Synthesis and biological evaluation of novel thiazolidinedione analogues as 15-hydroxyprostaglandin dehydrogenase inhibitors

Article abstract of DOI:10.1021/jm200390u

Novel thiazolidinedione analogues as 15-hydroxyprostaglandin dehydrogenase (15-PGDH) inhibitors were synthesized. Compounds 2, 3, and 4 exhibited IC ₅₀ of 25, 8, and 19 nM, respectively. They also significantly increased levels of PGE₂ in A549 cells. To assess the influence of 15-PGDH inhibitor on cochlear blood flow (CBF), 2 was applied intravenously to guinea pigs. It increased their CBFs. Scratch wounds were also analyzed in confluent monolayers of HaCaT cells. Cells exposed to 4 showed significantly improved wound healing with respect to a control.

Full text of DOI:10.1021/jm200390u

BRIEF ARTICLE
pubs.acs.org/jmc
Synthesis and Biological Evaluation of Novel Thiazolidinedione
Analogues as 15-Hydroxyprostaglandin Dehydrogenase Inhibitors
Ying Wu,† Sandeep Karna,‡ Cheol Hee Choi,‡,§ Min Tong,|| Hsin-Hsiung Tai,|| Dong Hee Na,^
Chul Ho Jang,#,‡ and Hoon Cho*,†,‡
†Department of Polymer Science and Engineering, Chosun University, Gwangju 501-759, South Korea
‡Research Center for Resistant Cells, Chosun University, Gwangju 501-759, South Korea
§Department of Pharmacology, Chosun University Medical School, Gwangju 501-759, South Korea
Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky, United States
^College of Pharmacy, Kyungsung University, Busan, South Korea
#Department of Otolaryngology, Chonnam National Medical School, Gwangju, South Korea
ABSTRACT: Novel thiazolidinedione analogues as 15-hydroxyprostaglandin dehydrogenase (15-PGDH) inhibitors were
synthesized. Compounds 2, 3, and 4 exhibited IC50 of 25, 8, and 19 nM, respectively. They also significantly increased levels of
PGE2 in A549 cells. To assess the influence of 15-PGDH inhibitor on cochlear blood flow (CBF), 2 was applied intravenously to
guinea pigs. It increased their CBFs. Scratch wounds were also analyzed in confluent monolayers of HaCaT cells. Cells exposed to 4
showed significantly improved wound healing with respect to a control.
’ INTRODUCTION
dehydrogenase (15-PGDH).9 This enzyme is ubiquitous in mam-
malian tissue and is responsible for the biological inactivation of
prostaglandins because 15-ketoprostaglandins is significantly less
biologically active.10 Therefore, inhibitors of 15-PGDH will be
valuable for the therapeutic management of diseases requiring
elevated prostaglandin levels.
Previous work has shown that the antidiabetic drug ciglitazone
and its analogue 5-(4-(2-cyclohexylethoxy)benzylidene)thiazoli-
dine-2,4-dione 1 (CT-8) (Chart 1) are potent inhibitors of 15-
PGDH.11ꢀ13 Because of this, a series of thiazolidinedione analogues
with different substituents on phenyl rings were prepared in order to
investigate the relationship between structure and 15-PGDH inhibi-
tion. Furthermore, human lung adenocarcinoma A549 cells were
used as a model system to show that the inhibition of 15-PGDH may
lead to increased accumulation of PGE2, indicating that 15-PGDH
inhibitors may be valuable for the therapeutic management of
diseases in which elevated prostaglandin levels are needed.
Naturally occurring prostaglandins, mainly prostaglandin E1
(PGE1) and prostaglandin E2 (PGE2), are important mediators
in the gastric mucosa, renal medulla, and microvascular endothelium
and in controlling other physiological functions. PGE1, a potent
vasodilator and inhibitor of platelet aggregation, is well-known as a
useful drug for peripheral arterial disease such as Raynaud’s and
Burerger’s diseases and diabetic neuropathy.1 PGE2 is crucial to the
control of various physiological functions. Recent clinical studies
have demonstrated that the prostaglandin analogue latanoprost
causes the growth of body hair and eyelashes in humans and
animals.2 In humans, trials carried out on the scalp have shown that
PGE2 could increase hair density.3 PGE2 has been identified as an
important mediator of gastric ulcer healing,4 bone formation,5 and
dermal wound healing.6 Both these prostaglandins are also potent
stimulants of human uterine contractility at any stage of pregnancy
and also cause cervical ripening and dilatation. These characteristics
have been found clinically useful for different purposes during
pregnancy. However, local administration of prostaglandin is an
unacceptable therapeutic option for human diseases because of the
limited knowledge of the potential changes caused by it on the tissue
at cellular level and the biological instability of prostaglandins.
Therefore, a number of prostaglandin analogues that are resistant
to rapid inactivation have been developed for clinical use. Misopros-
tol, (11R,13E)-11,16-dihydroxy-16-methyl-9-oxoprost-13-en-1-oic
acid methyl ester, is a PGE1 analogue used for the treatment and
prevention of peptic ulcers caused by nonsteroidal anti-inflammatory
drugs.7 Misoprostol has more recently been used to induce labor and
to treat postpartum hemorrhage.8 The only parent prostaglandin still
in extended clinical use is PGE2, mainly for cervical ripening at term
and for induction of labor.
’ CHEMISTRY
The thiazolidine-2,4-dione derivatives listed in Table 1 were
prepared by the method shown in Scheme 1. The connection of
cyclohexylalcohol to the central arylaldehyde was accomplished via
Mitsunobu coupling to produce an intermediate aldehyde with a
yield of 60ꢀ80%. Knoevenagel condensation between intermediate
aldehyde and 2,4-thiazolidinedione in refluxing toluene, containing a
catalytic amount of piperidinium acetate, gave the benzylidenethia-
zolidine-2,4-dione, which crystallized from the reaction mixture in
high purity. p-Hydroxybenzaldehyde, as a starting material, was
reacted with various substrates to produce an intermediate substi-
tuted benzaldehyde in good yield. The intermediate was then used
in the coupling reaction with thiazolidine-2,4-dione to afford the
Prostaglandins have a short lifetime in vivo because they are
metabolized rapidly by oxidation to 15-ketoprostaglandins catalyzed
by the cytosolic enzyme NAD+-dependent 15-hydroxyprostaglandin
Received: April 5, 2011
Published: June 08, 2011
r
2011 American Chemical Society
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|

Journal of Medicinal Chemistry
BRIEF ARTICLE
Chart 1. Structures of Ciglitazone and Compound 1 (CT-8)
with IL-1β (1 ng/mL) overnight (18 h) to generate PGE2. The
compounds were then added, and incubation continued for 5 h. The
medium was collected, and the level of PGE2 was analyzed by
enzyme immunoassay.
Effect on Cochlear Blood Flow (CBF). Compound 2 was
administered intravenously to guinea pigs. Healthy males each
weighing 250 g were used for CBF analysis. The animals were
housed at a constant 22 ꢀC with 50% humidity. Ambient noise levels
were below 40 dB. Compound 2 was applied at the indicated
concentrations, and CBF was measured by a computer equipped
with a data acquisition program (PowerLab, AD Instruments).
Scratch Wound Test. Scratch wound analysis was performed
in confluent monolayers of HaCaT cells. HaCaT cells were plated
in a six-well plate at ∼5 ꢁ 105 cells per well and maintained in
DMEM medium supplemented with 10% fetal bovine serum and
10 μg/mL mitomycin in a humidified atmosphere containing 5%
CO2 at 37 ꢀC. The cells were incubated until ∼80% confluence was
reached. The cells cultured in the six-well plate were mechanically
scratchedwithasterile200μL pipet tip and incubated under control
conditions in the presence of 5 μM 4. The width of the wound was
measured upon wounding and after treatment using an inverted
microscope equipped with a digital camera.
Table 1. Inhibitory Potency of Various Synthetic Thiazoli-
dine-2,4-dionesa
compd
R1
R2
IC50 (μM)
1
H
H
0.051
0.025
>50
2
OCH3
OCH3
Cl
H
2a
3
CH3
H
0.008
Quantitative Real-Time PCR. A549 cells were plated in a
six-well plate at ∼5 ꢁ 105 cells per well and maintained in
RPMI medium supplemented with 10% fetal bovine serum and
100 μg/mL penicillin in a humidified atmosphere containing 5%
CO2 at 37 ꢀC overnight. 15-PGDH inhibitors were added at
5 μM, and incubation continued for 25 h. Levels of gene
expression were then assayed by real-time PCR.
4
Br
H
0.019
a The enzyme was assayed fluorometrically as described in the text. IC50
values were determined using NAD+ (250 μM) as coenzyme and PGE2
(21 μM) as substrate. 15-PGDH was expressed as a GST fusion enzyme
using pGEX-2T vector as described in the text.
Scheme 1. Synthesis of Compounds 2ꢀ8a
’ RESULTS AND DISCUSSION
Thiazolidinediones are well-known synthetic chemical entities
that have been found to have several important biological activities.
Ciglitazone was the first thiazolidinedione found to exhibit anti-
hyperglycemic activity.14 Previous studies have shown that the
antidiabetic drug ciglitazone and its derivatives are potent inhibitors
of 15-PGDH by a noncompetitive and an uncompetitive inhibition
mechanism with NAD+ and PGE2 substrates, respectively.11 The
structures of these thiazolidinediones are shown in Chart 1. On the
basis of this, a series of thiazolidinediones analogues with different
substituents on the phenyl ring were prepared in order to investigate
the structureꢀactivity relations of 15-PGDH inhibition.
a Reagents and conditions: (a) PPh3, DEAD, THF, 25 ꢀC, 18 h; (b)
piperidine, AcOH, reflux, 12 h.
appropriate thiazolidinedione derivatives. Finally, control compound
2a was synthesized from 2 with methyl iodide in the presence of a
catalytic amount of NaH. All the compounds were characterized by
1H NMR. Molecular weights of all compounds were identified using
an Agilent Technologies series 1100 LC/MSD VL system (Palo
Alto, CA, U.S.) with flow injection analysis using 50% acetonitrile in
water containing 0.1% formic acid. The mass spectrometer was
operated in negative ion mode. The purity of all compounds was
determined using reversed-phase HPLC with a Hypersil Gold C-18
column (250 mm ꢁ 4.6 mm i.d., 5 μm, Thermo Scientific,
Bellefonte, PA, U.S.). Samples were eluted by isocratic elution using
55% acetonitrile in water containing 0.1% trifluoroacetic acid at a
flow rate of 1.0 mL/min. UV absorbance was monitored at 320 nm.
Purity of all compounds was g95%.
The substituents were introduced at the phenyl moiety of 1
described in Scheme 1. The introduction of a chlorine atom at the
C3 of 1 showed a great increase in inhibitory potency with IC50 of 8
nM, as shown in Table 1. The introduction of a bromine atom at the
C3 of 1 also showed a great increase in inhibitory potency with an
IC50 of 19 nM. For structureꢀactivity analysis, cyclohexyl was
introduced with different chain lengths to the hydroxyl group of
5-(3-chloro-4-hydroxybenzylidene)thiazolidine-2,4-dione, and the
effects of these derivatives were tested. Deletion of the methylene
group between cyclohexyl ring and the oxygen of 5-(3-chloro-
4-(2-cyclohexylethoxy)benzylidene)thiazolidine-2,4-dione (3) de-
creased inhibitory potency, as shown in Table 2. Further addition of
a methylene group significantly decreased the inhibitory potency, as
indicated by 8. It also appears that two methylene groups between
the cyclohexyl ring and oxygen of 5-(3-chloro-4-hydroxybenzylidene)-
thiazolidine-2,4-dione are optimal for inhibitory activity. The
most potent inhibitor of this series of compounds is 3, (5-(3-
chloro-4-(2-cyclohexylethoxy)benzyl)thiazolidine-2,4-dione), with
’ BIOLOGICAL EVALUATION
Inhibition of 15-PGDH. The new compounds were tested for
the inhibition of human 15-PGDH expressed in Escherichia coli.
Inhibitory effects were observed using a fluorescence spectrophot-
ometer that monitored the formation of NADH by measuring
emission at 468 nm following excitation at 340 nm. Compounds
were also tested in cellular situations: A549 cells were stimulated
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BRIEF ARTICLE
Table 2. Inhibitory Potency of Various Synthetic Thiazoli-
dine-2,4-dionesa
compd
n
IC50 (μM)
5
6
3
7
8
0
1
2
3
4
0.047
0.028
0.008
0.010
0.024
Figure 2. Inhibition of 15-PGDH in A549 cells. A549 cells were seeded
in six-well culture plates in RPMI medium containing fetal bovine serum
and antibiotic. They were incubated overnight at 5% CO2 and 37 ꢀC. A549
cells were treated by 15-PGDH inhibitors at 5 μM, and PGE2 levels were
assayed by PGE2 enzyme immunoassay as described in the text. Data were
analyzed from results of three independent experiments.
a The enzyme was assayed fluorometrically as described in the text. IC50
values were determined using NAD+ (250 μM) as coenzyme and PGE2
(21 μM) as substrate. 15-PGDH was expressed as a GST fusion enzyme
using pGEX-2T vector as described in the text.
Figure 1. Inhibition of 15-PGDH in IL-1β-stimulated A549 cells. A
single clone of 15-PGDH stably transfected A549 cell line was maintained in
RPMI-1640 medium supplemented with 10% fetal calf serum (FBS) and
1 mg/100 mL gentamicin in a humidified atmosphere containing 5% CO2
at 37 ꢀC. Cells were plated in 24-well plate (0.5 mL per well) at about 105
cells per well in duplicate and grown for 24 h before stimulation with IL-1β
(1 ng/mL) overnight (18 h) to generate PGE2. Compounds 2 and 2a were
added at the indicated concentrations, and the incubation continued for 5 h.
Medium was collected, and the level of PGE2 was analyzed by enzyme
immunoassay as described in the text. Data were analyzed from results of
five independent experiments.
Figure 3. Cochlear blood flow (CBF) after intravenous administration
of 15-PGDH inhibitor. Healthy male guinea pigs each weighing 250 g were
used to measure CBF. The animals were housed at a constant 22 ꢀC and
50% humidity. Ambient noise was below 40 dB. Compound 2 and
papaverine as positive control were applied at the indicated concentrations,
and CBF was measured by a computer equipped with a data acquisition
program (PowerLab, AD Instruments) as described in the text. Data were
analyzed from results of three independent experiments.
values were expressed relative to the baseline value, which was set
at 100% for each condition. CBF began to increase after 30 min,
reaching plateaus of 22% 40 min after the intravenous application
of 10 μg and 65% 50 min after the application of 20 μg. The
plateau levels were maintained for at least 10 min (Figure 3).
Re-epithelialization is an important part of wound healing.
The healing of wounds is complex and involves the formation of a
clot, an inflammatory response, accumulation of granulation tissue,
and the deposition and remodeling of an extracellular matrix.15 It also
requires the interaction of cells in the epidermis and the dermis and
mediators released from inflammatory cells, fibroblasts, and kera-
tinocytes.16 Many factors influence wound healing, including growth
factors, cytokines, metalloproteinases, and extracellular matrix
(ECM) proteins,16 and the exogenous application of some of these
factors has been shown to aid healing.17 Many studies have reported
that PGE2 is an important mediator of dermal wound healing with
specific effects on fibroblast behavior. Kolodsick et al.18 reported that
PGE2 can inhibit the differentiation of fibroblast into myofibroblasts
an IC50 of 8 nM. A summary of the inhibitory potencies of all
these compounds is listed in Tables 1 and 2.
To evaluate the selectivity of 2 for inhibition of 15-PGDH in
IL-1β-stimulated A549 cells, 2 and 2a were added at various
concentrations and incubated for 5 h. Medium was then col-
lected, and the level of PGE2 was analyzed by enzyme immu-
noassay. The results show that the level of PGE2 was dose-
dependently increased as shown in Figure 1. In addition, A549
cells were treated by 1, 2, 3, and 4, each at 5 μM, and PGE2 levels
were assayed by PGE2 enzyme immunoassay. The results also
show that levels of PGE2 were significantly increased, as shown in
Figure 2. These results suggest that thiazolidinedione derivatives
as 15-PGDH inhibitors may have utility for the therapeutic
management of diseases requiring elevated prostaglandin levels.
To assess the effect of 15-PGDH inhibitor on CBF, 2 was
applied intravenously to healthy male guinea pigs. The CBF
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Journal of Medicinal Chemistry
BRIEF ARTICLE
Figure 4. Scratch wound healing of HaCaT confluent monolayers. HaCaT cells were plated in a 6-well plate at ∼5 ꢁ 105 cells per well and maintained in
DMEM medium supplemented with 10% fetal bovine serum and 10 μg/mL mitomycin in a humidified atmosphere containing 5% CO2 at 37 ꢀC. The
cells were incubated until ∼80% confluence was reached. The cells were mechanically scratched with a sterile 200 μL pipet tip and incubated under
control conditions in the presence of 1 ng of TGF-β1 as positive control and in the presence of 5 μM 4 and observed 48 h after wounding.
via the EP2 receptor pathway through the up-regulation of cAMP.
To study wound healing, a scratch was made using a sterile 200 μL
pipet tip in a HaCaT cell line. Confluent monolayers of HaCaT were
scratch wounded as described in the methods section and then
allowed to re-epithelialize for 48 h at 37 ꢀC in the presence or absence
of 4 at 5 μM. Cells exposed to 4 showed significantly improved
wound healing after 48 h with respect to a control (Figure 4).
To evaluate the effect of 15-PGDH inhibitors on the regulation
of COX-1/2, MRP4, and PGT in cells, real time PCR was studied
against COX-1/2, MRP4, and PGT in A549 cell lines. The real time
PCR data showed that 2 and 3 inhibited COX-1 expression; they
induced hPGT expression and had no significant effect on COX-2
or MRP4 expression. These data suggest a decrease of PGE2 level in
extracellular. However, the results show that the levels of PGE2 in
extracellular were significantly increased, as shown in Figure 2.
These results suggest that the compounds have major biological
roles as 15-PGDH inhibitors, resulting in increased extracellular
levels of PGE2.
wound testing showed that 4 could induce a significant increase
of wound repair in HaCaT. Therefore, 15-PGDH inhibitors may
be useful to treat diseases such as Raynaud’s and Burerger’s
diseases, diabetic neuropathy, and wounds, which require ele-
vated prostaglandin levels.
’ EXPERIMENTAL SECTION
General Procedures for the Synthesis of 2ꢀ8. To a stirring
solution of 2-cyclohexylethanol (1.0 g, 7.80 mmol), 4-hydroxy-3-meth-
oxybenzaldehyde (1.2 g, 7.80 mmol), and triphenylphosphine (2.25 g,
8.58 mmol) in THF (20 mL) was slowly added diethyl azodicarboxylate
(40% in toluene, 3.74 g, 8.58 mmol) over 10 min at 0 ꢀC. The mixture
was then stirred at room temperature until the disappearance of starting
materials (TLC analysis). The resulting solution was concentrated
under reduced pressure and purified by column chromatography over
silica gel (elution with hexane/ethyl acetate, 20:1) to produce 1.72 g of
intermediate 4-(2-cyclohexylethoxy)-3-nitrobenzaldehyde (83.3%) as a
yellow oil. A mixture of 4-(2-cyclohexylethoxy)-3-methoxybenzalde-
hyde (1.0 g, 3.8 mmol), 2,4-thiazolidinedione (445 mg, 3.6 mmol),
piperidine (0.19 mL, 1.9 mmol), and acetic acid (0.11 mL, 1.9 mmol) in
toluene (20 mL) was then added to a round-bottom flask fitted with a
DeanꢀStark water trap and stirred under reflux for overnight. After the
mixture was cooled to room temperature, the precipitate was washed
with hexane and dried to produce 2.
’ CONCLUSIONS
PGE1, a strong vasodilator and platelet aggregation inhibitor,
is clinically used to treat diseases such as peripheral arterial
occlusive diseases and ductus arteriosus-dependent congenital
heart disease. PGE2 is also a physiologically important vasodi-
lator in several vascular beds and is in extended clinical use for
cervical ripening at term and to induce labor. However, they both
have very short half-lives in blood, oxidizing to 15-ketoprosta-
glandins catalyzed by 15-PGDH. On the basis of the structures of
previously synthesized thiazolidinedione analogues and their 15-
PGDH inhibitory activities, a series of thiazolidinedione analo-
gues with different substituents on the phenyl ring were prepared
using a series of reactions and tested for 15-PGDH inhibitory
activity. Novel derivatives of the 15-PGDH inhibitor 1 were
developed that showed improved potency. These included 2, 3,
and 4, which showed IC50 of 25, 8, and 19 nM, respectively.
These compounds also significantly increased levels of PGE2
following IL-1β stimulation compared to inactive analogue in
A549 cells. Compound 2 increased CBF in guinea pigs. Scratch
5-(4-(2-Cyclohexylethoxy)-3-methoxybenzylidene)thiazo-
lidine-2,4-dione (2). 2 was obtained by recrystallization from hex-
ane/ethyl acetate as a yellow solid (1.12 g, 83% yield). 1H NMR (300
MHz, DMSO-d6) δ 8.22 (s, 1H), 7.72 (s, 1H), 7.02 (d, J = 10.2 Hz, 2H),
6.92 (d, J = 10.2 Hz, 2H), 6.89 (s, 1H), 4.07 (t, J = 14.4 Hz, 2H), 3.84 (s,
3H), 1.71 (t, J = 14.4 Hz, 2H), 1.43ꢀ1.51 (m, 4H), 1.07ꢀ1.21 (m, 4H),
0.78ꢀ0.97 (m, 3H). MS (ESI): m/z 360 [M ꢀ H]ꢀ.
5-(3-Chloro-4-(2-cyclohexylethoxy)benzylidene)thiazoli-
dine-2,4-dione (3). 3 was obtained by recrystallization from hexane/
ethyl acetate as a yellow solid (1.21 g, 88% yield). 1H NMR (300 MHz,
DMSO-d6) δ 8.19 (s, 1H), 7.73 (s, 1H), 7.52 (s, 1H), 7.38 (d, J = 10.5
Hz, 1H), 7.01 (d, J = 10.5 Hz, 1H), 4.15 (t, J = 13.2 Hz, 2H), 1.80 (t, J =
13.2 Hz, 2H), 1.65ꢀ1.80 (m, 4H), 1.50ꢀ1.60 (m, 1H), 1.15ꢀ1.33
(m, 4H), 0.85ꢀ1.05 (m, 2H). MS (ESI): m/z 364 [M ꢀ H]ꢀ.
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Journal of Medicinal Chemistry
BRIEF ARTICLE
5-(3-Bromo-4-(2-cyclohexylethoxy)benzylidene)thiazoli-
dine-2,4-dione (4). 4 was obtained by recrystallization from hexane/
ethyl acetate as a yellow solid (1.08 g, 82% yield). 1H NMR (300 MHz,
DMSO-d6) δ 12.57 (s, 1H), 7.84 (s, 1H), 7.83 (s, 1H), 7.57 (d, J = 10.8
Hz, 1H), 7.28 (d, J = 10.8 Hz, 1H), 4.17 (t, J = 12.6 Hz, 2H), 1.61ꢀ1.75
(m, 7H), 1.46ꢀ1.52 (m, 1H), 1.06ꢀ1.26 (m, 3H), 0.89ꢀ0.96 (m, 2H).
MS (ESI): m/z 410 [M ꢀ H]ꢀ.
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5-(3-Chloro-4-(cyclohexyloxy)benzylidene)thiazolidine-2,
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1
acetate as a yellow solid (1.30 g, 88% yield). H NMR (300 MHz,
DMSO-d6) δ 12.58 (s, 1H), 7.72 (s, 1H), 7.69 (s, 1H), 7.51 (d, J = 13.2
Hz, 1H), 7.37 (d, J = 13.2 Hz, 1H), 4.56ꢀ4.61 (m, 1H), 2.02ꢀ2.49
(m, 2H), 1.69ꢀ1.86 (m, 2H), 1.50ꢀ1.53 (m, 2H), 1.35ꢀ1.45 (m, 4H).
MS (ESI): m/z 336 [M ꢀ H]ꢀ.
5-(3-Chloro-4-(cyclohexylmethoxy)benzylidene)thiazoli-
dine-2,4-dione (6). 6 was obtained by recrystallization from hexane/
ethyl acetate as a yellow solid (1.30 g, 88% yield). 1H NMR (300 MHz,
DMSO-d6) δ 12.58 (s, 1H), 7.72 (s, 1H), 7.69 (s, 1H), 7.52 (d, J = 8.7
Hz, 1H), 7.30 (d, J = 8.7 Hz, 1H), 3.94 (d, J = 6.0 Hz, 2H), 1.62ꢀ1.82
(m, 6H), 1.03ꢀ1.26 (m, 5H). MS (ESI): m/z 350 [M ꢀ H]ꢀ.
5-(3-Chloro-4-(cyclohexylpropoxy)benzylidene)thiazoli-
dine-2,4-dione (7). 7 was obtained by recrystallization from hexane/
ethyl acetate as a yellow solid (1.29 g, 88% yield). 1H NMR (300 MHz,
DMSO-d6) δ 12.58 (s, 1H), 7.71 (s, 1H), 7.69 (s, 1H), 7.53 (d, J = 8.4 Hz,
1H), 7.30 (d, J = 8.4 Hz, 1H), 4.12 (t, J= 12.6 Hz, 2H), 1.62ꢀ1.77 (m, 7H),
1.07ꢀ1.34 (m, 6H), 0.83ꢀ0.91 (m, 2H). MS (ESI): m/z 378 [M ꢀ H]ꢀ.
5-(3-Chloro-4-(cyclohexylbutoxy)benzylidene)thiazoli-
dine-2,4-dione (8). 8 was obtained by recrystallization from hexane/
ethyl acetate as a yellow solid (1.28 g, 87% yield). 1H NMR (300 MHz,
DMSO-d6) δ 12.58 (s, 1H), 7.73 (s, 1H), 7.69 (s, 1H), 7.53 (d, J = 9.0
Hz, 1H), 7.30 (d, J = 9.0 Hz, 1H), 4.14 (t, J = 12.3 Hz, 2H), 1.65ꢀ1.76
(m, 7H), 1.22ꢀ1.61 (m, 2H), 1.06ꢀ1.20 (m, 6H), 0.81ꢀ0.88 (m, 2H).
MS (ESI): m/z 392 [M ꢀ H]ꢀ.
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’ AUTHOR INFORMATION
Corresponding Author
*Phone: +82-62-230-7635. Fax: +82-62-232-2474. E-mail: hcho@
chosun.ac.kr.
’ ACKNOWLEDGMENT
(16) Martin, P. Wound healing—aiming for perfect skin regenera-
tion. Science 1997, 276, 75–81.
This work was supported by National Research Foundation of
Korea (NRF), funded by the Ministry of Education, Science and
Technology (MEST) through the Research Center for Resistant
Cells (R13-2003-009), Chosun University, Gwangju 501-759,
Republic of Korea.
(17) Werner, S.; Grose, R. Regulation of wound healing by growth
factors and cytokines. Physiol. Rev. 2003, 83, 835–870.
(18) Kolodsick, J. E.; Peters-Golden, M.; Larios, J.; Toews, G. B.;
Thannickal, V. J.; Moore, B. B. Prostaglandin E2 inhibits fibroblast to
myofibroblast transition via E. prostanoid receptor 2 signaling and cyclic
adenosine monophosphate elevation. Am. J. Respir. Cell Mol. Biol. 2003,
29, 537–544.
’ ABBREVIATIONS USED
PG, prostaglandin; 15-PGDH, 15-hydroxyprostaglandin dehy-
drogenase; PPARγ, peroxisome proliferator-activated receptor
γ; NAD+, nicotinamide adenine dinucleotide (oxidized form);
NADH, nicotinamide adenine dinucleotide (reduced form);
DTT, dithiothreitol; SDS, sodium dodecyl sulfate; EDTA, ethy-
lenediamine-N,N,N0,N0-tetraacetic acid; GST, glutathione S-
transferase; TLC, thin layer chromatography; THF, tetrahydro-
furan; DMSO, dimethylsulfoxide; DMF, N,N-dimethylforma-
mide; CBF, cochlear blood flow
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