Could willow bark provides antiviral medicine?

Scientists in Finland have discovered that an extract of willow bark has broad-spectrum antiviral activity in cell sample experiments. The extract was effective against both enveloped coronaviruses, which cause colds and COVID-19, and non-enveloped enteroviruses, which cause infections such as flu and meningitis.

The extract was made by harvesting commercially grown willow branches, cutting the bark into pieces, freezing it, grinding it, and then extracting it using hot water. The scientists tested the extract against strains of Coxsackievirus A and B, as well as a seasonal coronavirus and COVID-19.

The extract was found to be effective in inhibiting viral activity and protecting cells from infection. It did not harm the cells themselves. A binding assay carried out on the COVID-19 samples showed that although the virus could enter cells even if treated with the extract, it could not reproduce once it was inside.

The scientists believe that the extract works by acting on the surface of the virus, rather than any given stage of its replication cycle. They also found that the extract was equally effective against enveloped and non-enveloped viruses.

The scientists also tested existing medical compounds derived from willow bark, as well as commercially prepared salixin extract and salixin powder. Of these, only the salixin extract showed antiviral activity, suggesting that the success of the scientists' willow bark extract could result from the interactions of different bioactive compounds.

Ref: Willow (Salix spp.) bark hot extracts inhibit both enveloped and nonenveloped viruses: study on its anti-coronavirus and anti-enterovirus activities, Frontiers in Microbiology

DOI: 10.3389/fmicb.2023.1249794