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

Bin Liu

Gaimei She

GM She

I Kubo

JF Gent

JH Lu

SF El-Naggar

Si Wang

English

PubMed

Springer - Publisher Connector

RESEARCH ARTICLE Open Access
Dihydrochalcone glycosides from Oxytropis
myriophylla
Gaimei She, Si Wang and Bin Liu*
Abstract
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-b-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.
Background
Oxytropis is an important genus of the family Legumi-
nosae, 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 differ-
ent types of bleeding. Pharmacological research on this
plant showed anti-oxidant and anti-inflammatory prop-
erties [1,2]. Primary investigation on this plant has led
to the isolation of several flavonoids, triterpene glyco-
sides and ligans [3,4], and in a continuation of studies
on its minor constituents, the new natural product neo-
hesperidin dihydrochalcone (1) and the known phlorid-
zin (2), the first reported from the genus Oxytropis were
obtained. This paper reports the isolation and full spec-
troscopic characterization of compound 1 by NMR, UV,
IR and MS data.
Results and Discussion
The phytochemical study of 70% ethanol extract
obtained from the whole plant of O. myriophylla
afforded two compounds, including a new natural pro-
duct 1 neohesperidin dihydrochalcone and a known
metabolite phloretin-4’-O-b-D-glucopyranoside (2)
(Figure 1). The structures of 1 and 2 were elucidated by
detailed spectroscopic analysis and comparison of their
spectroscopic data with those reported in the literatures.
Compound 1 was obtained as a white amorphous
powder. Its molecular formula was assigned as
C28H36O15 on the basis of the
13C NMR data and nega-
tive HRESIMS (m/z 635.19586 [M + Na]-), calcd. for
635.19519. The UV spectrum exhibited absorption max-
ima at 284 nm (band II), which were suggestive of a
dihydrochalcone skeleton. The IR spectrum of 1 illu-
strated a broad band at 3374 cm-1 and 1630 cm-1, con-
sistent with the presence of hydroxy group and carbonyl
functions. The occurrence of a dihydrochalcone skeleton
in the molecule could be easily deduced from the 1H
NMR spectrum (Table 1), in which compound 1 showed
the signals for an exchangeable proton at δ 12.23 (1H, s,
H-6’), ABX-type aromatic protons at δ {[6.65 d, J = 2.0
Hz, H- 2], 6.60 [d, J = 8.0 Hz, H-5], 6.80 [dd, J = 8.0, 2.0
Hz, H-6]} on A-ring, one singlet at high field in the aro-
matic region δ 6.00 [s, H-3’, 5’] on B-ring, together with
two mutually coupled methylene groups [δ 3.27 (2H, t, J
= 8.2 Hz, H-8) and 2.75 (2H, t, J = 8.2 Hz, H-7]. These
above data suggested the occurrence of a dihydrochal-
cone skeleton with the A-ring tri-substituted and B-ring
penta-substituted in the molecule. In addition, the 1H
NMR also exhibited signals due to one b-glucopyranosyl
unit [δ 5.08 (d, J = 7.0 Hz, H-1”)]. The J value (7.0
xbHz) of the anomeric proton concluded the b-config-
uration of the glucose moiety. These NMR features
were resembled to those of compound 2, phloretin-4’-
O-b-D-glucopyranoside [5], except for the existence of
an additional set of signals arising from one a-L-rham-
nopyranosyl [δ 5.04, (1H, br s, H-1’”) and 1.25 (3H, d, J
= 6.2 Hz, H-6’”)], a methoxyl groups [δ 3.70 (3H, s)]
reduced from 1H NMR, 13C NMR and HMQC-TOCSY
in 1. In addition, 1, 3, 4-trisubstituted phenyls in A-ring
* Correspondence: liubinyn67@163.com
School of Chinese Pharmacy, Beijing University of Chinese Medicine, Beijing,
People’s Republic of China
She et al. Chemistry Central Journal 2011, 5:71
http://journal.chemistrycentral.com/content/5/1/71
© 2011 She et al
compound 1, instead of 1, 4-disubstituted aromatic A-
rings in the above-mentioned glycoside. The attachment
of the glucopyranosyl moiety was deduced to be at C-4’
according to glycosylation rule. It is observed that the
chemical shifts of glucosyl C-2’’ was downfield shifted to
δ 77.1 in 1, from δ 74.7 in 2, suggesting that the a-L-
rhamnopyranosyl group was located at the glucosyl C-2’’
in 1. The conclusion was further confirmed by the
HMBC spectrum in which the anomeric proton of the
glucopyranosyl moiety at δ 5.08 (d, H-1’’) showed long
range correlation with C(4’) (δ 163.17). Moreover, the
other correlations of H-(OCH3) (δ 3.70) with C-3, H-1’’’
(δ 5.04) with C-2’’, respectively, in the HMBC spectrum
confirmed the structure of compound 1. Therefore, the
structure of 1 was determined to be neohesperidin
dihydrochalcone.
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 [6].
The known compound, phloretin-4’-O-b-D-glucopyra-
noside (2) was the first reported from the Malus pumila
and this compound was found to show insect-antifee-
dant activity [7]. Particularly worth mentioning is phlor-
etin-4’-O-b-D-glucopyranoside (2) is bitter, as opposed
to the sweetness of 1 [6]. 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-b-D-glucopyranoside (2) has not
previously been reported from any plant of Oxytropis.
Experimental
General
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 macro-
porous resin AB-8 (pore radius 130 ~ 140 A, Tianjin
Haiguang Chemical Factory, Tianjin, China), MCI-gel
CHP20P (Mitsubishi Chemical Co., Kyoto, Japan), ODS-
OCH3
OH
OH
O
O
O
O
HO
HO
HO
OH
O
OHHO
HO
1
OH
OH
O
O
O
OHHO
HO
HO OH
2
1'
3'
4' 2'
5' 6'
7
8
9
1 2
3
4
5
6
1''
Glc
Rha 1'''
Figure 1 Structure of compounds 1 - 2 from O. myriophylla.
Table 1 13C (125 MHz) and1H (500 MHz) NMR
spectroscopic data for 1 in DMSO-d6.
position δH δC
1 130.4
2 6.65 (1H, d, J = 2.0 Hz) 115.7
3 146.3
4 145.8
5 6.60(1H, d, J = 8.0 Hz) 112.4
6 6.80(1H, d, J = 8.0 Hz) 118.7
7 2.75(2H, t, J = 8.2 Hz) 29.4
8 3.27(2H, t, J = 8.2 Hz) 45.4
9 204.9
1’ 105.3
2’ 162.9
3’ 6.00(1 H, s) 94.8
4’ 163.7
5’ 6.00(1 H, s) 94.8
6’ 162.9
OCH3 3.70 (3H, s) 55.7
1” 5.08 (1H, d, J = 7.0 Hz) 97.1
2” 3.50 77.1
3” 3.34 76.5
4” 3.50 69.4
5” 3.37 76.8
6” 3.50~3.65 60.3
1"’ 5.04 (1H, br s) 100.6
2"’ 3.82 70.4
3"’ 3.02 70.5
4"’ 3.02 71.9
5"’ 3.82 68.3
6"’ 1.25 (3H, d, J = 7.0 Hz) 18.1
She et al. Chemistry Central Journal 2011, 5:71
http://journal.chemistrycentral.com/content/5/1/71
Page 2 of 3
A (YMC Co. Ltd., Kyoto, Japan), and silica gel (Qingdao
Haiyang Chemical Co., Qingdao, China) were used for
chromatography.
Plant material
The whole plant of O. myriophylla was collected from
Inner Mongolia Province, China, in June 2006, and iden-
tified by Prof. Dong Yu in Inner Mongolia Medical Col-
lege. The voucher specimen (No. 0648209) was
deposited with the KUN Herbarium of Kunming Insti-
tute 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 frac-
tions (0%, 30%, 50%, 70%, 90% and 100% EtOH frac-
tions). The 70% EtOH fraction (12 g) was purified by
MCI-gel CHP20P and ODS-A eluted with a step gradi-
ent 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).
Authors’ contributions
GS carried out the chemical analysis-structure elucidation and drafted the
Manuscript; SW carried out the chemical and biological studies; BL
conceived of the study and its design and coordination of the scientific
teams. All authors have read and approved the final manuscript.
Competing interests
The authors declare that they have no competing interests.
Received: 5 September 2011 Accepted: 9 November 2011
Published: 9 November 2011
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3. She GM, Sun FF, Liu B: Three new flavonoid glycosides from Oxytropis
myriophylla. J Nat Med 2011, 65:1-5.
4. She GM, Sun FF, Liu B: A new ligan from Oxytropis myriophylla. Nat Prod
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5. El-Naggar SF, El-Feraly FS, Foos JS, Doskotch RW: Flavonoids from the
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doi:10.1186/1752-153X-5-71
Cite this article as: She et al.: Dihydrochalcone glycosides from
Oxytropis myriophylla. Chemistry Central Journal 2011 5:71.
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Page 3 of 3


Dihydrochalcone glycosides from Oxytropis myriophylla

Abstract 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.</p

She Gaimei

Wang Si

Liu Bin

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Chemistry Central Journal

Dihydrochalcone glycosides from <it>Oxytropis myriophylla</it>

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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

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