Occurrence of zearalenone in Korean barley and corn foods

Effects of Panax ginseng, zearalenol, and estradiol on sperm function

BACKGROUND

Estrogen signaling pathways are modulated by exogenous factors. Panax ginseng exerts multiple activities in biological systems and is classified as an adaptogen. Zearalenol is a potent mycoestrogen that may be present in herbs and crops arising from contamination or endophytic association. The goal of this study was to investigate the impact of P. ginseng, zearalenol and estradiol in tests on spermatozoal function.

METHODS

The affinity of these compounds for estrogen receptor (ER)-alpha and beta (ERα and ERβ)-was assessed in receptor binding assays. Functional tests on boar spermatozoa motility, movement and kinematic parameters were conducted using a computer-assisted sperm analyzer. Tests for capacitation, acrosome reaction (AR), and chromatin decondensation in spermatozoa were performed using microscopic analysis.

RESULTS

Zearalenol-but not estradiol (E2)- or ginseng-treated spermatozoa-decreased the percentage of overall, progressive, and rapid motile cells. Zearalenol also decreased spontaneous AR and increased chromatin decondensation. Ginseng decreased chromatin decondensation in response to calcium ionophore and decreased AR in response to progesterone (P4) and ionophore.

CONCLUSION

Zearalenol has adverse effects on sperm motility and function by targeting multiple signaling cascades, including P4, E2, and calcium pathways. Ginseng protects against chromatin damage and thus may be beneficial to reproductive fitness.

Zearalenone contamination in barley, corn, silage and wheat bran

Zearalenone (ZEN) is a nonsteroidal estrogen mycotoxin produced by Fusarium graminearum and other Fusarium species, which are plant pathogenic fungi that infect many plants and their products, including corn, barley, fruits and vegetables. This study presents the results of a survey for ZEN contamination on barley, corn, silage and wheat bran. A total of 54 samples were collected from Shahrekord in spring and summer 2010, including 20 barley, 8 corn, 12 silage and 14 wheat bran and analyzed using direct competitive enzyme-linked immunosorbent assay. From 54 samples analyzed, ZEN was found in 8 samples (14.8%), with a mean level of 142 ng/g. Corn had the highest incidence of ZEN (25.0%), followed by barley (20.0%) and silage (16.7%). No ZEN was detected in any wheat bran samples. The results of this study show that ZEN-exposed corn, barley, silage and wheat bran would not be a health concern in animals.

Development and validation of a gold nanoparticle immunochromatographic assay (ICG) for the detection of zearalenone

A monoclonal antibody (mAb)-based gold nanoparticle immunochromatographic assay (ICG) for zearalenone detection was developed, optimized, and validated. The detection limits of ICG optimized with appropriate amounts of zearalenone-bovine serum albumin and gold nanoparticle-mAb to zearalenone were 2.5 ng/mL and 30 μg/kg for the standard solution and spike sample, respectively, and a weak cross-reaction for α-zearalenol and β-zearalenol was observed. The assay required only 15 min to obtain results and one step to perform the assay. In validation, the results obtained from spiked corn (10, 20, 30, 50, and 100 μg/kg) and naturally contaminated corn samples by the ICG were in good agreement with those obtained by direct competitive enzyme-linked immunosorbent assay (DC-ELISA) and high-performance liquid chromatography (HPLC). Therefore, the results obtained in this study could be used as basic research for the development of zearalenone-ICG, and the ICG developed could be a useful on-site screening tool for the rapid detection of zearalenone in corn without special instrumentation.

Fungal mycoflora and mycotoxins in Korean polished rice destined for humans

Rice samples collected from the Republic of Korea were analyzed for fungal mycoflora and mycotoxins: fumonisins, ochratoxin A, trichothecenes, and zearalenone. The potential of the fungi to produce each mycotoxin was also examined, so that the fungal isolates associated with mycotoxins occurring in rice could be verified. Penicillium citrinum and Aspergillus candidus were the most prevalent species infecting the samples, while Fusarium proliferatum was found as the dominant Fusarium species. Ochratoxin A was the most commonly detected mycotoxin analyzed in the present study; moreover, its level in some samples was above the EU tolerable limit (3 ng/g). According to rice culture experiments, it was revealed that in Korea, fumonisins detected in rice were due to F. proliferatum infection, whereas the occurrence of ochratoxin A was caused by Penicillium verrucosum, though there were no symptoms of disease in rice found in any sample. Furthermore, there appears to be an uneven geographical distribution of P. verrucosum as well as ochratoxin A in that most of them are found in the rice samples produced in the northern region of Korea.

Determination of zearalenone in corn flour and a cheese snack product using high-performance liquid chromatography with fluorescence detection

The presence of the mycotoxin zearalenone in corn flour and a cheese snack derived from this was determined. Thirty-eight samples (corn flour and cheese snacks) of different brands were analysed for zearalenone using high-performance liquid chromatography with fluorescence detection. Zearalenone was detected in corn flour and cheese snack samples with average content of 0.377 pm (maximum, 0.889 pm) and 0.832 pm (maximum, 1.471 ppm) respectively. The recovery from spiked corn flour and cheese snack samples ranged from 70-87%. The method had a limit of detection of 0.01 microg ml(-1). The linearity of method was determined (y=5.88 x 0.25, r(2)=0.9999), and optimum assay range was 0.05-30 microg ml(-1). The occurrence of zearalenone in the maize product confirms the need to assess the exposure of the Iranian population to this mycotoxin.

Survey of Fusarium toxins in foodstuffs of plant origin marketed in Germany

A total of 219 samples of foodstuffs of plant origin, consisting of grain-based food, pseudocereals and gluten-free food as well as vegetables, fruits, oilseeds and nuts, were randomly collected during 2000 and 2001 in food and health food stores. A spectra of 13 trichothecene toxins including diacetoxyscirpenol (DAS), 15-monoacetoxyscirpenol (MAS), scirpentriol (SCIRP), T-2 and HT-2 toxins (T-2, HT-2), T-2 triol, T-2 tetraol, neosolaniol (NEO) of the A-type as well as deoxynivalenol (DON), 3- and 15-acetyl-DON (3-, 15-ADON), nivalenol (NIV), and fusarenon-X (FUS-X) of the B-type were determined by gas chromatography/mass spectrometry. Analysis of zearalenone (ZEA), alpha- and beta-zearalenol (alpha- and beta-ZOL) was made by high-performance liquid chromatography with fluorescence and UV-detection. Detection limits ranged between 1 and 19 microg/kg. Out of 84 samples of cereal-based including gluten-free foods, 60 samples were positive for at least one of the toxins DON, 15-ADON, 3-ADON, NIV, T-2, HT-2, T-2 tetraol and ZEA, with incidences at 57%, 13%, 1%, 10%, 12%, 37%, 4% and 38%, respectively, whereas SCIRP and its derivatives MAS and DAS, T-2 triol, Fus-X as well as alpha- and beta-ZOL were not detected in any sample of this subgroup. Contents of DON ranged between 8 and 389 microg/kg, for all other toxins determined concentrations were below 100 microg/kg. The pseudocereals amaranth, quinoa and buckwheat were free of the toxins investigated. Ten of 85 samples of vegetables and fruits were toxin positive. ZEA and the type A trichothecenes MAS, SCIRP, DAS, HT-2 were detected in 7, 3, 2, 1 and 1 samples, respectively. Out of 35 samples of oilseeds and nuts, 7 samples were toxin positive. HT-2, T-2 and ZEA were detected in 4, 3 and 4 samples, respectively. In vegetables and fruits as well as in oilseeds and nuts, toxin levels were below 50 microg/kg. None of the B-type trichothecenes analysed was found for both subgroups.

Detection of zearalenone and related metabolites by fluorescence polarization immunoassay

Zearalenone is an estrogenic mycotoxin commonly found in grains throughout the world. A number of instrument- and antibody-based methods including enzyme-linked immunosorbent assays (ELISAs) have been developed to detect zearalenone (ZEN) and related toxins in commodities and foods. Although convenient, the commercial ELISAs for small molecules such as ZEN require a washing step to separate bound and unbound enzyme label before detection. In fluorescence polarization immunoassays, separation of bound and unbound label is not required, a property that reduces the time needed to perform the assays. We developed a fluorescence polarization immunoassay for ZEN in maize. When combined with a rapid extraction technique, the assay could be used to detect as little as 0.11 microg of ZEN g(-1) maize within 10 min. The assay showed cross-reactivity to the ZEN analogs zearalanone, alpha-zearalanol, alpha-zearalenol, beta-zearalenol, and beta-zearalanol of 195, 139, 102, 71, and 20%, respectively, relative to ZEN (100%). Recovery of ZEN from spiked maize over the range of 0.5 to 5 microg g(-1) averaged 100.2% (n = 12). The fluorescence polarization immunoassay results were comparable to those obtained with a liquid chromatographic method for the analysis of 60 naturally contaminated maize samples and maize samples amended with culture material. The fluorescence polarization immunoassay provides a rapid method for screening of maize for ZEN.

Natural co-occurrence of aflatoxin B1, fumonisin B1 and ochratoxin A in barley and corn foods from Korea

A survey for aflatoxin B1 (AFB1), fumonisin B1 and ochratoxin A (OTA) was conducted on 127 samples that included 30 food-grade barley, 32 barley foods, 18 food-grade corn and 47 corn foods, randomly collected during 1998-99 in Seoul, Korea. The presence of mycotoxins was analysed by direct competitive enzyme-linked immunosorbent assay (ELISA), and most of the positive samples from ELISA were confirmed using high-performance liquid chromatography (HPLC). Recoveries of AFB1 and OTA spiked at 10 ng g(-1) and FB1 spiked at 50 ng g(-1) were 106, 87 and 105% by ELISA, whereas those by HPLC were 80, 79 and 84%, respectively. Detection limits by ELISA for AFB1, FB1 and OTA were 1, 5 and 5 ng g(-1), and those by HPLC were 0.6, 35 and 1 ng g(-1). Naturally occurring AFB1, FB1 and OTA were found in 4/32 (12%), 2/32(6%) and 4/32 (12%) samples of barley foods with an average of 26, 16 and 9 ng g(-1), respectively. AFB1 and FB1 in corn foods were detected in 4/47 (8%) and 9/47 (19%) samples with the average being 20 and 74 ng g(-1), while no OTA was found in any corn foods samples. No AFB1, FB1 or OTA was detected in any of food-grade barley and corn samples. This is the first report on the natural co-occurrence of AFB1 and FB1 in barley and corn foods as well as on surveillance of OTA in Korea.