Search Results
Results 251 - 300 of 1685
< 1 2 3 4 5 6 7 8 9 10 11 >
Guzman Marcelo I - - 2009
A reductive tricarboxylic acid (rTCA) cycle could have fixed carbon dioxide as biochemically useful energy-storage molecules on early Earth. Nonenzymatic chemical pathways for some steps of the rTCA cycle, however, such as the production of the alpha-ketocarboxylic acids pyruvate and alpha-ketoglutarate, remain a challenging problem for the viability of the ...
Kodera Tomohiro - - 2009
The unique function of 4-hydroxyisoleucine (4-HIL) is to stimulate glucose-induced insulin secretion in a glucose-dependent manner. 4-HIL is distributed only in certain kinds of plants and mushrooms, but the biosynthetic mechanism of 4-HIL has not been elucidated. Moreover, 4-HIL-producing microorganisms have not been reported. l-isoleucine (l-Ile) hydroxylating activity producing 4-HIL ...
Ju Xin - - 2010
Substrate-directed screening was carried out to find bacteria that could deacylate O-acetylated mandelic acid from environmental samples. From more than 200 soil isolates, we identified for the first time that Pseudomonas sp. ECU1011 biocatalytically deacylated (S)-alpha-acetoxyphenylacetic acid with high enantioselectivity (E > 200), yielding (S)-mandelic acid with 98.1% enantiomeric excess ...
Adisakwattana Sirichai - - 2009
Inhibition of alpha-glucosidase and alpha-amylase delays the digestion of starch and disaccharides to absorbable monosaccharides, resulting in a reduction of postprandial hyperglycemia. Finding effective mammalian alpha-glucosidase inhibitors from natural sources can be beneficial in the prevention and treatment of diabetes mellitus. We investigated the inhibitory activity of cinnamic acid derivatives ...
Fonseca I - - 2009
The photoreaction of two alpha-cinnamic acid derivatives, alpha-o-methoxy and alpha-o-ethoxy cinnamic acid, was studied by (13)C CPMAS solid-state NMR spectroscopy in order to elucidate effects of aromatic substitution and substituent size on the kinetics of the [2+2] photodimerization. The reactants and products can be clearly differentiated and a detailed spectroscopic ...
Troyer Timothy L - - 2009
A novel alpha-diazo imide reagent and its activation by strong Brønsted acid is shown to produce the product of a syn-glycolate Mannich transform with high diastereoselection.
Park Yohan - - 2009
An efficient enantioselective synthetic method for (S)-alpha-alkyl-alpha,beta-diaminopropionic acid is reported. The asymmetric phase-transfer catalytic alkylation of N(1)-Boc-2-phenyl-2-imidazoline-4-carboxylic acid tert -butyl ester in the presence of chiral quaternary ammonium catalyst gave the corresponding alkylated products (93-98% ee) which could be transformed to enantioenriched alpha-alkyl-alpha,beta-diaminopropionic acids.
Fowler Lindsay S - - 2009
The development of a facile and general method for the preparation of enone derived alpha-amino acids is described. The key step involves a Horner-Wadsworth-Emmons reaction between an aspartic acid derived beta-keto phosphonate ester and a range of aldehydes resulting in the formation of highly functionalised alpha-amino acids in good yields. ...
Poeckel Daniel - - 2009
Pirinixic acid (Wy-14,643) is an agonist of the peroxisome proliferator-activated receptor (PPAR) subtype alpha exhibiting beneficial effects in various inflammation-related processes in a slow, long-termed fashion. We recently showed that alpha-substituted pirinixic acid derivatives are agonists of PPAR alpha and act as dual inhibitors of 5-lipoxygenase (5-LO, EC 1.13.11.34) and ...
Shay Kate Petersen - - 2009
Alpha-lipoic acid (LA) has become a common ingredient in multivitamin formulas, anti-aging supplements, and even pet food. It is well-defined as a therapy for preventing diabetic polyneuropathies, and scavenges free radicals, chelates metals, and restores intracellular glutathione levels which otherwise decline with age. How do the biochemical properties of LA ...
Lee Woo Yong WY Department of Anesthesiology and Pain Medicine InJe University, Sanggyepaik Hospital, Seoul 139-707, South - - 2009
Alpha-lipoic acid (1,2-dithiolane-3-pentanoic acid; lipoic acid) is an endogenous compound used to treat pain disorders in humans, but its mechanisms of analgesic action are not well understood. Here, we show that lipoic acid selectively inhibited native Ca(V)3.2 T-type calcium currents (T-currents) and diminished T-channel-dependent cellular excitability in acutely isolated rat ...
Richard John P JP Department of Chemistry, University at Buffalo, State University of New York, Buffalo, NY 14260-3000, USA. - - 2009
Studies of nonenzymatic electrophilic catalysis of carbon deprotonation of glycine show that pyridoxal 5'-phosphate (PLP) strongly enhances the carbon acidity of alpha-amino acids, but that this is not the overriding mechanistic imperative for cofactor catalysis. Although the fully protonated PLP-glycine iminium ion adduct exhibits an extraordinary low alpha-imino carbon acidity ...
He Panqing - - 2009
4-Hydroxyphenylpyruvate dioxygenase (HPPD) and hydroxymandelate synthase (HMS) are the only two known members of the alpha-keto acid-dependent oxygenases that adopt the fold common to the vicinal oxygen chelate superfamily of enzymes. All other oxygenases of this type have a jellyroll fold. Despite a clearly different ancestry, the salient details of ...
Stabler Sally P SP Department of Medicine and Division of Hematology, University of Colorado at Denver and Health Sciences Center, Aurora, CO 80045, USA. - - 2009
Lipoic acid is a disulfhydryl-containing compound used in clinical medicine and in experimental models as an antioxidant. We developed a stable isotope dilution capillary gas chromatography/mass spectrometry assay for lipoic acid. We assayed a panel of the metabolites of transmethylation and transsulfuration 30 min after injecting 100 mg/kg lipoic acid ...
Narendra N - - 2009
Application of the Lossen rearrangement to the synthesis of N-urethane protected alpha-peptidyl ureas and ureidopeptides is reported. The carbodiimide mediated rearrangement of N-Boc/Z/Fmoc protected alpha-amino/peptide hydroxamic acids into isocyanates and coupling of the latter with the amino acid esters/peptide esters have been accomplished in a single-pot to obtain good yields ...
Caballero Isabel - - 2009
While beer provides a very stable microbiological environment, a few niche microorganisms are capable of growth in malt, wort, and beer. The production of off-flavors and development of turbidity in the packaged product are due to the growth and metabolic activity of wild yeast, certain lactic acid bacteria (LAB) and ...
Lee Jeong-In JI Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY 10595, - - 2009
Histone deacetylase (HDAC) inhibitors are gaining interest as cancer therapeutic agents. We tested the hypothesis that natural organoselenium compounds might be metabolized to HDAC inhibitors in human prostate cancer cells. Se-Methyl-L-selenocysteine (MSC) and selenomethionine are amino acid components of selenium-enriched yeast. In a cell-free system, glutamine transaminase K (GTK) and ...
Débieux Jean-Luc - - 2009
A range of N-protected-alpha-amino acyl-5,7-dinitroindolines 3a-z were prepared in good yields from commercially available N-protected-alpha-amino acids 1a-z by a two-step sequence of acylation and intramolecular amide N-arylation. Subsequent photochemical acylation of the N-protected-alpha-amino acyl-5,7-dinitroindolines 3e,g,r afforded the corresponding N-protected-alpha-amino acid amides 22e,g,r (77-92%) under mild conditions. All these reactions occurred ...
Ura Yasuyuki - - 2009
We describe the preparation and characterization of polythioesters composed of alternating alpha-amino acid and alpha-thioglycolic acid residues that undergo dynamic constitutional exchange under mild conditions. The polymers are assembled via reversible ring-opening polymerizations of 1,4-thiazine-2,5-diones and related monomers in solution-phase conditions that do not require the use of transition metal ...
Tanaka Hiroshi - - 2009
An efficient stereoselective synthesis of alpha(2,9) tetra- to disialic acids 1-3, using the 5,4-N,O-carbonyl protected thiosialoside 4, is described. The cyclic protecting group was effective for alpha-sialylation without the need for acetonitrile as the solvent. The donor 4 enabled the formation of a tetramer in excellent yield and selectivity. Deprotection ...
Kimura Kazuyoshi - - 2009
Rat Delta6 desaturase was introduced in "oleaginous" Saccharomyces cerevisiae genetically modified by the snf2 disruption, DGA1 overexpression, and LEU2 expression to improve stearidonic acid (18:4n-3 (Delta6, 9, 12, 15)) production. When this transformed yeast was cultured in the presence of 0.7 g/l alpha-linolenic acid for 7 d, 0.4 g of ...
Gallagher Renata C - - 2009
OBJECTIVE: Folinic acid-responsive seizures and pyridoxine-dependent epilepsy are two treatable causes of neonatal epileptic encephalopathy. The former is diagnosed by characteristic peaks on cerebrospinal fluid (CSF) monoamine metabolite analysis; its genetic basis has remained elusive. The latter is due to alpha-aminoadipic semialdehyde (alpha-AASA) dehydrogenase deficiency, associated with pathogenic mutations in ...
Hou Wenli - - 2009
The potential antidiabetic activity of ethyl acetate extract of the leaves of Lagerstroemia speciosa (LSL) was investigated by alpha-amylase and alpha-glucosidase inhibition assay. Six pentacyclic triterpenes (oleanolic acid, arjunolic acid, asiatic acid, maslinic acid, corosolic acid and 23-hydroxyursolic acid) were isolated from LSL. Their structures were determined by spectroscopic analysis ...
Mailloux Ryan J - - 2009
Alpha-ketoglutarate (KG) is a crucial metabolite in all living organisms, as it participates in a variety of biochemical processes. We have previously shown that this keto acid is an antioxidant and plays a key role in the detoxification of reactive oxygen species (ROS). In an effort to further confirm this ...
Balducci Daniele - - 2010
A new and convenient stereocontrolled synthesis of the optically pure (S)-alpha-methyl,alpha-amino acids 6(a-d) that exploits the chiral synthon 1,4-N,N-[(S)-1-phenylethyl]-piperazine-2,5-dione (1) is described. The (S)-1-phenylethyl group, bonded to each of the N-atoms of the 2,5-diketopiperazine, acts as a chiral inductor in the first alkylation, while the steric hindrance appears to be ...
Jia Lihong - - 2009
Acrolein is a highly reactive unsaturated hazardous air pollutant of human health concern, particularly as a component of cigarette smoke. In this study, the effects of acrolein on mitochondrial damage in IMR-90 (a human lung fibroblast cell line), and the reduction of this damage by R-alpha-lipoic acid were examined. Our ...
Liang Chien-Fu - - 2009
A new approach for the synthesis of S-linked alpha(2-->9) oligosialic acids was developed by using an asymmetric tert-butyl disulfide linkage as an anomeric thiol protecting group. Compared with conventional thiosialosides, the asymmetric disulfide sialosides can tolerate the conditions under which functional groups are modified without producing the undesired elimination and ...
Nagano Masanobu - - 2009
Two series of homooligomers composed of diastereoisomeric cyclic alpha-amino acids having two chiral centers at the alpha-carbon and the side chain were synthesized, and their preferred secondary structures were studied in solution and in the crystal state. The oligomers are a new class of helical-foldamers possessing two kinds of chiral ...
Leggio Antonella - - 2009
A study of the methylation of N-nosyl-alpha-amino acids and derivatives with trimethylsilyldiazomethane is here reported. Trimethylsilyldiazomethane allows the chemo-specific methylation of the carboxyl function of N-nosyl-alpha-amino acids in high yields and purity. This method provides a practical route to N-methyl-alpha-amino acids avoiding the use of the more toxic and explosive ...
Pilgrim Wayne - - 2009
Bacterial glycolipids containing either alpha-glucuronic acid or alpha-galacturonic acid residues have an important role in the innate-type immune response to gram-negative bacteria. Synthesis of closely related compounds, including a novel alpha-SO(2) glycolipid mimetic, is described from carbohydrate precursors where anomerization is a key step. Very high stereoselectivites (>97:3 in favor ...
Mortensen Matthew - - 2009
Amino acids serve not only as monomers for proteins and enzymes but also as important players in signal transduction pathways. They belong to the abundant feedstock of the pharmaceutical, food science and agrochemical industries, and some are used as catalysts or ligand components. In recent years, non-proteogenic amino acids have ...
Caputo Romualdo - - 2010
The synthesis of new substituted prolines carrying at C-4 a second alpha-amino acid residue is reported. The amino acid, L-cysteine or L-selenocysteine, is linked to the proline ring through the sulfur or the selenium atom, respectively. The products were prepared with different stereochemistry at C-4, in few and clean high-yielding ...
Yan Hong-de - - 2009
Kinetic resolution of alpha-lipoic acid, a case of remote stereocenter discrimination, was accomplished using lipase from Aspergillus oryzae WZ007. Performance of this lipase was investigated for enantioselective esterification of (S)-alpha-lipoic acid, leaving the target product (R)-alpha-lipoic acid in unreacted form. The effects of chain length of alcohol, type of solvent, ...
Li Zhong'an - - 2009
For the first time, a conjugated fluorescent polymer was utilized to probe alpha-amino acids, sensitively and selectively, through a new approach. First the strong fluorescence of the prepared polyfluorene (P1) was quenched by trace copper ions, and then the quenched fluorescence was recovered upon the addition of alpha-amino acids, making ...
Cativiela Carlos - - 2009
The most recent papers describing the stereoselective synthesis of cyclic quaternary alpha-amino acids are collected in this review. The diverse synthetic approaches are classified according to the size of the ring and taking into account the bond that is formed to complete the quaternary skeleton.
Iglesias Jacobo - - 2009
In an emulsion of corn oil in water with the addition of caffeic acid (Caf-OH) and alpha-tocopherol (alpha-TOH), Caf-OH was found to be very active in delaying lipid oxidation without affecting significantly the kinetics for alpha-TOH degradation. In contrast, Caf-OH addition to fish muscle retarded both the degradation of endogenous ...
Müller Jane - - 2009
The nonribosomal peptide synthetase PF1022-synthetase (PFSYN) synthesises the cyclooctadepsipeptide PF1022 from the building blocks D-lactate, D-phenyllactate and N-methylleucine. The substrate tolerance of PFSYN for hydroxy acids was probed by in vitro screening of a set of aliphatic and aromatic alpha-D-hydroxy acids with various structural modifications in the side chain. Thus, ...
Zhdanko Alexander G - - 2009
Chiral ortho esters of alpha-isocyano acids were synthesized from commercially available Cbz-protected alpha-amino acids. These compounds are stable toward racemization in the Ugi 4CC in contrast to known esters of alpha-isocyano acids. Applying them in Ugi 4CC with subsequent deprotection gives access to dipeptides with preserved configuration at the C-terminal ...
Herzog Christian C Central Arkansas Veterans Healthcare System, 4300 W. 7th Street, 111D, Little Rock, AR 72205, - - 2009
The present study demonstrates that both oligomeric metalloendopeptidase meprin A purified from kidney cortex and recombinant meprin alpha are capable of generating biologically active IL-1beta from its precursor pro-IL-1beta. Amino-acid sequencing analysis reveals that meprin A and meprin alpha cleave pro-IL-1beta at the His(115)-Asp(116) bond, which is one amino acid ...
Yamasaki Masao - - 2009
Alpha-lipoic acid has been shown to possess cancer-cell-killing activity via activation of the apoptosis pathway. In this study, the cytotoxic activities of alpha-lipoic and dihydro-alpha-lipoic acid were compared in HL-60 cells. The cell-killing activity of dihydro-alpha-lipoic acid was higher than that of alpha-lipoic acid. Both alpha-lipoic and dihydro-alpha-lipoic acid induced ...
Vallianou Natalia - - 2009
Diabetic neuropathy presents a major public health problem. It is defined by the symptoms and signs of peripheral nerve dysfunction in diabetic patients, in whom other causes of neuropathy have been excluded. Pathogenetic mechanisms that have been implicated in diabetic neuropathy are: a) increased flux through the polyol pathway, leading ...
Brückner Hans - - 2009
Fourty-nine species and strains of filamentous fungi of the genera Acremonium, Bionectria, Clonostachys, Emericellopsis, Hypocrea/Trichoderma, Lecythophora, Monocillium, Nectriopsis, Niesslia, Tolypocladium, and Wardomyces, deposited with the culture collection of the Centraalbureau voor Schimmelcultures (CBS) in Utrecht, The Netherlands, were grown on nutrient agar plates. Organic extracts of mycelia were analyzed after ...
Narendra N - - 2009
We report a one pot synthesis of Fmoc amino acid derived 4-amino-thiazole derivatives and thiazole linked N-orthogonally protected dipeptidomimetics by the condensation of N(alpha)-Fmoc alpha-halomethylketones with thiourea and Boc/Z-alpha-amino acid thioamides via modified Hantzch protocol. Side chain modified Fmoc amino acids containing 4-amino thiazole moiety have also been synthesized following ...
Günther Svenja - - 2009
Lipoic acid (LA) is a dithiol-containing cofactor that is essential for the function of alpha-keto acid dehydrogenase complexes. LA acts as a reversible acyl group acceptor and 'swinging arm' during acyl-coenzyme A formation. The cofactor is post-translationally attached to the acyl-transferase subunits of the multienzyme complexes through the action of ...
DeFilippis Andrew P AP The Johns Hopkins Ciccarone Center for the Prevention of Heart Disease, Johns Hopkins University, 600 North Wolf Street, Baltimore, MD 21287, USA. - - 2009
We previously reported a >50% increase in mean plasma eicosapentaenoic acid levels in a general medicine clinic population after supplementation with alpha-linolenic acid. In the current analysis, we evaluate the variability of changes in eicosapentaenoic acid levels among individuals supplemented with alpha-linolenic acid and evaluated the impact of baseline plasma ...
Tanaka Hiroshi - - 2008
An efficient synthesis of alpha(2,9) trisialic acid has been achieved via one-pot glycosylation and polymer-assisted deprotection. The synthesis involves chemo- and regioselective alpha-sialylation of ethylthiosialoside with the S-benzoxazolyl (S-Box) sialyl donor. Use of a prelinker to link an activated ester and a vinyl ether via a carbon chain enables polymer-assisted ...
Zembron-Lacny A - - 2009
The aim of this study was to follow up whether the modification of pro-antioxidant status by oral thiol administration such as N-acetylcysteine and alpha-lipoic acid affects the hematological response. Twenty-eight healthy men participated in two independent experiments. Subjects were randomly assigned to one of four groups: controls (C(NAC) and C(ALA)), ...
Sado-Kamdem Sylvain L - - 2009
The antimicrobial activity of alpha-linolenic, capric and lauric acids on Staphylococcus aureus was studied in relation to their effect on the de novo fatty acid biosynthesis. Labelled acetate was used as integrated carbon source and traced in the de novo fatty acid by using a GC-Mass spectrometer and the single ...
Uchigata Yasuko - - 2009
Although insulin autoimmune syndrome (IAS) was found to be strongly related with methimazole, rapidly increasing numbers of cases with alpha lipoic acid-induced IAS have been confirmed to be reported since 2003. As alpha lipoic acid has gained popularity as a supplement for dieting and anti-aging, a warning should be issued.
Taber Douglass F - - 2008
A strategy for the facile alpha-amination of carboxylic acid menthyl esters is described. The resulting diastereomers, readily separable, can be individually carried on to each enantiomer of the FMOC alpha-amino acid. A variety of unnatural side chains were compatible with this approach. The menthyl ester was easily removed from the ...
< 1 2 3 4 5 6 7 8 9 10 11 >