Design, Synthesis and in vitro Antimycobacterial Activities of Isatin-1,2,3-triazole-moxifloxacin Hybrids

Article abstract of DOI:10.1002/jhet.3023

A new class of isatin-1,2,3-triazole-moxifloxacin (MXFX) hybrids 5a–j was designed, synthesized, and screened for their in vitro antimycobacterial activities against Mycobacterium tuberculosis H₃₇Rv and MDR-TB. All the synthesized hybrids (MIC: 0.10–0.78?μg/mL) exhibited excellent activities against MTB H₃₇Rv and MDR-TB, in spite of none of them were more potent than the parent MXFX (MIC: 0.10 and 0.12?μg/mL). Against MTB H₃₇Rv, the most active 5f (MIC: 0.10?μg/mL) was comparable with MXFX and 4 times more potent than RIF (MIC: 0.39?μg/mL). Against MDR-TB, all hybrids were more active than RIF (MIC: 32?μg/mL) and INH (MIC: >128?μg/mL). In particular, hybrid 5e (MIC: 0.10?μg/mL) was comparable with MXFX and 256 and >1,024 times more potent than RIF and INH. Both conjugates 5e and 5f warrant further investigations.

Full text of DOI:10.1002/jhet.3023

Month 2017 Design, Synthesis and in vitro Antimycobacterial Activities of Isatin-1,2,3-
triazole-moxifloxacin Hybrids
b
b
b
Yuan-Qiang Hu,a
* *
Zhi Xu, Min Qiang, and Zao-Sheng Lv
aSchool of Chemistry and Materials Science, Hubei Engineering University, Hubei, People’s Republic of China
bKey Laboratory of Hubei Province for Coal Conversion and New Carbon Materials, Wuhan University of Science and
Technology, Hubei, People’s Republic of China
*
E-mail: chemmedchem@126.com; whmedchem@126.com
Received June 27, 2017
DOI 10.1002/jhet.3023
Published online 00 Month 2017 in Wiley Online Library (wileyonlinelibrary.com).
A new class of isatin-1,2,3-triazole-moxifloxacin (MXFX) hybrids 5a–j was designed, synthesized, and
screened for their in vitro antimycobacterial activities against Mycobacterium tuberculosis H37Rv and
MDR-TB. All the synthesized hybrids (MIC: 0.10–0.78 μg/mL) exhibited excellent activities against
MTB H37Rv and MDR-TB, in spite of none of them were more potent than the parent MXFX (MIC:
0.10 and 0.12 μg/mL). Against MTB H37Rv, the most active 5f (MIC: 0.10 μg/mL) was comparable with
MXFX and 4 times more potent than RIF (MIC: 0.39 μg/mL). Against MDR-TB, all hybrids were more
active than RIF (MIC: 32 μg/mL) and INH (MIC: >128 μg/mL). In particular, hybrid 5e (MIC: 0.10 μg/
mL) was comparable with MXFX and 256 and >1,024 times more potent than RIF and INH. Both conju-
gates 5e and 5f warrant further investigations.
J. Heterocyclic Chem., 00, 00 (2017).
INTRODUCTION
(TB) causes predominately
to first-line anti-TB therapy [7]. However, the emergence
of MTB strains resistant to FQs has already caused great
concern throughout the world. The fourth generation FQs
moxifloxacin (MXFX) demonstrated promising in vitro
and in vivo activities against MTB including MDR-TB
[8–10] and is under phase III clinical trial for the
treatment of TB. It is worth to notice that MXFX also
retains activity against MTB strains with various levels of
FQs resistance [9].
Several series of FQs-isatin hybrids have been screened
for their in vitro and in vivo anti-TB activities, and the
results suggested that the anti-TB activity was greatly
influenced by the linkers between FQs and isatin [11–17].
Our previous study demonstrated that introduction of
1H-1,2,3-triazole linker between FQs and isatin could
increase the activity of these hybrids against MTB H37Rv
and MDR-TB strains, which was exemplified by GTFX-
isatin hybrid 1 [18]. Chemical structures of isatin,
MXFX, and GTFX-isatin hybrid 1 are shown in Figure 1.
Inspired by the above research results and as a
continuous program for seeking for new anti-TB drugs, a
set of 1H-1,2,3-triazole-tethered isatin-MXFX hybrids
was evaluated in this study. Illustration of the design
Tuberculosis
by
Mycobacterium tuberculosis (MTB), threats human being
for thousands of years. According to the World Health
Organization (WHO) 2016 report, TB resulted in 1.4
million deaths and 10.4 million newly clinical cases in a
single year of 2015 [1]. The wide spread of
drug-resistant TB (DR-TB), multidrug-resistant TB
(MDR-TB), and coinfection with HIV, as well as the
emergence of extensively drug-resistant TB (XDR-TB),
and totally drug resistant TB (TDR-TB) has already
alarming the serious problem in TB control [2–5]. Thus,
the serious situation is creating an urgent need to
develop new anti-TB drugs.
Fluoroquinolones (FQs) are the second widest used
antibiotics in clinical with extensive indications for
infections, act by binding two type II bacterial
topoisomerase enzymes, DNA gyrase, and topoisomerase
IV, thereby inhibiting DNA replication and transcription
[5,6]. Moreover, some of them are currently
recommended as the second-line agents by the WHO to
treat primarily in cases involving resistance or intolerance
© 2017 Wiley Periodicals, Inc.

Y.-Q. Hu, Z. Xu, M. Qiang, and Z.-S. Lv
Vol 000
Figure 1. Chemical structures of isatin, moxifloxacin, and 1H-1,2,3-triazole-tethered GTFX-isatin hybrid 1.
strategy for 1H-1,2,3-triazole-tethered isatin-MXFX
hybrids is depicted in Figure 2.
activities against MTB H37Rv and MDR-TB strains by
rapid direct susceptibility test technique [18]. The
MDR-TB strain was resistant to INH, RIF, and
ethambutol. The minimum inhibitory concentration
(MIC) is defined as the minimum concentration of
compound required to give 90% inhibition of bacterial
growth and MICs of the targets were reported in Table 1.
All the synthesized hybrids (MIC: 0.10–0.78 μg/mL)
exhibited promising activities against MTB H37Rv, but
none of them were more active than the parent MXFX
(MIC: 0.10 μg/mL). Conjugate 5f (MIC: 0.10 μg/mL)
was comparable with MXFX and fourfolds more active
than the reference RIF (MIC: 0.39 μg/mL). Against
MDR-TB, all hybrids showed excellent activities with
MIC ranging from 0.12 to 0.5 μg/mL, far more potent
than the references RIF (MIC: 32 μg/mL) and INH
(MIC: >128 μg/mL). In particular, hybrid 55 (MIC:
0.12 μg/mL) was comparable with MXFX and 256 and
>1,024 times more potent than the parent MXFX (MIC:
0.12 μg/mL) and RIF and INH.
RESULTS AND DISCUSSION
Detailed synthetic route of 1H-1,2,3-triazole-tethered
isatin-MXFX hybrids 5a–l is described in Scheme 1.
Isatin, 5-bromoisatin, and MXFX were alkylated with
1,2-dibromoethane and propargyl bromide, respectively,
in the presence of anhydrous potassium carbonate to
provide the corresponding N-(2-bromoethyl)isatins 2a,b
(yield: 56% and 62%) and propargyl MXFX 4 (yield:
69%) via literature methods [18–22]. Treatment of N-(2-
bromoethyl)isatins 2a,b with sodium azide at 60°C yielded
the desired azido precursors 3a,b, which was used together
with 4 for the synthesis of desired 1,2,3-triazole-tethered
hybrids 5a,b (yield: 46% and 48%) in the presence of
Cu(OAc)2 in DMF [18]. Subsequent condensations of
conjugates 5a,b with requisite substituted amine
hydrochlorides in the presence of sodium bicarbonate
formed other hybrids 5c–j (42–65%) [10].
The resistance index (RI: MICMDR-TB: MICMTB H37Rv
)
for the majority targets was around 1, indicating this
kind of hybrids could reduce the cross-resistant to
some extent.
Compared with the parent MXFX (Log P: 1.68), all
hybrids 5a–j (Log P: 1.84–4.30) showed greater
lipophilicity that may improve their permeation properties
toward mycobacterial cell membrane. The hybrids 5a–j
were screened for their in vitro antimycobacterial
In summary, a series of novel 1H-1,2,3-triazole-tethered
isatin-MXFX hybrids were designed, synthesized, and
evaluated for their in vitro antimycobacterial activities
against MTB H37Rv and MDR-TB strains. All the
synthesized hybrids exhibited excellent activities against
MTB H37Rv and MDR-TB. Against MTB H37Rv, the
most active 5f was 4 times more potent than RIF.
Against MDR-TB, hybrid 5e was 256 and >1,024 times
more potent than RIF and INH. Both conjugates 5e and
5f warrant further investigations.
EXPERIMENTAL SECTION
Synthesis. General Procedure for thereparation of 5a,b.
N-(2-azidoethyl)isatins 3a,b and propargyl MXFX 4
(yield: 39%) were prepared via literature methods [18].
To a mixture of N-(2-azidoethyl)isatins 3a,b (1.0 mmol)
and propargyl MXFX 4 (1.0 mmol) in DMF (50 mL),
Cu(OAc)2 (100 mg) was added under N2 atmosphere.
The mixture was allowed to react for 48 h at room
Figure 2. Illustration of the design strategy for 1H-1,2,3-triazole-tethered
moxifloxacin-isatin hybrids. [Color figure can be viewed at
wileyonlinelibrary.com]
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2017
Design, Synthesis and in vitro Antimycobacterial Activities of Isatin-1,2,3-
triazole-moxifloxacin Hybrids
Scheme 1. Synthesis of 1H-1,2,3-triazole-tethered isatin-moxifloxacin hybrids 5a–j.
temperature. After removal of the solvent in vacuo, the
residue was purified by silica gel column chromatography
eluted with DCM to v(DCM):v(MeOH) = 10:1. After
removal of the solvent by evaporation, targets 5a,b (46%
(m, 2H), 6.96–8.65 (6H, m, Ar-H), 15.28 (1H, brs,
COOH). ESI-MS m/z: 734 [M + H]+, 736 [M + 2 + H]+.
Elemental Anal. Calcd (%) for C34H33FBrN7O6: C,
55.59; H, 4.53; N, 13.35; found: C, 55.47; H, 4.52; N,
13.28.
and 48%) were obtained.
1-cyclopropyl-7-((4aR,7aR)-1-((1-(2-(2,3-dioxoindolin-1-yl)
ethyl)-1H-1,2,3-triazol-4-yl)methyl)hexahydro-1H-pyrrolo[3,4-
b]pyridin-6(2H)-yl)-6-fluoro-8-methoxy-4-oxo-1,4-
The general procedure for preparing other targets. To a
solution of substituted amine hydrochlorides (6 mmol) and
sodium bicarbonate (6 mmol) dissolved in water (10 mL)
and methanol (10 mL) was added 5a,b. The reaction
mixture was stirred at room temperature for 24 h. After
removal of the solvent in vacuo, the residue was diluted
with water (20 mL) and stirred for 10 min, and then
filtered. The solid crude product was purified by column
chromatography (silica gel) eluted with DCM to v(DCM):
v(MeOH) = 10:1. After removal of the solvent by
dihydroquinoline-3-carboxylic acid (5a).
Yellow solid,
yield: 46%. Mp: 168–170°C. 1H NMR (400 MHz,
DMSO-d6) δ 1.00–1.61 (m, 9H), 2.05–2.07 (m, 1H),
2.32–2.34 (m, 1H), 2.60–2.62 (m, 1H), 2.76–2.79 (m,
1H), 3.55–3.80 (m, 8H), 4.10–4.14 (m, 3H), 4.61–4.62
(m, 2H), 6.87–8.67 (7H, m, Ar-H), 15.22 (1H, brs,
COOH). ESI-MS m/z: 656 [M + H]+. Elemental Anal.
Calcd (%) for C34H34FN7O6: C, 62.28; H, 5.23; N,
evaporation, targets 5c–l (42–65%) were obtained.
14.95; found: C, 62.11; H, 5.08; N, 14.87.
1-cyclopropyl-6-fluoro-7-((4aR,7aR)-1-((1-(2-(3-
7-((4aR,7aR)-1-((1-(2-(5-bromo-2,3-dioxoindolin-1-yl)ethyl)-
1H-1,2,3-triazol-4-yl)methyl)hexahydro-1H-pyrrolo[3,4-b]
pyridin-6(2H)-yl)-1-cyclopropyl-6-fluoro-8-methoxy-4-oxo-1,4-
(hydroxyimino)-2-oxoindolin-1-yl)ethyl)-1H-1,2,3-triazol-4-yl)
methyl)hexahydro-1H-pyrrolo[3,4-b]pyridin-6(2H)-yl)-8-
methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (5c).
dihydroquinoline-3-carboxylic acid (5b).
Light yellow
Yellow solid, yield: 65%. Mp: 203–205°C. 1H NMR
(400 MHz, DMSO-d6) δ 0.99–1.65 (m, 9H), 2.06–2.07
(m, 1H), 2.30–2.32 (m, 1H), 2.61–2.62 (m, 1H),
2.78–2.80 (m, 1H), 3.57–3.84 (m, 8H), 4.11–4.14
1
solid, yield: 48%. Mp: 154–155°C. H NMR (400 MHz,
DMSO-d6) δ 0.98–1.59 (m, 9H), 2.06–2.07 (m, 1H),
2.31–2.33 (m, 1H), 2.57–2.59 (m, 1H), 2.80–2.81 (m,
1H), 3.57–3.83 (m, 8H), 4.09–4.14 (m, 3H), 4.61–4.63
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Y.-Q. Hu, Z. Xu, M. Qiang, and Z.-S. Lv
Vol 000
Table 1
Structures, lipophilicity, and antimycobacterial activity of compounds 5a–j.
MIC (μg/mL)
MTB H37Rv
Compd.
R1
R2
Log P a
MDR-TBb
5a
5b
5c
5d
5e
5f
5g
5h
5i
5j
MXFX
INH
RIF
O
O
H
Br
H
Br
H
Br
H
Br
H
Br
2.48
3.31
2.87
3.70
3.14
3.96
3.47
4.30
1.84
2.67
1.68
À0.67
3.71
0.39
0.78
0.78
0.78
0.20
0.10
0.39
0.78
0.78
0.78
0.10
0.05
0.39
0.25
0.50
0.25
0.5
0.12
0.25
0.25
0.25
0.5
NOH
NOH
NOMe
NOMe
NOEt
NOEt
NNHCONH2
NNHCONH2
0.5
0.12
>128
32
MXFX, moxifloxacin; MTB, Mycobacterium tuberculosis; MIC, minimum inhibitory concentration; MDR-TB, multidrug-resistant TB.
aThe Log P is calculated with ChemOffice 2014 software.
bMDR-TB: resistant to INH, RIF, and EMB.
(m, 3H), 4.61–4.62 (m, 2H), 6.84–8.65 (7H, m, Ar-H),
13.52 (1H, brs, NOH), 15.26 (1H, brs, COOH). ESI-MS
m/z: 671 [M + H]+. Elemental Anal. Calcd (%) for
C34H35FN8O6: C, 60.89; H, 5.26; N, 16.71; found: C,
15.24 (1H, brs, COOH). ESI-MS m/z: 685 [M + H]+.
Elemental Anal. Calcd (%) for C35H37FN8O6: C, 61.39;
H, 5.45; N, 16.36; found: C, 61.21; H, 5.37; N, 16.31.
7-((4aR,7aR)-1-((1-(2-(5-bromo-3-(methoxyimino)-2-
oxoindolin-1-yl)ethyl)-1H-1,2,3-triazol-4-yl)methyl)hexahydro-
1H-pyrrolo[3,4-b]pyridin-6(2H)-yl)-1-cyclopropyl-6-fluoro-8-
methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (5f).
60.72; H, 5.21; N, 16.63.
7-((4aR,7aR)-1-((1-(2-(5-bromo-3-(hydroxyimino)-2-
oxoindolin-1-yl)ethyl)-1H-1,2,3-triazol-4-yl)methyl)hexahydro-
1H-pyrrolo[3,4-b]pyridin-6(2H)-yl)-1-cyclopropyl-6-fluoro-8-
methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (5d).
Light yellow solid, yield: 51%. Mp: 138–140°C. 1H
NMR (400 MHz, DMSO-d6) δ 0.99–1.59 (m, 9H),
2.04–2.06 (m, 1H), 2.30–2.32 (m, 1H), 2.60–2.61 (m,
1H), 2.80–2.82 (m, 1H), 3.55–3.81 (m, 8H), 4.12–4.13
(m, 3H), 4.26 (s, 3H, NOCH3), 4.61–4.62 (m, 2H),
6.89–8.65 (6H, m, Ar-H), 15.22 (1H, brs, COOH).
ESI-MS m/z: 763 [M + H]+, 765 [M + 2 + H]+.
Elemental Anal. Calcd (%) for C35H36FBrN8O6: C,
55.05; H, 4.75; N, 14.67; found: C, 54.91; H, 4.57; N,
Light yellow solid, yield: 57%. Mp: 183–185°C. 1H NMR
(400 MHz, DMSO-d6) δ 1.00–1.61 (m, 9H), 2.04–2.05
(m, 1H), 2.30–2.31 (m, 1H), 2.57–2.58 (m, 1H),
2.79–2.80 (m, 1H), 3.56–3.79 (m, 8H), 4.12–4.14 (m,
3H), 4.60–4.61 (m, 2H), 6.87–8.67 (6H, m, Ar-H), 13.50
(1H, brs, NOH), 15.30 (1H, brs, COOH). ESI-MS m/z:
749 [M + H]+, 751 [M + 2 + H]+. Elemental Anal. Calcd
(%) for C34H34FBrN8O6: C, 54.48; H, 4.57; N, 14.95;
14.49.
1-cyclopropyl-7-((4aR,7aR)-1-((1-(2-(3-(ethoxyimino)-2-
oxoindolin-1-yl)ethyl)-1H-1,2,3-triazol-4-yl)methyl)hexahydro-
1H-pyrrolo[3,4-b]pyridin-6(2H)-yl)-6-fluoro-8-methoxy-4-oxo-
1,4-dihydroquinoline-3-carboxylic acid (5g). Light yellow
found: C, 54.42; H, 4.53; N, 14.78.
1-cyclopropyl-6-fluoro-8-methoxy-7-((4aR,7aR)-1-((1-(2-(3-
(methoxyimino)-2-oxoindolin-1-yl)ethyl)-1H-1,2,3-triazol-4-yl)
methyl)hexahydro-1H-pyrrolo[3,4-b]pyridin-6(2H)-yl)-4-oxo-
1
1,4-dihydroquinoline-3-carboxylic acid (5e).
Light yellow
solid, yield: 52%. Mp: 156–158°C. H NMR (400 MHz,
1
solid, yield: 59%. Mp: 150–151°C. H NMR (400 MHz,
DMSO-d6) δ 0.98–1.58 (m, 9H), 2.05–2.06 (m, 1H),
2.33–2.34 (m, 1H), 2.78–2.79 (m, 1H), 2.81–2.82 (m,
1H), 3.54–3.76 (m, 8H), 4.10–4.12 (m, 3H), 4.25 (s, 3H,
NOCH3), 4.62–4.63 (m, 2H), 6.71–8.65 (7H, m, Ar-H),
DMSO-d6) δ 1.00–1.60 (m, 12H), 2.03–2.04 (m, 1H),
2.31–2.32 (m, 1H), 2.72–2.74 (m, 1H), 2.80–2.82 (m,
1H), 3.56–3.836 (m, 8H), 4.11–4.12 (m, 3H), 4.41 (q, 2H,
NOCH2CH3), 4.61–4.63 (m, 2H), 6.73–8.65 (7H, m, Ar-
H), 15.22 (1H, brs, COOH). ESI-MS m/z: 699 [M + H]+.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2017
Design, Synthesis and in vitro Antimycobacterial Activities of Isatin-1,2,3-
triazole-moxifloxacin Hybrids
Elemental Anal. Calcd (%) for C36H39FN8O6: C, 61.88; H,
5.63; N, 16.04; found: C, 61.83; H, 5.57; N, 15.93.
7-((4aR,7aR)-1-((1-(2-(5-bromo-3-(ethoxyimino)-2-
oxoindolin-1-yl)ethyl)-1H-1,2,3-triazol-4-yl)methyl)hexahydro-
1H-pyrrolo[3,4-b]pyridin-6(2H)-yl)-1-cyclopropyl-6-fluoro-8-
methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (5h).
compounds in two wells as the positive control of growth
and deionized water instead of the culture in other two
wells as the negative control of growth in the plates. The
plates were covered and sealed, and then incubated at
37°C in a wet box. The positive and negative control
wells should show obvious difference after 3 days. The
MIC was determined by observing the quantity and state
of the cells in each test well by a continuous visual high
magnification system and redetermined 7 days later. The
MIC is defined as the concentration of the compound
required to give complete inhibition of bacterial growth.
Light yellow solid, yield: 43%. Mp: 121–122°C. 1H NMR
(400 MHz, DMSO-d6) δ 1.02–1.68 (m, 12H), 2.05–2.06
(m, 1H), 2.31–2.32 (m, 1H), 2.71–2.73 (m, 1H),
2.81–2.82 (m, 1H), 3.56–3.79 (m, 8H), 4.11–4.13 (m,
3H), 4.43 (q, 2H, NOCH2CH3), 4.60–4.62 (m, 2H), 6.80–
8.67 (6H, m, Ar-H), 15.22 (1H, brs, COOH). ESI-MS m/z:
777 [M + H]+, 779 [M + 2 + H]+. Elemental Anal. Calcd
(%) for C36H38FBrN8O6: C, 55.60; H, 4.93; N, 14.41;
REFERENCES AND NOTES
found: C, 55.47; H, 4.85; N, 14.37.
7-((4aR,7aR)-1-((1-(2-(3-(2-carbamoylhydrazono)-2-
oxoindolin-1-yl)ethyl)-1H-1,2,3-triazol-4-yl)methyl)hexahydro-
1H-pyrrolo[3,4-b]pyridin-6(2H)-yl)-1-cyclopropyl-6-fluoro-8-
methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (5i).
[1] World Health Organization Global Tuberculosis Report 2016
(WHO/HTM/TB/2016.10); World Health Organization: Geneva, 2016.
[2] Xu, Z.; Zhang, S.; Gao, C.; Zhao, F.; Lv, Z. S.; Feng, L. S.
Chin Chem Lett 2017, 2, 159.
Light yellow solid, yield: 42%. Mp: 133–134°C. 1H
NMR (400 MHz, DMSO-d6) δ 1.00–1.61 (m, 9H),
2.07–2.08 (m, 1H), 2.35–2.36 (m, 1H), 2.68–2.69 (m,
1H), 2.77–2.79 (m, 1H), 3.58–3.81 (m, 8H), 4.11–4.13
(m, 3H), 4.61–4.62 (m, 2H), 6.88–8.67 (7H, m, Ar-H),
8.69, 9.00 (s, 2H, CONH2), 12.16 (s, 1H, NNHCO),
15.24 (1H, brs, COOH). ESI-MS m/z: 747 [M + H]+.
Elemental Anal. Calcd (%) for C35H37FN10O6: C, 58.98;
H, 5.23; N, 19.65; found: C, 58.79; H, 5.03; N, 19.47.
7-((4aR,7aR)-1-((1-(2-(5-bromo-3-(2-carbamoylhydrazono)-
2-oxoindolin-1-yl)ethyl)-1H-1,2,3-triazol-4-yl)methyl)
hexahydro-1H-pyrrolo[3,4-b]pyridin-6(2H)-yl)-1-cyclopropyl-6-
fluoro-8-methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid
(5j). Light yellow solid, yield: 44%. Mp: 117–119°C. 1H
NMR (400 MHz, DMSO-d6) δ 0.98–1.59 (m, 9H),
2.05–2.06 (m, 1H), 2.37–2.38 (m, 1H), 2.72–2.74 (m,
1H), 2.80–2.82 (m, 1H), 3.56–3.84 (m, 8H), 4.10–4.13
(m, 3H), 4.60–4.62 (m, 2H), 6.86–8.65 (6H, m, Ar-H),
8.68, 9.01 (s, 2H, CONH2), 12.14 (s, 1H, NNHCO),
15.24 (1H, brs, COOH). ESI-MS m/z: 791 [M + H]+, 793
[M + 2 + H]+. Elemental Anal. Calcd (%) for
C35H36FBrN10O6: C, 53.10; H, 4.58; N, 17.69; found: C,
[3] Hu, Y. Q.; Zhang, S.; Zhao, F.; Gao, C.; Feng, L. S.; Lv, Z. S.;
Xu, Z.; Wu, X. Eur J Med Chem 2017, 133, 255.
[4] Hu, Y. Q.; Xu, Z.; Zhang, S.; Wu, X.; Ding, J. W.; Lv, Z. S.;
Feng, L. S. Eur J Med Chem 2017, 136, 122.
[5] Zhang, S.; Xu, Z.; Gao, C.; Ren, Q. C.; Chang, L.; Lv, Z. S.;
Feng, L. S. Eur J Med Chem 2017, 138, 501-513.
[6] Kerns, R. J.; Rybak, G. W. M.; Vaka, F.; Cha, R.; Grucz, R. G.;
Diwadkar, V. U.; Ward, T. D. Bioorg Med Chem Lett 2003, 13, 1745.
[7] Crofton, J.; Choculet, P.; Maher, D. Guidelines for the Man-
agement of Drug-Resistant Tuberculosis WHO/TB/96–210 (Rev.1);
World Health Organization: Geneva, 1997.
[8] Feng, L. S.; Liu, M. L.; Zhang, Y. B. Chem Res Chin Univ
2012, 28, 61.
[9] Maitre, T.; Petitjean, G.; Chauffour, A.; Bernard, C.; Helali, N.
E.; Jarlier, V.; Reibel, F.; Chavanet, P.; Aubry, A.; Veziris, N.; Antimicrob,
J. Agents Chemother 2017, 72, 2362.
[10] Ruan, Q. L.; Liu, Q. H.; Sun, F.; Shao, L. Y.; Jin, J. L.; Yu, S.
L.; Ai, J. W.; Zhang, B. Y.; Zhang, W. H. Emerg Microbes Infect 2016, 5,
e12.
[11] Sriram, D.; Aubry, A.; Yogeeswaria, P.; Fisher, L. M. Bioorg
Med Chem Lett 2006, 16, 2982.
[12] Sriram, D.; Yogeeswaria, P.; Basha, J. S.; Radhaet, D. R.;
Nagaraja, V. Bioorg Med Chem 2005, 13, 5774.
[13] Pandeya, S. N.; Srirama, D.; Yogeeswari, P.; Ananthan, S.
Chemother 2001, 47, 266.
[14] Zhao, S. H.; Pine, R.; Domagala, J.; Drlica, K. Antimicrob
Agents Chemother 1999, 43, 661.
[15] Feng, L. S.; Liu, M. L.; Zhang, S. Eur J Med Chem 2011, 46,
341.
[16] Wan, Z. L.; Liu, M. L.; Feng, L. S.; Wang, B.; Zheng, X. D.;
Guo, H. Y. Chin J Antibiot 2011, 36, 37.
[17] Nagesh, H. N.; Naidu, K. M.; Rao, D. H.; Sridevi, J. P.; Sriram,
D.; Yogeeswari, P.; Sekhar, K. V. G. C. Bioorg Med Chem Lett 2013, 23,
6805.
[18] Xu, Z.; Song, X. F.; Hu, Y. Q.; Qiang, M.; Lv, Z. S. Eur J Med
Chem 2017, 138, 66.
[19] Thomas, K. D.; Adhikari, A. V.; Chowdhury, I. H.; Sumesh,
E.; Pal, N. K. Eur J Med Chem 2011, 46, 2503.
[20] Lin, H. N.; Walsh, C. T. J Am Chem Soc 2004, 126, 13998.
[21] McPherson, J. C.; Royce, R.; Thomas, B. B.; Hartmann, J. F.;
Farcasiu, D.; Bereczki, I.; Rȍth, E.; Tollas, S.; Ostorházi, E.; Rozgonyi, F.;
Herczegh, P. Eur J Med Chem 2012, 47, 615.
[22] Kumar, K.; Pradines, B.; Madamet, M.; Amalvict, R.; Benoit,
N.; Kumar, V. Eur J Med Chem 2014, 87, 801.
52.89; H, 4.43; N, 17.61.
MIC determination. Hybrids 5a–j along with MXFX,
RIF, and INH were evaluated in vitro activity against
MTB H37Rv and MDR-TB via rapid direct susceptibility
test technique [18]. The compounds together with the
references MXFX, RIF, and INH were dissolved in
dimethyl sulfoxide (DMSO) and twofold diluted at
concentrations from 0.0125 to 200 μg/mL (for MTB
H37Rv) or 0.062 to 128 μg/mL (for MDR-MTB). The
wells of a sterile 48-well plate were filled with 100 mL
twofold diluted tested compounds and 100 mL MTB
H37Rv
or
MDR-MTB
suspension
containing
4 × 10À3 mg cells. Pure medium replaced the diluted
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet