Against the novel coronavirus it is important to follow the rules of hygiene and social distancing, but it is also essential to strengthen the immune system and put the body in the best conditions to face any external threat. Diet and lifestyle have, for this purpose, a central role as they can help fight chronic inflammations that weaken the immune system, but they can also provide some substances that have been shown to inhibit viruses. This is the case with green tea and black tea polyphenols, as reported in a very recent scientific research published in the journal Phytomedicine by an Indian team (Mhatre et al, Phytomedicine, 2020).
Epigallocatechin gallate is one of the most potent polyphenols of Camellia sinensis, the tea plant. In particular, it is one of the most abundant antioxidants in green tea. Epigallocatechin gallate has shown anticancer, antibacterial, antioxidant, anti-inflammatory and, and this has drawn the attention of researchers for the fight against coronavirus, antiviral properties. In particular, epigallocatechin gallate, or EGCG, has been shown to counteract the hepatitis C virus by inhibiting the entry of the virus into liver cells. Not only that, EGCG has also proved useful in inhibiting influenza A and B, the multiplication of the Ebola virus and of other infections such as Zika virus, Dengue and West Nile virus. Theaflavins are another class of polyphenols very abundant in black tea and characterized by an antitumor, antioxidant, antibacterial, anti-inflammatory and antiviral action. In fact, they have been shown to inhibit influenza A and B and viruses of the coronavirus type. Therefore, given these antiviral properties, scientists wondered if EGCG and theaflavins could also be useful in countering the novel coronavirus. What emerged from computer simulations is that both of these substances have proven effective in binding and inhibiting an enzyme, called 3CLpro, which is essential for the replication of the novel coronavirus and to ensure its life cycle. Not only that, theaflavins have been shown to inhibit, more than all the other natural compounds tested, the enzyme RdRp, which plays a crucial role in the replication and transcription of the virus, and to act as a preventive agent by binding to the ACE2 receptor, used by the novel coronavirus to enter the cells of the body. Finally, EGCG has been shown to inhibit the action of other structural proteins of the novel coronavirus responsible for its vital functions. The inhibition of these proteins is considered to be a preventive action against the spread of the infection.
Therefore, both EGCG and theoflavine showed antiviral properties, both for preventive and therapeutic purposes. However, no studies have yet been carried out on a possible use of these substances on humans in order to combat the novel coronavirus. In fact, bioavailability, action, required quantity and any side effects must be evaluated. While waiting for these studies to be performed, the same authors of the study recommend introducing EGCG and theaflavins into a varied and balanced diet, supplying them with food, in this case, with a nice cup of green tea and black tea.