Chemical Composition, Antibacterial Activity using Micro-broth Dilution Method and Antioxidant Activity of Essential Oil and Water Extract from Aerial Part of Tunisian Thymus algeriensis Boiss. & Reut.

Abstract

In this study, we investigated the chemical composition, antioxidant and antibacterial activities of essential oil and aqueous extract from Thymus algeriensis Boiss. & Reut growing in Tunisia. GC/MS analysis of essential oil from the aerial part of the plant led to identifying 54 constituents representing 96.87 % of the total oil composition. Monoterpenes represented the major components of the essential oil. On the other hand, the aqueous extract and the essential oil were screened for their antioxidant and antibacterial activities. The latter was assessed against Gram-negative and Gram-positive bacterial strains using the broth dilution micro method for the determination of antibacterial activity. The antioxidant activity was evaluated using the DPPH scavenging activity and Ferric Reducing/Antioxidant Power (FRAP) assays. The essential oil was found to be more active in antibacterial screening (MIC = 0.54 μg/mL). Whereas the aqueous extract exhibited the most potent antioxidant activity with (IC50 = 0.04 μg/mL). UHPLC ESI(-)-HRMS/MS analysis of the aqueous extract allowed tentative identification of its constituents and showed that it is rich in phenolic compounds. Luteolin-glucuronide was found to be the most abundant compound followed by Vicenin-2 and Apigenin-diglucuronide.