The air-dried and pulverized leaves (1
kg) were extracted with MeOH for 48 h (2 × 500 mL) at room
temperature. The extracts were concentrated using a rotary evaporator
at 40 °C to give 113 g of crude extract. Vacuum liquid chromatography
(silica gel, 30−100% v/v EtOAc/petroleum ether gradient) of the leaf
extract (80 g) gave 10 fractions, ca. 250 mL each, which were
concentrated and analyzed by TLC using 4-anisaldehyde spray
reagent. The combined fractions 3−4, obtained by eluting with 50%