Cytotoxicity and genotoxicity of versicolorins and 5-methoxysterigmatocystin in A549 cells

The Biosynthesis, Structure Diversity and Bioactivity of Sterigmatocystins and Aflatoxins: A Review

Sterigmatocystins and aflatoxins are a group of mycotoxins mainly isolated from fungi of the genera Aspergillus. Since the discovery of sterigmatocystins in 1954 and aflatoxins in 1961, many scholars have conducted a series of studies on their structural identification, synthesis and biological activities. Studies have shown that sterigmatocystins and aflatoxins have a wide range of biological activities such as antitumour, antibacterial, anti-inflammatory, antiplasmodial, etc. The sterigmatocystins and aflatoxins had been shown to be hepatotoxic and nephrotoxic in animals. This review attempts to give a comprehensive summary of progress on the chemical structural features, synthesis, and bioactivity of sterigmatocystins and aflatoxins reported from 1954 to April 2024. A total of 72 sterigmatocystins and 20 aflatoxins are presented in this review. This paper reviews the chemical diversity and potential activity and toxicity of sterigmatocystins and aflatoxins, enhances the understanding of sterigmatocystins and aflatoxins that adversely affect humans and animals, and provides ideas for their prevention, research and development.

Assessment of the genotoxic and mutagenic effects induced by T-2 mycotoxin in HepG2 cells

The T-2 toxin is a mycotoxin produced by molds belonging to Fusarium. Among the Fusarium mycotoxins, trichothecenes are frequently reported in food and feed, being the T-2 toxin (T-2) the mycotoxin which possesses the highest toxicity. According to EFSA, T-2 is found in various cereal grains used in food and feed products, mainly in oats, and it has a high environmental impact due to its mechanisms of toxicity. However, recent information on its genotoxic and mutagenic effects is lacking. This work aimed to evaluate the genotoxic and mutagenic potential of T-2 in vitro. For this purpose, HepG2 cells were exposed to 15, 30, and 60 nM T-2 for 24 h, then the DNA damage was evaluated by the micronucleus and the comet assays. In addition, point mutation analysis was performed by the bacterial reverse mutation test using 0.15-60 nM of T-2 concentrations. The results showed chromosomal damage at 60 nM T-2 since significantly more MN appeared at this concentration than in the control samples. Regarding the comet assay, DNA double helix breaks appeared at all concentrations tested and, in a concentration-dependent manner. However, no mutagenic effects were observed at any of the concentrations tested for the Salmonella typhimurium (S. Typhimurium) strains TA98, TA100, TA1535, TA1537, or the Escherichia coli (E. Coli) WP2 strain in the absence or presence of a metabolic activation system. Therefore, these results showed that T-2 mycotoxin produced genotoxic effects by MN and comet assay, while no mutagenicity was observed. However, further research simulating different metabolic activation pathways and the combined exposure of this mycotoxin with other mutagenic chemicals that could be present in the diet is necessary to discard the mutagenic potential of T-2 fully. These results highlight the carcinogenic potential and danger associated with T-2 exposure and should be considered to prevent associated food risks for the human population.

Mutagenicity and genotoxicity assessment of the emerging mycotoxin Versicolorin A, an Aflatoxin B1 precursor

Aflatoxin B1 (AFB1) is the most potent natural carcinogen among mycotoxins. Versicolorin A (VerA) is a precursor of AFB1 biosynthesis and is structurally related to the latter. Although VerA has already been identified as a genotoxin, data on the toxicity of VerA are still scarce, especially at low concentrations. The SOS/umu and miniaturised version of the Ames test in Salmonella Typhimurium strains used in the present study shows that VerA induces point mutations. This effect, like AFB1, depends primarily on metabolic activation of VerA. VerA also induced chromosomal damage in metabolically competent intestinal cells (IPEC-1) detected by the micronucleus assay. Furthermore, results from the standard and enzyme-modified comet assay confirmed the VerA-mediated DNA damage, and we observed that DNA repair pathways were activated upon exposure to VerA, as indicated by the phosphorylation and/or relocation of relevant DNA-repair biomarkers (γH2AX and 53BP1/FANCD2, respectively). In conclusion, VerA induces DNA damage without affecting cell viability at concentrations as low as 0.03 μM, highlighting the danger associated with VerA exposure and calling for more research on the carcinogenicity of this emerging food contaminant.

Inhibitory Effects of Ehretia tinifolia Extract on the Excessive Oxidative and Inflammatory Responses in Lipopolysaccharide-Stimulated Mouse Kupffer Cells

Ehretia tinifolia (E. tinifolia) L., an evergreen tree with substantial biological activity, including antioxidant and anti-inflammatory effects, has been used in many herbal and traditional medicines. To elucidate its antioxidant and anti-inflammatory activity and the underlying mechanisms, we applied a methanol extract of E. tinifolia (ETME) to lipopolysaccharide (LPS)-stimulated mouse immortalized Kupffer cells. ETME suppressed the LPS-induced increase in nitric oxide, a mediator for oxidative stress and inflammation, and restored LPS-mediated depletion of total glutathione level by stabilizing antioxidative nuclear factor erythroid 2-related factor 2 (Nrf2) and the subsequent increase in heme oxygenase-1 levels. Furthermore, ETME inhibited the LPS-induced production of pro-inflammatory cytokines, including tumor necrosis factor-α, interleukin (IL)-1β, and IL-6. The inhibitory effects of ETME on pro-inflammatory responses were regulated by ETME-mediated dephosphorylation of mitogen-activated protein kinases (MAPKs: p38, p44/p42, and stress-associated protein kinase/c-Jun N-terminal kinase) and inhibition of nuclear localization of nuclear factor kappa B (NF-κB). These results suggest that ETME is a possible candidate for protecting Kupffer cells from LPS-mediated oxidative stress and excessive inflammatory responses by activating antioxidant Nrf2/HO-1 and inhibiting pro-inflammatory NF-κB and MAPKs, respectively.

Metabolism of versicolorin A, a genotoxic precursor of aflatoxin B1: Characterization of metabolites using in vitro production of standards

The toxicity of mycotoxins containing bisfuranoid structures such as aflatoxin B1 (AFB1) depends largely on biotransformation processes. While the genotoxicity and mutagenicity of several bisfuranoid mycotoxins including AFB1 and sterigmatocystin have been linked to in vivo bioactivation of these molecules into reactive epoxide forms, the metabolites of genotoxic and mutagenic AFB1 precursor versicolorin A (VerA) have not yet been characterized. Because this molecule is not available commercially, our strategy was to produce a library of metabolites derived from the biotransformation of in-house purified VerA, following incubation with human liver S9 fractions, in presence of appropriate cofactors. The resulting chromatographic and mass-spectrometric data were used to identify VerA metabolites produced by intestinal cell lines as well as intestinal and liver tissues exposed ex vivo. In this way, we obtained a panel of metabolites suggesting the involvement of phase I (M + O) and phase II (glucuronide and sulfate metabolites) enzymes, the latter of which is implicated in the detoxification process. This first qualitative description of the metabolization products of VerA suggests bioactivation of the molecule into an epoxide form and provides qualitative analytic data to further conduct a precise metabolism study of VerA required for the risk assessment of this emerging mycotoxin.

Cellular Cytotoxicity and Oxidative Potential of Recurrent Molds of the Genus Aspergillus Series Versicolores

Molds are ubiquitous biological pollutants in bioaerosols. Among these molds, the genus Aspergillus is found in the majority of indoor air samples, and includes several species with pathogenic and toxigenic properties. Aspergillus species in the series Versicolores remain little known despite recurrence in bioaerosols. In order to investigate their toxicity, we studied 22 isolates of clinical and environmental origin, corresponding to seven different species of the series Versicolores. Spore suspensions and ethyl acetate extracts prepared from fungal isolates were subjected to oxidative potential measurement using the dithiothreitol (DTT) test and cell survival measurement. The DTT tests showed that all species of the series Versicolores had an oxidative potential, either by their spores (especially for Aspergillus jensenii) or by the extracts (especially from Aspergillus amoenus). Measurements of cell survival of A549 and HaCaT cell lines showed that only the spore suspension containing 10⁵ spores/mL of Aspergillus jensenii caused a significant decrease in survival after 72 h of exposure. The same tests performed with mixtures of 10⁵ spores/mL showed a potentiation of the cytotoxic effect, with a significant decrease in cell survival for mixtures containing spores of two species (on A549 cells, p = 0.05 and HaCaT cells, p = 0.001) or three different species (on HaCaT cells, p = 0.05). Cell survival assays after 72 h of exposure to the fungal extracts showed that Aspergillus puulaauensis extract was the most cytotoxic (IC50 < 25 µg/mL), while Aspergillus fructus caused no significant decrease in cell survival.

Janus-Faced Molecules against Plant Pathogenic Fungi

The high cytotoxicity of the secondary metabolites of mycotoxins is capable of killing microbes and tumour cells alike, similarly to the genotoxic effect characteristic of Janus-faced molecules. The "double-edged sword" effect of several cytotoxins is known, and these agents have, therefore, been utilized only reluctantly against fungal infections. In this review, consideration was given to (a) toxins that could be used against plant and human pathogens, (b) animal models that measure the effect of antifungal agents, (c) known antifungal agents that have been described and efficiently prevent the growth of fungal cells, and (d) the chemical interactions that are characteristic of antifungal agents. The utilization of apoptotic effects against tumour growth by agents that, at the same time, induce mutations may raise ethical issues. Nevertheless, it deserves consideration despite the mutagenic impact of Janus-faced molecules for those patients who suffer from plant pathogenic fungal infections and are older than their fertility age, in the same way that the short-term cytotoxicity of cancer treatment is favoured over the long-term mutagenic effect.

Cytotoxicity, Antimicrobial, and In Silico Studies of Secondary Metabolites From Aspergillus sp. Isolated From Tecoma stans (L.) Juss. Ex Kunth Leaves

Endophytes are prolific producers of privileged secondary metabolites with diverse therapeutic potential, although their anticancer and antimicrobial potential still have a room for further investigation. Herein, seven known secondary metabolites namely, arugosin C (1), ergosterol (2), iso-emericellin (3), sterigmatocystin (4), dihydrosterigmatocystin (5), versicolorin B (6), and diorcinol (7) were isolated from the rice culture of Aspergillus sp. retrieved from Tecoma stans (L.) Juss. ex Kunth leaves. Their anticancer and antimicrobial activities were evaluated in MTT and agar well diffusion assays, respectively. The cytotoxicity results showed that metabolite 3 displayed the best viability inhibition on the MCF-7 breast cancer cells with IC₅₀ = 225.21 µM, while 5 on the HepG2 hepatocellular carcinoma cells with IC₅₀ = 161.81 µM. 5 demonstrated a 60% apoptotic mode of cell death which is virtually correlated to its high docking affinity to Hsp90 ATP binding cleft (binding score −8.4 Kcal/mol). On the other side, metabolites 4 and 5 displayed promising antimicrobial activity especially on Pseudomonas aeruginosa with MIC = 125 μg/ml. The observed effect may be likely related to their excellent in silico inhibition of the bacterial DNA-gyrase kinase domain (binding score −10.28 Kcal/mol). To the best of our knowledge, this study is the first to report the promising cytotoxic and antibacterial activities of metabolites 3, 4, and 5 which needs further investigation and renovation to therapeutic leads.

Sterigmatocystin, 5-Methoxysterigmatocistin, and Their Combinations Are Cytotoxic and Genotoxic to A549 and Hepg2 Cells and Provoke Phosphorylation of Chk2, but Not Fancd2 Checkpoint Proteins

Sterigmatocystin (STC) and 5-methoxysterigmatocystin (5-M-STC) are structurally related mycotoxins with cytotoxic and genotoxic properties. In the present study, we hypothesized that DNA damage induced by non-cytotoxic concentrations of single and combined mycotoxins could alter the phosphorylation of the checkpoint proteins Chk2 and FANCD2 (ELISA) in HepG2 and A549 cells. The cytotoxic potential (MTT test) of single and combined STC and 5-M-STC, the nature of their interaction (additivity, antagonism, or synergy) and DNA damage level (alkaline comet assay) in HepG2 and A549 cells were also investigated. All experiments were performed after 24 h of mycotoxin treatment. 5-M-STC was 10-folds more cytotoxic than STC to both HepG2 and A549 cells. Both mycotoxins are genotoxic to HepG2 and A549 cells by inducing both double and single DNA strand breaks that activate Chk2 (especially in HepG2 cells) but not the FANCD2 protein. STC exerted higher genotoxic potential than 5-M-STC in HepG2 and A549 cells when both toxins were applied individually at the same concentration. Dual combinations of non-cytotoxic mycotoxin concentrations showed additive to antagonizing cytotoxic and genotoxic effects. The absence and low activation of checkpoint proteins during prolonged exposure to non-cytotoxic concentrations of STC and 5-M-STC could support cell proliferation and carcinogenesis.

Versicolorin A enhances the genotoxicity of aflatoxin B1 in human liver cells by inducing the transactivation of the Ah-receptor

Aflatoxins are a group of mycotoxins that have major adverse effects on human health. Aflatoxin B1 (AFB1) is the most important aflatoxin and a potent carcinogen once converted into a DNA-reactive form by cytochrome P450 enzymes (CYP450). AFB1 biosynthesis involves the formation of Versicolorin A (VerA) which shares structural similarities with AFB1 and can be found in contaminated commodities, often co-occurring with AFB1. This study investigated and compared the toxicity of VerA and AFB1, alone or in combination, in HepG2 human liver cells. Our results show that both toxins have similar cytotoxic effects and are genotoxic although, unlike AFB1, the main genotoxic mechanism of VerA does not involve the formation of DNA double-strand breaks. Additionally, we show that VerA activates the aryl hydrocarbon receptor (AhR) and significantly induce the expression of the CYP450-1A1 (CYP1A1) while AFB1 did not induce AhR-dependent CYP1A1 activation. Combination of VerA with AFB1 resulted in enhanced genotoxic effects, suggesting that AhR-activation by VerA influences AFB1 genotoxicity by promoting its bioactivation by CYP450s to a highly DNA-reactive metabolite. Our results emphasize the need for expanding the toxicological knowledge regarding mycotoxin biosynthetic precursors to identify those who may pose, directly or indirectly, a threat to human health.

Fungi and their secondary metabolites in water-damaged indoors after a major flood event in eastern Croatia

In winter and summer of 2016 and 2017, airborne fungi and house dust were collected in indoors of the village Gunja, which had been flooded, and the control village Gornji Stupnik (Croatia) in order to explore variations of fungal indoor levels, particularly Aspergilli section Nidulantes series Versicolores, as well as fungal metabolites in dust. Levels of airborne Aspergilli (Versicolores) were three times as high in winter and summer in Gunja than in the control village, while dustborne isolates were equally present in both locations. Sequencing of the calmodulin gene region revealed that among Aspergilli (Versicolores), A. jensenii and A. creber were dominant and together with A. puulaauensis, A. tennesseensis and A. venenatus produced sterigmatocystin and 5-methoxysterigmatocystin (HPLC coupled with mass spectrometry); A. amoenus, A. fructus, A. griseoaurantiacus, A. pepii, and A. protuberus produced sterigmatocystin but not 5-methoxysterigmatocystin; A. sydowii did not produce any of these toxins. A total of 75 metabolites related to Penicillium (29), Aspergillus (22), Fusarium (10), Alternaria (5), Stachybotrys (2), and other fungi (7) were detected in dust by liquid chromatography-tandem mass spectrometry. The majority of metabolites including sterigmatocystin and 5-methoxysterigmatocystin exhibited a higher prevalence in winter in Gunja.

Single-Dose Toxicity of Individual and Combined Sterigmatocystin and 5-Methoxysterigmatocistin in Rat Lungs

Sterigmatocystin (STC) and 5-methoxysterigmatocystin (5-M-STC) are mycotoxins produced by common damp indoor Aspergilli series Versicolores. Since both STC and 5-M-STC were found in the dust of indoor occupational and living areas, their occupants may be exposed to these mycotoxins, primarily by inhalation. Thus, STC and 5-M-STC were intratracheally instilled in male Wistar rats using doses (0.3 mg STC/kg of lung weight (l.w.); 3.6 mg 5-M-STC/kg l.w.; toxin combination 0.3 + 3.6 mg/kg l.w.) that corresponded to concentrations detected in the dust of damp indoor areas in order to explore cytotoxicity, vascular permeability, immunomodulation and genotoxicity. Single mycotoxins and their combinations insignificantly altered lactate-dehydrogenase activity, albumin, interleukin-6, tumor necrosis factor-α and chemokine macrophage inflammatory protein-1α concentrations, as measured by ELISA in bronchioalveolar lavage fluid upon 24 h of treatment. In an alkaline comet assay, both mycotoxins provoked a similar intensity of DNA damage in rat lungs, while in a neutral comet assay, only 5-M-STC evoked significant DNA damage. Hence, naturally occurring concentrations of individual STC may induce DNA damage in rat lungs, in which single DNA strand breaks prevail, while 5-M-STC was more responsible for double-strand breaks. In both versions of the comet assay treatment with STC + 5-M-STC, less DNA damage intensity occurred compared to single mycotoxin treatment, suggesting an antagonistic genotoxic action.

Near-infrared reflectance spectroscopy-based fast versicolorin A detection in maize for early aflatoxin warning and safety sorting

Aflatoxins (AFs) are potent carcinogens present in numerous crops. Access to accurate methods for evaluating contamination is a critical factor in aflatoxin risk assessment. Versicolorin A (Ver A), a precursor of aflatoxin B₁ (AFB₁), can be used as an indicator for the presence of AFB₁, even when the AF is not yet detectable. Currently employed Ver A detection methods are expensive, time consuming, and difficult to apply to numerous samples. Herein, Ver A was detected via near-infrared spectroscopy. Both quantitative and two-grade sorting methods were set-up using the extreme gradient boosting algorithm coupled with a support vector machine. This two-tiered method obtained a root-mean-square error of prediction value of 3.57 μg/kg for the quantitative model, and an accuracy rate of 90.32% for the sorting approach. This novel method is rapid, accurate, solvent free, requires no sample pretreatment, and detects Ver A in maize, making it convenient for practical use.

Versicolorin A, a precursor in aflatoxins biosynthesis, is a food contaminant toxic for human intestinal cells

Aflatoxin B₁ (AFB₁) is the most potent carcinogen among mycotoxins. Its biosynthesis involves the formation of versicolorin A (VerA), whose chemical structure shares many features with AFB₁. Our data revealed significant levels of VerA in foodstuff from Central Asia and Africa. Given this emerging food risk, it was of prime interest to compare the toxic effects of the two mycotoxins against cells originating from the intestinal tract. We used human colon cell lines (Caco-2, HCT116) to investigate the cytotoxic process induced by the two mycotoxins. Contrary to AFB₁, a low dose of VerA (1 µM) disturbed the expression level of thousands of genes (18 002 genes). We show that the cytotoxic effects of low doses of VerA (1-20 µM) were stronger than the same low doses of AFB₁ in both Caco-2 and HCT116 cell lines. In Caco-2 cells, VerA induced DNA strand breaks that led to apoptosis and reduced DNA replication of dividing cells, consequently inhibiting cell proliferation. Although VerA was able to induce the p53 signaling pathway in p53 wild-type HCT116 cells, its toxicity process did not mainly rely on p53 expression since similar cytotoxic effects were also observed in HCT116 cells that do not express p53. In conclusion, this study provides evidence of the risk of food contamination by VerA and shed light on its toxicological effect on human colon cells.

New Diketopiperazines from a Marine-Derived Fungus Strain Aspergillus versicolor MF180151

Six new diketopiperazines, (±)-7,8-epoxy-brevianamide Q ((±)-1), (±)-8-hydroxy-brevianamide R ((±)-2), and (±)-8-epihydroxy-brevianamide R ((±)-3), together with four known compounds, (±)-brevianamide R ((±)-4), versicolorin B (5) and averufin (6), were isolated from a marine-derived fungus strain Aspergillus versicolor MF180151, which was recovered from a sediment sample collected from the Bohai Sea, China. The chemical structures were established by 1D- and 2D-NMR spectra and HR-ESI-MS. 1 is the first sample of brevianamides with an epoxy moiety. Their bioactivities were evaluated against Candida albicans, Bacillus subtilis, Staphylococcus aureus, methicillin-resistant S. aureus, Pseudomonas aeruginosa, and Bacillus Calmette-Guérin. Compounds 1–4 showed no activities against the pathogens, and compounds 5 and 6 showed moderate activities against S. aureus and methicillin-resistant S. aureus.

Aflatoxin production and in vitro toxicity of Aspergilli section Flavi isolated from air samples collected from different environments

Aspergilli section Flavi, originally isolated from air samples collected from inhabited apartments (AP), unoccupied basements (BS), and processing facilities of a grain mill (GM), were analyzed for their potential to produce aflatoxin B₁ (AFB₁) on solid media. The isolates were further characterized with regard to their cytotoxic, genotoxic, and pro-inflammatory properties in vitro. Aspergilli were identified based on partial calmodulin (CaM) gene sequencing; the producing capacities of isolates were analyzed by HPLC/FLD and confirmed by genes in biosynthesis (aflR, norA, omtA). In the grain mill, the Aspergilli section Flavi (up to 1.3 × 10⁶ cfu/m³) dominated by AFB₁-producing Aspergillus flavus (71%, 4.5-5254 ng/ml) which showed a serious health risk for workers. Living environments were not relevant sources of exposure. After 24 h, AFB₁ (1-100 μmol/l) reduced cell viability (MTT test) in both A549 cells and THP-1 macrophage-like cells without reaching IC₅₀. In A549 cells, the extract of the AFB₁-producing A. flavus significantly decreased cell viability but not below 50%. THP-1 macrophage-like cells were more sensitive to both extracts, but IC₅₀ was obtained only for the AFB₁-producing strain (0.37 mg/ml; AFB₁ 2.78 μmol/l). AFB₁ (1 and 10 μmol/l) induced significant DNA damage (tail intensity, alkaline comet assay) in A549 cells in contrast to Aspergilli extracts. AFB₁ elevated IL-6 and IL-8, while Aspergilli extracts increased IL-1β, TNF-α, and IL-17 release in THP-1 macrophages (ELISA). Chronic exposure to AFB₁ and/or other metabolites in airborne A. flavus from occupational environments may stimulate epithelial damage of airways accompanied by lowered macrophage viability.

Aflatoxin B1 and M1: Biological Properties and Their Involvement in Cancer Development

Aflatoxins are fungal metabolites found in feeds and foods. When the ruminants eat feedstuffs containing Aflatoxin B1 (AFB1), this toxin is metabolized and Aflatoxin M1 (AFM1) is excreted in milk. International Agency for Research on Cancer (IARC) classified AFB1 and AFM1 as human carcinogens belonging to Group 1 and Group 2B, respectively, with the formation of DNA adducts. In the last years, some epidemiological studies were conducted on cancer patients aimed to evaluate the effects of AFB1 and AFM1 exposure on cancer cells in order to verify the correlation between toxin exposure and cancer cell proliferation and invasion. In this review, we summarize the activation pathways of AFB1 and AFM1 and the data already reported in literature about their correlation with cancer development and progression. Moreover, considering that few data are still reported about what genes/proteins/miRNAs can be used as damage markers due to AFB1 and AFM1 exposure, we performed a bioinformatic analysis based on interaction network and miRNA predictions to identify a panel of genes/proteins/miRNAs that can be used as targets in further studies for evaluating the effects of the damages induced by AFB1 and AFM1 and their capacity to induce cancer initiation.

Versicolorin A is a potential indicator of aflatoxin contamination in the granary-stored corn

The objective of this study was to evaluate the feasibility of the predictive monitoring of aflatoxin B₁ (AFB₁) under granary conditions, since mycotoxin contamination of the stored grain represents an important issue. Using the storage test, we investigated the relationship between versicolorin A (Ver A, an intermediate in AFB₁ biosynthesis) levels and the levels of aflatoxigenic fungi, and their relationship with aflatoxin production. All samples, except for one, were found to be contaminated with aflatoxigenic fungi using PCR analyses, while their AFB₁ levels were not detectable before the storage test using an enzyme-linked immunosorbent assay (ELISA) method with an LOD of 2 μg/kg. Aflatoxigenic fungi levels were analysed, as well as Ver A levels prior to the accumulation of AFB₁ (Levels were ≥5 μg/kg; the permissible levels of AFB₁ in corn intended for direct consumption are <5 μg/kg (EC)). Statistical analyses demonstrated that aflatoxin levels after both actual storage and safe storage (AFB₁˂5μg/kg) times are significantly correlated with the Ver A levels and the changes in Ver A levels (ΔVer A). Both high and variable Ver A levels were indicative of the vigorous metabolic activity of aflatoxigenic fungi. In contrast, steady Ver A levels showed that aflatoxin production by the fungi was not active. Monitoring Ver A levels and their changes may allow an earlier detection of harmful aflatoxin contamination in the stored grain. Additionally, the toxicity of Ver A should be further examined. The results of our study indicate that the monitoring of Ver A levels, even when the AFB₁ levels are very low, may increase the safety of grain consumption, especially considering Ver A toxicity.

Anti-neuroinflammatory effect of 6,8,1'-tri-O-methylaverantin, a metabolite from a marine-derived fungal strain Aspergillus sp., via upregulation of heme oxygenase-1 in lipopolysaccharide-activated microglia

In the course of searching for anti-neuroinflammatory metabolites from marine-derived fungi, three fungal metabolites, 6,8,1'-tri-O-methylaverantin, 6,8-di-O-methylaverufin, and 5-methoxysterigmatocystin were isolated from a marine-derived fungal strain Aspergillus sp. SF-6796. Among these, 6,8,1'-tri-O-methylaverantin induced the expression of heme oxygenase (HO)-1 protein in BV2 microglial cells. The induction of HO-1 protein was mediated by the activation of nuclear transcription factor erythroid-2 related factor 2 (Nrf2), and was regulated by the p38 mitogen-activated protein kinase and phosphatidylinositol 3-kinase/protein kinase B signaling pathways. Furthermore, 6,8,1'-tri-O-methylaverantin suppressed the overproduction of pro-inflammatory mediators, such as nitric oxide, prostaglandin E₂, inducible nitric oxide synthase, and cyclooxygenase-2 in lipopolysaccharide (LPS)-stimulated BV2 microglial cells. These anti-neuroinflammatory effects were mediated through the negative regulation of the nuclear factor kappa B pathway, repressing the phosphorylation and degradation of inhibitor kappa B-α, translocation into the nucleus of p65/p50 heterodimer, and DNA-binding activity of p65 subunit. The anti-neuroinflammatory effect of 6,8,1'-tri-O-methylaverantin was partially blocked by a selective HO-1 inhibitor, suggesting that its anti-neuroinflammatory effect is at least partly mediated by HO-1 induction. In this study, 6,8,1'-tri-O-methylaverantin also induced HO-1 protein expression in primary microglial cells, and this correlated with anti-neuroinflammatory effects observed in LPS-stimulated primary microglial cells. In conclusion, 6,8,1'-tri-O-methylaverantin represents a potential candidate for use in the development of therapeutic agents for the regulation of neuroinflammation in neurodegenerative diseases.

Aspergillus korhogoensis, a Novel Aflatoxin Producing Species from the Côte d'Ivoire

Several strains of a new aflatoxigenic species of Aspergillus, A. korhogoensis, were isolated in the course of a screening study involving species from section Flavi found contaminating peanuts (Arachis hypogaea) and peanut paste in the Côte d'Ivoire. Based on examination of four isolates, this new species is described using a polyphasic approach. A concatenated alignment comprised of nine genes (ITS, benA, cmdA, mcm7, amdS, rpb1, preB, ppgA, and preA) was subjected to phylogenetic analysis, and resulted in all four strains being inferred as a distinct clade. Characterization of mating type for each strain revealed A. korhogoensis as a heterothallic species, since three isolates exhibited a singular MAT1-1 locus and one isolate exhibited a singular MAT1-2 locus. Morphological and physiological characterizations were also performed based on their growth on various types of media. Their respective extrolite profiles were characterized using LC/HRMS, and showed that this new species is capable of producing B- and G-aflatoxins, aspergillic acid, cyclopiazonic acid, aflavarins, and asparasones, as well as other metabolites. Altogether, our results confirm the monophyly of A. korhogoensis, and strengthen its position in the A. flavus clade, as the sister taxon of A. parvisclerotigenus.

Species diversity and cytotoxic potency of airborne sterigmatocystin-producing Aspergilli from the section Versicolores

This study presents the distribution and species diversity of sterigmatocystin-producing Aspergilli from the section Versicolores in the indoor air of apartment-AP, basements-BS and grain mill-GM in Croatia, as well as the cytotoxic potency of isolates. The species comprised 0.7-20% of total airborne fungi detected in the AP, 11-55% in the BS, and 0-2% in the GM. Based on CaM sequences, seven species were identified; dominant were Aspergillus jensenii and Aspergillus creber, followed by Aspergillus protuberus, Aspergillus venenatus, Aspergillus tennesseensis, Aspergillus amoenus, Aspergillus griseoaurantiacus and three undescribed species. All of the identified species produced sterigmatocystin-STC (HPLC/UV-VIS); A. griseoaurantiacus (208.29μg/mL) and A. jensenii (1.192-133.63μg/mL) produced the highest levels, the lowest were detected in A. protuberus and A. tennesseensis (0.117-2.749μg/mL). Lower species diversity was obtained in the GM due to overgrowth with more propulsive fungi. Relatively high STC levels (0.06-2.35μg/g) detected in 52% of GM dust samples confirmed the presence of STC-producers, although this STC cannot be exclusively attributed to Aspergilli (Versicolores). STC and the majority of STC-producing Aspergilli were cytotoxic to human lung A549 cells (IC50 0.9-2.3μg/mL) and THP-1 macrophage-like cells (IC50 0.3-0.6μg/mL) in relatively low concentrations suggesting that humans can be at high risk during chronic exposure.

Anthraquinones and Derivatives from Marine-Derived Fungi: Structural Diversity and Selected Biological Activities

Anthraquinones and their derivatives constitute a large group of quinoid compounds with about 700 molecules described. They are widespread in fungi and their chemical diversity and biological activities recently attracted attention of industries in such fields as pharmaceuticals, clothes dyeing, and food colorants. Their positive and/or negative effect(s) due to the 9,10-anthracenedione structure and its substituents are still not clearly understood and their potential roles or effects on human health are today strongly discussed among scientists. As marine microorganisms recently appeared as producers of an astonishing variety of structurally unique secondary metabolites, they may represent a promising resource for identifying new candidates for therapeutic drugs or daily additives. Within this review, we investigate the present knowledge about the anthraquinones and derivatives listed to date from marine-derived filamentous fungi's productions. This overview highlights the molecules which have been identified in microorganisms for the first time. The structures and colors of the anthraquinoid compounds come along with the known roles of some molecules in the life of the organisms. Some specific biological activities are also described. This may help to open doors towards innovative natural substances.

Mycotoxins and other fungal metabolites in grain dust from Norwegian grain elevators and compound feed mills

Employees at grain elevators and compound feed mills are exposed to large amounts of grain dust during work, frequently leading to airway symptoms and asthma. Although the exposure to grain dust, microorganisms, β-1→3-glucans and endotoxins has been extensively studied, the focus on the mycotoxin content of grain dust has previously been limited to one or few mycotoxins. Our objective was therefore to screen settled grain dust from grain elevators and compound feed mills for fungal metabolites by LC/MS-MS and explore differences between work places, seasons and climatic zones. Seventy fungal metabolites and two bacterial metabolites were detected. Trichothecenes, depsipeptides, ergot alkaloids, and other metabolites from Fusarium, Claviceps, Alternaria, Penicillium, Aspergillus, and other fungi were represented. The prevalence of individual metabolites was highly variable, and the concentration of each metabolite varied considerably between samples. The prevalence and concentration of most metabolites were higher in grain elevators compared to compound feed mills. Differences between seasons and climatic zones were inconclusive. All samples contained multiple mycotoxins, indicating a highly complex pattern of possible inhalational exposure. A mean exposure of 20 ng/m3 of fungal metabolites was estimated, whereas a worst case scenario estimated as much as 10 ?g/m3. Although many of these compounds may be linked to toxicological and immunological effects through experimental or epidemiological studies, it still remains to be determined whether the detected concentrations implicate adverse health outcomes when inhaled.

Proapoptotic activity of aflatoxin B1 and sterigmatocystin in HepG2 cells

Aflatoxin B1 (AFB1) and sterigmatocystin (ST) are two hepatocarcinogenic mycotoxins that are commonly coexisted in cereal grains, and their co-proapoptotic activity in HepG2 cells was studied. The values of IC50, which is the dosage of mycotoxin resulting in a 50% cell growth inhibition measured by a sulforhodamine B (SRB) colorimetric assay, were 16.9 μM and 7.3 μM for AFB1 and ST, respectively. Additively and dose-dependently, cell apoptosis-related toxicity endpoints of double strand DNA and ATP content were decreased while the intracellular ROS and mitochondria membrane permeability (MMP) were increased. Consistently, when cell cycle is arrest at G0/G1 or S phase by AFB1 and/or ST, the experimental results from flow cytometry assay demonstrated that the rate of cell apoptosis and mitochondrial membrane potential were also additively increased and decreased, respectively, in a dose-dependent manner. Thus, the integrity of mitochondria (MMP and membrane potential) that is the central component of cell apoptosis is disrupted by AFB1 and ST in an additive manner. With the immunocytochemistry analysis showing increased expression of apoptosis-related proteins of Bax, Caspase-3 and p53 and decreased expression of Bcl-2 protein, an additive nature of the co-proapoptotic activity of AFB1 and ST was revealed.

Mycotoxins' activity at toxic and sub-toxic concentrations: differential cytotoxic and genotoxic effects of single and combined administration of sterigmatocystin, ochratoxin A and citrinin on the hepatocellular cancer cell line Hep3B

Food safety organizations indicate the likelihood of constant human and animal exposure to mycotoxin mixtures as a possible negative public health impact. Risk assessment demonstrates that certain mycotoxins of Aspergillus and Penicillium spp. are toxic and hold a significant genotoxic efficacy at nanomolar concentrations. The aim of the current study was to investigate the potential cytogenetic effects of sterigmatocystin (STER), ochratoxin A (OTA) and citrinin (CTN) alone or in combination, at pM to μΜ concentrations, on the human hepatocellular cancer cell line Hep3B. MTT reduction, mitotic divisions, cell cycle delays and sister chromatid exchange rates (SCE) were determined as endpoints of metabolic activity, cytotoxicity, cytostaticity, and genotoxicity, respectively. All mycotoxin treatments induce SCE rates from 10-12 M, while their cytotoxic and cytostatic potential varies. In PRI and MI assays, but not at MTT, STER alone or in combination with OTA + CTN appeared cytostatic and cytotoxic, even at 10-12 M, while CTN alone and all other combinations displayed substantial cellular survival inhibition in doses ≥ 10-8 M. Co-administration of STER + OTA or STER + CTN in concentrations ≤ 10-1 M, increased the MI and MTT activity, while it did not affect the PRI. Mycotoxin co-treatments revealed in general similar-to-additive or antagonistic genotoxic and cytotoxic effects. Our results for the first time describe that STER alone or in combination with OTA and/or CTN share a cytotoxic and cytogenetic potential even at picoMolar concentrations on human hepatoma cells in vitro.

Faces of a changing climate: semi-quantitative multi-mycotoxin analysis of grain grown in exceptional climatic conditions in Norway

Recent climatological research predicts a significantly wetter climate in Southern Norway as a result of global warming. Thus, the country has already experienced unusually wet summer seasons in the last three years (2010–2012). The aim of this pilot study was to apply an existing multi-analyte LC-MS/MS method for the semi-quantitative determination of 320 fungal and bacterial metabolites in Norwegian cereal grain samples from the 2011 growing season. Such knowledge could provide important information for future survey and research programmes in Norway. The method includes all regulated and well-known mycotoxins such as aflatoxins, trichothecenes, ochratoxin A, fumonisins and zearalenone. In addition, a wide range of less studied compounds are included in the method, e.g., Alternaria toxins, ergot alkaloids and other metabolites produced by fungal species within Fusarium, Penicillium and Aspergillus. Altogether, 46 metabolites, all of fungal origin, were detected in the 76 barley, oats and wheat samples. The analyses confirmed the high prevalence and relatively high concentrations of type-A and -B trichothecenes (e.g., deoxynivalenol up to 7230 µg/kg, HT-2 toxin up to 333 µg/kg). Zearalenone was also among the major mycotoxins detected (maximum concentration 1670 µg/kg). Notably, several other Fusarium metabolites such as culmorin, 2-amino-14,16-dimethyloctadecan-3-ol and avenacein Y were co-occurring. Furthermore, the most prevalent Alternaria toxin was alternariol with a maximum concentration of 449 µg/kg. A number of Penicillium and Aspergillus metabolites were also detected in the samples, e.g., sterigmatocystin in concentrations up to 20 µg/kg.

Fungal profiles in various milk thistle botanicals from US retail

Milk thistle (MT) dietary supplements are widely consumed due to their possible beneficial effect on liver health. As botanicals, they can be contaminated with a variety of fungi and their secondary metabolites, mycotoxins. This study was conducted in an effort to determine the mycological quality of various MT botanical supplements from the US market. Conventional plating methods were used for the isolation and enumeration of fungi, while conventional microscopy as well as molecular methods were employed for the speciation of the isolated strains. Results showed that a high percentage of the MT samples tested were contaminated with fungi. Total counts ranged between <2.00 and 5.60 log10 colony forming units per gram (cfu/g). MT whole seeds carried the highest fungal levels followed by MT cut herb. No live fungi were recovered from MT seed tea bags, liquid extracts, capsules or soft gels. Potentially toxigenic molds from the Aspergillus sections Flavi and Nigri as well as Eurotium, Penicillium, Fusarium and Alternaria species were isolated from MT supplements. The predominant molds were Eurotia (E. repens, E. amstelodami and E. rubrum), A. flavus, A. tubingensis, A. niger and A. candidus. To our knowledge, this is the first study reporting on fungal contamination profiles of MT botanicals.