Three new olean-type triterpenoid saponins from aerial parts of Eclipta prostrata (L.)

Article abstract of DOI:10.1080/14786419.2013.832674

Three new olean-type triterpenoid saponins, namely 3-O-(2-O-acetyl-β- d-glucopyranosyl) oleanolic acid-28-O-(β-d-glucopyranosyl) ester (1), 3-O-(6-O-acetyl-β-d-glucopyranosyl) oleanolic acid-28-O-(β-d- glucopyranosyl) ester (2) and 3-O-(β-d-glucopyranosyl

Full text of DOI:10.1080/14786419.2013.832674

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Natural Product Research: Formerly
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Three new olean-type triterpenoid
saponins from aerial parts of Eclipta
prostrata (L.)
Feng-Min Xia, Chun-Tong Lia, Jun-Ling Mib, Zhi-Jun Wua & Wan-
Sheng Chena
a Department of Pharmacy, Changzheng Hospital, Second Military
Medical University, Shanghai, 200003, P.R. China
b Department of Pharmacy, Chengdu University of Traditional
Chinese Medicine, Chengdu, 611137, P.R. China
Published online: 09 Sep 2013.
To cite this article: Feng-Min Xi, Chun-Tong Li, Jun-Ling Mi, Zhi-Jun Wu & Wan-Sheng Chen
(2014) Three new olean-type triterpenoid saponins from aerial parts of Eclipta prostrata
(L.), Natural Product Research: Formerly Natural Product Letters, 28:1, 35-40, DOI:
10.1080/14786419.2013.832674
To link to this article: http://dx.doi.org/10.1080/14786419.2013.832674
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Natural Product Research, 2014
Vol. 28, No. 1, 35–40, http://dx.doi.org/10.1080/14786419.2013.832674
Three new olean-type triterpenoid saponins from aerial parts of Eclipta
prostrata (L.)
Feng-Min Xia, Chun-Tong Lia, Jun-Ling Mib, Zhi-Jun Wua* and Wan-Sheng Chena
*
aDepartment of Pharmacy, Changzheng Hospital, Second Military Medical University, Shanghai 200003,
P.R. China; bDepartment of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu
611137, P.R. China
(Received 3 February 2013; final version received 6 July 2013)
Three new olean-type triterpenoid saponins, namely 3-O-(2-O-acetyl-b-D-glucopyr-
anosyl) oleanolic acid-28-O-(b-D-glucopyranosyl) ester (1), 3-O-(6-O-acetyl-b-D-
glucopyranosyl) oleanolic acid-28-O-(b-D-glucopyranosyl) ester (2) and 3-O-(b-D-
glucopyranosyl) oleanolic acid-28-O-(6-O-acetyl-b-D-glucopyranosyl) ester (3), were
isolated from the aerial parts of Eclipta prostrata (L.). Their structures were elucidated
based on 1D and 2D NMR and MS spectroscopic data.
Keywords: Eclipta prostrata; chemical constituents; triterpenoid saponins
1. Introduction
Eclipta prostrata (L.) is an annual herbaceous plant, which is one of four species of
genus Eclipta from the family Asteraceae. It is growing widely in the tropical and subtropical
areas of the world, and distributed throughout China, which is known as ‘Mohanlian’.
The aerial parts of E. prostrata are one important traditional Chinese medicine and mainly used
as a tonic for enriching the blood (China Pharmacopoeia Committee 2010). It has attracted a
great deal of attention for its wide range of biological activities, such as antiinflammatory
(Chandra et al. 1987; Arunachalam et al. 2009), antioxidant (Karthikumar et al. 2007),
immunomodulatory (Jayathirthaa & Mishraa 2004), hepatoprotective (Saxena & Singh 1993)
and hair growth promoting properties (Roy et al. 2008). Previous phytochemical investigations
on E. prostrata revealed that it is rich in bioactive natural products, including triterpenes (Yahara
et al. 1994, 1997), coumestans (Wagner et al. 1986), steroids, flavonoids (Sarg et al. 1981),
thiopenes (Singh 1988), polyacetylenes (Singh & Bhargava 1922) and alkaloids (Abdel-Kader
et al. 1998).
As part of an ongoing search for bioactive natural products from traditional folk medicine,
we have conducted a phytochemical investigation on the EtOH extract of the aerial parts of
E. prostrata. This has led to the isolation of three new olean-type triterpenoid saponins (Figure 1),
successively named 3-O-(2-O-acetyl-b-D-glucopyranosyl) oleanolic acid-28-O-(b-D-gluco-
pyranosyl) ester (1), 3-O-(6-O-acetyl-b-D-glucopyranosyl) oleanolic acid-28-O-(b-D-gluco-
pyranosyl) ester (2) and 3-O-(b-D-glucopyranosyl) oleanolic acid-28-O-(6-O-acetyl-b-D-
glucopyranosyl) ester (3). This paper reports the isolation and structure elucidation of the three
compounds.
*Corresponding authors. Email: wuzhijun999@sina.com; chenwanshengsmmu@yahoo.com.cn
q 2013 Taylor & Francis

36
F.-M. Xi et al.
Figure 1. Structures of compounds 1–3.
2. Results and discussion
The 80% EtOH extract of air-dried aerial parts of E. prostrata was suspended in H2O and
partitioned successively with petroleum ether, EtOAc and n-BuOH. The n-BuOH-soluble extract
wassubjectedtocolumnchromatography(CC)andpurifiedbysemi-preparativehigh-performance
liquid chromatography (HPLC) to yield three new terpenoid glycosides (1–3).
Compound 1 was obtained as white amorphous powder. The negative HR-ESI-MS exhibited
pseudo-molecular ion peak at m/z 883.4707 [M þ COOH]2 (calcd for 883.4698, C45H71O17),
consistent with the formula C44H70O15, indicating 108 of unsaturation. The 1H NMR spectrum of
1 showed signals for eight tertiary methyl groups (dH 2.12, 1.81, 1.04, 1.09, 1.02, 0.98, 0.87 and
0.81), an olefinic proton [dH 5.29 (1H, m)] and two anomeric protons [dH 6.28 (1H, d,
J ¼ 7.9 Hz) and 4.89 (1H, d, J ¼ 8.0 Hz)]. The 13C NMR spectrum of 1 exhibited 44 carbon
resonances, classified into 9 quaternary carbons, 16 methines including 12 oxygen-substituted
carbons, 11 methylenes including 2 oxygen-substituted carbons, and 8 methyls. The signals at dC
175.8, 169.9, 144.3, 122.5, 103.7, 95.7 and 21.1 were assigned to a carbonyl carbon (dC 175.8), a
pair of olefinic carbons (dC 144.3, 122.5), two anomeric carbons (dC 103.7, 95.7) and an acetyl
group (dC 169.9, 21.1). These spectroscopic data suggested that 1 was a typical olean-12-ene-
1
type triterpenoid glycoside. The assignment of H and 13C NMR spectroscopic data of 1 (see
Table S1) was based on 1H–1H COSY, HSQC and HMBC experiments. The 1H and 13C NMR
data of 1 were in good agreement with those of eclalbasaponin I (Figure 1, 1a) (Yahara et al.
1994), except for the additional acetyl group (dC 169.9, 21.2) in 1. The position ester linkage of
the acetyl group was confirmed by HMBC spectrum of 1. In the HMBC experiment (Figure S1),
the correlation between H-20 (dH 5.53) and acetyl group (dC 169.9) was observed, indicating that
the acetyl group was attached at the oxygen atom of C-20 of the b-D-glucopyranosyl. The
absolute configurations of glucopyranosyls were further confirmed by acid hydrolysis, followed
by chiral GC–MS analysis of trimethylsilylated derivatives of the resultant monosaccharides.
The relative configurations of 1 were further confirmed by NOESY experiment, which showed
NOE correlations between the following proton pairs: H-3 and H-5, H-23; H-5 and H-9, H-23;
H-9 and H-27; H-16 and H-27; H-18 and H-30; H-24 and H-25; H-25 and H-26. Consequently,
the structure of 1 was elucidated as 3-O-(2-O-acetyl-b-D-glucopyranosyl) oleanolic acid-28-O-
(b-D-glucopyranosyl) ester.
Compound 2 was isolated as white amorphous powder. Its negative HR-ESI-MS showed
pseudo-molecular ion peaks at m/z 883.4714 [M þ COOH]2 (calcd for 883.4698, C45H71O17),
quite close to peak of 1. The same formula C44H70O15 revealed that 1 and 2 were isomers.
1
Comparing the H and 13C NMR spectroscopic data of 2 with 1 (Table S1), both were almost
superimposable, except for some differences of the signals of Glc-I. The different signals of Glc-I in
2 may result from different substitutional positions of acetyl group. This hypothesis was confirmed
unambiguously by the HMBC spectrum of 2. The HMBC experiment showed cross-peaks from

Natural Product Research
37
H-60 (dH 4.89, 4.79) to the acetyl group (dC 170.7). This deduced that the acetyl group was located
at the oxygen atom of C-60 of Glc-I. The absolute configurations of glucopyranosyls were further
verified by acid hydrolysis and chiral GC–MS analysis. Therefore, the structure of 2 is assigned as
3-O-(6-O-acetyl-b-D-glucopyranosyl) oleanolic acid-28-O-(b-D-glucopyranosyl) ester.
Compound 3 was obtained as white amorphous powder. Its molecular formula was
determined as C44H70O15 on the basis of the negative HR-ESI-MS (883.4684 [M þ COOH]2,
1
calcd for 883.4698), indicating that 3 was the isomer of 1 and 2. The H and 13C NMR
spectroscopic data of 3 (Table S1) were quite similar to those of 1a, except that the signals of
Glc-II showed some differences. Further analysis indicated that the major differences of signals
of Glc-II between 3 and 1a could be explained by substitution of acetyl group. HMBC correlation
between H-600 (dH 4.82, 4.73) and the acetyl group (dC 170.5) implied that the acetyl group was
located at the oxygen atom of C-600 of Glc-II in 3. Hence, the structure of 3 is determined to be 3-
O-(b-D-glucopyranosyl) oleanolic acid-28-O-(6-O-acetyl-b-D-glucopyranosyl) ester.
The structures of triterpenoid saponins from E. prostrata contain two types: oleanane-type
and taraxstane-type, such as eclalbasaponin I–VI (Yahara et al. 1994) and eclalbasaponin VII–
X (Yahara et al. 1997). The three new isolated triterpenoid saponins could be classified into
olean-12-ene-type, which is common in the genus Eclipta.
3. Experimental
3.1. General experimental procedures
Optical rotations were measured on a Perkin-Elmer 341 Polarimeter (Waltham, MA, USA). IR
analyses were performed with a NEXUS 470 FT-IR spectrometer (Thermo Nicolet, USA). UV
spectra were recorded on Shimadzu UV/VIS-240 recording spectrophotometer (Shimadzu Co.,
Japan). 1D and 2D NMR spectra were obtained on a Bruker Avance 600 NMR spectrometer
(Bruker Co., Germany). HR-ESI-MS were acquired on an Agilent 6220 TOF LC-MS instrument
(Agilent Technologies, MA, USA). GC–MS was conducted on a Thermo Finnigan Trace GC
apparatus (Thermo Finnigan, CA, USA) using an L-Chirasil-Val column (25 m £ 0.32 mm). CC
was performed by using silica gel (100–200 and 200–300 mesh), ODS (50 mm; YMC (YMC
CO., Ltd, Japan)) and Sephadex LH-20 (40–70 mm) (Amersham Pharmacia Biotech AB,
Uppsala, Sweden). Semi-preparative HPLC isolation was achieved (Agilent Technologies, MA,
USA) with an Agilent 1200 instrument with a refractive index detector, using a C18 column
(250 mm £ 10 mm £ 5 mm, YMC) and eluting with MeOH–H2O at 2.0 mL/min. Precoated
silica gel GF254 and HF254 plates were used for TLC, and zones were visualised under UV light
(254 and 365 nm) or by spraying with 10% H2SO4–EtOH followed by heating.
3.2. Plant material
The plant of E. prostrata was collected from Xianning City, Hubei Province (GPS coordinates: N
29813.4840, E 113850.7610), during July 2011, and identified by Prof. Lian-Na Sun (Department of
Pharmacy, Second Military Medical University, Shanghai, China). A voucher specimen (No.
20110828) was depositedattheDepartmentofPharmacognosy, SecondMilitary Medical University.
3.3. Extraction and isolation
The air-dried aerial parts of E. prostrata (15.0 kg) were extracted three times with 80%
EtOH under reflux. After removal of the solvent by evaporation in vacuum, the residue
was suspended in water (20 L) and then successively partitioned with petroleum ether,
EtOAc and n-BuOH, (3 £ 15 L). The n-BuOH-soluble part (550 g) was fractionated by silica
gel CC eluted with CH2Cl2–MeOH (100:1 ! 50:1 ! 10:1 ! 5:1) to give five fractions

38
F.-M. Xi et al.
(Fr. 1–Fr. 5). Fr. 5 (30 g) was subjected to silica gel CC eluted with CH2Cl2–MeOH–H2O
(50:1:0.1 ! 30:1:0.1 ! 20:1:0.1 ! 10:1:0.1) to afford eight subfractions (Fr. 5.1–Fr. 5.8). Fr.
5.3 (5.1 g) was applied to ODS CC eluted with MeOH–H2O (25% ! 50% ! 75%) to afford
four subfractions (Fr. 5.3.1–Fr. 5.3.4). Fr. 5.3.2 (1.0 g) was purified by semi-preparative HPLC
(45% MeOH–H2O, 2 mL/min) to yield compounds 1 (32.1 mg, tR ¼ 35.4 min) and 2 (48.9 mg,
tR ¼ 38.3 min). Fr. 5.4 (2.5 g) was subjected to Sephadex LH-20 eluted with MeOH–H2O (1:1)
to yield four subfractions (Fr. 5.4.1–Fr. 5.4.4). Fr. 5.4.2 (0.3 g) was purified by semi-preparative
HPLC (40% MeOH–H2O, 2 mL/min) to give compound 3 (5.8 mg, tR ¼ 49.5 min).
3.4. Acid hydrolysis of compounds
Compounds 1, 2 and 3 (each 2.0 mg) were separately heated in 2 M HCl (1 mL) at 1208C for
1.0 h. The mixture was concentrated and the residue was dissolved in 1-trimethylsilyl imidazole
and pyridine (0.2 mL), and the solution was stirred at 608C for 5 min. After drying the solution,
the residue was partitioned between CH2Cl2 and H2O (1 mL, 1:1 v/v). The organic phase was
submitted to GC–MS analysis using an L-Chirasil-Val column (0.32 mm £ 25 m).
Temperatures of the injector and detector were 2008C for both. A temperature gradient system
was used for the oven, starting at 1008C for 1 min and increasing up to 1808C at a rate of 58C/
min. The authentic samples were treated in the same manner with 1-trimethylsilyl imidazole in
pyridine. Only D-glucose was identified by comparing the retention time with those of authentic
D-glucose (tR ¼ 14.70 min) after treatment using the same method.
3.5. Characterisation of compounds
25
Compound 1: amorphous powder; ½aꢀD þ 71:6 (c ¼ 0.5, MeOH); IR (KBr) nmax 3434, 2946,
2881, 1732, 1640, 1464, 1389, 1376, 1308, 1248, 1167, 1077, 1028 cm211; 1H NMR (pyridine-
d5, 600 MHz): d: 0.75 (1H, dd, J ¼ 12.0, 1.0 Hz, H-5), 0.81 (3H, s, H-25), 0.87 (3H, s, H-24),
0.89 (1H, m, H-1b), 0.98 (3H, s, H-29), 1.02 (3H, s, H-30), 1.04 (3H, s, H-23), 1.09 (3H, s,
H-26), 1.23 (1H, m, H-21b), 1.27 (1H, m, H-6b), 1.35 (1H, m, H-19b), 1.35 (1H, m, H-7b), 1.40
(1H, m, H-1a), 1.43 (1H, m, H-6a), 1.57 (1H, m, H-7a), 1.72 (1H, m, H-2b), 1.73 (1H, m, H-9),
1.77 (1H, m, H-15b), 1.81 (3H, s, H-27), 1.94 (2H, m, H-11), 2.07 (1H, m, H-22b), 2.11 (1H, dd,
J ¼ 13.2, 4.0 Hz, H-2a), 2.12 (3H, s, H-Ac), 2.37 (1H, m, H-22a), 2.41 (1H, m, H-21a), 2.53
(1H, dd, J ¼ 12.0, 2.6 Hz, H-15a), 2.77 (1H, t, J ¼ 13.7 Hz, H-19a), 3.22 (1H, dd, J ¼ 11.7,
4.4 Hz, H-3), 3.48 (1H, dd, J ¼ 13.7, 3.9 Hz, H-18), 3.97 (1H, m, H-50), 4.01 (1H, m, H-500), 4.12
(1H, t, J ¼ 8.4 Hz, H-200), 4.18 (1H, m, H-40), 4.24 (1H, m, H-300), 4.26 (1H, m, H-400), 4.27 (1H,
m, H-30), 4.32 (1H, m, H-60b), 4.35 (1H, m, H-600b), 4.42 (1H, m, H-600a), 4.53 (1H, m, H-60a),
4.89 (1H, d, J ¼ 8.0 Hz, H-10), 5.29 (1H, br s, H-16a), 5.53 (1H, t, J ¼ 8.0 Hz, H-20), 5.58 (1H, t,
J ¼ 3.0 Hz, H-12), 6.28 (1H, d, J ¼ 8.4 Hz, H-100). 13C NMR (pyridine-d5, 150 MHz): d: 38.4
(C-1), 26.1 (C-2), 88.9 (C-3), 38.9 (C-4), 55.5 (C-5), 18.3 (C6), 33.2 (C-7), 39.9 (C-8), 47.0
(C-9), 36.8 (C-10), 23.6 (C-11), 122.5 (C-12), 144.3 (C-13), 41.9 (C-14), 35.9 (C-15), 74.2
(C-16), 48.9 (C-17), 41.1 (C-18), 47.0 (C-19), 30.6 (C-20), 35.7 (C-21), 32.0 (C-22), 27.7
(C-23), 16.6 (C-24), 15.4 (C-25), 17.3 (C-26), 27.0 (C-27), 175.8 (C-28), 33.0 (C-29), 24.4
(C-30), 103.7 (C-10), 75.5 (C-20), 76.0 (C-30), 71.6 (C-40), 78.2 (C-50), 62.4 (C-60), 95.7 (C-100),
73.9 (C-200), 78.6 (C-300), 70.9 (C-400), 79.1 (C-500), 62.0 (C-600), 169.9 (C-Ac), 21.1 (C-Ac). HR-
ESI-MS m/z 883.4707 [M þ COOH]2 (calcd for 883.4698, C45H71O17).
25
Compound 2: amorphous powder; ½aꢀD þ 74:8 (c ¼ 0.5, MeOH); IR (KBr) nmax 3436,
1
2945, 2926, 1735, 1637, 1460, 1389, 1370, 1306, 1247, 1168, 1077, 1034 cm21; H NMR
(pyridine-d5, 600 MHz): d: 0.80 (1H, dd, J ¼ 12.1, 0.8 Hz, H-5), 0.87 (3H, s, H-25), 0.93 (3H, s,
H-24), 0.97 (3H, s, H-29), 1.01 (3H, s, H-30), 1.04 (1H,dd, J ¼ 14.1, 3.2 Hz, H-1b), 1.09 (3H, s,
H-26), 1.21 (1H, m, H-21b), 1.24 (3H, s, H-23), 1.25 (1H, m, H-6b), 1.35 (1H, m, H-19b), 1.35

Natural Product Research
39
(1H, m, H-7b), 1.42 (1H, m, H-6a), 1.57 (1H, m, H-7a), 1.58 (1H, m, H-1a), 1.76 (1H, m,
H-15b), 1.78 (1H, m, H-9), 1.81 (3H, s, H-27), 1.86 (1H, m, H-2b), 1.97 (2H, m, H-11), 2.06
(1H, m, H-22b), 2.12 (3H, s, H-Ac), 2.22 (1H, dd, J ¼ 13.3, 3.6 Hz, H-2a), 2.34 (1H, m, H-22a),
2.38 (1H, m, H-21a), 2.52 (1H, dd, J ¼ 11.7, 2.8 Hz, H-15a), 2.77 (1H, t, J ¼ 13.6 Hz, H-19a),
3.22 (1H, dd, J ¼ 11.7, 4.3 Hz, H-3), 3.48 (1H, dd, J ¼ 13.6, 4.0 Hz, H-18), 3.97 (1H, m, H-50),
3.98 (1H, m, H-40), 3.98 (1H, m, H-500), 4.02 (1H, m, H-20), 4.10 (1H, t, J ¼ 8.4 Hz, H-200), 4.18
(1H, m, H-30), 4.23 (1H, m, H-300), 4.26 (1H, m, H-400), 4.33 (1H, dd, J ¼ 11.8, 4.5 Hz, H-600b),
4.41 (1H, dd, J ¼ 11.8, 2.2 Hz, H-600a), 4.79 (1H, dd, J ¼ 11.4, 6.4 Hz, H-60b), 4.83 (1H, d,
J ¼ 7.8 Hz, H-10), 4.89 (1H, dd, J ¼ 11.4, 1.8 Hz, H-60a), 5.28 (1H, br s, H-16a), 5.59 (1H, t,
J ¼ 3.5 Hz, H-12), 6.26 (1H, d, J ¼ 8.4 Hz, H-100). 13C NMR (pyridine-d5, 150 MHz): d: 38.7
(C-1), 26.4 (C-2), 89.1 (C-3), 39.2 (C-4), 55.8 (C-5), 18.3 (C-6), 33.2 (C-7), 39.9 (C-8), 47.0
(C-9), 36.8 (C-10), 23.6 (C-11), 122.5 (C-12), 144.2 (C-13), 41.9 (C-14), 35.8 (C-15), 74.1
(C-16), 48.9 (C-17), 41.1 (C-18), 47.0 (C-19), 30.6 (C-20), 35.7 (C-21), 32.0 (C-22), 27.9
(C-23), 16.7 (C-24), 15.4 (C-25), 17.3 (C-26), 27.0 (C-27), 175.8 (C-28), 33.0 (C-29), 24.4
(C-30), 106.7 (C-10), 75.3 (C-20), 78.2 (C-30), 71.5 (C-40), 74.6 (C-50), 64.6 (C-60), 95.6 (C-100),
73.9 (C-200), 78.5 (C-300), 70.8 (C-400), 79.1 (C-500), 61.9 (C-600), 170.7 (C-Ac), 20.6 (C-Ac). HR-
ESI-MS m/z 883.4714 [M þ COOH]2 (calcd for 883.4698, C45H71O17).
25
Compound 3: amorphous powder; ½aꢀD þ 75:0 (c ¼ 0.2, MeOH); IR (KBr) nmax 3411,
1
2944, 2873, 1732, 1456, 1388, 1363, 1233, 1165, 1076, 1028 cm21; H NMR (pyridine-d5,
600 MHz): d: 0.81 (1H, dd, J ¼ 12.8, 1.0 Hz, H-5), 0.91 (3H, s, H-25), 0.93 (1H,dd, J ¼ 14.1,
3.2 Hz, H-1b), 0.98 (3H, s, H-29), 1.00 (3H, s, H-24), 1.03 (3H, s, H-30), 1.11 (3H, s, H-26), 1.24
(1H, m, H-21b), 1.29 (3H, s, H-23), 1.31 (1H, m, H-6b), 1.34 (1H, m, H-19b), 1.38 (1H, m,
H-7b), 1.45 (1H, m, H-6a), 1.47 (1H, m, H-1a), 1.59 (1H, m, H-7a), 1.77 (1H, m, H-15b), 1.77
(1H, m, H-9), 1.82 (1H, m, H-2b), 1.83 (3H, s, H-27), 1.88 (3H, s, H-Ac), 1.97 (2H, m, H-11),
2.16 (1H, m, H-22b), 2.24 (1H, dd, J ¼ 13.6, 3.6 Hz, H-2a), 2.35 (1H, m, H-22a), 2.40 (1H, m,
H-21a), 2.51 (1H, dd, J ¼ 15.3, 3.1 Hz, H-15a), 2.78 (1H, t, J ¼ 13.6 Hz, H-19a), 3.40 (1H, dd,
J ¼ 11.7, 4.3 Hz, H-3), 3.51 (1H, dd, J ¼ 13.6, 4.5 Hz, H-18), 4.00 (1H, m, H-50), 4.03 (1H, m,
H-20), 4.07 (1H, m, H-400), 4.09 (1H, m, H-500), 4.15 (1H, t, J ¼ 8.4 Hz, H-200), 4.20 (1H, m, H-40),
4.23 (1H, m, H-300), 4.24 (1H, m, H-30), 4.40 (1H, dd, J ¼ 11.5, 5.5 Hz, H-60b), 4.57 (1H, dd,
J ¼ 11.5, 2.3 Hz, H-60a), 4.73 (1H, dd, J ¼ 11.8, 5.3 Hz, H-600b), 4.82 (1H, dd, J ¼ 11.8, 1.7 Hz,
H-600a), 4.93 (1H, d, J ¼ 7.7 Hz, H-10), 5.25 (1H, br s, H-16a), 5.60 (1H, t, J ¼ 3.2 Hz, H-12),
6.25 (1H, d, J ¼ 8.4 Hz, H-100). 13C NMR (pyridine-d5, 150 MHz): d: 38.6 (C-1), 26.3 (C-2), 88.6
(C-3), 39.2 (C-4), 55.6 (C-5), 18.2 (C-6), 33.2 (C-7), 39.8 (C-8), 46.9 (C-9), 36.7 (C-10), 23.5
(C-11), 122.5 (C-12), 144.1 (C-13), 41.8 (C-14), 35.8 (C-15), 74.1 (C-16), 48.9 (C-17), 41.0
(C-18), 46.9 (C-19), 30.5 (C-20), 35.6 (C-21), 31.9 (C-22), 27.9 (C-23), 16.8 (C-24), 15.4
(C-25), 17.3 (C-26), 26.9 (C-27), 175.8 (C-28), 32.9 (C-29), 24.3 (C-30), 106.6 (C-10), 75.5
(C-20), 78.3 (C-30), 71.5 (C-40), 78.4 (C-50), 62.7 (C-60), 95.3 (C-100), 73.7 (C-200), 78.0 (C-300),
70.7 (C-400), 75.8 (C-500), 64.1 (C-600), 170.5 (C-Ac), 20.4 (C-Ac). HR-ESI-MS m/z 883.4684
[M þ COOH]2 (calcd for 883.4698, C45H71O17).
Supplementary material
Supplementary material relating to this article is available online, alongside Table S1 and Figure
S1 and 1D, 2D NMR spectra and HR-ESI-MS, IR data of compounds 1–3.
Acknowledgements
The work was financially supported by the National Natural Science Foundation of the People’s Republic
of China (Grant No. 81274032) and the Scientific Foundation of Shanghai (Grant Nos 11DZ1971301 and
08DZ1971600).

40
F.-M. Xi et al.
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