The discovery of potent blockers of the canonical transient receptor channels, TRPC3 and TRPC6, based on an anilino-thiazole pharmacophore

Article abstract of DOI:10.1016/j.bmcl.2013.06.047

Lead optimization of piperidine amide HTS hits, based on an anilino-thiazole core, led to the identification of analogs which displayed low nanomolar blocking activity at the canonical transient receptor channels 3 and 6 (TRPC3 & 6) based on FLIPR (carbac

Full text of DOI:10.1016/j.bmcl.2013.06.047

Bioorganic & Medicinal Chemistry Letters 23 (2013) 4979–4984
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
The discovery of potent blockers of the canonical transient receptor
channels, TRPC3 and TRPC6, based on an anilino-thiazole
pharmacophore
David G. Washburn a, Dennis A. Holt a, Jason Dodson a, Jeff J. McAtee a, Lamont R. Terrell a, Linda Barton a,
Sharada Manns a, Anna Waszkiewicz d, Christina Pritchard d, Dan J. Gillie d, Dwight M. Morrow d,
Elizabeth A. Davenport d, Irina M. Lozinskaya b, Jeffrey Guss d, Jonathan B. Basilla d, Lorena Kallal Negron d,
Michael Klein d, Robert N. Willette b, Rusty E. Fries c, Timothy C. Jensen d, Xiaoping Xu b,
Christine G. Schnackenberg b, Joseph P. Marino Jr. a,
⇑
a Department of Chemistry, Heart Failure Disease Performance Unit, Metabolic Pathways and Cardiovascular Therapeutic Area Unit, GlaxoSmithKline,
709 Swedeland Road, King of Prussia, PA 19406, United States
b Department of Biology, Heart Failure Disease Performance Unit, Metabolic Pathways and Cardiovascular Therapeutic Area Unit, GlaxoSmithKline,
709 Swedeland Road, King of Prussia, PA 19406, United States
c Department of Drug Metabolism and Pharmacokinetics, Heart Failure Disease Performance Unit, Metabolic Pathways and Cardiovascular Therapeutic Area Unit,
GlaxoSmithKline, 709 Swedeland Road, King of Prussia, PA 19406, United States
d Platform Technology and Science, Molecular Discovery Research, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, PA 19426, United States
a r t i c l e i n f o
a b s t r a c t
Article history:
Lead optimization of piperidine amide HTS hits, based on an anilino-thiazole core, led to the identification
of analogs which displayed low nanomolar blocking activity at the canonical transient receptor channels
3 and 6 (TRPC3 & 6) based on FLIPR (carbachol stimulated) and electrophysiology (OAG stimulated)
assays. In addition, the anilino-thiazole amides displayed good selectivity over other TRP channels
(TRPA1, TRPV1, and TRPV4), as well as against cardiac ion channels (CaV1.2, hERG, and NaV1.5). The high
oxidation potential of the aliphatic piperidine and aniline groups, as well as the lability of the thiazole
amide group contributed to the high clearance observed for this class of compounds. Conversion of an
isoquinoline amide to a naphthyridine amide markedly reduced clearance for the bicyclic piperidines,
and improved oral bioavailability for this compound series, however TRPC3 and TRPC6 blocking activity
was reduced substantially. Although the most potent anilino-thiazole amides ultimately lacked oral
exposure in rodents and were not suitable for chronic dosing, analogs such as 14–19, 22, and 23 are
potentially valuable in vitro tool compounds for investigating the role of TRPC3 and TRPC6 in cardiovas-
cular disease.
Received 11 April 2013
Revised 12 June 2013
Accepted 17 June 2013
Available online 26 June 2013
Keywords:
Canonical transient receptor potential
channel
TRPC3
TRPC6
Anilino-thiazole
1-Oleoyl-2-acetyl-glycerol
OAG
Published by Elsevier Ltd.
Calcium and sodium ion flux across the plasma membrane is a
powerful signaling mechanism that mediates a wide range of phys-
iologic functions.1 In general, changes in intracellular calcium are
controlled by two processes, (1) release from stores such as the
endoplasmic and sarcoplasmic reticulum, and (2) through influx
across the plasma membrane. The canonical transient receptor po-
tential channels (TRPC) are believed to play a role in both types of
calcium signaling processes.2 In recent years one prominent mech-
anism of activation identified for TRPC channels has been through
1,4,5-inositol triphosphate (IP3) and diacylglycerol (DAG) through
phospholipase C (PLC) activation. Subsequent to PLC activation,
TRPC channels are activated by a direct interaction with DAG.2
The TRPC3, TRPC6, and TRPC7 subfamily of TRPC channels are cal-
cium/sodium permeable, show very high protein sequence homol-
ogy, and are able to function as store operated channels (SOC) as
well as receptor operated channels (ROC). An added element to
their complexity is that they can form heteromultimeric com-
plexes with each other, as well as with TRPC1, TRPC4, and TRPC5.3
The functional relevance of the multimeric complexes is largely
unknown, and may likely contribute to multiple signaling path-
ways. For example, TRPC3 and TRPC6 have been shown to serve
as receptor operated channels in vascular smooth muscle cells,
and likely contribute to regulation of vascular tone.4 In addition
TRPC3 and TRPC6 channels have also been shown to regulate
Gaq-protein receptor signaling. Upstream of TRPC channels, the
key step in the
Gaq-signaling cascade is the generation of
⇑
Corresponding author.
E-mail address: joseph.p.marino@gsk.com (J.P. Marino).
0960-894X/$ - see front matter Published by Elsevier Ltd.
http://dx.doi.org/10.1016/j.bmcl.2013.06.047

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D. G. Washburn et al. / Bioorg. Med. Chem. Lett. 23 (2013) 4979–4984
calcium (Ca2+) flux in cardiac myocytes, and promote cardiac
hypertrophy through activation of calcineurin and NFAT.5
As a result TRPC3 and TRPC6 are associated with cardiovascular
pathophysiology including cardiac hypertrophy/myopathy, and
hypertension.4,6 Due to the association of both TRPC3 and TRPC6
with cardiac hypertrophy, and the unmet medical need associated
with cardiovascular disease, a small molecule drug discovery pro-
gram was undertaken which focused on identifying blockers of
both TRPC3 and TRPC6.
There have been few reports of small molecule blockers of
TRPC3 or TRPC6 in the literature.7 In general, the tool compounds
identified to date suffer from poor selectivity, weak potency, and/
or questionable tractability as potential starting points for drug
discovery. Therefore a TRPC3 and TRPC6 high-throughput screen-
ing (HTS) effort was carried out to identify small molecule blockers
of these channels as starting points for lead optimization and tar-
get validation. This article will highlight the SAR around blocker
activity and pharmacokinetics for this new class of potent, dual
TRPC3 and TRPC6 blockers. A preliminary selectivity profile will
also be detailed.
Intermediate iii was once again subjected to amine coupling to
provide the target molecules. The synthesis of compound 17 was
accomplished by treating the requisite anilino-thiazole carboxam-
ide substrate with N-chloro-succinimide.9
HTS and primary screening was conducted using a FLIPR assay.
TRPC3 or TRPC6 was overexpressed in HEK cells using BacMam
gene transfer. TRPC3 and TRPC6 channel opening causes an influx
of calcium and sodium cations that results in a change in electrical
potential across the cell membrane. This change in membrane
potential was monitored using membrane potential dyes with
measurements recorded using a FLIPR Tetra instrument. The Gaq
-
coupled receptor agonist carbachol was used as an agonist chal-
lenge, creating the baseline change in membrane potential.2b,c
Inhibitors were evaluated based on their ability to block Gaq
-
receptor driven calcium/sodium ion influx which occurs through
TRPC3 or TRPC6 activation by virtue of the carbachol challenge.
Anilino-thiazoles 2 and 3 were among the most potent hits identi-
fied from a TRPC6 HTS (Fig. 1). HTS hit 2 inhibited carbachol-in-
duced TRPC3 and TRPC6 mediated Ca2+/Na+ flux with an IC50 of
about half-micromolar in the FLIPR assay (Table 1).
Among the TRPC3 or TRPC6 blockers identified to date, one of the
most extensively profiled has been a compound referred to in the lit-
erature as Pyr3 or ethyl-1-(4-(2,3,3-trichloroacrylamide)phenyl)-5-
(trifluoro-methyl)-1H-pyrazole-4-carboxylate (1; Fig. 1).7b Within
the TRPC family, Pyr3 has been shown to be a selective inhibitor of
TRPC3-mediated Ca2+ influx as evidenced by studies in human
embryonic kidney (HEK) cells over-expressing the TRPC family
members (TRPC1, 3, 4, 5, 6, and 7). In addition, Pyr3 inhibits hyper-
trophic signaling in cardiac myocytes and hypertrophic growth in a
pressure overload model in mice.7 However one noteworthy charac-
teristic of the class of 5-(trifluoro-methyl)-1H-pyrazoles to which
Pyr3 belongs is that they are known to be blockers of Ca2+ release-
activated calcium (CRAC) channels such as Orai.8 This cross-activity
and the potentialfor other cross-activities raises questions about the
utility of this class of compounds for TRPC3 and TRPC6 target valida-
tion studies. Our efforts in this area began with the discovery of two
anilino-thiazole hits (2 and 3; Fig. 1) identified from high throughput
screening, with an overall objective of identifying a tool molecule
with good potency, selectivity, and oral PK for study in chronic mod-
els of heart failure.
Target molecules 2–25 were synthesized either through
Method 1 or Method 2 described in Scheme 1. The 4-carboxy-
anilino-thiazole core was readily accessible from two starting
points, bromopyruvate i or ethyl 2-bromo-thiazole-4-carboxylate
ii. Condensation of a phenyl-thiourea iv with the appropriately
substituted bromopyruvate gave rise to the anilino-thiazole iii
shown in Scheme 1 (Method 1). Amide formation with the requi-
site amine delivered the target molecules. Substitution of bromo-
thiazole ii with the appropriate aniline, followed by hydrolysis,
gave rise to intermediate iii (Method 2).
The dual activity observed at both channels was not surprising
given the high sequence homology between TRPC3 and TRPC6. Ini-
tial lead optimization efforts around 2 focused on the aniline ring
since substitution was more readily probed due to the wide variety
of commercially available anilines. A combination of electron
donating and withdrawing groups were introduced on the aniline
to determine their effect on activity. Replacement of the 4-
methyl-phenyl group in example 2 with 4-chloro-phenyl (4) or
4-methoxy-phenyl (5) did not result in a significant activity
change. Installation of a 2-chloro-substituent (6) led to a substan-
tial drop in activity (8- to 10-fold) at both TRPC3 and TRPC6
relative to HTS hit 2. The combination of two deactivating groups,
2-fluoro-4-chloro (7), also resulted in almost no change in TRPC3
or TRPC6 activity. In addition, meta-substitution of the aniline ring
did not change activity as compared to para-substitution (3-Cl-
phenyl and 3-methoxy-phenyl were synthesized—data not
shown). The combination of donorgroups at the 3- and 4-positions
(3,4-methylenedioxy; 8) did not have a significant effect on activity
either. Contrary to the flat SAR observed around the aniline, SAR
around the piperidine group proved to be fairly sensitive, with
mainly small alkyl groups tolerated at the 2- and 4-positions
(2 and 9); introduction of larger groups such as phenyl (10–12)
and cyclohexyl (13) resulted in little or no activity irrespective of
the point of attachement to the piperidine. The addition of two
methyl groups, in the form of a 2,3-dimethyl-piperidine moiety
(14), proved to be the most potent substitution pattern, resulting
in a slight increase in TRPC3 activity, and a five fold improvement
in TRPC6 activity relative to screening hit 2. The combination of
2,3-dimethyl-piperidine and 3,4-methylenedioxy-aniline (15) of-
fered an even greater improvement in potency, as TRPC3 and
O
EtO
N
F3C
N
O
O
Me
OMe
Me
N
N
N
N
Cl
N
H
N
H
S
S
HN
Cl
2
3
1
O
Cl
Figure 1. Pyr3 and anilino-thiazole HTS hits.

D. G. Washburn et al. / Bioorg. Med. Chem. Lett. 23 (2013) 4979–4984
4981
O
Br
HO
Method 1
S
O
R2
i.
i
H2N
N
H
R1
R1
iv
EtOH, reflux R2 = H, Me
ii.
NH2
O
O
HO
EtO
Method 2
EtOH, µv
iii. NaOH
N
N
R2
R1
N
Br
S
S
H
ii
iii
R3
R3
O
O
HO
R2
N
R2
NH
iv.
N
N
R1
R1
N
H
N
BOP, DIEA
or
EDC, HOBT
S
iii
S
H
2-25
Scheme 1. Synthesis of 2-anilino-thiazole amides. Reagents and conditions: (i) iv, EtOH, reflux (60–100%). (ii) aniline, EtOH,
(iv) amine, BOP, DIEA, DMF, rt or amine, EDC, HOBT, CH2Cl2, rt (60–80%).
lv (20–50%). (iii) NaOH, EtOH, reflux (90–100%).
Table 1
FLIPR SAR of anilino-thiazole piperidine amides
O
R3
N
R2
N
R1
N
H
S
R1
R2
R3
hTRPC3 IC50 (nM)
hTRPC6 IC50 (nM)
a
a
Ex
2
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
4-Me
4-Cl
4-OMe
2-Cl
2-F,4-Cl
3,4-(O-CH2-O)
4-Me
4-Me
4-Me
4-OMe
4-Me
4-Me
3,4-(O-CH2-O)
2-F-4,5-(O-CH2-O)
2-F-4,5-(O-CH2-O)
2-F,4-Cl
2-F,4-Cl
2-F,4-Cl
H
H
H
H
H
H
H
H
H
H
H
H
4-Me
4-Me
4-Me
4-Me
4-Me
4-Me
2-Me
2-Ph
3-Ph
4-Ph
4-Cyclohexyl
2,3-Me
2,3-Me
2,3-Me
2,3-Me
630
800
800
6300
1600
400
400
800
800
3160
630
160
630
15800
>25,000
1600
4000
80
16
25
4
50
16
1600
800
12600
>25,000
2500
6300
250
80
160
32
250
H
Me
Cl
Me
Me
Me
2,3-Me
(S,S)-2,3-Me
(R,R)-2,3-Me
100
1000
a
Values are means ( 2- to 3-fold) from at least three independent experiments; h = human.
TRPC6 potency increased 8- and 20-fold respectively compared to
hit 2. In an effort to deactivate the aromatic system towards oxida-
tion and block potential sites of metabolism on the thiazole, a
2-fluoro-group was inserted at the aniline ortho-position and a
methyl-group was incorporated at the 5-position of the thiazole
15. Analog 16 did not have a significant effect on potency and
unfortunately little effect on pharmacokinetics (vide infra).
Replacement of the methyl-group with a chlorine atom (17) at
the thiazole 5-position led to a dramatic improvement in potency
relative to hit 2, especially in terms of TRPC6, as potency improved
100-fold. Replacement of the 2-fluoro-4,5-methylenedioxy-aniline
in 16 with 2-fluoro-4-chloro-aniline (18), an aniline group that was
believed to offer reduced iv clearance relative to the methylenedi-
oxy-aniline, did not have a significant effect on potency. The (S,S)-
2,3-dimethyl-piperidine enantiomer (19) offered comparable
TRPC3/6 potency to the racemate (18), while the (R,R)-2,3-di-
methyl-piperidine enantiomer (20) resulted in a four fold loss of
TRPC3 activity and almost a 30-fold loss of TRPC6 activity.
Although the robust blocking activity observed in the FLIPR assay
provided evidence that anilino-thiazole leads were blocking TRPC3-
or TRPC6-mediated Ca2+/Na+ flux in cells, more direct evidence was
sought to further validate the mechanism of action. Since carbachol-
mediated Gaq activation is upstream of TRPC3/6, a more down-
stream activator was targeted. It has been well established that
the endogenous activator of TRPC3 and TRPC6, diacylglycerol
(DAG), does not have suitable stability for electrophysiology studies.
Therefore a surrogate glycerol, 1-oleoyl-2-acetyl-glycerol (OAG),
was used to activate TRPC3 or TRPC6 in cultured cells.2 As shown

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D. G. Washburn et al. / Bioorg. Med. Chem. Lett. 23 (2013) 4979–4984
in Figure 2, OAG (10
l
M) produced a significant increase in both in-
proved to be more selective than the 4-methyl-aniline 14. Analog
19 was over 1500-fold selective over TRPA1, 390-fold selective
over TPRV1, and 780-fold selective over TRPV4. Selectivity against
non-TRP ion channels which impact cardiovascular safety was also
examined.11 Amide examples 14 and 19 were screened against the
cardiac calcium (CaV1.2), sodium (NaV1.5), and potassium (hERG)
channels. While both compounds displayed excellent cardiac ion
channel selectivity in general, the 2-fluoro-4-chloro-aniline 19 dis-
played only modest (100-fold) selectivity over the sodium channel.
In addition to our efforts to improve potency and oral PK in the
piperidine amide series, we also attempted to address those same
parameters in the tetrahydroisoquinoline amide series (3). The 4-
methoxy-aniline (3) in the isoquinoline amide series displayed
ward and outward TRPC3 and TRPC6 currents in HEK cells heterolo-
gously expressing TRPC3 or TRPC6.2
The resulting TRPC3 or TRPC6 current was inhibited by the po-
tent blocker example 14 providing direct evidence that the anilino-
thiazoles were blocking OAG-stimulated TRPC3 or TRPC6 current.
In general, most piperidine amides displayed modest to high
clearance, a short mean residence time (MRT), and poor oral bio-
availability as described in Table 2. The most promising analog in
terms of bioavailability (64%) was 19, however clearance and
MRT were inadequate to produce drug levels to support chronic
dosing. The high in vivo clearance observed for this series was
bourne out in microsomal intrinsic clearance studies, as nearly
all piperidine amides screened displayed high clearance
(>100 ml/min/kg). It is likely that both gut instability of the amide
functionality and cytochrome P450 oxidation of aliphatic/aromatic
groups contributed to the moderate to high clearance observed for
the piperidine amide subclass of anilino-thiazoles.
Table 3
Selectivity against TRP families and cardiac ion channels
Ex
TRPA1
TRPV1
TRPV4
CaV1.2
hERG
NaV1.5
Anilino-thiazole selectivity against other notable TRP families
was also explored (Table 3).10 Analog 14 was found to be 100-fold
selective over TRPA1, 15-fold selective over TRPV1, and about 80-
fold selective against TRPV4. The 2-fluoro-4-chloro-aniline 19
14
19
8000
25,000
1260
6300
6300
12,500
10,000
10,000
>50,000
>50,000
50,000
3300
Values are a means( 2- to 3-fold) of at least two experiments. IC50s (nM) shown.
Figure 2. Activation and blockade of TRPC3 and TRPC6 channels heterologously expressed in HEK cells. Top left: time course of inhibition of OAG (10
current by example 14 (0.01 and 0.03
M); current amplitudes were measured at À80 mV and +80 mV. Top right: current/voltage relationship of OAG-activated hTRPC3
current in the presence and absence of example 14. Bottom left: time course of inhibition of OAG (10 M) activated hTRPC6 current by example 14 (0.01 and 0.03 M);
lM) activated hTRPC3
l
l
l
current amplitudes were measured at À80 mV and +80 mV. Bottom right: current/voltage relationship of OAG-activated hTRPC6 current in the presence and absence of
example 14.
Table 2
Piperidine amide pharmacokinetic parameters in the rat
Ex
Dose (iv) (mg/kg)
Cmax (iv) (ng/ml)
CL (iv) (ml/min/kg)
MRT (iv) (h)
DNAUC (iv) (hÁkgÁL)
%F
14
15
17
19
1.04
1.05
0.86
0.82
310
340
490
120
75
86
46
2.8
2.1
0.4
0.7
0.2
0.2
0.3
0.1
<1
<1
7
150
64
Values are means 10%, from 2 to 3 animals; Cmax—maximum concentration; CL—clearance; DNAUC—dose normalized area under the curve;%F—percent oral bioavailability.

D. G. Washburn et al. / Bioorg. Med. Chem. Lett. 23 (2013) 4979–4984
4983
Table 4
FLIPR SAR of anilino-thiazole isoquinoline analogs
R3
O
X
N
N
R2
R1
N
H
S
a
a
Compd
R1
R2
R3
X
hTRPC3 IC50 (nM)
hTRPC6 IC50 (nM)
3
4-OMe
H
H
H
Me
Me
Me
H
H
Me
Me
Me
H
CH
CH
CH
CH
N
1260
500
316
316
10,000
20,000
500
160
63
32
1260
6300
21
22
23
24
25
3,4-(O-CH2-O)
3,4-(O-CH2-O)
3,4-(O-CH2-O)
3,4-(O-CH2-O)
2-F,4-Cl
N
a
Values are means ( 2- to 3-fold) from at least three independent experiments.
Table 5
Isoquinoline amide pharmacokinetic parameters in the rat
Compd
Dose (iv) (mg/kg)
Cmax (iv) (ng/ml)
CL (iv) (ml/min/kg)
MRT (iv) (h)
DNAUC (iv) (hÁkg/L)
%F
3
24
25
0.93
1.06
0.92
250
1800
510
120
9.3
22
0.3
1.3
1.6
0.14
1.86
0.85
ꢀ1
65
100
Vdss ranged from 0.7 to 2 L/kg.
Values are means 10%, from 2 to 3 animals.
comparable TRPC3/6 activity to the corresponding 4-methoxy-ani-
line (5) in the piperidine amide series. In general, substitution of
the ‘benzo’ portion of the tetrahydroisoquinoline was unremark-
able. Groups such as cyano, chloro, fluoro, or methyl (irrespective
of their position on the ‘benzo’ ring) did not change activity relative
to 3. The 3,4-methylenedioxy-aniline (21) group did not signifi-
cantly alter TRPC3/6 potency compared to 4-methoxy-aniline (3)
(Table 4). Introduction of a methyl group at the 2-position (R3)
of the isoquinoline ring (22) led to an eight fold improvement in
TRPC6 potency relative to hit 3. This could be due in part to the
R3 methyl’s ability to bias a particular amide conformer. Interest-
ingly, TRPC6 potency was further enhanced with analog 23 when
methyl substitution at both the isoquinoline 2-position and the
thiazole 5-position was introduced. These changes delivered a
15-fold improvement over (3).
In an attempt to decrease the lipophilicity of the isoquinoline
system, carbon-5 of the isoquinoline was replaced with a nitrogen
creating a 5,6,7,8-tetrahydro-1,6-naphthyridine ring system. The
5,6,7,8-tetrahydro-1,6-naphthyridine was selected to test this
hypothesis due to ease of synthesis. A significant decrease in activ-
ity was observed for 5,6,7,8-tetrahydro-1,6-naphthyridine 24 as
compared to isoquinoline 23, suggesting that the benzo-portion
of the molecule resides in a highly lipophilic region of the TRPC3
and TRPC6 ion channels. Similarly, the 2-fluoro-4-chloro-aniline
analog 25 also displayed markedly reduced TRPC3 and TRPC6
blocking activity. Although the naphthyridine analogs displayed
reduced TRPC3/6 potency, oral pharmacokinetic (PK) properties
were markedly improved over initial lead 3. Especially in the case
of analog 24, where all PK parameters were enhanced by about one
order of magnitude (Table 5). Despite numerous attempts to
introduce substitution in combination with the 5,6,7,8-tetrahy-
dro-1,6-naphthyridine, no additional analogs were identified
which possessed submicromolar potency and acceptable oral
pharmacokinetics.
FLIPR (carbachol stimulated) and electrophysiology (OAG
stimulated) assays. In addition, anilino-thiazole amides 14 and
19 displayed good selectivity over other TRP channels (TRPA1,
TRPV1, and TRPV4), as well as over cardiac ion channels (CaV1.2,
hERG, and NaV1.5). The significant oxidation potential of the ali-
phatic piperidine and aniline groups, as well as the lability of the
thiazole amide group likely contributed to the high clearance ob-
served for the anilino-thiazole class of compounds. While the con-
version of the isoquinoline amide to a naphthyridine amide
reduced clearance and improved oral bioavailability, TRPC3 and
TRPC6 blocking activity was reduced substantially. Although the
more potent anilino-thiazole amides lacked oral exposure in ro-
dents suitable for chronic dosing, analogs such as 14–19, 22, and
23 are potentially valuable in vitro tool compounds useful for
investigating the role of TRPC3 and TRPC6 in disease models. Eval-
uation of this class of TRPC3/6 tool compounds in cardiac myocytes
will be the subject of a forthcoming article.12
Acknowledgments
The authors would like to thank Jon Jaworski and Robert Midg-
ett for screening and profiling. In addition the authors would like to
thank James Fornwald for his efforts in preparing the TRPC3 and
TRPC6 BacMam reagents.
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.bmcl.2013.06.
047.
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tification of analogs which displayed low nanomolar potency in

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