全 文 ：Received 28 Aug. 2003 Accepted 12 Oct. 2003
Supported by the National Natural Science Foundation of China (30171144).
* PhD of China Pharmaceutical University. Tel: +86 (0)25 85391244; E-mail: .
** Author for correspondence. Tel: +86 (0)25 85391246; Fax: +86 (0)25 85309639; E-mail: .
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Chemical Constituents of Dendrobium moniliforme
BI Zhi-Ming*, WANG Zheng-Tao**, XU Luo-Shan
(Department of Pharmacognosy, China Pharmaceutical University, Nanjing 210038, China)
Abstract: A new bibenzyl derivative, moniliformine, along with six known compounds, was isolated from
a orchid Dendrobium moniliforme (L.) Sw. The new compound was identified as 3,4-dihydroxy-5,4-dimethoxy
bibenzyl on the basis of 1D and 2D NMR experiments. The six known compounds were determined to be a-
dihydropicrotoxinin, n-triacontyl p-hydroxy-cis-cinnamate, n-octacostyl ferulate, b-sitosterol, daucosterol
and n-nonacosane, respectively. Among them, a-dihydropicrotoxinin was isolated for the first time from
the plant kingdom.
Key words: Dendrobium moniliforme; moniliformine; a-dihydropicrotoxinin
The traditional Chinese medicine “Shihu”, derived from
the dry or fresh stems of many plants of genus Dendrobium,
is usually used to clear heat and for the benefit of eyes. In
continuation of our investigation of genus Dendrobium
(Bi et al., 2001a; 2001b; 2003), a new phenolic compound
and six known compounds were obtained from
Dendrobium moniliforme (L.) Sw.
1 Results and Discussion
The ethanolic extract of the stems of D. moniliforme
was partitioned with petroleum ether and acetone,
successively. The acetone fraction was subjected to col-
umn chromatography to afford three compounds, viz.,
3,4-dihydroxy-5,4-dimethoxy bibenzyl (1) (Fig.1), a-
dihydropicrotoxinin (2) and daucosterol (3); the petroleum
ether fraction also afforded four compounds, viz., n-
triacontyl p-hydroxy-cis-cinnamate (4), n-octacostyl
ferulate (5), b-sitosterol (6) and n-nonacosane (7). Com-
pound 1 was a new compound, and named moniliformine.
Compound 2 occurred naturally for the first time.
Compound 1 was obtained as a viscous solid, UV lmax
(MeOH) at 203, 277 nm showed characteristic of a bibenzyl.
IR bands at 3 387 and 1 611, 1 512 cm-1 indicated hydroxyl
and aromatic groups. The HREIMS exhibited the molecu-
lar ion peak at m/z 274.120 7 corresponding to the molecu-
lar formula of C16H18O4 (calcd. 274.102 5). The 1H-NMR
spectrum of compound 1 exhibited a 4H signal at d 2.71 for
the characteristic bibenzylic protons (Juneja et al., 1985). Two
singlets at d 3.69 (3H, s) and 3.66 (3H, s) indicated two
aromatic methoxyl groups, and two singlets at d 6.66 and
6.33 (disappearing on deuterium exchange) revealed two
normal phenolic hydroxyls.
Its EIMS gave two intense peaks at m/z 153 (44) and 121
(base peak) arising from the cleavage of benzylic linkage.
The ion peak at m/z 153 required two hydroxyl and one
methoxyl groups at aromatic ring A, while the fragment ion
peak at m/z 121 required one methoxyl group at ring B.
In the 1H-NMR spectrum, the aromatic protons at d 7.01
(2H, d, J=8.2 Hz) and 6.78 (2H, d, J=8.2 Hz) due to a A2B2
system suggested the OCH3 at 4-position. The meta-
coupled signals at d 6.44 (1H, d, J=1.3 Hz) and 6.20 (1H, d,
J=1.3 Hz) indicated that the two hydroxyls and one methoxyl
were located at C-3, C-4 and C-5 in an asymmetric pattern.
In the COLOC spectrum, the signals at dH 2.71 (a, a-CH2)
correlated with the signals at dC 129.3 (C-2, 6), 108.7 (C-2) and
103.6 (C-6). The protons of the methoxy group (dH 3.66) and
H-6 (dH 6.20) exhibited correlations with C-5 (dC 146.9). All
the above data confirmed that the methoxyl group was lo-
cated at C-5 of ring A, and the two hydroxyl groups were at
C-3 and C-4, and another methoxyl group at C-4,
respectively. In conclusion, the structure of compound 1
was determined to be 3,4-dihydroxy-5,4-dimethoxy bibenzyl.
The assignment of the position was further confirmed by
the HMQC spectrum.
Compound 2 was obtained as a colorless crystal, with
mp 250-252 ℃ (dec.). The HREIMS exhibited the molecular
ion peak at m/z 294.113 4 corresponding to the molecular
formula of C15H18O6 (calcd. 294.110 3). The 1H- and 13C-
NMR data were similar to those of aducin (Gawell et al.,
1976), however, 1H-1H COSY spectrum of compound 2
showed that the hydroxyl group should be assigned at C-6
instead of C-4, and that the splitting of H-4 was due to
Acta Botanica Sinica
植 物 学 报 2004, 46 (1): 124-126
BI Zhi-Ming et al.: Chemical Constituents of Dendrobium moniliforme 125
coupling with H-3, 5, 12, indicating compound 2 to be a-
dihydropicrotoxinin (Fig.1), compound 2 has been synthe-
sized by Mercer and Robertson (1936).
2 Experimental
2.1 General experimental procedures
Melting points were determined using an Kofler micro-
melting point apparatus and uncorrected. UV spectra were
measured on a Shimadzu UV-2501 spectrometer. IR spectra
were obtained on KBr pellets using a Nicolet impact 410
spectrometer. The 1H- and 13C-NMR spectra were obtained
on Bruker ACF-300. 1H and 13C chemical shifts were refer-
enced to chloroform-d1 at dH 7.24 and dc 77.0 (using TMS as
internal standard), respectively. EIMS and HREIMS mea-
surements were carried out on a HP5989A spectrometer.
TLC and column chromatography were performed on plates
precoated with silica gel F254 and silica gel (200-300 mesh)
(Qingdao Marine Chemical Ltd., China), respectively. Sol-
vents were distilled prior to use.
2.2 Plant materials
The stems of Dendrobium moniliforme (L.) Sw. were
collected in Xishuangbanna, Yunnan Province of China in
July 2001. The plant was identified by Professor XU Luo-
Shan and the voucher specimen was deposited in Depart-
ment of Pharmacognosy, China Pharmaceutical University.
2.3 Extraction and isolation
The air-dried and roughly powdered aerial parts of D.
moniliforme (1 kg) were extracted four times with 95% etha-
nol under reflux. The extract was mixed with silica gel (100-
200 mesh), and extracted with petroleum ether and acetone,
successively. The acetone fraction (81.4 g) was separated
by CC (12 cm×120 cm) over silica gel (200-300 mesh, 1
kg) eluted with a petroleum ether-acetone gradient (9:1, 4 L;
8.5:1.5, 8 L; 8:2, 4 L; 1:1, 4 L). CC fractions (450 mL each)
were combined into 25 parts according to TLC monitoring.
Fraction 10 (1.2 g) was further separated by CC (3 cm×60
cm) over silica gel (200-300 mesh, 100 g) eluted with petro-
leum ether-acetone (9:1) to afford compound 1 (23 mg).
Fraction 15 (1.4 g) was isolated by CC to afford compound
2 (26 mg). Fraction 20 (1.8 g) was isolated by CC to afford
compound 3 (36 mg). The petroleum ether fraction (30.8 g)
was also separated by CC (10 cm×100 cm) over silica gel
(200-300 mesh, 700 g) eluted with a petroleum ether-ethyl
acetate gradient, yielding compound 4 (36 mg), 5 (17 mg), 6
(26 mg), 7 (49 mg), respectively.
2.4 Identification
Compound 1 C16H18O4, viscous solid, UV lmax (MeOH)
nm: 277, 203. IR nmax cm-1: 3 387 (OH), 2 935, 1 611, 1 512
(benzene ring), 1 464, 1 302, 1 242, 1 092, 827. HREIMS m/z:
274.120 7 (calcd. for C16H18O4 274.102 5). EI-MS m/z (%):
274 (M+, 40), 153 (44), 121 (100). 1H-NMR (300 MHz, CDCl3)
d: 7.01 (2H, d, J=8.2 Hz, H-2, 6), 6.78 (2H, d, J=8.2 Hz, H-3,
5), 6.44 (1H, d, J=1.3 Hz, H-2), 6.20 (1H, d, J=1.3 Hz, H-6),
2.71 (4H, m, a,a-CH2), 3.69 (3H, s, 4-OCH3), 3.66 (3H, s, 5-
OCH3). 13C-NMR (75 MHz, CDCl3) d: 157.3 (C-4), 146.9 (C-
5), 143.7 (C-3), 133.7 (C-1), 133.4 (C-1), 130.5 (C-4), 129.3 (C-
2, 6), 113.4 (C-3, 5), 108.7 (C-2), 103.6 (C-6), 55.7 (5-OCH3),
54.9 (4-OCH3), 37.6 (a-CH2), 36.7 (a-CH2).
Compound 2 C15H18O6, mp 250-252 ℃ (dec.). IR nmax
cm-1: 3 452 (OH), 2 970, 1 795, 1 771, 1 263, 1 125, 989, 732.
HREIMS m/z: 294.113 4 (calcd. for C15H18O6 294.110 3). EI-
MS m/z (%): 294 (M+, 9), 251 (13), 135 (43), 109 (100), 97
(42), 55 (48). 1H-NMR (300 MHz, CDCl3) d: 4.87 (1H, m,
J=3.2, 5.1 Hz, H-3), 4.47 (1H, d, J=3.4 Hz, H-2), 3.75 (1H, d,
J=3.5 Hz, H-8), 3.05 (1H, dd, J=3.2, 15.1 Hz, H-7b), 2.75 (1H,
d, J=4.6 Hz, H-5), 2.42 (1H, m, H-4), 1.95 (1H, d, J=15.0 Hz, H-
7a), 1.79 (1H, m, H-12), 1.35 (3H, s, 10-CH3), 1.06 (6H, dd, 13,
14-CH3). 13C-NMR (75 MHz, CDCl3) d: 174.8 (C-15), 168.8
(C-11), 86.2 (C-6), 80.1 (C-2), 78.1 (C-3), 72.5 (C-9), 61.3 (C-8),
50.8 (C-4), 50.2 (C-5), 47.1 (C-1), 45.5 (C-7), 25.5 (C-12), 22.0
(C-13), 20.9 (C-14), 16.6 (C-10), consistent with those of a-
dihydropicrotoxinin (Gawell and Leander, 1976).
Fig.1. Structures of compounds 1 and 2.
Acta Botanica Sinica 植物学报 Vol.46 No.1 2004126
Compound 3 C35H60O6, mp 287-289 ℃ (dec.). IR nmax
cm-1：3 426 (OH), 2 958, 1 463, 1 074, 1 022, consistent
with the standard substance of daucosterol.
Compound 4 C39H68O3, mp 73-74 ℃ (dec.). EI-MS
m/z (%): 584 (M+, 36), 556 (12), 418 (2), 164 (100). 1H-NMR
(300 MHz, CDCl3) d: 7.63 (2H, d, J=8.8 Hz, H-2, 6), 6.79 (2H,
d, J=8.8 Hz, H-3, 5), 6.84 (1H, d, J=12.8 Hz, H-1), 5.83 (1H, d,
J=12.8 Hz, H-2), 5.19 (1H, s, ArOH), 4.12 (2H, t, J=6.6 Hz, -O-
CH2-), 1.25 (br), 0.88 (3H, t, J=6.9 Hz, -CH3), consistent with
those of n-triacontyl p-hydroxy-cis-cinnamate (Li et al.,
1992).
Compound 5 C38H66O4, mp 70-72 ℃ (dec.). EI-MS
m/z (%): 586 (M+, 22), 530 (49), 502 (13), 194 (100), 177 (68),
137 (34), 69 (15), 57 (29). 1H-NMR (300 MHz, CDCl3) d: 7.61
(1H, d, J=15.9 Hz, H-1), 7.07 (1H, dd, J=1.8, 8.2 Hz, H-6), 7.03
(1H, d, J=1.8 Hz, H-2), 6.91 (1H, d, J=8.2 Hz, H-5), 6.26 (1H, d,
J=15.9 Hz, H-2), 5.90 (1H, s, ArOH), 4.19 (2H, t, J=6.6 Hz, -O-
CH2-), 3.92 (3H, s, -OCH3), 1.68 (2H, m, -OCH2CH2-), 1.25
(br), 0.88 (3H, t, J=6.4 Hz, -CH3), consistent with those of n-
octacostyl ferulate (Ma et al., 1998).
Compound 6 C29H50O, mp 137-139 ℃ (dec.). IR nmax
cm-1: 3 430 (OH), 2 960, 2 936, 2 890, 1 465, 1 382, 1 063, 1 054
(C-O), consistent with the standard substance of b-
sitosterol.
Compound 7 C29H60, mp 43-45 ℃ (dec.). 1H-NMR
(300 MHz, CDCl3) d: 1.23 (br), 0.95 (6H, t, 2×CH3), consis-
tent with the standard substance of n-nonacosane.
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(Managing editor: WANG Wei)