Structure of cyclochivinoside C from Astragalus chivensis

Article abstract of DOI:10.1007/s10600-007-0192-0

The new cycloartane glycoside cyclochivinoside C, 24S-cycloartan-3β, 6α,16β,24,25-pentaol 3,16-di-O-β-D-glucopyranoside, was isolated from the aerial part of Astragalus chivensis. The structures of the isolated compounds were established by chemical transformations and PMR and ¹³C NMR spectra.

Full text of DOI:10.1007/s10600-007-0192-0

Chemistry of Natural Compounds, Vol. 43, No. 5, 2007
STRUCTURE OF CYCLOCHIVINOSIDE C
FROM Astragalus chivensis
UDC 547.918:547.926
T. Kh. Naubeev and K. K. Uteniyazov
S
O
The newcycloartaneglycoside cyclochivinoside C, 24 -cycloartan-3β,6α,16β,24,25-pentaol 3,16-di- -β-D-
Astragalus chivensis.
glucopyranoside, was isolated from the aerial part of
The structures of the isolated
13
compounds were established by chemical transformations and PMR and C NMR spectra.
cycloartanes, cyclocanthogenin, cyclochivinoside C, cyclosiversioside E, cyclosiversigenin.
Key words:
In continuation of research on cycloartane triterpenoids from plants of the genus
[1], we isolated from the
Astragalus
butanol extract of
Bunge (Leguminosae) cyclosiversioside E ( ) [2, 3] and a newglycosidiccompoundthat wecalled
A. chivensis
1
cyclochivinoside C ( ).
2
The PMR spectrum of contained in the strong-field region resonances for protons ofseven methyls at 1.42, 1.40, 1.61,
1
13
1.40, 1.11, 1.89, and 1.40 ppm and for two anomeric protons at 4.83 and 4.81 ppm. The C NMR spectrum of had
1
resonances for two anomeric C atoms at 107.7 and 105.8 ppm.
These data indicated that was a bioside.
1
13
The structure of was confirmed conclusively using PMR and C NMR and two-dimensional spectra. They agreed
1
with those reported for cyclosiversioside E [2, 3].
The presence in the PMR spectrum of glycoside (Table 1) of 1H doublets at 0.22 and 0.54 ppm for an AB system
2
typical of a 1,1,2,2-tetrasubstituted three-membered ring and resonances for seven methyls at high field indicated that this
compound was a cycloartane triterpenoid.
13
The C atoms in the cyclopropane ring, C-9, C-10, and C-19, resonated in the C NMR spectrum of at 21.24, 29.37,
2
and 29.60 ppm, respectively. This confirmed the conclusion that this compound was a cyclartane.
Acid hydrolysis of produced the genin, which was identified as cyclocanthogenin ( ) [4]. TLC and paper
2
3
chromatography of the carbohydrate part of the hydrolysate detected glucose.
OH
OH
26
21
18
23
25
27
OH
OH
O
OH
19
17
13
+
11
7
H
D Glcp
β
15
1
9
3
5
28
D Glcp
O
β
HO
OH
OH
29
2
3
13
The PMR and C NMR spectra of showed clearly resonances for two anomeric protons at 4.98 and 5.02 ppm and
2
for two anomeric C atoms at 106.91 and 106.71 ppm, respectively.
Judging from these data, the new compound was a bioside.
13
A low-field shift in the C NMR spectrum of the resonances for C-3 and C-16 in compared with those in
2
cyclocanthogenin ( ) determined the sites of attachment of the sugars.
3
S. Yu. Yunusov Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan,
Tashkent, fax (99871) 120 64 75, e-mail: ukarim@inbox.ru. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 460-
462, September-October, 2007. Original article submitted January 16, 2007.
0009-3130/07/4305-0560 ©2007 Springer Science+Business Media, Inc.
560

TABLE 1. PMR and 13C NMR Spectra of Cyclochivinoside C (2) and Cyclocanthogenin (3) (C5D5N, δ, ppm, TMS = 0)
Cyclochivinoside C
Cyclocanthogenin [4]
13C
Cyclochivinoside C
Cyclocanthogenin [4]
13C
C atom
C atom
1H
13C
1H
13C
1
2
1.57; 1.16
2.48; 1.95
3.67
32.53
30.18
88.92
42.71
54.11
68.15
38.42
46.36
21.24
29.37
26.28
33.19
45.75
46.12
47.53
82.15
57.35
18.26
29.60
31.11
18.93
33.95
32.54
31.17
78.10
42.18
53.73
68.04
38.33
46.94
21.02
29.71
26.17
32.95
45.47
46.67
48.16
71.75
57.11
18.03
29.09
28.44
18.77
32.81
23
24
25
26
27
28
29
30
2.10; 1.68
3.91
-
29.78
77.21
72.56
25.70
26.54
20.23
28.55
16.43
27.67
76.99
72.88
25.48
26.07
19.93
29.34
15.87
3
4
-
1.49
1.47
1.04
1.99
1.35
5
1.75
6
3.76
7
1.83; 1.64
1.94
8
9
-
3-O-β-D-Glcp
106.91
75.82
10
11
12
13
14
15
16
17
18
19
20
21
22
-
1
2
3
4
5
6
5.02
4.07
1.89; 1.24
1.68
4.24
78.67
-
4.24
71.72
-
3.95
78.06
2.15; 1.74
4.38
4.56; 4.39
63.10
16-O-β-D-Glcp
106.71
1.85
1
2
3
4
5
6
4.98
4.02
1.37
75.63
0.54; 0.22
2.37
4.29
78.24
71.65
77.98
62.87
4.22
1.12
3.88
2.28; 1.43
4.54; 4.36
13
A comparison of the C NMR spectra of cyclochivinoside C and cyclocanthogenin showed that C atoms C-3 and C-16
experienced glycosylation effects in the spectrum of the former. They resonated at 88.92 and 82.15 ppm, respectively.
13
The configuration of the asymmetric center at C-24 of 2 was determined by comparing C NMR spectra of 2 and
13
cyclounifolioside C [4]. The resonance for this C atom in the C NMR spectrum of cyclounifolioside C, which has the
C-(24 )-configuration, occurred at 80.29 ppm whereas in the spectrum of 2 this resonance shifted to strong field by
R
3.08 ppm (77.21 ppm).
13
Thedifferencein thechemical shifts for C-24 atoms in C NMRspectra ofdammaranetriterpeneglycosidesbelonging
to the 24( ) and 24( ) series was 2.7-3.3 ppm with C-24 in the -configuration resonating at stronger field [5]. Based on these
R
S
S
results, we thought that C-24 in 2 had the -configuration and the hydroxyl was situated in the α-orientation.
S
Based on these data, it can be concluded that 2 is 24 -cycloartan-3β,6α,16β,24,25-pentaol 3,16-di- -β-D-
S
O
glucopyranoside.
EXPERIMENTAL
General comments have been published [1].
Separation of the Butanol Fraction. Column chromatography of the butanol fraction using CHCl :CH OH:H O
3
3
2
(4:1:0.1) isolated 2 (23 mg, 0.0011% based on air-dried raw material).
Cyclosiversioside E (1). C H O , mp 252-254°C (MeOH).
40 66 13
PMR spectrum (C D N, δ, ppm): 1.59, 1.27 (H-1), 2.34, 1.97 (H-2), 3.45 (H-3), 1.87 (H-5), 3.70 (H-6), 2.13, 2.00
5
5
(H-7), 2.08 (H-8), 1.75, 1.52 (H-11), 1.69, 1.53 (H-12), 2.31, 1.80 (H-15), 5.05 (H-16), 2.58 (H-17), 1.42 (H-18), 0.15, 0.60
(H-19), 1.40 (H-21), 3.11, 1.68 (H-22), 2.28, 2.04 (H-23), 3.89 (H-24), 1.61 (H-26), 1.40 (H-27), 1.11 (H-28), 1.89 (H-29), 1.40
(H-30); β-D-Xyl ′: 4.83 (H-1), 4.07 (H-2), 4.13 (H-3), 4.22 (H-4), 4.35, 3.68 (H-5); β-D-Xyl ′′: 4.81 (H1), 4.00 (H-2), 4.16
p
p
(H-3), 4.17 (H-4), 4.32, 3.65 (H-5).
561

13
C NMR spectrum (C D N, δ, ppm): 32.0 (C-1), 30.1(C-2), 88.4(C-3), 42.7 (C-4), 52.2 (C-5), 77.9 (C-6), 33.7 (C-7),
5
5
44.3 (C-8), 20.8 (C-9), 28.4 (C-10), 26.4 (C-11), 33.6 (C-12), 45.3 (C-13), 46.3 (C-14), 46.0 (C-15), 73.5 (C-16), 58.2 (C-17),
20.6 (C-18), 26.9 (C-19), 87.4 (C-20), 28.7 (C-21), 35.0(C-22), 26.5 (C-23), 81.8 (C-24), 71.3 (C-25), 28.2 (C-26), 27.2 (C-27),
19.8 (C-28), 28.2(C-29), 16.7 (C-30); β-D-Xylp″: 107.7 (C-1), 75.7 (C-2), 78.6 (C-3), 71.3 (C-4), 67.1 (C-5); β-D-Xylp′′: 105.8
(C-1), 75.4 (C-2), 78.6 (C-3), 71.2 (C-4), 67.0 (C-5).
20
Literature data for 1 [2]: mp 218-220°C (MeOH), [α]
+29.9° (c 0.67, MeOH).
D
Acid Hydrolysis. Glycoside 1 (30 mg) was hydrolyzed by methanolic H SO (10 mL, 0.5%) at boiling for 6 h. The
2
4
mixture was diluted with water. The methanol was distilled. The hydrolysate was cooled and extracted with CHCl . The
3
CHCl extract was washed with water and evaporated to dryness in a rotary evaporator. The solid was chromatographed over
3
a silica-gel column with elution by CHCl :CH OH (25:1) to afford cyclosiversigenin (4, 13 mg), C H O , mp 240-
3
3
30 50 5
242°C (MeOH). The hydrolysate was neutralized with BaCO and evaporated. Paper chromatography (PC) using
3
n-butanol:pyridine:water (6:4:3) detected xylose by comparison with an authentic sample.
20
Literature data for 4 [6]: mp 239-241°C (ethylacetate), [α]
+44.0 ± 2° (c 1.58, MeOH).
D
Cyclochivinoside C (2), C H O , mp 258-260°C (MeOH).
42 72 15
13
Table 1 gives the PMR and C NMR spectra.
Acid Hydrolysis. Glycoside 2 (15 mg) was hydrolyzed as described above. The column was eluted by CHCl :CH OH
3
3
(25:1) to afford 3 (5 mg). The hydrolysate was neutralized with BaCO and evaporated. PC using n-butanol:pyridine:water
3
(6:4:3) detected glucose by comparison with an authentic sample.
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1.
2.
3.
4.
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K. K. Uteniyazov, Z. Saatov, M. G. Levkovich, and N. Zh. Abdullaev, Khim. Prir. Soedin., 509 (1998).
K. J. Kucherbaev, K. K. Uteniyazov, V. V. Kachala, Z. Saatov, and A. S. Shashkov, Khim. Prir. Soedin., 364
(2002).
5.
6.
O. Tanaka and S. Yahara, Phytochemistry, 17, 1353 (1978).
A. N. Svechnikova, R. U. Umarova, M. B. Gorovits, and N. K. Abubakirov, Khim. Prir. Soedin., 67 (1981).
562