Furostanol glycosides from leaves of the chinese plant tribulus terrestris

Article abstract of DOI:10.1007/s10600-010-9578-5

The structures of five furostanol glycosides (1-5), of which the 26-O-β-D-glucopyranosyl-(25S),5α-furost-20(22)-en-12-one-2α, 3β,26-triol-3-O-β-D-glucopyranosyl-(1→4)-β-D- galactopyranoside (1) was new, from the leaves of Tribulus terrestris L. were estab

Full text of DOI:10.1007/s10600-010-9578-5

Chemistry of Natural Compounds, Vol. 46, No. 2, 2010
FUROSTANOL GLYCOSIDES FROM LEAVES
OF THE CHINESE PLANT Tribulus terrestris
1,2
2*
1
1
Yajuan Xu, Tunhai Xu, Yue Liu, Shengxu Xie,
UDC 547.918
1
2
1
Yunshan Si, Tonghua Liu, and Dongming Xu
The structures of five furostanol glycosides (1–5), of which the 26-O-ꢀ-D-glucopyranosyl-(25S),5ꢁ-furost-
20(22)-en-12-one-2ꢁ,3ꢀ,26-triol-3-O-ꢀ-D-glucopyranosyl-(1ꢂ4)-ꢀ-D-galactopyranoside (1) was new, from
the leaves of Tribulus terrestris L. were established using chemical and NMR spectroscopic methods.
Keywords: Tribulus terrestris L., Zygophyllaceae, furostanol glycosides.
Tribulus terrestris L. is an annual creeping herb widespread in China. It is also distributed in Japan, Korea, the
western part of Asia, the southern part of Europe, and Africa. In traditional Chinese medicine, the fruit of T. terrestris is used
for treating eye problems, edema, abdominal distention, high blood pressure, and cardiovascular diseases [1]. In the previous
studies, several steroidal saponins and flavonoid constituents were isolated from the fruit and leaf of this plant [2–5]. Later,
much more attention was paid to studies of the chemical components of T. terrestris, and more than 30 steroidal saponins have
been isolated from this plant [6–9]. Recently, the crude saponin fraction of the leaves of this plant has been used as a cordial
drug. In this paper, we report the structure of the five furostanol glycosides from the dried leaves of this plant.
Compounds 2–5 were identified as 26-O-ꢀ-D-glucopyranosyl-(25R),5ꢁ-furost-20(22)-en-12-one-3ꢀ,26-diol-3-O-ꢀ-
D-galactopyranosyl(1ꢂ2)-ꢀ-D-glucopyranosyl-(1ꢂ4)-ꢀ-D-galactopyranoside (2) [6], 26-O-ꢀ-D-glucopyranosyl-(25R,S),5ꢁ-
furost-20(22)-en-12-one-3ꢀ,26-diol-3-O-ꢀ-D-glucopyranosyl(1ꢂ4)-ꢀ-D-galactopyranoside (3) [7], 26-O-ꢀ-D-glucopyranosyl-
(25R),5ꢁ-furost-12-one-3ꢀ,22ꢁꢃ26-triol-3-O-ꢀ-D-glucopyranosyl-(1ꢂ2)-ꢀ-D-galactopyranoside (4) [7], and 26-O-ꢀ-D-
glucopyranosyl-(25R),5ꢁ-furost-22-methoxy-3ꢀ,26-diol-3-O-[ꢀ-xylopyranosyl(1ꢂ2)-[ꢀ-xylopyranosyl(1ꢂ3)]-ꢀ-D-
glucopyranosyl-(1ꢂ4)-[ꢁ-rhamnopyranosyl(1ꢂ2)]-ꢀ-D-galactopyranoside (5) [8], respectively, which were isolated from
13
the fruits of Tribulus terrestris L. Compounds 2–5 were identified by comparison of the ESI-MS, C NMR, melting point
(mp), and optical rotation data ([ꢁ] ) with reference data. They were all isolated for the first time from the leaves of Tribulus
D
terrestris L.
OH
HO
HO
O
O
HO
H
H C
3
CH
3
O
CH
H
3
O
CH
3
H
HO
H
OH
O
OH
O
O
H
O
HO
HO
HO
HO
H
1
HO
H
Fig. 1. Key HMBC correlations (HꢂC) Compound 1.
1) Institute of Traditional Chinese Medicine, Jilin Academy of Chinese Medicine Sciences, Changchun, 130021,
P. R. China; 2) Department of Traditional Chinese Medicine Chemistry, School of Traditional Chinese Medicine, Beijing
University of Chinese Medicine, Beijing 100102, P. R. China, fax: 86 01 64286162, e-mail: thxu@yahoo.com. Published in
Khimiya Prirodnykh Soedinenii, No. 2, pp. 201–204, March–April, 2010. Original article submitted December 1, 2008.
242
0009-3130/10/4602-0242 02010 Springer Science+Business Media, Inc.

13
TABLE 1. Chemical Shifts for C Atoms of Aglycons of Compounds 1–5 and Protons of the Aglycon of Compound 1
(C D N, 0 = TMS,ꢅꢄ, ppm, J/Hz)
5
5
1
2
3
4
5
C atom
ꢄC
ꢄH
ꢄC
1
2
3
4
5
6
7
8
45.34
70.32
84.50
33.94
44.60
27.96
31.47
33.99
55.58
37.42
38.44
212.75
57.71
54.16
33.85
83.13
56.38
14.32
13.00
103.57
11.77
153.30
23.85
31.56
33.63
75.09
17.45
36.84
29.91
78.17
34.80
44.63
28.74
31.99
34.23
59.69
36.46
38.33
213.02
57.70
54.31
33.85
83.32
56.37
14.31
11.88
103.28
11.77
153.30
23.83
31.45
33.93
75.26
17.25
38.14
29.99
78.17
36.08
46.63
29.74
32.29
35.23
57.69
37.46
39.33
214.32
58.70
56.11
34.85
84.32
56.37
14.81
12.28
104.28
11.77
154.30
24.23
33.33
34.29
75.95
17.80
36.65
29.68
78.53
34.37
44.59
27.94
31.80
34.37
55.78
36.91
37.60
213.02
55.60
55.78
32.03
80.20
55.09
16.39
11.64
41.06
15.36
110.88
37.23
28.50
34.37
75.19
17.45
37.30
29.82
77.10
34.13
44.56
28.87
32.23
34.96
54.93
36.11
21.12
39.91
41.14
56.23
32.01
81.30
64.27
16.35
12.38
40.46
16.10
112.50
30.71
28.09
34.15
75.06
17.08
3.80
3.69
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
4.62
3.29
0.80
0.63
1.61
3.48, 4.06
0.90 (J = 6.2)
Compound 1, obtained as a white powder, showed a red coloration with Ehrlich reagent. The IR spectrum showed
–1
–1
–1
absorptions for hydroxyl groups (3420 cm ), carbonyl group (1702 cm ), and double bond (1624 cm ). Compound 1
exhibited the molecular formula C H O by its HR-MS spectrum. The ESI-MS of 1 showed a negative ion peak at m/z 931
45 72 20
–
–
–
–
[M – H] , and significant ion peaks at m/z: 769 [M – H – 62] , 607 [M – H – 162 – 162] , 445 [M – H – 162 – 162 – 162] ,
corresponding to the loss of three hexosyl moieties. Calculated from the ESI-MS, the molecular weight of the aglycone moiety
was 444, 14 more than that of tribufuroside B [9]. In comparison to tribufuroside B, there was one more quaternary carbon and
13
one less secondary carbon in the C NMR spectrum by DEPT measurements, and there were absorptions for carbonyl group
13
in the IR spectrum. The C NMR data of the aglycone of 1 (Table 1) were almost consistent with those of the aglycone of
tribufuroside B, except that, owing to the carbonyl group in C-12, the signals of C-11 (ꢄ 38.44) and C-13 (ꢄ 57.71) shifted
downfield compared with those of tribufuroside B, which showed that the structural difference between the aglycone of 1 and
that of tribufuroside B was the carbonyl group at C-12 in the aglycone moiety of 1. Thus, the aglycone moiety of 1 was
deduced to be 5ꢁ-furost-20(22)-en-12-one-2ꢁ,3ꢀ,26-triol. The 25S configuration of 1 was confirmed by comparison of the
1
26-methylene signals for 1 with those for trigoneoside Xa [10] and trigoneoside Ia [11] in the H NMR specrum. The proton
1
signals assignable to the 26-methylene group [ꢄ 3.48 (1H, dd, J = 7.5, 9.5 Hz, H -26), 4.06 (1H, m, H -26)] in the H NMR
a
b
specrum of 1 were very similar to those of trigoneoside Ia and trigoneoside Xa [10, 11].
Acid hydrolysis of 1 with mineral acid afforded galactose and glucose as the sugar components, identified on TLC by
comparison with authentic samples. The coupling constants of the anomeric signals revealed the ꢀ-configuration for glucose
and galactose [12, 13].
243

13
TABLE 2. Chemical Shifts for CAtoms of Carbohydrates of Glycosides 1–5 and Protons of the Carbohydrates of Glycoside
1 (C D N, 0=TMS, ꢄ, ppm, J/Hz)
5
5
1
2
3
4
5
C atom
ꢄC
ꢄH
ꢄC
C3-O
Gal
103.32
73.19
75.33
80.29
76.07
61.07
Glc
107.28
75.93
78.86
72.38
78.64
63.24
Gal
Gal
102.54
73.56
76.02
80.85
75.45
60.61
Glc
105.22
85.24
77.98
72.07
78.40
63.30
Gal
107.10
74.72
74.19
71.02
77.70
63.00
Gal
103.54
73.45
75.98
79.45
76.15
61.61
Glc
106.62
75.64
78.48
72.32
78.55
63.45
Gal
103.57
73.19
75.46
80.29
76.07
61.02
Glc
107.30
75.91
78.86
72.37
78.62
63.22
Gal
100.07
76.55
76.59
81.20
75.61
60.35
Glc
105.10
81.26
87.60
70.25
77.59
62.67
Xyl
105.26
74.95
78.60
70.82
67.52
1
2
3
4
5
6
4.80 (d, J = 7.5)
4.39
4.28
4.55
4.09
4.26, 4.62
Glc
5.14 (d, J = 7.5)
4.10
Xyl
105.66
74.88
78.97
70.86
67.35
1
2
3
4
5
6
4.32
4.22
4.01
4.64, 4.43
Rha
101.92
72.21
72.66
73.87
69.31
18.43
1
2
3
4
5
6
C26-O
Glc -1
105.04
75.33
78.75
71.89
78.64
63.01
Glc -1
4.71 (d, J = 7.5)
4.07
Glc -1
105.30
75.43
79.04
71.90
78.90
61.78
Glc -1
105.10
75.63
78.74
71.78
78.60
63.20
Glc -1
105.25
75.35
78.62
71.84
78.74
62.95
Glc -1
104.89
75.25
78.43
71.56
78.58
62.78
1
2
3
4
5
6
4.20
4.77
3.99
4.56, 4.35
The positions of the sugar residues in 1 were defined unambiguously by HMBC experiments (Fig. 1). The cross-peaks
due to long-range correlations between Gal H-1 (ꢄ 4.80) of galactose and C-3 (ꢄ 84.50) of the aglycone, and between Glc
H-1 (ꢄ 5.14) of glucose and C-4 (ꢄ 80.29) of galactose indicated that the disaccharide moiety, 3-O-ꢀ-D-glucopyranosyl-
(1ꢂ4)-ꢀ-D-galactopyranoside, was linked to the aglycone at C-3. Additionally, the cross-peaks between H-1 (ꢄ 4.71) of
glucose and C-26 (ꢄ 75.09) of the aglycone showed that the glucose was linked to C-26 of the aglycone. On the basis of all of
this, 1 was identified as 26-O-ꢀ-D-glucopyranosyl-(25S),5ꢁ-furost-20(22)-en-12-one-2ꢁ,3ꢀ,26-triol-3-O-ꢀ-D-glucopyranosyl-
(1ꢂ4)-ꢀ-D-galactopyranoside.
EXPERIMENTAL
1
13
General Methods. H NMR and C NMR, HMQC, and HMBC spectra: Bruker AM-500 instrument; ESI-MS:
LCQ-1700 ESI-MS instrument; IR spectra: Y-Zoom scroll Fourier transform infrared spectrometer; WZZ-15 optical rotation
apparatus.
Plant Material. The fruits of Tribulus terrestris L. were purchased from the Chinese Medicinal Materials Company
in Changchun, Jilin Province, China, in September 2002, and identified by Professor Minglu Deng, Changchun College of
Traditional Chinese Medicine. Avoucher specimen (020925) has been deposited in the Herbarium of theAcademy of Traditional
Chinese Medicine and Materia Medica of Jilin Province.
244

Extraction and Purification. The dried fruits (5 kg) were exhaustively extracted with 60% EtOH, and the extract
was concentrated under reduced pressure to obtain a crude residue (166 g), which was chromatographed over a D macroporous
101
resin column (10 ꢆ 80 cm) and eluted successively with H O, 30% EtOH, and 70% EtOH. The 70% EtOH eluate was concentrated
2
to dryness (15 g saponin mixture) and chromatographed over a silica gel column (200–300 mesh) eluted with CHCl –MeOH–
3
H O 30:10:1ꢂ10:10:1 to give fractions 1–4. Fraction 2 was subjected to HPLC (column: 10 ꢆ 250 mm, RP-18, 10 ꢇm, flow
2
rate: 3.0 mL/min) with MeOH–H O (65:35) as mobile phase to afford 1 (45 mg), 3 (29 mg), and 4 (23 mg). Fraction 4 was
2
subjected to HPLC eluting with MeOH–H O (60:40) to afford 2 (38 mg), 5 (26 mg).
2
Acid Hydrolysis of Compound 1. The saponin (10 mg) was heated with 2M HCl–MeOH (10 mL) under reflux for
3 h. The reaction mixture was diluted with H O and extracted with CHCl . The water layer was neutralized with Na CO ,
2
3
2
3
concentrated, and subjected to TLC analysis with authentic samples of D-glucose and L-galactose, and developed with
CH Cl –MeOH–H O (15:6:1). Detection was carried out with aniline phthalate spray.
2
2
2
25
Compound 1, C H O , white amorphous powder, mp 212ꢈC (dec.),
+4.6ꢈ (c 1.25; pyridine); HR-FAB-MS
[ꢁ]D
45 72 22
–
–1
m/z: 931.46276 (calcd for C H O , 931.46169); ESI-MS: 931 [M – H] ; IR (KBr, ꢉ , cm ): 3420 (OH), 1702 (C=O),
1624 (C=C). H NMR and C NMR, as well as HMBC and HMQC; for spectral data, see Tables 1 and 2 and Fig. 1.
45 72 22
max
1
13
25
Compound 2, C H O , white amorphous powder, mp 202ꢈC (dec.),
+2.6ꢈ (c 1.25; pyridine), ESI-MS m/z:
+6.0ꢈ (c 0.3; pyridine), ESI-MS m/z:
–18.4ꢈ (c 0.50; pyridine), ESI-MS
[ꢁ]D
51 82 24
–
13
1077 [M – H] ; for C NMR, see Tables 1 and 2.
20
Compound 3, C H O , white amorphous powder, mp 205ꢈC (dec.),
[ꢁ]D
45 72 19
–
13
915 [M – H] ; for C NMR, see Tables 1 and 2.
[ꢁ]2D0
Compound 4, C H O white amorphous powder, mp 228ꢈC (dec.),
45 74 20,
–
13
m/z: 935 [M – H] ; for C NMR, see Tables 1 and 2.
20
Compound 5, C H O , white amorphous powder, mp 216ꢈC (dec.),
–69ꢈ (c 0.50; MeOH), ESI-MS m/z:
[ꢁ]D
62 104 31
13
1369 [M + Na]+; for C NMR, see Tables 1 and 2.
ACKNOWLEDGMENT
The authors are grateful to the Program for New Century Excellent Talents in University (NCET-08-0746) and
Cooperation Program of the Beijing Municipal Education Commission, and the National Natural Science Foundation of China
(No. 30873357).
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