The residue was then
suspended in distilled water (500 mL) and partitioned
successively with CH2Cl2 (5 × 500 mL), EtOAc (5 × 500 mL),
and n-butanol (5 × 500 mL). The CH2Cl2 extract (4.1 g) then
was subjected to silica gel column (300 × 35 mm i.d.) eluted
with a gradient of petroleum ether-acetone (30:1 to 1:1, v/v) to
yield 12 fractions (D1-D12).