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This seaweed extract outperforms COVID-19 drug remdesivir in the lab

And it could be used to develop preventive treatments.

This seaweed extract outperforms COVID-19 drug remdesivir in the lab
[Images: dvoriankin/iStock, PhonlamaiPhoto/iStock]
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Remdesivir was the first major pharmaceutical breakthrough of the coronavirus pandemic: Research has found it’s able to help some patients recover faster from severe cases of the illness and may make it more likely that they survive. But a new study suggests that an extract from seaweed may outperform the drug.

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The extract, called RPI-27—found in the same type of seaweed that you might eat in sushi—helps trap the virus before it can infect human cells. Researchers at Rensselaer Polytechnic Institute tested the extract in the cell studies, along with the blood thinner heparin, which has a similar effect.

When someone is infected with SARS-CoV-2, the virus that causes COVID-19, a spike-shaped protein in the virus attaches to a receptor on a human cell and then inserts its genetic material. But if another molecule with the right fit is available to act as a receptor instead of human cells, the virus can attach to it instead, trapping the virus in place as it harmlessly degrades.

“You’ve effectively blocked infection by serving as a decoy,” says Jonathan Dordick, the lead researcher and a professor of chemical and biological engineering at Rensselaer Polytechnic Institute. “Effectively, it interferes with and it pulls away the virus, and therefore the virus can’t bind to the surface of the cell. Once it’s latched on to by these compounds—these seaweed extracts or heparin—it likely decomposes and it would not be effective.”

In cell tests in the lab, RPI-27 was nearly 10 times as active as remdesivir at blocking infection, meaning a much smaller dose was needed to inhibit infection. Heparin was slightly less active than remdesivir but could also be used in treatment. Separate tests showed that the compounds worked without causing any damage to the cells. The researchers are now beginning the next step of animal trials.

But it should be generally safe: “Anytime you eat seaweed in something like sushi, you’re going to be taking in these compounds,” he says. Because only a small concentration is needed, and the compound is found in edible seaweed, a treatment could get FDA approval fairly quickly because the substance is considered GRAS, or generally recognized as safe.

Heparin is usually given through an IV, because it’s used to treat blood clots. But an IV treatment could pose other problems for patients. However, it could also be given through an inhaler directly into the lungs, which Dordick says has been tested and shown to have little to no effect on bleeding. The researchers are now talking to clinical partners about potentially testing a nasal spray using heparin, since it’s thought that COVID-19 infections often begin in the nasal passages.

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“You could dissolve this in saline, just like any other nasal spray,” he says. “You could just take some of that prophylactically several times a day. We would expect that it would bind very well to the virus, essentially inactivating it. And that would be a way that would prevent it from ultimately making it down into the lungs.” The seaweed extract could potentially be used in a similar way. Like remdesivir, which had already progressed through several trials for Ebola before pivoting to COVID-19, it’s helpful that heparin is already an approved drug. “These are the fastest ways to get things to the patient,” he says.


Correction: Due to an editing error, this story previously indicated that RPI-27 would bind to a human cell in place of the SARS-CoV-2. Rather, the RPI-27 would bind to the spike protein on the virus, thus preventing it from binding with a human cell.

About the author

Adele Peters is a staff writer at Fast Company who focuses on solutions to some of the world's largest problems, from climate change to homelessness. Previously, she worked with GOOD, BioLite, and the Sustainable Products and Solutions program at UC Berkeley, and contributed to the second edition of the bestselling book "Worldchanging: A User's Guide for the 21st Century."

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