Fumonisin B1, fumonisin B2, zearalenone and ochratoxin A contamination of maize in Croatia

The involvement of oxidative stress in ochratoxin A and fumonisin B1 toxicity in rats

The aim of this study was to find out whether very low doses of nephrotoxic and hepatotoxic mycotoxins ochratoxin A (OTA) and fumonisin B1 (FB1) induce oxidative stress in rat kidney and liver and whether their effect is synergistic. Rats were treated orally with OTA (5 ng/kg b.w. and 50 microg/kg b.w.) and FB1 (200 ng/kg b.w. and 50 microg/kg b.w.), or their combinations. Malondialdehyde (MDA) and protein carbonyls (PCs) concentration in kidney was affected with lower dose of OTA than in liver (p<0.05). FB1 did not affect MDA and PCs concentrations in the liver, while in the kidney both FB1 doses increased MDA concentration (p<0.05). The combination of the lower doses of OTA+FB1 increased the MDA and PCs concentration both in the liver and the kidney, compared to controls and animals treated with respective doses of mycotoxins (p<0.05). The combinations of mycotoxins reduced the catalase activity only in the kidney when compared to controls (p<0.05). In contrast to the increased kidney concentrations of MDA and PCs even with very low doses of OTA and FB1, the activity of catalase and SOD does not change. Combinations of OTA+FB1 affected almost all parameters, which indicates their potential to produce oxidative damage.

Cytotoxicity and apoptosis induced by fumonisin B1, beauvericin and ochratoxin A in porcine kidney PK15 cells: effects of individual and combined treatment

The objective of this study was to determine individual and combined effects of fumonisin B(1) (FB(1)), beauvericin (BEA) and ochratoxin A (OTA) on porcine kidney epithelial PK15 cell survival by measuring lactate dehydrogenase (LDH) activity, apoptotic index and caspase-3 activity. Cells were treated with 0.05, 0.5 and 5 microg/ml of each mycotoxin or with the combinations of two or all three mycotoxins for 24 and 48 h. Changes in LDH and caspase-3 activity, and in apoptotic index showed that the cytotoxic and apoptotic effects of these mycotoxins were concentration- and time- dependent. Significant increase of LDH activity was observed after 48 h of exposure to the highest concentration of FB(1) (45%), BEA (84%) and OTA (77%), as compared to control. OTA increased caspase-3 activity after 24 h of treatment with 0.5 mug/mL (84%), while BEA (319%) and FB(1) (419%) significantly affected this enzyme activity after 48 h (P < 0.05). Increase of caspase-3 activity preceded significant morphological apoptotic changes, which were detected after 48 h of exposure to a single toxin. Combined treatment with FB(1), BEA and OTA resulted mostly in additive effects on LDH activity, and additive and synergistic effects on caspase-3 activity and apoptotic index.

Occurrence of fumonisins B1and B2in Portuguese maize and maize-based foods intended for human consumption

Fumonisin B(1) (FB(1)) and fumonisin B(2) (FB(2)) are mycotoxins mainly produced by Fusarium verticillioides and Fusarium proliferatum, which are field pathogens of maize. A survey was conducted on the incidences of FB(1) and FB(2) in both maize and derived products purchased in Portugal. The analytical method involved extraction with methanol-water, clean-up by immunoaffinity column and derivatization with naphthalene-2,3-dicarboxaldehyde. Determination was carried out by high-performance liquid chromatography (HPLC) with spectrofluorimetric detection, with liquid chromatography/mass spectrometry (LC/MS) confirmation. The presence of FB(1) and FB(2) was determined in 67 samples of maize and maize-based foods, such as flour, semolina, starch, sweet maize, cornflakes and other breakfast cereals, and snacks collected in 2005. FBs were found in 15 samples at concentrations ranging from 113 to 2026 microg kg(-1). Two of the samples showed higher contamination levels than the limits established by the European Commission Regulation. None of the samples contained levels of fumonisins that would lead to an exposure exceeding the tolerable daily intake (TDI).

Lipid Peroxidation and Glutathione Levels in Porcine Kidney PK15 Cells after Individual and Combined Treatment with Fumonisin B1, Beauvericin and Ochratoxin A

Individual and combined effects of the mycotoxins fumonisin B(1), beauvericin and ochratoxin A on cell viability, lipid peroxidation (TBARS) and intracellular glutathione (GSH) were studied on porcine kidney epithelial cells (PK15). Cells were treated with 0.05, 0.5 and 5 microg/ml of each mycotoxin or the combinations of two or all three applied in equal concentrations for 24 and 48 hr. Changes in cell viability, GSH and TBARS levels showed that the cytotoxic effects of these mycotoxins were concentration- and time-dependent. After 24 hr, cell viability was significantly decreased by the exposure to 5 microg/ml of fumonisin B(1) (25%), beauvericin (30%) and ochratoxin A (35%), as compared to controls. Only ochratoxin A (5 microg/ml) increased TBARS (56%), with further significant increase (85%) after 48 hr exposure. Fumonisin B(1) and beauvericin significantly increased TBARS (57% and 80%, respectively) only when the highest dose was applied for 48 hr. After 24 hr, GSH was significantly decreased (18%) by ochratoxin A (0.05 microg/ml), whereas fumonisin B(1) and beauvericin significantly decreased GSH at the concentration of 0.5 microg/ml. Combined treatment with fumonisin B(1), beauvericin and ochratoxin A resulted mostly in additive effects especially after a 24-hr exposure, although synergistic as well as antagonistic interactions could not be excluded depending on toxin concentrations and time of exposure. This is the first report on beauvericin-induced effects on lipid peroxidation and GSH in animal cells.

Standard and Fpg-modified comet assay in kidney cells of ochratoxin A- and fumonisin B(1)-treated rats

The effect of ochratoxin A (OTA), fumonisin B(1) (FB(1)), and their combinations on DNA damage was studied using the standard alkaline comet assay and the Fpg-modified comet assay. Rats were orally receiving OTA (5 ng/kg b.w., 0.05 mg/kg b.w., and 0.5mg/kg b.w., respectively) for 15 days, FB(1) (200 ng/kg b.w., 0.05 mg/kg b.w., and 0.5mg/kg b.w., respectively) for 5 days, and the combinations of two lower OTA and FB(1) doses. The tail length, tail intensity, and Olive tail moment (OTM) obtained with the standard comet assay and Fpg-modified comet assay were significantly higher in treated animals than in controls, even at the lowest dose of OTA or FB(1) (p<0.01). The Fpg-modified comet assay showed significantly greater tail length, tail intensity, and OTM in all treated animal than did the standard comet assay (p<0.05), which suggests that oxidative stress is likely to be responsible for DNA damage. DNA damage detected by the standard comet assay at all OTA or FB(1) doses indicates that some other mechanism is also involved. Combined OTA+FB(1) treatment measured either by the standard comet or the Fpg-modified comet assay showed a synergistic increase in the tail intensity and OTM in kidney cells, even at doses that correspond to the daily human exposure in Europe.

Determination of fumonisins B1 and B2 in Portuguese maize and maize-based samples by HPLC with fluorescence detection

Fumonisins B(1) (FB1) and fumonisin B2 (FB2) are the main members of a family of mycotoxins produced by Fusarium verticillioides, Fusarium proliferatum, and other fungi species of the section Liseola. The present work shows the results of comparative studies using two different procedures for the analysis of fumonisins in maize and maize-based samples. The studied analytical methods involve extraction with methanol/water, dilution with PBS, and clean-up through immunoaffinity columns. Two reagents (o-phthaldialdehyde and naphthalene-2,3-dicarboxaldehyde) were studied for formation of fluorescent derivatives. The separation and identification were carried out by high-performance liquid chromatography with fluorescence detection. The optimized method for analysis of fumonisins in maize involved extraction with methanol/water (80:20), clean-up with an immunoaffinity column, and derivatization with naphthalene-2,3-dicarboxaldehyde (NDA). The limit of detection was 20 microg kg(-1) for FB1 and 15 microg kg(-1) for FB2. Recoveries of FB1 and FB2 ranged from 79% to 99.6% for maize fortified at 150 microg kg(-1) and 200 microg kg(-1), respectively, with within-day RSDs of 3.0 and 2.7%. The proposed method was applied to 31 samples, and the presence of fumonisins was found in 14 samples at concentrations ranging from 113 to 2,026 microg kg(-1). The estimated daily intake of fumonisins was 0.14 microg kg(-1) body weight per day.