MECHANISTIC ASPECTS OF THE BIOGENESIS OF ROSE OXIDE IN PELARGONIUM GRAVEOLENS LHERITIER

Mechanistic aspects of the biogenesis of the chiral monoterpenoid rose oxide in Pelargonium graveolens L'Heritier are investigated using deu terium-labelled precursors. After administration of the precursors usi ng the cut-stem method, the dynamic headspace extracts of the plants a re analysed using multidimensional gas chromatography-mass spectrometr y (enantio-MDGC-MS). It is unequivocally shown that this plant is able to convert citronellol and menthocitronellol into cis-/trans-rose oxi de. Menthocitronellol is converted into rose oxide with a clearly dete ctable enantiodiscrimination. These facts may be explained with the pr esence of an oxidase, which is able to oxidize citronellol and menthoc itronellol in allylic position. A photooxygenation mechanism including singlet oxygen as the oxidizing agent is rather unlikely. (C) 1998 Wi ley-Liss, Inc.