Persimmon-Derived Tannin: A Promising Antiviral Agent against SARS-CoV-2 Delta Variant

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The ongoing COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to pose significant challenges to public health worldwide.

The emergence of new variants of the virus has raised concerns about the efficacy of existing treatments and preventive measures. In this context, a groundbreaking study has shed light on the potential of persimmon-derived tannin as an effective and versatile antiviral agent against SARS-CoV-2, particularly the highly transmissible Delta variant.

This article provides a comprehensive overview of the research findings, highlighting the antiviral mechanisms, clinical implications, and potential applications of persimmon-derived tannin in the fight against COVID-19.

A Game-Changing Antiviral Effect

The research revealed that persimmon-derived tannin exhibits a remarkable in vitro antiviral effect against the Delta variant of SARS-CoV-2.

This variant, known for its increased severity and transmissibility, has challenged existing preventive measures and therapeutics. However, persimmon-derived tannin emerged as a promising candidate capable of neutralizing the virus regardless of its variant type.

The antiviral effect demonstrated was dose- and time-dependent, mirroring previous findings with non-variant and Alpha-variant SARS-CoV-2 strains [10]. Notably, this sets persimmon-derived tannin apart from vaccines and neutralizing antibody therapy, which have shown reduced effectiveness against emerging variants [17,18].

Understanding the Antiviral Mechanism

The researchers explored the mechanism behind the antiviral action of persimmon tannin. Their previous work revealed that persimmon tannin adheres directly to the SARS-CoV-2 virus, resulting in substantial aggregation due to its strong protein-binding ability [10].

This interaction effectively covers the virus and compromises its infectivity. Crucially, this mechanism seems to be unaffected by the virus variant, providing an advantage over other antiviral strategies that may be compromised by new SARS-CoV-2 variants.

Furthermore, other tannins, such as Pentarlandir ultrapure and potent tannic acid (UPPTA), have been reported to prevent SARS-CoV-2 replication in VeroE6 cells by acting on the 3-chymotrypsin-like protease (3CLpro) and distributed in the lungs, the primary site of SARS-CoV-2 infection [19].

A clinical study using a tannin-based supplement showed a reduction in the inflammatory state and microbiota modulation, indicating that tannins may also have broader effects on inflammatory processes [20]. This suggests the potential for persimmon-derived tannin to exert not only antiviral but also anti-inflammatory effects in COVID-19 patients.

Persimmon-Derived Tannin in Clinical Applications

The researchers conducted a clinical examination where human saliva obtained from a volunteer while consuming tannin-containing hard candy was found to inactivate SARS-CoV-2. Furthermore, administering tannin-containing candy to patients with COVID-19 caused by the Delta variant led to a significant reduction in viral load in their saliva.

This finding is significant because saliva is an important location of virus infection, and it plays a role in the transmission of COVID-19 in both symptomatic and asymptomatic patients. Saliva droplets generated during everyday activities, such as talking and dining, can contribute to virus transmission, making the reduction of viral load in saliva an essential measure to curb the spread of the disease.

Persimmon-Derived Tannin: A Simple and Effective Prophylaxis Method

The researchers utilized a hard candy to deliver persimmon-derived tannin into the mouth, with a concentration of 2% being determined from previous reports to effectively prevent severe COVID-19 pneumonia in an in vivo hamster model. Hard candy allows the tannin to remain in the mouth for an extended period, maximizing its antiviral efficacy. The ease of use, safety, and cost-effectiveness of this method make persimmon-derived tannin-containing candy a potential candidate for widespread COVID-19 prophylaxis.

Limitations and Future Directions

While the research presents promising results, there are several limitations that need to be addressed. The study did not assess the exact tannin concentration attained in saliva during candy consumption, and further investigations are required to quantify the amount of tannin in saliva accurately. Additionally, the limited number of patients with the Delta variant in the clinical examination warrants further research with a larger sample size to validate the findings. Moreover, considering the open-label nature of the study and the order of candy intake, future studies should incorporate randomized, double-blind designs to eliminate potential biases.

Conclusion

The groundbreaking research on persimmon-derived tannin as an antiviral agent against the Delta variant of SARS-CoV-2 presents a promising avenue for COVID-19 prevention and treatment. The dose- and time-dependent inactivation of the virus and the ability to reduce viral load in saliva hold great potential for curbing COVID-19 transmission.

Moreover, the unique mechanism of action unaffected by virus variants and the potential anti-inflammatory effects of tannins further underscore their significance. As the world battles the ongoing pandemic and prepares for potential future variants, persimmon-derived tannin emerges as a simple, safe, and effective prophylactic measure with the potential to make a substantial impact on public health. However, further research is warranted to address the limitations and fully elucidate the therapeutic potential of persimmon-derived tannin in the fight against COVID-19.


reference link : https://www.mdpi.com/1999-4915/15/8/1636

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