A hundred gram(100 g) ground sample was extracted with 500 ml
of petroleum ether (40–60 °C) in a soxhlet extractor for 12 h. The
air-dried, defatted sample was extracted with methanol (500 ml) for
12 h. The methanolic extract was partitioned with n-butanol and
water (1:1, v/v). After a thorough shaking, the mixture was allowed
to stand overnight and the n-butanol layer was separated in the
next day. The aqueous layer was washed five times with aliquots
of n-butanol until it became colorless. The pooled butanolic layer was
evaporated under reduce pressure to give a residue which was dissolved
in 100 mlmethanol and precipitated by adding a large amount of diethyl
ether to obtain a solid crystalline dark brown compound