Short communication: Antibacterial effects of essential oils from Cinnamomum cassia bark and Eucalyptus globulus leaves-The involvements of major constituents

PLoS One. 2023 Jul 14;18(7):e0288787. doi: 10.1371/journal.pone.0288787. eCollection 2023.

Abstract

Essential oils from Cinnamomum cassia bark and Eucalyptus globulus leaves have been traditionally applied for bacterial infections, through both of aromatherapy and oral application. (E)-cinnamaldehyde and 1,8 cineole have been identified as their major secondary metabolites, and are also generally considered as the main active ingredients responsible for their medicinal applications. However, ethnobotanical doctors still prefer to use whole essentials oils over purified compounds in bacterial infections. We therefore hypothesized that multi-compound extracts might exert better effects than isolated ingredients. In order to verify the hypothesis about advantages of whole materials, we examined antibacterial properties of the 2 plant essential oils in the comparison with their isolated major compounds, such as (E)-cinnamaldehyde and 1,8 cineole. Effects of liquid- and vapor-phase were examined on a set of 6 gram-positive and -negative bacteria, applying broth dilution, agar well diffusion and disc volatilization methods. In all 3 investigations, we observed that whole cinnamon and eucalyptus oils, with the lower concentrations of (E)-cinnamaldehyde (89.1%) and 1,8 cineole (61.2%), were able to induce better effects than the purified active compounds (≥ 99%). These results partly explain the advantages of using whole essential oils over isolated ingredients, and therefore support the application of traditional dosage forms for bacterial infections in ethnomedicine.

MeSH terms

  • Anti-Bacterial Agents / therapeutic use
  • Cinnamomum aromaticum*
  • Eucalyptol
  • Eucalyptus*
  • Microbial Sensitivity Tests
  • Oils, Volatile* / pharmacology
  • Plant Bark
  • Plant Leaves
  • Plant Oils / pharmacology

Substances

  • Oils, Volatile
  • Eucalyptol
  • cinnamaldehyde
  • Anti-Bacterial Agents
  • Plant Oils

Grants and funding

This research is funded by Vietnam National Foundation for Science and Technology Development (NAFOSTED) under the grant number 09/2019/TN. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.