Cyclooxygenase-1-selective inhibitors based on the (E)-2′- des -methyl-sulindac sulfide scaffold

Article abstract of DOI:10.1021/jm201528b

Prostaglandins (PGs) are powerful lipid mediators in many physiological and pathophysiological responses. They are produced by oxidation of arachidonic acid (AA) by cyclooxygenases (COX-1 and COX-2) followed by metabolism of endoperoxide intermediates by terminal PG synthases. PG biosynthesis is inhibited by nonsteroidal anti-inflammatory drugs (NSAIDs). Specific inhibition of COX-2 has been extensively investigated, but relatively few COX-1-selective inhibitors have been described. Recent reports of a possible contribution of COX-1 in analgesia, neuroinflammation, or carcinogenesis suggest that COX-1 is a potential therapeutic target. We designed, synthesized, and evaluated a series of (E)-2′-des-methyl-sulindac sulfide (E-DMSS) analogues for inhibition of COX-1. Several potent and selective inhibitors were discovered, and the most promising compounds were active against COX-1 in intact ovarian carcinoma cells (OVCAR-3). The compounds inhibited tumor cell proliferation but only at concentrations >100-fold higher than the concentrations that inhibit COX-1 activity. E-DMSS analogues may be useful probes of COX-1 biology in vivo and promising leads for COX-1-targeted therapeutic agents.

Full text of DOI:10.1021/jm201528b

Article
pubs.acs.org/jmc
Cyclooxygenase-1-Selective Inhibitors Based on the (E)-2′-Des-
methyl-sulindac Sulfide Scaffold
Andy J. Liedtke, Brenda C. Crews, Cristina M. Daniel, Anna L. Blobaum, Philip J. Kingsley,
Kebreab Ghebreselasie, and Lawrence J. Marnett*
A. B. Hancock Jr. Memorial Laboratory for Cancer Research, Departments of Biochemistry, Chemistry and Pharmacology, Vanderbilt
Institute of Chemical Biology, Center in Molecular Toxicology and Vanderbilt-Ingram Cancer Center, Vanderbilt University School
of Medicine, Nashville, Tennessee 37232, United States
S
* Supporting Information
ABSTRACT: Prostaglandins (PGs) are powerful lipid mediators
in many physiological and pathophysiological responses. They are
produced by oxidation of arachidonic acid (AA) by cyclo-
oxygenases (COX-1 and COX-2) followed by metabolism of
endoperoxide intermediates by terminal PG synthases. PG
biosynthesis is inhibited by nonsteroidal anti-inflammatory drugs
(NSAIDs). Specific inhibition of COX-2 has been extensively
investigated, but relatively few COX-1-selective inhibitors have
been described. Recent reports of a possible contribution of COX-
1 in analgesia, neuroinflammation, or carcinogenesis suggest that
COX-1 is a potential therapeutic target. We designed, synthesized,
and evaluated a series of (E)-2′-des-methyl-sulindac sulfide (E-DMSS) analogues for inhibition of COX-1. Several potent and
selective inhibitors were discovered, and the most promising compounds were active against COX-1 in intact ovarian carcinoma
cells (OVCAR-3). The compounds inhibited tumor cell proliferation but only at concentrations >100-fold higher than the
concentrations that inhibit COX-1 activity. E-DMSS analogues may be useful probes of COX-1 biology in vivo and promising
leads for COX-1-targeted therapeutic agents.
The “COX-2” hypothesis posited that COX-1 inhibition is
responsible for the gastrointestinal toxicity of NSAIDs.
However, animal studies suggest that the total extent of COX
inhibition is more important than the inhibition of the
individual enzymes and that highly selective COX-1 inhibitors
do not exhibit gastrointestinal toxicity analogous to highly
selective COX-2 inhibitors.24,25 COX-1-dependent prostaglan-
din synthesis has been implicated in many pathophysiological
processes including atherosclerosis, endothelial dysfunction,
neuroinflammation, preterm labor, pain, and cancer.26,27 The
role of COX-1 in neurodegenerative diseases is of particular
interest. Neurodegenerative disorders that exhibit a strong
inflammatory component produce prostaglandins (PGs) in
neurons and glial cells.28 The extent of neurodegeneration is
reduced in COX-1 knockout mice or by administration of
COX-1-selective inhibitors.29−31 Very recent results indicate
that COX-1 is a major source of pro-inflammatory PGs in the
brains of both LPS-treated mice and mice treated with the
Parkinsonism-inducing compound, 1-methyl-4-phenyl-1,2,3,6-
tetrahydropyridine.32 Therefore, COX-1-selective inhibitors
represent a potentially useful class of drugs that has not been
extensively investigated.
INTRODUCTION
■
Cyclooxygenases (COX-1 and COX-2) catalyze the oxygen-
ation of arachidonic acid (AA) to form prostaglandins and
thromboxane, which mediate a range of physiological and
pathophysiological responses.1 The discovery in 1971 that
nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit pros-
taglandin synthesis in guinea pig lung and human platelets
established COX-1 as a molecular target for this ancient class of
drugs.2−4 The subsequent discovery in 1991 of COX-2, which
is induced by cytokines during inflammation, suggested that
this form of the enzyme represents the molecular target for the
anti-inflammatory effects of NSAIDs.5−8 The differential
expression of COX-1 and COX-2, and in particular the finding
that COX-1 is the principal form expressed in the gastro-
intestinal tract, led to the search for COX-2-selective inhibitors
as potential anti-inflammatory agents that might lack the
gastrointestinal side effects of traditional NSAIDs.9−11
A
number of highly selective inhibitors were introduced to the
market including celecoxib (6), rofecoxib (7), valdecoxib,
etoricoxib, and lumiracoxib (Figure 1).12−17 These compounds
exhibited reduced gastrointestinal side effects in human testing
but did not completely eliminate this liability.18,19 In addition,
long-term placebo-controlled studies revealed cardiovascular
side effects that led to the withdrawal of rofecoxib and
valdecoxib from the market in the United States and
Europe.20−23
Received: November 11, 2011
Published: January 20, 2012
© 2012 American Chemical Society
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Figure 1. Upper row: the structures of sulindac (sulfoxide, 1a), its in vivo metabolites (1b and 1c), and 2′-des-methyl sulindac sulfide (2) as well as
indomethacin (3, nonselective COX-1/-2 inhibitor). Lower row: N-(5-amino-2-pyridinyl)-4-(trifluoromethyl) benzamide (TFAP, 4), SC-560 (5)
(selective COX-1 inhibitors), celecoxib (6), and rofecoxib (7) (selective COX-2 inhibitors).
The COX-1 inhibitors that have been described in the
literature fall into two main structural classes.26 One class
comprises diarylheterocycles discovered during the COX-2
inhibitor programs that led to the development of 6 and 7
(Figure 1). Noteworthy among this class of inhibitors is SC-560
(5, Figure 1), which exhibits COX-1 selectivity greater than
700-fold and which has been extensively used as an in vitro and
in vivo probe, for example, for investigating inhibition of PGE2
synthesis in rat primary spinal cord neurons or in (mouse)
models of human ovarian cancer (OVCAR-3).33−36 The other
class of COX-1 inhibitors comprises substituted benzamides
related to N-(5-amino-2-pyridinyl)-4-(trifluoromethyl)-benza-
mide (TFAP, 4; Figure 1).25,37 This compound exhibits high
COX-1 selectivity but has not been used extensively as a probe.
TFAP and its analogues have been suggested as candidates for
analgesics that do not cause stomach erosions or ulcers.25
Other compounds related to resveratrol, a noncompetitive
COX inhibitor with anti-inflammatory, cardiovascular protec-
tive, and cancer chemopreventive properties, and curcumin, the
active component of turmeric that possesses anti-inflammatory
and anticancer activity, are reported to exhibit modest COX-1
selectivity. A recent study of 92 stilbene analogues, whose
biological activities were assessed with various chemopreven-
tion targets, revealed a handful of nitro- or amino-substituted
resveratrol derivatives that inhibit COX-1 with potency roughly
comparable to the parent compound but without affecting
COX-2.39 Finally, valeryl salicylate, a derivative of aspirin,
selectively inhibits COX-1 by covalent modification of an active
site serine residue.26,38 Biological effects of valeryl salicylate
have been, for example, studied in models of acute
inflammation in mice.39
Sulindac (compound 1a, Figure 1) is an NSAID that exhibits
cancer chemopreventive activity in animal models, induces
polyp regression in familial polyposis patients, and inhibits
polyp recurrence in patients when combined with α-
difluoromethylornithine.40−46 Sulindac is a pro-drug that is
reduced to the active sulfide metabolite by colonic microflora.47
Sulindac sulfide (compound 1b, Figure 1) is a slow, tight-
binding inhibitor of both COX-1 and COX-2. We recently
reported that the 2′-des-methyl derivative of 1b (compound 2,
Figure 1) does not inhibit COX-2 but selectively inhibits COX-
1 (Table 1 and Figure S5 in the Supporting Information).48
The absence of the 2′-methyl group during indene synthesis
quantitatively directs the geometry of the introduced
benzylidene double bond to (E) rather than (Z), which is
formed when the 2′-methyl group is present;49 compound 2 is a
rapid, reversible inhibitor of COX-1. The novelty of this
scaffold prompted us to investigate its potential for the
construction of more potent and selective COX-1 inhibitors.
In the present manuscript, we describe the synthesis of a
series of compounds designed to probe the importance of the
various functionalities in 2 with regard to selective inhibition of
COX-1. We find that modification of the benzylidene group
leads to improved inhibitors, but alterations in the 5′-fluoro or
carboxyl group are less well tolerated. The most active
compounds are potent inhibitors of COX-1 in cultured
human ovarian cells but are weak inhibitors of the growth of
the cells in vitro.
RESULTS
■
The indene template is a widely used pharmacophore that has
found many applications in medicinal chemistry, for example, in
NSAIDs.50−53 Recent reports have indicated that the
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Table 1. COX-1 and COX-2 Inhibition by Arylmethylidene Variants of E-DMSS*
*
a
Compounds were screened at 4 μM. A concentration of 5 μM of AA-substrate was employed; n.d., not determined. Mean SEM of two (n)
experiments.
benzylidene-indene acetic acid derivative 1b can be structurally
re-engineered to improve isoform-specific COX binding inter
alia.43,54,55 In the present study, compound 2, the E-2′-des-
methyl-sulindac sulfide [(E)-DMSS] analogue of 1b, served as
the lead scaffold for construction of potential COX-1-selective
inhibitors. Modifications were made at the carboxyl, benzyli-
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Figure 2. Intended chemical modifications on 2 and 13.
Scheme 1. General Synthetic Route to Multisubstituted (E)-2′-Des-methyl Sulindac Sulfide Analogues Including Procedures for
a
Ester Cleavage and (Re)Esterification Reactions
a
Reagents and conditions: (a) For compound 2: ethyl bromoacetate, activated zinc dust, benzene/ether, reflux, 16 h. (b) 2 M LDA, THF,
(substituted) ethyl alkanoate, −75 °C, 2 h. (c) TsOH·2H2O, CaCl2·2H2O, toluene, reflux, overnight. (d) 1 N NaOH, MeOH, 65−70 °C. (e)
Potassium trimethylsilanoate (90% material), THF, microwave radiation, 90−120 °C, 15 min. (f) Water, 2−4 M HCl. (g) 1 M LiOH, THF, RT, 5−6
h. (h) Alkyl alcohol, H2SO4, reflux, overnight.
dene, and 5′-position of the indene ring (Figure 2). The
synthetic scheme followed the general approaches previously
described for assembly of sulindac analogues with some
modifications (Scheme 1).53,56 In contrast to the standard
procedures, which employ “activated” zinc and expensive α-
haloalkanoyl esters, we reacted the indanone precursors, 8, with
inexpensive ethyl alkanoates at low temperatures using lithium
diisopropylamide in tetrahydrofuran.57 This method generated
the intermediate alcohols, 9, after an acidic quench in a much
shorter time (2 h). The quantities of side products detected by
HPLC were less than with the lengthy Reformatsky reaction
(overnight with Zn0 catalyst).58 The applied alkylation reaction
tolerated different substituents at the core aromatic annulus
(e.g., 6′-F, 6′-OCH3) and allowed the introduction of α-
unsubstituted (9a,b), monomethylated (9c), or geminal-
dimethylated (9d) carboxymethyl moieties at position 1 of
the indanone ring. Compounds 9a, 9c, and 9d hold a 6′-F
substituent at the 1-hydroxy-2,3-dihydro-1H-inden-1-yl partial
structure, whereas 9b has a methoxy group at its 6′-position.
HPLC analysis of 9a, 9b, and 9d, which contain a single
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asymmetric carbon, afforded a single peak, whereas compound
9c, which has two chiral centers, afforded two substantial peaks
due to the presence of diastereomers. Attempts to prepare a
cyclopropyl analogue using ethyl cyclopropanecarboxylate as an
alkylation reagent failed due to the instability of the
intermediate cycloalkyl carbanion.59,60
substituents exhibited modest COX-1 selectivity (11f−m).
Substitution of carboxyl at the para position reduced the
potency against COX-1 but more substantially reduced
inhibition of COX-2. Conversion of the phenyl ring to a
naphthyl or aza-naphthyl ring maintained COX-1 selectivity
and in some cases increased it (12d and 12f). The most potent
and selective COX-1 inhibitor in this series was the biphenyl
analogue 13a (COX-1 IC50, 570 nM; COX-2 IC50, > 4 μM).
Such hydrophobic biphenyl systems are a common structure
template seen in other small molecule inhibitors of the AA
pathway (e.g., flurbiprofen [NSAID] or MK-866 analogues
[microsomal prostaglandin E2 synthase-1 (mPGES-1) inhib-
itors]).60,62 Concentration dependences were determined for
the most potent compounds, which led to the determination of
IC50 values for a subset of the inhibitors (Table 1 and Figure S5
and Table S4 in the Supporting Information).
Dehydration of 9a and 9b produced a mixure of exo- and
endo-olefins for both 10a and 10b (Table S1 in the Supporting
Information).50,57 Steric hindrance from the exocyclic alkyl
chain of the racemic mixture 10c favored conversion to the
endo-olefin as indicated by HPLC analysis and by comparison
to the UV spectrum of 10d, which cannot exist in the exo-form
(Table S1 in the Supporting Information). Unseparated
isomeric mixtures of ethyl esters, 10a−c, were employed in
the subsequent condensation step. Knoevenagel (aldol)
condensation between 10a−d and the appropriate aldehydes
proceeded under basic conditions to afford a single endo-olefin
in all cases. Considerable amounts of byproduct, most likely
from the Cannizzaro reaction, could be detected by HPLC, MS,
and NMR. Together with the recognized light instability of the
E-DMSS analogues (UV-induced isomerization about the
exocyclic double bond from E to Z), this complicated the
purification process and decreased the isolatable yields for some
compounds.48,50,61 The basic conditions of the condensation
led to ester hydrolysis for compounds derived from 10a and
10b. In addition, the lipophilic nature of the final E-DMSS
analogues occasionally allowed their quantitative isolation as
pure sodium salts directly from the aqueous-alkaline mother
liquor (Table S2 in the Supporting Information). The acids
could be esterified with alcohols under acidic conditions and
hydrolyzed with LiOH.55 Hydrolysis was not observed for
compounds derived from 10c and 10d. The ester products
either crystallized from the reaction mixture or were extracted
and purified by chromatography. The stereochemistry of the
exocyclic double bond of all of the E-DMSS analogues was E as
anticipated by the absence of a methyl group at the 2′-position
To build on the discovery of 13a, a series of substituted
biphenyls were synthesized by either Knoevenagel condensa-
tion or Suzuki−Miyaura coupling of brominated benzylidene
precursors with (hetero)aryl boronic acids (e.g., 13f and 13k;
Scheme 2 and Figure S1 in the Supporting Information).63
Scheme 2. Synthesis of New “Biphenyl Derivatives” of 2′-
Des-methyl Sulindac Sulfide Using Suzuki−Miyaura
a
Coupling Reactions
a
Reagents and conditions: Pd(PPh3)4, K+-carbonate, DME/H20, 90
1
°C, 14 h. Suzuki−Miyaura couplings were performed on submillimolar
of the indenyl ring (compare H NMR and NOESY spectrum
scale in a sealed glass tube under argon.63
of 20b in Figures S2 and S3 in the Supporting Information).48
Detailed experimental conditions and spectral properties of all
intermediate and final compounds are provided in the
Supporting Information.
Evaluation of this series (Table 2) indicated that multiple
substitutions were tolerated, although none dramatically
increased either the potency or the selectivity of COX-1
inhibition over compound 13a. Interestingly, introduction of a
2-aza substituent into a meta-substituted biphenyl scaffold
reversed the selectivity of inhibition, yielding compounds with
modest COX-2 selectivity (17a−e; compare Figure S6 in the
Supporting Information).
Neutralization of the carboxylic acid by conversion to an
ester or amide in the benzylidene series reduced potency but
maintained selectivity for COX-1, except for the biphenyl
methylidene analogue 16e, which revealed potent anti-COX-1
activity but also increased COX-2 inhibition (Table 3). No
significant differences were observed on changing the ester
from methyl to isopropyl (16a−c).64
Substitution α- to the carboxyl was explored by synthesis of a
series of esters and acids (Table 4). The general route outlined
in Scheme 1 was employed using ethyl esters of the indene
acetic acids, 10c and 10d, as building blocks. It was not possible
to make a complete series of monomethyl-substituted
analogues because of low yields and the generation of multiple
side products (Scheme S1 in the Supporting Information). The
only monomethyl analogue prepared was the ethyl ester, 18a
(Table 4), which demonstrated reduced COX-1 inhibitory
Individual compounds were preincubated with purified ovine
COX-1 or murine COX-2 for 17 min followed by addition of
[1-14C]-AA (Figure S4 in the Supporting Information:
experimental timeline). After 3 min, the reaction was quenched,
and radioactive products were extracted and quantified as
described in Supporting Information. For initial screening, a
single concentration of 4 μM inhibitor was employed, and the
concentration of [1-14C]-AA was 5 μM. The 4 μM inhibitor
concentration was chosen based on the previously determined
IC50 of 1.8 μM for compound 2. The AA concentration of 5
μM represents the Km for COX-1 and COX-2, which enables
rapid, reversible, and slow, tight-binding inhibitors to be
detected. Compound 2 was used as a reference for all new E-
DMSS analogues.
Table 1 lists the percent inhibition of COX for the initial
series of arylmethylidene analogues of 2.51 We determined the
effects of different steric and electronic properties upon COX-1
and COX-2 inactivation. Oxidation of the sulfide (11a and
11b) reduces activity as previously reported for sulindac sulfide
analogues. Substitution with trifluoromethylsulfide (11c)
maintains some COX-1 selectivity, while oxidation of the
sulfur again reduces activity (11d and 11e). A range of para
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Table 2. continued
Table 2. COX-1 and COX-2 Inhibition by Substituted
Biphenylmethylidene Derivatives of E-DMSS*
*
Compounds were screened at 4 μM. A concentration of 5 μM of AA-
a
substrate was employed. Mean SEM of two (n) experiments.
Table 3. COX-1 and COX-2 Inhibition by Ester and Amide
Derivatives of E-DMSS*
*
Compounds were screened at 4 μM. A concentration of 5 μM of AA-
a
substrate was employed. Mean SEM of two (n) experiments.
activity (30% inhibition at 4 μM) as compared to the ethyl ester
of the unsubstituted biphenyl methylidene compound, 16e
(COX-1 IC50, 1.1 μM) (Table 3 and Figure 7).65 Dimethyl
analogues were prepared in high yield with minimal side
products. The steric hindrance introduced by α,α-disubstitu-
tions dramatically reduced the ease of hydrolysis to the acids.
Thus, a nonaqueous hydrolytic strategy was employed in which
THF solutions of individual esters were heated in a microwave
with potassium trimethylsilanoate (Scheme 1).66 This afforded
nearly quantitative conversion of the esters to the acids. The
two initially prepared acids, 19a and 19c, were less active than
the unsubstituted free acids, 2 and 13a (Table 1), so no further
acids were synthesized. The ethyl esters of the α,α-disubstituted
compounds, 19b and 19d−20b (Table 4) retained COX-1
selectivity but exhibited reduced potency. The most selective
inhibitor was the oxazole, 19i.
A series of substituted alkyl- and arylsulfonimides as
carboxylic acid isosteres were synthesized as depicted in
Scheme 3.60,67,68 Bioisosteric replacements represent a
common approach for the rational modification of lead
compounds into safer and more clinically effective agents
with similar biological properties to the parent compound.
Moderate COX-1 selectivity was observed for compounds 21a,
21b, and 21d−n (Table 5), but the trifluoromethylsulfonimide,
21c, with biphenylmethylidene substituent, was the most
potent and selective compared of all of the analogues
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Substitution of methoxy for fluoro at the indene 5′-position
in analogues 15a and 15b, respectively (like in compound 3),
led to a substantial loss of inhibitory potency for both the
phenylmethylsulfide and the biphenyl derivatives (Figure 3 and
Table S3 in the Supporting Information).69 The differential was
most dramatic for the phenylmethylsulfide derivative, 15a,
which was a poor COX-1 inhibitor. The 5′-methoxy derivative
of the biphenyl, 15b, exhibited modest COX-1 inhibitory
activity, although the presence of a plateau at higher inhibitor
concentrations suggests that inhibition is readily reversible (also
see Figures S7 and S8 in the Supporting Information).49
The ability of the various des-methylsulindac sulfide
analogues to inhibit COX-1 activity in intact cells was evaluated
using the human ovarian cancer cell line, NIH-OVCAR-3.35,36
This cell line expresses high levels of COX-1 but no detectable
COX-2 as demonstrated by the Western blot in Figure 4a.36
Individual compounds were incubated with the cells for 30 min
followed by the addition of [1-14C]-AA and another 30 min
incubation. Compound 2, 13a, and 21c inhibited COX-1-
dependent [1-14C]-AA oxidation with potencies comparable to
that of the known COX-1 inhibitor, SC-560 (compound 5).33
Minimal inhibition of COX-1 in OVCAR-3 cells was detected
with celecoxib (compound 6) (Figure 4a). When parallel
experiments were conducted in the COX-2 expressing human
head and neck cancer cell line, 1483, no inhibition of [1-14C]-
AA oxygenation was observed by 2 and 13a, whereas 6 potently
inhibited oxygenation (IC50 = 54 nM) (Figure 4b).
Table 4. COX-1 and COX-2 Inhibition by α-Substituted E-
DMSS Analogues*
Sulindac (compound 1a) and sulindac sulfide (compound
1b) inhibit the growth of tumor cells in culture, and there has
been some controversy about the role of COX inhibition
(especially COX-2 inhibition) in this antiproliferative activ-
ity.43,70−75 Therefore, we evaluated the effect of 2, 13a, 1b, and
1a on the viability of OVCAR-3 cells (Figure 5 and Supporting
Information).76 Following a 2 day treatment, comparable EC50
values for inhibition of cell growth were observed with 2 (223
μM), 13a (132 μM), and 1a (210 μM), but no inhibition was
observed with 1b up to 250 μM. Comparison of Figures 4a and
5 reveals that inhibition of cell growth requires concentrations
of 2 and 13a that are more than 100-fold higher than the
concentrations required for inhibition of COX-1 activity in the
OVCAR-3 cells. Therefore, it appears that the antiproliferative
effects of this series of compounds on OVCAR-3 cells grown in
culture are independent of their ability to inhibit COX-1
activity. Evaluation of sulindac sulfide and compounds 13a and
21b in the breast cancer cell line, MDA-MB231, yielded EC50
values of 209, 141, and 215 μM (Figure S11 in the Supporting
Information).
DISCUSSION
■
Figure 6 summarizes the structure−activity relationships
(SARs) for the series of compounds evaluated in the present
study. Increasing the size and hydrophobicity of the aryl group
from methylsulfanylbenzylidene to biphenylmethylidene sig-
nificantly improved the potency and selectivity of COX-1
inhibition, so a number of analogues were made (Figure 7).
Substitutions on the biphenyl ring (e.g., fluoro, trifluoromethyl)
did not increase potency. Introduction of nitrogen into either
biphenyl ring to increase hydrophilicity decreased potency, and
the presence of multiple nitrogens in one ring reduced it
further. Fusing the biphenyl (fluorene) retained potency against
COX-1 but introduced a higher activity against COX-2. Alkyl
substitution α- to the carboxyl group reduced activity in all
cases. Conversion of the carboxylic acid to an ester or amide
*
Compounds were screened at 4 μM. A concentration of 5 μM of AA-
a
substrate was employed. Mean SEM of two (n) experiments.
synthesized in the present study (COX-1 IC50, 470 nM; COX-2
IC50, 14 μM; compare Figure S6 in the Supporting
Information). This meant that it exhibited a more than 4-fold
improvement in activity against COX-1 as compared with our
early lead and reference compound 2. Analogue 21c was
approximately 30-fold more selective for COX-1 over COX-2.
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a
Scheme 3. Preparation of Sulfonimide Derivatives of 2′-Des-methyl Sulindac Sulfide
a
Syntheses were performed on a parallel synthesis apparatus using a straightforward one-pot, two-step CDI carbodiimide coupling reaction (route
A).67 Alternatively, the two-step sulfonamide couplings could be accomplished with oxalyl chloride as the carboxylic acid activator, according to a
disclosed procedure, as established for compound 21c (route B).65,86,87 Reagents and conditions: (Route A): (a1) CDI/DCM, 0−5 °C, 2 h; (b1)
alkyl-/arylsulfonamide, DBU, RT, overnight. (Route B): (a2) oxalyl chloride/DCM, RT, overnight; (b2) alkyl-/arylsulfonamide, 1,2-DCE, pyridine,
RT, overnight.
derivative significantly reduced potency, but introduction of the
sulfonimide isostere in place of the carboxylate generated the
most potent and selective COX-1 inhibitor in the series.
Substitution on the sulfonyl sulfur was tolerated from methyl to
substituted aryl. Perhaps the most surprising result was the
finding of significantly reduced activity on substitution of a 5′-
methoxy for the 5′-fluoro.
The in vitro screen utilized ovine COX-1 and mouse COX-2.
Ovine COX-1 is the closest in sequence to human COX-1
among several mammalian species and is commonly used as a
surrogate for human COX-1.77−79 The human enzyme has
proven difficult to routinely express and purify with high
activity. To verify the in vitro results, we tested the most active
compounds against human COX-1 in cultured human ovarian
cancer cells, OVCAR-3, and against human COX-2 in cultured
head and neck cancer cells, 1483. All of the compounds
inhibited COX-1 in the OVCAR cells to an extent that was
comparable to that of the established COX-1 inhibitor, 5. None
of the compounds inhibited COX-2 in the 1483 cells. In
contrast, 6 potently inhibited COX-2 in the 1483 cells but had
no effect on COX-1 in the OVCAR-3 cells. Thus, the lead
compounds identified in the in vitro screen were effective
inhibitors of human COX-1 in intact cells.
There was a dramatic differential in the ability of the lead
compounds to inhibit PG synthesis by COX-1 in the OVCAR-3
cells and their ability to reduce proliferation in the same cell
type. Whereas complete COX-1 inhibition was observed below
1 μM, none of the E-DMSS analogues reduced proliferation
below 50 μM, and the EC50 values were on the order of 130−
220 μM (Figures S9a,b and S10 in the Supporting
Information). Thus, it appears that the ability of compound
1b and the analogues described herein to inhibit proliferation is
independent of their ability to inhibit COX-1. Because these
experiments were performed in cell culture, one cannot
conclude that COX-1 inhibition would not inhibit tumor
growth in vivo.74,80 Tumor growth and metastasis are complex
processes involving multiple steps, such as angiogenesis,
motility, invasion etc., which are not components of growth
in vitro.36,81 Indeed, literature compound 5 inhibits tumor
growth in different mouse models of ovarian carcinoma.35,82
Thus, E-DMSS analogues may have antitumor activity as well.76
Compound 3 (Figure 1) is a structurally related COX
inhibitor to 1b (and 2) and was used for modeling of COX-1
inhibitor interactions.25 In 3, the p-chlorobenzoyl group at the
indole nitrogen can rotate around the connecting σ-bond. This
allows the molecule to take up an S-trans-conformation, besides
its preferred and lower energy S-cis-conformation, to interact
with COX. Whereas the cis conformer of 3 had been found to
bind to both COX forms, the trans conformer was only present
in cocrystal complexes with COX-1.25 This trans-conformation
of 3 emulates the molecule geometry of the rigid E-2′-DMSS
derivatives described in the present study (see Figure 1).
The nearly identical 3D structures of the two COX isoforms
constitute a substantial obstacle for the design of selective
COX-1 inhibitors.78,83 This is particularly true because in COX-
1, the cavity of the selectivity pocket is less accessible due to the
presence of Ile523. The same cavity is more spacious in COX-2,
having a Val at the same amino acid position.1 It is assumed
that compound 2 and its analogues described herein exert an
atypical binding mode with COX, as the orientation of the p-
methylsulfanylphenyliden group is predicted to cause steric
clashes when the compounds are modeled into a similar
configuration as 1b or 3 in the active site.84 Unfortunately, the
attempt to cocrystallize one of the more potent E-DMSS
analogues (2 or 13a) together with oCOX-1 has not succeeded
thus far.83
There has been a report proposing an optional binding mode
of COX-1-selective inhibitors derived from 3.84 Moreover, a
recent docking study on the COX binding of 2-methyl-3-
indolylacetic acid derivatives that preferentially inactivate COX-
1 suggested that the binding specificity of the reported
compounds resulted from individual plasticities of the 3D
protein structure close to the binding site (“selective induced
fit”).85 These data further point out the formation of a new
lipophilic interaction site by COX-1 structural rearrangements
triggered by the ligand that favors a boost in inhibitory activity
for accurately fitting compounds. The less flexible COX-2
protein does not allow such conformational changes to take
place and thus confines binding affinity.85 This hypothesis
could be taken into consideration to rationalize the benefit of
the rather bulky and lipophilic biphenyl substituent as part of
our optimized COX-1 selective E-DMSS analogues (e.g., 13a or
21c).
COX-1 has emerged as a potential pharmacological target for
the treatment of several clinical conditions, and preclinical and
clinical data suggest that selective COX-1 inhibitors may not
exhibit significant gastrointestinal and cardiovascular side
effects.24,25,56 Thus, the E-DMSS analogues described in the
present report may be useful leads for novel COX-1 inhibitors
or useful probes for the involvement of COX-1 in physiological
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Table 5. COX-1 and COX-2 Inhibition by Sulfonimide
Derivatives of E-DMSS*
Figure 3. Comparison of the inhibition of ovine COX-1 by 15a (black
circle), 15b (red triangle), and 2 (blue square).
EXPERIMENTAL SECTION
■
General. Reagents and solvents were of commercial quality and
were used without further purification. All synthesized intermediates
1
and final compounds were structurally characterized using H NMR
(optionally 19F NMR, 13C NMR) and electrospray ionization mass
spectrometry. The purity of the test compounds was determined using
HPLC [UV detection at 220 and 254 nm (optionally 288 and 347 nm)
along with ELSD detection] and was generally ≥95%, if not denoted
otherwise. The general synthetic procedures A−J are specified in the
Supporting Information.
Preparation and Analytical Characterization of Exemplified
Test Compounds. (E)-2-(5-Fluoro-1-((2-fluorobiphenyl-4-yl)-
methylene)-1H-inden-3-yl)acetic Acid (13d). According to general
procedure C, the title compound was obtained from the isomer
mixture 10a (0.05 g, 0.23 mmol) and 2-fluorobiphenyl-4-
carbaldehyde (0.05 g, 0.25 mmol) after heating to 65 °C for 3 h
and subsequent stirring at ambient temperature overnight. After
acidification of the reaction mixture and repeated extraction
with dichloromethane, the organic layers were combined and
concentrated in vacuo. The remaining yellow solid material
revealed good analytical quality and required no further
purification. Yield, 63 mg (74%): C24H16F2O2, Mr = 374.39.
1H NMR (400 MHz, DMSO-d6) δ: 3.70 (s, 2H), 7.08 (dtd, J =
1.2/2.4/8.4 Hz, 1H), 7.16−7.19 (m, 2H), 7.41−7.45 (m, 1H),
7.49−7.53 (m, 2H), 7.58−7.67 (m, 6H), 7.84 (dd, J = 5.2/8.0
Hz, 1H). HPLC (method 1) tR: 11.30 min (>99%, UV347).
ESI/MS: calcd, 373; found, 373.13 ([M − 1]+, 22%), 329.27
([M − 1]+−CO2, 100%).
*
Differently substituted alkyl- and arylsulfonimides (21a−n) were
prepared as bioisosteres of 2 and 13a, respectively, to alter acidity or
modify lipophilicity without making significant changes to the core
structure or affecting pKa (Scheme 3; see also the Experimental
Section). Compounds were screened at 4 μM. A concentration of 5
μM of AA-substrate was employed. Mean
(E)-2-(5-Fluoro-1-((4-methyl-2-phenylpyrimidin-5-yl)methylene)-
1H-inden-3-yl)acetic Acid (13j). According to general procedure C,
the title compound was obtained from the isomer mixture 10a (0.05 g,
0.23 mmol) and 4-methyl-2-phenylpyrimidine-5-carbaldehyde (0.050
g, 0.25 mmol) after heating to 70 °C for 3 h and subsequent stirring at
ambient temperature overnight. The crude product was purified by
preparative thin-layer chromatography (SiO2, EtOAc/hexane, 0.5%
AcOH) to afford 43 mg (51%) of 13h: C23H17FN2O2, Mr = 372.40. 1H
NMR (400 MHz, DMSO-d6) δ: 2.69 (s, 3H), 3.67 (s, 2H), 6.87 (s,
1H), 7.11 (td, J = 2.4/8.4 Hz, 1H), 7.18 (dd, J = 2.4/9.2 Hz, 1H),
7.54−7.56 (m, 3H), 7.75 (s, 1H), 7.98 (dd, J = 5.2/8.4 Hz, 1H), 8.44−
8.47 (m, 2H), 8.82 (s, 1H). HPLC (method 1) tR: 10.16 min (97%,
UV347). LCMS (ESI) (method 2) tR: 2.95 min (97%, ELSD); m/z:
373.2 [M + 1]+.
a
SEM of two (n)
experiments.
or pathophysiological processes. However, some of the
inhibitors may have off-target effects that would limit their
utility in vivo. For example, compound 13a is a potent activator
of peroxisome proliferator-activated receptor (PPAR)γ in cell
culture.51 Interestingly, the SAR for activation of PPARγ
indicates that a free carboxyl group is absolutely required for
activity. Thus, analogues such as the trifluoromethylsulfoni-
mide, 21c, may be more useful as probes for COX-1 inhibition
in vivo.
(E)-2-(5-Fluoro-1-(4-(6-fluoropyridin-3-yl)benzylidene)-1H-inden-
3-yl)acetic Acid (13k). According to general procedure E, the title
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Figure 5. OVCAR-3 cell growth inhibition by 1a (purple triangle, n.i.
at 250 μM), 1b (blue diamond; EC50, 210 μM), 2 (green circle; EC50,
223 μM), and 13a (red square; EC50, 132 μM).
1F, Pyr-F). HPLC (method 1) tR: 9.75 min. LCMS (ESI) (method 2)
tR: 2.70 min (≥95%, ELSD); m/z: 376.0 [M + 1]+.
Sodium (E)-2-(1-([1,1′-Biphenyl]-4-ylmethylene)-5-methoxy-1H-
inden-3-yl)acetate [15b(Na)]. The title compound was prepared by
the aldol condensation reaction specified in general procedure D (step
1) from the isomer mixture 10b (0.050 g, 0.22 mmol) and
commercially available [1,1′-biphenyl]-4-carbaldehyde (0.043 g, 0.24
mmol). After stirring for 72 h at room temperature, the accumulated
product precipitate was filtered and washed first with a little ice-cold
methanol and then with diethylether. Compound 15b was obtained as
a yellow solid (Na-salt) in 37% yield (31.5 mg): C25H19NaO3, Mr =
390.41. 1H NMR (300 MHz, DMSO-d6) δ: 3.23 (s, 2H), 3.79 (s, 3H),
6.74 (dd, J = 2.22/8.22 Hz, 1H), 6.89 (s, 1H), 6.99 (d, J = 2.22 Hz,
1H), 7.34−7.41 (m, 2H), 7.47−7.52 (m, 2H), 7.65 (d, J=8.22 Hz,
1H), 7.73−7.79 (m, 6H).
(E)-2-(1-([1,1′-Biphenyl]-4-ylmethylene)-5-methoxy-1H-inden-3-
yl)acetic Acid (15b). The title compound was prepared according to
general procedure D (step 2) using 200 μL of 1.5 N HCl, starting from
15b(Na) (0.016 g, 0.041 mmol) in 1 mL of H2O. Yield, 13 mg (86%):
1
C25H20O3, Mr = 368.42. H NMR (400 MHz, DMSO-d6) δ: 3.64 (s,
Figure 4. (a) Inhibition of COX-1 in ovarian cancer cells. The
OVCAR-3 human ovarian epithelial cancer cell line expresses high
levels of catalytically active COX-1 but no COX-2 (see Western blot
above).36 Whole-cell lysates from the OVCAR-3 human ovarian
epithelial cancer cell lines were fractionated on a 10% PAGE and
probed with polyclonal antibodies specific for COX-1 and COX-2.
The control lane for the COX-1 blot is a standard solution of 0.3 μg/
μL purified oCOX-1 in M-PER and Laemmli sample buffer, whereas
the control lane for the COX-2 blot is a standard solution of 0.3 μg/μL
purified mCOX-2 in M-PER and Laemmli sample buffer. Lower graph:
Inhibition of hCOX-1 in OVCAR-3 cells (8 μM 14C-AA, 30 min at 37
°C) by E-DMSS analogues 2 (green circle; IC50, 116 nM), 13a (red
triangle; IC50, 300 nM), and 21c (blue square; IC50, 495 nM) in
comparison with literature reference compounds 5 (brown diamond;
2H), 3.80 (s, 3H), 6.81 (dd, J = 2.4/8.2 Hz, 1H), 6.92 (d, J = 2.0 Hz,
1H), 7.05 (s, 1H), 7.39 (tt, J = 0.8/2.0/7.2 Hz, 1H), 7.47−7.51 (m,
3H), 7.72−7.79 (m, 7H). LCMS (ESI) (method 2) tR: 3.14 min
(≥95%, ELSD); m/z: 369.2 [M + 1]+.
(E)-Isopropyl 2-(5-fluoro-1-(4-(methylthio)benzylidene)-1H-
inden-3-yl)acetate (16c). According to general procedure F, (E)-2-
(5-fluoro-1-(4-(methylthio)benzylidene)-1H-inden-3-yl)acetic acid 2
(100 mg, 0.31 mmol) was subjected to reaction with 2-propanol (5
mL) to afford 16c as a fluffy yellow solid. Yield, 118 mg (100%).
1
C22H21FO2S, Mr = 368.46. H NMR (400 MHz, DMSO-d6) δ: 400
MHz: 1.19 (d, J = 6.4 Hz, 6H), 2.52 (s, 3H), 3.72 (s, 2H), 4.94 (sept, J
= 6.4 Hz, 1H), 7.05 (td, J = 8.9/2.4 (1.2) Hz, 1H), 7.13−7.15 (m,
2H), 7.35 (d, J = 8.4 Hz, 2H), 7.59−7.64 (m, 3H), 7.83 (dd, J = 8.4/
5.2 Hz, 1H). 19F NMR (282 MHz, DMSO-d6) δ: −113.39 (1F, C5′-F).
LCMS (ESI) 3.60 min (>99%, ELSD); m/z: 369.2 [M + 1]+.
(E)-2-(5-Fluoro-1-(4-(methylthio)benzylidene)-1H-inden-3-yl)-2-
methylpropanoic Acid (19a). Ester cleavage as described in general
procedure G_variant2 was performed on 19b (15 mg, 0.039 mmol).
The crude product was purified by flash chromatography (ethyl
acetate/hexane 1:1, 0.5% HOAc, gradient) to produce 19a. Yield, 12.5
○
positive control; IC50, 160 nM) and 6 ( ; negative control 16%
inhibition at 5 μM). (b) Inhibition of hCOX-2 in HNSCC 1483 cells
by E-DMSS analogues 2 (blue circle, n.i. at 5 μM) and 13a (red
square, n.i. at 5 μM) in comparison with literature reference
○
compound 6 ( ; positive control; IC50, 54 nM).
compound was obtained from (E)-2-(1-(4-bromobenzylidene)-5-
fluoro-1H-inden-3-yl)acetic acid 11i (0.50 g, 0.14 mmol) and 2-
fluoro-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridine (0.037
g, 0.17 mmol) after 14 h at 90 °C. The crude product was purified
by recrystallization from MeOH/hexanes. Yield, 25 mg (48%), bright
yellow solid: C23H15F2NO2, Mr = 375.37. 1H NMR (400 MHz,
DMSO-d6) δ: 3.69 (s, 2H), 7.07 (td, J = (1.2)2.4/8.8 Hz, 1H), 7.15−
7.18 (m, 2H), 7.31 (dd, J = 2.8/8.8 Hz, 1H), 7.69 (s, 1H), 7.79−7.88
(m, 5H), 8.36 (td, J = 2.8/8.2 Hz, 1H), 8.63 (d, J = 2.8 Hz, 1H). 19F
NMR (282 MHz, DMSO-d6) δ: −112.96 (d, 1F, C5′-F), −68.78 (d,
1
mg (90%). C21H19FO2S, Mr = 354.44. H NMR (400 MHz, DMSO-
d6) δ: 1.53 (s, 6H), 2.53 (s, 3H), 6.98 (dd, J = 2.4/10.0 Hz, 1H),
7.02−7.07 (m, 2H), 7.36 (d, J = 8.8 Hz, 2H), 7.60 (s, 1H), 7.66 (d, J =
8.4 Hz, 2H), 7.86 (dd, J = 5.4/8.2 Hz, 1H). 19F NMR (282 MHz,
DMSO-d6) δ: −113.31 (q, 1F, C5′-F). LCMS (ESI) (method 2) tR:
3.12 min (98%, ELSD); m/z: 355.2 [M + 1]+.
(E)-Ethyl 2-(1-([1,1′-biphenyl]-4-ylmethylene)-5-fluoro-1H-inden-
3-yl)-2-methylpropanoate (19d). The title compound was prepared
by the aldol condensation reaction specified in general procedure D
(step 1) from 10d (0.10 g, 0.40 mmol) and commercially available
[1,1′-biphenyl]-4-carbaldehyde (0.081 g, 0.44 mmol). After stirring for
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Figure 6. SAR for selective COX-1 inhibition.
Figure 7. Derivatization and COX activity data of lead compound 13a.
72 h at room temperature, the accumulated product precipitate was
filtered and carefully washed with water. Compound 19d was obtained
as a yellow solid (ethyl ester) in 98% yield (163 mg): C28H25FO2, Mr =
7.2 Hz, 2H), 6.91 (dd, J = 2.0/9.6 Hz, 1H), 7.07 (td, J = 2.4/8.8 Hz,
1H), 7.38 (pseudo t, J = 8.8 Hz, 2H), 7.61−7.63 (m, 2H), 7.87−8.00
(m, 3H), 8.07 (s, 1H), 8.20−8.24 (dd, J = 5.6/8.8 Hz, 2H). 19F NMR
(282 MHz, DMSO-d6) δ: −111.98 (s, 1F), −110.74 (s, 1F). LCMS
(ESI) (method 2) tR: 3.79 min (>99%, ELSD); m/z: 432.2 [M + 1]+.
(E)-2-(1-([1,1′-Biphenyl]-4-ylmethylene)-5-fluoro-1H-inden-3-yl)-
N-((trifluoromethyl)sulfonyl)-acetamide (21c). According to general
procedure J, (E)-2-(1-([1,1′-biphenyl]-4-ylmethylene)-5-fluoro-1H-
inden-3-yl)acetyl chloride (20 mg, 0.053 mmol) was subjected to
reaction with trifluoromethanesulfonamide (11.9 mg, 0.080 mmol).
The crude product was purified by flash chromatography (SiO2,
EtOAc + hexane: 1 + 1 (0.5% AcOH, gradient) to afford 13.5 mg
1
412.50. H NMR (400 MHz, DMSO-d6) δ: 1.07 (t, J = 7.2 Hz, 3H),
1.57 (s, 6H), 4.09 (q, J = 7.2 Hz, 2H), 6.90 (dd, J = 2.4/9.6 Hz, 1H),
7.05−7.10 (m, 2H), 7.40 (tt, J = 7.2 Hz, 1H), 7.50 (t, J = 7.2 Hz, 1H),
7.72−7.76 (m, 3H), 7.81 (s, 4H), 7.91 (dd, J = 5.2/8.4 Hz, 1H).
LCMS (ESI) (method 2) tR: 3.89 min (>99%, ELSD); m/z: 413.2 [M
+ 1]+.
(E)-Ethyl 2-(5-fluoro-1-((6-(4-fluorophenyl)pyridin-2-yl)-
methylene)-1H-inden-3-yl)-2-methyl-propanoate (20b). The title
compound was prepared by the aldol condensation reaction specified
in general procedure D (step 1) from 10d (0.050 g, 0.20 mmol) and
commercially available 6-(4-fluorophenyl)picolin-aldehyde (0.045 g,
0.22 mmol). After stirring for 72 h at room temperature, the
accumulated product precipitate was filtered and carefully washed with
water. The title compound was obtained as a yellow solid (Na salt) in
1
(52%) of 21c as bright yellow solid. C25H17F4NO3S, Mr = 487.47. H
NMR (400 MHz, DMSO-d6) δ: 3.47 (s, 2H), 7.02 (td, J = 2.4/8.8 Hz,
1H), 7.09 (s, 1H), 7.15 (dd, J = 2.4/9.4 Hz, 1H), 7.39 (tt, J = 1.6/7.2
Hz, 1H), 7.49 (t, J = 7.2 Hz, 2H), 7.59 (s, 1H), 7.74 (dd, J = 1.6/7.2
Hz, 2H), 7.78 (s, 4H), 7.82 (dd, J = 5.2/8.4 Hz, 1H). 19F NMR (282
MHz, DMSO-d6) δ: −115.25 (s, 1F, C5′-F), −77.31 (s, 3F, −CF3).
1
83% yield (72.5 mg): C27H23F2NO2, Mr = 431.47. H NMR (400
MHz, DMSO-d6) δ: 1.06 (t, J = 7.2 Hz, 3H), 1.59 (s, 6H), 4.08 (q, J =
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LCMS (ESI) (method 2) tR: 3.62 min (>99%, UV254, ELSD); m/z:
(10) Al-Hourani, B. J.; Sharma, S. K.; Mane, J. Y.; Tuszynski, J.;
Baracos, V.; Kniess, T.; Suresh, M.; Pietzsch, J.; Wuest, F. Synthesis
and evaluation of 1,5-diaryl-substituted tetrazoles as novel selective
cyclooxygenase-2 (COX-2) inhibitors. Bioorg. Med. Chem. Lett. 2011,
21, 1823−1826.
488.0 [M + 1]+.
ASSOCIATED CONTENT
* Supporting Information
■
S
(11) Pairet, M.; Churchill, L.; Trummlitz, G.; Engelhardt, G.
Differential inhibition of cyclooxygenase-1 (COX-1) and −2 (COX-
2) by NSAIDS: Consequences on anti-inflammatory activity versus
gastric and renal safety. Inflammopharmacology 1996, 4, 61−70.
(12) Prasit, P.; Riendeau, D. Selective cyclooxygenase-2 inhibitors.
Annu. Rep. Med. Chem. 1997, 32, 211−220.
Synthetic procedures, routine spectroscopic and spectrometric
data, HPLC data, exemplified NMR spectra, and biochemical
and biological testing methods. This material is available free of
charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
*Tel: 615-343-7329. Fax: 615-343-7534. E-mail: larry.
marnett@vanderbilt.edu.
(13) Talley, J. J. Selective inhibitors of cyclooxygenase-2 (COX-2).
Prog. Med. Chem. 1999, 36, 201−234.
■
(14) Talley, J. J.; Bertenshaw, S. R.; Brown, D. L.; Carter, J. S.;
Graneto, M. J.; Koboldt, C. M.; Masferrer, J. L.; Norman, B. H.;
Rogier, D. J. Jr.; Zweifel, B. S.; Seibert, K. 4,5-Diaryloxazole inhibitors
of cyclooxygenase-2 (COX-2). Med. Res. Rev. 1999, 19, 199−208.
(15) Chan, C. C.; Boyce, S.; Brideau, C.; Charleson, S.; Cromlish,
W.; Ethier, D.; Evans, J.; Ford-Hutchinson, A. W.; Forrest, M. J.;
Gauthier, J. Y.; Gordon, R.; Gresser, M.; Guay, J.; Kargman, S.;
Kennedy, B.; Leblanc, Y.; Leger, S.; Mancini, J.; O'Neill, G. P.; Ouellet,
M.; Patrick, D.; Percival, M. D.; Perrier, H.; Prasit, P.; Rodger, I.;
Tagari, P.; Therien, M.; Vickers, P.; Visco, D.; Wang, Z.; Webb, J.;
Wong, E.; Xu, L. J.; Young, R. N.; Zamboni, R.; Riendeau, D.
Rofecoxib [Vioxx, MK-0966; 4-(4′-methylsulfonylphenyl)-3-phenyl-2-
(5H)-furanone]: A potent and orally active cyclooxygenase-2 inhibitor.
Pharmacological and biochemical profiles. J. Pharmacol. Exp. Ther.
1999, 290, 551−560.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work was supported by the NIH (National Cancer
Institute, CA89450, and the National Foundation for Cancer
Research). A.J.L. gratefully acknowledges funding from the
German Research Foundation (DFG-Forschungsstipendium,
GZ: LI2019/1-1, Einzelprojekt). We are grateful to Dr. Donald
Stec for assistance with NMR analysis and to Dr. Carol Rouzer
for proofreading.
(16) Esser, R.; Berry, C.; Du, Z.; Dawson, J.; Fox, A.; Fujimoto, R. A.;
Haston, W.; Kimble, E. F.; Koehler, J.; Peppard, J.; Quadros, E.;
Quintavalla, J.; Toscano, K.; Urban, L.; van Duzer, J.; Zhang, X.; Zhou,
S.; Marshall, P. J. Preclinical pharmacology of lumiracoxib: A novel
selective inhibitor of cyclooxygenase-2. Br. J. Pharmacol. 2005, 144,
538−550.
(17) Marnett, L. J. The COXIB experience: A look in the rearview
mirror. Annu. Rev. Pharmacol. Toxicol. 2009, 49, 265−290.
(18) Rodriguez, L. A. G.; Tolosa, L. B. Risk of upper gastrointestinal
complications among users of traditional NSAIDs and COXIBs in the
general population. Gastroenterology 2007, 132, 498−506.
ABBREVIATIONS USED
■
NSAID, nonsteroidal anti-inflammatory drug; PPAR, perox-
isome proliferator-activated receptor; COX, cyclooxygenase;
SAR, structure−activity relationship; PG, prostaglandin; AA,
arachidonic acid; RPMI, Roswell Park Memorial Institute
medium; HBSS, Hank's balanced salt solution; FBS, fetal
bovine serum; mPGES-1, microsomal prostaglandin E2
synthase-1; PBS, phosphate-buffered saline; M-PER, mamma-
lian protein extraction reagent
(19) Hippisley-Cox, J.; Coupland, C.; Logan, R. Risk of adverse
gastrointestinal outcomes in patients taking cyclo-oxygenase-2
inhibitors or conventional non-steroidal anti-inflammatory drugs:
Population based nested case-control analysis. BMJ [Br. Med. J.]
2005, 331, 1310−1312.
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