Zearalenone

Zearalenone (ZEA), also known as RAL and F-2 mycotoxin, is a potent estrogenic metabolite produced by some Fusarium species.

Several Fusarium species produce toxic substances of considerable concern to livestock and poultry producers: namely, deoxynivalenol, T-2 toxin, HT-2 toxin, diacetoxyscirpenol (DAS) and zearalenone

Zearalenone is the primary toxin causing infertility, abortion or other breeding problems, especially in swine.

Zearalenone is heat-stable and is found worldwide in a number of cereal crops, such as maize, barley, oats, wheat, rice, and sorghum (Kuiper-Goodman et al., 1987; Tanaka et al., 1988a) and also in bread.

Chemical and physical properties
Zearalenone is a white crystalline compound, which exhibits blue-green fluorescence when excited by long wavelength UV light (360) and a more intense green fluorescence when excited with short wavelength UV light (260 nm). In methanol, UV absorption maxima occur at 236 (e =29,700), 274 (e =13,909) and 316 (e =6,020). Maximum fluorescence in ethanol occurs with irradiation at 314nm and with emission at 450nm. Solubility in water is about 0.002g/100ml. It is slightly soluble in hexane and progressively more so in benzene, acetonitrile, methylene chloride, methanol, ethanol and acetone. It is also soluble in aqueous alkali.

Sampling and analysis
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 or ethyl acetate followed by a range of different clean-up procedures that depend in part on the food and on the detection method in use. TLC methods and HPLC are commonly used. HPLC alone in not sufficient as it may often yield false positive results.

The TLC method for Zearalenone is: Normal phase silica gel plates, the eluent: 90% Dichloromethane, 10% v/v acetone; or Reverse phase C18 silica plates; the eluent: 90% v/v methanol, 10% water. Zearalenone gives unmistakable blue luminiscence under UV.