2.2.4. Cross-Reactivity of the Antisera with Zearalenone Derivatives

Inhibition of the antiserum by metabolites and structural analogues of ZON was also determined under optimized assay conditions. ZON is metabolized mostly through hydrolysis mainly to β- and α-zearalenol in yeast and ovine species, respectively [71,72]. Thus, IC<sup>50</sup> values by ZON metabolites and their reduced derivatives (α- and β zearalenol, α- and β-zearalanol, zearalanone) were determined in the immunoassay by absorbance and fluorescence and relative cross-reactivities (considering inhibition by ZON as 100%) are listed in Table 2. The results indicate that the antibodies appear to be most sensitive to the presence of the unsaturation in the resorcyclic lactone ring and exhibit lower affinity to hydroxy metabolites. Stereoconfiguration of the hydroxyl group also occurs to influence recognition.

**Table 2.** Percentage cross-reactivity (CR%) of the antiserum with zearalenone and its derivatives determined by fluorescence and absorbance.


1 IC50: half maximal inhibitory concentration; <sup>2</sup> CR%: Cross-reactivity defined as the percentage ratio of the IC<sup>50</sup> values of zearalenone and of the given derivative.
