[Occurrence and exposure assessment of fumonisins from grains and grain products in Zhejiang Province in 2018-2019].

OBJECTIVE: To monitor fumonisins(FBs) in grains and grain products in Zhejiang and assess the exposure risks of FBs to local residents. METHODS: Liquid chromatography coupled with tandem mass spectrometry method was used to determine the occurrence of FBs in rice, millet, dried noodles, instant noodles, and maize grains, and food frequency questionnaires were used to collect the food consumption data of Zhejiang population. Then, the simple probability distribution model was used to assess the exposure risk. RESULTS: The levels of FBs in rice, millet, dried noodles and instant noodles were relatively low. The occurrence of FB_1, FB_2 and FB_3 in these foods was 0-23.7%, 0-16.7% and 0-5.4%, respectively, and the mean levels were not detected(ND)-22.36, ND-20.63 and ND-7.19 µg/kg correspondingly. However, the levels of FBs in maize grains were relatively high. The occurrence of FB_1, FB_2, and FB_3 in maize grains was 100%, 93.6% and 90.3%, respectively, and the mean levels were 638.99, 103.54 and 59.69 µg/kg correspondingly. In 12.9% of the maize grain samples, the levels of FBs were higher than the standard reference. The residents were at low exposure risk overall. The mean estimated daily intake(EDI) of FBs was far lower than the provisional maximum tolerable daily intake of 2 µg/(kg·BW·d). However, 0.30% of the residents were at high risk. Among people of different ages, the mean EDI of children, adults, and elderly were 0.43, 0.28 and 0.29 µg/(kg·BW·d) respectively, and children were in the highest exposure levels of FBs. Among the tested five foodstuffs, rice and maize grains were the main sources of FBs exposure. CONCLUSION: Except for maize grains, the levels of FBs in grains and grain products were relatively low, and Zhejiang residents were at low FBs exposure risk generally.

Effect of Baking Conditions and Glucose Addition on the Changes and Transformations between Fumonisins and their Covert Forms during Corn Crisp Processing.

This study investigated the impact of baking factors on fumonisin B (FB) levels in corn crisps using ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The results indicated that both free and total FBs decreased with an increase in baking time and temperature, while glucose addition facilitated this reduction. Total FBs reached the lowest value of 109.69 ng/g after 50 min of baking. Conversely, covert FBs increased with baking time but decreased with glucose addition at high temperatures. Additionally, the highest levels of hydrolyzed FBs (HFBs), N-(carboxymethyl) FB1, and N-(deoxy-d-fructos-1-yl) FB1 occurred 20 min before decomposing and were detected in corn crisps baked at 160 °C. Glucose addition accelerated the transformation between free and covert FBs. Furthermore, the inhibition of NCM FB1 accumulation was accompanied by the promotion of NDF FB1 accumulation during corn crisp processing. These findings provide insights into the effect of baking factors on FBs and suggest strategies for reducing FB contamination in corn crisps.

Z-scheme Cu2MoS4/CdS/In2S3 nanocages heterojunctions-based PEC aptasensor for ultrasensitive assay of fumonisin B1 via signal amplification with hollow PtPd-CoSnO3 nanozyme.

Fumonisin B1 (FB1), the most prevalent and highest toxicity mycotoxins among fumonisins family, poses threats to human especially children and infants even at a trace level. Therefore, its facile and sensitive detection is of importance. Herein, Z-scheme Cu2MoS4/CdS/In2S3 nanocage-like heterojunctions (labeled Cu2MoS4/CdS/In2S3) were synthesized, whose photoelectrochemical (PEC) property and electron transfer mechanism were strictly investigated. The Cu2MoS4/CdS/In2S3 behaved as photoactive substrate for building a PEC sensing platform for detection of FB1, integrated with PtPd alloy modified hollow CoSnO3 nanoboxes (labeled PtPd-CoSnO3) nanozyme. By virtue of the stronger affinity between the target FB1 and its aptamer (FB1-Apt), the photocurrent was recovered by releasing the CoSnO3-PtPd3 modified FB1-Apt (FB1-Apt/PtPd-CoSnO3) from the photoanode, which can terminate the catalytic precipitation reaction for its peroxidase-like property. The resultant PEC aptasensor exhibited a wider dynamic linear range from 1 × 10-4 to 1 × 102 ng mL-1 with a lower limit of detection (0.0723 pg mL-1). Thus, this research provides a feasible PEC sensing platform for routine analysis of other mycotoxins in practice.

The natural occurrence, toxicity mechanisms and management strategies of Fumonisin B1：A review.

Fumonisin B1 (FB1) contaminates various crops, causing huge losses to agriculture and livestock worldwide. This review summarizes the occurrence regularity, toxicity, toxic mechanisms and management strategies of FB1. Specifically, FB1 contamination is particularly serious in developing countries, humid and hot regions. FB1 exposure can produce different toxic effects on the nervous system, respiratory system, digestive system and reproductive system. Furthermore, FB1 can also cause systemic immunotoxicity. The mechanism of toxic effects of FB1 is to interfere with the normal pathway of sphingolipid de novo biosynthesis by acting as a competitive inhibitor of ceramide synthase. Meanwhile, the toxic products of sphingolipid metabolic disorders can cause oxidative stress and apoptosis. FB1 also often causes feed contamination by mixing with other mycotoxins, and then exerts combined toxicity. For detection, lateral flow dipstick technology and enzyme linked immunosorbent assay are widely used in the detection of FB1 in commercial feeds, while mainstream detection methods such as high performance liquid chromatography and liquid chromatography-mass spectrometry are widely used in the laboratory theoretical study of FB1. For purification means of FB1, some natural plant extracts (such as Zingiber officinale and Litsea Cubeba essential oil) and their active compounds have been proved to inhibit the toxic effects of FB1 and protect livestock due to their antifungal and antioxidant effects. Natural plant extract has the advantages of high efficiency, low cost and no contamination residue. This review can provide information for comprehensive understanding of FB1, and provide reference for formulating reasonable treatment and management strategies in livestock production.

FumDSB can alleviate the inflammatory response induced by fumonisin B1 in growing pigs.

Fumonisin B1 (FB1) has the highest natural contamination rate among all fumonisin analogs and can inhibit food intake and weight gain of pigs. Under laboratory conditions, carboxylesterase FumDSB has a high FB1 degradation rate and excellent pH and thermal stability. The present study sought to estimate the effects of FumDSB on growing pigs from the perspective of a brain-intestinal axis. Twenty-four growing pigs of similar weight were divided into Control, FB1 (5 mg FB1/kg feed), and FumDSB (5 mg FB1/kg and 0.1% FumDSB in the feed) groups. After 42 days of feeding, hypothalamus and jejunum samples were collected for quantitative real-time fluorescence, western blotting, and immunohistochemistry. The results showed that FB1 consumption can destruct the tissue structure of hypothalamus and jejunum, affect the expression and distribution of several appetite-related neuropeptides and inflammatory cytokines, thereby inducing neuroinflammatory responses and affecting food intake and weight gain. However, these anorexia effects and inflammatory responses are alleviated when FumDSB is added to the feed. In short, FumDSB can alleviate the inflammatory response induced by FB1 in growing pigs.

Use of Mustard Extracts Fermented by Lactic Acid Bacteria to Mitigate the Production of Fumonisin B1 and B2 by Fusarium verticillioides in Corn Ears.

Corn (Zea mays) is a worldwide crop subjected to infection by toxigenic fungi such as Fusarium verticillioides during the pre-harvest stage. Fusarium contamination can lead to the synthesis of highly toxic mycotoxins, such as Fumonisin B1 (FB1) and Fumonisin B2 (FB2), which compromises human and animal health. The work aimed to study the antifungal properties of fermented yellow and oriental mustard extracts using nine lactic acid bacteria (LAB) in vitro. Moreover, a chemical characterization of the main phenolic compounds and organic acids were carried out in the extracts. The results highlighted that the yellow mustard, fermented by Lactiplantibacillus plantarum strains, avoided the growth of Fusarium spp. in vitro, showing Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC) values, ranging from 7.8 to 15.6 g/L and 15.6 to 31.3 g/L, respectively. Then, the lyophilized yellow mustard fermented extract by L. plantarum TR71 was applied through spray-on corn ears contaminated with F. verticillioides to study the antimycotoxigenic activity. After 14 days of incubation, the control contained 14.71 mg/kg of FB1, while the treatment reduced the content to 1.09 mg/kg (92.6% reduction). Moreover, no FB2 was observed in the treated samples. The chemical characterization showed that lactic acid, 3-phenyllactic acid, and benzoic acid were the antifungal metabolites quantified in higher concentrations in the yellow mustard fermented extract with L. plantarum TR71. The results obtained confirmed the potential application of fermented mustard extracts as a solution to reduce the incidence of mycotoxins in corn ears.

Structure Activity Relationship for Fumonisin Phytotoxicity.

Fumonisins are mycotoxins produced by a number of species of Fusarium and Aspergillus. They are polyketides that possess a linear polyol structure with two tricarballylic acid side chains and an amine moiety. Toxicity results from their inhibition of Ceramide Synthase (CerS), which perturbs sphingolipid concentrations. The tricarballylic side chains and amine group of fumonisins are key molecular features responsible for inhibiting CerS, however their individual contributions toward overall toxicity are not fully understood. We have recently reported novel, deaminated fumonisins produced by A. niger and have identified an enzyme (AnFAO) responsible for their synthesis. Here we performed a structure/function activity assay to investigate the individual contributions of the tricarballylic acid and amine toward overall fumonisin toxicity. Lemna minor was treated at 40 µM against FB1, hydrolyzed FB1 (hFB1), deaminated FB1 (FPy1), or hydrolyzed/deaminated (hFPy1). Four end points were monitored: plant dry weight, frond surface area, lipidomics, and metabolomics. Overall, hFB1 was less toxic than FB1 and FPy1 was less toxic than hFB1. hFPy1 which lacks both the amine group and tricarballylic side chains was also less toxic than FB1 and hFB1, however it was not significantly less toxic than FPy1. Lipidomic analysis showed that FB1 treatment significantly increased levels of phosphotidylcholines, ceramides, and pheophorbide A, while significantly decreasing the levels of diacylglycerides, sulfoquinovosyl diacylglycerides, and chlorophyll. Metabolomic profiling revealed a number of significantly increased compounds that were unique to FB1 treatment including phenylalanine, asymmetric dimethylarginine (ADMA), S-methylmethionine, saccharopine, and tyrosine. Conversely, citrulline, N-acetylornithine and ornithine were significantly elevated in the presence of hFB1 but not any of the other fumonisin analogues. These data provide evidence that although removal of the tricarballylic side chains significantly reduces toxicity of fumonisins, the amine functional group is a key contributor to fumonisin toxicity in L. minor and justify future toxicity studies in mammalian systems.

Co-occurrence and toxicological relevance of secondary metabolites in dairy cow feed from Thailand.

The occurrence of secondary metabolites and co-contaminants in dairy cow feed samples (n = 115), concentrate, roughage, and mixed feed, collected from Ratchaburi and Kanjanaburi provinces, Thailand, between August 2018 and March 2019 were investigated using LC-MS/MS based multi-toxin method. A total of 113 metabolites were found in the samples. Fungal metabolites were the predominant compounds, followed by plant metabolites. Among major mycotoxins, zearalenone and fumonisins were most frequently detected in concentrate and mixed feed samples, while deoxynivalenol and aflatoxin B1 were found at the frequency lower than 50%. Other metabolites, produced by Aspergillus, Fusarium, Penicillium, and Alternaria species, occurred in the samples. Flavoglaucin, 3-nitropropionic acid, averufin, and sterigmatocystin were the most prevalent Aspergillus metabolites. Common Fusarium metabolites occurring in the samples included moniliformin, beauvericin, and enniatins. For Penicillium metabolites, mycophenolic acid, questiomycin A, quinolactacin A, oxaline, citrinin, and dihydrocitrinone were frequently detected. The toxic Alternaria metabolites, alternariol, and alternariol monomethyl ether showed the high incidence in the samples. Plant metabolites were commonly found, mainly cyanogenic compounds and isoflavones, from cassava and soybean meal used as feed ingredients. Overall, 96.6% of feed samples contained at least two metabolites, in a range from 2 to 69. According to co-contamination of mycotoxins found in feed samples, zearalenone were mostly found in combination with fumonisin B1, deoxynivalenol, and aflatoxin B1. Fumonisin B1 co-occurred with aflatoxin B1 and deoxynivalenol. The mixtures of deoxynivalenol and aflatoxin B1, and of zearalenone, fumonisin B1 and deoxynivalenol were also found. Due to known individual toxicity of fungal and plant metabolites and possible additive or synergistic toxic effects of multi-mycotoxins, the occurrence of these metabolites and co-contaminants should be monitored continuously to ensure food safety through the dairy supply chain.

Fumonisin B1: Mechanisms of toxicity and biological detoxification progress in animals.

Fumonisin B1 (FB1) is a toxic secondary metabolite produced by the Fusarium molds that can contaminate food and feed. It has been found that FB1 can cause systemic toxicity, including neurotoxicity, hepatotoxicity, nephrotoxicity and mammalian cytotoxicity. This review addresses the toxicity studies carried out on FB1 and outlines the probable mechanisms underlying its immunotoxicity, reproductive toxicity, joint toxicity, apoptosis, and autophagy. In the present work, the research progress of FB1 detoxification in recent years is reviewed, which provides reference for controlling and reducing the toxicity of FB1.

Aptamer-Target-Gold Nanoparticle Conjugates for the Quantification of Fumonisin B1.

Fumonisin B1 (FB1), a mycotoxin classified as group 2B hazard, is of high importance due to its abundance and occurrence in varied crops. Conventional methods for detection are sensitive and selective; however, they also convey disadvantages such as long assay times, expensive equipment and instrumentation, complex procedures, sample pretreatment and unfeasibility for on-site analysis. Therefore, there is a need for quick, simple and affordable quantification methods. On that note, aptamers (ssDNA) are a good alternative for designing specific and sensitive biosensing techniques. In this work, the assessment of the performance of two aptamers (40 and 96 nt) on the colorimetric quantification of FB1 was determined by conducting an aptamer-target incubation step, followed by the addition of gold nanoparticles (AuNPs) and NaCl. Although MgCl2 and Tris-HCl were, respectively, essential for aptamer 96 and 40 nt, the latter was not specific for FB1. Alternatively, the formation of Aptamer (96 nt)-FB1-AuNP conjugates in MgCl2 exhibited stabilization to NaCl-induced aggregation at increasing FB1 concentrations. The application of asymmetric flow field-flow fractionation (AF4) allowed their size separation and characterization by a multidetection system (UV-VIS, MALS and DLS online), with a reduction in the limit of detection from 0.002 µg/mL to 56 fg/mL.

Effect of fumonisin B1 on oxidative stress and gene expression alteration of nutrient transporters in porcine intestinal cells.

Fumonisin B1 (FB1 ) is a common environmental mycotoxin produced by molds such as Fusarium verticillioides. The toxin poses health risks to domestic animals, including pigs, through FB1 -contaminanted feed. However, the cytotoxicity of FB1 to porcine intestines has not been fully analyzed. In the present study, the effects of FB1 on oxidative stress and nutrient transporter-associated genes of the porcine intestinal IPEC-J2 cells were explored. FB1 decreased IPEC-J2 proliferation but did not trigger reactive oxygen species (ROS) overproduction. Meanwhile, FB1 reduced the expression levels of the transporters l-type amino acid transporter-1 (y+ LAT1), solute carrier family 7 member 1 (SLC7A1), solute carrier family 1 member 5 (ASCT2), and excitatory amino acid carrier 1 (EAAC1); in addition, FB1 reduced the levels of the fatty acid transporters long-chain fatty acid transport protein 1 (FATP1) and long-chain fatty acid transport protein 4 (FATP4) as well as glucose transporters Na+ /glucose cotransporter 1 (SGLT1) and glucose transporter 2 (GLUT2). FB1 stimulation increased the expression levels of peptide transporter peptide transporter 1 (PepT1) and metal ion transport-related gene zinc transporter 1 (ZNT1). Moreover, metal ion transporter divalent metal transporter 1 (DMT1) expression was depressed by a higher dosage of FB1 . The data indicate that FB1 results in aberrant expression of nutrient transporters in IPEC-J2 cells, thereby exerting its toxicity even though it fails to exert ROS-dependent oxidative stress.

Two regulators of G-protein signaling (RGS) proteins FlbA1 and FlbA2 differentially regulate fumonisin B1 biosynthesis in Fusarium verticillioides.

Fumonisins are a group of mycotoxins produced by maize pathogen Fusarium verticillioides that pose health concerns to humans and animals. Yet we still lack a clear understanding of the mechanism of fumonisins regulation during pathogenesis. The heterotrimeric G protein complex, which consists of canonical subunits and various regulators of G-protein signaling (RGS) proteins, plays an important role in transducing signals under environmental stress. Earlier studies demonstrated that Gα and Gß subunits are positive regulators of fumonisin B1 (FB1) biosynthesis and that two RGS genes, FvFlbA1 and FvFlbA2, were highly upregulated in Gß deletion mutant ∆Fvgbb1. Notably, FvFlbA2 has a negative role in FB1 regulation. While many fungi contain a single copy of FlbA, F. verticillioides harbors two putative FvFlbA paralogs, FvFlbA1 and FvFlbA2. In this study, we further characterized functional roles of FvFlbA1 and FvFlbA2. While ∆FvflbA1 deletion mutant exhibited no significant defects, ∆FvflbA2 and ∆FvflbA2/A1 mutants showed thinner aerial hyphal growth while promoting FB1 production. FvFlbA2 is required for proper expression of key conidia regulation genes, including putative FvBRLA, FvWETA, and FvABAA, while suppressing FUM21, FUM1, and FUM8 expression. Split luciferase assays determined that FvFlbA paralogs interact with key heterotrimeric G protein components, which in turn will lead altered G-protein-mediated signaling pathways that regulate FB1 production and asexual development in F. verticillioides.

Risk of exposure to aflatoxin B1, ochratoxin A, and fumonisin B1 from spices used routinely in Lebanese cooking.

Spices are susceptible to mycotoxin contamination which can cause gastrointestinal and adverse central nervous symptoms in humans, which highlights the importance of assessing the risk of their consumption on a daily basis. The aim of this study was to assess the risk of mycotoxin intake from spices in routinely prepared Lebanese dishes. 150 households were interviewed about their usage of 27 type of spices and 6 routinely prepared Lebanese dishes. Results showed a high variability in consumption levels. Among the investigated dishes, the minimum number of spices that were consumed in a dish was 13 while the maximum was 18. The mean intake of one spice ranged from 0.26 g/portion observed for cloves to 5.37 g/portion for cinnamon, with its intake per portion more than 1 g in 2/3 of dishes. 20% of portion sizes of coriander, cinnamon and fennel, had an intake exceeding 5 g/portion. Ochratoxin A (OTA) Probable Daily Intake (PDI) had a mean of 0.11 ng/kg-bw/day. Mean PDI of fumonisin B1 (FB1) was 79.3 ng/kg-bw/day. Aflatoxin B1 (AFB1) PDI had a mean of 1.55 ng/kg-bw/day. The Margin of Exposure (MOE) of AFB1 ranged from 108.10 to 4444.44. The present study showed that the risk of AFB1 from spices is a matter of concern while the risk of OTA and FB1 is limited with the exception of FB1 from garlic and onion.

Biological detoxification of fumonisin by a novel carboxylesterase from Sphingomonadales bacterium and its biochemical characterization.

Fumonisins have posed hazardous threat to human and animal health worldwide. Enzymatic degradation is a desirable detoxification approach but is severely hindered by serious shortage of detoxification enzymes. After mining enzymes by bioinformatics analysis, a novel carboxylesterase FumDSB from Sphingomonadales bacterium was expressed in Escherichia coli, and confirmed to catalyze fumonisin B1 to produce hydrolyzed fumonisin B1 by liquid chromatography mass spectrometry for the first time. FumDSB showed high sequence novelty, sharing only ~34% sequence identity with three reported fumonisin detoxification carboxylesterases. Besides, FumDSB displayed its high degrading activity at 30-40 °C within a broad pH range from 6.0 to 9.0, which is perfectly suitable to be used in animal physiological condition. It also exhibited excellent pH stability and moderate thermostability. This study provides a FB1 detoxification carboxylesterase which could be further used as a potential food and feed additive.

Quantification of multi-mycotoxin in cereals (maize, maize porridge, sorghum and wheat) from Limpopo province of South Africa.

Mycotoxins are secondary metabolites that are produced by filamentous mycotoxigenic fungi belonging to the Alternaria, Aspergillus, Fusarium and Penicillium genera amongst others. Multi-class mycotoxins were extracted from 55 cereal samples and analysed using liquid chromatography-tandem mass spectrometry. The adopted extraction method for maize, maize porridge, sorghum and wheat was comprehensively validated. This method was further tested to determine the natural occurrence of mycotoxins in foodstuffs. Twelve (12) out of 22 mycotoxins were detected in maize, maize porridge, sorghum and wheat, including α-zearalenol (α-ZEL) (89%), fumonisin B3 (FB3) (84%), fumonisin B1 (FB1) (80%), tenuazonic acid (TeA) (78%), ochratoxin B (42%), deoxynivalenol (DON) (12%), ochratoxin A (11%), 3-acetyldeoxynivalenol (7%), sterigmatocystin (STG) (6%), 15-acetyldeoxynivalenol (2%), cyclopiazonic acid (CPA) (2%) and aflatoxin B2 (2%). The data revealed high incidence rate of α-ZEL (range: 6.5-70.5 µg kg-1) in all matrices. Maize samples had high mycotoxin co-occurrence compared to other matrices. All recovered mycotoxins in food commodities were within the maximum regulatory limits, with the exception of fumonisins (FB1 and FB3) exceeded the South African and European Commission regulation, and the highest concentration was 2153 µg kg-1 in maize. It is essential to monitor the level of emerging mycotoxins in food commodities from rural areas as trace amount of CPA (< limit of quantification), STG (range: 0.30-0.74 µg kg-1) were detected and high concentration of TeA (292.7 µg kg-1) was detected in sorghum. The occurrence of these mycotoxins further encourages frequent analyses, their co-occurrence in the samples poses a significant threat to public health and more emphasis should thus be placed on reducing the contamination levels of these toxins in staples.

Trimer-based aptasensor for simultaneous determination of multiple mycotoxins using SERS and fluorimetry.

An aptasensor is reported for the detection of three different kinds of mycotoxins, i.e., zearalenone (ZEN), ochratoxin A (OTA), and fumonisin B1 (FB1). Based on fluorescence resonance energy transfer effect (FRET) and surface-enhanced Raman scattering (SERS), the levels of ZEN, FB1, and OTA can be simultaneously determined. Under 980-nm and 650-nm laser excitation, the logarithmic values of fluorescence signal intensities at 543 nm and 670 nm are slowly increased as the concentrations of ZEN and OTA vary from 0.1 ng mL-1 and 0.05 ng mL-1 to 100 ng mL-1 and 25 ng mL-1, respectively. For FB1, under 980-nm laser excitation, the logarithmic value of SERS signal intensity at 1567 cm-1 gradually increases with the concentration of FB1 in the range 0.05-200 pg mL-1 (R2 = 0.996). The detection limits of the proposed assay for ZEN, OTA, and FB1 are 0.03 ng mL-1, 0.01 ng mL-1, and 0.02 pg mL-1, respectively. The selectivity experiment results indicate this assay possesses a high selectivity over other commonly encountered mycotoxins. The average recoveries range from 90 to 107%, revealing satisfactory application potential of the proposed assay. The developed aptasensor will bring bright prospects for research in the field of multiplexed mycotoxine detection. Graphical Abstract Schematic representation of an aptamer-based assay for multiple mycotoxins determination.

Evaluation of the Individual and Combined Toxicity of Fumonisin Mycotoxins in Human Gastric Epithelial Cells.

Fumonisin contaminates food and feed extensively throughout the world, causing chronic and acute toxicity in human and animals. Currently, studies on the toxicology of fumonisins mainly focus on fumonisin B1 (FB1). Considering that FB1, fumonisin B2 (FB2) and fumonisin B3 (FB3) could coexist in food and feed, a study regarding a single toxin, FB1, may not completely reflect the toxicity of fumonisin. The gastrointestinal tract is usually exposed to these dietary toxins. In our study, the human gastric epithelial cell line (GES-1) was used as in vitro model to evaluate the toxicity of fumonisin. Firstly, we found that they could cause a decrease in cell viability, and increase in membrane leakage, cell death and the induction of expression of markers for endoplasmic reticulum (ER) stress. Their toxicity potency rank is FB1 > FB2 >> FB3. The results also showed that the synergistic effect appeared in the combinations of FB1 + FB2 and FB1 + FB3. Nevertheless, the combinations of FB2 + FB3 and FB1 + FB2 + FB3 showed a synergistic effect at low concentration and an antagonistic effect at high concentration. We also found that myriocin (ISP-1) could alleviate the cytotoxicity induced by fumonisin in GES-1 cells. Finally, this study may help to determine or optimize the legal limits and risk assessment method of mycotoxins in food and feed and provide a potential method to block the fumonisin toxicity.

Competitive HRP-Linked Colorimetric Aptasensor for the Detection of Fumonisin B1 in Food based on Dual Biotin-Streptavidin Interaction.

Fumonisin B1 (FB1) is the most prevalent and toxic form among fumonisin homologues which are produced by fusarium species and it contaminates various types of food products, posing serious health hazards for humans and animals. In this work, a colorimetric assay for the detection of FB1 has been developed based on competitive horseradish peroxidase (HRP)-linked aptamer and dual biotin-streptavidin interaction. In short, a biotinylated aptamer of FB1 was immobilized on the microplate by biotin-streptavidin binding; the complementary strand (csDNA) of the aptamer was ligated with HRP by biotin-streptavidin binding again to form a csDNA-HRP sensing probe, competing with FB1 to bind to the aptamer. The color change can be observed after the addition of chromogenic and stop solution, thereby realizing the visual detection of FB1. Under optimal conditions, good linearity was observed within the concentration range of 0.5 to 300 ng/mL, with a detection of limit of 0.3 ng/mL. This assay is further validated by spike recovery tests towards beer and corn samples, it provides a simple, sensitive and reliable method for the screening of FB1 in food samples and may be potentially used as an alternative to conventional assays.

A fluorometric method for aptamer-based simultaneous determination of two kinds of the fusarium mycotoxins zearalenone and fumonisin B1 making use of gold nanorods and upconversion nanoparticles.

An aptamer-based assay for the determination of two different kinds of fusarium mycotoxins, i.e., zearalenone (ZEN) and fumonisin B1 (FB1), is presented. Based on the inner filter effect (IFE) strategy, the contents of ZEN and FB1 can be simultaneously quantified. It is making use of 65-nm gold nanorods (AuNRs), 20-nm upconversion nanoparticles (UCNPs), fluorescence dyes, and DNA sequences. In the absence of ZEN and FB1, the UCNPs and AuNRs associate through DNA sequences. Due to IFE effect, weak fluorescence signals are collected. In the presence of ZEN or FB1, UCNPs and AuNRs become unstable and partially separate from each other. This results in the recovery of fluorescence signals. Under 980-nm laser excitation, the logarithmic values of fluorescence signal intensities at 606 nm and 753 nm gradually increase with the concentration of ZEN and FB1 in the ranges 0.05-100 µg L-1 (the coefficient of determination is 0.997) and 0.01-100 ng L-1 (the coefficient of determination is 0.986), respectively. The limits of detection (LOD) of the fabricated assay for ZEN and FB1 are 0.01 µg L-1 and 0.003 ng L-1, respectively. The proposed method has a high selectivity over other competitive mycotoxins, including aflatoxin B1, ochratoxin A, patulin and ochratoxin B. The applicability of the assay was evaluated in the determination of ZEN and FB1 contents in spiked corn samples. The average recoveries ranged from 89.9 to 106.6%. This result confirms the practicality of this method. Graphical abstract Schematic representation of an aptamer-based fluorometric method for simultaneous determination of two kinds of the fusarium mycotoxins zearalenone and fumonisin B1.

Preparative isolation and purification of B-type fumonisins by using macroporous resin column and high-speed countercurrent chromatography.

B-type fumonisins (FBs) are water-soluble mycotoxins produced by Fusarium species, which are mainly found in maize products and threaten food safety. Toxicological studies and quantitative determinations of fumonisins require large amounts of pure toxins, and their high prices limit progress in FBs research. In this study, we used a macroporous resin column combined with high-speed countercurrent chromatography to separate large quantities of FBs. A fermented rice culture was extracted with 75% methanol. The dynamic adsorption capacity of FBs on XAD-2 resin was 27.5 mg/g resin at 25°C, pH 4.0, and then the FBs were desorbed with 60% methanol. The crude FBs were further purified using a biphasic system consisting of n-heptane/n-butanol/methanol/water (2:4:1:4, v/v/v/v). The method yielded 1.55 g of FB1 and 0.55 g of FB3 with purities of 96.8% and 95.6%, respectively, from 1 kg of rice culture, and the final overall yield of FBs was 74.8%.