Abstract
BACKGROUND: In patch testing, co-reactivity between Myroxylon pereirae resin, colophonium and propolis is well recognised. One of the possible explanations is that these materials have common allergenic ingredients. OBJECTIVES: To identify the main ingredients in M. pereirae resin and colophonium samples used in the preparation of commercial patch test allergens and to compare their compositions with each other as well as with propolis. MATERIALS AND METHODS: Analyses were performed on M. pereirae resin and colophonium samples using gas chromatography-mass spectrometry/flame ionisation detection of the volatile components obtained by headspace SPME (solid phase microextraction). RESULTS: The main ingredients in M. pereirae resin were benzyl benzoate, (E)-nerolidol, benzoic acid, benzyl alcohol, (E)-cinnamic acid, vanillin and (E)-benzyl cinnamate. In colophonium, longifolene, caryophyllene oxide, acetone + formic acid, α-terpineol and δ-cadinene + calamenene were the major constituents. CONCLUSIONS: The major ingredients of the volatile fractions of M. pereirae resin and colophonium are quite different; common haptens in volatile ingredients cannot readily explain co-reactivity. M. pereirae resin has cinnamic acid- and benzoic acid derivatives in common with propolis and in addition (E)-nerolidol and vanillin with Brazilian propolis and benzyl alcohol with Chinese propolis. Colophonium shares various ingredients with Brazilian propolis but few with the Chinese variety.