Pomegranate extract can inhibit the virus strain that causes coronavirus, say Experts

Scientists in Italy have conducted a research experiment manifesting the potential antiviral effects of pomegranate extract against severe acute respiratory syndrome SAR-CoV-2, the strain causing coronavirus disease 2019.

The team determined that constituents in extracts from pomegranate peels inhibited the binding of SARS-CoV-2 to the human host cell receptor angiotensin-converting enzyme 2 (ACE2) in vitro as PPE compounds also inhibited the SARS-CoV-2 main protease 3CL pro activity required to replicate and survive within the host cell.

A preliminary version of the paper can be viewed on bioRxiv while the article undergoes peer review.

One of the most severe pandemics in human history

Since its identification last December, the corona virus outbreak has led to one of the most severe pandemics in human history, with 69.58 million infections and 1.58 million deaths as of December 11.

The infection creates a spectrum of ailments accompanied by mild symptoms to severe ones leading to multiple organ damage. SARS-CoV-2 mainly targets tissues that express high levels of ACE2 – the human receptor that the virus uses to gain host cell entry. Since the airways express high levels of ACE2, individuals who experience severe disease often develop viral pneumonia or acute respiratory distress syndrome, which can lead to respiratory failure. Significant efforts have been exerted to develop therapeutic strategies leading to the development of a handful of vaccines, including Pfizer, AstraZeneca, Moderna, Sputnik V and CoronaVax. The main viral structure SARS-CoV-2 utilizes to reach host cells is the surface Spike protein, which attaches to the ACE2 receptor via its receptor-binding domain.

Can plants compounds play a role in the inhibition of the disease? 

Plant extracts contain plenty of bioactive molecules such as polyphenols that play essential roles in plant survival by guarding against pathogens such as bacteria, viruses, and fungi. Various previous studies manifested the antiviral potential of some polyphenol types against a spectrum of viral infections, including influenza and Epstein-Barr virus. Plant extracts' potential antiviral activity against SARS-CoV-2 infection also implied that plant polyphenols could be potential drug candidates for Covid-19 treatments.

Numerous molecular docking studies showed that polyphenols such as curcumin, kaempferol, catechin, naringenin, and quercetin may inhibit the activity and replication of SARS-CoV-2. "One study also suggested that the binding of two polyphenols, punicalagin, and theaflavin, to the Spike protein, could be exploited as a strategy to inhibit the virus entry into human cells," write Apone and colleagues. Furthermore, several studies investigating the antiviral effects of PPE on influenza and the herpes simplex virus have led researchers to hypothesize that these extracts may contain effective components against SARS-CoV-2.

What did the researchers examine?

Apone and team used in vitro techniques to evaluate the potential antiviral activity of PPE against SARS-CoV-2. Representing 38.9% of all the polyphenols, punicalagin was the most abundant polyphenol in the PPE, and it was followed by pedunculagin anomers (16.7%) and punicalin anomers (13.2%). Using an inhibitor screening kit, the researchers showed that three PPE concentrations, ranging from 0.04 mg/mL to 1 mg/mL, inhibited the interaction between Spike and ACE2 by up to 74% in a dose-dependent manner. Further analysis of PPE's components revealed that punicalagin was the most effective compound at disrupting this interaction, inhibiting 49% of the Spike–ACE2 binding. This was followed by ellagic acid, which inhibited 36% of the interaction.

With Punicalagin appearing as the most efficient compound, the research people discovered that incubation of the viral main protease 3CL pro with PPE inhibited the enzyme activity by up to 80%.

What are the study indications?

The researchers state the findings suggest that PPE may execute multiple biological roles in decreasing the ability of SARS-CoV-2 to affect host cells. "The study here presented paves the way for a deeper investigation on the activity of pomegranate peel polyphenols in preventing SARS-CoV-2 infection in vivo, and it may also promote new ideas on how to reuse agroindustry byproducts for medical and health care applications," concludes the team.