Antiviral Activity of Dammarane Saponins Against Herpes Simplex Virus I

Abstract

Two dammarane saponins, ginsenoside Rb₁ (GRb₁) and chikusetsusaponin III (Chi III), were investigated for antiviral activity against herpes simplex virus type I using an in vitro plaque elimination assay. Chi III prevented plaque formation at 50 μM, while GRb1 had no effect at 100 μM. Chi III was further examined for effects on virus yield and for cytotoxicity. The ID₅₀ value for virus yield reduction was 29 μM, and cell growth was inhibited by 50% at 66 μM, indicating that Chi III exhibited marginal antiviral selectivity with a therapeutic index of about 2-fold. Although Chi III exhibited an in vitro virucidal effect with an ID₅₀ value of 62 μM, drug treatment for 24 h reduced production of the cell-associated virus as well as the virus present in the medium, indicating Chi III has intracellular inhibitory activity. Intracellular levels of viral proteins were marginally affected at five hours post-infection, indicating Chi III has a minor impact on the early events of infection.

Keywords::

• Saponins
• Herpes simplex virus
• antiviral agent