Many factors such as solvent characteristics, ratio of solvent
and sample, extraction time and temperature, should be
taken into account when the extraction method is chosen (Huie,
2002; Kim and Verpoorte, 2010). Selection of a suitable solvent
is the most important step in optimizing the recovery of
desire components from a complex matrix. Thus, the preliminary
experiment using sonication, which is simple, rapid and has no limitation
regarding solvent type, was performed to determine the
suitable solvent. Using a single solvent, the recovery of didehydrostemofoline
was clearly increased with the increasing polarity
(acetone < acetonitrile < ethanol < methanol) (Fig. 2).