METABOLITES OF OCHRATOXINS IN RAT URINE AND IN A CULTURE OF ASPERGILLUS-OCHRACEUS

We studied the metabolic profile of ochratoxin A (OA) in rats and in a culture of OA-producing Aspergillus ochraceus. Ochratoxin alpha (O al pha), ochratoxin beta (O beta), 4-R-hydroxyochratoxin A (4-R-OH OA), 4 -R-hydroxyochratoxin B (4-R-OH OB), and 10-hydroxyochratoxin A (10-OH OA) were isolated from a culture of A. ochraceus and structurally char acterized by H-1 nuclear magnetic resonance spectroscopy, mass spectro metry and high-pressure liquid chromatography, 4-R-OH OA and Oa were c onsistently produced and were the dominant biotransformed metabolites in the fungal culture and in rats treated with OA and ochratoxin C (OC ), while the formation of 10-OH OA was conditional in the fungal syste m. Green fluorescent biomacromolecules were isolated by detergent extr action of the fungal culture followed by cold-acetone precipitation an d gel filtration. Acid hydrolysis of the fluorescent macromolecules re sulted in the release of several ochratoxins, including O alpha (80%), OA (2%), and OC (5%), and other unidentified fluorescent compounds bu t not OB and O beta. Cross-reactivity studies of the natural macromole cule conjugates of OA with anti-OA polyclonal antibodies indicated tha t they were covalently linked to the macromolecules via a group other than the carboxyl group. These studies demonstrated that a fungus can produce some of the same metabolites of OA as the rat and that O alpha , OA, and OC may be covalently linked to fungal macromolecules.