Phytochemlsiry.
1974.Vol 13.pp. 192910 1931. PergamonPrea~.Pnntedm England.
EDGEWORTHIN,
A NEW
BIS-COUMARIN
EDGEW ORTHIA
PRIYA L. MAJUMDER.
Department
GOBINDAC.
University
(Received
Abstract-Besides
Edgeworrhia
by an oxygen
gardneri;
FROM zyxwvutsrqponmlkjihgf
GARDNERI
SENGUPTA, BISWA N. DINDA
of Pure Chemistry,
Key Word Index-Edgeworthia
zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQ
and
ASIMA CHATTERJEE
College of Science, Calcutta-700009,
India
7 Noormher1973)
Thymelaeaceae;
coumarins;
edgeworthin;
daphnoretin.
ddphnoretin
and edgeworthin.
a new his-coumarin.
was isolated from the stem-bark
of
Spectral and chemical evidence led to a structure in which two coumarin
units are linked
bridge between carbons 3 and 7’.
gardneri.
INTRODUCTION
THE FAMILY, Thymelaraceae,
which comprises of 40 genera and nearly 360 species’ is
reputed to produce coumarins2-4 of various skeletal patterns. Edgeworthia gardneri
Meissn’ (syn. E. tornentosa Nakai), of this family is known locally as Aryili. Only the cellulose constituents of this plant have been examined.6 The plant grows in the Middle-Hill
and Birch&ill areas of Darjeeling where the fruits of this plant are used as a fish-poison.
In China roots and stems are used as a remedy for bubo. In the present communication,
we report the isolation of a new his-coumarin, named edgeworthin, together with daphnoretin (1).3,7,8
RESULTS
AND
DISCUSSION
Edgeworthin, C,8H,007 (M+ 338), m.p. 280-282” (dec.) was isolated as its diacetate
from the chloroform extract of the defatted stem-bark of zyxwvutsrqponmlkjihgfedcbaZYXWVU
E. gardneri in poor yield. The
parent coumarin was generated by mild acid-hydrolysis of the pure diacetate, CzzH 1409
(Mf 422), m.p. 189”. Edgeworthin diacetate slowly dissolves in alcoholic alkali soln producing a deep-yellow colouration and is regenerated upon acidification indicating the
presence of a coumarin nucleus in its molecule. It shows UV absorption, LEgH 200, 292
sh and 323 nm, typical of 7-alkoxy coumarins.’ Its IR spectrum reveals the presence of
phenolic acetate (v,,, 1775, 1750 and 1245 cm-” and &lactone (v,,, 1720cm-I). The
60 MHz PMR spectrum in DMSO-d, of edgeworthin-diacetate
is very similar to that of
methyl daphnoretin except that the two aromatic methoxyl signals [S, 3.90 (3H, s), 3.82
(3H, s)] of the latter are replaced by those due to two methyl groups of acetoxy residues
’ HOOKER,J. D. (1879) Flora of British India, Vol. II,
’ TSCHESCHE,R., SCOTT, U. and LEGLER,G. (1963) Annalen 662, 115.
3 MAJUMDER,P. L. and SENGUPTA,G. C. (1968) J. Itx!ian Chrm. Sot. 45, 1058.
4 BHATTACHARYA,A. K. and DAS, S. C. (1971) Chem. Ind. 885.
5 CHOPRA,R. N., NAYER, S. L. and CHOPRA,I. C. (1956) Glossary zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFE
oflndian
Medicinal Plants, CSIR, New Delhi.
’ SERA, A. and GOTO, R. (1957) Mokuzai Kenkyu 27.
’ BICKOFF,E. M., LIVINGSTON,A. L. and GUGGOLZ, J. (1964) J. Agr. Food Chem. 12, 535; (1965) ibid 13, 151.
* KIRKIACHARIAN,B. and MENTZER, C. (1966) Bull. Sot. Chim. France 770.
9 BOHME,H. and SEVERIN,T. (1957) Arch. Pharm. 209, 285, 405,486,488.
I929
P. L. .MA.I~MIXK.
zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFED
G. C. SI.WLIPTA. B. N. DIWA and A. CHArrt:KJI:I~
I Y?O
16, 2.36 (6H, s)]. Moreover. the striking similarity of the chemical shifts and the splitting
patterns of three downfield protons [S, 6.38 (d; J 9.5 Hz); 8.05 (rl. J 9.5 Hz) and 7.9 (s)]
in the PMR spectrum of edgeworthin
diacetate with those of the C-3’. C-4’ and C-3 protons of methyl daphnoretin
indicates not only the his-coumarin
structure of the diacetatc.
but also suggests the mode of linkage of the two coumarin moieties to be cxactll, similar
to that in methyl daphnoretin.“.1°
The above contention
was further corroborated
by the mass spectral fragmentations
of
edgeworthin
diacetate which can be best rationalized
(see Scheme) in terms of a daphnoretin-like structure (2) for edgeworthin.
m/e 338
+
m/e
m/e 282
310
m/e165
The foregoing observations
strongly suggest that edgeworthin
should be rcprcsented by
structure (2), and this was finally verified by the following chemical evidence.
Methylation
of (2) with dimethyl sulphate in dry acetone in presence of anhydrous
potassium carbonate
furnished dimethyl--edgeworthin,
C30H1707. m.p. 231 . identical in
all respects with methyl-Ldaphnoretin
(4) obtained
by methylation
of daphnoretin
(1).
C,,H,lO.,
(M + 352) under similar reaction conditions.
Conversely, zyxwvutsrqponmlkjihgfedcbaZYX
(1) upon demethylation with boron tribromide in methylene chloride afforded (2) in almost quantilativc
yield.
EXPERIMENTAL
Melting points determined on a KGflcr block. are uncorrected.
Sihca gel was used for column chromatograph!
EtOH and IR spectra were run in
and silica gel G for TLC. UV spectra were measured in 95’%;,aldehyde-free
nujol mulls. Anhydrous
NaZSOS was used for drying solvents and petrol used had b.1’” 60 40 .411
analytical
samples \%ere tested for purity by TLC.
Isoltrfiorl o~duplzt~orrtirz (1) ad d~qworthi~~
diucrtutr
zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
(3). Air-dried powdered stem-bark ( I kg) 01‘E. gurrhri
was extracted with petrol for 48 hr and the dcfatted material was extracted with CHCI, for -I8 hr. Thiq extract
was concentrated
and kept overnight in a refrigerator.
The brown sohd was filtered from the mother lquor and
on repeated crystallization
from THF or glacial H0.4~ gave a crystalline compound
(bicld. ~~05”,,1. rn.l,. 21.4
which was characterized
as daphnoretin
(UV. IR. m.p. and TLC with authentic sample). ii (60 MHr. DMSO-d,.
TMS as Internal standard):
8.01 (IH, d. J Y.5 Hz: C-4’ E), 7.83 (IH, 5; C-4 H). 7.77--6,)35 (5H. !)I: Ar~-H). 6.86
(IH. s: C-7 OH). 6.35 (IH. d. J 9.5 Hz; C-3’ H). 3.83 (3H. s: C-6 OCH,). v~,e (&ndance
“,,): 35: (M- I?%)? 337
(1~5).3~?(2).?23(1~3).322(?~2).310(1~5),30~(6~6),295(2~?).2X1
(1.1). 191 (??I. 180(W). 171)(S).
176(7+1. I?:
t 1.7). 161(6.6). 162 (3-I). I51 (38). 148 (3.2). 146 (5,5), 145 (7). I36 (3.6). I.35 (3.S). 133 (3.3). 120 (2.5). IlO I2 2).
I 17 (3,6), I08 (3.X), Y2 (4.3). 9@(2.6). 8Y (30). /I? 31 7.5. 298.2. 93.5. The mother liquor on cvaporatlon gave a gummy
rcsiduc which was treated with Ac20’C,HiN
in the cold and the acetjlated
product after usual 11orh up \\a5
“l KIKKIACHARIAZ.B. and M~NTLFR. C. (1965) Cov~pf. Rend.
zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJ
260, 197.
Edgeworthin,
a new bis-coumarin
1931
chromatographed.
EtOAc-EtOH
(3: 1) elution gave a solid which on re-crystallization
from petrol-EtOAc
mixture gave pure (3) (yield, 0+X)3%). (Found: C, 62.42; H, 3.25; MeCO-, 20.02. C22H,409
requires: C, 62.56; H,
3.31; 2MeCO-, 20.38%). 6 (60 MHz, DMSO-d,):
8.05 (lH, zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONML
d, J 9.5 Hz; C-4 5). 7.9 (lH, s; C-4 H), 787.08
(5H,
VI: Ar--!I). 6.38 (lH, d, J 9.5 Hz; C-3’ H), 2.36 (6H, s; 2-OCOCH,).
m/e (abundance
7,): 422 (fi
6,4), 394 (5.3)
3x0(17,7), 353 (15) 352 (58) 339 (21.5), 338 (loo), 324 (1.7) 310 (3.7), 309 (5) 282 (I), 281 (2) 179 (13.9) 146 (12.6).
145 (7.5), 117 (4.9) 89 (32.9).
Isolatiori of edgeworthin (2). Edgeworthin
diacetate (3) (150 mg) was refluxed with 2N aq. MeOH-H,SO,
(25 ml) for 2 hr and MeOH was removed under reduced pressure. The solid was filtered, washed with H20, dried
and crystallized
from THF to give (2) (100 mg). (Found: C, 6380; H, 2.90. C,,H,,O,
requires: C, 63.92; H,
?95”,,). i,,,,), nm (log E): 200 (4.84). 290 (4.10) 321 (4.22): in I N KOH i,,,,,, nm (log E): 220 (5.00). 260 (4.17) 295
(4.10) 320 (4.06), 337 sh (3.99); v,,,_ cm- ’ : 3350 (OH), 1690 (> CO), 1610 (> c=C< ).
Edgeworthin dimethyl ether (4). To the soln of (2) (50 mg) in dry Me,CO (15 ml), freshly dist. Me,S04
(3 ml)
and anhyd. K,CO,
(200 mg) were added and the solution was refluxed for 4 hr. The solution was filtered hot,
washed with Me,CO, evaporated
to dryness, diluted with H20, acidified with dil. HCl, extracted with CHC13,
dried, concn and chromatographed.
CHCl, elution gave a solid (40mg) which was crystallized
from C,H,CHCIJ, m.p. 231”. (Found: C, 65.42; H. 3.77; MeO. 16.52. Calculated
for C,,H,,O,:
C, 65.57; H, 3.83; 2Me0,
16.93”/,). I.,,. nm (log 6): 205 (4.72), 219 inf (4.48), 227 (4.30) 262 (3.94) 324(4.32), 342 (4.34); v,,, cm-‘:
1725
(>C=O),
1605 and 818 (:C=C:).
6 (60MHz.
DMSO-d,):
8.05 (1H. d. J 9.5Hz: C-4 H). 7.9 (lH, s: C-4 H).
-”
7.83-7.63 (SH, m; Ar-IJ), 6.38 (1H; d, j 9.5 HZ; C-3’ IJ, 3.90 (3H, s; C-7 OCI_I,), 382 (3H;‘; C-6 zyxwvutsrqponmlkjihgfed
bCI&j.
Demethylation zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
of daphnoretin zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
(1). To the solution of (1) (750 mg) in CH,Cl,
(100 ml), BBr, (3 ml) was added
dropwise with stirring; the solution was stirred for 12 hr and then kept for 48 hr. The excess of the reagent was
destroyed with H,O and the solvent evaporated. The solid was filtered and dried to give crude (2). After acetylating a part of it with Ac20/CSH,N
the product was chromatographed.
The EtOAc-EtOH
(3: 1) eluate gave a
solid which on crystallizations
from petrol-EtOAc
mixture gave a product, m.p. 189”, identical (m.m.p., co-TLC
and superimposable
IR spectra) with (3). Another part of crude (2) was methylated
with Me,SO,
following the
previous method and the methylated
product was worked up in the usual way to furnish a crystalline product,
m.p. 231’ (C,H,-CHCl,),
identical (m.m.p., co-TLC and superimposable
IR spectra) with (4).
M ethyl&on
ofdaphnoretin
(1). Daphnoretin
(1). was methylated
with Me,SO,
in the usual manner and the
methylated product was crystallized from C,H,-CHCl,
mixture to give (4) m.p. 231”.
Acknowledgements-Dr.
B. C. Das, CNRS, Gif-sur-Yvette,
France is thanked for the mass spectra, as are Dr.
D. N. Roy, University of Toronto, Canada for the PMR spectra and Dr. N. L. Dutta, HEM, India for the IR
spectra. G.C.S. is thankful to Principal M. K. Chatterjee and Professor S. N. Dhar of Hooghly Mohsin College,
Hooghly, India for encouragement
and to the Government
of West Bengal for financial assistance. B.N.D. thanks
CSIR, India also for financial support.
PRIYA MAJUMDER