A phytochemical study of the ethyl acetate extract (EtOAc) of Styrax annamensis leaves resulted in the isolation and determination of six known compounds, including three nor-Neolignans type 2-phenylbenzofurans egonol (1), egonoic acid (2) and (–)-machice

Cite this paper: Vietnam J. Chem., 2020, 58(5), 597-601 Article 
DOI: 10.1002/vjch.202000018 
597 Wiley Online Library © 2020 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH 
Chemical constituents of Albizia myriophylla wood and the HPLC 
determination of some high yield compounds as markers 
Pham Thi Tam1, Phung Van Trung2, Vo Thi Nga3, Nguyen Thi Anh Tuyet4, 
Nguyen Kim Phi Phung5, Ngo Thi Thuy Duong5, Nguyen Thi Hoai Thu6* 
1Sai Gon University, 273, An Duong Vuong, Dist. 5, Ho Chi Minh City 70000, Viet Nam 
2Center for Research and Technology Transfer, Vietnam Academy of Science and Technology, 
18, Hoang Quoc Viet, Cau Giay, Hanoi 10000, Viet Nam 
3University of Technology and Education Ho Chi Minh City, 1, Vo Van Ngan, Thu Duc, Ho Chi Minh City 
70000, Viet Nam 
4University of Education Ho Chi Minh City, 280, An Duong Vuong, Dist. 5, Ho Chi Minh City 70000, 
Viet Nam 
5University of Science, Vietnam National University - Ho Chi Minh City, 227, Nguyen Van Cu, 
Dist.5, Ho Chi Minh City 70000, Viet Nam 
6University of Medicine and Pharmacy at Ho Chi Minh City, 217, Hong Bang, Dist. 5, Ho Chi Minh City 
70000, Viet Nam 
Submitted February 21, 2020; Accepted March 19, 2020 
Abstract 
Spinasterol (1) and four flavonoids (2-5) were isolated from Albizia myriophylla wood collected at Phu Yen 
province, Vietnam. The chemical structures of these compounds were elucidated by NMR spectroscopy as well as 
compared with data in the literature. The contents of some high yield isolated compounds (2-4) in the ethanol extract of 
A. myriophylla were quantified by high-performance liquid chromatography. These HPLC chromatograms could be 
used to reveal the presence of isolated compounds as markers of the sample. 
Keywords. Albizia myriophylla, flavonoid, content determination, HPLC. 
1. INTRODUCTION 
Albizia myriophylla is widely distributed in Asia 
such as India, Laos, Cambodia, Myanmar, Thailand 
and Vietnam etc.[1] In Vietnamese traditional 
medicine, it was used to cure cough, bronchitis, 
toothache, obesity, dyspepsia, diabetes, cancer etc.[1-
3] There were many researches about chemical 
constituents and bioactivities of Albizia 
myriophylla.[2-5] However, in Vietnam, there has 
been no chemical study on this plant although it is 
now cultivated at Phu Yen province for the internal 
commercial use thanks to its above-mentioned 
medicinal value. 
In this paper, we report the isolation of five 
compounds, spinasterol (1), 7,3',4'-trihydroxy-3-
methoxyflavone (2), fisetin (3), (2S)-7,3',4'-
trihydroxyflavanone (4) and (2S,3S,4S)-7,3,4,3',4'-
pentahydroxyflavane (5). The contents of some high 
yield compounds (2, 3, 4) were determined by HPLC. 
2. MATERIALS AND METHODS 
2.1. General experimental procedures 
The 1H-NMR (500 MHz) and 13C-NMR (125 MHz) 
spectra were recorded on a Bruker AM500 FT-NMR 
spectrometer. LR-MS spectra were recorded by 
UPLC-MS (Ultimate RS 3000 MSQ Pluc. Thermo, 
USA. Optical rotations were measured on a Kruss 
(Germany) polarimeter with the length of the tube of 
2 decimetres. HPLC analyses were carried out on a 
HPLC Hewlett Packard 1050 series system include a 
Quartenary pump, an Autosampler, a Thermostatted 
column and a DAD detector. All moduls and the 
data processing were controlled by Chemstation 
software (Ver. A.10). The column was Phenomenex 
Vietnam Journal of Chemistry Nguyen Thi Hoai Thu et al. 
© 2020 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 598 
LUNA 5u C18 (250×4.6 mm, 5 m). The mobile 
phase was composed of methanol (A) and aqueous 
formic acid 0.1 % (B): from 0-18 min, 35 % A, 65 % 
B; from 19-23 min, 70 % A, 30 % B; from 24-30 
min, 100 % A, 0 % B; at a flow rate 1.0 mL/min. 
Injection volume was of 10 L. All sample and pure 
compounds were filtered by 0.45 m membrane 
before injection. 
2.2. Plant material 
Albizia myriophylla wood sample was collected at 
Hoa Hiep Nam industrial zone, Dong Hoa district, 
Phu Yen province, Vietnam in June, 2018. This was 
the donation of Mr. Hoang Xuan Lam, Middle 
Vietnam Research and Manufacturing Organic 
Medicinal Herb Centre in Phu Yen province. 
2.3. Extraction and isolation 
The dried powder wood (3.1 kg) of A. myriophylla 
was exhaustedly extracted with ethanol by 
maceration at room temperature. After evaporating, 
the ethanolic filtrated solution gave crude extract 
(210 g). This crude was chromatographed on silica 
gel and successively eluted with n-hexane, ethyl 
acetate and methanol to afford three fractions, 
respectively. The ethyl acetate extract was 
chromatographed, eluted with n-hexane:ethyl acetate 
(20:80, 0:100), ethyl acetate:methanol (90:10, 80:20, 
70:30, 0:100) to give 5 sub-fractions, EA1 EA5. 
The sub-fraction EA2 (7.0 g) was applied to a silica 
gel column, and eluted with n-hexane:ethyl acetate 
(96:4) to afford 1 (15 mg). The same procedure for 
the sub-fraction EA3 (5.0 g) was carried out, eluted 
with n-hexane:ethyl acetate (60:40) to obtain 2 (110 
mg), 3 (24 mg), 4 (15 mg) and 5 (8.5 mg). 
Spinasterol (1): white powder. ESI-LRMS: m/z 
473.6 [M+CH3COOH+H]+. 1H-NMR (CDCl3,  
ppm, J in Hertz): 3.59 (1H, m, H3), 5.15 (1H, brs, 
H7), 0.55 (3H, s, H18), 0.80 (3H, s, H19), 1.02 (3H, 
d, 6.5, H21), 5.16 (1H, dd, 14.5, 9.0, H22), 5.03 (1H, 
dd, 15.0, 8.5, H23), 0.85 (3H, d, 6.0, H26), 0.80 (3H, 
d, 6.0, H27), 0.81 (3H, t, 7.0, H29). 13C-NMR 
(CDCl3,  ppm): 37.1 (C1), 31.4 (C2), 71.0 (C3), 
37.9 (C4), 40.2 (C5), 29.5 (C6), 117.4 (C7), 139.5 
(C8), 49.4 (C9), 34.1 (C10), 21.5 (C11), 39.4 (C12), 
43.2 (C13), 55.0 (C14), 22.9 (C15), 28.4 (C16), 55.8 
(C17), 11.9 (C18), 12.9 (C19), 40.7 (C20), 21.3 
(C21), 138.1 (C22), 129.4 (C23), 51.2 (C24), 31.8 
(C25), 21.0 (C26), 18.9 (C27), 25.3 (C28), and 12.1 
(C29). 
7,3',4'-Trihydroxy-3-methoxyflavone (2): 
yellow crystal. ESI-LRMS m/z 301.8 [M+H]+. 1H-
NMR (CDCl3,  ppm, J in He ... LRMS m/z 271.1 [M-H]-. [α]D
25 -22.7 (c 
0.75, EtOAc). 1H-NMR (CDCl3,  ppm, J in Hertz): 
5.23 (1H, dd, 13.0, 2.0, H2), 2.93 (1H, dd, 16.5, 
13.0, H3a), 2.66 (1H, dd, 16.5, 2.5, H3b), 7.70 (1H, 
d, 8.5, H5), 6.44 (1H, dd, 8.5, 1.5, H6), 6.31 (1H, d, 
1.5, H8), 6.87 (1H, d, 2.0, H2 ), 6.77 (1H, d, 8.5, 
H5 ), 6.74 (1H, dd, 8.5, 2.0, H6 ). 13C-NMR (CDCl3) 
data, see table 2. 
Table 1: The contents of some isolated compounds 
in the ethanol extract of A. myriophylla 
Compound 
Rt 
(min) 
Intergration 
C 
(ppm) 
m 
(mg) 
a 
(%) 
Content 
(mg/g) 
2 14.299 299.312 11.62 121.9 15 1.12 
3 14.105 49.500 4.354 121.9 15 0.42 
4 12.083 581.433 12.60 121.9 15 1.22 
C: Concentration of the compound; 
m: Mass of the ethanol extract; 
a: Humidity of the ethanol extract. 
(2S,3S,4S)-7,3,4,3',4'-Pentahydroxyflavane 
(5): brown powder. ESI-LRMS m/z 289.1 [M-H]-. 
[α]D
25 +38.9 (c 4.25, MeOH). 1H-NMR (CD3OD, 500 
MHz,  ppm, J in Hertz): 5.02 (1H, brs, H2), 3.99 
(1H, d, 4.0, H3), 4.95 (1H, d, 4.0, H4), 7.32 (1H, d, 
8.5, H5), 6.45 (1H, dd, 8.5, 2.5, H6), 6.32 (1H, d, 
2.0, H8), 7.05 (1H, d, 1.5, H2 ), 6.80 (1H, d, 8.5, 
H5 ), 6.86 (1H, dd, 8.0, 1.5, H6 ). 13C-NMR 
(CD3OD, 125 MHz) data, see table 2. 
2.4. HPLC determination of major compounds in 
the ethanol extract of A. myriophylla 
Compounds 2, 3, 4 were studied because of their 
good isolated amount and bioactivities.[5] They were 
used as standards with the purity of about 98 %. 
Vietnam Journal of Chemistry Chemical constituents of Albizia myriophylla 
© 2020 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 599 
Establish of standard curve of pure compounds 
To establish of standard curve of pure compounds, 
10 mg of each compound was weighted and 
dissolved perfectly in 10 mL MeOH as stock 
solution. A certain amount of this solution of each 
compound was then taken and diluted to 10 mL in a 
volumetric flask to get standard solutions. The 
standard curve for each compound was performed as 
shown in figures 1 and 2. 
Figure 1: Standard curves of (2), (3), (4) 
Preparation of sample 
100 mg of the ethanol extract was weighted and 
dissolved perfectly in 10 mL MeOH then filtered by 
using a 0.45-m membrane before injection. 
Content calculation of 2-4 in the ethanol extract 
The content of each compound in the ethanol 
extract was determined by the following formula and 
the result was presented in table 1. 
C: Concentration of compound (ppm) calculated 
from standard curve equation; V: Volumetric 
volume (mL); m: Mass of ethanol extract (g); 
a: Humidity of ethanol extract (%). 
Figure 2: HPLC chromatograms of 2, 3, 4 
(the lower lines) and ethanol extract (the upper lines) 
at  = 350 nm, 350 nm, 280 nm, respectively 
3. RESULTS AND DISCUSSION 
Compound 1 was isolated as a white powder. The 
1H-NMR spectrum showed signals of three olefin 
protons at H 5.15 (H7), 5.16 (H22), 5.03 (H23), and 
one oxymethine group at H 3.59 (H3). In the higher 
magnetic field, there were six signals of methyl 
groups including two singlets (H 0.55, H18), 0.80 
(H19)], three doublets (H 1.02, H21), 0.85 (H26), 
0.80 (H27)], and one triplet (H 0.81, H29)]. The 
13C-NMR spectrum indicated the presence of 29 
carbons with two C=C bonds, one oxymethine group 
and six methyl groups. 1 was elucidated as 
spinasterol by the good compatibility of its MS and 
NMR data with those in the literature.[6] 
Compound 2 was isolated as a yellow crystal. 
The 1H-NMR spectrum displayed three signals of 
min2.5 5 7.5 10 12.5 15 17.5 20 22.5
mAU
0
20
40
60
80
100
 DAD1 E, Sig=350,16 Ref=550,100 (KQ_HPLC1\CT_AM414.D)
 1
4.
25
9
 DAD1 E, Sig=350,16 Ref=550,100 (KQ_HPLC1\CT_EA-40.D)
 5
.0
51
 5
.7
36
 6
.1
84
 6
.6
19
 6
.9
46 8
.8
59
 9
.9
12
 1
0.
38
9
 1
0.
84
2
 1
1.
28
3
 1
2.
02
6
 1
3.
37
2
 1
4.
29
9
 1
4.
65
5
 1
5.
02
1
 1
5.
50
8
 1
6.
60
2
 1
7.
88
1
 1
8.
18
5
 1
8.
47
2
 1
8.
65
9
 1
8.
92
6
 1
9.
10
0
 2
0.
68
7
Ethanol extract
Compound 2
min2.5 5 7.5 10 12.5 15 17.5 20 22.5
mAU
0
20
40
60
80
 DAD1 E, Sig=350,16 Ref=550,100 (D:\KETQUA~1\CHI_TAM\CT_EA000.D)
 1
.8
47
 2
.1
06
 2
.5
65
 1
0.
79
3
 1
3.
77
8
 1
4.
10
5
 1
4.
51
6
 2
3.
02
6
 DAD1 E, Sig=350,16 Ref=550,100 (D:\KETQUA~1\CHI_TAM\CT_AM802.D)
 1
4.
14
1
Ethanol extract
Compound 3
min2 4 6 8 10 12 14 16 18
mAU
-20
0
20
40
60
80
100
120
 DAD1 D, Sig=280,16 Ref=550,100 (D:\KETQUA~1\CHI_TAM\CT_EA000.D)
 4
.5
02
 5
.7
51
 6
.8
54 7
.6
29
 8
.4
05
 9
.6
52
 1
1.
47
9
 1
2.
08
3
 1
3.
78
0
 1
4.
51
8
 DAD1 D, Sig=280,16 Ref=550,100 (D:\KETQUA~1\CHI_TAM\CT_AM500.D)
 1
2.
07
0
 DAD1 D, Sig=280,16 Ref=550,100 (D:\KETQUA~1\CHI_TAM\CT_AM500.D)
 1
2.
07
0
Compound 4
Ethanol extract
Vietnam Journal of Chemistry Nguyen Thi Hoai Thu et al. 
© 2020 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 600 
aromatic protons at H 7.95 (1H, d, 8.5 Hz, H5), 6.81 
(1H, dd, 8.5, 2.0 Hz, H6), 6.80 (1H, d, 2.0 Hz, H8), 
confirming the presence of a 1,2,4-trisubstituted A 
benzene ring system of flavonoids. The 1 ,3 ,4 -
trisubstituted B benzene ring was determined by the 
signals of three aromatic protons at H 7.60 (1H, d, 
1.5 Hz, H2 ), 6.86 (1H, d, 8.5 Hz, H5 ), 7.49 (1H, 
dd, 8.5, 1.5 Hz, H6 ). Additionally, the 1H-NMR 
spectrum showed one methoxy group at H 3.70. The 
13C-NMR spectrum corresponded to 15 carbons, 
including one carbonyl carbon at C 175.3 (C4), six 
oxygenated aromatic carbons and eight aromatic 
carbons (table 2). The HMBC correlation between 
protons of -OCH3 with C3 confirmed this methoxy 
group attached to C3. Based on all the 
aforementioned analysis and the comparison of MS 
and NMR data (table 2) with those reported in the 
literature,[7] 2 was determined as 7,3',4'-trihydroxy-
3-methoxyflavone. 
Table 2: 13C-NMR data of isolated compounds 
No 
C (ppm) 
2a 3b 4a 5b 
2 156.1 148.5 80.4 78.5 
3 140.1 138.4 44.6 69.4 
4 175.3 174.3 192.8 67.2 
5 126.9 127.3 129.8 128.3 
6 115.1 115.8 111.6 108.3 
7 162.5 164.1 165.8 157.4 
8 102.3 102.8 103.7 101.9 
9 157.2 158.3 164.6 155.1 
10 116.9 115.3 114.7 115.0 
1 122.5 124.2 131.3 130.4 
2 115.3 116.1 114.1 114.0 
3 144.5 147.4 145.9 144.6 
4 147.6 146.1 145.5 144.6 
5 114.9 115.8 115.9 114.6 
6 121.4 121.7 119.2 118.0 
3-OCH3 59.5 - - - 
a) In CDCl3; b) In CD3OD. 
Compound 3 was isolated as a yellow crystal. 
The NMR data of 3 were similar to those of 2, 
except that the methoxy group at C3 was replaced by 
a hydroxyl group. Based on the MS and NMR data 
(table 2) compared to the ones in published data,[8] 3 
was identified as fisetin. 
Compound 4 was isolated as a yellow powder. 
The NMR data demonstrated that 4 was a flavanone 
with the lack of double bond at C2. The comparison 
of the measured specific optical rotation value of 4 
{[α]D
25 –22.7 (c 0.75, EtOAc)} with the ones of (2S)-
7,3',4'-trihydroxyflavanone isomer {[α]D
22 -36.1 (c 
0.8, MeOH) or [α]D
30 -18.7 (c 0.5, MeOH)},[9] as 
well as the good compatibility of its MS and NMR 
data (table 2) with those published in the 
literature,[9,10] 4 was thus (2S)-7,3',4'-
trihydroxyflavanone. 
Figure 3: Structures of isolated compounds from 
Albizia myriophylla wood 
Compound 5 was obtained as a brown powder. 
The NMR data suggested that 5 was a flavanane 
derived from 3 with the disappearance of the double 
bond at C2 and the carbonyl group at C4 and the 
appearance of two hydroxyl groups at C3 and C4. 
According to Drewes et al.,[11] the coupling 
constants J2,3 and J3,4 (in Hertz) of flavan-3,4-diol 
derivatives were around 1.0 and 4.4 in (+)-2,3-cis-
3,4-cis isomer; 1.0 and 2.7 in (+)-2,3-cis-3,4-trans 
isomer; 10.0 and 3.4 in (+)-2,3-trans-3,4-cis isomer; 
and 9.0 and 7.1 in (+)-2,3-trans-3,4-trans isomer, 
respectively. Compound 5 possessed a set of proton 
signals including 5.02 (brs, H-2), 3.99 (dd, 1.0, 4.0 
Hz, H-3) and 4.95 (d, 4.0 Hz) corresponding to the 
coupling constants of (+)-2,3-cis-3,4-cis isomer. MS 
and NMR data (table 2) of 5 were compatible with 
those of published ones.[2,12] The dextrorotatory 
value of 5 {[α]D
25 +38.9 (c 4.25, MeOH)} matched 
with the one of [α]D
20 +48.5 (c 0.8, acetone-H2O) 
reported for (2S,3S,4S)-7,3 ,4 -trihydroxy-2,3-cis-
flavan-3,4-cis-diol.[13] Therefore 5 was assigned as 
(2S,3S,4S)-7,3,4,3',4'-pentahydroxyflavane. 
The contents of some isolated compounds in the 
ethanol extract of A. myriophylla determined by 
HPLC were displayed in table 1 and figures 1-2. 
From the results, these flavonoids 2-4 were found as 
major compounds in the ethanol extract of A. 
myriophylla wood. These HPLC chromatograms 
could be used to reveal the presence of isolated 
compounds as markers of the sample. Fisetin (3) had 
Vietnam Journal of Chemistry Chemical constituents of Albizia myriophylla 
© 2020 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 601 
a small content in the ethanol extract, however it 
possessed potential interest in the prevention or 
treatment of cancer in vivo, antioxidant and anti-
inflammatory[5] The bioactivities of the two rest 
flavonoids (2, 4) have not much been studied. 
Compound 2 showed no active in assays of the 
inhibition of xanthine oxidase[14] as well as 
antimalarial activity against Plasmodium 
falciparum.[15] Compound 4 was tested for free 
radical scavenging activity and its percentage of 
reduced DPPH was 14.5 % at a dose of 4 10-8 
mol.[15] Therefore, it needs necessary research for the 
biological properties of these compounds in order to 
support the traditional use of A. myriophylla wood. 
4. CONCLUSION 
From the Albizia myriophylla wood, collected at Phu 
Yen province, spinasterol (1) and four flavonoids (2-
5) were isolated and elucidated the structures. This is 
the first time these compounds are known in A. 
myriophylla. The contents of some high yield 
isolated compounds (2-4) in the ethanol extract were 
determined by HPLC and these chromatograms 
could be used as markers to verify the presence of 
major flavonoids of the sample. 
Acknowledgements. We are grateful to Mr. Hoang 
Xuan Lam (Co-Founder of HerbEco Company) for 
Albizia myriophylla sample and M.Sc. Bui Ngoc Duy 
for the good image of the plant. 
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Corresponding author: Nguyen Thi Hoai Thu 
 University of Medicine and Pharmacy at Ho Chi Minh City 
 217, Hong Bang Street, District 5, Ho Chi Minh City 70000, Viet Nam 
 E-mail: nguyenthihoaithu@ump.edu.vn; Tel.: +84- 904203342.