title: Cinnamyl alcohol oxidizes rapidly upon air exposure.
abstract: BACKGROUND
  Cinnamyl alcohol and cinnamal are frequent fragrance contact allergens. Both are included in the European baseline fragrance mix I, which is used for screening of contact allergy in dermatitis patients.
  
  
  OBJECTIVE
  The aim of this study was to investigate the autoxidation of cinnamyl alcohol and to identify the oxidation products formed on air exposure. We also wanted to evaluate the effect of autoxidation on the sensitization potency of cinnamyl alcohol.
  
  
  METHODS
  Samples of commercially available cinnamyl alcohol with and without purification were exposed to air, and the autoxidation was followed by chemical analysis. The analysis was performed with mass spectrometry (LC/MS/MS). Sensitization potencies of compounds were determined with the murine local lymph node assay (LLNA) in mice.
  
  
  RESULTS
  Chemical analysis showed that the concentration of cinnamyl alcohol in the air-exposed samples decreased rapidly over time, and that autoxidation products were formed. Cinnamal, epoxy cinnamyl alcohol and cinnamic acid were identified as oxidation products. According to our study, cinnamal and epoxy cinnamyl alcohol were the first autoxidation products formed. The epoxy cinnamyl alcohol was shown to be the oxidation product with the highest sensitization potency. The analysis of our samples of commercially available cinnamyl alcohol showed that there was already a content of 1.5% cinnamal at the start of the autoxidation experiments.
  
  
  CONCLUSIONS
  Cinnamyl alcohol readily autoxidizes upon air exposure, and forms strong sensitizers as determined by the LLNA. Cinnamal was formed in the largest amounts, showing that cinnamal is not only formed via bioactivation, as has previously been shown. A highly sensitizing epoxide was also identified and quantified in the oxidation mixture.
authors: Department of Chemistry and Molecular Biology, Dermatochemistry and Skin Allergy, University of Gothenburg, SE-412 96 Gothenburg, Sweden.
authors: Ida B
authors: IB
authors: Niklasson
authors: Tamara
authors: T
authors: Delaine
authors: M Nurul
authors: MN
authors: Islam
authors: Roger
authors: R
authors: Karlsson
authors: Kristina
authors: K
authors: Luthman
authors: Ann-Therese
authors: AT
authors: Karlberg
mesh_terms: D000171:Acrolein / Q000031:analogs & derivatives / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D000388:Air; D000485:Allergens / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D002934:Cinnamates / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D004852:Epoxy Compounds / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D023441:Local Lymph Node Assay; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D010084:Oxidation-Reduction; D020005:Propanols / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism
chemical_list: D000485:Allergens; D002934:Cinnamates; D004852:Epoxy Compounds; D020005:Propanols; C029010:cinnamic acid; D000171:Acrolein; C012843:cinnamaldehyde; C020722:cinnamyl alcohol