Seaweeds have been widely studied for both their immune supporting properties and antiviral properties. In particular, studies have shown that fucoidan, a sulfated polysaccharide which exists in brown seaweeds, sea cucumbers and the egg sac of sea urchins, has potent immune system enhancement properties such as increased macrophage activity and the production of T-cells as well as potent antiviral activity including prevention of viral replication. A recent in vitro study by Kwon et al. published in the scientific journal Cell Discovery in July of 2020 studies the effects of heparin and fucoidans on the COVID-19 virus (SARS-CoV-2). The researchers in this study tested heparin, heparin sulfates and two types of fucoidan extracted from the brown seaweed and kelp Saccharina japonica: RPI-27 and RPI-28. All were found to have significant binding affinity to SARS-CoV-2, acting like a decoy and thus protecting the body’s own cells from binding to the virus. Of all the compounds tested, the fucoidan RPI-27 was the most effective, and RPI-28 was the second most effective. The researchers hypothesize that the superior ability of the fucoidans to bind to the virus are due to the shape of the molecule, which is highly branched. The heparin molecule is a straight chain. The effectiveness of RPI-27 in binding to the virus was “substantially” greater than the drug remdesivir, which is currently approved for emergency use in some countries for the treatment of severe COVID-19 infections. Fucoidan can be administered orally, through a nasal spray or inhaler whereas remesdivir has to be administered intravenously. Fucoidan showed no toxicity even at the highest concentrations that were tested, and previous studies have also reported no toxicity.

References

Kwon, P., Oh, H., Kwon, S-J., Jin, W., Zhang, F., Fraser, K., Hong, J., Linhardt, R., Dordick, J., July 2020. Sulfated polysaccharides effectively inhibit SARS-CoV-2 in vitro. Cell Discovery 6 (1). http://dx.doi.org/10.1038/s41421-020-00192-8