Mycotoxins vomitoxin toxicity

TRICHOTHECENE MYCOTOXINS. A family of structurally related poisonous substances produced by various species of fungi, especially Acremorium (Cephalosporium), Fusarium, Myrothe-cium, Stachybotrys, Trichderme, and Verticumonosporium. Tri-chothecene mycotoxins are toxic to humans because they inhibit cellular protein synthesis. Prominent examples are deoxynivalenol (sometimes referred to as vomitoxin because it induces vomiting), diacetoxyscirpenol, HT-2, nivalenol, and T-2. These five toxins gained some notoriety in the so-caUed yellow rain events in Southeast Asia because of allegations that they were associated with Soviet-inspired use of chemical weapons (CW). 

Of four basic trichothecene groups (A, B, C and D), types A and B represent the most important mycotoxins. Type A includes the T-2 toxin that can suppress the immune system and can cause damage to bone marrow. The T-2 toxin is about 14 times more toxic than the most widespread Fusarium-based type B mycotoxin, deoxynivalenol (DON), previously called vomitoxin. DON is a... 

Contamination occurs primarily in wheat, barley, rye, and maize. Type A trichothecenes include mainly T-2 toxin, HT-2, and diacetoxyscirpenol (DAS) mycotoxins of the group B include mainly 4-deoxynivalenol (DON), commonly known as vomitoxin, and nivalenol (NIV). Toxic effects include nausea, vomiting, visual disorder, vertigo, throat irritation, and feed refusal in farm animals. The most toxic is T-2, followed by DAS and NIV, with DON being the least toxic in acute toxicity studies but the most widespread in grains worldwide and therefore the most studied. Issues related to chemical and physical data, occurrence, toxicity, absorption, distribution, and metabolism of trichothecenes are reviewed in WHO (89) and IARC (34). Physicochemical data for some selected Fusarium toxins is given by Sydenham et al. (90). The molecular structures of the main trichothecenes are shown in Fig. 9. 

Other mycotoxins, including DAS, DON, and ochratoxin, are not of major economic importance although they can be toxic to food-producing animals. DAS causes necrosis and erosion of the oral mucous membranes. Consequently, affected animals exhibit feed refusal and have impaired growth. DON (also called vomitoxin ) induces vomiting and feed... 

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