Oleanane-type triterpene saponins from Aralia armata leaves and their cytotoxic activity

Article abstract of DOI:10.1080/14786419.2020.1768090

Two new, aramatosides A and B (1 and 2), together with seven known oleanane-type triterpene saponins (3–9) were isolated from the leaves of Aralia armata. Their structures were determined by combination of HR-ESI-MS, 1 D and 2 D NMR spectral data as well as comparison with the previous literature. Compounds 6–9 exhibited cytotoxic effects towards three human cancer cell lines (HT29, A2058, and A549) with IC₅₀ values ranging from 2.01 ± 0.17 to 18.8 ± 1.17 μM. Especially, compound 7 (narcissiflorin) showed significant cytotoxic activity against HT29 and A549 cell lines with IC₅₀ values of 2.02 ± 1.65 and 2.01 ± 0.17 μM, respectively, which are smaller than those of positive control irinotecan hydrochloride (IC₅₀ values of 10.3 ± 1.32 and 9.89 ± 0.19 μM).

Full text of DOI:10.1080/14786419.2020.1768090

Natural Product Research
Formerly Natural Product Letters
ISSN: 1478-6419 (Print) 1478-6427 (Online) Journal homepage: https://www.tandfonline.com/loi/gnpl20
Oleanane-type triterpene saponins from Aralia
armata leaves and their cytotoxic activity
Pham Hai Yen, Nguyen Thị Hong Chuong, Giang Thi Kim Lien, Nguyen Thi
Cuc, Nguyen Xuan Nhiem, Nguyen Thi Viet Thanh, Bui Huu Tai, Yohan Seo,
Wan Namkung, SeonJu Park, Seung Hyun Kim, Chau Van Minh & Phan Van
Kiem
To cite this article: Pham Hai Yen, Nguyen Thị Hong Chuong, Giang Thi Kim Lien, Nguyen Thi
Cuc, Nguyen Xuan Nhiem, Nguyen Thi Viet Thanh, Bui Huu Tai, Yohan Seo, Wan Namkung,
SeonJu Park, Seung Hyun Kim, Chau Van Minh & Phan Van Kiem (2020): Oleanane-type
triterpene saponins from Araliaꢀarmata leaves and their cytotoxic activity, Natural Product
Research, DOI: 10.1080/14786419.2020.1768090
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NATURAL PRODUCT RESEARCH
https://doi.org/10.1080/14786419.2020.1768090
Oleanane-type triterpene saponins from Aralia armata
leaves and their cytotoxic activity
Pham Hai Yena,b, Nguyen Thị Hong Chuongc, Giang Thi Kim Liend, Nguyen Thi
Cuca, Nguyen Xuan Nhiema,b, Nguyen Thi Viet Thanhe, Bui Huu Taia,b, Yohan
Seof, Wan Namkungf, SeonJu Parkg , Seung Hyun Kimf , Chau Van Minha
and Phan Van Kiema,b
aInstitute of Marine Biochemistry, Vietnam Academy of Science and Technology (VAST), Hanoi,
b
Vietnam; Graduate University of Science and Technology, Vietnam Academy of Science and
c
Technology (VAST), Hanoi, Vietnam; University of Education, The University of Danang, Danang,
d
e
Vietnam; The University of Danang, Danang, Vietnam; School of Chemical Engineering, Hanoi
f
University of Science and Technology, Hanoi, Vietnam; Yonsei Institute of Pharmaceutical Sciences,
College of Pharmacy, Yonsei University, Incheon, Korea; Chuncheon Center, Korea Basic Science
g
Institute (KBSI), Chuncheon, Republic of Korea
ABSTRACT
ARTICLE HISTORY
Received 21 March 2020
Accepted 29 April 2020
Two new, aramatosides A and B (1 and 2), together with seven
known oleanane-type triterpene saponins (3–9) were isolated from
the leaves of Aralia armata. Their structures were determined by
combination of HR-ESI-MS, 1 D and 2 D NMR spectral data as well
as comparison with the previous literature. Compounds 6–9 exhib-
ited cytotoxic effects towards three human cancer cell lines (HT29,
A2058, and A549) with IC50 values ranging from 2.01 0.17 to
18.8 1.17mM. Especially, compound 7 (narcissiflorin) showed sig-
nificant cytotoxic activity against HT29 and A549 cell lines with
IC50 values of 2.02 1.65 and 2.01 0.17mM, respectively, which
are smaller than those of positive control irinotecan hydrochloride
(IC50 values of 10.3 1.32 and 9.89 0.19mM).
KEYWORDS
Aralia armata; aramatoside
A; aramatoside B; oleanane
saponin; cytotoxicity
CONTACT Phan Van Kiem
phankiem@yahoo.com
Supplemental data for this article can be accessed online at https://doi.org/10.1080/14786419.2020.1768090.
ß 2020 Informa UK Limited, trading as Taylor & Francis Group

2
P. H. YEN ET AL.
1. Introduction
Genus Aralia comprises over 70 species that distributes mainly in the Asia, North and
South America (Jason and Ella 2014). The dried leaves, roots and stem barks of several
Aralia species have been used in the traditional medicines where they are indigenous,
such as A. armata (Hu et al. 1995; Miao et al. 2016), A. elata (Song et al. 2001; Zhang
et al. 2018), A. chinensis (Zhang et al. 2019), and A. echinocaulis (Li et al. 2017). Several
Aralia plants have been chemically investigated and obtained substances belonging
triterpenoid saponins, diterpenoids, phenolics, and acetylenic lipids. Especially, olea-
nane-type triterpene saponins were reviewed to be major chemical constituents of
Aralia genus and expected responsibility for anti-inflammation, anti-diabetes, cardio-
vascular properties, and anti-proliferative effects (Jason and Ella 2014). The A. armata
is common herbal in China and Viet Nam that has been used with tonic, anti-
inflammation, and anti-bacterial properties. Up to date, a few chemical studies have
been done and led to identification of triterpenes, triterpene saponins from the stem
bark and root bark of A. armata, showing herbicidal and cytotoxic activities (Hu et al.
1995; Miao et al. 2016). Continuing research to find triterpene saponins from medicinal
plant A. armata (Trang et al. 2015), herein, we report the identification of two new (1
and 2) and seven known oleanane-type triterpene saponins (3–7) from the leaves of
A. armata. Cytotoxic activity of the isolated compounds on HT29 (human colorectal
adenocarcinoma), A2058 (human caucasian metastatic melanoma), and A549 (human
lung adenocarcinoma) cell lines were also evaluated.
2. Results and discussion
Compound 1 was isolated in form of white amorphous powder. The HR-ESI-MS (nega-
tive mode, Figure S3) of 1 showing quasi-molecular ion peaks at m/z 941.4767 [M-H]-
and m/z 977.4533 [M þ Cl]- indicated its molecular formula to be C47H74O19 (calcd. for
1
C47H73O19, 941.4746; and calcd. for C47H74O1935Cl, 977.4513). The H NMR spectrum of
compound 1 (Figure S4) showed 7 singlet methyl signals (dH 1.19, 1.06, 1.01, 0.96,
0.96, 0.86, and 0.85), an olefinic proton [dH 5.26 (1H, br s)], and three anomeric protons
[dH 5.20 (1H, br s), 4.88 (1H, d, J ¼ 8.0 Hz), 4.37 (1H, d, J ¼ 8.0 Hz)]. The 13C NMR of com-
pound 1 contained signals corresponding to 47 carbon atoms which were categorized
by DEPT spectra into 9 non-protonated carbons, 20 methines, 11 methylenes, and 7
methyl groups (Figure S5 and S6, Table S1). In which, two deshielded signals (dC 181.0
and 176.5) corresponded to two carbonyl groups. Two olefinic carbon signals [dC
144.6 (C) and 123.7 (CH)] suggested the presence of a C ¼ C double bond. Three
anomeric carbon signals [dC 108.3, 106.3, and 104.3] indicated the presence of three
monosaccharide units. Those characteristic NMR data suggested compound 1 belong
to oleanane-type triterpene saponin that commonly reported in the Aralia genus
(Jason and Ella 2014). Moreover, aglycon moiety of 1 were deduced to be 3b,21a-dihy-
droxyolean-12-ene-28-oic acid by analysis of HSQC, HMBC, and COSY spectra (Figure
S1, S7-S9). Particularly, the chemical shift values of H-3 (dH 3.14)/C-3 (dC 90.9), HMBC
correlations between H3-23 (dH 1.06)/H3-24 (dH 0.85) and C-3/C-4 (dC 40.2)/C-5 (dC 57.0)
indicated an oxygenated group at C-3. HMBC correlations between H3-25 (0.96)/H3-26
1
(dH 0.86) and C-9 (dC 48.8), H-1H COSY cross peaks of H-9 (dH 1.58)/H2-11 (dH 1.88 and

NATURAL PRODUCT RESEARCH
3
1.91)/H-12 (dH 5.26), and chemical shift value of C-12 (dC 123.7) demonstrated a C ¼ C
double bond at C-12/C-13. The location of this double bond was further supported by
HMBC correlation between H3-27 (dH 1.19) and C-13 (dC 144.6). COSY cross peaks of H-
18 (dH 2.84)/H2-19 (dH 1.11 and 1.74), HMBC correlations between H3-29 (dH 0.96)/H3-
30 (dH 1.01) and C-19 (dC 46.9)/C-20 (dC 32.1)/C-21 (dC 42.9), COSY cross peaks of H2-21
(dH 1.41 and 1.39)/H-22 (dH 3.86), and chemical shift value of C-22 (dC 72.5) indicated
an additional oxygenated group at C-22. HMBC correlation between H-22 and carbonyl
carbon C-28 (dC 181.0) revealed a carboxylic group C-28 and then established structure
of 3,21-dihydroxyolean-12-ene-28-oic acid moiety. Based on the biosynthesis of olea-
nane skeleton, two methyl groups (C-25 and C-26) and a proton H-18 located at
b-orientations meanwhile two protons (H-5 and H-9) and a methyl group (C-27) were
at a-orientations. Therefore, NOESY correlation between H-18 (dH 2.84) and H-22 (dH
3.86) indicated a-orientation of hydroxy group at C-22. NOESY correlation between H-
5 (dH 0.79) and H-3 (dH 3.14) confirmed b-orientation of oxygenated group at C-3
(Figure S1 and S10). Signals of 17 carbon atoms belonging sugar moiety indicated
that it contained two hexose and one pentose units. Furthermore, observation of a
carbonyl carbon (dC 176.5) suggested the presence of a glucuronic acid monosacchar-
ide. Anomeric carbon and proton signals (dH 5.20/dC 108.3) were characterized for an
arabinofuranosyl group (Rengifo et al. 2017). Another monosaccharide group was
expected to be glucopyranosyl group by six carbinol signals (dC 104.3, 78.2, 77.9, 75.6,
71.1, 62.2). Additionally, HMBC correlation between Glu H-10 (dH 4.37) and aglycon C-3
(dC 90.9) indicated that O-glucuronopyranosyl group link to the aglycon at C-3. The
NMR spectral assignment of glucuronopyranosyl group was further clarified by COSY
cross peaks of Glu H-10 (dH 4.37)/Glu H-20 (dH 3.56)/Glu H-30 (dH 3.77)/Glu H-40 (dH
3.86)/Glu H-50 (dH 3.69). HMBC correlation between Glc H-100 (dH 4.88) and Glu C-30 (dC
82.1), Ara H-1000 (dH 5.20) and Glu C-40 (dC 75.4) indicated O-glucopyranosyl group at C-
30 and O-arabinofuranosyl group at C-40 of glucuronopyranosyl moiety, respectively.
Multiplicity of anomeric protons Glu H-10 (d, J ¼ 8.0 Hz), Glc H-100 (d, J ¼ 8.0 Hz), and
Ara H-1000 (br s) suggested b-linkage of glucuronopyranosyl, b-linkage of glucopyrano-
syl, and a-linkage of arabinofuranosyl groups, respectively. Monosaccharides in
the sugar residue were further confirmed to be D-glucuronic acid, D-glucose, and L-
arabinose by hydrolysis, convert to thiazolidine derivatives, HPLC analysis and compari-
son retention time with that of standard monosaccharide derivatives prepared in the
same procedure (Tanaka et al. 2007). Consequently, compound 1 was determined to
be 3b,21a-dihydroxyolean-12-ene-28-oic acid 3-O-[40-O-a-L-arabinofuranosyl-(30-O-b-D-
glucopyranosyl)]-b-D-glucuronopyranoside, a new compound named as aramatoside A.
Compound 2 was isolated as a white amorphous powder. A pair of quasi-molecular
ion peaks at m/z 941.4768 [M-H]- (calcd. for C47H73O19, 941.4746) and m/z 977.4536
[M þ Cl]- (calcd. for C47H74O1935Cl, 977.4513) in the HR-ESI-MS of 2 (Figure S11) indi-
cated that compounds 2 and 1 shared the same molecular formula of C47H74O19. The
1H-NMR spectrum of 2 (Figure S12) observed 6 singlet methyl groups [dH 0.71, 0.88,
0.90, 0.97, 0.99, 1.17 (each 3H, s)], an olefinic proton [dH 5.23 (1H, br s)], and three
anomeric protons [dH 4.47 (1H, d, J ¼ 8.0 Hz), 4.84 (1H, d, J ¼ 8.0 Hz), 5.20 (1H, br s)].
The 13C-NMR and DEPT spectra of 2 showed signals corresponding to 47 carbon atoms
including 9 non-protonated carbons, 19 methines, 13 methylenes, and 6 methyl groups

4
P. H. YEN ET AL.
Figure 1. Chemical structures of oleanane-type triterpene glycosides isolated from A. armata.
(Figure S13-S17). Seventeen carbons in sugar moiety of 2 were in close similar chemical
shift values with those of 1 which indicated compounds 1 and 2 containing the same tri-
saccharide moiety 40-O-a-L-arabinofuranosyl-(30-O-b-D-glucopyranosyl)]-b-D-glucuronopyra-
noside (Table S2). HMBC correlation between Glu H-10 (dH 4.47) and C-3 (dC 83.1)
confirmed O-glycosidic linkage at C-3 of the aglycone (Figure S2). Moreover, HMBC corre-
lations between H3-24 (dH 0.71) and C-3/C-4 (dC 43.9)/C-5 (dC 48.2)/C-23 (dC 65.0) indicated
the presence of hydroxy group at C-23. The COSY cross peaks of H-9 (dH 1.74)/H-11 (dH
1.92)/H-12 (dH 5.23) and HMBC correlation of H3-27 (dH 1.17)/C-13 (dC 146.6) supported for
the position of C ¼ C double bond at C-12/C-13. Therefore, the aglycone of 2 was estab-
lished to be 3b,23-dihydroxyolean-12-ene-28-oic acid. Due to containing hydroxy group
at C-23, the stereochemistry at C-4 of 2 was then demonstrated by NOESY analysis (Fig
S2 and S18). NOESY correlations between H3-24 (dH 0.71) and H3-25 (dH 0.99), H-5 (dH
1.25) and H2-23 (dH 3.62 and 3.28)/H-3 (dH 3.64) indicated that methyl groups C-24 and
C-25 located at b-orientations meanwhile protons H-3, H-5 and hydroxymethylene
group (C-23) located at a-orientations. Consequently, compound 2 was determined to
be 3b,23-dihydroxyolean-12-ene-28-oic acid 3-O-[40-O-a-L-arabinofuranosyl-(30-O-b-D-glu-
copyranosyl)]-b-D-glucuronopyranoside, a new compound named as aramatoside B.
Other compounds were determined to be 3-O-a-L-arabinofuranosyl-(1!4)-b-D-glucuro-
nopyranosylhederagenin 28-O-b-D-glucopyranosyl ester (3) (Rengifo et al. 2017), 3-O-[a-L-
arabinopyranosyl-(1!3)-b-D-glucuronopyranosylhederagenin
28-O-b-D-glucopyranosyl
ester (4) (Rastrelli et al. 1996), 3-O-b-D-glucuronopyranosylhederagenin 28-O-b-D-glucopyr-
anosyl ester (5) (Dovgii et al. 2006), Stipuleanoside R1 (6) (Hu et al. 1995), Narcissiflorin (7)
(Masood et al. 1981; Fujioka et al. 1989), Chikusetsusaponin IVa (8) (Liang et al. 2010), and
oleanolic acid 28-O-b-D-glucopyranosyl ester (9) (Young et al. 1997) by their good consist-
ence with those reported in the literature (Figure 1).
The isolated compounds were then evaluated their cytotoxic activity. Compounds
1-9 were first screened their effects on the viability of HT29 cells. At a concentration
of 30 mM, compounds 1-5 showed inactivity (cell viability over than 90%) meanwhile
compounds 6-9 exhibited potential cytotoxic activity with cell viability ranging from

NATURAL PRODUCT RESEARCH
5
4.21 0.06% to 7.56 0.11% versus vehicle experiments (Table S3). Based on the
screening results, compounds 6-9 were subjected to further study to find IC50 values
and investigate their cytotoxicity against two additional human cancer cell lines
including A2058 and A549 cell lines. As the results (Table S4), compounds 6–9 dis-
played cytotoxic activity toward HT29, A2058, and A549 cell lines with IC50 values
from 2.01 0.17 to 18.8 1.17 mM. Compound 7 exhibited the best cytotoxic effect
toward HT29, A2058, and A549 cell lines with the IC50 values of 2.02 1.65, 4.26 0.50,
2.01 0.17 mM, respectively. Additionally, in the HT29 and A549 cell lines experiments,
the IC50 values of compounds 7 (2.02 1.65 and 2.01 0.17) and 9 (6.51 1.64 and
6.51 1.6) were found smaller than those of known anti-cancer agent, irinotecan
hydrochloride (10.3 1.32 and 9.89 0.19). For the structure and cytotoxicity relation-
ship of compounds 1-9, our results revealed that an additional of hydroxy group even
at C-23 or C-22 of 3b-hydroxyolean-12-ene-28-oic moiety could be reduced their cyto-
toxic activity on HT29, A2058, and A549 cell lines.
3. Experimental
3.1. General
Optical rotation was measured on a Jasco P2000 polarimeter. NMR spectra were
recorded on a Bruker 500 MHz spectrometer. HR-ESI-MS was carried out on an Agilent
6530 Accurate Mass Q-TOF LC/MS. The QTOF instrument was set at 2 GHz extended
dynamic range resolution mode, negative ESI capillary voltage of 3500 V, fragmentor
voltage of 175 V, MS scan ranging at m/z 100-1700, and MS acquisition rate of 1.0
spectra per second. Column chromatography was performed using silica gel, reverse
phase C-18, and diaion HP-20 resins as stationary phase. Thin layer chromatography
was carried out using pre-coated silica gel 60 F254 and RP-18 F254S plates. The spots
were visualized by spraying with solution of H2SO4 5% in ethanol followed by heating
with a heat gun.
3.2. Plant material
The plant samples, Aralia armata leaves, were collected at Vinh Phuc province, Viet
Nam in December 2017. Its scientific name was identified by botanist Nguyen The
Cuong at the Institute of Ecology and Biological Resources, VAST. Voucher specimen
(coded: NCCT-P71) was deposited at the Institute of Marine Biochemistry, VAST.
3.3. Extraction and isolation
Dried Aralia armata leaves (6 kg) were pulverized and then ultrasonically extracted
with MeOH for three times (each 15 L of MeOH in 30 minutes). After filtration, the solv-
ent was removed in vacuo to give 240 g of a dark methanolic residue. This crude
extract was suspended in water and successively partitioned with dichloromethane
and ethyl acetate to give organic soluble fractions and water layer. The water layer
was poured on a diaion (HP-20) column and washed with water to remove salts and
oligosaccharides. Saponin compounds were stepwise eluted by methanol/water (25%,

6
P. H. YEN ET AL.
50%, 75%, and 100% volume of methanol) to give four fractions AAW1-AAW4.
Fraction AAW2 (15.5 g) was separated by silica gel column chromatography, eluting
with dichloromethane/methanol (1/0-0/1, v/v) to give five fractions AAW2A- AAW2E.
Fraction AAW2B was further fractionated on a reverse phase C18 column, eluting with
methanol/water (2/3, v/v) to give three fractions AAW2B1- AAW2B3. Fractions AAW2B1
and AAW2B3 were purified on silica gel column, eluting with dichloromethane/acet-
one/water (1/4/0.6, v/v/v) to yield compounds 3 (20 mg) and 4 (15 mg), respectively.
Fraction AAW2B2 was purified on a reverse phase C18 column, eluting with acetone/
water (2/5, v/v) to give compound 5 (11 mg). Fraction AAW4 (40 g) was also separated
by silica gel column chromatography, eluting with dichloromethane/methanol (1/0-0/
1, v/v) to give five fractions AAW4A- AAW4E. Fraction AAW4A was first chromato-
graphed on a silica gel column eluting with dichloromethane/acetone/water (1/3/0.4,
v/v/v) and then purified by reverse phase C18 column eluting with acetone/water (2/5,
v/v) to yield compound 9 (9 mg). Fraction AAW4B was separated on a reverse phase
C18 column, eluting with acetone/water (2/5, v/v) to obtain three fractions AAW4B1-
AAW4B3. Fraction AAW4B1 and AAW4B2 were purified on a silica gel column, eluting
with dichloromethane/acetone/water (1/3/0.4, v/v/v) to yield compounds 7 (8 mg) and
2 (8 mg), respectively. Fractions AAW4B3 was purified on a reverse phase column, elut-
ing with methanol/water (1/1.2, v/v) to yield compound 6 (10 mg). Fraction AAW4C
was purified on a reverse phase C18 column, eluting with methanol/water (1/1, v/v) to
give compound 8 (12 mg). Compound 1 (20 mg) was isolated from fraction AAW4D by
a reverse phase C18 column using acetone/water (2/5, v/v) as an eluent.
3.3.1. Aramatoside A (1)
25
White amorphous powder, ½aꢀD : ꢁ73.6ꢂ (c 0.1, MeOH); HR-ESI-MS m/z 941.4767 [M-H]-
(calcd. for C47H73O19, 941.4746), m/z 977.4533 [M þ Cl]- (calcd. for C47H74O1935Cl,
1
977.4513); H NMR (CD3OD, 500 MHz) dH ppm: 0.98 (m, Ha-1), 1.60 (m, Hb-1), 1.68 (m,
Ha-2), 1.90 (m, Hb-2), 3.14 (dd, J ¼ 4.5 and 12.0 Hz, H-3), 0.79 (m, H-5), 1.42 (m, Ha-6),
1.56 (m, Hb-6), 1.32 (m, Ha-7), 1.53 (m, Hb-7), 1.58 (m, H-9), 1.88 (m, Ha-11), 1.91 (m,
Hb-11), 5.26 (br s, H-12), 1.11 (m, Ha-15), 1.90 (m, Hb-15), 1.69 (m, Ha-16), 1.96 (m, Hb-
16), 2.84 (dd, 4.0, 14.0, H-18), 1.11 (m, Ha-19), 1.74 (m, Hb-19), 1.41 (m, Ha-21), 1.39 (m,
Hb-21), 3.86 (m, H-22), 1.06 (s, H3-23), 0.85 (s, H3-24), 0.96 (s, H3-25), 0.86 (s, H3-26),
1.19 (s, H3-27), 0.96 (s, H3-29), 1.01 (s, H3-30), Glu: 4.37 (d, J ¼ 8.0 Hz, H-10), 3.56 (dd,
J ¼ 8.0 and 9.0 Hz, H-20), 3.77 (t, J ¼ 9.0 Hz, H-30), 3.86 (t, J ¼ 9.0 Hz, H-40), 3.69 (m, H-50),
Glc: 4.88 (d, J ¼ 8.0 Hz, H-100), 3.27 (dd, J ¼ 8.0 and 9.0 Hz, H-200), 3.38 (t, J ¼ 9.0 Hz, H-
300), 3.36 (t, J ¼ 9.0 Hz, H-400), 3.28 (m,H-500), 3.71 (overlapped, Ha-600), 3.83 (overlapped,
Hb-600), Ara: 5.20 (br s, H-1000), 4.02 (br s, H-2000), 3.81 (br d, J ¼ 3.0 Hz, H-3000), 4.40 (m, H-
4000), 3.65 (dd, J ¼ 5.5 and 11.5 Hz, Ha-5000), 3.70 (dd, J ¼ 5.5 and 11.5 Hz, Hb-5000); 13C NMR
(CD3OD, 125 MHz) dC ppm: 39.8 (C-1), 26.9 (C-2), 90.9 (C-3), 40.2 (C-4), 57.0 (C-5), 19.3
(C-6), 34.0 (C-7), 43.3 (C-8), 48.8 (C-9), 37.9 (C-10), 24.5 (C-11), 123.7 (C-12), 144.6 (C-13),
40.7 (C-14), 28.5 (C-15), 17.4 (C-16), 53.6 (C-17), 44.0 (C-18), 46.9 (C-19), 32.1 (C-20),
42.9 (C-21), 72.5 (C-22), 28.5 (C-23), 17.0 (C-24), 15.9 (C-25), 17.9 (C-26), 26.8 (C-27),
181.0 (C-28), 33.6 (C-29), 25.2 (C-30), Glu: 106.3 (C-10), 76.5 (C-20), 82.1 (C-30), 75.4 (C-
40), 78.3 (C-50), 176.5 (C-60), Glc: 104.3 (C-100), 75.6 (C-200), 77.9 (C-300), 71.1 (C-400), 78.2
(C-500), 62.2 (C-600), Ara: 108.3 (C-1000), 81.9 (C-2000), 79.3 (C-3000), 87.2 (C-4000), 63.3 (C-5000).

NATURAL PRODUCT RESEARCH
7
3.3.2. Aramatoside B (2)
25
White amorphous powder, ½aꢀD : ꢁ38.2ꢂ (c 0.1, MeOH); HR-ESI-MS: m/z 941.4768 [M-H]-
(calcd. for C47H73O19, 941.4746), m/z 977.4536 [Mþ Cl]- (calcd. for C47H74O1935Cl,
1
977.4513); H NMR (CD3OD, 500MHz) dH ppm: 0.96 (m, Ha-1), 1.60 (m, Hb-1), 1.73 (m,
Ha-2), 1.91 (m, Hb-2), 3.64 (m, H-3), 1.25 (m, H-5), 1.39 (m, Ha-6), 1.49 (m, Hb-6), 1.29 (m,
Ha-7), 1.61 (m, Hb-7), 1.64 (m, H-9), 1.92 (m, H2-11), 5.23 (br s, H-12), 1.01 (m, Ha-15), 1.89
(m, Hb-15), 1.61 (m, Ha-16), 1.90 (m, Hb-16), 2.92 (dd, 3.5, 15.5, H-18), 1.11 (m, Ha-19),
1.69 (m, Hb-19), 1.17 (m, Ha-21), 1.37 (m, Hb-21), 1.51 (m, Ha-22), 1.76 (m, Hb-22), 3.28
(m, Ha-23), 3.62 (m, Hb-23), 0.71 (s, H3-24), 0.99 (s, H3-25), 0.88 (s, H3-26), 1.17 (s, H3-27),
0.90 (s, H3-29), 0.97 (s, H3-30), Glu: 4.47 (d, J ¼ 8.0 Hz, H-10), 3.55 (dd, J ¼ 8.0 and 9.0 Hz,
H-20), 3.77 (t, J ¼ 9.0Hz, H-30), 3.84 (t, J ¼ 9.0 Hz, H-40), 3.72 (m, H-50), Glc: 4.84 (d,
J ¼ 8.0Hz, H-100), 3.28 (dd, J ¼ 8.0 and 9.0Hz, H-200), 3.37 (t, J ¼ 9.0 Hz, H-300), 3.35 (t,
J ¼ 9.0 Hz, H-400), 3.26 (m, H-500), 3.71 (overlapped, Ha-600), 3.84 (br d, J ¼ 12.0 Hz, Hb-600),
Ara: 5.20 (br s, H-1000), 4.02 (br s, H-2000), 3.80 (br d, J ¼ 2.5 Hz, H-3000), 4.39 (m, H-4000), 3.64
(dd, J ¼ 4.0 and 12.0Hz, Ha-5000), 3.70 (dd, J ¼ 4.0 and 12.0 Hz, Hb-5000); 13C NMR (CD3OD,
125 MHz) dC ppm: 39.5 (C-1), 26.3 (C-2), 83.1 (C-3), 43.9 (C-4), 48.2 (C-5), 19.0 (C-6), 33.6
(C-7), 40.5 (C-8), 49.0 (C-9), 37.7 (C-10), 24.5 (C-11), 122.6 (C-12), 146.6 (C-13), 43.1 (C-14),
29.2 (C-15), 24.6 (C-16), 48.2 (C-17), 43.4 (C-18), 48.0 (C-19), 31.8 (C-20), 35.6 (C-21), 34.3
(C-22), 65.0 (C-23), 13.4 (C-24), 16.5 (C-25), 18.3 (C-26), 26.5 (C-27), 181.0 (C-28), 33.9 (C-
29), 24.3 (C-30), Glu: 105.0 (C-10), 76.1 (C-20), 82.7 (C-30), 75.2 (C-40), 78.3 (C-50), 176.6 (C-
60), Glc: 104.6 (C-100), 75.6 (C-200), 78.0 (C-300), 71.1 (C-400), 78.3 (C-500), 62.2 (C-600), Ara:
108.3 (C-1000), 82.0 (C-2000), 79.4 (C-3000), 87.1 (C-4000), 63.3 (Ara C-5000).
4. Conclusions
Nine oleanane-type triterpene saponins (1-9) including two new compounds (1 and 2)
were isolated from Aralia armata leaves. Their structures were elucidated by analysis
of HR-ESI-MS, NMR spectral data, and comparison with those reported in the literature.
Compounds 6-9 displayed great cytotoxic activity towards HT29, A2058, and A549 cell
lines (IC50 from 2.01 0.17 to 18.8 1.17 mM) in compared to positive control (irinote-
can hydrochloride, IC50 from 1.27 0.56 to 10.3 1.32 mM). Compounds 1-5 were con-
sidered as inactivity in our experiments. The results suggest that saponins containing
3b-hydroxyolean-12-ene-28-oic moiety could be potential cytotoxic agents against
HT29, A2058, and A549 cell lines.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Funding
This research is funded by Vietnam National Foundation for Science and Technology
Development (NAFOSTED) under grant number 104.01-2017.08.

8
P. H. YEN ET AL.
ORCID
SeonJu Park
Seung Hyun Kim
http://orcid.org/0000-0002-0532-5977
http://orcid.org/0000-0003-2613-0674
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