Isolation and characterization of a new ginsenoside from the fresh root of panax ginseng

Article abstract of DOI:10.3390/molecules15042319

A new saponin, malonylginsenoside Ra3, was isolated from the fresh root of Panax ginseng, along with four known ginsenosides. The new compound was identified as (20S)-protopanaxadiol-3-O-(6-O-malonyl-ss-D-glucopyranosyl(1- 2)-ss-D-glucopyranoside -20-O-ss-D-xylopyranosyl(1?3)-ss-D- glucopyranosyl(1?6)-ss-D-glucopyranoside on the basis of extensive 1D and 2D NMR as well as HRESI-MS spectroscopic data analysis. Copyright

Full text of DOI:10.3390/molecules15042319

Molecules 2010, 15, 2319-2325; doi:10.3390/molecules15042319
OPEN ACCESS
molecules
ISSN 1420-3049
www.mdpi.com/journal/molecules
Article
Isolation and Characterization of a New Ginsenoside from the
Fresh Root of Panax Ginseng
Chang-Chun Ruan 1,2, Zhi Liu 1, Xiang Li 3,4, Xia Liu 2,*, Li-Juan Wang 2, Hong-Yu Pan 4,
Yi-Nan Zheng 2, Guang-Zhi Sun 1, Yan-Sheng Zhang 5 and Lian-Xue Zhang 2,*
1
Institute of Agricultural Modernization, Jilin Agricultural University, Changchun, 130118, China;
E-Mails: ccyuan@yahoo.com (C.C.R.); lzhiiu@126.com (Z.L.); gzsun1967@126.com (G.Z.S.)
2
College of Chinese Medicinal Materials, Jilin Agricultural University, Changchun, 130118, China;
E-Mails: ljwang@yahoo.com(L.J.W.); zhenyinan@tom.com (Y.N.Z.)
3
Agriculture and Agri-Food Canada, Saskatoon Research Center, 107 Science Place, Saskatoon, S7N
0X2, SK, Canada; E-Mail: drxiang@hotmail.com (X.L.)
4
College of Plant Science, Jilin University, Changchun, 130062, China;
E-Mail: panhongyu@jlu.edu.cn (H.Y.P.)
5
Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074, China;
E-Mail: zhangys@wbgcas.cn (Y.S.Z.)
 Authors to whom correspondence should be addressed; E-Mails: jlndzyc@126.com (X.L.);
zh.lianxue@gmail.com (L.X.Z.)
Received: 8 March 2010; in revised form: 23 March 2010 / Accepted: 26 March 2010 /
Published: 30 March 2010
Abstract: A new saponin, malonylginsenoside Ra3, was isolated from the fresh root of
Panax ginseng, along with four known ginsenosides. The new compound was identified as
(20S)-protopanaxadiol-3-O-(6-O-malonyl-β-D-glucopyranosyl(1→2)-β-D-glucopyranoside
-20-O-β-D-xylopyranosyl(1→3)-β-D-glucopyranosyl(1→6)-β-D-glucopyranoside on the
basis of extensive 1D and 2D NMR as well as HRESI-MS spectroscopic data analysis.
Keywords: Panax ginseng; ginsenoside; malonyl-ginsenoside Ra3

Molecules 2010, 15
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1. Introduction
Panax ginseng C.A. Meyer has been used in China for thousands of years as a traditional medicine
and proved to exhibit wide pharmacological properties, such as anti-fatigue, anti-diabetes, as well as
activity in the prevention of cancer and the ageing process [1–4]. The major components contributing
to its pharmacology activities were considered to be the ginsenosides, a group of steroidal saponins.
Around 40 ginsenosides have been isolated and characterized till now, including the recent identified
ginsenosides Ki and Km [5]. Among these known compounds, malonylginsenosides are natural
ginsenosides that exist in both fresh and air-dried ginseng roots and which contain malonyl residues
attached to the glucose units of the corresponding neutral ginsenosides [6]. Kitagawa et al. and
Yamaguchi et al. reported the presence of four acidic ginsenosides both in Asian and American
ginseng [7,8]. Our previous pharmacology results showed that total malonyl-ginsenosides exhibit
hypoglycemic effects on streptozotocin-induced diabetic mice [9]. During our continued studies on
bioactive compounds from Panax ginseng [10–12], a novel ginsenoside, namely malonylginsenoside
Ra3 (compound 1), was isolated from a methanolic extraction of the fresh roots of Panax ginseng. This
paper describes the isolation and structure determination of the new compound 1 (Figure 1).
Figure 1. The structures of the isolated ginsenosides.
2. Results and Discussion
A crude methanolic extract of the fresh roots of Panax ginseng was subjected to open column
chromatography on silica gel and then purified by preparative HPLC, to yield five ginsenosides, one of
which, namely malonylginsenoside Ra3 (compound 1), was new. The other four saponins were
identified as known malonylginsenoside-Rb1 (compound 2), malonylginsenoside-Rb2 (compound 3),
malonylginsenoside-Rc (compound 4) and malonylginsenoside-Rd (compound 5) by comparison of
NMR data with those in the literature [6] and by comparison with authentic sample by ESI-MS, optical
rotation and TLC.
Characterization of compound 1
Compound 1 was obtained as a white amorphous powder and gave a peaks at m/z 1325.4 [M-H]-,
1281 [M-CO2]-, 1239 [M-COCH2COOH]-, 1107 [M-COCH2COOH-xyl]-, 945 [M-COCH2COOH-glc-
xyl]-, 783 [M-COCH2COOH-xyl-2glc-H]-, 621 [M-COCH2COOH-xyl-3glc-H]-, 459 [M-

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COCH2COOH-xyl-4glc-H]-, in the negative ESI-MS, indicating its molecular weight to be 1326. The
molecular formula was determined as C62H102O30 based on HRESI-MS [M+Na]+: m/z 1349.6348
[M+Na]+ (calcd. for C62H102NaO30, 1349.6353). IR (KBr) νmax/cm-1: 3423 cm-1 (OH), 1732 cm-1 (C=O),
1608 (C=C) and 1386 cm-1 (-CH3). Since compound 1 can’t be dissolved in pyridine-d5, we added 0.1
mL of D2O in 0.5 mL of pyridine-d5 as NMR solvent. Ginsenoside m-Rb1 (compound 2) and the
alkaline hydrolysis product of 1, ginsenoside Ra3 (compound 1a) were also dissolved in the same
13
mixture solvent for NMR measurement. Analysis of the C-NMR spectrum (Table 1) and DEPT
experiments, allowed the identification of eight methyl groups and six quaternary carbons.
Table 1. The 13C-NMR data of compounds 1, 2 and 1a. a
1
2
1a
1
2
1a
C-1
C-2
40.0
40.1
39.3
3-Glu
C-1’
27.7
90.9
40.6
57.4
19.4
36.0
40.9
51.0
37.8
31.2
71.0
50.0
52.5
31.8
27.7
52.8
17.2
16.9
85.2
23.3
37.2
24.3
126.7
132.8
26.9
19.0
29.0
17.5
18.3
172.1
27.6
90.7
40.6
57.4
19.4
36.0
41
26.7
89.0
39.6
56.5
18.4
35.1
40.0
50.1
36.8
30.9
70.1
49.3
51.4
30.9
26.6
51.7
16.3
16.0
83.5
22.7
36.1
23.3
126.0
130.8
25.8
17.9
28.1
16.5
17.3
105.5
85.1
78.5
72.2
78.5
63.4
105.8
84.8
78.5
72.2
78.8
63.4
105.0
83.5
78.0
71.6
78.0
62.8
C-3
C-4
C-2’
C-3’
C-4’
C-5’
C-6’
Glu
C-5
C-6
C-7
C-8
C-9
51.1
37.8
31.3
70.9
50.2
52.4
31.9
27.6
52.8
17.2
16.9
85.0
23.3
37.1
24.2
126.8
132.6
26.8
19.0
29.0
17.5
18.3
171.9
C-1”
C-2”
C-3”
C-4”
C-5”
C-6”
20-Glu
C-1’
C-2’
C-3’
C-4’
C-5’
C-6’
Glu
106.3
77.4
79.5
71.6
75.7
66.1
106.5
77.5
79.4
71.7
75.8
66.1
105.9
77.1
79.2
71.6
78.0
62.8
C-10
C-11
C-12
C-13
C-14
C-15
C-16
C-17
C-18
C-19
C-20
C-21
C-22
C-23
C-24
C-25
C-26
C-27
C-28
C-29
C-30
-O-CO
98.7
75.3
78.5
72.2
77.4
70.4
98.8
75.6
78.8
72.2
77.2
72
98.1
74.8
78.0
71.6
77.1
69.6
C-1”
C-2”
C-3”
C-4”
C-5”
C-6”
Xyl
105.5
74.7
88.0
71.7
78.5
63.0
105.6
75.6
78.8
72.2
78.8
63.4
105.0
74.2
87.4
71.3
78.0
62.4
C-1’’’
C-2’’’
106.6
75.7
106.2
75.2

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Table 1. Cont.
CH2
41.9
41.9
C-3’’’
C-4’’’
C-5’’’
77.4
71.2
67.8
77.1
70.8
67.2
COOH
174.6
174.5
a Compounds 1, 1a and 2 were measured in C5N5-d6 (0.5 mL) plus D2O (0.1 mL).
13
The 1H- and C-NMR spectroscopic data of compound 1 were similar to those of ginsenoside-Ra3
[13], except the data attributed to a malonyl group (δH 3.70, δC 172.1, δC 174.6). The malonyl group
was assigned to C3-glc-C-6’’ position by HMBC experiment (Figure 2), which the protons of C3-glc-
H-6’’ showed HMBC correlations with malonyl group (δC 172.1).
Figure 2. Partial HMBC correlation of compound 1.
Malonyl group connection also caused a 2.7 ppm lower-field shift for C3-glc-C-6’’ (δC 66.1) than
seen in ginsenoside-Ra3. Alkaline hydrolysis of compound 1 yield compound 1a, which showed the
structure identical to ginsenoside Ra3 by 1D NMR analysis (Table 1). The absolute configurations of
the sugar moieties were further determined to be β-D-glucose and β-D-xylose by chiral GC analysis.
The 20 position was determined as S conformation due to its similar NMR data with the known
compounds 1a and 2. All the data above led us to identified the structure of 1 as (20S)-protopanaxadiol
3-O-(6-O-malonyl-β-D-glucopyranosyl(1→2)-β-D-glucopyranoside)-20-O-β-D-xylopyranosyl(1→3)-
β-D-glucopyranosyl(1→6)-β-D-glucopyranoside, which we have named malonylginsenoside Ra3.
3. Experimental
3.1. General
1
13
The H- and C-NMR spectra were measured on a Bruker Avance DRX 500 NMR spectrometer,
using TMS as an internal standard. Chemical shifts (δ) are expressed in parts per million (ppm), with
the coupling constants (J) reported in Hertz (Hz). The ESI-MS spectra were recorded on a triple
quadrupole mass spectrometer Quattro (VG Biotech, Altrincham, England) and the HRESI-MS spectra
on a Bruker FT-ICRMS spectrometer. Column chromatographies were carried out with silica gel 60 M
(200–300 mesh), Lichrospher RP-18 (20 μm); TLC was performed with silica gel plates (Macherey-

Molecules 2010, 15
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Nagel, SilG/UV254, 0.20 mm), with spots detected by UV254 and H2SO4 (10%). HPLC were carried out
with a Agilent 1100 system.
3.2. Plant material
The fresh root of Panax ginseng was collected from Fu-Song, Jilin, China, in August 2003, and
identified by one of the authors, Prof. Yi-Nan Zheng. A voucher specimen (ZYC-RS-03-08) has been
deposited in College of Chinese Medicinal Material, Jilin Agricultural University.
3.3. Extraction and isolation
The root of Panax ginseng (10 kg) was extracted five times with MeOH-H2O (4:1), and the extract
was concentrated under reduced pressure at 40 ºC. The residue (~2 kg) obtained was suspended in
water and subjected to D-101 resin column chromatography, using MeOH-H2O (0:1, 3:2) as eluted
solvent to give total-ginsenoside (~300 g). The total-ginsenoside was applied to silica gel column and
eluted with CHCl3-MeOH-H2O (6:4:1) to yield three fractions (F1-F3). Fraction F1 was further
chromatographed on preparative HPLC eluted with gradient CH3CN-H2O (20% to 50%) to give the
known saponins: malonylginsenoside-Rb1 (compound 2, 100 mg), malonylginsenoside-Rb2
(compound 3, 60 mg), malonylginsenoside-Rc (compound 4, 65 mg), malonylginsenoside-Rd
(compound 5, 42 mg) and the new saponin malonylginsenoside Ra3 (compound 1, 40 mg). Compound
1: 1H-NMR (400 MHz, 0.5 mL pyridine-d5  0.1 mL D2O, ppm): δ 0.73 (3H, s, H-19), 0.87 (3H, s, H-
18), 0.95 (3H, s, H-30), 0.98 (3H, s, H-29), 1.17 (3H, s, H-28), 1.63 (3H, s, H-21), 1.65 (3H, s, H-26),
1.69 (3H, s, H-27), 5.29 (1H, t-like, H-24), 5.11 (1H, d, J = 7.2 Hz, C20-glc-H-1’), 4.93 (1H, d, J = 7.2
Hz, C20-glc-H-1’’) 4.85 (1H, d, J = 7.6 Hz, C20-xyl-H-1’’’), 4.81 (1H, d, J = 7.8 Hz, C3-glc-H-1’), 5.19
(1H, d, J = 7.6 Hz,C3-glc-H-1’’); 13C-NMR data, see Table 1.
3.4. Alkaline hydrolysis of compound 1
A solution of 1 (20 mg) in MeOH (3 mL) was treated with 5% KOH-MeOH (0.1 mL) and the whole
mixture was stirred at room temperature (22 ºC) for 30 min [6]. The reaction mixture was neutralized
with cation exchange resin (SP20ss, Resindion S.R.L., Rome, Italy) and filtered. Removal of the
solvent from the filtrate under reduced pressure gave a product which was purified by column
chromatography with reversed-phase silica gel (Zorbax SB-C18) to furnish compound 1a, which was
determined to be identical with an authentic sample [6] by TLC comparison [CHCl3-MeOH-H2O
(65:35:10, lower phase), n-BuOH-AcOH-H2O (4:1:5 upper phase)], IR(KBr), MS and 13C NMR
spectral comparisons. Compound 1a: IR (KBr) νmax / cm-1: 3432, 1728, 1605, 1385, 1078; ESI-MS [-]:
m/z = 1239 [M-H]-, 1107 [M-xyl]-, 945 [M-glc-xyl]-, 783 [M-xyl-2glc-H]-, 621 [M-xyl-3glc-H]-, 459
[M-xyl-4glc-H]-; 1H-NMR (400MHz, 0.5 mL pyridine-d5, ppm): δ 0.70 (3H, s, H-19), 0.84 (3H, s, H-
18), 0.86 (3H, s, H-30), 0.96 (3H, s, H-29), 1.17 (3H, s, H-28), 1.49 (3H, s, H-21), 1.55 (3H, s, H-26),
1.58 (3H, s, H-27), 5.20 (1H, t, H-24), 5.04 (1H, d, J = 7.5 Hz, C20-glc-H-1’), 4.96 (1H, d, J = 7.6 Hz,
C20-glc-H-1’’) 4.83 (1H, d, J = 7.6 Hz, C20-xyl-H-1’’’), 4.80 (1H, d, J = 7.8 Hz, C3-glc-H-1’), 5.26
(1H, d, J = 7.6 Hz, C3-glc-H-1’’); 13C-NMR data, see Table 1.

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3.5. Acid hydrolysis of compound 1
To determine the stereochemistry of sugar moiety, compound 1 (2.0 mg) was refluxed with 6 N HCl
(5 mL) at 100 ºC for 2 h [14,15]. The mixture was extracted with CHCl3 to afford the aglycone, and
the aqueous layer was neutralized with Na2CO3 and filtered. The aqueous layer was dried under
vacuum and the residue was re-dissolved in H2O for sugar analysis by TLC with n-BuOH-AcOH-H2O
(4:1:2) as the solvent. The sample spots were detected by spraying aniline hydrogen phthalate reagent
(100 mL n-BuOH saturated by H2O, 0.96 g aniline and 1.66 g phthalic acid) and heating at 120 ºC. D-
Glucose and D-xylose were used as authentic standards. The absolute configuration of glucose was
further determined by chiral GC analysis using a SatoChrom GC and a 0.25 mm × 25 m Hydrodexb-6-
TBDM chiral capillary column (Macherey-Nagel, Germany). β-D-Glucose and β-D-xylose were used
as an authentic GC standard. The aqueous layer residues mentioned above were re-suspended in
dichloromethane (1 mL), and trifluoroacetic anhydride (50 µL) was added. The mixtures were allowed
to react at room temperature overnight and dried under a stream of nitrogen at room temperature. The
sugar derivatives were separated using the following temperature program: inlet temperature was set at
240 ºC, with hydrogen carrier gas and a 1/20 split, using nitrogen makeup gas. Column temperatures
started at 120 ºC, ramped to 220 ºC at 50 ºC·min–1 and were maintained for 12 min.
4. Conclusion
A phytochemical investigation on the fresh root of Panax ginseng led to the isolation of a new
saponin (20S)-protopanaxadiol 3-O-(6-O-malonyl-β-D-glucopyranosyl(1→2)-β-D-glucopyranoside)-
20-O-β-D-xylopyranosyl(1→3)-β-D-glucopyranosyl(1→6)-β-D-glucopyranoside (1) along with four
known ginsenosides (2–5).
Acknowledgements
We are grateful to Zhi-Wei Deng (Analytical Center, Beijing Normal University) for measuring the
NMR spectra. This work was supported by the grant from National Natural Science Foundation of
China (30971885), Major Program of Transgenic Species Development of Ministry of Agriculture of
China (2009ZX08009-062B) and Key Projects in the National Science & Technology Pillar Program
during the Eleventh Five-Year Plan Period (2009BADB3B05).
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