Seseli tortuosum L. subsp. tortuosum Essential Oils and Their Principal Constituents as Anticancer Agents

Seseli tortuosum L. subsp. tortuosum, belonging to the Apiaceae family, is a species that grows in Europe, mainly in the Mediterranean regions. The history of its application in traditional medicine highlights its various biological properties. Trying to explore the phytochemistry and pharmacological aspects of this species, the essential oils (EOs) extracted from flowers, stems, and roots of a locally wild accession, never previously investigated, growing in Sicily, Italy, were investigated. The chemical composition of all EOs, obtained by the hydrodistillation method, was evaluated by GC-MS. The most abundant class of all investigated samples was that of monoterpene hydrocarbons (79.98-91.21%) with p-cymene, alpha-pinene, beta-pinene, and beta-ocimene as major compounds. These EOs, and their main components, were tested for their possible anticancer activity. Obtained data provided evidence that among the different EOs tested, at the dose of 100 mu g/mL, those extracted from stems and roots were particularly effective, already at 24 h of treatment, in reducing the cell viability of 42% and 95%, respectively, in HCT116 colon cancer cell line. These EOs also exerted a remarkable cytotoxic effect that was accompanied by morphological changes represented by cell shrinkage as well as a reduction in residual cell population. Differently, modest effects were found when EOs extracted from flowers were tested in the same experimental conditions. The evaluation of the phytocompounds mainly represented in the EOs extracted from different parts of the plant and tested in a range of concentrations between 20 and 200 mu g/mL, revealed that alpha-pinene, beta-pinene, and p-cymene exerted only modest effects on cell viability. Differently, a remarkable effect was found when beta-ocimene, the most abundant phytocomponent in EOs from roots, was tested on colon cancer cells. This phytocompound, among those identified in EOs from Seseli tortuosum L. subsp. tortuosum, was found to be the most effective in reducing colon cancer cell viability with IC50 = 64.52 mu g/mL at 24 h of treatment. All together, these data suggest that beta-ocimene could be responsible for the effects observed in colon cancer cells.