&amp;lt;i&amp;gt;Morinda citrifolia&amp;lt;/i&amp;gt; (Noni) Fruit Juice Inhibits SARS-CoV-2 Spike Protein Binding of Angiotensin-Converting Enzyme 2 (ACE2)

Brett J West,Shixin Deng

doi:10.4236/jbm.2021.911005

Abstract

COVID-19 is a global pandemic that has claimed millions of lives. This disease is caused by a coronavirus, SARS-CoV-2, which requires the binding of its spike protein to angiotensin-converting enzyme 2 (ACE2) for infection of the host cell. Morinda citrifolia (noni) fruit juice has antiviral activity that involves enhancement of immune system function. SARS-CoV-2 spike-ACE2 interaction experiments were carried out to further investigate the antiviral properties of noni juice and its major iridoids. Noni juice inhibited binding by approximately 69%. Scandoside was the most active of the three iridoids evaluated, reducing average spike protein-ACE2 interaction by 79.25%. The iridoids worked synergistically towards inhibiting spike protein binding when assayed together, improving activity by more than 22% above the expected level. But the modest activity of the most abundant iridoid, deacetylasperulosidic acid, indicates that other phytochemicals (i.e. scopoletin, quercetin, rutin and kaempferol) are also involved. Our results suggest that the presence of several biological active phytochemicals in noni juice enhances resistance to SARS-CoV-2 by interfering with its ability to bind ACE2. This is a new and significant anti-viral mechanism of noni juice that does not directly involve its immunomodulatory properties.

Highlights

IntroductionCoronaviruses are a group of viruses known for the characteristic glycoprotein
Noni juice exhibited significant anti-spike protein potential by reducing average spike protein-angiotensin-converting enzyme 2 (ACE2) binding by 69.14%
Noni juice reduced the ability of SARS-CoV-2 to bind ACE2 in vitro

Summary

Introduction

Coronaviruses are a group of viruses known for the characteristic glycoprotein. First isolated in the 1960s, coronaviruses were originally associated with nasopharyngitis, or the common cold [2]. These RNA viruses have since been found to be responsible for producing much more severe symptoms in the upper respiratory tract as well as adversely affecting other organs throughout the body, often with lethal outcomes [3]. The recent coronavirus disease 2019 (COVID-19) pandemic was caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), resulting in more than 4.18 million deaths worldwide as of July 2021 [4] [5]

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