S.-X. Qiu et al. / Phytochemistry 56 (2001) 775±780
779
connected to a MicroVax II computer (Digital) using
CuKa or MoKa radiations.
(3H, s, Me-19), 0.88 (3H, s, Me-29), 0.93 (3H, s, Me-30),
0.98 (3H, s, Me-18), 1.11 (3H, s, Me-17), 1.15 (3H, s,
Me-21), 1.19 (3H, s, Me-26), 2.09 (3H, s, Ac-Me), 3.65
(1H, dd, J=9.5, 5.7 Hz, H-24), 4.62 (1H, br.s, H-3b).
13C NMR (ppm from solvent CDCl3 signal at 77.0) ꢀ :
33.9 (t, C-1), 22.5 (t, C-2), 77.8 (d, C-3), 36.3 (s, C-4),
50.3 (d, C-5), 17.7 (t, C-6), 34.7 (t, C-7), 40.1 (s, C-8),
50.2 (d, C-9), 36.7 (s, C-10), 21.2 (t, C-11), 26.8 (t, C-12),
42.4 (d, C-13), 49.7 (s, C-14), 31.1 (t, C-15), 25.5 (t, C-
16), 49.4 (d, C-17), 15,1 (q, C-18), 15.6 (q, C-19), 86.0 (s,
C-20), 26.6 (q, C-21), 34.4 (t, C-22), 26.0 (t, C-23), 85.9
(d, C-24), 69.8 (s, C-25), 27.2 (q, C-26), 23.9 (q, C-27),
27.5 (q, C-28), 21.4 (q, C-29), 16.2 (q, C-30), 20.9 (q, Ac-
Me).
3.2. Plant material
Stem bark of A. lawii was collected in Cuc Phuong
National Park, Vietnam, and identi®ed by one of the
authors (DDS). Voucher specimens (No. MAF-1414B)
have been deposited in the Herbaria of the Cuc Phuong
National Park, Vietnam, and the Field Museum of
Natural History, Chicago, IL, USA.
3.3. Extraction and isolation
The milled, air-dried stem bark of A. lawii (4 kg) was
extracted with MeOH (9 1Â3) by maceration. The
resulting pooled extract was concentrated to dryness in
vacuo and defatted with n-hexane to aord a n-hexane-
soluble fraction (25 g). The defatted residue was then
suspended in H2O and partitioned with CHCl3 to give,
on drying under reduced pressure, 98 g of a CHCl3-
soluble fraction. This fraction demonstrated cytotoxic
activity against the LNCaP (hormone-dependent pros-
tate human cancer), KB (human oral epidermoid carci-
noma), and Col 2 (human colon cancer) cell lines with
ED50 values of 8.2, 11.9, and 9.0 mg/ml, respectively.
Fractionation of the CHCl3-soluble fraction was
initiated by column chromatography over silica gel (450
g) using a gradient mixture of petroleum and EtOAc (0±
100%) as eluent. Sixteen fractions were pooled on the
basis of their similar TLC patterns. Work-up of fraction
2 aorded compound b-amyrone (1.0 g) after recrys-
tallization from a mixture of petroleum ether and
CHCl3 (1:1). Work-up of fractions 4 and 5, followed by
recrystallization from CHCl3, resulted in the isolation of
b-amyrin (520 mg) and 2 (5.2 g). The epimeric mixture
of stigmasterol plus poriferasterol (400 mg) was isolated
from the work-up of fraction 6 and recrystallization from
CHCl3. Fraction 11 was further chromatographed on a
silica gel column (50 g) and eluted with a mixture of pet-
roleum/CHCl3/MeOH (20:20:1, v/v/v) followed by pre-
parative TLC (silica gel, solvent system: petroleum:
EtOAc=4:1) to aord compounds 1 (3.5 mg) and 3 (7
mg).
Crystal data for 2: C32H54O4, MW=502.75, monoclinic,
C2, a=30.2897(6) A, b=7.1071(2) A, c=13.8023(4) A,
ꢁ=90.0000 (2)ꢀ, ꢂ=95.3225(12)ꢀ, ꢃ=90.0000(10)ꢀ, V=
2958.44 (13) A, Z=4, crystal size: 0.5Â0.3Â0.23 mm,
R1=0.0507, WR2=0.1127. All unique diraction
maxima with 2ꢄ449ꢀ were collected using 2ꢄ:ꢄ scans
and graphite monochromated MoKa radiation. A total
of 7181 unique re¯ections were collected. The structure
was solved by direct methods (SIR92) re®ned by full-
matrix least-squares techniques.
Additional crystallographic details (atomic coordi-
nates and equivalent isotropic displacement coecients,
lists of structure factors, interatomic distances, angles,
anisotropic displacement coecients for non-hydrogen
atoms, hydrogen atom coordinates and their isotropic
displacement coecients) have been deposited at the
Cambridge Crystallographic Data Centre. The coordi-
nates can be obtained, upon request, from Dr. Olga
Kennord, University Chemical Laboratory, 12 Union
Road, Cambridge CB2 1EZ, UK.
Acknowledgements
This study was supported in part by grants (No. 94-
26147 and No. 96-44652) from the John D. and Catherine
T. MacArthur Foundation, Chicago, IL, USA.
References
(E)-Aglawone (1), white powder; mp 125±126ꢀC; [a]D
À0.1ꢀ (c, 0.2, MeOH); UV (MeOH) nm (log E) lmax
:
Betancor, C., Freirc, R., Hernandez, R., Suarez, E., Cortes, M.,
Pange, T., Parcard, C., 1983. Journal of the Chemical Society,
Perkin Trans. 1, 1119.
242 (3.82); IR (®lm) cmÀ1: 3350, 1718, 1640, 1065; H
and 13C NMR data are given in Table 1; Electrospray
MS/MS m/z: 317 [M+H]+, 281 [M+H-H2OÂ2]+;
HREIMS: 316.2410 for C21H32O2 (required 316.2402).
1
Hisham, A., Ajitha Bai, M.D., Fujimoto, Y., Hara, N., Shimada, H.,
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3.4. 20S, 24S-Epoxydammarane-25-ol-3ꢁ-yl acetate
(cabraleadiol monoacetate) (2)
Le, T. X., Le, M. H., Mai, V. T., 2000. Proceedings of the National
Seminar on Sustainable Development and Conservation of Biodi-
versity in Vietnam, 2±3 October 1998, Hanoi. Advances in Natural
Sciences 1: 63±72.
Colorless needle, mp 148±150ꢀC; 1H NMR (ppm from
solvent CDCl3 signal at 7.27) ꢀ: 0.84 (3H, s, Me-28), 0.87