Anti-SARS-CoV-2 and Antioxidant Activities of The Methanolic Extract and Its Fractions of Marrubium alysson L. Aerial Parts

The pandemic novel coronavirus disease 2019 (COVID-19) has resulted in enormous economic damage and an exclusive health crisis, so developing a cure for this respiratory infectious disease has proceeded forward at full speed. Natural products and herbal medicines with accepted safety profiles are considered promising sources for discovering new medication leads. Genus Marrubium was reported to exhibit potential antiviral and antioxidant activities. Thus, this study aims to evaluate the inhibitory activity of the total methanolic extract and its soluble fractions: (petroleum ether, methylene chloride, and ethyl acetate) of the aerial parts of Marrubium alysson L . against SARS-CoV-2 main protease (M pro ). Also, they were quantitatively assayed for their phenolics and flavonoids contents, in addition to evaluating their antioxidant activity. The results showed that the petroleum ether fraction has the highest inhibitory activity against SARS-CoV-2 main protease (M pro ) enzyme with IC 50 value of 3.959±0.17 µg/mL compared to the reference tipranavir (IC 50 1.89±0.08 µg/mL). The ethyl acetate fraction showed the highest total phenolics and flavonoids contents as well as the highest antioxidant activity (IC 50 33.81±0.15 µg/mL) compared to the reference L-ascorbic acid (IC 50 30.43±0.14 µg/mL). It could be concluded that soluble fractions of the total methanolic extract of Marrubium alysson L . may be used as an alternative source for developing new natural inhibitors against the main protease enzyme and may be suggested for the treatment of COVID-19.