Avaliação da atividade larvicida do extrato bruto etanólico e óleos essenciais das folhas de origanum majorana L. e origanum vulgare L. frente ao Aedes aeggypti (Linnaeus, 1762)

Abstract

Introduction: Origanum majorana L. and Origanum vulgare L. belong to the family Lamiaceae and are popularly known as manjorana and oregano, respectively. Objective: To evaluate the larvicidal activity of O. majorana L. and O. vulgare L. against Aedes aegypti. Methodology: the larvicidal bioassay was performed with larvae in the third stage of A. aegypti; the identifications of the components of the oils by Gas Chromatography Coupled to the Mass Spectrophotometer; the crude ethanolic extract by phytochemical evaluation; the microbiological activity by the microdilution method with bacteria Pseudomona aeruginosa, Escherichia coli and Staphylococcus aureus; the antioxidant was evaluated by the sequestration method of the 2.2-diphenyl-1-picryl-hydrazyl radical and the cytotoxic activity was performed using Artemia saline. Results and discussion: Manjerona and oregano oils presented high larvicidal activity with LC50 of 74.63 and 56.00 μg.mL-1 after 24h, LC50 of 20.27 and 15.69 μg.mL-1 respectively, after 48h. Manjerona extract showed good activity with LC50 of 219.14 and 79.40 μg.mL-1 after 24h and 48h, respectively. The major constituents found in the manjerona and oregano oils were pulegone (57.05%), γ-terpinene (27.18%), respectively. In the extract were found reducing sugars, tannins, phenols, depsides and depsedones, steroids and triterpenoids. P. aeruginosa and E. coli were more susceptible in oils and extract with MIC of 31.25 μg.mL-1. Only the oil of oregano opposite S. aureus with MIC of 500 μg.mL-1. In the MBM of oregano oil, concentrations of 250, 500 and 1000 μg.mL-1 inhibited the growth of P. aeruginosa, S. aureus and E. coli, respectively. In manjerona oil the concentrations of 1000 and 500 μg.mL-1 inhibited the growth of P. aeruginosa and E. coli. There was no antioxidant activity of the plants, but there was cytotoxic activity of oregano and manjerona oils at A. salina with high LC50 of 38.11 and 172.6 μg.mL-1 and low LC50 of 946.9 μg.mL-1 extract. Conclusions: In this way, the oils and extract obtained from the leaves of O. vulgare L. and O. majorana L. present potential for the development of natural larvicides