Supercritical CO2 extraction to obtain Lippia thymoides Mart. & Schauer (Verbenaceae) essential oil rich in thymol and evaluation of its antimicrobial activity

Abstract

In this paper, for the first time, the extraction of Lippia thymoides leaf essential oil (EO), by supercritical CO2, is reported. Extractions have been carried out at 40 and 50 °C, and 100, 200 and 300 bar. The mass yields from extraction, chemical composition, and antimicrobial activity were studied. The main constituent of essential oil samples was thymol (74.52 ± 11.24 %–88.56 ± 0.65 %). The highest mass yield was obtained at the 50 °C/300 bar isotherm (1.63 ± 0.01 %). The antimicrobial activity was evaluated in the oil obtained under condition of 50 °C and 200 bar, because this sample had a higher thymol percentage. Fungi C. albicans and C. tropicalis were sensitive to EO, presenting an inhibition halo of 10 and 8 mm, respectively, similar to those presented in thymol tests. EO also showed activity against S. aureus, however, was not active against E. coli.