Chemistry of Natural Compounds, Vol. 46, No. 4, 2010
FLAVONOL GLYCOSIDE FROM Humulus lupulus
1*
1
M. D. Alaniya, N. Sh. Kavtaradze,
UDC 547.972
1
2
2
A. V. Skhirtladze, C. Pizza, and S. Piacente
Humulus lupulus L., common hops (Canabaceae), is a medicinal plant [1]. Its fruits, so-called cones, are included in
various mixtures and preparations [2]. Information has recently appeared about the anticarcinogenic [3–5], antibiotic [6], and
antioxidant [7] activities of hops.
The chemical composition in general consists of essential oil (1–3%), bitter compounds (ꢀ- and ꢁ-acids), flavonoids,
and oligomeric proanthocyanidines [1, 8, 9]. The chemistry of hops growing in Georgia has not been studied.
Ground and air-dried hops cones were de-fatted beforehand and extracted with EtOH (80%). The alcohol was distilled
off. The aqueous residue was purified with CHCl . Flavonoids were extracted by EtOAc. Pale yellow needlelike crystals of
3
compound 1 formed at the interface of the liquids.
Compound 1, mp 194–196°C (aqueous EtOH). UV spectrum (MeOH, ꢂ , nm): 265, 350; +CH COONa: 265,
max
3
–1
350; +CH COOH + H BO : 265, 350; +AlCl : 274, 355; +AlCl + HCl: 267, 348. IR spectrum (KBr, ꢃ , cm ): 3380
3
3
3
3
3
max
(–OH); 2983, 2940 (CH –C); 1665 (ꢄ-pyrone >C=O); 1550, 1575, 1580 (aromatic –CH). Mass spectrum (70 eV, m/z, I , %):
3
rel
+
+
+
+
577 (100) [M – H] , 431 (12.5) [M – Rha] , 285 (3.12) [M – 2Rha] , 284 (4.68) [M – 2Rha – H] .
PMR spectrum (600 MHz, CD OD, ꢅ, ppm, J/Hz): 7.82 (2H, d, J = 8.8, H-2ꢆ,6ꢆ), 6.93 (2H, d, J = 8.8, H-3ꢆ,5ꢆ), 6.70
3
(1H, d, J = 2.1, H-8), 6.48 (1H, d, J = 2.1, H-6), 5.62 (1H, d, J = 1.6, H-1ꢆꢆ), 5.40 (1H, d, J = 1.6, H-1ꢆꢆꢆ), 1.32 (3H, d, J = 5.8,
Rha CH ), 0.90 (3H, d, J = 5.6, Rha CH ), 4.27–3.32 (8H, m, H-2ꢆꢆ, H-3ꢆꢆ, H-4ꢆꢆ, H-5ꢆꢆ, H-2ꢆꢆꢆ, H-3ꢆꢆꢆ, H-4ꢆꢆꢆ, H-5ꢆꢆꢆ).
3
3
13
C NMR spectrum (600 MHz, CD OD, ꢅ, ppm): 158.24 (C-2), 132.62 (C-3), 176.17 (C-4), 159.21 (C-5), 97.59
3
(C-6), 159.81 (C-7), 96.51 (C-8), 155.91 (C-9), 103.86 (C-10), 118.58 (C-1ꢆ), 129.12 (C-2ꢆ), 113.80 (C-3ꢆ), 159.03 (C-4ꢆ),
113.50 (C-5ꢆ), 128.81 (C-6ꢆ), 100.17 (C-1ꢆꢆ), 70.03 (C-2ꢆꢆ), 71.73 (C-3ꢆꢆ), 72.21 (C-4ꢆꢆ), 68.30 (C-5ꢆꢆ), 20.20 (C-6ꢆꢆ), 98.72
(C-1ꢆꢆꢆ), 70.23 (C-2ꢆꢆꢆ), 70.54 (C-3ꢆꢆꢆ), 71.82 (C-4ꢆꢆꢆ), 69.73 (C-5ꢆꢆꢆ), 17.80 (C-6ꢆꢆꢆ) [10].
The R values in n-BuOH:AcOH:H O (4:1:2) and AcOH were 0.76 and 0.53, respectively.
f
2
UV spectra obtained by adding diagnostic reagents were consistent with sugars on C-3 and C-7 of the aglycon.
Acid hydrolysis of 1 gave the aglycon kaempferol, mp 274–276°C, UV spectrum (MeOH, ꢂ , nm): 270, 355;
max
–1
IR spectrum (KBr, ꢃ, cm ): 3200–3400 (OH); 1655 (ꢄ-pyrone >C=O); 1590, 1575, 1560, (Ar), and L-rhamnose.
Basic hydrolysis [13] of 1 (70 mg) produced a monoside (43 mg), mp 182–184°C; UV spectrum (MeOH, ꢂ , nm):
max
13
255, 360. PMR and C NMR spectra of the glycoside were analogous to those of kaempferol-3-O-ꢀ-L-rhamnoside [13].
L-Rhamnose was detected in the sugar part of the hydrolysate.
Enzymatic hydrolysis of 1 (50 mg) used an enzyme from Helix plectotropis [11] and produced a monoside (32 mg),
13
mp 227–228°C; UV spectrum (MeOH, ꢂ , nm): 260, 365. PMR and C NMR spectra of the glycoside corresponded with
max
those of kaempferol-7-O-ꢀ-L-rhamnoside [13]. L-Rhamnose was detected as the sugar part.
Based on physicochemical properties, chemical transformations, and spectral analysis and a comparison with the
literature, 1 was identified as kaempferol-3,7-O-ꢀ-L-dirhamnopyranoside (lespedin) [11]. Lespedin was described for the
first time from Humulus lupulus L.
1) I. Kutateladze Institute of Pharmaceutical Chemistry, 0159, ul. P. Saradzhishvili, 36, Tbilisi, Georgia,
fax: (99532) 25 00 26, e-mail: merialania@yahoo.com; 2) Department of Pharmaceutical Sciences, University of Salerno,
Salerno, Italy. Translated from Khimiya Prirodnykh Soedinenii, No. 4, p. 540, July–August, 2010. Original article submitted
June 3, 2009.
©
0009-3130/10/4604-0641 2010 Springer Science+Business Media, Inc.
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Alaniya
