Chemical Composition of Cyperus rotundus L. Tubers Essential Oil from the South of Tunisia, Antioxidant Potentiality and Antibacterial Activity against Foodborne Pathogens

The chemical composition of Cyperus rotundus L. tubers essential oil from the South of Tunisia was analyzed using GC-FID and GC-MS. Fifty compounds were identified representing 84.6 % of the total oil. A new chemotype was found in Tunisia. This essential oil was characterized by sesquiterpenes abundance (78.3 %) mainly represented by cyperene (15.2 %) and cyperotundone (19.7 %). The essential oil (EO) was further fractionated into three fractions (F1: n-pentane, F2: n-pentane/diethyl ether (95/5) and F3: diethyl ether). The antioxidant activity of the EO and its fractions was tested using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging test and beta-carotene bleaching method. Results showed that the whole EO was more active than the fractions with an effective concentration (EC50) of 0.85 +/- 0.03 mg/mL and an antioxidant activity coefficient (AAC) of 396.0 +/- 2.4. The antimicrobial activity of the EO and its fractions was evaluated using the disc diffusion method against six foodborne pathogens and results showed that Staphylococcus aureus was the most inhibited bacterium with an inhibition diameter of 15.2 +/- 0.8 mm for the whole EO.