Accepted Manuscript Discovery and Pharmacological Profile of New Hydrophilic 5-HT4 Receptor Antagonists Bjarne Brudeli, Mirusha Navaratnarajah, Kjetil Wessel Andressen, Ornella Manfra, Lise Román Moltzau, Nils Olav Nilsen, Finn Olav Levy, Jo Klaveness PII: DOI: Reference:
S0960-894X(14)00721-5 http://dx.doi.org/10.1016/j.bmcl.2014.06.083 BMCL 21802
To appear in:
Bioorganic & Medicinal Chemistry Letters
Received Date: Revised Date: Accepted Date:
29 May 2014 26 June 2014 28 June 2014
Please cite this article as: Brudeli, B., Navaratnarajah, M., Andressen, K.W., Manfra, O., Moltzau, L.R., Nilsen, N.O., Levy, F.O., Klaveness, J., Discovery and Pharmacological Profile of New Hydrophilic 5-HT4 Receptor Antagonists, Bioorganic & Medicinal Chemistry Letters (2014), doi: http://dx.doi.org/10.1016/j.bmcl.2014.06.083
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Discovery and Pharmacological Profile of New Hydrophilic 5-HT4 Receptor Antagonists
Bjarne Brudelia,d, Mirusha Navaratnarajah,b,d, Kjetil Wessel Andressenb,c, Ornella Manfrab,c, Lise Román Moltzaub,c, Nils Olav Nilsena, Finn Olav Levyb,c, Jo Klavenessd† a
Drug Discovery Laboratory AS, Oslo Innovation Center, N-0349 Oslo, Norway
b
Department of Pharmacology, Faculty of Medicine, University of Oslo and Oslo University Hospital, PO Box
1057 Blindern, N-0316 Oslo, Norway c
K.G. Jebsen Cardiac Research Centre and Center for Heart Failure Research, Faculty of Medicine, University
of Oslo, Norway d
Department of Medicinal Chemistry, School of Pharmacy, University of Oslo, N-0316 Oslo, Norway
†
Corresponding author: School of Pharmacy, University of Oslo, P.O. Box 1068 Blindern, N-0316 Oslo,
Norway. Phone: +47-22855043, Fax: +47-22857975, E-mail: [email protected]
Abstract The synthesis and pharmacological data of some new and potent hydrophilic 5-HT4 receptor antagonists are described. Propanediol derivative 25 was identified as a potent antagonist with low affinity for the hERG potassium channel and promising pharmacokinetics. Introduction Serotonin (5-hydroxytryptamine) is an important neurotransmitter and is a locally-acting signalling molecule in the human body. Serotonin is produced in enterochromaffin cells in the gastrointestinal tract; it is taken up, stored and released from blood platelets and is found in both the central and peripheral nervous system. The pharmacological action of serotonin is
1
mediated through seven different receptor subtypes (5-HT1-7), which are all G-coupled receptors, except the 5-HT3 receptor which is a ligand-gated ion channel.1 Several of the serotonin receptors are playing a role in various disorders, and recent investigations have brought new attention to the 5-HT4 receptor as a potential drug target in both the central nervous system (CNS) and in peripheral organs and tissues. The 5-HT4 receptor couples positively to adenylyl cyclase; activation of the receptor increases the intracellular cyclic AMP (cAMP) concentration, activates protein kinase A (PKA) and modulates intracellular responses. 2 Eleven different splice variants of the human 5-HT4 receptor are known today, at least four of them 5-HT4(a, b, g, i), are found in heart tissue.3,4 Increased expression of the 5-HT4(b) isoform in the atrium and left ventricle of chronic arrhythmic and failing hearts has recently been reported.5,6 The positive chronotropic and inotropic effect of serotonin through the 5-HT4 receptor may be deleterious in these conditions, and the use of 5-HT4 receptor antagonists in treatment of atrial fibrillation and heart failure has been evaluated in both animal models and humans.7,8,9,10 The potentially harmful cardiac effects of serotonin through the 5-HT4 receptor regarding atrial fibrillation and heart failure, and also the involvement of this receptor in aldosterone secretion, has made the 5-HT4 receptor a promising target of new and selective 5-HT4 receptor antagonists. Unfortunately, several drugs binding to serotonin receptors have shown low selectivity or affinity for the human ether-á-go-go-related gene (hERG) potassium ion channel, a tetrameric channel with six membrane-spanning domains, which has a crucial role in cardiac repolarization. Inhibition of this channel may cause prolongation of the cardiac action potential, reflected in the electrocardiogram as prolongation of the QT interval and predisposing to ventricular arrhythmias, also known as torsades de pointes (TdP). Cisapride, a partial 5-HT4 receptor agonist used to treat irritable bowel syndrome, was withdrawn from the market after several reports of drug-induced long QT syndrome.11
2
All new drug candidates should be screened for their ability to reduce hERG current in the early stage of lead discovery. Several drugs have affinity for this channel, but compounds with an alkaline nitrogen have a greater risk for binding to the hERG potassium ion channel. Several strategies are used to avoid hERG toxicity: reducing the alkalinity of nitrogen, lipophilicity and introduction of ionizable groups have been reported to reduce binding to the hERG potassium channel.12 The structural requirements of 5-HT4 receptor antagonists are well defined, and an aromatic moiety, followed by a hydrogen bond acceptor and an alkaline nitrogen atom are the cornerstones in the pharmacophore model.13 Replacing an amine with a corresponding amide is reported in the literature to mitigate hERG affinity for some T-type calcium channel blockers.12 This strategy is not possible for 5-HT4 receptor antagonists with the alkaline nitrogen as a major contributor to receptor binding, and an amide 5-HT4 antagonist with low receptor binding has previously been synthesized in our laboratory. 14 Reducing lipophilicity and creating zwitterions are however promising strategies for reducing the cardiotoxic potential of new drug candidates with effect on the serotonergic system. Recent studies suggest positive effects of 5-HT4 receptor agonists on cognitive and behavioural properties in animal models of Alzheimer’s disease, possibly through modulation of amyloidogenesis.15,16 It is therefore possible that 5-HT4 receptor antagonists which access the CNS can give undesirable side effects. We have previously reported 5-HT4 receptor antagonists with carboxylic acid groups as a promising strategy to minimize entrance into the central nervous system as well as reducing the affinity for the hERG potassium channel.17,18,19 In this letter we report some new promising acidic N-aryl sulfonamides and carboxylic acids as potent 5-HT4 receptor antagonists. This letter also describes a hydrophilic propandiol derivative with promising receptor binding and pharmacokinetic properties.
3
The starting materials N-(4-piperidinylmethyl)-1H-indole-3-carboxamide (1), N-(4piperidinylmethyl)-3,4-dihydro-2H-[1,3]oxazino[3,2-a]indole-10-carboxamide (6), N-(4piperidinylmethyl)-1,4-benzodioxane-5-carboxamide (13) and 4-piperidinylmethyl-3,4dihydro-2H-[1,3]oxazino[3,2-a]indole-10-carboxylate (20) were synthesized according to literature references.17,18,19 Binding affinities and 5-HT4 antagonist properties were determined for GR113808, SB207266 and compounds 4, 5, 9–12, 16–19 and 21–25 by competitive binding and concentration-dependent inhibition of 5-HT-stimulated adenylyl cyclase activity in membranes from HEK293 cells stably expressing the human 5-HT4(b) receptor. pKi and pKbvalues from competition of [3H]GR113808 binding and from antagonism of 5-HT4-stimulated adenylyl cyclase (AC) activity, respectively, for GR113808, SB207266 and compounds 4, 5, 9–12, 16–19 and 21–25 are summarized in Table 1 and 2. The synthesis of acidic N-aryl sulfonamide derivatives 4, 5, 9–12 and 16–19 are outlined in Scheme 1 and the compounds are shown in Table 1. Alkylation of aminopiperidines 1, 6 and 13 with 4-nitrobenzyl bromide in refluxing acetone in the presence of potassium carbonate afforded the aryl nitro intermediates 2, 7 and 14 in good yields. Reduction of the aryl nitro groups with hydrogen and palladium on activated carbon provided the N-aryl amines 3, 8 and 15. Finally, sulfonation of the corresponding N-aryl amines with different sulfonyl chlorides in a cooled mixture of dichloromethane and pyridine provided the N-aryl sulfonamides 4, 5, 9–12 and 16–19 in low to moderate yields. Cyclohexane 4 and benzyl sulfonamide 5 derivatives showed low binding affinities in the micromolar range. By introducing the oxazino[3,2-a]-ring to the indole skeleton, receptor binding was increased and we found that N-aryl sulfonamides 9–12 had potent binding affinities in the nanomolar range. The indole amides 4 and 5 have only one hydrogen bonding
4
position, while the extra oxygen atom in the oxazino[3,2-a]-ring of compounds 9–12 and 16– 19 may explain the increase in receptor binding for these compounds. Isobutyl 11 (pKi 10.3 ± 0.4) and cyclohexane sulfonamide 12 (pKi 9.7 ± 0.1) showed promising receptor binding. The inhibition activity on adenylyl cyclase for 10 and 11 were similar (pKb 9.7 ± 0.1–0.3), but lower for the cyclohexane sulfonamide 12 (pKb 8.0 ± 0.3). Also the benzodioxane sulfonamides 16–19 showed promising binding affinities in the nanomolar range. The synthesis of carboxylic acid esters 21–24 is outlined in Scheme 2 and the compounds shown in Table 2. Carboxylic acid derivatives 21–23 were prepared in acceptable yields by reductive amination of piperidine 20 with carbonyl compounds and sodium cyanoborohydride in methanol. Alkylation of piperidine 20 with methyl 2-[4-(bromomethyl)phenyl]propanoate and subsequent methyl ester hydrolysis afforded carboxylic acid 24. Cyclic carboxylic acids 21–23 were equipotent (pKi 8.8– 8.9 ± 0.0–0.1), while carboxylic acid 24 was more potent (pKi 9.5 ± 0.1, pKb-value of 8.8 ± 0.1). Finally, propanediol 25 was prepared in moderate yield by alkylating piperidine 20 with 3bromo-1,2-propanediol in ethanol at room temperature in presence of potassium carbonate as shown in Scheme 2. Propanediol 25 was a potent 5-HT4 receptor antagonist in the nanomolar range (pKi 10.1 ± 0.1, pKb-value of 9.1 ± 0.1). The promising binding data for N-aryl sulfonamides 4, 5, 9–12 and 16–19 as well as propanediol 25, may be explained by the lateral side chains and their capability of hydrogen bond interactions with a hydrophobic pocket in the 5-HT4 receptor.20,21 To assess the cardiotoxic potential of the new compounds, the reduction of hERG tail current of compounds 22, 24 and 25 was measured with the patch-clamp technique in HEK293 cells stably transfected with hERG ion channel cDNA. Peak hERG tail current amplitude was
5
determined prior to and following exposure to the compounds at different concentrations. Cyclohexanecarboxylic acid 22 had the lowest affinity for the hERG potassium channel (IC50 209 µM), followed by propanediol 25 (IC50 81 µM) and benzylic carboxylic acid 24 (IC50 25 µM). Unfortunately no N-aryl sulfonamides were investigated in this assay, but with a negative charge at physiological conditions due to acidic N-aryl sulfonamides, we would expect low hERG channel affinity for this group of 5-HT4 receptor antagonists as well. Literature references also indicate a correlation between lipophilicity and hERG activity, supporting our assumption that the acidic N-aryl sulfonamides 4, 5, 9–12 and 16–19 with log DOct7.4 values ranging from 0.5 to 2.5 will have reduced affinity for the hERG potassium channel.22 We have previously investigated the potential use of 5-HT4 receptor antagonists in heart failure treatment. Another promising therapeutic indication may be supraventricular tachycardia or arrhythmic conditions where rapid pharmacological onset of action is needed. Based on its overall biological and physiochemical properties, propanediol 25 was chosen for further pharmacokinetic investigations in male Sprague–Dawley rats; the results are outlined in Table 2. Propanediol 25 has low oral bioavailability but reaches plasma maximum fast. In summary, we have developed several hydrophilic 5-HT4 receptor antagonists with excellent receptor-binding properties. Carboxylic acids 22 and 24 are antagonists with low affinity for the hERG potassium channel. Finally, propanediol 25 is a potent 5-HT4 receptor antagonist with promising pharmacokinetic properties.
Conflict of interest Some of the compounds described in the present paper are described in WO2010112865 (Klaveness, J.; Brudeli, B.; Levy, F. O.; Moltzau, L. R.; Gulbrandsen, T.). This patent family is owned by Serodus ASA where Klaveness and Levy are shareholders.
6
Acknowledgements The authors wish to thank Drug Discovery Laboratory AS, Serodus ASA, The Research Council of Norway, The Norwegian Council on Cardiovascular Disease, The Kristian Gerhard Jebsen Foundation, Anders Jahre’s Foundation for the Promotion of Science and South-Eastern Norway Regional Health Authority for funding and support of this work.
1.
Hannon, J.; Hoyer, D. Behav. Brain Res. 2008, 195, 198.
2.
Bockaert, J.; Claeysen, S.; Compan, V.; Dumuis, A. Curr. Drug Targets: CNS Neurol. Disord. 2004, 3, 39.
3.
Bach, T.; Syversveen, T.; Kvingedal, A. M.; Krobert, K. A.; Brattelid, T.; Kaumann, A. J.; Levy, F. O. N-S. Arch. Pharmacol. 2001, 363, 146.
4.
Brattelid, T.; Kvingedal, A. M.; Krobert, K. A.; Andressen, K. W.; Bach, T.; Hystad, M. E.; Kaumann, A. J.; Levy, F. O. N-S. Arch. Pharmacol. 2004, 369, 616.
5.
Lezoulac’h, F.; Steplewski, K.; Sartiani, L.; Mugelli, A.; Fischmeister, R.; Bril, A. Biochem. Biophys. Res. Comm. 2007, 357, 218.
6.
Qvigstad, E.; Brattelid, T.; Sjaastad, I.; Andressen, K. W.; Krobert, K. A.; Birkeland, J. A.; Sejersted, O. M.; Kaumann, A. J.; Skomedal, T.; Osnes, J-B.; Levy, F. O. Cardiovasc. Res. 2005, 65, 869.
7.
Rahme, M. M.; Cotter, B.; Leistad, E.; Wadhwa, M. K.; Mohabir, R.; Ford, A. P.; Eglen, R. M.; Feld, G. K. Circulation 1999, 100, 2010.
8.
Birkeland, J. A. K.; Sjaastad, I.; Brattelid, T.; Qvigstad, E.; Moberg, E. R.; Krobert, K. A.; Bjørnerheim, R.; Skomedal, T.; Sejersted, O. M.; Osnes, J-B.; Levy, F. O. Br. J. Pharmacol. 2007, 150, 143.
9.
Gergs, U.; Baumann, M. Böckler, A.; Buchwalow, I. B.; Ebelt, H.; Fabritz, L.; Hauptmann, S.; Keller, N.; Kirchhof, P.; Klöckner, U.; Pönicke, K.; Rueckschloss, U.; Schmitz, W.; Werner, F.; Neumann, J. Am. J. Physiol. Heart Circ. Physiol. 2010, 299, H798.
10.
Kjekshus, J. K.; Torp-Pedersen, C.; Gullestad, L.; Køber, L.; Edvardsen, T.; Olsen, I. C.; Sjaastad, I.; Qvigstad, E.; Skomedal, T.; Osnes, J-B.; Levy, F. O. Eur. J. Heart Fail. 2009, 11, 771.
11.
Ponti, F. D.; Poluzzi, E.; Cavalli, A.; Recanatini, M.; Montanaro, N. Drug Saf. 2002, 25, 263.
12.
Choi, Y. J.; Seo, J. H.; Shin, K. J. Bioorg. Med. Chem. Lett. 2014, 24, 880.
13.
Gaster, L. M.; King, F. D. Med. Res. Rev. 1997, 17, 163.
14.
The amide carboxylic acid 4-[4-[(3,4-dihydro-2H-[1,3]oxazino[3,2-a]indole-10carbonylamino)methyl]-1-piperidinyl]-4-oxo-butanoic acid was prepared in our laboratory and is a low affinity 5-HT4 antagonist (pKi 7.3 ± 0.0, pKd 6.2 ± 0.0).
15.
Shen, F.; Smith, J. A.; Chang, R.; Bourdet, D. L.; Tsuruda, P. R.; Obedencio, G. P.; Beattie, D. T. Neuropharmacology 2011, 61, 69.
16.
Giannoni, P.; Gaven, F.; de Bundel, D.; Baranger, K.; Marchetti-Gauthier, E.; Roman, FS.; Valjent, E.; Marin, P.; Bockaert, J.; Rivera, S.; Claysen, S. Front Aging Neurosci. 2013, 5, 96.
7
17.
Brudeli, B.; Moltzau, L. R.; Andressen, K. W.; Krobert, K. A.; Klaveness, J.; Levy, F. O. Bioorg. Med. Chem. 2008, 18, 8600.
18.
Brudeli, B.; Moltzau, L. R.; Nguyen, C. H. T.; Andressen, K. W.; Nilsen, N. O.; Levy, F. O.; Klaveness, J. Eur. J. Med. Chem. 2013, 64, 629.
19.
Brudeli, B.; Andressen, K. W.; Moltzau, L. R.; Nilsen, N. O.; Levy, F. O.; Klaveness, J. Bioorg. Med. Chem. 2013, 21, 7134.
20.
Rivail, L.; Giner, M.; Gastineau, M.; Berthouze, M.; Soulier, J-L.; Fischmeister, R.; Lezoualc’h, F.; Maigret, B.; Sicsic, S.; Berque-Bestel, I. Br. J. Pharmacol. 2004, 143, 361.
21.
Schaus, J. M.; Thompson, D. C.; Bloomquist, W. E.; Susemichel, A. D.; Calligaro, D. O.; Cohen, M. I. J. Med. Chem. 1998, 41, 1943.
22.
Gleeson, M. P. J. Med. Chem. 2008, 51, 817.
8
GR113808
Figure 1. Representative 5-HT4 receptor antagonists.
SB207266
RO116-0367
a
b
1 (Ar = A) 6 (Ar = B) 13 (Ar = C)
2 (Ar = A) 7 (Ar = B) 14 (Ar = C)
3 (Ar = A) 8 (Ar = B) 15 (Ar = C)
c
(Ar = A) 4-5 9-12 (Ar = B) 16-19 (Ar = C)
Ar =
Ar = A
Ar = B
C
Scheme 1. Reagents and conditions: a) 4-nitrobenzyl bromide, K2CO3, acetone, reflux; b) H2 (atmospheric pressure), 10% Pd-C, MeOH, room temperature; c) RSO2Cl, CH2Cl2, pyridine, 0° C → room temperature.
a
21-23 d
b c 25
20
R2 = CH(CH3)CO2CH3 R2 = CH(CH3)CO2H
24
Scheme 2. Reagents and conditions: a) cyclic ketone, NaBH3CN, MeOH, room temperature; b) methyl 2-[4-(methylbromide)phenyl]propanoate, K2CO3, acetone, reflux; c) NaOH, MeOH/H2O, reflux; d) 3-bromo-1,2-propanediol, K2CO3, acetone, room temperature.
Table 1. Logarithmic permeation coefficients (log DOct7.4) from octanol/buffer distribution, binding properties at and antagonism of 5-HT-stimulated adenylyl cyclase via the 5-HT4(b) receptor of GR113808, SB207266, 4, 5, 9–16 and 17–19.
Ar =
Ar = A
a
Ar = B
C
Compound
Ar
R1
log DOct7.4 a
5-HT4(b)b
ACc
Formula
GR113808
—
—
—
9.6 ± 0.2
10.1 ± 0.2
C19H27N3O4S
SB207266
B
—
—
9.4 ± 0.3
10.5 ± 0.1
C22 H31N3O2
4
A
–Cyclohexane
0.5 ± 0.1
6.3 ± 0.3
—
C28H36N4O3S
5
A
–CH2Ph
1.2 ± 0.1
6.0 ± 0.3
—
C29H32N4O3S
9
B
–CH3
1.0 ± 0.1
9.7 ± 0.1
8.3 ± 0.2
C26H32N4O4S
10
B
–CH2CH2CH2CH3
2.2 ± 0.1
9.0 ± 0.6
9.7 ± 0.1
C29H38N4O4S
11
B
–CH2CH(CH3)2
2.2 ± 0.1
10.3 ± 0.4
9.7 ± 0.3
C29H38N4O4S
12
B
–Cyclohexane
2.7 ± 0.1
9.7 ± 0.1
8.0 ± 0.3
C31H40N4O4S
16
C
–CH3
0.5 ± 0.1
9.7 ± 0.1
8.3 ± 0.2
C23H29N3O5S
17
C
–CH2CH2CH2CH3
1.8 ± 0.1
9.6 ± 0.1
8.0 ± 0.2
C26H35N3O5S
18
C
–CH2CH(CH3)2
1.8 ± 0.1
9.7 ± 0.1
8.0 ± 0.3
C26H35N3O5S
19
C
–Cyclohexane
2.5 ± 0.1
8.9 ± 0.6
7.6 ± 0.2
C28H37N3O5S
Logarithmic distribution coefficient (log DOct7.4 ) from octanol/buffer distribution (mean ± SEM, n = 3). b pKi-values from competition of [3H]-GR113808 binding at the 5-HT4(b) receptor (mean ± SEM, n = 2–5). c pKb -
values from antagonism of 5-HT-stimulated adenylyl cyclase activity of the 5-HT4(b) receptor (mean ± SEM, n = 2–5)
Table 2. Logarithmic permeation coefficients (log DOct7.4) from octanol/buffer distribution, binding properties at and antagonism of 5-HT-stimulated adenylyl cyclase via the 5-HT4(b) receptor, inhibition of hERG potassium channel and pharmacokinetic (PK) data in rat of compounds 21–25.
log DOct7.4a
5-HT4(b) affinityb
ACc
hERGd
Formula
21
0.7 ± 0.1
8.8 ± 0.0
8.4 ± 0.1
—
C26H30N2O5
22
0.6 ± 0.2
8.9 ± 0.1
8.6 ± 0.1
209 µM
C24H30N2O5
23
0.6 ± 0.2
8.9 ± 0.0
8.6 ± 0.2
—
C25H32N2O5
Compound
R
a
24
–CH2C6H4CH(CH3)CO 2H
1.1 ± 0.2
9.5 ± 0.1
8.8 ± 0.1
25 µM
C28H32N2O5
25e
–CH2CH(OH)CH2 OH
0.2 ± 0.1
10.1 ± 0.1
9.1 ± 0.1
81 µM
C21H28N2O5
Logarithmic distribution coefficient (log DOct7.4 ) from octanol/buffer distribution (mean ± SEM, n = 3). b pKi-values from competition of [3H]-GR113808 binding at the 5-HT4(b) receptor (mean ± SEM, n = 2–5). c pKb -
values from antagonism of 5-HT-stimulated adenylyl cyclase activity of the 5-HT4(b) receptor (mean ± SEM, n = 2–5). d IC50 (n = 3). e PK data in rat of 25 (F = 10.3%, t1/2 = 150 min, Tmax = 145 min, n = 2).
5-HT4 receptor antagonist pKi 10.1, pKb 9.1 F 10.3%, hERG IC50 81µ µM
Graphical abstract
S0960-894X(14)00721-5 http://dx.doi.org/10.1016/j.bmcl.2014.06.083 BMCL 21802
To appear in:
Bioorganic & Medicinal Chemistry Letters
Received Date: Revised Date: Accepted Date:
29 May 2014 26 June 2014 28 June 2014
Please cite this article as: Brudeli, B., Navaratnarajah, M., Andressen, K.W., Manfra, O., Moltzau, L.R., Nilsen, N.O., Levy, F.O., Klaveness, J., Discovery and Pharmacological Profile of New Hydrophilic 5-HT4 Receptor Antagonists, Bioorganic & Medicinal Chemistry Letters (2014), doi: http://dx.doi.org/10.1016/j.bmcl.2014.06.083
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Discovery and Pharmacological Profile of New Hydrophilic 5-HT4 Receptor Antagonists
Bjarne Brudelia,d, Mirusha Navaratnarajah,b,d, Kjetil Wessel Andressenb,c, Ornella Manfrab,c, Lise Román Moltzaub,c, Nils Olav Nilsena, Finn Olav Levyb,c, Jo Klavenessd† a
Drug Discovery Laboratory AS, Oslo Innovation Center, N-0349 Oslo, Norway
b
Department of Pharmacology, Faculty of Medicine, University of Oslo and Oslo University Hospital, PO Box
1057 Blindern, N-0316 Oslo, Norway c
K.G. Jebsen Cardiac Research Centre and Center for Heart Failure Research, Faculty of Medicine, University
of Oslo, Norway d
Department of Medicinal Chemistry, School of Pharmacy, University of Oslo, N-0316 Oslo, Norway
†
Corresponding author: School of Pharmacy, University of Oslo, P.O. Box 1068 Blindern, N-0316 Oslo,
Norway. Phone: +47-22855043, Fax: +47-22857975, E-mail: [email protected]
Abstract The synthesis and pharmacological data of some new and potent hydrophilic 5-HT4 receptor antagonists are described. Propanediol derivative 25 was identified as a potent antagonist with low affinity for the hERG potassium channel and promising pharmacokinetics. Introduction Serotonin (5-hydroxytryptamine) is an important neurotransmitter and is a locally-acting signalling molecule in the human body. Serotonin is produced in enterochromaffin cells in the gastrointestinal tract; it is taken up, stored and released from blood platelets and is found in both the central and peripheral nervous system. The pharmacological action of serotonin is
1
mediated through seven different receptor subtypes (5-HT1-7), which are all G-coupled receptors, except the 5-HT3 receptor which is a ligand-gated ion channel.1 Several of the serotonin receptors are playing a role in various disorders, and recent investigations have brought new attention to the 5-HT4 receptor as a potential drug target in both the central nervous system (CNS) and in peripheral organs and tissues. The 5-HT4 receptor couples positively to adenylyl cyclase; activation of the receptor increases the intracellular cyclic AMP (cAMP) concentration, activates protein kinase A (PKA) and modulates intracellular responses. 2 Eleven different splice variants of the human 5-HT4 receptor are known today, at least four of them 5-HT4(a, b, g, i), are found in heart tissue.3,4 Increased expression of the 5-HT4(b) isoform in the atrium and left ventricle of chronic arrhythmic and failing hearts has recently been reported.5,6 The positive chronotropic and inotropic effect of serotonin through the 5-HT4 receptor may be deleterious in these conditions, and the use of 5-HT4 receptor antagonists in treatment of atrial fibrillation and heart failure has been evaluated in both animal models and humans.7,8,9,10 The potentially harmful cardiac effects of serotonin through the 5-HT4 receptor regarding atrial fibrillation and heart failure, and also the involvement of this receptor in aldosterone secretion, has made the 5-HT4 receptor a promising target of new and selective 5-HT4 receptor antagonists. Unfortunately, several drugs binding to serotonin receptors have shown low selectivity or affinity for the human ether-á-go-go-related gene (hERG) potassium ion channel, a tetrameric channel with six membrane-spanning domains, which has a crucial role in cardiac repolarization. Inhibition of this channel may cause prolongation of the cardiac action potential, reflected in the electrocardiogram as prolongation of the QT interval and predisposing to ventricular arrhythmias, also known as torsades de pointes (TdP). Cisapride, a partial 5-HT4 receptor agonist used to treat irritable bowel syndrome, was withdrawn from the market after several reports of drug-induced long QT syndrome.11
2
All new drug candidates should be screened for their ability to reduce hERG current in the early stage of lead discovery. Several drugs have affinity for this channel, but compounds with an alkaline nitrogen have a greater risk for binding to the hERG potassium ion channel. Several strategies are used to avoid hERG toxicity: reducing the alkalinity of nitrogen, lipophilicity and introduction of ionizable groups have been reported to reduce binding to the hERG potassium channel.12 The structural requirements of 5-HT4 receptor antagonists are well defined, and an aromatic moiety, followed by a hydrogen bond acceptor and an alkaline nitrogen atom are the cornerstones in the pharmacophore model.13 Replacing an amine with a corresponding amide is reported in the literature to mitigate hERG affinity for some T-type calcium channel blockers.12 This strategy is not possible for 5-HT4 receptor antagonists with the alkaline nitrogen as a major contributor to receptor binding, and an amide 5-HT4 antagonist with low receptor binding has previously been synthesized in our laboratory. 14 Reducing lipophilicity and creating zwitterions are however promising strategies for reducing the cardiotoxic potential of new drug candidates with effect on the serotonergic system. Recent studies suggest positive effects of 5-HT4 receptor agonists on cognitive and behavioural properties in animal models of Alzheimer’s disease, possibly through modulation of amyloidogenesis.15,16 It is therefore possible that 5-HT4 receptor antagonists which access the CNS can give undesirable side effects. We have previously reported 5-HT4 receptor antagonists with carboxylic acid groups as a promising strategy to minimize entrance into the central nervous system as well as reducing the affinity for the hERG potassium channel.17,18,19 In this letter we report some new promising acidic N-aryl sulfonamides and carboxylic acids as potent 5-HT4 receptor antagonists. This letter also describes a hydrophilic propandiol derivative with promising receptor binding and pharmacokinetic properties.
3
The starting materials N-(4-piperidinylmethyl)-1H-indole-3-carboxamide (1), N-(4piperidinylmethyl)-3,4-dihydro-2H-[1,3]oxazino[3,2-a]indole-10-carboxamide (6), N-(4piperidinylmethyl)-1,4-benzodioxane-5-carboxamide (13) and 4-piperidinylmethyl-3,4dihydro-2H-[1,3]oxazino[3,2-a]indole-10-carboxylate (20) were synthesized according to literature references.17,18,19 Binding affinities and 5-HT4 antagonist properties were determined for GR113808, SB207266 and compounds 4, 5, 9–12, 16–19 and 21–25 by competitive binding and concentration-dependent inhibition of 5-HT-stimulated adenylyl cyclase activity in membranes from HEK293 cells stably expressing the human 5-HT4(b) receptor. pKi and pKbvalues from competition of [3H]GR113808 binding and from antagonism of 5-HT4-stimulated adenylyl cyclase (AC) activity, respectively, for GR113808, SB207266 and compounds 4, 5, 9–12, 16–19 and 21–25 are summarized in Table 1 and 2. The synthesis of acidic N-aryl sulfonamide derivatives 4, 5, 9–12 and 16–19 are outlined in Scheme 1 and the compounds are shown in Table 1. Alkylation of aminopiperidines 1, 6 and 13 with 4-nitrobenzyl bromide in refluxing acetone in the presence of potassium carbonate afforded the aryl nitro intermediates 2, 7 and 14 in good yields. Reduction of the aryl nitro groups with hydrogen and palladium on activated carbon provided the N-aryl amines 3, 8 and 15. Finally, sulfonation of the corresponding N-aryl amines with different sulfonyl chlorides in a cooled mixture of dichloromethane and pyridine provided the N-aryl sulfonamides 4, 5, 9–12 and 16–19 in low to moderate yields. Cyclohexane 4 and benzyl sulfonamide 5 derivatives showed low binding affinities in the micromolar range. By introducing the oxazino[3,2-a]-ring to the indole skeleton, receptor binding was increased and we found that N-aryl sulfonamides 9–12 had potent binding affinities in the nanomolar range. The indole amides 4 and 5 have only one hydrogen bonding
4
position, while the extra oxygen atom in the oxazino[3,2-a]-ring of compounds 9–12 and 16– 19 may explain the increase in receptor binding for these compounds. Isobutyl 11 (pKi 10.3 ± 0.4) and cyclohexane sulfonamide 12 (pKi 9.7 ± 0.1) showed promising receptor binding. The inhibition activity on adenylyl cyclase for 10 and 11 were similar (pKb 9.7 ± 0.1–0.3), but lower for the cyclohexane sulfonamide 12 (pKb 8.0 ± 0.3). Also the benzodioxane sulfonamides 16–19 showed promising binding affinities in the nanomolar range. The synthesis of carboxylic acid esters 21–24 is outlined in Scheme 2 and the compounds shown in Table 2. Carboxylic acid derivatives 21–23 were prepared in acceptable yields by reductive amination of piperidine 20 with carbonyl compounds and sodium cyanoborohydride in methanol. Alkylation of piperidine 20 with methyl 2-[4-(bromomethyl)phenyl]propanoate and subsequent methyl ester hydrolysis afforded carboxylic acid 24. Cyclic carboxylic acids 21–23 were equipotent (pKi 8.8– 8.9 ± 0.0–0.1), while carboxylic acid 24 was more potent (pKi 9.5 ± 0.1, pKb-value of 8.8 ± 0.1). Finally, propanediol 25 was prepared in moderate yield by alkylating piperidine 20 with 3bromo-1,2-propanediol in ethanol at room temperature in presence of potassium carbonate as shown in Scheme 2. Propanediol 25 was a potent 5-HT4 receptor antagonist in the nanomolar range (pKi 10.1 ± 0.1, pKb-value of 9.1 ± 0.1). The promising binding data for N-aryl sulfonamides 4, 5, 9–12 and 16–19 as well as propanediol 25, may be explained by the lateral side chains and their capability of hydrogen bond interactions with a hydrophobic pocket in the 5-HT4 receptor.20,21 To assess the cardiotoxic potential of the new compounds, the reduction of hERG tail current of compounds 22, 24 and 25 was measured with the patch-clamp technique in HEK293 cells stably transfected with hERG ion channel cDNA. Peak hERG tail current amplitude was
5
determined prior to and following exposure to the compounds at different concentrations. Cyclohexanecarboxylic acid 22 had the lowest affinity for the hERG potassium channel (IC50 209 µM), followed by propanediol 25 (IC50 81 µM) and benzylic carboxylic acid 24 (IC50 25 µM). Unfortunately no N-aryl sulfonamides were investigated in this assay, but with a negative charge at physiological conditions due to acidic N-aryl sulfonamides, we would expect low hERG channel affinity for this group of 5-HT4 receptor antagonists as well. Literature references also indicate a correlation between lipophilicity and hERG activity, supporting our assumption that the acidic N-aryl sulfonamides 4, 5, 9–12 and 16–19 with log DOct7.4 values ranging from 0.5 to 2.5 will have reduced affinity for the hERG potassium channel.22 We have previously investigated the potential use of 5-HT4 receptor antagonists in heart failure treatment. Another promising therapeutic indication may be supraventricular tachycardia or arrhythmic conditions where rapid pharmacological onset of action is needed. Based on its overall biological and physiochemical properties, propanediol 25 was chosen for further pharmacokinetic investigations in male Sprague–Dawley rats; the results are outlined in Table 2. Propanediol 25 has low oral bioavailability but reaches plasma maximum fast. In summary, we have developed several hydrophilic 5-HT4 receptor antagonists with excellent receptor-binding properties. Carboxylic acids 22 and 24 are antagonists with low affinity for the hERG potassium channel. Finally, propanediol 25 is a potent 5-HT4 receptor antagonist with promising pharmacokinetic properties.
Conflict of interest Some of the compounds described in the present paper are described in WO2010112865 (Klaveness, J.; Brudeli, B.; Levy, F. O.; Moltzau, L. R.; Gulbrandsen, T.). This patent family is owned by Serodus ASA where Klaveness and Levy are shareholders.
6
Acknowledgements The authors wish to thank Drug Discovery Laboratory AS, Serodus ASA, The Research Council of Norway, The Norwegian Council on Cardiovascular Disease, The Kristian Gerhard Jebsen Foundation, Anders Jahre’s Foundation for the Promotion of Science and South-Eastern Norway Regional Health Authority for funding and support of this work.
1.
Hannon, J.; Hoyer, D. Behav. Brain Res. 2008, 195, 198.
2.
Bockaert, J.; Claeysen, S.; Compan, V.; Dumuis, A. Curr. Drug Targets: CNS Neurol. Disord. 2004, 3, 39.
3.
Bach, T.; Syversveen, T.; Kvingedal, A. M.; Krobert, K. A.; Brattelid, T.; Kaumann, A. J.; Levy, F. O. N-S. Arch. Pharmacol. 2001, 363, 146.
4.
Brattelid, T.; Kvingedal, A. M.; Krobert, K. A.; Andressen, K. W.; Bach, T.; Hystad, M. E.; Kaumann, A. J.; Levy, F. O. N-S. Arch. Pharmacol. 2004, 369, 616.
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Lezoulac’h, F.; Steplewski, K.; Sartiani, L.; Mugelli, A.; Fischmeister, R.; Bril, A. Biochem. Biophys. Res. Comm. 2007, 357, 218.
6.
Qvigstad, E.; Brattelid, T.; Sjaastad, I.; Andressen, K. W.; Krobert, K. A.; Birkeland, J. A.; Sejersted, O. M.; Kaumann, A. J.; Skomedal, T.; Osnes, J-B.; Levy, F. O. Cardiovasc. Res. 2005, 65, 869.
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Rahme, M. M.; Cotter, B.; Leistad, E.; Wadhwa, M. K.; Mohabir, R.; Ford, A. P.; Eglen, R. M.; Feld, G. K. Circulation 1999, 100, 2010.
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Birkeland, J. A. K.; Sjaastad, I.; Brattelid, T.; Qvigstad, E.; Moberg, E. R.; Krobert, K. A.; Bjørnerheim, R.; Skomedal, T.; Sejersted, O. M.; Osnes, J-B.; Levy, F. O. Br. J. Pharmacol. 2007, 150, 143.
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Gergs, U.; Baumann, M. Böckler, A.; Buchwalow, I. B.; Ebelt, H.; Fabritz, L.; Hauptmann, S.; Keller, N.; Kirchhof, P.; Klöckner, U.; Pönicke, K.; Rueckschloss, U.; Schmitz, W.; Werner, F.; Neumann, J. Am. J. Physiol. Heart Circ. Physiol. 2010, 299, H798.
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Kjekshus, J. K.; Torp-Pedersen, C.; Gullestad, L.; Køber, L.; Edvardsen, T.; Olsen, I. C.; Sjaastad, I.; Qvigstad, E.; Skomedal, T.; Osnes, J-B.; Levy, F. O. Eur. J. Heart Fail. 2009, 11, 771.
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Ponti, F. D.; Poluzzi, E.; Cavalli, A.; Recanatini, M.; Montanaro, N. Drug Saf. 2002, 25, 263.
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Choi, Y. J.; Seo, J. H.; Shin, K. J. Bioorg. Med. Chem. Lett. 2014, 24, 880.
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Gaster, L. M.; King, F. D. Med. Res. Rev. 1997, 17, 163.
14.
The amide carboxylic acid 4-[4-[(3,4-dihydro-2H-[1,3]oxazino[3,2-a]indole-10carbonylamino)methyl]-1-piperidinyl]-4-oxo-butanoic acid was prepared in our laboratory and is a low affinity 5-HT4 antagonist (pKi 7.3 ± 0.0, pKd 6.2 ± 0.0).
15.
Shen, F.; Smith, J. A.; Chang, R.; Bourdet, D. L.; Tsuruda, P. R.; Obedencio, G. P.; Beattie, D. T. Neuropharmacology 2011, 61, 69.
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Giannoni, P.; Gaven, F.; de Bundel, D.; Baranger, K.; Marchetti-Gauthier, E.; Roman, FS.; Valjent, E.; Marin, P.; Bockaert, J.; Rivera, S.; Claysen, S. Front Aging Neurosci. 2013, 5, 96.
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Brudeli, B.; Moltzau, L. R.; Andressen, K. W.; Krobert, K. A.; Klaveness, J.; Levy, F. O. Bioorg. Med. Chem. 2008, 18, 8600.
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Brudeli, B.; Moltzau, L. R.; Nguyen, C. H. T.; Andressen, K. W.; Nilsen, N. O.; Levy, F. O.; Klaveness, J. Eur. J. Med. Chem. 2013, 64, 629.
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Brudeli, B.; Andressen, K. W.; Moltzau, L. R.; Nilsen, N. O.; Levy, F. O.; Klaveness, J. Bioorg. Med. Chem. 2013, 21, 7134.
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Rivail, L.; Giner, M.; Gastineau, M.; Berthouze, M.; Soulier, J-L.; Fischmeister, R.; Lezoualc’h, F.; Maigret, B.; Sicsic, S.; Berque-Bestel, I. Br. J. Pharmacol. 2004, 143, 361.
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Schaus, J. M.; Thompson, D. C.; Bloomquist, W. E.; Susemichel, A. D.; Calligaro, D. O.; Cohen, M. I. J. Med. Chem. 1998, 41, 1943.
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Gleeson, M. P. J. Med. Chem. 2008, 51, 817.
8
GR113808
Figure 1. Representative 5-HT4 receptor antagonists.
SB207266
RO116-0367
a
b
1 (Ar = A) 6 (Ar = B) 13 (Ar = C)
2 (Ar = A) 7 (Ar = B) 14 (Ar = C)
3 (Ar = A) 8 (Ar = B) 15 (Ar = C)
c
(Ar = A) 4-5 9-12 (Ar = B) 16-19 (Ar = C)
Ar =
Ar = A
Ar = B
C
Scheme 1. Reagents and conditions: a) 4-nitrobenzyl bromide, K2CO3, acetone, reflux; b) H2 (atmospheric pressure), 10% Pd-C, MeOH, room temperature; c) RSO2Cl, CH2Cl2, pyridine, 0° C → room temperature.
a
21-23 d
b c 25
20
R2 = CH(CH3)CO2CH3 R2 = CH(CH3)CO2H
24
Scheme 2. Reagents and conditions: a) cyclic ketone, NaBH3CN, MeOH, room temperature; b) methyl 2-[4-(methylbromide)phenyl]propanoate, K2CO3, acetone, reflux; c) NaOH, MeOH/H2O, reflux; d) 3-bromo-1,2-propanediol, K2CO3, acetone, room temperature.
Table 1. Logarithmic permeation coefficients (log DOct7.4) from octanol/buffer distribution, binding properties at and antagonism of 5-HT-stimulated adenylyl cyclase via the 5-HT4(b) receptor of GR113808, SB207266, 4, 5, 9–16 and 17–19.
Ar =
Ar = A
a
Ar = B
C
Compound
Ar
R1
log DOct7.4 a
5-HT4(b)b
ACc
Formula
GR113808
—
—
—
9.6 ± 0.2
10.1 ± 0.2
C19H27N3O4S
SB207266
B
—
—
9.4 ± 0.3
10.5 ± 0.1
C22 H31N3O2
4
A
–Cyclohexane
0.5 ± 0.1
6.3 ± 0.3
—
C28H36N4O3S
5
A
–CH2Ph
1.2 ± 0.1
6.0 ± 0.3
—
C29H32N4O3S
9
B
–CH3
1.0 ± 0.1
9.7 ± 0.1
8.3 ± 0.2
C26H32N4O4S
10
B
–CH2CH2CH2CH3
2.2 ± 0.1
9.0 ± 0.6
9.7 ± 0.1
C29H38N4O4S
11
B
–CH2CH(CH3)2
2.2 ± 0.1
10.3 ± 0.4
9.7 ± 0.3
C29H38N4O4S
12
B
–Cyclohexane
2.7 ± 0.1
9.7 ± 0.1
8.0 ± 0.3
C31H40N4O4S
16
C
–CH3
0.5 ± 0.1
9.7 ± 0.1
8.3 ± 0.2
C23H29N3O5S
17
C
–CH2CH2CH2CH3
1.8 ± 0.1
9.6 ± 0.1
8.0 ± 0.2
C26H35N3O5S
18
C
–CH2CH(CH3)2
1.8 ± 0.1
9.7 ± 0.1
8.0 ± 0.3
C26H35N3O5S
19
C
–Cyclohexane
2.5 ± 0.1
8.9 ± 0.6
7.6 ± 0.2
C28H37N3O5S
Logarithmic distribution coefficient (log DOct7.4 ) from octanol/buffer distribution (mean ± SEM, n = 3). b pKi-values from competition of [3H]-GR113808 binding at the 5-HT4(b) receptor (mean ± SEM, n = 2–5). c pKb -
values from antagonism of 5-HT-stimulated adenylyl cyclase activity of the 5-HT4(b) receptor (mean ± SEM, n = 2–5)
Table 2. Logarithmic permeation coefficients (log DOct7.4) from octanol/buffer distribution, binding properties at and antagonism of 5-HT-stimulated adenylyl cyclase via the 5-HT4(b) receptor, inhibition of hERG potassium channel and pharmacokinetic (PK) data in rat of compounds 21–25.
log DOct7.4a
5-HT4(b) affinityb
ACc
hERGd
Formula
21
0.7 ± 0.1
8.8 ± 0.0
8.4 ± 0.1
—
C26H30N2O5
22
0.6 ± 0.2
8.9 ± 0.1
8.6 ± 0.1
209 µM
C24H30N2O5
23
0.6 ± 0.2
8.9 ± 0.0
8.6 ± 0.2
—
C25H32N2O5
Compound
R
a
24
–CH2C6H4CH(CH3)CO 2H
1.1 ± 0.2
9.5 ± 0.1
8.8 ± 0.1
25 µM
C28H32N2O5
25e
–CH2CH(OH)CH2 OH
0.2 ± 0.1
10.1 ± 0.1
9.1 ± 0.1
81 µM
C21H28N2O5
Logarithmic distribution coefficient (log DOct7.4 ) from octanol/buffer distribution (mean ± SEM, n = 3). b pKi-values from competition of [3H]-GR113808 binding at the 5-HT4(b) receptor (mean ± SEM, n = 2–5). c pKb -
values from antagonism of 5-HT-stimulated adenylyl cyclase activity of the 5-HT4(b) receptor (mean ± SEM, n = 2–5). d IC50 (n = 3). e PK data in rat of 25 (F = 10.3%, t1/2 = 150 min, Tmax = 145 min, n = 2).
5-HT4 receptor antagonist pKi 10.1, pKb 9.1 F 10.3%, hERG IC50 81µ µM
Graphical abstract
