Silymarin efficacy against influenza A virus replication.

The anti-influenza A/PR/8/34 virus activity of silymarin was evaluated in MDCK cells and investigated the effect of silymarin on synthesis of viral mRNAs. Silymarin was investigated for its antiviral activity against influenza A/PR virus using a cytopathic effect (CPE) reduction method. Silymarin exhibited anti-influenza A/PR/8/34 virus activity of 98% with no cytotoxicity at the concentration of 100 μg/ml reducing the formation of a visible CPE. Oseltamivir also did show moderate antiviral activity of about 52% against influenza A/PR/8/34 virus at the concentration of 100 μg/ml. Furthermore, the mechanism of anti-influenza virus action in the inhibition of viral mRNA synthesis was analyzed by Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR), and the data indicated an inhibitory effect in late viral RNA synthesis compared with oseltamivir in the presence of 100 μg/ml of silymarin. Therefore, the potential of silymarin for use in treating influenza virus infection merits greater attention.