Not only phase I reactions but also phase II reactions can be detected using embryonated chicken eggs as an alternative method for biotransformation studies. Previously reported investigations wich enabled the detection of the phase II products of 7-ethoxycoumarin in the allantois after enzymatic conjugate cleavage have since been supplemented by the development of a direct method. The glucuronidation and sulfation of p-nitrophenol were chosen as model reactions for this direct detection of conjugation reactions. The utility of the previously developed method for application to biotransformation investigations involving the detection of metabolites in the allantois in fertile chicken eggs has now been substantiated for the model substance p-nitrophenol. p-Nitrophenyl sulfate and p-nitrophenyl glucuronide were directly identified as phase II metabolites after incubation and work-up by HPLC analysis as well as comparison of their spectra with those of authentic substances. The conversion rates obtained are very high and well comparable with those of in vivo investigations in chickens. It would seem that the metabolism of hydrophilic substances can be advantageously studied in chicken eggs.

Not only phase I reactions but also phase II reactions can be detected using embryonated chicken eggs as an alternative method for biotransformation studies. Previously reported investigations which enabled the detection of the phase II products of 7-ethoxycoumarin in the allantois after enzymatic conjugate cleavage have since been supplemented by the development of a direct method. The glucuronidation and sulfation of p-nitrophenol were chosen as model reactions for this direct detection of conjugation reactions. The utility of the previously developed method for application to biotransformation investigations involving the detection of metabolites in the allantois in fertile chicken eggs has now been substantiated for the model substance p-nitrophenol. p-Nitrophenyl sulfate and p-nitrophenyl glucuronide were directly identified as phase II metabolites after incubation and work-up by HPLC analysis as well as comparison of their spectra with those of authentic substances. The conversion rates obtained are very high and well comparable with those of in vivo investigations in chickens. It would seem that the metabolism of hydrophilic substances can be advantageously studied in chicken eggs.

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-hydroxycomarin was observed after addition of 3-methylcholanthrene. The detected metabolites demonstrate the usefulness of the developed model for studying biotransformation processes.

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.