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 alpha), 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 characterized by 1H nuclear magnetic resonance spectroscopy, mass spectrometry and high-pressure liquid chromatography. 4-R-OH OA and O alpha were consistently 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 system. Green fluorescent biomacromolecules were isolated by detergent extraction of the fungal culture followed by cold-acetone precipitation and gel filtration. Acid hydrolysis of the fluorescent macromolecules resulted in the release of several ochratoxins, including O alpha (80%), OA (2%), and OC (5%), and other unidentified fluorescent compounds but not OB and O beta. Cross-reactivity studies of the natural macromolecule conjugates of OA with anti-OA polyclonal antibodies indicated that 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.
Xiao
H
H
Department of Animal Science, University of Manitoba, Winnipeg, Canada.
Marquardt
R R
RR
Abramson
D
D
Frohlich
A A
AA
D000818:Animals; D001235:Aspergillus ochraceus / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D046911:Macromolecular Substances; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D015394:Molecular Structure; D009793:Ochratoxins / Q000737:chemistry / Q000378:metabolism* / Q000652:urine*; D051381:Rats; D017207:Rats, Sprague-Dawley
D046911:Macromolecular Substances; D009793:Ochratoxins; C025589:ochratoxin A