Sample Preparations for Analysis of Volatile Chemicals and
Antioxidant Assays. A plant sample (20 g) was placed in a 3 L
round-bottom flask with 1 L of deionized water. The solution was
steam-distilled at 55 °C for 4 h under reduced pressure (95 mmHg).
The distillate (900 mL) was extracted with 100 mL of dichloromethane
for 6 h using a liquid−liquid continuous extractor. After the
extract was dried over anhydrous sodium sulfate, the solvent was
evaporated using a rotary flash evaporator. The evaporation was
stopped when the volume was reduced to approximately 1 mL, and
then, the solvent was further removed under a purified nitrogen stream
until the volume was reduced to exactly 0.5 mL. This extract was used
for analysis and antioxidant activity assays (standard extract solution).
All extracts prepared were stored at 5 °C until use.