Antiviral substances discovered within native plants in South Korea

Codonopsis lanceolata, more commonly referred to as "deodeok," is used as a medicinal herb in South Korea. It is cultivated in large quantities and has been an integral part of Korean cuisine across history. Aster koraiensis, or Korean starwort, is a common flower that resembles a daisy, which is only found in the Korean peninsula.

A team of researchers led by Director C. Justin LEE from the Life Science Institute (Center for Cognition and Sociality) within the Institute for Basic Science (IBS), South Korea, recently announced the discovery of new antiviral compounds derived from these two Korean native plants.

The researchers discovered that the saponins found within these plants were particularly effective at inhibiting SARS-CoV-2 infection by blocking membrane fusion, which allows the viruses to invade the host cells.

Coronaviruses are known to enter human cells via endosomes or fusion at the plasma membranes. In both of these two pathways, a process known as "membrane fusion" must occur between the coronavirus envelope and the cell membrane.

The research team revealed that two saponins (astersaponin I and lansemaside A) found within the two beforementioned plants are capable of blocking this fusion of the membrane between the coronavirus and human cells, thereby effectively blocking all the ways that the virus can infect its host.

SARS-CoV-2 variants such as omicron are more infectious than original one due to the mutations in the spike protein, which enhances their binding affinity with the ACE2 cell receptor. However, no matter how much the SARS-CoV-2 variants to increase its affinity, it will be unable to enter the cell if the whole membrane fusion process, which occurs after viral binding to the receptor, is blocked. That is, the membrane fusion inhibitor can effectively prevent the infection of SARS-CoV-2 variants regardless of the their affinity to human cell receptor.