Synthesis of isoniazid-1,2,3-triazole conjugates: Antitubercular, antimicrobial evaluation and molecular docking study

Article abstract of DOI:10.1002/jhet.4072

In the present study, a series of new isoniazid-1,2,3-triazole conjugates (5a-k) was synthesized via click chemistry approach. The newly synthesized compounds were assessed for their in vitro antitubercular and antimicrobial activities. The compound 5g ha

Full text of DOI:10.1002/jhet.4072

Synthesis of isoniazid-1,2,3-triazole conjugates: Antitubercular,
antimicrobial evaluation and molecular docking study
Adinath D. Badar1, Shubham M. Sulakhe1, Mahesh B. Muluk1, Naziya N. M. A.
Rehman2, Prashant P. Dixit2, Prafulla B. Choudhari3, Estharla Madhu Rekha4,
Dharmarajan Sriram4, Kishan P. Haval1*
1Department of Chemistry, Dr. Babasaheb Ambedkar Marathwada University SubCampus,
Osmanabad 413501, India
2Department of Microbiology, Dr. Babasaheb Ambedkar Marathwada University SubCampus,
Osmanabad 413501, India
3Department of Pharmaceutical Chemistry, Bharati Vidyapeeth College of Pharmacy, Kolhapur
416013, India
4Department of Pharmacy, Birla Institute of Technology and Science-Pilani, Hyderabad Campus,
Jawahar Nagar, Shameerpet Mandal, R. R. District, Hyderabad 500078, India
Correspondence: Dr. Kishan P. Haval, Email: havalkp@gmail.com
GRAPHICAL ABSTRACT
ABSTRACT
In the present study, a series of new isoniazid-1,2,3-triazole conjugates (5a-k) was
synthesized via click chemistry approach. The newly synthesized compounds were assessed
for their in vitro antimycobacterial and antimicrobial activities. The compound 5g has
displayed potent antitubercular activity against M. tuberculosis H37Rv (Mtb) with MIC value
1.56 μg/mL. The active compounds were screened for their cytotoxicity profile by MTT
assay against RAW 264.7 cell line. The four compounds have shown good in vitro
antimicrobial activities against both antibacterial and antifungal pathogens. A molecular
This article has been accepted for publication and undergone full peer review but has not been
through the copyediting, typesetting, pagination and proofreading process which may lead to
differences between this version and the Version of Record. Please cite this article as doi:
10.1002/jhet.4072
This article is protected by copyright. All rights reserved.

docking study was accomplished to identify the probable mode of action of synthesized
derivatives. These compounds have shown excellent binding affinity towards Enoyl-acp
reductase (INHA) and DNA gyrase.
KEYWORDS: 1,2,3-Triazole, Isoniazid, Antitubercular Activity, Antimicrobial Activity,
Cytotoxicity, Molecular Docking Study, Click Chemistry.
1. INTRODUCTION
Tuberculosis (TB) is a chronic disease that gets spread through air and caused by the bacillus
Mycobacterium tuberculosis. It is one of the leading reason of death from a single infectious
agent. It affects the lungs (pulmonary TB) and other sites (extra pulmonary TB).[1] As per
Global Tuberculosis Report-2019, tuberculosis (TB) is among the top ten reasons of death
worldwide.[2] It has more become difficult to combat the disease due to its poverty and co-
infection with HIV. The development of resistance is a serious problem associated with the
treatment of TB. The genetic mutation is one of the main reason of resistance. The current
attempts in the drug discovery process are not sufficient to completely eliminate the
tubercular epidemic.[3] It is observed that interest in tuberculosis research is rising, and the
control of its spread has become one of the main health priorities in the world.[4] As limited
treatment options for multi-drug resistant (MDR-TB) and extensively drug resistant (XDR-
TB) are available, TB researchers have the challenge of inventing new anti-tubercular drugs
with innovative modes of action.[5, 6]
A literature survey shown that 1,4-disubstituted 1,2,3-triazole derivatives have several
therapeutic properties like antifungal,[7] antibacterial,[8] anticancer,[9] anti-HIV,[10]
antidiabetic,[11] antitubercular[12] and antiviral.[13] They can exhibit hydrogen bonding, dipole-
dipole and µ-staking interactions.[14] Recently, triazole has gained exceptional consideration
in drug discovery.[15] It is an important scaffold of many drugs like tazobactum,
cephalosporin, cetirizine, fluconazole, itraconazole, voriconazole and ketoconazole.[16] In
addition, these are very stable to acidic and basic hydrolysis. It does not react with various
oxidizing and reducing agents.[17] In view of these important features, numerous protocols for
the synthesis of 1,2,3-triazole derivatives have been established.[18] The most useful method
is the Huisgen’s 1,3-dipolar Cycloaddition of azides and alkynes. Recently, Sharpless and
Meldal group have reported new protocol for 1,3-dipolar cycloaddition reaction with
dramatic rate enhancement and improved region-selectivity. “Click Chemistry” prescribed by
Sharpless has turn out to be a premier module of synthetic organic chemistry.[19]
2
This article is protected by copyright. All rights reserved.

Isonicotinic acid hydrazide (Isoniazid) is one of the first-line drug used for the treatment
of Mycobacterium tuberculosis. Its mode of action consist of several effects on lipids,
glycolysis, biomembranes, proteins and nucleic acid synthesis.[20] Unfortunately, it has
several adverse effects mainly, hepatitis, psychiatric, GI Intolerance, peripheral neuropathy,
allergic reactions and drug interactions.[21] Hence, it is prime important to synthesis novel
isoniazid derivatives.[22] To overcome the drug resistance and adverse effects, incorporation
of isoniazid with other active moiety like 1,2,3-triazole is frequently applied (Figure 1).
FIGURE 1 Representative isoniazid-1,2,3-triazole derivatives having antitubercular activity
It has been observed that the combination of lipophilic moieties with the skeleton of INH
can enhance permeation of the drug into bacterial cells, hence increasing the anti-TB activity.
Therefore, INH conjugates with better lipophilicity are evolving as one of the most potential
anti-TB compounds. Rawat and coworkers have reported the synthesis of novel amido-ether
(A) and 1,2,3-triazole (B) derivatives of isoniazid and evaluation of their in vitro and in vivo
antitubercular activity (Figure 1).[23, 24] The compound PA-824 (C) has shown outstanding
activities against the both replicating and non-replicating cultures of MTB including MDR-
TB.[25] It is in phase II clinical trial for treatment of TB infection patients. Boechat and
coworkers have reported isoniazid-N-phenyl-1,2,3-triazole derivatives and screened for in
vitro for antimycobacterial activity against MTB H37Rv.[26] All of the hybrid molecules have
shown substantial activity with MIC values ranging from 0.62 to 2.5 µg/mL. Thus, these the
two entities on molecular hybridization to form one new single molecule may offer a new
lead with potent anti-tubercular activity.[27] In extension of our efforts towards the
identification of new anti-tuberculosis agents[28] herein, we have planned and synthesized a
series of new isoniazid clubbed with 1,4-disubstituted 1,2,3-triazole conjugates. The newly
3
This article is protected by copyright. All rights reserved.

synthesized conjugates were screened for their in vitro antitubercular and antimicrobial
activities. The cytotoxicity and molecular docking study of active compounds have also been
performed.
2. MATERIALS AND METHODS
All the chemicals are obtained from commercial suppliers and used directly without further
purification. Melting points were determined in open capillary tubes and are uncorrected. The
IR spectra were obtained by using Brukar FT-IR spectrometer. 1H and 13C NMR spectra were
recorded on a Brukar DRX-400 MHz NMR spectrometer. Tetramethylsilane (TMS) was used
as an internal standard. High-resolution mass spectra (HRMS) was performed by using
XEVO G2-XS QTOF (TOF MS ES+) instrument.
2.1. Synthesis of 3,5-dichloro-2-(prop-2-yn-1-yloxy)benzaldehyde (2).
A mixture of commercially available 3, 5-dichloro salicylaldehyde (1) (1 mmol), propargyl
bromide (1 mmol) and K2CO3 (2 mmol) was stirred in DMF at room temperature. The
progress of the reaction was monitored by TLC. After completion of the reaction, the reaction
mixture was poured on crushed ice. The solid obtained was filtered, washed with water and
crystallized from ethanol.
Yield: 95%, M.P.: 81-83oC; 1H NMR (400 MHz, CDCl3)  = 2.55 (s, 1H, -CH), 4.89 (s, 2H, -
OCH2), 7.64 (d, J = 4 Hz, 1H, Ar-H), 7.76 (d, J = 4 Hz, 1H, Ar-H), 10.38 (s, 1H, -CHO); 13C
NMR (100 MHz, CDCl3)  = 62.00, 77.08, 78.68, 126.57, 129.90, 131.48, 132.96, 135.73,
154.63, 188.29.
2.2. Synthesis of (E)-N'-(3,5-dichloro-2-(prop-2-yn-1-yloxy) benzylidene)isonicotino
hydrazide (3)
3,5-Dichloro-2-(prop-2-yn-1-yloxy)benzaldehyde (2) (1 mmol) and isonicotinohydrazide (1
mmol) was stirred in diisopropylethylammonium aceate (DIPEAc) (10 ml) at room
temperature for 1h. After completion of reaction, ice cold water was added in reaction
mixture. Then, the solid compound obtained was filtered, washed with cold water and dried.
The product obtained was crystallized by using ethanol.
(E)-N'-(3,5-Dichloro-2-(prop-2-yn-1-yloxy)benzylidene)isonicotinohydrazide (3)
Yield: 90%; M.P.: 160-162 oC; IR (Neat) ν cm-1: 3320, 3024, 2930, 1640, 1598, 1530, 1489,
1
1278, 1208, 1050, 911, 830; H NMR (400 MHz, CDCl3)  = 2.55 (t, J = 4 Hz, 1H, -CH),
4
This article is protected by copyright. All rights reserved.

4.80 (d, J = 4 Hz, 2H, -OCH2), 7.42-7.47 (m, 1H, Ar-H), 7.56-7.59 (m, 1H, Ar-H), 7.72-7.75
(m, 2H, Ar-H), 8.10-8.21 (m, 1H, Ar-H), 8.83 (s, 2H, Ar-H), 9.43 (s, 1H, -CON-H).
2.3. General procedure for the synthesis of (E)-N'-(3,5-dichloro-2-((1-phenyl-1H-1,2,3-
triazol-4-yl)methoxy)benzylidene)isonicotinohydrazide derivatives (5a-k)
(E)-N'-(3,5-Dichloro-2-(prop-2-yn-1-yloxy)benzylidene)isonicotino hydrazide (3) (1 mmol),
substituted azidobenzenes (4a-k) (1 mmol), CuSO4.5H2O (20 mol%) and sodium ascorbate
(20 mol%) were stirred in DMF. After completion of reactions (6-8h), ice cold water was
added in reaction mixture. The compounds obtained were filtered, washed with water, dried
and crystallized by using ethanol.
(E)-N'-(3,5-Dichloro-2-((1-(p-tolyl)-1H-1,2,3-triazol-4-yl)methoxy)benzylidene)isonicotino
hydrazide (5a)
Yield: 80%; M.P.: 213-215 oC; IR (Neat) ν cm-1: 3222, 3020, 2941, 1675, 1607, 1570, 1540,
1455, 1301, 1270, 1178, 1052, 843, 812; 1H NMR (400 MHz, CDCl3)  = 1.76 (s, 3H, -CH3),
5.03 (s, 2H, -OCH2), 6.90 (d, J = 8 Hz, 2H, Ar-H), 6.97-7.00 (m, 3H, Ar-H), 7.35 (d, J = 8
Hz, 2H, Ar-H), 7.81-7.84 (m, 2H, Ar-H), 8.27 (s, 1H, Ar-H), 8.37 (s, 1H, Ar-H), 8.41 (d, J =
2 Hz, 1H, Ar-H), 11.67 (s, 1H, -CON-H); 13C NMR (100 MHz, CDCl3 + DMSO-d6)  =
17.52, 62.38, 112.68, 121.39, 121.92, 123.38, 125.50, 126.44, 126.60, 129.69, 131.20,
132.98, 135.78, 141.41, 141.56, 142.75, 149.85, 160.67, 161.97.
(E)-N'-(3,5-Dichloro-2-((1-(4-chlorophenyl)-1H-1,2,3-triazol-4-yl)methoxy)benzylidene)
isonicotinohydrazide (5b)
Yield: 82%; M.P.: 130-132 oC; IR (Neat) ν cm-1: 3218, 3031, 2917, 1666, 1599, 1556, 1495,
1
1310, 1261, 1144, 1050, 859, 838; H NMR (400 MHz, CDCl3)  = 5.18 (s, 2H, -OCH2),
7.47-7.51 (m, 4H, Ar-H), 7.61-7.68 (m, 2H, Ar-H), 7.72-7.83 (m, 2H, Ar-H), 8.01-8.06 (m,
2H, Ar-H), 8.67 (s, 1H, Ar-H), 7.9 (s, 1H, Ar-H), 10.76 (s, 1H, -CON-H); 13C NMR (100
MHz, CDCl3 + DMSO-d6)  = 61.32, 112.83, 114.98, 117.02, 120.85, 121.47, 123.25,
126.89, 128.13, 129.73, 131.39, 137.25, 139.70, 143.20, 144.89, 150.31, 161.96, 163.62;
HRMS (ESI)+ calcd. for C22H15Cl3N6O2 [M+H]+: 501.0356 and found 501.0390.
(E)-N'-(3,5-Dichloro-2-((1-phenyl-1H-1,2,3-triazol-4-yl)methoxy)benzylidene)isonicotino
hydrazide (5c)
Yield: 86%; M.P.: 237-239 oC; IR (Neat) ν cm-1: 3227, 3008, 2949, 1663, 1603, 1544, 1455,
1
1349, 1281, 1147, 1048, 912, 870, 819; H NMR (400 MHz, CDCl3)  = 5.17 (s, 2H, -
5
This article is protected by copyright. All rights reserved.

OCH2), 7.37-7.49 (m, 6H, Ar-H), 7.63-7.79 (m, 4H, Ar-H), 8.02 (s, 1H, Ar-H), 8.15 (s, 1H,
Ar-H), 8.64 (s, 1H, Ar-H), 11.78 (s, 1H, -CON-H); HRMS (ESI)+ calcd. for C22H16Cl2N6O2
[M+H]+: 467.0745 and found 467.0801.
(E)-N'-(2-((1-(4-Bromophenyl)-1H-1,2,3-triazol-4-yl)methoxy)-3,5-dichlorobenzylidene)
isonicotinohydrazide (5d)
Yield: 83%; M.P.: 240-242 oC; IR (Neat) ν cm-1: 3237, 3053, 2912, 1644, 1617, 1560, 1513,
1
1389, 1250, 1107, 1050, 843, 822; H NMR (400 MHz, CDCl3)  = 5.16 (s, 2H, -OCH2),
7.45 (s, 1H, Ar-H), 7.55 (d, J = 8 Hz, 2H, Ar-H), 7.63 (d, J = 8 Hz, 2H, Ar-H), 7.66 (s, 1H,
Ar-H), 7.79 (bs, 2H, Ar-H), 8.01 (d, J = 4 Hz, 1H, Ar-H), 8.07 (s, 1H, Ar-H), 8.67 (s, 1H, Ar-
H), 8.77 (s, 1H, Ar-H), 10.88 (s, 1H, -CON-H); 13C NMR (100 MHz, DMSO-d6)  = 62.18,
111.56, 116.96, 118.49, 121.10, 122.03, 123.44, 124.59, 125.47, 127.34, 131.27, 132.77,
139.54, 140.27, 144.38, 150.60, 160.58, 161.34.
(E)-N'-(3,5-Dichloro-2-((1-(3-nitrophenyl)-1H-1,2,3-triazol-4-yl)methoxy)benzylidene)
isonicotinohydrazide (5e)
Yield: 90%; M. P.: 138-140 oC; IR (Neat) ν cm-1: 3220, 3008, 2939, 1655, 1598, 1560, 1507,
1
1447, 1274, 1139, 1056, 922, 858, 807; H NMR (400 MHz, CDCl3)  = 5.23 (s, 2H, -
OCH2), 7.48 (s, 1H, Ar-H), 7.62 (d, J = 4 Hz, 1H, Ar-H), 7.76-7.80 (m, 3H, Ar-H), 8.01 (s,
1H, Ar-H), 8.20-8.25 (m, 1H, Ar-H), 8.30-8.34 (m, 2H, Ar-H), 8.60-8.68 (m, 2H, Ar-H), 8.80
(s, 1H, Ar-H), 10.64 (s, 1H, -CON-H); 13C NMR (100 MHz, CDCl3 + DMSO-d6)  = 62.18,
112.65, 118.84, 120.10, 122.75, 123.51, 124.99, 126.02, 127.91, 128.61, 129.43, 131.02,
133.48, 136.79, 141.67, 142.40, 145.53, 150.48, 160.04, 161.04.
(E)-N'-(3,5-Dichloro-2-((1-(4-methoxyphenyl)-1H-1,2,3-triazol-4-yl)methoxy)benzylidene)
isonicotinohydrazide (5f)
Yield: 87%; M.P.: 180-182 oC; IR (Neat) ν cm-1: 3229, 3021, 2945, 1673, 1604, 1576, 1542,
1448, 1311, 1263, 1172, 1050, 930, 840, 802; 1H NMR (400 MHz, CDCl3)  = 3.87 (s, 3H, -
OCH3), 5.22 (s, 2H, -OCH2), 7.04-7.11 (m, 3H, Ar-H), 7.39-7.47 (m, 3H, Ar-H), 7.67 (d, J =
8 Hz, 1H, Ar-H), 7.73-7.75 (m, 1H, Ar-H), 8.09 (s, 2H, Ar-H), 8.27 (d, J = 4 Hz, 1H, Ar-H),
8.56 (s, 1H, Ar-H), 10.73 (s, 1H, -CON-H); 13C NMR (100 MHz, CDCl3 + DMSO-d6)  =
55.89, 62.42, 112.40, 112.80, 120.93, 122.04, 123.49, 124.98, 125.42, 126.24, 127.85,
130.49, 132.69, 141.20, 141.55, 142.93, 150.87, 160.94, 162.94; HRMS (ESI)+ calcd. for
C23H18Cl2N6O3 [M+H]+: 497.0851 and found 497.0909.
6
This article is protected by copyright. All rights reserved.

(E)-N'-(3,5-Dichloro-2-((1-(2-chlorophenyl)-1H-1,2,3-triazol-4-yl)methoxy)benzylidene)
isonicotinohydrazide (5g)
Yield: 85%; M.P.: 167-169 oC; IR (Neat) ν cm-1: 3240, 3089, 2945, 1670, 1600, 1581, 1510,
1
1487, 1319, 1244, 1169, 1055, 861, 822; H NMR (400 MHz, CDCl3)  = 5.22 (s, 2H, -
OCH2), 7.42-7.49 (m, 4H, Ar-H), 7.49-7.59 (m, 2H, Ar-H), 7.78-7.87 (m, 2H, Ar-H), 7.98 (s,
1H, Ar-H), 8.05 (d, J = 4 Hz, 1H, Ar-H), 8.66 (s, 1H, Ar-H), 8.75 (s, 1H, Ar-H), 11.11 (s, 1H,
13
-CON-H); C NMR (100 MHz, CDCl3 + DMSO-d6)  = 62.41, 112.48, 120.97, 122.14,
123.52, 125.05, 126.42, 126.72, 127.78, 128.13, 130.61, 131.28, 134.29, 141.57, 141.78,
142.96, 145.88, 150.95, 160.91, 162.26; HRMS (ESI)+ calcd. for C22H15Cl3N6O2 [M+H]+:
501.0356 and found 501.0406.
(E)-N'-(3,5-Dichloro-2-((1-(2-methoxyphenyl)-1H-1,2,3-triazol-4-yl)methoxy)benzylidene)
isonicotinohydrazide (5h)
Yield: 82%; M.P.: 178-180 oC; IR (Neat) ν cm-1: 3239, 3062, 2982, 1686, 1605, 1580, 1537,
1
1377, 1248, 1171, 1044, 887, 835; H NMR (400 MHz, CDCl3)  = 3.87 (s, 3H, -OCH3),
5.22 (s, 2H, -OCH2), 7.04-7.11 (m, 4H, Ar-H), 7.39-7.47 (m, 3H, Ar-H), 7.67 (d, J = 8 Hz,
1H, Ar-H), 7.74 (d, J = 8 Hz, 1H, Ar-H), 8.10 (s, 1H, Ar-H), 8.27 (d, J = 4 Hz, 1H, Ar-H),
8.59 (s, 1H, Ar-H), 10.88 (s, 1H, -CON-H); 13C NMR (100 MHz, CDCl3 + DMSO-d6)  =
56.17, 61.17, 112.71, 117.96, 119.92, 121.20, 122.25, 123.76, 124.53, 125.27, 126.57,
127.73, 130.77, 135.31, 138.01, 140.52, 142.32, 143.13, 151.18, 161.23, 162.48.
(E)-N'-(3,5-Dichloro-2-((1-(3-chlorophenyl)-1H-1,2,3-triazol-4-yl)methoxy)benzylidene)
isonicotinohydrazide (5i)
Yield: 86%; M.P.: 125-127 oC; IR (Neat) ν cm-1: 3267, 3112, 3081, 2803, 1674, 1611, 1557,
1
1388, 1260, 1142, 1060, 934, 856, 809; H NMR (400 MHz, CDCl3)  = 5.20 (s, 2H, -
OCH2), 7.42-7.52 (m, 4H, Ar-H), 7.60-7.630 (m, 1H, Ar-H), 7.76-7.81 (m, 3H, Ar-H), 8.03-
13
8.11 (m, 2H, Ar-H), 8.69 (s, 1H, Ar-H), 8.81 (s, 1H, Ar-H), 10.55 (s, 1H, -CON-H); C
NMR (100 MHz, CDCl3 + DMSO-d6)  = 62.52, 112.78, 115.69, 118.27, 120.10, 122.50,
123.42, 125.84, 126.68, 128.61, 130.97, 134.90, 137.39, 139.03, 141.57, 142.99, 143.35,
149.54, 160.77, 162.24.
(E)-N'-(3,5-Dichloro-2-((1-(3-methoxyphenyl)-1H-1,2,3-triazol-4-yl)methoxy)benzylidene)
isonicotinohydrazide (5j)
7
This article is protected by copyright. All rights reserved.

Yield: 85%; M.P.: 190-192 oC; IR (Neat) ν cm-1: 3210, 3123, 3017, 2939, 1681, 1618, 1550,
1
1490, 1322, 1269, 1143, 1052, 847, 819; H NMR (400 MHz, CDCl3)  = 3.86 (s, 3H, -
OCH3), 5.21 (s, 2H, -OCH2), 6.98-7.01 (m, 1H, Ar-H), 7.20-7.23 (m, 2H, Ar-H), 7.29-7.33
(m, 1H, Ar-H), 7.40-7.44 (m, 1H, Ar-H), 7.47-7.50 (m, 1H, Ar-H), 7.88-7.92 (m, 1H, Ar-H),
8.05-8.09 (m, 2H, Ar-H), 8.66 (s, 1H, Ar-H), 8.79 (s, 1H, Ar-H), 10.50 (s, 1H, -CON-H); 13C
NMR (100 MHz, CDCl3 + DMSO-d6)  = 55.57, 62.56, 112.09, 112.63, 113.19, 114.31,
121.21, 121.94, 123.05, 123.42, 126.86, 130.74, 135.76, 137.54, 141.53, 142.68, 142.97,
144.43, 150.15, 160.32, 161.02; HRMS (ESI)+ calcd. for C23H18Cl2N6O3 [M+H]+: 497.0851
and found 497.0883.
(E)-N'-(3,5-Dichloro-2-((1-(o-tolyl)-1H-1,2,3-triazol-4-yl)methoxy)benzylidene)isonicotino
hydrazide (5k)
Yield: 83%; M.P.: 270-272 oC; IR (Neat) ν cm-1: 3228, 3031, 2944, 1670, 1596, 1559, 1463,
1317, 1265, 1180, 1050, 850, 824; 1H NMR (400 MHz, CDCl3)  = 2.02 (s, 3H, -CH3), 5.05
(s, 2H, -OCH2), 6.85 (d, J = 8 Hz, 1H, Ar-H), 6.95-7.02 (m, 1H, Ar-H), 7.19 (d, J = 8 Hz, 1H,
Ar-H), 7.27-7.29 (m, 4H, Ar-H), 7.41 (s, 1H, Ar-H), 7.85 (d, J = 8 Hz, 1H, Ar-H), 8.18 (d, J
= 4 Hz, 1H, Ar-H), 8.39 (s, 1H, Ar-H), 8.45 (d, J = 4 Hz, 1H, Ar-H), 11.68 (s, 1H, -CON-H);
13C NMR (100 MHz, CDCl3 + DMSO-d6)  = 17.52, 62.38, 112.68, 121.39, 121.92, 123.38,
125.00, 125.50, 126.44, 126.60, 129.69, 131.20, 132.98, 135.78, 140.05, 141.41, 141.56,
142.75, 149.85, 160.67, 161.97.
3. RESULT AND DISCUSSION
3.1. Chemistry
The target compounds (5a-k) were synthesized by following reaction sequence as shown in
Scheme 1. In the first step, the propargylation of 3,5-dichloro-2-hydroxybenzaldehyde (1)
was done by using propargyl bromide and K2CO3 in DMF at room temperature.[29] Then, the
condensation
of
3,5-dichloro-2-(prop-2-yn-1-yloxy)benzaldehyde
(2)
and
isonicotinohydrazide was performed in diisopropylethylammonium acetate (DIPEAc) to
furnish the (E)-N'-(3,5-dichloro-2-(prop-2-yn-1-yloxy)benzylidene)isonicotinohydrazide
(3).[30]
Cycloaddition
reaction
(Click)
of
(E)-N'-(3,5-dichloro-2-(prop-2-yn-1-
yloxy)benzylidene)isonicotinohydrazide (3) and various substituted azidobenzenes (4a-k) by
using CuSO4.5H2O and sodium ascorbate was performed to obtain the corresponding (E)-N'-
8
This article is protected by copyright. All rights reserved.

(3,5-dichloro-2-((1-phenyl-1H-1,2,3-triazol-4-yl)methoxy)benzylidene)isonicotinohydrazide
derivatives (5a-k) in 80-90% yields.
SCHEME 1. Reagents and conditions: (i) Propargyl bromide, K2CO3, DMF, rt, 6h (92%);
(ii) Isonicotinohydrazide, DIPEAc, rt, 1h (90%); (iii) Substituted azidobenzenes (4a-k),
CuSO4, Na ascorbate, DMF, rt (80-90%)
1
13
The structures of new compounds were assigned with the help of IR, H NMR, CNMR
and HRMS spectral data. In IR spectrum of compound 5g, the peaks at 3240 and 1670 cm-1
1
were due to N-H and C=O functional groups. The H NMR of compound 5g displayed a
singlet at  5.22 due to –O-CH2-triazolyl. The N-H proton of the amide group appeared at 
13
11.11. All aromatic protons appeared in the region of  7.42 to 8.75. The C NMR spectra
showed peak at  62.41 was assigned to methylene carbon (–O-CH2-triazolyl). The peak for
C=O group is appeared at  162.26. The structure assigned to compound 5g was further
strengthen by its HRMS spectrum. It has exhibited [M+H]+ ion peak at m/z 501.0406 for the
molecular formula C22H15Cl3N6O2.
3.2. Antitubercular activity and cytotoxicity
The antitubercular screening of isoniazid-1,2,3-triazole derivatives was performed by
procedure reported in literature.[31] The four derivatives have exhibited good antitubercular
activity. The compound 5g is equally active to standard antitubercular drug, Ciprofloxacin
with MIC value 1.56 µg/mL. It has shown better activity than the antitubercular drug,
Ethambutol. The compound 5g and 5h have displayed antitubercular activity with 2-Cl and 2-
OCH3 substituents, respectively. Similarly, compound 5b with 4-Cl substituent has shown
good anti-TB activity. Thus, the chloro and methoxy substituents have played vital role in
possessing the activity.
The in vitro cytotoxicity of the most active antitubercular derivatives with lower MIC
value were evaluated against growth inhibition of RAW 264.7 cells at 25 μg/mL
9
This article is protected by copyright. All rights reserved.

concentration by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)
assay.[32] The results obtained indicate that these compounds are not harmful to the normal
cells (Table 1).
TABLE 1 Physical data and antitubercular activity of 1,2,3-triazole derivatives (5a-k)
MIC against
Mtb H37Rv
strain
%
Yield
(%)
Inhibition
Cytotoxicity
at 25 μg/mL
Entry
Triazole derivatives
M.P. (oC)
(μg/mL)
160-162
90
80
>25
>25
NA
NA
3
213-215
5a
130-132
237-239
240-242
138-140
82
86
83
90
12.5
6.25
>25
>25
NA
24.54
NA
5b
5c
5d
5e
NA
180-182
87
>25
NA
5f
10
This article is protected by copyright. All rights reserved.

167-169
178-180
125-127
190-192
270-272
85
82
86
85
88
1.56
12.5
>25
>25
>25
22.04
NA
5g
5h
5i
NA
NA
5j
NA
5k
Isoniazid
Ciprofloxacin
Ethambutol
0.1
1.56
3.125
3.3. Antimicrobial activity
Newly synthesized isoniazid-1,2,3-triazole conjugates (5a-k) were screened for their in vitro
antimicrobial activities by agar well diffusion assay.[33] Fluconazole and Tetracycline were
used as reference standard for antifungal and antibacterial activities, respectively. The
compounds were dissolved in DMSO and the concentration was adjusted to 1 mg/mL.
Inoculums of each bacterial and fungal pathogen was developed by inoculating pathogens in
nutrient broth and keeping them for 24 h at 370C. The turbidity was adjusted to the 0.5
McFarland standards by diluting bacterial suspension using sterile saline. The diluted
suspension (200 µL) of each pathogen was inoculated on sterile Mueller Hinton agar plates.
The wells were prepared in agar and filled with 100 µL of the samples. Incubation of all
experimental Petri plates was allowed at 37oC for 24h. After incubation, the plates were
keenly observed and results were recorded.
The compounds 5d, 5h, 5i and 5k have exhibited good antimicrobial activities against
both antibacterial and antifungal pathogens (Table 2). It has been observed that the
11
This article is protected by copyright. All rights reserved.

compounds with electron donating substituents like –OCH3 and –CH3 have shown better
antimicrobial activities. We are expecting that on structural modifications in these active
compounds will gain new antimicrobial agents.
TABLE 2 Antimicrobial activity of 1,2,3-triazole derivatives (5a-k)
Entry →
5a 5b 5c 5d 5e 5f 5g 5h 5i 5j 5k Standard
Pathogens ↓
07 -- -- 17 16 14 -- 18 13 -- 18
-- 10 -- 12 14 16 -- 16 14 12 16
-- 13 08 12 15 14 12 14 16 14 18
-- -- -- 18 -- 12 -- 15 14 -- 14
09 12 -- 19 14 12 10 17 08 -- 18
-- 10 -- 16 -- -- -- 16 15 10 16
10 15 11 14 -- 14 -- 14 12 -- 13
-- -- 06 15 -- 05 07 12 08 15 14
-- 08 -- 13 -- -- -- 10 06 12 15
29
33
32
33
29
33
32
34
27
30
30
30
S. aureus
B. cerus
B. subtilis
E. aerogenes
E. coli
S. typhi
P. aeruginosa
S. boydii
S. abony
-- -- -- -- -- -- -- 06
-- 12
A. niger
10 -- -- 06 -- -- -- 16 13 -- 11
-- 07 -- -- -- -- -- 09 09 -- 11
C. albicans
S. cerevisiae
(--): Not active
The MIC values were determined for the compounds having good antimicrobial activities.
It was performed by using the method and guidelines of the Clinical and Laboratory Standard
Institute (CLSI). The results are expressed in µg/mL (Table 3).
TABLE 3 MIC values of most potent isoniazid-1, 2, 3-triazole derivatives
Pathogens 5d 5h
S. typhi 150 110 160 120
B. subtilis 180 130 90 80
5j
5k Tetracycline
20
25
18
20
E. coli
140 90 110 75
110 70 170 60
S. aureus
3.4. Molecular docking analysis for antitubercular activity
A molecular docking study was performed to find the possible mode of action of synthesized
compounds for antitubercular and antibacterial activities. Enoyl-ACP Reductase (INHA)
12
This article is protected by copyright. All rights reserved.

important enzyme involved in the fatty acid biosynthesis in mycobacterium. It is responsible
for the cell wall synthesis in mycobacteria. DNA gyrase is involved in bacterial cell growth. It
is well-known antibacterial target for many established bactericidal agents like ciprofloxacin.
Molecule structures were drawn using molecule builder module of V life MDS 4.6. They
were further optimised via application of merck molecular force field (MMFF). The crystal
structure of Enoyl-Acp Reductase (INHA) (PDB ID: 1ZID) and S. aureus DNA gyrase (PDB
ID: 6QX1) were taken from the free protein database www.rcsb.org and utilised for the
docking study.[34, 35] Grip based docking simulation was done keeping rotational angle to 10o
and number of placement to the 30. Molecular docking analysis was validated via redocking
protocol. The RMSD for the co-crystallised ligand ZID in Enoyl-Acp Reductase (INHA)
(PDB ID: 1ZID) was found to be 0.29 Ao and for co-crystallised ligand JK8 aureus DNA
gyrase (PDB ID: 6QX1) was found to be 0.76 Ao, which indicated the applied docking
protocol can efficiently predict key drug receptors interactions.
Derivative 5b was interacting with Enoyl-Acp Reductase (INHA) with total docking score
(PLP) of -53.95 kcal/mol. It was interacted via formation of hydrogen bond with LYS165,
aromatic interaction with PHE97, hydrophobic interaction with ARG43, PHE97 and Vander
wall interactions with ILE16, ILE21, PHE41, ASP42, ARG4, LEU63, SER94, ILE95,
GLY96, PHE97, MET98, MET110, MET147, MET161, LYS165, and MET199 (Figure 2).
Derivative 5c was shown total docking score (PLP) of -63.87 kcal/mol and interacted via
formation of hydrogen bond interactions with ILE95, GLY96, LYS165 aromatic interaction
with PHE41, hydrophobic interaction with ILE16 and Vander wall interactions with ILE16,
SER20, ILE21, PHE41, LEU63, ASP64, VAL65, SER94, ILE95, GLY96, MET147,
LYS165, ILE194, THR196, LEU197, and ALA198 (Figure 3).
13
This article is protected by copyright. All rights reserved.

FIGURE 2 Docking interactions of 5b with Enoyl-Acp Reductase (INHA)
FIGURE 3 Docking interactions of 5c with Enoyl-Acp Reductase (INHA)
Derivative 5g was exhibited total docking score (PLP) of -77.30 kcal/mol and interacting
via formation of hydrogen bond with GLY14, hydrophobic interactions with ILE16, SER20,
ILE21 and Vander wall interactions with GLY14, ILE15, ILE16, SER20, ILE21, ALA22,
VAL65, SER94, ILE95, GLY96, PHE97, ILE122, MET147, LYS165, ALA191, ILE194,
THR196, LEU197, and ALA198 (Figure 4). Derivative 5h was found to have total docking
score (PLP) of -82.23 kcal/mol. It was interacting via formation of hydrogen bond with
SER94, hydrophobic interactions with ILE16, GLY40, PHE41, ILE47, ILE95 and Vander
wall interactions with SER13, GLY14, ILE16, SER20, ILE21, THR39, GLY40, PHE41,
14
This article is protected by copyright. All rights reserved.

ASP64, VAL65, SER94, ILE95, GLY96, ILE122, MET147, PHE149, LYS165, and ALA198
(Figure 5).
FIGURE 4 Docking interactions of 5g with Enoyl-Acp Reductase (INHA)
FIGURE 5 Docking interactions of 5h with Enoyl-Acp Reductase (INHA)
3.5. Molecular docking analysis for antimicrobial activity
Derivative 5d was found to have total docking score (PLP) of -62.62 kcal/mol. It was
interacting with DNA gyrase via formation of hydrogen bond with ARG342, hydrophobic
interactions with ARG342, GLU634 and Vander wall interactions with MET27, ILE30,
VAL31, ARG342, PRO343, GLU634, and ALA637 (Figure 6). Derivative 5h was exhibited
15
This article is protected by copyright. All rights reserved.

total docking score (PLP) of -58.71 kcal/mol. It was interacting via formation of hydrogen
bond with LEU345 hydrophobic interactions with ARG342, GLU634 and Vander wall
interactions with MET179, ILE336, ARG342, PRO343, LYS344, LEU345, ARG630,
ILE633, GLU634, and ALA637 (Figure 7).
FIGURE 6 Docking interactions of 5d with DNA Gyrase
FIGURE 7 Docking interactions of 5h with DNA Gyrase
Derivative 5j have total docking score (PLP) of -63.00 kcal/mol. It was interacting via
formation of hydrogen bond with ARG630, hydrophobic interactions with LYS344 and
Vander wall interactions with ARG342, PRO343, LEU345, ARG630, GLU634, ALA637
(Figure 8). Derivative 5k has total docking score (PLP) of -74.23 kcal/mol. It was found to be
16
This article is protected by copyright. All rights reserved.

interacting via the formation of hydrogen bond with LEU345, hydrophobic interactions with
ARG342, GLU634 and Vander wall interactions with MET27, ARG342, PRO343, ARG630,
ILE633, GLU634, and ALA637 (Figure 9).
FIGURE 8 Docking interactions of 5j with DNA Gyrase
FIGURE 9 Docking interactions of 5k with DNA Gyrase
4. CONCLUSION
17
This article is protected by copyright. All rights reserved.

In conclusion, a series of new isoniazid-1,2,3-triazole conjugates (5a-k) was synthesized via
click reaction. These compounds were evaluated for their in vitro antimycobacterial and
antimicrobial activities. The compound 5g was identified as potent antitubercular agent
against M. tuberculosis H37Rv (Mtb) with MIC value 1.56 μg/mL. However, the three
compounds, 5b, 5c and 5h have exhibited moderate antitubercular activity in the range of
MIC value 6.25-12.5 μg/mL. These compounds have displayed low cytotoxicity profile by
MTT assay against RAW 264.7 cell line. The four compounds, 5d, 5h, 5j and 5k have shown
good in vitro antimicrobial activities against both antibacterial and antifungal pathogens. A
molecular docking study was performed and these compounds have shown excellent binding
affinity towards Enoyl-acp reductase (INHA) and DNA gyrase. We feel that these
compounds with antitubercular and antimicrobial activities will be helpful for invention of
potential lead molecules for further improvement.
CONFLICT OF INTEREST
The authors declare no conflict of interest.
ACKNOWLEDGMENTS
We are thankful to Dr. B. A. M. University, Aurangabad for financial assistance (MRP File
No. STAT/V1/RG/Dept/2019-20/323-324) and Birla Institute of Technology and Science-
Pilani, Hyderabad for performing antitubercular screening.
REFERENCES
[1] Ang, M. L. T.; Zainul Rahim, S. Z.; de Sessions, P. F.; Lin, W.; Koh, V.; Pethe, K.;
Hibberd, M. L.; Alonso, S. Front. Microbiol., 2017, 8, 710.
[2] World Health Organization (WHO), WHOGlobal Tuberculosis Report 2019, WHO,
Geneve, Switzerland, 2019. http://www.who.int/tb/publications/global_report/en/
[3] Bahuguna, A.; Rawat, D. S. Med Res Rev, 2020, 40, 693-764.
[4] Garrido-Cardenas, J. A.; de Lamo-Sevilla, C.; Cabezas-Fernández, M. T.; Manzano-
Agugliaro F.; Martínez-Lirola, M. Tuberculosis, 2020, 121, 101917.
[5] Koul, A.; Arnoult, E.; Lounis, N.; Guillemont, J.; Andries, K. Nature, 2011, 469, 483-
490.
[6] Singh, V.; Mizrahi, V. Drug Discov. Today, 2016, 22, 503-509.
[7] Ashok, M.; Holla, B. S. J. Pharmacol. Toxicol., 2007, 2, 256-263.
[8] Shaikh, M. H.; Subhedar, D. D.; Arkile, M.; Khedkar, V. M.; Jadhav, N.; Sarkar, D.;
Shingate, B. B. Bioorg. Med. Chem. Lett., 2016, 26, 561-569.
18
This article is protected by copyright. All rights reserved.

[9] Bollu, R.; Palem, J. D.; Bantu, R.; Guguloth, V.; Nagarapu, L.; Polepalli, S.; Jain, N.
Eur. J. Med. Chem., 2015, 89, 138-146.
[10] Lazrek, H. B.; Taourirte, M.; Oulih, T.; Barascut, J. L.; Imbach, J. L.; Pannecouque, C.;
Witrouw, M.; De Clercq, E. Nucleosides Nucleotides Nucleic Acids., 2001, 12, 1949-
1960.
[11] Wang, G.; Peng, Z.; Wang, J.; Li, J.; Li, X. Bioorg. Med. Chem. Lett., 2016, 26, 5719-
5723.
[12] Costa, M. S.; Boechat, N.; Rangel, E. A.; Silva, F.; C. de Souza, A. M. T.; Rodrigues,
C. R.; Castro, H. C.; Junior, I. N.; Lourenco, M. C. S.; Wardell, S. M. S. V.; Ferreira,
V. F. Bioorg. Med. Chem., 2006, 14, 8644-8853.
[13] Krajczyk, A.; Kulinska, K.; Kulinski, T.; Hurst, B. L.; Day, C. W.; Smee, D. F.;
Ostrowski, T.; Januszczyk, P.; Zeidler, J. Antivir. Chem. Chemother., 2014, 23, 161-
171.
[14] Nalawade, J.; Shinde, A.; Chavan, A.; Patil, S.; Suryavanshi, M.; Modak, M.;
Choudhari, P. B.; Bobade, V. D.; Mhaske, P. C. Eur. J. Med. Chem., 2019, 179, 649-
659.
[15] Kumar, D.; Negi, B.; Rawat, D. S. Future Med. Chem., 2015, 14, 1981-2003.
[16] Dhumal, S. T.; Deshmukh, A. R.; Kharat, K. R.; Sathe, B. R.; Chavan, S. S.; Mane, R.
A. New J. Chem., 2019, 43, 7663-7673.
[17] Kumar, N.; Tittal, R. K.; Yadav, P.; Lal, K.; Dasharath, G. V.; Kumar, A. New. J.
Chem., 2019, 43, 8052-8058.
[18] (a) Beena; Rawat, D. S. Med Res Rev, 2013, 33, 693-764. (b) Nalla, V.; Shaikh, A.;
Bapat, S.; Vyas, R.; Karthikeyan, M.; Yogeeswari, P.; Sriram, D.; Muthukrishnan, M.
R. Soc. Open sci., 2018, 5, 171750. (c) Sajja, Y.; Vanguru, S.; Vulupala, H. R.; Bantu,
R.; Yogeswari, P.; Sriram, D.; Nagarapu, L. Bioorg. Med. Chem. Lett., 2017, 27, 5119-
5121.
[19] (a) Shaikh, M. H.; Subhedar, D. D.; Nawale, L.; Sarkar, D.; Khan, F. A. K.; Sangshetti,
J. A.; Shingate, B. B. Med. Chem. Commun., 2015, 6, 1104-1116. (b) Shaikh, M. H.;
Subhedar, D. D.; Khan, F. A. K.; Sangshetti, J. N.; Nawale, L.; Arkile, M.; Sarkar, D.;
Shingate, B. B. J. Heterocyclic Chem., 2017, 54, 413-421.
[20] Eldehna, W. M.; Fares, M.; Abdel-Aziz, M. M.; Abdel-Aziz, H. A. Molecules, 2015,
20, 8800-8815.
[21] Denholm, J. T.; McBryde, E. S.; Eisen, D. P.; Penington, J. S.; Chen, C.; Street, A. C.
Drug Healthc Patient Saf., 2014, 6, 145-149.
19
This article is protected by copyright. All rights reserved.

[22] (a) 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. (b) 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, 255-267.
[23] Kumar, D.; Khare, G.; Beena; Kidwai, S.; Tyagi, A. K.; Singh, R.; Rawat, D. S. Med.
Chem. Commun., 2015, 6, 131-137.
[24] Kumar, D.; Beena; Khare, G.; Kidwai, S.; Tyagi, A. K.; Singh, R.; Rawat, D. S. Eur. J.
Med. Chem., 2014, 81, 301-313.
[25] Sutherland, H. S.; Blaser, A.; Kmentova, I.; Franzblau, S. G.; Wan, B.; Wang, Y.; Ma,
Z.; Palmer, B. D.; Denny, W. A.; Thompson, A. M. J. Med. Chem., 2010, 53, 855-866.
[26] Boechat, N., Ferreira, V. F., Ferreira, S. B., de Lourdes, G., Ferreira, M., de C da Silva,
F., Bastos, M. M., Dos, S. C. M., Lourenço, M. C., Pinto, A. C., Krettli, A. U., Aguiar,
A. C., Teixeira, B. M., da Silva, N. V., Martins, P. R., Bezerra, F. A., Camilo, A. L., da
Silva, G. P., Costa, C. C. J. Med. Chem., 2011, 54, 5988-5999.
[27] (a) Xia, X.; Zhang, Q.; Zhao, L.; Hu, Y. Eur. J. Med. Chem., 2017, 138, 66-71. (b)
Smit, F. J.; Seldon, R.; Aucamp, J.; Jordaan, A.; Warner, D. F.; N’Da, D. D. Med.
Chem. Res., 2019, 28, 2279-2293. (c) Rizvi, F.; Khan, M.; Jabeen, A.; Siddiqui, H.;
Choudhary, M. I. Sci. Rep., 2019, 9, 6738. (d) Khare, S. P.; Deshmukh, T. R.;
Sangshetti, J. N.; Krishna, V. S.; Sriram, D.; Khedkar, V. M.; Shingate, B. B.
ChemistrySelect, 2018, 3, 13113-13122. (e) Makarov, V.; Lechartier, B.; Zhang,
M.; Neres, J.; van der Sar, A. M.; Raadsen, S. A.; Hartkoorn, R. C.; Ryabova, O.
B.; Vocat, A.; Decosterd, L. A.; Widmer, N.; Buclin, T.; Bitter, W.; Andries, K.; Pojer,
F.; Dyson, P. J.; Cole, S. T. EMBO Mol Med., 2014, 6, 372-83. (f) Oliveira, P. F. M.;
Guidetti, B.; Chamayou, A.; André-Barrès, C.; Madacki, J.; Korduláková, J.; Mori, G.;
Orena, B. S.; Chiarelli, L. R.; Pasca, M. R.; Lherbet, C.; Carayon, C.; Massou, S.;
Baron, M.; Baltas, M. Molecules, 2017, 22, 1457. (g) Shanmugavelan, P.; Nagarajan,
S.; Sathishkumar, M.; Ponnuswamy, A.; Yogeeswari, P.; Sriram, D. Bioorg. Med.
Chem. Lett., 2011, 21, 7273-7276.
[28] Phatak, P. S.; Bakale, R. D.; Dhumal, S. T.; Dahiwade, L. K.; Choudhari, P. B.;
Krishna, V. S.; Sriram, D.; Haval, K. P. Synth. Commun., 2019, 49, 2017-2028.
[29] Phatak, P. S.; Sathe, B. P.; Dhumal, S. T.; Rehman, N. N. M. A.; Dixit, P. P.; Khedkar,
V. M.; Haval, K. P. J. Heterocycl. Chem. 2019, 56, 1928-1938.
[30] Muluk, M. B.; Phatak, P. S.; Pawar, S. B.; Dhumal, S. T.; Rehman, N. N. M. A.; Dixit,
P. P.; Choudhari, P. B.; Haval, K. P. J. Chin. Chem. Soc. 2019, 66, 1507-1517.
20
This article is protected by copyright. All rights reserved.

[31] (a) Collins, L. A.; Franzblau, S. G. Antimicrob. Agents Chemother. 1997, 41, 1004-
1009. (b) Krishna, V. S.; Zheng, S.; Rekha, E. M.; Guddat, L. W.; Sriram, D. J Comput
Aided Mol Des, 2019, 33, 357-366.
[32] Van Meerloo, J., Kaspers, G. J., Cloos, J. Methods Mol Biol., 2011, 731, 237-245.
[33] Muluk, M. B.; Dhumal, S. T.; Rehman, N. N. M. A.; Dixit, P. P.; Kharat, K. R.; Haval,
K. P. ChemistrySelect, 2019, 4, 8993-8997.
[34] (a) Muluk, M. B.; Dhumal, S. T.; Phatak, P. S.; Rehman N. N. M. A.; Dixit, P. P.;
Choudhari, P. B.; Mane, R. A.; Haval, K. P. J. Heterocycl. Chem. 2019, 56, 2411-2418.
(b) Thalji, R. K.; Raha, K.; Andreotti, D.; Checchia, A.; Cui, H.; Meneghelli, G.;
Profeta, R.; Tonelli, F.; Tommasi, S.; Bakshi, T.; Donovan, B. T.; Howells, A.; Jain, S.;
Nixon, C.; Quinque, G.; McCloskey, L.; Bax, B. D.; Neu, M.; Chan, P. F.; Stavenger,
R. A. Bioorg. Med. Chem. Lett. 2019, 29, 1407-1412.
[35] Rozwarski, D. A.; Grant, G. A.; Barton, D. H.; Jacobs Jr., W. R.; Sacchettini, J. C.
Science 1998, 279, 98-102.
SUPPLEMENTARY MATERIAL
Additional supporting information may be found online in the Supporting Information
Section at the end of this article.
21
This article is protected by copyright. All rights reserved.