Zearalenone Mycotoxin

Zearalenone (ZEA), also referred to as F-2 toxin, is a mycotoxin produced as a secondary metabolite by numerous species of Fusarium. It is one of the most important mycotoxins that include aflatoxins-AF (B1, B2, G1, G2), Ochratoxin A (OTA), fumonisins (FB1, FB2), and trichothecenes (deoxynivalenol-DON, T-2, HT-2). Fusarium species are known to infest wheat, barley, rice, maize, and other crops, resulting in the contamination of human foods and animal feed. ZEA and its metabolites have a toxic effect because their structure and shape resembles that of natural estrogens, such as estradiol, estrone, and estriol. ZEA is a stable compound during both storage/milling and the processing/cooking of food, as indicated by its presence in some grain products, such as bread, beers, and processed feeds.

Zearalenone

Natural exposure to ZEA in contaminated food has been implicated as a cause of female reproductive changes as a result of its powerful estrogenic activity: its hormonal action exceeds that of most other naturally occurring non-steroidal phytoestrogens, including soy and clover isoflavones. There are reliable case reports of early puberty in girls chronically exposed to zearalenone.1, 2 ZEA has the ability to bind to estrogen receptors and induces estrogenic syndromes including uterine enlargement, swelling of the vulva and mammary glands, and false pregnancy through the intake of contaminated grains. Moreover, zearalenone affects not only puberty and estrous cyclicity but also early pregnancy events, including fertilization, embryo development, embryo transport, and embryo implantation. Alpha-zearalenol (one of zearalenone metabolites) was also detected in the serum of patients with endometrial cancer.4 For this reason, risks of ZEA contamination is of international concern, and has become a substantial problem in beer production.3


Zearalenone and its metabolites demonstrate genotoxic activity (are mutagens) which results in DNA replication disruptions and changes in the structure or number of chromosomes. Every change in the DNA nucleotide sequence leads to mutations. Although some mutations are symptom-free, they exert an effect on the body. There exists a close link between mutations and the formation of cancer cells. Many mutagens are carcinogens, which means they are factors that contribute to the formation of cancers.2

Besides foods and feeds, inhalation is another route of exposure to zearalenone. Estrogens have been shown to induce proliferation of non-small cell lung cancer. Exposure to ZEA may increase susceptibility of bronchial epithelial cells to diseases such as asthma and Chronic Obstructive Pulmonary Disease.5

Among animals, pigs are the most sensitive species to ZEA, and the main toxicities of ZEA and its metabolites. Zearalenone induces hyperestrogenism in pigs, with typical clinical symptoms including swollen vulva, vaginal prolapsed, as well as reproductive disorders such as infertility, miscarriage and false estrus in sows.6

References

  1. Zearalenone, an Estrogenic Mycotoxin, Is an Immunotoxic Compound
  2. Determination of zearalenone and its metabolites in endometrial cancer by coupled separation techniques
  3. Metabolism of Zearalenone in the Course of Beer Fermentation
  4. Postweaning Exposure to Dietary Zearalenone, a Mycotoxin, Promotes Premature Onset of Puberty and Disrupts Early Pregnancy Events in Female Mice
  5. Gene Expression Profile and Toxic Effects in Human Bronchial Epithelial Cells Exposed to Zearalenone
  6. Zearalenone Altered the Serum Hormones, Morphologic and Apoptotic Measurements of Genital Organs in Post-weaning Gilts

 

 

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