Inhibitory Activity of Honeysuckle Extracts against Influenza A Virus In Vitro and In Vivo

Area of Science:

• Phytochemistry
• Virology
• Pharmacology

Background:

• Honeysuckle has a long history of use in traditional Chinese medicine for influenza treatment.
• The specific active components and mechanisms of honeysuckle's antiviral action against influenza viruses require further elucidation.

Purpose of the Study:

• To identify the main active antiviral components in honeysuckle extracts against influenza viruses.
• To investigate the antiviral mechanisms of action, including neuraminidase inhibition.

Main Methods:

• Preparation and testing of four honeysuckle extracts (acids, flavonoids, total, and mixture).
• In vitro cytopathic effect reduction assays against H1N1, H3N2, and oseltamivir-resistant H1N1-H275Y.
• In vivo studies using mice infected with H1N1.
• Neuraminidase (NA) inhibition assays and time-of-drug addition experiments.

Main Results:

• All four honeysuckle extracts inhibited influenza virus replication in vitro.
• The acids-flavonoids mixture exhibited the strongest in vitro activity, with EC50 values comparable to oseltamivir and ribavirin.
• Honeysuckle acids extract demonstrated significant in vivo efficacy, alleviating pneumonia and improving survival rates in infected mice.
• Honeysuckle extracts showed broad-spectrum inhibition of influenza virus neuraminidase, with the flavonoid extract being most potent against H7N9 NA.

Conclusions:

• Honeysuckle acids and flavonoids are the primary active antiviral components.
• Honeysuckle extracts likely exert antiviral effects by inhibiting viral release through neuraminidase inhibition.
• The honeysuckle acids extract shows promise as a potential antiviral agent for influenza, including oseltamivir-resistant strains.