Antimicrobial and antioxidant bioautography activity of bark essential oil from ocotea quixos (lam.) kosterm

The present research evaluated the chemical composition as well as the antioxidant and antimicrobial properties of the essential oil from the bark of Ocotea quixos (Lam.) Kosterm. The major components of the essential oil were cinnamaldehyde <(E)-> (30.69%), methoxy cinnamaldehyde <(E)-o-> (16.29%), cinnamyl acetate <(E)-> (12.18%), and methyl cinnamate <(E)-> (5.72%). The antioxidant capacity showed to be superior to that of the essential oil of Tymus vulgaris. The results show low half maximal inhibitory concentration (IC50) values, which means that the essential oil has a high activity: 2,2-diphenyl-1-picrylhydrazyl (DPPH) IC50, 2.786 ± 0.150 mg mL-1; 2,2'-azino-di-(3-ethylbenzthiazoline sulfonic acid (ABTS) IC50, 0.240 ± 0.034 mg mL-1; and IC50 β-carotene test, 0.496 ± 0.017 mg mL-1. The essential oil was active with all the microorganisms evaluated, being very active against: Escherichia coli ATCC (American type culture collection) 25922, Staphylococcus aureus ATCC 29213, Listeria grayi ATCC 19120, Micrococcus luteus ATCC 4698, Trichophyton mentagrophytes ATCC 9533, and Trichophyton rubrum ATCC 13803. The bioautography assays showed that bergamoteno <α-trans-> and methoxy cinnamaldehyde <€-o-> were the responsible molecules for the antioxidant activity and cinnamyl acetate <€-> was the molecule responsible for the antimicrobial activity.