Dihydrochalcone glycosides from Oxytropis myriophylla
© She et al 2011
Received: 5 September 2011
Accepted: 9 November 2011
Published: 9 November 2011
Chemical investigations of the 70% alcohol extract of Oxytropis myriophylla (Pall.) DC. (Leguminosae) have afforded the new natural product neohesperidin dihydrochalcone (1) and the known phloretin-4'-O-β-D-glucopyranoside (2), which was the first reported from the genus Oxytropis. This paper reports the isolation and full spectroscopic characterization of compounds 1 and 2 by NMR, UV, IR and MS data.
Oxytropis is an important genus of the family Leguminosae, also known as "Locoweed". The whole plant of Oxytropis myriophylla (Leguminosae) is an important Mongolian medicine, widely distributed in the southeast and northwest areas of China. It has traditionally been used to treat various diseases of rubella and influenza, applied to swelling and throat pain, together with different types of bleeding. Pharmacological research on this plant showed anti-oxidant and anti-inflammatory properties [1, 2]. Primary investigation on this plant has led to the isolation of several flavonoids, triterpene glycosides and ligans [3, 4], and in a continuation of studies on its minor constituents, the new natural product neohesperidin dihydrochalcone (1) and the known phloridzin (2), the first reported from the genus Oxytropis were obtained. This paper reports the isolation and full spectroscopic characterization of compound 1 by NMR, UV, IR and MS data.
Results and Discussion
13C (125 MHz) and1H (500 MHz) NMR spectroscopic data for 1 in DMSO-d6.
6.65 (1H, d, J = 2.0 Hz)
6.60(1H, d, J = 8.0 Hz)
6.80(1H, d, J = 8.0 Hz)
2.75(2H, t, J = 8.2 Hz)
3.27(2H, t, J = 8.2 Hz)
6.00(1 H, s)
6.00(1 H, s)
3.70 (3H, s)
5.08 (1H, d, J = 7.0 Hz)
5.04 (1H, br s)
1.25 (3H, d, J = 7.0 Hz)
In a previous study, the structure of 1 as we presented in this paper is an artificial sweetener derived from citrus, which had been synthesized by neohesperidin . The known compound, phloretin-4'-O-β-D-glucopyranoside (2) was the first reported from the Malus pumila and this compound was found to show insect-antifeedant activity . Particularly worth mentioning is phloretin-4'-O-β-D-glucopyranoside (2) is bitter, as opposed to the sweetness of 1 . The spectral data of 2 are in full agreement with those reported previously. To the best of our knowledge, the full NMR assignments of neohesperidin dihydrochalcone (1) are reported for the first time, on the basis of detailed spectroscopic analysis. And phloretin-4'-O-β-D-glucopyranoside (2) has not previously been reported from any plant of Oxytropis.
UV spectra were measured with a UV 210A Shimadzu spectrometer (Shimadzu, Kyoto, Japan). IR spectra were recorded on an IR-450 spectrometer (Shimadzu, Kyoto, Japan). 1H and 13C NMR, HMQC, HMBC, and HMQC-TOCSY spectra were performed in pyridine on a Bruker DRX-500 spectrometer (500 MHz for 1H, and 125 for 13C). ESIMS and HRESIMS were taken on an AutoSpe 3000 spectrometer (VG, Manchester, UK). The macroporous resin AB-8 (pore radius 130 ~ 140 A, Tianjin Haiguang Chemical Factory, Tianjin, China), MCI-gel CHP20P (Mitsubishi Chemical Co., Kyoto, Japan), ODS-A (YMC Co. Ltd., Kyoto, Japan), and silica gel (Qingdao Haiyang Chemical Co., Qingdao, China) were used for chromatography.
The whole plant of O. myriophylla was collected from Inner Mongolia Province, China, in June 2006, and identified by Prof. Dong Yu in Inner Mongolia Medical College. The voucher specimen (No. 0648209) was deposited with the KUN Herbarium of Kunming Institute of Botany, Chinese Academy of Sciences.
Extraction and Isolation
The whole plant (3.0 kg) of O. myriophylla was cut into small pieces and extracted with 70% EtOH at refluxed temperature, and then concentrated in vavco to yield a crude extract (256 g). The EtOH crude extract (200 g) was chromatographed on a AB-8 (10 × 100 cm) and eluted with H2O:EtOH (1:0 - 0:1) and to give six fractions (0%, 30%, 50%, 70%, 90% and 100% EtOH fractions). The 70% EtOH fraction (12 g) was purified by MCI-gel CHP20P and ODS-A eluted with a step gradient of H2O:MeOH (1:0 - 0:1), and silica gel (CHCl3:MeOH:H2O, 9:1:0.1 - 7:3:0.5), respectively, to give 1 (12 mg) and 2 (27 mg).
- She GM, Sun FF, Lv HN, Liu B: Radical scavenging activity of Oxtropis myriophylla. Chinese Journal of Experimental Traditional Medical Formulae. 2010, 16: 91-94.Google Scholar
- Lu JH, Liu Y, Zhao YY, Tu GZ: New flavonoids from Oxytropis myriophylla. Chem Pharm Bull. 2004, 52: 276-278. 10.1248/cpb.52.276.View ArticleGoogle Scholar
- She GM, Sun FF, Liu B: Three new flavonoid glycosides from Oxytropis myriophylla. J Nat Med. 2011, 65: 1-5. 10.1007/s11418-010-0442-5.View ArticleGoogle Scholar
- She GM, Sun FF, Liu B: A new ligan from Oxytropis myriophylla. Nat Prod Res. 2011, Google Scholar
- El-Naggar SF, El-Feraly FS, Foos JS, Doskotch RW: Flavonoids from the leaves of Kalmia latifolia. J Nat Prod. 1980, 43: 739-751. 10.1021/np50012a008.View ArticleGoogle Scholar
- Gent JF, Bartoshuk LM: Sweetness of sucrose, neohesperidin dihydrochalcone, and saccharin is related to genetic ability to taste the bitter substance 6-n-propylthiouracil. Chem Senses. 1982, 7: 265-272.View ArticleGoogle Scholar
- Kubo I, Matsumoto A: Isolation of an insect-antifeedant, phloretin 4'-O-β-D-glucopyranoside, by rotation locular counter-current chromatography and determination of its preferred conformation in solution by nuclear magnetic resonance analysis. Chem Pharm Bull. 1985, 33: 3817-3820.View ArticleGoogle Scholar