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Acetylated Derivatives (acetylated + derivative)
Selected AbstractsFirst report of non-coloured flavonoids in Echium plantagineum bee pollen: differentiation of isomers by liquid chromatography/ion trap mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 6 2010Federico Ferreres Apicultural products have been widely used in diet complements as well as in phytotherapy. Bee pollen from Echium plantagineum was analysed by high-performance liquid chromatography/photodiode-array detection coupled to ion trap mass spectrometry (HPLC-PAD-MSn) with an electrospray ionisation interface. The structures have been determined by the study of the ion mass fragmentation, which characterises the interglycosidic linkage in glycosylated flavonoids and differentiates positional isomers. Twelve non-coloured flavonoids were characterised, being kaempferol-3- O -neohesperidoside the major compound, besides others in trace amounts. These include quercetin, kaempferol and isorhamnetin glycosides, with several of them being isomers. Acetylated derivatives are also described. This is the first time that non-coloured flavonoids are reported from this pollen, with MS fragmentation proving to be most useful in the elucidation of isomeric structures. Copyright © 2010 John Wiley & Sons, Ltd. [source] Role of acetylation and charge in antimicrobial peptides based on human ,-defensin-3APMIS, Issue 7 2009EMILIOS ANDREW PAPANASTASIOU Cationic antimicrobial peptides are an evolutionarily ancient and essential element of innate immunity in higher organisms. The precise mechanism by which these peptides exert their antimicrobial activity on bacteria is not well understood. Decapeptides based on the C-terminus of human ,-defensin-3 were designed and evaluated to study the role of charge in defining the antimicrobial activity and selectivity of these peptides against Escherichia coli. Acetylated derivatives of these peptides were prepared in order to further evaluate how positively charged primary amines contribute to potency in these small antimicrobial peptides. These peptides enabled us to explore the relationship between net charge, charge distribution and antimicrobial activity. While the results indicate that net charge is a major factor in antimicrobial activity in these peptides, the actual relationship between charge and potency appears to be more complex. [source] Study of Antimalarial Activity of Chemical Constituents from Diospyros quaesitaCHEMISTRY & BIODIVERSITY, Issue 11 2008Cui-Ying Ma Abstract Bioassay-directed fractionation led to the isolation of seven compounds from a sample of the dried leaves, twigs, and branches of Diospyros quaesitaThw. (Ebenaceae). One of the isolates, betulinic acid 3-caffeate (1), showed in vitro antimalarial activity against Plasmodium falciparum clones D6 (chloroquine-sensitive) and W2 (chloroquine-resistant) with IC50 values of 1.40 and 0.98,,M, respectively. Evaluation of compound 1 in the human oral epidermoid (KB) cancer cell line revealed cytotoxicity at ED50 of 4.0,,M. In an attempt to reduce the cytotoxicity of 1, the acetylated derivative 1a and betulinic acid (1b) were prepared. Of the seven isolates, diospyrosin (2) was determined to be a new neolignan. In addition to 1, other known compounds isolated in this study were pinoresinol, lariciresinol, N -benzoyl- L -phenylalaninol, scopoletin, and poriferast-5-en-3,,7, -diol. The structure of 2 was elucidated based on spectroscopic data analysis including 1D- and 2D-NMR, and HR-ESI-MS. [source] Moisture barrier and physical properties of acetylated derivatives with increasing acetylation degreeEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 5 2009Claire Bourlieu Abstract Four acetostearin products with increasing acetylation degree were synthesized by chemical interesterification followed by fractionation/blending stages. Their physical properties and functional barrier properties were studied and compared to the properties of technical tristearin. Increasing acetylation degree (AD) modified the triacylglycerols crystal habits and probably led to an increase in acyl chain fluidity, which induced, at macroscopic levels, a decrease in solid fat content (SFC), in melting point, in surface and bulk material hydrophobicity, and an increased moisture effective diffusivity. Water vapor permeability (WVP) coefficients of the materials were partially influenced by the AD factor, but also by the development of macroscopic cracks in lipids presenting high SFC. Acetylated stearin up to 47% (acetyl mol/mol of esterified chain) presented the lowest WVP at 20,°C resulting from an adequate balance between hydrophobicity and mechanical properties of the material. [source] Four New Lignans with a Bicyclo[3.3.1]nonadienemethanol Skeleton from Cunninghamia lanceolataHELVETICA CHIMICA ACTA, Issue 10 2009Ching-Kuo Lee Abstract Four unique bicyclo[3.3.1]nonadienemethanol lignans, designated lanceolatanins A (1), B (2), C (3), and D (4), along with one previously known compound, isolariciresinol (5), were isolated from the MeOH extracts of the heartwood of Cunninghamia lanceolata. Their structures were elucidated by application of various spectroscopic methods, including 1D- and 2D-NMR techniques, to their acetylated derivatives 1a, 2a, 3a, and 4a. Their possible biosynthetic formations are also discussed. [source] Solid substrate bioassay to evaluate impact of Trichoderma on trichothecene mycotoxin production by Fusarium speciesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 3 2008Maciej Busko Abstract BACKGROUND:Fusarium head blight of wheat is a destructive disease in various wheat-growing regions and leads to significant yield losses for farmers and to contamination of cereal grains with mycotoxins, mainly deoxynivalenol and its derivatives. Toxigenic Fusarium species sporulate on cereal crop residues and produce significant inoculum for epidemics. Reduction of mycotoxin production and pathogen sporulation may be influenced by saprophytic fungal antagonists. RESULTS:Trichoderma isolates were examined in dual culture bioassays on rice with two isolates of Fusarium graminearum Schwabe and two isolates of Fusarium culmorum (W.G. Smith) Saccardo, belonging to three different chemotypes. Production of five trichothecene mycotoxins, deoxynivalenol (DON), 3-acetyl-deoxynivalenol (3AcDON), 15-acetyl-deoxynivalenol (15AcDON), nivalenol (NIV) and fusarenone X (FUS), was reduced by over 95%. Two Trichoderma isolates partially reduced the amounts of four metabolites when inoculated on autoclaved cultures of the same four Fusarium isolates. However, in the case of the 15AcDON chemotype of F. culmorum culture the content of DON increased and that of 15AcDON decreased. Isolates of Trichoderma varied in their ability to inhibit production of the five trichothecene mycotoxins by Fusarium. Susceptibility of the four Fusarium isolates to antagonistic activity of the same Trichoderma isolate differed significantly. CONCLUSION: Selected non-toxigenic Trichoderma isolates proved to be useful biocontrol agents against toxigenic Fusarium pathogens of wheat, significantly reducing production of the trichothecene mycotoxins DON, NIV and their acetylated derivatives. Copyright © 2007 Society of Chemical Industry [source] Stereo- and Biochemical Profiles of the 5-6- and 6-6-Junction Isomers of , - D -Mannopyranosyl [60]FullerenesCHEMISTRY & BIODIVERSITY, Issue 10 2004Yoshihiro Nishida The 5-6- and 6-6-junction isomers of , - D -mannopyranosyl [60]fullerene were studied by means of circular dichroism (CD), deuterium labeling, 1H-NMR, molecular-dynamics (MD) calculations, and a lectin-binding assay. The CD spectra of the O -acetylated derivatives allowed clear discrimination of the isomers, while the 1H-NMR spectra, with assistance from deuterium labeling and MD calculations, served to disclose the unique conformation and molecular geometry of each acetylated isomer in chloroform solution. The deprotected 5-6- and 6-6-isomers, which gave colloidal suspensions in aqueous mixtures, displayed marked activity in blocking lectin-induced hemagglutination by concanavalin,A. [source] | ||||||||||