Inhibitory activity of soyasaponin II on virus replication in vitro.

The antiviral activities of two saponins, soyasaponin I and II, isolated from soybean (Glycine max Merrill) were studied in vitro against herpes simplex virus type 1 (HSV-1). Soyasaponin II was more potent than soyasaponin I as shown by reduction of HSV-1 production. Soyasaponin II was also found to inhibit the replication of human cytomegalovirus, influenza virus, and human immunodeficiency virus type 1. The action was not due to inhibition of virus penetration and protein synthesis, but might involve a virucidal effect. When acyclovir and soyasaponin II were evaluated in combination for anti-HSV-1 activity, additive antiviral effects were observed for this virus.