Tea Polyphenols EGCG and Theaflavin Inhibit the Activity of SARS‐CoV‐2 3CL‐Protease <i>In Vitro</i>
Minsu Jang, Yea–In Park, Yeo-Eun Cha, Rackhyun Park, Sim Namkoong, Jin I. Lee, Junsoo Park
Abstract
COVID‐19, a global pandemic, has caused over 750,000 deaths worldwide as of August 2020. A vaccine or remedy for SARS‐CoV‐2, the virus responsible for COVID‐19, is necessary to slow down the spread and lethality of COVID‐19. However, there is currently no effective treatment available against SARS‐CoV‐2. In this report, we demonstrated that EGCG and theaflavin, the main active ingredients of green tea and black tea, respectively, are potentially effective to inhibit SARS‐CoV‐2 activity. Coronaviruses require the 3CL‐protease for the cleavage of its polyprotein to make individual proteins functional. EGCG and theaflavin showed inhibitory activity against the SARS‐CoV‐2 3CL‐protease in a dose‐dependent manner, and the half inhibitory concentration (IC 50 ) was 7.58 μ g/ml for EGCG and 8.44 μ g/ml for theaflavin. In addition, we did not observe any cytotoxicity for either EGCG or theaflavin at the concentrations tested up to 40 μ g/ml in HEK293T cells. These results suggest that upon further study, EGCG and theaflavin can be potentially useful to treat COVID‐19.