INHIBITION OF INFLUENZA A VIRUS INFECTIVITY AND RNA-DEPENDENT RNA POLYMERASE ACTIVITY BY ANDROGRAPHIS PANICULATA ETHANOL EXTRACT

Hang Ding, Xiaokai Chen, Weilie Ma and Zhizhen Zhang

Abstract

Andrographis paniculata extracts exhibit many pharmacological properties, such as antibacterial, antioxidant, anti-inflammation, antipyretic and antiviral activities, the latter against Epstein-Barr virus, flavivirus, herpes simplex virus, and human immunodeficiency virus. Anti-influenza A virus (IAV) properties of A. paniculata ethanol extract (APE) were investigated in IAV-infected Madin-Darby canine kidney cells. APE at >0.5 mg/ml exhibited anti-IAV effect in a dose-dependent manner using CCK-8 and cytopathic assays. APE pre-treatment demonstrated better antiviral activity than post-treatment. APE in the same dose range significantly inhibited viral RNA-dependent RNA polymerase activity. In conclusion, ethanol extract of A. paniculata inhibited influenza A virus infectivity and replication in Madin-Darby canine kidney cells, the latter effect through, in part, inhibition of viral RNA-dependent RNA polymerase activity. The study demonstrates chemical constituents in APE could have potential for discovery and development of novel anti-influenza agents.