Fabrication of amino- and hydroxyl dual-functionalized magnetic microporous organic network for extraction of zearalenone from traditional Chinese medicine prior to the HPLC determination.

Efficient enrichment of trace zearalenone (ZEN) from the complex traditional Chinese medicine (TCM) samples is quite difficult, but of great significance for TCM quality control. Herein, we reported a novel magnetic solid phase extraction (MSPE) strategy for ZEN enrichment using the amino- and hydroxyl dual-functionalized magnetic microporous organic network (Fe3O4@MON-NH2-OH) as an advanced adsorbent combined with the high-performance liquid chromatography (HPLC) determination. Efficient extraction of ZEN was achieved via the possible hydrogen bonding, hydrophobic, and π-π interactions between Fe3O4@MON-NH2-OH and ZEN. The adsorption capacity of Fe3O4@MON-NH2-OH for ZEN was 215.0 mg g-1 at the room temperature, which was much higher than most of the reported adsorbents. Under the optimal condition, the developed Fe3O4@MON-NH2-OH-MSPE-HPLC method exhibited wide linear range (5-2500 µg L-1), low limits of detection (1.4-35 µg L-1), less adsorbent consumption (5 mg), and large enhancement factor (95) for ZEN. The proposed method was successfully applied to detect trace ZEN from 10 kinds of real TCM samples. Conclusively, this work demonstrates the Fe3O4@MON-NH2-OH can effectively extract trace ZEN from the complex TCM matrices, which may open up a new way for the application of MONs in the enrichment and extraction of trace contaminants or active constituents from the complex TCM samples.

Magnetic aptamer copper nanoclusters fluorescent biosensor for the visual detection of zearalenone based on docking-aided rational tailoring.

To address the food safety issues caused by toxins, we established a fluorescent copper nanocluster biosensor based on magnetic aptamer for the visual and quantitative detection of ZEN. Specifically, we utilized the docking-aided rational tailoring (DART) strategy to analyze intermolecular force and interaction sites between zearalenone (ZEN) and the aptamer, and optimize the long-chain aptamer step by step to enhance the binding affinity by 3.4 times. The magnetic bead-modified aptamer underwent conformational changes when competing with complementary sequences to bind with ZEN. Then, the released complementary sequences will be amplified in template-free mode with the presence of the terminal deoxynucleotidyl transferase (TdT), and generating T-rich sequences as the core sequences for the luminescence of copper nanoclusters. The luminescence could be visualized and quantitatively detected through ultraviolet irradiation. The proposed label-free aptasensor exhibited high sensitivity and specificity, with a low limit of detection (LOD) of 0.1 ng/mL.

Simultaneous removal of aflatoxin B1 and zearalenone in vegetable oils by hierarchical fungal mycelia@graphene oxide@Fe3O4 adsorbent.

Physical adsorbents for detoxification are widely used in vegetable oil industry. So far, the high-efficiency and low-cost adsorbents have not been well explored. Here, a hierarchical fungal mycelia@graphene oxide@Fe3O4 (FM@GO@Fe3O4) was fabricated as an efficient adsorbent for simultaneous removal of aflatoxin B1 (AFB1) and zearalenone (ZEN). The morphological, functional and structural characteristics of the prepared adsorbents were systematic investigated. Batch adsorption experiments in both single and binary systems were conducted, and the adsorption behaviours and mechanism were explored. The results indicated that the adsorption process occurred spontaneously and the mycotoxin adsorption could be described as physisorption through hydrogen bonding, π-π stacking, electrostatic and hydrophobic interactions. Due to good biological safety, magnetic manipulability, scalability, recyclability and easy regeneration, FM@GO@Fe3O4 performance is suitable for application as a detoxification adsorbent in vegetable oil industry. Our study addresses a novel green strategy for removing multiple mycotoxins by integrating the toxigenic isolates with advanced nanomaterials.

Synthesised magnetic nano-zeolite as a mycotoxins binder to reduce the toxicity of aflatoxins, zearalenone, ochratoxin A, and deoxynivalenol in barley.

Agricultural commodities, particularly cereals can be contaminated with mycotoxins during the pre- and post-harvest stage. The main goal of this study was to evaluate the efficacy of magnetic zeolite nanocomposite (MZNC) as an adsorbent for the reduction of mycotoxins in barley flour. The MZNC is synthesised using an eco-friendly and efficient procedure and characterised by zeta potential, field emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The adsorbent amount that affects the adsorption capacity was optimised. Low amounts of the nanocomposite removed >99% of aflatoxins, 50% of ochratoxin A, 22% of zearalenone, and 1.8% of the deoxynivalenol from the contaminated sample and adsorption by MZNC was better than the natural zeolite; this phenomenon is related to the wide surface of nanocomposites. Results provide new insights into possible future research that could overcome the challenges of using nanotechnology to eliminate mycotoxins from agricultural products. It can be hoped that the presence of cheap and eco-friendly mycotoxin binders such as the MZNC that is synthesised and utilised in this research will help to produce secure food and feed products.

Degradation of Aflatoxin B1 and Zearalenone by Bacterial and Fungal Laccases in Presence of Structurally Defined Chemicals and Complex Natural Mediators.

Aflatoxin B1 (AFB1) and zearalenone (ZEN) exert deleterious effects to human and animal health. In this study, the ability of a CotA laccase from Bacillus subtilis (BsCotA) to degrade these two mycotoxins was first investigated. Among the nine structurally defined chemical compounds, methyl syringate was the most efficient mediator assisting BsCotA to degrade AFB1 (98.0%) and ZEN (100.0%). BsCotA could also use plant extracts, including the Epimedium brevicornu, Cucumis sativus L., Lavandula angustifolia, and Schizonepeta tenuifolia extracts to degrade AFB1 and ZEN. Using hydra and BLYES as indicators, it was demonstrated that the degraded products of AFB1 and ZEN using the laccase/mediator systems were detoxified. Finally, a laccase of fungal origin was also able to degrade AFB1 and ZEN in the presence of the discovered mediators. The findings shed light on the possibility of using laccases and a mediator, particularly a natural plant-derived complex mediator, to simultaneously degrade AFB1 and ZEN contaminants in food and feed.

A holistic study to understand the detoxification of mycotoxins in maize and impact on its molecular integrity using cold atmospheric plasma treatment.

The need for safe and quality food, free from the presence of hazardous contaminants such as mycotoxins is an on-going and complex challenge. Cold atmospheric pressure plasma (CAPP) has the potential to contribute to achieving this goal. Decontamination efficacy of CAPP against six of the most common mycotoxins found in foods and feedstuffs was assessed herein. Concentration reduction of up to 66% was achieved in maize for both aflatoxin B1 and fumonisin B1. Degradation products were detected only in the case of aflatoxin B1 and zearalenone and were tested on human hepatocarcinoma cells with no increase in cytotoxicity observed. Analysis of treated maize revealed substantial changes to small molecular mass components of the matrix. While CAPP shows promise in terms of mycotoxin detoxification important questions concerning potential changes to the nutritional and safety status of the food matrix require further investigations.

Biosorptive detoxification of zearalenone biotoxin by surface-modified renewable biomass: process dynamics and application.

BACKGROUND: Contamination of food, feed, beverages and even drinking water with biotoxins is a growing global concern because of their potential health risks. In this work, surface-modified sugar beet pulp waste was used for the biosorptive removal of zearalenone biotoxin from contaminated aquatic media. RESULTS: Infrared, Boehm titration, BET (Brunauer-Emmett-Teller) surface area and point of zero charge analysis were employed for surface characterization. Kinetic and equilibrium studies showed that biotoxin biosorption was well predicted by the pseudo-second-order kinetic model and the Langmuir isotherm model. Zearalenone was removed from the solution over a wide pH range (3.0-8.0) and within a short time (15 min). Maximum uptake capacity of modified biomass was recorded as 23.30 ± 0.17 g kg-1 . Highest removal yield in a dynamic flow mode (94.56 ± 0.13%) was achieved at 2 mL min-1 flow rate using 30 mg biosorbent. Regeneration experiments revealed high reusability potential of suggested biosorbent. Moreover, its application potential was tested in spiked samples of malt, beer and canned corn liquid. CONCLUSION: Detoxification potential of this renewable biomass was significantly enhanced after modification. Modified biomass could be used as an efficient and low-cost green-type material with good application potential for zearalenone detoxification. © 2018 Society of Chemical Industry.

[Determination of zearalenone and α-zearalenol in vegetable oil and grain products by C_(18)-Al_2O_3 solid phase extraction column purification coupled with ultra-performance liquid chromatography tandem mass spectrometry].

OBJECTIVE: To develop a method for simultaneous determination of zearalenone( ZEN) and α-zearalenol( α-ZEL) in vegetable oil and grain products by solid phase extraction column purification coupled with ultra-performance liquid chromatography tandem mass spectrometry. METHODS: Firstly, ZEN and α-ZEL in grain products were extracted by hexane/ethyl acetate( 50 : 50, V/V), and then extracted as vegetable oil by acetonitrile-water solution( 90: 10, V/V), and purified by C_(18)-Al_2O_3 solid phase extraction column. ZEN and α-ZEL was separated by UPLC with acetonitrile-water gradient elution on C_(18) column( 2. 1 mm × 100 mm, 1. 6 µm), and qualified/quantified by mass spectrometry with ESI negative MRM mode with ~(13)C_(18)-zearalenone as internal standard. RESULTS: The linearity of ZEN and α-ZEL ranged from 1. 0-500 ng/mL. The limit of detection for ZEN and α-ZEL in vegetable oil and grain products was 0. 3 and 0. 2 µg/kg, respectively. The limit of quantification for ZEN and α-ZEL in vegetable oil and grain products was 1. 0 and 0. 5 µg/kg. The average recoveries of ZEN and α-ZEL for spiked samples of 1. 0-100 µg/kg were 93. 5%-108. 0% and 92. 0%-105. 0%. The relative standard deviations of ZEN and α-ZEL were 3. 2%-8. 5% and 4. 6%-7. 8%( n = 6). 55 samples sold in Hangzhou supermarkets were analyzed. ZEN was detected in all corn germ oil with median and maximum contents of 126. 2 and 453. 1 µg/kg. α-ZEL was detected in 50% corn germ oil with median and maximum contents of 2. 0 and 5. 0µg/kg. CONCLUSION: The method possesses several advantages including sensitivity, precision, good efficiency of purification, simplicity and economy, and it is applicable to the batch analysis of zearalenone and α-zearalenol in vegetable oil and grain products.

Metabolomics Reveals that Dietary Xenoestrogens Alter Cellular Metabolism Induced by Palbociclib/Letrozole Combination Cancer Therapy.

Recently, the palbociclib/letrozole combination therapy was granted accelerated US FDA approval for the treatment of estrogen receptor (ER)-positive breast cancer. Since the underlying metabolic effects of these drugs are yet unknown, we investigated their synergism at the metabolome level in MCF-7 cells. As xenoestrogens interact with the ER, we additionally aimed at deciphering the impact of the phytoestrogen genistein and the estrogenic mycotoxin zearalenone. A global metabolomics approach was applied to unravel metabolite and pathway modifications. The results clearly showed that the combined effects of palbociclib and letrozole on cellular metabolism were far more pronounced than that of each agent alone and potently influenced by xenoestrogens. This behavior was confirmed in proliferation experiments and functional assays. Specifically, amino acids and central carbon metabolites were attenuated, while higher abundances were observed for fatty acids and most nucleic acid-related metabolites. Interestingly, exposure to model xenoestrogens appeared to counteract these effects.

Studies of Lipid Monolayers Prepared from Native and Model Plant Membranes in Their Interaction with Zearalenone and Its Mixture with Selenium Ions.

The impact of zearalenone and selenate ions on the monolayers of 1,2-dipalmitoyl-phosphatidylcholine (DPPC), 1,2-dipalmitoyl-3-trimethylammonium-propane (DPTAP), and the lipid mixtures (phospholipids and galactolipids) extracted from wheat plasmalemma has been studied using Langmuir trough technique and Brewster angle microscopy (BAM). The zearalenone is a mycotoxin that exerts toxic effects on the cells of plants and animals. Monolayers' properties were characterized by surface pressure (π)-molecular area (A) isotherms. It was found that zearalenone interacts with lipid monolayers causing their expansion. The selenate ions, added to the subphase together with zearalenone, reduce the effect of this mycotoxin on the surface properties of lipid films.

Metabolomics-Guided Isolation of Anti-trypanosomal Metabolites from the Endophytic Fungus Lasiodiplodia theobromae.

Fungal endophytes offer diverse and unique secondary metabolites, making these organisms potential sources of promising drug leads. The application of high-resolution-liquid chromatography mass spectrometry and nuclear magnetic resonance-based metabolomics to fungal endophytes is practical in terms of dereplication studies and the mining of bioactive compounds. In this paper, we report the application of metabolomics in parallel with anti-trypanosomal assays to determine the ideal conditions for the medium-scale fermentation of the endophyte Lasiodiplodia theobromae. The 1H NMR comparison between the active versus inactive fractions identified several unique chemical fingerprints belonging to the active fractions. Furthermore, by integrating high-resolution-liquid chromatography mass spectrometry data with multivariate data analysis, such as orthogonal partial least squares-discriminant analysis (OPLS-DA) and the bioactivity results of the fractions of L. theobromae, the anti-trypanosomal agents were easily discerned. With available databases such as Antibase and Dictionary of Natural Products coupled to MZmine through in-house algorithms optimized in our laboratory, the predicted metabolites were readily identified prior to isolation. Fractionation was performed on the active fractions and three known compounds were isolated, namely, cladospirone B, desmethyl-lasiodiplodin, and R-(-)-mellein. Cladospirone B and desmethyl-lasiodiplodin were among the predicted compounds generated by the OPLS-DA S-plot, and these compounds exhibited good activity against Trypanosoma brucei brucei with minimum inhibitory concentrations of 17.8 µM and 22.5 µM, respectively.

Selective inhibition of p97 by chlorinated analogues of dehydrocurvularin.

The ATPase p97 is a ubiquitin targeted segregase that uses the energy of ATP binding and hydrolysis to extract ubiquitylated substrates from biological membranes, from other proteins, or from protein complexes to carry out myriad tasks in eukaryotes. Increased p97 activity has been linked to a poor prognosis in cancer patients, making p97 an anti-neoplastic target. In the present study, we show that dehydrocurvularin (DHC) and its chlorinated variants are covalent inhibitors of p97, interfering with its ATPase activity. Interestingly, cellular studies revealed both DHC and its monochloro analogue interfere with both the proteasome and p97, whereas its dichloro analogue showed p97 specificity.

Simultaneous determination of zearalenone and its derivatives in edible vegetable oil by gel permeation chromatography and gas chromatography-triple quadrupole mass spectrometry.

A sensitive gas chromatographic-triple quadrupole mass spectrometric (GC-QqQ MS) analytical method, for the determination of zearalenone and its five derivatives in edible vegetable oil, was developed. After the vegetable oil samples were prepared using gel permeation chromatography, the eluent was collected, evaporated and dried with nitrogen gas. The residue was silylated with N,O-bis-trimethylsilyltrifluoroacetamide, containing 1% trimethylchlorosilane. GC-QqQ MS was performed in the reaction-monitoring mode to confirm and quantify mycotoxins in vegetable oil. The limits of quantitation were 0.03-0.2 µg kg(-1) for the six mycotoxins. The average recoveries, measured at 2, 20 and 200 µg kg(-1), were in the range 80.3-96.5%. Zearalenone was detected in the range 5.2-184.6 µg kg(-1) in nine maize oils and at 40.7 µg kg(-1) in a rapeseed oil from the local market.

Antioxidant activities and phenolics of fermented Bletilla formosana with eight plant pathogen fungi.

The tubers of Bletilla formosana were fermented with eight plant pathogen fungi, respectively, and antioxidant activities and total phenolic content (TPC) of the crude extracts of fermented products and non-fermented products were investigated. The antioxidant activities were evaluated in three different test systems [DPPH, ABTS radical-scavenging activity, and ferric reducing-antioxidant power (FRAP)]. It was found that the extract of Helminthosporium maydis fermented B. formosana (FBF) possessed the highest TPC and exhibited a significant antioxidant activity compared with non-fermented product and other fermented products. Correlation analysis between antioxidant activities and TPC was also investigated. The good correlation between antioxidant activities and TPC revealed that the phenolic compounds might be the major contributors for the high antioxidant activities of the fermented B. formosana. Two phenolic compounds, curvularin and dehydrocurvularin, were isolated from H. maydis FBF, which had never been reported from plant of orchidaceae or H. maydis. Curvularin exhibited significant antioxidant activities, and was also present at a high concentration (0.373 mg/mg extract sample), implying an important role for the antioxidant activity of H. maydis FBF. This study suggested that proper fermentation processing could improve TPC and antioxidant activities of B. formosana.

Photochemical trans-/cis-isomerization and quantitation of zearalenone in edible oils.

The emphasis of the present work was to investigate the photochemical conversion of trans- to cis-zearalenone in edible oils under real-life conditions. For quantitation purposes a cis-zearalenone standard was synthesized and characterized for its identity and purity (≥95%) by (1)H NMR, X-ray crystallography, HPLC fluorescence and mass spectrometric detection. In a sample survey of 12 edible oils (9 corn oils, 3 hempseed oils) from local supermarkets all corn oils contained trans-zearalenone (median 194 µg/kg), but no cis-zearalenone was detected. For alteration studies trans-zearalenone contaminated corn oils were exposed to sunlight over 4 and 30 weeks, revealing an obvious shift toward cis-zearalenone up to a cis/trans ratio of 9:1 by storage in colorless glass bottles. Irradiation experiments of trans-zearalenone in different organic solvents confirmed the preferred formation of cis-zearalenone possibly caused by entropic effects rather than by enthalpic entities as investigated by quantum chemical and classical force field simulations.

Effect on hepatonephric organs, serum metabolites and oxidative stress in post-weaning piglets fed purified zearalenone-contaminated diets with or without Calibrin-Z.

The objectives of this study were to investigate the toxicity of zearalenone (ZEA) on hepatonephric organs, serum metabolites and oxidative stress of piglets and to evaluate the efficacy of Calibrin-Z (CAZ) in preventing ZEA-induced adverse effects. The experiment was conducted for 22 days using 36 piglets weaned at 21 days of age (Landrace × Yorkshire × Duroc, 18 females and 18 males; 8.84 ± 0.21 kg average body weight). Piglets of each gender were randomly allocated to the following six dietary treatments: (i) Control (basal diet only); (ii) Control + 1 g/kg CAZ; (iii) Control + 1 mg/kg ZEA; (iv) Control + 1 mg/kg ZEA + 1 g/kg CAZ; (v) Control + 1 mg/kg ZEA + 2 g/kg CAZ; (vi) Control + 1 mg/kg ZEA + 4 g/kg CAZ. Piglets were housed and fed individually for the entire experimental period. Blood samples were taken, and piglets were killed at the end of the experiment to obtain organs for physiological assessment. Results showed that piglets fed the ZEA-contaminated diet had increased (p < 0.05) activities of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, gamma-glutamyltransferase (GGT), creatine kinase and cholinesterase, concentrations of urea, and creatinine in serum, and malondialdehyde (MDA) in serum and liver. Pigs fed the ZEA-only diet also showed reductions in serum (p < 0.05) globulin, triglycerides and high-density lipoproteins (HDL), and reductions in total superoxide dismutase (TSOD) and glutathione peroxidase (GSHPx) activity in both serum and liver. Supplementation of CAZ at the dosages of 1-4 g/kg to the diet containing 1.05 mg/kg ZEA linearly increased (p < 0.05) concentrations of triglycerides and HDL in serum, activity of TSOD and GSHPx in serum and liver, but linearly reduced (p < 0.05) all tested serum enzymes and lowered (p < 0.05) the elevated concentrations of urea, and creatinine in serum, and MDA in serum and liver caused by dietary ZEA. Piglets fed the ZEA-contaminated diet showed increased (p < 0.05) relative weight of liver and kidney compared with the control, whereas only numerical improvement on relative weight of liver and kidney was observed with simultaneous addition of CAZ at 4 g/kg diet and ZEA. However, feeding the diet with CAZ alone at 1 g/kg had no impact on any of the measured parameters when compared to the control. It is suggested that feeding ZEA at 1.05 mg/kg exerted a deleterious effect on piglets, which was totally or partly ameliorated by dietary supplementation of CAZ at concentrations between 1 and 4 g/kg diet.

Determination of zearalenone in botanical dietary supplements, soybeans, grains, and grain products by immunoaffinity column cleanup and liquid chromatography: single-laboratory validation.

The accuracy, repeatability, and reproducibility characteristics of a method for measuring levels of zearalenone (ZON) in botanical root products, soybeans, grains, and grain products were determined by an AOAC single-laboratory validation procedure. Replicates of 10 test portions of each powdered root product (black cohosh, ginger, ginseng), brown rice flour, brown rice grain, oat flour, rice bran, soybeans, and wheat flour at each spiking level (ZON at 0, 50, 100, and 200 microg/kg) were analyzed on 3 separate days. Test samples were extracted with methanol-water (75 + 25, v/v). The extracts were centrifuged or filtered, diluted with phosphate-buffered saline (PBS) containing 0.5% Tween 20, and filtered; the filtrates were applied to an immunoaffinity column containing antibodies specific for ZON. After the column was washed with methanol-PBS (15 + 85, v/v) containing 0.5% Tween 20 and then with water, the toxin was eluted from the column with methanol, and the eluate was diluted with water. The eluate containing the toxin was then subjected to RPLC with fluorescence detection. All commodities that were found to contain ZON at < 10 microg/kg were used for the recovery study. The average within-day and between-days recoveries of ZON added at levels of 50-200 microg/kg ranged from 82 to 88% and from 81 to 84%, respectively, for all test commodities. The total average of within- and between-day SD and RSDr values for all test commodities ranged from 2.5 to 7.3 microg/kg and from 4.6 to 6.2%, respectively. HorRat values were <1.3 for all matrixes examined. The tested method was found to be acceptable for the matrixes examined.

A rapid method for simultaneous determination of zearalenone, α-zearalenol, ß-zearalenol, zearalanone, α-zearalanol and ß-zearalanol in traditional Chinese medicines by ultra-high-performance liquid chromatography-tandem mass spectrometry.

A rapid and reliable ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for simultaneous determination of zearalenone (ZEN), α-zearalenol (α-ZOL), ß-zearalenol (ß-ZOL), zearalanone (ZAN), α-zearalanol (α-ZAL) and ß-zearalanol (ß-ZAL) in traditional Chinese medicines (TCMs) was developed. The development of the method and investigations of the matrix influence were described in particular. After evaluation of the matrix effects of different TCMs, i.e., rhizomes and roots, seeds, flowers, grasses and leaves, by the post-extraction spiked method, a reliable sample clean-up method based on home-made clean-up cartridges, a suitable internal standard and the matrix calibration were combined using to minimize the matrix effects to ensure the accuracy of the method. The established method was further validated by determining the linearity (R(2)≥0.9990), sensitivity (limit of quantitation 0.11-0.99 ng mL(-1)), average recovery (86.6-113.5%) and precision (relative standard deviation ≤13.5%). It was shown to be a suitable method for simultaneous determination of ZEN, α-ZOL, ß-ZOL, ZAN, α-ZAL and ß-ZAL in different TCMs. Finally, the established method was successfully applied to the determination of the six mycotoxins in various TCMs and the results were presented to provide relevant insights to researchers in TCM analysis.

Dynamic covalent hydrazine chemistry as a selective extraction and cleanup technique for the quantification of the Fusarium mycotoxin zearalenone in edible oils.

A novel, cost-efficient method for the analytical extraction of the Fusarium mycotoxin zearalenone (ZON) from edible oils by dynamic covalent hydrazine chemistry (DCHC) was developed and validated for its application with high performance liquid chromatography-fluorescence detection (HPLC-FLD). ZON is extracted from the edible oil by hydrazone formation on a polymer resin functionalised with hydrazine groups and subsequently released by hydrolysis. Specifity and precision of this approach are superior to liquid partitioning or gel permeation chromatography (GPC). DCHC also extracts zearalanone (ZAN) but not alpha-/beta-zearalenol or -zearalanol. The hydrodynamic properties of ZON, which were estimated using molecular simulation data, indicate that the compound is unaffected by nanofiltration through the resin pores and thus selectively extracted. The method's levels of detection and quantification are 10 and 30 microg/kg, using 0.2g of sample. Linearity is given in the range of 10-20,000 microg/kg, the average recovery being 89%. Bias and relative standard deviations do not exceed 7%. In a sample survey of 44 commercial edible oils based on various agricultural commodities (maize, olives, nuts, seeds, etc.) ZON was detected in four maize oil samples, the average content in the positive samples being 99 microg/kg. The HPLC-FLD results were confirmed by HPLC-tandem mass spectrometry and compared to those obtained by a liquid partitioning based sample preparation procedure.

Changes in metallothionein level in rat hepatic tissue after administration of natural mouldy wheat.

Mycotoxins are secondary metabolites produced by microfungi that are capable of causing disease and death in humans and other animals. This work was aimed at investigation of influence of mouldy wheat contaminated by pathogenic fungi producing mycotoxins on metallothionein levels in hepatic tissue of rats. The rats were administrating feed mixtures with different contents of vitamins or naturally mouldy wheat for 28 days. It was found that the wheat contained deoxynivalenol (80 +/- 5 microg per kg of mouldy wheat), zearalenone (56 +/- 3 microg/kg), T2-toxin (20 +/- 2 microg/kg) and aflatoxins as a sum of B1, B2, G1 and G2 (3.9 +/- 0.2 microg/kg). Rats were fed diets containing 0, 33, 66 and 100% naturally moulded wheat. Control group 0, 33, 66 and 100% contained vitamins according to Nutrient Requirements of Rats (NRC). Other four groups (control group with vitamins, vit33, vit66 and vit100%) were fed on the same levels of mouldy wheat, also vitamins at levels 100% higher than the previous mixtures. We determined weight, feed conversion and performed dissection to observe pathological processes. Changes between control group and experimental groups exposed to influence of mouldy wheat and experimental groups supplemented by higher concentration of vitamins and mouldy wheat were not observed. Livers were sampled and did not demonstrate significant changes in morphology compared to control either. In the following experiments the levels of metallothionein as a marker of oxidative stress was determined. We observed a quite surprising trend in metallothionein levels in animals supplemented with increased concentration of vitamins. Its level enhanced with increasing content of mouldy wheat. It was possible to determine a statistically significant decline (p<0.05) between control group and groups of animals fed with 33, 66 and 100% mouldy wheat. It is likely that some mycotoxins presented in mouldy wheat are able to block the mechanism of metallothionein synthesis.