Wild plant extracts can block Covid-19 infection

A new study led by Emory University has found that two common wild plants can inhibit the activity of the virus causing Covid-19 to infect human cells. Laboratory experiments revealed that extracts from the flowers of tall goldenrod (Solidago altissima) and the rhizomes of the eagle fern (Pteridium aquilinum) efficiently stopped SARS-CoV-2 from entering human cells.

Since the active compounds are only present in small quantities in the plants, it would be ineffective – and even potentially dangerous – for people to attempt to treat themselves with them. 

“It’s very early in the process, but we’re working to identify, isolate and scale up the molecules from the extracts that showed activity against the virus,” said study senior author Cassandra Quave, an associate professor of Dermatology and Human Health at Emory. “Once we have isolated the active ingredients, we plan to further test for their safety and for their long-range potential as medicines against Covid-19.”

By testing over 1,800 extracts and 18 compounds from the Quave Natural Product Library for activity against the new coronavirus, the scientists managed to identify the most promising candidates for potential treatments.

In a first step, they devised experiments with virus-like particles (VLPs) of SARS-CoV-2 and cells programmed to overexpress ACE2 (the receptor on which the coronavirus binds to infiltrate cells) on their surface. The analyses revealed a handful of extracts that stopped viral entry, with those from the tall goldenrod and the eagle fern exhibiting the strongest blocking activity.

Additional experiments using infectious SARS-CoV-2 virus instead of VLPs confirmed these results and showed that the protective power of the plant extracts worked in the case of four Covid variants: Alpha, Beta, Delta, and Gamma.

Further research is needed to determine the precise mechanism which enables these two extracts to block the virus from binding to the ACE2 receptor.

“We’ve shown that our natural products library is a powerful tool to help search for potential therapeutics for an emerging disease,” said study lead author Caitlin Risener, a doctoral student in Molecular and Systems Pharmacology at Emory. “Other researchers can adapt our screening method to search for other novel compounds within plants and fungi that may lead to new drugs to treat a range of pathogens.”

The study is published in the journal Nature Scientific Reports.

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By Andrei Ionescu, Earth.com Staff Writer

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