Ochratoxin A and related mycotoxins

Ochratoxins are toxins produced by fungal species belonging not only to Aspergilli but also to Penicillia with ochratoxin A (OTA) being the main toxin of the group followed by ochratoxin B (OTB) and ochratoxin C (OTC). These mycotoxins can occurare formed in a variety of plant products as well as in some animal-derived products following fungal invasion. Human exposure to OTA is mainly due to contaminated cereal products, coffee and red wine. OTA it is continuously studied for its occurrence in different foods and feeds and for its harmfulness for human and animal health. OTA is immunotoxic, nephrotoxic and potentially carcinogenic in animals. Kidneys are its target organs and its level in foods is strictly regulated by laws with OTA being classified as a member of group 2B of carcinogens. According to the molecular structure, several enzymatic activities in addition to the primary pathway for phenylalanine biosynthesis are required for the biosynthesis of ochratoxin A: these are a polyketide synthase for the synthesis of the polyketide dihydroisocoumarin, a chlorinating enzyme, a methylase, an esterase, and a peptide synthetase for ligation of the phenylalanine to the dihydroisocoumarin.