The compound that gives licorice its sweet taste could be key to treating several virulent diseases, such as herpes, say researchers.
Unlike the viruses that infect and kill cells, latent viruses hibernate in cells for years and only occasionally stir from their slumber to cause disease symptoms. Five years ago, Ornella Flore, a virologist now at New York University in New York City, and colleagues identified a gene that allows the Kaposi's sarcoma-associated herpes virus (KSHV) to lie low. But if the gene, LANA, is not expressed, the infected cell can't support the virus and dies with the virus inside.
No such compounds were known to block LANA. However, from previous work on other viruses, Flore knew that glycyrrhizic acid (GA), a compound derived from the licorice herb, might be a candidate because it inhibits the growth of related herpes viruses.
So Flore and colleagues treated cells experiencing latent KHSV infection with a drug containing the licorice compound. Four days after being treated with GA, the infected cells were all dead. A second test with infected cells showed that LANA activity was being squelched. "Since the drug targets only latently infected cells," and since latency mechanisms are similar between viruses, GA might work for other latent viruses as well, says Flore, whose team reports its work today in the Journal of Clinical Investigation.
Using a licorice compound to treat herpes "is an exciting and novel approach," says Jeffrey Cohen, a virologist at the National Institutes of Health in Bethesda, Maryland. While licorice has long been used in traditional medicine in Asia, this is the first time it has been mustered against latent viruses, he says.