Insight into the Biological Activity of Zingiber officinale var. Amarum Extracts as Antioxidant and SARS-CoV-2 Inhibitor In-Silico

Zingiber officinale var. Amarum (Ginger) is a medicinal spice of the Zingiberaceae family. Its medicinal value can be attributed to its secondary metabolites, such as flavonoids, terpenoids, gingerols, and shogaols, which posses potent antioxidant properties. This study aimed to evaluate the effect of extraction solvent on the total flavonoid content, and antioxidant activity of emprit ginger, and to determine the anti-SARS-CoV-2 activity of major compounds of ginger in silico. Emprit ginger was extracted by refluxing seperately with ethanol, ethyl acetate, and n-hexane. The extracts were tested for the presence of flavonoid, and the total flavonoid content was determined by the aluminium chloride colorimetric method. The antioxidant activity of the extracts was assessed using the 2,2’-azino-bis (3ethylbenzotiazolin)-6-sulfonic acid (ABTS) radical scavenging assay. Anti-SARS-CoV-2 activity of major phenolic and flavonoid compounds of ginger including catechin, epicatechin, rutin, naringenin, quercetin, gingerol, and zingiberol was determined in silico by molecular docking with SARS-CoV-2 main protease (Mpro). Emprit ginger extracts contained flavonoids with total flavonoid contents of 103.93 mgQE/g, 97.32 mgQE/g, and 81.5 mgQE/g for ethyl acetate, n-hexane, and ethanol extracts, respectively. The ethyl acetate extract had the highest antioxidant activity with IC50 value of 20.02 µg/mL. Emprit ginger ligands showed strong interactions with SARS-CoV-2 main protease (Mpro) with binding energies ranging from -4.80 to 9.90 kcal/mol. Gingerol and zingiberol exhibited the most promising anti-SARS-CoV-2 activity in silico with binding energies of -4.80 and -5.30 kcal/mol. The study revealed emprit ginger as a source of natural antioxidant with promising anti-SARS-Cov-2 activity.