Osmunda regalis L.  hexahydrofarnesyl acetone ( = phytone) (11.8%), 2,4−di−t−butylphenol (6.8%), phytol (6.5%), hexadecene (4.1%), and octadecene (4.4%)  Plaque reduction assay, Coxsackie virus B4 type 2  2.24  [71]