Potentiating 1-(2-hydroxypropyl)-2-styryl-5-nitroimidazole derivatives against antibacterial agents: Design, synthesis and biology analysis

Article abstract of DOI:10.1016/j.ejmech.2013.05.004

A series of novel 1-(2-hydroxypropyl)-2-styryl-5-nitroimidazole derivatives had been designed, synthesized, isolated and evaluated as potentiators of antibacterial agents. All these synthesized compounds were determined by elemental analysis, ¹H NMR, and MS. Their biological activities were also evaluated against two Gram-negative bacterial strains: Escherichia coli and Pseudomonas aeruginosa and two Gram-positive bacterial strains: Bacillus thuringiensis and Bacillus subtilis by MTT method as potential FabH inhibitory. The results showed that compound 30 exhibited the most potent E. coli FabH inhibitory activity with IC₅₀ of 4.6 μM. Molecular modeling simulation studies were performed in order to predict the biological activities of the proposed compounds. All compounds have been tested for toxicity by MTT assay on human macrophage.

Full text of DOI:10.1016/j.ejmech.2013.05.004

Accepted Manuscript
Potentiating 1-(2-hydroxypropyl)-2-styryl-5-nitroimidazole derivatives against
antibacterial agents: Design, synthesis and biology analysis
Zhong-Chang Wang, Yong-Tao Duan, Ya-Juan Qin, Peng-Fei Wang, Yin Luo, Qing
Wen, Yong-An Yang, Juan Sun, Yang Hu, Ya-Li Sang, Hai-Liang Zhu
PII:
S0223-5234(13)00304-8
10.1016/j.ejmech.2013.05.004
EJMECH 6182
DOI:
Reference:
To appear in: European Journal of Medicinal Chemistry
Received Date: 8 January 2013
Revised Date: 3 April 2013
Accepted Date: 5 May 2013
Please cite this article as: Z.-C. Wang, Y.-T. Duan, Y.-J. Qin, P.-F. Wang, Y. Luo, Q. Wen, Y.-A. Yang, J.
Sun, Y. Hu, Y.-L. Sang, H.-L. Zhu, Potentiating 1-(2-hydroxypropyl)-2-styryl-5-nitroimidazole derivatives
against antibacterial agents: Design, synthesis and biology analysis, European Journal of Medicinal
Chemistry (2013), doi: 10.1016/j.ejmech.2013.05.004.
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ACCEPTED MANUSCRIPT
Potentiating 1-(2-hydroxypropyl)-2-styryl-5-nitroimidazole
derivatives against antibacterial agents: Design, synthesis
and biology analysis
Zhong-Chang Wang†, Yong-Tao Duan†, Ya-Juan Qin, Peng-Fei Wang, Yin Luo,
Qing Wen, Yong-An Yang, Juan Sun, Yang Hu, Ya-Li Sang, Hai-Liang Zhu*
State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210093,
People’s Republic of China
b
A new series of nove1-(2-hydroxypropyl)-2-styryl-5-nitroimidazole derivatives
had been designed, synthesized, isolated and evaluated as potentiators of against
bacterial agents. Compound 30 exhibited the most potent E. coli FabH inhibitory
activity

ACCEPTED MANUSCRIPT
Potentiating 1-(2-hydroxypropyl)-2-styryl-5-nitroimidazole
derivatives against antibacterial agents: Design, synthesis
and biology analysis
Zhong-Chang Wang†, Yong-Tao Duan†, Ya-Juan Qin, Peng-Fei Wang, Yin Luo,
Qing Wen, Yong-An Yang, Juan Sun, Yang Hu, Ya-Li Sang, Hai-Liang Zhu*
State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210093,
People’s Republic of China
*Corresponding author. Tel. & fax: +86-25-83592672; e-mail: zhuhl@nju.edu.cn
†These two authors equally contributed to this paper.
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Abstract
A series of novel 1-(2-hydroxypropyl)-2-styryl-5-nitroimidazole derivatives had
been designed, synthesized, isolated and evaluated as potentiators of antibacterial
agents. All these synthesized compounds were determined by elemental analysis,
1H-NMR, and MS. Their biological activities were also evaluated against two
Gram-negative bacterial strains: Escherichia coli and Pseudomonas aeruginosa and
two Gram-positive bacterial strains: Bacillus thuringiensis and Bacillus subtilis by
MTT method as potential FabH inhibitory. The results showed that compound 30
exhibited the most potent E. coli FabH inhibitory activity with IC50 of 4.6 ꢀM.
Molecular modeling simulation studies were performed in order to predict the
biological activities of the proposed compounds. All compounds have been tested for
toxicity by MTT assay on human macrophage.
Keywords:
Nitroimidazole derivatives
FabH inhibitors
Antibacterial activities
Cytotoxicity
MTT assay
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1 Introduction䟛
Starting from the traditional antibiotics many antibacterials are known and
commercially available [1]. However, the major obstacle in the antimicrobial drug
therapy has come to be the drug resistance. Therefore, the spread of antibiotic
resistance among pathogenic bacteria has become a serious puzzle for the clinical
management of infectious diseases and has resulted in a clear need for novel
antibacterial agents [2, 3]. To solve this severe medical problem, the urgent task of
seeking out new types of antibacterial agents should be accomplished [4]. In recent
years, diverse targets in key areas of the bacterial cell cycle have been studied and
correlative researches showed the prospect of finding a new approach against the
challenge of drug resistance. Among all the targets, the fatty acid synthase (FAS)
pathway in bacteria is a promising one. Fatty acid biosynthesis (FAB) is an essential
metabolic process for prokaryotic organisms and is required for cell viability and
growth. This pathway has been demonstrated to be essential for bacteria cell survival,
and differs considerably from human FAS pathway [5, 6]. A key enzyme responsible
for initiation of bacterial fatty acid biosynthesis has so far escaped serious attention by
the drug discovery industry. FabH, a β-keto-acyl-ACP synthase, plays an essential and
regulatory role in bacterial FAB [7, 8]. As shown in Fig. 1, FabH catalyzes
condensation reaction between a CoA-attached acetyl group and an ACP-attached
malonyl group, which yields acetoacetyl-ACP as its final product [9].
Nitroimidazoles and their derivatives have been extensively used as antimicrobial
chemotherapeutics and as antiangiogenic hypoxic cell radiosensitizers [10]. Therefore,
nitroimidazole derivatives have attracted considerable attention as they show a
tendency to penetrate and accumulate in regions of bacterium, especially in the
organic synthesis [11, 12]. The 5-nitroimidazole core is the most commonly
antimicrobial drug particularly secnidazole and metronidazole which is accepted as
drug of choice for anti-infectious chemotherapy against bacteria [13]. Importantly, the
toxicology and metabolism of nitroimidazoles have been characterized [14].
Secnidazole is rapidly and completely absorbed after oral administration and has a
longer terminal elimination half-life (17-29 h) than commonly used drugs in this class
[15]. In this case, the treatment with secnidazole is shorter and more effective than the
treatment using other imidazole drugs and the adverse effects are not very drastic [16].
In addition, resistance has been induced in vitro against all commonly used
antibacterial drugs, including different 5-nitroimidazole derivatives, furazolidone,
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albendazole, and quinacrine, [17,18] further demonstrating the need for new
compounds to preempt resistance development. Prior studies suggested that
modifications in the 2-position of the imidazole ring (C2 position) can lead to
effective 5-nitroimidazole derivatives drugs.[19,20] As a result, excellent works have
been published on the activities and pharmacokinetics of 1-(2-hydroxypropyl)-2-
styryl-5-nitroimidazole derivatives and their determination in pharmaceutical is of
great importance [21, 22].
As a part of our search for basic information about the structural requirements for
new antimicrobial activities of an existing drug, we designed and synthesized a series
of novel 1-(2-hydroxypropyl)-2-styryl-5-nitroimidazole derivatives bearing
a
substituted styryl unit directly attached to the C2 position which present their in vitro
antibacterial activity against Escherichia coli (E.coli), Pseudomonas aeruginosa (P.
aeruginosa), Bacillus thuringiensis (B. thuringiensis), Bacillus subtilis (B.subtilis)
In this study, the synthesis, in vitro biological activity, and mode of binding of these
compounds are described, and the structure-activity relationships (SAR) are discussed.
Initial studies are performed by modification of the parent compound to determine if
any of the subunits which comprise the secnidazole 2-substituent display antibacterial
activity. Furthermore, docking simulations were performed using the X-ray
crystallographic structure of the FabH in complex with an inhibitor to explore the
binding modes of these compounds at the active site.
2. Chemistry:
A series of novel 1-(2-hydroxypropyl)-2-styryl-5-nitroimidazole derivatives FabH
inhibitors (22-42) were synthesized following the synthetic pathway depicted in
Scheme 1a. By reacting 1-(2-methyl-5-nitro-1H-imidazol-1-yl) propan-2-ol with the
corresponding different substituted benzaldehydes in the presence of sodium
methoxide in methanol, we achieved the corresponding target compounds in good
yields. The reactions were monitored by thin layer chromatography (TLC) and the
products were purified by recrystallization with ethanol. All of the target compounds
gave satisfactory analytical and spectroscopic data, which in accordance with their
1
depicted structures by H NMR, ESI MS and single crystal X-ray structural analysis.
In addition, these compounds were synthesized for the first time. Furthermore, the
crystal structure of compounds 32, 33 and 34 were determined by single crystal X-ray
diffraction analysis in Fig. 2a, Fig. 2b and Fig. 2c.
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2.1 Molecular Modeling.
The protein structure of the E. coli FabH was downloaded from the PDB
(1HNJ.pdb) [7]. And preprocessed using the Schrodinger Protein Preparation Guide
[23], hydrogen atoms were added to the structure, H-bonds within the protein were
optimized, and the protein was minimized to an rmsd of 0.3 Ǻ. A 9.9 Å sphere of
water molecules was added around the ligand and a short (3ps) dynamics run was
carried out, followed by several cycles of minimization utilizing Quanta/CHARMm.
The entire protein-ligand-water complex was free to move during these calculations
[24].
The binding model of compounds 30 and E. coli FabH was depicted in Fig. 3. The
amino acid residues which had interaction with FabH as well as bond length were
labeled. In the binding mode with the 30 (Fig. 3), the hydroxy and nitro of the
1-(5-Nitro-2-(4-nitrostyryl)-1H-imidazol-1-yl) propan-2-ol forms a hydrogen bond
with the backbone NH of Asn247 (angle O · H-D = 123.7.6o, distance = 2.3 Å),
Arg249 (angle O · H-H = 116.2o, distance = 2. 5 Å), respectively. And the nitro of the
benzene forms a hydrogen bond with the backbone NH of Met207 (angle O · H-N =
141.6o, distance = 2.3 Å). In addition, compound 30 was also nicely bound to FabH
via six charge interactions and one π-π interaction. The end group of Arg36, Arg249
and Asp150 respectively formed six charge interactions with two nitro group, which
was accordant exactly with the previous work of FabH inhibitors [25]. Meanwhile, the
nitrogen atom of nitro group formed a π-π interaction with Phe213. This molecular
docking result, along with the biological assay data, suggested that compound 30 was
a potential inhibitor of FabH.
3. Biological activity
3.1 Antimicrobial activity
Our interest in the secnidazole analogues as an alternative to antibacterial treatment
was facilitated by the fact that not only secnidazole is effective but also the imidazole
ring structure attached by side chain provides an opportunity to carry out various
modifications. For these reasons, a series of novel 1-(2-hydroxypropyl)-2-
styryl-5-nitroimidazole derivatives (22-42) had been designed, synthesized. And
compounds 22-42 were assayed against two Gram-negative bacterial strains: E. coli
and P. aeruginosa and two Gram-positive bacterial strains: B. subtilis and B.
thuringiensis by MTT method. In this assay, the IC50 values of compounds possessing
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sufficiently potent antibacterial activity were shown in Table 1. The results were
compared with that provided by the known antibiotic: Kanamycin under identical
conditions, which showed that most of the synthesized compounds exhibited
significant antibacterial activities.
The results obtained from in vitro antibacterial evaluation of compounds 22-42
against susceptible and resistant strains were moderate. Most compounds exhibited
moderate to good activity against all Gram-positive and Gram-negative strains tested.
Best potent activities in vitro were got for compound 30 against E. coil with
corresponding IC50 36.8 ꢀg/mL superior as compared to the positive control Kanamycin.
In addition, these data suggested that compounds 30, 36, 36 and 33 exhibited
distinguished activities with IC50 values of 36.8, 5.7, 3.4 and 6.1 ꢀg/mL against E.coli,
P. aerꢀginosa, B. subtilis and B. thuringiensis, respectively.
Based on the data obtained, we surveyed a variety of substituents at different
positions on the phenyl ring of these 1-(2-hydroxypropyl)-2-styryl-5-nitroimidazole
derivatives, and found that various substituents of such as halogen, methyl, methoxyl
and nitro group led to distinct antibacterial activities of these target compounds.
Compound 30 with a nitro group on the 4-position of phenyl ring manifested higher
antibacterial activity with IC50 value of 36.8 ꢀg/mL against E. coil than other
compounds, while the simplest compound 22 of this styryl series with a bare phenyl
ring displayed the worst antibacterial activity against E. coil. Substitutions at the
phenyl with one methyl moieties did not improve the activity of compound 35
markedly, nor did halogen substitutions on the phenyl ring (24-28, 32-34, 36, 37, 40).
Toxicity was only very slightly increased by most of these modifications, with the
exceptions of the m-fluorine, and o-fluorine substitutions at the correspondence
position of the phenyl ring, which increased toxicity moderately (25 and 33
respectively) but not to the level attained by the compound 22. Addition of larger side
chains at the phenyl moiety, including m-OMe (31) and N (CH3)2 (38), or larger
naphthalene ring (42), markedly reduced the activity against E. coil, while addition of
p-OMe (23) did not affect antibacterial activity or toxicity. On the other hand,
compound 30 with a nitro group on the 4-position of phenyl ring displayed higher
antibacterial activity with IC50 value of 36.8 ꢀg/mL against E. coil than compounds
with a nitro group on the 2-position (40.3 ꢀg/mL) and 3-position (38.8 ꢀg/mL) of
phenyl ring, while the activity gradient of substituent group on the phenyl ring in
m-position was - NO2 > - Cl >- F > - OCH3. Together, these results illustrate that
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derivatives of 5-nitroimidazole derivatives bearing an olefin directly attached to the
C2 position of the imidazole ring have potent antibacterial activities.
In comparison, we found that these compounds, with bulky and electron-
withdrawing group on the benzene ring (such as NO2, F, Cl, Br), exhibited more
potent antibacterial activities than those have electron-donating substituents (such as
CH3, OCH3). From the above-mentioned analysis, it could be concluded that the
compounds with a bare naphthoic ring (108.4 ꢀg/mL) and nitro or halogen substituted
benzene ring were found to be the most favorable for the antibacterial activity. More
importantly, most of the analogues possess low cytoxicity.
3.2 E. coli FabH inhibitory activity
To generate data concerning the broad spectrum potential of these compounds in
Table 1, the IC50 values of selected compounds against FabH enzymes were
summarized in Table 1. Reference data for Kanamycin had also been included for
comparison with the compounds reported in this study. It was possible that this result
reflects a lack of selectivity and that these compounds inhibit other proteinases. In fact,
we knew that the selectivity of these compounds for E. coli FabH can be modulated
by changing the substitution pattern on the benzaldehyde. This would be the subject
of future communications. While E. coli FabH activities would make a
straightforward interpretation of these results difficult, some trends are evident. For
the majority of the compounds, we found that compounds 30 and 39 with IC50 of 4.6
ꢀM and 5.1 ꢀM were better inhibitors than the positive control Kanamycin with IC50
of 6.3 ꢀM, suggesting that, at least in part, inhibition of proliferation of the these lines
be the result of E. coli FabH inhibition.
3.3 Cytotoxicity
All compounds were evaluated for their toxicity against human macrophage with
the median cytotoxic concentration (CC50) data of tested compounds by the MTT
assay, as showed in Table 1. These compounds were tested at multiple doses to study
the viability of macrophage.
Further more, after cells had been cultured for 24 h, morphological anomalies in
macrophage exposed to different concentration compound 41 (2.5, 10, 40, 160 ꢀg/mL)
showed nothing different from morphological in control under phase contrast
microscope (Fig. 4).
As shown in Table 1, 21 compounds demonstrated almost no cytotoxic activities in
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vitro against macrophage.
4. Conclusion:
A series of novel 1-(2-hydroxypropyl)-2-styryl-5-nitroimidazole derivatives have
been designed and synthesized by reaction of 1-(2-methyl-5-nitro-1H-imidazol-1-yl)
propan-2-ol with the corresponding different substituted benzaldehydes. These
compounds showed a very interesting profile for their inhibitory activities against E.
coli, P. aeruginosa, B. subtilis and B. thuringiensis at low concentrations ranging from
micrograms to milligrams per milliliter. Most of them exhibited E. coli FabH
inhibitory activities and almost no toxicity towards morphological. The substitution
pattern at the benzene ring is the main player in controlling the inhibitory power.
Several beneficial substitution patterns were detected, among some 4-nitro, and
2-fluorine, and 2,4-disubstituted 1-(2-hydroxypropyl)-2-styryl-5-nitroimidazoles
incorporating alkyl, alkoxy, aminomethyl, halogen, or nitro moieties. Compound 30
with a nitro group on the 4-position of phenyl ring displayed higher antibacterial
activity with IC50 value of 36.8 ꢀg/mL against E. coil than compounds with a nitro
group on the 2-position (40.2 ꢀg/mL) and 3-position (38.8 ꢀg/mL) of phenyl ring.
Docking simulation was performed to position compound 30 into the E. coli FabH
active site to determine the probable binding conformation and the result indicated
that compound 30 was a potent inhibitor of E. coli FabH. Given the unforeseen
structural differences within the active site of some pathogenic enzymes, the key to
discovering inhibitors with broad-spectrum antibacterial activity lies in a detailed
understanding of the FabH active sites. Further studies on the FabH inhibition ability
of this compound, new structural data were guiding further modifications of the
current series with the hopes of improving both enzymatic inhibition and physical
properties.
5. Experiments
5.1 Materials and measurements
All chemicals used were purchased from Aldrich (USA). All reagents used in
current study were of analytical grade. Thinlayer chromatography (TLC) was
performed on silica gel plates with fluorescent indicator. All analytical samples were
homogeneous on TLC in at least two different solvent systems. Melting points
(uncorrected) were determined on a X-4 MP apparatus (Taike Corp, Beijing, China).
1
All the H NMR and 13C NMR spectra were recorded on a Bruker DPX 300 model
Spectrometer in DMSO-d6 and chemical shifts (δ) were reported as parts per million
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(ppm). ESI-MS spectra were recorded on a Mariner System 5304 Mass spectrometer.
Elemental analyses were performed on a CHN-O-Rapid instrument and were within
±0.4% of the theoretical values.
5.2 General Procedure for the Synthesis of Compounds 22-42.
To a solution of the 1-(2-methyl-5-nitro-1H-imidazol-1-yl) propan-2-ol (12 mmol)
in DMSO (6 mL) at room temperature were added aromatic aldehydes 1-21 (16 mmol)
and sodium methoxide in methanol (12.8 mmol). The reaction mixture was stirred at
room temperature until TLC (VEtOAc/Vhexanes = 1:2) indicated reaction completion
(generally 4-5 h) and poured into ice-water (250 mL). The precipitate formed was
collected, washed three times with distilled water, and dried under vacuum. The crude
products were purified by recrystallization with ethanol, ethyl acetate and acetone
(1:1:0.05) washed by ice-water (25 mL) for three times to give a pure product.
5.2.1. 1-(5-Nitro-2-styryl-1H-imidazol-1-yl) propan-2-ol (22)
1
Light yellow crystals, yield 76.1%, m.p. 77~78 ˚C; H NMR (DMSO-d6, 300
MHz) δ: 8.21 (s, 1H, CH), 7.80~7.75 (m, 3H, ArH, CH), 7.47~7.35 (m, 4H, ArH),
5.02 (d, J=5.4 Hz, 1H, OH), 4.58~4.39 (m, 2H, CH2), 3.89~3.87 (m, 2H, CH), 1.16 (d,
J=6.3 Hz, H, CH3). ESI-MS: 273.20 [M+H]+. Anal. Calcd for C14H15N3O3: C, 61.53;
H, 5.53; N, 15.38; O, 17.56; Found: C, 61.52; H, 5.54; N, 15.37; O, 17.57%.
5.2.2. 1-(2-(4-Methoxystyryl)-5-nitro-1H-imidazol-1-yl) propan-2-ol (23)
Yellow crystals, yield 63.5%, m.p. 64~65 ˚C; 1H NMR (DMSO-d6, 300 MHz) δ:
8.19 (s, 1H, CH), 7.76~7.70 (m, 2H, ArH), 7.24~7.19 (m, 2H, ArH), 6.99 (d, J=8.6 Hz,
2H, CH), 5.00 (d, J=5.4 Hz, 1H, OH), 4.56~4.37 (m, 2H, CH2), 3.87~3.81 (m, 4H,
CH, CH3), 1.15 (d, J =6.2 Hz, 3H, CH3). ESI-MS: 303.11 [M+H]+. Anal. Calcd for
C15H17N3O4: C, 59.40; H, 5.65; N, 13.85; O, 21.10; Found: C, 59.38; H, 5. 67; N,
13.79; O, 21.16%.
5.2.3. 1-(2-(4-Bromostyryl)-5-nitro-1H-imidazol-1-yl) propan-2-ol (24)
Orange crystals, yield 71.2%, m.p. 65~66 ˚C; 1H NMR (DMSO-d6, 300 MHz) δ:
8.21 (s, 1H, CH), 7.77~7.72 (m, 3H, ArH), 7.63 (d, J=8.5 Hz, 2H, CH), 7.44~7.39 (m,
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1H, ArH), 5.00 (d, J=5.4 Hz, 1H, OH), 4.58~4.40 (m, 2H, CH2), 3.90~3.84 (m, 1H,
CH), 1.16 (d, J=6.2 Hz, 3H, CH3). ESI-MS: 352.01 [M+H]+. Anal. Calcd for
C14H14BrN3O3: C, 47.74; H, 4.01; Br, 22.69; N, 11.93; O, 13.63; Found: C, 47.69; H,
4.09; Br, 22.70; N, 11.91; O, 13.61%.
5.2.4. 1-(2-(3-Fluorostyryl)-5-nitro-1H-imidazol-1-yl) propan-2-ol (25)
1
Light yellow crystals, yield 73.4%, m.p. 82~83 ˚C; H NMR (DMSO-d6, 300
MHz) δ: 8.21 (s, 1H, CH), 7.79~7.68 (m, 2H, CH), 7.58~7.40 (m, 3H, ArH),
7.23~7.17 (m, 1H, ArH), 5.01 (d, J=5.4 Hz, 1H, OH), 4.59~4.41 (m, 2H, CH2),
3.88~3.86 (m, 1H, CH). 1.17 (d, J=6.6 Hz, 3H, CH3). ESI-MS: 291.09 [M+H]+. Anal.
Calcd for C14H14FN3O3: C, 57.73; H, 4.84; F, 6.52; N, 14.43; O, 16.48; Found: C,
57.69; H, 4.85; F, 6.51; N, 14.42; O, 16.53%.
5.2.5. 1-(2-(4-Chlorostyryl)-5-nitro-1H-imidazol-1-yl) propan-2-ol (26)
1
Light yellow crystals, yield 62.5%, m.p. 78~79 ˚C; H NMR (DMSO-d6, 300
MHz) δ: 8.21 (s, 1H, CH), 7.82~7.73 (m, 3H, ArH), 7.51~7.37 (m, 3H, ArH, CH),
5.01 (d, J=5.4 Hz, 1H, OH), 4.57~4.45 (m, 2H, CH2), 3.93~3.80 (m, 1H, CH), 1.17 (d,
J=6.3 Hz, 3H, CH3). ESI-MS: 307.56 [M+H]+. Anal. Calcd for C14H14ClN3O3: C,
54.64; H, 4.59; Cl, 11.52; N, 13.65; O, 15.60; Found: C, 54.62; H, 4.60; Cl, 11.51; N,
13.63; O, 15.64%.
5.2.6. 1-(2-(4-Fluorostyryl)-5-nitro-1H-imidazol-1-yl) propan-2-ol (27)
Yellow crystals, yield 68.2%, m.p. 77~78 ˚C; 1H NMR (DMSO-d6, 300 MHz) δ:
8.20 (s, 1H, CH), 7.86~7.74 (m, 3H, ArH), 7.36~7.25 (m, 3H, ArH, CH), 5.00 (d,
J=5.4 Hz, 1H, OH), 4.53~4.44 (m, 2H, CH2), 3.93~3.8 (m, 1H, CH), 1.16 (d, J=2.4
Hz, 3H, CH3). ESI-MS: 291.09 [M+H]+. Anal. Calcd for C14H14FN3O3: C, 57.73; H,
4.84; F, 6.52; N, 14.43; O, 16.48; Found: C, 57.73; H, 4.79; F, 6.53; N, 14.41; O,
16.54%.
5.2.7. 1-(2-(3-Chlorostyryl)-5-nitro-1H-imidazol-1-yl) propan-2-ol (28)
Yellow crystals, yield 64.6%, m.p. 76~77 ˚C; 1H NMR (DMSO-d6, 300 MHz) δ:
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8.22 (d, J=3.0 Hz, 1H, CH), 7.93 (s, 1H, ArH), 7.78~7.68 (m, 2H, CH), 7.48~7.41 (m,
3H, ArH), 5.00 (d, J=5.4 Hz, 1H, OH), 4.60~4.43 (m, 2H, CH2), 3.86 (s, 1H, CH),
1.16 (d, J=6.3 Hz, 3H,CH3). ESI-MS: 307.56 [M+H]+. Anal. Calcd for C14H14ClN3O3:
C, 54.64; H, 4.59; Cl, 11.52; N, 13.65; O, 15.60; Found: C, 54.61; H, 4.60; Cl, 11.51;
N, 13.62; O, 15.66%.
5.2.8. 1-(2-(2-Methoxystyryl)-5-nitro-1H-imidazol-1-yl) propan-2-ol (29)
Yellow crystals, yield 69.4%, m.p. 69~70 ˚C; 1H NMR (DMSO-d6, 300 MHz) δ:
8.19 (s, 1H, CH), 8.08 (d, J=15.8 Hz, 1H, CH), 7.85~7.82 (m, 1H, CH), 7.41~7.30 (m,
2H, ArH), 7.10~7.00 (m, 2H, ArH), 5.02 (d, J=5.4 Hz, 1H, OH), 4.55~4.36 (m, 2H,
CH2), 3.92~3.84 (m, 4H, CH, CH3), 1.16 (d, J=6.3 Hz, 3H, CH3). ESI-MS: 303.01
[M+H]+. Anal. Calcd for C15H17N3O4: C, 59.40; H, 5.65; N, 13.85; O, 21.10; Found:
C, 59.41; H, 5.66; N, 13.84; O, 21.09%.
5.2.9. 1-(5-Nitro-2-(4-nitrostyryl)-1H-imidazol-1-yl) propan-2-ol (30)
Light yellow crystals, yield 67.8%, m.p. 81~ 83 ˚C; 1H NMR (DMSO-d6, 300
MHz) δ: 8.29~8.20 (m, 4H, ArH, CH), 8.05~8.00 (m, 2H, ArH), 7.87 (d, J=15.8 Hz,
1H, CH), 7.61 (d, J=15.8 Hz, 1H, CH), 5.01 (d, J=5.6 Hz, 1H, OH), 4.8 (t, J=5.0 Hz,
2H, CH2), 3.75~3.70 (m, 2H, CH2), 1.15 (d, J=6.2 Hz, 3H, CH3). ESI-MS: 318.08
[M+H]+. Anal. Calcd for C14H14N4O5: C, 52.83; H, 4.43; N, 17.60; O, 25.13; Found:
C, 52.82; H, 4.44; N, 17.61; O, 25.12%.
5.2.10. 1-(2-(3-Methoxystyryl)-5-nitro-1H-imidazol-1-yl) propan-2-ol (31)
1
Yellow crystals, yield 66.1%, m.p. 72~73 ˚C; H NMR (DMSO-d6, 300MHz) δ:
8.21 (s, 1H, CH), 7.77~7.72 (m, 1H, CH), 7.39~7.32 (m, 4H, ArH), 6.99~6.95 (m, 1H,
CH), 5.01 (d, J=5.6 Hz, 1H, OH), 4.59~4.41 (m, 2H, CH2), 3.87~3.75 (m, 4H, CH,
CH3), 1.16 (d, J=6.3 Hz, 4H, CH3, CH,). ESI-MS: 303.11 [M+H]+. Anal. Calcd for
C15H17N3O4: C, 59.40; H, 5.65; N, 13.85; O, 21.10; Found: C, 59.38; H, 5.66; N,
13.86; O, 21.10%.
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5.2.11. 1-(2-(3-Bromostyryl)-5-nitro-1H-imidazol-1-yl) propan-2-ol (32)
1
Light yellow crystals, yield 60.8%, m.p. 67~ 69 ˚C; H NMR (DMSO-d6,
300MHz) δ: 8.21 (s, 1H, CH), 8.06 (s, 1H, ArH), 7.76~7.71 (m, 2H, ArH), 7.57~7.36
(m, 3H, ArH, CH), 5.01 (d, J=5.5 Hz, 1H, OH), 4.60~4.43 (m, 2H, CH2), 3.73~3.68
(m, 2H, CH2). 3.90~3.83 (m, 1H, CH). 1.14 (d, J=9.1 Hz, 3H, CH3). ESI-MS: 352.01
[M+H]+. Anal. Calcd for C14H14BrN3O3: C, 47.74; H, 4.01; Br, 22.69; N, 11.93; O,
13.63; Found: C, 47.75; H, 4.02; Br, 22.68; N, 11.94; O, 13.61%.
5.2.12. 1-(2-(2-Fluorostyryl)-5-nitro-1H-imidazol-1-yl) propan-2-ol (33)
Light yellow crystals, yield 71.6%, m.p. 86~88 ˚C; 1H NMR (DMSO-d6, 300 MHz)
δ: 8.20 (s, 1H, CH), 7.77~7.72 (m, 1H, CH), 7.86 (d, J =16.0 Hz, 1H, CH), 7.50~7.22
(m, 4H, ArH), 5.01 (d, J =5.4 Hz, 1H, OH), 4.59~4.41 (m, 2H, CH2), 3.94~3.81 (m, H,
CH), 1.51 (d, J =6.3 Hz, 3H, CH3). ESI-MS: 291.16 [M+H]+. Anal. Calcd for
C14H14FN3O3: C, 57.73; H, 4.84; F, 6.52; N, 14.43; O, 16.48; Found: C, 57.68; H,
4.86; F, 6.54; N, 14.42; O, 16.50%.
5.2.13. 1-(2-(2-Chlorostyryl)-5-nitro-1H-imidazol-1-yl) propan-2-ol (34)
Yellow crystals, yield 68.2%, m.p. 84~87 ˚C; 1H NMR (DMSO-d6, 300 MHz) δ:
8.20 (s, 1H, CH), 7.77~7.72 (m, 1H, CH), 7.86 (d, J =16.0 Hz, 1H, CH), 7.50~7.22
(m, 4H, ArH), 5.01 (d, J =5.4 Hz, 1H, OH), 4.59~4.41 (m, 2H, CH2), 3.94~3.81 (m, H,
CH), 1.51 (d, J =6.3 Hz, 3H, CH3). ESI-MS: 307.09 [M+H]+. Anal. Calcd for
C14H14ClN3O3: C, 54.64; H, 4.59; Cl, 11.52; N, 13.65; O, 15.60; Found: C, 54.61; H,
4.60; Cl, 11.54; N, 13.65; O, 15.60%.
5.2.14. 1-(2-(4-Methylstyryl)-5-nitro-1H-imidazol-1-yl) propan-2-ol (35)
Yellow crystals, yield 65.6%, m.p. 97~100 ˚C; 1H NMR (DMSO-d6, 300 MHz) δ:
8.18 (s, 1H, CH), 7.85~7.72 (m, 3H, ArH, CH), 7.61~7.32 (m, 3H, ArH, CH), 5.00 (t,
J= 5.4 Hz, 1H, OH), 4.59~4.41 (m, 2H, CH2), 3.94~3.81 (m, H, CH), 2.33 (s, 3H,
CH3,), 1.51 (d, J=6.3 Hz, 3H, CH3). ESI-MS: 287.06 [M+H]+. Anal. Calcd for
C15H17N3O3: C, 62.71; H, 5.96; N, 14.63; O, 16.71; Found: C, 62.73; H, 5.94; N,
14.62; O, 16.72%.
5.2.15. 1-(2-(2-Chloro-6-fluorostyryl)-5-nitro-1H-imidazol-1-yl) propan-2-ol (36)
Light yellow crystals, yield 62.4%, m.p. 70~72 ˚C; 1H NMR (DMSO-d6, 300 MHz)
δ: 8.22 (s, 1H, CH), 7.77~7.72 (m, 1H, CH), 7.50~7.22 (m, 4H, ArH, CH), 5.01 (d,
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J=5.4 Hz,1H, OH), 4.59~4.41 (m, 2H, CH2), 3.94~3.81 (m, H, CH), 1.51 (d, J=6.3 Hz,
3H, CH3). ESI-MS: 325.11 [M+H]+. Anal. Calcd for C14H13ClFN3O3: C, 51.62; H,
4.02; Cl, 10.88; F, 5.83; N, 12.90; O, 14.74; Found: C, 51.58; H, 4.04; Cl, 10.91; F,
5.84; N, 12.91; O, 14.75%.
5.2.16. 1-(2-(2,4-Dichlorostyryl)-5-nitro-1H-imidazol-1-yl) propan-2-ol (37)
1
Orange crystals, yield 66.8%, m.p. 90~92 ˚C; H NMR (DMSO-d6, 300 MHz) δ:
8.22 (s, 1H, CH), 7.77~7.72 (m, 1H, CH), 7.50~7.22 (m, 4H, ArH, CH), 5.01 (d,
J=5.4 Hz, 1H, OH), 4.59~4.41 (m, 2H, CH2), 3.94~3.81 (m, H, CH), 1.51 (d, J=6.3
Hz, 3H, CH3). ESI-MS: 342.06 [M+H]+. Anal. Calcd for C14H13Cl2N3O3: C, 49.14; H,
3.83; Cl, 20.72; N, 12.28; O, 14.03; Found: C, 49.10; H, 3.82; Cl, 20.75; N, 12.30; O,
14.03%.
5.2.17. 1-(2-(4-(Dimethylamino) styryl)-5-nitro-1H-imidazol-1-yl) propan-2-ol
(38)
1
Orange crystals, yield 61.5%, m.p. 46~49 ˚C; H NMR (DMSO-d6, 300 MHz) δ:
8.18 (s, 1H, CH), 7.85~7.72 (m, 3H, ArH, CH), 7.61~7.32 (m, 3H, ArH, CH), 5.00 (t,
J= 5.4 Hz, 1H, OH), 4.59~4.41 (m, 2H, CH2), 3.94~3.81 (m, H, CH), 3.02 (s, 6H,
CH3,), 1.51 (d, J=6.3 Hz, 3H, CH3). ESI-MS: 316.03 [M+H]+. Anal. Calcd for
C16H20N4O3: C, 60.75; H, 6.37; N, 17.71; O, 15.17; Found: C, 60.72; H, 6.38; N,
17.72; O, 15.18%.
5.2.18. 1-(5-Nitro-2-(3-nitrostyryl)-1H-imidazol-1-yl) propan-2-ol (39)
1
Light yellow crystals, yield 63.9%, m.p. 175~177 ˚C; H NMR (DMSO-d6, 300
MHz) δ: 8.64 (s, 1H, ArH), 8.18 (s, 1H, CH), 8.21~8.02 (m, 2H, ArH), 7.91~7.85 (m,
1H, CH), 7.83~7.70 (m, 1H, ArH, CH), 7.68~7.58 (m, 1H, CH), 5.01 (d, J=5.4 Hz, 1H,
OH), 4.59~4.41 (m, 2H, CH2), 3.88~3.86 (m, 1H, CH).,1.17 (d, J=6.6 Hz, 3H, CH3).
ESI-MS: 318.15 [M+H]+. Anal. Calcd for C14H14N4O5: C, 52.83; H, 4.43; N, 17.60; O,
25.13; Found: C, 52.86; H, 4.43; N, 17.61; O, 25.15%.
5.2.19. 1-(2-(2-Bromostyryl)-5-nitro-1H-imidazol-1-yl) propan-2-ol (40)
Yellow crystals, yield 70.1%, m.p. 79~ 81 ˚C; 1H NMR (DMSO-d6, 300 MHz) δ:
8.20 (s, 1H, CH), 7.77~7.72 (m, 1H, CH), 7.86 (d, J =16.0 Hz, 1H, CH), 7.50~7.22
(m, 4H, ArH), 5.01 (d, J=5.4 Hz, 1H, OH), 4.59~4.41 (m, 2H, CH2), 3.94~3.81 (m, H,
13

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CH), 1.51 (d, J=6.3 Hz, 3H, CH3,). ESI-MS: 352.08 [M+H]+. Anal. Calcd for
C14H14BrN3O3: C, 47.74; H, 4.01; Br, 22.69; N, 11.93; O, 13.63; Found: C, 47.72; H,
4.00; Br, 22.70; N, 11.94; O, 13.64%.
5.2.20. 1-(5-Nitro-2-(2-nitrostyryl)-1H-imidazol-1-yl) propan-2-ol (41)
1
Light yellow crystals, yield 65.2%, m.p. 136~ 138 ˚C; H NMR (DMSO-d6, 300
MHz) δ: 8.08 (s, 1H, CH), 7.77~7.72 (m, 1H, CH), 7.86 (d, J=16.0 Hz, 1H, CH),
7.50~7.22 (m, 4H, ArH), 5.01 (d, J=5.4 Hz,1H, OH), 4.59~4.41 (m, 2H, CH2),
3.94~3.81 (m, H, CH), 1.51 (d, J=6.3 Hz, 3H, CH3,). ESI-MS: 318.01 [M+H]+. Anal.
Calcd for C14H14N4O5: C, 52.83; H, 4.43; N, 17.60; O, 25.13; Found: C, 52.82; H,
4.44; N, 17.61; O, 25.12%.
5.2.21. 1-(2-(2-(Naphthalen-2-yl) vinyl)-5-nitro-1H-imidazol-1-yl) propan-2-ol
(42)
Light yellow crystals, yield 65.8%, m.p. 97~ 99 ˚C; 1H NMR (DMSO-d6, 300 MHz)
δ: 8.26 (s, 1H, CH), 7.80~7.75 (m, 7H, ArH, CH), 7.47~7.35 (m, 4H, ArH), 5.02 (d,
J=5.4 Hz, 1H, OH), 4.58~4.39 (m, 2H, CH2), 3.89~3.87 (m, 2H, CH),1.16 (d, J=6.3
Hz, H, CH3). ESI-MS: 323.08 [M+H]+. Anal. Calcd for C18H17N3O3: C, 66.86; H,
5.30; N, 13.00; O, 14.84; Found: C, 66.84; H, 5.29; N, 13.03; O, 14.84%.
5.3 Crystal structure determination
X-ray diffraction studies of compounds 32, 33 and 34 were performed on a
Bruker-APEX diffractometer with a CCD area detector (Mo-Kα=0.71073 Å,
monochromator: graphite) by the ω scan mode. Frames were collected at 293(2) via
u/4-rotation at 10 sper frame (SMART) [26]. The measured intensities were reduced
to F2 and corrected for absorption with SADABS (SAINT-NT) [27]. Corrections were
made for Lorentz and polarization effects. Structure solution, refinement and data
output were carried out with the SHELXTL-NT program package [28].
All the non-hydrogen atoms were refined anisotropically. All the hydrogen atoms
were placed in calculated positions and were assigned fixed isotropic thermal
parameters at 1.2 times the equivalent isotropic U of the atoms to which they were
attached and allowed to ride on their respective parent atoms. The contributions of
these hydrogen atoms were included in the structure factors calculations. The crystal
data, data collection and refinement parameters for the compound 32, 33 and 34 were
14

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listed in Table 2.
5.4 E. coli FabH inhibitory activity
All FabH proteins purified, tagged or tagless can use E.coli holo-ACP as their
substrate. The protein was overexpressed in E.coli DH10B cells using the pET30
vector and purified to homogeneity in three hromatographic steps (Q-Sepharose,
MonoQ, and hydroxyapatite) at 4 ꢀ. The selenomethionine-substituted protein was
expressed cells containing FabH were lysed by sonication in 20 mM Tris, pH 7.6, 5
mM imidazole, 0.5 M NaCl and centrifuged at 20,000 rpm for 30 mins. The
supernatant was applied to a Ni-NTA agarose column, washed, and eluted using a
5-500 mM imidazole gradient over 20 column volumes. Eluted protein was dialyzed
against 20 mM Tris, pH 7.6, 1 mM DTT, and 100 mM NaCl. Purified FabD and
FabHs were concentrated up to 2 mg/mL and stored at -80ꢀ in 20 mM tris, pH 7.6,
100 mM NaCl, 1 mM DTT, and 20% glycerol for enzymatic assay.
In a final 20 ꢀL reaction, 20 mM Na2HPO4, pH 7.0, 0.5 mM DTT, 0.25 mM MgCl2,
and 2.5 ꢀM holo-ACP were mixed with 1 nM FabH (0.5 nM for E. coli FabH, 3 nM
for E. faecalis and H. influenzae FabHs, 10 nM for S. pyogenes FabH, and 20 nM for
Staph aureus FabH), and H2O was added to 16 ꢀL. After 1 min incubation, a 2 ꢀL
mixture of 25 ꢀM acetyl-CoA, 0.5 mM NADH, and 0.5 mM NADPH was added for
FabH reaction for 19 min. The reaction was stopped by adding 20 ꢀL of ice-cold 50%
TCA, incubating for 5 min on ice, and centrifuging to pellet the protein. The pellet
was washed with 10% ice-cold TCA and resuspended with 4 ꢀL of 2 M NaOH. The
3
incorporation of the H signal in the final product was read by liquid scintillation.
When determining the inhibition constant (IC50), inhibitors were added from a
concentrated DMSO stock such that the final concentration of DMSO did not exceed
2% [29].
5.5 Antibacterial activity
IC50 of the test compounds against E.coli,B.thuringiensis,B. subtilis and P. aeruginosa
were determined by a broth microdilution method. They were grown to mid-log phase
in Mueller-Hinton broth and then diluted 10000 fold in the same medium [30].
Afterwards the antibacterial activity of the synthesized compounds was tested against
E. coli, B. thuringiensis, B. subtilis and P. aeruginosa using MH medium
(Mueller-Hinton medium: casein hydrolysate 17.5 g, soluble starch 1.5 g, beef extract
15

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1000 mL). A 10 ꢀL aliquot of the diluted cell suspension (106 to 107 colony forming
units) was used to inoculate each well of a 96-well plate containing 90 ꢀL of MH
broth with the indicated concentration of inhibitors. The plate was incubated at 37 °C
for 24 h [31]. Then 100 ꢀL a series concentration of drug-containing medium were
added into wells to maintain the final concentration of drug as 40, 10, 2.5 and 0.25
ꢀg/mL. After 12 h, bacterial survival was determined by the addition of an MTT
(3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) solution (25 mL of 5
mg/mL MTT in PBS). 4 h later, the medium was discarded and 150 ꢀL DMSO added.
The plates were vibrated for 10 min to make completely dissolution. Optical
absorbance was measured at 490 nm. The experiments were replicated at least three
times to verify the methodology reproducibility when using the above-mentioned
conditions.
5.6 Cytotoxicity
The cytotoxicity test of compounds was measured by the colorimetric MTT assay.
Human macrophage suspension in DMEM medium supplemented with 10% FBS and
1 X antimycotic was added in 96-well microplates at 1.8×104 cells/well. Then, various
concentrations of the test compounds (160, 40, 10, 2.5 and 0.25 ꢀg/mL) dissolved in
distilled 10% DMSO (10 ꢀL) were added to each well. After incubation for 24 h at 37
° C under 5% CO2, 2.5 mg/mL of MTT solution (ꢀL) was added to each well. The
plate was incubated for a further 4 h. Then, the incubation medium was aspirated, and
DMSO (100 ꢀL) was added to solubilize the MTT formazan product. After mixing,
the absorbances at 570 and 655 nm were measured. The difference between
absorbance at 570 and 630 nm was used as an index of the cell viability. The
morphology of the cells was observed using Giemsa stain under Phase contrast
microscope [32, 33].
5.7 Docking simulations
Molecular docking of compounds into the three-dimensional X-ray structure of
FabH was carried out using CDOCKER Dock protocol of Discovery Studio 3.1.
Acknowledgment
The work was financed by a grant (No. J1103512) from National Natural Science
Foundation of China and a grant (No. CXLX12_0047) from Jiangsu Ordinary
University Graduate Students Scientific Research Innovation Plan of China.
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lymphoma 2 and B-cell lymphoma extra large with potent proapoptotic
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Figure Captions
Table 1 Antibacterial activity of 1-(2-hydroxypropyl)-2- styryl -5-nitroimidazole derivatives
(22-42) and their toxicity.
Table 2 Crystallographical and experimental data for compounds 32, 33 and 34
Fig.1. FabH catalyzed initiation reaction of fatty acid biosynthesis.
Fig.2 (a) Crystal structure diagram of compound 32; (b) Crystal structure diagram of compound
33; (c) Crystal structure diagram of compound 34, H atoms are shown as small spheres of
arbitrary radii.
Fig.3. Molecular docking modeling of compound 30 with E. coli FabH: or clarity, only interacting
residues are displayed. (a): 2D model of the interaction between compound 30 and the ATP
binding site. P–sigma bond is displayed as orange lines. H-bonds are displayed as blue and green
dashed lines. (b): 3D model of the interaction between compound 30 and the ATP binding site.
Fig.4. (a) Morphological changes in macrophage at 2.5 ꢀg/mL of compound 41. (b)
Morphological changes in macrophage at 10 ꢀg/mL of compound 41. (c) Morphological changes
in macrophage at 40 ꢀg/mL of compound 41. (d) Morphological changes in macrophage at 160
ꢀg/mL of compound 41.
Scheme 1a
20

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Table 1 Antibacterial activity of 1-(2-hydroxypropyl)-2- styryl -5-nitroimidazole derivatives
(22-42) and their toxicity.
IC50 ( ꢀg/mL) a
E. coli
Gram-negative
Gram-positive
CC50 (ꢀM) b
FabH
Compounds
E.
P.
B.
B.
IC50 (ꢀM)
coli
aeruginosa
thuringiensis
45.6
13.6
56.2
79.2
52.5
28.1
21.4
19.1
11.7
56.2
8.2
subtilis
78.9
12.3
38.0
11.8
79.5
47.1
55.3
10.5
32.5
25.7
15.3
3.4
22
>200
46.1
50.8
120.1
101.8
45.3
86.7
78.6
36.8
180.6
45.4
72.7
56.3
111.4
118.8
111.1
108.1
38.8
63.6
40.3
108.4
47.3
28.0
42.8
15.2
15.0
17.6
24.2
35.0
83.8
5.9
-
1.50
0.56
0.55
1.03
0.98
0.42
0.52
0.48
0.41
1.30
0.62
1.41
0.48
0.86
0.71
0.81
0.68
0.43
0.49
1.09
0.79
-
23
9.5
24
-
25
8.9
26
-
27
-
-
28
29
-
30
4.6
-
31
6.7
32
30.9
39.4
15.4
22.8
5.7
10.8
-
33
60.3
8.6
34
7.5
11.5
78.8
-
35
8.6
8.9
36
6.1
111.8
58.1
56.5
31.1
6.0
37
8.7
18.8
>200
20.6
11.4
72.9
52.2
9.5
-
38
75.0
32.7
11.1
7.4
-
39
5.1
-
40
41
12.3
23.5
8.9
11.0
43.2
6.3
42
42.1
Kanamycin
6.8
a Errors were in the range of (5-10% of the reported values, from three different assays.
b Minimum cytotoxic concentration required to cause a microscopically detectable
alteration of normal cell morphology.
21

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Table 2 Crystallographical and experimental data for compounds 32, 33 and 34
32
33
34
Compound
Empirical formula
Formula weight
Temperature(K)
Crystal system
Space group
a (Å)
C14H14BrN3O3 C14H14FN3O3
C14H14ClN3O3
307.73
352.18
273(2)
291.28
273(2)
273(2)
Monoclinic
P c
Monoclinic
P c
Monoclinic
P c
10.2060(10)
13.4120(12)
10.5874(10)
90.00
11.9002(6)
14.5643(9)
8.8348(5)
90.00
11.4854(17)
15.508(2)
8.7486(13)
90.00
b (Å)
c (Å)
α (°)
90.876(3)
90.00
101.589(2)
90.00
100.007(5)
90.00
β (°)
γ (°)
1449.1(2)
18
1500.01(15)
25
1534.5(4)
20
V (Å)
Z
Dcalcd/g cm-3
θ rang (deg)
F(000)
2.536
1.717
1.698
2.45-25.73
1026
2.24-25.22
775
2.23-25.73
780
13419
14100
14920
Reflections collected
(Rint= 0.0418)
(Rint= 0.0295)
(Rint=0.0492)
2755/0/191
2705/0/207
2918/0/207
Data/restraints/parameters
Absorption coefficient (mm-1)
R1; wR2 [I > 2σ(I)]
R1; wR2 (all data)
12.502
0.193
0.967
0.0644/0.1659
0.0883/0.1845
1.044
0.0721/0.2111
0.0922/0.2338
1.033
0.0504/0.1260
0.0819/0.1438
1.012
GOF
1.037/-0.884
1.114/-0.362
0.257/-0.328
Larg.peak/hole(e. Å)
22

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Fig.1. FabH catalyzed initiation reaction of fatty acid biosynthesis.
c
Fig.2 (a) Crystal structure diagram of compound 32; (b) Crystal structure diagram of
compound 33; (c) Crystal structure diagram of compound 34, H atoms are shown as small
spheres of arbitrary radii.
b
Fig.3. Molecular docking modeling of compound 30 with E. coli FabH: or clarity, only interacting
residues are displayed. (a): 2D model of the interaction between compound 30 and the ATP
binding site. P–sigma bond is displayed as orange lines. H-bonds are displayed as blue and green
dashed lines. (b): 3D model of the interaction between compound 30 and the ATP binding site.
23

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Fig.4. (a) Morphological changes in macrophage at 2.5 ꢀg/mL of compound 41. (b)
Morphological changes in macrophage at 10 ꢀg/mL of compound 41. (c) Morphological changes
in macrophage at 40 ꢀg/mL of compound 41. (d) Morphological changes in macrophage at 160
ꢀg/mL of compound 41.
Scheme 1a
a Reagents and conditions: (a) Sodium methoxide, DMSO, methanol, room temperature;
24

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> 20 Novel 2-styryl-5-nitroimidazole derivatives have been synthesized.
> Their biological activities were evaluated against bacterial
> Most of the compounds showed low toxicity to human macrophage cells.
> Compound 30 showed the most potent and best selective E. coli FabH inhibition.
> Crystal structure of compounds 32, 33 and 34 were determined.