Combined effects of flavonoids and acyclovir against herpesviruses in cell cultures

The combined antiviral effects of some flavonoid compounds and acycloguanosine (acyclovir, Zovirax) were studied on the multiplication of herpes simplex virus types 1 and 2 in HEp-2 cells and on pseudorabies (Aujeszky) virus in chick embryo fibroblast cells by the yield reduction method. The flavonoids quercetin, quercitrin (quercetin-3-L-rhamnoside) and apigenin exhibit antiviral activity against these herpesviruses, and acyclovir is currently one of the most effective antiherpetic agents. In these studies, the simultaneous application of flavonoids with acyclovir resulted in an enhanced antiviral activity. A mathematical formula was used to interpret the drug interaction, resulting in FIC (fractional inhibitory concentration) indices. Meaning a synergic interaction, all combinations exhibited synergy, FIC values of 0.6-0.8 being commonly observed.