TY - JOUR A1 - Keller, Julia A1 - Haase, H. A1 - Koch, Matthias T1 - Hydroxylation and dimerization of zearalenone: comparison of chemical, enzymatic and electrochemical oxidation methods N2 - Investigations of the metabolic pathway of mycotoxins by microsomal techniques are often laborious, causing an increasing demand for easy and rapid simulation methods. Thus, the non-microsomal oxidation technique of electrochemistry coupled online to mass spectrometry (EC/MS) was applied to simulate phase I biotransformation of the Fusarium mycotoxin zearalenone (ZEA). The obtained transformation products were identified by high resolution mass spectrometry (FT-ICR) and HPLC-MS/MS. Transformation products (TPs) from EC/MS were compared to those of other oxidative methods such as Fenton-like and Ce(IV) reactions and metabolites derived from in vitro assays (human and rat liver microsomes). Electrochemical oxidization of ZEA was achieved by applying a potential between 0 and 2,500 mV vs. Pd/H2 using a flow-through cell with a boron-doped diamond working electrode. Several mono-hydroxylated TPs were generated by EC/MS and Fenton-like reaction, which could also be found in microsomal in vitro assays. EC and Ce(IV) led to the formation of structurally different ZEA dimers and dimeric quinones probably connected over covalent biaryl C-C and C-O-C bonds. Although the dimerization of phenolic compounds is often observed in natural processes, ZEA dimers have not yet been reported. This is the first report on the formation of stable ZEA dimers and their related quinones. The tested non-microsomal methods, in particular EC/MS, could be useful in order to predict the biotransformation products of mycotoxins, even in cases where one to one simulation is not always feasible. KW - Electrochemistry KW - Zearalenone KW - Dimer PY - 2017 U6 - https://doi.org/10.3920/WMJ2017.2213 SN - 1875-0710 SN - 1875-0796 VL - 10 IS - 4 SP - 297 EP - 307 PB - Wageningen Academic Publishers AN - OPUS4-43393 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Keller, Julia A1 - Haase, Hajo A1 - Koch, Matthias T1 - Electrochemical simulation of biotransformation reactions of citrinin and dihydroergocristine compared to UV irradiation and Fenton-like reaction N2 - Mycotoxins occur widely in foodstuffs and cause a variety of mold-related health risks to humans and animals. Elucidation of the metabolic fate of mycotoxins and the growing number of newly discovered mycotoxins have enhanced the demand for fast and reliable simulation methods. The viability of electrochemistry coupled with mass spectrometry (EC/ESI-MS), Fenton-like oxidation, and UV irradiation for the simulation of oxidative phase I metabolism of the mycotoxins citrinin (CIT) and dihydroergocristine (DHEC) was investigated. The specific reaction products are compared with metabolites produced by human and rat liver microsomes in vitro. Depending on the applied potential between 0 and 2000 mV vs. Pd/H-2 by using a flow-through cell, CIT and DHEC are oxidized to various products. Besides dehydrogenation and dealkylation reactions, several hydroxylated DHEC and CIT species are produced by EC and Fenton-like reaction, separated and analyzed by LC-MS/MS and ESI-HRMS. Compared to reaction products from performed microsomal incubations, several mono- and dihydroxylated DHEC species were found to be similar to the reaction products of EC, Fenton-like reaction, and UV-induced oxidation. Consequentially, nonmicrosomal efficient and economic simulation techniques can be useful in early-stage metabolic studies, even if one-to-one simulation is not always feasible. KW - Mycotoxins KW - In vitro KW - Electrochemistry KW - Oxidation PY - 2017 U6 - https://doi.org/10.1007/s00216-017-0350-6 SN - 1618-2642 VL - 409 IS - 16 SP - 4037 EP - 4045 PB - Springer CY - Heidelberg AN - OPUS4-40492 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kotthoff, Lisa A1 - Keller, Julia A1 - Lörchner, Dominique A1 - Mekonnen, Tessema F. A1 - Koch, Matthias T1 - Transformation products of organic contaminants and residues - Overview of current simulation methods N2 - The formation of transformation products (TPs) from contaminants and residues is becoming an increasing focus of scientific community. All organic compounds can form different TPs, thus demonstrating the complexity and interdisciplinarity of this topic. The properties of TPs could stand in relation to the unchanged substance or be more harmful and persistent. To get important information about the generated TPs, methods are needed to simulate natural and manmade transformation processes. Current tools are based on metabolism studies, photochemical methods, electrochemical methods, and Fenton's reagent. Finally, most transformation processes are based on redox reactions. This review aims to compare these methods for structurally different compounds. The groups of pesticides, pharmaceuticals, brominated flame retardants, and mycotoxins were selected as important residues/contaminants relating to their worldwide occurrence and impact to health, food, and environmental safety issues. Thus, there is an increasing need for investigation of transformation processes and identification of TPs by fast and reliable methods. KW - Transformation product KW - Electrochemistry KW - Photochemistry KW - Fenton’s reagent PY - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-474108 SN - 1420-3049 VL - 24 IS - 4 SP - 753, 1 EP - 23 PB - MDPI CY - Basel AN - OPUS4-47410 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -