Plant Cell Reports
Plant Cell Reports (1983) 2:105-107
© Springer-Verlag 1983
Indole Alkaloids from Cell Suspension Cultures of Tabernaemontana divaricata and Tabernanthe iboga K.-H. Pawelka and J. StOckigt Institut for Pharmazeutische Biologie, Universit~it Mt~nchen, D-8000 Mt~nchen 2, F R G
Received March 31, 1983
ABSTRACT
ranthine
From c e l l tana
suspension
divaricata
under
conditions,
alkaloids
tified.
T.
have
and
rine,
which
date
for
sperma free
expected
studying type
and i d e n -
the
alkaloid
T.
iboga
conoflorine. source to
suspensions and
(Fig.
for
mechanism
of at
Determinations: on
recorded
conoflocandi-
g4 S i n s t r u m e n t Plant
Aspidothe
(MS)
Cell
cation
cell-
were
grown
et
al.
under
the
rleata
cells
Plant
for
biogenetic
( Zenk of
1981,
screening cultures
).
They
StBckigt
et
program
for
divaricata varieata loids,
riclne
1981
the
selection
).
synthesized
six
( syn. major
T.
indole
in-
eoronaridine,
),
tracted
), appacatha-
with
the
al.
worked
up in
crude
mixture
graphed
1.5 kg of
of
on TLC
solvent
- ether
were
layer
was r e The
concentrated products and
iboga
ex-
Soll
cells
were
The
resulting
alkaloids
was
chromato-
gel, used
Xylol
Machery for
the
observed
& Nagel T.
- n-hexane
- diethylamine
2 : i : 3 : 2 : 2. Five tions
con-
way.
( Si
was
stirred
( 1M ) and
by S t B c k i g t the T.
4X diva-
reextracted.
combined,
same
system
t_~a a l k a l o i d s acetate
the
organic
alkaloidal
as d e s c r i b e d ).
in
acetate
buffer
material
the
were
5 kg T.
) were
1 ethyl
The
cells
).
grown
B5 m e d i u m
conditions
weight
were
) and
iboga
1981
5.5
cell
phases
( 1980
The
dialka-
( 12-hydroxyakuammicine
),
a
( 200 ml
of
T.
Identifi-
were
a modified
identical
5% a m m o n i a .
organic
Ervatamia
ibo.ga.
20 ml
divarlcata
200 ml p h o s p h a t e
et
eel1
the
cells
( dihydrocondylocarpine
( pericalline
source
of
taining
moved and
interesting
cultured
) and T a b e r n a n t h e
level
During
we d e t e r m i n e d in
for
( Kohl
al.
divaricata
vinervine
tubotaiwine
a good
biogenetieally
pattern
Tabernaemontana
are
alkaloids
compositions,
alkaloid
tool
at c e l l - f r e e
also
and new i n d o l e
showing
alkaloid dole
an e x c e l l e n t
investigations
1980
known
al.
represent
family
And
Experiments:
).
( fresh
days
MAT
in E I - m o d e .
Isolation
T.
et
Mass
a Finnigan
Cell-Free
26°C i n 1979
INTRODUCTION
two
of
at
( Rdffer
the
as s o l v e n t . on
at 70 eV
suspension
Speetrophoto-
obtained
Cultures,
18 d a y s
UV s p e c t r a
Elmer
methanol
Of A l k a l o i d s ,
medium
of
a Perkin
551 S u s i n g
( Zenk
Apocynaeeae
tubotai-
as m a j o r
1).
Spectroscopic
for
cultures
only
found
were
Cell
suspension
iboga,
were
). In
AND R E S U L T S
spectra
level.
cell
of T.
conoflorine
EXPERIMENTAL
meter
Both
be a g o o d
formation
cell wine
alkaloids
( voaphylline
conoflorine
apparicine,
whereas
and
grown
conoflorine,
a reasonable is
iboga
monoterpenoid
isolated
vinervine,
tubotaiwine are
Tabernaemon-
synthesized
coronaridine,
tubotaiwlne
cultures
six
been
divaricata
catharanthine, produced
of
and T a b e r n a n t h e
standard
indole
cultures
and
major
a n d were
).
divarica- ethyl-
- acetone alkaloid
eluted
= 2:
frac-
with
106 methanol Td
system 90
( Td
1 was
:
i-5
further
chloroform
i0
: 0.1
identical purple
-
and
with
after
chromatographic
0.3, CAS
grey)
data
isolated
was
for of
15
and
( CAS
: 5 : 40
water
( Td
:
i
as
). The
Apparieine
com-
for
Td
2,
1960,
Td
vine
~g/l
green
methanol two
-
diethyl-
major in
used
alkaloids
the
= 90 ) was
:
was
10
analyzed
same way alkaloids.
chloroform
: 0.02.
Ti
determined
2 ( Rf=O.9, of
1
) was
purified
were
Conoflorine
found 3.9
to
~g,
10 ~ g ,
Coro-
medium.
used
compounds
Achenbach et
butanol showed
al.
1983
- acetic the
)
and ). acid-
same R f
C02M e
H
GO2Me
Tubotaiwin¢ $'*~ ) ( Dihydrocondylocorpin )
H Conoflorine ~'~ ( Voaphyt[ine )
OH H Vinervin¢
be:
Viner-
a ratio
( Td #.l
-
be
CAS r e d
the
Tubotaiwine
to
) and
Catharanthine ~' )
,)
was
divarleata
amounts
~g,
10.4 ~g,
4.7
T.
divaricata
naridine
iboga
4
H
Coronaridine
T.
2.5
and
spectro-
). C o r o n a r i d i n e
Beck
Apporicine ( Pericolline )
Ti
The of
T.
system
and
and
conoflorine.
identified
ammonia
tubotaiwine
)
the
CAS b l u e
conoflorine.
( Rf=
and
)
of T a b e r n a e m o n t a n a
al.
and
3
2 ( but in
van
: 0.1
Td
i
for
TLC s o l v e n t -
of
acetate 1 :
observed
alkaloids
MS and
used
( CAS
4.2
-
:
described
( Rf=0.6,
: 8 :
Fraction
et
with
- ether
( ethyl
( red authentic
mixture
= 14
methanol
1 is
as
spectroscopic
1980,
purified
Td
the T L C - s y s t e m
of Td
constituent
( Gorman
= i
UV,
as e o r o n a r i d i n e
eatharanthine a typical
5 was
by
The
clearly
sample.
Td 4.1 ) with
: 3 : 0.5
identified
species
) and was
as
with
: 5 : 40
identical
into
and
TLC p u r i -
acetate
apparicine.
grey
Raffelsberger Td
for
that
after
= 15
system
the p u r i f i c a t i o n
were
is
blue
revealed
separated
Td #.2
- ethyl
solvent
as f o u n d
MS d a t a
coincided
an a u t h e n t i c
in same
TLC
were
as t u b o t a i w i n e
with
by
eeric
( benzene
identified
)
with
). UV,
indicating
2 was
( 0.32
CAS-reaetion
properties
alkaloid
spraying
properties
CAS
value
The
amine
- diethylamine
parison
an R f
=
a reddish
fication
Rf=0.2,
ammonia
),
scopic
gave
methanol 0.5,
-
solvent
and
( CAS
of v i n e r v i n e , Td
the
methanol
showed
sulfate
vinervine.
0.32 in
vinervine
colour
ammonium
those
).
purified
)
C02M e ,)
Fig I. Indole alkaloids of T.divaricata *) and T.iboga**)cell suspension cultures
107 rine which might
DISCUSSION Successful
investigations
free b i o s y n t h e s i s heteroyohimblne
of indole
type
sarpagine/ajmaline St~ckigt pension
1983
appropriate Probably during
group
1980
and
based on plant
alkaloids
of the
) and the
( Pfitzner
capable
cell sus-
of s y n t h e s i z i n g
in substantial
the most important
the i n v e s t i g a t i o n s
with C a t h a r a n t h u s
the cell-
alkaloids
( Zenk
) were
cultures
regarding
roseus
amounts.
result obtained
on h e t e r o y o h i m b i n e s cultures
tection of s t r i o t o s i d i n e
was
the de-
for m o n o t e r p e n o i d
alkaloids
and Zenk
et al.
1979
by the i m m o b i l i z e d
synthase ( Pfitzner fore s t r i c t o s i d i n e cell-free
ways i n v o l v i n g
pathways dole
and Zenk
alkaloid
ferentially.
be a cell
interference
the i n c u b a t i o n
or another plausible
enzymes
complex
in T. d i v a r i c a t a
Apparicine-
( catharanthine, ( tubotaiwine,
for cell-free
experiments,
( apparicine
vinervine
this cul-
4 alkaloid
eoronaridine
), Iboga-
), Stychnos-
) and the Quebrach-
amine-group
( conoflorine synthesize,
conditions,
only
tubotaiwlne
( Strychnos-type
). In contrast T.
under standard
two major indole
( Ouebrachamine-type
pected
that the latter
useful
for b i o s y n t h e t i c
tures
alkaloids,
). It might be ex-
culture would studies.
grown under not improved
Both
in the l o w e r
medium.
loid synthesis
be more cul-
conditions
synthesize
~g-range/l
growth
) and conoflo-
for alkaloid p r o d u c t i o n used especially
and pre-
From this point of
iboga cells
rine
in p r e s e n c e ( e.g.
or T. iboga
cells
major compounds determination
conoflorine
was
of various enzyme pre-
isolated
eonverslon
plete
formation of the When
from S t e m m a d e n i a
) and cofactors,
of conoflorine was observed.
a com-
into
three
The structural
of these products
is presently
under investigation. ACKNOWLEDGEMENTS We t h a n k nical
Mrs.
assistance
culture
Achenbach
for
and t h e
members o f
N.S.
gifts
of
providing ),
Prof.
Yunusov
reference of
the
checking
cell
the
Smith ( Leiden ~ generous P r o f . R.L. english
Our t h a n k s
are
Forschungsgemeinsehaft"
( SFB i 4 5
cell
H.
) for and t o
MAT 44 S i n s t r u m e n t
support
our
Prof.
G.N.
( Taschkent alkaloids
tech-
us w i t h
Verpoorte
manuscript.
"Deutsche
to
Prof.
R.
( Tampa ) f o r
version the
),
excellent
grateful
( Erlangen
Prof.
Mansei1
for
We a r e
( Manchester
cial
Krausch
laboratory
suspensions.
to
B.
and f o r
due for
finan-
).
REFERENCES Achenbach H, R a f f e l s b e r g e r forsch. 35b: 219-225.
the
alkaloid pattern found
this culture produces
groups,
of
from competing
cells would make
ture less valuable
incubated parations
a Finnigan
precursor
would preclude
for the chosen precursor. view the more
skeleton.
to in-
obtained
of different pathways
the different
culture
group pre-
cell-free p r e p a r a t i o n s
from such a culture
since
of biogenetic
this alkaloid
In this case
strictosidine
vent
A further pre-
to one of the d i f f e r e n t in-
groups would
that synthesized
for
of alkaloid path-
this compound.
leading
) and there-
available
for the e l u c i d a t i o n
with crude
Nagakura
strictosidine
1982
is readily
investigations
requisite
1977,
indole
). This p r e c u r s o r is now easily
synthesized
the cell-free
Aspidosperma
compound
which is the central
biogenetic p r e c u r s o r ( StSokigt
the
vestigate
be a model
alkaloids
They
after o p t i m i s a t i o n
can be
of alka-
as a good source of conoflo-
B (1980) Z.Natur-
van Beek TA, Verpoorte R, Baerheim Svendsen A (1983) Planta med. 47: 83-86. Gorman M, Neuss N, Cone N3, D e y r u p O.Am. Chem. Soe. 82: i142-I145.
3A (1960)
Kohl W, Witte B, HSfle G (1981) Z.Naturforsch. 36b: 1153-1162. Nagakura N, ROffer N, Zenk NH (1979) 3.Chem. Soc. Perkin Trans. i: 2308-2312. Pfitzner A, StBckigt 3 (1983) T e t r a h e d r o n Letters, in press. Pfitzner A, StSckigt 3 (1983) J.Chem. Soc. Chem.Commun., in press. Pfltzner U, Zenk MH 10-14.
(1982) Planta med.
RUffer N, Ei-Shagi H, N a g a k u r a (1981) FEBS Letters 129: 5-9. StSekigt 22-30.
J, Soil HJ
St6eklgt 0, Zenk MH Commun. 646448.
N, Zenk MH
(1980) Planta med.
40:
(1977) 3.Chem. Soe. Chem.
StBckigt J, Pfitzner A, Firl Cell Reports i: 36-39. Zenk MH
46:
(1980) J.Nat. Produets
Zenk MH, Ei-Shagi H, Sohulte med. Suppl. 79-101.
O (1981) Plant 43: 438-451. U (1979) Planta
Plant Cell Reports (1983) 2:105-107
© Springer-Verlag 1983
Indole Alkaloids from Cell Suspension Cultures of Tabernaemontana divaricata and Tabernanthe iboga K.-H. Pawelka and J. StOckigt Institut for Pharmazeutische Biologie, Universit~it Mt~nchen, D-8000 Mt~nchen 2, F R G
Received March 31, 1983
ABSTRACT
ranthine
From c e l l tana
suspension
divaricata
under
conditions,
alkaloids
tified.
T.
have
and
rine,
which
date
for
sperma free
expected
studying type
and i d e n -
the
alkaloid
T.
iboga
conoflorine. source to
suspensions and
(Fig.
for
mechanism
of at
Determinations: on
recorded
conoflocandi-
g4 S i n s t r u m e n t Plant
Aspidothe
(MS)
Cell
cation
cell-
were
grown
et
al.
under
the
rleata
cells
Plant
for
biogenetic
( Zenk of
1981,
screening cultures
).
They
StBckigt
et
program
for
divaricata varieata loids,
riclne
1981
the
selection
).
synthesized
six
( syn. major
T.
indole
in-
eoronaridine,
),
tracted
), appacatha-
with
the
al.
worked
up in
crude
mixture
graphed
1.5 kg of
of
on TLC
solvent
- ether
were
layer
was r e The
concentrated products and
iboga
ex-
Soll
cells
were
The
resulting
alkaloids
was
chromato-
gel, used
Xylol
Machery for
the
observed
& Nagel T.
- n-hexane
- diethylamine
2 : i : 3 : 2 : 2. Five tions
con-
way.
( Si
was
stirred
( 1M ) and
by S t B c k i g t the T.
4X diva-
reextracted.
combined,
same
system
t_~a a l k a l o i d s acetate
the
organic
alkaloidal
as d e s c r i b e d ).
in
acetate
buffer
material
the
were
5 kg T.
) were
1 ethyl
The
cells
).
grown
B5 m e d i u m
conditions
weight
were
) and
iboga
1981
5.5
cell
phases
( 1980
The
dialka-
( 12-hydroxyakuammicine
),
a
( 200 ml
of
T.
Identifi-
were
a modified
identical
5% a m m o n i a .
organic
Ervatamia
ibo.ga.
20 ml
divarlcata
200 ml p h o s p h a t e
et
eel1
the
cells
( dihydrocondylocarpine
( pericalline
source
of
taining
moved and
interesting
cultured
) and T a b e r n a n t h e
level
During
we d e t e r m i n e d in
for
( Kohl
al.
divaricata
vinervine
tubotaiwine
a good
biogenetieally
pattern
Tabernaemontana
are
alkaloids
compositions,
alkaloid
tool
at c e l l - f r e e
also
and new i n d o l e
showing
alkaloid dole
an e x c e l l e n t
investigations
1980
known
al.
represent
family
And
Experiments:
).
( fresh
days
MAT
in E I - m o d e .
Isolation
T.
et
Mass
a Finnigan
Cell-Free
26°C i n 1979
INTRODUCTION
two
of
at
( Rdffer
the
as s o l v e n t . on
at 70 eV
suspension
Speetrophoto-
obtained
Cultures,
18 d a y s
UV s p e c t r a
Elmer
methanol
Of A l k a l o i d s ,
medium
of
a Perkin
551 S u s i n g
( Zenk
Apocynaeeae
tubotai-
as m a j o r
1).
Spectroscopic
for
cultures
only
found
were
Cell
suspension
iboga,
were
). In
AND R E S U L T S
spectra
level.
cell
of T.
conoflorine
EXPERIMENTAL
meter
Both
be a g o o d
formation
cell wine
alkaloids
( voaphylline
conoflorine
apparicine,
whereas
and
grown
conoflorine,
a reasonable is
iboga
monoterpenoid
isolated
vinervine,
tubotaiwine are
Tabernaemon-
synthesized
coronaridine,
tubotaiwlne
cultures
six
been
divaricata
catharanthine, produced
of
and T a b e r n a n t h e
standard
indole
cultures
and
major
a n d were
).
divarica- ethyl-
- acetone alkaloid
eluted
= 2:
frac-
with
106 methanol Td
system 90
( Td
1 was
:
i-5
further
chloroform
i0
: 0.1
identical purple
-
and
with
after
chromatographic
0.3, CAS
grey)
data
isolated
was
for of
15
and
( CAS
: 5 : 40
water
( Td
:
i
as
). The
Apparieine
com-
for
Td
2,
1960,
Td
vine
~g/l
green
methanol two
-
diethyl-
major in
used
alkaloids
the
= 90 ) was
:
was
10
analyzed
same way alkaloids.
chloroform
: 0.02.
Ti
determined
2 ( Rf=O.9, of
1
) was
purified
were
Conoflorine
found 3.9
to
~g,
10 ~ g ,
Coro-
medium.
used
compounds
Achenbach et
butanol showed
al.
1983
- acetic the
)
and ). acid-
same R f
C02M e
H
GO2Me
Tubotaiwin¢ $'*~ ) ( Dihydrocondylocorpin )
H Conoflorine ~'~ ( Voaphyt[ine )
OH H Vinervin¢
be:
Viner-
a ratio
( Td #.l
-
be
CAS r e d
the
Tubotaiwine
to
) and
Catharanthine ~' )
,)
was
divarleata
amounts
~g,
10.4 ~g,
4.7
T.
divaricata
naridine
iboga
4
H
Coronaridine
T.
2.5
and
spectro-
). C o r o n a r i d i n e
Beck
Apporicine ( Pericolline )
Ti
The of
T.
system
and
and
conoflorine.
identified
ammonia
tubotaiwine
)
the
CAS b l u e
conoflorine.
( Rf=
and
)
of T a b e r n a e m o n t a n a
al.
and
3
2 ( but in
van
: 0.1
Td
i
for
TLC s o l v e n t -
of
acetate 1 :
observed
alkaloids
MS and
used
( CAS
4.2
-
:
described
( Rf=0.6,
: 8 :
Fraction
et
with
- ether
( ethyl
( red authentic
mixture
= 14
methanol
1 is
as
spectroscopic
1980,
purified
Td
the T L C - s y s t e m
of Td
constituent
( Gorman
= i
UV,
as e o r o n a r i d i n e
eatharanthine a typical
5 was
by
The
clearly
sample.
Td 4.1 ) with
: 3 : 0.5
identified
species
) and was
as
with
: 5 : 40
identical
into
and
TLC p u r i -
acetate
apparicine.
grey
Raffelsberger Td
for
that
after
= 15
system
the p u r i f i c a t i o n
were
is
blue
revealed
separated
Td #.2
- ethyl
solvent
as f o u n d
MS d a t a
coincided
an a u t h e n t i c
in same
TLC
were
as t u b o t a i w i n e
with
by
eeric
( benzene
identified
)
with
). UV,
indicating
2 was
( 0.32
CAS-reaetion
properties
alkaloid
spraying
properties
CAS
value
The
amine
- diethylamine
parison
an R f
=
a reddish
fication
Rf=0.2,
ammonia
),
scopic
gave
methanol 0.5,
-
solvent
and
( CAS
of v i n e r v i n e , Td
the
methanol
showed
sulfate
vinervine.
0.32 in
vinervine
colour
ammonium
those
).
purified
)
C02M e ,)
Fig I. Indole alkaloids of T.divaricata *) and T.iboga**)cell suspension cultures
107 rine which might
DISCUSSION Successful
investigations
free b i o s y n t h e s i s heteroyohimblne
of indole
type
sarpagine/ajmaline St~ckigt pension
1983
appropriate Probably during
group
1980
and
based on plant
alkaloids
of the
) and the
( Pfitzner
capable
cell sus-
of s y n t h e s i z i n g
in substantial
the most important
the i n v e s t i g a t i o n s
with C a t h a r a n t h u s
the cell-
alkaloids
( Zenk
) were
cultures
regarding
roseus
amounts.
result obtained
on h e t e r o y o h i m b i n e s cultures
tection of s t r i o t o s i d i n e
was
the de-
for m o n o t e r p e n o i d
alkaloids
and Zenk
et al.
1979
by the i m m o b i l i z e d
synthase ( Pfitzner fore s t r i c t o s i d i n e cell-free
ways i n v o l v i n g
pathways dole
and Zenk
alkaloid
ferentially.
be a cell
interference
the i n c u b a t i o n
or another plausible
enzymes
complex
in T. d i v a r i c a t a
Apparicine-
( catharanthine, ( tubotaiwine,
for cell-free
experiments,
( apparicine
vinervine
this cul-
4 alkaloid
eoronaridine
), Iboga-
), Stychnos-
) and the Quebrach-
amine-group
( conoflorine synthesize,
conditions,
only
tubotaiwlne
( Strychnos-type
). In contrast T.
under standard
two major indole
( Ouebrachamine-type
pected
that the latter
useful
for b i o s y n t h e t i c
tures
alkaloids,
). It might be ex-
culture would studies.
grown under not improved
Both
in the l o w e r
medium.
loid synthesis
be more cul-
conditions
synthesize
~g-range/l
growth
) and conoflo-
for alkaloid p r o d u c t i o n used especially
and pre-
From this point of
iboga cells
rine
in p r e s e n c e ( e.g.
or T. iboga
cells
major compounds determination
conoflorine
was
of various enzyme pre-
isolated
eonverslon
plete
formation of the When
from S t e m m a d e n i a
) and cofactors,
of conoflorine was observed.
a com-
into
three
The structural
of these products
is presently
under investigation. ACKNOWLEDGEMENTS We t h a n k nical
Mrs.
assistance
culture
Achenbach
for
and t h e
members o f
N.S.
gifts
of
providing ),
Prof.
Yunusov
reference of
the
checking
cell
the
Smith ( Leiden ~ generous P r o f . R.L. english
Our t h a n k s
are
Forschungsgemeinsehaft"
( SFB i 4 5
cell
H.
) for and t o
MAT 44 S i n s t r u m e n t
support
our
Prof.
G.N.
( Taschkent alkaloids
tech-
us w i t h
Verpoorte
manuscript.
"Deutsche
to
Prof.
R.
( Tampa ) f o r
version the
),
excellent
grateful
( Erlangen
Prof.
Mansei1
for
We a r e
( Manchester
cial
Krausch
laboratory
suspensions.
to
B.
and f o r
due for
finan-
).
REFERENCES Achenbach H, R a f f e l s b e r g e r forsch. 35b: 219-225.
the
alkaloid pattern found
this culture produces
groups,
of
from competing
cells would make
ture less valuable
incubated parations
a Finnigan
precursor
would preclude
for the chosen precursor. view the more
skeleton.
to in-
obtained
of different pathways
the different
culture
group pre-
cell-free p r e p a r a t i o n s
from such a culture
since
of biogenetic
this alkaloid
In this case
strictosidine
vent
A further pre-
to one of the d i f f e r e n t in-
groups would
that synthesized
for
of alkaloid path-
this compound.
leading
) and there-
available
for the e l u c i d a t i o n
with crude
Nagakura
strictosidine
1982
is readily
investigations
requisite
1977,
indole
). This p r e c u r s o r is now easily
synthesized
the cell-free
Aspidosperma
compound
which is the central
biogenetic p r e c u r s o r ( StSokigt
the
vestigate
be a model
alkaloids
They
after o p t i m i s a t i o n
can be
of alka-
as a good source of conoflo-
B (1980) Z.Natur-
van Beek TA, Verpoorte R, Baerheim Svendsen A (1983) Planta med. 47: 83-86. Gorman M, Neuss N, Cone N3, D e y r u p O.Am. Chem. Soe. 82: i142-I145.
3A (1960)
Kohl W, Witte B, HSfle G (1981) Z.Naturforsch. 36b: 1153-1162. Nagakura N, ROffer N, Zenk NH (1979) 3.Chem. Soc. Perkin Trans. i: 2308-2312. Pfitzner A, StBckigt 3 (1983) T e t r a h e d r o n Letters, in press. Pfitzner A, StSckigt 3 (1983) J.Chem. Soc. Chem.Commun., in press. Pfltzner U, Zenk MH 10-14.
(1982) Planta med.
RUffer N, Ei-Shagi H, N a g a k u r a (1981) FEBS Letters 129: 5-9. StSekigt 22-30.
J, Soil HJ
St6eklgt 0, Zenk MH Commun. 646448.
N, Zenk MH
(1980) Planta med.
40:
(1977) 3.Chem. Soe. Chem.
StBckigt J, Pfitzner A, Firl Cell Reports i: 36-39. Zenk MH
46:
(1980) J.Nat. Produets
Zenk MH, Ei-Shagi H, Sohulte med. Suppl. 79-101.
O (1981) Plant 43: 438-451. U (1979) Planta
