Isolation, structural elucidation and molecular docking studies against SARS-CoV-2 main protease of new stigmastane-type steroidal glucosides isolated from the whole plants of Vernonia gratiosa.

Phytochemical investigation of the whole plants of Vernonia gratiosa Hance. led in the isolation and identification of two new stigmastane-type steroidal glucosides (1-2), namely vernogratiosides A (1), and B (2). Their chemical structures were fully elucidated based on 1 D/2D NMR spectroscopic, HR-ESI-MS data analyses, and by producing derivatives by chemical reactions. The binding potential of the isolated compounds to replicase protein - main protease of SARS-CoV-2 were examined using the molecular docking simulations. Our results show that the isolated steroidal glucosides (1-2) bind to the substrate-binding site of SARS-CoV-2 main protease with binding affinities of -7.2 and -7.6 kcal/mol, respectively, as well as binding abilities equivalent to N3 inhibitor that has already been reported (-7.5 kcal/mol).

SARS-CoV-2 main protease and papain-like protease inhibition by abietane-type diterpenes isolated from the branches of Glyptostrobus pensilis using molecular docking studies.

Using various chromatographic methods, five abietane-type diterpenes were isolated from the branches of Glyptostrobus pensilis for the first time. The chemical structures of the isolates were identified by modern spectroscopic techniques, including 1H and 13C nuclear magnetic resonance spectroscopy and by comparison with the literature. In addition, the binding potential of the isolated compounds to replicase protein, SARS-CoV-2 main protease and papain-like protease, were examined using molecular docking studies. In silico results suggested that G. pensilis as well as abietane-types diterpenes are potential candidates for the prevention and treatment of SARS-CoV-2.