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

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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).

  7. [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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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...

  1. 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.

  2. 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

  3. 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).

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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...

  9. 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...

  10. 21 CFR 573.660 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Methyl glucoside-coconut oil ester. 573.660... ANIMALS Food Additive Listing § 573.660 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester may be safely used in accordance with the following conditions: (a) The additive meets...

  11. 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...

  12. 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... ANIMALS Food Additive Listing § 573.660 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester may be safely used in accordance with the following conditions: (a) The additive meets...

  13. 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...

  14. 21 CFR 573.660 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Methyl glucoside-coconut oil ester. 573.660... ANIMALS Food Additive Listing § 573.660 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester may be safely used in accordance with the following conditions: (a) The additive meets...

  15. 21 CFR 573.660 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Methyl glucoside-coconut oil ester. 573.660... ANIMALS Food Additive Listing § 573.660 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester may be safely used in accordance with the following conditions: (a) The additive meets...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 21 CFR 573.660 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Methyl glucoside-coconut oil ester. 573.660... ANIMALS Food Additive Listing § 573.660 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester may be safely used in accordance with the following conditions: (a) The additive meets...

  1. 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...

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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%.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. [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.

  14. 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.

  15. 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).

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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).

  6. 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).

  7. 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.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  9. 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.

  10. 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

  11. A new abietic acid-type diterpene glucoside from the needles of Pinus densiflora.

    PubMed

    Jung, Mee Jung; Jung, Hyun Ah; Kang, Sam Sik; Hwang, Geum-Sook; Choi, Jae Sue

    2009-12-01

    From the ethyl acetate fraction of the methanol extract of the needles of Pinus densiflora (Pinaceae), a new diterpenoid glucoside [9alpha,13alpha-epoxy-8beta,14beta-dihydroxy-abietic acid-18-O-beta-D: -glucopyranoside] (1), two flavonoid glucosides [kaempferol 3-O-beta-D: -glucoside (2) and 6-C-methyl kaempferol 3-O-beta-D: -glucoside (3)], and two monoterpenoid glucosides [bornyl 6-O-alpha-Larabinofuranosyl (1-->6)-beta-D: -glucopyranoside (4) and bornyl 6-O-beta-D: -apiofuranosyl (1-->6)-beta-D: -glucopyranoside (5)] were isolated and characterized on the basis of spectral analysis. Of all the compounds, 2 and 3 showed peroxynitrite scavenging activity.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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).

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  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. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  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. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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).

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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}.

  15. 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.

  16. Universal four-Boson states in ultracold molecular gases: resonant effects in dimer-dimer collisions.

    PubMed

    D'Incao, J P; von Stecher, J; Greene, Chris H

    2009-07-17

    We study the manifestations of universal four-body physics in ultracold dimer-dimer collisions. We show that resonant features associated with three-body Efimov physics and dimer-dimer scattering lengths are universally related. The emergence of universal four-boson states allows for the tunability of the dimer-dimer interaction, thus enabling the future study of ultracold molecular gases with both attractive and repulsive interactions. Moreover, our study of the interconversion between dimers and Efimov trimers shows that B2+B2-->B3+B rearrangement reactions can provide an efficient trimer formation mechanism. Our analysis of the temperature dependence of this reaction provides an interpretation of the available experimental data and sheds light on the possible experimental realization of rearrangement processes in ultracold gases.

  17. 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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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).

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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...

  19. 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...

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Separation and identification of Taxifolin 3-O-glucoside isomers from Chamaecyparis obtusa (Cupressaceae).

    PubMed

    Sakushima, Akiyo; Ohno, Kosei; Coskun, Makusut; Seki, Koh-Ichi; Ohkura, Kazue

    2002-12-01

    Taxifolin 3-O-glucoside isomers, [(2R, 3R)-, (2R, 3S)-, (2S, 3R)- and (2S, 3S)-] were isolated from leaves of Chamaecyparis obtuse (Cupressaceae). Their structures were elucidated on the basis of UV, MS, CD, 1H- and 13C-NMR spectral data, including 2D shift correlation. It was found that the compounds could be distinguished by the use of 1H- and 13C-NMR spectral data.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  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. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  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. 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

  5. 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.

  6. 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

  7. 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.

  8. 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.

  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. 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.

  11. 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

  12. 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.

  13. 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

  14. 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

  15. 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.

  16. 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

  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. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  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. 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.

  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. 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

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. 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).

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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%).

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  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. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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).

  14. 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.

  15. 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

  16. Assembly of Drosophila centromeric nucleosomes requires CID dimerization.

    PubMed

    Zhang, Weiguo; Colmenares, Serafin U; Karpen, Gary H

    2012-01-27

    Centromeres are essential chromosomal regions required for kinetochore assembly and chromosome segregation. The composition and organization of centromeric nucleosomes containing the essential histone H3 variant CENP-A (CID in Drosophila) is a fundamental, unresolved issue. Using immunoprecipitation of CID mononucleosomes and cysteine crosslinking, we demonstrate that centromeric nucleosomes contain CID dimers in vivo. Furthermore, CID dimerization and centromeric targeting require a residue implicated in formation of the four-helix bundle, which mediates intranucleosomal H3 dimerization and nucleosome integrity. Taken together, our findings suggest that CID nucleosomes are octameric in vivo and that CID dimerization is essential for correct centromere assembly.

  17. Assembly of Drosophila Centromeric Nucleosomes Requires CID Dimerization

    PubMed Central

    Zhang, Weiguo; Colmenares, Serafin U.; Karpen, Gary H.

    2012-01-01

    SUMMARY Centromeres are essential chromosomal regions required for kinetochore assembly and chromosome segregation. The composition and organization of centromeric nucleosomes containing the essential histone H3 variant CENP-A (CID in Drosophila) is a fundamental, unresolved issue. Using immunoprecipitation of CID mononucleosomes and cysteine crosslinking, we demonstrate that centromeric nucleosomes contain CID dimers in vivo. Furthermore, CID dimerization and centromeric targeting require a residue implicated in formation of the four helix bundle, which mediates intra-nucleosomal H3 dimerization and nucleosome integrity. Taken together, our findings suggest that CID nucleosomes are octameric in vivo and that CID dimerization is essential for correct centromere assembly. PMID:22209075

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. 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

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Internal structure of nanoparticle dimers linked by DNA.

    PubMed

    Chi, Cheng; Vargas-Lara, Fernando; Tkachenko, Alexei V; Starr, Francis W; Gang, Oleg

    2012-08-28

    We construct nanoparticle dimers linked by DNA. These dimers are basic units in a possible multiscale, hierarchical assembly and serve as a model system to understand DNA-mediated interactions, especially in the nontrivial regime when the nanoparticle and DNA are comparable in their sizes. We examine the structure of nanoparticle dimers in detail by a combination of scattering experiments and molecular simulations. We find that, for a given DNA length, the interparticle separation within the dimer is controlled primarily by the number of linking DNA. We summarize our findings in a simple model that captures the interplay of the number of DNA bridges, their length, the particle's curvature, and the excluded volume effects. We demonstrate the applicability of the model to our results, without any free parameters. As a consequence, the increase of dimer separation with increasing temperature can be understood as a result of changing the number of connecting DNA.

  17. [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

  18. 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.

  19. 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.

  20. Isolation, identification and stability of acylated derivatives of apigenin 7-O-glucoside from chamomile (Chamomilla recutita [L.] Rauschert).

    PubMed

    Svehliková, Vanda; Bennett, Richard N; Mellon, Fred A; Needs, Paul W; Piacente, Sonia; Kroon, Paul A; Bao, Yongping

    2004-08-01

    The major flavonoids in the white florets of chamomile (Chamomilla recutita [L.] Rauschert) were rapidly purified using a combination of polyamide solid-phase extraction and preparative HPLC. From the combined LC/MS, LC/MS/MS, and NMR data the apigenin glucosides were identified as apigenin 7-O-glucoside (Ap-7-Glc), Ap-7-(6"-malonyl-Glc), Ap-7-(6"-acetyl-Glc), Ap-7-(6"-caffeoyl-Glc), Ap-7-(4"-acetyl-Glc), Ap-7-(4"-acetyl,6"-malonyl-Glc), and a partially characterised apigenin-7-(mono-acetyl/mono-malonylglucoside) isomer. Malonyl and caffeoyl derivatives of Ap-7-Glc have not previously been identified in chamomile. The two mono-acetyl/mono-malonyl flavonoids have not previously been reported in any plant species. These acylated glucosides are unstable and degrade to form acetylated compounds or Ap-7-Glc. The degradation products formed are dependent on the extraction and storage conditions, i.e. temperature, pH and solvent.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. 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.

  9. 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

  10. 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.

  11. [A new monoterpenoid glucoside from the twigs of Chamaecyparis obtusa var. breviramea f. crippsii].

    PubMed

    Xu, Jian; Zhang, Yu-Mei; Chen, Ke-Li; Tan, Ning-Hua; Liu, Yi-Mei

    2012-09-01

    To investigate the chemical constituents of Chamaecyparis obtusa var. breviramea f. crippsii, various column chromatography and spectroscopic methods were used for the isolation and elucidation of compounds. One new monoterpenoid glucoside, (4S)-4-isopropylcyclohex-l-enecarboxylic acid 4-O-beta-D-glucopyranoside (1), together with five known compounds, (4R)-p-menth-l-ene-7, 8-diol 7-O-beta-D-glucopyranoside (2), skimmin (3), 7-[[6-O-(6-deoxy-alpha-L-mannopyranosyl)-beta-D-glucopyranosyl]oxy]-2H-1-benzopyran-2-one (4), stigmast-4-en-3-one (5) and 1, 4-benzenedicarboxylic acid 1-butyl-4-(2-methylpropyl) ester (6) were isolated and identified from the twigs of this plant. All compounds were isolated from this plant for the first time. The methanol extract of this plant showed cytotoxicity on cancer cell lines A549, BGC-823, Du145 and MDA-MB-231 with IC50 values of 0.94, 1.07, 0.95 and 0.96 microg x mL(-1), respectively. Yet, compounds 1, 2 and 3 showed no cytotoxicity on cancer cell lines HeLa, BGC-823 and A549.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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%).

  19. 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.

  20. 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.

  1. 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.

  2. [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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  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. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. [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.

  10. 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.

  11. 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.

  12. 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

  13. Anomalous atmospheric absorption spectra due to water dimer

    NASA Astrophysics Data System (ADS)

    Cai, Peipei; Zhang, Hansheng; Shen, Shanxiong; Cheng, I.-Shan

    1986-11-01

    The anomalous atmospheric absorption spectra in the window wavelength region of 8-14 microns have been suggested due to the water dimer. Based on laboratory measurements, water continuum CO2 laser absorption spectra and a resonance absorption line due to the weak local wave vapor pure rotational transition have been reported. The equilibrium concentration of water dimers in the atmosphere, the electronic binding energy and the theoretical calculations for absorption attenuation have been obtained in agreement with published data.

  14. 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.

  15. 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%.

  16. 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

  17. 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.

  18. 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

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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).

  10. 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

  11. 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.

  12. 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.

  13. Products and mechanism of acene dimerization. A computational study.

    PubMed

    Zade, Sanjio S; Zamoshchik, Natalia; Reddy, A Ravikumar; Fridman-Marueli, Galit; Sheberla, Dennis; Bendikov, Michael

    2011-07-20

    The high reactivity of acenes can reduce their potential applications in the field of molecular electronics. Although pentacene is an important material for use in organic field-effect transistors because of its high charge mobility, its reactivity is a major disadvantage hindering the development of pentacene applications. In this study, several reaction pathways for the thermal dimerization of acenes were considered computationally. The formation of acene dimers via a central benzene ring and the formation of acene-based polymers were found to be the preferred pathways, depending on the length of the monomer. Interestingly, starting from hexacene, acene dimers are thermodynamically disfavored products, and the reaction pathway is predicted to proceed instead via a double cycloaddition reaction (polymerization) to yield acene-based polymers. A concerted asynchronous reaction mechanism was found for benzene and naphthalene dimerization, while a stepwise biradical mechanism was predicted for the dimerization of anthracene, pentacene, and heptacene. The biradical mechanism for dimerization of anthracene and pentacene proceeds via syn or anti transition states and biradical minima through stepwise biradical pathways, while dimerization of heptacene proceeds via asynchronous ring closure of the complex formed by two heptacene molecules. The activation barriers for thermal dimerization decrease rapidly with increasing acene chain length and are calculated (at M06-2X/6-31G(d)+ZPVE) to be 77.9, 57.1, 33.3, -0.3, and -12.1 kcal/mol vs two isolated acene molecules for benzene, naphthalene, anthracene, pentacene, and heptacene, respectively. If activation energy is calculated vs the initially formed complex of two acene molecules, then the calculated barriers are 80.5, 63.2, 43.7, 16.7, and 12.3 kcal/mol. Dimerization is exothermic from anthracene onward, but it is endothermic at the terminal rings, even for heptacene. Phenyl substitution at the most reactive meso

  14. 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.

  15. Physico-chemical properties of molten dimer ascorbate oxidase.

    PubMed

    Nicolai, Eleonora; Di Venere, Almerinda; Rosato, Nicola; Rossi, Antonello; Finazzi Agro', Alessandro; Mei, Giampiero

    2006-11-01

    The possible presence of dimeric unfolding intermediates might offer a clue to understanding the relationship between tertiary and quaternary structure formation in dimers. Ascorbate oxidase is a large dimeric enzyme that displays such an intermediate along its unfolding pathway. In this study the combined effect of high pressure and denaturing agents gave new insight on this intermediate and on the mechanism of its formation. The transition from native dimer to the dimeric intermediate is characterized by the release of copper ions forming the tri-nuclear copper center located at the interface between domain 2 and 3 of each subunit. This transition, which is pH-dependent, is accompanied by a decrease in volume, probably associated to electrostriction due to the loosening of intra-subunit electrostatic interactions. The dimeric species is present even at 3 x 10(8) Pa, providing evidence that mechanically or chemically induced unfolding lead to a similar intermediate state. Instead, dissociation occurs with an extremely large and negative volume change (DeltaV approximately -200 mL.mol(-1)) by pressurization in the presence of moderate amounts of denaturant. This volume change can be ascribed to the elimination of voids at the subunit interface. Furthermore, the combination of guanidine and high pressure uncovers the presence of a marginally stable (DeltaG approximately 2 kcal.mol(-1)) monomeric species (which was not observed in previous equilibrium unfolding measurements) that might be populated in the early folding steps of ascorbate oxidase. These findings provide new aspects of the protein folding pathway, further supporting the important role of quaternary interactions in the folding strategy of large dimeric enzymes.

  16. Theoretical studies on the dimerization of substituted paraphenylenediamine radical cations

    NASA Astrophysics Data System (ADS)

    Punyain, Kraiwan; Kelterer, Anne-Marie; Grampp, Günter

    2011-12-01

    Organic radical cations form dicationic dimers in solution, observed experimentally as diamagnetic species in temperature-dependent EPR and low temperature UV/Vis spectroscopy. Dimerization of paraphenylenediamine, N,N-dimethyl-paraphenylenediamine and 2,3,5,6-tetramethyl-paraphenylenediamine radical cation in ethanol/diethylether mixture was investigated theoretically according to geometry, energetics and UV/Vis spectroscopy. Density Functional Theory including dispersion correction describes stable dimers after geometry optimization with conductor-like screening model of solvation and inclusion of the counter-ion. Energy corrections were done on double-hybrid Density Functional Theory with perturbative second-order correlation (B2PLYP-D) including basis set superposition error (BSSE), and multireference Møller-Plesset second-order perturbation theory method (MRMP2) based on complete active space method (CASSCF(2,2)) single point calculation, respectively. All three dication π-dimers exhibit long multicenter π-bonds around 2.9 ± 0.1 Å with strongly interacting orbitals. Substitution with methyl groups does not influence the dimerization process substantially. Dispersion interaction and electrostatic attraction from counter-ion play an important role to stabilize the dication dimers in solution. Dispersion-corrected double hybrid functional B2PLYP-D and CASSCF(2,2) can describe the interaction energetics properly. Vertical excitations were computed with Tamm-Dancoff approximation for time-dependent Density Functional Theory (TDA-DFT) at the B3LYP level with the cc-pVTZ basis set including ethanol solvent molecules explicitly. A strong interaction of the counter-ion and the solvent ethanol with the monomeric species is observed, whereas in the dimers the strong interaction of both radical cation species is the dominating factor for the additional peak in UV/Vis spectra.

  17. Dimerization in Highly Concentrated Solutions of Phosphoimidazolide Activated Monomucleotides

    NASA Astrophysics Data System (ADS)

    Kanavarioti, Anastassia

    1997-08-01

    Phosphoimidazolide activated ribomononucleotides (*pN) are useful substrates for the non-enzymatic synthesis of polynucleotides. However, dilute neutral aqueous solutions of *pN typically yield small amounts of dimers and traces of polymers; most of *pN hydrolyzes to yield nucleoside 5'-monophosphate. Here we report the self-condensation of nucleoside 5'-phosphate 2-methylimidazolide (2-MeImpN with N = cytidine, uridine or guanosine) in the presence of Mg2+ in concentrated solutions, such as might have been found in an evaporating lagoon on prebiotic Earth. The product distribution indicates that oligomerization is favored at the expense of hydrolysis. At 1.0 M, 2-MeImpU and 2-MeImpC produce about 65% of oligomers including 4% of the 3',5'-linked dimer. Examination of the product distribution of the three isomeric dimers in a self-condensation allows identification of reaction pathways that lead to dimer formation. Condensations in a concentrated mixture of all three nucleotides (U,C,G mixtures) is made possible by the enhanced solubility of 2-MeImpG in such mixtures. Although percent yield of internucleotide linked dimers is enhanced as a function of initial monomer concentration, pyrophosphate dimer yields remain practically unchanged at about 20% for 2-MeImpU, 16% for 2-MeImpC and 25% of the total pyrophosphate in the U,C,G mixtures. The efficiency by which oligomers are produced in these concentrated solutions makes the evaporating lagoon scenario a potentially interesting medium for the prebiotic synthesis of dimers and short RNAs.

  18. Integrability and conformal data of the dimer model

    NASA Astrophysics Data System (ADS)

    Morin-Duchesne, Alexi; Rasmussen, Jørgen; Ruelle, Philippe

    2016-04-01

    The central charge of the dimer model on the square lattice is still being debated in the literature. In this paper, we provide evidence supporting the consistency of a c=-2 description. Using Lieb’s transfer matrix and its description in terms of the Temperley-Lieb algebra {{TL}}n at β =0, we provide a new solution of the dimer model in terms of the model of critical dense polymers on a tilted lattice and offer an understanding of the lattice integrability of the dimer model. The dimer transfer matrix is analyzed in the scaling limit, and the result for {L}0-\\frac{c}{24} is expressed in terms of fermions. Higher Virasoro modes are likewise constructed as limits of elements of {{TL}}n and are found to yield a c=-2 realization of the Virasoro algebra, familiar from fermionic bc ghost systems. In this realization, the dimer Fock spaces are shown to decompose, as Virasoro modules, into direct sums of Feigin-Fuchs modules, themselves exhibiting reducible yet indecomposable structures. In the scaling limit, the eigenvalues of the lattice integrals of motion are found to agree exactly with those of the c=-2 conformal integrals of motion. Consistent with the expression for {L}0-\\frac{c}{24} obtained from the transfer matrix, we also construct higher Virasoro modes with c = 1 and find that the dimer Fock space is completely reducible under their action. However, the transfer matrix is found not to be a generating function for the c = 1 integrals of motion. Although this indicates that Lieb’s transfer matrix description is incompatible with the c = 1 interpretation, it does not rule out the existence of an alternative, c = 1 compatible, transfer matrix description of the dimer model.

  19. Dimerization in Highly Concentrated Solutions of Phosphoimidazolide Activated Mononucleotides

    NASA Technical Reports Server (NTRS)

    Kanavarioti, Anastassia

    1997-01-01

    Phosphoimidazolide activated ribomononucleotides (*pN) are useful substrates for the non-enzymatic synthesis of polynucleotides. However, dilute neutral aqueous solutions of *pN typically yield small amounts of dimers and traces of polymers; most of *pN hydrolyzes to yield nucleoside 5'-monophosphate. Here we report the self-condensation of nucleoside 5'-phosphate 2- methylimidazolide (2-MeImpN with N = cytidine, uridine or guanosine) in the presence of Mg2(+) in concentrated solutions, such as might have been found in an evaporating lagoon on prebiotic Earth. The product distribution indicates that oligomerization is favored at the expense of hydrolysis. At 1.0 M, 2-MelmpU and 2-MelmpC produce about 65% of oligomers including 4% of the 3',5'-Iinked dimer. Examination of the product distribution of the three isomeric dimers in a self-condensation allows identification of reaction pathways that lead to dimer formation. Condensations in a concentrated mixture of all three nucleotides (U,C,G mixtures) is made possible by the enhanced solubility of 2-MeImpG in such mixtures. Although percent yield of intemucleotide linked dimers is enhanced as a function of initial monomer concentration, pyrophosphate dimer yields remain practically unchanged at about 20% for 2-MelmpU, 16% for 2-MeImpC and 25% of the total pyrophosphate in the U,C,G mixtures. The efficiency by which oligomers are produced in these concentrated solutions makes the evaporating lagoon scenario a potentially interesting medium for the prebiotic synthesis of dimers and short RNAs.

  20. 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

  1. 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.

  2. 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

  3. 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.

  4. [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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. Long-term cultured hairy roots of chicory-a rich source of hydroxycinnamates and 8-deoxylactucin glucoside.

    PubMed

    Malarz, Janusz; Stojakowska, Anna; Kisiel, Wanda

    2013-12-01

    A 12-year-old hairy root culture of Cichorium intybus L., a callus culture of the plant as well as roots and leaves of a wild plant of chicory, and roots of two C. intybus L. var. sativum cultivars were examined in respect of their hydroxycinnamate and sesquiterpene lactone compositions and contents. Total phenolics and diphenylpicrylhydrazyl radical scavenging activity of the examined plant tissues were also analyzed. The most active in radical scavenging were extracts from the hairy roots and leaves of chicory. 3,5-Dicaffeoylquinic acid was the major antioxidant present in the hairy roots. Its content in the root biomass reached 5.5 %, calculated on a dry weight basis. 8-Deoxylactucin glucoside (crepidiaside A) was the major sesquiterpene lactone in the hairy roots. Its content reached 1.4 %, calculated on a dry weight basis, and was nearly two orders of magnitude higher than that in the roots of wild chicory plant. The glucosidic derivative of 8-deoxylactucin constituted over 85 % of the total sesquiterpene lactone content in the long-term cultured hairy roots of chicory. Aglycone of this compound was reported to possess anti-inflammatory activity. The qualitative and quantitative analyses of hydroxycinnamates in callus and hairy root cultures of C. intybus were undertaken for the first time.

  11. Visualization of Myc/Max/Mad family dimers and the competition for dimerization in living cells.

    PubMed

    Grinberg, Asya V; Hu, Chang-Deng; Kerppola, Tom K

    2004-05-01

    Myc and Mad family proteins play opposing roles in the control of cell growth and proliferation. We have visualized the subcellular locations of complexes formed by Myc/Max/Mad family proteins using bimolecular fluorescence complementation (BiFC) analysis. Max was recruited to different subnuclear locations by interactions with Myc versus Mad family members. Complexes formed by Max with Mxi1, Mad3, or Mad4 were enriched in nuclear foci, whereas complexes formed with Myc were more uniformly distributed in the nucleoplasm. Mad4 was localized to the cytoplasm when it was expressed separately, and Mad4 was recruited to the nucleus through dimerization with Max. The cytoplasmic localization of Mad4 was determined by a CRM1-dependent nuclear export signal located near the amino terminus. We compared the relative efficiencies of complex formation among Myc, Max, and Mad family proteins in living cells using multicolor BiFC analysis. Max formed heterodimers with the basic helix-loop-helix leucine zipper (bHLHZIP) domain of Myc (bMyc) more efficiently than it formed homodimers. Replacement of two amino acid residues in the leucine zipper of Max reversed the relative efficiencies of homo- and heterodimerization in cells. Surprisingly, Mad3 formed complexes with Max less efficiently than bMyc, whereas Mad4 formed complexes with Max more efficiently than bMyc. The distinct subcellular locations and the differences between the efficiencies of dimerization with Max indicate that Mad3 and Mad4 are likely to modulate transcription activation by Myc at least in part through distinct mechanisms.

  12. Visualization of Myc/Max/Mad Family Dimers and the Competition for Dimerization in Living Cells†

    PubMed Central

    Grinberg, Asya V.; Hu, Chang-Deng; Kerppola, Tom K.

    2004-01-01

    Myc and Mad family proteins play opposing roles in the control of cell growth and proliferation. We have visualized the subcellular locations of complexes formed by Myc/Max/Mad family proteins using bimolecular fluorescence complementation (BiFC) analysis. Max was recruited to different subnuclear locations by interactions with Myc versus Mad family members. Complexes formed by Max with Mxi1, Mad3, or Mad4 were enriched in nuclear foci, whereas complexes formed with Myc were more uniformly distributed in the nucleoplasm. Mad4 was localized to the cytoplasm when it was expressed separately, and Mad4 was recruited to the nucleus through dimerization with Max. The cytoplasmic localization of Mad4 was determined by a CRM1-dependent nuclear export signal located near the amino terminus. We compared the relative efficiencies of complex formation among Myc, Max, and Mad family proteins in living cells using multicolor BiFC analysis. Max formed heterodimers with the basic helix-loop-helix leucine zipper (bHLHZIP) domain of Myc (bMyc) more efficiently than it formed homodimers. Replacement of two amino acid residues in the leucine zipper of Max reversed the relative efficiencies of homo- and heterodimerization in cells. Surprisingly, Mad3 formed complexes with Max less efficiently than bMyc, whereas Mad4 formed complexes with Max more efficiently than bMyc. The distinct subcellular locations and the differences between the efficiencies of dimerization with Max indicate that Mad3 and Mad4 are likely to modulate transcription activation by Myc at least in part through distinct mechanisms. PMID:15121849

  13. Synthesis and Applications of Non-spherical Dimer Colloids

    NASA Astrophysics Data System (ADS)

    Yoon, Kisun

    Colloids are promising building blocks in material synthesis because of their controllability of size and surface properties. The synthesis of chemically and/or geometrically anisotropic colloidal particles has received attentions with the expectation of building blocks for complex structures. However, the synthesis of anisotropic colloidal particles is by far more difficult than the synthesis of spherical colloidal particles. Lack of monodispersity and productivity of many anisotropic particles often limits their applications as a building block for complex structures. Thus, it is highly desirable to develop methods which can produce a large amount of monodisperse non-spherical particles with controllable asymmetric surface properties. This dissertation details the work for developing such a method. The major result of this dissertation is a synthetic method to produce monodisperse non-spherical colloids with anisotropic surface property in a large quantity. The anisotropic colloid, which we call it as Dimer particle, has two fused lobes like a dumbbell and each lobe's size can be independently controlled. We present a novel method to synthesize sub-micron size Dimer particles. This method can produce a large amount of submicron-sized Dimer particles with good monodispersity and well-controlled shape. Submicron-sized Dimer particles have been highly desired since they can be used as a building block for self assembly using Brownian motion, colloidal surfactant for Pickering emulsion, and photonic materials. To fully take advantage of the anisotropy of the particles, we develop a facile method to tailor the surface property of each lobe independently by asymmetrically coating the particles with gold nanoparticles. This method doesn't need the arrangement of particles onto any type of interfaces. Asymmetric coating of gold nanoparticles can be carried out simply by mixing Dimer particles with gold nanoparticles. The formation mechanism of the submicron-sized Dimer

  14. Hydrogenated fullerenes dimer, peanut and capsule: An atomic comparison

    NASA Astrophysics Data System (ADS)

    EL-Barbary, A. A.

    2016-04-01

    Hydrogenated fullerenes are detected in the Universe in space but their identification is still unsolved task. Therefore, this paper provides useful information about hydrogenated fullerenes (dimer, peanut and capsule) using DFT method at the B3LYP/6-31G(d) level of theory. The stability, geometric structures, hydrogen adsorption energies and NMR chemical shifts are calculated. The results show that the energy of most stable isomer of C118 dimer is lower than the energies sum of C60 and C58 cages by 1.77 eV and the energy per carbon atom of C144 capsule is more stable than C60 cage by 126.98 meV. Also, endohedral Ti-doped C118 dimer and C128 peanut are found to be most stable structures than exohedral Ti-doped C118 dimer and C128 peanut by 2.19 eV/Ti and 3.52 eV/Ti, respectively. The hydrogenation process is found to be enhanced (especially at the caps) for endohedral Ti-doped C118 dimer and C128 peanut through electronic surface modifications. The most active hydrogenation sites are selected and it is found that the most stable hydrogenation sites are Houts1 and Houts3 for fullerenes and endohedral Ti-doped fullerenes, respectively.

  15. Effects of Dimerization of Serratia marcescens Endonuclease on Water Dynamics.

    SciTech Connect

    Chen, Chuanying; Beck, Brian W.; Krause, Kurt; Weksberg, Tiffany E.; Pettitt, Bernard M.

    2007-02-15

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. The dynamics and structure of Serratia marcescens endonuclease and its neighboring solvent are investigated by molecular dynamics (MD). Comparisons are made with structural and biochemical experiments. The dimer form is physiologic and functions more processively than the monomer. We previously found a channel formed by connected clusters of waters from the active site to the dimer interface. Here, we show that dimerization clearly changes correlations in the water structure and dynamics in the active site not seen in the monomer. Our results indicate that water at the active sites of the dimer is less affected compared with bulk solvent than in the monomer where it has much slower characteristic relaxation times. Given that water is a required participant in the reaction, this gives a clear advantage to dimerization in the absence of an apparent ability to use both active sites simultaneously.

  16. Highly stable tetrathiafulvalene radical dimers in [3]catenanes

    SciTech Connect

    Spruell, Jason M.; Coskun, Ali; Friedman, Douglas C.; Forgan, Ross S.; Sarjeant, Amy A.; Trabolsi, Ali; Fahrenbach, Albert C.; Barin, Gokhan; Paxton, Walter F.; Dey, Sanjeev K.; Olson, Mark A.; Benítez, Diego; Tkatchouk, Ekaterina; Colvin, Michael T.; Carmielli, Raanan; Caldwell, Stuart T.; Rosair, Georgina M.; Hewage, Shanika Gunatilaka; Duclairoir, Florence; Seymour, Jennifer L.; Slawin, Alexandra M.Z.; Goddard, III, William A.; Wasielewski, Michael R.; Cooke, Graeme; Stoddart, J. Fraser

    2010-12-03

    Two [3]catenane 'molecular flasks' have been designed to create stabilized, redox-controlled tetrathiafulvalene (TTF) dimers, enabling their spectrophotometric and structural properties to be probed in detail. The mechanically interlocked framework of the [3]catenanes creates the ideal arrangement and ultrahigh local concentration for the encircled TTF units to form stable dimers associated with their discrete oxidation states. These dimerization events represent an affinity umpolung, wherein the inversion in electronic affinity replaces the traditional TTF-bipyridinium interaction, which is over-ridden by stabilizing mixed-valence (TTF){sub 2}{sup {sm_bullet}+} and radical-cation (TTF{sup {sm_bullet}+}){sub 2} states inside the 'molecular flasks.' The experimental data, collected in the solid state as well as in solution under ambient conditions, together with supporting quantum mechanical calculations, are consistent with the formation of stabilized paramagnetic mixed-valence dimers, and then diamagnetic radical-cation dimers following subsequent one-electron oxidations of the [3]catenanes.

  17. Altered Dimer Interface Decreases Stability in an Amyloidogenic Protein

    SciTech Connect

    Baden, Elizabeth M.; Owen, Barbara A.L.; Peterson, Francis C.; Volkman, Brian F.; Ramirez-Alvarado, Marina; Thompson, James R.

    2008-07-21

    Amyloidoses are devastating and currently incurable diseases in which the process of amyloid formation causes fatal cellular and organ damage. The molecular mechanisms underlying amyloidoses are not well known. In this study, we address the structural basis of immunoglobulin light chain amyloidosis, which results from deposition of light chains produced by clonal plasma cells. We compare light chain amyloidosis protein AL-09 to its wild-type counterpart, the kl O18/O8 light chain germline. Crystallographic studies indicate that both proteins form dimers. However, AL-09 has an altered dimer interface that is rotated 90 degrees from the kl O18/O8 dimer interface. The three non-conservative mutations in AL-09 are located within the dimer interface, consistent with their role in the decreased stability of this amyloidogenic protein. Moreover, AL-09 forms amyloid fibrils more quickly than kl O18/O8 in vitro. These results support the notion that the increased stability of the monomer and delayed fibril formation, together with a properly formed dimer, may be protective against amyloidogenesis. This could open a new direction into rational drug design for amyloidogenic proteins.

  18. Structure determination and conformation analysis of symmetrical dimers.

    PubMed

    Buevich, Alexei V; Chan, Tze-Ming; Wang, C H; McPhail, Andrew T; Ganguly, A K

    2005-03-01

    Conformational and stereochemical analysis of six new symmetrical dimers was performed using proton-proton vicinal coupling measured from (1)H NMR and (13)C satellites of (1)H NMR signals, natural abundance (13)C-edited nuclear overhauser effect (NOE) experiments, comprehensive NOE analysis and molecular modeling. The (13)C satellite analysis and (13)C-edited NOE experiments were carried out to extract spectral information between equivalent protons. Molecular modeling was applied for estimations of three-dimensional parameters of the studied dimers, which were subsequently used to generate a set of theoretical NOE for each possible conformation. The J-coupling, (13)C-edited NOE and quantitative NOE analyses showed the predominance of gauche conformation for three dimers, whereas a mixture of gauche and anti conformations (45:55) for three other dimers was established by quantitative NOE analysis. X-ray crystallographic study confirmed the stereochemistry of one of the dimers and revealed a discrepancy in conformation stability between liquid and solid states.

  19. Secreted CXCL12 (SDF-1) Forms Dimers under Physiologic Conditions

    PubMed Central

    Ray, Paramita; Lewin, Sarah A.; Mihalko, Laura Anne; Lesher-Perez, Sasha Cai; Takayama, Shuichi; Luker, Kathryn E.; Luker, Gary D.

    2015-01-01

    Chemokine CXCL12 signaling through receptors CXCR4 and CXCR7 has essential functions in development and underlies diseases including cancer, atherosclerosis, and autoimmunity. Chemokines may form homodimers that regulate receptor binding and signaling, but previous studies with synthetic CXCL12 have produced conflicting evidence for homodimerization. We used bioluminescence imaging with Gaussia luciferase fusions to investigate dimerization of CXCL12 secreted from mammalian cells. By column chromatography and Gaussia luciferase complementation, we established that CXCL12 was secreted from mammalian cells as both monomers and dimers. Secreted CXCL12 also formed homodimers in the extracellular space. Monomeric CXCL12 preferentially activated CXCR4 signaling through Gαi and AKT, while dimeric CXCL12 more effectively promoted recruitment of β-arrestin 2 to CXCR4 and chemotaxis of CXCR4-expressing breast cancer cells. We also showed that CXCR7 preferentially sequestered monomeric CXCL12 from the extracellular space and had minimal effects on dimeric CXCL12 in cell-based assays and an orthotopic tumor xenograft model of human breast cancer. These studies establish that CXCL12 secreted from mammalian cells forms homodimers under physiologic conditions. Since monomeric and dimeric CXCL12 have distinct effects on cell signaling and function, our results have important implications for ongoing efforts to target CXCL12 pathways for therapy. PMID:22142194

  20. Palladium dimers adsorbed on graphene: A DFT study

    SciTech Connect

    Kaur, Gagandeep; Gupta, Shuchi; Dharamvir, Keya

    2015-05-15

    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 (Pd{sub 2}) on graphene using SIESTA package, in the generalized gradient approximation (GGA). The adsorption energy, geometry, and charge transfer of Pd{sub 2}-graphene system are calculated. Both horizontal and vertical orientations of Pd{sub 2} 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.

  1. Resveratrol Metabolites Modify Adipokine Expression and Secretion in 3T3-L1 Pre-Adipocytes and Mature Adipocytes

    PubMed Central

    Eseberri, Itziar; Lasa, Arrate; Churruca, Itziar; Portillo, María P.

    2013-01-01

    Objective Due to the low bioavailability of resveratrol, determining whether its metabolites exert any beneficial effect is an interesting issue. Methods 3T3-L1 maturing pre-adipocytes were treated during differentiation with 25 µM of resveratrol or with its metabolites and 3T3-L1 mature adipocytes were treated for 24 hours with 10 µM resveratrol or its metabolites. The gene expression of adiponectin, leptin, visfatin and apelin was assessed by Real Time RT-PCR and their concentration in the incubation medium was quantified by ELISA. Results Resveratrol reduced mRNA levels of leptin and increased those of adiponectin. It induced the same changes in leptin secretion. Trans-resveratrol-3-O-glucuronide and trans-resveratrol-4′-O-glucuronide increased apelin and visfatin mRNA levels. Trans-resveratrol-3-O-sulfate reduced leptin mRNA levels and increased those of apelin and visfatin. Conclusions The present study shows for the first time that resveratrol metabolites have a regulatory effect on adipokine expression and secretion. Since resveratrol has been reported to reduce body-fat accumulation and to improve insulin sensitivity, and considering that these effects are mediated in part by changes in the analyzed adipokines, it may be proposed that resveratrol metabolites play a part in these beneficial effects of resveratrol. PMID:23717508

  2. Revisiting the putative TCR Cα dimerization model through structural analysis.

    PubMed

    Wang, Jia-Huai; Reinherz, Ellis L

    2013-01-01

    Despite major advances in T cell receptor (TCR) biology and structure, how peptide-MHC complex (pMHC) ligands trigger αβ TCR activation remains unresolved. Two views exist. One model postulates that monomeric TCR-pMHC ligation events are sufficient while a second proposes that TCR-TCR dimerization in cis via Cα domain interaction plus pMHC binding is critical. We scrutinized 22 known TCR/pMHC complex crystal structures, and did not find any predicted molecular Cα-Cα contacts in these crystals that would allow for physiological TCR dimerization. Moreover, the presence of conserved glycan adducts on the outer face of the Cα domain preclude the hypothesized TCR dimerization through the Cα domain. Observed functional consequences of Cα mutations are likely indirect, with TCR microclusters at the immunological synapse driven by TCR transmembrane/cytoplasmic interactions via signaling molecules, scaffold proteins, and/or cytoskeletal elements.

  3. Polarization to the field enhancement by a gold dimer

    NASA Astrophysics Data System (ADS)

    Hong, Xin; Jin, Zheng

    2016-11-01

    Due to the effect of plasmonic coupling, gold nanoparticle dimers have been paid more attentions in bio-imaging. The coupling effect existing at the gap between a closely linked particle pair can make the local field strongly enhanced and in which the angle between the excitation polarization and the dimer axis plays a dominant role. We calculated the amplitude distribution under a highly focused illumination objective. The simulation results show that for such a model, 45 degrees between the excitation polarization and the dimer axis can produce an optimum signal. The enhancement thus obtained is 10.78 fold while the variation between peak-peak can reach 6.59 fold compared to a single plasmoic particle during the rotation of the polarization.

  4. Optofluidic taming of a colloidal dimer with a silicon nanocavity

    SciTech Connect

    Pin, C.; Renaut, C.; Cluzel, B. Fornel, F. de; Peyrade, D.; Picard, E.; Hadji, E.

    2014-10-27

    We report here the optical trapping of a heterogeneous colloidal dimer above a photonic crystal nanocavity used as an on-chip optical tweezer. The trapped dimer consists of a cluster of two dielectric microbeads of different sizes linked by van der Waals forces. The smallest bead, 1 μm in diameter, is observed to be preferentially trapped by the nanotweezer, leaving the second bead untrapped. The rotational nature of the trapped dimer Brownian motion is first evidenced. Then, in the presence of a fluid flow, control of its orientation and rotation is achieved. The whole system is found to show high rotational degrees of freedom, thereby acting as an effective flow-sensitive microscopic optical ball joint.

  5. D-dimer is elevated in acute aortic dissection.

    PubMed

    Martin, Thomas; Shariq, Sohail

    2010-08-31

    This case illustrates that d-dimer is elevated in patients with acute aortic dissection. A 49-year-old woman presented with central, crushing chest pain exacerbated on inspiration. The chest pain was associated with right-leg numbness and pain, although peripheral pulses and blood pressures were normal. Routine bloods demonstrated an elevated d-dimer with a normal ECG and chest x-ray radiograph. A differential diagnosis of pulmonary embolism and acute aortic dissection was made. CT-angiogram showed type B aortic dissection. This case report highlights the mounting evidence that d-dimer is elevated in practically all incidents of aortic dissection and could be useful as a negative predictive marker.

  6. An exploration of the ozone dimer potential energy surface

    SciTech Connect

    Azofra, Luis Miguel; Alkorta, Ibon; Scheiner, Steve

    2014-06-28

    The (O{sub 3}){sub 2} dimer potential energy surface is thoroughly explored at the ab initio CCSD(T) computational level. Five minima are characterized with binding energies between 0.35 and 2.24 kcal/mol. The most stable may be characterized as slipped parallel, with the two O{sub 3} monomers situated in parallel planes. Partitioning of the interaction energy points to dispersion and exchange as the prime contributors to the stability, with varying contributions from electrostatic energy, which is repulsive in one case. Atoms in Molecules analysis of the wavefunction presents specific O⋯O bonding interactions, whose number is related to the overall stability of each dimer. All internal vibrational frequencies are shifted to the red by dimerization, particularly the antisymmetric stretching mode whose shift is as high as 111 cm{sup −1}. In addition to the five minima, 11 higher-order stationary points are identified.

  7. Epoxidation of propylene dimers and isomerization of mixtures obtained

    SciTech Connect

    Dobrev, D.M.; Kurtev, K.S.

    1988-05-10

    Mixtures of hexenes are obtained in the dimerization of propylene on a Ziegler catalyst. By the epoxidation of this mixture by organic peroxides, followed by isomerization of the oxides, C/sub 6/ ketones, which are used as solvents, can be obtained. The hexenes were obtained by dimerization of propylene in the presence of a Ni(C/sub 5/H/sub 7/O/sub 2/)/sub 2/-P(C/sub 6/H/sub 5/)/sub 3/-(C/sub 3/H/sub 5/)/sub 2/AlCl catalytic system. The epoxidation was carried with technical grade isopropylbenzyl hydroperoxide (IPBHP). MoO/sub 2/(C/sub 5/H/sub 7/O/sub 2/)/sub 2/ was used as the catalyst. The relative rates of epoxidation of different isomers contained in the dimeric fraction, with respect to 2-methyl-1-pentene, was determined by means of competing reactions.

  8. Microwave Spectrum of the Isopropanol-Water Dimer

    NASA Astrophysics Data System (ADS)

    Mead, Griffin; Finneran, Ian A.; Carroll, Brandon; Blake, Geoffrey

    2016-06-01

    Microwave spectroscopy provides a unique opportunity to study model non-covalent interactions. Of particular interest is the hydrogen bonding of water, whose various molecular properties are influenced by both strong and weak intermolecular forces. More specifically, measuring the hydrogen bonded structures of water-alcohol dimers investigates both strong (OH ··· OH) and weak (CH ··· OH) hydrogen bond interactions. Recently, we have measured the pure rotational spectrum of the isopropanol-water dimer using chirped-pulse Fourier transform microwave spectroscopy (CP-FTMW) between 8-18 GHz. Here, we present the spectrum of this dimer and elaborate on the structure's strong and weak hydrogen bonding.

  9. Micellisation and immunoreactivities of dimeric beta-caseins.

    PubMed

    Yousefi, Reza; Gaudin, Jean-Charles; Chobert, Jean-Marc; Pourpak, Zahra; Moin, Mostafa; Moosavi-Movahedi, Ali Akbar; Haertle, Thomas

    2009-12-01

    Bovine beta-casein (beta-CN) is a highly amphiphilic micellising phospho-protein showing chaperone-like activity in vitro. Recently, existence of multiple sequential epitopes on beta-CN polypeptide chain in both hydrophilic-polar (psi) and hydrophobic-apolar domains (phi) has been evidenced. In order to clarify specific contribution of polar and apolar domains in micellisation process and in shaping immunoreactivity of beta-CN, its dimeric/bi-amphiphilic "quasi palindromic" forms covalently connected by a disulfide bond linking either N-terminal (C4 beta-CND) or C-terminal domain (C208 beta-CND) were produced and studied. Depending on the C- or N-terminal position of inserted cysteine, each dimeric beta-CN contains one polar/apolar region at the centre and two external hydrophobic/hydrophilic ends. Consequently, such casein dimers have radically different polarities/hydrophobicities on their outside surfaces. Dynamic light scattering (DLS) measurements indicate that these dimeric casein molecules form micelles of different sizes depending on arrangement of polar fragments of the beta-CN mutants in their constrained dimers. Non-aggregated dimers have different hydrodynamic diameters that could be explained by their different geometries. Measurements of fluorescence showed more hydrophobic environment of Trp residues of C208 beta-CND, while in similar experimental conditions Trp residues of C4 beta-CND and native beta-CN were more exposed to the polar medium. Both fluorescence and DLS studies showed greater propensity for micellisation of the dimeric beta-CNs, suggesting that the factors inducing the formation of micelles are stronger in the bi-amphiphilic dimers. 1-anilino-naphthalene-8-sulfonate (ANS) binding studies showed different binding of ANS by these dimers as well as different exposition of ANS binding (hydrophobic) regions in the micellar states. The differences in fluorescence resonance energy transfer (FRET) profiles of C4 beta-CND and C208 beta-CND can

  10. Fluxional σ-Bonds of the 2,5,8-Trimethylphenalenyl Dimer: Direct Observation of the Sixfold σ-Bond Shift via a π-Dimer.

    PubMed

    Uchida, Kazuyuki; Mou, Zhongyu; Kertesz, Miklos; Kubo, Takashi

    2016-04-06

    Direct evidence for σ-bond fluxionality in a phenalenyl σ-dimer was successfully obtained by a detailed investigation of the solution-state dynamics of 2,5,8-trimethylphenalenyl (TMPLY) using both experimental and theoretical approaches. TMPLY formed three diamagnetic dimers, namely, the σ-dimer (RR/SS), σ-dimer (RS), and π-dimer, which were fully characterized by (1)H NMR spectroscopy and electronic absorption measurements. The experimental findings gave the first quantitative insights into the essential preference of these competitive and unusual dimerization modes. The spectroscopic analyses suggested that the σ-dimer (RR/SS) is the most stable in terms of energy, whereas the others are metastable; the energy differences between these three isomers are less than 1 kcal mol(-1). Furthermore, the intriguing dynamics of the TMPLY dimers in the solution state were fully revealed by means of (1)H-(1)H exchange spectroscopy (EXSY) measurements and variable-temperature (1)H NMR studies. Surprisingly, the σ-dimer (RR/SS) demonstrated a sixfold σ-bond shift between the six sets of α-carbon pairs. This unusual σ-bond fluxionality is ascribed to the presence of a direct interconversion pathway between the σ-dimer (RR/SS) and the π-dimer, which was unambiguously corroborated by the EXSY measurements. The proposed mechanism of the sixfold σ-bond shift based on the experimental findings was well-supported by theoretical calculations.

  11. Covalent intermolecular interaction of the nitric oxide dimer (NO)2

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Zheng, Gui-Li; Lv, Gang; Geng, Yi-Zhao; Ji, Qing

    2015-09-01

    Covalent bonds arise from the overlap of the electronic clouds in the internucleus region, which is a pure quantum effect and cannot be obtained in any classical way. If the intermolecular interaction is of covalent character, the result from direct applications of classical simulation methods to the molecular system would be questionable. Here, we analyze the special intermolecular interaction between two NO molecules based on quantum chemical calculation. This weak intermolecular interaction, which is of covalent character, is responsible for the formation of the NO dimer, (NO)2, in its most stable conformation, a cis conformation. The natural bond orbital (NBO) analysis gives an intuitive illustration of the formation of the dimer bonding and antibonding orbitals concomitant with the breaking of the π bonds with bond order 0.5 of the monomers. The dimer bonding is counteracted by partially filling the antibonding dimer orbital and the repulsion between those fully or nearly fully occupied nonbonding dimer orbitals that make the dimer binding rather weak. The direct molecular mechanics (MM) calculation with the UFF force fields predicts a trans conformation as the most stable state, which contradicts the result of quantum mechanics (QM). The lesson from the investigation of this special system is that for the case where intermolecular interaction is of covalent character, a specific modification of the force fields of the molecular simulation method is necessary. Project supported by the National Natural Science Foundation of China (Grant Nos. 90403007 and 10975044), the Key Subject Construction Project of Hebei Provincial Universities, China, the Research Project of Hebei Education Department, China (Grant Nos. Z2012067 and Z2011133), the National Natural Science Foundation of China (Grant No. 11147103), and the Open Project Program of State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, China (Grant No. Y5

  12. Dimeric α-Cobratoxin X-ray Structure

    PubMed Central

    Osipov, Alexey V.; Rucktooa, Prakash; Kasheverov, Igor E.; Filkin, Sergey Yu.; Starkov, Vladislav G.; Andreeva, Tatyana V.; Sixma, Titia K.; Bertrand, Daniel; Utkin, Yuri N.; Tsetlin, Victor I.

    2012-01-01

    In Naja kaouthia cobra venom, we have earlier discovered a covalent dimeric form of α-cobratoxin (αCT-αCT) with two intermolecular disulfides, but we could not determine their positions. Here, we report the αCT-αCT crystal structure at 1.94 Å where intermolecular disulfides are identified between Cys3 in one protomer and Cys20 of the second, and vice versa. All remaining intramolecular disulfides, including the additional bridge between Cys26 and Cys30 in the central loops II, have the same positions as in monomeric α-cobratoxin. The three-finger fold is essentially preserved in each protomer, but the arrangement of the αCT-αCT dimer differs from those of noncovalent crystallographic dimers of three-finger toxins (TFT) or from the κ-bungarotoxin solution structure. Selective reduction of Cys26-Cys30 in one protomer does not affect the activity against the α7 nicotinic acetylcholine receptor (nAChR), whereas its reduction in both protomers almost prevents α7 nAChR recognition. On the contrary, reduction of one or both Cys26-Cys30 disulfides in αCT-αCT considerably potentiates inhibition of the α3β2 nAChR by the toxin. The heteromeric dimer of α-cobratoxin and cytotoxin has an activity similar to that of αCT-αCT against the α7 nAChR and is more active against α3β2 nAChRs. Our results demonstrate that at least one Cys26-Cys30 disulfide in covalent TFT dimers, similar to the monomeric TFTs, is essential for their recognition by α7 nAChR, although it is less important for interaction of covalent TFT dimers with the α3β2 nAChR. PMID:22223648

  13. Dimeric RNA recognition regulates HIV-1 genome packaging.

    PubMed

    Nikolaitchik, Olga A; Dilley, Kari A; Fu, William; Gorelick, Robert J; Tai, S-H Sheldon; Soheilian, Ferri; Ptak, Roger G; Nagashima, Kunio; Pathak, Vinay K; Hu, Wei-Shau

    2013-03-01

    How retroviruses regulate the amount of RNA genome packaged into each virion has remained a long-standing question. Our previous study showed that most HIV-1 particles contain two copies of viral RNA, indicating that the number of genomes packaged is tightly regulated. In this report, we examine the mechanism that controls the number of RNA genomes encapsidated into HIV-1 particles. We hypothesize that HIV-1 regulates genome packaging by either the mass or copy number of the viral RNA. These two distinct mechanisms predict different outcomes when the genome size deviates significantly from that of wild type. Regulation by RNA mass would result in multiple copies of a small genome or one copy of a large genome being packaged, whereas regulation by copy number would result in two copies of a genome being packaged independent of size. To distinguish between these two hypotheses, we examined the packaging of viral RNA that was larger (≈17 kb) or smaller (≈3 kb) than that of wild-type HIV-1 (≈9 kb) and found that most particles packaged two copies of the viral genome regardless of whether they were 17 kb or 3 kb. Therefore, HIV-1 regulates RNA genome encapsidation not by the mass of RNA but by packaging two copies of RNA. To further explore the mechanism that governs this regulation, we examined the packaging of viral RNAs containing two packaging signals that can form intermolecular dimers or intramolecular dimers (self-dimers) and found that one self-dimer is packaged. Therefore, HIV-1 recognizes one dimeric RNA instead of two copies of RNA. Our findings reveal that dimeric RNA recognition is the key mechanism that regulates HIV-1 genome encapsidation and provide insights into a critical step in the generation of infectious viruses.

  14. Dimerization of argon and the properties of its small clusters

    NASA Astrophysics Data System (ADS)

    Titov, S. V.; Serov, S. A.; Ostrovskii, G. M.

    2016-12-01

    Statistical thermodynamic means are used to study the bound state of a small cluster AN (2 ≤ N ≤ 5) of Lennard-Jones particles in a spherical cavity. The statistical sum is calculated by the Monte Carlo method. For the dimer, integration is reduced to quadratures. The integration region contains only phase space points corresponding to the bound cluster state. Dimerization constant 2A = A2 is calculated via the probability of finding a molecule in the bound state using the example of argon.

  15. Antagonizing STAT5B dimerization with an osmium complex

    PubMed Central

    Liu, Li-Juan; Wang, Wanhe; Kang, Tian-Shu; Liang, Jia-Xin; Liu, Chenfu; Kwong, Daniel W. J.; Wong, Vincent Kam Wai; Ma, Dik-Lung; Leung, Chung-Hang

    2016-01-01

    Targeting STAT5 is an appealing therapeutic strategy for the treatment of hematologic malignancies and inflammation. Here, we present the novel osmium(II) complex 1 as the first metal-based inhibitor of STAT5B dimerization. Complex 1 exhibited superior inhibitory activity against STAT5B DNA binding compared to STAT5A DNA binding. Moreover, 1 repressed STAT5B transcription and blocked STAT5B dimerization via binding to the STAT5B protein, thereby inhibiting STAT5B translocation to the nucleus. Furthermore, 1 was able to selectively inhibit STAT5B phosphorylation without affecting the expression level of STAT5B. PMID:27853239

  16. Facile dimer synthesis for DNA-binding polyamide ligands.

    PubMed

    Wetzler, Modi; Wemmer, David E

    2010-08-06

    Pyrrole-imidazole polyamide ligands are highly sequence specific synthetic DNA-binding ligands that bind with high affinity. To counter the synthetic difficulties associated with coupling the electron-rich heterocyclic acids to the electron-deficient nucleophilic imidazole amine, a novel approach is described for synthesis of Fmoc-protected dimers for solid-phase peptide synthesis (SPPS). This method produces the dimers in high yields, is broadly applicable to other heterocyclic-containing polyamides, and results in improved ligand yields and synthesis times.

  17. A Pfaffian Formula for Monomer-Dimer Partition Functions

    NASA Astrophysics Data System (ADS)

    Giuliani, Alessandro; Jauslin, Ian; Lieb, Elliott H.

    2016-04-01

    We consider the monomer-dimer partition function on arbitrary finite planar graphs and arbitrary monomer and dimer weights, with the restriction that the only non-zero monomer weights are those on the boundary. We prove a Pfaffian formula for the corresponding partition function. As a consequence of this result, multipoint boundary monomer correlation functions at close packing are shown to satisfy fermionic statistics. Our proof is based on the celebrated Kasteleyn theorem, combined with a theorem on Pfaffians proved by one of the authors, and a careful labeling and directing procedure of the vertices and edges of the graph.

  18. Styrene dimers and trimers affect reproduction of daphnid (Ceriodaphnia dubia).

    PubMed

    Tatarazako, Norihisa; Takao, Yuji; Kishi, Katsuyuki; Onikura, Norio a; Arizono, Koji; Iguchi, Taisen

    2002-08-01

    The endocrine disruptor activity of styrene in humans and other vertebrates appears to be negligible. However, offspring numbers were reduced in Ceriodaphnia dubia bred in polystyrene cups. Styrene dimers and trimers were found to be eluted from the polystyrene cups by hexane and methanol with gas chromatography-mass spectrometry. Styrene dimers and trimers at concentrations of 0.04-1.7 microg/l affected C. dubia fertility (25% reduction after seven days), suggesting that styrenes have the potential to impair crustacean populations in the aquatic environment.

  19. Dimerization of polycyclic aromatic hydrocarbons in soot nucleation.

    PubMed

    Zhang, Hong-Bo; You, Xiaoqing; Wang, Hongmiao; Law, Chung K

    2014-02-27

    A possible pathway of soot nucleation, in which localized π electrons play an important role in binding the polycyclic aromatic hydrocarbon (PAH) molecules having multiradical characteristics to form stable polymer molecules through covalent bonds, is studied using density functional and semiempirical methods. Results show that the number of covalent bonds formed in the dimerization of two identical PAHs is determined by the radical character, and the sites to form bonds are related to the aromaticity of individual six-membered ring structure. It is further shown that the binding energy of dimerization increases linearly with the diradical character in the range relevant to soot nucleation.

  20. Dimeric acylphloroglucinols from Hypericum austrobrasiliense exhibiting antinociceptive activity in mice.

    PubMed

    Bridi, Henrique; Ccana-Ccapatinta, Gari V; Stolz, Eveline D; Meirelles, Gabriela C; Bordignon, Sérgio A L; Rates, Stela M K; von Poser, Gilsane L

    2016-02-01

    Three dimeric acylphloroglucinols, austrobrasilol A, austrobrasilol B and isoaustrobrasilol B were isolated from the flowers of Hypericum austrobrasiliense (Hypericaceae, section Trigynobrathys). Their structures were elucidated using mass spectrometry and NMR experiments (1D and 2D), and by comparison with previously reported data for other dimeric acylphloroglucinols isolated from Hypericum and Elaphoglossum genera. The three compounds were orally administered in mice at equimolar doses to uliginosin B (15mg/kg, p.o.) displaying antinociceptive activity in the hot-plate test. The compounds did not induce motor impairment in the rotarod apparatus.

  1. C-Glucoside xanthone from the stem bark extract of Bersama engleriana

    PubMed Central

    Djemgou, Pierre C.; Hussien, Taha A.; Hegazy, Mohamed-Elamir F.; Ngandeu, François; Neguim, Gilles; Tane, Pierre; Mohamed, Abou-El-Hamd H.

    2010-01-01

    . Fractionation of the CH2Cl2-MeOH (1:1) extract of the stem bark of B. engleriana Guike gave mangiferin (1), in addition to three previously reported triterpenes, swinniol (2), Δ4-stigmaster-3β-ol (3), and 4-methylstigmaster-5,23-dien-3-β-ol (4). Conclusions: A chemical investigation of the CH2Cl2-MeOH extract of the stem bark of Bersama engleriana afforded a xanthone C-glucoside (mangiferin) and fi rst isolation of three terpenoids from this species: swinniol (2), Δ4-stigmaster-3β-ol (3), and 4-methylstigmaster-5,23-dien-3-β-ol (4). The complete 1H and 13C chemical shift assignments of mangiferin were determined using 1D and 2D NMR spectroscopic data (COSY, HMQC, HMBC, DEPT). The structures of the terpenoids were determined from their 1H and 13C NMR data and compared with the literature data. PMID:21808572

  2. Development and Validation of a Decigram-Scale Method for the Separation of Limonin from Limonin Glucoside by C-18 Flash Chromatography

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A preparative method for decigram-scale polishing of limonin glucoside with regard to removing traces of limonin, the main bitter principle in Citrus, is reported. During the method development and up-scaling stages, in which sample purity, sample size, solvent amounts, and drying conditions were v...

  3. Enhanced HPLC-DAD Method for Fast Determination of Quercetin-3-O-β-d-Glucoside in Extracts and Polyherbal Formulations Containing Azadirachta indica-Optimization and Validation.

    PubMed

    Desai, Sonal; Tatke, Pratima; Gabhe, Satish

    2017-03-18

    Azadirachta indica has been used for its medicinal properties since time immemorial. Herbal medicines which are prepared using this medicinal tree are utilized to treat various diseases and disorders. No reports are available for marker-based standardization of these herbal medicines prepared from leaves of A. indica. Also existing HPLC methods for determination quercetin-3-O-β-d-glucoside are time consuming. There is an obvious need for development of new HPLC method for quantification of quercetin-3-O-β-d-glucoside which is fast enough to carry out analysis in stipulated time period. This article deals with the development, optimization and validation of fast HPLC-DAD method for the determination of quercetin-3-O-β-d-glucoside in extracts containing A. indica for its successive application for marker-based standardization of herbal formulations containing A. indica. The retention time of quercetin-3-O-β-d-glucoside was 11.213 min. The method was found to be linear in the range of 4.0-60 µg mL-1. Limit of detection and limit of quantitation of the proposed method were found to be 1.33 and 4.0 µg mL-1, respectively. The mean recoveries were found to be within 93.53-103.75%. The method can be used as quality control tool for routine analysis of herbal extracts and formulations containing A. indicia.

  4. SGLT-1 Transport and Deglycosylation inside Intestinal Cells Are Key Steps in the Absorption and Disposition of Calycosin-7-O-β-d-Glucoside in Rats.

    PubMed

    Shi, Jian; Zheng, Haihui; Yu, Jia; Zhu, Lijun; Yan, Tongmeng; Wu, Peng; Lu, Linlin; Wang, Ying; Hu, Ming; Liu, Zhongqiu

    2016-03-01

    Hydrolysis by lactase-phloridzin hydrolase (LPH) is the first and critical step in the absorption of isoflavonoid glucosides. However, the absorption characteristics of calycosin-7-O-β-d-glucoside (CG) slightly differ from other isoflavonoid glucosides. In this study, we used the rat intestinal perfusion model and performed pharmacokinetic studies and in vitro experiments to determine the factors influencing CG absorption and disposition. After oral administration of isoflavonoid glucosides, LPH was found to play minimal or no role on the hydrolysis of CG, in contrast to that of daidzin. CG was mainly transported into the small intestinal cells by sodium-dependent glucose transporter 1 (SGLT-1) as intact. This pathway could be the main mechanism underlying the high permeability of CG in the small intestine. CG was likely to be hydrolyzed in enterocytes to its aglycone calycosin by broad-specific β-glucuronides (BSβG) and glucocerebrosidase or rapidly metabolized. Calycosin was also rapidly and extensively metabolized to 3'-glucuronide in the enterocytes and liver, and the glucuronidation rates of calycosin and CG were much higher in the former. The metabolites were also transported into lumen by breast cancer resistance protein and multidrug resistance-associated protein 2. In conclusion, the enterocytes could be an important site for CG absorption, deglycosylation, and metabolism in rats. This study could contribute to the theoretical foundation and mechanism of absorption and disposition of flavonoid compounds.

  5. A Versatile Family 3 Glycoside Hydrolase from Bifidobacterium adolescentis Hydrolyzes β-Glucosides of the Fusarium Mycotoxins Deoxynivalenol, Nivalenol, and HT-2 Toxin in Cereal Matrices

    PubMed Central

    Varga, Elisabeth; Malachova, Alexandra; Nguyen, Nhung Thi; Lorenz, Cindy; Haltrich, Dietmar; Berthiller, Franz; Adam, Gerhard

    2015-01-01

    Glycosylation plays a central role in plant defense against xenobiotics, including mycotoxins. Glucoconjugates of Fusarium toxins, such as deoxynivalenol-3-O-β-d-glucoside (DON-3G), often cooccur with their parental toxins in cereal-based food and feed. To date, only limited information exists on the occurrence of glucosylated mycotoxins and their toxicological relevance. Due to a lack of analytical standards and the requirement of high-end analytical instrumentation for their direct determination, hydrolytic cleavage of β-glucosides followed by analysis of the released parental toxins has been proposed as an indirect determination approach. This study compares the abilities of several fungal and recombinant bacterial β-glucosidases to hydrolyze the model analyte DON-3G. Furthermore, substrate specificities of two fungal and two bacterial (Lactobacillus brevis and Bifidobacterium adolescentis) glycoside hydrolase family 3 β-glucosidases were evaluated on a broader range of substrates. The purified recombinant enzyme from B. adolescentis (BaBgl) displayed high flexibility in substrate specificity and exerted the highest hydrolytic activity toward 3-O-β-d-glucosides of the trichothecenes deoxynivalenol (DON), nivalenol, and HT-2 toxin. A Km of 5.4 mM and a Vmax of 16 μmol min−1 mg−1 were determined with DON-3G. Due to low product inhibition (DON and glucose) and sufficient activity in several extracts of cereal matrices, this enzyme has the potential to be used for indirect analyses of trichothecene-β-glucosides in cereal samples. PMID:25979885

  6. Separation of vitexin-4″-O-glucoside and vitexin-2″-O-rhamnoside from hawthorn leaves extracts using macroporous resins.

    PubMed

    Li, Hongjuan; Liu, Ying; Jin, Haizhu; Liu, Sujing; Fang, Shengtao; Wang, Chunhua; Xia, Chuanhai

    2015-12-15

    Vitexin-4″-O-glucoside and vitexin-2″-O-rhamnoside are the major flavonoids of hawthorn leaves. In this work, the adsorption and desorption characteristics of vitexin-4″-O-glucoside and vitexin-2″-O-rhamnoside on seven macroporous resins were evaluated. Among the tested resins, the HPD-400 resin showed the best adsorption and desorption capacities. Adsorption isotherms were constructed for the HPD-400 resin and well fitted to Langmuir and Freundlich models. Dynamic adsorption and desorption tests were performed on column packed with the HPD-400 resin to optimize the chromatographic parameters. After one run treatment with the HPD-400 resin, the contents of vitexin-4″-O-glucoside and vitexin-2″-O-rhamnoside in the product were increased 8.44-fold and 8.43-fold from 0.720% and 2.63% to 6.08% and 22.2% with recovery yields of 79.1% and 81.2%, respectively. These results show that the developed method is a promising basis for the large-scale purification of vitexin-4″-O-glucoside and vitexin-2″-O-rhamnoside from hawthorn leaves and other plant materials.

  7. Determination of citrus limonoid glucosides by high performance liquid chromatography coupled to post-column reaction with Ehrlich’s Reagent

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A method for the identification and quantification of citrus limonoid glucosides in juices based upon high performance liquid chromatography (HPLC) separation coupled to post-column reaction with Ehrlichs’s reagent has been developed. This method utilizes a phenyl stationary phase and an isocratic ...

  8. Adaption of Ehrlich’s Reagent to a HPLC post-column reaction system for the quantification of limonoid glucosides (abstract)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrus limonoid glucosides are found in large quantities in citrus fruits and seeds. Characterization and quantification of these compounds is important because they contribute to citrus quality and are reported to be biologically active. Unlike other bioactive compounds (e.g., flavonoids) present...

  9. Effect of pH on the complexation of kaempferol-4'-glucoside with three β-cyclodextrin derivatives: isothermal titration calorimetry and spectroscopy study.

    PubMed

    Zheng, Yan; Dong, Li-Na; Liu, Min; Chen, Aiju; Feng, Shangcai; Wang, Bingquan; Sun, Dezhi

    2014-01-08

    The utilization of kaempferol and its glycosides in food and pharmaceutical industries could be improved by the formation of inclusion complexes with cyclodextrins at different pH. This study explores the complexation of kaempferol-4'-glucoside with sulfobutyl ether-β-cyclodextrin (SBE-β-CD), hydroxypropyl-β-cyclodextrin (HP-β-CD), and methylated-β-cyclodextrin (M-β-CD) in phosphate buffer solutions of different pH using isothermal titration calorimetry, UV-vis absorption and proton nuclear magnetic resonance spectroscopy at 298.2 K. Experimental results showed that kaempferol-4'-glucoside binds with the three β- cyclodextrins in the same 1:1 stoichiometry. The rank order of stability constants is SBE-β-CD > HP-β-CD > M-β-CD at the same pH level and pH 6.0 > pH 7.4 > pH 9.0 for the same cyclodextrin. The binding of kaempferol-4'-glucoside with the three β-cyclodextrin derivatives is synergistically driven by enthalpy and entropy at pH 6.0 and enthalpy-driven at pH 7.4 and 9.0. The possible inclusion mode was that in the cavity of β-CD is included the planar benzopyranic-4-one part of the kaempferol-4'-glucoside.

  10. Structure and Mechanism of the Influenza A M218-60 Dimer of Dimers.

    PubMed

    Andreas, Loren B; Reese, Marcel; Eddy, Matthew T; Gelev, Vladimir; Ni, Qing Zhe; Miller, Eric A; Emsley, Lyndon; Pintacuda, Guido; Chou, James J; Griffin, Robert G

    2015-12-02

    We report a magic angle spinning (MAS) NMR structure of the drug-resistant S31N mutation of M218-60 from Influenza A. The protein was dispersed in diphytanoyl-sn-glycero-3-phosphocholine lipid bilayers, and the spectra and an extensive set of constraints indicate that M218-60 consists of a dimer of dimers. In particular, ∼280 structural constraints were obtained using dipole recoupling experiments that yielded well-resolved (13)C-(15)N, (13)C-(13)C, and (1)H-(15)N 2D, 3D, and 4D MAS spectra, all of which show cross-peak doubling. Interhelical distances were measured using mixed (15)N/(13)C labeling and with deuterated protein, MAS at ωr/2π = 60 kHz, ω0H/2π = 1000 MHz, and (1)H detection of methyl-methyl contacts. The experiments reveal a compact structure consisting of a tetramer composed of four transmembrane helices, in which two opposing helices are displaced and rotated in the direction of the membrane normal relative to a four-fold symmetric arrangement, yielding a two-fold symmetric structure. Side chain conformations of the important gating and pH-sensing residues W41 and H37 are found to differ markedly from four-fold symmetry. The rmsd of the structure is 0.7 Å for backbone heavy atoms and 1.1 Å for all heavy atoms. This two-fold symmetric structure is different from all of the previous structures of M2, many of which were determined in detergent and/or with shorter constructs that are not fully active. The structure has implications for the mechanism of H(+) transport since the distance between His and Trp residues on different helices is found to be short. The structure also exhibits two-fold symmetry in the vicinity of the binding site of adamantyl inhibitors, and steric constraints may explain the mechanism of the drug-resistant S31N mutation.

  11. Application of ESI/MS, CID/MS and tandem MS/MS to the fragmentation study of eriodictyol 7-O-glucosyl-(1-->2)-glucoside and luteolin 7-O-glucosyl-(1-->2)-glucoside

    NASA Astrophysics Data System (ADS)

    Es-Safi, Nour-Eddine; Kerhoas, Lucien; Einhorn, Jacques; Ducrot, Paul-Henri

    2005-12-01

    A mass spectrometric method based on the combined use of positive and negative electrospray ionization, collision-induced dissociation and tandem mass spectrometry has been applied to the structural characterization of the eriodictyol 7-O-glucosyl-(1-->2)-glucoside and luteolin 7-O-glucosyl-(1-->2)-glucoside. The low-energy product ion mass spectrum of [M + H]+ and [M - H]- ions showed extensive fragmentation of the diglucose moiety, loss of the glycan residue, and fragmentation of the aglycon units that permit characterization of the interglycosidic linkage and the substituents in the A- and B-rings. Both glycosides were shown to yield the 0,2X00,2X1 ion which can be considered as characteristic of the 1-->2 interglycosidic linkage in the glucoglucoside adducts, since it can not be formed in the case of other interglycosidic types. In the case of the eriodictyol diglucoside the 1, 3 fragmentation of the C-ring was observed before those involving the carbohydrates thus allowing the position determination of the diglucoside moiety on the A-ring. In the negative ion mode only the luteolin diglucoside was shown to undergo collision-induced homolytic and heterolytic cleavages of the O-glycosidic bond producing the aglycone radical-anion [Y0-H]-- and Y0- product ions, while this was not observed in the case of eriodictyol glycoside. CID MS/MS analysis of the sodiated molecules gave complementary informations for the structural characterization of the studied compounds. The B2+ fragment which is useful for establishing that the terminal carbohydrate unit is linked to another carbohydrate and not directly to the aglycone was obtained as base peak. This result is of analytical value for the differentiation of O-diglycosyl and di-O-glycosyl flavonoids.

  12. Biophysical Characterization of the Dimer and Tetramer Interface Interactions of the Human Cytosolic Malic Enzyme

    PubMed Central

    Murugan, Sujithkumar; Hung, Hui-Chih

    2012-01-01

    The cytosolic NADP+-dependent malic enzyme (c-NADP-ME) has a dimer-dimer quaternary structure in which the dimer interface associates more tightly than the tetramer interface. In this study, the urea-induced unfolding process of the c-NADP-ME interface mutants was monitored using fluorescence and circular dichroism spectroscopy, analytical ultracentrifugation and enzyme activities. Here, we demonstrate the differential protein stability between dimer and tetramer interface interactions of human c-NADP-ME. Our data clearly demonstrate that the protein stability of c-NADP-ME is affected predominantly by disruptions at the dimer interface rather than at the tetramer interface. First, during thermal stability experiments, the melting temperatures of the wild-type and tetramer interface mutants are 8–10°C higher than those of the dimer interface mutants. Second, during urea denaturation experiments, the thermodynamic parameters of the wild-type and tetramer interface mutants are almost identical. However, for the dimer interface mutants, the first transition of the urea unfolding curves shift towards a lower urea concentration, and the unfolding intermediate exist at a lower urea concentration. Third, for tetrameric WT c-NADP-ME, the enzyme is first dissociated from a tetramer to dimers before the 2 M urea treatment, and the dimers then dissociated into monomers before the 2.5 M urea treatment. With a dimeric tetramer interface mutant (H142A/D568A), the dimer completely dissociated into monomers after a 2.5 M urea treatment, while for a dimeric dimer interface mutant (H51A/D90A), the dimer completely dissociated into monomers after a 1.5 M urea treatment, indicating that the interactions of c-NADP-ME at the dimer interface are truly stronger than at the tetramer interface. Thus, this study provides a reasonable explanation for why malic enzymes need to assemble as a dimer of dimers. PMID:23284632

  13. Identification, amounts, and kinetics of extraction of C-glucosidic ellagitannins during wine aging in oak barrels or in stainless steel tanks with oak chips.

    PubMed

    Jourdes, Michaël; Michel, Julien; Saucier, Cédric; Quideau, Stéphane; Teissedre, Pierre-Louis

    2011-09-01

    The C-glucosidic ellagitannins are found in wine as a result of its aging in oak barrels or in stainless steel tanks with oak chips. Once dissolved in this slightly acidic solution, the C-glucosidic ellagitannins vescalagin can react with nucleophilic entities present in red wine, such as ethanol, catechin, and epicatechin, to generate condensed hybrid products such as the β-1-O-ethylvescalagin and the flavano-ellagitannins (acutissimin A/B and epiacutissimin A/B), respectively. During this study, we first monitored the extraction kinetic and the evolution of the eight major oak-derived C-glucosidic ellagitannins in red wines aged in oak barrels or in stainless steel tank with oak chips. Their extraction rates appeared to be faster during red wine aging in stainless steel tanks with oak chips. However, their overall concentrations in wines were found higher in the wine aged in barrels. The formation rates of the vescalagin-coupled derivatives were also estimated for the first time under both red wine aging conditions (i.e., oak barrels or stainless steel tanks with oak chips). As observed for the oak-native C-glucosidic ellagitannins, the concentrations of these vescalagin derivatives were higher in the red wine aged in oak barrels than in stainless steel tanks with oak chips. Despite these differences, their relative composition was similar under both red wine aging conditions. Finally, the impact of the oak chips size and toasting level on the C-glucosidic ellagitannins concentration in wine was also investigated.

  14. Effect of the solvatation shell exchange on the formation of malvidin-3-O-glucoside-ellagic acid complexes.

    PubMed

    Kunsagi-Maté, Sandor; Ortmann, Erika; Kollar, Laszló; Nikfardjam, Martin Pour

    2007-10-11

    The interaction of malvidin-3-O-glucoside with ellagic acid was studied in aqueous solutions in dependence of the ethanol content of the samples. The results show significant changes of the thermodynamic parameters when the ethanol content exceeds 8%vol. The quantum chemical calculations and the solvent relaxation measurements validate that the solvatation shell of the malvidin-ellagic acid complexes changes from water to ethanol around this critical alcoholic concentration. The change of the solvate shell is accompanied by increasing copigmentation; i.e., higher "multi-sandwich" complexes are formed. According to the considerable role of this interaction (namely copigmentation) in the formation of color in red wines, our results have several consequences for the winemaking process with regard to the stabilization of wine color.

  15. Cyanidin-3-o-glucoside directly binds to ERα36 and inhibits EGFR-positive triple-negative breast cancer

    PubMed Central

    Yang, Shiping; Ma, Wenqiang; Liu, Mei; Guo, Shichao; Zhan, Jun; Zhang, Hongquan; Tsang, Suk Ying; Zhang, Ziding; Wang, Zhaoyi; Li, Xiru; Guo, Yang-Dong; Li, Xiangdong

    2016-01-01

    Anthocyanins have been shown to inhibit the growth and metastatic potential of breast cancer (BC) cells. However, the effects of individual anthocyanins on triple-negative breast cancer (TNBC) have not yet been studied. In this study, we found that cyanidin-3-o-glucoside (Cy-3-glu) preferentially promotes the apoptosis of TNBC cells, which co-express the estrogen receptor alpha 36 (ERα36) and the epidermal growth factor receptor (EGFR). We demonstrated that Cy-3-glu directly binds to the ligand-binding domain (LBD) of ERα36, inhibits EGFR/AKT signaling, and promotes EGFR degradation. We also confirmed the therapeutic efficacy of Cy-3-glu on TNBC in the xenograft mouse model. Our data indicates that Cy-3-glu could be a novel preventive/therapeutic agent against the TNBC co-expressed ERα36/EGFR. PMID:27655695

  16. Purification of an isoflavonoid 7-O-beta-apiosyl-glucoside beta-glycosidase and its substrates from Dalbergia nigrescens Kurz.

    PubMed

    Chuankhayan, Phimonphan; Hua, Yanling; Svasti, Jisnuson; Sakdarat, Santi; Sullivan, Patrick A; Ketudat Cairns, James R

    2005-08-01

    A beta-glycosidase was purified from the seeds of Dalbergia nigescens Kurz based on its ability to hydrolyse p-nitrophenyl beta-glucoside and beta-fucoside. This enzyme did not hydrolyze various glycosidic substrates efficiently, so it was used to identify its own natural substrates. Two substrates were identified, isolated and their structures determined as: compound 1, dalpatein 7-O-beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyranoside and compound 2, 6,2',4',5'-tetramethoxy-7-hydroxy-7-O-beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyranoside (dalnigrein7-O-beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyranoside). The beta-glycosidase removes the sugar from these glycosides as a disaccharide, despite its initial identification as a beta-glucosidase and beta-fucosidase.

  17. Melanin biosynthesis inhibitory and antioxidant activities of quercetin-3'-O-beta-D-glucoside isolated from Allium cepa.

    PubMed

    Arung, Enos Tangke; Furuta, Shoko; Ishikawa, Hiroya; Tanaka, Hiroyuki; Shimizu, Kuniyoshi; Kondo, Ryuichiro

    2011-01-01

    In the course of searching for new whitening agents, we have found that the methanol extract of dried skin of Allium cepa shows potent melanin biosynthesis inhibitory activity in B16 melanoma cells. Bioassay-guided fractionation led to the isolation of quercetin-3'-O-beta-D-glucoside (1) from the methanol extract of dried skin of A. cepa, which inhibited melanin formation in B16 melanoma cells with an IC50 value of 38.8 microM and mushroom tyrosinase with an IC50 value of 6.5 microM using L-tyrosine and 48.5 microM using L-dihydroxyphenylalanine as substrates, respectively. In addition, the antioxidant activity of 1 was evaluated in the oxygen radical absorbance capacity assay; it showed 3.04 micromol Trolox equivalents/mmol. 1 was shown to be a promising ingredient that could be useful for treating hyperpigmentation and for protecting against oxidative stress.

  18. Validated HPLC method for simultaneous estimation of khellol glucoside, khellin and visnagin in Ammi visnaga L. fruits and pharmaceutical preparations.

    PubMed

    Badr, Jihan M; Hadad, Ghada M; Nahriry, Khaled; Hassanean, Hashem A

    2015-01-01

    Tea bags including fruits of Ammi visnaga L. are used in Egypt as remedy for the treatment of kidney stones. Our study focuses on developing simple and rapid method utilising HPLC for quantitative estimation of khellol glucoside (KG), khellin (KH) and visnagin (VS) simultaneously. Their concentrations were determined in A. visnaga L. fruits at different developmental stages and in pharmaceutical formulations together with following up them during shelf life. Separation was accomplished using HPLC. Perfect resolution between KG, KH and VS was possible through using a mobile phase consisting of water:methanol:tetrahydrofuran (50:45:5, v/v/v). Peaks were detected at 245 nm. The suggested method for the determination of KG, KH and VS was successful in determining the analytes of interest without any interference of other compounds and matrix. All validation parameters were satisfactory and the procedure was relatively easy and fast as extracts are evaluated without previous steps of purification.

  19. G domain dimerization controls dynamin's assembly-stimulated GTPase activity

    SciTech Connect

    Chappie, Joshua S.; Acharya, Sharmistha; Leonard, Marilyn; Schmid, Sandra L.; Dyda, Fred

    2010-06-14

    Dynamin is an atypical GTPase that catalyses membrane fission during clathrin-mediated endocytosis. The mechanisms of dynamin's basal and assembly-stimulated GTP hydrolysis are unknown, though both are indirectly influenced by the GTPase effector domain (GED). Here we present the 2.0 {angstrom} resolution crystal structure of a human dynamin 1-derived minimal GTPase-GED fusion protein, which was dimeric in the presence of the transition state mimic GDP.AlF{sub 4}{sup -}. The structure reveals dynamin's catalytic machinery and explains how assembly-stimulated GTP hydrolysis is achieved through G domain dimerization. A sodium ion present in the active site suggests that dynamin uses a cation to compensate for the developing negative charge in the transition state in the absence of an arginine finger. Structural comparison to the rat dynamin G domain reveals key conformational changes that promote G domain dimerization and stimulated hydrolysis. The structure of the GTPase-GED fusion protein dimer provides insight into the mechanisms underlying dynamin-catalysed membrane fission.

  20. Comparative assay of antioxidant packages for dimer of estolide esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A series of 26 different antioxidants and commercial antioxidant packages, containing both natural and synthetic-based materials, were evaluated with dimeric coconut-oleic estolide 2-ethylhexyl ester. The different antioxidants were broken down into different classes of materials: phenolic, aminic, ...

  1. The Internal Structure of Nanoparticle Dimers Linked by DNA

    NASA Astrophysics Data System (ADS)

    Vargas Lara, Fernando; Cheng, Ching-Jung; Gang, Oleg; Starr, Francis W.

    2012-02-01

    The self-assembly of inorganic units controlled by the interactions of biological molecules, like DNA, has received attention for the possibility to specify higher-order structure, with potential biological, optical and electronic applications. In biology, self-assembly of complex materials (eg. bone, spider silk) frequently occurs in a stepwise, hierarchical fashion. Here, we consider a first step towards a hierarchical approach for synthetic nanostructures of nanoparticles (NPs) linked by DNA. The most basic unit in this multiscale approach is a dimer of NPs linked by DNA. We use a coarse-grained molecular model to explain experimental measurements of the separation of two DNA-coated NPs connected by linking single-stranded DNA (ssDNA). We show that the dimer separation is primarily controlled by the number of DNA links between NPs. If these links are not constrained to lie along the axis between NPs, the separation is limited by off-axis connections that force the NPs to be closer. We also determine how the number of connections alters the effective persistence length of the ssDNA that connects the dimer. We discuss how these dimers might be used for subsequent assembly at larger scales.

  2. Cantharimide dimers from the Chinese blister beetle, Mylabris phalerate PALLAS.

    PubMed

    Nakatani, Takafumi; Jinpo, Katsuaki; Noda, Naoki

    2007-01-01

    Five cantharidin-related compounds were isolated from the Chinese blister beetle, Mylabris phalerate PALLAS (Meloidae). Their structures were determined based on spectroscopic and chemical evidence. Three of them were identified as cantharimide dimers, which consist of two units of cantharimide combined with a tri-, tetra-, or penta-methylene group.

  3. Dimeric pyrrole-imidazole alkaloids: synthetic approaches and biosynthetic hypotheses.

    PubMed

    Wang, Xiao; Ma, Zhiqiang; Wang, Xiaolei; De, Saptarshi; Ma, Yuyong; Chen, Chuo

    2014-08-14

    The pyrrole-imidazole alkaloids are a group of structurally unique and biologically interesting marine sponge metabolites. Among them, the cyclic dimers have caught synthetic chemists' attention particularly. Numerous synthetic strategies have been developed and various biosynthetic hypotheses have been proposed for these fascinating natural products. We discuss herein the synthetic approaches and the biosynthetic insights obtained from these studies.

  4. DNAzyme-Controlled Cleavage of Dimer and Trimer Origami Tiles.

    PubMed

    Wu, Na; Willner, Itamar

    2016-04-13

    Dimers of origami tiles are bridged by the Pb(2+)-dependent DNAzyme sequence and its substrate or by the histidine-dependent DNAzyme sequence and its substrate to yield the dimers T1-T2 and T3-T4, respectively. The dimers are cleaved to monomer tiles in the presence of Pb(2+)-ions or histidine as triggers. Similarly, trimers of origami tiles are constructed by bridging the tiles with the Pb(2+)-ion-dependent DNAzyme sequence and the histidine-dependent DNAzyme sequence and their substrates yielding the trimer T1-T5-T4. In the presence of Pb(2+)-ions and/or histidine as triggers, the programmed cleavage of trimer proceeds. Using Pb(2+) or histidine as trigger cleaves the trimer to yield T5-T4 and T1 or the dimer T1-T5 and T4, respectively. In the presence of Pb(2+)-ions and histidine as triggers, the cleavage products are the monomer tiles T1, T5, and T4. The different cleavage products are identified by labeling the tiles with 0, 1, or 2 streptavidin labels and AFM imaging.

  5. Asymptotics of Height Change on Toroidal Temperleyan Dimer Models

    NASA Astrophysics Data System (ADS)

    Dubédat, Julien; Gheissari, Reza

    2015-04-01

    The dimer model is an exactly solvable model of planar statistical mechanics. In its critical phase, various aspects of its scaling limit are known to be described by the Gaussian free field. For periodic graphs, criticality is an algebraic condition on the spectral curve of the model, determined by the edge weights (Kenyon et al. in Ann Math (2) 163(3):1019-1056, 2006); isoradial graphs provide another class of critical dimer models, in which the edge weights are determined by the local geometry. In the present article, we consider another class of graphs: general Temperleyan graphs, i.e. graphs arising in the (generalized) Temperley bijection between spanning trees and dimer models. Building in particular on Forman's formula and representations of Laplacian determinants in terms of Poisson operators, and under a minimal assumption—viz. that the underlying random walk converges to Brownian motion—we show that the natural topological observable on macroscopic tori converges in law to its universal limit, i.e. the law of the periods of the dimer height function converges to that of the periods of a compactified free field.

  6. Potential Energy Surface Database of Group II Dimer

    National Institute of Standards and Technology Data Gateway

    SRD 143 NIST Potential Energy Surface Database of Group II Dimer (Web, free access)   This database provides critical atomic and molecular data needed in order to evaluate the feasibility of using laser cooled and trapped Group II atomic species (Mg, Ca, Sr, and Ba) for ultra-precise optical clocks or quantum information processing devices.

  7. Hydrazine-mediated strongly coupled Re(CO)3 dimers.

    PubMed

    Hasheminasab, A; Rhoda, H M; Crandall, L A; Ayers, J T; Nemykin, V N; Herrick, R S; Ziegler, C J

    2015-10-21

    Dimeric metal complexes can often exhibit coupling interactions via bridging ligands. In this report, we present two Re(CO)3 dimers, where the metals are linked via a bis(pyca) hydrazine (pyca = pyridine-2-carbaldehyde imine) Schiff base ligand. For the dimeric compounds 4 and 5, we observe strong coupling across the dimer as measured by cyclic voltammetry: ∼480 mV separations between the first and the second reduction waves that correspond to comproportionation constants close to 1.5 × 10(8). Evidence for a mixed valence state upon one electron reduction was also observed by spectroelectrochemistry in which a clear inter-valence charge-transfer (IVCT) band was observed in [4]- and [5]-complexes. The electronic structures of all target compounds were probed by DFT and TDDFT computational methods. DFT calculations indicate that reduction takes place at the diimine units, and that the observed coupling is a ligand-based phenomenon, rather than one that involves metal-based orbitals.

  8. Ising anyons in frustration-free Majorana-dimer models

    NASA Astrophysics Data System (ADS)

    Ware, Brayden; Son, Jun Ho; Cheng, Meng; Mishmash, Ryan V.; Alicea, Jason; Bauer, Bela

    2016-09-01

    Dimer models have long been a fruitful playground for understanding topological physics. Here, we introduce a class, termed Majorana-dimer models, wherein bosonic dimers are decorated with pairs of Majorana modes. We find that the simplest examples of such systems realize an intriguing, intrinsically fermionic phase of matter that can be viewed as the product of a chiral Ising theory, which hosts deconfined non-Abelian quasiparticles, and a topological px-i py superconductor. While the bulk anyons are described by a single copy of the Ising theory, the edge remains fully gapped. Consequently, this phase can arise in exactly solvable, frustration-free models. We describe two parent Hamiltonians: one generalizes the well-known dimer model on the triangular lattice, while the other is most naturally understood as a model of decorated fluctuating loops on a honeycomb lattice. Using modular transformations, we show that the ground-state manifold of the latter model unambiguously exhibits all properties of the Ising×(px-i py) theory. We also discuss generalizations with more than one Majorana mode per site, which realize phases related to Kitaev's 16-fold way in a similar fashion.

  9. Transporting testosterone and its dimers by serum proteins.

    PubMed

    Chanphai, P; Vesper, A R; Bekale, L; Bérubé, G; Tajmir-Riahi, H A

    2015-12-01

    A substantial part of steroids is bound to serum proteins in vivo. We report the association of testosterone and it aliphatic dimer (alip) and aromatic dimer (arom) with human serum albumin (HSA) and bovine serum albumin (BSA) in aqueous solution at physiological pH. Multiple spectroscopic methods, transmission electron microscopy (TEM) and molecular modeling were used to characterize steroid-protein binding and protein aggregation process. Spectroscopic analysis showed that steroids bind protein via hydrophobic, hydrophilic and H-bonding interactions. HSA forms more stable complexes than BSA. The binding affinity of steroid-protein adducts is testosterone>dimer-aromatic>dimer-aliphatic. Transmission electron microscopy showed major changes in protein morphology as steroid-protein complexation occurred with increase in the diameter of the protein aggregate indicating encapsulation of steroids by serum proteins. Modeling showed the presence of H-bonding stabilized testosterone-protein complexes with the free binding energy of -12.95 for HSA and -11.55 kcal/mol for BSA, indicating that the interaction process is spontaneous at room temperature. Steroid complexation induced more perturbations of BSA conformation than HSA.

  10. Percolation of heteronuclear dimers irreversibly deposited on square lattices

    NASA Astrophysics Data System (ADS)

    Gimenez, M. C.; Ramirez-Pastor, A. J.

    2016-09-01

    The percolation problem of irreversibly deposited heteronuclear dimers on square lattices is studied. A dimer is composed of two segments, and it occupies two adjacent adsorption sites. Each segment can be either a conductive segment (segment type A ) or a nonconductive segment (segment type B ). Three types of dimers are considered: A A , B B , and A B . The connectivity analysis is carried out by accounting only for the conductive segments (segments type A ). The model offers a simplified representation of the problem of percolation of defective (nonideal) particles, where the presence of defects in the system is simulated by introducing a mixture of conductive and nonconductive segments. Different cases were investigated, according to the sequence of deposition of the particles, the types of dimers involved in the process, and the degree of alignment of the deposited objects. By means of numerical simulations and finite-size scaling analysis, the complete phase diagram separating a percolating from a nonpercolating region was determined for each case. Finally, the consistency of our results was examined by comparing with previous data in the literature for linear k -mers (particles occupying k adjacent sites) with defects.

  11. Centrosymmetric dimer of quinuclidine betaine and squaric acid complex

    NASA Astrophysics Data System (ADS)

    Dega-Szafran, Z.; Katrusiak, A.; Szafran, M.

    2012-12-01

    The complex of squaric acid (3,4-dihydroxy-3-cyclobuten-1,2-dion, H2SQ) with quinuclidine betaine (1-carboxymethyl-1-azabicyclo[2.2.2]octane inner salt, QNB), 1, has been characterized by single-crystal X-ray analysis, FTIR and NMR spectroscopies and by DFT calculations. In the crystal of 1, monoclinic space group P21/n, one proton from H2SQ is transferred to QNB. QNBH+ and HSQ- are linked together by a Osbnd H⋯O hydrogen bond of 2.553(2) Å. Two such QNBH+·HSQ- complexes form a centrosymmetric dimer bridged by two Osbnd H⋯O bonds of 2.536(2) Å. The FTIR spectrum is consistent with the X-ray results. The structures of monomer QNBH+·HSQ- (1a) and dimer [QNB·H2SQ]2 (2) have been optimized at the B3LYP/6-311++G(d,p) level of theory. Isolated dimer 2 optimized back to a molecular aggregate of H2SQ and QNB. The calculated frequencies for the optimized structure of dimer 2 have been used to explain the frequencies of the experimental FTIR spectrum. The interpretation of 1H and 13C NMR spectra has been based on the calculated GIAO/B3LYP/6-311++G(d,p) magnetic isotropic shielding constants for monomer 1a.

  12. Percolation of heteronuclear dimers irreversibly deposited on square lattices.

    PubMed

    Gimenez, M C; Ramirez-Pastor, A J

    2016-09-01

    The percolation problem of irreversibly deposited heteronuclear dimers on square lattices is studied. A dimer is composed of two segments, and it occupies two adjacent adsorption sites. Each segment can be either a conductive segment (segment type A) or a nonconductive segment (segment type B). Three types of dimers are considered: AA, BB, and AB. The connectivity analysis is carried out by accounting only for the conductive segments (segments type A). The model offers a simplified representation of the problem of percolation of defective (nonideal) particles, where the presence of defects in the system is simulated by introducing a mixture of conductive and nonconductive segments. Different cases were investigated, according to the sequence of deposition of the particles, the types of dimers involved in the process, and the degree of alignment of the deposited objects. By means of numerical simulations and finite-size scaling analysis, the complete phase diagram separating a percolating from a nonpercolating region was determined for each case. Finally, the consistency of our results was examined by comparing with previous data in the literature for linear k-mers (particles occupying k adjacent sites) with defects.

  13. CTG-loaded liposomes as an approach for improving the intestinal absorption of asiaticoside in Centella Total Glucosides.

    PubMed

    Wang, Jiayu; Ma, Changhua; Guo, Chengjie; Yuan, Ruijuan; Zhan, Xueyan

    2016-07-25

    Centella Total Glucosides (CTG),obtained from Centella asiatica (L.), have been shown to possess a multitude of pharmacological activities, however, oral administeration of CTG failed to fulfill their therapeutic potentials due to the low bioavailability. In this study, the author prepared the liposomes encapsulated CTG using the ethanol injection method in order to enhance their intestinal absorption. The average particle size and the polydispersityindex(PDI) of CTG-loaded liposome in a batch are 137.0nm and 0.283, and the CTG-loaded amounts in CTG-loaded liposomes were 0.177mgmL(-1) and the zeta potential of CTG-loaded lipsomes is -21.2mV. The TEM images of CTG-loaded lipsomes showed that CTG-loaded liposomes are round and maintain high structural integrity, and their DSC thermograms indicated that CTG might be incorporated into the aqueous phase of DPPC to become more stable. The everted rat gut sac model was used to study the absorption characteristic of CTG-loaded solution in rat intestines. The cumulative absorption amount (Q) and the cumulative absorption percentage (P%) of asiaticoside in the CTG-loaded liposome was significantly higher than that in CTG (P<0.05), both the steady-state infiltration rate (Jss, μgcm(-2)s(-1)) and the permeability coefficient (Papp, cms(-1)) of asiaticoside in CTG-loaded liposomes were significantly higher than those in CTG (P<0.05), which revealed that the liposomes encapsulated CTG can promote the absorption of asiaticoside in the ileum of the rats by enhancing its transmembrane permeability. The above study will provide the experimental evidence and a reference for the development of the oral dosage forms of Centella total glucosides.

  14. Biosynthesis of geraniol and nerol and their β-d-glucosides in Perlargonium graveolens and Rosa dilecta

    PubMed Central

    Banthorpe, Derek V.; Le Patourel, Geoffrey N. J.; Francis, Martin J. O.

    1972-01-01

    1. 3R-[2-14C]Mevalonate was incorporated into geranyl and neryl β-d-glucosides in petals of Rosa dilecta in up to 10.6% yield, and the terpenoid part was specifically and equivalently labelled in the moieties derived from isopentenyl pyrophosphate and 3,3-dimethylallyl pyrophosphate. A similar labelling pattern, with incorporations of 0.06–0.1% was found for geraniol or nerol formed in leaves of Pelargonium graveolens The former results provide the best available evidence for the mevalonoid route to regular monoterpenes in higher plants. 2. Incorporation studies with 3RS-[2-14C,(4R)-4-3H1]-mevalonate and its (4S)-isomer showed that the pro-4R hydrogen atom of the precursor was retained and the pro-4S hydrogen atom was eliminated in both alcohols and both glucosides. These results suggest that the correlation of retention of the pro-4S hydrogen atom of mevalonate with formation of a cis-substituted double bond, such as has been found in certain higher terpenoids, does not apply to the biosynthesis of monoterpenes. It is proposed that either nerol is derived from isomerization of geraniol or the two alcohols are directly formed by different prenyltransferases. Possible mechanisms for these processes are discussed. 3. The experiments with [14C,3H]mevalonate also show that in these higher plants, as has been previously found in animal tissue and yeast, the pro-4S hydrogen atom of mevalonate was lost in the conversion of isopentenyl pyrophosphate into 3,3-dimethylallyl pyrophosphate. PMID:4348258

  15. Synthesis, characterization, OFET and electrochemical properties of novel dimeric metallophthalocyanines.

    PubMed

    Ozer, Lale Meyancı; Ozer, Metin; Altındal, Ahmet; Ozkaya, Ali Rıza; Salih, Bekir; Bekaroğlu, Ozer

    2013-05-14

    The synthesis of 4,4'-[6,6'-methylenebis (2-(2-(3,4-dicyanophenoxy)-5-methylbenzyl)-4-methyl-6,1-phenylene)] bis (oxy) diphthalonitrile 1 was achieved starting from 4-nitrophthalonitrile and 6,6'-methylenebis(2-(2-hydroxy-5-methylbenzyl)-4-methylphenol in DMF at 50 °C by the catalysis of K2CO3 under argon. The corresponding dimeric metallophthalocyanines (Zn2Pc2 2 and Co2Pc2 3) were tetramerized in dimethylaminoethanol with the appropriate metal salt. Newly synthesized compounds were characterized by elemental analysis, UV-vis, FT-IR (ATR), MALDI-TOF mass and (1)H-NMR spectroscopy techniques. The electrochemical properties of the complexes were examined by cyclic voltammetry, differential pulse voltammetry, controlled potential coulometry and in situ spectroelectrochemistry in nonaqueous media. The results showed that while there is considerable weak interactions between the two metal phthalocyanine units in dimeric zinc phthalocyanine, these interactions in dimeric cobalt phthalocyanine is remarkable. The catalytic performances of dimeric cobalt phthalocyanine in the reduction of oxygen in a medium similar to the working conditions of the polymer electrolyte membrane fuel-cells were found to be much higher than that of dinuclear zinc phthalocyanine. Solution-processed films of the complexes were utilized as an active semiconducting layer in the fabrication of organic field-effect transistors (OFETs) in the bottom-gate configurations. The output characteristics of the resulting p-type OFET devices were investigated to evaluate the performances such as the field effect mobility (μF). A relatively high field effect mobility of 7.3 × 10(-3) cm(2) V(-1) s(-1) was observed for dimeric cobalt phthalocyanine.

  16. Radiation-enhanced optical antenna based on nonperiodic metallic nanoparticle dimer chain

    NASA Astrophysics Data System (ADS)

    Chen, Xiaolin; Yu, Wenhai; Yue, Wencheng; Yao, Peijun; Liu, Wen

    2015-07-01

    With the aid of multi-sphere dyadic Green's function, we present a design of optical nanoantenna which is composed of a nonperiodic nanoparticle dimer chain. By breaking the periodicity of the dimer chain, the radiative emission of the dimer chain is significantly enhanced because the strong coupling which limits radiation enhancement is inhibited when the separations between dimers are reduced. Our work clearly shows the crucial role of nonperiodicity in the design of the Yagi-Uda nanoantenna.

  17. Dimeric States of Neural- and Epithelial-Cadherins are Distinguished by the Rate of Disassembly†

    PubMed Central

    Vunnam, Nagamani; Flint, Jon; Balbo, Andrea; Schuck, Peter; Pedigo, Susan

    2011-01-01

    Epithelial- and Neural-cadherins are specifically localized at synapses in neurons which can change shape and contact surface on a time scale of seconds to months. We have focused our studies on the role of the extracellular domains of cadherins in the dynamics of synapses. The kinetics of dimer disassembly of the first two extracellular domains of E- and N-cadherin, ECAD12 and NCAD12, were studied with analytical size exclusion chromatography and sedimentation velocity. NCAD12 forms three different dimers that are distinguished by assembly conditions and kinetics of dissociation. ECAD12 dimer disassembles rapidly regardless of the calcium concentration, whereas the disassembly of NCAD12 dimers was strongly dependent on calcium concentration. In addition to the apo- and saturated-dimeric forms of NCAD12, there is a third dimeric form that is a slow exchange dimer. This third dimeric form for NCAD12, formed by decalcification of the calcium-saturated dimer, was kinetically-trapped in apo-conditions and did not disassemble over a period of months. Sedimentation velocity experiments showed that this dimer, upon addition of calcium, had similar weighted averages as calcium-saturated dimer. These studies provide evidence that the kinetics of dimer disassembly of the extracellular domains may be a major contributor to the morphological dynamics of synapses in vivo. PMID:21375242

  18. 40 CFR 721.9484 - Dimer acid/rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Dimer acid/rosin amidoamine reaction... Specific Chemical Substances § 721.9484 Dimer acid/rosin amidoamine reaction product (generic). (a... generically as Dimer acid/rosin amidoamine reaction product (PMN P-99-0143) is subject to reporting under...

  19. 40 CFR 721.9484 - Dimer acid/rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Dimer acid/rosin amidoamine reaction... Specific Chemical Substances § 721.9484 Dimer acid/rosin amidoamine reaction product (generic). (a... generically as Dimer acid/rosin amidoamine reaction product (PMN P-99-0143) is subject to reporting under...

  20. 40 CFR 721.9484 - Dimer acid/rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Dimer acid/rosin amidoamine reaction... Specific Chemical Substances § 721.9484 Dimer acid/rosin amidoamine reaction product (generic). (a... generically as Dimer acid/rosin amidoamine reaction product (PMN P-99-0143) is subject to reporting under...

  1. 40 CFR 721.9484 - Dimer acid/rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Dimer acid/rosin amidoamine reaction... Specific Chemical Substances § 721.9484 Dimer acid/rosin amidoamine reaction product (generic). (a... generically as Dimer acid/rosin amidoamine reaction product (PMN P-99-0143) is subject to reporting under...

  2. 40 CFR 721.9484 - Dimer acid/rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Dimer acid/rosin amidoamine reaction... Specific Chemical Substances § 721.9484 Dimer acid/rosin amidoamine reaction product (generic). (a... generically as Dimer acid/rosin amidoamine reaction product (PMN P-99-0143) is subject to reporting under...

  3. Evaluation of stability difference between asymmetric homochiral dimer in (S)-thalidomide crystal and symmetric heterochiral dimer in (RS)-thalidomide crystal

    NASA Astrophysics Data System (ADS)

    Suzuki, Toshiya; Tanaka, Masahito; Shiro, Motoo; Shibata, Norio; Osaka, Tetsuya; Asahi, Toru

    2010-03-01

    This article discusses differences in physicochemical properties such as solubility and melting point between (S)-thalidomide and (RS)-thalidomide based on crystal structures determined by X-ray diffraction experiments. Investigation of such differences is of great importance because thalidomide has attracted considerable attention again due to its wide-range bioactivity for intractable diseases. In this article, structures of hydrogen-bonded rings were compared between asymmetric homochiral dimers in (S)-thalidomide crystal and symmetric heterochiral dimers in (RS)-thalidomide crystal. The heterochiral dimer was evaluated to be more stable than the homochiral dimer by the energy calculations for hydrogen-bonded rings in those dimers. These results indicate that differences in physicochemical properties between enantiomeric and racemic thalidomides originate from the difference of structural stability between homochiral and heterochiral dimers.

  4. Magnitude and orientation dependence of intermolecular interaction of perfluoropropane dimer studied by high-level ab initio calculations: Comparison with propane dimer

    NASA Astrophysics Data System (ADS)

    Tsuzuki, Seiji; Uchimaru, Tadafumi; Mikami, Masuhiro; Urata, Shingo

    2004-11-01

    Intermolecular interaction energies of 12 orientations of C3F8 dimers were calculated with electron correlation correction by the second-order Møller-Plesset perturbation method. The antiparallel C2h dimer has the largest interaction energy (-1.45 kcal/mol). Electron correlation correction increases the attraction considerably. Electrostatic energy is not large. Dispersion is mainly responsible for the attraction. Orientation dependence of the interaction energy of the C3F8 dimer is substantially smaller than that of the C3H8 dimer. The calculated interaction energy of the C3F8 dimer at the potential minimum is 78% of that of the C3H8 dimer (-1.85 kcal/mol), whereas the interaction energies of the CF4 and C2F6 dimers are larger than those of the CH4 and C2H6 dimers. The intermolecular separation in the C3F8 dimer at the potential minimum is substantially larger than that in the C3H8 dimer. The larger intermolecular separation due to the steric repulsion between fluorine atoms is the cause of the smaller interaction energy of the C3F8 dimer at the potential minimum. The calculated intermolecular interaction energy potentials of the C3F8 dimers using an all atom model OPLS-AA (OPLS all atom model) force field and a united atom model force field were compared with the ab initio calculations. Although the two force fields well reproduces the experimental vapor and liquid properties of perfluoroalkenes, the comparison shows that the united atom model underestimates the potential depth and orientation dependence of the interaction energy. The potentials obtained by the OPLS-AA force field are close to those obtained by the ab initio calculations.

  5. An algebra of dimerization and its implications for G-protein coupled receptor signaling.

    PubMed

    Woolf, Peter J; Linderman, Jennifer J

    2004-07-21

    Many species of receptors form dimers, but how can we use this information to make predictions about signal transduction? This problem is particularly difficult when receptors dimerize with many different species, leading to a combinatoric increase in the possible number of dimer pairs. As an example system, we focus on receptors in the G-protein coupled receptor (GPCR) family. GPCRs have been shown to reversibly form dimers, but this dimerization does not directly affect signal transduction. Here we present a new theoretical framework called a dimerization algebra. This algebra provides a systematic and rational way to represent, manipulate, and in some cases simplify large and often complicated networks of dimerization interactions. To compliment this algebra, Monte Carlo simulations are used to predict dimerization's effect on receptor organization on the membrane, signal transduction, and internalization. These simulation results are directly comparable to various experimental measures such as fluorescence resonance energy transfer (FRET), and as such provide a link between the dimerization algebra and experimental data. As an example, we show how the algebra and computational results can be used to predict the effects of dimerization on the dopamine D2 and somatastatin SSTR1 receptors. When these predictions were compared to experimental findings from the literature, good agreement was found, demonstrating the utility of our approach. Applications of this work to the development of a novel class of dimerization-modulating drugs are also discussed.

  6. Mechanisms for kinase-mediated dimerization of the epidermal growth factor receptor.

    PubMed

    Lu, Chafen; Mi, Li-Zhi; Schürpf, Thomas; Walz, Thomas; Springer, Timothy A

    2012-11-02

    We study a mechanism by which dimerization of the EGF receptor (EGFR) cytoplasmic domain is transmitted to the ectodomain. Therapeutic and other small molecule antagonists to the kinase domain that stabilize its active conformation, but not those that stabilize an inactive conformation, stabilize ectodomain dimerization. Inhibitor-induced dimerization requires an asymmetric kinase domain interface associated with activation. EGF and kinase inhibitors stimulate formation of identical dimer interfaces in the EGFR transmembrane domain, as shown by disulfide cross-linking. Disulfide cross-linking at an interface in domain IV in the ectodomain was also stimulated similarly; however, EGF but not inhibitors stimulated cross-linking in domain II. Inhibitors similarly induced noncovalent dimerization in nearly full-length, detergent-solubilized EGFR as shown by gel filtration. EGFR ectodomain deletion resulted in spontaneous dimerization, whereas deletion of exons 2-7, in which extracellular domains III and IV are retained, did not. In EM, kinase inhibitor-induced dimers lacked any well defined orientation between the ectodomain monomers. Fab of the therapeutic antibody cetuximab to domain III confirmed a variable position and orientation of this domain in inhibitor-induced dimers but suggested that the C termini of domain IV of the two monomers were in close proximity, consistent with dimerization in the transmembrane domains. The results provide insights into the relative energetics of intracellular and extracellular dimerization in EGFR and have significance for physiologic dimerization through the asymmetric kinase interface, bidirectional signal transmission in EGFR, and mechanism of action of therapeutics.

  7. Intramolecular hydrophobic interactions are critical mediators of STAT5 dimerization.

    PubMed

    Fahrenkamp, Dirk; Li, Jinyu; Ernst, Sabrina; Schmitz-Van de Leur, Hildegard; Chatain, Nicolas; Küster, Andrea; Koschmieder, Steffen; Lüscher, Bernhard; Rossetti, Giulia; Müller-Newen, Gerhard

    2016-10-18

    STAT5 is an essential transcription factor in hematopoiesis, which is activated through tyrosine phosphorylation in response to cytokine stimulation. Constitutive activation of STAT5 is a hallmark of myeloid and lymphoblastic leukemia. Using homology modeling and molecular dynamics simulations, a model of the STAT5 phosphotyrosine-SH2 domain interface was generated providing first structural information on the activated STAT5 dimer including a sequence, for which no structural information is available for any of the STAT proteins. We identified a novel intramolecular interaction mediated through F706, adjacent to the phosphotyrosine motif, and a unique hydrophobic interface on the surface of the SH2 domain. Analysis of corresponding STAT5 mutants revealed that this interaction is dispensable for Epo receptor-mediated phosphorylation of STAT5 but essential for dimer formation and subsequent nuclear accumulation. Moreover, the herein presented model clarifies molecular mechanisms of recently discovered leukemic STAT5 mutants and will help to guide future drug development.

  8. Identities between dimer partition functions on different surfaces

    NASA Astrophysics Data System (ADS)

    Cimasoni, David; Pham, Anh Minh

    2016-10-01

    Given a weighted graph G embedded in a non-orientable surface Σ , one can consider the corresponding weighted graph \\widetilde{G} embedded in the so-called orientation cover \\widetildeΣ of Σ . We prove identities relating twisted partition functions of the dimer model on these two graphs. When Σ is the Möbius strip or the Klein bottle, then \\widetildeΣ is the cylinder or the torus, respectively, and under some natural assumptions, these identities imply relations between the genuine dimer partition functions Z(G) and Z(\\widetilde{G}) . For example, we show that if G is a locally but not globally bipartite graph embedded in the Möbius strip, then Z(\\widetilde{G}) is equal to the square of Z(G). This extends results for the square lattice previously obtained by various authors.

  9. Microwave Spectrum of the Ethanol-Methanol Dimer

    NASA Astrophysics Data System (ADS)

    Finneran, Ian A.; Carroll, Brandon; Mead, Griffin; Blake, Geoffrey

    2016-06-01

    The hydrogen bond donor/acceptor competition in mixed alcohol clusters remains a fundamental question in physical chemistry. Previous theoretical work on the prototype ethanol-methanol dimer has been inconclusive in predicting the energetically preferred structure. Here, we report the microwave spectrum of the ethanol-methanol dimer between 8-18 GHz, using a chirped pulse Fourier transform microwave spectrometer. With the aid of ab initio calculations, 36 transitions have been fit and assigned to a t-ethanol-acceptor, methanol-donor structure in an argon-backed expansion. In a helium-backed expansion, a second excited conformer has been observed, and tentatively assigned to a g-ethanol-acceptor, methanol-donor structure. No ethanol-donor, methanol-acceptor structures have been found, suggesting such structures are energetically disfavored.

  10. Single nucleotide polymorphism analysis using different colored dye dimer probes

    NASA Astrophysics Data System (ADS)

    Marmé, Nicole; Friedrich, Achim; Denapaite, Dalia; Hakenbeck, Regine; Knemeyer, Jens-Peter

    2006-09-01

    Fluorescence quenching by dye dimer formation has been utilized to develop hairpin-structured DNA probes for the detection of a single nucleotide polymorphism (SNP) in the penicillin target gene pbp2x, which is implicated in the penicillin resistance of Streptococcus pneumoniae. We designed two specific DNA probes for the identification of the pbp2x genes from a penicillin susceptible strain R6 and a resistant strain Streptococcus mitis 661 using green-fluorescent tetramethylrhodamine (TMR) and red-fluorescent DY-636, respectively. Hybridization of each of the probes to its respective target DNA sequence opened the DNA hairpin probes, consequently breaking the nonfluorescent dye dimers into fluorescent species. This hybridization of the target with the hairpin probe achieved single nucleotide specific detection at nanomolar concentrations via increased fluorescence.

  11. Hydrogen bonding in the benzene-ammonia dimer

    NASA Technical Reports Server (NTRS)

    Rodham, David A.; Suzuki, Sakae; Suenram, Richard D.; Lovas, Frank J.; Dasgupta, Siddharth; Goddard, William A., III; Blake, Geoffrey A.

    1993-01-01

    High-resolution optical and microwave spectra of the gas-phase benzene-ammonia dimer were obtained, showing that the ammonia molecule resides above the benzene plane and undergoes free, or nearly free, internal rotation. To estimate the binding energy (De) and other global properties of the intermolecular potential, theoretical calculations were performed for the benzene-ammonia dimer, using the Gaussian 92 (Fritsch, 1992) program at the MP2/6-31G** level. The predicted De was found to be at the lowest end of the range commonly accepted for hydrogen bonding and considerably below that of C6H6-H2O, consistent with the gas-phase acidities of ammonia and water. The observed geometry greatly resembles the amino-aromatic interaction found naturally in proteins.

  12. Monomeric and dimeric hydrolysable tannins of Tamarix nilotica.

    PubMed

    Orabi, Mohamed A A; Taniguchi, Shoko; Hatano, Tsutomu

    2009-07-01

    An ellagitannin monomer, nilotinin M1 (1), and three dimers, nilotinins D1 (2), D2 (3), and D3 (4), were isolated from leaves of Tamarix nilotica (Ehrenb.) Bunge. Structures were elucidated based on analysis of spectroscopic data and chemical correlations with known compounds. In addition, six known tannins, hirtellin A (5) (dimer), remurin A (6), remurin B (7), 1,3-di-O-galloyl-4,6-O-(S)-hexahydroxydiphenoyl-beta-D-glucose (8), gemin D (9), and hippomanin A (10) (monomers), were isolated for the first time from this plant species. The reported (13)C NMR assignments of the dehydrodigalloyl moiety and glucose cores of 5 are revised, and the (13)C NMR spectroscopic data for 6 and 7 are also reported for the first time.

  13. Intramolecular hydrophobic interactions are critical mediators of STAT5 dimerization

    NASA Astrophysics Data System (ADS)

    Fahrenkamp, Dirk; Li, Jinyu; Ernst, Sabrina; Schmitz-van de Leur, Hildegard; Chatain, Nicolas; Küster, Andrea; Koschmieder, Steffen; Lüscher, Bernhard; Rossetti, Giulia; Müller-Newen, Gerhard

    2016-10-01

    STAT5 is an essential transcription factor in hematopoiesis, which is activated through tyrosine phosphorylation in response to cytokine stimulation. Constitutive activation of STAT5 is a hallmark of myeloid and lymphoblastic leukemia. Using homology modeling and molecular dynamics simulations, a model of the STAT5 phosphotyrosine-SH2 domain interface was generated providing first structural information on the activated STAT5 dimer including a sequence, for which no structural information is available for any of the STAT proteins. We identified a novel intramolecular interaction mediated through F706, adjacent to the phosphotyrosine motif, and a unique hydrophobic interface on the surface of the SH2 domain. Analysis of corresponding STAT5 mutants revealed that this interaction is dispensable for Epo receptor-mediated phosphorylation of STAT5 but essential for dimer formation and subsequent nuclear accumulation. Moreover, the herein presented model clarifies molecular mechanisms of recently discovered leukemic STAT5 mutants and will help to guide future drug development.

  14. Fermion fractionalization to Majorana fermions in a dimerized Kitaev superconductor

    NASA Astrophysics Data System (ADS)

    Wakatsuki, Ryohei; Ezawa, Motohiko; Tanaka, Yukio; Nagaosa, Naoto

    2014-07-01

    We study theoretically a one-dimensional dimerized Kitaev superconductor model which belongs to BDI class with time-reversal, particle-hole, and chiral symmetries. There are two sources of the particle-hole symmetry, i.e., the sublattice symmetry and superconductivity. Accordingly, we define two types of topological numbers with respect to the chiral indices of normal and Majorana fermions, which offers an ideal laboratory to examine the interference between the two different physics within the same symmetry class. Phase diagram, zero-energy bound states, and conductance at normal metal/superconductor junction of this model are unveiled from this viewpoint. Especially, the electron fractionalization to the Majorana fermions showing the splitting of the local density of states is realized at the soliton of the dimerization in this model.

  15. Fermion Fractionalization to Majorana Fermions in Dimerized Kitaev Superconductor

    NASA Astrophysics Data System (ADS)

    Wakatsuki, Ryohei; Ezawa, Motohiko; Tanaka, Yukio; Nagaosa, Naoto

    2015-03-01

    We study theoretically a one-dimensional dimerized Kitaev superconductor model which belongs to BDI class with time-reversal, particle-hole, and chiral symmetries. There are two sources of the particle-hole symmetry, i.e., the sublattice symmetry and superconductivity. Accordingly, we define two types of topological numbers with respect to the chiral indices of normal and Majorana fermions, which offers an ideal laboratory to examine the interference between the two different physics within the same symmetry class. Phase diagram, zero-energy bound states, and conductance at normal metal/superconductor junction of this model are unveiled from this viewpoint. Especially, the electron fractionalization to the Majorana fermions showing the splitting of the local density of states is realized at the soliton of the dimerization in this model.

  16. Self-assembly of dimeric tetraurea calix[4]pyrrole capsules

    PubMed Central

    Ballester, Pablo; Gil-Ramírez, Guzmán

    2009-01-01

    Calix[4]pyrroles having extended aromatic cavities have been functionalized with 4 ureas in the para position of their meso phenyl substituents. This elaboration of the upper rim was completed in 2 synthetic steps starting from the α,α,α,α-tetranitro isomer of the calix[4]pyrrole obtained in the acid catalyzed condensation of p-nitrophenyl methyl ketone and pyrrole. In dichloromethane solution and in the presence of 4,4′-bipyridine N-N′-dioxide the tetraurea calix[4]pyrrole dimerizes reversibly forming a cyclic array of 16 hydrogen bonds and encapsulating 1 molecule of bis-N-oxide. The encapsulated guest is bound in the cavity by hydrogen bonding to the 2 endohedral calix[4]pyrrole centers. Further evidence for dimerization of the tetraurea calix[4]pyrroles is provided by 1H-NMR experiments and by the formation of mixed capsules. PMID:19261848

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

    PubMed

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

    2014-11-15

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

  18. UV resonance Raman analysis of trishomocubane and diamondoid dimers

    SciTech Connect

    Meinke, Reinhard Thomsen, Christian; Maultzsch, Janina; Richter, Robert; Merli, Andrea; Fokin, Andrey A.; Koso, Tetyana V.; Schreiner, Peter R.; Rodionov, Vladimir N.

    2014-01-21

    We present resonance Raman measurements of crystalline trishomocubane and diamantane dimers containing a C=C double bond. Raman spectra were recorded with excitation energies between 2.33 eV and 5.42 eV. The strongest enhancement is observed for the C=C stretch vibration and a bending mode involving the two carbon atoms of the C=C bond, corresponding to the B{sub 2g} wagging mode of ethylene. This is associated with the localization of the π-HOMO and LUMO and the elongation of the C=C bond length and a pyramidalization of the two sp{sup 2}-hybridized carbon atoms at the optical excitation. The observed Raman resonance energies of the trishomocubane and diamantane dimers are significantly lower than the HOMO-LUMO gaps of the corresponding unmodified diamondoids.

  19. Antioxidant Properties of Aminoethylcysteine Ketimine Decarboxylated Dimer: A Review

    PubMed Central

    Macone, Alberto; Fontana, Mario; Barba, Marco; Botta, Bruno; Nardini, Mirella; Ghirga, Francesca; Calcaterra, Andrea; Pecci, Laura; Matarese, Rosa Marina

    2011-01-01

    Aminoethylcysteine ketimine decarboxylated dimer is a natural sulfur-containing compound detected in human plasma and urine, in mammalian brain and in many common edible vegetables. Over the past decade many studies have been undertaken to identify its metabolic role. Attention has been focused on its antioxidant properties and on its reactivity against oxygen and nitrogen reactive species. These properties have been studied in different model systems starting from plasma lipoproteins to specific cellular lines. All these studies report that aminoethylcysteine ketimine decarboxylated dimer is able to interact both with reactive oxygen and nitrogen species (hydrogen peroxide, superoxide anion, hydroxyl radical, peroxynitrite and its derivatives). Its antioxidant activity is similar to that of Vitamin E while higher than other hydrophilic antioxidants, such as trolox and N-acetylcysteine. PMID:21686170

  20. Inhibition of HIV-1 Reverse Transcriptase Dimerization by Small Molecules.

    PubMed

    Tintori, Cristina; Corona, Angela; Esposito, Francesca; Brai, Annalaura; Grandi, Nicole; Ceresola, Elisa Rita; Clementi, Massimo; Canducci, Filippo; Tramontano, Enzo; Botta, Maurizio

    2016-04-15

    Because HIV-1 reverse transcriptase is an enzyme whose catalytic activity depends on its heterodimeric structure, this system could be a target for inhibitors that perturb the interactions between the protein subunits, p51 and p66. We previously demonstrated that the small molecule MAS0 reduced the association of the two RT subunits and simultaneously inhibited both the polymerase and ribonuclease H activities. In this study, some analogues of MAS0 were rationally selected by docking studies and evaluated in vitro for their ability to disrupt dimeric assembly. Two inhibitors were identified with improved activity compared to MAS0. This study lays the basis for the rational design of more potent inhibitors of RT dimerization.

  1. UV resonance Raman analysis of trishomocubane and diamondoid dimers.

    PubMed

    Meinke, Reinhard; Richter, Robert; Merli, Andrea; Fokin, Andrey A; Koso, Tetyana V; Rodionov, Vladimir N; Schreiner, Peter R; Thomsen, Christian; Maultzsch, Janina

    2014-01-21

    We present resonance Raman measurements of crystalline trishomocubane and diamantane dimers containing a C=C double bond. Raman spectra were recorded with excitation energies between 2.33 eV and 5.42 eV. The strongest enhancement is observed for the C=C stretch vibration and a bending mode involving the two carbon atoms of the C=C bond, corresponding to the B2g wagging mode of ethylene. This is associated with the localization of the π-HOMO and LUMO and the elongation of the C=C bond length and a pyramidalization of the two sp(2)-hybridized carbon atoms at the optical excitation. The observed Raman resonance energies of the trishomocubane and diamantane dimers are significantly lower than the HOMO-LUMO gaps of the corresponding unmodified diamondoids.

  2. Intramolecular hydrophobic interactions are critical mediators of STAT5 dimerization

    PubMed Central

    Fahrenkamp, Dirk; Li, Jinyu; Ernst, Sabrina; Schmitz-Van de Leur, Hildegard; Chatain, Nicolas; Küster, Andrea; Koschmieder, Steffen; Lüscher, Bernhard; Rossetti, Giulia; Müller-Newen, Gerhard

    2016-01-01

    STAT5 is an essential transcription factor in hematopoiesis, which is activated through tyrosine phosphorylation in response to cytokine stimulation. Constitutive activation of STAT5 is a hallmark of myeloid and lymphoblastic leukemia. Using homology modeling and molecular dynamics simulations, a model of the STAT5 phosphotyrosine-SH2 domain interface was generated providing first structural information on the activated STAT5 dimer including a sequence, for which no structural information is available for any of the STAT proteins. We identified a novel intramolecular interaction mediated through F706, adjacent to the phosphotyrosine motif, and a unique hydrophobic interface on the surface of the SH2 domain. Analysis of corresponding STAT5 mutants revealed that this interaction is dispensable for Epo receptor-mediated phosphorylation of STAT5 but essential for dimer formation and subsequent nuclear accumulation. Moreover, the herein presented model clarifies molecular mechanisms of recently discovered leukemic STAT5 mutants and will help to guide future drug development. PMID:27752093

  3. Association of atoms into universal dimers using an oscillating magnetic field.

    PubMed

    Langmack, Christian; Smith, D Hudson; Braaten, Eric

    2015-03-13

    In a system of ultracold atoms near a Feshbach resonance, pairs of atoms can be associated into universal dimers by an oscillating magnetic field with a frequency near that determined by the dimer binding energy. We present a simple expression for the transition rate that takes into account many-body effects through a transition matrix element of the contact. In a thermal gas, the width of the peak in the transition rate as a function of the frequency is determined by the temperature. In a dilute Bose-Einstein condensate of atoms, the width is determined by the inelastic scattering rates of a dimer with zero-energy atoms. Near an atom-dimer resonance, there is a dramatic increase in the width from inelastic atom-dimer scattering and from atom-atom-dimer recombination. The recombination contribution provides a signature for universal tetramers that are Efimov states consisting of two atoms and a dimer.

  4. D-dimer: An Overview of Hemostasis and Fibrinolysis, Assays, and Clinical Applications.

    PubMed

    Olson, John D

    2015-01-01

    D-dimer is the smallest fibrinolysis-specific degradation product found in the circulation. The origins, assays, and clinical use of D-dimer will be addressed. Hemostasis (platelet and vascular function, coagulation, fibrinolysis, hemostasis) is briefly reviewed. D-dimer assays are reviewed. The D-dimer is very sensitive to intravascular thrombus and may be markedly elevated in disseminated intravascular coagulation, acute aortic dissection, and pulmonary embolus. Because of its exquisite sensitivity, negative tests are useful in the exclusion venous thromboembolism. Elevations occur in normal pregnancy, rising two- to fourfold by delivery. D-dimer also rises with age, limiting its use in those >80 years old. There is a variable rise in D-dimer in active malignancy and indicates increased thrombosis risk in active disease. Elevated D-dimer following anticoagulation for a thrombotic event indicates increased risk of recurrent thrombosis. These and other issues are addressed.

  5. Conformational Heterogeneity of Bax Helix 9 Dimer for Apoptotic Pore Formation

    NASA Astrophysics Data System (ADS)

    Liao, Chenyi; Zhang, Zhi; Kale, Justin; Andrews, David W.; Lin, Jialing; Li, Jianing

    2016-07-01

    Helix α9 of Bax protein can dimerize in the mitochondrial outer membrane (MOM) and lead to apoptotic pores. However, it remains unclear how different conformations of the dimer contribute to the pore formation on the molecular level. Thus we have investigated various conformational states of the α9 dimer in a MOM model — using computer simulations supplemented with site-specific mutagenesis and crosslinking of the α9 helices. Our data not only confirmed the critical membrane environment for the α9 stability and dimerization, but also revealed the distinct lipid-binding preference of the dimer in different conformational states. In our proposed pathway, a crucial iso-parallel dimer that mediates the conformational transition was discovered computationally and validated experimentally. The corroborating evidence from simulations and experiments suggests that, helix α9 assists Bax activation via the dimer heterogeneity and interactions with specific MOM lipids, which eventually facilitate proteolipidic pore formation in apoptosis regulation.

  6. Multiple-charge transfer and trapping in DNA dimers

    NASA Astrophysics Data System (ADS)

    Tornow, Sabine; Bulla, Ralf; Anders, Frithjof B.; Zwicknagl, Gertrud

    2010-11-01

    We investigate the charge transfer characteristics of one and two excess charges in a DNA base-pair dimer using a model Hamiltonian approach. The electron part comprises diagonal and off-diagonal Coulomb matrix elements such a correlated hopping and the bond-bond interaction, which were recently calculated by Starikov [E. B. Starikov, Philos. Mag. Lett. 83, 699 (2003)10.1080/0950083031000151374] for different DNA dimers. The electronic degrees of freedom are coupled to an ohmic or a superohmic bath serving as dissipative environment. We employ the numerical renormalization group method in the nuclear tunneling regime and compare the results to Marcus theory for the thermal activation regime. For realistic parameters, the rate that at least one charge is transferred from the donor to the acceptor in the subspace of two excess electrons significantly exceeds the rate in the single charge sector. Moreover, the dynamics is strongly influenced by the Coulomb matrix elements. We find sequential and pair transfer as well as a regime where both charges remain self-trapped. The transfer rate reaches its maximum when the difference of the on-site and intersite Coulomb matrix element is equal to the reorganization energy which is the case in a guanine/cytosine (GC)-dimer. Charge transfer is completely suppressed for two excess electrons in adenine/thymine (AT)-dimer in an ohmic bath and replaced by damped coherent electron-pair oscillations in a superohmic bath. A finite bond-bond interaction W alters the transfer rate: it increases as function of W when the effective Coulomb repulsion exceeds the reorganization energy (inverted regime) and decreases for smaller Coulomb repulsion.

  7. A new hydroxychavicol dimer from the roots of Piper betle.

    PubMed

    Lin, Chwan-Fwu; Hwang, Tsong-Long; Chien, Chun-Chien; Tu, Huei-Yu; Lay, Horng-Liang

    2013-02-26

    A new hydroxychavicol dimer, 2-(g'-hydroxychavicol)-hydroxychavicol (1), was isolated from the roots of Piper betle Linn. along with five known compounds, hydroxychavicol (2), aristololactam A II (3), aristololactam B II (4), piperolactam A (5) and cepharadione A (6). The structures of these isolated compounds were elucidated by spectroscopic methods. Compounds 1 and 2 exhibited inhibitory effects on the generation of superoxide anion and the release of elastase by human neutrophils.

  8. Monitoring Retroviral RNA Dimerization In Vivo via Hammerhead Ribozyme Cleavage

    PubMed Central

    Pal, Bijay K.; Scherer, Lisa; Zelby, Laurie; Bertrand, Edouard; Rossi, John J.

    1998-01-01

    We have used a strategy for colocalization of Psi (Ψ)-tethered ribozymes and targets to demonstrate that Ψ sequences are capable of specific interaction in the cytoplasm of both packaging and nonpackaging cells. These results indicate that current in vitro dimerization models may have in vivo counterparts. The methodology used may be applied to further genetic analyses on Ψ domain interactions in vivo. PMID:9733882

  9. Unexpected methyl migrations of ethanol dimer under synchrotron VUV radiation.

    PubMed

    Xiao, Weizhan; Hu, Yongjun; Li, Weixing; Guan, Jiwen; Liu, Fuyi; Shan, Xiaobin; Sheng, Liusi

    2015-01-14

    While methyl transfer is well known to occur in the enzyme- and metal-catalyzed reactions, the methyl transfer in the metal-free organic molecules induced by the photon ionization has been less concerned. Herein, vacuum ultraviolet single photon ionization and dissociation of ethanol dimer are investigated with synchrotron radiation photoionization mass spectroscopy and theoretical methods. Besides the protonated clusters cation (C2H5OH)⋅H(+) (m/z = 47) and the β-carbon-carbon bond cleavage fragment CH2O⋅(C2H5OH)H(+) (m/z = 77), the measured mass spectra revealed that a new fragment (C2H5OH)⋅(CH3)(+) (m/z = 61) appeared at the photon energy of 12.1 and 15.0 eV, where the neutral dimer could be vertically ionized to higher ionic state. Thereafter, the generated carbonium ions are followed by a Wagner-Meerwein rearrangement and then dissociate to produce this new fragment, which is considered to generate after surmounting a few barriers including intra- and inter-molecular methyl migrations by the aid of theoretical calculations. The appearance energy of this new fragment is measured as 11.55 ± 0.05 eV by scanning photoionization efficiency curve. While the signal intensity of fragment m/z = 61 starts to increase, the fragments m/z = 47 and 77 tend to slowly incline around 11.55 eV photon energy. This suggests that the additional fragment channels other than (C2H5OH)⋅H(+) and CH2O⋅(C2H5OH)H(+) have also been opened, which consume some dimer cations. The present report provides a clear description of the photoionization and dissociation processes of the ethanol dimer in the range of the photon energy 12-15 eV.

  10. Iron-Catalyzed gem-Specific Dimerization of Terminal Alkynes.

    PubMed

    Liang, Qiuming; Osten, Kimberly M; Song, Datong

    2017-03-13

    We report a gem-specific homo- and cross-dimerization of terminal alkynes catalyzed by a well-defined iron(II) complex containing Cp* and picolyl N-heterocyclic carbene (NHC) ligands, and featuring a piano-stool structure. This catalytic system requires no additives and is compatible with a broad range of substrates, including those with polar functional groups such as NH and OH.

  11. Plasmon excitations in the dimers formed by atom chains

    NASA Astrophysics Data System (ADS)

    Xue, Hong-jie; Hao, Da-peng; Zhang, Ming; Wang, Xiao-mei

    2017-02-01

    Based on the linear response theory in the random-phase approximation and the free-electron gas model, we study the plasmon excitations in the dimers formed by atom chains. With the help of energy absorption spectrum and charge distribution, the evolutions of longitudinal and transverse plasmon, and the effect of the system parameters such as size, atomic separation and electron filling on plasmon are obtained. In addition, the dipole, quadrupole, end and central plasmon are observed.

  12. Nonlinear optical response of cofacial phthalocyanine dimers and trimers

    SciTech Connect

    Manas, E.S.; Spano, F.C.; Chen, L.X.

    1997-07-01

    The effects of intermacrocycle interactions on the second hyperpolarizabilities {l_angle}{gamma}({minus}{omega};{omega},{minus}{omega},{omega}){r_angle} of cofacial phthalocyanine dimers and trimers are studied. A theoretical analysis is presented based on the Frenkel exciton model for a chain of three level molecules. Using a simplified analysis in the static and near-resonant regimes we identify two mechanisms which lead to enhancements in the dimer or trimer value of {l_angle}{gamma}({minus}{omega};{omega},{minus}{omega},{omega}){r_angle} over that of the monomer. The first mechanism is a disruption of the balance between type I and type II terms in the sum over states expression for the second hyperpolarizability tensor {gamma}{sub kjih}({minus}{omega};{omega},{minus}{omega},{omega}), caused by weak intermacrocycle interactions. The second is a near-resonance enhancement of the type II terms due to an intermacrocycle interaction induced shift in the monomer derived two-photon allowed states towards twice the laser photon energy. This analysis is in good agreement with recent degenerate four wave mixing experiments [SPIE Proc. {bold 2527}, 61 (1995)] which showed a strong enhancement of {l_angle}{gamma}({minus}{omega};{omega},{minus}{omega},{omega}){r_angle} for SiPcO oligomers as a function of the number of macrocycles. Our calculations suggest that the first mechanism is responsible for the 25-fold monomer to dimer enhancement measured in this system, and that the additional 4-fold enhancement found in going from the dimer to the trimer is primarily the result of the second mechanism. {copyright} {ital 1997 American Institute of Physics.}

  13. Excited State Pathways Leading to Formation of Adenine Dimers.

    PubMed

    Banyasz, Akos; Martinez-Fernandez, Lara; Ketola, Tiia-Maaria; Muñoz-Losa, Aurora; Esposito, Luciana; Markovitsi, Dimitra; Improta, Roberto

    2016-06-02

    The reaction intermediate in the path leading to UV-induced formation of adenine dimers A═A and AA* is identified for the first time quantum mechanically, using PCM/TD-DFT calculations on (dA)2 (dA: 2'deoxyadenosine). In parallel, its fingerprint is detected in the absorption spectra recorded on the millisecond time-scale for the single strand (dA)20 (dA: 2'deoxyadenosine).

  14. A DFT study of substituent effects in corannulene dimers.

    PubMed

    Josa, Daniela; Rodríguez Otero, Jesús; Cabaleiro Lago, Enrique M

    2011-12-21

    Corannulene dimers made up of corannulene monomers with different curvature and substituents were studied using M06-2X, B97D and ωB97XD functionals and 6-31+G* basis set. Corannulene molecules were substituted with five alternating Br, Cl, CH(3), C(2)H or CN units. Geometric results showed that substituents gave rise to small changes in the curvature of corannulene bowls. So, there was not a clear relationship between the curvature of bowls and the changes on interaction energy generated by addition of substituents in the bowl. Electron withdrawing substituents gave rise to a more positive molecular electrostatic potential (MEP) of the bowl, which was able to get a strong interaction with the negative MEP at the surface of a fullerene. Substitution with CN caused the largest effect, giving rise to the most positive MEP and to a large interaction energy of -24.64 kcal mol(-1), at the ωB97XD/6-31+G* level. Dispersive effects must be taken into account to explain the catching ability of the different substituted corannulenes. For unsubstituted dimers, calculations with DFT-D methods employing ωB97XD and B97D functionals led to similar results to those previously reported at the SCS-MP2/cc-pVTZ level for corannulene dimers (A. Sygula and S. Saebø, Int. J. Quant. Chem., 2009, 109, 65). In particular, the ωB97XD functional led to a difference of only 0.35 kcal mol(-1), regarding MP2 interaction energy for corannulene dimers. On the other hand, the M06-2X functional showed a general considerable underestimation of interaction energies. This functional worked quite well to study trends, but not to obtain absolute interaction energies.

  15. Subunit interface mutants of rabbit muscle aldolase form active dimers.

    PubMed Central

    Beernink, P. T.; Tolan, D. R.

    1994-01-01

    We report the construction of subunit interface mutants of rabbit muscle aldolase A with altered quaternary structure. A mutation has been described that causes nonspherocytic hemolytic anemia and produces a thermolabile aldolase (Kishi H et al., 1987, Proc Natl Acad Sci USA 84:8623-8627). The disease arises from substitution of Gly for Asp-128, a residue at the subunit interface of human aldolase A. To elucidate the role of this residue in the highly homologous rabbit aldolase A, site-directed mutagenesis is used to replace Asp-128 with Gly, Ala, Asn, Gln, or Val. Rabbit aldolase D128G purified from Escherichia coli is found to be similar to human D128G by kinetic analysis, CD, and thermal inactivation assays. All of the mutant rabbit aldolases are similar to the wild-type rabbit enzyme in secondary structure and kinetic properties. In contrast, whereas the wild-type enzyme is a tetramer, chemical crosslinking and gel filtration indicate that a new dimeric species exists for the mutants. In sedimentation velocity experiments, the mutant enzymes as mixtures of dimer and tetramer at 4 degrees C. Sedimentation at 20 degrees C shows that the mutant enzymes are > 99.5% dimeric and, in the presence of substrate, that the dimeric species is active. Differential scanning calorimetry demonstrates that Tm values of the mutant enzymes are decreased by 12 degrees C compared to wild-type enzyme. The results indicate that Asp-128 is important for interface stability and suggest that 1 role of the quaternary structure of aldolase is to provide thermostability. PMID:7833800

  16. Purification and characterization of dimeric dihydrodiol dehydrogenase from dog liver.

    PubMed

    Sato, K; Nakanishi, M; Deyashiki, Y; Hara, A; Matsuura, K; Ohya, I

    1994-09-01

    High NADP(+)-linked dihydrodiol dehydrogenase activity was detected in dog liver cytosol, from which a dimeric enzyme composed of M(r) 39,000 subunits was purified to homogeneity. The enzyme oxidized trans-cyclohexanediol, and trans-dihydrodiols of benzene and naphthalene, the [1R,2R]-isomers of which were selectively oxidized. In the reverse reaction in the presence of NADPH as a coenzyme, the enzyme reduced alpha-dicarbonyl compounds, such as methylglyoxal, 3-deoxyglucosone, and diacetyl, and some compounds with a carbonyl group, such as glyceraldehyde, lactaldehyde, and acetoin. 4-Hydroxyphenylketones and ascorbates inhibited the enzyme. The results of steady-state kinetic analyses indicated that the reaction proceeds through an ordered bi bi mechanism with the coenzyme binding to the free enzyme, and suggested that the inhibitors bind to the enzyme-NADP+ binary complex. The dimeric enzyme was detected in liver and kidney of dog, and was immunochemically similar to the dimeric enzymes from monkey kidney, rabbit lens, and pig liver. The sequences (total 127 amino acid residues) of eight peptides derived on enzymatic digestion of the dog liver enzyme did not show significant similarity with the primary structures of members of the aldo-keto reductase and short chain dehydrogenase superfamilies, which include monomeric dihydrodiol dehydrogenases and carbonyl reductase, respectively.

  17. Formation of Enhanced Uniform Chiral Fields in Symmetric Dimer Nanostructures

    NASA Astrophysics Data System (ADS)

    Tian, Xiaorui; Fang, Yurui; Sun, Mengtao

    2015-12-01

    Chiral fields with large optical chirality are very important in chiral molecules analysis, sensing and other measurements. Plasmonic nanostructures have been proposed to realize such super chiral fields for enhancing weak chiral signals. However, most of them cannot provide uniform chiral near-fields close to the structures, which makes these nanostructures not so efficient for applications. Plasmonic helical nanostructures and blocked squares have been proved to provide uniform chiral near-fields, but structure fabrication is a challenge. In this paper, we show that very simple plasmonic dimer structures can provide uniform chiral fields in the gaps with large enhancement of both near electric fields and chiral fields under linearly polarized light illumination with polarization off the dimer axis at dipole resonance. An analytical dipole model is utilized to explain this behavior theoretically. 30 times of volume averaged chiral field enhancement is gotten in the whole gap. Chiral fields with opposite handedness can be obtained simply by changing the polarization to the other side of the dimer axis. It is especially useful in Raman optical activity measurement and chiral sensing of small quantity of chiral molecule.

  18. Formation of Enhanced Uniform Chiral Fields in Symmetric Dimer Nanostructures

    PubMed Central

    Tian, Xiaorui; Fang, Yurui; Sun, Mengtao

    2015-01-01

    Chiral fields with large optical chirality are very important in chiral molecules analysis, sensing and other measurements. Plasmonic nanostructures have been proposed to realize such super chiral fields for enhancing weak chiral signals. However, most of them cannot provide uniform chiral near-fields close to the structures, which makes these nanostructures not so efficient for applications. Plasmonic helical nanostructures and blocked squares have been proved to provide uniform chiral near-fields, but structure fabrication is a challenge. In this paper, we show that very simple plasmonic dimer structures can provide uniform chiral fields in the gaps with large enhancement of both near electric fields and chiral fields under linearly polarized light illumination with polarization off the dimer axis at dipole resonance. An analytical dipole model is utilized to explain this behavior theoretically. 30 times of volume averaged chiral field enhancement is gotten in the whole gap. Chiral fields with opposite handedness can be obtained simply by changing the polarization to the other side of the dimer axis. It is especially useful in Raman optical activity measurement and chiral sensing of small quantity of chiral molecule. PMID:26621558

  19. Laser enabled Auger decay in argon atoms and dimers

    NASA Astrophysics Data System (ADS)

    Ranitovic, Predrag; Tong, Xiao-Min; Hogle, Craig W.; Toshima, N.; Murnane, M. M.; Kapteyn, H. C.

    2011-05-01

    In rare-gas atoms, Auger decay in which an inner-valence shell ns hole is filled is normally not energetically allowed. However, in the presence of a strong laser field, a new laser-enabled Auger decay channel can open up to increase the double-ionization yield. This process is efficient at high laser intensities, and an ns hole can be filled within a few femtoseconds of its creation. This novel laser-enabled Auger decay (LEAD) process is of fundamental importance for controlling electron dynamics in atoms, molecules, and materials. We then use LEAD to investigate charge transfer in a Coulomb exploding Ar dimer. We can selectively double-ionize either the Ar dimer (threshold ~ 36 eV) or Ar atoms (threshold ~ 43.5 eV) using combined laser (1.5 eV) and XUV photons (36 eV) in a time-resolved fashion, and then comparing the kinetic energy releases. The Ar dimer can be double ionized when the 3s hole is filled by a 3p electron from either one of the two Ar atoms through LEAD. Theoretical calculation will support data taken using COLTRIMS and HHG.

  20. Quantum Monte Carlo calculations of the dimerization energy of borane.

    PubMed

    Fracchia, Francesco; Bressanini, Dario; Morosi, Gabriele

    2011-09-07

    Accurate thermodynamic data are required to improve the performance of chemical hydrides that are potential hydrogen storage materials. Boron compounds are among the most interesting candidates. However, different experimental measurements of the borane dimerization energy resulted in a rather wide range (-34.3 to -39.1) ± 2 kcal/mol. Diffusion Monte Carlo (DMC) simulations usually recover more than 95% of the correlation energy, so energy differences rely less on error cancellation than other methods. DMC energies of BH(3), B(2)H(6), BH(3)CO, CO, and BH(2)(+) allowed us to predict the borane dimerization energy, both via the direct process and indirect processes such as the dissociation of BH(3)CO. Our D(e) = -43.12(8) kcal/mol, corrected for the zero point energy evaluated by considering the anharmonic contributions, results in a borane dimerization energy of -36.59(8) kcal/mol. The process via the dissociation of BH(3)CO gives -34.5(2) kcal/mol. Overall, our values suggest a slightly less D(e) than the most recent W4 estimate D(e) = -44.47 kcal/mol [A. Karton and J. M. L. Martin, J. Phys. Chem. A 111, 5936 (2007)]. Our results show that reliable thermochemical data for boranes can be predicted by fixed node (FN)-DMC calculations.

  1. Formation of Enhanced Uniform Chiral Fields in Symmetric Dimer Nanostructures.

    PubMed

    Tian, Xiaorui; Fang, Yurui; Sun, Mengtao

    2015-12-01

    Chiral fields with large optical chirality are very important in chiral molecules analysis, sensing and other measurements. Plasmonic nanostructures have been proposed to realize such super chiral fields for enhancing weak chiral signals. However, most of them cannot provide uniform chiral near-fields close to the structures, which makes these nanostructures not so efficient for applications. Plasmonic helical nanostructures and blocked squares have been proved to provide uniform chiral near-fields, but structure fabrication is a challenge. In this paper, we show that very simple plasmonic dimer structures can provide uniform chiral fields in the gaps with large enhancement of both near electric fields and chiral fields under linearly polarized light illumination with polarization off the dimer axis at dipole resonance. An analytical dipole model is utilized to explain this behavior theoretically. 30 times of volume averaged chiral field enhancement is gotten in the whole gap. Chiral fields with opposite handedness can be obtained simply by changing the polarization to the other side of the dimer axis. It is especially useful in Raman optical activity measurement and chiral sensing of small quantity of chiral molecule.

  2. On the photophysics and photochemistry of the water dimer

    SciTech Connect

    Segarra-Marti, Javier; Merchan, Manuela; Roca-Sanjuan, Daniel; Lindh, Roland

    2012-12-28

    The photochemistry of the water dimer irradiated by UV light is studied by means of the complete active space perturbation theory//complete active space self-consistent field (CASPT2//CASSCF) method and accurate computational approaches like as minimum energy paths. Both electronic structure computations and ab initio molecular dynamics simulations are carried out. The results obtained show small shifts relative to a single water molecule on the vertical excitation energies of the dimer due to the hydrogen bond placed between the water donor (W{sub D}) and the water acceptor (W{sub A}). A red-shift and a blue-shift are predicted for the W{sub D} and W{sub A}, respectively, supporting previous theoretical and experimental results. The photoinduced chemistry of the water dimer is described as a process occurring between two single water molecules in which the effect of the hydrogen bond plays a minor role. Thus, the photoinduced decay routes correspond to two photodissociation processes, one for each water molecule. The proposed mechanism for the decay channels of the lowest-lying excited states of the system is established as the photochemical production of a hydrogen-bonded H{sub 2}O Horizontal-Ellipsis HO species plus a hydrogen H atom.

  3. Pair entanglement in dimerized spin-s chains

    NASA Astrophysics Data System (ADS)

    Boette, A.; Rossignoli, R.; Canosa, N.; Matera, J. M.

    2016-12-01

    We examine the pair entanglement in the ground state of finite dimerized spin-s chains interacting through anisotropic X Y couplings immersed in a transverse magnetic field by means of a self-consistent pair mean-field approximation. The approach, which makes no a priori assumptions on the pair states, predicts, for sufficiently low coupling between pairs, 2 s distinct dimerized phases for increasing fields below the pair factorizing field, separated by spin-parity-breaking phases. The dimerized phases lead to approximate magnetization and pair entanglement plateaus, while the parity-breaking phases are characterized by weak pair entanglement but non-negligible entanglement of the pair with the rest of the system. These predictions are confirmed by the exact results obtained in finite s =1 and s =3 /2 chains. It is also shown that for increasing values of the spin s , the entanglement of an isolated pair, as measured by the negativity, rapidly saturates in the anisotropic X Y case but increases as s1 /2 in the X X case, reflecting a distinct single-spin entanglement spectrum.

  4. Biologically relevant lyotropic liquid crystalline phases in mixtures of n-octyl β-D-glucoside and water. Determination of the phase diagram by fluorescence spectroscopy.

    PubMed

    Karukstis, Kerry K; Duim, Whitney C; Van Hecke, Gerald R; Hara, Nagiko

    2012-03-29

    When mixed with water, n-octyl β-D-glucoside forms self-assembled nanostructures, several of which are liquid crystalline and all of which depend on the water/glucoside ratio and temperature. For practical use of these phases, a detailed understanding of the conditions under which they exist (i.e., the isobaric phase diagram) is required. We use the fluorescence of the dye molecule prodan as a new approach to probe the phases formed in these mixtures. The prodan fluorescence signal depends on the polarity of its environment and thus the phase(s) in which the dye exists. Visual inspection of the total fluorescence signal can qualitatively determine the phases present, including coexisting phases. Temperature-induced phase changes are also detected from variations observed in the prodan fluorescence spectrum. The sensitivity of this new technique allows the single- and multiple-phase regions to be mapped carefully for the first time.

  5. Isolation, structural elucidation, MS profiling, and evaluation of triglyceride accumulation inhibitory effects of benzophenone C-glucosides from leaves of Mangifera indica L.

    PubMed

    Zhang, Yi; Han, Lifeng; Ge, Dandan; Liu, Xuefeng; Liu, Erwei; Wu, Chunhua; Gao, Xiumei; Wang, Tao

    2013-02-27

    Seventy percent ethanol-water extract from the leaves of Mangifera indica L. (Anacardiaceae) was found to show an inhibitory effect on triglyceride (TG) accumulation in 3T3-L1 cells. From the active fraction, six new benzophenone C-glucosides, foliamangiferosides A(3) (1), A(4) (2), C(4) (3), C(5) (4), C(6) (5), and C(7) (6) together with 11 known benzophenone C-glucosides (7-17) were obtained. In this paper, isolation, structure elucidation (1-6), and MS fragment cleavage pathways of all 17 isolates were studied. 1-6 showed inhibitory effects on TG and free fatty acid accumulation in 3T3-L1 cells at 10 μM.

  6. In vitro and in vivo study of cucurbitacins-type triterpene glucoside from Citrullus colocynthis growing in Saudi Arabia against hepatocellular carcinoma.

    PubMed

    Ayyad, Seif-Eldin N; Abdel-Lateff, Ahmed; Alarif, Walied M; Patacchioli, Francesca R; Badria, Farid A; Ezmirly, Saleh T

    2012-03-01

    Chromatographic investigation of fruits obtained from Citrullus colocynthis, growing in Saudi Arabia, led to isolation of two compounds; Cucurbitacin E glucoside (Cu E, 1), and Cucurbitacin I glucoside (Cu I, 2). The chemical structures of 1 and 2, were elucidated by spectroscopic analyses include; 1D ((1)H and (13)C) and 2D (COSY, HMQC and HMBC) NMR and ESI-MS spectroscopy. The in vitro cytotoxic activity against hepatoma cell line (HepG2) and mice-bearing tumor of Ehrlich's ascites carcinoma (EAC) of the compounds were estimated. Both compounds had potent inhibitory activity on HepG2 with IC(50) 3.5 and 2.8 nmol/mL, respectively. In addition to these activities, the in vivo study employing EAC, showed the capability of both compounds to prolong the survival time, life span and normalize the biochemical parameters of the infected mice with EAC.

  7. Retargeting a maize β-glucosidase to the vacuole--evidence from intact plants that zeatin-O-glucoside is stored in the vacuole.

    PubMed

    Kiran, Nagavalli S; Benková, Eva; Reková, Alena; Dubová, Jaroslava; Malbeck, Jiří; Palme, Klaus; Brzobohatý, Břetislav

    2012-07-01

    Cytokinin (CK) activity is regulated by the complex interplay of their metabolism, transport, stability and cellular/tissue localization. O-glucosides of zeatin-type CKs are postulated to be storage and/or transport forms. Active CK levels are determined in part by their differential distribution of CK metabolites across different subcellular compartments. We have previously shown that overexpressing chloroplast-localized Zm-p60.1, a maize β-glucosidase capable of releasing active cytokinins from their O- and N3-glucosides, perturbs CK homeostasis in transgenic tobacco. We obtained tobacco (Nicotiana tabacum L., cv Petit Havana SR1) plants overexpressing a recombinant Zm-p60.1 that is targeted to the vacuole. The protein is correctly processed and localized to the vacuole. When grown on medium containing exogenous zeatin, transgenic seedlings rapidly accumulate fresh weight due to ectopic growths at the base of the hypocotyl. The presence of the enzyme in these ectopic structures is shown by histochemical staining. CK quantification reveals that these transgenic seedlings are unable to accumulate zeatin-O-glucoside to levels similar to those observed in the wild type. When crossed with tobacco overexpressing the zeatin-O-glucosyltransferase gene from Phaseolus, the vacuolar variant shows an almost complete reversion in the root elongation assay. This is the first evidence from intact plants that the vacuole is the storage organelle for CK O-glucosides and that they are available to attack by Zm-p60.1. We propose the use of Zm-p60.1 as a robust molecular tool that exploits the reversibility of O-glucosylation and enables delicate manipulations of active CK content at the cellular level.

  8. Assessment of extraction parameters on antioxidant capacity, polyphenol content, epigallocatechin gallate (EGCG), epicatechin gallate (ECG) and iriflophenone 3-C-β-glucoside of agarwood (Aquilaria crassna) young leaves.

    PubMed

    Tay, Pei Yin; Tan, Chin Ping; Abas, Faridah; Yim, Hip Seng; Ho, Chun Wai

    2014-08-14

    The effects of ethanol concentration (0%-100%, v/v), solid-to-solvent ratio (1:10-1:60, w/v) and extraction time (30-180 min) on the extraction of polyphenols from agarwood (Aquilaria crassna) were examined. Total phenolic content (TPC), total flavonoid content (TFC) and total flavanol (TF) assays and HPLC-DAD were used for the determination and quantification of polyphenols, flavanol gallates (epigallocatechin gallate--EGCG and epicatechin gallate--ECG) and a benzophenone (iriflophenone 3-C-β-glucoside) from the crude polyphenol extract (CPE) of A. crassna. 2,2'-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity was used to evaluate the antioxidant capacity of the CPE. Experimental results concluded that ethanol concentration and solid-to-solvent ratio had significant effects (p<0.05) on the yields of polyphenol and antioxidant capacity. Extraction time had an insignificant influence on the recovery of EGCG, ECG and iriflophenone 3-C-β-glucoside, as well as radical scavenging capacity from the CPE. The extraction parameters that exhibited maximum yields were 40% (v/v) ethanol, 1:60 (w/v) for 30 min where the TPC, TFC, TF, DPPH, EGCG, ECG and iriflophenone 3-C-β-glucoside levels achieved were 183.5 mg GAE/g DW, 249.0 mg QE/g DW, 4.9 mg CE/g DW, 93.7%, 29.1 mg EGCG/g DW, 44.3 mg ECG/g DW and 39.9 mg iriflophenone 3-C-β-glucoside/g DW respectively. The IC50 of the CPE was 24.6 mg/L.

  9. A flavonoid 3-O-glucoside:2″-O-glucosyltransferase responsible for terminal modification of pollen-specific flavonols in Arabidopsis thaliana

    PubMed Central

    Yonekura-Sakakibara, Keiko; Nakabayashi, Ryo; Sugawara, Satoko; Tohge, Takayuki; Ito, Takuya; Koyanagi, Misuzu; Kitajima, Mariko; Takayama, Hiromitsu; Saito, Kazuki

    2014-01-01

    Flavonol 3-O-diglucosides with a 1→2 inter-glycosidic linkage are representative pollen-specific flavonols that are widely distributed in plants, but their biosynthetic genes and physiological roles are not well understood. Flavonoid analysis of four Arabidopsis floral organs (pistils, stamens, petals and calyxes) and flowers of wild-type and male sterility 1 (ms1) mutants, which are defective in normal development of pollen and tapetum, showed that kaempferol/quercetin 3-O-β-d-glucopyranosyl-(1→2)-β-d-glucopyranosides accumulated in Arabidopsis pollen. Microarray data using wild-type and ms1 mutants, gene expression patterns in various organs, and phylogenetic analysis of UDP-glycosyltransferases (UGTs) suggest that UGT79B6 (At5g54010) is a key modification enzyme for determining pollen-specific flavonol structure. Kaempferol and quercetin 3-O-glucosyl-(1→2)-glucosides were absent from two independent ugt79b6 knockout mutants. Transgenic ugt79b6 mutant lines transformed with the genomic UGT79B6 gene had the same flavonoid profile as wild-type plants. Recombinant UGT79B6 protein converted kaempferol 3-O-glucoside to kaempferol 3-O-glucosyl-(1→2)-glucoside. UGT79B6 recognized 3-O-glucosylated/galactosylated anthocyanins/flavonols but not 3,5- or 3,7-diglycosylated flavonoids, and prefers UDP-glucose, indicating that UGT79B6 encodes flavonoid 3-O-glucoside:2″-O-glucosyltransferase. A UGT79B6-GUS fusion showed that UGT79B6 was localized in tapetum cells and microspores of developing anthers. PMID:24916675

  10. Resistance of glucose-6-phosphate dehydrogenase deficiency to malaria: effects of fava bean hydroxypyrimidine glucosides on Plasmodium falciparum growth in culture and on the phagocytosis of infected cells.

    PubMed

    Ginsburg, H; Atamna, H; Shalmiev, G; Kanaani, J; Krugliak, M

    1996-07-01

    The balanced polymorphism of glucose-6-phosphate dehydrogenase deficiency (G6PD-) is believed to have evolved through the selective pressure of malarial combined with consumption of fava beans. The implicated fava bean constituents are the hydroxypyrimidine glucosides vicine and convicine, which upon hydrolysis of their beta-O-glucosidic bond, became protein pro-oxidants. In this work we show that the glucosides inhibit the growth of Plasmodium falciparum, increase the hexose-monophosphate shunt activity and the phagocytosis of malaria-infected erythrocytes. These activities are exacerbated in the presence of beta-glucosidase, implicating their pro-oxidant aglycones in the toxic effect, and are more pronounced in infected G6PD- erythrocytes. These results suggest that G6PD- infected erythrocytes are more susceptible to phagocytic cells, and that fava bean pro-oxidants are more efficiently suppressing parasite propagation in G6PD- erythrocytes, either by directly affecting parasite growth, or by means of enhanced phagocytic elimination of infected cells. The present findings could account for the relative resistance of G6PD- bearers to falciparum malaria, and establish a link between dietary habits and malaria in the selection of the G6PD- genotype.

  11. Synthesis and photophysical properties of a single bond linked tetracene dimer

    NASA Astrophysics Data System (ADS)

    Sun, Tingting; Shen, Li; Liu, Heyuan; Sun, Xuan; Li, Xiyou

    2016-07-01

    A tetracene dimer linked directly by a single bond has been successfully prepared by using electron withdrawing groups to improve the stability. The molecular structure of this dimer is characterized by 1H NMR, MALDI-TOF mass spectroscopy, and elemental analysis. The minimized molecular structure and X-ray crystallography reveal that the tetracene subunits of this dimer adopt an orthogonal configuration. Its absorption spectrum differs significantly from that of its monomeric counterpart, suggesting the presence of strong interactions between the two tetracene subunits. The excited state of this dimer is delocalized on both two tetracene subunits, which is significantly different from that of orthogonal anthracene dimers, but similar with that observed for orthogonal pentacene dimer. Most of the excited states of this dimer decay by radioactive channels, which is different from the localized twisted charge transfer state (LTCT) channel of anthracene dimers and the singlet fission (SF) channel of pentacene dimers. The results of this research suggest that similar orthogonal configurations caused different propertied for acene dimers with different conjugation length.

  12. HIV-1 RNA genome dimerizes on the plasma membrane in the presence of Gag protein.

    PubMed

    Chen, Jianbo; Rahman, Sheikh Abdul; Nikolaitchik, Olga A; Grunwald, David; Sardo, Luca; Burdick, Ryan C; Plisov, Sergey; Liang, Edward; Tai, Sheldon; Pathak, Vinay K; Hu, Wei-Shau

    2016-01-12

    Retroviruses package a dimeric genome comprising two copies of the viral RNA. Each RNA contains all of the genetic information for viral replication. Packaging a dimeric genome allows the recovery of genetic information from damaged RNA genomes during DNA synthesis and promotes frequent recombination to increase diversity in the viral population. Therefore, the strategy of packaging dimeric RNA affects viral replication and viral evolution. Although its biological importance is appreciated, very little is known about the genome dimerization process. HIV-1 RNA genomes dimerize before packaging into virions, and RNA interacts with the viral structural protein Gag in the cytoplasm. Thus, it is often hypothesized that RNAs dimerize in the cytoplasm and the RNA-Gag complex is transported to the plasma membrane for virus assembly. In this report, we tagged HIV-1 RNAs with fluorescent proteins, via interactions of RNA-binding proteins and motifs in the RNA genomes, and studied their behavior at the plasma membrane by using total internal reflection fluorescence microscopy. We showed that HIV-1 RNAs dimerize not in the cytoplasm but on the plasma membrane. Dynamic interactions occur among HIV-1 RNAs, and stabilization of the RNA dimer requires Gag protein. Dimerization often occurs at an early stage of the virus assembly process. Furthermore, the dimerization process is probably mediated by the interactions of two RNA-Gag complexes, rather than two RNAs. These findings advance the current understanding of HIV-1 assembly and reveal important insights into viral replication mechanisms.

  13. Direct Detection of α-Synuclein Dimerization Dynamics: Single-Molecule Fluorescence Analysis

    PubMed Central

    Lv, Zhengjian; Krasnoslobodtsev, Alexey V.; Zhang, Yuliang; Ysselstein, Daniel; Rochet, Jean-Christophe; Blanchard, Scott C.; Lyubchenko, Yuri L.

    2015-01-01

    The aggregation of α-synuclein (α-Syn) is linked to Parkinson’s disease. The mechanism of early aggregation steps and the effect of pathogenic single-point mutations remain elusive. We report here a single-molecule fluorescence study of α-Syn dimerization and the effect of mutations. Specific interactions between tethered fluorophore-free α-Syn monomers on a substrate and fluorophore-labeled monomers diffusing freely in solution were observed using total internal reflection fluorescence microscopy. The results showed that wild-type (WT) α-Syn dimers adopt two types of dimers. The lifetimes of type 1 and type 2 dimers were determined to be 197 ± 3 ms and 3334 ± 145 ms, respectively. All three of the mutations used, A30P, E46K, and A53T, increased the lifetime of type 1 dimer and enhanced the relative population of type 2 dimer, with type 1 dimer constituting the major fraction. The kinetic stability of type 1 dimers (expressed in terms of lifetime) followed the order A30P (693 ± 14 ms) > E46K (292 ± 5 ms) > A53T (226 ± 6 ms) > WT (197 ± 3 ms). Type 2 dimers, which are more stable, had lifetimes in the range of several seconds. The strongest effect, observed for the A30P mutant, resulted in a lifetime 3.5 times higher than observed for the WT type 1 dimer. This mutation also doubled the relative fraction of type 2 dimer. These data show that single-point mutations promote dimerization, and they suggest that the structural heterogeneity of α-Syn dimers could lead to different aggregation pathways. PMID:25902443

  14. Stilbene glucoside from Polygonum multiflorum Thunb.: a novel natural inhibitor of advanced glycation end product formation by trapping of methylglyoxal.

    PubMed

    Lv, Lishuang; Shao, Xi; Wang, Liyan; Huang, Derong; Ho, Chi-Tang; Sang, Shengmin

    2010-02-24

    Methylglyoxal (MGO), the reactive dicarbonyl intermediate generated during the nonenzymatic glycation between reducing sugars and amino groups of proteins, lipids, and DNA, is the precursor of advanced glycation end products (AGEs). Many studies have shown that AGEs play a major pathogenic role in diabetes and its complications. This study found that 2,3,5,4'-tetrahydroxystilbene 2-O-beta-D-glucoside (THSG), the major bioactive compound from Polygonum multiflorum Thunb., can efficiently inhibit the formation of AGEs in a dose-dependent manner by trapping reactive MGO under physiological conditions (pH 7.4, 37 degrees C). More than 60% MGO was trapped by THSG within 24 h, which was much more effective than resveratrol and its methylated derivative, pterostilbene, the two major bioactive dietary stilbenes. The major mono- and di-MGO adducts of THSG were successfully purified and found to be mixtures of tautomers. LC-MS and NMR data showed that positions 4 and 6 of the A ring were the major active sites for trapping MGO. It was also found that THSG could significantly inhibit the formation of AGEs in the human serum albumin (HSA)-MGO assay and both mono- and di-MGO adducts of THSG were detected in this assay using LC-MS. The results suggest that the ability of THSG to trap reactive dicarbonyl species makes it a potential natural inhibitor of AGEs.

  15. Behaviour of cyanidin-3-glucoside, β-lactoglobulin and polysaccharides nanoparticles in bulk and oil-in-water interfaces.

    PubMed

    Oliveira, Ana; Ruiz-Henestrosa, Víctor M Pizones; von Staszewski, Mariana; Pilosof, Ana M R; Pintado, Manuela

    2015-11-05

    Particle size distributions as well the interfacial and rheological properties of the films at the oil/water interface were used to study the effect of the interacting system between β-lactoglobulin, cyanidin-3-glucoside and pectin or chitosan in buffer solutions. The particles obtained were smaller with cy-3-gluc-β-lg-pectin and had reduced polydispersity with cy-3-gluc-β-lg-chitosan. Based on time dependent surface pressure results, β-lg-pectin mixtures showed a slower increase at the beginning of the measurement, while β-lg-chitosan mixtures showed no differences with β-lg alone. Contrarily, dilatational properties increased for ternary chitosan mixtures, but they remained similar to the pure protein in ternary pectin mixtures. Cy-3-gluc interfacial properties were reduced by the presence of pectin and chitosan. The interactions between cy-3-gluc and the biopolymers that have been selected in the present work resulted in a lower content of free polyphenol, reduced antioxidant properties as well as free β-lg. The impact of this effect was more relevant when pectin was used.

  16. Spectrophotometric study of the copigmentation of malvidin 3-O-glucoside with p-coumaric, vanillic and syringic acids.

    PubMed

    Malaj, Naim; De Simone, Bruna Clara; Quartarolo, Angelo Domenico; Russo, Nino

    2013-12-15

    Anthocyanins are a natural source of pigments in plants and their processed food products have become attractive and excellent candidates to replace the synthetic colourants due to their characteristic intense colours and associated health benefits. The intermolecular copigmentation between anthocyanins and other colourless compounds has been reported to be an important way to enhance and stabilise the colour intensity of aqueous solutions. In the present work we report the equilibrium constant, stoichiometric ratio and the thermodynamic parameters (ΔG°, ΔH° and ΔS°) related to the intermolecular copigmentation reactions of the anthocyanin malvidin 3-O-glucoside with one hydroxycinnamic acid (p-coumaric acid) and two O-methylated hydroxybenzoic acids (vanillic and syringic acid). Different factors which affect their interactions such as copigment concentration, pH and temperature of the medium are examined at two pH levels (pH=2.50 and 3.65) corresponding to those of the major food mediums where these reactions take place (fruit juices, wine, jams etc.).

  17. Fate of deoxynivalenol and deoxynivalenol-3-glucoside during cereal-based thermal food processing: a review study.

    PubMed

    Wu, Qinghua; Kuča, Kamil; Humpf, Hans-Ulrich; Klímová, Blanka; Cramer, Benedikt

    2017-02-01

    Deoxynivalenol (DON), the most commonly occurring trichothecene in nature, may affect animal and human health through causing diarrhea, vomiting, gastrointestinal inflammation, and immunomodulation. DON-3-glucoside (DON-3G) as a major plant metabolite of the mycotoxin is another "emerging" food safety issue in recent years. Humans may experience potential health risks by consuming DON-contaminated food products. Thus, it is crucial for human and animal health to study also the degradation of DON and DON-3G during thermal food processing. Baking, boiling, steaming, frying, and extrusion cooking are commonly used during thermal food processing and have promising effects on the reduction of mycotoxins in food. For DON, however, the observed effects of these methods, as reported in numerous studies, are ambiguous and do not present a clear picture with regard to reduction or transformation. This review summarized the influence of thermal processing on the stability of DON and the formation of degradation/conversion products. Besides this, also a release of DON and DON-3G from food matrix as well as the release of DON from DON-3G during processing is discussed. In addition, some conflicting findings as reported from the studies on thermal processing as well as cause-effect relationships of the different thermal procedures are explored. Finally, the potential toxic profiles of DON degradation products are discussed as well when data are available.

  18. Analysis of deoxynivalenol and deoxynivalenol-3-glucosides content in Canadian spring wheat cultivars inoculated with Fusarium graminearum.

    PubMed

    Amarasinghe, Chami C; Simsek, Senay; Brûlé-Babel, Anita; Fernando, W G Dilantha

    2016-07-01

    Contamination of wheat grains with Fusarium mycotoxins and their modified forms is an important issue in wheat industry. The objective of this study was to analyse the deoxynivalenol (DON) and deoxynivalenol-3-glucosides (D3G) content in Canadian spring wheat cultivars grown in two locations, inoculated with a mixture of 3-acetyldeoxynivalenol (3-ADON)-producing Fusarium graminearum strains and a mixture of 15-acetlyldeoxynivalenol (15-ADON)-producing F. graminearum strains. According to the analysis of variance, significant differences were observed among the cultivars for Fusarium head blight (FHB) disease index, Fusarium-damaged kernel percentage (%FDK), DON content and D3G content. When the effect of chemotype was considered, significant differences were observed for FHB disease index, FDK percentage and DON content. The D3G content and D3G/DON ratio were not significantly different between the chemotypes, except for D3G content at the Winnipeg location. The Pearson correlation coefficient between DON and D3G was 0.84 and 0.77 at Winnipeg and Carman respectively. The highest D3G/DON ratio was observed in cultivars Carberry (44%) in Carman and CDC Kernen (63.8%) in Winnipeg. The susceptible cultivars showed lower D3G/DON ratio compared with the cultivars rated as moderately resistant and intermediate. The current study indicated that Canadian spring cultivars produce D3G upon Fusarium infection.

  19. Deoxynivalenol & Deoxynivalenol-3-Glucoside Mitigation through Bakery Production Strategies: Effective Experimental Design within Industrial Rusk-Making Technology.

    PubMed

    Generotti, Silvia; Cirlini, Martina; Malachova, Alexandra; Sulyok, Michael; Berthiller, Franz; Dall'Asta, Chiara; Suman, Michele

    2015-07-24

    In the scientific field, there is a progressive awareness about the potential implications of food processing on mycotoxins especially concerning thermal treatments. High temperatures may cause, in fact, transformation or degradation of these compounds. This work is aimed to study the fate of mycotoxins during bakery processing, focusing on deoxynivalenol (DON) and deoxynivalenol-3-glucoside (DON3Glc), along the chain of industrial rusk production. Starting from naturally contaminated bran, we studied how concentrations of DON and DON3Glc are influenced by modifying ingredients and operative conditions. The experiments were performed using statistical Design of Experiment (DoE) schemes to synergistically explore the relationship between mycotoxin reduction and the indicated processing transformation parameters. All samples collected during pilot plant experiments were analyzed with an LC-MS/MS multimycotoxin method. The obtained model shows a good fitting, giving back relevant information in terms of optimization of the industrial production process, in particular suggesting that time and temperature in baking and toasting steps are highly relevant for minimizing mycotoxin level in rusks. A reduction up to 30% for DON and DON3Glc content in the finished product was observed within an acceptable technological range.

  20. Binding of the alkaloid aristololactam-β-D-glucoside and daunomycin to human hemoglobin: spectroscopy and calorimetry studies.

    PubMed

    Das, Abhi; Suresh Kumar, Gopinatha

    2016-01-01

    The interaction of the plant alkaloid aristololactam-β-D-glucoside (ADG) and the anticancer agent daunomycin (DAN) with human hemoglobin was studied by different spectroscopic and calorimetric methods. The binding affinity values of ADG and DAN, estimated from spectroscopic experiments, were 3.79 × 10(4) and 6.68 × 10(4) M(-1), respectively. From circular dichroism, 3D fluorescence, and FTIR studies it was observed that, DAN induced stronger conformational changes than ADG in the protein. From synchronous fluorescence spectroscopy results, a pronounced shift in the maximum emission wavelength of tyrosine residues was observed in both cases suggesting that the drugs changed the polarity around tyrosine residues with marginal change around the tryptophan residues. The thermodynamics of the binding interaction analyzed using microcalorimetry presented single binding events that were exothermic in nature in both cases. The binding was driven by large positive standard molar entropy changes with small favorable enthalpy contributions. Negative heat capacity changes in both cases are correlated to the involvement of significant hydrophobic forces in the complexation process. The affinity of DAN to Hb was higher than that of ADG.

  1. Anti-diabetic effects of luteolin and luteolin-7-O-glucoside on KK-A(y) mice.

    PubMed

    Zang, Yanqing; Igarashi, Kiharu; Li, Yu

    2016-08-01

    Anti-diabetic potential of luteolin (LU) and luteolin-7-O-glucoside (LUG) were investigated in the amount of equimolar on KK-A(y) mice. The results showed that both of LU and LUG significantly improved blood glucose, HbA1c, insulin, and HOMR-IR levels. Anti-inflammatory and anti-oxidative effects of the LU and LUG were also proved. Furthermore, TGs in serum and liver were significantly decreased in the LU and LUG groups, as well as the mRNA expression of fat acid expression-related genes (SREBP-1c), compared to the basal diet group (CON). When compared the effects between the LU and LUG groups, TGs of the LU group were lower than those of the LUG group, accompanied with significantly decreased FAS activity and SREBP-1c expression in liver. These results suggested that both LU and LUG had positive effects of anti-diabetes on KK-A(y) mice, but LU more potently ameliorated diabetes than LUG, which might be attributed to the inhibitory of lipid synthesis.

  2. Tetrahydroxystilbene glucoside attenuates MPP+-induced apoptosis in PC12 cells by inhibiting ROS generation and modulating JNK activation.

    PubMed

    Li, Xiaobing; Li, Yan; Chen, Jianzong; Sun, Jing; Li, Xiaofeng; Sun, Xin; Kang, Xiaogang

    2010-10-08

    It is known that oxidative stress plays a major role in the progression of Parkinson's disease (PD). Previous studies have suggested that 2,3,5,4'-tetrahydroxystilbene-2-O-beta-D-glucoside (TSG), an active component extracted from a traditional Chinese herb Polygonum multiflorum Thunb., has significant antioxidant and free radical-scavenging activities. This is the first study that investigated the protective effects of TSG against MPP(+)-induced apoptosis in PC12 cells and determined the underlying mechanism. The results showed that incubation of PC12 cells with TSG before exposing them to MPP(+) could significantly decrease cell viability loss and reverse cell apoptosis in a dose-dependent manner. The anti-apoptotic effects of TSG were probably mediated via the inhibition of ROS generation and modulation of JNK activation because TSG blocked ROS increase and JNK phosphorylation induced by MPP(+). Taken together, these results indicated that TSG may provide a useful therapeutic strategy for the treatment of neurodegenerative diseases such as PD.

  3. Facile preparation of water soluble curcuminoids extracted from turmeric (Curcuma longa L.) powder by using steviol glucosides.

    PubMed

    Nguyen, Thi Thanh Hanh; Si, Jinbeom; Kang, Choongil; Chung, Byoungsang; Chung, Donghwa; Kim, Doman

    2017-01-01

    Curcuminoids from rhizomes of Curcuma longa possess various biological activities. However, low aqueous solubility and consequent poor bioavailability of curcuminoids are major limitations to their use. In this study, curcuminoids extracted from turmeric powder using stevioside (Ste), rebaudioside A (RebA), or steviol glucosides (SG) were solubilized in water. The optimum extraction condition by Ste, RebA, or SG resulted in 11.3, 9.7, or 6.7mg/ml water soluble curcuminoids. Curcuminoids solubilized in water showed 80% stability at pH from 6.0 to 10.0 after 1week of storage at 25°C. The particle sizes of curcuminoids prepared with Ste, RebA, and SG were 110.8, 95.7, and 32.7nm, respectively. The water soluble turmeric extracts prepared with Ste, RebA, and SG showed the 2,2-diphenyl-1-picrylhydrazyl radical scavenging (SC50) activities of 127.6, 105.4, and 109.8μg/ml, and the inhibition activities (IC50) against NS2B-NS3(pro) from dengue virus type IV of 14.1, 24.0 and 15.3μg/ml, respectively.

  4. Tetrahydroxystilbene glucoside inhibits TNF-α-induced migration of vascular smooth muscle cells via suppression of vimentin.

    PubMed

    Yao, Wenjuan; Sun, Qinju; Huang, Lei; Meng, Guoliang; Wang, Huiming; Jing, Xiang; Zhang, Wei

    2015-07-28

    Vascular smooth muscle cell (VSMC) migration triggered by TNF-α is an important event that occurs during the development of atherosclerosis. 2,3,5,4'-Tetrahydroxystilbene-2-O-β-d-glucoside (TSG) has been proven to exhibit significant anti-atherosclerotic activity. Herein we investigate the inhibitory effect of TSG on TNF-α-induced VSMC migration and explore the underlying mechanisms. TSG pretreatment markedly inhibited TNF-α-induced cell migration. The inhibition of vimentin redistribution and expression was involved in the inhibitory effect of TSG on VSMC migration. The suppression of vimentin expression by shRNA in VSMCs significantly inhibited TNF-α-induced cell migration. Furthermore, TSG inhibited the TNF-α-induced expression of TGFβ1 and TGFβR1, and phosphorylation of TGFβR1 and Smad2/3. TSG also suppressed the nuclear translocation of Smad4 induced by TNF-α. These results suggest that TSG inhibits VSMC migration induced by TNF-α through inhibiting vimentin rearrangement and expression. The interruption of TGFβ/Smad pathway appears to be responsible for the suppression of TSG on vimentin expression.

  5. ABCC1, an ATP Binding Cassette Protein from Grape Berry, Transports Anthocyanidin 3-O-Glucosides[W][OA

    PubMed Central

    Francisco, Rita Maria; Regalado, Ana; Ageorges, Agnès; Burla, Bo J.; Bassin, Barbara; Eisenach, Cornelia; Zarrouk, Olfa; Vialet, Sandrine; Marlin, Thérèse; Chaves, Maria Manuela; Martinoia, Enrico; Nagy, Réka

    2013-01-01

    Accumulation of anthocyanins in the exocarp of red grapevine (Vitis vinifera) cultivars is one of several events that characterize the onset of grape berry ripening (véraison). Despite our thorough understanding of anthocyanin biosynthesis and regulation, little is known about the molecular aspects of their transport. The participation of ATP binding cassette (ABC) proteins in vacuolar anthocyanin transport has long been a matter of debate. Here, we present biochemical evidence that an ABC protein, ABCC1, localizes to the tonoplast and is involved in the transport of glucosylated anthocyanidins. ABCC1 is expressed in the exocarp throughout berry development and ripening, with a significant increase at véraison (i.e., the onset of ripening). Transport experiments using microsomes isolated from ABCC1-expressing yeast cells showed that ABCC1 transports malvidin 3-O-glucoside. The transport strictly depends on the presence of GSH, which is cotransported with the anthocyanins and is sensitive to inhibitors of ABC proteins. By exposing anthocyanin-producing grapevine root cultures to buthionine sulphoximine, which reduced GSH levels, a decrease in anthocyanin concentration is observed. In conclusion, we provide evidence that ABCC1 acts as an anthocyanin transporter that depends on GSH without the formation of an anthocyanin-GSH conjugate. PMID:23723325

  6. Isolation of a flavonoid, apigenin 7-O-glucoside, from Mentha longifolia (L.) Hudson subspecies longifolia and its genotoxic potency.

    PubMed

    Gulluce, Medine; Orhan, Furkan; Yanmis, Derya; Arasoglu, Tulin; Guvenalp, Zuhal; Demirezer, Lutfiye Omur

    2015-09-01

    Mentha is a medicinal and aromatic plant belonging to the Lamiaceae family, which is widely used in food, flavor, cosmetic and pharmaceutical industries. Recently, it has been found that the use of Mentha as a pharmaceutical source is based on its phytochemical constituents that have far been identified as tannins, saponins, phenolic acids and flavonoids. This study was designed to evaluate the mutagenic and antimutagenic activities of apigenin 7-O-glucoside (A7G), a flavonoid isolated from Mentha longifolia (L.) Hudson subspecies longifolia (ML). The possible antimutagenic potential of A7G was examined against mutagens ethyl methanesulfonate and acridine in an eukaryotic cell system Saccharomyces cerevisiae and sodium azide in Salmonella typhimurium TA1535 and 9-aminoacridine in S. typhimurium TA1537. According to our findings, any concentrations of the A7G used did not show mutagenic activity but exerted strong antimutagenic activities at tested concentrations. The inhibition rates for the Ames test ranged from 27.2% (S. typhimurium TA1535: 0.4 μM/plate) to 91.1% (S. typhimurium TA1537: 0.2 μM/plate) and for the yeast deletion assay from 4% to 57.7%. This genotoxicological study suggests that a flavonoid from ML owing to antimutagenic properties is of great pharmacological importance and might be beneficial to industries producing food additives, cosmetics and pharmaceuticals products.

  7. In-vivo absorption of pinocembrin-7-O-β-D-glucoside in rats and its in-vitro biotransformation

    PubMed Central

    Guo, Wei-Wei; Qiu, Feng; Chen, Xiao-Qing; Ba, Yin-Ying; Wang, Xing; Wu, Xia

    2016-01-01

    Pinocembrin-7-O-β-D-glucoside (PCBG), a flavonoid isolated from Penthorum chinense Pursh., has significant liver-protecting effects. The pharmacokinetics of PCBG and its major metabolite pinocembrin (PCB) in rats were investigated in this study. A sensitive and accurate UPLC-MS/MS method was developed and validated for the simultaneous quantitative determination of PCBG and PCB in rat plasma after oral and intravenous administration of PCBG. After intravenous administration, PCBG was the main form in plasma. In contrast, after oral administration, the concentration of PCB was about 4-fold higher than that of PCBG, indicating that PCBG was metabolized to PCB. We also investigated the biotransformation of PCBG in vitro in order to understand whether the pH and the intestinal flora of gastrointestinal tract could affect the metabolism of PCBG. PCBG was incubated in rat plasma, liver homogenization, gastrointestial contents, liver microsomes (RLM) and hepatocytes in vitro. The data showed that PCB was quickly formed in the gastrointestinal incubation but PCBG was converted to PCB gradually in other incubations. The results indicated that the majority of PCBG was converted to its aglycone PCB in digestive system after oral administration, and PCB could be the active ingredient in the body. PMID:27378517

  8. Characterization of intermolecular interaction between cyanidin-3-glucoside and bovine serum albumin: spectroscopic and molecular docking methods.

    PubMed

    Shi, Jie-hua; Wang, Jing; Zhu, Ying-yao; Chen, Jun

    2014-08-01

    The intermolecular interaction between cyanidin-3-glucoside (Cy-3-G) and bovine serum albumin (BSA) was investigated using fluorescence, circular dichroism and molecular docking methods. The experimental results revealed that the fluorescence quenching of BSA at 338 nm by Cy-3-G resulted from the formation of Cy-3-G-BSA complex. The number of binding sites (n) for Cy-3-G binding on BSA was approximately equal to 1. The experimental and molecular docking results revealed that after binding Cy-3-G to BSA, Cy-3-G is closer to the Tyr residue than the Trp residue, the secondary structure of BSA almost not change, the binding process of Cy-3-G with BSA is spontaneous, and Cy-3-G can be inserted into the hydrophobic cavity of BSA (site II') in the binding process of Cy-3-G with BSA. Moreover, based on the sign and magnitude of the enthalpy and entropy changes (ΔH(0)  = - 29.64 kcal/mol and ΔS(0)  = - 69.51 cal/mol K) and the molecular docking results, it can be suggested that the main interaction forces of Cy-3-G with BSA are Van der Waals and hydrogen bonding interactions.

  9. Semiquinone glucoside derivative (SQGD) isolated from Bacillus sp. INM-1 protects against gamma radiation-induced oxidative stress.

    PubMed

    Mishra, Saurabh; Malhotra, Poonam; Gupta, Ashutosh K; Singh, Praveen K; Javed, Saleem; Kumar, Raj

    2014-03-01

    In the present study, radioprotective potential of Semiquinone glucoside derivative (SQGD) isolated from radioresistant bacterium Bacillus sp. INM-1 was evaluated. γ-Radiation induced protein carbonylation, plasmid DNA damage, enzyme functional impairment, lipid peroxidation, HO radicals generation and their protection by SQGD was assessed. As a result of SQGD treatment, significant inhibition (p<0.05) in protein carbonylation was observed with BSA. SQGD treatment was found to restore supercoiled (~70±3.21%) form of irradiated plasmid DNA against γ-irradiation. SQGD protects enzymes (EcoR1 and BamH1) against radiation-induced dysfunctioning. SQGD significantly inhibited (p<0.05) lipid peroxidation in liposomes, brain and liver homogenate. Higher HO(•) radicals-averting activity of SQGD was observed in the serum and liver homogenate of C57BL/6 mice against H2O2-induced oxidative stress. In conclusion, SQGD demonstrates excellent radical-scavenging activity towards bio-macromolecules in irradiated environment and can be developed as an ideal radioprotector against radiation-induced oxidative stress in future.

  10. Flavonol Glucoside and Antioxidant Enzyme Biosynthesis Affected by Mycorrhizal Fungi in Various Cultivars of Onion (Allium cepa L.).

    PubMed

    Mollavali, Mohanna; Bolandnazar, Saheb Ali; Schwarz, Dietmar; Rohn, Sascha; Riehle, Peer; Zaare Nahandi, Fariborz

    2016-01-13

    The objective of this study was to investigate the impact of mycorrhizal symbiosis on qualitative characteristics of onion (Allium cepa L.). For this reason, five onion cultivars with different scale color and three different strains of arbuscular mycorrhizal fungi (Diversispora versiformis, Rhizophagus intraradices, Funneliformis mosseae) were used. Red cultivars, mainly 'Red Azar-shahr', showed the highest content in vitamin C, flavonols, and antioxidant enzymes. Mycorrhizal inoculation increased total phenolic, pyruvic acid, and vitamin C of onion plants. Considerable increase was observed in quercetin-4'-O-monoglucoside and isorhamnetin-4'-O-monoglucoside content in plants inoculated with Diversispora versiformis, but quercetin-3,4'-O-diglucoside was not significantly influenced. Analyses for phenylalanine ammonia-lyase (PAL) and antioxiodant enzyme activities such as polyphenol oxidase (PPO), catalase (CAT), and peroxidase (POD) revealed that all except PPO were enhanced by mycorrhizal inoculation. Overall, these findings suggested that mycorrhizal inoculation influenced biosynthesis of flavonol glucosides and antioxidant enzymes by increasing nutrient uptake or by induction of the plant defense system.

  11. Deoxynivalenol & Deoxynivalenol-3-Glucoside Mitigation through Bakery Production Strategies: Effective Experimental Design within Industrial Rusk-Making Technology

    PubMed Central

    Generotti, Silvia; Cirlini, Martina; Malachova, Alexandra; Sulyok, Michael; Berthiller, Franz; Dall’Asta, Chiara; Suman, Michele

    2015-01-01

    In the scientific field, there is a progressive awareness about the potential implications of food processing on mycotoxins especially concerning thermal treatments. High temperatures may cause, in fact, transformation or degradation of these compounds. This work is aimed to study the fate of mycotoxins during bakery processing, focusing on deoxynivalenol (DON) and deoxynivalenol-3-glucoside (DON3Glc), along the chain of industrial rusk production. Starting from naturally contaminated bran, we studied how concentrations of DON and DON3Glc are influenced by modifying ingredients and operative conditions. The experiments were performed using statistical Design of Experiment (DoE) schemes to synergistically explore the relationship between mycotoxin reduction and the indicated processing transformation parameters. All samples collected during pilot plant experiments were analyzed with an LC-MS/MS multimycotoxin method. The obtained model shows a good fitting, giving back relevant information in terms of optimization of the industrial production process, in particular suggesting that time and temperature in baking and toasting steps are highly relevant for minimizing mycotoxin level in rusks. A reduction up to 30% for DON and DON3Glc content in the finished product was observed within an acceptable technological range. PMID:26213969

  12. Long Chain Fatty Acid Acylated Derivatives of Quercetin-3-O-Glucoside as Antioxidants to Prevent Lipid Oxidation

    PubMed Central

    Warnakulasuriya, Sumudu N.; Ziaullah; Rupasinghe, H.P. Vasantha

    2014-01-01

    Flavonoids have shown promise as natural plant-based antioxidants for protecting lipids from oxidation. It was hypothesized that their applications in lipophilic food systems can be further enhanced by esterification of flavonoids with fatty acids. Quercetin-3-O-glucoside (Q3G) was esterified individually with six selected long chain fatty acids: stearic acid (STA), oleic acid (OLA), linoleic acid (LNA), α-linolenic acid (ALA), eicosapentaenoic acid (EPA) and decosahexaenoic acid (DHA), using Candida antarctica B lipase as the biocatalyst. The antioxidant activity of esterified flavonoids was evaluated using lipid oxidation model systems of poly-unsaturated fatty acids-rich fish oil and human low density lipoprotein (LDL), in vitro. In the oil-in-water emulsion, Q3G esters exhibited 50% to 100% inhibition in primary oxidation and 30% to 75% inhibition in secondary oxidation. In bulk oil, Q3G esters did not provide considerable protection from lipid oxidation; however, Q3G demonstrated more than 50% inhibition in primary oxidation. EPA, DHA and ALA esters of Q3G showed significantly higher inhibition in Cu2+- and peroxyl radical-induced LDL oxidation in comparison to Q3G. PMID:25384198

  13. Isolation and identification of trans-2- and trans-3-hydroxy-1,8-cineole glucosides from Alpinia galanga.

    PubMed

    Someya, Y; Kobayashi, A; Kubota, K

    2001-04-01

    Three hydroxy-1,8-cineole glucopyranosides, (1R, 2R, 4S)- and (1S, 2S, 4R)-trans-2-hydroxy-1,8-cineole beta-D-glucopyranosides, and (1R, 3S, 4S)-trans-3-hydroxy-1,8-cineole beta-D-glucopyranoside, which are possible precursors of acetoxy-1,8-cineoles as unique aroma components, were isolated from the rhizomes of greater galangal (Alpinia galanga W.). Their structures were analyzed by FAB-MS and NMR spectrometry, and the absolute configulation of each aglycone was determined by using a GC-MS analysis with a capillary column coated with a chiral stationary phase. The composition of the diastereomers of (1R, 2R, 4S)- and (1S, 2S, 4R)-trans-2-hydroxy-1,8-cineole beta-D-glucopyranosides in the rhizomes was determined as 3:7 by a GC-MS analysis after preparing the trifluoroacetate derivatives of the glucosides.

  14. Effects of baking on cyanidin-3-glucoside content and antioxidant properties of black and yellow soybean crackers.

    PubMed

    Slavin, Margaret; Lu, Yingjian; Kaplan, Nicholas; Yu, Liangli Lucy

    2013-11-15

    Black soybean is a potential functional food ingredient with high anthocyanin content, but the ability to maintain anthocyanin content under dry heat processing has not been reported. This study investigated the effects of soybean seed coat colour and baking time-temperature combinations on the extractable antioxidant properties of a soy cracker food model. Crackers prepared with black soybeans had significantly higher TPC, total isoflavones, and peroxyl, hydroxyl, and ABTS(+) radical scavenging abilities than their yellow counterparts, at all time-temperature combinations. Cyanidin-3-glucoside (C3G) was detected only in black soybean crackers, and all baking treatments significantly decreased C3G. The greatest losses occurred at the low temperature×long time and high temperature×short time, the smallest loss with moderate temperature×short/medium time. The high temperature treatment altered phenolic acid and isoflavone profiles; however, total isoflavones were unaffected. Overall results suggest that moderate baking temperature at minimal time may best preserve anthocyanin and other phenolics in baked black soybean crackers.

  15. Determination of the relative contribution of quercetin and its glucosides to the antioxidant capacity of onion by cyclic voltammetry and spectrophotometric methods.

    PubMed

    Zielinska, Danuta; Wiczkowski, Wieslaw; Piskula, Mariusz Konrad

    2008-05-28

    This paper describes the use of cyclic voltammetry (CV), spectrophotometric methods [Trolox equivalent antioxidant capacity (TEAC), peroxyl radical trapping capacity (PRTC), DPPH radical scavenging activity (RSA), and Folin-Ciocalteu reagent (FCR) reducing capacity], and photochemiluminescence (PCL) for the measurement of the antioxidant capacity of onion var. Sochaczewska and var. Szalotka. The antioxidant and reducing activity of the dominant onion flavonoids quercetin (Q), quercetin-3- O-beta-glucoside (Q3G), quercetin-4'- O-beta-glucoside (Q4'G), and quercetin-3,4'-di- O-beta-glucoside (Q3,4'G) were determined by spectrophotometric (TEAC and PRTC) and CV methods, respectively. The contribution of quercetin and its glucosides to the antioxidant capacity of onion was calculated in consequence of the qualitative and quantitative analysis of onion flavonoids by high-performance liquid chromatography-ultraviolet-mass spectrometry. The dominant forms of quercetin in the onion var. Sochaczewska and Szalotka included Q4'G (61 and 54%), Q3,4'G (37 and 44%), Q3G (1.4 and 1.1%), and free quercetin (1.1 and 0.7%), respectively. The CV experiment showed the highest reducing activity of Q while Q3G, Q4'G, and Q3,4'G exhibited about 68, 51, and 30% of the reducing power noted for Q. The order of the reducing activity of onion flavonoids was confirmed by their free radical scavenging activity and evaluated by TEAC and PRTC assays as follows: Q > Q3G > Q4'G > Q3,4'G. The Q4'G and Q3,4'G showed poor antioxidant activity under both applied spectrophotometric assays but still exhibited reducing activity based on CV experiments. The reducing capacity of onions determined by CV method was twice higher than the antioxidant capacity formed by water-soluble compounds (ACW) evaluated by PCL, and it was about 50% higher than PRTC and DPPH RSA results and the converted FCR reducing capacity. In contrast, the reducing capacity of onions determined by the CV method was 3-fold and about four

  16. [Studies on effects of calycosin-7-O-β-D-glucoside on prim-O-glucosylcimifugin and cimifugin in vivo pharmacokinetics].

    PubMed

    Zhao, Xiao-Li; Liu, Ling; Di, Liu-Qing; Li, Jun-Song; Kang, An

    2014-12-01

    Study on the effects of Astragali Radix main active flavone calycosin-7-O-β-D-glucoside on Saposhnikoviae Radix main active ingredients prim-O-glucosylcimifugin and cimifugin, a UPLC-MS/MS method for simultaneous determination of prim-O-glucosylcimifugin and cimifugin in rat plasma was established, and the comparative pharmacokinetics of prim-O-glucosylcimifugin and cimifugin after oral administration of prim-O-glucosylcimifugin and calycosin-7-O-β-D-glucoside-prim-O-glucosylcimifugin to rats were carried out, which might be conductive in exploring the rationality of Astragali Radix - Saposhnikoviae Radix herb couple. Twelve male SD rats were divided into two groups. Prim-O-glucosylcimifugin and cimifugin in rat plasma of different time points after oral administration of prim-O-glucosylcimifugin and calycosin-7-O-β-D-glucoside - prim-O-glucosylcimifugin to rats were determinated. And the main pharmacokinetic parameters were investigated using DAS 3. 2. 4. The established method was rapid, accurate and sensitive for simultaneous determination of prim-O-glucosylcimifugin and cimifugin in rat plasma. The analysis was performed on a Waters Acquity BEH C18 column (2.1 mm x 100 mm, 1.7 μm) with the mixture of acetonitrile and 0.1% formic acid/water as mobile phase, and the gradient elution at a flow rate of 0.3 mL x min(-1). The analytes were detected by tandem mass spectrometry with the electrospray ionization (ESI) source and in the multiple reaction monitoring (MRM) mode. Compared with prim-O-glucosylcimifugin group, the AUC(0-t)., and AUC(0-∞) of p-O-glucosylcimifugin as well as the C(max) of cimifugin significantly increased (P < 0.05) in calycosin-7-O-β-D-glucoside-prim-O-glucosylcimifugin group. Calycosin-7-O-β-D-glucoside could enhance the absorption of prim-O-glucosylcimifugin and cimifugin and improve the bioavailability, explaining preliminarily the rationality of Astragali Radix-Saposhnikoviae Radix herb couple.

  17. Molecular theory of dielectric relaxation in nematic dimers

    NASA Astrophysics Data System (ADS)

    Stocchero, M.; Ferrarini, A.; Moro, G. J.; Dunmur, D. A.; Luckhurst, G. R.

    2004-10-01

    This paper reports a theory for the dielectric relaxation of dimeric mesogenic molecules in a nematic liquid crystal phase. Liquid crystal dimers consist of two mesogenic groups linked by a flexible chain. Recent experimental studies [D. A. Dunmur, G. R. Luckhurst, M. R. de la Fuente, S. Diez, and M. A. Perez Jubindo, J. Chem. Phys. 115, 8681 (2001)] of the dielectric properties of polar liquid crystal dimers have found unexpected results for both the static (low frequency) and variable frequency dielectric response of these materials. The theory developed in this paper provides a quantitative model with which to understand the observed experimental results. The mean-square dipole moments of α,ω-bis[(4-cyanobiphenyl-4'-yl]alkanes in a nematic phase have been calculated using both the rotational isomeric state model and a full torsional potential for the carbon-carbon bonds of the flexible chain. The orienting effect of the nematic phase is taken into account by a parametrized potential of mean torque acting on the mesogenic groups and the segments in the flexible chain. Results of calculations using the full torsional potential are in excellent agreement with experimental results for comparable systems. The probability density peq(βA,βB) for the orientation of the mesogenic groups (A,B) along the nematic director is also calculated. The resultant potential of mean torque is a surface characterized by four deep energy wells or sites equivalent to alignment of the terminal groups A and B approximately parallel and antiparallel to the director; of course, the reversal of the director leads to equivalent sites. This potential energy surface provides the basis for a kinetic model of dielectric relaxation in nematic dimers. Solution of the Fokker-Planck equation corresponding to this four-site model gives the time dependence of the site populations, and hence the time-correlation functions for the total dipole moment along the director. In this model the end

  18. Integral equation study of soft-repulsive dimeric fluids

    NASA Astrophysics Data System (ADS)

    Munaò, Gianmarco; Saija, Franz

    2017-03-01

    We study fluid structure and water-like anomalies of a system constituted by dimeric particles interacting via a purely repulsive core-softened potential by means of integral equation theories. In our model, dimers interact through a repulsive pair potential of inverse-power form with a softened repulsion strength. By employing the Ornstein–Zernike approach and the reference interaction site model (RISM) theory, we study the behavior of water-like anomalies upon progressively increasing the elongation λ of the dimers from the monomeric case (λ =0 ) to the tangent configuration (λ =1 ). For each value of the elongation we consider two different values of the interaction potential, corresponding to one and two length scales, with the aim to provide a comprehensive description of the possible fluid scenarios of this model. Our theoretical results are systematically compared with already existing or newly generated Monte Carlo data: we find that theories and simulations agree in providing the picture of a fluid exhibiting density and structural anomalies for low values of λ and for both the two values of the interaction potential. Integral equation theories give accurate predictions for pressure and radial distribution functions, whereas the temperatures where anomalies occur are underestimated. Upon increasing the elongation, the RISM theory still predicts the existence of anomalies; the latter are no longer observed in simulations, since their development is likely precluded by the onset of crystallization. We discuss our results in terms of the reliability of integral equation theories in predicting the existence of water-like anomalies in core-softened fluids.

  19. A Uranyl Peroxide Dimer in the Gas Phase.

    PubMed

    Dau, Phuong D; Dau, Phuong V; Rao, Linfeng; Kovács, Attila; Gibson, John K

    2017-04-03

    The gas-phase uranyl peroxide dimer, [(UO2)2(O2)(L)2](2+) where L = 2,2'-trifluoroethylazanediyl)bis(N,N'-dimethylacetamide), was synthesized by electrospray ionization of a solution of UO2(2+) and L. Collision-induced dissociation of this dimer resulted in endothermic O atom elimination to give [(UO2)2(O)(L)2](2+), which was found to spontaneously react with water via exothermic hydrolytic chemisorption to yield [(UO2)2(OH)2(L)2](2+). Density functional theory computations of the energies for the gas-phase reactions are in accord with observations. The structures of the observed uranyl dimer were computed, with that of the peroxide of particular interest, as a basis to evaluate the formation of condensed phase uranyl peroxides with bent structures. The computed dihedral angle in [(UO2)2(O2)(L)2](2+) is 145°, indicating a substantial deviation from the planar structure with a dihedral angle of 180°. Energies needed to induce bending in the most elementary gas-phase uranyl peroxide complex, [(UO2)2(O2)](2+), were computed. It was found that bending from the lowest-energy planar structure to dihedral angles up to 140° required energies of <10 kJ/mol. The gas-phase results demonstrate the inherent stability of the uranyl peroxide moiety and support the notion that the uranyl-peroxide-uranyl structural unit is intrinsically planar, with only minor energy perturbations needed to form the bent structures found in studtite and uranyl peroxide nanostructures.

  20. Dimerization and DNA recognition rules of mithramycin and its analogues

    PubMed Central

    Weidenbach, Stevi; Hou, Caixia; Chen, Jhong-Min; Tsodikov, Oleg V.; Rohr, Jürgen

    2016-01-01

    The antineoplastic and antibiotic natural product mithramycin (MTM) is used against cancer-related hypercalcemia and, experimentally, against Ewing sarcoma and lung cancers. MTM exerts its cytotoxic effect by binding DNA as a divalent metal ion (Me2+)-coordinated dimer and disrupting the function of transcription factors. A precise molecular mechanism of action of MTM, needed to develop MTM analogues selective against desired transcription factors, is lacking. Although it is known that MTM binds G/C-rich DNA, the exact DNA recognition rules that would allow one to map MTM binding sites remain incompletely understood. Towards this goal, we quantitatively investigated dimerization of MTM and several of its analogues, MTM SDK (for Short side chain, DiKeto), MTM SA-Trp (for Short side chain and Acid), MTM SA-Ala, and a biosynthetic precursor premithramycin B (PreMTM B), and measured the binding affinities of these molecules to DNA oligomers of different sequences and structural forms at physiological salt concentrations. We show that MTM and its analogues form stable dimers even in the absence of DNA. All molecules, except for PreMTM B, can bind DNA with the following rank order of affinities (strong to weak): MTM = MTM SDK > MTM SA-Trp > MTM SA-Ala. An X(G/C)(G/C)X motif, where X is any base, is necessary and sufficient for MTM binding to DNA, without a strong dependence on DNA conformation. These recognition rules will aid in mapping MTM sites across different promoters towards development of MTM analogues as useful anticancer agents. PMID:26760230