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. 2024 Jun;16(2):159-170.
doi: 10.1007/s12560-023-09581-0. Epub 2024 Jan 31.

Screening Commercial Tea for Rapid Inactivation of Infectious SARS-CoV-2 in Saliva

Julianna N Morris  1 , Malak A Esseili  2
Affiliations

Screening Commercial Tea for Rapid Inactivation of Infectious SARS-CoV-2 in Saliva

Julianna N Morris et al. Food Environ Virol. 2024 Jun.

Abstract

SARS-CoV-2 infects the oral mucosa and is shed in salivary fluids. Traditionally, tea has been used by various cultures to treat respiratory ailments. The objective of this study was to identify commercially available teas that can rapidly inactivate infectious SARS-CoV-2 in saliva. Initially, tea (n = 24) was prepared as 40 mg/mL infusions and incubated with SARS-CoV-2 resuspended in water, for 5 min at 37 °C. Then, five teas that showed >3 log reduction in virus infectivity were further investigated at 40 and 10 mg/mL infusions for 60 and 10 s contact time with SARS-CoV-2 resuspended in saliva. Tea polyphenols were measured using the Folin-Ciocalteu assay. SARS-CoV-2 infectivity was quantified on Vero-E6 cell line using TCID50 assay. At 10 mg/mL infusion, black tea showed the highest reduction (3 log, i.e., 99.9%) of infectious SARS-CoV-2 within 10 s. Green, mint medley, eucalyptus-mint, and raspberry zinger teas showed similar inactivation of SARS-CoV-2 (1.5-2 log, i.e., 96-99% reduction). At 40 mg/mL infusions, all five teas showed >3 log reduction in virus infectivity within 10 s. Tea polyphenol but not pH was significantly correlated to virus reduction. Time-of-addition assay revealed that the five teas displayed preventive effects (0.5-1 log, i.e., 68-90% reduction) against SARS-CoV-2 infection of Vero-E6 cells as well as during post-virus infection (1.2-1.9 log, i.e., 94-98%). However, the highest inhibitory effect was observed when the teas were added at the time of virus infection (2-3 log, i.e., 99-99.9%). Our results provide insights into a rapid at-home intervention (tea drinking or gargling) to reduce infectious SARS-CoV-2 load in the oral cavity which might also mitigate infection of the oral mucosa.

Keywords: Black tea; Eucalyptus; Green tea; Mint; Polyphenols; Raspberry; SARS-CoV-2.

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References

    1. Arora, I., White, S., & Mathews, R. (2023). Global dietary and herbal supplement use during COVID-19: A scoping review. Nutrients, 15, 771.
    1. CDC. (2022). Symptoms of COVID-19. https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/symptoms.html
    1. Chou, O., Juang, Y. P., Chao, T. L., Tsai, S. F., Chiu, P. F., Chiou, C. T., Tsai, K. C., Chang, S. Y., Liang, P. H., & Wong, C. H. (2023). Isolation of anti-SARS-CoV-2 natural products extracted from Mentha canadensis and the semi-synthesis of antiviral derivatives. Journal of Natural Products, 86, 1428–1436. - DOI
    1. D’Auria, J. C., Cohen, S. P., Leung, J., Glockzin, K., Glockzin, K. M., Gervay-Hague, J., Zhang, D., & Meinhardt, L. W. (2022). United States tea: A synopsis of ongoing tea research and solutions to United States tea production issues. Frontiers in Plant Science, 13, 934651. - DOI
    1. Ding, S., Lee, J. S., Mohamed, M. A., & Ng, B. F. (2022). Infection risk of SARS-CoV-2 in a dining setting: Deposited droplets and aerosols. Building and Environment, 213, 108888. - DOI

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