Page 1
3. Pharmacophore Identification in
Natural Cardenolides
Identificación del Farmacóforo en Cardenolidas Naturales
Arturo San Feliciano
Department of Pharmaceutical Chemistry Faculty of Pharmacy, CIETUS, IBSAL.
University of Salamanca. Salamanca. Spain
Page 2
1 - Antecedents
2 - Design and Synthesis of
Cardenolide Analogues
3 - Bioevaluation
4 - Discussion and conclusions
Contents
Page 3
TYPES
· Acute
· Chronic
· Right
· Left
· Sistolic
· Diastolic
· Congestive
CONTRACTION
VOLUME
EJECTED
VOLUME
MINUTE
FRECUENCY
CARDIAC INSUFFICIENCY
POST-CHARGE PRE-CHARGE
COMPENSATING MECHANISMS
· Miocardic hypertrophia
· hydrosaline retention
· Neurohormonal activation
Page 4
· DIURETICS · VASODILATORS · POSITIVE INOTROPICS
· b- BLOCKERS · OTHER
TREATMENT OF CARDIAC INSUFFICIENCY
Page 5
· DIURETICS · VASODILATORS · POSITIVE INOTROPICS increase intracelular cAMP
Increase intracelular Ca 2+
Modulate ionic pumps / channels
Multiple mechanism · b- BLOCKERS
· OTHER
TREATMENT OF CARDIAC INSUFFICIENCY
Page 6
· DIURETICS · VASODILATORS · POSITIVE INOTROPICS increase intracelular cAMP
b1-Agonists
Phosphodiesterase Inhibitors Increase intracelular Ca 2+
Increase Ca 2+ liberation
Sensitisers to Ca 2+ action
Modulate ionic pumps / channels
Digitalis and related Glycosides
Multiple mechanism · b- BLOCKERS
· OTHER
TREATMENT OF CARDIAC INSUFFICIENCY
Page 7
ESTRUCTURA DE LA ATPasa-Na+,K+
Page 8
ACTIVIDAD TRANSPORTADORA DE LA ATPasa-Na+,K+
E 1
E 1 P ( 3 N a + ) E 2 ( 2 K
+ )
E 2 P
3 N a +
A T P
A D P
3 N a +
2 K +
P i
2 K +
o u a b a í n a
E x t e r i o r
C i t o p l a s m a c e l u l a r
Page 9
EFFECTS AND TROUBLES
OF DIGITALIS CARDIOTONICS
PHYSIOLOGIC Positive Inotropism ( POTENCY + )
Negative Chronotropism ( RATE - ) TOXIC / ADVERSE
Page 10
PHYSIOLOGIC Positive Inotropism ( POTENCY + )
Insufficiency Negative Chronotropism ( RATE - )
Tachycardia, atrial fibrilation TOXIC / ADVERSE
EFFECTS AND TROUBLES
OF DIGITALIS CARDIOTONICS
Page 11
PHYSIOLOGIC Positive Inotropism ( POTENCY + )
Insufficiency Negative Chronotropism ( RATE - )
Tachycardia, atrial fibrilation TOXIC / ADVERSE Low Therapeutic Index Hipokalemia Bradicardia Ventricular extrasistolia Digitalisation (accumulation) Death … Nausea, vomiting, diarrhoea
EFFECTS AND TROUBLES
OF DIGITALIS CARDIOTONICS
Page 12
PHYTOCHEMICAL ANTECEDENTS Studies on Digitalis sp. endemic to the West of Spain Studies on native Spanish Conifers (Juniperus)
Page 13
Digitalis thapsi
(Scrophulariaceae)
O O
OH
gli-O
CARDENOLIDES
DIGITANOLS
OTHER
Phytochemical studies at the USAL:
digitoxin
Page 14
O
O O O
O
O
HO OH
HO
HO
O
O
OH
Molecules 5, 51- 81 (2000)
( b -D-DIG) 3 - O
O O
OH
OH
DIGOXIN
OH
Page 15
COMMUNIC ACIDS ,
PIMARIC ACIDS,
OTHER TERPENOIDS
LIGNANS
Junipers Juniperus
(sect. Oxycedrus)
Sabines Juniperus phoenicea
( sect. sabina ) HOOC
Sandaracopimaric acid
Phytochemical studies at the USAL:
Page 16
HOOC
Sandaracopimaric Acid
O O
OH
( b -D-DIG) 3 - O
DIGITOXIN
DIGITALIS - LIKE
CARDIOTONICS
?
OBJECTIVE
Page 17
1 - Antecedents
2 - Design and Synthesis of
Cardenolide Analogues
3 - Bioevaluation
4 - Discussion and conclusions
Contents
Page 18
Natural and Natural-Product Related Cardiotonics: Cardenolides
O
OH
(b-D-DIG) 3-O
O
DIGOXIN
OH
O
OH
-L-RHAMN-O
O
HO
HO
HO
OUABAIN
O
OOO
O
O
HOOH
HO
HO
O
O
OH
OH
DIGOXIN
Page 19
OH
H
O
O
O
OO
OHOH
H
H
GOMPHOSIDE
UZARIGENIN
Natural and Natural-Product Related Cardiotonics: Cardenolides
Page 20
R1
OH
R2
O
IC50 (nM)
-COCH2OH
-CH2OH
-CH2NH2.HCl
-CH2NO2
-CH2CH2NO2
-CH2NH2·HCl
-CH2NO2
1070
360
99
12
45
270
88
R1
R2
-L-rhamnose
-L-rhamnose
-L-rhamnose
-L-rhamnose
-L-rhamnose
b-D-digitoxose
b-D-digitoxose
O
N
NH
NH2
NH
Natural and Natural-Product Related Cardiotonics: Cardenolides
Page 21
OH
MeOOC
ONH
ERYTHROPHLEINE
O
Natural and Natural-Product Related Cardiotonics: Terpenoidal alkaloids
Page 22
Main Objectives
1. Synthesis of diterpenic analogues of
cardenolides, using natural pimarane
derivatives as starting materials.
2. Search for the minimum structural
requirements for cardiotonic activity.
3. Total synthesis of simpler inotropic
substances.
Page 23
PIMARANES
natural CYCLOHEXANES
synthesis
INDANES
synthesis
OO
OH
OO
OHR
1
R2
OO
Z
OH
OO
OHX
Z
Y
H
Objectives
Page 24
Cardenolide Analogues
Pimaranes
digitoxigenin Cyclohexanes
Indanes
Dinor-seco-steroids
D
D
B
A,B A,B
D C
B A
Page 25
The Pimarane Strategy
OH
O O
Gly-O
C D
glycoside
B A
steroidal A-D rings
Page 26
The Pimarane Strategy
glycoside
OH
O O
Gly-O
C D
B A
steroidal A-D rings
O
OO
Z
A B
C
OH
glucose (sugar) solubilizer
A - C rings, 5-H
lack of Ring D
Page 27
The Cyclohexane Strategy
OH
OO
Gly-O
C D
steroidal A-D rings
glycoside
A B
butenolide
Page 28
The Cyclohexane Strategy
OO
OHY
Z
C
espacer solubilizer lack of Rings
A-B and D
OH
OO
Gly-O
C D
steroidal A-D rings
glycoside
A B
butenolide
Page 29
The Indanol strategy
OH
C D
OO
Gly-O
butenolide
Cardenolide C-D rings
A-B rings and glycoside
Page 30
The Indanol strategy
OH
C D
OO
Gly-O
butenolide
Cardenolide C-D rings
A-B rings and glycoside
Y OH
R
X
D C
Butenolide or equivalent
Cardenolide C-D rings
Z
spacer (Y) and solubilizer (Z) fragments
Page 31
Butenolide or
equivalent
CD + A rings
X,Y = C, N
Z Solubilizer Lack of ring B
X
OHX
YZ
The di-nor-seco-steroid strategy
Page 32
The Pimarane-butenolide Synthesis.
OO
Z
OH
HOOC
FROM Juniperus phoenicea or Tetraclinis articulata
Page 33
The Pimarane-butenolide Synthesis.
1. The side Chain
OO
Z
OH
R = H, Ac
HOOC
FROM Juniperus phoenicea or Tetraclinis articulata
R1
R1
OR
BBN, H2O2
Page 34
The Pimarane-butenolide Synthesis.
2. The 14-hydroxyl function
R1
OR
BH3-THF
OR
OH
H
Page 35
R1
OR
BH3-THF
OR
OH
H
The Pimarane-butenolide Synthesis.
2. The 14-hydroxyl function
OR
OH
H
Page 36
The Pimarane-butenolide Synthesis.
2. The 14-hydroxyl function
R1
OR
BH3-THF
OR
OH
H
R = H, Ac, THP, TBDMS, TBDPS
OR
OH
H
Page 37
The Pimarane-butenolide Synthesis.
2. The 14-hydroxyl function
R1
OR
BH3-THF
OR
OH
H
R = H, Ac, THP, TBDMS, TBDPS
R
O
Si No association O - B
face protected
OR
OH
H
Page 38
The Pimarane-butenolide Synthesis.
3. The Butenolide
OH
OAc
H
OAc
H
OAcO
Jones; SOCl 2; CH2N2
HCl; NaOAc/Ac2O
Page 39
The Pimarane-butenolide Synthesis.
3. The Butenolide
OH
OAc
H
OAc
H
OAcO
Jones; SOCl 2; CH2N2
HCl; NaOAc/Ac2O
OH
H
O
OH
H
OOO
OH
+
Reformatsky
Page 40
The Pimarane-butenolide Synthesis.
3. The Butenolide
OO
R1
OH
OH
OAc
H
OAc
H
OAcO
Jones; SOCl 2; CH2N2
HCl; NaOAc/Ac2O
OH
H
O
OH
H
OOO
OH
+
Reformatsky
Page 41
The Pimarane-Butenolide Synthesis.
4. The End Products
R = COOH, CH 2 OH, O
O HO
HO
OH
OH
O O
R 1
OH
O O
R
OH
Page 42
The Synthesis of
Cyclohexylmethylbutenolides R
1
OO
OHR
2
R1= H, Me
R2= H, Me
OCOOH
O Cl4 steps
Mn(OAc)3
HOAc, KOAc
a:(COCl) 2/Benz
b:CH2N2; HCl
Horner
Page 43
The Synthesis of
Cyclohexylmethylbutenolides R
1
OO
OHR
2
R1= H, Me
R2= H, Me
OO
OH
OCOOH
O Cl
OO
OO
4 steps
OH
Mn(OAc)3
Br
HOAc, KOAc
a:(COCl) 2/Benz
b:CH2N2; HCl
Horner
NBS,HClO 4 n-Bu3Sn +
Page 44
The Enantioselective Synthesis of Indanols
RR
OO O
O O
O
(R = H, Me)
Page 45
The Enantioselective Synthesis of Indanols
OH
RR
OO O
O O
O
R
O
O
OOH
(R = H, Me)
(R = H) (R = Me)
S-(-)-proline
piperidine, DMFO
O O
O
Tetrahedron Asymm. 8, 2075 (1997)
HAJOS-PARRISH ketones ( ee 95-100% )
Page 46
The Indanol Synthesis: C-1-elongation
OH
O
O
OH
O
OH
O
S
SOH
HS(CH 2)3SH
BF3.Et2O
PH 3P=CH 2 HgO, THF/H 2O
BF3.Et2O
I
Page 47
The Indanol Synthesis: C-1-elongation
OH
O
O
OH
O
OH
O
O
O
S
SOH
BF3.Et2O
O
O
PH 3P=CH 2S
S
HS(CH 2)3SH
HS(CH 2)3SH
BF3.Et2O
PH 3P=CH 2
p-TsOH
HgO, THF/H 2O
HgO, THF/H 2O
BF3.Et2O
HS(CH 2)3SH TMSCl
BF3.Et2O
Page 48
The Indanol Synthesis: C-1-elongation
OH OH OH OH
CHO
OH
CHOOH OH
CHO CHOOH OH
I
BH3.THF
H2O2
PCC
PCC
1:1
1:1
BH3.THF
H2O2
II
III
Page 49
The Indanol Synthesis: C-1-elongation
OH OH OH OH
CHO
OH
CHO
I
OH OH
BH3.THF
H2O2
CHO CHOOH OH
BH3.THF
H2O2
II
PCC
PCC
1:1
1:1
OH
CHO
OH
COOMe
Ph 3P=CHCOOMe
III
III OH
COOMe
O
deprotection
Page 50
The Indanol Synthesis: Stereochemical Control
OH
CHO
OH
CHO
Y Y
X X
?
Page 51
The Indanol Synthesis: Stereochemical Control
X,Y H =O H, OH OH, H -O-(CH2)2-O- -O-(CH2)3-O- -S(CH2)3S-
DH b -0.02 +0.12 -1.64 +1.39 -1.09 -0.85 -2.98
(Kcal/mole)
OH
CHO
OH
CHO
Y Y
X X
?
Page 52
The Indanol Synthesis: Stereochemical Control
OH
CHO
OH
CHO
S
S
S
S
5% KOH / MeOH
b = 1 / 9
OH
CHO
OH
CHO
Y Y
X X
?
X,Y H =O H, OH OH, H -O-(CH2)2-O- -O-(CH2)3-O- -S(CH2)3S-
DH b -0.02 +0.12 -1.64 +1.39 -1.09 -0.85 -2.98
(Kcal/mole)
Page 53
The Indanol Synthesis: Final Products
R
H, Me
X,Y
H,H; =O; H,OH;
H,OAc;
-O-(CH2)2-O-; -O-(CH2)3-O-;
-S-(CH2)3-S-; =N-N=C(NH2)2
Z
COMe; COOMe; SMe, NO2
G H,OH; CHNO2;
N-N=C(NH2)2
OH
Z
Y
Z
Y
XX
R R
OHY
X
R
Y
X
R
G G
Page 54
The Synthesis of Ent-Indanols
O
O
O
+
O
O
N
N
NNH2N
NH2
NH2
NH2
30
R-(+)-proline
43
Page 55
OTMS
O
O
OTMS
O
H2N
OTMS
O
N
NC
OTMS
O
HO
OTMS
O
NOH
O
O
5
6a
7a
8a
9a1
a
b
c
a) TMSTf, Et3N, CH2Cl2
b) NH4OAc, NaBH3CN, MeOH
c) Piperidine, HCl/MeOH, NaBH3CN (r.t.)
OO
OHX
Z
Y
H
Synthesis of B,B-dinor-B-seco-steroids
Page 56
a) TMSTf, Et3N, CH2Cl2
c) Piperidine, HCl/MeOH, NaBH3CN (r.t.)
OO
OHX
Z
Y
H
Synthesis of B,B-dinor-B-seco-steroids
OH
O
OOTMS
O
1 11
ca
+
OTMSN
NC
OTMSN
N
NCN
12a 13a
13b12b
Page 57
+
OH
O
O
OH
O
NC
CNOH
O
NC
CNOH
O
NC
CN
+
OH
O
NO2
OH
O
NO2
OH
O
OH
O
OH
O
NCOH
O
NC
1
14 15a 15b
16a 16b 17a 17b
18a 18b
+
+
a
b
c d
e
OO
OHX
Z
Y
H
a) malononitrile, b-alanine,
HOAc / EtOH, r.t.
b) DIBAL-H 1M, hex, THF, 0ºC
c) MeNO2, EDA, D
d) H2, Pd/C (10%), EtOH, r.t.
e) TosMIC, KOtBu, EtOH,
1,2-dimethoxyethane, r.t.
Synthesis of B,B-dinor-B-seco-steroids
Page 58
OH
O
O
OH
O
COOEt
OH
O
EtOOC
OH
O
COOEt
OH
O
COOEt
OH
O
COOEt
OH
O
COOEt
1
19
20
21a
21b
22a
22b
a b c
a) Ph3P=CHCOOEt, benz., D
b) H2, Pd/C (10%), EtOH, r.t.
c) I) LDA, HMPTA, THF, -78ºC,
ii) H2C=NMe2I, THF, - 42ºC to r.t.
iii) MeI, dioxane, 90ºC, iv) NaHCO3, H2O/EtOAc, r.t.
OO
OHX
Z
Y
H
Synthesis of B,B-dinor-B-seco-steroids
Page 59
b) i) Me3SiOC(=CH2)CH=CHOMe, benz.
ii) HCl (c), CHCl3, r.t
c) H2, Pd/C (10%), EtOH, r.t.
OO
OHX
Z
Y
H
Synthesis of B,B-dinor-B-seco-steroids
OH
O
COOEt
OH
O
COOEt
EtOOC
O
EtOOC
O
EtOOC
EtO
OEt22a,22b
23 24 27
+
b
c
EtOOC
O
EtOOC
O
EtOOC
EtO
OEt25 26 28
+ c
Page 60
OO
OHX
Z
Y
H
Synthesis of B,B-dinor-B-seco-steroids
a) LAH, Et2O, r.t.
b) TBDMSTf, Et3N, CH2Cl2
EtOOC
EtO
OEt
EtO
OEt
OH
OH
HO
EtO
OEt
OH
OH
TBDMSO
2732 35
a b
Page 61
EtO
OEt
OH
OH
TBDMSO
EtO
OEt
OH
O
TBDMSO
EtO
OEt
OH
OH
TBDMSO
OH
O
TBDMSO
O
OH
O
TBDMSO
HO
OH
TBDMSO
O
HO
33 36
3537
38
39
+
a
ab
OO
OHX
Z
Y
H
Synthesis of B,B-dinor-B-seco-steroids
a) PCC, Py, CH2Cl2,
b) NaBH4, MeOH, -15ºC
Page 62
1 - Antecedents
2 - Design and Synthesis of
Cardenolide Analogues
3 - Bioevaluation
4 - Discussion and conclusions
Contents
Page 63
Bioevaluation Methods:
Spontaneously bating right atria (rat)
Electrically stimulated left atria (rat)
Page 64
Bioevaluation Methods:
Spontaneously bating right atria (rat)
contraction and rate
Electrically stimulated left atria (rat)
contraction
Page 65
Bioevaluation Methods:
Spontaneously bating right atria (rat)
contraction and rate
Electrically stimulated left atria (rat)
contraction
Na,K – ATPase (rat)
Na,K - ATPase isozymes (human)
Page 66
Bioevaluation results:
Cyclohexanebutenolides:
inactive Pimaranebutenolides: inactive // negative inotropic
Indanederivatives:
positive inotropic
Dinorsecosteroids: pending
Page 67
-50
0
50
100
150
200
250
300
% O
F C
ON
TR
OL
-8 -7 -6 -5 -4 -3
Concentration (Log M)
36b
17a
17b
CONTRACTION FORCE
RIGHT ATRIA
The Indanol Evaluation
Page 68
-50
0
50
100
150
200 %
OF
CO
NT
RO
L
-8 -7 -6 -5 -4 -3
Concentration (Log M)
36b
Digoxin
CONTRACTION FORCE
LEFT ATRIA
The Indanol Evaluation
Page 69
Indane Positive Inotropics
NO 2
N
N H 2 N
NH 2
N
N
N H 2 N
NH 2
N
NH 2
NH 2
36b
20
Page 70
The Indanol Evaluation Rat Na+,K+ - ATPase inhibition
[20 ]/ M ; [ouabain] / M
50
10 -8 10 -7 10 -6 10 -5 0
100
130
resi
du
al N
KA
act
ivit
y /
%
J. Med. Chem. 45, 127 (2002)
Page 71
IC50 (M)
Compound 20 Ouabain
2.10-6 3.10-7
5.10-4 5.10-5
The Indanol Evaluation Rat Na+,K+ - ATPase inhibition
Page 72
Human Na,K-ATPase isoenzymes activities
in absence (0) or presence of 36b
0
50
100
150
200
250
0 a
1b
1
1m
M a
1b
1
0a1
b1
1m
Ma1
b1
0a2
b1
1m
M a
2b
1
0a2
b1
1m
M a
2b
1
0 a
2b
1
5m
M a
2b
1
5m
M a
2b
1
0a3
b1
1m
M a
3b
1
0a3
b1
1m
Ma3
b1
Data #CAR 10 pmol
0
1b
1
0
1b
1
1m
M
1b
1
1m
M
1b
1
1m
M
b
1
1m
M
b
1
5m
M
b
1
5m
M
b
1
1m
M
b
1
1m
M
b
1
0
b
1
0
b
1
0
b
1
0
b
1
0
b
1
1b1
2b1
3b1
Page 73
1 - Antecedents
2 - Design and Synthesis of
Cardenolide Analogues
3 - Bioevaluation
4 - Discussion and conclusions
Contents
Page 74
The reason for the inactivity of pimarane-lactones The Reason for the Inactivity of Pimarane-butenolides?
Page 75
The Reason for the Inactivity of pimarane-butenolides?
Page 76
The Reason for the Inactivity of pimarane-butenolides?
D H = 14 kJ / mole
Page 77
The Reason for the Activity of Guanylhydrazones?
superimposition guanylhydrazone / digitoxigenin
*
Page 78
The Reason for the Activity of Guanylhydrazones?
superimposition guanylhydrazone / digitoxigenin
*
Page 79
The Reason for the Activity of Guanylhydrazones?
superimposition guanylhydrazone/erythrophleine
*
Page 80
The Reason for the Activity of Guanylhydrazones?
superimposition guanylhydrazone/erythrophleine
*
Page 81
The Reason for the Activity of Guanylhydrazones?
superimposition guanylhydrazone/erythrophleine
*
Page 82
The Reason for the Activity of Guanylhydrazones?
superimposition guanylhydrazone/erythrophleine
*
*
Page 83
The Reason for the Activity of Guanylhydrazones?
superimposition guanylhydrazone/erythrophleine
*
*
Page 84
The Ent-Indanol Evaluation
- 100
- 50
0
50
100
150
200
250
1,E - 09 1,E - 07 1,E - 05 1,E - 03
Concentration (M)
Inotr
op
ic R
esp
on
se
(% o
f C
on
tro
l)
11
15
16
19
20
22
- 100
- 50
0
50
100
150
200
250
1,E - 09 1,E - 07 1,E - 05 1,E - 03
Concentration (M)
Inotr
op
ic R
esp
on
se
(% o
f C
on
tro
l)
11
15
16
19
20
22
11 11
15 15
16 16
19 19
20 20
22 22
43
CONTRACTION FORCE
RIGHT ATRIA
Page 85
The Ent-Indanol Evaluation
Inotropic activity of guanylhydrazones (left atria)
and effect on the cardiac frequency (right atria)
compound Emax(1) Emax(2) Emax(3)
22 (norm) 129 6.5 33.7±6.3 0.3
43 (ent) 170 66.5 - 5.1±7.4 0.3
Digoxin 103 14.3 - 28.3±3.7 10-3
Ouabain 122 58.4 80.4±39.4 10-3
(1) % of basal force, (2) % of basal frequency, (3) mM
Page 86
superimposition of bishydrazone enantiomers?
N
N
NNH2N
NH2
NH2
NH2N
N
NNH2N
NH2
NH2
NH2
n e
* *
* *
Page 87
superimposition of the enantiomers?
n e
* *
*
*
Page 88
superimposition of the enantiomers
n e
* *
Page 89
superimposition of the enantiomers
n e
*
*
n e
* *
Page 90
superimposition of the enantiomers?
n e
* *
Page 91
2b1 isoenzyme activity in absence (0) or
presence of 36b (n), 43 (ent) and ouabain
0
1000
2000
3000
4000
5000
6000
dp
m/o
oci
to
0 a
2b
1
33
a2
b1
43
a2
b1
Ou
abaí
na
a2b
1
n.i
.
0
b
1
33
b1
43
b1
Ou
ab
.
b
1
0 n
.i.
enantio (43)
normal (36b)
ouabain
(0)
Page 92
Rb
Uptake
(%)
100
Column 1
compound 36b normal 43 enantio
3b11b1 2b1
50
86
isozyme b b 1 3 11 1 2b
The Ent-Indanol Evaluation
Page 93
Conclusions: - We have developed a synthetic methodology
for the preparation of a variety of cardioactive
hydroindene derivatives.
- Those belonging to the normal steroidal
series, act through inhibition of Na,K-ATPase
- Those belonging to the enantio series, being
more potent, does not act by this mechanism
- They constitute ones of the simplest
homocyclic structures reported as
cardiotonics and negative inotropics.
Page 94
Chemistry QF-USAL
Dr. Manuel Medarde
Dr. José Luis López
Dr. Fernando Tomé
Dr. Belen Hebrero
Dr. Melchor Boya
Dr. Concepción P. Melero
Dr. Luis G. Sevillano
Pharmacology - USAL
Dr. María José Montero
Dr. Rosalía Carrón
Dr. Pilar Prieto
Molecules 5, 51
Tetrahedron 45, 1815
Tetrahedron Letters 35, 8683
An. Quim 91, 89,
Synt. Commun. 25, 1377
Eur J Med Chem 26, 799
Bioorg Med Chem Lett 8, 3217
Eur J Med Chem 28, 887
Bioorg Med Chem 7, 2991
Tetrahedron 58, 1266
J. Med. Chem. 45, 127
Page 95
Biochemical Assays
Drs. Lionel G. Lelièvre, Concepción P. Melero
University of Paris 7. France
Drs. Käthi Geering, Gilles Crambert, Luis G. Sevillano
University of Lausanne. Switzerland.
Financing:
DGICYT, CICYT, JCyL, (SPAIN)
Page 97
UNIVERSITY OF SALAMANCA
1218
Page 100
The Reason for the Activity of Guanylhydrazones?
superimposition guanylhydrazone/erythrophleine
Erythrophleine conformers
Page 101
1 + 2 + 3
Superposición de secoesteroide con digitoxigenina y eritrofleína
1 + 2 2 + 3
Digitoxigenin dinorsecoesteroid erythrophleine 1 2 3
superimposition dinorsteroid, digitoxigenin, erythrophleine
Page 102
UNIVERSITY OF SALAMANCA
1218
Universidad 2oo2 Universidad 2oo2