Identification of diamino chromone-2-carboxamides as MCHr1 antagonists with minimal hERG channel activity

Article abstract of DOI:10.1016/j.bmcl.2006.11.068

A series of potent 2-carboxychromone-based melanin-concentrating hormone receptor 1 (MCHr1) antagonists were synthesized and evaluated for hERG (human Ether-a-go-go Related Gene) channel affinity and functional blockade. Basic dialkylamine-terminated anal

Full text of DOI:10.1016/j.bmcl.2006.11.068

Bioorganic & Medicinal Chemistry Letters 17 (2007) 2365–2371
Identification of diamino chromone-2-carboxamides as
MCHr1 antagonists with minimal hERG channel activity
Andrew S. Judd,a,* Andrew J. Souers,a Dariusz Wodka,a Gang Zhao,a
Mathew M. Mulhern,a Rajesh R. Iyengar,a Ju Gao,a John K. Lynch,a
Jennifer C. Freeman,a H. Douglas Falls,a Sevan Brodjian,a Brian D. Dayton,a
Regina M. Reilly,a Gary Gintant,b James T. Limberis,b Ann Mikhail,b Sandra T. Leitza,b
Kathryn A. Houseman,b Gilbert Diaz,b Eugene N. Bush,a Robin Shapiro,a
Victoria Knourek-Segel,a Lisa E. Hernandez,c Kennan C. Marsh,c
Hing L. Sham,a Christine A. Collinsa and Philip R. Kyma
aMetabolic Disease Research, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, IL 60064, USA
bIntegrative Pharmacology, Metabolic Disease Research, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, IL 60064, USA
cExploratory Pharmacokinetics, Metabolic Disease Research, Abbott Laboratories, 100 Abbott Park Road,
Abbott Park, IL 60064, USA
Received 25 October 2006; revised 14 November 2006; accepted 20 November 2006
Available online 1 December 2006
Abstract—A series of potent 2-carboxychromone-based melanin-concentrating hormone receptor 1 (MCHr1) antagonists were syn-
thesized and evaluated for hERG (human Ether-a-go-go Related Gene) channel affinity and functional blockade. Basic dialkyl-
amine-terminated analogs were found to weakly bind the hERG channel and provided marked improvement in a functional
patch-clamp assay versus previously reported antagonists of the series.
Ó 2006 Elsevier Ltd. All rights reserved.
Melanin-concentrating hormone (MCH) is a cyclic
19-amino acid neuropeptide that serves as an important
mediator of food intake and energy balance in mam-
mals.1,2 Various data suggest that interruption of
MCH signaling could be an effective anti-obesity thera-
py. For example, transgenic mice overexpressing the
MCH gene are insulin resistant and obese,3 while mice
lacking the gene encoding MCH are hypophagic, lean,
and maintain elevated metabolic rates.4 Additionally,
mice lacking the gene for encoding the MCH receptor
maintain elevated metabolic rates and remain lean de-
spite hyperphagia on a normal diet.5,6 Indeed, several re-
ports of orally efficacious small-molecule inhibitors of
rodent MCHr1 have recently been published.7,8
In humans, IKr, an inwardly rectifying potassium chan-
nel encoded by the human Ether-a-go-go Related Gene
(hERG), plays an important role in ventricle repolariza-
tion.9 Congenital mutations to the hERG channel (IKr
)
F
O
O
O
N
O
N
F
O
O
F
O
O
N
N
O
H
H
1
2
MCHr1 binding IC50 (nM)a = 3
MCHr1 Ca2+ fluxIC50 (nM)b = 29
1
MCHr1 binding IC50 (nM)a= 24
6
7
MCHr1 Ca2+ fluxIC50 (nM)b= 168 12
hERG (dof) IC50 (μM)c = 15.1 4.6
hERG (dof) IC50 (μM)c= 8.3 0.92
Chart 1. Chromone-based MCHr1 antagonists. aDisplacement of
125I]-MCH from MCHr1 expressed in IMR-32 (I3.4.2) cells (MCH
In the electrocardiogram, the QT interval represents the
time during which ventricles depolarize and repolarize.
[
binding Kd = 0.66 0.25 nM, Bmax = 0.40 0.08 picomol/mg).11
bInhibition of MCH-mediated Ca2+ release in whole IMR-32 cells
(MCH EC50 = 62.0 3.6 nM). cDisplacement of [3H]-dofetilide from
1
2
hERG/HEK membrane homogenates at 6 concentrations, log apart,
in duplicate, using a 96-well plate design. IC50 values calculated using
Graphpad Prizm software.
Keywords: MCHr1; Obesity; hERG; Patch-clamp.
*
Corresponding author. Tel.: +1 847 935 3375; fax: +1 847 938
1674; e-mail: andrew.judd@abbott.com
0960-894X/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2006.11.068

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A. S. Judd et al. / Bioorg. Med. Chem. Lett. 17 (2007) 2365–2371
are responsible for QT prolongation, resulting in poten-
tially life-threatening cardiac arrhythmias such as tor-
sades de pointes. Moreover, small molecule blockade of
the hERG channel has been associated with acquired
QT prolongation, which in some instances has led to
similar untoward effects and, ultimately, to the removal
of the offending agents from the consumer market. Ac-
quired QT prolongation is now considered a significant
risk factor for human safety predictions of drug candi-
dates, making hERG channel cross-reactivity a poten-
tially severe liability.
However, initial efforts to directly couple 3 with a vari-
ety of substituted alcohols under the action of DBAD
and PS–Ph3P in THF were beset by incomplete reaction.
While this method variably delivered sufficient quanti-
ties of materials 4 for initial in vitro testing, we found
the sequence of Mitsunobu reaction of the more acidic
hydroxybenzaldehyde 5 (vs 3) with the appropriate alco-
hol to generate 4-alkoxybenzaldehydes 6 and subse-
quent reductive amination with the piperidine 7 to be
more efficient and amenable to preparations of 4 on
scale (see Scheme 1).
A previous report10 from these laboratories described
the optimization of chromone-based MCHr1 antagonist
1 (Chart 1) and detailed its in vivo weight-loss efficacy in
a DIO mouse model of obesity. However, the high ther-
apeutic plasma Cmax (7.7 lM) required to induce effica-
cy eroded the observed in vitro selectivity windows and
rendered the attainment of a satisfactory safety window
impossible. Specifically, 1 showed 90% functional block-
ade of the hERG tail current in a patch-clamp assay at
the efficacious plasma Cmax. The detrimental effect of the
blockade was confirmed in the pentobarbital-anesthe-
tized dog model, where significant QT prolongation at
low multiples of the therapeutic plasma Cmax was
observed.
Cognizant of our aforementioned forays into hERG-se-
lective MCHr1 antagonists in which drug distribution
was effectively limited or even excluded from the brain,12
we initially focused on introducing polarity to the ben-
zylamine unit by moieties that would likely maintain
high volumes of distribution, such as tethered dialkyl
amines. Thus, incorporation of cyclic amines by an ethyl
linker was unproductive, as the diamines 4a and 4b
weakly bound to MCHr1 and had no functional potency
in the Ca2+ flux assay (see Table 1). Attachment of a
dialkyl amine by an n-propyl tether in compounds such
as 4c and 4d, however, had more beneficial results, res-
cuing both the MCHr1 binding and functional poten-
cies. Indeed, 4d was approximately twice as
functionally potent as the methyl ether 2. Encouraged
by these results, we assayed the compounds in a hERG
channel affinity screen (displacement of [3H]-dofetilide,
see Table 1). We were intrigued to find that 4c and 4d
had considerably less hERG channel affinity than the
parents 1 and 2, with the smaller, less lipophilic R1
group in 4c seemingly more beneficial in this regard.
In contrast, related terminal ethers such as 8 had in-
creased affinity for the hERG channel relative to 1 and
2, with only modest affinity for MCHr1. In accord with
this trend, the lipophilic trifluoroethyl ether 9 was the
most potent binder of the hERG channel within this
preliminary subset.
Henceforth, advancement of the chromone series would
likely necessitate a decrease in the therapeutic plasma
Cmax and that greater off-target selectivity be engineered
into the series, particularly with respect to the hERG
channel. In this letter, we disclose the MCHr1- and
hERG-related SARs of a chromone-based sub-series.
Compounds with excellent MCHr1 binding affinity,
good MCHr1 functional activity, weak hERG channel
binding affinity, and greatly diminished hERG channel
functional blockade relative to 1 are highlighted. Ade-
quate CNS penetration of optimized analogs upon oral
dosing prompted their evaluation in a 2-week study in
DIO mice.
Previous work10 detailed the study of the piperidine
linker and 2-carboxychromone sub-unit of 1, wherein
the 7-fluoro-substituted permutation was considered
optimized with respect to MCHr1 potency, CNS pene-
tration, and hERG selectivity. Our studies have also re-
vealed that incorporation of polar substituents into the
benzylamine moiety greatly diminishes the hERG affin-
ity of the resultant analogs, though at the cost of requi-
site CNS exposure.10,12 As we considered various
alternative ‘leads’ to the development of hERG-selec-
tive13 MCHr1 antagonists that could efficiently pene-
trate the brain, our attention was drawn to the
previously reported10 2, which carries a 3-fluoro-4-meth-
oxy aryl substituent in place of the piperonyl moiety
found in parent 1. Considering its good functional
potency (MCHr1 Ca2+ flux IC50 = 168 nM) and the po-
tential for rapid modification of the benzyl unit via its
ether bond, we selected 2 as the root of a more general
analog library.
7-F-Ch
F
F
O
N
O
N
R
F
O
O
a
7-F-Ch
N
O
N
H
OH
H
3
4
Incomplete Conversion
O
O
a
b
F
F
R
O
NH
OH
O
7-F-Ch
N
H
5
6
7
F
O
N
F
O
O
R
N
O
H
4a-d
Scheme 1. Reagents and conditions: (a) ROH, DBAD, PS–Ph3P,
THF, 50 °C (60–80% for 5 to 6); (b) NaBH(OAc)3, AcOH, THF, rt
(60–70%).
We chose to survey the SAR of ether 2 by means of
Mitsunobu reaction-based elaboration of the phenol 3.

A. S. Judd et al. / Bioorg. Med. Chem. Lett. 17 (2007) 2365–2371
Table 1. Binding affinity and functional potency of MCHr1 antagonistsa
2367
R2
O
N
F
O
O
R1
N
O
H
Compound
R1
R2
MCHr1 binding
IC50 (lM)b,e
MCHr1 Ca2+ flux
IC50 (lM)c,e
hERG (dof)
IC50 (lM)d,e
2
CH3
F
F
0.024
0.168
NTf
8.3
O
4a
>2
NTf
NTf
65
N
4b
4c
4d
8
F
F
F
H
F
F
F
F
F
F
1.52
>10
N
N
0.020
0.003
0.165
0.064
NTf
0.773
0.086
1.75
N
42
4.3
1.6
34
O
9
CF3CH2-
NTf
N
4f
4g
4h
4i
4j
NTf
O
N
0.051
0.031
0.015
0.004
4.01
0.74
3.2
0.45
8.5
N
N
0.480
1.98
O
O
O
N
0.545
S
O
a All compounds were >95% pure by HPLC and characterized by 1H NMR and HRMS.
b See Chart 1, footnote a.
c See Chart 1, footnote b.
d See Chart 1, footnote c.
e Values represent an average of at least two determinations.
f NT, not tested.
To further investigate the requirements for favorable
hERG selectivity, we synthesized close structural ana-
logs of 4c and 4d having attenuated basicity at the termi-
acetal to provide the differentiated bis-aldehyde equiva-
lent 9 (Scheme 2). Reductive amination with 7 under
standard conditions and subsequent treatment of the ad-
duct with aqueous HCl revealed the aldehyde 10. Con-
densation of 10 with O-alkylhydroxylamines gave 4h
and 4i. The thiazolidinedione 4j was made from phenol
5 by the 3-step sequence of alkylation with 3-bromopro-
panol, Mitsunobu reaction with thiazolidinedione, and
reductive amination.
nal
amine.
Thus,
the
morpholino
and
dicyclopropylamino14 analogs 4f and 4g were synthe-
sized according to the methods outlined in Scheme 1
for similar substrates. We were also interested in the ef-
fect of polar non-ionizable termini on the hERG affinity
of the sub-series and, therefore, assayed the oxime ethers
4h, 4i and the thiazolidinedione 4j, which were made
according to Scheme 2.
Evaluation of morpholine 4f and dicyclopropylamine 4g
(see Table 1) revealed their increased hERG affinity rel-
ative to the piperidine 4d. Notably, inclusion of the
weakly basic dicyclopropylamino moiety resulted in a
The syntheses of 4h and 4i commenced with alkylation
of benzaldehyde 5 with bromo-acetaldehyde dimethyl

2368
A. S. Judd et al. / Bioorg. Med. Chem. Lett. 17 (2007) 2365–2371
Scheme 3. Reagents and conditions: (a) R2NCH2CH2NH2, EDCI,
HOBt, NMM, DMF (65–95%); (b) Ra–Ni, NaH2PO2, pyridine,
AcOH, H2O (60–70%); (c) 7, NaBH(OAc)3, AcOH, THF, rt (67%);
(d) NBS, AIBN, CCl4, 90 °C (30–65%); (e) 7, K2CO3, EtOH (40–75%).
Scheme 2. Reagents and conditions: (a) (MeO)2CHCH2Br, K2CO3,
acetone; 50 °C (78%); (b) 7, MP–CNBH3, AcOH, MeOH, 50 °C
(50–80%); (c) acetone, 1N HCl, 70 °C (95%); (d) RONH3Cl, MeOH, rt
(80–90%); (e) 3-bromopropanol, K2CO3, DMF; 80 °C (77%); (f)
thiazolidinedione, DBAD, PS–Ph3P, THF, 50 °C (65%).
of the corresponding aniline with commercially avail-
able 3-piperidine-1-yl propionyl chloride.
To our delight, replacement of the ether tether with a
benzamide-type linkage to give 16a (Chart 2) provided
an additional decrease in the hERG channel affinity,
as no inhibition of dofetilide binding was seen up to
the measured assay concentration. This compound re-
tained excellent MCHr1 binding affinity, but the amido
unit was detrimental to the MCHr1 functional potency,
resulting in nearly a fourfold decrease with respect to
ether 4d. Conversely, the ‘reversed amide’ 20 retained
much of the MCHr1 binding and functional potency
of 4d. Interestingly, however, 20 had hERG affinity
comparable to the methyl ether 2, ostensibly due, in
part, to attenuation of the terminal amine’s pKa by the
beta-disposed carbonyl group.
compound (4g) with sub-micromolar affinity for the
hERG channel and with greatly diminished MCHr1
functional potency. Interestingly, the hERG channel
affinities of 4d, 4f, and 4g correlate with the pKa of the
terminal amine’s conjugate acid, supporting the notion
that increased cationic character at the terminus inhibits
hERG channel binding. Compounds with non-ionizable
polar oxime ether termini, such as 4h, were relatively
good binders to the hERG channel. The 10-fold increase
in hERG channel affinity acquired in the iso-butyl for
methyl exchange on going from 4h to 4i was also partic-
ularly striking. Finally, the polar thiazolidinedione 4j
was an exceptional binder to MCHr1, but had very
modest MCHr1 functional potency and offered no ben-
efit in terms of hERG selectivity over the parent methyl
ether 2.
Guided by these results, we surveyed the MCHr1 and
hERG channel SARs of benzamides related to 16a.
The archetype 16b, lacking the 2-fluoro substitution,
had MCHr1 activity similar to 16a, but had slightly
higher binding affinity for the hERG channel. As with
the ether-linked analogs, changes to the basicity and/or
lipophilicity of the terminal component directly affected
the MCHr1 functional potency and hERG selectivity.
For example, the 4,4-difluoropiperidine-substituted ana-
log 16c was 5-fold less functionally potent at MCHr1
than 16b, and its binding affinity for the hERG channel
increased by 10-fold. Substitution to the phenyl ring also
Having found that basic 3-propylamino moieties in
antagonists such as 4d retained good MCHr1 potency
and deterred hERG channel binding, we next explored
modification to the 4-atom tether connecting the phenyl
ring to the amine terminus. We hypothesized that a
more polar15 linker would further decrease hERG chan-
nel binding and, hence, elected to probe the effect of
amide-based tethers on the hERG and MCHr1 affinities
of the sub-series.
Representative amides 16 were made according to
Scheme 3. The 2-fluoro analog (Table 2 numbering)
16a was conveniently made from commercially available
2-fluoro-4-cyanobenzoic acid 13. Thus, EDCI-mediated
amide coupling gave 14, which was partially reduced to
the aldehyde 15 with Raney Nickel. Reductive amina-
tion with 7 as described previously gave the analog
16a. Alternatively, 3-chloro-4-methyl- or 3-methoxy-4-
methyl benzoic acids were functionalized under radical
conditions to give the benzyl bromides 18 (Scheme 3).
Alkylation with 7 followed by standard amide forma-
tion with 2-aminoethylpyrrolidine yielded the analogs
16d, 16e. The ‘reversed-amide’ 20 was made by acylation
F
F
O
N
O
N
O
N
F
O
O
O
F
O
O
N
N
N
H
H
H
HN
N
16a
20
MCHr1 binding IC50 (μM)a,d = 0.029
MCHr1 Ca2+ flux IC50 (μM)b,d = 0.420
hERG (dof) IC50 (μM)c,d = > 100
MCHr1 binding IC50 (μM)a,d = 0.023
MCHr1 Ca2+ flux IC50 (μM)b,d = 0.120
hERG (dof) IC50 (μM)c,d = 9.18
Chart 2. Amide-based MCHr1 antagonists. aSee Chart 1, footnote a.
bSee Chart 1, footnote b. cSee Chart 1, footnote c. dSee Table 1,
footnote e.

A. S. Judd et al. / Bioorg. Med. Chem. Lett. 17 (2007) 2365–2371
Table 2. Binding affinity and functional potency of MCHr1 antagonistsa
2369
R3
R2
O
N
H
F
O
O
N
R1
3
N
2
H
O
Compound
16a
R1
R2
2-F
H
R3
H
H
H
H
H
MCHr1 binding
IC50 (lM)b, e
MCHr1 Ca2+
hERG (dof)
IC50 (lM)d,e
flux IC50 (lM)c,e
N
0.029
0.017
0.086
0.002
0.026
0.009
0.420
0.519
2.93
>100
N
N
16b
66
F
16c
H
6.3
11
F
N
N
N
16d
3-Cl
0.136
0.270
1.9
16e
3-OCH3
3-CH2
6.6
23
16f
CH2
a All compounds were >95% pure by HPLC and characterized by 1H NMR and HRMS.
b See Table 1, footnote b.
c See Table 1, footnote c.
d See Table 1, footnote d.
e See Table 1, footnote e.
greatly affected the affinities for the MCH receptor and
hERG channel, as already noted for the 2-fluoro deriv-
ative 16a. Substitution at the 3-position with a chlorine
atom or methoxy group provided functionally potent
MCHr1 antagonists 16d and 16e, but negated the previ-
ously observed beneficial effect of the terminal basic
amine on hERG affinity. The racemic, constrained inda-
nyl 16f also lost functional MCHr1 potency and had
hERG affinity comparable to the piperonyl 1.
of functional hERG current blockade, as summarized
in Table 3. Compound 1, which was previously shown
to induce QT prolongation in the anesthetized-dog mod-
el at therapeutically relevant plasma concentrations, was
chosen as a standard compound and found to cause
100% inhibition of the hERG tail current at 30 lM drug
concentration.16 The ether 4d induced 57% inhibition at
the same concentration, an improvement that roughly
correlated with its relative increase in hERG binding
IC50. Despite the apparent difference in the hERG bind-
ing IC50’s of the amides 16a and 16b, the functional
assay at 30 lM drug concentration revealed they were
nearly equally benign to the hERG tail current, impart-
ing 21% and 13% inhibition, respectively, and thus
represented marked improvements to hERG channel
cross-reactivity as measured by this parameter.
Several analogs with varying affinities for the hERG
channel were chosen for study in a patch-clamp assay
Table 3. Selected parameters for compounds 1, 4d, 16a, and 16b
Compound
MCHr1
binding
hERG
(dofetilide)
IC50 (lM)
Patch-clamp: tail
current inhibition
at 30 lMa
IC50 (lM)
The fluorinated amide 16a was chosen for pharmacoki-
netic (PK) analysis to assess the CNS-penetrating ability
of this hERG-selective class of MCHr1 antagonists.
Acute oral dosing (10 mpk) of 16a in DIO mice exposed
an interesting PK profile (see Table 4) characterized by a
shallow plasma Cmax (598 ng/mL) and a relatively short
(2 h) plasma t1/2. Additionally, 16a showed a long (8 h)
half-life in the brain, leading to 12 h drug concentrations
in the brain (75 ng/g) superior to those in the plasma
(38 ng/mL). We surmised that chronic dosing of an
MCHr1-potent compound with this in vivo profile
1
4d
0.003
0.003
0.013
0.029
15.1
42.0
66.2
>100
100%
57%
13%
21%
16b
16a
a The hERG current was evaluated using HEK 293 cells stably
expressing hERG. Drug effects were evaluated based on changes of
tail currents measured during 4 s repolarizing test pulses to ꢀ50 mV
preceded by a 3 s depolarizing conditioning pulse to 0 mV (holding
potential of ꢀ80 mV, pulses applied once every 15 s). Experiments
were conducted at 36.5–37 °C with a 5 mM external K + HEPES-
buffered Tyrode’s solution.

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A. S. Judd et al. / Bioorg. Med. Chem. Lett. 17 (2007) 2365–2371
Table 4. Selected PK parameters of 16a in DIO mice (10 mg/kg po)a
5. Chen, Y.; Hu, C.; Hsu, C.-K.; Zhang, Q.; Bi, C.; Asnicar,
M.; Hsiung, H. M.; Fox, N.; Slieker, L. J.; Yang, D. D.;
Heiman, M. L.; Shi, Y. Endocrinology 2002, 143, 2469.
6. Marsh, D. J.; Weingarth, D. T.; Novi, D. E.; Chen, H. Y.;
Trumbauer, M. E.; Chen, A. S.; Guan, X-M.; Jiang, M.
M.; Feng, Y.; Camacho, R. E.; Shen, Z.; Frazier, E. G.;
Yu, H.; Metzger, J. M.; Kuca, S. J.; Shearman, L. P.;
Gopal-Truter, S.; MacNeil, D. J.; Strack, A. M.; MacIn-
tyre, D. E.; Van der Ploeg, L. H. T.; Qian, S. Proc. Natl.
Acad. Sci. U.S.A. 2002, 99, 3240.
7. Multiple patents describing small molecule MCHr1 antag-
onists have published recently. For excellent reviews on
the subject, see the following: (a) Kowalski, T. J.;
McBriar, M. D. Expert Opin. Invest. Drugs 2004, 13,
1113; (b) Browning, A. Expert Opin. Ther. Pat 2004, 14,
313; (c) Collins, C. A.; Kym, P. R. Curr. Opin. Invest.
Drugs 2003, 4, 386.
8. For example, see: (a) Borowsky, B.; Durkin, M. M.;
Ogozalek, K.; Marzabadi, M. R.; DeLeon, J.; Lagu, B.;
Heurich, R.; Lichtblau, H.; Shaposhnik, Z.; Daniewska,
I.; Blackburn, T. P.; Branchek, T. A.; Gerald, C.; Vaysse,
P. J.; Forray, C. Nat. Med. 2002, 8, 779; (b) Takekawa, S.;
Asami, A.; Ishihara, Y.; Terauchi, J.; Kato, K.; Shimom-
ura, Y.; Mori, M.; Murakoshi, H.; Kato, K.; Suzuki, N.;
Nishimura, O.; Fujino, M. Eur. J. Pharmacol. 2002, 438,
129; (c) Souers, A. J.; Gao, J.; Brune, M.; Bush, E.;
Wodka, D.; Vasudevan, A.; Judd, A. S.; Mulhern, M. M.;
Brodjian, S.; Dayton, B.; Shapiro, R.; Hernandez, L. E.;
Marsh, K. C.; Sham, H. L.; Collins, C. A.; Kym, P. R. J.
Med. Chem. 2005, 48, 1318; (d) Kym, P. R.; Iyengar, R.
R.; Souers, A. J.; Lynch, J. K.; Judd, A. S.; Gao, J.;
Freeman, J. C.; Mulhern, M. M.; Zhao, G.; Vasudevan,
A.; Wodka, D.; Blackburn, C.; Brown, J.; Che, J. L.;
Cullis, C.; Lai, S. J.; LaMarche, M.; Marsilje, T.; Roses,
J.; Sells, T.; Geddes, B.; Govek, E.; Patane, M.; Fry, D.;
Dayton, B. D.; Brodjian, S.; Falls, H. D.; Brune, M.;
Bush, E.; Shapiro, R.; Knourek-Segel, V.; Fey, T.;
McDowell, C.; Reinhart, G. A.; Preusser, L. C.; Marsh,
K.; Hernandez, L.; Sham, H. L.; Collins, C. A. J. Med.
Chem. 2005, 48, 5888; (e) Kym, P. R.; Souers, A. J.;
Campbell, T. J.; Lynch, J. K.; Judd, A. S.; Iyengar, R.;
Vasudevan, A.; Gao, J.; Freeman, J. C.; Wodka, D.;
Mulhern, M.; Zhao, G.; Wagaw, S.; Napier, J. J.;
Brodjian, S.; Dayton, B. D.; Reilly, R. M.; Segreti, J.;
Fryer, R. M.; Preusser, L. C.; Reinhart, G. A.; Hernandez,
L.; Marsh, K. C.; Sham, H. L.; Collins, C. A.; Polakowski,
J. S. J. Med. Chem. 2006, 49, 2339; (f) McBriar, M. D.;
Guzik, H.; Shapiro, S.; Paruchova, J.; Xu, R.; Palani, A.;
Clader, J. W.; Cox, K.; Greenlee, W. J.; Hawes, B. E.;
Kowalski, T. J.; O’Neill, K.; Spar, B. D.; Weig, B.;
Weston, D. J.; Farley, C.; Cook, J. J. J. Med. Chem. 2006,
49, 2294.
b
b
AUC0ꢀ1
Cmax
C12h
t1/2
Plasma
Brain
3154 (ng h/mL)
1378 (ng h/g)
598 ng/mL
185 ng/g
38 ng/mL
75 ng/g
2 h
8 h
a All values are mean values (n = 3 unless specified otherwise). Inter-
animal variability was less than 30%. Compounds are dosed in DIO
mice at 10 mg/kg, po in a vehicle containing 1% Tween 80 and water.
b The three mice with highest plasma and brain concentrations were
averaged to provide the peak plasma and brain concentrations
(Cmax), respectively. The mean plasma or brain concentration data
were submitted to multi-exponential curve fitting using WinNonlin.
The area under the mean concentration–time curve from 0 to t h
(time of the last measurable concentration) after dosing (AUC0ꢀt
)
was calculated using the linear trapezoidal rule for the concentra-
tion–time profile. The residual area was extrapolated to infinity,
determined as the final measured mean concentration (Ct) divided by
the terminal elimination rate constant (b), and was added to AUC0ꢀt
to produce the total area under the curve (AUC0ꢀ1).
might lead to a steady-state CNS concentration suffi-
cient to induce MCHr1-mediated weight loss while lim-
iting plasma drug exposure.
To test the pharmacokinetic aspect of this hypothesis,
compound 16a was orally dosed at 10 mpkqd to DIO
mice fed a high fat diet for 2 weeks.17 Day 14 drug levels
indicated that while the plasma drug concentration
cleared from a one-hour concentration of 0.77 lg/mL
to a 16-h concentration of 0.10 lg/mL, a constant
(C1h = C16h) concentration of 0.6 lg/g had been reached
in the brain. However, we were concerned by the non-
linear relationship between the acute (0.185 lg/g) and
chronic brain distributions. Particularly, the static nat-
ure of the latter prompted us to analyze more closely
the drug distribution in other tissues, where we found
significant accumulation in the heart and thigh.18 As this
phenomenon was likely secondary to the di-basic19 char-
acter of 16a, an aspect of the entire sub-series that was
seemingly critical to deliver off-target (hERG channel)
selectivity, work in this area was discontinued.
Acknowledgments
The authors thank Christopher Ogiela and Dr. Dennis
Fry for preparing the IMR-32 cells and aiding with
the execution of the binding and functional assays, Paul
Richardson and J.J. Jiang for MCH production, and
Dr. James J. Napier of Process Chemistry for generous
supply of intermediate 7.
9. For reviews of the hERG channel and QT interval
prolongation, see: (a) Finalyson, K.; Witchel, H. J.;
McCulloch, J.; Sharkey, J. Eur. J. Pharmacol. 2004, 500,
129; (b) Fermini, B.; Fossa, A. A. Nat. Rev. Drug Discov.
2003, 2, 439.
10. Lynch, J. K.; Freeman, J. C.; Judd, A. S.; Iyengar, R.;
Mulhern, M.; Zhao, G.; Napier, J. J.; Wodka, D.;
Brodjian, S.; Dayton, B. D.; Falls, D.; Ogiela, C.; Reilly,
R. M.; Campbell, T. J.; Polakowski, J. S.; Hernandez, L.;
Marsh, K. C.; Shapiro, R.; Knourek-Segel, V.; Droz, B.;
Bush, E.; Brune, M.; Preusser, L. C.; Fryer, R. M.;
Reinhart, G. A.; Houseman, K.; Diaz, G.; Mikhail, A.;
Limberis, J. T.; Sham, H. L.; Collins, A. A.; Kym, P. R.
J. Med. Chem. 2006, ASAP, doi:10.1021/jm060683e.
11. Fry, D.; Dayton, B. D.; Brodjian, S.; Ogiela, C.;
Sidorowicz, H.; Frost, L. J.; McNally, T.; Reilly, R. M.;
Collins, C. A. Int. J. Biochem. Cell Biol. 2006, 38, 1290.
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´
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