Imidazopyridazinones as novel PDE7 inhibitors: SAR and in vivo studies in Parkinson's disease model

Article abstract of DOI:10.1016/j.bmcl.2012.07.077

The synthesis and structure-activity relationship studies of a series of compounds from imidazopyridazinone scaffold as PDE7 inhibitors are disclosed. Potent analogs such as compounds 7 (31 nM), 8 (27 nM), and 9 (12 nM) were identified. The PDE selectivit

Full text of DOI:10.1016/j.bmcl.2012.07.077

Bioorganic & Medicinal Chemistry Letters 22 (2012) 6286–6291
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Imidazopyridazinones as novel PDE7 inhibitors: SAR and in vivo studies
in Parkinson’s disease model
Abhisek Banerjee, Sandip Patil, Mahesh Y. Pawar, Srinivas Gullapalli, Praveen K. Gupta, Maulik N. Gandhi,
Deepak K. Bhateja, Malini Bajpai, Ramachandra Rao Sangana, Girish S. Gudi, Neelima Khairatkar-Joshi,
⇑
Laxmikant A. Gharat
Glenmark Pharmaceuticals Limited, Navi Mumbai, Maharashtra 400709, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 4 May 2012
Revised 2 July 2012
Accepted 24 July 2012
Available online 8 August 2012
The synthesis and structure-activity relationship studies of a series of compounds from imidazopyridaz-
inone scaffold as PDE7 inhibitors are disclosed. Potent analogs such as compounds 7 (31 nM), 8 (27 nM),
and 9 (12 nM) were identified. The PDE selectivity and pharmacokinetic profile of compounds 7, 8 and 9
are also disclosed. The adequate CNS penetration of compound 7 in mice allowed it to be tested in the
MPTP induced PD model and haloperidol induced catalepsy model to probe the differential pharmacology
of PDE7 in the striatal pathway.
Keywords:
PDE7
Ó 2012 Elsevier Ltd. All rights reserved.
Imidazopyridazinone
CNS penetration
Parkinson’s disease
MPTP
Haloperidol
Phosphodiesterase 7 (PDE7) an enzyme that selectively hydro-
lyzes cAMP, has been extensively targeted for the treatment of a
host of immunological and autoimmune conditions.1 Recently,
interest with PDE7 inhibitors has emerged in the context of Parkin-
son’s disease (PD)2, considering the expression of PDE7A and 7B,
the two isoenzymes of PDE7, in rodent and human brain.1 The
interest was further spurred by the findings that showed PDE7
inhibition can protect dopaminergic neurons against different in-
sults in the lipopolysaccharide rat model of PD.3,4 Furthermore,
the dopamine receptors D1 and D2 signaling5 has been proposed
to be modulated by PDE7 via cAMP levels. It has been shown that
PDE7 inhibitor alone or in combination with Levodopa (l-dopa) in-
creased neuronal activation and restored paw stride length in
MPTP treated mice model.6 However, sub-optimal potency doses7
were found to produce maximal efficacy and higher doses were re-
ported to be sub-efficacious.6 Interestingly, this observation can be
correlated with the impact of PDE inhibition in the D1 receptor
dependent ‘direct’ and D2 receptor dependent ‘indirect’ striatal
pathways. Considering this background, our initial goal was to
identify potent, selective, CNS-penetrating PDE7 inhibitors to eval-
uate the potential of PDE7 inhibition as a novel target in the PD
therapy.
We have disclosed the structure-activity relationship of iso-
thiazole and isoxazole fused pyrimidones (II) inspired from (I) as
PDE7 inhibitors with adequate CNS penetration.8 Additionally,
we were also keen on exploring structurally diverse CNS penetrat-
ing PDE7 inhibitors. Based on previous PDE7 SAR studies,8,9 we
hypothesized that an imidazopyridazinone scaffold (III) (Fig. 1)
would allow us to explore alternate trajectory for essential/pre-
ferred substituents. In this communication we describe the synthe-
sis, SAR, PDE selectivity, and pharmacokinetic profile of a series of
compounds from this scaffold. Moreover, we also wish to report
our findings of the in vivo experiments in the MPTP treated mice
model of PD and in the haloperidol induced catalepsy model.
Synthetic access to imidazopyridazinone (III) where R1 = H, has
been previously reported by Gres’ko et. al.10 We realized that we
could access the desired PDE7 SAR by alkylation of compound 3
with various alkyl bromides to provide 4, at which point the syn-
thesis could proceed to (III) (analogs 16–19 and 21) in a manner
similar to that previously described (Scheme 1).10 In the case
where R2 = –NO2, reduction to the amine (7)11 could be effected
with iron and ammonium chloride in methanol. Subsequent reac-
tion of the amine (7) with phenylchloroformate, followed by treat-
ment with methylamine hydrochloride provided 22. In the case
where R2 = –CN, the nitrile was readily hydrolyzed to the acid,
esterified, reacted with hydrazine hydrate then followed by treat-
ment with triphosgene to form the oxadiazolone analog 23. In the
case where R2 = methylacrylate, compound 24 could be readily
⇑
Corresponding author. Tel.: +91 022 6772 0000x3208.
E-mail address: laxmikant_gharat@glenmarkpharma.com (L.A. Gharat).
0960-894X/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bmcl.2012.07.077

A. Banerjee et al. / Bioorg. Med. Chem. Lett. 22 (2012) 6286–6291
6287
R2
ethylsulfonium iodide and sodium hydride provided the
cyclopropyl ester intermediate. Hydrolysis of the ester followed
by coupling with ammonium chloride provided 26. The removal
of the protecting groups (Boc or THP) in III with a saturated solu-
tion of HCl in ethyl acetate provided the compounds 8–15 and
27–31. The synthesis of compound 20 was accomplished upon
acylation of compound 9 using acyl chloride.
The target compounds were tested for their inhibitory activity
at the cloned human recombinant PDE7A, PDE7B and other PDE
isozymes following a two step radiometric assay using 3H-cAMP
as the radioligand.12
NH2
N
X
N
N
O
NH R3
N
N
R1
NH
O
O
(II)
X: S, O
(I)
PDE7A IC50: 1.30 nM
R1: cyclohexyl, aryl
R2: various groups
R3: OMe, OEt, F
We were gratified to find that our hypothesis that the imidazo-
pyridazinone scaffold could provide potent PDE7 inhibitors was
correct. In general, the potency of the imidazopyridazinone com-
pounds followed the SAR we had previously observed with our iso-
thiazole and isoxazole fused pyrimidone scaffolds (II) (Table 1).8
Our first compound prepared in this series (7) was a potent inhib-
itor of PDE7 (31 nM) which was about twofold less potent than
(IIa). Per our expectation, the aminopiperidine derivative (8) was
equipotent in comparison with compound 7 and an increase in ring
size (9) resulted twofold increase in potency. However, a surprising
fourfold loss in potency was observed with the piperazine deriva-
tive (10). The isomeric aminopyrrolidines (11 and 12), aminoaziti-
dine (13), pyrrolidine ether (14) and the pyrazole (15) derivatives
were less potent in direct comparison with 9. At the R2 position
of III the use of cyclic amines with a hydroxy substituent as H-bond
O
N
N
N
R2
R1
N
H
O
(III)
Figure 1. PDE7 inhibitors.
prepared by hydrolysis of the ester followed by coupling with
ammonium chloride. Hydrogenation of 24 provided 25. Alterna-
tively, in the case where R2 = methylacrylate, reaction with trim-
NH2
NO2
NH2
NO2
NH2
N
N
c
d
O
O
N
N
b
a
N
HN
N
HN
R1
NH2
R1
O
OH
O
O
O
(5)
(4)
(3)
2
(1)
( )
R1: cHex, Bn, cPent, cHept,
2-ethylhexyl, N-methylpiperidinyl
CHO
O
O
(6)
R2
N
N
e
R2
N
R1
N
H
(III)
O
O
O
N
X
N
THP
,
R2: -NO2, -CN,
f
,
,
m
n
N
O
NBoc
m: 1-2; n: 1-3;
g
R2: -NH2
(7)
R2: -NHCONHMe
X: -N(Boc)-, -CH(NHBoc)-, -CH(OH)- (16-19), -CONH- (21)
(22)
m
O
h
O
k
O
N
(
m
X ,
n
N
H
23
)
,
NH
O
N
j
NH
14
N
NH2
15
)
(
(
)
m: 1-2; n: 1-3;
(24)
O
X: -NH- (9,10), -CH(NH2)- (8, 11-13, 27-31),
O
NH2
NH2
n
l
(25)
X: -NAc-
(20)
26
(
)
Scheme 1. Reagents and conditions: (a) (i) NH2–NH2ÁH2O, EtOH, reflux, 3 h; (ii) Br2, AcOH, 90 °C, 6 h; (b) (i) NH2–NH2ÁH2O,160 °C, 16 h; (ii) conc. HNO3, conc. H2SO4, 0 °C to rt,
3 h; (iii) conc. H2SO4, 60 °C, 5 h; (c) R1-Br, K2CO3, DMF, 110 °C, 16 h; (d) Fe, AcOH, reflux, 12 h; (e) aldehyde (6)8, sulfur, xylene, 160 °C, 2 h; (f) Fe, NH4CI, MeOH, rt, 2 h; (g) (i)
PhOCOCI, Et3N, THF, rt, 1 h; (ii) MeNH2ÁHCI, DMSO, 50 °C, 5 h; (h) (i) NaOH, MeOH, rt, 18 h; (ii) conc. H2SO4, EtOH, reflux, 4 h; (iii) NH2–NH2ÁH2O, EtOH, reflux, 3 h; (iv)
triphosgene, THF, reflux, 2 h; (j) (i) LiOH, MeOH–THF–H2O, rt, 10 h; (ii) NH4CI, PyBOP, DIPEA, DMF, rt, 12 h; (k) Pd/C, H2, MeOH, 40 psi, 2 h; (I) (i) trimethylsulphonium iodide,
NaH, DMSO, rt, 18 h; (ii) LiOH, THF–MeOH–H2O, rt, 2 h; (iii) NH4CI, PyBOP, DIPEA, DMF, rt, 12 h; (m) HCl in EtOAc, rt, 4 h; (n) AcCI, Et3N, CH2CI2, rt, 1 h.

6288
A. Banerjee et al. / Bioorg. Med. Chem. Lett. 22 (2012) 6286–6291
Table 1
donor were well tolerated (16–19) and the azepinol derivative (19)
SAR of the R2 position of Imidazopyridazinone
provided a potent PDE7 inhibitor. The use of H-bond acceptor was
also tolerated as evident from the activity of the compound 20.
Since both H-bond donors and acceptors were well tolerated, we
prepared examples which were capable of providing both interac-
tions (21–26) and observed that both piperazinone (21) and urea
(22) were the most potent among the analogs prepared. However,
the oxadiazolone derivative (23) was fourfold less potent than 21.
Among the acyclic amide derivatives (24–26), the cyclopropyl
amide 26 was most potent. Therefore, the H-bond donor and/or
acceptor groups were able to provide potent PDE7 inhibitors in
the imidazopyridazinone scaffold.
Example
PDE7A IC50 (nM) SDa
NH2
N
O
S
N
IIa
III
14 4.5
NH
O
O
N
N
N
Based on our prior experience in designing PDE7 inhibitors we
conducted a limited SAR effort at the R1 position of III (Table 2).
As expected the cycloalkyl analogs (8, 27, 28) were the most potent
among the analogs prepared.
R2
N
H
O
R2
The PDE selectivity profile of representative compounds 7, 8
and 9 presented in Table 3 suggests that the compounds were
non-selective within PDE7 isoforms. The compounds were inactive
against other PDE isoforms except PDE4 where the compounds
7
8
–NH2
31 4.09
27 7.64
N
NH2
N
NH
NH
NH2
9
12 1.75
have shown >50% inhibition at 10
fore, the PDE4 IC50’s of compounds 7 and 9 were determined
(6.55 M and 2.9 M, respectively) and it was confirmed that the
lM of test concentration. There-
10
11
N
N
104 25.67
80 14.09
l
l
compounds were having reasonable selectivity against this en-
zyme in comparison with PDE7A (>200 fold) and PDE7B (>150
fold).
N
Next, we attempted to identify a tool compound with reason-
able brain penetration, suitable for the MPTP (1-methyl-4-phe-
nyl-1,2,3,6-tetrahydropyridine) treated mice model of PD.
Therefore, we further evaluated the pharmacokinetic profile of
compounds 7, 8 and 9 (Table 4). The compounds were relatively
less stable in mouse liver microsomes and more importantly only
compound 7 had shown reasonable brain concentrations upon
10 mg/kg i.p. administration in mice. Thus we decided to use com-
pound 7 as our tool molecule for in vivo evaluation. The mouse
12
13
77 10.34
73 7.59
NH2
NH2
N
O
14
55 10.87
N
H
NH
N
15
16
45 10.73
53 14.03
N
N
OH
17
18
19
71 22.99
81 19.07
33 7.17
Table 2
OH
OH
SAR of the R1 position of imidazopyridazinone
N
N
O
N
N
OH
N
NH2
N
R1
N
H
N
N
O
NAc
20
21
32 7.17
18 2.81
Example R1
PDE7A % Inh. @
PDE7A IC50 (nM)
SDb
1 l
Ma
NH
O
8
96%
89%
27 7.64
ND
H
N
H
N
22
23
24
25
24 6.74
27
O
O
O
28
29
92%
75 15.23
68 17.98
89 15.40
93 12.67
NH
O
N
7%
ND
ND
ND
N
NH2
O
30
31
6%
NH2
O
13%
26
3
10.98
NH2
ND: Not determined.
a
% Inhibition values are means of two experiments.
IC50 values are means of three experiments.
a
b
IC50 values are means of three experiments.

A. Banerjee et al. / Bioorg. Med. Chem. Lett. 22 (2012) 6286–6291
6289
Table 3
PDE selectivity profile
Compound
IC50 (nM)
PDE7A SDa
31 4.09
27 7.64
12 1.75
% Inhibition at 10
PDE 5A
l
Mc
PDE7Bb
PDE 1A
PDE 2A
PDE 3A
PDE 4D
PDE 8A1
PDE 9A2
PDE 10A
PDE 11A
7
8
9
43
11
19
37
16
33
29
40
28
6
2
4
86d
81
3
32
3
0
6
19
9
9
12
23
40
2
10
44
24
90e
a
b
c
IC50 values are means of three experiments.
IC50 values are means of two experiments.
% Inhibition values are means of two experiments.
d
e
IC50 6.55
IC50 2.9
l
M.
l
M.
Table 4
Liver microsomal stability and pharmacokinetic profile of compounds 7, 8 and 9
Compound
Metabolic stability (% remaining)a
Male C57 Mouse PK (10 mg/kg i.p.)b
HLM
RLM
MLM
Cbrain (ng/g)c
Cplasma (ng/mL)c
Cbrain/ Cplasma
Cmax (ng/mL)
AUC (ng.h/mL)
Tmax (h)
7
8
9
43
100
90
68
100
40
4
44
37
1138
46
39
699
451
446
1.69
0.1
0.09
1478
902
570
792
2300
1374
0.25
4
0.25
a
b
C
Percentage of test compound remaining after 60 min incubation with liver microsomes (human, rat and mouse) at 37 °C.
i.p. formulation: 2.5 L/mL Tween 80, 0.5% Methyl Cellulose suspension.
Brain and plasma samples were collected 30 mins post i.p. dose.
l
PDE7A IC50 (63 nM)12 and C57 mouse brain homogenate binding13
(99.8% bound; 0.2% free) of compound 7 were determined. The
pharmacokinetic parameters of compound 7 at various doses were
also determined and the results are summarized in Table 5. Based
on these results it was evident that at the 10 mg/kg dose upon i.p.
administration, the free brain concentration achieved was 10-fold
lower than the mouse PDE7A IC50 (Table 5). However, free brain
concentration achieved at the 30 and 100 mg/kg doses were com-
parable and many fold higher than the mouse PDE7A IC50, respec-
tively (Table 5).
The in vivo efficacy of compound 7 was evaluated in the acute
mice models of MPTP induced PD14 and a dopamine D2 receptor
antagonist, haloperidol induced catalepsy (HIC).15 The compound
7 was studied over a wide range of doses (1, 3, 10 and 30 mg/kg,
i.p.) on rearing behavior in MPTP induced PD in male C57BL/6 mice.
Compound 7 produced a statistically insignificant dose dependent
increase in rearing behavior at sub-optimal doses (1, 3 and 10 mg/
kg, i.p.) and did not produce any efficacy at the highest dose
(30 mg/kg, i.p.) tested in the MPTP treated mice (Fig. 2). However,
the standard reference treatment l-dopa/benserazide (BSZ) pro-
duced significant effect on vertical rearing behavior in these mice.
In contrast to previous literature evidence,6 the PDE7 inhibitor
(compound 7) per se did not produce significant efficacy on rearing
behavior in MPTP treated mice. However, it may still be possible
for PDE7 inhibitors to potentiate the beneficial effect of l-dopa by
synergizing with the dopamine D1 receptor mediated cAMP signal-
ing in the ‘striatal direct pathway’.
Sham
Vehicle
350
300
250
200
150
100
50
*
L-Dopa/BSZ 15/12.5 mg/kg, s.c./i.p.
Compound 7 1 mg/kg, i.p.
Compound 7 3 mg/kg, i.p.
Compound 7 10 mg/kg, i.p.
Compound 7 30 mg/kg, i.p.
0
-50
-100
-150
MPTP
Figure 2. Effect of compound 7 on rearing in MPTP treated male C57BL/6 mice. ⁄p
<0.05 versus vehicle by one-way Anova/Tukey’s test.
In order to understand the possible reason for efficacy at sub-
optimal doses and reduced/lack of efficacy at higher doses as ob-
served from present and previous6 findings, we further probed
the effect of compound 7 alone and in combination with dopamine
D2 receptor antagonist, haloperidol in the catalepsy bar test. Dopa-
mine D2 receptors of the ‘striatal indirect pathway’ coupled to
inhibitory G proteins results in an increase of cAMP levels upon
blockade by D2 antagonist such as haloperidol, an antipsychotic
known for its catalepsy like extra pyramidal (EPS) side effects.16
Compound 7 produced a degree of catalepsy in mice at a dose of
30 mg/kg (i.p.) but did not show any effect in this model at doses
Table 5
Pharmacokinetic parameters and brain concentration profile of compound 7
Dosea
Cmax (ng/mL)
AUC (ng.h/mL)
Tmax (h)
Cplasma (ng/mL)b
Cbrain (ng/g)b
Cbrain/ Cplasma
Estimated Free brain conc.c
(ng/g)
(nM)
10 mg/kg
30 mg/kg
100 mg/kg
1478
6353
44185
792
5019
168407
0.25
0.25
0.5
699
4680
44185
1138
16048
134745
1.69
3.43
3.05
2
32
270
6
91
763
a
b
c
Male C57 mice were used for the experiments upon i.p. administration; i.p. formulation: 2.5
Brain and plasma samples were collected 30 mins post i.p. dose.
Free brain concentrations were estimated using the mouse brain homogenate binding (99.8% bound; 0.2% free).
lL/mL Tween 80, 0.5% Methyl Cellulose suspension.

6290
A. Banerjee et al. / Bioorg. Med. Chem. Lett. 22 (2012) 6286–6291
300
250
200
150
100
50
***
***
***
***
Vehicle (saline)
Halo 0.1 mg/kg, s.c.
Halo 0.3 mg/kg, s.c.
Halo 0.9 mg/kg, s.c.
Vehicle (compound 7)
Compound 7 1 mg/kg, i.p.
Compound 7 3 mg/kg, i.p.
Compound 7 10 mg/kg, i.p.
Compound 7 30 mg/kg, i.p
###
*
##
0
Haloperidol
Compound 7
Haloperidol
Compound 7
1.0
0.5
Time post treatment (h)
Figure 3. Effect of haloperidol and compound 7 on catalepsy bar test in male C57BL/6 mice. ⁄p <0.05, ⁄⁄⁄p <0.001 versus Naive by one-way Anova/Tukey’s test.
Veh + Veh
In conclusion, we have reported the synthesis and SAR evalua-
tion of imidazopyridazinone as PDE7 inhibitors. The SAR eluci-
dated that various groups with H-bond donor and/or acceptor at
the R2 position of III provided potent PDE7 inhibitors. We also
identified compound 7 which had adequate CNS penetration upon
i.p. administration in mice and that allowed it to be tested in the
in vivo models of PD. In the MPTP treated mice model of PD, com-
pound 7 produced a statistically insignificant dose dependent effi-
cacy. However, no effect was observed at the highest dose tested.
In addition, compound 7 produced modest catalepsy at the highest
dose tested and potentiated the cataleptic and motor deficit effects
of haloperidol at sub-optimal doses in mice. Therefore, it could be
anticipated that the beneficial effect of PDE7 inhibition to increase
the cAMP levels in striatal direct pathway was overshadowed by its
effect in the indirect pathway. This differential pharmacology
might result in a challenge of titrating an optimal dose for varied
human PD population. Therefore detailed preclinical studies are
warranted before concluding the potential therapeutic utility of
PDE7 inhibitors in PD.
Vehicle + Halo 0.1 mg/kg
Compound 7 1 mg/kg + Halo 0.1 mg/kg
Compound 7 3 mg/kg + Halo 0.1 mg/kg
Compound 7 10 mg/kg + Halo 0.1 mg/kg
180
160
140
120
100
80
*
**
**
*
60
40
20
0
0.5
1.0
Time post Haloperidol (h)
Acknowledgements
Figure 4. Effect of compound 7 on HIC test in male C57BL/6 mice. ⁄p <0.05, ⁄⁄p <0.01
versus vehicle + Halo by one-way Anova/Tukey’s test.
We thank the scientists from the analytical support group for
their help in compound characterization. We also gratefully
acknowledge the scientific services of Dr Daniel Small and Dr Ra-
chel Feldman of Numira Biosciences, Bothell, WA, USA.
of 1, 3 and 10 mg/kg (i.p.). In contrast, haloperidol (0.1, 0.3 and
0.9 mg/kg, s.c.) produced significant dose dependent catalepsy in
mice (Fig. 3). Moreover, pretreatment with sub-optimal potency
doses7 of compound 7 (1, 3, 10 mg/kg) significantly potentiated
the cataleptic effect of haloperidol (0.1 mg/kg, s.c.) in a saturating
manner (Fig. 4). The sub-optimal potency dose of compound 7
(3 mg/kg, i.p.) in combination with sub-cataleptic dose of haloper-
idol (0.1 mg/kg, s.c.) also resulted in significant motor deficits in
rotarod test in mice (Supplementary Fig. 1).17 These results suggest
that increased cAMP signaling with PDE7 inhibitors in the ‘striatal
indirect pathway’ can potentially produce modest catalepsy. The
present result further corroborate previous findings of potentiation
of the haloperidol induced catalepsy by PDE inhibitors (PDE4
inhibitor Rolipram, PDE1 inhibitor Vinpocetine) in rodent spe-
cies.18 In addition, PDE4 and PDE10 inhibitors which are being
developed as potential anti-psychotics are reported to produce
modest cataleptic motor deficits in a dose-independent manner.18
Thus the present results suggest that the differential pharmacology
of PDE7 inhibitors through both direct and indirect striatal path-
ways might be partly responsible for dose dependent self-limiting
blunted effects in rodent PD models. Further it can be suggested
that even modest cataleptic motor deficit is unwarranted for a po-
tential therapeutic of PD.
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.
07.077.
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number of counts was proportional to the time spent rearing.
6. Bergmann, J. E.; Cutshall, N. S.; Demopulos, G. A.; Florio, V. A.; Gaitanaris, G.;
Gray, P.; Hohmann, J.; Onrust, R.; Honhkui, Z. U.S. Pat. Appl. 2010, US 0113486.
7. Optimal potency dose is defined as the dose producing free drug concentration
in brain equivalent to mouse PDE7 IC50 value.
15. Boulay, D.; Bergis, O.; Avenet, P.; Griebel, G. Neuropsychopharmacol. 2010, 35,
416. The effect of compound
cataleptogenic activity was assessed in catalepsy bar test at 0.5 and 1 h post
administration. Compound and haloperidol were administered as
7 per se and on haloperidol induced
7
8. Banerjee, A.; Yadav, P. S.; Bajpai, M.; Sangana, R. R.; Gullapalli, S.; Gudi, G. S.;
Gharat, L. A. Bioorg. Med. Chem. Lett. 2012, 22, 3223.
9. (a) Vergne, F.; Bernardelli, P.; Chevalier, E. Annu. Rep. Med. Chem. 2005, 40, 227;
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2008, 18, 1127.
10. Gres’ko, S. V.; Smolyar, N. N.; Yutilov, Y. M. Russian J. Org. Chem. 2001, 1026, 37.
11. See Supplementary data for synthetic details of compound 7, 8 and 9.
12. (a) Sette, C.; Iona, S.; Conti, M. J. Biol. Chem. 1994, 269, 9245; (b) Hetman, J. M.;
Soderling, S. H.; Glavas, N. A.; Beavo, J. A. Proc. Natl. Acad. Sci. 2000, 97, 472.
13. Mouse brain homogenate binding was determined by High Throughput
intraperitonealy (i.p.) and subcutaneously (s.c.), respectively. Cataleptic-like
behavior was addressed by positioning the mouse in an upright position with
its forepaws resting on a horizontal bar (0.5 cm diameter) fixed at 4 cm height
above the surface of the bench. The time during which each mouse maintained
this position (the two front paws resting on the bar) was recorded up to a
maximum of 300 sec. The latency for mice to remove the forepaws and climb
down to a normal posture was recorded. In the combination study, compound
7 was pretreated 15 min. prior to haloperidol administration.
16. (a) Onali, P.; Olianas, M. C.; Gessa, G. L. Mol. Pharmacol. 1985, 28, 138; (b)
Kaneko, M.; Sato, K.; Horikoshi, R.; Yaginuma, M.; Yaginuma, N.; Shiragata, M.;
Kumashiro, H. Prostaglandins Leukot. Essent. Fatty Acids 1992, 46, 53.
17. See Supplementary data.
Dialysis (HTD) at 1 lM concentration.
14. (a) Kurosaki, R.; Muramatsu, Y.; Kato, H.; Araki, T. Pharmacol. Biochem. Behav.
2004, 78, 143; (b) Fredriksson, A.; Plaznik, A.; Sundstrom, E.; Jonsson, G.;
Archer, T. Pharmacol. Toxicol. 1990, 67, 295. MPTP (4 Â 20 mg/kg in saline) was
injected to 8–10 week old male C57BL/6 mice subcutaneously in a single day at
2 h intervals 7 days prior to behavioral test. On day 5 and 6, the mice were
subjected to behavioral locomotor activity (Med Associates Activity Monitor
Env-520, software version 4.21) to assess the disease progression and
18. (a) Siuciak, J. A.; Chapin, D. S.; McCarthy, S. A.; Martin, A. N. Psychopharmacol.
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C.; Majchrzak, M. J.; Ramirez, A. D.; Schmidt, P. A.; Seymour, P. A.; Siuciak, J. A.;
Tingley, F. D., III; Williams, R. D.; Verhoest, P. R’.; Menniti, F. S. J. Pharmacol. Exp.
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allocation into treatment groups. On day 7, compound
7 and l-dopa/
benserazide were administered 15 and 30 min. prior to the test (MPTP study
was performed at Numira Biosciences, Bothell, WA, USA). Horizontal activity
was registered when mice move in the horizontal plane around the cage by
interruption of low grid of infra-red beams. Rearing was registered as the