Autophagy activation and antiviral activity by a licorice triterpene.

The triterpene glycyrrhizic acid (GRA), the main product from the Glycyrrhiza glabra medicinal plant, is known for its antiinflammatory and antimicrobial activity. In this work, GRA was studied for its ability to induce the autophagic process activator Beclin 1 in epithelial cells and to observe how this property could influence its antiviral activity. After 24 h of treatment, GRA induced a Beclin 1 production that was more than twofold higher than that produced by rapamycin, used as a reference compound. When the compounds were added to HeLa cells together with the viruses, GRA demonstrated a strong antiherpes simplex virus type 1 (HSV1) activity, whereas rapamycin had no activity. However, if the compounds were added to the cells 24 h before the viruses, GRA induced the production of an even higher amount of Beclin 1 and showed an improved antiviral effect; under these conditions, rapamycin was also able to exert a significant anti-HSV1 activity. In conclusion, GRA is a strong inducer of the autophagy activator Beclin 1, which establishes a resistance state to HSV1 replication.