Triterpenoid saponins with hepatoprotective effects from the fresh leaves of Metapanax delavayi

Article abstract of DOI:10.1080/14786419.2018.1512987

The fresh leaves of Metapanax delavayi (Araliaceae) have been used as a common wild vegetable for salad and soup, and also herbal tea by the local people living in its growing areas of Yunnan province, China. Detailed chemical investigation led to the identification of a new triterpenoid saponin, 3-O-α-L-arabinopyranosyl-28-O-β-D-glucopyranosyl-(1→6)-O-β-D-glucopyranosyl-3β-hydroxyolean-12-ene-28,29-dioic acid (1) from the fresh leaves, together with 11 known compounds, including six triterpenoid saponins (2–7), two caffeoylquinic acid derivatives (8–9), and three flavonoid glycosides (10–12). Their structures were determined on the basis of spectroscopic analysis and acidic hydrolysis. Compounds 3–5 and 8–12 were isolated from M. delavayi for the first time. Moreover, the known saponins 3-O-β-D-xylopyranosyl-3β-hydroxyolean-12-ene-28,29-dioic acid (3) and yiyeliangwanoside IV (5) exhibited protective effects on HepG2 cells damaged by the alcohol intakes, at a concentration of 1.0 μg/mL. The results indicated M. delavayi is an ideal dietary vegetable and herbal tea with potential hepatoprotective activity. (Figure presented.).

Full text of DOI:10.1080/14786419.2018.1512987

Natural Product Research
Formerly Natural Product Letters
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Triterpenoid saponins with hepatoprotective
effects from the fresh leaves of Metapanax delavayi
Xin Wei, Da-Fang Gao, Yuko Abe, Yoshihisa Tanaka, Hong-Tao Zhu, Dong
Wang, Chong-Ren Yang & Ying-Jun Zhang
To cite this article: Xin Wei, Da-Fang Gao, Yuko Abe, Yoshihisa Tanaka, Hong-Tao Zhu, Dong
Wang, Chong-Ren Yang & Ying-Jun Zhang (2018): Triterpenoid saponins with hepatoprotective
effects from the fresh leaves of Metapanaxꢀdelavayi, Natural Product Research, DOI:
10.1080/14786419.2018.1512987
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NATURAL PRODUCT RESEARCH
https://doi.org/10.1080/14786419.2018.1512987
Triterpenoid saponins with hepatoprotective effects
from the fresh leaves of Metapanax delavayi
a
c
c
a,d
Xin Weia,b , Da-Fang Gao , Yuko Abe , Yoshihisa Tanaka , Hong-Tao Zhu
,
#
#
Dong Wanga,d, Chong-Ren Yanga and Ying-Jun Zhanga,d
aState Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of
b
Botany, Chinese Academy of Sciences, Kunming, People’s Republic of China; Guiyang University of
c
Chinese medicine, Guiyang, People’s Republic of China; Research and Development Center, Asahi
d
Breweries, LTD, Moriya, Ibaraki, Japan; Yunnan Key Laboratory of Natural Medicinal Chemistry,
Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, People’s Republic of China
ABSTRACT
ARTICLE HISTORY
Received 23 April 2018
Accepted 14 August 2018
The fresh leaves of Metapanax delavayi (Araliaceae) have been
used as a common wild vegetable for salad and soup, and also
herbal tea by the local people living in its growing areas of
Yunnan province, China. Detailed chemical investigation led to
the identification of a new triterpenoid saponin, 3-O-a-L-arabino-
pyranosyl-28-O-b-D-glucopyranosyl-(1!6)-O-b-D-glucopyranosyl-
3b-hydroxyolean-12-ene-28,29-dioic acid (1) from the fresh
leaves, together with 11 known compounds, including six triter-
penoid saponins (2–7), two caffeoylquinic acid derivatives (8–9),
and three flavonoid glycosides (10–12). Their structures were
determined on the basis of spectroscopic analysis and acidic
hydrolysis. Compounds 3–5 and 8–12 were isolated from M.
delavayi for the first time. Moreover, the known saponins 3-O-
b-D-xylopyranosyl-3b-hydroxyolean-12-ene-28,29-dioic acid (3)
and yiyeliangwanoside IV (5) exhibited protective effects on
HepG2 cells damaged by the alcohol intakes, at a concentration
of 1.0 mg/mL. The results indicated M. delavayi is an ideal dietary
vegetable and herbal tea with potential hepatoprotec-
tive activity.
KEYWORDS
Araliaceae; Metapanax
delavayi; triterpenoid
saponins; hepatoprotective
activity
CONTACT Ying-Jun Zhang
zhangyj@mail.kib.ac.cn
Kunming Institute of Botany, Chinese Academy of
Sciences, Kunming, 650201, People’s Republic of China
#These authors contributed equally to this work.
Supplemental data for this article can be accessed at https://doi.org/10.1080/14786419.2018.1512987.
ß 2018 Informa UK Limited, trading as Taylor & Francis Group

2
X. WEI ET AL.
1. Introduction
Alcohol is recognized commonly as one of the most causes for chronic liver disorders
(Diehl 2002). As the incidence of excessive drinking increases rapidly, alcoholic
liver disease (ALD) has caught more and more attention from the physicians and
pharmacists. In general, ALD showed varying situations among different individuals
at different stages (Diehl 2002). The early situation of ALD was fatty liver, and then
it developed as cirrhosis (Diehl 2002). The standard clinical treatments targeting ALD
involves the control of alcohol intake and nutritional therapies, however, the available
drugs for ALD are scarce (Arteel et al. 2003).
The genus Metapanax consisting of only two species, M. delavayi and M. davidii,
was classified to be a new genus of Araliaceae family by Fordin in 1992 (Wen and
Frodin 2001). Both species are distributed and cultivated in some areas of the western
and southwestern China (Fang 2006). The leaves of M. delavayi have been used not
only as a common wild vegetable for preparing salad and soup, but also as a substitu-
tion of herbal tea. Moreover, the local people of its growing areas also use the leaves
to treat bruises, rheumatism, and joint pain (Fang 2006).
Previously, a series of triterpenoid saponins were reported from the leaves of
M. delavayi and the barks of M. davidii (Kasai et al. 1987; Yu and Xiao 1990, 1992;
Yu et al. 1994, 1995a, 1995b). As part of our continuing research on chemical con-
stituents of edible plants (Wang et al. 2007), the leaves of M. delavayi was studied
chemically. This led to the isolation of one new triterpenoid saponin (1), together
with 11 known compounds, including six triterpenoid saponins (2–7), two caffeoyl-
quinic acid derivatives (8–9), and three flavonoid glycosides (10–12). Since triterpe-
noid saponins were reported to be involved to the hepato-protective activity
(Kinjo et al. 1999), most of the isolates, 1–8 and 10–12 were evaluated for their
protective effects on liver cells damaged by the alcohol intakes, using the HepG2
cell survival assay. Meanwhile, the isolation and structural elucidation of these
compounds on the basis of extensive spectroscopic methods and acidic hydrolysis
are presented.
2. Results and discussion
The MeOH extract of the leaves of M. delavayi was subjected to repeated
column chromatography (CC) over Sephadex LH-20, MCI-gel CHP20P, silica gel and
Rp-18 to afford a new saponin 1. In addition, 11 known compounds including six
triterpenoid saponins, 3-O-a-L-arabinopyranosyl-3b-hydroxyolean-12-ene-28,29-dioic
acid (2) (Yu et al. 1995a), 3-O-b-D-xylopyranosyl-3b-hydroxyolean-12-ene-28,29-dioic
acid (3) (Yu et al. 1995b), 3-O-a-L-arabinopyranoyl-3b-hydroxyolean-12-ene-28-oic acid
(4) (Higuchi and Kawasaki 1976), 3-O-(20-O-acetyl)-a-L-arabinopyranosyl-3b-hydroxy-
olean-12-ene-28,29-dioic acid (yiyeliangwanoside IV) (5) (Yu et al. 1994), 3-O-(40-O-ace-
tyl)-a-L-arabinopyranosyl-28-O-a-L-rhamnopyranosyl-(1!4)-O-b-D-glucopyrano-syl-(1!6)-
O-b-D-glucopyranosyl-3b-hydroxyolean-12-ene-28,29-dioic acid (yiyeliang wanoside X)
(6) (Yu et al. 1995a), and 3-O-(20-O-acetyl)-a-L-arabinopyranosyl-28-O-a-L-rhamnopyra-
nosyl-(1!4)-O-b-D-glucopyranosyl-(1!6)-O-b-D-glucopyranosyl-3b-hydroxy-olean-12-
ene-28,29-dioic acid (yiyeliangwanoside IX) (7) (Yu et al. 1995a), two caffeoylquinic

NATURAL PRODUCT RESEARCH
3
Figure 1. Compounds 1–12 isolated from M. delavayi.
acid derivatives, 4,5-di (8) (Hu and Chen 1997) and 3,4,5-tri (9) (Timmermann et al.
1983) -O-caffeoyl-quinic acid, and three flavonoid glycosides, quercetin-3-O-b-D-gluco-
pyranoside (10) (Veit et al. 1990), quercetin-3-O-b-D-galactopyranosyl-(1!6)-b-D-gluco-
pyranoside (11) (Waage and Hedin 1985), and kaempferol-3-O-b-D-glucopyranoside
(12) (Yu et al. 1989), were obtained. Their structures (Figure 1) were determined by
detailed spectroscopic analyses and by comparing with the literature data. The known
compounds 3–5 and 8–12 were isolated from M. delavayi for the first time.
Compound 1 was isolated as a white amorphous powder. Its molecular formula
was deduced to be C47H74O19 on the basis of HRTOFMS m/z 977.4515 [M þ Cl]– (calcd
for C47H74O19Cl, 977.4512) and the comprehensive analysis of 13 C NMR (DEPT) data.
The IR spectrum displayed absorption bands at 3427 cmꢀ1 (OH) and 1730 cmꢀ1
(C ¼ O). Acidic hydrolysis of 1 afforded L-arabinose and D-glucose as sugar residue,
which was confirmed by GC analysis of its corresponding trimethylsilylated L-cysteine
adducts. The 1 H and 13 C NMR data showed the presence of six tertiary methyls
at dH 1.24, 0.93, 0.87, 1.09, 1.20, and 1.42 (each 3 H, s) and an olefinic proton at
dH 5.47 (H-12), as well as 30 carbon signals including six methyls, 10 methylenes, five
methines, and nine quaternary carbons, corresponding to a triterpenoid aglycone.
In addition, three anomeric protons at dH 4.79 (d, J ¼ 7.0 Hz), 5.05 (d, J ¼ 7.8 Hz) and

4
X. WEI ET AL.
6.29 (d, J ¼ 8.2 Hz), together with 17 carbon signals arising from two hexosyls and one
pentosyl were observed, revealing 1 was a triterpenoid glycoside with one arabinosyl
and two glucosyl units. The above NMR data were closely related to those of 2 (Yu
et al. 1995a). However, compound 1 has two more glucosyl groups than 2. In the
HMBC spectrum of 1 (Figure S4), the correlations from the arabinosyl anomeric proton
at dH 4.79 (H-10) to the oxymethine at dC 88.8 (C-3) placed the arabinosyl moiety at
C-3, which was same to 2. Moreover, HMBC correlations from one glucosyl anomeric
proton at dH 5.05 (H-1000) to another glucosyl C-600 at dC 69.4 and the later glucosyl
H-100 at dH 6.29 to the aglycone C-28 at dC 176.5, revealed the linkage pattern of the
two glucosyl units and their location on C-28 of the triterpenoid skeleton.
In the ROESY spectrum of 1 (Figure S5), the obvious correlations of H-3 (dH 3.32)
with H-5 (dH 0.77), H-18 with Ha-21, and Hb-21 with H-30 positioned H-3 and the C-29
carboxyl group at a-orientation, respectively, due to the a-orientation for H-5 and H-18
by biogenetic considerations (Yu et al. 1995a). These were identical to those of 2.
On the basis of the above evidence, the structure of 1 was determined to be 3-O-a-L-
arabinopyranosyl-28-O-b-D-glucopyranosyl-(1!6)-b-D-glucopyranosyl-3b-hydroxy-olean-12-
ene-28,29-dioic acid.
Most of the isolates (1–8 and 10–12) and the MeOH extract of M. delavayi were
evaluated for the protective effects on HepG2 cells damaged by the alcohol intakes,
and the activity was expressed by the HepG2 cell survival (%). As shown in Figure S10,
the HepG2 cells adhered to the plate tightly and the outline of them was clear (Figure
S10a), while after incubated with EtOH, the cells did not adhered to the plate tightly
and their outline was not clear (Figure S10b). However, the adhesive property of
HepG2 cells was improved when the crude extract of M. delavayi (Figure S10c) were
added to the cells before the incubation with EtOH, and the outline of HepG2 cells
was clearer than those incubated with only EtOH. Compared with the EtOH (þ) control
group, the known saponins 3 and 5 showed obvious protective activity on HepG2
cells, at a concentration of 1.0 mg/mL (Table S1).
3. Experimental
3.1. General procedures
Optical rotations were performed on a P-1020 polarimeter (JASCO, Tokyo, Japan). IR
and UV spectra were measured on Bruker Tensor 27 spectrometer (Bruker, Karlsruhe,
Germany) with KBr pellets and Shimadzu UV-210A double-beam spectrophotometer
(Shimadzu, Kyoto, Japan). 1 D NMR spectra were recorded in C5D5N with a Bruker
DRX-500 instrument (Bruker, Karlsruhe, Germany) operating at 500 MHz for 1 H and
125 MHz for 13 C. 2 D NMR spectra were measured on a Bruker AV-600 instrument
(Bruker, Karlsruhe, Germany). Coupling constants were expressed in Hertz (Hz) and
chemical shifts were given on a ppm scale with tetramethylsilane (TMS) as internal
standard. FABMS were recorded on a VG Auto Spec-300 spectrometer (VG,
Manchester, UK) HRTOFMS was recorded on an API QSTAR time-of-flight spectro-
meter. Column chromatography (CC) were carried out over macro-porous resin (D101,
Cangzhou Baoeng Co. Ltd., China), silica gel (200–300 mesh, Qingdao Haiyang
Chemical Co. Ltd., China), MCI-gel CHP20P (75–100 mm, Mitsubishi, Japan), Rp-18

NATURAL PRODUCT RESEARCH
5
(40–63 mm, Merck, Germany) and Sephadex LH-20 (25–100 mm, Pharmacia, Sweden).
Thin-layer chromatography (TLC) was carried out on silica gel H-precoated plates was
purchased from Qingdao Haiyang Chemical Co., Ltd. (Qingdao, China) with CHCl3/
MeOH/H2O (8.5:1.5:0.1, 8:2:0.2 or 7:3:0.5, v/v/v) as developing solvents, and the spots
were detected by spraying with 10% H2SO4 in EtOH followed by heating.
3.2. Plant materials
The fresh leaves of M. delavayi were collected from the northern suburbs of Kunming,
Yunnan province, China, in October 2009, and identified by Professor Chong-Ren Yang
from Kunming Institute of Botany, Chinese Academy of Sciences. A voucher specimen
(No. KUN_0448104) was deposited in the Kunming Herbarium, Kunming Institute of
Botany, Chinese Academy of Sciences.
3.3. Extraction and isolation
The MeOH extract of the fresh leaves of M. delavayi was subjected to repeated CC
over Sephadex LH-20, MCI-gel CHP20P, silica gel and Rp-18 to afford compounds
1–12. Related details of this part are provided in Supporting Information.
3-O-a-L-arabinopyranosyl-28-O-b-D-glucopyranosyl-(1!6)-O-b-D-glucopyranosyl-3b-hydrox-
yolean-12-ene-28,29-dioic acid (1): White amorphous powder; [a]24 ꢀ18.5 (c 0.25, MeOH); IR
D
(KBr): ꢀmax 3427, 2929, 2879, 1931, 1632, 1548 cmꢀ1; UV kmax (MeOH) (log e): 202 (3.66) nm;
1H NMR (C5D5N, 500 MHz): dH 0.92 (m, H-1a), 1.50 (d, J¼ 12.9 Hz, H-1b), 1.89 (m, H-2a, 11a,
16a, 19a, 22a), 2.18 (m, H-2b, 11b), 3.32 (m, H-3, 18), 0.77 (d, J¼ 12.9 Hz, H-5), 1.28 (m, H-
6a), 1.41 (m, H-6b, 7b), 1.30 (m, H-7a), 1.62 (m, H-9), 5.47 (brs, H-12), 1.17 (m, H-15a), 2.24
(m, H-15b, 21b), 2.00 (m, H-16b), 2.55 (dd, J¼ 12.4, 15.3Hz, H-19b), 1.70 (m, H-21a), 1.96 (d,
J¼ 5.6 Hz, H-22b), 1.24 (s, H-23), 0.93 (s, H-24), 0.87 (s, H-25), 1.09 (s, H-26), 1.20 (s, H-27),
1.42 (s, H-30), 4.79 (d, J¼ 7.0 Hz, H-10), 4.46 (dd, J¼ 7.0, 7.8 Hz, H-20), 4.17 (m, H-30), 4.35 (m,
H-40), 4.33 (m, H-50a), 3.85 (d, J¼ 11.3 Hz, H-50b), 6.29 (d, J¼ 8.2 Hz, H-100), 4.16 (m, H-200,
4000), 4.23 (dd, J¼ 9.1, 9.0 Hz, H-300), 4.37 (m, H-400, 600a, 6000b), 4.10 (m, H-500), 4.77 (d,
J¼ 10.0 Hz, H-600b), 5.05 (d, J¼ 7.8 Hz, H-1000), 4.04 (dd, J¼ 7.8, 8.3 Hz, H-2000), 4.18 (m, H-3000),
3.91 (m, H-5000), 4.50 (d, J¼ 10.8 Hz, H-6000a); 13 C NMR (C5D5N, 125 MHz): dC 38.8 (C-1), 26.7
(C-2), 88.8 (C-3), 39.5 (C-4), 55.8 (C-5), 18.7 (C-6), 32.8 (C-7), 39.9 (C-8), 48.1 (C-9), 37.1 (C-10),
23.9 (C-11), 123.1 (C-12), 143.9 (C-13), 42.4 (C-14), 28.4 (C-15), 23.5 (C-16), 47.0 (C-17), 40.9
(C-18), 41.1 (C-19), 42.1 (C-20), 29.5 (C-21), 31.7 (C-22), 28.3 (C-23), 17.0 (C-24), 15.7 (C-25),
17.6 (C-26), 26.1 (C-27), 176.5 (C-28), 181.0 (C-29), 20.2 (C-30), 107.3 (C-10), 72.9 (C-20), 74.6
(C-30), 69.5 (C-40), 66.7 (C-50), 95.8 (C-100), 73.9 (C-200), 78.7 (C-300), 71.1 (C-400), 77.9 (C-500), 69.4
(C-600), 105.3 (C-1000), 75.2 (C-2000), 78.4 (C-3000), 71.7 (C-4000), 78.4 (C-5000), 62.7 (C-6000); FABMS
m/z 941 [M–H]–; HRTOFMS m/z 977.4515 [M þ Cl]– (calcd for C47H74O19Cl, 977.4512).
3.4. Acid hydrolysis and GC analysis of compound 1
The acid hydrolysis and GC analysis were performed using a previously described
method (Supporting Information) (Yu et al. 1995b). By comparing the retention times
of the sugar derivatives with those of the authentic sugars under the same conditions,

6
X. WEI ET AL.
the sugar unit of compound 1 was determined to be D-glucose (22.515 min), L-arabi-
nose (17.139 min) by compare with standard D-glucose (22.513 min) and L-glucose
(22.926 min), D-arabinose (17.662 min), and L-arabinose (17.102 min).
3.5. HepG2 cells survival assay
HepG2 cells was distributed (8 ꢁ 104 cells/100 mL in one well) in 96-well culture plate
and incubated at 37 ꢂC for 44 h. Then, the extract of M. delavayi (50 mg/mL, 10 mL),
compounds 1–8 and 10–12 (1.0 mg/mL, 10 mL) were added to the cells, respectively.
After incubated at 37 ꢂC for 4 h, EtOH/H2O (2:23, v/v) was added into and continue
incubated for 24 h. Cells treated without the extract and tested compounds, but only
EtOH/H2O (2:23, v/v) was the EtOH (þ) group. Afterwards, the medium of cells was
removed and changed to Alamar Blue/medium solution (10%, 200 mL). Finally, the
mixture incubated for 3 h after mixed thoroughly and measured fluorescence with
flurometric plate reader at 544 nm/590 nm as previously described (Lee et al. 2008).
The activity was expressed by HepG2 cell survival (%), and compared to the EtOH (þ)
group. The values were evaluated as a percentage of the EtOH (-) group that did not
contain the EtOH/H2O (2:23, v/v) and expressed as means SEM (n ¼ 3). Comparisons
between groups were performed using the Dunnett’s test, and p < 0.05 was
considered to be significant.
4. Conclusions
In conclusion, one new saponin 1, together with 11 known compounds (2–12) was
isolated and characterized from the fresh leaves of M. delavayi, which served as a com-
mon vegetable and substitution of herbal tea by the local people living in its growing
areas. The known saponins 3–5 and flavonoid glycosides 8–12 were isolated from the
titled plant for the first time. It is noted that the known saponins 3 (0.0021% for
extract) and 5 (0.0015% for extract) exhibited obvious protective effects on the HepG2
cells damage induced by the alcohol intake, at a concentration of 1.0 mg/mL. This is
the first report to present the hepatoprotective effects of M. delavayi and the genus
Metapanax. Our study provided the evidence for the rationality of the traditional uses
as vegetable and herbal tea of the titled plant. It is suggested that M. delavayi may
worth to be developed as healthy beverage, functional food, and potential therapeutic
agents for ALD.
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding
This work was supported by the National Natural Science Foundation of China (No. 31470429).

NATURAL PRODUCT RESEARCH
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