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- Diaporthe toxica (2)
- Isotopic labeled internal standard (2)
- Mycotoxin (2)
- Stable isotope dilution assay (2)
- Alternaria mycotoxins (1)
- Biosynthesis (1)
- Bran (1)
- Deoxynivalenol (1)
- Dynamic covalent hydrazine chemistry (DCHC) (1)
- E-screen assay (1)
- Edible oil (1)
- Estrogenicity (1)
- European Reference Material (1)
- Flour extraction (1)
- Food (1)
- Food analysis (1)
- Fusarium mycotoxins (1)
- Fusarium toxins (1)
- Glucuronidation (1)
- Human recombinant UGT (1)
- Inter-fungal competition (1)
- Isomerisation (1)
- Isomerization (1)
- Isotope-dilution mass spectrometry (1)
- LC-MS/MS (1)
- Legume contamination (1)
- Lupins (1)
- MCF-7 (1)
- Maize germ oil (1)
- Masked mycotoxin (1)
- Mass spectrometry (1)
- Multi-mycotoxin analysis (1)
- Occurrence (1)
- Phase II metabolism (1)
- Phomopsin A (1)
- Phytopathogen (1)
- Quality assurance (1)
- Quantification (1)
- SIDA (1)
- Trichothecene (1)
- Trichothecenes (1)
- Type A trichothecenes (1)
- Uridine-diphosphoglucuronyltransferases (UGT) (1)
- ZEA (1)
- Zearalenone (1)
Mycotoxins are among the most abundant contaminants in food and feed worldwide. Therefore, in the EU maximum levels are established, e.g. for the frequently occurring Fusarium toxins deoxynivalenol (DON) and zearalenone (ZEA). Additional to DON and ZEA, modified mycotoxins are present in naturally contaminated grain products contributing significantly to the exposure of humans and animals with mycotoxins. Up to now data on the spatial distribution of many (masked) mycotoxins in the kernels of wheat are missing. The aim of the present study was to investigate the amounts of DON and ZEA as well as their most abundant derivatives DON-3-glucoside (DON-3G), 3- and 15-acetyl-DON, ZEA-14- and 16-glucoside and ZEA-14-sulphate (ZEA-14S) in mill fractions of naturally contaminated wheat batches using HPLC-MS/MS. The investigated distribution pattern in ten milling fractions is comparable among the three investigated different wheat batches. Interestingly, DON and DON-3G were found to be present to similar amounts in all fractions. In bran, the levels were only slightly higher than in the endosperm. By contrast, for ZEA and ZEA-14S a significantly higher amount of toxin is located in the fibre-rich fractions. The relative mass proportion of DON-3G comprises for only between 2.9 and 11.2% of the free DON, while the relative mass proportion of ZEA-14S is estimated to even exceed the amount of free ZEA in certain fractions. Acetylated DON derivatives and ZEA-glucosides were only detected in low amounts. The experimental results show that a significant reduction of the ZEA and ZEA-14S level in wheat flour is feasible by applying milling technology strategies. However, the almost evenly distribution of DON and DON-3G in all fractions does not allow for the technological removal of relevant toxin amounts. Furthermore, the relative share of masked forms was higher for ZEA derivatives than for the DON conjugates in the investigated wheat lots.
Trichothecene mycotoxins, with T-2 and HT-2 toxins being the main representatives of the type A subgroup, are naturally and worldwide occurring contaminants frequently found in grain-based food and feed. Due to the high consumption of these products and the potential health risk associated herewith, concerns about the safety and quality of food and feed have increased over the last decades at both governmental and consumer levels. Since it is not possible to avoid their occurrence, tremendous efforts have been performed to identify and monitor mycotoxins in food and feed to make their consumption safe. However, suitable certified reference materials (CRMs) intended for quality assurance and quality control purposes are still lacking for many mycotoxin-matrix combinations. Therefore, in the framework of a European Reference Material (ERM®) project, the first CRM for T-2 and HT-2 toxin in ground oat flakes (ERM®-BC720) was developed according to the requirements of ISO Guide 35. The whole process of ERM®-BC720 development, including sample preparation, homogeneity and stability studies and value assignment, is presented. The assignment of the certified mass fractions was based upon an in-house study using high-performance liquid chromatography isotope-dilution tandem mass spectrometry. Simultaneously, an interlaboratory comparison study involving 24 expert laboratories was conducted in order to support the in-house certification study. The certified values and their corresponding expanded uncertainties (k=2) for both T-2 and HT-2 toxin in ERM®-BC720, traceable to the international system of units, are (82±4) µg kg-1 and (81±4) µg kg-1, respectively.
Established maximum levels for the mycotoxin zearalenone (ZEN) in edible oil require monitoring by reliable analytical methods. Therefore, an automated SPE-HPLC online system based on dynamic covalent hydrazine chemistry has been developed. The SPE step comprises a reversible hydrazone formation by ZEN and a hydrazine moiety covalently attached to a solid phase. Seven hydrazine materials with different properties regarding the resin backbone, pore size, particle size, specific surface area, and loading have been evaluated. As a result, a hydrazine-functionalized silica gel was chosen. The final automated online method was validated and applied to the analysis of three maize germ oil samples including a provisionally certified reference material. Important performance criteria for the recovery (70–120 %) and precision (RSDr <25 %) as set by the Commission Regulation EC 401/2006 were fulfilled: The mean recovery was 78 % and RSDr did not exceed 8 %. The results of the SPE-HPLC online method were further compared to results obtained by liquid&–liquid extraction with stable isotope dilution analysis LC-MS/MS and found to be in good agreement. The developed SPE-HPLC online system with fluorescence detection allows a reliable, accurate, and sensitive quantification (limit of quantification, 30 µg/kg) of ZEN in edible oils while significantly reducing the workload. To our knowledge, this is the first report on an automated SPE-HPLC method based on a covalent SPE approach.
The role of mycotoxins in the microbial competition in an ecosystem or on the same host plant is still unclear. Therefore, a laboratory study was conducted to evaluate the influence of mycotoxins on growth and mycotoxin production of Fusarium and Alternaria fungi. Fusarium culmorum Fc13, Fusarium graminearum Fg23 and two Alternaria tenuissima isolates (At18 and At220) were incubated on wheat kernels supplemented with alternariol (AOH), tetramic acid derivates (TeA), deoxynivalenol (DON) and zearalenone (ZEA) in an in vitro test system. Fungal biomass was quantified by determining ergosterol content. Three Fusarium toxins (DON, nivalenol and ZEA) and three Alternaria toxins (AOH, alternariol methyl ether (AME) and altenuene) were analysed by HPLC-MS/MS. If Alternaria strains grew in wheat kernels spiked with Fusarium mycotoxins, their growth rates were moderately increased, their AOH and AME production was enhanced and they were simultaneously capable of degrading the Fusarium mycotoxins DON and ZEA. In contrast, both Fusarium strains behaved quite differently. The growth rate of Fc13 was not distinctly influenced, while Fg23 increased its growth in wheat kernels spiked with AOH. TeA depressed the ergosterol content in Fc13 as well as in Fg23. The DON production of Fc13 was slightly depressed, whereas the ZEA production was significantly increased. In contrast, Fg23 restricted its ZEA production. Both Fusarium strains were not capable of degrading the Alternaria mycotoxin AOH. Mycotoxins might play an important role in the interfungal competitive processes. They influence growth rates and mycotoxin production of the antagonistic combatants. The observed effects between phytopathogenic Alternaria and Fusarium strains and their mycotoxins aid the understanding of the complexity of microbial competitive behaviour in natural environments.
Die Prozesskontaminante Acrylamid steht im Verdacht krebserregend und erbgutverändernd zu sein, weshalb große Anstrengungen unternommen werden, um die Acrylamidgehalte in Lebensmitteln auf möglichst niedrige Werte zu reduzieren. Durch Anwendung des dynamischen Minimierungskonzepts konnte über die letzten Jahre in Deutschland eine deutliche Verringerung der mittleren täglichen Acrylamidaufnahme pro kg Körpergewicht erreicht werden, wobei die durch häusliche Zubereitung (Braten, Backen, Frittieren) entstehenden als auch die durch den Verzehr weiterer relevanter Lebensmittel wie Kakao und Kakaoerzeugnisse aufgenommenen Acrylamidmengen nicht oder nur marginal berücksichtigt werden.
Für die Ermittlung der Acrylamidbelastungen in Schokoladen unterschiedlicher Kakaogehalte sowie in reinem Kakaopulver wurden insgesamt 140 Proben aus deutschen Einzelhandelsmärkten untersucht. Die quantitative Bestimmung erfolgte unter Verwendung eines schnellen, kostengünstigen und validierten HPLC-MS/MS-basierten Analysenverfahrens in Kombination mit der Stabilisotopenverdünnungsanalyse (SIVA). In allen untersuchten Proben konnte Acrylamid nachgewiesen werden, wobei Gehalte im Bereich von 9,0-1747 µg kg-1 mit relativen Standardabweichungen zwischen 0,4 % und 10,8 % ermittelt wurden.
Zearalenone and its cis-isomer, cis-zearalenone, are nonsteroidal mycotoxins that elicit an estrogenic response upon binding to the estrogen receptor. This study compares the estrogenicity of eleven congeners including novel metabolites as 15-OH-zearalenone, zearalenone-14-sulfate, α-cis-zearalenol and β-cis-zearalenol using the E-Screen assay. Overall, a change in the configuration from trans to cis retains significant estrogenic activity. In contrast, alterations of the aromatic moiety including hydroxylation and sulfation showed a markedly decreased estrogenicity when compared to zearalenone.
A novel method for the determination of phomopsin A (1) in lupin flour, pea flour, and bean flour as well as whole lupin plants was established based on stable isotope dilution assay (SIDA) LC-MS/MS using 15N6-1 as an isotopically labeled internal standard. Artificially infected samples were used to develop an optimized extraction procedure and sample pretreatment. The limits of detection were 0.5–1 µg/kg for all matrices. The limits of quantitation were 2–4 µg/kg. The method was used to analyze flour samples generated from selected legume seeds and lupin plant samples that had been inoculated with Diaporthe toxica and two further fungal strains. Finally, growing lupin plants infected with D. toxica were investigated to simulate a naturally in-field mycotoxicosis. Toxin levels of up to 10.1 µg/kg of 1 were found in the pods and 7.2 µg/kg in the stems and leaves.
The mycotoxin deoxynivalenol (DON), formed by Fusarium species, is one of the most abundant mycotoxins contaminating food and feed worldwide. Upon ingestion, the majority of the toxin is excreted by humans and animal species as glucuronide conjugate. First in vitro data indicated that DON phase II metabolism is strongly species dependent. However, kinetic data on the in vitro metabolism as well as investigations on the specific enzymes responsible for DON glucuronidation in human are lacking. In the present study, the DON metabolism was investigated using human microsomal fractions and uridine-diphosphoglucuronyltransferases (UGTs) as well as liver microsomes from five animal species. Only two of the twelve tested human recombinant UGTs led to the formation of DON glucuronides with a different regiospecificity. UGT2B4 predominantly catalyzed the formation of DON-15-O-glucuronide (DON-15GlcA), while for UGT2B7 the DON-3-O-glucuronide (DON-3GlcA) metabolite prevailed. For human UGTs, liver, and intestinal microsomes, the glucuronidation activities were low. The estimated apparent intrinsic clearance (Clapp,int) for all human UGT as well as tissue homogenates was <1 mL/min mg protein. For the animal liver microsomes, moderate Clapp,int between 1.5 and 10 mL/min mg protein were calculated for carp, trout, and porcine liver. An elevated glucuronidation activity was detected for rat and bovine liver microsomes leading to Clapp,int between 20 and 80 mL/min mg protein. The obtained in vitro data points out that none of the animal models is suitable for estimating the human DON metabolism with respect to the metabolite pattern and formation rate.
The hepatotoxin phomopsin A (PHO-A), a secondary metabolite mainly produced by the fungus Diaporthe toxica, occurs predominantly on sweet lupins. Along with the growing interest in sweet lupins for food and feed commodities, concerns have been raised about fungal infestations, and consequently, about the determination of PHO-A.
High performance liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) represents the most suitable analytical technique for sensitive and selective detection of mycotoxins including PHO-A. However, isotopic labeled substances are needed as internal standards for a reliable and convenient quantification.
As no isotope standard for PHO-A is currently available, a biosynthesis of fully 15N6-labeled PHO-A was established by cultivation of D. toxica on defined media containing Na15NO3 and 15N-labeled yeast extract as the only nitrogen sources. The identity of 15N6-PHO-A was confirmed by high resolution mass spectrometry.
The new 15N6-labeled standard will facilitate the method development for PHO-A including a more accurate quantification by LC-MS/MS.