Three new labdane-type diterpene glycosides from fruits of Rubus chingii and their cytotoxic activities against five humor cell lines

Article abstract of DOI:10.1016/j.fitote.2015.01.007

Three new labdane-type diterpene glycosides, 15,18-di-O-β-d-glucopyranosyl-13(E)-ent-labda-7(8),13(14)-diene-3β,15,18-triol (1), 15,18-di-O-β-d-glucopyranosyl-13(E)-ent-labda-8(9),13(14)-diene-3β,15,18-triol (2), and 15-O-β-d-apiofuranosyl-(1 → 2)-β-d-glucopyranosyl-18-O-β-d-glucopyranosyl-13(E)-ent-labda-8(9),13(14)-diene-3β,15,18-triol (3), were isolated from the fruits of Rubus chingii. Their structures were elucidated on the basis of spectroscopic data and chemical methods. The cytotoxic activities of compounds 1-3 were evaluated against five human tumor cell lines (HCT-8, BGC-823, A549, and A2780). Compounds 3 showed cytotoxic activity against A549 with an IC₅₀ value of 2.32 μM.

Full text of DOI:10.1016/j.fitote.2015.01.007

FITOTE-03105; No of Pages 4
Fitoterapia xxx (2015) xxx–xxx
Contents lists available at ScienceDirect
Fitoterapia
journal homepage: www.elsevier.com/locate/fitote
1Q2 Three new labdane-type diterpene glycosides from fruits of Rubus chingii and
2
their cytotoxic activities against five humor cell lines
c,
3Q3 Ruijian Zhong a, Qing Guoa,b, Guoping Zhoua, Huizheng Fu a,
⁎
⁎
, Kaihua Wan OOF
a
4
5
6
Jiangxi Provincial Institute for Drug and Food Control, Nanchang 330029, China
Jiangxi University of Traditional Chinese Medicine, Nanchang 330006, China
Drug Adverse Reaction Monitoring Center of Jiangxi, Nanchang 330046, China
b
c
7
9
a r t i c l e i n f o
a b s t r a c t
104
11
12
13
Article history:
Three new labdane-type diterpene glycosides, 15,18-di-O-β-D-glucopyranosyl-13(E)-ent-labda-
7(8),13(14)-diene-3β,15,18-triol (1), 15,18-di-O-β-D-glucopyranosyl-13(E)-ent-labda-8(9), 15
13(14)-diene-3β,15,18-triol (2), and 15-O-β-D-apiofuranosyl-(1 → 2)-β-D-glucopyranosyl-18- 16 Q4
O-β-D-glucopyranosyl-13(E)-ent-labda-8(9),13(14)-diene-3β,15,18-triol (3), were isolated from 17
the fruits of Rubus chingii. Their structures were elucidated on the basis of spectroscopic data and 18
chemical methods. The cytotoxic activities of compounds 1–3 were evaluated against five human 19
tumor cell lines (HCT-8, BGC-823, A549, and A2780). Compounds 3 showed cytotoxic activity 20
Received 27 November 2014
Accepted in revised form 7 January 2015
Available online xxxx
23
24
25
26
27
Keywords:
Rubus chingii
Labdane-type
Diterpene glycosides
Cytotoxic activity
against A549 with an IC50 value of 2.32 μM.
21
© 2015 Published by Elsevier B.V. 22
28
1. Introduction
apiofuranosyl-(1
→
2)-β-D-glucopyranosyl-18-O-β-D-glucopy- 4Q48
ranosyl-13(E)-ent-labda-8(9),13(14)-di-ene-3β,15,18-triol (3), 45
were isolated from the fruits of R. chingii. Reported herein are 46
the isolation, structure elucidation and biological activity of 47
29
30
31
32
Rubus chingii Hu, belonging to the family Rosaceae, is
distributed widely in Jiangxi, Zhejiang, Fujian, and Guangxi
Provinces of mainland China. Its fruits are used as a Chinese
medicine for treating enuresis with renal asthenia, frequent
these compounds.
48
49
50
3Q3 6 urination, premature ejaculation, and impotence [1]. Previous
2. Experimental
34
35
36
37
38
39
phytochemical studies on R. chingii have led to the isolation of
flavonoids [2], triterpenoids [3–6], organic acids [7,8], sterols
[3,7], and alkaloids [9]. In our preliminary screening, the n-
BuOH part of the 70% EtOH extract of the fruits of R. chingii
showed significant anticancer activity. As part of program to
discover biologically significant anticancer properties from plant
2.1. General experimental procedures
Optical rotations were measured on an Autopol IV-T/V 51
(Rudolph Research Analytical, New Jersey, USA). UV spectra 52
were recorded in MeOH on a Jasco V650 spectrophotometer 53
(JASCO, Inc., Easton, Maryland, USA). The 1H (600 MHz), 13C 54
(150 MHz), and 2D NMR spectra were recorded on a Bruker 55
4Q0 7 resources has led to the isolation of three new compounds,
41
42
43
15,18-di-O-β-D-glucopyranosyl-13(E)-ent-labda-7(8),13(14)-
diene-3β,15,18-triol U(1), 1N5,18-dCi-O-β-DO-glucoRpyranoRsyl-13E(E)- CTED PR
AVANCE III 600 instrument using TMS (Tetramethylsilane) as an 56
ent-labda-8(9),13(14)-diene-3β,15,18-triol (2), and 15-O-β-D-
internal reference (Bruker Company, Massachusetts, USA). 57
HRTOFMS data were obtained on an Agilent 7890-7000A mass 58
spectrometer (Agilent Technologies, Santa Clara, USA). Prepara- 59
tive HPLC (high performance liquid chromatography) was 60
conducted with an Agilent Technologies 1200 series instrument 61
with a MWD detector using a YMC-pack ODS (Octadecylsilyl)-A 62
column (5 μm, 250 × 20 mm). Column chromatography was 63
⁎
Corresponding authors.
E-mail addresses: fhzfhz620@sohu.com (H. Fu), kk2008317@163.com
(K. Wan).
http://dx.doi.org/10.1016/j.fitote.2015.01.007
0367-326X/© 2015 Published by Elsevier B.V.
Please cite this article as: Zhong R, et al, Three new labdane-type diterpene glycosides from fruits of Rubus chingii and their
cytotoxic activities against five humor cell li..., Fitoterapia (2015), http://dx.doi.org/10.1016/j.fitote.2015.01.007

2
R. Zhong et al. / Fitoterapia xxx (2015) xxx–xxx
64
65
66
67
68
69
70
performed with silica gel (200–300 mesh, Qingdao Marine
Chemical Ltd., Qingdao, China), Develosil ODS (50 μm, Nomura
Chemical Co. Ltd., Osaka, Japan), and Sephadex LH-20 (GE
Healthcare Bio-Sciences AB, Uppsala, Sweden). TLC (thin layer
chromatography) was carried out with glass precoated with
silica gel GF254. Spots were visualized under UV light or by
spraying with 10% sulfuric acid in EtOH followed by heating.
2.4. Determination of absolute configurations of the sugar moieties 120
in 1−3 121
Based on the reported procedure [10], each (2 mg) of com- 122
pounds 1−3 was dissolved in 2 M HCl (dioxane–H2O, 1:1 v/v) 123
and refluxed for 10 h. After removal of the HCl by evaporation 124
and extraction with EtOAc, the H2O extract was again evaporated 125
and dried in vacuo to furnish a monosaccharide residue. The 126
residue was dissolved in pyridine (1 ml) to which 2 mg L- 127
cysteine methyl ester hydrochloride was added. The mix- 128
ture was kept at 60 °C for 2 h, evaporated under an N2 1Q299
stream, and dried in vacuo, then trimethylsilylated with N- 130
trimethylsilylimidazole (0.2 ml) for 2 h. The mixture was 131
partitioned between n-hexane and H2O (2 ml each), and the 132
n-hexane extract was analyzed by GC. In the acid hydroly- 133
sate of 1−3, D-glucose and D-apiose were verified by 134
comparison with retention times of their derivatives and 135
those of corresponding control samples prepared in the 136
71
2.2. Plant material
72
73
74
75
76
77
The fruits of R. chingii were collected from Jinghua, Zhejiang,
China, in June 2012 and identified by Prof. Cuisheng Fang at
Jiangxi University of Traditional Chinese Medicine, China. A
voucher specimen (no. 20120622) has been deposited in the
Herbarium of Jiangxi Provincial Institute for Drug and Food
Control.
78
2.3. Extraction and isolation
same way.
137
79
The powdered dried fruits of R. chingii (50.5 kg) were
extracted three times with 70% EtOH under reflux (2 h each).
The extracting solution was evaporated under reduced pressure
to yield a dark brown residue (1.1 kg). The residue was
suspended in water (20 L) and then successively partitioned
with petroleum ether (2 × 20 L), EtOAc (3 × 20 L), and n-BuOH
(3 × 20 L). After removing the solvent, the n-BuOH-soluble
portion (175 g) was fractionated via silica gel column chroma-
tography (CC), eluting with CHCl3–MeOH–H2O (17:7:0.5, v/v) to
give twelve fractions (A1–A12). Fraction A10 (4.9 g) was
separated by ODS CC (20–80%, MeOH−H2O) to give seven
fractions (A10–1–A10–7). Fraction A10–3 (1.14 g) was subjected to
macroporous resin CC and eluted with a EtOH–H2O gradient (0%,
20%, 40%, 60%, 80%, v/v). The fractions eluted with 40% EtOH
(180 mg) were further separated by preparative HPLC (YMC-
ODS-A 5 μM, 250 mm × 20 mm, detection at 210 nm) using 55%
MeOH as mobile phase to yield 1 (4 mg), 2 (19 mg), and
3 (5 mg).
2.5. Cytotoxicity assay
138
80
81
Compounds 1−3 were tested for cytotoxicity against HCT-8 139
(human colon cancer cell line), Bel-7402 (human hepatoma 140
cancer cell line), BGC-823 (human gastric cancer cell line), 141
A549 (human lung cancer cell line), and A2780 (human 142
82
83
84
85
ovarian cancer cell line) by MTT assay [11].
143
86
87
3. Results and discussion
144
88
89
The 70% EtOH extract of the fruits of R. chingii was 145
fractionated with petroleum ether, EtOAc and n-BuOH. The n- 146
BuOH-soluble portion was separated by a combination of silica 147
gel, ODS column chromatography and preparative HPLC which 1Q4180
afforded three new compounds (1−3) (Fig. 1). Their structures 1Q4191
were elucidated by extensive NMR techniques mainly includ- 150
ing 1D NMR (1H, 13C NMR), 2D NMR (COSY, NOESY, HSQC and 151
HMBC) (Fig. 2) and ESIMS.
Compound 1 was obtained as a white amorphous powder. 153
The molecular formula, C32H54O13 was determined by 154
90
91
92
93
94
95
96
1Q5122
97
15,18-di-O-β-D-glucopyranosyl-13(E)-ent-labda-7(8),13(14)-
98
diene-3β,15,18-triol (1): white amorphous powder; [α]20
,
D
99
−124 (c 0.1, MeOH); UV (MeOH) λmax (logε): 206 (1.98)
and 255 (1.70) nm; 1H NMR (600 MHz, C5D5N and 13C
NMR (150 MHz, C5D5N see Table 1; positive ESIMS m/z: 669.3
[M + Na]+; negative ESIMS m/z: 645.3 [M−H]−; HRTOFMS m/z
645.3489 [M−H]− (calcd for C32H53O13, 645.3486).
HRTOFMS at m/z 645.3489 [M−H]−, in agreement with the 155
NMR spectroscopic data. The 1H NMR spectrum of 1 in C5D5N 156
showed four methyl singlets at δH 0.81 (3H, s), 1.04 (3H, s), 1.65 157
(3H, s), and 1.69 (3H, s), four oxymethylene protons at δH 3.62 158
and 4.31 (1H each, d, J = 10.2 Hz), δH 4.45 and 4.73 (1H each, d, 159
J = 6.6 Hz), two olefinic protons at δH 5.38 (1H, br s) and 5.63 160
(1H, t, J = 6.6 Hz), and two anomeric protons at δH 4.89 (1H, d, 161
J = 7.8 Hz) and 4.98 (1H, d, J = 7.8 Hz) correlated in the HSQC 162
spectrum with two anomeric carbons at δC 106.0 and 104.4 in 163
the 13C NMR spectrum, respectively (Table 1). The 13C NMR 164
spectrum of 1 displayed 32 carbon signals, of which 12 were 165
assigned to the sugar moieties and the remaining 20 to the 166
aglycone, which was very similar to those of 7,13E-labdadien- 167
3β,15-diol [12]. However, the signal of the methyl group at C- 168
18 of 7,13E-labdadien-3β,15-diol was replaced by a signal of 169
hydroxymethylene group (δC 75.2) in 1. From the foregoing 170
evidences, it was concluded that 1 was a glycoside of labdane- 171
type diterpene. Acid hydrolysis of 1 with 2 M HCl afforded 172
monosaccharides, which were identified as β-D-glucose by GC 173
analysis of their trimethylsilyl L-cysteine derivatives [13] and 174
by the coupling constant of the anomeric proton. In the HMBC 175
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
15,18-di-O-β-D-glucopyranosyl-13(E)-ent-labda-8(9),13(14)-
diene-3β,15,18-triol (2): white amorphous powder; [α]20D −25
(c 0.14, MeOH); UV (MeOH) λmax (logε): 210 (2.05) and 255
(1.86) nm; 1H NMR (600 MHz, C5D5N) and 13C NMR (150 MHz,
C5D5N) see Table 1; positive ESIMS m/z: 669.3 [M + Na]+;
negative ESIMS m/z: 645.3 [M−H]−; HRTOFMS m/z 645.3494
[M−H]− (calcd for C32H53O13, 645.3486).
15-O-β-D-apiofuranosyl-(1 → 2)-β-D-glucopyranosyl-18-O-
β-D-glucopyranosyl-13(E)-ent-labda-8(9),13(14)-di-ene-3β,15,
18-triol (3): white amorphous powder; [α]20 −52 (c 0.09,
D
MeOH); UV (MeOH) λmax (logε): 207 (2.03) and 255 (1.64) nm;
1H NMR (600 MHz, C5D5N) and 13C NMR (150 MHz, C5D5N) see
Table 1; positive ESIMS m/z: 801.4 [M + Na]+; negative ESIMS
m/z: 777.4 [M−H]−; negative ESIMS m/z: 663.3 [M−H]−;
HRTOFMS m/z 777.3955 [M−H]− (calcd for C37H61O17
,
777.3909).
Please cite this article as: Zhong R, et al, Three new labdane-type diterpene glycosides from fruits of Rubus chingii and their
cytotoxic activities against five humor cell li..., Fitoterapia (2015), http://dx.doi.org/10.1016/j.fitote.2015.01.007

R. Zhong et al. / Fitoterapia xxx (2015) xxx–xxx
3
t1:1
t1Q:21 1H and 13C NMR data of compounds 1−3 at 600/150 MHz in pyridine-d5, respectively (δ in ppm, J in Hz).
Table 1
t1:3
Proton
1
2
3
δH
δC
37.7
δH
δC
35.7
δH
δC
35.0
t1:4
1a
1b
2a
2b
3
1.05 (1H, m)
1.76 (1H, m)
1.89 (1H, m)
1.91 (1H, m)
4.23 (1H, m)
1.28 (1H, m)
1.77 (1H, m)
1.96 (1H, m)
2.00 (1H, m)
4.05 (1H, m)
1.22 (1H, m)
1.72 (1H, m)
1.89 (1H, m)
1.94 (1H, m)
4.26 (1H, m)
t1:5
t1:6
28.0
28.6
27.5
t1:7
t1:8
72.9
43.6
42.9
24.4
72.5
43.7
44.5
19.6
71.6
43.0
43.7
18.8
t1:9
4
t1:10
t1:11
t1:12
t1:13
t1:14
t1:15
t1:16
t1:17
t1:18
t1:19
t1:20
t1:21
t1:22
t1:23
t1:24
t1:25
t1:26
t1:27
t1:28
t1:29
t1:30
t1:31
t1:32
t1:33
t1:34
t1:35
t1:36
t1:37
t1:38
t1:39
t1:40
t1:41
t1:42
t1:43
t1:44
t1:45
t1:46
t1:47
t1:48
t1:49
t1:50
t1:51
t1:52
t1:53
5
2.18 (1H, m)
2.10 (1H, m)
1.95 (1H, m)
5.38 (1H, br s)
1.98 (1H, m)
1.79 (1H, m)
1.97 (1H, m)
1.92 (1H, m)
2.36 (1H, m)
1.86 (1H, m)
1.72 (1H, m)
1.80 (1H, m)
1.89 (1H, m)
2.25 (1H, m)
6a
6b
7a
7b
8
123.2
34.2
33.5
135.4
54.9
37.1
26.4
127.0
140.3
39.6
126.3
139.7
38.9
9
1.48 (1H, m)
10
11a
11b
12a
12b
13
14
15a
15b
16
17
18a
18b
19
20
Glc
1′
1.27 (1H, m)
1.53 (1H, m)
1.92 (1H, m)
1.94 (1H, m)
2.03 (1H, m)
2.04 (1H, m)
1.99 (1H, m)
2.15 (1H, m)
27.6
1.92 (1H, m)
26.9
OOF
2.08 (1H, m)
1.96 (1H, m)
1.97 (1H, m)
43.2
40.9
40.2
140.8
122.0
66.6
141.0
121.4
66.6
140.3
120.8
65.9
5.63 (1H, t, 6.6)
4.45 (1H, dd, 12.0, 6.6)
4.73 (1H, dd, 12.0, 6.6)
1.65 (3H, s)
1.69 (3H, s)
3.62 (1H, m)
4.31 (1H, d, 10.2)
1.04 (3H, s)
0.81 (3H, s)
5.66 (1H, t, 6.6)
4.48 (1H, dd, 11.4, 6.6)
4.75 (1H, dd, 11.4, 6.6)
1.68 (3H, s)
5.60 (1H, t, 6.6)
4.40 (1H, dd, 11.4, 6.6)
4.71 (1H, dd, 11.4, 6.6)
1.63 (3H, s)
17.1
22.7
75.2
17.2
20.1
75.1
16.5
19.4
74.0
1.53 (3H, s)
1.44 (3H, s)
3.63 (1H, d, 10.2)
4.50 (1H, d, 10.2)
1.06 (3H, s)
3.58 (1H, d, 10.2)
4.37 (1H, d, 10.2)
0.90 (3H, s)
12.9
14.9
13.7
21.3
12.9
20.6
1.00 (3H, s)
0.97 (3H, s)
4.89 (1H, d, 7.8)
4.26 (1H, m)
4.05 (1H, m)
4.09 (1H, m)
4.27 (1H, m)
4.44 (1H, m)
4.62 (1H, m)
106.0
75.4
79.0
72.3
79.1
63.4
4.89 (d, 7.8)
4.23 (1H, m)
4.02 (1H, m)
4.05 (1H, m)
4.21 (1H, m)
4.38 (1H, dd, 11.4, 5.4)
4.61 (1H, d, 11.4)
106.1
75.5
79.0
72.3
79.2
63.4
4.76 (1H, d, 7.8)
4.15 (1H, m)
4.12 (1H, m)
3.97 (1H, m)
4.00 (1H, m)
4.18 (1H, m)
4.30 (1H, d, 10.2)
105.1
74.6
76.5
72.1
78.3
62.6
2′
3′
4′
5′
6′
Glc
1″
2″
3″
4″
5″
6″
4.97 (1H, d, 7.8)
4.29 (1H, m)
4.01 (1H, m)
4.10 (1H, m)
4.24 (1H, m)
4.34 (1H, m)
4.62 (1H, m)
104.4
75.8
79.1
72.7
79.2
63.6
4.98 (1H, d, 7.8)
4.29 (1H, m)
4.04 (1H, m)
4.11 (1H, m)
4.25 (1H, m)
104.3
75.8
79.1
72.5
79.2
63.5
4.93 (1H, d, 7.8)
3.96 (1H, m)
4.74 (1H, m)
4.15 (1H, m)
3.96 (1H, m)
4.40 (1H, m)
4.53 (1H, d, 11.4)
103.6
75.1
85.9
71.8
78.5
62.7
4.44 (1H, dd, 11.4, 3.6)
4.61 (1H, d, 11.4)
Api
1‴
2‴
3‴
4‴
5‴
5.67 (1H, d, 2.4)
4.73 (1H, m)
4.86 (1H, m)
4.74 (1H, m)
4.09 (1H, m)
110.0
78.3
83.0
74.6
65.9
UNCORRECTED PR
Fig. 1. Chemical structures of compounds 1–3.
Please cite this article as: Zhong R, et al, Three new labdane-type diterpene glycosides from fruits of Rubus chingii and their
cytotoxic activities against five humor cell li..., Fitoterapia (2015), http://dx.doi.org/10.1016/j.fitote.2015.01.007

4
R. Zhong et al. / Fitoterapia xxx (2015) xxx–xxx
Fig. 2. Key HMBC (H → C) correlations of compounds 1–3.
176 spectrum of 1, the two oxymethylene proton signals at δH 3.62
bone. This makes the structures of compounds 1−3 more 219
stable. The aglycone of compounds 1−3 was isolated from 220
Rubus plants for the first time. Compounds 1−3 may be the 221
characteristic metabolites of R. chingii. It may provide evidence 222
177
178
179
180
181
182
183
184
185
186
187
188
189
and 4.31, which correlated with the carbon resonance at δC 75.2
in the HSQC spectrum, showed HMBC correlations with C-3, C-4,
C-5 and C-19, justifying its assignment to C-18. HMBC correla-
tions between the anomeric proton at δH 4.89 (1H, d, J = 7.8 Hz,
H-1′) and the carbon signal at δC 75.2 (C-18) and between H-1″
at δH 4.97 (1H, d, J = 7.8 Hz, H-1′) and C-15 at δC 66.6 indicated
that two β-D-glucopyranosyl units were attached to C-15 and C-
18 positions of the aglycone, respectively. The β-orientation of 3-
OH in 1 was deduced by analysis of the NOESY spectrum which
showed NOE correlations between H-3 and H2-19. Thus, the
structure of 1 was elucidated as 15,18-di-O-β-D-glucopyranosyl-
13(E)-ent-labda-7(8),13(14)-diene-3β,15,18-triol.
for chemical classification of R. chingii.
223
Compounds 1−3 were evaluated for cytotoxic activities 224
against five human cell lines (HCT-8, Bel-7402, BGC-823, A549, 225
and A2780) with paclitaxel as a positive control. Compounds 1 226
and 2 were inactive (IC50 N 10 μM) to HCT-8, Bel-7402, BGC- 227
823, A549, and A2780 cell lines. Compound 3 showed cytotoxic 228
activity only against A549, with an IC50 value of 2.32 μM.
229
Acknowledgments
230
Compound 2 gave the same molecular formula as 1, namely
190 C32H54O13, as deduced by HRTOFMS (m/z 645.3494 [M−H]−
191 calcd for 645.3486) and supported by the NMR spectroscopic
192 data. Comparison of the NMR data of 2 (Table 1) and 1 showed
193 that the two compounds were almost identical except that the
194 7(8)-olefin in 1 is isomerized as 8(9)-olefin in 2. A series
195 of HMBC correlations from H3-17 to C-7, C-8, and C-9, from
196 H3-20 to C-1, C-5, C-9, and C-10 further confirmed the
197 aglycone with a 8(9)-double bone. Thus, compound 2 was
198 determined as 15,18-di-O-β-D-glucopyranosyl-13(E)-ent-
199 labda-8(9),13(14)-diene-3β,15,18-triol.
This study was supported financially by the National Natural 231
Science Foundation of China (NSFC, grant no. 81460589) and 232
Jiangxi province science and technology support program, China 233
(no. 2013BBG0039). We thank Prof. A.H. Liu at Center of Analysis 2Q3145
and Testing Nanchang University for NMR measurements.
235
Appendix A. Supplementary data
236
Supplementary data to this article can be found online at 237
http://dx.doi.org/10.1016/j.fitote.2015.01.007.
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200
201
202
203
204
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207
208
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211
Compound 3 had the molecular formula C37H62O17, as
indicated from the HRTOFMS (m/z 777.3955 [M−H]− calcd for
References
239
777.3909). The NMR spectroscopic data of compound
3
resembled those of 2, except for an additional set of β-D-
apiofuranosyl resonances with an anomeric proton signal at δH
5.67 (1H, d, J = 2.4 Hz) and a downfield shift of C-2 (from δC 79.1
to δC 85.9) of the D-glucopyranosyl unit due to a glycosidation
shift (Table 1). The linkage position of the sugar units with
the aglycone was established from the following HMBC
correlations: H-1′ (δH 4.76) of Glc′ with C-18 (δC 74.0) of
aglycone, H-1″ (δH 4.93) of Glc″ with C-15 (δC 65.9) of aglycone,
and H-1‴ (δH 5.67) of Api with C-3 (δC 85.9) of Glc″. Thus,
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21Q213 compound 3 was identified as 15-O-β-D-apiofuranosyl-(1 → 2)-
213 β-D-glucopyranosyl-18-O-β-D-glucopyranosyl-13(E)-ent-labda-
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2Q1514
Until now, only kaurane- and labdane-type terpenoids were
216 get from R. chingii, and all of labdane-type terpenoids obtained
217 were 8(17) double bone, which could undergo hydrogenation
1996;44:810.
258
218 and dehydrogenation to form 7(8) double bone and 8(9) double
259
Please cite this article as: Zhong R, et al, Three new labdane-type diterpene glycosides from fruits of Rubus chingii and their
cytotoxic activities against five humor cell li..., Fitoterapia (2015), http://dx.doi.org/10.1016/j.fitote.2015.01.007