Planta Med 2008; 74 - PA322
DOI: 10.1055/s-0028-1084320

Efficacy of an aqueous Pelargonium sidoides extract against herpesvirus

S Schneider 1, J Reichling 2, FC Stintzing 3, R Carle 3, P Schnitzler 1
  • 1Hygiene Institute, Dept. Virology, University of Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
  • 2Institute of Pharmacy and Molecular Biotechnology, Dept. Biology, University of Heidelberg, Im Neuenheimer Feld 364, 69120 Heidelberg, Germany
  • 3Institute of Food Sciences and Biotechnology, Hohenheim University, Stuttgart, Germany

The compounds of an aqueous root extract of the African medicinal plant Pelargonium sidoides were analysed by LC-MS spectroscopy and the antiviral effect of this extract against herpes simplex virus was examined in cell culture. Besides predominant coumarins, simple phenolic structures as well as flavonoid and catechin derivatives were identified as major constituents in the Pelargonium extract. The inhibitory activity of this extract against herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2) was tested in vitro on RC-37 cells using a plaque reduction assay and exhibited high antiviral activity against both herpesviruses in viral suspension tests. The 50% inhibitory concentration (IC50) of the aqueous Pelargonium sidoides extract for herpes simplex virus plaque formation was determined at 0.00006% and 0.000005% for HSV-1 and HSV-2, respectively. Herpesvirus infectivity was significantly reduced by more than 99.9% for HSV-1 and HSV-2. Both herpesviruses were significantly inhibited when herpesvirus was incubated with the plant extract or when the extract was added during the adsorption phase, whereas acyclovir demonstrated antiviral activity only intracellularly during replication of HSV. These results indicate that P. sidoides extract affected the virus before penetration into the host cell and reveals a different mode of action when compared to the classical drug acyclovir. Hence this extract is capable to exert an antiviral effect on herpes simplex virus and might be suitable for topical therapeutic use as antiviral drug both in labial and genital herpes infection.