Saponin and its derivatives (glycyrrhizin) and SARS-CoV-2

Saponins, the glycosidic compounds, are the subclass of terpenoids that are exceedingly diverse and largest group of natural products found in plants. Based on the aglycone structure, saponins can be classified as triterpenoid, steroidal, and alkaloidal saponins. Glycyrrhizin is a triterpenoid saponin from the root and rhizome concentrates of Liquorice (Glycyrrhiza glabra). Saponin triterpene glycyrrhizin plays an important role in various activities and applications, including molluscicidal, anti-inflammatory, anti-allergic, antidiabetic, cytotoxic, antitumor, antifungal, antibacterial, antiparasitic, and antiviral. The traditional glycyrrhizin therapy is effective for treating a variety of clinical conditions. Due to the wide range of pharmacological properties, it is commonly used in COVID-19 patients. It inhibits replication of respiratory viruses, causes cytopathological effects, and could be an auxiliary medication for COVID-19 treatment due to its liver-protective properties. This chapter discusses biological and nutraceutical applications of saponins and glycyrrhizin in detail.