Extracting fumonisins from maize: efficiency of different extraction solvents in multi-mycotoxin analytics

An update on genotoxic and epigenetic studies of fumonisin B1

Fumonisins (FBs), a widespread group of mycotoxins produced by Fusarium spp., are natural contaminants in cereals and foodstuffs. Fumonisin B1 (FB1) is the most toxic and prevalent mycotoxin of this group, and it has been reported that FB1 accounts for 70-80% of FBs produced by the mycotoxigenic strains. The mode of action of FB1 depends on the structural similarity with sphinganine/sphingosine N-acyltransferase. This fact causes an accumulation of sphingoid bases and blocks the sphingolipid biosynthesis or the function of sphingolipids. Diverse toxic effects and diseases such as hepatocarcinogenicity, hepatotoxicity, nephrotoxicity, and cytotoxicity have been reported, and diseases like leukoencephalomalacia in horses and pulmonary oedema in horses and swine have been described. In humans, FBs have been associated with oesophageal cancer, liver cancer, neural tube defects, and infantile growth delay. However, despite the International Agency for Research on Cancer designated FB1 as a possibly carcinogenic to humans, its genotoxicity and epigenetic properties have not been clearly elucidated. This review aims to summarise the progress in research about the genotoxic and epigenetics effects of FB1.

Long Term Monitoring (2014⁻2018) of Multi-Mycotoxins in South African Commercial Maize and Wheat with a Locally Developed and Validated LC-MS/MS Method

Mycotoxins occur worldwide in the major grains, and producers, traders and processors are all challenged to prevent serious health problems for consumers. The challenges originate with pre-harvest fungi infections in the grain fields, increased contamination during improper storage and, finally, the mycotoxin accumulation in commercial food and feed products. Little is known about the multi-mycotoxin occurrence in maize and wheat commercially produced in South Africa. This is the first comprehensive study that reports on the multi-mycotoxin occurrence in South African produced maize and wheat crops after harvest, over four production seasons, in all the production regions of the country. The study was made possible with the development of a fit-for-purpose, cost-effective LC-MS/MS multi-mycotoxin method, validated for 13 “regulated” mycotoxins. A low mycotoxin risk was found in South African produced wheat, with only deoxynivalenol (DON) in 12.5% of the 160 samples at levels well below the 2000 µg/kg South African (SA) regulatory level. It was concluded that aflatoxin B₁ (AFB₁) is seldom present in South African produced commercial maize. The concentrations, regional variation and seasonal trends of deoxynivalenol and fumonisins, the two most prevalent mycotoxins, and of zearalenone (ZON), are reported for white and yellow maize in all the production provinces, based on the analytical results of 1400 maize samples. A threefold to eightfold increase in deoxynivalenol mean concentrations in white maize was observed in the main production regions in the fourth season, with 8.9% samples above 2000 µg/kg. A strong correlation was found between higher deoxynivalenol concentrations and the presence of 15-acetyl-deoxynivalenol (15-ADON). The mean fumonisin concentrations were well below the 4000 µg/kg South African regulatory value. A possible shift in the incidence and severity of mycotoxigenic Fusarium spp. in the provinces must be investigated. The variations and trends highlight the importance of a continuous monitoring of multi-mycotoxins in South Africa along the grain value chain.

Visual Non-Instrumental On-Site Detection of Fumonisin B₁, B₂, and B₃ in Cereal Samples Using a Clean-Up Combined with Gel-Based Immunoaffinity Test Column Assay

A visual immunoaffinity test column (IATC) assay was developed to detect fumonisins in cereal samples for spot tests without the need for special instruments. The developed IATC assay had equivalent recognition capability for fumonisin B₁ (FB₁), fumonisin B₂ (FB₂), or fumonisin B₃ (FB₃), and exhibited no cross-reactivity with aflatoxin B₁, ochratoxin A, zearalenone, or the T-2 toxin. The sample pretreatment was accomplished more rapidly and with greater ease, the entire assay procedure was completed in approximately 10 min, including sample pretreatment and testing. The limits of detection (LODs) of the IATC assay to detect fumonisins in the maize, barley, oat, and millet samples were 20 μg kg−1. The results of the spiked maize, barley, oat, and millet and real maize samples by the IATC assay agreed well with the results obtained by the commercial fumonisin enzyme-linked immunosorbent assay (ELISA) test kit and liquid chromatography-tandem mass spectrometry (LC-MS/MS), respectively. The developed IATC assay can serve as a useful screening tool for the rapid, qualitative, and semi-quantitative detection of the total content of fumonisins (sum of FB₁, FB₂, and FB₃) in cereal samples on-site.

A Collaborative Study: Determination of Mycotoxins in Corn, Peanut Butter, and Wheat Flour Using Stable Isotope Dilution Assay (SIDA) and Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

A collaborative study was conducted to evaluate stable isotope dilution assay (SIDA) and LC-MS/MS for the simultaneous determination of aflatoxins B₁, B₂, G₁, and G₂; deoxynivalenol; fumonisins B₁, B₂, and B₃; ochratoxin A; HT-2 toxin; T-2 toxin; and zearalenone in foods. Samples were fortified with 12 ¹³C uniformly labeled mycotoxins (¹³C-IS) corresponding to the native mycotoxins and extracted with acetonitrile/water (50:50 v/v), followed by centrifugation, filtration, and LC-MS/MS analysis. In addition to certified reference materials, the six participating laboratories analyzed corn, peanut butter, and wheat flour fortified with the 12 mycotoxins at concentrations ranging from 1.0 to 1000 ng/g. Using their available LC-MS/MS platform, each laboratory developed in-house instrumental conditions for analysis. The majority of recoveries ranged from 80 to 120% with relative standard derivations (RSDs) <20%. Greater than 90% of the average recoveries of the participating laboratories were in the range of 90-110%, with repeatability RSD_r (within laboratory) < 10% and reproducibility RSD_R (among laboratory) < 15%. All Z scores of the results of certified reference materials were between -2 and 2. Using ¹³C-IS eliminated the need for matrix-matched calibration standards for quantitation, simplified sample preparation, and achieved simultaneous identification and quantitation of multiple mycotoxins in a simple LC-MS/MS procedure.

A novel recombinant cell fluorescence biosensor based on toxicity of pathway for rapid and simple evaluation of DON and ZEN

During an exposure, humans and animals are most often exposed to a mixture rather than individual mycotoxins. In this study, a Human Embryonic Kidney 293 cell (HEK-293) fluorescence sensor was developed to detect and evaluate mycotoxins, deoxynivalenol (DON) and zearalenone (ZEN) compounds, produced by Fusarium culmorum that are common food contaminants. TRE-copGFP (green fluorescent protein) and ERE-TagRFP (red fluorescent protein) plasmids were constructed and cotransfected into HEK-293 cells through a highly efficient, lipid-mediated, DNA-transfection procedure. Results show that fluorescence intensity was proportional to DON and ZEN concentrations, ranging from 2 to 40 ng/mL and 10 to 100 ng/mL respectively, with a detection limit of 0.75 ng/mL and 3.2 ng/mL respectively. The EC50 of DON and ZEN are 30.13 ng/mL and 76.63 ng/mL respectively. Additionally, ZEN may have a synergistic effect on enhancing AP-1 activity of the toxicity pathway of DON. These data indicate the high sensitivity and effectiveness of our biosensor system in the evaluation of the combined toxicity of ZEN, DON and their derivatives. In addition, this approach is suitable for an early warning method for the detection of ZEN and DON family mycotoxins contamination without higher-priced, conventional analytical chemistry methods.

Fumonisins: oxidative stress-mediated toxicity and metabolism in vivo and in vitro

Fumonisins (FBs) are widespread Fusarium toxins commonly found as corn contaminants. FBs could cause a variety of diseases in animals and humans, such as hepatotoxic, nephrotoxic, hepatocarcinogenic and cytotoxic effects in mammals. To date, almost no review has addressed the toxicity of FBs in relation to oxidative stress and their metabolism. The focus of this article is primarily intended to summarize the progress in research associated with oxidative stress as a plausible mechanism for FB-induced toxicity as well as the metabolism. The present review showed that studies have been carried out over the last three decades to elucidate the production of reactive oxygen species (ROS) and oxidative stress as a result of FBs treatment and have correlated them with various types of FBs toxicity, indicating that oxidative stress plays critical roles in the toxicity of FBs. The major metabolic pathways of FBs are hydrolysis, acylation and transamination. Ceramide synthase, carboxylesterase FumD and aminotransferase FumI could degrade FB1 and FB2. The cecal microbiota of pigs and alkaline processing such as nixtamalization can also transform FB1 into metabolites. Most of the metabolites of FB1 were less toxic than FB1, except its partial (pHFB1) metabolites. Further understanding of the role of oxidative stress in FB-induced toxicity will throw new light on the use of antioxidants, scavengers of ROS, as well as on the blind spots of metabolism and the metabolizing enzymes of FBs. The present review might contribute to reveal the toxicity of FBs and help to protect against their oxidative damage.

Determining mycotoxins in baby foods and animal feeds using stable isotope dilution and liquid chromatography tandem mass spectrometry

We developed a stable isotope dilution assay with liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine multiple mycotoxins in baby foods and animal feeds. Samples were fortified with [(13)C]-uniformly labeled mycotoxins as internal standards ([(13)C]-IS) and prepared by solvent extraction (50% acetonitrile in water) and filtration, followed by LC-MS/MS analysis. Mycotoxins in each sample were quantitated with the corresponding [(13)C]-IS. In general, recoveries of aflatoxins (2-100 ng/g), deoxynivalenol, fumonisins (50-2000 ng/g), ochratoxin A (20-1000 ng/kg), T-2 toxin, and zearalenone (40-2000 ng/g) in tested matrices (grain/rice/oatmeal-based formula, animal feed, dry cat/dog food) ranged from 70 to 120% with relative standard deviations (RSDs) <20%. The method provides sufficient selectivity, sensitivity, accuracy, and reproducibility to screen for aflatoxins at ng/g concentrations and deoxynivalenol and fumonisins at low μg/g concentrations in baby foods and animal feeds, without using conventional standard addition or matrix-matched calibration standards to correct for matrix effects.

Immunoaffinity clean-up of mycotoxins with organic solvent-free elution

A novel immunoaffinity (IA) clean-up procedure for the isolation of mycotoxins from maize extracts is described. Commonly, mycotoxins are eluted with organic solvents from IA columns after isolation. The new procedure uses water at 70 °C as alternative. The resulting eluate is suitable for direct and complete injection onto a reversed-phase liquid-chromatography column. Evaporation, reconstitution or dilution are not required. The procedure has been tested for a variety of mycotoxins, including deoxynivalenol (DON) zearalenone, T-2 and HT-2 toxins, aflatoxins and ochratoxin A in an array of different matrices. The example of DON in maize is discussed in more detail and evaluated for repeatability (5%, n=10) and recovery (95%, n=10).

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.