The Effect of Aqueous Extract of Glycyrrhiza glabra on Herpes Simplex Virus 1

BACKGROUND: Herpes Simplex Virus 1 (HSV-1) resistance to drugs and the side effects of drugs have drawn the attention of investigators to herbal plants. OBJECTIVES: The main aim of the current research was to investigate the effects of Glycyrrhiza glabra (liquorice root) on HSV-1. One of the objectives of the current research was to determine the efficacy and the effect of the elapsed incubation time of treating the Vero cells infected with HSV-1 by G. glabra. In addition, the effect of cells pretreatment with licorice root extract, preincubation of virus with licorice root extract, and the antiviral activity were assessed. PATIENTS AND METHODS: Vero cells were incubated after adding different concentrations of aqueous extracts of G. glabra. The cells were incubated during various time courses. Cytotoxicity assay, determining the 50% tissue culture infectious dose (TCID(50)), and incubation of HSV-1 with licorice root extract prior to viral infection were performed. RESULTS: Internal association among different experiment groups showed the significant difference in the efficacy of the extract with regard to incubation period between one and four hours, one and eight hours, four and 12 hours, and eight and 12 hours. Moreover, there was a significant difference with regard to efficacy among the pretreatment of cells with extract for two hours, incubation of virus with extract for one hour, incubation of virus with extract for two hours. CONCLUSIONS: G. glabra showed the characteristics of a novel antiviral medication; however, more in vitro experiments are needed to determine the antiherpetic activities of the G. glabra.