Biochemical mechanism of action of mycotoxins

Symptoms of mycotoxicosis are a result of interactions of mycotoxins with functional molecules and subcellular organelles in the animal cell. The biological effects vary mainly according to the diversity in chemical structures of the mycotoxins, but also because of biological, nutritional and environmental factors. For a few myco— toxins, especially aflatoxin B1, so many effects on biochemical systems have been described that only a fraction could be discussed here. Many of these effects are probably secondary to one and the same primary mechanism of action, others occur at such high concentrations that they will never happen in nature. It is striking that so many mycotoxins act on the DNA—RNA level. In most cases this gives rise to consequences on many levels and with pathological pictures caused by many co-operating factors. Less frequently, the effects are as specific as the inhibition of phosphoenolpyruvate carboxykinase by ochratoxin A. Thus no generalized mechanism can apply to all myco— toxins not even for one and the same mycotoxin in different circumstances. The mechanism of action for a mycotoxin in mammalian cells may not be applicable to plants and microorganisms if metabolic activation is involved. Despite the many data accumulated so far, some of which have been accounted for in this review, the specific lesions responsible for the acute toxicity of many mycotoxins have not yet been identified. Much work therefore remains to be done in order to fully understand their mechanism of action.