Design and optimization of quinazoline derivatives as melanin concentrating hormone receptor 1 (MCHR1) antagonists: Part 2

Article abstract of DOI:10.1016/j.bmcl.2012.03.049

Melanin concentrating hormone receptor 1 (MCHR1) antagonists have potential for the treatment of obesity and several CNS disorders. In the preceding article, we have described a novel series of quinazolines as MCHR1 antagonists and demonstrated in vivo proof of principle with an early lead. Herein we describe the detailed SAR and SPR studies to identify an optimized lead candidate having good efficacy in a sub-chronic DIO model with a good cardiovascular safety window.

Full text of DOI:10.1016/j.bmcl.2012.03.049

Bioorganic & Medicinal Chemistry Letters 22 (2012) 3163–3167
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Design and optimization of quinazoline derivatives as melanin
concentrating hormone receptor 1 (MCHR1) antagonists: Part 2 q
Sanjita Sasmal a, D. Balasubrahmanyam a, Hariprasada R. Kanna Reddy a, Gade Balaji a, Gujjary Srinivas a,
Srisailam Cheera a, Chandrasekhar Abbineni a, Pradip K. Sasmal a, , , Ish Khanna a, V.J. Sebastian a,
⇑
Vikram P. Jadhav a, Manvendra P. Singh a, Rashmi Talwar a, J. Suresh a, Dhanya Shashikumar a,
K. Harinder Reddy a, V. Sihorkar a, Thomas M. Frimurer b, Øystein Rist b, Lisbeth Elster b,
Thomas Högberg b, ,à
⇑
a Discovery Research, Dr. Reddy’s Laboratories Ltd, Bollaram Road, Miyapur, Hyderabad 500049, India
b 7TM Pharma A/S, Fremtidsvej 3, DK-2970 Hørsholm, Denmark
a r t i c l e i n f o
a b s t r a c t
Article history:
Melanin concentrating hormone receptor 1 (MCHR1) antagonists have potential for the treatment of
obesity and several CNS disorders. In the preceding article, we have described a novel series of quinazo-
lines as MCHR1 antagonists and demonstrated in vivo proof of principle with an early lead. Herein we
describe the detailed SAR and SPR studies to identify an optimized lead candidate having good efficacy
in a sub-chronic DIO model with a good cardiovascular safety window.
Received 22 January 2012
Revised 11 March 2012
Accepted 13 March 2012
Available online 23 March 2012
Ó 2012 Elsevier Ltd. All rights reserved.
Keywords:
Melanin concentrating hormone (MCH)
Quinazolines
MCHR1 antagonists
hERG
Obesity
The hormone MCH, a 19-amino acid cyclic neuropeptide ex-
pressed predominantly in the lateral hypothalamus and zona in-
certa,1 is an important mediator of energy homeostasis.2 The
evidence for the role of MCH and the MCHR1 in body weight and
feeding regulation is abundant and supports the hypothesis that
MCHR1 antagonists should provide a novel treatment for obesity.3
In the preceding paper4 we disclosed our initial findings of quinaz-
oline derivatives as MCHR1 antagonists. The two representative
compounds 1 and 2 (Fig. 1) showed MCHR1 functional antagonism
of 33 and 16 nM, respectively, and in vivo proof of principle was
demonstrated with compound 2. However, both compounds
showed significant hERG inhibition and majority of the compounds
showed poor microsomal stability. The oxymethylene linker is
associated with the poor metabolic stability. After exploring vari-
ous linkers, cinnamides were found to convey reasonable potency
and microsomal stability. Thus extensive SAR was triggered to
optimize the cinnamide series to suppress the hERG interaction.5
The approaches explored included (i) modulation of overall basi-
city, (ii) increased polar surface area, and (iii) lowered lipophilicity.
We describe herein our efforts on structural modifications of this
chemotype to identify a lead optimized candidate.
The target compounds (Tables 1–3) were synthesized as out-
lined in Schemes 1–7. Carbonyl compounds I were converted to
various cinnamic acids II, which were coupled with the amino
intermediates III4 to afford 3–21 (Scheme 1). Compounds 22–24
were prepared following Scheme 2. Piperidines IV and VI derived
R1
N
N
O
R2
O
N
q
N
H
DRL-PP Publication No. 730.
Corresponding authors. Tel.: +91 40 4434 6865 (P.K.S.); +45 44 94 58 88 (T.H.).
⇑
CH3
F3CO
E-mail addresses: pradipks@drreddys.com, sasmalpk@yahoo.co.in (P.K. Sasmal),
thomas.hogberg@leo-pharma.com (T. Högberg).
OH
1: NR1R2 = N
2: NR1R2 = N
N
O
Present address: Dr. Reddy’s Laboratories Ltd, Innovation Plaza, Bachupally,
Hyderabad 500090, India.
à
Present address: LEO Pharma, Chemical Research, Industriparken 55, DK-2750
Ballerup, Denmark.
Figure 1. Potent MCHR1 antagonists.
0960-894X/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bmcl.2012.03.049

3164
S. Sasmal et al. / Bioorg. Med. Chem. Lett. 22 (2012) 3163–3167
Table 1
Table 3
Human MCHR1 binding and functional activity of compounds 3–24
Human MCHR1 binding and functional activity of compounds 35–60
OH
R2
R2
N
R3
N
N
R1
O
N
N
R1
O
N
N
H
N
N
H
CH3
X
CH3
X
Compd
X
R1
R2
hMCHR1a (IC50
)
a
Compd
X
R1
R2
R3
hMCHR1 (IC50)
SPAb (nM)
IP3b (nM)
SPAb (nM)
IP3b (nM)
3
4
5
6
7
OCF3
Cl
Cl
OCF3
OCF3
Cl
Cl
Me
CF3
OMe
CHF2
OCHF2
o,p-DiCl
H
H
Me
H
Me
H
Me
H
H
H
H
H
H
H
62
107
670
208
354
149
532
344
232
116
122
201
620
40
73
227
74
196
16
340
107
83
59
62
63
575
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Cl
H
H
H
H
H
Me
H
Me
H
H
H
H
H
H
H
H
H
H
Me
H
H
H
–(CH2)2O(CH2)2–
–(CH2)2O(CH2)2–
–COCH2O(CH2)2–
–CO(CH2)4–
–CO(CH2)3–
–CO(CH2)3–
–CO(CH2)3–
–CO(CH2)3–
–SO2(CH2)3–
16
10
30
51
11
69
74
81
4
94
41
68
66
21
145
280
225
31
112
41
45
26
32
45
91
105
17
13
13
15
12
39
20
43
16
35
31
18
31
21
26
170
45
14
34
27
19
6
OCF3
OCF3
OCF3
OCF3
OCF3
Cl
cPr
cPr
cPr
cPr
cPr
cPr
cPr
cPr
cPr
cPr
8
9
10
11
12
13
14
15
Cl
OCF3
OCF3
OCF3
OCF3
OCF3
OCF3
OCF3
OCF3
Cl
Cl
Cl
Cl
Cl
–CO(CH2)2CO–
–COO(CH2)2–
–COOCMe2CH2–
–CONH(CH2)2–
–CONMe(CH2)2–
–SO2NH(CH2)2–
–SO2NMe(CH2)2–
H
H
16
H
cPr
1800
1450
N
17
18
19
20
21
22
23
24
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
H
H
H
H
H
H
H
H
Ph
1095
206
171
245
270
150
220
245
86
54
89
91
255
24
cBu
H
COcPr
iPr
nPr
H
SO2Me
H
SO2Me
Et
H
H
H
H
Me
Me
H
COCH2OH
COCH2OMe
COCH2OH
COCH2OMe
COCH2OMe
COCH2OH
SO2NMe2
CH2Ac
(CH2)2OH
(CH2)2OMe
230
220
OCF3
OCF3
OCF3
OCF3
OCF3
H
H
H
H
14
34
56
31
a
Values are mean of at least two experiments.
See Ref. 4 for the protocols.
b
a
Values are mean of at least two experiments.
See Ref. 4 for the protocols.
b
Table 2
Human MCHR1 binding and functional activity of compounds 25–34
R1
OH
R2
N
N
R1
R2
O
N
COOH
N
N
N
H
b
3-21
II
+
CH3
N
X
X
X
H2N
a
III
Compd
X
R1
R2
hMCHR1 (IC50
)
a
R1
R1 = H, Me
R2 = H, Et, nPr, iPr, cPr, cBu
X = Cl, Me, CF3, CHF2, OMe, OCF3, OCHF2, o,p-diCl
SPAb (nM)
IP3b (nM)
O
25
26
27
28
29
30
31
32
33
34
Cl
Cl
Cl
c-Pentyl
c-Pentyl
Me
(CH2)2OH
(CH2)2OH
(CH2)3OH
399
850
555
36
290
169
54
61
63
20
57
4125
182
30
255
142
32
23
26
35
I
H
H
iPr
H
H
H
H
H
OCF3
OCF3
OCF3
OCF3
OCF3
OCF3
OCF3
Scheme 1. Reagents and conditions: (a) (i) Ethyl 2-(diethoxyphosphoryl)acetate,
NaH, THF, 0 °C to rt, 2 h, 25–62%; (ii) LiOH, MeOH/H2O, rt, 16 h, 45–76%; (b) HOBt,
EDCI, Et3N, CH2Cl2, rt, 6 h, 48–65%.
(CH2)3OH
(CH2)2NHMs
(CH2)3NHMs
(CH2)2NHCOcPr
(CH2)3NHCOcPr
(CH2)3CONHcPr
The quinazoline VII was reacted with various di-amines and
amino acids to furnish intermediate X (Scheme 4). The amino
group was converted to sulfonamides and amides whereas the car-
boxyl end was converted to reverse amides to realize the desired
target compounds 30–34.
a
Values are mean of at least two experiments.
See Ref. 4 for the protocols.
b
from 1-benzylpiperidin-4-onewere treated with VII. The resulting
products were subjected to two-steps protocols, viz., reduction of
the nitro group to amine followed by coupling with p-chlorocin-
namic acid to furnish the target compounds.
Displacement of the 2-chloro substituent of quinazoline VII
with amino functionality provided intermediates VIII and IX which
were manipulated using standard protocols to desired target mol-
ecules 25–29 (Scheme 3).
Compounds 35–48 were prepared following Scheme 5. The
piperidineaminols XI were converted to morpholinone XII and car-
bamate derivatives XIII. Various 4-piperidine derivatives XIV–XVII
were prepared following literature procedure.6 All these piperi-
dines were coupled with VII and the resulting products were
subsequently converted to desired target structures. Compound
XIa was treated with Burgess-type reagent XVII under Nicolaou’s
reaction conditions7 to afford the sulfamides XIX (Scheme 6).

S. Sasmal et al. / Bioorg. Med. Chem. Lett. 22 (2012) 3163–3167
3165
HO
R
a
OH
R
O
X
O
NBn
NBn
NH
HN
O
R
R
N
Cl
a, b
c, b
O
HN
N
O
N
N
Y
b
O
IV
N
n
+
O2N
N
Boc
XIVa: X = H2, Y = O, n = 2
XIVb: X = O, Y = CH2, n = 2
XIVc: X = O, Y = CH2, n = 1
HO
HO
VII
d
N
H
N
H
XIa : R = H
NH
VI
XIb : R = Me
e
RO
RO
XIII : R = H, Me
XII
Va : R = H
c
O
O
O
22-24
O
R1
Vb : R = Me
S
N
N
HN
N
HN
N
HN
Scheme 2. Reagents and conditions: (a) LDA, acetone, THF, À78 °C, 2 h, 76%; (b) (i)
LDA, EtOAc, THF, À78 °C, 2 h, 41%; (ii) LAH, THF, 0 °C, 2 h, 52%; (c) NaH, THF, MeI,
0 °C to rt, 12 h, 23%; (d) 10% Pd/C, H2, MeOH, 16 h, 92–95%; (e) (i) Et3N, MeOH,
reflux, 2 h, 81–85%; (ii) 10% Pd/C, H2, EtOH, 2 h, 81–97%; (iii) p-chlorocinnamic acid,
HOBt, EDCI, Et3N, CH2Cl2, rt, 16 h, 32–61%.
O
XVII : R1 = H, Me
XV
VII
XVI
d
XII-XVII
+
35-48
Scheme 5. Reagents and conditions: (a) (i) Bromoacetyl bromide, THF, 0 °C to rt,
2 h, 50%; (ii) NaH, THF, rt, 2 h, 60%; (b) TFA, CH2Cl2, rt, 4 h, 90–94%; (c) Im2CO,
dioxane, 24 h, 54–60%; (d) (i) Et3N, MeOH, reflux, 2 h, 60–85%; (ii) 10% Pd/C, H2,
EtOH, 2 h, 86–97%; (iii) p-Cl/OCF3-cinnamic acid, HOBt, EDCI, Et3N, CH2Cl2, rt, 6 h,
45–68%.
R1
N
H
N
R1
N
N
b, c
b, d
a
a
VII
VII
25
26
+
N
N
O2N
O2N
R1 = Me, CH2CH2OH
VIII
IX
R2
N
R2
OH
n
b, d
OH
O
O
+
N
H
27-29
O
N
a
n
N
O
NBoc
S
XIa
CbzN
+
Et3N
OBn
S
R2 = H, iPr; n = 1, 2
O
XVII
XIX
b
N
c
Scheme 3. Reagents and conditions: (a) Et3N, MeOH, reflux, 2 h, 60–90%; (b) 10%
Pd/C, H2, EtOH, 2 h, 86–97%; (c) p-chlorocinnamic acid, HOBt, EDCI, Et3N, CH2Cl2, rt,
6 h, 65%; (d) (i) p-Cl/OCF3-cinnamic acid, HOBt, EDCI, Et3N, CH2Cl2, rt, 6 h; (ii) LiOH,
THF/EtOH/water (4:2:1), rt, 12 h, 40–55% (two steps).
NR
N
S
O
O
N
d
49-50
N
XXa : R = H
XXb: R = Me
O2N
H
N
N
a
X
n
X
VII
+
H2N
n
Scheme 6. Reagents and conditions: (a) THF, reflux, 16 h, 61%; (b) (i) TFA, CH2Cl2,
rt, 4 h, 64%; (ii) VII, Et3N, MeOH, reflux, 3 h, 36%; (iii) NaOH, THF/water (3:1), rt, 2 h,
99%; (c) K2CO3, DMF, MeI, rt, 1 h, 56%; (d) (i) 10% Pd/C, H2, EtOH, 2 h, 64–90%; (ii) p-
trifluoromethoxycinnamic acid, HOBt, EDCI, Et3N, CH2Cl2, rt, 12 h, 23–32%.
N
O2N
X = NH2, COOH
n = 1,2
X
(X = NH2)
b, c
(X = CO2H)
d, c
e, c
is, 2–10 lM with few exceptions, but this could be improved by
salt formation as exemplified for 8 (see below).
34
32-33
30-31
The Table 1 shows a summary of results obtained from the 4-
hydroxy-4-alkyl piperidine derivatives related to compound 1
lacking a distal aliphatic amine (cf. compound 2). Amongst various
alkyl substitutions, c-Pr was found to be optimal. For example, the
c-Bu has inferior metabolic stability (see below). A limited SAR
study by changing aromatic substitution in the cinnamide largely
corroborated our previous findings in the related quinoline series
as the more bulky substituent in 16 had inferior potency compared
to the other substituents irrespective of their electronic proper-
ties.9 The potent 4-chloro derivative 8 displayed good microsomal
Scheme 4. Reagents and conditions: (a) Et3N, MeOH, reflux, 2 h, 60–85%; (b) MsCl,
Et3N, CH2Cl2, 2 h, 86%; (c) (i) 10% Pd/C, H2, EtOH, 2 h, 85–95%; (ii) p-trifluorometh-
oxycinnamic acid, HOBt, EDCI, Et3N, CH2Cl2, rt, 6 h, 25–45%; (d) cyclopropanecar-
bonyl chloride, Et3N, CH2Cl2, 16 h, 52%; (e) cyclopropyl amine, HOBt, EDCI, Et3N,
CH2Cl2, rt, 16 h, 70%.
Deprotection of N-Boc followed by coupling with VII led to com-
pound XXa. Removal of the Cbz group followed by methylation
furnished compound XXb. Both XXa and XXb were subjected to
reduction followed by coupling with p-trifluoromethoxycinnamic
acid under HOBt/EDCI conditions to provide compounds 49 and 50.
The syntheses of compounds 51–60 are outlined in Scheme 7.
The tert-butyl 4-aminopiperidine-1-carboxylate and tert-butyl
4-(methylamino)piperidine-1-carboxylate were converted to piper-
idines XXI and XXII whereas XXIII was obtained from 1-benzylpi-
peridin-4-amine. Reaction of 2-chloroquinazoline derivative VII
with piperidines XXI–XXIV followed by further manipulation using
standard protocols furnished the desired target structures.
stability and hERG IC50 of 5.6 lM. Compared to cinnamides, all b-
methylcinnamides showed decreased potency as exemplified with
5, 7 and 9. Replacing cyclopropyl group with acetylmethyl group as
in compound 22 retained MCHR1 potency but the compound
showed somewhat surprisingly high hERG inhibition (54% at
1 lM concentration). The other more substituents hydroxyethyl
and methoxyethyl groups as in 23 and 24 resulted in reduced
potency.
The binding affinity for the MCHR1 of the target compounds
was assessed in the SPA based [125I]MCH binding screen4 using
Chinese hamster ovary (CHO-K1) cell membranes expressing hu-
man recombinant MCHR1 receptors. The functional antagonism
was measured in an IP3 SPA-YSI assay.4 Selected compounds were
chosen for hERG8 and microsomal stability studies (Table 4). In
general the compounds displayed a rather limited solubility, that
We next turned our attention to replace the eastern piperidine
moiety with acyclic amines carrying various polar ends (Table 2).
Though the potency of compound 25 carrying a N-methylcyclopen-
tylamine group was moderate, the corresponding 2-(cyclopentyla-
mino)ethanol counterpart as in 26 was detrimental to MCHR1
potency, which was supported by modeling studies indicating
room for one larger nitrogen substituent (cf. a detailed description

3166
S. Sasmal et al. / Bioorg. Med. Chem. Lett. 22 (2012) 3163–3167
Table 5
O
Efficacy studies in DIO mice and the steady state exposure of select MCHR1
antagonists
R1
H
R1
OH
N
N
N
d, e, f, g
a, b
Compd Weight reduction at
day 14
Plasma exposure at
steady state
Brain exposure at
steady state
VII
54, 56, 59
+
N
H
AUCss
M.h)
Cssmax
M)
AUC
M.h)
Cmax
M)
Boc
(R1 = H, Me)
c, b
XXI
(
l
(
l
(
l
(
l
NHR
HN
8a
37b
39b
45b
13% @100 mg/kg q.d 104
12% @30 mg/kg b.i.d 312
14% @30 mg/kg b.i.d 385
12% @30 mg/kg b.i.d 284
5.9
30.2
2.1
6.3
5.6
3.7
16.5
17.7
12.7
103.9
95.1
67.6
XXIVa: R = COcPr
XXIVb: R = SO2Me
O
R1
OMe
NH2
N
a
CMC/Tween 80 suspension.
Micronized suspension.
h
b
NHSO2NMe2
HN
N
H
N
XXII
XXIII
Bn
4
2
d, f
VII
+
XXII-XXIV
51-53, 55, 57-58, 60
0
Scheme 7. Reagents and conditions: (a) 2-Hydroxyacetic acid, HOBt, EDCI, Et3N,
CH2Cl2, rt, 24 h, 35–42%. (b) TFA, CH2Cl2, 0 °C, 2 h, 88–93%; (c) 2-methoxyacetic
acid, HOBt, EDCI, Et3N, CH2Cl2, rt, 16 h, 43–50%; (d) Et3N, MeOH, reflux, 2 h, 60–85%;
(e) TBSCl, imidazole, CH2Cl2, 0 °C to rt, 24 h, 80%; (f) (i) 10% Pd/C, H2, EtOH, 2 h, 85–
94%; (ii) p-Cl/OCF3-cinnamic acid, HOBt, EDCI, Et3N, CH2Cl2, rt, 6 h, 48–64%; (g)
TBAF, CH2Cl2, 0 °C to rt, 3 h, 44–62%; (h) (i) Me2NSO2Cl, Et3N, CH2Cl2, 41%; (ii) 10%
Pd/C, H2, EtOH, 2 h, 78%.
-2
-4
-6
-8
-10
-12
-14
Table 4
hERG activity and microsomal stabilities of representative MCHR1 antagonists
Compd IC50 IP3
(nM)
% Inhibition of hERG at 1 uM/ Microsomal stabilitya
hERG IC50 (uM)
mice/human
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15
1
2
3
6
8
33
16
40
74
16
62
47
24
57
30
32
23
26
35
17
13
12
39
20
16
35
31
31
21
45
14
19
14
34
58%
78%
3.3
24%
5.6
36/—b
45/59
86/—
67/—
83/67
64/—
12/—
78/—
12/—
74/—
58/—
38/—
87/—
34/—
47/—
80/57
85/76
86/—
83/50
83/85
40/—
74/85
89/83
94/33
85/—
56/—
50/—
57/58
69/69
Day(s) of Treatment
Figure 2. Effect on the body weight of DIO C57BL/6J mice after subchronic oral
administration of 8 (N30 mg/kg, q.d; .100 mg/kg, q.d) for 14 days versus vehicle
control animals (d) (n = 12).
13
18
22
25
28
31
32
33
34
35
37
39
40
41
43
44
45
47
48
51
52
55
57
58
2.5
26%
54%
—
59%
39%c
69%
37%d
—
provided compound 27 which showed moderate potency. Inter-
changing the chlorine with a OCF3 group at western end as in 28
showed an improved potency of 30 nM in functional assay. Further
N-alkylation on 28 as in compound 29 led to decreased potency in
accordance with the restrictions of the binding cavity to accommo-
date two sizeable substituents. Replacement of hydroxyl function-
ality with sulfonamides, amides and reverse amides are well
tolerated in this scaffold. Despite good MCHR1 potency, all potent
compounds from this series showed either poor microsomal stabil-
ity (25, 32, 34) or significant inhibition of hERG (28, 31, 32), con-
trary to what we expected by the introduction of the polar
motifs. Thus we moved back to the SAR exploration at the 4th
position of eastern piperidine.
To reduce the basicity of 4-aminopiperidine derivatives, com-
pounds with lactam, cyclic carbamate, cyclic sulfonamide, cyclic
urea, imide and cyclic sulfamide were investigated. Most cyclic
(35–50) compounds were found to be quite potent and the b-
methylcinnamides displayed comparable potency (39 vs 40 and
41 vs 42). In general, the compounds also had a good microsomal
stability (except 44) and improved hERG profile, albeit the b-meth-
ylcinnamides less so compared to the corresponding cinnamides.
Minor structural differences (cf. 47 and 48) also were found to
influence hERG differently. The secondary amines 51–57 were also
potent but they showed higher inhibition of hERG channel.
Several of the potent MCHR1 antagonists with good metabolic
stability and improved separation over hERG were identified for fur-
ther profiling. Based on the overall data (potency and ADME), com-
pounds 8, 37, 39 and 45 were chosen for efficacy studies. The Table 5
shows the results from a diet induced obesity (DIO) mouse model
using C57BL/6J mice. All compounds showed statistically significant
81%
20%
5%e
f
23%
17%
—
15%
g
7%
55%
h
1.2
25%
i
a
b
c
d
e
f
% Remaining at 30 min.
Not tested.
79% at 3 uM.
63% at 3 uM.
41% at 5 uM.
52% at 3 uM.
45% at 3 uM.
54% at 3 uM.
48% at 3 uM.
g
h
i
of the receptor models and flexible docking methodology in the
preceding paper).4 Accordingly, removal of the cyclopentyl group

S. Sasmal et al. / Bioorg. Med. Chem. Lett. 22 (2012) 3163–3167
3167
Table 6
Plasma PK profile of compound 8 administered as base or mesylate salt
References and notes
1. Nahon, J. L. Biology 2006, 329, 623.
Species Form Dose (mg/
kg)
Route AUC(0–24)
MÁh)
Cmax/C0
M)
t1/2
(h)
2. (a) Hervieu, G. Expert Opin. Ther. Targets 2006, 10, 211; (b) Shimazaki, T.;
Yoshimizu, T.; Chaki, S. CNS Drugs 2006, 20, 801; (c) Rivera, G.; Bocanegra-
Garcia, V.; Galiano, S.; Cirauqui, N.; Ceras, J.; Perez, S.; Aldana, I.; Monge, A. Curr.
Med. Chem. 2008, 1025, 15; (d) Kowalski, T. J.; Sasikumar, T. BioDrugs 2007, 21,
311.
(l
(l
Mice
Rat
Rat
Dog
Dog
Basea 30
po
po
po
po
iv
33.4
26.6
79.6
37.7
43.5
2.1
2.4
7.8
2.5
9.9
8.1
12.7
9.3
19.1
8.7
Base
Saltb
Salt
30
30
5
3. (a) Ludwig, D. S.; Tritos, N. A.; Mastaitis, J. W.; Kulkarni, R.; Kokkotou, E.;
Elmquist, J.; Lowell, B.; Flier, J. S.; Maratos-Flier, E. J. Clin. Invest. 2001, 107, 379;
(b) Shimada, M.; Tritos, N. A.; Lowell, B. B.; Flier, J. S.; Maratos-Flier, E. Nature
1998, 396, 670; (c) 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; (d) 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.; MacIntyre, D. E.;
Van der Ploeg, L. H. T.; Qian, S. Proc. Natl. Acad. Sci. U.S.A. 2002, 99, 3240; (e)
Hervieu, G. Expert Opin. Ther. Targets 2003, 7, 495; (f) Chaki, S.; Funakoshi, T.;
Hirota-Okuno, S.; Nishiguchi, M.; Shimazaki, T.; Iijima, M.; Grottick, A. J.;
Kanuma, K.; Omodera, K.; Sekiguchi, Y.; Okuyama, S.; Tran, T. A.; Semple, G.;
Thomsen, W. J. Pharmacol. Exp. Ther. 2005, 313, 831.
4. Sasmal, S.; Balaji, G.; Kanna Reddy, H. R.; Balasubrahmanyam, D.; Srinivas, G.;
Kyasa, S.; Sasmal, P. K.; Khanna, I.; Talwar, R.; Suresh, J.; Jadhav, V. P.; Muzeeb,
S.; Shashikumar, D.; Reddy, K. H.; Sebastian, V. J.; Frimurer, T. M.; Rist, Ø.;
Elster, L.; Högberg, T. Bioorg. Med. Chem. Lett. 2012, 22. http://dx.doi.org/
10.1016/j.bmcl.2012.03.050.
5. For recent reviews on hERG, see: (a) Staudacher, I.; Schweizer, P. A.; Katus, H.
A.; Thomas, D. Curr. Opin. Drug. Discov. Devel. 2010, 13, 23; (b) Wulff, H.; Castle,
N. A.; Pardo, L. A. Nat. Rev. Drug Disc. 2009, 8, 982; (c) Pollard, C. E.; Valentin, J.
P.; Hammond, T. G. Br. J. Pharmacol. 2008, 154, 1538; (d) Finlayson, K.; Witchel,
H. J.; McCulloch, J.; Sharkey, J. Eur. J. Pharmacol. 2004, 500, 129.
6. (a) Verschueren, W. G.; Dierynck, I.; Amssoms, K. I. E.; Hu, L.; Boonants, P. M. J.
G.; Pille, G. M. E.; Daeyaert, F. F. D.; Hertogs, K.; Surleraux, D. L. N. G.;
Wigerinck, P. B. T. P. J. Med. Chem. 1930, 2005, 48; (b) PCT WO2005113504.
7. Nicolaou, K. C.; Snyder, S. A.; Longbottom, D. A.; Nalbandian, A. Z.; Huang, X.
Chem. Eur. J. 2004, 10, 5581.
8. HEK293 cells stably expressing hERG potassium channels were voltage
clamped using automated Port-A-Patch electrophysiology system. Test items
were dissolved in DMSO and diluted with external recording buffer. Cells were
exposed to test concentration for approximately 5 min or till a steady state
block was reached at 20–35 °C. Each cell acted as its own control. Cisapride
Salt
6
a
Solubility in FaSSIF at 0.5 h (pH 6.5) 1.7
Solubility in FaSSIF at 0.5 h (pH 6.5) 11.2
lM.
b
lM.
weight loss after chronic treatment for 14 days. Figure 2 shows the
effect on the body weight of DIO mice after subchronic oral admin-
istration of 8 at a dose of 30 and 100 mg/kg, q.d.10 The steady state
exposure of all compounds were measured at the end of the efficacy
studies and the results are shown in Table 5. Considering brain expo-
sure required to elicit the comparable weight reductions, compound
8 was found to be best from this lot. The mouse and human plasma
protein binding of these compounds are above 99.5% and the
requirement of very high exposure to demonstrate efficacy might
be linked to high brain tissue binding.
Due to poor solubility of the compounds, several salts were
investigated. Considering dissolution rate and overall solubility,
the mesylate salt of compound 8 was chosen for further studies
as it displayed a sixfold higher solubility in FaSSIF (Fasted State
Simulated Intestinal Fluid) (Table 6).
Table 6 shows the plasma PK summary of compound 8 and its
mesylate salt in mice, rat and dog. As expected the mesylate salt
showed threefold increase in exposure compared to free base when
tested in rat. This data encouraged us to investigate the cardiovascu-
lar (CVS) safety in dog with compound 8 mesylate to evaluate the
significance of the hERG observations. Thus, compound 8 was tested
at 6 mg/kg dose for effects on cardiovascular functions in conscious
male Beagle dogs by intravenous infusion (15 min).11 It did not
cause any changes in heart rate, ECG parameters (QT, QTcV, PR and
QRS intervals), and blood pressure. The maximum plasma concen-
(1 lM) was used as an internal positive control to confirm the sensitivity of the
test system to hERG inhibition. The extent of inhibition of channel was
expressed as a percentage of the control response (minus the test compound).
9. Ulven, T.; Frimurer, T. M.; Receveur, J.-M.; Little, P. B.; Rist, Ø.; Nørregaard, P.;
Högberg, T. J. Med. Chem. 2005, 48, 5684.
10. Graph not shown for compounds 37, 39 and 45.
tration (Cmax) achieved in this study varied from 6.4 to 13.1
From the efficacy studies the Cmax at steady state in mouse was
5.9 M (Table 5). Considering 0.2% unbound drug in mouse and
lM.
11. Male dogs (n = 3) that were suitably trained for restraining (Dog slings) and
dosing procedures were allocated to the study and were dosed initially with
the Vehicle (30% w/v HPbCD; 2 ml/kg) to generate base line data. After 5 days
interval, they were administered with the test drug and monitored for effects
on the CVS functions. Electrocardiogram was recorded using Nihon Kohden
Cardiofax GEM electrocardiograph at the specified time points. At each time
point, the ECG was recorded for approximately 10 s. The chest lead rV2 was
used for the evaluation of drug effects on the ECG parameters. Blood pressure
was recorded using ‘MEDICARE automatic blood pressure recorder’ with arm
cuff, prior to dosing, and at the end of infusion (2–3 readings per time point).
Blood samples were collected immediately after each ECG recordings (8 min,
15 min, 30 min, 1, 2, 4, 6 and 24 h post dose) for estimation of drug levels in the
plasma. Parameters consisted of clinical signs, respiration rate, heart rate, ECG
intervals: QT interval (QT-I, uncorrected QT), QTcV (heart rate corrected QT
interval), PR interval (PR-I), QRS interval, ECG wave morphology, blood
pressure, rectal temperature and toxicokinetics (after each ECG recording: 8,
15, 30 min, 1, 2, 4, 6 and 24 h post dose).The ECG intervals for approximately
15 beats were manually counted and Mean and SD were calculated. The blood
pressure readings at each time point were averaged and mean values were
used for the evaluation. The test item related effects were determined based on
the magnitude of the differences in the parameters in relation to the respective
predose as well as the vehicle control values.
l
dog plasma (PPB 99.8% for both species), the ratio of hERG IC50 to un-
bound plasma concentration is 475. Thus the above studies in dog
demonstrated good cardiovascular safety window for compound 8.
In summary, we have identified several compounds belonging to
the quinazoline class as potent MCHR1 antagonists.12 The detailed
SAR and SPR studies undertaken led to better insights on the struc-
tural requirements for MCHR1 antagonism and hERG inhibition.
Selected compounds showed significant anti-obesity effect in a DIO
mice model after sub-chronic treatment. With compound 8 (DRL-
21816), it was demonstrated that the efficacy could be achieved with
a good cardiovascular safety window. Besides obesity, the disclosed
MCHR1 ligands13 might find their application in pharmacological
intervention of other diseases involving MCHR1 signaling pathways.
12. For other quinazoline derivatives as MCHR1 antagonists, see: (a) Kanuma, K.;
Omodera, K.; Nishiguchi, M.; Funakoshi, T.; Chaki, S.; Nagase, Y.; Iida, I.;
Yamaguchi, J.-I.; Semple, G.; Tran, T.-A.; Sekiguchi, Y. Bioorg. Med. Chem. 2006,
14, 3307; (b) Kanuma, K.; Omodera, K.; Nishiguchi, M.; Funakoshi, T.; Chaki, S.;
Semple, G.; Tran, T.-A.; Kramer, B.; Hsu, D.; Casper, M.; Thomsen, B.; Beeley, N.;
Sekiguchi, Y. Bioorg. Med. Chem. Lett. 2005, 15, 3853; (c) Kanuma, K.; Omodera,
K.; Nishiguchi, M.; Funakoshi, T.; Chaki, S.; Semple, G.; Tran, T.-A.; Kramer, B.;
Hsu, D.; Casper, M.; Thomsen, B.; Beeley, N.; Sekiguchi, Y. Bioorg. Med. Chem.
Lett. 2005, 15, 2565.
Acknowledgment
We thank the scientists of the analytical department of Discov-
ery Research for spectral data of all compounds.
Supplementary data
13. All compounds had purity >95% (by HPLC) with <3% of the single largest
impurity.
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.bmcl.2012.03.049.