The identification of phenylpropanoids isolated from the root bark of Ailanthus altissima (Mill.) Swingle

Article abstract of DOI:10.1080/14786419.2019.1643861

Chemical investigation of 75% EtOH exact of the root bark of Ailanthus altissima (Mill.) Swingle led to the isolation and identification of two new phenylpropanoids (1–2), along with six known compounds (3–8). Their chemical structures were elucidated by extensive spectroscopic data analyses including NMR experiments and HRESIMS analyses, as well as computer-assisted structure elucidation software (ACD/Spectrus Processor). All compounds were evaluated for cytotoxic activities against Hep 3B and Hep G2 cells. Compound 1 and 7 displayed weak cytotoxic activities against the Hep 3B cell line.

Full text of DOI:10.1080/14786419.2019.1643861

Natural Product Research
Formerly Natural Product Letters
ISSN: 1478-6419 (Print) 1478-6427 (Online) Journal homepage: https://www.tandfonline.com/loi/gnpl20
The identification of phenylpropanoids isolated
from the root bark of Ailanthus altissima (Mill.)
Swingle
Ye-Qing Du, Zhi-Yang Yan, Jing-Jie Chen, Xiao-Bo Wang, Xiao-Xiao Huang &
Shao-Jiang Song
To cite this article: Ye-Qing Du, Zhi-Yang Yan, Jing-Jie Chen, Xiao-Bo Wang, Xiao-
Xiao Huang & Shao-Jiang Song (2019): The identification of phenylpropanoids isolated
from the root bark of Ailanthusꢀaltissima (Mill.) Swingle, Natural Product Research, DOI:
10.1080/14786419.2019.1643861
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NATURAL PRODUCT RESEARCH
https://doi.org/10.1080/14786419.2019.1643861
The identification of phenylpropanoids isolated from the
root bark of Ailanthus altissima (Mill.) Swingle
Ye-Qing Dua, Zhi-Yang Yana, Jing-Jie Chena, Xiao-Bo Wangb,
Xiao-Xiao Huanga,b and Shao-Jiang Songa
aSchool of Traditional Chinese Materia Medica, Key Laboratory of Computational Chemistry-Based
Natural Antitumor drug Research & Development, Liaoning Province, Shenyang Pharmaceutical
b
University, Shenyang, People’s Republic of China; Chinese People0s Liberation Army Logistics
support force No.967 Hospital, Dalian, People’s Republic of China
ABSTRACT
ARTICLE HISTORY
Received 20 May 2019
Accepted 7 July 2019
Chemical investigation of 75% EtOH exact of the root bark of
Ailanthus altissima (Mill.) Swingle led to the isolation and identifi-
cation of two new phenylpropanoids (1–2), along with six known
compounds (3–8). Their chemical structures were elucidated by
extensive spectroscopic data analyses including NMR experiments
and HRESIMS analyses, as well as computer-assisted structure elu-
cidation software (ACD/Spectrus Processor). All compounds were
evaluated for cytotoxic activities against Hep 3B and Hep G2 cells.
Compound 1 and 7 displayed weak cytotoxic activities against
the Hep 3B cell line.
KEYWORDS
Ailanthus altissima;
separation and purification;
structure elucidation;
phenylpropanoid
1. Introduction
Ailanthus altissima (Mill.) Swingle (Simaroubaceae), a deciduous tree, is native to
Mainland China and commonly cultivated in Europe for its ornamental value. (Khan
CONTACT X.-X. Huang
xiaoxiao270@163.com; S.-J. Song
songsj99@163.com
Supplemental data for this article can be accessed at https://doi.org/10.1080/14786419.2019.1643861.
ß 2019 Informa UK Limited, trading as Taylor & Francis Group

2
Y.-Q. DU ET AL.
et al. 2016; Vincenzo et al. 2009; Dao et al. 2012). The root bark of A. altissima has
been used as traditional Chinese medicine for the treatment of bleeding, colds, and
gastric diseases (Wang et al. 2013). Previous pharmacological investigations suggested
that the root bark of A. altissima has a variety of biological activities, including anti-
malarial, antiviral, antifungal, anti-inflammatory and cytotoxic activities (Rahimi et al.
2010; Yan et al. 2018). Furthermore, the root bark of A. altissima is known to produce
different classes of compounds, such as alkaloids (Zhang et al. 2007), quassinoids
(Tamura et al. 2003), lignans (Tan et al. 2012), triterpenoids (Zhou et al. 2011), coumar-
ins (Hong et al. 2013) and other phenolic derivatives (Tan et al. 2008).
The phytochemical investigation on the root bark of A. altissima led to the isolation
of two new phenylpropanoids (1–2), along with six known phenylpropanoids (3–8).
Details of the structural determination of these new compounds as well as the hepa-
toma cell inhibitory activities against Hep 3B and Hep G2 cells of all isolated com-
pounds are described herein.
2. Results and discussion
Compound 1 was obtained as a white amorphous powder. The molecular formula of
1 was established as C14H20O5 based on the HRESIMS molecular-ion peak [M þ Na]þ at
1
m/z 291.1204 (calcd for C14H20O5Na, 291.1203) and 13C NMR data. The H NMR spec-
trum of 1 showed a group of characteristic signals of 1,3,4-substituted benzene ring at
dH 7.03 (1H, d, J ¼ 8.2 Hz, H-5), 6.93 (1H, dd, J ¼ 8.2, 1.6 Hz, H-6) and 6.96 (1H, d,
J ¼ 1.6 Hz, H-2), two methoxys at dH 3.88 (3H, s) and dH 3.39 (3H, s), one trans-double
bond at dH 6.55 (1H, d, J ¼ 15.8 Hz, H-7) and dH 6.19 (1H, dt, J ¼ 15.8, 6.0 Hz, H-8). The
13C NMR spectrum and HSQC spectra revealed 14 carbons (Supplementary information
Table S1) corresponding to an aromatic ring (dC 110.0, 120.3, 120.6, 133.1, 146.9, 151.
5), a double bond (dC 132.0, 125.7), three oxygenated methylenes (dC 73.2, 62.3 ꢀ 2),
one oxygenated methine (dC 84.2), two methoxys (dC 56.1, 58.3).
The attachment of C3 fragment to C-1 was verified by the HMBC correlation from
H-7 (dH 6.55) to C-1 (dC 133.1), C-2 (dC 110.0), C-6 (dC 120.3), and C-9 (dC 73.2). The
HMBC experiment displayed the key correlation from the proton at dH 4.15 (H-20) to
carbon at dC 146.9 (C-4), and from the proton at dH 3.82 (10/30) to carbon at dC 84.2
(C-20), which preliminarily evidenced the linkage of the glycerol and phenyl ring
1
through an O-atom. In H-1H COSY spectrum of 1, a multiplet signal of the methine
hydrogen atom at dH 4.15 (H-20) was observed to correlate with four equivalent hydro-
gen atoms at dH 3.82 (H-10, 30), which further verified the existence of glycerol moiety.
From all the above evidence, the chemical structure of 1 was established as shown
(Figure 1) and identified as 2-[4-(3-methoxy-1-propenyl)-2-methoxy-phenoxy]-propane-
1,3-diol.
Compound 2 was also isolated as a white amorphous powder. Its molecular formula
was designated with a molecular formula of C20H30O12, as deduced by HRESIMS which
exhibited a molecular-ion peak [M þ Na]þ at m/z 485.1601 (calcd for C20H30O12Na,
1
485.1629). The H NMR spectrum of 2 showed five methoxys at dH 3.88 (3H, s), 3.85
(3H, s), 3.85 (3H, s), 3.82 (3H, s) and 3.67 (3H, s), as well as an anomeric carbon signal
of b-configure glucosyl unit at dH 4.69 (1H, d, J ¼ 6.7 Hz, H-10). Analysis of the 13C NMR

NATURAL PRODUCT RESEARCH
3
Figure 1. The structures of compounds 1–8.
and HSQC data revealed the presence of 20 carbons (Supplementary information
Table S2), including one carbonyl moiety, an aromatic ring, five methoxy groups, two
methylenes and a glucopyranosyl unit.
Assignments of all function groups of 2 were achieved by HMBC correlations
(Supplementary information Figure S2, Table S2). The relative position of the glucosyl
group at C-2 was established unambiguously by the HMBC correlation which was
observed between the anomeric proton signal at dH 4.69 (H-10) and dC 144.5 (C-2). The
attachment of one methylpropionate group to C-1 was verified by the HMBC correla-
tions from H-7 (dH 2.99) to C-1 (dC 123.7), C-2 (dC 144.5), C-6 (dC 148.2), C-8 (dC 34.5)
and C-9 (dC 175.2), from the methoxy proton signal at dH 3.67 to carbon at dC 175.2
(C-9). The 6-OCH3 (dH 3.82) at C-6 (dC 148.2), the 4-OCH3 (dH 3.88) at C-4 (dC 146.1)
were established by HMBC analysis. The other two methoxy signals on benzene ring
cannot be unambiguously assigned. Therefore, the obtained spectroscopic data of 2
was analysed using computer-assisted structure elucidation software (ACD/Spectrus
Processor). ACD/Spectrus Processor (Elyashberg and Williams 2015; Naman et al. 2015)
is a kind of software which provides support for all instrument vendor data formats,
and assistance with confirmation that spectral data matches a given chemical struc-
ture/structural fragments. Subsequently, by comparing the experimental with pre-
dicted 13C NMR chemical shift (Supplementary information Figure S1), the aglycone
has been completely assigned (Supplementary information Table S2).
1
For the sugar unit, the H NMR chemical shift dH 4.69 (d, J ¼ 6.7 Hz, H-10) of the
anomeric proton allowed the identification of a b-glucopyranosyl moiety (Yang et al.
2014). Acid hydrolysis of compound 2 gave D-glucose following an LC-NetII/ADC HPLC
analysis according to the retention times (tR) at 10.7 min essentially in agreement
with standard D-glucose. Consequently, the structure of 2 was determined as shown
(Figure
1)
and
identified
as
methyl
3-(2-O-b-D-glucopyranosyl-3,4,5,6-

4
Y.-Q. DU ET AL.
Table 1. Cytotoxic activities of compounds 1–8 (50 lM) in vitro (the inhibition percent, %).
The inhibition percent (%)a Cell line
Compound
Hep 3B
Hep G2
1
2
3
4
5
6
7
8
21.93 0.57
2.02 1.18
4.45 1.77
12.96 0.89
2.05 0.25
12.23 0.36
19.96 0.50
5.96 1.20
65.31 0.93
5.11 0.40
3.17 0.78
11.26 1.32
3.65 1.05
10.79 1.81
11.64 0.52
2.49 1.29
1.54 0.84
83.95 1.84
Sorafenibb
aThe inhibition percent (%) represents means SD of three independent replicates.
bSorafenib was used as positive control.
tetramethoxyphenyl) propanoate, which is an uncommon natural product that is fully
substituted on the benzene ring.
In addition to the above mentioned new compounds, six known compounds were
also isolated and identified as 2-[4-(3-hydroxy-1-propenyl)-2-methoxyphenoxy]-1,3-pro-
panediol (3) (Jiang et al. 2009), 2-[4-(3-hydroxypropyl)-2-methoxyphenoxy]propane-1,
ꢁ
3-diol (4) (Zeng et al. 2014), 7’S -methoxy-7-epi-lariciresinol (5) (Dang et al. 2017),
(-)-secoisolarciresinol (6) (Hiroyuki et al. 1991), (þ)-isolariciresinol (7) (Zhu et al. 2012),
(-)-lyoniresinol (8) (Ouyang et al. 2007; Figure 1), by comparison of their physicochemi-
cal and spectroscopic data with those reported in the literature, respectively.
The isolated compounds were evaluated for their in vitro cytotoxic activities against
the Hep G2 and Hep 3B cell lines by the MTT assay and sorafenib was used as positive
control. As shown in Table 1, Compound 1 and 7 displayed weak cytotoxic activities
against the Hep 3B cell line at the tested concentrations (50 lM).
3. Experimental
3.1. General experimental procedures
The UV spectra were performed on a Shimadzu UV-1700 spectrometer (Shimadzu,
Tokyo, Japan). HRESIMS were obtained on an Agilent G6520 Q-TOF spectrometer
(Agilent, Palo Alto, CA, USA). The NMR spectra were recorded by Bruker AVIII-600 spec-
trometers (Bruker Corporation, Bremen, Germany) with trimethylsilane as an internal
standard and the chemical shifts were indicated as d values (ppm). Preparative HPLC
separation was measured on an instrument Shimadzu LC-10AD pump system and
equipped with Shimadzu RID-20A detector using YMC Pack ODS-A column (250 mm ꢀ
10 mm, 5 lm, Shimadzu, Tokyo, Japan). ACD/Spectrus Processor (ACD/Labs, Toronto,
ON, Canada) was used to assign Compound 2. The configuration of sugar was carried
out by a JAsco LC-NetII/ADC HPLC with JAsco OR-4090 as the detector (JAsco, Japan
spectral co., LTD) and equipped with a Shodex Asahipak NH2P-50 4E column (NO.
N1490155). Silica gel (100–200 and 200–300 mesh, Qingdao Marine Chemical Inc.,
Qingdao, China), HP-20 macroporous resin (75–150 lm, Mitsubishi Chemical Co.,
Japan), ODS silica gel (60–80 lm, Merck, GermanyNacalai Tosoh, Inc., Uetikon,
Switzerland) was used to column chromatography. All solvents were distilled prior to
the separation process.

NATURAL PRODUCT RESEARCH
5
3.2. Plant material
The root bark of A. altissima was collected from Baoding, Hebei province, People’s
Republic of China, on 5 June 2017. Professor Jin-Cai Lu identified this plant material
(School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University). A
voucher specimen (No. 20170605) has been deposited in the herbarium of Shenyang
Pharmaceutical University, Liaoning Province, PR China.
3.3. Extraction and isolation
The air-dried root bark of A. altissima (50 kg) were crushed and extracted in 75% aqueous
ethanol for three times at 70ꢂC (2 hours each time). The concentrated alcohol extract as
suspended in H2O and partitioned successively with EtOAc and n-BuOH. Subsequently, the
n-BuOH extract (360 g) was performed on a silica gel column under reduced pressure and
eluted with a stepwise gradient of CHCl2/CH3OH (from 100:1 to 2:1, v/v) to afford four frac-
tions (Fr. A to Fr. D). Then Fr. A (90g) was chromatographed on HP-20 macroporous resin
using 20%, 40%, 60% and 80% EtOH-H2O to afford Fr. A1 to Fr. A3. The three obtained
portion (Fr. A1, 15g; Fr. A2, 15g; Fr. A3, 40g) were processed on an ODS column with
EtOH-H2O (from 10:90 to 80:20, v/v) to yield four fractions Fr. A1-1 to Fr. A1-4, respectively.
Fr. A1-1 (17g) was chromatographed on a silica gel column eluting with a gradient of
CH2Cl2/MeOH (from 50:1 to 2:1, v/v) to obtain four subfractions (A1-1-1 to A1-1-4).
Subfraction A1-1-1 was further purified by preparative and semi-preparative HPLC using a
YMC Pack ODS-A column with CH3CN/H2O (30:70, v/v, 2.5 mL/min) to afford 2 (17 mg, tR ¼
30.0min), 3 (4.2 mg, tR ¼ 50.0min), 5 (7.6mg, tR ¼ 46.0min). And then subfraction A1-1-4
was separated by preparative and semi-preparative HPLC eluted with CH3CN-H2O (15:85,
v/v, 2.5 mL/min) to afford 1 (8.5 mg, tR ¼ 27.0min), 4 (12.4 mg, tR ¼ 25.0min), 6 (16 mg,
tR ¼ 42min), 7 (7.6 mg, tR ¼ 40 min) and 8 (13 mg, tR ¼ 30min).
3.4. Physical and spectroscopic data of isolated compounds
2-[4-(3-methoxy-1-propenyl)-2-methoxy-phenoxy]-propane-1,3-diol (1): white, amorph-
ous powder. UV (MeOH) kmax (log e) 262 (0.66), 204 (1.00); HRESIMS (m/z): 291.1204
1
[M þ Na]þ (calcd for C14H20O5Na, 291.1203); H NMR (600 MHz, CDCl3) and 13C NMR
(150 MHz, CDCl3) data: see Supplementary information Table S1.
Methyl 3-(2-O-b-D-glucopyranosyl-3,4,5,6-tetramethoxyphenyl) propanoate, (2):
white, amorphous powder. UV (MeOH) kmax (log e): 277 (0.63); HRESIMS (m/z):
1
485.1601 [M þ Na]þ (calcd for C20H30O12Na, 485.1629); H NMR (600 MHz, CDCl3) and
13C NMR (150 MHz, CDCl3) data: see Supplementary information Table S2.
3.5. Acid hydrolysis
Compound 2 (2 mg) was hydrolysed with 1 M HCl (4.0 mL) and heated at 80 ꢂC for 4 h.
The mixture was extracted with EtOAc (3 ꢀ 4.0 mL) after refrigeration. After evaporated
under vacuum, the aqueous layer was concentrated to yield a residue (Bai et al. 2017).
The remaining residue was dissolved in distilled water (1.5 mL) and analysis by a LC-
NetII/ADC HPLC with OR-4090 as the detector and equipped with a Shodex Asahipak

6
Y.-Q. DU ET AL.
NH2P-50 4E column under the following conditions: flow rate at 0.8 mL/min, mobile
phase as MeCN: H2O (75:25) and injection volume was 20 lL. The sugar moiety of
compound 2 was identified to be D-glucose by comparison of the retention times of
those of standard samples [tR (D-glucose) ¼ 10.7 min)].
3.6. Cell culture
Hep 3B and Hep G2 cells were obtained from American Type Culture Collection (ATCC,
Manassas, VA, USA). The cells were cultured in DMEM medium (HyClone, Utah, USA)
supplemented 10% FBS, 10 lg/mL streptomycin and 100 U/mL penicillin (HyClone,
Utah, USA). The cells were cultured at 37 ꢂC with 5% CO2 at a humid atmosphere.
Logarithmically growing cells were used in the experiments.
3.7. In vitro cytotoxicity assay
The cytotoxic activities of all isolates were detected by MTT assay. The cells were
seeded into 96-well cell culture plates (Corning, NY, USA) with 4 ꢀ 103 cells/well over-
night. The cells were treated with indicated concentrations of the tested isolates for
48 h respectively. Then, the wells were added with 20 lL MTT (5 mg/mL) (Sigma
Chemical Co., Ltd., USA). After incubation for 3 h at 37 ꢂC, the absorbance was meas-
ured at 492 nm by microplate reader (Molecular Devices, Thermo, CA, USA). The cell
growth inhibitory ratio was calculated as follows:
Inhibition ratio ¼
A
control– A492;
= A
sampleÞ ð
control– A492;
492;
ꢀ 100
blankÞ
ð
492;
4. Conclusion
In the present study, two new phenylpropanoids (1–2) and six known compounds
(3–8) were isolated from the root bark of A. altissima. The isolated compounds were
characterised by extensive spectroscopic analyses and ACD/Spectrus Processor soft-
ware. In the cytotoxic activities assay, Compound 1 and 7 displayed weak cytotoxic
activities than sorafenib (the positive control) in vitro.
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding
This work was financially supported by the National Nature Science Foundation (81872767) of
the People’s Republic of China and Career Development Support Plan for Young and Middle-
aged Teachers in Shenyang Pharmaceutical University (ZQN2018006).

NATURAL PRODUCT RESEARCH
7
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