Effect of eucalyptus oil on respiratory bacteria and viruses

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Antibacterial activity of some essential oil components against five foodborne pathogens. Journal of Agricultural and Food Chemistry , 43 , — Skip to search form Skip to main content Skip to account menu You are currently offline. Some features of the site may not work correctly. DOI: Cermelli , A. View on Springer. Save to Library Save. Create Alert Alert.

Share This Paper. Background Citations. Methods Citations. Results Citations. Figures, Tables, and Topics from this paper. Citation Type. Has PDF. As a result, MIC values were calculated and summarized in Table 5. They were determined considering the amount of EOs and the free airspace L in the Petri dish. As control, absolute ethanol did not show any antibacterial effect.

Among the EOs, cinnamon bark was the most effective against all investigated pathogens with MIC values in the range of Besides, thyme volatiles also showed potent inhibition against Haemophilus spp. In the case of peppermint and citronella oils, moderate activities were detected against Gram-negative strains MIC: EO of scots pine did not show any inhibition in VP, except in the case of H. In contrast, vapor of eucalyptus oil effectively inhibited the growth of Haemophilus spp.

In the case of M. Among our tested pathogens, S. In conclusion, we should highlight that Gram-negative strains were more sensitive to EO vapors: we detected higher MIC values against all Gram-positive bacteria.

Antibacterial activity of cinnamon bark, thyme, clove, peppermint, citronella, eucalyptus, and scots pine oils by vapor phase test. Due to the hydrophobic character of EOs, classical microbiological tests are not relevant for detection of the antibacterial activity of these substances, thus, some modifications and development of new techniques is essential for this purpose.

With BDT, we could detect the antibacterial effect of EOs in liquid medium; however, the inhibitory effect of volatiles could be determined with VPT [ 10 ]. The EOs application via inhalation is becoming more frequent nowadays, especially in the case of bacterial infections of the respiratory tract [ 7 ]. Classical antibacterial assays did not model the circumstances of inhalation; moreover, they usually focus on the activity of EOs via direct contact.

In opposite, VPT detect the effect of gaseous phase produced by EO vapor and they can be easily combined with other techniques [ 8 ]. It should be highlighted that VPT can also be adapted to other different pathogens such as fungi and viruses [ 15 — 18 ]. According to the result of the microbiological assays, cinnamon bark, clove, thyme, peppermint, and citronella oils showed the most potent activity in both vapor and liquid systems.

Therefore, they could be promising alternatives to support the current general treatment of bacterial infections. In liquid form, cinnamon bark was the most effective against S. In the case of S. Cinnamon bark and thyme were equally active against this pathogen, which was in accordance with previous results [ 5 ]. Interestingly, Mulyaningsih et al. Because we used EO distilled from the leaves, we suggest that the difference is probably caused by the compositions of the eucalyptus oils in the experiments [ 20 ].

Parallel to our results, a previous publication has reported the same inhibitory trend and cited strong antibacterial character of cinnamon bark and cinnamaldehyde against S.

Against this pathogen, antibiofilm activity of eucalyptus oil was also published [ 22 ]. Between Haemophilus spp. Among our test materials, we detected the best inhibition in the case of cinnamon bark followed by thyme and clove, which was in accordance with previous observations [ 23 , 24 ]. However, eucalyptus oil and its vapor was previously reported as promising solutions against respiratory viruses e. Influenza Virus type A and mumps virus , their antibacterial value in several studies were less potent than the antiviral effect [ 16 , 25 ].

According to other reports, which support our findings, eucalyptus oil could be a more potent inhibitor of Haemophilus species in contrast with S. The same potency was observed previously by Dorman et al. This observation was parallel to our experience in liquid media. Cinnamon bark volatiles were equally active against H. Our observations were in accordance with previous reports [ 9 ].

Houdkova et al. Except in the case of H. In conclusion, we must highlight cinnamon bark as the most active EO in both in vitro systems. Besides, thyme, citronella, and peppermint oil and vapor also had strong antibacterial effect. At lower concentrations, clove oil was a more potent inhibitor in liquid phase; in vapor form it showed activity against H.

Unfortunately, eucalyptus oil and its vapor were only active in higher concentrations. EOs were highlighted, if the MIC values were lower than 0.

On the whole, we must emphasize that our EOs were more potent inhibitors in liquid form which is probably due to the direct contact with the pathogen. According to previous publications, EOs could interact with bacteria in many different ways such as alteration of the cell morphology, membrane permeability, and inhibition of enzymes [ 8 , 19 ]. Several studies reported that Gram-positive bacteria were more sensitive to EOs and their components [ 28 — 30 ] than Gram-negative bacteria. Interestingly, we found that Gam-negative pathogens required less EO for their total inhibition in our both systems.

We suggest that this is partly due to the fact that S. Our observation was in correlation with the results of Inouye et al. The reason for this phenomenon is not fully understood; however, the authors pointed out that the outer membrane of H. However, it should be taken into consideration that due to their lipophilic character they require effective formulation to achieve the proper activity in the respiratory tract.

In the case of EOs, the in vitro antimicrobial assays should be optimized because of their hydrophobic character and multicomponent composition. Based on our results, we suggest that VPT provides the best detection for the activity of EOs based on gaseous contact. However, BDT is one of the most suitable direct-contact assays.

On the other hand, the evaluation of antibacterial activity it should be taken into consideration that EOs have different characters in liquid form or in VP which results in diverse biological activity. We conclude that cinnamon bark oil possess the strongest antibacterial activity against all the respiratory tract pathogens used in our study.

On the whole, it should be highlighted that cinnamon, thyme, peppermint, and citronella also showed potent antimicrobial activity in vapor and in liquid form; in contrast, clove oil was more potent inhibitor in liquid phase. Finally, in vitro and clinical studies are also required to calculate the effective doses of EOs, determine the interactions between the components and reveal their toxicity. BK and VLB supervised the microbiological methods. AB performed the characterization of the essential oils with GC.

GYH supervised the work and corrected the manuscript for publication. BT revised the manuscript critically and grammatically. Inouye S, Yamaguchi H, Takizawa T Screening of antibacterial effect of a variety of essential oils on respiratory tract pathogens, using a modified dilution assay method.

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