Bioassay-guided fractionation of Eupatorium perfoliatum L. towards anti-influenza A-activity leads to dicaffeoyl quinic acids

Ethanolic extracts from Eupatorium perfoliatum L. (Asteraceae) are traditionally used for fever treatment. Furthermore reports on the use against viral-associated common colds are documented (Contramutan®). An ethanol-water extract (62%) from E. perfoliatum was found to be active in MTT and plaque reduction assay against influenza A virus (IAV) H1N1v 2009 with an IC50 of approx. 55 µg/ml due to an inhibition of viral entry. Bioassay-guided fractionation towards the active compounds led to the isolation of active fraction B (IC50 approx. 48 µg/ml). Further fractionation of B into EtOAc- and MeOH-soluble subfracti…