全 文 ：Two New Xanthones from the Stems of Securidaca inappendiculata
YANG Xue_Dong1＊ , XU Li_Zhen2＊＊ , YANG Shi_Lin2
(1.Department of Chemistry , Tsinghua University , Bei jing 100084 , China;
2.Institute of Medicinal Plant Development , Peking Union Medical College and Chinese Academy of Medical Sciences , Bei jing 100094 , China)
Abstract:　Two new antioxidant compounds , securixanthones C(1)and D(2)were isolated from the stems
of Securidaca inappendiculata Hassk.The structures of the two new compounds were established on the basis of
EI_MS , 1D_NMR and 2D_NMR , UV , and IR experiments.
Key words:　Securidaca inappendiculata;Polygalaceae;securixanthone C;securixanthone D
　　The genus Securidaca (Polygalaceae)consists of
about 43 species growing mainly in tropical America , a
few of them distribute in tropical Asia and Africa(Delec-
tis Florae Reipublicae Popularis Sinicae Agendae
Academiae Sinicae Edita , 1997).As a traditional Chinese
herbal medicine , Securidaca inappendiculata is used as an
anti_inflammatory , anti_bacterial and anti_rheumatism a-
gent(Jiangsu Institute of Botany , 1988).
Our previous studies on this species have revealed
the presence of xanthones (Yang et al , 2001a;2002a;
2002b), organic acids (Yang et al , 2001b), sucrose
derivatives(Yang et al , 2003), hemiterpenic acid glyco-
sides(Yang et al , 2002c), and other compounds(Yang
et al , 2002c;2002d).Reinvestigation of this plant has
now led to the isolation of two new xanthones , securixan-
thone C (1), and securixanthone D(2).In this study ,
we report the isolation and structure elucidation of these
two new xanthones from the ethyl acetate fraction of the
ethanolic extract of the stems of S .inappendiculata.The
antioxidative activity of these compounds has been tested.
1　Results and Discussion
Compound 1 , obtained as yellow needles(MeOH),
mp 236 ℃, had a molecular formula of C14H10O6 estab-
lished by HREI_MS (m/ z 274.048 6 [M] + , calcd.
274.047 7).The UV spectrum of 1 exhibited characteris-
tic absorption bands of a xanthone (λMeOHmax 230 , 260 ,
310 , 378 nm)and a bathochromic shift induced by addi-
tion of NaOAc , suggesting the presence of a free hydroxyl
group at C_6 or C_3.The lack of a di_ortho_hydroxyl
group was evident by the absence of a shift after the addi-
tion of NaOAc and H3BO3(Harborne , 1998).The 1H-
NMR spectrum showed a chelated OH (δ12.63)and two
OH(δ10.92 , 10.00)at other positions , one aromatic
methoxyl(δ3.81), a three_proton spin system(δ7.55 ,
7.42 and 7.30;J =9.0 and 3.0 Hz)and a singlet(δ
6.28).In the 13C_NMR spectrum , the signal at δ60.8
was indicative of one di_ortho_substituted methoxyl group(Frahm and Hambloch , 1982).The positions of the sub-
stituents were confirmed unambiguously by a NOESY ex-
periment (Fig.1).Those hydroxyl groups were at the
C_1 , C_3 and C_7 positions and the methoxyl group at the
C_4 position.From the above data , 1 was determined to
be 1 , 3 , 7_trihydroxy_4_methoxyxanthone , named securix-
anthone C.
Compound 2 was obtained as fine orange needles(MeOH), mp 202-204 ℃.The molecular formula was
assigned as C15H12O5 on the basis of HREI_MS (m/ z
272.070 0 [ M] + , calcd.for C15H12O5 , 272.068 5).
The UV spectrum (in MeOH)of 2 showed characteristic
absorption bands of a xanthone at 237 , 260 , 311 and 380
nm.The presence of a free hydroxyl group at C_6 or C_3
was excluded based on the lack of any change in the UV
spectrum upon addition of NaOAc (Harborne , 1998).
The
1
H_NMR spectrum displayed resonances of two aro-
matic methoxyls (δ3.80 and 3.86), a hydroxyl (δ
9.88), a three_proton spin system (δ7.44 , 7.42 and
7.25;J =9.0 and 3.0 Hz)and an AB system(δ7.60
and 7.35)of two protons ortho_coupled (J =9.2 Hz).
The
13
C_NMR spectrum indicated that there were two aro-
matic methoxyls at δ60.9 and 56.7 and there were no
substituted groups at C_1 or C_8 position according to the
carbonyl carbon shift (175.10)(Philip et al , 1977).
The positions of the substituents were confirmed by the
Fig.1.　NOE interactions of compounds 1 and 2.
Received:2002-08-26　Accepted:2002-12-11
＊Postdoctor of Tsinghua University.E_mail:.
＊＊ Author for correspondence.E_mail:.
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Acta Botanica Sinica　2003 , 45(3):365-368 http://www.chineseplantscience.com
NOESY experiment(Fig.1).Therefore , the structure of
2 was concluded to be 7_hydroxy_3 ,4_dimethoxyxanthone ,
named securixanthone D.
In order to verify the antioxidant activity , the radical
scavenger capacity of the tested samples were detected in
the TLC stained with DPPH , a stable free radical , which
produced a violet background on silica layer.For the
rapid screening of radical scavenger capacity , each dilut-
ed sample was applied as a dot on a TLC layer that was
later developed and sprayed with DPPH solution.The ap-
pearance of yellow color in the spots has a potential value
for the indirect evaluation of the radical scavenger capaci-
ty of the samples(Soler_Rivas et al , 2000).The method
is typically based on the inhibition of the accumulation of
oxidized products , since the generation of free radicals is
inhibited by the addition of antioxidants and the end point
by scavenging the free radical.It is similar to the result of
DPPH spectrophotometric assay (Choi et al , 2002).
Compounds 1 and 2 gave a positive reaction with
DPPH , they all showed stronger intensities of yellow spots
up to dilutions of 50 μg/mL.As reference compound ,
quercetin showed strong intensities of white_yellow spots
detecting up to 50 μg/mL dilution.During the assay , the
reaction was very stable , producing reliable spots in the
repeated tests because DPPH containing an odd electron
gave a strong absorption at 518 nm in visible spectrum.
As this electron became paired off in the presence of a
free radical scavenger , the absorption faded and the re-
sulting decolorization was stoichiometric with respect to
the number of electrons taken up(Brand_Williams et al ,
1995).
2　Experimental
2.1　General experimental procedures
Melting points were determined on a Fisher Johns
apparatus and uncorrected.UV spectra were measured on
a philips PYE Unican Pu8800 spectrophotometer.IR
spectra were obtained in KBr disks on a Perkin_Elmer
983G spectrophotometer.1D_ and 2D_NMR spectra were
recorded on a Bruker ARX 400 spectrometer.The
FABMS (positive mode)were recorded in a Zabspec E
mass spectrometer.EI_MS were obtained on a VG ZAB_2f
mass spectrometer.TLC and HPTLC were employed by
precoated silica gel plates (Qingdao Haiyang) and
polyamide plates(Zhejiang Huangyan).For column chro-
matography , silica gel (Qingdao Haiyang)and Sephadex
LH 20(Pharmacia)were used.The medium pressure liq-
uid chromatography (MPLC)was performed on a system
equipped with a Bǜchi pump B_688 , Bǜchi B_684 Frac-
tion collector , UVILOG_5IIIA UV_Detector , Bǜchi
columns and precolumns , with the stationary phase silica
gel 60 (15-40 μm , Qingdao Haiyang)and polyamide(>200 mesh , Hunan Lixian Yizhong).
2.2　Plant material
The stems of Securidaca inappendiculata Hassk were
collected in Yunnan Province of China and identified by
Prof.LIAN Wen_Yan (Institute of Medicinal Plant
Development , Peking Union Medical College (PUMC)
and Chinese Academy of Medical Sciences(CAMS))and
Prof.WANG Hong (Menglun Botanical Garden , Yunnan
Province).A voucher specimen(YS_9801)was deposited
in the New Drug Research and Development Center of In-
stitute of Medicinal Plant Development , PUMC and
CAMS.
2.3　Extraction and isolation
The dried ground stems(10 kg)of the plant material
were extracted with 95%EtOH(30 L×3 , 2 h each)un-
der reflux.The EtOH extract(750 g)was fractionated by
solvent reflux in a Soxhlet apparatus (silica gel as ab-
sorbent)into CHCl3 , EtOAc , Me2CO and MeOH parts.
The EtOAc part (31 g)was chromatographed on MPLC(silica gel , 200-300 mesh)and eluted with a gradient
of Me2CO in CHCl3 (100∶0-40∶60)to give 36 frac-
tions.Fractions 1-3(100∶0-96∶4)were purified by
polyamide column chromatography eluted with CHCl3_
MeOH(1∶0-0∶1 , gradient)and Sephadex LH_20 to
give compound 1(10 mg).The CHCl3 soluble(10.5 g)
was subjected to MPLC (silica gel , 200 -300 mesh)
eluted with a gradient of Me2CO in petroleum ether(95∶5-50∶50)to give 18 main fractions.Fraction 16(65∶35)
was purified by polyamide CC eluted with CHCl3–-MeOH(1∶0-0∶1 , gradient)and Sephadex LH_20 to give com-
pound 2(8 mg).
2.4　Identification
Compound 1 , obtained as yellow needles from
MeOH , mp 186-188 ℃;showed negative reaction with
Mg_HCl , dark purple fluorescence under UV light (on
polyamide film)and dark green color with FeCl3.HREI_
MS [ M] + m/ z:274.048 5 (calcd.for C14H10O6 ,
274.047 7).UV (MeOH)λmax:230 , 260 , 310 , 378
nm;+NaOAc:268 , 338 , 390 nm;+NaOAc +
H3BO3:259 , 310 , 378 nm.IR (KBr)νmax:3 520 ,
3 320 , 1 650 , 1 635 , 1 600 , 1 580 , 1 480 cm-1.EI-
MS m/ z:274 (M+ , 30), 259 (35), 245 (10), 231
(100).1H-NMR and 13C_NMR spectral data are shown in
Table 1.
Compound 2 , obtained as yellow needles from
MeOH , mp 194-196 ℃;showed negative reaction with
Mg_HCl , dark purple fluorescence under UV light (on
polyamide film)and dark green color with FeCl3.HREI_
MS [ M] + m/ z:272.068 9 (calcd.for C15H12O5 ,
272.068 5).UV (MeOH)λmax:237 , 260 , 311 , 380
nm;+NaOAc:260 (sh), 311 (sh), 380 nm;+NaOAc+H3BO3:260 , 311 , 380 nm.IR(KBr)νmax:
3 420 , 1 660 , 1 610 , 1 480 , 1 580 cm-1.EI-MS m/z:
272(M+ , 85), 257(100), 243(50), 229(80).1H-
NMR and
13
C_NMR spectral data are shown in Table 1.
2.5　Rapid screening of antioxidative activity(Cuen-
det et al , 1997)
Drops(3 μL)of each sample were carefully loaded
on a 20×20 TLC layer in order of decreasing concentra-
tion along the baseline and allowed to dry.After develop-
ing with chloroform∶methanol(98∶2 , V/V)and drying ,
TLC plates were sprayed with a 0.2% DPPH (1 ,1_
366　 植物学报　Acta Botanica Sinica　Vol.45　No.3　2003
Table 1　13C_ and 1H-NMR data of compounds 1 and 2(100/ 400
MHz , in DMSO_d6 , J in Hz)
C/H 1
13C 1H
2
13C 1H
1 158.5 122.0 7.60 d(9.2)
2 97.8 6.28 s 115.8 7.35 d(9.2)
3 149.6 150.5
4 127.3 148.4
4a 148.9 147.4
4b 157.6 148.5
5 119.1 7.55 d(9.0) 118.8 7.44 d(9.0)
6 124.5 7.30 dd(9.0 , 3.0) 124.0 7.25 dd(9.0 , 3.0)
7 153.9 153.6
8 108.0 7.42 d(3.0) 108.5 7.42 d(3.0)
8a 120.2 120.6
8b 101.8 113.2
C O 179.9 175.1
MeO_3 56.7 3.86 s
MeO_4 60.8 3.80 s 60.9 3.80 s
HO_1 12.63
HO_3 10.92
HO_7 10.00 9.88
diphenyl_2_picrylhydrazyl)solution in MeOH.The plates
were examined 30 min after spraying.Active compounds
appeared as yellow spots against a purple background.
The intensity of the yellow color depends upon the amount
and nature of radical scavenger present in the sample.
Quercetin was used as reference compound.
Acknowledgements:The authors express their gratitude
to Prof.CONG Pu_Zhu for his helpful suggestions for the
structure elucidation by MS;Prof.L Mu_Jian and PAN
Jing_Qi (Analysis Center , College of Chemistry and
Molecular Engineering of Peking University)for obtaining
the NMR and NOESY;Prof.LI Li_Jun(Institute of Ma-
teria Medica , PUMC and CAMS)for recording the EI_
MS;Mr.WU Sheng_Ming (Academy of Military Medical
Sciences)for HREI_MS measurements.
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(Managing editor:WANG Wei)
YANG Xue_Dong et al:Two New Xanthones from the Stems of Securidaca inappendiculata 367　
蝉翼藤茎中的两个新口山酮成分
杨学东1＊　徐丽珍2＊＊　杨世林2
(1.清华大学化学系 , 北京 100084;2.中国医学科学院 、中国协和医科大学药用植物研究所 , 北京 100094)
摘要:　首次从蝉翼藤(Securidaca inappendiculata Hassk)茎乙醇提取物的乙酸乙酯部分分离到两个新的具有抗氧化
作用的口山酮类化合物 securixanthone C (1)和 securixanthone D(2)。这两个新化合物的结构是通过波谱方法(1D_
NMR和 2D_NMR、 EI_MS 、 UV 和 IR)鉴定的。
关键词:　蝉翼藤;远志科;securixanthone C;securixanthone D
中图分类号:R914　　　文献标识码:A　　　文章编号:0577-7496(2003)03-0365-04
收稿日期:2002-08-26　接收日期:2002-12-11
＊清华大学博士后。E_mail:。
＊＊通讯作者。E_mai l:。
(责任编辑:王　葳)
368　 植物学报　Acta Botanica Sinica　Vol.45　No.3　2003