Mortality data were evaluated by linear regression to determine the LC 50 . Was obtained 0.5% yield values, and (E) -caryophyllene the major constituent. The essential oil showed a LC 50 = 79.44 mg / mL front A. saline and is considered highly toxic. However, this oil showed no effect on larvae of A. aegypti. Whereas the brine shrimp test has regard to several biological activities, as antitumoral property, the essential oil from the leaves of M. sylvatica demonstrated potential for development of medicines.

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Ocimum gratissimum oil is used for various medicinal, food and cosmetic applications due to its high chemical variability. Local businesses have considered the economic exploitation of this plant. A specimen sampled at São Luís, MA, Brazil, with thymol and derivatives oil, was subjected to seasonal and circadian study, and to antifungal and antioxidant assays. It was possible to observe that the weather conditions showed a direct influence on the oil yield and variation of its constituents, mainly oxygenated monoterpenes and monoterpene hydrocarbons, with the predominance of thymol, γ-terpinene, and p-cymene. Principal component analysis (PCA) was able to justify the oil chemical variability of the seasonal (70%) and circadian (86%) study. Oil displayed inhibition for the fungus Corynespora cassiicola at a concentration above 0.3 µL mL-1 , and it showed a more significant activity by comparison to thymol. Using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical assay, the oil antioxidant activity was about 75% of thymol.

Essential oils (EOs) of the leaves of three Eugenia punicifolia specimens from two different Reservation Parks, namely Parque Nacional das Nascentes do Rio Parnaíba (EpNRP-I and EpNRP-II) and Parque Nacional da Chapada das Mesas (EpCM), in the state of Maranhão, Brazil, were extracted by hydrodistillation and investigated by gas chromatography coupled to mass spectrometry. Principal component and hierarchical cluster analyses indicated differences between the samples. Antiproliferative EOs activity was determined for U-251 (glioblastoma), MCF-7 (breast adenocarcinoma), NCI/ADR-RES (multidrug-resistant ovarian adenocarcinoma), OVCAR-3 (ovarian adenocarcinoma), HT-29 (colorectal adenocarcinoma), and HaCaT (non‑tumor keratinocyte) cell lines applying the colorimetric method using 3-(4,5-dimethyl- 2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) to determine the GI50 (50% growth inhibition) concentration. The extraction yields of the analyzed EOs were 0.58, 1.42 and 0.84%. The main constituents identified in two samples were α-pinene (49.75%), 1,8-cineole (13.77%) and α-terpineol (7.32%), and in the third sample, germacrene B (16.25%), (E)-caryophyllene (13.21%) and β-pinene (12.81%). The main GI50 results for sample EpNRP-I were noted for the U-251 (2.13 μg mL−1) and MCF-7 (6.72 μg mL−1) tumor lines. For the non-tumoral line HaCaT, the calculated GI50 was higher than the positive control comprising doxorubicin hydrochloride (13.35 μg mL−1). In addition, a flow cytometry analysis revealed that this same sample arrests the cell cycle of the MCF-7 line in the second interphase stage.

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