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Research Database –
International Updates
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Issue 68
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.
Methods: 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.
Discussion: Both TTO and EUO were able to exert a direct antiviral effect on HSV in vitro. The active antiherpes components of TTO and EUO are not yet known. However, these essential oils offer promise as possible antiviral agents for recurrent herpes infection.
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.

Comments: 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.

GOVINDAN and GOVINDAN, Department of Chemistry, Fitchburg State College, Fitchburg, MA 01420, USA, mgovindan@fsc.edu, evaluated the usefulness of thin-layer chromatography (TLC) as a method of determining the quality of the herbal product goldenseal (Hydrastis canadensis).
Background: Goldenseal is one of the top five herbal supplements in the international market.
Methods: 10 goldenseal samples were analysed by TLC using two solvent systems and spray reagents.
Results: Five samples contained both hydrastine and berberine, four contained berberine only, and one did not contain either of these alkaloids. The TLC results were confirmed by high-pressure liquid chromatography (HPLC).
Conclusion: TLC is a convenient method of determining the quality and possible adulteration of goldenseal products.
Govindan M, Govindan G. A convenient method for the determination of the quality of goldenseal. Fitoterapia 71 (3): 232-5. Jun 2000.


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Julia Chen

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