Chemical composition and in vitro antimicrobial, antifungal and antioxidant properties of essential oils obtained from some herbs widely used in Portugal

Abstract

The aim of this study was determine (i) the chemical composition (ii) the antimicrobial activity (antibacterial and antifungal) and (iii) the antioxidant activity by means of four different antioxidant tests (DDPH, FIC, FRAP and TBARS) of the EOs of three aromatic herbs, Coriander (Coriandrum sativum), celery (Apium graveolens) and bush-basil (Ocimum minimum) widely used in Portugal.There is a great variability of the compounds presented in the three tested essential oils. Bush-basil EO had the highest total phenolic content (794.9 mg GAE/L) while coriander EO had the lower total phenolic content (52.3 mg GAE/L). Since bush-basil had the highest TPC it was expected to present a very high antioxidant profile, which was verified in 3 of the 4 assays (DPPH inhibition of 95.9%; FRAP values of 2.7 mmol Trolox/L; TBARS inhibition of 87.2%); coriander, despite the low TPC showed the highest inhibition in the FIC assay (94.1%).The bush-basil EO showed the highest antimicrobial activity, with MIC ranging between 0.6 and 5 μL/mL against bacteria and 0.04–2.5 μL/mL against yeasts. Both celery and coriander EO had a very similar antimicrobial activity against all the tested strains. The antifungal activity was higher in the bush-basil EO against Mucor racemosus and Penicillium chrysogenum since it was the only EO that showed growth inhibition on all the tested concentrations. Alternaria alternata showed great resistance against all the tested essential oils.