Antibacterial activity evaluation of Tunisian Thymus capitatus essential oils

S. Bounatirou; S. Smiti; M. N. Rejeb; M. Neffati; M. M. Costa; M. L. Faleiro; M. G. Miguel; A. C. Figueiredo; J. G. Barroso; L. G. Pedro

doi:10.1055/s-2006-950010

Antibacterial activity evaluation of Tunisian Thymus capitatus essential oils

S Bounatirou ¹, S Smiti ¹, MN Rejeb ², M Neffati ³, MM Costa ⁴, ML Faleiro ⁵, MG Miguel ⁵, AC Figueiredo ⁴, JG Barroso ⁴, LG Pedro ⁴

¹Faculté des Sciences de Tunis, Université Tunis el Manar, Campus Universitaire, 2092 Tunis, Tunisia
²Institut National de Recherche en Génie Rural, Eaux et Forêts, 2080 Tunis, Tunisia
³Institut des Régions Arides, 4119 Mednine, Tunisia
⁴Universidade de Lisboa, Faculdade de Ciências de Lisboa, DBV, Centro de Biotecnologia Vegetal, C2, Campo Grande, 1749–016Lisbon, Portugal
⁵Faculdade de Engenharia de Recursos Naturais, Universidade do Algarve, Campus de Gambelas, 8005–139 Faro, Portugal

Abstract

Thymus capitatus L. (Hoffm.) commonly used in Tunisia for culinary purposes and locally known as “zaâtar“ is a perennial, herbaceous shrub (Lamiaceae).

Th. capitatus essential oils were isolated by hydrodistillation from the aerial parts of plants collected during the different phases of the plant development at different locations (Jendouba, Aîn Tounine and Haouaria) in a total of 16 oils. The main components of the essential oils were carvacrol (62–83%), p-cymene (5–17%) and γ-terpinene (2–14%).

In this work, we evaluated using the disc agar diffusion technique the antibacterial ability of all Th. capitatus essential oils against:

1) Bacillus cereus (C1060), Salmonella sp. and Listeria innocua [0.8µL/disc]

2) Three different strains of Staphylococus aureus (C15, ATCC 6538 and ATCC 25923) [0.4µL/disc]

The most effective oils (8) were assayed against:

3) S. aureus C15, CFSA-2 and ATCC 25923 and one multi-resistant form of S. aureus (MRSA-2) [0.8µL/disc].

Listeria innocua was the most susceptible of the three tested bacteria in assay (1). Of the 16 oils assayed, the flower buds and flower oils from Jendouba had a similar effect to that of the antibiotic. Of the three Staphylococus strains studied in assay (2), ATCC 6538 was more susceptible than C15 and ATCC25923. Of the 16 oils, 12 were the most effective, all from the flowering and the fructification phases, showing a diameter of inhibition zone 1.3 times higher than that of the antibiotic. Multi-resistant form of S. aureus studied in assay (3) was most vulnerable to TC11 (Jendouba, flowering buds oil). Th. capitatus essential oils seem to constitute an effective biocide to either combat foodborne pathogens or serious clinical pathogens such as MRSA.