Trichothecenes

Trichothecenes are a large family of chemically related mycotoxins produced by several species of fungi, most notably Fusarium species that infect cereal crops. They are sesquiterpenoid toxins characterized by a 12,13-epoxide ring, a structural feature essential for their biological activity. A common practical classification distinguishes Type A and Type B trichothecenes; Type A toxins lack a carbonyl group at certain positions, while Type B toxins contain a carbonyl group. Examples include Type A toxins T-2 toxin and HT-2 toxin, and diacetoxyscirpenol; Type B toxins include deoxynivalenol (DON, vomitoxin) and nivalenol.

Sources and occurrence: Trichothecenes occur in cereals, maize, barley, oats and derived products when Fusarium infects crops in the field or during storage. They are relatively stable to heat and processing, enabling persistence in flour, bread, beer and animal feeds. Humans and animals are exposed mainly by ingestion, with occupational exposure possible via handling contaminated grains.

Mechanism and toxicity: The toxins inhibit eukaryotic protein synthesis by binding to the ribosomal 60S subunit, blocking peptidyl transferase and triggering ribotoxic stress responses. This leads to impaired growth, gastrointestinal symptoms, immunosuppression and, at high doses, severe illness. Acute toxicity is well documented for certain trichothecenes; chronic, low-level exposure is a regulatory concern.

Regulation and management: Given their toxicity, trichothecenes are regulated in many countries, with maximum permissible levels in foods and feeds. Monitoring uses chromatographic methods; control measures include crop management, proper storage, sorting, and processing to reduce contamination.