Novel thiazolidinedione derivatives with anti-obesity effects: Dual action as PTP1B inhibitors and PPAR-γ activators

Article abstract of DOI:10.1016/j.bmcl.2010.08.130

Benzylidene-2,4-thiazolidinedione derivatives with substitutions at both the ortho and para-positions of the phenyl group were synthesized as PTP1B inhibitors with IC₅₀ values in a low micromolar range. Compound 18l, the lowest, bore an IC₅₀ of 1.3 μM. In a peroxisome proliferator-activated receptor-γ (PPAR-γ) promoter reporter gene assay, 18l was found to activate the transcription of the reporter gene with potencies comparable to those of troglitazone, rosiglitazone, and pioglitazone. In vivo efficacy of 18l as an anti-obesity and hypoglycemic agent was evaluated in a mouse model system. Compound 18l significantly suppressed weight gain and significantly improved blood parameters such as TG, total cholesterol and NEFA without overt toxic effects.

Full text of DOI:10.1016/j.bmcl.2010.08.130

Bioorganic & Medicinal Chemistry Letters 20 (2010) 6758–6763
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Novel thiazolidinedione derivatives with anti-obesity effects: Dual action
as PTP1B inhibitors and PPAR-c activators
Bharat Raj Bhattarai a, ,à, Bhooshan Kafle a, , Ji-Sun Hwang b, Seung Wook Ham c,
a,
Keun-Hyeung Lee a, Hwangseo Park d, Inn-Oc Han b, , Hyeongjin Cho
⇑
⇑
a Department of Chemistry, Inha University, Incheon 402-751, Republic of Korea
b Department of Physiology and Biophysics, College of Medicine, Inha University, Incheon 402-751, Republic of Korea
c Department of Chemistry, Chung Ang University, Seoul 156-756, Republic of Korea
d Department of Bioscience and Biotechnology, Sejong University, Seoul 143-747, Republic of Korea
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 13 July 2010
Revised 14 August 2010
Accepted 27 August 2010
Available online 17 September 2010
Benzylidene-2,4-thiazolidinedione derivatives with substitutions at both the ortho and para-positions of
the phenyl group were synthesized as PTP1B inhibitors with IC50 values in a low micromolar range. Com-
pound 18l, the lowest, bore an IC50 of 1.3 lM. In a peroxisome proliferator-activated receptor-c (PPAR-c)
promoter reporter gene assay, 18l was found to activate the transcription of the reporter gene with
potencies comparable to those of troglitazone, rosiglitazone, and pioglitazone. In vivo efficacy of 18l as
an anti-obesity and hypoglycemic agent was evaluated in a mouse model system. Compound 18l signif-
icantly suppressed weight gain and significantly improved blood parameters such as TG, total cholesterol
and NEFA without overt toxic effects.
Keywords:
Protein tyrosine phosphatase
Thiazolidinedione
PTP1B inhibitor
Ó 2010 Elsevier Ltd. All rights reserved.
PPAR-c activator
Anti-obesity
2,4-Thiazolidinediones (TZDs) have long been considered anti-
Recently, several studies have demonstrated TZD-like scaffolds
bind enzymes other than PPAR. Among those, azolidinediones
(e.g., A), a modified thiazolidinedione (e.g., B), and isothiazolidi-
nones (e.g., C) have been reported to inhibit protein tyrosine phos-
phatase 1B (PTP1B).9–11 PTP1B is a cytosolic protein tyrosine
phosphatase expressed in various cells, including liver, muscle
and fat.12 This enzyme is known to be an important negative reg-
ulator of insulin and leptin signaling cascades.13–15 Therefore,
PTP1B was proposed as a target for the treatment of diabetes, obes-
ity and other related metabolic diseases.16 Over the last decade,
numerous different PTP1B inhibitors have been reported.17–19
Among them, only two compounds, ertiprotafib and trodusque-
mine, have progressed to clinical trials. Ertiprotafib, however,
dropped in phase II due either to side effects or a low rate of
in vivo efficacy.20 Trodusquemine is currently in a phase I clinical
challenge with promising preclinical results in diet-induced obese
(DIO) rats.21 A first-in-class drug has yet to be launched, neverthe-
less, extensive research is under way to develop a potential block-
buster drug.
hyperglycemic compounds by ameliorating insulin resistance and
thereby normalizing elevated blood glucose levels.1–4 Some mem-
bers of this group, such as ciglitazone, troglatizone, rosiglitazone
and pioglitazone (Fig. 1), are known to have insulin-sensitizing ef-
fects and act as PPAR-c
agonists.5 Some of these compounds have
been marketed for the treatment of type 2 diabetes mellitus
(T2DM). Ciglitazone was not used as a medication but was devel-
oped as an anti-diabetic agent earlier than the marketed TZDs.6
Troglitazone, the first TZD marketed as an anti-diabetic agent,
was withdrawn due to liver toxicity in several patients.7 Rosiglitaz-
one and pioglitazone, the two drugs currently on the market in the
TZD class, are potent ligands of PPAR-c and show efficient insulin
sensitization in type 2 diabetes patients.8
Abbreviations: TZD, thiazolidinedione; T2DM, type 2 diabetes mellitus; PTP1B,
protein tyrosine phosphatase 1B; DIO, diet-induced obese; MOM, methoxy-
methyl; pNPP, p-nitrophenyl phosphate; HFD, high fat diet; LFD, low fat diet; TG,
triglycerides; NEFA, non-esterified fatty acids; FFA, free fatty acids; TLC, thin-layer
chromatography.
Previously reported compounds containing TZD or related scaf-
folds can be characterized by a central phenyl ring substituted by a
TZD-like group and a major substituent in a para-orientation, or
less commonly, meta- or ortho-orientations. In a recent study, we
synthesized TZD derivatives with the major substituent at the
ortho-position of the TZD group and demonstrated their inhibitory
activity against PTP1B.22 In mouse experiments, the most potent
⇑
Corresponding authors. Tel.: +82 32 890 0924; fax: +82 32 890 0647 (I.-O.H.);
tel.: +82 32 860 7683; fax: +82 32 867 5604 (H.C.).
E-mail addresses: iohan@inha.ac.kr (I.-O. Han), hcho@inha.ac.kr (H. Cho).
These authors contributed equally to this work.
Present address: Department of Chemistry, University of Connecticut, 55 North
à
Eagleville Road, Storrs, CT 06269, USA.
0960-894X/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2010.08.130

B. R. Bhattarai et al. / Bioorg. Med. Chem. Lett. 20 (2010) 6758–6763
6759
O
O
O
Me
N
Me
NH
NH
NH
O
Me
Me
N
S
S
O
S
S
Me
O
O
O
O
O
HO
Ciglitazone
Me
Br
Troglitazone
Rosiglitazone
+NH3
+NH2
Na+
O
-
OSO3
O
OH
O
NH
S
N
O
O
+NH2
Pioglitazone
Ertiprotafib
Trodusquemine
O
O
NH
O
N
N
O
O
N
O
F3C
O
S
O
COOH
CF3
A
B
F3C
CF3
HN
N
H
N
O
S
O
O
O
O
O
O
NH
NH
S
O
S
H3C
S O
O
S NH
O
O
O
Br
Br
O
C
D
18l
Figure 1. Thiazolidinedione derivatives and related compounds reported as PPAR-c activators or PTP1B inhibitors.
inhibitor, D, suppressed weight gain and improved lipid-related
blood parameters. Significant improvement of glucose tolerance
was also observed. Compound D also promoted the effect of
as the substrate. The assay results are summarized in Table 1. The
initial set of compounds, 8a–8c and 11a–11d, were substituted at
both the ortho- and para-positions of the central phenyl group with
either identical benzyloxy groups in 8a–8c or different benzyloxy
groups 11a–11d. These compounds exhibited IC50 values from 4
PPAR-c as a transcription activator in a cell-based reporter gene
assay.
In this study, we extended the previous study to TZD derivatives
containing an additional substituent in a para-orientation on the
central phenyl ring anticipating extra effects by the para-substitu-
to 10 lM. Even though the IC50 values were in a narrow range, a
CF3PhCH2O– substituent at the ortho-position resulted in the
lowest IC50 value within the group. Therefore, the ortho-substitu-
ent was fixed at CF3PhCH2O- for the next set of compounds
(18a–18g, 18l).
Among the compounds with benzyloxy-based substituents at
the para-position (18a–18b, 18d–18e), none of the compounds
showed IC50 values lower than parent compounds 11a or 11d.
Among the compounds with benzenesulfoxy substituents at the
para-position (18f–18g), 18f exhibited improved inhibitory po-
ent. Actually most of the precedent TZD series of PPAR-c agonists
contain a major substituent in a para-orientation. The doubly
substituted TZD derivatives were synthesized and tested for
in vitro efficacy against PTP1B. With the promising in vitro inhibi-
tory potency of these new classes of TZDs, the most potent PTP1B
inhibitor, 18l, was tested for in vivo anti-hyperglycemic and anti-
obesity effects.
Benzylidene-2,4-thiazolidinedione derivatives with substitu-
tions on the phenyl ring at ortho and para-positions of the TZD
group were synthesized as depicted in Scheme 1. In every case,
the TZD group was introduced in the last step of the synthesis by
condensation of the benzaldehyde derivatives and TZD in the pres-
ence of piperidine as a base.23 Compounds 8a–8d were prepared in
simple two steps starting from commercially available 2,4-dihy-
droxybenzaldehyde 6. To prepare 10a–10e as precursors for the
synthesis of11a–11f, ortho- and para-substituents were introduced
independently through selective benzylation24 at the 4-hydroxyl
group of 6, followed by alkylation at the 2-hydroxyl group with
appropriate benzyl bromides or ethyl bromoacetate.
tency (IC50 = 2.3 lM) against PTP1B. With the para-substituent
fixed at the toluenesulfoxy group, the CF3-group of the ortho- sub-
stituent was further varied in 18h, 18i and 18j. All the changes of
the ortho-substituents reduced inhibitory potency, implying that
the CF3PhCH2O might be the choice for the ortho-position.
To examine the possibility of further substitution on the central
benzene ring, Br was introduced at C-5 of the central benzene ring
of 8b. The resulting compound (18c) was 6.4-fold more potent
compared to the parent compound 8b. When Br was introduced
at the equivalent position of 18f, the corresponding compound
(18l) showed an improved inhibitory potency with IC50 value of
1.3 lM, 1.8-fold lower than 18f. As the most potent compound in
For other TZD derivatives, the 4-hydroxyl group of 6 was selec-
tively protected by the methoxymethyl (MOM) group before the
introduction of appropriately substituted benzyl groups at the
2-OH of the benzaldehyde.25 The MOM protecting group was then
removed and the resulting free 4-OH group of the benzaldehyde
functionalized with structurally diverse chemicals.
this study, 18l was proven to be 3.9-fold more potent than com-
pound D, previously reported by us as the most potent PTP1B
inhibitor among the ortho-monosubstituted TZD compounds. It is
interesting to note that there is inconsistency in the improvements
of potency due to the brominations from 8b to 18c and from 18f to
18l (Table 1). The latter two compounds differ from the former
ones in having the sulfonic ester moiety between the central and
one of the terminal phenyl groups. This sulfonic ester group seems
The synthesized TZD derivatives were evaluated for their inhib-
itory activity against PTP1B using p-nitrophenyl phosphate (pNPP)

6760
B. R. Bhattarai et al. / Bioorg. Med. Chem. Lett. 20 (2010) 6758–6763
Scheme 1. Reagents and conditions: (a) RPhCH2Cl or RPhCH2Br, K2CO3, DMF or acetone, reflux, 1–3 h; (b) RPhSO2Cl, DIPEA, DMF, 0 °C to rt, 3 h; (c) 2,4-TZD, EtOH, piperidine,
reflux, overnight; (d) R2PhCH2Cl, KI, NaHCO3, CH3CN, rt to 90 °C, 24 h; (e) BrCH2COOEt, K2CO3, DMF, 90 °C, 3 h; (f) NaOH, MeOH, H2O, 70 °C, 1 h; (g) Br2, CH2Cl2, 0 °C to rt, 3 h;
(h) MOMCl, K2CO3, acetone, 0 °C to rt, 6 h; (i) RPhCH2Br, K2CO3, DMF, rt, 1–3 h; (j) THF/HCl, 50 °C, 2 h.
to play a predominant role in the inhibition. It is also worth to note
that 18k showed 2.5-fold increased potency compared with the
compound D by the presence of an additional toluenesulfoxy group
at the para-position.
The inhibitory activity of compound 18l was evaluated against a
broad range of PTPs including TC-PTP, membrane proximal
catalytic domain LAR (LAR-D1), the catalytic domain of SHP-1
(SHP-1cat) and two microbial PTPs, YOP and YPTP1 (Table 2). Com-
pound 18l displayed P10-fold selectivity over LAR-D1, TC-PTP and
YPTP1, and a few-fold selectivity over SHPTP-1cat and YOP. The
exceptionally large selectivity against LAR-D1 is probably due to
the differences in key determinants in substrate recognition be-
tween PTP1B and LAR-D1. In spite of the similarities in the phos-
photyrosine binding pocket, significant variations were observed

B. R. Bhattarai et al. / Bioorg. Med. Chem. Lett. 20 (2010) 6758–6763
6761
Table 1
acted as PPAR agonists. The maximal activation doses of 18l and
D were 1.5 and 4.0 M, respectively and EC50s were 0.34 and
0.87 M, respectively (data not shown). Since 18l and D are deriv-
atives of TZD, we expect that they regulate PPAR- activity rather
than PPAR- or PPAR-ß/d.
Inhibitory effect of TZD derivatives against PTP1B
l
a
l
Compound
IC50
(
l
M)
c
8a
8b
8c
10 0.7
9.0 1.0
8.0 1.0
a
The anti-obesity and anti-hyperglycemic effects of 18l, which
showed the highest potency against PTP1B in in vitro assays was
tested in high fat diet (HFD)-induced diabetic mice (C57BL/6J Jms
Slc male).28 Twenty-four mice (5 wk old after acclimatization for
1 wk) were divided into two groups: 16 mice fed HFD ad libitum
for further 8 wk to develop the HFD-induced diabetes/obesity;
the remaining 8 provided with low fat diet (LFD) to serve as a lean
control group. After 8 wk, the HFD-fed mice were divided into two
groups; one group continued on the HFD as an obesity/diabetic
control group whereas the other group was provided with
HFD + 18l for a further 4 wk. Compound 18l was administered as
a mixture with the food (1.0 g of 18l/kg of diet). The daily uptake
of 18l was approximated as 2.6 mg/day/mouse, equivalent to
78 mg/day/kg of mouse weight. For the lean control group, LFD
was fed throughout the test period.
Glucose metabolism in the mice was examined after 4 wk of a
drug-feeding period. Fasting glucose levels were checked after fast-
ing 6 h, starting from the beginning of the light cycle. The fasting
glucose level of the 18l-fed group was not significantly lower than
the DIO control group (data not shown). Glucose tolerance was
checked right after the measurement of the fasting glucose level.
Upon loading extra glucose (1.0 g/kg of body weight) by intraperi-
toneal injection, the 18l-fed groups exhibited tendency to normal-
ize blood glucose concentration faster than the HFD control group,
although it was not statistically significant (p = 0.37 at 60 min,
p = 0.22 at 90 min, data not shown).
8d
16
1
11a
11b
11c
11d
11f
18a
18b
18d
18e
18f
4.0 0.4
9.0 0.6
9.0 1.0
4.0 0.5
136 27
6.0 1.6
19
12
12
2.3 0.2
6.0 0.5
33
11
14
1
1
1
18g
18h
18i
2
3
1
18j
18c
18k
18l
1.4 0.2
2.0 0.1
1.3 0.2
5.0 0.1b
1.4 0.1c
D
Ertiprotafib
a
Values are the means standard deviations of
two or more experiments.
b
Data reproduced from our previous
publication.22
c
Data reproduced from our previous
publication.28
in the amino acid residues in the proximity of the active sites of
these enzymes.26,27
The LFD-fed lean control mice gained less body weight com-
pared to the HFD-fed mice and the two groups were clearly differ-
ent in external appearance (data not shown). Significant difference
in body weight gain between the HFD control group and 18l-trea-
ted group was observed during the 4 wk test period (Fig. 3). In
addition, there was no significant difference in body weight gain
between the LFD control group and 18l-treated group during the
test period (Fig. 3).
Kinetic study showed a mixed type of inhibition pattern by
compound 18l in contrast to competitive inhibition by compound
D (data not shown). Compound 18l might possibly favor binding
to the second phosphotyrosine binding site present near the active
site of PTP1B. However, it awaits further study to explain these
apparently contradictory results and to elucidate the binding site
of 18l on PTP1B.
In order to gain insight into the biological function of 18l and D,
we examined the effect of 18l and D on trans-activating activity of
PPAR-c. In this assay, activated PPAR binds peroxisome proliferator
There was no significant difference in cumulative food intake
between the HFD control and 18l-treated mice groups during the
hormone response element (PPRE) located in the promoter of a
luciferase gene, thus activates the transcription of the reporter
gene. The activating effect of 18l and D was compared with well-
defined PPAR-c agonists, troglitazone, rosiglitazone and pioglitaz-
one. HepG2 cells were transfected with a PPRE-driven luciferase
reporter construct or the basic luciferase reporter as a negative
control, which lacks PPRE site. Six hours post transfection, troglit-
azone, rosiglitazone, pioglitazone, 18l and D were added to the cul-
ture medium and cells were lysed 24 h later to measure the
luciferase activity and b-galactosidase activity as a transfection
control.
As shown in Figure 2, the compounds 18l and D were found to
activate the transcription of the PPRE-driven luciferase with poten-
cies comparable to those of glitazone series of compounds (troglit-
azone, rosiglitazone, and pioglitazone) indicating that 18l and D
Table 2
Inhibition of PTP1B and other PTPs by the compound 18la
Figure 2. Effect of compound 181 on PPAR-
were transfected with PPAR-reporter gene (PPRE-driven luciferase reporter
construct) and CMV-bGal constructs and then incubated for 24 h with or without
M of test compounds including troglitazone (Tro), rosiglitazone (Rosi), pioglit-
azone (Pio), 18l, and D. After stimulation, cells were harvested and luciferase
activity was measured using luminometer. The luciferase activity was determined
by normalizing transfection efficiency using b-galactosidase activity. Data are
representative of two independent experiments. Error bar indicates SEM.
c transcriptional activities. HepG2 cells
b
a
Compound
IC50
SHP-1cat
3.0 0.1
(
l
M)
PTP1B
TC-PTP
19
LAR-D1
>100
YOP
YPTP1
12
1
l
18l
1.3 0.2
2
3.9 0.1
0
a
Enzymes were prepared or obtained as described in supplementary materials.
Values are the means standard deviations of two or more experiments.
b

6762
B. R. Bhattarai et al. / Bioorg. Med. Chem. Lett. 20 (2010) 6758–6763
Table 4
Effect of 18l in serum concentration of total cholesterol, TG, and NEFA levels, after
4 wk treatmenta
Mice group Total cholesterol (mg/dL) Triglyceride (mg/dL) NEFA (mM)
HFDb
HFD + 18l
HFD + Db
LFDb
152
6
124 16
76 8**
0.71 0.22
0.20 0.03**
0.22 0.02**
0.18 0.01
124 8**
125 7**
78 10**
107
5
65
5
a
Data presented are the mean values SEM; n = 8/group. Significance of the
difference between HFD group and 18l-fed group was calculated by One-way
ANOVA, where ** represents p <0.05.
b
Data for D-fed group and control groups reproduced from our previous
publication.22
Daily uptake of 18l was approximately half of D in weight and 65%
in number of moles. Under these conditions, compounds 18l and D
revealed almost equivalent effects on mouse body weight and li-
pid-related blood parameters, indicating that 18l was superior to
D in body weight control. On the other hand, there was no evidence
that 18l improved glucose tolerance more effectively than D. Upon
loading extra glucose, the 18l-fed groups exhibited tendency to
normalize blood glucose concentration faster than the HFD control
group (p = 0.37 at 60 min, p = 0.22 at 90 min). Compound D signif-
icantly improved glucose tolerance in mice.
Figure 3. Body weight gain during 4 wk of 18l treatment: Five-wk-old mice were
fed HFD for 8 wk, and then divided into two groups (8 mice/group). The 2 groups
were fed HFD (j) or HFD + 18l (s) for four weeks. Compound 18l (0.1% w/w) in HFD
were mixed well and provided with food. The lean control group (N) was fed LFD
throughout the entire 12 wk period. Each point represents the mean value SEM;
n = 8/group. Significance of the difference between HFD group and 18l-fed group
was calculated by One-way ANOVA, where ** represents p <0.05.
Because 18l could act in vivo as a PTP1B inhibitor or a PPAR-
c
activator or both, the observations in this study were compared
with those after the PTP1B-disruption in mice and after the treat-
ment with the glitazone series of drugs. Recently, two independent
laboratories generated PTP1B gene-disrupted mice.29,30 On feeding
HFD, PTP1BÀ/À male mice gained less weight compared to wild-
type male littermates in both laboratories. PTP1BÀ/À male mice,
but not PTP1B+/À mice, exhibited improved glucose tolerance.
However, no difference in the serum concentrations of free fatty
acids (FFA) was observed between PTP1BÀ/À and wild-type mice.
Treatment with rosiglitazone or poiglitazone improved insulin
sensitivity and glucose tolerance in type 2 diabetic patients. Both
of these drugs reduced plasma FFA but only pioglitazone is known
to lower TG. Aside from these beneficial effects, the glitazone series
of drugs are known to cause weight gain. In this study, the DIO
mice treated with 18l were resistant to weight gain, which was
in agreement with the PTP1B depletion in mice, but not with the
glitazone treatment. The 18l-feeding showed a tendency to im-
prove glucose tolerance, but not with statistical significance. Re-
duced serum FFA levels in 18l-treated mice were consistent with
the glitazone treatment, but not with the PTP1BÀ/À depletion. Low-
er TG levels in the serum of 18l-treated mice were partially consis-
tent with the results of glitazone treatment, with the data from
PTP1B depletion being unavailable. The overall observations on
the 18l-treated mice are partially consistent with the effects of
4 wk treatment period (data not shown). Feed efficiency and body
weight gain per calories consumed were calculated for the HFD
control, 18l-treated and LFD control groups. The test compound-
treated group showed significant differences in feed efficiency
compared to the HFD control group (Table 3) revealing that control
of HFD-induced body weight gain in the 18l-treated group was due
to lower feed efficiency.
The Epididymal and Retroperitoneal fat pad deposits were sig-
nificantly lower in 18l-treated mice compared to HFD control
(Table 3). No overt toxicity was observed in body organs such as
liver, kidney and lungs, with no significant difference in the weight
of these organs in the lean control, HFD control and 18l-treated
mice groups (p >0.05, data not shown). This is an important
improvement in this series of compounds considering that com-
pound D caused dark-brownish spots in livers of mice suggesting
toxic effects.
A significantly lower level of total cholesterol, triglyceride (TG)
and non-esterified free fatty acids (NEFA) were found in the serum
of 18l-treated mice compared to HFD control when tested after
overnight deprivation of the food at the end of the drug-feeding
period (Table 4).
The effects of 18l in mice can be compared with those of com-
pound D. Compound 18l was administered as a mixture with the
food and the daily uptake was 2.6 mg/day/mouse or 78 mg/day/
kg of mouse weight. According to our previous report, daily uptake
of D was 4.8 mg/day/mouse or 143 mg/day/kg of mouse weight.22
PTP1B depletion or PPAR-
with PTP1B depletion and the lower FFA levels with PPAR-
c
activation; the reduced weight gain
activa-
c
tion. Poor anti-hyperglycemic effect of 18l is consistent only with
the observations in PTP1B+/À mice.
Table 3
Effect of 18l on body weight and related parametersa
Mice group
Body weight gain (g)
Feed efficiency
Epididymal fat (g)
Retroperitoneal fat (g)
(wt gain/kcal  100)
HFDb
HFD + 18l
HFD + Db
LFDb
4.88 0.46
2.00 0.62**
2.16 0.29**
1.22 0.54
1.38 0.11
0.57 0.17**
0.68 0.09**
0.59 0.09
1.87 0.08
1.29 0.20**
1.27 0.17**
0.49 0.04
0.69 0.06
0.43 0.08**
0.42 0.07**
0.11 0.02
a
The obese and lean control groups were fed HFD or LFD, containing 45% and 10% of the calories from fat, respectively, for 12 wk. The
test group (HFD + 18l) was fed a HFD for 8 wk, and then a HFD mixed with 18l for 4 wk. All values are the mean values SEM; n = 8/
group. Significance of the difference between the HFD group and 18l-fed group was calculated by One-way ANOVA, where ** represents
p <0.05.
b
Data for D-fed group and control groups reproduced from our previous publication.22

B. R. Bhattarai et al. / Bioorg. Med. Chem. Lett. 20 (2010) 6758–6763
6763
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In conclusion, Benzylidene-2,4-thiazolidinedione derivatives
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range; the most potent compound (18l) showed an IC50 value of
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1.3
lM. In a cell-based assay, compounds 18l and D were also
found to activate the transcription of PPAR-
c
at 1.0 M concentra-
l
tions with potencies comparable to those of troglitazone, rosiglit-
azone, and pioglitazone. Compound 18l was tested in a DIO
mouse model system at a dose level approximately half of D for
its efficacy as an anti-obesity and/or anti-diabetic agent. At this
dose level, 18l did not significantly improve either fasting glucose
level or glucose tolerance in the DIO/diabetic mice. However, obes-
ity-related effects of 18l in DIO mice were almost equivalent to
twofold higher dose of D. Feeding 18l significantly suppressed
diet-induced weight gain and significantly improved blood param-
eters such as TG, total cholesterol, and NEFA. It is also worth to
note that compound 18l is apparently devoid of toxic effects ob-
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Acknowledgments
Support for this work was provided by Inha University. B. R.
Bhattarai and B. Kafle were recipients of a BK21 fellowship.
22. Bhattarai, B. R.; Bhooshan, K.; Hwang, J.-S.; Deegendra, K.; Lee, S.-M.; Kang, J.-
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Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.bmcl.2010.08.130.
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