Chemical Composition and Anti-SARS-CoV-2 Activity of the Leaves Methanolic Extract of Silybum marianum (L.) Gaertn.

Abstract

In line with the global interest and demand in finding sustainable ways to counteract the emerging viral pandemics, our study highlights the unique composition and anti-SARS-CoV-2 activity of a barely used and studied part of the famous medicinal plant Silybum marianum (L.)Gaertn.Various chromatographic and spectroscopic techniques used in the process of isolation and structure elucidation led to the identification of nine flavonoids for the first time from the methanolic leaves extract.Among them,the aglyconeacacetin (2)was isolated for the first time from the genus. The antiviral activity of the extract against SARS-CoV-2 main protease showed considerable activity with half-maximal inhibitory and cytotoxic concentrations; IC50=80.5 µg/ml and CC50=576.5 µg/ml, respectively indicating a relatively high selectivity; SI = 7.1..