Chemical constituents of Launaea sarmentosa roots

Cite this paper: Vietnam J. Chem., 2020, 58(5), 637-642 Article 
DOI: 10.1002/vjch.202000057 
637 Wiley Online Library © 2020 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH 
Chemical constituents of Launaea sarmentosa roots 
Le Hong Hanh1, Phung Duc Dung1, Lieu Dieu Huy1, Ngo Thi Thuy Duong1, 
Sumrit Wacharasindhu2, Nguyen Kim Phi Phung1, Huynh Bui Linh Chi3* 
1Department of Chemistry, University of Science, National University HCM City, 
227 Nguyen Van Cu, district 5, Ho Chi Minh City 70000, Viet Nam 
2Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok, Thailand 
3Department of Nature, Dong Nai University, 3 Le Quy Don, Tan Hiep district, Bien Hoa City 
Dong Nai province 76000, Viet Nam 
Submitted April 20, 2020; Accepted May 20, 2020 
Abstract 
By investigating the chemical constituents of the roots of Launaea sarmentosa, collected at Can Gio beach, Can 
Gio district, Ho Chi Minh city, nine compounds were isolated including -amyrin acetate (1), -amyrin acetate (2), 
lupeol acetate (3), -taraksasterol acetate (4), luteolin (5), 4-allyl-2,6-dimethoxyphenol glucopyranoside (6), scorzoside 
(7), ixerisoside D (8) and 9 -hydroxypinoresinol (9). To the best of our knowledge, all compounds were reported in 
other species, but this is the first time they were known in L. sarmentosa. Four compounds (1-4) from the n-hexane 
extract were identified by 4-dimethylaminopyridine-catalyzed benzoylation. Their chemical structures were elucidated 
by means of 1D and 2D NMR, HR-ESI-MS data analysis and compared with those reported in the literature. 
Keywords. Launaea sarmentosa, mixture of triterpenes, DMAP-catalyzed benzoylation. 
1. INTRODUCTION 
Launaea sarmentosa (syn. L. pinnatifida), a creeping 
herb, native to tropical Indian coastlines, belongs to 
family Asteraceae. Islanders of the Indian Ocean 
used the whole plant as a bath decoction to treat skin 
diseases and fish wounds.[1] In the genus Launaea, 
L. sarmentosa has received some scientific studies 
with the total of 8 publications. These studies 
included of pharmacognostical evaluation[1], rapid in 
vitro plant regeneration from leaf,[2] biological assay 
for pain, pyrexia, and inflammation,[3] for 
thrombolytic,[4] antioxidant,[5] antibacterial,[6] 
cytotoxic, anthelmintic,[7] and antifungal.[8] There 
had one report on the chemical constituents from 
seeds of L. sarmentosa including saponin 
triterpenes[8] and none on its roots. 
The 4-dimethylamino pyridine (DMAP) method 
is one of the most fundamental and widely used 
organic transformations for the synthesis of esters. 
In this paper, DMAP derivatization[9] was used to 
change the polarity of each triterpene in the mixture 
in order to separate them easily then the structural 
elucidation was carried out using NMR analysis. 
The isolation of five compounds from the roots of 
Launaea sarmentosa was also reported. 
2. MATERIALS AND METHODS 
2.1. General 
The NMR spectra were measured on a Bruker 
Avance III spectrometer, at 500 MHz for 1H NMR 
and 125 MHz for 13C NMR. The HR–ESI–MS were 
recorded on a MicroOTOF–Q mass and a MALDI-
TOF mass spectrometer. The reaction was 
performed in a 250PSI CEM Discover Microwave 
(USA). IR spectra were acquired on a Nicolet 6700 
FTIR spectrometer (USA). 
2.2. Plant material 
Roots of Launaea sarmentosa (Willd.) Sch. Bip. ex 
Kuntze were collected at Can Gio beach, Ho Chi 
Minh city, Vietnam in December 2017. The 
scientific name of the plant was authenticated by the 
botanist Dr. Dang Van Son, Institute of Tropical 
Biology - Ho Chi Minh City, Viet Nam. 
2.3. Extraction and isolation 
Fresh roots (10.0 kg) were washed, dried and ground 
into powder (2.5 kg), and this powder was extracted 
Vietnam Journal of Chemistry Huynh Bui Linh Chi et al. 
 © 2020 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 638 
by methanol (10×3.5 L) at ambient temperature. The 
filtrated solution was then evaporated to dryness at 
reduced pressure to obtain a residue, consisting of an 
oil (400.0 g) and a solid (160.0 g). The solid residue 
was chromatographed with silica gel and eluted with 
different solvents of increasing polarity to afford 4 
extracts: n-hexane (coded as H, 22.3 g), chloroform 
(C, 19.9 g), ethyl acetate (EA, 20.4 g), and methanol 
(ME, 78.6 g). 
The extract H (22.3 g) was silica gel column 
chromatographed and eluted with n-hexane: 
chloroform (stepwise 99:1, 95:5, 90:10, 1:1, 0:1) to 
give a mixture of triterpene acetates, coded as H1 
including compounds 1-4. The same manner was 
applied on the extract EA (20.4 g) eluted with 
CHCl3–MeOH (stepwise 99:1 to 0:1), and by 
Sephadex LH–20, eluted with CHCl3-MeOH (1:1) to 
give compounds 5 (5.2 mg), 6 (9.0 mg), 
7 (3.0 mg), 8 (1.6 mg), and 9 (2.6 mg). 
Figure 1: Structures of isolated compounds 
The mixture H1: white amorphous powder, 
MALDI-TOF-MS (negative mode) m/z = 409.405 
[C32H52O2–CH3COO]–. The NMR data see table 2. 
Luteolin (5): yellow powder, HR-ESI-MS 
(negative mode) m/z 285.0398 [C15H10O6–H]– 
(calcd. for C15H9O6, 285.0399). 1H-NMR (DMSO-
d6) δH (J in Hz): 12.98 (1H, s, 5-OH), 7.40 (2H, m, 
H-2′, H-6′), 6.88 (1H, d, 8.1, H-5′), 6.66 (1H, s, H-
3), 6.44 (1H, d, 1.6, H-8), 6.18 (1H, d, 1.6, H-6). 
The 13C-NMR (DMSO-d6) C (ppm): 181.6 (C-4), 
164.3 (C-7), 163.8 (C-2), 161.4 (C-5), 157.3 (C-9), 
149.8 (C-4'), 145.8 (C-3'), 121.3 (C-1'), 118.9 (C-6'), 
116.0 (C-5'), 113.3 (C-2'), 103.6 (C-10), 102.8 (C-
3), 98.8 (C-6), and 93.8 (C-8). It was identified by 
the comparison of its NMR with those in the 
literature.[10] 
4-Allyl-2,6-dimethoxyphenol glucopyranoside 
(6): white amorphous powder. HR-ESI-MS (positive 
mode) m/z 379.1366 [C17H24O8+Na]+ (Calcd. for 
C17H24O8Na, 379.1369). The 1H-NMR data (CDCl3) 
δH (J in Hz): 3.86 (3H each, s, 2-OCH3, 
6-OCH3), 6.45 (2H, s, H-3,5), 3.35 (2H, d, 6.5, 
H-  ...  in a larger scale to afford a sufficient 
quantity of H1-OH for the following study. 
The preparation of benzoyl derivative catalyzed 
by DMAP[14] was realized. The compatibility of the 
NMR data of 1a, 2a (table 2) with those reported in 
the literature[15] proposed that 1a was -amyrin 
benzoate and 2a was -amyrin benzoate. 
The mixture of 3a, 4a was also NMR studied, but 
the NMR result could not elucidate their structures 
due to the lack of the corresponding triterpene 
benzoate derivative data in the literature. Therefore, 
3a, 4a was hydrolyzed to afford the mixture of 3b, 
4b. The compatibility of the NMR data of 3b, 4b 
(table 2) with those reported in the literature[16] 
proposed that 3b was lupeol, and 4b was -
taraksasterol. As a result of the above-described 
funtionalization, the mixture H1 was elucidated to 
consist of four O-acetyltriterpenes, including 
 -amyrin acetate (1), -amyrin acetate (2), lupeol 
acetate (3), and -taraksasterol acetate (4). 
Compound 6 was obtained as white amorphous 
powder. Its 1H-NMR spectrum showed signals of 
two methoxy protons at δH 3.86 (2-OCH3, 6-OCH3), 
two aromatic protons at δH 6.45 (H-3, H-5), one 
anomeric proton at δH 4.52 (H-1′), an allyl group at 
δH 3.35 (H-  H-), 5.12 (H-), and six 
signals of the glucosyl moiety. The 13C-NMR 
spectrum displayed 17 carbons, including six 
aromatic carbons at δC 133.6 (C-1), 152.7 (C-2, C-
6), 105.7 (C-3, C-5), 131.1 (C-4), two methoxy 
groups (δC 56.4), one methylene carbon (δC 40.7, C-
 ), one methine carbon (δC 136.9, C-), one olefinic 
carbon (δC 116.6, C-) of the allyl group and a 
glucopyranose moiety at δC 106.8 (C-1'), C 74.3, 
76.9, 70.6, 76.1, 62.8 (C-2′-C-6′). The comparison of 
these spectroscopic data of 6 with those of 4-allyl-
2,6-dimethoxyphenol glucopyranoside in the 
literature[17] showed good compatibility. 
Figure 2: COSY, HMBC and NOESY correlations 
of compounds 7 and 9 
Compound 7 was obtained as a colorless oil. The 
1H-NMR spectrum of 7 (table 1) exhibited signals of 
one methyl group (H 1.21, H-13), four olefinic 
signals H 5.04, 4.85 (H-14a,b), 5.12, 5.02 (H-
15a,b), one anomeric proton signal at (H 4.32, H-
1′), and five proton signals of the glucosyl moiety. 
Vietnam Journal of Chemistry Huynh Bui Linh Chi et al. 
 © 2020 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 640 
The 13C-NMR spectrum of 7 showed resonances of 
21 carbons including one carbonyl carbon (C 181.6, 
C-12), two exomethylene groups (C 112.8, C-14; 
108.5, C-15) and six carbons of a glucose. The 1D, 
2D-NMR (figure 2) data as well as the good 
compatibility of its NMR data with those in the 
literature suggested 7 was scorzoside[18] (table 1). 
Compound 8 was obtained as a colorless oil. 
The NMR data of 8 were closely comparable to 
those of scorzoside (7), except for the absence of 
one methyl group and the presence of an 
exomethylene group in the molecule. The methyl 
proton signal of compound 7 at H 1.21 was replaced 
by two olefinic signals (H 5.64, H-13a; 6.16, 
H-13b) in 8. The 13C-NMR spectrum of 8 showed 21 
carbon signals, in which the methyl group at C 13.5 
(C-13) of 7 was replaced by the exomethylene C-13 
(C 120.8) and the single bond between C-11 (C 
42.9) and C-13 was replaced by the double bond (C 
141.3, C-11; 120.8 C-13). The comparison of the 
NMR data of compound 8 with the reference[19] 
suggested that 8 was ixerisoside D. 
Compound 9 was obtained as a colorless gum. 
The 1H-NMR spectrum exhibited of two 1,3,4-
trisubstituted aryl rings at δH 6.97 (H-2), 6.77 (H-5), 
6.84 (H-6), 7.19 (H-2′), 6.80 (H-5′), 6.89 (H-6′), two 
oxygenated methines at δH 4.86 (H-7), 4.89 (H-7′). 
The two remaining oxygen atoms were parts of the 
five-membered heterocyclic rings. There were one 
hemiacetal proton at δH 5.50 (H-9) and two methoxy 
protons at δH 3.89 (3H each, s, 3-OCH3, 3′-OCH3). 
In addition, 9 showed signals of two methylenes at 
δH 4.23 (H-9′ ), 4.03 (H-9′), and two methine 
protons at δH 2.91 (H-8), 3.16 (H-8′). The 13C-NMR 
spectrum of 9 disclosed 20 carbon signals including 
two oxygenated methines at δC 85.1 (C-7), 88.8 (C-
7′), one hemiacetal methine at δC 102.8 (C-9), two 
methines at δC 54.9, 63.4 (C-8′ and C-8), one 
oxygenated methylene at δC 73.0 (C-9′), two 
methoxy carbons at δC 56.4 (3-OCH3, 3′-OCH3), and 
twelve aromatic carbons at δC 134.4 (C-1), 135.4 (C-
1′), 110.7 (C-2), 111.2 (C-2′), 149.2 (C-3), 149.2 (C-
3′), 147.4 (C-4), 147.2 (C-4′), 115.8 (C-5), 116.2 (C-
5′), 119.8 (C-6), and 120.2 (C-6′). 
The HMBC correlations (figure 2) of the 
methoxy protons 3-OCH3, 3′-OCH3 (δH 3.89) to 
carbon signal at δC 149.2 (C-3 and C-3′) suggested 
that two methoxy groups were linked to two 
aromatic carbons of benzene rings at C-3 and C-3′, 
respectively. The relative configuration of 9 was 
elucidated by the NOESY spectrum (figure 2). The 
NOESY correlations of H-8/H-8′, H-8/H-6, H-8/H2′, 
H8′/H2 suggested the syn-orientations of H-8, H-8′, 
and two benzene rings. On the contrary, the 
correlations of H9/H7, H9/H7′ indicated the syn-
orientations of these protons, which meant that the 
hydroxyl group at C-9 was oriented in the opposite 
side. Based on above evidences as well as the 
positive optical rotation and the good compatibility 
of the NMR data of 9 with those reported in the 
literature,[20] 9 was determined as 9 -
hydroxypinoresinol. 
Table 1: NMR data of 7 and 8 (CD3OD) 
No 
7 8 
δC 
δH 
J (Hz) 
δC 
δH 
J (Hz) 
1 40.3 3.57 m 40.2 3.60 m 
2 31.0 2.05 m 30.8 2.07 m 
 1.85 m 1.86 m 
3 34.0 2.56 m 34.0 2.58 m 
4 154.7 154.2 
5 53.0 2.82 m 52.5 2.91 m 
6 87.9 3.96 t (9.3) 88.2 3.94 t (9.0) 
7 45.5 2.41 m 41.5 3.33 m 
8 38.7 2.46 m 38.0 2.62 dt 
(14.0, 3.0) 
 1.49 m 1.54 m 
9 84.3 4.44 t (3.4) 83.8 4.47 t (3.5) 
10 153.0 152.5 
11 42.9 2.32 m 141.3 
12 181.6 172.4 
13 13.5 1.21 d (6.9) 120.8 5.64 d (3.0) 
6.16 d (3.5) 
14 112.8 5.04 s 113.0 5.06 s 
 4.85 brs 4.84 brs 
15 108.5 5.12 brs 108.6 
5.17 brd 
(1.5) 
 5.02 brs 
5.03 brd 
(1.5) 
1′ 103.7 4.32 d (7.8) 103.6 4.34 d (7.5) 
2′ 75.5 3.24 m 75.3 3.22 m 
3′ 78.4 3.37 m 78.1 3.36 m 
4′ 71.6 3.35 m 71.4 3.35 m 
5′ 78.1 3.18 m 77.9 3.20 m 
6′ 62.7 3.79 dd 
(11.8, 2.6) 
62.5 3.80 dd 
(12.0, 2.5) 
3.68 dd 
(11.8, 4.9) 
 3.68 dd 
(11.8, 4.5) 
4. CONCLUSION 
From roots of Launaea sarmentosa collected at Can 
Gio beach, a mixture of triterpene acetates including 
four compounds: -amyrin acetate (1), -amyrin 
acetate (2), lupeol acetate (3), -taraksasterol acetate 
(4), and five other compounds, luteolin (5), 4-allyl-
2,6-dimethoxyphenol glucopy- ranoside (6), 
scorzoside (7), ixerisoside D (8), and 9 -
hydroxypinoresinol (9) were isolated. Although 
these ones had already been reported in other 
Vietnam Journal of Chemistry Chemical constituents of Launaea sarmentosa roots 
© 2020 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 641 
Table 2: NMR data of the mixture H1 including compounds 1-4 (CDCl3) 
No. 
1 1a 2 2a 3 3b 4 4b 1 2 3 4 
δC (ppm) δH (ppm), J (Hz) 
1 38.5 38.6 38.5 38.4 38.6 38.9 38.6 38.9 
2 23.9 28.2 23.9 28.2 23.9 27.6 23.9 27.6 
3 81.2 81.7 81.2 81.7 81.2 79.2 81.2 79.2 4.49 m 4.49 m 4.49 m 4.49 m 
4 37.9 38.3 37.9 38.3 38.0 39.0 38.0 39.0 
5 55.5 55.5 55.5 55.5 55.6 55.4 55.6 55.4 
6 18.4 18.4 18.4 18.4 18.4 18.5 18.4 18.5 
7 33.1 32.7 32.8 32.7 34.4 34.4 34.4 34.4 
8 40.0 40.2 39.8 38.8 41.0 41.0 41.3 41.2 
9 47.8 47.8 47.8 47.7 50.5 50.6 50.6 50.6 
10 37.2 37.0 37.2 37.0 37.3 37.3 37.3 37.2 
11 23.6 23.4 23.6 23.6 21.1 21.1 21.8 21.8 
12 124.5 124.5 121.8 121.8 25.3 25.3 27.2 27.8 5.12 t 
(5.0) 
5.18 t 
(5.0) 
13 140.0 139.8 145.4 145.4 38.2 38.2 39.4 39.4 
14 42.2 42.2 41.9 41.9 43.0 43.0 42.4 42.5 
15 29.9 28.4 26.3 26.8 27.6 27.6 27.8 27.2 
16 26.8 26.8 27.1 27.1 35.8 35.7 36.5 36.9 
17 34.2 34.9 32.7 32.7 43.2 43.1 34.6 34.5 
18 59.3 59.2 47.4 47.4 48.2 48.4 48.9 48.8 
19 40.2 40.0 47.0 46.9 48.5 48.1 42.5 36.5 
20 39.8 39.8 31.2 31.2 151.1 151.1 140.0 140.0 
21 31.4 31.4 34.9 34.7 30.0 29.9 119.1 119.0 5.26 brd 
(7.0) 
22 41.7 41.7 37.3 37.3 40.6 40.2 36.9 42.3 
23 28.2 28.5 28.2 28.9 28.1 28.1 28.1 28.1 0.88 s 0.88 s 0.84 s 0.84 s 
24 17.1 17.2 16.9 15.7 16.7 15.5 16.5 15.5 0.87 s 0.92 s 0.78 s 0.85 s 
25 15.9 17.7 15.7 17.0 16.2 16.1 16.1 16.3 0.96 s 0.96 s 0.87 s 0.87 s 
26 17.0 17.9 17.0 17.7 16.2 15.9 16.3 16.2 1.03 s 1.03 s 1.04 s 1.03 s 
27 23.4 23.7 26.1 26.3 14.7 14.7 14.9 14.9 1.06 s 1.13 s 0.94 s 0.98 s 
28 28.3 28.9 28.6 28.6 18.2 18.2 21.8 17.9 0.80 s 0.83 s 0.79 s 0.73 s 
29 17.7 18.4 23.7 33.5 109.5 109.5 17.9 22.7 0.80 s 0.90 s 4.61 m 1.01 d 
(7.5) 
30 21.5 21.6 33.5 23.8 19.5 19.5 22.7 21.8 0.91 d 
(4.0) 
0.88 s 1.68 brs 1.63 brs 
C=O 171.1 166.4 171.1 166.4 171.1 - 171.1 - 
H3C-
CO 
21.5 - 21.5 - 21.5 - 21.5 - 2.04 s 2.04 s 2.04 s 2.04 s 
1′ - 131.1 - 131.1 - - - - 
2′, 6′ - 129.7 - 129.7 - - - - 
3′, 5′ - 128.5 - 128.5 - - - - 
4′ - 132.9 - 132.9 - - - - 
a: Benzoyl derivatives. b: Hydrolyzed product of benzoyl derivatives. 
1, 2, 3, 4: Data were individually selected from that of the mixture H1. 
species, they were known in L. sarmentosa for the 
first time. 
Acknowledgments. Le Hong Hanh was very 
thankful to Chulalongkorn University, Thailand with 
one semester scholarship program for the students 
from ASEAN Countries (from August to December, 
2019) for the structural elucidation of the mixture 
H1. 
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Corresponding author: Huynh Bui Linh Chi 
Dong Nai University 
3 Le Quy Don, Tan Hiep district, Bien Hoa City 
Dong Nai province 76000, Viet Nam 
E-mail: hainhanchi@yahoo.com.vn.