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Sample records for decahydronaphthalene

  1. Modeling the Thermodynamic and Transport Properties of Decahydronaphthalene/Propane Mixtures: Phase Equilibria, Density, and Viscosity

    DTIC Science & Technology

    2011-01-01

    single constant binary interaction parameter. Density predictions from the MSLEOS were used as input mixture density values required for the FVM...viscosities were computed from a free volume model (FVM) by using a single constant binary interaction parameter. Density predictions from the MSLEOS...recording the time it takes the piston to move between the two magnetic coils . This time is converted to a value of viscosity in centipoise (cP) by an

  2. Discovery and identification of a series of alkyl decalin isomers in petroleum geological samples.

    PubMed

    Wang, Huitong; Zhang, Shuichang; Weng, Na; Zhang, Bin; Zhu, Guangyou; Liu, Lingyan

    2015-07-07

    The comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC × GC/TOFMS) has been used to characterize a crude oil and a source rock extract sample. During the process, a series of pairwise components between monocyclic alkanes and mono-aromatics have been discovered. After tentative assignments of decahydronaphthalene isomers, a series of alkyl decalin isomers have been synthesized and used for identification and validation of these petroleum compounds. From both the MS and chromatography information, these pairwise compounds were identified as 2-alkyl-decahydronaphthalenes and 1-alkyl-decahydronaphthalenes. The polarity of 1-alkyl-decahydronaphthalenes was stronger. Their long chain alkyl substituent groups may be due to bacterial transformation or different oil cracking events. This systematic profiling of alkyl-decahydronaphthalene isomers provides further understanding and recognition of these potential petroleum biomarkers.

  3. New terpenoids from Mentha pulegium L. and their antimicrobial activity.

    PubMed

    Ibrahim, Amany K

    2013-04-01

    In addition to one previously reported compound: two new terpenoidal compounds 1α, 6βdimethyl-5β-hydroxy-4β-(prop-1-en-2-yl)-decahydronaphthalen-2-one (1) and 1-(O-β-D-glucopyranosyl)-2,7-dimethyloct-5-en-3-one (2) were isolated from the chloroformic extract of Mentha pulegium L. The structure elucidation of these compounds was based primarily on 1D and 2D-nuclear magnetic resonance analyses. Compound 1 displayed moderate anti-MRSa (IC50 8.5 µg mL(-1)).

  4. Thermal Decomposition of RP-2 with Stabilizing Additives

    DTIC Science & Technology

    2010-04-01

    RP-2 are that the allowed sulfur content is much lower in RP-2 (0.1 mg/kg, compared to 30 mg/kg in RP-1), the allowed olefin concentration is lower...28,30-35 decahydronaphthalene (decalin), 33,35 and benzyl alcohol . 28,36-38 In related work, a major research effort initiated by the U.S. Air Force...additives (e.g., benzyl alcohol ). We would also like to test the effect of different reactor materials, particularly copper, on the thermal stability of

  5. Reactions of coal model compounds in tetralin using microwave energy: Effects of catalysts

    SciTech Connect

    Eray, E.; Yagmur, E.; Simsek, E.H.; Alibeyli, R.; Togrul, T.

    2006-10-01

    Reaction mechanisms of model compounds of coal in tetralin by microwave energy were investigated. Diphenylmethane (DFM), phenyl-methyl ether (anisole), and phenyl-methyl ketone (acetophenon) were chosen as model compounds. Experiments were carried out for 10 minutes of microwave energy and different catalysts were used (pyratol, zeolite, BaCl{sub 2}, AlNiMo) to find out the distribution of reaction products of the model compounds. GC and GC/MS are used to analyze the reaction products. The main reaction products from DFM and tetralin under microwave radiation with catalysts were ethyl benzene, naphthalene, 2-methyl naphthalene, 3,4-dihydronaphthaleneone, 1-1'-ethyldene 1-benzene, and 1-methyl 4-phenyl methyl benzene. The main reaction products from anisole and tetralin under microwave radiation were ethyl benzene, phenol, methyl phenol, decahydronaphthalene, and tetrahydronaphthalenol. The main reaction products from acetophenon and tetralin under microwave radiation with catalysts were ethyl benzene, methoxy benzene, decahydronaphthalene, naphthalene, tetrahydronaphthalenol, 3,4-dihydronaphthalenone and 2-butene-1-one-1,3 diphenyl. The estimated mechanism of the model compounds with tetralin is compared with the results taken from GC/MS analysis. It is obtained that the results suggested theoretically were similar with the GC/MS results.

  6. Novel approaches to the production of higher alcohols from synthesis gas. Quarterly technical progress report No. 19, April 1, 1995--June 30, 1995

    SciTech Connect

    Roberts, G.W.

    1996-10-10

    Three runs were carried out in the continuous stirred autoclave reactor with Englehard Zn-0312 T 1/8 {open_quotes}zinc chromite{close_quotes} catalyst and with decahydronaphthalene (Decalin{reg_sign}) as the slurry liquid. One short run, which was prematurely terminated by operational problems, was designed to define the effect of stirrer speed on catalyst performance. Two longer runs completed the data base required for kinetic characterization of the unpromoted {open_quotes}zinc chromite{close_quotes} catalyst. Although analysis of the data is not complete, it is evident that: (1) stirrer speed has no significant effect on the measured reaction rate, and; (2) carbon dioxide appears to inhibit catalyst activity.

  7. The Infinite Possible Growth Ambients that Support Single-Wall Carbon Nanotube Forest Growth

    NASA Astrophysics Data System (ADS)

    Kimura, Hiroe; Goto, Jundai; Yasuda, Satoshi; Sakurai, Shunsuke; Yumura, Motoo; Futaba, Don N.; Hata, Kenji

    2013-11-01

    We report the virtually infinite possible carbon feedstocks which support the highly efficient growth of single-wall carbon nanotubes (SWCNTs) using on the water-assisted chemical vapor deposition method. Our results demonstrate that diverse varieties of carbon feedstocks, in the form of hydrocarbons, spanning saturated rings (e.g. trans-deca-hydronaphthalene), saturated chains (e.g. propane), unsaturated rings (e.g. dicyclopentadiene), and unsaturated chains (e.g. ethylene) could be used as a carbon feedstocks with SWCNT forests with heights exceeding 100 ums. Further, we found that all the resultant SWCNTs possessed similar average diameter indicating that the diameter was mainly determined by the catalyst rather than the carbon feedstock within this synthetic system. A demonstration of the generality was the synthesis of a carbon nanotube forest from a highly unorthodox combination of gases where trans-decahydronaphthalene acted as the carbon feedstock and benzaldehyde acted as the growth enhancer.

  8. Effect of surfactant excess on the stability of low-polarity ferrofluids probed by small-angle neutron scattering

    SciTech Connect

    Petrenko, V. I. Avdeev, M. V.; Bulavin, L. A.; Almasy, L.; Grigoryeva, N. A.; Aksenov, V. L.

    2016-01-15

    The structures of ferrofluids (FFs) based on nonpolar solvent decahydronaphthalene, stabilized by saturated monocarboxylic acids with hydrocarbon chains of different lengths, C16 (palmitic acid) and ?12 (lauric acid), with an excess of acid molecules, have been studied by small-angle neutron scattering. It is found that the addition of acid to an initially stable system with optimal composition leads to more significant structural changes (related to aggregation) than those observed previously for this class of FFs. A comparison of the influence of monocarboxylic acids on the stability of nonpolar FFs suggests that the enhancement of aggregation is much more pronounced in the case of palmitic acid excess. This fact confirms the conclusion of previous studies, according to which an increase in the hydrocarbon chain length in a saturated acid reduces the efficiency of the corresponding FF stabilization.

  9. Effect of surfactant excess on the stability of low-polarity ferrofluids probed by small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Petrenko, V. I.; Avdeev, M. V.; Bulavin, L. A.; Almasy, L.; Grigoryeva, N. A.; Aksenov, V. L.

    2016-01-01

    The structures of ferrofluids (FFs) based on nonpolar solvent decahydronaphthalene, stabilized by saturated monocarboxylic acids with hydrocarbon chains of different lengths, C16 (palmitic acid) and ?12 (lauric acid), with an excess of acid molecules, have been studied by small-angle neutron scattering. It is found that the addition of acid to an initially stable system with optimal composition leads to more significant structural changes (related to aggregation) than those observed previously for this class of FFs. A comparison of the influence of monocarboxylic acids on the stability of nonpolar FFs suggests that the enhancement of aggregation is much more pronounced in the case of palmitic acid excess. This fact confirms the conclusion of previous studies, according to which an increase in the hydrocarbon chain length in a saturated acid reduces the efficiency of the corresponding FF stabilization.

  10. Novel approaches to the production of higher alcohols from synthesis gas. Quarterly technical progress report No. 17, October 1, 1994-- December 31, 1994

    SciTech Connect

    1996-07-05

    A series of experiments in which the stirrer speed was varied during a methanol synthesis run with BASF S3-86 catalyst showed that mass transfer limitations were present at 750 psig reactor pressure and at space velocities of 5000 and 10000 sl/kg(cat.)-hr.. There was no effect of stirrer speed on reaction rate at 2500 psig reactor pressure and 16500 sl/kg(cat.)-hr. space velocity. However, this was probably due to a close approach to equilibrium rather than to the lack of a mass transfer effect. The most plausible explanation for the presence of a mass transfer influence is the position of the gas feed dip tube relative to the agitator impeller. A second set of stirrer speed experiments using the same catalyst showed that feeding into the reactor headspace produced much lower reaction rates, compared with gas feed through a dip tube. The headspace feed also showed a strong dependence on stirrer speed, consistent with the dip tube feed results. In a ``blank` run at 375{degree}C with decahydronaphthalene, about 110 mL of the initial charge of 150 mL remained in the reactor after 73 hours of operation at 375{degree}C and 850 psig of hydrogen. The rate of hydrocarbon evolution was low throughout the run. Decalin is the most stable liquid identified to date. Three stirred autoclave runs with a commercial, high-pressure methanol synthesis catalyst (zinc chromite) slurried in decahydronaphthalene ended son after the initial catalyst reduction due to failures of the liquid return pump in the overhead system. However, the catalyst appeared to be reduced and the liquid appeared to be stable. 4 figs., 1 tab.

  11. The origin of light cycloalkanes in petroleum

    SciTech Connect

    Mango, F.D. )

    1990-01-01

    It has been suggested that the light cycloalkanes in petroleum are generated through the thermal decomposition of heavier polycyclic natural products, such as the steranes and triterpanes. However, no support could be found for the assumption that the polycycloalkanes should decompose to light cycloalkanes at typical subsurface temperatures. For example, at 150{degree}C, decahydronaphthalene-the bicyclodecyl unit fundamental to the steranes and triterpanes-has a half-life of approximately 30 billion years. At this same temperature, cyclohexane has a half-life of approximately 60 billion years. The surprising thermal stability of the cycloalkane ring can be traced to a prohibitively high activation energy for ring opening due to the steric strain associated with the {beta}-elimination step. Cholestane undergoes thermal decomposition almost exclusively by loss of the alkyl side chain. Under thermal conditions sufficiently severe to break the carbon-carbon bonds of normal alkanes (weeks, 330{degree}C), cholestane gives only insignificant amounts of light cycloalkanes. It is most doubtful, therefore, that the C{sub 5} to C{sub 9} cycloalkanes could be thermally produced from natural products like the steranes and triterpanes. An alternative hypothesis is offered in which the light cycloalkanes in petroleum are formed in a steady-state catalytic process.

  12. Structure and mechanical properties of isotactic polypropylene (iPP) gels formed at different cooling temperatures

    NASA Astrophysics Data System (ADS)

    Okoshi, Ryusuke; Hotta, Atsushi

    2015-03-01

    The effects of the cooling temperature on the crystalline network formation and the mechanical properties of isotactic polypropylene (iPP) gels were evaluated. iPP/decahydronaphthalene gels were prepared at different cooling temperatures varying from 25 degrees C to -196 degrees C. Tensile test was carried out to measure the mechanical properties of the gels. Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) analyses were conducted to observe the density and the homogeneity of the network structures. It was found that the iPP gel quenched at -196 degrees C was highly elastic, exhibiting the highest fracture strain and stress of 2500% and 230 kPa. The SEM analysis revealed that nano-crystals were formed, which acted as crosslinkers that were distributed throughout the gels by quenching below -40 degrees C. By contrast, spherulites were observed to have grown inhomogeneously by cooling above -20 degrees C. It was found by DSC that the amount of crystals was increased by decreasing the cooling temperatures, indicating an increase in the density of the network structures. From these results, it was therefore concluded that iPP gel quenched at -196 degrees C possessed the highest mechanical property due to its dense and homogeneous network structures.

  13. Determination of unconverted HDPE in coal/plastics co-liquefaction stream samples

    SciTech Connect

    Robbins, G.A.; Winschel, R.A.; Burke, F.P.

    1996-12-31

    In several coal/plastics liquefaction runs performed by Hydrocarbon Technologies, Inc. (HTI), a substantial amount of incompletely converted high-density polyethylene (HDPE) was present in ash-free recycle resid streams when either the ROSE-SR unit was used in Run POC-2, or the pressure filter unit was used in Runs CMSL-8 and CMSL-9. This indicates that the HDPE is less reactive than coal at the liquefaction conditions used. In these ash-free streams, there is no solid organic or inorganic material arising from the coal, and the incompletely converted HDPE can be recovered by extraction and filtration with tetrahydrofuran (THF) at room temperature. The HDPE (or HDPE-like material, which could also consist of heavy waxes) is THF insoluble. However, in ashy streams, there are both inorganic ({open_quotes}ash{close_quotes}) and organic (unconverted coal) components present from liquefaction of the coal, that interfere with an easy and clean separation of the HDPE from the coal/plastics liquefaction stream sample. Therefore, CONSOL developed an analytical procedure for HDPE in the ashy stream samples based on extraction of HDPE from the sample using hot (150{degrees}C) decalin (decahydronaphthalene), in which the HDPE is soluble. The decalin extraction is both preceded and succeeded by extractions and washes with THF at room temperature, to remove the coal-derived components from the sample.

  14. Far infrared (terahertz) spectroscopy of a series of polycyclic aromatic hydrocarbons and application to structure interpretation of asphaltenes and related compounds

    NASA Astrophysics Data System (ADS)

    Cataldo, Franco; Angelini, Giancarlo; García-Hernández, D. A.; Manchado, Arturo

    2013-07-01

    A series of 33 different polycyclic aromatic hydrocarbons (PAHs) were studied by far infrared spectroscopy (terahertz spectroscopy) in the spectral range comprised between 600 and 50 cm-1. In addition to common PAHs like naphthalene, anthracene, phenanthrene, fluoranthene, picene, pyrene, benzo[α]pyrene, and perylene, also quite unusual PAHs were studied like tetracene, pentacene, acenaphtene, acenaphtylene, triphenylene, and decacyclene. A series of alkylated naphthalenes and anthracenes were studied as well as methypyrene. Partially or totally hydrogenated PAHs were also object of the present investigation, ranging from tetrahydronaphthalene (tetralin) to decahydronaphthalene (decalin), 9,10-dihydroanthracene, 9,10-dihydrophenanthrene, hexahydropyrene, and dodecahydrotriphenylene. Finally, the large and quite rare PAHs coronene, quaterrylene, hexabenzocoronene, and dicoronylene were studied by far infrared spectroscopy. The resulting reference spectra were used in the interpretation of the chemical structure of asphaltenes (as extracted from a heavy petroleum fraction and from bitumen), the chemical structures of other petroleum fractions known as DAE (distillate aromatic extract) and RAE (residual aromatic extract), and a possible interpretation of components of the chemical structure of anthracite coal. Asphaltenes, heavy petroleum fractions, and coal were proposed as model compounds for the interpretation of the emission spectra of certain proto-planetary nebulae (PPNe) with a good matching in the mid infrared between the band pattern of the PPNe emission spectra and the spectra of these oil fractions or coal. Although this study was finalized in an astrochemical context, it may find application also in the petroleum and coal chemistry.

  15. PROMOTED ZINC CHROMITE CATALYSTS FOR HIGHER ALCOHOL SYNTHESIS

    SciTech Connect

    Ms. Xiaolei Sun; Professor George W. Roberts

    2000-08-29

    During this reporting period, a ''zinc chromite'' catalyst promoted with 6 wt.% cesium (Cs) was evaluated at the following conditions: Temperature--375 C; Total Pressure--6.8 MPa (1000 psig); Gas Hourly Space Velocity (GHSV) - 5000 standard liters/kg(cat)-hr, and; H{sub 2}/CO feed ratio--1.0 mole/mole. Decahydronaphthalene (DHN) was used as the slurry liquid. The experiment lasted for eight days of continuous operation. Although the experimental data once again did not exhibit the desired degree of consistency, the data did show that methanol was the primary reaction product. The slurry liquid did not decompose or alkylate to a measurable extent during the continuous 8-day experiment. There was a relatively significant loss of catalyst surface area during the experiment. Gas chromatography/mass spectrometry (GC/MS) analysis of various fractions of ''spent'' THQ was carried out. The fractions were prepared by silica gel liquid chromatography (LC). Chemical formuli and probable structures for each major compound were obtained. However, a higher degree of purification will be necessary to allow nuclear magnetic resonance (NMR) analysis to be used for definitive compound identification. A new Maxpro gas booster (DLE 15-75) was purchased because the existing Haskel gas booster once again developed a severe leak of carbon monoxide and hydrogen, and was judged to be unworthy of repair.

  16. Carbonaceous sorbents for high-temperature interactive liquid chromatography of polyolefins.

    PubMed

    Chitta, Rajesh; Macko, Tibor; Brüll, Robert; Miller, Matthew; Cong, Rongjuan; deGroot, Willem

    2013-07-01

    The elution behavior of polyethylene (PE) and the three stereoisomers of polypropylene (PP) was studied on porous graphite along with three other carbon-based sorbents, carbon-clad zirconia particles, activated carbon, and exfoliated graphite in a systematic way in this work. Decahydronaphthalene, 1,2,3,4-tetrahydronaphthalene, 1,3,5-trimethylbenzene, tetrachloroethylene, xylene and p-xylene were used as mobile phases. While PE is adsorbed to various extents on all the tested carbonaceous sorbents from the majority of the solvents, PP is fully adsorbed only in selected cases. Testing alcohols (C7-C9) as mobile phase with Hypercarb™ indicates that all stereoisomers of PP are selectively adsorbed and desorbed when a solvent gradient alcohol→1,2,4-trichlorobenzene is used at 160°C. The retention of all stereoisomers of PP increases with the polarity of the alcohol. Linear PE is retained on Hypercarb™ even from 1,2-dichloro- and 1,2,4-trichlorobenzene, when a temperature below 120°C is applied, while it is not retained from these solvents at higher temperatures. All stereoisomeric forms of PP are not adsorbed under the same conditions. Some of the tested new sorbent/solvent systems have potential to be applied in routine analysis of industrially synthesised polyolefins.

  17. High-temperature slurry reactors for synthesis gas reactions. 1: Liquid thermal stability

    SciTech Connect

    Roberts, G.W.; Marquez, M.A.; McCutchen, M.S.; Haney, C.A.; Shin, I.D.

    1997-10-01

    The use of slurry reactors has been limited to reactions that take place at temperatures below about 573 K because many of the liquids that have been used to suspend the solid catalyst are not stable above this temperature. The thermal stability of a number of organic liquids was evaluated at temperatures between 648 and 698 K and at H{sub 2} partial pressures of about 7 MPa. Certain saturated and partially-saturated, fused-ring compounds with no alkyl groups or bridges are quite stable at these conditions. Of the compounds tested, tetrahydronaphthalene, tetrahydroquinoline, and decahydronaphthalene were the most stable. Analysis of the liquids at the end of the thermal stability evaluation supports some speculation concerning possible degradation reactions. The motivation for this research was the desire to synthesize higher (C{sub 2}{minus}C{sub 6}) alcohols in a slurry reactor from a mixture of carbon monoxide (CO) and hydrogen (H{sub 2}), so-called synthesis gas. Alcohols such as isobutanol and isoamyl alcohol could be a source of the branched olefins that are needed to produce octane enhancers such as methyl tert-butyl ether (MTBE) and tert-amyl methyl ether (TAME).

  18. Novel approaches to the production of higher alcohols from synthesis gas. Quarterly technical progress report No. 18, January 1, 1995-- March 31, 1995

    SciTech Connect

    1996-07-05

    A set of stirrer speed experiments using the Cu/ZnO methanol synthesis catalyst showed that introducing the gas feed into the reactor through an extended dip tube eliminated the dependency of catalyst performance on stirrer speed. The methanol productivity data from the reactor gas feed configuration tests conducted in December, 1994 and January, 1995, were correlated with stirrer speed. The influence on mass transfer on catalyst performance was clearly illustrated for each gas feed location. The ``high pressure, high temperature` zinc chromite methanol synthesis catalyst showed surprising activity at temperatures as low as 300{degree}C during the first successful stirred autoclave run with this catalyst. No C{sub 2{sup {plus}}} alcohols were detected, but significant levels of C{sub 2}-C{sub 4} olefins and dimethyl ether (DME) were produced. The presence of olefins suggests that higher alcohols might have formed and subsequently dehydrated. The slurry liquid, decahydronaphthalene, showed no evidence of decomposition during 15 days of continuous operation. 2 figs., 1 tab.

  19. Far infrared (terahertz) spectroscopy of a series of polycyclic aromatic hydrocarbons and application to structure interpretation of asphaltenes and related compounds.

    PubMed

    Cataldo, Franco; Angelini, Giancarlo; García-Hernández, D Aníbal; Manchado, Arturo

    2013-07-01

    A series of 33 different polycyclic aromatic hydrocarbons (PAHs) were studied by far infrared spectroscopy (terahertz spectroscopy) in the spectral range comprised between 600 and 50 cm(-1). In addition to common PAHs like naphthalene, anthracene, phenanthrene, fluoranthene, picene, pyrene, benzo[α]pyrene, and perylene, also quite unusual PAHs were studied like tetracene, pentacene, acenaphtene, acenaphtylene, triphenylene, and decacyclene. A series of alkylated naphthalenes and anthracenes were studied as well as methypyrene. Partially or totally hydrogenated PAHs were also object of the present investigation, ranging from tetrahydronaphthalene (tetralin) to decahydronaphthalene (decalin), 9,10-dihydroanthracene, 9,10-dihydrophenanthrene, hexahydropyrene, and dodecahydrotriphenylene. Finally, the large and quite rare PAHs coronene, quaterrylene, hexabenzocoronene, and dicoronylene were studied by far infrared spectroscopy. The resulting reference spectra were used in the interpretation of the chemical structure of asphaltenes (as extracted from a heavy petroleum fraction and from bitumen), the chemical structures of other petroleum fractions known as DAE (distillate aromatic extract) and RAE (residual aromatic extract), and a possible interpretation of components of the chemical structure of anthracite coal. Asphaltenes, heavy petroleum fractions, and coal were proposed as model compounds for the interpretation of the emission spectra of certain proto-planetary nebulae (PPNe) with a good matching in the mid infrared between the band pattern of the PPNe emission spectra and the spectra of these oil fractions or coal. Although this study was finalized in an astrochemical context, it may find application also in the petroleum and coal chemistry. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Elucidation of the molecular mechanism and the efficacy in vivo of a novel 1,4-benzoquinone that inhibits 5-lipoxygenase.

    PubMed

    Schaible, A M; Filosa, R; Temml, V; Krauth, V; Matteis, M; Peduto, A; Bruno, F; Luderer, S; Roviezzo, F; Di Mola, A; de Rosa, M; D'Agostino, B; Weinigel, C; Barz, D; Koeberle, A; Pergola, C; Schuster, D; Werz, O

    2014-05-01

    1,4-Benzoquinones are well-known inhibitors of 5-lipoxygenase (5-LOX, the key enzyme in leukotriene biosynthesis), but the molecular mechanisms of 5-LOX inhibition are not completely understood. Here we investigated the molecular mode of action and the pharmacological profile of the novel 1,4-benzoquinone derivative 3-((decahydronaphthalen-6-yl)methyl)-2,5-dihydroxycyclohexa-2,5-diene-1,4-dione (RF-Id) in vitro and its effectiveness in vivo. Mechanistic investigations in cell-free assays using 5-LOX and other enzymes associated with eicosanoid biosynthesis were conducted, along with cell-based studies in human leukocytes and whole blood. Molecular docking of RF-Id into the 5-LOX structure was performed to illustrate molecular interference with 5-LOX. The effectiveness of RF-Id in vivo was also evaluated in two murine models of inflammation. RF-Id consistently suppressed 5-LOX product synthesis in human leukocytes and human whole blood. RF-Id also blocked COX-2 activity but did not significantly inhibit COX-1, microsomal PGE2 synthase-1, cytosolic PLA2 or 12- and 15-LOX. Although RF-Id lacked radical scavenging activity, reducing conditions facilitated its inhibitory effect on 5-LOX whereas cell stress impaired its efficacy. The reduced hydroquinone form of RF-Id (RED-RF-Id) was a more potent inhibitor of 5-LOX as it had more bidirectional hydrogen bonds within the 5-LOX substrate binding site. Finally, RF-Id had marked anti-inflammatory effects in mice in vivo. RF-Id represents a novel anti-inflammatory 1,4-benzoquinone that potently suppresses LT biosynthesis by direct inhibition of 5-LOX with effectiveness in vivo. Mechanistically, RF-Id inhibits 5-LOX in a non-redox manner by forming discrete molecular interactions within the active site of 5-LOX. © 2014 The British Pharmacological Society.

  1. Elucidation of the molecular mechanism and the efficacy in vivo of a novel 1,4-benzoquinone that inhibits 5-lipoxygenase

    PubMed Central

    Schaible, A M; Filosa, R; Temml, V; Krauth, V; Matteis, M; Peduto, A; Bruno, F; Luderer, S; Roviezzo, F; Di Mola, A; Rosa, M; D'Agostino, B; Weinigel, C; Barz, D; Koeberle, A; Pergola, C; Schuster, D; Werz, O

    2014-01-01

    Background and Purpose 1,4-Benzoquinones are well-known inhibitors of 5-lipoxygenase (5-LOX, the key enzyme in leukotriene biosynthesis), but the molecular mechanisms of 5-LOX inhibition are not completely understood. Here we investigated the molecular mode of action and the pharmacological profile of the novel 1,4-benzoquinone derivative 3-((decahydronaphthalen-6-yl)methyl)-2,5-dihydroxycyclohexa-2,5-diene-1,4-dione (RF-Id) in vitro and its effectiveness in vivo. Experimental Approach Mechanistic investigations in cell-free assays using 5-LOX and other enzymes associated with eicosanoid biosynthesis were conducted, along with cell-based studies in human leukocytes and whole blood. Molecular docking of RF-Id into the 5-LOX structure was performed to illustrate molecular interference with 5-LOX. The effectiveness of RF-Id in vivo was also evaluated in two murine models of inflammation. Key Results RF-Id consistently suppressed 5-LOX product synthesis in human leukocytes and human whole blood. RF-Id also blocked COX-2 activity but did not significantly inhibit COX-1, microsomal PGE2 synthase-1, cytosolic PLA2 or 12- and 15-LOX. Although RF-Id lacked radical scavenging activity, reducing conditions facilitated its inhibitory effect on 5-LOX whereas cell stress impaired its efficacy. The reduced hydroquinone form of RF-Id (RED-RF-Id) was a more potent inhibitor of 5-LOX as it had more bidirectional hydrogen bonds within the 5-LOX substrate binding site. Finally, RF-Id had marked anti-inflammatory effects in mice in vivo. Conclusions and Implications RF-Id represents a novel anti-inflammatory 1,4-benzoquinone that potently suppresses LT biosynthesis by direct inhibition of 5-LOX with effectiveness in vivo. Mechanistically, RF-Id inhibits 5-LOX in a non-redox manner by forming discrete molecular interactions within the active site of 5-LOX. PMID:24467325

  2. Comparative chemical profiling, cholinesterase inhibitions and anti-radicals properties of essential oils from Polygonum hydropiper L: a preliminary anti- Alzheimer's study.

    PubMed

    Ayaz, Muhammad; Junaid, Muhammad; Ullah, Farhat; Sadiq, Abdul; Khan, Mir Azam; Ahmad, Waqar; Shah, Muhammad Raza; Imran, Muhammad; Ahmad, Sajjad

    2015-11-04

    Cholinesterase inhibition is a vital target for the development of novel and mechanism based inhibitors, owing to their role in the breakdown of acetylcholine (ACh) neurotransmitter to treat various neurological disorders including Alzheimer's disease (AD). Similarly, free radicals are implicated in the progression of various diseases like neurodegenerative disorders. Due to lipid solubility and potential to easily cross blood brain barrier, this study was designed to investigate the anticholinesterase and antioxidant potentials of the standardized essential oils from the leaves and flowers of Polygonum hydropiper. Essential oils from the leaves (Ph.LO) and flowers (Ph.FO) of P. hdropiper were isolated using Clevenger apparatus. Oil samples were analyzed by GC-MS to identify major components and to attribute the antioxidant and anticholinesterase activity to specific components. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory potentials of the samples were determined following Ellman's assay. Antioxidant assays were performed using 1,1-diphenyl,2-picrylhydrazyl (DPPH), 2,2-azinobis[3-ethylbenzthiazoline]-6-sulfonic acid (ABTS) and hydrogen peroxide (H2O2) free radical scavenging assays. In the GC-MS analysis 141 and 122 compounds were indentified in Ph.LO and Ph.FO respectively. Caryophylene oxide (41.42 %) was the major component in Ph.FO while decahydronaphthalene (38.29 %) was prominent in Ph.LO. In AChE inhibition, Ph.LO and Ph.FO exhibited 87.00** and 79.66***% inhibitions at 1000 μg/ml with IC50 of 120 and 220 μg/ml respectively. The IC50 value for galanthamine was 15 μg/ml. In BChE inhibitory assay, Ph.LO and Ph.FO caused 82.66*** (IC50 130 μg/ml) and 77.50***% (IC50 225 μg/ml) inhibitions respectively at 1000 μg/ml concentration. In DPPH free radical scavenging assay, Ph.LO and Ph.FO exhibited IC50 of 20 and 200 μg/ml respectively. The calculated IC50s were 180 & 60 μg/ml for Ph.LO, and 45 & 50 μg/ml for Ph.FO in scavenging

  3. The 1,4 benzoquinone-featured 5-lipoxygenase inhibitor RF-Id induces apoptotic death through downregulation of IAPs in human glioblastoma cells.

    PubMed

    Zappavigna, S; Scuotto, M; Cossu, A M; Ingrosso, D; De Rosa, M; Schiraldi, C; Filosa, R; Caraglia, M

    2016-10-22

    Embelin is a potent dual inhibitor of 5-lipoxigenase (5-LOX) and microsomal prostaglandin E2 synthase (mPGES)-1 that suppresses proliferation of human glioma cells and induces apoptosis by inhibiting XIAP and NF-κB signaling pathway. Synthetic structural modification yielded the derivative 3-((decahydronaphthalen-6-yl)methyl)-2,5-dihydroxycyclohexa-2,5-diene-1,4-dione (RF-Id), an embelin constrained analogue, with improved efficiency against 5-LOX in human neutrophils and anti-inflammatory activity in vivo. Taking into account that lipoxygenase (LOX) metabolites, from arachidonic acid and linoleic acid, have been implicated in tumor progression, here, we determined whether RF-Id was able to hinder glioblastoma (GBM) cancer cell growth and the related mechanisms. U87MG and LN229 cells were plated in 96-wells and treated with increasing concentrations of RF-Id. Cell viability was evaluated by MTT assay. The effects of the compounds on cell cycle, apoptosis, oxidative stress and autophagy were assessed by flow cytometry (FACS). The mode of action was confirmed by Taqman apoptosis array and evaluating caspase cascade and NFκB pathway by western blotting technique. Here, we found that RF-Id induced a stronger inhibition of GBM cell growth than treatment with embelin. Flow cytometry analysis showed that RF-Id induced about 30 % apoptosis and a slight increase of autophagy after 72 h on U87-MG cells. Moreover, the compound induced an increase in the percentage of cells in G2 and S phase that was paralleled by an increase of p21 and p27 expression but no significant changes of the mitochondrial membrane potential; array analysis showed a significant upregulation of CASP8 and a downregulation of IAP family and NFκB genes in cells treated with RF-Id. RF-Id induced a significant cleavage of caspases 8, 9, 3 and 7, blocked c-IAP2/XIAP interaction by inducing XIAP degradation and inhibited NFκB pathway. RF-Id induced a caspase-dependent apoptosis in GBM cells by