In a new study, researchers found in a test of antiviral effectiveness against COVID-19, an extract from edible seaweeds outperformed remdesivir, the current standard antiviral used to combat the disease.
In addition, heparin, a common blood thinner, and a heparin variant stripped of its anticoagulant properties, performed on par with remdesivir in inhibiting SARS-CoV-2 infection in mammalian cells.
The research was conducted by a team at Rensselear Polytechnic Institute.
The spike protein on the surface of SARS-CoV-2 latches onto the ACE-2 receptor, a molecule on the surface of human cells.
Once secured, the virus inserts its own genetic material into the cell, hijacking the cellular machinery to produce replica viruses.
But the virus could just as easily be persuaded to lock onto a decoy molecule that offers a similar fit. The neutralized virus would be trapped and eventually degrade naturally.
Previous research has shown this decoy technique works in trapping other viruses, including dengue, Zika, and influenza A.
In the study, the team tested antiviral activity in three variants of heparin (heparin, trisulfated heparin, and a non-anticoagulant low molecular weight heparin) and two fucoidans (RPI-27 and RPI-28) extracted from seaweed.
They performed a dose-response study known as an EC50 with each of the five compounds on mammalian cells.
They found RPI-27 yielded an EC50 value of approximately 83 nanomolar, while a similar previously published and independent in vitro test of remdesivir on the same mammalian cells yielded an EC50 of 770 nanomolar.
Heparin yielded an EC50 of 2.1 micromolar, or about one-third as active as remdesivir, and a non-anticoagulant analog of heparin yielded an EC50 of 5.0 micromolar, about one-fifth as active as remdesivir.
A separate test found no cellular toxicity in any of the compounds, even at the highest concentrations tested.
The team says the current thinking is that the COVID-19 infection starts in the nose, and either of these substances could be the basis for a nasal spray.
If doctors could simply treat the infection early, or even treat before people have the infection, they would have a way of blocking it before it enters the body.
They add that compounds from seaweed could serve as a basis for an oral delivery approach to address the potential gastrointestinal infection.
One author of the study is Jonathan Dordick, a professor of chemical and biological engineering at Rensselaer Polytechnic Institute.
The study is published in Cell Discovery.
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