From biosynthesis in plants to post-biosynthetic enzymatic conversion. Generation of odor-impact rose oxides from citronellol-rich essential oils

International audience ; Citronellol is a monoterpene alcohol biosynthesized by various plant species belonging to different families of Angiosperm. Bioinspired by the metabolism of Rosa sp., able to produce (–)-cis-rose oxide from citronellol, we have studied and optimized a laccase-catalyzed oxidation of (±)-, (R)-, and (S)-citronellol into rose oxide diastereomers in the presence of mediators. The reaction was found to be diastereomerically cis-selective but completely non-enantioselective. The laccase-mediator system was then applied on citronellol-containing essential oils such as lemongrass (Cymbopogon citratus) and geranium (Pelargonium graveolens) essential oils in order to modify their composition beyond the plant metabolism and increase their rose oxides content, thereby tuning their olfactory properties.