Biochemical Studies on Ochratoxin A
Ochratoxin A is one of three chemically related metabolites isolated from Aspergillus ochraceus Wilh. 1 It has been structurally characterised as 7-carboxyl-5-chloro-8-hydroxy-3,4-dihidro-methylisocoumarin linked over its 7-carboxyl group to L-β-phenylalanine.2 The LD50 in rats dosed per os is 20 mg/kg and the toxin causes enteritis, renal necrosis and an increase in the quantity of glycogen in rat liver.3 The route and time course of the metabolism of ochratoxin A was investigated by Nel and Purchase4 in view of the fact that the increase in glycogen only became evident 4 to 5 days after dosing. They concluded that ochratoxin A is hydrolysed in vivo to the isocoumarin moiety (ochratoxin α) most probably by proteolytic enzymes.
KeywordsProteolytic Enzyme Aromatic Amino Acid Glycogen Storage Disease Peptide Linkage Phenylpropionic Acid
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