Inhibitory Activity of Extracts Isolated from Parmelia Lichen against Influenza A Virus (H1N1)

Aims: In the present study, we aim to investigate the antiviral effect against influenza A (H1N1) virus of extracts of Parmelia lichen using the MDCK cell line.

Methodology: Parmelia lichens species were collected and extracted using acetone and methanol solvents, then chemically analyzed by HPLC. The antioxidant of the lichen extracts was measured using the DPPH method, meanwhile, cytotoxicity and antiviral activity were tested using the CCK-8 method. The cytopathic effect and apoptosis of infected-cells were observed under microscopy and using Muse Annexin V and Dead Cell Kit stains in the Muse Cell Analyzer. Finally, to confirm the antiviral effects of lichen against influenza A virus, the relative expression level of viral mRNA PA-gene in MDCK cells was measured using the qRT-PCR method.

Results: Based on the in vitro assays, we found that methanolic extract of Parmelia lichen shows extremely high activity against IAV, which is a significantly higher cell viability (more than 40%); however, a relatively low apoptosis and cell death compared to positive IAV-infected cells. Furthermore, the methanolic lichen extracts showed a significant reduction (by 1.9 log-fold) of influenza A viral replication with concentration of 100 μg/mL.

Conclusion: Our results show that methanolic extracts of natural Parmelia lichen highly inhibited influenza A virus replication in vitro assays. This knowledge has, in turn, allowed the researchers to further explore the specific molecules from natural lichens for pharmaceutical biomaterials of a new anti-influenza therapy.