The residue fromthe above soluble free extraction was hydrolyzed
directly with 200 mL of 4 M NaOH solution at room temperature
for 1 h with shaking. The mixturewas adjusted to pH
2 with concentrated HCl and the bound phytochemicals was
extracted with ethylacetate. The eluate was evaporated under
vacuum at 45 C to dryness (Chu, Sun, Wu, & Liu, 2002).