Naturally Available Flavonoid Aglycones as Potential Antiviral Drug Candidates against SARS-CoV-2.

Flavonoids are important secondary plant metabolites that have been studied for a long time for their therapeutic potential in inflammatory diseases because of their cytokine-modulatory effects. Five flavonoid aglycones were isolated and identified from the hydrolyzed aqueous methanol extracts of L., Blanco, and (L.) Nabelek. They were identified as taxifolin (), pectolinarigenin (), tangeretin (), gardenin B (), and hispidulin (). These structures were elucidated based on chromatographic and spectral analysis. In this study, molecular docking studies were carried out for the isolated and identified compounds against SARS-CoV-2 main protease (Mpro) compared to the co-crystallized inhibitor of SARS-CoV-2 Mpro (α-ketoamide inhibitor (), IC = 66.72 µg/mL) as a reference standard. Moreover, screening against SARS-CoV-2 was evaluated. Compounds and showed the highest virus inhibition with IC 12.4 and 2.5 µg/mL, respectively. Our findings recommend further advanced and studies of the examined isolated flavonoids, especially pectolinarigenin (), tangeretin (), and gardenin B (), either alone or in combination with each other to identify a promising lead to target SARS-CoV-2 effectively. This is the first report of the activity of these compounds against SARS-CoV-2.