Zearalenone is heat-stable and is found worldwide in a number of cereal crops, such asmaize,barley,oats,wheat,rice, andsorghum.[6][7][8] Its production increases when the climate is warm with air humidity at or above twenty percent.[4] The environmental pH plays also a role in the toxin's production. When temperatures fall to 15°C, alkaline soils still support ZEN production. At the preferredFusarium temperature, which ranges between 25°C and 30°C, neutral pH results in the greatest toxin production.[9]
In addition to its actions on the classicalestrogen receptors, zearalenone has been found to act as anagonist of theGPER (GPR30).[8]
Zearalenone is a whitecrystalline solid, with molecular formula C18H22O5 and 318.364 g/mol molecular weight. It is aresorcyclic acid lactone. It exhibits blue-greenfluorescence when excited by long wavelengthultraviolet (UV) light (360 nm) and a more intense green fluorescence when excited with short wavelength UV light (260 nm).[4] In methanol, UV absorption maxima occur at 236 (e = 29,700), 274 (e = 13,909) and 316 nm (e = 6,020). Maximum fluorescence inethanol occurs with irradiation at 314 nm and with emission at 450 nm. Solubility in water is about 0.002 g/100 mL. It is slightly soluble inhexane and progressively more so inbenzene,acetonitrile,methylene chloride,methanol,ethanol, andacetone. It is also soluble in aqueousalkali.[citation needed]
The naturally occurringisomertrans-zearalenone (trans-ZEN) is transformed by ultraviolet irradiation tocis-zearalenone (cis-ZEN).[10]
Zearalenone is metabolically transformed to α-zearalenol (α-Zel) or (α-Zol), β-zearalenol (β-Zel) or (β-Zol), α-zearalanol (α-Zal), β-zearalanol (β-Zal), and zearalanone (ZAN) in animals.[9][11] The relative composition of these metabolic products varies by species. In pigs, cows and ducks, α-Zel is the dominant form detected.[12][13][4] In humans, both α-Zel and β-Zel are seen in urine samples, with the beta form being prevalent.[14] In chickens, β-Zel is the dominant form and in plant cells, the metabolic product zeralenonne-14-O-β-glucoside has been detected.[4] Additionally, in the organs of animals these metabolic products are further modified to yield zearalenone-14-glucuronide (ZEN-14GlcA), α-zearalenol-glucuronide (α-Zel-14G) and β-zearalenol-glucuronide (β-Zel-14G).[15]
Zearalenone can permeate through the human skin.[16] However, no significant hormonal effects are expected after dermal contact in normal agricultural or residential environments.
Zearalenone structure is similar toestrogens and α-zearalenol binds with an even greater affinity estrogen receptors, while β-zearalenol's affinity is lower than both the parent compound's and α-Zel's binding affinity.[4] This identifies ZEN and its metabolites asxenoestrogens.[3] The human and livestock exposure to ZEN through the diet poses health concern due to the onset of severalsexual disorders and alterations in the development ofsexual organs.[17][18] There are reliable case reports of early puberty in girls chronically exposed to ZEN in various regions of the world.[19] In mice, ZEN consumption was linked to a decline of potent sperm and egg cells, an increase to double-stranded breaks in DNA and activation of DNA repair mechanisms, followed by embryonic development challenges that reduced the viability of offspring.[11]
In common with other mycotoxins, sampling food commodities for zearalenone must be carried out to obtain samples representative of the consignment under test. Commonly used extraction solvents are aqueous mixtures of methanol,acetonitrile, orethyl acetate followed by a range of different clean-up procedures that depend in part on the food and on the detection method in use.Thin-layer chromatography (TLC) methods andhigh-performance liquid chromatography (HPLC) are commonly used. The TLC method for zearalenone is: normal phasesilica gel plates, the eluent: 90%dichloromethane, 10% v/v acetone; or reverse phase C18 silica plates; the eluent: 90% v/vmethanol, 10% water. Zearalenone gives unmistakable blue luminiscence under UV.[1] HPLC alone is not sufficient, as it may often yield false positive results. Today, HPLC-MS/MS analysis is used to quantify and confirm the presence of zearalenone.
Typically, the representative sample is commuted and homogenized then few grams are used for extraction with acetonitrile/water mixture. The procedure is the widely usedQuEChERS method that quickly and effectively extracts small molecules, like mycotoxins and pesticides, from complex food matrices and animal tissues. The determination step relies onliquid chromatography - mass-spectrometry (LC-MS/MS).[15] Another approach for the analysis of ZEA, without the requirement of expensive instrumentation, is developing specificpeptide mimetic with thebioluminescentGaussialuciferase fused as one protein that can bind specifically to ZEA.[20]
^Kuiper-Goodman T, Scott PM, Watanabe H (September 1987). "Risk assessment of the mycotoxin zearalenone".Regulatory Toxicology and Pharmacology.7 (3):253–306.doi:10.1016/0273-2300(87)90037-7.PMID2961013.
^Tanaka T, Hasegawa A, Yamamoto S, Lee US, Sugiura Y, Ueno Y (1988). "Worldwide Contamination of Cereals by theFusarium Mycotoxins Nivalenol, Deoxynivalenol, and Zearalenone. 1. Survey of 19 Countries".Journal of Agricultural and Food Chemistry.36 (5). American Chemical Society:979–983.Bibcode:1988JAFC...36..979T.doi:10.1021/jf00083a019.
^Brezina U, Kersten S, Valenta H, Sperfeld P, Riedel J, Dänicke S (November 2013). "UV-induced cis-trans isomerization of zearalenone in contaminated maize".Mycotoxin Research.29 (4):221–227.doi:10.1007/s12550-013-0178-7.PMID24018604.S2CID17466231.
^abYang D, Jiang X, Sun J, Li X, Li X, Jiao R, et al. (September 2018). "Toxic effects of zearalenone on gametogenesis and embryonic development: A molecular point of review".Food and Chemical Toxicology.119:24–30.doi:10.1016/j.fct.2018.06.003.PMID29864477.S2CID46927149.
Eriksen GS, Pennington J, Schlatter J (2000)."Zearalenone".WHO International Programme on Chemical Safety - Safety Evaluation of Certain Food Additives and Contaminants. Inchem. WHO Food Additives Series.
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