OREANDA-NEWS. American biologists have found that rhamnan sulfate, a polysaccharide found in Monostroma nitidum algae used to wrap sushi, effectively suppresses the coronavirus. The authors hope that their discovery will lead to the creation of a plant-based antiviral drug. The results of the study are published in the journal Marine Drugs.

The SARS-CoV-2 coronavirus enters cells through the interaction of the RBD receptor-binding domain of its spike protein with the ACE2 receptor (angiotensin-converting enzyme 2) of the host cell. It is known that, in addition to ACE2, the RBD domain can bind to heparan sulfate and other polysaccharides located on the cell surface.

Researchers at the Rensselaer Polytechnic decided to test whether other polysaccharides, such as rhamnan sulfate, found in Monostroma seaweed, can block the coronavirus. This seaweed is grown in East Asia and South America for sushi wrappers. It was previously found that Monostroma nitidum polysaccharides effectively act as a prophylactic agent against Japanese encephalitis viral infection.

Using an anion exchange unit, the authors extracted rhamnan sulfate from the Monostroma nitidum powder and purified it. They then performed a detailed chemical analysis of the resulting substance using nuclear resonance magnetic spectroscopy.

The results showed that rhamnan sulfate effectively binds the SARS-CoV-2 spike protein, inhibits the ability of the coronavirus to attach and penetrate into cells, and inhibits the processes of transcription and translation. In experiments on cell cultures, he successfully neutralized a laboratory pseudovirus, including a variant with a set of mutations characteristic of the delta strain.

The authors believe that rhamnan sulfate, along with heparin and possibly other polysaccharides, could be a powerful tool against COVID-19.