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Sample records for dimer trans-resveratrol-3-o-glucuronide glucosides

  1. Jasamplexosides A, B and C: Novel Dimeric and Trimeric Secoiridoid Glucosides from Jasminum amplexicaule.

    PubMed

    Tanahashi, T; Shimada, A; Nagakura, N; Nayeshiro, H

    1992-12-01

    Three new secoiridoid glucosides, jasamplexosides A, B and C, were isolated from the crude drug "Niu du teng", the leaves and stems of JASMINUM AMPLEXICAULE, together with the known secoiridoid glucosides, 10-hydroxyligstroside and jasminoside. Their structural elucidation by spectroscopic studies is described.

  2. Formation of bilirubin glucoside

    PubMed Central

    Wong, Kim Ping

    1971-01-01

    1. Rat liver microsomal preparation can effect the transglucosylation from UDP-glucose to bilirubin in the presence of Mg2+. 2. Other nucleotides, namely CDP-glucose, ADP-glucose and GDP-glucose, were not active as glucosyl donors. 3. Only trace amounts of galactose, galacturonic acid and N-acetylglucosamine were conjugated to bilirubin when their respective UDP derivatives were used in the reaction mixture. 4. The azobilirubin glucosides produced by coupling with p-diazobenzenesulphonic acid and diazotized ethyl anthranilic acid were separable from the corresponding azobilirubin glucuronides by t.l.c. 5. The glucoside was, however, hydrolysed by both β-glucosidase and various preparations of β-glucuronidase; azobilirubin and glucose were liberated in the process. 6. Kinetic studies showed that the effects of pH and Mg2+ on the two conjugating systems were similar. 7. The specific activities of hepatic bilirubin UDP-glucosyltransferase, expressed as μg of bilirubin `equivalents' conjugated/h per mg of protein, are respectively 1.7 and 2.4 for male and female rats. 8. The Km values for bilirubin and UDP-glucose are 5.7×10−5m and 1.6×10−3m respectively. 9. The glucoside and glucuronide conjugations of bilirubin are discussed in relation to the availability of the conjugating agents and aglycone in the liver. ImagesFig. 1. PMID:5144254

  3. ESIMS and NMR studies on the selective deprotection of acetylated glucosides by dibutyltin oxide.

    PubMed

    Wang, Shao-Min; Zhu, Wei-Guo; Kang, Jian-Xun; Liu, Hong-Min; Chen, Jun-Miao; Li, Cui-Ping; Zhang, Kai

    2011-02-01

    The reaction process for the selective deprotection of acetylated glucosides by dibutyltin oxide in methanol is investigated by using methyl 2,3,4,6-tetra-O-acetyl-α-d-glucopyranoside as a model substrate with ESIMS and NMR techniques. According to the results, it is inferred that at first, dimeric 1,3-dimethoxytetrabutyldistannoxane is formed by the reaction of dibutyltin oxide with methanol, and then the tetraorganodistannoxane reacts with the acetylated glucoside to produce glucoside-organotin complex intermediates. Finally, the complex intermediates are hydrolyzed leading to the free-OH glucoside and organotin acetate derivatives. The reaction is affected by neighboring group participation and steric hindrance, which allow for high selectivities among different acetyl groups in acetylated glucosides.

  4. Diversification of an ancient theme: hydroxynitrile glucosides.

    PubMed

    Bjarnholt, Nanna; Rook, Fred; Motawia, Mohammed Saddik; Cornett, Claus; Jørgensen, Charlotte; Olsen, Carl Erik; Jaroszewski, Jerzy W; Bak, Søren; Møller, Birger Lindberg

    2008-05-01

    Many plants produce cyanogenic glucosides as part of their chemical defense. They are alpha-hydroxynitrile glucosides, which release toxic hydrogen cyanide (HCN) upon cleavage by endogenous plant beta-glucosidases. In addition to cyanogenic glucosides, several plant species produce beta- and gamma-hydroxynitrile glucosides. These do not release HCN upon hydrolysis by beta-glucosidases and little is known about their biosynthesis and biological significance. We have isolated three beta-hydroxynitrile glucosides, namely (2Z)-2-(beta-D-glucopyranosyloxy)but-2-enenitrile and (2R,3R)- and (2R,3S)-2-methyl-3-(beta-D-glucopyranosyloxy)butanenitrile, from leaves of Ribesuva-crispa. These compounds have not been identified previously. We show that in several species of the genera Ribes, Rhodiola and Lotus, these beta-hydroxynitrile glucosides co-occur with the L-isoleucine-derived hydroxynitrile glucosides, lotaustralin (alpha-hydroxynitrile glucoside), rhodiocyanosides A (gamma-hydroxynitrile glucoside) and D (beta-hydroxynitrile glucoside) and in some cases with sarmentosin (a hydroxylated rhodiocyanoside A). Radiolabelling experiments demonstrated that the hydroxynitrile glucosides in R. uva-crispa and Hordeum vulgare are derived from L-isoleucine and L-leucine, respectively. Metabolite profiling of the natural variation in the content of cyanogenic glucosides and beta- and gamma-hydroxynitrile glucosides in wild accessions of Lotus japonicus in combination with genetic crosses and analyses of the metabolite profile of the F2 population provided evidence that a single recessive genetic trait is most likely responsible for the presence or absence of beta- and gamma-hydroxynitrile glucosides in L. japonicus. Our findings strongly support the notion that the beta- and gamma-hydroxynitrile glucosides are produced by diversification of the cyanogenic glucoside biosynthetic pathway at the level of the nitrile intermediate.

  5. Acidic conjugate of phenols in insects; glucoside phosphate and glucoside sulphate derivatives.

    PubMed

    Ngah, W Z; Smith, J N

    1983-06-01

    Conjugates of p-nitrophenol in nine species of insects were identified by paper chromatography and ionophoresis as the glucoside, the sulphate, the phosphate and the glucoside phosphate. Metabolites with similar properties to the glucoside phosphates were also formed from 8-hydroxyquinoline, 1-naphthol and 4-methylumbelliferone in Tenebrio larvae. Tenebrio larvae also metabolized p-nitrophenol to a compound believed to be p-nitrophenyl glucoside-6-sulphate. None of the nine species of insect used was able to metabolize [14C]benzoic acid to a glucoside-phosphate or glucoside-sulphate conjugate.

  6. Glucosides from the roots of Capparis tenera.

    PubMed

    Su, Dong-Min; Wang, Ying-Hong; Yu, Shi-Shan; Yu, De-Quan; Hu, You-Cai; Tang, Wen-Zhao; Liu, Geng-Tao; Wang, Wen-Jie

    2007-12-01

    Two new lignan glucosides, compounds 2 and 3, two new 1H-indole-alkaloid glucosides, 5 and 6, as well as two new phenolic glucosides, 7 and 10, were isolated from the roots of Capparis tenera, together with five known compounds. Their structures were characterized by chemical and spectroscopic methods. Most of these isolates were obtained for the first time from Capparidaceae. The antioxidant and anti-inflammatory activities of the new compounds were investigated.

  7. Immunochemical approach for zearalenone-4-glucoside determination.

    PubMed

    Beloglazova, N V; De Boevre, M; Goryacheva, I Yu; Werbrouck, S; Guo, Y; De Saeger, S

    2013-03-15

    Zearalenone-4-β-D-glucopyranoside (zearalenone-4-glucoside) detection techniques, based on a combination of acidic or enzymatic hydrolysis of the masked mycotoxin to the parent form (i.e. zearalenone), and immunochemical determination of zearalenone-4-glucoside as a difference between the zearalenone concentration after and before cleavage of the glycosidic bond were developed. The limit of detection for zearalenone-4-glucoside, achieved for the enzyme linked immunosorbent assay, was 3 μg kg(-1); the cut-off level for the sum of zearalenone and zearalenone-4-glucoside determination by a qualitative gel-based immunoassay was 50 μg kg(-1). Trifluoromethanesulfonic acid was checked for acidic hydrolysis and resulted in approximately 70% of glycosidic bond cleavage in optimal conditions. Seven different glycoside hydrolases were tested during the design of the enzymatic hydrolysis technique. Enzymatic hydrolysis combined with enzyme linked immunosorbent assay and gel-based immunoassay determinations was applied for the determination of zearalenone-4-glucoside or the sum of zearalenone and zearalenone-4-glucoside in cereal samples. The chosen enzyme (glucosidase from Aspergillus niger) allowed to cleave 102% of zearalenone-4-glucoside in standard solutions and 85% in cereal samples. Liquid chromatography coupled to tandem mass spectrometry was used as confirmatory method. As a result, good correlations between immunochemical techniques and the chromatographic data were obtained. The developed technique is suitable for simultaneous immunochemical determination of zearalenone and its masked form, zearalenone-4-glucoside. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. A new isoflavone glucoside from Pterocarpus santalinus.

    PubMed

    Krishnaveni, K S; Srinivasa Rao, J V

    2000-01-01

    A new isoflavone glucoside (1) together with the known santal has been isolated from the heartwood of Pterocarpus santalinus. Based on spectral methods, the structure of the new compound was elucidated as 4',5-dihydroxy 7-O-methyl isoflavone 3'-O-beta-D-glucoside.

  9. Physico-chemical and chromatic characterization of malvidin 3-glucoside-vinylcatechol and malvidin 3-glucoside-vinylguaiacol wine pigments.

    PubMed

    Quijada-Morín, Natalia; Dangles, Olivier; Rivas-Gonzalo, Julián C; Escribano-Bailón, M Teresa

    2010-09-08

    The physicochemical and chromatic features of malvidin 3-glucoside-vinylcatechol (PA1) and malvidin 3-glucoside-vinylguaiacol (PA2) adducts were investigated. Important differences between both pigments were observed. In the investigated pH range (2.0-4.5), our results suggest that PA1 could be considered as a noncovalent dimer of two pyranoflavylium ions (AH)2 which undergo a hydration reaction in two successive steps, with no proton transfer. In contrast, only proton transfer equilibrium between the pyranoflavylium ion and the quinonoid bases was observed for PA2. The hydration and acidity thermodynamic constants of both pyranoanathocyanins were determined by UV-vis spectroscopy. Pigment PA1 was shown to be less sensitive to bisulfite addition than to water addition, and PA2 seems to be largely insensitive to both water and bisulfite additions. The binding constants for the interaction between the pigments and (+)-catechin in aqueous solution and the changes in the CIELAB parameters that it provoked were also determined. The huge increase in the absorption of the pyranoflavylium ion of PA2 when it binds catechin has no equivalent for anthocyanins and nicely outlines the potential of pyranoanthocyanins in the expression of natural colors.

  10. Secoiridoid Glucosides Isolated from Gentiana gelida.

    PubMed

    Caliş, I; Rüegger, H; Chun, Z; Sticher, O

    1990-08-01

    From the aerial parts of GENTIANA GELIDA two new strongly bitter acylsecoiridoid glucosides, gelidoside ( 1) and gentomoside ( 2), have been isolated along with five known secoiridoid glucosides, trifloroside ( 3), gentiopicroside ( 4), swertiamarin ( 5), eustomoside ( 6), and eustomorusside ( 7). The structures of the compounds were elucidated by a combination of spectroscopic methods (UV, IR, (1)H-NMR, 2D-NMR, EI- and FAB-MS).

  11. [Flavanonol glucosides of Smilax glabra Roxb].

    PubMed

    Chen, G; Shen, L; Jiang, P

    1996-06-01

    Three flavanonol glucosides have been isolated from the rhizome of Smilax glabra. Their structures were identified as isoengetitin, isoastilbin and astilbin on the basis of their physicochemical and spectral data. Full as signment of their 1HNMR and 13CNMR chemical shift signals was established by various 2D-NMR techniques. Their glucosidic bond structures were determined for the first time. Isoastilbin was isolated from Smilax for the first time.

  12. Oligomeric secoiridoid glucosides from Jasminum abyssinicum.

    PubMed

    Gallo, Francesca Romana; Palazzino, Giovanna; Federici, Elena; Iurilli, Raffaella; Monache, Franco Delle; Chifundera, Kusamba; Galeffi, Corrado

    2006-03-01

    From the root bark of Jasminum abyssinicum (Oleaceae) collected in Congo was isolated tree oligomeric secoiridoid glucosides named craigosides A-C. The three compounds are esters of a cyclopentanoid monoterpene with an iridane skeleton, esterified with three, two and two, respectively, units of oleoside 11-methyl ester. The structures were elucidated by spectroscopic methods and chemical correlations.

  13. Cytogenetic activity of the coumarin glucoside seseloside

    SciTech Connect

    Arshava, E.A.

    1986-05-01

    The cytogenetic effect of the coumarin glucoside seseloside on plant objects was studied. It was established that low concentrations of the preparation (from 1 x 10/sup -5/ to 1 x 10/sup -3/ ..mu..g/ml) inhibit both spontaneous and radiation-induced mutagenesis. The effect of high concentrations (10 and 100 ..mu..g/ml) causes a mutagenic effect.

  14. Two new terpenoid glucosides from Aster flaccidus.

    PubMed

    Gan, L-S; Zhan, Z-J; Yang, S-P; Yue, J-M

    2006-01-01

    Two new terpenoid glucosides, namely 2-O-beta-D-glucopyranoside-vicodiol (1) and 10-O-beta-D-glucopyranoside-oplopanone (2), along with seven known compounds, were isolated from the aerial part of Aster flaccidus (composite), a traditional Chinese herb medicine. The structures of 1 and 2 were established by spectroscopic methods, especially 2D NMR experiments.

  15. Nine new secoiridoid glucosides from Jasminum nudiflorum.

    PubMed

    Takenaka, Yukiko; Tanahashi, Takao; Taguchi, Hiromi; Nagakura, Naotaka; Nish, Toyoyuki

    2002-03-01

    Phytochemical study of the leaves of Jasminum nudiflorum has led to the isolation of nine new secoiridoid glucosides, jasnudiflosides F-L (1-7), nudifloside D (8) and isooleoacteoside (9). The structures of these compounds were elucidated on the basis of chemical and spectroscopic evidence.

  16. Three secoiridoid glucosides from Jasminum nudiflorum.

    PubMed

    Tanahashi, T; Takenaka, Y; Nagakura, N; Nishi, T

    1999-09-01

    Phytochemical study of the leaves and stems of Jasminum nudiflorum has led to the isolation of three secoiridoid glucosides, jasnudiflosides A-C (1-3). The structures of these compounds were elucidated on the basis of chemical and spectroscopic evidence.

  17. New secoiridoid glucosides from Jasminum lanceolarium.

    PubMed

    Shen, Y C; Lin, S L

    1996-12-01

    Two new secoiridoid glucosides, the trans-P-coumaroyl and trans-feruloyl esters of 10-hydroxyoleoside, jaslanceosides A (2) and B (3), were isolated from the leaves and stems of Jasminum lanceolarium (Oleaceae) in addition to jasminoside (1) and 10-hydroxyoleoside dimethyl ester (8). The structures of these compounds have been elucidated on the basis of spectral and chemical methods.

  18. The dimers of cyanamide

    NASA Astrophysics Data System (ADS)

    Moffat, J. B.

    Ab initio calculations have been performed on various dimeric forms of cyanamide. The "nondissociative" dimerization of cyanamide leads to cyclic molecules all of which are unstable with respect to cyanamide. However, the molecules produced by "dissociative" dimerization are stable relative to cyanamide. Dicyandiamide is found to be the most stable of nine dimeric configurations.

  19. Biosynthesis of cholesteryl glucoside by Mycoplasma gallinarum.

    PubMed

    Smith, P F

    1971-12-01

    The biosynthesis of cholesteryl glucoside by Mycoplasma gallinarum strain J proceeds by the transfer of glucose from uridine-5'-diphosphoglucose to membrane-bound sterol. Galactose also can be coupled to cholesterol via uridine-5'-diphosphogalactose. The reaction is specific for the uridine-5'-diphospho sugars. Enzymatic activity is associated with the membrane. Treatment of the membrane to remove endogenous sterol inactivates the enzyme. Only sterol which has been bound to the membrane participates in the reaction. The optimum pH is about 8.0, and Mg(2+) is required. The reaction is unaffected by nucleotide triphosphate, uridine-5'-monophosphate, and uridine-5'-diphosphate. Reduction of pH to the optimum for beta-glucosidase in the membrane results in loss of synthesized glucoside. The enzyme is saturated at 0.5 mm uridine-5'-diphosphoglucose. The apparent K(m) of 2.05 x 10(-7) indicates a high affinity of the enzyme for the nucleotide sugar.

  20. RNA Dimerization Promotes PKR Dimerization and Activation

    PubMed Central

    Heinicke, Laurie A.; Wong, C. Jason; Lary, Jeffrey; Nallagatla, Subba Rao; Diegelman-Parente, Amy; Zheng, Xiaofeng; Cole, James L.; Bevilacqua, Philip C.

    2009-01-01

    The double-stranded RNA (dsRNA)-activated protein kinase (PKR) plays a major role in the innate immune response in humans. PKR binds dsRNA non-sequence specifically and requires a minimum of 15 bp dsRNA for one protein to bind and 30 bp dsRNA to induce protein dimerization and activation by autophosphorylation. PKR phosphorylates eIF2α, a translation initiation factor, resulting in the inhibition of protein synthesis. We investigated the mechanism of PKR activation by an RNA hairpin with a number of base pairs intermediate between these 15 to 30 bp limits: HIV-I TAR RNA, a 23 bp hairpin with three bulges that is known to dimerize. To test whether RNA dimerization affects PKR dimerization and activation, TAR monomers and dimers were isolated from native gels and assayed for RNA and protein dimerization. To modulate the extent of dimerization, we included TAR mutants with different secondary features. Native gel mixing experiments and analytical ultracentrifugation indicate that TAR monomers bind one PKR monomer and that TAR dimers bind two or three PKRs, demonstrating that RNA dimerization drives the binding of multiple PKR molecules. Consistent with functional dimerization of PKR, TAR dimers activated PKR while TAR monomers did not, and RNA dimers with fewer asymmetrical secondary structure defects, as determined by enzymatic structure mapping, were more potent activators. Thus, the secondary structure defects in the TAR RNA stem function as antideterminants to PKR binding and activation. Our studies support that dimerization of a 15–30 bp hairpin RNA, which effectively doubles its length, is a key step in driving activation of PKR and provide a model for how RNA folding can be related to human disease. PMID:19445956

  1. A new sesquilignan glucoside from Uraria sinensis.

    PubMed

    Yang, Yingda; Hu, Zhengxi; Luo, Zengwei; Xue, Yongbo; Yao, Guangmin; Wang, Yanyan; Zhang, Yonghui

    2014-01-17

    A new sesquilignan glucoside, urariasinoside A (1), together with eight known compounds, including two lignans, a sesquilignan, a dilignan, and four flavonoid derivatives were isolated from the aerial parts of Uraria sinensis. Their structures were determined on the basis of extensive spectroscopic analyses and comparison with literature data. Compound 1 was evaluated for in vitro cytotoxicity activity against HL-60, SMMC-7721, A549, MCF-7, SW480, and BEAS-2B cell lines.

  2. Lignan glucosides from Sinomenium acutum rhizomes.

    PubMed

    Kim, Ki Hyun; Moon, Sae Rom; Kim, Chung Sub; Woo, Kyeong Wan; Choi, Sang Un; Lee, Kang Ro

    2013-01-01

    The new lignan glucoside, acutumoside (1), was isolated from Sinomenium acutum rhizomes together with nine known compounds (2-10). The structure of 1 was elucidated on the basis of extensive spectroscopic analyses, including two-dimensional nuclear magnetic resonance and chemical reactions. Compounds 2, 7, 8, and 10 displayed potential antiproliferative activity against A549, SK-OV-3, SK-MEL-2, and HCT-15 cell lines, while compound 1 showed weak activity against these human tumor cells.

  3. Aromatic compound glucosides, alkyl glucoside and glucide from the fruit of anise.

    PubMed

    Fujimatu, Eiko; Ishikawa, Toru; Kitajima, Junichi

    2003-07-01

    From the polar portion of the methanolic extract of the fruit of anise (Pimpinella anisum L.), which has been used as a spice and medicine since antiquity, four aromatic compound glucosides, an alkyl glucoside and a glucide were isolated together with 24 known compounds. The structures of the new compounds were clarified as (E)-3-hydroxyanethole beta-D-glucopyranoside, (E)-1'-(2-hydroxy-5-methoxyphenyl)propane beta-D-glucopyranoside, 3-hydroxyestragole beta-D-glucopyranoside, methyl syringate 4-O-beta-D-glucopyranoside, hexane-1,5-diol 1-O-beta-D-glucopyranoside and 1-deoxy-L-erythritol 3-O-beta-D-glucopyranoside by spectral investigation.

  4. λ-Radiolysis of aqueous solution of glucosides

    NASA Astrophysics Data System (ADS)

    Rongyao, Yuan; Jilan, Wu

    In this paper, three types of aqueous solution of glucoside, baicalin (I), 1, 8-dihydroxyanthraquinone-β-D-glucoside (II) and glycyrrhizin (III), have been investigated. The yields of decomposition of glucosides are determined. Their G values decrease as doses increase. Some radiolysis products are identified. The influences of different radical scavengers such as, O 2, N 2O, KCNS and isopropanol, are observed. Radiolysis is mainly caused by OH radical. Radiation induced hydrolysis of glucosidic linkage is not the main process, the proportions of dissociated aglycon to total radiolysis products are less than 10%.

  5. Universality in fermionic dimer-dimer scattering

    NASA Astrophysics Data System (ADS)

    Deltuva, A.

    2017-08-01

    Collisions of two fermionic dimers near the unitary limit are studied using exact four-particle equations for transition operators in momentum space. Universal properties of dimer-dimer phase shifts and effective range expansion (ERE) parameters are determined. The inclusion of the fourth-order momentum term in the ERE significantly extends its validity to higher collision energies. The dimer-dimer scattering length and effective range are determined in the unitary limit as well as their corrections arising due to the finite range of the two-fermion interaction. These results are of considerably higher accuracy as compared to previous works, but confirm most of the previous results except for the lattice effective field theory calculations.

  6. A new phenylethanoid glucoside from Jacaranda mimosifolia.

    PubMed

    Rana, Ajay; Bhangalia, Shalika; Singh, Harsh Pratap

    2013-01-01

    This study reports the isolation of a new phenylethanoid glucoside (1) from the leaves of Jacaranda mimosifolia along with jacaranone (2), followed by the comparative estimation of total antioxidant compounds, total polyphenols and total flavonoids from different solvent extracts of the leaves and flowers. The total antioxidant activity was evaluated by both DPPH and ABTS free-radical scavenging assay methods from different solvent extracts of J. mimosifolia leaves and flowers. The antioxidant activities of the purified compounds (1 and 2) were detected by DPPH-TLC method.

  7. Sesinoside, a new iridoid glucoside from sesame (Sesamum indicum) seedlings.

    PubMed

    Takase, Ryo; Hasegawa, Tsuyoshi; Yamada, Kosumi; Hasegawa, Koji; Shigemori, Hideyuki

    2014-11-01

    A new iridoid glucoside, sesinoside (1), was isolated from the seedlings of Sesamum indicum. The structure of 1 was elucidated by spectroscopic analyses and by methanolysis of 1, which produced the known compounds, phlorigidosides C (2) and (6Z)-foliamenthic acid methyl ester (3). This is the first report of an iridoid glucoside with 3.

  8. A new acylated isoflavone glucoside from Pterocarpus santalinus.

    PubMed

    Krishnaveni, K S; Srinivasa Rao, J V

    2000-09-01

    Phytochemical investigation on the constituents of heartwood of Pterocarpus santalinus resulted in the isolation of a new acylated isoflavone glucoside. The structure of the new compound was elucidated on the basis of spectral studies as 4',5-dihydroxy-7-O-methyl isoflavone 3'-O-D-(3''-E-cinnamoyl)glucoside.

  9. New jacaranone glucoside from Jacaranda oxyphylla leaves.

    PubMed

    Pereira, V V; Duarte, L P; Silva, R R; Takahashi, J A

    2016-11-01

    Jacaranda oxyphylla Cham. is popularly known as 'caroba-de-São-Paulo' and it is used in traditional medicine for microbial infections. A new phytoquinoid (α/β-glucoside-4-phenylacetate-6-(1-hydroxy-4-oxo-2,5-cyclohexadiene-1-acetate) (1) was isolated from J. oxyphylla leaves, together with three known compounds: quercetin-3-O-β-d-galactoside (2), verbascoside (3) and polystyrene (4). Their chemical structures were elucidated using spectroscopic techniques and by comparison with the related known compounds. In addition, it was found a pronounced acetylcholinesterase inhibitory activity for the quinoid 1 (100.0 ± 0.8%) and phenolic compounds 2 and 3 (99.9 ± 0.7 and 99.3 ± 0.5%, respectively), if compared to the standard eserine (92.7 ± 0.4%), that was analysed by a microplate spectrophotometer.

  10. The Biosynthesis of Steryl Glucosides in Plants 1

    PubMed Central

    Ongun, Alpaslan; Mudd, J. B.

    1970-01-01

    Mitochondrial preparations from pea root (Pisum sativum L. var. Alaska) cauliflower inflorescence (Brassica cauliflora Gars.) and avocado inner mesocarp (Persea americana Mill. var. Fuerte), and chloroplast preparations from spinach leaf (Spinacia oleracea L. var. Bloomsdale) incorporate glucose into steryl glucoside and acylated steryl glucoside when either uridine diphosphate-glucose or uridine diphosphate-galactose is supplied as precursor. In the case of pea root mitochondria, galactosyl diglycerides are not formed from either nucleotide sugar. In the case of spinach chloroplasts only 3% of the metabolized uridine diphosphate-galactose is found as steryl glycosides. Time course experiments indicate that the steryl glucoside is the precursor of the acylated steryl glucoside. The effect of pH on the over-all reaction and analysis of the reaction products suggest that the glucosylation of the sterol has a pH optimum of 8 to 9, and the pH optimum for the acylation of the steryl glucoside is 6.5 to 7. The synthesis of steryl glucoside and acylated steryl glucoside, catalyzed by acetone powders of pea root mitochondria, is stimuated by added sitosterol and stigmasterol. Images PMID:5423466

  11. 21 CFR 172.816 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Methyl glucoside-coconut oil ester. 172.816... § 172.816 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester may be safely used in food in accordance with the following conditions: (a) It is the methyl glucoside-coconut oil ester...

  12. Iridoid glucosides in the genus Veronica (Plantaginaceae) from New Zealand.

    PubMed

    Kroll-Møller, Phillip; Pedersen, Katja D; Gousiadou, Chrysoula; Kokubun, Tetsuo; Albach, Dirk; Taskova, Rilka; Garnock-Jones, Phil J; Gotfredsen, Charlotte H; Jensen, Søren Rosendal

    2017-08-01

    Four simple iridoid glucosides, three known esters of catalpol, seven esters of aucubin, and two phenylethanoids were isolated from Veronica hookeri (syn. Hebe ciliolata; Plantaginaceae). Of these, none of four aromatic (p-methoxybenzoyl, isovanilloyl, veratroyl, caffeoyl) 6-O-esters of aucubin and 6″-O-benzoyl mussaenosidic acid, had been reported from nature before. Similarly, three simple iridoid glucosides, two esters of 6-O-rhamnopyranosylcatapol, and two phenylethanoid glucosides, as well as 1-O-benzoyl-3-α-glucuronosylglycerol, and 1-O-β-benzoyl rutinoside were isolated from Veronica pinguifolia (syn. Hebe pinguifolia). The compound 3″-O-benzoyl-2″-O-caffeoyl 6-O-rhamnopyranosylcatalpol had not been reported previously. The pattern of the structural features of the iridoid glucosides is overlaid onto the latest molecular phylogenetic framework of Veronica sects. Hebe and Labiatoides, and discussed in the context of evolutionary trends. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Photochemical dimerization of organic compounds

    DOEpatents

    Crabtree, Robert H.; Brown, Stephen H.; Muedas, Cesar A.; Ferguson, Richard R.

    1992-01-01

    At least one of selectivity and reaction rate of photosensitized vapor phase dimerizations, including dehydrodimerizations, hydrodimerizations and cross-dimerizations of saturated and unsaturated organic compounds is improved by conducting the dimerization in the presence of hydrogen or nitrous oxide.

  14. Synthesis and SAR of Thiazolylmethylphenyl Glucoside as Novel C-Aryl Glucoside SGLT2 Inhibitors

    PubMed Central

    2010-01-01

    Novel C-aryl glucoside SGLT2 inhibitors containing the thiazole motif were designed and synthesized for biological evaluation. Among the compounds assayed, thiazole containing furanyl moiety 14v and thiophenyl moiety 14y demonstrated the best in vitro inhibitory activity against SGLT2 in this series to date (IC50 = 0.720 nM for 14v and IC50 = 0.772 nM for 14y). Both of these compounds have been further evaluated on a urinary glucose excretion test and the urine volumes excreted. PMID:24900297

  15. Cyanidin 3-glucoside and peonidin 3-glucoside inhibit tumor cell growth and induce apoptosis in vitro and suppress tumor growth in vivo.

    PubMed

    Chen, Pei-Ni; Chu, Shu-Chen; Chiou, Hui-Ling; Chiang, Chui-Liang; Yang, Shun-Fa; Hsieh, Yih-Shou

    2005-01-01

    Dietary polyphenols, including anthocyanins, are suggested to be involved in the protective effects of fruits and vegetables against cancer. However, anticancer effects of peonidin 3-glucoside have not been clearly demonstrated, with only limited studies being available concerning the inhibitory effect of cyanidin 3-glucoside for tumor cell growth. Therefore, in this study, we have isolated and identified the two bioactive compounds, peonidin 3-glucoside and cyanidin 3-glucoside, from Oryza sativa L. indica, to treat various cancer cells. The results showed that, among analyzed cell lines, HS578T was the most sensitive to peonidin 3-glucoside and cyanidin 3-glucoside. Treatment with peonidin 3-glucoside or cyanidin 3-glucoside resulted in a strong inhibitory effect on cell growth via G2/M arrest. Regarding cell cyclerelated proteins, peonidin 3-glucoside treatment resulted in down-regulation of protein levels of cyclin-dependent kinase (CDK)-1, CDK-2, cyclin B1, and cyclin E, whereas cyanidin 3-glucoside could decrease the protein levels of CDK-1, CDK-2, cyclin B1, and cyclin D1. In addition, cyanidin 3-glucoside or peonidin 3-glucoside also induced caspase-3 activation, chromatin condensation, and cell death. Furthermore, anthocyanins from O. sativa L. indica were evidenced by their inhibition on the growth of Lewis lung carcinoma cells in vivo.

  16. Protein dimerization. Inside job.

    PubMed

    Metzger, H

    1994-04-01

    In a sophisticated combination of genetic engineering and organic synthesis, a general method for dimerizing recombinant intracellular proteins has been devised; the usefulness of the method should now be testable.

  17. Dimers in nucleating vapors

    NASA Astrophysics Data System (ADS)

    Lushnikov, A. A.; Kulmala, M.

    1998-09-01

    The dimer stage of nucleation may affect considerably the rate of the nucleation process at high supersaturation of the nucleating vapor. Assuming that the dimer formation limits the nucleation rate, the kinetics of the particle formation-growth process is studied starting with the definition of dimers as bound states of two associating molecules. The partition function of dimer states is calculated by summing the Boltzmann factor over all classical bound states, and the equilibrium population of dimers is found for two types of intermolecular forces: the Lennard-Jones (LJ) and rectangular well+hard core (RW) potentials. The principle of detailed balance is used for calculating the evaporation rate of dimers. The kinetics of the particle formation-growth process is then investigated under the assumption that the trimers are stable with respect to evaporation and that the condensation rate is a power function of the particle mass. If the power exponent λ=n/(n+1) (n is a non-negative integer), the kinetics of the process is described by a finite set of moments of particle mass distribution. When the characteristic time of the particle formation by nucleation is much shorter than that of the condensational growth, n+2 universal functions of a nondimensional time define the kinetic process. These functions are calculated for λ=2/3 (gas-to-particle conversion in the free molecular regime) and λ=1/2 (formation of islands on surfaces).

  18. Nicotinamide metabolism in ferns: formation of nicotinic acid glucoside.

    PubMed

    Ashihara, Hiroshi; Yin, Yuling; Watanabe, Shin

    2011-03-01

    The metabolic fate of [carbonyl-(14)C]nicotinamide was investigated in 9 fern species, Psilotum nudum, Angiopteris evecta, Lygodium japonicum, Acrostichum aureum, Asplenium antiquum, Diplazium subsinuatum, Thelypteris acuminate, Blechnum orientale and Crytomium fortune. All fern species produce a large quantity of nicotinic acid glucoside from [(14)C]nicotinamide, but trigonelline formation is very low. Increases in the release of (14)CO(2) with incubation time was accompanied by decreases in [carboxyl-(14)C]nicotinic acid glucoside. There was slight stimulation of nicotinic acid glucoside formation by 250 mM NaCl in mature leaves of the mangrove fern, Acrostichum aureum, but it is unlikely that this compound acts as a compatible solute. Nicotinamide and nicotinic acid salvage for pyridine nucleotide synthesis was detected in all fern species, although this activity was always less than nicotinic acid glucoside synthesis. Predominant formation of nicotinic acid glucoside is characteristic of nicotinic acid metabolism in ferns. This reaction appears to act as a detoxication mechanism, removing excess nicotinic acid.

  19. Evaluation of dihydroquercetin-3-O-glucoside from Malbec grapes as copigment of malvidin-3-O-glucoside.

    PubMed

    Fanzone, Martín; González-Manzano, Susana; Pérez-Alonso, Joaquín; Escribano-Bailón, María Teresa; Jofré, Viviana; Assof, Mariela; Santos-Buelga, Celestino

    2015-05-15

    Malbec is a wine grape variety of great phenolic potential characterized for its high levels of anthocyanins and dihydroflavonols. To evaluate the possible implication of dihydroflavonols in the expression of red wine color through reactions of copigmentation or condensation, assays were carried out in wine model systems with different malvidin-3-O-glucoside:dihydroquercetin-3-O-glucoside molar ratios. The addition of increasing levels of dihydroquercetin-3-O-glucoside to a constant malvidin-3-O-glucoside concentration resulted in a hyperchromic effect associated with a darkening of the anthocyanin solutions, greater quantity of color and visual saturation, perceptible to the human eye. Copigmentation and thermodynamic measurements showed that dihydroquercetin-3-O-glucoside can act as an anthocyanin copigment, similar to other usual wine components like flavanols or phenolic acids, although apparently less efficient than flavonols. The high levels of dihydroflavonols existing in Malbec wines in relation to other non-anthocyanin phenolics should make this family of compounds particularly important to explain the color expression in Malbec young red wines.

  20. Glycine Transporter Dimers

    PubMed Central

    Bartholomäus, Ingo; Milan-Lobo, Laura; Nicke, Annette; Dutertre, Sébastien; Hastrup, Hanne; Jha, Alok; Gether, Ulrik; Sitte, Harald H.; Betz, Heinrich; Eulenburg, Volker

    2015-01-01

    Different Na+/Cl−-dependent neurotransmitter transporters of the SLC6a family have been shown to form dimers or oligomers in both intracellular compartments and at the cell surface. In contrast, the glycine transporters (GlyTs) GlyT1 and -2 have been reported to exist as monomers in the plasma membrane based on hydrodynamic and native gel electrophoretic studies. Here, we used cysteine substitution and oxidative cross-linking to show that of GlyT1 and GlyT2 also form dimeric complexes within the plasma membrane. GlyT oligomerization at the cell surface was confirmed for both GlyT1 and GlyT2 by fluorescence resonance energy transfer microscopy. Endoglycosidase treatment and surface biotinylation further revealed that complex-glycosylated GlyTs form dimers located at the cell surface. Furthermore, substitution of tryptophan 469 of GlyT2 by an arginine generated a transporter deficient in dimerization that was retained intracellulary. Based on these results and GlyT structures modeled by using the crystal structure of the bacterial homolog LeuTAa, as a template, residues located within the extracellular loop 3 and at the beginning of transmembrane domain 6 are proposed to contribute to the dimerization interface of GlyTs. PMID:18252709

  1. Biosynthesis of the Nitrile Glucosides Rhodiocyanoside A and D and the Cyanogenic Glucosides Lotaustralin and Linamarin in Lotus japonicus1

    PubMed Central

    Forslund, Karin; Morant, Marc; Jørgensen, Bodil; Olsen, Carl Erik; Asamizu, Erika; Sato, Shusei; Tabata, Satoshi; Bak, Søren

    2004-01-01

    Lotus japonicus was shown to contain the two nitrile glucosides rhodiocyanoside A and rhodiocyanoside D as well as the cyanogenic glucosides linamarin and lotaustralin. The content of cyanogenic and nitrile glucosides in L. japonicus depends on plant developmental stage and tissue. The cyanide potential is highest in young seedlings and in apical leaves of mature plants. Roots and seeds are acyanogenic. Biosynthetic studies using radioisotopes demonstrated that lotaustralin, rhodiocyanoside A, and rhodiocyanoside D are derived from the amino acid l-Ile, whereas linamarin is derived from Val. In silico homology searches identified two cytochromes P450 designated CYP79D3 and CYP79D4 in L. japonicus. The two cytochromes P450 are 94% identical at the amino acid level and both catalyze the conversion of Val and Ile to the corresponding aldoximes in biosynthesis of cyanogenic glucosides and nitrile glucosides in L. japonicus. CYP79D3 and CYP79D4 are differentially expressed. CYP79D3 is exclusively expressed in aerial parts and CYP79D4 in roots. Recombinantly expressed CYP79D3 and CYP79D4 in yeast cells showed higher catalytic efficiency with l-Ile as substrate than with l-Val, in agreement with lotaustralin and rhodiocyanoside A and D being the major cyanogenic and nitrile glucosides in L. japonicus. Ectopic expression of CYP79D2 from cassava (Manihot esculenta Crantz.) in L. japonicus resulted in a 5- to 20-fold increase of linamarin content, whereas the relative amounts of lotaustralin and rhodiocyanoside A/D were unaltered. PMID:15122013

  2. Superbackscattering nanoparticle dimers.

    PubMed

    Liberal, Iñigo; Ederra, Iñigo; Gonzalo, Ramón; Ziolkowski, Richard W

    2015-07-10

    The theory and design of superbackscattering nanoparticle dimers are presented. We analytically derive the optimal configurations and the upper bound of their backscattering cross-sections. In particular, it is demonstrated that electrically small nanoparticle dimers can enhance the backscattering by a factor of 6.25 with respect to single dipolar particles. We demonstrate that optimal designs approaching this theoretical limit can be found by using a simple circuit model. The study of practical implementations based on plasmonic and high-permittivity particles has been also addressed. Moreover, the numerical examples reveal that the dimers can attain close to a fourfold enhancement of the single nanoparticle response even in the presence of high losses.

  3. Collective motion of dimers.

    PubMed

    Penington, Catherine J; Korvasová, Karolína; Hughes, Barry D; Landman, Kerry A

    2012-11-01

    We consider a discrete agent-based model on a one-dimensional lattice and a two-dimensional square lattice, where each agent is a dimer occupying two sites. Agents move by vacating one occupied site in favor of a nearest-neighbor site and obey either a strict simple exclusion rule or a weaker constraint that permits partial overlaps between dimers. Using indicator variables and careful probability arguments, a discrete-time master equation for these processes is derived systematically within a mean-field approximation. In the continuum limit, nonlinear diffusion equations that describe the average agent occupancy of the dimer population are obtained. In addition, we show that multiple species of interacting subpopulations give rise to advection-diffusion equations. Averaged discrete simulation data compares very well with the solution to the continuum partial differential equation models. Since many cell types are elongated rather than circular, this work offers insight into population-level behavior of collective cellular motion.

  4. 21 CFR 573.660 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.660 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Methyl glucoside-coconut oil ester. 573.660...

  5. 21 CFR 573.660 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.660 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Methyl glucoside-coconut oil ester. 573.660...

  6. 21 CFR 573.660 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.660 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Methyl glucoside-coconut oil ester. 573.660...

  7. 21 CFR 573.660 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.660 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Methyl glucoside-coconut oil ester. 573.660...

  8. 21 CFR 178.3600 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Methyl glucoside-coconut oil ester. 178.3600... SANITIZERS Certain Adjuvants and Production Aids § 178.3600 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester identified in § 172.816(a) of this chapter may be safely used as a...

  9. 21 CFR 172.816 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Methyl glucoside-coconut oil ester. 172.816 Section... HUMAN CONSUMPTION Multipurpose Additives § 172.816 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester may be safely used in food in accordance with the following conditions: (a) It is...

  10. Intestinal bacterium Eubacterium cellulosolvens deglycosylates flavonoid C- and O-glucosides.

    PubMed

    Braune, Annett; Blaut, Michael

    2012-11-01

    Eubacterium cellulosolvens cleaved the flavone C-glucosides homoorientin and isovitexin to their aglycones luteolin and apigenin, respectively. The corresponding isomers, orientin and vitexin, or other polyphenolic C-glucosides were not deglycosylated. E. cellulosolvens also cleaved several O-coupled glucosides of flavones and isoflavones to their corresponding aglycones.

  11. 21 CFR 178.3600 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Methyl glucoside-coconut oil ester. 178.3600... SANITIZERS Certain Adjuvants and Production Aids § 178.3600 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester identified in § 172.816(a) of this chapter may be safely used as a processing...

  12. 21 CFR 178.3600 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Methyl glucoside-coconut oil ester. 178.3600 Section 178.3600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Production Aids § 178.3600 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester identified...

  13. 21 CFR 178.3600 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Methyl glucoside-coconut oil ester. 178.3600... SANITIZERS Certain Adjuvants and Production Aids § 178.3600 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester identified in § 172.816(a) of this chapter may be safely used as a processing...

  14. 21 CFR 172.816 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Methyl glucoside-coconut oil ester. 172.816... HUMAN CONSUMPTION Multipurpose Additives § 172.816 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester may be safely used in food in accordance with the following conditions: (a) It is the...

  15. 21 CFR 172.816 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Methyl glucoside-coconut oil ester. 172.816... HUMAN CONSUMPTION Multipurpose Additives § 172.816 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester may be safely used in food in accordance with the following conditions: (a) It is the...

  16. 21 CFR 172.816 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Methyl glucoside-coconut oil ester. 172.816... HUMAN CONSUMPTION Multipurpose Additives § 172.816 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester may be safely used in food in accordance with the following conditions: (a) It is the...

  17. 21 CFR 178.3600 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Methyl glucoside-coconut oil ester. 178.3600... SANITIZERS Certain Adjuvants and Production Aids § 178.3600 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester identified in § 172.816(a) of this chapter may be safely used as a processing...

  18. Antibacterial galloylated alkylphloroglucinol glucosides from myrtle (Myrtus communis).

    PubMed

    Appendino, Giovanni; Maxia, Lucia; Bettoni, Piergiorgio; Locatelli, Monica; Valdivia, Carola; Ballero, Mauro; Stavri, Michael; Gibbons, Simon; Sterner, Olov

    2006-02-01

    An investigation of the polar glycosidic fraction from the leaves of myrtle afforded four galloylated nonprenylated phloroglucinol glucosides (3a-d) related to the endoperoxide hormone G3 (4) in terms of structure and biogenesis. Despite their close similarity, significant antibacterial activity was shown only by one of these compounds (3b, gallomyrtucommulone B), while the G3 hormone (4) was inactive.

  19. Four new trimeric stilbene glucosides from Welwitschia mirabilis.

    PubMed

    Murata, Hiroko; Iliya, Ibrahim; Tanaka, Toshiyuki; Furasawa, Miyuki; Ito, Tetsuro; Nakaya, Ken-ichi; Oyama, Mayoshi; Iinuma, Munekazu

    2005-06-01

    Four new trimeric stilbene glucosides, mirabilosides C-F (1-4) were isolated from MeOH extract of stem and root of Welwitschia mirabilis (Welwitschiaceae) along with three known stilbenoids, resveratrol (5), gnemonoside B (6), and gnetin G (7). The structures of these compounds were elucidated by spectroscopic methods.

  20. Three phenylethanoid glucosides of unusual structure from Chirita sinensis (Gesneriaceae).

    PubMed

    Damtoft, S; Jensen, S R

    1994-09-01

    From Chirita sinensis (Gesneriaceae) was isolated six phenylethanoid glucosides, namely the previously known positional isomers plantainoside A, calceolarioside A and calceolarioside B together with three new compounds named chiritoside A, B and C. It was proved by analysis of the NMR data that the chiritosides were the 4"-O-beta-glucopyranosyl-derivatives of the first three compounds.

  1. Water-soluble constituents of cumin: monoterpenoid glucosides.

    PubMed

    Ishikawa, Toru; Takayanagi, Tomomi; Kitajima, Junichi

    2002-11-01

    From the water-soluble portion of the methanol extract of cumin (fruit of Cuminum cyminum L.), which has been used as a spice and medicine since antiquity, sixteen monoterpenoid glucosides, including twelve new compounds, were isolated. Their structures were clarified by spectral investigation.

  2. Enzymatic Synthesis of Acylphloroglucinol 3-C-Glucosides from 2-O-Glucosides using a C-Glycosyltransferase from Mangifera indica.

    PubMed

    Chen, Dawei; Sun, Lili; Chen, Ridao; Xie, Kebo; Yang, Lin; Dai, Jungui

    2016-04-18

    A green and cost-effective process for the convenient synthesis of acylphloroglucinol 3-C-glucosides from 2-O-glucosides was exploited using a novel C-glycosyltransferase (MiCGTb) from Mangifera indica. Compared with previously characterized CGTs, MiCGTb exhibited unique de-O-glucosylation promiscuity and high regioselectivity toward structurally diverse 2-O-glucosides of acylphloroglucinol and achieved high yields of C-glucosides even with a catalytic amount of uridine 5'-diphosphate (UDP). These findings demonstrate for the first time the significant potential of a single-enzyme approach to the synthesis of bioactive C-glucosides from both natural and unnatural acylphloroglucinol 2-O-glucosides.

  3. Recent Developments of C-Aryl Glucoside SGLT2 Inhibitors.

    PubMed

    Zhang, Yang; Liu, Zhao-Peng

    2016-01-01

    Sodium-glucose cotransporter 2 (SGLT2) is almost exclusively expressed in the proximal renal tubules. It is responsible for about 90% of the glucose reabsorption from tubular fluid. Selective inhibition of SGLT2 is expected to favor in the normalization of plasma glucose levels in T2DM patients through the prevention of renal glucose reabsorption and the promotion of glucose excretion from urine. Selective SGLT2 inhibitors have the merits to minimize the gastrointestinal side effects associated with SGLT1 inhibition, and selective SGLT2 inhibition may have a low risk of hypoglycemia. Since the C-aryl glucosides are metabolically more stable than the O-glucosides, numerous efforts have been made in the development of potent and selective C-aryl glucoside SGLT2 inhibitors, and a number of them are now used as anti-diabetes drugs in clinic or at various stages of clinical developments. Based on their structural features, in this review, these SGLT2 inhibitors are classified as three types: the phenyl/arylmethylphenyl C-glucosides, with an emphasis on the modifications on the proximal and/or the distal phenyl ring, and the spacer; the heteroarylmethylphenyl Cglucosides, with a replacement of the distal phenyl ring by a heterocycle like pyridazine, pyrimidine, thiophene and benzothiophene, thiazole, 1,3,4-thiadiazole, and triazolopyridinone; and the glucose-modified Caryl glucosides, including the glucose C-1 derived O-spiroketals, C-4 gem-difluoro analogues, C-5 and C-6 modified derivatives, dioxa-bicyclo[3.2.1]octane bridged ketals, the thioglucosides, and carbasugars. The structure-activity relationships (SARs) of each type along with their inhibitory potency against human SGLT2 and selectivity over human SGLT1 are discussed.

  4. Isolation and purification of closely related citrus limonoid glucosides by flash chromatography.

    PubMed

    Raman, Girija; Cho, Minhee; Brodbelt, Jennifer S; Patil, Bhimanagouda S

    2005-01-01

    Several citrus limonoid glycosides have proved to be particularly difficult to purify using conventional techniques. A reversed-phase flash chromatographic technique has been developed for the separation and isolation of the closely related limonoid glucosides, nomilin 17-beta-D-glucopyranoside and nomilinic acid 17-beta-D-glucopyranoside, with confirmation of their identities by electrospray ionisation mass spectrometry. Furthermore, the semi-purification of the mixture of glucosides enriched with flavanone glucosides such as naringin, narirutin and other limonoid glucosides was obtained. The closely eluting glucosides were successfully separated to achieve a good yield and purity of 93%.

  5. Quantum Dimer Model: Phase Diagrams

    NASA Astrophysics Data System (ADS)

    Goldstein, Garry; Chamon, Claudio; Castelnovo, Claudio

    We present new theoretical analysis of the Quantum Dimer Model. We study dimer models on square, cubic and triangular lattices and we reproduce their phase diagrams (which were previously known only numerically). We show that there are several types of dimer liquids and solids. We present preliminary analysis of several other models including doped dimers and planar spin ice, and some results on the Kagome and hexagonal lattices.

  6. Conjugates of a secoiridoid glucoside with a phenolic glucoside from the flower buds of Lonicera japonica Thunb.

    PubMed

    Kashiwada, Yoshiki; Omichi, Yuka; Kurimoto, Shin-ichiro; Shibata, Hirofumi; Miyake, Yoshiyuki; Kirimoto, Tsukasa; Takaishi, Yoshihisa

    2013-12-01

    Secoiridoid glucosides, including two conjugates with a phenolic and two conjugates with a nicotinic acid derivative (3 and 4), together with seven known secoiridoid derivatives, were isolated from flower buds of Lonicera japonica. The structures were elucidated by spectroscopic analyses. Anti-influenza activities of six isolated compounds were also evaluated by plaque assay and neuraminidase inhibitory assay.

  7. Evidence for dimerization of dimers in K+ channel assembly.

    PubMed Central

    Tu, L; Deutsch, C

    1999-01-01

    Voltage-gated K+ channels are tetrameric, but how the four subunits assemble is not known. We analyzed inactivation kinetics and peak current levels elicited for a variety of wild-type and mutant Kv1.3 subunits, expressed singly, in combination, and as tandem constructs, to show that 1) the dominant pathway involves a dimerization of dimers, and 2) dimer-dimer interaction may involve interaction sites that differ from those involved in monomer-monomer association. Moreover, using nondenaturing gel electrophoresis, we detected dimers and tetramers, but not trimers, in the translation reaction of Kv1.3 monomers. PMID:10096897

  8. Proanthocyanidin profile of cowpea (Vigna unguiculata) reveals catechin-O-glucoside as the dominant compound.

    PubMed

    Ojwang, Leonnard O; Yang, Liyi; Dykes, Linda; Awika, Joseph

    2013-08-15

    Proanthocyanidin (PA) profile and content can have important nutritional and health implications on plant foods. Six diverse cowpea phenotypes (black, red, green, white, light-brown and golden-brown) were investigated for PA composition using normal-phase HPLC and reversed-phase UPLC-TQD-MS. Catechin and (epi)afzelechin were the major flavan-3-ol units. Unusual composition was observed in all cowpea phenotypes with significant degrees of glycosylation in the monomers and dimers. The PA content of cowpea (dry basis) ranged between 2.2 and 6.3 mg/g. Monomeric flavan-3-ols were the largest group of PA (36-69%) in cowpea, with catechin-7-O-glucoside accounting for most (about 88%) of the monomers. The oligomers with degree of polymerization (DP) 2-4 ranged from 0.41 to 1.3 mg/g (15-20%), whereas DP>10 polymers accounted for only 13.5% of PA. Future studies that highlight the impact of the unusual cowpea PA profile on nutritional and bioactive properties of this important legume are warranted. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. [Mechanism of amylase action on glucoside starch bonds].

    PubMed

    Zherebtsov, N A; Zabelina, L F; Ektoba, A I

    1976-12-01

    Functional groups of glucoamylase and alpha-amylase from Asp. awamori, alpha-amylase from Asp. oryzae and alpha- and beta-amylases from barley malt are identified. Kinetic curves of the activity dependency on pH, values of ionization heats and photooxidative inactivation draw to the conclusion that carboxyl-imidazole system enters into the active site of the enzymes. A hypothetic mechanism of hydrolysis of alpha-1,4-glucoside bond in starch molecule by alpha- and beta-amylases and of alpha-1,4- and alpha-1,6-glucoside bonds by glucoamylase is given. A theory of induced correspondence of enzyme and substrate satisfactorily explains the specificity of the enzyme action and the cause of complete starch convertion into glucose under glucoamylase action and of terminal starch hydrolysis by alpha- and beta-amylases.

  10. A new cytotoxic acylated apigenin glucoside from Phyllanthus emblica L.

    PubMed

    El-Desouky, S K; Ryu, Shi Young; Kim, Young-Kyoon

    2008-01-10

    A new acylated apigenin glucoside (apigenin-7-O-(6''-butyryl-beta-glucopyranoside) (1) was isolated from the methanolic extract of the leaves of Phyllanthus emblica L. (Euphorbiaceae) together with the known compounds; gallic acid (2), methyl gallate (3), 1,2,3,4,6-penta-O-galloylglucose (4) and luteolin-4'-O-neohesperiodoside (5). Their chemical structures were elucidated on the basis of spectroscopic studies ((1)H NMR, (13)C NMR, DEPT, HSQC, HMBC).

  11. A new 5-alkylresorcinol glucoside derivative from Cybianthus magnus.

    PubMed

    Cabanillas, B; Vásquez-Ocmín, P; Zebiri, I; Rengifo, E; Sauvain, M; Le, H L; Vaisberg, A; Voutquenne-Nazabadioko, L; Haddad, M

    2016-01-01

    One new 5-alkylresorcinol glucoside (1) was isolated from leaves of Cybianthus magnus, along with 12 known compounds (2-13), isolated from four plants belonging to Myrsinaceae family. Their structures were determined on the basis of spectroscopic analysis and by comparison of their spectral data with those reported in the literature. Among the tested molecules, only compound 2 displayed a strong cytotoxic activity with IC50 values ranging between 22 and 100 μM for all cell lines tested. One new 5-alkylresorcinol glucoside (1) was isolated from leaves of Cybianthus magnus, along with 12 known compounds, isolated from four plants belonging to Myrsinaceae family (2, 3 isolated from C. magnus; 4-7, 10 and 11 isolated from Myrsine latifolia; 4, 8 and 9 isolated from Myrsine sessiflora; 6, 7, 10, 12 and 13 isolated from Myrsine congesta). Their structures were determined on the basis of spectroscopic analysis and by comparison of their spectral data with those reported in the literature. So far, only nine 5-alkylresorcinol glucosides were isolated from leaves of Grevillea robusta. Since resorcinols are known to exhibit strong cytotoxic activity, compounds 1 and 2 were tested against cell lines 3T3, H460, DU145 and MCF-7 for cytotoxicity in vitro and compounds 3-13 were tested for their antileishmanial activity. Compound 2 displayed a strong cytotoxic activity with IC50 values ranging between 22 and 100 μM for all tested cell lines. Compounds 3-13 were not active against Leishmania amazonensis amastigotes.

  12. Enzymatic Biosynthesis of Novel Resveratrol Glucoside and Glycoside Derivatives

    PubMed Central

    Pandey, Ramesh Prasad; Parajuli, Prakash; Shin, Ju Yong; Lee, Jisun; Lee, Seul; Hong, Young-Soo; Park, Yong Il; Kim, Joong Su

    2014-01-01

    A UDP glucosyltransferase from Bacillus licheniformis was overexpressed, purified, and incubated with nucleotide diphosphate (NDP) d- and l-sugars to produce glucose, galactose, 2-deoxyglucose, viosamine, rhamnose, and fucose sugar-conjugated resveratrol glycosides. Significantly higher (90%) bioconversion of resveratrol was achieved with α-d-glucose as the sugar donor to produce four different glucosides of resveratrol: resveratrol 3-O-β-d-glucoside, resveratrol 4′-O-β-d-glucoside, resveratrol 3,5-O-β-d-diglucoside, and resveratrol 3,5,4′-O-β-d-triglucoside. The conversion rates and numbers of products formed were found to vary with the other NDP sugar donors. Resveratrol 3-O-β-d-2-deoxyglucoside and resveratrol 3,5-O-β-d-di-2-deoxyglucoside were found to be produced using TDP-2-deoxyglucose as a donor; however, the monoglycosides resveratrol 4′-O-β-d-galactoside, resveratrol 4′-O-β-d-viosaminoside, resveratrol 3-O-β-l-rhamnoside, and resveratrol 3-O-β-l-fucoside were produced from the respective sugar donors. Altogether, 10 diverse glycoside derivatives of the medically important resveratrol were generated, demonstrating the capacity of YjiC to produce structurally diverse resveratrol glycosides. PMID:25239890

  13. Structural revision of some recently published iridoid glucosides.

    PubMed

    Jensen, Søren R; Caliş, Ihsan; Gotfredsen, Charlotte H; Søtofte, Inger

    2007-01-01

    The structures of six different iridoid glucosides have been revised. Three compounds isolated from Eremostachys glabra and designated 6,9-epi-8-O-acetylshanziside (1), 5,9-epi-penstemoside (2), and 5,9-epi-7,8-didehydropenstemoside (3) have been shown to be identical to the known iridoids barlerin (4, 8-O-acetylshanziside), penstemoside (5), and 7,8-didehydropenstemoside (6), respectively. Another compound named harpagoside-B, isolated from Scrophularia deserti and proposed to be 9-epi-6-O-methylharpagoside (11), was demonstrated from the spectroscopic data given to be the known harpagoside (10b). Finally, two alleged iridoid galactosides from Buddleja crispa named buddlejosides A and B (12a and 12b) have been shown to be the corresponding glucosides; the former is identical to agnuside (13a), while the latter is 3,4-dihydroxybenzoylaucubin (13b), an iridoid glucoside not previously published. This clearly showed that care should be taken with the interpretation of NOEs involving bridgehead protons in iridoid structures because they can be capricious and lead to erroneous structural assignments.

  14. Dynamical dimer-dimer correlation functions from exact diagonalization

    SciTech Connect

    Werner, Ralph

    2001-05-01

    A regularization method is presented to deduce dynamic correlation functions from exact diagonalization calculations. It is applied to dimer-dimer correlation functions in quantum spin chains relevant for the description of spin-Peierls systems. Exact results for the XY model are presented. The analysis draws into doubt that the dimer-dimer correlation functions show the same scale invariance as spin-spin correlation functions. The results are applied to describe the quasielastic scattering in CuGeO{sub 3} and the hardening of the Peierls-active phonons.

  15. Dianthosaponins A-F, triterpene saponins, flavonoid glycoside, aromatic amide glucoside and γ-pyrone glucoside from Dianthus japonicus.

    PubMed

    Nakano, Takahiro; Sugimoto, Sachiko; Matsunami, Katsuyoshi; Otsuka, Hideaki

    2011-01-01

    From aerial parts of Dianthus japonicus, six new and seven known oleanane-type triterpene saponins were isolated. The structures of the new saponins, named dianthosaponins A-F, were elucidated by means of high resolution mass spectrometry, and extensive inspection of one- and two-dimensional NMR spectroscopic data. A new C-glycosyl flavone, a glycosidic derivative of anthranilic acid amide and a maltol glucoside were also isolated.

  16. The acrylonitrile dimer ion

    NASA Astrophysics Data System (ADS)

    Ervasti, Henri K.; Jobst, Karl J.; Burgers, Peter C.; Ruttink, Paul J. Ae; Terlouw, Johan K.

    2007-04-01

    Large energy barriers prohibit the rearrangement of solitary acrylonitrile ions, CH2CHCN+, into their more stable hydrogen-shift isomers CH2CCNH+ or CHCH-CNH+. This prompted us to examine if these isomerizations occur by self-catalysis in acrylonitrile dimer ions. Such ions, generated by chemical ionization experiments of acrylonitrile with an excess of carbon dioxide, undergo five dissociations in the [mu]s time frame, as witnessed by peaks at m/z 53, 54, 79, 80 and 105 in their metastable ion mass spectrum. Collision experiments on these product ions, deuterium labeling, and a detailed computational analysis using the CBS-QB3 model chemistry lead to the following conclusions: (i) the m/z 54 ions are ions CH2CHCNH+ generated by self-protonation in ion-dipole stabilized hydrogen-bridged dimer ions [CH2CHCN...H-C(CN)CH2]+ and [CH2CHCN...H-C(H)C(H)CN]+; the proton shifts in these ions are associated with a small reverse barrier; (ii) dissociation of the H-bridged ions into CH2CCNH+ or CHCH-CNH+ by self-catalysis is energetically feasible but kinetically improbable: experiment shows that the m/z 53 ions are CH2CHCN+ ions, generated by back dissociation; (iii) the peaks at m/z 79, 80 and 105 correspond with the losses of HCN, C2H2 and H, respectively. The calculations indicate that these ions are generated from dimer ions that have adopted the (much more stable) covalently bound "head-to-tail" structure [CH2CHCN-C(H2)C(H)CN]+; experiments indicate that the m/z 79 (C5H5N) and m/z 105 (C6H6N2) ions have linear structures but the m/z 80 (C4H4N2) ions consist of ionized pyrimidine in admixture with its stable pyrimidine-2-ylidene isomer. Acrylonitrile is a confirmed species in interstellar space and our study provides experimental and computational evidence that its dimer radical cation yields the ionized prebiotic pyrimidine molecule.

  17. D Dimer in acute care

    PubMed Central

    Sathe, Prachee M.; Patwa, Urvil D.

    2014-01-01

    Pulmonary embolism, Deep Vein Thrombosis (DVT) and Disseminated intravascular coagulation (DIC) are important sources of mortality and morbidity in intensive care unit (ICU). And every time D-dimer remains the the commonest investigation. Many times D-dimer is erroneously considered as a diagnostic test in above mentioned conditions. Its interpretation requires cautions. To circumvent this source of error it is necessary to understand D-dimer test and its significance in various disorder. This article review some basic details of D-dimer, condition associated with its increased level and some prognostic value in intracranial hemorrhage and gastrointestinal (GI) bleed. PMID:25337485

  18. Plasma-induced dimerization of phloridzin as a new class of anti-adipogenic agents.

    PubMed

    Jeong, Gyeong Han; Cho, Jae-Hyeon; Kim, Seong-Ho; Kim, Tae Hoon

    2017-09-18

    Phloridzin is a natural phloretin glucoside found in several parts of apple trees and is an attractive target for structural modification as novel pharmaceutical agent. Nonthermal dielectric barrier discharge (DBD) plasma-induced structural changes in dihydrochalcone phloridzin (1) resulted in the isolation of three new methylene-bridged dihydrochalcone dimers, methylenebisphloridzin (2), deglucosylmethylenebisphloridzin (3), and methylenebisphloretin (4), along with phloretin (5). The chemical structures of these newly generated compounds were elucidated by interpretation of their spectroscopic data. The new phloretin dimer 4 connected by a methylene linkage exhibited significantly improved anti-adipogenic properties against pancreatic lipase as well as differentiation of 3T3-L1 preadipocytes compared to the parent compound phloridzin. Copyright © 2017. Published by Elsevier Ltd.

  19. A new 2-alkylhydroquinone glucoside from Phagnalon saxatile (L.) Cass.

    PubMed

    Cherchar, Hanene; Lehbili, Meriem; Berrehal, Djemaa; Morjani, Hamid; Alabdul Magid, Abdulmagid; Voutquenne-Nazabadioko, Laurence; Kabouche, Ahmed; Kabouche, Zahia

    2017-09-25

    A new 2-alkylhydroquinone glucoside, 1-O-β-d-glucopyranosyl-1,4-dihydroxy-2-((E) 2-oxo-3-butenyl)benzene (1), in addition to nine known compounds were isolated from the aerial parts of Phagnalon saxatile (L.) Cass. (Asteraceae). Their structures were identified based on spectroscopic methods including 1D and 2D NMR, mass spectrometry (HR-ESI-MS), UV spectral analyses and by comparison with literature data. The cytotoxic activity of three isolated compounds (1-3) was evaluated against fibrosarcoma (HT1080), human lung cancer (A549) and breast cancer (MCF7) cell lines.

  20. Iridoid glucosides with insecticidal activity from Galium melanantherum.

    PubMed

    Tzakou, Olga; Mylonas, Philippos; Vagias, Constantinos; Petrakis, Panos V

    2007-01-01

    The insecticidal activity of the endemic species Galium melanantherum was evaluated against Crematogaster scutellaris ants and Kalotermes flavicollis termites. Iridoid glucosides 1-7 were isolated for the first time as metabolites of the investigated plant, along with the coumarin scopolin. The main components of the extract were found to be the non-acetylated iridoids: geniposidic acid (1), 10-hydroxyloganin (2), deacetyldaphylloside (3), monotropein (4), deacetylasperulosidic acid (5) and scandoside (6), while asperulosidic acid (7) was present only in minute quantities. All isolated metabolites were identified on the basis of their spectral data. Laboratory bioassays revealed significant levels of toxicity for 1-4 against Kalotermes flavicollis termites and Crematogaster scutellaris ants.

  1. An Iridoid Glucoside and the Related Aglycones from Cornus florida

    PubMed Central

    2015-01-01

    A new iridoid glucoside, cornusoside A (1), and four new natural product iridoid aglycones, cornolactones A–D (2–5), together with 10 known compounds were isolated from the leaves of Cornus florida. The structures of compounds 1–5 were established by interpretation of their spectroscopic data. Cornolactone B (3) is the first natural cis-fused tricyclic dilactone iridoid containing both a five- and a six-membered lactone ring. A biosynthesis pathway is proposed for cornolactones C (4) and D (5), the C-6 epimers of compounds 1–3. PMID:25141901

  2. Nitrile glucosides and serotobenine from Campylospermum glaucum and Ouratea turnarea.

    PubMed

    Abouem à Zintchem, Auguste; Bikobo, Dominique Ngono; de Théodore Atchadé, Alex; Mbing, Joséphine Ngo; Gangoue-Pieboji, Joseph; Tih, Raphael Ghogomu; Blond, Alain; Pegnyemb, Dieudonné Emmanuel; Bodo, Bernard

    2008-08-01

    Two nitrile glucosides (1S,3S,4S,5R)-4-benzoyloxy-2-cyanomethylene-3,5-dihydroxycyclohexyl-1-O-beta-glucopyranoside (campyloside A) and (1S,3S,4S,5R)-5-benzoyloxy-2-cyanomethylene-3-hydroxy-4-(2-pyrrolcarboxyloxy)cyclohexyl-1-O-beta-glucopyranoside (campyloside B) were isolated from the stem roots of Campylospermum glaucum, whereas serotobenine was isolated from Ouratea turnarea. The structure elucidations were based on spectroscopic evidence. The biological assays of compounds and crude extract of plant species showed good antimicrobial activity of crude extracts against Gram-positive cocci.

  3. A labdane diterpene glucoside from the rhizomes of Curcuma mangga.

    PubMed

    Abas, Faridah; Lajis, Nordin H; Shaari, Khozirah; Israf, Daud Ahmad; Stanslas, Johnson; Yusuf, Umi Kalsom; Raof, Salahuddin Mohd

    2005-07-01

    A new labdane diterpene glucoside, curcumanggoside (1), together with nine known compounds, including labda-8(17),12-diene-15,16-dial (2), calcaratarin A (3), zerumin B (4), scopoletin, demethoxycurcumin, bisdemethoxycurcumin, 1,7-bis(4-hydroxyphenyl)-1,4,6-heptatrien-3-one, curcumin, and p-hydroxycinnamic acid, have been isolated from the rhizomes of Curcuma mangga. Their structures were determined using a combination of 1D (1H NMR, 13C NMR, DEPT) and 2D (COSY, HSQC, HMBC) NMR techniques. All diarylheptanoids and scopoletin showed significant antioxidant activity. Zerumin B, demethoxycurcumin, bisdemethoxycurcumin, and curcumin also exhibited cytotoxic activity against a panel of five human tumor cell lines.

  4. Andrographidine G, a new flavone glucoside from Andrographis paniculata.

    PubMed

    Hapuarachchi, Swarna D; Ali, Zulfiqar; Abe, Naohito; Sugandhika, Suresh T; Sandun, Senerath T P; Khan, Ikhlas A

    2013-03-01

    A new flavone glucoside, andrographidine G (1), was isolated from Andrographis paniculata together with 13 known compounds, including flavonoids, diterpenoids, and iridoids. The structure of 1 was established by spectroscopic and spectrometric techniques, including HR-ESI-TOF-MS, 1D and 2D NMR, and chemical methods. The known compounds were identified as andrographidine A (2), (2R)-5-hydroxy-7,8-dimethoxyflavanone-5-O-beta-D-glucopyranoside (3), acanthoside B (4), neoandrographiside (5), andropanoside (6), andrographiside (7), andrographolide (8), 14-deoxy-11,12-didehydroandrographiside (9), 14-deoxy-11,12-didehydroandrographolide (10), procumbide (11), procumboside (12), 6-epi-8-O-acetylharpagide (13), and curvifloruside F (14).

  5. Final report on the amended safety assessment of diisopropyl dimer dilinoleate, dicetearyl dimer dilinoleate, diisostearyl dimer dilinoleate, dioctyl dimer dilinoleate, dioctyldodecyl dimer dilinoleate, and ditridecyl dimer dilinoleate.

    PubMed

    Fiume, Monice Zondlo

    2003-01-01

    Diisopropyl Dimer Dilinoleate, Dicetearyl Dimer Dilinoleate, Diisostearyl Dimer Dilinoleate, Dioctyl Dimer Dilinoleate, Dioctyldodecyl Dimer Dilinoleate, and Ditridecyl Dimer Dilinoleate are diesters of their respective alcohols and dilinoleic acid. They function as skin-conditioning agents in a variety of cosmetic products at concentrations around 10%, but may be used at concentrations up to 53% in lipsticks. These ingredients do not absorb radiation in the ultraviolet (UV) UVA or UVB range and the only impurities expected are <0.5% dilinoleic acid, <0.1% isopropyl alcohol or <1% isostearyl alcohol, and/or small amounts of dilinoleic acid and cetearyl alcohol or octyldodecanol, depending on which diester is used. The potential skin penetration of these ingredients was evaluated using an estimate of the octanol/water partition coefficient (logP of 17.7) based on the structure of Diisopropyl Dimer Dilinoleate. This is consistent with the insolubility of these ingredients in water. Safety test data on dilinoleic acid (no adverse effects) were considered relevant because dilinoleic acid is a component of these diesters and a likely breakdown product. The acute oral and dermal LD(50) values for rats of Diisopropyl, Diisostearyl, and Dioctyldodecyl Dimer Dilinoleate were >5.0 g/kg. In a subchronic feeding study, macrophage aggregation was seen in the mesenteric lymph node at the lowest dose level (0.1% in the diet). These ingredients did not produce skin or ocular irritation in animal tests, nor were they comedogenic. Ames testing, clastogenesis in human lymphocytes in culture, and L5178Y mouse lymphoma cell forward mutations were all negative, indicating no dilinoleic acid genotoxicity. No carcinogenicity or reproductive/developmental toxicity data were available; however, structural alerts that would suggest a mutagenic or carcinogenic risk are absent. Significant reproductive/developmental toxicity or other systemic toxicity is not expected with these ingredients

  6. Anomericity of T-2 Toxin-glucoside: Masked Mycotoxin in Cereal Crops

    PubMed Central

    2015-01-01

    T-2 toxin is a trichothecene mycotoxin produced when Fusarium fungi infect grains, especially oats and wheat. Ingestion of T-2 toxin contaminated grain can cause diarrhea, hemorrhaging, and feed refusal in livestock. Cereal crops infected with mycotoxin-producing fungi form toxin glycosides, sometimes called masked mycotoxins, which are a potential food safety concern because they are not detectable by standard approaches and may be converted back to the parent toxin during digestion or food processing. The work reported here addresses four aspects of T-2 toxin-glucosides: phytotoxicity, stability after ingestion, antibody detection, and the anomericity of the naturally occurring T-2 toxin-glucoside found in cereal plants. T-2 toxin-β-glucoside was chemically synthesized and compared to T-2 toxin-α-glucoside prepared with Blastobotrys muscicola cultures and the T-2 toxin-glucoside found in naturally contaminated oats and wheat. The anomeric forms were separated chromatographically and differ in both NMR and mass spectrometry. Both anomers were significantly degraded to T-2 toxin and HT-2 toxin under conditions that mimic human digestion, but with different kinetics and metabolic end products. The naturally occurring T-2 toxin-glucoside from plants was found to be identical to T-2 toxin-α-glucoside prepared with B. muscicola. An antibody test for the detection of T-2 toxin was not effective for the detection of T-2 toxin-α-glucoside. This anomer was produced in sufficient quantity to assess its animal toxicity. PMID:25520274

  7. Citrus limonin glucoside supplementation decreased biomarkers of liver disease in overweight human subjects

    USDA-ARS?s Scientific Manuscript database

    Orange juice and mixtures of citrus limonoid glucosides isolated from orange juice or its byproducts demonstrated health benefits in human and animal studies. However, the risks and benefits of purified limonin glucoside (LG) in humans are unknown. Aim of this study was to determine the safety and m...

  8. Anomericity of T-2 toxin-glucoside: masked mycotoxin in cereal crops.

    PubMed

    McCormick, Susan P; Kato, Takayuki; Maragos, Chris M; Busman, Mark; Lattanzio, Veronica M T; Galaverna, Gianni; Dall-Asta, Chiara; Crich, David; Price, Neil P J; Kurtzman, Cletus P

    2015-01-21

    T-2 toxin is a trichothecene mycotoxin produced when Fusarium fungi infect grains, especially oats and wheat. Ingestion of T-2 toxin contaminated grain can cause diarrhea, hemorrhaging, and feed refusal in livestock. Cereal crops infected with mycotoxin-producing fungi form toxin glycosides, sometimes called masked mycotoxins, which are a potential food safety concern because they are not detectable by standard approaches and may be converted back to the parent toxin during digestion or food processing. The work reported here addresses four aspects of T-2 toxin-glucosides: phytotoxicity, stability after ingestion, antibody detection, and the anomericity of the naturally occurring T-2 toxin-glucoside found in cereal plants. T-2 toxin-β-glucoside was chemically synthesized and compared to T-2 toxin-α-glucoside prepared with Blastobotrys muscicola cultures and the T-2 toxin-glucoside found in naturally contaminated oats and wheat. The anomeric forms were separated chromatographically and differ in both NMR and mass spectrometry. Both anomers were significantly degraded to T-2 toxin and HT-2 toxin under conditions that mimic human digestion, but with different kinetics and metabolic end products. The naturally occurring T-2 toxin-glucoside from plants was found to be identical to T-2 toxin-α-glucoside prepared with B. muscicola. An antibody test for the detection of T-2 toxin was not effective for the detection of T-2 toxin-α-glucoside. This anomer was produced in sufficient quantity to assess its animal toxicity.

  9. Chromone and chromanone glucosides from Hypericum sikokumontanum and their anti-Helicobacter pylori activities.

    PubMed

    Tanaka, Naonobu; Kashiwada, Yoshiki; Nakano, Tatsuro; Shibata, Hirofumi; Higuchi, Tomihiko; Sekiya, Michiko; Ikeshiro, Yasumasa; Takaishi, Yoshihisa

    2009-01-01

    Chromone glucosides, takanechromones A-C (1, 2 and 5) and chromanone glucosides, named takanechromanones A and B (3 and 4), were isolated from the methanolic extracts of Hypericumsikokumontanum together with 27 known compounds. Their structures were established based on spectroscopic evidence. The isolated compounds and some chromone derivatives were assayed for antimicrobial activity against Helicobacter pylori and cytotoxicity against human cancer cell lines.

  10. Glucosides from MBOA and BOA detoxification by Zea mays and Portulaca oleracea.

    PubMed

    Hofmann, Diana; Knop, Mona; Hao, Huang; Hennig, Lothar; Sicker, Dieter; Schulz, Margot

    2006-01-01

    Incubation of Zea mays cv. Nicco seedlings with 6-methoxybenzoxazolin-2(3H)-one (MBOA) led to a minor detoxification product hitherto only found in Poaceae. This new compound was identified as 1-(2-hydroxy-4-methoxyphenylamino)-1-deoxy-beta-glucoside 1,2-carbamate (1) (methoxy glucoside carbamate) and represents an analogue to the previously described 1-(2-hydroxyphenylamino)-1-deoxy-beta-glucoside 1,2-carbamate (glucoside carbamate) from benzoxazolin-2(3H)-one (BOA). In Portulaca oleracea var. sativa cv. Gelber treatment with BOA resulted in further unknown detoxification products, which were not synthesized in detectable amounts after BOA absorption in all other species tested. Compound 1 easily undergoes decay into BOA-5-O-glucoside (2). Z. mays seedlings, known to produce BOA-6-O-Glc on incubation with BOA, are able to transform BOA-5-OH into BOA-5-O-glucoside (2). Besides the known compounds, maize contained a formerly unseen product that accumulated during late stages of the detoxification process. It was isolated and identified as 1-(2-hydroxyphenylamino)-6-O-malonyl-1-deoxy-beta-glucoside 1,2-carbamate (3) (malonyl glucoside carbamate).

  11. Water-soluble constituents of caraway: carvone derivatives and their glucosides.

    PubMed

    Matsumura, Tetsuko; Ishikawa, Toru; Kitajima, Junichi

    2002-01-01

    Nine monoterpenoids related to carvone and seven glucosides were isolated from the water-soluble portion of the methanolic extract of the caraway (fruit of Carum carvi L.), and their structures were clarified by spectral investigation. Among them, eight monoterpenoids and six glucosides were new.

  12. [Study on the coumarin glucosides of Angelica dahurica].

    PubMed

    Sun, Hao; Zhao, Xing-Zeng; Jia, Xiao-Dong; Wang, Xiang-Yun; Dong, Yun-Fa; Feng, Xu

    2012-11-01

    To study the coumarin glucosides of Angelica dahurica. Fresh roots and rhizomes of Angelica dahurica were extracted with ethanol at room temperature. Repeated column chromatography and preparative HPLC were used to isolate and purify the compounds. Their structures were elucidated on the basis of chemical evidence and spectral analysis. Twenty-six coumarin glucosides were isolated from Angelica dahurica, while here we reported 7 of them: sec.-O-beta-D-Galactopyranosyl-(R)-byakangelicin (I);8-O-beta-D-Galactopyranosyl-xanthotoxol (II); 7-O-beta-D-Apiofuranosyl-(1-->6)-beta-D-Glucopyranosyl-peucedanol (III); (R)-peucedanol-7-O-beta-D-Glucopyranoside (IV); sec.-O-beta-D-Glucopyranosyl-(R)-Oxypeucedaninhydrate (V); 7-O-beta-D-Galactopyranosyl-Sco-poletin( VI); Aesculin (VII). Compound V is a new compound, Compound VII is isolated from Umbellifera for the first time, compounds III, IV are isolated from Angelica for the first time,while compound I, II and VI are isolated from this plant for the first time.

  13. Isolation of Some Glucosides as Aroma Precursors from Ginger.

    PubMed

    Sekiwa, Y; Mizuno, Y; Yamamoto, Y; Kubota, K; Kobayashi, A; Koshino, H

    1999-01-01

    A glycosidically bound fraction was prepared by adsorbing a 80% methanol extract from fresh rhizomes of ginger onto a column of Amberlite XAD-2 resin and successively eluting with ethyl acetate or methanol. Enzymatic hydrolysis of this fraction with an acetone powder prepared from fresh ginger and commercial glycosidase liberated such alcohols as geraniol, 2-heptanol, α-terpineol, nerol, linalool, and citronellol, suggesting that fresh ginger included glycosides and glycosidase. The ethyl acetate eluate was chromatographed by an ODS flash column and then HPLC to isolate the β-glucopyranosides of 5-hydroxyborneol, 1,8-epoxy-p-menthan-3-ol, (2E, 6E)- and (2E, 6Z)-3,7-dimethyl-8-hydroxyoctadien-1-ol, 2-heptanol, geraniol, nerol, (R)-linalool, and citronellol. All the glucosides, except for 5-hydroxybornyl-O-β-D-glucopyranoside, were identified for the first time in the rhizome of ginger, and many of their aglycons were major constituents of the essential oil. The results indicate that these glucosides are aroma precursors of fresh ginger.

  14. Stochastic analysis of dimerization systems.

    PubMed

    Barzel, Baruch; Biham, Ofer

    2009-09-01

    The process of dimerization, in which two monomers bind to each other and form a dimer, is common in nature. This process can be modeled using rate equations, from which the average copy numbers of the reacting monomers and of the product dimers can then be obtained. However, the rate equations apply only when these copy numbers are large. In the limit of small copy numbers the system becomes dominated by fluctuations, which are not accounted for by the rate equations. In this limit one must use stochastic methods such as direct integration of the master equation or Monte Carlo simulations. These methods are computationally intensive and rarely succumb to analytical solutions. Here we use the recently introduced moment equations which provide a highly simplified stochastic treatment of the dimerization process. Using this approach, we obtain an analytical solution for the copy numbers and reaction rates both under steady-state conditions and in the time-dependent case. We analyze three different dimerization processes: dimerization without dissociation, dimerization with dissociation, and heterodimer formation. To validate the results we compare them with the results obtained from the master equation in the stochastic limit and with those obtained from the rate equations in the deterministic limit. Potential applications of the results in different physical contexts are discussed.

  15. Enzymatic Synthesis of Apigenin Glucosides by Glucosyltransferase (YjiC) from Bacillus licheniformis DSM 13

    PubMed Central

    Gurung, Rit Bahadur; Kim, Eun-Hee; Oh, Tae-Jin; Sohng, Jae Kyung

    2013-01-01

    Apigenin, a member of the flavone subclass of flavonoids, has long been considered to have various biological activities. Its glucosides, in particular, have been reported to have higher water solubility, increased chemical stability, and enhanced biological activities. Here, the synthesis of apigenin glucosides by the in vitro glucosylation reaction was successfully performed using a UDP-glucosyltransferase YjiC, from Bacillus licheniformis DSM 13. The glucosylation has been confirmed at the phenolic groups of C-4′ and C-7 positions ensuing apigenin 4′-O-glucoside, apigenin 7-O-glucoside and apigenin 4′,7-O-diglucoside as the products leaving the C-5 position unglucosylated. The position of glucosylation and the chemical structures of glucosides were elucidated by liquid chromatography/mass spectroscopy and nuclear magnetic resonance spectroscopy. The parameters such as pH, UDP glucose concentration and time of incubation were also analyzed during this study. PMID:24170092

  16. Amaranthin in feather cockscombs is synthesized via glucuronylation at the cyclo-DOPA glucoside step in the betacyanin biosynthetic pathway.

    PubMed

    Sasaki, Nobuhiro; Abe, Yutaka; Wada, Katsuhiro; Koda, Takatoshi; Goda, Yukihiro; Adachi, Taiji; Ozeki, Yoshihiro

    2005-12-01

    Uridine 5'-diphosphate (UDP)-glucuronic acid: cyclo-DOPA 5-glucoside glucuronosyltransferase activity was detected in a crude extract prepared from the purple flowers of feather cockscombs. This suggests that the glucuronic acid moiety of amaranthin and its derivatives may be introduced at the cyclo-DOPA glucoside step, but not at the betanidin glucoside step.

  17. Phenanthrenes, 9,10-dihydrophenanthrenes, bibenzyls with their derivatives, and malate or tartrate benzyl ester glucosides from tubers of Cremastra appendiculata.

    PubMed

    Wang, Yang; Guan, Shu-Hong; Meng, Yu-Hui; Zhang, Yi-Bei; Cheng, Chun-Ru; Shi, Yang-Yang; Feng, Rui-Hong; Zeng, Feng; Wu, Zhi-Yuan; Zhang, Jing-Xian; Yang, Min; Liu, Xuan; Li, Qing; Chen, Xiao-Hui; Bi, Kai-Shun; Guo, De-An

    2013-10-01

    Eleven previously unknown compounds and 23 known compounds, including 20 phenanthrene or 9,10-dihydrophenanthrene derivatives, five bibenzyls, seven malate or tartrate benzyl ester glucosides, adenosine and gastrodin were isolated from tubers of Cremastra appendiculata. Among the obtained compounds, two are the first isolated dimers with one phenanthrene or bibenzyl unit connected to C-3 of 2,3,4,5-tetrahydro-phenanthro[2,1-b]furan moiety. In addition, 33 of these compounds were evaluated in vitro for their cytotoxic activity against two cancer cell lines. Among the compounds examined, one compound showed moderate cytotoxic activity, while five showed weak cytotoxic activity against the A549 cell line. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Officinalioside, a new lignan glucoside from Borago officinalis L.

    PubMed

    Samy, Mamdouh Nabil; Hamed, Ashraf Nageeb El-Sayed; Sugimoto, Sachiko; Otsuka, Hideaki; Kamel, Mohamed Salah; Matsunami, Katsuyoshi

    2016-01-01

    A new lignan glucoside, officinalioside (1), was isolated from n-BuOH fraction of the aerial parts of Borago officinalis L., together with four known compounds: actinidioionoside (2), roseoside (3), crotalionoside C (4) and kaempferol 3-O-β-D-galactopyranoside (5). The structure of the new compound was established by means of spectroscopic and chemical analyses. Compounds 1 and 2 showed a moderate DPPH radical scavenging activity (IC50: 52.6 ± 1.70 and 41.3 ± 0.25 μM, respectively) comparable with that of the standard trolox (16.6 ± 2.2 μM) without any significant cytotoxicity towards human cell line A549 (IC50 > 100 μM).

  19. Preparation and swelling inhibition of cation glucoside to montmorillonite

    NASA Astrophysics Data System (ADS)

    Song, Shaofu; Liu, Jurong; Guo, Gang; Huang, Lei; Qu, Chentun; Li, Bianqin; Chen, Gang

    2017-06-01

    In this work, a cation glucoside (CG) was synthesized with glucose and glycidyl trimethyl ammonium chloride (GTA) and used as montmorillonite (MMT) swelling inhibiter. The inhibition of CG was investigated by MMT linear expansion test and mud ball immersing test. The results showed that the CG has a good inhibition to the hydration swelling and dispersion of MMT. Under the same condition, the linear expansion rate of MMT in CG solution is much lower that of methylglucoside and the hydration expansion degree of the mud ball in the CG solution was significantly inhibited. The characterizations of physic-chemical properties of particle, analysized by thermogravimetric analysis and scanning electron microscopy, revealed that CG play great role to prevent water from absorb and keep MMT in large particle size.

  20. Acylated cyanidin 3-sambubioside-5-glucosides in Matthiola incana.

    PubMed

    Saito, N; Tatsuzawa, F; Nishiyama, A; Yokoi, M; Shigihara, A; Honda, T

    1995-03-01

    Four acylated cyanidin 3-sambubioside-5-glucosides were isolated from purple-violet flowers of Matthiola incana and their structures were determined by chemical and spectroscopic methods. Three acylated anthocyanins were cyanidin 3-O-(6-O-acyl-2-O-(2-O-sinapyl-beta-D-xylopyranosyl)-beta-D- glucopyranosides)-5-O-(6-O-malonyl-beta-D-glucopyranosides), in which the acyl group is p-coumaryl, caffeyl or ferulyl, respectively. The remaining pigment is free from malonic acid and was identified as cyanidin 3-O-(6-O-trans-ferulyl-2-O-(2- O-trans-sinapyl-beta-D-xylopyranosyl)-beta-D-glucopyranoside)-5-O- (beta-D-glucopyranoside). Analysis of the anthocyanin constituents in 16 purple-violet cultivars revealed that they contained the above triacylated anthocyanins in variable amounts as main pigments. An aromatic pair of pigments containing sinapic and ferulic acids are considered to produce an important intramolecular effect, making bluish colours in these flowers.

  1. Four new neolignan glucosides from the fruits of Arctium lappa.

    PubMed

    Huang, Xiao-Ying; Feng, Zi-Ming; Yang, Ya-Nan; Jiang, Jian-Shuang; Zhang, Pei-Cheng

    2015-05-01

    Four new neolignan glucosides named (7S, 8R)-4,7,9,9'-tetrahydroxy-3,3'-dimethoxy-8-O-4'-neolignan-9'-O-β-d-apiofuranosyl-(1 → 6)-O-β-d-glucopyranoside (1), (8R)-4,9,9'-trihydroxy-3,3'-dimethoxy-7-oxo-8-O-4'-neolignan-4-O-β-d-glucopyranoside (2), (7R, 8S)-dihydrodehydrodiconiferyl alcohol-7'-oxo-4-O-β-d-glucopyranoside (3), and (7'S, 8'R, 8S)-4,4',9'-trihydroxy-3,3'-dimethoxy-7',9-epoxylignan-7-oxo-4-O-β-d-glucopyranoside (4) were isolated from the fruits of Arctium lappa L. Their structures and absolute configurations were elucidated on the basis of comprehensive spectroscopic analyses (UV, IR, HR-ESI-MS, 1D and 2D NMR, CD), as well as by comparison with known analogues in the literature.

  2. DNA damage protection against free radicals of two antioxidant neolignan glucosides from sugarcane molasses.

    PubMed

    Asikin, Yonathan; Takahashi, Makoto; Mizu, Masami; Takara, Kensaku; Oku, Hirosuke; Wada, Koji

    2016-03-15

    Sugarcane molasses is a potential by-product of the sugarcane manufacturing industry that is rich in antioxidant materials. The present study aimed to obtain antioxidative compounds from sugarcane molasses and to evaluate their ability to protect DNA from oxidative damage. Two neolignan glucosides were isolated from sugarcane molasses using bioassay and UV spectra monitoring-guided fractionation. The compounds were elucidated as (7R,8S)-dehydrodiconiferyl alcohol-4-O-β-d-glucoside (1) and (7S,8R)-simulanol-9'-O-β-d-glucoside (2). Neolignan glucoside 2 protected against DNA damage caused by free radicals more effectively than did neolignan glucoside 1 (13.62 and 9.08 µmol L(-1) for peroxyl and hydroxyl radicals, respectively, compared to 48.07 and 14.42 µmol L(-1) ). Additionally, neolignan glucoside 2 exhibited superior DNA protection against free radicals compared with various known antioxidative compounds, including p-coumaric acid, ferulic acid, vanillic acid and epigallocatechin gallate. The isolated neolignan glucosides from sugarcane molasses are able to protect DNA from oxidative damage caused by free radicals. This is the first identification of these two compounds in sugarcane molasses. The sugarcane molasses can therefore be used as potential nutraceutical preventative agents, and the findings may foster the utilization of this by-product as a bioresource-based product. © 2015 Society of Chemical Industry. Copyright © 2015 Society of Chemical Industry.

  3. Naphthalene glucoside and other phenolics from the shoot and callus cultures of Drosophyllum lusitanicum.

    PubMed

    Budzianowski, Jaromir; Budzianowska, Anna; Kromer, Krystyna

    2002-10-01

    The callus and, for the first time established, shoot cultures of Drosophyllum lusitanicum Link. (Droseraceae) yielded new naphthalene glucoside-5-hydroxy-4-methoxy-2-naphthalenecarboxylic acid 5-O-beta-glucoside (drosophylloside) and 5-hydroxy-4-methoxy-2-naphthalenecarboxylic acid methyl ester besides other phenolics like naphthalenes-5-hydroxy-4-methoxy-2-naphthalenecarboxylic acid (ancistronaphthoic acid B), hydroplumbagin 4-O-glucoside, naphthoquinones-plumbagin and 3-chloroplumbagin, C-glycosylflavones- vitexin, isovitexin, orientin and isoorientin. The pattern of phenolics found supports affinity of Drosophyllum to the families-Droseraceae, Ancistrocladaceae and Dioncophyllaceae.

  4. Mechanism and evolution of protein dimerization.

    PubMed Central

    Xu, D.; Tsai, C. J.; Nussinov, R.

    1998-01-01

    We have investigated the mechanism and the evolutionary pathway of protein dimerization through analysis of experimental structures of dimers. We propose that the evolution of dimers may have multiple pathways, including (1) formation of a functional dimer directly without going through an ancestor monomer, (2) formation of a stable monomer as an intermediate followed by mutations of its surface residues, and (3), a domain swapping mechanism, replacing one segment in a monomer by an equivalent segment from an identical chain in the dimer. Some of the dimers which are governed by a domain swapping mechanism may have evolved at an earlier stage of evolution via the second mechanism. Here, we follow the theory that the kinetic pathway reflects the evolutionary pathway. We analyze the structure-kinetics-evolution relationship for a collection of symmetric homodimers classified into three groups: (1) 14 dimers, which were referred to as domain swapping dimers in the literature; (2) nine 2-state dimers, which have no measurable intermediates in equilibrium denaturation; and (3), eight 3-state dimers, which have stable intermediates in equilibrium denaturation. The analysis consists of the following stages: (i) The dimer is divided into two structural units, which have twofold symmetry. Each unit contains a contiguous segment from one polypeptide chain of the dimer, and its complementary contiguous segment from the other chain. (ii) The division is repeated progressively, with different combinations of the two segments in each unit. (iii) The coefficient of compactness is calculated for the units in all divisions. The coefficients obtained for different cuttings of a dimer form a compactness profile. The profile probes the structural organization of the two chains in a dimer and the stability of the monomeric state. We describe the features of the compactness profiles in each of the three dimer groups. The profiles identify the swapping segments in domain swapping dimers

  5. The cyanogenic glucoside composition of Zygaena filipendulae (Lepidoptera: Zygaenidae) as effected by feeding on wild-type and transgenic lotus populations with variable cyanogenic glucoside profiles.

    PubMed

    Zagrobelny, Mika; Bak, Søren; Ekstrøm, Claus Thorn; Olsen, Carl Erik; Møller, Birger Lindberg

    2007-01-01

    Zygaena larvae sequester the cyanogenic glucosides linamarin and lotaustralin from their food plants (Fabaceae) as well as carry out de novo biosynthesis of these compounds. In this study, Zygaena filipendulae were reared on wild-type Lotus corniculatus and wild-type and transgenic L. japonicus plants with differing content and ratios of the cyanogenic glucosides linamarin and lotaustralin and of the cyanoalkenyl glucosides rhodiocyanoside A and D. LC-MS analyses, free choice feeding experiments and developmental studies were used to examine the effect of varying content and ratios of these secondary metabolites on the feeding preferences, growth and development of Z. filipendulae. Larvae reared on cyanogenic L. corniculatus developed faster compared to larvae reared on L. japonicus although free choice feeding trials demonstrated that the latter plant source was the preferred food plant. Larvae reared on acyanogenic L. corniculatus showed decelerated development. Analysis of different life stages and tissues demonstrate that Z. filipendulae strive to maintain certain threshold content and ratios of cyanogenic glucosides regardless of the composition of the food plants. Despite this, the ratios of cyanogenic glucosides in Z. filipendulae remain partly affected by the ratio of the food plant due to the high proportion of sequestering that takes place.

  6. Olive leaf components apigenin 7-glucoside and luteolin 7-glucoside direct human hematopoietic stem cell differentiation towards erythroid lineage.

    PubMed

    Samet, Imen; Villareal, Myra O; Motojima, Hideko; Han, Junkyu; Sayadi, Sami; Isoda, Hiroko

    2015-06-01

    The generation of blood cellular components from hematopoietic stem cells is important for the therapy of a broad spectrum of hematological disorders. In recent years, several lines of evidence suggested that certain nutrients, vitamins and flavonoids may have important roles in controlling the stem cell fate decision by maintaining their self-renewal or stimulating the lineage-specific differentiation. In this study, main olive leaf phytochemicals oleuropein (Olp), apigenin 7-glucoside (Api7G) and luteolin 7-glucoside (Lut7G) were investigated for their potential effects on hematopoietic stem cell differentiation using both phenotypic and molecular analysis. Oleuropein and the combination of the three compounds enhanced the differentiation of CD34+ cells into myelomonocytic cells and lymphocytes progenitors and inhibited the commitment to megakaryocytic and erythroid lineages. Treatment with Lut7G stimulated both the erythroid and the myeloid differentiation, while treatment with Api7G specifically induced the differentiation of CD34+ cells towards the erythroid lineage and inhibited the myeloid differentiation. Erythroid differentiation induced by Api7G and Lut7G treatments was confirmed by the increase in hemoglobin genes expressions (α-hemoglobin, β-hemoglobin and γ-hemoglobin) and erythroid transcription factor GATA1 expression. As revealed by microarray analysis, the mechanisms underlying the erythroid differentiation-inducing effect of Api7G on hematopoietic stem cells involves the activation of JAK/STAT signaling pathway. These findings prove the differentiation-inducing effects of olive leaf compounds on hematopoietic stem cells and highlight their potential use in the ex vivo generation of blood cells. Copyright © 2015 International Society of Differentiation. Published by Elsevier B.V. All rights reserved.

  7. Dimer crystallization of chiral proteoids.

    PubMed

    Wang, Po-Yuan; Mason, Thomas G

    2017-03-08

    Proteins can self-assemble into a variety of exquisitely organized structures through hierarchical reaction pathways. To examine how different core shapes of proteins and entropy combine to influence self-assembly, we create systems of lithographically fabricated proteomimetic colloids, or 'proteoids', and explore how Brownian monolayers of mobile proteoids, which have hard interactions, self-assemble as they are slowly crowded. Remarkably, chiral C-shaped proteoids having circular heads on only one side form enantiopure lock-and-key chiral dimers; these dimers have corrugated, shape-complementary perimeters, so they, in turn, form lock-and-key arrangements into chiral dimer crystals. Time-lapse video microscopy reveals the expulsion of monomers from the growing dimer crystals through tautomerization translocation reactions which expedite the crystallization kinetics. By lithographically mutating proteoids, we also tune the types and structures of the resulting dimer crystals. Thus, rational design of sub-particle features in hard-core colloidal shapes can be used to sterically select desired self-assembly pathways without introducing any site-specific attractions, thereby generating a striking degree of hierarchical self-ordering, reminiscent of protein crystallization.

  8. Haldane relation for interacting dimers

    NASA Astrophysics Data System (ADS)

    Giuliani, Alessandro; Mastropietro, Vieri; Lucio Toninelli, Fabio

    2017-03-01

    We consider a model of weakly interacting close-packed dimers on the two-dimensional square lattice. In a previous paper, we computed both the multi-point dimer correlations, which display non-trivial critical exponents, continuously varying with the interaction strength; and the height fluctuations, which, after proper coarse graining and rescaling, converge to a massless Gaussian field with a suitable interaction-dependent pre-factor (‘amplitude’). In this paper, we prove the identity between the critical exponent of the two-point dimer correlation and the amplitude of this massless Gaussian field. This identity is the restatement, in the context of interacting dimers, of one of the Haldane universality relations, part of his Luttinger-liquid conjecture, originally formulated in the context of one-dimensional interacting Fermi systems. Its validity is a strong confirmation of the effective massless Gaussian field description of the interacting dimer model, which was proposed on the basis of formal bosonization arguments. We also conjecture that a certain discrete curve defined at the lattice level via the Temperley bijection converges in the scaling limit to an SLE κ process, with κ depending non-trivially on the interaction and related in a simple way to the amplitude of the limiting Gaussian field.

  9. Adventures in Holographic Dimer Models

    SciTech Connect

    Kachru, Shamit; Karch, Andreas; Yaida, Sho; /Stanford U., Phys. Dept.

    2011-08-12

    We abstract the essential features of holographic dimer models, and develop several new applications of these models. Firstly, semi-holographically coupling free band fermions to holographic dimers, we uncover novel phase transitions between conventional Fermi liquids and non-Fermi liquids, accompanied by a change in the structure of the Fermi surface. Secondly, we make dimer vibrations propagate through the whole crystal by way of double trace deformations, obtaining nontrivial band structure. In a simple toy model, the topology of the band structure experiences an interesting reorganization as we vary the strength of the double trace deformations. Finally, we develop tools that would allow one to build, in a bottom-up fashion, a holographic avatar of the Hubbard model.

  10. Adventures in holographic dimer models

    NASA Astrophysics Data System (ADS)

    Kachru, Shamit; Karch, Andreas; Yaida, Sho

    2011-03-01

    We abstract the essential features of holographic dimer models, and develop several new applications of these models. Firstly, semi-holographically coupling free band fermions to holographic dimers, we uncover novel phase transitions between conventional Fermi liquids and non-Fermi liquids, accompanied by a change in the structure of the Fermi surface. Secondly, we make dimer vibrations propagate through the whole crystal by way of double trace deformations, obtaining nontrivial band structure. In a simple toy model, the topology of the band structure experiences an interesting reorganization as we vary the strength of the double trace deformations. Finally, we develop tools that would allow one to build, in a bottom-up fashion, a holographic avatar of the Hubbard model.

  11. Synthesis of defined ubiquitin dimers.

    PubMed

    Eger, Silvia; Scheffner, Martin; Marx, Andreas; Rubini, Marina

    2010-11-24

    Many proteins are post-translationally modified by the attachment of poly-ubiquitin (Ub) chains. Notably, the biological function of the attached Ub chain depends on the specific lysine residue used for conjugate formation. Here, we report an easy and efficient method to synthesize site-specifically linked Ub dimers by click reaction between two artificial amino acids. In fact, we were able to synthesize all seven naturally occurring Ub connectivities, providing the first example of a method that gives access to all Ub dimers. Furthermore, these synthetic Ub dimers are recognized by the natural ubiquitination machinery and are proteolytically stable, making them optimal candidates to further investigate the function of differently linked Ub chains.

  12. Small intestinal hydrolysis of plant glucosides: higher glucohydrolase activities in rodents than passerine birds.

    PubMed

    Lessner, Krista M; Dearing, M Denise; Izhaki, Ido; Samuni-Blank, Michal; Arad, Zeev; Karasov, William H

    2015-09-01

    Glycosides are a major group of plant secondary compounds characterized by one or more sugars conjugated to a lipophilic, possibly toxic aglycone, which is released upon hydrolysis. We compared small intestinal homogenate hydrolysis activity of three rodent and two avian species against four substrates: amygdalin and sinigrin, two plant-derived glucosides, the sugar lactose, whose hydrolysis models some activity against flavonoid and isoflavonoid glucosides, and the disaccharide sugar maltose (from starch), used as a comparator. Three new findings extend our understanding of physiological processing of plant glucosides: (1) the capacity of passerine birds to hydrolyze plant glucosides seems relatively low, compared with rodents; (2) in this first test of vertebrates' enzymic capacity to hydrolyze glucosinolates, sinigrin hydrolytic capacity seems low; (3) in laboratory mice, hydrolytic activity against lactose resides on the enterocytes' apical membrane facing the intestinal lumen, but activity against amygdalin seems to reside inside enterocytes. © 2015. Published by The Company of Biologists Ltd.

  13. Presence of the Cyanogenic Glucoside Dhurrin in Isolated Vacuoles from Sorghum 1

    PubMed Central

    Saunders, James A.; Conn, Eric E.

    1978-01-01

    Large numbers of vacuoles (106-107) have been isolated from Sorghum bicolor protoplasts and analyzed for the cyanogenic glucoside dhurrin. Leaves from light-grown seedlings were incubated for 4 hours in 1.5% cellulysin and 0.5% macerase to yield mesophyll protoplasts which then were recovered by centrifugation, quantitated by a hemocytometer, and assayed for cyanogenic glucosides. Mature vacuoles, released from the protoplasts by osmotic shock, were purified on a discontinuous Ficoll gradient and monitored for intactness by their ability to maintain a slightly acid interior while suspended in an alkaline buffer as indicated by neutral red stain. Cyanide analysis of the protoplasts and the vacuoles obtained there from yielded equivalent values of 11 μmoles of cyanogenic glucoside dhurrin per 107 protoplasts or 107 vacuoles. This work supports an earlier study from this laboratory which demonstrated that the vacuole is the site of accumulation of the cyanogenic glucoside in Sorghum. ImagesFig. 1 PMID:16660251

  14. Thesinine-4'-O-beta-D-glucoside the first glycosylated plant pyrrolizidine alkaloid from Borago officinalis.

    PubMed

    Herrmann, Martina; Joppe, Holger; Schmaus, Gerhard

    2002-06-01

    The glycosylated pyrrolizidine alkaloid, thesinine-4'-O-beta-D-glucoside, has been isolated from the aqueous methanol extract of dried, defatted seeds of Borago officinalis (Boraginaceae). The structure was established by means of spectroscopic and chemical analysis.

  15. New Eugenol Glucoside-based Derivative Shows Fungistatic and Fungicidal Activity against Opportunistic Candida glabrata.

    PubMed

    de Souza, Thiago Belarmino; Brito, Keila Mercês de Oliveira; Silva, Naiara Chaves; Rocha, Raissa Prado; de Sousa, Grasiely Faria; Duarte, Lucienir Pains; Coelho, Luiz Felipe Leomil; Dias, Amanda Latércia Tranches; Veloso, Marcia Paranho; Carvalho, Diogo Teixeira; Dias, Danielle Ferreira

    2016-01-01

    A new series of glucosides modified in their saccharide units were synthesized, evaluated against Candida sp., and compared to prototype 1, an eugenol tetracetyl glucoside previously synthesized and shown to be active against Candida glabrata. Among the new glucosides, benzyl derivative 5 was the most promising, showing fungistatic activity at IC50 18.1 μm against Candida glabrata (threefold higher than fluconazole) and fungicidal activity with a low IC90 value of 36.2 μm. Moreover, the cytotoxic activity of compound 5 (CC50 : 580.9 μm), tested in peripheral blood mononuclear cells, suggests its potential as an agent to treat Candida glabrata infections, with a selectivity index of 32. The new eugenol glucoside 5 may be considered as a novel structural pattern in the development of new anti-Candida drugs.

  16. Quantification of nitropropanoyl glucosides in karaka nuts before and after treatment.

    PubMed

    MacAskill, J J; Manley-Harris, M; Field, Richard J

    2015-05-15

    A high performance liquid chromatography (HPLC) method was developed to assay nitropropanoyl glucosides in the nuts of karaka (Corynocarpus laevigatus) a traditional food of New Zealand Māori. Levels of glucosides, measured as 3-nitropropanoic acid, ranged from 50.25 to 138.62 g kg(-1) (5.0-13.9% w/w) and were highest in nuts from unripe drupes; these levels are higher than any previously reported. Other parts of the drupe also contained nitropropanoyl glucosides but at lower levels than the nut. Treatment procedures to remove the glucosides from the nuts varied in their efficacy with soxhlet extraction removing 98.7% and prolonged boiling and cold water extraction both removing 96%. These findings confirm the traditional methods for preparation of these nuts for consumption. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Hypoglycaemic activity of an HMG-containing flavonoid glucoside, chamaemeloside, from Chamaemelum nobile.

    PubMed

    König, G M; Wright, A D; Keller, W J; Judd, R L; Bates, S; Day, C

    1998-10-01

    The 3-hydroxy-3-methylglutaric acid (HMG) containing flavonoid glucoside chamaemeloside, has been determined to have in vivo hypoglycaemic activity comparable to that of free HMG. An improved isolation scheme for obtaining chamaemeloside from Chamaemelum nobile is presented.

  18. A new C9 nor-isoprenoid glucoside from Rantherium suaveolens.

    PubMed

    Oueslati, M Habib; Ben Jannet, H; Mighri, Zine; Matthew, Susan; Abreu, Pedro M

    2007-08-01

    The new C(9) nor-isoprenoid 3-methyl-octa-1,5-diene-7-one-3-O-beta-D-glucopyranoside, named as ranthenone glucoside (1), together with the previously known 9-hydoxylinaloyl glucoside (2), sitosterol-3beta-O-[6'-palmitoyl-beta-D-glucopyranoside] (3), scopoletin (4), fraxetin (5), and scopolin (6), were isolated from the aerial parts of Rantherium suaveolens. The structures of these compounds were elucidated by extensive spectroscopic analysis.

  19. Biochemical mechanism of action of certain glucoside and nucleoside dialdehyde inhibitors

    SciTech Connect

    Kalbag, S.S.

    1985-01-01

    The periodate-oxidation products of 4-methyl umbelliferyl 7-..beta..-D-glucoside (MUGox), n-dodecyl ..beta..-D-glucoside (DGox), n-amyl-..beta..-D-glucoside (AGox), 6,7 dihydroxy 6-..beta..-D-glucoside (esculinox), 4-hydroxy phenyl ..beta..-D-glucoside (arbutinox), salicylaldehyde-..beta..-D-glucoside (helicinox), indoxyl-..beta..-D0-D-glucoside (IGox) and ..beta..-Naphthyl ..cap alpha..-D-glucoside (N..cap alpha..Gox) were synthesized and screened for activity against L1210 leukemia in-vitro. MUGox, DGox, Arbutinox, and Helicinox were the most active, having IC/sub 50/ values of 40, 48, 44, and 47 ..mu..M, respectively. MUGox was found to inhibit DNA, RNA and protein synthesis significantly in L1210 cells. Its effects on the in-vitro activity of 2-cycle purified bovine brain tubulin were examined. MUGOx inhibited tubulin assembly only minimally at 100 ..mu..M but stabilized assembled microtubules from depolymerization at the same concentration. MUGox was a noncompetitive inhibitor of wheat germ RNA polymerase II and E. coli RNA polymerase with respect to (/sup 3/H)UMP incorporation into RNA. MUGox bound one essential lysine in the wheat germ enzyme and two essential lysines in the E. coli enzyme. DGox and AGox produced mixed inhibition of wheat germ RNA polymerase II. The purine nucleoside analog 6-S-(acetylaminoethyl-1-naphthylamino-5-sulfonyl) thioinosine dicarboxaldehyde (AMPR-OP) noncompetitively blocked 0X174 DNA binding to E. coli RNA polymerase. It is tentatively concluded that AMPR-OP bound two lysine residues in the template binding subsite in addition to one lysine in the initiation subsite.

  20. Kinetics of DNA Tile Dimerization

    PubMed Central

    2015-01-01

    Investigating how individual molecular components interact with one another within DNA nanoarchitectures, both in terms of their spatial and temporal interactions, is fundamentally important for a better understanding of their physical behaviors. This will provide researchers with valuable insight for designing more complex higher-order structures that can be assembled more efficiently. In this report, we examined several spatial factors that affect the kinetics of bivalent, double-helical (DH) tile dimerization, including the orientation and number of sticky ends (SEs), the flexibility of the double helical domains, and the size of the tiles. The rate constants we obtained confirm our hypothesis that increased nucleation opportunities and well-aligned SEs accelerate tile–tile dimerization. Increased flexibility in the tiles causes slower dimerization rates, an effect that can be reversed by introducing restrictions to the tile flexibility. The higher dimerization rates of more rigid tiles results from the opposing effects of higher activation energies and higher pre-exponential factors from the Arrhenius equation, where the pre-exponential factor dominates. We believe that the results presented here will assist in improved implementation of DNA tile based algorithmic self-assembly, DNA based molecular robotics, and other specific nucleic acid systems, and will provide guidance to design and assembly processes to improve overall yield and efficiency. PMID:24794259

  1. Kinetics of DNA tile dimerization.

    PubMed

    Jiang, Shuoxing; Yan, Hao; Liu, Yan

    2014-06-24

    Investigating how individual molecular components interact with one another within DNA nanoarchitectures, both in terms of their spatial and temporal interactions, is fundamentally important for a better understanding of their physical behaviors. This will provide researchers with valuable insight for designing more complex higher-order structures that can be assembled more efficiently. In this report, we examined several spatial factors that affect the kinetics of bivalent, double-helical (DH) tile dimerization, including the orientation and number of sticky ends (SEs), the flexibility of the double helical domains, and the size of the tiles. The rate constants we obtained confirm our hypothesis that increased nucleation opportunities and well-aligned SEs accelerate tile-tile dimerization. Increased flexibility in the tiles causes slower dimerization rates, an effect that can be reversed by introducing restrictions to the tile flexibility. The higher dimerization rates of more rigid tiles results from the opposing effects of higher activation energies and higher pre-exponential factors from the Arrhenius equation, where the pre-exponential factor dominates. We believe that the results presented here will assist in improved implementation of DNA tile based algorithmic self-assembly, DNA based molecular robotics, and other specific nucleic acid systems, and will provide guidance to design and assembly processes to improve overall yield and efficiency.

  2. Hydrolytic fate of deoxynivalenol-3-glucoside during digestion

    PubMed Central

    Berthiller, Franz; Krska, Rudolf; Domig, Konrad J.; Kneifel, Wolfgang; Juge, Nathalie; Schuhmacher, Rainer; Adam, Gerhard

    2011-01-01

    Deoxynivalenol-3-β-d-glucoside (D3G), a plant phase II metabolite of the Fusarium mycotoxin deoxynivalenol (DON), occurs in naturally contaminated wheat, maize, oat, barley and products thereof. Although considered as a detoxification product in plants, the toxicity of this substance in mammals is currently unknown. A major concern is the possible hydrolysis of the D3G conjugate back to its toxic precursor mycotoxin DON during mammalian digestion. We used in vitro model systems to investigate the stability of D3G to acidic conditions, hydrolytic enzymes and intestinal bacteria, mimicking different stages of digestion. D3G was found resistant to 0.2 M hydrochloric acid for at least 24 h at 37 °C, suggesting that it will not be hydrolyzed in the stomach of mammals. While human cytosolic β-glucosidase also had no effect, fungal cellulase and cellobiase preparations could cleave a significant portion of D3G. Most importantly, several lactic acid bacteria such as Enterococcus durans, Enterococcus mundtii or Lactobacillus plantarum showed a high capability to hydrolyze D3G. Taken together these data indicate that D3G is of toxicological relevance and should be regarded as a masked mycotoxin. PMID:21878373

  3. Thermodynamics and kinetics of cyanidin 3-glucoside and caffeine copigments.

    PubMed

    Limón, Piedad M; Gavara, Raquel; Pina, Fernando

    2013-06-05

    The multiequilibrium system of reactions of cyanidin 3-glucoside at acidic and mildly acidic pH values was studied in the presence of caffeine as a copigment. The thermodynamic and kinetic constants were determined using the so-called direct and reverse pH jump experiments that were followed by conventional UV-vis spectroscopy or stopped flow coupled to a UV-vis detector, depending on the rate of the monitored process. Compared with that of free anthocyanin, the copigmentation with caffeine extends the domain of the flavylium cation up to less acidic pH values, while in a moderately acidic medium, the quinoidal base becomes more stabilized. As a consequence, the hydration to give the colorless hemiketal is difficult over the entire range of pH values. At pH 1, two adducts were found for the flavylium cation-caffeine interaction, with stoichiometries of 1:1 and 1:2 and association constants of 161 M⁻¹ (K₁) and 21 M⁻¹ (K₂), respectively.

  4. Characterization of mAb dimers reveals predominant dimer forms common in therapeutic mAbs

    PubMed Central

    Plath, Friederike; Ringler, Philippe; Graff-Meyer, Alexandra; Stahlberg, Henning; Lauer, Matthias E.; Rufer, Arne C.; Graewert, Melissa A.; Svergun, Dmitri; Gellermann, Gerald; Finkler, Christof; Stracke, Jan O.; Koulov, Atanas; Schnaible, Volker

    2016-01-01

    ABSTRACT The formation of undesired high molecular weight species such as dimers is an important quality attribute for therapeutic monoclonal antibody formulations. Therefore, the thorough understanding of mAb dimerization and the detailed characterization mAb dimers is of great interest for future pharmaceutical development of therapeutic antibodies. In this work, we focused on the analyses of different mAb dimers regarding size, surface properties, chemical identity, overall structure and localization of possible dimerization sites. Dimer fractions of different mAbs were isolated to a satisfactory purity from bulk material and revealed 2 predominant overall structures, namely elongated and compact dimer forms. The elongated dimers displayed one dimerization site involving the tip of the Fab domain. Depending on the stress applied, these elongated dimers are connected either covalently or non-covalently. In contrast, the compact dimers exhibited non-covalent association. Several interaction points were detected for the compact dimers involving the hinge region or the base of the Fab domain. These results indicate that mAb dimer fractions are rather complex and may contain more than one kind of dimer. Nevertheless, the overall appearance of mAb dimers suggests the existence of 2 predominant dimeric structures, elongated and compact, which are commonly present in preparations of therapeutic mAbs. PMID:27031922

  5. Water dimer equilibrium constant of saturated vapor

    NASA Astrophysics Data System (ADS)

    Malomuzh, N. P.; Mahlaichuk, V. N.; Khrapatyi, S. V.

    2014-08-01

    The value and temperature dependence of the dimerization constant for saturated water vapor are determined. A general expression that links the second virial coefficient and the dimerization constant is obtained. It is shown that the attraction between water monomers and dimers is fundamental, especially at T > 350 K. The range of application for the obtained results is determined.

  6. Synthesis of Octyl-β-Glucoside Catalyzed by Almond β-Glucosidase in Unconventional Reaction Media

    PubMed Central

    2016-01-01

    Summary The reaction system for octyl-β-glucoside synthesis catalysed by the almond-β-glucosidase has been characterised. The monophasic octanol saturated with different amounts of water served as a reaction medium. Both the glucose and the activated substrate p-nitrophenyl-β-glucoside were examined as glycon donors. The reverse hydrolysis and the transglycosylation were both used as reaction models for this enzymatically catalysed alkyl-β-glucoside synthesis. The rate of synthesis of octyl-β-glucoside (vS), the rate of hydrolysis, i.e. the glucose formation (vH) and the predicted yield (Y) were determined. The effect of water activity on the synthetic and hydrolytic activity of the enzyme was investigated. Both the rate of synthesis and the rate of hydrolysis increased with the increase of the water activity in the reaction system, showing their maximum values at the water activity close to the saturation level. Thus, the maximum ratio of vS/vH=0.165 was achieved at the water activity of 0.94. The predicted yields were 0.5, 0.75 and 14.19% and were lower than the actually achieved yields of 19.45, 38 and 36.40% at the water activities of 0.75, 0.84 and 0.94, respectively. The yield of octyl-β-glucoside in the reverse hydrolysis was only 15.2%, i.e. 3.25 times lower than the yield obtained in the transglycosylation reaction with the water activity of 0.94. The solubility of glucose in pure octanol was only 1.5 mmol/L at the saturation level of 12 mmol/L in the presence of 10 mmol/L of p-nitrophenyl-β-glucoside, and it increased to 15.5 mmol/L in the presence of octyl-β-glucoside. PMID:27904411

  7. Uptake of quercetin and quercetin 3-glucoside from whole onion and apple peel extracts by Caco-2 cell monolayers.

    PubMed

    Boyer, Jeanelle; Brown, Dan; Liu, Rui Hai

    2004-11-17

    Evidence suggests that regular consumption of fruits and vegetables may reduce the risk of chronic diseases, and phytochemicals from fruits and vegetables may be responsible for this health benefit. However, there is limited knowledge on the bioavailability of specific phytochemicals from whole fruits and vegetables. This study used Caco-2 cells to examine uptake of quercetin aglycon and quercetin 3-glucoside as purified compounds and from whole onion and apple peel extracts. Pure quercetin aglycon was absorbed by the Caco-2 cells in higher concentrations than quercetin 3-glucoside (p < 0.05). Caco-2 cells treated with quercetin 3-glucoside accumulated both quercetin 3-glucoside and quercetin. Caco-2 cells absorbed more onion quercetin aglycon than onion quercetin 3-glucoside (p < 0.05), and the percentage of onion quercetin absorbed was greater than that of pure quercetin, most likely due to enzymatic hydrolysis of quercetin 3-glucoside and other quercetin glucosides found in the onion by the Caco-2 cells. Caco-2 cells absorbed low levels of quercetin 3-glucoside from apple peel extracts, but quercetin aglycon absorption was not detected. Caco-2 cell homogenates demonstrated both lactase and glucosidase activities when incubated with lactose and quercetin 3-glucoside, respectively. This use of the Caco2 cell model appears to be a simple and useful system for studying bioavailability of whole food phytochemicals and may be used to assess differences in bioavailability between foods.

  8. In vitro effects of cholesterol β-D-glucoside, cholesterol and cycad phytosterol glucosides on respiration and reactive oxygen species generation in brain mitochondria.

    PubMed

    Panov, Alexander; Kubalik, Nataliya; Brooks, Benjamin R; Shaw, Christopher A

    2010-10-01

    The cluster of neurodegenerative disorders in the western Pacific termed amyotrophic lateral sclerosis-parkinsonism dementia complex (ALS-PDC) has been repeatedly linked to the use of seeds of various species of cycad. Identification and chemical synthesis of the most toxic compounds in the washed cycad seeds, a variant phytosteryl glucosides, and even more toxic cholesterol β-D-glucoside (CG), which is produced by the human parasite Helicobacter pylori, provide a possibility to study in vitro the mechanisms of toxicity of these compounds. We studied in detail the effects of CG on the respiratory activities and generation of reactive oxygen species (ROS) by nonsynaptic brain and heart mitochondria oxidizing various substrates. The stimulatory effects of CG on respiration and ROS generation showed strong substrate dependence, suggesting involvement of succinate dehydrogenase (complex II). Maximal effects on ROS production were observed with 1 μmol CG/1 mg mitochondria. At this concentration the cycad toxins β-sitosterol-β-D-glucoside and stigmasterol-β-D-glucoside had effects on respiration and ROS production similar to CG. However, poor solubility precluded full concentration analysis of these toxins. Cholesterol, stigmasterol and β-sitosterol had no effect on mitochondrial functions studied at concentrations up to 100 μmol/mg protein. Our results suggest that CG may influence mitochondrial functions through changes in the packing of the bulk membrane lipids, as was shown earlier by Deliconstantinos et al. (Biochem Cell Biol 67:16-24, 1989). The neurotoxic effects of phytosteryl glucosides and CG may be associated with increased oxidative damage of neurons. Unlike heart mitochondria, in activated neurons mitochondria specifically increase ROS production associated with succinate oxidation (Panov et al., J Biol Chem 284:14448-14456, 2009).

  9. Reactions of ultracold alkali-metal dimers

    SciTech Connect

    Zuchowski, Piotr S.; Hutson, Jeremy M.

    2010-06-15

    We investigate the energetics of reactions involving pairs of alkali-metal dimers. Atom exchange reactions to form homonuclear dimers are energetically allowed for some but not all of the heteronuclear dimers. We carry out high-level electronic structure calculations on the potential energy surfaces of all the heteronuclear alkali-metal trimers and show that trimer formation reactions are always energetically forbidden for low-lying singlet states of the dimers. The results have important implications for the stability of quantum gases of alkali-metal dimers.

  10. Metabolism of the masked mycotoxin deoxynivalenol-3-glucoside in rats.

    PubMed

    Nagl, Veronika; Schwartz, Heidi; Krska, Rudolf; Moll, Wulf-Dieter; Knasmüller, Siegfried; Ritzmann, Mathias; Adam, Gerhard; Berthiller, Franz

    2012-09-18

    Deoxynivalenol-3-β-D-glucoside (D3G), a plant metabolite of the Fusarium mycotoxin deoxynivalenol (DON), might be hydrolyzed in the digestive tract of mammals, thus contributing to the total dietary DON exposure of individuals. Yet, D3G has not been considered in regulatory limits set for DON for foodstuffs due to the lack of in vivo data. The aim of our study was to evaluate whether D3G is reactivated in vivo by investigation of its metabolism in rats. Six Sprague-Dawley rats received water, DON (2.0 mg/kg body weight (b.w.)) and the equimolar amount of D3G (3.1 mg/kg b.w.) by gavage on day 1, 8 and 15, respectively. Urine and feces were collected for 48 h and analyzed for D3G, DON, deoxynivalenol-glucuronide (DON-GlcA) and de-epoxy deoxynivalenol (DOM-1) by a validated LC-tandem mass spectrometry (MS/MS) based biomarker method. After administration of D3G, only 3.7±0.7% of the given dose were found in urine in the form of analyzed analytes, compared to 14.9±5.0% after administration of DON, and only 0.3±0.1% were detected in the form of urinary D3G. The majority of administered D3G was recovered as DON and DOM-1 in feces. These results suggest that D3G is little bioavailable, hydrolyzed to DON during digestion, and partially converted to DOM-1 and DON-GlcA prior to excretion. Our data indicate that D3G is of considerably lower toxicological relevance than DON, at least in rats.

  11. Fiber optic D dimer biosensor

    DOEpatents

    Glass, R.S.; Grant, S.A.

    1999-08-17

    A fiber optic sensor for D dimer (a fibrinolytic product) can be used in vivo (e.g., in catheter-based procedures) for the diagnosis and treatment of stroke-related conditions in humans. Stroke is the third leading cause of death in the United States. It has been estimated that strokes and stroke-related disorders cost Americans between $15-30 billion annually. Relatively recently, new medical procedures have been developed for the treatment of stroke. These endovascular procedures rely upon the use of microcatheters. These procedures could be facilitated with this sensor for D dimer integrated with a microcatheter for the diagnosis of clot type, and as an indicator of the effectiveness, or end-point of thrombolytic therapy. 4 figs.

  12. Fiber optic D dimer biosensor

    DOEpatents

    Glass, Robert S.; Grant, Sheila A.

    1999-01-01

    A fiber optic sensor for D dimer (a fibrinolytic product) can be used in vivo (e.g., in catheter-based procedures) for the diagnosis and treatment of stroke-related conditions in humans. Stroke is the third leading cause of death in the United States. It has been estimated that strokes and stroke-related disorders cost Americans between $15-30 billion annually. Relatively recently, new medical procedures have been developed for the treatment of stroke. These endovascular procedures rely upon the use of microcatheters. These procedures could be facilitated with this sensor for D dimer integrated with a microcatheter for the diagnosis of clot type, and as an indicator of the effectiveness, or end-point of thrombolytic therapy.

  13. Mechanism of FGF receptor dimerization and activation

    NASA Astrophysics Data System (ADS)

    Sarabipour, Sarvenaz; Hristova, Kalina

    2016-01-01

    Fibroblast growth factors (fgfs) are widely believed to activate their receptors by mediating receptor dimerization. Here we show, however, that the FGF receptors form dimers in the absence of ligand, and that these unliganded dimers are phosphorylated. We further show that ligand binding triggers structural changes in the FGFR dimers, which increase FGFR phosphorylation. The observed effects due to the ligands fgf1 and fgf2 are very different. The fgf2-bound dimer structure ensures the smallest separation between the transmembrane (TM) domains and the highest possible phosphorylation, a conclusion that is supported by a strong correlation between TM helix separation in the dimer and kinase phosphorylation. The pathogenic A391E mutation in FGFR3 TM domain emulates the action of fgf2, trapping the FGFR3 dimer in its most active state. This study establishes the existence of multiple active ligand-bound states, and uncovers a novel molecular mechanism through which FGFR-linked pathologies can arise.

  14. Synthesis of hexyl α-glucoside and α-polyglucosides by a novel Microbacterium isolate.

    PubMed

    Ojha, Swati; Mishra, Saroj; Kapoor, Sumeet; Chand, Subhash

    2013-06-01

    Alkyl-glucosides and alkyl-polyglucosides are the new-generation biodegradable surfactants with good emulsifying and wetting properties. The α-forms of these glucosides occur in antibiotics and also stimulate nasal absorption of many drugs. In this paper, we report the synthesis of hexyl α-glucoside and α-polyglucosides using cell-bound α-glucosidase activity of a novel strain of Microbacterium paraoxydans. A number of cell-bound glycosyl hydrolase activities were detected in the isolate with the maximum hydrolytic activity of 180 IU g(-1) dry wt cells on p-nitrophenyl-α-D-glucopyranoside. In a micro-aqueous system, at a water activity of 0.69, 1.8 g l(-1) of hexyl α-glucoside (corresponding to about 25 % yield) was synthesized by whole cells with maltose and hexanol as substrates. The concentration was enhanced to 11 g l(-1) (~60 % yield) in a biphasic system at a water content of 60 %. (1)H and (13)C NMR spectra of the purified compound confirmed the synthesized product to be hexyl-α-D-glucopyranoside, while the presence of hexyl di- and tri-glucosides was confirmed by electrospray ionization mass spectrometry. The cell-driven synthesis makes this an extremely attractive alternative for synthesis of such compounds.

  15. Enzyme bread improvers affect the stability of deoxynivalenol and deoxynivalenol-3-glucoside during breadmaking.

    PubMed

    Vidal, Arnau; Ambrosio, Asier; Sanchis, Vicente; Ramos, Antonio J; Marín, Sonia

    2016-10-01

    The stability of deoxynivalenol (DON) and deoxynivalenol-3-glucoside (DON-3-glucoside) during the breadmaking process was studied. Some enzymes used in the bakery industry were examined to evaluate their effects on DON and DON-3-glucoside. The level of DON in breads without added enzymes was reduced (17-21%). Similarly, the addition of cellulase, protease, lipase and glucose-oxidase did not modify this decreasing trend. The effect of xylanase and α-amylase on DON content depended on the fermentation temperature. These enzymes reduced the DON content by 10-14% at 45°C. In contrast, at 30°C, these enzymes increased the DON content by 13-23%. DON-3-glucoside levels decreased at the end of fermentation, with a final reduction of 19-48% when no enzymes were used. However, the presence of xylanase, α-amylase, cellulase and lipase resulted in bread with greater quantities of DON-3-glucoside when fermentation occurred at 30°C. The results showed that wheat bran and flour may contain hidden DON that may be enzymatically released during the breadmaking process when the fermentation temperature is close to 30°C.

  16. Structure-activity relationships of oligo-beta-glucoside elicitors of phytoalexin accumulation in soybean.

    PubMed Central

    Cheong, J J; Birberg, W; Fügedi, P; Pilotti, A; Garegg, P J; Hong, N; Ogawa, T; Hahn, M G

    1991-01-01

    The abilities of a family of chemically synthesized oligo-beta-glucosides, ranging in size from hexamer to decamer, to induce phytoalexin accumulation in soybean cotyledons were investigated to determine which structural elements of the oligoglucosides are important for their biological activity. The results of the biological assays established that the following structural motif is necessary for the oligo-beta-glucosides to have high elicitor activity: [formula; see text] The branched trisaccharide at the nonreducing end of the oligoglucosides was found to be essential for maximum elicitor activity. Substitution of either the nonreducing terminal backbone glucosyl residue or the side-chain glucosyl residue closest to the nonreducing end with glucosaminyl or N-acetylglucosaminyl residues reduced the elicitor activity of the oligoglucosides between 10-fold and 10,000-fold. Elicitor activity was also reduced 1000-fold if the two side-chain glucosyl residues were attached to adjacent backbone glucosyl residues rather than to glucosyl residues separated by an unbranched residue. In contrast, modifications of the reducing terminal glucosyl residue of an elicitor-active hepta-beta-glucoside by conjugation with tyramine and subsequent iodination had no significant effect on the elicitor activity of the hepta-beta-glucoside. These results demonstrate that oligo-beta-glucosides must have a specific structure to trigger the signal transduction pathway, which ultimately leads to the de novo synthesis of phytoalexins in soybean. PMID:1840904

  17. Liquid chromatography coupled to nuclear magnetic resonance spectroscopy for the identification of isoflavone glucoside malonates in T. pratense L. leaves.

    PubMed

    de Rijke, Eva; de Kanter, Frans; Ariese, Freek; Brinkman, Udo A Th; Gooijer, Cees

    2004-09-01

    Previous studies revealed that the main isoflavones in extracts of leaves of T. pratense L. are biochanin A and formononetin, their 7-O-glucosides, and two glucoside malonate isomers of each of them. Since LC-MS(/MS) did not provide sufficient information to distinguish the glucoside malonate isomers, in the present paper LC-NMR as well as off-line two-dimensional NMR were used to obtain further structural information. Matrix solid-phase dispersion (MSPD) was applied to obtain sufficiently high analyte concentrations to perform LC-NMR. Stop-flow reversed-phase LC-NMR was performed using a gradient of deuterated water and deuterated acetonitrile. Offline COSY and NOESY experiments were carried out to determine the positions of the glucose moiety on the flavonoid aglycone, and of the malonate moiety on the glucose. Based on the fragmentation patterns in MS/MS and the NMR spectra, the two formononetin glucoside malonate isomers were identified as 7-O-beta-D-glucoside 6"-O-malonate and 7-O-beta-D-glucoside 4"-O-malonate; i.e. they only differ in the substitution position of the malonate group on the glucoside ring. The biochanin A glucoside malonate isomers, however, have quite different structures. The main and later eluting isomer is biochanin A 7-O-beta-D-glucoside 6"-O-malonate, and the minor and earlier eluting isomer is 5-hydroxy-7-methoxyisoflavone 4'-O-beta-D-glucoside 4"-O-malonate: the positions of the methoxy group and the glucoside 6"-O-malonate group on the flavonoid skeleton are interchanged.

  18. Enzymatic synthesis and characterization of arbutin glucosides using glucansucrase from Leuconostoc mesenteroides B-1299CB.

    PubMed

    Moon, Young Hwan; Nam, Seung Hee; Kang, Jin; Kim, Young-Min; Lee, Jin-Ha; Kang, Hee-Kyung; Breton, Vincent; Jun, Woo-Jin; Park, Ki-Deok; Kimura, Atsuo; Kim, Doman

    2007-12-01

    Two arbutin glucosides were synthesized via the acceptor reaction of a glucansucrase from Leuconostoc mesenteroides B-1299CB with arbutin and sucrose. The glucosides were purified by Bio-gel P-2 column chromatography and high-performance liquid chromatography, and the structures were elucidated as 4-hydroxyphenyl beta-isomaltoside (arbutin-G1), 4-hydroxyphenyl beta-isomaltotrioside (arbutin-G2), according to the results of (1)H, (13)C, heteronuclear single-quantum coherence, (1)H-(1)H COSY, and heteronuclear multiple-bond correlation analyses. Arbutin glucoside (4-hydroxyphenyl beta-isomaltoside) exhibited slower effects on 1,1-diphenyl-2-picrylhydrazyl radical scavenging and similar effects on tyrosinase inhibition, and increased inhibitory effect on matrix metalloproteinase-1 production induced by UVB than arbutin.

  19. Acylated anthocyanidin 3-sophoroside-5-glucosides from Ajuga reptans flowers and the corresponding cell cultures.

    PubMed

    Terahara, N; Callebaut, A; Ohba, R; Nagata, T; Ohnishi-Kameyama, M; Suzuki, M

    2001-10-01

    Four anthocyanins from Ajuga reptans flowers and its cell cultures were isolated, and a fifth was also characterized by HPLC-mass spectrometry. By means of chemical and spectroscopic analyses, their structures were identified as delphinidin 3-(p-coumaroyl-feruloyl)sophoroside-5-malonylglucoside, delphinidin 3-(diferuloyl)sophoroside-5-malonylglucoside, and cyanidin 3-(di-p-coumaroyl)sophoroside-5-glucoside, respectively. The other two were tentatively identified as delphinidin 3-(diferuloyl)sophoroside-5-glucoside and cyanidin 3-(feruloyl-p-coumaroyl)sophoroside-5-malonylglucoside. In neutral aqueous solution, the crude extract from A. reptans flower cell cultures and the major anthocyanin cyanidin 3-(di-p-coumaroyl)sophoroside-5-malonylglucoside were more stable than cyanidin 3-glucoside, and also prevented more efficiently peroxidation than did the latter. A. reptans flower cell culture anthocyanins may have a potential as natural colorants for food utilities or other purposes.

  20. Ailanthus altissima (Miller) Swingle fruit - new acyl β-sitosteryl glucoside and in vitro pharmacological evaluation.

    PubMed

    Khan, Sohail; Hussain, Aftab; Mehmood, Ansar; Mehmood, Rashad; Perveen, Shagufta; Imran, Muhammad

    2016-01-21

    β-Sitosterol-3-O-(6'-O-13"-octadecenoyl)-β-D-glucoside (1), a new acyl β-sitosteryl glucoside, along with three known compounds β-sitosterol-3-O-β-D-glucoside (2), β-sitosterol (3) and methyl gallate (4) have been isolated from the ethyl acetate soluble fraction of methanolic extract of Ailanthus altissima fruits. Their structures were elucidated through spectroscopic data including 2D NMR, ESI-MS, methanolysis and oxidative cleavage of double bond. Antibacterial, antifungal, cytotoxic, phytotoxic and insecticidal activities were evaluated of compound 1, crude extract and its fractions so far for the first time. Pharmacological activities results showed that n-butanol fraction was good active against Pseudomonas aeruginosa and Salmonella typhi bacteria, and moderate active against Microsporum canis fungus. Crude extract, n-butanol and aqueous fractions showed good cytotoxicity. Moreover, compound 1, extract and all fractions showed notable phytotoxicity at higher concentrations, whereas all inactive against assayed insects.

  1. Hydroxylation and glucoside conjugation in the microbial metabolism of the diterpene sclareol.

    PubMed

    Kouzi, S A; McChesney, J D

    1991-10-01

    1. The microbial metabolism of sclareol (1), a labdane diterpene ditertiary alcohol, was studied. Preliminary screening identified a number of microorganisms capable of metabolizing sclareol. 2. Preparative scale fermentation of growing cultures of Bacillus cereus UI-1477 resulted in the production of seven metabolites which have been characterized as 3 beta-hydroxysclareol (2), 2 alpha-hydroxysclareol (3), 18-hydroxysclareol (4), 2 alpha,18-dihydroxysclareol (6), 8 alpha,13 beta-dihydroxy-labd-14-en-3 beta-O-beta-D-glucoside (5), 8 alpha,13 beta-dihydroxy-labd-14-en-18-O-beta-D-glucoside (7), and 8 alpha,13 beta-dihydroxy-labd-14-en-2 alpha-O-beta-D-glucoside (10) by chemical, enzymic, and spectral data, especially 2D-n.m.r. techniques and thermospray liquid chromatography-mass spectrometry analysis.

  2. Hexyl glucoside and hexyl maltoside inhibit light-induced oxidation of tryptophan.

    PubMed

    Adem, Yilma T; Molina, Patricia; Liu, Hongbin; Patapoff, Thomas W; Sreedhara, Alavattam; Esue, Osigwe

    2014-02-01

    We investigated the photo-protective effect of sugar-based surfactants--hexyl glucoside and hexyl maltoside--against light-induced oxidation of a monoclonal antibody. Reactive oxygen species are generated in solutions in the presence of light; these reactive species readily oxidize amino acids such as tryptophan. Hexyl glucosides and hexyl maltosides scavenge these reactive species and protect tryptophan residues from light-induced oxidation in a concentration-dependent manner. As a result of the scavenging process, hydrogen peroxide is formed, especially at high (millimolar) concentrations of the alkyl glycoside surfactants. These results suggest that hexyl glucoside and hexyl maltoside have the potential to protect tryptophan residues against light-induced oxidation.

  3. Protective effect of tetrahydroxy stilbene glucoside on learning and memory by regulating synaptic plasticity

    PubMed Central

    Luo, Hong-bo; Li, Yun; Liu, Zun-jing; Cao, Li; Zhang, Zhi-qiang; Wang, Yong; Zhang, Xiao-yan; Liu, Zhao; Shi, Xiang-qun

    2016-01-01

    Damage to synaptic plasticity induced by neurotoxicity of amyloid-beta is regarded to be one of the pathological mechanisms of learning and memory disabilities in Alzheimer's disease patients. This study assumed that the damage of amyloid-beta to learning and memory abilities was strongly associated with the changes in the Fyn/N-methyl-D-aspartate receptor 2B (NR2B) expression. An APP695V7171 transgenic mouse model of Alzheimer's disease was used and treatment with tetrahydroxy-stilbene glucoside was administered intragastrically. Results showed that intragastric administration of tetrahydroxy-stilbene glucoside improved the learning and memory abilities of the transgenic mice through increasing NR2B receptors and Fyn expression. It also reversed parameters for synaptic interface structure of gray type I. These findings indicate that tetrahydroxy stilbene glucoside has protective effects on the brain, and has prospects for its clinical application to improve the learning and memory abilities and treat Alzheimer's disease. PMID:27857754

  4. Metabolism of the masked mycotoxin deoxynivalenol-3-glucoside in pigs.

    PubMed

    Nagl, Veronika; Woechtl, Bettina; Schwartz-Zimmermann, Heidi Elisabeth; Hennig-Pauka, Isabel; Moll, Wulf-Dieter; Adam, Gerhard; Berthiller, Franz

    2014-08-17

    Plants can metabolize the Fusarium mycotoxin deoxynivalenol (DON) by forming the masked mycotoxin deoxynivalenol-3-β-D-glucoside (D3G). D3G might be cleaved during digestion, thus increasing the total DON burden of an individual. Due to a lack of in vivo data, D3G has not been included in the various regulatory limits established for DON so far. The aim of our study was to contribute to the risk assessment of D3G by determination of its metabolism in pigs. Four piglets received water, D3G (116 μg/kg b.w.) and the equimolar amount of DON (75 μg/kg b.w.) by gavage on day 1, 5 and 9 of the experiment, respectively. Additionally, 15.5 μg D3G/kg b.w. were administered intravenously on day 13. Urine and feces were collected for 24 h and analyzed for DON, D3G, deoxynivalenol-3-glucuronide (DON-3-GlcA), deoxynivalenol-15-GlcA (DON-15-GlcA) and deepoxy-deoxynivalenol (DOM-1) by UHPLC-MS/MS. After oral application of DON and D3G, in total 84.8±9.7% and 40.3±8.5% of the given dose were detected in urine, respectively. The majority of orally administered D3G was excreted in form of DON, DON-15-GlcA, DOM-1 and DON-3-GlcA, while urinary D3G accounted for only 2.6±1.4%. In feces, just trace amounts of metabolites were found. Intravenously administered D3G was almost exclusively excreted in unmetabolized form via urine. Data indicate that D3G is nearly completely hydrolyzed in the intestinal tract of pigs, while the toxin seems to be rather stable after systemic absorption. Compared to DON, the oral bioavailability of D3G and its metabolites seems to be reduced by a factor of up to 2, approximately.

  5. Isolation of a novel carotenoid, OH-chlorobactene glucoside hexadecanoate, and related rare carotenoids from Rhodococcus sp. CIP and their antioxidative activities.

    PubMed

    Osawa, Ayako; Kasahara, Asami; Mastuoka, Shoko; Gassel, Sören; Sandmann, Gerhard; Shindo, Kazutoshi

    2011-01-01

    In the course of screening for antioxidative carotenoids from bacteria, we isolated and identified a novel carotenoid, OH-chlorobactene glucoside hexadecanoate (4), and rare carotenoids, OH-chlorobactene glucoside (1), OH-γ-carotene glucoside (2) and OH-4-keto-γ-carotene glucoside hexadecanoate (3) from Rhodococcus sp. CIP. The singlet oxygen ((1)O(2)) quenching model of these carotenoids showed potent antioxidative activities IC(50) 14.6 µM for OH-chlorobactene glucoside hexadecanoate (4), 6.5 µM for OH-chlorobactene glucoside (1), 9.9 µM for OH-γ-carotene glucoside (2) and 7.3 µM for OH-4-keto-γ-carotene glucoside hexadecanoate (3).

  6. Further characterization and regulation of malonyl-coenzyme A: flavonoid glucoside malonyltransferases from parsley cell suspension cultures

    SciTech Connect

    Matern, U.; Feser, C.; Hammer, D.

    1983-10-01

    Two malonyltransferases, malonyl-CoA:flavone/flavonol 7-O-glucoside malonyltransferase and malonyl-CoA:flavonol 3-O-glucoside malonyltransferase, were purified to apparent homogeneity from uv-irradiated parsley cell cultures. Both purified enzymes appear to be specific for flavonoid glycosides. Additional malonyltransferases, active toward several phenol glucosides other than flavonoids, were present in partially purified 7-O-glucoside malonyltransferase preparations. Antibodies raised against the purified 3-O-glucoside malonyltransferase did not inhibit the activity of the 7-O-glucoside malonyltransferase over a wide antibody concentration range. Determination of the rate of synthesis in vivo of the 3-O-glucoside malonyltransferase after ultraviolet light-pulse induction of parsley cells revealed two maxima at 6 and 30 h, respectively. These results indicate that the induced changes in 3-O-glucoside malonyltransferase activity were the consequence of either a repeated change in the rate of synthesis of one enzyme species or changes in the synthesis rates of more than one enzyme species.

  7. Isolation of Biopterin-alpha-glucoside from Spirulina (Arthrospira) platensis and Its Physiologic Function.

    PubMed

    Noguchi; Ishii; Matsushima; Haishi; Yasumuro; Moriguchi; Wada; Kodera; Hiroto; Nishimura; Sekine; Inada

    1999-03-01

    : A fluorescent substance was isolated from the cyanobacterium with a yield of 4.5 mg per 10 g of dried Spirulina (Arthrospira) platensis cells by gentle extraction and ethanol fractionation followed by column chromatography. The fluorescent substance, which has absorption maxima at 256 nm and 362 nm (pH 8.4), was identified as biopterin-alpha-glucoside by spectrophotometry and nuclear magnetic resonance spectroscopy. Biopterin-alpha-glucoside prevented decolorization of the photosynthetic pigments, chlorophyll a, phycocyanin, and carotenoids in photosynthetic vesicles of Spirulina platensis cells, by ultraviolet irradiation.

  8. Oximes, nitriles and 2-hydroxynitriles as precursors in the biosynthesis of cyanogenic glucosides

    PubMed Central

    Tapper, B. A.; Butler, G. W.

    1971-01-01

    The biosynthesis of the cyanogenic glucosides, linamarin and prunasin, was investigated in linen-flax, peach and cherry-laurel shoots. It was shown that related 2-oximino acids, aldoximes, nitriles and 2-hydroxynitriles were generally good precursors of the aglycone moiety. Studies with double-labelled compounds confirmed the retention of the oximino nitrogen atom from 2-oximinoisovaleric acid and isobutyraldoxime in the biosynthesis of linamarin. A general pathway from amino acids to cyanogenic glucosides involving N-hydroxyamino acids, aldoximes, nitriles and 2-hydroxynitriles is proposed. PMID:5131015

  9. Identification of delphinidin 3-O-(6''-O-malonyl)-beta-glucoside-3'-O-beta-glucoside, a postulated intermediate in the biosynthesis of ternatin C5 in the blue petals of Clitoria ternatea (butterfly pea).

    PubMed

    Kazuma, Kohei; Kogawa, Koichiro; Noda, Naonobu; Kato, Naoki; Suzuki, Masahiko

    2004-11-01

    Ternatins are blue anthocyanins found in the petals of Clitoria ternata (butterfly pea). Among them, ternatin C5 (delphinidin 3-O-(6''-O-malonyl)-beta-glucoside-3',5'-di-O-beta-glucoside; 2) has the structure common to all the ternatins, which is characterized by its glucosylation pattern: a 3,3',5'-triglucosylated anthocyanidin. In the course of studying biosynthetic pathways of ternatins, the key enzymatic activities to produce ternatin C5 were discovered in a crude enzyme preparation from the petals of a blue petal line of C. ternatea. When this preparation was tested for activity against several delphinidin glycosides, delphinidin 3-O-(6''-O-malonyl)-beta-glucoside-3'-O-beta-glucoside (6), a postulated intermediate, was found in the reaction mixture, together with three known anthocyanins, which were spectroscopically structurally identified. As a result of structural identification, the following enzymatic activities were identified: UDP-glucose :delphinidin 3-O-(6''-O-malonyl)-beta-glucoside-3'-O-beta-glucoside 5'-O-glucosyltransferase (5'GT), UDP-glucose :delphinidin 3-O-(6''-O-malonyl)-beta-glucoside 3'-O-glucosyltransferase (3'GT), UDP-glucose :delphinidin 3-O-glucosyltransferase, and malonyl-CoA :delphinidin 3-O-beta-glucoside 6''-malonyltransferase. In a mauve petal line, which did not accumulate ternatins but delphinidin 3-O-(6''-O-malonyl)-beta-glucoside in its petal, there were neither 5'GT nor 3'GT activities. Thus, the early biosynthetic pathway of ternatins may be characterized by the stepwise transfer of two glucose residues to 3'- and 5'-position of delphinidin 3-O-(6''-O-malonyl)-beta-glucoside (1; Scheme) from UDP-glucose.

  10. Dimer geometry, amoebae and a vortex dimer model

    NASA Astrophysics Data System (ADS)

    Nash, Charles; O'Connor, Denjoe

    2017-09-01

    We present a geometrical approach and introduce a connection for dimer problems on bipartite and non-bipartite graphs. In the bipartite case the connection is flat but has non-trivial {Z}2 holonomy round certain curves. This holonomy has the universality property that it does not change as the number of vertices in the fundamental domain of the graph is increased. It is argued that the K-theory of the torus, with or without punctures, is the appropriate underlying invariant. In the non-bipartite case the connection has non-zero curvature as well as non-zero Chern number. The curvature does not require the introduction of a magnetic field. The phase diagram of these models is captured by what is known as an amoeba. We introduce a dimer model with negative edge weights which correspond to vortices. The amoebae for various models are studied with particular emphasis on the case of negative edge weights. Vortices give rise to new kinds of amoebae with certain singular structures which we investigate. On the amoeba of the vortex full hexagonal lattice we find the partition function corresponds to that of a massless Dirac doublet.

  11. D-Dimer elevation and adverse outcomes.

    PubMed

    Halaby, Rim; Popma, Christopher J; Cohen, Ander; Chi, Gerald; Zacarkim, Marcelo Rodrigues; Romero, Gonzalo; Goldhaber, Samuel Z; Hull, Russell; Hernandez, Adrian; Mentz, Robert; Harrington, Robert; Lip, Gregory; Peacock, Frank; Welker, James; Martin-Loeches, Ignacio; Daaboul, Yazan; Korjian, Serge; Gibson, C Michael

    2015-01-01

    D-Dimer is a biomarker of fibrin formation and degradation. While a D-dimer within normal limits is used to rule out the diagnosis of deep venous thrombosis and pulmonary embolism among patients with a low clinical probability of venous thromboembolism (VTE), the prognostic association of an elevated D-dimer with adverse outcomes has received far less emphasis. An elevated D-dimer is independently associated with an increased risk for incident VTE, recurrent VTE, and mortality. An elevated D-dimer is an independent correlate of increased mortality and subsequent VTE across a broad variety of disease states. Therefore, medically ill subjects in whom the D-dimer is elevated constitute a high risk subgroup in which the prospective evaluation of the efficacy and safety of antithrombotic therapy is warranted.

  12. Solitary waves in dimer binary collision model

    NASA Astrophysics Data System (ADS)

    Ahsan, Zaid; Jayaprakash, K. R.

    2017-01-01

    Solitary wave propagation in nonlinear diatomic (dimer) chains is a very interesting topic of research in the study of nonlinear lattices. Such waves were recently found to be supported by the essentially nonlinear granular lattice and Toda lattice. An interesting aspect of this discovery is attributed to the realization of a spectrum of the mass ratio (the only system parameter governing the dynamics) that supports the propagation of such waves corresponding to the considered interaction potential. The objective of this exposition is to explore solitary wave propagation in the dimer binary collision (BC) model. Interestingly, the dimer BC model supports solitary wave propagation at a discrete spectrum of mass ratios similar to those observed in granular and Toda dimers. Further, we report a qualitative and one-to-one correspondence between the spectrum of the mass ratio corresponding to the dimer BC model and those corresponding to granular and Toda dimer chains.

  13. Dimerization of Human Growth Hormone by Zinc

    NASA Astrophysics Data System (ADS)

    Cunningham, Brian C.; Mulkerrin, Michael G.; Wells, James A.

    1991-08-01

    Size-exclusion chromatography and sedimentation equilibrium studies demonstrated that zinc ion (Zn2+) induced the dimerization of human growth hormone (hGH). Scatchard analysis of 65Zn2+ binding to hGH showed that two Zn2+ ions associate per dimer of hGH in a cooperative fashion. Cobalt (II) can substitute for Zn2+ in the hormone dimer and gives a visible spectrum characteristic of cobalt coordinated in a tetrahedral fashion by oxygen- and nitrogen-containing ligands. Replacement of potential Zn2+ ligands (His18, His21, and Glu174) in hGH with alanine weakened both Zn2+ binding and hGH dimer formation. The Zn2+-hGH dimer was more stable than monomeric hGH to denaturation in guanidine-HCl. Formation of a Zn2+-hGH dimeric complex may be important for storage of hGH in secretory granules.

  14. Monomer-dimer problem on some networks

    NASA Astrophysics Data System (ADS)

    Wu, Ruijuan; Yan, Weigen

    2016-09-01

    Zhang et al. (2012) obtained the exact formula for the number of all possible monomer-dimer arrangements and the asymptotic growth constant on a scale-free small-world network. In this note, we generalize this result and obtain the exact solution on the monomer-dimer model on many networks. Particularly, we prove that these networks have the same asymptotic growth constant of the number of monomer-dimer arrangements.

  15. Structural determination of a nivalenol glucoside and development of an analytical method for the simultaneous determination of nivalenol and deoxynivalenol, and their glucosides, in wheat.

    PubMed

    Yoshinari, Tomoya; Sakuda, Shohei; Furihata, Kazuo; Furusawa, Hiroko; Ohnishi, Takahiro; Sugita-Konishi, Yoshiko; Ishizaki, Naoto; Terajima, Jun

    2014-02-05

    Trichothecene mycotoxins such as nivalenol and deoxynivalenol frequently contaminate foodstuffs. Recently, several trichothecene glucosides have been found in trichothecene-contaminated foods, and information about their chemistry, toxicity, and occurrence is required. In this study, a glucoside of nivalenol was isolated from nivalenol-contaminated wheat and was identified as nivalenol-3-O-β-D-glucopyranoside. Analytical methods using a multifunctional column or an immunoaffinity column have been developed for the simultaneous determination of nivalenol, nivalenol-3-O-β-D-glucopyranoside, deoxynivalenol, and deoxynivalenol-3-O-β-D-glucopyranoside in wheat. The methods were validated in a single laboratory, and recovery from wheat samples spiked at four levels ranged between 86.4 and 103.5% for the immunoaffinity column cleanup. These mycotoxins in contaminated wheat samples were quantitated by the validated method. Nivalenol-3-O-β-D-glucopyranoside was detected in the nivalenol-contaminated wheat, and the percentage of nivalenol-3-O-β-D-glucopyranoside to nivalenol ranged from 12 to 27%. This result indicates that the analytical method developed in this study is useful for obtaining data concerning the state and level of food contamination by nivalenol, deoxynivalenol, and their glucosides.

  16. Thermalization of a dimerized antiferromagnetic spin chain.

    PubMed

    Konstantinidis, N P

    2016-01-20

    Thermalization is investigated for the one-dimensional anisotropic antiferromagnetic Heisenberg model with dimerized nearest-neighbor interactions that break integrability. For this purpose the time evolution of local operator expectation values after an interacting quench is calculated directly with the Chebyshev polynomial expansion, and the deviation of the diagonal from the canonical thermal ensemble value is calculated for increasing system size for these operators. The spatial and spin symmetries of the Hamiltonian are taken into account to divide it into symmetry subsectors. The rate of thermalization is found to weaken with the dimerization parameter as the Hamiltonian evolves between two integrable limits, the non-dimerized and the fully dimerized where the chain breaks up into isolated dimers. This conclusion is supported by the distribution of the local operator off-diagonal elements between the eigenstates of the Hamiltonian with respect to their energy difference, which determines the strength of temporal fluctuations. The off-diagonal elements have a low-energy peak for small dimerization which facilitates thermalization, and originates in the reduction of spatial symmetry with respect to the non-dimerized limit. For increasing dimerization their distribution changes and develops a single low-energy maximum that relates to the fully dimerized limit and slows down thermalization.

  17. 21 CFR 573.660 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Methyl glucoside-coconut oil ester. 573.660 Section 573.660 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF...

  18. Antioxidant Activity of Quercetin and Its Glucosides from Propolis: A Theoretical Study.

    PubMed

    Zheng, Yan-Zhen; Deng, Geng; Liang, Qin; Chen, Da-Fu; Guo, Rui; Lai, Rong-Cai

    2017-08-08

    Among the multiple components of propolis, flavonoids contribute greatly to the antioxidant activities of propolis. Flavonoids mainly exist in the form of sugar-conjugated derivatives. Quercetin glycosides represent the predominant flavonoid fraction in propolis. In this work, density functional theory (DFT) calculations were applied to analyze the antioxidative properties of quercetin and its glucosides in the gas and in the liquid phase (ethanol, water). Three main antioxidant mechanisms, hydrogen atom transfer (HAT), single electron transfer followed by proton transfer (SET-PT) and sequential proton loss electron transfer (SPLET) were used to analyze the antioxidative capacity of the investigated compounds. Solvent effects dominantly affect SET-PT and SPLET. Thus, the thermodynamically preferred mechanism can be altered. HAT and SPLET are the thermodynamically dominant mechanisms in gas and solvent phases, respectively. Therefore, in the gas phase, the sequence of the antioxidative capacity is similar with the bond dissociation enthalpy values: quercetin > quercetin-5-O-glucoside > quercetin-7-O-glucoside > quercetin-3-O-glucoside > quercetin-3'-O-glucoside > quercetin-4'-O-glucoside. While, in the solvent phases, the sequence is similar with the proton affinity values: quercetin-4'-O-glucoside > quercetin-5-O-glucoside > quercetin > quercetin-3-O-glucoside > quercetin-7-O-glucoside > quercetin-3'-O-glucoside. OH groups in B-ring and C-ring contribute mainly to the antioxidative activities of quercetin and glucosides compared with A-ring.

  19. A new sweet dihydrochalcone-glucoside from leaves of Lithocarpus pachyphyllus (Kurz) Rehd. (Fagaceae).

    PubMed

    Qin, Xiang-Dong; Liu, Ji-Kai

    2003-01-01

    A new sweet dihydrochalcone-glucoside, trilobatin 2"-acetate (1), was isolated from the leaves of Lithocarpus pachyphyllus, together with phlorizin and trilobatin. The structures were established by spectroscopic methods, including one- and two-dimensional NMR (COSY, HMQC and HMBC).

  20. Ascorbic acid glucoside reduces neurotoxicity and glutathione depletion in mouse brain induced by nitrotriazole radiosensitazer.

    PubMed

    Cherdyntseva, Nadezda V; Ivanova, Anna A; Ivanov, Vladimir V; Cherdyntsev, Evgeny; Nair, Cherupally Krishnan Krishnan; Kagiya, Tsutomu V

    2013-01-01

    To investigate the potential of the anti-oxidant ascorbic acid glucoside (AA-2G) to modulate neurotoxicity induced by high doses of nitrotriazole radiosensitizer. Male and female C56Bl/6xCBA hybrid mice aged 8-14 weeks (weight 18-24 g) were used. Nitrotriazole drug radiosensitizer sanazole at a high dose of 2, 1 g/kg was per os administered to induce neurotoxicity at mice. Ascorbic acid glucoside was given 30 min before the sanazole administration. Serum ascorbic acid, brain glutathione level, as well as behavioral performance using open field apparatus were measured. Administration of high (non-therapeutic) doses of the nitrotriazole drug sanazole results in neurotoxicity in mice as evidenced from behavioral performance, emotional activity and depletion of the cellular antioxidant, glutathione, in the brain. The serum levels of ascorbic acid was also found reduced in high dose sanazole treated animals. Per os administration of ascorbic acid glucoside significantly reduced the neurotoxicity. This effect was associated with the prevention of glutathione depletion in mouse brain and restoring the ascorbic acid level in serum. Administration of ascorbic acid glucoside, but not ascorbic acid, before sanazole administration protected from sanazole-induced neurotoxicity by preventing the decrease in the brain reduced glutathione level and providing high level of ascorbic acid in plasma.

  1. Effect of different exposed lights on quercetin and quercetin glucoside content in onion (Allium cepa L.).

    PubMed

    Ko, Eun Young; Nile, Shivraj Hariram; Sharma, Kavita; Li, Guan Hao; Park, Se Won

    2015-07-01

    Quercetin and quercetin glucosides are the major flavonols present in onion (Allium cepa L.) and are predominantly present as quercetin, quercetin-3,4'-diglucoside and quercetin-4'-glucoside. Effect of different light wavelengths on onion after harvest and storage, with fluorescent, blue, red and ultra violet light influenced the quercetin and quercetin glucosides profile. In a peeled onion, all the light treatments elevated quercetin content in bulb. Among them, particularly fluorescent light effect was more eminent which stimulates the maximum synthesis of quercetin in onion. In case of whole onion bulb, skin and pulp showed different responses to light treatment, respectively. The pulp had the highest quercetin glucosides under blue light, whereas the lowest under fluorescent light. Onion skin showed nearly opposite pattern as compared to the pulp. In particular, light treatment proved to be a better way to increase the level of quercetin content in onions which might be utilized for industrial production of bioactive compounds from onion and onion waste products.

  2. Megastigmane Glucosides and Megastigmanes from the Leaves of Meliosma lepidota ssp. squamulata.

    PubMed

    Uemura, Yuka; Iwami, Mio; Kawakami, Susumu; Sugimoto, Sachiko; Matsunami, Katsuyoshi; Otsuka, Hideaki; Shinzato, Takakazu; Kawahata, Masatoshi; Yamaguchi, Kentaro

    2015-01-01

    From the leaves of Meliosma lepidota ssp. squamulata, megastigmane glucosides with spiro-structures and megastigmanes were isolated. Their structures were determined by X-ray crystallographic analyses and spectroscopic investigation. The absolute structures of the megastigmanes were determined by the modified Mosher's method.

  3. Serotonin 5-O-β-Glucoside and Its N-Methylated Forms in Citrus Genus Plants.

    PubMed

    Servillo, Luigi; Giovane, Alfonso; Casale, Rosario; D'Onofrio, Nunzia; Ferrari, Giovanna; Cautela, Domenico; Balestrieri, Maria Luisa; Castaldo, Domenico

    2015-04-29

    Citrus genus is characterized by a specific presence of indole metabolites deriving from the N-methylation of tryptamine and its hydroxylated form, 5-hydroxytryptamine (serotonin), which are likely involved in plant defense mechanisms. In this study, we identified for the first time the occurrence in Citrus plants of serotonin 5-O-β-glucoside and all its N-methylated derivatives, that is, N-methylserotonin 5-O-β-glucoside, N,N-dimethylserotonin (bufotenine) 5-O-β-glucoside, and N,N,N-trimethylserotonin (bufotenidine) 5-O-β-glucoside. The identification of the glucosylated compounds was based on mass spectrometric studies, hydrolysis by glucosidase, and in some cases, comparison to authentic compounds. Beside leaves, the distribution of the glucosylated forms and their aglycones in some Citrus species was evaluated in flavedo, albedo, juice, and seeds. The simultaneous presence of serotonin and its N-methylated derivatives, together with the corresponding glucosylated forms, is consistent with the occurrence of a metabolic pathway, specific for Citrus, aimed at potentiating the defensive response to biotic stress through the optimization of the production and use of the most toxic of such metabolites.

  4. Occurrence of deoxynivalenol and deoxynivalenol-3-glucoside in hard red spring wheat grown in the USA

    USDA-ARS?s Scientific Manuscript database

    Deoxynivalenol (DON) is a mycotoxin found in wheat that is infected with Fusarium fungus. DON may also be converted to a type of "masked mycotoxin," named deoxynivalenol-3-glucoside (D3G), as a result of detoxification process of the plant. Both DON and D3G are known to be toxic. Due to the lack o...

  5. Analysis of deoxynivalenol and deoxynivalenol-3-glucoside in hard red spring wheat inoculated with Fusarium graminearum

    USDA-ARS?s Scientific Manuscript database

    Deoxynivalenol (DON) is a mycotoxin which isproduced by plant pathogens such as Fusarium species. The formation of the "masked" mycotoxin deoxinyvalenol-3-glucoside (D3G) results from a defense mechanism the plant uses for detoxification. These two mycotoxins are important from the food safety poi...

  6. Five secoiridoid glucosides esterified with a cyclopentanoid monoterpene unit from Jasminum nudiflorum.

    PubMed

    Tanahashi, T; Takenaka, Y; Nagakura, N; Nishi, T

    2000-08-01

    Phytochemical study of the stems of Jasminum nudiflorum has led to the isolation of five new secoiridoid glucosides, jasnudiflosides D (1) and E (2) and nudiflosides A-C (3-5). The structures of these compounds were elucidated on the basis of chemical and spectroscopic evidence.

  7. Effect of different exposed lights on quercetin and quercetin glucoside content in onion (Allium cepa L.)

    PubMed Central

    Ko, Eun Young; Nile, Shivraj Hariram; Sharma, Kavita; Li, Guan Hao; Park, Se Won

    2014-01-01

    Quercetin and quercetin glucosides are the major flavonols present in onion (Allium cepa L.) and are predominantly present as quercetin, quercetin-3,4′-diglucoside and quercetin-4′-glucoside. Effect of different light wavelengths on onion after harvest and storage, with fluorescent, blue, red and ultra violet light influenced the quercetin and quercetin glucosides profile. In a peeled onion, all the light treatments elevated quercetin content in bulb. Among them, particularly fluorescent light effect was more eminent which stimulates the maximum synthesis of quercetin in onion. In case of whole onion bulb, skin and pulp showed different responses to light treatment, respectively. The pulp had the highest quercetin glucosides under blue light, whereas the lowest under fluorescent light. Onion skin showed nearly opposite pattern as compared to the pulp. In particular, light treatment proved to be a better way to increase the level of quercetin content in onions which might be utilized for industrial production of bioactive compounds from onion and onion waste products. PMID:26150744

  8. Water-soluble constituents of caraway: aromatic compound, aromatic compound glucoside and glucides.

    PubMed

    Matsumura, Tetsuko; Ishikawa, Toru; Kitajima, Junichi

    2002-10-01

    From the water-soluble portion of the methanolic extract of caraway (fruit of Carum carvi L.), an aromatic compound, an aromatic compound glucoside and a glucide were isolated together with 16 known compounds. Their structures were clarified as 2-methoxy-2-(4'-hydroxyphenyl)ethanol, junipediol A 2-O-beta-D-glucopyranoside and L-fucitol, respectively.

  9. Simultaneous extraction of bioactive limonoid aglycones and glucoside from Citrus aurantium L. using hydrotropy.

    PubMed

    Dandekar, Deepak V; Jayaprakasha, Guddadarangavvanahally K; Patil, Bhimanagouda S

    2008-01-01

    Citrus limonoids were demonstrated to possess potential biological activities in reducing the risk of certain diseases. Limonoids are present in citrus fruits in the form of aglycones and glucosides. At present, limonoid aglycones and limonoid glucosides are extracted in multiple steps using different solvents. In order to understand their potential bioactivity, it may be beneficial to isolate and purify these compounds using environment friendly methods. A new method of extraction and purification of limonoids was established using a hydrotrope polystyrene adsorbent resin. Extraction of aglycones and glucosides was achieved in a single step, using an aqueous solution of sodium cumene sulphonate (Na-CuS). Sour orange (Citrus aurantium L.) seed powder was extracted with 2 M Na-CuS solution at 45 degrees C for 6 h. The filtered extract was diluted with water and loaded on an SP 700 adsorbent column. The column was washed with distilled water to remove the hydrotrope and then eluted using water and methanol in different compositions to obtain three compounds. The structures of the isolated compounds were confirmed by NMR spectroscopy as deacetyl nomilinic acid glucoside (DNAG), deacetyl nomilin (DAN) and limonin (LIM).

  10. Analysis of Ginkgo biloba for the presence of ginkgotoxin and ginkgotoxin 5'-glucoside.

    PubMed

    Scott, P M; Lau, B P; Lawrence, G A; Lewis, D A

    2000-01-01

    Hot water extracts of Ginkgo biloba seeds were analyzed for the presence of ginkgotoxin (4'-O-methylpyridoxine) by reversed-phase liquid chromatography (LC) using methanol-0.05M KH2PO4 (1 + 9, v/v) adjusted to pH 3 as mobile phase. Detection was by fluorescence (excitation 280 nm, emission 370 nm). A straight line calibration curve was obtained for the 10-100 ng injected. After addition of beta-glucosidase (37 degrees C/h), an earlier eluting peak disappeared and the ginkgotoxin peak increased. The identity of the ginkgotoxin was confirmed by LC/MS and LC/MS/MS. LC/MS/MS also confirmed the 5'-glucoside by comparison with the 3-glucoside. This is the first identification of a glucoside of ginkgotoxin in Ginkgo biloba. An unknown compound of MW 267 also observed in the Ginkgo biloba seed extract was shown not to be 3,5'-diacetylginkgotoxin by its different LC retention time. Extraction of ground Ginkgo biloba seeds with boiling water in a Soxhlet for 2 x 2 h yielded a total of 179 microg/g of free ginkgotoxin. The concentration in powder from Ginkgo biloba capsules was several times lower than this (17-64 microg/g) in 3 samples but higher in another (457 microg/g). Canned ginkgo seeds (white nuts) contained no detectable free ginkgotoxin but the glucoside was present. Different extraction times were studied: 0.5 h gave only 52 microg/g free ginkgotoxin in the ginkgo seeds. However, boiling an extract for 4 h showed about 15% loss of ginkgotoxin and its glucoside.

  11. Quercetin from shallots (Allium cepa L. var. aggregatum) is more bioavailable than its glucosides.

    PubMed

    Wiczkowski, Wieslaw; Romaszko, Jerzy; Bucinski, Adam; Szawara-Nowak, Dorota; Honke, Joanna; Zielinski, Henryk; Piskula, Mariusz K

    2008-05-01

    The lipophilic character of quercetin suggests that it can cross enterocyte membranes via simple diffusion. Therefore, it should be more bioavailable than its glucosides, which require preliminary hydrolysis or active transport for absorption. However, the published human studies show that quercetin is less bioavailable than its glucosides. Assuming that low bioavailability of quercetin aglycone provided to humans as a pure substance is the result of its low solubility in the digestive tract, we studied its bioavailability from dietary sources in which quercetin was dispersed in the food matrix. In a randomized crossover study, 9 volunteers took a single dose of either shallot flesh (99.2% quercetin glucosides and 0.8% quercetin aglycone) or dry shallot skin (83.3% quercetin aglycone and 16.7% quercetin glucosides), providing 1.4 mg quercetin per kg of body weight. Blood samples were collected before and after consumption of shallot preparations. Plasma quercetin was measured on HPLC with electrochemical detection after plasma enzymatic treatment. The maximum plasma quercetin concentration of 1.02 +/- 0.13 micromol/L was reached at 2.33 +/- 0.50 h after shallot flesh consumption compared with 3.95 +/- 0.62 micromol/L at 2.78 +/- 0.15 h after dry skin consumption. The area under the concentration-time curve after dry skin consumption was 47.23 +/- 7.53 micromol x h(-1) x L(-1) and was significantly higher than that after shallot flesh intake (22.23 +/- 2.32 micromol x h(-1) x L(-1)). When provided along with dietary sources, quercetin aglycone is more bioavailable than its glucosides in humans. Results point to the food matrix as a key factor.

  12. Potassium Hexacyanoferrate (III)-Catalyzed Dimerization of Hydroxystilbene: Biomimetic Synthesis of Indane Stilbene Dimers.

    PubMed

    Xie, Jing-Shan; Wen, Jin; Wang, Xian-Fen; Zhang, Jian-Qiao; Zhang, Ji-Fa; Kang, Yu-Long; Hui, You-Wei; Zheng, Wen-Sheng; Yao, Chun-Suo

    2015-12-18

    Using potassium hexacyanoferrate (III)-sodium acetate as oxidant, the oxidative coupling reaction of isorhapontigenin and resveratrol in aqueous acetone resulted in the isolation of three new indane dimers 4, 6, and 7, together with six known stilbene dimers. Indane dimer 5 was obtained for the first time by direct transformation from isorhapontigenin. The structures and relative configurations of the dimers were elucidated using spectral analysis, and their possible formation mechanisms were discussed. The results indicate that this reaction could be used as a convenient method for the semi-synthesis of indane dimers because of the mild conditions and simple reaction products.

  13. Electronic transitions of palladium dimer

    SciTech Connect

    Qian, Yue; Ng, Y. W.; Chen, Zhihua; Cheung, A. S.-C.

    2013-11-21

    The laser induced fluorescence spectrum of palladium dimer (Pd{sub 2}) in the visible region between 480 and 700 nm has been observed and analyzed. The gas-phase Pd{sub 2} molecule was produced by laser ablation of palladium metal rod. Eleven vibrational bands were observed and assigned to the [17.1] {sup 3}II{sub g} - X{sup 3}Σ{sub u}{sup +} transition system. The bond length (r{sub o}) and vibrational frequency (ΔG{sub 1/2}) of the ground X{sup 3}Σ{sub u}{sup +} state were determined to be 2.47(4) Å and 211.4(5) cm{sup −1}, respectively. A molecular orbital energy level diagram was used to understand the observed ground and excited electronic states. This is the first gas-phase experimental investigation of the electronic transitions of Pd{sub 2}.

  14. Structural characterization of dimeric murine aminoacylase III.

    PubMed

    Ryazantsev, Sergey; Abuladze, Natalia; Newman, Debra; Bondar, Galyna; Kurtz, Ira; Pushkin, Alexander

    2007-05-01

    Aminoacylase III (AAIII) plays an important role in deacetylation of acetylated amino acids and N-acetylated S-cysteine conjugates of halogenated alkenes and alkanes. AAIII, recently cloned from mouse kidney and partially characterized, is a mixture of tetramers and dimers. In the present work, AAIII dimers were purified and shown to be enzymatically active. Limited trypsinolysis showed two domains of approximately 9 and 25 kDa. The three-dimensional structure of the dimer was studied by electron microscopy of negative stained samples and by single-particle reconstruction. A 16A resolution model of the AAIII dimer was created. It has an unusual, cage-like, structure. A realistic AAIII tetramer model was built from two dimers.

  15. Dimer statistics on the Klein bottle

    NASA Astrophysics Data System (ADS)

    Lu, Fuliang; Zhang, Lianzhu; Lin, Fenggen

    2011-06-01

    The problem of enumerating close-packed dimers, or perfect matchings, on a quadratic lattice embedded on the Klein bottle is considered. Thomassen [C. Thomassen, Tilings of the torus and the Klein Bottle and vertex-transitive graphs on a fixed surface, Trans. Amer. Math. Soc. 323(2) (1991) 605-635] characterized that there are six quadrilateral lattices embedded on the Klein bottle. Lu and Wu [W. T. Lu and F. Y. Wu, Close-packed dimers on nonorientable surfaces, Phys. Lett. A 293 (2002) 235-246] had obtained a expression for the number of close-packed dimers on one of them. In this paper we investigate four other embeddings and obtain explicit expressions of the numbers of close-packed dimers and free energy per dimer by enumerating Pfaffians.

  16. Statistical transmutation in doped quantum dimer models.

    PubMed

    Lamas, C A; Ralko, A; Cabra, D C; Poilblanc, D; Pujol, P

    2012-07-06

    We prove a "statistical transmutation" symmetry of doped quantum dimer models on the square, triangular, and kagome lattices: the energy spectrum is invariant under a simultaneous change of statistics (i.e., bosonic into fermionic or vice versa) of the holes and of the signs of all the dimer resonance loops. This exact transformation enables us to define the duality equivalence between doped quantum dimer Hamiltonians and provides the analytic framework to analyze dynamical statistical transmutations. We investigate numerically the doping of the triangular quantum dimer model with special focus on the topological Z(2) dimer liquid. Doping leads to four (instead of two for the square lattice) inequivalent families of Hamiltonians. Competition between phase separation, superfluidity, supersolidity, and fermionic phases is investigated in the four families.

  17. Cyanogenic glucosides in the biological warfare between plants and insects: the Burnet moth-Birdsfoot trefoil model system.

    PubMed

    Zagrobelny, Mika; Møller, Birger Lindberg

    2011-09-01

    Cyanogenic glucosides are important components of plant defense against generalist herbivores due to their bitter taste and the release of toxic hydrogen cyanide upon tissue disruption. Some specialized herbivores, especially insects, preferentially feed on cyanogenic plants. Such herbivores have acquired the ability to metabolize cyanogenic glucosides or to sequester them for use in their own predator defense. Burnet moths (Zygaena) sequester the cyanogenic glucosides linamarin and lotaustralin from their food plants (Fabaceae) and, in parallel, are able to carry out de novo synthesis of the very same compounds. The ratio and content of cyanogenic glucosides is tightly regulated in the different stages of the Zygaena filipendulae lifecycle and the compounds play several important roles in addition to defense. The transfer of a nuptial gift of cyanogenic glucosides during mating of Zygaena has been demonstrated as well as the possible involvement of hydrogen cyanide in male assessment and nitrogen metabolism. As the capacity to de novo synthesize cyanogenic glucosides was developed independently in plants and insects, the great similarities of the pathways between the two kingdoms indicate that cyanogenic glucosides are produced according to a universal route providing recruitment of the enzymes required. Pyrosequencing of Z. filipendulae larvae de novo synthesizing cyanogenic glucosides served to provide a set of good candidate genes, and demonstrated that the genes encoding the pathway in plants and Z. filipendulae are not closely related phylogenetically. Identification of insect genes involved in the biosynthesis and turn-over of cyanogenic glucosides will provide new insights into biological warfare as a determinant of co-evolution between plants and insects.

  18. Membrane-associated Ras dimers are isoform-specific: K-Ras dimers differ from H-Ras dimers.

    PubMed

    Jang, Hyunbum; Muratcioglu, Serena; Gursoy, Attila; Keskin, Ozlem; Nussinov, Ruth

    2016-06-15

    Are the dimer structures of active Ras isoforms similar? This question is significant since Ras can activate its effectors as a monomer; however, as a dimer, it promotes Raf's activation and MAPK (mitogen-activated protein kinase) cell signalling. In the present study, we model possible catalytic domain dimer interfaces of membrane-anchored GTP-bound K-Ras4B and H-Ras, and compare their conformations. The active helical dimers formed by the allosteric lobe are isoform-specific: K-Ras4B-GTP favours the α3 and α4 interface; H-Ras-GTP favours α4 and α5. Both isoforms also populate a stable β-sheet dimer interface formed by the effector lobe; a less stable β-sandwich interface is sustained by salt bridges of the β-sheet side chains. Raf's high-affinity β-sheet interaction is promoted by the active helical interface. Collectively, Ras isoforms' dimer conformations are not uniform; instead, the isoform-specific dimers reflect the favoured interactions of the HVRs (hypervariable regions) with cell membrane microdomains, biasing the effector-binding site orientations, thus isoform binding selectivity.

  19. A novel type of highly effective nonionic gemini alkyl O-glucoside surfactants: a versatile strategy of design.

    PubMed

    Liu, Songbai; Sang, Ruocheng; Hong, Shan; Cai, Yujing; Wang, Hua

    2013-07-09

    A novel type of highly effective gemini alkyl glucosides has been rationally designed and synthesized. The gemini surfactants have been readily prepared by glycosylation of the gemini alkyl chains that are synthesized with regioselective ring-opening of ethylene glycol epoxides by the alkyl alcohols. The new gemini alkyl glucosides exhibit significantly better surface activity than the known results. Then rheological, DLS, and TEM studies have revealed the intriguing self-assembly behavior of the novel gemini surfactants. This study has proved the effectiveness of the design of gemini alkyl glucosides which is modular, extendable, and synthetically simple. The new gemini surfactants have great potential as nano carriers in drug and gene delivery.

  20. Dimer formation during UV photolysis of diclofenac.

    PubMed

    Keen, Olya S; Thurman, E Michael; Ferrer, Imma; Dotson, Aaron D; Linden, Karl G

    2013-11-01

    Dimer formation was observed during ultraviolet (UV) photolysis of the anti-inflammatory drug diclofenac, and confirmed with mass spectrometry, NMR and fluorescence analysis. The dimers were combinations of the two parent molecules or of the parent and the product of photolysis, and had visible color. Radical formation during UV exposure and dissolved oxygen photosensitized reactions played a role in dimer formation. Singlet oxygen formed via photosensitization by photolysis products of diclofenac. It reacted with diclofenac to form an epoxide which is an intermediate in some dimer formation pathways. Quantum yield of photolysis for diclofenac was 0.21±0.02 and 0.19±0.02 for UV irradiation from medium pressure and low pressure mercury vapor lamps, respectively. Band pass filter experiments revealed that the quantum yield is constant at wavelengths >200 nm. The same dimers formed in laboratory grade water when either of the two UV sources was used. Dimers did not form in wastewater effluent matrix, and diclofenac epoxide molecules may have formed bonds with organic matter rather than each other Implications for the importance of dimer formation in NOM are discussed. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Vibrationally resolved emission of thiophosgene dimer

    NASA Astrophysics Data System (ADS)

    Berrios, Eduardo; Hui, Ho Yee; Gruebele, Martin

    2010-09-01

    During a study of thiophosgene electronic spectra, Fujiwara and co-workers observed a broad electronic transition peaked at 37 000 cm -1, attributed to thiophosgene dimer. Our dispersed fluorescence spectra of a thiophosgene molecular beam excited at 36 000 cm -1 reveal several vibrational modes too low in frequency for thiophosgene. We assign them to modes of thiophosgene dimer or their combination bands. MP2 calculations support the vibrational assignment. TD-DFT, CASSCF, and coupled cluster calculations suggest that the bright electronic state of thiophosgene dimer is the B 2u symmetry fifth excited singlet state. Two additional transitions are assigned to a thiophosgene synthesis impurity, trichloromethanesulfenyl chloride.

  2. Quantum dimer model for the pseudogap metal

    PubMed Central

    Punk, Matthias; Allais, Andrea; Sachdev, Subir

    2015-01-01

    We propose a quantum dimer model for the metallic state of the hole-doped cuprates at low hole density, p. The Hilbert space is spanned by spinless, neutral, bosonic dimers and spin S=1/2, charge +e fermionic dimers. The model realizes a “fractionalized Fermi liquid” with no symmetry breaking and small hole pocket Fermi surfaces enclosing a total area determined by p. Exact diagonalization, on lattices of sizes up to 8×8, shows anisotropic quasiparticle residue around the pocket Fermi surfaces. We discuss the relationship to experiments. PMID:26195771

  3. Quantum dimer model for the pseudogap metal.

    PubMed

    Punk, Matthias; Allais, Andrea; Sachdev, Subir

    2015-08-04

    We propose a quantum dimer model for the metallic state of the hole-doped cuprates at low hole density, p. The Hilbert space is spanned by spinless, neutral, bosonic dimers and spin S = 1/2, charge +e fermionic dimers. The model realizes a "fractionalized Fermi liquid" with no symmetry breaking and small hole pocket Fermi surfaces enclosing a total area determined by p. Exact diagonalization, on lattices of sizes up to 8 × 8, shows anisotropic quasiparticle residue around the pocket Fermi surfaces. We discuss the relationship to experiments.

  4. Specificity of maltase to maltose in three different directions of reaction: hydrolytic, vanillyl alcohol glucoside and vanillyl alcohol isomaltoside synthesis.

    PubMed

    Dimitrijević, Aleksandra; Veličković, Dušan; Milosavić, Nenad; Bezbradica, Dejan

    2012-01-01

    Vanillyl alcohol glucoside is very attractive molecule due to its very powerful physiological activity. In this article, a detailed kinetic study of transglucosylation of vanillyl alcohol was performed. It was demonstrated that this reaction is very efficient (selectivity factor is 149) and occurred by a ping-pong mechanism with inhibition by glucose acceptor. At low concentration of vanillyl alcohol one additional transglucosylation product was detected. Its structure was determined to be α-isomaltoside of vanillyl alcohol, indicating that vanillyl alcohol glucoside is a product of the first transglucosylation reaction and a substrate for second, so the whole reaction mechanism was proposed. It was demonstrated that the rate of isomaltoside synthesis is two orders of magnitude smaller than glucoside synthesis, and that maltase has interestingly high K(m) value to maltose when vanillyl alcohol glucoside is second transglucosylation substrate.

  5. Genetic screening identifies cyanogenesis-deficient mutants of Lotus japonicus and reveals enzymatic specificity in hydroxynitrile glucoside metabolism.

    PubMed

    Takos, Adam; Lai, Daniela; Mikkelsen, Lisbeth; Abou Hachem, Maher; Shelton, Dale; Motawia, Mohammed Saddik; Olsen, Carl Erik; Wang, Trevor L; Martin, Cathie; Rook, Fred

    2010-05-01

    Cyanogenesis, the release of hydrogen cyanide from damaged plant tissues, involves the enzymatic degradation of amino acid-derived cyanogenic glucosides (alpha-hydroxynitrile glucosides) by specific beta-glucosidases. Release of cyanide functions as a defense mechanism against generalist herbivores. We developed a high-throughput screening method and used it to identify cyanogenesis deficient (cyd) mutants in the model legume Lotus japonicus. Mutants in both biosynthesis and catabolism of cyanogenic glucosides were isolated and classified following metabolic profiling of cyanogenic glucoside content. L. japonicus produces two cyanogenic glucosides: linamarin (derived from Val) and lotaustralin (derived from Ile). Their biosynthesis may involve the same set of enzymes for both amino acid precursors. However, in one class of mutants, accumulation of lotaustralin and linamarin was uncoupled. Catabolic mutants could be placed in two complementation groups, one of which, cyd2, encoded the beta-glucosidase BGD2. Despite the identification of nine independent cyd2 alleles, no mutants involving the gene encoding a closely related beta-glucosidase, BGD4, were identified. This indicated that BGD4 plays no role in cyanogenesis in L. japonicus in vivo. Biochemical analysis confirmed that BGD4 cannot hydrolyze linamarin or lotaustralin and in L. japonicus is specific for breakdown of related hydroxynitrile glucosides, such as rhodiocyanoside A. By contrast, BGD2 can hydrolyze both cyanogenic glucosides and rhodiocyanosides. Our genetic analysis demonstrated specificity in the catabolic pathways for hydroxynitrile glucosides and implied specificity in their biosynthetic pathways as well. In addition, it has provided important tools for elucidating and potentially modifying cyanogenesis pathways in plants.

  6. Metabolism of flavone C-glucosides and p-coumaric acid from antioxidant of bamboo leaves (AOB) in rats.

    PubMed

    Zhang, Yu; Tie, Xiaowei; Bao, Bili; Wu, Xiaoqin; Zhang, Ying

    2007-03-01

    The metabolism of flavone C-glucosides and p-coumaric acid from antioxidant of bamboo leaves (AOB) in rats is discussed systematically in the present study. Following single oral administration of AOB, p-coumaric acid was detected in plasma but not in gastrointestinal tract extracts and faeces, and the corresponding absorption pharmacokinetic curve at different time points showed a prolonged elimination phase with p-coumaric acid being detected in the kidneys and excreted as its original form (1 x 80 (sd 0 x 24) % and 1 x 90 (sd 0 x 26) % at 12 and 24 h, respectively). However, the four flavone C-glucosides orientin, homoorientin, vitexin and isovitexin were poorly absorbed in the gastrointestinal tract. More than 50 % recovery of flavone C-glucosides was determined at 12 h and faeces containing these four analytes (21 x 23 (sd 1 x 92) %) were excreted at 24 h. These data suggested that the effective time these compounds were in the colon was long enough so that they could exert their antioxidant activity and scavenge free radicals. Besides the excretion of the original forms, moieties of the flavone C-glucosides were hydrolysed by deglycosylation and the opening of the heterocyclic C ring. Some small molecules such as phloroglucinol (PG), hydrocaffeic acid (HCA) and phloretic acid (PA) were detected and identified as metabolites of the flavone C-glucosides. In the present work, we compared the metabolic fate of flavone C-glucosides to that of flavone O-glucosides in rats, and evaluated the absorption, tissue distribution and excretion of flavone C-glucosides in AOB on their metabolism for the first time.

  7. Exclusive accumulation of Z-isomers of monolignols and their glucosides in bark of Fagus grandifolia

    NASA Technical Reports Server (NTRS)

    Lewis, N. G.; Inciong, E. J.; Ohashi, H.; Towers, G. H.; Yamamoto, E.

    1988-01-01

    In addition to Z-coniferyl and Z-sinapyl alcohols, bark extracts of Fagus grandifolia also contain significant amounts of the glucosides, Z-coniferin, Z-isoconiferin (previously called faguside) and Z-syringin. The corresponding E-isomers of these glucosides do not accumulate to a detectable level. The accumulation of the Z-isomers suggests that either they are not lignin precursors or that they are reservoirs of monolignols for subsequent lignin biosynthesis; it is not possible to distinguish between these alternatives. The co-occurrence of Z-coniferin and Z-isoconiferin demonstrate that glucosylation of monolignols can occur at either the phenolic or the allylic hydroxyl groups.

  8. Hepatoprotective activity of twelve novel 7'-hydroxy lignan glucosides from Arctii Fructus.

    PubMed

    Yang, Ya-Nan; Huang, Xiao-Ying; Feng, Zi-Ming; Jiang, Jian-Shuang; Zhang, Pei-Cheng

    2014-09-17

    Twelve novel 7'-hydroxy lignan glucosides (1-12), including two benzofuran-type neolignans, two 8-O-4' neolignans, two dibenzylbutyrolactone lignans, and six tetrahydrofuranoid lignans, together with six known lignan glucosides (13-18), were isolated from the fruit of Arctium lappa L. (Asteraceae), commonly known as Arctii Fructus. Their structures were elucidated using spectroscopy (1D and 2D NMR, MS, IR, ORD, and UV) and on the basis of chemical evidence. The absolute configurations of compounds 1-12 were confirmed using rotating frame nuclear overhauser effect spectroscopy (ROESY), the circular dichroic (CD) exciton chirality method, and Rh2(OCOCF3)4-induced CD spectrum analysis. All of the isolated compounds were tested for hepatoprotective effects against D-galactosamine-induced cytotoxicity in HL-7702 hepatic cells. Compounds 1, 2, 7-12, and 17 showed significantly stronger hepatoprotective activity than the positive control bicyclol at a concentration of 1 × 10(-5) M.

  9. The chain length of lignan macromolecule from flaxseed hulls is determined by the incorporation of coumaric acid glucosides and ferulic acid glucosides.

    PubMed

    Struijs, Karin; Vincken, Jean-Paul; Doeswijk, Timo G; Voragen, Alphons G J; Gruppen, Harry

    2009-01-01

    Lignan macromolecule from flaxseed hulls is composed of secoisolariciresinol diglucoside (SDG) and herbacetin diglucoside (HDG) moieties ester-linked by 3-hydroxy-3-methylglutaric acid (HMGA), and of p-coumaric acid glucoside (CouAG) and ferulic acid glucoside (FeAG) moieties ester-linked directly to SDG. The linker molecule HMGA was found to account for 11% (w/w) of the lignan macromolecule. Based on the extinction coefficients and RP-HPLC data, it was determined that SDG contributes for 62.0% (w/w) to the lignan macromolecule, while CouAG, FeAG, and HDG contribute for 12.2, 9.0, and 5.7% (w/w), respectively. Analysis of fractions of lignan macromolecule showed that the higher the molecular mass, the higher the proportion of SDG was. An inverse relation between the molecular mass and the proportion (%) CouAG+FeAG was found. Together with the structural information of oligomers of lignan macromolecule obtained after partial saponification, it is hypothesized that the amount of CouAG+FeAG present during biosynthesis determines the chain length of lignan macromolecule. Furthermore, the chain length was estimated from a model describing lignan macromolecule based on structural and compositional data. The average chain length of the lignan macromolceule was calculated to be three SDG moieties with CouAG or FeAG at each of the terminal positions, with a variation between one and seven SDG moieties.

  10. Environment assisted energy transfer in dimer system

    SciTech Connect

    Khan, Salman; Ibrahim, M.; Khan, M.K.

    2014-02-15

    The influence of collective and multilocal environments on the energy transfer between the levels of a dimer is studied. The dynamics of energy transfer are investigated by considering coupling of collective environment with the levels of the dimer in the presence of both two individuals and mutually correlated multilocal environments. It is shown that every way of coupling we consider assists, though differently, the probability of transition between the levels of dimer. The probability of transition is strongly enhanced when the two local environments are mutually correlated. -- Highlights: • The dynamics of energy transfer between the levels of a dimer are studied. • Coupling of collective as well as individual environments are considered. • The environments are in spin star configurations. • The environment assists the energy transfer between the levels. • For correlated multilocal environments, the transition probability is almost 100%.

  11. Formation of Cystine Slipknots in Dimeric Proteins

    PubMed Central

    Sikora, Mateusz; Cieplak, Marek

    2013-01-01

    We consider mechanical stability of dimeric and monomeric proteins with the cystine knot motif. A structure based dynamical model is used to demonstrate that all dimeric and some monomeric proteins of this kind should have considerable resistance to stretching that is significantly larger than that of titin. The mechanisms of the large mechanostability are elucidated. In most cases, it originates from the induced formation of one or two cystine slipknots. Since there are four termini in a dimer, there are several ways of selecting two of them to pull by. We show that in the cystine knot systems, there is strong anisotropy in mechanostability and force patterns related to the selection. We show that the thermodynamic stability of the dimers is enhanced compared to the constituting monomers whereas machanostability is either lower or higher. PMID:23520470

  12. Generalized Fibonacci Numbers and Dimer Statistics

    NASA Astrophysics Data System (ADS)

    Lu, W. T.; Wu, F. Y.

    2003-04-01

    We establish new product identities involving the q-analogue of the Fibonacci numbers. We show that the identities lead to alternate expressions of generating functions for close-packed dimers on non-orientable surfaces.

  13. Generalized Fibonacci Numbers and Dimer Statistics

    NASA Astrophysics Data System (ADS)

    Lu, W. T.; Wu, F. Y.

    We establish new product identities involving the q-analogue of the Fibonacci numbers. We show that the identities lead to alternate expressions of generating functions for close-packed dimers on non-orientable surfaces.

  14. Purunusides A-C, alpha-glucosidase inhibitory homoisoflavone glucosides from Prunus domestica.

    PubMed

    Kosar, Shaheen; Fatima, Itrat; Mahmood, Azhar; Ahmed, Rehana; Malik, Abdul; Talib, Sumaira; Chouhdary, Muhammad Iqbal

    2009-12-01

    Purunusides A-C (1-3), new homoisoflavone glucosides together with the known compounds beta-sitosterol (4) and 6,7-methylenedioxy-8-methoxycoumarin (5) have been isolated from n-butanol and ethyl acetate soluble fractions of Prunus domestica. Their structures were assigned on the basis of spectral studies. The compounds 1-3 showed potent inhibitory activity against the enzyme alpha-glucosidase.

  15. Anaerobic transformation of quercetin-3-glucoside by bacteria from the human intestinal tract.

    PubMed

    Schneider, H; Schwiertz, A; Collins, M D; Blaut, M

    1999-01-01

    From human feces two phenotypically different types of bacteria were isolated on quercetin-3-glucoside as carbon and energy source. Isolates of one type were identified as strains of Enterococcus casseliflavus. They utilized the sugar moiety of the glycoside, but did not degrade the aglycon further. The sugar moiety (4 mM) was fermented to 5.5 +/- 2.1 mM formate, 2.1 +/- 0.7 mM acetate, 1.6 +/- 0.3 mM l-lactate, and 1.3 +/- 0.4 mM ethanol. The second type of isolate was identified as Eubacterium ramulus. This organism was capable of degrading the aromatic ring system. Growing cultures of Eubacterium ramulus converted 5 mM quercetin-3-glucoside to 1.7 +/- 0.6 mM 3,4-dihydroxyphenylacetic acid, 7.6 +/- 1.0 mM acetate, and 4.0 +/- 0.4 mM butyrate. Molecular hydrogen, 3,4-dihydroxybenzaldehyde, and ethanol were detected in small amounts. Phloroglucinol was a transient intermediate in the breakdown of quercetin-3-glucoside. Eubacterium ramulus did not grow on the aglycon quercetin or the ring-fission intermediate phloroglucinol, but cleaved the flavonoid ring system when glucose was present as a cosubstrate. The most probable number of quercetin-3-glucoside-degrading bacteria determined in nine human fecal samples was 10(7)-10(9)/g dry mass. Isolates from these experiments were all identified as Eubacterium ramulus.

  16. MATE transporters facilitate vacuolar uptake of epicatechin 3'-O-glucoside for proanthocyanidin biosynthesis in Medicago truncatula and Arabidopsis.

    PubMed

    Zhao, Jian; Dixon, Richard A

    2009-08-01

    Expression of the Arabidopsis thaliana MYB transcription factor TRANSPARENT TESTA 2 (TT2) in Medicago trunculata hairy roots induces both proanthocyanidin accumulation and the ATP-dependent vacuolar/vesicular uptake of epicatechin 3'-O-glucoside; neither process is active in control roots that do, however, possess anthocyanidin 3-O-glucoside vacuolar uptake activity. A vacuolar membrane-localized multidrug and toxic compound extrusion (MATE) transporter, Medicago MATE1, was identified at the molecular level and shown to preferentially transport epicatechin 3'-O-glucoside. Genetic evidence has implicated TT12, a tonoplastic MATE transporter from Arabidopsis, in the transport of precursors for proanthocyanidin biosynthesis in the seed coat. However, although Arabidopsis TT12 facilitates the transport of cyanidin 3-O-glucoside into membrane vesicles when expressed in yeast, there is no evidence that cyanidin 3-O-glucoside is converted to proanthocyanidins after transport into the vacuole. Here, we show that Arabidopsis TT12, like Medicago MATE1, functions to transport epicatechin 3'-O-glucoside as a precursor for proanthocyanidin biosynthesis, and Medicago MATE1 complements the seed proanthocyanidin phenotype of the Arabidopsis tt12 mutant both quantitatively and qualitatively. On the basis of biochemical properties, tissue-specific expression pattern, and genetic loss-of-function analysis, we conclude that MATE1 is an essential membrane transporter for proanthocyanidin biosynthesis in the Medicago seed coat. Implications of these findings for the assembly of oligomeric proanthocyanidins are discussed.

  17. Close-packed dimers on nonorientable surfaces

    NASA Astrophysics Data System (ADS)

    Lu, Wentao T.; Wu, F. Y.

    2002-02-01

    The problem of enumerating dimers on an M× N net embedded on nonorientable surfaces is considered. We solve both the Möbius strip and Klein bottle problems for all M and N with the aid of imaginary dimer weights. The use of imaginary weights simplifies the analysis, and as a result we obtain new compact solutions in the form of double products. The compact expressions also permit us to establish a general reciprocity theorem.

  18. Pfaffian Correlation Functions of Planar Dimer Covers

    NASA Astrophysics Data System (ADS)

    Aizenman, Michael; Valcázar, Manuel Laínz; Warzel, Simone

    2017-01-01

    The Pfaffian structure of the boundary monomer correlation functions in the dimer-covering planar graph models is rederived through a combinatorial/topological argument. These functions are then extended into a larger family of order-disorder correlation functions which are shown to exhibit Pfaffian structure throughout the bulk. Key tools involve combinatorial switching symmetries which are identified through the loop-gas representation of the double dimer model, and topological implications of planarity.

  19. Regulation of gene expression: Cryptic β-glucoside (bgl) operon of Escherichia coli as a paradigm

    PubMed Central

    Harwani, Dharmesh

    2014-01-01

    Bacteria have evolved various mechanisms to extract utilizable substrates from available resources and consequently acquire fitness advantage over competitors. One of the strategies is the exploitation of cryptic cellular functions encoded by genetic systems that are silent under laboratory conditions, such as the bgl (β-glucoside) operon of E. coli. The bgl operon of Escherichia coli, involved in the uptake and utilization of aromatic β-glucosides salicin and arbutin, is maintained in a silent state in the wild type organism by the presence of structural elements in the regulatory region. This operon can be activated by mutations that disrupt these negative elements. The fact that the silent bgl operon is retained without accumulating deleterious mutations seems paradoxical from an evolutionary view point. Although this operon appears to be silent, specific physiological conditions might be able to regulate its expression and/or the operon might be carrying out function(s) apart from the utilization of aromatic β-glucosides. This is consistent with the observations that the activated operon confers a Growth Advantage in Stationary Phase (GASP) phenotype to Bgl+ cells and exerts its regulation on at least twelve downstream target genes. PMID:25763016

  20. Occurrence of sarmentosin and other hydroxynitrile glucosides in Parnassius (papilionidae) butterflies and their food plants.

    PubMed

    Bjarnholt, Nanna; Nakonieczny, Mirosław; Kędziorski, Andrzej; Debinski, Diane M; Matter, Stephen F; Olsen, Carl Erik; Zagrobelny, Mika

    2012-05-01

    Sequestration of plant secondary metabolites is a widespread phenomenon among aposematic insects. Sarmentosin is an unsaturated γ-hydroxynitrile glucoside known from plants and some Lepidoptera. It is structurally and biosynthetically closely related to cyanogenic glucosides, which are commonly sequestered from food plants and/or de novo synthesized by lepidopteran species. Sarmentosin was found previously in Parnassius (Papilionidae) butterflies, but it was not known how the occurrence was related to food plants or whether Parnassius species could biosynthesize the compound. Here, we report on the occurrence of sarmentosin and related compounds in four different Parnassius species belonging to two different clades, as well as their known and suspected food plants. There were dramatic differences between the two clades, with P. apollo and P. smintheus from the Apollo group containing high amounts of sarmentosin, and P. clodius and P. mnemosyne from the Mnemosyne group containing low or no detectable amounts. This was reflected in the larval food plants; P. apollo and P. smintheus larvae feed on Sedum species (Crassulaceae), which all contained considerable amounts of sarmentosin, while the known food plants of the two other species, Dicentra and Corydalis (Fumariaceae), had no detectable levels of sarmentosin. All insects and plants containing sarmentosin also contained other biosynthetically related hydroxynitrile glucosides in patterns previously reported for plants, but not for insects. Not all findings could be explained by sequestration alone and we therefore hypothesize that Parnassius species are able to de novo synthesize sarmentosin.

  1. Modulation of protein tyrosine nitration and inflammatory mediators by isoprenylhydroquinone glucoside.

    PubMed

    Olmos, Ana; Giner, Rosa-María; Recio, María-Carmen; Ríos, José-Luis; Máñez, Salvador

    2007-03-01

    The nitration of tyrosine caused by peroxynitrite and other reactive nitrogen species is clearly detrimental for some physiological processes; however, its signalling role is still open to controversy. Among the natural phenolics known for their ability to oppose free tyrosine nitration, isoprenylhydroquinone glucoside is investigated due to its unusual structure, which contains a simple hydroxybenzene alkylated by a hemiterpenoid moiety. This hydroquinone was shown to be an effective inhibitor of peroxynitrite-induced protein tyrosine nitration in 3T3 fibroblasts. When tested on bovine seroalbumin nitration, however, the potency was reduced by half and the effect was almost abolished in the presence of bicarbonate. In contrast, addition of this anion had no effect on the nitrite/hydrogen peroxide/hemin system. Isoprenylhydroquinone glucoside was also active in the microM range on intra- and extracellular protein-bound tyrosine nitration by phorbol 12-myristate 13-acetate-stimulated neutrophils. The effects on nitric oxide synthase expression, interleukin-1beta and tumor necrosis factor-alpha production by lipopolysaccharide-stimulated macrophages were quite moderate. Thus, isoprenylhydroquinone glucoside is an inhibitor of protein nitration in situ, but lacks effect on the generation of either nitric oxide or inflammatory cytokines.

  2. Regulation of gene expression: cryptic β-glucoside (bgl) operon of Escherichia coli as a paradigm.

    PubMed

    Harwani, Dharmesh

    2014-01-01

    Bacteria have evolved various mechanisms to extract utilizable substrates from available resources and consequently acquire fitness advantage over competitors. One of the strategies is the exploitation of cryptic cellular functions encoded by genetic systems that are silent under laboratory conditions, such as the bgl (β-glucoside) operon of E. coli. The bgl operon of Escherichia coli, involved in the uptake and utilization of aromatic β-glucosides salicin and arbutin, is maintained in a silent state in the wild type organism by the presence of structural elements in the regulatory region. This operon can be activated by mutations that disrupt these negative elements. The fact that the silent bgl operon is retained without accumulating deleterious mutations seems paradoxical from an evolutionary view point. Although this operon appears to be silent, specific physiological conditions might be able to regulate its expression and/or the operon might be carrying out function(s) apart from the utilization of aromatic β-glucosides. This is consistent with the observations that the activated operon confers a Growth Advantage in Stationary Phase (GASP) phenotype to Bgl(+) cells and exerts its regulation on at least twelve downstream target genes.

  3. Bioconversion of piceid to piceid glucoside using amylosucrase from Alteromonas macleodii deep ecotype.

    PubMed

    Park, Hyunsu; Kim, Jieun; Park, Ji-Hae; Baek, Nam-In; Park, Cheon-Seok; Lee, Hee-Seob; Cha, Jaeho

    2012-12-01

    Resveratrol, or its glycoside form piceid, is a dietary antioxidant polyphenolic compound, found in grapes and red wine that has been shown to have protective effects against cardiovascular disease. However, very low water solubility of the compound may limit its application in the food and pharmaceutical industries. The amylosucrase (AMAS) of Alteromonas macleodii Deep ecotype was expressed in Escherichia coli and showed high glycosyltransferase activity to produce the glucosyl piceid when piceid was used as an acceptor. The conversion yield of piceid glucoside was 35.2%. Biotransformation using culture of the E. coli harboring the amas gene increased the yield up to 70.8%. The transfer product was purified by reverse phase chromatography and recycling preparative HPLC, and the molecular structure of the piceid glucoside was determined using NMR spectroscopy. The piceid glucoside was identified as glucosyl-alpha-(1-->4)-piceid. The solubility of glucosyl piceid was 5.26 and 1.14 times higher than those of resveratrol and piceid, respectively. It is anticipated that dietary intake of this compound is more effective by enhancing the bioavailability of resveratrol in the human body because of its hydrophilic properties in the intestinal fluid.

  4. Occurrence of deoxynivalenol and deoxynivalenol-3-glucoside in durum wheat from Argentina.

    PubMed

    Palacios, Sofía A; Erazo, Jessica G; Ciasca, Biancamaria; Lattanzio, Veronica M T; Reynoso, María M; Farnochi, María C; Torres, Adriana M

    2017-09-01

    The occurrence of deoxynivalenol, 3- and 15-deoxynivalenol and deoxynivalenol-3-glucoside in 84 durum wheat samples, from the Argentinean main growing area, was investigated during 2012/13 and 2013/14 using LC-MS/MS. Deoxynivalenol was found in all samples at concentrations varying between glucoside was detected in 94% of the samples at concentrations ranging from glucoside in wheat in Argentina. All the commercial cultivars transformed deoxynivalenol to its glucosylated form at conversion rates between 6 and 22%. The results obtained alert of the potential risk present in durum wheat for Argentinean consumers but also show that some of the commercial cultivars currently on used could be promising candidates for breeding programs intended to obtained Fusarium head blight resistance. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. The two-state dimer receptor model: a general model for receptor dimers.

    PubMed

    Franco, Rafael; Casadó, Vicent; Mallol, Josefa; Ferrada, Carla; Ferré, Sergi; Fuxe, Kjell; Cortés, Antoni; Ciruela, Francisco; Lluis, Carmen; Canela, Enric I

    2006-06-01

    Nonlinear Scatchard plots are often found for agonist binding to G-protein-coupled receptors. Because there is clear evidence of receptor dimerization, these nonlinear Scatchard plots can reflect cooperativity on agonist binding to the two binding sites in the dimer. According to this, the "two-state dimer receptor model" has been recently derived. In this article, the performance of the model has been analyzed in fitting data of agonist binding to A(1) adenosine receptors, which are an example of receptor displaying concave downward Scatchard plots. Analysis of agonist/antagonist competition data for dopamine D(1) receptors using the two-state dimer receptor model has also been performed. Although fitting to the two-state dimer receptor model was similar to the fitting to the "two-independent-site receptor model", the former is simpler, and a discrimination test selects the two-state dimer receptor model as the best. This model was also very robust in fitting data of estrogen binding to the estrogen receptor, for which Scatchard plots are concave upward. On the one hand, the model would predict the already demonstrated existence of estrogen receptor dimers. On the other hand, the model would predict that concave upward Scatchard plots reflect positive cooperativity, which can be neither predicted nor explained by assuming the existence of two different affinity states. In summary, the two-state dimer receptor model is good for fitting data of binding to dimeric receptors displaying either linear, concave upward, or concave downward Scatchard plots.

  6. Role of Rydberg states in the photostability of heterocyclic dimers: the case of pyrazole dimer.

    PubMed

    Zilberg, Shmuel; Haas, Yehuda

    2012-11-26

    A new route for the nonradiative decay of photoexcited, H-bonded, nitrogen-containing, heterocyclic dimers is offered and exemplified by a study of the pyrazole dimer. In some of these systems the N(3s) Rydberg state is the lowest excited singlet state. This state is formed by direct light absorption or by nonradiative transition from the allowed ππ* state. An isomer of this Rydberg state is formed by H atom transfer to the other component of the dimer. The newly formed H-bonded radical pair is composed of two radicals (a H-adduct of pyrazole, a heterocyclic analogue of the NH(4) radical) and the pyrazolium π-radical. It is calculated to have a shallow local minimum and is the lowest point on the PES of the H-pyrazole/pyrazolium radical pair. This species can cross back to the ground state of the original dimer through a relatively small energy gap and compete with the H-atom loss channel, known for the monomer. In both Rydberg dimers, an electron occupies a Rydberg orbital centered mostly on one of the two components of the dimer. This Rydberg Center Shift (RCS) mechanism, proposed earlier (Zilberg, S.; Kahan, A.; Haas, Y. Phys. Chem. Chem. Phys. 2012, 14, 8836), leads to deactivation of the electronically excited dimer while keeping it intact. It, thus, may explain the high photostability of the pyrazole dimer as well as other heterocyclic dimers.

  7. 21 CFR 176.120 - Alkyl ketene dimers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Alkyl ketene dimers. 176.120 Section 176.120 Food... Use Only as Components of Paper and Paperboard § 176.120 Alkyl ketene dimers. Alkyl ketene dimers may... section. (a) The alkyl ketene dimers are manufactured by the dehydrohalogenation of the acyl...

  8. 21 CFR 176.120 - Alkyl ketene dimers.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Alkyl ketene dimers. 176.120 Section 176.120 Food... Use Only as Components of Paper and Paperboard § 176.120 Alkyl ketene dimers. Alkyl ketene dimers may... section. (a) The alkyl ketene dimers are manufactured by the dehydrohalogenation of the acyl...

  9. Novel glyceryl glucoside is a low toxic alternative for cryopreservation agent

    SciTech Connect

    Su, Cathy; Allum, Allison J.; Aizawa, Yasushi; Kato, Takamitsu A.

    2016-08-05

    Glyceryl glucoside (GG, α-D-glucosyglycerol) is a natural glycerol derivative found in alcoholic drinks. Recently GG has been used as an alternative for glycerol in cosmetic products. However, the safety of using GG is still unclear. Currently, dimethyl sulfoxide (DMSO) and glycerol are wildly used in cryopreservation. Despite GG being a derivative of glycerol, the ability of GG in cryopreservation is still unknown. By using a system of Chinese Hamster Ovary cells (CHO), A549 cells and AG1522 cells, the study examined the cryoprotective effects of DMSO, glycerol and GG. Cytotoxic and genotoxic responses induced by the three chemicals were also investigated with CHO to determine the safety of GG for cosmetic products. Our data suggests that GG has great cryopresearvation ability in the concentration of 30%–40% (v/v). For cytotoxic studies, DMSO showed the highest cytotoxicity above 3% (v/v) in cell doubling time delay among three chemicals. For the acute cytotoxicity with trypan blue dye exclusion assay, GG showed stronger cell killing effect within 24 h above 4% (v/v). For the continuous cytotoxicity with colony formation assay for 7 days, DMSO showed significantly reduced clonogenic ability above 2%. In genotoxicity studies, CHO treated with glycerol at 2% concentration induced three times higher frequencies of sister chromatid exchange (SCE) than background levels. GG did not induce significant amounts of SCE compared to background. Micronuclei formation was equally observed in the 2% and above concentrations of glycerol and GG. Our data showed that GG has significant effects on cryopreservation compared to DMSO. Glycerol and GG have similar cytotoxicity effects to CHO, but glycerol induced genotoxic responses in the same concentration. Therefore, we conclude that GG may be a safer alternative compound to glycerol in cosmetic products and safer alternative to DMSO in cryopreservation. -- Highlights: •Glyceryl Glucoside is low cytotoxicity and genotoxicity

  10. Quantitative Analysis of Phenylpropanoid Glycerol Glucosides in Different Organs of Easter Lily (Lilium longiflorum Thunb.).

    PubMed

    Munafo, John P; Gianfagna, Thomas J

    2015-05-20

    The Easter lily (Lilium longiflorum Thunb.) is esteemed worldwide as an attractive ornamental plant, and the flower buds and bulbs are used for both culinary and medicinal purposes in many parts of the world. L. longiflorum contains significant amounts of phenylpropanoid glycerol glucosides, a group of compounds that may contribute to plant pathogen defense, ultraviolet/high-intensity visible light (UV/high light) protection, and the purported medicinal uses of lilies. To define the natural distribution of these compounds within the plant, a liquid chromatography-mass spectrometry (LC-MS) method performed in selected ion monitoring (SIM) mode was employed for the quantitative analysis of five phenylpropanoid glycerol glucosides, namely, (2S)-1-O-caffeoyl-2-O-β-D-glucopyranosylglycerol, 1; (2R)-1-O-β-D-glucopyranosyl-2-O-p-coumaroylglycerol, 2; (2S)-1-O-p-coumaroyl-2-O-β-D-glucopyranosylglycerol, 3; (2S)-1-O-caffeoyl-2-O-β-D-glucopyranosyl-3-O-acetylglycerol, 4; and (2S)-1-O-p-coumaroyl-2-O-β-D-glucopyranosyl-3-O-acetylglycerol, 5, in the different organs of L. longiflorum. The p-coumaroyl-based 3 and its acetylated derivative 5 were determined to be the most abundant of the phenylpropanoid glycerol glucosides found in Easter lily bulbs, at 776.3 ± 8.4 and 650.7 ± 32.6 μg/g dry weight, respectively. The acetylated p-coumaroyl- and caffeoyl-based derivatives, 5 and 4, accumulated to the highest concentration in the closed flower buds, at 4925.2 ± 512.8 and 3216.8 ± 406.4 μg/g dry weight, respectively. Compound 4, followed by 5 and 1, proved to be the most abundant in the mature flowers, occurring at 6006.2 ± 625.8, 2160.3 ± 556.5, and 1535.8 ± 174.1 μg/g dry weight, respectively. Total concentrations of the phenylpropanoid glycerol glucosides were 10-100-fold higher in the above-ground plant organs as compared to the bulbs and fleshy roots. Two of the five compounds, 1 and 2, were identified in L. longiflorum for the first time. The quantitative

  11. Cassava Plants with a Depleted Cyanogenic Glucoside Content in Leaves and Tubers. Distribution of Cyanogenic Glucosides, Their Site of Synthesis and Transport, and Blockage of the Biosynthesis by RNA Interference Technology1

    PubMed Central

    Jørgensen, Kirsten; Bak, Søren; Busk, Peter Kamp; Sørensen, Charlotte; Olsen, Carl Erik; Puonti-Kaerlas, Johanna; Møller, Birger Lindberg

    2005-01-01

    Transgenic cassava (Manihot esculenta Crantz, cv MCol22) plants with a 92% reduction in cyanogenic glucoside content in tubers and acyanogenic (<1% of wild type) leaves were obtained by RNA interference to block expression of CYP79D1 and CYP79D2, the two paralogous genes encoding the first committed enzymes in linamarin and lotaustralin synthesis. About 180 independent lines with acyanogenic (<1% of wild type) leaves were obtained. Only a few of these were depleted with respect to cyanogenic glucoside content in tubers. In agreement with this observation, girdling experiments demonstrated that cyanogenic glucosides are synthesized in the shoot apex and transported to the root, resulting in a negative concentration gradient basipetal in the plant with the concentration of cyanogenic glucosides being highest in the shoot apex and the petiole of the first unfolded leaf. Supply of nitrogen increased the cyanogenic glucoside concentration in the shoot apex. In situ polymerase chain reaction studies demonstrated that CYP79D1 and CYP79D2 were preferentially expressed in leaf mesophyll cells positioned adjacent to the epidermis. In young petioles, preferential expression was observed in the epidermis, in the two first cortex cell layers, and in the endodermis together with pericycle cells and specific parenchymatic cells around the laticifers. These data demonstrate that it is possible to drastically reduce the linamarin and lotaustralin content in cassava tubers by blockage of cyanogenic glucoside synthesis in leaves and petioles. The reduced flux to the roots of reduced nitrogen in the form of cyanogenic glucosides did not prevent tuber formation. PMID:16126856

  12. Novel Covalently Linked Insulin Dimer Engineered to Investigate the Function of Insulin Dimerization

    PubMed Central

    Vinther, Tine N.; Norrman, Mathias; Strauss, Holger M.; Huus, Kasper; Schlein, Morten; Pedersen, Thomas Å.; Kjeldsen, Thomas; Jensen, Knud J.; Hubálek, František

    2012-01-01

    An ingenious system evolved to facilitate insulin binding to the insulin receptor as a monomer and at the same time ensure sufficient stability of insulin during storage. Insulin dimer is the cornerstone of this system. Insulin dimer is relatively weak, which ensures dissociation into monomers in the circulation, and it is stabilized by hexamer formation in the presence of zinc ions during storage in the pancreatic β-cell. Due to the transient nature of insulin dimer, direct investigation of this important form is inherently difficult. To address the relationship between insulin oligomerization and insulin stability and function, we engineered a covalently linked insulin dimer in which two monomers were linked by a disulfide bond. The structure of this covalent dimer was identical to the self-association dimer of human insulin. Importantly, this covalent dimer was capable of further oligomerization to form the structural equivalent of the classical hexamer. The covalently linked dimer neither bound to the insulin receptor, nor induced a metabolic response in vitro. However, it was extremely thermodynamically stable and did not form amyloid fibrils when subjected to mechanical stress, underlining the importance of oligomerization for insulin stability. PMID:22363506

  13. Quercetin and cyanidin-3-glucoside protect against photooxidation and photodegradation of A2E in retinal pigment epithelial cells.

    PubMed

    Wang, Yong; Kim, Hye Jin; Sparrow, Janet R

    2017-07-01

    A family of photoreactive retinaldehyde-derived molecules accumulate in retinal pigment epithelial cells with age; this accumulation is implicated in some retinal diseases. One of these compounds is the diretinal fluorophore A2E. Here we compared polyphenols for their ability to suppress the photooxidation and photodegradation of A2E. In cells that had accumulated A2E and were irradiated with short-wavelength light, quercetin, cyanidin-3-glucoside, ferulic acid and chlorogenic acid diminished cellular levels of reactive oxygen species, but only quercetin and cyanidin-3-glucoside promoted cell viability. By chromatographic quantitation, quercetin and cyanidin-3-glucoside reduced the consumption of A2E by photooxidation in both cell- and cell-free assays. With ultra-high performance liquid chromatography-mass spectrometry, quercetin and cyanidin-3-glucoside also inhibited the formation of photooxidized-A2E species. While photodegradation of A2E is known to result in the release of reactive carbonyls, we demonstrated that quercetin and cyanidin-3-glucoside decreased the formation of methylglyoxal adducts in the cells, and reduced the expression of mRNA encoding receptor for advanced glycation end products. These polyphenols also protected glutathione from reaction with photooxidized A2E. In rod outer segments incubated with all-trans-retinal to generate bisretinoid, followed by irradiation, quercetin and cyanidin-3-glucoside reduced release of the lipid peroxidation product 4-hydroxynonenal. In conclusion, quercetin and cyanidin-3-glucoside can guard against photooxidative processes in retina. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Malonylglucoside conjugates of isoflavones are much less bioavailable compared with unconjugated β-glucosidic forms in rats.

    PubMed

    Yerramsetty, Vamsidhar; Gallaher, Daniel D; Ismail, Baraem

    2014-05-01

    Despite considerable interest in the physiologic effects of isoflavones, the in vivo bioavailability of the most common isoflavone forms, malonylglucoside conjugates, has not been determined. Differences in the bioavailability of malonylglucosides compared with the nonconjugated β-glucoside forms may explain the inconsistent findings regarding the physiologic effects of isoflavones. Therefore, our objective was to determine the effect of malonyl- conjugation on isoflavone bioavailability in an animal model. Malonylgenistin and malonyldaidzin, and their corresponding nonconjugated glucosides, were extracted from soy grits and purified using liquid chromatography. Purity of the isolated forms was confirmed by nuclear magnetic resonance analysis. Male rats were gavaged with malonylgenistin, genistin, malonyldaidzin, or daidzin at a dose of 100 μmol/kg body weight. Blood and urine samples were collected at time intervals ranging from 0 to 48 h. Isoflavone metabolites in plasma and urine were determined using stable isotope dilution-liquid chromatography/mass spectrometry. Comparisons of pharmacokinetic variables were made between nonconjugated and conjugated glucosides and over time of plasma collection. The areas under the time-concentration curve of the metabolites in the plasma obtained after the administration of nonconjugated β-glucosides were 1 to 6 times higher than those of their respective malonylglucosides (P ≤ 0.05). Additionally, maximum plasma concentration and urinary excretion of isoflavone metabolites were significantly higher (1-9 times; P ≤ 0.05) after the administration of nonconjugated β-glucosides. To our knowledge, these results demonstrated, for the first time, that nonconjugated β-glucosides are relatively more bioavailable than their respective malonylglucosides. These differences in the bioavailability of conjugated and nonconjugated β-glucosides should be considered in future studies focused on the bioactivity of isoflavones.

  15. Linking in domain-swapped protein dimers

    PubMed Central

    Baiesi, Marco; Orlandini, Enzo; Trovato, Antonio; Seno, Flavio

    2016-01-01

    The presence of knots has been observed in a small fraction of single-domain proteins and related to their thermodynamic and kinetic properties. The exchanging of identical structural elements, typical of domain-swapped proteins, makes such dimers suitable candidates to validate the possibility that mutual entanglement between chains may play a similar role for protein complexes. We suggest that such entanglement is captured by the linking number. This represents, for two closed curves, the number of times that each curve winds around the other. We show that closing the curves is not necessary, as a novel parameter G′, termed Gaussian entanglement, is strongly correlated with the linking number. Based on 110 non redundant domain-swapped dimers, our analysis evidences a high fraction of chains with a significant intertwining, that is with |G′| > 1. We report that Nature promotes configurations with negative mutual entanglement and surprisingly, it seems to suppress intertwining in long protein dimers. Supported by numerical simulations of dimer dissociation, our results provide a novel topology-based classification of protein-swapped dimers together with some preliminary evidence of its impact on their physical and biological properties. PMID:27659606

  16. A dimeric state for PRC2

    PubMed Central

    Davidovich, Chen; Goodrich, Karen J.; Gooding, Anne R.; Cech, Thomas R.

    2014-01-01

    Polycomb repressive complex-2 (PRC2) is a histone methyltransferase required for epigenetic silencing during development and cancer. Long non-coding RNAs (lncRNAs) can recruit PRC2 to chromatin. Previous studies identified PRC2 subunits in a complex with the apparent molecular weight of a dimer, which might be accounted for by the incorporation of additional protein subunits or RNA rather than PRC2 dimerization. Here we show that reconstituted human PRC2 is in fact a dimer, using multiple independent approaches including analytical size exclusion chromatography (SEC), SEC combined with multi-angle light scattering and co-immunoprecipitation of differentially tagged subunits. Even though it contains at least two RNA-binding subunits, each PRC2 dimer binds only one RNA molecule. Yet, multiple PRC2 dimers bind a single RNA molecule cooperatively. These observations suggest a model in which the first RNA binding event promotes the recruitment of multiple PRC2 complexes to chromatin, thereby nucleating repression. PMID:24992961

  17. The diamagnetic susceptibility of the tubulin dimer.

    PubMed

    Bras, Wim; Torbet, James; Diakun, Gregory P; Rikken, Geert L J A; Diaz, J Fernando

    2014-01-01

    An approximate value of the diamagnetic anisotropy of the tubulin dimer, Δχ dimer, has been determined assuming axial symmetry and that only the α -helices and β -sheets contribute to the anisotropy. Two approaches have been utilized: (a) using the value for the Δχ α for an α -helical peptide bond given by Pauling (1979) and (b) using the previously determined anisotropy of fibrinogen as a calibration standard. The Δχ dimer ≈ 4 × 10(-27) JT(-2) obtained from these measurements are similar to within 20%. Although Cotton-Mouton measurements alone cannot be used to estimate Δχ directly, the value we measured, CMdimer = (1.41 ± 0.03) × 10(-8) T(-2)cm(2)mg(-1), is consistent with the above estimate for Δχ dimer. The method utilized for the determination of the tubulin dimer diamagnetic susceptibility is applicable to other proteins and macromolecular assemblies as well.

  18. Multiply charged monopoles in cubic dimer model

    NASA Astrophysics Data System (ADS)

    Ganesh Jaya, Sreejith; Powell, Stephen

    2015-03-01

    The classical cubic dimer model is a 3D statistical mechanical system whose degrees of freedom are dimers that occupy the edges between nearest neighbour vertices of a cubic lattice. Dimer occupancies are subject to the local constraint that every vertex is associated with exactly one dimer. In the presence of an aligning interaction, it is known that the system exhibits an unconventional continuous thermal phase transition from a symmetry broken columnar phase to a Coulomb-phase. The transition is in the NCCP1 universality class, which also describes the Neel-VBS transition in the JQ model and the S =1/2 Heisenberg model with suppression of hedgehog defects. Using Monte-Carlo simulations of a pair of defects in a background of fluctuating dimers, we calculate the scaling exponents for fugacities of monopole defects of charge Q = 2 and 3 at this critical point. Our estimates suggest that Q = 3 monopoles are relevant and could therefore drive the JQ model away from the NCCP1 critical point on a hexagonal lattice.

  19. Improvement of Aptamer Affinity by Dimerization

    PubMed Central

    Hasegawa, Hijiri; Taira, Ken-ichi; Sode, Koji; Ikebukuro, Kazunori

    2008-01-01

    To increase the affinities of aptamers for their targets, we designed an aptamer dimer for thrombin and VEGF. This design is based on the avidity of the antibody, which enables the aptamer to connect easily since it is a single-strand nucleic acid. In this study, we connected a 15-mer thrombin-binding aptamer with a 29-mer thrombin-binding aptamer. Each aptamer recognizes a different part of the thrombin molecule, and the aptamer dimer has a Kd value which is 1/10 of that of the monomers from which it is composed. Also, the designed aptamer dimer has higher inhibitory activity than the reported (15-mer) thrombin-inhibiting aptamer. Additionally, we connected together two identical aptamers against vascular endothelial growth factor (VEGF165), which is a homodimeric protein. As in the case of the anti-thrombin aptamer, the dimeric anti-VEGF aptamer had a much lower Kd value than that of the monomer. This study demonstrated that the dimerization of aptamers effectively improves the affinities of those aptamers for their targets. PMID:27879754

  20. Eigenstate thermalization hypothesis in quantum dimer models

    NASA Astrophysics Data System (ADS)

    Lan, Zhihao; Powell, Stephen

    2017-09-01

    We use exact diagonalization to study the eigenstate thermalization hypothesis (ETH) in the quantum dimer model on the square and triangular lattices. Due to the nonergodicity of the local plaquette-flip dynamics, the Hilbert space, which consists of highly constrained close-packed dimer configurations, splits into sectors characterized by topological invariants. We show that this has important consequences for ETH: We find that ETH is clearly satisfied only when each topological sector is treated separately, and only for moderate ratios of the potential and kinetic terms in the Hamiltonian. By contrast, when the spectrum is treated as a whole, ETH breaks down on the square lattice and, apparently, also on the triangular lattice. These results demonstrate that quantum dimer models have interesting thermalization dynamics.

  1. Structure of the human dimeric ATM kinase

    PubMed Central

    Lau, Wilson C. Y.; Li, Yinyin; Liu, Zhe; Gao, Yuanzhu; Zhang, Qinfen; Huen, Michael S. Y.

    2016-01-01

    ABSTRACT DNA-double strand breaks activate the serine/threonine protein kinase ataxia-telangiectasia mutated (ATM) to initiate DNA damage signal transduction. This activation process involves autophosphorylation and dissociation of inert ATM dimers into monomers that are catalytically active. Using single-particle electron microscopy (EM), we determined the structure of dimeric ATM in its resting state. The EM map could accommodate the crystal structure of the N-terminal truncated mammalian target of rapamycin (mTOR), a closely related enzyme of the phosphatidylinositol 3-kinase-related protein kinase (PIKK) family, allowing for the localization of the N- and the C-terminal regions of ATM. In the dimeric structure, the actives sites are buried, restricting the access of the substrates to these sites. The unanticipated domain organization of ATM provides a basis for understanding its mechanism of inhibition. PMID:27097373

  2. Slab photonic crystals with dimer colloid bases

    SciTech Connect

    Riley, Erin K.; Liddell Watson, Chekesha M.

    2014-06-14

    The photonic band gap properties for centered rectangular monolayers of asymmetric dimers are reported. Colloids in suspension have been organized into the phase under confinement. The theoretical model is inspired by the range of asymmetric dimers synthesized via seeded emulsion polymerization and explores, in particular, the band structures as a function of degree of lobe symmetry and degree of lobe fusion. These parameters are varied incrementally from spheres to lobe-tangent dimers over morphologies yielding physically realizable particles. The work addresses the relative scarcity of theoretical studies on photonic crystal slabs with vertical variation that is consistent with colloidal self-assembly. Odd, even and polarization independent gaps in the guided modes are determined for direct slab structures. A wide range of lobe symmetry and degree of lobe fusion combinations having Brillouin zones with moderate to high isotropy support gaps between odd mode band indices 3-4 and even mode band indices 1-2 and 2-3.

  3. Partition-DFT on the water dimer.

    PubMed

    Gómez, Sara; Nafziger, Jonathan; Restrepo, Albeiro; Wasserman, Adam

    2017-02-21

    As is well known, the ground-state symmetry group of the water dimer switches from its equilibrium Cs-character to C2h-character as the distance between the two oxygen atoms of the dimer decreases below RO-O∼2.5 Å. For a range of RO-O between 1 and 5 Å, and for both symmetries, we apply Partition Density Functional Theory (PDFT) to find the unique monomer densities that sum to the correct dimer densities while minimizing the sum of the monomer energies. We calculate the work involved in deforming the isolated monomer densities and find that it is slightly larger for the Cs geometry for all RO-O. We discuss how the PDFT densities and the corresponding partition potentials support the orbital-interaction picture of hydrogen-bond formation.

  4. Structure of Active, Dimeric Human Telomerase

    PubMed Central

    Sauerwald, Anselm; Sandin, Sara; Cristofari, Gaël; Scheres, Sjors H.W.; Lingner, Joachim; Rhodes, Daniela

    2013-01-01

    Telomerase contains a large RNA subunit TER and a protein catalytic subunit TERT. Whether telomerase functions as monomer or dimer has been a matter of debate. Here we report biochemical and labeling data that show that in vivo assembled human telomerase contains two TERT subunits and binds two telomeric DNA substrates. Importantly, catalytic activity requires both TERT active sites to be functional, demonstrating that human telomerase functions as a dimer. We also present the three-dimensional structure of active, full-length human telomerase dimer, determined by single-particle electron microscopy in negative stain. Telomerase has a bilobal architecture, with the two monomers linked by a flexible interface. The monomer reconstruction at 23Å resolution, and fitting of the atomic structure of the beetle TERT subunit reveals the spatial relationship between RNA and protein subunits, providing insights into the telomerase architecture. PMID:23474713

  5. Chemical Synthesis of Deoxynivalenol-3-β-d-[(13)C₆]-glucoside and Application in Stable Isotope Dilution Assays.

    PubMed

    Habler, Katharina; Frank, Oliver; Rychlik, Michael

    2016-06-27

    Modified mycotoxins have been gaining importance in recent years and present a certain challenge in LC-MS/MS analysis. Due to the previous lack of a labeled isotopologue of the modified mycotoxin deoxynivalenol-3-glucoside, in our study we synthesized the first (13)C-labeled internal standard. Therefore, we used the Königs-Knorr method to synthesize deoxynivalenol-3-β-d-[(13)C₆]-glucoside originated from unlabeled deoxynivalenol and [(13)C₆]-labeled glucose. Using the synthesized isotopically-labeled standard deoxynivalenol-3-β-d-[(13)C₆]-glucoside and the purchased labeled standard [(13)C15]-deoxynivalenol, a stable isotope dilution LC-MS/MS method was firstly developed for deoxynivalenol-3-glucoside and deoxynivalenol in beer. The preparation and purification of beer samples was based on a solid phase extraction. The validation data of the newly developed method gave satisfying results. Intra- and interday precision studies revealed relative standard deviations below 0.5% and 7%, respectively. The recoveries ranged for both analytes between 97% and 112%. The stable isotope dilution assay was applied to various beer samples from four different countries. In summary, deoxynivalenol-3-glucoside and deoxynivalenol mostly appeared together in varying molar ratios but were quantified in rather low contents in the investigated beers.

  6. Integrable oscillator type and Schrödinger type dimers

    NASA Astrophysics Data System (ADS)

    Khare, Avinash; Saxena, Avadh

    2017-02-01

    A PT-symmetric dimer is a two-site nonlinear oscillator dimer or a two-site nonlinear Schrödinger dimer where one site loses and the other site gains energy at the same rate. We present a wide class of integrable oscillator type dimers whose Hamiltonian is of arbitrary even order. Further, we also present a wide class of integrable nonlinear Schrödinger type dimers where again the Hamiltonian is of arbitrary even order. Finally, we consider a recently discussed complex dimer model and point out a few integrable cases in that model.

  7. Graded-index optical dimer formed by optical force.

    PubMed

    Akbarzadeh, Alireza; Koschny, Thomas; Kafesaki, Maria; Economou, Eleftherios N; Soukoulis, Costas M

    2016-05-30

    We propose an optical dimer formed from two spherical lenses bound by the pressure that light exerts on matter. With the help of the method of force tracing, we find the required graded-index profiles of the lenses for the existence of the dimer. We study the dynamics of the opto-mechanical interaction of lenses under the illumination of collimated light beams and quantitatively validate the performance of proposed dimer. We also examine the stability of dimer due to the lateral misalignments and we show how restoring forces bring the dimer into lateral equilibrium. The dimer can be employed in various practical applications such as optical manipulation, sensing and imaging.

  8. Rubidium dimer destruction by a diode laser

    SciTech Connect

    Ban, T.; Aumiler, D.; Pichler, G.

    2005-02-01

    We observed rubidium dimer destruction by excitation of rubidium vapor with diode laser light tuned across the Rb D{sub 2} resonance line in a 2400 GHz tuning interval. The destruction was measured for rubidium atom concentrations in the (1-9)x10{sup 16} cm{sup -3} range, pump beam power up to 43 mW, and with a 5 Torr of the helium buffer gas. We discuss the physical mechanisms involved and specify the molecular pathways which may effectively lead to the observed dimer destruction.

  9. Water-soluble constituents of anise: new glucosides of anethole glycol and its related compounds.

    PubMed

    Ishikawa, Toru; Fujimatu, Eiko; Kitajima, Junichi

    2002-11-01

    From the water-soluble portion of the methanolic extract of the fruit of anise (Pimpinella anisum L.), which has been used as a spice and medicine since antiquity, twelve new and five known glucosides of phenylpropanoids, including four stereoisomers of anethole glycol 2'-O-beta-D-glucopyranoside and four stereoisomers of 1'-(4-hydroxyphenyl)propane-1',2'-diol 2'-O-beta-D-glucopyranoside were isolated together with anethole glycols and guaiacyl glycerol. The structures of the new compounds were clarified by spectral investigation.

  10. Interconversion of the salicylic acid signal and its glucoside in tobacco.

    PubMed

    Hennig, J; Malamy, J; Grynkiewicz, G; Indulski, J; Klessig, D F

    1993-10-01

    Salicylic acid (SA) has been proposed to play a role in the induction of pathogenesis-related (PR) proteins and systemic acquired resistance (SAR) in tobacco. Since SA is rapidly converted to salicylic acid beta-glucoside (SAG) in tobacco, we have attempted to assess the role of SAG in pathogenesis by application of chemically synthesized SAG to tobacco leaves. SAG was as active as SA in induction of PR-1 gene expression. This induction was preceded by a transient release of SA, which occurred in the extracellular spaces. The existence of a mechanism that releases SA from SAG suggests a possible role for SAG in SAR.

  11. Thalassiolin D: a new flavone O-glucoside Sulphate from the seagrass Thalassia hemprichii.

    PubMed

    Hawas, Usama W; Abou El-Kassem, Lamia T

    2017-03-29

    Thalassiolin D, a new flavone O-glucoside sulphate along with three flavonoids, two steroids, p-hydroxybenzoic acid, 4,4'-dihydroxybenzophenone and nitrogen compound, octopamine were isolated from the seagrass Thalassia hemprichii, collected from the Saudi Red Sea coast. By extensive spectroscopic analysis including 1D and 2D NMR and MS data, the structure of the new compound was elucidated as diosmetin 7-O-β-glucosyl-2″-sulphate. The new compound displayed moderately in vitro antiviral HCV protease activity with IC50 value 16 μM.

  12. Two new 5-deoxyflavan-3,4-diol glucosides from roots of Albizia chevalieri.

    PubMed

    Tchoukoua, Abdou; Kuiate Tabopda, Turibio; Uesugi, Shota; Kimura, Ken-Ichi; Kwon, Eunsang; Momma, Hiroyuki; Ngadjui, Bonaventure Tchaleu; Koseki, Takuya; Shiono, Yoshihito

    2016-11-01

    Phytochemical investigation of the roots of Albizia chevalieri led to the isolation of two new 5-deoxyflavan-3,4-diol glucosides from roots of A. chevalieri, Chevalieriflavanosides A and B. Their structures were established by 2D NMR techniques, UV, IR, CD, and mass spectrometry. Cytotoxicity of the two compounds was evaluated against acute promyelocytic leukemia HL60 cells. The antibacterial activities of 1 and 2 also were evaluated against Pseudomonas aeruginosa and Staphylococcus aureus using the agar diffusion test. Copyright © 2016 John Wiley & Sons, Ltd.

  13. A new flavonol glucoside from the aerial parts of Sida glutinosa.

    PubMed

    Das, Niranjan; Achari, Basudev; Harigaya, Yoshihiro; Dinda, Biswanath

    2011-10-01

    Phytochemical investigation on the dried aerial parts of Sida glutinosa has led to the isolation of a new flavonol glucoside, glutinoside (1), along with seven known compounds, 24(28)-dehydromakisterone A (2), 1,2,3,9-tetrahydropyrrolo[2,1-b]-quinazolin-3-amine (3), docosanoic acid, 1-triacontanol, campesterol, stigmasterol, and β-sitosterol. The structures of these compounds were elucidated by means of extensive spectroscopic techniques as well as GC/MS analysis (for sterols) and comparison with the literature data. All these seven known compounds are reported from this plant for the first time.

  14. Synthesis of 1,2-cis-2-C-branched aryl-C-glucosides via desulfurization of carbohydrate based hemithioacetals

    PubMed Central

    Mebrahtu, Fanuel M; Manana, Mandlenkosi M; Madumo, Kagiso; Sokamisa, Mokela S

    2015-01-01

    Summary 1-C and 2-C-branched carbohydrates are present as substructures in a number of biologically important compounds. Although the synthesis of such carbohydrate derivatives is extensively studied, the synthesis of 1,2-cis-2-C-branched C-, S-, and N-glycosides is less explored. In this article a synthetic strategy for the synthesis of 1,2-cis-2-C-branched-aryl-C-glucosides is reported via a hydrogenolytic desulfurization of suitably orientated carbohydrate based hemithioacetals. 1,2-cis-2-Hydroxymethyl and 2-carbaldehyde of aryl-C-glucosides have been synthesized using the current strategy in very good yields. The 2-carbaldehyde-aryl-C-glucosides have been identified as suitable substrates for the stereospecific preparation of 2,3-unsaturated-aryl-C-glycosides (Ferrier products). PMID:26124859

  15. Specific accumulation and revised structures of acridone alkaloid glucosides in the tips of transformed roots of Ruta graveolens.

    PubMed

    Kuzovkina, Inna; Al'terman, Irina; Schneider, Bernd

    2004-04-01

    The root tips of Ruta graveolens (common rue) show strong autofluorescence of acridone alkaloids, which are characteristic secondary metabolites of this plant. To study the specific distribution and accumulation of acridone alkaloids in various root segments of Ruta graveolens, root material was harvested from genetically transformed root cultures and extracts were investigated by chromatographic techniques and HPLC-(1)H NMR spectroscopy. The cells of the elongation and differentiation zones contained acridone glucosides and large amounts of acridone alkaloids, mainly rutacridone. Gravacridondiol glucoside was identified as the dominant secondary compound of the root tips and its structure revised by means of spectroscopic methods. In addition, minor acridones, including the structurally revised gravacridontriol glucoside and unknown natural products, were found in the root tip.

  16. Characterization of a β-Glucoside Operon (bgc) Prevalent in Septicemic and Uropathogenic Escherichia coli Strains▿ †

    PubMed Central

    Neelakanta, Girish; Sankar, T. Sabari; Schnetz, Karin

    2009-01-01

    Escherichia coli strains, in general, do not ferment cellobiose and aryl-β-d-glucosidic sugars, although “cryptic” β-d-glucoside systems have been characterized. Here we describe an additional cryptic operon (bgc) for the utilization of cellobiose and the aryl-β-d-glucosides arbutin and salicin at low temperature. The bgc operon was identified by the characterization of β-glucoside-positive mutants of an E. coli septicemia strain (i484) in which the well-studied bgl (aryl-β-d-glucoside) operon was deleted. These bgc* mutants appeared after 5 days of incubation on salicin indicator plates at 28°C. The bgc operon codes for proteins homologous to β-glucoside/cellobiose-specific phosphoenolpyruvate-dependent phosphotransfer system permease subunits IIB (BgcE), IIC (BgcF), and IIA (BgcI); a porin (BgcH); and a phospho-β-d-glucosidase (BgcA). Next to the bgc operon maps the divergent bgcR gene, which encodes a GntR-type transcriptional regulator. Expression of the bgc operon is dependent on the cyclic-AMP-dependent regulator protein CRP and positively controlled by BgcR. In the bgc* mutants, a single nucleotide exchange enhances the activity of the bgc promoter, rendering it BgcR independent. Typing of a representative collection of E. coli demonstrated the prevalence of bgc in strains of phylogenetic group B2, representing mainly extraintestinal pathogens, while it is rare among commensal E. coli strains. The bgc locus is also present in the closely related species Escherichia albertii. Further, bioinformatic analyses demonstrated that homologs of the bgc genes exist in the enterobacterial Klebsiella, Enterobacter, and Citrobacter spp. and also in gram-positive bacteria, indicative of horizontal gene transfer events. PMID:19233952

  17. In vitro digestion and lactase treatment influence uptake of quercetin and quercetin glucoside by the Caco-2 cell monolayer

    PubMed Central

    Boyer, Jeanelle; Brown, Dan; Liu, Rui Hai

    2005-01-01

    Background Quercetin and quercetin glycosides are widely consumed flavonoids found in many fruits and vegetables. These compounds have a wide range of potential health benefits, and understanding the bioavailability of flavonoids from foods is becoming increasingly important. Methods This study combined an in vitro digestion, a lactase treatment and the Caco-2 cell model to examine quercetin and quercetin glucoside uptake from shallot and apple homogenates. Results The in vitro digestion alone significantly decreased quercetin aglycone recovery from the shallot digestate (p < 0.05), but had no significant effect on quercetin-3-glucoside recovery (p > 0.05). Digestion increased the Caco-2 cell uptake of shallot quercetin-4'-glucoside by 2-fold when compared to the non-digested shallot. Despite the loss of quercetin from the digested shallot, the bioavailability of quercetin aglycone to the Caco-2 cells was the same in both the digested and non-digested shallot. Treatment with lactase increased quercetin recovery from the shallot digestate nearly 10-fold and decreased quercetin-4'-glucoside recovery by more than 100-fold (p < 0.05), but had no effect on quercetin recovery from apple digestates. Lactase treatment also increased shallot quercetin bioavailability to the Caco-2 cells approximately 14-fold, and decreased shallot quercetin-4'-glucoside bioavailability 23-fold (p < 0.05). These Caco-2 cells had lactase activity similar to that expressed by a lactose intolerant human. Conclusions The increase in quercetin uptake following treatment with lactase suggests that dietary supplementation with lactase may increase quercetin bioavailability in lactose intolerant humans. Combining the digestion, the lactase treatment and the Caco-2 cell culture model may provide a reliable in vitro model for examining flavonoid glucoside bioavailability from foods. PMID:15644141

  18. In vitro digestion and lactase treatment influence uptake of quercetin and quercetin glucoside by the Caco-2 cell monolayer.

    PubMed

    Boyer, Jeanelle; Brown, Dan; Liu, Rui Hai

    2005-01-11

    Quercetin and quercetin glycosides are widely consumed flavonoids found in many fruits and vegetables. These compounds have a wide range of potential health benefits, and understanding the bioavailability of flavonoids from foods is becoming increasingly important. This study combined an in vitro digestion, a lactase treatment and the Caco-2 cell model to examine quercetin and quercetin glucoside uptake from shallot and apple homogenates. The in vitro digestion alone significantly decreased quercetin aglycone recovery from the shallot digestate (p < 0.05), but had no significant effect on quercetin-3-glucoside recovery (p > 0.05). Digestion increased the Caco-2 cell uptake of shallot quercetin-4'-glucoside by 2-fold when compared to the non-digested shallot. Despite the loss of quercetin from the digested shallot, the bioavailability of quercetin aglycone to the Caco-2 cells was the same in both the digested and non-digested shallot. Treatment with lactase increased quercetin recovery from the shallot digestate nearly 10-fold and decreased quercetin-4'-glucoside recovery by more than 100-fold (p < 0.05), but had no effect on quercetin recovery from apple digestates. Lactase treatment also increased shallot quercetin bioavailability to the Caco-2 cells approximately 14-fold, and decreased shallot quercetin-4'-glucoside bioavailability 23-fold (p < 0.05). These Caco-2 cells had lactase activity similar to that expressed by a lactose intolerant human. The increase in quercetin uptake following treatment with lactase suggests that dietary supplementation with lactase may increase quercetin bioavailability in lactose intolerant humans. Combining the digestion, the lactase treatment and the Caco-2 cell culture model may provide a reliable in vitro model for examining flavonoid glucoside bioavailability from foods.

  19. Chemical behavior of methylpyranomalvidin-3-O-glucoside in aqueous solution studied by NMR and UV-visible spectroscopy.

    PubMed

    Oliveira, Joana; Petrov, Vesselin; Parola, A Jorge; Pina, Fernando; Azevedo, Joana; Teixeira, Natércia; Brás, Natércia F; Fernandes, Pedro A; Mateus, Nuno; Ramos, Maria João; de Freitas, Victor

    2011-02-17

    In the present work, the proton-transfer reactions of the methylpyranomalvidin-3-O-glucoside pigment in water with different pH values was studied by NMR and UV-visible spectroscopies. The results showed four equilibrium forms: the methylpyranomalvidin-3-O-glucoside cation, the neutral quinoidal base, the respective anionic quinoidal base, and a dianionic base unprotonated at the methyl group. According to the NMR data, it seems that for methylpyranomalvidin-3-O-glucoside besides the acid-base equilibrium between the pyranoflavylium cation and the neutral quinoidal base, a new species is formed at pD 4.88-6.10. This is corroborated by the appearance of a new set of signals in the NMR spectrum that may be assigned to the formation of hemiketal/cis-chalcone species to a small extent. The two ionization constants (pK(a1) and pK(a2)) obtained by both methods (NMR and UV-visible) for methylpyranomalvidin-3-O-glucoside are in agreement (pK(a1) = 5.17 ± 0.03; pK(a2) = 8.85 ± 0.08; and pK(a1) = 4.57 ± 0.07; pK(a2) = 8.23 ± 0.04 obtained by NMR and UV-visible spectroscopies, respectively). Moreover, the fully dianionic unprotonated form (at the methyl group) of the methylpyranomalvidin-3-O-glucoside is converted slowly into a new structure that displays a yellow color at basic pH. On the basis of the results obtained through LC-MS and NMR, the proposed structure was found to correspond to the flavonol syringetin-3-glucoside.

  20. Functional Asymmetry in Kinesin and Dynein Dimers

    PubMed Central

    Rank, Katherine C.; Rayment, Ivan

    2012-01-01

    Active transport along the microtubule lattice is a complex process that involves both the Kinesin and Dynein superfamily of motors. Transportation requires sophisticated regulation much of which occurs through the motor’s tail domain. However, a significant portion of this regulation also occurs through structural changes that arise in the motor and the microtubule upon binding. The most obvious structural change being the manifestation of asymmetry. To a first approximation in solution, kinesin dimers exhibit two-fold symmetry, and microtubules, helical symmetry. The higher symmetries of both the kinesin dimers and microtubule lattice are lost on formation of the kinesin-microtubule complex. Loss of symmetry has functional consequences such as an asymmetric hand-over-hand mechanism in plus-end directed kinesins, asymmetric microtubule binding in the Kinesin-14 family, spatially biased stepping in dynein, and cooperative binding of additional motors to the microtubule. This review focuses on how the consequences of asymmetry affect regulation of motor heads within a dimer, dimers within an ensemble of motors, and suggests how these asymmetries may affect regulation of active transport within the cell. PMID:23066835

  1. Amplitude enhancement by a gold dimer

    NASA Astrophysics Data System (ADS)

    Hong, Xin; Wang, Jingxin; Jin, Zheng

    2016-10-01

    The unique optical properties such as brightness, non-bleaching, good bio-compatibility make gold particles ideal label candidates for molecular probes. Due to the strongly enhanced field, aggregation of gold nanoparticles finds themselves plenty of applications in bio-imaging. But limited by its small cross-section associated with nanometer sized particle, it is a big challenge to employ it in a single molecular detection. The field enhancement results from the effect of plasmonic coupling between two closely attached gold nanoparticle under the right excitation condition. With the aim to apply the gold dimer probe to find the molecules in our recently established optical detection method, we compared of the amplitude enhancement by the dimer relative to a single particle. The amplitude distribution under a highly focused illumination objective was calculated, whose results suggest that at the optimized excitation condition, the local field can be enhanced 190 fold. In consequence, experimental detection was carried out. Gold dimers were linked together by the hybridization of two single chain DNAs. Dimer and single particle probes were mixed together in one detection. Overwhelming contrast between these two kinds of probes were clearly exhibited in the experimental detection image. This method can provide a way to a high specific detection in early diagnosis.

  2. Stability and Formation of Isobutylene Dimers.

    ERIC Educational Resources Information Center

    Goldsmith, Robert H.

    1983-01-01

    Isobutylene is an important bulk chemical for the petroleum industry. Dimerization and hydrogenation reactions produce the standard fuel octane rating comparison. This classic chemistry is often misrepresented in modern texts, however, and this paper attempts to correlate the physical organic principles that apply. (Author)

  3. A new lignan dimer from Mallotus philippensis.

    PubMed

    Mai, Nguyen Thi; Cuong, Nguyen Xuan; Thao, Nguyen Phuong; Nam, Nguyen Hoai; Khoi, Nguyen Huu; Minh, Chau Van; Heyden, Yvan Vander; Thuan, Ngo Thi; Tuyen, Nguyen Van; Quetin-Leclercq, Joëlle; Kiem, Phan Van

    2010-03-01

    A new lignan dimer, bilariciresinol (1), was isolated from the leaves of Mallotus philippensis, along with platanoside (2), isovitexin (3), dihydromyricetin (4), bergenin (5), 4-O-galloylbergenin (6), and pachysandiol A (7). Their structures were elucidated by spectroscopic experiments including 1D and 2D NMR and FTICR-MS.

  4. What factors control dimerization of coniferyl alcohol?

    Treesearch

    Carl J. Houtman

    1999-01-01

    Data suggest that the dimerization of coniferyl alcohol is not under thermodynamic control. In this study, molecular dynamics calculations were used to estimate the effect of the solvent environment. In water, the coniferyl alcohol radicals were forced to associate by the formation of a solvent cage. In glycerol, the solvent cage effect appeared to be absent. These...

  5. Adsorption of dimeric surfactants in lamellar silicates

    NASA Astrophysics Data System (ADS)

    Balcerzak, Mateusz; Pietralik, Zuzanna; Domka, Ludwik; Skrzypczak, Andrzej; Kozak, Maciej

    2015-12-01

    The adsorption of different types of cationic surfactants in lamellar silicates changes their surface character from hydrophilic to hydrophobic. This study was undertaken to obtain lamellar silicates modified by a series of novel dimeric (gemini) surfactants of different length alkyl chains and to characterise these organophilised materials. Synthetic sodium montmorillonite SOMASIF® ME 100 (M) and enriched bentonite of natural origin (Nanoclay - hydrophilic bentonite®) were organophilised with dimeric (gemini) surfactants (1,1‧-(1,4-butanediyl)bis(alkoxymethyl)imidazolium dichlorides). As a result of surfactant molecule adsorption in interlamellar space, the d-spacing (d001) increased from 0.97 nm (for the anhydrous structure) to 2.04 nm. A Fourier transform infrared spectroscopy (FTIR) analysis of the modified systems reveals bands assigned to the stretching vibrations of the CH2 and CH3 groups and the scissoring vibrations of the NH group from the structure of the dimeric surfactants. Thermogravimetric (TG) and derivative thermogravimetric (DTG) studies imply a four-stage process of surfactant decomposition. Scanning electron microscopy (SEM) images provide information on the influence of dimeric surfactant intercalation into the silicate structures. Particles of the modified systems show a tendency toward the formation of irregularly shaped agglomerates.

  6. Thymine Dimer Formation probed by Time-Resolved Vibrational Spectroscopy

    NASA Astrophysics Data System (ADS)

    Schreier, Wolfgang J.; Schrader, Tobias E.; Roller, Florian O.; Gilch, Peter; Zinth, Wolfgang; Kohler, Bern

    Cyclobutane pyrimidine dimers are the major photoproducts formed when DNA is exposed to UV light. Femtosecond time-resolved vibrational spectroscopy reveals that thymine dimers are formed in thymidine oligonucleotides in an ultrafast photoreaction.

  7. Ligand regulation of a constitutively dimeric EGF receptor

    NASA Astrophysics Data System (ADS)

    Freed, Daniel M.; Alvarado, Diego; Lemmon, Mark A.

    2015-06-01

    Ligand-induced receptor dimerization has traditionally been viewed as the key event in transmembrane signalling by epidermal growth factor receptors (EGFRs). Here we show that the Caenorhabditis elegans EGFR orthologue LET-23 is constitutively dimeric, yet responds to its ligand LIN-3 without changing oligomerization state. SAXS and mutational analyses further reveal that the preformed dimer of the LET-23 extracellular region is mediated by its domain II dimerization arm and resembles other EGFR extracellular dimers seen in structural studies. Binding of LIN-3 induces only minor structural rearrangements in the LET-23 dimer to promote signalling. Our results therefore argue that EGFR can be regulated by allosteric changes within an existing receptor dimer--resembling signalling by insulin receptor family members, which share similar extracellular domain compositions but form covalent dimers.

  8. Protective Effect of Cyanidin-3-O-Glucoside against Ultraviolet B Radiation-Induced Cell Damage in Human HaCaT Keratinocytes.

    PubMed

    Hu, Yunfeng; Ma, Yuetang; Wu, Shi; Chen, Tianfeng; He, Yong; Sun, Jianxia; Jiao, Rui; Jiang, Xinwei; Huang, Yadong; Deng, Liehua; Bai, Weibin

    2016-01-01

    Ultraviolet radiation is the major environmental harmful factor that has emotional impact on human skin. The aim of the present study was to determine the mechanism of protection of cyanidin-3-O-glucoside against ultraviolet B (UVB)-induced damage to human HaCaT keratinocytes. Our results show that cyanidin-3-O-glucoside decreased the levels of intracellular reactive oxygen species generated by UVB treatment. Cyanidin-3-O-glucoside also decreased the UVB-augmented levels of the DNA damage indicators phospho-p53 and phospho-ATM/ATR. In addition, cyanidin-3-O-glucoside protected keratinocytes from UVB-induced injury by overturning the disruption of mitochondrial membrane potential and reversing apoptosis. The expression of anti-apoptotic protein B-cell lymphoma 2 (Bcl-2) was attenuated in UVB-exposed cells but restored in UVB/cyanidin-3-O-glucoside-treated cells. Furthermore, expression of the proapoptotic proteins Bcl-2-associated X (Bax) and the key apoptosis executer cleaved caspase-3 were increased in UVB-irradiated cells and decreased in UVB/cyanidin-3-O-glucoside-treated cells. For these reasons, the results demonstrate that cyanidin-3-O-glucoside protects human keratinocytes against UVB-induced oxidative stress and apoptosis. Our study provides a theoretical basis for the use of cyanidin-3-O-glucoside in the fight against light damage.

  9. Protective Effect of Cyanidin-3-O-Glucoside against Ultraviolet B Radiation-Induced Cell Damage in Human HaCaT Keratinocytes

    PubMed Central

    Hu, Yunfeng; Ma, Yuetang; Wu, Shi; Chen, Tianfeng; He, Yong; Sun, Jianxia; Jiao, Rui; Jiang, Xinwei; Huang, Yadong; Deng, Liehua; Bai, Weibin

    2016-01-01

    Ultraviolet radiation is the major environmental harmful factor that has emotional impact on human skin. The aim of the present study was to determine the mechanism of protection of cyanidin-3-O-glucoside against ultraviolet B (UVB)-induced damage to human HaCaT keratinocytes. Our results show that cyanidin-3-O-glucoside decreased the levels of intracellular reactive oxygen species generated by UVB treatment. Cyanidin-3-O-glucoside also decreased the UVB-augmented levels of the DNA damage indicators phospho-p53 and phospho-ATM/ATR. In addition, cyanidin-3-O-glucoside protected keratinocytes from UVB-induced injury by overturning the disruption of mitochondrial membrane potential and reversing apoptosis. The expression of anti-apoptotic protein B-cell lymphoma 2 (Bcl-2) was attenuated in UVB-exposed cells but restored in UVB/cyanidin-3-O-glucoside-treated cells. Furthermore, expression of the proapoptotic proteins Bcl-2-associated X (Bax) and the key apoptosis executer cleaved caspase-3 were increased in UVB-irradiated cells and decreased in UVB/cyanidin-3-O-glucoside-treated cells. For these reasons, the results demonstrate that cyanidin-3-O-glucoside protects human keratinocytes against UVB-induced oxidative stress and apoptosis. Our study provides a theoretical basis for the use of cyanidin-3-O-glucoside in the fight against light damage. PMID:27656146

  10. Two novel naphthalene glucosides and an anthraquinone isolated from Rumex dentatus and their antiproliferation activities in four cell lines.

    PubMed

    Zhang, Hui; Guo, Zengjun; Wu, Nan; Xu, Wenming; Han, Ling; Li, Nan; Han, Yanxia

    2012-01-17

    An ethyl acetate extract of the roots of Rumex dentatus L. was investigated. Three compounds were identified by their spectroscopic data as chrysophanol (1), 6-methyl-7-acetyl-1, 8-dihydroxy-3-methoxy naphthalene-1-O-β-D(L)-glucoside (2) and 6-methyl-7-acetyl-1, 8-dihydroxy naphthalene-1-O-β-D(L)-glucoside (3) were found in the plant for the first time. Compounds 2 and 3 are novel compounds. Their antiproliferation activities were tested by the MTT assay in four cell lines (breast cancer MCF-7, gastric cancer 7901, melanoma A375 and oophoroma SKOV-3).

  11. Localized light-induced protein dimerization in living cells using a photocaged dimerizer

    PubMed Central

    Ballister, Edward R.; Aonbangkhen, Chanat; Mayo, Alyssa M.; Lampson, Michael A.; Chenoweth, David M.

    2015-01-01

    Regulated protein localization is critical for many cellular processes. Several techniques have been developed for experimental control over protein localization, including chemically induced and light-induced dimerization, which both provide temporal control. Light-induced dimerization offers the distinct advantage of spatial precision within subcellular length scales. A number of elegant systems have been reported that utilize natural light-sensitive proteins to induce dimerization via direct protein–protein binding interactions, but the application of these systems at cellular locations beyond the plasma membrane has been limited. Here we present a new technique to rapidly and reversibly control protein localization in living cells with subcellular spatial resolution using a cell-permeable, photoactivatable chemical inducer of dimerization. We demonstrate light-induced recruitment of a cytosolic protein to individual centromeres, kinetochores, mitochondria and centrosomes in human cells, indicating that our system is widely applicable to many cellular locations. PMID:25400104

  12. Mechanism for covalent dimerization of pyridine: [4+2] dimerization, an MP2 investigation

    NASA Astrophysics Data System (ADS)

    Guo, Li-hui; Wang, Gui-lin; Yan, Zhi-e.; Zhang, Xiang

    2016-01-01

    The Diels⿿Alder (DA) covalent dimerization mechanisms of pyridine were studied at the MP2/6-311G(d,p) level. Involvement of N atom in DA reaction causes high barrier height, otherwise the barrier heights are low. The two most stable DI dimers formed by intermolecular DA reaction (b-γDI and b-γ⿲DI) and the two most stable DII dimers formed by further intramolecular DA reaction (c-γDII and c-γ⿲DII) were located with relative energy of 26.6 and 26.1 kcal/mol, and 32.1 and 31.6 kcal/mol, respectively, higher than two moles of pyridines. Theoretical results suggested that DA dimerization of pyridine is slightly easier than that of benzene.

  13. Extraction parameters and capillary electrophoresis analysis of limonin glucoside and phlorin in citrus byproducts.

    PubMed

    Braddock, R J; Bryan, C R

    2001-12-01

    Limonin glucoside (LG) and phlorin were extracted from citrus fruit tissues and assayed by capillary electrophoresis (CE). LG was determined in dried [1.20 +/- 0.10 mg of dry weight (dw)] and wet peel residues (1.16 +/- 0.04 mg of dw), orange juice finisher pulp (0.58 +/- 0.03 mg of dw), dried grapefruit seeds (2.70 +/- 0.15 mg of dw), and 50 degrees Brix molasses (2225 +/- 68 mg/L). Phlorin was purified from orange peel residue and grapefruit albedo, and concentrations were determined in some citrus products. Phlorin and LG were extracted from residues with water/pectinase or with water solutions of methanol and ethanol. Efficient LG extraction from grapefruit seeds (2.40 +/- 0.15 mg/g) was achieved with 50-65% methanol, solvent polarity P' approximately equal to 7-8. Extracts were purified and concentrated by adsorptive resins and HPLC to obtain 95% pure compounds of LG and phlorin. CE analysis did not require extract purification beyond filtration. LG and phlorin migrated as anions in electropherograms containing peaks representing other citrus flavonoids and limonoid glucosides.

  14. Assessment of cyanogenic glucoside (cyanide) residues in Mbege: an opaque traditional Tanzanian beer.

    PubMed

    Shayo, N B; Nnko, S A; Gidamis, A B; Dillon, V M

    1998-09-01

    Levels of cyanide in two varieties of malted millet, spent grain (Machicha) and opaque beer (Mbege) were determined. Protein content and amino acid composition of the malt, Mbege and Machicha were determined. Mbege was made in the laboratory using an improved method. The cyanide content of millet, malt, spent grain and Mbege were 40.6, 513.4, 18.9 and 8.1 ppm, respectively for the Moshi local millet variety. For Sumbawanga-2 millet variety the cyanide content was found to be 41.2, 489.2, 17.8 and 6.8 ppm for the millet, malt, spent grain and Mbege, respectively. The cyanide content increased linearly as the number of days of germination of the millet grain increased and the highest values of cyanide were attained on the third day of germination. Cyanogenic glucosides in the millet were enzymetically hydrolysed to respective cyanohydrins and volatile hydrogen cyanide due to low pH level of the Mbege which was 4. Malting of the millet increased the protein content by 5%. Lysine, the most limiting amino acid in millet, increased by 20%. It was concluded that the fermentation process of the millet malt into Mbege is efficient in reducing the levels of cyanogenic glucosides below levels considered toxic and therefore rendering the product safe.

  15. Malvidin 3-Glucoside-Fatty Acid Conjugates: From Hydrophilic toward Novel Lipophilic Derivatives.

    PubMed

    Cruz, Luís; Guimarães, Marta; Araújo, Paula; Évora, Ana; de Freitas, Victor; Mateus, Nuno

    2017-08-09

    This work describes the lipophilization reactions of malvidin 3-glucoside with different saturated fatty acid chain lengths using an enzymatic synthesis and the study of their physical-chemical and antioxidant properties. The lipophilic anthocyanins were obtained with satisfactory yields (22-40%) after column chromatography purifications, and they revealed the same appealing chromatic features of the parent anthocyanin. All of the compounds were characterized by mass spectrometry, confirming the regioselective acylation on the glucose moiety. The octanol-water partition coefficients and the hydrophobicity index of the different derivatives were determined, confirming a lipophilicity increase concomitant with the fatty acid chain length. The antioxidant profile was also evaluated by using two in vitro methods (β-carotene-lineolate method and oxygen consumption assay). Overall, a maximum of antioxidant activity was achieved when malvidin 3-glucoside was conjugated with caprylic acid (C8). Altogether, the results obtained provide a good perspective for the technological application of these functionalized anthocyanins in the cosmetics and food industries.

  16. Effects on Liver Lipid Metabolism of the Naturally Occurring Dietary Flavone Luteolin-7-glucoside

    PubMed Central

    Sá, Carla; Oliveira, Ana Rita; Machado, Cátia; Azevedo, Marisa; Pereira-Wilson, Cristina

    2015-01-01

    Disruptions in whole-body lipid metabolism can lead to the onset of several pathologies such as nonalcoholic fatty liver disease (NAFLD) and cardiovascular diseases (CVDs). The present study aimed at elucidating the molecular mechanisms behind the lipid-lowering effects of the flavone luteolin-7-glucoside (L7G) which we previously showed to improve plasma lipid profile in rats. L7G is abundant in plant foods of Mediterranean diet such as aromatic plants used as herbs. Results show that dietary supplementation with L7G for one week induced the expression of peroxisome proliferator-activated receptor-alpha (PPAR-α) and of its target gene carnitine palmitoyl transferase 1 (CPT-1) in rat liver. L7G showed a tendency to decrease the hepatic expression of sterol regulatory element-binding protein-1 (SREBP-1), without affecting fatty acid synthase (FAS) protein levels. Although SREBP-2 and LDLr mRNA levels did not change, the expression of HMG CoA reductase (HMGCR) was significantly repressed by L7G. L7G also inhibited this enzyme's in vitro activity in a dose dependent manner, but only at high and not physiologically relevant concentrations. These results add new evidence that the flavone luteolin-7-glucoside may help in preventing metabolic diseases and clarify the mechanisms underlying the beneficial health effects of diets rich in fruits and vegetables. PMID:26113868

  17. β-d-Glucosidase as "key enzyme" for sorghum cyanogenic glucoside (dhurrin) removal and beer bioflavouring.

    PubMed

    Tokpohozin, Sedjro Emile; Fischer, Susann; Sacher, Bertram; Becker, Thomas

    2016-11-01

    Sorghum malt used during African beer processing contains a high level of cyanogenic glucoside (dhurrin), up to 1375 ppm. In traditional sorghum malting and mashing, dhurrin is not sufficiently hydrolyzed due to uncontrolled germination and a high gelatinization temperature. The cyanide content of traditional African beers (11 ppm) is higher than the minimum dose (1 ppm) required to form carcinogenic ethyl carbamate during alcoholic fermentation. In the detoxification process, aryl-β-d-glucosidase (dhurrinase) is the "key component". For significant dhurrin hydrolysis during mashing, optimizing dhurrinase synthesis during malting is a good solution to reduce dhurrin completely to below the harmful dose in the sorghum wort. Lactic acid bacteria which exhibit aryl-β-d-glucosidase prior to alcoholic fermentation may help to reduce ethyl carbamate content in alcoholic beverages. Moreover, some specific β-d-glucosidases have a dual property, being able to cleave and synthesize glucosides bonds and thereby generating good precursors for beer bioflavouring.

  18. Cyanogenic Glucosides and Derivatives in Almond and Sweet Cherry Flower Buds from Dormancy to Flowering

    PubMed Central

    Del Cueto, Jorge; Ionescu, Irina A.; Pičmanová, Martina; Gericke, Oliver; Motawia, Mohammed S.; Olsen, Carl E.; Campoy, José A.; Dicenta, Federico; Møller, Birger L.; Sánchez-Pérez, Raquel

    2017-01-01

    Almond and sweet cherry are two economically important species of the Prunus genus. They both produce the cyanogenic glucosides prunasin and amygdalin. As part of a two-component defense system, prunasin and amygdalin release toxic hydrogen cyanide upon cell disruption. In this study, we investigated the potential role within prunasin and amygdalin and some of its derivatives in endodormancy release of these two Prunus species. The content of prunasin and of endogenous prunasin turnover products in the course of flower development was examined in five almond cultivars – differing from very early to extra-late in flowering time – and in one sweet early cherry cultivar. In all cultivars, prunasin began to accumulate in the flower buds shortly after dormancy release and the levels dropped again just before flowering time. In almond and sweet cherry, the turnover of prunasin coincided with increased levels of prunasin amide whereas prunasin anitrile pentoside and β-D-glucose-1-benzoate were abundant in almond and cherry flower buds at certain developmental stages. These findings indicate a role for the turnover of cyanogenic glucosides in controlling flower development in Prunus species. PMID:28579996

  19. Isoarnottinin 4'-glucoside, a glycosylated coumarin from Prangos uloptera, with biological activity.

    PubMed

    Razavi, Seyed Mehdi; Zarrini, Gholamreza; Rad, Farah Gholami

    2011-01-01

    Coumarins are a well-known group of natural products distributed in the plant kingdom especially in the family Apiaceae with various biological activities. Isoarnottinin 4'-glucoside is a simple glycosylated coumarin found previously in a few genera of Apiaceae, and its biological activities have not been previously described in details. In the present paper, the compound was isolated from Prangos uloptera (Apiaceae) leaves using HPLC techniques. Antimicrobial, phytotoxic and cytotoxic activities of the compound were evaluated by disk diffusion, lettuce assay and MTT method. Our results indicated that the compound has high antibacterial effect against Erwinia carotovora, a common plant pathogen with MIC value of 100 microg/mL. The compound also exhibited significant phytotoxic activity against lettuce and modest cytotoxic activity against HeLa cell line with IC50 of 0 .84 mg/mL. It could be concluded that isoamottinin 4'-glucoside may play phytoalexin or allelopathic role for plant and may be a candidate for an antibacterial agent or a bioherbicide.

  20. Development and Evaluation of Monoclonal Antibodies for the Glucoside of T-2 Toxin (T2-Glc)

    PubMed Central

    Maragos, Chris M.; Kurtzman, Cletus; Busman, Mark; Price, Neil; McCormick, Susan

    2013-01-01

    The interactions between fungi and plants can yield metabolites that are toxic in animal systems. Certain fungi are known to produce sesquiterpenoid trichothecenes, such as T-2 toxin, that are biotransformed by several mechanisms including glucosylation. The glucosylated forms have been found in grain and are of interest as potential reservoirs of T-2 toxin that are not detected by many analytical methods. Hence the glucosides of trichothecenes are often termed “masked” mycotoxins. The glucoside of T-2 toxin (T2-Glc) was linked to keyhole limpet hemocyanin and used to produce antibodies in mice. Ten monoclonal antibody (Mab)-producing hybridoma cell lines were developed. The Mabs were used in immunoassays to detect T2-Glc and T-2 toxin, with midpoints of inhibition curves (IC50s) in the low ng/mL range. Most of the Mabs demonstrated good cross-reactivity to T-2 toxin, with lower recognition of HT-2 toxin. One of the clones (2-13) was further characterized with in-depth cross-reactivity and solvent tolerance studies. Results suggest Mab 2-13 will be useful for the simultaneous detection of T-2 toxin and T2-Glc. PMID:23877196

  1. Glucosylation of Steviol and Steviol-Glucosides in Extracts from Stevia rebaudiana Bertoni

    PubMed Central

    Shibata, Hitoshi; Sonoke, Satoru; Ochiai, Hideo; Nishihashi, Hideji; Yamada, Masaharu

    1991-01-01

    To evaluate and characterize stevioside biosynthetic pathway in Stevia rebaudiana Bertoni cv Houten, two enzyme fractions that catalyze glucosylation of steviol (ent-13-hydroxy kaur-16-en-19-oic acid) and steviol-glucosides (steviol-13-O-glucopyranoside, steviolbioside and stevioside), utilizing UDP-glucose as the glucose donor, were prepared from the soluble extracts of S. rebaudiana leaves. Enzyme fraction I, passed through DEAE-Toyopearl equilibrated with 50 millimolar K-phosphate pH 7.5, catalyzed the glucosylation to steviol and 19-O-methylsteviol, but not to iso-steviol and 13-O-methylsteviol, indicating that 13-hydroxyl group of the steviol skeleton is glucosylated first from UDP-glucose to produce steviol-13-O-glucopyranoside. Enzyme fraction II, eluted from the DEAE-Toyopearl column with 0.15 molar KCI, catalyzed the glucose transfer from UDP-glucose to steviol-13-O-glucopyranoside, steviolbioside and stevioside, but not to rubusoside (13, 19-di-O-glucopyranoside) and rebaudioside A. The reaction products glucosylated from steviol-13-O-glucopyranoside, steviolbioside and stevioside were identified to be steviolbioside, stevioside and rebaudioside A, respectively. These results indicate that in the steviol-glucoside biosynthetic pathway, steviol-13-O-glucopyranoside produced from the steviol glucosylation is successively glucosylated to steviolbioside, then to stevioside producing rebaudioside A. PMID:16667943

  2. An experiment regarding crystallization of soluble proteins in the presence of beta-octyl glucoside.

    PubMed

    McPherson, A; Koszelak, S; Axelrod, H; Day, J; Williams, R; Robinson, L; McGrath, M; Cascio, D

    1986-02-05

    Twenty-one soluble proteins, five tRNAs, and three protein-nucleic acid complexes were studied in a systematic manner with regard to their crystallization behavior from polyethylene glycol and ammonium sulfate solutions in the presence of 0 to 1.5% beta-octyl glucoside. Our observations suggest that this neutral detergent does influence in a very positive way the growth characteristics of the macromolecules included in this experiment. In general, more reproducible and rapid growth was noted with an increased number of large individual crystals at the expense of microcrystals. In several cases, new crystal forms were discovered. Selected x-ray diffraction analyses imply that crystals grown in the presence of beta-octyl glucoside diffract as well or better than those grown in its absence. In addition, a screen of two proteins grown in the presence of 14 different common detergents suggested that a general detergent effect may be beneficial for the growth of crystals of biological macromolecules.

  3. New steroidal lactones and homomonoterpenic glucoside from fruits of Malva sylvestris L.

    PubMed

    Mustafa, Akhlaq; Ali, Mohammed

    2011-01-01

    Phytochemical investigation of the ethanolic extract of defatted fruits of Malva sylvestris Linn. (Malvaceae) led to the isolation of six new steroidal lactones and a homomonoterpenic glucoside along with beta-sitosterol-3-beta-D-glucopyranoside. The structures of new phytoconstituents have been elucidated as cholest-5-en-3a-ol-18(21)-olide (sylvestrosterol A), cholest-9(11)-en-3alpha-ol-18(21)-olide (sylvestrosterol B), cholest-4,6,22-trien-3alpha-ol-18(21)-olide (sylvestrosterol C), 2-methyl-6-methylene-n-decan-2-olyl- 3beta-D-glucopyranoside (malvanoyl glucoside), cholest-7-en-18(21)-olide-3alpha-olyl-3beta-D-glucopyranoside (sylvestrogenin A), cholest-9(11)-en-18(21)-olide-3alpha-olyl-3beta-D-glucopyranoside (sylvestrogenin B) and cholest-5-en-8(21)-olide-3alpha-olyl-3beta-D-glucopyranoside (sylvestrogenin C).The structures of all these phytoconstituents have been established on the basis of spectral data analysis and chemical reactions.

  4. Dimerization of visual pigments in vivo

    PubMed Central

    Zhang, Tao; Cao, Li-Hui; Kumar, Sandeep; Enemchukwu, Nduka O.; Zhang, Ning; Lambert, Alyssia; Zhao, Xuchen; Jones, Alex; Wang, Shixian; Dennis, Emily M.; Fnu, Amrita; Ham, Sam; Rainier, Jon; Yau, King-Wai; Fu, Yingbin

    2016-01-01

    It is a deeply engrained notion that the visual pigment rhodopsin signals light as a monomer, even though many G protein-coupled receptors are now known to exist and function as dimers. Nonetheless, recent studies (albeit all in vitro) have suggested that rhodopsin and its chromophore-free apoprotein, R-opsin, may indeed exist as a homodimer in rod disk membranes. Given the overwhelmingly strong historical context, the crucial remaining question, therefore, is whether pigment dimerization truly exists naturally and what function this dimerization may serve. We addressed this question in vivo with a unique mouse line (S-opsin+Lrat−/−) expressing, transgenically, short-wavelength–sensitive cone opsin (S-opsin) in rods and also lacking chromophore to exploit the fact that cone opsins, but not R-opsin, require chromophore for proper folding and trafficking to the photoreceptor’s outer segment. In R-opsin’s absence, S-opsin in these transgenic rods without chromophore was mislocalized; in R-opsin’s presence, however, S-opsin trafficked normally to the rod outer segment and produced functional S-pigment upon subsequent chromophore restoration. Introducing a competing R-opsin transmembrane helix H1 or helix H8 peptide, but not helix H4 or helix H5 peptide, into these transgenic rods caused mislocalization of R-opsin and S-opsin to the perinuclear endoplasmic reticulum. Importantly, a similar peptide-competition effect was observed even in WT rods. Our work provides convincing evidence for visual pigment dimerization in vivo under physiological conditions and for its role in pigment maturation and targeting. Our work raises new questions regarding a potential mechanistic role of dimerization in rhodopsin signaling. PMID:27462111

  5. Red clover Trifolium pratense L. phytoestrogens: UV-B radiation increases isoflavone yield, and postharvest drying methods change the glucoside conjugate profiles.

    PubMed

    Swinny, Ewald E; Ryan, Ken G

    2005-10-19

    Isoflavone extracts of red clover Trifolium pratense L. (cv. Pawera) with dissimilar glucoside conjugate profiles were obtained by employing different postharvest drying methods. The most prominent isoflavones found were formononetin and biochanin A and their corresponding glucosides and malonyl glucoside esters. Postharvest freeze drying inhibited the conversion of the glycosides to the aglycones, while vacuum drying allowed for maximum conversion of the glycosides to their corresponding aglycones. Air drying produced a low level of the aglycones formononetin and biochanin A, and oven drying promoted decarboxylation of the malonyl glucosides to the acetyl glucosides. Exposure to enhanced UV-B radiation resulted in an increase in total formononetin and biochanin A isoflavone levels, indicating that harvest during a period of high ambient UV-B radiation may be appropriate for maximum yield. The levels of caffeic acid and flavonols also increased by about 40 and 250%, respectively, on exposure to enhanced UV-B radiation.

  6. Ultraviolet Spectrum And Chemical Reactivity Of CIO Dimer

    NASA Technical Reports Server (NTRS)

    Demore, William B.; Tschuikow-Roux, E.

    1992-01-01

    Report describes experimental study of ultraviolet spectrum and chemical reactivity of dimer of chlorine monoxide (CIO). Objectives are to measure absorption cross sections of dimer at near-ultraviolet wavelengths; determine whether asymmetrical isomer (CIOCIO) exists at temperatures relevant to Antarctic stratosphere; and test for certain chemical reactions of dimer. Important in photochemistry of Antarctic stratosphere.

  7. Dimer monomer transition and dimer re-formation play important role for ATM cellular function during DNA repair.

    PubMed

    Du, Fengxia; Zhang, Minjie; Li, Xiaohua; Yang, Caiyun; Meng, Hao; Wang, Dong; Chang, Shuang; Xu, Ye; Price, Brendan; Sun, Yingli

    2014-10-03

    The ATM protein kinase, is a serine/threonine protein kinase that is recruited and activated by DNA double-strand breaks, mediates responses to ionizing radiation in mammalian cells. Here we show that ATM is held inactive in unirradiated cells as a dimer and phosphorylates the opposite strand of the dimer in response to DNA damage. Cellular irradiation induces rapid intermolecular autophosphorylation of serine 1981 that causes dimer dissociation and initiates cellular ATM kinase activity. ATM cannot phosphorylate the substrates when it could not undergo dimer monomer transition. After DNA repair, the active monomer will undergo dephosphorylation to form dimer again and dephosphorylation is critical for dimer re-formation. Our work reveals novel function of ATM dimer monomer transition and explains why ATM dimer monomer transition plays such important role for ATM cellular activity during DNA repair.

  8. Synthesis of Mono- and Di-Glucosides of Zearalenone and α-/β-Zearalenol by Recombinant Barley Glucosyltransferase HvUGT14077

    PubMed Central

    Michlmayr, Herbert; Varga, Elisabeth; Lupi, Francesca; Malachová, Alexandra; Hametner, Christian; Berthiller, Franz; Adam, Gerhard

    2017-01-01

    Zearalenone (ZEN) is an estrogenic mycotoxin occurring in Fusarium-infected cereals. Glucosylation is an important plant defense mechanism and generally reduces the acute toxicity of mycotoxins to humans and animals. Toxicological information about ZEN-glucosides is limited due to the unavailability of larger amounts required for animal studies. HvUGT14077, a recently-validated ZEN-conjugating barley UDP-glucosyltransferase was expressed in Escherichia coli, affinity purified, and characterized. HvUGT14077 possesses high affinity (Km = 3 µM) and catalytic efficiency (kcat/Km = 190 s−1·mM−1) with ZEN. It also efficiently glucosylates the phase-I ZEN-metabolites α-zearalenol and β-zearalenol, with kcat/Km of 40 and 74 s−1·mM−1, respectively. HvUGT14077 catalyzes O-glucosylation at C-14 and C-16 with preference of 14-glucoside synthesis. Furthermore, relatively slow consecutive formation of 14,16-di-glucosides was observed; their structures were tentatively identified by mass spectrometry and for ZEN-14,16-di-glucoside confirmed by nuclear magnetic resonance spectroscopy. Recombinant HvUGT14077 allowed efficient preparative synthesis of ZEN-glucosides, yielding about 90% ZEN-14-glucoside and 10% ZEN-16-glucoside. The yield of ZEN-16-glucoside could be increased to 85% by co-incubation with a β-glucosidase highly selective for ZEN-14-glucoside. Depletion of the co-substrate UDP-glucose was counteracted by a sucrose synthase based regeneration system. This strategy could also be of interest to increase the yield of minor glucosides synthesized by other glucosyltransferases. PMID:28208765

  9. Synthesis of Mono- and Di-Glucosides of Zearalenone and α-/β-Zearalenol by Recombinant Barley Glucosyltransferase HvUGT14077.

    PubMed

    Michlmayr, Herbert; Varga, Elisabeth; Lupi, Francesca; Malachová, Alexandra; Hametner, Christian; Berthiller, Franz; Adam, Gerhard

    2017-02-09

    Zearalenone (ZEN) is an estrogenic mycotoxin occurring in Fusarium-infected cereals. Glucosylation is an important plant defense mechanism and generally reduces the acute toxicity of mycotoxins to humans and animals. Toxicological information about ZEN-glucosides is limited due to the unavailability of larger amounts required for animal studies. HvUGT14077, a recently-validated ZEN-conjugating barley UDP-glucosyltransferase was expressed in Escherichia coli, affinity purified, and characterized. HvUGT14077 possesses high affinity (Km = 3 µM) and catalytic efficiency (kcat/Km = 190 s(-1)·mM(-1)) with ZEN. It also efficiently glucosylates the phase-I ZEN-metabolites α-zearalenol and β-zearalenol, with kcat/Km of 40 and 74 s(-1)·mM(-1), respectively. HvUGT14077 catalyzes O-glucosylation at C-14 and C-16 with preference of 14-glucoside synthesis. Furthermore, relatively slow consecutive formation of 14,16-di-glucosides was observed; their structures were tentatively identified by mass spectrometry and for ZEN-14,16-di-glucoside confirmed by nuclear magnetic resonance spectroscopy. Recombinant HvUGT14077 allowed efficient preparative synthesis of ZEN-glucosides, yielding about 90% ZEN-14-glucoside and 10% ZEN-16-glucoside. The yield of ZEN-16-glucoside could be increased to 85% by co-incubation with a β-glucosidase highly selective for ZEN-14-glucoside. Depletion of the co-substrate UDP-glucose was counteracted by a sucrose synthase based regeneration system. This strategy could also be of interest to increase the yield of minor glucosides synthesized by other glucosyltransferases.

  10. Freezing and melting behavior of an octyl β-D-glucoside-water binary system--inhibitory effect of octyl β-D-glucoside on ice crystal formation.

    PubMed

    Ogawa, Shigesaburo; Asakura, Kouichi; Osanai, Shuichi

    2012-12-21

    Phase transition behavior of lyotropic liquid crystals of an octyl β-D-glucoside (OG)-water binary system during ice freezing and melting was studied by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Not the thermotropic, but the lyotropic phase transition due to the change of OG concentration during ice freezing and melting was observed. The concentration-temperature phase diagram of the binary system was constructed. Melting temperature of ice, T(m), lyotropic phase transition temperature, T(tr), and glass transition temperatures of unfrozen phases in the absence and presence of ice, T(g) and T(g)', were shown in the phase diagram. The phase diagram indicated that the OG aqueous system was concentrated to ca. 90-92 wt% by ice freezing and exhibited glass transition at T(g)'. An observation of the concentration-gradient specimen by the cryo-POM showed the evidence of the inhibitory effects of OG on nucleation and growth of ice crystals in the extremely high OG concentration system in which the lamellar liquid crystalline phase was formed. This study provided the importance of the influence of concentration change by ice freezing on the behaviour of the sugar-based surfactant-water system under low temperature conditions.

  11. Scattering properties of weakly bound dimers of fermionic atoms

    SciTech Connect

    Petrov, D.S.; Salomon, C.; Shlyapnikov, G.V.

    2005-01-01

    We consider weakly bound diatomic molecules (dimers) formed in a two-component atomic Fermi gas with a large positive scattering length for the interspecies interaction. We develop a theoretical approach for calculating atom-dimer and dimer-dimer elastic scattering and for analyzing the inelastic collisional relaxation of the molecules into deep bound states. This approach is based on the single-channel zero-range approximation, and we find that it is applicable in the vicinity of a wide two-body Feshbach resonance. Our results draw prospects for various interesting manipulations of weakly bound dimers of fermionic atoms.

  12. Pyrimidine dimer formation and repair in human skin

    SciTech Connect

    Sutherland, B.M.; Harber, L.C.; Kochevar, I.E.

    1980-09-01

    Cyclobutyl pyrimidine dimers have been detected in the DNA of human skin following in vivo irradiation with suberythermal doses of ultraviolet (UV) radiation from FS-20 sun lamp fluorescent tubes. Dimers were assayed by treatment of extracted DNA with Micrococus luteus UV-specific endonuclease, alkaline agarose electrophoresis, and ethidum bromide staining. This technique, in contrast to conventional dimer assays, can be used with nonradioactive DNA and is optimal at low UV light doses. These data suggest that some dimer disappearance by excision repair occurs within 20 min of UV irradiation and that photoreactivation of dimers can make a contribution to the total repair process.

  13. On the Pyrazine and Pyrazine-Pyrimidine Dimers.

    DTIC Science & Technology

    1986-06-01

    Lennard - Jones -hydrogen-bonding (LJ-HB) potential energy calculations. The pyrazine isotopic hetero- and homo-dimers possess nearly identical spectra with the exception that the perpendicular dimer features are displaced to the red by approx. 11 cm. Exchange or exciton interactions in this system are vanishingly small (less than 1/cm). The geometrics suggested by the isotopically substituted pyrazine dimer spectra are the same as those found for the pyrazine-h sub 4 homo-dimer: a parallel planar hydrogen bonded and a perpendicular dimer. The pyrazine-h sub 4 and pyrazine-h

  14. Dimerization of recombinant horseradish peroxidase in a reversed micellar system.

    PubMed

    Klyachko, N L; Dulkis YuK; Gazaryan, I G; Ouporov, I V; Levashov, A V

    1997-10-01

    Recombinant horseradish peroxidase reactivated from E. coli inclusion bodies was studied in a reversed micellar system of AOT in octane. The ability of the recombinant enzyme, in contrast to native horseradish peroxidase, to form a dimeric structure was found. The existence of the dimer was proved by results of sedimentation analysis. Dimer/monomer ratio in the enzyme-containing micelles and dimer catalytic activity were found to depend on the substrate used (pyrogallol, guaiacol, o-dianisidine, o-phenylenediamine). Computer modelling was used to describe possible structures of the dimeric recombinant horseradish peroxidase.

  15. Calcium-dependent Dimerization of Human Soluble Calcium Activated Nucleotidase: Characterization of the Dimer Interface

    SciTech Connect

    Yang,M.; Horii, K.; Herr, A.; Kirley, T.

    2006-01-01

    Mammals express a protein homologous to soluble nucleotidases used by blood-sucking insects to inhibit host blood clotting. These vertebrate nucleotidases may play a role in protein glycosylation. The activity of this enzyme family is strictly dependent on calcium, which induces a conformational change in the secreted, soluble human nucleotidase. The crystal structure of this human enzyme was recently solved; however, the mechanism of calcium activation and the basis for the calcium-induced changes remain unclear. In this study, using analytical ultracentrifugation and chemical cross-linking, we show that calcium or strontium induce noncovalent dimerization of the soluble human enzyme. The location and nature of the dimer interface was elucidated using a combination of site-directed mutagenesis and chemical cross-linking, coupled with crystallographic analyses. Replacement of Ile{sup 170}, Ser{sup 172}, and Ser{sup 226} with cysteine residues resulted in calcium-dependent, sulfhydryl-specific intermolecular cross-linking, which was not observed after cysteine introduction at other surface locations. Analysis of a super-active mutant, E130Y, revealed that this mutant dimerized more readily than the wild-type enzyme. The crystal structure of the E130Y mutant revealed that the mutated residue is found in the dimer interface. In addition, expression of the full-length nucleotidase revealed that this membrane-bound form can also dimerize and that these dimers are stabilized by spontaneous oxidative cross-linking of Cys{sup 30}, located between the single transmembrane helix and the start of the soluble sequence. Thus, calcium-mediated dimerization may also represent a mechanism for regulation of the activity of this nucleotidase in the physiological setting of the endoplasmic reticulum or Golgi.

  16. Flavonoid C-glucosides Derived from Flax Straw Extracts Reduce Human Breast Cancer Cell Growth In vitro and Induce Apoptosis

    PubMed Central

    Czemplik, Magdalena; Mierziak, Justyna; Szopa, Jan; Kulma, Anna

    2016-01-01

    Flax straw of flax varieties that are grown for oil production is a by product which represents a considerable biomass source. Therefore, its potential application for human use is of high interest. Our research has revealed that flax straw is rich in flavonoid C-glucosides, including vitexin, orientin, and isoorientin. The objective of this study was to evaluate the cytotoxicity and possible proapoptotic effect of flax straw derived C-glucosides of flavonoids in the human breast adenocarcinoma cell line (MCF-7). The effects of flax straw derived flavonoid C-glucosides on cell proliferation of MCF-7 cells were evaluated by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) and sulforhodamine B assays. The expression of apoptosis-related genes was assessed by real-time PCR. Our data revealed that flax C-glucosides as well as pure compounds are cytotoxic toward MCF-7 cells and inhibit their proliferation. Moreover, the induction of apoptosis was correlated with the changes in the mRNA level of pro-apoptotic genes. Increased expression of bax and caspase-7, -8, and -9 and decreased mRNA expression of bcl-2 was observed, whereas the mRNA levels of p53 and mdm2 were not altered. These results clearly demonstrated that flax straw metabolites effectively induced growth inhibition and apoptosis in human breast adenocarcinoma cells. PMID:27630565

  17. Flavonoid C-glucosides Derived from Flax Straw Extracts Reduce Human Breast Cancer Cell Growth In vitro and Induce Apoptosis.

    PubMed

    Czemplik, Magdalena; Mierziak, Justyna; Szopa, Jan; Kulma, Anna

    2016-01-01

    Flax straw of flax varieties that are grown for oil production is a by product which represents a considerable biomass source. Therefore, its potential application for human use is of high interest. Our research has revealed that flax straw is rich in flavonoid C-glucosides, including vitexin, orientin, and isoorientin. The objective of this study was to evaluate the cytotoxicity and possible proapoptotic effect of flax straw derived C-glucosides of flavonoids in the human breast adenocarcinoma cell line (MCF-7). The effects of flax straw derived flavonoid C-glucosides on cell proliferation of MCF-7 cells were evaluated by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) and sulforhodamine B assays. The expression of apoptosis-related genes was assessed by real-time PCR. Our data revealed that flax C-glucosides as well as pure compounds are cytotoxic toward MCF-7 cells and inhibit their proliferation. Moreover, the induction of apoptosis was correlated with the changes in the mRNA level of pro-apoptotic genes. Increased expression of bax and caspase-7, -8, and -9 and decreased mRNA expression of bcl-2 was observed, whereas the mRNA levels of p53 and mdm2 were not altered. These results clearly demonstrated that flax straw metabolites effectively induced growth inhibition and apoptosis in human breast adenocarcinoma cells.

  18. In vitro anti-HIV-1 activities of kaempferol and kaempferol-7-O-glucoside isolated from Securigera securidaca.

    PubMed

    Behbahani, M; Sayedipour, S; Pourazar, A; Shanehsazzadeh, M

    2014-01-01

    Previously, we reported that the kaempferol and kaempferol-7-O-glucoside isolated from Securigera securidaca showed potent anti-HSV activity. In the present study the anti-HIV-1 activities of kaempferol and kaempferol-7-O-glucoside are investigated at different concentrations (100, 50, 25 and 10 μg/ml) using HIV-1 p24 Antigen kit. Real-time Polymerase chain reaction (RT-PCR) assay was also used for quantification of full range of virus load observed in treated and untreated cells. According to the results of RT- PCR, tested compounds at a concentration of 100 μg/ml exerted potent inhibitory effect. Time of drug addition experiments demonstrated that these compounds exerted their inhibitory effects on the early stage of HIV infection. The results also showed potent anti-HIV-1 reverse transcriptase activity. Antiviral activity of kaempferol-7-O-glucoside was more pronounced than that of kaempferol. These findings demonstrate that kaempferol-7-O-glucoside could be considered as a new potential drug candidate for the treatment of HIV infection which requires further assessments.

  19. A UDP-glucosyltransferase functions in both acylphloroglucinol glucoside and anthocyanin biosynthesis in strawberry (Fragaria × ananassa).

    PubMed

    Song, Chuankui; Zhao, Shuai; Hong, Xiaotong; Liu, Jingyi; Schulenburg, Katja; Schwab, Wilfried

    2016-03-01

    Physiologically active acylphloroglucinol (APG) glucosides were recently found in strawberry (Fragaria sp.) fruit. Although the formation of the APG aglycones has been clarified, little is known about APG glycosylation in plants. In this study we functionally characterized ripening-related glucosyltransferase genes in Fragaria by comprehensive biochemical analyses of the encoded proteins and by a RNA interference (RNAi) approach in vivo. The allelic proteins UGT71K3a/b catalyzed the glucosylation of diverse hydroxycoumarins, naphthols and flavonoids as well as phloroglucinols, enzymatically synthesized APG aglycones and pelargonidin. Total enzymatic synthesis of APG glucosides was achieved by co-incubation of recombinant dual functional chalcone/valerophenone synthase and UGT71K3 proteins with essential coenzyme A esters and UDP-glucose. An APG glucoside was identified in strawberry fruit which has not yet been reported in other plants. Suppression of UGT71K3 activity in transient RNAi-silenced fruits led to a loss of pigmentation and a substantial decrease of the levels of various APG glucosides and an anthocyanin. Metabolite analyses of transgenic fruits confirmed UGT71K3 as a UDP-glucose:APG glucosyltransferase in planta. These results provide the foundation for the breeding of fruits with improved health benefits and for the biotechnological production of bioactive natural products.

  20. The biosynthetic gene cluster for the cyanogenic glucoside dhurrin in Sorghum bicolor contains its co-expressed vacuolar MATE transporter

    PubMed Central

    Darbani, Behrooz; Motawia, Mohammed Saddik; Olsen, Carl Erik; Nour-Eldin, Hussam H.; Møller, Birger Lindberg; Rook, Fred

    2016-01-01

    Genomic gene clusters for the biosynthesis of chemical defence compounds are increasingly identified in plant genomes. We previously reported the independent evolution of biosynthetic gene clusters for cyanogenic glucoside biosynthesis in three plant lineages. Here we report that the gene cluster for the cyanogenic glucoside dhurrin in Sorghum bicolor additionally contains a gene, SbMATE2, encoding a transporter of the multidrug and toxic compound extrusion (MATE) family, which is co-expressed with the biosynthetic genes. The predicted localisation of SbMATE2 to the vacuolar membrane was demonstrated experimentally by transient expression of a SbMATE2-YFP fusion protein and confocal microscopy. Transport studies in Xenopus laevis oocytes demonstrate that SbMATE2 is able to transport dhurrin. In addition, SbMATE2 was able to transport non-endogenous cyanogenic glucosides, but not the anthocyanin cyanidin 3-O-glucoside or the glucosinolate indol-3-yl-methyl glucosinolate. The genomic co-localisation of a transporter gene with the biosynthetic genes producing the transported compound is discussed in relation to the role self-toxicity of chemical defence compounds may play in the formation of gene clusters. PMID:27841372

  1. Sulfated Glucosides of an Aliphatic Alcohol and Monoterpenes, and Megastigmanes from the Leaves of Meliosma pinnata spp. arnottiana.

    PubMed

    Uemura, Yuka; Kawakami, Susumu; Sugimoto, Sachiko; Matsunami, Katsuyoshi; Otsuka, Hideaki; Shinzato, Takakazu

    2016-01-01

    Chemical study of the leaves of Meliosma pinnata spp. arnottiana afforded five sulfated glucosides of oct-1-en-3-ol (1) and cyclic linalool derivatives (2-5), and two megastigmanes (6, 7). Their structures were elucidated by extensive investigation of one- and two-dimensional NMR spectroscopic data, and the absolute structures of the megastigmanes were determined by the modified Mosher's method.

  2. Boronate affinity-based surface molecularly imprinted polymers using glucose as fragment template for excellent recognition of glucosides.

    PubMed

    Peng, Mijun; Xiang, Haiyan; Hu, Xin; Shi, Shuyun; Chen, Xiaoqing

    2016-11-25

    Rapid and efficient extraction of bioactive glycosides from complex natural origins poses a difficult challenge, and then is often inherent bottleneck for their highly utilization. Herein, we propose a strategy to fabricate boronate affinity based surface molecularly imprinted polymers (MIPs) for excellent recognition of glucosides. d-glucose was used as fragment template. Boronic acid, dynamic covalent binding with d-glucose under different pH conditions, was selected as functional monomer to improve specificity. Fe3O4 solid core for surface imprinting using tetraethyl orthosilicate (TEOS) as crosslinker could control imprinted shell thickness for favorable adsorption capacity and satisfactory mass transfer rate, improve hydrophilicity, separate easily by a magnet. Model adsorption studies showed that the resulting MIPs show specific recognition of glucosides. The equilibrium data fitted well to Langmuir equation and the adsorption process could be described by pseudo-second order model. Furthermore, the MIPs were successfully applied for selective extraction of three flavonoid glucosides (daidzin, glycitin, and genistin) from soybean. Results indicated that selective extraction of glucosides from complex aqueous media based on the prepared MIPs is simple, rapid, efficient and specific. Moreover, this method opens up a universal route for imprinting saccharide with cis-diol group for glycosides recognition. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Anti-diabetic potential of ursolic acid stearoyl glucoside: a new triterpenic gycosidic ester from Lantana camara.

    PubMed

    Kazmi, Imran; Rahman, Mahfoozur; Afzal, Muhammad; Gupta, Gaurav; Saleem, Shakir; Afzal, Obaid; Shaharyar, Md Adil; Nautiyal, Ujjwal; Ahmed, Sayeed; Anwar, Firoz

    2012-01-01

    A new stearoyl glucoside of ursolic acid, urs-12-en-3β-ol-28-oic acid 3β-D-glucopyranosyl-4'-octadecanoate and other compounds were isolated from the leaves of Lantana camara L. The structure of this new glycoside was elucidated and established by standard spectroscopic methods. In streptozotocin-induced diabetic rats it showed significant reduction in blood glucose level.

  4. Note: cyclohexenoesculetin-beta-D-glucoside: a new substrate for the detection of bacterial beta-D-glucosidase.

    PubMed

    James, A L; Perry, J D; Ford, M; Armstrong, L; Gould, F K

    1997-04-01

    A new substrate for the detection of bacterial beta-D-glucosidase was evaluated as an alternative to aesculin. This substrate, 3,4-cyclohexenoesculetin-7-beta-D-glucoside, was compared with aesculin for the detection of beta-D-glucosidase in 150 enterococci, 40 streptococci, 12 Listeria sp. and 250 strains of Enterobacteriaceae. In the Gram-positive strains tested, aesculin hydrolysis correlated with hydrolysis of 3,4-cyclohexenoesculetin-7-beta-D-glucoside. In the Gram-negative strains the new substrate was hydrolysed by all aesculin-positive strains and also by four strains (10%) of Escherichia coli which gave a negative aesculin reaction. 3,4-Cyclohexenoesculetin-7-beta-D-glucoside was shown to be a reliable alternative to aesculin and was shown to have significant advantages over aesculin when incorporated into solid media. This was due to the non-diffusible end product produced by hydrolysis of 3,4-cyclohexenoesculetin-7-beta-D-glucoside in the presence of iron.

  5. A Comparative Analysis of the Photo-Protective Effects of Soy Isoflavones in Their Aglycone and Glucoside Forms

    PubMed Central

    Iovine, Barbara; Iannella, Maria Luigia; Gasparri, Franco; Giannini, Valentina; Monfrecola, Giuseppe; Bevilacqua, Maria Assunta

    2012-01-01

    Isoflavones exist in nature predominantly as glucosides such as daidzin or genistin and are rarely found in their corresponding aglycone forms daidzein and genistein. The metabolism and absorption of isoflavones ingested with food is well documented, but little is known about their use as topical photo-protective agents. The aim of this study was to investigate in a comparative analysis the photo-protective effects of isoflavones in both their aglycone and glucoside forms. In human skin fibroblasts irradiated with 60 mJ/cm2 ultraviolet B (UVB), we measured the expression levels of COX-2 and Gadd45, which are involved in inflammation and DNA repair, respectively. We also determined the cellular response to UVB-induced DNA damage using the comet assay. Our findings suggest that both the isoflavone glucosides at a specific concentration and combination with an aglycone mixture exerted an anti-inflammatory and photo-protective effect that prevented 41% and 71% of UVB-induced DNA damage, respectively. The advantages of using either isoflavone glucosides or an aglycone mixture in applications in the field of dermatology will depend on their properties and their different potential uses. PMID:23211668

  6. A comparative analysis of the photo-protective effects of soy isoflavones in their aglycone and glucoside forms.

    PubMed

    Iovine, Barbara; Iannella, Maria Luigia; Gasparri, Franco; Giannini, Valentina; Monfrecola, Giuseppe; Bevilacqua, Maria Assunta

    2012-12-04

    Isoflavones exist in nature predominantly as glucosides such as daidzin or genistin and are rarely found in their corresponding aglycone forms daidzein and genistein. The metabolism and absorption of isoflavones ingested with food is well documented, but little is known about their use as topical photo-protective agents. The aim of this study was to investigate in a comparative analysis the photo-protective effects of isoflavones in both their aglycone and glucoside forms. In human skin fibroblasts irradiated with 60 mJ/cm2 ultraviolet B (UVB), we measured the expression levels of COX-2 and Gadd45, which are involved in inflammation and DNA repair, respectively. We also determined the cellular response to UVB-induced DNA damage using the comet assay. Our findings suggest that both the isoflavone glucosides at a specific concentration and combination with an aglycone mixture exerted an anti-inflammatory and photo-protective effect that prevented 41% and 71% of UVB-induced DNA damage, respectively. The advantages of using either isoflavone glucosides or an aglycone mixture in applications in the field of dermatology will depend on their properties and their different potential uses.

  7. Minimization of a Protein–DNA Dimerizer

    PubMed Central

    Stafford, Ryan L.; Arndt, Hans-Dieter; Brezinski, Mary L.; Ansari, Aseem Z.; Dervan, Peter B.

    2011-01-01

    A protein–DNA dimerizer constructed from a DNA-binding polyamide and the peptide FYPWMKG facilitates the binding of a natural transcription factor Exd to an adjacent DNA site. The Exd binding domain can be reduced to a dipeptide WM attached to the polyamide through an ε-aminohexanoic acid linker with retention of protein–DNA dimerizer activity. Screening a library of analogues indicated that the tryptophan indole moiety is more important than methionine’s side chain or the N-terminal acetamide. Remarkably, switching the stereochemistry of the tryptophan residue (l to d) stabilizes the dimerizer•Exd•DNA ternary complex at 37 °C. These observations provide design principles for artificial transcription factors that may function in concert with the cellular regulatory circuitry. PMID:17290996

  8. Fibrillar dimer formation of islet amyloid polypeptides

    SciTech Connect

    Chiu, Chi -cheng; de Pablo, Juan J.

    2015-05-08

    Amyloid deposits of human islet amyloid polypeptide (hIAPP), a 37-residue hormone co-produced with insulin, have been implicated in the development of type 2 diabetes. Residues 20 – 29 of hIAPP have been proposed to constitute the amyloidogenic core for the aggregation process, yet the segment is mostly unstructured in the mature fibril, according to solid-state NMR data. Here we use molecular simulations combined with bias-exchange metadynamics to characterize the conformational free energies of hIAPP fibrillar dimer and its derivative, pramlintide. We show that residues 20 – 29 are involved in an intermediate that exhibits transient β-sheets, consistent with recent experimental and simulation results. By comparing the aggregation of hIAPP and pramlintide, we illustrate the effects of proline residues on inhibition of the dimerization of IAPP. The mechanistic insights presented here could be useful for development of therapeutic inhibitors of hIAPP amyloid formation.

  9. Electronic Transitions of Palladium and Vanadium Dimer

    NASA Astrophysics Data System (ADS)

    Qian, Yue; Ng, Y. W.; Cheung, A. S.-C.

    2013-06-01

    The laser induced fluorescence (LIF) spectrum of palladium dimer (Pd_{2}) in the visible region between 480 and 700 nm has been studied. Five vibrational bands were recorded and analyzed; they are assigned to a ^{3} Π _{g} - X^{3} Σ _{u} ^{+} system. The vibrational frequency of the ground X^{3} Σ _{u} ^{+} state has been determined to be 211.4 cm^{-1}. This is the first experimental observation of the LIF spectrum of Pd_{2}. In addition, the LIF spectrum of vanadium dimer (V_{2}) has also been studied; several new transition band systems were observed in the wavelength between 480 and 530 nm. The analysis of the spectra recorded for these two molecules will be presented.

  10. Fibrillar dimer formation of islet amyloid polypeptides

    NASA Astrophysics Data System (ADS)

    Chiu, Chi-cheng; de Pablo, Juan J.

    2015-09-01

    Amyloid deposits of human islet amyloid polypeptide (hIAPP), a 37-residue hormone co-produced with insulin, have been implicated in the development of type 2 diabetes. Residues 20 - 29 of hIAPP have been proposed to constitute the amyloidogenic core for the aggregation process, yet the segment is mostly unstructured in the mature fibril, according to solid-state NMR data. Here we use molecular simulations combined with bias-exchange metadynamics to characterize the conformational free energies of hIAPP fibrillar dimer and its derivative, pramlintide. We show that residues 20 - 29 are involved in an intermediate that exhibits transient β-sheets, consistent with recent experimental and simulation results. By comparing the aggregation of hIAPP and pramlintide, we illustrate the effects of proline residues on inhibition of the dimerization of IAPP. The mechanistic insights presented here could be useful for development of therapeutic inhibitors of hIAPP amyloid formation.

  11. Excitonic interaction in the fluorene dimer

    NASA Astrophysics Data System (ADS)

    Wessel, John; Beck, Steven; Highstrete, Clark

    1994-12-01

    The fluorene van der Waals dimer exhibits a complex origin spectrum. This region has been studied by resonance two-photon ionization and by fluorescence excitation spectroscopies. The spectra can be interpreted on the basis of intermediate strength exciton coupling, in which the electronic interaction is comparable to the van der Waals vibrational energies. The spectra are reasonably well described by two distorted adiabatic potential surfaces, which correspond to the two excitonic components of the origin system. A single Franck-Condon active intermolecular mode provides a reasonable description of the system, however the potentials have significant cubic and quartic contributions. Non-Born-Oppenheimer nuclear momentum coupling is present and intermodal (IVR) interactions are observed, even for intermolecular modes as low as v=1. The results are remarkably different from prior observations of excitonic structure in other systems, providing a detailed picture of coupling between electronic and intermolecular motion in a van der Waals dimer.

  12. Theoretical studies of transition metal dimers

    NASA Technical Reports Server (NTRS)

    Walch, Stephen P.; Bauschlicher, Charles W., Jr.

    1985-01-01

    The CASSCF approach was used to perform the MCSCF calculations for a number of transition metal dimers, including the Sc2, Ti2, Cr2, Cu2, TiV, Y2, Nb2, and Mo2 molecules; in addition, CASSCF/CI calculations were carried out for Sc2, Ti2, Cu2, and Y2. The CASSCF procedure is shown to provide a consistent set of calculations for these molecules, from which trends and a simple qualitative picture of the electronic structure may be derived. In particular, the calculations confirmed the ground states of the Sc2 and the TiV, and led to predictions for other molecules in this series. In addition to specific predictions, the study provides a simple qualitative picture of the bonding in these dimers.

  13. Fibrillar dimer formation of islet amyloid polypeptides

    SciTech Connect

    Chiu, Chi-cheng; de Pablo, Juan J.

    2015-05-08

    Amyloid deposits of human islet amyloid polypeptide (hIAPP), a 37-residue hormone co-produced with insulin, have been implicated in the development of type 2 diabetes. Residues 20 – 29 of hIAPP have been proposed to constitute the amyloidogenic core for the aggregation process, yet the segment is mostly unstructured in the mature fibril, according to solid-state NMR data. Here we use molecular simulations combined with bias-exchange metadynamics to characterize the conformational free energies of hIAPP fibrillar dimer and its derivative, pramlintide. We show that residues 20 – 29 are involved in an intermediate that exhibits transient β-sheets, consistent with recent experimental and simulation results. By comparing the aggregation of hIAPP and pramlintide, we illustrate the effects of proline residues on inhibition of the dimerization of IAPP. The mechanistic insights presented here could be useful for development of therapeutic inhibitors of hIAPP amyloid formation.

  14. Theoretical studies of transition metal dimers

    NASA Technical Reports Server (NTRS)

    Walch, Stephen P.; Bauschlicher, Charles W., Jr.

    1985-01-01

    The CASSCF approach was used to perform the MCSCF calculations for a number of transition metal dimers, including the Sc2, Ti2, Cr2, Cu2, TiV, Y2, Nb2, and Mo2 molecules; in addition, CASSCF/CI calculations were carried out for Sc2, Ti2, Cu2, and Y2. The CASSCF procedure is shown to provide a consistent set of calculations for these molecules, from which trends and a simple qualitative picture of the electronic structure may be derived. In particular, the calculations confirmed the ground states of the Sc2 and the TiV, and led to predictions for other molecules in this series. In addition to specific predictions, the study provides a simple qualitative picture of the bonding in these dimers.

  15. Repair of DNA-containing pyrimidine dimers

    SciTech Connect

    Grossman, L.; Caron, P.R.; Mazur, S.J.; Oh, E.Y.

    1988-08-01

    Ultraviolet light-induced pyrimidine dimers in DNA are recognized and repaired by a number of unique cellular surveillance systems. The most direct biochemical mechanism responding to this kind of genotoxicity involves direct photoreversal by flavin enzymes that specifically monomerize pyrimidine:pyrimidine dimers monophotonically in the presence of visible light. Incision reactions are catalyzed by a combined pyrimidine dimer DNA-glycosylase:apyrimidinic endonuclease found in some highly UV-resistant organisms. At a higher level of complexity, Escherichia coli has a uvr DNA repair system comprising the UvrA, UvrB, and UvrC proteins responsible for incision. There are several preincision steps governed by this pathway, which includes an ATP-dependent UvrA dimerization reaction required for UvrAB nucleoprotein formation. This complex formation driven by ATP binding is associated with localized topological unwinding of DNA. This same protein complex can catalyze an ATPase-dependent 5'----3'-directed strand displacement of D-loop DNA or short single strands annealed to a single-stranded circular or linear DNA. This putative translocational process is arrested when damaged sites are encountered. The complex is now primed for dual incision catalyzed by UvrC. The remainder of the repair process involves UvrD (helicase II) and DNA polymerase I for a coordinately controlled excision-resynthesis step accompanied by UvrABC turnover. Furthermore, it is proposed that levels of repair proteins can be regulated by proteolysis. UvrB is converted to truncated UvrB* by a stress-induced protease that also acts at similar sites on the E. coli Ada protein. Although UvrB* can bind with UvrA to DNA, it cannot participate in helicase or incision reactions. It is also a DNA-dependent ATPase.21 references.

  16. Dielectric relaxation in liquid crystalline dimers

    NASA Astrophysics Data System (ADS)

    Dunmur, D. A.; Luckhurst, G. R.; de la Fuente, M. R.; Diez, S.; Peréz Jubindo, M. A.

    2001-11-01

    Dielectric measurements are reported for liquid crystalline dimers consisting of two mesogenic groups joined through ether links by a flexible alkyl chain. Results are presented for the odd-symmetric dimer, α,ω-bis[(4-cyanobiphenyl)-4'-yloxy]undecane (BCB.O11), and the odd-asymmetric dimer, α-[(4-cyanobiphenyl)-4'-yloxy]-ω-(4-decylanilinebenzylidene-4'-oxy) nonane (CB.O9O.10). The real and imaginary parts of the electric permittivities of aligned samples were measured as functions of frequency over the range 102-109 Hz at temperatures throughout the nematic phase. Measurements were fitted as a function of frequency to the Havriliak-Negami function, and yielded relaxation times and dielectric strengths for the relaxations at each of the temperatures studied. The static dielectric anisotropy for both materials was positive. For BCB.O11, the parallel and perpendicular components of the permittivity exhibited one low frequency and one high frequency relaxation, while the parallel component of the permittivity for CB.O9O.10 showed three relaxations, which were well-separated in frequency. A generic model of liquid crystalline dimers based on mixtures of linear and bent conformers with the tetrahedral angle has been proposed [A. Ferrarini et al., Chem. Phys. Lett. 214, 409 (1993)]. This model is used to provide a qualitative interpretation of the dielectric measurements reported. To obtain a satisfactory explanation of the results, it is necessary to include additional conformers having either a hairpin shape or a bent shape with an angle of 180° minus the tetrahedral angle. The temperature dependence measured for the strengths of the dielectric relaxations is explained in terms of changes of the order parameter and changes in the relative probabilities of different shaped conformers.

  17. Ab initio torsional potentials in silole dimers

    SciTech Connect

    Yamaguchi, Yoichi; Yamabe, Tokio

    1996-01-05

    The potential barriers for the internal rotation of silole dimers are studied theoretically using the ab initio molecular orbital method at the RHF/6-31G** level of calculations. In 2,2{prime}-bisilole, it is found that the anti-conformation is the most stable structure in the ground state and that the potential barrier height for rotation over the perpendicular conformation is 3.3 kcal/mol. 21 refs., 4 figs., 2 tabs.

  18. Palmitoylated APP Forms Dimers, Cleaved by BACE1.

    PubMed

    Bhattacharyya, Raja; Fenn, Rebecca H; Barren, Cory; Tanzi, Rudolph E; Kovacs, Dora M

    2016-01-01

    A major rate-limiting step for Aβ generation and deposition in Alzheimer's disease brains is BACE1-mediated cleavage (β-cleavage) of the amyloid precursor protein (APP). We previously reported that APP undergoes palmitoylation at two cysteine residues (Cys186 and Cys187) in the E1-ectodomain. 8-10% of total APP is palmitoylated in vitro and in vivo. Palmitoylated APP (palAPP) shows greater preference for β-cleavage than total APP in detergent resistant lipid rafts. Protein palmitoylation is known to promote protein dimerization. Since dimerization of APP at its E1-ectodomain results in elevated BACE1-mediated cleavage of APP, we have now investigated whether palmitoylation of APP affects its dimerization and whether this leads to elevated β-cleavage of the protein. Here we report that over 90% of palAPP is dimerized while only ~20% of total APP forms dimers. PalAPP-dimers are predominantly cis-oriented while total APP dimerizes in both cis- and trans-orientation. PalAPP forms dimers 4.5-times more efficiently than total APP. Overexpression of the palmitoylating enzymes DHHC7 and DHHC21 that increase palAPP levels and Aβ release, also increased APP dimerization in cells. Conversely, inhibition of APP palmitoylation by pharmacological inhibitors reduced APP-dimerization in coimmunoprecipitation and FLIM/FRET assays. Finally, in vitro BACE1-activity assays demonstrate that palmitoylation-dependent dimerization of APP promotes β-cleavage of APP in lipid-rich detergent resistant cell membranes (DRMs), when compared to total APP. Most importantly, generation of sAPPβ-sAPPβ dimers is dependent on APP-palmitoylation while total sAPPβ generation is not. Since BACE1 shows preference for palAPP dimers over total APP, palAPP dimers may serve as novel targets for effective β-cleavage inhibitors of APP as opposed to BACE1 inhibitors.

  19. Palmitoylated APP Forms Dimers, Cleaved by BACE1

    PubMed Central

    Fenn, Rebecca H.; Barren, Cory; Tanzi, Rudolph E.; Kovacs, Dora M.

    2016-01-01

    A major rate-limiting step for Aβ generation and deposition in Alzheimer’s disease brains is BACE1-mediated cleavage (β-cleavage) of the amyloid precursor protein (APP). We previously reported that APP undergoes palmitoylation at two cysteine residues (Cys186 and Cys187) in the E1-ectodomain. 8–10% of total APP is palmitoylated in vitro and in vivo. Palmitoylated APP (palAPP) shows greater preference for β-cleavage than total APP in detergent resistant lipid rafts. Protein palmitoylation is known to promote protein dimerization. Since dimerization of APP at its E1-ectodomain results in elevated BACE1-mediated cleavage of APP, we have now investigated whether palmitoylation of APP affects its dimerization and whether this leads to elevated β-cleavage of the protein. Here we report that over 90% of palAPP is dimerized while only ~20% of total APP forms dimers. PalAPP-dimers are predominantly cis-oriented while total APP dimerizes in both cis- and trans-orientation. PalAPP forms dimers 4.5-times more efficiently than total APP. Overexpression of the palmitoylating enzymes DHHC7 and DHHC21 that increase palAPP levels and Aβ release, also increased APP dimerization in cells. Conversely, inhibition of APP palmitoylation by pharmacological inhibitors reduced APP-dimerization in coimmunoprecipitation and FLIM/FRET assays. Finally, in vitro BACE1-activity assays demonstrate that palmitoylation-dependent dimerization of APP promotes β-cleavage of APP in lipid-rich detergent resistant cell membranes (DRMs), when compared to total APP. Most importantly, generation of sAPPβ-sAPPβ dimers is dependent on APP-palmitoylation while total sAPPβ generation is not. Since BACE1 shows preference for palAPP dimers over total APP, palAPP dimers may serve as novel targets for effective β-cleavage inhibitors of APP as opposed to BACE1 inhibitors. PMID:27875558

  20. Sequestration of glucosinolates and iridoid glucosides in sawfly species of the genus Athalia and their role in defense against ants.

    PubMed

    Opitz, Sebastian E W; Jensen, Søren R; Müller, Caroline

    2010-02-01

    In this study, the larval sequestration abilities and defense effectiveness of four sawfly species of the genus Athalia (Hymenoptera: Tenthredinidae) that feed as larvae either on members of the Brassicaceae or Plantaginaceae were investigated. Brassicaceae are characterized by glucosinolates (GLSs), whereas Plantaginaceae contain iridoid glucosides (IGs) as characteristic secondary compounds. Athalia rosae and A. liberta feed on members of the Brassicaceae. Larvae of A. rosae sequester aromatic and aliphatic GLSs of Sinapis alba in their hemolymph, as shown previously, but no indolic GLSs; A. liberta larvae with a narrower host range sequester aliphatic as well as indolic GLSs from their host plant Alliaria petiolata. Larvae of A. circularis and A. cordata are specialized on members of the Plantaginaceae. Athalia circularis utilizes mainly Veronica beccabunga as host plant, whereas A. cordata feeds additionally on Plantago lanceolata. Both sawfly species sequester the IGs aucubin and catalpol. In V. beccabunga, catalpol esters and carboxylated IGs also occur. The high catalpol concentrations in hemolymph of A. circularis can only be explained by a metabolization of catalpol esters and subsequent uptake of the resulting catalpol. The carboxylated IGs of the plant are excreted. The IG-sequestering sawfly species are able to accumulate much higher glucoside concentrations in their hemolymph than the GLS-sequestering species, and the concentration of IGs in hemolymph increases constantly during larval development. The defensive effectiveness of hemolymph that contains GLSs or IGs and of the respective glucosides was tested in feeding-bioassays against a potential predator, the ant Myrmica rubra (Hymenoptera: Formicidae). Hemolymph of IG-sequestering cryptic A. cordata larvae has a higher deterrence potential than hemolymph of the GLS-sequestering conspicuous A. rosae larvae. The results show that glucoside sequestration is widespread in the genus Athalia, but that the

  1. Helicobacter pylori Cholesteryl α-Glucosides Contribute to Its Pathogenicity and Immune Response by Natural Killer T Cells

    PubMed Central

    Ito, Yuki; Vela, Jose Luis; Matsumura, Fumiko; Hoshino, Hitomi; Tyznik, Aaron; Lee, Heeseob; Girardi, Enrico; Zajonc, Dirk M.; Liddington, Robert; Kobayashi, Motohiro; Bao, Xingfeng; Bugaytsova, Jeanna; Borén, Thomas; Jin, Rongsheng; Zong, Yinong; Seeberger, Peter H.; Nakayama, Jun; Kronenberg, Mitchell; Fukuda, Minoru

    2013-01-01

    Approximately 10–15% of individuals infected with Helicobacter pylori will develop ulcer disease (gastric or duodenal ulcer), while most people infected with H. pylori will be asymptomatic. The majority of infected individuals remain asymptomatic partly due to the inhibition of synthesis of cholesteryl α-glucosides in H. pylori cell wall by α1,4-GlcNAc-capped mucin O-glycans, which are expressed in the deeper portion of gastric mucosa. However, it has not been determined how cholesteryl α-glucosyltransferase (αCgT), which forms cholesteryl α-glucosides, functions in the pathogenesis of H. pylori infection. Here, we show that the activity of αCgT from H. pylori clinical isolates is highly correlated with the degree of gastric atrophy. We investigated the role of cholesteryl α-glucosides in various aspects of the immune response. Phagocytosis and activation of dendritic cells were observed at similar degrees in the presence of wild-type H. pylori or variants harboring mutant forms of αCgT showing a range of enzymatic activity. However, cholesteryl α-glucosides were recognized by invariant natural killer T (iNKT) cells, eliciting an immune response in vitro and in vivo. Following inoculation of H. pylori harboring highly active αCgT into iNKT cell-deficient (Jα18−/−) or wild-type mice, bacterial recovery significantly increased in Jα18−/− compared to wild-type mice. Moreover, cytokine production characteristic of Th1 and Th2 cells dramatically decreased in Jα18−/− compared to wild-type mice. These findings demonstrate that cholesteryl α-glucosides play critical roles in H. pylori-mediated gastric inflammation and precancerous atrophic gastritis. PMID:24312443

  2. Mozambioside Is an Arabica-Specific Bitter-Tasting Furokaurane Glucoside in Coffee Beans.

    PubMed

    Lang, Roman; Klade, Stefan; Beusch, Anja; Dunkel, Andreas; Hofmann, Thomas

    2015-12-09

    Sensory-guided fractionation of a roasted coffee beverage revealed a highly polar, bitter-tasting subfraction, from which the furokaurane glucoside mozambioside was isolated and identified in its chemical structure by means of HDMS and NMR spectra. Sensory evaluation revealed a bitter taste recognition threshold of 60 (± 10) μmol/L. UPLC-HDMS quantitation of raw coffee beans showed that Arabica coffees contained 396-1188 nmol/g mozambioside, whereas only traces (<5 nmol/g) were detected in Robusta coffees, thus suggesting that mozambioside can be used as an analytical marker for Arabica coffee. Roasted Arabica contained a substantially reduced concentration (232 ± 37 nmol/g), indicating partial degradation of mozambioside during coffee roasting. Mozambioside was nearly quantitatively extracted into the aqueous brew during coffee-making (86-98%).

  3. Potential applications of glucosyltransferases in terpene glucoside production: impacts on the use of aroma and fragrance.

    PubMed

    Schwab, Wilfried; Fischer, Thilo C; Giri, Ashok; Wüst, Matthias

    2015-01-01

    The detection of glucoconjugated forms of monoterpene alcohols in rose petals in the late 1960s opened the new field of nonvolatile aroma precursors in flavor research. It is now well established that odorless glycosides represent a significant pool of aroma precursors in plants where they act as preformed but inactivated defense or attractive chemicals. Technical improvements in the separation and identification of plant secondary metabolites have provided a multitude of chemical structures, but functional characterization of glycosyltransferases that catalyze their formation lags behind. As technical efforts and costs for DNA sequencing dramatically dropped during the last decade, the number of plant genome sequences increased significantly, thus providing opportunities to functionally characterize the glycosyltransferase gene families in plants. These studies yielded the first glycosyltransferase genes that encode efficient biocatalysts for the production of monoterpene glucosides. They have applications in the food, feed, chemical, cosmetic, and pharmaceutical industries as slow release aroma chemicals.

  4. Synthesis, characterisation and antioxidant features of procyanidin B4 and malvidin-3-glucoside stearic acid derivatives.

    PubMed

    Cruz, Luis; Fernandes, Virgínia C; Araújo, Paula; Mateus, Nuno; de Freitas, Victor

    2015-05-01

    The acylation of procyanidin B4 with a saturated fatty acid chloride containing 18 carbon atoms was studied in order to obtain procyanidin B4 3-O-di-stearic acid conjugate. This compound was structurally characterised by mass spectrometry and 1D and 2D NMR techniques. Derivatization of malvidin-3-glucoside using stearoyl chloride in acetonitrile was also performed yielding mono-, di- and tri-stearic ester derivatives. The novel derivatives obtained revealed significant antioxidant activity, although lower than the respective precursors. However, the chemical modification of anthocyanins and procyanidins (water soluble pigments) to more lipophilic compounds has the advantage of increased bioavailability in biological matrices, and to potentiate their application in food matrices and cosmetic products. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Decyl glucoside as a corrosion inhibitor for magnesium-air battery

    NASA Astrophysics Data System (ADS)

    Deyab, M. A.

    2016-09-01

    In this research, the effects of decyl glucoside (DG) on the corrosion inhibition and battery performance of Mg-air battery have been investigated. Chemical and electrochemical techniques have been used to evaluate the corrosion rate and inhibitor efficiency. Mg surface has been characterized with scanning electron microscopy (SEM) and infrared spectroscopy (FTIR). A significant reduction in the corrosion rate of Mg in battery electrolyte (3.5% NaCl solution) has been observed in the presence of DG surfactant. Maximum inhibition efficiency (>94%) is achieved at critical micelle concentration of DG surfactant (CMC = 2.5 mM). The presence of DG surfactant increases the activation energy of the corrosion reaction. Physisorption mechanism has been suggested for the inhibition action of DG surfactant. The Mg-air battery containing DG surfactant offers higher operating voltage, discharge capacity and anodic utilization than in its absence.

  6. Rumpictuside A: Unusual 9,10-anthraquinone glucoside from Rumex pictus Forssk.

    PubMed

    El-Kashak, Walaa A; Elshamy, Abdelsamed I; Mohamed, Tarik A; El Gendy, Abd El-Nasser G; Saleh, Ibrahim A; Umeyama, Akemi

    2017-08-07

    A new 8-ionized hydroxylated 9,10-anthraquinone namely, 1-hydroxy-3-methyl-9,10-anthraquinone-6-O-β-D-glucopyranoside-8-olate (Rumpictuside A, 1) along with five known flavonoids, apigenin 7-O-β-D-glucoside (2), vitexin (3), quercetin 3-O-β-D-glucouronide (4), orientin (5), and isorientin (6) were isolated from Rumex pictus. The structures of isolated compounds were identified by the extensive spectroscopic techniques such as, UV, FT-IR, 1D, 2D NMR and HR-FAB-ESI-MS. The ionized hydroxyl group in the new anthraquinone (1) was rarely found for anthraquinone glycosides isolated from natural sources. All the isolated compounds were found inactive against influenza A virus infection. Compounds 2-6 exhibited significant antioxidant activity against DPPH and ABTS(+). The alcoholic extract exhibited moderate activity while the new anthraquinone 1 showed the lowest activity against both assays. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Jacaranone-derived glucosidic esters from Jacaranda glabra and their activity against Plasmodium falciparum.

    PubMed

    Gachet, M Salomé; Kunert, Olaf; Kaiser, Marcel; Brun, Reto; Muñoz, Ricardo A; Bauer, Rudolf; Schühly, Wolfgang

    2010-04-23

    In a survey of plants from Ecuador with antiprotozoal activity, Jacaranda glabra was found to show promising activity against the Plasmodium falciparum K1 strain. Subsequently, activity-guided isolation of the dichloromethane extract from the leaves of J. glabra afforded four new phenylethanoid glucosides containing jacaranone-type moieties (1-4), named jacaglabrosides A-D. Their chemical structures were identified using NMR spectroscopy and MS techniques. The compounds were found to be active in vitro against the P. falciparum K1 strain (IC(50) 1, 1.02; 2, 0.56; 3, 0.56; and 4, 0.55 microg/mL) and generally possessed a low cytotoxicity toward L-6 cells, with the exception of compound 1 (IC(50) 1, 8.3; 2, >90; 3, 87; and 4, 85 microg/mL).

  8. Synthesis and antimicrobial activity of 6-triazolo-6-deoxy eugenol glucosides.

    PubMed

    de Souza, Thiago Belarmino; Raimundo, Paulo Otávio Botelho; Andrade, Saulo Fernandes; Hipólito, Taciane Maira Magalhães; Silva, Naiara Chaves; Dias, Amanda Latercia Tranches; Ikegaki, Masaharu; Rocha, Raissa Prado; Coelho, Luiz Felipe Leomil; Veloso, Marcia Paranho; Carvalho, Diogo Teixeira; Dias, Danielle Ferreira

    2015-06-17

    A new series of 1,2,3-triazole eugenol glucosides were synthesized. The new compound structures were confirmed by MS, (1)H NMR and (13)C NMR. All of the synthesized compounds were screened for antimicrobial and cytotoxic activity. Five compounds exerted significant activity against the Gram-negative bacteria Salmonella typhimurium with low IC50 values (49.73-68.53 μΜ), and seven compounds were active against the Gram-positive bacteria Micrococcus luteus (42.89-210.94 μM). In vitro cytotoxicity on mouse spleen cells was also evaluated. One compound bearing a phenyl substituent at the triazole ring showed good activity against Salmonella typhimurium (49.73 μM) and low toxicity to normal cells (CC50=157.83 μM). Thus, the compounds herein can be considered for further modification for improving their antibacterial activity or obtaining novel antibacterial drug candidates.

  9. Benzoxazinoids-cyclic hydroxamic acids, lactams and their corresponding glucosides in the genus Aphelandra (Acanthaceae).

    PubMed

    Baumeler, A; Hesse, M; Werner, C

    2000-01-01

    An improved method of sample preparation and simultaneous HPLC separation was developed that allowed the separation of 2,4-dihydroxy-1,4-benzoxazine-3(4H)-one (DIBOA), 2,4-dihydroxy-7-methoxy-1,4-benzoxazine-3(4H)-one (DIMBOA), 2-hydroxy-1,4-benzoxazine-3(2H)-one (HBOA), 2-hydroxy-7-methoxy-1,4-benzoxazine-3(2H)-one (HMBOA) and their corresponding glucosides as well as the benzoxazolinones BOA and MBOA. The amount and distribution of these compounds was determined in the roots of Aphelandra squarrosa and A. fuscopunctata plants. There is a significant difference in the amount and distribution of this substance class in the two species analyzed. The results are discussed in relation to their function as defence compounds and allelochemicals.

  10. Phenylanthraquinones and flavone-C-glucosides from the disjunct Bulbinella in New Zealand.

    PubMed

    Richardson, Alistair T B; Lord, Janice M; Perry, Nigel B

    2017-02-01

    The genera Bulbine, Bulbinella and Kniphofia produce phenylanthraquinones and are mostly found in southern Africa, although a disjunct group of Bulbinella species endemic to New Zealand also contain phenylanthraquinones as reported herein. The sub-Antarctic megaherb B. rossii yielded sulphated phenylanthraquinones, including a phenylanthraquinone found to carry a sulphated glycoside substituent, 4'-O-demethylknipholone-4'-β-D-xylopyranosyl-3″-sulphate. A sensitive HPLC method was used to analyse 5 of the 6 New Zealand Bulbinella species, all of which contained phenylanthraquinones. Leaves and roots had different profiles, but species were not distinct. Roots were rich in sulphated and free phenylanthraquinones (0.27 ± 0.09% dry wt), whereas leaves typically only contained free knipholone (0.14 ± 0.01%). Localisation of phenylanthraquinones to the stele and peel was observed in roots. Two flavone-C-glucosides were found in leaves of Bulbinella.

  11. Sesquiterpene lactone glucosides and alkyl glycosides from the fruit of cumin.

    PubMed

    Takayanagi, Tomomi; Ishikawa, Toru; Kitajima, Junichi

    2003-06-01

    From the polar portion of the methanolic extract of cumin (fruit of Cuminum cyminum L.), two sesquiterpenoid glucosides, cuminoside A and B, and two alkyl glycosides were isolated together with five known compounds. Their structures were established as (1S,5S,6S,10S)-10-hydroxyguaia-3,7(11)-dien-12,6-olide beta-D-glucopyranoside, (1R,5R,6S,7S,9S,10R,11R)-1,9-dihydroxyeudesm-3-en-12,6-olide 9-O-beta-D-glucopyranoside, methyl beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyranoside and ethane-1,2-diol 1-O-beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyranoside, respectively.

  12. Occurrence of Deoxynivalenol and Deoxynivalenol-3-glucoside in Hard Red Spring Wheat Grown in the USA

    PubMed Central

    Simsek, Senay; Ovando-Martínez, Maribel; Ozsisli, Bahri; Whitney, Kristin; Ohm, Jae-Bom

    2013-01-01

    Deoxynivalenol (DON) is a mycotoxin found in wheat that is infected with Fusarium fungus. DON may also be converted to a type of “masked mycotoxin”, named deoxynivalenol-3-glucoside (D3G), as a result of detoxification of the plant. In this study, DON and D3G were measured using gas chromatographic (GC) and liquid chromatography-mass spectrometry (LC-MS) in wheat samples collected during 2011 and 2012 in the USA. Results indicate that the growing region had a significant effect on the DON and D3G (p < 0.0001). There was a positive correlation between both methods (GC and LC-MS) used for determination of DON content. DON showed a significant and positive correlation with D3G during 2011. Overall, DON production had an effect on D3G content and kernel damage, and was dependent on environmental conditions during Fusarium infection. PMID:24351720

  13. Occurrence of deoxynivalenol and deoxynivalenol-3-glucoside in hard red spring wheat grown in the USA.

    PubMed

    Simsek, Senay; Ovando-Martínez, Maribel; Ozsisli, Bahri; Whitney, Kristin; Ohm, Jae-Bom

    2013-12-18

    Deoxynivalenol (DON) is a mycotoxin found in wheat that is infected with Fusarium fungus. DON may also be converted to a type of "masked mycotoxin", named deoxynivalenol-3-glucoside (D3G), as a result of detoxification of the plant. In this study, DON and D3G were measured using gas chromatographic (GC) and liquid chromatography-mass spectrometry (LC-MS) in wheat samples collected during 2011 and 2012 in the USA. Results indicate that the growing region had a significant effect on the DON and D3G (p < 0.0001). There was a positive correlation between both methods (GC and LC-MS) used for determination of DON content. DON showed a significant and positive correlation with D3G during 2011. Overall, DON production had an effect on D3G content and kernel damage, and was dependent on environmental conditions during Fusarium infection.

  14. Isolation of new flavan-3-ol and lignan glucoside from Loropetalum chinense and their antimicrobial activities.

    PubMed

    Zhang, Qinghua; Fan, Dan; Xiong, Bingjian; Kong, Lingbao; Zhu, Xiangdong

    2013-10-01

    Phytochemical and antimicrobial activity study on the ethanol extract of the leaves and stems of Loropetalum chinense led to the isolation of a new flavan-3-ol compounds, 8-[1-(3,4-dihydroxyphenyl)-3-methoxy-3-oxopropyl]-catechin (loropetaliside A) (1) and a new lignan glucoside, 1-(5-hydroxy-3-methoxyphenyl)-2-(2-β-glucopyranosyl-4-hydroxy-5-(1-(E)propen-3-ol)-phenyl)-propane-3-ol (loropetaliside B) (3) and several known compounds manglieside D (2), quercetin (4), kaempferol-3-O-D-glucopyranoside (5), quercetin-3-O-β-L-rhamnoside (6) and tiliroside (7). Their structures were elucidated on the basis of extensive spectroscopic analysis.

  15. Dimer monomer transition and dimer re-formation play important role for ATM cellular function during DNA repair

    SciTech Connect

    Du, Fengxia; Zhang, Minjie; Li, Xiaohua; Yang, Caiyun; Meng, Hao; Wang, Dong; Chang, Shuang; Xu, Ye; Price, Brendan; Sun, Yingli

    2014-10-03

    Highlights: • ATM phosphorylates the opposite strand of the dimer in response to DNA damage. • The PETPVFRLT box of ATM plays a key role in its dimer dissociation in DNA repair. • The dephosphorylation of ATM is critical for dimer re-formation after DNA repair. - Abstract: The ATM protein kinase, is a serine/threonine protein kinase that is recruited and activated by DNA double-strand breaks, mediates responses to ionizing radiation in mammalian cells. Here we show that ATM is held inactive in unirradiated cells as a dimer and phosphorylates the opposite strand of the dimer in response to DNA damage. Cellular irradiation induces rapid intermolecular autophosphorylation of serine 1981 that causes dimer dissociation and initiates cellular ATM kinase activity. ATM cannot phosphorylate the substrates when it could not undergo dimer monomer transition. After DNA repair, the active monomer will undergo dephosphorylation to form dimer again and dephosphorylation is critical for dimer re-formation. Our work reveals novel function of ATM dimer monomer transition and explains why ATM dimer monomer transition plays such important role for ATM cellular activity during DNA repair.

  16. Resveratrol glucoside (Piceid) synthesis in seeds of transgenic oilseed rape (Brassica napus L.).

    PubMed

    Hüsken, Alexandra; Baumert, Alfred; Milkowski, Carsten; Becker, Heiko C; Strack, Dieter; Möllers, Christian

    2005-11-01

    Resveratrol is a phytoalexin produced in various plants like wine, peanut or pine in response to fungal infection or UV irradiation, but it is absent in members of the Brassicaceae. Moreover, resveratrol and its glucoside (piceid) are considered to have beneficial effects on human health, known to reduce heart disease, arteriosclerosis and cancer mortality. Therefore, the introduction of the gene encoding stilbene synthase for resveratrol production in rapeseed is a tempting approach to improve the quality of rapeseed products. The stilbene synthase gene isolated from grapevine (Vitis vinifera L.) was cloned under control of the seed-specific napin promotor and introduced into rapeseed (Brassica napus L.) by Agrobacterium-mediated co-transformation together with a ds-RNA-interference construct deduced from the sequence of the key enzyme for sinapate ester biosynthesis, UDP-glucose:sinapate glucosyltransferase (BnSGT1), assuming that the suppression of the sinapate ester biosynthesis may increase the resveratrol production in seeds through the increased availability of the precursor 4-coumarate. Resveratrol glucoside (piceid) was produced at levels up to 361 microg/g in the seeds of the primary transformants. This value exceeded by far piceid amounts reported from B. napus expressing VST1 in the wild type sinapine background. There was no significant difference in other important agronomic traits, like oil, protein, fatty acid and glucosinolate content in comparison to the control plants. In the third seed generation, up to 616 microg/g piceid was found in the seeds of a homozygous T3-plant with a single transgene copy integrated. The sinapate ester content in this homozygous T3-plant was reduced from 7.43 to 2.40 mg/g. These results demonstrate how the creation of a novel metabolic sink could divert the synthesis towards the production of piceid rather than sinapate ester, thereby increasing the value of oilseed products.

  17. Triacylated cyanidin 3-(3X-glucosylsambubioside)-5-glucosides from the flowers of Malcolmia maritima.

    PubMed

    Tatsuzawa, Fumi; Saito, Norio; Toki, Kenjiro; Shinoda, Koichi; Shigihara, Atsushi; Honda, Toshio

    2008-02-01

    Three acylated cyanidin 3-(3(X)-glucosylsambubioside)-5-glucosides (1-3) and one non-acylated cyanidin 3-(3(X)-glucosylsambubioside)-5-glucoside (4) were isolated from the purple-violet or violet flowers and purple stems of Malcolmia maritima (L.) R. Br (the Cruciferae), and their structures were determined by chemical and spectroscopic methods. In the flowers of this plant, pigment 1 was determined to be cyanidin 3-O-[2-O-(2-O-(trans-sinapoyl)-3-O-(beta-D-glucopyranosyl)-beta-D-xylopyranosyl)-6-O-(trans-p-coumaroyl)-beta-D-glucopyranoside]-5-O-[6-O-(malonyl)-(beta-D-glucopyranoside) as a major pigment, and a minor pigment 2 was determined to be the cis-p-coumaroyl isomer of pigment 1. In the stems, pigment 3 was determined to be cyanidin 3-O-[2-O-(2-O-(trans-sinapoyl)-3-O-(beta-D-glucopyranosyl)-beta-D-xylopyranosyl)-6-O-(trans-p-coumaroyl)-beta-d-glucopyranoside]-5-O-(beta-D-glucopyranoside) as a major anthocyanin, and also a non-acylated anthocyanin, cyanidin 3-O-[2-O-(3-O-(beta-D-glucopyranosyl)-beta-D-xylopyranosyl)-beta-D-glucopyranoside]-5-O-(beta-D-glucopyranoside) was determined to be a minor pigment (pigment 4). In this study, it was established that the acylation-enzymes of malonic acid has important roles for the acylation of 5-glucose residues of these anthocyanins in the flower-tissues of M. maritima; however, the similar enzymatic reactions seemed to be inhibited or lacking in the stem-tissues.

  18. Molecular cloning and characterization of genistein 4'-O-glucoside specific glycosyltransferase from Bacopa monniera.

    PubMed

    Ruby; Santosh Kumar, R J; Vishwakarma, Rishi K; Singh, Somesh; Khan, Bashir M

    2014-07-01

    Health related benefits of isoflavones such as genistein are well known. Glycosylation of genistein yields different glycosides like genistein 7-O-glycoside (genistin) and genistein 4'-O-glycoside (sophoricoside). This is the first report on isolation, cloning and functional characterization of a glycosyltransferase specific for genistein 4'-O-glucoside from Bacopa monniera, an important Indian medicinal herb. The glycosyltransferase from B. monniera (UGT74W1) showed 49% identity at amino acid level with the glycosyltransferases from Lycium barbarum. The UGT74W1 sequence contained all the conserved motifs present in plant glycosyltransferases. UGT74W1 was cloned in pET-30b (+) expression vector and transformed into E. coli. The molecular mass of over expressed protein was found to be around 52 kDa. Functional characterization of the enzyme was performed using different substrates. Product analysis was done using LC-MS and HPLC, which confirmed its specificity for genistein 4'-O-glucoside. Immuno-localization studies of the UGT74W1 showed its localization in the vascular bundle. Spatio-temporal expression studies under normal and stressed conditions were also performed. The control B. monniera plant showed maximum expression of UGT74W1 in leaves followed by roots and stem. Salicylic acid treatment causes almost tenfold increase in UGT74W1 expression in roots, while leaves and stem showed decrease in expression. Since salicylic acid is generated at the time of injury or wound caused by pathogens, this increase in UGT74W1 expression under salicylic acid stress might point towards its role in defense mechanism.

  19. Cyanidin-3-O-glucoside: Physical-Chemistry, Foodomics and Health Effects.

    PubMed

    Olivas-Aguirre, Francisco J; Rodrigo-García, Joaquín; Martínez-Ruiz, Nina Del R; Cárdenas-Robles, Arely I; Mendoza-Díaz, Sandra O; Álvarez-Parrilla, Emilio; González-Aguilar, Gustavo A; de la Rosa, Laura A; Ramos-Jiménez, Arnulfo; Wall-Medrano, Abraham

    2016-09-21

    Anthocyanins (ACNs) are plant secondary metabolites from the flavonoid family. Red to blue fruits are major dietary sources of ACNs (up to 1 g/100 g FW), being cyanidin-3-O-glucoside (Cy3G) one of the most widely distributed. Cy3G confers a red hue to fruits, but its content in raspberries and strawberries is low. It has a good radical scavenging capacity (RSC) against superoxide but not hydroxyl radicals, and its oxidative potential is pH-dependent (58 mV/pH unit). After intake, Cy3G can be metabolized (phases I, II) by oral epithelial cells, absorbed by the gastric epithelium (1%-10%) and it is gut-transformed (phase II & microbial metabolism), reaching the bloodstream (<1%) and urine (about 0.02%) in low amounts. In humans and Caco-2 cells, Cy3G's major metabolites are protocatechuic acid and phloroglucinaldehyde which are also subjected to entero-hepatic recycling, although caffeic acid and peonidin-3-glucoside seem to be strictly produced in the large bowel and renal tissues. Solid evidence supports Cy3G's bioactivity as DNA-RSC, gastro protective, anti-inflammatory, anti-thrombotic chemo-preventive and as an epigenetic factor, exerting protection against Helicobacter pylori infection, age-related diseases, type 2 diabetes, cardiovascular disease, metabolic syndrome and oral cancer. Most relevant mechanisms include RSC, epigenetic action, competitive protein-binding and enzyme inhibition. These and other novel aspects on Cy3G's physical-chemistry, foodomics, and health effects are discussed.

  20. The open Bose-Hubbard dimer

    NASA Astrophysics Data System (ADS)

    Pudlik, Tadeusz

    This dissertation discusses a number of theoretical models of coupled bosonic modes, all closely related to the Bose-Hubbard dimer. In studying these models, we will repeatedly return to two unifying themes: the classical structure underlying quantum dynamics and the impact of weakly coupling a system to an environment. Or, more succinctly, semiclassical methods and open quantum systems. Our primary motivation for studying models such as the Bose-Hubbard is their relevance to ongoing ultracold atom experiments. We review these experiments, derive the Bose-Hubbard model in their context and briefly discuss its limitations in the first half of Chapter 1. In its second half, we review the theory of open quantum systems and the master equation description of the dissipative Bose-Hubbard model. This opening chapter constitutes a survey of existing results, rather than original work. In Chapter 2, we turn to the mean-field limit of the Bose-Hubbard model. After reviewing the striking localization phenomena predicted by the mean-field (and confirmed by experiment), we identify the first corrections to this picture for the dimer. The most interesting of these is the dynamical tunneling between the self-trapping points of the mean-field. We derive an accurate analytical expression for the tunneling rate using semiclassical techniques. We continue studying the dynamics near the self-trapping fixed points in Chapter 3, focusing on corrections to the mean-field that arise at larger nonlinearities and on shorter time scales than dynamical tunneling. We study the impact of dissipation on coherence and entanglement near the fixed points, and explain it in terms of the structure of the classical phase space. The last chapter of the dissertation is also devoted to a dissipative bosonic dimer model, but one arising in a very different physical context. Abandoning optical lattices, we consider the problem of formulating a quantum model of operation of the cylindrical anode magnetron

  1. Surface-subsurface model for a dimer-dimer catalytic reaction: a Monte Carlo simulation study

    NASA Astrophysics Data System (ADS)

    Khan, K. M.; Albano, E. V.

    2002-02-01

    The surface-subsurface model for a dimer-dimer reaction of the type A2 + 2B2→2AB2 has been studied through Monte Carlo simulation via a model based on the lattice gas non-thermal Langmuir-Hinshelwood mechanism, which involves the precursor motion of the B2 molecule. The motion of precursors is considered on the surface as well as in the subsurface. The most interesting feature of this model is that it yields a steady reactive window, which is separated by continuous and discontinuous irreversible phase transitions. The phase diagram is qualitatively similar to the well known Ziff, Gulari and Barshad (ZGB) model. The width of the window depends upon the mobility of precursors. The continuous transition disappears when the mobility of the surface precursors is extended to the third-nearest neighbourhood. The dependence of production rate on partial pressure of B2 dimer is predicted by simple mathematical equations in our model.

  2. Analysis of SecA Dimerization in Solution

    PubMed Central

    2015-01-01

    The Sec pathway mediates translocation of protein across the inner membrane of bacteria. SecA is a motor protein that drives translocation of preprotein through the SecYEG channel. SecA reversibly dimerizes under physiological conditions, but different dimer interfaces have been observed in SecA crystal structures. Here, we have used biophysical approaches to address the nature of the SecA dimer that exists in solution. We have taken advantage of the extreme salt sensitivity of SecA dimerization to compare the rates of hydrogen–deuterium exchange of the monomer and dimer and have analyzed the effects of single-alanine substitutions on dimerization affinity. Our results support the antiparallel dimer arrangement observed in one of the crystal structures of Bacillus subtilis SecA. Additional residues lying within the preprotein binding domain and the C-terminus are also protected from exchange upon dimerization, indicating linkage to a conformational transition of the preprotein binding domain from an open to a closed state. In agreement with this interpretation, normal mode analysis demonstrates that the SecA dimer interface influences the global dynamics of SecA such that dimerization stabilizes the closed conformation. PMID:24786965

  3. Modulation of ceramide synthase activity via dimerization.

    PubMed

    Laviad, Elad L; Kelly, Samuel; Merrill, Alfred H; Futerman, Anthony H

    2012-06-15

    Ceramide, the backbone of all sphingolipids, is synthesized by a family of ceramide synthases (CerS) that each use acyl-CoAs of defined chain length for N-acylation of the sphingoid long chain base. CerS mRNA expression and enzymatic activity do not always correlate with the sphingolipid acyl chain composition of a particular tissue, suggesting post-translational mechanism(s) of regulation of CerS activity. We now demonstrate that CerS activity can be modulated by dimer formation. Under suitable conditions, high M(r) CerS complexes can be detected by Western blotting, and various CerS co-immunoprecipitate. CerS5 activity is inhibited in a dominant-negative fashion by co-expression with catalytically inactive CerS5, and CerS2 activity is enhanced by co-expression with a catalytically active form of CerS5 or CerS6. In a constitutive heterodimer comprising CerS5 and CerS2, the activity of CerS2 depends on the catalytic activity of CerS5. Finally, CerS dimers are formed upon rapid stimulation of ceramide synthesis by curcumin. Together, these data demonstrate that ceramide synthesis can be regulated by the formation of CerS dimers and suggest a novel way to generate the acyl chain composition of ceramide (and downstream sphingolipids), which may depend on the interaction of CerS with each other.

  4. Specific Glucoside Transporters Influence Septal Structure and Function in the Filamentous, Heterocyst-Forming Cyanobacterium Anabaena sp. Strain PCC 7120.

    PubMed

    Nieves-Morión, Mercedes; Lechno-Yossef, Sigal; López-Igual, Rocío; Frías, José E; Mariscal, Vicente; Nürnberg, Dennis J; Mullineaux, Conrad W; Wolk, C Peter; Flores, Enrique

    2017-04-01

    When deprived of combined nitrogen, some filamentous cyanobacteria contain two cell types: vegetative cells that fix CO2 through oxygenic photosynthesis and heterocysts that are specialized in N2 fixation. In the diazotrophic filament, the vegetative cells provide the heterocysts with reduced carbon (mainly in the form of sucrose) and heterocysts provide the vegetative cells with combined nitrogen. Septal junctions traverse peptidoglycan through structures known as nanopores and appear to mediate intercellular molecular transfer that can be traced with fluorescent markers, including the sucrose analog esculin (a coumarin glucoside) that is incorporated into the cells. Uptake of esculin by the model heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 was inhibited by the α-glucosides sucrose and maltose. Analysis of Anabaena mutants identified components of three glucoside transporters that move esculin into the cells: GlsC (Alr4781) and GlsP (All0261) are an ATP-binding subunit and a permease subunit of two different ABC transporters, respectively, and HepP (All1711) is a major facilitator superfamily (MFS) protein that was shown previously to be involved in formation of the heterocyst envelope. Transfer of fluorescent markers (especially calcein) between vegetative cells of Anabaena was impaired by mutation of glucoside transporter genes. GlsP and HepP interact in bacterial two-hybrid assays with the septal junction-related protein SepJ, and GlsC was found to be necessary for the formation of a normal number of septal peptidoglycan nanopores and for normal subcellular localization of SepJ. Therefore, beyond their possible role in nutrient uptake in Anabaena, glucoside transporters influence the structure and function of septal junctions.IMPORTANCE Heterocyst-forming cyanobacteria have the ability to perform oxygenic photosynthesis and to assimilate atmospheric CO2 and N2 These organisms grow as filaments that fix these gases specifically in vegetative

  5. Specific Glucoside Transporters Influence Septal Structure and Function in the Filamentous, Heterocyst-Forming Cyanobacterium Anabaena sp. Strain PCC 7120

    PubMed Central

    Nieves-Morión, Mercedes; Lechno-Yossef, Sigal; López-Igual, Rocío; Frías, José E.; Mariscal, Vicente; Nürnberg, Dennis J.; Mullineaux, Conrad W.; Wolk, C. Peter

    2017-01-01

    ABSTRACT When deprived of combined nitrogen, some filamentous cyanobacteria contain two cell types: vegetative cells that fix CO2 through oxygenic photosynthesis and heterocysts that are specialized in N2 fixation. In the diazotrophic filament, the vegetative cells provide the heterocysts with reduced carbon (mainly in the form of sucrose) and heterocysts provide the vegetative cells with combined nitrogen. Septal junctions traverse peptidoglycan through structures known as nanopores and appear to mediate intercellular molecular transfer that can be traced with fluorescent markers, including the sucrose analog esculin (a coumarin glucoside) that is incorporated into the cells. Uptake of esculin by the model heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 was inhibited by the α-glucosides sucrose and maltose. Analysis of Anabaena mutants identified components of three glucoside transporters that move esculin into the cells: GlsC (Alr4781) and GlsP (All0261) are an ATP-binding subunit and a permease subunit of two different ABC transporters, respectively, and HepP (All1711) is a major facilitator superfamily (MFS) protein that was shown previously to be involved in formation of the heterocyst envelope. Transfer of fluorescent markers (especially calcein) between vegetative cells of Anabaena was impaired by mutation of glucoside transporter genes. GlsP and HepP interact in bacterial two-hybrid assays with the septal junction-related protein SepJ, and GlsC was found to be necessary for the formation of a normal number of septal peptidoglycan nanopores and for normal subcellular localization of SepJ. Therefore, beyond their possible role in nutrient uptake in Anabaena, glucoside transporters influence the structure and function of septal junctions. IMPORTANCE Heterocyst-forming cyanobacteria have the ability to perform oxygenic photosynthesis and to assimilate atmospheric CO2 and N2. These organisms grow as filaments that fix these gases specifically in

  6. Identification of rice β-glucosidase with high hydrolytic activity towards salicylic acid β-D-glucoside.

    PubMed

    Himeno, Nami; Saburi, Wataru; Wakuta, Shinji; Takeda, Ryosuke; Matsuura, Hideyuki; Nabeta, Kensuke; Sansenya, Sompong; Ketudat Cairns, James R; Mori, Haruhide; Imai, Ryozo; Matsui, Hirokazu

    2013-01-01

    β-Glucosidases (EC 3.2.1.21) split β-glucosidic linkages at the non-reducing end of glucosides and oligosaccharides to release β-D-glucose. One of the important functions of plant β-glucosidase is deglucosylation of inactive glucosides of phytohormones to regulate levels of active hormones. Tuberonic acid is a jasmonate-related compound that shows tuber-inducing activity in the potato. We have identified two enzymes, OsTAGG1 and OsTAGG2, that have hydrolytic activity towards tuberonic acid β-D-glucoside in rice (Oryza sativa L.). The expression of OsTAGG2 is upregulated by wounding and by methyl jasmonate, suggesting that this isozyme is involved in responses to biotic stresses and wounding, but the physiological substrate of OsTAGG2 remains ambiguous. In this study, we produced recombinant OsTAGG2 in Pichia pastoris (rOsTAGG2P), and investigated its substrate specificity in detail. From 1 L of culture medium, 2.1 mg of purified recombinant enzyme was obtained by ammonium sulfate precipitation and Ni-chelating column chromatography. The specific activity of rOsTAGG2P (182 U/mg) was close to that of the native enzyme (171 U/mg), unlike recombinant OsTAGG2 produced in Escherichia coli, which had approximately 3-fold lower specific activity than the native enzyme. The optimum pH and temperature for rOsTAGG2P were pH 3.4 and 60 °C. After pH and heat treatments, the enzyme retained its original activity in a pH range of 3.4-9.8 and below 55 °C. Native OsTAGG2 and rOsTAGG2P showed 4.5-4.7-fold higher activities towards salicylic acid β-D-glucoside, an inactive storage-form of salicylic acid, than towards tuberonic acid β-D-glucoside (TAG), although OsTAGG2 was originally isolated from rice based on TAG-hydrolytic activity.

  7. Graded-index optical dimer formed by optical force

    DOE PAGES

    Akbarzadeh, Alireza; Koschny, Thomas; Kafesaki, Maria; ...

    2016-05-30

    We propose an optical dimer formed from two spherical lenses bound by the pressure that light exerts on matter. With the help of the method of force tracing, we find the required graded-index profiles of the lenses for the existence of the dimer. We study the dynamics of the opto-mechanical interaction of lenses under the illumination of collimated light beams and quantitatively validate the performance of the proposed dimer. We also examine the stability of the dimer due to the lateral misalignments and we show how restoring forces bring the dimer into lateral equilibrium. The dimer can be employed inmore » various practical applications such as optical manipulation, sensing and imaging.« less

  8. Metal enhanced fluorescence of Ag-nanoshell dimer

    NASA Astrophysics Data System (ADS)

    Liaw, Jiunn-Woei; Chen, Huang-Chih; Chen, Bae-Renn; Kuo, Mao-Kuen

    2014-04-01

    The plasmon modes of Ag-nanoshell dimer on metal enhanced fluorescence (MEF) are studied theoretically. The amplified excitation rate of a dimer (two identical Ag nanoshells) illuminated by a plane wave for exciting a molecule located at the gap center is calculated. Subsequently, the apparent quantum yield of the emission of the excited molecule affected by the dimer is investigated. The multiple multipole method is used for the both simulations. Finally, the enhancement factor of the dimer on the overall photoluminescence of the molecule in terms of the two parameters is evaluated. Our results show that Ag-nanoshell dimer is a dual-band photoluminescence enhancer for MEF at the bonding dipole and quadrupole modes. The former is broadband, and the latter narrowband. Both bands depend on the gap size. Moreover, the average enhancement factor of Ag-nanoshell dimer for MEF with a Stokes shift is discussed.

  9. Caffeine dimerization: effects of sugar, salts, and water structure.

    PubMed

    Shimizu, Seishi

    2015-10-01

    Sugars and salts strongly affect the dimerization of caffeine in water. Such a change of dimerization, considered to be crucial for bitter taste suppression, has long been rationalized by the change of "water structure" induced by the additives; "kosmotropic" (water structure enhancing) salts and sugars promote dimerization, whereas "chaotropic" (water structure breaking) salts suppress dimerization. Based on statistical thermodynamics, here we challenge this consensus; we combine the rigorous Kirkwood-Buff theory of solution with the classical isodesmic model of caffeine association. Instead of the change of water structure, we show that the enhancement of caffeine dimerization is due to the exclusion of additives from caffeine, and that the weakening of dimerization is due to the binding of additives on caffeine.

  10. Graded-index optical dimer formed by optical force

    DOE PAGES

    Akbarzadeh, Alireza; Koschny, Thomas; Kafesaki, Maria; ...

    2016-05-30

    We propose an optical dimer formed from two spherical lenses bound by the pressure that light exerts on matter. With the help of the method of force tracing, we find the required graded-index profiles of the lenses for the existence of the dimer. We study the dynamics of the opto-mechanical interaction of lenses under the illumination of collimated light beams and quantitatively validate the performance of the proposed dimer. We also examine the stability of the dimer due to the lateral misalignments and we show how restoring forces bring the dimer into lateral equilibrium. The dimer can be employed inmore » various practical applications such as optical manipulation, sensing and imaging.« less

  11. Computational reference data for the photochemistry of cyclobutane pyrimidine dimers.

    PubMed

    Barbatti, Mario

    2014-10-20

    The cis-syn cyclobutane pyrimidine dimer is one of the major classes of carcinogenic UV-induced DNA photoproducts. In this work, diverse high-level quantum-chemical methods were used to determine the spectroscopic properties of neutral (singlet and triplet) and charged (cation and anion) species of thymine dimers. Maps of potential energy, charge distribution, electron affinity, and ionization potential of the thymidine dimers were computed along the two dimerization coordinates for neutral and charged species, as well as for the singlet excited state. This set of data aims at providing consistent results computed with the same methods as for photodamage and repair. Based on these results, several different photo-, heat-, and charge-induced mechanisms of dimerization and repair are characterized and discussed. Additionally, a new stable dimer with methylmethylidene-hexahydropyrimidine structure was found in the S0 state. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Light-induced Changes in the Dimerization Interface of Bacteriophytochromes*

    PubMed Central

    Takala, Heikki; Björling, Alexander; Linna, Marko; Westenhoff, Sebastian; Ihalainen, Janne A.

    2015-01-01

    Phytochromes are dimeric photoreceptor proteins that sense red light levels in plants, fungi, and bacteria. The proteins are structurally divided into a light-sensing photosensory module consisting of PAS, GAF, and PHY domains and a signaling output module, which in bacteriophytochromes typically is a histidine kinase (HK) domain. Existing structural data suggest that two dimerization interfaces exist between the GAF and HK domains, but their functional roles remain unclear. Using mutational, biochemical, and computational analyses of the Deinococcus radiodurans phytochrome, we demonstrate that two dimerization interfaces between sister GAF and HK domains stabilize the dimer with approximately equal contributions. The existence of both dimerization interfaces is critical for thermal reversion back to the resting state. We also find that a mutant in which the interactions between the GAF domains were removed monomerizes under red light. This implies that the interactions between the HK domains are significantly altered by photoconversion. The results suggest functional importance of the dimerization interfaces in bacteriophytochromes. PMID:25971964

  13. Graded-index optical dimer formed by optical force

    SciTech Connect

    Akbarzadeh, Alireza; Koschny, Thomas; Kafesaki, Maria; Economou, Eleftherios N.; Soukoulis, Costas M.

    2016-05-30

    We propose an optical dimer formed from two spherical lenses bound by the pressure that light exerts on matter. With the help of the method of force tracing, we find the required graded-index profiles of the lenses for the existence of the dimer. We study the dynamics of the opto-mechanical interaction of lenses under the illumination of collimated light beams and quantitatively validate the performance of the proposed dimer. We also examine the stability of the dimer due to the lateral misalignments and we show how restoring forces bring the dimer into lateral equilibrium. The dimer can be employed in various practical applications such as optical manipulation, sensing and imaging.

  14. Thermodynamic properties for the sodium dimer

    NASA Astrophysics Data System (ADS)

    Song, Xiao-Qin; Wang, Chao-Wen; Jia, Chun-Sheng

    2017-04-01

    We present a closed-form expression of the classical vibrational partition function for the improved Rosen-Morse potential energy model. We give explicit expressions for the vibrational mean energy, vibrational specific heat, vibrational free energy, and vibrational entropy for diatomic molecule systems. The properties of these thermodynamic functions for the Na2 dimer are discussed in detail. We find that the improved Rosen-Morse potential model is superior to the harmonic oscillator in calculating the heat capacity for the Na2 molecules.

  15. Thermodynamics of acetylene van der Waals dimerization

    NASA Technical Reports Server (NTRS)

    Colussi, A. J.; Sander, S. P.; Friedl, R. R.

    1991-01-01

    Integrated band intensities of the 620/cm absorption in (C2H2)2 are measured by FTIR spectroscopy at constant acetylene pressure between 198 and 273 K. These data, in conjunction with ab initio results for (C2H2)2, are used for the statistical evaluation of the equilibrium constant Kp(T) for acetylene-cluster dimerization. The present results are used to clarify the role of molecular clusters in chemical systems at or near equilibrium, in particular in Titan's stratosphere.

  16. Equivalence between XY and dimerized models

    SciTech Connect

    Campos Venuti, Lorenzo; Roncaglia, Marco

    2010-06-15

    The spin-1/2 chain with XY anisotropic coupling in the plane and the XX isotropic dimerized chain are shown to be equivalent in the bulk. For finite systems, we prove that the equivalence is exact in given parity sectors, after taking care of the precise boundary conditions. The proof is given constructively by finding unitary transformations that map the models onto each other. Moreover, we considerably generalized our mapping and showed that even in the case of fully site-dependent couplings the XY chain can be mapped onto an XX model. This result has potential application in the study of disordered systems.

  17. Morphinane alkaloid dimers from Sinomenium acutum.

    PubMed

    Jin, Hui-Zi; Wang, Xiao-Ling; Wang, Hong-Bing; Wang, Yu-Bo; Lin, Li-Ping; Ding, Jian; Qin, Guo-Wei

    2008-01-01

    Two new morphinane alkaloid dimers, 2,2'-disinomenine (1) and 7',8'-dihydro-1,1'-disinomenine (2), and known 1, 1'-disinomenine (3), were isolated from ethanol extracts of stems of Sinomenium acutum. Their structures were elucidated on the basis of spectroscopic methods. The absolute configuration of alkaloids 1-3 was determined by direct comparison of their CD spectra with the known alkaloid sinomenine. The isolated alkaloids were tested for cytotoxicity against A549, P388, and HeLa cell lines, and 1 and 3 showed weak inhibition against A549 and Hela cells.

  18. Dimerization of thymol blue in solution: Theoretical evidence.

    PubMed

    Balderas-Hernández, Patricia; Vargas, Rubicelia; Rojas-Hernández, Alberto; Ramírez-Silva, Ma Teresa; Galván, Marcelo

    2007-02-28

    The possibility of dimerization of thymol blue was addressed by ab initio and force field calculations. In agreement with experimental information, a dimer forming symmetrical chemical environments for hydrogen bond formation was determined. This dimer is stable in vacuum and aqueous media and corresponds to the same protonated state proposed by the experiment. A comparison of the CVFF and MM3 force fields and ab initio results shows the suitability of CVFF to qualitatively describe this system.

  19. Chemical characteristics of dimer interfaces in the legume lectin family.

    PubMed

    Elgavish, S; Shaanan, B

    2001-04-01

    The Erythrina corallodendron lectin (EcorL) crystallizes in monoclinic and hexagonal crystal forms. Comparison of the newly determined hexagonal form (PDB code 1fyu) with the monoclinic form shows that the dimeric structure of EcorL reflects the inherent biological structure of the protein and is not an artifact of the crystal packing. To further understand the factors determining the dimerization modes of legume lectins, EcorL, concanavalin A (ConA), and Griffonia simplicifolia (GS4) were taken as representatives of the three unique dimers found in the family. Six virtual homodimers were generated. The hydropathy, amino acid composition, and solvation energy were calculated for all nine homodimers. Each of the three native dimers has a distinct chemical composition. EcorL has a dominant hydrophobic component, and ConA has a strong polar component, but in GS4 the three components contribute equally to the interface. This distribution pattern at the interface is unique to the native dimers and distinct from the partition observed in the virtual dimers. Amino acid composition of other members of the family that dimerize like EcorL or ConA maintain the same pattern of amino acids distribution observed in EcorL and ConA. However, lectins that dimerize like GS4 do not show a particularly distinct distribution. In all cases, the calculated solvation energy of the native dimer was lower than that of the virtual dimers, suggesting that the observed mode of dimerization is the most stable organization for the given sequence and tertiary structure. The dimerization type cannot be predicted by sequence analysis.

  20. Supersonic Molecular Jet Studies of the Pyrazine and Pyrimidine Dimers.

    DTIC Science & Technology

    1986-06-01

    the pyrazine and pyrimidine dimers. Computer simulations , based on a reasonable symmetric top algorithm, predict a resolution of at least 0.005 cm- I...Figure 9 Simulated rotational spectra of the pyrazine and pyrimidine origins. Figure 10 Two-color TOFMS rotational spectrum of the pyrazine dimer origin...top) and conDuter simulated rotational spectrum of the pyrazine dimer origin (bottom). The origin is at 30,849.5 cm- (-26.5 -1 -1 cm origin in figure

  1. Oligomerization of deoxynucleoside-bisphosphate dimers: template and linkage specificity

    NASA Technical Reports Server (NTRS)

    Visscher, J.; van der Woerd, R.; Bakker, C. G.; Schwartz, A. W.; Orgel, L. E. (Principal Investigator)

    1989-01-01

    Evidence is presented that a poly(U) template selectively favors the oligomerization of the activated, 3'-5' pyrophosphate-linked dimer pdAppdAp, in comparison with the 3'-3' and 5'-5' linked dimers. In the absence of poly(U), the 5'-5' linked dimer is the most reactive, and chains are formed which are more than 60 monomer units in length.

  2. VIDAS D-dimer: fast quantitative ELISA for measuring D-dimer in plasma.

    PubMed

    Pittet, J L; de Moerloose, P; Reber, G; Durand, C; Villard, C; Piga, N; Rolland, D; Comby, S; Dupuy, G

    1996-03-01

    VIDAS D-dimer (bioMérieux) is a new quantitative ELISA for D-dimer determination designed for the VIDAS automated system. The test contains single-dose, ready-to-use reagents and is completed within 35 min. Quantitative results are obtained from a calibration curve stored in the software of the system and expressed as fibrinogen equivalent units. The two-step capture/tag test relies on two complementary monoclonal anti-D-dimer antibodies, the second one being labeled with alkaline phosphatase. The upper limit of the measuring range is 1000 micrograms/L and the lower detection limit is <50 micrograms/L, which is below the lower limit of the reference interval (68-494 micrograms/L). Reproducibility (CV) within and between runs ranges from 5% to 7%. There is no interference from heparin, bilirubin, hemoglobin, fibrinogen degradation products, or plasma turbidity. Comparison with a conventional ELISA (y) gave good correlation (r= 0.91, n= 579) and comparable results (y= 1.35x - 148, S(y/x)= 750), especially for D-dimer concentrations ranging from 0 to 1000 micrograms/L (y= 1.09x - 10.6, r= 0.88, S(y/x)= 170).

  3. Rotational spectra of propargyl alcohol dimer: A dimer bound with three different types of hydrogen bonds

    SciTech Connect

    Mani, Devendra; Arunan, E.

    2014-10-28

    Pure rotational spectra of the propargyl alcohol dimer and its three deuterium isotopologues have been observed in the 4 to 13 GHz range using a pulsed-nozzle Fourier transform microwave spectrometer. For the parent dimer, a total of 51 transitions could be observed and fitted within experimental uncertainty. For two mono-substituted and one bi-substituted deuterium isotopologues, a total of 14, 17, and 19 transitions were observed, respectively. The observed rotational constants for the parent dimer [A = 2321.8335(4) MHz, B = 1150.4774(2) MHz, and C = 1124.8898(2) MHz] are close to those of the most stable structure predicted by ab initio calculations. Spectra of the three deuterated isotopologues and Kraitchman analysis positively confirm this structure. Geometrical parameters and “Atoms in Molecules” analysis on the observed structure reveal that the two propargyl alcohol units in the dimer are bound by three different types of hydrogen bonds: O–H⋯O, O–H⋯π, and C–H⋯π. To the best of our knowledge, propargyl alcohol seems to be the smallest molecule forming a homodimer with three different points of contact.

  4. Oligomerization of deoxynucleoside-biphosphate dimers - Template and linkage specificity

    NASA Technical Reports Server (NTRS)

    Visscher, J.; Van Der Woerd, R.; Bakker, C. G.; Schwartz, Alan W.

    1989-01-01

    The oligomerization of the activated 3-prime-5-prime pyrophosphate-linked dimer, pdAppdAp, is presently noted to be selectively favored by a poly(U) template over the 3-prime-3-prime and 5-prime-5-prime linked dimers. Both overall yields and the production of the longest oligomers were markedly stimulated by poly(U)'s presence; in its absence, the 5-prime-5-prime linked dimer became the most reactive, yielding chains of the order of 60 monomer-unit lengths. Remarkable self-organization properties are noted for the 5-prime-5-prime dimer of pdAp.

  5. Disordered clusters of Bak dimers rupture mitochondria during apoptosis

    PubMed Central

    Uren, Rachel T; O’Hely, Martin; Iyer, Sweta; Bartolo, Ray; Shi, Melissa X; Brouwer, Jason M; Alsop, Amber E; Dewson, Grant; Kluck, Ruth M

    2017-01-01

    During apoptosis, Bak and Bax undergo major conformational change and form symmetric dimers that coalesce to perforate the mitochondrial outer membrane via an unknown mechanism. We have employed cysteine labelling and linkage analysis to the full length of Bak in mitochondria. This comprehensive survey showed that in each Bak dimer the N-termini are fully solvent-exposed and mobile, the core is highly structured, and the C-termini are flexible but restrained by their contact with the membrane. Dimer-dimer interactions were more labile than the BH3:groove interaction within dimers, suggesting there is no extensive protein interface between dimers. In addition, linkage in the mobile Bak N-terminus (V61C) specifically quantified association between dimers, allowing mathematical simulations of dimer arrangement. Together, our data show that Bak dimers form disordered clusters to generate lipidic pores. These findings provide a molecular explanation for the observed structural heterogeneity of the apoptotic pore. DOI: http://dx.doi.org/10.7554/eLife.19944.001 PMID:28182867

  6. Bond operator method of dimerized ferrimagnetic spin chain

    NASA Astrophysics Data System (ADS)

    Chen, Yuge; Li, Yinxiang; Tian, Lijun; Chen, Bin

    2017-09-01

    We use bond operator method to study the dimerized ferrimagnetic spin chain. With the dimerization parameter g from 1 to 0, the model describes the system from normal ferrimagnetic state to dimer state. From the energy spectrums, the system energy is changed from ferrimagnetic spectrum to large energy gap at bond state. At finite temperature, the uniform susceptibility, internal energy and specific heat are calculated respectively with different dimerization parameters g. These results qualitatively agree with the numerical results of other methods quite well.

  7. Pathogenic Cysteine Removal Mutations in FGFR Extracellular Domains Stabilize Receptor Dimers and Perturb the TM Dimer Structure.

    PubMed

    Sarabipour, Sarvenaz; Hristova, Kalina

    2016-10-09

    Missense mutations that introduce or remove cysteine residues in receptor tyrosine kinases are believed to cause pathologies by stabilizing the active receptor tyrosine kinase dimers. However, the magnitude of this stabilizing effect has not been measured for full-length receptors. Here, we characterize the dimer stabilities of three full-length fibroblast growth factor receptor (FGFR) mutants harboring pathogenic cysteine substitutions: the C178S FGFR1 mutant, the C342R FGFR2 mutant, and the C228R FGFR3 mutant. We find that the three mutations stabilize the FGFR dimers. We further see that the mutations alter the configuration of the FGFR transmembrane dimers. Thus, both aberrant dimerization and perturbed dimer structure likely contribute to the pathological phenotypes arising due to these mutations.

  8. The Metabolic Fate of Deoxynivalenol and Its Acetylated Derivatives in a Wheat Suspension Culture: Identification and Detection of DON-15-O-Glucoside, 15-Acetyl-DON-3-O-Glucoside and 15-Acetyl-DON-3-Sulfate.

    PubMed

    Schmeitzl, Clemens; Warth, Benedikt; Fruhmann, Philipp; Michlmayr, Herbert; Malachová, Alexandra; Berthiller, Franz; Schuhmacher, Rainer; Krska, Rudolf; Adam, Gerhard

    2015-08-12

    Deoxynivalenol (DON) is a protein synthesis inhibitor produced by the Fusarium species, which frequently contaminates grains used for human or animal consumption. We treated a wheat suspension culture with DON or one of its acetylated derivatives, 3-acetyl-DON (3-ADON), 15-acetyl-DON (15-ADON) and 3,15-diacetyl-DON (3,15-diADON), and monitored the metabolization over a course of 96 h. Supernatant and cell extract samples were analyzed using a tailored LC-MS/MS method for the quantification of DON metabolites. We report the formation of tentatively identified DON-15-O-β-D-glucoside (D15G) and of 15-acetyl-DON-3-sulfate (15-ADON3S) as novel deoxynivalenol metabolites in wheat. Furthermore, we found that the recently identified 15-acetyl-DON-3-O-β-D-glucoside (15-ADON3G) is the major metabolite produced after 15-ADON challenge. 3-ADON treatment led to a higher intracellular content of toxic metabolites after six hours compared to all other treatments. 3-ADON was exclusively metabolized into DON before phase II reactions occurred. In contrast, we found that 15-ADON was directly converted into 15-ADON3G and 15-ADON3S in addition to metabolization into deoxynivalenol-3-O-β-D-glucoside (D3G). This study highlights significant differences in the metabolization of DON and its acetylated derivatives.

  9. Fibrillar dimer formation of islet amyloid polypeptides

    DOE PAGES

    Chiu, Chi -cheng; de Pablo, Juan J.

    2015-05-08

    Amyloid deposits of human islet amyloid polypeptide (hIAPP), a 37-residue hormone co-produced with insulin, have been implicated in the development of type 2 diabetes. Residues 20 – 29 of hIAPP have been proposed to constitute the amyloidogenic core for the aggregation process, yet the segment is mostly unstructured in the mature fibril, according to solid-state NMR data. Here we use molecular simulations combined with bias-exchange metadynamics to characterize the conformational free energies of hIAPP fibrillar dimer and its derivative, pramlintide. We show that residues 20 – 29 are involved in an intermediate that exhibits transient β-sheets, consistent with recent experimentalmore » and simulation results. By comparing the aggregation of hIAPP and pramlintide, we illustrate the effects of proline residues on inhibition of the dimerization of IAPP. The mechanistic insights presented here could be useful for development of therapeutic inhibitors of hIAPP amyloid formation.« less

  10. Dimeric uranyl complexes with bridging perrhenates.

    PubMed

    John, Gordon H; May, Iain; Sarsfield, Mark J; Collison, David; Helliwell, Madeleine

    2007-04-28

    The reaction between [UO2(ReO4)2.H(2)O] and two equivalents of either tri-n-butyl phosphine oxide (TBPO) or tri-iso-butyl phosphate (TiBP) results in the formation of [UO2(mu2-ReO4)(ReO4)(TBPO)2]2 (1) and [UO2(mu2-ReO4)(ReO4)(TiBP)2]2 (2) respectively. Both complexes crystallise as two structurally similar centrosymmetric dimers, the cores containing two uranyl moieties linked by bridging perrhenates. Two P=O donor ligands and one monodenatate perrhenate complete the pentagonal bipyramidal coordination sphere at each metal centre. Both complexes have also been characterised in the solid state by vibrational and absorption spectroscopy. Solution spectroscopic characterisation indicates that both perrhenate and phosphine oxide (1) or phosphate (2) remain coordinated, although it is not possible to state conclusively that the dimeric species remain intact. A low resolution structural study of a minor product from the reaction that yielded revealed a monomeric complex with only monodentate perrhenate coordination, [UO2(ReO4)2(H2O)(TiBP)2] (2'). These results represent the first structural evidence for the bridging coordination mode of perrhenate on coordination to an actinide and yields further insight into the possible solvent phase pertechnetate complexes that may exist in PUREX process phosphate rich solvent.

  11. The role of dimerization in prion replication.

    PubMed Central

    Tompa, Peter; Tusnády, Gábor E; Friedrich, Peter; Simon, István

    2002-01-01

    The central theme in prion diseases is the conformational transition of a cellular protein from a physiologic to a pathologic (so-called scrapie) state. Currently, two alternative models exist for the mechanism of this autocatalytic process; in the template assistance model the prion is assumed to be a monomer of the scrapie conformer, whereas in the nucleated polymerization model it is thought to be an amyloid rod. A recent variation on the latter assumes disulfide reshuffling as the mechanism of polymerization. The existence of stable dimers, let alone their mechanistic role, is not taken into account in either of these models. In this paper we review evidence supporting that the dimerization of either the normal or the scrapie state, or both, has a decisive role in prion replication. The contribution of redox changes, i.e., the temporary opening and possible rearrangement of the intramolecular disulfide bridge is also considered. We present a model including these features largely ignored so far and show that it adheres satisfactorily to the observed phenomenology of prion replication. PMID:11916832

  12. Dimers of nostocarboline with potent antibacterial activity.

    PubMed

    Locher, Hans H; Ritz, Daniel; Pfaff, Philippe; Gaertner, Mika; Knezevic, Andreja; Sabato, Daniela; Schroeder, Susanne; Barbaras, Damien; Gademann, Karl

    2010-01-01

    In this study, the in vitro antimicrobial activity and spectrum of new dimeric compounds derived from the cyanobacterial alkaloid nostocarboline were investigated. The mechanism of action and selectivity to bacteria were studied and compared to the cationic antiseptic chlorhexidine. Minimal inhibitory concentrations were determined against clinical isolates and against a panel of microbial reference strains using the CLSI microdilution method. Bacterial membrane damage was addressed by measuring ATP leakage and the mode of action was investigated in Escherichia coli reporter strains. Selectivity was tested by a cytotoxicity assay using MTS. The antimicrobial potency of dimers varied with length of the hydrophobic linker. The most potent compounds, NCD9 and NCD10, had a C10 and C12 linker, respectively, and showed strong activity against Gram-positive bacteria, notably methicillin-resistant Staphylococcus aureus strains. Similar to chlorhexidine, these compounds showed a rapid concentration-dependent bactericidal effect, which correlated with membrane damage as indicated by ATP leakage. NCD9, in contrast to NCD10 and chlorhexidine, lacked activity against yeast strains and showed low cytotoxicity in CHO cells indicating a high degree of selectivity. In E. coli reporter strains, NCD9 induced the DegP response pathway as well as the SOS response, suggesting interaction with both the cell envelope and DNA metabolism. The results presented in this report indicate the potential of this new class of cationic antimicrobial compounds for the design of potent and selective antibacterials with low cytotoxicity. Copyright © 2010 S. Karger AG, Basel.

  13. Rotational Spectrum of Propargyl Alcohol Dimer

    NASA Astrophysics Data System (ADS)

    Mani, Devendra; Arunan, E.

    2013-06-01

    Propargyl alcohol is a molecule of interest to astrophysics as well as combustion studies. Rotational-tunneling spectra of propargyl alcohol monomer is well known and shows that the molecule exists in gauche form. Recently we reported microwave spectra of Ar...propargyl alcohol complex. Propargyl alcochol exists in gauche form in the complex as well. In this study we have recorded pure rotational spectra of propargyl alcohol dimer between 4-13 GHz range.A total of 47 transitions, 24 a-type, 16 b-type and 7 c-type, have been observed and fitted with semi rigid rotor asymmetric top hamiltonian. The fitted rotational constants are: A = 2321.83323(47) MHz, B = 1150.47726(24) MHz and C = 1124.89000(20) MHz. The standard deviation for the fit is 2.5 kHz. The experimental rotational constants are very close to the structure predicted by ab-initio calculations in which two gauche-propargyl alcohol moieties are in three point contact stabilized by O-H...O, O-H...pi and C-H...pi interactions. Few transitions for duterated isotopologues of the dimer have also been observed and search for the remaining transitions is in progress. Details will be presented in the talk. E. Hirota,J. Mol. Spectrosc. 26 (1968) 335-350. J.C. Pearson, B.J. Drouin, J. Mol. Spectrosc. 234 (2005) 149-156. D. Mani, E. Arunan, ChemPhysChem 14 (2013) 754-763.

  14. Morphine glucuronidation and glucosidation represent complementary metabolic pathways that are both catalyzed by UDP-glucuronosyltransferase 2B7: kinetic, inhibition, and molecular modeling studies.

    PubMed

    Chau, Nuy; Elliot, David J; Lewis, Benjamin C; Burns, Kushari; Johnston, Martin R; Mackenzie, Peter I; Miners, John O

    2014-04-01

    Morphine 3-β-D-glucuronide (M3G) and morphine 6-β-D-glucuronide (M6G) are the major metabolites of morphine in humans. More recently, morphine-3-β-d-glucoside (M-3-glucoside) was identified in the urine of patients treated with morphine. Kinetic and inhibition studies using human liver microsomes (HLM) and recombinant UGTs as enzyme sources along with molecular modeling were used here to characterize the relationship between morphine glucuronidation and glucosidation. The M3G to M6G intrinsic clearance (C(Lint)) ratio (∼5.5) from HLM supplemented with UDP-glucuronic acid (UDP-GlcUA) alone was consistent with the relative formation of these metabolites in humans. The mean C(Lint) values observed for M-3-glucoside by incubations of HLM with UDP-glucose (UDP-Glc) as cofactor were approximately twice those for M6G formation. However, although the M3G-to-M6G C(Lint) ratio remained close to 5.5 when human liver microsomal kinetic studies were performed in the presence of a 1:1 mixture of cofactors, the mean C(Lint) value for M-3-glucoside formation was less than that of M6G. Studies with UGT enzyme-selective inhibitors and recombinant UGT enzymes, along with effects of BSA on morphine glycosidation kinetics, were consistent with a major role of UGT2B7 in both morphine glucuronidation and glucosidation. Molecular modeling identified key amino acids involved in the binding of UDP-GlcUA and UDP-Glc to UGT2B7. Mutagenesis of these residues abolished morphine glucuronidation and glucosidation. Overall, the data indicate that morphine glucuronidation and glucosidation occur as complementary metabolic pathways catalyzed by a common enzyme (UGT2B7). Glucuronidation is the dominant metabolic pathway because the binding affinity of UDP-GlcUA to UGT2B7 is higher than that of UDP-Glc.

  15. Mycosporine-glutamicol-glucoside: a natural UV-absorbing secondary metabolite of rock-inhabiting microcolonial fungi.

    PubMed

    Volkmann, Marc; Whitehead, Kenia; Rütters, Heike; Rullkötter, Jürgen; Gorbushina, Anna A

    2003-01-01

    Microcolonial ascomycetes are known to inhabit bare rock surfaces in cold and hot deserts and thus are habitually exposed to high levels of solar radiation. Several of these stress-tolerant fungal isolates, cultivated in the laboratory under daylight illumination, were studied for the presence of effective UV-radiation protection substances. Liquid chromatography/mass spectrometry (LC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS) analyses allowed for efficient separation and structure clarification of two mycosporines. It was demonstrated that both mycosporine-glutamicol-glucoside and mycosporine-glutaminol-glucoside are natural and constitutive secondary metabolites of microcolonial fungi. The function and relation of these substances in the fungal cell are discussed. Copyright 2003 John Wiley & Sons, Ltd.

  16. Iridoid glucosides from Nyctanthes arbortristis result in increased reactive oxygen species and cellular redox homeostasis imbalance in Leishmania parasite.

    PubMed

    Shukla, Anil Kumar; Patra, Sanjukta; Dubey, Vikash Kumar

    2012-08-01

    We report here the effect of iridoid glucosides, isolated from Nyctanthes arbortristis, on redox homeostasis of Leishmania parasite. These compounds led to an increase in reactive oxygen species by inhibiting a crucial enzyme of redox metabolism of the parasite. Our experiments clearly showed that these compounds are highly active as antileishmanial agents. The in vitro experiments on intra-macrophageal amastigotes showed significant killing of parasite even at very low concentration. Determination of mechanism of action of iridoid glucosides showed that increased ROS level leads to oxidative stress, cell membrane damage and apoptosis of Leishmania sp. Our cellular toxicity assays on Human embryonic kidney (HEK 293) and mouse macrophage (J774A.1) cell lines showed these compounds to be very safe for therapeutics application. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  17. PREPARATIVE SEPARATION OF AXIFOLIN-3-GLUCOSIDE, HYPEROSIDE AND AMYGDALIN FROM PLANT EXTRACTS BY HIGH-SPEED COUNTERCURRENT CHROMATOGRAPHY.

    PubMed

    Wei, Yun; Xie, Qianqian; Ito, Yoichiro

    2009-01-01

    High-speed countercurrent chromatography (HSCCC) was successfully used to isolate three bioactive compounds, i.e., amygdalin from bitter almond and taxifolin-3-glucoside and quercetin-3-galactoside (hyperoside) from water extract of Agrimonia pilosa Ledeb, respectively. From 1 g of the crude extract 65 mg of amygdalin was isolated at 97% purity using a two-phase solvent system composed of ethyl acetate-n-butanol-water (5:2:5, v/v) by preparative HSCCC. From a 400 mg amount of crude extract of Agrimonia pilosa Ledeb, 11 mg of taxifolin-3-glucoside and 8 mg of hyperoside were isolated at 96% purity using a two-phase solvent system composed of ethyl acetate-methanol-water (25:1:25, v/v) similarly by preparative HSCCC. The final structural identification was performed by MS, (1)H-NMR and (13)C-NMR Spectra.

  18. Periplanosides A-C: new insect-derived dihydroisocoumarin glucosides from Periplaneta americana stimulating collagen production in human dermal fibroblasts.

    PubMed

    Yang, Yong-Xun; Luo, Qi; Hou, Bo; Yan, Yong-Ming; Wang, Yue-Hu; Tang, Jian-Jun; Dong, Xiao-Ping; Ma, Xiu-Ying; Yang, Tong-Hua; Zuo, Zhi-Li; Cheng, Yong-Xian

    2015-01-01

    Three new dihydroisocoumarin glucosides, termed periplanosides A-C (1-3), a known analog, pericanaside (4), and the other twenty known compounds were isolated from the insect Periplaneta americana. Their structures including absolute configurations were determined by comprehensive spectroscopic analyses and computational methods. Biological evaluation showed that compound 2 could stimulate collagen production by 31.2% in human dermal fibroblasts-adult (HDFa) at the concentration of 30 μM, indicating its significance in skin repair and ulcer.

  19. A new sesquiterpene lactone glucoside with inhibitory effect on K562 cells from Ixeris sonchifolia (Bge) Hance.

    PubMed

    He, W-F; Xu, B-B; Pan, J-C; Lu, J-C; Song, S-J; Xu, S-X

    2006-09-01

    A new minor sesquiterpene lactone glucoside, ixerin ZA (1), together with 16 known compounds, were isolated from the whole plants of Ixeris sonchifolia (Bge) Hance. The structure of 1 was elucidated as 1(10),3,11(13)-guaiatriene-12,6-olide-2-one-3-O-[6'-(p-metheoxyphenylacetyl)]-beta-glucopyranoside on the basis of spectroscopic and chemical evidence. Compound 1 exhibited an inhibitory effect on K562 cells.

  20. Diversified glucosinolate metabolism: biosynthesis of hydrogen cyanide and of the hydroxynitrile glucoside alliarinoside in relation to sinigrin metabolism in Alliaria petiolata

    PubMed Central

    Frisch, Tina; Motawia, Mohammed S.; Olsen, Carl E.; Agerbirk, Niels; Møller, Birger L.; Bjarnholt, Nanna

    2015-01-01

    Alliaria petiolata (garlic mustard, Brassicaceae) contains the glucosinolate sinigrin as well as alliarinoside, a γ-hydroxynitrile glucoside structurally related to cyanogenic glucosides. Sinigrin may defend this plant against a broad range of enemies, while alliarinoside confers resistance to specialized (glucosinolate-adapted) herbivores. Hydroxynitrile glucosides and glucosinolates are two classes of specialized metabolites, which generally do not occur in the same plant species. Administration of [UL-14C]-methionine to excised leaves of A. petiolata showed that both alliarinoside and sinigrin were biosynthesized from methionine. The biosynthesis of alliarinoside was shown not to bifurcate from sinigrin biosynthesis at the oxime level in contrast to the general scheme for hydroxynitrile glucoside biosynthesis. Instead, the aglucon of alliarinoside was formed from metabolism of sinigrin in experiments with crude extracts, suggesting a possible biosynthetic pathway in intact cells. Hence, the alliarinoside pathway may represent a route to hydroxynitrile glucoside biosynthesis resulting from convergent evolution. Metabolite profiling by LC-MS showed no evidence of the presence of cyanogenic glucosides in A. petiolata. However, we detected hydrogen cyanide (HCN) release from sinigrin and added thiocyanate ion and benzyl thiocyanate in A. petiolata indicating an enzymatic pathway from glucosinolates via allyl thiocyanate and indole glucosinolate derived thiocyanate ion to HCN. Alliarinoside biosynthesis and HCN release from glucosinolate-derived metabolites expand the range of glucosinolate-related defenses and can be viewed as a third line of defense, with glucosinolates and thiocyanate forming protein being the first and second lines, respectively. PMID:26583022

  1. Species- and gender-dependent differences in the glucuronidation of a flavonoid glucoside and its aglycone determined using expressed UGT enzymes and microsomes.

    PubMed

    Dai, Peimin; Luo, Feifei; Wang, Ying; Jiang, Huangyu; Wang, Liping; Zhang, Guiyu; Zhu, Lijun; Hu, Ming; Wang, Xinchun; Lu, Linlin; Liu, Zhongqiu

    2015-12-01

    Flavonoids occur naturally as glucosides and aglycones. Their common phenolic hydroxyl groups may trigger extensive UDP-glucuronosyltransferase (UGT)- catalysed metabolism. Unlike aglycones, glucosides contain glucose moieties. However, the influence of these glucose moieties on glucuronidation of glucosides and aglycones remains unclear. In this study, the flavonoid glucoside tilianin and its aglycone acacetin were used as model compounds. The glucuronidation characteristics and enzyme kinetics of tilianin and acacetin were compared using human UGT isoforms, liver microsomes and intestinal microsomes obtained from different animal species. Tilianin and acacetin were metabolized into different glucuronides, with UGT1A8 produced as the main isoform. Assessment of enzyme kinetics in UGT1A8, human liver microsomes and human intestinal microsomes revealed that compared with tilianin, acacetin displayed lower Km (0.6-, 0.7- and 0.6-fold, respectively), higher Vmax (20-, 60- and 230-fold, respectively) and higher clearance (30-, 80- and 300-fold, respectively). Furthermore, glucuronidation of acacetin and tilianin showed significant species- and gender-dependent differences. In conclusion, glucuronidation of flavonoid aglycones is faster than that of glucosides in the intestine and the liver. Understanding the metabolism and species- and gender-dependent differences between glucosides and aglycones is crucial for the development of drugs from flavonoids.

  2. MATE Transporters Facilitate Vacuolar Uptake of Epicatechin 3′-O-Glucoside for Proanthocyanidin Biosynthesis in Medicago truncatula and Arabidopsis[C][W

    PubMed Central

    Zhao, Jian; Dixon, Richard A.

    2009-01-01

    Expression of the Arabidopsis thaliana MYB transcription factor TRANSPARENT TESTA 2 (TT2) in Medicago trunculata hairy roots induces both proanthocyanidin accumulation and the ATP-dependent vacuolar/vesicular uptake of epicatechin 3′-O-glucoside; neither process is active in control roots that do, however, possess anthocyanidin 3-O-glucoside vacuolar uptake activity. A vacuolar membrane-localized multidrug and toxic compound extrusion (MATE) transporter, Medicago MATE1, was identified at the molecular level and shown to preferentially transport epicatechin 3′-O-glucoside. Genetic evidence has implicated TT12, a tonoplastic MATE transporter from Arabidopsis, in the transport of precursors for proanthocyanidin biosynthesis in the seed coat. However, although Arabidopsis TT12 facilitates the transport of cyanidin 3-O-glucoside into membrane vesicles when expressed in yeast, there is no evidence that cyanidin 3-O-glucoside is converted to proanthocyanidins after transport into the vacuole. Here, we show that Arabidopsis TT12, like Medicago MATE1, functions to transport epicatechin 3′-O-glucoside as a precursor for proanthocyanidin biosynthesis, and Medicago MATE1 complements the seed proanthocyanidin phenotype of the Arabidopsis tt12 mutant both quantitatively and qualitatively. On the basis of biochemical properties, tissue-specific expression pattern, and genetic loss-of-function analysis, we conclude that MATE1 is an essential membrane transporter for proanthocyanidin biosynthesis in the Medicago seed coat. Implications of these findings for the assembly of oligomeric proanthocyanidins are discussed. PMID:19684242

  3. Structural probing of a pathogenic tRNA dimer

    PubMed Central

    ROY, MARC D.; WITTENHAGEN, LISA M.; KELLEY, SHANA O.

    2005-01-01

    The A3243G mutation within the human mitochondrial (hs mt) tRNALeu(UUR) gene is associated with maternally inherited deafness and diabetes (MIDD) and other mitochondrial encephalopathies. One of the most pronounced structural effects of this mutation is the disruption of the native structure through stabilization of a high-affinity dimeric complex. We conducted a series of studies that address the structural properties of this tRNA dimer, and we assessed its formation under physiological conditions. Enzymatic probing was used to directly define the dimeric interface for the complex, and a discrete region of the D-stem and loop of hs mt tRNALeu(UUR) was identified. The dependence of dimerization on magnesium ions and temperature was also tested. The formation of the tRNA dimer is influenced by temperature, with dimerization becoming more efficient at physiological temperature. Complexation of the mutant tRNA is also affected by the amount of magnesium present, and occurs at concentrations present intracellularly. Terbium probing experiments revealed a specific metal ion-binding site localized at the site of the A3243G mutation that is unique to the dimer structure. This metal ion-binding site presents a striking parallel to dimeric complexes of viral RNAs, which use the same hexanucleotide sequence for complexation and feature a similarly positioned metal ion-binding site within the dimeric structure. Taken together, these results indicate that the unique dimeric complex formed by the hs mt tRNALeu(UUR) A3243G mutant exhibits interesting similarities to biological RNA dimers, and may play a role in the loss of function caused by this mutation in vivo. PMID:15701731

  4. [Influence of metal ions on stability of 2,3,5,4'-tetrahydroxy stilbene-2-O-β-D-glucoside contained in Polygoni Multiflori Radix].

    PubMed

    Li, Rui-yu; Feng, Wu-wen; Li, Xiao-fei; Zhang, Ding-kun; Li, Chun-yu; Meng, Ya-kun; Bai, Zhao-fang; Song, Hai-bo; Du, Xiao-xi; Xia, Hou-lin; Wang, Jia-bo; Xiao, Xiao-he

    2016-01-01

    Decoction is one of the most commonly used dosage forms of traditional Chinese medicine. The stability of chemical constituents in decoction is closely related to the clinical efficacy and safety. There were few reports about the influence of metal ions in the stability of chemical constituents in traditional Chinese medicine. However, there is no evidence that metal ions in decoction water need to be controlled. In this study, 2,3,5,4'-tetrahydroxy stilbene-2-O-β-D-glucoside (THSG), one of the main constituents in Polygoni Multiflori Radix was studied. Ordinary tap water, deionized water, and water containing different metal ions were used to investigate and compare the influence on THSG. The results showed that after storage in a dark place at the room temperature for 10 days, the degradation of THSG was 7% in deionized water, while undetectable in tap water. The content of THSG could be decreased by different kinds of metal ions, and the effect was concentration-dependent. Moreover, Fe3+ and Fe2+ showed the greatest influence at the same concentration; and our study has shown that THSG decreased more than 98% in Fe and Fe2+ solutions at 500 ppm concentration. In the same time we found out p-hydroxybenzaldehyde (molecular weight: 122.036 7) and 2,3,5-trihydroxybenzaldehyde-2-O-glycoside (molecular weight: 316.079 4) were the main degradation products of THSG in tap water and water containing Cu2+, Ca2+, Zn2+, Mg2+ and Al3+. The product of THSG dimer with a water molecule was found in water containing Fe3+ and Fe2+. The above results showed that the metal ions in water could significantly influence the stability of THSG in water, indicating that the clinical efficacy and safety of decoction would be affected if the metal ions in water were not under control. It's suggested that deionized water should be used in the preparation of decoction containing Polygoni Multiflori Radix in the clinic to avoid degradation of THSG. Meanwhile, decoction prepared by tap water

  5. Cool-cultivated red leaf lettuce accumulates cyanidin-3-O-(6″-O-malonyl)-glucoside and caffeoylmalic acid.

    PubMed

    Becker, Christine; Klaering, Hans-Peter; Kroh, Lothar W; Krumbein, Angelika

    2014-03-01

    Cultivating lettuce in greenhouses at low temperatures improves its CO2-balance and may increase its content of flavonoid glycosides and phenolic acids. We cultivated 5weeks old red leaf lettuce seedlings at 20/15°C (day/night) or 12/7°C until plants reached comparable growth stages: small heads were harvested after 13 (warm) and 26 (cool)days, while mature heads were harvested after 26 (warm) or 52 (cool)days. Additionally, some plants were cultivated first cool then warm and vice versa (39days). Cool-cultivated small heads had higher concentrations of cyanidin-3-O-(6″-O-malonyl)-glucoside and caffeoylmalic acid than warm-cultivated ones but we detected no differences concerning quercetin and luteolin glycosides or di-O-caffeoyltartaric and 5-O-caffeoylquinic acid. Regarding mature heads, there were only differences concerning cyanidin-3-O-(6″-O-malonyl)-glucoside. We therefore suggest that only cyanidin-3-O-(6″-O-malonyl)-glucoside was truly responsive to temperatures alone. Previously reported contrasting effects may rather be due to comparison of different growth stages or interactive effects with radiation. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

  6. Isolation of antioxidative phenolic glucosides from lemon juice and their suppressive effect on the expression of blood adhesion molecules.

    PubMed

    Miyake, Yoshiaki; Mochizuki, Mika; Okada, Miki; Hiramitsu, Masanori; Morimitsu, Yasujiro; Osawa, Toshihiko

    2007-08-01

    Phenolic glucosides having radical scavenging activity were examined from the fraction eluted with 20% methanol on Amberlite XAD-2 resin applied to lemon (Citrus limon) juice by using reversed phase chromatography. Four phenolic glucosides were identified as 1-feruloyl-beta-D-glucopyranoside, 1-sinapoyl-beta-D-glucopyranoside, 6,8-di-C-glucosylapigenin and 6,8-di-C-glucosyldiosmetin by (1)H-NMR, (13)C-NMR, and MS analyses. They exhibited radical scavenging activity for 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide, although the activity was low in comparison with eriocitrin, a potent antioxidant in lemon fruit, and the eriodictyol of its aglycone. The phenolic compounds in lemon juice were examined for their suppressive effect on the expression of blood adhesion molecules by measuring the expression of intercellular adhesion molecule-1 (ICAM-1) in human umbilical vein endothelial cells (HUVECs) induced by necrosis factor-alpha (TNF-alpha). 6,8-Di-C-glucosylapigenin, apigenin, and diosmentin of the flavones were found to significantly suppress the expression of ICAM-1 at 10 muM (P<0.05). The phenolic glucosides isolated in this study were contained in comparative abundance in daidai (Citrus aurantium) and niihime (Citrus unshiu x Citrus tachibana) among the sour citrus juices.

  7. Anti-inflammatory activity of Korean thistle Cirsium maackii and its major flavonoid, luteolin 5-O-glucoside.

    PubMed

    Jung, Hyun Ah; Jin, Seong Eun; Min, Byung-Sun; Kim, Byung-Woo; Choi, Jae Sue

    2012-06-01

    The anti-inflammatory activity of whole Cirsium maackii (family Compositae) plants and of its major flavonoid, luteolin 5-O-glucoside, was evaluated for their ability to inhibit lipopolysaccharide (LPS)-induced nitric oxide (NO) production, inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) protein expression, and tert-butylhydroperoxide (t-BHP)-induced reactive oxygen species (ROS) generation in RAW 264.7 murine macrophage cells. The methanolic extract of C. maackii showed strong anti-inflammatory activity, and was thus fractionated with several solvents. The ethyl acetate-soluble fraction, exhibiting the highest anti-inflammatory activity potential, was further to yield a major flavonoid, luteolin 5-O-glucoside. We found that luteolin 5-O-glucoside, at a non-toxic concentration, inhibited LPS-induced NO production and t-BHP-induced ROS generation in a dose-dependent manner in RAW 264.7 cells. It also suppressed the expression of iNOS and COX-2 in LPS-stimulated macrophages. Furthermore, the efficacies of the methanolic extract of C. maackii in inhibiting both NO and ROS were attributed to its flavonoid content by HPLC analysis. These results indicated that C. maackii whole plants and its flavonoids inhibit the expression of iNOS and COX-2 in through the inhibition of ROS generation, and therefore can be considered as a useful therapeutic and preventive approach for the treatment of various inflammatory and oxidative stress-related diseases.

  8. Salt bridge residues between I-Ak dimer of dimers alpha-chains modulate antigen presentation.

    PubMed

    Yadati, S; Nydam, T; Demian, D; Wade, T K; Gabriel, J L; Barisas, B G; Wade, W F

    1999-03-15

    Class II dimers of dimers are predicted to have functional significance in antigen presentation. The putative contact amino acids of the I-Ak class II dimer of dimers have been identified by molecular modeling based on the DR1 crystal structure (Nydam et al., Int. Immunol. 10, 1237,1998). We have previously reported the role in antigen presentation of dimer of dimers contact amino acids located in the C-terminal domains of the alpha- and beta-chains of class II. Our calculations show that residues Ealpha89 and Ralpha145 in the alpha2-domain form an inter alpha-chain salt bridge between pairs of alphabeta-heterodimers. Other residues, Qalpha92 and Nalpha115, may be involved in close association in that part of the alpha-chain. We investigated the role of these amino acids on class II expression and antigen presentation. Class II composed of an Ealpha89K substituted alpha-chain paired with a wt beta-chain exhibited inhibited antigen presentation and expression of alpha-chain serologic epitopes. In contrast, mutation of Ralpha145E had less affect on antigen presentation and did not affect I-Ak serologic epitopes. Interchanging charges of the salt bridge residues by expressing both Ralpha145E and Ealpha89K on the same chain obviated the large negative effect of the Ealpha89K mutation on antigen presentation but not on the serologic epitopes. Our results are similar for those reported for mutation of DR3's inter-chain salt bridge with the exception that double mutants did not moderate the DR3 defect. Interestingly, the amino acids differences between I-A and DR change the location of the inter-chain salt bridges. In DR1 these residues are located at positions Ealpha88 and Kalpha111; in I-Ak these residues are located at position Ealpha89 and Ralpha145. Inter alpha-chain salt bridges are thus maintained in various class II molecules by amino acids located in different parts of the alpha2-domain. This conservation of structure suggests that considerable functional

  9. Spectral alteration and degradation of cyanidin-3-glucoside exposed to pulsed electric field.

    PubMed

    Zhang, Yan; Sun, Jianxia; Hu, Xiaosong; Liao, Xiaojun

    2010-03-24

    Anthocyanins are polyphenol antioxidants that have been shown to prevent many chronic diseases. The compounds are not stable, so they tend to be decolorized or degraded during processing and storage. In this study, the spectral characteristics alteration and degradation products of cyanidin-3-glucoside (Cyd-3-glc) exposed to pulsed electric field (PEF) were investigated, and the reaction kinetics was discussed. The intensity of the UV-vis spectra decreased noticeably upon PEF treatment without modification of the spectral pattern. Protocatechuic acid and 2,4,6-trihydroxybenzoic acid were identified as degradation products of both PEF and thermally treated Cyd-3-glc, but cyanidin present in thermally treated Cyd-3-glc was absent in PEF-treated Cyd-3-glc, indicating that the first step of Cyd-3-glc degradation induced by PEF was not the hydrolysis of glycosidic bonds, which was different from that of thermal degradation. With increased electric field intensity or treatment time, the degradation of Cyd-3-glc and the formation of protocatechuic acid were enhanced; their kinetics (except 7 kV/cm for protocatechuic acid formation) were well fitted to a first-order reaction. Meanwhile, a good correlation was present between Cyd-3-glc degradation and protocatechuic acid formation.

  10. Occurrence of deoxynivalenol and its major conjugate, deoxynivalenol-3-glucoside, in beer and some brewing intermediates.

    PubMed

    Kostelanska, Marta; Hajslova, Jana; Zachariasova, Milena; Malachova, Alexandra; Kalachova, Kamila; Poustka, Jan; Fiala, Jaromir; Scott, Peter M; Berthiller, Franz; Krska, Rudolf

    2009-04-22

    Since deoxynivalenol (DON), the main representative of Fusarium toxic secondary metabolites, is a relatively common natural contaminant in barley, its traces can be detected in many commercial beers. Our previous study reporting for the first time the occurrence of relatively high levels of DON-3-glucoside (DON-3-Glc) in malt and beer prepared from relatively "clean" barley (semiscale experimental conditions) induced a follow-up investigation focused on this DON conjugate in commercial beers. The current survey involving in total 176 beers, representing different brands, and collected at various markets, has documented a ubiquitous occurrence of DON-3-Glc in this product. Its levels even exceeded that of free DON in some samples; the highest level found was 37 microg/L. In addition to glucosylated DON, its acetylated forms (ADONs) were also common contaminants in most of the beers. Generally, stronger beers (higher alcohol content) tended to contain higher levels of DON and its conjugates. No distinct relationship between the contamination of malt and beer was observed in samples collected from several breweries. Attention was also paid to comparison of data on malts obtained by LC-MS/MS and ELISA DON-dedicated kits. The latter provided apparently higher levels of DON, the most distinct difference being observed for malts processed at higher temperatures (caramel and roasted malts). The nature of this phenomenon has not yet been explained; in addition to cross-reacting species, other factors, such as the higher content of dark pigment, can also be the cause.

  11. Prophylactic Efficacy of Quercetin 3-β-O-d-Glucoside against Ebola Virus Infection.

    PubMed

    Qiu, Xiangguo; Kroeker, Andrea; He, Shihua; Kozak, Robert; Audet, Jonathan; Mbikay, Majambu; Chrétien, Michel

    2016-09-01

    Ebola outbreaks occur on a frequent basis, with the 2014-2015 outbreak in West Africa being the largest one ever recorded. This outbreak has resulted in over 11,000 deaths in four African countries and has received international attention and intervention. Although there are currently no approved therapies or vaccines, many promising candidates are undergoing clinical trials, and several have had success in promoting recovery from Ebola. However, these prophylactics and therapeutics have been designed and tested only against the same species of Ebola virus as the one causing the current outbreak. Future outbreaks involving other species would require reformulation and possibly redevelopment. Therefore, a broad-spectrum alternative is highly desirable. We have found that a flavonoid derivative called quercetin 3-β-O-d-glucoside (Q3G) has the ability to protect mice from Ebola even when given as little as 30 min prior to infection. Furthermore, we have demonstrated that this compound targets the early steps of viral entry. Most promisingly, antiviral activity against two distinct species of Ebola virus was seen. This study serves as a proof of principle that Q3G has potential as a prophylactic against Ebola virus infection. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  12. The Multiple Strategies of an Insect Herbivore to Overcome Plant Cyanogenic Glucoside Defence

    PubMed Central

    Pentzold, Stefan; Zagrobelny, Mika; Roelsgaard, Pernille Sølvhøj; Møller, Birger Lindberg; Bak, Søren

    2014-01-01

    Cyanogenic glucosides (CNglcs) are widespread plant defence compounds that release toxic hydrogen cyanide by plant β-glucosidase activity after tissue damage. Specialised insect herbivores have evolved counter strategies and some sequester CNglcs, but the underlying mechanisms to keep CNglcs intact during feeding and digestion are unknown. We show that CNglc-sequestering Zygaena filipendulae larvae combine behavioural, morphological, physiological and biochemical strategies at different time points during feeding and digestion to avoid toxic hydrolysis of the CNglcs present in their Lotus food plant, i.e. cyanogenesis. We found that a high feeding rate limits the time for plant β-glucosidases to hydrolyse CNglcs. Larvae performed leaf-snipping, a minimal disruptive feeding mode that prevents mixing of plant β-glucosidases and CNglcs. Saliva extracts did not inhibit plant cyanogenesis. However, a highly alkaline midgut lumen inhibited the activity of ingested plant β-glucosidases significantly. Moreover, insect β-glucosidases from the saliva and gut tissue did not hydrolyse the CNglcs present in Lotus. The strategies disclosed may also be used by other insect species to overcome CNglc-based plant defence and to sequester these compounds intact. PMID:24625698

  13. Enzymatic hydrolysis of steryl glucosides, major contaminants of vegetable oil-derived biodiesel.

    PubMed

    Aguirre, Andres; Peiru, Salvador; Eberhardt, Florencia; Vetcher, Leandro; Cabrera, Rodolfo; Menzella, Hugo G

    2014-05-01

    Biodiesels are mostly produced from lipid transesterification of vegetable oils, including those from soybean, jatropha, palm, rapeseed, sunflower, and others. Unfortunately, transesterification of oil produces various unwanted side products, including steryl glucosides (SG), which precipitate and need to be removed to avoid clogging of filters and engine failures. So far, efficient and cost-effective methods to remove SGs from biodiesel are not available. Here we describe for the first time the identification, characterization and heterologous production of an enzyme capable of hydrolyzing SGs. A synthetic codon-optimized version of the lacS gene from Sulfolobus solfataricus was efficiently expressed and purified from Escherichia coli, and used to treat soybean derived biodiesel containing 100 ppm of SGs. After optimizing different variables, we found that at pH 5.5 and 87 °C, and in the presence of 0.9 % of the emulsifier polyglycerol polyricinoleate, 81 % of the total amount of SGs present in biodiesel were hydrolyzed by the enzyme. This remarkable reduction in SGs suggests a path for the removal of these contaminants from biodiesel on industrial scale using an environmentally friendly enzymatic process.

  14. Effect of heat/pressure on cyanidin-3-glucoside ethanol model solutions

    NASA Astrophysics Data System (ADS)

    Corrales, M.; Lindauer, R.; Butz, P.; Tauscher, B.

    2008-07-01

    The stability of cyanidin-3-glucoside (Cy3gl) in 50% ethanol model solutions under heat/pressure treatments was investigated. Cy3gl was rapidly degraded when solutions were subjected to a heat/pressure treatment. The higher the pressure and the temperature used, the higher the degradation. Moreover, the degradation was increased according to increasing holding times. Parallel to the degradation of Cy3gl several hydrolytic products were formed and identified by LC-DAD/ESI-MS. The degradation of Cy3gl was well fitted to a first order reaction (R=0.99). This study pointed out the rate of susceptibility of Cy3gl in model solutions to degrade when exposed to a heat/pressure treatment and the trigger effect of high hydrostatic pressure to hydrolyse Cy3gl. By contrast, the degradation of anthocyanins in a food matrix (red grape extract solutions) was negligible after a heat/pressure process at 600MPa, 70°C during 1h (P >0.05).

  15. Hemisynthesis and structural and chromatic characterization of delphinidin 3-O-glucoside-vescalagin hybrid pigments.

    PubMed

    García-Estévez, Ignacio; Jacquet, Rémi; Alcalde-Eon, Cristina; Rivas-Gonzalo, Julián C; Escribano-Bailón, M Teresa; Quideau, Stéphane

    2013-11-27

    During red wine maturation in the presence of oak wood, reactions involving anthocyanins and ellagitannins might affect wine organoleptic properties such as color and astringency. In this work, the condensation reaction between myrtillin (delphinidin 3-O-glucoside) and vescalagin has been performed to determine the behavior of this anthocyanin in this kind of reaction and to assess the possible impact of such a reaction in wine color modulation. Two different hybrid pigments have been hemisynthetized and characterized by HPLC-DAD-MS and NMR spectroscopy. These pigments have been identified as 1-deoxyvescalagin-(1β→8)-myrtillin (major) and 1-deoxyvescalagin-(1β→6)-myrtillin (minor). The minor pigment could be formed both by the condensation reaction and by a regioisomerization process from the major pigment. Moreover, the chromatic properties of these pigments have been studied and compared to those of myrtillin. The hybrid pigments showed an important bathochromic shift (ca. 20 nm) in the maximum absorbance wavelength and lower molar absorption coefficients.

  16. Effects of iriflophenone 3-C-β-glucoside on fasting blood glucose level and glucose uptake

    PubMed Central

    Pranakhon, Ratree; Aromdee, Chantana; Pannangpetch, Patchareewan

    2015-01-01

    Background: One of the biological activities of agar wood (Aquilaria sinensis Lour., Thymelaeaceae), is anti-hyperglycemic activity. The methanolic extract (ME) was proven to possess the fasting blood glucose activity in rat and glucose uptake transportation by rat adipocytes. Objective: To determine the decreasing fasting blood glucose level of constituents affordable for in vivo test. If the test was positive, the mechanism which is positive to the ME, glucose transportation, will be performed. Materials and Methods: The ME was separated by column chromatography and identified by spectroscopic methods. Mice was used as an animal model (in vivo), and rat adipocytes were used for the glucose transportation activity (in vitro). Result: Iriflophenone 3-C-β-glucoside (IPG) was the main constituent, 3.17%, and tested for the activities. Insulin and the ME were used as positive controls. The ME, IPG and insulin lowered blood glucose levels by 40.3, 46.4 and 41.5%, respectively, and enhanced glucose uptake by 152, 153, and 183%, respectively. Conclusion: These findings suggest that IPG is active in lowering fasting blood glucose with potency comparable to that of insulin. PMID:25709215

  17. Phenylpropenoic Acid Glucoside from Rooibos Protects Pancreatic Beta Cells against Cell Death Induced by Acute Injury

    PubMed Central

    Himpe, Eddy; Cunha, Daniel A.; Song, Imane; Bugliani, Marco; Marchetti, Piero; Cnop, Miriam; Bouwens, Luc

    2016-01-01

    Objective Previous studies demonstrated that a phenylpropenoic acid glucoside (PPAG) from rooibos (Aspalathus linearis) extract had anti-hyperglycemic activity and significant protective effects on the pancreatic beta cell mass in a chronic diet-induced diabetes model. The present study evaluated the cytoprotective effect of the phytochemical on beta cells exposed to acute cell stress. Methods Synthetically prepared PPAG was administered orally in mice treated with a single dose of streptozotocin to acutely induce beta cell death and hyperglycemia. Its effect was assessed on beta cell mass, proliferation and apoptotic cell death. Its cytoprotective effect was also studied in vitro on INS-1E beta cells and on human pancreatic islet cells. Results Treatment with the phytochemical PPAG protected beta cells during the first days after the insult against apoptotic cell death, as evidenced by TUNEL staining, and prevented loss of expression of anti-apoptotic protein BCL2 in vivo. In vitro, PPAG protected INS-1E beta cells from streptozotocin-induced apoptosis and necrosis in a BCL2-dependent and independent way, respectively, depending on glucose concentration. PPAG also protected human pancreatic islet cells against the cytotoxic action of the fatty acid palmitate. Conclusions These findings show the potential use of PPAG as phytomedicine which protects the beta cell mass exposed to acute diabetogenic stress. PMID:27299564

  18. PLS-Prediction and Confirmation of Hydrojuglone Glucoside as the Antitrypanosomal Constituent of Juglans Spp.

    PubMed

    Ellendorff, Therese; Brun, Reto; Kaiser, Marcel; Sendker, Jandirk; Schmidt, Thomas J

    2015-05-29

    Naphthoquinones (NQs) occur naturally in a large variety of plants. Several NQs are highly active against protozoans, amongst them the causative pathogens of neglected tropical diseases such as human African trypanosomiasis (sleeping sickness), Chagas disease and leishmaniasis. Prominent NQ-producing plants can be found among Juglans spp. (Juglandaceae) with juglone derivatives as known constituents. In this study, 36 highly variable extracts were prepared from different plant parts of J. regia, J. cinerea and J. nigra. For all extracts, antiprotozoal activity was determined against the protozoans Trypanosoma cruzi, T. brucei rhodesiense and Leishmania donovani. In addition, an LC-MS fingerprint was recorded for each extract. With each extract's fingerprint and the data on in vitro growth inhibitory activity against T. brucei rhodesiense a Partial Least Squares (PLS) regression model was calculated in order to obtain an indication of compounds responsible for the differences in bioactivity between the 36 extracts. By means of PLS, hydrojuglone glucoside was predicted as an active compound against T. brucei and consequently isolated and tested in vitro. In fact, the pure compound showed activity against T. brucei at a significantly lower cytotoxicity towards mammalian cells than established antiprotozoal NQs such as lapachol.

  19. Preparation and characterization, using high-performance liquid chromatography, of an enzyme forming glucosides of cytokinins.

    PubMed

    Entsch, B; Parker, C W; Letham, D S; Summons, R E

    1979-09-12

    Cytokinins can occur naturally as glycosides with beta-D-glucose as the sugar substituent. From radish (Raphanus sativus) cotyledons, an enzyme has been partly purified which synthesizes the 7-glucopyranoside of zeatin [6-(4-hydroxy-3-methylbut-trans-2-enylamino)purine], a compound known to occur in this species. High-performance reverse-phase liquid chromatography was uniquely useful as the analytical procedure for quantitative study of the minute amounts of enzyme available. The enzyme uses UDPglucose as the source of the sugar residue. A large number of derivatives of purine are glucosylated, but adenine derivatives with an alkyl side chain at least three carbon atoms in length at position N6 are preferentially glucosylated. This corresponds to the structural features required for high cytokinin activity. The 7-glucoside of zeatin is known to be very weakly active in cytokinin bioassays. Hence, this enzyme, and others catalyzing the same reaction, have a role in the regulation of cytokinin activity.

  20. Subcellular Localization of the Cyanogenic Glucoside of Sorghum by Autoradiography 1

    PubMed Central

    Saunders, James A.; Conn, Eric E.; Lin, Chin Ho; Stocking, C. Ralph

    1977-01-01

    The use of microautoradiography at the electron microscopic level indicates that the vacuole is the site of accumulation of the cyanogenic glucoside of Sorghum bicolor. When a specific biosynthetic precursor of dhurrin, p-hydroxy[3,5-3H]phenylacetaldoxime, was used, 90% of the tritium label was recovered in the vacuoles of tissue prepared for microautoradiography. l-[3,5-3H]Tyrosine and d-[1-3H(N)]glucose, nonspecific precursors of dhurrin, of differing solubilities and biosynthetic capacity, were also fed to the shoots. The data obtained from these controls indicated that the high recovery of label in the vacuole of aldoxime-fed shoots was not indicative simply of the size of the vacuole, nor was it a result of movement of labeled compounds during preparation of the tissue for electron microscopy. The problem of movement of these labeled compounds during dehydration of tissue was dramatically reduced by chemical dehydration in 2,2-dimethoxypropane in less than 30 minutes rather than with routine dehydration in acetone or alcohol series for 24 hours. Images PMID:16659911

  1. Souring and breakdown of cyanogenic glucosides during the processing of cassava into akyeke.

    PubMed

    Obilie, Eric Mantey; Tano-Debrah, Kwaku; Amoa-Awua, Wisdom Kofi

    2004-05-15

    The population and composition of the lactic acid bacteria microbiota as well as the content of cyanogenic glucosides occurring at various stages of fermentation and subsequent processing of cassava roots into akyeke, a steamed sour cassava meal, were investigated. The number of lactic acid bacteria and percentage titratable acidity increased during 5 days of fermentation, but decreases were observed in the subsequent operations of 'washing' the dough with water followed by partial drying and steaming. In field and laboratory samples, Lactobacillus plantarum accounted for 59.3% and 52.3%, Lactobacillus brevis 23.3% and 22.8% and Leuconostoc mesenteroides subsp. cremoris 14.5% and 15.8%, respectively, of all lactic acid bacteria isolated at various stages of fermentation and processing. A reduction of about 98% occurred in the total cyanogens (CN) content of cassava roots during processing, from 69.3 to 1.4 and 110.3 to 2.8 mg CN equivalent/kg dry weight for laboratory and field samples of akyeke, respectively.

  2. Prophylactic Efficacy of Quercetin 3-β-O-d-Glucoside against Ebola Virus Infection

    PubMed Central

    Kroeker, Andrea; He, Shihua; Kozak, Robert; Audet, Jonathan; Mbikay, Majambu

    2016-01-01

    Ebola outbreaks occur on a frequent basis, with the 2014-2015 outbreak in West Africa being the largest one ever recorded. This outbreak has resulted in over 11,000 deaths in four African countries and has received international attention and intervention. Although there are currently no approved therapies or vaccines, many promising candidates are undergoing clinical trials, and several have had success in promoting recovery from Ebola. However, these prophylactics and therapeutics have been designed and tested only against the same species of Ebola virus as the one causing the current outbreak. Future outbreaks involving other species would require reformulation and possibly redevelopment. Therefore, a broad-spectrum alternative is highly desirable. We have found that a flavonoid derivative called quercetin 3-β-O-d-glucoside (Q3G) has the ability to protect mice from Ebola even when given as little as 30 min prior to infection. Furthermore, we have demonstrated that this compound targets the early steps of viral entry. Most promisingly, antiviral activity against two distinct species of Ebola virus was seen. This study serves as a proof of principle that Q3G has potential as a prophylactic against Ebola virus infection. PMID:27297486

  3. Isorhamnetin-3-glucoside alleviates oxidative stress and opacification in selenite cataract in vitro.

    PubMed

    Devi, V Gayathri; Rooban, B N; Sasikala, V; Sahasranamam, V; Abraham, Annie

    2010-09-01

    Oxidative stress has long been recognized as an important mediator in the pathogenesis of cataract and the goal of this study was to determine the efficacy of isorhamnetin-3-glucoside (IR3G) in alleviating the toxicity induced by sodium selenite in in vitro culture condition. IR3G is the bioactive flavonoid isolated and characterized from the leaves of Cochlospermum religiosum. Enucleated rat lenses were maintained in organ culture containing M-199 medium alone (G-I), supplemented with 0.1 mM selenite (G-II) and selenite + 25 microg/ml IR3G (G-III). Treatment to G-III was from the second to fifth day while selenite administration to G-II & III was done on the third day. The antioxidant potential of the compound was assessed by Cu(2+) induced lipoprotein diene formation and superoxide scavenging assays. Morphological examination of the lenses also gave a supporting data. Antioxidant enzymes-superoxide dismutase (SOD), catalase and concentration of reduced glutathione (GSH) were significantly lower, while TBARS showed an increase in G-II than that in G-III and G-I lenses. Activity of Ca(2+)-ATPase was decreased and level of calcium was increased in G-II than G-III and G-I lenses. These data suggest that IR3G is able to significantly retard selenite cataract in vitro by virtue of its antioxidant property.

  4. Metabolism, excretion and avoidance of cyanogenic glucosides in insects with different feeding specialisations.

    PubMed

    Pentzold, Stefan; Zagrobelny, Mika; Bjarnholt, Nanna; Kroymann, Juergen; Vogel, Heiko; Olsen, Carl Erik; Møller, Birger Lindberg; Bak, Søren

    2015-11-01

    Cyanogenic glucosides (CNglcs) are widespread plant defence compounds releasing toxic hydrogen cyanide when hydrolysed by specific β-glucosidases after plant tissue damage. In contrast to specialist herbivores that have mechanisms to avoid toxicity from CNglcs, it is generally assumed that non-adapted herbivores are negatively affected by CNglcs. Recent evidence, however, implies that the defence potential of CNglcs towards herbivores may not be as effective as previously anticipated. Here, performance, metabolism and excretion products of insects not adapted to CNglcs were analysed, including species with different degrees of dietary specialisation (generalists, specialists) and different feeding modes (leaf-snipping lepidopterans, piercing-sucking aphids). Insects were reared either on cyanogenic or acyanogenic plants or on an artificial cyanogenic diet. Lepidopteran generalists (Spodoptera littoralis, Spodoptera exigua, Mamestra brassicae) were compared to lepidopteran glucosinolate-specialists (Pieris rapae, Pieris brassicae, Plutella xylostella), and a generalist aphid (Myzus persicae) was compared to an aphid glucosinolate-specialist (Lipaphis erysimi). All insects were tolerant to cyanogenic plants; in lepidopterans tolerance was mainly due to excretion of intact CNglcs. The two Pieris species furthermore metabolized aromatic CNglcs to amino acid conjugates (Cys, Gly, Ser) and derivatives of these, which is similar to the metabolism of benzylglucosinolates in these species. Aphid species avoided uptake of CNglcs during feeding. Our results imply that non-adapted insects tolerate plant CNglcs either by keeping them intact for excretion, metabolizing them, or avoiding uptake.

  5. Effects of ethyl-α-d-glucoside on human dermal fibroblasts.

    PubMed

    Bogaki, Takayuki; Mitani, Keiichi; Oura, Yuki; Ozeki, Kenji

    2017-09-01

    Ethyl α-d-glucoside (α-EG) is a glycoside present in sake, Japanese rice wine. Previous studies have reported that α-EG suppresses skin roughness after ultraviolet B irradiation, transepidermal water loss, and hepatic function disorder, and has a skin moisturizing effect. In this study, 0.48 μM of α-EG was found to increase the proliferation of normal human dermal fibroblasts (NHDF) by 121.0%, and the amount of collagen I produced by NHDF increased by 159.6% at an α-EG concentration of 0.048 μM, compared to those in cells cultured without α-EG. In NHDF cultured in α-EG-supplemented medium, the expression of fibroblast growth factor I and VII mRNA increased by 148.8 and 153.1%, at an α-EG concentration of 4.8 and 0.048 μM, respectively, as measured by a quantitative reverse transcription-polymerase chain reaction. Transcript levels of type I collagen genes, COL1A1 and COL1A2, increased by 152.4 and 129.7%, respectively, and that of a type III collagen gene, COL3A1, increased by 131.8% at an α-EG concentration of 0.48 μM. These findings supported the possibility that α-EG was involved in the maintenance and improvement of skin homeostasis and moisturizing functions.

  6. Effects of ethyl alpha-D-glucoside on skin barrier disruption.

    PubMed

    Kitamura, N; Ota, Y; Haratake, A; Ikemoto, T; Tanno, O; Horikoshi, T

    1997-01-01

    Daily treatments of skin in hairless mice with concentrates of rice wine, Japanese traditional alcohol, lowered transepidermal water loss levels compared to the controls on the 3rd day after ultraviolet B (UVB) irradiation. These findings indicate that the concentrates of rice wine suppress the murine skin barrier disruption caused by UVB. Ethyl alpha-D-glucoside (alpha-ethylglucoside), one of the peculiar components in rice wine, showed the same effect, whereas beta-ethylglucoside had no effect. In order to clarify the functions of alpha-ethylglucoside on murine skin, we examined the effects of this compound on the expression of some phenotypes in human keratinocytes in vitro. As a result, alpha-ethylglucoside as well as beta-ethylglucoside enhanced cell proliferation weakly, and the formation of cornified envelopes and differentiated type keratin (K1) in keratinocytes was accelerated by alpha-ethylglucoside but not by beta-ethylglucoside. From the results, we conclude that alpha-ethylglucoside enhanced the differentiation of keratinocytes, which might be related to reduced barrier disruption by UVB.

  7. Investigation of coco-glucoside as a novel intestinal permeation enhancer in rat models.

    PubMed

    Aguirre, Tanira A S; Rosa, Mónica; Guterres, Sílvia S; Pohlmann, Adriana R; Coulter, Ivan; Brayden, David J

    2014-11-01

    Due to instability in the GI tract and low intestinal permeability, peptides invariably have oral bioavailabilities below 1% and this has prevented the development of oral formulations. A mild plant-derived naturalalkyl polyglycoside (APG), coco-glucoside (CG), was studied for its capacity to enable rat intestinal permeation of the paracellular sugar marker, fluorescein isothiocyanate-dextran 4000 (FD4), across isolated rat jejunal and colonic mucosae mounted in Ussing chambers, as well as the polypeptide, salmon calcitonin (sCT) following intra-intestinal instillations in rats. 0.1% (w/v) CG enabled a 2.9-fold increase in the apparent permeability coefficient (Papp) of FD4 over the basal Papp across colonic mucosae, but it was without effect in jejunal mucosae. In situ intestinal instillations revealed that although sCT was absorbed across rat colonic loops to a greater extent than jejunal, CG still improved sCT absolute bioavailability(F) from both segments. Histopathology of rat intestinal mucosae following exposure to CG indicated only minor perturbation with adequate maintenance of secretory function. High content analysis(HCA) on Caco-2 showed that acute and chronic exposure to a range of concentrations of CG did not cause sub-lethal damage at concentrations at which it was effective as an enhancer. Overall, CG increased bioavailability of sCT across rat jejunal and colonic loops without indication of tissue damage. Thus, CG has potential as a safe and effective intestinal enhancer for oral delivery of proteins and peptides.

  8. Hopantenic acid beta-glucoside as a new urinary metabolite of calcium hopantenate in dogs.

    PubMed

    Nakano, K; Ando, H; Sugawara, Y; Ohashi, M; Harigaya, S

    1986-01-01

    The metabolism of calcium hopantenate (HOPA) was studied in beagle dogs. After oral administration of 14C-labeled HOPA, 25.5% of the administered radioactivity was excreted in the urine within 24 hr, mostly in the form of unchanged drug. The only metabolite, accounting for 4.2% of the radioactivity in the urine, was isolated by HPLC. The metabolite was hydrolyzed by the treatment of beta-glucuronidase (Helix pomatia), acid phosphatase, or beta-glucosidase. These enzyme activities were not inhibited by treatment with D-glucaric acid 1,4-lactone or PO4(3-), but with D-gluconic acid 1,5-lactone, demonstrating that the metabolite is a glucose conjugate. The compound was identified as HOPA-glucoside, 4'-O-(beta-D-glucopyranosyl)-D-hopantenic acid, by GC/MS analyses after derivatization of the metabolite and the synthetic compound. This is the first reported instance of glucose conjugation to a non-acidic hydroxyl group in the metabolism of xenobiotics in mammals.

  9. Transformation of rutin to antiproliferative quercetin-3-glucoside by Aspergillus niger.

    PubMed

    You, Hyun Ju; Ahn, Hyung Jin; Ji, Geun Eog

    2010-10-27

    The flavonol quercetin in plants and foods occurs predominantly in the form of glycoside whose sugar moiety affects the bioavailability and the mechanism of its biological activities. The antiproliferative activities of quercetin derivatives such as quercetin aglycone, quercetin-3-β-D-glucoside (Q3G), and rutin were compared using six different cancer cell lines including colon, breast, hepatocellular, and lung cancer. The IC50 value of Q3G ranged between 15 and 25 μM in HT-29, HCT 116, MCF-7, HepG2, and A549 cells. In these five cell lines, Q3G showed the most potent growth inhibition, whereas rutin showed the least potency. Transformation of rutin to Q3G was conducted by controlling α-L-rhamnosidase and β-D-glucosidase activities from crude enzyme extract of Aspergillus niger. Carbon sources during culture and transformation conditions such as pH, temperature, and heat-stability were optimized. After 4 h biotransformation, 99% of rutin was transformed to Q3G and no quercetin was detected. This study presented an efficient biotransformation for the conversion of rutin to Q3G which was newly shown to have more potent antiproliferative effect than quercetin and rutin.

  10. Analysis of Deoxynivalenol and Deoxynivalenol-3-glucoside in Hard Red Spring Wheat Inoculated with Fusarium Graminearum

    PubMed Central

    Ovando-Martínez, Maribel; Ozsisli, Bahri; Anderson, James; Whitney, Kristin; Ohm, Jae-Bom; Simsek, Senay

    2013-01-01

    Deoxynivalenol (DON) is a mycotoxin affecting wheat quality. The formation of the “masked” mycotoxin deoxinyvalenol-3-glucoside (D3G) results from a defense mechanism the plant uses for detoxification. Both mycotoxins are important from a food safety point of view. The aim of this work was to analyze DON and D3G content in inoculated near-isogenic wheat lines grown at two locations in Minnesota, USA during three different years. Regression analysis showed positive correlation between DON content measured with LC and GC among wheat lines, locality and year. The relationship between DON and D3G showed a linear increase until a certain point, after which the DON content and the D3G increased. Wheat lines having higher susceptibility to Fusarium showed the opposite trend. ANOVA demonstrated that the line and location have a greater effect on variation of DON and D3G than do their interaction among years. The most important factor affecting DON and D3G was the growing location. In conclusion, the year, environmental conditions and location have an effect on the D3G/DON ratio in response to Fusarium infection. PMID:24351715

  11. Cyanidin 3-glucoside improves diet-induced metabolic syndrome in rats.

    PubMed

    Bhaswant, Maharshi; Fanning, Kent; Netzel, Michael; Mathai, Michael L; Panchal, Sunil K; Brown, Lindsay

    2015-12-01

    Increased consumption of dark-coloured fruits and vegetables may mitigate metabolic syndrome. This study has determined the changes in metabolic parameters, and in cardiovascular and liver structure and function, following chronic administration of either cyanidin 3-glucoside (CG) or Queen Garnet plum juice (QG) containing cyanidin glycosides to rats fed either a corn starch (C) or a high-carbohydrate, high-fat (H) diet. Eight to nine-week-old male Wistar rats were randomly divided into six groups for 16-week feeding with C, C with CG or QG, H or H with CG or QG. C or H were supplemented with CG or QG at a dose of ∼ 8 mg/kg/day cyanidin glycosides from week 8 to 16. H rats developed signs of metabolic syndrome including visceral adiposity, impaired glucose tolerance, hypertension, cardiovascular remodelling, increased collagen deposition in left ventricle, non-alcoholic fatty liver disease, increased plasma liver enzymes and increased inflammatory cell infiltration in the heart and liver. Both CG and QG reversed these cardiovascular, liver and metabolic signs. However, no intact anthocyanins or common methylated/conjugated metabolites could be detected in the plasma samples and plasma hippuric acid concentrations were unchanged. Our results suggest CG is the most likely mediator of the responses to QG but that further investigation of the pharmacokinetics of oral CG in rats is required.

  12. Degradation kinetics of malvidin-3-glucoside and malvidin-3,5-diglucoside exposed to microwave treatment.

    PubMed

    Zhao, Mengyao; Li, Yuan; Xu, Xiayang; Wu, Jihong; Liao, Xiaojun; Chen, Fang

    2013-01-16

    Understanding the factors that contribute to the degradation of bioactive compounds during microwave treatment is meaningful for the practical application of this novel technology. The influence of microwave power, energy density, temperature, pH value, and initial concentration of anthocyanins (Acys) on the degradation behavior of malvidin-3-glucoside (Mv-3-glu) and malvidin-3,5-diglucoside (Mv-3,5-diglu) was investigated in this study. Results showed that the degradation of both Acys was accelerated with the increase of microwave power, energy density, temperature, pH value, and initial concentration of Acys. The degradation process of both Acys followed the first-order kinetics model (R² > 0.94), whereas the relationship between Acys degradation and energy density fitted to the logistic model well (R² > 0.98). In addition, Mv-3-glu was more susceptible to the microwave treatment than Mv-3,5-diglu. Compared with heating in a 98 ± 2 °C water bath, both Acys degraded more rapidly under microwave treatment at 100 °C, indicating the occurrence of microwave effect. The results provide a guide for the scientific application of microwave treatment.

  13. Disrupting Dimerization Translocates Soluble Epoxide Hydrolase to Peroxisomes.

    PubMed

    Nelson, Jonathan W; Das, Anjali J; Barnes, Anthony P; Alkayed, Nabil J

    2016-01-01

    The epoxyeicosatrienoic acid (EET) neutralizing enzyme soluble epoxide hydrolase (sEH) is a neuronal enzyme, which has been localized in both the cytosol and peroxisomes. The molecular basis for its dual localization remains unclear as sEH contains a functional peroxisomal targeting sequence (PTS). Recently, a missense polymorphism was identified in human sEH (R287Q) that enhances its peroxisomal localization. This same polymorphism has also been shown to generate weaker sEH homo-dimers. Taken together, these observations suggest that dimerization may mask the sEH PTS and prevent peroxisome translocation. In the current study, we test the hypothesis that dimerization is a key regulator of sEH subcellular localization. Specifically, we altered the dimerization state of sEH by introducing substitutions in amino acids responsible for the dimer-stabilizing salt-bridge. Green Fluorescent Protein (GFP) fusions of each of mutants were co-transfected into mouse primary cultured cortical neurons together with a PTS-linked red fluorescent protein to constitutively label peroxisomes. Labeled neurons were analyzed using confocal microscopy and co-localization of sEH with peroxisomes was quantified using Pearson's correlation coefficient. We find that dimer-competent sEH constructs preferentially localize to the cytosol, whereas constructs with weakened or disrupted dimerization were preferentially targeted to peroxisomes. We conclude that the sEH dimerization status is a key regulator of its peroxisomal localization.

  14. Formation of pyrimidine dimer radical anions in the gas phase.

    PubMed

    Edtbauer, Achim; Russell, Katherine; Feketeová, Linda; Taubitz, Jörg; Mitterdorfer, Christian; Denifl, Stephan; O'Hair, Richard A J; Märk, Tilmann D; Scheier, Paul; Wille, Uta

    2009-12-21

    Crossed-beam experiments revealed that attachment of a free electron to the cyclobutane pyrimidine dimers c,s-DMT<>DMT and c,a-DMT<>DMT leads to the formation of dimer radical anions with the lifetime of at least 80 micros, thus showing that the latter are much more stable than previously believed.

  15. A Wacky Bridge to mTORC1 Dimerization.

    PubMed

    Montagne, Jacques

    2016-01-25

    The activity of the mTORC1 protein complex depends on multiple metabolic inputs that regulate dimerization, recruitment to the lysosome, and activation. In this issue of Developmental Cell, David-Morrison et al. (2016) show that the Drosophila protein Wacky and its mammalian counterpart WAC act as adaptors in the process of mTORC1 dimerization.

  16. Targeting HOX/PBX dimers in cancer

    PubMed Central

    Morgan, Richard; El-Tanani, Mohamed; Hunter, Keith D.; Harrington, Kevin J.; Pandha, Hardev S.

    2017-01-01

    The HOX and PBX gene families encode transcription factors that have key roles in establishing the identity of cells and tissues in early development. Over the last 20 years it has become apparent that they are also dysregulated in a wide range of solid and haematological malignancies and have a predominantly pro-oncogenic function. A key mode of transcriptional regulation by HOX and PBX proteins is through their interaction as a heterodimer or larger complex that enhances their binding affinity and specificity for DNA, and there is growing evidence that this interaction is a potential therapeutic target in malignancies that include prostate, breast, renal, ovarian and lung cancer, melanoma, myeloma, and acute myeloid leukaemia. This review summarizes the roles of HOX and PBX genes in cancer and assesses the therapeutic potential of HOX/PBX dimer inhibition, including the availability of biomarkers for its application in precision medicine. PMID:28423659

  17. Targeting HOX/PBX dimers in cancer.

    PubMed

    Morgan, Richard; El-Tanani, Mohamed; Hunter, Keith D; Harrington, Kevin J; Pandha, Hardev S

    2017-05-09

    The HOX and PBX gene families encode transcription factors that have key roles in establishing the identity of cells and tissues in early development. Over the last 20 years it has become apparent that they are also dysregulated in a wide range of solid and haematological malignancies and have a predominantly pro-oncogenic function. A key mode of transcriptional regulation by HOX and PBX proteins is through their interaction as a heterodimer or larger complex that enhances their binding affinity and specificity for DNA, and there is growing evidence that this interaction is a potential therapeutic target in malignancies that include prostate, breast, renal, ovarian and lung cancer, melanoma, myeloma, and acute myeloid leukaemia. This review summarizes the roles of HOX and PBX genes in cancer and assesses the therapeutic potential of HOX/PBX dimer inhibition, including the availability of biomarkers for its application in precision medicine.

  18. Integrability of PT-symmetric dimers

    NASA Astrophysics Data System (ADS)

    Pickton, J.; Susanto, H.

    2013-12-01

    The coupled discrete linear and Kerr nonlinear Schrödinger equations with gain and loss describing transport on dimers with parity-time (PT)-symmetric potentials are considered. The model is relevant among others to experiments in optical couplers and proposals on Bose-Einstein condensates in PT-symmetric double-well potentials. It is known that the models are integrable. Here, the integrability is exploited further to construct the phase portraits of the system. A pendulum equation with a linear potential and a constant force for the phase difference between the fields is obtained, which explains the presence of unbounded solutions above a critical threshold parameter. The behavior of all solutions of the system, including changes in the topological structure of the phase plane, is then discussed.

  19. Three types of couplings between asymmetric plasmonic dimers.

    PubMed

    Chao, Yen-Chun; Tseng, Hsuan-Chi; Chang, Kao-Der; Chang, Chih-Wei

    2012-01-30

    We report extensive numerical studies on plasmonic dimers of different configurations and find that their coupling effects can be categorized into three types of phenomena. First, like ordinary mechanical systems, the plasmonic dimers can exhibit positive couplings that show anti-crossing behavior. Second, they can also be arranged to exhibit negative couplings that display opposite trends in resonant frequency shifts. Third, when there are surface currents in proximity to each other, the resonance frequencies of the dimers exhibit unusual redshifts that do not have any analogies in conventional systems. Our work suggests that in addition to the well-known electric and magnetic dipolar interactions, contributions from the inductance of displacement currents in the near field cannot be ignored. Overall, asymmetric plasmonic dimers exhibit better sensitivities than the symmetric counterparts and our extensive studies also enable us to identify the plasmonic dimer with the highest sensing capabilities.

  20. Photodissociable dimer reduction products of 2-thiopyrimidine derivatives.

    PubMed

    Wrona, M; Giziewicz, J; Shugar, D

    1975-12-01

    Both 4,6-dimethyl-2-thipyrimidine and its 1-methyl derivative undergo polarographic reduction in aqueous medium, via a 1e/1H+ reduction to a free radical which rapidly dimerizes to products isolates and identified as 4,4'-bis-(4,6-dimethyl-3,4-dihydropyrimidin-2-thione) and the corresponding 1-methyl dimer. The dimers may be oxidized electrolytically to regenerate the parent monomers. Both dimers also undergo photodissociation to quantitatively regenerate the parent monomers, in high quantum yield, 0.23 and 0.35 M/Einstein. The correlation between electrochemical and photochemical reductions of 2-thiopyrimidines are discussed, as well as the significance of the dimer photodissociation reactions in relation to nucleic acid photochemistry.

  1. Palladium dimers adsorbed on graphene: A DFT study

    NASA Astrophysics Data System (ADS)

    Kaur, Gagandeep; Gupta, Shuchi; Dharamvir, Keya

    2015-05-01

    The 2D structure of graphene shows a great promise for enhanced catalytic activity when adsorbed with palladium. We performed a systematic density functional theory (DFT) study of the adsorption of palladium dimer (Pd2) on graphene using SIESTA package, in the generalized gradient approximation (GGA). The adsorption energy, geometry, and charge transfer of Pd2-graphene system are calculated. Both horizontal and vertical orientations of Pd2 on graphene are studied. Our calculations revealed that the minimum energy configuration for Pd dimer is parallel to the graphene sheet with its two atoms occupying centre of adjacent hexagonal rings of graphene sheet. Magnetic moment is induced for Pd dimer adsorbed on graphene in vertical orientation while horizontal orientation of Pd dimer on graphene do not exhibit magnetism. Insignificant energy differences among adsorption sites means that dimer mobility on the graphene sheet is high. There is imperceptible distortion of graphene sheet perpendicular to its plane. However, some lateral displacements are seen.

  2. Structures of dimeric hydrolysis products of thorium.

    PubMed

    Wilson, Richard E; Skanthakumar, S; Sigmon, Ginger; Burns, Peter C; Soderholm, L

    2007-04-02

    Three unique thorium dimeric compounds have been crystallized from either direct hydrolysis of Th4+(aq)/HCl or titration of Th(OH)4(am) with Th(NO3)4(aq) and their structures determined using single-crystal X-ray diffraction. The compound [Th2(micro2-OH)2(NO3)6(H2O)6]H2O (1) is identical to that identified previously by Johansson. Two additional unreported compounds have been identified, [Th2(micro2-OH)2(NO3)4(H2O)8](NO3)2 (2) and [Th2(micro2-OH)2Cl2(H2O)12]Cl4.2H2O (3). 1 crystallizes in the monoclinic space group P21/c, with a = 6.792(2) A, b = 11.710(4) A, c = 13.778(5) A, and beta = 102.714(5) degrees and 2 crystallizes in the monoclinic space group P21/n, with a = 6.926(5) A, b = 7.207(1) A, c = 21.502(1) A, and beta = 96.380(1) degrees . The chloride-containing dimer, 3, crystallizes in triclinic P, with a = 8.080(2) A, b = 8.880(2) A, c = 9.013(2) A, alpha = 97.41(3) degrees , beta = 91.00(3), and gamma = 116.54(3) degrees . We also present high-energy X-ray scattering data demonstrating the presence of the hydroxo-bridged moiety in solution and discuss our findings in the context of known solid-state structures. The three structures demonstrate 11-, 10-, and 9-coordinate thorium, respectively, and coupled with the scattering experiments provide additional structural and chemical insight into tetravalent actinide hydrolysis.

  3. Molecular mechanisms of pyrimidine dimer excision in Saccharomyces cerevisiae: excision of dimers in cell extracts

    SciTech Connect

    Reynolds, R.J.; Love, J.D.; Friedberg, E.C.

    1981-08-01

    Cell-free extracts prepared from rad1-19, rad2-2, rad3-1, rad4-3, rad7-1, rad10-1, rad14-1, rad16-1, and cycl-1 (rad7) mutants of Saccharomyces cerevisiae all catalyze the preferential excision of thymine-containing pyrimidine dimers from ultraviolet-irradiated DNA specifically incised with M. luteus ultraviolet deoxyribonucleic acid incising activity.

  4. Dualism of Sensitivity and Selectivity of Porphyrin Dimers in Electroanalysis.

    PubMed

    Lisak, Grzegorz; Tamaki, Takashi; Ogawa, Takuji

    2017-04-04

    This work uncovers the application of porphyrin dimers for the use in electroanalysis, such as potentiometric determination of ions. It also puts in question a current perception of an occurrence of the super-Nernstian response, as a result of the possible dimerization of single porphyrins within an ion-selective membrane. To study that, four various porphyrin dimers were used as ionophores, namely, freebase-freebase, Zn-Zn, Zn-freebase, and freebase-Zn. Since the Zn-freebase and freebase-Zn porphyrin dimers carried both anion- and cation-sensitive porphyrin units, their application in ISEs was utilized in both anion- and cation-sensitive sensors. With respect to the lipophilic salt added, both porphyrins dimers were found anion- and cation-sensitive. This allowed using a single molecule as novel type of versatile ionophore (anion- and cation-selective), simply by varying the membrane composition. All anion-sensitive sensors were perchlorate-sensitive, while the cation-selective sensors were silver-sensitive. The selectivity of the sensors depended primarily on the porphyrin dimers in the ion-selective membrane. Furthermore, the selectivity of cation-sensitive dimer based sensors was found significantly superior to the ones measured for the single porphyrin unit based sensors (precursors of the porphyrin dimers). Thus, the dimerization of single porphyrins may actually be a factor to increase or modulate porphyrin selectivity. Moreover, in the case of cation-sensitive sensors, the selectivity vastly depended on the order of porphyrin units in the dimer. This opens a new approach of regulating and adjusting sensitivity and selectivity of the sensor through the application of complex porphyrin systems with more than one porphyrin units with mix sensitive porphyrins.

  5. Synthesis of misfolded glycoprotein dimers through native chemical ligation of a dimeric peptide thioester.

    PubMed

    Izumi, Masayuki; Komaki, Shinji; Okamoto, Ryo; Seko, Akira; Takeda, Yoichi; Ito, Yukishige; Kajihara, Yasuhiro

    2016-07-07

    Glycoprotein quality control processes are very important for an efficient production of glycoproteins and for avoiding the accumulation of unwanted toxic species in cells. These complex processes consist of multiple enzymes and chaperones such as UGGT, calnexin/calreticulin, and glucosidase II. We designed and synthesized monomeric and dimeric misfolded glycoprotein probes. Synthetic homogeneous monomeric glycoproteins proved to be useful substrates for kinetic analyses of the folding sensor enzyme UGGT. For a concise synthesis of a bismaleimide-linked dimer, we examined double native chemical ligation (dNCL) of a dimeric peptide-α-thioester. The dNCL to two equivalents of glycopeptides gave a homodimer. The dNCL to a 1 : 1 mixture of a glycopeptide and a non-glycosylated peptide gave all the three possible ligation products consisting of two homodimers and a heterodimer. Both the homodimer bearing two Man9GlcNAc2 (M9) oligosaccharides and the heterodimer bearing one M9 oligosaccharide were found to be good substrates of UGGT.

  6. Pi-dimer of an aniline dimer: an ESR-UV-vis spectroelectrochemical study.

    PubMed

    Petr, Andreas; Wei, Di; Kvarnström, Carita; Ivaska, Ari; Dunsch, Lothar

    2007-11-01

    It is shown for the first time that the most important intermediate formed during aniline polymerization, the p-aminodiphenylamine, forms a pi-dimer under oxidation at room temperature in acidified organic solvents that are used in electropolymerization. N-Phenylquinonediimine, which is generally assumed to be formed under oxidation, is only formed in basic solutions and in ionic liquids. Most of the mechanistic studies reported so far take the formation of N-phenylquinonediimine under consideration, although it is not consistent with the UV-vis spectra measured during oxidation of p-aminodiphenylamine. The formation of a pi-dimer is very well consistent with the electronic spectra of the oxidation product. In this way the pi-dimer is very important for the interpretation of the UV-vis spectra of higher oligomers and polyaniline as well. Furthermore, it offers a new interpretation of the redox behavior of p-aminodiphenylamine as found by cyclic voltammetry and has to be considered in the mechanism of the electrochemical polyaniline formation.

  7. Multiple α-Glucoside Transporter Genes in Brewer’s Yeast

    PubMed Central

    Jespersen, Lene; Cesar, Lene B.; Meaden, Philip G.; Jakobsen, Mogens

    1999-01-01

    Maltose and maltotriose are the two most abundant fermentable sugars in brewer’s wort, and the rate of uptake of these sugars by brewer’s yeast can have a major impact on fermentation performance. In spite of this, no information is currently available on the genetics of maltose and maltotriose uptake in brewing strains of yeast. In this work, we studied 30 brewing strains of yeast (5 ale strains and 25 lager strains) with the aim of examining the alleles of maltose and maltotriose transporter genes contained by them. To do this, we hybridized gene probes to chromosome blots. Studies performed with laboratory strains have shown that maltose utilization is conferred by any one of five unlinked but highly homologous MAL loci (MAL1 to MAL4 and MAL6). Gene 1 at each locus encodes a maltose transporter. All of the strains of brewer’s yeast examined except two were found to contain MAL11 and MAL31 sequences, and only one of these strains lacked MAL41. MAL21 was not present in the five ale strains and 12 of the lager strains. MAL61 was not found in any of the yeast strains. In three of the lager strains, there was evidence that MAL transporter gene sequences occurred on chromosomes other than those known to carry MAL loci. Sequences corresponding to the AGT1 gene, which encodes a transporter of several α-glucosides, including maltose and maltotriose, were detected in all but one of the yeast strains. Homologues of AGT1 were identified in three of the lager strains, and two of these homologues were mapped, one to chromosome II and the other to chromosome XI. AGT1 appears to be a member of a family of closely related genes, which may have arisen in brewer’s yeast in response to selective pressure. PMID:9925567

  8. Dietary cyanidin 3-glucoside from purple corn ameliorates doxorubicin-induced cardiotoxicity in mice.

    PubMed

    Petroni, K; Trinei, M; Fornari, M; Calvenzani, V; Marinelli, A; Micheli, L A; Pilu, R; Matros, A; Mock, H-P; Tonelli, C; Giorgio, M

    2017-05-01

    Anthracyclines are effective anticancer drugs that have improved prognosis of hundred thousand cancer patients worldwide and are currently the most common chemotherapeutic agents used for the treatment of blood, breast, ovarian and lung cancers. However, their use is limited because of a cumulative dose-dependent and irreversible cardiotoxicity that can cause progressive cardiomyopathy and congestive heart failure. Aim of the present study was to determine the cardioprotective activity of a dietary source of cyanidin 3-glucoside (C3G), such as purple corn, against doxorubicin (DOX)-induced cardiotoxicity in mice. In vitro studies on murine HL-1 cardiomyocytes showed that pretreatment with both pure C3G and purple corn extract improved survival upon DOX treatment. However, C3G and purple corn extract did not affect the cytotoxic effect of DOX on human cancer cell lines. We then validated in vivo the protective role of a C3G-enriched diet against DOX-induced cardiotoxicity by comparing the effect of dietary consumption of corn isogenic lines with high levels of anthocyanins (purple corn - Red diet - RD) or without anthocyanins (yellow corn - Yellow diet - YD) incorporated in standard rodent diets. Results showed that mice fed RD survived longer than mice fed YD upon injection of a toxic amount of DOX. In addition, ultrastructural analysis of hearts from mice fed RD showed reduced histopathological alterations. Dietary intake of C3G from purple corn protects mice against DOX-induced cardiotoxicity. Copyright © 2017 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.

  9. The inhibition of macrophage foam cell formation by tetrahydroxystilbene glucoside is driven by suppressing vimentin cytoskeleton.

    PubMed

    Yao, Wenjuan; Huang, Lei; Sun, Qinju; Yang, Lifeng; Tang, Lian; Meng, Guoliang; Xu, Xiaole; Zhang, Wei

    2016-10-01

    Macrophage foam cell formation triggered by oxLDL is an important event that occurs during the development of atherosclerosis. 2,3,5,4'-Tetrahydroxystilbene-2-O-β-d-glucoside (TSG) exhibits significant anti-atherosclerotic activity. Herein we used U937 cells induced by PMA and oxLDL in vitro to investigate the inhibitory effects of TSG on U937 differentiation and macrophage foam cell formation. TSG pretreatment markedly inhibited cell differentiation induced by PMA, macrophage apoptosis and foam cell formation induced by oxLDL. The inhibition of vimentin expression and cleavage was involved in these inhibitory effects of TSG. The suppression of vimentin by siRNA in U937 significantly inhibited cell differentiation, apoptosis and foam cell formation. Using inhibitors for TGFβR1 and PI3K, we found that vimentin production in U937 cells is regulated by TGFβ/Smad signaling, but not by PI3K-Akt-mTOR signaling. Meanwhile, TSG pretreatment inhibited both the expression of TGFβ1 and the phosphorylation of Smad2 and Smad3, and TSG suppressed the nuclear translocation of Smad4 induced by PMA and oxLDL. Furthermore, TSG attenuated the induced caspase-3 activation and adhesion molecules levels by PMA and oxLDL. PMA and oxLDL increased the co-localization of vimentin with ICAM-1, which was attenuated by pretreatment with TSG. These results suggest that TSG inhibits macrophage foam cell formation through suppressing vimentin expression and cleavage, adhesion molecules expression and vimentin-ICAM-1 co-localization. The interruption of TGFβ/Smad pathway and caspase-3 activation is responsible for the downregulation of TSG on vimentin expression and degradation, respectively.

  10. Hepatic and gastrointestinal first-pass effects of vitexin-4″-O-glucoside in rats.

    PubMed

    Chen, Yinghui; Zhang, Wenjie; Li, Di; Ai, Junjun; Meng, Yihan; Ying, Xixiang; Kang, Tingguo

    2013-10-01

    This paper was to clarify the reasons of low bioavailability of vitexin-4″-O-glucoside (VOG) in rats via hepatic combined with gastrointestinal first-pass effect. Observed the hepatic first-pass effect through the comparison of area under the plasma concentration-time curve from zero to infinity (AUC0→∞ ) of VOG in arterial plasma after femoral and portal vein administration (10 mg/kg), similarly, evaluated the gastrointestinal first-pass effect after portal vein (10 mg/kg) and gastrointestinal administration (20 mg/kg). For the study on regulatory mechanisms of cytochrome P450 3A (CYP3A) and P-glycoprotein (P-gp) on the bioavailability of VOG, the solution of verapamil hydrochloride (60 mg/kg) was instilled into intestine at 10 min before the infusion of VOG. The bioavailability of VOG after intraportal, intestinal as well as gastric administration was 45.1%, 8.1% and 9.8%, respectively. The value of AUC0→∞ for verapamil group was approximately 1.4-fold higher than that for normal saline group, meaning that perhaps CYP3A participated in the metabolism of VOG or P-gp transported VOG outside. The hepatic and intestinal first-pass effect were considered to mostly contribute to the low bioavailability of VOG in rats, and the gastric first-pass effect should be neglected. Also, the contribution of CYP3A to metabolism and P-gp mediated efflux have played a significant role in low bioavailability of VOG. © 2013 Royal Pharmaceutical Society.

  11. Anhydrous octyl-glucoside phase transition from lamellar to isotropic induced by electric and magnetic fields

    NASA Astrophysics Data System (ADS)

    Hashim, Rauzah; Sugimura, Akihiko; Nguan, Hock-Seng; Rahman, Matiur; Zimmermann, Herbert

    2017-02-01

    A static deuterium nuclear magnetic resonance (2HNMR) technique (magnetic field, B = 7.05 T) was employed to monitor the thermotropic lamellar phase of the anhydrous 1:1 mixture sample of octyl-b-D-glucoside (βOG) and that of partially deuterium labelled at the alpha position on the chain, i.e.,βOG-d2 In the absence of an electric field, the 2H NMR spectrum of the mixture gives a typical quadrupolar doublet representing the aligned lamellar phase. Upon heating to beyond the clearing temperature at 112 °C, this splitting converts to a single line expected for an isotropic phase. Simultaneous application of magnetic and electric fields (E = 0.4 MV/m) at 85 °C in the lamellar phase, whose direction was set to be parallel or perpendicular to the magnetic field, resulted in the change of the doublet into a single line and this recovers to the initial doublet with time for both experimental geometries. This implies E- and B-field-induced phase transitions from the lamellar to an isotropic phase and a recovery to the lamellar phase again with time. Moreover, these phase transformations are accompanied by a transient current. A similar observation was made in a computational study when an electric field was applied to a water cluster system. Increasing the field strength distorts the water cluster and weakens its hydrogen bonds leading to a structural breakdown beyond a threshold field-strength. Therefore, we suggest the observed field-induced transition is likely due to a structure change of the βOG lamellar assembly caused by the field effect and not due to Joule heating.

  12. Effects of Power Ultrasound on Stability of Cyanidin-3-glucoside Obtained from Blueberry.

    PubMed

    Yao, Guang-Long; Ma, Xing-Hui; Cao, Xian-Yin; Chen, Jian

    2016-11-18

    Power ultrasound (US) could potentially be used in the food industry in the future. However, the extent of anthocyanin degradation by US requires investigation. Cyanidin-3-glucoside (Cy-3-glu) obtained from blueberry extracts was used as research material to investigate the effect of power ultrasound on food processing of anthocyanin-rich raw materials. The effects of ultrasonic waves on the stability of Cy-3-glu and on the corresponding changes in UV-Vis spectrum and antioxidant activity were investigated, and the mechanisms of anthocyanin degradation induced by ultrasonic waves were discussed. To explore Cy-3-glu degradation in different environments, we kept the Cy-3-glu solution treated with ultrasonic waves in four concentrations (0%, 10%, 20%, and 50%) of ethanol aqueous solutions to simulate water, beer, wine, and liquor storage environment according to the chemical kinetics method. Results show that the basic spectral characteristics of Cy-3-glu did not significantly change after power ultrasound cell crusher application at 30 °C. However, with anthocyanin degradation, the intensity of the peak for Cy-3-glu at 504 nm significantly decreased (p < 0.05). The degradation kinetics of Cy-3-glu by ultrasonic waves (200-500 W frequency) fitted well to first-order reaction kinetics, and the degradation rate constant of Cy-3-glu under power ultrasound was considerably larger than that under thermal degradation (p < 0.05). The sensitivity of the anthocyanins of blueberry to temperature increased with increasing ethanol concentration, and the longest half-life was observed in 20% ethanol aqueous solution.

  13. Total glucosides of paeony prevents juxta-articular bone loss in experimental arthritis

    PubMed Central

    2013-01-01

    Background Total glucosides of paeony (TGP) is a biologically active compound extracted from Paeony root. TGP has been used in rheumatoid arthritis therapy for many years. However, the mechanism by which TGP prevents bone loss has been less explored. Methods TGP was orally administered for 3 months to New Zealand rabbits with antigen-induced arthritis (AIA). Digital x-ray knee images and bone mineral density (BMD) measurements of the subchondral knee bone were performed before sacrifice. Chondrocytes were observed using transmission electron microscopy (TEM). Histological analysis and mRNA expression of receptor activator of nuclear factor-B ligand (RANKL) and osteoprotegerin (OPG) were evaluated in joint tissues. Results The BMD value in TGP rabbits was significantly higher compared with that seen in the AIA model rabbits. In addition, the subchondral bone plate was almost completely preserved by TGP treatment, while there was a decrease in bone plate integrity in AIA rabbits. There was less damage to the chondrocytes of the TGP treated group. Immunohistochemical examination of the TGP group showed that a higher percentage of TGP treated chondrocytes expressed OPG as compared to the chondrocytes isolated from AIA treated animals. In contrast, RANKL expression was significantly decreased in the TGP treated group compared to the AIA group. In support of the immunohistochemistry data, the expression of RANKL mRNA was decreased and OPG mRNA expression was enhanced in the TGP group when compared to that of the AIA model group. Conclusion These results reveal that TGP suppresses juxta-articular osteoporosis and prevents subchondral bone loss. The decreased RANKL and increased OPG expression seen in TGP treated animals could explain how administration of TGP maintains higher BMD. PMID:23870279

  14. Intestinal toxicity of the masked mycotoxin deoxynivalenol-3-β-D-glucoside.

    PubMed

    Pierron, Alix; Mimoun, Sabria; Murate, Leticia S; Loiseau, Nicolas; Lippi, Yannick; Bracarense, Ana-Paula F L; Liaubet, Laurence; Schatzmayr, Gerd; Berthiller, Franz; Moll, Wulf-Dieter; Oswald, Isabelle P

    2016-08-01

    Natural food contaminants such as mycotoxins are an important problem for human health. Deoxynivalenol (DON) is one of the most common mycotoxins detected in cereals and grains. Its toxicological effects mainly concern the immune system and the gastrointestinal tract. This toxin is a potent ribotoxic stressor leading to MAP kinase activation and inflammatory response. DON frequently co-occurs with its glucosylated form, the masked mycotoxin deoxynivalenol-3-β-D-glucoside (D3G). The toxicity of this later compound remains unknown in mammals. This study aimed to assess the ability of D3G to elicit a ribotoxic stress and to induce intestinal toxicity. The toxicity of D3G and DON (0-10 µM) was studied in vitro, on the human intestinal Caco-2 cell line, and ex vivo, on porcine jejunal explants. First, an in silico analysis revealed that D3G, contrary to DON, was unable to bind to the A-site of the ribosome peptidyl transferase center, the main targets for DON toxicity. Accordingly, D3G did not activate JNK and P38 MAPKs in treated Caco-2 cells and did not alter viability and barrier function on cells, as measured by the trans-epithelial electrical resistance. Treatment of intestinal explants for 4 h with 10 µM DON induced morphological lesions and up-regulated the expression of pro-inflammatory cytokines as measured by qPCR and pan-genomic microarray analysis. By contrast, expression profile of D3G-treated explants was similar to that of controls, and these explants did not show histomorphology alteration. In conclusion, our data demonstrated that glucosylation of DON suppresses its ability to bind to the ribosome and decreases its intestinal toxicity.

  15. Anhydrous octyl-glucoside phase transition from lamellar to isotropic induced by electric and magnetic fields.

    PubMed

    Hashim, Rauzah; Sugimura, Akihiko; Nguan, Hock-Seng; Rahman, Matiur; Zimmermann, Herbert

    2017-02-28

    A static deuterium nuclear magnetic resonance ((2)HNMR) technique (magnetic field, B = 7.05 T) was employed to monitor the thermotropic lamellar phase of the anhydrous 1:1 mixture sample of octyl-b-D-glucoside (βOG) and that of partially deuterium labelled at the alpha position on the chain, i.e.,βOG-d2 In the absence of an electric field, the (2)H NMR spectrum of the mixture gives a typical quadrupolar doublet representing the aligned lamellar phase. Upon heating to beyond the clearing temperature at 112 °C, this splitting converts to a single line expected for an isotropic phase. Simultaneous application of magnetic and electric fields (E = 0.4 MV/m) at 85 °C in the lamellar phase, whose direction was set to be parallel or perpendicular to the magnetic field, resulted in the change of the doublet into a single line and this recovers to the initial doublet with time for both experimental geometries. This implies E- and B-field-induced phase transitions from the lamellar to an isotropic phase and a recovery to the lamellar phase again with time. Moreover, these phase transformations are accompanied by a transient current. A similar observation was made in a computational study when an electric field was applied to a water cluster system. Increasing the field strength distorts the water cluster and weakens its hydrogen bonds leading to a structural breakdown beyond a threshold field-strength. Therefore, we suggest the observed field-induced transition is likely due to a structure change of the βOG lamellar assembly caused by the field effect and not due to Joule heating.

  16. Leaching of cyanogenic glucosides and cyanide from white clover green manure.

    PubMed

    Bjarnholt, Nanna; Laegdsmand, Mette; Hansen, Hans C B; Jacobsen, Ole H; Møller, Birger Lindberg

    2008-06-01

    Use of crops for green manure as a substitute for chemical fertilizers and pesticides is an important approach towards more sustainable agricultural practices. Green manure from white clover is rich in nitrogen but white clover also produces the cyanogenic glucosides (CGs) linamarin and lotaustralin; CGs release toxic hydrogen cyanide (HCN) upon hydrolysis which may be utilized for pest control. We demonstrate that applying CGs in the form of a liquid extract of white clover to large columns of intact agricultural soils can result in leaching of toxic cyanide species to a depth of at least 1m. Although degradation of the CGs during leaching proceeded with half lives in the interval 1.5-35 h depending on soil characteristics, a fraction of the applied CGs (0.9-3.2%) was recovered in the leachate as either CGs or toxic cyanide species. Detoxification of the HCN formed was rapid in soil and leachate from both sandy and loamy soil. However, 30% of the leachate samples exceeded the EU threshold value of 50 micrgl(-1) total cyanide for drinking water and 85% exceeded the US threshold of 5 micrgl(-1) for cyanide chronic ecotoxicity in fresh water. This study demonstrates that even easily degradable natural products present in crop plants as defense compounds pose a threat to the quality of groundwater and surface waters. This aspect needs consideration in assessment of the risk associated with use of crops as green manure to replace chemical fertilizers and pesticides as well as in genetic engineering approaches to design crops with improved pest resistance.

  17. Trihydroxybenzoic acid glucoside as a global skin color modulator and photo-protectant

    PubMed Central

    Chajra, Hanane; Redziniak, Gérard; Auriol, Daniel; Schweikert, Kuno; Lefevre, Fabrice

    2015-01-01

    Background 3,4,5-Trihydroxybenzoic acid glucoside (THBG), a molecule produced by an original biocatalysis-based technology, was assessed in this study with respect to its skin photoprotective capacity and its skin color control property on Asian-type skin at a clinical level and on skin explant culture models. Methods The double-blinded clinical study was done in comparison to a vehicle by the determination of objective color parameters thanks to recognized quantitative and qualitative analysis tools, including Chroma-Meter, VISIA-CR™, and SIAscope™. Determination of L* (brightness), a* and b* (green–red and blue–yellow chromaticity coordinates), individual typology angle, and C* (chroma) and h* (hue angle) parameters using a Chroma-Meter demonstrated that THBG is able to modify skin color while quantification of ultraviolet (UV) spots by VISIA-CR™ confirmed its photoprotective effect. The mechanism of action of THBG molecule was determined using explant skin culture model coupled to histological analysis (epidermis melanin content staining). Results We have demonstrated that THBG was able to modulate significantly several critical parameters involved in skin color control such as L* (brightness), a* (redness), individual typology angle (pigmentation), and hue angle (yellowness in this study), whereas no modification occurs on b* and C* parameters. We have demonstrated using histological staining that THBG decrease epidermis melanin content under unirradiated and irradiated condition. We also confirmed that THBG molecule is not a sunscreen agent. Conclusion This study demonstrated that THBG controls skin tone via the inhibition of melanin synthesis as well as the modulation of skin brightness, yellowness, and redness. PMID:26648748

  18. Enhancement of volatile aglycone recovery facilitated by acid hydrolysis of glucosides from Nicotiana flower species.

    PubMed

    Coleman, William M; Dube, Michael F; Gerardi, Anthony R; Ashraf-Khorassani, Mehdi; Taylor, Larry T

    2012-11-21

    Four different Nicotiana flowers (Nicotiana alata (alata), Nicotiana sylvestris (Sy), Nicotiana suaveolens (Su), and Nicotiana tabacum cv. Flue-Cured (FC)) from farms in Virginia and North Carolina were harvested and promptly quenched with liquid nitrogen and hand-ground prior to analysis. Each Nicotiana flower was pre-extracted with hexane to remove unbound volatiles. Fifteen standard compounds that were thought to be in the pre-extract were employed to aid in GC-MS identification and quantification. Glucosides were then chromatographically isolated and next hydrolyzed via 2 M sulfuric acid for 24 h at 75 °C. For each flower, the products of hydrolysis were extracted in tandem with hexane and dichloromethane (DCM) prior to analysis by GC-MS. The mixture of hexane and DCM extracts of the flowers after hydrolysis were then analyzed for each of 15 external standards via GC-MS to determine the concentration of any isolated flower-derived aglycone. Quantitative results for each of the possible 15 free volatile compounds extracted before and after hydrolysis were compared. Benzyl alcohol, phenethyl alcohol, and cis-3-hexenol were found in all Nicotiana both before and after acid hydrolysis. Enormous increases in the mass of benzyl alcohol and phenethyl alcohol were obtained with all flowers as a result of acid hydrolysis. With selected Nicotiana flowers, significant increases were observed for eugenol and cinnamaldehyde. The significant increases observed in cinnamaldehyde and eugenol upon mild acid hydrolysis strongly indicate that this approach could be a viable alternative process for the production scale isolation of these important natural flavor compounds.

  19. Maintenance of cold-preserved porcine hepatocyte function with UW solution and ascorbic acid-2 glucoside.

    PubMed

    Takesue, Michihiko; Maruyama, Masanobu; Shibata, Norikuni; Kunieda, Takemi; Okitsu, Teru; Sakaguchi, Masakiyo; Totsugawa, Toshinori; Kosaka, Yoshikazu; Arata, Akira; Ikeda, Hideaki; Matsuoka, Junji; Oyama, Toshie; Kodama, Makoto; Ohmoto, Kenji; Yamamoto, Shinichiro; Kurabayashi, Yuzuru; Yamamoto, Itaru; Tanaka, Noriaki; Kobayashi, Naoya

    2003-01-01

    Normal human hepatocytes are an ideal source of liver-targeted cell therapies, such as hepatocyte transplantation and bioartificial livers, but availability of human donor livers for liver cell isolation is severely limited. To effectively utilize scarce donor organs for cell therapies, it is of extreme importance to establish an efficient isolation technique and an effective cold preservation solution for transportation of isolated cells. A lateral segment of the liver was surgically resected from pigs weighing 10 kg and a four-step collagenase and dispase digestion was conducted. Isolated hepatocytes were subjected to 8-h cold storage on ice. The following preservation solutions were tested: 1) University of Wisconsin (UW) solution, 2) UW with 100 microg/ml of ascorbic acid-2 glucoside (AA2G), 3) 100% fetal bovine serum (FBS), and 4) Dulbecco's modified Eagle's medium (DMEM) supplemented with 100% FBS. The mean viability of porcine hepatocytes was 95.5 +/- 2.5% when isolated in three independent experiments. Viability, plating efficiency, membrane stability, and ammonia metabolic capacity of cold-preserved hepatocytes were significantly better maintained by the use of UW solution. When AA2G (100 microg/ml) was combined with UW solution, such parameters were further improved. It was explained by inhibition of caspase-3 activation and retention of ATP at high levels of hepatocytes preserved with UW solution containing AA2G. The present work demonstrates that a combination of UW solution with AA2G (100 microg/ml) would be a useful cold preservation means for the development of cell therapies.

  20. Functional diversification of two UGT80 enzymes required for steryl glucoside synthesis in Arabidopsis

    PubMed Central

    Stucky, Daniel F.; Arpin, James C.

    2015-01-01

    Steryl glucosides (SG) are abundant steroid conjugates in plant membranes. Beyond structural roles in lipid bilayers, functions in sugar transport, storage, and/or signalling are predicted. UDP-glucose:sterol glucosyltransferase 80A2 (UGT80A2) and UGT80B1, which share similarity to fungal counterparts, are implicated in SG synthesis in Arabidopsis thaliana. A third related enzyme, which seems specific to the plant lineage, is encoded by UGT713B1/At5g24750. Genetic and biochemical approaches were employed to determine the role of each UGT gene in the production of specific SGs and acyl SGs (ASGs). Using direct infusion electrospray ionization tandem mass spectrometry (ESI-MS/MS), SG and acyl SG (ASG) contents of ugt80 and ugt713 mutants, and triple and double mutants were profiled in seeds. In vitro enzyme assays were performed to assay substrate preferences. Both UGT80A2 and UGT80B1, but not UGT713B1 were shown to be coordinately down-regulated during seed imbibition when SG levels decline, consistent with similar functions as UGT80 enzymes. UGT80A2 was found to be required for normal levels of major SGs in seeds, whereas UGT80B1 is involved in accumulation of minor SG and ASG compounds. Although the results demonstrate specific activities for UGT80A2 and UGT80B1, a role for UGT713B1 in SG synthesis was not supported. The data show that UGT80A2, the more highly conserved enzyme, is responsible for the bulk production of SGs in seeds, whereas UGT80B1 plays a critical accessory role. This study extends our knowledge of UGT80 enzymes and provides evidence for specialized functions for distinct classes of SG and ASG molecules in plants. PMID:25316063

  1. Dispersion of Vesicles Composed of Industrially Produced Alkyl (Oligo) Glucoside Using Diol-Boron Complexation.

    PubMed

    Aikawa, Tatsuo; Asano, Yuuka; Kondo, Takeshi; Yuasa, Makoto

    2016-07-01

    Alkyl (oligo)glucosides (AOG) are known to be environmentally compatible amphiphiles whose commercial applicability should be broadened. The present paper describes the preparation of molecular assemblies of industrially produced AOG, which is a mixture composed of different length of alkyl chains (C9-C12) with oligoglucoside moiety with a few (1-3) of glucose units. It was also described that regulation of the dispersibility of the molecular assemblies prepared by diol-boron complexation between the sugar moiety on AOG and boric acid in a dispersion medium. The molecular assembly of AOG was successfully formed by mixing AOG and cholesterols (CH). When using a suitable amount of CH (20-40 mol% with respect to AOG), the molecular assembly formed a vesicle structure. The dispersion ability of the resulting vesicle was dependent on both the boric acid concentration and pH of the dispersion medium. The light-scattering and ζ-potential measurements revealed that high concentrations (≥10 mM) of boric acid improved dispersibility the vesicles. In contrast, the vesicle agglomerated at low concentrations of boric acid (1-7.5 mM). In the absence of boric acid in dispersion medium, the vesicles were completely agglomerated. The optimum pH range for vesicle dispersion was found to be from neutral to basic (7.4-10.1). The (11)B NMR study revealed that borate ester formation occurred between boric acid and the diol of the sugar moiety on AOG vesicle. The present data suggest that borate ester formation that occurred on the surface of the vesicle provided negative charge to the vesicles, contributing to their dispersion via repulsive forces.

  2. Apigenin-7-O-glucoside oxidation catalyzed by P450-bioinspired systems.

    PubMed

    Bolzon, Lucas B; Dos Santos, Joicy S; Silva, Denise B; Crevelin, Eduardo J; Moraes, Luiz A B; Lopes, Norberto P; Assis, Marilda D

    2017-05-01

    Apigenin-7-O-glucoside (A7G) is the main flavonoid of Bidens gardneri Bak., a Brazilian plant with wide application in folk medicine. Despite the popular use of this plant, its biological effects are not completely known. This work tested the 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin iron(III) and manganese(III) chloride (Fe(TFPP)Cl and Mn(TFPP)Cl), and Jacobsen's catalyst as P450-bioinspired catalysts for A7G oxidation by different oxidants (PhIO, H2O2, m-CPBA, and t-BuOOH). Up to nine different products were detected by HPLC analysis; Reactions with metalloporphyrin/PhIO systems afforded high catalytic conversions (58-89%). In spite of providing smaller product yields, the metalloporphyrin/H2O2 systems led to superior product distribution. Fe(TFPP)Cl yielded the highest A7G conversion rates (79-93%) with the four different oxidants tested herein. In the presence of PhIO, the oxidative profile of the manganese catalysts was very close to the oxidative profile of Fe(TFPP)Cl. However, in medium containing peroxide, the reactivity of the manganese catalysts was lower as compared to the reactivity of Fe(TFPP)Cl. Reactions with Fe(TFPP)Cl/oxidant systems were analyzed by UPLC-MS; up to thirteen compounds were detected. A7G oxidation catalyzed by Fe(TFPP)Cl yielded seven compounds. Three other compounds had m/z profile compatible with the profile of the A7G metabolites. The A7G oxidation assays performed in the presence of P450-bioinspired catalysts demonstrated their great catalytic potential toward A7G. The present results may be useful to many areas of knowledge and to the research and development of numerous chemical and phamarcological processes, especially in terms of drug design, biological assays, and applications in medicinal chemistry.

  3. Plant growth inhibition by cis-cinnamoyl glucosides and cis-cinnamic acid.

    PubMed

    Hiradate, Syuntaro; Morita, Sayaka; Furubayashi, Akihiro; Fujii, Yoshiharu; Harada, Jiro

    2005-03-01

    Spiraea thunbergii Sieb. contains 1-O-cis-cinnamoyl-beta-D-glucopyranose (CG) and 6-O-(4'-hydroxy-2'-methylene-butyroyl)-1-O-cis-cinnamoyl-beta-D-glucopyranose (BCG) as major plant growth inhibiting constituents. In the present study, we determined the inhibitory activity of CG and BCG on root elongation of germinated seedlings of lettuce (Lactuca sativa), pigweed (Amaranthus retroflexus), red clover (Trifolium pratense), timothy (Phleum pratense), and bok choy (Brassica rapa var chinensis) in comparison with that of two well-known growth inhibitors, 2,4-dichlorophenoxyacetic acid (2,4-D) and (+)-2-cis-4-trans-abscisic acid (cis-ABA), as well as two related chemicals of CG and BCG, cis-cinnamic acid (cis-CA) and trans-cinnamic acid (trans-CA). The EC50 values for CG and BCG on lettuce were roughly one-half to one-quarter of the value for cis-ABA. cis-Cinnamic acid, which is a component of CG and BCG, possessed almost the same inhibitory activity of CG and BCG, suggesting that the essential chemical structure responsible for the inhibitory activity of CG and BCG is cis-CA. The cis-stereochemistry of the methylene moiety is apparently needed for high inhibitory activity, as trans-CA had an EC50 value roughly 100 times that of CG, BCG, and cis-CA. Growth inhibition by CG, BCG, and cis-CA was influenced by the nature of the soil in the growing medium: alluvial soil preserved the bioactivity, whereas volcanic ash and calcareous soils inhibited bioactivity. These findings indicate a potential role of cis-CA and its glucosides as allelochemicals for use as plant growth regulators in agricultural fields.

  4. Eriodictyol-7-O-glucoside activates Nrf2 and protects against cerebral ischemic injury

    SciTech Connect

    Jing, Xu; Ren, Dongmei; Wei, Xinbing; Shi, Huanying; Zhang, Xiumei; Perez, Ruth G.; Lou, Haiyan; Lou, Hongxiang

    2013-12-15

    Stroke is a complex disease that may involve oxidative stress-related pathways in its pathogenesis. The nuclear factor erythroid-2-related factor 2/antioxidant response element (Nrf2/ARE) pathway plays an important role in inducing phase II detoxifying enzymes and antioxidant proteins and thus has been considered a potential target for neuroprotection in stroke. The aim of the present study was to determine whether eriodictyol-7-O-glucoside (E7G), a novel Nrf2 activator, can protect against cerebral ischemic injury and to understand the role of the Nrf2/ARE pathway in neuroprotection. In primary cultured astrocytes, E7G increased the nuclear localization of Nrf2 and induced the expression of the Nrf2/ARE-dependent genes. Exposure of astrocytes to E7G provided protection against oxygen and glucose deprivation (OGD)-induced oxidative insult. The protective effect of E7G was abolished by RNA interference-mediated knockdown of Nrf2 expression. In vivo administration of E7G in a rat model of focal cerebral ischemia significantly reduced the amount of brain damage and ameliorated neurological deficits. These data demonstrate that activation of Nrf2/ARE signaling by E7G is directly associated with its neuroprotection against oxidative stress-induced ischemic injury and suggest that targeting the Nrf2/ARE pathway may be a promising approach for therapeutic intervention in stroke. - Highlights: • E7G activates Nrf2 in astrocytes. • E7G stimulates expression of Nrf2-mediated cytoprotective proteins in astrocytes. • E7G protects astrocytes against OGD-induced cell death and apoptosis. • The neuroprotective effect of E7G involves the Nrf2/ARE pathway. • E7G protects rats against cerebral ischemic injury.

  5. Threshold electron attachment and electron impact ionization involving oxygen dimers

    NASA Astrophysics Data System (ADS)

    Kreil, J.; Ruf, M.-W.; Hotop, H.; Ettischer, I.; Buck, U.

    1998-12-01

    Using two different crossed-beams machines we have carried out the first quantitative study of threshold electron attachment and electron impact-induced ionization and fragmentation involving oxygen dimers (O 2) 2. In the electron attachment experiment we study electron transfer from state-selected Ar **(20d) Rydberg atoms to O 2 molecules and dimers in a skimmed supersonic beam at variable nozzle temperatures ( T0) and stagnation pressures ( p0). The relative dimer density is determined through measurements of Penning ionization by metastable Ne *(3s 3P2,0) atoms and used to estimate the absolute cross-section for O 2- formation in collisions of Ar **(20d) Rydberg atoms with O 2 dimers to be nearly 10 -17 m 2, almost four orders of magnitude larger than that for O 2- formation in collisions of Ar **(20d) Rydberg atoms with O 2 monomers. The fragmentation of the oxygen cluster beam is quantitatively characterized by the transverse helium beam scattering method which allows us to spatially separate different clusters. It is shown that in 70 eV electron impact of (O 2) 2 only 3.6(4)% of the dimers are detected as dimer ions (O 2) 2+. In additional experiments involving SF 6 clusters we show that SF 6 dimers fragment nearly completely upon 70 eV electron impact, yielding SF 5+ ions (probability for (SF 6)·SF 5+ production at most 0.3%).

  6. Fibulin 5 Forms a Compact Dimer in Physiological Solutions*

    PubMed Central

    Jones, Richard P. O.; Wang, Ming-Chuan; Jowitt, Thomas A.; Ridley, Caroline; Mellody, Kieran T.; Howard, Marjorie; Wang, Tao; Bishop, Paul N.; Lotery, Andrew J.; Kielty, Cay M.; Baldock, Clair; Trump, Dorothy

    2009-01-01

    Fibulin 5 is a 52-kDa calcium-binding epidermal growth factor (cbEGF)-rich extracellular matrix protein that is essential for the formation of elastic tissues. Missense mutations in fibulin 5 cause the elastin disorder cutis laxa and have been associated with age-related macular degeneration, a leading cause of blindness. We investigated the structure, hydrodynamics, and oligomerization of fibulin 5 using small angle x-ray scattering, EM, light scattering, circular dichroism, and sedimentation. Compact structures for the monomer were determined by small angle x-ray scattering and EM, and are supported by close agreement between the theoretical sedimentation of the structures and the experimental sedimentation of the monomer in solution. EM showed that monomers associate around a central cavity to form a dimer. Light scattering and equilibrium sedimentation demonstrated that the equilibrium between the monomer and the dimer is dependent upon NaCl and Ca2+ concentrations and that the dimer is dominant under physiological conditions. The dimerization of fragments containing just the cbEGF domains suggests that intermolecular interactions between cbEGFs cause dimerization of fibulin 5. It is possible that fibulin 5 functions as a dimer during elastinogenesis or that dimerization may provide a method for limiting interactions with binding partners such as tropoelastin. PMID:19617354

  7. An Alternative Mechanism for the Dimerization of Formic Acid

    SciTech Connect

    Brinkman, Nicole R.; Tschumper, Gregory; Yan, Ge; Schaefer, Henry F.

    2003-11-01

    Gas-phase formic acid exists primarily as a cyclic dimer. The mechanism of dimerization has been traditionally considered to be a synchronous process; however, recent experimental findings suggest a possible alternative mechanism by which two formic acid monomers proceed through an acyclic dimer to the cyclic dimer in a stepwise process. To investigate this newly proposed process of dimerization in formic acid, density functional theory and second-order Moeller-Plesset perturbation theory (MP2) have been used to optimize cis and trans monomers of formic acid, the acyclic and cyclic dimers, and the acyclic and cyclic transition states between minima. Single-point energies of the trans monomer, dimer minima, and transition states at the MP2/TZ2P+diff optimized geometries were computed at the coupled-cluster level of theory including singles and doubles with perturbatively applied triple excitations [CCSD(T)] with an aug-cc-pVTZ basis set to obtain an accurate determination of energy barriers and dissociation energies. A counterpoise correction was performed to determine an estimate of the basis set superposition error in computing relative energies. The explicitly correlated MP2 method of Kutzelnigg and Klopper (MP2-R12) was used to provide an independent means for obtaining the MP2 one-particle limit. The cyclic minimum is predicted to be 6.3 kcal/mol more stable than the acyclic minimum, and the barrier to double proton transfer is 7.1 kcal/mol.

  8. Slow assembly and disassembly of lambda Cro repressor dimers.

    PubMed

    Jia, Haifeng; Satumba, W John; Bidwell, Gene L; Mossing, Michael C

    2005-07-29

    Dimers of Cro are required to recognize operator DNA and repress transcription, but dimerization is weak compared to DNA binding. Fluorophore-conjugated, single-cysteine variants of Cro have been used to investigate the equilibria and kinetics of dimer assembly. Equilibrium distributions of mixed dimers, monitored by fluorescence resonance energy transfer (FRET), confirm that labeled variants have equilibrium dimer dissociation constants in the micromolar concentration range. Subunit exchange experiments yield first order rate constants for dimer dissociation that range from 0.02 s(-1) to 0.04 s(-1). Association rate constants calculated from the ratios of dissociation equilibrium and rate constants range from 0.7x10(4) M(-1) s(-1) to 3x10(4) M(-1) s(-1), depending on the site of the fluorescent label. At nanomolar concentrations of subunits, assembly can be driven by addition of DNA. The bimolecular association rate constants measured under these conditions are not dramatically enhanced, ranging from 7x10(4) M(-1) s(-1) to 9x10(4) M(-1) s(-1). The association rate is second order in protein but independent of DNA concentration between 10 nM and 200 nM. The association of subunits under native conditions is more than four orders of magnitude slower than the fast assembly phase measured previously in refolding experiments, and is unaffected by peptidyl-prolyl isomerases. Stabilization of the folded structure of the protein by residue substitution in Cro F58W or reduced temperature increases the ratio of dimers to monomers and decreases the rate of subunit exchange. These data suggest that native monomers have compact structures with substantial barriers to unfolding and that unfolded or partially folded monomers are the preferred substrates for dimer assembly. Cro binding in vivo may be under kinetic rather than thermodynamic control. The slow assembly of Cro dimers demonstrated here provides a new perspective on the lysis/lysogeny switch of bacteriophage lambda.

  9. Plaquette order in a dimerized frustrated spin ladder

    NASA Astrophysics Data System (ADS)

    Shlagman, Ofer; Shimshoni, Efrat

    2014-11-01

    We study the effect of dimerization (due to, e.g., spin-Peierls instability) on the phase diagram of a frustrated antiferromagnetic spin-1/2 ladder, with weak transverse and diagonal rung coupling. Our analysis focuses on a one-dimensional version of the model (i.e., a single two-leg ladder) where we consider two forms of dimerization on the legs: columnar dimers (CDs) and staggered dimers (SDs). We examine in particular the regime of parameters (corresponding to an intermediate X X Z anisotropy) in which the leg dimerization and the rung coupling terms are equally relevant. In both the CD and SD cases, we find that the effective field theory describing the system is a self-dual sine-Gordon model, which favors ordering and the opening of a gap to excitations. The order parameter, which reflects the interplay between the leg and rung dimerization interactions, represents a crystal of 4-spin plaquettes on which longitudinal and transverse dimers are in a coherent superposition. Depending on the leg dimerization mode, these plaquettes are closed or open, however both types spontaneously break reflection symmetry across the ladder. The closed plaquettes are stable, while the open plaquette order is relatively fragile and the corresponding gap may be tuned to zero under extreme conditions. We further find that a first-order transition occurs from the plaquette order to a valence bond crystal (VBC) of dimers on the legs. This suggests that in a higher-dimensional version of this system, this variety of distinct VBC states with comparable energies leads to the formation of domains. Effectively one-dimensional gapless spinon modes on domain boundaries may account for the experimental observation of spin-liquid behavior in a physical realization of the model.

  10. Scattering properties of weakly-bound dimers of Fermi atoms

    NASA Astrophysics Data System (ADS)

    Petrov, Dmitry

    2005-03-01

    We discuss the behavior of weakly bound bosonic dimers formed in a two-component Fermi gas with a large positive scattering length for the interspecies interaction. We present a theoretical approach for solving a few-body scattering problem and describe the physics of dimer-dimer elastic and inelastic scattering. We explain why these diatomic molecules, while in the highest ro-vibrational level, are characterized by remarkable collisional stability. Co-authors are Christophe Salomon, LKB, Ecole Normale Superieure, Paris, France; Georgy Shlyapnikov, LPTMS, University of South Paris, Orsay, France.

  11. Modelization of surface diffusion of a molecular dimer.

    PubMed

    Romero, A H; Lacasta, A M; Sancho, J M

    2004-05-01

    A simple model for a dimer molecular diffusion on a crystalline surface, as a function of temperature, is presented. The dimer is formed by two particles coupled by a quadratic potential. The dimer diffusion is modeled by an overdamped Langevin equation in the presence of a two-dimensional periodic potential. Numerical simulation's results exhibit some dynamical properties observed, for example, in Si2 diffusion on a silicon [100] surface. They can be used to predict the value of the effective friction parameter. Comparison between our model and experimental measurements is presented.

  12. Electric and magnetic hotspots in dielectric nanowire dimers

    NASA Astrophysics Data System (ADS)

    Mirzaei, Ali; Miroshnichenko, Andrey E.

    2015-03-01

    We study the formation of the electric and magnetic near-field hotspots in dielectric cylindrical dimers. We compare dielectric and metallic dimers by using experimental data for all materials and consider both TM and TE polarizations of light. We demonstrate that dielectric dimers allow us to simultaneously achieve pure magnetic and electric near-field hotspots for both polarizations in contrast to plasmonic structures. This offers new approaches for near-field engineering such as sensing, control of spontaneous emission, and enhanced Raman scattering.

  13. Time resolved structural dynamics of butadiyne-linked porphyrin dimers

    PubMed Central

    Camargo, Franco V. A.; Hall, Christopher R.; Anderson, Harry L.; Meech, Stephen R.; Heisler, Ismael A.

    2016-01-01

    In this work, the timescales and mechanisms associated with the structural dynamics of butadiyne-linked porphyrin dimers are investigated through time resolved narrowband pump/broadband probe transient absorption spectroscopy. Our results confirm previous findings that the broadening is partly due to a distribution of structures with different (dihedral) angular conformations. Comparison of measurements with excitations on the red and blue sides of the Q-band unravel the ground and excited state conformational re-equilibration timescales. Further comparison to a planarized dimer, through the addition of a ligand, provides conclusive evidence for the twisting motion performed by the porphyrin dimer in solution. PMID:26798839

  14. Adsorption of silver dimer on graphene - A DFT study

    SciTech Connect

    Kaur, Gagandeep; Gupta, Shuchi; Rani, Pooja; Dharamvir, Keya

    2014-04-24

    We performed a systematic density functional theory (DFT) study of the adsorption of silver dimer (Ag{sub 2}) on graphene using SIESTA (Spanish Initiative for Electronic Simulations with Thousands of Atoms) package, in the generalized gradient approximation (GGA). The adsorption energy, geometry, and charge transfer of Ag2-graphene system are calculated. The minimum energy configuration for a silver dimer is parallel to the graphene sheet with its two atoms directly above the centre of carbon-carbon bond. The negligible charge transfer between the dimer and the surface is also indicative of a weak bond. The methodology demonstrated in this paper may be applied to larger silver clusters on graphene sheet.

  15. Monofunctionalization and dimerization of nanoparticles using coordination chemistry.

    PubMed

    Dewi, Melissa R; Gschneidtner, Tina A; Elmas, Sait; Ranford, Michael; Moth-Poulsen, Kasper; Nann, Thomas

    2015-02-24

    This paper describes a strategy for controlled nanoparticle dimerization by using a solid support approach. Two types of nanoparticles have been linked by using a 5-([2,2':6',2″-terpyridine]-4'-yloxy)pentan-1-amine (terpy-amine) iron complex. The strategy includes two major steps: first, the monofunctionalization of individual nanoparticles with terpy-amine ligand molecules on a solid support, followed by release of monofunctionalized particles and subsequent dimerization. The versatility of the approach was demonstrated by dimerizing two different types of nanoparticles: spherical gold and cube-shaped iron oxide nanoparticles.

  16. [Dichotomizing method applied to calculating equilibrium constant of dimerization system].

    PubMed

    Cheng, Guo-zhong; Ye, Zhi-xiang

    2002-06-01

    The arbitrary trivariate algebraic equations are formed based on the combination principle. The univariata algebraic equation of equilibrium constant kappa for dimerization system is obtained through a series of algebraic transformation, and it depends on the properties of monotonic functions whether the equation is solvable or not. If the equation is solvable, equilibrium constant of dimerization system is obtained by dichotomy and its final equilibrium constant of dimerization system is determined according to the principle of error of fitting. The equilibrium constants of trisulfophthalocyanine and biosulfophthalocyanine obtained with this method are 47,973.4 and 30,271.8 respectively. The results are much better than those reported previously.

  17. Human white blood cells contain cyclobutyl pyrimidine dimer photolyase

    SciTech Connect

    Sutherland, B.M.; Bennett, P.V.

    1995-10-10

    Although enzymatic photoreactivation of cyclobutyl pyrimidine dimers in DNA is present in almost all organisms, its presence in placental mammals is controversial. We tested human white blood cells for photolyase by using three defined DNAs (suprecoiled pET-2, nonsupercoiled bacteriphage {lambda}, and a defined-sequence 287-bp oligonucleotide), two dimer-specific endonucleases (T4 endonuclease V and UV endonuclease from Micrococcus luteus), and three assay methods. We show that human white blood cells contain photolyase that can photorepair pyrimidine dimers in defined supercoiled and linear DNAs and in a 287-bp oligonucleotide and that human photolyase is active on genomic DNA in intact human cells. 44 refs., 3 figs.

  18. Ballistic transport in one-dimensional random dimer photonic crystals

    NASA Astrophysics Data System (ADS)

    Cherid, Samira; Bentata, Samir; Zitouni, Ali; Djelti, Radouan; Aziz, Zoubir

    2014-04-01

    Using the transfer-matrix technique and the Kronig Penney model, we numerically and analytically investigate the effect of short-range correlated disorder in Random Dimer Model (RDM) on transmission properties of the light in one dimensional photonic crystals made of three different materials. Such systems consist of two different structures randomly distributed along the growth direction, with the additional constraint that one kind of these layers always appear in pairs. It is shown that the one dimensional random dimer photonic crystals support two types of extended modes. By shifting of the dimer resonance toward the host fundamental stationary resonance state, we demonstrate the existence of the ballistic response in these systems.

  19. Specificity of binding of beta-glucoside activators of ryegrass (1-->3)-beta-glucan synthase and the synthesis of some potential photoaffinity activators.

    PubMed Central

    Ng, K; Johnson, E; Stone, B A

    1996-01-01

    Structure-activity relationships among glycoside activators of ryegrass (Lolium multiflorum) (1-->3)-beta-glucan synthase were investigated using a number of natural and synthetic glycosides, including some carrying photoaffinity functions. There is an absolute requirement for a beta-D-glycosyl moiety in the activator, both S- and N-glucosides are active, and the position of the glucosidic linkage in beta-glucose disaccharides has a significant effect on the affinity of binding. However, the binding requirement does not extend beyond a single beta-D-glucosyl residue, and beta-D-oligoglucosides are less effective than disaccharides. The nature of the aglycon has a major influence on the binding affinity. Hydrophobic aglycons lower the concentration required for half-maximal stimulation of the enzyme obtained from an Eadie-Hofstee plot of kinetic data (Ka) for activation, but charge aglycons increase Ka. Relative to methyl-beta-D-glucoside and cellobiose (Ka 1.1 mM), the most potent compounds tested were N-[4-(benzoyl)benzoyl]-beta-D-glucosylamine and 2'-[4-azidosalicylamino]ethyl-1-thio-beta-D-glucoside with K(a)s of approximately 30 microM. The latter also was tested for its potential to specifically label the beta-glucoside-binding site on the synthase, but under the conditions used the binding was found to be nonspecific. PMID:8756503

  20. Targeting RNA by Small Molecules: Comparative Structural and Thermodynamic Aspects of Aristololactam-β-D-glucoside and Daunomycin Binding to tRNAphe

    PubMed Central

    Das, Abhi; Bhadra, Kakali; Suresh Kumar, Gopinatha

    2011-01-01

    Background Interaction of aristololactam-β-D-glucoside and daunomycin with tRNAphe was investigated using various biophysical techniques. Methodology/Principal Findings Absorption and fluorescence studies revealed that both the compounds bind tRNAphe non-cooperatively. The binding of daunomycin was about one order of magnitude higher than that of aristololactam-β-D-glucoside. Stronger binding of the former was also inferred from fluorescence quenching data, quantum efficiency values and circular dichroic results. Results from isothermal titration calorimetry experiments suggested that the binding of both compounds was predominantly entropy driven with a smaller but favorable enthalpy term that increased with temperature. A large favorable electrostatic contribution to the binding of daunomycin to tRNAphe was revealed from salt dependence data and the dissection of the free energy values. The electrostatic component to the free energy change for aristololactam-β-D-glucoside-tRNAphe interaction was smaller than that of daunomycin. This was also inferred from the slope of log K versus [Na+] plots. Both compounds enhanced the thermal stability of tRNAphe. The small heat capacity changes of -47 and -99 cal/mol K, respectively, observed for aristololactam-β-D-glucoside and daunomycin, and the observed enthalpy-entropy compensation phenomenon confirmed the involvement of multiple weak noncovalent interactions. Molecular aspects of the interaction have been revealed. Conclusions/Significance This study presents the structural and eneregetic aspects of the binding of aristololactam-β-D-glucoside and daunomycin to tRNAphe. PMID:21858023

  1. Genomic clustering of cyanogenic glucoside biosynthetic genes aids their identification in Lotus japonicus and suggests the repeated evolution of this chemical defence pathway.

    PubMed

    Takos, Adam M; Knudsen, Camilla; Lai, Daniela; Kannangara, Rubini; Mikkelsen, Lisbeth; Motawia, Mohammed S; Olsen, Carl E; Sato, Shusei; Tabata, Satoshi; Jørgensen, Kirsten; Møller, Birger L; Rook, Fred

    2011-10-01

    Cyanogenic glucosides are amino acid-derived defence compounds found in a large number of vascular plants. Their hydrolysis by specific β-glucosidases following tissue damage results in the release of hydrogen cyanide. The cyanogenesis deficient1 (cyd1) mutant of Lotus japonicus carries a partial deletion of the CYP79D3 gene, which encodes a cytochrome P450 enzyme that is responsible for the first step in cyanogenic glucoside biosynthesis. The genomic region surrounding CYP79D3 contains genes encoding the CYP736A2 protein and the UDP-glycosyltransferase UGT85K3. In combination with CYP79D3, these genes encode the enzymes that constitute the entire pathway for cyanogenic glucoside biosynthesis. The biosynthetic genes for cyanogenic glucoside biosynthesis are also co-localized in cassava (Manihot esculenta) and sorghum (Sorghum bicolor), but the three gene clusters show no other similarities. Although the individual enzymes encoded by the biosynthetic genes in these three plant species are related, they are not necessarily orthologous. The independent evolution of cyanogenic glucoside biosynthesis in several higher plant lineages by the repeated recruitment of members from similar gene families, such as the CYP79s, is a likely scenario.

  2. Ab initio calculations of nitramine dimers

    NASA Astrophysics Data System (ADS)

    Koh-Fallet, Sharon; Schweigert, Igor

    2015-06-01

    Elevated temperatures and pressures are typically thought to have opposing effects on the reaction channels of nitramine decomposition. These high temperatures promote reactions with loose transition structures (positive activation entropies and volumes), such as N-N bond homolysis. Elevated pressures promote reactions with tight transition structures (negative activation entropies and volumes), such as intramolecular and intermolecular H transfer. However, no quantitative data exists regarding the range of temperatures and pressures at which these effects become pronounced. We are pursuing ab initio calculations of the corresponding unimolecular and bimolecular transition structures with the objective of estimating the relevant thermochemical parameters and quantifying the effects of elevated temperature and pressures on the corresponding rate constants. Here, we present density functional theory and complete active space calculations of gas-phase molecular dimers of nitramines as an intermediate step toward modeling transition structures directly in the condensed phase. This work was supported by the Naval Research Laboratory via the American Society for Engineering and Education and by the Office of Naval Research, both directly and through the Naval Research Laboratory.

  3. Dimer packings with gaps and electrostatics

    PubMed Central

    Ciucu, Mihai

    2008-01-01

    Fisher and Stephenson conjectured in 1963 that the correlation function (defined by dimer packings) of two unit holes on the square lattice is rotationally invariant in the limit of large separation between the holes. We consider the same problem on the hexagonal lattice, extend it to an arbitrary finite collection of holes, and present an explicit conjectural answer. In recent work we managed to prove this conjecture in two fairly general cases. The quantity giving the answer can be regarded as the exponential of the negative of the two-dimensional electrostatic energy of a system of charges naturally associated with the holes. We further develop this analogy to electrostatics by presenting two different natural ways to define a field in our setup, and showing that both lead to the electric field, in the limit of large separations between the holes. For one of the fields, this is also stated as a limit shape theorem for random surfaces, with the continuum limit being a sum of helicoids. We conclude by explaining the relationship of our results to previous results in the physics literature on spin correlations in the Ising model.

  4. Assembly of Dimer-Based Photonic Crystals

    NASA Astrophysics Data System (ADS)

    Liddell Watson, Chekesha M.

    2011-03-01

    Recent advances in colloid synthesis to prepare monodisperse shape anisotropic particles provide the opportunity to address challenges related to structural diversity in ordered colloidal solids. In particular, computational simulations and mechanical models suggest that upon system densification nonspherical dimer colloids undergo disorder-order and order-order phase transitions to unconventional solid structures including, base-centered monoclinic crystals, degenerate aperiodic crystals, plastic crystal or rotator, etc. based on free energy minimization. The particle systems have notable analogy to molecular systems, where the shape of molecules and their packing density has been shown to critically influence structural phase behavior and lead to a rich variety of structures, both natural and synthetic. The materials engineering challenges have been in attaining sufficiently monodisperse (size uniformity) colloidal building blocks, as well as the lack of understanding and control of self-assembly processes for non-spherical colloids. This talk highlights our investigations of how particle shape programs the self-organization of colloidal structures. Methods including evaporation mediated assembly and confinement provide a platform to understand the formation of complex colloidal structures from non-spherical building blocks (silica-coated iron oxide, polystyrene, hollow silica shell). Optical property simulations for unconventional 2D and 3D structures with nonspherical particle bases will also be discussed.

  5. Smectic Phase Formed by DNA Dimers

    NASA Astrophysics Data System (ADS)

    Salamonczyk, Miroslaw; Gleeson, James; Jakli, Antal; Sprunt, Samuel; Dhont, Jan; Stiakakis, Emmanuel

    The rapidly expanding bio market is driving the development and characterization of new multifunctional materials. In particular, nucleic acids are under intense study for gene therapy, drug delivery and other bio-safe applications [1,2,3]. DNA is well-known to form a cholesteric nematic liquid crystal in its native form; however, much recent research has focused on self-assembly and mesomorphic behavior in concentrated solutions of short DNA helices [4]. Our work focuses on DNA dimers, consisting of 48 base-pair double-stranded helices connected by a 5 to 20 base flexible single strand, and suspended in a natural buffer. Depending on temperature, concentration and length of the flexible spacer, polarizing optical microscopy and small angle x-ray scattering reveal cholesteric nematic and, remarkably, smectic liquid crystalline phases. A model for smectic phase formation in this system will be presented. 1] J.-L. Lim et al., Int. J. of. Pharm. 490 (2015) 2652] D.-H. Kim et al., Nature Biotech. 23 (2005) 2223] K. Liu et al., Chem. Eur. J. 21 (2015) 48984] M. Nakata et al., Science 318 (2007) 1276 NSF DMR 1307674.

  6. Vibrations of the carbon dioxide dimer

    NASA Astrophysics Data System (ADS)

    Chen, Hua; Light, J. C.

    2000-03-01

    Fully coupled four-dimensional quantum-mechanical calculations are presented for intermolecular vibrational states of rigid carbon dioxide dimer for J=0. The Hamiltonian operator is given in collision coordinates. The Hamiltonian matrix elements are evaluated using symmetrized products of spherical harmonics for angles and a potential optimized discrete variable representation (PO-DVR) for the intermolecular distance. The lowest ten or so states of each symmetry are reported for the potential energy surface (PES) given by Bukowski et al. [J. Chem. Phys. 110, 3785 (1999)]. Due to symmetries, there is no interconversion tunneling splitting for the ground state. Our calculations show that there is no tunneling shift of the ground state within our computation precision (0.01 cm-1). Analysis of the wave functions shows that only the ground states of each symmetry are nearly harmonic. The van der Waals frequencies and symmetry adapted force constants are found and compared to available experimental values. Strong coupling between the stretching coordinates and the bending coordinates are found for vibrationally excited states. The interconversion tunneling shifts are discussed for the vibrationally excited states.

  7. Spin Dimers: from BEC to Luttinger liquids

    NASA Astrophysics Data System (ADS)

    Giamarchi, Thierry

    2011-03-01

    Localized spin systems, and in particular dimer systems, provide a fantastic laboratory to study the interplay between quantum effects and the interaction between excitations. Magnetic field and temperature allow an excellent control on the density of excitations and various very efficient probes such as neutrons and NMR are available. They can thus be used as ``quantum simulators'' to tackle with great success questions that one would normally search in itinerant interacting quantum systems. In particular they have provided excellent realizations of Bose-Einstein condensates [1,2]. This allowed not only to probe the properties of interacting bosons in a variety of dimensions but also to study in a controlled way additional effects such as disorder. If the dimensionality is reduced they also allow to test in a quantitative way Luttinger liquid physics [3,4,5]. I will discuss these various cases, and show that we have now good theoretical tools to make quantitative comparisons with the experiments. Finally, how to go from this low dimensional case where the spins behave essentially as fermions, to the higher dimensional case where they behave as (essentially free) bosons, is a very challenging, and experimentally relevant issue. This work was supported in part by the Swiss SNF under MaNEP and division II.

  8. Repressor Dimerization in the Zebrafish Somitogenesis Clock

    PubMed Central

    Cinquin, Olivier

    2007-01-01

    The oscillations of the somitogenesis clock are linked to the fundamental process of vertebrate embryo segmentation, yet little is known about their generation. In zebrafish, it has been proposed that Her proteins repress the transcription of their own mRNA. However, in its simplest form, this model is incompatible with the fact that morpholino knockdown of Her proteins can impair expression of their mRNA. Simple self-repression models also do not account for the spatiotemporal pattern of gene expression, with waves of gene expression shrinking as they propagate. Here we study computationally the networks generated by the wealth of dimerization possibilities amongst transcriptional repressors in the zebrafish somitogenesis clock. These networks can reproduce knockdown phenotypes, and strongly suggest the existence of a Her1–Her7 heterodimer, so far untested experimentally. The networks are the first reported to reproduce the spatiotemporal pattern of the zebrafish somitogenesis clock; they shed new light on the role of Her13.2, the only known link between the somitogenesis clock and positional information in the paraxial mesoderm. The networks can also account for perturbations of the clock by manipulation of FGF signaling. Achieving an understanding of the interplay between clock oscillations and positional information is a crucial first step in the investigation of the segmentation mechanism. PMID:17305423

  9. Comparison of nano and conventional liquid chromatographic methods for the separation of (+)-catechin-ethyl-malvidin-3-glucoside diastereoisomers.

    PubMed

    Kučera, Lukáš; Fanali, Salvatore; Aturki, Zeineb; Pospíšil, Tomáš; Bednář, Petr

    2016-01-08

    Nano-liquid chromatography and conventional HPLC were used for the separation of diastereomers of (+)-catechin-ethyl-malvidin-3-glucoside. Those bridged anthocyanin dyes were obtained by reaction of (+)-catechin with malvidin-3-glucoside in the presence of acetaldehyde. Both diastereomers were isolated with semipreparative chromatography and their structures were confirmed by nuclear magnetic resonance and mass spectrometry. In-laboratory prepared capillary columns packed with fully porous particles Chromosphere C18, dp=3μm, core-shell particles Kinetex C18, dp=2.6μm (100μm i.d.) and monolithic column Chromolith CapRod (100μm i.d.) were used for the separation of (+)-catechin, malvidin-3-glucoside and both diastereomers. Chromosphere C18 stationary phase provided the best chromatographic performance. Mobile phase containing water:acetonitrile (80:20) acidified with trifluoroacetic acid (0.1%, v/v/v) was used in an isocratic elution mode with a flow rate of 360nLmin(-1). Separation of studied compounds was achieved in less than 7min under optimized conditions. The nano-liquid chromatographic method and a conventional HPLC one using the same fully porous particles (Chromosphere C18, 3μm, 100mm×4.6mm) were compared providing higher separation efficiency with the first analytical method and similar selectivity. A better peak symmetry and higher resolution of the studied diastereomers was achieved by conventional chromatography. Nevertheless, nano-liquid chromatography appeared to be useful for the separation of complex anthocyanin dyes and can be utilized for their analysis in plant and food micro-samples. The developed method was used for analysis of red wine grape pomace. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Chronic Exposure to Dietary Sterol Glucosides is Neurotoxic to Motor Neurons and Induces an ALS-PDC Phenotype

    PubMed Central

    Tabata, R. C.; Wilson, J. M. B.; Ly, P.; Zwiegers, P.; Kwok, D.; Van Kampen, J. M.; Cashman, N.; Shaw, C. A.

    2008-01-01

    Epidemiological studies of the Guamanian variants of amyotrophic lateral sclerosis (ALS) and parkinsonism, amyotrophic lateral sclerosis-parkinsonism dementia complex (ALS-PDC), have shown a positive correlation between consumption of washed cycad seed flour and disease occurrence. Previous in vivo studies by our group have shown that the same seed flour induces ALS and PDC phenotypes in out bred adult male mice. In vitro studies using isolated cycad compounds have also demonstrated that several of these are neurotoxic, specifically, a number of water insoluble phytosterol glucosides of which β-sitosterol β-d-glucoside (BSSG) forms the largest fraction. BSSG is neurotoxic to motor neurons and other neuronal populations in culture. The present study shows that an in vitro hybrid motor neuron (NSC-34) culture treated with BSSG undergoes a dose-dependent cell loss. Surviving cells show increased expression of HSP70, decreased cytosolic heavy neurofilament expression, and have various morphological abnormalities. CD-1 mice fed mouse chow pellets containing BSSG for 15 weeks showed motor deficits and motor neuron loss in the lumbar and thoracic spinal cord, along with decreased glutamate transporter labelling, and increased glial fibrillary acid protein reactivity. Other pathological outcomes included increased caspase-3 labelling in the striatum and decreased tyrosine-hydroxylase labelling in the striatum and substantia nigra. C57BL/6 mice fed BSSG-treated pellets for 10 weeks exhibited progressive loss of motor neurons in the lumbar spinal cord that continued to worsen even after the BSSG exposure ended. These results provide further support implicating sterol glucosides as one potential causal factor in the motor neuron pathology previously associated with cycad consumption and ALS-PDC. PMID:18196479

  11. Effect of Multiple Dietary Supplement Containing Lutein, 
Astaxanthin, Cyanidin-3-Glucoside, and DHA on Accommodative Ability

    PubMed Central

    Kono, Keiko; Shimizu, Yoshiki; Takahashi, Satomi; Matsuoka, Sayuri; Yui, Kei

    2014-01-01

    Objective The study aimed to verify that ingestion of multiple dietary supplement containing lutein, astaxanthin, cyanidin-3-glucoside and docosahexaenoic acid (DHA) would improve accommodative ability of aged and older subjects who were aware of eye strain on a daily basis. Methods A randomized double-blind placebo-controlled parallel group comparison study was conducted for 48 participants aged 45 to 64 years who complained of eye strain. The subjects took multiple dietary supplement containing 10 mg of lutein, 20 mg of bilberry extract and 26.5 mg of black soybean hull extract (a total of 2.3 mg of cyanidin-3-glucoside in both extracts), 4 mg of astaxanthin, and 50 mg of DHA (test supplement) or placebo for four consecutive weeks. Near-point accommodation (NPA) and subjective symptoms were evaluated both before and after four weeks’ intake. Results The variation of the NPA of both eyes from baseline to 4 weeks’ post-intake in the test supplement group was significantly higher than in the placebo group (1.321±0.394 diopter (D) in the test supplement group and 0.108±0.336 D in the placebo group, p=0.023). The multiple dietary supplement group showed improvement in the NPA. Regarding subjective symptoms, significant improvement of “stiff shoulders or neck” and “blurred vision” was also found in the test supplement group compared to the placebo group (p<0.05). There were no safety concerns in this study. Conclusion This study shows that multiple dietary supplement containing lutein, astaxanthin, cyanidin-3-glucoside, and DHA has effect to improve accommodative ability and subjective symptoms related to eye fatigue.

  12. A study of transglucosylation kinetic in an enzymatic synthesis of benzyl alcohol glucoside by α-glucosidase from S. cerevisiae

    NASA Astrophysics Data System (ADS)

    Pavlović, M.; Dimitrijević, A.; Trbojević, J.; Milosavić, N.; Gavrović-Jankulović, M.; Bezbradica, D.; Veličković, D.

    2013-12-01

    α-1,4-Glucosidase from Saccharomyces cerevisiae is an enzyme which is widely used in synthesis of different drugs. Glucosidase inhibitors are studied as potential drugs for prevention of HIV and diabetes. For understanding of these processes it is very important to have insights in the transglucosylation activity of this enzyme. In this paper the kinetics of transglucosylation reaction catalyzed by this enzyme in the synthesis of benzyl alcohol glucoside was studied and all relevant kinetic constants for this system are found. It was shown one additional property of transglycosylation reactions catalyzed by glycosidases—inhibition by both, glucose acceptor and glucose donor, and mechanisms for these inhibitions were proposed.

  13. Sodium dimers on the surface of liquid {sup 4}He

    SciTech Connect

    Ancilotto, F.; DeToffol, G.; Toigo, F.

    1995-12-01

    We have studied the structure of a sodium dimer interacting with liquid {sup 4}He. We calculated the equilibrium configuration and binding energy of a Na{sub 2} molecule solvated in a bulk liquid {sup 4}He ``bubble`` and near the liquid-vapor interface ``dimple`` by using a density-functional approach. We find that the solvated molecule is a metastable state, while the the lowest energy bound state occurs when the molecule lies flat on the surface of the liquid. The binding energy for the ``erect`` dimer is only {similar_to}1 K higher than the flat dimer, with no potential energy barrier between the two orientations, implying relatively free rotations of the molecule on the surface. The small effects of the liquid environment on the vibrational properties of the dimer are investigated.

  14. Metallothionein dimers studied by nano-spray mass spectrometry.

    PubMed

    Hathout, Yetrib; Reynolds, Kristy J; Szilagyi, Zoltan; Fenselau, Catherine

    2002-01-15

    Both transient and stable dimers of metallothionein have been characterized, based on earlier studies using NMR, circular dichroism and size-exclusion chromatography. Here additional characterization is provided by nanospray mass spectrometry. Rapid redistribution of metal ions between monomeric Cd7- and Zn7-metallothionein 2a is monitored by nanospray. An experiment in which theses two forms of the monomeric protein are separated by a dialysis membrane, which will pass metal ions but not proteins, confirms that a transient dimer must form for metal ions to be redistributed. On the other hand, size-exclusion chromatography of reconstituted Zn7- or Cd7-metallothionein revealed the presence of monomeric and dimeric species. These dimers do not equilibrate readily to form monomers and they are shown to be covalent.

  15. [Antioxidant and antibacterial activities of dimeric phenol compounds].

    PubMed

    Ogata, Masahiro

    2008-08-01

    We studied the antioxidant and antibacterial activities of monomeric and dimeric phenol compounds. Dimeric compounds had higher antioxidant activities than monomeric compounds. Electron spin resonance spin-trapping experiments showed that phenol compounds with an allyl substituent on their aromatic rings directly scavenged superoxide, and that only eugenol trapped hydroxyl radicals. We developed a generation system of the hydroxyl radical without using any metals by adding L-DOPA and DMPO to PBS or MiliQ water in vitro. We found that eugenol trapped hydroxyl radicals directly and is metabolized to a dimer. On the other hand, dipropofol, a dimer of propofol, has strong antibacterial activity against Gram-positive bacteria. However, it lacks solubility in water and this property is assumed to limit its efficacy. We tried to improve the solubility and found a new solubilization method of dipropofol in water with the addition of a monosaccharide or ascorbic acid.

  16. Diffusion of Al dimers on the surface of Mg clusters

    NASA Astrophysics Data System (ADS)

    Dai, Xiongying; Yang, Jianyu; Hu, Wangyu; Liu, Yanhui

    2017-06-01

    The surface diffusion of Al dimmers on Mg clusters with hexahedral structure was studied using the combination of quenched molecular dynamics and the embedded atom method. The system energy barriers of typical minimum energy diffusion paths for Al dimers on the Mg clusters were calculated using the Nudged Elastic Band method. In our study range (153-4061 atoms), the binding energies on the (0001) facets and the (1{\\overline 1 }01) facets differed, the binding energy on the former was lower than that on the latter. Moreover, cluster size only slightly influenced the binding energy values. Two possible diffusion paths were studied. Results showed that the diffusion of the dimer on the (0001) facet easily occurred at low temperatures. Furthermore, the interaction between the two atoms of the dimer facilitated the dimer crossing of the step edge between the (1{\\overline 1 }01) facets by hopping mechanism.

  17. UV spectra of benzene isotopomers and dimers in helium nanodroplets

    NASA Astrophysics Data System (ADS)

    Schmied, Roman; ćarçabal, Pierre; Dokter, Adriaan M.; Lonij, Vincent P. A.; Lehmann, Kevin K.; Scoles, Giacinto

    2004-08-01

    We report spectra of various benzene isotopomers and their dimers in helium nanodroplets in the region of the first Herzberg-Teller allowed vibronic transition 601 1B2u←1A1g (the A00 transition) at ˜260 nm. Excitation spectra have been recorded using both beam depletion detection and laser-induced fluorescence. Unlike for many larger aromatic molecules, the monomer spectra consist of a single "zero-phonon" line, blueshifted by ˜30 cm-1 from the gas phase position. Rotational band simulations show that the moments of inertia of C6H6 in the nanodroplets are at least six-times larger than in the gas phase. The dimer spectra present the same vibronic fine structure (though modestly compressed) as previously observed in the gas phase. The fluorescence lifetime and quantum yield of the dimer are found to be equal to those of the monomer, implying substantial inhibition of excimer formation in the dimer in helium.

  18. DLTS study of the oxygen dimer formation kinetics in silicon

    NASA Astrophysics Data System (ADS)

    Yarykin, Nikolai; Weber, Jörg

    2009-12-01

    The introduction rates of radiation defects, in particular the X- and M-centers for which the oxygen dimer is a precursor, are investigated as a function of duration of the pre-irradiation heat treatment at 480∘ C in Czochralski-grown silicon both of n- and p-types. The characteristic annealing time to grow the X-center concentration in the n-type crystal is found to be about 1 h in accordance with the model which implies no significant barrier for the dimer formation. The M-center concentration in the p-type crystal is found to be nearly independent of duration of the pre-irradiation annealing after a few minutes transient period. This behavior is ascribed to the stabilization of dimer concentration due to an effective dimer trapping in these samples.

  19. Pyrimidine dimer formation by UVA radiation: Implications for photoreactivation

    SciTech Connect

    Sutherland, B.M.; Hacham, H.; Sutherland, J.C. ); Gange, R.W. . Dept. of Dermatology)

    1991-01-01

    The duality of biological and biochemical effects mediated by UVA radiation complicates evaluation of its biological role. On the one hand, UVA can drive photoreactivation and prevent inactivation of a UV-irradiated organism; on the other hand, UVA clearly kills cells. We have investigated the ability of UVA to induce pyrimidine dimers in human skin in situ. Results of these studies indicate that UVA induces easily quantifiable levels of pyrimidine dimers in the DNA of human skin exposed in situ; and significant levels of dimers are induced in skin exposed to biologically relevant UVA doses (0--1 minimal erythemal dose (MED)). Also, UVA doses appropriate for photorepair may induce sufficient dimer frequencies to mask photoreactivation in biological systems, including human skin. Therefore, careful design of photoreactivation experiments is essential. The UV lamp used must not reverse or convert photodamage, nor induce additional lesions in the DNA. 29 refs., 4 figs., 2 tabs.

  20. Non-stripe charge order in dimerized organic conductors

    NASA Astrophysics Data System (ADS)

    Mori, Takehiko

    2016-06-01

    This paper demonstrates charge order is important in dimerized β - and κ -phase organic conductors similar to the uniform θ - and α -phase conductors. Here the magnitude of the dimerization represents the deviation from the ideal triangular lattice in analogy with the anisotropy in the θ phase. Since the ratio of the intradimer transfer integral to the interdimer transfer integral is as large as ˜2.6 , these dimerized phases lead to a dimer Mott insulator, whereas the Coulomb repulsion is closer to the triangular lattice because the ratio of the intradimer Coulomb repulsion to the interdimer Coulomb repulsion is comparatively small (˜1.7 ). Accordingly, in the static-limit calculation, non-stripe charge order with threefold periodicity appears between the uniform and the stripe phases, and the analogy with the θ phase suggests the first-order nature of the metal-insulator transition.

  1. Dimer model for Tau proteins bound in microtubule bundles

    NASA Astrophysics Data System (ADS)

    Hall, Natalie; Kluber, Alexander; Hayre, N. Robert; Singh, Rajiv; Cox, Daniel

    2013-03-01

    The microtubule associated protein tau is important in nucleating and maintaining microtubule spacing and structure in neuronal axons. Modification of tau is implicated as a later stage process in Alzheimer's disease, but little is known about the structure of tau in microtubule bundles. We present preliminary work on a proposed model for tau dimers in microtubule bundles (dimers are the minimal units since there is one microtubule binding domain per tau). First, a model of tau monomer was created and its characteristics explored using implicit solvent molecular dynamics simulation. Multiple simulations yield a partially collapsed form with separate positively/negatively charged clumps, but which are a factor of two smaller than required by observed microtubule spacing. We argue that this will elongate in dimer form to lower electrostatic energy at a cost of entropic ``spring'' energy. We will present preliminary results on steered molecular dynamics runs on tau dimers to estimate the actual force constant. Supported by US NSF Grant DMR 1207624.

  2. Universal dimer–dimer scattering in lattice effective field theory

    DOE PAGES

    Elhatisari, Serdar; Katterjohn, Kris; Lee, Dean; ...

    2017-03-14

    We consider two-component fermions with short-range interactions and large scattering length. This system has universal properties that are realized in several different fields of physics. In the limit of large fermion–fermion scattering length aff and zero-range interaction, all properties of the system scale proportionally with aff. For the case with shallow bound dimers, we calculate the dimer–dimer scattering phase shifts using lattice effective field theory. We extract the universal dimer–dimer scattering length add/aff=0.618(30) and effective range rdd/aff=-0.431(48). This result for the effective range is the first calculation with quantified and controlled systematic errors. We also benchmark our methods by computingmore » the fermion–dimer scattering parameters and testing some predictions of conformal scaling of irrelevant operators near the unitarity limit.« less

  3. How to use D-dimer in acute cardiovascular care.

    PubMed

    Giannitsis, Evangelos; Mair, Johannes; Christersson, Christina; Siegbahn, Agneta; Huber, Kurt; Jaffe, Allan S; Peacock, W Frank; Plebani, Mario; Thygesen, Kristian; Möckel, Martin; Mueller, Christian; Lindahl, Bertil

    2017-02-01

    D-dimer testing is important to aid in the exclusion of venous thromboembolic events (VTEs), including deep venous thrombosis and pulmonary embolism, and it may be used to evaluate suspected aortic dissection. D-dimer is produced upon activation of the coagulation system with the generation and subsequent degradation of cross-linked fibrin by plasmin. Many different assays for D-dimer testing are currently used in routine care. However, these tests are neither standardized nor harmonized. Consequently, only clinically validated assays and assay specific decision limits should be used for routine testing. For the exclusion of pulmonary embolism/deep vein thrombosis, age-adjusted cut-offs are recommend. Clinicians must be aware of the validated use of their hospital's D-dimer assay to avoid inappropriate use of this biomarker in routine care.

  4. The role of dimers in evaporation of small argon clusters.

    PubMed

    Napari, Ismo; Vehkamaki, Hanna

    2004-07-08

    Evaporation of small Lennard-Jones argon clusters has been studied using molecular dynamic simulations. An extensive library of clusters with 4, 5, 6, 11, and 21 atoms has been obtained from an earlier study. Analysis of the evaporation properties of the clusters indicate, that the fraction of dimer evaporations of all evaporation events increases with the total energy of the cluster. The fraction of evaporated dimers from clusters with a constant lifetime is independent of the cluster size for short-lived clusters and increases with cluster size for long-lived clusters. Only a few percent of the clusters which are long lived enough to participate in vapor-liquid nucleation decay by emitting dimers. The mean cluster lifetime as a function of total energy shows the same exponentially decreasing trend for monomer and dimer evaporation channels. The fraction of trimer evaporations is found to be vanishingly small.

  5. Dynamics of Azobenzene Dimer Photoisomerization: Electronic and Steric Effects.

    PubMed

    Titov, Evgenii; Granucci, Giovanni; Götze, Jan Philipp; Persico, Maurizio; Saalfrank, Peter

    2016-09-15

    While azobenzenes readily photoswitch in solution, their photoisomerization in densely packed self-assembled monolayers (SAMs) can be suppressed. Reasons for this can be steric hindrance and/or electronic quenching, e.g., by exciton coupling. We address these possibilities by means of nonadiabatic molecular dynamics with trajectory surface hopping calculations, investigating the trans → cis isomerization of azobenzene after excitation into the ππ* absorption band. We consider a free monomer, an isolated dimer and a dimer embedded in a SAM-like environment of additional azobenzene molecules, imitating in this way the gradual transition from an unconstrained over an electronically coupled to an electronically coupled and sterically hindered, molecular switch. Our simulations reveal that in comparison to the single molecule the quantum yield of the trans → cis photoisomerization is similar for the isolated dimer, but greatly reduced in the sterically constrained situation. Other implications of dimerization and steric constraints are also discussed.

  6. Superconductivity in the liquid-dimer valence-bond state

    SciTech Connect

    Ioffe, L.B.; Larkin, A.I. )

    1989-10-01

    Introducing an unambiguous prescription which converts singlet dimers into quasidipoles, we describe the low-energy excitations in the liquid-dimer state as fluctuations of the average dipole moment. The exchange of these fluctuations leads to a long-range interaction between holes in this state. This interaction favors the two-particle Bose condensate and destroys the order parameter of the one-particle Bose condensate even at zero temperature.

  7. Absorption cross sections of the ClO dimer

    NASA Technical Reports Server (NTRS)

    Huder, K. J.; DeMore, W. B.

    1995-01-01

    The absorption cross sections of the ClO dimer, ClOOCl, are important to the photochemistry of ozone depletion in the Antarctic. In this work, new measurements were made of the dimer cross sections at 195 K. the results yield somewhat lower values in the long wavelength region, compared to those currently recommended in the NASA data evaluation (JPL 94-26). The corresponding solar photodissociation rates in the Antarctic are reduced by about 40%.

  8. Design and Preparation of Nanoparticle Dimers for SERS Detection

    DTIC Science & Technology

    2012-09-10

    aptamers (aptatags) or antibodies (antitags) as the recognition elements. Preparation of 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 09-10...resulting dimeric structures incorporate aptamers (aptatags) or antibodies (antitags) as the recognition elements. Preparation of suitable sensing...signal   enhancement   is   at   its   maximum.     The   resulting   dimeric   structures   incorporate   aptamers

  9. Modulation of proton pumping across proteoliposome membranes reconstituted with tonoplast H(+)-ATPase from cultured rice (Oryza sativa L. var. Boro) cells by acyl steryl glucoside and steryl glucoside.

    PubMed

    Yamaguchi, Mineo; Kasamo, Kunihiro

    2002-07-01

    Tonoplast H(+)-ATPase purified from cultured rice cells (Oryza sativa L. var. Boro) was reconstituted into asolectin liposomes containing steryl glucoside (SG) or acyl steryl glucoside (ASG), and the effects of SG and ASG on proton pumping, ATP-hydrolysis activity and proton permeability of the proteoliposome membranes were investigated. In the proteoliposomes containing 10 mol% SG, proton pumping and ATP-hydrolysis activity were increased to around 140% of those in SG-free proteoliposomes. In the proteoliposomes containing ASG, proton pumping and ATP-hydrolysis activity were decreased to one-tenth of those in ASG-free proteoliposomes at 15 mol% ASG; however, activity increased again slightly in the range between 20 and 40 mol% ASG. The change in proton pumping across the proteoliposome membrane is not due to a change of proteoliposome size nor to the location of the catalytic site of the tonoplast H(+)-ATPase in the proteoliposomes. SG and ASG also reduced the passive proton permeability of the proteoliposomes. These results show that SG and ASG modulate proton pumping across the tonoplast toward stimulation and depression, respectively, and they reduce the passive proton permeability of the tonoplast.

  10. Comparative Effect of Quercetin and Quercetin-3-O-β-d-Glucoside on Fibrin Polymers, Blood Clots, and in Rodent Models.

    PubMed

    Choi, Jun-Hui; Kim, Kyung-Je; Kim, Seung

    2016-11-01

    The present study evaluates the in vitro, in vivo, and ex vivo antithrombotic and anticoagulant effect of two flavonoids: quercetin and quercetin-3-O-β-d-glucoside (isoquercetin). The present results have shown that quercetin and isoquercetin inhibit the enzymatic activity of thrombin and FXa and suppress fibrin clot formation and blood clotting. The prolongation effect of quercetin and isoquercetin against epinephrine and collagen-induced platelet activation may have been caused by intervention in intracellular signaling pathways including coagulation cascade and aggregation response on platelets and blood. The in vivo and ex vivo anticoagulant efficacy of quercetin and isoquercetin was evaluated in thrombin-induced acute thromboembolism model and in ICR mice. Our findings showed that in vitro and in vivo inhibitory effects of quercetin were slightly higher than that of quercetin glucoside, whereas in vitro and ex vivo anticoagulant effects of quercetin were weaker than that of quercetin glucoside because of their structural characteristics.

  11. Conformational stability of dimeric proteins: quantitative studies by equilibrium denaturation.

    PubMed Central

    Neet, K. E.; Timm, D. E.

    1994-01-01

    The conformational stability of dimeric globular proteins can be measured by equilibrium denaturation studies in solvents such as guanidine hydrochloride or urea. Many dimeric proteins denature with a 2-state equilibrium transition, whereas others have stable intermediates in the process. For those proteins showing a single transition of native dimer to denatured monomer, the conformational stabilities, delta Gu (H2O), range from 10 to 27 kcal/mol, which is significantly greater than the conformational stability found for monomeric proteins. The relative contribution of quaternary interactions to the overall stability of the dimer can be estimated by comparing delta Gu (H2O) from equilibrium denaturation studies to the free energy associated with simple dissociation in the absence of denaturant. In many cases the large stabilization energy of dimers is primarily due to the intersubunit interactions and thus gives a rationale for the formation of oligomers. The magnitude of the conformational stability is related to the size of the polypeptide in the subunit and depends upon the type of structure in the subunit interface. The practical use, interpretation, and utility of estimation of conformational stability of dimers by equilibrium denaturation methods are discussed. PMID:7756976

  12. Photodissociation pathways and lifetimes of protonated peptides and their dimers

    SciTech Connect

    Aravind, G.; Klaerke, B.; Rajput, J.; Toker, Y.; Andersen, L. H.; Bochenkova, A. V.; Antoine, R.; Racaud, A.; Dugourd, P.; Lemoine, J.

    2012-01-07

    Photodissociation lifetimes and fragment channels of gas-phase, protonated YA{sub n} (n = 1,2) peptides and their dimers were measured with 266 nm photons. The protonated monomers were found to have a fast dissociation channel with an exponential lifetime of {approx}200 ns while the protonated dimers show an additional slow dissociation component with a lifetime of {approx}2 {mu}s. Laser power dependence measurements enabled us to ascribe the fast channel in the monomer and the slow channel in the dimer to a one-photon process, whereas the fast dimer channel is from a two-photon process. The slow (1 photon) dissociation channel in the dimer was found to result in cleavage of the H-bonds after energy transfer through these H-bonds. In general, the dissociation of these protonated peptides is non-prompt and the decay time was found to increase with the size of the peptides. Quantum RRKM calculations of the microcanonical rate constants also confirmed a statistical nature of the photodissociation processes in the dipeptide monomers and dimers. The classical RRKM expression gives a rate constant as an analytical function of the number of active vibrational modes in the system, estimated separately on the basis of the equipartition theorem. It demonstrates encouraging results in predicting fragmentation lifetimes of protonated peptides. Finally, we present the first experimental evidence for a photo-induced conversion of tyrosine-containing peptides into monocyclic aromatic hydrocarbon along with a formamide molecule both found in space.

  13. Mobile Monomers and Dimers in Precipitation Kinetics: a Microscopic Approach.

    PubMed

    Berim, Gersh O; Brim, Lana I; Ruckenstein, Eli

    2017-02-02

    A microscopic theory of precipitation kinetics in solution developed previously by Ruckenstein and co-workers [ Dadyburjor , D. B. ; Ruckenstein , E. J. Cryst. Growth 1977 , 40 , 279 - 290 ; Bhakta , A. ; Ruckenstein , E. J. Chem. Phys. 1995 , 103 , 7120 - 7135 ] is generalized. The processes (not considered in the original approach) of monomer-monomer agglomeration, leading to the creation of dimers, as well as absorption (emission) of dimers by solute particles due to dimer mobility are included in the theory. The theory is applied to a model system in which particles grow up to a certain largest size and then precipitate from solution. The most important change in the system kinetics due to those two processes (monomer agglomeration to form dimers and dimer absorption and emission) is tremendous slowing of the asymptotic time behavior of the concentration of particles of largest size. This can be used to obtain experimental evidence for agglomeration of monomers and dimer mobility in the kinetics of real systems. The effect of trimer absorption (emission) is estimated, and it is shown that it is negligible in many situations.

  14. Dimerization of mammalian kinesin-3 motors results in superprocessive motion

    PubMed Central

    Soppina, Virupakshi; Norris, Stephen R.; Dizaji, Aslan S.; Kortus, Matt; Veatch, Sarah; Peckham, Michelle; Verhey, Kristen J.

    2014-01-01

    The kinesin-3 family is one of the largest among the kinesin superfamily and its members play important roles in a wide range of cellular transport activities, yet the molecular mechanisms of kinesin-3 regulation and cargo transport are largely unknown. We performed a comprehensive analysis of mammalian kinesin-3 motors from three different subfamilies (KIF1, KIF13, and KIF16). Using Forster resonance energy transfer microscopy in live cells, we show for the first time to our knowledge that KIF16B motors undergo cargo-mediated dimerization. The molecular mechanisms that regulate the monomer-to-dimer transition center around the neck coil (NC) segment and its ability to undergo intramolecular interactions in the monomer state versus intermolecular interactions in the dimer state. Regulation of NC dimerization is unique to the kinesin-3 family and in the case of KIF13A and KIF13B requires the release of a proline-induced kink between the NC and subsequent coiled-coil 1 segments. We show that dimerization of kinesin-3 motors results in superprocessive motion, with average run lengths of ∼10 μm, and that this property is intrinsic to the dimeric kinesin-3 motor domain. This finding opens up studies on the mechanistic basis of motor processivity. Such high processivity has not been observed for any other motor protein and suggests that kinesin-3 motors are evolutionarily adapted to serve as the marathon runners of the cellular world. PMID:24706892

  15. Mechanism of dimerization of the human melanocortin 1 receptor

    SciTech Connect

    Zanna, Paola T.; Sanchez-Laorden, Berta L.; Perez-Oliva, Ana B.; Turpin, Maria C.; Herraiz, Cecilia; Jimenez-Cervantes, Celia; Garcia-Borron, Jose C.

    2008-04-04

    The melanocortin 1 receptor (MC1R) is a dimeric G protein-coupled receptor expressed in melanocytes, where it regulates the amount and type of melanins produced and determines the tanning response to ultraviolet radiation. We have studied the mechanisms of MC1R dimerization. Normal dimerization of a deleted mutant lacking the seventh transmembrane fragment and the C-terminal cytosolic extension excluded coiled-coil interactions as the basis of dimerization. Conversely, the electrophoretic pattern of wild type receptor and several Cys {yields} Ala mutants showed that four disulfide bonds are established between the monomers. Disruption of any of these bonds abolished MC1R function, but only the one involving Cys35 was essential for traffic to the plasma membrane. A quadruple Cys35-267-273-275Ala mutant migrating as a monomer in SDS-PAGE in the absence of reducing agents was able to dimerize with WT, suggesting that in addition to disulfide bond formation, dimerization involves non-covalent interactions, likely of domain swap type.

  16. Cholesterol-dependent Conformational Plasticity in GPCR Dimers

    PubMed Central

    Prasanna, Xavier; Sengupta, Durba; Chattopadhyay, Amitabha

    2016-01-01

    The organization and function of the serotonin1A receptor, an important member of the GPCR family, have been shown to be cholesterol-dependent, although the molecular mechanism is not clear. We performed a comprehensive structural and dynamic analysis of dimerization of the serotonin1A receptor by coarse-grain molecular dynamics simulations totaling 3.6 ms to explore the molecular details of its cholesterol-dependent association. A major finding is that the plasticity and flexibility of the receptor dimers increase with increased cholesterol concentration. In particular, a dimer interface formed by transmembrane helices I-I was found to be sensitive to cholesterol. The modulation of dimer interface appears to arise from a combination of direct cholesterol occupancy and indirect membrane effects. Interestingly, the presence of cholesterol at the dimer interface is correlated with increased dimer plasticity and flexibility. These results represent an important step in characterizing the molecular interactions in GPCR organization with potential relevance to therapeutic interventions. PMID:27535203

  17. Determining equilibrium constants for dimerization reactions from molecular dynamics simulations.

    PubMed

    De Jong, Djurre H; Schäfer, Lars V; De Vries, Alex H; Marrink, Siewert J; Berendsen, Herman J C; Grubmüller, Helmut

    2011-07-15

    With today's available computer power, free energy calculations from equilibrium molecular dynamics simulations "via counting" become feasible for an increasing number of reactions. An example is the dimerization reaction of transmembrane alpha-helices. If an extended simulation of the two helices covers sufficiently many dimerization and dissociation events, their binding free energy is readily derived from the fraction of time during which the two helices are observed in dimeric form. Exactly how the correct value for the free energy is to be calculated, however, is unclear, and indeed several different and contradictory approaches have been used. In particular, results obtained via Boltzmann statistics differ from those determined via the law of mass action. Here, we develop a theory that resolves this discrepancy. We show that for simulation systems containing two molecules, the dimerization free energy is given by a formula of the form ΔG ∝ ln(P(1) /P(0) ). Our theory is also applicable to high concentrations that typically have to be used in molecular dynamics simulations to keep the simulation system small, where the textbook dilute approximations fail. It also covers simulations with an arbitrary number of monomers and dimers and provides rigorous error estimates. Comparison with test simulations of a simple Lennard Jones system with various particle numbers as well as with reference free energy values obtained from radial distribution functions show full agreement for both binding free energies and dimerization statistics.

  18. Crosslinking Evidence for Motional Constraints within Chemoreceptor Trimers of Dimers

    PubMed Central

    Massazza, Diego A.; Parkinson, John S.; Studdert, Claudia A.

    2011-01-01

    Chemotactic behavior in bacteria relies on the sensing ability of large chemoreceptor clusters that are usually located at the cell pole. In E. coli, chemoreceptors show higher order interactions within those clusters based on a trimer-of-dimers organization. This architecture is conserved in a variety of other bacteria and archaea, implying that receptors in many microorganisms form trimer of dimer signaling teams. To gain further insight into the assembly and dynamic behavior of receptor trimers of dimers, we used in vivo crosslinking targeted to cysteine residues at various positions that define six different levels along the cytoplasmic signaling domains of the aspartate and serine chemoreceptors, Tar and Tsr. We found that the cytoplasmic domains of these receptors are close to each other near the trimer contact region at the cytoplasmic tip and lie farther apart as the receptor dimers approach the cytoplasmic membrane. Tar and Tsr reporter sites within the same or closely adjacent levels readily formed mixed crosslinks, whereas reporters lying at different distances from the tip did not. These findings indicate that there are no significant vertical displacements of one dimer with respect to the others within the trimer unit. Attractant stimuli had no discernable effect on the crosslinking efficiency of any of the reporters tested, but a strong osmotic stimulus reproducibly enhanced crosslinking at most of the reporter sites, indicating that individual dimers may move closer together under this condition. PMID:21174433

  19. The photophysics of naphthalene dimers controlled by sulfur bridge oxidation.

    PubMed

    Climent, Clàudia; Barbatti, Mario; Wolf, Michael O; Bardeen, Christopher J; Casanova, David

    2017-07-01

    In this study we investigate in detail the photophysics of naphthalene dimers covalently linked by a sulfur atom. We explore and rationalize how the oxidation state of the sulfur-bridging atom directly influences the photoluminescence of the dimer by enhancing or depriving its radiative and non-radiative relaxation pathways. In particular, we discuss how oxidation controls the amount of electronic transfer between the naphthalene moieties and the participation of the SO n bridge in the low-lying electronic transitions. We identify the sulfur electron lone-pairs as crucial actors in the non-radiative decay of the excited sulfide and sulfoxide dimers, which are predicted to proceed via a conical intersection (CI). Concretely, two types of CI have been identified for these dimers, which are associated with the photo-induced pyramidal inversion and reverse fragmentation mechanisms found in aryl sulfoxide dimers. The obtained results and conclusions are general enough to be extrapolated to other sulfur-bridged conjugated dimers, therefore proportionating novel strategies in the design of strongly photoluminescent organic molecules with controlled charge transfer.

  20. Magneto-association near an atom-dimer resonance

    NASA Astrophysics Data System (ADS)

    Luo, D.; Nguyen, J. H. V.; Hulet, R. G.

    2015-05-01

    Over the past decade the universal scaling of Efimov trimers has been explored in various atomic species by measuring the three-body loss coefficient. An enhancement of the three-body loss at the atom-dimer resonance has been observed, but remains unexplained. It has been attributed to an ``avanlanche mechanism'' based on resonant atom-dimer scattering, yet the effectiveness of the hypothesis is under scrutiny. We present a new piece to the puzzle. In our work, Feshbach dimers and Efimov trimers are formed near the atom-dimer resonance by RF-association, from a Bose-Einstein condensate of 7Li atoms. The molecular binding energies are tunable by the broad Feshbach resonance of the atoms in the | 1 , 1 > state. We observe that the dimer formation rate is significantly enhanced at the atom-dimer resonance. The origin of this enhanement is unclear, but it may be closely related to the enhancement of the three-body loss rate. Work supported by the NSF, ARO, and the Welch Foundation.

  1. Occurrence and fate of the norsesquiterpene glucoside ptaquiloside (PTA) in soils

    NASA Astrophysics Data System (ADS)

    Zaccone, Claudio; Cavoski, Ivana; Costi, Roberta; Sarais, Giorgia; Caboni, Pierluigi; Miano, Teodoro M.; Lattanzio, Vincenzo

    2014-05-01

    The bracken fern Pteridium aquilinum (L.) Kuhn, one of the most common plant species on Earth, produces a wide range of secondary metabolites including the norsesquiterpene glucoside ptaquiloside (PTA). This bracken constituent causes acute poisoning, blindness and cancer in animals, and can be transferred to man when bracken is utilized as food. Also milk from cows eating bracken is thought to be the vector for the transfer of PTA to humans, as well as PTA-contaminated drinking waters. Although some studies on the effect of growth conditions and soil properties on the production and mobility of PTA have been carried out (mainly in the North of Europe), results are sometimes conflicting and further investigations are needed. The aim of the present work is to study the occurrence and the fate of PTA in soils showing different physico-chemical features, collected in different pedoclimatic areas (from the South of Italy), but having the extensive ("wild") livestock farming as common denominator. The PTA content was determined in both soil and fern samples by GC-MS; both the extraction protocol and recovery were previously tested through incubation studies. Soils samples were also characterizes from the physical and chemical point of view (pH, EC, texture, total carbonates, cation exchange capacity, organic C, total N, available nutrients and heavy metal concentration) in order to correlate the possible influence of soil parameters on PTA production, occurrence and mobility. PTA concentration in soil samples was always

  2. Metabolism of monoterpenes: early steps in the metabolism of d-neomenthyl-. beta. -D-glucoside in peppermint (Mentha piperita) rhizomes

    SciTech Connect

    Croteau, R.; Sood, V.K.; Renstroem, B.; Bhushan, R.

    1984-11-01

    Previous studies have shown that the monoterpene ketone l-(G-/sup 3/H) menthone is reduced to the epimeric alcohols l-menthol and d-neomenthol in leaves of flowering peppermint (Mentha piperita L.), and that a portion of the menthol is converted to methyl acetate while the bulk of the neomenthol is transformed to neomenthyl-..beta..-D-glucoside which is then transported to the rhizome. Analysis of the disposition of l-(G)/sup 3/H)menthone applied to midstem leaves of intact flowering plants allowed the kinetics of synthesis and transport of the monoterpenyl glucoside to be determined, and gave strong indication that the glucoside was subsequently metabolized in the rhizome. Studies with d-(G-/sup 3/H)neomenthyl-..beta..-D-glucoside as substrate, using excised rhizomes or rhizome segments, confirmed the hydrolysis of the glucoside as an early step in metabolism at this site, and revealed that the terpenoid moiety was further converted to a series of ether-soluble, methanol-soluble, and water-soluble products. The conversion of menthone to the lactone, and of the lactone to more polar products, were confirmed in vivo using l-(G-/sup 3/H)menthone and l-(G-/sup 3/H)-3,4-menthone lactone as substrates. Additional oxidation products were formed in vivo via the desaturation of labeled neomenthol and/or menthone, but none of these transformations appeared to lead to ring opening of the p-menthane skeleton. Each step in the main reaction sequence, from hydrolysis of neomenthyl glucoside to lactonization of menthone, was demonstrated in cell-free extracts from the rhizomes of flowering mint plants. The lactomization step is of particular significance in providing a means of cleaving the p-methane ring to afford an acyclic carbon skeleton that can be further degraded by modifications of the well-known ..beta..-oxidation sequence. 41 references, 3 figures, 1 table.

  3. Mass Analyzed Threshold Ionization of Lutetium Dimer

    NASA Astrophysics Data System (ADS)

    Wu, Lu; Roudjane, Mourad; Liu, Yang; Yang, Dong-Sheng

    2013-06-01

    Lu_2 is produced in a pulsed laser-vaporization metal-cluster source and studied by mass-analyzed threshold ionization (MATI) spectroscopy. The MATI spectrum displays several long progressions from the transitions between various vibrational levels of the neutral and ion electronic states. From the spectrum, the upper limit of the ionization energy of the dimer is determined to be 43996 cm^{-1}, and the vibrational frequencies are measured to be 121 cm^{-1} in the neutral state and 90 cm^{-1} in the ion state. By combining with ab initio calculations at CASPT2 level, the ground state of Lu_2 is identified as ^3Σ_g^-. The ^3Σ_g^- state has an electron configuration of 6sσ_g^25dπ_u^15dπ_u^16sσ_u^2, which is formed by the interactions of two Lu atoms in the ^2D(5d6s^2) ground state. Ionization of the neutral state removes a 5dπ_u bonding electron and yields a ion state with a considerably longer bond distance. Lu_2 has a very different bonding feature from La_2, for which a ^1Σ_g^+ ground state was previously identified with an electron configuration of 5dπ_u^46sσ_g^2 formed by the interactions of two La atoms in the ^4F(5d^26s) excited state. Yang Liu, Lu Wu, Chang-Hua Zhang, Serge A. Krasnokutski, and Dong-Sheng Yang, J. Chem. Phys. 135, 034309 (2011).

  4. UVA Generates Pyrimidine Dimers in DNA Directly

    PubMed Central

    Jiang, Yong; Rabbi, Mahir; Kim, Minkyu; Ke, Changhong; Lee, Whasil; Clark, Robert L.; Mieczkowski, Piotr A.; Marszalek, Piotr E.

    2009-01-01

    There is increasing evidence that UVA radiation, which makes up ∼95% of the solar UV light reaching the Earth's surface and is also commonly used for cosmetic purposes, is genotoxic. However, in contrast to UVC and UVB, the mechanisms by which UVA produces various DNA lesions are still unclear. In addition, the relative amounts of various types of UVA lesions and their mutagenic significance are also a subject of debate. Here, we exploit atomic force microscopy (AFM) imaging of individual DNA molecules, alone and in complexes with a suite of DNA repair enzymes and antibodies, to directly quantify UVA damage and reexamine its basic mechanisms at a single-molecule level. By combining the activity of endonuclease IV and T4 endonuclease V on highly purified and UVA-irradiated pUC18 plasmids, we show by direct AFM imaging that UVA produces a significant amount of abasic sites and cyclobutane pyrimidine dimers (CPDs). However, we find that only ∼60% of the T4 endonuclease V-sensitive sites, which are commonly counted as CPDs, are true CPDs; the other 40% are abasic sites. Most importantly, our results obtained by AFM imaging of highly purified native and synthetic DNA using T4 endonuclease V, photolyase, and anti-CPD antibodies strongly suggest that CPDs are produced by UVA directly. Thus, our observations contradict the predominant view that as-yet-unidentified photosensitizers are required to transfer the energy of UVA to DNA to produce CPDs. Our results may help to resolve the long-standing controversy about the origin of UVA-produced CPDs in DNA. PMID:19186150

  5. Analysis of the metabolites of isorhamnetin 3-O-glucoside produced by human intestinal flora in vitro by applying ultraperformance liquid chromatography/quadrupole time-of-flight mass spectrometry.

    PubMed

    Du, Le-yue; Zhao, Min; Xu, Jun; Qian, Da-wei; Jiang, Shu; Shang, Er-xin; Guo, Jian-ming; Duan, Jin-ao

    2014-03-26

    Isorhamnetin 3-O-glucoside, which is widely contained in many vegetables and rice, is expected to be metabolized by intestinal microbiota after digestion, which brings about the profile of its pharmacological effect. However, little is known about the interactions between this active ingredient and the intestinal flora. In this study, the preculture bacteria and GAM (general anaerobic medium) broth with isorhamnetin 3-O-glucoside were mixed for 48 h of incubation. Ultraperformance liquid chromatography/quadrupole time-of-flight mass spectrometry was used for analysis of the metabolites of isorhamnetin 3-O-glucoside in the corresponding supernatants of fermentation. The parent and five metabolites were found and preliminarily identified on the basis of the chromatograms and characteristics of their protonated ions. Four main metabolic pathways, including deglycosylation, demethoxylation, dehydroxylation, and acetylation, were summarized to explain how the metabolites were converted. Acetylated isorhamnetin 3-O-glucoside and kaempferol 3-O-glucoside were detected only in the sample of Escherichia sp. 12, and quercetin existed only in the sample of Escherichia sp. 4. However, the majority of bacteria could metabolize isorhamnetin 3-O-glucoside to its aglycon isorhamnetin, and then isorhamnetin was degraded to kaempferol. The metabolic pathway and the metabolites of isorhamnetin 3-O-glucoside yielded by different isolated human intestinal bacteria were investigated for the first time. The results probably provided useful information for further in vivo metabolism and active mechanism research on isorhamnetin 3-O-glucoside.

  6. Phenolic dimers and an indole alkaloid from Campylospermum flavum (Ochnaceae).

    PubMed

    Ndongo, Joseph Thierry; Shaaban, Mohamed; Mbing, Joséphine Ngo; Bikobo, Dominique Ngono; Atchadé, Alex de Théodore; Pegnyemb, Dieudonné Emmanuel; Laatsch, Hartmut

    2010-11-01

    From the leaves and stem bark of Campylospermum flavum (Ochnaceae), three compounds, namely 4‴-O-methylagathisflavone, flavumchalcone, and flavumindole have been isolated together with 10 known compounds, including three flavonoids, two biflavonoids, two alkaloids, two nitrile glucosides, and glucopyranosyl-β-sistosterol. The structures of these compounds and their relative configurations were established by 1D and 2D NMR experiments. The methanolic crude extracts of leaves and stem bark of C. flavum and compounds displayed a significant cytotoxicity towards Artemia salina larvae.

  7. Crotocascarins I-K: Crotofolane-Type Diterpenoids, Crotocascarin γ, Isocrotofolane Glucoside and Phenolic Glycoside from the Leaves of Croton cascarilloides.

    PubMed

    Kawakami, Susumu; Matsunami, Katsuyoshi; Otsuka, Hideaki; Inagaki, Masanori; Takeda, Yoshio; Kawahata, Masatoshi; Yamaguchi, Kentaro

    2015-01-01

    From the 1-BuOH-soluble fraction of a methanol (MeOH) extract of the leaves of Croton cascarilloides, crotofolanes: crotocascarins I-K, nor-crotofolane: crotocascarin γ, isocrotofolane glucoside and phenolic glycoside were isolated by a combination of various separation techniques. Their structures were elucidated mainly from the NMR spectroscopic evidence. The structure of crotocascarin K was first elucidated by spectroscopic analysis and then was confirmed by X-ray crystallographic analysis. Its absolute structure was finally determined by the modified Mosher's method. Isocrotofolane glucoside was found to possess a new skeleton, however, its absolute structure remains to be determined.

  8. Occurrence of different trichothecenes and deoxynivalenol-3-β-D-glucoside in naturally and artificially contaminated Danish cereal grains and whole maize plants.

    PubMed

    Rasmussen, P H; Nielsen, K F; Ghorbani, F; Spliid, N H; Nielsen, G C; Jørgensen, L N

    2012-08-01

    Fusarium mycotoxins such as deoxynivalenol (DON) can occur in cereals conjugated to glucose and probably also to other sugars. These conjugates, which are often referred to as "masked mycotoxins", will not be detected with routine analytical techniques. Furthermore, it is suspected that the parent toxin may again be released after hydrolysis in the digestive tracts of animals and humans. Today, our knowledge of the occurrence of these compounds in cereal grains is limited. In this paper, a LC-MS/MS method for the simultaneous determination of DON, deoxynivalenol-3-β-D-glucoside (DON-3-glucoside), 3 acetyl-DON, nivalenol, fusarenon-X, diacetoxyscirpenol, HT-2 toxin, and T-2 toxin in naturally (n = 48) and artificially (n = 30) contaminated cereal grains (wheat, barley, oat, rye triticale) is reported. The method has also been applied to whole fresh maize plant intended for production of maize silage (n = 10). The samples were collected from the harvest years 2006-2010, The results show that DON-3-glucoside and DON co-occurred in cereal grains and, especially in several of the highly contaminated samples, the concentration of the glucoside can be relatively high, corresponding to over 37 % of the DON concentration. The DON-3-glucoside levels in both the naturally and in the artificially grain inoculated with Fusarium were second only to DON, and were generally higher than those of the other tested trichothecenes, which were found at low concentrations in most samples, in many cases even below the detection limit of the method. This argues for the importance of taking DON-3-glucoside into account in the ongoing discussion within the European Community concerning exposure re-evaluations for setting changed values for the tolerable intake for DON. Our results indicate that, in the naturally contaminated grains and in the Fusarium infested cereal grains (winter and spring wheat, oat, triticale), the concentration level of DON-3-glucoside is positively

  9. Dirigent Protein-Mediated Lignan and Cyanogenic Glucoside Formation in Flax Seed: Integrated Omics and MALDI Mass Spectrometry Imaging.

    PubMed

    Dalisay, Doralyn S; Kim, Kye Won; Lee, Choonseok; Yang, Hong; Rübel, Oliver; Bowen, Benjamin P; Davin, Laurence B; Lewis, Norman G

    2015-06-26

    An integrated omics approach using genomics, transcriptomics, metabolomics (MALDI mass spectrometry imaging, MSI), and bioinformatics was employed to study spatiotemporal formation and deposition of health-protecting polymeric lignans and plant defense cyanogenic glucosides. Intact flax (Linum usitatissimum) capsules and seed tissues at different development stages were analyzed. Transcriptome analyses indicated distinct expression patterns of dirigent protein (DP) gene family members encoding (-)- and (+)-pinoresinol-forming DPs and their associated downstream metabolic processes, respectively, with the former expressed at early seed coat development stages. Genes encoding (+)-pinoresinol-forming DPs were, in contrast, expressed at later development stages. Recombinant DP expression and DP assays also unequivocally established their distinct stereoselective biochemical functions. Using MALDI MSI and ion mobility separation analyses, the pinoresinol downstream derivatives, secoisolariciresinol diglucoside (SDG) and SDG hydroxymethylglutaryl ester, were localized and detectable only in early seed coat development stages. SDG derivatives were then converted into higher molecular weight phenolics during seed coat maturation. By contrast, the plant defense cyanogenic glucosides, the monoglucosides linamarin/lotaustralin, were detected throughout the flax capsule, whereas diglucosides linustatin/neolinustatin only accumulated in endosperm and embryo tissues. A putative biosynthetic pathway to the cyanogens is proposed on the basis of transcriptome coexpression data. Localization of all metabolites was at ca. 20 μm resolution, with the web based tool OpenMSI enabling not only resolution enhancement but also an interactive system for real-time searching for any ion in the tissue under analysis.

  10. Heterologous expression of Arabidopsis UDP-glucosyltransferases in Saccharomyces cerevisiae for production of zearalenone-4-O-glucoside.

    PubMed

    Poppenberger, Brigitte; Berthiller, Franz; Bachmann, Herwig; Lucyshyn, Doris; Peterbauer, Clemens; Mitterbauer, Rudolf; Schuhmacher, Rainer; Krska, Rudolf; Glössl, Josef; Adam, Gerhard

    2006-06-01

    Zearalenone, a secondary metabolite produced by several plant-pathogenic fungi of the genus Fusarium, has high estrogenic activity in vertebrates. We developed a Saccharomyces cerevisiae bioassay strain that we used to identify plant genes encoding UDP-glucosyltransferases that can convert zearalenone into zearalenone-4-O-glucoside (ZON-4-O-Glc). Attachment of the glucose moiety to zearalenone prevented the interaction of the mycotoxin with the human estrogen receptor. We found that two of six clustered, similar UGT73C genes of Arabidopsis thaliana encode glucosyltransferases that can inactivate zearalenone in the yeast bioassay. The formation of glucose conjugates seems to be an important plant mechanism for coping with zearalenone but may result in significant amounts of "masked" zearalenone in Fusarium-infected plant products. Due to the unavailability of an analytical standard, the ZON-4-O-Glc is not measured in routine analytical procedures, even though it can be converted back to active zearalenone in the digestive tracts of animals. Zearalenone added to yeast transformed with UGT73C6 was converted rapidly and efficiently to ZON-4-O-Glc, suggesting that the cloned UDP-glucosyltransferase could be used to produce reference glucosides of zearalenone and its derivatives.

  11. Heterologous Expression of Arabidopsis UDP-Glucosyltransferases in Saccharomyces cerevisiae for Production of Zearalenone-4-O-Glucoside

    PubMed Central

    Poppenberger, Brigitte; Berthiller, Franz; Bachmann, Herwig; Lucyshyn, Doris; Peterbauer, Clemens; Mitterbauer, Rudolf; Schuhmacher, Rainer; Krska, Rudolf; Glössl, Josef; Adam, Gerhard

    2006-01-01

    Zearalenone, a secondary metabolite produced by several plant-pathogenic fungi of the genus Fusarium, has high estrogenic activity in vertebrates. We developed a Saccharomyces cerevisiae bioassay strain that we used to identify plant genes encoding UDP-glucosyltransferases that can convert zearalenone into zearalenone-4-O-glucoside (ZON-4-O-Glc). Attachment of the glucose moiety to zearalenone prevented the interaction of the mycotoxin with the human estrogen receptor. We found that two of six clustered, similar UGT73C genes of Arabidopsis thaliana encode glucosyltransferases that can inactivate zearalenone in the yeast bioassay. The formation of glucose conjugates seems to be an important plant mechanism for coping with zearalenone but may result in significant amounts of “masked” zearalenone in Fusarium-infected plant products. Due to the unavailability of an analytical standard, the ZON-4-O-Glc is not measured in routine analytical procedures, even though it can be converted back to active zearalenone in the digestive tracts of animals. Zearalenone added to yeast transformed with UGT73C6 was converted rapidly and efficiently to ZON-4-O-Glc, suggesting that the cloned UDP-glucosyltransferase could be used to produce reference glucosides of zearalenone and its derivatives. PMID:16751557

  12. Mesitylene-Cored Glucoside Amphiphiles (MGAs) for Membrane Protein Studies: Importance of Alkyl Chain Density in Detergent Efficacy

    PubMed Central

    Cho, Kyung Ho; Ribeiro, Orquidea; Du, Yang; Tikhonova, Elena; Mortensen, Jonas S.; Markham, Kelsey; Hariharan, Parameswaran; Loland, Claus J.; Guan, Lan; Kobilka, Brian K.; Byrne, Bernadette

    2017-01-01

    Detergents serve as useful tools for membrane protein structural and functional studies. Their amphipathic nature allows detergents to associate with the hydrophobic regions of membrane proteins whilst maintaining the proteins in aqueous solution. However, widely used conventional detergents are limited in their ability to maintain the structural integrity of membrane proteins and thus there are major efforts underway to develop novel agents with improved properties. We prepared mesitylene-cored glucoside amphiphiles (MGAs) with three alkyl chains and compared these agents with previously developed xylene-linked maltoside agents (XMAs) with two alkyl chains and a conventional detergent (DDM). When these agents were evaluated for four membrane proteins including a G protein-coupled receptor (GPCR), some agents such as MGA-C13 and MGA-C14 resulted in markedly enhanced stability of membrane proteins compared to both DDM and the XMAs. This favourable behaviour is due likely to the increased hydrophobic density provided by the extra alkyl chain. Thus, this study not only describes new glucoside agents with potential for membrane protein research, but also introduces a new detergent design principle for future development. PMID:27743406

  13. Molecular cloning and characterization of an enzyme hydrolyzing p-nitrophenyl alpha-D-glucoside from Bacillus stearothermophilus SA0301.

    PubMed

    Kobayashi, Atsushi; Tonozuka, Takashi; Sato, Kimihiko; Suyama, Mikita; Sasaki, Jun; Nyamdawaa, Batbold; Sakaguchi, Masayoshi; Sakano, Yoshiyuki

    2006-02-01

    Bacillus stearothermophilus SA0301 produces an extracellular oligo-1,6-glucosidase (bsO16G) that also hydrolyzes p-nitrophenyl alpha-D-glucoside (Tonozuka et al., J. Appl. Glycosci., 45, 397-400 (1998)). We cloned a gene for an enzyme hydrolyzing p-nitrophenyl alpha-D-glucoside, which was different from the one mentioned above, from B. stearothermophilus SA0301. The k(0)/K(m) values of bsO16G for isomaltotriose and isomaltose were 13.2 and 1.39 s(-1).mM(-1) respectively, while the newly cloned enzyme did not hydrolyze isomaltotriose, and the k(0)/K(m) value for isomaltose was 0.81 s(-1).mM(-1). The primary structure of the cloned enzyme more closely resembled those of trehalose-6-phosphate hydrolases than those of oligo-1,6-glucosidases, and the cloned enzyme hydrolyzed trehalose 6-phosphate. An open reading frame encoding a protein homologous to the trehalose-specific IIBC component of the phopshotransferase system was also found upstream of the gene for this enzyme.

  14. High-resolution MALDI mass spectrometry imaging of gallotannins and monoterpene glucosides in the root of Paeonia lactiflora

    NASA Astrophysics Data System (ADS)

    Li, Bin; Bhandari, Dhaka Ram; Römpp, Andreas; Spengler, Bernhard

    2016-10-01

    High-resolution atmospheric-pressure scanning microprobe matrix-assisted laser desorption/ionization mass spectrometry imaging (AP-SMALDI MSI) at 10 μm pixel size was performed to unravel the spatio-chemical distribution of major secondary metabolites in the root of Paeonia lactiflora. The spatial distributions of two major classes of bioactive components, gallotannins and monoterpene glucosides, were investigated and visualized at the cellular level in tissue sections of P. lactiflora roots. Accordingly, other primary and secondary metabolites were imaged, including amino acids, carbohydrates, lipids and monoterpenes, indicating the capability of untargeted localization of metabolites by using high-resolution MSI platform. The employed AP-SMALDI MSI system provides significant technological advancement in the visualization of individual molecular species at the cellular level. In contrast to previous histochemical studies of tannins using unspecific staining reagents, individual gallotannin species were accurately localized and unequivocally discriminated from other phenolic components in the root tissues. High-quality ion images were obtained, providing significant clues for understanding the biosynthetic pathway of gallotannins and monoterpene glucosides and possibly helping to decipher the role of tannins in xylem cells differentiation and in the defence mechanisms of plants, as well as to investigate the interrelationship between tannins and lignins.

  15. [Effect of algorithms for calibration set selection on quantitatively determining asiaticoside content in Centella total glucosides by near infrared spectroscopy].

    PubMed

    Zhan, Xue-yan; Zhao, Na; Lin, Zhao-zhou; Wu, Zhi-sheng; Yuan, Rui-juan; Qiao, Yan-jiang

    2014-12-01

    The appropriate algorithm for calibration set selection was one of the key technologies for a good NIR quantitative model. There are different algorithms for calibration set selection, such as Random Sampling (RS) algorithm, Conventional Selection (CS) algorithm, Kennard-Stone(KS) algorithm and Sample set Portioning based on joint x-y distance (SPXY) algorithm, et al. However, there lack systematic comparisons between two algorithms of the above algorithms. The NIR quantitative models to determine the asiaticoside content in Centella total glucosides were established in the present paper, of which 7 indexes were classified and selected, and the effects of CS algorithm, KS algorithm and SPXY algorithm for calibration set selection on the accuracy and robustness of NIR quantitative models were investigated. The accuracy indexes of NIR quantitative models with calibration set selected by SPXY algorithm were significantly different from that with calibration set selected by CS algorithm or KS algorithm, while the robustness indexes, such as RMSECV and |RMSEP-RMSEC|, were not significantly different. Therefore, SPXY algorithm for calibration set selection could improve the predicative accuracy of NIR quantitative models to determine asiaticoside content in Centella total glucosides, and have no significant effect on the robustness of the models, which provides a reference to determine the appropriate algorithm for calibration set selection when NIR quantitative models are established for the solid system of traditional Chinese medcine.

  16. Gastrointestinal absorption and metabolism of hesperetin-7-O-rutinoside and hesperetin-7-O-glucoside in healthy humans.

    PubMed

    Actis-Goretta, Lucas; Dew, Tristan P; Lévèques, Antoine; Pereira-Caro, Gema; Rein, Maarit; Teml, Alexander; Schäfer, Christian; Hofmann, Ute; Schwab, Matthias; Eichelbaum, Michel; Crozier, Alan; Williamson, Gary

    2015-09-01

    Hesperetin-7-O-rutinoside (hesperidin) reduces blood pressure in healthy volunteers but its intestinal absorption and metabolism are not fully understood. Therefore, we aimed to determine sites of absorption and metabolism of dietary flavanone glycosides in humans. Using a single-blind, randomized crossover design, we perfused equimolar amounts of hesperetin-7-O-rutinoside and hesperetin-7-O-glucoside directly into the proximal jejunum of healthy volunteers. We assessed the appearance of metabolites in the perfusate, blood and urine, to determine the sites of metabolism and excretion, and compared this to oral administration. The glucoside was rapidly hydrolyzed by brush border enzymes without any contribution from pancreatic, stomach, or other secreted enzymes, or from bacterial enzymes. Only ∼3% of the dose was recovered intact in the perfusate, indicating high absorption. A proportion was effluxed directly back into the perfused segment mainly in the form of hesperetin-3'-O-sulfate. In contrast, very little hydrolysis or absorption of hesperetin-7-O-rutinoside was observed with ∼80% recovered in the perfusate, no hesperetin metabolites were detected in blood and only traces were excreted in urine. The data elucidate the pathways of metabolism of dietary hesperidin in vivo and will facilitate better design of mechanistic studies both in vivo and in vitro. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. In vitro evaluation of the effects of protein-polyphenol-polysaccharide interactions on (+)-catechin and cyanidin-3-glucoside bioaccessibility.

    PubMed

    Oliveira, Ana; Pintado, Manuela

    2015-11-01

    The bioaccessibility of cyanidin-3-glucoside and (+)-catechin in model solutions when β-lactoglobulin (β-LG) and pectin/chitosan are present was investigated using an in vitro model simulating gastrointestinal conditions. In the mouth, the free cyanidin content increased (+) 90 and 14% while the (+)-catechin content decreased (-) 23 and 13%, respectively for mixtures with -pectin and -β-LG-pectin. Under gastric conditions, the cyanidin content decreased 85 and 28% for mixtures with -pectin and -β-LG-pectin. On the contrary, after gastric digestion, (+)-catechin bioaccessibility increased and exhibited values similar to the original samples for all the systems tested. The transition to the intestinal environment induced a significant alteration on both polyphenols and this effect was more marked for cyanidin. Systems with pectin allowed obtaining a higher content of bioaccessible cyanidin. The gastric conditions promoted an increase in the antioxidant capacity, followed by a decrease of it in the intestine. The free (+)-catechin and cyanidin-3-glucoside contents decreased when exposed to the gastrointestinal tract conditions. However, when incorporated in food matrix components, the gastrointestinal tract may act positively on the extraction of polyphenols, since they are progressively released from protein and polysaccharide bonds, being available for the absorption and to exert their biological effects.

  18. Hexaconazole induces antioxidant protection and apigenin-7-glucoside accumulation in Matricaria chamomilla plants subjected to drought stress.

    PubMed

    Hojati, Mostafa; Modarres-Sanavy, Seyed Ali Mohammad; Ghanati, Faezeh; Panahi, Mehdi

    2011-05-15

    In this experiment, the possibility of enhancing the water deficit stress tolerance of chamomile (Matricaria chamomilla L.) during two growth stages by the exogenous application of hexaconazole (HEX) was investigated. To improve water deficit tolerance, HEX was applied in three concentrations during two different stages (50 and 80 days after sowing). After HEX applications, the plants were subjected to water deficit stress. Although all HEX concentrations improved the water deficit stress tolerance in chamomile plants, the application of 15 mg L(-1) provided better protection when compared to the other concentration. The exogenous application of HEX provided significant protection against water deficit stress compared to non-HEX-treated plants, significantly affecting the morphological characteristics and aspects of productivity, the relative water, protein and proline contents; non-enzymatic and enzymatic antioxidants; and the flower's apigenin-7-glucoside content. These results suggest that the HEX-induced tolerance to water deficit stress in chamomile was related to the changes in growth variables, antioxidants and the apigenin-7-glucoside content.

  19. High-resolution MALDI mass spectrometry imaging of gallotannins and monoterpene glucosides in the root of Paeonia lactiflora

    PubMed Central

    Li, Bin; Bhandari, Dhaka Ram; Römpp, Andreas; Spengler, Bernhard

    2016-01-01

    High-resolution atmospheric-pressure scanning microprobe matrix-assisted laser desorption/ionization mass spectrometry imaging (AP-SMALDI MSI) at 10 μm pixel size was performed to unravel the spatio-chemical distribution of major secondary metabolites in the root of Paeonia lactiflora. The spatial distributions of two major classes of bioactive components, gallotannins and monoterpene glucosides, were investigated and visualized at the cellular level in tissue sections of P. lactiflora roots. Accordingly, other primary and secondary metabolites were imaged, including amino acids, carbohydrates, lipids and monoterpenes, indicating the capability of untargeted localization of metabolites by using high-resolution MSI platform. The employed AP-SMALDI MSI system provides significant technological advancement in the visualization of individual molecular species at the cellular level. In contrast to previous histochemical studies of tannins using unspecific staining reagents, individual gallotannin species were accurately localized and unequivocally discriminated from other phenolic components in the root tissues. High-quality ion images were obtained, providing significant clues for understanding the biosynthetic pathway of gallotannins and monoterpene glucosides and possibly helping to decipher the role of tannins in xylem cells differentiation and in the defence mechanisms of plants, as well as to investigate the interrelationship between tannins and lignins. PMID:27796322

  20. Structure elucidation of Sch 20562, a glucosidic cyclic dehydropeptide lactone--the major component of W-10 antifungal antibiotic.

    PubMed

    Afonso, A; Hon, F; Brambilla, R

    1999-04-01

    A novel bacterium designated as Aeromonas sp. W-10 produces the antibiotic W-10 complex which comprises of two major and several minor components. The two major components from this complex, Sch 20562 (1) and Sch 20561 (1a), are of biological interest in view of their potent antifungal activity. The chemical degradation studies utilized for the assignment of structure 1 for Sch 20562 are described here. Some of the noteworthy diversity of structural features in this glucosidic cyclic dehydrononapeptide lactone 1 are: an N-terminal (D)-beta-hydroxymyristyl unit, three D-amino acid units, two (E)-alpha-aminocrotonyl units, and an O-alpha-D-glucosyl-N-methyl-L-allo-threonine unit. The structure determination of 1 utilized the selective cleavage of the dehydropeptide units by ozonolysis to form fragments that were sequenced by mass spectrometry. The stereochemistry of the amino acid units were assigned by isolation of the free amino acids from the hydrolysates of the fragments. The stereochemistry of the alpha-aminocrotonyl units and the glucosidic linkage were assigned by nmr spectroscopy and molecular rotation data.