International audience | 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.

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.

Mycotoxins are high toxic, widely distributed contaminants in foodstuff. In this study, a aflatoxin B1 (AFB1) degrading strain S. acidoaminiphila CW117 was screened, and its detoxification characteristics were investigated. Substrate AFB1 at 45 μg/L was degraded by CW117 within 24 h; meanwhile, 4.1 mg/L AFB1 was almost degraded within 48 h. After 24 h degradation, the biotoxicity of the detoxified culture was eliminated. Strain CW117 efficient degradation to AFB1 (especially to low AFB1 concentrations) suggested its potential significance to detoxification development on food and feedstuff. The active degradation components present in the cell-free supernatant. The degradation ratio increased constantly with increasing incubation temperature raised (0–90 °C) and was even stable at 90 °C. Degradation was optimal at pH 6–7, and was only partially inhibited by metal-chelators (EDTA and EGTA), proteinase K, and a protein denaturant (sodium dodecyl sulfate, SDS). The recombinant laccase rLC1 (0.5 mg/mL) from CW117 degraded 29.3% of AFB1 within 24 h; however, the cell-free supernatant degraded 76.7% of the toxin in same time, with much lower protein content. The results indicated the CW117 degrades AFB1 via a combination of enzymes and micro-molecule oxides.

This study focused on the possible chemo-preventive effects of insect peptide CopA3 on normal human colon cells against the inflammation induced by the toxic environmental pollutant aflatoxin B1 (AFB1). In the study, we used CCD 841 CoN normal human colon cells to investigate the cytotoxic effect induced by AFB1 and elucidated the negative impact of AFB1 exposure on the cell cycle progression. Further, we also carried out the in-vivo experiment, where male BALB/c mice were administrated with AFB1 to induce inflammation associated cancer like phenotype and the dietary effect of CopA3 was evaluated on the early stages of AFB1-induced hepatotoxicity and inflammation in colon tissues. At the initiation stage, CopA3 was given along with water, which significantly decreased the inflammation in the liver and colon of AFB1 exposed mice model. Mice that received CopA3 alone showed enhanced activity of several antioxidant enzymes. In the post treatment stage, the CopA3 dosage remarkably increased the Ki-67 protein expression, indicating the enhancement in cell proliferation event and increased the number of apoptotic cells in colonic crypts, suggesting the capability of CopA3 treatment towards the epithelial cell turnover. Thus, CopA3 treatment shows its potential to inhibit the development of the early stages of AFB1-induced colon inflammation and hepatotoxicity in mice by inhibiting the DNA synthesis of the damaged and inflammatory cell and induced apoptosis for the clearance of damaged cells. Collectively, the results of this study suggest that CopA3 treatment may play a protective role against the mycotoxin induced inflammation.

Aflatoxin B₁ (AFB₁) is a hazard environmental pollutants and the most toxic one of all the aflatoxins. AFB₁ can cause a serious impairment to testicular development and spermatogenesis, yet the underlying mechanisms remain inconclusive. Oxidative stress acts as a master mechanism of AFB₁ toxicity, and can promote autophagy. Abnormal autophagy resulted in testicular damage and spermatogenesis disorders. The objective of this study was to explore the effect of AFB₁ on autophagy in mice testis and its potential mechanisms. In this study, male mice were intragastrically administered with 0, 0.375, 0.75 or 1.5 mg/kg body weight AFB₁ for 30 days. We found that AFB₁ induced testicular damage, reduced serum testosterone level and impaired sperm quality accompanied with the elevation of oxidative stress and germ cell apoptosis. Interestingly, we observed increasing numbers of autophagosomes in AFB₁-exposed mice testis. Meanwhile, AFB₁ caused testis abnormal autophagy with the characterization of increased expressions of LC3, Beclin-1, Atg5 and p62. Furthermore, AFB₁ downregulated the expressions of PI3K, p-AKT and p-mTOR in mice testis. Taken together, our data indicated AFB₁ induced testicular damage and promoted autophagy, which were associated with oxidative stress-related PI3K/AKT/mTOR signaling pathway in mice testis.

This study was conducted to investigate mycotoxin exposure in 260 rural residents (age 18–66 years) in Nanjing, China. Paired plasma and first morning urine samples were analyzed for 26 mycotoxin biomarkers, including 12 parent mycotoxins and 14 mycotoxin metabolites, by an ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method. Mycotoxins and their metabolites were detected in 95/260 (36.5%) plasma samples and 144/260 (55.4%) urine samples. The most prevalent mycotoxin in plasma was ochratoxin A (OTA), with the incidence of 27.7% (range 0.312–9.18 μg/L), while aflatoxin B₁-lysine (AFB₁-lysine) (incidence 19.6%, range 10.5–74.5 pg/mg albumin), fumonisin B₁ (FB₁) (incidence 2.7%, range 0.305–0.993 μg/L), deoxynivalenol (DON) (incidence 2.3%, range 1.39–5.53 μg/L), zearalenone (ZEN) (incidence 6.5%, range 0.063–0.418 μg/L) and zearalanone (ZAN) (incidence 1.2%, range 0.164–0.346 μg/L) were also detected in plasma samples. Deoxynivalenol-15-glucuronide (DON-15-GlcA) was the most frequently detected urinary mycotoxin, with the incidence of 43.8% (range 0.828–37.7 μg/L). DON (incidence 10.0%, range 1.39–14.7 μg/L), DON-3-glucuronide (DON-3-GlcA) (incidence 15.8%, range 0.583–5.84 μg/L), aflatoxin M₁ (AFM₁) (incidence 10.4%, range 0.125–0.464 μg/L), ZAN (incidence 7.7%, range 0.106–1.82 μg/L), ZEN (incidence 6.9%, range 0.056–0.311 μg/L), FB₁ (incidence 3.1%, range 0.230–1.33 μg/L), T-2 toxin (incidence 2.3%, range 0.248–3.61 μg/L) and OTA (incidence 1.2%, range 0.153–0.557 μg/L) were also found in urine samples. Based on the plasma or urinary levels, the daily intakes of AFB₁, FB₁, ZEN, DON and OTA were estimated. The results showed that the investigated rural dwellers were exposed to multiple mycotoxins, especially to carcinogenic mycotoxin AFB₁ with a mean daily intake of 0.41 μg/kg·bw/day, thereby underlining a potential public health concern. To the best of our knowledge, this is the first study to evaluate human exposure to mycotoxins with direct measurements of multiple mycotoxins in paired plasma and urine samples for over 200 subjects of a single population.

Polychlorinated biphenyls (PCBs) are persistent organic pollutants and hazardous to human health. Aflatoxin B1 (AFB1) is a strong carcinogen dependent on activation by cytochrome P450 (CYP) 1A2 and 3A4. Humans in some regions may be exposed to both PCBs and AFB1. Since PCBs are CYP inducers, we were interested in their combined genotoxicity. In this study, the effects of non-coplanar 2,3,3′-tri- (PCB 20), 2,2′5,5′-tetra- (PCB 52), 2,3,3′,4′-tetrachlorobiphenyl (PCB 56), and coplanar 3,3′,4,4′,5-pentachlorobiphenyl (PCB 126) on protein levels of CYP1A1, 1A2, and 3A4, and nuclear receptors AhR, CAR and PXR in a human hepatocyte (L-02) line were investigated. Moreover, the combined effects of each PCB and AFB1 for induction of micronuclei and double-strand DNA breaks (indicated by an elevation of γ-H2AX) were analyzed. The results indicated that PCBs 20, 52 and 56 reduced the expression of AhR, while elevated that of CAR and PXR, with thresholds at low micromolar concentrations. However, they were less potent than PCB 126, which was active at sub-nanomolar levels. Overexpression of human splice variant CAR 3 in the cells increased CYP1A2 and 3A4 levels, which were further enhanced by each non-coplanar PCB, suggesting a role of CAR in modulating CYPs. Pretreatment of cells with each test PCB potentiated both micronuclei formation and DNA damage induced by AFB1. This study suggests that both non-coplanar and coplanar PCBs may enhance the genotoxicity of AFB1, through acting on various nuclear receptors; the potentiation of AFB1 genotoxicity by PCBs and the potential health implications may deserve concerns and further investigation.

Aflatoxin B1 (AFB1) and microcystin-LR (MC-LR) simultaneously exist in polluted food and water in humid and warm areas, and each has been reported to be genotoxic to liver and associated with hepatocellular carcinoma (HCC). However, the genotoxic effects of the two biotoxins in combination and potential mechanism remain unknown. We treated the human hepatic cell line HL7702 with AFB1 and MC-LR together at different ratios, examined their genotoxic effects using micronuclei and comet assays, and evaluated the possible mechanism by measuring oxidative stress markers and DNA base excision repair (BER) genes. Our data show that co-exposure to AFB1 and MC-LR significantly increased DNA damage compared with AFB1 or MC-LR alone as measured by the levels of both micronuclei and tail DNA. Meanwhile, AFB1 and MC-LR co-exposure showed biphasic effects on ROS production, and a gradual trend towards increased Glutathione (GSH) levels and activity of Catalase (CAT) and Superoxide Dismutase (SOD). Furthermore, MC-LR, with or without AFB1, significantly down-regulated the expression of the base excision repair (BER) genes 8-oxoguanine glycosylase-1 (OGG1) and X-ray repair cross complementing group 1 (XRCC1). AFB1 and MC-LR in combination upregulated the expression of the BER gene apurinic/apyrimidinic endonuclease 1 (APE1), whereas either agent alone had no effect. In conclusion, our studies show that MC-LR exacerbates AFB1-induced genotoxicity and we report for the first time that this occurs through effects on oxidative stress and the deregulation of DNA base excision repair genes.

Mycotoxins are toxic metabolites of filamentous fungi; they are common contaminants in numerous foods and beverages. Cyclodextrins are ring-shaped oligosaccharides, which can form host-guest type complexes with certain mycotoxins. Insoluble beta-cyclodextrin bead polymer (BBP) extracted successfully some mycotoxins (e.g., alternariol and zearalenone) from aqueous solutions, including beverages. Therefore, in this study, we aimed to examine the ability of BBP to remove other 12 mycotoxins (including aflatoxin B1, aflatoxin M1, citrinin, dihydrocitrinone, cyclopiazonic acid, deoxynivalenol, ochratoxin A, patulin, sterigmatocystin, zearalanone, α-zearalanol, and β-zearalanol) from different buffers (pH 3.0, 5.0, and 7.0). Our results showed that BBP can effectively extract citrinin, dihydrocitrinone, sterigmatocystin, zearalanone, α-zearalanol, and β-zearalanol at each pH tested. However, for the removal of ochratoxin A, BBP was far the most effective at pH 3.0. Based on these observations, BBP may be a suitable mycotoxin binder to extract certain mycotoxins from aqueous solutions for decontamination and/or for analytical purposes.

Present study deals with the efficacy of nanoencapsulated Homalomena aromatica essential oil (HAEO) as a potent green preservative against toxigenic Aspergillus flavus strain (AF-LHP-NS 7), storage fungi, AFB₁, and free radical-mediated deterioration of stored spices. GC–MS analysis revealed linalool (68.51%) as the major component of HAEO. HAEO was encapsulated into chitosan nanomatrix (CS-HAEO-Ne) and characterized through SEM, FTIR, and XRD. CS-HAEO-Ne completely inhibited A. flavus growth and AFB₁ biosynthesis at 1.25 μL/mL and 1.0 μL/mL, respectively in comparison to unencapsulated HAEO (1.75 μL/mL and 1.25 μL/mL, respectively). CS-HAEO-Ne caused significant reduction in ergosterol content in treated A. flavus and provoked leakage of cellular ions (Ca⁺², Mg⁺², and K⁺) as well as 260 nm and 280 nm absorbing materials. Depletion of methylglyoxal level in treated A. flavus cells illustrated the novel antiaflatoxigenic efficacy of CS-HAEO-Ne. CS-HAEO-Ne exhibited superior antioxidant efficacy (IC₅₀ ₍DPPH₎ = 4.5 μL/mL) over unencapsulated HAEO (IC₅₀ ₍DPPH₎ = 15.9 μL/mL) and phenolic content. CS-HAEO-Ne depicted excellent in situ efficacy by inhibiting fungal infestation, AFB₁ contamination, lipid peroxidation, and mineral loss with acceptable sensorial profile. Moreover, broad safety paradigm (LD₅₀ value = 7150.11 mg/kg) of CS-HAEO-Ne also suggests its application as novel green preservative to enhance shelf life of stored spices.