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Enteroviruses also cause a vast number of diseases on a yearly basis, ranging from the mild, common cold to more severe infections like myocarditis and central nervous system infections. They are also associated with chronic infections such as type I diabetes. Currently, no antivirals have been clinically approved against enteroviruses and only one drug has been granted a conditional marketing authorization against coronaviruses by the European medicines agency (EMA).

There is a great need to find broadly acting, safe and sustainably produced antiviral agents that could complement the vaccines and drugs to fight viral infections. It has become important that one looks beyond the conventional routes and explore bioactive compounds from natural products to identify novel broad-spectrum antivirals. Nature is the biggest library of diverse and complex molecules that have not been explored to their full potential.

This study concentrates on the screening of different natural compounds for their antiviral potential against enteroviruses and coronaviruses and investigates their mechanism of action. Majority of the natural products were sourced from industrial side-streams and extraction of secondary metabolites was done in a sustainable manner, suggesting a possibility to contribute towards circular economy.

We found broad-spectrum antiviral activity of Salix bark extracts and specific Ganoderma sp. ferments against enveloped and non-enveloped viruses. These natural antivirals inhibited enteroviruses by stabilizing them and preventing their genome release. In contrast, the bark extract treatment led to disruption of coronaviruses. We also explored different purified polyphenolic compounds, that are typically found in these extracts. They exhibited potent antiviral efficacy against enteroviruses and their efficacy was improved by several folds when they were functionalized on the surface of nanoparticles. Polyphenols inhibited the infection by binding at multiple sites on the virus capsid, leading to clustering and stabilization of the virus. The bioactive potential of these compounds are likely to have value-added applications in the field of packaging, cosmetics, food, and medicines, as the chemical and pharmaceutical industries are always on the lookout for new materials of natural origin.

M.Sc. Dhanik Reshamwala defends his doctoral dissertation ”Broad-spectrum antivirals from nature: studies on efficacy and mechanisms” on 24 February 2023 at 12 noon. Opponent Professor Urs Greber (University of Zurich, Switzerland) and Custos Professor Varpu Marjomäki (Ģ��ֱ��). The doctoral dissertation is held in English.