A marine algae extract may help fight COVID-19, according to a test tube study published inPeerJ.

The marine algae known as ulva—or “sea lettuce”—is a dietary staple in places like Japan, New Zealand, and Hawaii, according to areport from Medscape. Now, the extract—known as ulvan—has been tested in a very preliminary study, wherein it has shown results.

The researchers exposed cells to SARS-COV-2 and then to two different crude ulvan extracts, one obtained through an HCl-based extraction process and one obtained through an ammonium oxalate (AOx)-based extraction process. The AOx-extracted ulvan had a higher average molecular weight, higher charge, and, importantly, 11.3-fold higher antiviral activity than the HCl-based extract.

The Medscape report, however, notes that because the extraction process had such a big impact on the antiviral properties of the ulvan, two questions arise: Is there an even better extraction process, that would further increase the antiviral impact? And: How sure can we be that the part of the extract with the antiviral impact is the ulvan, and not the chemicals used to extract it?

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There are many steps still to be taken—further test tube studies, and then animal studies, and then, if ulvan continues to show promise, human studies. However, the researchers are hopeful, concluding: “Our results strongly suggest that further bioassay-guided investigation into bioactivity of compounds found inUlvasp. ulvan extracts could lead to the discovery of novel anti-SARS-CoV-2 antivirals.”