NO-donor COX-2 inhibitors. New nitrooxy-substituted 1,5-diarylimidazoles endowed with COX-2 inhibitory and vasodilator properties

Article abstract of DOI:10.1021/jm0607247

A series of NO-donor diarylimidazoles derived from the lead compound Cimicoxib were synthesized and evaluated for their COX-2 inhibitory activity and their stability in whole blood as well as for vasodilator properties. The products are partly transformed

Full text of DOI:10.1021/jm0607247

J. Med. Chem. 2007, 50, 1449-1457
1449
Articles
NO-Donor COX-2 Inhibitors. New Nitrooxy-Substituted 1,5-Diarylimidazoles Endowed with
COX-2 Inhibitory and Vasodilator Properties
Konstantin Chegaev,† Loretta Lazzarato,† Paolo Tosco,† Clara Cena,† Elisabetta Marini,† Barbara Rolando,†
Pierre-Alain Carrupt,‡ Roberta Fruttero,† and Alberto Gasco†,*
Dipartimento di Scienza e Tecnologia del Farmaco, UniVersita` degli Studi di Torino, Via Pietro Giuria 9, 10125 Torino, Italy, and Unite´ de
Pharmacochimie, Section des sciences pharmaceutiques, UniVersite´ de Gene`Ve, UniVersite´ de Lausanne, 30 Quai Ernest Ansermet, CH-1211
Gene`Ve, Switzerland
ReceiVed June 15, 2006
A series of NO-donor diarylimidazoles derived from the lead compound Cimicoxib were synthesized and
evaluated for their COX-2 inhibitory activity and their stability in whole blood as well as for vasodilator
properties. The products are partly transformed into the corresponding alcohols following 24-h incubation
in whole blood. All of them display good COX-1/COX-2 selectivity, but are less potent than the lead; a
molecular modeling study was carried out to investigate their binding mode. The compounds are also capable
of relaxing rat aorta strips precontracted with phenylephrine with a NO-dependent mechanism; this property
could confer reduced cardiotoxicity with respect to traditional COX-2 inhibitors.
Chart 1. Examples of Diarylheterocyclic COX-2 Inhibitors
Introduction
COX-2 selective inhibitors (coxibs) are an important class
of drugs useful for the treatment of acute pain and chronic
inflammatory diseases. They are characterized by reduced
gastrotoxicity with respect to classical nonsteroidal antiinflam-
matory drugs (NSAIDs), due to their capacity of sparing the
COX-1 isoform of the cyclooxygenase enzyme (COX).1,2
Moreover, these products are under study for the treatment of
certain forms of cancer and Alzheimer’s disease.3,4 The most
important coxibs belong to the diarylheterocycle class and bear
two phenyl rings on adjacent atoms of a five- or six-membered
heterocyclic system. One of the two phenyl rings must be
p-methylsulfonyl or p-aminosulfonyl substituted in order to
achieve COX-2 selectivity, while different substitution patterns
are allowed in the other. The RSO2 (R ) NH2, CH3) moiety
establishes a hydrogen bonding interaction with the Arg513
residue that is present in the active cleft of the COX-2 isoform,
in place of the His513 residue present in the COX-1 isoform.5
Examples of such drugs developed by different companies are
reported in Chart 1 (Celecoxib 1,6 Rofecoxib 2,7 Valdecoxib
3,8 Cimicoxib 49). Rofecoxib, Valdecoxib, and Celecoxib were
the first products to be introduced in therapy. During the clinical
use of these drugs it became more and more evident that they
increase the risk of heart attack and stroke. This cardiotoxicity
is due to their capacity to reduce the biosynthesis of prostacy-
cline (PGI2), with consequent tipping of the eicosanoid balance
in favor of thrombogenic thromboxanes (e.g., TxA2).10 Conse-
quently, the first two drugs have been withdrawn from the
market and Celecoxib is under surveillance.11,12 The cardiovas-
cular implications of COX-2 inhibitors are currently the object
of debate, and they limit the clinical application of these
molecules. The concept of multitarget drug can be usefully
applied to obtain safer COX-2 inhibitors. A multitarget drug is
Chart 2. General Structure of Nitrooxyalkyl COX-2 Selective
Inhibitors
designed through the symbiotic approach by joining two drugs,
or crucial parts of them, according to different schemes.13 For
example, the appropriate conjugation of a COX-2 inhibitor with
a thromboxane antagonist could give rise to a drug able to block
thromboxanes and other thromboxane receptor agonists in
addition to PG synthesis, thus limiting the prostacycline/
thromboxane imbalance.10 Another possibility is the design of
a COX-2 selective inhibitor bearing an appropriate NO-donor
moiety. In fact, nitric oxide triggers multiple actions at the level
* To whom correspondence should be addressed. Tel: +39-011-670-
7670. Fax: +39-011-670-7286. E-mail: alberto.gasco@unito.it.
† University of Torino.
‡ University of Gene`ve.
10.1021/jm0607247 CCC: $37.00 © 2007 American Chemical Society
Published on Web 03/03/2007

1450 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 7
ChegaeV et al.
Scheme 1a
a Reagents and conditions: (i) BBr3, ClCH2CH2Cl, reflux; (ii) (EtO)2CHNMe2, RT; (iii) Br(CH2)nOTBDMS, K2CO3, MeCN, reflux; (iv) 2 N NaOH,
MeOH, 40 °C; (v) 1 N HCl, MeOH; (vi) Ph3P, NBS, AgNO3, MeCN, 0 °C, and then 60 °C; (vii) TsCl, Py, 0 °C; (viii) 13, t-BuOK, THF, 60 °C; (ix) AllBr,
NaH, THF, reflux; (x) I2, AgNO3, MeCN, RT, and then reflux.

NO-Donor COX-2 Inhibitors
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 7 1451
Scheme 2. Metabolic Fate in Human Whole Blood
Table 1. Stability Following 24-h Incubation in Human Serum and in
Human Whole Blood
human serum
human whole blood
%
% unchanged
% metabolites
t1/2
compd
unchanged
((SE)
((SE)
(h)
8
9
11
14
16
>98
>98
>98
>98
>97
58.8 ((3.4)
64.1 ((2.4)
53.3 ((2.9)
60.6 ((1.5)
43.6 ((3.9)
8a: 43.4 ((2.2)
9a: 37.2 ((2.0)
11a: 45.9 ((1.0)
14a: 44.8 ((1.5)
16a + 16b: 47a
16c: 14a
28.1
39.2
27.1
37.5
21.0
a Quantitative assessment was performed using the calibration curve of
compound 16 since no standards were available.
of the cardiovascular system, namely vasodilation, platelet
aggregation inhibition, and modulation of the platelets and
leucocytes adhesion to the endothelium,14 thus potentially
alleviating the cardiovascular issues raised by common coxibs.
Moreover, the increased mucosal blood flow and thickening of
the mucous layer induced by NO on the stomach walls can
contribute to the gastro-sparing features of COX-2 selective
inhibitors.15 Examples of NO-donor cyclooxygenase inhibitors
have already been reported in literature, both nonselective
(CINODs)16 and COX-2-selective (Chart 2).17 The latter have
a therapeutic potential not only as safer drugs for the treatment
of pain and inflammation but also in a wide variety of disease
states.18 In particular, they could be useful in cancer prevention
in view of their ability to inhibit cell proliferation and cancer
cell progression by a dual NO/COX-2-dependent mechanism.19
As a development of our previous works, in this paper we
describe the synthesis, the COX inhibition profile, and vasodi-
lator activities of a series of analogues of the lead compound
Cimicoxib9 (4), which is presently undergoing Phase I clinical
trials, and its methylsulfonyl analogue 5. These analogues have
been designed by substituting the 4-methoxy group present in
the lead with NO-donor nitrooxy-substituted alkyloxy chains
(derivatives 8, 9, 11, 14, 16). Metabolism of these products in
human whole blood and their docking in the active cleft of both
COX isoforms are also discussed.
Chemistry. Cimicoxib (4) was used as starting material for
the preparation of its NO-donor derivatives (Scheme 1). This
product was refluxed in 1,2-dichloroethane in the presence of
BBr3; the resulting phenol derivative 6 was reacted with N,N-
dimethylformamide diethylacetal to give 7. This intermediate,
in which the sulfonamido group is protected in order to avoid
its possible alkylation, was sequentially heated in acetonitrile
in the presence of K2CO3 with the appropriate (bromoalkoxy)-
(tert-butyl)dimethylsilane (Br(CH2)nOTBDMS) and then treated
with NaOH in MeOH to regenerate the sulfonamido group and
ultimately with HCl to cleave the silyl protection. The resulting
alcohols 8a, 9a were transformed into the corresponding nitrates
8, 9 by action of triphenylphosphine, N-bromosuccinimide
(NBS), and AgNO3 in acetonitrile solution. The p-methylsul-
fonyl-substituted compound 5 was used as starting material for
the preparation of the final nitrates 11, 14, 16. This product
was transformed into the corresponding phenol 10 following
the procedure used to prepare 6 from 4. The reaction of 10 with
(2-bromoethoxy)(tert-butyl)dimethylsilane in acetonitrile in the
presence of K2CO3, followed by treatment with HCl yielded
the intermediate 11a that, under the same conditions used to
prepare 8 from 8a, gave 11. Treatment of 10 in tetrahydrofuran
(THF) with the tosylate 13, obtained by action of p-toluensul-
fonyl chloride in pyridine on 12, and potassium tert-butoxide,
afforded the expected final nitrate 14. The alcohol 14a was
obtained from 10 following a procedure similar to that used
for the preparation of 11a from 10. The synthesis of the final
dinitrooxy compound 16 required the preparation of the allyloxy-
substituted intermediate 15. The latter was easily obtained by
refluxing a THF solution of 10, allyl bromide (AllBr), and NaH.
The treatment of a mixture of AgNO3 and 15 with iodine in
acetonitrile at room temperature followed by reflux, according
to a known procedure to prepare vicinal dinitrooxy-substituted
compounds,20 afforded the expected final compound 16. The
presence of the sulfonamido function precluded the synthesis
of the corresponding dinitrooxy analogue of Cimicoxib starting
from 6, through a sequence of similar reactions.
Results and Discussion
Metabolism in Serum and Human Whole Blood. Organic
nitrates can undergo chemical and enzymatic metabolism.21 All
the nitrates studied in the present work were found to be stable
following 24-h incubation in human serum. By contrast, they
are partly transformed into the corresponding alcohols when
incubated for 24 h in human whole blood (Table 1). This
transformation was monitored by RP-HPLC; in the case of the
mononitrooxy derivatives the metabolites could be identified
with alcohols 8a, 9a, 11a, 14a by comparing their retention
times with the standards at our disposal; LC/MS confirmed this
finding. The availability of internal standards allowed precise
quantitative assessment of the extent of metabolism, which
displays a slight dependence on the structure of the products.
The less lipophilic mononitrooxyethyl-substituted compounds
were metabolized just a little faster than the related mononi-
trooxypropyl analogues. In the case of the dinitrooxy-substituted
product 16 a mixture of three metabolites was formed, which
were characterized by LC/MS due to the lack of internal
standards. Two of them showed the same molecular weight,
identical to that of the two corresponding monohydroxy isomers
16a and 16b, while the third had the molecular weight of the
corresponding dihydroxy analogue 16c (Scheme 2).
COX Inhibition. The ability of the products to inhibit COX
isozymes was evaluated in human whole blood according to a
well-established procedure.22 To assess the extent of COX-2
isoform inhibition, human heparinized whole blood was incu-
bated overnight with lipopolysaccharide (LPS) in the presence
of the inhibitors, and then plasma was assayed for PGE2
production. For COX-1 inhibitory activity, whole blood samples
without any anticoagulant were incubated with the inhibitors
for 1 h and then serum was collected and analyzed for TxB2
production. The potencies of the products expressed as IC50 are
collected in Table 2. Since the products proved to be partly
metabolized over 24 h in whole blood into the corresponding
alcohols, we also measured the inhibitory potencies of the
monohydroxy metabolites 8a, 9a, 11a, 14a at our disposal.

1452 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 7
ChegaeV et al.
Table 2. Experimental Inhibitory Potencies, Vasodilator Activities, and Calculated ∆G Values
COX-2
COX-1
COX-2
a
a
b
c
compd
ISDN
IC
IC
vasodilation, EC50
∆G
MM-GBSA
50
50
-
-
4.7 ( 0.6
-
>100d
55 ( 10e
-
-
1
2
4
5
8
1.3 ( 0.4
1.5 ( 0.8
0.10 ( 0.03
0.090 ( 0.019
29 ( 4
14 ( 2
-
-
64 ( 13
1.9 ( 0.2
5.8 ( 0.9
25 ( 3d
24 ( 2d
0.051 ( 0.006
12 ( 2d
-
-37.44
-35.89
-30.81
>100
8a
9
20 ( 8
16 ( 7
>100
>100
>100
>100
-
0.10 ( 0.02
-30.17
-
18 ( 2d
9a
11
>100
-
6.9 ( 2.0
0.021 ( 0.004
6.5 ( 1.1d
-
0.078 ( 0.014
6.3 ( 0.6d
-
-30.85
11a
14
56 ( 10
14 ( 3
>100
>100
-
-30.87
14a
16
>100
76 ( 18
>100
>100
-
0.021 ( 0.003
-28.88f
>100d
0.061 ( 0.006e
a Values reported as IC50 (µM) ( SEM. b Values reported as EC50 (µM) ( SEM. c kcal/mol, evaluated through a simplified MM-GBSA approach which
neglects the entropic term in the ∆Gbinding calculation. d In the presence of 1 µM ODQ. e In the presence of 10 µM HbO2. f Since the compound exists as a
couple of enantiomers, whose ratio is unknown, the calculated ∆G is reported as the average ∆G of the two docked enantiomers, which indeed showed very
close values.
Figure 1. Superposition of docked ligands inside the COX-2 active site. Since their alcoholic metabolites display binding poses very similar to
those of the parent compounds, they have not been included for clarity. Reference compounds 4, 5 are colored in orange. Protein carbon atoms are
colored in gray to distinguish them from ligand carbons. Nonpolar hydrogens have been omitted for clarity, except for the ligand methylsulfonyl
group. A green dotted line evidences the hydrogen bond between the ligand sulfonyl group and Arg513. This figure was generated with PyMOL.33
Analysis of the data reported in Table 2 indicates that all the
new NO-donor COX inhibitors retain a high degree of selectivity
for the COX-2 isoform but are definitely less potent than the
parent compounds 4, 5. The metabolites display activities similar
to or lower than those of the parent structures. The most active
product is the nitrooxyethyloxy-substituted compound 11, about
5 and 80 times less active than Rofecoxib (2) and its imidazole
parent 5, respectively.
Molecular Modeling. A molecular modeling study was
performed in the attempt to explain the lower COX-2 inhibitory
activity found for the NO-donor hybrids and their metabolites
with respect to that of the lead compounds 4 and 5. The
cocrystallized ligand coordinates were removed from the Protein
Data Bank records of the two isozymes (PDB codes 1cx2 and
1q4g), and flexible docking of all inhibitors, including their
metabolites, and reference compounds 4, 5 was accomplished

NO-Donor COX-2 Inhibitors
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 7 1453
into the two active sites (see Experimental Section and Sup-
porting Information for details). None of the products showed
any significant complementarity with the COX-1 active site.
By contrast, all newly synthesized ligands display a binding
mode to the COX-2 active site similar to that of the lead
compounds. In particular, the lowest energy poses display a
strong hydrogen bond between Arg513 and an oxygen atom
belonging to the sulfonyl group (Figure 1), which is known to
be one of the determinants of COX-2 selectivity.5 The amino
group of aminosulfonyl-substituted compounds establishes
hydrogen bonds with the carbonyl oxygen of Ser353 and
Gln192, while methylsulfonyl analogues find hydrophobic
contacts with Ile517 and Phe518. Due to the increased steric
bulk of the substituted alkoxy chain with respect to the methoxy
group, all newly synthesized ligands are forced to bind less
deeply in the COX-2 active site than the reference molecules
(Figure 1). Consequently, favorable electrostatic interactions
between the fluorine atom and the hydroxyl group of Ser530
are partially compromised, as well as the hydrophobic interac-
tions between the chlorine atom and the side chains of Ala527
and Leu531. No stabilizing hydrogen bonding occurs between
the nitrate groups and the hydroxyl groups of Tyr348, Tyr385,
or Ser530, and the hydrophobic contacts with Trp387, Met522,
Val523 are not sufficient to counterbalance the strained geom-
etry that the nitrooxyalkyl chains must adopt to avoid steric
clashes with the surrounding residues. An analogous picture was
found for the hydroxy metabolites. In conclusion, steric
hindrance of ester or alcoholic side chains seems to account
for the lower inhibitory activity of newly synthesized compounds
and metabolites with respect to reference molecules, in agree-
ment with the structure-activity relationships reported by the
developers of Cimicoxib (4).9 The empirical free energy function
implemented in AutoDock, which includes terms accounting
for the desolvation free energy of the ligand and for its loss of
conformational degrees of freedom upon binding,23 was used
to score the ligands’ binding affinities. As already pointed out
by other investigators,24 the scoring function failed to rank the
COX-2 inhibitors according to their relative experimental
potencies. This failure can be ascribed to insufficient confor-
mational sampling or to the scoring function itself, too coarse
to discriminate between small energy differences inside a
homologous series of compounds. The docking poses were then
taken as a starting point for an implicit solvent MM-GBSA
simulation,25 in which the entropic term was omitted to reduce
the computational effort (see Supporting information). The
resulting ∆GMM-GBSA scores for the new NO-donor COX-2
selective inhibitors are shown in Table 2. As a whole, these
figures are definitely higher for the new NO-donor hybrids than
for the imidazole reference compounds, thus confirming the
reliability of the qualitative picture given by AutoDock.
moglobin (HbO2), a potent scavenger of nitric oxide, the same
decrease occurred for both 16, taken as example of the
compounds under study, and ISDN. These findings are in
keeping with the generally accepted vasodilator mechanism of
nitrates which involves their entry into vascular smooth muscle
cells where they are converted into NO, with the subsequent
activation of soluble guanylate cyclase (sGC).27 Interestingly,
also reference compounds 4 and 5, which are devoid of NO-
releasing properties, display vasodilator activity, but in a
concentration range definitely higher than that shown by the
related NO-donors. As expected, this activity is not ODQ-
dependent.
Conclusions. In this study the synthesis of a new class of
imidazole cyclooxygenase inhibitors containing NO-donor ni-
trooxy groups, structurally related to Cimicoxib (4), has been
reported. The new compounds were investigated for their
metabolism and for their COX-2 and COX-1 inhibitory activity
in whole blood. The nitrooxy functions undergo partial me-
tabolism over 24 h into the corresponding alcohols. The products
display a high degree of COX-2 vs COX-1 selectivity as well
as a good COX-2 inhibitory potency, although lower than the
leads; a molecular modeling study provided a sound explanation
to these findings. In addition to COX-2 inhibition, a potent,
NO-dependent vasodilator activity was assessed by an in vitro
functional assay. These products are worthy of additional studies
in view of their therapeutic potentialities in a wide variety of
disease states.
Experimental Section
Synthesis. 1H and 13C NMR spectra were recorded on a Bruker
Avance 300 at 300 and 75 MHz, respectively, using SiMe4 as the
internal standard. Low-resolution mass spectra were recorded with
a Finnigan-Mat TSQ-700. Melting points were determined with a
capillary apparatus (Bu¨chi 540). Flash column chromatography was
performed on silica gel (Merck Kieselgel 60, 230-400 mesh
ASTM); PE stands for 40-70 petroleum ether. The progress of
the reactions was followed by thin layer chromatography (TLC)
on 5 × 20 cm plates with a layer thickness of 0.2 mm. Anhydrous
magnesium sulfate was used as the drying agent for the organic
phases. Organic solvents were removed under vacuum at room
temperature. Preparative HPLC was performed on a Lichrospher
C
18 column (250 × 25 mm, 10 µm) (Merck Darmstadt, Germany)
with a Varian ProStar mod-210 with Varian UV detector mod-
325. Elemental analyses (C, H, N) were performed by REDOX
(Monza), and the results are within (0.4% of the theoretical values
unless otherwise stated. Compounds 4,9 5,9 1228 were synthesized
according to literature.
4-[4-Chloro-5-(3-fluoro-4-hydroxyphenyl)-1H-imidazol-1-yl]-
benzenesulfonamide (6). To a stirred suspension of 4 (0.20 g, 0.52
mmol) in dichloroethane (20 mL) kept at 0 °C was added a 1 M
solution of BBr3 in CH2Cl2 (5.5 mL, 5.5 mmol) dropwise. The
reaction mixture was refluxed for 2 h and then cooled in an ice
bath. A KHCO3 saturated solution (10 mL) was added dropwise to
the obtained suspension, and then the whole mixture was poured
into a KHCO3 saturated solution (20 mL) and stirred for 2 h at
room temperature. The precipitate was filtered off, washed with
cold water (10 mL), and dried. The analytically pure sample was
obtained by recrystallization from EtOH/H2O mixture. Yield 76%.
Vasodilator Activity. The in Vitro vasodilator activity of this
new series of selective NO-donor COX-2 inhibitors was assessed
on rat aorta strips precontracted with phenylephrine. All the
products were able to relax the contracted tissues in a dose-
dependent manner. Their potencies, expressed as EC50, are
collected in Table 2. All of them behave as potent vasodilators,
definitely more active than isosorbide dinitrate (ISDN), taken
as a reference.26 The most active products 11, 16 and the least
active 9 are about 200- and 50-fold more active than ISDN.
When the experiments were repeated in the presence of 1 µM
ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one), a well-
known inhibitor of soluble guanylate cyclase (sGC), a strong
decrease in the vasodilator potencies was observed. When the
experiments were performed in the presence of 10 µM oxyhe-
1
Mp 272-273 °C (EtOH/H2O); H NMR (DMSO-d6) δ: 6.81-
7.05 (m, 3H, C6H3), 7.44 (d, 2H, C6H4), 7.50 (s, 2H, NH2), 7.87
(d, 2H, C6H4), 8.09 (s, 1H, CH Im), 10.3 (br s, 1H, OH); 13C NMR
(DMSO-d6) δ: 117.4, 117.6, 117.8, 125.6, 125.8, 126.4, 126.8,
127.5, 136.6, 138.1, 143.5, 143.6, 145.2, 145.3, 148.8, 152.0; MS
(EI) 367/369 (M)+. Anal. (C15H11ClFN3O3S‚0.25H2O) C, H, N.
4-[4-Chloro-5-(3-fluoro-4-hydroxyphenyl)-1H-imidazol-1-yl]-
N-[(dimethylamino)methylene]benzenesulfonamide (7). To a
stirred solution of 6 (0.10 g, 0.27 mmol) in acetonitrile (5 mL)
was added N,N-dimethylformamide diethylacetal (52 µL, 0.29

1454 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 7
ChegaeV et al.
mmol). Stirring was continued for 1 h, and then the reaction mixture
was concentrated under reduced pressure. The oil thus obtained
was treated with cold water (5 mL), and the resulting white solid
was filtered off, washed with a small amount of cold water, and
dried. This product was used without any additional purification
for further reaction. Yield 87%. Mp 294-295 °C (MeCN); 1H NMR
(DMSO-d6) δ: 2.92 (s, 3H, CH3), 3.15 (s, 3H, CH3), 6.73-7.05
(m, 3H, C6H3), 7.38 (d, 2H, C6H4), 7.82 (d, 2H, C6H4), 8.23 (s,
1H), 8.44 (s, 1H) (NdCHNIm, CHIm), 10.2 (br s, 1H, OH); 13C
NMR (DMSO-d6) δ: 35.0, 40.9, 117.4, 117.6, 117.8, 117.9, 125.5,
125.8, 126.4, 127.1, 127.5, 136.6, 138.1, 142.6, 145.2, 145.4, 148.8,
152.0, 159.9; MS (EI) 422/424 (M)+.
126.9, 127.1, 128.4, 129.1, 137.5, 139.8, 145.1, 148.1, 148.2, 151.4,
154.7; MS (EI) 470/472 (M)+. Anal. (C18H16ClFN4O6S) C, H, N.
4-{4-Chloro-1-[4-(methylsulfonyl)phenyl]-1H-imidazol-5-yl}-
2-fluorophenol (10). The product was synthesized starting from 5
following a procedure similar to the one described for the
preparation of 6 from 4. Yield 83%. Mp 243-244 °C dec; 1H NMR
(DMSO-d6) δ: 3.29 (s, 3H, CH3), 6.82-7.09 (m, 3H, C6H3), 7.54
(d, 2H, C6H4), 8.02 (d, 2H, C6H4), 8.13 (s, 1H, CH Im), 10.29 (br
s, 1H, OH); 13C NMR (DMSO-d6) δ: 43.2, 117.5, 117.7, 117.8,
117.9, 125.6, 126.1, 126.5, 127.8, 128.3, 136.7, 139.7, 140.3, 145.3,
148.9, 152.1; MS (EI) 366/368 (M)+. Anal. (C16H12ClFN2O3S) C,
H, N.
2-{4-[4-Chloro-1-(4-(methylsulfonyl)phenyl)-1H-imidazol-5-
yl]-2-fluorophenoxy}ethanol (11a). The title product was synthe-
sized starting from 10 following a procedure similar to that used
to prepare 8a from 7, but without the final treatment with 20%
HCl. The oil obtained after removing the solvent under reduced
pressure was treated with water and extracted with EtOAc. The
organic layer was washed with water and brine, dried, and
evaporated under reduced pressure. The oily residue was triturated
with diethyl ether to give a solid that was collected by filtration.
Finally, the product was recrystallized from i-PrOH. Yield 83%.
4-{4-Chloro-5-[3-fluoro-4-(2-hydroxyethoxy)phenyl]-1H-imi-
dazol-1-yl}benzenesulfonamide (8a). To a stirred mixture of 7
(0.34 g, 0.80 mmol) and K2CO3 (0.33 g, 2.40 mmol) in acetonitrile
(10 mL) was added (2-bromoethoxy)-tert-butyldimethylsilane (0.30
mL, 1.40 mmol) in one portion. The reaction mixture was heated
at 70-75 °C for 8 h, it was concentrated under reduced pressure,
and sequentially MeOH (5 mL) and 2 N NaOH (2 mL) were added.
The resulting mixture was heated at 40 °C for 2 h and then acidified
to pH 1 with 20% HCl. The solvent was removed under reduced
pressure, and the residue was treated with water (10 mL) to give a
sticky precipitate that afforded a powder after a 2-h refrigeration.
The powder was filtered off, washed with water, and dried. An
analytically pure sample was obtained by recrystallization from
1
Mp 142-143 °C (i-PrOH); H NMR (CDCl3) δ: 2.75 (br s, 1H,
OH), 3.10 (s, 3H, CH3), 4.00 (m, 2H), 4.16 (m, 2H) (CH2CH2),
6.87-7.00 (m, 3H, C6H3), 7.34 (d, 2H, C6H4), 7.67 (s, 1H, CH
Im), 7.99 (d, 2H, C6H4); 13C NMR (CDCl3) δ: 44.4, 61.0, 70.7,
114.9, 117.4, 117.7, 119.8, 119.9, 125.7, 126.1, 129.2, 129.9, 135.6,
140.4, 147.1, 147.3, 150.5, 153.8; MS (EI) 410/412 (M)+. Anal.
(C18H16ClFN2O4S) H, N. C: calcd, 52.62; found, 53.23.
1
EtOH. Yield 98%. Mp 190-191 °C (EtOH); H NMR (CD3OD)
δ: 3.89 (t, 2H, CH2), 4.12 (t, 2H, CH2), 6.94-7.13 (m, 3H, C6H3),
7.43 (d, 2H, C6H4), 7.96 (d, 2H, C6H4), 7.98 (s, 1H, CH Im); 13C
NMR (CD3OD) δ: 61.4, 71.9, 115.9, 118.5, 118.8, 121.0, 121.1,
127.2, 127.4, 127.5, 127.7, 128.7, 129.4, 137.7, 140.1, 145.4, 148.8,
148.9, 151.8, 155.0; MS (EI) 411/413 (M)+. Anal. (C17H15-
ClFN3O4S‚H2O) C, H, N.
2-{4-[4-Chloro-1-(4-(methylsulfonyl)phenyl)-1H-imidazol-5-
yl]-2-fluorophenoxy}ethyl Nitrate (11). The title product was
synthesized starting from 11a following a procedure similar to that
used for the preparation of 8 from 8a. The product was partly
purified by flash chromatography (eluent PE/EtOAc 1/1 v/v) and
then by preparative HPLC (Lichrospher 250-25 C18, mobile phase
MeCN/H2O 1/1 v/v, flow-rate 39 mL/min, λ ) 254 nm) to give
the title compound as a white powder. Yield 35%. Mp 60-65 °C;
1H NMR (CDCl3) δ: 3.10 (s, 3H, CH3), 4.33-4.36 (m, 2H), 4.83-
4.86 (m, 2H) (CH2CH2), 6.86-7.01 (m, 3H, C6H3), 7.33 (d, 2H,
C6H4), 7.65 (s, 1H, CH Im), 7.99 (d, 2H, C6H4); 13C NMR (CDCl3)
δ: 44.4, 65.7, 70.7, 115.6, 117.8, 118.0, 120.9, 121.0, 125.5, 125.7,
126.1, 129.3, 130.2, 135.7, 140.3, 140.5, 146.3, 146.4, 150.7, 154.0;
MS (EI) 455/457 (M)+. Anal. (C18H15ClFN3O6S) C, H, N.
4-{4-Chloro-5-[3-fluoro-4-(2-hydroxypropoxy)phenyl]-1H-
imidazol-1-yl}benzenesulfonamide (9a). The product was obtained
by the same procedure as for 8a, using (3-bromopropoxy)-tert-
butyldimethylsilane. Yield 82%. Mp 194-195 °C (MeOH); 1H
NMR (CD3OD) δ: 2.00 (m, 2H, CH2CH2OH), 3.74 (t, 2H, 3JHH
)
6.2 Hz), 4.15 (t, 2H, 3JHH ) 6.1 Hz) (CH2CH2CH2OH), 6.94-7.11
(m, 3H, C6H3), 7.43 (d, 2H, C6H4), 7.94-7.97 (m, 3H, C6H4, CH
Im); 13C NMR (CD3OD) δ: 32.8, 58.9, 66.7, 115.4, 118.1, 118.4,
120.4, 120.5, 126.9, 127.2, 127.3, 127.4, 127.5, 128.4, 129.0, 129.4,
137.4, 139.8, 145.1, 148.6, 151.4, 154.7; MS (EI) 425/427 (M)+.
Anal. (C18H17ClFN3O4S) C, H, N.
3-(Nitrooxy)propyl 4-Methylbenzenesulfonate (13). 3-Hydrox-
ypropyl nitrate (12, 1.10 g, 9.10 mmol) was dissolved in dry
pyridine (10 mL) at 0 °C, and p-methylbenzenesulfonyl chloride
(2.50 g, 13.1 mmol) was added in one portion. The reaction mixture
was kept at 0 °C for 5 h, and then it was poured into 1 N HCl
solution and extracted with EtOAc. The organic layer was washed
with 1 N HCl solution and brine, dried, and evaporated under
reduced pressure. The resulting oil was purified by flash chroma-
tography (eluent PE/EtOAc 95/5 v/v) to give the title compound
3-{4-[1-(4-(Aminosulfonyl)phenyl)-4-chloro-1H-imidazol-5-
yl]-2-fluorophenoxy}ethyl Nitrate (8). To a stirred suspension of
8a (0.80 g, 1.95 mmol) in acetonitrile (25 mL) were added AgNO3
(0.66 g, 3.89 mmol) and Ph3P (0.75 g, 2.86 mmol). The reaction
mixture was cooled at 0 °C, and NBS (0.50 g, 2.80 mmol) was
added in one portion. The stirring was continued at 0 °C for 1 h
and then at 60 °C for 3 h. The reaction mixture was filtered, and
the filtrate was evaporated under reduced pressure. The yellow oil
thus obtained was purified by flash chromatography (eluent CH2-
Cl2/MeOH 98/2 v/v). Recrystallization from MeOH gave the title
compound as white solid. Yield 20%. Mp 191-193 °C dec
1
as a colorless oil which solidified upon standing. Yield 55%. H
NMR (CDCl3) δ: 2.08 (m, 2H, CH2CH2CH2), 2.45 (s, 3H, CH3),
3
3
4.12 (t, 2H, JHH ) 5.9 Hz), 4.46 (t, 2H, JHH ) 6.1 Hz) (CH2-
CH2CH2ONO2), 7.36 (d, 2H, C6H4), 7.78 (d, 2H, C6H4); 13C NMR
(CDCl3) δ: 21.7, 26.6, 65.8, 68.6, 127.9, 130.0, 132.5, 145.3; MS
(EI) 275 (M)+; the compound was not characterized through
elemental analysis due to its instability, but it was immediately
reacted in the following step.
1
(MeOH); H NMR (CD3OD) δ: 4.34-4.37 (m, 2H), 4.85-4.89
(m, 2H) (CH2CH2OH), 6.96-7.14 (m, 3H, C6H3), 7.43 (d, 2H,
C6H4), 7.94-7.98 (m, 3H, C6H4, CH Im); 13C NMR (CD3OD)
δ: 66.9, 72.4, 116.3, 118.7, 119.0, 121.8, 121.9, 127.2, 127.4, 127.7,
127.8, 128.7, 129.5, 129.9, 135.6, 137.9, 145.4, 148.0, 148.1, 151.7,
155.0; MS (CI) 457/459 (M + 1)+. Anal. (C17H14ClFN4O6S) C,
H, N.
3-{4-[4-Chloro-1-(4-(methylsulfonyl)phenyl)-1H-imidazol-5-
yl]-2-fluorophenoxy}propyl Nitrate (14). To a stirred solution of
10 (0.25 g, 0.68 mmol) in dry THF (15 mL), kept under nitrogen,
was added a solution of t-BuO-K+ (0.09 g, 0.75 mmol) in dry THF
(10 mL). The obtained mixture was stirred for 15 min at room
temperature, and then 13 (0.20 g, 0.72 mmol) was added in one
portion. The reaction was left under stirring for 0.5 h and then was
heated at 75 °C for 8 h. After this time, the mixture was poured
into 2 N NaOH (20 mL) and extracted with CH2Cl2. The organic
layers were washed with water and brine, dried, and evaporated
under reduced pressure. The residue was purified by flash chro-
3-{4-[1-(4-(Aminosulfonyl)phenyl)-4-chloro-1H-imidazol-5-
yl]-2-fluorophenoxy}propyl Nitrate (9). The product was obtained
by the same procedure as for 8, using 9a as the starting compound.
The title product was recrystallized from EtOH. Yield 15%. Mp
169.5-170.5 °C dec (EtOH); 1H NMR (CD3OD) δ: 2.23 (m, 2H,
3
3
CH2CH2ONO2), 4.16 (t, 2H, JHH ) 5.9 Hz), 4.69 (t, 2H, JHH
)
6.3 Hz) (CH2CH2CH2ONO2), 6.95-7.12 (m, 3H, C6H3), 7.43 (d,
2H, C6H4), 7.94-7.98 (m, 3H, C6H4, CH Im); 13C NMR (CD3OD)
δ: 27.6, 70.9, 73.7, 115.6, 118.0, 118.2, 118.5, 118.7, 121.0, 121.1,

NO-Donor COX-2 Inhibitors
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 7 1455
matography (eluent CH2Cl2/EtOAc 8/2 v/v) to give the pure title
compound as a colorless oil which solidified upon drying. Yield
41%. Mp 80-83 °C; 1H NMR (CDCl3) δ: 2.26 (m, 2H, CH2CH2-
quantitation of unchanged compounds and metabolites. HPLC
analyses were performed with a HP1100 chromatograph system
(Agilent Technologies, Palo Alto, CA) equipped with a quaternary
pump (model G1311A), a membrane degasser (model G1379A),
and a diode-array detector (DAD) (model G1315B) integrated in
the HP1100 system. Data analysis was accomplished using a HP
ChemStation system (Agilent Technologies). The analytical column
was an Agilent ZORBAX Eclipse XDB-C8 (4.6 × 150 mm, 5 µm
particle size). The mobile phase consisted of acetonitrile/water (50/
50 v/v), both containing 0.1% trifluoroacetic acid, at a constant
flow-rate of 1.0 mL/min. The injection volume was 20 µL
(Rheodyne, Cotati, CA). The column effluent was monitored at
226 and 250 nm. Quantitative analysis was performed by com-
parison of peak areas with standards chromatographed under the
same conditions. The hydrolysis of all compounds followed first-
3
ONO2), 3.10 (s, 3H, CH3), 4.15 (t, 2H, JHH ) 5.8 Hz), 4.70 (t,
2H, 3JHH ) 6.1 Hz) (CH2CH2CH2ONO2), 6.86-7.00 (m, 3H, C6H3),
7.34 (d, 2H, C6H4), 7.65 (s, 1H, CH Im), 7.99 (d, 2H, C6H4); 13C
NMR (CDCl3) δ: 26.9, 44.4, 65.0, 69.6, 114.8, 117.5, 117.8, 120.0,
120.1, 125.7, 126.1, 129.2, 130.1, 135.6, 140.4, 140.5, 146.8, 147.0,
150.5, 153.8; MS (EI) 469/471 (M)+. Anal. (C19H17ClFN3O6S) C,
H, N.
3-{4-[4-Chloro-1-(4-(methylsulfonyl)phenyl)-1H-imidazol-5-
yl]-2-fluorophenoxy}propan-1-ol (14a). The product was synthe-
sized starting from 10 following a procedure similar to that used
to prepare 11a. The product was purified by flash chromatography
(eluent CH2Cl2/MeOH 98/2 v/v) to give the title compound as a
colorless foam. Yield 75%. 1H NMR (CDCl3) δ: 2.09 (m, 2H, CH2-
order kinetics. The observed pseudo-first-order rate constants (kobs
)
3
for the hydrolysis were calculated from the slopes of linear plots
of the natural logarithm of percent remaining nitrates against time;
the corresponding half-lives (t1/2) were obtained according to the
equation t1/2 ) 0.693/kobs. Structural information of investigated
compounds and relative MS spectra were acquired by LC/MS
technique, using a HP1100 chromatograph system (Agilent Tech-
nologies, Palo Alto, CA) equipped with a binary pump and coupled
with an API 3200 triple-quadrupole spectrometer (Applied Bio-
systems), operating in ESI (electrospray ionization) mode. An
Agilent Zorbax Eclipse XDB-C8 column (4.6 × 150 mm, 5 µm
particle size) was employed; the mobile phase consisted of
acetonitrile/water (70/30 v/v), both containing 0.1% trifluoroacetic
acid, at a constant flow-rate of 400 µL/min. The ion source operated
in positive ion mode at 300 °C with spray voltage at 5000 V, and
positive ions were acquired in the multiple reaction monitoring
(MRM) mode. A 10 µL volume of each solution (100 µM
concentration) was injected, and all separations were performed at
room temperature. The substance-specific voltages (DP-declustering
potential, EP-entrance potential, CXP-cell exit potential, and CE-
collision energy) were optimized for each compound, using standard
solutions at the concentration of 1 ppm.
COX Inhibition. A whole blood assay22,17b was performed to
evaluate the ability of synthesized compounds to inhibit COX-1
and COX-2 isozymes. Blood samples were obtained from healthy
volunteers who had not taken any drug for at last two weeks.
Volunteers, who were treated according to the Helsinki protocol
for biomedical experimentation, gave their informed consent to the
use of blood samples for research purposes. Blood samples were
divided in two aliquots to test COX-1 and COX-2 inhibition. COX-2
aliquot was treated with sodium heparin (10 IU/mL), acetylsalicylic
acid (10 µg/mL) to suppress prostanoid production from COX-1,
and lipopolysaccaride from E. coli (LPS, 10 µg/mL). Methanolic
solutions of the tested compounds at different concentrations were
prepared, 10 µL aliquots were distributed in incubation tubes, and
the solvent was evaporated. The residues were dissolved by
vortexing either in heparinized blood (1 mL) to test COX-2
inhibition or in untreated blood (1 mL) to test COX-1 inhibition.
COX-1 samples were incubated in glass tubes for 1 h at 37 °C and
then were centrifuged at 2000g for 10 min, and serum was tested
for platelet TxB2 production. COX-2 samples were incubated in
polyethylene tubes for 24 h at 37 °C to allow COX-2 expression
in monocytes and maximal PGE2 production. Samples were then
centrifuged at 2000g for 10 min, and plasma was tested for PGE2
production; basal PGE2 production in blood untreated with LPS
was subtracted from all samples. Prostanoid production was
evaluated by enzyme immunoassay (Cayman Chemical). The
percent inhibition in TxB2 (COX-1) and PGE2 (COX-2) production
in compound-treated samples were calculated by comparison with
control untreated samples. The concentration of the tested com-
pounds causing 50% inhibition (IC50) was calculated from the
concentration-inhibition response curve (five to six experiments).
Vasodilator Activity. Thoracic aortas were isolated from male
Wistar rats weighing 180-200 g. As few animals as possible were
used. The purposes and the protocols of our studies were approved
by Ministero della Salute, Rome, Italy. The endothelium was
CH2OH), 3.10 (s, 3H, CH3), 3.89 (t, 2H, JHH ) 5.7 Hz), 4.21 (t,
2H, 3JHH ) 6.0 Hz) (CH2CH2CH2OH), 6.85-6.98 (m, 3H, C6H3),
7.31-7.35 (m, 2H, C6H4), 7.65 (s, 1H, CH Im), 7.98-8.01 (m,
2H, C6H4); 13C NMR (CDCl3) δ: 31.8, 44.5, 60.0, 66.9, 114.5,
117.3, 117.6, 119.5, 119.6, 125.7, 125.8, 129.3, 130.1, 135.5, 140.5,
147.3, 147.4, 150.5, 153.8; MS (EI) 424/426 (M)+. Anal. (C19H18-
ClFN2O4S‚0.75H2O) C, H, N.
5-[4-(Allyloxy)-3-fluorophenyl]-4-chloro-1-[4-(methylsulfonyl)-
phenyl]-1H-imidazole (15). To a stirred suspension of 10 (1.00 g,
2.73 mmol) in dry THF (25 mL), kept under nitrogen, was added
60% NaH (0.12 g, 2.88 mmol). After 15 min, allyl bromide (0.3
mL, 3.46 mmol) was added, and the reaction mixture was heated
at 70 °C overnight. Then, an additional amount of 60% NaH (0.03
g) and allyl bromide (0.1 mL) was added, and the heating was
continued an additional 8 h. After this time, the reaction mixture
was poured into 0.1 N NaOH (50 mL) and extracted with EtOAc.
The organic layer was washed with brine and dried, and evaporated
under reduced pressure. The residue was recrystallized from MeOH
to give the title compound as a yellow solid. Yield 88%. Mp 156-
157 °C (MeOH); 1H NMR (DMSO-d6) δ: 3.27 (s, 3H, CH3), 4.64-
4.66 (m, 2H, OCH2), 5.27-5.44 (m, 2H, CHdCH2), 5.99-6.05
(m, 1H, CH)CH2), 6.95-7.22 (m, 3H, C6H3), 7.53 (d, 2H, C6H4),
8.01 (d, 2H, C6H4), 8.14 (s, 1H, CH Im); 13C NMR (CDCl3) δ:
43.1, 69.1, 115.1, 117.2, 117.4, 118.2, 119.4, 119.5, 125.2, 126.1,
126.4, 126.5, 128.1, 128.3, 132.8, 136.7, 136.9, 139.6, 140.3, 146.1,
146.2, 149.4, 152.6; MS (EI) 406/408 (M)+. Anal. (C19H16-
ClFN2O3S) C, H, N.
3-{4-[4-Chloro-1-(4-(methylsulfonyl)phenyl)-1H-imidazol-5-
yl]-2-fluorophenoxy}propane-1,2-diyl Dinitrate (16). To an ice-
cooled, stirred solution of 15 (0.44 g, 1.08 mmol) and AgNO3 (0.75
g, 4.41 mmol) in acetonitrile (25 mL), was added iodine (0.28 g,
1.08 mmol). After iodine had dissolved, the reaction mixture was
refluxed for 5 days, filtered, poured into water, and extracted with
EtOAc. The organic layer was washed with brine, dried, and
evaporated. The oil thus obtained was purified by flash chroma-
tography (eluent PE/EtOAc 4/6 v/v). Recrystallization from EtOH
afforded the title compound as beige plate-like crystals. Yield 52%.
1
Mp 144.5-145.5 °C (EtOH). H NMR (CDCl3) δ: 3.10 (s, 3H,
CH3), 4.34-4.36 (m, 2H, OCH2), 4.77-4.84 (m, 1H), 4.93-4.98
(m, 1H) (CH-CHaCHbONO2), 5.61-6.64 (m, 1H, CHONO2),
6.87-7.03 (m, 3H, C6H3), 7.33 (d, 2H, C6H4), 7.65 (s, 1H, CH
Im), 7.99 (d, 2H, C6H4); 13C NMR (CDCl3) δ: 44.4, 66.4, 68.5,
116.0, 117.9, 118.2, 121.6, 121.7, 125.3, 125.7, 126.1, 129.3, 130.4,
135.8, 140.3, 140.6, 145.8, 145.9, 150.7, 154.0; MS (CI) 531/533
(M + 1)+. Anal. (C19H16ClFN4O9S) C, H, N.
Evaluation of Stability in Human Serum and Whole Blood.
Compounds 8, 9, 11, 14, 16 were incubated for 24 h at 100 µM
concentration both in human serum (Aldrich) and in heparinized
human blood. Resulting solutions were maintained at 37 ( 0.5 °C
and at appropriate time intervals aliquots were diluted 1:2 with
acetonitrile containing 0.1% trifluoroacetic acid in order to depro-
teinize and precipitate cells, proteins, and enzymes. Samples were
sonicated, vortexed, and then centrifuged for 15 min at 2150g. The
clear supernatant was filtered by 0.45 µm PTFE filters (Alltech)
and analyzed by RP-HPLC, in order to accomplish separation and

1456 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 7
ChegaeV et al.
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removed, and the vessels were helically cut: three strips were
obtained from each aorta. The tissues were mounted under 1.0 g
tension in organ baths containing 30 mL of Krebs-bicarbonate buffer
with the following composition (mM): NaCl 111.2, KCl 5.0, CaCl2
2.5, MgSO4 1.2, KH2PO4 1.0, NaHCO3 12.0, glucose 11.1,
maintained at 37 °C and gassed with 95% O2-5% CO2 (pH )
7.4). The aortic strips were allowed to equilibrate for 120 min and
then contracted with 1 µM L-phenylephrine. When the response to
the agonist reached a plateau, cumulative concentrations of the
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vasodilating agent were added. Results are expressed as EC50
(
SE (µM). The effects of 1 µM ODQ and 10 µM oxyhemoglobin
on relaxation were evaluated in separate series of experiments. In
the first case ODQ was added to the organ bath 5 min before the
contraction, while in the second case HbO2 was added before
contraction plateaued. Responses were recorded by an isometric
transducer connected to the MacLab System PowerLab. Addition
of the drug vehicle (DMSO) had no appreciable effect on contrac-
tion level.
Preparation of Oxyhemoglobin. Bovine hemoglobin type 1 (H-
2500 Sigma Chemical Co.) contains a mixture of oxyhemoglobin
and its oxidized derivative methemoglobin. Pure oxyhemoglobin
was prepared by adding a solution of commercially available
hemoglobin in 50 mM phosphate saline buffer, pH 7.4, to an excess
of the reducing agent sodium dithionite (Na2S2O4) at 4 °C and was
then protected from the light. Hemoglobin (64.5 mg) was gently
dissolved into distilled water (1 mL); sodium dithionite (53.6 mg)
was then added to the solution which was loaded onto a chromato-
graphic column (Sephadex G-25, Pharmacia, Uppsala, Sweden) and
eluted with phosphate buffer. Two Pasteur pipets were used as
columns for 1 mL of this solution. The purity of the oxyhemoglobin
solution was determined spectrophotometrically (600-360 nm; λmax
) 414 nm, ꢀ ) 1.25 × 105) by diluting the eluted solution 1:600
with buffer. The solutions were freshly prepared daily.
Molecular Modeling. All COX-2 inhibitors used in the simula-
tions were constructed using standard bond lengths and angles with
the MOE modeling suite.29 All quantum mechanical calculations
were performed with the GAMESS-US software package.30 The
crystal structures of COX-2 and COX-1 EI complexes were
downloaded from the Brookhaven Protein Data Bank31 (entry codes
1cx2 and 1q4g). Docking was performed with the Lamarckian
Genetic Algorithm (LGA) implemented in AutoDock 3.0.5.23 EI
complexes setup and refinement as well as MM-GBSA simulations
were performed with the AMBER 8 software package.32 All
calculations were performed on a Beowulf-type 8-CPU Linux
cluster (4 Intel Pentium IV 2.4-3.0 GHz - 4 AMD Athlon XP
1.8-2.4 GHz).
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applications of nitric-oxide releasing non-steroidal anti-inflammatory
and related nitric oxide-donating drugs. Br. J. Pharmacol. 2002, 137,
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cancer prevention. Trends Mol. Med. 2004, 10, 324-330.
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Characterisation of isomeric glycerol dinitrates. J. Chem. Soc. 1965,
1319-1324.
(21) Testa, B.; Mayer, J. Hydrolysis in Drug and Prodrug Metabolism;
Wiley-VCH: Weinheim, 2003; pp 534-590.
Acknowledgment. This work was supported by a MIUR
grant (COFIN 2005). Part of the molecular modeling work was
carried out by P.T. at the LCT - Pharmacochimie Laboratory
of the University of Gene`ve. The authors are indebted to Dr.
Daniele Di Corcia and Dr. Veronica Morra (Centro Regionale
Antidoping “Alessandro Bertinaria”) for LC/MS studies.
(22) Patrignani, P.; Panara, M. R.; Greco, A.; Fusco, O.; Natoli, C.;
Iacobelli, S.; Cipolline, F.; Ganci, A.; Cre´minon, C.; Maclouf, J.;
Patrono, C. Biochemical and pharmacological characterization of the
cyclooxygenase activity of human blood prostaglandin endoperoxide
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and detailed computational procedures. This material is available
free of charge via the Internet at http://pubs.acs.org.
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