AOZ [HRP]

1. The major metabolite resulting from the biotransformation of furaltadone (5-morpholinomethyl- 3-[5-nitrofurfurylidene-amino]-2-oxazolidinone) by pig hepatocytes was shown to result from the N-oxidation of the tertiary nitrogen in the morpholino-ring, leaving the nitrofuran ring unchanged. 2. No evidence could be obtained for the formation of an open-chain cyano-metabolite, a minor metabolite in the case of the related nitrofuran drug furazolidone (N-(5-nitro-2-furfurylidene)-3-amino-2-oxazolidinone). This metabolite was the major metabolite, following incubation of furaltadone and furazolidone with Salmonella typhimurium bacteria. 3. The N-oxide was not further metabolized by pig hepatocytes or bacteria, and gave negative test results in the Ames-test (TA 100, no S9-mix) at the highest tested dose of 1 mu g/plate. Furaltadone gave a positive result at 10 ng/plate. 4. The biotransformation of both drugs by pig hepatocytes and bacteria resulted in the formation of protein-bound metabolites, with no clear quantitative differences between the two drugs. The intact 3-amino-2-oxazolidinone (AOZ) and 5-morpholinomethyl-3-amino-2-oxazolidinone (AMOZ) side-chains of furazolidone and furaltadone, respectively, could be released from these metabolites by mild acid treatment. 5. Hepatocytes incubated with the AMOZ side-chain of furaltadone showed a decreased monoamine oxidase activity at high dose levels (IC50 3.7 mM), whereas exposure to the AOZ side-chain of furazolidone resulted in a clear inhibition at 10 000-fold lower concentrations (IC50 0.5 mu M). In the presence of 1% dimethylsulphoxide (DMSO), the MAO-inhibition by AMOZ and especially AOZ was remarkably reduced. 6. It is concluded that protein-bound metabolites containing an intact and releasable side-chain might be present in tissues of animals treated with furaltadone. However, these residues might be of less toxicological concern than those of furazolidone.

Existing clean up methods for HPLC determination of mycotoxins require separate analysis for aflatoxin, ochratoxin A, and zearalenone. Described is a method for simultaneous determination of aflatoxin, ochratoxin A, and zearalenone using one sample clean up and one HPLC run. A sample is extracted in aqueous methanol. The extract is diluted with buffer and passed over an immunoaffinity column containing immobilised antibodies to aflatoxin, ochratoxin A, and zearalenone (AOZ HPLC (TM) column). The column is then washed and eluted. Using gradient flow and wavelength switching for detection, aflatoxins, ochratoxin A and zearalenone were measured in a single HPLC run of less than 30 minutes. Recoveries for all toxins were greater than 80% from samples of spiked maize, sorghum and wheat over the range of 0-100 mu g/kg total aflatoxin, 0-1,000 mu g/kg zearalenone and 0-100 mu g/kg ochratoxin A. Analysis using multiple mycotoxin immunoaffinity columns can save time and money in performing the mycotoxin analysis required by many countries worldwide.