Two new sesquiterpene glycosides from Pogostemon cablin

Article abstract of DOI:10.1080/10286020.2011.577424

Two new rearranged patchoulane sesquiterpene glycosides, 3α-hydroxypatchoulol 3-O-β-D-glucopyranoside (1) and 15-hydroxypatchoulol 15-O-β-D-glucopyranoside (2) together with rubusoside, a known diterpene glycoside, were isolated from the ethanol extract of the whole plant of Pogostemon cablin (Blanco) Benth. The structures of 1 and 2 were elucidated by spectroscopic analysis.

Full text of DOI:10.1080/10286020.2011.577424

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Two new sesquiterpene glycosides from
Pogostemon cablin
Wen-Bing Ding a b , Li-Dong Lin a , Mei-Fang Liu a & Xiao-Yi Wei a
a Key Laboratory of Plant Resources Conservation and Sustainable
Utilization , South China Botanical Garden, Chinese Academy of
Sciences , Guangzhou, 510650, China
b Graduate School of Chinese Academy of Sciences , Beijing,
100049, China
Published online: 22 Jun 2011.
To cite this article: Wen-Bing Ding , Li-Dong Lin , Mei-Fang Liu & Xiao-Yi Wei (2011) Two new
sesquiterpene glycosides from Pogostemon cablin , Journal of Asian Natural Products Research,
13:7, 599-603, DOI: 10.1080/10286020.2011.577424
To link to this article: http://dx.doi.org/10.1080/10286020.2011.577424
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Journal of Asian Natural Products Research
Vol. 13, No. 7, July 2011, 599–603
Two new sesquiterpene glycosides from Pogostemon cablin
Wen-Bing Dingab, Li-Dong Lina*, Mei-Fang Liua and Xiao-Yi Weia
aKey Laboratory of Plant Resources Conservation and Sustainable Utilization, South China
Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China; bGraduate School of
Chinese Academy of Sciences, Beijing 100049, China
(Received 18 January 2011; final version received 30 March 2011)
Two new rearranged patchoulane sesquiterpene glycosides, 3a-hydroxypatchoulol
3-O-b-D-glucopyranoside (1) and 15-hydroxypatchoulol 15-O-b-D-glucopyranoside
(2) together with rubusoside, a known diterpene glycoside, were isolated from the
ethanol extract of the whole plant of Pogostemon cablin (Blanco) Benth. The structures
of 1 and 2 were elucidated by spectroscopic analysis.
Keywords: Lamiaceae; Pogostemon cablin; sesquiterpene glycoside; 3a-hydroxy-
patchoulol 3-O-b-D-glucopyranoside; 15-hydroxypatchoulol 15-O-b-D-glucopyranoside
1. Introduction
were investigated, and two new rearranged
patchoulane sesquiterpene glycosides, tri-
vially named 3a-hydroxypatchoulol 3-O-
b-D-glucopyranoside (1) and 15-hydroxy-
patchoulol 15-O-b-D-glucopyranoside (2),
and the known diterpene glycoside rubuso-
side (3) [10] were isolated and character-
ized (Figure 1). Herein, we report the
isolation and structure elucidation of these
new compounds.
Pogostemon cablin (Blanco) Benth
(Lamiaceae), a bushy herb known as
patchouli, is native to tropical Asia and is
now cultivated in South China and other
tropical areas worldwide. It is used in
traditional Chinese medicine for the
treatment of upset stomach, vomiting and
diarrhea, headache, and fever [1]. Several
medicaments prepared from this plant
have been used in clinic in China [2].
Previous phytochemical studies have
focused on constituents in the essential
oil, which showed the presence of a
number of various sesquiterpenes. Patch-
oulol, a rearranged patchoulane sesquiter-
pene, was found to be the most abundant
constituent and to be the primary com-
ponent responsible for the typical patch-
ouli aroma [3–6]. Patchoulol was also
reported to possess antifungal [7,8] and
Ca2þ antagonist [9] activities. In continu-
ation of our phytochemical studies on the
medicinal plants growing in South China,
the hypophilic constituents of this herb
2. Results and discussion
Compound 1 was obtained as needle crystal
(methanol). The molecular formula was
determined as C21H36O7 from ESI-MS ions
at m/z 423 [M þ Na]þ, 399 [M 2 H]2, and
435 [M þ Cl]2 as well as the HR-ESI-MS
1
ion at m/z 423.2368 [M þ Na]þ. The H
and 13C NMR spectra (Table 1) showed the
presence of a b-D-glucopyranosyl moiety
[dH 5.01 (1H, d, J ¼ 7.8); dc 102.5, 75.2,
78.5, 71.9, 78.7, 63.0]. Acid hydrolysis of 1
with 1 mol/l HCl afforded b-D-glucose
20
(½aꢀD þ46.6, c ¼ 0.02, H2O) that was
*Corresponding author. Email: linld@scib.ac.cn
ISSN 1028-6020 print/ISSN 1477-2213 online
q 2011 Taylor & Francis
DOI: 10.1080/10286020.2011.577424
http://www.informaworld.com

600
W.-B. Ding et al.
12
13
11
HO
O
HO
1
10
3
5
7
H
OH
O
OH
O
H
O
HO
HO
15
OH
HO
HO
OH
2
1
Figure 1. Structures of 1 and 2.
identified by direct comparison with an
authentic sample. Besides, the 1H and 13
the 1H–1H COSY in combination with
HSQC showed connectivities from C-2 to
C-9 and of C-4 with C-15 as shown by bold
lines in Figure 2. In the HMBC spectrum
(Figure 2), long-range correlations were
observed from both H3-12 and H3-13 to
C-11, C-1, and 7, and from H3-14 to C-1,
C-5, C-9, and C-10, indicating that C-12
and C-13 were connected to both C-1 and
C
NMR spectra and DEPT experiment
indicated the presence of four methyl [dH
1.02, 1.14, 1.31 (each 3H, s), 1.21 (3H, d,
J ¼ 6.5 Hz)], four methylene, four meth-
ine, and three quaternary carbons, of which
a methine (dC 78.5) and a quaternary (dC
75.9) carbon were oxygenated. Analysis of
Table 1. 1H and 13C NMR spectroscopic data of compounds 1 and 2 (d in ppm).
1
2
Position
dC
dH
dC
dH
1
2
75.9
39.6
75.0
32.5
a-2.81 (dd, J ¼ 13.6, 6.0 Hz)
b-2.16 (m)
1.81 (m),
1.88 (m)
3
4
5
6
7
8
9
10
11
12
13
14
15
78.5
35.4
43.8
26.4
39.1
24.8
28.8
37.9
40.5
25.4
27.5
21.6
15.5
3.93 (td, J ¼ 10.7, 10.6, 6.0 Hz)
24.2
34.7
39.2
25.1
39.5
24.8
29.4
37.6
40.8
24.8
28.0
21.4
72.7
1.36 (m), 1.61 (m)
2.33 (m)
1.86 (m)
1.24 (m), 1.45 (m)
1.08 (m)
2.10 (m)
1.44 (m)
1.24 (m), 1.45 (m)
1.07 (m)
1.18 (m), 1.90 (m)
1.06 (m), 2.22 (m)
1.13 (m), 1.88 (m)
0.99 (m), 2.21 (m)
1.14 (s)
1.31 (s)
1.02 (s)
1.21 (d, J ¼ 6.5 Hz)
1.08 (s)
1.28 (s)
1.01 (s)
3.74 (dd, J ¼ 9.2, 6.4 Hz)
4.01 (m)
10
20
30
40
50
60
102.5
75.2
78.5
71.9
78.7
63.0
5.01 (d, J ¼ 7.8 Hz)
4.03 (t, J ¼ 7.8 Hz)
4.16 (m)
4.28 (m)
4.26 (m)
105.1
75.3
78.6
71.8
78.7
63.0
4.87 (d, J ¼ 7.8 Hz)
4.08 (dd, J ¼ 8.4, 7.8 Hz)
4.29 (dd, J ¼ 9.3, 8.4 Hz)
4.26 (dd, J ¼ 9.3, 8.4 Hz)
4.02 (m)
4.41(dd, J ¼ 11.5, 4.9 Hz)
4.43 (dd, J ¼ 11.6, 5.2 Hz)
4.55 (br dd, J ¼ 11.5, 1.8 Hz)
4.61 (dd, J ¼ 11.6, 2.0 Hz)
Note: 1H (400 MHz) and 13C (100 MHz) NMR in pyridine-d5.

Journal of Asian Natural Products Research
601
HO
HO
O
OH
O
OH
HO
HO
O
O
OH
2
1
HO
HO
OH
Figure 2. 1H–1H COSY (bold line) and main HMBC (arrow) correlations of 1 and 2.
C-7 via C-11, C-5 was connected with
C-10, and C-14 was bound to C-10. On the
basis of the above evidence, the aglycone of
1 was deduced to be a rearranged
patchoulane sesquiterpene [8,11] with a
basic structure closely similar to that of
patchoulol [11], except that C-3 was
oxygenated in 1. The glucose moiety was
attached to C-3 via a glycosidic linkage, as
deduced from the HMBC correlations of
H-10 with C-3 and H-3 with C-10. The
relative configuration of this compound
was determined by the NOESY experiment
and analysis of the proton coupling
constants. In the NOESY spectrum
(Figure 3), cross peaks were observed
betweenH-3/H3-13, H-3/H3-15, H-2a/H-4,
H3-14/H-2a, and H3-14/H-4. This in
combination with the axial–axial coupling
constants between H-3 and H-2
(J ¼ 6.0 Hz) and between H-3 and H-4
(J ¼ 10.6 Hz) showed a chair form (2C 5)
for the six-membered ring consisting of
C-1 , C-5 and C-10, with H-3 and 10-Me
in axial positions, whereas H-5, 4-Me, and
1-OH in equatorial positions. Therefore,
the structure of 1 was established as 3a-
hydroxypatchoulol 3-O-b-D-glucopyrano-
side (Figure 1).
Compound 2 was obtained as colorless
oil. It had the same molecular formula as
that of 1, as determined from the ESI-MS
and HR-ESI-MS data. The 1H and 13C
NMR spectra (Table 1) were closely similar
to those of 1 except for the absence of the
resonances for 4-Me and the oxymethine
C-3. Instead, the spectra indicated the
presence of an oxymethylene [dc 72.7, dH
3.74 (dd, J ¼ 9.2, 6.4) and 4.01]. On the
basis of the above evidence, the aglycone of
2 was determined as patchoulan-1, 15-diol
[12,13]. Acid hydrolysis of 2 afforded b-D-
glucose and patchoulan-1, 15-diol, which
were identified by comparison of 1H NMR
spectral data with those values in the
literature [12,13]. HMBC correlations
(Figure 2) were observed from H-15 to
C-10, and from H-10 to C-15, indicating the
attachment of b-glucopyranosyl moiety to
C-15. Therefore, the structure of compound
2 was determined as 15-hydroxypatchoulol
15-O-b-D-glucopyranoside (Figure 1).
As patchoulol and its derivatives were
reported to possess antifungal activity [6,7],
the antifungal properties of compounds 1
and 2 against Botrytis cinerea were tested,
and the result showed that both of them
were inactive at 100 ppm. At present,
patchouli plants are the only commercial
H
HO
H
H
RO
H
H
1
R = β-D-Glucose
Figure 3. Key NOESY correlations of 1.

602
W.-B. Ding et al.
source of patchoulol, and cost-effective
synthetic routes for enantiomeric pure
patchoulol have yet to be developed [4].
In our research, compounds 1 and 2 were
first obtained from the strong polarity part of
the patchouli plant extraction as the
precursors of the patchoulol, which cannot
be obtained by traditional steam distillation
[6]. These findings are valuable for making
the most use of the patchouli plants.
China Institute of Botany, Chinese Acad-
emy of Sciences, Guangzhou, China.
3.3 Extraction and isolation
The powdered air-dried whole plants of
P. cablin (19.5 kg) were extracted with
85% ethanol thrice, each for 48 h at room
temperature, and the extract was concen-
trated under reduced pressure to give
5000 ml of residue. The residue was
suspended in water and then sequentially
extracted with petroleum ether, EtOAc,
and n-BuOH. Then the n-BuOH layer was
evaporated under vacuum to yield a
BuOH-soluble fraction (480 g). The
n-BuOH-soluble fraction was subjected
to macroreticular absorbing resin D101
column and eluted with MeOH–H2O (0,
30%, 70%, 97%) to give four fractions
(fraction, weight (g): Fr. 1 . 100; Fr. 2,
78.4; Fr. 3, 33.3; Fr. 4, 21.7). Fraction 2
(78.4 g) was fractionated by silica gel CC
with chloroform–methanol (9:1–1:1) to
give eight fractions (fr.A–fr.H). Fraction
B (4.0 g) was further chromatographed on
an ODS column eluted with MeOH–H2O
mixtures of decreasing polarities (3:7 to
9:1) to obtain seven subfractions (B-1–B-
7). Subfraction B-3 (180 mg) was further
separated by HPLC using 50% MeOH to
afford 2 (29 mg). Fraction 3 (33.3 g) was
fractionated by silica gel CC with chloro-
form–methanol (9:1 to 6:4) and methanol
to obtain six fractions. Fr.3-3 (1.7 g) was
subjected to silica gel CC with petroleum
ether–acetone (4:6) to obtain four frac-
tions. The second fraction (78 mg) fol-
lowed by purification on a Sephadex LH-
20 column with MeOH as eluent was
separated by HPLC using 60% MeOH to
afford 1 (10 mg). Fr.3-4 (2.8 g) was
subjected to silica gel CC with petroleum
ether–acetone (2:8) to give four fractions.
The second fraction (800 mg) was sub-
jected to purification on a Sephadex LH-20
column with MeOH as eluent, then
separated by HPLC using 70% MeOH to
give compound 3 (5 mg).
3. Experimental
3.1 General experimental procedures
Melting points were determined on a
Yanagimoto Seisakusho MD-S2 micro-
melting point apparatusandare uncorrected.
Optical rotations were obtained on a
Perkin-Elmer 341 polarimeter with
MeOH as solvent. The IR spectra were
measured in KBr on a WQF-410 FT-IR
Spectrophotometer. The 1H (400 MHz),
13C (100 MHz), and 2D NMR spectra were
recorded on a Bruker DRX-400 instrument
using TMS as an internal standard. HR-
ESI-MS data were obtained on an API
QSTAR mass spectrometer in positive ion
mode. ESI-MS data were collected on
MDS XCIEX API 2000 LC/GC/MS
instrument in positive-ion mode. For
column chromatography (CC), silica gel
60 (100–200 mesh, Qingdao Marine
Chemical Ltd, Qingdao, China) and
Sephadex LH-20 (GE healthcare, Uppsala,
Sweden) were used. TLC was performed
on precoated plates (Kieselgel 60GF254,
Merck, Darmstdt, Germany).
3.2 Plant material
The whole plants of P. cablin were
purchased from Guangzhou Qingping Pro-
fessional Traditional Chinese Medicine
Market, Guangdong, China, in August
2007, and identified by Prof. Binhui Chen,
South China Botanical Garden, Chinese
Academy of Sciences, China. An authenti-
cated voucher specimen (no. 299295) has
been deposited at the herbarium of South

Journal of Asian Natural Products Research
603
3.3.1 3a-Hydroxypatchoulol 3-O-b-D-
glucopyranoside (1)
NMR d 75.9 (C-1), 65.3 (C-15), 40.1 (C-
11), 38.8 (C-7), 38.6 (C-5), 37.1 (C-10),
36.6 (C-4), 31.8 (C-2), 28.7 (C-9), 26.7 (C-
13), 24.7 (C-6), 24.2 (C-8), 24.1 (C-12),
23.3 (C-3), 20.5 (C-14). ESI-MS: m/z 237
[M 2 H]2, 273 [M þ Cl]2.
Colorless needle crystal; mp 188–1908C,
20
½aꢀD 2139.5 (c ¼ 1.0, MeOH). IR (KBr)
n
max 3388, 2933, 1635, 1463, 1382, 1307,
1234 cm21; 1H NMR (400 MHz, pyridine-
d5) and 13C NMR (100 MHz, pyridine-d5)
spectral data see Table 1; ESI-MS: m/z 423
[M þ Na]þ on positive mode, 399
[M 2 H]2 and 435 [M þ Cl]2 on negative
mode; HR-ESI-MS: m/z 423.2368
[M þ Na]þ (calcd for C21H36O7Na,
423.2353).
Acknowledgement
We thank Mr Ruiqiang Chen, Guangzhou
Institute of Chemistry, Chinese Academy of
Sciences, for 1D and 2D NMR spectroscopic
measurements.
3.3.2 15-Hydroxypatchoulol 15-O-b-D-
glucopyranoside (2)
20
References
[1] State Administration of Traditional Chi-
nese Medicine ‘Chinese Herbal Medi-
cine’, The Editorial Committee of
Codification Chinese Herbal Medicine
[M] (Shanghai Science and Technology
Publishing Press, Shanghai, 1999), Vol. 7,
p. 130.
Colorless oil; ½aꢀD 267.1 (c ¼ 1.0,
MeOH). IR (KBr) nmax 3394, 2935,
1
2362, 2134, 1650, 1436 cm21; H NMR
(400 MHz, pyridine-d5) and 13C NMR
(100 MHz, pyridine-d5) spectral data, see
Table 1; ESI-MS: m/z 423 [M þ Na]þ on
positive mode, 399 [M 2 H]2 and 435
[M þ Cl]2 on negative mode; HR-ESI-
MS: m/z 423.2329 [M þ Na]þ (calcd for
C21H36O7Na, 423.2353).
[2] Y.S. Chen, Canton J. Agr. Sci. 1, 109
(2007) (in Chinese)
[3] L.F. Hu, S.P. Li, H. Cao, J.J. Liu, J.L.
Gao, F.Q. Yang, and Y.T. Wang,
J. Pharm. Biomed. 42, 200 (2006).
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Clark, J. Chappell, and M. Schalk, Arch.
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[6] A. Doneliana, L.H.C. Carlsonb, T.J.
Lopesa, and R.A.F. Machado, J. Supercrit.
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[7] J. Wu, X. Lu, W. Tang, H.W. Kong, S.F.
Zhou, and G.W. Xu, J. Chromatogr. A.
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[8] J. Aleu, J.R. Hanson, R.H. Galan, and I.G.
Collado, J. Nat. Prod. 62, 437 (1999).
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[10] T. Tanaka, H. Kohda, O. Tanaka, F. Chen,
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[12] E. Trifilieff, Phytochemistry 19, 2467
(1980).
3.4 Acid hydrolysis of 1 and 2
Compound 1 (1.8 mg) in 1 mol/l HCl–
MeOH was heated at 808C for 8 h. After
cooling, the mixture was extracted with
CHCl3. The water layer was neutralized
with 8% NaOH and concentrated to afford
a pure sugar (0.24 mg). The sugar was
confirmed as D-glucose by comparing with
an authentic sample on TLC [silica-gel,
EtOAc–MeOH–H2O–AcOH (6.5:2.0:
1.5:1.5), Rf ¼ 0.40] and by measuring its
20
optical rotation (½aꢀD þ46.6, c ¼ 0.02,
H2O). Compound 2 was hydrolyzed to
give D-glucose (0.40 mg) and patchoulan-
1, 15-diol (0.28 mg) by the same method.
Patchoulan-1, 15-diol: white solid; mp
20
80–828C; ½aꢀD 238 (c ¼ 0.54, CHCl3);
1H NMR (600 MHz, CDCl3) d 0.87 (3H,
[13] B. Luu and O. Guy, Tetrahedron Lett. 26,
2211 (1975).
s), 1.08 (6H, s), 3.47 (2H, J ¼ 7.3 Hz); 13
C