Browsing by Author "Bounatirou, S."
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- Chemical composition, antioxidant and antibacterial activities of the essential oils isolated from Tunisian Thymus capitatus Hoff. et Link.Publication . Bounatirou, S.; Smiti, S.; Miguel, Maria Graça; Faleiro, Leonor; Rejeb, M. N.; Neffati, M.; Costa, M. M.; Figueiredo, A. C.; Barroso, J. G.; Pedro, L. G.The chemical composition, antioxidant and antibacterial activities of essential oils isolated by hydrodistillation from the aerial parts of Tunisian Thymus capitatus Hoff. et Link. during the different phases of the plant development, and from different locations, were evaluated. The chemical composition was analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The main components of the essential oils were carvacrol (62-83%), p-cymene (5-17%), gamma-terpinene (2-14%) and P-caryophyllene (1-4%). The antioxidant activity of the oils (100-1000 mg l(-1)) was assessed by measurement of metal chelating activity, the reductive potential, the free radical scavenging (DPPH) and by the TBARS assay. The antioxidant activity was compared with that of synthetic antioxidants: butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). Both the essential oils and BHA and BHT showed no metal chelating activity. Although with the other methodologies, there was a general increase in the antioxidant activity, with increasing oil concentration, maxima being obtained in the range of 500 and 1000 mg l(-1) for flowering and post-flowering phase oils. Major differences were obtained according to the methodology of antioxidant capacity evaluation. Antibacterial ability of Th. capitatus essential oils was tested by disc agar diffusion against Bacillus cereus, Salmonella sp., Listeria innocua, four different strains of Staphylococus aureus (Cl 5, ATCC25923, CFSA-2) and a multi-resistant form of S. aureus (MRSA-2). Antibacterial properties were compared to synthetic antibiotics. Higher antibacterial activity was observed with the flowering and the post-flowering phase essential oils. (c) 2007 Elsevier Ltd. All rights reserved.
- Thermal stability of the essential oils isolated from Tunisian Thymus capitatus Hoff. et Link.: Effect on the chemical composition and the antioxidant and antibacterial activitiesPublication . Bounatirou, S.; Smiti, S.; Miguel, Maria Graça; Faleiro, Leonor; Rejeb, M. N.; Neffati, M.; Costa, M. M.; Figueiredo, A. C.; Barroso, J. G.; Pedro, LgThe chemical composition, the antioxidant and the antibacterial activities of essential oils, isolated from the aerial parts of Tunisian Thymus capitatus during the flowering phase, and stored in the dark during 37 days in the oven, at 60 degrees C were evaluated. Samples taken periodically were used to evaluate the chemical composition, the antioxidant and the antibacterial activities. With some fluctuations, carvacrol (68-74%) was the major component of the oil independent of the storage period. alpha-Terpinene and gamma-terpinene decreased over time, whereas p-cymene increased in the same period. Despite the thirty-seven days of storage at 60 degrees C, T. capitatus essential oil still showed high antioxidant and stable antimicrobial activity.