Acmella oleracea (L.) RK Jansen essential oils: Chemical composition, antioxidant, and cytotoxic activities

Acmella oleracea is an important food and medicinal plant in the Amazon; it is used to treat toothaches, hepatitis, malaria, fever is also described as an anticancer plant. This work reports for the first time the comparison of chemical profiles, antioxidant, and cytotoxic capacities of inflorescence (INF) and leaf (LEA) A. oleracea essential oils (EOs) obtained by hydrodistillation (HD) and steam distillation (SD). The essential oils were obtained by hydrodistillation and steam distillation and analyzed by GC and GC-MS. The antioxidant potential was evaluated by the co-oxidation method of the beta-carotene/linoleic acid, and the cytotoxic activity against healthy human embryonic kidney (HEK-293), gastric ascites (AGP-01), melanoma (SK-MEL-19), lung carcinoma (A549) malignant cell lines by the MTT method. The essential oils obtained from INF by HD and SD showed the highest yields (HD = 0.68; SD = 0.5%). The monoterpene hydrocarbons (0-49.97%) and sesquiterpene hydrocarbons (25.79-50.63%) were predominant in the analyzed oils. The main constituents (>10%) identified in the EO samples were caryophyllene oxide (0.3-28.11%), E-caryophyllene (6.71-27.31%), myrcene (0-25.03%), germacrene D (0.06-19.56%), guaiol (0-14.23%), 1-pentadecene (0-13.88%), and beta-pinene (0-10.04%). The chemometric analysis displayed the formation of three distinct groups of chemical compositions as follows: group I, LEA EOs (HD and SD); group II, INF EO (HD); and group III, INF EO (SD). The INF (14.3%) and LEA (9.0%) EOs showed antioxidant action with no significant difference (p < 0.05). The INF EO (HD) showed higher cytotoxicity against the malignant lineages of gastric ascites (IC50 5.31 mu g/mL), melanoma (IC50 6.43 mu g/mL), while the LEA EO (SD) was more cytotoxic against the lung carcinoma cell line (13.39 mu g/mL), and higher toxicity was also observed against the healthy embryonic kidney cell line (IC50 5.14 mu g/mL). Acmella oleracea is chemically influenced by the volatile extraction methods, and this influences on the antioxidant or cytotoxic capacity of the species.