Government and tea associations in Sri Lanka and India are promoting black tea as a way to combat coronavirus.
Principal in both countries seized on research that suggests black tea polyphenols derived during the oxidation of tea catechins could potentially inhibit the ability of the coronavirus to replicate.
RNA (coronavirus) replication is a two-step mechanism that relies on the RdRP (RNA-dependent RNA polymerase) protein to catalyze the synthesis of the RNA strand, researchers explain.
Authors of a March article in the Journal of Medical Virology conclude that "Theaflavin could be used as a lead compound for developing a SARS‐CoV‐2 inhibitor that targets RdRp. However, the exact in vivo effect is still unclear, and further research is needed to confirm the mechanism whereby theaflavin target SARS‐CoV‐2."
In Taiwan, a team of researchers recently concluded an investigation of 720 compounds listed in the Natural Product Libraries for anti-COVID-19 efficacy. The list was narrowed to 10 compounds and mixtures that had strong potential for anti-COVID-19 efficacy, according to Dr. Bashar Khiatah.
“The compounds that have been found to have an anti-COVID 19 effect are the polyphenols that are found in teas,” writes Amylee Amos, MS, RDN. These are found in black tea, green tea, oolong tea, and puer. The most promising is theaflavin-3,3′ -digallate (TF3), which is converted from catechins during fermentation.
The Tea Research Institute of Sri Lanka (TRI) is exploring whether theaflavins reduce the rate of viral spread, according to the Institute’s website.
“The broad-spectrum of antiviral activity of compounds found in tea against several influenza viruses suggest that tea might be a promising source of antiviral compounds in the prevention and therapeutic aspects against influenza and that group of viruses; however, information on antiviral activity of back tea against SARS-CoV-2 is not yet clear. The fact that theaflavin has emerged as a promising candidate to inhibit RdRp activity in the SARS-CoV-2 augers well in the search for a therapeutic agent against COVID-19 pandemic,” according to the website.
As early as 1998, scientists demonstrated tea theaflavins completely neutralized bovine coronavirus and rotavirus infections. In 2005, Chinese researchers showed that black tea significantly inhibited chymotrypsin-like protease activity essential to virus reproduction. Recent in-vitro studies found TF3 completely inhibited COVID virus replication in cell cultures. The United Planters’ Association of South India (UPASI) Tea Research Institute in Coonoor and the Indian Council of Medical Research (ICMR) announced that it would study theaflavins' antiviral properties.Clinical studies in humans are essential before researchers prove the antiviral properties of tea among those suffering from COVID-19.