New triterpenoid saponins from the roots of Platycodon grandiflorum

Article abstract of DOI:10.1016/j.tet.2004.12.032

Bioassay-directed fractionation of the antiviral active fraction of the roots of Platycodon grandiflorum leads to the isolation of three new triterpenoid saponins, platycosides G1-G3 (1-3), as well as two known saponins, platycodin D3 (4), and platycoside E (5). The structures of the new compounds were elucidated on the basis of their spectral data and chemical evidences. The isolated saponins were tested for their antiviral activities against respiratory syncytial virus (RSV), herpes simplex type 1 virus (HSV-1) and influenza type A virus (Flu A). Compound 4 showed weak anti-RSV activity.

Full text of DOI:10.1016/j.tet.2004.12.032

Tetrahedron 61 (2005) 2211–2215
New triterpenoid saponins from the roots
of Platycodon grandiflorum
Zhendan He,a Chunfeng Qiao,a Quanbin Han,a Ying Wang,b Wencai Yeb and Hongxi Xua,
*
aChinese Medicine Laboratory, Hong Kong Jockey Club Institute of Chinese Medicine, Shatin, Hong Kong, People’s Republic of China
bDepartment of Phytochemistry, China Pharmaceutical University, Nanjing 210009, People’s Republic of China
Received 4 November 2004; revised 30 November 2004; accepted 1 December 2004
Available online 20 January 2005
Abstract—Bioassay-directed fractionation of the antiviral active fraction of the roots of Platycodon grandiflorum leads to the isolation of
three new triterpenoid saponins, platycosides G1–G3 (1–3), as well as two known saponins, platycodin D3 (4), and platycoside E (5). The
structures of the new compounds were elucidated on the basis of their spectral data and chemical evidences. The isolated saponins were tested
for their antiviral activities against respiratory syncytial virus (RSV), herpes simplex type 1 virus (HSV-1) and influenza type A virus (Flu A).
Compound 4 showed weak anti-RSV activity.
q 2004 Elsevier Ltd. All rights reserved.
1. Introduction
sorted by DEPT experiments into six methyl, 15 methene,
35 methine, and eight quaternary carbons. Its molecular
formula of C64H104O34 was determined by HRFABMS. The
spectral features and physicochemical properties revealed 1
to be a triterpenoid saponin. The IR spectrum exhibited
absorptions at 3400 cmK1 (OH), 1742 cmK1 (ester
carbonyl), and 1644 cmK1 (double bond). The five tertiary
methyl groups (d 1.01, 1.08, 1.12, 1.38, and 1.68) and one
olefinic proton (d 5.63, br s) were observed in the 1H NMR
spectrum. The 13C NMR spectrum showed five sp3 carbons
at d 17.4, 18.8, 24.4, 26.7, and 33.0, and two sp2 olefinic
carbons at d 122.8 and 144.0, and five oxygenated methene
and methine carbons at d 68.6, 88.5, 73.7, 63.1 and 67.1 (see
The roots of Platycodon grandiflorum (Jacq.) A. DC.
(Campanulaceae) have been used in antiphlogistic, anti-
tussive and expectorant as a traditional Chinese medicine,1
and it contains the abundance of saponins. Since Oshika first
studied its saponin in 1918,2 over 20 triterpenoid saponins
have been reported.3–10 Some of them showed anti-
inflammatory, antitumor and immunomodulatory
activities.11–13 During our investigation of antiviral con-
stituents from the traditional Chinese medicine,14,15 the
MeOH extract of the roots of P. grandiflorum exhibited the
inhibitory effect against respiratory syncytial virus (RSV)
(IC50 44.1 mg/ml). The constituents of active MeOH extract
were isolated by the bioassay-directed fractionation, and
purified to yield three new trace triterpenoid saponins,
platycosides G1–G3 (1–3), with two known platycodin D3
(4) and platycoside E (5) by preparative HPLC. In this
paper, we report their structural determination and antiviral
activities against HSV-1, RSV and Flu A.
1
Table 2). The information of H NMR spectrum coupled
with 13C NMR spectrum indicated that 1 possessed a
2b,3b,16a,23,24-pentahydroxyolean-12-ene-28-oic acidic
aglycon.9 The chemical shifts of C-3 (d 88.5) and C-28 (d
175.7) revealed that 1 was a bisdesmosidic glycoside.
Thirty-four of 64 carbons were assigned to the oligo-
1
saccharide moieties. The H and 13C NMR spectra of 1
exhibited six sugar anomeric protons at d 4.83 (d, JZ
7.3 Hz), 4.74 (d, JZ8.2 Hz), 5.03 (d, JZ7.7 Hz), 6.43 (br
s), 5.76 (br s), and 5.15 (d, JZ7.5 Hz) and carbons at d
105.8, 104.7, 105.4, 93.3, 100.8, and 106.5 (see Tables 1 and
3). The monosaccharides were identified as arabinose,
rhamnose, xylose, and glucose by TLC and a combination
of DEPT, TOCSY, HMQC, and HMBC experiments,
respectively. Comparing with NMR spectrum of platycoside
E (5), the absence of apiose in 1 was also disclosed.
Saponins 1 and 5 were further completely acid hydrolyzed
in the parallel condition. The results exhibited that the
2. Results and discussion
Platycoside G1 (1) was obtained as an amorphous powder,
[a]2D0ZK11.2 (cZ0.32, MeOH) The 13C NMR spectrum of
1 showed signals corresponding to 64 carbons, which were
Keywords: Platycosides G1–G3; Triterpenoid saponin; Platycodon grandi-
florum; Campanulaceae; Antiviral activity.
* Corresponding author. Tel.: C852 34062875; fax: C852 34062801;
e-mail: xuhongxi@hkjcicm.org
0040–4020/$ - see front matter q 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2004.12.032

2212
Z. He et al. / Tetrahedron 61 (2005) 2211–2215
Table 1. 1H NMR spectroscopic data (d) for the sugar moieties of 1–3
(400 MHz in pyridine-d5)
H
1
2
3
Glucose (inner)
10
20
4.83 d (7.3)
4.07 t (7.3)
4.80 d (7.6)
4.00 t (7.6)
4.79 d (7.2)
4.03–4.06 m
o
30
40
50
60
4.02–4.04 m
3.82–3.90 m
4.11 dd (3.8, 7.5)
5.01 br d (7.5)
3.82–3.90 m
3.95–3.96 m
3.87–3.87 m
4.10 dd (3.3, 7.4)
4.80 br d (7.1)
3.73–3.75 m
3.88–3.96 m
4.08–4.11 m
5.01–5.15 m
3.88–3.94 m
Glucose (centre)
100
200
300
400
500
600
4.74 d (8.2)
4.02–4.04 m
4.18–4.21 m
4.69 d (7.2)
3.95–3.96 m
)
)
o
4.08–4.16 m
4.74 br d (8.2)
3.82–3.90 m
Glucose (terminal)
4.71 br d (7.1)
3.73–3.75 m
1000
2000
3000
4000
5000
6000
5.03 d (7.7)
4.01 t (7.7)
4.99 d (8.0)
3.95–3.96 m
4.92 d (7.6)
3.88–3.94 m
o
o
4.18–4.21 m
4.08–4.16 m
4.15–4.17 m
4.02–4.04 m
4.65 br d (8.0)
3.82–3.90 m
3.95–3.96 m
4.60 br d (6.8)
3.73–3.75 m
3.88–3.96 m
4.65 br d (7.7)
3.88–3.94 m
Arabinose
1
2
3
4
5
6.43 br s
6.45 br s
6.39 br s
4.48–4.51 m
4.82–3.90 m
4.36–4.38 m
4.46–4.48 m
4.82–3.90 m
4.38–4.45 m
3.87–3.87 m
4.38–4.45 m
4.51–4.55 m
4.38–4.45 m
4.65–4.70 m
3.88–3.94 m
4.23–4.28 m
4.40–4.45 m
4.23–4.28 m
Rhamnose
1
2
5.76 br s
5.73 br s
5.65 br s
o
o
o
o
o
4.02–4.04 m
4.38–4.45 m
3.88–3.94 m
3
4
5
o
4.36–4.38 m
1.71 d (5.2)
4.22–4.28 m
1.61 d (6.0)
4.23–4.28 m
6
Xylose
1.63 (overlap)
1
2
3
4
5.15 d (7.5)
4.02–4.04 m
4.82–3.90 m
4.18–4.21 m
3.48 t (10.1)
5.15 d (7.6)
4.03–4.06 m
3.88–3.94 m
4.15–4.17 m
3.52 t (9.6)
5
Apiose
1
2
3
4
6.26 br s
5.65 br s
—
4.15–4.17 m
4.88 d (7.8)
4.23–4.28 m
sapogenin of 1 was identical with that of 5, and the
monosaccharides were confirmed. Their absolute configur-
ations were determined to be L-rabinose, L-rhamnose,
D-xylose, and D-glucose (ratio 1:1:1:3) by GLC analysis of
the trimethylsilyl (TMSi) derivatives, respectively.16 All the
monosaccharides of 1 were in pyranose forms, as deter-
mined by their 1H and 13C NMR data and 2D NMR
experiments. The b-anomeric configurations of the glucose
and xylose units were determined by their 3JH1,H2 coupling
constants (7.3–8.2 Hz), and arabinose and rhamnose were
determined as the a-configurations by the broad singlet of
their anomeric protons. The sequence of the glycan part
connected to C-3 of the aglycon was deduced from the
following HMBC correlations: H-1000 (d 5.03) of terminal
glucose with C-600 (d 70.1) of centre glucose, H-100 (d 4.74)
of centre glucose with C-60 (d 70.6) of inner glucose, H-10 (d
4.83) of inner glucose with C-3 (d 88.5) of aglycon (see
Fig. 1). The second bisdesmosidic part at C-28 was
established by the following HMBC information: the
correlations between H-1 (d 5.15) of xylose and C-4 (d
83.3), H-1 (d 5.76) of rhamnose and C-2 (d 74.5) of
5
The assignments are based upon DEPT, HMQC, and HMBC experiments.
Overlapped signals are labeled with multiplicity (m). Coupling constants (J
values in Hz) are shown in parentheses.
arabinose, H-1 (d 6.43) of arabinose and C-28 (d 175.7) of
the aglycon (see Fig. 1). On the basis of all the foregoing
evidence, platycoside G1 (1) was elucidated as 3-O-b-D-
glucopyranosyl-(1/6)-b-D-glucopyranosyl-(1/6)-b-D-
glucopyranosyl-2b,3b,16a,23,24-pentahydroxyolean-12-
ene-28-oic acid 28-O-b-D-xylopyranosyl-(1/4)-a-L-
rhamnopyranosyl (1/2)-a-L-arabinopyranoside.
Platycoside G2 (2) was analysed to have the molecular
formula of C59H96O30 by its HRFAB mass spectrum and
13C and DEPT NMR data. The 1H and 13C NMR signals of 2
were assigned by DEPT, TOCSY, HMQC, and HMBC

Z. He et al. / Tetrahedron 61 (2005) 2211–2215
2213
Figure 1. Key HMBC correlations for the sugar sequence of 1 (from H to C).
experiments. The comparison of the 1H and 13C NMR
spectra of 2 with those of 1 clearly revealed that the
sapogenin of 2 was in identical with that of 1, and 2 were
suggested to be a bisdesmosidic glycoside (see Tables 1–3).
The anomeric proton and carbon signals of one xylosyl
group in NMR spectra of 2 where disappeared, and the
chemical shift of C-4 of rhamnose in 2 was shifted upfield
from d 83.3 to 74.0. By comparison with 1, the
configurations of the monosaccharides in 2 were assigned
for b-glucose, a-arabiose, and a-rhamnose, respectively.
The spectral data deduced that compound 2 was a dexylosyl
platycoside G1. Comparing the spectral characteristic of 2
with 1, the absolute configurations were supposed as
L-rabinose, L-rhamnose, and D-glucose. On the basis of
these results, platycoside G2 (2) was identified as 3-O-b-D-
glucopyranosyl-(1/6)-b-D-glucopyranosyl-(1/6)-b-D-
glucopyranosyl-2b,3b,16a,23,24-pentahydroxy-olean-12-
ene-28-oic acid 28-a-L-rhamnopyranosyl-(1/2)-a-L-
arabino-pyranoside.
Platycoside G3 (3) has a molecular formula of C63H102O32
1
determined by HRFAB mass spectrum. The H and 13C
NMR signals of 3 were assigned by DEPT, TOCSY,
1
Table 2. 13C NMR spectroscopic data (d) for the aglycon moieties of 1–3
(100 MHz in pyridine-d5)a
HMQC, and HMBC experiments. Comparing the H and
13C NMR signals of 3 with those of 4, the chemical shift
assignable to H-24 of 3 in the aglycon moiety was shifted
upfield to d 1.45, and the C-24 to d 15.6. Other NMR signals
of 3 were similar to those of 4 (see Tables 1–3). The 1H and
13C NMR spectra suggested that the aglycon of 3 was
polygalacic acid.9 The HMBC experiment of 3 indicated
that the sugar sequence was also a bisdesmosidic glycoside,
and comparison of the NMR spectrum of 3 with that of 4
showed that their glycans were the same. On the basis of the
above results, 3 was concluded to be 3-O-b-D-gluco-
pyranosyl-(1/6)-b-D-glucopyranosyl-polygalacic acid
28-O-b-D-apiofuranosyl-(1/3)-b-D-xylopyranosyl-(1/
4)-a-L-rhamnopyranosyl-(1/2)-a-L-arabinopyranoside.
C
1
2
3
1
2
3
4
5
6
7
8
45.0
68.6
88.5
47.8
47.3
19.1
33.2
40.2
44.7
37.7
23.7
122.8
144.0
42.1
35.8
73.7
49.4
41.3
47.8
30.6
35.8
32.4
63.1
67.1
18.8
17.4
26.7
175.7
33.0
24.4
45.2
70.0
88.8
47.5
47.0
19.2
33.7
40.5
48.1
37.9
24.0
122.6
144.1
42.4
36.0
73.8
49.7
41.5
47.4
30.9
36.0
32.0
63.2
66.0
19.1
17.6
27.0
175.6
33.3
24.8
44.4
69.7
84.5
43.1
47.9
18.7
33.6
40.5
48.0
37.4
24.4
123.2
144.4
42.6
36.5
74.3
49.9
41.6
47.4
31.3
36.3
32.6
66.3
15.6
18.0
17.9
27.6
176.1
33.6
25.2
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
All fractions and isolates, the MeOH extract of P.
grandiflorum were tested for their antiviral activities against
HSV-1, RSV and Flu A. All samples had no activity against
HSV-1 and Flu A. The MeOH extract and fraction F02
showed moderate anti-RSV activity, and saponin 4
exhibited weak anti-RSV activity (see Table 4).
3. Experimental
3.1. General procedures
Optical rotations were measured with a JASCO DIP-370
digital polarimeter. IR absoption spectra were obtained with
a Assignments are based on HMQC, TOCSY and HMBC experiments.

2214
Z. He et al. / Tetrahedron 61 (2005) 2211–2215
Table 3. 13C NMR Spectroscopic data (d) for the sugar moieties of 1–3
(100 MHz in pyridine-d5)a
a Shimadzu IR-450 instrument as a film on KBr Disks.
NMR spectra were obtained with a Bruker 400 spectrometer
operating at 400 MHz for 1H and 100 MHz for 13C,
respectively. Chemical shifts were reported in parts per
million on the d scale with TMS as the internal standard.
FABMS were recorded on VG autospec 3000 system.
Column chromatography was performed with silica gel
(Qingdao Haiyang Chemical Group Co. Ltd, Qingdao,
People’s Republic of China), Diaion HP-20 (Mitsubishi
Chemical, Japan), and ODS (100–200 mesh, Fuji Silysia
Chemical Ltd, Japan). Reversed phase HPLC was carried
out on a Agilent 1100 G1361A preparative pump, equipped
with a Agilent 1100 G1315B Diode-array Detector, and
Alltima C18 (250!22 mm, 10 mm), eluted with CH3CN–
H2O (2:8) at a flow rate of 20 ml/min, with the UV detector
set at 210 nm. GLC was carried out on a Shimadzu GC-7A,
and column: Silicone OV-17 on Uniport HP 2%, 3 mm
i.d.!2.1 m column; column temperature, initial tempera-
ture 140 8C for 16 min and rising 2 8C/min to final 170 8C;
carrier gas, N2, flow rate, 25 ml/min. TLC was performed on
precoated Si gel 60 F254 plates (0.2 mm thick, Merck) with
CHCl3–MeOH–H2O (7:3:1), CHCl3–MeOH–H2O–AcOH
(7:3:1:1), CHCl3–MeOH (9:1), and RP-18 F254 plates
(0.2 mm thick, Merck) with MeOH–H2O (6:4), and spots
were detected by spraying with 10% ethanolic H2SO4
reagent.
C
1
2
3
Glucose (inner)
10
105.8
74.8
78.4
72.0
76.2
70.6
105.9
74.7
78.6
72.5
77.0
70.1
105.7
75.5
78.7
72.2
77.0
70.8
20
30
40
50
60
Glucose (centre)
100
104.7
74.8
78.3
71.2
76.8
70.1
104.8
75.3
78.4
71.2
76.4
70.4
200
300
400
500
600
Glucose (terminal)
1000
105.4
74.9
78.2
70.8
77.4
62.8
105.5
75.1
78.2
71.5
77.6
62.9
105.3
75.5
78.6
70.4
78.0
62.9
2000
3000
4000
5000
6000
Arabinose
1
2
3
4
93.3
74.5
71.7
66.0
62.8
93.4
75.1
70.7
65.5
62.6
93.7
75.5
71.8
66.3
63.2
5
Rhamnose
3.2. Plant material
1
2
3
4
100.8
70.9
72.4
83.3
68.3
18.1
101.4
72.2
72.3
74.0
70.1
18.6
101.4
72.3
73.0
83.9
68.9
18.7
The roots of Platycodon grandiflorum (Jacq.) A. DC were
collected in Hubei Province, PR China, in September 2003.
The raw material was identified by Prof. Zhongzhen Zhao,
Hong Kong Baptist University, Hong Kong, and a voucher
specimen (CMED-0077-1) was deposited in the CMED-
LAB of Hong Kong Jockey Club Institute of Chinese
Medicine.
5
6
Xylose
1
2
3
106.5
75.7
78.0
69.8
67.1
106.8
75.6
85.0
70.1
67.2
4
5
Apiose
3.3. Extraction and isolation
1
2
3
4
5
111.4
78.3
80.7
75.5
65.6
The dried roots (933.8 g) were pulverized and extracted
with MeOH for three times. The MeOH extract was
concentrated in vacuum at 40 8C to give a residue
(255.5 g), which was fractionated by CC on Diaion HP-20
eluting with H2O 18 l, 50% MeOH 6 l, and MeOH 8 l, yield
three fractions (F01-F03). Fraction F02 showed anti-RSV
activity (see Table 4). This fraction was then subjected to
silica gel, ODS CC, and purified by reversed phase HPLC to
yield saponins 1 (123.5 mg, 0.013%), 2 (12.4 mg, 0.001%),
3 (18.0 mg, 0.002%), 4 (239.2 mg, 0.026%), and 5
(429.6 mg, 0.046%).
a Assignments are based on HMQC, TOCSY and HMBC experiments.
Table 4. Anti-RSV activity of the triterpenoid saponins from Platycodon
grandiflorum
Sample
RSVa IC50
(mg/mg)
CC50
(mg/mg)b
SIc
MeOH ext.
Fraction F01
Fraction F02
Fraction F03
1
2
44.1
Inactive
25.0
Inactive
Inactive
Inactive
Inactive
200.0
O200
O200
O200
O200
O200
O200
O200
O200
O200
62.5
4.5
—
8.0
—
—
—
—
1.0
—
24.0
3.3.1. Platycoside G1 (1). White amorphous powder;
[a]2D0ZK11.2 (cZ0.3, MeOH); IR (KBr) nmax: 3400,
2920, 1742, 1644, 1040 cmK1 1H NMR (pyridine-d5,
;
400 MHz): aglycon d 1.01 (3H, s, H-29), 1.08 (3H, s,
H-26), 1.12 (3H, s, H-30), 1.34 (1H, br d, JZ8.6 Hz,
H-15a), 1.38 (3H, s, H-25), 1.41–1.44 (4H, m, H-6, 7a, 19a),
1.55–1.58 (1H, m, H-7b), 1.68 (3H, s, H-27), 1.71–1.81 (2H,
m, H-1a, 15b), 1.91–2.01 (5H, m, H-1b, 5, 11, 9), 2.15 (1H,
br t, JZ9.6 Hz, H-22a), 2.24 (1H, br d, JZ10.0 Hz, H-21a),
2.35 (2H, t, JZ9.6 Hz, H-21b, 22b), 2.77 (1H, t, JZ
13.3 Hz, H-19b), 3.53 (1H, t, JZ13.3 Hz, H-18), 3.82–3.90
(m, H-23a), 4.01–4.04 (m, H-24), 4.46–4.55 (m, H-2, 3),
3
4
5
Inactive
2.6
Ribavirind
a IC50 is the concentration of the sample required to inhibit virus-induced
CPE 50%.
b CC50 is the concentration of the 50% cytotoxic effect.
c SI is selectivity indexZCC50/IC50
.
d Ribavirin, an approved drug for the treatment of RSV infections in
humans.

Z. He et al. / Tetrahedron 61 (2005) 2211–2215
2215
4.66 (1H, d, JZ8.0 Hz, H-23b), 5.26 (1H, br s, H-16), 5.63
(1H, br s, H-12); Other 1H and 13C NMR data: see
Tables 1–3; FAB-MS m/z: 1417 [MCH]C; HRFABMS
m/z: 1417.6490 [MCH]C (Calcd for C64H105O34
1417.6487).
D-xylose (3:1:1:1) by GLC analysis with authentic
monosaccharides.
3.5. Viruses and cells
RSV strain Long, HSV-1 (15577) strain, and Madin Darby
canine kidney (MDCK) cells were obtained from American
Type Culture Collection. Flu A (H3N2) strain was obtained
from Guangzhou, PR China; cytotoxicity assay and
cytopathic effect reduction assay are corresponded with
the reported methods.15
3.3.2. Platycoside G2 (2). White amorphous powder;
[a]2D0ZK50.6 (cZ0.2, MeOH); IR (KBr) nmax: 3400,
2920, 1742, 1646, 1038 cmK1 1H NMR (pyridine-d5,
;
400 MHz): aglycon d 0.94 (3H, s, H-29), 1.01 (3H, s,
H-26), 1.06 (3H, s, H-30), 1.24 (1H, br d, JZ8.0 Hz,
H-15a), 1.34 (3H, s, H-25), 1.39–1.50 (4H, m, H-6, 7a, 19a),
1.63 (3H, s, H-27), 1.68–1.71 (1H, m, H-7b), 1.86–1.94 (7H,
m, H-1, 5, 11, 9), 2.11–2.16 (1H, m H-22a), 2.19–2.33 (3H,
m, H-21, 22b), 2.72 (1H, t, JZ13.3 Hz, H-19b), 3.52 (1H, t,
JZ13.3 Hz, H-18), 3.85–3.87 (m, H- 23a), 3.95–3.96 (m,
H-24), 4.51–4.44 (m, H-2, 3), 4.60 (1H, d, JZ8.0 Hz,
H-23b), 5.18 (1H, br s, H-16), 5.56 (1H, br s, H-12); Other
1H- and 13C NMR data: see Tables 1–3; FAB-MS m/z: 1285
[MCH]C; HRFABMS m/z: 1285.6069 [MCH]C (Calcd
for C59H97O30 1285.6065).
Acknowledgements
We thank Prof. Vincent E. C. Ooi and Ms. Hua Wang,
Department of Biology and Institute of Chinese Medicine,
The Chinese University of Hong Kong, for antiviral assay.
References and notes
3.3.3. Platycoside G3 (3). White amorphous powder,
[a]2D0ZK108 (cZ0.3, MeOH); IR (KBr) nmax: 3400,
1. The State Pharmacopoeia Commission of PR China. In
Pharmacopoeia of the People’s Republic of China; Chemical
Industry: Beijine, 2000; Vol. 1, pp. 225–226.
2920, 1742, 1646, 1038 cmK1 1H NMR (pyridine-d5,
;
400 MHz): aglycon d 0.91 (3H, s, H-29), 1.05 (3H, s,
H-26), 1.06 (3H, s, H-30), 1.25 (3H, s, H-25), 1.27(1H, br d,
JZ8.0 Hz, H-15a), 1.45 (3H, s, H-24), 1.47–1.50 (5H, m,
H-6, 7a, 19a), 1.63 (3H, s, H-27), 1.68–1.76 (1H, m, H-7b),
1.86–2.11 (7H, m, H-1, 5, 9, 11, 15b), 2.20–2.29 (4H, m
H-21, 22), 2.67 (1H, t, JZ13.2 Hz, H-19b), 3.52 (1H, t, JZ
13.3 Hz, H-18), 3.88–3.94 (m, H-23a), 4.40–4.45 (m,
H-2,3), 4.65–4.70 (m, H-23b), 5.15 (1H, br s, H-16), 5.46
(1H, br s, H-12); Other 1H and 13C NMR data: see
Tables 1–3; FAB-MS m/z: 1371 [MCH]C; HRFABMS
m/z: 1371.6429 [MCH]C (calcd for C63H103O32
1371.6432).
2. Oshika, H. Kyoto lgakkai Zasshi 1918, 15, 76–83.
3. Tada, A.; Kaneiwa, Y.; Shoji, J.; Shibata, S. Chem. Pharm.
Bull. 1975, 23, 2965–2972.
4. Ishii, H.; Tori, K.; Tozyo, T.; Yoshimura, Y. Chem. Pharm.
Bull. 1978, 26, 674–677.
5. Ishii, H.; Tori, K.; Tozyo, T.; Yoshimura, Y. J. Chem. Soc.,
Perkin Trans. 1: Org. Bio-Org. Chem. 1981, 1928–1933.
6. Ishii, H.; Tori, K.; Tozyo, T.; Yoshimura, Y. J. Chem. Soc.,
Perkin Trans 1: Org. Bio-Org. Chem. 1984, 661–668.
7. Zhong, Y.; Li, X. G.; Li, S. D.; Xie, J. Yaoxue Tongbao 1986,
21, 71–72.
8. Nikaido, T.; Koike, K.; Mitsunaga, K.; Saeki, T. Nat. Med.
(Tokyo) 1998, 52, 54–59.
3.4. Acid hydrolysis of platycosides G1 (1) and E (5)
9. Nikaido, T.; Koike, K.; Mitsunaga, K.; Saeki, T. Chem.
Pharm. Bull. 1999, 47, 903–904.
Saponins 1 (25 mg) and 5 (30 mg) were heated in 1.5 ml of
1 M HCl (dioxane–H2O, 1:1) at 96 8C for 3 h in a water
bath, respectively, Dioxane was removed and the solution
was extracted with EtOAc (2 ml!3), and removed EtOAc.
The aglycons of 1 and 5 were consistent by comparing with
TLC (silica gel plate, CHCl3–MeOH–H2O–AcOH 7:3:1:1,
visualization by H2SO4 spray and then heated). The aqueous
solution of acid hydrolysis of 1 was neutralized by passing
through an Amberlite MB-3 resin column eluted with water,
then concentrated and dried, and finally treated with
1-(trimethylsilyl)-imidozole at room temperature for 4 h.
After the excess reagent was decomposed with H2O, the
reaction product was extracted with n-hexane (3 ml!2).
The TMSi derivatives of the monosaccharides were
identified as D-glucose, L-arabinose, L-rhamnose and
10. Mitsunaga, K.; Koike, K.; Koshikawa, M.; Takeuchi, H.;
Sacki, T.; Nikaido, T. Nat. Med. (Tokyo) 2000, 54, 148–150.
11. Lee, E. B. Recent Advances in Natural Products Research. In
Proc. 3rd Int. Symp. 1999, 108–116.
12. Kim, Y. S.; Lee, B. E.; Kim, J. J.; Lee, Y. T.; Cho, K. B.;
Chung, Y. C. Yakhak Hoechi 1998, 42, 382–387.
13. Saeki, T.; Nikaido, T. Yakugaku Zasshi 2003, 123, 431–441.
14. Ma, S. C.; He, Z. D.; Deng, X. L.; But, P. P. H.; Ooi, V. E.; Xu,
H. X.; Lee, S. H.; Lee, S. F. Chem. Pharm. Bull. 2001, 49,
1471–1473.
15. Ma, S. C.; Du, J.; But, P. P.; Deng, X. L.; Zhang, Y. W.; Ooi,
V. E.; Xu, H. X.; Lee, S. H.; Lee, S. F. J. Ethnopharm. 2002,
79, 205–211.
16. Kubota, T.; Kitatani, H. Chem. Commun. 1968, 1005–1006.