TY - JOUR A1 - Keller, Julia A1 - Borzekowski, Antje A1 - Haase, H. A1 - Menzel, R. A1 - Rueß, L. A1 - Koch, Matthias T1 - Toxicity assay for citrinin, zearalenone and zearalenone-14-sulfate using the nematode Caenorhabditis elegans as model organism N2 - To keep pace with the rising number of detected mycotoxins, there is a growing need for fast and reliable toxicity tests to assess the potential threat to food safety. Toxicity tests with the bacterial-feeding nematode Caenorhabditis elegans as model organism are well established. In this study the C. elegans wildtype strain N2 (var. Bristol) was used to investigate the toxic effects of the food-relevant mycotoxins citrinin (CIT) and zearalenone-14-sulfate (ZEA-14-S) and zearalenone (ZEA) on different life cycle parameters including reproduction, thermal and oxidative stress resistance and lifespan. The metabolization of the mycotoxins by the nematodes in vivo was investigated using HPLC-MS/MS. ZEA was metabolized in vivo to the reduced isomers α-zearalenol (α-ZEL) and β-ZEL. ZEA 14-S was reduced to α-/β-ZEL 14-sulfate and CIT was metabolized to mono-hydroxylated CIT. All mycotoxins tested led to a significant decrease in the number of nematode offspring produced. ZEA and CIT displayed negative effects on stress tolerance levels and for CIT an additional shortening of the mean lifespan was observed. In the case of ZEA-14-S, however, the mean lifespan was prolonged. The presented study shows the applicability of C. elegans for toxicity testing of emerging food mycotoxins for the purpose of assigning potential health threats. KW - Mycotoxins KW - Metabolization KW - Toxicity testing KW - Biotests PY - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-455772 VL - 10 IS - 7 SP - 284, 1 EP - 12 PB - MDPI AN - OPUS4-45577 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - 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 - Moldenhauer, Daniel A1 - Byrne, L. A1 - Haase, H. A1 - Resch-Genger, Ute A1 - Koch, Matthias T1 - Complexes of the mycotoxins citrinin and ochratoxin A with aluminum ions and their spectroscopic properties N2 - The sensitive detection of the mycotoxin citrinin (CIT) utilizing ist fluorescence requires approaches to enhance the emission. In this respect, we studied the complexation of CIT and ochratoxin A (OTA) with Al3+ in methanol using absorption and fluorescence spectroscopy. In this context, an isocratic high performance liquid chromatography (HPLC) method using a polymer column and a fluorescence detector was also developed that enables the separation of the metal ion complexes from the free ligands and non-complexed Al3+. CIT and OTA showed distinct changes in their absorption and fluorescence properties upon Al3+-coordination, and the fluorescence of CIT was considerably enhanced. Analysis of the photometrically assessed titration of CIT and OTA with Al3+ using the Job plot method revealed 1:2 and 1:1 stoichiometries for the Al3+ complexes of CIT (Al:CIT) and OTA (Al:OTA), respectively. In the case of CIT, only one -diketone moiety participates in Al3+ coordination. These findings can be elegantly exploited for signal amplification and provide the base to reduce the limit of detection for CIT quantification by about an order of magnitude, as revealed by HPLC measurements using a fluorescence detector. KW - Complexation KW - Aluminum KW - Fluorescence KW - Job plot KW - HPLC-DAD/FLD PY - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-470502 SN - 2072-6651 VL - 10 IS - 12 SP - 538, 1 EP - 8 PB - MDPI CY - Basel AN - OPUS4-47050 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 - TY - JOUR A1 - Kröcke, N. A1 - Grebenteuch, S. A1 - Keil, C. A1 - Demtröder, S. A1 - Koch, L. A1 - Thünemann, Andreas A1 - Benning, R. A1 - Haase, H. T1 - Effect of different drying methods on nutrient quality of the yellow mealworm (Tenebrio molitor L.) N2 - Yellow mealworm (Tenebrio molitor L.) represents a sustainable source of proteins and fatty acids for feed and food. Industrial production of mealworms necessitates optimized processing techniques, where drying as the first postharvest procedure is of utmost importance for the quality of the final product. This study examines the nutritional quality of mealworm larvae processed by rack oven drying, vacuum drying or freeze drying, respectively. Proximate composition and fatty acid profile were comparable between the dried larvae. In contrast, larvae color impressions and volatile compound profiles were very much dependent on processing procedure. High-temperature rack oven drying caused pronounced darkening with rather low content of volatiles, pointing toward the progress of Maillard reaction. On the other hand, vacuum drying or freeze drying led to enrichment of volatile Maillard reaction and lipid oxidation intermediates, whose actual sensory relevance needs to be clarified in the future. Beyond sensory and visual importance drying intermediates have to be considered with regard to their metal ion chelating ability; in particular for essential trace elements such as Zn2+. This study found comparable total zinc contents for the differently dried mealworm samples. However, dried larvae, in particular after rack oven drying, had only low zinc accessibility, which was between 20% and 40%. Therefore, bioaccessibility rather than total zinc has to be considered when their contribution to meeting the nutritional requirements for zinc in humans and animals is evaluated. KW - Food PY - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-476320 SN - 2075-4450 VL - 10 IS - 4 SP - 84, 1 EP - 13 PB - MDPI AN - OPUS4-47632 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kuner, Maximilian A1 - Lisec, Jan A1 - Mauch, Tatjana A1 - Konetzki, J. A1 - Haase, H. A1 - Koch, Matthias T1 - Quantification of Ergot Alkaloids via Lysergic Acid Hydrazide—Development and Comparison of a Sum Parameter Screening Method N2 - Ergot alkaloids are a group of mycotoxins occurring in products derived from various grasses (e.g., rye) and have been regulated in the EU recently. The new maximum levels refer to the sum of the six most common ergot alkaloids in their two stereoisomeric forms in different food matrices. Typically, these twelve compounds are individually quantified via HPLC-MS/MS or -FLD and subsequently summed up to evaluate food safety in a time-consuming process. Since all these structures share the same ergoline backbone, we developed a novel sum parameter method (SPM) targeting all ergot alkaloids simultaneously via lysergic acid hydrazide. After extraction and clean-up, in analogy to the current European standard method EN 17425 (ESM) for ergot alkaloid quantitation, the samples were derivatized by an optimized hydrazinolysis protocol, which allowed quantitative conversion after 20 min at 100 °C. The new SPM was evaluated against another established HPLC-FLD-based method (LFGB) and the HPLC-MS/MS-based ESM using six naturally contaminated rye and wheat matrix reference materials. While the SPM provided comparable values to the ESM, LFGB showed deviating results. Determined recovery rates, limits of detection and quantification of all three employed methods confirm that the new SPM is a promising alternative to the classical approaches for ergot alkaloid screening in food. KW - Ergot alkaloids KW - Sum Parameter KW - Mycotoxins KW - Derivatization KW - Hydrazinolysis PY - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-573968 SN - 0015-2684 VL - 28 IS - 9 SP - 3701 PB - MDPI CY - Basel AN - OPUS4-57396 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kuner, Maximilian A1 - Kühn, S. A1 - Haase, H. A1 - Meyer, Klas A1 - Koch, Matthias T1 - Cleaving Ergot Alkaloids by Hydrazinolysis - A Promising Approach for a Sum Parameter Screening Method N2 - Ergot alkaloids are mycotoxins formed by fungi of the Claviceps genus, which are some of the most common contaminants of food and feed worldwide. These toxins are a structurally heterogeneous group of compounds, sharing an ergoline backbone. Six structures and their corresponding stereoisomers are typically quantified by either HPLC-FLD or HPLC-MS/MS and the values subsequently summed up to determine the total ergot alkaloid content. For the development of a screening method targeting all ergot alkaloids simultaneously, the alkaloids need to be transferred to one homogeneous structure: a lysergic acid derivative. In this study, two promising cleaving methods—acidic esterification and hydrazinolysis—are compared, using dihydroergocristine as a model compound. While the acidic esterification proved to be unsuitable, due to long reaction times and oxidation sensitivity, hydrazinolysis reached a quantitative yield in 40-60 min. Parallel workup of several samples is possible. An increasing effect on the reaction rate by the addition of ammonium iodide was demonstrated. Application of hydrazinolysis to a major ergot alkaloid mix solution showed that all ergopeptines were cleaved, but ergometrine/-inine was barely affected. Still, hydrazinolysis is a suitable tool for the development of a sum parameter screening method for ergot alkaloids in food and feed. KW - Ergot alkaloids KW - Sum parameter method KW - Hydrazinolysis KW - Esterification PY - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-527508 VL - 13 IS - 5 SP - 342 PB - MDPI CY - Basel, Switzerland AN - OPUS4-52750 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -