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Acid Chains (acid + chain)
Kinds of Acid Chains Selected AbstractsStructure,hepatoprotective activity relationship of 3,4-dihydroxycinnamic acid (caffeic acid) derivativesJOURNAL OF APPLIED TOXICOLOGY, Issue 6 2001V. Pérez-Alvarez Abstract 3,4-Dihydroxycinnamic acid (caffeic acid, CAF) is a natural product containing a catechol group with an ,,,-unsaturated carboxylic acid chain that has shown hepatoprotective properties. The aim of this work was to determine the importance of the 4-hydroxy, 3-hydroxy, 3,4-dihydroxy substituents and the double bond moiety on the hepatic pharmacological effects of the molecule. We compared the ability of the caffeic, 4-hydroxycinnamic, 3-hydroxycinnamic, cinnamic and 3,4-dihydroxyhydrocinnamic (a caffeic acid analogue without the double bond) acids at a dose of 50 mg kg,1, p.o., to reduce the liver damage produced by CCl4 (4 g kg,1, p.o.) intoxication in the rat. Cinnamic acid, the non-hydroxylated analogue, only modestly protected the experimental animals challenged with CCl4, suggesting that hydroxyl groups participate in the pharmacological properties of CAF. The 3,4-dihydroxyhydrocinnamic derivative did not show any significant differences when compared with the CAF effect in this model, suggesting that the double bond does not account for the liver pharmacological properties of CAF. In contrast, the 4-hydroxy substituent seems to be very important for hepatoprotective activity because the 4-hydroxy analogue improved almost every hepatic injury marker altered by CCl4, and in a better way than CAF did. Copyright © 2001 John Wiley & Sons, Ltd. [source] Structural compatibility of novel nucleotide modifications with shortened linkages designed for antigene/antisense therapyJOURNAL OF RAMAN SPECTROSCOPY, Issue 5 2004J. Hanu Abstract The impact of isopolar shortened internucleotide linkage modification on the hybridization properties of potential antisense or antigene oligonucleotides was studied by using a model molecular system consisting of polyuridylic acid (PolyU) and analogs of diadenosine monophosphate with the modified linkage. Raman spectra of mixed aqueous solutions were measured at various temperatures and compositions of the mixtures for four types of modified linkage and natural ApA (3,,5,) as a reference. Analysis of the spectral sets provided amounts of formed complexes and their Raman spectra. It has been found that as in the case of ApA (3,,5,), the studied ApA analogs form with PolyU triplex-like complexes containing a central pseudo-chain of closely arranged adenosine dimers. In the case of S - and R -configured 2,,5, and 3,,5, ApCOH A analogs, respectively, the amounts of complexes formed even exceed the ApA. This hybridization effectiveness is reached, however, by a more feasible prolongation of the pseudo-chain, while the stability constant for the initiation step is significantly lower. Raman spectra of the complexes showed that for both of the above analogs the structural compatibility with the natural nucleic acid chain is decreased, because of the distorted position of one adenine residue. This distortion influences the Watson,Crick hydrogen bonds. The two types of linkages may be suitable just for construction of longer antigene or antisense oligonucleotides with alternating lengthened and shortened linkages. There is, however, a warning of possible decreased binding specificity. Copyright © 2004 John Wiley & Sons, Ltd. [source] Synthesis of Conformationally Constrained Glutamic Acid Homologues and Investigation of Their Pharmacological ProfilesCHEMMEDCHEM, Issue 11 2007Paola Conti Prof. Abstract Homologation of the glutamic acid chain together with conformational constraint is a commonly used strategy to achieve selectivity towards different types of glutamate receptors. We investigated the effects of a further increase in the distance between the amino acid moiety and the distal carboxylate group of model compounds (±)- 1 and (±)- 2 on their activity/selectivity profiles. We therefore synthesized new derivatives (±)- 3,(±)- 6, which are homologues of glutamic acid containing three additional carbon units. Moreover, because the potency of NMDA antagonists can be markedly increased by replacing the distal carboxylate with the bioisosteric phosphonate group, we also prepared the corresponding phosphonate derivatives (±)- 7,(±)- 10. All new compounds were submitted to binding assays with iGluRs, and derivatives (±)- 3,(±)- 6 were also tested in second messenger assays at representative mGluR subtypes. All the applied structural modifications were detrimental to the interaction with NMDA receptors. Conversely, structural variation of the nonselective mGluR ligand (±)- 2 led to derivative (±)- 5, which behaved as a selective group,I metabotropic receptor antagonist. Notably, upon i.c.v. administration in DBA/2 mice, amino acid (±)- 5 produced a significant protection against audiogenic seizures, whereas it was inactive after i.p. administration. [source] The ester-bonded palmitoyl side chains of Pam3CysSerLys4 lipopeptide account for its powerful adjuvanticity to HLA class,I-restricted CD8+ T,lymphocytesEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 7 2003Anca Reschner Abstract Molecularly defined adjuvants are urgently required to implement immunization protocols by which CD8+ T,cells induction is envisaged. We show here that the synthetic lipopeptide Pam3CysSerLys4 (P3CSK4) strongly enhances the expansion of antigen-specific IFN-,+CD8+ cells in vitro. These effects critically depend on the presence of two ester-bonded palmitoylated side chains. In fact, T,cell expansion is impaired in the presence of derivatives bearing two non-palmitoylated fatty acid chains, while derivatives with only one amide-bonded palmitoylated residue are completely inactive and behave like the non-lipidated peptide backbone. P3CSK4 is not mitogenic for T,lymphocytes and can modulte DC immune biological properties. Indeed, doses as low as 100,ng/ml increase CD86, CD83 and CD40 surface expression on DC, fail to induce CCR7, and trigger a defined pattern of soluble factors associated to immune effector functions. In particular, substantial amounts of TNF-,, IL-6, CCL2 and CXCL10, in the absence of IFN-,, IFN-,, IL-15, IL-12p70 and CX3CL1, can be measured. Accordingly, antigen-specific CD8+ T,cells expanded in vitro express CCR2 and CXCR3 chemokine receptors. Altogether our data suggest that human DC are able to respond to chemically different synthetic lipopeptide analogs and that optimal adjuvanticity to CD8+ T,cell induction is achieved by the palmitoylated structures. [source] Chemical Modification of Pigskin Gelatin: Factors Affecting the Esterification of Gelatin with Fatty AcidJOURNAL OF FOOD SCIENCE, Issue 9 2001K.B. Djagny ABSTRACT: This study investigated the esterification of pigskin gelatin with fatty acid catalyzed by acid in aqueous medium. Factors affecting the esterification reaction B temperature, pH, water content, fatty acid concentration, fatty acid type and reaction time- were elucidated in the view of optimizing the reaction. Under the same experimental conditions, increase in fatty acid concentration permitted the determination of the maximum amount of fatty acid that could be esterified per unit weight of gelatin and demonstrated that not all the hydroxyl functional groups present in the gelatin could be blocked by the fatty acid chains. [source] Computer-assisted interpretation of atmospheric pressure chemical ionization mass spectra of triacylglycerolsRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 23 2006Josef Cva Current lipidomics approaches require simple and rapid algorithms enabling the interpretation of mass spectra of lipids. Most lipids are complex mixtures of related components in which the composition of the aliphatic fatty acid chains varies from one molecule to the next. Triacylglycerols (TAGs) are an example of such a lipid class. Fatty acid chains are the only parts of the molecule to change from one species to another. Fatty acids, and consequently also TAGs, can be characterized by two parameters; the number of carbon atoms and the number of double bonds. All calculations reflecting relations among ions in the spectra can be easily made using these parameters. An algorithm for the automated interpretation of TAGs from atmospheric pressure chemical ionization mass spectra (TriglyAPCI) is presented in this paper. The algorithm first identifies diacylglycerol fragments and molecular adducts. In the next step, relations among the ions are searched and possible TAG structures are suggested. Individual features of the algorithm are described in detail and the software performance is demonstrated for the liquid chromatography/mass spectrometric (LC/MS) analysis of TAGs isolated from the termite Prorhinotermes canalifrons. Copyright © 2006 John Wiley & Sons, Ltd. [source] Elucidation of the molecular structure of lipid A isolated from both a rough mutant and a wild strain of Aeromonas salmonicida lipopolysaccharides using electrospray ionization quadrupole time-of-flight tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2005Anas El-Aneed The chemical structure of lipid A, isolated by mild acid hydrolysis from a rough mutant and a wild strain of Aeromonas salmonicida lipopolysaccharide, was investigated using electrospray ionization quadrupole time-of-flight (QqToF) hybrid tandem mass spectrometry and showed a great degree of microheterogeneity. The chemical structure of the main constituent of this heterogeneous mixture was identified as a , -D-(1,,,6) linked D-glucosamine disaccharide substituted by two phosphate groups, one being bound to the non-reducing end at position O-4, and the other to the position O-1 of the reducing end of the D-glucosamine disaccharide. The location of the fatty acids linked to the disaccharide backbone was established by identifying diagnostic ions in the conventional QqToF-MS scan. Low-energy collision tandem mass spectrometry analysis of the selected precursor diagnostic ions confirmed, unambiguously, their proposed molecular structures. We have established that myristyloxylauric (C14:0(3- O(12:0))) acid residues were both N-2, and O-3, linked to the non-reducing end of the D-GlcN residue, and that two 3-hydroxymyristic (C14:0(3-OH)) acid chains acylated the remaining positions of the reducing end. The MS and MS/MS data obtained allowed us to determine the complex molecular structure of lipid A. The QqToF-MS/MS instrument has shown excellent superiority over a conventional quadrupole-hexapole-quadrupole tandem instrument which failed to fragment the selected precursor ion. Copyright © 2005 John Wiley & Sons, Ltd. [source] Screening for disulfide-rich peptides in biological sources by carboxyamidomethylation in combination with differential matrix-assisted laser desorption/ionization time-of-flight mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 17 2001Susanne Neitz Peptides with biological functions often contain disulfide bridges connecting two cysteine residues. In an attempt to screen biological fluids for peptides containing cysteine residues, we have developed a sensitive and specific method to label cysteines selectively and detect the resulting molecular mass shift by differential mass spectrometry. First, reduction of disulfide bridges and carboxyamidomethylation of free thiols is adjusted to quantitatively achieve cysteine alkylation for complex peptide extracts. In a second step, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) before and after chemical derivatization is performed, followed by differential analysis to determine shifted peaks; shifted peaks belong to cysteine-containing peptides, other peaks remain unchanged. The number of cysteines can then be determined by the resulting molecular mass shift. Free, reduced cysteines are shifted by 57,u, two oxidized cysteines involved in disulfide bridges (cystine) result in a shift to higher mass per disulfide bridge of 116,u. Disulfide bridges connecting different amino acid chains like insulin break up during reduction. In this case, two peaks with lower molecular masses result from a single one in the unmodified sample. With this technique, we were able to identify cysteine-containing peptides and short fragments of proteins present in human blood filtrate. Copyright © 2001 John Wiley & Sons, Ltd. [source] An X-ray diffraction study of partially ordered electron density in clathrates of Dianin's compound that include simple carboxylic acidsACTA CRYSTALLOGRAPHICA SECTION B, Issue 1 2003Ronald W. H. Small The nature of the inclusions in ten clathrate complexes of Dianin's compound have been investigated by the use of electron-density difference maps. The guest species are the first eight straight-chain carboxylic acids, formic to octanoic, a branched-chain acid (dimethylacetic acid) and trifluoroacetic acid. The point-group symmetry of the clathrate cavity, , is satisfied by partial occupation of symmetry-related sites by two included molecules in the case of formic, acetic and trifluoroacetic acids and by a single molecule in the remainder. Hydrogen-bonding requirements in the case of formic and acetic acids are satisfied by dimer formation; in the trifluoroacetic acid complex the two acid molecules form hydrogen bonds to framework O atoms at either end of the cavity. The adoption of gauche conformations in heptanoic and octanoic acid chains shortens them sufficiently that they fit the cavity with only slight distortion. [source] | ||||||||||