In vitro genotoxicity of mycotoxins ochratoxin A and fumonisin B1 could be prevented by sodium copper chlorophyllin – Implication to their genotoxic mechanism

Investigation of the Genotoxic Potential of the Marine Toxin C17-SAMT Using the In Vivo Comet and Micronucleus Assays

The contaminant responsible for the atypical toxicity reported in mussels from Bizerte Lagoon (Northern Tunisia) during the last decade has been characterized as C17-sphinganine analog mycotoxin (C17-SAMT). This neurotoxin showed common mouse toxic symptoms, including flaccid paralysis and severe dyspnea, followed by rapid death. For hazard assessment on human health, in this work we aimed to evaluate the in vivo genotoxic effects of this marine biotoxin using the classical alkaline and modified Fpg comet assays performed to detect DNA breaks and alkali-labile sites as well as oxidized bases. The micronucleus assay was used on bone marrow to detect chromosome and genome damage. C17-SAMT induces a statistically insignificant increase in DNA tail intensity at all doses in the duodenum, and in the spleen contrary to the liver, the percentage of tail DNA increased significantly at the mid dose of 300 µg/kg b.w/d. C17-SAMT did not affect the number of micronuclei in the bone marrow. Microscopic observations of the liver showed an increase in the number of mitosis and hepatocytes' cytoplasm clarification. At this level of study, we confirm that C17-SAMT induced DNA damage in the liver but there was no evidence of effects causing DNA oxidation or chromosome and genome damage.

Express high-sensitive detection of ochratoxin A in food by a lateral flow immunoassay based on magnetic biolabels

We present an easy-to-use lateral flow immunoassay for rapid, precise and sensitive quantification of one of the most hazardous mycotoxins - ochratoxin A (OTA), which is widely present in food and agricultural commodities. The achieved limit of detection during the 20-min OTA registration is 11 pg/mL. The assay provides accurate results in both low- and high-concentration ranges. That is due to the extraordinary steepness of the linear calibration plot: 5-order dynamic range of concentrations causes almost a 1000-fold change in the signal obtained by electronic detection of magnetic biolabels using their non-linear magnetization. High specificity, repeatability, and reproducibility of the assay have been verified, including measuring OTA in real samples of contaminated corn flour. The developed assay is a promising analytical tool for food and feed safety control; it may become an express, convenient and high-precision alternative to the traditional sophisticated laboratory techniques based on liquid chromatography.

Relationship between lifespan and somatic mutation in D. melanogaster after treatment with chlorophyllin

Sodium copper chlorophyllin (SCC) has a genetic damage inhibitory capacity due to its antioxidant action. For this reason, it was considered to investigate its role in the life span of Drosophila melanogaster and its relationship with the frequency of somatic mutation induced by gamma rays. Results indicated that SCC alone prolonged the lifespan only in females, but in combination with 20 Gy of gamma rays, the aging delay in both sexes was significant. In addition to confirming that the porphyrin reduces the frequency of mutation, the individuals with the highest mutation load are the individuals who die more quickly, and once they are eliminated, the survivor individuals treated with 20 Gy or with SCC + 20 Gy, died at the same rate. The results together indicate that SCC not only inhibits induced genetic damage, but it also has beneficial effects that probably cause an aging delay of the treated population that need to be investigated.

Genotoxic effects of the ochratoxin A (OTA), its main metabolite (OTα) per se and in combination with fumonisin B1 in HepG2 cells and human lymphocytes

Ochratoxin A (OTA) and fumonisin B₁ (FB₁) are mycotoxins distributed in a wide variety of foods for human or animal consumption and are classified as possible carcinogens for humans. This study aimed to evaluate the cytotoxic, cytostatic and genotoxic effects of OTA and its main metabolite, ochratoxin α (OTα), FB₁ and three combinations of OTA and FB₁ at moderate and environmental doses. Cell viability was evaluated through MTT assay and the trypan blue exclusion method. The cytostatic and genotoxic effects were evaluated through the cytokinesis-block micronucleus assay. The results showed synergistic time- and concentration-dependent cytotoxic effects of one of the combinations of OTA and FB₁. In contrast, significant differences were observed in the micronuclei (MN) frequency from OTA, OTα and coexposure of OTA + FB₁. Some of these combinations increased the frequency of nuclear buds, nucleoplasmic bridges, donut-shaped nuclei, necrotic and apoptotic cells and MN in mononucleated cells. In conclusion, OTA and its main metabolite OTα, as well as the co-exposure of OTA and FB₁, cause stable DNA damage at environmentally relevant concentrations, which was greater in metabolically competent cells. More studies are needed to understand the chemical interactions that occur due to the joint presence of mycotoxins, which occurs commonly.

Toxic Mechanism and Biological Detoxification of Fumonisins

Food safety is related to the national economy and people’s livelihood. Fumonisins are widely found in animal feed, feed raw materials, and human food. This can not only cause economic losses in animal husbandry but can also have carcinogenicity or teratogenicity and can be left in animal meat, eggs, and milk which may enter the human body and pose a serious threat to human health. Although there are many strategies to prevent fumonisins from entering the food chain, the traditional physical and chemical methods of mycotoxin removal have some disadvantages, such as an unstable effect, large nutrient loss, impact on the palatability of feed, and difficulty in mass production. As a safe, efficient, and environmentally friendly detoxification technology, biological detoxification attracts more and more attention from researchers and is gradually becoming an accepted technique. This work summarizes the toxic mechanism of fumonisins and highlights the advances of fumonisins in the detoxification of biological antioxidants, antagonistic microorganisms, and degradation mechanisms. Finally, the future challenges and focus of the biological control and degradation of fumonisins are discussed.

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.

Genotoxicity of three mycotoxin contaminants of rice: 28-day multi-endpoint assessment in rats

Deoxynivalenol (DON), zearalenone (ZEN), and fumonisin B₁ (FB₁), as the main mycotoxins contaminating rice, often coexist in food. Thus, we have measured the genotoxicity of the three rice fungal contaminants, singly and in different combinations, with a 28-day multi-endpoint (Pig-a assay + in vivo micronucleus [MN] test + comet assay) genotoxicity platform. Male Sprague-Dawley rats received the agents orally via gavage for 28 consecutive days, before performing the abovementioned tests. Results indicated that low dose of a single mycotoxin did not show significant genotoxicity. However, some of these mycotoxins in combination induced significant genotoxicity in the peripheral blood and tissues, at sacrifice. In the peripheral blood, the binary combination of DON and FB₁ significantly induced MN. In the liver, ZEN might aggravate the DNA-damaging effects of DON and FB₁. Therefore, the genotoxicity of sub-chronic exposure to mycotoxins in combination cannot be ignored.

A novel qPCR based-method for detection and quantification of three recurrent species of Penicillium isolated from bioaerosols in mold-damaged homes

Fungal contamination of indoor environments can cause respiratory diseases and induce damages to building materials. Among the fungal species found in mold-damaged homes, Penicillium brevicompactum, P. chrysogenum and P. crustosum can be considered as recurrent strains. In this study, we therefore propose a rapid and novel qPCR-based method in order to allow the monitoring of these three fungal species. The method developed allows the quantification of the target DNA of these three Penicillium species with a limit of quantification of 0.01 ng/μL without significant difference with spectrophotometry quantification assay for DNA concentrations between 5 and 100 ng/μL. This technique also enables the rapid detection of these three species in complex mixtures of DNA extracted from 15 bioaerosols collected in mold-damaged homes and previously cultured on agar plate. This new sensitive and specific qPCR technique can thus be easily integrated into bioaerosol studies.

Aspergillus derived mycotoxins in food and the environment: Prevalence, detection, and toxicity

Aspergillus species are the paramount ubiquitous fungi that contaminate various food substrates and produce biochemicals known as mycotoxins. Aflatoxins (AFTs), ochratoxin A (OTA), patulin (PAT), citrinin (CIT), aflatrem (AT), secalonic acids (SA), cyclopiazonic acid (CPA), terrein (TR), sterigmatocystin (ST) and gliotoxin (GT), and other toxins produced by species of Aspergillus plays a major role in food and human health. Mycotoxins exhibited wide range of toxicity to the humans and animal models even at nanomolar (nM) concentration. Consumption of detrimental mycotoxins adulterated foodstuffs affects human and animal health even trace amounts. Bioaerosols consisting of spores and hyphal fragments are active elicitors of bronchial irritation and allergy, and challenging to the public health. Aspergillus is the furthermost predominant environmental contaminant unswervingly defile lives with a 40-90 % mortality risk in patients with conceded immunity. Genomics, proteomics, transcriptomics, and metabolomics approaches useful for mycotoxins' detection which are expensive. Antibody based detection of toxins chemotypes may result in cross-reactivity and uncertainty. Aptamers (APT) are single stranded DNA (ssDNA/RNA), are specifically binds to the target molecules can be generated by systematic evolution of ligands through exponential enrichment (SELEX). APT are fast, sensitive, simple, in-expensive, and field-deployable rapid point of care (POC) detection of toxins, and a better alternative to antibodies.

In Situ Synthesis of a Double-Layer Chitosan Coating on Cotton Fabric to Improve the Color Fastness of Sodium Copper Chlorophyllin

Natural dye's poor affinity for cotton and poor fastness properties still hinder its applications in the textile industry. In this study, a doubled-layered chitosan coating was cured on cotton fabric to serve as bio-mordant and form a protective layer on it. Under the optimal treatment conditions, the maximum qe (adsorption amount) of the natural dye sodium copper chlorophyllin (SCC) calculated from the Langmuir isothermal model was raised from 4.5 g/kg to 19.8 g/kg. The dye uptake of the treated fabric was improved from 22.7% to 96.4% at 1% o.w.f. dye concentration. By a second chitosan layer cured on the dyed fabric via the cross-linking method, the wash fastness of the cotton fabric dyed with SCC can be improved from 3 to 5 (ISO 105 C-06). The natural source of the biopolymer material, chitosan, and its ability to biodegrade at end of life met with the initial objective of green manufacturing in applying natural dyes and natural materials to the textile industry.

Cytoprotective effects of curcumin and silymarin on PK-15 cells exposed to ochratoxin A, fumonisin B1 and deoxynivalenol

Mycotoxins are toxic secondary metabolites produced by fungus which cause worldwide concern regarding food and feed safety. Ochratoxin A (OTA), fumonisin B₁ (FB₁) and deoxynivalenol (DON) are some of the main mycotoxins and oxidative stress is the main mechanism of toxicity. Thereby, this study investigates the in vitro cytoprotective effects of curcumin (CUR) and silymarin (SIL) - known for their strong antioxidant activity - in PK-15 cells exposed to OTA, FB₁ and DON. Pretreatment with CUR and SIL enhanced the viability of cells exposed to the mycotoxins (P < 0.001) and attenuated reactive oxygen species (ROS) formation by DON (P < 0.01), partially reduced ROS formation by FB₁ (P < 0.001), but not OTA. CUR significantly decreased apoptosis in cells exposed to DON (P < 0.01) but was not able to prevent apoptosis in cells exposed to OTA and FB₁. Whereas SIL was able to prevent apoptosis in PK-15 cells exposed to FB₁ and DON (P < 0.01) but was not able to decrease apoptosis in cells exposed to OTA. In summary, these data indicate that curcumin and silymarin are able to provide cytoprotection against toxicity induced by OTA, FB₁ and DON in PK-15 cells.

Fumonisin B1 induces toxicity in human leukocytes at low concentrations: Are computational studies effective to determine biosafety?

Fumonisin B₁ is a mycotoxin produced by Fusarium verticillioides and Fusarium proliferatum found in various crops, particularly maize. Besides carcinogenicity, other manifestations have been registered in different animals and in humans. In the case of humans, epidemiological studies have reported high prevalence of esophageal cancer in populations exposed to fumonisins. This study aimed to evaluate the minimum concentration of FB₁ capable of inducing cytotoxicity (cell viability test), genotoxicity (comet assay) and mutagenicity (micronucleus) in cultured human leukocytes and to evaluate the effectiveness of in silico tests to predict FB₁ toxicity. All concentrations analyzed (200; 100; 50; 5; 0.5; 0.05; 0.005 μg/mL and 300; 30; 3; 1; 0.1; 0.01 fg/mL) except the lowest demonstrated dose-dependent toxicity in all parameters analyzed (p < 0.05 to p < 0.0001). As for predictions, only the Lazar software showed carcinogenicity of FB₁ for rats. Thus, it is evident that FB₁ is able to induce dose-dependent damage at low concentrations, and that computational tests, although desirable for prediction, are not effective as biological tests to determine toxicity, at least of FB ₁ and within the experimental conditions tested.

Genotoxic effects of mycotoxins

Fungi produce mycotoxins in the presence of appropriate temperature, humidity, sufficient nutrients and if the density of the mushroom mass is favorable. Although all mycotoxins are of fungal origin, all toxic compounds produced by fungi are not called mycotoxins. The interest in mycotoxins first started in the 1960s, and today the interest in mycotoxin-induced diseases has increased. To date, 400 mycotoxins have been identified and the most important species producing mycotoxins belongs to Aspergillus, Penicillium, Alternaria and Fusarium genera. Mycotoxins are classified as hepatotoxins, nephrotoxins, neurotoxins, immunotoxins etc. In this review genotoxic and also other health effects of some major mycotoxin groups like Aflatoxins, Ochratoxins, Patulin, Fumonisins, Zearalenone, Trichothecenes and Ergot alkaloids were deeply analyzed.

Fumonisin-(Fusarium verticillioides)-contaminated feed causes hepatic oxidative stress and negatively affects broiler performance in the early stage: Does supplementation with açai flour residues (Euterpe oleracea) minimize these problems?

Fusarium verticillioides is often responsible for contamination of poultry feed with the mycotoxin fumonisin. The aim of this study was to determine whether oxidative stress caused by intake of fumonisin-contaminated feed affects broiler performance at an early stage of development, as well as to test whether the addition of açai residue flour to contaminated feed would minimize these negative effects of redox metabolism. Birds were divided into four groups, with four repetitions of five animals each: control (TC) - birds that received basal feed; TCA treatment - basal feed supplemented with 2% açai flour; TF treatment - feed experimentally contaminated with fumonisin (10 ppm); TFA treatment - fumonisin-contaminated feed (10 ppm) and supplemented with açai fluor (2%). The experiment lasted 20 days, that is, the first 20 days of the chicks' lives. At the end of the experiment, the birds were weighed, and blood, intestine and liver samples were collected. The TCA and TFA had greater body weights and weight gain than did TF. Further, TCA and TFA had lower feed conversion than did TF. Açai flour intake (TCA and TFA) stimulated albumin synthesis and reduced serum AST activity. Nitrate/nitrite (NOx) levels were higher in serum of fumonisin-challenged (TF) birds than in groups; NOx levels were also higher in the livers of all test groups (TF, TCA and TFA) than in TC. Serum glutathione S-transferase (GST) activity was lower in fumonisin-consuming groups (TF and TFA); this was different from what occurred in the liver, that is, higher GST activity in TF and lower activity in TFA than in TC. Catalase activity (CAT) was also higher in the fumonisin-challenged groups (TF and TFA) and the groups supplemented with açai flour (TCA) than in TC. Serum reactive species (RS) and TBARS (lipid peroxidation) levels in the liver were lower in birds supplemented with açai flour and exposed to fumonisin. These data suggest that the addition of açai flour in the feed of early chickens improves animal performance and minimizes the effects of hepatic oxidative stress in birds fed fumonisin-contaminated feed.

Risk assessment of ochratoxin A in food

The European Commission asked EFSA to update their 2006 opinion on ochratoxin A (OTA) in food. OTA is produced by fungi of the genus Aspergillus and Penicillium and found as a contaminant in various foods. OTA causes kidney toxicity in different animal species and kidney tumours in rodents. OTA is genotoxic both in vitro and in vivo; however, the mechanisms of genotoxicity are unclear. Direct and indirect genotoxic and non-genotoxic modes of action might each contribute to tumour formation. Since recent studies have raised uncertainty regarding the mode of action for kidney carcinogenicity, it is inappropriate to establish a health-based guidance value (HBGV) and a margin of exposure (MOE) approach was applied. For the characterisation of non-neoplastic effects, a BMDL 10 of 4.73 μg/kg body weight (bw) per day was calculated from kidney lesions observed in pigs. For characterisation of neoplastic effects, a BMDL 10 of 14.5 μg/kg bw per day was calculated from kidney tumours seen in rats. The estimation of chronic dietary exposure resulted in mean and 95th percentile levels ranging from 0.6 to 17.8 and from 2.4 to 51.7 ng/kg bw per day, respectively. Median OTA exposures in breastfed infants ranged from 1.7 to 2.6 ng/kg bw per day, 95th percentile exposures from 5.6 to 8.5 ng/kg bw per day in average/high breast milk consuming infants, respectively. Comparison of exposures with the BMDL 10 based on the non-neoplastic endpoint resulted in MOEs of more than 200 in most consumer groups, indicating a low health concern with the exception of MOEs for high consumers in the younger age groups, indicating a possible health concern. When compared with the BMDL 10 based on the neoplastic endpoint, MOEs were lower than 10,000 for almost all exposure scenarios, including breastfed infants. This would indicate a possible health concern if genotoxicity is direct. Uncertainty in this assessment is high and risk may be overestimated.

UHPLC-ToF-MS method for determination of multi-mycotoxins in maize: Development and validation

An Ultra-High Performance Liquid Chromatography combined with Time-of-Flight Mass Spectrometry (UHPLC–ToF-MS) method has been developed for determination of nine mycotoxins, namely aflatoxins (AFB₁, AFB₂, AFG₁ and AFG₂), ochratoxin A (OTA), zearalenone (ZEA), toxin T2 (T2) and fumonisins (FB₁ and FB₂) in maize. The method included a two-step extraction with acetonitrile 80% (v/v). After optimization, the analytical method was validated. The different concentrations tested take in account the Maximum Levels (ML) for maize (Commission Regulation EC no. 1881/2006) and good results for repeatability (%RSD_r ≤ 15.4%), reproducibility (%RSD_R ≤ 15.9%) and recovery (77.8–110.4%, except for AFG2 at 2 μg/kg which presented a recovery of 73.4%) were achieved. These met the performance criteria imposed by Commission Regulation (EC) no. 401/2006. The method was applied to twenty-two samples from Portuguese producers of maize. Fumonisins were the most frequently detected mycotoxins, but the levels do not exceed those imposed by European legislation.

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A UHPLC–ToF-MS method was developed for determination of nine mycotoxins in maize.

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Validation of the method was performed taking in account the EU maximum legal limits for maize.

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Good results for repeatability, reproducibility and recovery were achieved.

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The method was applied to 22 samples from Portuguese producers of maize.

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Fumonisins were the most frequently detected mycotoxins.

Esophageal cancer in Mozambique: should mycotoxins be a concern?

Fumonisin B1 (FB1) is a mycotoxin frequently found in agricultural commodities. The toxin poses a considerable risk for human and animal health. FB1 is among several mycotoxins produced by Fusarium spp. contaminating virtually any cereal and other Poaceae. Their intracellular action includes the promotion of oxidative stress through the generation of reactive oxygen species (ROS) that damage biomolecules such as DNA. These toxic effects were observed in vivo and in vitro. However, the association between esophageal lesions and oxidative stress induced by FB1. Studies in China, Iran and South Africa showed higher exposure to fumonisins in areas with higher risk of esophageal cancer (EC). Exposure to mycotoxins may be inevitable in Mozambique. How mycotoxins, particularly fumonisins from the contaminated food, can be associated with the emergence of EC in Mozambique? Herein, we revise the literature and present some pieces of evidence in order to highlight the burden of mycotoxins and to provide evidence-based considerations for the stakeholders involved in the management of the EC agenda in Mozambique. The information presented herein supports the need to implement novel and/or to revisit the existent detoxification methods to reduce the global burden of mycotoxins and its outcomes in health management.

Radioprotective properties of food colorant sodium copper chlorophyllin on human peripheral blood cells in vitro

Sodium copper chlorophyllin (CHL) is a food colorant that exhibits many beneficial properties, including potential for use in radiotherapy. Nevertheless, genotoxicity studies investigating radioprotective properties against γ-radiation on human cells are rather scarce. The aim of this study was to assess the cytotoxicity, genotoxicity and induction of malondialdehyde formation on CHL pre-treated whole blood cells after an absorbed dose of 5 Gy γ-radiation. Irradiated whole blood cells pre-treated with 100, 500, and 1000 μg/mL CHL showed less DNA-strand breaks (10.92 ± 0.74%, 10.69 ± 0.68%, and 8.81 ± 0.69%, respectively) than untreated irradiated cells (12.58 ± 0.88%). At the same time, the level of malondialdehyde was lower in CHL pre-treated samples with 100, 500, and 1000 μg/mL CHL (14.11 ± 0.43, 16.35 ± 2.82, and 13.08 ± 1.03 μmol/L, respectively) compared to untreated irradiated samples (24.11 ± 0.25 μmol/L). Regarding cytotoxicity, no changes were observed in the samples tested. Another important finding is that CHL had no cyto/genotoxic properties toward human blood cells. Taken together, since CHL had no cyto/genotoxic effects and showed good radioprotective properties in human blood cells, further studies should be conducted in order to find its possible application in radiotherapy.

Phytic Acid Decreases Oxidative Stress and Intestinal Lesions Induced by Fumonisin B₁ and Deoxynivalenol in Intestinal Explants of Pigs

The purpose of the present study was to investigate the effects of phytic acid (IP6) on morphological and immunohistochemical parameters and oxidative stress response in intestinal explants of pigs exposed to fumonisin B₁ (FB₁) and/or deoxynivalenol (DON). The jejunal explants were exposed to the following treatments: vehicle, IP6 5 mM, DON 10 µM, FB₁ 70 µM, DON 10 µM + FB₁ 70 µM, DON 10 µM + IP6 5 mM, FB₁ 70 µM + IP6 5 mM, and DON 10 µM + FB₁ 70 µM + IP6 5 mM. The decrease in villus height and goblet cell density was more evident in DON and DON + FB₁ treatments. In addition, a significant increase in cell apoptosis and cell proliferation and a decrease in E-cadherin expression were observed in the same groups. DON and FB₁ exposure increased cyclooxygenase-2 expression and decreased the cellular antioxidant capacity. An increase in lipid peroxidation was observed in DON- and FB₁-treated groups. IP6 showed beneficial effects, such as a reduction in intestinal morphological changes, cell apoptosis, cell proliferation, and cyclooxygenase-2 expression, and an increase in E-cadherin expression when compared with DON, FB₁ alone, or DON and FB₁ in association. IP6 inhibited oxidative stress and increased the antioxidant capacity in the explants exposed to mycotoxins.

Mycotoxins and oxidative stress: where are we?

Mycotoxins are the most common contaminants of food and feed worldwide and are considered an important risk factor for human and animal health. Oxidative stress occurs in cells when the concentration of reactive oxygen species exceeds the cell’s antioxidant capacity. Oxidative stress causes DNA damage, enhances lipid peroxidation, protein damage and cell death. This review addresses the toxicity of the major mycotoxins, especially aflatoxin B1, deoxynivalenol, nivalenol, T-2 toxin, fumonisin B1, ochratoxin, patulin and zearalenone, in relation to oxidative stress. It summarises the data associated with oxidative stress as a plausible mechanism for mycotoxin-induced toxicity. Given the contamination caused by mycotoxins worldwide, the protective effects of a variety of natural compounds due to their antioxidant capacities have been evaluated. We review data on the ability of vitamins, flavonoids, crocin, curcumin, green tea, lycopene, phytic acid, L-carnitine, melatonin, minerals and mixtures of anti-oxidants to mitigate the toxic effect of mycotoxins associated with oxidative stress.

Appropriateness to set a group health-based guidance value for fumonisins and their modified forms

The EFSA Panel on Contaminants in the Food Chain (CONTAM) established a tolerable daily intake (TDI) for fumonisin B1 (FB 1) of 1.0 μg/kg body weight (bw) per day based on increased incidence of megalocytic hepatocytes found in a chronic study with mice. The CONTAM Panel considered the limited data available on toxicity and mode of action and structural similarities of FB 2-6 and found it appropriate to include FB 2, FB 3 and FB 4 in a group TDI with FB 1. Modified forms of FBs are phase I and phase II metabolites formed in fungi, infested plants or farm animals. Modified forms also arise from food or feed processing, and include covalent adducts with matrix constituents. Non-covalently bound forms are not considered as modified forms. Modified forms of FBs identified are hydrolysed FB 1-4 (HFB 1-4), partially hydrolysed FB 1-2 (pHFB 1-2), N-(carboxymethyl)-FB 1-3 (NCM-FB 1-3), N-(1-deoxy-d-fructos-1-yl)-FB 1 (NDF-FB 1), O-fatty acyl FB 1, N-fatty acyl FB 1 and N-palmitoyl-HFB 1. HFB 1, pHFB 1, NCM-FB 1 and NDF-FB 1 show a similar toxicological profile but are less potent than FB 1. Although in vitro data shows that N-fatty acyl FBs are more toxic in vitro than FB 1, no in vivo data were available for N-fatty acyl FBs and O-fatty acyl FBs. The CONTAM Panel concluded that it was not appropriate to include modified FBs in the group TDI for FB 1-4. The uncertainty associated with the present assessment is high, but could be reduced provided more data are made available on occurrence, toxicokinetics and toxicity of FB 2-6 and modified forms of FB 1-4.

Nonlinear optical properties of sodium copper chlorophyllin in aqueous solution

Background

Sodium copper chlorophyllin (SCC), as one of the derivatives of chlorophyll – with its inherent green features; good stability for heat, light, acids and alkalies; unique antimicrobial capability; and particular deodorization performance – is widely applied in some fields such as the food industry, medicine and health care, daily cosmetic industry etc. SCC, as one of the metal porphyrins, has attracted much attention because of its unique electronic band structure and photon conversion performance. To promote the application of SCC in materials science; energy research and photonics, such as fast optical communications; and its use in nonlinear optical materials, solar photovoltaic cells, all-optical switches, optical limiters and saturable absorbers, great efforts should be dedicated to studying its nonlinear optical (NLO) properties.

Methods

In this study, the absorption spectra and NLO properties of SCC in aqueous solution at different concentrations were measured. The Z-scan technique was used to determine NLO properties.

Results

The results indicated that the absorption spectra of SCC exhibit 2 characteristic absorption peaks located at the wavelengths 405 and 630 nm, and the values of the peaks increase with increasing SCC concentration. The results also showed that SCC exhibits reverse saturation absorption and negative nonlinear refraction (self-defocusing).

Conclusions

It can be seen that SCC has good optical nonlinearity which will be convenient for applications in materials science, energy research and photonics.

Oxidative stress response in canine in vitro liver, kidney and intestinal models with seven potential dietary ingredients

In vitro cell culture systems are a useful tool to rapidly assess the potential safety or toxicity of chemical constituents of food. Here, we investigated oxidative stress and organ-specific antioxidant responses by 7 potential dietary ingredients using canine in vitro culture of hepatocytes, proximal tubule cells (CPTC), bone marrow-derived mesenchymal stem cells (BMSC) and enterocyte-like cells (ELC). Cellular production of free radical species by denatonium benzoate (DB), epigallocatechin gallate (EPI), eucalyptol (EUC), green tea catechin extract (GTE) and sodium copper chlorophyllin (SCC), tetrahydroisohumulone (TRA) as well as xylitol (XYL) were continuously measured for reactive oxygen/nitrogen species (ROS/RNS) and superoxide (SO) for up to 24h. DB and TRA showed strong prooxidant activities in hepatocytes and to a lesser degree in ELC. DB was a weak prooxidant in BMSC. In contrast DB and TRA were antioxidants in CPTC. EPI was prooxidant in hepatocytes and BMSC but showed prooxidant and antioxidant activity in CPTC. SCC in hepatocytes (12.5mg/mL) and CPTC (0.78mg/mL) showed strong prooxidant and antioxidant activity in a concentration-dependent manner. GTE was effective antioxidant only in ELC. EUC and XYL did not induce ROS/RNS in all 4 cell types. SO production by EPI and TRA increased in hepatocytes but decreased by SCC in hepatocytes and ELC. These results suggest that organ-specific responses to oxidative stress by these potential prooxidant compounds may implicate a mechanism of their toxicities.

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.

Label-Free Luminescent Switch-On Probe for Ochratoxin A Detection Using a G-Quadruplex-Selective Iridium(III) Complex

A library of six luminescent Ir(III) complexes were synthesized and studied for their capacity to function as probes for G-quadruplex DNA. The novel Ir(III) complex 1 was discovered to be selective for G-quadruplex structures and was subsequently used for the construction of a label-free G-quadruplex-based ochratoxin A (OTA) sensing platform in aqueous solution. The assay exhibited linearity for OTA in the range of 0 to 60 nM (R2=0.9933), and the limit of detection for OTA was 5 nM. Furthermore, this assay was highly selective for OTA over its structurally related analogues.