Identification of ochratoxins and some of their metabolites in bile and urine of rats

The objectives of this study were to develop and evaluate procedures for the confirmation of ochratoxin A (OA), lactone opened OA (OP-OA), ochratoxin B (OB), hydroxy OA (OA-OH) and ochratoxin α (Oα) and metabolites formed in the rats from these toxins, and to demonstrate that many ochratoxin metabolites can be identified in the bile and urine of rats injected with the different ochratoxins. An esterification procedure in acidified methanol and a lactone hydrolysis procedure in strong base yielded two additional forms of most of the different ochratoxins. The esterification procedure provided a simple, fast and reliable method for the confirmation of the ochratoxins. A total of 20 different metabolites of OA, OP-OA, OB, OA-OH and Oα were detected in the urine and the bile of rats of which several were identified. Among these, OA and the recently discovered and toxic form of OA (OP-OA) were readily formed in vivo when either were injected. Procedures developed in this study can be used to confirm and isolate ochratoxins in biological samples and have shown that a new form of OA (OP-OA) along with many other metabolites are formed from OA and related ochratoxins in vivo.