3C Viral Proteases Ampelopsis Ampelopsis grossedentata Ampelopsis grossedentata extract Antiviral Agents Article Binding Sites Covalent inhibitors Cysteine Flavonoids Flavonols IC50 Mass Spectrometry Models, Molecular Molecular Docking Simulation Molecular Dynamics Simulation Plant Extracts Protease Inhibitors Protein Binding Protein Conformation SARS-CoV-2 SARS-CoV-2 3CLpro Severe acute respiratory syndrome coronavirus 2 antivirus agent binding site chemical composition chemistry controlled study coronavirus 3C protease covalent bond