Glycyrrhizin is obtained as an extract from licorice root, which is a herb commonly used in traditional Chinese medicine.
Used in Japan primarily to treat hepatitis C, glycyrrhizin has been demonstrated in previous lab research to inhibit against the 2003 SARS virus (SARS-CoV), a member of the same coronavirus family associated with the 2020 pandemic. Glycyrrhizin analysis was done in vitro (outside of a human body in labs) and was shown to be effective in slowing replication of the SARS virus.
One research team has suggested glycyrrhizin's properties could be useful in treating COVID-19, but no further research appears to be underway.