2021 Volume 64 Issue 3 Pages 237-247
Purpose: Prevention of SARS-CoV-2 infection is crucial for overcoming the COVID-19 epidemic. Therefore, it is necessary to take new precautionary measures in addition to disinfecting hands and wearing personal protective equipment (PPE). One of the candidates for prevention is the use of catechins, particularly epigallocatechin-3-Ο-gallate (EGCG). It has been reported that EGCG selectively binds to the spike protein of SARS-CoV-2 by the molecular docking method, which may inhibit the binding of the spike protein to angiotensin converting enzyme-2 (ACE2). The purpose of this study was to investigate whether each of EGCG alone, a mixture of four kinds of catechins, or green tea effectively inhibited the binding of the SARS-CoV-2 spike protein to ACE2.
Materials and Methods: Catechins in different states (EGCG, four types of mixed catechins, powdered green tea) were used in this study. The effects of EGCG solution (EGCG) and four kinds of mixed catechins solution (4 KC) were examined at three different concentrations (1, 10 and 100 mg/ml), and two types of green tea solution, Ⅰ (PWA) and Ⅱ (PWB), at two different concentrations (1 and 10 mg/ml) were adopted. A screening kit for SARS-CoV-2 spike protein inhibition was used and the reaction was developed with a tetramethylbenzidine (TMB) substrate. Thereafter, the coloring reaction was photographed and inhibitory level was measured by ELISA.
Results and Discussion: The inhibitory effect of ACE2 binding to SARS-CoV-2 spike protein was the strongest at high concentration in each solution, and the inhibitory effect decreased in proportion to the decrease of concentration. The percentages of inhibitory effect ranged from 12 to 89% for EGCG, from 11 to 88% for 4 KC, from 10 to 47% for PWA, and from 11 to 47% for PWB. In the present study, it was found that four kinds of catechins mixed solution and green tea solution inhibited binding of the spike protein to ACE2 the same as the EGCG solution, and that the inhibitory effect of each solution depended on the concentration.
Conclusion: This study showed that not only EGCG, but also the mixture of four kinds of catechins and the powdered green tea effectively inhibited the binding of SARS-CoV-2 spike protein depending on the concentration. Catechins are expected to serve as a new way to prevent SARS-CoV-2 infection.
