The natural tannins oligomeric proanthocyanidins and punicalagin are potent inhibitors of infection by SARS-CoV-2

Abstract

The Coronavirus Disease 2019 (COVID-19) pandemic continues to infect people worldwide. While the vaccinated population has been increasing, the rising breakthrough infection persists in the vaccinated population. For living with the virus, the dietary guidelines to prevent virus infection are worthy of and timely to develop further. Tannic acid has been demonstrated to be an effective inhibitor of coronavirus and is under clinical trial. Here we found that two other members of the tannins family, oligomeric proanthocyanidins (OPCs) and punicalagin, are also potent inhibitors against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection with different mechanisms. OPCs and punicalagin showed inhibitory activity against omicron variants of SARS-CoV-2 infection. The water extractant of the grape seed was rich in OPCs and also exhibited the strongest inhibitory activities for viral entry of wild-type and other variants in vitro. Moreover, we evaluated the inhibitory activity of grape seed extractants (GSE) supplementation against SARS-CoV-2 viral entry in vivo and observed that serum samples from the healthy human subjects had suppressive activity against different variants of SARS-CoV-2 Vpp infection after taking GSE capsules. Our results suggest that natural tannins acted as potent inhibitors against SARS-CoV-2 infection, and GSE supplementation could serve as healthy food for infection prevention.

Herbal Compounds Dauricine and Isoliensinine Impede SARS-CoV-2 Viral Entry

“…Compounds with a toxicity rate of over 50% were eliminated, while others were subjected to infection using a VPP assay to assess their ability to reduce infection rates (Figure 2B). To further examine the efficiency of our VPP assay, we also used well-known inhibitors, hydroxychloroquine (HCQ) and oligomeric proanthocyanidins (OPCs), as positive controls (Supplementary Figure S1A) [31][32][33]. Several studies have reported that high expression levels of ACE2 are correlated with severe infection and COVID-19-related complications [34,35].…”

“…The data revealed that neither Dauricine nor Isoliensinine possessed any notable effect on TMPRSS2 protease activity (Figure 6C,D) when TMPRSS2 was overexpressed in 293T cells (Supplementary Figure S3B). To further examine the effects of Dauricine and Isoliensinine on TMPRSS2 protease activity, we also used well-known TMPRSS2 inhibitors, tannic acid and oligomeric proanthocyanidins (OPCs), as positive controls (Supplementary Figure S3A) [32,40]. To further analyze the effects of Dauricine and Isoliensinine on infection rates in the presence or absence of TMPRSS2, human TMPRSS2 and a control vector were ectopically expressed in 293T-ACE2 and VeroE6 cell lines (Supplementary Figure S3C,D).…”

Emerging Therapeutic Potential of Polyphenols from Geranium sanguineum L. in Viral Infections, Including SARS-CoV-2

“…-based enzyme activity assay of M pro ; Surface plasmon resonance analysis; Molecular docking; Vpp pseudoviral particle infection assay Dual inhibition of TMPRSS2 and M pro /3CL pro with subsequent SARS-CoV-2 activity inhibition [94,95] Docking characterization and in vitro Inhibitory activity Dual inhibition of TMPRSS2 and M pro /3CL pro with suppression of cellular entry of the virus [94]High potential for SARS-CoV-2 inhibition[96][97][98][99] …”