Transformation of zearalenone and zearalenol by rat erythrocytes.

The interconversion of zearalenone and zearalenol by rat erythrocytes in vitro has been investigated. The major metabolite obtained by incubating zearalenone with erythrocytes or whole blood from Sprague-Dawley rats was alpha-zearalenol. beta-Zearalenol was also formed but at levels several times lower than those of alpha-zearalenol. In the cell-free haemolysate NADPH was much more effective than NADH as a co-factor in the reduction of zearalenone. The maximal transformation of zearalenone to zearalenol by haemolysates occurred at pH 8.0. Both NAD+ and NADP+ were effective as co-factors in the oxidation of alpha-zearalenol to zearalenone. However, only NADP+ was effective as a co-factor in the oxidation of beta-zearalenol. Conversion of alpha-zearalenol and beta-zearalenol to the corresponding epimer was observed in both erythrocyte suspensions and in cell-free haemolysates. The significance of these findings to the metabolism of zearalenone in vivo is discussed.