(+)-bisabola-2,10-diene[1,9]oxide, a constituent of the liverwort Calypogeia suecica

Article abstract of DOI:10.1016/S0031-9422(99)00081-3

The sesquiterpene constituents of the liverwort Calypogeia suecica (Arn. and Perss.) K. Mull. were investigated. In addition to many known compounds a new sesquiterpene oxide, (+)-bisabola-2,10-diene[1,9]oxide, could be isolated and identified. The struct

Full text of DOI:10.1016/S0031-9422(99)00081-3

Phytochemistry 51 (1999) 679±682
(+)-Bisabola-2,10-diene[1,9]oxide, a constituent of the liverwort
Calypogeia suecica
Ute Warmersa, Angela Riecka, Wilfried A. Koniga,*, Hermann Muhleb
aInstitut fur Organische Chemie, Universitat Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
È
È
bAbteilung Spezielle Botanik, Universitat Ulm, 89091 Ulm, Germany
È
Received 8 January 1999; received in revised form 8 February 1999; accepted 8 February 1999
Abstract
The sesquiterpene constituents of the liverwort Calypogeia suecica (Arn. and Perss.) K. Mull. were investigated. In addition to
many known compounds a new sesquiterpene oxide, (+)-bisabola-2,10-diene[1,9]oxide, could be isolated and identi®ed. The
structure elucidation was carried out by NMR spectroscopic techniques and chemical conversions. # 1999 Elsevier Science Ltd.
All rights reserved.
Keywords: Calypogeia suecica; Jungermanniales; Liverwort; Sesquiterpene; (+)-Bisabola-2,10-diene[1,9]oxide; Enantioselective gas chromatog-
raphy
1. Introduction
& Stoianova, 1997), (Z )-g-bisabolene (Saritas, Bulow,
Fricke, Konig, & Muhle, 1998), b-sesquiphellandrene
(Connell & Sutherland, 1966), (+)-bisabola-2,10-die-
ne[1,9]oxide, bicyclogermacrene (McMurry & Bosch,
1987), anastreptene (Andersen, Ohta, Moore, & Tseng,
1978), 4,5-dehydroviridi¯orol (Warmers, Wihstutz,
Bulow, Fricke, & Konig, 1998), 9-aristolene (Wu &
Calypogeia suecica is a leafy liverwort (Hepaticae )
of the order Jungermanniales (Frahm & Frey, 1992).
Essential oil samples were obtained by hydrodistilla-
tion and analysed by gas chromatography (GC) and
GC±mass spectrometry (GC±MS). Individual com-
ponents were isolated by preparative GC and investi-
gated by NMR (1H, 13C, 1H1H-COSY, HMQC,
HMBC, NOESY). The absolute con®guration was de-
rived by polarimetric measurements and enantioselec-
tive GC using cyclodextrin phases.
Asakawa, 1988), 1(10),8-aristoladiene (Joulain
&
Konig, 1998), calarene (Joulain & Konig, 1998), b-bar-
batene (Konig, Rieck, Saritas, Hardt, & Kubeczka,
1996) and italicene (Leimner, Marschall, Meier, &
Weyerstahl, 1984).
The major component is the new sesquiterpene
oxide, (+)-bisabola-2,10-diene[1,9]oxide {(1R,6S,7S,9S)-
2H-3,4,4a,5,6,8a-hexahydro-4,7-dimethyl-2(2-methyl-
propylidene)chromene} (1) (Scheme 1).
2. Results and discussion
The mass spectrum exhibits a molecular ion signal
at m/z 220 and an elemental composition of C15H24O.
The 1H NMR spectrum shows a doublet for a
secondary methyl group at d 0.96, singlets for three
methyl groups on double bonds at d 1.67, 1.67 and
1.69, two signals for allylic protons adjacent to an
oxygen atom at d 3.78 and 4.07, respectively, and two
signals for ole®nic protons at d 5.21 and 5.57.
The following compounds were identi®ed as con-
stituents of the essential oil of C. suecica: 7-epi-ses-
quithujene (Joulain & Konig, 1998), (+)-g-curcumene
(Andersen & Syrdal, 1970), (+)-ar-curcumene (Meyers
* Corresponding author. Tel.: +49-40-4123-2824; fax: +49-40-
4123-2893.
E-mail address: wkoenig@chemie.uni-hamburg.de (W.A. Konig)
In the 13C DEPT spectrum signals of four primary
0031-9422/99/$ - see front matter # 1999 Elsevier Science Ltd. All rights reserved.
PII: S0031-9422(99)00081-3

680
U. Warmers et al. / Phytochemistry 51 (1999) 679±682
Scheme 1
carbon atoms (d 18.76, 19.35, 23.95, 26.07), three sec-
ondary carbons (d 16.52, 31.62, 36.10), six tertiary car-
bons (d 33.44, 38.73, 73.86, 75.34, 121.99, 127.03) and
two quaternary carbons (d 135.04, 140.93) were
observed. The slightly low ®eld shifted signals at d
73.86 and 75.34 were assigned to two tertiary carbons
bonded to an oxygen. The strongly low ®eld shifted
signals at d 121.99, 127.03, 135.04 and 140.93 indicate
the presence of two double bonds.
The HMQC spectrum shows the correlation of the
1H- and the 13C NMR spectrum. The connection of
the groups could be derived from the 1H1H-COSY-
and HMBC spectrum. The ole®nic methine group (d
5.21, 127.03, CH-10) shows a coupling correlation with
the methine group next to oxygen (d 4.07, 75.34, CH-
9) and with the ole®nic quaternary carbon (d 135.04,
C-11) connected to two methyl groups (d 1.67, 18.67
CH3-12; 1.69, 26.07, CH3-13).
group (d 1.38±1.51, 1.54±1.66, 16.52, CH2-5) coupling
with a methine group (d 1.38±1.51, 38.73, CH-6). This
methine group is bonded to the above mentioned
methine group next to oxygen (d 3.78, 73.86, CH-1).
The C-6 methine group further couples with a meth-
ine group (d 1.88±2.00, 33.44, CH-7) which is bonded
to a methyl group (d 0.96, 19.35, CH3-14) and to a
methylene group (d 1.20, 1.29, 36.10, CH2-8). This
methylene group is connected to the C-9 methine
group. Combination of all these data leads to structure
1.
The relative con®guration of the stereogenic centres
at C-1, C-6, C-7 and C-9 could be derived from a
NOESY spectrum. The saturation of the resonance of
H-9 results in an increase of the signal intensities of H-
1 and H-7, while H-1 interacts with H-9, H-7 and H-6.
Therefore, the protons H-1, H-6, H-7 and H-9 have to
be on the same side of the molecule (Fig. 1).
The other ole®nic methine group (d 5.57, 121.99,
CH-2) couples with the other methine group next to
oxygen (d 3.78, 73.86, CH-1) and with the ole®nic qua-
ternary carbon (d 140.93, C-3), which is connected to a
methyl group (d 1.67, 23.95, CH3-15) and to a methyl-
ene group (d 1.88±2.00, 2.03, 31.62, CH2-4). This
methylene group is connected to another methylene
The absolute con®guration was obtained by a corre-
lation reaction. 1 was hydrogenated stepwise and the
progress of the hydrogenation was followed by GC±
MS analysis. First the oxide was opened. Further
hydrogenation resulted in a simultaneous dehydration
to fully saturated bisabolanes. Enantioselective GC
using a cyclodextrin phase unambiguously proved that

U. Warmers et al. / Phytochemistry 51 (1999) 679±682
681
these bisabolanes and the corresponding hydrogen-
ation products of ( )-b-curcumene (2) (Andersen &
Syrdal, 1970) have the opposite con®guration (Scheme
1). 2 was isolated from the essential oil of Curcuma
javanica (Rieck, 1993).
As expected, 1 and the other constituents with bisa-
bolane skeleton from C. suecica, (+)-g-curcumene 3
and (+)-ar-curcumene 4, have the same absolute con-
®guration (Scheme 1).
Fig. 1. NOE e€ects of bisabola-2,10-diene[1,9]oxide (1).
3. Experimental
3.7. Mass spectrometry
3.1. Plant material
GC±MS measurements (EI, 70 eV) were carried out
with a Hewlett Packard HP 5890 gas chromatograph
coupled to a VG Analytical 70-250S mass spec-
trometer.
Calypogeia suecica was collected in the Carpathian
Mountains (Ukraine) by H. Muhle. It was identi®ed
by R. Mues, Universitat des Saarlandes, Saarbrucken,
Germany.
3.8. (+)-Bisabola-2,10-diene[1,9]oxide (1)
1H NMR (400 MHz, CDCl3): d 0.96 (3H, d, J=7.1
Hz, H-14), 1.20 (1H, m, H-8a), 1.29 (1H, ddd, J=3.6,
3.6, 12.7 Hz, H-8b), 1.38-1.51 (2H, m, H-5b, H-6),
1.54±1.66 (1H, m, H-5a), 1.67 (6H, s, H-12, H-15),
1.69 (3H, s, H-13), 1.88±2.00 (2H, m, H-4a/b, H-7),
2.03 (1H, dd, J=5.6, 17.8 Hz, H-4a/b), 3.78 (1H, bs,
H-1), 4.07 (1H, ddd, J=3.6, 8.2, 10.9 Hz, H-9), 5.21
(1H, bd, J=8.2 Hz, H-10), 5.57 (1H, d, J=5.6 Hz, H-
2); 13C NMR (125 MHz, CDCl3): d 16.52 (t, C-5),
18.76 (q, C-12), 19.35 (q, C-14), 23.95 (q, C-15), 26.07
(q, C-13), 31.62 (t, C-4), 33.44 (d, C-7), 36.10 (t, C-8),
38.73 (d, C-6), 73.86 (d, C-1), 75.34 (d, C-9), 121.99
(d, C-2), 127.03 (d, C-10), 135.04 (s, C-11), 140.93 (s,
C-3); 1H NMR (400 MHz, C6D6): d 0.85 (3H, d,
J=7.1 Hz, H-14), 1.20±1.28 (2H, m, H-8a, H-8b),
1.25±1.37 (2H, m, H-5a/b, H-6), 1.58 (3H, s, H-15),
1.60 (3H, s, H-12), 1.62 (3H, s, H-13), 1.66±1.84 (3H,
m, H-4a/b, H-7, H-5a/b), 1.88 (1H, dd, J=5.6, 17.8
Hz, H-4a/b), 3.76 (1H, s, H-1), 4.10 (1H, dd, J=8.2,
10.9 Hz, H-9), 5.46 (1H, bd, J=8.2 Hz, H-10), 5.74
(1H, d, J=5.6, 1.0 Hz, H-2); 13C NMR (125 MHz,
C6D6): d 18.01 (t, C-5), 19.95 (q, C-12), 20.72 (q, C-
14), 25.04 (q, C-15), 27.24 (q, C-13), 33.06 (t, C-4),
34.90 (d, C-7), 37.78 (t, C-8), 40.39 (d, C-6), 75.27 (d,
C-1), 76.84 (d, C-9), 124.46 (d, C-2), 129.36 (d, C-10),
134.52 (s, C-11), 140.50 (s, C-3); MS (EI, 70 eV): m/z
(rel.int.) 220 (2) [M+], 202 (3) [M+±H2O], 164 (16),
131 (13), 121 (16), 109 (12), 105 (11), 94 (100), 79 (36),
67 (16), 55 (17), 41 (24).
3.2. Hydrodistillation
The essential oil was prepared by hydrodistillation
(2 h) of aqueous homogenates of fresh and green
plants using n-hexane as collection solvent.
3.3. Gas chromatography
Orion Micromat 412 double column instrument with
25 m fused silica capillaries with polysiloxane CpSil 5
and polysiloxane CpSil 19 (Chrompack); Carlo Erba
Fractovap 2150, 4160 column instruments with 25 m
fused silica capillaries with heptakis(2,6-di-O-methyl-3-
O-pentyl)-b-cyclodextrin or heptakis(6-O-tert-butyldi-
methylsilyl-2,3-di-O-methyl)-b-cyclodextrin in OV 1701
(50%, w/w); split injection; ¯ame ionization detection;
carrier gas 0.5 bar H2.
3.4. Isolation
The isolation was carried out using preparative GC.
3.5. Preparative GC
Modi®ed Varian 1400 instrument, equipped with a
stainless steel column (1.85 m  4.3 mm) with 10%
polydimethylsiloxane SE 30 on Chromosorb W-HP;
¯ame ionization detection; helium as carrier gas at a
¯ow rate of 240 ml/min (Hardt & Konig, 1994).
3.6. NMR spectroscopy
3.9. Hydrogenation of (+)-bisabola-2,10-
diene[1,9]oxide (1)
NMR measurements were carried out with a Bruker
WM 400- or a Bruker WM 500 instrument using TMS
as internal standard.
To a soln of 1 mg of 1 in 1 ml n-hexane, 0.5 mg Pd/
C were added. The suspension was treated with H2

682
U. Warmers et al. / Phytochemistry 51 (1999) 679±682
and stirred under H2 at room temp. for 1 h. This pro-
cedure was repeated three times. The reaction mixture
was ®ltered and the reaction products were analysed
by GC±MS and by GC on various capillary columns
with polysiloxane and cyclodextrin phases.
References
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analysed by GC±MS and by GC on various capillary
columns with polysiloxane and cyclodextrin phases
and compared with the hydrogenation products of 1.
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separated on a column with heptakis(6-O-tert-butyldi-
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and 2 have the opposite con®guration.
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