Identification of aryl sulfonamides as novel and potent inhibitors of NaV1.5

Article abstract of DOI:10.1016/j.bmcl.2021.128133

We describe the synthesis and biological evaluation of a series of novel aryl sulfonamides that exhibit potent inhibition of Na_V1.5. Unlike local anesthetics that are currently used for treatment of Long QT Syndrome 3 (LQT-3), the most potent compound (-)-6 in this series shows high selectivity over hERG and other cardiac ion channels and has a low brain to plasma ratio to minimize CNS side effects. Compound (-)-6 is also effective in shortening prolonged action potential durations (APDs) in a pharmacological model of LQT-3 syndrome in pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). Unlike most aryl sulfonamide Na_V inhibitors that bind to the channel voltage sensors, these Na_V1.5 inhibitors bind to the local anesthetic binding site in the central pore of the channel.

Full text of DOI:10.1016/j.bmcl.2021.128133

Bioorg. Med. Chem. Lett. 45 (2021) 128133
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Identification of aryl sulfonamides as novel and potent inhibitors of NaV1.5
Shaoyi Sun*, Qi Jia, Alla Y. Zenova, Sophia Lin, Angela Hussainkhel, Janette Mezeyova,
Elaine Chang, Samuel J. Goodchild, Zhiwei Xie, Andrea Lindgren, Gina de Boer, Rainbow Kwan,
Kuldip Khakh, Luis Sojo, Paul Bichler, J.P. Johnson Jr., James R. Empfield, Charles J. Cohen,
Christoph M. Dehnhardt, Richard Dean
Xenon Pharmaceuticals Inc., 200-3650 Gilmore Way, Burnaby, BC V5G 4W8, Canada
A R T I C L E I N F O
A B S T R A C T
Keywords:
We describe the synthesis and biological evaluation of a series of novel aryl sulfonamides that exhibit potent
inhibition of NaV1.5. Unlike local anesthetics that are currently used for treatment of Long QT Syndrome 3 (LQT-
3), the most potent compound (-)-6 in this series shows high selectivity over hERG and other cardiac ion channels
and has a low brain to plasma ratio to minimize CNS side effects. Compound (-)-6 is also effective in shortening
prolonged action potential durations (APDs) in a pharmacological model of LQT-3 syndrome in pluripotent stem
cell-derived cardiomyocytes (iPSC-CMs). Unlike most aryl sulfonamide NaV inhibitors that bind to the channel
voltage sensors, these NaV1.5 inhibitors bind to the local anesthetic binding site in the central pore of the
channel.
Aryl sulfonamide
NaV1.5
Cardiac arrhythmia
LQT-3
The cardiac voltage-gated sodium channel NaV1.5 (SCN5A gene) is
expressed mainly in the cell membrane of cardiomyocytes, including the
sarcolemma of atrial and ventricular myocytes, Purkinje fibers, sino-
atrial, and atrio-ventricular nodes.1 The rapid upstroke of the cardiac
action potential and the rapid impulse conduction through cardiac tissue
is due to sodium influx via NaV1.5 channels. Mutations in the SCN5A
gene result in the genesis of a variety of cardiac arrhythmias. Hundreds
of unique SCN5A mutations have been identified in patients, with the
vast majority being in two primary inherited cardiomyopathies, either
long QT syndrome type 3 (LQT-3, gain-of-function)2–5 or Brugada syn-
drome (BrS, loss-of-function).6 In addition, SCN5A mutations have also
been reported in association with other cardiac disorders, including sick
sinus syndrome,7 atrial standstill,8 cardiac conduction defect (CCD),9
atrial fibrillation (AF),10,11 and dilated cardiomyopathy (DCM).12
Sodium channel blocker therapy has been extensively used in treat-
ing cardiac arrhythmias, with many therapeutically useful anti-
arrhythmic agents targeting NaV1.5 (e.g. local anesthetics such as
mexiletine 1).13 Although these drugs are widely used, they suffer from
dose-limiting adverse effects, especially nausea and dizziness.14 Rano-
lazine (2), structurally similar to other class I anti-arrhythmic agents, is
currently marketed for the treatment of chronic angina. Although the
mechanism of its antianginal effects is not known, 2 does inhibit NaV1.5,
and has significant anti-arrhythmic effects in both ventricles and atria.
Unfortunately, 2 blocks β-adrenergic receptors, and inhibits a number of
̀
cardiac ion currents (e.g., human ether-a-go-go-related gene,
hERG).15,16 A more potent compound, GS-967 (3), was found to have
high brain penetration and high activity on brain sodium channel iso-
forms (e.g., NaV1.1, NaV1.2, & NaV1.6).17 Eleclazine (4), purportedly
selective over brain sodium channel isoforms, was discontinued from
clinical development.18
In an effort to identify structurally distinct NaV1.5 inhibitors with
high selectivity over hERG and limited brain exposure, the corporate
compound repository was surveyed. Aryl sulfonamide rac-5 was found
to be a modest NaV1.5 inhibitor. We were intrigued by its structural
feature because aryl sulfonamide is a well-known structure for subtype
selective inhibitors of NaV1.7 and, in general, displays low hERG activity
and low central nervous system (CNS) penetration. Herein, we describe
our efforts in the optimization of rac-5 that led to the identification of a
series of novel NaV1.5 inhibitors including (-)-6, a potent NaV1.5 in-
hibitor with high selectivity over hERG and other cardiac ion channels
and low brain penetration.
The synthesis of these aryl sulfonamides is exemplified by rac-6 as
illustrated in Scheme 1, in general, via a SNAr reaction joining a 3-
substituted piperidin-4-ol left-hand fragment (LHF) with a suitably
protected heteroaryl sulfonamide right-hand fragment (RHF) through
an oxygen linkage. Construction of the LHF (rac-11) was commenced by
* Corresponding author.
E-mail address: ssun@xenon-pharma.com (S. Sun).
https://doi.org/10.1016/j.bmcl.2021.128133
Received 7 April 2021; Received in revised form 11 May 2021; Accepted 19 May 2021
Available online 24 May 2021
0960-894X/© 2021 Elsevier Ltd. All rights reserved.

S. Sun et al.
Bioorganic & Medicinal Chemistry Letters 45 (2021) 128133
Suzuki-Miyaura cross-coupling reaction of vinylboronic acid pinacol
ester 7 with 4-bromo-1,2-difluorobenzene to form 8. Conversion of 8 to
rac-10 was initially carried out by hydroboration-oxidation method.19
This method, however, only produced rac-10 in 15% yield. Therefore,
we investigated different approaches and found an efficient method for
preparation of rac-10. To this end, we carried out an epoxidation of 8
using m-CPBA and subsequent hydrogenation of epoxide rac-9 using
molybdenum-promoted (1 wt%) nickel (skeletal) as the catalyst to
provide rac-10 in 56% yield over two steps. To our knowledge, this
represents the first example of stereoselective preparation of a trans
cyclic alcohol via metal-catalyzed reduction of an epoxide. In contrast,
when Pd/C was used as the catalyst in this reaction, only the cis-isomer
was isolated. With an efficient access to rac-10 at hand, we were now in
a position to complete the synthesis of the key intermediate rac-11.
Treatment of rac-10 with methanolic HCl, followed by alkylation with
2,2,2-trifluoroethyl trifluoromethanesulfonate under basic conditions
provided intermediate rac-11. The RHF 15 was built by addition of aryl
sulfonyl chloride 14 to the 2,4-dimethoxybenzyl (DMB) protected 2-
amino 6-fluoropyridine intermediate 1320 in the presence of a base.
Finally, NaH-mediated SNAr reaction of rac-11 and 15, and subsequent
TFA cleavage of the DMB protecting group of rac-12 completed the
synthesis of compound rac-6.
brief SAR investigation on rac-23 was executed; the results are shown in
Table 1. Shifting the fluorine from the 6-position to the 3- or 5-position,
as in rac-24 and rac-26, resulted in a significant decrease in activity.
However, 4-fluoropyridine analog rac-25 maintained similar potency to
rac-23. Replacing the 6-fluoropyridine in rac-23 with 6-chloropyridine
(rac-27) also maintained the inhibitory activity, while a significant
decrease in potency was observed with 6-trifluoromethyl pyridine
analog (rac-28).
Given its improved potency of hNaV1.5 inhibition compared to rac-5,
the pyridyl analogue rac-23 was taken as an advanced lead for further
optimization. Related SAR is summarized in Table 2. Incorporation of
fluorine at either the 3- (rac-30) or 4-position (rac-31) of the left-hand
phenyl ring resulted in only a small improvement in potency and
metabolic stability, while 2-fluorine (rac-29) had no effect. Fluorination
of both the 3- and 4- positions proved effective, as rac-33 was about 2-
fold more potent than rac-23 and displayed improved metabolic sta-
bility. Polar substitutions on the left-hand phenyl ring were not toler-
ated, for example a nitrile group in rac-34 resulted in a significant loss in
hNaV1.5 potency, while the complete lack of activity of the methyl-
sulfonyl analog rac-35 was quite striking.
Compound rac-33 showed an attractive profile due to good hNaV1.5
potency and in vitro microsomal stability. Therefore, we decided to study
this compound further. The optically pure enantiomers were obtained
by chiral separation and evaluated individually; however, the absolute
stereochemistry could not be determined readily, and instead the fir2s1t
Taking rac-5 as a starting point, our initial structure–activity rela-
tionship (SAR) studies focused on replacing the 1,2,4-thiadiazole moiety
in rac-5 to improve NaV1.5 potency, and investigating different five- and
six-membered nitrogen-containing heterocycles. This effort provided us
several compounds with improved hNaV1.5 activity relative to rac-5: the
eluting enantiomer from the chiral column was assigned as (-)-33 ([α]
D
= -18.90, c 2.1, DMF) and the second eluting enantiomer was assigned as
21
4-thiazole rac-17 (IC50 = 1.18
μ
M) and 6-fluoropyridine rac-23 (IC50
=
(+)-33 ([
α
]
D
= +18.74, c 2.1, DMF). (-)-33 was slightly more potent
0.70 M) were revealed to be the two most potent hNaV1.5 inhibitors. A
μ
with an IC50 value of 0.24 μM on hNaV1.5.
Scheme 1. Preparation and chiral separation of compound rac-6. Reagents and conditions: (i) 4-bromo-1,2-difluorobenzene, K2CO3, Pd(PPh3)4, 1,4-dioxane, H2O,
90 ◦C, 18 h, 94%. (ii) BH3⋅THF, THF, 0 ◦C to rt, 3 h then NaBO3⋅4H2O, 0 ◦C to rt, 16 h, 15%. (iii) m-CPBA, CH2Cl2, 0 ◦C to rt, 14 h, 82%. (iv) Molybdenum promoted
(1 wt%) nickel (skeletal), methanol, 50 psi H2, rt, 7 h, 69%. (v) 4 M HCl-MeOH, rt, 0.5 h; K2CO3, 2,2,2-trifluoroethyl trifluoromethanesulfonate, CH3CN, rt, 14 h,
82%. (vi) 15, NaH, DMF, 0 ◦C to rt, 18 h. (vii) TFA, CH2Cl2, 0 ◦C to rt, 1 h, 60% in 2 steps. (viii) Chiral SFC. (ix) MeLi, THF, ꢀ 78 ◦C to rt, 15 min., then 14, ꢀ 78 ◦C to rt
1.5 h, 84%.
2

S. Sun et al.
Bioorganic & Medicinal Chemistry Letters 45 (2021) 128133
Table 1
Table 2
NaV1.5
activity
of
compounds
rac-5,
and
rac-16
–
rac-
NaV1.5 activity and metabolic stability of compounds rac-23, and rac-29 – rac-
38.
28.
Compounda
Ar
X
Y
HET
hNaV1.5
IC50
HLM,
MLM
Compda
Het
hNaV1.5
Compda
Het
hNaV1.5
(
μ
M) b
CLhep
(mL/min/
kg)
IC50
(
μ
M) b
IC50
(
μ
M) b
rac-5
7.83
rac-16
25.05
rac-23
C
C
0.70
16, 70
(F)
(H)
rac-17
rac-19
rac-21
rac-23
1.18
7.14
rac-18
rac-20
rac-22
rac-24
4.65
>30
4.32
5.04
rac-29
rac-30
rac-31
C
C
0.68
0.46
0.61
17, 71
13, 53
11, 62
(F)
(H)
25.49
0.70
C
C
(F)
(H)
C
C
(F)
(H)
rac-25
rac-27
1.29
1.10
rac-26
rac-28
13.21
6.33
rac-32
rac-33
C
C
0.47
0.26
13, 49
7.5, 49
(F)
(H)
a
All compounds exhibited spectral data consistent with their proposed
C
C
structures and had analytical purities >94% as determined by HPLC.
(F)
(H)
b
IC50s were an average of at least two independent determinations using
automated voltage clamp electrophysiology.
(-)–33
(+)–33
rac-34
enantiomer 1
enantiomer 2
0.24
0.43
4.58
9.0, 50
7.0, 45
ndc
We subsequently discovered analog rac-6, which was about 4-fold
more potent than rac-33. However, this improvement came at the cost
of lower microsomal stability. We postulated that the increased meta-
bolic clearance of rac-6 might be due to the absence of the 2-fluoro
substituent of the central phenyl ring; disappointingly, addition of a 2-
fluorine in rac-36 did not lead to improvement in metabolic stability.
Furthermore, replacement of the central phenyl ring with a pyridyl ring,
compound rac-37, displayed similar metabolic stability as rac-33, but
with erosion of hNaV1.5 activity. For comparison, the 4-thiazole analog
rac-38 was also prepared and found to be not as efficient as its 6-fluoro-
pyridine counterpart rac-33 in NaV1.5 inhibition and metabolic stabil-
ity, consistent with the earlier SAR.
C
C
(F)
(H)
rac-35
rac-6
C
C
>30
ndc
(F)
(H)
C
C
0.065
15, 65
(H)
(F)
(-)-6
enantiomer 1
enantiomer 2
0.039
0.17
13, 63
14, 74
14, 65
(+)-6
rac-36
C
C
0.031
Chiral separation of rac-6 provided two optically pure enantiomers
(F)
(F)
(-)-6 ([
α]
21 = -7.95, c 2.1, DMF) and (þ)-6 ([
α
]
D
21 = +7.52, c 2.1, DMF).
(-)-6 wasDabout 4-fold more potent than (+)-6 with an IC50 value of
rac-37
rac-38
C
N
1.55
0.75
8.4, 63
14, 70
0.039 μM on hNaV1.5. Further evaluation of (-)-6 suggested that (-)-6
(H)
had 16-, 7-, and 6-fold selectivity over CNS sodium channel isoforms
hNaV1.1, 1.2, and 1.6 (IC50s of 0.62, 0.27, and 0.23 µM, respectively.),
when measured by whole cell voltage clamp (EP). The EP protocol used
to optimize potency on NaV1.5 was designed to maximize interaction
with the high affinity state of the channel and best approximate the Kd
for binding to NaV1.5, especially for potent compounds that have slow
kinetics of binding equilibration. We have found that using this protocol
for selectivity assessments can overestimate the true selectivity of
compounds that have differentiated rates of equilibrium with distinct
channel isoforms. For this reason, we also measured compound isoform
C
C
(F)
(H)
a
All compounds exhibited spectral data consistent with their proposed
structures and had analytical purities >94% as determined by HPLC.
b
IC50s were an average of at least two independent determinations using
automated voltage clamp electrophysiology.
c
nd: not determined.
selectivity with a different (V ) protocol that we believe better assesses
½
the physiologically relevant selectivity. In this selectivity protocol, po-
tency (IC50) on hNaV1.5, 1.1, 1.2, 1.6 changed to 0.11, 0.09, 0.012, and
0.11 µM, respectively, suggesting that the apparent selectivity seen in
the SAR protocol is not likely to translate to an in vivo setting.
Compound (-)-6 was also evaluated in a sodium influx assay21 for its
inhibitory activities on hNaV1.5, 1.1, 1.2, 1.6 and 1.7, and exhibited IC50
values of 0.044, 0.56, 0.27, 0.11, and 0.22 µM, respectively.
Compounds (-)-33 and (-)-6 were found to have negligible inhibition
on CYPs 1A2, 3A4, 2C19, 2D6, and moderate inhibition on CYP2C9
(IC50s of 6.9, and 2.2 μM for (-)-33 and (-)-6, respectively.). Importantly,
(-)-6 was highly selective, when tested by voltage clamp against a panel
of heterologously expressed cardiac ion channels including hERG,
KV2.1, KV1.5, KV3.2, HCN2, HCN4, KV4.2KChIP2.2, KV4.3KChIP2.2,
3

S. Sun et al.
Bioorganic & Medicinal Chemistry Letters 45 (2021) 128133
KVLQT1/mink, CaV1.2, CaV2.2, CaV3.1, CaV3.3, GABA, TRPV1, and 5-
HT3A. For example, (-)-6 showed 5% inhibition on hERG at 10 μM
concentration.
The pharmacokinetic (PK) properties of (-)–33 and (-)-6 were
determined in mouse (Table 3). Consistent with the predicted CLhep and
high plasma protein binding (99.8% bound), both compounds exhibited
low plasma clearance (CL), moderate terminal half-lives (t ) and low
½
volume of distribution (Vss). The oral bioavailability of (-)–33 and (-)-6
were 45%, and 39%, respectively. In addition, both (-)–33 and (-)-6
exhibited low brain levels, suggesting that the activity on CNS sodium
channel isoforms was not a concern.
Next, we evaluated the activity of (-)-6 in shortening prolonged ac-
tion potential durations (APDs) like those often observed in long QT
syndrome-3 (LQT-3) patients carrying gain-of-function SCN5A muta-
tions. The Anemonia sulcata toxin II (ATX-II) is known to slow the
inactivation of NaV1.522, thereby increasing total sodium flux and
simulating a gain-of-function SCN5A mutation that causes a persistent
sodium current, which would lead to a prolongation of the APD. In this
study we used an ATX-II-induced model of prolonged APD in human
induced pluripotent stem cell cardiomyocytes (iPSC-CMs) utilizing
current clamp to record the APD of spontaneously beating iPSC-CMs.
Only cells with maximum diastolic potentials
<
-75 mV and
ventricular-like AP morphology (upstroke velocity > 70 V/s) were used.
With the addition of 15–30 nM ATX-II, prolongation of the APD was
observed in the iPSC-CMs with a 25–100% increase in APD90, depending
on the sensitivity of the cell (Fig. 2). Addition of 100 nM (-)-6 (2.5 ×
NaV1.5 IC50) concurrently with ATX-II shortened the ATX-II-induced
prolongation by 84%, returning it close to vehicle. Compound (-)-6
showed no effect on AP amplitude or maximum diastolic membrane
potential (Fig. S2A in supplementary data), however, it did cause a small
reduction in upstroke velocity dV/dt(Vmax) of 23% (Fig. S2B in sup-
plementary data).
Fig. 1. Selected NaV1.5 inhibitors and compounds rac-5 and (-)-6.
potential of a cardiomyocyte, rather than selective block of late INa as
(-)-6 had a reduction in prolonged APD yet no peak/late selectivity.
To investigate the binding mode of NaV1.5 inhibition, we performed
mutagenesis studies using compounds rac-17 and rac- 23 (Table 4).
Recently, subtype-selective aryl sulfonamide NaV inhibitors with an
anionic warhead have been shown to bind to a positively charged gating
residue, the fourth Arg in segment S4 (R4) in the NaV1.7 voltage sensor
of domain IV (VSD4).24,25 Therefore, we evaluated the binding of
compounds rac-17 and rac-23 on the equivalent VSD4 R1631A (R4A)
mutation in NaV1.5 using the VSD4 blocker GX-419525 as a control. This
mutant led to more than 18-fold decrease in NaV1.5 potency for GX-
4195, however, no clear potency drop was observed for rac-17 or rac-
23, suggesting that rac-17 and rac-23 do not have interactions with the
positively charged gating residue (R4) in VSD4. Furthermore, rac-23
was also evaluated on VSD4 R1622A (R1A), R1625A (R2A), R1628A
(R3A) and R1634A (R5A) mutants to determine if it engaged any of the
other highly conserved arginines in VSD4. Again, no clear potency
It has been reported that mexiletine (1), ranolazine (2), GS-967 (3)
and eleclazine (4) inhibit the NaV1.5 late (persistent) current (INa
)
(Fig. 1), which is enhanced in LQT3 patients and other cardiac patho-
logical conditions, such as ischemic heart disease.13,17,18 By blocking the
late sodium current during ischemia, these drugs inhibit the subsequent
sodium-calcium overload within the myocyte that is normally a hall-
mark of an ischemic cell.23 We therefore determined the selectivity of
(-)-6 for inhibiting the NaV1.5 late INa over the NaV1.5 peak INa. Anal-
ogous to the iPSC experiment, ATX-II was used to generate NaV1.5 late
INa in HEK cells stably expressing hNaV1.5 and both peak and late
NaV1.5 currents were measured at a holding potential of ꢀ 95 mV,
similar to the resting membrane potential of the iPSC cardiomyocytes.
Unfortunately, the ratio of IC50 values for inhibition of peak and late INa
by (-)-6 was only 1.1-fold (peak/late IC50 17.7/15.8 nM). This suggests
that in the ATX-II-induced iPSC model at least, it appears that the effi-
cacy is mainly driven by total NaV1.5 inhibition at the resting membrane
change was observed (IC50s of 1.29, 0.81, 0.82 and 1.21 μM, respec-
tively). We next hypothesized that this class of compounds might be
binding to a corresponding conserved arginine in VSD2 instead of R4 in
VSD4, thereby imparting its inhibitory activity through VSD2, similar to
the peptide toxin ProTx-II.26 We evaluated rac-23 on a VSD2 R814A
(R3A) mutant, which corresponds to R4 in VSD4, but saw no clear
impact of the mutation (IC50 of 0.41 μM).
We continued to investigate the binding site for this class of com-
pounds by site directed mutagenesis of phenylalanine 1759 to alanine
(F1759A) in the pore domain of the NaV1.5 channel followed by func-
tional analysis. This residue, found in VSD4-S6, is known to be essential
for binding of some antiarrhythmic agents, such as ranolazine,27 in
addition to the local anesthetics (e.g., lidocaine).28 The potency of (-)–
Table 3
PK profiles of compounds (-)–33 and (-)-6a.
Compound
(-)–33
(-)-6
iv
CL (mL/min/kg)
1.8
4.3
0.6
16
3.8
2.6
0.8
7.6
t
½
(h)
33 for the mutated channel was reduced by>40-fold (IC50 > 10 μM),
Vss (L/Kg)
AUC (µM.h)
po
suggesting that these aryl sulfonamide NaV1.5 inhibitors bind to the
local anesthetic binding site in the pore domain.
C
max (µM)
5.2
3.6
We further tested the ability of compounds (-)–33 and (-)-6 to
displace the [3H]BNZA ligand. This ligand has been shown to bind to the
pore of NaV1.5 and most clinical local anesthetics inhibit binding of [3H]
BNZA.29 This was also the case for (-)–33 and (-)-6 with Ki values of 2.02
and 0.37 µM, respectively. Furthermore, in voltage clamp studies of
NaV1.5 expressed heterologously in HEK cells, the state-dependence of
block for (-)-6, was only 24-fold when comparing the shift in IC50 at
t
½
(h)
4.1
2.7
AUC (µM.h)
72
30
F (%)
45
39
Cb/Cp @ 2 h (µM) (ratio)
2.62/9.37 (0.28)
2.03/6.44 (0.32)
a
Average of 3 male FVB mice. Intravenous dosed with 1 mg/kg of compound
(-)–33 or (-)-6 in PEG400 and 50% 2-Hydroxypropyl-β-cyclodextrin in saline
(40:60). Orally dosed with 10 mg/kg of compound (-)–33 or (-)-6 as a suspension
in 0.5% w/w methyl cellulose and 0.2% v/v tween 80 in water.
4

S. Sun et al.
Bioorganic & Medicinal Chemistry Letters 45 (2021) 128133
Fig. 2. Reversal of ATX-II-induced APD90 by 100 nM (-)-6 in human iPSC-CM. Statistical significance of results were analyzed by T-test using Prism version 7
(GraphPad Software).
authors also thank Charles Rivers Laboratories for profiling the selec-
Table 4
tivity of compound (-)-6 and in particularly Carlos Obejero-Paz for the
Mutagenesis studies of rac-17, rac-23 and GX-4195.
evaluation of (-)-6 in human iPSC-CMs. In addition, the authors thank
Compound
hNaV1.5
hNaV1.5 VSD4 R4A
Dr. Steven S. Wesolowski, as well as Professor Hiroyuki Kagechika and
the reviewers for their suggestions during preparation and revision of
this manuscript.
IC50
(μ
M)
IC50 (μM)
rac-17
1.18
0.70
0.55
1.17
0.57
rac-23
GX-4195
> 10
Appendix A. Supplementary data
Preparation and chiral separation of compound rac-6; 1H NMR
spectra of rac-10 and its cis-isomer; protocols for NaV1.5 in vitro profiling
and efficacy assessment protocol in human iPSC-CMs. Supplementary
data to this article can be found online at https://doi.org/10.1016/j.
bmcl.2021.128133.
rested state (-120 mV) to a partially inactivated state (-95 mV) (Fig. S1 in
supplementary data). This fold change is similar to lidocaine (35-fold), a
pore-binding local anesthetic, but much smaller than a VSD4 binding
sodium channel inhibitor such as GX-674 (2400-fold),25 further sup-
porting our conclusion that these aryl sulfonamides bind to the pore
domain.
In summary, we have described the discovery of a series of novel aryl
sulfonamide NaV1.5 inhibitors. Mutagenesis studies suggest that these
potent NaV1.5 inhibitors bind to the local anesthetic binding site in the
pore domain. The tool compound (-)-6 is a potent NaV1.5 inhibitor with
significant advantages over currently available class I antiarrhythmic
agents including its high selectivity over hERG and other cardiac ion
channels, as well as its low brain penetration. Nonetheless, (-)-6 is
effective in shortening prolonged APDs induced by ATX-II in human
iPSC-CMs. (-)-6 represents a new probe in the research of the pharma-
cological functions on NaV1.5.
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The molybdenum-promoted (1 wt%) nickel (skeletal) catalyzed
reduction of epoxides method provides a valuable synthetic entry to
trans cyclic alcohols. Although the mechanism of the trans stereochem-
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Declaration of Competing Interest
The authors declare that they have no known competing financial
interests or personal relationships that could have appeared to influence
the work reported in this paper.
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Acknowledgements
The authors thank chemists at WuXi AppTec for their assistance in
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