Fusarium Toxins

What are Fusarium toxins

Fusarium toxins are synthesised mainly by moulds of the genus Fusarium which are present in the natural microflora of topsoil. Living crops especially cereals and maize are often infested with Fusarium before harvesting. These typical field fungi need a high water activity for development and under favourable conditions may even spread during storage. The synthesised mycotoxins of Fusarium in harvested goods are classified in three major groups, the trichothecenes, the fumonisines and zearalenone.

Trichothecenes

The trichothecenes have very differing chemical structures and are therefore classified into four subgroups. The type A- and B-trichothecenes are the most common. The most important representatives of type A-trichothecenes are the T2-toxin, the HT2-toxin and diacetoxyscirpenol. These are typical in cereals, maize, bananas and potatoes. Particularly significant is the presence of T2- and HT2-toxin in oats and oat products. Comprising the type B-trichothecenes are deoxynivalenol (DON), nivalenol and their respective precursors of biosynthesis, 3- or 15-acetyldeoxynivalenol and fusarenon X. Deoxynivalenol and nivalenol are currently the most important mycotoxins in cereal and maize cultivation.

Fumonisines

Fumonisines are ubiquitous, highly polar mycotoxins which have a very similar chemical structure. Often they are detected in maize. So far, six fumonisines are known (FB1 to FB4, FA1, FA2) which due to their similar structure interfere with biosynthesis of sphingosin, a constituent of the cell membranes. The most common fumonisines are the fumonisines B1 and B2.

Zearalenone

Zearalenone is a common mycotoxin among the Fusarium toxins. Chemically zearalenone is a macrolactone derivative. It is synthesised in harvested goods like maize, cereals and even bananas by a number of different Fusariums. These are mostly the same which are responsible for synthesis of deoxynivalenol. Zearalenone has a distinct estrogenic effect.

Deoxynivalenol

Deoxynivalenol (DON), also known as vomitoxin, is a type of mycotoxin produced by certain species of Fusarium fungi. The toxin frequently contaminates cereal grains such as wheat, barley, oats, rye, and maize. DON-contaminated food products can cause stomach pain, dizziness, headaches, coughing, nausea, vomiting and diarrhea in humans.

DON is very stable during storage, technological processing and exposure to high temperatures. Avoidance strategies therefore lie in the agricultural sector (e.g. avoidance of maize as a preceding crop) or in reduction during processing (e.g. cleaning step in grain processing).