Zearalenone (ZEN) and ZEN metabolites in feed, urine and bile of sows: analysis, determination of the metabolic profile and evaluation of the binding forms.

Abstract

A new alkaline-based method was developed for extracting zearalenone (ZEN) from feedstuffs. The procedure was shown to increase the extraction efficiency by 7 to 56 %. The addition of β-glucosidase did not increase the analyzed ZEN concentrationssuggesting ZEN-β-glucosides being of minor importance. Urine and bile samples from sows were analyzed by HPLC-FLD after treating the aqueous solution with β-glucuronidase/arylsulfatase and cleaning by liquid/liquid partition on a Kieselgur (Extrelut® ) column and IA-chromatography. A recovery of 82 to 99 % for ZEN, α- and β-zearalenol (α- and β-ZEL) was determined. ZEN and α-ZEL concentrations in bile samples from an experiment with sows fed with ZEN contaminated diets increased significantly with the ZEN concentration of the feed. In urine, such a dependency was found only for α-ZEL. The proportion of α-ZEL of the sum of ZEN and its metabolites (α- and β-ZEL) increased from 42 to 53 % in bile and from 27 to 49 % in urine (without control groups) with dietary ZEN concentrations, respectively. ZEN and its metabolite α-ZEL were nearly exclusively conjugated to glucuronic acid or sulfuric acid in bile and urine. The percentage of the free, ZEN and α-ZEL varied between 1 and 6 %. The proportion of glucuronidated conjugates of ZEN in bile as well as in urine of sows was >95 % and no sulfated conjugates were present. The relation of glucuronidated to sulfated conjugates of α-ZEL was 82 to 17 % in bile, whereas in urine the sulfated (62 %) form of α-ZEL was predominant to the glucuronidated (33 %) form.