DOI 10.1007/s10600-017-2240-8
Chemistry of Natural Compounds, Vol. 53, No. 6, November, 2017
CHEMICAL CONSTITUENTS OF Astragalus falcatus
*
M. D. Alaniya, M. G. Sutiashvili,
N. Sh. Kavtaradze, and A. V. Skhirtladze
Previously, we reported on several compounds isolated from the aqueous part of an EtOH–H O extract of leaves and
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flowers of Astragalus falcatus Lam. (Leguminosae) that was left after the EtOH was distilled off and lipophilic substances
were removed by CHCl [1–4]. They were identified as aliphatic alcohol dulcitol; flavonoids astragalin, nicotiflorin, robinin,
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and falcosides A-E; and cycloartanes cyclogalegigenin and its glycosides cyclogaleginosides A and B. The nonpolar fraction
of the extract was examined in detail to study the other constituents.
Herein, the chemical composition of the CHCl extract of the aqueous EtOH extract that was produced by treating
3
leaves and flowers (1 kg) of A. falcatus is reported. The thick residue (180 g) remaining after the CHCl was removed was
3
fractionated over a column of silica gel. The fraction containing several compounds was condensed (2 g) and separated by
repeated rechromatography over a column of the same absorbent. The eluents were CHCl and CHCl –MeOH mixtures with
3
3
increasing concentration of the latter. This produced six compounds 1 (0.1 g), 2 (0.64 g), 3 (0.05 g), 4 (0.06 g), 5 (0.035 g), and
6 (0.053 g). The last was present in significant quantities even in the aqueous part of the purified extract, from which it was
isolated (0.25 g).
The structures of the isolated compounds were elucidated using chemical analyses and UV, IR, and NMR spectra
( H, C, HSQC, COSY, HMBC).
1
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Compound 1, white crystalline powder, mp 290°C, MM 576.86 (mass spectrometry), C H O . IR spectrum (KBr,
35 60
6
–1
1
ꢀ
, cm ): 3425 (OH), 2960 (CH ), 1460, 1075, 1020 (ÑÍ-ÑÍ). Í NMR spectrum (600 MHz, CD OD, ꢁ, ppm, J/Hz):
max
3
3
0.74 (3Í, s, CH -18), 0.84 (3H, d, J = 6.8, CÍ -27), 0.87 (3H, d, J = 5.5, CÍ -26), 0.88 (3H, t, J = 7.4, CÍ -29), 0.95 (3Í, d,
3
3
3
3
J = 5.1, CÍ -21), 0.93 (1Í, m, Í-24), 0.96 (1Í, m, Í-9), 1.02 (1H, m, Í -11), 1.03 (1H, m, Í-14), 1.05 (3H, s, CÍ -19), 1.09
3
a
3
(1H, m, Í -1), 1.12 (1H, m, Í -15), 1.14 (1H, m, Í-17), 1.19 (1H, m, Í -12), 1.22 (2Í, m, H-23), 1.28 (2H, m, Í-28), 1.33 (1H,
a
a
a
m, Í -16), 1.32 (1H, m, Í -22), 1.40 (1H, m, Í-20), 1.45 (2H, m, Í -11), 1.48 (1H, m, Í-8), 1.55 (1H, m, Í -7), 1.55 (1H, m,
a
a
b
a
Í -22), 1.61 (1H, m, Í -15), 1.63 (1H, m, Í -2), 1.69 (1H, m, Í-25), 1.88 (1H, m, Í -16), 1.89 (1H, m, Í -1), 1.93 (1H, m,
b
b
a
b
b
Í -2), 1.99 (1H, m, Í -7), 2.05 (1H, m, Í -12), 2.27 (1H, br.t, J = 10.0, Í -4), 2.43 (1H, m, Í -4), 3.16 (1H, dd, J = 7.8, 9.0,
b
b
b
a
b
Í-2ꢂ), 3.27 (1H, m, Í-5ꢂ), 3.28 (1H, m, Í-4ꢂ), 3.36 (1H, dd, J = 9.0, 9.0, Í-3ꢂ), 3.59 (1H, m, Í-3), 3.66 (1H, dd, J = 4.7, 12.0,
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Í -6ꢂ), 3.90 (1H, dd, J = 1.7, 12.0, Í -6ꢂ), 4.39 (1H, d, J = 7.8, Í-1ꢂ), 5.38 (1H, d, J = 5.0, Í-6). C NMR spectrum
a
b
(150 MHz, CD OD, ꢁ, ppm): 38.2 (Ñ-1), 30.4 (Ñ-2), 79.7 (Ñ-3), 39.4 (Ñ-4), 141.8 (Ñ-5), 122.5 (Ñ-6), 32.7 (Ñ-7), 33.0 (Ñ-8),
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51.4 (Ñ-9), 37.6 (Ñ-10), 21.8 (Ñ-11), 40.8 (Ñ-12), 43.4 (Ñ-13), 57.8 (Ñ-14), 25.3 (Ñ-15), 29.0 (Ñ-16), 57.1 (Ñ-17), 12.0
(Ñ-18), 19.7 (Ñ-19), 37.1 (Ñ-20), 19.1 (Ñ-21), 32.8 (Ñ-22), 27.0 (Ñ-23), 47.1 (Ñ-24), 30.0 (Ñ-25), 19.6 (Ñ-26), 19.6 (Ñ-27),
23.9 (Ñ-28), 12.0 (Ñ-29), 102.1 (Ñ-1ꢂ), 74.8 (Ñ-2ꢂ), 77.9 (Ñ-3ꢂ), 71.4 (Ñ-4ꢂ), 77.7 (Ñ-5ꢂ), 62.7 (Ñ-6ꢂ).
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C NMR and PMR spectra showed resonances at ꢁ 141.8, 122.5, and 5.38, respectively, indicating that the tetracyclic
part of the molecule contained a double bond. The PMR spectrum showed resonances at ꢁ 0.74–1.05 for six methyl groups,
one of which (ꢁ 0.88) was coupled to a CH group [ꢁ 1.28 (2H) and 23.9] of the C-24 side chain. Achemical shift of ꢁ 79.7 was
2
consistent with a substituent on the genin C-3. Compound 1 was a glycoside according to resonances for an anomeric proton
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and D-glucose C-1ꢂ at ꢁ 4.39 and 102.1 in the PMR and C NMR spectra, respectively. The compound was hydrolyzed by
H SO solution (5%) to give D-glucose and the genin with mp 132–133°C that was identical to ꢃ-sitosterol [5]. The analytical
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4
data and a comparison with literature data identified 1 as daucosterol or 3-O-ꢃ-D-glucopyranosyl-ꢃ-sitosterol [6].
I. G. Kutateladze Institute of Pharmacochemistry, Tbilisi State Medical University, 36 P. Sarajishvili St., Tbilisi,
0159, Georgia, e-mail: merialania@yahoo.com. Translated from Khimiya Prirodnykh Soedinenii, No. 6, November–December,
2017, pp. 1018–1019. Original article submitted January 24, 2017.
©
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0009-3130/17/5306-1202 2017 Springer Science+Business Media New York