Two new noroleanane-type triterpenoid saponins from the stems of Stauntonia chinensis

Article abstract of DOI:10.1080/14786419.2018.1470515

Two new noroleanane-type triterpenoid saponins, 3β,20α,24-trihydroxy-29-norolean-12-en-28-oic acid 24-O-β-L-fucopyranosyl-(1→2)-[β-D-xylopyranosyl-(1→3)]-β-D-glucopyranoside (1) and 3β,20α,24-trihydroxy-29-norolean-12-en-28-oic acid 24-O-β-D-glucopyranosyl-(1→2)-[α-L-arabinopyranosyl-(1→3)]-β-D-glucopyranoside (2) were isolated from the stems of Stauntonia chinensis DC., together with three known compounds, brachyantheraoside B₂ (3), eupteleasaponin Ⅷ (4) and fargoside B (5). Their structures were elucidated by spectroscopic and chemical methods. The cytotoxic activities of compounds 1 and 2 were evaluated against five human tumor cell lines (HCT-116, HepG2, BGC-823, NCI-H1650, and A2780). Compounds 1 and 2 showed moderate cytotoxic activities toward the tested cell lines with IC₅₀ values ranging from 12.71 to 32.04?μM.

Full text of DOI:10.1080/14786419.2018.1470515

Natural Product Research
Formerly Natural Product Letters
ISSN: 1478-6419 (Print) 1478-6427 (Online) Journal homepage: http://www.tandfonline.com/loi/gnpl20
Two new noroleanane-type triterpenoid saponins
from the stems of Stauntonia chinensis
Tong-Tong Feng, Hui-Zheng Fu, Yi-Sheng Yang, Zhi-Qiang Zhou, Mian Dai,
Hong-Yu Bi & Dong Wang
To cite this article: Tong-Tong Feng, Hui-Zheng Fu, Yi-Sheng Yang, Zhi-Qiang Zhou, Mian Dai,
Hong-Yu Bi & Dong Wang (2018): Two new noroleanane-type triterpenoid saponins from the stems
of Stauntonia chinensis, Natural Product Research
To link to this article: https://doi.org/10.1080/14786419.2018.1470515
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Natural Product research, 2018
ꢁꢁpꢂ://ꢃꢄi.ꢄꢅg/10.1080/14786419.2018.1470515
ꢀ
Two new noroleanane-type triterpenoid saponins from the
stems of Stauntonia chinensis
a,b†
a†
a
a
a,b
Tong-Tong Feng , Hui-Zheng Fu , Yi-Sheng Yang , Zhi-Qiang Zhou , Mian Dai ,
a,b
a,b
Hong-Yu Bi and Dong Wang
ꢆ
Jiꢆngxi Pꢅꢄvinꢇiꢆꢈ enginꢉꢉꢅing rꢉꢂꢉꢆꢅꢇꢀ cꢉnꢁꢉꢅ fꢄꢅ dꢅꢊg ꢆnꢃ Mꢉꢃiꢇꢆꢈ dꢉviꢇꢉ Qꢊꢆꢈiꢁy, Jiꢆngxi Pꢅꢄvinꢇiꢆꢈ
b
Inꢂꢁiꢁꢊꢁꢉ fꢄꢅ dꢅꢊg cꢄnꢁꢅꢄꢈ, Nꢆnꢇꢀꢆng, cꢀinꢆ; Jiꢆngxi univꢉꢅꢂiꢁy ꢄf tꢅꢆꢃiꢁiꢄnꢆꢈ cꢀinꢉꢂꢉ Mꢉꢃiꢇinꢉ, Nꢆnꢇꢀꢆng,
cꢀinꢆ
ABSTRACT
ARTICLE HISTORY
Two new noroleanane-type triterpenoid saponins, 3β,20α,24-
rꢉꢇꢉivꢉꢃ 8 Fꢉbꢅꢊꢆꢅy 2018
aꢇꢇꢉpꢁꢉꢃ 25 apꢅiꢈ 2018
trihydroxy-29-norolean-12-en-28-oic acid 24-O-β-L-fucopyranosyl-
(
1→2)-[β-D-xylopyranosyl-(1→3)]-β-D-glucopyranoside (1) and
KEYWORDS
3
β,20α,24-trihydroxy-29-norolean-12-en-28-oic
acid 24-O-β-
Stauntonia chinensis;
lꢆꢅꢃizꢆbꢆꢈꢆꢇꢉꢆꢉ;
nꢄꢅꢄꢈꢉꢆnꢆnꢉ-ꢁypꢉ
ꢁꢅiꢁꢉꢅpꢉnꢄiꢃꢂ; ꢇyꢁꢄꢁꢄxiꢇ
ꢆꢇꢁiviꢁy
D-glucopyranosyl-(1→2)-[α-L-arabinopyranosyl-(1→3)]-β-D-
glucopyranoside(2)wereisolatedfromthestemsofStauntoniachinensis
DC., together with three known compounds, brachyantheraoside B2
(3), eupteleasaponin Ⅷ (4) and fargoside B (5). Their structures were
elucidated by spectroscopic and chemical methods. The cytotoxic
activities of compounds 1 and 2 were evaluated against five human
tumor cell lines (HCT-116, HepG2, BGC-823, NCI-H1650, and A2780).
Compounds 1 and 2 showed moderate cytotoxic activities toward
the tested cell lines with IC values ranging from 12.71 to 32.04 μM.
5
0
1
. Introduction
Stauntonia chinensis DC., belonging to the family Lardizabalaceae, grows in southern China,
including Jiangxi, Guangdong, and Guangxi provinces (Shanghai Scientific and Technical
Publishers Shanghai, China 2006). Its stems are used as a traditional Chinese medicine known
as‘Ye Mu Gua’for anti-nociceptive and anti-inflammatory effects (Gao et al. 2008). Previous
CONTACT hꢊi-Zꢀꢉng Fꢊ
tꢀꢉꢂꢉ ꢆꢊꢁꢀꢄꢅꢂ ꢇꢄnꢁꢅibꢊꢁꢉꢃ ꢉqꢊꢆꢈꢈy ꢁꢄ ꢁꢀiꢂ wꢄꢅk.
fꢀzfꢀz620@ꢂꢄꢀꢊ.ꢇꢄm; dꢄng Wꢆng
jxꢃꢇwꢃ@126.ꢇꢄm
†
sꢊppꢈꢉmꢉnꢁꢆꢈ ꢃꢆꢁꢆ fꢄꢅ ꢁꢀiꢂ ꢆꢅꢁiꢇꢈꢉ ꢇꢆn bꢉ ꢆꢇꢇꢉꢂꢂꢉꢃ ꢆꢁ ꢀꢁꢁpꢂ://ꢃꢄi.ꢄꢅg/10.1080/14786419.2018.1470515.
2018 Infꢄꢅmꢆ uK limiꢁꢉꢃ, ꢁꢅꢆꢃing ꢆꢂ tꢆyꢈꢄꢅ & Fꢅꢆnꢇiꢂ Gꢅꢄꢊp
©

2
T.ꢀT. FENG ET AL.
Figure 1. cꢀꢉmiꢇꢆꢈ ꢂꢁꢅꢊꢇꢁꢊꢅꢉꢂ ꢄf ꢇꢄmpꢄꢊnꢃꢂ 1 ꢆnꢃ 2.
investigation on S. chinensis showed its rich content of triterpenoid saponins with anticancer
and anti-inflammatory activities (Wang et al. 1989; Gao et al. 2008). As part of a program to
search for anticancer properties plant resources has led to the isolation of two new
compounds, 3β,20α,24-trihydroxy-29-norolean-12-en-28-oic acid 24-O-β-L-fucopyranosyl-
(1→2)-[β-D-xylopyranosyl-(1→3)]-β-D-glucopyranoside(1), 3β,20α,24-trihydroxy-29-norolean-
12-en-28-oic acid 24-O-β-D-glucopyranosyl-(1→2)-[α-L-arabinopyranosyl-(1→3)]-β-D-
glucopyranoside (2), and three known compounds, brachyantheraoside B (3), eupteleas-
2
aponin Ⅷ (4) and fargoside B (5) from the stems of S. chinensis. Reported herein are the
isolation and structure elucidation and biological activity of these compounds.
2
. Results and discussion
The H O extract of the stems of Stauntonia chinensis DC. was partitioned with CHCl , EtOAc,
2
3
and n-BuOH, successively. The n-BuOH-soluble portion was separated by a combination of
silica gel, repeated medium-pressure liquid chromatography and preparative HPLC to afford
two new compounds (1 and 2) (see Figure 1) and three known compounds 3−5.
Compound 1 was obtained as a white amorphous powder. Its molecular formula was
-
determined as C H O according to HR-ESI-Q-TOF-MS at m/z 913.4851 [M–H] and sup-
4
6
74 18
1
ported by the NMR spectroscopic data. The H NMR spectrum of 1 in pyridine-d showed
5
five tertiary methyls signals at δ 0.80, 0.94, 1.21, 1.53, and 1.59, an olefinic proton at δ 5.54
H
H
(
1H, brs), two oxymethylene protons at δ 4.13 and 4.21 (1H each, d, J = 10.2 Hz). In addition,
H
1
13
the H and C NMR signals for 1 showed three anomeric proton signals at δ 4.85 (1H, d,
H
J = 7.8 Hz), 5.24 (1H, d, J = 7.8 Hz) and 5.62 (1H, d, J = 7.8 Hz) with the corresponding carbon
1
3
resonances at δ 103.9, 105.7 and 103.9, respectively (see Experimental section). The
C
C
NMR spectrum of 1 displayed 46 carbon signals, including a pair of olefinic carbons at δC
22.5 and 144.1, typical for a double bond at C-12(13) in olean-12-ene skeleton (Mehta et
1
al. 2010; Achouri et al. 2017), and a carboxy carbonyl carbon at δ 180.6. However, direct
C
bond and long-range correlation data suggested that one of the geminal methyl groups at

NATURAL PRODUCT RESEARCH
3
C-20 had been replaced by hydroxyl group, forming noroleanolic acid. The NMR data (see
Experimental section) analysis of 1 indicated that it has the same aglycone as 3β,20α,24-
trihydroxy-29-norolean-12-en-28-oic acid (Liu et al. 2017). Acid hydrolysis of 1 with 2 M HCl
afforded D-glucose, L-fucose and D-xylcose, which were identified by GC analysis of their
trimethylsilyl L-cysteine derivatives (Zhang et al. 1996). The β-anomeric configurations for
glucose, xylcose, and fucose were determined from their coupling constants [J = 7.8 Hz (glc),
7.8 Hz (xyl), 7.8 Hz (fuc), respectively].
The linkages of these sugars were determined respectively through their HMBC spectra.
In the HMBC spectrum of 1 (see Figure S1), the long-range correlations of H-1 (δ 5.62) of
H
the fucose with C-2 (δ 79.1) of the glucose, H-1 (δ 5.24) of the xylcose with C-3 (δ 87.8) of
C
H
C
the glucose, H-1 (δ 4.85) of the glucose with C-24 (δ 72.9) of the aglycone, and H-24 (δ
H
C
H
4
.14, 4.21) of the aglycone with C-1 (δ 103.9) of the glucose obtain the linking sequence of
C
the sugar chains. The relative configuration of 1 was indicated by the NOESY spectrum (see
Figure S2), which showed NOE correlations between the following proton pairs: H-3/H-5,
H-3/H -23, and H-18/H -30. On the basis of the above data, compound 1 was elucidated as
3
3
3β,20α,24-trihydroxy-29-norolean-12-en-28-oic acid 24-O-β-L-fucopyranosyl-(1→2)-[β-D-
xylopyranosyl-(1→3)]-β-D-glucopyranoside.
Compound 2 was obtained as a white, amorphous powder, with the molecular formula
−
C H O , as deduced from the [M−H] peak at m/z 929.4777 by HR-ESI-Q-TOF-MS. The NMR
46
74 19
spectroscopic data of compounds 2 and 1 were almost identical except that the fucose and
xylose in 1 was replaced by a glucose (δ 104.2, 79.2, 78.5, 76.1, 70.2, 61.8) and a arabinose
C
(δC 105.6, 75.2, 73.2, 70.0, 68.3) in 2, respectively (see Experimental section). The connectivity
for the sugar residues was further confirmed from the following HMBC correlations (see
Figure S3): Glc-H-1 (δ 4.87)/aglycone-C-24 (δ 72.8), Glc′-H-1 (δ 5.67)/Glc-C-2 (δ 79.4), and
H
C
H
C
Ara-H-1 (δ 5.27)/Glc-C-3 (δ 88.3). Thus, compound 2 was established as 3β,20α,24-trihy-
H
C
droxy-29-norolean-12-en-28-oic acid 24-O-β-D-glucopyranosyl-(1→2)-[α-L-arabinopyranosyl-
(
1→3)]-β-D-glucopyranoside.
Compounds 1 and 2 were evaluated for cytotoxic activities against five human cell lines
HCT-116, HepG2, BGC-823, NCI-H1650, and A2780) with paclitaxel as a positive control (see
(
Table 1). As shown in Table 1, Compounds 1 and 2 showed moderate cytotoxic activities
toward the tested cell lines with IC values ranging from 12.71 to 32.04 μM.
5
0
3
. Experimental
3
.1. General experimental procedures
Melting points were determined on an X-4 digital micro-melting point apparatus without
correction (Beijing Taike Apparatus Co. Ltd., Beijing, China). Optical rotations were measured
on an Autopol IV-T/V (Rudolph Research Analytical, New Jersey, USA). UV spectra were
recorded in MeOH on a Jasco V650 spectrophotometer (JASCO, Inc., Easton, Maryland, USA).
1
13
The H (600 MHz), C (150 MHz), and 2D NMR spectra were recorded on a Bruker AVANCE
600 instrument using TMS (Tetramethylsilane) as an internal reference (Bruker Company,
Ⅲ
Massachusetts, USA). HR-ESI-Q-TOF-MS data were obtained on a Waters Xevo E2Q-Tof mass
spectrometer (Waters, Massachusetts, USA). Medium pressure liquid chromatography (MPLC)
purification was performed on a Büchi chromatography system (Büchi Corp., Flawil,
Switzerland). Preparative HPLC (high performance liquid chromatography) was conducted
with an Angilent Technologies 1200 series instrument with a MWD detector using a

4
T.ꢀT. FENG ET AL.

NATURAL PRODUCT RESEARCH
5
YMC-pack ODS (Octadecylsilyl)-A column (5 μm, 250 × 20 mm). Column chromatography
was performed with silica gel (200–300 mesh, Qingdao Marine Chemical Ltd., Qingdao,
China) and Develosil ODS (50 μm, Nomura Chemical Co. Ltd., Osaka, Japan). TLC (thin layer
chromatography) was carried out with glass precoated with silica gel GF254 plates (Qingdao
Marine Chemical Ltd., Qingdao, China). Spots were visualized under UV light or by spraying
with 10% sulfuric acid in EtOH followed by heating.
3
.2. Plant material
The stems of Stauntonia chinensis DC. were collected from Ganzhou, Jiangxi province of
China, in October 2013. The plant was identified by Prof.. Yong Liu at Jiangxi University of
Traditional Chinese Medicine, China. A voucher specimen (No. 20131022) is deposited in the
Herbarium of Jiangxi Provincial Institute for Drug Control.
3
.3. Extraction and isolation
The stems of Stauntonia chinensis DC. (40 kg) were first cut into 2 cm segments and then
extracted with H O (400 L × 2) at reflux for 2 × 3 h. The aqueous residue partitioned with
2
CHCl (5000 mL × 3), EtOAc (5000 mL × 3), and n-BuOH (8000 mL × 4), successively. After
3
removing solvent, part of n-BuOH-soluble portion (120 g) was fractionated via silica gel
column chromatography, eluting with CHCl −MeOH (2:1), to afford ten fractions A −A on
3
1
10
the basis of TLC analysis. Fraction A (12.2 g) was subjected to silica gel CC and eluted with
4
CHCl −MeOH (2:1 → 1:1, v/v) to afford eight fractions (A − A4–8). Fraction A4–2 (3.9 g) was
3
4–1
chromatographed by MPLC over an ODS column, eluted with CH CN−H O gradient mixtures
3
2
(
25:75 → 35:65, v/v) at a flow rate of 20.0 mL/min to afford fifteen fractions (B −B ) on the
1 15
basis of HPLC analysis. Fraction B (161 mg) was purified by preparative HPLC (YMC-ODS-A
2
5
μm, 250 mm × 20 mm, detection at 210 nm) using 22% CH CN in H O (7 mL/min) contain-
3 2
ing 0.1% TFA (Trifluoroacetic acid) as mobile phase to yield compound 1 (3.4 mg, t 83 min),
R
2
(7.8 mg, t 135 min), and 4 (6.2 mg, t 115 min). Fraction B (68 mg) was subjected to pre-
R R 3
parative HPLC (YMC-ODS-A 5 μm, 250 mm × 20 mm, detection at 210 nm) using 22% CH CN−
3
H O (7 mL/min) containing 0.1% TFA as mobile phase to yield compounds 3 (5.3 mg, t
2
R
1
56 min) and 5 (7.2 mg, t 175 min).
R
3
.3.1. 3β,20α,24-trihydroxy-29-norolean-12-en-28-oic acid 24-O-β-L-fucopyranosyl-
(1→2)-[β-D-xylopyranosyl-(1→3)]-β-D-glucopyranoside (1)
2
0
C H O , white amorphous powder; mp 232−234 °C;[ꢀ] + 16.5 (c 0.24, MeOH); UV (MeOH)
46
74 18
D
λmax (log ε) 206 (2.27) nm; IR νmax 3411, 2929, 2362, 1687, 1447, 1382, 1258, 1205, 1138, 1065,
−1 1
1
007, 941, 841, 802, 723, 632, 569 cm ; H-NMR (C D N, 600 MHz) Aglycone δ : 0.80 (3H, s,
5 5 H
H-25), 0.88 (1H, brd, J = 12.0 Hz, H-5), 0.94 (3H, s, H-26), 1.21 (3H, s, H-27), 1.53 (3H, s, H-23),
.59 (3H, s, H-29), 3.35 (1H, dd, J = 13.8, 3.0 Hz, H-18), 3.47 (1H, dd, J = 9.8, 6.2 Hz, H-3), 4.13
1H, d, J = 10.2 Hz, H-24a), 4.21 (1H, d, J = 10.2 Hz, H-24b), 5.54 (1H, brs, H-12); Sugars: Glc δH:
1
(
3
5
.78 (1H, m, H-5), 4.07 (1H, m, H-4), 4.19 (1H, m, H-3), 4.24 (1H, m, H-2), 4.27 (1H, dd, J = 12.0,
.4 Hz, H-6b), 4.43 (1H, dd, J = 12.0, 1.8 Hz, H-6a), 4.85 (1H, d, J = 7.8 Hz, H-1); Fuc δ : 1.73 (1H,
H
d, J = 6.0 Hz, H-6), 3.68 (1H, m, H-2), 3.83 (1H, m, H-3), 4.15 (1H, m, H-4), 4.23 (1H, m, H-5), 5.62
(
1H, d, J = 7.8 Hz, H-1); Xyl δ : 3.76 (1H, m, H-5b), 4.11 (1H, m, H-2), 4.16 (1H, m, H-3), 4.23 (1H,
H
1
3
m, H-5a), 4.47 (1H, m, H-4), 5.24 (1H, d, J = 7.8 Hz, H-1). C-NMR (C D N, 150 MHz) Aglycone
5
5

6
T.ꢀT. FENG ET AL.
δC: 39.2 (C-1), 28.6 (C-2), 79.6 (C-3), 43.4 (C-4), 56.9 (C-5), 19.6 (C-6), 33.8 (C-7), 40.0 (C-8), 48.3
C-9), 37.5 (C-10), 24.3 (C-11), 122.5 (C-12), 144.1 (C-13), 42.4 (C-14), 28.4 (C-15), 24.2 (C-16),
(
4
1
7.1 (C-17), 44.7 (C-18), 48.4 (C-19), 70.2 (C-20), 36.5 (C-21), 35.4 (C-22), 23.8 (C-23), 72.9 (C-24),
6.0 (C-25), 17.6 (C-26), 26.3 (C-27), 180.6 (C-28), 26.0 (C-29)；Sugars: Glc δ: 103.9 (C-1), 79.1
(C-2), 87.8 (C-3), 69.8 (C-4), 78.5 (C-5), 62.5 (C-6)；Fuc δ: 103.9 (C-1), 73.5 (C-2), 77.1 (C-3), 76.5
(
C-4), 70.0 (C-5), 18.9 (C-6)；Xyl δ: 105.7 (C-1), 75.2 (C-2), 78.9 (C-3), 73.2 (C-4), 68.2 (C-5);
−
HR-ESI-Q-TOF-MS m/z 913.4851 [M − H] (calcd for C H O , 913.4797), 713.4760 [M – H –
4
6
73 18
−
Fuc – 3H O] .
2
3
.3.2. 3β,20α,24-trihydroxy-29-norolean-12-en-28-oic acid 24-O-β-D-
glucopyranosyl-(1→2)-[α-L-arabinopyranosyl-(1→3)]-β-D-glucopyranoside (2)
C H O , white amorphous powder; mp 226−228 °C;[ꢀ] + 20.1 (c 0.18, MeOH); UV (MeOH)
2
0
46
74 19
D
λmax (log ε) 206 (2.20) nm; IR ν 3414, 2931, 1690, 1456, 1380, 1262, 1204, 1078, 937, 909,
max
−1 1
8
39, 800, 722, 631, 561 cm ; H-NMR (C D N, 600 MHz) Aglycone δ : 0.69 (3H, s, H-25), 0.81
5 5 H
(
1H, brd, J = 12.0 Hz, H-5), 0.88 (3H, s, H-26), 1.18 (3H, s, H-27), 1.48 (3H, s, H-23), 1.59 (3H, s,
H-29), 3.34 (1H, dd, J = 11.2, 4.6 Hz, H-18), 3.44 (1H, dd, J = 9.8, 6.0 Hz, H-3), 4.15 (1H, d,
J = 10.2 Hz, H-24a), 4.20 (1H, d, J = 10.2 Hz, H-24b), 5.52 (1H, brs, H-12); Sugars: Glc δ : 3.88
H
(1H, m, H-5), 4.12 (1H, m, H-4), 4.19 (1H, m, H-2), 4.28 (1H, m, H-3), 4.31 (1H, dd, J = 12.0, 5.4 Hz,
H-6b), 4.49 (1H, dd, J = 12.0, 3.0 Hz, H-6a), 4.87 (1H, d, J = 7.8 Hz, H-1); Glc’ δ : 3.55 (1H, m,
H
H-5), 4.01 (1H, m, H-2), 4.26 (1H, m, H-3), 4.28 (1H, m, H-6b), 4.41 (1H, dd, J = 12.0, 1.8 Hz,
H-6a), 4.58 (1H, m, H-4), 5.67 (1H, d, J = 8.4 Hz, H-1); Ara δ : 3.77 (1H, brd, J = 12.0 Hz, H-5b),
H
4
.11 (1H, m, H-3), 4.25 (1H, m, H-4), 4.26 (1H, m, H-5a), 4.50 (1H, m, H-2), 5.27 (1H, d, J = 7.8 Hz,
13
H-1). C-NMR (C D N, 150 MHz) Aglycone δ : 39.1 (C-1), 28.5 (C-2), 80.5 (C-3), 42.9 (C-4), 56.9
5
5
C
(C-5), 19.1 (C-6), 33.7 (C-7), 40.0 (C-8), 48.4 (C-9), 37.3 (C-10), 24.2 (C-11), 122.8 (C-12), 144.6
(C-13), 42.3 (C-14), 28.5 (C-15), 24.1 (C-16), 47.1 (C-17), 44.7 (C-18), 48.4 (C-19), 70.0 (C-20),
36.5 (C-21), 35.4 (C-22), 23.7 (C-23), 72.8 (C-24), 16.4 (C-25), 17.5 (C-26), 26.2 (C-27), 180.3
(
(
(
(
C-28), 26.0 (C-29); Sugars: Glc δ: 102.6 (C-1), 79.4 (C-2), 88.3 (C-3), 69.8 (C-4), 78.6 (C-5), 62.4
C-6)；Glc’δ: 104.2 (C-1), 76.1 (C-2), 79.2 (C-3), 70.2 (C-4), 78.5 (C-5), 61.8 (C-6)；Ara δ: 105.6
−
C-1), 73.2 (C-2), 75.2 (C-3), 70.0 (C-4), 68.3 (C-5); HR-ESI-Q-TOF-MS m/z 929.4777 [M − H]
−
calcd for C H O , 929.4746), 713.4760 [M – H – Glc – 3H O] .
4
6
73 19
2
3
.4. Determination of absolute configurations of the sugar moieties in 1 and 2
Based on the reported procedure (Zhong et al. 2013), each 2 mg of compounds 1 and 2 was
dissolved in 2 M HCl (dioxane:H O, 1:1 v/v) and refluxed for 10 h. After removal of the HCl by
2
evaporation and extraction with EtOAc, the H O extract was again evaporated and dried in
2
vacuo to furnish a monosaccharide residue. The residue was dissolved in pyridine (1 mL) to
which 2 mg L-cysteine methyl ester hydrochloride was added. The mixture was kept at 60 °C
for 2 h, evaporated under an N stream, and dried in vacuo, then trimethylsilylated with
2
N-trimethylsilylimidazole (0.2 mL) for 2 h. The mixture was partitioned between n-hexane
and H O (2 mL each), and the n-hexane extract was analyzed by gas chromatography (GC)
2
under the following conditions: capillary column, HP-5 (30 m × 0.25 mm × 0.25 μm; Dikma);
FID detector with a temperature of 280 °C; injection temperature 250 °C; initial temperature
160 °C, then raised to 280 °C at 5 °C/min, final temperature maintained for 10 min; carrier
gas, N ; carrier gas flow rate 3 mL/min; split ratio 10:1. The standard sugars underwent the
2
same reaction and GC conditions. The retention times of persilylated D-xylose, L-arabinose,

NATURAL PRODUCT RESEARCH
7
D-glucose, and L-fucose were found to be 15.705 min, 16.232 min, 19.035 min, and
9.418 min, respectively.
1
3
.5. Cytotoxicity assay
The cytotoxic activity of compounds 1 and 2 were evaluated using human lung cancer (NCI-
H1650), human gastric cancer (BGC-823), human hepatoma cancer (HepG2), human colon
cancer (HCT-116), and human ovarian cancer (A2780) cell lines. Paclitaxel was used as a
positive control. Following 72 h of continuous treatment of the cells with the samples, the
supernatant was doffed off and 0.1 mL of MTT (0.5 mg/mL in RPM1640) was added after
each well had been carefully washed with RPM1640. The cell growth was measured with an
MTT assay procedure (Carmichael et al. 1987) and the IC50 values were calculated from a
dose-dependent curve from NCI-H1650, BGC-823, HepG2, HCT-116, and A2780 cell lines.
3
.6. Statistical analysis
The results of the cytotoxicity were expressed as means ± SD. Student’s t test was used to
determine statistical comparisons between the data-sets. p < 0.05 was considered to be
significant.
Acknowledgement
We thank Prof Ai-Hong Liu at Center of Analysis AndTesting Nanchang University for NMR measurements.
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding
This study was supported financially by the National Natural Science Foundation of China [NSFC,
grant number 81460589] and the Natural Science Foundation of Jiangxi, China [grant number
20142BAB215086].
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