GUWAHATI, May 16 - There is documented evidence on immunity and antiviral activity of black tea and its bioactives, and as such regular consumption of black tea could very well fit in as a component of a healthy diet for boosting immunity, which is considered essential in this time of global pandemic created by COVID-19, a publication by Tocklai Tea Research Institute has said.
The theaflavins present in black tea have been reported to inhibit HIV, hepatitis C and influenza viruses. A recent study in China suggested that theaflavins, present in abundance in the black tea of Assam, could be used as a lead compound to inhibit the SARS-CoV2 virus. Further, in another study in Taiwan, black tea extracts were demonstrated to have inhibitory activities against 3C-like protease (3CLPro) enzyme of another SARS virus, the report by Dr AK Barooah, director of Tea Research Association, stated.
Elaborating, the Tocklai publication referred to a recent study published in the �Journal of Medical Virology�, where 83 compounds used in Chinese medicine system were screened for their potential efficacy against SARS-CoV-2 by assessing their binding efficiency onto this RNA dependent RNA polymerase (RdRp) of the COVID-19 virus.
�This virtual screening to test the efficacy of the compounds in this bioinformatics study revealed that out of the 83 compounds screened, theaflavin was the best compound on the basis of idock score (prediction of binding affinity), hydrophobic interactions and additional hydrogen bonds between theaflavin and amino acid near the active site of RdRp. This was further confirmed by lower binding energy when it docks the catalytic pocket of SARS-CoV-2 RdRp. These finding suggested that theaflavins could be used as a lead compound for developing a SARS-CoV-2 inhibitor that targets the RdRp. Theaflavins are present in black tea and the highest theaflavin contents are present in the black teas of Assam,� Dr Barooah stated.
The report further stated that though further in vivo, animal and clinical trials would be required to carry forward this research finding, an earlier study from Taiwan has convincingly demonstrated the inhibition of SARS-CoV 3C-like protease activity by Theaflavin-3, 3�-digallate (TF3) published in the journal �Evidence based Complementary and Alternative Medicine�.
The authors have reported that the extracts from Puer and Black tea were more potent than the green or oolong tea extracts in their inhibitory activities against a chymotrypsin-like (3CLPro) protease.
In this study, 3CL protease was a target and the virus of interest was SARS-CoV (2002 epidemic). This study also used a docking approach to screen out the best inhibitory compounds using a natural product library consisting of 720 compounds. Two compounds, tannic acid and TF2b (Theaflavin 3-gallate) were found to be active against 3CL Protease. The authors further examined the inhibition of activity by various tea extracts and several well known pure ingredients present in teas. The water extracts of TF2b (theaflavin-3-gallate), TF3 (theaflavin diggallate) and tannic acid were found to be the best effective 3CLPro inhibitors with inhibitory concentration (IC50) of less than 10 �M. The results from this study showed that Puer and Black tea extracts were more potent than the green or oolong tea extracts in inhibitory activities against 3C-like protease (3CLPro) of severe acute respiratory syndrome coronavirus (SARS-CoV).
�Given the available evidence of antiviral activity of black tea and its theaflavins against the SARS-CoV coronavirus and the recent demonstration of the binding efficiency of theaflavins onto the RNA dependent RNA polymerase (RdRp) of the COVID-19 virus, the black tea could very well fit in as a component of a healthy diet for boosting immunity which is considered essential in this critical time of Global pandemic created by COVID-19,� Dr Barooah added.
Despite being the world�s most popular beverage, the health benefits associated with tea are quite often ignored. While several studies have established the beneficial properties of green tea, the efficacy of the bioactive compounds present in black tea has been the subject of several recent studies.
Extracts of black tea have been found effective in combating inflammatory diseases, cancers and neurological disorders while being efficient in cardiovascular disease prevention. Black tea consumption has also been associated with weight loss and reduction in obesity. L-theanine, the most predominant amino acid present in tea, boosts immunity by fighting infection by bacteria, viruses and fungi.