Introduction

The objective of study was to compare the composition, antioxidative and  antibacterial activity (against food-borne pathogens) of essential oils of wild and cultivated thymus vulgaris (family: Lamiaceae).

The aerial parts of both cultivated and wild plants were collected in May 2011 from Shahrekord (Chaharmahal va Bakhtiari Province). The oils were obtained by hydro-distillation using a clevenger-type apparatus. Analyses of the oils were carried out using an Agilent HP-6890 gas chromatograph equipped with a flame ionization detector (FID) and a HP-5MS column (30 m × 0.25 mm, film thickness 0.25 μm). The GC/MS analyses were carried out using an Agilent HP-6890 gas chromatograph coupled with an Agilent HP-5973 mass spectrometer.

Antibacterial activity assessment was performed according to Saei-Dehkordi et al. [4] and NCCLS [5]. The test microorganisms were: Staphylococcus aureus ATCC 25923, Bacillus cereus ATCC 11778, Escherichia coli O157:H7 ATCC 25922 and Pseudomonas aeruginosa ATCC 27853. Also, amikacin was used as a standard antibacterial agent. DPPH assay and β-carotene/linoleic acid bleaching method were used to determine antioxidative activity of the oils [4, 6].

The major constituents of the wild plant oil were thymol (64.61%), carvacrol (6.35%), γ-Terpinene (6.20%) and p-Cymene (5.40%). The main components of the cultivated plant oil were thymol (49.58%), p-Cymene (14.23), γ-Terpinene (10.17%) and Trans-Caryophyllene (3.15%) (Table 1). The thymol was the most abundant constituents reported in a previous study [7]. In both cultivated and wild plants the oxygenated monoterpenes were the major compounds. The oil of wild plant exhibited a more prominent antibacterial activity. The oil of wild plant showed stronger antioxidative activity compared to that of cultivated plant. The more prominent antibacterial and antioxidative activity could result from the higher content of oxygenated monoterpenes in the oil of wild plant [4].

Table 1: Chemical Composition of the Essential oils of Wild and Cultivated Plant of Thymus vulgaris.

RI: Retention indices (HP-5MS column).

 Table 2: Antibacterial Activity (MIC in µg/mL) of the Essential Oil Wild and Cultivated Plant of Thymus vulgaris.

Table 3: Antioxidative Activity of the Essential Oil Wild and Cultivated Plant of Thymus vulgaris ^a

^a Values are expressed as means ± SD of three parallel measurements.

^b Positive controls

References

1. W. Letchamo, H. L. Xu, and A. Gosselin, J. Plant Physiol., 147, 29 (1995).
2. S. A. L. Jackson, and R. K. M, Hay, Ann. Hort. Sci., 69, 275 (1994).
3. L. Tabrizi, A. Koocheki, Moghaddam, P. R, and M. N. Mahallati, Chem. Nat. Compd., 46, 121 (2010).
4. S. S. Saei-Dehkordi, H. Tajik, Moradi, M, and F. Khalighi-Sigaroodi, Food Chem. Toxicol., 48, 1562 (2010).
5. NCCLS (National Committee for Clinical Laboratory Standards), Approved Standard, M7-A5 (2000).
6. H. E. Miller, J. Am. Oil. Chem. Soc., 48, 91 (1971).
7. M. Razzaghi-Abyaneh, M. Shams-Ghahfarokhi, M. B. Rezaee, K. Jaimand, S. Alinezhad, R. Saberi, and T. Yoshinari, Food Control., 20, 1018 (2009).