A new triterpenoid and a new glycoside from Pilea cavaleriei

Article abstract of DOI:10.1080/10286020.2012.702760

A new triterpenoid, 11α,12α-epoxy-3β-hydroxy-24-nor-olean- 4(23)-en-28,13β-olide (1), and a new glycoside, benzyl 2-O-β-d- apiofuranosyl-(1 → 2)-β-d-glucopyranosyl benzoate (2), together with eight known triterpenoids (3-10), were isolated from Pilea cavaleriei subsp. cavaleriei. Their structures were established on the basis of spectroscopic analysis including HR-ESI-MS, 1D NMR, and 2D NMR techniques. All compounds showed no anti-hepatitis C virus activity.

Full text of DOI:10.1080/10286020.2012.702760

Journal of Asian Natural Products Research
Vol. 14, No. 11, November 2012, 1032–1038
A new triterpenoid and a new glycoside from Pilea cavaleriei
Heng-Chun Rena, Ri-Dong Qina, Qi Wangab, Wei Chenga, Qing-Ying Zhanga and
Hong Lianga*
aState Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences,
Peking University, Beijing 100191, China; bDepartment of Molecular and Cellular Pharmacology,
School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
(Received 23 March 2012; final version received 11 June 2012)
A new triterpenoid, 11a,12a-epoxy-3b-hydroxy-24-nor-olean-4(23)-en-28,13b-olide
(1), and a new glycoside, benzyl 2-O-b-D-apiofuranosyl-(1 ! 2)-b-D-glucopyranosyl
benzoate (2), together with eight known triterpenoids (3–10), were isolated from
Pilea cavaleriei subsp. cavaleriei. Their structures were established on the basis of
spectroscopic analysis including HR-ESI-MS, 1D NMR, and 2D NMR techniques. All
compounds showed no anti-hepatitis C virus activity.
Keywords: Pilea cavaleriei subsp. cavaleriei; benzyl 2-O-b-D-apiofuranosyl-(1 ! 2)-
b-D-glucopyranosyl benzoate; 11a,12a-epoxy-3b-hydroxy-24-nor-olean-4(23)-en-
28,13b-olide; anti-hepatitis C virus activity
1. Introduction
none of the compounds showed anti-HCV
activity.
The genus Pilea belongs to the Urticaceae
family and widely distributed in tropical
and subtropical regions of the world [1].
In China, approximately 30 Pilea species
are used as traditional Chinese medicines
[2]. Pilea cavaleriei subsp. cavaleriei is a
common Zhuang folk medicine and used to
treat cough with lung heat, tuberculosis, and
traumatic injuries [3]. This paper deals with
the isolation and structural elucidation of a
new triterpenoid, 11a,12a-epoxy-3b-
hydroxy-24-nor-olean-4(23)-en-28,13b-
olide (1), and a new glycoside, benzyl 2-O-
b-D-apiofuranosyl-(1 ! 2)-b-D-glucopyra-
nosyl benzoate (2), together with eight
known triterpenoids (3–10). Compounds
3–10 were isolated from the genus
Pilea for the first time. Pentacyclic triter-
penoids had been reported possessing anti-
hepatitis C virus (anti-HCV) activity [4].
Thus, anti-HCV activity was evaluated and
2. Results and discussion
Compound 1 (Figure 1) was obtained as
colorless powder. The molecular formula
was assigned to be C29H42O4 based on (þ)-
HR-ESI-TOF-MS data at m/z 455.3161
[M þ H]þ. The 1H NMR spectrum showed
signals due to the protons of five tertiary
methyl groups at d 0.84 (3H, s), 0.93 (3H, s),
1.00 (3H, s), 1.10 (3H, s), and 1.14 (3H, s);
two exomethylene protons at d 5.08 (1H, s)
and 4.71 (1H, s); and three oxygenated
methine protons at d 4.04 (1H, dd, J ¼ 10.8
and 5.6 Hz), 3.06 (1H, br.s), and 3.05 (1H,
br.s). Besides, there were 21 overlapping
signals at d 1.19–2.34. The 13C NMR
spectrum exhibited 29 signals including 1
carbonyl carbon signal at d 179.2; 2
exocyclic double bond signals at d 102.9
and 151.8; 3 oxygenated methine signals
at d 72.9, 57.1, and 52.9; 1 oxygenated
*Corresponding author. Email: lianghong@bjmu.edu.cn
ISSN 1028-6020 print/ISSN 1477-2213 online
q 2012 Taylor & Francis
http://dx.doi.org/10.1080/10286020.2012.702760
http://www.tandfonline.com

Journal of Asian Natural Products Research
1033
Figure 1. Structures of 1 and 2.
quaternary carbon signal at d 87.5; 5 methyl
signals atd 33.2, 23.6, 19.7, 18.8, and14.3; 3
methine signals at d 49.7, 49.6, and 48.6; 5
quaternary carbon signals at d 43.8, 41.3,
40.7, 38.3, and 31.4; and 9 methylene
quaternary carbon signals at d 38.2, 37.8,
34.3, 32.2, 29.6, 27.0, 26.7, 21.3, and 20.3.
1H and 13C NMR spectral data of 1 were
that H-25 at d 0.84 correlated with C-1 at d
38.2, C-5 at d 49.7, C-9 at d 48.6, and C-10
at d 38.3; H-26 at d 1.10 correlated with C-7
Table 1. 1H and 13C NMR spectral data for 1
(CDCl3, TMS, d).
1
assigned based on H NMR, 13C NMR,
1
1H–1H COSY, HSQC, and HMBC analyses
(Table 1, Figure 2). 13C NMR spectrum
exhibited characteristic signals of epoxy-g-
lactones at d 52.9, 57.1, and 87.5 [5]. 1H–1H
COSY spectrum showed that H-23 at d 5.08
and 4.71 coupled with H-3 at d 4.04 and H-5
at d 1.56, respectively. In HMBC spectrum,
H-23 at d 5.08 and 4.71 correlated with C-3
at d 72.9, C-4 at d 151.8, and C-5 at d 49.7;
H-3 at d 4.04 correlated with C-4 at d 151.8
and C-23 at d 102.9; H-5 at d 1.56 correlated
with C-3 at d 72.9, C-4 at d 151.8, and C-23
at d 102.9, establishing the presence of an
exomethylene group at C-4. 1H–1H COSY
spectrum showed H-11 at d 3.05 coupled
with H-9 at d 1.71, and the HMBC spectrum
showed H-11 at d 3.05 correlated with C-8
at d 41.3, C-9 at d 48.6, C-10 at d 38.3, C-12
at d 57.1, and C-13 at d 87.5; H-9 at d 1.71
correlated with C-8 at d 41.3, C-10 at d 38.3,
C-11 at d 52.9, and C-12 at d 57.1,
suggesting the presence of 11,12-epoxy
group. HMBC spectrum showed that H-16
at d 2.15 and 1.33 and H-22 at d 1.67
correlated with C-28 at d 179.2 and C-17 at
d 43.8, indicating the presence of 28,13-
lactone moiety. HMBC spectrum showed
Position dC, DEPT
dH (J in Hz)
1
2
3
4
5
6
7
38.2, CH2
32.2, CH2
72.9, CH
151.8, C
49.7, CH
20.3, CH2
29.6, CH2
1.97, m; 1.35, m
2.07, m; 1.50, m
4.04, dd (10.8, 5.6)
1.56, d (13.2)
1.65, m; 1.49, m
1.34, m; 1.19, br.d
(12.8)
8
9
41.3, C
48.6, CH
38.3, C
1.71, m
10
11
12
13
14
15
16
17
18
19
20
21
22
23
25
26
27
28
29
30
52.9, CH
57.1, CH
87.5, C
3.05, br.s
3.06, br.s
40.7, C
27.0, CH2
21.3, CH2
43.8, C
49.6, CH
37.8, CH2 1.89, t (13.6); 1.62, m
31.4, C
34.3, CH2
26.7, CH2
102.9, CH2
14.3, CH3
19.7, CH3
18.8, CH3
179.2, C
1.65, m
2.15, m; 1.33, m
2.34, dd (13.6,3.2)
1.36, 2H, m
1.67, 2H, m
5.08, s; 4.71, s
0.84, 3H, s
1.10, 3H, s
1.14, 3H, s
23.6, CH3
33.2, CH3
0.93, 3H, s
1.00, 3H, s

1034
H.-C. Ren et al.
Figure 2. (a) COSY (bold lines) and key HMBC (arrows) correlations of 1; (b) selected NOE
experiments of 1.
at d 29.6, C-8 at d 41.3, C-9 at d 48.6, and C-
14 at d 40.7; H-27 at d 1.14 correlated with
C-8 at d 41.3, C-14 at d 40.7, and C-15 at d
27.0; H-29 at d 0.93 correlated with C-20 at
d 31.4 and C-19 at d 37.8; H-30 at d 1.00
correlated with C-20 at d 31.4, C-19 at d
37.8, and C-29 at d 23.6, suggesting the
presence of five methyl groups at C-10, C-8,
C-14, C-20, and C-20, respectively. The
orientation of H-3 was deduced as a from
the large coupling constant at d 4.04 (1H,
dd, J ¼ 10.8 and 5.6 Hz), then 3-OH was
b-oriented. Moreover, the NOE correlations
between H-11 and Me-25, H-11 and Me-26
suggested the configuration of an 11a,12a-
epoxide. Thus, the structure of compound 1
was determined as 11a,12a-epoxy-3b-
hydroxy-24-nor-olean-4(23)-en-28,13b-
olide. The NMR spectral data of compound
1 were similar to those of ilelatifol A [6],
but 2-OH was absence in compound 1
compared to ilelatifol A.
the presence of one oxygenated methylene
groupandtwosugarmoieties.The13CNMR
spectrum exhibited 25 signals, of which one
carbonyl carbon signal at d 168.2 and 12
aromaticcarbon signals were assigned tothe
aglycone, and the remaining signals
belonged to the two sugar moieties. 1H and
13C NMR spectral data of 2 were assigned
based on 1H NMR, 13C NMR, 1H–1H
COSY, HSQC, HMBC, and 1D-TOCSY
analyses (Table 2). In HMBC spectrum, H-6
at d 7.69 correlated with C-7 at d 168.2 and
C-2 at d 157.6; H-3 at d 7.24 correlated with
C-2 at d 157.6, C-5 at d 122.7, and C-1 at d
123.0; H-70 at d 5.36 correlated with C-7 at d
168.2, C-10 atd 137.6,andC-20, 60 atd 129.3,
indicating that the benzyl group was linked
to C-7, and the structure of aglycone is
benzyl 2-hydroxy-benzoate. Analysis of the
1H and 13C NMR spectral data from the
sugar moiety indicated the existence of one
hexose and one pentose, which was further
confirmed by the detection of glucose and
apiose after acid hydrolysis of 2. D-Glucose
was determined by measuring the optical
rotationas dextrorotationafter acid hydroly-
sis and separation, and the anomeric proton
of glucose at d 5.11 (1H, d, J ¼ 7.2 Hz)
suggested its b-configuration. The remain-
ing five carbon signals at d 111.2, 78.0, 80.3,
75.1, and 65.6 could be assigned to another
sugar apiose [7] from HMBC and COSY
correlations (Figure 3). The orientation of
apiose was deduced as b by the singlet of
anomeric proton, whilea-orientationshould
be the doublet (J ¼ 4.5 Hz) [8]. D-Configur-
ation was determined by comparing the
anomeric carbon signal with literature, in
Compound 2 (Figure 1) was obtained as
colorless powder. Its molecular formula was
assignedtobe C25H30O12 based on(þ)-HR-
ESI-TOF-MS at m/z 545.1636 [M þ Na]þ.
The 1H NMR spectrum showed nine
aromatic proton signals including an ortho-
disubstituted benzyl signals at d 7.69 (1H, d,
J ¼ 7.6 Hz), 7.06 (1H, t, J ¼ 7.6 Hz), 7.50
(1H, t, J ¼ 7.6 Hz), 7.24 (1H, d, J ¼ 7.6 Hz)
and a mono-substituted benzyl signals at d
7.49 (2H, d, J ¼ 7.2 Hz), 7.38 (2H, t,
J ¼ 7.2 Hz), and 7.33 (1H, t, J ¼ 7.2 Hz)
1
by the analysis of H–1H COSY corre-
lations. The signals at d 5.36 (2H, br.s), 5.44
(1H, br.s), 5.11 (1H, d, J ¼ 7.2 Hz) and 11
overlapped signals at d 3.44–3.99 inferred

Journal of Asian Natural Products Research
1035
Table 2. 1H and 13C NMR spectral data for 2 (MeOD, TMS, d).
2
Position
dC, DEPT
dH, Mult. (J in Hz)
HMBC correlation
1
2
123.0, C
157.6, C
3
4
5
6
116.7, CH
134.4, CH
122.7, CH
131.8, CH
168.2, C
7.24, d (7.6)
7.50, t (7.6)
7.06, t (7.6)
7.69, d (7.6)
C-1/C-2/C-4/C-5
C-2/C-3/C-5/C-6
C-1/C-3/C-4/C-6
C-7/C-2/C-4
7
10
20
30
40
50
600
700
100
200
300
4
137.6, C
129.3, CH
129.5, CH
129.1, CH
129.5, CH
129.3, CH
68.0, CH2
100.8, CH
80.1, CH
77.9, CH
71.1, CH
78.0, CH
62.4, CH2
7.49, d (7.2)
7.38, t (7.2)
7.33, t (7.2)
7.38, t (7.2)
7.49, d (7.2)
5.36, br.s
5.11, d (7.2)
3.67, dd (7.6,7.2)
3.61, t (7.6)
3.44, m
C-70/C-40/C-30,50
C-10/C-40/C-20,60
C-20,60
C-10/C-40/C-20,60
C-70/C-40/C-30,50
C-7/C-10/C-20,60
C-2/C-300
C-100/C-300/C-400
C-400/C-200/C-500
C-200/C-300/C-500
C-300/C-600
500
600
3.44, m
3.87, d (9.2)
3.69, d (9.2)
5.44, br.s
C-500
C-500
1000
2000
3000
4000
111.2, CH
78.0, CH
80.3, C
C-200/C-4000
3.99, br.s
C-1000/C-4000/C-5000
75.1,CH2
3.90, d (9.0)
3.69, d (9.0)
3.53, s
C-5000/C-2000/C-1000
C-5000/C-2000
C-2000/C-3000/C-4000
5000
65.6, CH2
which b-D configuration located at d 110.2
while b-L at d 105.4 [9]. In the HMBC
spectrum, H-100 at d 5.11 correlated with C-2
at d 157.6, H-1000 at d 5.44 correlated with
C-200 carbon signal at d 80.1, indicating that
the apiosyl group was linked to C-200 of
glucose, and the glucosyl group was linked
to C-2 of the aglycone. Thus, the structure of
2 was determined as benzyl 2-O-b-D-
apiofuranosyl-(1 ! 2)-b-D-glucopyranosyl
benzoate. The NMR spectral data of 2 were
similar to those of benzyl 2-O-b-D-apiofur-
anosyl-(1 ! 2)-b-D-glucopyranosyl-2,6-
dihydroxy-benzoate, especially in B-ring
and disaccharide moiety, the difference of
NMR data in A-ring was caused by the lack
of6-OHin2, comparedtothe literature [10].
Compounds 3–10 were identified as
friedelin [11], 3beta-acetoxy-hop-22(29)-
ene [12], 3beta-friedelinol [13], 3beta-
hydroxyglutin-5-ene [14], 3beta-hydroxy-
hop-22(29)-ene [15], oleanolic acid [16],
ursolic acid [17], and squalene [18],
respectively, on the basis of spectroscopic
analysis.
5'
5
7'
1
B
4'
A
1
O
2'
6''
HOH2C
7
2
O
O
5''
O
O
HO
HO
1''
3''
O
4'''
5'''
1'''
2'''
OH
HO
OH
Figure 3. COSY (bold lines) and key HMBC
(arrows) correlations of 2.

1036
H.-C. Ren et al.
Table 3. Anti-HCV activities of selected compounds.
HCV inhibition (%)
VSV inhibition (%)
Compound
1 mM
5 mM
1 mM
5 mM
Echincystic acid
10.33
0
0
53.58
32.45
0
5.12
4.19
37.06
9.16
0
0
0
0
1
3
4
5
6
7
15.94
20.41
26.47
37.30
24.15
19.43
28.02
26.49
27.06
22.22
0
0.84
13.66
0
Reference compound.
Pentacyclic triterpenoids had been
reported possessing the anti-HCV activity.
Thus, anti-HCV activity of compounds 1
and 3–7 was evaluated using the method
reported [4] and echincystic acid as
reference compound. The results were
summarized in Table 3. None of the
compounds showed anti-HCV activity.
USA). Fractions were monitored by TLC,
and spots were visualized on precoated
silica gel plates by spraying 10% H2SO4 in
ethanol followed by heating.
3.2 Plant material
The whole plants were collected from
Liuzhou city, Guangxi Province of China
in July 2009 and identified as Pilea
cavaleriei Levi. subsp. cavaleriei by Prof.
De-Hai Qin, Guangxi Institute of Tra-
ditional Chinese Medicine. A specimen
(no. NME20090701) is deposited at the
Department of Natural Medicines, School
of Pharmaceutical Sciences, Peking Uni-
versity Health Science Center.
3. Experimental
3.1 General experimental procedures
UV spectra were acquired on a Cary 300
spectrophotometer (Varian, Palo Alto, CA,
USA). IR data were measured on a Nicolet
NEXUES-470 FT-IR instrument (Nicolet,
Austin, TX, USA). HR-ESI-TOF-MS were
recorded on a Bruker APEX IV FT-MS
(7.0T) mass spectrometer (Bruker, Bill-
erica, MA, USA). 1D and 2D NMR spectra
were taken on a Bruker AV 400 spec-
trometer (Bruker, Fllanden, Switzerland)
with tetramethylsilane (TMS) as internal
standard. Thin layer chromatography (TLC)
and column chromatography (CC) were
performed on silica gel plates and silica gel
G separately (TLC: GF254 and CC: 200–
300 mesh; Qingdao Marine Chemical Co.,
Ltd, Qingdao, China), Sephadex LH-20
(GE Healthcare, Uppsala, Sweden), and
SciBioChem MCI GEL (SBC MCI GEL,
75–100 mm, Chengdu Kepubio Co., Ltd.,
Chengdu, China). Solvents were of analyti-
cal grade, which were purchased from
3.3 Extraction and isolation
The air-dried and powdered whole plants of
P. cavaleriei (10 kg) were percolated with
95% aqueous EtOH and 50% aqueous EtOH
at room temperature, respectively. After
evaporation of the solvent under reduced
pressure, the residues were mixed and
suspended in water and then successively
partitioned with petroleum ether, EtOAc,
and n-BuOH to afford 235.0 g, 35.0g, and
175.0 g of extracts, respectively. The pet-
roleum ether extract (232.0g) was subjected
to silica gel CC and eluted with petroleum
ether–acetone(20:1to1:5,v/v)togiveeight
fractions (Fr.1–Fr.8). Fr. 5 (27.0 g) was
further separated on MCI CC eluted with
MeOH–H2O (70:30 to 100:0, v/v) to yield
four subfractions (Fractions A–D). Fraction
Beijing
Chemical
Corporation
(Beijing, China). Bright-Glo reagent was
purchased from Promega (Madison, WI,

Journal of Asian Natural Products Research
1037
B (80% aqueous MeOH extracts, 2.3 g) was
separated on silica gel CC eluted with
petroleum ether–acetone (4:1, v/v), and
then purified by Sephadex LH-20 CC eluted
with CHCl3–MeOH (1:1) to afford 1
(30.0 mg). Fr. 8 (32.0 g) was further
separated on MCI CC eluted with MeOH–
H2O (50:50 to 100:0, v/v) to get five
subfractions (Fractions I–V). Fraction III
(70% aqueous MeOH extracts, 4.2 g) was
separated on silica gel CC eluted with
petroleum ether–acetone (10:1, v/v), and
then purified by Sephadex LH-20 CC eluted
with MeOH to afford 2 (12.0 mg). Fr. 1
(21.0 g) was further separated on repeated
silica gel CC eluted with petroleum ether–
acetone (50:1 to 5:1, v/v) to afford 3
(500.0mg), 4 (8.0mg), 5 (20.0 mg), and 10
(20.0 mg). Fr. 2 (14.2 g) was separated on
repeated silica gel CC eluted with petroleum
ether–acetone (30:1 to 3:1, v/v), and then
purified by Sephadex LH-20 CC eluted with
CHCl3–MeOH (1:1) to afford 6 (15.0 mg).
Fr. 3 (36.6 g) was separated on repeated
silica gel CC eluted with petroleum ether–
acetone(10:1–1:3,v/v),andthenpurifiedby
Sephadex LH-20 CC eluted with (CHCl3–
MeOH, 1:1) to afford 7 (12.0 mg). Fr. 6
(21.0 g) was further separated on MCI CC
eluted with MeOH–H2O (70:30 to 100:0,
v/v), and then purified by Sephadex LH-20
CC eluted with MeOH to afford 8 (10.0 mg)
and 9 (20.0 mg).
1H and 13C NMR spectral data, see Table 2;
ESI-MS m/z 545 [M þ Na]þ; HR-ESI-MS
m/z 545.1636 [M þ Na]þ (calcd for
C25H30O12Na, 545.1635).
3.4 Acid hydrolysis and analysis of
sugars of compound 2
Compound 2 (4.0mg) was hydrolyzed with
5% HCl (3ml) at 708C for 6 h. After being
cooled, thepHvalueofreactionmixturewas
adjusted to 7.0, and then subjected the
mixture to Sephadex LH-20 CC eluted with
MeOH to afford glucose and apiose (not
pure). The sugars were identified as glucose
by co-TLC (BuOH:CH3COOH:H2O, 4:2:1)
with authentic glucose and reference apiose,
obtained from the hydrolysis of authentic
(2)-syringaresnol-4-O-b-D-apiofuranosyl-
(1 ! 2)-b-D-glucopyranoside.
3.5 Anti-HCVpp infection assays
For compound library screening, infections
were performed in 96-well plates by mixing
HCVpp or VSVpp with 5 £ 103 Huh-7
cells/well in the presence or absence of test
inhibitors, followed by incubation at 378C.
Luciferase activity, reflecting the degree of
the pseudoparticles into host cells, was
measured after the infection of 3 days using
the Bright-Glo reagent (Promega). Test
compounds were serially diluted to give a
final concentration at 1 and 5 mM in 1%
dimethyl sulfoxide (DMSO). Maximum
activity (100% of control) and background
were derived from control wells containing
DMSO alone or from uninfected wells,
respectively. The individual signals in each
of the compound test wells were then
divided by the averaged control values
(wells lacking inhibitor), after background
subtraction, and multiplied by 100% to
determine percent activity. The correspond-
ing % inhibition values were then calcu-
lated by subtracting this value from 100.
The specificity of the compounds for
inhibiting HCV was determined by evalu-
ating the inhibition of VSVpp infection in
parallel.
3.3.1 11a,12a-Epoxy-3b-hydroxy-24-
nor-olean-4(23)-en-28,13b-olide (1)
Colorless powder; IR (KBr) nmax (cm21):
3495, 2942, 1758, 1649, 1146, and 931; for
1H and 13C NMR spectral data, see Table 1;
EI-MS m/z 454 [M]þ; HR-ESI-MS m/z
455.3161 [M þ H]þ (calcd for C29H43O4,
455.3161).
3.3.2 Benzyl 2-O-b-D-apiofuranosyl-
(1 ! 2)-b-D-glucopyranosyl benzoate (2)
Colorless powder; UV lMeOH (nm) (log e):
286 (3.98); IR (KBr) nmax (cm21): 3392,
2930, 1715, 1600, 1490, 1251, and 1076; for

1038
H.-C. Ren et al.
[9] T. Ishii and M. Yanagisawa, Carbohydr.
Res. 313, 189 (1998).
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