Evaluation of toxicities of 7-hydroxyisotrichodermin and 8-hydroxyisotrichodermin, shunt intermediates in the biosynthetic grid of deoxynivalenol, by using a sensitive yeast assay

Abstract

  Fusarium graminearum causes a disease of wheat and barley known as Fusarium head blight. It contaminates the grains with trichothecene mycotoxins such as deoxynivalenol (DON). As shunt intermediates in the DON biosynthetic pathway, 7-hydroxyisotrichodermin (7-HIT) and 8-hydroxyisotrichodermin (8-HIT) are known. However, their activities have not been previously evaluated. In this study, we performed toxicity assays of these trichothecenes by using a sensitive yeast bioassay that we have recently established. The IC₅₀ of 7-HIT and 8-HIT were in the range of 20-40 μg/ml, while the IC₅₀ of DON was approximately 1.5 μg/ml. Although the toxicity of these shunt metabolites remains to be investigated in animal systems, our present data indicate that 7-HIT and 8-HIT may not be major issues that require regulation in agricultural products.