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Results 451 - 500 of 1667
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B?chele Berthold - - 2005
A rapid, sensitive and selective HPLC separation with photodiode array detection was developed for the analysis of the novel pentacyclic triterpenoid acetyl-11-keto-alpha-boswellic acid. Complete baseline separation of acetyl-11-keto-alpha-boswellic acid from the corresponding isomer acetyl-11-keto-beta-boswellic acid was achieved on a fluorinated stationary phase. The standard curve was linear from 0.98 nmol/l ...
Günther S - - 2005
The human malaria parasite Plasmodium falciparum possesses a single mitochondrion and a plastid-like organelle called the apicoplast. Both organelles contain members of the KADH (alpha-keto acid dehydrogenase) complexes--multienzyme complexes that are involved in intermediate metabolism. In the asexual blood stage forms of the parasites, the alpha-ketoglutarate dehydrogenase and branched chain ...
Chen Zhaobin - - 2005
The photophysical properties of N-(alpha-naphthyl)-benzimidazole (alpha-NABI), N-(beta-naphthyl)-benzimidazole (beta-NABI) and N-(alpha-pyridyl)-benzimidazole (alpha-PYBI) were studied and alpha-NYBI exhibit intramolecular charge transfer fluorescence in polar solvents. The fluorescence of benzimidazoles can be quenched by acetic acid and the existence of exciplexes was observed between the benzimidazole derivatives and acetic acid. Particularly, the maximum ...
Roychowdhury Abhijit - - 2005
The unusual amino acid diaminopimelic acid (DAP) was prepared by cross metathesis of appropriately protected vinyl glycine and allyl glycine derivatives. Catalytic hydrogenation of the cross-coupling product resulted in reduction of the double bond and the removal of protecting groups. The resulting compounds were appropriately protected for the polymer-supported and ...
Xu Hong-wu - - 2005
Herein we present a new example of coordination-mediated resolution of racemic acids by a chiral acid. The reaction of copper(II) acetate monohydrate, optically pure O,O'-dibenzoyltartaric acid (DBTA) and racemic alpha-bromo-2-chlorophenylacetic acid (HL1) in acetonitrile solution afforded a binuclear copper(II) complex with D-DBTA dianion, alpha-bromo-2-chlorophenylacetate and acetate as ligands. After decomposition ...
Hodgson David M - - 2005
[reaction; see text] N-Boc syn-7-(2-hydroxyethyl)-4-(alkyl or aryl)sulfonyl-2-azabicyclo[2.2.1]hept-5-enes serve as precursors in syntheses of the neuroexcitants 3-(carboxymethyl)pyrrolidine-2,4-dicarboxylic acid 43, alpha-kainic acid 12, alpha-isokainic acid 14, and alpha-dihydroallokainic acid 77. The key step in these syntheses is the intermolecular radical addition of 2-iodoethanol to a N-Boc 2-(alkyl or aryl)sulfonyl-7-azabicyclo[2.2.1]heptadiene 7 to induce ...
Chruma Jason J - - 2005
The first functional catalytic mimic of the enzyme dialkylglycine decarboxylase is described. This system utilizes a hydrophobically modified polyethylenimine polymer, a pyridoxamine cofactor, and a 2-aryl-2-alkylglycine sacrificial amine source to convert alpha-keto acids to alpha-amino acids at biologically relevant temperatures with multiple turnovers of the pyridoxamine catalyst. The effects of ...
Fast Jonas - - 2005
HAMLET (human alpha-lactalbumin made lethal to tumor cells) is a complex between alpha-lactalbumin and oleic acid that induces apoptosis in tumor cells, but not in healthy cells. Heteronuclear nuclear magnetic resonance (NMR) spectroscopy was used to determine the structure of 13C-oleic acid in HAMLET, and to study the 15N-labeled protein. ...
Pearson Andrew G - - 2005
This work describes our preliminary efforts towards the development of aryl glucuronides as potential probes for heparanase. During the course of these initial investigations, attempted glycosidation of methyl 2,3,4-tri-O-acetyl-alpha-D-glucopyranosyluronate trichloroacetimidate with 4-hydroxycinnamic acid gave a complex mixture of four different components. These were identified as the 1-cinnamyl glucuronate ester 13, ...
Chung Woo Jin - - 2005
[reaction: see text] Catalytic Mannich reactions of 1,1-difluoro-2-trialkyl(aryl)silyl-2-trimethylsilyloxyethenes (3) with a variety of sulfonylimines were utilized for the preparation of alpha,alpha-difluoro-beta-amino acid derivatives (7). The influence of the Lewis acid on the reaction was examined. Methods for the conversion of alpha,alpha-difluoroacylsilanes to alpha,alpha-difluorocarboxylic acids were also explored.
Lin Chang-Ching - - 2005
[reaction: see text] A new method for the synthesis of alpha(2 --> 9) oligosialic acids is developed using phosphite sialyl donors that are protected with a C-5 N-trifluoroacetyl (NHTFA) substituent. Compared with conventional donors, these donors gave a higher degree of alpha-anomeric selectivity during glycosidic bond formation and better yields ...
Villeneuve Masumi - - 2005
Phase diagrams of the Langmuir monolayer of dicyclopropyl alpha mycolic acid (alpha-MA), cyclopropyl methoxy mycolic acid (MeO-MA), and cyclopropyl ketomycolic acids (Keto-MA) from Mycobacterium tuberculosis were obtained by thermodynamic analysis of the surface pressure (pi) vs. average molecular area (A) isotherms at temperatures in the range of 10-46 degrees C. ...
Presto Albert A - - 2005
We report secondary organic aerosol (SOA) yields from the ozonolysis of alpha-pinene under both dark and UV-illuminated conditions. Exposure to UV light reduces SOA yield by 20-40%, with a maximum reduction in yield coinciding with a minimum in the amount of terpene consumed (15-30 ppb). The data are consistent with ...
Hederos Markus - - 2005
[structure: see text] Synthesis of the core tetrasaccharide Manp(alpha1-->6)-Manp(alpha1-->4)-6-(2-aminoethylphosphonic acid)-GlcNp(alpha1-->6)-myo-Ins-1-PO4, found in glycoinositolphospholipids of Trypanosoma cruzi parasites, is described. The key building block, 6-O-(2-azido-3-O-benzyl-6-O-((2-benzyloxycarbonylaminoethyl)phosphonic acid benzyl ester)-2-deoxy-alpha-D-glucopyranosyl)-1-di-O-benzylphosphoryl-4,5-O-isopropylidene-2,3-O-(D-1,7,7-trimethyl[2,2,1]bicyclohept-6-ylidene)-D-myo-inositol, was synthesized using a partially protected glucosyl D-camphorinositolphosphate and a (2-benzyloxycarbonylaminoethyl)phosphonic acid derivative in a regioselective phosphonate esterfication. Elongation with ethyl 2-O-benzoyl-3,4,6-tri-O-benzyl-alpha-D-mannopyranosyl-(1-->6)-2,3,4-tri-O-benzyl-1-alpha-D-thiomannopyranoside using ...
Mellon Christophe - - 2005
Caspase 3 is a cysteinyl protease that mediates apoptotic cell death. Its inhibition may have an important impact in the treatment of several degenerative diseases. The P1 aspartic acid residue is a required element of recognition for this enzyme that was maintained constant along with the adjacent natural valine as ...
Funchal Cláudia - - 2005
In this study we investigate the effects of the branched-chain keto acids (BCKA) alpha-ketoisocaproic (KIC), alpha-ketoisovaleric (KIV), and alpha-keto-beta-methylvaleric (KMV) acids, metabolites accumulating in maple syrup urine disease (MSUD), on the in vitro phosphorylation of glial fibrillary acidic protein (GFAP) and cytoskeletal reorganization in C6-glioma cells. We observed that after ...
Souto E B - - 2005
This study describes the development, preparation and characterization of solid lipid nanoparticles (SLN) containing the novel anti-ageing substance alpha-lipoic acid. Lipoic acid is chemically labile, i.e. the degradation products possess an unpleasant odour. Therefore, the active was encapsulated in SLN. A lipid with low melting point (Softisan 601) was selected ...
Cherry Khalil - - 2005
A general route to alpha-pyrones and 3-substituted isocoumarins from (Z)-iodovinylic acids 1a-f or 2-iodobenzoic acids 4a-c is described, including compounds bearing a substituent on the aromatic ring. Treatment of (Z)-beta-iodovinylic acids 1a-f or 2-iodobenzoic acids 4a-c with various allenyltributyltin reagents in the presence of palladium acetate, triphenylphosphine, and tetrabutylammonium bromide ...
Hanessian Stephen - - 2005
The synthesis of three vicinally substituted azacyclic carboxylic acids in enantiopure form was achieved from a common alpha-amino aldehyde originating from l-leucine. Pyrrolidines and pyrrolidinones were elaborated from alpha,beta-unsaturated gamma-hydroxy-delta-amino acids via azomethine ylide 1,3-dipolar addition and conjugate addition/cyclization strategies, respectively. The azacyclic amino acids were incorporated in a pseudopeptide ...
Jisaka Mitsuo - - 2005
Mouse 8S-lipoxygenase (8-LOX) metabolizes arachidonic acid (AA) specifically to 8S-hydroperoxyeicosatetraenoic acid (8S-HPETE), which will be readily reduced under physiological circumstances to 8S-hydroxyeicosatetraenoic acid (8S-HETE), a natural agonist of peroxisome proliferator-activated receptor alpha (PPAR alpha). Here, we investigated whether 8-LOX could further oxygenate AA and whether the products could activate PPARs. ...
Selvakumar Elangovan - - 2006
The present study investigated the protective efficacy of DL-alpha-lipoic acid on the cyclophosphamide (CP)-induced clastogenicity using the in vivo micronucleus assay. Male Wistar rats of 140 +/- 20 g were categorized into eight groups. Five groups were administered CP (40 mg/kg body weight, intraperitonealy) to induce genotoxicity; four of these ...
Loï Cécile - - 2005
To gain further insight into the ability of ornithine alpha-ketoglutarate (OKG) to generate key metabolites, the aim of this work was to study the short-term metabolism, that is, 1 hour after administration, of OKG in plasma and tissues. Particular attention was paid to keto acids (alpha-ketoglutarate and branched-chain keto acids). ...
Hida Hiroyuki - - 2005
Hydroxycitric acid (HCA) is a major acid component of the tropical plants Garcinia cambogia and Hibiscus subdariffa. (2S,3S)-HCA from G. cambogia was shown to be a potent inhibitor of ATP citrate lyase (EC4.1.3.8), which catalyzes the extramitochondrial cleavage of citrate to oxaloacetate and acetyl-CoA. (2S,3R)-HCA from H. subdariffa inhibits alpha-amylase ...
Ji Jian-Xin - - 2005
The catalytic asymmetric introduction of alkynyl functionality to alpha-amino acid derivatives was realized by the direct addition of terminal alkynes to alpha-imino ester in the presence of chiral Cu(I) complex under mild reaction conditions. Owing to the rich chemistry to which alkyne can be subjected, the present system provides a ...
Mühling J - - 2005
The objective of this study was to determine the dose as well as duration of exposure-dependent effects of L-alanyl-L-glutamine, arginine or taurine on polymorphonuclear neutrophil (PMN) free alpha-keto acid profiles and, in a parallel study, on PMN immune functions. Exogenous L-alanyl-L-glutamine significantly increased PMN alpha-ketoglutarate, pyruvate PMN superoxide anion (O2-) ...
Zhu Ruohua - - 2005
Heavy atom-chelated filter paper was synthesized and used as the substrate for room-temperature phosphorescence (RTP). The synthesis conditions for chelated paper were studied. The Pb-chelated filter paper could selectively induce the RTP of alpha-naphthalene acetic acid (alpha-NAA). The excitation and emission wavelengths of RTP of alpha-NAA were 300 nm and ...
Zeleke Tigabu K - - 2005
This work describes antibodies exhibiting high stereoselectivity and class-specificity towards the enantiomers of free alpha-hydroxy acids. Since the antibodies interact primarily with the carboxyl-hydroxyl-hydrogen triad about the stereogenic center, they are useful for enantiomer analysis of a variety of structurally different alpha-hydroxy acids including aromatic and aliphatic compounds, e.g. lactic ...
Konrad Daniel - - 2005
Alpha-lipoic acid is a naturally occurring cofactor of mitochondrial dehydrogenase complexes and a potent antioxidant. It can interchange between a reduced form and an oxidized form, thereby displaying reducing (antioxidant) and prooxidant properties, respectively. It is suggested that alpha-lipoic acid through its prooxidant properties acutely stimulates the insulin-signaling cascade, thereby ...
Biron Eric - - 2005
N(alpha)-Methylamino acid containing peptides exhibit interesting therapeutic profiles and are increasingly recognized as potentially useful therapeutics. Unfortunately, their synthesis is hampered by the high price and unavaibility of many N(alpha)-methylamino acids. An efficient and practical preparation of N(alpha)-methyl-N(alpha)-(o-nitrobenzenesulfonyl)-alpha-amino acids without extensive purification is described. The procedure is based on the ...
Mohr Justin T - - 2005
The polyhydroxyalkanes 1,6,11,16-hexadecanetetraol (1) and 2,7,12,17-octadecanetetraol (2) were synthesized utilizing the thiophene ring as a scaffold to affix the hydroxyalkyl chains by lithiation of the acidic alpha-hydrogens and subsequent desulfurization. Both compounds exhibited significant anesthetic potency, individually and in additivity studies with hexanol, using immobility in tadpoles as the phenotypic ...
Ferreira Isabel M P L V O - - 2005
The influence of hydrophobic polypeptides concentrated in beer foam, together with the composition of iso-alpha acids and the content of malto-oligosaccharides in beer on foam stability, has been investigated. The objective was to find out whether a shortage of one of these positive contributors to foam stability could be compensated ...
Malowicki Mark G - - 2005
The rate of isomerization of alpha acids to iso-alpha acids (the compounds contributing bitter taste to beer) was determined across a range of temperatures (90-130 degrees C) to characterize the rate at which iso-alpha acids are formed during kettle boiling. Multiple 12 mL stainless steel vessels were utilized to heat ...
Kong Fangming - - 2005
In our search for inhibitors of bacterial fatty acid biosynthesis, two new alpha-pyrones, pseudopyronines A (1) and B (2), were isolated from a marine Pseudomonas sp. F92S91. The naturally occurring alpha-pyrones appeared to be unstable, evidenced by the conversion of pseudopyronine B into an oxidation product, 3-furanone (3). Structural elucidations ...
Bridi Raquel - - 2005
Maple syrup urine disease (MSUD) is an inherited neurometabolic disorder caused by deficiency of branched-chain alpha-keto acid dehydrogenase complex activity which leads to tissue accumulation of the branched-chain alpha-keto acids (BCKAs) alpha-ketoisocaproic acid (KIC), alpha-ketoisovaleric acid (KIV) and alpha-keto-beta-methylvaleric acid (KMV) and their respective amino acids. Neuropathologic findings characteristic of ...
Vasques Vilson de Castro Vde - - 2005
Maple syrup urine disease (MSUD) is an inherited metabolic disease predominantly characterized by neurological dysfunction. Although a variable degree of psychomotor/delay/mental retardation is found in a considerable number of MSUD patients, the mechanisms underlying the neuropathology of this disorder are yet not defined. The present study investigated the effect of ...
Rozhko L F - - 2005
The method for the synthesis of 2-substituted 2-hydroxycarbonylethyl-1-aminoalkylphosphinic acids (I) (pseudo-alpha,alpha-dipeptides) from ammonium and potassium hypophosphites (II) is described. The proposed route to the synthesis of pseudo-alpha,alpha-dipeptides consists in addition hypophosphite to acrylic compounds and formation of the first phosphorus-carbon bond with following addition of aminoacid fragment and formation of ...
Marsh S A - - 2005
Endothelial cell apoptosis contributes to atherosclerosis and may be exacerbated by oxidative stress. Results from clinical trials using antioxidant supplementation are equivocal and could be enhanced by antioxidants with additional non-antioxidant properties such as alpha -lipoic acid and alpha -tocopherol. The aim of this study was to investigate the effects ...
Huang Hsueh-Meei - - 2005
The alpha-ketoglutarate dehydrogenase complex (KGDHC) is a mitochondrial enzyme in the TCA cycle. Inhibition of KGDHC activity by alpha-keto-beta-methyl-n-valeric acid (KMV) is associated with neuron death. However, the effect of KMV in microglia is unclear. Therefore, we investigated the effect of KMV on BV-2 microglial cells exposed to hypoxia or ...
Luppi Elisa - - 2005
An unusual heparin (approximately 1.9 mg/g of dry tissue) was isolated from the marine italian bivalve mollusk Callista chione. Agarose gel electrophoresis showed a high content of the fast-moving heparin component (85 +/- 7.6%) and 15 +/- 1.3% of the slow-moving species. An average molecular mass of 10 950 was ...
Crugeiras Juan - - 2005
We report second-order rate constants of kDO = 120 dm(3) mol(-1) s(-1) and kB = 6.4 x 10(-4) dm(3) mol(-1) s(-1) for exchange for deuterium of the first alpha-methylene proton of the 4-(aminomethyl)pyridine dication in D2O at 25 degree C and I= 1.0 (KCl). These data are consistent with a ...
Terrier François - - 2005
We report on a structural (multinuclear NMR), thermodynamic (pK(a)), and kinetic (Marcus intrinsic reactivity) study of the ionization of benzylic carbon acids activated by an exocyclic (alpha) SO(2)CF(3) group and SO(2)CF(3) or S(O)(=NSO(2)CF(3))CF(3) in the para position of the phenyl ring. The latter exerts an enormous acidifying effect of ca. ...
Kurz Thomas - - 2005
Substituted 3-amino-oxazolidin-2,4-diones have been prepared by reacting cyanohydrins or alpha-hydroxyesters subsequently with 1,1'-carbonyldiimidazole and 1,1-disubstituted hydrazines followed by acidic hydrolysis in case of the intermediate 3-amino-4-imino-oxazolidin-2-ones. Conventional and microwave-assisted syntheses of N',N'-disubstituted alpha-hydroxyhydrazides have been accomplished by reacting substituted 3-amino-oxazolidin-2,4-diones with catalytic amounts of sodium methoxide in methanol.
Mukherjee Sulakshana - - 2005
Use of partial or selective (13)C/(15)N labeling of specific amino acid residues in a given protein to measure the values of (1)J((15)N(i),(13)C(alpha) (i)), (2)J((1)H(N),(13)C(alpha) (i)), (2)J((15)N(i),(13)C(alpha) (i-1)), (1)J((15)N(i),(13)C'(i-1)) and (2)J((1)H(N),(13)C'(i-1)) is described. This was achieved by recording a sensitivity-enhanced 2D [(15)N-(1)H] HSQC experiment, without mixing the spin states of C(alpha) ...
Bradley Richard L - - 2005
OBJECTIVE: To determine whether key appetite-regulating neuropeptides such as melanin-concentrating hormone (MCH), neuropeptide Y (NPY), and alpha-melanocyte-stimulating hormone (alpha-MSH), which are known to mediate energy balance through centrally mediated pathways, also have direct acute effects on the lipolytic activity of murine adipocytes. RESEARCH METHODS AND PROCEDURES: Fully differentiated 3T3-L1 adipocytes ...
Yokoyama Masamoto - - 2005
Interferon-alpha (IFN-alpha) therapy is strongly associated with certain adverse effects, but the pathophysiologic mechanism is unclear. The present study was designed to investigate the influence of peripherally administered IFN- alpha on amino acid levels in the brain. IFN-alpha was administered intraperitoneally (i.p.) once daily to rats, and their brains were ...
Wolski Erika A - - 2005
Binucleate Rhizoctonia (BNR) isolate (232-C6) is an effective biocontrol agent for protection of potato from Rhizoctonia canker, a disease caused by Rhizoctonia solani. Production of hydrolytic enzymes is one of the best known inducible defense responses following microbial infection. We isolated and characterized a cell wall alpha-glucan from BNR, which ...
Wang Yan - - 2005
As a continuation of our SAR studies of dipeptidyl aspartyl-fmk as caspase inhibitors, we explored the replacement of the P2 alpha-amino acid by a peptidomimetic alpha-hydroxy acid. These alpha-carbamoyl-alkylcarbonyl-aspartyl fluoromethylketones were found to be potent caspase inhibitors, and the SAR of these compounds is similar to the corresponding dipeptidyl aspartyl-fmk. ...
Kiryu Takaaki - - 2005
A new alpha-glucuronidase that specifically hydrolyzed O-alpha-D-glucosyluronic acid alpha-D-glucosiduronic acid (trehalose dicarboxylate, TreDC) was purified from a commercial enzyme preparation from Aspergillus niger, and its properties were examined. The enzyme did not degrade O-alpha-D-glucosyluronic acid alpha-D-glucoside, O-alpha-D-glucosyluronic acid beta-D-glucosiduronic acid, O-alpha-D-glucosyluronic acid-(1-->2)-beta-D-fructosiduronic acid, p-nitrophenyl-O-alpha-D-glucosiduronic acid, methyl-O-alpha-D-glucosiduronic acid, or 6-O-alpha-(4-O-alpha-D-glucosyluronic acid)-D-glucosyl-beta-cyclodextrine. ...
Teichert Jens - - 2005
In an open-label, parallel-group study involving 16 patients (8 with severely reduced renal function, 8 with end-stage renal disease needing hemodialysis), the effect of renal function on the pharmacokinetics, metabolism, and safety and of alpha-lipoic acid (thioctic acid) was evaluated by comparing the pharmacokinetic parameters with those of a reference ...
Villas-Boas Maria Helena - - 2005
Ceramide mono (CMH) or dihexoside (CDH) fractions from Trypanosoma cruzi (Dm28c clone) were identified as glucosyl and lactosylceramides containing non-hydroxylated fatty acids. The di-glycosylated form was much more efficiently recognized by sera from T. cruzi-immunized rabbits, indicating that glycosylation influences antigenicity. Fatty acid hydroxylation was also a determinant of serological ...
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