Extracts from Two Wild Plants Can Prevent COVID-19

An Emory University study discovered that extracts from two common wild plants decrease the capacity of the virus that causes COVID-19 to infect live cells. The findings were published in Scientific Reports as the first large screening of botanical extracts for effectiveness against the SARS-CoV-2 virus.

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Plant Extracts Prevent COVID-19

Extracts from the blooms of tall goldenrod (Solidago altissima) and the rhizomes of eagle fern (Pteridium aquilinum) each prevented SARS-CoV-2 from entering human cells in laboratory dish experiments. The active chemicals are only found in trace amounts in plants. People attempting to treat themselves with them would be futile and potentially hazardous, according to the study. They caution that the eagle fern is known to be harmful.

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Testing the Long-Term Safety And Efficacy of Extracts

“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,” says Cassandra Quave, senior author of the study and associate professor at Emory School of Medicine’s Department of Dermatology and the Center for the Study of Human Health. “Once we have isolated the active ingredients, we plan to further test for their safety and their long-range potential as medicines against COVID-19.”

Quave is an ethnobotanist who studies how traditional peoples used plants for healing to find viable new drug prospects. Her lab is in charge of the Quave Natural Product Library, which houses thousands of botanical and fungal natural products isolated from plants collected around the world.

The latest paper's primary author is Caitlin Risener, a Ph.D. candidate in Emory's Molecular and Systems Pharmacology graduate program and the Center for the Study of Human Health.

Previously, the Quave lab focused on plants that traditional people had used to treat skin inflammation to find promising compounds for the treatment of drug-resistant bacterial infections.

Because COVID-19 is a new disease, the researchers used a comprehensive approach. They developed a method for speedily testing over 1,800 extracts and 18 compounds from the Quave Natural Product Library for SARS-CoV-2 activity.

“We’ve shown that our natural products library is a powerful tool to help search for potential therapeutics for an emerging disease,” Risener says. “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.”

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Plant Extract is Effective Against All the Strains of COVID-19 Virus

SARS-CoV-2 is an RNA virus with a spike protein that can connect to a protein on host cells called ACE2. "The viral spike protein acts much like a key entering a lock, allowing the virus to break into and infect a cell," Quave adds.

The researchers designed studies using SARS-CoV-2 virus-like particles, or VLPs, and cells modified to overexpress ACE2 on their surface. The VLPs were stripped of the genetic material required to infect COVID-19. Instead, if a VLP was able to connect to an ACE2 protein and enter a cell, it was programmed to hijack the cell's machinery, causing a fluorescent green protein to be activated.

Before injecting the virus particles, a plant extract was applied to the cells in a petri dish. They could rapidly tell whether the viral particles had entered the cells and activated the green protein by placing a fluorescent light on the dish.

The researchers found a few hits for extracts that protect against the viral entrance and then focused on the ones with the highest activity: tall goldenrod and eagle fern. Both plant species are native to North America and have long been used for medical purposes by Native Americans.

Additional tests revealed that the plant extracts' protective power was effective against all four SARS-CoV-2 variants: alpha, theta, delta, and gamma.

The Quave lab collaborated with co-author Raymond Schinazi, Emory professor of pediatrics, director of Emory's Division of Laboratory of Biochemical Pharmacology, and co-director of the HIV Cure Scientific Working Group within the NIH-sponsored Emory University Center for AIDS Research, to further test these findings. Schinazi is a world expert in antiviral development, best recognized for his groundbreaking work on breakthrough HIV medications.

Because of the Schinazi lab's superior biosecurity rating, the researchers were able to test the two plant extracts in trials utilizing infectious SARS-CoV-2 virus instead of VLPs. The findings validated the potential of tall goldenrod and eagle fern extracts to block SARS-ability CoV-2's to attach to and infect live cells.

“Our results set the stage for the future use of natural product libraries to find new tools or therapies against infectious diseases," Quave says.

The researchers are now attempting to pinpoint the precise method by which the two plant extracts inhibit ACE2 protein binding.

One of the most enjoyable aspects of the endeavor for Risener was collecting samples of tall goldenrod and eagle ferns herself. The Quave lab, in addition to collecting medicinal plants from throughout the world, does field trips to the forests of the Joseph W. Jones Research Center in South Georgia. The Woodruff Foundation built the institute to help maintain one of the few remains of the once-dominant southern longleaf pine ecosystem.

“It’s awesome to go into nature to identify and dig up plants,” Risener says. “That’s something that few graduate students in pharmacology get to do. I’ll be covered in dirt from head to toe, kneeling on the ground and beaming with excitement and happiness.”

She also helps to prepare plant extracts and mount specimens for the Emory Herbarium. “When you collect a specimen yourself, and dry and preserve the samples, you get a personal connection,” she says. “It’s different from someone just handing you a vial of plant material in a lab and saying, ‘Analyze this.’”

Risener plans to pursue a career in outreach and education for science policy related to natural chemical research after graduation. Some of the more well-known botanical medicines include aspirin (derived from the willow tree), penicillin (derived from fungi), and the cancer treatment Taxol (from the yew tree).

“Plants have such chemical complexity that humans probably couldn’t dream up all the botanical compounds that are waiting to be discovered,” Risener says. “The vast medicinal potential of plants highlights the importance of preserving ecosystems.”

Source-Medindia