Comparative study of essential oils from fennel fruits and anise fruits: Chemical composition and in vitro antimicrobial activity

Abstract

Fennel (Foeniculum vulgare Mill.) and anise (Pimpinella anisum L.) are well-known aromatic plants with traditional use as medicinal and culinary spices and herbs. As part of a broader study, the aim of this investigation was to determine the chemical composition of fennel fruit essential oil (Foeniculi fructus aetheroleum, FFA) and anise fruit essential oil (Anisi aetheroleum, AA) and to assess their antimicrobial potential. Hydrodistilled FFA from fruits gathered in central Macedonia was subjected to physico-chemical analysis, as well as commercial AA, which was obtained from a local vendor. The chemical composition of both essential oils was determined using gas chromatography with mass spectrometric detection. The main component of both essential oils was trans-anethole. The antimicrobial action of both essential oils (FFA and AA) was tested against several bacterial cultures and compared to standard antimicrobial agents. The microorganisms used in this research were Gram-positive bacteria (Bacillus pumilus NCTC 8241, Staphylococcus aureus ATCC 6538,), Gram-negative bacteria (Escherichia coli ATCC 8739 and Pseudomonas aeruginosa ATCC 9027), and fungi (Saccharomyces cerevisiae ATCC 9763 and Candida albicans ATCC 10231). The microdilution test enabled determination of the minimal inhibitory concentration (MIC) of all samples used in the experiment against all of the test microorganisms. It was concluded that FFA and AA have moderate antibacterial activity and affect the growth of the Gram positive and the Gram negative bacteria. On the other, they are potent antifungal agents and affect the growth of S. cerevisiae ATCC 9763 and C. albicans ATCC 10231. AA was observed to have a slightly higher antimicrobial activity when compared to FFA. Based on the chemical composition of the samples, a connection was proposed between the trans-anethole content of the essential oils and their antimicrobial properties.