Reactive products formed by peroxidase catalyzed oxidation of p-phenetidine.
The nature of the reactive metabolites formed during HRP/H2O2 catalyzed oxidation of p-phenetidine was investigated. Interaction with DNA measured as the induction of DNA single strand breaks and DNA binding resulted in a time-dependent decrease in the interaction and could be related to the primary oxidation of p-phenetidine. Oxygen uptake observed during p-phenetidine metabolism in the presence of GSH also exhibited such a correlation. GSH-conjugate formation and protein binding on the other hand exhibited an initial increase and did not appear to be directly related to primary p-phenetidine oxidation since maximal interaction was obtained when p-phenetidine had been completely metabolized. The GSH-conjugate and protein binding ratio of ring labelled to ethyl labelled p-phenetidine of approx. 2:1 indicated that these reactive metabolites(s) may be dimer(s) whose formation presumably involved loss of one ethoxy group of p-phenetidine. Accordingly formation of ethanol, indicative of ethoxy group elimination, could be observed during p-phenetidine metabolism. Only one metabolite generated from p-phenetidine oxidation exhibited a concentration dependent binding to protein. This metabolite also reacted with GSH to form water-soluble conjugates. Prior reduction of the metabolite by ascorbic acid prevented this conjugate formation. The mass spectral fragmentation pattern of the reactive protein- and GSH-binding metabolite was compatible with the structure N(4-ethoxyphenyl)-p-benzoquinoneimine.
D000627:Aminophenols / Q000378:metabolism*; D000818:Animals; D002250:Carbon Radioisotopes; D004247:DNA / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D005978:Glutathione / Q000494:pharmacology; D006735:Horseradish Peroxidase / Q000378:metabolism*; D007700:Kinetics; D013058:Mass Spectrometry; D010544:Peroxidases / Q000378:metabolism*; D010628:Phenetidine / Q000378:metabolism*; D011485:Protein Binding
D000627:Aminophenols; D002250:Carbon Radioisotopes; D010628:Phenetidine; D004247:DNA; D006735:Horseradish Peroxidase; D010544:Peroxidases; D005978:Glutathione