Antiviral activity of the Echinacea purpurea extract Echinaforce® against the highly pathogenic avian influenza virus (H7N9)

The Echinacea purpurea extract Echinaforce^® has shown in recent years in vitro its strong inhibitory activity against respiratory viruses. The influenza A virus subtype H7N9 is a novel avian influenza virus first reported to have infected humans in 2013 in China. So far, 486 laboratory confirmed cases for this virus have been reported with 185 deaths [1]. These are the first experiments of a herbal extract to show antiviral activity against the H7N9 virus.

An ethanol extract (65% V/V) from fresh Echinacea purpurea roots (5%) and herba (95%) (Echinaforce^®), was tested on its ability to inhibit A/Anhui/1/2013 (H7N9) influenza virus via Focus Assay by using MDCK-II-cells. The test preparation was tested as a newly produced tincture, a concentrated spissum extract and an 8 year old tincture.

The newly produced tincture inhibited the viruses with an IC₅₀ of 7.01 µg/mL, the spissum extract with a IC₅₀ of 27.31 µg/mL, and the 8 year old tincture was still highly active with an IC₅₀ of 9.37 µg/mL.

The influenza A virus subtype H7N9 is a highly pathogenic virus for which no standard treatments are available either for treatment or for prevention. Here a standardized echinacea preparation showed good effects against the virus. As also an aged preparation showed similar results to a newly produced one, the antivirally active substances are obviously stable. Further research should elucidate the actives by analytically comparing these two preparations and also test their bioavailability.

References:

[1] WHO. Influenza at the human-animal interface. Summary and assessment as of 26 January 2015