The effect of Glycyrrhiza glabra extracts on inhibiton of 3Clpro

Abstract

The Sars-CoV-2 virus causes the COVID-19 disease, which is characterized by high mortality rate and symptoms such as severe acute respiratory failure. However, it has been proven that the 3-chymotrypsin-like protease (3Clpro) enzyme, which plays a key role in the replication of the Sars-CoV-2 virus, can be inhibited by certain natural compounds with a flavonoid structure. Flavonoids interact with the active site of the enzyme, resulting in enzyme inhibition. In this project, the aim was to determine the inhibitory concentrations of flavonoid molecules on 3Clpro and obtain the most effective extracts of licorice root (Glycyrrhiza Glabra L.), which is known to contain high levels of these molecules. The goal of our project is to investigate the effects of extracts obtained from licorice root using different extraction methods on the inhibition of the 3Clpro enzyme and their potential role in the treatment of Sars-CoV-2 virus infection. In our study, the phenolic content of these natural products was determined for the first time using LC MS/MS, and the inhibitory effect of these natural product extracts on the 3Clpro enzyme was also studied for the first time. When licorice root extracts were evaluated in terms of antioxidant parameters, the highest TEAC, FRAP, and DPPH levels were observed particularly in ethanol extracts. The extracts that showed the highest inhibition effect for the 3-CLpro enzyme of licorice root were respectively obtained by soaking at 80°C for 6 hours, soaking in an ultrasound bath for 20 minutes, soaking in water at 40°C for 24 hours, soaking in 60% ethanol, and soaking in 80% ethanol. The most studied bioactive compounds of licorice root in the literature are glycyrrhizin, glycyrrhetinic acid, isoliquiritin, and isoflavones. However, in this study, the phenolic acid and flavonoid content, which are not widely covered in the literature, were also examined. Among the compounds studied in licorice root, the most abundant compounds were found to be apigenin, pelargonin, cyanidin, maleic acid, ethyl ferulate, and chlorogenic acid