Discovery of liver-targeted inhibitors of stearoyl-CoA desaturase (SCD1)

Article abstract of DOI:10.1016/j.bmcl.2012.11.075

Inhibitors based on a benzo-fused spirocyclic oxazepine scaffold were discovered for stearoyl-coenzyme A (CoA) desaturase 1 (SCD1) and subsequently optimized to potent compounds with favorable pharmacokinetic profiles and in vivo efficacy in reducing the desaturation index in a mouse model. Initial optimization revealed potency preferences for the oxazepine core and benzylic positions, while substituents on the piperidine portions were more tolerant and allowed for tuning of potency and PK properties. After preparation and testing of a range of functional groups on the piperidine nitrogen, three classes of analogs were identified with single digit nanomolar potency: glycine amides, heterocycle-linked amides, and thiazoles. Responding to concerns about target localization and potential mechanism-based side effects, an initial effort was also made to improve liver concentration in an available rat PK model. An advanced compound 17m with a 5-carboxy-2-thiazole substructure appended to the spirocyclic piperidine scaffold was developed which satisfied the in vitro and in vivo requirements for more detailed studies.

Full text of DOI:10.1016/j.bmcl.2012.11.075

Bioorganic & Medicinal Chemistry Letters 23 (2013) 791–796
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Discovery of liver-targeted inhibitors of stearoyl-CoA desaturase (SCD1)
Yongqi Deng a, , Zhiwei Yang a, , Gerald W. Shipps Jr. a,à, Sie-Mun Lo a, Robert West b, Joyce Hwa c,
⇑
Shuqin Zheng c, Constance Farley b, Jean Lachowicz b,§, Margaret van Heek c, Alan S. Bass b,
Dinesh P. Sinha b, Craig R. Mahon c, Mark E. Cartwright b
a Merck Research Laboratories, 320 Bent Street, Cambridge, MA 02141, United States
b Merck Research Laboratories, 2015 Galloping Hill Road, Kenilworth, NJ 07033, United States
c Merck Research Laboratories, RY 80Y-215 126 E. Lincoln Avenue, Rahway, NJ 07065-0900, United States
a r t i c l e i n f o
a b s t r a c t
Article history:
Inhibitors based on a benzo-fused spirocyclic oxazepine scaffold were discovered for stearoyl-coenzyme
A (CoA) desaturase 1 (SCD1) and subsequently optimized to potent compounds with favorable pharma-
cokinetic profiles and in vivo efficacy in reducing the desaturation index in a mouse model. Initial
optimization revealed potency preferences for the oxazepine core and benzylic positions, while substit-
uents on the piperidine portions were more tolerant and allowed for tuning of potency and PK properties.
After preparation and testing of a range of functional groups on the piperidine nitrogen, three classes of
analogs were identified with single digit nanomolar potency: glycine amides, heterocycle-linked amides,
and thiazoles. Responding to concerns about target localization and potential mechanism-based side
effects, an initial effort was also made to improve liver concentration in an available rat PK model. An
advanced compound 17m with a 5-carboxy-2-thiazole substructure appended to the spirocyclic piperi-
dine scaffold was developed which satisfied the in vitro and in vivo requirements for more detailed
studies.
Received 25 September 2012
Revised 16 November 2012
Accepted 20 November 2012
Available online 5 December 2012
Keywords:
Stearoyl-coenzyme A desaturase 1
Spirocyclic oxazepine
Liver-targeted inhibitors
Saturated fatty acids
Unsaturated fatty acids
Ó 2012 Elsevier Ltd. All rights reserved.
Stearoyl-coenzyme A (CoA) desaturase (SCD) is involved in the
de novo synthesis of monounsaturated fats from saturated fatty
acids.1 The major products of SCD are palmitoleoyl-CoA and
oleoyl-CoA, which are formed by desaturation of palmitoyl-CoA
and stearoyl-CoA, respectively. Oleate (an 18:1 fatty acid) is found
to be the major monounsaturated fatty acid of membrane phos-
pholipids, triglycerides, cholesteryl esters, wax esters and alkyl-
1,2-diacylglycerol.2 The ratio of unsaturated to saturated fatty
acids is one of the factors influencing membrane fluidity; its alter-
ation is important in a number of diseases, such as cancer, diabetes,
obesity, and neurological, vascular and heart disease.3–6 This ratio,
referred to as the desaturation index, can be analyzed for multiple
fatty acids in plasma including 18- and 16-carbon fatty acids, and
represents a potential biomarker of SCD1 inhibition.
isoforms have been found in humans, SCD1 and SCD5. In humans,
adipose and liver tissues show the highest expression of SCD1,
while brain and pancreatic tissues show highest expression of
SCD5.9 The overall sequence identity between human SCD1 and
SCD5 is 61%.
In vivo studies in mice support the central role of SCD in both
fatty acid metabolism and metabolic disorders. Mice strains with
a naturally occurring mutation in one of the SCD isoforms (SCD1)
and which have a targeted disruption in the SCD1 gene show
reduced fatty acid and triglyceride synthesis in response to a high
carbohydrate diet as compared to the amounts in wild type mice.10
Furthermore, mice which have a targeted disruption in the SCD1
gene show reduced body adiposity, increased insulin sensitivity
and resistance to diet-induced obesity.11 Mice which were injected
intraperitoneally with SCD1 targeted antisense oligonucleotide
showed improved insulin sensitivity and prevented occurrence of
obesity in the mice in response to high fat diets. In view of the
experimental evidence described above, modulation of SCD repre-
sents a promising therapeutic strategy for the treatment of obesity
and related metabolic disorders. However, given the wide distribu-
tion of SCD isoforms and their role in the fundamental process of
fatty acid desaturation, there have also been concerns over possible
mechanism-based side effects. Several companies have pursued
programs based on SCD1 inhibitors (Fig. 1).12–17 The major adverse
effects reported for some of the compounds were alopecia and
Depending on the species, highly homologous isoforms of SCD
exist, differing primarily in tissue distribution.7,8 For instance, in
mice, four SCD isoforms have been identified, while two SCD
⇑
Corresponding author. Present address: Merck Research Laboratories, 33 Avenue
Louis Pasteur, Boston, MA 02115, United States. Tel.: +1 617 992 3182.
E-mail address: yongqi.deng@merck.com (Y. Deng).
Current address: Invitrogen Corporation, 4979 Smith Canyon Court, San Diego, CA
92130, United States.
à
Current address: The New Venture Fund, Stoneham, MA 02180, United States.
Current address: Angiochem, 201 du Président-Kennedy, Montreal, QC, Canada
§
H2X 3Y7.
0960-894X/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bmcl.2012.11.075

792
Y. Deng et al. / Bioorg. Med. Chem. Lett. 23 (2013) 791–796
OMe
N
O
NH
HN
HN
O
N
F3C
Cl
O
N
O
N
O
1. Xenon
SCD1 IC50 = 100 nM
2. Abbott
SCD1 IC50 < 4 nM
O
N
H
N
O
N
N
O
CF3
HO
N
HO2C
N
N
O
Cl
N
N
Cl
3. CV Therapeutics
SCD1 IC50 = 261 nM
4. Merck Frosst
MK-8245
SCD IC50 = 3 nM
O
NH
O
CF3
N
N
N
N
N
N
N
N
F
O
N
N
5. Daiichi Sankyo
SCD IC50 = 2 nM
6. Pfizer
SCD IC50 = 11.7 nM
Figure 1. Recent published small molecule-based SCD1 inhibitors.
8
7
6
9
1
5'
6'
O
O
N
O
HN
5
NH
1'
N
N
H
4
3
3'
2'
O
7 mSCD1 IC50 = 6.4 µM
4,5-dihydro-3H-spiro[benzo[b][1,4]oxazepine-2,4'-piperidine]
Figure 2. Initial HTS hit compound 7.
HN
N
N
iii
i
ii
O
N
O
O
O
NH
N
O
O
O
8
9
10
R1
N
HN
N
O
v
iv
O
O
O
O
N
O
N
N
N
H
N
H
N
H
O
O
O
11
12
7, 13a-t
Scheme 1. Reagents and conditions: (i) benzaldehyde, NaBH(AcO)3, acetonitrile, 50 °C, 85%; (ii) HCl in dioxane (4 N), rt, 0.5 h, 95%; (iii) 2-acetamidoacetic acid, HATU, DIEA,
rt, 4 h, 70%; (iv) H2, Pd/C (10%) rt, 12 h, 100%; (v) R1CHO, NaBH(AcO)3, acetonitrile, 50 °C or R1Br, Cs2CO3.
partial eye closure.18–21 The severity and the time at which these
adverse effects were observed were directly related to the dose
being administered, thus suggesting that the toxicity is related to
the inhibitor’s mechanism of action.
To overcome some of the side effects observed in the previous
studies, one approach was to develop a SCD1 inhibitor with prefer-
ential distribution in liver tissue versus plasma and other tissues.
With higher exposure at the targeted tissue, a wider therapeutic
window was anticipated. Although there are several publications
reporting this approach,15,22 there are limited numbers of liver-
targeted SCD1 inhibitors available in the literature. Herein, we
report on a series of SCD1 inhibitors developed utilizing this

Y. Deng et al. / Bioorg. Med. Chem. Lett. 23 (2013) 791–796
793
Table 1
the isopentyl group of the progenitor 7 to smaller groups such as
isobutyl and propyl moieties resulted in loss of potency (13a and
13b). A direct linked phenyl group was also not tolerated (13c).
However, a benzyl group showed improved potency (11) compared
to 7. Further extension of the linkage to two carbons gives a similar
result as 13d and demonstrated comparable potency to 11. With
these results in hand we decided to focus on modifications to the
benzyl group.
Structure–activity relationships of SCD1 inhibitors at R1
R1
N
O
O
N
N
H
O
Compd
R1
SCD1 IC50 (lM)
The substitution on the benzyl group had profound effects on
the inhibitory potency of the compounds. At the 2-position of the
benzyl group, substituting hydrogen with fluoride (13e) resulted
in loss of potency, but chloride (13f) maintained similar potency.
While a methyl group (13g) retained similar potency, an ethyl
group (13h) improved the potency by threefold. Although the
methoxy group of 13i bears the same number of atoms as the ethyl
group, it reduced the potency by twofold, indicating that electronic
effects were also important to the binding of the inhibitor to the
enzyme. At the 3-position of the benzyl group replacement of the
hydrogen with a fluorine (13j) was not tolerated, however a chlo-
rine substituent (13k) improved potency. The electron rich meth-
oxy group showed no impact on potency (13l) but the electron
deficient trifluoromethoxy (13m) group improved the potency by
twofold. Subsequently, a more electron withdrawing trifluoro-
methyl group was introduced and the potency improved by
40-fold (13n). Substitution at the 4-position displayed different
SAR trends, for example devoid of activity. The impact of hydro-
phobicity at the 4-position was also evident; as changing from a
methyl group to a t-butyl group boosted the potency from 1.1 to
11
PhCH2
iso-Butyl
Propyl
1.2
13a
13b
13c
13d
13e
13f
13g
13h
13i
>10
>10
>10
1.6
>10
1.2
1.2
0.43
2.9
>10
0.83
1.8
0.68
0.032
0.46
>10
1.1
Ph
PhCH2CH2
2-FPhCH2
2-Cl PhCH2
2-MePhCH2
2-EtPhCH2
2-MeOPhCH2
3-FPhCH2
13j
13k
13l
3-Cl PhCH2
3-MeO PhCH2
3-F3COPhCH2
3-CF3 PhCH2
4-FPhCH2
13m
13n
13o
13p
13q
13r
13s
13t
4-ClPhCH2
4-MePhCH2
4-EthylPhCH2
4-iPrPhCH2CH2
4-tBuPhCH2
0.057
0.042
0.017
0.017 lM (13q, 13r, 13s and 13t).
With the identification of optimized motifs at the 5-position, we
shifted our efforts to the optimization of the 10-position. As shown
in Scheme 2, the optimal R1 was installed by reacting 8 with corre-
sponding aldehydes under reductive amination condition to afford
14, which was de-protected with TFA to give 15. Subsquetnly, the
compounds (16a–m) with various R2 group at 10-position were
synthesized by reacting 15 with corresponding carboxylic acids
and the bioactivities of this set of compounds are listed in Table
approach, and the in vitro and in vivo studies using a selection of
these compounds.
A high throughput screen was developed to measure the inhibi-
tion of SCD1 in vitro.23 Of the several series that were identified,
the benzo-fused spirocyclic oxazepine scaffold (Fig. 2) appeared
to have the most favorable combination of activity, preliminary
SAR, and freedom to operate. By mining our internal collection,
we were able to identify additional active compounds and generate
broader potency patterns.
2. Relative to 13q, substitution at the
a carbon was not tolerated
as both 16a and 16b lost their inhibitory activities. Replacing the
acetamide with a benzamide (16c) or nicotinamide (16e) resulted
in significant loss of potency, while the 2-furancarboxamide (16f)
restored potency. In comparing different amide substitents, 4-tert-
butylbenzyl showed better compatibility than the 3-trifluorometh-
ylbenzyl groups at the 5-position of the core, as 16c and 16f
exhibited better potency relative to the corresponding compounds
16d and 16g. Further optimization efforts resulted in little progress
towards additional potency improvement (16h–n).
Compound 7 and its derivatives 11, 13a–t were synthesized
following Scheme 1. The advanced intermediate Boc protected
4,5-dihydro-3H-spiro[1,5-benzoxazepine-2,40-piperidine]
8 was
prepared using literature procedures.24 The 5-nitrogen of com-
pound 8 was protected by a benzyl group by reacting it with benz-
aldehyde under reductive amination conditions to give compound
9. Removing the Boc group of 9 with TFA afforded 10 and coupling
it with acetyl glycine mediated by HATU in DMF gave 11 in good
yield. To enable diversification at the 5-position of the 4,5-dihydro-
3H-spiro[1,5-benzoxazepine-2,40-piperidine] core, the benzyl pro-
tecting group of 11 was removed using catalytic hydrogenation
to give compound 12. Its derivatives were then subsequently
synthesized under reductive amination, alkylation or arylation
conditions.
Examination of the structures of other reported inhibitors25 re-
vealed that heterocycles, particularly pyridazine, had been used to
link an amide to the core and shown activity enhancement. To
incorporate this motif into our series of inhibitors 6-bromo-N-(2-
cyclopropylethyl)-pyridazine-3-carboxamide was used to react
with the intermediate 15a and 15b under a thermal condition to
afford the corresponding compounds 17a and 17b (Scheme 3).
Table 1 summarizes the SAR at the 5-position of the 4,5-dihy-
dro-3H-spiro[1,5-benzoxazepine-2,40-piperidine] core. Changing
R1
N
R1
R1
HN
N
N
iii
i
ii
R2
O
O
N
O
O
N
N
O
NH
O
O
O
O
8
14a
16a-m
R1 = 4-tert-butylbenzyl
15a
R1 = 4-tert-butylbenzyl
14b R1 = 3-trifluoromethybenzyl
15b R1 = 3-trifluoromethybenzyl
Scheme 2. Reagents and conditions: (i) 4-tert-butylbenzaldehyde or 3-trifluoromethybenzaldyde, NaBH(AcO)3, acetonitrile, 50 °C, 85%; (ii) HCl in dioxane (4 N), rt, 0.5 h, 90%;
(iii) R2COOH, HATU, DIEA, rt, 4 h, 70%.

794
Y. Deng et al. / Bioorg. Med. Chem. Lett. 23 (2013) 791–796
Table 2
Table 3
Structure–activity relationships of SCD1 inhibitors at R2
Structure–activity relationships of SCD1 inhibitors at R3
R1
R1
N
N
O
N
O
O
N
R3
R2
Compd
R2
R1
SCD1 IC50
>10
(lM)
C0mpd
R1
R3
SCD1 IC50
0.04
(lM)
O
O
16a
4-tBuPhCH2
4-tBuPhCH2
N
H
17a
4-tBuPhCH2
N
N
HN
O
N
16b
>10
17b
17c
17d
3-CF3PhCH2
3-CF3PhCH2
3-CF3PhCH2
0.004
0.012
2.2
N
N
N
HN
O
O
H
N
16c
16d
4-tBuPhCH2
0.35
2.6
HN
O
O
O
H
N
3-CF3PhCH2
HN
O
N
H
N
17e
17f
3-CF3PhCH2
3-CF3PhCH2
0.93
0.13
N
16e
16f
16g
4-tBuPhCH2
4-tBuPhCH2
3-CF3PhCH2
1.5
S
HN
O
O
O
O
H
N
O
O
S
0.019
0.38
N
N
HN
O
17g
17h
17i
17j
3-CF3PhCH2
3-CF3PhCH2
3-CF3PhCH2
3-CF3PhCH2
0.01
4.7
H
N
N
N
N
N
NH2
O
OH
H
N
O
16h
16i
4-tBuPhCH2
4-tBuPhCH2
0.14
8.2
N
N
0.003
0.003
O
O
S
NH2
O
N
H
S
HN
O
NH2
N
N
17k
17l
4-tBuPhCH2
3-CF3PhCH2
3-CF3PhCH2
0.004
0.001
0.008
16j
4-tBuPhCH2
3-CF3PhCH2
0.18
2.45
S
S
HN
CN
O
O
NH2
N
16k
O
N
17m
16l
4-tBuPhCH2
5.9
S
OH
O
CN
16m
16n
4-tBuPhCH2
4-tBuPhCH2
0.44
3.3
N
We were pleased to find that both compounds showed good inhib-
itory potency and interestingly, 3-trifluoromethylbenzyl substitu-
ents at the 5-position of the core gave 10-fold better potency
compared to a 4-tert-butylbenzyl group (Table 3). The large
R1
N
R1
N
N
O
N
N
Br
i
N
N
+
O
O
HN
O
NH
HN
15a R1 = 4-tert-butylbenzyl
17a R1 = 4-tert-butylbenzyl
17b
15b
R1 = 3-trifluoromethybenzyl
R1 = 3-trifluoromethybenzyl
Scheme 3. Reagents and conditions: (i) DIEA, micro wave, 120 °C, 10 min, 65%

Y. Deng et al. / Bioorg. Med. Chem. Lett. 23 (2013) 791–796
795
Table 4
Table 5
Pharmacokinetic data of selected compounds
Concentration (ng/mL) of 17m and 2 in plasma collected at 4 h after dosing
Compd AUC (ng/
g h)
Cmax
(ng/g)
Plasma C6h
(ng/g)
Liver C6h
(ng/g)
C6h liver/
plasma
Dose
1 mg/kg
0.64
3 mg/kg
45
10 mg/kg
135
30 mg/kg
17m
2
1742
1775
13r
13s
13t
16e
17b
17c
17i
17j
17l
17m
2
1288
2608
3464
341
105
23
58
0
383
2308
1435
579
875
1095
169
209
45
45
0
105
495
599
19
100
210
18
0
0
0
0
<100
1655
2673
232
<10
<10
<10
0
1509
19,246
529
n/a
17
13
13
n/a
n/a
n/a
n/a
20
sure the in vivo SCD-1 activity, a desaturation index was calculated
from ratios of 16:1/16:0 or 18:1/18:0 fatty acids. Figure 3 shows
the lowering effect on the desaturation index following treatment
with 17m and 2. A dose-dependent desaturation index reduction
by 17m was observed, with a 21% reduction at 30 mg/kg, as mea-
sured by both 16:1/16:0 and 18:1/18:0. The control compound 2
showed 16% reduction in the desaturation index using 16:1/16:0
ratio and 22% reduction using 18:1/18:0 ratio when dosed at
30 mg/kg.
72
345
66
56
8.0
substitute on the amide was preferred as 17f and 17g were less
In the preliminary analysis, no abnormalities were observed in
the skin or eyes of the mice dosed at 30 mg/kg. The potential tox-
icity of 17m was assessed in male CD-1 mice administered single
daily doses of 0, 30, 100 or 300 mg/kg by oral gavage 17m and
300 mg/kg 2 for 2 weeks. All animals survived to terminal necropsy
with no effects on body weight or food consumption. Clinical signs
for mice administered 17m were limited to a few instances of lac-
rimation in the 300 mg/kg dose group. Clinical signs for mice
administered 2 consisted of peri-orbital swelling, alopecia, ocular
opacity, swelling of the lips and lacrimation in the 300 mg/kg dose
group.
There were no 17m or 2-related changes in hematology or ser-
um chemistry parameters. Small testes were observed in 3 of 4
mice in the 300 mg/kg 17m dose group at terminal necropsy. Mean
absolute and relative liver weights were higher in the 100 mg/kg
(19% and 20%, respectively) and 300 mg/kg (29% and 33%, respec-
tively) dose groups, compared to controls. Absolute and relative
peri-renal fat weights were lower than controls (not dose-related)
for the 100–300 mg/kg 17m dose groups and the 300 mg/kg 2 dose
group. Peri-renal fat weights for the 100 mg/kg 17m dose group
were comparable to the 300 mg/kg 2 dose group.
active. Since it is known that pyridazine amides can potentially
26
be subjected to extensive metabolism,
other heterocycles were
also explored. Replacing pyridazine with a pyridine group (17c) re-
duced potency slightly, while replacing it with a phenyl group
(17d) diminished the potency to above 1 lM. The thiazole deriva-
tives showed distinct SAR as the initial thiazole replacement gave a
compound with reduced potency (17e), but its smaller amide
derivatives exhibited more favorable inhibition of SCD1 (17i, 17j,
17k). Also, its cyano derivative 17l showed comparable potency
relative to its corresponding amide. As carboxylic acid derivatives
are potentially capable of distributing into the liver tissue prefer-
entially, several carboxylic acids were prepared. In contrast to
the low potency of pyridazine carboxylic acid 17h, the thiazole car-
boxylic acid derivative 17m demonstrated excellent potency.
Several potent compounds from different subseries were se-
lected to dose at 10 mg/kg in rats to evaluate their pharmacoki-
netic profiles. In addition to the drug exposure in plasma, drug
concentration in brain and liver was also recorded at the 6 h time
point; the data is summarized in Table 4. Among the compounds
evaluated, 17m displayed a desired pharmacokinetic profile. This
compound shows moderate exposure in plasma (AUC = 4.1
and has been found to target liver tissue preferentially. At 6 h post
dosing, the liver concentration was 21.7 g/g versus 0.46 g/g in
plasma, resulting in a liver/plasma ratio of 47. Due to its potent
enzymatic activity and superior PK properties, we decided to con-
duct further in vivo studies using 17m.
Compound 17m was evaluated in an acute efficacy study using
AKR mice, along with a control compound 2 (Fig. 3).13 Both com-
pounds were dosed 4 h before plasma sample collection. Table 5
lists the concentration of 17m and 2 in plasma samples. To mea-
lg/g h)
Compound 17m and 2 related microscopic findings were seen
in the harderian gland (atrophy, hyperplasia), skin (atrophy of
sebaceous gland), eyelid (atrophy of sebaceous gland), meibomian
gland (atrophy, squamous metaplasia) and eyes (corneal degener-
ation, inflammation). Atrophy of the harderian and meibomian
glands were observed in all dose groups. Changes in the eyes were
considered secondary to atrophy of the harderian glands. The
microscopic changes in the 300 mg/kg 17m dose group were
comparable to the findings for the 300 mg/kg 2 dose group. Dose-
related tubular atrophy of the testes was observed in the
l
l
(a)
(b)
16:1/16:0
18:1/18:0
0.15
2.5
***P<0.001 compare to "0" group
*P<0.05 compare to "0" group
2.0
*** ***
0.10
*
1.5
1.0
0.5
0.0
0.05
0.00
mg/kg 0
1
3
10
30
30
mg/kg 0
1
3
10
30
30
Cpd 17m
Cpd 2
Cpd 17m
Cpd 2
Figure 3. Plasma desaturation index lowering effect of SCD1 inhibitor 17m and 2 after 4 h treatment in 7 week old male AKR/J mice (n = 10/group) fed a 10% Kcal low fat diet
(Research Diets, D12450B). (a) Plasma desaturation index derives from fatty acids 16:1/16:0 and (b) plasma desaturation index derives from fatty acids 18:1/18:0.

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Y. Deng et al. / Bioorg. Med. Chem. Lett. 23 (2013) 791–796
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100–300 mg/kg groups. Minimal Leydig cell hyperplasia of the tes-
tes was seen only in the 300 mg/kg 17m dose group. There were no
test-article related testes findings for the 2 group.
Plasma-drug levels were determined at Day 13 following
2 weeks of daily dosing. Dose-related increases for both exposure
and Cmax were observed for 17m. Exposure [AUC(0–24 h)] for
17m at 30, 100 and 300 mg/kg was 114, 565 and 1520
respectively. Exposure [AUC (0–24 h)] for 2 at 300 mg/kg was
216 M h. Low levels of the glucuronide conjugate metabolite
lM h,
l
were observed for 17m in the 300 mg/kg samples.
Compound 17m administered orally for 2 weeks at doses of 30,
100 and 300 mg/kg caused stearoyl-CoA desaturase inhibitor class
effects similar to 2 (i.e., inhibition of fatty acid metabolism leading
to lesions of the eye and skin). Microscopic findings were compa-
rable between 17m and 2, despite greater dose-related exposure
to 17m. Further evaluation would be required to understand testic-
ular effects observed with 17m.
18. Nakamura, M. T.; Nara, T. Y. Annu. Rev. Nutr. 2004, 24, 345.
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Chem. 2000, 275, 30132.
In conclusion, we have identified a highly potent SCD1 inhibitor
17m with excellent pharmacokinetic profiles and a favorable tissue
distribution profile. As for the in vivo evaluation, 17m showed
moderate reduction of the desaturation index in the plasma after
a 4 h oral administration at 30 mg/kg. Although no notable abnor-
malities in the eyes or skin were observed at this dose, studies with
higher dosages over an extended period generated side effects re-
lated to target inhibition, suggesting further enhancement of the
selective distribution into the liver may be necessary to reduce side
effects and to develop this series of SCD1 inhibitors for the treat-
ment of metabolic disorders.
20. Li, C. S.; Belair, L.; Guay, J.; Murgasva, R.; Sturkenboom, W.; Ramtohul, Y. K.;
Zhang, L.; Huang, Z. Bioorg. Med. Chem. Lett. 2009, 19, 5214.
21. Leger, S.; Black, W. C.; Deschenes, D.; Dolman, S.; Falgueyret, J. P.; Gagnon, M.;
Guiral, S.; Huang, Z.; Guay, J.; Leblanc, Y.; Li, C. S.; Masse, F.; Oballa, R.; Zhang, L.
Bioorg. Med. Chem. Lett. 2010, 20, 499.
22. Lachance, N.; Gareau, Y.; Guiral, S.; Huang, Z.; Isabel, E.; Leclerc, J. P.; Leger, S.;
Martins, E.; Nadeau, C.; Oballa, R. M.; Ouellet, S. G.; Powell, D. A.; Ramtohul, Y.
K.; Tranmer, G. K.; Trinh, T.; Wang, H.; Zhang, L. Bioorg. Med. Chem. Lett. 2012,
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23. Leger, S.; Black, W. C.; Deschenes, D.; Dolman, S.; Falgueyret, J. P.; Gagnon, M.;
Guiral, S.; Huang, Z.; Guay, J.; Leblanc, Y.; Li, C. S.; Masse, F.; Oballa, R.; Zhang, L.
Bioorg. Med. Chem. Lett. 2010, 20, 499. detailed procedure as following: in
100
0.75
l
l
l of 100 mM Tris HCl, pH 7.3/2 mM NADH/20
Ci [9,10-3H-stearoyl] stearoyl-CoA per well. After a 15-min incubation at
of 20%
90-
volume from each well was transferred to a Millipore Multiscreen HTS 96-well
filtration plate, the wells of which contained 125 l of 10% activated charcoal
lM stearoyl-CoA containing
room temperature, plates were transferred to ice and 10
trichloroacetic acid was added to each well. After 5 min on ice,
ll
a
ll
References and notes
l
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to which vacuum had been previously applied to remove excess liquid and a
plastic seal then applied to the bottom. Plates were shaken 15 min and the
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contents were then filtered into a 96-well collection plate. A 50-
ll volume of
filtrate was counted in 150 l of MicroScint 40 in a TopCount scintillation
l
counter. Stock solutions of compounds, 10 mM in DMSO, were diluted in DMSO
for a final assay concentration of 2% DMSO. Percent inhibition was determined
as (total-sample)/(total-blank)(100); total activity was determined in the
presence of 2% DMSO and blank in the presence of 10–4 M concentration of a
standard inhibitor in 2% DMSO. The inhibition constant was determined with
the Prism non-linear, least-squares, curve-fitting program.
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