title: Hydroperoxides in oxidized d-limonene identified as potent contact allergens.
abstract: Hydroperoxides of d-limonene were shown to be potent contact allergens when studied in guinea-pigs. Limonene-2-hydroperoxide (2-hydroperoxy-p-mentha-6,8-diene, a mixture of trans and cis isomers) was synthesized for the first time. The ratio between the trans and cis forms was 3:1. These two hydroperoxides were identified as the major hydroperoxides in autoxidized d-limonene. In photo-oxidized d-limonene, they constituted a minor part of the hydroperoxide fraction. Hydroperoxides may bind to proteins of the skin to make antigens either via a radical mechanism or after reactions to give epoxides. The cross-reactivity between the epoxide limonene-1,2-oxide, a potent contact allergen, and the hydroperoxides was therefore studied. No significant pattern of cross-reactivity was found. Further studies to identify and test the allergenicity of single hydroperoxides are needed to elucidate the mechanism of the allergenicity.
authors.affiliation: Department of Occupational Dermatology, National Institute of Occupational Health, Solna, Sweden.
authors.forename: A T
authors.initials: AT
authors.lastname: Karlberg
authors.forename: L P
authors.initials: LP
authors.lastname: Shao
authors.forename: U
authors.initials: U
authors.lastname: Nilsson
authors.forename: E
authors.initials: E
authors.lastname: Gäfvert
authors.forename: J L
authors.initials: JL
authors.lastname: Nilsson
mesh_terms: D000485:Allergens / Q000737:chemistry / Q000276:immunology*; D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry / Q000276:immunology*; D002384:Catalysis; D002849:Chromatography, Gas; D003429:Cross Reactions; D053138:Cyclohexenes; D003877:Dermatitis, Contact / Q000276:immunology*; D005260:Female; D006168:Guinea Pigs; D006861:Hydrogen Peroxide / Q000276:immunology; D007536:Isomerism; D000077222:Limonene; D009682:Magnetic Resonance Spectroscopy; D010777:Photochemistry; D013729:Terpenes / Q000138:chemical synthesis / Q000737:chemistry / Q000276:immunology*
chemical_list: D000485:Allergens; D000970:Antineoplastic Agents; D053138:Cyclohexenes; D013729:Terpenes; D000077222:Limonene; D006861:Hydrogen Peroxide