JD-5006 and JD-5037: Peripherally restricted (PR) cannabinoid-1 receptor blockers related to SLV-319 (Ibipinabant) as metabolic disorder therapeutics devoid of CNS liabilities

Article abstract of DOI:10.1016/j.bmcl.2012.08.004

Analogs of SLV-319 (Ibipinibant), a CB1 receptor inverse agonist, were synthesized with functionality intended to limit brain exposure while maintaining the receptor affinity and selectivity of the parent compound. Structure activity relationships of this series, and pharmacology of two lead compounds, 16 (JD-5006) and 23 (JD-5037) showing little brain presence as indicated by tissue distribution and receptor occupancy studies, are described. Effects with one of these compounds on plasma triglyceride levels, liver weight and enzymes, glucose tolerance and insulin sensitivity support the approach that blockade of peripheral CB₁ receptors is sufficient to produce many of the beneficial metabolic effects of globally active CB₁ blockers. Thus, PR CB₁ inverse agonists may indeed represent a safer alternative to highly brain-penetrant agents for the treatment of metabolic disorders, including diabetes, liver diseases, dyslipidemias, and obesity.

Full text of DOI:10.1016/j.bmcl.2012.08.004

Bioorganic & Medicinal Chemistry Letters 22 (2012) 6173–6180
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
JD-5006 and JD-5037: Peripherally restricted (PR) cannabinoid-1 receptor
blockers related to SLV-319 (Ibipinabant) as metabolic disorder
therapeutics devoid of CNS liabilities
⇑
Robert J. Chorvat , Jennifer Berbaum, Kristine Seriacki, John F. McElroy
Jenrin Discovery, 2515 Lori Lane North, Wilmington, DE 19810, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
Analogs of SLV-319 (Ibipinibant), a CB1 receptor inverse agonist, were synthesized with functionality
intended to limit brain exposure while maintaining the receptor affinity and selectivity of the parent
compound. Structure activity relationships of this series, and pharmacology of two lead compounds,
16 (JD-5006) and 23 (JD-5037) showing little brain presence as indicated by tissue distribution and
receptor occupancy studies, are described. Effects with one of these compounds on plasma triglyceride
levels, liver weight and enzymes, glucose tolerance and insulin sensitivity support the approach that
blockade of peripheral CB1 receptors is sufficient to produce many of the beneficial metabolic effects
of globally active CB1 blockers. Thus, PR CB1 inverse agonists may indeed represent a safer alternative
to highly brain-penetrant agents for the treatment of metabolic disorders, including diabetes, liver dis-
eases, dyslipidemias, and obesity.
Received 28 July 2012
Accepted 1 August 2012
Available online 20 August 2012
Keywords:
CB1 receptor inverse agonist
Metabolic disorders
Diabetes
Liver diseases
Dyslipidemias
Obesity
Ó 2012 Elsevier Ltd. All rights reserved.
JD-5006
JD-5037
SLV-319
Peripherally restricted cannabinoid-1
receptor blockers
Rimonabant
CB1 antagonist
The endocannabinoid system, comprised of the cannabinoid
receptors (CB1 and CB2) and their endogenous ligands (primarily
anandamide and 2-AG), plays a prominent role in the control of
food intake1 and energy metabolism.2 Stimulation of this system
triggers metabolic processes leading to weight gain, lipogenesis,
insulin resistance, dyslipidemias and impaired glucose homeosta-
sis. Consistent with these actions is the presence of CB1 receptors
widely expressed in brain, (cortex, hippocampus, amygdala, pitui-
tary and hypothalamus) as well as numerous peripheral organs
and tissues (thyroid, adrenals, reproductive organs, adipose tissue,
liver, kidney, muscle, pancreas, and gastrointestinal tract3,4) which
can mediate these pharmacological consequences. CB2 receptors
are mainly localized in blood and immune cells2 including macro-
phages, and regulate the inflammatory responses in various set-
tings.5 Evidence does exist, however, that these receptors may
also be present in the CNS.6
apart from their ability to control food intake through interaction
with CB1 brain receptors, an association supported by numerous
studies,2,7 a variety of inverse agonists have been shown to influ-
ence energy utilization through modulation of glucose metabolism,
as well as improving cardiometabolic risk factors associated with
obesity such as HDL-cholesterol and triglycerides.2 The effects of
these inverse agonists are most likely mediated through both cen-
tral and peripheral CB1 receptor interactions.3,4,8,9 Indeed, clinical
trials with Rimonabant, the first marketed inverse agonist, showed
improvement in glycemic control and lipid profile in type 2 dia-
betic patients (SERENADE),10 and loss of visceral, and hepatic fat
in abdominally obese patients (ADAGIO).11
The ability of CNS-penetrant CB1-antagonists/inverse agonists
to suppress food intake is generally associated with interactions
that target CB1 receptors in hypothalamus and mesolimbic regions
that control appetite.12 However, CB1 receptor blockers have equal
access in brain to non-targeted receptors that have little if any role
in appetite control, binding to which can often lead to unwanted
results.2–4,13 Indeed, the CB1 inverse agonists Rimonabant and
taranabant produce psychiatric and neurological side effects —
headache, irritability, insomnia, dizziness, anxiety, seizures,
depressed mood, and suicidality — which are dose-related, and
appear most pronounced at doses most efficacious in reducing
The ability of the CB1 endocannabinoid system to regulate food
intake and energy expenditure has prompted extensive work on
the utilization of blockers of these receptors as potential therapeu-
tic agents. As a result of these investigations, it has been found that
⇑
Corresponding author. Tel.: +1 484 356 3303; fax: +1 832 550 3120.
E-mail address: r.chorvat@jenrindiscovery.com (R.J. Chorvat).
0960-894X/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bmcl.2012.08.004

6174
R. J. Chorvat et al. / Bioorg. Med. Chem. Lett. 22 (2012) 6173–6180
weight (see Chart 1).14,15 The occurrence of therapeutic efficacy
(appetite suppression) and side effects over the same dose range
strongly suggested that both effects are mediated through concur-
rent interaction of CB1 receptors in both ‘targeted’ (hypothalamus)
and ‘non-targeted’ (frontal cortex, hippocampus and amygdale)
brain regions.16
characterization. Thus, this work was intended to identify potential
therapeutic agents with desirable biological properties mediated
through peripheral CB1 receptor blockade with an absence of the
untoward CNS side effects that have accompanied first generation,
brain-penetrant compounds currently terminated from further
clinical development or removed from the market.26
To overcome the unwanted CNS liabilities associated with
brain-penetrant CB1 antagonists/inverse agonists, we developed
a strategy to incorporate functionality that would eliminate or
diminish passive diffusion of compounds into the brain, or increase
the chances that these molecules would be substrates for efflux
transporters.17 One of these active transport systems, Pgp, has been
responsible for the limited brain exposure of a number of currently
marketed drugs that are substrates for this transport system.18 Uti-
lizing the structural feature information of low brain presence
agents, as well as in a reverse fashion, the conventional rules that
guide medicinal chemists in producing brain-penetrant com-
pounds,19 we investigated the compatibility of various structural
changes in different regions of the chemical lattice of the SLV-
319 (Ibipinibant) molecule on receptor affinity/selectivity, as well
the concomitant effects on lipophilicity, polar surface area (PSA),
and brain penetration potential. To support the strategy that a
CB1 receptor blocker with low brain exposure will have therapeu-
tic potential for alleviating cardiometabolic risk in obese patients,
it has recently been shown that a CB1 receptor neutral antagonist
(AM 6545), largely restricted to the periphery, did not affect behav-
ioral responses mediated by brain CB1 receptors.20 This agent did
cause weight-independent improvements in glucose homeostasis,
fatty liver, and plasma lipid profile in genetic or diet-induced obese
mice. Other reports of potential non-brain penetrant CB1 receptor
antagonists/inverse agonists have been reported, though the ab-
sence of brain presence with concomitant effects on metabolic
parameters is lacking.24
The initial target compounds, prepared to determine the effect
of incorporating H-bond donor/polar groups as substituents on
the phenylsulfonyl group, were synthesizd according to the se-
quence in Scheme 1. The diarylpyrazine A was prepared as previ-
ously described,27 and treatment with various sulfonylated
carbamic acid esters, which were obtained in a straightforward
manner from the corresponding aryl sulfonamides and methyl
chloroformate, provided the sulfonylated pyrazine-1-carboxamides
B. Conversion of B to the imidoyl chlorides C with PCl5 was followed
by methylamine treatment to afford the sulfonylated carboxami-
dines 1–9. Ester substituents on the phenyl ring produced the acids
(3 and 6) upon routine hydrolysis, and conventional amination
reactions gave the carboxamides and hydroxamic acids (4, 5 and
7). The nitro analog was reduced to the aniline using Fe-filings in
hydrochloric acid solution, and then converted to the acetamide
or carbamate (8 and 9).
Analogs with modifications on the amino methyl group of
SLV-319 could be conveniently prepared from the imidoyl chloride
C using a large variety of single or di-amino acid esters (see
Scheme 2). Further conversions of these esters of sulfonylated pyr-
azoline-1-carboxamidines to the amino carboxamide compounds,
were achieved through conventional amino acid/carboxamide
transformation methodology (compounds 10–44).
Compounds were initially evaluated for their binding affinity to
cannabinoid receptor sites by their ability to displace a [3H] ligand
from human recombinant CB1- and CB2-protein.28 Results from
these tests are shown in Tables 1–5. Compounds which showed
affinity P the 100 nM screening concentration were not evaluated
The calculated relative lipophilicity values of compounds were
used as an initial guide because of the role this property may have
in passive diffusion through the blood brain barrier as well as
retaining compounds within the brain,21 and overall PK and
safety.22 Polar surface area (PSA), defined as the surface sum over
all polar atoms, (usually oxygen and nitrogen), including attached
hydrogens, is also a common metric used for the estimation of pas-
sive molecular transport through membranes.23 This property has
been reported to be a basis for identifying various analogs of Rimo-
Cl
Cl
Cl
(b)
(a)
N
O
N
N
N
O
N
O
N
H
NH
Cl
N
S
O
O
nabant with a lowered propensity to pass the blood–brain-barrier.24
S
0
Molecules with a PSA of >140 ÅA squared are usually believed to
be poor at permeating cell membranes. For molecules to penetrate
C
X
B
A
X
(c)
the blood–brain-barrier (and thus interact with receptors in the
Cl
Cl
0
central nervous system), PSA is suggested to be less than 60 ÅA
squared.25 This property, along with cLogP, hydrogen bond
donors and molecular weight, all factors contributing to the likeli-
hood of a molecule penetrating the blood brain barrier and/or being
absorbed from the GI tract, were collectively used as guides for
identification of suitable analogs of SLV-319 for pharmacological
(d)
N
N
N
O
N
O
H3CHN
N
S
H3CHN
N
S
O
O
1, 2, 6
X'
X
3-5, 7-9
Cl
X' = CO2H, OCH2CO2H, CO2NH2, CONHOH,
OCH2CO2NH2 , NHCOCH3, NHCO2Et,
X = OCH3, CO2Et,
OCH2CO2Et, NO2
O
N
N
H
N
NH
N
Scheme 1. Reagents and conditions: (a) ArylSO2NHCO2CH3, toluene, reflux, 3–6 h,
30–95%; (b) PCl5, chlorobenzene, reflux, 2–4 h, 50–90%; (c) NH2Me.HCl, Et3N,
CH2Cl2, ice-bath to rt, 16–20 h, 30–70%; (d) X = CO2Et/X0 = CO2H: LiOH, H2O/
THF(1:3), 50%; X0 = CO2H/X0 = CONH2, (1) IBCF, NMM, CH2Cl2, (2) NH3/THF, 60%;
X0 = CO2H/X0 = CONHOH, (1) IBCF, NMM, CH2Cl2, (2) NH2OHꢀHCl, NMM, CH2Cl2, 40%;
X = OCH2CO2Et/OCH2CO2H: LiOH, H2O/THF(1:3), rt, 50%; X0 = OCH2CO2H/
X0 = OCH2CONH2: (1) IBCF, NMM, CH2Cl2, (2) NH3/THF, 30%; X = NO2:/X0 = NHC-
OCH3: (1) Fe/HCl, EtOH, H2O, reflux 1–2 h, 90%; (2) Ac2O, pyr, CH2Cl2, rt, 8 h, 90%;
X = NO2:/X0 = NHCO2Et: (1) Fe/HCl, EtOH, H2O, reflux 1–2 h, 90%; (2) ClCO2Et, pyr,
CH2Cl2, 0 °C to rt, 8 h, 90%.
H3C
O
N
N
H
N
NC
O
N
SO2
Cl
Cl
CF3
N
Cl
Cl
Cl
Rimonabant
Ibipinabant
Taranabant
Chart 1.

R. J. Chorvat et al. / Bioorg. Med. Chem. Lett. 22 (2012) 6173–6180
6175
Table 2
Cl
CB1 receptor binding affinities of compounds 10–15
Cl
(a)
C, X = Cl
N
N
O
N
H
N
S
m
A
RO2C
n
O
N
A
N
(d)
10, 12, 14
Cl
(b)
Cl
Z
N
H
N
Cl
O2S
N
N
A
H
N
Cl
N
RO2C
N
N
H
N
S
Compound
A
Z
CB1 IC50 (nM)
O
A'
O
N
H
N
m
HO2C
88%d
>1000
96%
n
10
11
H
H
CH3
CH3
H
CO2Me
O
O
D
S
A
CO2H
CO2Me
CO2H
O
Cl
12e
13e
14e
15e
Cl
11,13,15
>1000
(b)
(c)
(c)
d
CH2CHOHCO2Et
CH2CHOHCO2H
53%
H
>1000
Cl
d
e
Per cent inhibition at 100 nM.
(S)-Amino acid side chain.
Cl
N
N
O
(Table 7).29 Based on properties from these assays, two compounds
JD-5006 (16) and JD-5037 (23), were selected for further in vivo
characterization which included blood and brain level determina-
tions, brain CB1 receptor occupancy, and therapeutic efficacy
studies.
N
A
N
H
N
N
H
N
m
H2NOC
H2NOC
n
N
H
N
O
S
O
A'
O
A
S
O
Cl
16 - 35
Cl
36 - 44
Incorporation of a variety of more hydrophilic, hydrogen bond-
ing substituents in place of the chloro group at the 4-position of
the phenyl-sulfonyl ring showed diminished affinity for the CB1
receptor, especially with those groups with hydrogen-bond donor
properties (Table 1). Based on these early disappointing results,
we focused our attention on other regions in the molecule where
these types of functionalities might be compatible with high recep-
tor affinity.
Scheme 2. Reagents and conditions: (a) amino acid ester. HCl, Et3N, CH2Cl2, 0 °C to
rt, 20–90%; (b) LiOH, H2O/THF(1:3), 30–90%; (c) 1) IBCF, NMM, CH2Cl2, (2) NH3/THF,
60%; (d) diamino acid ester, Et3N, CH2Cl2, 0 °C to rt, 20–90%. m,n = 0,1.
Table 1
CB1 receptor binding affinities of compounds 1–9
Cl
Amino ester adducts at the central (N-methyl) region of the
SLV-319 molecule proved to be more promising since, in many
cases, these neutral compounds retained the high binding affinity
of the parent molecule, though the corresponding ionizable acids
possessed significantly diminished affinity for the CB1 receptor
(Table 2), a property shared by others series with this functional-
ity.24 Since these esters were expected to readily convert to the
low-affinity acids in vivo, they were of no interest as drug candi-
dates, and accurate IC50 values were not determined. They did,
however, demonstrate the compatibility of branched-chain pen-
dants at this position with high receptor affinity. Our attention
then turned to other non-ionizable functionality that would pro-
vide properties associated with decreased brain penetration due
to a reduction in passive diffusion, or participation with efflux
transporters.18,30 One of these functionalities was the carboxamido
group, an obvious analog of our amino acid adducts, and a group
indeed found in certain drugs, e. g., atenolol and labetolol, with
low brain presence.29 In addition, high-affinity carboxamide ana-
logs would also provide several other physicochemical properties
that should contribute to limited membrane permeability, for
example, lower lipophilicity, higher polar surface area,23 a greater
number of H-bond donors,31 and a concomitant increase in the
number of solvated water molecules (desolvation energy).32
Table 3 shows a number of these single amino carboxamido
adducts with a variety of side chains. Several of these racemic
N
N
H3C
N
H
N
O2S
X
a
Compound
X
CB1 IC50 (nM)
SLV-319c
Cl
22b
1
2
3
4
5
6
7
8
9
OMe
CO2Et
CO2H
CONH2
CONHOH
OCH2CO2H
OCH2CONH2
NHCOCH3
NHCO2Et
ꢁ100
ꢁ100
>5000
>5000
>5000
>5000
>5000
>1000
ꢁ300
a
Initial screening performed at two concentrations run in duplicate; values
P100 nM are estimated.
b
IC50 value determined from four point concn, curves in duplicate.
All compounds racemic unless designated otherwise.
c
(glycine, dimethyl-gly) or diastereomeric (natural L-amino acid
derived, unless indicated) molecules have binding affinities
comparable to, or higher than parent, SLV-319. Of note are those
high-affinity analogs with cLogPs significantly lower than the par-
ent structure (16, 17, 26, 28), and one, 23, with a cLogP comparable
further. Certain compounds with high affinity for the CB1-receptor,
and good selectivity over the CB2-receptor were also evaluated in
the kidney cell screen that assesses membrane permeability poten-
tial by the bi-directional passage across MDR1-MDCK mono-layers

6176
R. J. Chorvat et al. / Bioorg. Med. Chem. Lett. 22 (2012) 6173–6180
Table 3
CB1 receptor binding affinities and physicochemical properties of compounds 16–29
Cl
N
A
N
Z
N
H
N
O2S
Cl
a
Compounde
A
Z
cLogPf
TPSAg Ang2
CB1 IC50 (nM)
CB2 IC50 (nM)
SLV–319c
16
16a
16b
17
H
H
H
H
H
H
CH3
(CH3)2
CH2CONH2
CH2C6H5
CH(CH3)2
CH(CH3)2
CH(CH3)2
C(CH3)3
c-C4H6
(2S,3R)CHOHCH3
(2R,3S)CHOHCH3
CH2OH
H
H
5.88
4.64
4.64
4.64
4.79
5.28
5.13
5.52
3.70
6.80
6.01
6.01
6.01
6.55
5.58
4.59
4.59
4.27
4.25
74
117
117
117
117
117
117
117
—
22b
18
32
>1000
32
26
>5000
5000
CONH2
CONH2
CONH2
CH2CONH2
CH(CH3)CONH2
CONH2
CONH2
CONH2
CONH2
CONH2
CONH2
CONH2
CONH2
CONH2
CONH2
CONH2
>5000
>1000
>5000
>1000
>1000
>1000
>5000
>5000
>1000
>1000
—
>5000
>1000
>5000
>5000
>5000
>5000
18
19e
20
20
8.5
>100
61%d
2
1.5
>1000
2.0
8.3
7
21e
22e
23e
23ah
23bh
24e
25e
26e
27
—
117
117
117
117
117
138
138
138
—
>100
13
66
28e
29e
CONH2
CH2CHOHCONH2
a
b
c
Initial screening performed at two concentrations run in duplicate; values P100 nM are estimated.
IC50 value determined from four point concn, curves in duplicate.
All compounds racemic unless designated otherwise.
Per cent inhibition at 100 nM.
(S)-Amino acid side chain.
Crippen’s fragmentation: J. Chem. Inf. Comput. Sci., 1987, 27, 21.
Ertl, P., Rohde, B., Selzer, P., J. Med. Chem. 2000, 43, 3714.
Single diastereomer: 23a (S, ring, S, side-chain); 23b (R, ring, S, side-chain).
d
e
f
g
h
to SLV-319, but with a CB1 receptor affinity more than an order of
magnitude greater than SLV-319. The enantiomers of one racemic
compound, 16, were separated via chiral column chromatography,
and as expected the high receptor affinity resides with a single
reasonable predictor of brain permeability, as well as an indicator
of compounds that are actively participating in P-gp mediated ef-
flux processes.29 Generally, CNS penetrant drugs show absorptive
permeability coefficients in going from apical to basal layers (Papp
A–B) P 3.0 ꢂ 10ꢃ6 cm/s. Those drugs that have been found to have
low CNS penetration show a Papp A–B of <1.0 ꢂ 10ꢃ6 cm/s. Com-
pounds with intermediate values are likely to have low brain pres-
ence if the efflux rate Papp B–A exceeds the Papp A–B by more than
three-fold (efflux ratio P 3). Of the compounds evaluated in this
assay (Table 6), we early on selected 16 and 23 as agents with po-
tential for low brain exposure based on their Papp A–B coefficients
(1.8 and 1.1, respectively), as well as high efflux ratios (34 and 15,
respectively) and PSA values (both, 117 angstroms squared). They
were evaluated in vivo for plasma and brain exposure, brain CB1-
receptor occupancy, and therapeutic efficacy in pharmacological
assays that reflect potential therapy for the regulation of metabolic
dysfunction.
Racemic 16 was also characterized as an inverse agonist in for-
skolin-stimulated CHO cells over- expressing CB1-receptors by its
ability to affect cAMP as shown in Figure 1. Its IC50 of 46 nM was
comparable with that which we also determined for SLV-319,
IC50 = 139 nM and Rimonabant, IC50 = 51 nM. Establishing this
property with our lead compounds allowed us to characterize
non-brain penetrant versions of clinically effective compounds,35
and also determine if an inverse agonist would have equivalent
or better properties in certain pharmacological assays than those
of the neutral antagonist previously reported.20
compound (16a).33 Also in the case of 23, where
L-amino acid pen-
dant afforded a pair of diastereomers, the two components could
fortuitously be separated via silica gel column chromatography
and recrystallization to afford the potent diastereomer 23a which
was shown to have the same absolute configuration (S) of SLV-
319 at the chiral carbon of the pyrazoline ring.34
Table 4 shows analogs with other substituents on the phenyl-
sulfonyl group of forementioned adducts with CB1 receptor
affinities PSLV-319. In these cases, replacement of the 4-chloro-
substituent with a methoxyl or hydroxyl group, regardless of the
central amino acid pendant, diminished CB1 receptor binding
affinity. In this limited study, the optimal substituent on the
phenyl sulfonyl group of SLV-319 also seems best in the case of
the amino carboxamide adducts.
Table 5 shows the binding affinities for a number of di-amino
carboxamide adducts. Little difference in binding affinity was
indicated from the parent compound and the gly–gly, ala–gly,
and ala–ala carboxamides. The ala-ser 39 compound did show
higher binding affinity, an improvement also shared with the
thr-ser adduct 44. The high PSA values of these two analogs,
however, suggest general membrane permeability may be an issue.
Certain compounds were then evaluated in the MDR-MDCK cell
monolayer assay. This kidney cell line has been shown to be a

R. J. Chorvat et al. / Bioorg. Med. Chem. Lett. 22 (2012) 6173–6180
6177
Table 4
CB1 receptor binding affinities and physicochemical properties of compounds 30–35
Cl
N
R
N
H2NOC
N
H
N
O2S
X
Compound
R
X
cLogPd
TPSAeAng2
CB1 IC50 (nM)
CB2 IC50 (nM)
16
30
31
H
H
H
CH3
CH3
CH3
CH(CH3)2 (S,S)
CH(CH3)2
Cl
OCH3
OH
Cl
OCH3
OH
4.64
3.95
3.68
5.13
4.44
—
117
127
139
117
127
139
117
127
18b
ꢁ100a
>100
20
70
>500
0.5
>1000
>5000
.5000
>1000
>5000
>5000
>1000
>1000
32c
33c
34c
23a
35c
Cl
3-OCH3
6.01
5.33
4
a
b
c
Initial screening performed at two concentrations run in duplicate; values P100 nM are estimated.
IC50 value determined from four point concn, curves in duplicate.
(S)-Amino acid side chain.
Crippen’s fragmentation: J. Chem. Inf. Comput. Sci., 1987, 27, 21.
Ertl, P., Rohde, B., Selzer, P., J. Med. Chem. 2000, 43, 3714.
d
e
Table 5
CB1 receptor binding affinities and physicochemical properties of compounds 36–44
Cl
N
H
R
N
H2NOC
N
N
H
N
O
Z
O2S
X
Compound
X
Rc
Zc
cLogPd
TPSAeAng2
CB1 IC50 (nM)
CB2 IC50 (nM)
36
Cl
Cl
Cl
Cl
OMe
Cl
OMe
Cl
H
CH3
CH3
CH3
H
H
3.49
3.98
4.47
3.48
3.62
4.87
4.18
5.36
3.08
146
148
—
167
—
—
—
—
187
25b
10
27
>5000
>1000
>5000
>5000
>5000
>1000
>5000
>5000
>1000
37c
38c
39c
40c
41c
42c
43c
44c
CH3
CH2OH
CH2OH
H
8
CH3
>100a
>100
>100
ꢁ100
7
CH(CH3)2
CH(CH3)2
CH(CH3)2
CH(CH3)OH
H
CH3
CH2OH
Cl
a
b
c
Initial screening performed at two concentrations run in duplicate; values P100 nM are estimated.
IC50 value determined from four point concn, curves in duplicate.
(S)-Amino acid side chain.
Crippen’s fragmentation: J. Chem. Inf. Comput. Sci., 1987, 27, 21.
Ertl, P., Rohde, B., Selzer, P., J. Med. Chem. 2000, 43, 3714.
d
e
Plasma and brain levels of 16a,36 2337 and SLV-319 in chow fed
at a lower (20 mg/kg) dose. As has been previously reported, Rimo-
nabant shows greater brain pentrance relative to SLV-319.39
To confirm negligible if any brain presence of these compounds,
they were also evaluated for CB1 receptor occupancy in hippocam-
pal and cerebellular regions of mice after administering doses of 3
or 30 mg/kg, PO, over a 3 day period with tissues collected 1 h after
the last dose. In this study, shown in Table 8, SLV-319 and Rimona-
bant showed total displacement of [3H] SR-141716A at 30 mg/kg in
both brain regions, whereas, 16a, and 23a showed little displace-
ment of radio ligand in these two brain sections under these
conditions at this dose. The variability of this assay (5 animals
mice were determined after oral administration of 100 mg/kg
doses of compound over a 3 day period.38 As shown in Table 7, high
plasma levels of administered compound were detected when
analysis was performed 1 h after administration of the last dose.
While the plasma levels of 16 are even greater than SLV-319 at this
dose, the total brain levels are only a fraction of that observed for
the parent compound. Similarly with 23, plasma levels also ap-
proach that of the parent at this high dose, but brain level remains
below the level of detection (LOD) in this assay. Tissue distribution
levels of Rimonabant are also included, though it was administered

6178
R. J. Chorvat et al. / Bioorg. Med. Chem. Lett. 22 (2012) 6173–6180
Table 6
MDR-MDCK mono layer cell transport of selected compounds.
c
Compound
R
Papp(ꢂ 10ꢃ6 cm/s)
Efflux ratio
A–B
9.45
1.80
0.20
0.88
B–A
10.0
60.5
22.3
SLV319a
16
36
CH3
CH2CONH2
CH2CONHCH2CONH2
CH2CH2CONH2
ꢁ1
34
112
66
17
58,0
26b
24b
19b
23b
38b
CHCHOHCH3CONH2
CH[C(CH3)3]CONH2
CHCH3CONH2
CH[CH(CH3)2]CONH2
CHCH3CONHCHCH3CONH2
<0.9
0.7
2.44
1.08
0.3
18.6
<0.1
9.25
16.6
nt
>20
—
3.8
15
—
a
b
c
All compounds racemic unless designated otherwise.
(S)-Amino acid side chain.
Ref. 29.
Table 7
100 mg/kg of SLV-319, 16a and 23 and 20 mg/kg of Rimonabant PO for 3 consecutive days in Chow-fed Mice
Compound
PO dose (mg/kg)
Avg plasma(ng/mL)
Avg brain(ng/gm)
% Brain versus plasma
SLV-319
16a
23
100
100
100
20
5132
16693
3849
2083
685
<LOD
1075
41
4
<1
89
Rimonabant
1203
per dose) accounts for the displacement seen at the 3 mg/kg dose
in the hippocampal regions of the brain.
administered PO 20 mg/kg of test compound for seven days then
challenged with a 2 gm/kg of body-weight dose of glucose. The
ability of these animals to tolerate this glucose challenge was sig-
nificantly improved by the more rapid elimination of glucose from
the animals treated with both 16 and Rimonabant (Fig. 5). In addi-
tion, in this same test group of animals both compounds enhanced
insulin sensitity as indicated by the diminshed levels of insulin that
were present during the glucose tolerance testing (Fig. 6).
In summary, we have prepared novel SLV-319 analogs with
functionality that can diminish brain exposure while maintaining
high potency and selectivity for the CB1 receptor. Based on physi-
cochemical properties, we chose to study two analogs to establish
whether a compound with little or no brain exposure would mimic
the pharmacological profile of known brain penetrant CB1 inverse
agonists without the potential to cause neuropsychiatric side ef-
fects. Tissue concentration and CB1 receptor occupancy studies
showed minimal brain levels of 16 and 2340 when compared to
the known brain penetrant compounds. However, in spite of this
lack of direct brain receptor interaction, 16 was shown to normal-
ize triglyceride levels, liver mass and ALT as well demonstrating a
beneficial effect on glycemic control. Our results support the
hypothesis that blockade of peripheral CB1 receptors may be
We further evaluated compound 16 in vivo to determine effi-
cacy on a number of cardiometabolic parameters. Figure 2 shows
the effects of SLV-319 and 16 on triglyceride levels after dosing or-
ally at 3, 10 and 30 mg/kg for 21 days in DIO mice. In this assay
both compounds showed maximal efficacy in normalizing triglyc-
eride levels to vehicle controls at the lowest dose tested. Parallel-
ing this effect was a concomitant normalization in terminal liver
weights with a maximal effect again achieved at the lowest dose
tested as shown in Figure 3. The salutary effects on liver were also
indicated by normalization of the terminal ALT (alanine amino
transferase) levels after this dosing period as indicated in Figure 4.
ALT is an enzyme that often reflects abnormal liver function due to
liver cell damage, or conditions predisposing the liver toward this
state. In all figures, p-values for the various doses are indicated in
each bar or column.
Rimonabant and 16 were also evaluated in a model of diabetes
where mice, maintained on a high fat diet for 14 weeks, were
5006 cAMP Inverse Functional
110
90
Table 8
CB1 Receptor Occupancy in Mouse Brain of Rimonbant, SLV-319, 16a and 23a
Compound
Brain region
% Occupancy
30 mg/kg
70
3 mg/kg
Rimonabant
SLV-319
16a
Hippocampus
Hippocampus
Hippocampus
Hippocampus
Cerebellum
Cerebellum
Cerebellum
Cerebellum
10a
15
10a
10a
12
15
0
100
100
3.0
0
87
102
0
50
23a
30
Rimonabant
SLV-319
16a
10
23a
0
0
-10
Chow fed mice were administered compounds once daily at 3 or 30 mg/kg PO for 3
consecutive days, and euthanized one hour after the last dose. Thirty minutes
before euthanization, animals were given an injection of [3H]SR141716A (Amer-
1x10-10
1x10-8
1x10-6
CONC (M)
sham Biosciences; 2 l
Ci in 0.1 ml water) via the lateral tail vein.40
a
Indicative of the variability of this assay with only 5 animals per dose.
Figure 1. Inverse agonist activity of 16, Rimonabant and SLV-319.

R. J. Chorvat et al. / Bioorg. Med. Chem. Lett. 22 (2012) 6173–6180
6179
Figure 5. Effects of Rimonabant and 16 on glucose tolerance.
Figure 2. Terminal fasting triglyceride levels after oral PO dosing of SLV-319 and 16
for 21 consecutive days at 3, 10 and 30 mg/kg in DIO mice.
Figure 6. Effects of Rimonabant and 16 on insulin sensitivity.
ment of metabolic disorders, including diabetes, dyslipidemias,
liver diseases, and obesity.41
Acknowledgments
Figure 3. Terminal liver weights after after PO dosing of SLV-319 and 16 for 21
consecutive days at 3, 10 and 30 mg/kg in DIO mice.
We wish to acknowledge and thank the chemists at SAR Life
Sciences, Hangzhou, China, for compound synthesis.
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.bmcl.2012.
08.004.
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