Antimicrobial activity and in vivo toxicity evaluation of Foeniculum vulgare Mill. essential oil

Abstract

Foeniculum vulgare Mill. (Apiaceae) is commonly known as “fennel”, a small genus of annual, biennial or perennial herbs distributed in central Europe and the Mediterranean region. It is widely cultivated throughout the temperate and tropical regions of the world for its aromatic fruits, which are used mainly as a culinary spice [1]. Fruits and essential oil of F. vulgare are used as flavoring agents in food products, in cosmetic and pharmaceutical products. The essential oil is accredited with antioxidant, antimicrobial, antithrombotic, antidiabetic activities, among others [2].

                In this present work, it was aimed to determine the antimicrobial activity of the pharma grade F. vulgare essential oil. trans-Anethole (68.2%), fenchone (12.8%) and limonene (6.5%) were confirmed as the main constituents; the analysis was performed by GC/FID and GC/MS, simultaneously. Antimicrobial activity of the essential oil was tested against Escherichia coli NRRL B-3008, Bacillus cereus NRRL B3711, Salmonella typhimurium ATCC 13311 and Streptococcus sanguinis ATCC 10556 by a broth microdilution assay [3]. Minimum Inhibitory Concentrations (MIC) were found to be: 6.25, 6.25, 3.12 and 12.5 mg/mL, respectively, suggesting that the antimicrobial activity of the essential oil was relatively low against the tested pathogens. In addition, lethal concentration (acute toxicity) was determined using the in vivo animal alternative Caenorhabditis elegans test [4]. Lethal concentration (LC₅₀, 50% of killed nematodes) for the essential oil was determined to be <25 mg/mL.