Fig. 1

Patchouli alcohol inhibited replication of IAV in vitro with low toxicity. a After 24 h exposure to Patchouli alcohol (100, 50, 25, 12.5, 6.25 μg/ml) in MDCK, A549 and 293FT cells, the cell viability of Vero cells was measured by MTT assay. Values are means ± S.D. (n = 3). b IAV (MOI = 1.0) infected MDCK cells were treated with PA at the indicated concentrations for 24 h, then the antiviral activity was determined by plaque assay. Values are means±S.D. (n = 3). c Infectious virus titers from single-cycle high-moi assays performed on MDCK cells infected with PR8, Vir09 and NWS and treated with the indicated concentrations of PA. Mean percentage infectious virus titers were calculated as a percentage of infectious virus titers from untreated cells for each drug treatment condition in an experiment. Values are means ± S.D. (n = 3). d Approximately 50–100 PFU/well of Vir09 virus was pre-incubated with different concentrations of PA for 60 min at 37 °C before infection. Then the virus-PA mixture was transferred to confluent cell monolayers in 6-well plates, incubated at 37 °C for 1 h and subjected to plaque assay. e Plaque number from plaque reduction assays performed on MDCK cells infected with Vir09 and treated with the indicated concentrations of PA. Values are means ± S.D. (n = 4). f Plaque number from plaque reduction assays performed on MDCK cells infected with PR8, Vir09 and NWS and treated with the indicated concentrations of PA. Mean percentage plaque numbers were calculated as a percentage of plaque numbers from untreated cells for each drug treatment condition in an experiment. Values are means ± S.D. (n = 3)