Synthesis, activity, and docking study of phenylthiazole acids as potential agonists of PPARγ

Article abstract of DOI:10.2147/DDDT.S106406

Peroxisome proliferator-activated receptor gamma (PPARγ) is a ligand-mediated transcription factor playing key roles in glucose and lipid homeostasis, and PPARγ ligands possess therapeutic potential in these as well as other areas. In this study, a series of phenylthiazole acids have been synthesized and evaluated for agonistic activity by a convenient fluorescence polarization-based PPARγ ligand screening assay. Compound 4t, as a potential PPARγ agonist with half maximal effective concentration (EC₅₀) 0.75±0.20 μM, exhibited in vitro potency comparable with a 0.83±0.14 μM of the positive control rosiglitazone. Molecular docking and molecular dynamics simulations indicated that phenylthiazole acid 4t interacted with the amino acid residues of the active site of the PPARγ complex in a stable manner, consistent with the result of the in vitro ligand assay.

Full text of DOI:10.2147/DDDT.S106406

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Open ꢄccess FullText ꢄrticle
O ꢀ ꢁ ꢂ ꢁ ꢃ ꢄ ꢅ ꢀ ꢆ ꢇ ꢆ ꢄ ꢀ ꢈ ꢉ
ꢇynthesis, activity, and docking study of
phenylthiazole acids as potential agonists of PPꢄꢀγ
This article was published in the following Dove Press journal:
Drug Design, Development andTherapy
3
0 May 2016
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1
,
ꢅiang Ma *
Abstract: Peroxisome proliferator-activated receptor gamma (PPARγ) is a ligand-mediated
transcription factor playing key roles in glucose and lipid homeostasis, and PPARγ ligands pos-
sess therapeutic potential in these as well as other areas. In this study, a series of phenylthiazole
acids have been synthesized and evaluated for agonistic activity by a convenient fluorescence
polarization-based PPARγ ligand screening assay. Compound 4t, as a potential PPARγ agonist
2
,
Taijin Wang *
1
Min ꢇhi
2
ꢉaoyu Ye
1
Department of ꢃephrology, Kidney
esearch ꢁnstitute, ꢇtate Key
2
with half maximal effective concentration (EC ) 0.75±0.20 μM, exhibited in vitro potency
ꢀ
50
ꢅaboratory of Biotherapy and ꢈancer
ꢈenter/ꢈollaborative ꢁnnovation
ꢈenter of Biotherapy,West ꢈhina
ꢉospital,West ꢈhina Medical ꢇchool
of ꢇichuan University, ꢈhengdu,
People’s ꢀepublic of ꢈhina
comparable with a 0.83±0.14 μM of the positive control rosiglitazone. Molecular docking and
molecular dynamics simulations indicated that phenylthiazole acid 4t interacted with the amino
acid residues of the active site of the PPARγ complex in a stable manner, consistent with the
result of the in vitro ligand assay.
Keywords: PPARγ, phenylthiazole acids, ligand screening assay, docking study
*
These authors contributed equally
to this work
Introduction
Nuclear receptors (NRs) form a superfamily of ligand-dependent transcription factors
that are involved in diverse pathophysiological processes, including reproduction,
1
,2
development, homeostasis, and immune regulation. This superfamily includes
receptors for thyroid hormones, steroid hormones, retinoids, and vitamin D, as well
3
as a large number of orphan receptors. In the human genome sequence that has been
4
elucidated, ~50 NRs were found to be expressed. A large number of studies have
focused on peroxisome proliferator-activated receptors (PPARs), a subset of these
5
NRs, mainly because of their pivotal roles in energy homeostasis.
6–8
PPARs are regulated by endogenous fatty acids and synthetic ligands. So far,
three subtypes, PPARα, PPARβ/δ, and PPARγ, have been identified, which are differ-
9
entially expressed in a tissue-specific manner. The most extensively studied isoform,
PPARγ, modulates the transcription of genes responsible for adipose differentiation,
glucose homeostasis, and lipid metabolism. Therefore, PPARγ has been considered
ꢈorrespondence: ꢅiang Ma
Division of ꢃephrology, Kidney ꢀesearch
9,10
ꢁ
nstitute, West ꢈhina ꢉospital, West
as a therapeutic target for the treatment of diabetes and dyslipidemia. Furthermore,
thiazolidinediones (TZDs) such as rosiglitazone (RSG) and pioglitazone are high-
affinity ligands and full agonists of PPARγ that have been used in the treatment of
ꢈhina Medical ꢇchool of ꢇichuan
University, ꢃo 37 ꢂuoxue Xiang,
ꢈhengdu 610041, People’s ꢀepublic
of ꢈhina
Tel +86 28 8516 4167
ꢆmail liang_m@scu.edu.cn
1
1
type 2 diabetes mellitus. Although TZDs have adverse effects in clinical use, the use
of these synthetic ligands has increased the understanding of the PPARγ mechanism
of activation and its subsequent biological functions. PPARγ agonists TZDs have
also been potential drug leads to develop potent and safe drug candidates, especially
ꢉaoyu Ye
ꢇtate Key ꢅaboratory of Biotherapy and
ꢈancer ꢈenter, West ꢈhina ꢉospital,
West ꢈhina Medical ꢇchool of ꢇichuan
University, ꢈhengdu 610041, People’s
5
,12–14
antidiabetic drug RSG.
This study describes a series of small-molecule phenylthiazole acids that have
been synthesized and investigated for agonistic activity by a convenient fluorescence
ꢀepublic of ꢈhina
ꢆmail yhy1984_hb@163.com
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Ma et al
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polarization (FP)-based PPARγ ligand screening assay. precipitate was formed. The precipitated solid was collected
Compound 4t, as a potential PPARγ agonist with half maximal by vacuum filtration, washed with water (4×15 mL), ethanol
effective concentration (EC ) 0.75±0.20 μM, exhibited (2×10 mL), and ether (2×10 mL), and finally dried in vacuo
5
0
comparable potency to a 0.83±0.14 μM of the positive RSG at 40°C for 24 hours.
control. Docking studies indicated that the phenylthiazole acid
derivative 4t interacted with the amino acid residues of the ꢂeneral procedure for the synthesis of
active site of the PPARγ complex in a stable manner, in which phenylthiazole acids
results are consistent with those of the in vitro ligand assay.
A mixture of phenylthiazol-2-amines (3.5 mmol) and suc-
cinic anhydride or diglycolic anhydride or thiodiglycolic
anhydride (3.5 mmol) in dimethylformamide (15 mL) was
added to pyridine (3.5 mmol) and stirred overnight at room
Materials and methods
ꢈhemical synthesis
Analytical grade chemical reagents were purchased from temperature. The solution was poured into a volume of a
Chengdu Changzheng Chemical Factory (Sichuan, People’s water/ice mixture and acidified with 1 M HCl. The pre-
Republic of China). Thin-layer chromatography was per- cipitated solids that were formed were collected by vacuum
formed on 0.20 mm silica gel 60 F254 plates (Qingdao Ocean filtration, washed with water (4×15 mL), ethanol (2×10 mL),
Chemical Factory, QingDao, People’s Republic of China). and ether (2×10 mL), and finally dried in vacuo at 40°C for
1
Proton nuclear magnetic resonance ( H NMR) spectra were 24 hours (Supplementary Materials).
recorded at 400 MHz on a Varian spectrometer model Gemini
4
00 and reported in parts per million (ppm). Chemical shifts FP-based PPꢄꢀγ ligand screening assay
(δ) are quoted in ppm relative to tetramethylsilane as internal A PPARγ Ligand Screening Assay Kit provided a convenient
16–18
standard, where (δ) tetramethylsilane =0.00 ppm. The mul- FP-based single step assay for screening PPARγ ligands.
tiplicity of the signal is indicated as s, singlet; d, doublet; t, In this assay, a ligand of PPARγ is conjugated to fluorescein
triplet; q, quartet; and m, multiplet, defined as all multipeak and is used as the displacement probe. Ligands, agonists, and
signals where overlap or complex coupling of signals makes antagonists of PPARγ will displace the fluorescent probe, lead-
definitive descriptions of peaks difficult. Mass spectra were ing to a decrease in FP. The PPARγ Ligand Screening Assay
obtained using a Q-TOF Premier mass spectrometer utilizing Kit is a robust assay with a Z′ of 0.81 and has a dynamic range
electrospray ionization (Waters Quattro Premier XE, Milford, of .120 mP units. The assay cocktail was first prepared
MA, USA). The purity of compounds was determined to (including FP Assay Buffer, PPARγ FP Assay Fluorescent
be $97% by high-performance liquid chromatography Probe, and human recombinant PPARγ), and each concentra-
analysis with a photodiode array detector (Waters, Milford, tion of ligand was assayed in duplicate. The plate was covered
MA, USA) and an Atlantis C18 chromatographic column with the plate cover supplied with the kit and incubated for
2
(
150×4.6 mm , id 5 μm; Waters).
60–90 minutes at room temperature. The plates were then read
at excitation and emission wavelengths of 470 and 530 nm,
respectively. The Z′-factor for the PPARγ Ligand Screening
Assay Kit was determined to be 0.81. Results were calcu-
ꢂeneral procedure for the synthesis of
α-bromoacetophenones
Copper (II) bromide (19.5 mmol) was added to a solution of lated by FP of a formula (polarization mP =1,000× (I − I )/
║
┴
acetophenones (6.5 mmol) in anhydrous ethyl acetate (25 mL) (I + I )), and the IC was calculated by the mP-concentration
║
┴
50
and chloroform (25 mL), and the mixture was stirred at 65°C displacement curve according to the kit protocol (Cayman).
for 0.5 hours. The reaction was then extracted with chloroform
(40mL)andthecombinedorganiclayerwaswashedwithwater Molecular docking
(
2×10 mL) and brine (2×10 mL). The solvent was removed to The crystal structure (PDB: 4AME) of PPARγ bound to RSG
15
obtain the crude product without further purification.
was used as the docking template. The protein structure was
processed by Discovery Studio 3.1 (BIOVIA, San Diego, CA,
USA). The chain containing the bound ligand was chosen, and
other ligands were deleted. Furthermore, the water molecules
ꢂeneral procedure for the synthesis of
phenylthiazol-2-amines
Thiourea (4.51 mmol) was added to a solution of were also eliminated. Compounds 4a, 4h, 4i, and 4t weredocked
α-bromoacetophenones (4.3 mmol) in anhydrous ethanol intotheligandbindingdomainusingAutoDock4.2(TheScripps
19
(
10 mL) and the mixture was refluxed for 2 hours. The reac- Research Institute, La Jolla, CA, USA). AutodockTools 1.4.6
tion was allowed to cool to room temperature when a color wasimplementedtobuildtheautogridbox. Thegridcenterwas
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Phenylthiazole acids as potential PPꢄꢀγ agonists
set based on the known ligand, and the grid contained 40×48×54 of TIP3P molecules, and periodic boundary conditions were
autogridpointswith0.375Åspacing.Thenumberofindividuals applied in all directions. The distance between the protein
+
inthepopulationwas150,andthemaximumnumbersofenergy and the box edge was 10 Å. Na counterions were added by
evaluations and generations were 25 million and 27,000, respec- replacing solution to ensure the overall charge neutrality of
tively. Lamarckian GA (4.2) was used to search energetically the simulated system. The steepest descent algorithms were
supported binding modes. In addition, 100 docked poses were implemented for energy minimization with 50,000 steps.
generated, with all settings not mentioned left at their default A restraining simulation was performed by fixing the position
values. In order to obtain further refined information about the of the protein and ligand, heating to 300 K, and equilibrat-
interactions between protein residues and agonists, molecular ing for 100 ps. A 200 ps isothermal-isobaric ensemble and
2
0,21
simulations were performed.
a 25 ns MD were performed in sequence. In carrying out the
MD simulations, the particle mesh Ewald method for long-
range electrostatics, the Lincs algorithm for covalent bond
Molecular dynamics simulations
The binding model of compound 4t and the X-ray struc- constraints, a 14 Å cutoff for van der Waals interactions, and
ture of PPARγ in complex with RSG were prepared for a 12 Å cutoff for Coulomb interactions were all applied.
molecular dynamics (MD) simulations. MD simulations were
Results and discussion
Center, Columbus, OH, USA) with the Amber99sb force ꢈhemistry
performed using GROMACS 4.5.5 (Ohio Supercomputer
22
field. Compound 4t and RSG were parameterized with gen- The preparation of a library of phenylthiazole acid deriva-
eral AMBER force (GAF) parameters and AM1-bond charge tives has been performed in a tandem three-step sequence
corrections (BCC) charges by Antechamber python parser from commercially available acetophenones as described
23
15
interface. The system was surrounded by a cubic water box in Figure 1. Treatment of 1 with copper (II) bromide in
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Figure 1 ꢇynthesis of phenylthiazole acids.
Notes: ꢀeagent and conditions: (a) ꢈuBr , ꢆtOꢄc/ꢈꢉꢈl3 (v:v=1:1), reflux; (b) thiourea, EtOH, reflux; (c) succinic anhydride or diglycolic anhydride or thiodiglycolic
2
anhydride, pyridine, DMF, rt; then HCl.
Abbreviations: DMF, dimethylformamide; rt, room temperature.
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a mixture of ethyl acetate and chloroform as valid solvent unable to promote agonistic activity (methyl phenylthiazole
afforded α-bromoacetophenones 2. The pivotal intermediate 4f, 4o, 4u, and 4v), which indicated that the small steric hin-
phenylthiazol-2-amines 3 were synthesized via a simple drance of thiazole was favorable for agonist potency. Between
reaction of thiourea and appropriate 2 in refluxed ethanol. The biphenyl derivatives 4o and 4t, thesulfuratomoftheacidchain
condensation of 3 with different anhydrides was carried out in significantly improved the agonistic effects compared with the
the presence of pyridine and acidified with diluted hydrochloric oxygen atom. Additionally, the p position of the phenyl group
acid (1 M) to give the corresponding phenylthiazole acids in 4t exhibitedpotentialactivitybecauseofstructuralsimilarity
24
(
4a–v). Following this stage, all final products were fully ana- to the tail group of RSG, identified by the subsequent molecular
lyzed and characterized by nuclear magnetic resonance, mass docking studies and dynamic simulation.
spectroscopy, and high-performance liquid chromatography
before being submitted for biological screening.
Molecular docking
Primarily, the binding mode of RSG has been analyzed
FP-based PPꢄꢀγ ligand screening assay
according to the X-ray structure of the PPARγ complex. The
The agonistic potency of 22 small-molecule phenylthiazole TZD of RSG forms a H-bonding interaction with the three
acids was assessed using a convenient FP-based PPARγ amino acid residues of Tyr473 (2.6 Å), His323 (3.2 Å), and
25,26
ligand screening assay.
Here, RSG as a PPARγ agonist Ser289 (2.2 Å). The hydrophobic tail of RSG interacts with
was chosen as a positive control. As shown in Figure 2, the residues of Leu330, Val339, Ile341, Leu353, Phe363,
four compounds (4a, 4h, 4i, and 4t) were found to exhibit Met364, and Phe368. Therefore, docking poses with a simi-
potential agonistic activity at a concentration of 10.0 μM. lar binding mode and low binding energy were chosen for
Among them, compound 4t showed the most potent effects the study. In Table 2, the in vitro agonistic activity and the
of FP, comparable with RSG.
molecular properties showed good correlation. The potent
On the basis of primary screening, four selected phe- compounds displayed high values of AlogP and LogD, which
nylthiazole acids (4a, 4h, 4i, and 4t) were further investi- proved useful for selecting the phenylthiazoles for predicting
gated. As shown in Table 1, the four compounds possessed molecular properties. A redocking experiment was performed
remarkable agonistic activity on PPARγ. As anticipated, to identify whether the complex could be used for the docking
compound 4t exhibited the greatest agonistic activity on study. The root mean square deviation (RMSD) was 0.9 Å,
PPARγ (EC =0.75±0.20 μM), compared with that of RSG ie, sufficient for the docking template.
5
0
(
EC =0.83±0.14 μM).
The binding energy of RSG was −9.09 kcal/mol, while
5
0
Among the 22 small-molecule phenylthiazole acid deriva- that of 4t was −9.47 kcal/mol. There was a difference rela-
tives (4a–f and 4g–v), thelongchainfattyacidgroupwasfound tionship between the in vitro PPARγ agonistic activity and
to contribute most to the agonist potency (4h, 4i, 4t . 4a). biological activity and the binding energy to PPARγ of 4t,
The introduction of methyl substitution in the thiazole ring was and because the receptor was adjusted significantly to the
1
1
1
1
1
60
55
50
45
40
4a
4b 4c 4d 4e 4f 4g 4h 4i 4j 4k 4l 4m 4n 4o 4p 4q 4r 4s 4t 4u 4v RSG
Compounds
Figure 2 Fluorescence polarization (FP)-based PPꢄꢀγ ligand screening assay of phenylthiazoles.
Note: ꢀesults were mean ± ꢇD of two independent experiments.
Abbreviations: PPꢄꢀγ, peroxisome proliferator-activated receptor gamma; RSG, rosiglitazone.
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Phenylthiazole acids as potential PPꢄꢀγ agonists
Table 1 ꢆꢈ s of phenyl thiazole acids in FP-based PPꢄꢀγ ligand MD simulations
50
screening assay
Due to the fact that the potential ligand-induced conforma-
tional changes were not fully taken into consideration in the
docking study, the MD simulations were performed on the
RSG/4t-PPARγ complex to check whether they were stable in
aqueous solution and if any induced fit occurred. Therefore,
the RMSDs of RSG and 4t were analyzed to assess the degree
of the conformation drift. In the simulation of RSG-bound
PPARγ, the RMSD of RSG was ~,1 Å (Figure 4A). It was
reasonable to suppose that the pose of the RSG-PPARγ com-
plex was taken from the crystal structure and its conformation
was relatively stable. Unlike RSG-bound PPARγ, the RMSD
of 4t was stable after 10 ns simulations (Figure 4B). Com-
pared with the initial docking pose of 4t, the structure closed
to the helix and formed the stronger H-bonding interaction
with the nearest residues in the stable phases (Figure 5A).
At t 25 ns, the carboxylate group of 4t formed a H-bonding
interaction with His449 (2.0 Å), His323 (2.0 Å, 2.7 Å), and
Ser289 (2.6 Å). In addition, its hydrophobic tail fully con-
tacted a surface formed by Leu330, Phe368, Met364, Ile341,
Val339, Phe282, Ile281, and Leu353.
Compounds
Chemical structure
EC50 (μM)
5.21±1.13
4
a
S
NH
N
O
O
OH
H C
3
4
h
S
4.50±0.59
NH O
N
O
OH
H CO
3
4
4
i
S
3.53±0.32
0.75±0.20
CI
NH
O
N
OH
O
O
t
S
NH S
N
OH
O
O
RSG
S
0.83±0.14
O
N
N
NH
O
O
Notes:ResultswerecalculatedbyfluorescencepolarizationofamoleculemP=1,000×
I − I )/(I + I ) and ꢁꢈ was calculated by mP-concentration displacement curve.
(
║
┴
║
┴
50
Abbreviations: ꢆꢈ , half maximal effective concentration; FP, fluorescence
50
polarization; PPARγ, peroxisome proliferator-activated receptor gamma; RSG,
rosiglitazone.
In order to predict binding affinities in stable phases, 4t
in these conformations was redocked into the active site. The
binding energy of the pose whose RMSD value was among the
lowest in the 100 docking poses was retained (Figure 5B). At
presence of the ligand, RSG was better able to bind in the
current phase. Among the four agonists (4a, 4h, 4i, and 4t),
compound, 4t exhibited the lowest binding energy and the
highest activity. The carboxylate group of 4t interacted with
residues of Tyr473 (2.0 Å), His323 (3.2 Å), His449 (3.5 Å),
and Ser289 (1.9 Å) to form hydrogen bonds to the PPARγ
active sites, and its hydrophobic tail was encompassed by
a surface formed from Leu330, Phe368, Met364, Ile341,
Val339, Phe282, Ile281, and Leu353. Additionally, the N
atom of the amide group of 4t formed a H-bonding interaction
with the Cys285 (2.1 Å) of the PPARγ complex (Figure 3A).
However, the other three agonists only interacted with part of
the abovementioned amino acid residues (Figure 3B–D).
25 ns, the lowest value of RMSD was 0.71 Å, and the corre-
sponding binding energy of the pose was −9.47 kcal/mol. The
result indicated that 4t could bind to the active site of PPARγ,
consistent with the data of the in vitro screening assay.
Conclusion
PPARγ modulates the transcription of the genes responsible
for adipose differentiation, glucose homeostasis, and lipid
metabolism and has been considered as a therapeutic target
for the treatment of diabetes and dyslipidemia. In this study,
we describe 22 phenylthiazole acid derivatives that have
been synthesized and evaluated for agonistic activity and to
which an easy, a quick, and a commercial FP-based PPARγ
ligand screening assay was applied to obtain in vitro data
for the primary structure–activity relationship study. Among
the derivatives tested, a potent PPARγ ligand 4t exhibited
comparable agonistic activity to RSG. Docking and dynamics
simulation studies showed that 4t docked in a stable man-
ner to the active site of the PPARγ complex, and the result
was consistent with that of the in vitro ligand assay. Further
chemical modifications of 4t, as well as studies of in vivo
activity and reaction mechanisms, are in progress.
Table 2 The molecular properties and binding energy of selected
phenylthiazole acids
Compounds Molecular properties
PSA ALogP LogD
Binding
energy
Solubility
4
4
4
4
a
i
110.35 0.752
119.59 0.124
128.82 −0.378
135.66 1.901
0.806
0.263
−4.18
−3.92
−0.255 −3.555
−6.24
−5.97
−5.68
−9.47
−9.09
h
t
1.98
−6.33
−4.009
RSG
96.82
3.268
3.268
Abbreviations: PSA, polar surface area; RSG, rosiglitazone.
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Figure 3 The binding modes of agonists with PPꢄꢀγ. Orange and cyans colors represented ꢀꢇꢂ and other agonists, respectively.
Notes: ꢉ-binding interactions of ꢀꢇꢂ and other agonists were shown in orange and cyans dotted line, respectively. (A) 4t and ꢀꢇꢂ, (B) 4a and ꢀꢇꢂ, (C) 4i and ꢀꢇꢂ, and
D) 4h and ꢀꢇꢂ.
Abbreviations: PPꢄꢀγ, peroxisome proliferator-activated receptor gamma; RSG, rosiglitazone.
(
ꢀꢁꢂ
ꢀꢁꢂ
$
%
ꢀꢁꢃꢄ
ꢀꢁꢃ
ꢀ
ꢁꢀꢄ
ꢀ
ꢀ
ꢄꢅꢀꢀꢀ
ꢃꢀꢅꢀꢀꢀ ꢃꢄꢅꢀꢀꢀ ꢂꢀꢅꢀꢀꢀ ꢂꢄꢅꢀꢀꢀ
ꢀ
ꢄꢅꢀꢀꢀ
ꢃꢀꢅꢀꢀꢀ ꢃꢄꢅꢀꢀꢀ ꢂꢀꢅꢀꢀꢀ ꢂꢄꢅꢀꢀꢀ
7LPHꢀꢁSVꢂ
7LPHꢀꢁSVꢂ
Figure 4 The ꢀMꢇD of ligands from the starting structure during 25 ns MD simulations.
Notes: (A) PPꢄꢀγ in complex with ꢀꢇꢂ and (B) PPꢄꢀγ in complex with 4t.
Abbreviations: RMSD, root mean square deviation; MD, molecular dynamics; PPARγ, peroxisome proliferator-activated receptor gamma; RSG, rosiglitazone.
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Phenylthiazole acids as potential PPꢄꢀγ agonists
Figure 5 The binding modes of 4t.
Notes: (A) The binding modes of 4t in binding site of PPꢄꢀγ obtained from ꢄutodock docking (cyans), 21 ns (slate), 22 ns (gray), 23 ns (magenta), 24 ns (violet), and 25 ns
yellow). (B) The binding mode of 4t obtained after MD simulations.
Abbreviations: PPꢄꢀγ, peroxisome proliferator-activated receptor gamma; MD, molecular dynamics.
(
1
3. Ohashi M, Gamo K, Oyama T, Miyachi H. Peroxisome proliferator-
Acknowledgments
activated receptor gamma (PPARγ) has multiple binding points that
accommodate ligands in various conformations: structurally similar
PPARγ partial agonists bind to PPARγ LBD in different conforma-
tions. Bioorg Med Chem Lett. 2015;25(14):2758–2762.
4. Ohashi M, Oyama T, Miyachi H. Different structures of the two peroxi-
some proliferator-activated receptor gamma (PPARγ) ligand-binding
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agonist. Bioorg Med Chem Lett. 2015;25(13):2639–2644.
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of thiazole- and indole-based derivatives for the treatment of type II
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This research was supported by the Natural Science Foun-
dation of China (no 81402782) and the China Postdoctoral
Science Foundation (no 2015T80985).
1
Disclosure
The authors report no conflicts of interest in this work.
1
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Supplementary materials
The chemical structure data of reported compounds in this
study are described in full.
2-(2-Oxo-2-((5-(p-tolyl)thiazol-2-yl)
amino)ethoxy)acetic acid (4g)
1
Yield 45.8%. H NMR (DMSO-d , 400 MHz) δ 12.17 (s,
6
1
H), 7.79 (d, J=8.1 Hz, 2H), 7.57 (s, 1H), 7.24 (d, J=8.0
4
-Oxo-4-((5-(p-tolyl)thiazol-2-yl)amino)
Hz, 2H), 4.33 (s, 2H), 4.20 (s, 2H), 2.32 (s, 3H). MS (ESI),
m/z 305.0 [M-H]−.
butanoic acid (4a)
Yield 62.8%. H NMR (DMSO-d , 400 MHz) δ 12.27 (s,
1
6
2
-(2-((5-(4-Methoxyphenyl)thiazol-2-yl)
1
H), 12.15 (s, 1H), 7.77 (d, J=8.0 Hz, 2H), 7.52 (s, 1H), 7.22
(
d, J=8.0 Hz, 2H), 2.68 (t, J=6.4 Hz, 3H), 2.56 (t, J=6.4 Hz, amino)-2-oxoethoxy)acetic acid (4h)
−
1
2
H), 2.30 (s, 3H); MS (ESI), m/z 289.3 [M-H] .
Yield 54%. H NMR (DMSO-d , 400 MHz) δ 12.12 (s, 1H),
6
7
4
3
.83 (d, J=8.8 Hz, 2H), 7.48 (s, 1H), 6.99 (d, J=8.8 Hz, 2H),
.34 (s, 2H), 4.21 (s, 2H), 2.53–2.48 (m, 3H). MS (ESI), m/z
21.0 [M-H]−.
4
-((5-(4-ꢈhlorophenyl)thiazol-2-yl)
amino)-4-oxobutanoic acid (4b)
Yield 72.5%. H NMR (DMSO-d , 400 MHz) δ 12.32 (s,
1
6
2
-(2-((5-(2-ꢈhlorophenyl)thiazol-2-yl)
1
H), 7.90 (d, J=8.4 Hz, 1H), 7.79 (d, J=8.8 Hz, 1H), 7.67
amino)-2-oxoethoxy)acetic acid (4i)
Yield 52%. H NMR (DMSO-d , 400 MHz) δ 12.28 (s, 1H),
(
s, 1H), 7.51–6.48 (m, 2H), 2.69 (t, J=6.8 Hz, 2H), 2.57 (t,
1
−
J=6.8 Hz, 2H); MS (ESI), m/z 309.3 [M-H] .
6
8
.57 (s, 1H), 7.84 (dd, J=7.6, 1.9 Hz, 1H), 7.64 (s, 1H), 7.55
(
dd, J=7.8, 1.4 Hz, 1H), 7.41 (m, 2H), 4.34 (s, 2H), 4.20 (s,
H). MS (ESI), m/z 325.8 [M-H] .
4
-Oxo-4-((5-(4-(trifluoromethyl)phenyl)
−
2
thiazol-2-yl)amino)butanoic acid (4c)
Yield 75.2%. H NMR (DMSO-d , 400 MHz) δ 12.38 (s,
1
6
2
-(2-((5-(4-ꢈhlorophenyl)thiazol-2-yl)
1
H), 8.10 (d, J=8.0 Hz, 2H), 7.85 (s, 1H), 7.79 (d, J=8.4
amino)-2-oxoethoxy)acetic acid (4j)
Yield 48%. H NMR (DMSO-d , 400 MHz) δ 12.21 (s, 1H),
Hz, 2H), 2.70 (t, J=6.4 Hz, 3H), 2.58 (t, J=6.4 Hz, 3H); MS
1
−
6
(
ESI), m/z 343.3 [M-H] .
7
.92 (d, J=8.5 Hz, 2H), 7.72 (s, 1H), 7.50 (d, J=8.5 Hz, 2H),
−
4
.34 (s, 2H), 4.20 (s, 2H). MS (ESI), m/z 325.0 [M-H] .
4
-((5-(3,4-Difluorophenyl)thiazol-2-yl)
amino)-4-oxobutanoic acid (4d)
2
-(2-((5-(3,4-Dichlorophenyl)thiazol-2-yl)
1
Yield 48.5%. H NMR (DMSO-d , 400 MHz) δ 12.34 (s, 1H),
6
amino)-2-oxoethoxy)acetic acid (4k)
Yield 51.8%. H NMR (DMSO-d , 400 MHz) δ 12.31 (s, 1H),
1
2.24 (s, 1H), 7.88–7.93 (m, 1H), 7.77–7.74 (m, 1H), 7.72
1
6
(
s, 1H), 7.48 (q, J=8.4, 10.4 Hz, 1H), 2.69 (t, J=6.4 Hz, 2H),
8.15 (d, J=2.0 Hz, 1H), 7.97–7.82 (m, 2H), 7.70 (d, J=8.4 Hz,
−
2
.57 (t, J=6.4 Hz, 2H); MS (ESI), m/z 311.3 [M-H] .
−
1H), 4.34 (s, 2H), 4.20 (s, 2H). MS (ESI), m/z 359.0 [M-H] .
4
-((5-(ꢃaphthalen-2-yl)thiazol-2-yl)
2-(2-((5-(3,4-Difluorophenyl)thiazol-2-yl)
amino)-4-oxobutanoic acid (4e)
Yield 76.4%. H NMR (DMSO-d , 400 MHz) δ 12.39 (s, 1H), Yield 58%. H NMR (DMSO-d , 400 MHz) δ 12.19 (s, 1H),
amino)-2-oxoethoxy)acetic acid (4l)
1
1
6
6
1
2.26 (s, 1H), 8.00 (d, J=8.4 Hz, 1H), 7.98–7.92 (m, 3H), 7.91 (ddd, J=12.1, 7.9, 1.9 Hz, 1H), 7.76 (s, 2H), 7.50 (dd,
.77 (s, 1H), 7.56–7.50 (m, 2H), 2.71 (t, J=6.4 Hz, 2H), 2.59 J=19.2, 8.6 Hz, 1H), 4.35 (s, 2H), 4.21 (s, 2H). MS (ESI),
7
−
−
(
t, J=6.4 Hz, 2H); MS (ESI), m/z 325.3 [M-H] .
m/z 327.0 [M-H] .
2
-(2-oxo-2-((5-(4-(Trifluoromethyl)
4
2
-((5-(4-ꢈhlorophenyl)-4-methylthiazol-
phenyl)thiazol-2-yl)amino)ethoxy)acetic
-yl)amino)-4-oxobutanoic acid (4f)
1
Yield 54.8%. H NMR (DMSO-d , 400 MHz) δ12.25 (s, 1H), acid (4m)
2.15 (s, 1H), 7.65 (d, J=8.4 Hz, 2H), 7.49 (d, J=8.8 Hz, 2H), Yield 44%. H NMR (DMSO-d , 400 MHz) δ12.26(s,1H),8.62
6
1
1
6
2
.65 (t, J=6.4 Hz, 2H), 2.55 (t, J=6.4 Hz, 2H), 2.46 (s, 3H); (s, 1H), 8.12 (d, J=8.2 Hz, 2H), 7.90 (s, 1H), 7.80 (d, J=8.3 Hz,
−
−
MS (ESI), m/z 323.3 [M-H] .
2H), 4.35 (s, 2H), 4.21 (s, 2H). MS (ESI), m/z 359.0 [M-H] .
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1
814
Drug Design, Development andTherapy 2016:10
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Dovepress
Phenylthiazole acids as potential PPꢄꢀγ agonists
2
-(2-((5-(4-ꢃitrophenyl)thiazol-2-yl)
2-((2-((5-(3,4-Dichlorophenyl)thiazol-2-
amino)-2-oxoethoxy)acetic acid (4n)
Yield 58.7%. H NMR (DMSO-d , 400 MHz) δ 12.30 (s, 1H), Yield 65%. H NMR (DMSO-d , 400 MHz) δ 12.45 (s,
yl)amino)-2-oxoethyl)thio)acetic acid (4s)
1
1
6
6
8
.32 (d, J=8.8 Hz, 2H), 7.18 (d, J=8.8 Hz, 2H), 8.03 (s, 1H), 1H), 8.14 (d, J=2.1 Hz, 1H), 7.87 (d, J=4.0 Hz, 2H), 7.70
−
4
.36 (s, 2H), 4.21(s, 2H). MS (ESI), m/z 336.0 [M-H] .
(d, J=8.5 Hz, 1H), 3.55 (s, 2H), 3.43 (s, 2H). MS (ESI), m/z
−
3
75.0 [M-H] .
2
-(2-((5-([1,1′-Biphenyl]-4-yl)thiazol-2-yl)
2
-((2-((5-([1,1′-Biphenyl]-4-yl)thiazol-2-yl)
amino)-2-oxoethoxy)acetic acid (4o)
1
Yield 62%. H NMR (DMSO-d , 400 MHz) δ 12.18 (s, 1H), amino)-2-oxoethyl)thio)acetic acid (4t)
6
1
8
4
2
.00 (d, J=8.3 Hz, 2H), 7.76 (s, 1H), 7.73 (dd, J=6.9, 3.8 Hz, Yield 72%. H NMR (DMSO-d , 400 MHz) δ 12.28 (s, 1H),
H), 7.48 (t, J=7.6 Hz, 2H), 7.39 (d, J=7.4 Hz, 1H), 4.36 (s, 7.83 (dd, J=7.6, 1.5 Hz, 2H), 7.63 (s, 2H), 7.56 (d, J=7.8 Hz,
H), 4.22 (s, 2H). MS (ESI), m/z 367.1 [M-H] .
6
−
2H), 7.46–7.36 (m, 4H), 3.55 (s, 2H), 3.41(s, 2H). MS (ESI),
m/z 383.1 [M-H]−.
2
-(2-((4-Methyl-5-phenylthiazol-2-yl)
2
-((2-((4-Methyl-5-phenylthiazol-2-yl)
amino)-2-oxoethoxy)acetic acid (4p)
1
Yield 44%. H NMR (DMSO-d , 400 MHz) δ 11.97 (s, 1H), amino)-2-oxoethyl)thio)acetic acid (4u)
6
1
7
.64 (d, J=7.2 Hz, 2H), 7.45 (t, J=7.6 Hz, 2H), 7.34 (t, J=7.4 Yield 65%. H NMR (DMSO-d , 400 MHz) δ 12.26 (s, 1H),
6
Hz, 1H), 4.31 (s, 2H), 4.19 (s, 2H), 2.48 (s, 3H). MS (ESI), 7.64 (d, J=7.6 Hz, 2H), 7.45 (t, J=7.6 Hz, 2H), 7.35 (t, J=7.4
m/z 305.0 [M-H]−.
Hz, 1H), 3.51 (s, 2H), 3.43 (s, 2H), 2.47 (s, 3H). MS (ESI),
m/z 321.0 [M-H]−.
2
-((2-((5-(4-ꢈhlorophenyl)thiazol-2-yl)
2
-((2-((5-(4-ꢈhlorophenyl)-4-
amino)-2-oxoethyl)thio)acetic acid (4q)
1
Yield 62%. H NMR (DMSO-d , 400 MHz) δ 12.42 (s, 1H), methylthiazol-2-yl)amino)-2-oxoethyl)
6
7
3
.91 (d, J=8.5 Hz, 2H), 7.72 (s, 1H), 7.50 (d, J=8.6 Hz, 2H),
.55 (s, 2H), 3.43 (s, 2H). MS (ESI), m/z 340.9 [M-H] .
thio)acetic acid (4v)
Yield 60%. H NMR (DMSO-d , 400 MHz) δ 12.32 (s, 1H),
−
1
6
7
.66 (d, J=8.5 Hz, 2H), 7.51 (d, J=8.5 Hz, 2H), 3.51 (s, 2H),
.42 (s, 2H), 2.47 (s, 3H). MS (ESI), m/z 355.0 [M-H] .
2
-((2-((5-(4-Fluorophenyl)thiazol-2-yl)
−
3
amino)-2-oxoethyl)thio)acetic acid (4r)
1
Yield 68%. H NMR (DMSO-d , 400 MHz) δ 12.41 (s, 1H),
6
7
.93 (dd, J=8.8, 5.7 Hz, 2H), 7.63 (s, 1H), 7.27 (t, J=8.9 Hz,
−
2H), 3.54 (s, 2H), 3.43 (s, 2H). MS (ESI), m/z 325.0 [M-H] .
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