Chemical constituents from the root bark of Rodgersia sambucifolia

Article abstract of DOI:10.1002/jccs.200700013

A new demethylacetovanillochromene glycoside, 2,2-dimethyl-2H-(8-hydroxy-6- acetyl)-[2,3-b] pyran-8-O-β-D-apiofuranosyl-(1→6)-β-D- glucopyranoside (1), together with twenty-three known compounds, have been isolated from the root bark of Rodgersia sambucifolia. These known compounds include two diterpenoids, three flavonoids, two catechins, four lignans, two benzenoids, two isocoumarins, two steroids and six monoterpene glycosides, which were determined by means of spectral analyses.

Full text of DOI:10.1002/jccs.200700013

Journal of the Chinese Chemical Society, 2007, 54, 75-80
75
Chemical Constituents from the Root Bark of Rodgersia sambucifolia
Hao-Bin Hu* (
Hong Cao (
Department of Chemistry, Longdong University, Qingyang 745000, P.R. China
), Yu-Feng Jian (
),
) and Xu-Dong Zheng (
)
A new demethylacetovanillochromene glycoside, 2,2-dimethyl-2H-(8-hydroxy-6-acetyl)-[2,3-b] py-
ran-8-O-b-D-apiofuranosyl-(1®6)-b-D-glucopyranoside (1), together with twenty-three known com-
pounds, have been isolated from the root bark of Rodgersia sambucifolia. These known compounds in-
clude two diterpenoids, three flavonoids, two catechins, four lignans, two benzenoids, two isocoumarins,
two steroids and six monoterpene glycosides, which were determined by means of spectral analyses.
Keywords: Rodgersia sambucifolia; Saxifragaceae; Root bark; Demethylacetovanillochromene
glycoside.
INTRODUCTION
There are about 5 species and 3 variations in the ge-
[M+H]+, and the molecular formula was determined as
C24H32O12 by high-resolution FAB-MS at m/z 512.1904
(calcd. for C24H32O12, 512.1894), giving 1 an unsaturation
index of 9. The Molisch test showed it to be a glycoside,
and this was also indicated by its IR spectrum which exhib-
ited the absorption bands at 3018 (Ar-H), 1658 (>C=O),
1610, 1595, 1485 (aromatic ring), 1088, 1070, 1036 (pyr-
anose C-H), 1270, 1126 and 880 (vinyl ether), 1370 and
1384 (gem-dimethyl), and 870 cm-1 (tetrasubstituted aryl).
The 13C NMR and DEPT spectra of 1 clearly exhibited 24
carbon signals (3 ´ CH3, 3 ´ CH2, 11 ´ CH, 7 ´ C). The 1H
NMR signals at the range of 3.10 to 5.30 and eleven 13C
NMR signals at the range of 64 to 112 (dC 104.6, 75.4, 78.1,
71.2, 77.2, 68.2 for glucose unit, and dC 111.1, 77.2, 80.1,
75.5, 64.9 for apiose unit) suggested the existence of di-
saccharides.
nus Rodgersia (Saxifragaceae), which are mainly distrib-
uted in East Asia. Some of them are used as traditional
medicines which have anti-bacterial, anti-virus, antalgic,
anti-inflammatory, hemostatic, anti-rheumatic and anti-
tussive activities.1,2 Previous studies have indicated that
tannins, monoterpenoids and related polyphenols are the
main constituents in this genus.3 Rodgersia sambucifolia
(Chinese name “xinanguidengqing”) is a traditional Chi-
nese folk medicine for treating rheumatism, diarrhoea and
having a strong effect on antiphlogistic, analgesic, and as-
tringent conditions and on stopping bleeding, etc. It is
mainly distributed in Yunnan, Guizhou and Sichuan prov-
inces of China.4 However, very little is known about its
chemical constituents.5 To systematically investigate the
chemical constituents, we examined the root bark of R.
sambucifolia and finally isolated twenty-four compounds,
including a new one (1), from the methanolic extract. The
present paper deals with the isolation and structural identi-
fication of the new compound.
Besides signals for sugars, thirteen additional signals
assigned to the aglycone moiety, including an acetyl (dC
196.8 and 25.7) and a gem-dimethylchromene ring (dC
125.8, 115.8 for olefinic carbons, dC 120.9, 131.2, 116.7,
146.7, 158.9 and 105.7 for aromatic carbons, dC 76.8 for
saturated quaternary carbon, and 25.7 ´ 2 for gem-dimethyl
carbons) were recognized in 13C NMR and DEPT (90° and
135°). The 1H NMR spectrum of 1 also revealed an ortho-
coupled doublets at dH 5.64 and 6.62 (1H each, d, J = 10.0
Hz, olefonic protons) and 6H singlet at dH 1.46 (3H, s, di-
methyl protons), indicating the presence of a 2,2-dimethyl-
chromene system.6 Moreover, the 1H NMR spectrum showed
that no long range coupling existed between any of the
chromenic and aryl protons except for 2H meta-coupled
protons at dH 7.21 and 7.42 (1H each, d, J = 2.0 Hz, aro-
RESULTS AND DISCUSSION
The methanolic extract of the root bark of R. sambuci-
folia was fractionated to provide twenty-four compounds.
Compound 1 was obtained as white amorphous pow-
der from acetone and fluoresced under UV lamp. The FAB-
MS spectrum exhibited a molecular ion peak at m/z 513

76 J. Chin. Chem. Soc., Vol. 54, No. 1, 2007
Hu et al.
matic protons) flanked the acetyl function (dH 2.48, 3H, s),
1
11,16-diketo-apian-8,14(15)-dien-(20,6)-olide (6)13], two
catechins [(+)-catechin (7),14 procyanidin B-2 monogallate
(8)15], four lignans [(7S,8R)-2,4-dihydroxy-7,3¢-epoxy-
8,4¢-oxyneolign-7¢-ene (9),16 (7S,8S)-2,4-dihydroxy-7,3¢-
epoxy-8,4¢-oxyneolign-7¢-ene (10),16 (7S,8R)-2,4-dihy-
droxy-7,3¢-epoxy-8,4¢-oxyneolign-7¢-ine (11),16 (7S,8S)-
2,4-dihydroxy-7,3¢-epoxy-8,4¢-oxyneolign-7¢-ine (12)16],
two benzenoids [p-hydroxybenzoic acid (13),17 methyl par-
aben (14)18], two isocoumarins [bergenin (15),19 7-meth-
oxy bergenin (16)20], two steroids [ergosterol (17),21,22
stigmast-5-en-3b-ol (18)20,23], six monoterpene glycosides
[(E)-3,7-dimethyl-1-O-[a-L-rhamnopyranosyl-(1®6)-b-
D-glucopyranosyl]-oct-2-en-7-ol (19),24 (E)-3,7-dimethyl-
1-O-[a-L-arabinofuranosyl-(1®6)-b-D-glucopyranosyl]-
oct-2-en-7-ol (20),25 geranyl-1-O-a-L-arabinofuranosyl-
(1®6)-b-D-glucopyranoside (21),26 geranyl-1-O-a-L-
rhamnopyranosyl-(1®6)-b-D-glucopyranoside (22),26
geranyl-1-O-b-D-xylopyranosyl-(1®6)-b-D-glucopyrano-
side (23),27 geranyl-1-O-a-L-arabinopyranosyl-(1®6)-b-
D-glucopyranoside (24)28].
indicating 8 position of 1 is substituted. The H and 13C
NMR spectra of the aglycone showed a very close similar-
ity with those of acetovanillochromene,7 the only differ-
ences being the presence of the signals for the HO-8 of the
aglycone instead of the signals for the MeO-8 of acetova-
nillochromene. Thus, the aglycone moiety of 1 was pre-
sumed to be demethylacetovanillochromene previously re-
ported from Tithonia diversifolia.8
The acid hydrolysis of compound 1 gave an aglycone
and two sugars identified as D-glucose and D-apiose on the
basis of co-TLC with authentic sample, showing the pres-
ence of D-glucose and D-apiose unit. In addition, it was
also deduced from the FAB-MS spectral observation of 381
[M+H-132]+ and 219 [M+H-132-162]+ fragment ions, aris-
ing from the elimination of a glucose and an apiose unit,
further indicating the apiose was terminal sugars, and glu-
1
cose was attached to aglycone. The H NMR spectrum
showed signals at dH 5.28 (1H, d, J = 2.1 Hz, H-1², api.
anomeric H) and 5.07 (1H, d, J = 7.8 Hz, H-1¢, glu.
anomeric H) due to anomeric protons of two sugars. The
configuration of the glucopyranosyl unit was deduced to be
b from the J value (7.8 Hz) of the anomeric proton, and of
the apiofuranosyl unit to be b by compairing the 13C NMR
spectra data of 1 with those of a-D-(dC 104.5) and b-D-
apiofuranosides (dC 111.5), respectively.9 The HMBC ex-
periment of 1 showed long-range correlations (Table 1) be-
tween the H-1² (dH 5.28) of apiose with the C-6¢ (dC 68.2)
of glucose as well as between the H-6¢ (dH 3.72) of glucose
with the C-1² (dC 111.1) of apiose, suggesting the linkage
of apiose-(1®6)-glucose. Additionally, the HMBC corre-
lation between the H-1¢ (dH 5.07) of glucose and the C-8 (dC
146.7) suggested that the disaccharide chain was located at
C-8 of the aglycone. Easy hydrolysis showed that the
glycoside linkage was C-O-C type, and the 13C NMR data
also support this conclusion.
These known compounds were identified by compar-
ison of relevant data (UV, IR, NMR, MS) with the literature
values or with authentic samples.
In addition to compound 1, two known compounds 2
and 3 have been isolated for the first time from the Rodgersia
species.
EXPERIMENTAL SECTION
General Experimental Procedures
Melting points were determined on an XT-4A melt-
ing point apparatus and are uncorrected; UV spectra on a
Shimadzu UV-300 (double beam) spectrophotometer; IR
spectra (KBr disks) were obtained on an Alpha-Centari
FT-TR spectrometer; 1H and 13C NMR spectra were scan-
ned on a Bruker AM-500 spectrometer operating at 500 and
125 MHz (chemical shifts in d downfield from TMS inter-
nal standard), and mass spectra on a VG Auto Spec-3000
spectrometer; Elemental analysis was carried out on a 1106
elemental analysis apparatus. Silica gel (100-200, 200-300
mesh) used for column chromatography and GF254 for TLC
were from Qingdao Marine Chemical Factory, China. Gel
sephadex LH-20 and RP-18 were the products of the Phar-
macia AB Laboratory Separation Division, Uppsala, Swe-
den, and Merck Company, Germany, respectively. The
Based on the above observations, compound 1 was
determined as 2,2-dimethyl-2H-(8-hydroxyl-6-acetyl)-[2,3-
b] pyran-8-O-b-D-apiofuranosyl-(1®6)-b-D-glucopyrano-
side.
The known compounds included three flavonoids
[5,4¢-dihydroxy-7,8-[(3²,4²-dihydro-3²,4²-dihydroxy)-2²,
2²-dimethylpyran]-flavone (2),10 5,4¢-dihydroxy-3¢,5¢-di-
methoxy-6,7-(2²,2²-dimethylpyran)-flavone (3),11 quer-
cetin (4)12], two diterpenoids [14a-hydroxy-7a-ethoxy-
11,16-diketo-apian-8-en-(20,6)-olide (5),13 7a-hydroxy-

Chemical Constituents from R. sambucifolia
J. Chin. Chem. Soc., Vol. 54, No. 1, 2007 77
Table 1. 1H and 13C NMR data of compounds 1 (500 MHz & 125 Hz, JHz, acetone-d6, TMS)
Position
dH
dC
DEPT
HMBC
2
76.8
125.8
115.8
120.9
131.2
116.7
146.7
158.9
105.7
196.8
25.7
C
6.62, 5.64, 1.46
6.62
3
5.64 (1H, d, J = 10.0 Hz)
6.62 (1H, d, J = 10.0 Hz)
7.42 (1H, d, J = 2.0 Hz)
CH
CH
CH
C
4
5.64, 7.42
6.62, 7.42, 7.21
7.42, 7.21
7.42
5
6
7
7.21 (1H, d, J = 2.0 Hz)
CH
C
8
5.07
9
C
7.21
10
11
12
Me
Glucose
1¢
C
6.62, 7.42
7.21, 2.48
C
2.48 (3H, s)
1.46 (6H, s)
CH3
CH3
25.7
5.07 (1H, d, J = 7.8 Hz)
104.6
75.4
78.1
71.2
77.2
68.2
CH
CH
CH
CH
CH
CH2
2¢
3.31 (1H, dd, J = 9.0, 7.8 Hz)
3.36 (1H, dd, J = 9.0, 8.3 Hz)
3.28 (1H, dd, J = 9.9, 8.3 Hz)
3.10 (1H, ddd, J = 9.9, 5.8, 1.6 Hz)
3.48 (1H, dd, J = 11.3, 5.8 Hz)
3.72 (1H, dd, J = 11.3, 1.6 Hz)
3¢
4¢
5¢
6¢
5.28
Apiose
1²
5.28 (1H, d, J = 2.1 Hz)
3.88 (1H, d, J = 2.1 Hz)
111.1
77.2
80.1
75.5
64.9
CH
CH
C
3.58, 3.72
2²
3²
4²
3.65 (1H, d, J = 9.2 Hz), 3.91 (1H, d, J = 9.2 Hz)
3.52 (2H, s)
CH2
CH2
5²
spots were visualized by UV (254 nm) and EtOH-H2SO4.
and A11 were repeatedly rechromatographed over silica gel
and purified by recrystallization or preparative TLC to af-
ford 2 (18.5 mg), 3 (12.3 mg), 4 (25.0 mg), 5 (18.5 mg) and
6 (8.2 mg), respectively. Fraction A14 was fractionated over
a silica gel column with CHCl3-MeOH gradient to give 8
(9.5 mg), 13 (18.6 mg), and 14 (12.8 mg), respectively. The
H2O-soluble fraction was partitioned with EtOAc, then
with n-BuOH to give EtOAc fraction (fraction B, 75 g), the
n-BuOH-soluble fraction (fraction C, 35 g) and the H2O-
soluble fraction. Fraction B was chromatographed over sil-
ica gel column, eluting with CH2Cl2, and then polarity was
gradually increased with EtOAc to obtain 13 fractions (B1-
B18). From fractions B1-B4, rechromatographed on silica
gel with CHCl3-MeOH (5:1-1:5, V/V) as eluent and pre-
parative TLC, to yield 7 (10.0 mg), 9 (11.2 mg), 10 (8.4
mg), 11 (15.6 mg), and 12 (12.7 mg), respectively. Then
from fraction B5-B10, through rechromatographed on silica
gel with EtOAc-MeOH (5:1-1:10, V/V) as eluent, prepara-
tive TLC and recrystallization, respectively, 15 (21.0 mg),
16 (13.2 mg), 17 (12.0 mg) and 18 (11.5 mg) were obtained.
Fraction B11-B18 rechromatographed on silica gel, eluted
Plant Material
The root bark of R. sambucifolia was collected from
the Dali area of Yunnan province of China in August 2003,
and were identified by Prof. Yun-Shan Lian, Department of
Biology. A voucher specimen (No. 100813) was deposited
at the Herbarium of the Botany Department, Northwest
Normal University, Lanzhou, 730070, China.
Extraction and Isolation
The fresh and shade-dried root bark (5 kg) was chip-
ped, extracted three times with MeOH (15 L ´ 7 d each) at
room temperature, and concentrated in vacuo. The MeOH
extract (252 g) was partitioned between CHCl3-H2O (1:1,
V/V) to divide into a CH3Cl-soluble fraction (fraction A,
80 g) and an H2O-soluble fraction. Fraction A was sub-
jected to silica gel column chromatography and eluated
with n-hexane, CHCl3, CHCl3-Me2CO (5:1-1:5, V/V),
Me2CO and Me2CO-MeOH (4:1-1:10, V/V) gradient elu-
tion to give 16 fractions (A1-A16). Fractions A2, A5, A8, A10

78 J. Chin. Chem. Soc., Vol. 54, No. 1, 2007
Hu et al.

Chemical Constituents from R. sambucifolia
J. Chin. Chem. Soc., Vol. 54, No. 1, 2007 79
with CHCl3-MeOH (5:1, V/V), and by gradually increase
the polarity with MeOH and preparative TLC, afforded 1
(5.6 mg), 19 (8.5 mg), 20 (11.6 mg), 21 (7.5 mg), 22 (12.8
mg), 23 (15.4 mg) and 24 (10.2 mg).
MHz) dH: 7.98 (2H, d, J = 8.1 Hz, H-2¢/6¢), 7.02 (2H, d, J =
8.1 Hz, H-3¢/5¢), 6.84 (1H, s, H-6), 6.31 (1H, s, H-3), 4.75
(1H, d, J = 4.8 Hz, H-4²), 4.36 (1H, d, J = 4.8 Hz, H-3²),
1.28 (3H, s, Me-2²), 1.16 (3H, s, Me-2²); 13C NMR (ace-
tone-d6, 125 MHz) dC: 162.8 (C-2, C), 103.7 (C-3, CH),
182.9 (C-4, C), 163.7 (C-5, C), 100.3 (C-6, CH), 165.8
(C-7, C), 104.2 (C-8, C), 152.9 (C-9, C), 108.1 (C-10, C),
120.9 (C-1¢, C), 128.4 (C-2¢, CH), 116.4 (C-3¢, CH), 161.8
(C-4¢, C), 115.9 (C-5¢, CH), 128.4 (C-6¢, CH), 69.9 (C-2²,
C), 94.2 (C-3², CH), 70.5 (C-4², CH), 25.5 (CH3-2², CH3),
25.2 (CH3-2², CH3). EI-MS: m/z 370 [M]+, 334, 294, 216,
118. (Found: C, 64.78; H, 4,98. Calcd for C20H18O7: C,
64.85; H, 4.90).
2,2-Dimethyl-2H-(8-hydroxy-6-acetyl)-[2,3-b] pyran-8-
O-b-D-apiofuranosyl-(1®6)-b-D-glucopyranoside 1
White amorphous powder (acetone), mp. 218-220 °C;
UV l mMaexOH (nm): 248 and 312; IR nKmBaxr (cm-1): 3018, 1658,
1610, 1595, 1485, 1384, 1370, 1270, 1126, 1088, 1070,
1036, 880, 870; HR-FAB-MS: m/z 512.1904 (M+, calcd for
C24H32O12, 512.1894); FAB-MS: m/z 513 [M+H]+, 381
1
[M+H-132]+ and 219 [M+H-132-162]+; for H and 13C
NMR data, see Table 1.
5,4¢-dihydroxy-3¢,5¢-dimethoxy-6,7-(2²,2²-dimethylpy-
ran)-flavone 3
Acid hydrolysis of compound 1
Compound 1 (8 mg) was treated with 50% MeOH-
HCl (5 mL) under reflux at 95 °C for 1.5 hr in a water bath.
The reaction mixture was cooled, then concentrated under
pressure to give a syrup which was partitioned between
EtOAc/H2O. The aqueous layer was neutralized with NH3·
H2O and concentrated in vacuo. The sugars were identified
by co-TLC (GF254 silica gel plate) with authentic samples
using a solvent system [CHCl3-MeOH-H2O (70:30:3)],
visualization by 0.9% C6H6NH2-C2H2O4 spray and then
heating at 100 °C for 5 min; the spot of glucose displayed
brown (Rf: 0.26), and apiose showed red (Rf: 0.64). The
EtOAc extract was dried over anhydrous Na2SO4, and re-
crystallized from (CHCl3-Me2CO) to give aglycone of 1
(3 mg). Aglycone of 1 was colourless crystals (CHCl3/
Me2CO), mp. 140-142 °C (lit.8 142 °C); UV l mMaexOH (nm):
Yellow prisms (CHCl3), mp. 230-232 °C; UV l mMaexOH
(nm): 246, 297, 312, 358; 1H NMR (CDCl3, 500 MHz) dH:
6.54 (1H, s, H-3), 6.43 (1H, s, H-8), 7.05 (2H, s, H-2¢/6¢),
5.60 (1H, d, J = 9.8 Hz, H-3²), 6.68 (1H, d, J = 9.8 Hz,
H-4²), 4.01 (6H, s, MeO-3¢/5¢), 1.45 (6H, s, Me-2²), 5.98
(1H, s, HO-4¢), 12.98 (1H, s, HO-5); 13C NMR (CDCl3, 125
MHz) dC: 163.5 (C-2, C), 104.1 (C-3, CH), 182.3 (C-4, C),
156.1 (C-5, C), 105.1 (C-6, C), 158.9 (C-7, C), 98.5 (C-8,
CH), 156.9 (C-9, C), 105.7 (C-10, C), 122.1 (C-1¢, C), 112.4
(C-2¢, CH), 148.9 (C-3¢, C), 146.1 (C-4¢, C), 148.7 (C-5¢,
C), 103.8 (C-6¢, CH), 76.5 (C-2², C), 129.7 (C-3², CH),
115.2 (C-4², CH), 28.4 (CH3-2², CH3), 56.7 (CH3O-3¢/5¢,
CH3). EI-MS: m/z 396 [M]+, 381, 365, 203, 69. (Found: C,
66.58; H, 5.12. Calcd for C22H20O7: C, 66.65; H, 5.09).
246 and 310; IR n (cm-1): 3246, 1660, 1608, 1483, 1384,
KBr
max
1
1372, 1269, 1124, 880, 870; H NMR (acetone-d6, 500
ACKNOWLEDGEMENTS
MHz) dH: 1.45 (6H, s, CH3 × 2), 2.50 (3H, s, H-12), 5.64
(1H, d, J = 10.0 Hz, H-3), 6.58 (1H, d, J = 10.0 Hz, H-4),
7.26 (1H, d, J = 2.0 Hz, H-7), 7.45 (1H, d, J = 2.0 Hz, H-5);
13C NMR (acetone-d6, 125 MHz) dC: 77.2 (C-2, C), 126.7
(C-3, CH), 115.9 (C-4, CH), 121.7 (C-5, CH), 130.6 (C-6,
C), 115.1 (C-7, CH), 152.2 (C-8, C), 153.9 (C-9, C), 105.9
(C-10, C), 194.9 (C-11, C), 26.4 (C-12, CH3), 27.1 (CH3 ´ 2).
EI-MS: m/z 218 [M]+, 203, 175, 160, 157, 129, 94. (Found:
C, 71.42; H, 6.56. calcd for C13H14O3: C, 71.53; H, 6.47).
We are grateful to Prof. Yun-Shan Lian for identify-
ing the plant and Prof. Shang-zhen Zheng for kind help
with our work. The work was kindly supported by the Edu-
cation Department, Foundation of Gansu Province (Grant
No. 2003039-04), China.
Received February 9, 2006.
5,4¢-dihydroxy-7,8-[(3²,4²-dihydro-3²,4²-dihydroxy)-
2²,2²-dimethylpyran]-flavone 2
REFERENCES
White amorphous powder (acetone), mp. 234-236 °C;
UV l mMaexOH (nm): 268, 315, 340; 1H NMR (acetone-d6, 500
1. Pan, J.-T. Acta Phytotax Sin. 1994, 32, 316.

80 J. Chin. Chem. Soc., Vol. 54, No. 1, 2007
Hu et al.
2. Wu, C.-Y. Xinhua Bencao Gangyao. Shanghai Science &
Technology Press: Shanghai, 1990; pp 77-83.
1994, 35, 4.
15. Yuan, K.; Liu, Y.-Z.; Wang, L.; Wang, Z.-H.; Ji, C.-R.; Wu,
L.-L.; Tahashi, Y.; Takuo, O. Henan Science 1994, 12, 38.
16. Chin, Y.-W.; Kim, J. W. Tetrahedron Lett. 2004, 45, 339.
17. Cheng, M.-J.; Tsai, I.-L.; Chen, I.-S. J. Chin. Chem. Soc.
2001, 48, 235.
3. Liu, Y.-Z.; Yuan, K.; Wang, L.; Ji, C.-R. Nat. Prod. Res. &
Dev. 1995, 7, 1.
4. Jiangsu New Medical College. Dictionary of Traditional
Chinese Drugs. Science and Technology Press: Shanghai,
1985; pp 1342-1333.
18. Chen, C.-Y.; Wu, Y.-C. J. Chin. Chem. Soc. 2001, 48, 1203.
19. Farboodniary Jahromi, M.-A. Phytotherapy Res. 1992, 6,
180.
5. Zheng, S.-Z.; An, H.-G.; Shen, T.; Shen, X.-W. Indian J.
Chem. 2002, 41B, 228.
6. Jackman, S.-M. Progress in the Chemistry of Organic Natu-
ral Products; edited by L. Zechmeister, Smithsonian Institu-
tion Press: New York, 1965; pp 315-325.
20. Shen, X.-W.; Zheng, S.-Z.; Fu, Z.-S.; Chen, H. Chem. J.
Chin.Univ. 1987, 8, 528.
21. Cheng, M.-J.; Tsai, I.-L.; Chen, I.-S. J. Chin. Chem. Soc.
2003, 50, 1241.
7. Taylor, D.-R.; Wright, J.-A. Phytochemistry 1971, 10, 1665.
8. Shamsuddin, K.-M.; Musharraf, M.-A.; Zobairi, M.-O.;
Nazakat, A. Indian J. Chem. 2001, 40B, 825.
22. Li, J.-X.; Li,-J.; Xu, L.-Z. Chin. Pharm. J. 2003, 38, 499.
23. Chang, Y.-C.; Chang, F.-R.; Wu, Y.-C. J. Chin. Chem. Soc.
2000, 47, 373.
9. Kitagawa, I.; Hori, K.; Sakagami, M.; Hashiuchi, F.;
Yoshikawa, M.; Ren, J. Chem. Pharm. Bull. 1993, 41, 1350.
10. Kassem, M.; Mosharrafa, S.-A.; Saleh, N.-A.-M.; Abdel-
Wahab, S.-M. Fitoterapia 2000, 71, 649.
24. Ji, C.-J.; Tan, N.-H.; Fu, J.; Zhang, Y.-M.; He, M. Acta Bot.
Yunnan. 2004, 26, 465.
25. Marinos, V.-A.; Tate, M.-E.; Williams, P.-J. J. Agric. Food
Chem. 1994, 42, 2486.
11. Jose, P.-I.-D.; Alberto, C.-A.; Gaspar, D.-M.; Mara, S.-P.-A.;
Adolfo, H.-M. Phytochemistry 1999, 52, 1705.
12. Tsai, F.-Y.; Lee, S.-S.; Chen, I.-S. J. Chin. Chem. Soc. 1995,
42, 101.
26. Williams, P.-J.; Strauss, C.-R.; Wilson, B.; Massy-Westropp,
R.-A. Phytochemistry 1982, 21, 2013.
27. Guo, W.-F.; Sakata, K.; Watanabe, N.; Nakajima, R.; Yagi,
A.; Ina, K.; Luo, S.-J. Phytochemistry 1993, 33, 1373.
28. Yoshikawa, K.; Nagai, M.; Wakabayashi, M.; Arihara, S.
Phytochemistry 1993, 34, 1431.
13. Zheng, S.-Z.; Yang, C.-X.; Fu, Z.-S.; Shen, X.-W. Planta
Med. 1998, 64, 579.
14. Bae, Y.; Burger, J.-F.-W.; Steynberg, J.-P. Phytochemistry