In vitro antiviral activity of Melaleuca alternifolia essential oil

Lett Appl Microbiol. 2009 Dec;49(6):806-8. doi: 10.1111/j.1472-765X.2009.02740.x. Epub 2009 Sep 18.


Aims: To investigate the in vitro antiviral activity of Melaleuca alternifolia essential oil (TTO) and its main components, terpinen-4-ol, alpha-terpinene, gamma-terpinene, p-cymene, terpinolene and alpha-terpineol.

Methods and results: The antiviral activity of tested compounds was evaluated against polio type 1, ECHO 9, Coxsackie B1, adeno type 2, herpes simplex (HSV) type 1 and 2 viruses by 50% plaque reduction assay. The anti-influenza virus assay was based on the inhibition of the virus-induced cytopathogenicity. Results obtained from our screening demonstrated that the TTO and some of its components (the terpinen-4-ol, the terpinolene, the alpha-terpineol) have an inhibitory effect on influenza A/PR/8 virus subtype H1N1 replication at doses below the cytotoxic dose. The ID(50) value of the TTO was found to be 0.0006% (v/v) and was much lower than its CD(50) (0.025% v/v). All the compounds were ineffective against polio 1, adeno 2, ECHO 9, Coxsackie B1, HSV-1 and HSV-2. None of the tested compounds showed virucidal activity. Only a slight virucidal effect was observed for TTO (0.125% v/v) against HSV-1 and HSV-2.

Conclusions: These data show that TTO has an antiviral activity against influenza A/PR/8 virus subtype H1N1 and that antiviral activity has been principally attributed to terpinen-4-ol, the main active component.

Significance and impact of the study: TTO should be a promising drug in the treatment of influenza virus infection.

MeSH terms

  • Antiviral Agents / pharmacology*
  • Drug Resistance, Viral / drug effects
  • Enterovirus / drug effects
  • Influenza A Virus, H1N1 Subtype / drug effects*
  • Inhibitory Concentration 50
  • Insecticides / pharmacology
  • Microbial Sensitivity Tests
  • Monoterpenes / pharmacology*
  • Simplexvirus / drug effects
  • Tea Tree Oil / pharmacology*


  • Antiviral Agents
  • Insecticides
  • Monoterpenes
  • Tea Tree Oil