Synthesis and activity of a new methoxytetrahydropyran derivative as dual cyclooxygenase-2/5-lipoxygenase inhibitor

Article abstract of DOI:10.1016/S0960-894X(02)00013-6

Dual COX-2/5-LO inhibitors are described as potential new therapeutic agents for inflammatory diseases. A surprisingly potent effect of a 5-LO pharmacophoric group on the COX-2 inhibition is presented as well as pharmacological in vitro and in vivo results.

Full text of DOI:10.1016/S0960-894X(02)00013-6

Bioorganic & Medicinal Chemistry Letters 12 (2002) 779–782
Synthesis and Activity of a New Methoxytetrahydropyran
Derivative as Dual Cyclooxygenase-2/5-Lipoxygenase Inhibitor
Sabine Barbey,a Laurence Goossens,b Thierry Taverne,b
Josephine Cornet,b Valerie Choesmel,a Celine Rouaud,a Gilles Gimeno,a
Sylvie Yannic-Arnoult,a Catherine Michaux,c Caroline Charlier,c
Raymond Houssinb and Jean-Pierre Henichartb,*
aLaboratoires Innothera, avenue P. Vaillant-Couturier, BP 10, 94110 Arcueil, France
bInstitut de Chimie Pharmaceutique Albert Lespagnol, EA 2692, rue J. Laguesse, BP 83, 59006 Lille, France
c
´
´
Laboratoire de Chimie Moleculaire Structurale, Facultes Universitaires Notre-Dame de la Paix,
rue de Bruxelles, 5000 Namur, Belgium
Received 30 May 2001; revised 21 November 2001; accepted 20 December 2001
Abstract—Dual COX-2/5-LO inhibitors are described as potential new therapeutic agents for inflammatory diseases. Asurprisingly
potent effect of a 5-LO pharmacophoric group on the COX-2 inhibition is presented as well as pharmacological in vitro and in vivo
results. # 2002 Elsevier Science Ltd. All rights reserved.
Introduction
concentrations would have the potential to provide
more complete relief for patients suffering from arthritis
and inflammatory, hypersensitivity, dermatological or
cardiovascular disorders.14 Only a few compounds were
designed to inhibit both COX-2 and 5-LO enzymes and
this should have a synergistic effect on the reduction of
the inflammatory process.15,16 Our effort to find potent
in vitro but also orally active inhibitors has led us to
explore the new series of compounds 1–5.
Non-steroidal anti-inflammatory drugs are widely used
in the treatment of pain and inflammation.1 These
compounds non selectively inhibit the two isoforms
of the cyclooxygenase (COX-1 and COX-2) and thus
prevent the upregulation of prostaglandin formation,
which otherwise lead to an increase of vascular perme-
ability, edema, hyperalgesia, pyrexia and inflamma-
tion.2À5 Recently, it was demonstrated that COX-2
selective inhibitors may relieve the symptoms in these
pathologies while exhibiting a safer toxicity profile.6À9
The other major route of arachidonic acid (AA) meta-
bolism is the lipoxygenase pathway which generates
leukotrienes (LTs). LTB4 and the cysteinyl-leukotrienes
have powerful pro-inflammatory properties and the
inhibition of this metabolic pathway led to the develop-
ment of new therapeutic treatments for pathologies such
as asthma, allergies and other inflammatory dis-
orders.10À12 It has been pointed out that inhibiting only
one of these biosynthetic ways could shunt the meta-
bolism of AA towards the other pathway, thus lead-
ing to potential side effects.13 Pharmacologically
active compounds that inhibit both enzymes at similar
In compound 1, the pyrazole of the COX-2 inhibitor
Celecoxib is substituted at position 3 by the pharmaco-
phoric group 4-(3-fluoro-5-oxy)phenyl-4-methoxyte-
trahydropyran of ZD-2138, a 5-LO inhibitor from
Zeneca. This compound presents an excellent overall
biological profile.
*Corresponding author. Tel.:+33-3-2096-4374; fax:+33-3-2096-4361;
e-mail: henicha@phare.univ-lille2.fr
0960-894X/02/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved.
PII: S0960-894X(02)00013-6

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S. Barbey et al. / Bioorg. Med. Chem. Lett. 12 (2002) 779–782
Structure–Activity Relationships and Drug Design
Table 1. Comparison of COX-1, COX-2 and 5-LO inhibitory
activities
The original idea was to verify that the combination of
the pharmacophores of the COX-2 and 5-LO inhibitors
on a molecule would give a dual inhibitor. The chosen
groups were the classic tricyclic sulfonamide (Celecoxib-
like) as the COX-2 part17,18 and the 4-methoxytetrahy-
dropyran substituent of ZD-2138. This compound was
selected because it was devoid of redox and iron-chelat-
ing properties. It should be less prone to cause undesir-
able side effects. Comparison with the reference
compounds, Zileuton (a 5-LO inhibitor) and Rofecoxib
or NS-398 (COX-2 selective agents) showed a potent
COX/5-LO inhibition and a high COX-2 selectivity of
compound 1 (Table 1).
Compd
COX-1
COX-2
COX-1/COX-2
selectivity
5-LO
IC50 (mM)c
IC50 (mM)a IC50 (mM)b
Rofecoxib
NS-398
Zileuton
1
>10
3.0
>10
>10
0.001
0.001
>10
0.05
>1000
>1000
nsd
>10
>10
2.9
>200
0.003
aValues determined using monocytes-like cells.
bValues determined using osteosarcomes.
cValues determined using granulocytes-like cells. Each IC50 value
corresponds to an average of at least two independent experiments
performed in duplicate. Experiments were performed using the
classical procedures described in the literature.19À25
dNon selective.
The idea of pharmacophoric combination was already
developed by Searle26 for pyrazoles (Searle 1, Table 2)
and oxazoles (Searle 2, Table 2), possessing a selectivity
COX-2/COX-1 but a weak 5-LO inhibition.
Table 2. In vitro potency
Compd
COX-1
COX-2
5-LO
IC50 (mM)a IC50 (mM)a IC50 (mM)b
Nevertheless, the in vitro results were not confirmed in
vivo. Indeed, the most active compound (Searle 2) is
weakly active on the rat paw edema model (15% inhibi-
tion at 10 mg/kg per os).28 To rationalise the importance
of the various substituents, compounds 2–5 were prepared
(Table 3). They do not inhibit the cyclooxygenases and
have no or low potency as 5-LO inhibitors. Incorporation
of the methoxytetrahydropyran moiety increases 5-LO
potency which might be expected but surprisingly also
provide potent and selective COX-2 inhibition.
38
<0.1
0.15
1.3
<0.1
0.30
Docking of 1 in the active site of human COX-2, mod-
elled from the corresponding crystallised one of mouse,
was performed with DISCOVER module (CVFF force-
field) of Biosym software.29 In one of the most stable
(À52.87 kcal/mol) binding mode (Fig. 1), the sulfone
group fills the specific hydrophilic pocket (with Val523)
and forms H bond with Arg513. These molecular mod-
elling studies correlate well with established results30
and more recent data.31 In addition, the 5-LO pharma-
cophoric group fits well into the N/E region of the
active site. This small lipophilic cavity, where are situ-
ated Phe209, Val228, Ile377, Phe381, Phe529, Leu534, is
identical in COX-1 and 2. H bond is observed between
the methoxy group and Ser530.
aProstaglandin E2 inhibition was measured using recombinant COX-1
and COX-2 prepared as described by Gierse.27
bThe 5-LO activity of the compounds was determined by the inhibi-
tion of calcium ionophore-induced leukotriene B4 produced in human
blood.
Table 3. Comparison of COX-1, COX-2 and 5-LO inhibitory activi-
tiesa of compounds 1–5 using monocytes-like, osteosarcomes and
granulocytes-type cells, respectively
Compd
COX-1
IC50 (mM)
COX-2
IC50 (mM)
COX-1/COX-2
selectivity
5-LO
IC50 (mM)
1
2
3
4
5
>10
>10
>10
>10
>10
0.05
>10
>10
>10
10.0
>200
nsb
0.003
40.0
6.0
>10
>10
nsb
Chemistry
nsb
nsb
The diarylpyrazole backbone was prepared from an
phenylalkynone for compounds 2 and 3 and the corre-
sponding 4-methylsulfonylphenylhydrazine and acetic
acid in refluxing EtOH (Scheme 1). The second method
aEach IC50 value corresponds to an average of at least two independent
experiments performed in duplicate.
bNon selective.

S. Barbey et al. / Bioorg. Med. Chem. Lett. 12 (2002) 779–782
781
Scheme 1. Synthesis of the diarylpyrazoles.
Animals
Male Wistar rats 150Æ20 g body weight were used. The
rats were divided in three groups of nine. Group 1:
control; group 2: reference compound (NS-398); and
group 3 received compound 1. Inflammation was
induced by topical application of 25 mL of 25% AA in
acetone to the internal face of the left ear. The right
ear (control) received acetone (25 mL). Either AA
solution or acetone were applied with an automatic
pipette.
Treatment
For oral administration, the drugs were dissolved in
carboxymethylcellulose 1%. The treatment was admini-
stered 2 h before AA application. For intravenous
administration, the drugs were dissolved in dimethyl
sulfoxide and injected (via penile vein) 15 min before
AA application. In that case, intravenous administra-
tion was carried out under isoflurane anaesthesia.
Figure 1. Molecule 1 in the COX-2 active site.
involved the same hydrazine and ethyl (2,4-dioxo-4-
phenyl)butanoate 7.
Compound 4 was reduced in the presence of LiAlH4 in
anhydrous THF yielding the 1-(4-methylsulfonylphe-
nyl)-5-phenyl-1H-pyrazole-3-methanol 5. The alcohol
was then mesylated in the presence of NEt3 in CH2Cl2
and reacted with 3-fluoro-5-[4-(4-methoxytetrahy-
dropyranyl)]phenol26 and Cs2CO3 in DMF at 80 ꢀC
(Scheme 2) to yield 3-(3-fluoro-5-[4-(4-methoxytetrahy-
dropyranyl)]phenoxymethyl)-1-(4-methylsulfonylphenyl)-
5-phenyl-1H-pyrazole 1.
Experiments and results
One hour after AA application, the animals were
anaesthetised. A5-mm punch biopsy was performed on
each ear. Edema induced by AA was assessed as the
difference on weight between left and right ears. Intra-
venous administration of compound 1 led to a strong
reduction of AA-induced ear edema. Indeed, compound
1 (0.01 or 0.1 mg/kg) decreased edema by 41 and 44%,
respectively. Oral administration of 1 (0.1 and 5 mg/kg)
showed a similar effect because the edema was reduced
by 54 and 41%, respectively. The implication of both
5-LO and COX-2 pathways were checked in animals
pretreated with Zileuton and Rofecoxib. In such cases,
the maximal inhibitory effect reached about 40%.
Pharmacology
In vivo efficacy was evaluated in the model of arachi-
donic acid-induced ear edema in rat.

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S. Barbey et al. / Bioorg. Med. Chem. Lett. 12 (2002) 779–782
Scheme 2. Synthesis of the 3-(3-fluoro-5-[4-(4-methoxytetrahydropyranyl)]phenoxymethyl)-1-(4-methylsulfonylphenyl)-5-phenyl-1H-pyrazole 1.
Conclusion
Meeting, Las Vegas, USA, 7–11 Sept. American Chemical
Society: Washington, DC, 1997; MEDI 091.
15. Janusz, J. M.; Young, P. A.; Ridgeway, J. M.; Scherz,
M. W.; Enzweiler, K.; Wu, L. J. Med. Chem. 1998, 41, 1112.
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M.; Steber, M. J. Pharmacol. Exp. Ther. 1997, 282, 1094.
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Anew dual inhibitor of COX-2 and 5-LO has been
prepared. Apowerful pharmacophoric groupement that
can improve the inhibitory activity of a molecule on
both COX-2 and 5-LO in vitro and in vivo has been
demonstrated. This finding is in accordance with the
previous observations made on Searle sulfonamide-sub-
stituted pyrazoles. We have also pointed out that 3-alkyl
-1-(4-methylsulfonylphenyl)-5-phenyl-1H-pyrazoles do not
show any activity against COX-2 in our tests.
21. Reid, G. K.; Kargman, S.; Vickers, P. J.; Mancini, J. A.;
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