Time filter

Source Type

Szeged, Hungary

Szekeres A.,University of Szeged | Budai A.,Edison House Holding Co. | Bencsik O.,University of Szeged | Nemeth L.,Edison House Holding Co. | And 4 more authors.
Journal of chromatographic science

Fumonisins are a class of mycotoxins produced mainly by Fusarium species, which is primary fungal contaminant of the maize and maize-derived products around the world. The B-series fumonisins (FB1, FB2 and FB3) are the most abundant and toxic constituent; thus, their levels are regulated generally worldwide. In this study, we developed a reliable method for the measurement of fumonisin FB1, FB2 and FB3 mycotoxins from maize samples without the time-consuming derivatization step using a high-performance liquid chromatograph coupled with corona charged aerosol detector. The detection and quantitation limit of the whole method were 0.02 and 0.04 mg/kg for each fumonisins, respectively. The detection linearity was tested in the calibration range of 2 orders of magnitude and the recoveries from the spiked samples were determined. The developed method proved to be sufficient to measure the maximum residue levels of fumonisins, which are specified in European Union and United States in maize and maize-based products. © The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com. Source

Bartok T.,Fumizol Ltd. | Tolgyesi L.,Eotvos Lorand University | Szecsi A.,Hungarian Academy of Sciences | Mesterhazy A.,Cereal Research Non Profit Ltd. | And 3 more authors.
Journal of Chromatographic Science

Five previously unknown fumonisin mycotoxins (iso-FP1, iso-FP2,3a, iso-FP2,3b, FP4 and iso-FP 4) and three previously described FP analogues (FP1-3) were detected in a solid rice culture inoculated with Fusarium verticillioides. The fumonisins were characterized by high-performance liquid chromatography-electrospray ionization time-of-flight mass spectrometry (HPLC-ESI-TOFMS) and ion trap mass spectrometry (ITMS). The FP isomers were separated by using a flat gradient on a special, high-coverage C18, narrow-bore HPLC column (YMC-Pack J'sphere ODS H80), which was suggested for the separation of structural isomers. The verified structures of the FP1-3 mycotoxins, the relative retention times (by HPLC-ESI-TOFMS and ITMS), the exact masses of the molecular ions (by TOFMS) and the masses of the product ions, including the hydrocarbon backbones (by ITMS) of the new compounds, strongly suggested their structures. © 2013 The Author [2013]. Published by Oxford University Press. All rights reserved. Source

Kadar Z.,University of Szeged | Kovacs D.,University of Szeged | Frank E.,University of Szeged | Schneider G.,University of Szeged | And 5 more authors.

A straightforward and reliable method for the regioselective synthesis of steroidal 1,4-disubstituted triazoles and 1,5-disubstituted tetrazoles via copper(I)-catalyzed cycloadditions is reported. Heterocycle moieties were efficiently introduced onto the starting azide compound 3β-acetoxy- 16β-azidomethylandrost-5-en-17β-ol through use of the "click" chemistry approach. The antiproliferative activities of the newly-synthesized triazoles were determined in vitro on three human gynecological cell lines (HeLa, MCF7 and A2780) using the microculture tetrazolium assay. © 2011 by the authors; licensee MDPI, Basel, Switzerland. Source

Bartok T.,University of Szeged | Bartok T.,Fumizol Ltd. | Tolgyesi L.,Eotvos University Joint Research and Training on Separation Techniques | Tolgyesi L.,Kromat Ltd. Co. | And 4 more authors.
Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment

The aim of this study was to apply RP-HPLC/ESI-ITMS and RP-HPLC/ESI-TOFMS to investigate and characterise six new higher molecular weight fumonisins (three pairs of isomers) extracted from a Fusarium verticillioides-infected solid rice culture. The ITMS and ITMS2 spectra clearly indicated the m/z values (960, 984 and 986) of the protonated molecules and the FB1 toxin-like structures of these compounds, respectively. Moreover, the data evaluation software of the TOFMS equipment unambiguously demonstrated the exact masses of the protonated molecules and the suggested empirical formulae (C50H89NO16, C52H89NO16 and C52H91NO16) of the new fumonisins, with mass accuracy in the range between 0.1 and -1.1 ppm. Subtraction of the empirical formula of FB1 toxin (C34H59NO15) from these formulae and correction for the mass of water split-off from the fumonisin molecule during ester formation resulted in the empirical formulae of the fumonisin backbone esterifying agents (fatty acids): C16H32O2 (palmitic acid, PA), C18H32O2 (linoleic acid, LA) and C18H32O2 (oleic acid, OA). We denoted the new compounds as esterified FB1 (EFB1) toxins, with the suggested names EFB1 PA, iso-EFB1 PA, EFB1 LA, iso-EFB1 LA, EFB1 OA and iso-EFB1 OA. The total amount of these new compounds comprised 0.1% of the FB1 concentration, which may be rated as significant when it is considered that these new components are significantly more apolar than earlier-described fumonisins, and their uptake into and toxicity elicited in the various tissues of living organisms may therefore also be significantly different from those of other fumonisins. © 2010 Taylor & Francis. Source

Frank E.,University of Szeged | Kovacs D.,University of Szeged | Schneider G.,University of Szeged | Wolfling J.,University of Szeged | And 3 more authors.
Molecular Diversity

Efficient synthesis of novel 16-spiroisoxazolines in the androst-5-ene series was carried out by 1,3-dipolar cycloadditions of different aryl nitrile oxides to 3β-acetoxy-16-methylene-androst-5-en-17-one. During the intermolecular ring closures, the attack of the O terminus of the nitrile oxide dipole from the α side on C-16 predominated for steric reasons permitting the reactions to occur in a regio- and stereoselective manner. The minor isomers in which the angular methyl group on C-13 and the O atom of the isoxazoline heteroring were in the β, β-cis orientation were obtained in a yield of only ∼10 %. Moreover, the conversions were influenced to a certain extent by the substituents on the aromatic moiety of the 1,3-dipoles. The stereostructures of the related diastereomers were confirmed by 2D NMR methods. Deacetylation of the primarily formed main products resulted in the corresponding 3β-OH analogs, which were further reduced to furnish 3β, 17β-diols. All of the synthetized compounds were subjected to in vitro pharmacological studies in order to investigate their antiproliferative effects on three malignant human adherent cell lines (HeLa, MCF7, and A431). © 2014 Springer International Publishing. Source

Discover hidden collaborations