Significative Inactivation of SARS-CoV-2 3CL- Protease by Camellia sinensis Galloylated theaflavins: Processing conditions to maximize TF-3,3’-DG content Volume 5 - Issue 1

Lisete Paiva^1,2, Catarina Rato^2,3 and José Baptista^1,2,*

• ¹Department of Science Physics, Chemistry and Engineering (DCFQE) and Institute of Agricultural and Environmental Research and Technology (IITAA), University of Azores, Portugal
• ²Faculty of Science and Technology, University of Azores, Delgada, São Miguel, Portugal
• ³Faculty of Medicine, University of Coimbra, Portugal

Received: July 04,2022;   Published: July 08, 2022

Corresponding author: José Baptista, Department of Science Physics, Chemistry and Engineering (DCFQE) and Institute of Agricultural and Environmental Research and Technology (IITAA), University of Azores, 9500-321 Ponta Delgada, São Miguel, Portugal

DOI: 10.32474/CDVS.2022.05.000202

Abstract PDF

Since the last decade of the 19th century, the Camellia sinensis tea plant is commercially produced in one unique place in Europe, the volcanic São Miguel Island of the Azores Archipelago (Portugal) [1,2]. The molecular constituents of C. sinensis, in particular the galloylated theaflavins, mainly theaflavin-3,3’-di-O-gallate (TF-3,3’-DG), have been reported to inhibit SARS-CoV-2 3-chymotrypsin-like protease (3CLpro), a crucial enzyme required for the cleavage of its polyproteins (1a and 1ab) to produce vital individual functional proteins for viral cell replication [3]. According to Ohgitani [4] the virus treated with galloylated theaflavins, particularly TF-3,3’-DG, at 100 μM showed less than 1/10.000 infectivity compared to untreated virus. The TF-3,3’-DG content increased 50.91% with increased fermentation time from 1 to 3 hrs at room temperature (RT) and increased 41.26% at 35 °C of fermentation temperature. Furthermore, TF-3,3’-DG increased 29.40% with increasing temperature from RT to 70 °C in short extraction time (1:30 hrs) and oppositely decreased 18.44% with increasing temperature from RT to 70 °C in long extraction time (16:00 hrs). Taking all of the in vitro reported studies by several research teams and the in vivo results comparing the COVID-19 infections (mortality per million of population) in high tea consumption (4.28%) as compared with low tea consumption countries [5], the aim of this study was to investigate the steps of tea manufacturing conditions which lead to maximum TF-3,3’-DG content and, given its potential impact as an inhibitor of the 3CLpro enzyme, to create a novel antiviral Azorean black tea.

The Table 1 clearly shows a low percentage (average of 95.7% lower) of infections by SARS‐CoV‐2 (COVID-19 mortality per million population) in countries with a higher consumption of C. sinensis tea as compared to countries with low tea consumption. According to Storozhuk [6], C. sinensis tea constituents could reduce overall risks related to COVID‐19. This implies that tea theaflavins may be effective in the prevention/treatment of COVID‐19 or the amelioration of its severity. It is well known that theaflavins contents in different tea samples changed according to different plucking seasons and are affected by many factors, such as plant variety, origin of tea production, agronomic management, climate, as well as by the tea processing and storage conditions. The Table 2 shows the variability of the TF-3,3’-DG content in different processing conditions. The TF-3,3’-DG content increased 50.91% with increased fermentation time from 1 to 3 hrs at room temperature (RT) and increased 41.26% at 35 °C of fermentation temperature. Furthermore, TF-3,3’-DG increased from 3.98 to 5.15 mg/g DW with increasing temperature from RT to 70 °C in short extraction time (1:30 hrs) and oppositely decreased from 5.64 to 4.60 mg/g DW with increasing temperature from RT to 70 °C in long extraction time (16:00 hrs). On the other hand, the value of TF-3,3’- DG change in different parts of the tea plant showed higher content (three times more) in bud plus 1st and 2nd leaves as compared to 3rd plus 4th leaves (data not shown).

Table 1: Countries with “low” and “high” (above 150 g per/capita) tea consumption relatively to the total COVID-19 mortality per millions of people and percentage of COVID-19 mortality per total infections in different countries.

^aData from Johns Hopkins Coronavirus Resource Center on July 2, 2022; b Higher ratio means low support by Health Care Institutions for COVID-19 patients.

Table 2: Theaflavins content from Camellia sinensis in different processing conditions (mg/g DW)^a .

^aValues are mean ± SD (n = 3); DW, dry weight; RT, room temperature; TF, theaflavin; TF-3-G, theaflavin-3-gallate; TF-3’-G, theaflavin- 3’-gallate; TF-3,3’-DG, theaflavin-3,3´-di-gallate.

The TF‐3,3′‐DG content in Azorean black tea was affected by the different processing conditions. Countries with higher C. sinensis tea consumption presented lower SARS-CoV-2 infectivity. The best extraction time for all theaflavins is 16 hrs at room temperature and for fermentation time the higher values was observed at 3 hrs at RT as compared with 35 °C. This study revealed the possibility to create a novel Azorean antiviral tea, investigating the black tea processing conditions, to maximize the TF-3,3’-DG content as an inhibitor of 3CLpro enzyme and, consequently, reducing the SARSCoV- 2 infectivity as already reported by several research teams.

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