Antimicrobial activity of three essential oils (cinnamon, manuka, and winter savory), and their synergic interaction, against Listeria monocytogenes

Abstract

Essential oils (EOs) are categorized as having antimicrobial, insecticidal, and antioxidant activities. For their antibacterial activity, EOs are widely studied as alternatives to antibiotics in human and veterinary medicines. The inhibitory and bactericidal activities of three EOs (Cinnamomum zeylanicum, Leptospermum scoparium, and Satureja montana) were determined against Listeria monocytogenes ATCC 7644. The chemical compositions of the EOs were determined through gas chromatography mass spectrometry (GC‐MS). Essential oils were tested alone or in binary and ternary combinations for both their inhibitory and their bactericidal activities. Binary and ternary mixtures were tested through a chequerboard assay, and thus fractional inhibitory and fractional bactericidal concentration indices were obtained in relation to the activity of each EO alone. The chemical composition of each EO had different percentages of the main classes of compounds. EOs showed high levels of monoterpenes (hydrocarbons and oxygenated), sesquiterpenes (hydrocarbons and oxygenated), and phenylpropanoids for winter savory, manuka, and cinnamon, respectively. Several synergistic activities against Listeria monocytogenes were demonstrated in binary and ternary mixtures of the EOs. Mixtures of the EOs tested showed potential for use as antibacterial products; moreover, because of the synergistic activities the mixtures could be used in lower quantities than individual EOs on their own.

Antimicrobial Activity of Some Essential Oils against Methicillin-Susceptible and Methicillin-Resistant Staphylococcus pseudintermedius-Associated Pyoderma in Dogs

“…Furanoeudesma-1,3-diene, a particular compound with antimicrobial activity [37], was also present in high percentage in Commiphora molmol EO (33.7%). The compounds most represented in Leptospermum scoparium EO, which have demonstrated a remarkable antibacterial activity against several bacterial isolates, were cis-calamenene (22.7%) and leptospermone (19.2%), as already reported in a previous study [38].…”

Chemical composition and in vitro antibacterial activity of essential oils from different species of Juniperus (section Juniperus)

“…On the other hand, α‐pinene was also present in all the tested EOs, also in those with a moderate or low activity. This occurrence confirms the hypothesis that this compound could react in with other ones in a synergistic effect 35,36 . The review of Bassolé 37 reported a synergic effect between α‐pinene and limonene.…”

“…This occurrence confirms the hypothesis that this compound could react in with other ones in a synergistic effect. 35,36 The review of Bassolé 37 and S aureus. 39 The Indian Cymbopogon martini studied before 40 revealed the highest sensitivity of its EO against S epidermis and E coli, due to its richness in p-menthadienols (more than 57% of identified fraction whose 14.4% was represented by p-mentha-1, 7 8-dien-2-ol).…”

In Vitro Antibacterial Activity of Manuka (Leptospermum scoparium J.R. et G. Forst) and winter Savory (Satureja montana L.) Essential Oils and Their Blends against Pathogenic E. coli Isolates from Pigs

“…The main compounds in Sm were carvacrol (45.4%), p-cymene (10.3%) and thymol (7.0%), and the most representative in Ls were cis-calamenene (21.4%), leptospermone (18.3%) and flavesone (6.9%). As regards the compounds' concentration in the Sm and Ls Eos, it is interesting to note that Ls and Sm compositions were slightly different from what was reported previously [29]. These little differences may be due to the degradation of components during the refrigerated storage.…”