Modified acid from lichen suppressed coronavirus activity
By obtaining a number of chemical modifications of usninic acid, a specific component of lichens, Russian scientists managed to significantly slow down the growth of three different strains of coronavirus.
In recent years, viruses, especially coronaviruses, have caused a lot of trouble. Many people have spent many months in self-isolation. At the same time, the pandemic has proved to be a powerful impetus for the development of virology and vaccine technology.
The active search for methods of treatment and prevention of coronavirus infections continues. For example, in a new study, Russian scientists examined the activity of derivatives of usninic acid. This substance is found in lichens - peculiar (including in terms of biochemistry) organisms formed by the symbiosis of fungus and algae. Usninic acid is among the special lichen substances that are synthesised only in lichens, and its name comes from the lichen genus Usnea sp.
The usninic acid molecule itself, or more specifically, (+)-usninic acid (the "+" sign indicates its optical activity and the right-hand direction of rotation of light passing through the solution), binds proteins on the surface of virions quite well. This inspired scientists to get a number of modified versions of this molecule and test how they would work on the coronavirus.
The chemical formula of the compound is quite complex: it includes cyclic structures, two of which combine six atoms, and one cycle consists of five. As is known, the structure of a chemical substance is inextricably linked to its chemical activity and biological properties. Therefore, by making structural changes in the molecule, scientists sought to change its effect on the virus and the process of infection of the cell.
The authors of the study turned the original molecule of usninic acid into 12 new substances. They differ in the structure of cycles and other individual parts of the molecule - the so-called substituents, or functional groups.
To learn the mechanism of action of modified usninovoy acid, the authors created so-called pseudovirus particles. They, like a real virus, carry on the surface of the spike proteins (S-proteins), necessary for binding to the host cell. It turned out that among the compounds obtained, five actually prevent pseudovirus particles from entering cells.
Usninic acid is found in a variety of lichens growing everywhere. This natural compound has a wide range of biological activity, and also acts as a convenient starting platform for the synthesis of new potential drugs. By means of small synthetic modifications of usninic acid, compounds with significant activity against three strains-variants of SARS-CoV-2 virus were obtained.