The fresh plants were kept in a refrigerator for no longer than three days prior to extraction. Cortex Magnoliae Officinalis was dried in a cool, dark room (room temperature 19°C, relative humidity 60%) and subsequently stored in a drum with silica gel desiccants until use. Before extraction, the plants were cut into 1 cm pieces with pruning scissors, except Rhizoma Imperatae and Cortex Magnoliae Officinalis which were milled into fine powder using a pulverizer mill (Christy & Norris, UK). Triplicate preparations of each sample were carried out.