Chamazulene-rich artemisia arborescens essential oils affect the cell growth of human melanoma cells

Artemisia arborescens is an aromatic shrub whose essential oils are considered a potential source of molecules with industrial and pharmaceutical interest. The chemical profile of A. arborescens essential oils (EOs) was shown to be quite variable and various chemotypes have been identified. In this study, we compared the EOs composition of A. arborescens leaves and flowers collected from four different locations in Sicily. The EOs were assayed for their antiproliferative activity against A375 human malignant melanoma cells, also testing cell viability and cell membrane integrity. The evaluation of DNA fragmentation and caspase-3 activity assay was employed for the detection of apoptosis. The expression of Bcl-2, Bax, cleaved caspase-9, PTEN (Phosphatase and tensin homolog), Hsp70 (Heat Shock Protein 70 kilodaltons) and SOD (superoxide dismutase) proteins was evaluated by Western blot analysis. The levels of ROS and GSH were also analyzed. Results show that EOs presented significant differences in their composition, yield, and cytotoxic activity depending on the collection site. The chamazulene/camphor-rich EOs from plants collected in Acqua Calda (Lipari) resulted particularly active on melanoma cancer cells (IC50 values of 6.7 and 4.5 µg/mL), being able to trigger apoptotic death probably interfering with endogenous defense mechanisms. These oils may be considered as a natural resource of chamazulene, containing this compound up to 63%