Phenolic constituents from the core of Kenaf (Hibiscus cannabinus)

Article abstract of DOI:10.1016/S0031-9422(00)00473-8

Four lignans, boehmenan H {2-(4-hydroxy-3-methoxyphenyl)-5-[3-(4-hydroxy-3-methoxycinnamoyloxy)propyl] -3-hydroxymethyl-7-methoxybenzodihydrofuran}, boehmenan K {2-(4-hydroxy-3-methoxyphenyl)-5-[3-(4-hydroxycinnamoyloxy)-1-propenyl]-3- (4-hydroxy-3-methoxycinnamoyloxymethyl)-7-methoxybenzodihydrofuran}, threo-carolignan H {threo-1-(4-hydroxy-3-methox-yphenyl)-2-{4-[3-(4-hydroxy-3- methoxycinnamoyloxy)propyl]-2-methoxyphenoxy}-1,3-propanodiol}, and threo-carolignan K {threo-1-(4-hydroxy-3-methoxyphenyl)-3-(4-hydroxy-3-methoxycinnamoyloxy)-2- {4-[3-(4-hydroxycinnamoyloxy)-1-propenyl]-2-methoxyphenoxy}-1-propanol} as well as several other lignans, aldehydes and a tyramine derivative were isolated from the acetone extract of core of kenaf (Hibiscus cannabinus). All the structures were established by spectroscopic methods. The hitherto unreported ¹³C NMR spectra of some compounds are also presented and discussed. 2D NMR techniques have allowed the revision of certain previously reported ¹³C NMR assignments of some scarce naturally occurring compounds.

Full text of DOI:10.1016/S0031-9422(00)00473-8

Phytochemistry 56 (2001) 759±767
www.elsevier.com/locate/phytochem
Phenolic constituents from the core of Kenaf (Hibiscus cannabinus)
Ana M.L. Seca, Artur M.S. Silva *, Armando J.D. Silvestre, Jose A.S. Cavaleiro 1,
Fernando M.J. Domingues, Carlos Pascoal-Neto
Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
Received 14 July 2000; received in revised form 13 November 2000
Abstract
Four lignans, boehmenan
H {2-(4-hydroxy-3-methoxyphenyl)-5-[3-(4-hydroxy-3-methoxycinnamoyloxy)propyl]-3-hydroxy
methyl-7-methoxybenzodihydrofuran}, boehmenan K {2-(4-hydroxy-3-methoxyphenyl)-5-[3-(4-hydroxycinnamoyloxy)-1-propenyl]
-3-(4-hydroxy-3-methoxycinnamoyloxymethyl)-7-methoxybenzodihydrofuran}, threo-carolignan H {threo-1-(4-hydroxy-3-methox-
yphenyl)-2-{4-[3-(4-hydroxy-3-methoxycinnamoyloxy)propyl]-2-methoxyphenoxy}-1,3-propanodiol}, and threo-carolignan K {threo-
1-(4-hydroxy-3-methoxyphenyl)-3-(4-hydroxy-3-methoxycinnamoyloxy)-2-{4-[3-(4-hydroxycinnamoyloxy)-1-propenyl]-2-methoxy
phenoxy}-1-propanol} as well as several other lignans, aldehydes and a tyramine derivative were isolated from the acetone extract
of core of kenaf (Hibiscus cannabinus). All the structures were established by spectroscopic methods. The hitherto unreported 13C
NMR spectra of some compounds are also presented and discussed. 2D NMR techniques have allowed the revision of certain
previously reported 13C NMR assignments of some scarce naturally occurring compounds. # 2001Elsevier Science Ltd. All rights
reserved.
Keywords: Kenaf (Hibiscus cannabinus); Malvaceae; Lignans; Boehmenan H; Boehmenan K; threo-Carolignan H; threo-Carolignan K
1. Introduction
and structure elucidation of four new lignans, designated
as boehmenan H 1, boehmenan K 2, threo-carolignan K
3 and threo-carolignan H 4, as well as 16 other com-
pounds from the acetone extract of the core of Hibiscus
cannabinus. The detailed NMR studies of these com-
pounds 5±20 allowed us to correct some literature 13C
NMR assignments for boehmenan 5, erythro- and threo-
carolignan E, 6 and 7, and to come forward for the ®rst
time with the 13C assignments for boehmenan D 8 and
erythro-carolignan F 9.
Kenaf (Hibiscus cannabinus) is an annual dicotyledo-
nous herbaceous African plant, but also well known in
other geographical areas. In Portugal, the variety Sal-
vador has been experimentally cultivated with good
results. It has already been shown that this plant has
good features to be used in several applications, such as
antidotes to poisoning with chemicals (acids, alkali,
pesticides) and venomous mushrooms in traditional
medicine (Chifundera et al., 1994) and as source of
®bres to pulp and paper industries (Pande and Roy,
1996). Our previous studies on the chemical composi-
tion of the light petroleum extract of bark and core of
this plant resulted in the isolation of several sterols, a
triterpene, and a long chain fatty ester (Seca et al.,
2001). In the present study we report on the isolation
2. Results and discussion
The core of Hibiscus cannabinus was ®nely ground
and extracted successively with light petroleum and
acetone. The acetone extract was fractionated by its
solubility in chloroform and acetone, but almost all the
amount of this extract was soluble in chloroform. In
this way, only the latter fraction was considered; it was
successively submitted to column and preparative thin-
layer silica gel chromatographies to give four new lig-
nans 1±4 and 16 known compounds 5±20 (Fig. 1).
* Corresponding author. Tel.: +351-234370714; fax: +351-
234370084.
E-mailaddresses: arturs@dq.ua.pt or jcavaleiro@dq.ua.pt (A.M.S.
Silva).
1
Also corresponding author.
0031-9422/01/$ - see front matter # 2001Elsevier Science Ltd. All rights reserved.
PII: S0031-9422(00)00473-8

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A.M.L. Seca et al. / Phytochemistry 56 (2001) 759±767
Fig. 1. Lignans 1±9 from Hibiscus cannabinus and major connectivities observed for 2 and 3.

A.M.L. Seca et al. / Phytochemistry 56 (2001) 759±767
761
1
Due to the complexity and similarity of the H and
13C NMR spectra of compounds 1, 2, 5 and 8 and the
available large amount of 5, it was decided to start with
5 for the elucidation of these compounds. In the 1H
NMR spectrum of 5 four di€erent spin systems can be
found. One set of ABX signals corresponding to three
methylene groups appear at ꢀH 1.97±2.06 (2H, m), 2.71
(2H, t, J=7.6 Hz) and 4.23 (2H, t, J=6.5 Hz). In the
HMBC spectrum of 5, correlations between the proton
resonance at ꢀ 4.23 with that of the carbon at ꢀ 167.3
and also between that at ꢀH 2.71with carbon resonances
of an aromatic ring (ꢀC 112.4, 116.1 and 134.9) were
observed. From these results one can conclude that the
referred three methylene groups (ꢀC 30.7, 32.1and 63.7)
connect an aromatic ring to an ester group.
Fig. 2. Major HMBC connectivities observed for 22.
allowed to establish its structure as 3-hydroxymethyl-5-
(3-hydroxypropyl)-2-(4-hydroxy-3-methoxyphenyl)-7-
methoxybenzodihydrofuran 22 (Takemoto et al., 1975).
The coupling constant JH2-H3=7.8 Hz indicates that
these protons have a trans con®guration. The structure
of the third compound obtained in the transesteri®ca-
tion of 5 was identi®ed as 2,40-dihydroxy-3,30-dime-
thoxy-5-(3-hydroxypropyl)stilbene 23. The formation of
this compound 23 in the base-catalysed transesteri®ca-
tion reaction of 5 can be envisaged by the elimination of
formaldehyde, induced by sodium methoxide, and con-
sequent ring opening of the dihydrofuran moiety of
compound 22 (Scheme 1). The formation of formalde-
hyde in this reaction was con®rmed by GC±MS (m/z
30).
All the discussed spectroscopic data and the results
obtained in the transesteri®cation reaction of 5 support
the assignment of its structure to boehmenan (Take-
moto et al., 1975; Paula et al., 1995). The analysis of the
1H, 13C, COSY, HETCOR and HMBC spectra of 5
permits to correct the literature assignment of the
carbon resonances of C-5, C-7, C-10, C-40, C-40000 and
1
In the H NMR spectrum of 5 an ABC set of signals
can also be found. They are due to proton resonances of
a methine group [ꢀH 3.84±3.93 (m); ꢀC 50.7], one
benzylic methine group [ꢀH 5.50 (d, J=7.8 Hz); ꢀC 88.9]
and also a methylene group [ꢀH 4.42 (1H, dd, J=7.7 and
11.2 Hz) and 4.59 (1H, dd, J=5.1 and 11.2 Hz); ꢀC
65.4]. The inequivalence of these two methylene protons
and the multiplicity of their resonances indicate that this
methylene group is attached to a chiral methine carbon.
In the HMBC spectrum of 5 these methylene proton
resonances showed connectivities with that of the car-
bon of another ester group (ꢀC 167.0).
1
The aromatic region of the H NMR spectrum of 5
showed two AB sets of signals at ꢀH 6.23, 7.49 (2H, 2d,
J=15.9 Hz) and ꢀH 6.30, 7.60 (2H, 2d, J=15.9 Hz). The
coupling constants of these two vinylic systems indicate
that they have a trans con®guration. Correlations
between the proton resonances of these vinylic systems
with the already referred carbon resonances of ester
groups, indicate that compound 5 have two a,b-unsatu-
rated ester moieties in their structure. The presence of
these moieties was also con®rmed by the presence of a
band at 1700 cmÀ1 in the IR spectrum of 5.
The 1H NMR spectrum of 5 showed three singlets (ꢀH
5.65, 5.91and 5.92, one proton each) which disappear
after shaking its CDCl3 solution with D2O, suggesting
the presence of three phenolic protons involved in
hydrogen bonds.
C-400000
.
1
The H and 13C NMR spectral data of compound 8
were very similar to those of 5 except for one additional
methoxyl group signal in the case of 8. The presence of
one extra methoxyl group at the aromatic nucleus
1
attached to the dihydrofuran ring of 8 simpli®ed its H
NMR spectrum, compared with that of boehmenan 5.
In the case of 8 the resonances of H-20 and H-60 appear
as a singlet (ꢀH 6.67), since these protons are chemically
equivalents. In the HMBC spectrum that proton reso-
nance correlates with the carbon signals at ꢀC 89.3 (C-
2), 131.7 (C-10), 134.7 (C-40) and 147.0 (C-30,50). These
results con®rm the assignment of structure 8 to boeh-
The presence of ester groups in the structure of com-
pound 5 lead us to consider a transesteri®cation reaction
in order to aid its structure elucidation. The transester-
i®cation reaction of 5 with sodium methoxide in metha-
nol lead to the formation of three products 21±23. One of
these compounds was identi®ed as methyl ferulate 21,
suggesting the presence of esters of this acid in the struc-
ture of compound 5. The 1H NMR spectrum of the sec-
ond compound 22 obtained in this reaction showed an
aliphatic region similar to that already described for 5.
1
menan D (Paula et al., 1995). The H NMR spectral
data of 8 have been already reported, but its 13C NMR
data is now being added. The assignments of all carbon
1
The analysis of the H and 13C NMR spectra of 22, the
connectivities found in their HMBC spectrum (Fig. 2)
and the molecular ion (m/z 360) present in the EIMS
Scheme 1.

762
A.M.L. Seca et al. / Phytochemistry 56 (2001) 759±767
resonances of boehmenan D 8 were made by analysis of
its HMBC spectrum.
All this spectral data are compatible with the structure
of compound 3 shown in Fig. 1, which is called car-
olignan K.
In the case of compound 1, its HR±EIMS spectrum
shows a molecular ion at m/z 536.2053 and this is con-
sistent with the molecular formula C30H32O9 (calculated
mass: 536.2046) (corroborated by its 13C NMR spec-
trum). The 1H and 13C NMR spectra of 1 are similar to
those of boehmenan 5 although lacking the resonances of
one feruloyl moiety. The attachment site of the feruloyl
residue was determinated through the connectivities
found in its HMBC spectrum. The correlation between
the proton resonance of H-3000 and that of the carbonyl
ester carbon indicates that the feruloyl is attached to C-
3000 of the propyl chain. The presence of the ester group in
1 was also con®rmed by the presence of the band at 1700
cmÀ1 in its IR spectrum. Structure 1 was fully char-
acterised and named as boehmenan H.
Due to the presence of two chiral carbons in the 1,2,3-
trioxygenated propane moiety of carolignan K 3, two
possible diastereomers, erythro and threo, can be pre-
sent. The coupling constant JH1-H2=7.5 Hz indicates
the presence of the threo diastereomer, and so these
protons have a trans diaxial orientation (Shimomura et
al., 1987; Abraham et al., 1991).
1
The H and 13C spectra of compounds 6 and 7 are
very similar to that of carolignan K 3, except the pre-
sence of an additional methoxyl group signal and the
disappearance of those due of one double bond
00
00
(C1 ˆC2 ) in both compounds and the multiplicity of
the H-1resonance in the case of 6. Due to the presence
of this methoxyl group in 6 and 7 a trisubstituted aro-
matic ring is in place of the p-substituted phenyl ring in
the case of 3. The signals at ꢀH 6.24 and 7.49 (2H, 2d,
J=15.9 Hz), due to the vinylic protons H-200 and H-100
in calolignan K 3 were replaced by others in the alipha-
tic region due to the proton resonances of H-200 and H-
100 in the case of 6 and 7. All these data and the con-
nectivities found in the HMBC spectrum of these two
compounds allowed us to assign their structures to car-
olignan E isomers. It was also possible to correct the
literature assignments of some quaternary carbon reso-
nances, C-10, C-30, C-40, C-100, C-200, C-400, C-40000 and
C-400000 in the case of 6 and those of C-10 and C-400 in the
case of 7 (Paula et al., 1995). The proton resonance of
H-1appears in the case of 7 as a doublet and its cou-
pling constant with H-2 (JH1-H2=8.1Hz) indicates these
two protons have a trans diaxial orientation. Thus, the
structure of 7 was assigned to threo-carolignan E.
However, in the case of 6, H-1appears as a slightly
broad singlet, suggesting a small coupling constant with
H-2. The structure of 6 is then assigned to erythro-
carolignan E.
For compound 2 the molecular formula C39H36O11
(calculated mass: 680.2257) was assigned by HR±FABMS
1
(m/z 680.2285). The major di€erences between the H
NMR spectrum of compound 2 in relation with that of
boehmenan 5 were the presence of one additional double
bond and the disappearance of one methoxyl group. The
signals at ꢀH 1.97±2.06 (m, 2H) and 2.71( t, 2H) due to the
proton resonances of H-200 and H-100 in boehmenan 5 are
now for 2 being replaced by others at ꢀH 6.18±6.30 (m, 1 H)
and 6.66 (d, J=15.9 Hz, 1H), which are due to the vinylic
protons H-200 and H-100. The coupling constants of these
two protons indicate that this double bond has a trans
1
con®guration. The H NMR spectrum of 2 also showed
an AB set of signals at ꢀH 6.84 and 7.45 (2H each), which
are due to the resonances of a p-substituted phenyl ring.
The attachment position of the coumaroyl moiety was
established by the connectivities found in its HMBC
spectrum (Fig. 1). All these spectroscopic data of 2 sup-
port the assignment of the structure depicted in Fig. 1; this
compound is named boehmenan K. The coupling con-
stant JH2-H3ꢀ8 Hz in the case of compounds 1 and 2
indicates that these protons have a trans con®guration
like boehmenan 5 and boehmenan D 8.
The 1H NMR spectrum of 3 showed basically the
same resonances and coupling constants of boehmenan
K 2 (see Experimental), but with a few di€erences. The
absence of the dihydrofuran ring was suggested by the
following data: (a) the presence of a protonated carbon
resonance at ꢀC 120.0 assigned to C-600, con®rmed by
13C DEPT NMR spectrum, in place of the signal at ꢀC
127.7 due to the quaternary carbon C-9 of boehmenan
K 2. In the HETCOR spectrum this carbon resonance
correlates with the proton resonance at ꢀH 7.11 (d,
J=8.1Hz), which belongs to a trisubstituted aromatic
ring, con®rmed from their COSY spectrum; (b) some
important connectivities found in the HMBC spectrum,
as shown in Fig. 1. The HR-FABMS of 3 showed a
M+H+ ion at m/z 699.2445 consistent with the mole-
cular formula of C39H39O12 (calculated mass: 699.2442).
Compound 9 has an additional methoxyl group in
comparison with the carolignan E isomers 6 and 7 and
in this case H-300 and H-500 appear as a singlet (ꢀH 6.46),
because they are chemically equivalent. An analysis of
the spectroscopic data (1H, 13C, COSY, HETCOR and
HMBC NMR spectra and MS) showed a good agree-
ment to those assigned to carolignan F (Paula et al.,
1995). In this case H-1 also appears as a singlet, indi-
cating the presence of the erythro diastereomer.
The 1H and 13C NMR spectra of 4 are very similar to
those of boehmenan H 1. The absence of the dihy-
drofuran ring and the presence of the trioxygenated
propane moiety in the structure of 4 were suggested by
their spectral data as described above for carolignan K
3. These facts and the assigned molecular formula of
C30H34O10 (calculated mass: 577.2049) by HR-FABMS
(m/z 577.2041M+Na +) are only compatible with
the structure of 4 (Fig. 1), which was designated as

A.M.L. Seca et al. / Phytochemistry 56 (2001) 759±767
763
carolignan H. The coupling constant JH1-H2=7.5 Hz
indicates the presence of the threo isomer of carolignan
H.
3.3. Extraction and isolation
The stems were separated from foliage and air-dried
at room temperature. The core of stems was separated
from bark and then ®nely ground (1470 g) and extracted
successively with light petroleum and Me2CO. The ace-
tone extract (18.5 g) was fractionated by its solubility in
CHCl3 and Me2CO. The residue obtained from the
fraction soluble in CHCl3 was defatted with hexane and
then separated by silica gel CC. The column was eluted
with CHCl3 (fr I and II) and Me2CO (fr III). Fr I was
chromatographed on prep. silica gel TLC, eluting with
CHCl3-light petroleum (3:2), to give 5 (58.3 mg), 10
(5.7 mg), 11 (1.5 mg), 12 (10.1 mg), 13 (17.1 mg) 14
(12.1 mg), 15 (25.6 mg), and 16 (4.3 mg). Fr II on
prep silica gel TLC, eluted with CHCl3±EtOAc (4:1),
yielded 5 (206.5 mg), 14 (2.1mg), 17 (5.5 mg) and 18
(17.3 mg). Fr III on prep. TLC [silica gel, iso-PrOH±
CHCl3 (1:25)] gave 1 (13.9 mg), 2 (12.3 mg), 3 (33.5 mg),
4 (3.3 mg), 5 (64.5 mg), 6 (40.2 mg), 7 (48.5 mg), 8 (17.1
mg), 9 (25.2 mg), 18 (5.2 mg), 19 (5.8 mg) and 20 (47.1
mg).
The known compounds 10±20, were identi®ed by
comparisons of spectral data with the commercially
available vanillin 10, trans-coniferyl aldehyde 11, syr-
ingaldehyde 12, trans-sinapaldehyde 13 and p-hydroxy
benzaldehyde 17, and also with 3-hydroxy-30-methoxy-
40-hydroxypropiophenone 19 (Achenbach et al., 1988),
N-trans-feruloyl tyramine 20 (Fukuda et al., 1983;
Lajide et al., 1995) and the six lignans, pinoresinol 14, 4-
ketopinoresinol 15 (Otsuka et al., 1989), medioresinol
16 (Tsukamoto et al., 1984; Deyama et al., 1987) and
syringaresinol 18 (Ratnayake et al., 1992; Changzeng
and Zhongjian, 1997).
3. Experimental
3.1. General
1H and 13C NMR spectra were recorded in CDCl3 on
a Bruker AMX 300 at 300.13 and 75.47 MHz, respec-
tively; the chemical shifts are expressed in ꢀ (ppm)
values relative to TMS as internal reference and the
3.3.1. 2-(4-Hydroxy-3-methoxyphenyl)-5-[3-(4-hydroxy
-3-methoxycinnamoyloxy)propyl]-3-hydroxymethyl-7-
methoxybenzodihydrofuran (boehmenan H) 1
1
coupling constants J are expressed in Hz. H assign-
ments were made using 2D COSY and NOESY (mixing
time of 800 ms) experiments, while 13C assignments
were made using 2D HETCOR and HMBC experi-
ments (long range C/H coupling constants were opti-
mised to 4 and 7 Hz). MS were obtained at 70 eV
electron impact and positive FAB ionisation (nitro-
benzyl alcohol as matrix) using a VG Autospect Q mass
spectrometer. IR spectra were obtained with a MATT-
SON 7000 FTIR spectrometer. GC±MS analysis was
performed using a HP 5890 chromatograph equipped
with a mass selective detector MSD series II (electron-
impact ionization). Injector and interface temperatures
were 220 and 250ꢁC, respectively. Initial oven tempera-
ture was 30ꢁC (8 min), then 10ꢁC/min up to 200ꢁC (5
min), carrier gas helium (¯ow rate 0.9 ml/min1), split
ratio, 1:100, injections 1 ml. Fused silica capillary col-
umn DB-5 (30 mÂ0.25 mmÂ0.25 mm) was used. Prep
TLC was carried out on silica gel plates (Merck silica
gel 60 F254); spots were detected under UV (at 254 and/
or 366 nm). Phenolic compounds were detected by the
appearance of a brown colour when the TLC plates was
sprayed with a (3:2) CHCl3:py solution of FeCl3 (1%)
(Browning, 1967). Column chromatography was also
performed on silica gel (Merck silica gel 60, 70±230
mesh).
Yellowish oil, IR ꢁmax (KBr) cmÀ1: 3412 (O±H),
2952, 1700 (CˆO), 1604, 1516 (CˆC), 1430, 1271,
1032. 1H NMR: ꢀ 1.99±2.06 (2H, m, H-2000), 2.71
(2H, t, J=7.5 Hz, H-1000), 3.53±3.67 (1H, m, H-3),
3.86 (3H, s, 30-OCH3), 3.89 (3H, s, 30000-OCH3), 3.93
(3H, s, 7-OCH3), 3.86±4.00 (2H, m, H-100), 4.17±4.24
(2H, m, H-3000), 5.54 (1H, d, J=7.8 Hz, H-2), 5.64
(1H, s, 40-OH), 5.90 (1H, s, 40000-OH), 6.31(H1 ,
d,
J=15.9 Hz, H-a), 6.68 (2H, s, H-4,6), 6.87 (1H, d,
J=8.1Hz, H-5 0), 6.88±6.93 (2H, m, H-60,50000), 6.94
(1H, s, H-20), 7.04 (1H, d, J=1.8 Hz, H-20000), 7.09 (1H,
dd, J=1.8 and 8.4 Hz, H-60000), 7.62 (1H, d, J=15.9 Hz,
H-b). 13C NMR: ꢀ 30.6 (C-2000), 32.0 (C-1000), 53.7 (C-3),
56.0 (7,30,30000-OCH3), 63.5 (C-3000), 63.7 (C-100), 87.8
(C-2), 108.8 (C-20), 109.3 (C-20000), 112.3 (C-6), 114.2
(C-50), 114.7 (C-50000), 115.3 (C-a), 116.0 (C-4), 119.4
(C-60), 123.0 (C-60000), 126.9 (C-10000), 127.8 (C-9), 133.0
(C-10), 134.6 (C-5), 144.2 (C-7), 145.0 (C-b), 145.6 (C-
40), 146.6 (C-8,30), 146.7 (C-30000), 148.0 (C-40000), 167.4
(CO2R on C-3000). EIMS 70eV, m/z (rel. int.): 536 [M]+
(70), 519 (100), 506 (89), 342 (19), 324 (30), 177 (93).
HR±EIMS m/z: 536.2053, [M]+ (calculated for
C30H32O9: 536.2046).
3.3.2. 2-(4-Hydroxy-3-methoxyphenyl)-5-[3-(4-hydroxy
cinnamoyloxy)-1-propenyl]-3-(4-hydroxy-3-methoxy
cinnamoyloxymethyl)-7-methoxybenzodihydrofuran
(boehmenan K) 2
3.2. Plant material
Hibiscus cannabinus, variety Salvador, was harvested
in Figueira da Foz, Portugal, in September 1995.
Yellowish oil, IR ꢁmax (KBr) cmÀ1: 3400 (O±H), 2940,
1
1693 (CˆO), 1605, 1515 (CˆC), 1268, 1168, 832. H

764
A.M.L. Seca et al. / Phytochemistry 56 (2001) 759±767
NMR: ꢀ 3.84±3.93 (1H, m, H-3), 3.84 (3H, s, 30-OCH3),
3.92 (3H, s, 7-OCH3), 3.93 (3H, s, 30000-OCH3), 4.43 (1H,
dd, J=7.5 and 11.1 Hz, H-100), 4.59 (1H, dd, J=5.1and
11.1 Hz, H-100), 4.84 (2H, d, J=6.3 Hz, H-3000), 5.55 (1H,
d, J=7.5 Hz, H-2), 5.65 (1H, s, 40-OH), 5.91(1H, s, 40000-
OH), 6.24 (1H, d, J=15.9 Hz, H-a), 6.18±6.30 (1H, m,
H-2000), 6.33 (1H, d, J=15.9 Hz, H-a0), 6.66 (1H, d,
J=15.9 Hz, H-1000), 6.84 (2H, d, J=8.4 Hz, H-300000,500000),
6.90±6.95 (6H, m, H-4,6,20,50,60,50000), 6.98 (1H, d, J=1.8
Hz, H-20000), 7.04 (1H, dd, J=1.8 and 8.4 Hz, H-60000),
3.3.4. threo-1-(4-Hydroxy-3-methoxyphenyl)-2-{4-[3-
(4-hydroxy-3-methoxycinnamoyloxy)propyl]-2-methoxy
phenoxy}-1,3-propanodiol(threo-caroilgnan H)
4
Yellowish oil, IR ꢁmax (KBr) cmÀ1: 3413 (O±H), 2921,
1698 (CˆO), 1600, 1515 (CˆC), 1428, 1268, 1159, 1029.
1H NMR: ꢀ 1.98±2.06 (2H, m, H-2000), 2.72 (2H, t, J=7.5
Hz, H-1000), 3.94 (1H, dd, J=3.9 and 8.4 Hz, H-3), 3.58±
3.65 (1H, m, H-3), 3.89 (3H, s, 30-OCH3), 3.92 (3H, s, 7-
OCH3), 3.94 (3H, s, 30000-OCH3), 3.86±3.99 (1H, m, H-2),
4.22 (2H, t, J=6.5 Hz, H-3000), 4.96 (1H, d, J=7.5 Hz,
H-1), 5.64 (1H, s, 40-OH), 5.89 (1H, s, 40000-OH), 6.31
(1H, d, J=15.9 Hz, H-a), 6.77 (1H, dd, J=1.8 and 8.9
Hz, H-500), 6.79 (1H, s, H-300), 6.89 (1H, d, J=8.1Hz, H-
500), 6.93 (1H, d, J=8.2 Hz, H-50000), 6.85±6.94 (1H, m, H-
6 ), 6.97 (1H, s, H-20), 7.04 (1H, d, J=1.8 Hz, H-20000),
7.06 (1H, d, J=8.9 Hz, H-600), 7.09 (1H, dd, J=1.8 and
8.2 Hz, H-60000), 7.62 (1H, d, J=15.9 Hz, H-b). 13C
NMR: ꢀ 30.4 (C-2000), 32.0 (C-1000), 55.9 (30-OCH3), 56.0
(7,30000-OCH3), 61.0 (C-3), 63.6 (C-3000), 74.0 (C-1), 89.7
(C-2), 109.3 (C-20,20000), 112.3 (C-300), 114.3 (C-50), 114.7
(C-50000), 115.3 (C-a), 120.3 (C-60), 121.1 (C-600), 121.3 (C-
500), 123.1 (C-60000), 126.9 (C-10000), 131.4 (C-10), 137.6 (C-
400), 144.9 (C-b), 145.5 (C-40), 145.7 (C-100), 146.6 (C-
30000), 146.8 (C-30), 148.0 (C-40000), 151.1 (C-200), 167.3
(CO2R on C-3000). EIMS 70 eV, m/z (rel. int.): 554 [M]+
(3), 536 (6), 519 (10), 177 (30), 164 (100), 149 (30), 77
(26). HR±FABMS m/z: 577.2041[M+Na] + (calculated
for C30H34O10+Na: 577.2049).
7.45 (2H, d, J=8.7 Hz, H-200000,600000), 7.51(H1 ,
d,
J=15.9 Hz, H-b), 7.66 (1H, d, J=15.9 Hz, H-b0). 13C
NMR ꢀ: 50.4 (C-3), 55.9 (7,30,30000-OCH3), 65.2 (C-3000),
65.3 (C-100), 89.1(C-2), 108.7 (C-2 ), 109.4 (C-20000), 110.5
0
(C-6), 114.3 (C-50), 114.6 (C-a), 114.7 (C-50000), 115.3 (C-
4,a0), 115.09000 (C-300000,500000), 119.7 (C-60), 121.4 (C-2000),
123.2 (C-6 ), 126.7 (C-10000), 127.1 (C-100000), 127.7 (C-9),
130.0 (C-200000,600000), 130.6 (C-5), 132.3 (C-10), 134.3 (C-
1000), 144.4 (C-7), 144.8 (C-b0), 145.7 (C-b), 145.8 (C-40),
146.7 (C-30), 146.8 (C-30000), 148.2 (C-8,40000), 157.8 (C-
400000), 167.1 (CO2R on C-100), 167.2 (CO2R on C-3000).
FABMS m/z (rel. int.): 703 [M+Na]+ (8), 680 [M]+ (8).
HR-FABMS m/z: 680.2285 [M]+ (calculated for
C39H36O11: 680.2257).
3.3.3. threo-1-(4-Hydroxy-3-methoxyphenyl)-3-(4-hydr-
oxy-3-methoxycinnamoyloxy)-2-{4-[3-(4-hydroxycinn-
amoyloxy)-1-propenyl]-2-methoxyphenoxy}-1-propanol
(threo-carolignan K) 3
Yellowish oil, IR ꢁmax (KBr) cmÀ1: 3394 (O±H), 2917,
1702 (CˆO), 1604, 1513 (CˆC), 1428, 1166, 1031, 833.
1H NMR: ꢀ 3.83 (3H, s, 30000-OCH3), 3.90 (3H, s, 200-
OCH3), 3.92 (3H, s, 30-OCH3), 4.14±4.24 (1H, m, H-3),
4.30±4.37 (2H, m, H-2,3), 4.85 (1H, d, J=5.7 Hz, H-3000),
4.95 (1H, d, J=7.5 Hz, H-1), 5.70 (1H, s, 40-OH), 6.01
(1H, s, 40000-OH), 6.24 (1H, d, J=15.9 Hz, H-a), 6.33
(1H, d, J=15.9 Hz, H-a0), 6.22±6.34 (1H, m, H-2000), 6.64
(1H, d, J=15.9 Hz, H-1000), 6.820 (2H, d, J=8.7 Hz, H-
300000,500000), 6.88±6.92 (3H, m, H-5 ,60,50000), 6.91±6.93 (1H,
m, H-20000), 6.70±6.95 (1H, m, H-300), 6.94±7.00 (1H, m,
H-500), 7.01±7.04 (2H, m, H-20,60000), 7.11 (1H, d, J=8.1
Hz, H-600), 7.41(2H, d, J=8.7 Hz, H-200000,600000), 7.49
(1H, d, J=15.9 Hz, H-b), 7.67 (1H, d, J=15.9 Hz, H-
b0). 13C NMR: ꢀ 55.8 (200-OCH3), 55.9 (30,30000-OCH3),
63.1(C-3), 65.0 (C-3 000), 74.3 (C-1), 85.8 (C-2), 109.2 (C-
20000), 109.3 (C-20), 109.8 (C-300), 114.4 (C-a), 114.5 (C-50),
114.8 (C-50000), 114.9 (C-a0), 115.9 (C-300000,500000), 120.0 (C-
600), 120.1 (C-500), 120.3 (C-60), 122.8 (C-2000), 123.3 (C-
60000), 126.6 (C-10000), 126.8 (C-100000), 130.0 (C-200000,600000),
130.9 (C-10), 132.3 (C-400), 133.5 (C-1000), 145.0 (C-b0),
145.7 (C-40,b), 146.7 (C-30000), 146.8 (C-30), 147.8 (C-
100), 148.2 (C-40000), 150.8 (C-200), 158.2 (C-400000), 166.9
(CO2R on C-3), 167.3 (CO2R on C-3000). FABMS
3.3.5. 2-(4-Hydroxy-3-methoxyphenyl)-5-[3-(4-hydroxy
-3-methoxycinnamoyloxy)propyl]-3-(4-hydroxy-3-meth
oxycinnamoyloxymethyl)-7-methoxybenzodihydrofuran
(boehmenan) 5
Yellowish oil, IR ꢁmax (KBr) cmÀ1: 3401(O±H), 2940,
1700 (CˆO), 1602, 1515 (CˆC), 1430. 1H NMR: ꢀ 1.97±
2.06 (2H, m, H-2000), 2.71(2H, t, J=7.6 Hz, H-1000), 3.84
(3H, s, 30-OCH3), 3.90 (3H, s, 7-OCH3), 3.93 (6H, s,
30000,300000-OCH3), 3.84±3.93 (1H, m, H-3), 4.23 (2H, t,
J=6.5 Hz, H-3000), 4.42 (1H, dd, J=7.7 and 11.2 Hz, H-
100), 4.59 (1H, dd, J=5.1and 11.2 Hz, H-1 00), 5.50 (1H,
d, J=7.8 Hz, H-2), 5.65 (1H, s, 40-OH), 5.91and 5.92
(2H, 2s, 40000-OH and 400000-OH), 6.23 (1H, d, J=15.9 Hz,
H-a), 6.30 (1H, d, J=15.9 Hz, H-a0), 6.69 (1H, s, H-6),
6.71(1H, s, H-4), 6.91(2H, d, J=8.3 Hz, H-50000,500000),
0
6.92 (1H, d, J=8.1Hz, H-5 ), 6.90±6.94 (3H, m, H-
20,60,200000), 7.00 (1H, dd, J=1.7 and 8.3 Hz, H-600000),
7.05 (1H, d, J=1.7 Hz, H-20000), 7.08 (1H, dd, J=1.7 and
8.3 Hz, H-60000), 7.49 (1H, d, J=15.9 Hz, H-b), 7.60 (1H,
d, J=15.9 Hz, H-b0). 13C NMR: ꢀ 30.7 (C-2000), 32.1(C-
1000), 50.7 (C-3), 55.9 and 56.0 (4ÂOCH3), 63.7 (C-3000),
65.4 (C-100), 88.9 (C-2), 108.8 (C-20), 109.3 (C-20000), 109.4
(C-200000), 112.4 (C-6), 114.2 (C-50), 114.7 (C-a,50000,500000),
115.4 (C-a0), 116.1 (C-4), 119.7 (C-60), 123.0 (C-60000),
123.1 (C-600000), 126.7 (C-10000), 126.9 (C-100000), 127.4 (C-9),
132.5 (C-10), 134.9 (C-5), 144.1 (C-7), 144.9 (C-b0), 145.5
(C-b), 145.7 (C-40), 146.2 (C-8), 146.6 (C-30), 146.7 (C-
+
m/z (rel. int.): 721[M+Na] (5), 698 (3). HR±FABMS
m/z: 699.2445 [M+H]+ (calculated for C39H39O12:
699.2442).

A.M.L. Seca et al. / Phytochemistry 56 (2001) 759±767
765
30000,300000), 147.9 (C-40000), 148.1 (C-400000), 167.0 (CO2R on
C-100), 167.3 (CO2R on C-3000). FABMS m/z (rel. int.):
735 [M+Na]+ (4), 713 [M+H]+ (4), 518 (6), 391 (8),
329 (12).
(C-20000,200000), 112.3 (C-300), 114.3 (C-50), 114.7 (C-
50000,500000,a), 115.3 (C-a0), 120.4 (C-60), 120.6 (C-600), 121.0
(C-500), 123.0 (C-600000), 123.2 (C-60000), 126.7 (C-100000),
126.9 (C-10000), 131.1 (C-10), 137.4 (C-400), 145.0 (C-b0),
145.5 (C-b), 145.6 (C-40), 146.0 (C-100), 146.7 (C-30),
146.8 (C-30000,300000), 148.0 (C-40000), 148.1 (C-400000), 150.7
(C-200), 166.8 (CO2R on C-3), 167.3 (CO2R on C-3000).
FABMS m/z (rel. int.): 753 [M+Na]+ (12).
3.3.6. erythro-1-(4-Hydroxy-3-methoxyphenyl)-3-(4-
hydroxy-3-methoxycinnamoyloxy)-2-{4-[3-(4-hydroxy-
3-methoxycinnamoyloxy)propyl]-2-methoxyphenoxy}-1-
propanol(erythro-caroilgnan E)
6
Yellowish oil, IR ꢁmax (KBr) cmÀ1: 3511 (O±H), 2938,
3.3.8. 2-(4-Hydroxy-3,5-dimethoxyphenyl)-5-[3-(4-
hydroxy-3-methoxycinnamoyloxy)propyl]-3-(4-hydroxy
-3-methoxycinnamoyloxymethyl)-7-methoxybenzodihydro
furan (boehmenan D) 8
1
1700 (CˆO), 1631, 1592, 1513 (CˆC), 1430, 1031. H
NMR: ꢀ 1.97±2.07 (2H, m, H-2000), 2.71(2H, t, J=7.7
Hz, H-1000), 3.88 (6H, s, 30,200-OCH3), 3.92 and 3.93
(2Â3H, 2s, 2ÂOCH3), 4.22 (2H, t, J=6.5 Hz, H-3000),
4.22±4.30 (1H, m, H-3), 4.47±4.52 (2H, m, H-2,3), 4.92
Yellowish oil, IR ꢁmax (KBr) cmÀ1: 3411 (O±H), 2939,
1
1701 (CˆO), 1603, 1515 (CˆC), 1429, 1269, 1159. H
(1H, s, H-1), 5.64 (1H, s, 40-OH), 5.95 (2H, s, 40000,400000
-
NMR: ꢀ 1.99±2.08 (2H, m, H-2000), 2.72 (2H, t, J=7.5
Hz, H-1000), 3.84 (6H, s, 30,50-OCH3), 3.90 (3H, s, 7-
OCH3), 3.93 (6H, s, 30000,300000-OCH3), 3.81±3.93 (1H, m,
H-3), 4.23 (2H, t, J=6.5 Hz, H-3000), 4.44 (1H, dd,
J=7.8 and 11.1 Hz, H-100), 4.61(1H, dd, J=5.1and
11.1 Hz, H-100), 5.47 (1H, d, J=8.1Hz, H-2), 5.52 (1H,
s, 40-OH), 5.90 (2H, s, 40000,400000-OH), 6.23 (1H, d,
J=15.9 Hz, H-a), 6.30 (1H, d, J=15.9 Hz, H-a0), 6.67
(2H, s, H-20,60), 6.70 (1H, s, H-6), 6.71(1H, s, H-4),
6.91* (1H, d, J=8.1Hz, H-5 00000), 6.92* (1H, d, J=8.1
Hz, H-50000), 6.97 (1H, d, J=1.8 Hz, H-20000), 7.03 (1H, d,
J=1.8 Hz, H-200000), 7.03** (1H, dd, J=1.8 and 8.1 Hz,
H-600000), 7.08** (1H, dd, J=1.8 and 8.1 Hz, H-60000), 7.48
(1H, d, J=15.9 Hz, H-b), 7.60 (1H, d, J=15.9 Hz, H-
b0). * And ** they can be interchanged. 13C NMR: ꢀ
30.7 (C-2000), 32.1(C-1 000), 50.8 (C-3), 55.9* (7-OCH3),
56.0* (30000,300000-OCH3), 56.3 (30,50-OCH3), 63.7 (C-3000),
65.4 (C-100), 89.3 (C-2), 103.2 (C-20.60), 109.3 (C-200000),
109.4 (C-20000), 112.5 (C-6), 114.7 (C-a,50000,500000), 115.4
(C-a0), 116.1 (C-4), 123.0 (C-60000,600000), 126.6 (C-100000),
126.9 (C-10000), 127.3 (C-9), 131.7 (C-10), 134.7 (C-40),
135.0 (C-5), 144.2 (C-7), 144.9 (C-b0), 145.6 (C-b), 146.2
(C-8), 146.8 (C-30000,300000), 147.0 (C-30,50), 148.0 (C-400000),
148.2 (C-40000), 167.0 (CO2R on C-100), 167.3 (CO2R on
C-3000). *They can be interchanged. FABMS m/z (rel.
int.): 765 [M+Na]+ (35), 743 [M+H]+ (14), 742 [M]+
(17), 549 (90).
OH), 6.24 (1H, d, J=15.9 Hz, H-a), 6.30 (1H, d,
J=15.9 Hz, H-a0), 6.73±6.77 (2H, m, H-300,500), 6.83 (1H,
dd, J=1.8 and 8.1 Hz, H-60), 6.88 (1H, d, J=8.1Hz, H-
50), 6.91* (1H, d, J=8.1Hz, H-5 00000), 6.92* (1H, d,
J=8.1Hz, H-5 0000), 6.67 (1H, d, J=8.3 Hz, H-600), 7.05±
6.96 (4H, m, H-20,20000,200000,60000), 7.08 (1H, dd, J=1.8 and
8.1Hz, H-6 00000), 7.51(1H, d, J=15.9 Hz, H-b), 7.62
(1H, d, J=15.9 Hz, H-b0). *They can be interchanged.
13C NMR: ꢀ 30.3 (C-2000), 32.0 (C-1000), 55.8 (200-OCH3),
55.9 (30,30000,300000-OCH3), 62.6 (C-3), 63.6 (C-3000), 72.0
(C-1), 84.5 (C-2), 108.8 (C-20), 109.3 (C-20000,200000), 112.3
(C-300), 114.1 (C-50), 114.7 (C-50000,500000), 114.9 (C-a),
115.3 (C-a0), 119.2 (C-60), 120.7 (C-600), 121.1 (C-500),
123.0 (C-600000), 123.2 (C-60000), 126.8 (C-1000000), 126.9 (C-
100000), 131.0 (C-10), 137.4 (C-400), 144.9 (C-b ), 145.0 (C-
4 ,100), 145.2 (C-b), 146.6 (C-30), 146.7 (C-30000,300000), 148.0
(C-40000,400000), 151.3 (C-200), 167.1 (CO2R on C-3), 167.3
(CO2R on C-3000). FABMS m/z (rel. int.): 753 [M+Na]+
(35).
3.3.7. threo-1-(4-Hydroxy-3-methoxyphenyl)-3-(4-hydr-
oxy-3-methoxycinnamoyloxy)-2-{4-[3-(4-hydroxy-3-
methoxycinnamoyloxy)propyl]-2-methoxyphenoxy}-1-
propanol(threo-caroilgnan E)
7
Yellowish oil, IR ꢁmax (KBr) cmÀ1: 3413 (O±H), 2940,
1700 (CˆO), 1631, 1600, 1513 (CˆC), 1430, 1172, 1031.
1H NMR: ꢀ 1.97±2.06 (2H, m, H-2000), 2.71(2H, t, J=7.7
Hz, H-1000), 3.85, 3.93 and 3.94 (3Â3H, 3s, 3ÂOCH3),
3.90 (3H, s, 7-OCH3), 4.12 (1H, dd, J=4.7 and 11.9 Hz,
H-3), 4.22 (2H, t, J=6.5 Hz, H-3000), 4.17±4.27 (1H, m,
H-2), 4.36 (1H, dd, J=3.3 and 12.0 Hz, H-3), 4.94 (1H,
d, J=8.1 Hz, H-1), 5.69 (1H, s, 40-OH), 6.00 (2H, s,
40000,400000-OH), 6.28 (1H, d, J=15.9 Hz, H-a), 6.31(1H,
d, J=15.9 Hz, H-a0), 6.74±6.78 (1H, m, H-500), 6.78 (1H,
s, H-300), 6.85±6.94 (5H, m, H-20,50,60,50000,500000), 7.02±7.07
(4H, m, H-600,20000,60000,200000), 7.08 (1H, dd, J=1.9 and 8.1
Hz, H-600000), 7.51(1H, d, J=15.9 Hz, H-b), 7.62 (1H, d,
J=15.9 Hz, H-b0). 13C NMR: ꢀ 30.4 (C-2000), 32.0 (C-
1000), 55.8 (7-OCH3), 55.9 (30,30000,300000-OCH3), 63.0 (C-3),
63.6 (C-3000), 74.4 (C-1), 86.3 (C-2), 109.2 (C-20), 109.3
3.3.9. erythro-1-(4-Hydroxy-3-methoxyphenyl)-3-(4-
hydroxy-3-methoxycinnamoyloxy)-2-{4-[3-(4-hydroxy-
3-methoxycinnamoyloxy)propyl]-2,6-dimethoxyphenoxy}
-1-propanol(erythro-caroilgnan F)
9
Yellowish oil, IR ꢁmax (KBr) cmÀ1: 3416 (O±H), 2936,
1703 (CˆO), 1592, 1515 (CˆC), 1428, 1271, 1173, 1125.
1H NMR: ꢀ 1.96±2.09 (2H, m, H-2000), 2.71(2H, t, J=7.5
Hz, H-1000), 3.85 (6H, s, 200,600-OCH3), 3.89, 3.92 and 3.93
(3Â3H, 3s, 3ÂOCH3), 4.24 (2H, t, J=6.5 Hz, H-3000),
4.32 (1H, dd, J=3.6 and 11.7 Hz, H-3), 4.45 (1H, dd,
J=7.7 and 11.6 Hz, H-3), 4.55 (1H, m, J=3.4 Hz, H-2),
4.90 (1H, s, H-1), 5.61 (1H, s, 40-OH), 5.95 (1H, s, 400000
OH), 5.97 (1H, s, 40000-OH), 6.26 (1H, d, J=15.9 Hz,
-

766
A.M.L. Seca et al. / Phytochemistry 56 (2001) 759±767
H-a), 6.31(1H, d, J=15.9 Hz, H-a0), 6.46 (2H, s, H-
300,500), 6.77 (1H. dd, J=1,2 and 8.1 Hz, H-60), 6.87 (1H,
d, J=1.9 Hz, H-20), 7.10 (1H, d, J=16.4 Hz, H-b), 7.27
(1H, d, J=16.4 Hz, H-a). 13C NMR: ꢀ 32.0 (C-100), 34.5
(C-200), 55.9 and 56.1(2 ÂOCH3), 62.3 (C-300), 108.2 (C-
20), 109.5 (C-4), 114.4 (C-50), 118.0 (C-6), 120.6 (C-60),
120.7 (C-a), 123.5 (C-1), 129.2 (C-b), 130.5 (C-10), 133.0
(C-5), 141.3 (C-2), 145.4 (C-40), 146.6 (C-3, 30). EIMS 70
eV, m/z (rel. int.): 330 [M]+ (100), 286 (13), 253 (10),
137 (13), 77 (4).
0
d, J=8.1Hz, H-5 ), 6.90* (1H, d, J=8.1Hz, H-5 00000),
6.92* (1H, d, J=8.1Hz, H-5 0000), 7.01±7.05 (4H, m, H-
20,20000,200000,600000), 7.08 (1H, dd, J=1.5 and 8.1 Hz, H-60000),
7.52 (1H, d, J=15.9 Hz, H-b), 7.62 (1H, d, J=15.9 Hz,
H-b0). *They can be intercha0n0 ged. 13C NMR: ꢀ 30.3 (C-
0
2000), 32.7 (C-1000), 55.9 (200,6 ,30000,300000-OCH3), 56.1(3 -
OCH3), 62.5 (C-3), 63.6 (C-3000), 71.5 (C-1), 83.1 (C-2),
105.3 (C-300,500), 108.4 (C-20), 109.2 (C-200000), 109.3 (C-
20000), 114.0 (C-50), 114.6* (C-500000), 114.7* (C-50000), 115.2
(C-a0), 115.5 (C-a), 118.8 (C-60), 123.0 (C-60000,600000),
126.8 (C-10000,100000), 130.7 (C-10), 132.6 (C-100), 137.9 (C-
4000), 144.7 (C-b,40), 145.0 (C-b0), 146.6 (C-300000), 146.7 (C-
3 ,30000), 147.9 (C-400000), 148.0 (C-40000), 151.3 (C-200,600),
167.1 (CO2R on C-3), 167.3 (CO2R on C-3000). *They
can be interchanged. FABMS m/z (rel. int.): 783
[M+Na]+ (14).
3.5. Identi®cation of formaldehyde by GC±MS
The boehmenan
5
transesteri®cation mixture,
obtained as described above, was directly injected in the
GC±MS chromatograph. The identi®cation of the
formaldehyde peak was done by comparison its mass
spectrum with the equipment's mass spectral library.
Acknowledgements
3.4. Transesteri®cation of boehmenan 5
The authors thank the University of Aveiro and FCT-
Lisbon for funding the Research Unit 62/94. One of us
(A.M.L.S.) is grateful to PRAXIS XXI for a grant (BD/
3412/94).
Compound 5 (ꢀ 50 mg) was added to a 1% solution
of NaOMe in MeOH (7.5 ml) and the resulting mixture
was re¯uxed for 3 h. After this period, the mixture
was acidi®ed (pH 6) with 2 M H2SO4, extracted with
Et2O and separated by prep. silica gel TLC, eluting
with CHCl3±EtOAc (9:1). The three most abundant
spots were collected and identi®ed as methyl ferulate
21, 3-hydroxymethyl-5-(3-hydroxypropyl)-2-(4-hydroxy-
References
Abraham, R.J., Fisher, J., Loftus, P., 1991. Introduction to NMR
spectroscopy. John Wiley & Sons, Chichester.
Achenbach, H., Stocker, M., Constenla, M., 1988. Flavonoid and
È
3-methoxyphenyl)-7-methoxybenzodihydrofuran
22
and 2,40-dihydroxy-3,30-dimethoxy-5-(3-hydroxypropyl)
stilbene 23.
other constituents of Bauhinia manca. Phytochemistry 27, 1835±
1841.
Browning, B.L., 1967. Methods of wood chemistry, Vol. I. Inter-
science Publishers, New York.
3.4.1. 3-Hydroxymethyl-5-(3-hydroxypropyl)-2-(4-hydr-
oxy-3-methoxyphenyl)-7-methoxybenzodihydrofuran 22
Changzeng, W., Zhongjian, J., 1997. Lignan, phenylpropanoid and
iridoid glycosides from Pedicularis torta. Phytochemistry 45, 159±
166.
Colourless oil, H NMR: ꢀ 1.88±1.92 (2H, m, H-2000),
1
2.68 (2H, t, J=7.7 Hz, H-1000), 3.58±3.64 (1H, m, H-3),
3.70 (2H, t, J=6.3 Hz, H-3000), 3.87 and 3.89 (2Â3H, 2s,
2ÂOCH3), 3.87±3.92 (2H, m, H-100), 5.55 (1H, d, J=7.5
Hz, H-2), 5.63 (1H, s, 40-OH), 6.68 (2H, s, 0H00 -4,6), 6.95
(3H, m, H-20,50,60). 13C NMR: ꢀ 32.0 (C-1 ), 34.6 (C-
2000), 53.8 (C-3), 56.0 (7,30-OCH3), 62.3 (C-3000), 63.9 (C-
100), 87.9 (C-2), 108.8 (C-20), 112.7 (C-6), 114.2 (C-50),
115.9 (C-4), 119.4 (C-60), 127.7 (C-9), 133.1 (C-5), 135.4
(C-10), 144.2 (C-8), 145.6 (C-40), 146.5 (C-30), 146.6 (C-
7). EIMS 70 eV, m/z (rel. int.): 360 [M]+ (85), 342 (100),
330 (66), 167 (30), 137 (36), 77 (13).
Chifundera, K., Balagizi, K., Kizungu, B., 1994. Les empoisonne-
ments et leurs antidotes en medecine traditionnelle au Bushi, Zaire.
Fitoterapia 65, 307±313.
Deyama, T., Ikawa, T., Kitagawa, S., Nishibe, S., 1987. The con-
stituents of Eucommia ulmoides Oliv. V. Isolation of dihydrox-
ydehydrodiconiferyl alcohol isomers and phenolic compounds.
Chemical and Pharmaceutical Bulletin 35, 1785±1789.
Fukuda, N., Yonemitsu, M., Kimura, T., 1983. Studies on the con-
stituents of the stems of Tinospora tuberculata Beumee. N-trans- and
N-cis-feruloyl tyramine, and a new phenolic glucoside, tinotuberide.
Chemical and Pharmaceutical Bulletin 31, 156±161.
Lajide, L., Escoubas, P., Mizutani, J., 1995. Termite antifeedant
activity in Xylopia aethiopica. Phytochemistry 40, 1105±1112.
Otsuka, H., Takeuchi, M., Inoshiri, S., Sato, T., Yamasaki, K., 1989.
Phenolic compounds from Coix lachryma-jobi var. Ma-yuen. Phy-
tochemistry 28, 883±886.
3.4.2. 2,40-Dihydroxy-3,30-dimethoxy-5-(3-hydroxy
propyl)stilbene 23
Pande, H., Roy, D.N., 1996. Deligni®cation kinetics of soda pulping
of kenaf. J. Wood Chem. Technol. 16, 311±325.
Colourless oil, H NMR: ꢀ 1.89±1.92 (2H, m, H-200),
1
2.67 (2H, t, J=7.7 Hz, H-100), 3.71(2H, t, J= 6.5 Hz,
H-300), 3.90 and 3.96 (2Â3H, 2s, 2ÂOCH3), 5.67 (1H, s,
40-OH), 5.82 (1H, s, 2-OH), 6.61(1H, d, J=1.8 Hz, H-
4), 6.90 (1H, d, J=8.3 Hz, H-50), 7.00 (1H, d, J=1.8 Hz,
H-6), 7.04 (1H, dd, J=1.9 and 8.3 Hz, H-60), 7.09 (1H,
Paula, V.F., Barbosa, L.C.A., Howarth, O.W., Demuner, A.J., Cass,
Q.B., Vieira, I.J.C., 1995. Lignans from Ochroma lagopus Swartz.
Tetrahedron 51, 12453±12462.
Ratnayake, S., Fang, X.-P., Anderson, J.E., McLaughlin, J.L., 1992.
Bioactive constituents from the twigs of Asimina parvi¯ora. Journal
of Natural Products 55, 1462±1467.

A.M.L. Seca et al. / Phytochemistry 56 (2001) 759±767
767
Seca, A. M. L., Silva, A. M. S., Silvestre, A. J. D., Cavaleiro, J. A. S.,
Domingues, F. M. J., Pascoal-Neto, C., 2001. Chemical composi-
tion of the light petroleum extract of Hibiscus cannabinus bark and
core. Phytochemical Analysis, in press.
Takemoto, T., Miyase, T., Kusano, G., 1975. Boehmenan, a new lig-
nan from the roots of Boehmeria tricuspis. Phytochemistry 14, 1890±
1891.
Tsukamoto, H., Hisada, S., Nishibe, S., 1984. Lignans from bark of
Fraxinus mandshurica var. japonica and F. japonica. Chemical and
Pharmaceutical Bulletin 32, 4482±4489.
Shimomura, H., Sashida, Y., Oohara, M., 1987. Lignans from
Machilus thunbergii. Phytochemistry 26, 1513±1515.