These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Mechanisms of acetaminophen oxidation to N-acetyl-P-benzoquinone imine by horseradish peroxidase and cytochrome P-450.
    Author: Potter DW, Hinson JA.
    Journal: J Biol Chem; 1987 Jan 25; 262(3):966-73. PubMed ID: 3805031.
    Abstract:
    Horseradish peroxidase rapidly catalyzed the H2O2-dependent polymerization of acetaminophen. Acetaminophen polymerization was decreased and formation of GSSG and minor amounts of GSH-acetaminophen conjugates were detected in reaction mixtures containing GSH. These data suggest that horseradish peroxidase catalyzed the 1-electron oxidation of acetaminophen and that GSH decreased polymerization by reducing the product, N-acetyl-p-benzosemiquinone imine, back to acetaminophen. Analyses of reaction mixtures that did not contain GSH showed N-acetyl-p-benzoquinone imine formation shortly after initiation of reactions. When GSH was added to similar reaction mixtures at various times, 3-(glutathion-S-yl)-acetaminophen was formed. The formation and disappearance of this product were very similar to N-acetyl-p-benzoquinone imine formation and were consistent with the disproportionation of 2 mol of N-acetyl-p-benzosemiquinone imine to 1 mol of N-acetyl-p-benzoquinone imine and 1 mol of acetaminophen followed by the rapid reaction of N-acetyl-p-benzoquinone imine with GSH to form 3-(glutathion-S-yl)acetaminophen. When acetaminophen was incubated with NADPH, oxygen and hepatic microsomes from phenobarbital-pretreated rats, 1.2 nmol 3-(glutathion-S-yl)acetaminophen/nmol cytochrome P-450/10 min was formed. Formation of polymers was not observed indicating that N-acetyl-p-benzoquinone imine was formed via an overall 2-electron oxidation rather than a disproportionation reaction. However, when cumene hydroperoxide was replaced by NADPH in microsomal incubations, polymerization was observed suggesting that cytochrome P-450 might also catalyze the 1-electron oxidation of acetaminophen.
    [Abstract] [Full Text] [Related] [New Search]