Chemistry of Natural Compounds, Vol. 44, No. 6, 2008
COUMARINS FROM Astragalus asper
N. N. Guzhva
UDC 582.736:547.814.06
Wecontinuedresearch on coumarinsfrom the aerial part ofAstragalus asper. The CHCl fraction obtainedbyselective
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extraction of the total extract from A. asper Jacq. growing in the Caucasus foothills on Stavropol plateau [1] were placed on a
silica-gel column (1:10ratio) and eluted successivelywith hexane, hexane:CHCl with increasingCHCl content, anda gradient
3
3
of CHCl :CH OH (9:1-6:4) [2].
3
3
Compounds 1-4 were obtained by elution with a gradient of hexane:CHCl (4:6-2:8). Qualitative reactions, PC, and
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TLC identified the isolated compounds as α-pyrone-coumarin derivatives [2, 3]. Spots of 1 and 2 on the chromatograms gave
blue fluorescence that intensified upon treatment with ethanolic KOH or ammonia vapor. This was consistent with a C7
hydroxyl in the coumarin ring [3].
Thestructuresoftheisolatedcompoundswereestablishedbycomparison with standardsandphysicochemical constants
from UV and IR spectroscopy using ionizing and complexing additives [SF-46 (USSR), UR-20 (Germany)]. Chromatography
used BuOH:CH CO H:H O (1, 4:1:8) and CHCl (2) (paper impregnated with formamide:acetone, 1:3).
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2
2
3
Compound 1, C H O , white needle-like crystals, mp 231-233°C (MeOH), R 0.33 (system 1), 0.88 (system 2).
9
6
3
f
UV spectrum (EtOH, λmax, nm): 256, 325. Addition of sodium acetate produced a bathochromic shift of the long-wavelength
−
1
band (240, 378 nm). IR spectrum (KBr, ν, cm ): 1616-1575 (–C=C–), 3300 (–OH), 1718 (>C=O). Based on these results and
the lack of melting-point depression of a mixed sample with a standard, 1 was characterized as 7-hydroxy-coumarin,
umbelliferone [2, 3].
Compound 2, C H O , white crystalline powder with a cream tint, mp 204-206°C (MeOH), R 0.56 (system 1), 0.38
1
0
8
4
f
(
system 2). UV spectrum (λmax, nm): 256, 300, 315, 340. Addition of sodium acetate produced a bathochromic shift ofthe long-
−
1
wavelength band (240, 378 nm). IR spectrum (cm ): 1708 (>C=O), 3300-3350 (–OH), 2930, 2845 (–OCH ).
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Based on these results and comparison with a standard sample, 2 was characterized as 7-hydroxy-6-methoxycoumarin,
scopoletin [3].
Compound 3, white needle-like crystals, mp 215-219°C (MeOH), soluble in water, methanol, ethanol. UV light
produced a bright blue fluorescence that intensified after treatment with base. UV spectrum (EtOH, λmax, nm): 250, 315. Acid
hydrolysis formed an aglycon with mp 230-231°C that had the same mobility on paper chromatographyas an authentic sample
of umbelliferone. It was very soluble in ethanol, acetone, and diethylether and insoluble in water. UV spectrum (EtOH,
λ
max, nm): 255, 324. The IR spectrum of the aglycon was completelyidentical to that of umbelliferone. Paper chromatography
(
n-BuOH:H O:Py, 6:4:3) of the carbohydrate part of the acid hydrolysate detected glucose upon detection by anilinium acid
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phthalate (100-105°C). Comparing our resultswith theliteratureledtotheconclusion that3wasumbelliferone 7-O-β-glucoside
or skimmin [2].
Compound4, whitethin prismatic crystals, mp 212-215°C (MeOH), soluble in water, methanol, and ethanol. UVlight
produced bright blue fluorescence. UV spectrum (EtOH, λmax, nm): 285, 310. Acid hydrolysis isolated an aglycon as white
needle-likecrystals, paper chromatographyofwhich was the same asan authenticsampleofscopoletin, mp197-199°C, melting-
point depression did not occur. UV spectrum (EtOH, λmax, nm): 300, 345. The IR spectrum showed absorption bands
characteristic of scopoletin. The sugar part of the hydrolysate contained glucose according to PC. Comparing our results with
the literature found that 4 was scopoletin 7-O-β-glucoside or scopolin [2].
These coumarins were isolated for the first time from A. asper growing in the Caucasus foothills on Stavropol plateau.
Pyatigorsk State Pharmaceutical Academy, 357532, Stavropol′Krai, Pyatigorsk, prosp. Kalinina, 11, Russia, fax:
88793) 32 92 67, e-mail: admin@pgfa.ru. Translated from Khimiya Prirodnykh Soedinenii, No. 6, p. 620, November-
December, 2008. Original article submitted April 8, 2008.
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009-3130/08/4406-0767 2008 Springer Science+Business Media, Inc.
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Guzhva
