Two new neolignans from Syringa velutina Kom.

Article abstract of DOI:10.3390/molecules14030953

Two new neolignans, (7S,8R)-guaiacylglycerol-8-O-4'-sinapyl ether 9'-O-β-D-glucopyranoside (1) and (7S,8R)-syringylglycerol-8-O-4'-sinapyl ether 9'-O-β-D-glucopyranoside (2) were isolated from the leaves of Syringa velutina Kom.. Their structures were est

Full text of DOI:10.3390/molecules14030953

Molecules 2009, 14, 953-958; doi:10.3390/molecules14030953
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molecules
ISSN 1420-3049
www.mdpi.com/journal/molecules
Communication
Two New Neolignans from Syringa velutina Kom.
1
,2,
2
2
3
2
1
Xue-Song Feng *, Yang Qu , Lei Xu , Da-Cheng Wang , Li-Jun Wu , Fan-Hao Meng and
1
Ya-Ru Liu
1
School of Pharmaceutical Sciences, China Medical University, Shenyang, Liaoning, 110001, P. R.
China; E-mails: fhmeng@cmu.edu.cn (F-H.H.), free1962514@yahoo.com.cn (Y-R.L.)
2
School of Traditional Chinese Medicines, Shenyang Pharmaceutical University, Shenyang,
Liaoning, 110016, P. R. China; E-mail: quyang_7@yahoo.com.cn (Y.Q.), abcgdef6001@163.com
(
L.X.), wulijun_111@hotmail.com (L-J.W.)
3
College of Animal Science and Veterinary Medicine, Jilin University, Changchun, Jilin, 130062, P.
R. China; E-mail: wdc9928@yahoo.com.cn (D-C.W.)
∗
Author to whom correspondence should be addressed; E-mail: xsfeng@mail.cmu.edu.cn; Tel.:
+86-13332495690.
Received: 8 January 2009; in revised form: 17 February 2009 / Accepted: 17 February 2009 /
Published: 27 February 2009
Abstract: Two new neolignans, (7S,8R)-guaiacylglycerol-8-O-4′-sinapyl ether 9′-O-β-D-
glucopyranoside (1) and (7S,8R)-syringylglycerol-8-O-4′-sinapyl ether 9′-O-β-D-gluco-
pyranoside (2) were isolated from the leaves of Syringa velutina Kom.. Their structures were
established by chemical properties and spectroscopic evidence.
Keywords: Syringa velutina Kom.; Neolignans.
Introduction
Syringa (S.) velutina Kom. has been widely cultivated in the northern parts of China and Korea. Its
leaves, flower buds, and bark have been used for many centuries in traditional Chinese medicine to
treat infectious fevers, counteract inflamations, dampness and acute icteric hepatitis [1]. A previous
phytochemical study on the genus Syringa led to the isolation of lignans, iridoid glucosides and so on
[
2]. For the purpose to finding more bioactive agents, a study on chemical constituents of S. velutina

Molecules 2009, 14
954
was carried out, and two new 8-O-4′ neolignans (compounds 1 and 2) along with four known lignans:
i.e. (+)-syringaresinol-di-O-β-D-glucopyranoside (3), (+)-medioresinol-di- O-β-D-glucopyranoside (4),
(
-)-olivil (5), (–)secoisrariciresinol-9- O-β-D-glucopyranoside (6) [2-4] were obtained. In this paper, the
isolation and structural elucidation of the two new compounds are reported.
Results and Discussion
Compound 1 was obtained as a white amorphous powder (MeOH) with a negative optical rotation
2
D
3
[
α] -9.1° (c=0.2, MeOH). The IR spectrum of 1 showed absorption bands at 3,321, 1,607, 1,500,
-
1
1
,064, and 1,021 cm , ascribable to hydroxyl, aromatic and ether functions. The positive- and
+
negative-ion HR-ESI-MS of 1 showed quasimolecular ion peaks at m/z 591.2062 [M+Na] and
-
5
67.2077 [M-H] , which revealed the molecular formula of 1 to be C27
H
36
O13. Acid hydrolysis of 1
with 1M HCl liberated D-glucose, which was identified by HPLC analysis using an optical rotation
1
detector [5]. The H-NMR spectrum of 1 showed signals assignable to one 1,2,4-trisubstituted
aromatic ring [δ 6.68 (1H, d, J = 8.1Hz), 6.71 (1H, dd, J = 8.1, 1.8 Hz), 6.90 (1H, d, J = 1.8 Hz)], one
1
,3,4,5-tetrasubstituted aromatic ring [δ 6.73 (2H, s)], which indicated a partial symmetric structure for
1
, one trans-double bond [δ 6.31 (1H, dt, J = 15.9, 5.4 Hz), 6.56 (1H, d, J = 15.9 Hz)], one anomeric
proton [δ 4.20 (1H, d, J = 7.8 Hz)], three methoxy groups [δ 3.72 (3H, s), 3.75 (6H, s)], along with
13
other alkyl groups signals. The C-NMR spectrum showed 27 carbon signals, including one 1,2,4-
trisubstituted aromatic ring [δ 133.5, 111.1, 147.2, 145.5, 114.9, 119.6], one 1,3,4,5-tetrasubstituted
aromatic ring [δ 132.1, 104.0, 153.0, 135.4, 153.0, 104.0], two olefinic carbons [δ 125.9, 131.5], one
glucose unit [δ 102.3, 73.7, 77.1, 70.3, 76.9, 61.3], three methyoxyl carbons [δ 55.7, 56.2, 56.2], and
four other alkyl carbon signals, the chemical shifts of which indicated the connection to an oxygen
atom. The direct correlations between the proton and carbon were assigned by its HSQC spectrum
(
Table 1). According to the spectral data above, the structure of 1 was supposed to contain one
guaiacylglycerol, one sinapyl alcohol [6] and one glucose moiety [7]. The glucose anomeric
configuration was assigned to be β based on the J-value of its anomeric proton. Furthermore, the
HMBC correlations between δ 4.11 (H-8) and δ 135.4 (C-4′), δ 4.20 (H-1″) and δ 68.8 (C-9′),
connected the partial structures above together. Irritating δ 4.77 (H-7), δ 4.11 (H-8) showed NOE
correlations in the difference Nuclear Overhauser Effect (dNOE) spectrum, which indicated that 1
possessed an erythro relative configuration. The relative structure was further confirmed by NOESY
correlations between H-8/H-2, 7, 6, and H-9(δ 4.40)/H-2, 6. Enzymatic hydrolysis of 1 with cellulase
gave the aglycone 1a. The erythro configuration was also confirmed by the J7, 8-value (3.8 Hz) of 1a
[
8]. The absolute structure of 1 was determined to be (7S, 8R) based on the negative cotton effects of 1
and 1a in its CD spectrum [8]. The results above identified the structure of 1 as (7S,8R)
guaiacylglycerol-8-O-4′-sinapyl ether 9′-O-β-D-glucopyranoside.

Molecules 2009, 14
Figure 1. Structures and key HMBC, NOESY correlations of compound 1, 2.
955
R
CH3
O
2'
7'
9'
5
HO
6
HO
3'
4'
9
O
4
1'
8
'
8
H C
7
3
6' HO
1
3
O
O
5'
2
O
H
H
OH
CH3 OH
OH
O
1"
1
2
R=H
R=OCH3
HMBC
NOESY
OH
1
3
1
Table 1. C-NMR (150 MHz), H-NMR (600 MHz) spectral data of compound 1, 2 and
HMBC correlations of 1 (in DMSO-d , δ ppm, J Hz).
6
1
2
position
HMBC
H→C)
δ
C
δ
H
δ
C
δ
H
(
1
2
3
4
5
6
7
8
133.5
111.1
147.2
145.5
114.9
119.6
72.2
132.6
6.90 (1H, d, J = 1.8 Hz)
C-1, 3, 4, 6, 7 104.4
6.60 (1H, s)
6.60 (1H, s)
147.6
134.4
6.68 (1H, d, J = 8.1 Hz)
6.71 (1H, dd, J =8.1, 1.8 Hz)
4.77 (1H, dd, J =4.8, 4.8 Hz)
4.11 (1H, m)
C-1, 3, 4, 6
147.6
C-1, 2, 4, 5, 7 104.4
C-1, 2, 6, 8, 9
C-4′
72.4
86.4
4.81 (1H, dd, J =4.8, 4.8 Hz)
4.15 (1H, m)
86.4
3
3
.39 (1H, m)
.69 (1H, m)
C-7, 8
3.40 (1H, m)
9
59.9
59.9
3.68 (1H, m)
1
′
132.1
104.0
153.0
135.4
131.5
125.9
132.0
103.9
152.8
135.5
131.4
125.8
2
3
′, 6′
′, 5′
6.73 (2H, s)
C-1′, 4′, 7′
6.75 (2H, s)
4
7
8
′
′
′
6.56 (1H, d, J = 15.9 Hz )
C-1′, 8′, 9′
C-1′, 7′, 9′
C-7′, 8′
6.57 (1H, d, J = 15.6 Hz )
6.34 (1H, dt, J = 15.6, 5.4 Hz )
4.19 (1H, dd, J = 14.4, 5.4 Hz)
4.41 (1H, dd, J = 14.4, 5.4 Hz)
6.31 (1H, dt, J = 15.9, 5.4 Hz )
4
4
.19 (1H, dd, J = 14.4, 5.4 Hz)
.40 (1H, dd, J = 14.4, 5.4 Hz)
8.08 (1H, s)
9
′
68.8
68.7
4
7
9
-OH
-OH
-OH
C-3, 4, 5
C-1, 7, 8
C-9
5.10 (1H, d, J = 4.8 Hz)
4.03 (1H, t, J = 6.0 Hz)
Glucose
1′′
2′′
3″
4′′
5′′
102.3
73.7
77.1
70.3
76.9
4.20 (1H, d, J = 7.8 Hz)
C-9′
102.2
73.6
77.0
70.2
76.9
4.21 (1H, d, J = 7.8 Hz)
3.05(1H,m)
2.99 (1H, td, J = 7.8, 4.8 Hz)
3.08 (1H, m)
3.09 (1H, m)
3.04 (1H, m)
3.07 (1H, m)
3.13 (1H, td, J = 9.0, 4.8 Hz)
3.14 (1H, m)
3
3
.43 (1H, m)
.67 (1H, m)
3.44 (1H, dd, J = 12.0, 6.0 Hz)
3.67 (1H, m)
6
′′
61.3
61.2

Molecules 2009, 14
956
Compound 2 was obtained as a white amorphous powder (MeOH) with a negative optical rotation
2
D
3
[
α] -9.4° (c=0.1, MeOH). The IR spectrum of 2 showed absorption bands at 3,308, 1,647, 1,541,
-
1
1
,489, 1,061, and 1,020 cm , ascribable to hydroxyl, aromatic and ether functions. The positive- and
+
negative-ion HRESI-MS of 2 showed quasimolecuar ion peaks at m/z 621.2161 [M+Na] and
-
5
97.2182 [M-H] , which revealed the molecular formula of 2 to be C H O . Acid hydrolysis of 2
2
8
38 14
with 1 M HCl liberated D-glucose, which was identified by HPLC analysis using an optical rotation
1
13
detector [5]. The H- and C-NMR spectral data of compound 2 were similar to those of 1. By
comparing the spectral data of 2 with those of 1, a syringylglycerol moiety [δ 132.0, 104.4, 147.6,
1
4
31.5, 147.6, 104.4] was observed instead of the guaiacylglycerol unit in 1. Irridiating δ 4.81 (H-7), δ
.15 (H-8) showed a NOE correlation in the dNOE spectrum, which indicated that 2 also possessed an
erythro relative configuration. Thus, the structure was identified as (7S,8R) syringylglycerol-
-O-4′-sinapyl ether 9′-O-β-D-glucopyranoside, which has the same stereostructure as 1 based on the
8
J-value of H-7 and negative Cotton effect in its CD spectrum .
Experimental
General
The following instruments were used to obtain physical data: specific rotations, Perkin-Elmer
241MC (l = 5 cm); UV spectra, Shimadzu UV-1700 spectrometer; IR spectra, Bruker IFS-55
spectrometer; high-resolution ESI-MS, LC-MSD-Trap-SL mass spectrometer; CD detector, JASCO
1
13
CD-2095-plus; H- and C-NMR spectra, Bruker AV-600 (600 MHz) spectrometer, with
tetramethylsilane as an internal standard; and HPLC instrument, Shimadzu LC-9A and SPD-M6A PAD
(
(
UV-VIS)detector; HPLC column, COSMOSIL 5C18-PAQ (250×4.6 mm i.d.) and YMC-PACK ODS-a
250×10 mm i.d.) columns were used for analytical and preparative purposes, respectively. The
following experimental conditions were used for chromatography: D101 macroporous resins (TianJin
Ou-Rui Bio-Tech Co. Ltd., Tianjin, P.R. China); ordinary-phase silica gel column chromatography,
Silica gel (200–300 mesh, Qingdao Haiyang Chemical, co. Ltd., Qingdao, P.R. China); TLC Silica gel
GF254 (normal phase, Qingdao Haiyang Chemical, Co. Ltd.); and detection was achieved by spraying
4 2 2 4
with 1 % Ce(SO ) -10 % aqueous H SO , followed by heating.
Plant material
The leaves of S. velutina Kom. were collected in Xinmin, Liaoning Province, China in May 2005
and identified by Prof. Qishi Sun (School of Traditional Chinese Medicine, Shenyang Pharmaceutical
University). A voucher specimen (No. 20050517) was deposited in the Herbarium of Section of
medicinal plants of Shenyang Pharmaceutical University.
Extraction and Isolation
The air-dried material (5 kg) was extracted with 70% ethanol (20 L) at room temperature for two
weeks. The extract was then filtered and concentrated under reduced pressure to afford a viscous mass

Molecules 2009, 14
957
(
1,560 g, 31.2 %), which was suspended in water and then subjected to D101 macroporous resin
chromatography [ethanol-water (0:100→30:70→50:50→70:30→100:0 v/v)]. Five fractions were
collected: the water soluble fraction (723 g, 14.5%), 30% ethanol-water soluble fraction (450 g, 9.0%),
50% ethanol-water soluble fraction (228 g, 4.6%), 70% ethanol-water soluble fraction (48 g, 1.0%)
and 100% ethanol soluble fraction (93 g, 1.9%). A part of the 30% ethanol-water soluble fraction (300
g) was subjected to column chromatography on silica gel (2000 g). The column was eluted with
CHCl -MeOH (100:0→50:1→30:1→10:1→0:100 v/v), and five fractions [Fr.1 (6 g), Fr.2 (44 g), Fr.3
3
(56 g), Fr. 4 (17 g), Fr. 5 (146 g)] were collected. Fraction 4 was further isolated by semi-prep. HPLC
(
MeOH:H O 40:60) to give 1 (14.1 mg, 0.0003 %) and 2 (10.1 mg, 0.0002%), respectively. The
2
compounds 1 and 2 were identified by [α] , NMR, MS, CD data
D
(
7S,8R)-Guaiacylglycerol-8-O-4′-sinapyl ether 9′-O-β-D-glucopyranoside (1). White amorphous
2
3
–1
powder (MeOH); [α] -9.1° (c=0.2, MeOH); CD (MeOH) Δε -9.4 (236); IR (KBr) νmax cm 3,321,
D
+
-
1
,607, 1,500, 1,064, 1,021; HRESI-MS m/z 591.2062 [M+Na] and 567.2077 [M-H] (calcd. for
1
3
1
C
27 36 35
H O13Na 591.2054 and C27H O13 567.2078); C- (150 MHz) and H-NMR (600 MHz) spectral
data see Table 1.
7S,8R)-Syringylglycerol-8-O-4′-sinapyl ether 9′-O-β-D-glucopyranoside (2). White amorphous
(
2
D
3
–1
powder (MeOH); [α] -9.4° (c=0.2, MeOH); CD (MeOH) Δε -9.8 (236); IR (KBr) νmax cm 3,308,
+
-
1
,647, 1,541, 1,489, 1,061, 1,020; HRESI-MS m/z 621.2161 [M+Na] and 597.2182 [M-H] (calcd. for
1
3
1
C
28 38 37
H O14Na 621.2159 and C28H O14 597.2183); C- (150 MHz), H-NMR (600 MHz) spectral data
see Table 1.
Acid hydrolysis of 1 and 2
Compound 1 (4 mg) and 2 (2 mg) were refluxed with 1M HCl in 75% EtOH (2 mL) for 7 hrs,
-
respectively. After cooling, the reaction mixture was neutralized with IRA-400 (OH form). Then, the
filtrate was extracted with EtOAc. The aqueous layer was subjected to HPLC analysis under the
following conditions: HPLC column, YMC-Pack NH
Co., Ltd, Japan); detection, optical rotation [Jasco OR-2090 Chiral Detector (Jasco Electric Co., Ltd.,
Japan)]; mobile phase, CH CN-H O (85:15, v/v); flow rate 1.0 mL/min; column temperature: room
temperature. Identification of D-glucose from 1 and 2 present in the aqueous layer was carried out by
comparison of its retention time and optical rotation with those of authentic sample. t : 11.4 min
positive optical rotation).
2
(NH12S05-2546WT), 250×4.6 mm i.d. (YMC
3
2
R
(
Enzymatic hydrolysis of 1
An aqueous solution (8.0 ml) containing 1 (7.0 mg) and cellulase (36 mg) was incubated at 40°C
for 4 d. The reaction mixture was extracted with EtOAc, and the EtOAc layer was evaporated under
reduced pressure. The residue was purified by silica gel column chromatography [CHCl
3 2
-MeOH-H O
3
0:3:1] to give (7S,8R) guaiacylglycerol-8-O-4′-sinapyl ether (1a, 2.5 mg). White amorphous powder
2
3
1
(
3
MeOH), [α]D +10.1° (c=0.1, MeOH). CD(MeOH) Δε -4.6 (236). H-NMR (CDCl , 600 MHz) δ:

Molecules 2009, 14
958
6
.98 (1H, d, J = 1.8 Hz, H-2), 6.88 (1H, d, J = 8.2 Hz, H-5), 6.76 (1H, dd, J = 8.2, 1.8 Hz), 4.98 (1H, d,
J = 3.8 Hz, H-7), 4.14 (1H, m, H-8), 3.52 (1H, dd, J = 12.1, 2.4 Hz, H-9 ), 3.93 (1H, m, H-9 ), 6.70
A
B
(
2H, s, H-2′, 6′), 6.58 (1H, d, J = 15.9 Hz, H-7′), 6.31 (1H, dt, J = 15.9, 5.5 Hz, H-8′), 4.38 (2H, d, J =
.5 Hz, H-9′).
5
Acknowledgments
This research was supported by National Key Project of Scientific and Technical Supporting
Programs funded by Ministry of Science & Technology of China (No. 2006BAD31B05)
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Sample Availability: Samples of compounds 1- 2 are available from the authors.
2009 by the authors; licensee Molecular Diversity Preservation International, Basel, Switzerland. This
©
article is an open-access article distributed under the terms and conditions of the Creative Commons
Attribution license (http://creativecommons.org/licenses/by/3.0/).