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Title: Skin metabolism of aminophenols: Human keratinocytes as a suitable in vitro model to qualitatively predict the dermal transformation of 4-amino-2-hydroxytoluene in vivo

Abstract

4-Amino-2-hydroxytolune (AHT) is an aromatic amine ingredient in oxidative hair colouring products. As skin contact occurs during hair dyeing, characterisation of dermal metabolism is important for the safety assessment of this chemical class. We have compared the metabolism of AHT in the human keratinocyte cell line HaCaT with that observed ex-vivo in human skin and in vivo (topical application versus oral (p.o.) and intravenous (i.v.) route). Three major metabolites of AHT were excreted, i.e. N-acetyl-AHT, AHT-sulfate and AHT-glucuronide. When 12.5 mg/kg AHT was applied topically, the relative amounts of each metabolite were altered such that N-acetyl-AHT product was the major metabolite (66% of the dose in comparison with 37% and 32% of the same applied dose after i.v. and p.o. administration, respectively). N-acetylated products were the only metabolites detected in HaCaT cells and ex-vivo whole human skin discs for AHT and p-aminophenol (PAP), an aromatic amine known to undergo N-acetylation in vivo. Since N-acetyltransferase 1 (NAT1) is the responsible enzyme, kinetics of AHT was further compared to the standard NAT1 substrate p-aminobenzoic acid (PABA) in the HaCaT model revealing similar values for K{sub m} and V{sub max}. In conclusion NAT1 dependent dermal N-acetylation of AHT represents a 'first-pass' metabolism effectmore » in the skin prior to entering the systemic circulation. Since the HaCaT cell model represents a suitable in vitro assay for addressing the qualitative contribution of the skin to the metabolism of topically-applied aromatic amines it may contribute to a reduction in animal testing.« less

Authors:
 [1];  [2];  [3];  [4];  [5];  [3];  [6]
  1. Procter and Gamble Service GmbH, Central Product Safety, Darmstadt Innovation Center, Berliner Allee 65, 64274 Darmstadt (Germany), E-mail: goebel.c.1@pg.com
  2. Wingertstrasse 25, 64390 Erzhausen (Germany)
  3. Procter and Gamble Co., Central Product Safety, Cosmital SA, Marly (Switzerland)
  4. NOTOX B.V., Hambakenwetering 7, 5231 DD 's-Hertogenbosch (Netherlands)
  5. Department of Pharmacology and Toxicology, University of Louisville School of Medicine, 40292 Kentucky (United States)
  6. Procter and Gamble Co., Central Product Safety, Sharon Woods Technical Center, Cincinnati, OH 45241 (United States)
Publication Date:
OSTI Identifier:
21182738
Resource Type:
Journal Article
Resource Relation:
Journal Name: Toxicology and Applied Pharmacology; Journal Volume: 235; Journal Issue: 1; Other Information: DOI: 10.1016/j.taap.2008.11.014; PII: S0041-008X(08)00488-2; Copyright (c) 2009 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; ACETYLATION; AMINES; ENZYMES; HAIR; IN VITRO; IN VIVO; METABOLISM; METABOLITES; OXIDATION; PABA; RISK ASSESSMENT; TRANSFORMATIONS

Citation Formats

Goebel, C., Hewitt, N.J., Kunze, G., Wenker, M., Hein, D.W., Beck, H., and Skare, J. Skin metabolism of aminophenols: Human keratinocytes as a suitable in vitro model to qualitatively predict the dermal transformation of 4-amino-2-hydroxytoluene in vivo. United States: N. p., 2009. Web. doi:10.1016/j.taap.2008.11.014.
Goebel, C., Hewitt, N.J., Kunze, G., Wenker, M., Hein, D.W., Beck, H., & Skare, J. Skin metabolism of aminophenols: Human keratinocytes as a suitable in vitro model to qualitatively predict the dermal transformation of 4-amino-2-hydroxytoluene in vivo. United States. doi:10.1016/j.taap.2008.11.014.
Goebel, C., Hewitt, N.J., Kunze, G., Wenker, M., Hein, D.W., Beck, H., and Skare, J. 2009. "Skin metabolism of aminophenols: Human keratinocytes as a suitable in vitro model to qualitatively predict the dermal transformation of 4-amino-2-hydroxytoluene in vivo". United States. doi:10.1016/j.taap.2008.11.014.
@article{osti_21182738,
title = {Skin metabolism of aminophenols: Human keratinocytes as a suitable in vitro model to qualitatively predict the dermal transformation of 4-amino-2-hydroxytoluene in vivo},
author = {Goebel, C. and Hewitt, N.J. and Kunze, G. and Wenker, M. and Hein, D.W. and Beck, H. and Skare, J.},
abstractNote = {4-Amino-2-hydroxytolune (AHT) is an aromatic amine ingredient in oxidative hair colouring products. As skin contact occurs during hair dyeing, characterisation of dermal metabolism is important for the safety assessment of this chemical class. We have compared the metabolism of AHT in the human keratinocyte cell line HaCaT with that observed ex-vivo in human skin and in vivo (topical application versus oral (p.o.) and intravenous (i.v.) route). Three major metabolites of AHT were excreted, i.e. N-acetyl-AHT, AHT-sulfate and AHT-glucuronide. When 12.5 mg/kg AHT was applied topically, the relative amounts of each metabolite were altered such that N-acetyl-AHT product was the major metabolite (66% of the dose in comparison with 37% and 32% of the same applied dose after i.v. and p.o. administration, respectively). N-acetylated products were the only metabolites detected in HaCaT cells and ex-vivo whole human skin discs for AHT and p-aminophenol (PAP), an aromatic amine known to undergo N-acetylation in vivo. Since N-acetyltransferase 1 (NAT1) is the responsible enzyme, kinetics of AHT was further compared to the standard NAT1 substrate p-aminobenzoic acid (PABA) in the HaCaT model revealing similar values for K{sub m} and V{sub max}. In conclusion NAT1 dependent dermal N-acetylation of AHT represents a 'first-pass' metabolism effect in the skin prior to entering the systemic circulation. Since the HaCaT cell model represents a suitable in vitro assay for addressing the qualitative contribution of the skin to the metabolism of topically-applied aromatic amines it may contribute to a reduction in animal testing.},
doi = {10.1016/j.taap.2008.11.014},
journal = {Toxicology and Applied Pharmacology},
number = 1,
volume = 235,
place = {United States},
year = 2009,
month = 2
}
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