Aflatoxin G2

Assessing Aflatoxin Exposure Risk from Peanuts and Peanut Products Imported to Taiwan.[Pubmed:30717134]

Toxins (Basel). 2019 Feb 1;11(2). pii: toxins11020080.

Aflatoxins are highly toxic and cause disease in livestock and humans. In order to assess Taiwan population exposure to aflatoxin from peanuts and peanut products, a total of 1089 samples of peanut candy, peanut butter, and peanuts etc. were collected in the period from 2011 to 2017 and analyzed using a liquid chromatography/tandem mass spectrometer. The overall mean contamination levels of aflatoxin in peanuts and peanut products were 2.40 mug/kg of aflatoxin B1, 0.41 mug/kg of aflatoxin B2, 0.19 mug/kg of aflatoxin G1, and 0.03 mug/kg of Aflatoxin G2. We use margin of exposure (MOE) as a tool to improve food safety management. According to MOE levels of aflatoxins in peanuts and peanut products from China, Indonesia, Thailand, the United States, and the Philippines were above the safe lower limit of 10,000, indicating an absence of public health or safety risk for the majority of the population. However, products from Vietnam were under the MOE safe lower limit, suggesting that regulatory actions must be continued to avoid excessive consumer exposure.

A miniaturized solid-phase extraction adsorbent of calix[4]arene-functionalized graphene oxide/polydopamine-coated cellulose acetate for the analysis of aflatoxins in corn.[Pubmed:30098128]

J Sep Sci. 2018 Oct;41(20):3892-3901.

A calix[4]arene-functionalized graphene oxide/polydopamine-coated cellulose acetate adsorbent was fabricated for the pre-concentration of aflatoxins. The highly porous developed adsorbent does not produce the high backpressure that normally occurs in particle-packed cartridges and its large surface area helps to improve adsorption. The highly efficient adsorption of aflatoxins by the hybrid adsorbent is facilitated via hydrogen bonding and hydrophobic and pi-pi interactions. Polymerization time, amount of calix[4]arene-functionalized graphene oxide, type and volume of desorption solvent, sample pH, sample volume, and sample flow rate were optimized. The linearity of aflatoxin B1 was in the range of 0.01-10.0 mug/kg, aflatoxin B2 was in the range of 0.02-10.0 mug/kg and aflatoxin G1 and Aflatoxin G2 were in the range of 0.050-10.0 mug/kg. The limits of detection were 0.01 mug/kg for aflatoxin B1, 0.02 mug/kg for aflatoxin B2 and 0.05 mug/kg for aflatoxin G1 and Aflatoxin G2. The developed calix[4]arene-functionalized graphene oxide/polydopamine-coated cellulose acetate adsorbent was successfully utilized for the analysis of aflatoxins from corn samples and the extraction efficiency was satisfactory with obtained recoveries from 83.0 to 106.7%. Moreover, fabricated adsorbent is easy to prepare, inexpensive, and can be reused.

Direct fluorescence anisotropy approach for aflatoxin B1 detection and affinity binding study by using single tetramethylrhodamine labeled aptamer.[Pubmed:30086944]

Talanta. 2018 Nov 1;189:442-450.

The discovery of aptamers for aflatoxin B1 (AFB1), one of toxic carcinogens, has allowed to develop aptamer-based sensors and assays for aflatoxin. In this work, we reported a direct fluorescence anisotropy (FA) assay for investigation of aptamer-AFB1 binding and detection of AFB1 with the aptamer having single tetramethylrhodamine (TMR) label on a specific site. From a series of labeling sites of a 50-mer aptamer, we screened out the aptamer with TMR labeling at the 26th T, capable of generating good and large FA-decreasing response to AFB1. By using the T26-labeled 50-mer aptamer probe in FA analysis, we determined the affinity and selectivity of aptamer, and identified the crucial region of aptamer and optimum experimental conditions for strong binding. The aptamer could be further truncated to as short as 26 nucleotides in length, and this shorter aptamer possessed a simple stem-loop secondary structure and retained good binding affinity. Nucleotides in the loop region of the aptamer were conserved and important for affinity recognition. We achieved FA detection of AFB1 with a detection limit about 2nM by using the TMR-labeled aptamer probe. The cross reactivity of aflatoxin B1, aflatoxin B2, aflatoxin M1, aflatoxin M2, aflatoxin G1, and Aflatoxin G2 with aptamer were estimated to be 100%, 61%, 23%, 21%, 6.3%, 6.5%, respectively. The aptamer probe presented good selectivity over other mycotoxins and showed potential in complex sample analysis. This study of affinity binding between aptamer and aflatoxins will be helpful for developing other aptamer-based assays and sensors for aflatoxins.

A feasibility study of producing a peanut oil matrix candidate reference material and its application to support monitoring of aflatoxins statues for public health purposes.[Pubmed:30064774]

Food Chem. 2018 Dec 1;268:395-401.

The first peanut oil reference materials in naturally contaminated aflatoxins was developed, because of the high consumption of this product and the potential risk associated herewith. Based on liquid chromatographic method, homogeneity, short-term of 60 degrees C for seven days and long-term of 25 degrees C for twelve months' stability studies of candidates were assessed. The obtained data and statistical results showed a successful feasibility study, without any significant trend. Nine selected expert laboratories were invited to certify the contents of candidates using distinguish quantitative liquid chromatographic method. The certified values and expanded uncertainties (k=2) for these two batches were 6.5+/-1.6mug/kg, 29.3+/-5.3mug/kg for aflatoxin B1; 1.2+/-0.3mug/kg, 5.2+/-0.9mug/kg for aflatoxin B2; 5.0+/-0.4mug/kg, 8.4+/-0.7mug/kg for aflatoxin G1; and 2.1+/-0.2mug/kg, 3.5+/-0.2mug/kg for Aflatoxin G2, respectively.

Mycotoxin contamination of sorghum and its contribution to human dietary exposure in four sub-Saharan countries.[Pubmed:29912638]

Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2018 Jul;35(7):1384-1393.

This research aimed at evaluating the safety, and the type, level and prevalence of mycotoxins in grain sorghum of four sub-Saharan African (SSA) countries (Burkina Faso, Ethiopia, Mali and Sudan). A multi-analyte LC-MS/MS method for quantification of 23 mycotoxins (nivalenol, deoxynivalenol, fusarenon X, neosolaniol, 3-acetyl deoxynivalenol, 15-acetyl deoxynivalenol, diacetoxyscirpenol, roquefortine C, HT-2 toxin, alternariol, T-2 toxin, FB1, FB2, FB3, zearalenone, aflatoxin G1, Aflatoxin G2, aflatoxin B1, aflatoxin B2, sterigmatocystin, OTA, altenuene, alternariol monomethylether) was applied to different sorghum matrices. Of the 1533 analysed samples, 33% were contaminated with at least one of the following mycotoxins: aflatoxins, fumonisins, sterigmatocystin, Alternaria toxins, OTA and zearalenone. Country of origin, colour, source and collection period of sorghum samples significantly influenced the type, level and prevalence of mycotoxins. Sterigmatocystin (15%), fumonisins (17%) and aflatoxins (13%) were the most prevalent. FB1 (274 +/- 585 microg/kg) had the highest mean concentration followed by FB2 (214 +/- 308 microg/kg) while diacetoxyscirpenol (8.12 +/- 19.2 microg/kg) and HT-2 (11.9 +/- 0.00 microg/kg) had the lowest concentrations. Neosolaniol, fusarenon-X, 3-acetyl deoxynivalenol, 15-acetyl deoxynivalenol, T-2 toxin, nivalenol and roquefortine C were not detected in any of the samples. Sudan had the lowest prevalence and mean concentration of all mycotoxins. Pink sorghum had the highest concentrations of fumonisins and aflatoxins. Mycotoxins from Aspergillus spp. and Alternaria spp. are the mycotoxins of concern in SSA grain sorghum with regard to prevalence, concentration and possible health risk from exposure. Based on the performed risk characterisation, daily consumption of sorghum containing aflatoxins, alternariol, alternariol monomethyl ether, sterigmatocystin and OTA could result in exceeding the established health-based guidance values for these toxins.

Liquid chromatography - high resolution mass spectrometry method for monitoring of 17 mycotoxins in human plasma for exposure studies.[Pubmed:29576275]

J Chromatogr A. 2018 May 4;1548:51-63.

Mycotoxins are secondary metabolites produced by filamentous fungi. Primary route of human exposure to mycotoxins is the intake of the contaminated food. Minimizing mycotoxin exposure is important for population health, as their chronic toxic effects have been associated with kidney and liver diseases, some types of cancer and immunosuppression. The objective of this work was to develop and validate a multi-class mycotoxin method suitable for exposure monitoring of mycotoxins in human plasma. A sensitive liquid chromatography - mass spectrometry method was developed for 17 mycotoxins: nivalenol (NIV), deoxynivalenol, fusarenon X, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, T-2 toxin, HT-2 toxin, aflatoxin B1, aflatoxin B2, aflatoxin G1, Aflatoxin G2, zearalenone, alpha-zearalenol (alpha-ZOL), beta-zearalenol, zearalanone, alpha-zeranol and, and beta-zeranol. The method relies on three-step liquid-liquid extraction with ethyl acetate to eliminate the need for immunoaffinity extraction and minimize ionization matrix effects. Chromatographic separation of mycotoxins, including all isomers, was achieved with pentafluorophenyl column and water/methanol mobile phase. Mycotoxin detection and quantitation were performed using high-resolution mass spectrometry on LTQ Velos Orbitrap, in both positive and negative electrospray ionization (ESI(+) and (ESI(-)). The use of 0.02% acetic acid as mobile phase additive for ESI(-) resulted in significant increase in ionization efficiency ranging from 1.7 to 26 times for mycotoxins that ionize better in ESI(-). The optimized method was validated according to FDA guidance procedures. LOQs of all mycotoxins ranged from 0.1 to 0.5ng/ml, except NIV which resulted in LOQ of 3ng/ml because of low extraction recovery of this highly polar mycotoxin. Mean intra-day accuracy ranged from 85.8% to 116.4%, and intra-day precision (n=6) ranged from 1.6% to 12.5% RSD for all mycotoxins except alpha-ZOL where mean accuracy ranged from 72.9% to 97.2%. Inter-day accuracy and precision were 85.6%-111.5% and 2.7-15.6% RSD respectively, showing good analytical performance of the method for biomonitoring.

[Determination of mycotoxins in pu-erh tea, black tea, and green tea samples].[Pubmed:29493150]

Zhongguo Zhong Yao Za Zhi. 2017 Dec;42(24):4801-4806.

To establish a robust method for the determination of mycotoxins in tea samples, and to provide means for the quality and safety control of tea products. Samples of 20 tea products acquired from international market were extracted by organic solvents (acetonitrile containing 0.1% formic acid) or hot water, respectively. The extracts were analyzed by UPLC-MS/MS.A good linear regression was achieved in a range of 39.1 to 5 000 ng*L(-)(1) for aflatoxin B1 (AFB1) and aflatoxin G1 (AFG1), 117 to 15 000 ng*L(-)(1) for aflatoxin B2 (AFB2) and Aflatoxin G2 (AFG2), 2.44 to 313 ng*L(-)(1) for fumonisin B1 (FB1), fumonisinB2 (FB2) and fumonisin B3 (FB3), and 3 125 to 5 000 ng*L(-)(1) for deoxynivalenol, with recovery rates between 85.7% and 99.6%. The coefficient of the linear equation for all standards was greater than 0.999 0, and the RSD value was less than 10%. Mycotoxins were detected in several tea samples using the two extraction methods but with different outcomes. The levels of mycotoxins detected ranging from 0.15 to 7.31 mug*kg(-)(1) were well below the State or US FDA regulation limits of mycotoxins in food products. Both methods are simple, accurate, and sensitive, and thus, suitable for the quantitative determination of mycotoxins in different food products. The method with the 80 hot-water extraction is more appropriate to determine the trace amounts of mycotoxins in tea leaves that are likely to be present in brewed tea liquor, while organic solvent method is more suitable for the detection of mycotoxins in ingestible foods.

Reduced Graphene Oxide-Gold Nanoparticle Nanoframework as a Highly Selective Separation Material for Aflatoxins.[Pubmed:29101380]

Sci Rep. 2017 Nov 3;7(1):14484.

Graphene-based materials have been studied in many applications, owing to the excellent electrical, mechanical, and thermal properties of graphene. In the current study, an environmentally friendly approach to the preparation of a reduced graphene oxide-gold nanoparticle (rGO-AuNP) nanocomposite was developed by using L-cysteine and vitamin C as reductants under mild reaction conditions. The rGO-AuNP material showed a highly selective separation ability for 6 naturally occurring aflatoxins, which are easily adsorbed onto traditional graphene materials but are difficult to be desorbed. The specificity of the nanocomposite was evaluated in the separation of 6 aflatoxin congeners (aflatoxin B1, aflatoxin B2, aflatoxin G1, Aflatoxin G2, aflatoxin M1 and aflatoxin M2) from 23 other biotoxins (including, ochratoxin A, citrinin, and deoxynivalenol). The results indicated that this material was specific for separating aflatoxin congeners. The synthesized material was further validated by determining the recovery (77.6-105.0%), sensitivity (limit of detection in the range of 0.05-0.21 mug kg(-1)), and precision (1.5-11.8%), and was then successfully applied to the separation of aflatoxins from real-world maize, wheat and rice samples.

Optimized QuEChERS Method Combined with UHPLC-MS/MS for the Simultaneous Determination of 15 Mycotoxins in Liquorice.[Pubmed:29073944]

J AOAC Int. 2018 May 1;101(3):633-642.

In our study, a reliable and rapid analytical method for the simultaneous determination of 15 mycotoxins (aflatoxin B1, aflatoxin B2, aflatoxin G1, Aflatoxin G2, alternariol, agroclavine, citrinin, diacetoxyscirpenol, deoxynivalenol, fumonisin B1, fumonisin B2, ochratoxin A, sterigmatocystin, T-2 toxin, and zearalenone) in liquorice using ultra-HPLC coupled to tandem MS was developed and validated. Due to the complex ingredients in liquorice, we chose a QuEChERS-based extraction procedure as the sample pretreatment. Meanwhile, for the first time, acetate buffer was used to replaced water, which can greatly reduce the concentration of formic acid in acetonitrile, which further reduces the extraction efficiency of impurities. The optimal combination of adsorbents is 150 mg primary secondary amine, 150 mg silica gel, 600 mg octadecylsilane, and 900 mg anhydrous magnesium sulfate. Electrospray ionization in both positive- and negative-ionization modes was applied to detect all the mycotoxins in a single run time of 15 min, with LOQs in the range of 0.125-2.5 mug/kg. The recoveries of determination obtained were in the range of 81.0-104.7%, whereas the analytes could be accurately quantified in the 0.25-625 mug/kg concentration range, with all coefficients being >0.992. Intra- and interday reproducibility were lower than 5.5 and 8.9%, respectively, for all analytical mycotoxins. The validated method was finally applied to screen mycotoxins in 31 batches of real samples collected from drugstores and hospitals in Shanghai, China. Our survey findings show that six mycotoxins were detected, including alternariol, citrinin, deoxynivalenol, fumonisin B1, ochratoxin, and zearalenone, and that the positive rate of mycotoxins was 54.8% in real samples, ranging from 3.37 to 520.6 mug/kg.

Fluorescent sensor systems based on nanostructured polymeric membranes for selective recognition of Aflatoxin B1.[Pubmed:28841965]

Talanta. 2017 Dec 1;175:101-107.

Nanostructured polymeric membranes for selective recognition of aflatoxin B1 were synthesized in situ and used as highly sensitive recognition elements in the developed fluorescent sensor. Artificial binding sites capable of selective recognition of aflatoxin B1 were formed in the structure of the polymeric membranes using the method of molecular imprinting. A composition of molecularly imprinted polymer (MIP) membranes was optimized using the method of computational modeling. The MIP membranes were synthesized using the non-toxic close structural analogue of aflatoxin B1, ethyl-2-oxocyclopentanecarboxylate as a dummy template. The MIP membranes with the optimized composition demonstrated extremely high selectivity towards aflatoxin B1 (AFB1). Negligible binding of close structural analogues of AFB1 - aflatoxins B2 (AFB2), Aflatoxin G2 (AFG2), and ochratoxin A (OTA) was demonstrated. Binding of AFB1 by the MIP membranes was investigated as a function of both type and concentration of the functional monomer in the initial monomer composition used for the membranes' synthesis, as well as sample composition. The conditions of the solid-phase extraction of the mycotoxin using the MIP membrane as a stationary phase (pH, ionic strength, buffer concentration, volume of the solution, ratio between water and organic solvent, filtration rate) were optimized. The fluorescent sensor system based on the optimized MIP membranes provided a possibility of AFB1 detection within the range 14-500ngmL(-1) demonstrating detection limit (3) of 14ngmL(-1). The developed technique was successfully applied for the analysis of model solutions and waste waters from bread-making plants.

Aflatoxin G2 is a major naturally produced aflatoxin. Aflatoxin G2 is a mycotoxin produced by the fungi Aspergillus flavus and Aspergillus parasiticus.The level of toxicity associated with Aflatoxin is Aflatoxin B1>Aflatoxin M1>Aflatoxin G1>Aflatoxin B2>Aflatoxin M2>Aflatoxin G2.

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