Researchers evaluated the effectiveness of tea and its catechins in inactivating the Omicron sub-variant of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Investigating the ability of tea’s catechins to suppress Omicron sub-variants was the study’s main objective.
Additionally, they investigated the potential of using saliva from individuals who consumed candies containing black or green tea to deactivate the Omicron BA.1 subvariant in vitro.
They treated Omicron suspensions with freshly brewed black or green tea, made by combining green Matcha tea powder or by submerging tea leaves in warm water at 90% concentration, to evaluate the effect of tea on Omicron sub-variants.
Does Matcha Tea Really Deactivate The Virus
After exposing Omicron sub-variants to various tea catechins for 10 seconds, 50% tissue culture infectious dose (TCID50) tests were conducted to gauge their infectious potential.
The researchers also provided theaflavins (TF, TF3’G, TF3G, and TFDG) in quantities comparable to those present in black tea, and they also examined the effects of various doses of EGCG and TFDG on Omicron sub-variants. Additionally, they looked into the effects of various TFDG concentrations on the Omicron subvariant’s inactivation.
Cells were pretreated with EGCG before being infected with Omicron BA.1 and treated with distilled water (DW) to evaluate EGCG’s antiviral effects on the cells or the virus. Neutralization studies were performed to determine whether EGCG, GCG, and TFDG hindered interaction with the BA.1 RBD and ACE2.
Additionally, molecular docking simulations were conducted to investigate how EGCG and TFDG hindered the physical link between ACE2 and Omicron S RBD. Last but not least, the scientists examined whether chewing sweets containing green or black tea could result in saliva that could inactivate SARS-CoV-2.
Omicron sub-variants were successfully inactivated by green tea, matcha, and black tea. The Omicron BA.1 and XE sub-variants infectivity was greatly lowered by EGCG and TFDG, but the BA.2.75 sub-variants were less affected. Additionally, the interaction between BA.1 RBD and ACE2 was lessened by EGCG and TFDG.
The EGCG/TFDG binding to the RBDs was modified by the RBD mutations N460K, G446S, and F490S. Treatment with any tea sample decreased BA.1’s titer to less than 1/100 of the control virus treated with DW, and other sub-variants showed comparable results.
Green tea significantly decreased the infectivity of the variants BA.1, BA.5, and BQ.1.1 but had less impact on BA.2.75. GCG and EGCG decreased BA.1, XE, and BA.2.75 sub-variant titers to less than 1% and 1/10, respectively, with EGCG extracts exhibiting antiviral properties akin to green tea ones.
The study indicated that the N460K mutation is linked to EGCG’s viral inactivation, and the G446S replacement was present in BA.1, BA.2.75, and OmicronXBB.1 but not inBA.1. TFDG’s interaction with Y449, Y453, F486, Q493R, Q498R, and N501Y inBA.2 andBA.2.75 intercepted hydrogen bonds with ACE2’s H34, E35, D38, Y41, Q42, L79, M82, Y83, and K357.
The similar interaction disrupted the hydrogen bonds between the Y449, Q493R, and Q498R of BA.2.75 and the H34, E35, D38, Y41, and Q42 of ACE2. Participants ate sweets containing green or black tea, and their saliva significantly reduced the infectivity of BA.1 in vitro.
This study proved that drinking green, Matcha, and black tea can efficiently inactivate Omicron sub-variants. The binding of EGCG/TFDG to the RBDs and the sensitivity of each Omicron sub-variant to EGCG/TFDG are significantly influenced by specific amino acid alterations in the RBDs. These results shed light on the possible application of these substances in the fight against mutant viruses that may emerge and cause pandemics.