Antiviral activity of 5,6,7-trimethoxyflavone and its potentiation of the antiherpes activity of acyclovir

A naturally occurring flavone, 5,6,7-trimethoxyflavone (TMF), isolated from the plant Callicarpa japonica, was subjected to antiviral assays. The compound exhibited relatively high inhibitory effects on herpes simplex virus type 1 (HSV-1), human cytomegalovirus and poliovirus. The anti-HSV-1 action was not due to the inhibition of virus adsorption, entry and viral protein synthesis, but might involve, at least in part, a virucidal activity, which results in a suppression of viral binding to host cells at an early replication stage. TMF and acylovir were synergic in their anti-HSV activities at levels below the 50% inhibitory concentrations for antiviral activity.