全 文 ：Received 6 Jan. 2004 Accepted 6 Aug. 2004
Supported by the 863 Hi-Tech Research and Development Program of China (2202AA2Z3222) and the Knowledge Innovation Program from
the Northwest Institute of Plateau Biology, The Chinese Academy of Sciences (CXLY-2002-7).
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Acta Botanica Sinica
植 物 学 报 2004, 46 (10): 1256-1260
A New Triterpenoid from Amoora dasyclada
WANG Huan1*, ZHANG Xiao-Feng1, YANG Shu-Min2, LUO Xiao-Dong2
(1. Northwest Institute of Plateau Biology, The Chinese Academy of Sciences, Xining 810001, China;
2. State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany,
The Chinese Academy of Sciences, Kunming 650204, China)
Abstract: Five compounds were isolated from the EtOH extraction of the stem of Amoora dasyclada
(How et T. Chen) C. Y. Wu (Meliaceae). On the basis of spectroscopic methods, their structures were
elucidated as 24, 25-epoxy-tirucall-7-ene-3, 23-dione (1), 24, 25, 26, 27-tetranortirucall-7-ene-3-oxo-23
(21)-lactone (2), taraxerone (3), taraxerol (4) and b-sitosterol (5). Among them, compound 1 was a new
triterpenoid, compounds 3-5 were firstly obtained from this plant; compound 2, an tetranortriterpenoid,
was firstly isolated from natural sources, and its NMR data were assigned for the first time. Moreover, the
D7-bond and the Me-14 in compound 2 were never changed, which has never been found in other
tetranortriterpenoids. And the biosynthetic pathway of tetranortriterpenoid was further discussed.
Key words: Amoora dasyclada ; Meliaceae; tetranortriterpenoid; 24, 25-epoxy-tirucall-7-ene-3, 23-dione;
24, 25, 26, 27-tetranortirucall-7-ene-3-oxo-23(21)-lactone
The genus Amoora, comprising about 25-30 species, is
mainly distributed in India and the Malay Peninsula. And
six species are found in Yunnan Province of China, one of
which is Amoora dasyclada (How et T. Chen) C. Y. Wu
(Yunnan Institute of Botany, 1977). Up to now, few studies
on its chemical constituents have been reported
(Daulatabad and Jamkhandi, 1997; Aboutabl, 2000; Luo et
al., 2000a; 2000b; 2001), and tetranortriterpenoids or
protolimonoids that were considered as chemotaxonomic
markers of the family Meliaceae have not been isolated
from this genus. However, a new protolimonoid (1) and a
tetranortriterpenoid (2), together with three known com-
pounds (3-5), were obtained from the stems of A.
dasyclada. In this paper, we describe the isolation and
structural elucidation of these compounds, and discuss
the biosynthetic pathway of tetranortriterpenoid.
1 Results and Discussion
The ethanolic extract of the stems from A. dasyclada
was partitioned between H2O and CHCl3, and the CHCl3-
soluble fraction was subjected to repeated silica gel CC to
yield five compounds: 24, 25-epoxy-tirucall-7-ene-3, 23-
dione (1), 24, 25, 26, 27-tetranortirucall-7-ene-3- oxo-23 (21)-
lactone (2), taraxerone (3), taraxerol (4) and b-sitosterol (5).
The known compounds 3 and 4 were identified by com-
parison of their spectroscopic data with those reported in
the literature (Sakurai et al., 1987), and compound 5 was
identified by co-TLC with an authentic sample. The struc-
tures of compounds 1 and 2 were established by using
spectroscopic method.
Compound 1 was assigned the molecular formula of
C30H46O3 by HREIMS. The 1H- and 13C-NMR spectra of
compound 1 showed signals for seven tertiary methyls,
eight methylenes, four methines (dC 52.6 (C-5), 48.7 (C-9),
53.2 (C-17), 32.9 (C-20)), four quaternary carbons (dC 48.1
(C-4), 35.3 (C-10), 43.9 (C-13), 51.6 (C-14)), a double bond
(dC 118.4 (C-7), 145.9 (C-8)), two ketonyl carbons (dC 217.1
(C-3), 207.2 (C-23)), and an epoxide group (dC 65.9 (C-24),
61.3 (C-25)). These data are similar to those of 24, 25-epoxy-
3b, 23-dihydroxy-7-tirucallene (6) (Luo et al., 2000a; 2000b),
which indicated compound 1 possessing a tirucallane or
euphane skeleton. Comparing the 1D-NMR data of com-
pound 1 with compound 6, compound 1 contained two
carbonyl groups instead of two hydroxyl groups. These
structural features were confirmed by HMQC and HMBC
(Fig.1). In the HMBC spectrum of compound 1, cross sig-
nals between C-3 with H-1, H-2, H-28, H-29, and C-23 with
H-20, H-22, H-24, H-26 were observed. It was presumed
that the C-20 configuration belongs to the tirucallane rather
than the euphane series, since tirucallane derivatives oc-
cur widely in the Meliaceae while euphanes are restricted
to Melia species (Purushothaman et al., 1985). And the
optical rotation of compound 1, [a]D22 –56.6° (c 0.52, CHCl3),
was similar to that of compound 6, [a]D22 – 47° (c 0.075,
WANG Huan et al.: A New Triterpenoid from Amoora dasyclada 1257
CHCl3) (Gray et al., 1988), which indicated it to be the
tirucallane rather than euphane series (Itoh et al., 1976;
Sherman et al., 1980). Thus, compound 1 was determined
to be 24, 25-epoxy-tirucall-7-ene-3, 23-dione.
Compound 2 possessed the molecular formula C26H38O3
as determined by EIMS and the 1D-NMR spectra. The 1H-
and 13C-NMR spectra of compound 2 were similar to those
of compound 1, except for the side chain. In the 1D-NMR
spectrum of compound 2, resonances for three methyls, an
epoxide group and a ketonyl carbon in the side chain were
disappeared. However, it showed signals for an ester group
(dC 176.9 (C-23), 72.3 (C-21)), a methylene (dC 34.7 (C-22))
and a methine (dC 39.0 (C-20)). These facts may be rightly
interpreted as that the side chain is cyclized with the loss of
four carbons to form a lactone. The above inference was
confirmed by the following HMBC correlations (Fig.1): H-
22 with C-17, C-20, C-21 and C-23; H-21with C-17, C-20, C-
22 and C-23; H-20 with C-17, C-21 and C-23; H-17 with C-12,
C-13, C-15, C-16, C-18, C-20 and C-21. Therefore, compound
2 was assigned as 24, 25, 26, 27-tetranortirucall-7-ene-3-
oxo-23 (21)-lactone. Although compound 2 had previously
been synthesized by oxidation in the process of ascertain-
ing several tirucallane derivatives’ structures (Breen et al.,
1966; Chan et al., 1970; Kumar et al., 1991), compound 2 is
not an artefact formed from compound 1 during isolation,
which was shown by the failure of synthesizing compound
2 by subjecting compound 1 to the isolation condition.
Tetranortriterpenoids were thought to arise from D7-
tirucallol or D7-euphol. According to Champagne et al.
(1992), in the biosynthetic pathway of tetranortriterpenoid,
the D7-bond is epoxidized to a 7-epoxide, which is then
opened inducing a Wagner-Meerwein shift of Me-14 to C-
8, formation of OH-7, subsequently the side chain is cy-
clized with the loss of four carbons. However, it is interest-
ing that the D7-bond and the Me-14 in compound 2 have
never been changed, which has never been found in
tetranortriterpenoids from natural sources previously. The
above inference indicated that the 7-epoxide and shift of
Me-14 to C-8 may not occur from a precursor to compound
2. And it was supported by the reactions in the references
(Breen et al., 1966; Chan et al., 1970; Kumar et al., 1991).
2 Experimental
2.1 General experimental procedures
All melting points were measured on an XRC-1
micromelting apparatus and uncorrected. Optical rotations
were measured with a Horbia SEAP-300 spectropolarimeter.
IR spectrum was obtained on a Bio-Rad FTS-135 infrared
spectrophotometer with KBr pellets. UV spectrum was taken
on a Shimadzu double-beam 210A spectrophotometer. MS
spectrum was obtained with a VG Auto Spec-3000
spectrometer, at 70 eV for EI. 1D- and 2D-NMR spectra
were recorded on a Bruker AM-400 and a DRX-500 MHz
spectrometer with TMS as internal standard. Silica gel (200-
300 mesh) for CC and GF254 for analytical TLC were from
the Qindao Marine Chemical Factory, China.
2.2 Plant materials
The stems of Amoora dasyclada (How et T. Chen) C. Y.
Wu were collected from Xishuangbanna, Yunnan Province,
China, in 2002, and identified by Prof. CUI Jing-Yun,
Xishuangbanna Botanical Garden, The Chinese Academy
of Sciences. A voucher specimen was deposited in the her-
barium of the Department of Taxonomy, Kunming Institute
of Botany, The Chinese Academy of Sciences, Kunming,
China.
2.3 Extraction and isolation
The air-dried stems (10 kg) of A. dasyclada were ex-
tracted with EtOH four times at room temperature, and the
solvent was evaporated in vacuo. The residue was sus-
pended in H2O and then extracted with CHCl3 three times.
The CHCl3 layer was concentrated in vacuo to give 258 g
of residue. Two hundred and ten grams of it was
chromatographed over silica gel. The column was eluted
with petroleum ether-EtOAc (from petroleum ether to pe-
troleum-EtOAc 1:1). According to differences in composi-
tion monitored by TLC (GF254), 14 fractions were obtained.
Crystal from fraction 2 (13.0 g) was washed intensively with
petrol-acetone (10:1) to afford compound 3 (620 mg). Crys-
tal from fraction 4 (5.0 g) was washed intensively with
Fig.1. The structures and key HMBC correlations of com-
pounds 1 and 2.
Acta Botanica Sinica 植物学报 Vol.46 No.10 20041258
acetone to afford compound 4 (360 mg). Fraction 6 (4.18 g)
was chromatographed on silica gel column eluted with
petrol-Me2CO (23:2) to give four subfractions (A-D). Crys-
tals from fraction B (910 mg) and C (927 mg) were washed
intensively with petrol-acetone (5:1) to afford compound 1
(44 mg) and 5 (300 mg), respectively. Ten grams of fraction
7 (27.2 g) was subjected to CC on silica gel with petrol-
EtOAc (24:4). Ten subfractions (E-N) were collected. Crys-
tals from fraction I (298 mg) and J (1.730 g) were washed
intensively with petrol-acetone (5:1) to afford compounds
1 (90 mg) and 5 (900 mg). Fraction M (2.2 g) was subjected
to CC on silica gel with petrol-EtOAc (9:1) to give three
subfractions (a-c). Fraction b (1.2 g) was chromatographed
over silica gel eluted with CHCl3 to get four subfractions
(Ⅰ-Ⅳ). Crystal from fraction Ⅰ(164 mg) was washed in-
tensively with petrol-acetone (5:1) to afford compound 2
(35 mg).
2.4 Identification
24, 25-Epoxy-tirucall-7-ene-3, 23-dione (1) C30H46O3,
colorless needles, mp 150-151 ℃, [a]D22.4 –56.62° (CHCl3, c
Table 1 1H-NMR (400 MHz) and 13C-NMR (100 MHz) data of compounds 1 and 2
H 1 2 C 1 2
1 1.95 (1H, m) 1.92 (1H, m) 1 38.8 t 38.3 t
1.44 (1H, m) 1.40 (1H, m)
2 2.72 (1H, td, 5.5, 14.5) 2.70 (1H, td, 5.5, 14.5) 2 35.2 t 34.4 t
2.19 (1H, m) 2.19 (1H, m)
3 217.1 s 216.5 s
4 48.1 s 47.7 s
5 1.68 (1H, m) 1.67 (1H, m) 5 52.6 d 52.2 d
6 2.05 (2H, m) 2.06 (2H, m) 6 24.6 t 24.2 t
7 5.27 (1H, d, 3.0) 5.28 (1H, dd, 3.2, 6.4) 7 118.4 d 118.5 d
8 145.9 s 144.6 s
9 2.25 (1H, m) 2.21 (1H, m) 9 48.7 d 48.0 d
10 35.3 s 34.9 s
11 1.53 (2H, m) 1.55 (2H, m) 11 18.5 t 17.5 t
12 1.75 (1H, m) 1.67 (1H, m) 12 33.8 t 31.6 t
1.61 (1H, m) 1.43 (1H, m)
13 43.9 s 43.6 s
14 51.6 s 50.5 s
15 1.47 (2H, m) 1.52 (2H, m) 15 34.2 t 34.0 t
16 1.91 (1H, m) 1.90 (1H, m) 16 28.6 t 27.2 t
1.30 (1H, m) 1.30 (1H, m)
17 1.48 (1H, m) 1.71 (1H, m) 17 53.2 d 50.8 d
18 0.82 (3H, s) 0.78 (3H, s) 18 22.3 q 22.5 q
19 0.97 (3H, s) 0.95 (3H, s) 19 13.1 q 12.6 q
20 2.01 (1H, m) 2.15 (1H, m) 20 32.9 d 39.0 d
21 0.87 (3H, d, 6.3) 4.33 (1H, t, 8.2) 21 19.8 q 72.3 t
3.87 (1H, t, 9.1)
22 2.51 (1H, dd, 2.5, 15.8) 2.50 (2H, m) 22 48.3 t 34.7 t
2.25 (1H, m)
23 207.2 s 176.9 s
24 3.31 (1H, s) - 24 65.9 d -
25 61.3 s -
26 1.39 (3H, s) - 26 25.1 q -
27 1.23 (3H, s) - 27 18.8 q -
28 1.01 (3H, s) 0.99 (3H, s) 28 24.8 q 24.4 q
29 1.08 (3H, s) 1.06 (3H, s) 29 21.9 q 21.4 q
30 0.98 (3H, s) 0.97 (3H, s) 30 27.7 q 27.1 q
WANG Huan et al.: A New Triterpenoid from Amoora dasyclada 1259
0.521). UV lMeOH nm (log e): 204 (3.62); IR n KBr cm-1: 2 963,
2 875, 1 707, 1 454, 1 386, 1 242, 1 158, 1 111, 1 062, 999, 968,
962, 836,765; 1H- and 13C-NMR spectral data see Table 1;
EIMS m/z (rel. int.): 454 [M]+ (94), 439 (92), 421 (10), 397 (6),
381 (58), 367 (69), 349 (17), 340 (68), 325 (100), 311 (17), 297
(17), 283 (11), 271 (32), 258 (5), 243 (23), 229 (10), 215 (9), 201
(13), 187 (17), 173 (14), 159 (13), 141 (15), 125 (21), 113 (42),
96 (16), 83 (22), 72 (10), 59 (6); HREIMS m/z [M]+ 454.345 8
(calcd. for C30H46O3, 454.344 7; error: -2.4×10-6).
24, 25, 26, 27-Tetranortirucall-7-ene-3-oxo-23(21)-lac-
tone (2) C26H38O3, colorless needles. Mp 189-190 ℃ (mp
194 ℃ (Breen et al., 1966); mp 188-189 ℃ (Chan et al.,
1970; Kumar et al., 1991)). [a]D17.7 –73.53° (CHCl3; c 0.102)
([a]D -73° (c 1.1) (Breen et al., 1966); [a]D -61.5° (c 0.4)
(Kumar et al., 1991)). UV lCHCl3 nm (log e): 239 (2.64); IR
n KBr cm-1: 2 952, 1 784, 1 708, 1 472, 1 457, 1 386, 1 368,
1 178, 1 037, 1 020, 993; 1H- and 13C-NMR spectral data see
Table 1; EIMS m/z (rel. int.): 398 [M]+ (28), 383 (100), 365 (7),
341 (2), 325 (1), 297 (3), 271 (2), 260 (5), 245 (7), 219 (4), 203
(3), 185 (5), 178 (5), 159 (7), 145 (8), 133 (12), 119 (14), 105
(14), 95 (13), 81 (12), 67 (4), 55 (8).
Acknowledgements: The authors are grateful to the
members of the analytical group in the Laboratory of
Phytochemistry, Kunming Institute of Botany, The Chi-
nese Academy of Sciences, for the spectral measurements.
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