Análise do efeito da fase vapor do óleo essencial de patchouli na proliferação celular de linhagens de carcinoma de pulmão

Abstract

Among cancers, lung cancer is one of the most resistant to traditional treatments, which highlights the need for the development of new therapeutic strategies. In this context, essential oils (EOs) have emerged as a promising complementary treatment option, as they are compounds made up of volatile molecules with several pharmacological properties that can be delivered directly to lung tissue via inhalation pathway. The aim of this study was to evaluate the effect of the vapor phase (VP) of commercial patchouli EO on the viability and proliferation of human lung adenocarcinoma cells (A549), human lung mucoepidermoid carcinoma cells (H292), and human lung fibroblasts (MRC-5). As an experimental strategy, the cells were plated in the eight central wells of the 24-well culture plates and treated for 72 hours with the EO vapor at different concentrations (0-1000 μg/mL/well), which was added to the remaining 16 cell-free wells. Cytotoxicity was determined using the MTT reduction and sulforhodamine B (SRB) staining assays, from which the concentration of EO capable of generating enough vapor to reduce cell viability by 50% (ICV50) and the selectivity index (SI), calculated by the ratio of the ICV50 of the non-tumor cell line (MRC-5) to the ICV50 of the tumor cell lines (A549 and H292), were calculated. The ICV50 was also used to carry out time-response assays. Furthermore, the effect of the VP of patchouli EO on the A549 cell line was also assessed in terms of cell migration capacity and cell distribution in different phases of the cell cycle, using the scratch assay and flow cytometry using propidium iodide (PI), respectively. The VP of the EO reduced cell viability for both tumor cell lines, however, the A549 cell line was more sensitive to the treatment, with an ICV50 value obtained for the MTT reduction assay of 169.74 μg/mL and 156.13 μg/mL for the SRB assay. For the H292 cell line, the calculated values were 215 and 220.74 μg/mL for the MTT and SRB assays, respectively. For the control cell line (MRC-5), the EO exhibited a cytotoxic effect with an ICV50 of 333.75 μg/mL (MTT) and 316.30 μg/mL (SRB), however, the SI value was less than 2, indicating that the VP of the EO was not selective. The results of the scratch assay suggest that patchouli EO significantly reduces migration in the A549 cell line. The VP of patchouli EO decreased cell proliferation at a concentration of 170 μg/mL in a time-dependent manner and induced cell cycle arrest in A549 cells by increasing the percentage of cells in the G0/G1 and decreasing the percentage of cells in the S and G2/M phases. In conclusion, these findings indicate that the VP of patchouli EO reduces the cell proliferation of lung cancer tumor cell lines. However, futures studies still need be to carried out to elucidate the mechanisms involved.