Scutellaria baicalensis extract and baicalein inhibit replication of SARS-CoV-2 and its 3C-like protease in vitro

• Main Authors: Hongbo Liu, Fei Ye, Qi Sun, Hao Liang, Chunmei Li, Siyang Li, Roujian Lu, Baoying Huang, Wenjie Tan, Luhua Lai
• Format: Article
• Language: English
• Published: Taylor & Francis Group 2021-01-01
• Series: Journal of Enzyme Inhibition and Medicinal Chemistry
• Subjects: covid-19; sars-cov-2; 3c-like protease; scutellaria baicalensis; baicalein
• Online Access: http://dx.doi.org/10.1080/14756366.2021.1873977
• ISSN: 1475-6366; 1475-6374

COVID-19 has become a global pandemic and there is an urgent call for developing drugs against the virus (SARS-CoV-2). The 3C-like protease (3CLpro) of SARS-CoV-2 is a preferred target for broad spectrum anti-coronavirus drug discovery. We studied the anti-SARS-CoV-2 activity of S. baicalensis and its ingredients. We found that the ethanol extract of S. baicalensis and its major component, baicalein, inhibit SARS-CoV-2 3CLpro activity in vitro with IC50’s of 8.52 µg/ml and 0.39 µM, respectively. Both of them inhibit the replication of SARS-CoV-2 in Vero cells with EC50’s of 0.74 µg/ml and 2.9 µM, respectively. While baicalein is mainly active at the viral post-entry stage, the ethanol extract also inhibits viral entry. We further identified four baicalein analogues from other herbs that inhibit SARS-CoV-2 3CLpro activity at µM concentration. All the active compounds and the S. baicalensis extract also inhibit the SARS-CoV 3CLpro, demonstrating their potential as broad-spectrum anti-coronavirus drugs.