Trichothecenes

Trichothecenes are a very large family of chemically related mycotoxins produced by various species of Fusarium, Myrothecium, Trichoderma, Trichothecium, Cephalosporium, Verticimonosporium, and Stachybotrys. Trichothecenes belong to sesquiterpene compounds. The most important structural features causing the biological activities of trichothecenes are: the 12,13-epoxy ring, the presence of hydroxyl or acetyl groups at appropriate positions on the trichothecene nucleus and the structure and position of the side-chain. They are produced on many different grains like wheat, oats or maize by various Fusarium species such as F. graminearum, F. sporotrichioides, F. poae and F. equiseti.

Some molds that produce trichothecene mycotoxins, such as Stachybotrys chartarum, can grow in damp indoor environments. It has been found that macrocyclic trichothecenes produced by Stachybotrys chartarum can become airborne and thus contribute to health problems among building occupants. The poisonous mushroom in Japan and China, Podostroma cornu-damae contains six trichothecenes; satratoxin H, roridin E, verrucarin and others.

This group of structurally related mycotoxins has a strong impact on the health of animals and humans. Trichothecenes are powerful inhibitors of protein synthesis. They do this by reacting with components of the ribosomes: the structure within the cell where proteins are made. The specific site of action of T-2 toxin, which is a reaction with a critical site on the ribosomal RNA (rRNA), is known. Protein synthesis is an essential function in all tissues, but tissues where cells are actively and rapidly growing and dividing are very susceptible to the toxins. Trichothecenes are different from most other potential weapons toxins because they can act through the skin. Compared with some of the other mycotoxins such as aflatoxin, the trichothecenes do not appear to require metabolic activation to exert their biological activity. After direct dermal application or oral ingestion, the trichothecene mycotoxins can cause rapid irritation to the skin or intestinal mucosa. In cell-free systems or single cells in culture, these mycotoxins cause a rapid inhibition of protein synthesis and polyribosomal disaggregation. Thus, we can postulate that the trichothecene mycotoxins have molecular capability of direct reaction with cellular components. Despite this direct effect, it is possible to measure the toxicokinetics and the metabolism of the trichothecene mycotoxins.

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