Comparison of Chemical Composition, Antioxidant and Antimicrobial Activities of Thymus capitatus L. essential Oils from two Tunisian localities (Sousse and Bizerte)

This study was carried out to evaluate the difference in chemical composition and biological activities of Thymus capitatus essential oils from two ecotypes in Tunisia. The chemical composition was analyzed by gas chromatography coupled with mass spectrometry (GC/MS). The antimicrobial activity was also tested against seven pathogenic bacteria, two fungal species and one yeast strain using the disc-diffusion assay and minimal inhibition concentration values. The antioxidant activity was evaluated by DPPH radical scavenging. Remarkable differences in these two activities and chemical composition of tested oils were recorded between plants from the two geographical provinces. The main constituents in the oil from the Sousse locality were thymol (69.95%), β-ocimene (3.09%), carvacrol (2.56%), α-terpinene (2.25%). Whereas, the major constituents of oil obtained from Bizerte plant were thymol (81.49%), α-cubebene (3.44%), α-terpinene (3.83%), β-ocimene (3.16%). In fact, the essential oil of Bizerte locality show much better antibacterial, antifungal and anticandidal activities against all ten tested microorganisms than that from Sousse. The inhibition zones diameters and minimal inhibition concentration values for seven bacterial and three fungal strains, which were sensitive to the essential oil from two localities, were in the range of 17–40 mm and 0.025–0.4 % (v/v), respectively. In addition, Thymus capitatus oil from Bizerte had the highest antioxidant activity (IC50= 62 mg ml -1 ) than that from Sousse (IC50 = 74 mg ml -1 ). This study showed that Thymus capitatus essential oil may be used as natural antioxidant and preservative in food against the well known causal agents of foodborne diseases and food spoilage.