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

The major terpenoid components of the essential oils of the invasive plant species, Hedychium gardnerianumn leaf and floral tissues and Pittosporum undulatum leaf tissues were identified. Essential oils from H. gardnerianumn were active against Staphylococcus aureus, S. epidermis, whereas P. undulatum oils had antithrombin activity. 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 α-pinene, β-pinene and α-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 β-selinene (5.2%) and the diterpene (8β,13β)-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.