Phytochemical investigation of Eurycoma longifolia roots collected in Gia Lai province, Viet Nam

Cite this paper: Vietnam J. Chem., 2020, 58(5), 705-710 Article 
DOI: 10.1002/vjch.202000126 
705 Wiley Online Library © 2020 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH 
Phytochemical investigation of Eurycoma longifolia roots collected in 
Gia Lai province, Viet Nam 
Vo Khanh Ha
1
, Truong Thi Minh Hanh
2
, Pham Cam Nam
2
, Giang Thi Kim Lien
3
, 
Mai Thi Phuong Chi
4
, Tran Thi Phuong Thao
5,6*
1
Department of Science and Technology, Quality Assurance and Testing Centre 2, 
2 Ngo Quyen street, Da Nang City 50000, Viet Nam
2
University of Science and Technology, The University of Da Nang, 
54 Nguyen Luong Bang street, Da Nang City 50000, Viet Nam
3
The University of Da Nang, 41 Le Duan street, Da Nang City 50000, Viet Nam 
4
University of Technology and Education, The University of Da Nang, 
48 Cao Thang street, Da Nang City 50000, Viet Nam 
5
Institute of Chemistry, Vietnam Academy of Science and Technology (VAST), 
18 Hoang Quoc Viet road, Cau Giay district, Hanoi 10000, Viet Nam 
6
Graduate University of Science and Technology, VAST, 
18 Hoang Quoc Viet road, Cau Giay district, Hanoi 10000, Viet Nam 
Received July 24, 2020; Accepted August 7, 2020 
Abstract 
From the roots of Eurycoma longifolia, seven compounds including β-carboline-2N-oxide-1-propionic acid (1), 
9,10-dimethoxycanthin-6-one (2), β-carboline-1-propionic acid (3), infractine (4), eurylene (5), eurycomanone (6), 
14,15-β-hydroxyklaineanol (7) were isolated. Their structures were determined by means of spectroscopic methods 
(UV, IR, HR-ESIMS, 1D and 2D NMR). Compound (1) has been isolated for the first time from nature and compound 
(4) has been isolated for the first time from Eurycoma longifolia. 
Keywords. Eurycoma longifolia, β-carboline-2N-oxide-1-propionic acid, β-carboline-1-propionic acid, 9,10-
dimethoxycanthin-6-one, infractin, eurylene, eurycomanone, 14,15-β-hydroxyklaineanol. 
1. INTRODUCTION 
Eurycoma longifolia Jack (Simaroubaceae) is a 
traditional medicine distributed in Southeast Asia. In 
Vietnam, it is found in the middle and Southeast of 
Vietnam.
[1]
 All the parts of this plant (leaves, barks, 
fruits and roots) can be used in folk medicine. 
Especially the roots of Eurycoma longifolia are very 
common used in Vietnamese traditional medicine to 
treat poor blood, dyspepsya, osteoarthritis, colds, 
fevers and poisoning diseases.
[1]
 Phytochemistry 
study of this plant led to the isolation of many 
bioactive compounds such as quassinoid, 
triterpenoid, alkaloid, coumarin, squalene and 
biphenyl-neo-lignan.
[2] 
It has been reported that this 
plant has many biological activities, such as 
anticancer,
[3]
 antiinflammatory,
[4]
 hypoglycemic,
[5] 
anti-gout activity...
[6]
From Eurycoma longifolia roots collected in Gialai 
province, Vietnam, one squalene derivative (5), four 
β-carboline alkaloids (1-4) and two quassinoids (6, 
7) were identified. Compound 4 (infractin) has been 
isolated for the first time from this plant and 
compound 1 (β-carboline-2N-oxide-1-propionic 
acid) has been isolated for the first time from nature. 
Their structures were elucidated by analysis of 
spectral data and comparison with the published 
data. 
2. MATERIAL AND METHODS 
2.1. Plant materials 
Eurycoma longifolia roots were collected in Gia Lai 
province, Vietnam in April 2018 and identified by 
Mr. Nguyen The Anh (Institute of Chemistry, 
Vietnam Journal of Chemistry Tran Thi Phuong Thao et al. 
© 2020 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 706 
VAST). A voucher specimen (EL01) was deposited 
in Institute of Chemistry, Vietnam Academy of 
Science and Technology, 18 Hoang Quoc Viet, Cau 
Giay Distr., Hanoi, Viet Nam. 
2.2. General experiment procedures 
NMR spectra were measured on a Bruker Avance 
500 spectrometer. HR-ESI-MS spectra were 
recorded on SCEIX X500R QTOF (USA). ESI-MS 
spectra were obtained from Agilent 1100 mass 
spectrometer. Silica gel (230-400 mesh), Sephadex 
LH-20, diaion HP-20 using for column 
chromatography were purchased from Merck 
(Darmstadt, Germany). RP-18 resins (30-50 μm) 
were purchased from Fujisilica Chemical Ltd, Japan. 
Precoated silica gel 60 and RP-18 F254S plates were 
used for TLC. 
2.3. Extraction and isolation 
- Isolation of alkaloid compounds: 
The dried powder of the roots of Eurycoma 
longifolia (1.0 kg) was boilt in water (2.5 l) at 70 
o
C 
for 3x5h. The solutions were combined, filtered and 
removed water under reduced presssure to obtain the 
residue (40 g). The water extract (40 g) was 
chromatographed on a Dianion HP-20 column, 
eluting with MeOH in H2O (20; 50; 80 and 100 %, 
respectively) to obtain 15 fractions (Fr.1-15). 
Fraction Fr.8 (1.7 g) was chromatographed on a 
silica gel column, eluting with a gradient of 
DCM/MeOH (98:2, 95:5, 9:1, 8:2, 1:1, v/v) to give 
19 fractions (Fr.8.1-Fr.8.19). Fr.8.12 was subjected 
to a RP-18 column (MeOH/H2O 7:3) to afford 7 
fractions (Fr.8.12A-H). Compound 1 (5.0 mg) and 3 
(10 mg) were obtained from Fr.8.12C using a 
Sephadex column (100 % MeOH). Fraction Fr.3 (17 
g) was separated by silica gel CC, eluting with 
DCM/MeOH (98/2, v/v) to afford 15 subfractions 
(Fr.3.1-15). Fraction Fr.3.2 was subjected to a silica 
gel column (DCM/MeOH 95:5) followed by 
Sephadex column (100 % MeOH) to afford 
compound 2 (20 mg). Compound 4 (4 mg) was 
purified from Fr. 3.6 (120 mg) by column 
chromatography on silica gel (DCM/MeOH 95:5) 
and Sephadex LH-20 column (MeOH 100 %). 
- Isolation of non-ankaloid compounds: 
The dried powder of the roots of Eurycoma 
longifolia (2 kg) was extracted with EtOH/H2O 
(3x3h) at 50 
o
C. The solvent was evaporated to 
afford the EtOH extract (150 g) which was then 
added water and successively extracted with n-
hexane and ethyl acetate. The solvent was removed 
under reduced pressure to o ... J = 5.5, H-3), 7.94 (1H, d, J = 5.5, H-4), 8.19 
(1H, d, J = 8.0, H-5), 7.23 (1H, dd, J = 8.0, 1.5, H-
6), 7.53 (1H, ddd, J = 8.0, 6.8, 1.0, H-7), 7.59 (1H, 
d, J = 8.0, H-8), together with two methylene groups 
at δH 2.87 (1H, t, J = 7.5, H-1’) and 3.35 (1H, t, J = 
7.5, H-2’). The 13C NMR spectrum of 3 indicated 14 
carbons including one carboxylic acid at δC 174.10 
(C-3’), 11 aromatic carbons at δC 112.79-144.04, 
two methylene carbons at δC 31.31 (C-1’), and 28.04 
(C-2’). Analysis of MS, 1H and 13C NMR spectra of 
3 revealed that this compound was a β-carboline- 
derivative with propionic acid unit substituted at C-
1. By comparing the NMR data of 3 with those 
reported in the literatures,
[8]
 compound 3 was 
identified as β-carboline-1-propionic acid. This 
compound was isolated previously from E. 
longifolia. 
 Compound 1 was isolated as yellow powder. Its 
molecular formular (C14H12N2O3) contained one 
oxygen atom more than 3, which was establishing 
from molecular ion peak at m/z 255.0775 [M-H]
-
(calculated for C14H11N2O3 255.0770) in HR-ESIMS 
spectrum. The 
13
C NMR data of 1 showed the 
signals similar to those of 3, except some much 
downfield chemical shifts (3-4 ppm) of some carbon 
signals at δC 147.11 (C-1), 36.65 (C-1’), 31.26 (C-
2’) and 177.87 (C-3’, COOH) (table 1). Besides, the 
signals of aromatic protons of 1 also shifted to 
downfield (δH 8.00-9.00 ppm), comparing with those 
in compound 3 (table 1). This was due to the effect 
of the N-oxide group. The analysis of MS, 
1
H and 
13
C NMR spectra of 1 revealed that this compound 
was a β-carboline-N-oxide derivative with an unit of 
propionic acid substituted at C-1. The structure of 1 
was further confirmed by HSQC and HMBC 
spectra. The HMBC correlation between H-3 (δH 
9.00)/ C-1 (δC 147.11), C-4 (δC 112.39), H-5 (δH 
8.97)/C- 6 (δC 127.45), C-10 (δC 126.91, H-4 (δH 
8.68)/C-11 (δC 121.12), H-6 (δH 8.28)/C-5 (δC 
118.80), C-7 (δC 121.46) proved the structure of the 
aromatic ring of β-carboline. Morever, the 
correlation of H-1’ (δH 3.36), H-2’ (δH 4.18)/C-1 (δC 
147.11), C-3’ (δC 177.87) confirmed the attachment 
of a propionic acid group to C-1. From all evidences 
above and by comparison with compound 3,
[7]
 it is 
concluded that compound 1 is β-carboline-2N-oxide-
1-propionic acid (figure 1). As the best of our 
knowledge, this is the first time compound 1 has 
been isolated from nature. This compound was 
synthesized from β-carboline-1-propionic acid and 
commercially available. However, the NMR data of 
this compound has not yet been reported. Herein, we 
report the full NMR data of β-carboline-2N-oxide-1-
propionic acid. 
Compound 4 was obtained as yellow powder. Its 
NMR spectral data displayed the signals similar to 
those of 3, except the signals for a methyl ester 
Vietnam Journal of Chemistry Tran Thi Phuong Thao et al. 
© 2020 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 708 
group appeared at δH/δC 3.67 (3H, s)/49.85 
(COOCH3) and at δC 175.00 (COO). This was 
further confirmed by ESI-MS spectrum with a 
molecular ion peak obtained at m/z 254.9 [M+H]
+
Thus, the structure of 4 was determined as infractine 
by comparing its spectral data (table 1) with those 
reported in the literature.
[9] 
This compound has been 
isolated for the first time from E. longifolia. 
Table 1: 
1
H and
 13
C NMR of compounds 1, 3 and 4 
Position 
1 3 4 
δH
a
 (ppm) δC
b
 (ppm) δH
a
 (ppm) δC
b
 (ppm) δH
c
 (ppm) δC
d
 (ppm) 
1 - 147.11 - 144.04 - 142.62 
2 - - - - - - 
3 9.00 (d, J = 5.0) 137.19 8.23 (d, J = 5.5) 137.30 8.22 (d, J = 5.5) 138.25 
4 8.68 (d, J = 5.0) 112.39 7.94 (d, J = 5.5) 112.79 7.95 (d, J = 5.5) 114.41 
5 8.97 (d, J = 8.0) 118.80 8.19 (d, J = 8.0) 119.17 8.17 (dd, 
J = 8.0, 0.5) 
120.79 
6 8.28 (ddd, J = 8.0, 
6.0, 1.0) 
127.45 7.23 (dd, J = 8.0, 1.5) 127.80 7.27 (ddd, 
J = 7.0, 6.0, 1.0) 
129.50 
7 8.00 (ddd, J = 8.0, 
6.0, 1.0) 
121.46 7.53 (ddd, J = 8.0, 
6.8, 1.0) 
121.61 7.56 (ddd, 
J = 7.0, 6.5, 1.0) 
122.62 
8 8.41 (d, J = 8.0) 112.15 7.59 (d, J = 8.0) 111.91 7.62 (dd, 
J = 8.0, 0.5) 
112.89 
9 - 140.48 - 140.35 - 144.94 
10 - 126.91 - 127.01 - 122.65 
11 - 121.12 - 119.01 - 130.32 
12 - 134.46 - 133.99 - 135.91 
1’ 3.36 (t, J = 7.5) 36.65 2.87 (t, J = 7.5) 31.31 2.94 (t, J = 7.5) 33.44 
2’ 4.18 (t, J = 7.5) 31.26 3.35 (t, J = 7.5) 28.04 3.47 (t, J = 7.5) 29.49 
3’ - 177.87 - 174.10 - 175.00 
COOCH3 - - - 3.67 (s, 3H) 49.85 
a
DMSO-d6, 500 MHz, 
b 
DMSO-d6, 125 MHz, 
c
CD3OD, 500 MHz, 
d
CD3OD, 125 MHz. 
Figure 1: The isolated compounds from the roots of Eurycoma longifolia 
Vietnam Journal of Chemistry Phytochemical investigation of E. longifolia 
 © 2020 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 709 
Compound 2 was isolated as yellow powder. 
The ESI-MS of 2 showed a molecular ion peak at 
m/z 280.9 [M+H]
+
. Its 
1
H NMR data showed the 
signals of two methoxy group substituted to 
aromatic ring at δH 4.08 (3H, s, OMe-9) and 4.04 
(3H, s, OMe-10), together with six aromatic protons 
at δH 8.78 (1H, J = 5.0, H-2), 8.22 (1H, s, H-8), 8.00 
(1H, d, J = 10.0, H-4), 7.85 (1H, d, J = 5.0, H-1), 
7.49 (1H, s, H-11) and 6.95 (1H, d, J = 10.0, H-5). 
The 
13
C NMR of 2 indicated the signals of sixteen 
carbons, including 2 methoxy carbons, 6 aromatic 
methine carbons, 7 tertiary carbons and a carbonyl 
amide at δC 159.6. Based on the above spectral data 
and comparison with those in the literature,
[10]
compound 2 was elucidated as 9,10-
dimethoxycanthin-6-one. This compound showed 
the cytotoxic activity against Fibrosarcoma HT-1080 
cancer cell line.
[11] 
Compound 6 was obtained as white powder. Its 
ESI-MS spectrum showed molecular ion peaks at 
m/z 408.9 [M+H]
+
 and 406.8 [M-H]
-
. The NMR 
spectra of 6 dispalyed the signal characteristic for a 
quassinoid structure. The 
1
H NMR of 6 appeared the 
signals of two methyl singlets at δH 1.93 (3H, s, H-
19) and 1.05 (3H, s, H-18), one exomethylene group 
and one olefin proton at δH 5.37 (1H, brs, H-21a), 
5.20 (2H, brs, H-21b and H-3), two methylene 
groups at δH 3.67 (1H, d, J = 8.5, H-20a), 3.53 (1H, 
d, J = 8.5, H-20b) and 2.11 (1H, m, H-6a), 1.97 (1H, 
m, H-6b). Besides, the signals of four oxymethine 
protons were also observed at δH 5.98 (1H, brs, H-7), 
5.64 (1H, s, H-15), 4.59 (1H, brs, H-1) and 4.34 (1H, 
brs, H-12). The other methine protons were 
resonated at δH 2.93 (1H, s, H-9) and 2.50 (1H, m, 
H-5). The 
13
C NMR of 6 showed the signals of 20 
carbons, including four olefin carbons, two carbonyl 
carbons [one δ-lactone carbon at δC 172.33 (C-16) 
and one conjugated ketone carbon at δC 197.10 (C-
2)], four oximethine carbons, oneoxymethylene, one 
hemiacetal carbon at δC 107.80 (C-11), one tertiary 
oxygenated carbon at δC 77.96 (C-14), two methyl 
carbons at δC 9.59 (C-19) and 22.31 (C-18), together 
with other two tertiary carbons, two methine and one 
methylene carbons at δC 51.17-24.61. By comparison 
of MS and NMR data with those reported in the 
literature,
[12]
 compound 6 was determined as 
eurycomanone. Eurycomanone was known as one of 
the main component contributing the bitte taste of E. 
longifolia. It was also reported that eurycomanone 
enhanced the testosterone level in male rats.
[13] 
Compound 7 was isolated as a white powder. 
The NMR spectral data of 7 showed the signals of a 
klaineanone quassinoid compound. An ion 
molecular peak was observed at m/z 433.0 [M+Cl]
-
in its ESI-MS spectrum. The 
13
C NMR of 7 was 
silimar to those of 6, except some following points: 
the conjugated carbonyl carbon was absent, a methyl 
doublet at δH/δC 1.05/18.91 and a methylene group at 
δH 2.11 (1H, m, H-3a), 1.96 (1H, dd, J = 17.5, 10.5, 
H-3b) was assigned to H-21 and H-3, respectively. 
Besides, instead of a hemiacetal in C-ring, the 
signals at δH/δC 1.58 (3H, s)/19.33 and 4.54 (brs, like 
t)/72.51 were assigned for C-20 and C-11, 
respectively. By comparison of NMR spectral with 
those reported in the literature,
[14] 
compound 7 was 
determined as 14,15-β-hydroxyklaineanol. 
Compound 5 was isolated as yellow powder. Its 
ESI-MS showed ion molecular peaks at m/z 577.1 
[M-H2O+H]
+
, 559.2 [M-2H2O+H]
+
; 629.2 [M+Cl]
-
. 
The NMR spectra of 5 showed the signal 
characteristic for a squalene triterpene. The 
13
C 
NMR spectrum of 5 displayed 34 carbon signals, 
including two carbonyl carbons at δC 170.94 (C-31) 
and 170.81 (C-33), four olefin carbons at δC 131.58 
(C-2), 131.57 (C-23), 124.52 (C-3), 124.51 (C-22), 
four oximethines at δC 86.60, 84.38, 78.13, 77.62, 
four tertiary oxygenated carbons at δC 83.82, 83.60, 
72.72, 72.03, ten methylene carbons at δC 45.83-
22.11, together with 10 methyl carbons at δC 25.66-
17.61. However, the intergram in 
1
H NMR showed a 
half of total protons calculating by 
13
C NMR and 
MS spectra. This indicated a symetry in the structure 
feature of compound 5. The 
1
H NMR of compound 5 
displayed the signals of proton olefin at δH 5.10 (t, J 
= 6.0, H-3 and H-22), 4.86 (t, J = 10.0, H-11 and H-
14), two proton oxymethines at δH 3.76 (dd, J = 8.0, 
7.0, H-18) and 3,70 (dd, J = 9.5, 5.5, H-7), two 
methyl acetates (COCH3) at δH 2.07 and 2.06, four 
vinyl methyl at δH 1.68 (s, H-25 and H-30), 1.61 (s, 
H-1 and H-24), together with other methyl singlet at 
δH 1.18 (3H, s, H-29), 1.16 (6H, s, H-26 và H-28), 
1.15 (3H, s, H-27) and methylene protons at δH 2.04-
1.28. The assignment of all protons and carbons was 
deduced by analysis of HSQC and HMBC spectra. 
In HMBC spectrum, the correlation between H-11, 
H-14 (δH 4.86) and H-32, H-34 (δH 2.07 and 2.06)/C-
31 (δC 170.94) and C-33 (δC 170.81) confirmed the 
location of the acetate group at C-11 and C-14. The 
correlation between H-3, H-22 (δH 5.10)/C-1, C-24 
(δC 17.61) and C-25, C-30 (δC 25.66 and 25.64, 
respectively) indicated the position of the double 
bonds. The methyl groups C-27 and C-28 was 
determined to be attached to the tetrahydrofuran ring 
at C-10 and C-15 by the observation of the 
correlation between H-27 (δH 1.15)/C-9 (δC 34.18) 
and H-28 (δH 1.16)/C-16 (δC 34.87). The positions of 
the tertiary oxygenated carbons C-6 and C-19 were 
confirmed by the HMBC correlations between H-7 
(δH 3.76) and H-18 (δH 3.70)/C-26 (δC 24.14) and C-
29 (δC 24.01), respectivey. Based on the above 
Vietnam Journal of Chemistry Tran Thi Phuong Thao et al. 
© 2020 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 710 
analysis and comparison of NMR data of 5 with 
those reported in the literature,
[15]
 compound 5 was 
identified as eurylene. Eurylene composed in its 
backbone 2,5-trans and 2,5-cis-tetrahydrofuran 
units. 
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Corresponding author: Tran Thi Phuong Thao 
Institute of Chemistry, Vietnam Academy of Science and Technology 
18, Hoang Quoc Viet, Cau Giay district, Hanoi 10000, Viet Nam 
E-mail: ntuelam2010@gmail.com 
Tel: +84- 2437562094.