Composition and antimicrobial activity of the essential oils from invasive species of the Azores, Hedychium gardnerianum and Pittosporum undulatum.

The compositions of the essential oils from the leaves and flowers of Hedychium gardnerianum and from the leaves of Pittosporum undulatum growing on San Miguel Island (Azores) were investigated, and the compounds were identified by GC-MS analyses. The oils in the leaves and flowers of H. gardnerianum were rich in alpha-pinene, beta-pinene and alpha-cadinol, whereas that from P. undulatum was found to contain monoterpenes, sesquiterpenes, diterpenes and alkanes, of which the sesquiterpenes, calamenene (41.4%), farnesol (10.9%), spathulenol (5.6%) and beta-selinene (5.2%) and the diterpene (8beta,13beta)-kaur-16-ene (10.7%) were the major components. Their potential antimicrobial activities were tested against Staphylococcus aureus, S. epidermis and Pseudomonas aeruginosa, and those with the highest activities against S. aureus and S. epidermis were from H. gardnerianum; none had activity against P. aeruginosa. Additionally, the essential oils from Pittosporum undulatum had good antithrombin activity whereas that from H. gardnerianum did not.