Evaluation of in vitro antiviral activity in methanol extracts against influenza virus type A from Korean medicinal plants

Methanol extracts from 101 Korean medicinal plants were tested for inhibitory activity against inuenza virus type A by means of a modied haemagglutination inhibition (HI) test. MM‐57, MM‐72, MM‐104 and MM‐110, four of 101 extracts tested exhibited strong anti‐inuenza virus type A activity at concentration ranges of 0.78–6.25 mg/mL, 0.78–3.13 mg/mL, 0.78–1.56 mg/mL and 0.0975–0.39 mg/mL, respectively. The extracts MM‐57, MM‐72 and MM‐110 showed very strong anti‐inuenza virus type A activity in the range 1.56–6.25 mg/mL, 1.56–3.13 mg/mL and 195–390 µg/mL, respectively. The four methanol extracts were weakly cytotoxic to red blood cells. These results demonstrated that four methanol extracts of Korean medicinal plants exhibit strong anti‐inuenza virus type A activity, and weak cytotoxic effects. They may inhibit attachment of the virus to the cell and may therefore be used for prophylaxis. Copyright © 2003 John Wiley & Sons, Ltd.