Positive Health Online

Abstract

SCHNITZLER and colleagues, Department of Virology, Hygiene Institute, University of Heidelberg, Germany, examined the antiviral effects of Australian tea tree oil (TTO) and eucalyptus oil (EUO) against herpes simplex virus (HSV) in vitro.

Background

Methodology

A standard neutral red dye uptake assay was used to evaluate cytotoxicity of TTO and EUO on RC-37 cells in vitro. A plaque reduction assay was used to test antiviral activity of TTO and EUO in RC-37 cells infected with either HSV type 1 (HSV-1) or HSV type 2 (HSV-2) in vitro. Virucidal activities of TTO and EUO were also assessed in viral suspension tests . To determine the mode(s) of antiviral action of TTO and EUO: either RC-37 cells were pretreated with TTO or EUO before infection, or viruses were incubated with TTO or EUO before infection, during adsorption or after penetration into EC-37 cells.

Results

Cytotoxicity of TTO and EUO on RC-37 cells was moderate and approached 50% (TC50) at concentrations of 0.006% and 0.03% respectively. The IC50 (50% inhibitory concentration) of TTO for HSV-1 and HSV-2 plaque formation was 0.0009% and 0.0008% respectively. The IC50 of EUO for HSV-1 and HSV-2 was 0.009% and 0.008% respectively. Non- cytotoxic concentrations of TTO significantly reduced HSV-1 and HSV-2 plaque formation by 98.2% and 93.0% respectively. Non-cytotoxic concentrations of EUO reduced HSV-1 and HSV-2 virus titres by 57.9% and 75.4% respectively (non-significant). When HSV was pretreated with TTO or EUO prior to adsorption into EC-37 cells, plaque formation was clearly reduced.

Conclusion

References

Schnitzler P et al. Antiviral activity of Australian tea tree oil and eucalyptus oil against herpes simplex virus in cell culture. Die Pharmazie 56 (4): 343-7. Apr 2001.

Comment

These very promising results show that tea tree and eucalyptus oils are effective against herpes simplex virus in vitro. Further research will establish whether these results can be replicated in vivo.