Results differs from those obtained in
the present study, in which a-ZAL was detected in 30.9% (mean
3.6 ng mL1) and ZON and b-ZAL in 1.8% and 3.6% of the samples,
respectively, whereas a-ZOL, b-ZOL and ZAN were not found in
any of the analyzed samples.
Our higher mean concentration of
a-ZAL could be explained by the fact that we determined total content
while Bandera et al. determined free content.
On the other
hand, it is unclear whether a-ZAL derives from the metabolism
of ZEN or from consumption of contaminated meat because.a-ZAL can been detected in the final product when used as a
growth promoter for livestock (Stephany and Adré, 1999).
Once
ingested, a-ZAL could be metabolized into its diasteromer b-ZAL
and, to a lesser extent into ZAN and conjugated with sulfonic or
glucuronic acid.
This reduces bioactivity, as only free forms are biologically
active, and facilitates urinary excretion.