TY - CONF A1 - Keller, Julia A1 - Haase, H. A1 - Koch, Matthias T1 - Electrochemistry-mass spectrometry (EC-MS) as a versatile tool to simulate the biotransformation of citrinin – A comparative study N2 - Mycotoxins can be found worldwide in foods and feed and cause a variety of mold-related health risks which makes it necessary to further examine their toxic effects and metabolic fate in human and other mammals. Beside standard in vitro and in vivo assays with liver cell preparations or rodents an increasing interest in new simulation methods are playing a growing role. Electrochemistry (EC) is one of these novel techniques and has been used successfully and efficiently in pharmacological and drug research for several years now. The primary objective of this study was to determine the capability of EC as a supportive and versatile instrument to elucidate metabolic pathways of mycotoxins. On the example of the food relevant mycotoxin Citrinin a coulometric flow through cell equipped with a carbon working electrode was used to oxidize Citrinin by applying potential between 0.7 and 2.5 V vs. Pd/H2. The electrochemically generated oxidation products were then analyzed by mass-spectrometric detection coupled online to EC (EC-MS) and compared with data from a standard in vitro model with human and rat liver microsomes preparations. To receive a comprehensive assessment of oxidative techniques chemical oxidation by Fenton´s reaction was performed as well. The obtained LC-MS/MS data confirmed the production of Dihydrocitrinone by all of the three tested oxidation systems and demonstrates the potential of EC-MS for the successful prediction of the main phase I metabolic reactions of mycotoxins, since Dihydrocitrinone is the mainly formed metabolite by humans after intake of Citrinin. Beside the identified Dihydrocitrinone from electrochemical, enzymatic and chemical oxidation of Citrinin there is still a number of yet unknown compounds. As the next step structural characterization of the generated oxidation products by NMR and X-ray analysis will be enabled by their large-scale production using preparative EC cells. T2 - Rapid Methods CY - Amsterdam, The Netherlands DA - 07.11.2016 KW - Electrochemistry KW - Mycotoxin KW - Oxidation PY - 2016 AN - OPUS4-38215 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Borzekowski, Antje A1 - Drewitz, T. A1 - Keller, Julia A1 - Pfeifer, Dietmar A1 - Kunte, Hans-Jörg A1 - Koch, Matthias A1 - Rohn, S. A1 - Maul, R. T1 - Biosynthesis and characterization of zearalenone-14-sulfate, zearalenone-14-glucoside and zearalenone-16-glucoside using common fungal strains N2 - Zearalenone (ZEN) and its phase II sulfate and glucoside metabolites have been detected in food and feed commodities. After consumption, the conjugates can be hydrolyzed by the human intestinal microbiota leading to liberation of ZEN that implies an underestimation of the true ZEN exposure. To include ZEN conjugates in routine analysis, reliable standards are needed, which are currently not available. Thus, the aim of the present study was to develop a facilitated biosynthesis of ZEN-14-sulfate, ZEN-14-glucoside and ZEN-16-glucoside. A metabolite screening was conducted by adding ZEN to liquid fungi cultures of known ZEN conjugating Aspergillus and Rhizopus strains. Cultivation conditions and ZEN incubation time were varied. All media samples were analyzed for metabolite formation by HPLC-MS/MS. In addition, a consecutive biosynthesis was developed by using Fusarium graminearum for ZEN biosynthesis with subsequent conjugation of the toxin by utilizing Aspergillus and Rhizopus species. ZEN-14-sulfate (yield: 49%) is exclusively formed by Aspergillus oryzae. ZEN-14-glucoside (yield: 67%) and ZEN-16-glucoside (yield: 39%) are formed by Rhizopus oryzae and Rhizopus oligosporus, respectively. Purities of ≥73% ZEN-14-sulfate, ≥82% ZEN-14-glucoside and ≥50% ZEN-16-glucoside were obtained by 1H-NMR. In total, under optimized cultivation conditions, fungi can be easily utilized for a targeted and regioselective synthesis of ZEN conjugates. KW - Mycotoxin KW - Zearalenone KW - Conjugate KW - Biosynthesis KW - Fusarium KW - Aspergillus KW - Rhizopus PY - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-444246 SN - 2072-6651 VL - 10 IS - 3 SP - Article 104, 1 EP - 15 PB - MDPI CY - Basel AN - OPUS4-44424 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Keller, Julia A1 - Lörchner, Dominique A1 - Koch, Matthias T1 - Electrochemistry coupled to mass spectrometry (EC/MS) – A valuable tool to simulate metabolic processes of mycotoxins? N2 - Mycotoxins are secondary metabolites produced by fungi contaminating food and feed worldwide. Intake of these foodborne toxins can cause several diseases in humans and animals highlighting the need to understand metabolic pathways of mycotoxins. Methods of choice have been in vitro and in vivo approaches, so far. Beside hundreds of documented mycotoxins numerous new ones need to be elucidated and enhance the demand for fast and reliable methods. Here, we present electrochemistry coupled to mass spectrometry (EC/MS set up Fig. 1) as novel and promising tool in mycotoxin research. Electrochemical oxidation of mycotoxins like zearalenone, citrinin or dihydroergocristine lead to several oxidation products known from phase I biotransformation as well as new interesting reaction products analyzed by EC/MS, LC MS/MS and ESI-HRMS. To ensure a comparative overview results obtained from electrochemical oxidation experiments were compared to Fenton reaction, UV irradiation and microsomal experiments. The presentation will point out the benefits and drawbacks of EC/MS in mycotoxin research on the basis of selected food relevant mycotoxins. T2 - ANAKON CY - Tübingen, Deutschland DA - 03.04.2017 KW - Electrochemistry KW - Mycotoxin KW - Metabolism PY - 2017 AN - OPUS4-39766 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Keller, Julia A1 - Haase, H. A1 - Koch, Matthias T1 - Coupling of electrochemistry with LC/MS for generation and identification of mycotoxin oxidation products N2 - Mycotoxins cause a variety of mold-related health risks which makes it necessary to further examine their metabolic pathways in human and other mammals. Beside standard in vitro assays with liver cell microsomes an increasing interest in new and rapid simulation techniques are playing a growing role in mycotoxin research. Herein, the coupling of electrochemistry with liquid chromatography and mass spectrometry (EC/LC/MS) is presented as fast and simple method to investigate the oxidative fate of mycotoxins. For this case study, two food relevant mycotoxins (zearalenone and citrinin) were selected. Experiments were performed by using an electrochemical flow through cell integrated in the flow path of the autosampler of the chromatographic system. The reaction mixture was separated by a RP-C18 column and analyzed by a single quadrupole MS (Figure 1). Oxidation products were generated by applying potentials of 400, 800, 1200 and 1600 mV vs Pd/H2 using a glassy carbon working electrode. Different oxidation reactions like hydroxylation, dehydrogenation and dimerization lead to a diverse product pattern of the investigated mycotoxins. In a comparative study, electrochemical generated reaction products were compared with metabolites produced by human and rat liver microsomes in vitro. The obtained data show that EC/LC/MS is a versatile and promising tool in mycotoxin research to support metabolic investigations of known and unknown mycotoxins. T2 - Mycotoxin Workshop CY - Bydgoszcz, Poland DA - 19.06.2017 KW - Electrochemistry KW - Mycotoxin KW - LC/MS KW - Oxidation PY - 2017 AN - OPUS4-40779 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Keller, Julia A1 - Hantschke, Luisa A1 - Haase, H. A1 - Koch, Matthias T1 - Synthesis and Structural Identification of a Biaryl Ether-Linked Zearalenone Dimer N2 - A new dimer of the food-relevant mycotoxin zearalenone was isolated after electrochemical and chemical oxidation. The structure was determined as a 16-O-15'-biaryl ether-linked dimer based on spectroscopic analyses (1H- and 13C-NMR, COSY, HMBC, and HSQCAD) and high-Resolution mass spectrometry analysis (Q-TOF). KW - Mycotoxin KW - Dimerization KW - HRMS KW - NMR PY - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-464940 SN - 1420-3049 VL - 23 IS - 10 SP - 2624 EP - 2628 PB - MDPI CY - Basel AN - OPUS4-46494 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -