The air-dried and powdered leaves of M. alba (3 kg) were
extracted with methanol (5 L×3 times) at room temperature.
The combined extracts were concentrated to obtained crude
methanol residue (250 g)which was resuspended in water (2 L)
and successively partitioned in hexane (1 L×3 times) and ethyl
acetate (1 L×3 times). The organic layers were concentrated to
give 74 and 55 g of hexane and ethyl acetate residues,
respectively. A fractionation of the ethyl acetate extract on a
silica gel column eluted by a gradient of 0–100% methanol in
chloroformafforded eight fractions F1–F8. Fraction F6was passed
over a Sephadex LH20 column using chloroform–methanol 1:1 as
the mobile phase to give 1 (32.4 mg), 8 (3.6 mg), and 6
(70.0mg). Fraction F3 was chromatographed on a silica gel
column eluted by hexane–ethyl acetate (4:1 v/v) to afford 7
(6.2 mg), 5 (5.5 mg) and 9 (8.1 mg). Compounds 2 (3.0 mg), 3
(18.5mg), 4 (3.6 mg) and 10 (6.6 mg)were separated fromF4 by
using a reverse phase column eluted with methanol–water
(10:1 v/v). Compound 11 (11.0 mg) was purified from F7 on a
silica gel column using a mobile phase of hexane–ethyl acetate
(1:1 v/v).