全 文 ： 2010 年 11 第 8 卷 第 6 期 Chin J Nat Med Nov. 2010 Vol. 8 No. 6 411
Chinese Journal of Natural Medicines 2010, 8(6): 0411−0413
doi: 10.3724/SP.J.1009.2010.00411
Chinese
Journal of
Natural
Medicines
A New C-glycosylflavone from Pogonatherum crinitum
ZHU Di1, YANG Jie2, LAI Mao-Xiang3, WANG Qiang2*
1Changzhou College of Higher Health Vocational Technology, Changzhou 213000, China;
2Department of Chinese Materia Medica Analysis, China Pharmaceutical University, Nanjing, 210009, China;
3Guangxi Academy of Chinese Medicine and Pharmaceutical Science, Nanning 530022, China
Available online 20 Nov. 2010
[ABSTRACT] AIM: To investigate the chemical constituents from Pogonatherum crinitum (Thunb.) Kunth. METHODS: Com-
pounds were separated by column chromatography with silica gel, polyamide and Sephadex LH-20. Their structures were elucidated on
the basis of spectral data. RESULTS: A new C-glycosylflavone was isolated and the structure was identified as luteolin 6-C-β- boivi-
nopyranoside-7-O-β-glucopyranoside (1). CONCLUSION: Compound 1 is a new C-glycosylflavone.
[KEY WORDS] Pogonatherum crinitum; C-glycosylflavones; Boivinose; Structure elucidation
[CLC Number] R284.1 [Document code] A [Article ID] 1672-3651(2010)06-0411-03
1 Introduction
Pogonatherum crinitum (Thunb.) Kunth (Gramineae),
widely distributed in India and south of the Yangtze River in
China, has been used as a folk remedy for diabetes, urethritis
and nephritis [1]. Pharmacological researches have revealed
that the extract of P. crinitum could reduce the blood sugar
level in vivo and inhibit NO production in vitro [2-3]. However,
till now there is only one report concerning its active princi-
ples [3]. For the purpose of elucidating the active components
of this traditional medicine, the herb of P. crinitum was phy-
tochemically investigated. As a result, two new flavonoid
C-glycosides, compounds 1 and 2, were isolated from this
plant.
Compound 2 has been reported as apigenin 6-C-β-
boivinopyranoside-7-O-β-glucopyranoside by us before [4].
And this time, we elucidated the structure of the new com-
pound 1 (Fig. 1) by 1D and 2D NMR experiments.
2 Results and Discussion
Compound 1 was obtained as yellow powder. The mo-
lecular formula C2 7H3 0O1 4 was established from
HR-TOF-MS, which gave a pseudomolecular ion peak at m/z
577.154 9 [M - H]-. The IR spectrum of 1 indicated the
[Received on] 07-May-2010
[*Corresponding author] WANG Qiang: Prof, Tel: 86-25-
85391253, Fax: 86-25-85301528, E-mail: qwang49@163.com
These authors have no any conflict of interest to declare.
Fig. 1 Key HMBC (H C) and COSY( ) corre-
lations of compound 1
presence of hydroxyl (3 441 cm−1), a carbonyl (1 652 cm−1)
and an aromatic (1 612 cm−1) group. UV maxima occurred at
350 nm (band I) and 270 nm (band II), being characteristic of
a flavonoid system.
The 1H NMR spectrum showed two singlets at δH 6.76
(1H, s) and 6.91 (1H, s) attributed respectively to H-3 and
H-8 as well as an ABX coupled aromatic system at δH 7.40
(1H, d, J = 2.2 Hz), 6.89 (1H, dd, J = 8.1, 2.2 Hz) and 7.44
(1H, d, J = 8.1 Hz), ascribable to respective H-2′, H-6′ and
H-5′ in addition to three hydroxyl signals at δH 13.56, 9.96
and 9.37. Complex signals appeared at δH 5.31-1.05, among
which two anomeric protons emerged at δH 5.31 (1H, dd, J =
12.0, 2.3 Hz) and 4.88 (1H, d, J =7.5 Hz). In association with
its 13C NMR data (Table 1), compound 1 was characteristic
of a luteolin skeleton [5] with two sugar moieties.
In the HSQC spectrum, the two anomeric protons [δH-1′′
ZHU Di, et al. /Chinese Journal of Natural Medicines 2010, 8(6): 411−413
412 Chin J Nat Med Nov. 2010 Vol. 8 No. 6 2010 年 11 月 第 8 卷 第 6 期
Table 1 NMR Data of compound 1 (DMSO-d6) (1H: 500 MHz; 13C: 125 MHz)
Position δC δH (J: Hz) Position δC δH (J: Hz)
2 164.3 Boivinose
3 103.2 6.76, s 1〞 64.7 5.31, dd (12, 2.3)
4 181.9 2〞 30.0 ax2.89, dt (12, 2.8)
5 157.9 eq1.25, br d (13)
6 112.0 3〞 67.2 3.86, d-like (2.8)
7 163.0 4〞 69.8 3.19, d-like (3.7)
8 94.6 6.91, s 5〞 70.0 3.89, q (6.3)
9 156.2 6〞 17.0 1.05, d (6.6)
10 105.0 Glucose
1′ 121.2 1′′′ 102.0 4.88, d (7.6)
2′ 113.5 7.40, d (2.2) 2′′′ 73.6 3.35, m
3′ 145.7 3′′′ 77.3 3.42, m
4′ 149.8 5′′′ 69.2 3.20, m
5′ 115.9 6.89, d (8.2) 5′′′ 75.1 3.29, m
6′ 119.0 7.44, dd (8.2, 2.2) 6′′′ 60.7 3.79, dd (10.2, 5.2)
3.53, dd (10.2, 6.0)
5.31 (dd, J = 12.0, 2.3 Hz) and δH-1′′′ 4.88 (d, J =7.5 Hz)]
correlated respectively with δ 64.7 (C-1′′) and δ 102.0 (C-1′′′).
The coupling constants of two anomeric protons indicated
that each sugar moiety was connected to luteolin via a
β-linkage [6].
In the COSY spectrum (Fig. 1), the anomeric proton
H-1〞 (δH 5.31) was coupled to two nonequivalent geminal
protons at δH 2.89 and 1.25, assigned to H-2〞. Further obser-
vation of cross peaks including δH 2.89/δH 3.86, δH 1.25/δH
3.86, δH 3.86/δH 3.19, δH 3.19/δH 3.89 and δH 3.89/δH 1.05
permitted the assignment of H-3〞, H-4〞, H-5〞and H-6〞, re-
spectively.
The axial proton at C-2〞appeared as a double- triplet (δH
2.89, J = 12, 2.8 Hz) which coupled with the geminal proton,
the axial protons at C-1〞and the protons at C-3〞 (δH 3.86,
d-like, J = 2.8 Hz). Judging from the coupling pattern of H-2〞
and H-3〞 [7], the configuration of H-3〞 was supposed to be
equatorial. The signal due to H-4〞appeared at δH 3.19 and did
not show a detectable large coupling constant with H-3〞 while
the signal due to H-5〞 resonated at δH 3.89 (1H, quart., J = 6.3
Hz) and no coupling with H-4〞 indicating [7] the equatorial
orientation of H-4〞 and axial orientation of H-5〞. Conse-
quently, the structure of this sugar was finally deduced to be
β-boivinose. This can be confirmed from the ROESY (Fig. 2)
correlation between H-3〞 and H-2〞a and by a mutual correla-
tions of H-5〞 to H-4〞 , H-2〞 e and H-1〞 . In a similar way,
HSQC, COSY and ROESY experiments indicated that the
anomeric proton at δ 4.88 (1H, d, J = 7.5 Hz) was that of
β-glucose.
A long-range correlation, observed in HMBC experi-
ment (Fig. 1), between C-7 (δC 163.0) of apigenin nucleus
and the anomeric proton of glucose (δH 4.88) determined that
Fig. 2 Key ROESY (H H) correlations of com-
pound 1
this was the site of glucosylation. The β-boivinopyranoside
attached at C-6 through a C-linkage was evident from the
chemical shift of C-6 at δ 112.0 because in flavones with an
unsubstituted sugar moiety at this position, C-6 was expected
around δC 99.0 [7-8]. This can be confirmed by the HMBC
correlation of 5-OH (δH 13.56) to C-6 (δC 112.0) and the
ROESY correlation of 5-OH (δH 13.56) to H-1〞(δH 5.31).
Consequently, compound 1 was determined to be luteo-
lin 6-C-β-boivinopyranoside -7-O-β-glucopyranoside.
3 Experimental
3.1 General experimental procedures
Silica gel (Qingdao Marine Chemical Co., Ltd.), Poly-
amide (30-60 mesh, Taizhou Luqiao Biochemical Plastic
Co.), Sephadex LH-20 (20-100 μm,Pharmacia) were used for
CC. Optical rotations were measured with a JASCO P-1020
polarimeter (cell length: 1.0 dm). UV spectra were recorded
on a Shimadzu UV-2501PC spectrophotometer. IR spectra
(KBr discs) were recorded with a Nicolet Impact-410 spec-
trometer. Mass spectra were obtained on an Agilent liquid
chromatography/mass selective detector (LC/MSD) TOF.
ZHU Di, et al. /Chinese Journal of Natural Medicines 2010, 8(6): 411−413
2010 年 11 月 第 8 卷 第 6 期 Chin J Nat Med Nov. 2010 Vol. 8 No. 6 413
3.2 Plant material
The whole plant of Pogonatherum crinitum (Thunb.)
Kunth was collected from Nanning, Guangxi province, China
in April 2007 and authenticated by Prof. WANG Qiang. A
voucher specimen (No. FB-070825) has been deposited at the
Department of Chinese Materia Medica Analysis, China
Pharmaceutical University for future analysis.
3.3 Extraction and isolation
The whole plants (15 kg) of P.crinitum were shade dried,
chopped and exhaustively extracted with 70% ethanol three
times. The extract was concentrated under vacuum, diluted
with water and partitioned with petroleum ether, CHCl3 and
n-BuOH. The n-BuOH-soluble fraction (500 g) was separated
by column chromatography on silica gel, eluted with a
CHCl3-MeOH gradient of increasing polarity to give three
fractions: Fr1 (3.5g CHCl3-MeOH 97∶3), Fr2 (12 g CHCl3-
MeOH 95∶5) and Fr3 (150 g CHCl3-MeOH 85∶15-80∶
20). Fr1 and Fr2 were separately chromatographed on
Sephadex LH-20 (MeOH-H2O 1∶1), to yield tricin (10 mg)
and quercetin 7-O-rhamnoside (8 mg) respectively. Fr3 was
subjected to polyamide column by successive elution with
EtOH-H2O (10∶90→90∶10). The elute of 30% EtOH was
evaporated to dryness (34 g) under reduced pressure at 70 °C
and redissolved in MeOH solvent, and then a small amount
of yellow powder was produced (4 g) which were further
purified by repeated column chromatography on Sephadex
LH-20 using 60% MeOH as eluent, yielding compounds 1
(158 mg) and 2 (200 mg).
3.4 luteolin 6-C-β-boivinopyranoside-7-O-β-glucopyrano-
side (1):
Yellow powder; mp 274-276 °C; [α] D24 – 66° (c 0.0600,
MeOH); UV λmax (MeOH) nm (logε): 350 (3.8), 270 (4.0); IR
(KBr) υmax 3 441, 1 652, 1 612, 1 486 cm−1; 1H NMR
(DMSO-d6, 500 MHz) and 13C NMR (DMSO-d6, 125 MHz)
data, see Table 1; HR-TOF-MS [M - H] − m/z 577.165 2
(Calcd. for C27H30O14, 577.165 2).
3.5 Acidic hydrolysis of luteolin 6-C-β-boivinopyranoside-
7-O-β-glucopyranoside (1):
Compound 1 (33.6 mg) was dissolved in 2 mol·L−1
H2SO4 (5 mL) and the solution was refluxed for 3.5 h. The
resulting precipitates were removed by filtration and the fil-
trate was neutralized with 2 mol·L−1 Ba(OH)2. The precipi-
tants were again removed by filters, with the filtrate evapo-
rated in vacuo to give a residue (11.7 mg) [6], [α]D24 −66° (c
0.16, H2O), which was identified as D-glucose
byco-chromatography on silica gel plate with an authentic
sample (solvent: n-BuOH-Me2CO-H2O 4∶5∶1, Rf 0.53).
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金丝草中的新黄酮碳苷
朱 迪 1, 杨 杰 2, 赖茂祥 3, 王 强 2*
1常州卫生高等职业技术学校, 常州 213000;
2中国药科大学中药分析教研室, 南京 210009;
3广西中医药研究院, 南宁 530022
【摘 要】 目的：研究金丝草(Pogonatherum crinitum)的化学成分。方法：应用硅胶柱, 聚酰胺柱和 SephadexLH-20 方法分
离和纯化化合物, 通过光谱方法及理化性质鉴定化合物结构。结果：分离得到 1 个黄酮碳苷木犀草素 6-C-β-波依文糖-7-O-β-葡
萄糖苷(1)。结论：化合物 1 为新的黄酮碳苷。
【关键词】 金丝草; 黄酮碳苷; 波依文糖; 结构解析