Comparative study of essential oils composition and in vitro antibacterial effects of two subspecies of Daucus carota growing in Tunisia

Abstract Essential oils possessing several therapeutic benefits are considered of a paramount importance in human life. They have been used since antiquity in flavour as condiments and in medicine as antimicrobial agents. Carrot is one of the main vegetables displaying numerous interesting nutritional and pharmacological benefits. The present study was undertaken to determine the interspecific chemical variability and evaluate the antibacterial effects of the essential oils from two Daucus carota subspecies; D. carota subsp. drepanensis (Lojac.) Heywood (EOCD) and D. carota subsp. hispidus (Ball) Heywood (EOCH) growing wildly in Tunisia. Analysis of both resulting essential oils using gas chromatography-flame ionization detector (GC/FID) and GC-mass spectrometry (GC/MS) allowed to observe variations in contents of the main constituents. Thus, sixty-two volatiles representing respectively, 98.6% (EOCD) and 98.3% (EOCH) of the total essential oils were identified. Major constituents are (E)-methyl isoeugenol (58.7%) and elemicin (24.3%) for (EOCD) and α-cadinol (13.6%), premnaspirodiene (11.4%) and (E)-methyl isoeugenol (11.4%) for (EOCH). Both essential oils were individually tested against the pathogenic strains: Salmonella typhimurium ATCC 1408, Escherichia coli ATCC 35218, Staphylococcus aureus ATCC 25923 and Enterococcus faecalis ATCC 29212. The inhibitory effect of D. carota subs. hispidus essential oils was detected over all the strains studied, the MIC ranged from 1.25 to 2.50 mg mL−1.