that was further separated by column chromatography
over silica gel (Merck Art 7734) and eluted with a gradient of hexane–
EtOAc (100% hexane, 90%, 80%, 70%, 60%, 50% and 40% hexane–EtOAc
each 5 L) to give seven fractions (A–G). Fraction A (2.5 g) was purified
by a Sephadex LH-20 column (150 g) with 80% CH2Cl2–MeOH (1.5 L)
to afford compound 3 (25.5 mg). Fraction B (1.5 g) was purified by