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Results 351 - 400 of 1703
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Bertolasi Valerio - - 2005
The crystal structures of six new crystals of oxo-cholic acids (oxo-CA) are reported: (I) 3alpha,12alpha-dihydroxy-7-oxo-5beta-cholan-24-oic acid; (II) 3alpha,7alpha-dihydroxy-12-oxo-5beta-cholan-24-oic acid; (III) 7alpha-hydroxy-3,12-dioxo-5beta-cholan-24-oic acid; (IV-alpha) and (IV-beta) 12alpha-hydroxy-3,7-dioxo-5beta-cholan-24-oic acid; (V) 3,7,12-trihydroxy-5beta-cholan-24-oic acid. (IV-beta) is a pseudopolymorphic solvated form of (IV-alpha) and contains small channels which can trap disordered water molecules. In all ...
Couch Robin D - - 2005
CDDO, a semi-synthetic triterpenoid derived from oleanolic acid, has the potential to be used as a chemopreventive and chemotherapeutic agent. The structure of CDDO contains two alpha,beta-unsaturated carbonyl moieties, suggesting a mechanism of action involving a conjugate nucleophilic addition. Spectroscopic evaluation with thiol nucleophiles illustrates that an addition does indeed ...
Fuller Amelia A - - 2005
beta-Amino acids are important synthetic targets due to their presence in a wide variety of natural products, pharmaceutical agents, and mimics of protein structural motifs. While beta-amino acids containing geminal substitution patterns have enormous potential for application in these contexts, synthetic challenges to the stereoselective preparation of this class of ...
Miller Crystal M - - 2005
beta-Hematin is an important heme metabolite of malarial infection. Its role as an agent mediating the formation of the reactive electrophile 4-hydroxynonenal (HNE) from polyunsaturated fatty acids was investigated. In vitro formation of HNE was found to be facilitated by the presence of hemozoin in a concentration-dependent fashion. The reactivity ...
Zhang Zhizhen - - 2005
From the root and stem bark of Cephalanthus occidentalis L., a common American wetland species, six new triterpenoid saponins (1 - 6), together with 29 known compounds were isolated and identified. On the basis of spectroscopic analysis and chemical degradation, the structures of new compounds were elucidated as 3-O-beta-glucopyranosylcincholic acid ...
Kapferer Tobias - - 2005
Both enantiomers of the gamma-chiral alpha,beta-dimethylated butyrolactones nat-1 and nat-2 from the moss Plagiomnium undulatum were synthesized stereoselectively through butenolides and tetronic acids, respectively. The configuration of the natural products was determined by GLC comparisons with mono(3-O-acetyl-6-O-tert-butyldimethylsilyl-2-O-methyl)hexakis(6-O-tert-butyldimethylsilyl-2,3-di-O-methyl)-beta-cyclodextrin as a stationary phase.
Braune Annett - - 2005
The degradation of neohesperidin dihydrochalcone by human intestinal microbiota was studied in vitro. Human fecal slurries converted neohesperidin dihydrochalcone anoxically to 3-(3-hydroxy-4-methoxyphenyl)propionic acid or 3-(3,4-dihydroxyphenyl)propionic acid. Two transient intermediates were identified as hesperetin dihydrochalcone 4'-beta-d-glucoside and hesperetin dihydrochalcone. These metabolites suggest that neohesperidin dihydrochalcone is first deglycosylated to hesperetin dihydrochalcone ...
Kiec-Swierczynska Marta - - 2005
Dermatological examinations were performed in 81 workers involved in the manufacture of electric coils for television displays, who had worked for 4 years in contact with a glue containing isobornyl acrylate, acrylic acid, N,N dimethyleneacrylamide, phosphine oxide, bis(2,6-dimethoxybenzoyl) (2,4,4-trimethylpentyl)- and beta-carboxyethyl acrylate. The glue was cured by 350-500-nm ultraviolet and ...
Yamaguchi Masanori - - 2005
Synthesis and antigenic reactivity of 6-O-sulfo sialylparagloboside (SPG) and sialyl Lewis X (sLeX) neo-glycolipids containing lactamized neuraminic acid are described. The suitably protected GlcNAc-beta (1-->3)-Gal-beta (1-->4)-GlcOSE derivative was glycosylated with NeuTFAc-alpha (2-->3)-Gal imidate to give NeuTFAc-alpha (2-->3)-Galbeta (1-->4)-GlcNAc-beta (1-->3)-Gal-beta (1-->4)-GlcOSE pentasaccharide. The partial N,O-deacylation in the NeuTFAc-alpha (2-->3)-Gal part afforded ...
Moon Hyung-In - - 2005
Bioassay-guided fractionation has led to the isolation of two triterpenoid saponins 3-O-[O-beta-D-glucopyranosyl-(1 --> 3)-O-beta-D-glucopyranosyl] oleanolic acid (1), and 3-O-[O-beta-D-glucopyranosyl-(1 --> 2)-O-beta-D-glucopyranosyl] oleanolic acid (2) from the whole plants of Viola ibukiana Makino. Compound 2 showed matrix metalloproteinase-1 expression inhibition activities in a dose-dependent manner.
Dunlop David S - - 2005
The effects of various amino acids on the activity of serine racemase, purified from mouse brain, were examined. Those acting as inhibitors included compounds with electron withdrawing groups on the beta-carbon of alanine (beta-halo-alanines and L-serine-O-sulfate), which can act as enzyme-activated inhibitors, and compounds containing beta-SH groups (cysteine and homocysteine) ...
Wu Yikang - - 2005
[small beta]-Hydroxy acids were readily converted into [small beta]-tosyloxy acids (hydroxyl group activation) in moderate to excellent yields via the O,O-dianions generated by treatment with methyllithium and thus make it possible to prepare anti[small alpha],[small beta]-disubstituted [small beta]-lactones directly from the syn aldols.
Atta-ur-Rahman - - 2005
Phytochemical investigation of the stem bark extract of Boswellia papyrifera afforded two new stilbene glycosides, trans-4',5-dihydroxy-3-methoxystilbene-5-O-{alpha-L-rhamnopyranosyl-(1-->2)-[alpha-L-rhamnopyranosyl-(1-->6)]-beta-D-glucopyranoside (1), trans-4',5-dihydroxy-3-methoxystilbene-5-O-[alpha-L-rhamnopyranosyl-(1-->6)]-beta-D-glucopyranoside (2), and a new triterpene, 3alpha-acetoxy-27-hydroxylup-20(29)-en-24-oic acid (3), along with five known compounds, 11-keto-beta-boswellic acid (4), beta-elemonic acid (7), 3alpha-acetoxy-11-keto-beta-boswellic acid (8), beta-boswellic acid (9), and beta-sitosterol (10). The stilbene glycosides exhibited ...
Tanaka Hiroshi - - 2005
We describe an efficient synthesis of 2,6- and 2,3-sialyl T antigens linked to serine in a one-pot glycosylation. We first investigated the glycosidation of thiosialosides by varying the N-protecting group. Modification of the C-5 amino group of beta-thiosialosides into the N-9-fluorenylmethoxycarbonyl, N-2,2,2-trichloroethoxycarbonyl (N-Troc), and N-trichloroacetyl derivatives enhanced the reactivity of ...
Ma Jianyi - - 2005
In this work, five organotins and pyrethroids pesticides were tested to examine their effects on the three cyanobacteria Anabaena flos-aquae, Microcystis flos-aquae, Mirocystis aeruginosa and on the five green algae Selenastrum capricornutun, Scenedesmus quadricauda, Scenedesmus obliqnus, Chlorella vulgaris, Chlorella pyrenoidosa through 96 h acute toxicity tests. The results indicated that: ...
Yu Jianxin - - 2005
1,2:4,5-Di-O-isopropylidene-3-C-(5-phenyl-1,2,4-oxadiazol-3-yl)-beta-D-psicopyranose 14 was synthesized stereoselectively from 1,2:4,5-di-O-isopropylidene-3-C-amidoximino-3-O-benzoyl-beta-D-psicopyranose 8 using a novel procedure. Treatment of 8 with acetic anhydride, chloroacetyl chloride, propanic anhydride, or benzoyl chloride causes the 3-O-benzoyl group to undergo an intramolecular replacement reaction with neighboring group participation and transfer resulting in a more stable conjugation system of the ...
Shih Mu-Chin - - 2005
Hemoglobin (Hb) variants caused by an elongation of the beta-globin chain are rare. In this study, we present the first case of Hb Tak in a Taiwanese. Hb Tak is caused by an insertion of the dinucleotides AC into codon 146 that abolishes the normal stop codon at position 147. ...
Hlebowicz E - - 2005
During the manufacture of a proprietary peptide drug substance a new impurity appeared unexpectedly. Investigation of its chemical structure established the impurity as a beta-Ala insertion mutant of the mother peptide. The source of the beta-Ala was identified as contamination of the Fmoc-Ala-OH raw material with Fmoc-beta-Ala-Ala-OH. Further studies also ...
Palkó Márta - - 2005
This review is intended to give a short summary of the developments in the field of natural and synthetic alicyclic and heterocyclic hydroxylated beta-amino acids and to focus on the main strategies that have been reported for their synthesis. Given the medicinal and biological significance of the hydroxylated beta-amino acids, ...
Mazurkiewicz Roman - - 2005
The diagnostic values of the following three spectral criteria for the configuration of N-acyl-alpha,beta-dehydro-alpha-amino acid esters were examined: (i) the proton at the beta-position at the double bond of a Z-isomer is shielded if compared with the respective E-isomer (delta(beta)Z < delta(beta)E); (ii) the proton at the nitrogen atom is ...
Reggi Serena - - 2005
Gaucher disease, the most common genetic lysosomal disorder, is caused by the lack of functional acid beta-glucosidase (GCase) and is currently treated at a very high cost by enzyme replacement therapy. In an attempt to provide a safe and cost-effective production system, human placental GCase was produced and purified from ...
León Guillermo - - 2005
Early adverse reactions occur in a number of patients treated with heterologous antivenoms and have been associated with anticomplementary activity (ACA). In order to reduce the ACA of equine whole IgG antivenoms produced by caprylic acid fractionation, three different fractionation protocols were compared: (a) routine caprylic acid fractionation; (b) caprylic ...
Corona-Avendaño S - - 2005
In this work, the results are presented concerning the influence of time on the spectral behaviour of adrenaline (C(9)H(13)NO(3)) (AD) and of the determination of its acidity constants by means of spectrophotometry titrations and point-by-point analysis, using for the latter freshly prepared samples for each analysis at every single pH. ...
Hou H J - - 2004
Four storage conditions including adverse conditions [84% relative humidity (RH), 30 degrees C], mild conditions (57% RH, 20 degrees C), cold conditions (4 degrees C), and uncontrolled ambient conditions were used for storing soybeans. The storage time was 9 months for the adverse conditions and 18 months for the other ...
Matsui Sachiko - - 2004
Glycyrrhizin (GL) is known to have various immunomodulating activities and has long been used clinically as an anti-allergic and anti-hepatitis agent. While the potency of GL against lung inflammatory diseases has been expected, the effect of GL on the lung has been poorly understood. Lung fibroblasts are known as a ...
Krishnaveni N Srilakshmi - - 2005
An environmentally benign and highly efficient supramolecular Michael addition of thiols from the secondary side of beta-cyclodextrin to alpha,beta-unsaturated compounds at the primary side in water is described in quantitative yields; products of undesirable side reactions resulting from polymerization are not observed; the use of cyclodextrin precludes the use of ...
Giordano Cesare - - 2004
A series of new beta-peptido sulfonamides, related to the chemotactic tripeptide fMLF-OMe, has been synthesized. The examined 1a,b-7a,b models contain the achiral -HN-(CH(2))(2)-SO(2)- taurine (Tau) residue or the chiral -HN-CH(nBu)-CH(2)-SO(2)- and -HN-CH(iBu)-CH(2)-SO(2)- residues, corresponding to the beta-aminocarboxylic acid counterparts beta(3)-HNle and beta(3)-HLeu, respectively. The biological activity of the new analogues ...
Sugeac Elena - - 2004
Selected for their expected ability to inhibit HIV replication, a series of eight heterodimers containing a Nucleoside Reverse Transcriptase Inhibitor (NRTI) and an Integrase Inhibitor (INI), bound by a linker, were designed and synthesized. For the NRTIs, d4U, d2U and d4T were chosen. For the INIs, 4-[1-(4-fluorobenzyl)-1H-pyrrol-2-yl]-2,4-dioxobutyric acid (6) and ...
Roach Timothy A - - 2004
Bis[2-(4-phosphonooxyphenoxy)carbonylethyl]phosphinc acid (BPPCEP) was prepared and evaluated as a site-directed affinity reagent for cross-linking human hemoglobin. It was synthesized in four steps starting from 4-benzyloxyphenol and was converted to its pentasodium salt so as to afford efficient cross-linking in an aqueous medium. The reagent was found to specifically cross-link human ...
Chan Katherine Watt - - 2004
Lysosomal acid beta-glucocerebrosidase hydrolyzes glucocerebroside to glucose ceramide. Patients diagnosed with Gaucher disease, however, lack this enzyme, leading to the accumulation of glucocerebroside in tissue macrophages within multiple organs. Such patients can receive enzyme replacement therapy during which a human placental-derived or recombinant form of acid beta-glucocerebrosidase is targeted to ...
Ruberto Giuseppe - - 2004
The investigation of the lipid extract of leaves of Feijoa sellowiana cultivated along the east coast of Sicily has yielded in addition to the widespread secondary metabolites: alpha-tocopherol, flavone, stigmasterol and beta-carotene, an inseparable mixture of tyrosol esters of lignoceric (1a), cerotic (1b) and montanic (1c) acids, and a novel ...
Yang Dan - - 2004
A series of chiral beta(3)-aminoxy acids or amides with various side chains have been synthesized via two different approaches. One is the Arndt-Eistert homologation approach, using chiral alpha-aminoxy acids as starting materials. The other approach, utilizing the enantioselective reduction of beta-keto esters catalyzed by baker's yeast or chiral Ru(II) complexes, ...
Kise Naoki - - 2004
The electroreduction of aromatic beta- and gamma-imino esters prepared from beta-alanine and GABA in the presence of chlorotrimethylsilane and subsequent N-alkoxycarbonylation of the resulting five- and six-membered cyclized amines gave mixed ketals of N-alkoxycarbonyl-2-arylpyrrolidin-3-ones and 2-arylpiperidin-3-ones, respectively. The best result of the electroreductive intramolecular coupling was achieved using Bu(4)NClO(4) as ...
Szeto Hazel H - - 2005
Fluorescent labels are commonly used to investigate the mechanisms of cellular uptake and intracellular distribution of cell-penetrating peptides. However, labels such as fluorescein and rhodamine are relatively large and very lipophilic and may significantly alter physicochemical properties of small peptides. To minimize the impact of the fluorescent probe on a ...
Yasui T - - 2004
The distribution and selectivity of complex carbohydrates in the eccrine glands of the digital pads in the North American raccoon (Procyon lotor) were studied using light and electron microscopic histochemical methods, particularly lectin histochemistry. In the eccrine glands, the dark cells exhibited neutral and acidic glycoconjugates with different saccharide residues ...
He Bin - - 2004
A novel functionalized biodegradable poly(L-lactide-co-beta-benzyl malolactonate) (p-PLMA) with high molecular weight was synthesized through ring-opening copolymerization. Three p-PLMA copolymers with different beta-benzyl malolactonate content were synthesized. The molecular weight (M(w)) and tensile strength of the copolymer with 4 mol% beta-benzyl malolactonate content were 179,800 and 19.0MPa respectively, the molecular weight ...
Kim Jeong H - - 2004
Thermobifida fusca grows well on cellulose and xylan, and produces a number of cellulases and xylanases. The gene encoding a previously unstudied endoxylanase, xyl10B, was overexpressed in E. coli, and the protein was purified and characterized. Mature Xyl10B is a 43-kDa glycohydrolase with a short basic domain at the C-terminus. ...
Hujer Andrea M - - 2004
Knowledge of the amino acids that define recognition of anti-beta-lactamase antibodies is critical to the interpretation of sensitivity and specificity of these antibodies when they are used in a clinical or research setting. To this end, we mapped the epitopes of the CMY-2 and SHV-1 beta-lactamases by using the SPOT ...
Ege Markus - - 2004
[reaction: see text] A new method for the synthesis of beta-amino acids based on 2,3-dihydropyridones as starting materials is presented. Conversions of 2,3-dihydropyridones with NaIO4 and subsequently with base gave the corresponding beta-amino acids in a one-pot procedure. The reactions have been monitored by 1H NMR indicating that the beta-amino ...
Brombacher Horst - - 2004
The alkoxides TpPh,MeZn-OR (R = Me, Et, i-Pr) undergo acid-base reactions with all hydrogen compounds whose acidity is higher than that of the corresponding alcohol ROH. Thus, anion exchange occurs with the common acids acetic acid, acetohydroxamic acid, acetylacetone, phenol, and ethylmercaptan. Alkoxide exchange is observed using methanol, ethanol, and ...
Györgydeák Zoltán - - 2004
2,3,4,6-Tetra-O-acetyl-beta-D-glucopyranosyl- and 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-beta-D-glucopyranosyl azides were transformed into the corresponding per-O-acetylated N-(beta-D-glycopyranosyl) amides via a PMe(3) mediated Staudinger protocol (generation of N-(beta-D-glycopyranosyl)imino-trimethylphosphoranes followed by acylation with carboxylic acids, acid chlorides or anhydrides). The deprotected compounds obtained by Zemplén deacetylation were evaluated as inhibitors of rabbit muscle glycogen phosphorylase b. The best ...
Schmidt Carsten K - - 2004
Aminopolycarboxylic acids, such as ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), diethylenetriaminepentaacetic acid (DTPA), 1,3-propylenediaminetetraacetic acid (1,3-PDTA), beta-alaninediacetic acid (beta-ADA), and methylglycinediacetic acid (MGDA), are used in large quantities in a broad range of industrial applications and domestic products in order to solubilize or inactivate various metal ions by complex formation. ...
Marin Antoine - - 2004
An approach to automatic prediction of the amino acid type from NMR chemical shift values of its nuclei is presented here, in the frame of a model to calculate the probability of an amino acid type given the set of chemical shifts. The method relies on systematic use of all ...
Puk Oliver - - 2004
The role of the putative P450 monooxygenase OxyD and the chlorination time point in the biosynthesis of the glycopeptide antibiotic balhimycin produced by Amycolatopsis balhimycina were analyzed. The oxyD gene is located directly downstream of the bhp (perhydrolase) and bpsD (nonribosomal peptide synthetase D) genes, which are involved in the ...
Mizushina Yoshiyuki - - 2004
We reported previously that lithocholic acid (LCA, 3-alpha-hydroxy-5-beta-cholan-24-oic acid), one of the major compounds in the secondary bile acids, selectively inhibited the activity of mammalian DNA polymerase beta (pol beta) [Mizushina, Y., Ohkubo, T., Sugawara, F., and Sakaguchi, K. (2000) Biochemistry 39, 12606-12613]. The purpose of this study was to ...
Khasanov Alisher B - - 2004
We describe a novel asymmetric approach using Staudinger chemistry to proline-derived spiro-beta-lactams. A chiral group at C-4 of the acid chloride of proline directs the stereoselectivity of Staudinger chemistry and later is sacrificed to obtain optically active 5.4-spiro-beta-lactams. The scope, limitations, and mechanistic rationale for the observed results of Staudinger ...
Tromp Reynier A - - 2004
The use of platinum drugs in antitumour therapy is well established. An important drawback of these chemotherapeutics is the lack of selectivity for tumour cells, usually resulting in severe toxic side effects. A glucuronyl-platinum conjugate was designed and synthesised to test the compatibility of platinum compounds with beta-glucuronidase-based prodrug therapy. ...
Wolin Ronald L - - 2004
Several beta- and gamma-amino acid derivatives were prepared as glycine transport inhibitors and their ability to block the uptake of [(14)C]-glycine in COS7 cells transfected with human glycine transporter-2 (hGlyT-2) were evaluated. A range of lipophilic side chains were tolerated in the beta-amino acid series (i.e., Ph, CH(2)Ph, CH(CH(3))(2), and ...
Buzzoni Valentina - - 2004
With the aim of improving the ability of non-beta-lactam inhibitors to inhibit AmpC-beta-lactamase, a series of 3-aza-phenyl-boronic acid derivatives was obtained using in parallel synthesis. The molecules were tested against Escherichia coli AmpC-beta-lactamase. The best inhibitors, 3-(2-hydroxy-naphthalen-1-ylazo)-phenyl-boronic acid (12) and 3-(2,4-dihydroxy-naphthalen-1-ylazo)-phenyl-boronic acid (14), showed apparent inhibition constant values (K(i)) of ...
Iványi Róbert - - 2004
A family of single-isomer amino-beta-cyclodextrin (amino-beta-CD) derivatives containing an amino or (hydroxy)alkylamino group in one of the primary positions has been synthesized. The steric effect and hydrogen bond forming ability of the different substituents on enantioseparation of acidic enantiomers has been studied by capillary electrophoresis (CE). Three enantiomeric model compounds ...
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