Anti-SARS-CoV-2 activity of various PET-bottled Japanese green teas and tea compounds in vitro

The outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a serious threat to global public health. The emergence of SARS-CoV-2 variants is a significant concern regarding the continued effectiveness of vaccines and antiviral therapeutics. Thus, natural products such as foods, drinks, and other compounds should be investigated for their potential to treat COVID-19. Here, we examined the in vitro antiviral activity against SARS-CoV-2 of various polyethylene terephthalate (PET)-bottled green Japanese teas and tea compounds. Six types of PET-bottled green tea were shown to inhibit SARS-CoV-2 at half-maximal inhibitory concentrations (IC(50)) of 121- to 323-fold dilution. Our study revealed for the first time that a variety of PET-bottled Japanese green tea drinks inhibit SARS-CoV-2 infection in a dilution-dependent manner. The tea compounds epigallocatechin gallate (EGCG) and epicatechin gallate showed virucidal activity against SARS-CoV-2, with IC(50) values of 6.5 and 12.5 µM, respectively. The investigated teas and tea compounds inactivated SARS-CoV-2 in a dose-dependent manner, as demonstrated by the viral RNA levels and infectious titers. Furthermore, the green teas and EGCG showed significant inhibition at the entry and post-entry stages of the viral life cycle and inhibited the activity of the SARS-CoV-2 3CL-protease. These findings indicate that green tea drinks and tea compounds are potentially useful in prophylaxis and COVID-19 treatment. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00705-022-05483-x.