Chemical analysis, antimicrobial and anti-oxidative properties of Daucus gracilis essential oil and its mechanism of action

Objective To evaluate the essential oils (EO) composition, antimicrobial and antioxidant power of a local plant, Daucus gracilis ( D. gracilis ). Methods The aerial parts of D. gracilis were subjected to hydro distillation by a Clevenger apparatus type to obtain the EO which had been analyzed by gas chromatography and gas chromatography coupled with mass spectrometry, and screened for antimicrobial activity against five bacteria and three fungi by agar diffusion method. The mechanism of action of the EO was determined on the susceptible strains by both of time kill assay and lysis experience. The minimal inhibitory concentrations were determined by agar macro-dilution and micro-dilution methods. Anti-oxidative properties of the EO were also studied by free diphenyl-2-picrylhydrazyl radical scavenging and reducing power techniques. Results The EO yielded 0.68 (v/w). The chemical analysis presented two dominant constituents which were the elemicin (35.3%) and the geranyl acetate (26.8%). D. gracilis EO inhibited the growth of Bacillus cereus and Proteus mirabilis significantly with minimal inhibitory concentrations of 17.15 μg/mL by the agar dilution method and 57.05 μg/mL and 114.1 μg/mL, respectively by liquid micro-dilution. A remarkable decrease in a survival rate as well as in the absorbance in 260 nm was recorded, which suggested that the cytoplasm membrane was one of the targets of the EO. The EO showed, also, important anti-oxidative effects with an IC 50 of 0.002 mg/mL and a dose-dependent reducing power. Conclusions D. gracilis EO showed potent antimicrobial and anti-oxidative activities and had acted on the cytoplasm membrane. These activities could be exploited in the food industry for food preservation.