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Results 251 - 300 of 1405
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Sakamoto Tsubasa - - 2012
By use of 2-deuterated benzothiazoline as a deuterium donor in combination with a chiral phosphoric acid, the transfer deuteration of ketimine and α-iminoester took place smoothly to give α-deuterated amines in high yields with excellent enantioselectivities. The remarkable kinetic isotope effect suggests that carbon-deuterium bond cleavage is the rate-determining step.
Dong Jing Z - - 2012
BACKGROUND: Leaves of Lycium chinense L. are widely used in traditional Chinese medicine and as functional food in China and south-east Asia. Polyphenols are important active compounds in leaves of L. chinense L, but their compositions are still not very clear. Selenium has been reported to increase some components of ...
Deng Ke-Qin - - 2012
Directly electrochemically reduced graphene oxide (ERGO) was obtained by potentiostatic reduction of exfoliated graphene oxide sheets on a glassy carbon electrode (GCE). The ERGO-modified electrode (ERGO/GCE) displayed greatly improved voltammetric response to the amino acids l-tryptophane (Trp) and l-tyrosine (Tyr) compared with the chemically reduced graphene oxide (CRGO) modified electrode. ...
Vasić Milica - - 2012
Graphite modified with gallic acid to form 'gallic acid-carbon' is demonstrated to be efficient for the removal of bismuth(iii) ions from aqueous solutions. The uptake is demonstrated to be rapid but not to follow standard adsorption isotherm models. Instead, the uptake was found to be further promoted by the presence ...
Ding Wenbing - - 2012
Three glycosidic acids, turpethic acids A-C, and two intact resin glycosides, turpethosides A and B, all having a common pentasaccharide moiety and 12-hydroxy fatty acid aglycones of different chain lengths, were obtained from the aerial parts of Operculina turpethum. Their structures were elucidated by spectroscopic analyses and chemical correlations. The ...
Aura Anna-Marja - - 2012
PURPOSE: Syrah red grapes are used in the production of tannin-rich red wines. Tannins are high molecular weight molecules, proanthocyanidins (PAs), and poorly absorbed in the upper intestine. In this study, gut microbial metabolism of Syrah grape phenolic compounds was investigated. METHODS: Syrah grape pericarp was subjected to an enzymatic ...
Li Qingling - - 2012
The catabolism of 4-hydroxy acid (drugs of abuse and lipid peroxidation products) generates a series of hydroxy acids with different carbon chain lengths and hydroxyl group at different locations. The identification of these hydroxy acid metabolites is important to uncover the catabolic pathways of drugs of abuse and lipid peroxidation ...
Khandelwal Manish - - 2012
The strong Lewis acid [Et(2) Al](+) catalyzes the reduction of carbon dioxide with hydrosilanes under mild conditions to methane. In benzene solution, the side products toluene and diphenylmethane are also obtained through Lewis acid catalyzed benzene alkylation by reaction intermediates.
Zhang Fan - - 2012
Natural products possessing the 3-(furan-2(5H)-ylidene)furan-2,4(3H,5H)-dione (furylidene tetronic acid) skeleton are rare and were encountered only as fungal metabolites. The configurational assignment of the furylidene tetronic acid core using conventional approaches remained a challenge. Pestalotic acids A-G () are new furylidene tetronic acid derivatives isolated from a plant endophyte Pestalotiopsis yunnanensis. ...
Wu Zhijun - - 2012
Two new phenolic glycosides were isolated from the ethanol extract of the roots of Inula cappa DC. Their structures were defined as 4-[(6-O-(E)-caffeoyl)-β-D-glucopyranosyl]vanillic acid (1) and 3-O-[β-D-apiofurarnosyl-(1-6)-β-D-glucopyranoxy]-6-hydroxy-p-cymene (2) on the basis of spectral analysis.
Dorion Sonia - - 2012
Triosephosphate isomerase (TPI, EC 5.3.1.1) catalyzes the interconversion of dihydroxyacetone-P and glyceraldehyde 3-P in the glycolytic pathway. A constitutively expressed antisense construct for cytosolic TPI was introduced into potato (Solanum tuberosum) using Agrobacterium rhizogenes to examine the metabolic effects of a reduction in cytosolic TPI in roots. We obtained a ...
Bhadra Sukalyan - - 2012
Decarboxylative Chan-Evans-Lam-type couplings are presented as a new strategy for the regiospecific construction of diaryl and alkyl aryl ethers starting from easily available aromatic carboxylic acids. They allow converting various aromatic carboxylate salts into the corresponding aryl ethers by reaction with alkyl orthosilicates or aryl borates, under aerobic conditions in ...
Serrato Rodrigo V - - 2012
Lipid-A was isolated by mild acid hydrolysis from lipopolysaccharides extracted from cells of Herbaspirillum seropedicae, strain SMR1, and from two mutants deficient in the biosynthesis of rhamnose (rmlB(-) and rmlC(-)). Structural analyses were carried out using MALDI-TOF and derivatization by per-O-trimethylsilylation followed by GC-MS in order to determine monosaccharide and ...
He Zhi - - 2012
A reaction exemplifying migration of a carbon-boron bond is described. We show that α-boroalkyl groups of transient boroalkyl acyl azide intermediates readily migrate from carbon to nitrogen. This process allows access to a new class of stable molecules, α-boryl isocyanates, from α-boryl carboxylic acid precursors. The methodology facilitates synthesis of ...
Wang Jun - - 2012
Three isomers of mono-caffeoylquinic acid, specifically, 3-O-caffeoylquinic acid, 4-O-caffeoylquinic acid and 5-O-caffeoylquinic acid, were successfully isolated from a crude extract of tobacco (Nicotiana tobaccum L.) wastes using continuous resin-based pre-separation and preparative high-performance liquid chromatography (HPLC). The extract of tobacco wastes was continuously pre-separated by resin-based columns packed with D101 ...
Ceborska Magdalena - - 2012
The formation of different complexes of folic acid depending on the size of the host cyclodextrin resulting in either an exclusion compound (with the smallest α-cyclodextrin) or 2-rotaxane, where cyclodextrin is threaded over folic acid (with β- and γ-cyclodextrins), is presented. The formation is carried out in water which allows ...
Riaz Naheed - - 2012
Four new sphingolipids: nudicaulin A [(2S,3S,4R,14E)-2-{[octadecanoyl]amino}tetraeicos-14-ene-1,3,4-triol; 1], nudicaulin B [(2S,3S,4R,14E)-2-{[(2R)-2-hydroxyoctadecanoyl]amino}tetraeicos-14-ene-1,3,4-triol; 2], nudicaulin C [(2S,3S,4R,14E)-2-{[(2R)-2-hydroxyoctadecanoyl]amino}tetraeicos-14-ene-1,3,4-triol-1-O-β-d-glucopyranoside; 3], and nudicaulin D [(2S,3S,4R)-2-{[(2R,3S,12E)-2,3-dihydroxyeicos-12-enoyl]amino}octadecane-1,3,4-triol; 4] together with 1-hexatriacontanol, β-sitosterol, octadecyl 4-hydroxycinnamate, elaidic acid, cholesta-5,22-diene-3,7-diol, oleanolic acid, apigenin, and β-sitosterol 3-O-β-d-glucopyranoside were isolated from the methanolic extract of the whole plant of Launaea nudicaulis. Their structures ...
Xing Yan - - 2012
In the current study, caffeic acid was an important metabolite in the highly copper-tolerant plant Elsholtzia splendens. Preparation and purification of caffeic acid were performed on the dried biomass of the plants by means of sonication/ethanol extraction, followed by purification using a macroporous resin (D101 type) column and silica gel ...
Muñoz Marcelo A - - 2012
The relative stereochemistry at C13 and the absolute configuration of salvic acid, a constituent of the leaves of Eupatorium salvia, were established as the 13-(R)-ent-labdane 1. The results follow from vibrational circular dichroism measurements of the derived O-methyl ether methyl ester 3 which were compared to DFT B3LYP/DGDZVP calculated spectra. ...
Jones David D Petroleum and Environmental Geochemistry Group, Biogeochemistry Research Centre, University of Plymouth, Drake Circus, Plymouth PL4 8AA, - - 2012
The naphthenic acids of oil sands process-affected water (OSPW) are said to be important toxicants. The major acids are stated to have alicyclic structures and recently, numerous of these have been identified, but some evidence suggests 'aromatic' acids are also present. The proportions of such acids have not been reported ...
Ohdate Takumi - - 2012
Saccharomyces cerevisiae is able to use some fatty acids, such as oleic acid, as a sole source of carbon. β-Oxidation, which occurs in a single membrane-enveloped organelle or peroxisome, is responsible for the assimilation of fatty acids. In S. cerevisiae, β-oxidation occurs only in peroxisomes, and H(2)O(2) is generated during ...
Gandía-Herrero Fernando - - 2012
Betalamic acid [4-(2-oxoethylidene)-1,2,3,4-tetrahydropyridine-2,6-dicarboxylic acid] is a naturally occurring compound that is normally found condensed with amino acids, amines, cyclo-DOPA, and cyclo-DOPA derivatives to form the betalains. Betalains are the pigments responsible for the yellow to violet color of the fruits and flowers of plants belonging to the order Caryophyllales. Betalamic ...
Liu Huihui - - 2012
The polysaccharides from the fruits of Lycium barbarum have received considerable attention in previous publication, but the polysaccharides from the leaves were rarely reported. In the present work, four water-soluble polysaccharide fractions: LBP-I, LBP-II, LBP-III and LBP-IV isolated from Lycium barbarum leaves were purified through DEAE-Sephadex A-25. LBP-II and LBP-IV ...
Al-Mekhlafi Nabil Ali - - 2012
Phytochemical investigation on the leaves of Labisia pumila (Myrsinaceae), an important medicinal herb in Malaysia, has led to the isolation of 1-O-methyl-6-acetoxy-5-(pentadec-10Z-enyl)resorcinol (1), labisiaquinone A (2) and labisiaquinone B (3). Along with these, 16 known compounds including 1-O-methyl-6-acetoxy-5-pentadecylresorcinol (4), 5-(pentadec-10Z-enyl)resorcinol (5), 5-(pentadecyl)resorcinol (6), (-)-loliolide (7), stigmasterol (8), 4-hydroxyphenylethylamine (9), 3,4,5-trihydroxybenzoic ...
Lindenkamp Nicole - - 2012
β-Ketothiolases catalyze the first step of poly(3-hydroxybutyrate) [poly(3HB)] biosynthesis in bacteria by condensation of two acetyl coenzyme A (acetyl-CoA) molecules to acetoacetyl-CoA and also take part in the degradation of fatty acids. During growth on propionate or valerate, Ralstonia eutropha H16 produces the copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [poly(3HB-co-3HV)]. In R. eutropha, 15 ...
Wang Li-Juan - - 2012
In this paper, twelve dialkyltartrate-boric acid complexes and two polyols-boric acid complexes were in situ synthesized by the reaction of different dialkyltartrates or polyols with boric acid in methanol containing triethylamine. All of the twelve dialkyltartrate-boric acid complexes were found to have relatively good chiral separation performance in nonaqueous capillary ...
Westfall Corey S - - 2012
Acyl acid amido synthetases of the GH3 family act as critical prereceptor modulators of plant hormone action; however, the molecular basis for their hormone selectivity is unclear. Here, we report the crystal structures of benzoate-specific Arabidopsis thaliana AtGH3.12/PBS3 and jasmonic acid (JA)-specific AtGH3.11/JAR1. These structures, combined with biochemical analysis, define ...
Zhang Yu - - 2012
A novel material, sol-gel derived La(OH)(3) nanorods (La(OH)(3)NRs) with excellent film forming ability was prepared, and it was first designed to incorporate with carbon nanotubes (CNTs) to modify glassy carbon electrode (GCE) to simultaneously voltammetric determine ascorbic acid (AA), dopamine (DA), uric acid (UA), and nitrite (NO(2)(-)). Cyclic voltammetry (CV), ...
Gupta Prasoon - - 2012
Three new bicyclic C(21) terpenoids, clathric acid (1) and two N-acyl taurine derivatives, clathrimides A (2) and B (3), were isolated from the marine sponge Clathria compressa. The structures of these compounds were elucidated by interpretation of spectroscopic data. Clathric acid showed mild antibacterial activity against several Gram-positive bacteria.
Efdi Mai - - 2012
A new ring A-seco triterpenoid, sentulic acid, along with a known oleanane-type triterpenoid, 3-oxoolean-12-en-27-oic acid, were isolated from the Indonesian plant Sandoricum koetjape Merr. Their chemical structures were elucidated by spectroscopic analysis. In addition, the cytotoxic effects of these compounds on human promyelocytic leukemia HL-60 cells were studied. The results ...
Carta Fabrizio - - 2012
Using hydroxy-/dihydroxybenzoic acids as leads, a series of methyl, ethyl and iso-propyl esters of 4-hydroxy-benzoic acid, 2,4-, 2,5-, 2,6-, 3,4-, and 3,5-dihydroxybenzoic acids and of coumaric acid, were obtained and investigated for the inhibition of six mammalian carbonic anhydrase (CA, EC 4.2.1.1) isoforms, that is, the cytosolic CA I, II ...
Kenny Shane T - - 2012
Sodium terephthalate (TA) produced from a PET pyrolysis product and waste glycerol (WG) from biodiesel manufacture were supplied to Pseudomonas putida GO16 in a fed-batch bioreactor. Six feeding strategies were employed by altering the sequence of TA and WG feeding. P. putida GO16 reached 8.70 g/l cell dry weight (CDW) and ...
Kim Sang Min - - 2012
Ligularia fischeri (Ledeb.) Turcz, a commercial leafy vegetable, contains caffeoylquinic acid derivatives (CQAs) as major phenolic constituents. The HPLC chromatograms of leaf extracts collected from different areas in Korea showed a significant variation in CQA amount and two tri-O-caffeoylquinic acids (triCQAs) were purified and structurally identified by NMR and MS ...
Igarashi Yasuhiro - - 2012
Jomthonic acid A (1), a new modified amino acid, was isolated from the culture broth of a soil-derived actinomycete of the genus Streptomyces. The structure and absolute configuration of 1 were determined by spectroscopic analyses and chemical conversion. Jomthonic acid A (1) induced differentiation of preadipocytes into mature adipocytes at ...
Loyola-Vargas Victor - - 2012
Methyl jasmonate (MeJA) produces an important reduction in the accumulation of proteins related to energy metabolism. The treatment of hairy roots (HR) with MeJA increased the accumulation of H2O2 during the first 48 h and this H2O2 accumulation was also observed in isolated mitochondria. Peroxidase and catalase activities decreased in ...
Esbaugh Andrew J - - 2012
The oceanic carbonate system is changing rapidly due to rising atmospheric CO(2), with current levels expected to rise to between 750 and 1,000 μatm by 2100, and over 1,900 μatm by year 2300. The effects of elevated CO(2) on marine calcifying organisms have been extensively studied; however, effects of imminent CO(2) levels ...
Ritota Mena - - 2012
(1)H High Resolution Magic Angle Spinning-Nuclear Magnetic Resonance (HRMAS-NMR) spectroscopy was used to analyse garlic (Allium sativum L.) belonging to red and white varieties and collected in different Italian regions, in order to address the traceability issue. 1D and 2D NMR spectra, performed directly on untreated small pieces of garlic, ...
Ping Jianfeng - - 2012
A novel carbon composite electrode consisted of ionic liquid n-octylpyridinum hexafluorophosphate (OPFP) and single-walled carbon nanotube (SWCNT) was fabricated and investigated. This electrode combined the advantages of ionic liquid and SWCNT together with the "bulk" composite electrode. Compared with other composite electrodes using graphite or paraffin oil, the ionic liquid-SWCNT ...
Wang Y - - 2012
Bio-inspired chemical approach has been developed for the surface modification and electrophoretic deposition of manganese dioxide and zirconia nanoparticles, prepared by chemical precipitation methods. Caffeic acid, trans-cinnamic acid, p-coumaric acid, and 2,4-dihydroxycinnamic acid were investigated for the surface modification of the nanoparticles. The influence of the structure of the organic ...
Evans Amanda C - - 2012
The primordial appearance of chiral amino acids was an essential component of the asymmetric evolution of life on Earth. In this tutorial review we will explore the original life-generating, symmetry-breaking event and summarise recent thoughts on the origin of enantiomeric excess in the universe. We will then highlight the transfer ...
Zheng Yong-Biao - - 2012
Two new and three known abscisic acid-related metabolites were obtained from the potato dextrose agar culture of Phellinus vaninii YB2005. Their structures were established on the basis of detailed spectroscopic analyses, including 1D NMR, 2D NMR, and HR-Q-TOF-MS techniques. The putative biosynthesis pathway of these secondary metabolites would decipher the ...
Al-Jaber Hala I - - 2012
The novel seco-ursane-type triterpenoid 3β,11α-dihydroxy-17,22-seco-17(28), 12-ursadien-22-oic acid (1) was isolated for the first time from a natural source from two Salvia species growing wild in Jordan, Salvia palaestina Benth. and Salvia syrica L. In addition to compound 1, S. syriaca afforded a new sesquiterpene named syriacine (2). S. palaestina also ...
Peng Xuewei - - 2012
The degradation of three phthalic acid esters (PAEs) (dimethyl phthalate (DMP), diethyl phthalate (DEP) and di-n-butyl phthalate (DBP)) by natural microbial community under aerobic condition and their isotope fractionation were compared by using a laboratory microcosm system with natural marine sediment overlying with natural seawater. The results showed that the ...
Akien Geoffrey R - - 2012
Several intermediates and different reaction paths were identified for the acid catalysed conversion of fructose to 5-(hydroxymethyl)-2-furaldehyde (HMF) in different solvents. The structural information combined with results of isotopic-labelling experiments allowed the determination of the irreversibility of the three steps from the fructofuranosyl oxocarbenium ion to HMF as well as ...
Heckler James E - - 2012
The electrophilic [Ph(3) PAu]NTf(2) quickly diaurates aryl boronic acids providing stable geminally diaurated complexes (see example; yellow, Au; orange, P; blue, C) that have been spectroscopically, and in some cases crystallographically, characterized. Geminally diaurated arenes are putative intermediates in gold(I) catalysis and are analogues of Wheland intermediates of electrophilic aromatic ...
Huo Hua - - 2012
17O-1H double resonance NMR spectroscopy was used to study the local structure of zeolite H-Mordenite. Different contact times were used in cross polarization magic angle spinning (CPMAS) NMR, CP rotational-echo double resonance (CP-REDOR) NMR and heteronuclear correlation (HETCOR) NMR spectroscopy to distinguish between Brønsted acid sites with different O-H distances. ...
Rama Gustavo - - 2012
Playing into our hands: The achiral bipyridine amino acid fluorenylmethyoxlcarbonyl 5-amino-3-oxapentanoic acid (Fmoc-O1PenBpy-OH) has been used for the solid-phase synthesis of metallopeptides. Circular dichroism, molecular modeling, and NMR spectroscopic studies show that the chirality of the resulting metal complexes in aqueous solution is determined, and can thus be controlled, by ...
de Clippel Filip - - 2012
A novel catalyst design for the conversion of mono- and disaccharides to lactic acid and its alkyl esters was developed. The design uses a mesoporous silica, here represented by MCM-41, which is filled with a polyaromatic to graphite-like carbon network. The particular structure of the silica-carbon composite allows the accommodation ...
Shashkov A S - - 2012
The cell wall of Actinoplanes utahensis VKM Ac-674(T) contains two anionic polymers: teichoic acid 1,3-poly(glycerol phosphate) that is widespread in cell walls of Gram-positive bacteria; and a unique teichulosonic acid belonging to a new class of bioglycans described only in microorganisms of the Actinomycetales order. The latter polymer contains residues of ...
Sirisoontorn Irin - - 2012
The effect of zoledronic acid, a potent and novel bisphosphonate, on tooth movement and orthodontically induced root resorption in osteoporotic animals systemically treated with zoledronic acid as similarly used in postmenopausal patients has not been elucidated. Therefore, this study was undertaken. Fifteen 10-week-old female Wistar rats were divided into 3 ...
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