The emergence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) resulted in the coronavirus disease 2019 (COVID-19) pandemic. Given the advent of subvariants, there is an urgent need to develop novel drugs. The aim of this study was to find SARS-CoV-2 inhibitors from Scutellaria baicalensis Georgi targeting the proteases 3CL^pro and PL^pro. After screening 25 flavonoids, chrysin 7-O-β-D-glucuronide was found to be a potent inhibitor of SARS-CoV-2 on Vero E6 cells, with half-maximal effective concentration of 8.72 µM. Surface plasmon resonance assay, site-directed mutagenesis and enzymatic activity measurements indicated that chrysin-7-O-β-D-glucuronide inhibits SARS-CoV-2 by binding to H41 of 3CL^pro, and K157 and E167 of PL^pro. Hydrogen-deuterium exchange mass spectrometry analysis showed that chrysin-7-O-β-D-glucuronide changes the conformation of PL^pro. Finally, chrysin 7-O-β-D-glucuronide was shown to have anti-inflammatory activity, mainly due to reduction of the levels of the pro-inflammatory cytokines interleukin (IL)-1β and IL-6.

严重急性呼吸综合征冠状病毒-2 (SARS-CoV-2) 的出现导致了 2019 年冠状病毒病 (COVID-19) 大流行。鉴于亚变体的出现，迫切需要开发新药。本研究的目的是从黄芩中寻找针对蛋白酶 3CL ^pro 和 PL ^pro 的 SARS-CoV-2 抑制剂。经过对25种黄酮类化合物的筛选，发现白杨素7-O-β-D-葡萄糖醛酸苷是Vero E6细胞上SARS-CoV-2的强效抑制剂，半数有效浓度为8.72 µM。表面等离振子共振分析、定点突变和酶活性测量表明，chrysin-7-O-β-D-glucuronide 通过与 3CL ^pro 的 H41 以及 K157 和 E167 结合来抑制 SARS-CoV-2 PL ^pro 。氢氘交换质谱分析表明chrysin-7-O-β-D-glucuronide改变了PL ^pro 的构象。最后，白杨素 7-O-β-D-葡萄糖苷酸被证明具有抗炎活性，这主要是由于促炎细胞因子白细胞介素 (IL)-1β 和 IL-6 水平的降低。