COUMARINS FROM CYNANCHUM ACUTUM

A. El-Demerdash, A. M. Dawidar, E. M. Keshk and M. Abdel-Mogib1

(Received November 2008; Accepted March 2009

ABSTRACT

From the aerial parts of Cynanchum acutum L. several compounds have been
isolated including the simple coumarins scopoletin and scoparone. The isolated
compounds were identified on the basis of spectral methods (IR, UV, 1H NMR, and
GC/MS). This is the first report of coumarins from the genus Cynanchum.

Key words: Asclepiadaceae, Cynanchum acutum, coumarins, scopoletin, scopa-

rone.

RESUMEN

De las partes aéreas de Cynanchum acutum L. se aislaron varios compuestos, entre

ellos la escopoletina y escoparona. Los compuestos aislados se identificaron por
métodos espectroscópicos (IR, UV, 1H NMR, y GC/MS). Este es el primer reporte
de cumarinas del genero Cynanchum.

INTRODUCTION The phytochemical investigation of the

genus Cynanchum revealed the isolation
Family Asclepiadaceae comprises many and characterization of many classes of
medicinal parts with a wide range of thera- natural products including steroidal gly-
peutic activities. The dried whole plant of cosides (Liu et al., 2007), carbohydrates
Cynanchum arnottianum has been used in (Yi-Bin et al., 2004), alkaloids (Tian-Ying
India and tropical America as insecticide et al., 2001), phenolic compounds (Lou et
and parasiticide (Lewis, H.W. and Lewis., al., 1993), and triterpenes (Konda et al.,
1977). C. atratum dried whole plant has 1990).
been used as antifebrile and diuretic in Cynanchum acutum L. (Asclepiadaceae)
China (Zhang et al., 1985). The dried whole is a wild perennial herb commonly distri-
plant of C. paniculatum has been used as buted in Egypt and known as olliq, modeid,
anodyne and for the therapy of chronic or libbein (Tackholm, 1974). The phyto-
tracheitis in China (Sakuma et al., 1968). chemical investigation of this species led
C. wilfordi is used as a substitute for the to the isolation of β-sitosterol, lupeol, lupyl
tonic crude drug “Ka-Shu-Uh” in Korea acetate, and α-amyrin (Halim et al.,1990),
(Tsukamoto et al., 1985). sarcostine, quercetin and quercetin 3-O-β-

Chemistry Department, Faculty of Science, Mansoura University, Mansoura-35516, Mansoura, Egypt.

1
Corresponding author: E-mail mamdouh_m@mans.edu.eg, Tel.: +2 0502242388

65
66 A. El-Demerdash, A.M. Dawidar, E.M. Keshk and M. Abdel-Mogib

D-galactoside (El Sayed et al.,1994), as well Plant material

as four flavonoid glycosides: quercetin di-
O-hexoside, quercetin 3-O-rhamnosyl(1→ C. acutum L. (Asclepiadaceae) was collected
2)glycoside, quercetin 3-O-galactoside, and from New Damitta, Egypt, in May 2005 by
quercetin 3-O-xyloside (Heneidak et al., the forth author and identified by Prof. Dr.
2006). In this article, we present the isola- Ibrahim Mashaly, Prof. of Plant Ecology,
tion of two simple coumarins, in addition Botany Department, Faculty of Science,
to other compounds from C. acutum. This Mansoura University.
is the first report of coumarins from the
genus Cynanchum.
Processing of the plant material

MATERIAL AND METHODS Air dried aerial parts of C. acutum (800

g) were soaked at room temperature in
General methanol. After solvent vaporization, the
1
H NMR spectra were recorded on a 500- crude extract (40 g) was dissolved in the
MHz spectrometer (Jeol) at Faculty of Sci- least amount of methanol and diluted with
ence, Alexandria University. Chemical shifts water and successively extracted with pe-
are given in ppm relative to TMS as internal troleum ether (40-60 °C) and methylene
standard. Infrared spectra were recorded as chloride. The petroleum ether extract (6.7
thin film cast from CHCl3, and performed on g) was saponified using alcoholic aque-
a Mattson 5000 FT-IR spectrophotometer ous sodium hydroxide (5%) and stirring
at Faculty of Science, Mansoura Univer- for 2 h, then re-extracted with petroleum
sity. GC/MS analyses were performed on ether to give the non saponifiable part (2
a Varian GC interfaced to Finnegan SSQ g). Acidification by conc. HCl (5%) and
7000 mass selective detector (SMD) with re-extraction by chloroform afforded the
ICIS V2.0 data system for MS identification saponifiable part (1.5 g). The non saponi-
of the GC components. Analyses were run fiable part of petroleum ether fraction (2 g)
with a DB-5 (J&W Scientific, Folosm, CA) was separated over neutral aluminum ox-
cross-linked fused silica capillary column ide (Al2O3) column chromatography, eluted
(30 m long, 0.25 mm internal diameter) with hexane/ethyl acetate solvent system
coated with polydimethylsiloxane (0.5 µm with increasing polarity to afford the tri-
film thickness). The oven temperature was terpenoidal compounds. Lupyl acetate was
programmed from 50 oC for 3 min., at iso- isolated with a mixture of hexane/EtOAc
thermal, then heating by 7C/ min. to 250 (49:1), lupeol with hexane/EtOAc (24:1),
o
C and isothermally for 10 min., at 250 oC. and finally a mixture of β-sitosterol and
Injector temperature was 200 oC and the vo- stigmasterol with hexane/EtOAc (13:1).
lume injected was 0.5µl. transition-line and The isolated compounds were further puri-
ion source temperature was 250 oC and 150 fied using preparative TLC using the same
o
C respectively. The mass spectrometer had solvent systems mentioned above. Lupyl
a delay of 3 min. to avoid the solvent peak acetate (0.25 g, Rf = 0.72), lupeol (0.15 g,
and then scanned from m/z 50 to m/z 300. Rf = 0.3), mixture of β-sitosterol and stig-
Ionization energy was set at 70eV (Agricul- masterol (0.1 g, Rf = 0.25).
ture Research Center, Dokki, Cairo, Egypt). The CH2Cl2 fraction (2.6 g) was separa-
Thin layer chromatography and preparative ted (1 g of which) over a silica gel CC eluted
TLC were performed on silica gel (Kieselgel with a petroleum ether/EtOAc solvent
60, GF 254) of 0.25 mm thickness. system with increasing polarity to afford
scoparone (petroleum ether/EtOAc, 3:2)
Coumarins from Cynanchum acutum Rev. Latinoamer. Quím. 37/1 (2009) 67

Table 1: 1H NMR spectra data for scopoletin Table 2: 1H NMR spectral data for scoparone.

No. of H atom δ value, ppm Integration, No. of H atom δ value, ppm Integration,
multiplicity (J, Hz) multiplicity (J, Hz)
3 6.28 1H, d (9.6)
3 6.28 1H, d(9.6)
4 7.6 1H, d, (9.6)
4 7.6 1H, d (9.6)
5 6.92 1H, s
5 6.92 1H, s
8 6.86 1H, s
8 6.86 1H, s
C-6-OMe 3.94 3H, s
C-6-OMe 3.96 3H, s
C-7-OMe 3.91 3H, s

Table 3: Identified compounds from the CH2Cl2 fraction by GC/MS

No. of peak Identification of compounds2 Mol. Wt. Rf (min.) Area%
1 Isovanillin 152.05 12.68 1.08
2 3-Oxo-alpha-ionol 208.15 16.42 1.96
3 Syringic aldehyde 182.06 16.61 2.54
4 (-)-Liliolide 196.11 17.99 2.05
2
The identification was based on high percentage of matching with the authentic spectrum using NIST
library

and scopoletin (petroleum ether/EtOAc, structures were proven by 1H NMR data.

1:1). The isolated coumarins were further The 1H NMR spectra of compounds
purified by preparative TLC to afford sco- scopoletin and scoparone (Tables 1 and 2)
poletin at Rf 0.21 (petroleum ether/EtOAc showed two doublets with coupling cons-
6:5) (0.198 g, 19.8%) and scoparone at Rf tant of 9.15 Hz at δ 6.27 and 7.60 ppm,
0.39 (petroleum ether/EtOAc, 3:2) (0.2 g, which were assigned as H-3 and H-4, res-
20.0%). A sample of the CH2Cl2 fraction pectively, characteristic for coumarins.
was analyzed by GC/MS and the identified The IR spectrum of scopoletin showed
compounds are indicated in Table 3. absorption bands at 3396 cm-1, due to a
Scopoletin: yellow needles, m.p. 204 oC, hydroxylic group; 1713 cm-1, correspon-
IR, cm 1: 3396 (OH), 1713 (CO δ-lactone), ding to carbonyl group (δ-lactone); 1611
1611 ( CH=CH ), 1565 and 1514 ( aromatic cm-1, corresponding to CH=CH group; 1565
benzene ring). and 1514 cm-1, corresponding to aromatic
Scoparone: colorless needles, m.p. 144 benzene ring.
o
C, IR, cm-1: 1713 (CO δ-lactone), 1611 The 1H NMR spectrum of scopoletin
(CH=CH ), 1565 and 1514 ( aromatic ben- showed a methoxyl group singlet at δ 3.94
zene ring). ppm and two aromatic proton singlets at δ
6.91 and 6.84 ppm which were explained
by a 6,7-disubstitution, indicating either
RESULTS AND DISCUSSION scopoletin or iso-scopoletin framework.
By addition of sodium acetate solution ac-
The purification of the extract of the dried cording to Horowitz et al. (1960), a notable
aerial parts of C. acutum afforded some bathochromic shift from 340 to 390 nm
known natural products, including β-sitos- with increase in the intensity of the band
terol, stigmasterol, lupeol, and lupyl acetate, was observed, indicating that the isolated
which have been previously isolated from the compound had a scopoletin structure (Tzu-
same species (Halim et al., 1990) where their Ching et al., 2007).
68 A. El-Demerdash, A.M. Dawidar, E.M. Keshk and M. Abdel-Mogib

The 1H NMR spectrum of scoparone was CONCLUSION

similar to that of scopoletin, except for an
additional singlet at δ 3.91 ppm indicating The phytochemical investigation of Cynan-
its identity as scoparone (Schuster et al., chum acutum L. has led to isolation and
1993), which was found to be in agreement identification of several known natural
with a molecular ion peak [M+] at m/z 206 products including two simple coumarines
in the mass spectrum. scopoletin and scoparone which are re-
In this article we report the isolation of ported for the first time from the genus.
coumarins for the first time from the genus
Cynanchum.
Acknowledgments

Thanks to Prof. Dr. Ibrahim Mashaly for

identification of the plant material.

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