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31.
Analysis of T-2 and HT-2 toxins in cereal grains by immunoaffinity clean-up and liquid chromatography with fluorescence detection 总被引:8,自引:0,他引:8
Visconti A Lattanzio VM Pascale M Haidukowski M 《Journal of chromatography. A》2005,1075(1-2):151-158
A sensitive, precise and accurate method has been developed for the simultaneous determination of T-2 and HT-2 toxins in cereal grains at ppb levels using high-performance liquid chromatography (HPLC) with fluorescence detection and 1-antroylnitrile (1-AN) as labeling reagent after immunoaffinity clean-up. Cereal samples were extracted with methanol/water (90:10, v/v), and the extracts were cleaned-up through commercially available immunoaffinity columns containing monoclonal anti-T-2 antibodies (T-2 test HPLC, Vicam). T-2 and HT-2 toxins were quantified by reversed-phase HPLC with fluorometric detection (excitation wavelength 381 nm, emission wavelength 470 nm) after derivatization with 1-AN. The monoclonal antibody showed 100% cross-reactivity with both T-2 and HT-2 toxin, and the immunoaffinity column clean-up was effective up to 1.4 microg of both toxins. The method was successfully applied to the analysis of T-2 and HT-2 toxins in wheat, maize and barley. Recoveries from spiked samples with toxin levels from 25 to 500 microg/kg ranged from 70% to 100%, with relative standard deviation generally lower than 8%. The limit of detection of the method was 5 microg/kg for T-2 toxin and 3 microg/kg for HT-2 toxin, based on a signal-to-noise ratio 3:1. HT-2 toxin was detected in ten naturally contaminated wheat samples out of 14 samples analyzed, with toxin levels ranging from 10 to 71 microg/kg; three of them contained also T-2 toxin up to 12 microg/kg. 相似文献
32.
Michelangelo Gruttadauria Francesco Buccheri Silvestre Buscemi Giuseppe Cusmano Renato Noto Giuseppe Werber 《Journal of heterocyclic chemistry》1992,29(1):233-236
The photochemical behaviour of some substituted aldehyde thiosemicarbazones 1a-k has been investigated in methanol at 254 nm. Thiosemicarbazones of glyoxil methyl ester 1a-f cyclized to furnish the 3-thioxo- 1,2,4-triazin-5-one 2 ring system. The remaining thiosemicarbazones 1g-j gave 1,2,4-triazoline 4 derivatives. 相似文献
33.
A high-yielding three-step synthesis of goniothalamin involving an enzymatic kinetic resolution in the presence of vinyl acrylate followed by ring-closing metathesis is discussed. 相似文献
34.
Bedini E De Castro C Erbs G Mangoni L Dow JM Newman MA Parrilli M Unverzagt C 《Journal of the American Chemical Society》2005,127(8):2414-2416
Many phytopathogenic bacteria display lipopolysaccharides (LPS) with the O-chain repeating unit [alpha-l-Rha-(1-->3)-alpha-l-Rha-(1-->3)-alpha-l-Rha-(1-->2)](n)(). This trisaccharide unit was synthesized and oligomerized to obtain hexa- and nonasaccharides. The deprotected rhamnans were effective in suppressing the hypersensitive response (HR) and in inducing PR-1 gene expression in Arabidopsis thaliana. Conformational analysis of the oligorhamnans by NMR spectroscopy and molecular dynamics calculations revealed that a coiled structure develops with increasing chain length of the oligosaccharide. This is associated with increasing efficacy in HR suppression and PR-1 gene expression. We therefore infer that the coiled structure of phytopathogenic bacteria is a plant-recognizable pathogen-associated molecular pattern (PAMP). 相似文献
35.
Sunto A partire da uno spazio topologico X e da un prefascio di gruppi abeliani & su X si determina, sotto npportune ipotesi, e
per ogni dimensione n, un corrispondente fibrato gruppale abeliano tale che il gruppo di omotopia legata alle fibre delle
sue sezioni globali è isomorfo alla coomologia di Čech n-dimensionale a coefficienti in & dello spazio X. 相似文献
36.
Michelangelo?ConfortiEmail author Romeo?Rizzi 《4OR: A Quarterly Journal of Operations Research》2004,2(2):153-159
We review the recent three-volume monograph authored by Alexander Schrijver, Combinatorial Optimization - Polyhedra and Efficiency, Springer-Verlag, 2003, ISBN 3-540-44389-4, 1881 pages (in a slip-case), price: € 89,95 .Received: November 2003, Revised: January 2004, AMS classification:
90C57, 68R10, 05C99 相似文献
37.
Green conditions for the Suzuki reaction using microwave irradiation and a new HNT‐supported ionic liquid‐like phase (HNT‐SILLP) catalyst
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Marina Massaro Serena Riela Giuseppe Lazzara Michelangelo Gruttadauria Stefana Milioto Renato Noto 《应用有机金属化学》2014,28(4):234-238
A new catalytic system based on modified halloysite nanotubes was employed in the Suzuki reaction under microwave irradiation. A set of solvents, times and bases was screened and the best experimental conditions were obtained when the reactions were carried out for 10 min in water–ethanol at 120 °C in presence of K2CO3 as base. Good recyclability was observed. The new catalytic system was employed using either 1 mol% or 0.1 mol%. The palladium catalyst displayed good activity, allowing the synthesis of several biphenyl compounds in high yield working with only 0.1 mol% palladium loading. The application of microwave irradiation decreased the reaction time and also improved conversion with respect to traditional heating. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
38.
A Semisynthetic Approach to New Immunoadjuvant Candidates: Site‐Selective Chemical Manipulation of Escherichia coli Monophosphoryl Lipid A
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Dr. Daniele D'Alonzo Manuela Cipolletti Giulia Tarantino Marcello Ziaco Dr. Giuseppina Pieretti Prof. Alfonso Iadonisi Prof. Giovanni Palumbo Dr. Alberto Alfano Dr. Mariateresa Giuliano Prof. Mario De Rosa Prof. Chiara Schiraldi Dr. Marcella Cammarota Prof. Michelangelo Parrilli Dr. Emiliano Bedini Prof. Maria M. Corsaro 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(31):11053-11063
A semisynthetic approach to novel lipid A derivatives from Escherichia coli (E. coli) lipid A is reported. This methodology stands as an alternative to common approaches based exclusively on either total synthesis or extraction from bacterial sources. It relies upon the purification of the lipid A fraction from fed‐batch fermentation of E. coli, followed by its structural modification through tailored, site‐selective chemical reactions. In particular, modification of the lipid pattern and functionalization of the phosphate group as well as of the sole primary hydroxyl group were accomplished, highlighting the unusual reactivity of the molecule. Preliminary investigations of the immunostimulating activity of the new semisynthetic lipid A derivatives show that some of them stand out as promising, new immunoadjuvant candidates. 相似文献
39.
Renato Noto Paolo Lo Meo Michelangelo Gruttadauria Giuseppe Werber 《Journal of heterocyclic chemistry》1996,33(3):863-872
In order to gain further mechanistical information about the cyclization of thiosemicarbazones and thiosemicarbazone-type substrates induced by metallic salts as oxidizing agents, we performed the synthesis of substrates 1a-s and a kinetic study of the oxidative cyclization of 1 to 5-imino-Δ2-1,3,4-thiadiazole 2 and 1,2,4-triazoline-5-thione 3 derivatives induced by methanolic ferric chloride solutions. The results of cyclization were compared to those of corresponding semicarbazones. The kinetic data were analyzed by means of the Hammett's equation and ρ values discussed. 相似文献
40.
Silipo A Leone MR Erbs G Lanzetta R Parrilli M Chang WS Newman MA Molinaro A 《Angewandte Chemie (International ed. in English)》2011,50(52):12610-12612
Sugar coat: The nitrogen-fixing soil bacterium Bradyrhizobium sp. BTAi1 is coated with a unique lipopolysaccharide that does not induce innate immune responses in its host plant Aeschynomene indica or in different plant families. The chemical nature of the monosaccharide forming the polymer (see picture) is unprecedented in nature, which helps to avoid "harmful" recognition by its symbiotic host. 相似文献