DNA damage in human fibroblasts exposed to fumonisin B(1)

The role of chromatin-modifying enzymes and histone modifications in the modulation of p16 gene in fumonisin B1-induced toxicity in human kidney cells

Fumonisin B₁ (FB₁) poses a risk to animal and human health. Although the effects of FB₁ on sphingolipid metabolism are well documented, there are limited studies covering the epigenetic modifications and early molecular alterations associated with carcinogenesis pathways caused by FB₁ nephrotoxicity. The present study investigates the effects of FB₁ on global DNA methylation, chromatin-modifying enzymes, and histone modification levels of the p16 gene in human kidney cells (HK-2) after 24 h exposure. An increase (2.23-fold) in the levels of 5-methylcytosine (5-mC) at 100 µmol/L was observed, a change independent from the decrease in gene expression levels of DNA methyltransferase 1 (DNMT1) at 50 and 100 µmol/L; however, DNMT3a and DNMT3b were significantly upregulated at 100 µmol/L of FB₁. Dose-dependent downregulation of chromatin-modifying genes was observed after FB₁ exposure. In addition, chromatin immunoprecipitation results showed that 10 µmol/L of FB₁ induced a significant decrease in H3K9ac, H3K9me3 and H3K27me3 modifications of p16, while 100 µmol/L of FB₁ caused a significant increase in H3K27me3 levels of p16. Taken together, the results suggest that epigenetic mechanisms might play a role in FB₁ carcinogenesis through DNA methylation, and histone and chromatin modifications.

Food-Borne Chemical Carcinogens and the Evidence for Human Cancer Risk

Commonly consumed foods and beverages can contain chemicals with reported carcinogenic activity in rodent models. Moreover, exposures to some of these substances have been associated with increased cancer risks in humans. Food-borne carcinogens span a range of chemical classes and can arise from natural or anthropogenic sources, as well as form endogenously. Important considerations include the mechanism(s) of action (MoA), their relevance to human biology, and the level of exposure in diet. The MoAs of carcinogens have been classified as either DNA-reactive (genotoxic), involving covalent reaction with nuclear DNA, or epigenetic, involving molecular and cellular effects other than DNA reactivity. Carcinogens are generally present in food at low levels, resulting in low daily intakes, although there are some exceptions. Carcinogens of the DNA-reactive type produce effects at lower dosages than epigenetic carcinogens. Several food-related DNA-reactive carcinogens, including aflatoxins, aristolochic acid, benzene, benzo[a]pyrene and ethylene oxide, are recognized by the International Agency for Research on Cancer (IARC) as causes of human cancer. Of the epigenetic type, the only carcinogen considered to be associated with increased cancer in humans, although not from low-level food exposure, is dioxin (TCDD). Thus, DNA-reactive carcinogens in food represent a much greater risk than epigenetic carcinogens.

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.

Fumonisin B1 exposure deteriorates oocyte quality by inducing organelle dysfunction and DNA damage in mice

Oocyte quality is critical for fertilization and early embryo development. Fumonisin B1 (FB1) is a Fusarium mycotoxin and it is commonly found in contaminated food and feedstuff, posing a potential health hazard to both animals and human. FB1 is reported to have hepatotoxicity, neurotoxicity, nephrotoxicity, immunotoxicity and embryotoxicity. However, the effects of FB1 on mouse oocyte quality are still unknown. Here, we explored the toxic effects and potential mechanisms of FB1 on oocyte maturation quality in mice. FB1 exposure inhibited the first polar body extrusion at concentrations of 30 μM and 50 μM, which further induced oocyte meiotic arrest. Besides, disrupted spindle structure was found in oocytes after FB1 exposure. Our results also showed that FB1 exposure impaired mitochondria dysfunction, which further induced oxidative stress and early apoptosis. In addition, we reported that FB1 exposure induced the accumulation of lysosome and occurrence of autophagy. Aberrant ER distribution and ER stress were also found in FB1-exposed oocytes. Moreover, DNA damage was also observed. These results together suggested that FB1 exposure affected oocyte quality by destroying spindle structure, leading to mitochondria, lysosome and ER dysfunction, which further induced oxidative stress, apoptosis, autophagy and DNA damage in mouse oocytes.

Molecular and epigenetic modes of Fumonisin B1 mediated toxicity and carcinogenesis and detoxification strategies

Fumonisin B₁ (FB₁) is a natural contaminant of agricultural commodities that has displayed a myriad of toxicities in animals. Moreover, it is known to be a hepatorenal carcinogen in rodents and may be associated with oesophageal and hepatocellular carcinomas in humans. The most well elucidated mode of FB₁-mediated toxicity is its disruption of sphingolipid metabolism; however, enhanced oxidative stress, endoplasmic reticulum stress, autophagy, and alterations in immune response may also play a role in its toxicity and carcinogenicity. Alterations to the host epigenome may impact on the toxic and carcinogenic response to FB₁. Seeing that the contamination of FB₁ in food poses a considerable risk to human and animal health, a great deal of research has focused on new methods to prevent and attenuate FB₁-induced toxic consequences. The focus of the present review is on the molecular and epigenetic interactions of FB₁ as well as recent research involving FB₁ detoxification.

Fumonisin B1 exposure adversely affects porcine oocyte maturation in vitro by inducing mitochondrial dysfunction and oxidative stress

Fumonisin B₁ (FB₁), as the most toxic fumonisin, is a common Fusarium mycotoxin contaminant of feed stuff and food, posing a potential health hazard to animals and humans. FB₁ has been reported to cause hepatotoxicity, neurotoxicity, nephrotoxicity, immunotoxicity and embryotoxicity; however, little information is available on whether FB₁ has toxic effects on mammalian oocytes. Herein, we adopted porcine oocytes as models to explore the effects and potential mechanisms of FB₁ on mammalian oocytes during in vitro maturation. Porcine cumulus oocyte complexes (COCs) were exposed to 0, 20, 30 and 40 μM FB₁ for 44 h during in vitro maturation, and the results reported that first polar body (PB1) extrusion was significantly inhibited when the FB₁ concentration reached 30 (P < 0.01) or 40 μM (P < 0.001). Further cell cycle analysis revealed that meiotic progression was disrupted, with a larger proportion of the 30 μM FB₁-treated oocytes being arrested at the germinal vesicle breakdown (GVBD) stage (P < 0.01). After being treated with 30 μM FB₁ for 28 h, the percentage of oocytes with aberrant spindle assembly was observably increased (P < 0.01), and the distribution of actin filaments on the plasma membrane was significantly reduced (P < 0.05). Furthermore, an observably higher rate of abnormal mitochondrial distribution (P < 0.05) and significantly decreased mitochondrial membrane potential (MMP) (P < 0.05) were observed in FB₁-exposed oocytes. In addition, ROS generation in FB₁-treated oocytes was rapidly increased (P < 0.05), while the transcriptional levels of antioxidant-related genes (CAT, SOD2 and GSH-Px) were sharply decreased compared with those in the control group. Additionally, the incidence of early apoptosis in FB₁-treated oocytes was also significantly increased (P < 0.05), suggesting that FB₁ exposure induced oxidative stress and further triggered apoptosis in porcine oocytes. Thus, these results suggested that FB₁ adversely affected oocyte maturation by disturbing cell cycle progression, destroying cytoskeletal dynamics and damaging mitochondrial function, which eventually induced oxidative stress and apoptosis in porcine oocytes.

Fumonisin B1 Epigenetically Regulates PTEN Expression and Modulates DNA Damage Checkpoint Regulation in HepG2 Liver Cells

Fumonisin B₁ (FB₁), a Fusarium-produced mycotoxin, is found in various foods and feeds. It is a well-known liver carcinogen in experimental animals; however, its role in genotoxicity is controversial. The current study investigated FB₁-triggered changes in the epigenetic regulation of PTEN and determined its effect on DNA damage checkpoint regulation in human liver hepatoma G2 (HepG2) cells. Following treatment with FB₁ (IC₅₀: 200 µM; 24 h), the expression of miR-30c, KDM5B, PTEN, H3K4me3, PI3K, AKT, p-ser473-AKT, CHK1, and p-ser280-CHK1 was measured using qPCR and/or Western blot. H3K4me3 enrichment at the PTEN promoter region was assayed via a ChIP assay and DNA damage was determined using an ELISA. FB₁ induced oxidative DNA damage. Total KDM5B expression was reduced, which subsequently increased the total H3K4me3 and the enrichment of H3K4me3 at PTEN promoters. Increased H3K4me3 induced an increase in PTEN transcript levels. However, miR-30c inhibited PTEN translation. Thus, PI3K/AKT signaling was activated, inhibiting CHK1 activity via phosphorylation of its serine 280 residue preventing the repair of damaged DNA. In conclusion, FB₁ epigenetically modulates the PTEN/PI3K/AKT signaling cascade, preventing DNA damage checkpoint regulation, and induces significant DNA damage.

Moscatilin, a bibenzyl derivative from the orchid Dendrobium loddigesii, induces apoptosis in melanoma cells

The use of orchids in herbal medicine has a very long history. Dendrobium species are known to produce a variety of secondary metabolites such as phenanthrens, bibenzyls, fluorenones and sesquiterpenes, and alkaloids and are responsible for their wide variety of medicinal properties. For decades, bibenzyls, which are the main bioactive components derived from Dendrobium species, have been subjected to extensive investigation as likely candidates for cancer treatment. The present study was undertaken to investigate the effect of moscatilin, a bibenzyl derivative from the orchid Dendrobium loddigesii on human melanoma cells. In A375 cells compound moscatilin showed a clear dose-response relationship in the range of 6.25-50 μM concentrations. In addition, we demonstrated an apoptotic response after treatment of cancer cells with this bibenzyl compound at 6.25 and 12.5 μM concentrations that probably involves PTEN activity, inhibition of Hsp70 expression and reactive oxygen species production. Alternatively, the inhibition of the caspase cascade at higher concentrations, 25 and 50 μM, correlated with additional reactive oxygen species increase, probably switched the mode of moscatilin-induced cell death from apoptosis to necrosis.

Isocordoin analogues promote apoptosis in human melanoma cells via Hsp70

Isocordin 1 and a series of 4-oxyalkyl-isocordoin analogues 2-8 were evaluated for their cytotoxicity effect against human melanoma cells (A2058). Analogues 4, 5, and 6 showed a higher inhibitory activity with IC₅₀ values of 12.91 ± 0.031, 24.88 ± 0.013, and 11.62 ± 0.017, respectively. These analogues, 4, 5, and 6, also induced an apoptotic response at 12.5- and 25-μM concentrations. They inhibited the expression of antiapoptotic proteins Bcl-2 and Hsp70, a critical factor that promotes tumour cell survival. In contrast, Bax and caspase-9 expression, and caspase-3 enzyme resulted activated. These results were correlated to a DNA fragmentation typical of apoptosis and an increase of intracellular reactive oxygen species (ROS) levels. Alternatively, at higher concentration (50 μM), when the capacity of the cells to sustain Hsp70 synthesis is reduced, our results seem to indicate that necrosis was induced by a further increase in ROS production. Therefore, the central finding in the present study is that these molecules downregulates Hsp70 expression. Altogether, these results suggest that 4-oxyalkyl-isocordoin analogues 4, 5, and 6 deserve to be deeply investigated for a possible application as Hsp70 inhibitor in the management of melanoma.

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.

Involvement of Bax and Bcl-2 in Induction of Apoptosis by Essential Oils of Three Lebanese Salvia Species in Human Prostate Cancer Cells

Prostate cancer is one of the most common forms of cancer in men, and research to find more effective and less toxic drugs has become necessary. In the frame of our ongoing program on traditionally used Salvia species from the Mediterranean Area, here we report the biological activities of Salvia aurea, S. judaica and S. viscosa essential oils against human prostate cancer cells (DU-145). The cell viability was measured by 3(4,5-dimethyl-thiazol-2-yl)2,5-diphenyl-tetrazolium bromide (MTT) test and lactate dehydrogenase (LDH) release was used to quantify necrosis cell death. Genomic DNA, caspase-3 activity, expression of cleaved caspase-9, B-cell lymphoma 2 (Bcl-2) and Bcl-2 associated X (Bax) proteins were analyzed in order to study the apoptotic process. The role of reactive oxygen species in cell death was also investigated. We found that the three essential oils, containing caryophyllene oxide as a main constituent, are capable of reducing the growth of human prostate cancer cells, activating an apoptotic process and increasing reactive oxygen species generation. These results suggest it could be profitable to further investigate the effects of these essential oils for their possible use as anticancer agents in prostate cancer, alone or in combination with chemotherapy agents.

Potential anticancer activity of lichen secondary metabolite physodic acid

Secondary metabolites present in lichens, which comprise aliphatic, cycloaliphatic, aromatic and terpenic compounds, are unique with respect to those of higher plants and show interesting biological and pharmacological activities. However, only a few of these compounds, have been assessed for their effectiveness against various in vitro cancer models. In the present study, we investigated the cytotoxicity of three lichen secondary metabolites (atranorin, gyrophoric acid and physodic acid) on A375 melanoma cancer cell line. The tested compounds arise from different lichen species collected in different areas of Continental and Antarctic Chile. The obtained results confirm the major efficiency of depsidones. In fact, depsides atranorin and gyrophoric acid, showed a lower activity inhibiting the melanoma cancer cells only at more high concentrations. Whereas the depsidone physodic acid, showed a dose-response relationship in the range of 6.25-50 μM concentrations in A375 cells, activating an apoptotic process, that probably involves the reduction of Hsp70 expression. Although the molecular mechanism, by which apoptosis is induced by physodic acid remains unclear, and of course further studies are needed, the results here reported confirm the promising biological properties of depsidone compounds, and may offer a further impulse to the development of analogues with more powerful efficiency against melanoma cells.

Individual and combined effects of feed artificially contaminated with with fumonisin B1 and T-2 toxin in weaned rabbits

Co-contamination of feed and feed raw materials with two or more mycotoxins is frequently reported, however, only a few studies have investigated the combined effects of low doses of multiple mycotoxins. In the present study the individual and combined effects of 10 mg/kg fumonisin B1 and 2 mg/kg T-2 toxin (n=12/group) were investigated in weaned rabbits. Mycotoxin contaminated feed was produced by adding fungal cultures of Fusarium verticillioides and Fusarium sporotrichioides, and fed to 40 days old rabbits during 28 days. Feed intake and body weight were measured weekly, serum biochemistry and antioxidant parameters on day 0, 14 and 28, while histopathological examination and comet assay were performed at the end of the experiment. T-2 exposure both alone and in combination resulted in 15-18% less final body weight compared to the control and FB1 treatment. There was a significant increase in the concentration of plasma total protein, albumin, fructosamine and creatinine in the group treated with FB1 compared to the control. The liver and the kidney of most animals treated with T-2 toxin, FB1 and their combination showed pathological changes, occurring more frequent in animals exposed to both toxins. T-2 resulted in depletion of lymphocytes in the spleen. FB1 and T-2 exerted synergistic effect on the antioxidant/oxidative parameters after 2 weeks of exposure, manifesting in less glutathione and glutathione peroxidase, while more malondialdehyde was produced. Both toxins caused DNA damage in the lymphocytes, which was more pronounced in the group fed T-2 toxin and T-2 combined with FB1, without additive or synergistic effects.

Fumonisin B₁ (FB₁) Induces Lamellar Separation and Alters Sphingolipid Metabolism of In Vitro Cultured Hoof Explants

One of the most important hoof diseases is laminitis. Yet, the pathology of laminitis is not fully understood. Different bacterial toxins, e.g. endotoxins or exotoxins, seem to play an important role. Additionally, ingestion of mycotoxins, toxic secondary metabolites of fungi, might contribute to the onset of laminitis. In this respect, fumonsins are of special interest since horses are regarded as species most susceptible to this group of mycotoxins. The aim of our study was to investigate the influence of fumonisin B₁ (FB₁) on primary isolated epidermal and dermal hoof cells, as well as on the lamellar tissue integrity and sphingolipid metabolism of hoof explants in vitro. There was no effect of FB₁ at any concentration on dermal or epidermal cells. However, FB₁ significantly reduced the separation force of explants after 24 h of incubation. The Sa/So ratio was significantly increased in supernatants of explants incubated with FB₁ (2.5–10 µg/mL) after 24 h. Observed effects on Sa/So ratio were linked to significantly increased sphinganine concentrations. Our study showed that FB₁ impairs the sphingolipid metabolism of explants and reduces lamellar integrity at non-cytotoxic concentrations. FB₁ might, therefore, affect hoof health. Further in vitro and in vivo studies are necessary to elucidate the effects of FB₁ on the equine hoof in more detail.

Panax ginseng extract modulates oxidative stress, DNA fragmentation and up-regulate gene expression in rats sub chronically treated with aflatoxin B1 and fumonisin B 1

Aflatoxins and fumonisins are important food-borne mycotoxins implicated in human health and have cytotoxic effects. The aims of the current study were to evaluate the protective role of Panax ginseng extract (PGE) against the synergistic effect of subchronic administration of aflatoxin B1 (AFB1) and fumonisin B1 (FB1) on DNA and gene expression in rat. Female Sprague-Dawley rats were divided into eight groups (ten rats/group) and treated for 12 weeks including the control group, the group having received AFB1 (80 µg/kg bw), the group having received FB1 (100 µg/kg bw), the group having received AFB1 plus FB1 and the groups having received PGE (20 mg/kg bw) alone or with AFB1 and/or FB1. At the end of experiment, liver and kidney were collected for the determination of DNA fragmentation, lipid peroxidation (LP), glutathione (GSH) contents and alterations in gene expression. The results indicated that these mycotoxins increased DNA fragmentation, LP and decreased GSH content in liver and kidney and down-regulated gene expression of antioxidants enzymes. The combined treatments with AFB1 and/or FB1 plus PGE suppressed DNA fragmentation only in the liver, normalized LP and increased GSH in the liver and kidney as well as up-regulated the expression of GPx, SOD1 and CAT mRNA. It could be concluded that AFB1 and FB1 have synergistic genotoxic effects. PGE induced protective effects against their oxidative stress and genotoxicity through its antioxidant properties.

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.

The cellular toxicology of mitragynine, the dominant alkaloid of the narcotic-like herb, Mitragyna speciosa Korth

The cytotoxicity of mitragynine, the dominant alkaloid of the narcotic-like herb, Mitragyna speciosa Korth (Kratom) involves cell cycle arrest, apoptosis and opiate receptors.

Toxic mechanisms induced by fumonisin b1 mycotoxin on human intestinal cell line

The gastrointestinal tract is the main target of exposure to mycotoxin fumonisin B1 (FB1), common natural contaminant in food. Previous studies reported that proliferating cells are more sensitive than confluent cells to the toxic effect of FB1. This study aims to investigate, by dose- and time-dependent experiments on human colon proliferating intestinal cell line (HT-29), the modifications induced by FB1 at concentrations ranging from 0.25 to 69 μM. The choice of highest FB1 concentration considered the low toxicity previously reported on intestinal cell lines, whereas the lowest one corresponded to the lower FBs levels permitted by European Commission Regulation. Different functional parameters were tested such as cell proliferation, oxidative status, immunomodulatory effect and changes in membrane microviscosity. In addition FB1-FITC localization in this cell line was assessed by using confocal laser scanning microscopy. Lipid peroxidation induction was the main and early (12 h) effect induced by FB1 at concentrations ranging from 0.5 to 69 μM, followed by inhibition of cell proliferation (up to 8.6 μM), the immunomodulatory effect (up to 17.2 μM), by assessing IL-8 secretion, and increase in membrane microviscosity (up to 34.5 μM). The toxic effects observed in different functional parameters were not dose-dependent and could be the consequence of the FB1 intracytoplasmatic localization as confirmed by confocal microscopy results. The different timescales and concentrations active of different functional parameters could suggest different cellular targets of FB1.

Stimulation of the proliferation of human normal esophageal epithelial cells by fumonisin B1 and its mechanism

Previous epidemiological studies have demonstrated a correlation between fumonisin B₁ (FB₁) and human esophageal cancer in China, Iran and South Africa. The purpose of this study was to investigate the effects of FB₁ on the proliferation, cell-cycle and apoptosis of normal human esophageal epithelial cells (HEECs) and to explore the molecular mechanisms of these effects. The proliferation of HEECs treated with FB₁ was assessed using a colorimetric assay, while analyses of the cell cycle and apoptosis were performed using flow cytometry and the measurement of the protein expressions of genes associated with the cell cycle was conducted using western blotting. The results showed that FB₁ stimulated the proliferation of HEECs, decreased the percentage of cells in the G0/G1 phase and reduced apoptosis. The western blotting results showed that FB₁ significantly increased the protein expression of cyclin D1 and significantly decreased the protein expression of cyclin E, p21 and p27. The results indicated that FB₁ stimulated the proliferation of HEECs by affecting the cell cycle and apoptosis. This mechanism was associated with changes in cyclin D1, cyclin E, p21 and p27 expression.

Application of mimotope peptides of fumonisin b1 in Peptide ELISA

Anti-fumonisin B(1) (FB(1)) McAb 1D11 was used as the target for biopanning from a phage random loop-constrained heptapeptide library. After three cycles of panning, seven phages with three mimotope peptides were selected to mimic the binding of FB(1) to 1D11. After the identification of phage ELISA, the phage clone that showed the best linear range of detection was chosen for further research. One peptide with the inserted peptide sequence of the phage was synthetized, named CT-452. An indirect competitive ELISA (peptide ELISA) for detecting FB(1) was established using the CT-452-bovine serum albumin conjugate as coating antigen. The linear range of the inhibition curve was 1.77-20.73 ng/mL. The half inhibitory concentration (IC50) was 6.06 ng/mL, and the limit of detection was 1.18 ng/mL. This method was compared with conventional indirect ELISA (commercial ELISA kit) and high-performance liquid chromatography (HPLC), and the results showed the reliability of the peptide ELISA for the determination of FB(1) in cereal samples. The relationship between the CT-452 and FB(1) standard concentrations in peptide ELISA was evaluated. The results indicated that synthetic peptide CT-452 can replace the FB(1) standard to establish an immunoassay free of FB(1).

Mechanisms of mycotoxin-induced neurotoxicity through oxidative stress-associated pathways

Among many mycotoxins, T-2 toxin, macrocyclic trichothecenes, fumonisin B(1) (FB(1)) and ochratochin A (OTA) are known to have the potential to induce neurotoxicity in rodent models. T-2 toxin induces neuronal cell apoptosis in the fetal and adult brain. Macrocyclic trichothecenes bring about neuronal cell apoptosis and inflammation in the olfactory epithelium and olfactory bulb. FB(1) induces neuronal degeneration in the cerebral cortex, concurrent with disruption of de novo ceramide synthesis. OTA causes acute depletion of striatal dopamine and its metabolites, accompanying evidence of neuronal cell apoptosis in the substantia nigra, striatum and hippocampus. This paper reviews the mechanisms of neurotoxicity induced by these mycotoxins especially from the viewpoint of oxidative stress-associated pathways.

Boldo prevents UV light and nitric oxide-mediated plasmid DNA damage and reduces the expression of Hsp70 protein in melanoma cancer cells

Objectives

This study was designed to investigate the potential protective effect of a methanolic extract of Peumus boldus leaves on UV light and nitric oxide (NO)-mediated DNA damage. In addition, we investigated the growth inhibitory activity of this natural product against human melanoma cells (M14).

Methods

Boldine, catechin, quercetin and rutin were identified using a HPLC method. The extract was incubated with plasmid DNA and, before irradiating the samples with UV-R, H2O2 was added. For analysis of DNA single-strand breaks induced by NO, the experiments were performed by incubating the extract with Angeli's salt. In the study on M14 cell line, cell viability was measured using MTT assay. Release of lactate dehydrogenase, a marker of membrane breakdown, was also measured. For the detection of apoptosis, the evaluation of DNA fragmentation (COMET assay) and caspase-3 activity assay were employed. The expression of heat shock protein 70 (Hsp70) was detected by Western blot analysis. Generation of reactive oxygen species was measured by using a fluorescent probe.

Key findings

The extract (demonstrating the synergistic effect of the constituents boldine and flavonoids), showed a protective effect on plasmid DNA and selectively inhibited the growth of melanoma cells. But a novel finding was that apoptosis evoked by this natural product in M14 cells, appears to be mediated, at least in part, via the inhibition of Hsp70 expression, which may be correlated with a modulation of redox-sensitive mechanisms.

Conclusions

These results confirm the promising biological properties of Peumus boldus and encourage in-vivo investigations into its potential anti-cancer activity.

Effects of aflatoxin B(1) and fumonisin B(1) on the viability and induction of apoptosis in rat primary hepatocytes

The present study evaluated the effect of aflatoxin B(1) (AFB(1)) and fumonisin B(1) (FB(1)) either alone, or in association, on rat primary hepatocyte cultures. Cell viability was assessed by flow cytometry after propidium iodine intercalation. DNA fragmentation and apoptosis were assessed by agarose gel electrophoresis and acridine orange and ethidium bromide staining. At the concentrations of AFB(1) and FB(1) used, the toxins did not decrease cell viability, but did induce apoptosis in a concentration and time-dependent manner.

Consumption of fumonisin B1 for 9 days induces stress proteins along the gastrointestinal tract of pigs

Fumonisin B(1) (FB1) is a mycotoxin which alters intestinal epithelial cell physiology and barrier properties, and accumulates in the colon. Data on effects of FB1 on stress proteins in the gastrointestinal tract (GIT) are lacking. Therefore, we hypothesized that repeated consumption of FB1 alters GIT tissue levels of stress proteins. This was tested using 36 weaned pigs fed a FB1 solution (n=18) or the vehicle (control; n=18) for 9 days. The pigs were then slaughtered, the organs were weighed and GIT tissues were collected for assessing GIT integrity, and for analysing stress proteins by Western blotting and densitometry (n=7 in each group). FB1 had little effects on growth rate but the liver was heavier (P<0.01) in FB1-fed pigs. alphaB crystallin and COX-1 concentrations were eight-fold and 12-fold higher in the colon of FB1-fed pigs than in the controls (P<0.0001). Concentrations of COX-1 and nNOS in the stomach, HSP 70 in the jejunum and HO-2 in the colon were also higher in FB1-fed pigs (P<0.05 to P<0.001). In conclusion, the FB1 extract drastically enhanced colonic levels of alphaB crystallin and COX-1, with milder increases in other stress proteins along the GIT of pigs. The data suggest that the colon is an important target for FB1-induced stress responses.

Oxidative Stress Induced by Fumonisin B1in Continuous Human and Rodent Neural Cell Cultures

Fumonisin B1 (FB1) is a mycotoxin produced by Fusarium verticillioides, which is a common infectant of corn and other cereal grains. Of concern to human health is also a possible airborne exposure to FB1-producing strains of F. verticillioides, which may grow in moisture-damaged buildings. In this study, we have characterized oxidative stress-related parameters induced by FB1 in three different neural cell lines, human SH-SY5Y neuroblastoma, rat C6 glioblastoma and mouse GT1-7 hypothalamic cells. The cells were exposed to graded doses of FB1 between 0.1 and 100 microM for 0-144 h after which the production of reactive oxygen species (ROS), lipid peroxidation, intracellular glutathione (GSH) levels and cell viability were measured. FB1 caused a dose-dependent increase of ROS production in C6 glioblastoma and GT1-7 hypothalamic cells but was without an effect in SH-SY5Y cells. Decreased GSH levels, increased MDA-formation, indicative of lipid peroxidation and necrotic cell death were observed in all cell lines after incubation with FB1. These findings indicate that FB1 induces oxidative stress in human, rat and mouse neural cell cultures.

A review of the toxic effects and mechanisms of action of fumonisin B1

Fumonisin B(1) (FB(1)) is a mycotoxin produced by the fungus Fusarium verticillioides, which commonly infects corn and other agricultural products. Fusarium species can also be found in moisture-damaged buildings, and, therefore, exposure of humans to Fusarium mycotoxins including FB(1) may take place. FB(1) bears a clear structural similarity to the cellular sphingolipids, and this similarity has been shown to disturb the metabolism of sphingolipids by inhibiting the enzyme ceramide synthase leading to accumulation of sphinganine in cells and tissues. FB(1) is neurotoxic, hepatotoxic, and nephrotoxic in animals, and it has been classified as a possible carcinogen to humans. The cellular mechanisms behind FB(1)-induced toxicity include the induction of oxidative stress, apoptosis, and cytotoxicity, as well as alterations in cytokine expression. The effects of FB(1) on different parameters vary markedly depending on what types of cells are studied or what species they originate from. These aspects are important to consider when evaluating the toxic potential of FB(1).

Early toxic effects of fumonisin B1 in rat liver

Mycotoxin fumonisin B1 (FB1) is hepatotoxic and carcinogenic in experimental animals. It is known that long-term exposure of experimental animals to FB1 causes apoptosis and lipid peroxidation. In this study, male adult Wistar rats were treated with single FB1 doses (5, 50, and 500 μg/kg b.w.) and sacrificed 4, 24, and 48 hours after treatment. Parameters of oxidative stress, histopathological changes, and DNA damage were monitored in the liver of treated and control animals. Parameters of oxidative stress were not affected by such treatment. A significant increase in apoptotic cells appeared in animals when 5 μg/kg b.w. dose was given and sacrificed after 24 hours with further increase at higher doses. In contrast to the number of mitotic figures and karyomegaly seen mostly at lower FB1 doses, necrosis was the prominent feature at higher doses. Significant increase in liver cells DNA mobility was observed 48 hours following treatment with 50 and 500 μg/kg b.w. as compared to control (tail length 15.2 ± 0.3, 16.4 ± 0.5, and 13.5 ± 0.1 μm, respectively). Tail intensity appeared to be more sensitive parameter for detecting DNA damage even at 5 μg/kg b.w. after 48 hours (1.69 ± 0.27% DNA; control 0.59 ± 0.11% DNA). This study proved that FB1-induced DNA damage is time- and dose-dependent, and that it could be caused in Wistar rats by a single dose.

Fumonisin B1 contamination of home-grown corn in high-risk areas for esophageal and liver cancer in China

Fumonisin B1 (FB1) is reportedly the causative agent of several animal mycotoxicoses and has etiologically been linked to human oesophageal and liver cancer in certain areas of South Africa and China. To study a possible relationship between exposure to FB1 and human cancer risk, the current status of FB1 contamination in food samples in Huaian and Fusui, where incidences of oesophageal and liver cancer are amongst the highest in China, was investigated. A total of 259 corn samples were collected from individual households in five villages of different townships in Huaian during December 2001 and December 2002, and in four villages of different townships in Fusui during May 2001 and May 2002. Corn samples were also collected from individual households in two villages in Huantai, an area with low incidences of both cancers. Enzyme-linked immunosorbent assays (ELISA) and immunoaffinity-HPLC methods were used for FB1 analysis. In corn samples from Huaian, FB1 was detectable in 95.7% (112/117) of the samples, with an average of 2.84 mg kg-1 (range 0.1-25.5 mg kg-1). FB1 was detected in 83.0% (78/94) of the Fusui samples, with an average of 1.27 mg kg-1 (range 0.1-14.9 mg kg-1), and in 83.3% (40/48) of Huantai samples, with an average of 0.65 mg kg-1 ranging from 0.1 to 5.7 mg kg-1. The level of FB1 in corn samples from Huaian was significantly higher than from Huantai (P < 0.001). In addition, 47 of 112 (42.0%) positive Huaian samples had FB1 level greater than 2.0 mg kg-1, which was significantly higher than 10.0% (4/40) of Huantai samples (P < 0.001). Furthermore, variations were found between samples collected in different years and different villages. The high contamination rates of FB1 found in food from these areas, along with previous reports, suggest a possible contributing role of FB1 in human esophageal- and hepato-carcinogenesis.