Hyphenated chromatographic techniques for structural characterization and determination of masked mycotoxins

Occurrence of modified mycotoxins in Latin America: an up-to-date review

The Latin America region has a considerable extent of varied climate conditions: from tropical, subtropical, and warm temperate to temperate. Among the surface territory, different agricultural products are produced, making them an important food source for human consumption. Fungal species commonly colonize those important agricultural products and often contaminate them with mycotoxins that have a major impact on health, welfare, and productivity. Nowadays, special attention is paid to modified mycotoxins, which are those that cannot be detected by conventional analytical methods. However, little data about their natural occurrence in food and feed is available, especially in Latin American countries, where, among all the countries in this region, only a few of them are working on this subject. Thus, the present review summarizes the published information available in order to determine the possible human exposure risk to these toxins.

Fungal and Toxin Contaminants in Cereal Grains and Flours: Systematic Review and Meta-Analysis

Cereal grains serve as the cornerstone of global nutrition, providing a significant portion of humanity's caloric requirements. However, the presence of fungal genera, such Fusarium, Penicillium, Aspergillus, and Alternaria, known for their mycotoxin-producing abilities, presents a significant threat to human health due to the adverse effects of these toxins. The primary objective of this study was to identify the predominant fungal contaminants in cereal grains utilized in breadmaking, as well as in flour and bread. Moreover, a systematic review, including meta-analysis, was conducted on the occurrence and levels of mycotoxins in wheat flour from the years 2013 to 2023. The genera most frequently reported were Fusarium, followed by Penicillium, Aspergillus, and Alternaria. Among the published reports, the majority focused on the analysis of Deoxynivalenol (DON), which garnered twice as many reports compared to those focusing on Aflatoxins, Zearalenone, and Ochratoxin A. The concentration of these toxins, in most cases determined by HPLC-MS/MS or HPLC coupled with a fluorescence detector (FLD), was occasionally observed to exceed the maximum limits established by national and/or international authorities. The prevalence of mycotoxins in flour samples from the European Union (EU) and China, as well as in foods intended for infants, exhibited a significant reduction compared to other commercial flours assessed by a meta-analysis investigation.

Matrix-associated mycotoxins in foods, cereals and feedstuffs: A review on occurrence, detection, transformation and future challenges

Matrix-associated mycotoxins that bind with macromolecular components through covalent or non-covalent interactions easily occur in various cereals, cereal-based products, and cereal-based feedstuff. They are "masked" by macro-components, causing the underestimation of total exposure risk of mycotoxins. Most of the current reports focus on the free and modified mycotoxins, while the matrix-associated forms are ignored but still can exert toxic effects after ingestion. In this paper, current researches and future prospects of matrix-associated mycotoxins are reviewed. Especially, a focus is set on the transformation of matrix-associated mycotoxins with their free forms during metabolism and food processing. Enzymes, temperature and pH levels during food processing can induce the interconversion of matrix-associated mycotoxins with free mycotoxins. Furthermore, the analytical methods targeted on matrix-associated mycotoxins are discussed. Due to the lack of efficient methods releasing the mycotoxins from matrix, the standard analytical methods has not developed so far. Also, we further analyzed the challenges of matrix-associated mycotoxins about variety, occurrence, toxicity and transformation, exposure assessment, which contributes to establish preventive measures to control their hazards for consumers. Overall, this overview is significant for perfecting risk assessment, as well as developing effective prevention and control actions to matrix-associated mycotoxins.

Rapid and sensitive UHPLC-MS/MS methods for dietary sample analysis of 43 mycotoxins in China total diet study

INTRODUCTION

Mycotoxins are toxic metabolites produced by fungi that commonly contaminate foods. As recommended by the World Health Organization, total diet study (TDS) is the most efficient and effective way to estimate the dietary intakes of certain chemical substances for general populations. It requires sensitive and reliable analytical methods applicable to a wide range of complex food matrices and ready-to-eat dishes.

OBJECTIVES

A novel strategy with high selectivity and sensitivity, incorporating three methods based on ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS), was designed for measuring 43 mycotoxins in dietary samples in a China TDS.

METHODS

The 43 mycotoxins were divided into 3 groups for analysis to achieve better performance. For each group, an UHPLC-MS/MS method was developed to determine the target compounds after clean-up by solid phase extraction. A total of 21 isotope internal standards were employed for accurate quantitation. Method validation in terms of linearity, selectivity, sensitivity, accuracy, and precision was performed for all the 43 mycotoxins in 12 complex food matrices.

RESULTS

The limits of detection (LODs) and limits of quantitation (LOQs) were 0.002-1 ng mL-1 and 0.006-3 ng mL-1, respectively. The method recoveries of the 43 mycotoxins spiked in 12 food categories were in the range of 60.3%-175.9% after internal standard correction, with relative standard deviations (RSDs) below 13.9%. For practical application, this method was utilized for 72 dietary samples collected from 6 provinces in the 6th China TDS. More than 80% of the samples were found contaminated by mycotoxins. DON, SMC, FB1, ZEN, BEA, ENNB1, and ENNB were most detected.

CONCLUSIONS

The proposed methods with high sensitivity, accuracy, and robustness provide powerful tools for multi-mycotoxin monitoring and dietary exposure assessment, allowing 43 mycotoxins, including some emerging mycotoxins, to be accurately investigated in a total diet study for the first time.

Mycotoxin Identification and In Silico Toxicity Assessment Prediction in Atlantic Salmon

The present study aimed to identify mycotoxins in edible tissues of Atlantic salmon (Salmo salar) using liquid chromatography coupled to hybrid quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS). After using a non-targeted screening approach and a home-made spectral library, 233 mycotoxins were analyzed. Moreover, the occurrence of mycotoxins in fish filets was evaluated, and their potential toxicity was predicted by in silico methods. According to the obtained results, forty mycotoxins were identified in analyzed salmon samples, the predominant mycotoxins being enniatins (also rugulosin and 17 ophiobolins), commonly found in cereals and their by-products. Thus, mycotoxin carry-over can occur from feed to organs and edible tissues of cultivated fish. Moreover, the toxicity of detected mycotoxins was predicted by the in silico webserver ProTox-II, highlighting that special attention must be paid to some less reported mycotoxins due to their toxic predicted properties.

Determination of deoxynivalenol and its major conjugates in cereals using an organic solvent-free extraction and IAC clean-up coupled in-line with HPLC-PCD-FLD

A method for the determination of deoxynivalenol (DON) and its major conjugates in cereals was developed including an immunoaffinity column (IAC) clean-up coupled in-line with high-performance liquid chromatography, post-column derivatisation and fluorescence detection. An IAC for DON with cross-reactivity to 15-AcDON, 3-AcDON and DON-3-G enabled this approach. The isolated analytes were introduced into the chromatographic system without aliquotation employing the hot water elution technique, resulting in the desired low LOQ values for monitoring these analytes in cereals. The absence of any organic solvent during sample preparation in combination with an in-line IAC clean-up renders the method simple, fast, and environmentally friendly. Special attention was paid to inherent IACs properties such as cross-reactivity, analytes' competition and capacity. The method was applied to determine DON and its major conjugates in barley, wheat and maize in the range of 10-1000 µg kg^-1 of DON, 10-300 µg kg^-1 of DON-3-G and 15-AcDON and 10-100 µg kg^-1 of 3-AcDON. The apparent recoveries varied from 87% to 110% (average of 98%) and the intermediate precision was below 13.5% RSD (except for DON-3-G in wheat). Fifteen maize, wheat and barley samples were analysed revealing levels of DON conjugates that accounted from 9% to 60% of the "total DON" content (m/m). In general, the frequency and the measured mass fractions decreased in the following order: DON>DON-3-G>15-AcDON>3-AcDON.

Assessment of Fumonisin B1 Concentrations in Wheat and Barley Products in the Punjab Region of Pakistan

ABSTRACT

A total of 133 samples of whole wheat and barley grains and wheat and barley flour collected from retail markets in the main cities of Punjab, Pakistan, were analyzed for the mycotoxin fumonisin B1 (FB1) using reverse phase high-performance liquid chromatography with fluorescence detection. Of these samples, 120 (90%) were positive for FB1, and 75 (63%) of the 120 positive samples had FB1 concentrations higher than the European Union maximum (200 μg/kg). The limit of detection was 4 μg/kg. The highest mean (±SD) concentration of FB1 was found in whole wheat samples, 980.5 ± 211.4 μg/kg. The calculated dietary intakes of FB1 from wheat and barley flours were 4,456 and 503.7 ng/g of body weight per day, respectively.

HIGHLIGHTS

Rapid and sensitive detection of mycotoxins by advanced and emerging analytical methods: A review

Quantification of mycotoxins in foodstuffs is extremely difficult as a limited amount of toxins are known to be presented in the food samples. Mycotoxins are secondary toxic metabolites, made primarily by fungal species, contaminating feeds and foods. Due to the presence in globally used grains, it is an unpreventable problem that causes various acute and chronic impacts on human and animal health. Over the previous few years, however, progress has been made in mycotoxin analysis studies. Easier techniques of sample cleanup and advanced chromatographic approaches have been developed, primarily high-performance liquid chromatography. Few extremely sophisticated and adaptable tools such as high-resolution mass spectrometry and gas chromatography-tandem MS/MS have become more important. In addition, Immunoassay, Advanced quantitative techniques are now globally accepted for mycotoxin analysis. Thus, this review summarizes these traditional and highly advance methods and their characteristics for evaluating mycotoxins.

Conversion of Deoxynivalenol-3-Glucoside to Deoxynivalenol during Chinese Steamed Bread Processing

We reported the conversion of deoxynivalenol-3-glucoside (D3G) to deoxynivalenol (DON) during Chinese steamed bread (CSB) processing by artificial D3G contamination. Meanwhile, the effects of enzymes in wheat flour and those produced from yeast, along with the two main components in wheat flour-wheat starch and wheat gluten-on the conversion profiles of D3G were evaluated. The results showed D3G could convert to DON during CSB processing, and the conversion began with dough making and decreased slightly after fermentation and steaming. However, there was no significant difference in three stages. When yeast was not added, or enzyme-deactivated wheat flour was used to simulate CSB process, and whether yeast was added or not, D3G conversion could be observed, and the conversion was significantly higher after dough making. Likewise, D3G converted to DON when wheat starch and wheat gluten were processed to CSB, and the conversion in wheat starch was higher.

Modified mycotoxins: An updated review on their formation, detection, occurrence, and toxic effects

Modified mycotoxins are metabolites that normally remain undetected during the testing for parent mycotoxin. These modified forms of mycotoxins can be produced by fungi or generated as part of the defense mechanism of the infected plant. In some cases, they are formed during food processing. The various processing steps greatly affect mycotoxin levels present in the final product (free and modified), although the results are still controversial regarding the increase or reduction of these levels, being strongly related to the type of process and the composition of the food in question. Evidence exists that some modified mycotoxins can be converted into the parent mycotoxin during digestion in humans and animals, potentially leading to adverse health effects. Some of these formed compounds can be even more toxic, in case they have higher bioaccessibility and bioavailability than the parent mycotoxin. The modified mycotoxins can occur simultaneously with the free mycotoxin, and, in some cases, the concentration of modified mycotoxins may exceed the level of free mycotoxin in processed foods. Even though toxicological data are scarce, the possibility of modified mycotoxin conversion to its free form may result in a potential risk to human and animal health. This review aims to update information on the formation, detection, occurrence, and toxic effects caused by modified mycotoxin.

Risks to human and animal health related to the presence of deoxynivalenol and its acetylated and modified forms in food and feed

Deoxynivalenol (DON) is a mycotoxin primarily produced by Fusarium fungi, occurring predominantly in cereal grains. Following the request of the European Commission, the CONTAM Panel assessed the risk to animal and human health related to DON, 3-acetyl-DON (3-Ac-DON), 15-acetyl-DON (15-Ac-DON) and DON-3-glucoside in food and feed. A total of 27,537, 13,892, 7,270 and 2,266 analytical data for DON, 3-Ac-DON, 15-Ac-DON and DON-3-glucoside, respectively, in food, feed and unprocessed grains collected from 2007 to 2014 were used. For human exposure, grains and grain-based products were main sources, whereas in farm and companion animals, cereal grains, cereal by-products and forage maize contributed most. DON is rapidly absorbed, distributed, and excreted. Since 3-Ac-DON and 15-Ac-DON are largely deacetylated and DON-3-glucoside cleaved in the intestines the same toxic effects as DON can be expected. The TDI of 1 μg/kg bw per day, that was established for DON based on reduced body weight gain in mice, was therefore used as a group-TDI for the sum of DON, 3-Ac-DON, 15-Ac-DON and DON-3-glucoside. In order to assess acute human health risk, epidemiological data from mycotoxicoses were assessed and a group-ARfD of 8 μg/kg bw per eating occasion was calculated. Estimates of acute dietary exposures were below this dose and did not raise a health concern in humans. The estimated mean chronic dietary exposure was above the group-TDI in infants, toddlers and other children, and at high exposure also in adolescents and adults, indicating a potential health concern. Based on estimated mean dietary concentrations in ruminants, poultry, rabbits, dogs and cats, most farmed fish species and horses, adverse effects are not expected. At the high dietary concentrations, there is a potential risk for chronic adverse effects in pigs and fish and for acute adverse effects in cats and farmed mink.

A sensitive and validated immunomagnetic-bead based enzyme-linked immunosorbent assay for analyzing total T-2 (free and modified) toxins in shrimp tissues

Accurate analyses of total T-2 (free and modified) in aquatic organisms including shrimp are important as the hazard caused by T-2 has been caught increasing attention. Therefore, acurate analysis of free T-2 especially of modified T-2 in shrimp tissues is important. A rapid, sensitive, and validated method for quantitative determination of free T-2 and modified T-2 toxin was developed using immunomagnetic-bead based enzyme-linked immunosorbent assay (IMB-ELISA). Super paramagnetic particles with a carboxyl group activated by an ester method coupled with envelope antigen 3- acetylneosolaniol- hemisuccinate - ovalbumin (3-Ac-NEOS-HS-OVA) was used to form immunomagnetic beads which could bind to T-2 skeletal structure antibodies. The conditions for magnetic bead coating of T-2 skeletal structure antibodies, and the concentrations of the polyclonal antibody and HRP-labeled goat anti-rabbit antibody were optimized. A good linear relationship with T-2 concentrations ranging from 5-75ng/mL (R² =0.9965) was observed. The detection limit of different shrimp tissues of the IMB-ELISA ranged from 2.53 to 3.20ng/mL. And the IC₅₀ was 63ng/mL. The recovery varied from 86% to 99% with a standard deviation of 2.8-5.8%. The application of this method to study the distribution in tissues showed that the total T-2 concentration in hepatopancreas was 26.7µg/kg > blood > head > muscle in the highest dose group of 12.2mg/kg. Our research showed a combination of ELISA and immunomagnetic bead technology provide a new, convenient approach to significantly improve the accuracy and sensitivity of total T-2 measurement in shrimp tissues.

Individual and Combined Cytotoxic Effects of Co-Occurring Deoxynivalenol Family Mycotoxins on Human Gastric Epithelial Cells

Mycotoxin contamination is a significant health concern for human beings, but health risk assessments are usually based on one single mycotoxin, which might neglect the additive or competitive interactions between co-occurring mycotoxins. In this study, we assessed the individual or combined toxicological effects to multiple deoxynivalenol-family mycotoxins, namely deoxynivalenol (DON), Nivalenol (NIV), and their acetyl derivatives of 3-acetyldeoxynivalenol (3-ADON), 15-acetyldeoxynivalenol (15-ADON), deoxynivalenol-3-glucoside (D3G), and Fusarenon-X (FX) based on the human gastric epithelial (GES-1) cells. GES-1 cells were treated at different concentrations over 24 h and cell viability was measured by a cell counting kit (CCK8). The results show that D3G has no toxicity and 3-ADON is less potent in reducing cell viability compared to DON, whereas 15-ADON and FX appear to be slightly less potent than their parent compounds of DON and NIV on GES-1 cells. In general, the toxic ability of individual mycotoxins was shown as 3-ADON << 15-ADON < DON < FX < NIV, in an increasing order. All mixtures caused a dose-dependent decline of cell viability and the interactions analysis of binary combinations were assessed using the combination index (CI)-isobologram method. For the interaction types of mycotoxins mixtures, the synergistic cytotoxicity of DON + 15-ADON, DON + NIV, and DON + FX at low and/or moderate inhibitory concentration levels (IC10–IC70, IC10–IC80, and IC10–IC40, respectively) were observed. FX + NIV resulted in almost completely synergistic cytotoxicity, whereas 15-ADON + NIV and 15-ADON + FX presented almost entirely antagonistic cytotoxicity on the GES-1 cell model. These results suggest that the simultaneous presence of low-dose type B trichothecenes in dietary food may be more or less toxic than the prediction based on individual mycotoxins.

Recent Advances and Future Challenges in Modified Mycotoxin Analysis: Why HRMS Has Become a Key Instrument in Food Contaminant Research

Mycotoxins are secondary metabolites produced by pathogenic fungi in crops worldwide. These compounds can undergo modification in plants, leading to the formation of a large number of possible modified forms, whose toxicological relevance and occurrence in food and feed is still largely unexplored. The analysis of modified mycotoxins by liquid chromatography-mass spectrometry remains a challenge because of their chemical diversity, the large number of isomeric forms, and the lack of analytical standards. Here, the potential benefits of high-resolution and ion mobility mass spectrometry as a tool for separation and structure confirmation of modified mycotoxins have been investigated/reviewed.

Cross-reactivity features of deoxynivalenol (DON)-targeted immunoaffinity columns aiming to achieve simultaneous analysis of DON and major conjugates in cereal samples

Immunoaffinity columns (IACs) are a well-established tool in the determination of regulated mycotoxins in food and feed commodities. However, they also have the potential to become attractive pre-concentration and clean-up materials for the determination of masked (also called modified) mycotoxins, which have been recognised as important contributors to the toxicological hazard deriving from fungal spoilage of goods. However, the information available in the literature concerning the cross-reactivity of DON-IACs against the major conjugates (DON-3-G, 15-AcDON and 3-AcDON) is incomplete and often contradictory. We have carried out a detailed characterisation of the cross-reactivity of the four main IACs brands against DON and its conjugates as well as an assessment of the competition among the analytes. Only one IAC enabled the simultaneous analysis of all relevant DON forms while two missed 15-AcDON and the fourth one missed DON-3-G and 3-AcDON. In the case of the multivalent IAC, the analytes modified at the C-3 position compete for the antibody binding with preference for 3-AcDON (less spatially hindered) while DON-3-G has the more-hindered access to the active sites. Taking into consideration the levels of DON conjugates existing in real samples, the cross-reactivity of one DON-IAC allows a quantitative analysis of all of these analytes. Important but rather neglected aspects such as the continuous supply of IACs with identical characteristics, and of columns which are strictly blank, are also addressed in this paper.

Natural Co-Occurrence of Mycotoxins in Foods and Feeds and Their in vitro Combined Toxicological Effects

Some foods and feeds are often contaminated by numerous mycotoxins, but most studies have focused on the occurrence and toxicology of a single mycotoxin. Regulations throughout the world do not consider the combined effects of mycotoxins. However, several surveys have reported the natural co-occurrence of mycotoxins from all over the world. Most of the published data has concerned the major mycotoxins aflatoxins (AFs), ochratoxin A (OTA), zearalenone (ZEA), fumonisins (FUM) and trichothecenes (TCTs), especially deoxynivalenol (DON). Concerning cereals and derived cereal product samples, among the 127 mycotoxin combinations described in the literature, AFs+FUM, DON+ZEA, AFs+OTA, and FUM+ZEA are the most observed. However, only a few studies specified the number of co-occurring mycotoxins with the percentage of the co-contaminated samples, as well as the main combinations found. Studies of mycotoxin combination toxicity showed antagonist, additive or synergic effects depending on the tested species, cell model or mixture, and were not necessarily time- or dose-dependent. This review summarizes the findings on mycotoxins and their co-occurrence in various foods and feeds from all over the world as well as in vitro experimental data on their combined toxicity.

Analytical methods for determination of mycotoxins: An update (2009-2014)

Mycotoxins are a problematic and toxic group of small organic molecules that are produced as secondary metabolites by several fungal species that colonise crops. They lead to contamination at both the field and postharvest stages of food production with a considerable range of foodstuffs affected, from coffee and cereals, to dried fruit and spices. With wide ranging structural diversity of mycotoxins, severe toxic effects caused by these molecules and their high chemical stability the requirement for robust and effective detection methods is clear. This paper builds on our previous review and summarises the most recent advances in this field, in the years 2009-2014 inclusive. This review summarises traditional methods such as chromatographic and immunochemical techniques, as well as newer approaches such as biosensors, and optical techniques which are becoming more prevalent. A section on sampling and sample treatment has been prepared to highlight the importance of this step in the analytical methods. We close with a look at emerging technologies that will bring effective and rapid analysis out of the laboratory and into the field.

Simultaneous determination of major type A and B trichothecenes, zearalenone and certain modified metabolites in Finnish cereal grains with a novel liquid chromatography-tandem mass spectrometric method

A reliable and sensitive liquid chromatography-tandem mass spectrometric method was developed for the simultaneous quantitative determination in cereals of the Fusarium mycotoxins HT-2 toxin, T-2 toxin, deoxynivalenol, nivalenol and zearalenone, as well as the modified metabolites 3-acetyl-deoxynivalenol, α-zearalenol, β-zearalenol, deoxynivalenol-3-glucoside, HT-2-3-glucoside, nivalenol-3-glucoside, zearalenone-14-glucoside, zearalenone-14-sulphate, zearalenone-16-glucoside, α-zearalenol-14-glucoside and β-zearalenol-14-glucoside. The ‘dilute and shoot’ approach was used for sample preparation after extraction with acetonitrile:water:acetic acid (79:20:1, v/v/v). Separation was carried out using reversed-phase liquid chromatography, and detection was performed using tandem mass spectrometry in the selected reaction monitoring mode. The method was in-house validated according to performance characteristics, established in Commission Regulation EC No 401/2006 and Commission Decision EC No 657/2002, prior to its application in a nationwide survey for the analysis of barley, oat and wheat samples (n = 95) harvested in Finland during 2013. Deoxynivalenol and its glucosylated form were the most abundant of the analytes, being detected in 93 and 81 % of the samples, respectively. Concentrations of deoxynivalenol were unusually high in 2013, especially in oats, with some cases exceeding the maximum legislative limits for unprocessed oats placed on the market for first-stage processing. All modified mycotoxins analysed were detected, and the natural occurrence of some of these compounds (e.g. zearalenone-16-glucoside and nivalenol-3-glucoside) in barley, oats and/or wheat was documented for the first time.

Occurrence and stability of masked fumonisins in corn silage samples

Corn plants contaminated with Fusarium verticilloides were harvested at two dates and ensiled in laboratory silos. The stability of Fumonisins B1 and B2 (FB1, FB2) was studied and the effects of inoculant use (Lactobacillus buchneri) and of the ensiling time were assessed. The occurrence of masked fumonisins was also investigated. After the extraction of the free forms (FB1, FB2), the residue was subjected to an alkaline hydrolysis resulting in the release of derivates subsequently detected by LC-HESI-MS/MS. The ensiling time has shown to be a significant factor for the evolution of free FB1 and FB2 at the 2nd harvest date. Moreover, the use of inoculant had a significant effect on the stability of hidden and total FB1 at the two harvest dates. Samples previously ensiled and exposed to aerobic conditions for 7days have shown higher fumonisin levels than those not exposed to air. Our results showed that 65% and 39% of the total FB1 and FB2 contents in silage were due to hidden fumonisins.

Rapid multiple immunoenzyme assay of mycotoxins

Mycotoxins are low molecular weight fungal metabolites that pose a threat as toxic contaminants of food products, thereby necessitating their effective monitoring and control. Microplate ELISA can be used for this purpose, but this method is characteristically time consuming, with a duration extending to several hours. This report proposes a variant of the ELISA method for the detection and quantification of three mycotoxins, ochratoxin A, aflatoxin B1 and zearalenone, in the kinetic regime. The main requirement for the proposed kinetic protocol was to provide a rapid method that combined sensitivity and accuracy. The use of biotin with an extended spacer together with a streptavidin-polyperoxidase conjugate provided high signal levels, despite these interactions occurring under non-equilibrium conditions. Duration of the individual mycotoxin assays was 20 min, whereas the analysis of all three mycotoxins in parallel reached a maximum duration of 25 min. Recovery of at least 95% mycotoxins in water-organic extracts was shown. The developed assays were successfully validated using poultry processing products and corn samples spiked with known quantities of mycotoxins. The detection limits for aflatoxin B1, ochratoxin A and zearalenone in these substances were 0.24, 1.2 and 3 ng/g, respectively.

Proposal of a comprehensive definition of modified and other forms of mycotoxins including "masked" mycotoxins

As the term “masked mycotoxins” encompasses only conjugated mycotoxins generated by plants and no other possible forms of mycotoxins and their modifications, we hereby propose for all these forms a systematic definition consisting of four hierarchic levels. The highest level differentiates the free and unmodified forms of mycotoxins from those being matrix-associated and from those being modified in their chemical structure. The following lower levels further differentiate, in particular, “modified mycotoxins” into “biologically modified” and “chemically modified” with all variations of metabolites of the former and dividing the latter into “thermally formed” and “non-thermally formed” ones. To harmonize future scientific wording and subsequent legislation, we suggest that the term “modified mycotoxins” should be used in the future and the term “masked mycotoxins” to be kept for the fraction of biologically modified mycotoxins that were conjugated by plants.

Developments in mycotoxin analysis: an update for 2012-2013

This review highlights developments in mycotoxin analysis and sampling over a period between mid-2012 and mid-2013. It covers the major mycotoxins: aflatoxins, Alternaria toxins, ergot alkaloids, fumonisins, ochratoxins, patulin, trichothecenes and zearalenone. A wide range of analytical methods for mycotoxin determination in food and feed were developed last year, in particular immunochemical methods and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS)-based methods. After a section on sampling and sample preparation, due to the rapid spread and developments in the field of LC-MS/MS multimycotoxin methods, a separate section has been devoted to this area of research. It is followed by a section on mycotoxins in botanicals and spices, before continuing with the format of previous reviews in this series with dedicated sections on method developments for the individual mycotoxins.

Detached leaf in vitro model for masked mycotoxin biosynthesis and subsequent analysis of unknown conjugates

The manuscript details the development of an in vitro model plant system using detached leaves because there is a need for biosynthetic methods for the production and isolation of masked mycotoxins. This detached leaf in vitro model was firstly applied to deoxynivalenol with satisfying results. The biosynthesis of deoxynivalenol-3-glucoside was confirmed using its respective commercially available reference standard. Secondly, the detached leaf in vitro model was applied to T-2 toxin. Mono- and tri-glucoside derivatives of T-2 toxin and HT-2 toxin, T-2-(3)-glucoside, T-2-(3)-triglucoside and HT-2-(3)-glucoside were identified and characterised using Orbitrap high-resolution mass spectrometry. This is the first report on a triglucoside of T-2 toxin. The discovery of new masked forms implies the importance of the development of analytical methods for their detection, the constitution of toxicity studies, and proving the relevance of their presence in the food and feed chain.

Identification of Alternaria alternata mycotoxins by LC-SPE-NMR and their cytotoxic effects to soybean (Glycine max) cell suspension culture

This present work describes the application of liquid chromatography-solid phase extraction-nuclear magnetic resonance spectroscopy to analyse Alternaria alternata crude extracts. Altenusin (1), alternariol (2), 3'-hydroxyalternariol monomethyl ether (3), and alternariol monomethyl ether (4), were separated and identified. High-resolution mass spectrometry confirmed the proposed structures. The cytotoxic effects of these compounds towards plants were determined using soybean (Glycine max) cell cultures as a model. EC(50) values which range from 0.11 (± 0.02) to 4.69 (± 0.47) μM showed the high cytotoxicity of these compounds.

Developments in mycotoxin analysis: an update for 2011-2012

This review highlights developments in mycotoxin analysis and sampling over a period between mid-2011 and mid- 2012. It covers the major mycotoxins aflatoxins, Alternaria toxins, ergot alkaloids, fumonisins, ochratoxin, patulin, trichothecenes, and zearalenone. A section on mycotoxins in botanicals and spices is also included. Methods for mycotoxin determination continue to be developed using a wide range of analytical systems ranging from rapid immunochemical-based methods to the latest advances in mass spectrometry. This review follows the format of previous reviews in this series (i.e. sections on individual mycotoxins), but due to the rapid spread and developments in the field of multimycotoxin methods by liquid chromatography-tandem mass spectrometry, a separate section has been devoted to advances in this area of research.

Masked mycotoxins: a review

The aim of this review is to give a comprehensive overview of the current knowledge on plant metabolites of mycotoxins, also called masked mycotoxins. Mycotoxins are secondary fungal metabolites, toxic to human and animals. Toxigenic fungi often grow on edible plants, thus contaminating food and feed. Plants, as living organisms, can alter the chemical structure of mycotoxins as part of their defence against xenobiotics. The extractable conjugated or non-extractable bound mycotoxins formed remain present in the plant tissue but are currently neither routinely screened for in food nor regulated by legislation, thus they may be considered masked. Fusarium mycotoxins (deoxynivalenol, zearalenone, fumonisins, nivalenol, fusarenon-X, T-2 toxin, HT-2 toxin, fusaric acid) are prone to metabolisation or binding by plants, but transformation of other mycotoxins by plants (ochratoxin A, patulin, destruxins) has also been described. Toxicological data are scarce, but several studies highlight the potential threat to consumer safety from these substances. In particular, the possible hydrolysis of masked mycotoxins back to their toxic parents during mammalian digestion raises concerns. Dedicated chapters of this article address plant metabolism as well as the occurrence of masked mycotoxins in food, analytical aspects for their determination, toxicology and their impact on stakeholders.