Bioactivities of Volatile Components from Nepalese ArtemisiaSpecies

The essential oils from the leaves of Artemisia dubia, A. indica, and A. vulgarisgrowing wild in Nepal were obtained by hydrodistillation and analyzed by GC-MS. The major components in A. dubiaoil were chrysanthenone (29.0%), coumarin (18.3%), and camphor (16.4%). A. indicaoil was dominated by ascaridole (15.4%), isoascaridole (9.9%), trans-p-mentha-2,8-dien-1-ol(9.7%), and trans-verbenol (8.4%). The essential oil of Nepalese A. vulgariswas rich in α-thujone (30.5%), 1,8-cineole (12.4%), and camphor (10.3%). The essential oils were screened for phytotoxic activity against Lactuca sativa(lettuce) and Lolium perenne(perennial ryegrass) using both seed germination and seedling growth, and all three Artemisiaoils exhibited notable allelopathic activity. A. dubiaoil showed in-vitrocytotoxic activity on MCF-7 cells (100% kill at 100 μg/mL) and was also marginally antifungal against Aspergillus niger(MIC = 313 μg/mL). DFT calculations (B3LYP/6-31G*) revealed thermal decomposition of ascaridole to be energetically accessible at hydrodistillation and GC conditions, but these are spin-forbidden processes. If decomposition does occur, it likely proceeds by way of homolytic peroxide bond cleavage rather than retro-Diels-Alder elimination of molecular oxygen.