Potencial antineoplásico e avaliação da composição química dos óleos essenciais de folhas e flores de Tagetes ostenii Hicken

Abstract

Cervical cancer ranks fourth in incidence in women worldwide and the third in Brazil. Since conventional treatments have a series of adverse reactions, there is an urgency in the search for new strategies against cancer. In this context, natural products represent a promising source of new active molecules with antitumor potential. The Tagetes genus has been described in the scientific literature with numerous biological effects, but there are few data on the Tagetes ostenii Hicken species. In this work, we investigate the chemical composition of essential oils from leaves and flowers of T. ostenii and evaluated the effects of these oils in a cervical cancer cell line, SiHa, and non-tumoral cell line, HaCat. The chemical analysis revealed the major components of the leaves essential oil (EO 1) as dihydro-tagetone (65.3%) and (Z)-tagetone (14.9%), while (Z)-β-ocimene (56.3%), (Z)-ocimenone (26.8%) and (E)-ocimenone (11.8%) were the main compounds of the flower’s essential oil (EO 2), one week after extraction. The cell viability after treatment was evaluated by the MTT assay and revealed a significant inhibition in tumor cell viability at all concentrations for both tested oils. The IC50 of EO 1 in SiHa cells was 72 ng/mL and 83 ng/mL for EO 2. For HaCat cell line were observed an IC50 of 54.45 ng/mL for EO 1 and 20.83 ng/mL for EO 2. The combined treatment with EO 1 and cisplatin showed a synergistic effect after 48 and 72 hours of treatment, and after 24 and 48 hours for EO 2. Cell migration assessed through the Wound Healing assay revealed that the SiHa cells had their migration process reduced after 48 h of treatment with EO 2. Furthermore, both essential oils were able to significantly inhibit the adhesion process by increasing the number of viable cells in the supernatant about 2.8 times for EO 1 and 7.03 times for EO 2. Clonogenic ability was also reduced markedly by treatment with EO 1 and EO 2 after 24 h at 88.7% and 90%, respectively. Our results also suggest that EO 1 and EO 2 have long-lasting inhibitory activity in tumor cells because only 6,36% of the treated cells with EO 1 and 22,09% with EO 2 were able to recover the viability even after treatment withdrawal. Analysis using Flow cytometer with annexin V/propidium iodide demonstrated that both essential oils induced a cell death through late apoptosis in 4 most of the tumor cells after 24, 48 and 72 hours of treatment. Together these results suggest a promising antineoplastic effect of essential oils of T. ostenii and emphasize the importance and need for additional studies involving samples from plant species.