Phytochemical and antitumor studies on Cynanchum mongolicum (Maxim.) Kom

Article abstract of DOI:10.1080/14786419.2019.1574787

A chemical investigation of Cynanchum mongolicum (Maxim.) Kom. identified 8 compounds. On the basis of spectroscopic data, they were determined to be 3 alkaloids and 5 sinapoyl esters, among which were two previously undescribed compounds (1 and 2). The inhibitory effects of the isolated compounds against four human tumor cell lines were evaluated in vitro by MTT assays, which revealed moderate inhibitory effects with IC₅₀ values < 50 mM, in particularly, three antofine analogues have showed significant antitumor activities with IC₅₀ values < 0.1 mM, which was obviously better than the 5-fluorouracil and potential to be used as cancer drugs.

Full text of DOI:10.1080/14786419.2019.1574787

Natural Product Research
Formerly Natural Product Letters
ISSN: 1478-6419 (Print) 1478-6427 (Online) Journal homepage: https://www.tandfonline.com/loi/gnpl20
Phytochemical and antitumor studies on
Cynanchum mongolicum (Maxim.) Kom
Yong-Cheng Yang, Yan-Ming Wang, Zi-Jian Rong, Li-Na Hong, Qian Zhang,
Jing-Ming Jia & An-Hua Wang
To cite this article: Yong-Cheng Yang, Yan-Ming Wang, Zi-Jian Rong, Li-Na Hong, Qian Zhang,
Jing-Ming Jia & An-Hua Wang (2019): Phytochemical and antitumor studies on Cynanchum
mongolicum (Maxim.) Kom, Natural Product Research, DOI: 10.1080/14786419.2019.1574787
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NATURAL PRODUCT RESEARCH
https://doi.org/10.1080/14786419.2019.1574787
Phytochemical and antitumor studies on Cynanchum
mongolicum (Maxim.) Kom
Yong-Cheng Yang, Yan-Ming Wang, Zi-Jian Rong, Li-Na Hong, Qian Zhang,
Jing-Ming Jia and An-Hua Wang
School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Shenyang,
People’s Republic of China
ABSTRACT
ARTICLE HISTORY
A chemical investigation of Cynanchum mongolicum (Maxim.)
Kom. identified 8 compounds. On the basis of spectroscopic data,
they were determined to be 3 alkaloids and 5 sinapoyl esters,
among which were two previously undescribed compounds (1
and 2). The inhibitory effects of the isolated compounds against
four human tumor cell lines were evaluated in vitro by MTT
assays, which revealed moderate inhibitory effects with IC50 val-
ues < 50 mM, in particularly, three antofine analogues have
showed significant antitumor activities with IC50 values < 0.1 mM,
which was obviously better than the 5-fluorouracil and potential
to be used as cancer drugs.
Received 12 November 2018
Accepted 19 January 2019
KEYWORDS
Cynanchum mongolicum;
benzene derivative;
antofine; cytotox-
icity; antitumor
1. Introduction
Cynanchum mongolicum (Maxim.) Kom., a perennial herbaceous plant in the
Asclepiadaceae family, is mainly distributed in Inner Mongolia autonomous region,
Xinjiang uygur autonomous region and Ningxia hui autonomous region in China (Wu
and Zhou 2006). It has a long history in traditional Chinese Medicine to use for activat-
ing blood circulation, relieving pain, resisting inflammation, removing phlegm and
relieving cough, etc, and is often used in folk to relieve pain, kill insects, reduce heat
and prevent diarrhea, as well as treat cholecystitis. Modern pharmacological studies
have shown that the plant also has obvious inhibitory activities for several tumor cells
(Liu et al. 2003). Previous chemical studies of this plant have revealed the presence of
CONTACT Jing-Ming Jia
jiajingming@163.com; An-Hua Wang
sywanganhua@163.com
Supplemental data for this article can be accessed at https://doi.org/10.1080/14786419.2019.1574787.
ß 2019 Informa UK Limited, trading as Taylor & Francis Group

2
Y. -C. YANG ET AL.
C21 Steroids (Liu et al. 2017; Zhang et al. 2016), antofine (Yang et al. 2015), flavonoids
(Ghada et al. 2008; Mohamed et al. 2008) and benzene derivative (Niu et al. 2015).
In the present investigation of the chemical composition of C. mongolicum, 2 pre-
viously undescribed sinapoyl esters compounds were identified together with 6
known compounds (Figure 1), among them, 4 compounds were obtained from the
genus of Cynanchum for the first time. The structures of the isolated compounds
were determined from various spectroscopic data. Finally, the inhibitory effects of
the isolated compounds against several tumor cells were evaluated in vitro using
MTT assays.
2. Result and discussion
Compound 1 was obtained as a light green amorphous powder, with the molecular
þ
formula C H O as established by the positive HRESIMS m/z 777.2243 [M þ Na]
3
4 42 18
1
(
calcd for C H O Na, 777.2269) (Seeing Figure S7). The H NMR spectrum (Seeing
34 42 18
Figure S2) suggested the presence of four methoxy signals (d 3.81, 6H, s; d 3.79, 6H,
H
H
s) in the upper lot, two groups of aromatic proton signals (d 6.72, 2H, s; d 6.85, 2H,
H
H
s), and two groups of reverse olefin proton signals(d 7.45, 1H, d, J ¼ 16.0 Hz; d 6.23,
H
H
1
H, d, J ¼ 16.0 Hz; d 7.56, 1H, d, J ¼ 16.0 Hz; d 6.43, 1H, d, J ¼ 16.0 Hz) and two
H
H
groups sinapoyl fragments were deduced in the structure, as long as two ketone car-
bons (d 169.1 and d 168.8) observed in the C NMR spectrum (Seeing Figure S3). In
the H- H COSY spectrum (Seeing Figure S6), two different spin-spin systems (H-3/H-4/
13
C
C
1
1
H-5/H-6, H-1’/H-2’/H-3’/H-4’/H-5’/H-6’) were established by the correlations H-3 (dH 4.
Figure 1. Compounds obtained from Cynanchum mongolicum.

NATURAL PRODUCT RESEARCH
3
1
7
2)/H-4 (d 4.18)/H-5 (d 4.01)/H-6 (d 4.56) and H-1’ (d 5.39)/H-2’ (d 3.45)/H-3’ (d 3.
H H H H H H
2)/H-4’ (dH 3.25)/H-5’ (dH 4.17)/H-6’ (dH 4.59). The above-mentioned spectroscopic
data indicated that the aglycon substructure of 1 was similar to (3-O-sinapoyl)-b-D-fruc-
tofuranosyl-(2!1)-(6-O-sinapoyl)-a-D-glucopyranoside (Hokyoung et al. 2000; Jin et al.
2016). In addition, two monosaccharide moieties were determined to be b-D-fructofur-
anose and a-D-glucopyranose by the NMR data with the anomeric proton signal (d 5.
H
3
9, d, J ¼ 3.6 Hz) and an acid hydrolysis experiment with D-glucose and D-fructose as
standard references. Based on the long-range correlations of H-1’ (d 5.39)/C-2(d 105.
H
C
4
), H-6 (dH 4.45)/C-9’’ (d 168.8) and H-6’ (dH 4.59)/C-9’’’ (d 169.1) observed in the
C
C
HMBC data (Seeing Figure S5), the four moieties were connected each other as shown
in the Figure 1. Therefore, the structure of compound 1 ((6-O-sinapoyl)-b-D-fructofura-
nosyl-(2!1)-(6-O-sinapoyl)-a-D-glucopyranoside) was unequivocally characterized
as shown.
Compound 2 was obtained as a light green amorphous powder, with the molecular
þ
formula C H O as established by the positive HRESIMS m/z 1145.3300 [M þ Na]
5
1 62 28
(
calcd for C H O Na, 1145.3325) (Seeing Figure S14). The spectroscopic data of com-
51 62 28
pound 2 indicated that it was similar to 1, except that 2 contains an extra styrene
glycoside group. In the HMBC spectrum of 2 (Seeing Figure S12), a long-range correl-
ation between H-1’’ (d 4.54) and C-3’ (d 85.9) was observed, which determined the
H
C
3-glucopyranosyl-glucopyranose group. The other NMR signals of 2 were similar to
those of 1. The structure of compound 2 was thereby determined to be (6-O-sina-
poyl)-b-D-fructofuranosyl-(2!1)-[(6-O-sinapoyl)-(3!1)-a-D-glucopyranosyl-6-O-sinapoyl]-
a-D-glucopyranoside as shown in the Figure 1.
According to the previous reports, the other compounds were identified to be 6-O-
sinapoyl sucrose (3) (Fabre et al. 2000), 6-O-Feruloylsucrose (4) (Taskova et al. 2010),
lyoniresinol-2a-O-b-D-glucopyranoside (5) (Ohashi et al. 1994), (-)-13aR-6-O-desmethyl-
antofine (6) (Peng and Li 1990), de-6-O-methyl-antofine (7) (Peng and Li 1990) and
(13aR,14R)-14-hydroxyl-7-desmethoxy-antofine (8) (Peng and Li 1990) on the basis of
spectroscopic data and past literature.
The inhibitory effect of isolated compounds against tumor cell lines were investi-
gated using an in vitro bioassay. The new compound 2 and antofine derivatives 6–8
exerted inhibitory effects against four tumor cell lines (Table 1).
Finally, it is worth noting that Cynanchum mongolicum (Maxim.) Kom. is an
accepted name in the genus Cynanchum (family Apocynaceae) just like in www.
Table 1. Inhibition effects on the growth of tumor cells in vitro (IC , lM).
5
0
IC50±SEM(lM)
Comp.
Hep3B
Hela
HCC1806
MCF-7
1
2
3
4
5
6
7
8
>100
66.51 ± 1.304
>100
>100
85.714 ± 4.850
>100
>100
98.837 ± 0.792
>100
>100
>100
7.837 ± 0.763
0.308 ± 0.043
0.115 ± 0.017
5.632 ± 0.435
>100
49.881 ± 4.922
>100
>100
>100
>100
78.674 ± 6.833
0.404 ± 0.135
0.273 ± 0.047
0.105 ± 0.012
32.223 ± 3.257
50.175 ± 5.203
1.852 ± 0.275
0.046 ± 0.007
0.078 ± 0.010
15.990 ± 0.321
44.984 ± 2.653
1.533 ± 0.167
0.611 ± 0.030
0.436 ± 0.045
14.450 ± 2.193
5
-Fu

4
Y. -C. YANG ET AL.
theplantlist.org, while Cynanchum mongolicum (Maximowicz) Hemsley or Cynanchum
hancockianum (Maxim.) Al. Iljinski is a variant name in the Chinese flora. The record
about this plant derives from Tropicos (data supplied on 18 April 2012) which reports
it as an accepted name.
3. Experimental
3.1. General experimental procedures
UV spectra were measured by an Agilent 1260 infinity II UV–vis spectrophotometer
in methanol. HRESIMS data were obtained using an Agilent 1100 series LC/MSD ion
trap mass spectrometer using direction injection. Sugar configurations were detected
by a JAsco OR-4090. NMR spectra were run in CD OD on a Varian Mercury NMR
3
spectrometer. Analytical HPLC data were collected on Agilent 1260 infinity II instru-
ment (Thermo Scientific dionex). Preparative HPLC was given by a Saipuruisi MH-LC
52 instrument with an Elite UV2300 detector and an YMC C18 column
(
250 ꢀ 20 mm, 5 lm). Column chromatographic separations were carried out on silica
gel H-60 (Qingdao Marine Chemical Group Corporation, Qingdao, China),
Macroporous resin D101 (Zhengzhou Qinshi technology Co. Ltd., Zhengzhou, China)
and Sephadex LH-20 (shanghai Yi-He biological technology Co. Ltd., China),
Acetonitrile and Methanol were used of chromatographic grade purchasing from
Sigma-Aldrich in American. All other solvents were used of chemical grade (Yuwang
Chemical Co. Ltd., Shandong, China).
3.2. Plant material
The herb of C. mongolicum were collected in the tengger desert in Inner Mongolia
autonomous region in China and identified by Prof. Liu Yong, JiangXi University of
Chinese Medicine. The specimen was deposited in specimen room of traditional
Chinese Medicine in Shenyang Pharmaceutical University (SPU-2014-0714-16).
3.3. Extraction and isolation
The herb of C. mongolicum (5.5 kg) were crushed and extracted by 95% aqueous
EtOH under Reflux (2 h ꢀ 3). The EtOH extracts (1.1 kg) were fractionally extracted
with petroleum ether, methylene chloride, ethyl acetate, n-butyl alcohol successively
(
10 L ꢀ 3 times). The n-BuOH extract (277 g) were separated by macroporous resin to
get seven EtOH/water fractions (H O fraction, 30% EtOH A/B/C fraction, 60% EtOHA/
2
B fraction, 90% EtOH fraction). The 30% EtOH C fraction and 60% EtOHA/B fraction
(
196 g) was dealed with a silica gel column by elution with CH Cl –MeOH (20:1-1:1)
2 2
in sequence to give fractions A–F. Fraction B was separated in a silica gel column
by elution with PE–EtOAc (100:0-0:100) in sequence to give fractions B1-B6. Fraction
B2 was dealed with preparative HPLC to yield compounds 7 (5.0 mg) and 8
(5.5 mg). Fraction D was separated in a silica gel column by elution with
CH Cl –CH OH (100:0-0:100) in sequence to give fractions D1-D4. Fraction D3 was
2
2
3
dealed with preparative HPLC to get compounds 1 (20.0 mg), 2 (7.3 mg), 4 (4.0 mg)

NATURAL PRODUCT RESEARCH
5
and 5 (9.7 mg). Fraction F was separated in middle pressure liquid chromatography
by elution with CH OH–H O (10:90-100:0) in sequence to give fractions F1-F6.
3
2
Fraction F3 was purified by preparative HPLC to afford compounds 3 (8.4 mg) and
6
(8.4 mg).
3
.3.1. (6-O-sinapoyl)-b-D-fructofuranosyl-(2fi1)-(6-O-sinapoyl)-a-D-glucopyranoside (1)
A light green amorphous powder; UV (CH OH) k
196, 238 and 326nm. HRESIMS m/z
3
max
þ
1
7
3
4
77.2243 [M þ Na] (calcd for C H O Na, 777.2269). H NMR (600 MHz, CD OD), d
34
42 18
3
H
.64(2H, m, H-1), 4.12(1H, m, H-3), 4.18(1H, m, H-4), 4.01(1H, m, H-5), 4.56(1H, m, H-6),
.45(1H, m, H-6), 5.39(1H, d, J ¼ 3.6 Hz, H-1’), 3.45(1H, dd, J ¼ 9.6, 4.0Hz, H-2’), 3.72(1H, t,
J ¼ 9.6 Hz, H-3’), 3.25(1H, m, H-4’), 4.17(1H, m, H-5’), 4.59(1H, m, H-6’), 4.19(1H, m, H-6’),
6
.72(2H, s, H-2’’/6’’), 7.45(1H, d, J ¼ 16.0 Hz, H-7’’), 6.23(1H, d, J ¼ 16.0Hz, H-8’’), 6.85(2H,
s, H-2’’’/6’’’), 7.56(1H, d, J ¼ 16.0Hz, H-7’’’), 6.43(1H, d, J ¼ 16.0 Hz, H-8’’’), 3.81(6H, s, 3’’/5’’-
13
OCH ), 3.79(6H, s, 3’’’/5’’’-OCH ). C NMR (150 MHz, CD OD), d 66.9(C-1), 105.4(C-2),
3
3
3
C
79.1(C-3), 74.7(C-4), 80.8(C-5), 64.1(C-6), 93.1 (C-1’), 73.2(C-2’), 77.1(C-3’), 72.1(C-4’), 72.3(C-
5’), 65.7(C-6’), 126.5(C-1’’), 106.7(C-2’’/6’’), 149.3(C-3’’/5’’), 139.5(C-4’’), 147.4(C-7’’), 115.6(C-
8’’), 168.8(C-9’’), 126.6(C-1’’’), 106.9(C-2’’’/6’’’), 149.3(C-3’’’/5’’’), 139.4(C-4’’’), 149.4(C-7’’’),
115.7(C-8’’’), 169.1(C-9’’’), 56.8(3’’/5’’/3’’’/5’’’- OCH3).
3.3.2. (6-O-sinapoyl)-b-D-fructofuranosyl-(2fi1)-[(6-O-sinapoyl)-(3fi1)-a-D-glucopyr-
anosyl-6-O-sinapoyl]-a-D-glucopyranoside (2)
A light green amorphous powder; UV (CH OH) k
194, 238 and 326nm. HRESIMS m/z
3
max
þ
1
1
3
4
145.3300 [M þ Na] (calcd for C H O Na, 1145.3325). H NMR (600 MHz, CD OD), d
5
1
62 28
3
H
.63(2H, d, J ¼ 5.4 Hz, H-1), 4.12(1H, d, J ¼ 8.0Hz, H-3), 4.18(1H, d, J ¼ 8.0 Hz, H-4),
.01(1H, m, H-5), 4.52(1H, m, H-6), 4.43(1H, m, H-6), 5.48(1H, d, J ¼ 3.6 Hz, H-1’), 3.68(1H,
m, H-2’), 3.93(1H, t, J ¼ 9.2 Hz, H-3’), 3.38(1H, m, H-4’), 4.23(1H, m, H-5’), 4.52(2H, d,
J ¼ 10.0 Hz, H-6’), 4.54(1H, m, H-1’’), 3.33(2H, m, H-2’’), 3.43(1H, m, H-3’’), 3.34(1H, m, H-
4
7
7
7
’’), 3.65(1H, d, J ¼ 3.6 Hz, H-5’’), 4.20(2H, d, J ¼ 10.4Hz, H-6’’), 6.74(2H, m, H-2’’’/6’’’),
.52(1H, d, J ¼ 16.0Hz, H-7’’’), 6.25(1H, d, J ¼ 16.0Hz, H-8’’’), 6.87(2H, m, H-2’’’’/6’’’’),
.48(1H, d, J ¼ 16.0 Hz, H-7’’’’), 6.35(1H, d, J ¼ 16.0Hz, H-8’’’’), 6.86(2H, m, H-2’’’’’/6’’’’’),
.63(1H, d, J ¼ 16.0 Hz, H-7’’’’’), 6.38(1H, d, J ¼ 16.0Hz, H-8’’’’’), 3.83(18H, m, 6 ꢀ OCH ).
3
1
3
C NMR (150 MHz, CD OD), d 64.2(C-1), 105.7(C-2), 79.2(C-3), 77.2(C-4), 80.9(C-5),
3
C
66.8(C-6), 92.8(C-1’), 71.9(C-2’/5’/4’’), 86.9(C-3’), 70.8(C-4’), 65.5(C-6’), 105.5(C-1’’), 75.2(C-
2’’/6’’), 77.5(C-3’’), 75.7(C-5’’), 64.9(C-6’’), 126.7(C-1’’’), 106.8(C-2’’’/6’’’), 149.4(C-3’’’/5’’’),
139.7(C-4’’’), 147.1(C-7’’’), 115.7(C-8’’’), 168.9(C-9’’’), 126.6(C-1’’’’), 106.9(C-2’’’’/6’’’’), 149.4(C-
3’’’’/5’’’’), 139.5(C-4’’’’), 147.3(C-7’’’’), 115.6(C-8’’’’), 168.8(C-9’’’’), 126.5(C-1’’’’’), 107.0(C-2’’’’’/
6’’’’’), 149.3(C-3’’’’’/5’’’’’), 139.4(C-4’’’’’), 147.6(C-7’’’’’), 115.4(C-8’’’’’), 168.7(C-9’’’’’),
56.8/56.9(6 ꢀ OCH3).
3.4. Hydrolysis of new compounds 1 and 2
Two milligram powder of compounds 1 and 2 were dissolved in CH OH (The least
3
ꢁ
amount) and participated in a hydrolysis reaction with 2 M HCl in the 90 C water bath
over 5 h. Then, the reaction liquid was cooled to room temperature and extracted by
dichloromethane three times. The water-layer was evaporated in vacuo by a rotatory

6
Y. -C. YANG ET AL.
evaporator, the residue was dissolved by H O, Subsequently, the H O fraction includ-
2
2
ing saccharide was analyzed by a JAsco OR-4090 detector with comparing to standard
substance glucose and fructose (chromatography column: Shodex Asahipak NH2P-50
4
E, CH CN:H O (3:1), 0.8 mL/min).
3 2
3.5. Cytotoxicity assay
Compounds 1–8 were tested for cytotoxicity against MCF-7, Hela, HCC1806 and
Hep-3B cell lines by means of the MTT method as described (Wang et al. 2014).
4. Conclusions
The present article has obtained 8 compounds from the herb of C. mongolicum,
including two new compounds. On the basis of the structure analysis, the antitumor
effects of these isolated compounds have been evaluated in vitro using MTT assay.
Compared with the positive control 5-fluorouracil, all of compounds displayed moder-
ate antitumor effects.
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding
This work was supported by the National Key R&D Program of China (2017YFC1701200) and the
National Natural Science Foundation of China (No. 81374061); the Program for Innovative
Research Team of the Ministry of Education and Program for Liaoning Innovative Research Team
in University.
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