Chemistry of Natural Compounds, Vol. 38, No. 2, 2002
FLAVONOIDS OF Geranium pusillum
K. B. Kobakhidze and M. D. Alaniya
UDC 547.972
In continuation of a study of the flavonoids of the epigeal part of
L. (Geraniaceae) [1], air-dried
Geranium pusillum
raw material that was collected during flowering was exhaustively extracted with ethanol (70%). The alcohol extract was
evaporated in vacuum. The moist solid was treated with CHCl to remove lipophilic substances. Flavonoids were extracted
3
from the purified moist solid by ethylacetate (average 2% yield).
The ethylacetate fraction was chromatographed over a polyamide column (eluent ethanol—water in various
proportions). Repeated rechromatography of the separate fractions gave flavonoid-like 1-6. Bryant cyanidin reaction [2]
established that two of these were aglycones whereas the others were glycosides.
The isolated flavonoids were identified using UV and IR spectra and chemical transformations compared with authentic
samples.
Quercetin (1) (3,5,7,3′,4′-pentahydroxyflavone), yellow crystals, C15H10O7, mp 310-312°C, R 0.36 (BAW, 4:1:2), 0.03
f
(15% CH COOH), UV spectrum (MeOH, λmax, nm): 255, 364 sh, 370. The IR spectrum contains absorption bands for hydroxyl
3
(3385-3300 cm-1), γ-pyrone carbonyl (1660 cm-1), and aromatic C C (1565, 1516 cm-1).
Acetylation of 1 by acetic anhydride in pyridine gave the pentaacetate with mp 196-198°C. Alkali fusion with KOH
gave fluoroglucinol and protocatechuic acid [3, 4].
Kaempferol (2) (3,5,7,4′-tetrahydroxyflavone), yellow needles, C15H10O6, mp 276-278°C, R 0.88 (BAW, 4:1:2), 0.05
f
(15% CH COOH), UV spectrum (EtOH, λmax, nm): 265, 370. The IR spectrum contains absorption bands for hydroxyl (3400,
3
3300 cm-1), γ-pyrone carbonyl (1650 cm-1), and aromatic C C (1580, 1540 cm-1).
Acetylation of 2 by acetic anhydride in pyridine provided the tetraacetate with mp 184-186°C. Alkali fusion with KOH
gives fluoroglucinol and p-hydroxybenzoic acid [4].
Hyperin (3) (quercetin-3-O-β-D-galactoside), light yellow needles, C21H20O12, mp 236-238°C, [α]D20 -59.0° (c 0.1,
CH OH), R 0.54 (BAW, 4:1:2), 0.36 (15% CH COOH), UV spectrum (EtOH, λmax, nm): 259, 360. Acid hydrolysis gave
f
3
3
quercetin and D-galactose [4, 5].
Trifolin (4) (kaempferol-3-O-β-D-galactoside), yellow crystals, C21H20O11, mp 259-260°C, [α]D -35.0°C (c 0.1,
C H OH), R 0.78 (BAW, 4:1:2), 0.24 (15% CH COOH), UV spectrum (MeOH, λmax, nm): 267, 354. Acid hydrolysis gave
20
f
2
5
3
kaempferol and D-galactose [4, 6].
Avicularin (5) (quercetin-3-O-α-L-arabofuranoside), light yellow needles, C20H18O11, mp 208-210°C, [α]D20 -159°C
(c 0.1, C H OH), R 0.65 (BAW 4:1:2), 0.28 (15% CH COOH), UV spectrum (EtOH, λmax, nm): 260, 360.
f
2
5
3
Acid hydrolysis gave quercetin and L-arabinose. Acetylation gave an acetyl derivative with mp 184-185°C. Mixing
a sample of the acetyl derivative and an authentic sample of acetylated avicularin did not depress the melting point [4, 7].
Compound 6, yellow crystals, mp 205-209°C, R 0.46 (BAW, 4:1:2), UV spectrum (MeOH, λmax, nm): 270, 350. Acid
f
hydrolysis gave kaempferol, D-xylose, and D-galactose. The yield of aglycone was 46%. This indicates that the flavonoid is
a bioside. The structure of this flavonoid is under investigation.
REFERENCES
1.
2.
K. B. Kobakhidze, M. L. Alaniya, and J. N. Aneli, Khim. Prir. Soedin., 803 (1999).
E. F. Bryant, J. Am. Pharm. Assoc., 39, 480 (1950).
I. G. Kutateladze Institute of Pharmacochemistry, Academy of Sciences of Georgia. Translated from Khimiya
Prirodnykh Soedinenii, No. 2, p. 162, March-April, 2002. Original article submitted April 8, 2002.
0009-3130/02/3802-0196$27.00 ©2002 Plenum Publishing Corporation
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