全 文 ： 2009 年 5 月 第 7 卷 第 3 期 Chin J Nat Med May 2009 Vol. 7 No. 3 184

Chinese Journal of Natural Medicines 7 (2009) 0184−0186
doi: 10.3724/SP.J.1009.2009.00184
Chinese
Journal of
Natural
Medicines







A new C-glycosylflavone from Pogonatherum crinitum
ZHU Di1, YANG Jie1, DENG Xue-Tao1, LAI Mao-Xiang2, WANG Qiang1*
1Department of Chinese Material Medica Analysis, China pharmaceutical University, Nanjing, 210038;
2Guangxi Academy of Chinese Medicine and Pharmaceutical Science, Guangxi 530022, China
Available online 20 May 2009
【ABSTRACT】 AIM: To investigate the chemical constituents from Pogonatherum crinitum (Thunb.) Kunth. METHODS: The
compounds were separated by column chromatography with silica gel, Polyamide and Sephadex LH-20. Their structures were eluci-
dated on the basis of spectral data. RESULTS: Three flavones were isolated and the structures were identified as apigenin
6-C-β-boivinopyranosyl-7-O-β-glucopyranoside(1), tricin(2) and quercetin 7-O-rhamnoside (3).CONCLUSION: Compound 1 is a
new C-glycosylflavone and compounds 2~3 were isolated from the genus Pogonatherum for the first time.
【KEY WORDS】 Pogonatherum crinitum; C-glycosylflavones; Boivinose; Structure elucidation
【CLC Number】 R284.1 【Document code】 A 【Article ID】1672-3651(2009)03-0184-03

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, a new C-boivinopyra-
nosylflavone (1) (Fig.1) together with two known flavones
were isolated from this plant. This is the first report of two
known compounds from the genus Pogonatherum.
2 Results and Discussion
Compound 1 was obtained as yellow powder. The mo-
lecular formula C27H30O13 was established from HR-TOF-
MS which gave a pseudomolecular ion peak at m/z 561.159 1
[M – H]-. The IR spectrum of 1 indicated the presence of
hydroxyl (3 424 cm−1), a carbonyl (1 652 cm−1) and an aro-
matic (1 609 cm−1) group. UV maxima occurred at 333 nm
(band I) and 285 nm (band II), characteristic of a flavonoid
system.
The 1H NMR spectrum showed two singlets at δH 6.88

【Received on】 2009-01-04
【*Corresponding author】 Wang Qiang: Prof., Tel: +86-25-8539
1253; Fax: +86-25-85301528，E-mail: qwang49@163. com
(1H, s) and 6.96 (1H, s) attributed respectively to H-3 and
H-8 as well as an AA′BB′ spin system at δ 6.94 and 7.95,
typical of a 4′-monosubstituted B-ring of flavonoid. Corre-
spondingly, its 13C NMR data showed two resonances of
equivalent carbon [δC 128.4 (C-2′ and C-6′), δC 115.9
(C-3′and C-5′)] . Two anomeric protons emerged at δH 5.31
(1H, dd, J = 2.3, 12.0 Hz) and 4.86 (1H, d, J = 7.6 Hz) corre-
lated respectively with δ 64.6 (C-1〞) and δ 102.0 (C-1′′′) in
the HSQC spectrum. In association with its 13C NMR data
(Table 1), compound 1 was characteristic of an apigenin
skeleton [4] with two sugar moieties. The coupling constants
of two anomeric protons indicated that each sugar moiety
was connected to apigenin via a β-linkage[5].
In the COSY spectrum (Fig. 1), the anomeric proton H-
1〞 (δH 5.31) was coupled to two nonequivalent geminal pro-
tons at δH 2.90 and 1.25, assigned to H-2〞. Further observa-
tion of cross peaks including δH 2.90/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 permit-
ted the assignments of H-3〞, H-4〞, H-5〞and H-6〞, respec-
tively.
The axial proton at C-2〞appeared as a double- triplet (δH
2.90, J = 2.7,12 Hz) coupled with the geminal proton, the
axial protons at C-1〞and the protons at C-3〞 (δH 3.86, d- like, J
= 2.7 Hz).Judging from the coupling pattern of H-2〞and H-3〞
[6], 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, q, J = 6.3 Hz) and no
coupling with H-4〞 indicating [6] the equatorial orientation
ZHU Di, et al. /Chinese Journal of Natural Medicines 2009, 7(3): 184−186
2009 年 5 月 第 7 卷 第 3 期 Chin J Nat Med May 2009 Vol. 7 No. 3 185


Fig. 1 Structure and Key HMBC (H C), COSY( ) and ROESY (H H) correlations of compound 1

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)
2 164.1 Boivinose
3 103.2 6.88, s 1〞 64.6 5.31,dd ( 12,2.3 )
4 182.0 2〞 30.0 ax2.90,dt ( 12,2.7 )
5 157.8 eq1.25,br,d ( 13 )
6 112.9 3〞 67.1 3.86, d-like ( 2.7 )
7 163.0 4〞 69.8 3.19, d-like ( 3.7 )
8 094.7 6.96, s 5〞 70.0 3.89, q ( 6.3 )
9 156.1 6〞 17.1 1.05, d ( 6.6 )
10 105.0 Glucose
1′ 120.8 1′′′ 102.0 4.86, d ( 7.6 )
2′ 128.4 7.95, d ( 8.8 ) 2′′′ 73.6 3.34,m
3′ 115.9 6.94,d ( 8.8 ) 3′′′ 77.3 3.40,m
4′ 161.0 5′′′ 69.2 3.20,m
5′ 115.9 6.94, d ( 8.8 ) 5′′′ 75.1 3.29, m
6′ 128.4 7.95, d ( 8.8 ) 6′′′ 60.1 3.80, dd (10.9, 5.3)
3.52, dd (10.9, 6.0)

of H-4〞and axial orientation of H-5〞. Consequently, the
structure of this sugar was finally deduced to be
β-boivinose .This can be confirmed from the ROESY (Fig. 1)
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 another ano-
meric proton δ 4.86 (1H, d, J = 7.6 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 4.86) determined that
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 δ112.9 because in flavones with an
unsubstituted sugar moiety at this position, C-6 was expected
around δC 99.0 [4,7]. This can be confirmed by the HMBC
correlation of 5-OH (δH 13.53) to C-6 (δC 112.9) and the
ROESY correlation of 5-OH (δH 13.53) to H-1〞(δH 5.31).
Consequently, 1 was determined to be apigenin 6-C-β-
boivinopyranosyl -7-O-β-glucopyranoside
Compounds 2-3 were characterized as tricin (2) and
quercetin 7-O-rhamnoside (3) by comparison of the physical
and spectral data with the literature. Their spectral data are as
follows:
Compound 2 C17H14O7, yellow power, mp 279-281°C.
ESI-MS m/z 331 [M + H]+ 1. H NMR (500 MHz, DMSO-d6)
δ: 12.96 (s, 1H, -OH), 10.78 (s, 1H, -OH) 9.30 (s, 1H, -OH),
7.32 (s, 2 H, J = 2.0 Hz, H-2,6), 6.98 (s, 1H, H-3), 6.56 (d,
1H, J =2.0 Hz, H-8), 6.20 (d, 1H, J = 2.0 Hz, H-6), 3.88 (s,
6H, 3, 5-OCH3). 13C NMR (125 MHz, DMSO -d6) δ: 56.2 (3,
5-OCH3), 94.2 (C-8), 98.9 (C-6), 103.5 (C-3), 104.2 (C-10),
103.5 (C-2, 6), 120.3 (C-1), 139.3 (C-4), 147.8 (C-3, 5),
157.2 (C-9), 161.3 (C-5), 163.7 (C-7), 163.2 (C-2), 181.6
(C-4) [8].
Compound 3 C21H20O11, yellow powder, mp 174-176
°C. ESI-MS m/z 449 [M + H]+. 1H NMR (500 MHz, DMSO-
d6) δ: 12.47 ( s, 1H, -OH), 9.59 (s, 1H, -OH), 9.46 (s, 1H,
-OH), 9.26 ( s, 1H, -OH), 7.72 (d, 1H, J = 2.0 Hz, H-2), 7.59
(dd, 1H, J = 2.0, 9.0 Hz, H-6), 6.89 (d, 1H, J = 9.0 Hz, H-5),
6.78 (d, 1H, J = 2.0 Hz, H-8),6.41 (d, 1H, J = 2.0 Hz, H-6),
5.54 ( s, 1H, H-1), 5.10 (d, 1H, H-1〞 , J = 4.0 Hz) 4.48 (d, 1H,
J = 5.0 Hz), 4.47 (m, 2H), 3.84 (s, 1H), 3.64 (m, 1H), 1.13 (d,
3H, J = 6.0 Hz, Rha -Me). 13C NMR (125 MHz, DMSO-d6) δ:
17.9 (C-6〞), 69.7 (C-5〞), 70.0 (C-2〞), 70.2 (C-3〞), 71.5 (C-4〞),
94.1 (C-8), 98.2 (C-1〞), 98.7 (C-6), 104.6 (C-10), 115.2
(C-5), 115.4 (C-2), 120.1 (C-6), 121.6 (C-1), 136.1 (C-3),
145.0 (C-3), 147.4 (C-4), 147.7 (C-2), 155.6 (C-9), 160.2
(C-5), 161.4 (C-7), 175.8 (C-4)[9].
3 Experimental
3.1 General experimental procedures
Silica gel (Qingdao Marine Chemical Co., Ltd.), Poly-
amide (30-60 mesh, Taizhou Luqiao Biochemical plastic Co.),
ZHU Di, et al. /Chinese Journal of Natural Medicines 2009, 7(3): 184−186
186 Chin J Nat Med May 2009 Vol. 7 No. 3 2009 年 5 月 第 7 卷 第 3 期

Sephadex LH-20 (20-100 μm, Pharmacia). Optical rotations
were measured with a JASCO P-1020 polarimeter (cell leng-
th: 1.0 dm). UV spectra were recorded on a Shimadzu UV-
2501PC spectrophotometer. IR spectra (KBr discs) were re-
corded with a Nicolet Impact-410 spectrometer. Mass spectra
were obtained on an Agilent liquid chromatographer/mass
selective detector (LC/MSD) TOF.
3.2 Plant material
The whole plant of Pogonatherum crinitum (Thunb.)
Kunth was collected from Guangxi province, China, 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 sepa-
rated by column chromatography on silica gel, eluted with a
CHCl3-MeOH gradient of increasing polarity to give three
fractions: Fr1 (CHCl3-MeOH 97∶ 3), Fr2 (CHCl3-MeOH
95∶5) and Fr3 (CHCl3-MeOH 85∶15–80∶20). Fr1 and Fr2
were separately chromatographed on Sephadex LH-20
(MeOH-H2O 1∶1), with Fr1 yielding tricin (2, 10 mg) and
Fr2 yielding quercetin 7-O-rhamnoside (3, 8 mg). Fr3 was
subjected to polyamide column by successive elution with
EtOH-H2O (10∶90–90∶10). The eluent of 30% EtOH was
evaporated to dryness under reduced pressure at 70 °C and
redissolved in MeOH solvent, then a small amount of yellow
powder further purified by repeated column chromatography
on Sephadex LH-20 using 60% MeOH as eluent, yielding
compound 1 (200 mg).
3.4 apigenin 6-C-β-boivinopyranosyl-7-O-β-glucopyrano-
side (1):
Yellow powder; mp 266–268 °C; [α]24D – 40° (c 0.0565,
MeOH); UV λmax (MeOH) nm (logε): 333 (4.4), 285 (3.2); IR
(KBr) υmax cm−1 3 424, 1 652, 1 609, 1 484, 1 350; NMR
data, see Table 1; HR-TOF-MS [M – H]− m/z 561.159 1
(Calcd. for C27H30O13, 561.161 3).
3.5 Acidic hydrolysis of apigenin 6-C-β-boivinopyranosyl-
7-O-β-glucopyranoside (1):
Compound 1 (32.4 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 neutralized with 2 mol·L-1 Ba(OH)2. The precipitates
were again removed by filtration, with the filtrate evaporated
in vacuo to give a residue (11.2 mg)[6], [α]
24
D + 42° (c 0.16,
H2O), which was identified as D-glucose by co-chroma-
tography on silica gel plate by comparison with an authentic
sample (solvent: n-BuOH-Me2CO-H2O 4∶5∶1, Rf 0.52).
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金丝草中的一个新黄酮碳苷
朱 迪 1, 杨 杰 1, 邓雪涛 1, 赖茂祥 2, 王 强*
1 中国药科大学中药分析教研室, 南京 210038;
2 广西中医药研究院, 广西 530022
【摘 要】 目的：研究金丝草(Pogonatherum crinitum)的化学成分。方法： 应用硅胶柱层析、聚酰胺柱层析和 SephadexLH-20
柱层析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 3 个黄酮类化合物, 分别为：芹菜素
6-C-β-波依文糖-7-O-β-葡萄糖苷(1)、苜蓿素(2)和槲皮素 7-O-鼠李糖(3)。结论：化合物 1 为新的黄酮碳苷, 化合物 2~3 为首次从
金发草属中得到。
【关键词】 金丝草; 黄酮碳苷; 波依文糖; 结构解析