Terminal Furan Ring Research Articles

Detoxification of aflatoxin B1 by a Bacillus subtilis spore coat protein through formation of the main metabolites AFQ1 and epi-AFQ1.

A variety of important agricultural crops host fungi from the Aspergillus genus can produce cancerogenic secondary metabolites such as aflatoxins. Consequently, novel strategies for detoxification and their removal from food and feed chains are required. Here, detoxification of Aflatoxin B1 (AFB1) by the Bacillus subtilis multi-copper oxidase CotA (BsCotA) was investigated. This laccase was recombinantly produced in E. coli while codon optimization led to duplication of the amount of active protein obtained. CuCl2 was added to the cultivation medium leading to a 25-fold increase of V max corresponding to improved incorporation of Cu2+ into the enzyme protein which is essential for the catalytic reaction. To avoid potential cytotoxicity of Cu2+, cultivation was performed at microaerobic conditions indeed leading to 100x more functional protein when compared to standard aerobic conditions. This was indicated by an increase of V max from 0.30 ± 0.02 to 33.56 ± 2.02 U/mg. Degradation kinetics of AFB1 using HPLC with fluorescence detection (HPLC-FLD) analysis indicated a theoretical substrate saturation above solubility in water. At a relatively high concentration of 500 μg/L, AFB1 was decomposed at 10.75 μg/Lh (0.17 nmol*min-1*mg-1) at a dosage of 0.2 μM BsCotA. AFQ1 and epi-AFQ1 were identified as the initial oxidation products according to mass spectrometry (i.e., HPLC-MS, HPLC-QTOF). None of these molecules were substrates for laccase but both decomposed in buffer. However, decomposition does not seem to be due to hydration of the vinyl ether in the terminal furan ring. Genotoxicity of the formed AFB1 was assessed in several dilutions based on the de-repression of the bacterial SOS response to DNA damage indicating about 80-times reduction in toxicity when compared to AFQ1. The results of this study indicate that BsCotA has high potential for the biological detoxification of aflatoxin B1.

Achieving improved efficiency for removal of aflatoxin B1 by combination use of cold atmospheric-pressure plasma and plasma-activated water

A novel approach was employed to remove aflatoxin B1 (AFB1), a very toxic metabolite from Aspergillus flavus (A. flavus), by using cold atmospheric-pressure plasma (CAP) and plasma-activated water (PAW) in combination. The results showed that CAP could efficiently degrade AFB1, while the PAW produced by CAP could further remove AFB1 with a relatively long treatment time. During the CAP processing, hydroxyl radical (·OH) was one of the dominant reactive species, which caused the hydroxylation at furan ring of AFB1, while in PAW treatment, singlet oxygen (1O2) was the major reactive agent for AFB1 degradation, which caused the destruction of the methyl group on the benzene side chain and oxidized the double bond of the terminal furan ring in the AFB1 molecule. This study therefore provides new guidance for the application of plasma technology in the treatment of fungal mycotoxins for food safety.

G-C3N5 nanotube as a promising candidate for adsorption and inactivation of aflatoxin B1: A first-principles study

A novel method for the detection and inactivation of aflatoxin B1 (AFB1) is presented based on the first-principles method. We first investigate g-C3N5 nanotubes for the adsorption of AFB1 and then achieve the adsorption and inactivation of AFB1 on the g-C3N5 nanotubes with the OH group. The calculated results demonstrate that the band gaps of both armchair and zigzag g-C3N5 nanotubes decrease as the diameters increase and gradually converge to that of the g-C3N5 nanosheet. AFB1 prefers to adsorb at site C of g-C3N5 nanotubes. AFB1 reduces the band gap and enhances the electrical conductivity of pristine g-C3N5 nanotubes. The introduction of the OH group on the g-C3N5 nanotubes could destroy the C=C of the terminal furan ring of AFB1 and form a new substance AFB1–9‑hydroxy (AFB1OH), resulting in the inactivation of the toxicity of AFB1. Thus g-C3N5 nanotubes may be not only a superior adsorbent but also a promising sensing and inactivation medium for AFB1 in future applications.

Reactive molecular dynamics simulation on degradation of aflatoxin B1 by cold atmospheric plasmas

Aflatoxins pose a threat to humans and animals and are not easily degraded. Cold atmospheric plasma (CAP) can effectively decontaminate aflatoxins in foods. In this study, a Reactive Molecular Dynamics (RMD) simulation was carried out to examine the interactions of reactive oxygen species (ROS) produced in CAP and aflatoxin B1 (AFB1). The simulation results indicated that ROS (O atoms, OH radicals, and H2O2 molecules considered in present study) can reduce the toxicity of AFB1 by the addition reaction of the double C8C9 bond, the ring-opening reaction of the terminal furan ring, and the destruction of the lactone ring. The ketone carbonyl reduction and double CC bonds formation of cyclopentenone can also be observed in the simulation. The reaction pathways and the final products unveiled by simulation results agree well with the experimental observations, which clearly indicate that CAP can degrade AFB1 by destroying the key structures of AFB1 in a non-thermal way, and further suggest the optimized way to degrade aflatoxins in applications. Industrial relevanceReactive Molecular Dynamics simulations were applied to visualize the chemical damaging mechanism of AFB1 upon the impact of reactive oxygen species during food processing by cold atmospheric plasma (CAP). Such detailed information about the pathways of specific ROS is difficult to obtain experimentally. These results can be used to understand the structural changes at the atomic level that could provide theoretical instruction to industrialists. This work can also contribute to the optimization of process parameters to drive the improvement of operating conditions and the development of CAP sources in the food industry.

Highly efficient adsorption and catalytic degradation of aflatoxin B1 by a novel porous carbon material derived from Fe-doped ZIF-8

The development of peroxymonosulfate (PMS) catalysts with sufficient active sites and high mass transfer capacity is a desirable but challenging aspect in advanced oxidation processes. In this work, an Fe/N-co-doped porous carbon (Fe/N-PC) material derived from silica-coated Fe-doped zeolitic imidazolate framework-8 (Fe-ZIF-8) was developed and used as catalyst for the degradation of aflatoxin B1 (AFB1). Fe-ZIF-8 introduced additional Fe-N sites with high catalytic PMS activity. Importantly, the strategy of silica coating on the surface of Fe-ZIF-8 effectively prevented the aggregation of catalyst particles during the pyrolysis process and introduced a hierarchical porous structure in Fe/N-PC, significantly improving the mass transfer of reactants on the catalyst. As a result, Fe/N-PC possessed a much higher adsorption capacity for AFB1 (202.8 mg g−1) than other reported carbon adsorbents and exhibited fast degradation of AFB1 with ultra-high removal efficiency (99.88%) within 30 min. Singlet oxygen (1O2) was proved to be the dominant reactive species for AFB1 degradation. In addition, four degradation products were identified, and two possible degradation pathways were proposed. The double bond of the terminal furan ring or the methoxy group was destroyed, which implied that the toxicity of the degradation products was significantly reduced. Based on the above results, Fe/N-PC can be considered an efficient catalyst for the removal of hard-to-degrade AFB1 in practical applications.

Structure Elucidation and Toxicity Analysis of the Byproducts Formed after Biodegradation of Aflatoxins B1 and B2 Using Extracts of Mentha arvensis.

The aqueous extracts of leaves and shoots of Mentha arvensis were checked for their potential to biodegrade aflatoxin B1 and B2 (AFB1; 100 µg/L and AFB2; 50 µg/L) through in vitro assays. Overall, the results showed that leaf extract degrades aflatoxins more efficiently than the shoot extract. First, the pH, temperature and incubation time were optimized for maximum degradation by observing this activity at different temperatures between 25 and 60 °C, pH between 2 and 10 and incubation time from 3 to 72 h. In general, an increase in all these parameters significantly increased the percentage of biodegradation. In vitro trials on mature maize stock were performed under optimized conditions, i.e., pH 8, temperature 30 °C and an incubation period of 72 h. The leaf extract resulted in 75% and 80% biodegradation of AFB1 and AFB2, respectively. Whereas the shoot extract degraded both toxins up to 40–48%. The structural elucidation of degraded toxin products by LCMS/MS analysis showed seven degraded products of AFB1 and three of AFB2. MS/MS spectra showed that most of the products were formed by the loss of the methoxy group from the side chain of the benzene ring, the removal of the double bond in the terminal furan ring and the modification of the lactone group, indicating less toxicity compared to the parent compounds. The degraded products showed low toxicity against brine shrimps, confirming that M. arvensis leaf extract has significant potential to biodegrade aflatoxins.

Degradation of aflatoxin B1 by water-assisted microwave irradiation: Kinetics, products, and pathways

The effect of aflatoxin B1 (AFB1) degradation by water-assisted microwave irradiation (WMI) and the identification of the degradation products of AFB1 are key issues in the feasibility study of WMI detoxification. In this study, WMI was applied to degrade pure AFB1 in aqueous medium, and the kinetics, products, and pathways of the degradation of AFB1 were studied. The results showed that AFB1 could be effectively degraded by WMI, and the degradation process followed pseudo-first-order reaction kinetics. In addition, six new main degradation products were identified by ultra-high-performance liquid chromatography Q-Orbitrap mass spectrometry, and a possible degradation pathway was proposed. Furthermore, the variety and quantity of AFB1 degradation products and the degradation pathway of AFB1 were affected by microwave heating temperature, time, and power. After WMI treatment, the double bond in the terminal furan ring or the lactone bond of AFB1 was destroyed, which implied that the toxicity of the degradation product was significantly reduced. Therefore, WMI is deemed to be an effective method to degrade AFB1.

Identification of degradation products of aflatoxin B1 and B2 resulting after their biodetoxification by aqueous extracts ofAcacia nilotica

Contamination of food and feed items with mycotoxins causes extensive economic damage. It is therefore important to explore environmentally friendly approaches to manage these toxins with less drawbacks. Phytochemicals can provide a safe alternative to synthetic chemicals. This study was designed to investigate the detoxification potential of water-based extracts ofAcacia nilotica against aflatoxins B1 and B2. First trials were carried out to standardise temperature, pH and incubation time for biodetoxification in spiked maize. A significant percentage of detoxification was observed under all tested conditions, showing an increasing detoxifying potential with an increase in all three parameters. Leaf extract was found to be more effective than shoot extract. Leaf extract resulted in 86-90% detoxification of both aflatoxin B1 and B2 when incubated for 72 h at 60 °C and pH 10. To avoid the detrimental effects of very high temperature and pH, experiments on spiked maize were conducted at 30 °C and pH 8. A significant detoxification of 82-83% was recorded during trials with spiked maize. MS/MS analyses showed conversion of aflatoxins B1 into seven and aflatoxins B2 into two new compounds. Most of the compounds were formed due to the removal of the double bond in the terminal furan ring and modification of the lactone group, indicating less toxicity as compared to the parent compounds. Decontamination and reduction in toxicity of treated aflatoxins was corroborated by a brine shrimps bioassay.

Unravelling the pathways of air plasma induced aflatoxin B1 degradation and detoxification

Aflatoxins are considered to be a critical dietary risk factor for humans, with aflatoxin B1 (AFB1) identified by the WHO as one of the most potent natural group 1 carcinogen. Despite this, more than half of the world’s population is chronically exposed, resulting in up to 170,000 annual cases of human hepatocellular carcinoma cancer. Here we report an easily implemented approach using non-equilibrium plasma for targeted degradation of AFB1. Apart from reaching the 100 % decontamination in less than 120 s of treatment, this is the first study that combines hypersensitive analytical methods such as high-resolution mass spectroscopy (HRMS) and nuclear magnetic resonance spectroscopy (NMR) to provide a detailed description of CAP mediated AFB1 degradation. We identify rapid scission of the vinyl bond between 8- and 9-position on the terminal furan ring of AFB1 as being of paramount importance for the suppression of toxic potential, which is confirmed by the examination of both cytotoxicity and genotoxicity. The plasma reactive species mediated degradation pathways are elucidated, and it is demonstrated that the approach not only renders AFB1 harmless but does so in order of magnitude less time than UV irradiation as one of the other non-thermal methods currently under investigation.

Insights into photocatalytic inactivation mechanism of the hypertoxic site in aflatoxin B1 over clew-like WO3 decorated with CdS nanoparticles

Aflatoxin B1 (AFB1) is regarded as a main biological pollutant with high toxicity, carcinogenicity and teratogenicity, and the double bond (C8C9) of its terminal furan ring is the key hypertoxic site. Although semiconductor photocatalysis has been proposed to be a potential way of reducing or inactivating the toxicity of AFB1, the reaction mechanism of reactive oxygen species with the hypertoxic site has not been defined so far. Herein, a kind of all-solid-state Z-schematic composite was fabricated by depositing CdS on the surface of clew-like WO3, which can sharply reduce the toxicity of aflatoxin B1 in aqueous solution under visible light irradiation according to the cytotoxicity test result. On the bases of high resolution mass spectrum (HRMS), radical trapping test and 18O isotope-labeling studies, it can be concluded that the preferentially inactivating the C8C9 site by the addition reaction of hydroxyl radical was the main pathway for the detoxification of aflatoxin B1. Furthermore, density functional theory (DFT) calculations were applied to reveal the reaction mechanism and verify that the hydroxyl radicals were most likely to react with the C9 site, and then form AFB1-9-hydroxy. This work provides in-depth insights into the inactivation mechanism of hypertoxic site in AFB1, and the design of efficient photocatalysts for alleviating the risk of toxic pollutants.

A Structure Identification and Toxicity Assessment of the Degradation Products of Aflatoxin B₁ in Peanut Oil under UV Irradiation.

Aflatoxins, a group of extremely hazardous compounds because of their genotoxicity and carcinogenicity to human and animals, are commonly found in many tropical and subtropical regions. Ultraviolet (UV) irradiation is proven to be an effective method to reduce or detoxify aflatoxins. However, the degradation products of aflatoxins under UV irradiation and their safety or toxicity have not been clear in practical production such as edible oil industry. In this study, the degradation products of aflatoxin B1 (AFB1) in peanut oil were analyzed by Ultra Performance Liquid Chromatograph-Thermo Quadrupole Exactive Focus mass spectrometry/mass spectrometry (UPLC-TQEF-MS/MS). The high-resolution mass spectra reflected that two main products were formed after the modification of a double bond in the terminal furan ring and the fracture of the lactone ring, while the small molecules especially nitrogen-containing compound may have participated in the photochemical reaction. According to the above results, the possible photodegradation pathway of AFB1 in peanut oil is proposed. Moreover, the human embryo hepatocytes viability assay indicated that the cell toxicity of degradation products after UV irradiation was much lower than that of AFB1, which could be attributed to the breakage of toxicological sites. These findings can provide new information for metabolic pathways and the hazard assessment of AFB1 using UV detoxification.

A Theoretical Study of 8-Chloro-9-Hydroxy-Aflatoxin B₁, the Conversion Product of Aflatoxin B₁ by Neutral Electrolyzed Water.

Theoretical studies of 8-chloro-9-hydroxy-aflatoxin B1 (2) were carried out by Density Functional Theory (DFT). This molecule is the reaction product of the treatment of aflatoxin B1 (1) with hypochlorous acid, from neutral electrolyzed water. Determination of the structural, electronic and spectroscopic properties of the reaction product allowed its theoretical characterization. In order to elucidate the formation process of 2, two reaction pathways were evaluated—the first one considering only ionic species (Cl+ and OH−) and the second one taking into account the entire hypochlorous acid molecule (HOCl). Both pathways were studied theoretically in gas and solution phases. In the first suggested pathway, the reaction involves the addition of chlorenium ion to 1 forming a non-classic carbocation assisted by anchimeric effect of the nearest aromatic system, and then a nucleophilic attack to the intermediate by the hydroxide ion. In the second studied pathway, as a first step, the attack of the double bond from the furanic moiety of 1 to the hypochlorous acid is considered, accomplishing the same non-classical carbocation, and again in the second step, a nucleophilic attack by the hydroxide ion. In order to validate both reaction pathways, the atomic charges, the highest occupied molecular orbital and the lowest unoccupied molecular orbital were obtained for both substrate and product. The corresponding data imply that the C9 atom is the more suitable site of the substrate to interact with the hydroxide ion. It was demonstrated by theoretical calculations that a vicinal and anti chlorohydrin is produced in the terminal furan ring. Data of the studied compound indicate an important reduction in the cytotoxic and genotoxic potential of the target molecule, as demonstrated previously by our research group using different in vitro assays.

Structural Analysis and Biological Toxicity of Aflatoxins B1 and B2 Degradation Products Following Detoxification by Ocimum basilicum and Cassia fistula Aqueous Extracts.

This study showed the comparison between Ocimum basilicum and Cassia fistula (leaves and branch) aqueous extracts for their ability to detoxify of aflatoxins B1 and B2 (AFB1; 100 μg L-1 and AFB2; 50 μg L-1) by In Vitro assays and decontamination studies. Results indicated that O. basilicum leaves extract was found to be highly significant (P < 0.05) in degrading AFB1 and AFB2, i.e., 90.4 and 88.6%, respectively. However, O. basilicum branch, C. fistula leaves and branch extracts proved to be less efficient in degrading these aflatoxins, under optimized conditions, i.e., pH 8, temperature 30°C and incubation period of 72 h. Moreover the antifungal activity of these plants extracts were also tested. The findings depicted that O. basilicum leaves extract showed maximum growth inhibition of aflatoxigenic isolates, i.e., 82–87% as compared to other tested plants extracts. The structural elucidation of degraded toxin products by LCMS/MS analysis showed that nine degraded products of AFB1 and AFB2 were formed. MS/MS spectra showed that most of the products were formed by the removal of double bond in the terminal furan ring and modification of lactone group indicating less toxicity as compared to parent compounds. Brine shrimps bioassay further confirmed the low toxicity of degraded products, showing that O. basilicum leaves extract can be used as an effective tool for the detoxification of aflatoxins.

Structural Elucidation and Toxicity Assessment of Degraded Products of Aflatoxin B1 and B2 by Aqueous Extracts of Trachyspermum ammi.

In this study aqueous extract of seeds and leaves of Trachyspermum ammi were evaluated for their ability to detoxify aflatoxin B1 and B2 (AFB1; 100 μg L−1 and AFB2; 50 μg L−1) by in vitro and in vivo assays. Results indicated that T. ammi seeds extract was found to be significant (P < 0.05) in degrading AFB1 and AFB2 i.e., 92.8 and 91.9% respectively. However, T. ammi leaves extract proved to be less efficient in degrading these aflatoxins, under optimized conditions i.e., pH 8, temperature 30°C and incubation period of 72 h. The structural elucidation of degraded toxin products by LCMS/MS analysis showed that eight degraded products of AFB1 and AFB2 were formed. MS/MS spectra showed that most of the products were formed by the removal of double bond in the terminal furan ring and modification of lactone group indicating less toxicity as compared to parent compounds. Brine shrimps bioassay further confirmed the low toxicity of degraded products, showing that T. ammi seeds extract can be used as an effective tool for the detoxification of aflatoxins.

Mass spectrometric identification and toxicity assessment of degraded products of aflatoxin B1 and B2 by Corymbia citriodora aqueous extracts.

This study explores the detoxification potential of Corymbia citriodora plant extracts against aflatoxin B1 and B2 (AFB1; 100 μg L−1 and AFB2; 50 μg L−1) in In vitro and In vivo assays. Detoxification was qualitatively and quantitatively analyzed by TLC and HPLC, respectively. The study was carried out by using different parameters of optimal temperature, pH and incubation time period. Results indicated that C. citriodora leaf extract(s) more effectively degrade AFB1 and AFB2 i.e. 95.21% and 92.95% respectively than C. citriodora branch extract, under optimized conditions. The structural elucidation of degraded toxin products was done by LCMS/MS analysis. Ten degraded products of AFB1 and AFB2 and their fragmentation pathways were proposed based on molecular formulas and MS/MS spectra. Toxicity of these degraded products was significantly reduced as compared to that of parent compounds because of the removal of double bond in the terminal furan ring. The biological toxicity of degraded toxin was further analyzed by brine shrimps bioassay, which showed that only 17.5% mortality in larvae was recorded as compared to untreated toxin where 92.5% mortality was observed after 96hr of incubation. Therefore, our finding suggests that C. citriodora leaf extract can be used as an effective tool for the detoxification of aflatoxins.

Degradation of aflatoxin B1 by low-temperature radio frequency plasma and degradation product elucidation

Plasma is a partially ionized gas that contains abundant free radicals and UV photons. In this work, the application of low-temperature radio frequency plasma in aflatoxin B1 (AFB1) degradation was investigated and the possible structures of the degradation products were elucidated. It was revealed that AFB1 could be effectively degraded by plasma and exposure to 300 W plasma for 10 min resulted in a degradation rate of up to 88.3 %. Kinetic analysis showed that the degradation process followed a first-order reaction and the generator power was the dominative parameter for AFB1 decomposition. Five major compounds, including 3-(hydromethyl)-8, 9-dihydro-2H-furo[2, 3-h]chromen-8-ol, 1-hydroxy-2-oxo-5-(2, 4, 6-trihydroxy-2, 3, 3a, 8a-tetrahydrofuro[2, 3-b]benzofuran-5-yl)cyclopentanecarboxylic acid, 2-(2, 4-dihydroxy-2, 3, 3a, 8a-tetrahydrofuro[2, 3-b]benzofuran-5-yl)-5-hydroxycyclopent-1-enecarboxylic acid, 1-hydroxy-2-(4-hydroxy-6-methoxy-2-oxo-2, 3, 3a, 8a-tetrahydrofuro[2, 3-b]benzofuran-5-yl)-5-oxocyclopentanecarboxylic acid, and 1, 2-dihydroxy-5-(4-hydroxy-2-oxo-2, 3, 3a, 8a-tetrahydrofuro[2, 3-b]benzofuran-5-yl)cyclopentanecarboxylic acid, were revolved and identified from the degradation product by using UPLC–Q-TOP–MS, and the addition reaction was mainly responsible for AFB1 decomposition. All the five degradation products lost their double bonds in the terminal furan ring and hence theoretically had reduced toxicity compared with AFB1 according to the structure–activity relationship. For this reason, the low-temperature radio frequency plasma is proposed potential in the decontamination of AFB1.

Analyses by UPLC Q-TOF MS of products of aflatoxin B1 after ozone treatment

Analysing the products of ozone-treated aflatoxin B1 (AFB1) is essential in order to study the practical use of ozone treatment. In this paper, the products of AFB1 were investigated using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC Q-TOF MS). The products were well separated using UPLC, and the accurate masses of all the products were determined using Q-TOF MS. Finally, the possible pathways of fragmentation ion generation from the products of AFB1 and the structures of four products were proposed. From the view of the proposed structures of products, the C8-C9 double bond in the terminal furan ring was destroyed. According to the structure–activity relationship, the toxicity of products was significantly reduced compared with that of AFB1. The result indicated that ozone was an effective agent for degrading AFB1, and UPLC Q-TOF MS was a useful analytical tool for proposing and identifying a series of unknown products.

Structure elucidation and toxicity analyses of the degradation products of aflatoxin B1 by aqueous ozone

Earlier researches showed that aflatoxin B1 (AFB1) can be effectively degraded using ozonation in the aqueous systems. However, the degradation products have not been identified until today. In this article, the degradation products of AFB1 were analyzed using ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometers (UPLC Q-TOF MS). Under our experimental conditions, six key degradation product structures and possible paths for generating fragment ions were proposed. The proposals were based on the low mass error, high match rate in degradation product speculation, and possible molecular formulas that could be obtained using UPLC Q-TOF MS. UPLC revealed the existence of degradation products, whereas Q-TOF MS exposed the structures of the fragment ions for AFB1 and its degradation products. Due to the conjugate addition reaction on the double bond of the terminal furan ring for AFB1, the toxicity of the degradation products was significantly decreased compared with that of AFB1 through the toxicity analysis of the degradation products according to the structure–activity relationship. The results showed that aqueous ozone treatment was an effective method for degrading AFB1.

Structures of the Ozonolysis Products and Ozonolysis Pathway of Aflatoxin B1 in Acetonitrile Solution

The ozonolysis of aflatoxin B(1) (400 μg/mL) in acetonitrile solution was conducted with an ozone concentration of 6.28 mg/L at the flow rate of 60 mL/min for different times. The results showed that ozone was an effective detoxification agent because of its powerful oxidative role. Thin-layer chromatography and liquid chromatography-quadrupole time-of-flight mass spectra were applied to confirm and identify the ozonolysis products of aflatoxin B(1). A total of 13 products were identified, and 6 of them were main products. The structural identification of these products provided effective information for understanding the ozonolysis pathway of aflatoxin B(1). Two ozonolysis pathways were proposed on the basis of the accurate mass and molecular formulas of these product ions. Nine ozonolysis products came from the first oxidative pathway based on the Criegee mechanism, and the other four products were produced from the second pathway based on the oxidative and electrophilic reactions of ozone. According to the toxicity mechanism of aflatoxin B(1) to animals, the toxicity of aflatoxin B(1) was significantly reduced because of the disappearance of the double bond on the terminal furan ring or the lactone moiety on the benzene ring.

Structure elucidation and toxicity analyses of the radiolytic products of aflatoxin B 1 in methanol–water solution

The identification of the radiolytic products of mycotoxins is a key issue in the feasibility study of gamma ray radiation detoxification. Methanol–water solution (60:40, v/v) spiked with aflatoxin B 1 (AFB 1; 20 mg L −1) was irradiated with Co 60 gamma ray to generate radiolytic products. Liquid chromatography–quadruple time-of-flight mass spectrometry was applied to identify the radiolytic products of AFB 1. Accurate mass and proposed molecular formulas with a high-matching property of more than 20 radiolytic products were obtained. Seven key radiolytic products were proposed based on the molecular formulas and tandem mass spectrometry spectra. The analyses of toxicity and formation pathways were proposed based on the structure of the radiolytic products. The addition reaction caused by the free-radical species in the methanol–water solution resulted in the formation of most radiolytic products. Based on the structure–activity relationship analysis, the toxicity of radiolytic products was significantly reduced compared with that of AFB 1 because of the addition reaction that occurred on the double bond in the terminal furan ring. For this reason, gamma irradiation is deemed an effective tool for the detoxification of AFB 1.