Avaliação da composição química e atividades biológicas do óleo essencial de Laurus nobilis l. (Lauraceae)

Abstract

The Laurus nobilis L. is a tree belonging to the family Lauraceae, native to Asia and cultivated in the South and Southeast of Brazil as an ornamental plant, popularly known as laurel. The essential oil was extracted by hydrodistillation in a Clevenger apparatus for 2 hours. The essential oil was fractionated in a chromatographic column to obtain the fractions. The essential oil and fractions were identified by GC/MS. Was mensured the content of phenolic compounds of essential oil and fractions, and antioxidant activity by the DPPH sequestration method, antimicrobial activity against the strains: Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 13883 and ATCC 70603, Proteus mirabilis ATCC 7002, Pseudomonas aeruginosa 27853 and Staphylococcus aureus ATCC 25923, yeasts Candida albicans ATCC 18804, Candida krusei ATCC 20298, Candida parapsilosis ATCC 20019, Candida tropicalis ATCC 750, Cryptococcus gattii L21 / 01 and Cryptococcus neoformans H99, and the filamentous fungi Aspergillus niger IC (clinical isolate), Aspergillus flavus IMI 190443, Aspergillus fumigatus ATCC 16913 by the diffusion test on agar. The minimal inhibitory concentration (MIC) of the sensitive strains was determined by the broth dilution method. And the acaricidal activity against Rhipicephalus microplus by the test of immersion of females and larval, the larvicidal activity against Aedes aegypti by the test of larval immersion. Twenty compounds were identified in the essential oil with 99.01% of the identified peak areas. The major component of the essential oil was the 1.8-cineole with 34.01%. The essential oil of laurel presented 17.57 μg of gallic acid / mg of essential oil of phenolic compounds and showed antioxidant activity by the DPPH method with IC50 of 15.52 mg/mL and the fractions CH2Cl2:C6H14 (8: 2) 9, 96 mg/mL and CH2Cl2: C6H14 (7: 3) 3.65 mg/mL. The essential oil and the CH2Cl2: AcOEt (9:1) fraction showed antibacterial activity against the bacteria Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis and antifungal activity against strains of Candida albicans, C. krusei, C. parapsilosis, C. tropicalis and Cryptococcus gattii and C. neoformans with minimum inhibitory concentration (MIC) values between 10.00 and 0.31 mg/mL. In relation to the acaricide activity, the immersion test of engorged females of R. microplus had a decrease in egg mass, egg production index and egg viability were affected in the different concentrations of essential oil in relation to the control group. On the larvae of the tick, the essential oil presented LC50 of 3.52 μL/mL and LC99 of 5.94 μL/mL, among the fractions to CH2Cl2: AcOEt (8:2) was the most active with LC50 of 0.13 μL/mL and LC99 of 0.51 μL/mL and the essential oil presented on larvae of A. aegypti LC50 of 0.38 μL/mL and LC99 of 0.48 μL/mL. Therefore, it can be concluded that the essential oil has antioxidant, antimicrobial, acaricidal and larvicidal action on R. microplus and A. aegypti, and that the fractionation was of great importance for the identification of compounds with biological activity.