Influenza A viruses can mutate rapidly, contributing to the development of resistance to existing antiviral medications.1 This ongoing challenge has encouraged researchers to explore natural products as potential sources of new antiviral compounds. Cat's claw, a tropical vine with a long history of traditional use, has recently drawn attention for its potential activity against influenza viruses.
The Study
Researchers investigated the anti-influenza activity of cat's claw extracts made from pulverized stem bark. The plant material was extracted using three different methods: 80% ethanol, hot water, and a 1% sodium bicarbonate solution.
The resulting extracts were tested in laboratory-grown cells to evaluate both cytotoxicity and antiviral activity against influenza A viruses. Oseltamivir, a commonly used antiviral medication, served as a positive control.
The Results
All three cat's claw bark extracts showed antiviral activity against influenza A. Researchers selected one extract for further testing because it showed strong antiviral activity while having relatively low toxicity to the cells.
This extract was active against several human influenza A strains, including a strain resistant to the antiviral drug oseltamivir. Additional experiments suggested that the extract acted directly on the virus itself. Viral replication was significantly reduced when influenza particles were exposed to the extract before infecting cells or when the virus and extract were added to cells at the same time.
Further testing supported these findings, showing that the extract could directly inactivate influenza virus particles. In comparison, oseltamivir acted at a later stage of viral replication.
What Does this Mean?
The findings suggest that cat's claw bark contains antiviral compounds capable of directly interfering with influenza A virus particles under laboratory conditions, including a strain resistant to antiviral medications. This distinct mechanism of action makes the results particularly interesting for future antiviral research.
However, this was an in vitro laboratory study, meaning the effects were observed in cells rather than in humans. Further research is needed to identify the specific bioactive compounds responsible for the observed activity and determine whether these findings could eventually translate into safe and effective applications in people.
Other plants studied for their potential antiviral properties include elderberry, echinacea, and licorice.
