Anti-Influenza Activity of Cetraria islandica Lichen Extracts in In Vitro Experiments

The toxicity and antiviral activity of extracts obtained by the methods of aqueous and ethanol extraction of bioactive substances from Cetraria islandica lichen as a raw material were studied. Aqueous and ethanol extracts of lichen were characterized by low toxicity with respect to the passaged MDCK cell culture and exhibited antiviral activity. The ethanol extract showed more potent in vitro antiviral activity against human A/H3N2 and avian A/H5N1 influenza viruses: in a concentration of 50 μg/ml, it suppressed replication of these viruses by 3.5 and 4 log 10 , respectively, while the aqueous extract inhibited replication of viruses by 2 and 6 log 10 , respectively, when taken in a concentration of 500 μg/ml that was 10-fold higher than the concentration of the ethanol extract.