin), were common in the genus. The phenol-sulfuric acid method was used to quantify polysaccharides, and the monosaccharide composition of the polysaccharides was determined by gas chromatography. Stepwise discriminant analysis was used to differentiate among the five closely related species based on the chemical composition analysis. This proved to be a simple and accurate approach for discriminating among these species. The results also showed that the polysaccharide content, the amounts of the four low molecular weight compounds, and the mannose to glucose ratio, were important factors for species discriminant. Therefore, we propose that a chemical analysis based on quantification of naringenin, bibenzyl, and polysaccharides is effective for identifying D. officinale.

  10. Relative light yield and temporal response of a stilbene-doped bibenzyl organic scintillator for neutron detection

    Energy Technology Data Exchange (ETDEWEB)

    Brown, J. A.; Goldblum, B. L., E-mail: bethany@nuc.berkeley.edu; Brickner, N. M.; Daub, B. H.; Kaufman, G. S.; Bibber, K. van; Vujic, J. [Department of Nuclear Engineering, University of California, Berkeley, California 94720 (United States); Bernstein, L. A.; Bleuel, D. L.; Caggiano, J. A.; Hatarik, R.; Phillips, T. W.; Zaitseva, N. P. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Wender, S. A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2014-05-21

    The neutron time-of-flight (nTOF) diagnostics used to characterize implosions at the National Ignition Facility (NIF) has necessitated the development of novel scintillators that exhibit a rapid temporal response and high light yield. One such material, a bibenzyl-stilbene mixed single-crystal organic scintillator grown in a 99.5:0.5 ratio in solution, has become the standard scintillator used for nTOF diagnostics at NIF. The prompt fluorescence lifetime and relative light yield as a function of proton energy were determined to calibrate this material as a neutron detector. The temporal evolution of the intensity of the prompt fluorescent response was modeled using first-order reaction kinetics and the prompt fluorescence decay constant was determined to be 2.46 ± 0.01 (fit) ± 0.13 (systematic) ns. The relative response of the bibenzyl-stilbene mixed crystal generated by recoiling protons was measured, and results were analyzed using Birks' relation to quantify the non-radiative quenching of excitation energy in the scintillator.

  11. 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.

  12. Chrysotoxine, a novel bibenzyl compound selectively antagonizes MPP⁺, but not rotenone, neurotoxicity in dopaminergic SH-SY5Y cells.

    Science.gov (United States)

    Song, Ju-Xian; Shaw, Pang-Chui; Wong, Ngok-Shun; Sze, Cho-Wing; Yao, Xin-Sheng; Tang, Chi-Wai; Tong, Yao; Zhang, Yan-Bo

    2012-07-11

    Chrysotoxine is a naturally occurring bibenzyl compound found in medicinal Dendrobium species. We previously reported that chrysotoxine structure-specifically suppressed 6-hydroxydopamine (6-OHDA)-induced dopaminergic cell death. Whether chrysotoxine and other structurally similar bibenzyl compounds could also inhibit the neurotoxicity of 1-methyl-4-phenyl pyridinium (MPP(+)) and rotenone has not been investigated. We showed herein that chrysotoxine inhibited MPP(+), but not rotenone, induced dopaminergic cell death in SH-SY5Y cells. The overproduction of reactive oxygen species (ROS), mitochondrial dysfunction as indexed by the decrease in membrane potential, increase in calcium concentration and NF-κB activation triggered by MPP(+) were blocked by chrysotoxine pretreatment. The imbalance between the pro-apoptotic signals (Bax, caspase-3, ERK and p38 MAPK) and the pro-survival signals (Akt/PI3K/GSK-3β) induced by MPP(+) was partially or totally rectified by chrysotoxine. The results indicated that ROS inhibition, mitochondria protection, NF-κB modulation and regulation of multiple signals determining cell survival and cell death were involved in the protective effects of chrysotoxine against MPP(+) toxicity in SH-SY5Y cells. Given the different toxic profiles of 6-OHDA and MPP(+) as compared to rotenone, our results also indicated that DAT inhibition may partially account for the neuroprotective effects of chrysotoxine. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  13. Dendrobium nobile Lindley and its bibenzyl component moscatilin are able to protect retinal cells from ischemia/hypoxia by dowregulating placental growth factor and upregulating Norrie disease protein.

    Science.gov (United States)

    Chao, Wen-Haur; Lai, Ming-Yi; Pan, Hwai-Tzong; Shiu, Huei-Wen; Chen, Mi-Mi; Chao, Hsiao-Ming

    2018-06-22

    Presumably, progression of developmental retinal vascular disorders is mainly driven by persistent ischemia/hypoxia. An investigation into vision-threatening retinal ischemia remains important. Our aim was to evaluate, in relation to retinal ischemia, protective effects and mechanisms of Dendrobium nobile Lindley (DNL) and its bibenzyl component moscatilin. The therapeutic mechanisms included evaluations of levels of placental growth factor (PLGF) and Norrie disease protein (NDP). An oxygen glucose deprivation (OGD) model involved cells cultured in DMEM containing 1% O 2 , 94% N 2 and 0 g/L glucose. High intraocular pressure (HIOP)-induced retinal ischemia was created by increasing IOP to 120 mmHg for 60 min in Wistar rats. The methods included electroretinogram (ERG), histopathology, MTT assay and biochemistry. When compared with cells cultured in DMEM containing DMSO (DMSO+DMEM), cells subjected to OGD and pre-administrated with DMSO (DMSO+OGD) showed a significant reduction in the cell viability and NDP expression. Moreover, cells that received OGD and 1 h pre-administration of 0.1 μM moscatilin (Pre-OGD Mos 0.1 μM) showed a significant counteraction of the OGD-induced decreased cell viability. Furthermore, compared with the DMSO+OGD group (44.54 ± 3.15%), there was significant elevated NDP levels in the Pre-OGD Mos 0.1 μM group (108.38 ± 29.33%). Additionally, there were significant ischemic alterations, namely reduced ERG b-wave, less numerous retinal ganglion cells, decreased inner retinal thickness, and reduced/enhanced amacrine's ChAT/Müller's GFAP or vimentin immunolabelings. Moreover, there were significantly increased protein levels of HIF-1α, VEGF, PKM2, RBP2 and, particularly, PLGF (pg/ml; Sham vs. Vehicle: 15.11 ± 1.58 vs. 39.53 ± 5.25). These ischemic effects were significantly altered when 1.0 g/Kg/day DNL (DNL1.0 + I/R or I/R+ DNL1.0) was applied before and/or after ischemia, but not vehicle (Vehicle+I/R). Of

  14. Isolation of Stilbenoids and Lignans from Dendrobium hongdie

    African Journals Online (AJOL)

    Chen YG, Xu JJ, Yu H, Qing C, Zhang YL, Wang LQ, Liu. Y, Wang JH. Cytotoxic phenolics from Bulbophyllum odoratissimum. Food Chem, 2008; 107: 169–173. 17. Hernández-Romero Y, Acevedo L, Sánchez MLÁ, Shier. WT, Abbas HK, Mata R. Phytotoxic activity of bibenzyl derivatives from the Orchid Epidendrum rigidum.

  15. Sesquiterpene amino ether and cytotoxic phenols from Dendrobium wardianum Warner.

    Science.gov (United States)

    Zhang, Cong; Liu, Shou-Jin; Yang, Liu; Yuan, Ming-Yan; Li, Jin-Yu; Hou, Bo; Li, Hong-Mei; Yang, Xing-Zhi; Ding, Chang-Chun; Hu, Jiang-Miao

    2017-10-01

    A new bibenzyl derivative, dendrocandin V (1) and a new sesquiterpene amino ether, wardianumine A (2), together with eleven known compounds, including phenanthrenes (denbinobin (3), 9,10-dihydro-denbinobin (4), mostatin (5), loddigesiinols A (6)), bibenzyls (moscatilin (7), 5-hydroxy-3,4'-dimethoxybibenzyl (8), 3,4-dihydroxy-5,4'-dimethoxy bibenzyl (9), dendrocandin A (10), gigantol (11), dendrocandin U (12)) and an alkaloids (dihydroshihunine, 13) were isolated from the EtOH extraction of stems of Dendrobium wardianum Warner. Isolation of the new compound 2 indicated that N,N-dimethylethanolamine as the key adduction in the synthesis of dendroxine and its analogs in Dendrobium species. The hypothetical biosynthetic pathway of 2 was then postulated. Inspired by literature and traditional usage of the herbal medicine, some compounds were sent for cytotoxic activity and the results indicated that compounds 1, 3, 4, 5 showed cytotoxic activities against five human cancer cell lines (HL-60, A-549, SMMC-7721, MCF-7, and SW-480) with IC50 from 2.33-38.48μM. Among those compounds, 3 and 4 showed cell line selectivity with strong activity comparable to DDP. Copyright © 2017. Published by Elsevier B.V.

  16. Coal-related research, organic chemistry, and catalysis

    International Nuclear Information System (INIS)

    Anon.

    1980-01-01

    Coal chemistry research topics included: H exchange at 400 0 C, breaking C-C bonds in coal, molecular weight estimation using small-angle neutron scattering, 13 C NMR spectra of coals, and tunneling during H/D isotope effects. Studies of coal conversion chemistry included thermolysis of bibenzyl and 1-naphthol, heating of coals in phenol, advanced indirect liquefaction based on Koelbel slurry Fischer-Tropsch reactor, and plasma oxidation of coal minerals. Reactions of PAHs in molten SbCl 3 , a hydrocracking catalyst, were studied. Finally, heterogeneous catalysis (desulfurization etc.) was studied using Cu, Au, and Ni surfaces. 7 figures, 6 tables

  17. Diazoalkane reduction for the synthesis of uranium hydrazonido complexes

    Energy Technology Data Exchange (ETDEWEB)

    Matson, Ellen M.; Fanwick, Phillip E.; Bart, Suzanne C. [Department of Chemistry, Purdue University, West Lafayette, IN (United States)

    2012-11-15

    The reactivity of the uranium(III) alkyl Tp*{sub 2}UCH{sub 2}Ph (1) toward diazoalkanes is reported. Addition of 1 equiv. N{sub 2}CPh{sub 2} produces 0.5 equiv. bibenzyl, along with Tp*{sub 2}U(N{sub 2}CPh{sub 2}) (2). This species is dynamic in solution at room temperature and rapidly interconverts between the η{sup 1}- and η{sup 2} isomers as determined by variable-temperature {sup 1}H NMR spectroscopy. X-ray crystallographic analysis at low temperature shows exclusively the η{sup 2} isomer, which features a short U-N multiple bond analogous to an imido species. The η{sup 1} isomer reacts quantitatively with aldehydes and ketones through multiple bond metathesis to produce Tp*{sub 2}U(O) and the corresponding ketazine. Treatment of 1 with N{sub 2}CHSiMe{sub 3} generates 0.5 equiv. bibenzyl and the η{sup 1} isomer Tp*{sub 2}U(N{sub 2}CHSiMe{sub 3}) (3). This species is unstable over the course of hours, and there is no spectroscopic evidence for the η{sup 2} isomer. Tp*{sub 2}U(η{sup 1}-N{sub 2}CHSiMe{sub 3}) can be trapped by addition of phenylacetylene by a [2+2] cycloaddition to afford the uranium(IV) metallacycle Tp*{sub 2}U[(N-N = CHSiMe{sub 3})CHCPh] (4). Crystallographic data for 4 are presented. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Therapeutic potential of bryophytes and derived compounds against cancer

    Directory of Open Access Journals (Sweden)

    Abhijit Dey

    2015-08-01

    Full Text Available 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.

  19. 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.

  20. Low temperature oxidation of benzene and toluene in mixture with n-decane.

    Science.gov (United States)

    Herbinet, Olivier; Husson, Benoit; Ferrari, Maude; Glaude, Pierre-Alexandre; Battin-Leclerc, Frédérique

    2013-01-01

    The oxidation of two blends, benzene/ n -decane and toluene/ n -decane, was studied in a jet-stirred reactor with gas chromatography analysis (temperatures from 500 to 1100 K, atmospheric pressure, stoichiometric mixtures). The studied hydrocarbon mixtures contained 75% of aromatics in order to highlight the chemistry of the low-temperature oxidation of these two aromatic compounds which have a very low reactivity compared to large alkanes. The difference of behavior between the two aromatic reactants is highly pronounced concerning the formation of derived aromatic products below 800 K. In the case of benzene, only phenol could be quantified. In the case of toluene, significant amounts of benzaldehyde, benzene, and cresols were also formed, as well as several heavy aromatic products such as bibenzyl, phenylbenzylether, methylphenylbenzylether, and ethylphenylphenol. A comparison with results obtained with neat n -decane showed that the reactivity of the alkane is inhibited by the presence of benzene and, to a larger extent, toluene. An improved model for the oxidation of toluene was developed based on recent theoretical studies of the elementary steps involved in the low-temperature chemistry of this molecule. Simulations using this model were successfully compared with the obtained experimental results.

  1. Coal/Polymer Coprocessing with Efficient Use of Hydrogen.

    Energy Technology Data Exchange (ETDEWEB)

    Broadbelt, L.J.

    1997-08-31

    The objective of the current research is to investigate the feasibility of coprocessing coal with waste polymers, with particular interest in employing the polymers as an alternate hydrogen source for coal upgrading and simultaneously recovering high valued fuels and chemicals from plastic waste. A chemical modeling approach was employed in which real and model feedstocks were used to identify the underlying reaction pathways, kinetics, and mechanisms controlling coal liquefaction in the presence of plastics and catalysts. Simple model systems were employed to facilitate product analysis and obtain information about the intrinsic reactivity. When reacted in binary mixtures, the conversion of tetradecane, a model compound of polyethylene, increased while the selectivities to primary products of 4-(naphthylmethyl) bibenzyl were enhanced. Experiments in the last six months in which the relative concentrations of the components were varied revealed that the effect was indeed a chemical one and not simply a result of dilution. An experimental protocol was developed to conduct experiments at elevated pressures more representative of coal liquefaction conditions. Preliminary experiments with real feedstocks allowed the extrinsic factors (i.e., diffusion limitations, solvent effects) to be identified. The combination of these two sets of experiments will ultimately be used to carry out process optimization and formulate strategies for catalyst development.

  2. 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.

  3. Mechanistic Investigation of Molybdate-Catalysed Transfer Hydrodeoxygenation.

    Science.gov (United States)

    Larsen, Daniel B; Petersen, Allan R; Dethlefsen, Johannes R; Teshome, Ayele; Fristrup, Peter

    2016-11-07

    The molybdate-catalysed transfer hydrodeoxygenation (HDO) of benzyl alcohol to toluene driven by oxidation of the solvent isopropyl alcohol to acetone has been investigated by using a combination of experimental and computational methods. A Hammett study that compared the relative rates for the transfer HDO of five para-substituted benzylic alcohols was carried out. Density-functional theory (DFT) calculations suggest a transition state with significant loss of aromaticity contributes to the lack of linearity observed in the Hammett study. The transfer HDO could also be carried out in neat PhCH 2 OH at 175 °C. Under these conditions, PhCH 2 OH underwent disproportionation to yield benzaldehyde, toluene, and significant amounts of bibenzyl. Isotopic-labelling experiments (using PhCH 2 OD and PhCD 2 OH) showed that incorporation of deuterium into the resultant toluene originated from the α position of benzyl alcohol, which is in line with the mechanism suggested by the DFT study. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Study on the structures and anti-hepatic fibrosis activity of stilbenoids from Arundina graminifolia (D. Don) Hochr.

    Science.gov (United States)

    Liu, Qingqing; Wang, Huiting; Lin, Fankai; Dai, Rongji; Yu, Deng lin; Lv, Fang

    2017-12-01

    A phytochemical study was performed on Arundina graminifolia (D.Don) Hochr. by silica gel column and semi-preparative HPLC, and ten stilbenoids were obtained. Their structures were elucidated by NMR and MS spectra and identified as 7-hydroxy-2,4-dimethoxy-9,10-dihydrophenanthrene (1), 4,7-dihydroxy-2-methoxy-9,10-dihydrophenanthrene (2), 2,7-dihydroxy-4-methoxy-9,10-dihydrophenanthrene (3), 3,3’-dihydroxy-5-methoxy-bibenzyl (4), 7-hydroxy-2,8-dimethoxy-phenanthrene-1,4-dione (5), 7-hydroxy-2,10-dimethoxy-phenanthre-ne-1,4-dione (6), 7-dihydroxy-2-methoxy-9,10-dihydrophenanthrene-1,4-dione (7), 7-hydroxy-2-methoxy-phenanthrene-1,4-dione (8), 7-hydroxy-1-(p-hydroxybenzyl)-2,4-dimethoxy-9,10-dihydroxy-phenanthrene (9), 2,7-dihydroxy-1-(p-hydroxybenzyl)-4-methoxy-9,10-dihydroxy-phenanthrene (10). Compounds 5 and 6 were isolated from this plant for the first time. The isolated compounds were examined for their anti-hepatic fibrosis activity against HSC-T6 cells in vitro. The results showed that compounds 4 and 5 exhibited moderate growth inhibitory effects with IC50 61.9 μg/mL and 52.7 μg/mL, respectively.

  5. 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.

  6. 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.

  7. 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.

  8. Gigantol Inhibits Epithelial to Mesenchymal Process in Human Lung Cancer Cells

    Directory of Open Access Journals (Sweden)

    Thitita Unahabhokha

    2016-01-01

    Full Text Available Lung cancer remains a leading public health problem as evidenced by its increasing death rate. The main cause of death in lung cancer patients is cancer metastasis. The metastatic behavior of lung cancer cells becomes enhanced when cancer cells undergo epithelial to mesenchymal transition (EMT. Gigantol, a bibenzyl compound extracted from the Thai orchid, Dendrobium draconis, has been shown to have promising therapeutic potential against cancer cells, which leads to the hypothesis that gigantol may be able to inhibit the fundamental EMT process in cancer cells. This study has demonstrated for the first time that gigantol possesses the ability to suppress EMT in non-small cell lung cancer H460 cells. Western blot analysis has revealed that gigantol attenuates the activity of ATP-dependent tyrosine kinase (AKT, thereby inhibiting the expression of the major EMT transcription factor, Slug, by both decreasing its transcription and increasing its degradation. The inhibitory effects of gigantol on EMT result in a decrease in the level of migration in H460 lung cancer cells. The results of this study emphasize the potential of gigantol for further development against lung cancer metastasis.

  9. Moscatilin Inhibits Lung Cancer Cell Motility and Invasion via Suppression of Endogenous Reactive Oxygen Species

    Directory of Open Access Journals (Sweden)

    Akkarawut Kowitdamrong

    2013-01-01

    Full Text Available Lung cancer is the leading cause of death among cancer patients worldwide, and most of them have died from metastasis. Migration and invasion are prerequisite processes associated with high metastasis potential in cancers. Moscatilin, a bibenzyl derivative isolated from the Thai orchid Dendrobium pulchellum, has been shown to have anticancer effect against numerous cancer cell lines. However, little is known regarding the effect of moscatilin on cancer cell migration and invasion. The present study demonstrates that nontoxic concentrations of moscatilin were able to inhibit human nonsmall cell lung cancer H23 cell migration and invasion. The inhibitory effect of moscatilin was associated with an attenuation of endogenous reactive oxygen species (ROS, in which hydroxyl radical (OH∙ was identified as a dominant species in the suppression of filopodia formation. Western blot analysis also revealed that moscatilin downregulated activated focal adhesion kinase (phosphorylated FAK, Tyr 397 and activated ATP-dependent tyrosine kinase (phosphorylated Akt, Ser 473, whereas their parental counterparts were not detectable changed. In conclusion, our results indicate the novel molecular basis of moscalitin-inhibiting lung cancer cell motility and invasion and demonstrate a promising antimetastatic potential of such an agent for lung cancer therapy.

  10. 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.

  11. Temporal and spatial regulation of anthocyanin biosynthesis provide diverse flower colour intensities and patterning in Cymbidium orchid.

    Science.gov (United States)

    Wang, Lei; Albert, Nick W; Zhang, Huaibi; Arathoon, Steve; Boase, Murray R; Ngo, Hanh; Schwinn, Kathy E; Davies, Kevin M; Lewis, David H

    2014-11-01

    This study confirmed pigment profiles in different colour groups, isolated key anthocyanin biosynthetic genes and established a basis to examine the regulation of colour patterning in flowers of Cymbidium orchid. Cymbidium orchid (Cymbidium hybrida) has a range of flower colours, often classified into four colour groups; pink, white, yellow and green. In this study, the biochemical and molecular basis for the different colour types was investigated, and genes involved in flavonoid/anthocyanin synthesis were identified and characterised. Pigment analysis across selected cultivars confirmed cyanidin 3-O-rutinoside and peonidin 3-O-rutinoside as the major anthocyanins detected; the flavonols quercetin and kaempferol rutinoside and robinoside were also present in petal tissue. β-carotene was the major carotenoid in the yellow cultivars, whilst pheophytins were the major chlorophyll pigments in the green cultivars. Anthocyanin pigments were important across all eight cultivars because anthocyanin accumulated in the flower labellum, even if not in the other petals/sepals. Genes encoding the flavonoid biosynthetic pathway enzymes chalcone synthase, flavonol synthase, flavonoid 3' hydroxylase (F3'H), dihydroflavonol 4-reductase (DFR) and anthocyanidin synthase (ANS) were isolated from petal tissue of a Cymbidium cultivar. Expression of these flavonoid genes was monitored across flower bud development in each cultivar, confirming that DFR and ANS were only expressed in tissues where anthocyanin accumulated. Phylogenetic analysis suggested a cytochrome P450 sequence as that of the Cymbidium F3'H, consistent with the accumulation of di-hydroxylated anthocyanins and flavonols in flower tissue. A separate polyketide synthase, identified as a bibenzyl synthase, was isolated from petal tissue but was not associated with pigment accumulation. Our analyses show the diversity in flower colour of Cymbidium orchid derives not from different individual pigments but from subtle

  12. Effects of iron-containing minerals on hydrothermal reactions of ketones

    Science.gov (United States)

    Yang, Ziming; Gould, Ian R.; Williams, Lynda B.; Hartnett, Hilairy E.; Shock, Everett L.

    2018-02-01

    Hydrothermal organic transformations occurring in geochemical processes are influenced by the surrounding environments including rocks and minerals. This work is focused on the effects of five common minerals on reactions of a model ketone substrate, dibenzylketone (DBK), in an experimental hydrothermal system. Ketones play a central role in many hydrothermal organic functional group transformations, such as those converting hydrocarbons to oxygenated compounds; however, how these minerals control the hydrothermal chemistry of ketones is poorly understood. Under the hydrothermal conditions of 300 °C and 70 MPa for up to 168 h, we observed that, while quartz (SiO2) and corundum (Al2O3) had no detectable effect on the hydrothermal reactions of DBK, iron-containing minerals, such as hematite (Fe2O3), magnetite (Fe3O4), and troilite (synthetic FeS), accelerated the reaction of DBK by up to an order of magnitude. We observed that fragmentation products, such as toluene and bibenzyl, dominated in the presence of hematite or magnetite, while use of troilite gave primarily the reduction products, e.g., 1, 3-diphenyl-propane and 1, 3-diphenyl-2-propanol. The roles of the three iron minerals in these transformations were further explored by (1) control experiments with various mineral surface areas, (2) measuring H2 in hydrothermal solutions, and (3) determining hydrogen balance among the organic products. These results suggest the reactions catalyzed by iron oxides (hematite and magnetite) are promoted mainly by the mineral surfaces, whereas the sulfide mineral (troilite) facilitated the reduction of ketone in the reaction solution. Therefore, this work not only provides a useful chemical approach to study and uncover complicated hydrothermal organic-mineral interactions, but also fosters a mechanistic understanding of ketone reactions in the deep carbon cycle.

  13. 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.

  14. Fundamental studies of coal liquefaction. Quarterly report No. 7, April 1--July 1, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Ross, D.S.

    1993-07-14

    In our last report we discussed observations in our cell concerning the behavior or Illinois No. 6 coal in tetralin to 460{degrees}C. We noted that there were possibly two distinct types of particles comprising the organic phase, reacting respectively at 420{degrees}--430{degrees}C, and at 450{degrees}--460{degrees}C. Alternatively we could interpret the data as describing a range of reactivity bounded by those temperatures. As evidenced by the contraction of the particles, the reactions were rapid. The particles lost half of their substance within 1 min, and we suggested that the rates were too fast to be accommodated by the commonly held scheme for coal liquefaction involving thermolytic scission of weak, bibenzyl-like bonds. Our analyses were aided by our use of Adobe Photoshop, which allows us to store, digitized versions of our recorded images. The images can then be manipulated at will to provide quantitative data on morphological changes. We noted in our last report that printer limitations prevented us from presenting images with the desirable quality, and we are at present attempting to find access to equipment which will provide satisfactory figures. Accordingly our progress will be described here without any photographs, and we expect to present a more complete account of our work in our next report. The work reported here includes studies of Illinois No. 6 coal with water as the medium, and a control run with argon as medium. Our temperature ramping was like that used last time, 25{degrees}C/min to 250{degrees}C, and then 10{degrees}C/min to 450{degrees}C. The results from the earlier work and the data presented here can therefore be directly compared.

  15. Antioxidant and cytotoxic activities of Dendrobium moniliforme extracts and the detection of related compounds by GC-MS.

    Science.gov (United States)

    Paudel, Mukti Ram; Chand, Mukesh Babu; Pant, Basant; Pant, Bijaya

    2018-04-23

    The medicinal orchid Dendrobium moniliforme contains water-soluble polysaccharides, phenanthrenes, bibenzyl derivatives, and polyphenol compounds. This study explored the antioxidant and cytotoxic activities of D. moniliforme extracts and detected their bioactive compounds. Plant material was collected from the Daman of Makawanpur district in central Nepal. Plant extracts were prepared from stems using hexane, chloroform, acetone, ethanol and methanol. The total polyphenol content (TPC) in each extract was determined using Folin-Ciocalteu's reagent and the total flavonoid content (TFC) in each extract was determined using the aluminium chloride method. The in vitro antioxidant and cytotoxic activities of each extract were determined using DPPH (2,2-diphenyl-1-picrylhydrazyl) and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assays respectively. Gas chromatography and mass spectrometry (GC-MS) analysis was used to detect bioactive compounds. TPC content was highest (116.65 μg GAE/mg of extract) in D. moniliforme chloroform extract (DMC) and TFC content was highest (116.67 μg QE/mg of extract) in D. moniliforme acetone extract (DMA). D. moniliforme hexane extract (DMH) extract showed the highest percentage of DPPH radical scavenging activity (94.48%), followed closely by D. moniliforme ethanol extract (DME) (94.45%), DMA (93.71%) and DMC (94.35%) at 800 μg/ml concentration. The antioxidant capacities of DMC, DMA, DMH and DME, which were measured in IC 50 values, were much lower 42.39 μg/ml, 49.56 μg/ml, 52.68 μg/ml, and 58.77 μg/ml respectively than the IC 50 of D. moniliforme methanol extract (DMM) (223.15 μg/ml). DMM at the concentration of 800 μg/ml most inhibited the growth of HeLa cells (78.68%) and DME at the same concentration most inhibited the growth of U251 cells (51.95%). The cytotoxic capacity (IC 50 ) of DMM against HeLa cells was 155.80 μg/ml of extract and that of DME against the U251 cells was 772.50 μg/ml of

  16. Hemilability of the 1,2-Bis(dimethylphosphino)ethane (dmpe) Ligand in Cp*Mo(NO)(κ2-dmpe).

    Science.gov (United States)

    Holmes, Aaron S; Patrick, Brian O; Levesque, Taleah M; Legzdins, Peter

    2017-09-18

    Reaction of Cp*Mo(NO)Cl 2 with 1 equiv of 1,2-bis(dimethylphosphino)ethane (dmpe) in THF at ambient temperature forms [Cp*Mo(NO)(Cl)(κ 2 -dmpe)]Cl (1), which is isolable as an analytically pure yellow powder in 65% yield. Further addition of 2 equiv of Cp 2 Co to 1 in CH 2 Cl 2 affords dark red Cp*Mo(NO)(κ 2 -dmpe) (2), which was isolated in 36% yield by recrystallization from Et 2 O at -30 °C. Reaction of a benzene solution of 2 with an equimolar amount of elemental sulfur results in the immediate production of dark blue (μ-S)[Cp*Mo(NO)(κ 1 -dmpeS)] 2 (3), which is a rare example of a bimetallic transition-metal complex bridged by only a single sulfur atom and involving Mo═S═Mo bonding. In contrast, reaction of 2 with an excess of sulfur in benzene results in the formation of Cp*Mo(NO)(η 2 -S 2 )(κ 1 -dmpeS) (4). Complex 4 can also be formed by the addition of elemental sulfur to 3, thereby indicating that 3 is a precursor to 4. Cp*Mo(NO)(κ 2 -dmpe) (2) also undergoes interesting transformations when treated with organic bromides. For instance, reaction of 2 with 5 equiv benzyl bromide in THF produces the bimetallic complex (μ-dmpe)[Cp*Mo(NO)Br 2 ] 2 (5) and bibenzyl after 4 d at 70 °C probably via radical intermediates. In contrast to its reaction with benzyl bromide, complex 2 forms [Mo(NO)Br 2 (κ 2 -dmpe)] 2 (6), olefin, alkane, and Cp*H when treated with 5 equiv of 1-bromopropane or 1-bromooctane in THF at 70 °C for 72 h. Interestingly, complex 2 does not display any reactivity with bromobenzene or 1-bromoadamantane even after being heated for several days at 70 °C. All new complexes were characterized by conventional spectroscopic and analytical methods, and the solid-state molecular structures of most of them were established by single-crystal X-ray crystallographic analyses.