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Int J Biol Sci ; 18(12): 4669-4676, 2022.
Article in English | MEDLINE | ID: covidwho-1897097


Tannins are polyphenols enriched in wood, bark, roots, leaves, seeds and fruits of a variety of plants. Over the last two decades, there has been an increasing interest in understanding the biological functions of tannins and their applications as antioxidants, anticancer drugs, and food additives. Since the outbreak of the COVID-19 pandemic, much effort has been devoted to finding an expedient cure. Tannins have been put forward as having possible anti-COVID-19 properties; however, owing to the profuse nature of the structurally diverse derivatives of tannins, the tannin species in the family associated with an indication of anti-COVID-19 have been poorly defined, compounded by frequent terminology misnomers. This article reviews the tannin family in fruits and the current knowledge about the activities of the compounds with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It will aid molecular and cellular biologists in developing natural anti-viral chemicals as means of overcoming the current and future pandemics.

COVID-19 , SARS-CoV-2 , Antiviral Agents/therapeutic use , COVID-19/drug therapy , Humans , Pandemics , Tannins/chemistry , Tannins/pharmacology , Tannins/therapeutic use
Int J Mol Sci ; 23(5)2022 Feb 27.
Article in English | MEDLINE | ID: covidwho-1715407


The overall impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on our society is unprecedented. The identification of small natural ligands that could prevent the entry and/or replication of the coronavirus remains a pertinent approach to fight the coronavirus disease (COVID-19) pandemic. Previously, we showed that the phenolic compounds corilagin and 1,3,6-tri-O-galloyl-ß-D-glucose (TGG) inhibit the interaction between the SARS-CoV-2 spike protein receptor binding domain (RBD) and angiotensin-converting enzyme 2 (ACE2), the SARS-CoV-2 target receptor on the cell membrane of the host organism. Building on these promising results, we now assess the effects of these phenolic ligands on two other crucial targets involved in SARS-CoV-2 cell entry and replication, respectively: transmembrane protease serine 2 (TMPRSS2) and 3-chymotrypsin like protease (3CLpro) inhibitors. Since corilagin, TGG, and tannic acid (TA) share many physicochemical and structural properties, we investigate the binding of TA to these targets. In this work, a combination of experimental methods (biochemical inhibition assays, surface plasmon resonance, and quartz crystal microbalance with dissipation monitoring) confirms the potential role of TA in the prevention of SARS-CoV-2 infectivity through the inhibition of extracellular RBD/ACE2 interactions and TMPRSS2 and 3CLpro activity. Moreover, molecular docking prediction followed by dynamic simulation and molecular mechanics Poisson-Boltzmann surface area (MMPBSA) free energy calculation also shows that TA binds to RBD, TMPRSS2, and 3CLpro with higher affinities than TGG and corilagin. Overall, these results suggest that naturally occurring TA is a promising candidate to prevent and inhibit the infectivity of SARS-CoV-2.

COVID-19/metabolism , Molecular Docking Simulation , SARS-CoV-2/metabolism , Serine Endopeptidases/metabolism , Tannins/pharmacology , Algorithms , Angiotensin-Converting Enzyme 2/metabolism , COVID-19/epidemiology , COVID-19/virology , Coronavirus 3C Proteases , Glucosides/chemistry , Glucosides/metabolism , Glucosides/pharmacology , Humans , Hydrolyzable Tannins/chemistry , Hydrolyzable Tannins/metabolism , Hydrolyzable Tannins/pharmacology , Kinetics , Pandemics/prevention & control , Protein Binding/drug effects , SARS-CoV-2/physiology , Spike Glycoprotein, Coronavirus/metabolism , Surface Plasmon Resonance , Tannins/chemistry , Tannins/metabolism , Virus Internalization/drug effects
Sci Rep ; 11(1): 23695, 2021 12 08.
Article in English | MEDLINE | ID: covidwho-1561520


Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly spread across the world. Inactivating the virus in saliva and the oral cavity represents a reasonable approach to prevent human-to-human transmission because the virus is easily transmitted through oral routes by dispersed saliva. Persimmon-derived tannin is a condensed type of tannin that has strong antioxidant and antimicrobial activity. In this study, we investigated the antiviral effects of persimmon-derived tannin against SARS-CoV-2 in both in vitro and in vivo models. We found that persimmon-derived tannin suppressed SARS-CoV-2 titers measured by plaque assay in vitro in a dose- and time-dependent manner. We then created a Syrian hamster model by inoculating SARS-CoV-2 into hamsters' mouths. Oral administration of persimmon-derived tannin dissolved in carboxymethyl cellulose before virus inoculation dramatically reduced the severity of pneumonia with lower virus titers compared with a control group inoculated with carboxymethyl cellulose alone. In addition, pre-administration of tannin to uninfected hamsters reduced hamster-to-hamster transmission of SARS-CoV-2 from a cohoused, infected donor cage mate. These data suggest that oral administration of persimmon-derived tannin may help reduce the severity of SARS-CoV-2 infection and transmission of the virus.

Antiviral Agents/therapeutic use , COVID-19/drug therapy , Diospyros/chemistry , Tannins/therapeutic use , Administration, Oral , Animals , Antiviral Agents/chemistry , Antiviral Agents/isolation & purification , Antiviral Agents/pharmacology , COVID-19/pathology , COVID-19/transmission , COVID-19/virology , Cricetinae , Diospyros/metabolism , Disease Models, Animal , Interleukin-1beta/genetics , Interleukin-1beta/metabolism , Interleukin-6/genetics , Interleukin-6/metabolism , Lung/pathology , Lung/virology , Male , Mesocricetus , SARS-CoV-2/isolation & purification , SARS-CoV-2/physiology , Severity of Illness Index , Tannins/chemistry , Tannins/isolation & purification , Tannins/pharmacology , Viral Load/drug effects