Chrysin 7-O-β-D-glucuronide, a dual inhibitor of SARS-CoV-2 3CLpro and PLpro, for the prevention and treatment of COVID-19

The evolution of SARS-CoV-2 virus has resulted in the global pandemic COVID-19. Given the advent of subvariants, it is urgent to develop novel drugs. This work aims to discover SARS-CoV-2 inhibitors from Scutellaria baicalensis Georgi targeting the proteases 3CLpro and PLpro. After screening 25 flavonoids, we revealed that chrysin 7-O-β-D-glucuronide could potently inhibit SARS-CoV-2 on Vero E6 cells, with EC50 of 8.72 μM. Surface plasmon resonance, site-directed mutagenesis and enzymatic activity measurements indicated chrysin-7-O-β-D-glucuronide inhibits SARS-CoV-2 through binding to H41 of 3CLpro, and K157 and E167 of PLpro, and hydrogen-deuterium exchange mass spectrometry analysis showed PLpro conformation has remarkable changes caused by chrysin-7-O-β-D-glucuronide. Finally, we revealed anti-inflammatory activity of chrysin 7-O-β-D-glucuronide mainly caused by decreasing level of proinflammatory cytokines IL-1β and IL-6.