Post on 10-Nov-2015
Chemical and Pharmaceutical Bulletin Advance Publication by J-STAGE DOI:10.1248/cpb.c15-00055
2015 The Pharmaceutical Society of Japan
Advance Publication
March 12, 2015
Chem. Pharm. Bull.
Note
Catunaroside I-L, Four New Triterpenoid Saponins from the Stem Bark of
Catunaregam Spinosa
Jun Li,b Xuan Huang,
a Xiao-Hong Jiang,
a Qi-Feng Zhu,
a Yun Yang,
a and
Guang-Chun Gao *
,a
a Key Laboratory of Natural Medicine and Health Food R & D Technology, College of
Medicine, Jiaxing University; NO.118, JiaHang Road, Jiaxing 314001, P. R. China: b Jiaxing
Academy of Agricultural Sciences;ShuangQiao Road, Jiaxing 314016, P. R. China.
* To whom correspondence should be addressed. E-mail: gaogcjx@163.com
Chemical and Pharmaceutical Bulletin Advance Publication
Abstracts: Four new triterpenoid saponins, Catunaroside I
[3-O--D-glucopyranosyl-(13)--D-glucopyranosyl-arjunic acid
28-O--D-glucopyranoside] (1), Catunaroside J
[3-O--D-glucopyranosyl-(12)-[-D-glucopyranosyl-(13)]--D -glucopyranosyl-arjunic
acid 28-O--D-glucopyranoside] (2), Catunaroside K
[3-O--D-glucopyranosyl-(12)-[-D-glucopyranosyl-(13)]--D-glucopyranosyl-tormenti
c acid] (3), and Catunaroside L
[3-O--D-glucopyranosyl-(12)-[-D-glucopyranosyl-(13)]--D-glucopyranosyl-pomolic
acid] (4), and two known triterpenoid saponin Arjunetoside (5) and RandiasaponinVII (6),
were isolated from the stem bark of Catunaregam spinosa. Their structures were elucidated
on the basis of their spectral data and chemical evidence.
Key words: Catunaroside I-L, triterpenoid saponin, Catunaregam spinosa, Rubiaceae.
Chemical and Pharmaceutical Bulletin Advance Publication
Catunaregam spinosa T. (Rubiaceae), distributed in tropical and semitropical areas, was
known as a folk medicine in India and Brazil for its antispasmodic, antidysenteric,
anti-inflammatory, immunomodulatory and antifertility properties.1-4)
Many phytochemical
research has been done on this plant, and coumarin glucosides,5)
iridoid glucosides, 1)
and
triterpenoid saponins4, 6, 7)
were found. Our previous investigations on this plant had led to the
isolation of iridioid,8)
norneolignans,9)
triterpenoid saponins.10, 11)
In continuation of our
studies on the plants, four new triterpenoid saponins, Catunaroside I-L, together with
Arjunetoside and RandiasaponinVII, were isolated from the n-BuOH extract of its stem bark
by preparative HPLC. The isolation and structure determination of those triterpenoid saponins
were elucidated in this paper.
Results and Discussion
Compound 1 was obtained as a colorless amorphous powder. The molecular formula
C48H78O20 was determined by a combination of NMR spectra and HR-ESI-MS which
exhibited a molecular ion peak at m/z: 997.4980 [M + Na] + (Calcd for C48H78O20Na:
977.4984). On acid hydrolysis, 1 afforded only glucose as sugar moiety that was identical to
an authentic sample by Silica gel TLC. The IR spectrum showed absorption bands at 3417
cm 1
(OH), 1726 cm 1
(C = O), 1643 cm 1
(C = C). The 13
C-NMR spectrum exhibited 48
signals, of which 30 were assigned to the aglycone moiety and 18 to the sugars. In the
1H-NMR spectrum, seven methyl protons ( 1.37, 1.05, 0.96, 1.14, 1.63, 1.14 and 0.98 ppm;
each 3H, s), one olefinic methine proton ( 5.49, br s), and three anomeric protons ( 4.91, d,
8.0 Hz; 5.29, d, 7.5Hz; 6.38, d, 8.0 Hz) were observed. The 13
C-NMR spectrum also showed
Chemical and Pharmaceutical Bulletin Advance Publication
seven methyl carbons at 28.4, 18.0, 16.6, 17.6, 24.9, 28.7 and 24.6 ppm, two olefinic
carbons at 122.9 and 144.3 ppm, three oxygenated methine carbons at 66.6, 95.7 and 81.0
ppm, and three anomeric carbons at 106.0, 105.9 and 95.9. Based on the above data, it was
deduced that 1 was an olean-12-ene type triterpenoid glycoside with three units of glucose.
The comparison of 1H- and
13C-NMR spectrum data of aglycone part of 1 with that of arjunic
acid 12)
indicated that compound 1 possessed a 2, 3, 19-trihydroxyolean-12-ene-28-oic
acidic aglycone. The chemical shifts of C-3 ( 95.7) and C-28 ( 177.2) 13) implied that 1 was
a 3, 28-bisdesmosidic glycoside. This hypothesis was also in agreement with the relatively
downfield shifts of anomeric protons ( 4.91, 6.38 ppm) and the corresponding upfield shifts
of anomeric carbons ( 106.0, 95.9 ppm). In the HMBC spectrum, significant correlations
between signals at 4.91(H-1) and 95.7 (C-3), 5.29 (H-1) and 88.9 (C-3), and 6.37
(H-1) and 177.2 (C-28) were observed. The -anomeric configurations of glucose units
were determined by the relatively large 3JH1, H2 coupling constants (7.5-8.0 Hz). Considering
above information compound 1 was elucidated as
3-O--D-glucopyranosyl-(13)--D-glucopyranosyl-arjunic acid
28-O--D-glucopyranoside.
Compound 2, a colorless amorphous powder, was analyzed to have the molecular formula
of C54H88O25 by its HR-ESI-MS spectrum (m/z: 1159.5563 [M + Na] +). Acid hydrolysis of 2
afforded glucose as the only sugar unit. The 13
C-NMR spectrum revealed 54 signals, of which
30 were assigned to the aglycone and 24 to the sugars. The 1H-NMR spectrum showed seven
methyl protons ( 1.28, 1.18, 0.92, 1.12, 1.60, 1.14, 0.97 ppm; each 3H, s), one olefinic
Chemical and Pharmaceutical Bulletin Advance Publication
methine proton ( 5.47, br s), and four sugar anomeric protons ( 4.82, d, J = 7.5 Hz; 5.38, d,
J = 7.5 Hz; 5.85, d, J = 7.5 Hz; 6.37, d, J = 8.0 Hz). The signals of seven methyl carbons at
28.2, 17.6, 16.7, 17.7, 24.9, 28.7 and 24.7 ppm, two olefinic methine carbons at 123.1 and
144.3 ppm, four sugar carbons at 104.5, 104.6, 103.6 and 95.9 ppm, and two carbons at
177.3 and 96.5 ppm linked to glycan part were also observed in the 13
C-NMR spectrum. The
above evidence revealed that 2 was a bisdesmosidic glycoside. And the aglycone part of this
compound was determined as 2, 3, 19-trihydroxyolean-12-ene-28-oic acid comparing the
1H and
13C NMR signals of 2 with those of 3-O--D-glucopyranosyl-2, 3,
19-trihydroxyolean-12-en-28-oic acid-28-O--D-glucopyranoside. 12) According to the 1H
and 13
C-NMR signals, the aglycone and sugar moieties of 2 were assigned based on the
2D-NMR spectra, and the exact glycosidic linkages were unambiguously confirmed by the
following HMBC correlations between H-1 ( 6.37) of a glucose and C-28 ( 177.3) of
aglycone part; H-1 ( 4.82) of the inner glucose and C-3 ( 96.5) of aglycone part; H-1 (
5.38) of the 3-O-glucose and C-3 ( 88.9) of inner glucose; H-1 ( 5.85) of the
2-O-glucose and C-2 ( 78.3) of inner glucose. The -anomeric configurations of the glucose
units were established by its 3JH1, H2 coupling constants (7.5-8.0 Hz). On the basis of above
results compound 2, named as Catunaroside J, was determined as
3-O--D-glucopyranosyl-(12)-[-D-glucopyranosyl-(13)]--D-glucopyranosyl-arjunic
acid 28-O--D-glucopyranoside.
Compound 3, also an amorphous powder, has the molecular formula of C48H78O20 as
indicated from its HR-ESI-MS (m/z 997.5001 [M + Na]+) spectrum. Acid hydrolysis implied
Chemical and Pharmaceutical Bulletin Advance Publication
that compound 3 only contained glucose by comparing Rf value with that of authentic sample.
The 13
C-NMR spectrum revealed 48 signals, of which 30 were assigned to the aglycone and
18 to the sugars. The 1H-NMR spectrum exhibited signals for seven methyl protons ( 1.28 s,
1.17 s, 0.88 s, 1.06 s, 1.70 s, 1.43 s and 1.12 d J= 6.5 Hz), one olefinic methine proton ( 5.56,
br s) and three sugar anomeric protons ( 4.82, d, J = 7.5 Hz; 5.38, d, J = 7.5 Hz; 5.85, d, J =
8.0 Hz). In the 13
C-NMR spectrum, the signals of seven methyl carbons at 28.2, 17.8, 16.6,
17.2, 24.7, 27.1 and 16.8 ppm, two olefinic methine carbons at 128.0 and 139.9 ppm, three
sugar carbons at 104.4, 104.7 and 103.6 ppm were observed. The above evidence suggested
that 3 may be an urs-12-ene type triterpenoid glycoside with three glucose residue. The NMR
characteristic carbon signals ( 66.6, 72.8 ppm) and proton signal ( 1.12 d J= 6.5 Hz)
suggested that the aglycone part was tormentic acid, then it was proved by comparing with
NMR data from reference.14)
The carbon signals in 13
C-NMR spectrum at 96.4 (C-3) and
180.6 (C-28) inferred compound 3 was a 3-O-monodesmosidic saponin. The -anomeric
configurations of the glucose units were established according to its 3JH1, H2 coupling
constants (7.5-8.0 Hz). The sequence of the glycan part connected to C-3 of the aglycone was
deduced from the following HMBC correlations: H-1 ( 4.82) of inner glucose with C-3 (
96.4) of aglycone part, H-1 ( 5.38) of 3-O-glucose with C-3 ( 88.9), and H-1 ( 5.85) of
2-O-glucose with C-2 ( 78.3). From the above evidence, compound 3 was identified as
3-O--D-glucopyranosyl-(12)-[-D-glucopyranosyl-(13)]--D-glucopyranosyl-tormentic
acid, named as Catunaroside K.
Chemical and Pharmaceutical Bulletin Advance Publication
Compound 4, obtained as an amorphous powder, was deduced to have the molecular
formula C48H78O19 as indicated from HR-ESI-MS (m/z: 981.5080 [M + Na]+) data. The IR
spectrum showed the presence of C=O group at 1741 cm-1
and a C=C group at 1659 cm-1
. The
1H-NMR spectrum revealed signals due to seven methyl protons ( 1.25 s, 1.20 s, 0.80 s, 1.02
s, 1.74 s, 1.45, s and 1.07 d, J = 7.0 Hz), an olefinic proton ( 5.59 br s) and three anomeric
protons ( 4.84, d, J = 7.6 Hz; 5.38, d, J = 7.6 Hz; 5.73, d, J = 7.6 Hz). The corresponding
signals at 28.0, 16.7, 15.5, 17.2, 24.7, 27.2 and 16.8 (seven methyl carbons) ppm, 128.0
and 140.0 (an olefinic carbons) ppm, and 105.1, 104.7 and 103.8 (three anomeric carbons)
ppm were also observed in 13
C-NMR spectrum. Based on above observations, the NMR
signals of 4 were in good agreement with those of sibiricasaponins B (pomolic acid
3-O-(3-O-sulfo)--L-arabinopyranoside) 15) except for the signals of 3-O-substituted sugar
moieties. Acid hydrolysis of 4 showed the only existence of glucose. The exact sugar
arrangement was determined to be
3-O--D-glucopyranosyl-(12)-[-D-glucopyranosyl-(13)]--D-glucose according to the
reported NMR data of aralia saponin V. 16)
The conclusion was then proved by the HMBC
correlations between signals at 4.84 (H-1) of inner glucose and 96.4 (C-3) of aglycone
part, 5.38 (H-1) of 3-O-glucose and 88.6 (C-3), and 5.73 (H-1) of 2-O-glucose and
79.3 (C-2). Thus compound 4 was elucidated as
3-O--D-glucopyranosyl-(12)-[-D-glucopyranosyl-(13)]--D-glucopyranosyl-pomolic
acid, named as Catunaroside L.
Chemical and Pharmaceutical Bulletin Advance Publication
Compound 5 and 6 were elucidated as Arjunetoside and RandiasaponinVII separately by
comparison of their spectrum data with data reported in the literatures (IR, MS, 1H and
13C-NMR).
12, 17)
Experimental
General
Silica gel (100-200 mesh and 200-300 mesh, Qingdao Haiyang Chemical Co., Ltd.),
Macroporous resin D101, Lichroprep RP-18 (Merck) and Sephadex LH-20 (Pharmacia) were
used for column chromatography. TLC was performed on precoated silica gel 60 F254 plates
(Qingdao Haiyang Chemical Co., Ltd.), and detection was achieved by 10% H2SO4-EtOH.
Semipreparative HPLC was carried out using an ODS column (YMC-Pack ODS-5-A, 250
10 mm i.d., 5m; YMC) on a Waters-600 HPLC system equipped with a Waters-996
photodiode array detector. IR spectra were measured with a Bruker EQUINOX55 infrared
spectrometer. 1
H and 13
C-NMR spectra were recorded on a Bruker DRX-500 spectrometer
(SiMe4 as internal standard). MS were obtained on MDS SCIEX API 2000 LC/MS/MS
instrument for ESI and Bruker BioTOF Q spectrometer for HR-ESI. GC analysis were done
on Agilent 1200 with HP-5 column (0.32 mm30 mm, 0.25 m) and 1200 FID detector.
Plant Material
The stem bark of C. spinosa, collected from Sanya, Hainan Province, P.R.China in
February 2006, was identified by professor Si Zhang (South China Sea Institute of
Oceanology, Chinese Academy of sciences). And a voucher specimen has been deposited in
Chemical and Pharmaceutical Bulletin Advance Publication
the South China Sea Institute of Oceanology, Chinese Academy of Sciences (accession
number: GKLMMM020).
Extraction and Isolation
The n-BuOH extract (170 g), obtained from air-dried and powered plant material using
method reported previously9)
, was passed through a macroporous resin (D101) column eluted
with H2O and EtOH-H2O (30:70, 60:40, 95:5) in turn. The EtOH-H2O (60:40) eluted portion
(35 g) from n-BuOH soluble fraction was subjected to silica gel CC eluted with
CHCl3-MeOH (90:10-50:50) to give fractions a-f. Fraction b was separated by Sephadex
LH-20 eluting with MeOH, then fractions 2-10 and 11-20 were purified by preparative HPLC
eluting with MeOH-H2O (45:55) and MeOH-H2O (50:50) to obtain compounds 1 (15 mg), 5
(12 mg) and 6 (12 mg) separately; Fraction f was rechromatographed to silica gel CC eluted
with CHCl3-MeOH-H2O (80:20:5), then fraction 12 was purified by preparative HPLC using
MeOH-H2O (48:52) to yield compound 2 (21 mg); The EtOH-H2O (95:5) eluted portion (10 g)
was subjected to silica gel CC eluted with CHCl3-MeOH (98:2-50:50) to give fractions A-G.
Fraction E was purified by sephadex LH-20 (MeOH), then separated by preparative HPLC to
obtain compound 3 (19 mg) using MeOH-H2O (65:35) and compound 4 (10 mg) using
MeOH-H2O (68:32).
Catunaroside I (1)
Colorless amorphous powder, []20D = + 12.7 (c = 0.5, MeOH). IR (KBr, cm1
) max: 3417,
1726, 1643. 1H-NMR (500 MHz, pyridine-d5) and
13C-NMR (125 MHz, pyridine-d5) data: see
Chemical and Pharmaceutical Bulletin Advance Publication
table 1 and table 2. ESIMS m/z: 997 [M + Na]+, 1013 [M + K]
+. HR-ESI-MS m/z: 997.4980
[M + Na]+ (Calcd for C48H78O20Na, 997.4984).
Catunaroside J (2)
Colorless amorphous powder, []20D = + 39.1 (c = 0.3, MeOH). IR (KBr, cm1
) max: 3420,
1735, 1640. 1H-NMR (500 MHz, pyridine-d5) and
13C-NMR (125 MHz, pyridine-d5) data: see
table 1 and table 2. ESI-MS m/z: 1159[M + Na]+. HR-ESI-MS m/z: 1159.5563 [M + Na]
+
(Calcd for C54H88O25Na, 1159.5512).
Catunaroside K (3)
Colorless amorphous powder, []20D = + 27.8 (c = 0.3, MeOH). IR (KBr, cm1
) max: 3419,
1730, 1643. 1H-NMR (500 MHz, pyridine-d5) and
13C-NMR (125 MHz, pyridine-d5) data: see
table 1 and table 2. ESI-MS m/z: 997 [M + Na]+, 1013 [M + K]
+. HR-ESI-MS m/z: 997.5001
[M + Na]+ (Calcd for C48H78O20Na, 997.4984).
Catunaroside L (4)
Colorless amorphous powder, []20D = + 40.3 (c = 0.5, MeOH). IR (KBr, cm1
) max: 3422,
1741, 1659. 1H-NMR (500 MHz, pyridine-d5) and
13C-NMR (125 MHz, pyridine-d5) data: see
table 1 and table 2. ESI-MS m/z: 981 [M + Na]+, 997 [M + K]
+. HR-ESI-MS m/z: 981.5080
[M + Na]+ (Calcd for C48H78O19Na, 981.5035).
Acid Hydrolysis of 1-6 and determination of the absolute configuration of glucoses.
Chemical and Pharmaceutical Bulletin Advance Publication
Acid hydrolysis of Compounds 1-6 was done using the method reported previously. 10)
The
sugars were identified by comparing of the Rf value with that of glucose on TLC plate eluted
with CHCl3-MeOH-H2O (8:7:1) solvent system, visualized with ethanol-10% H2SO4 spraying
and then heating. The sugar residue and the authentic samples of D-glucose and L-glucose
were dissolved in 0.2 ml anhydrous pyridine and L-cysteine methyl ester hydrochloride, then
warmed at 60oC for 1 h. The trimethylsilylation reagent trimethylsilylimidazole was added,
followed by warming at 60oC for 1 h. After drying the residue was partition between H2O and
cyclohexane. The cyclohexane layer was analyzed by GC using a HP-5 column. The
temperatures of the injector and detector were 270 and 280 oC, respectively. A temperature
gradient system used for the oven was started with 160 oC for 4 min and increased up to 240
oC at a rate of 6
oC/min. The retention time (24.15 min) of sugar residue were the same with
that of D-glucose.
Acknowledgments
This work was financially supported by the Grant of the 12th Five-year Plan for University
Key Academic Subject (Pharmacology), Zhejiang Province, CHINA, the Science and
Technology Program of Jiaxing (2013AY21047) and the 2011 Annual Jiaxing Key Science
and Technology Innovation Team.
Conflict of Interest
The authors declare no conflict of interest.
Chemical and Pharmaceutical Bulletin Advance Publication
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Chemical and Pharmaceutical Bulletin Advance Publication
Table 1. Selected 1H-NMR Spectroscopic Data of 1-4 in Pyridine-d5 (500, 125MHz )
Table 2. 13
C-NMR Spectroscopic Data of 1-4 in Pyridine-d5 (500, 125MHz )
Fig. 1. Structures of Compounds 1-6
Chemical and Pharmaceutical Bulletin Advance Publication
Table 1. Selected 1H-NMR Spectroscopic Data of 1-4 in Pyridine-d5 (500, 125MHz )
Position 1 2 3 4
2 4.00 3.94 3.93 2.04 m
3 3.24 (d, 9.5) 3.14 (d, 9.0) 3.16 (d, 9.0) 3.28 (dd, 4.4, 11.5)
12 5.49 (br s) 5.47 (br s) 5.54 (br s) 5.59 (br s)
18 3.53 (br s) 3.51 (br s) 3.03 (br s) 3.05 (br s)
19 3.57(br s) 3.55(br s)
23 1.37 (s) 1.28 (s) 1.28 (s) 1.25 (s)
24 1.05 (s) 1.18 (s) 1.17 (s) 1.20 (s)
25 0.96 (s) 0.92 (s) 0.88 (s) 0.80 (s)
26 1.14 (s) 1.12 (s) 1.06 (s) 1.02 (s)
27 1.63 (s) 1.60 (s) 1.70 (s) 1.74 (s)
29 1.14 (s) 1.14 (s) 1.43 (s) 1.45 (s)
30 0.98 (s) 0.97 (s) 1.12 (d, 6.5) 1.07 (d, 7.0)
3-O-
1 4.91 (d, 8.0) 4.82 (d, 7.5) 4.82 (d, 7.5) 4.84 (d, 7.6)
2 4.09 4.42 4.41 4.42
3 4.23 4.26 4.27 4.25
4 4.10 4.00 3.99 4.01
5 4.22 3.93 3.92 3.92
6 4.42, 4.53 4.31, 4.48 4.31, 4.49 4.30, 4.48
3-O-
1 5.29 (d, 7.5) 5.38 (d, 7.5) 5.38 (d, 7.5) 5.38 (d, 7.6)
2 4.12 4.21 4.32 4.28
3 4.30 4.22 4.23 4.25
4 4.19 4.16 4.16 4.17
5 4.25 4.28 4.31 4.30
6 4.42, 4.53 4.43, 4.53 4.47, 4.54 4.42, 4.55
2-O-
1 5.85 (d, 7.5) 5.85 (d, 8.0) 5.73 (d, 7.6)
2 4.06 4.06 4.04
3 4.15 4.16 4.15
4 3.93 3.92 3.98
5 3.92 3.91 3.90
6 4.18, 4.26 4.18, 4.26 4.17, 4.26
28-O-
1 6.38 (d, 8.0) 6.37 (d, 8.0)
2 4.23 4.22
3 4.04 4.05
4 4.38 4.36
5 4.37 4.30
6 4.25,4.32 4.43, 4.53
Overlapped proton signals are reported without designated multiplicity.
Chemical and Pharmaceutical Bulletin Advance Publication
Table 2. 13C-NMR Spectroscopic Data of 1-4 in Pyridine-d5 (500, 125MHz )
Position 1 2 3 4 Position 1 2 3 4
1 47.0 47.1 47.4 38.8 3-O-
2 66.6 66.6 66.6 26.4 1 106.0 104.5 104.4 105.1
3 95.7 96.5 96.4 89.5 2 75.5 78.3 78.3 79.3
4 40.7 41.0 40.3 39.6 3 88.8 88.9 88.9 88.6
5 55.7 55.8 55.7 55.9 4 69.7 69.9 69.9 70.1
6 18.7 18.8 18.7 18.6 5 78.1 78.0 78.0 77.7
7 33.0 33.1 33.4 33.5 6 62.2 63.5 63.5 63.4
8 40.2 40.2 40.9 40.3 3-O-
9 48.2 48.3 47.7 47.7 1 105.9 104.6 104.7 104.7
10 38.0 38.0 37.8 36.9 2 74.3 74.2 76.2 76.4
11 24.2 24.2 24.0 24.0 3 78.7 78.7 78.7 78.6
12 122.9 123.1 128.0 128.0 4 71.6 71.6 71.6 71.6
13 144.3 144.3 139.9 140.0 5 78.3 78.8 78.8 78.6
14 42.2 42.2 42.4 42.4 6 62.2 62.2 62.2 62.6
15 29.0 29.0 29.3 29.3 2-O-
16 28.0 28.0 26.4 26.4 1 103.6 103.6 103.8
17 46.5 46.5 48.3 48.3 2 75.5 75.5 75.4
18 44.6 44.6 54.6 54.6 3 78.6 78.6 78.6
19 81.0 81.1 72.8 72.7 4 72.8 72.7 72.7
20 35.5 35.6 42.1 42.1 5 77.9 77.9 77.8
21 28.9 29.0 26.9 27.0 6 62.4 62.3 62.4
22 33.1 33.2 38.5 38.5 28-O-
23 28.4 28.2 28.2 28.0 1 95.9 95.9
24 18.0 17.6 17.8 16.7 2 74.1 74.2
25 16.6 16.7 16.6 15.5 3 78.9 79.0
26 17.6 17.7 17.2 17.2 4 71.1 71.1
27 24.9 24.9 24.7 24.7 5 79.3 79.3
28 177.2 177.3 180.6 180.7 6 62.5 62.2
29 28.7 28.7 27.1 27.2
30 24.6 24.7 16.8 16.8
Chemical and Pharmaceutical Bulletin Advance Publication
Fig. 1. Structures of Compounds 1-6