title: Penetration and haptenation of p-phenylenediamine.
abstract: Although p-phenylenediamine (PPD) has been recognized as an extreme sensitizer for many years, the exact mechanism of sensitization has not been elucidated yet. Penetration and the ability to bind to proteins are the first two hurdles that an allergen has to overcome to be able to sensitize. This review is an overview of studies regarding PPD penetration through skin (analogues) and studies on the amino acids that are targeted by PPD. To complete this review, the auto-oxidation and N-acetylation steps involved in PPD metabolism are described. In summary, under normal hair dyeing exposure conditions, <1% of the applied PPD dose penetrates the skin. The majority (>80%) of PPD that penetrates will be converted into the detoxification products monoacetyl-PPD and diacetyl-PPD by the N-acetyltransferase enzymes. The small amount of PPD that does not become N-acetylated is susceptible to auto-oxidation reactions, yielding protein-reactive PPD derivatives. These derivatives may bind to specific amino acids, and some of the formed adducts might be the complexes responsible for sensitization. However, true in vivo evidence is lacking, and further research to unravel the definite mechanism of sensitization is needed.
authors.affiliation: Department of Dermatology, University Medical Centre Groningen, University of Groningen, 9700 RB Groningen, The Netherlands.
authors.forename: Laura M
authors.initials: LM
authors.lastname: Pot
authors.forename: Simone M
authors.initials: SM
authors.lastname: Scheitza
authors.forename: Pieter-Jan
authors.initials: PJ
authors.lastname: Coenraads
authors.forename: Brunhilde
authors.initials: B
authors.lastname: Blömeke
mesh_terms: D000107:Acetylation / Q000187:drug effects; D000287:Administration, Topical; D000818:Animals; D004396:Coloring Agents / Q000494:pharmacology*; D017449:Dermatitis, Allergic Contact / Q000209:etiology* / Q000503:physiopathology; D006202:Hair Dyes / Q000009:adverse effects / Q000378:metabolism*; D006801:Humans; D010655:Phenylenediamines / Q000009:adverse effects / Q000494:pharmacology*; D012869:Skin Absorption / Q000187:drug effects
chemical_list: D004396:Coloring Agents; D006202:Hair Dyes; D010655:Phenylenediamines; C029728:4-phenylenediamine