[Biotransformation processes in fertile hen's eggs. 1. Metabolic transformation of 7-ethoxycoumarin]

An alternative method for the investigation of biotransformations employing fertile chicken eggs has been developed. In these studies, solutions of 7-ethoxycoumarin were injected into the white of eggs from a standardized breed after brooding time of at least 8 days. After further incubation, the allantois was analyzed for metabolites of 7-ethoxycoumarin. The dealkylated metabolite of 7-ethoxycoumarin, namely 7-hydroxycoumarin, could be assayed in the allantois liquid by means of a new HPLC method. Furthermore, conjugates of 7-hydroxycoumarin, namely the glucuronid and the sulfate, can be detected indirectly in the allantois after conjugate cleavage. The inducability of the cytochrome P-450-dependent O-dealkylation has been studied with phenobarbital and 3-methylcholanthrene. An increase in the conversion of 7-ethoxycoumarin to 7-hydroxycoumarin was observed after addition of 3-methylcholanthrene. The detected metabolites demonstrate the usefulness of the developed model for studying biotransformation processes.