Skip to main content
Future Journal of Pharmaceutical Sciences
Download PDF

Synthesis and biological evaluation of some 4-aminoquinoline derivatives as potential antitubercular agents

Future Journal of Pharmaceutical Sciences volume 6, Article number: 2 (2020) Cite this article

A Correction to this article was published on 04 February 2020

This article has been updated

Abstract

Background

Based on bioisosteric similarities with thiacetazone, a series of 7-chloro-4-aminoquinoline derivatives have been designed and synthesized. The target compounds were elucidated by NMR, mass, and FTIR spectral data. All synthesized compounds were evaluated for their in vitro antitubercular activity against Mycobacterium tuberculosis H37Rv (MTB), and human dermal fibroblast cell lines were used to assess toxicity of selected ligands.

Results

All of the designed compounds showed inhibition of MTB with MIC of 1.56–50 μM. Among the tested compounds, 7c and 7g proved to be most potent MTB inhibitors (MIC = 1.56 μM).

Conclusions

The outcome of present study suggests that most of the synthesized compounds are sensitive to Mycobacterium tuberculosis and showed acceptable range for molecular parameters. Thus, 7-chloro-4-aminoquinolines could be a useful lead for the development of new MTB inhibitory agents.

Background

Tuberculosis (TB) is considered to be the most widespread and lethal communicable disease in the world. TB is caused by an infection with the slow-growing Mycobacterium tuberculosis (MTB). According to the World Health Organization, there were an estimated 10.0 million new TB cases in 2017 with 1.3 million TB deaths. In addition, more than 65% of the world’s TB cases occur in Southeast Asia, the West Pacific, and Africa [1]. Commonly used TB treatment regimen DOTS (directly observed therapy short-course) requires taking INH, PZA, and RIF for 60 days followed by an additional 120 days of treatment with INH and RIF [2, 3]. Due to the resistance acquired by the Mycobacterium tuberculosis against various first-line drugs [4], there is a need to find new and better drug candidates for the treatment. Quinoline and analogs have always attracted the attention of industrial and academic personnel. It is being reported as having many interesting biological properties such as antimalarial [5, 6], cytotoxic [7, 8], anti-inflammatory [9, 10], antiviral [11, 12], antimicrobial [13, 14], antifungal [15], anti-Alzheimer [16], antiprotozoal [17], and antitubercular [18] activities. Quinoline is a basic pharmacophore used for the design of antitubercular agents, like mefloquine, ciprofloxacin, moxifloxacin, and bedaquiline which are already in the market [18]. Furthermore, thiosemicarbazone and semicarbazone derivatives are frequently used scaffolds in biology-orientated synthesis which possess a huge variety of pharmacological activities including an antibacterial, antifungal, antitubercular, and anticancer activity [19, 20].

In view of the above observations, the diverse pharmacological activities of these pharmacophores prompted us to synthesize the target compounds, presuming that their hybrid in a one-structural entity could potentially yield new heterocyclic compounds with significant synergistic antitubercular properties. Hence, with an aim to develop promising antitubercular agents, a series of novel 7-chloro-N-phenylquinolin-4-amine derivatives containing thiosemicarbazone and semicarbazone [19, 20], scaffolds were designed and synthesized (Fig. 1). In the present study, all target ligands are screened for their in vitro antitubercular activity against Mycobacterium tuberculosis H37Rv (MTB), and human dermal fibroblast cell line were used for toxicity study.

Fig. 1
figure 1

Design strategy for the quinoline analogs containing thiosemicarbazone/semicarbazone scaffolds

Full size image

Method

Synthesis of thiosemicarbazide and semicarbazide derivatives

An equimolar amount of thiosemicarbazide or semicarbazide hydrochloride (20 mmol) and substituted α,β-unsaturated ketones (4a-i, and 5a-i) (20 mmol) [21] were dissolved in isopropyl alcohol, and glacial acetic acid (0.1 ml) was used as a catalyst. The mixture was stirred at 85 °C for 36 h. On completion of the reaction, as monitored by TLC, the reaction mixture was cooled. Precipitate was filtered by suction and washed with cooled isopropyl alcohol and solvent ether. The structures of target compounds were established by using different spectroscopic techniques.

Antitubercular activity assay

Microplate alamar blue assay (MABA) method [22, 23] was adopted to evaluate antitubercular activities (Additional file 1).

Cytotoxic assay

MTT (3-(4, 5-dimethylthiazo-2-yl)-2,5-diphenyl-tetrazolium bromide) [24] assay protocol was used to assess the toxicity studies of selected analogs.

Results

Synthesis and spectral data

((E)-1-(4-((7-chloroquinolin-4-yl)amino)phenyl)-3-(p-tolyl)allylidene)hydrazinecarbothioamide(6a)

Yield: 55%; m.p.: 196–198 °C; IR (KBr cm−1): 3362 (NH2), 1593 (C=C), 1351 (C=S), 1170 (OCH3); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 2.62 (s, 3H, CH3), 7.05 (s, 1H, ArH), 7.37 (d, 2H, J = 8.4 Hz, ArH), 7.56 (m, 4H, ArH), 7.72–7.69 (m, 3H, ArH, -C=HC-), 7.83 (d, 1H, J = 15.6 Hz, -C=HC-), 7.85 (s, 1H, NH2), 7.88 (s, 1H, NH2), 7.91 (s, 1H, ArH), 8.18 (s, 1H, ArH), 8.42 (s, 1H, ArH), 8.55 (s, 1H, ArH), 9.95 (s, 1H, NH), 10.83 (s, 1H, =N-NH-C); LC-MS M/Z: 473 [M + H]+.

2-((E)-1-(4-((7-chloroquinolin-4-yl)amino)phenyl)-3-(4-methoxyphenyl)allylidene)hydrazinecarbothioamide(6b)

Yield: 53%; m.p.: 190–192 °C; IR (KBr cm−1): 3367 (NH2), 1593 (C=C), 1350 (C=S), 1172 (OCH3); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) 3.82 (s, 3H, OCH3), 7.02 (s, 1H, ArH), 7.34 (d, 2H, J = 8.4 Hz, ArH), 7.53 (m, 4H, ArH), 7.70–7.63 (m, 3H, ArH, -C=HC-), 7.85 (d, 1H, J = 15.6 Hz, -C=HC-), 7.87 (s, 1H, NH2), 7.89 (s, 1H, NH2), 7.88 (s, 1H, ArH), 8.18 (s, 1H, ArH), 8.40 (s, 1H, ArH), 8.58 (s, 1H, ArH), 9.93 (s, 1H, NH), 10.81 (s, 1H, =N-NH-C); LC-MS M/Z: 489 [M + H]+.

2-((E)-1-(4-((7-chloroquinolin-4-yl)amino)phenyl)-3-(3,4-dimethoxyphenyl)allylidene)hydrazinecarbothioamide(6c)

Yield: 56%; m.p.: 148–150 °C; IR (KBr cm−1): 3367 (NH2), 1265 (OCH3), 1350 (C=S); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 3.81 (s, 3H, OCH3), 3.86 (s, 3H, −OCH3), 7.02 (s, 1H, ArH), 7.45 (s, 1H, ArH), 7.38 (s, 1H, ArH), 7.53 (m, 3H, ArH), 7.72–7.69 (m, 3H, ArH, -C=HC-), 7.85 (d, 1H, J = 15.6 Hz, -C=HC-), 7.91 (s, 1H, NH2), 7.96 (s, 1H, NH2), 7.98 (s, 1H, ArH), 8.23 (s, 1H, ArH), 8.47 (s, 1H, ArH), 8.61 (s,1H, ArH), 9.91 (s, 1H, NH), 10.82 (s, 1H, =N-NH-C); LC-MS M/Z: 519 [M + H]+.

2-((E)-1-(4-((7-chloroquinolin-4-yl)amino)phenyl)-3-(3,4,5-trimethoxyphenyl)allylidene)hydrazinecarbothioamide(6d)

Yield: 66%; m.p.: 138–140 °C; IR (KBr cm−1): 3343 (NH2), 1593 (C=C), 1352 (C=S), 1128 (OCH3), 1128 (OCH3); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 3.76 (s, 3H, OCH3), 3.86 (s, 6H, -OCH3), 6.42 (s, 1H, ArH), 7.27 (d, 2H, J = 8.4 Hz ArH), 7.42 (s, 1H, ArH), 7.52 (s, 1H, ArH), 7.71–7.64 (m, 3H, ArH, -C=HC-), 7.89 (d, 1H, J = 15.6 Hz, -C=HC-), 7.92 (s, 1H, NH2), 7.95 (s, 1H, NH2), 7.98(s, 1H, ArH), 8.23 (s, 1H, ArH), 8.40 (s, 1H, ArH), 8.59 (s, 1H, ArH), 9.68 (s, 1H, NH), 10.72 (s, 1H, =N-NH-C); LC-MS M/Z: 549 [M + H]+.

2-((E)-3-(4-chlorophenyl)-1-(4-((7-chloroquinolin-4-yl)amino)phenyl)allylidene)hydrazinecarbothioamide(6e)

Yield: 73%; m.p.: 142–144 °C; IR (KBr cm−1): 3365 (NH2), 1554 (C=C), 1350 (C=S); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 7.08 (s, 1H, ArH), 7.51–7.749 (m, 3H, ArH, -C=HC-), 7.62 (d, 2H, J = 8.8 Hz, ArH), 7.70 (d,1H, J = 15.6 Hz -C=HC-), 7.78 (s, 1H, ArH), 7.89 (s, 1H, NH2), 7.91 (s, 1H, NH2), 7.95 (s, 1H, ArH), 8.01 (d, 2H, J = 8.4 Hz, ArH), 8.20 (d, 2H, J = 8.8 Hz, ArH), 8.41 (s, 1H, ArH), 8.62 (s, 1H, ArH), 10.08 (s, 1H, NH), 11.06 (s, 1H, =N-NH-C); LC-MS M/Z: 494 [M + H]+.

2-((E)-1-(4-((7-chloroquinolin-4-yl)amino)phenyl)-3-(4-fluorophenyl)allylidene)hydrazinecarbothioamide(6f)

Yield: 58%; m.p.: 178–180 °C; IR (KBr cm−1): 3354 (NH2), 1575 (C=C), 1351 (C=S); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 7.01 (s, 1H, ArH), 7.32–7.24 (m, 3H, ArH, -C=HC-), 7.52 (d, 2H, J = 8.8 Hz, ArH), 7.64 (d,1H, J = 15.6 Hz -C=HC-), 7.66 (s, 1H, NH2), 7.75 (s, 1H, NH2), 7.98 (s, 1H, ArH), 7.98–7.95 (m, 3H, ArH), 8.23–8.20 (m, 2H, ArH), 8.46 (s, 1H, ArH), 8.60 (s, 1H, ArH), 10.02 (s, 1H, NH), 11.03 (s, 1H, =N-NH-C); LC-MS M/Z: 477 [M + H]+.

2-((E)-3-(4-bromophenyl)-1-(4-((7-chloroquinolin-4-yl)amino)phenyl)allylidene)hydrazinecarbothioamide(6 g)

Yield: 66%; m.p.: 186–188 °C; IR (KBr cm−1): 3375 (NH2), 1580 (C=C), 1352 (C=S); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 6.53 (s, 1H, ArH), 6.86 (d, 1H, J = 15.6 Hz, -C=HC-), 6.99 (d, 1H, J = 12.6 Hz, -C=HC-), 7.07 (s, 1H, ArH), 7.30 (s, 1H, ArH), 7.47 (s, 1H, ArH), 7.62 (s, 1H, NH2), 7.77–7.70 (m, 4H, ArH,), 7.81 (s, 1H, NH2) 7.85 (d, 2H, J = 8.4 Hz, ArH), 8.20 (s, 1H, ArH), 8.30 (s, 1H, ArH), 8.51 (s, 1H, ArH), 10.10 (s, 1H, NH), 11.07 (s, 1H, =N-NH-C); LC-MS M/Z: 538 [M + H]+.

2-((E)-1-(4-((7-chloroquinolin-4-yl)amino)phenyl)-3-(4-nitrophenyl)allylidene)hydrazinecarbothioamide(6 h)

Yield: 47%; m.p.: 216–218 °C; IR (KBr cm−1): 3361 (NH2), 1540 (C=C), 1350 (C=S); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 7.20 (d, 1H, J = 5.6 Hz, ArH), 7.23–7.10 (m, 4H, ArH, NH2), 7.47 (d, 2H, J = 8.8 Hz, ArH), 7.71–7.60 (m, 3H, ArH, -C=HC-), 7.96 (s, 1H, NH2), 8.13 (s, 1H, ArH), 8.26 (s, 1H, ArH), 8.44–8.38 (m, 4H, ArH), 9.87 (s, 1H, NH), 11.69 (s, 1H, =N-NH-C); LC-MS M/Z: 504 [M + H]+.

2-((E)-1-(4-((7-chloroquinolin-4-yl)amino)phenyl)-3-(4-hydroxyphenyl)allylidene)hydrazinecarbothioamide(6i)

Yield: 50%; m.p.: 230–232 °C; IR (KBr cm−1): 3365 (NH2), 1567 (C=C), 1353 (C=S); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 7.20 (s, 1H, ArH), 7.27 (d, 2H, J = 8.8 Hz, ArH), 7.45–7.40 (m, 3H, ArH, CH=C), 7.73–7.61 (m, 3H, ArH, -C=HC-), 7.93 (s, 1H, NH2), 7.96 (s, 1H, NH2), 8.13 (s, 1H, ArH), 8.25 (d, 1H, ArH), 8.44–8.38 (m, 4H, ArH), 9.86 (s, 1H, NH), 9.88 (s, 1H, OH), 11.55 (s, 1H, =N-NH-C); LC-MS M/Z: 475 [M + H]+.

2-((E)-1-(4-((7-chloroquinolin-4-yl)amino)phenyl)-3-(p-tolyl)allylidene)hydrazinecarboxamide(7a)

Yield: 72%; m.p.: 148–150 °C; IR (KBr cm−1): 3425 (NH2), 1693 (C=O); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) 2.88 (s, 3H, CH3), 6.51 (s, 2H, NH2), 6.83–6.81 (d, 2H, J = 8.8 Hz, ArH), 6.86 (s, 1H, ArH), 6.90 (s, 1H, ArH), 7.60 (d, 2H, J = 8.8, ArH), 7.73 (d, 1H,, J = 15.6 Hz, -C=HC-), 7.83 (d, 1H, J = 15.6 Hz, -C=HC-), 7.85 (s, 1H, ArH), 7.93 (d, 2H, J = 8.4 Hz, ArH), 8.06 (d, 2H, J = 8.4 Hz, ArH), 8.57 (s, 1H, ArH), 8.69 (s, 1H, ArH), 9.41 (s, 1H, NH), 10.91(s, 1H, =N-NH-C); LC-MS M/Z: 457 [M + H]+.

2-((E)-1-(4-((7-chloroquinolin-4-yl)amino)phenyl)-3-(4-methoxyphenyl)allylidene)hydrazinecarboxamide(7b)

Yield: 65%; m.p.: 238–240 °C; FTIR (KBr) cm−1: 3450 (NH2), 1685 (C=O), 1251 (OCH3); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 3.72 (s, 3H, OCH3), 6.48 (s, 2H, NH2), 6.88 (d, 2H, J = 8.8 Hz, ArH), 6.96 (s, 1H, ArH), 7.13 (d, 2H, J = 8.8, ArH), 7.51 (d, 2H, J = 8.4 Hz, ArH), 7.75 (d, 1H, J = 15.6 Hz, -C=HC-), 7.78 (d, 1H, J = 15.6 Hz, -C=HC-), 7.85 (s, 1H, ArH), 7.93 (d, 2H, J = 8.8 Hz, ArH), 8.0 (s, 1H, ArH), 8.54 (s, 1H, ArH), 8.72 (s, 1H, ArH), 9.38 (s, 1H, NH), 10.76 (s, 1H, =N-NH-C); LC-MS M/Z: 473 [M + H]+.

2-((E)-1-(4-((7-chloroquinolin-4-yl)amino)phenyl)-3-(3,4-dimethoxyphenyl)allylidene)hydrazinecarboxamide(7c)

Yield: 56%; m.p.: 214–216 °C; IR (KBr cm−1): 3442 (NH2), 1681 (C=O), 1255 (OCH3); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 3.72 (s, 3H, OCH3), 3.81 (s, 3H, -OCH3), 6.50 (s, 2H, NH2), 6.81 (s, 1H, ArH), 7.20–6.96 (m, 3H, J = 8.4, ArH), 7.53 (d, 2H, J = 8.8 Hz, ArH), 7.79 (d, 1H, J = 15.6 Hz, -C=HC-), 7.81 (d, 1H, J = 15.6 Hz, -C=HC-), 7.85 (s, 1H, ArH), 7.95 (d, 2H, J = 8.4 Hz, ArH), 8.07 (s, 1H, ArH), 8.56 (s, 1H, ArH), 8.72 (s, 1H, ArH), 10.20 (s, 1H, NH), 10.81 (s, 1H, =N-NH-C); LC-MS M/Z: 503 [M + H]+.

2-((E)-1-(4-((7-chloroquinolin-4-yl)amino)phenyl)-3-(3,4,5-trimethoxyphenyl)allylidene)hydrazinecarboxamide(7d)

Yield: 52%; m.p.: 238–240 °C; IR (KBr cm−1): 3442 (NH2), 1671 (C=O), 1251 (OCH3); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 3.82 (s, 6H, OCH3), 3.87 (s, 3H, OCH3), 6.49 (s, 2H, NH2), 6.76 (s, 1H, ArH), 6.88 (s, 1H, ArH), 7.54 (d, 2H, J = 8.8 Hz, ArH), 7.71 (s, 1H, ArH), 7.81 (d, 1H, J = 15.6 Hz, -C=HC-), 7.83 (d, 1H, J = 15.6 Hz, -C=HC-), 7.93 (d, 2H, J = 8.8, ArH), 8.02 (s, 2H, ArH), 8.54 (s, 1H, ArH), 8.76 (s, 1H, ArH), 10.09 (s, 1H, NH), 11.02 (s, 1H, =N-NH-C); LC-MS M/Z: 533 [M + H]+.

2-((E)-3-(4-chlorophenyl)-1-(4-((7-chloroquinolin-4-yl)amino)phenyl)allylidene)hydrazinecarboxamide(7e)

Yield: 45%; m.p.: 174–176 °C; IR (KBr cm−1): 3335 (NH2,), 1680 (C=O), 1226 (C-N); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 6.48 (s, 2H, NH2), 7.22 (s, 1H, Ar-H), 7.54 (d, 2H, J = 8.4, Ar-H), 7.62 (d, 2H, J = 8.4 Hz, Ar-H), 7.76 (s, 1H, Ar-H), 7.87 (d, 1H, J = 15.6 Hz, −CH=C), 7.89 (d, 1H, J = 15.6 Hz, −CH=C), 7.95 (d, 2H, J = 8.8, Ar-H), 7.99 (s, 1H, Ar-H), 8.05 (s, 1H, Ar-H), 8.29 (d, 2H, J = 8.8 Hz, Ar-H), 8.62 (s, 1H, Ar-H), 10.17 (s, 1H, NH), 10.76 (s, 1H, =N-NH-C); LC-MS M/Z: 477 [M + H]+.

2-((E)-1-(4-((7-chloroquinolin-4-yl)amino)phenyl)-3-(4-fluorophenyl)allylidene)hydrazinecarboxamide(7f)

Yield: 70%; m.p.: 230–232 °C; IR (KBr cm−1): 3433 (NH2), 1686 (C=O), 1370 (C-N); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 6.54 (s, 2H, NH2), 7.22 (s, 1H, ArH), 7.44 (d, 2H, J = 8.4, ArH), 7.52 (d, 2H, J = 8.8 Hz, ArH), 7.73 (d, 1H, J = 15.6 Hz, -C=HC-), 7.76 (s, 1H, A-H), 7.83 (d, 1H, J = 15.6 Hz, -C=HC-), 7.91 (d, 2H, J = 8.8, ArH), 7.7 (s, 1H, ArH), 7.80–7.85 (m, 3H, ArH), 8.01 (s, 1H, ArH), 10.11 (s, 1H, −NH), 10.41 (s, 1H, =N-NH-C); LC-MS M/Z: 461 [M + H]+.

2-((E)-3-(4-bromophenyl)-1-(4-((7-chloroquinolin-4-yl)amino)phenyl)allylidene)hydrazinecarboxamide(7 g)

Yield: 51%; m.p.: 244–246 °C; IR (KBr cm−1): 3452 (NH2,), 1680 (C=O), 1251 (C-N); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 6.52 (s, 2H, NH2), 7.16 (s, 1H, ArH), 7.61(d, 2H, J = 8.4, ArH), 7.68 (d, 2H, J = 8.4 Hz, ArH), 7.74 (d, 1H, J = 15.6 Hz, -C=HC-), 7.78 (s, 1H, ArH), 7.81 (d, 1H, J = 15.6 Hz, -C=HC-), 7.90 (d, 2H, J = 8.0, ArH), 8.00 (s, 1H, ArH), 8.06 (s, 1H, ArH), 8.27 (d, 2H, J = 8.8 Hz, ArH), 8.62 (s, 1H, ArH), 10.18 (s, 1H, NH), 10.83 (s, 1H, =N-NH-C); LC-MS M/Z: 522 [M + H]+.

2-((E)-1-(4-((7-chloroquinolin-4-yl)amino)phenyl)-3-(4-nitrophenyl)allylidene)hydrazinecarboxamide(7 h)

Yield: 70%; m.p.: 196–198 °C; IR (KBr cm−1): 3398 (NH2), 1675 (C=O), 1585 (NO2), 1371 (C- N); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 6.50 (s, 2H, NH2), 7.20 (s, 1H, ArH), 7.42 (d, 2H, J = 8.8 Hz, ArH), 7.62 (d, 2H, J = 8.8 Hz, ArH), 7.80 (d, 1H, J = 15.6 Hz, -C=HC-), 7.83 (d, 1H, J = 15.6 Hz, -C=HC-), 7.9 (s, 1H, ArH), 8.02 (d, 2H, J = 8.4, ArH), 8.16 (s, 1H, ArH), 8.29 (d, 2H, J = 8.4 Hz, ArH), 8.53 (s, 1H, ArH), 8.62 (s, 1H, ArH), 10.30 (s, 1H, NH), 10.76 (s, 1H, =N-NH-C); LC-MS M/Z: 488 [M + H]+.

2-((E)-1-(4-((7-chloroquinolin-4-yl)amino)phenyl)-3-(4-hydroxyphenyl)allylidene)hydrazinecarboxamide(7i)

Yield: 45%; m.p.: 240–242 °C; IR (KBr cm−1): 3360 (NH2), 1680 (C=O), 1251 (C-N); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 6.53 (s, 2H, NH2), 7.23 (s, 1H, ArH), 7.56 (d, 2H, J = 8.8 Hz, ArH), 7.68 (d, 2H, J = 8.8 Hz, ArH), 7.78 (d, 1H, J = 15.6 Hz, -C=HC-), 7.81 (d, 1H, J = 15.6 Hz, -C=HC-), 7.7 (s, 1H, ArH), 8.0 (d, 2H, J = 8.2, ArH), 8.16 (s, 1H, ArH), 8.26 (d, 2H, J = 8.4 Hz, ArH), 8.51 (s, 1H, ArH), 8.60 (s, 1H, ArH), 9.89 (s, 1H, OH), 10.32 (s, 1H, NH), 10.71 (s, 1H, =N-NH-C); LC-MS M/Z: 459 [M + H]+.

2-((E)-1-(3-((7-chloroquinolin-4-yl)amino)phenyl)-3-(p-tolyl)allylidene)hydrazinecarbothioamide(8a)

Yield: 50%; m.p.: 238–240 °C; IR (KBr cm−1): 3350 (NH2), 1575 (C=C), 1352 (C=S), 1261 (C-N); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 2.62 (s, 3H, CH3), 6.99 (s, 1H, ArH), 7.20–7.15 (m, 4H, ArH), 7.25 (d, 1H, J = 15.6 Hz, -C=HC-), 7.37 (d, 2H, J = 8.4 Hz, ArH), 7.50 (d, 1H, J = 15.6 Hz, -C=HC-), 7.59 (d, 2H, J = 8.4 Hz, ArH), 7.76 (s, 1H, ArH), 7.85 (s, 1H, NH2), 7.88 (s, 1H, NH2), 7.92 (s, 1H, ArH), 8.26 (s, 1H, ArH), 8.46 (s, 1H, ArH), 9.25 (s, 1H, NH), 11.25 (s, 1H, =N-NH-C); LC-MS M/Z: 473 [M + H]+.

2-((E)-1-(3-((7-chloroquinolin-4-yl)amino)phenyl)-3-(4-Methoxyphenyl)allylidene)hydrazinecarbothioamide(8b)

Yield: 43%; m.p.: 210–212 °C; IR (KBr cm−1): 3365 (NH2), 1568 (C=C), 1350 (C=S), 1255 (OCH3); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 3.81 (s, 3H, OCH3), 7.42–7.35 (m, 4H, ArH), 7.67–7.58 (m, 3H, ArH, −NH2), 7.71 (s, 1H, NH2), 7.72 (s, 1H, ArH), 7.73 (d, 1H, J = 15.6 Hz, -C=HC-), 7.76 (d, 1H, J = 15.6 Hz, -C=HC-), 7.84 (d, 2H, J = 8.8 Hz, ArH), 7.93 (s, 1H, ArH), 8.04 (s, 1H, ArH), 8.43 (s, 1H, ArH), 8.50 (s, 1H, ArH), 9.26 (s, 1H, NH), 11.75 (s, 1H, =N-NH-C); LC-MS M/Z: 489 [M + H]+.

2-((E)-1-(3-((7-chloroquinolin-4-yl)amino)phenyl)-3-(3,4-dimethoxyphenyl)allylidene)hydrazinecarbothioamide(8c)

Yield: 41%; m.p.: 120–122 °C; IR (KBr cm−1): 3655 (NH2), 1516 (C=C), 1313 (C=S), 1267 (C-N), 1560 (C=C), 1183 (OCH3); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 3.81 (s, 3H, OCH3), 3.84 (s, 3H, −OCH3), 7.39 (s, 1H, ArH), 7.41 (s, 1H, ArH), 7.65 (s, 1H, −NH2), 7.70–7.66 (m, 3H, ArH), 7.73 (d, 1H, J = 15.6 Hz, -C=HC-), 7.80 (d, 1H, J = 15.6 Hz, -C=HC-), 7.92–7.85 (m, 3H, ArH), 7.94 (s, 1H, ArH), 8.01 (s, 1H, ArH), 8.1 (s, 1H, −NH2), 8.14 (s, 1H, ArH), 8.49 (s, 1H, ArH), 9.71 (s, 1H, NH), 11.95 (s, 1H, =N-NH-C); LC-MS M/Z: 519 [M + H]+.

2-((E)-1-(3-((7-chloroquinolin-4-yl)amino)phenyl)-3-(3,4,5-trimethoxyphenyl)allylidene)hydrazinecarbothioamide(8d)

Yield: 60%; m.p.: 240–242 °C; IR (KBr cm−1): 3352 (NH2), 1560 (C=C), 1352 (C=S), 1246 (C-N), 1182 (OCH3); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 3.70 (s, 3H, OCH3), 3.84 (s, 6H, OCH3), 7.22 (s, 1H, ArH), 7.64–7.58 (m, 4H, ArH), 7.67 (s, 1H, ArH), 7.71(d, 1H, J = 15.6, -C=HC-), 7.84 (s, 1H, NH2), 7.85 (d, 1H, J = 15.6, -C=HC-), 7.91 (s, 1H, NH2), 7.97 (s 2H, ArH), 8.02 (s, 1H, ArH), 8.43 (s, 1H, ArH), 8.51 (s, 1H, ArH), 9.28 (s, 1H, NH), 10.96 (s, 1H, =N-NH-C); LC-MS M/Z: 549 [M + H]+.

2-((E)-3-(4-chlorophenyl)-1-(3-((7-chloroquinolin-4-yl)amino)phenyl)allylidene)hydrazinecarbothioamide(8e)

Yield: 66%; m.p.: 212–214 °C; IR (KBr cm−1): 3338 (NH2), 1597 (C=C), 1350 (C=S), 1261 (C-N); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 7.21 (s, 1H, ArH), 7.46 (d, 1H, J = 15.6 Hz, -C=HC-), 7.52 (d, 2H, J = 8.4 Hz, ArH), 7.59 (d,1H, J = 15.6 Hz, -C=HC-), 7.61 (d, 2H, J = 8.4 Hz, ArH), 7.79–7.63 (m, 4H, ArH), 7.81 (s, 1H, NH2), 7.85 (s, 1H, ArH), 7.93 (s, 1H, NH2), 8.20 (s, 1H, ArH), 8.24 (s, 1H, ArH), 8.47(s, 1H, ArH), 9.29 (s, 1H, NH), 11.12 (s, 1H, =N-NH-C); LC-MS M/Z: 494 [M + H]+.

2-((E)-1-(3-((7-chloroquinolin-4-yl)amino)phenyl)-3-(4-fluorophenyl)allylidene)hydrazinecarbothioamide(8f)

Yield: 60%; m.p.: 234–236 °C; IR (KBr cm−1): 3358 (NH2), 1591 (C=C), 1350 (C=S); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 7.21 (s, 1H, ArH), 7.41–7.34 (m, 4H, ArH), 7.48 (d,1H, J = 15.6 Hz, -C=HC-), 7.57 (d, 2H, J = 8.4 Hz, ArH), 7.63 (d, 2H, J = 8.4 Hz, ArH), 7.76 (d, 1H, J = 15.6 Hz, -C=HC-), 7.88 (s, 1H, NH2), 7.83 (s, 1H, ArH), 7.95 (s, 1H, NH2), 8.22 (s, 1H, ArH), 8.31 (s, 1H, ArH), 8.45 (s, 1H, ArH), 9.25 (s, 1H, NH), 11.22 (s, 1H, =N-NH-C); LC-MS M/Z: 477 [M + H]+.

2-((E)-3-(4-bromophenyl)-1-(3-((7-chloroquinolin-4-yl)amino)phenyl)allylidene)hydrazinecarbothioamide(8 g)

Yield: 55%; m.p.: 238–240 °C; IR (KBr cm−1): 3364 (NH2), 1575 (C=C), 1355 (C=S); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 7.21 (s, 1H, ArH), 7.45–7.37 (m, 4H, ArH), 7.48 (d, 1H, J = 15.6 Hz, -C=HC-), 7.53 (d, 2H, J = 8.4 Hz, ArH), 7.68 (d, 2H, J = 8.4 Hz, ArH), 7.75 (d, 1H, J = 15.6 Hz, -C=HC-), 7.83 (s, 1H, NH2), 7.91 (s, 1H, ArH), 7.96 (s, 1H, NH2), 8.14 (s, 1H, ArH), 8.23 (s, 1H, ArH), 8.46 (s, 1H, ArH), 9.23 (s, 1H, NH), 11.21 (s, 1H, =N-NH-C); LC-MS M/Z: 538 [M + H]+.

2-((E)-1-(3-((7-chloroquinolin-4-yl)amino)phenyl)-3-(4-nitrophenyl)allylidene)hydrazinecarbothioamide(8 h)

Yield: 47%; m.p.: 218–220 °C; IR (KBr cm−1): 3356 (NH2), 1593 (NO2), 1550 (C=C), 1350 (C=S); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 7.20 (s, 1H, ArH), 7.52–7.43 (m, 4H, ArH), 7.56 (d, 2H, J = 8.4 Hz, ArH), 7.61 (d, 1H, J = 15.6 Hz, -C=HC-), 7.64 (d, 2H, J = 7.6 Hz, ArH), 7.69 (d, 1H, J = 15.6 Hz, -C=HC-), 7.72 (s, 1H, NH2), 7.96 (s, 1H, NH2), 8.16 (s, 1H, ArH), 8.31 (s, 1H, ArH), 8.36 (s, 1H, ArH), 8.48 (s, 1H, ArH), 9.68 (s, 1H, NH), 11.23 (s, 1H, =N-NH-C); LC-MS M/Z: 504 [M + H]+.

2-((E)-1-(3-((7-chloroquinolin-4-yl)amino)phenyl)-3-(4-hydroxyphenyl)allylidene)hydrazinecarbothioamide(8i)

Yield: 57%; m.p.: 250–242 °C; IR (KBr cm−1): 3478 (OH), 3360 (NH2), 1590 (C=C), 1361 (C=S), 1265 (C-N); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 7.2 (s, 1H, ArH), 7.20–7.15 (m, 4H, ArH), 7.25 (d, 1H, J = 15.6 Hz, -C=HC-), 7.38 (d, 2H, J = 8.4 Hz, ArH), 7.50 (d, 1H, J = 15.6 Hz, -C=HC-), 7.61 (d, 2H, J = 8.4 Hz, ArH), 7.76 (s, 1H, ArH), 7.87 (s, 1H, NH2), 7.93 (s, 1H, NH2), 7.97 (s, 1H, ArH), 8.31 (s, 1H, ArH), 8.43 (s, 1H, ArH), 9.35 (s, 1H, NH), 9.98 (s, 1H, OH), 11.22 (s, 1H, =N-NH-C); LC-MS M/Z: 475 [M + H]+.

2-((E)-1-(3-((7-chloroquinolin-4-yl)amino)phenyl)-3-(p-tolyl)allylidene)hydrazinecarboxamide(9a)

Yield: 55%; m.p.: 192–194 °C; IR (KBr cm−1): 3365 (NH2), 1690 (C=O), 1575 (C=C), 1261(C-N); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 2.61 (s, 3H, CH3), 6.73 (s, 2H, NH2), 7.16 (s, 1H, ArH), 7.33–7.21 (m, 4H, ArH), 7.36 (d, 1H, J = 15.6 Hz, -C=HC-), 7.41 (d, 2H, J = 8.4 Hz, ArH), 7.53 (d, 1H, J = 15.6 Hz, -C=HC-), 7.61 (d, 2H, J = 8.4 Hz, ArH), 7.82 (s, 1H, ArH), 7.91 (s, 1H, ArH), 8.32 (s, 1H, ArH), 8.41 (s, 1H, ArH), 9.33 (s, 1H, NH), 10.93 (s, 1H, =N-NH-C); LC-MS M/Z: 457 [M + H]+.

2-((E)-1-(3-((7-chloroquinolin-4-yl)amino)phenyl)-3-(4-methoxyphenyl) allylidene)hydrazinecarboxamide(9b)

Yield: 40%; m.p.: 188–190 °C; IR (KBr cm−1): 3365 (NH2), 1685 (C=O), 1590 (C=C), 1235 (OCH3); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 3.83 (s, 3H, OCH3), 6.69 (s, 2H, NH2), 7.52–7.43 (m, 4H, ArH), 7.65 (d, 2H, ArH), 7.68 (s, 1H, ArH), 7.71 (d, 1H, J = 15.6 Hz, -C=HC-), 7.75 (d, 1H, J = 15.6 Hz, -C=HC-), 7.81 (d, 2H, J = 8.8 Hz, ArH), 7.93 (s, 1H, ArH), 8.01 (s, 1H, ArH), 8.42 (s, 1H, ArH), 8.47 (s, 1H, ArH), 9.34 (s, 1H, NH), 11.10 (s, 1H, =N-NH-C); LC-MS M/Z: 473 [M + H]+.

2-((E)-1-(3-((7-chloroquinolin-4-yl)amino)phenyl)-3-(3,4-dimethoxyphenyl)allylidene)hydrazinecarboxamide(9c)

Yield: 51%; m.p.: 254–256 °C; IR (KBr cm−1): 3648 (NH2), 1680 (C=O), 1580 (C=C), 1215 (OCH3); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 3.86 (s, 3H, OCH3), 3.89 (s, 3H, −OCH3), 6.69 (s, 2H, −NH2), 7.53 (s, 1H, ArH), 7.68–7.59 (m, 3H, ArH), 7.71 (d, 1H, J = 15.6 Hz, -C=HC-), 7.79 (d, 1H, J = 15.6 Hz, -C=HC-), 7.91–7.83 (m, 3H, ArH), 7.94 (s, 1H, ArH), 8.10 (s, 1H, ArH), 8.23 (s, 1H, ArH), 8.49 (s, 1H, ArH), 8.51(s, H, ArH), 9.36 (s, 1H, NH), 11.13 (s, 1H, =N-NH-C); LC-MS M/Z: 503 [M + H]+.

2-((E)-1-(3-((7-chloroquinolin-4-yl)amino)phenyl)-3-(3,4,5-trimethoxyphenyl) allylidene)hydrazinecarboxamide(9d)

Yield: 60%; m.p.: 258–260 °C; IR (KBr cm−1): 3363 (NH2), 1690 (C=O), 1565 (C=C), 1248 (C-N), 1189 (OCH3); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 3.76 (s, 3H, OCH3), 3.85 (s, 6H, -OCH3), 6.79 (s, 2H, NH2), 7.41 (s, 1H, ArH), 7.81–7.7 (m, 4H, ArH), 7.92 (s, 1H, ArH), 7.83 (d, 1H, J = 15.6, -C=HC-), 7.87 (d, 1H, J = 15.6, -C=HC-), 7.96 (s 2H, ArH), 8.13 (s, 1H, ArH), 8.41 (s, 1H, ArH), 8.48 (s, 1H, ArH), 9.33 (s, 1H, NH), 10.83 (s, 1H, =N-NH-C); LC-MS M/Z: 533 [M + H]+.

2-((E)-3-(4-chlorophenyl)-1-(3-((7-chloroquinolin-4-yl)amino)phenyl)allylidene)hydrazinecarboxamide(9e)

Yield: 50%; m.p.: 226–228 °C; IR (KBr cm−1): 3354 (NH2), 1686 (C=O), 1583 (C=C), 1270 (C-N); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 6.73 (s, 2H, NH2), 7.13 (s, 1H, ArH), 7.48 (d, 1H, J = 15.6 Hz, -C=HC-), 7.53 (d, 2H, J = 8.4 Hz, ArH), 7.58 (d,1H, J = 15.6 Hz, -C=HC-), 7.65 (d, 2H, J = 8.4 Hz, ArH), 7.81–7.75 (m, 4H, ArH), 7.83 (s, 1H, ArH), 8.22 (s, 1H, ArH), 8.35 (s, 1H, ArH), 8.43 (s, 1H, ArH), 9.31 (s, 1H, NH), 10.86 (s, 1H, =N-NH-C); LC-MS M/Z: 477 [M + H]+.

2-((E)-1-(3-((7-chloroquinolin-4-yl)amino)phenyl)-3-(4-fluorophenyl)allylidene)hydrazinecarboxamide(9f)

Yield: 55%; m.p.: 198–200 °C; IR (KBr cm−1): 3360 (NH2), 1685 (C=O), 1595 (C=C); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 6.73 (s, 2H, NH2), 7.28 (s, 1H, ArH), 7.45–7.36 (m, 4H, ArH), 7.49 (d,1H, J = 15.6 Hz, -C=HC-), 7.53 (d, 2H, J = 8.4 Hz, ArH), 7.59 (d, 2H, J = 8.4 Hz, ArH), 7.75 (d, 1H, J = 15.6 Hz, -C=HC-), 7.95 (s, 1H, ArH), 8.26 (s, 1H, ArH), 8.35 (s, 1H, ArH), 8.46 (s, 1H, ArH), 9.29 (s, 1H, NH), 10.98 (s, 1H, =N-NH-C); LC-MS M/Z: 461 [M + H]+.

2-((E)-3-(4-bromophenyl)-1-(3-((7-chloroquinolin-4-yl)amino)phenyl)allylidene)hydrazinecarboxamide(9 g)

Yield: 60%; m.p.: 306–308 °C; IR (KBr cm−1): 3360 (NH2), 1686 (C=O), 1570 (C=C); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 6.75 (s, 2H, NH2), 7.14 (s, 1H, ArH), 7.49–7.38 (m, 4H, ArH), 7.52 (d, 1H, J = 15.6 Hz, -C=HC-), 7.63 (d, 2H, J = 8.4 Hz, ArH), 7.71 (d, 2H, J = 8.4 Hz, ArH), 7.79 (d, 1H, J = 15.6 Hz, -C=HC-), 7.93 (s, 1H, ArH), 8.22 (s, 1H, ArH), 8.29 (s, 1H, ArH), 8.45 (s, 1H, ArH), 9.27 (s, 1H, NH), 10.96 (s, 1H, =N-NH-C); LC-MS M/Z: 522 [M + H]+.

2-((E)-1-(3-((7-chloroquinolin-4-yl)amino)phenyl)-3-(4-nitrophenyl)allylidene)hydrazinecarboxamide(9 h)

Yield: 43%; m.p.: 246–248 °C; IR (KBr cm−1): 3360 (NH2), 1690 (C=O), 1595 (NO2), 1565 (C=C); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 6.72 (s, 2H, NH2), 7.20 (s, 1H, ArH), 7.53–7.48 (m, 4H, ArH), 7.56 (d 2H, J = 8.4 Hz, ArH), 7.65 (d, 2H, J = 7.6 Hz, ArH), 7.73 (d, 1H, J = 15.6 Hz, -C=HC-), 7.96 (d, 1H, J = 15.6 Hz, -C=HC-), 8.13 (s, 1H, ArH), 8.26 (s, 1H, ArH), 8.33 (s, 1H, ArH), 8.47 (s, 1H, ArH), 9.36 (s, 1H, NH), 10.87 (s, 1H, =N-NH-C); LC-MS M/Z: 488 [M + H]+.

2-((E)-1-(3-((7-chloroquinolin-4-yl)amino)phenyl)-3-(4-hydroxyphenyl)allylidene)hydrazinecarboxamide(9i)

Yield: 43%; m.p.: 234–236 °C; IR (KBr cm−1): 3362 (NH2), 1685 (C=O), 1593 (C=C), 1265(C-N); 1H-NMR (400 MHz, DMSO-d6) δ (ppm) = 6.67 (s, 2H, NH2), 7.10 (s, 1H, ArH), 7.23–7.14 (m, 4H, ArH), 7.27 (d, 1H, J = 15.6 Hz, -C=HC-), 7.49 (d, 2H, J = 8.4 Hz, ArH), 7.62 (d, 1H, J = 15.6 Hz, -C=HC-), 7.73 (d, 2H, J = 8.4 Hz, ArH), 7.98 (s, 1H, ArH), 8.15 (s, 1H, ArH), 8.36 (s, 1H, ArH), 8.46 (s, 1H, ArH), 9.29 (s, 1H, NH), 9.85 (s, 1H, OH), 10.93 (s, 1H, =N-NH-C); LC-MS M/Z: 459 [M + H]+.

Discussions

Chemistry

The reaction sequence employed for synthesis of the title compounds (6a-i), (7a-i), (8a-i), and (9a-i) are illustrated in Scheme 1. Initially, compounds 1-(4-((7-chloroquinolin-4-yl) amino)phenyl)ethanone (2) and 1-(3-((7-chloroquinolin-4-yl)amino) phenyl)ethanone (3) were prepared with slight modification on the basis of the previously reported methods [21]. Their IR spectra showed the appearance of characteristic band at around 3564–3651 cm−1 attributed to amino (NH) group and carbonyl (C=O) stretching frequency at around 1684 cm−1, while their 1H NMR spectrum indicated singlet signal at around δ 11.16 and 11.33 ppm for amine (NH) protons. Further, these compounds were confirmed by D2O exchange experiment. The key intermediate α, β-unsaturated ketones (chalcones) (4a-i) and (5a-i) were synthesized by reacting 1-(4-((7-chloroquinolin-4-yl)amino)phenyl)ethanone (2) or 1-(3-((7-chloroquinolin-4-yl)amino)phenyl)ethanone (3) with appropriate aldehydes by conventional base-catalyzed Claisen-Schmidt condensation. The IR spectra of the compounds (4a-i) and (5a-i) showed new band at 1530 cm−1 attributed to an alkene (C=C) group of α, β-unsaturated ketones. In addition, two sets of protons with a trans coupling constant (J = 16 Hz) were present at δ 7.72 and 8.05 ppm which confirms the completion of Claisen-Schmidt condensation reactions. Reaction of chalcones (4a-i) and (5a-i) with thiosemicarbazide and semicarbazide hydrochloride in dry isopropyl alcohol and the presence of glacial acetic acid for 36 h afforded the target thiosemicarbazone (6a-i) and (8a-i) and semicarbazone (7a-i) and (9a-i) derivatives respectively.

Scheme 1
scheme 1

Reagents and conditions: (a) dry methanol, reflux 9–10 h; (b) methanol, NaOH, THF, RT; (c) thiosemicarbazide or semicarbazide hydrochloride, dry isopropyl alcohol, and glacial acetic acid, reflux 36 h

Full size image

The structures of target compounds were established by using different spectroscopic techniques, including FTIR, NMR, and mass spectroscopy. The FTIR spectra of these compounds showed a medium to strong band for C=N stretch which appeared in the range 1620 to 1560 cm−1, C=S absorption band appeared at 1341 to 1356 cm−1, and semicarbazone derivatives showed C=O absorption band at 1661 to 1690 cm−1. In addition, FTIR spectra showed the appearance of characteristic bands at 3350 and 3290 cm−1 assignable for amino (NH) group, while their proton NMR spectrum indicated singlet at around δ 11.69–11.82 ppm for =N-NH-C- proton. The two amino (-NH2) protons appeared as two singlets in the range at 7.67 and 8.2 ppm. Finally, formation of these compounds was also evidenced by mass spectral data.

Biological activities

Antitubercular activity

The new thiosemicarbazone derivatives (6a-i) and (8a-i) and semicarbazide compounds (7a-i) and (9a-i) were evaluated against Mycobacterium tuberculosis (MTB) H37Rv (ATCC 27294) by using the microplate alamar blue assay (MABA) [22, 23]. The minimum inhibitory concentration (MIC) was determined for each derivative which was measured as the minimum concentration of the compound required to completely inhibit the bacterial growth. Isoniazid, pyrazinamide, and ciprofloxacin were used as standard drugs for comparison. Antitubercular activity results are summarized in Table 1. From the results, it was observed that among the tested compounds, the most active compounds 7c and 7 g exhibited Mycobacterium tuberculosis inhibition at 1.56 μM as compared to standard isoniazid (MIC = 1.56 μM). Three compounds 7a, 7i, and 9a inhibited MTB with MIC value of 6.25 μM, when compared to ciprofloxacin (MIC = 12.5 μM) and pyrazinamide (MIC = 50 μM). Nine compounds 6a, 6b, 6d, 6e, 7d, 7e, 8a, 8b, 9b, and 9c are found to be equally active as ciprofloxacin (12.5 μM). When compared to pyrazinamide (50.0 μM), most of the compounds were found to be more active, though 34 compounds were less potent than the first-line antitubercular drug isoniazid. Further, the following features of structure-activity relationship (SAR) of 7-chloro-N-phenylquinolin-4-amine derivatives (6a-i), (7a-i), (8a-i), and (9a-i) have been drawn against the inhibition of Mycobacterium tuberculosis. The thiosemicarbazide (6a-i) compounds with electron donating groups like 4-CH3 (6a), 4-OCH3 (6b), and 3,4,5-OCH3 (6d) have shown activity at 12.5 μM. When the same methoxy group was substituted at C-3 and C-4 positions (3,4-OCH3), the activity decreased to 25 μM as shown by compound 6c. Substitution of the C-4 position by a hydroxyl group (6i) further decreased the activity to 50 μM. Compounds 6f, 6g, and 6h with electron withdrawing groups like F, Br, and NO2 substituted at the C-4 position showed very weak activity (50 μM). However, the 4-chloro substituted compound 6e showed moderate activity (12.5 μM).

Table 1 Physical data and antimycobacterial activities of compound (6a-i), (7a-i), (8a-i), and (9a-i) against MTB H37Rv
Full size table

Among the semicarbazones (6a-i), compounds 7c and 7g displayed very promising activity at 1.56 μM, which was higher than the activities shown by their thiosemicarbazone counterparts. Compound 7a with an alkyl substituent (4-CH3) showed better activity at 6.25 μM as compared to 6a, whereas compound 7b with an alkoxy (4-OCH3) substituent displayed decreased activity as compared to 6b. Compounds with 3,4,5-(OCH3)3 group (7d) and 4-Cl group (7e) showed activities at 12.5 μM, similar to 6d and 6e. Compound 7g with an electronegative group at position C-4 proved to be the next most potent molecule by exhibiting inhibitory activity at 1.56 μM. Compounds 7h (4-NO2) and 7i (4-OH) displayed better inhibitory activities (12.5 μM and 6.25 μM) as compared to compounds 6h and 6i (50 μM). In the next series, the compound 8a with an electron donating 4-CH3 group has shown inhibitory activity at 12.5 μM. Other compounds 8b, 8c, and 8d with electron donating groups like 4-OCH3, 3,4-(OCH3)2, and 3,4,5-(OCH3)3 have shown inhibitory activity at 25 μM. Compounds with electron accepting substituents at the C-4 position like Cl (8e), Br (8 g), and NO2 (8 h) also showed activity at 25 μM, whereas compounds 8f (with substituent 4-F) and 8i (with substituent 4-OH) showed inhibitory activity at 50 μM. In these meta-substituted compounds, the most potent compound was 9a with a 4-methyl substituent exhibiting activity at 6.25 μM, which was better than that exhibited by 8a. Compounds 9b and 9c with electropositive substituents like 4-OCH3 and 3,4-OCH3 showed inhibitory activities at 12.5 μM, both being better than compound 8b and 8c with activity at 25 μM. Compounds 9d, 9e, 9g, and 9h displayed activities at 25 μM, which was similar to activities shown by 8d, 8e, 8g, and 8h. Compounds 9f and 9i with electronegative substituents 4-F and 4-OH showed better activities at 25 μM when compared with 8f and 8i. With respect to structure-activity relationship, the study revealed that the nature of carbazide and substituent(s) on the phenyl ring greatly affects the antitubercular activity. Thus, the comparative study of thiosemicarbazones and semicarbazones revealed that in general, semicarbazone compounds exhibited better inhibitory activity against Mycobacterium tuberculosis.

In recent years, drug likeness and rule of five models [25,26,27] are a novel approach for better understanding molecular parameters. The obtained results are showing that most of the synthesized compounds have better predicted value of hydrogen bond acceptor, polar surface area, and hydrogen bond donor. According to Lipinski’s rule of five, a biological therapeutic ligand should have number of hydrogen bond accepter atoms of 10 or less (N or O), number of hydrogen bond donor atoms of 5 or less, log p not more than 5, and molecular weight (MW) of 500 or less. The values of calculated drug scores revealed that most of the synthesized analogs have positive drug likeness score; interestingly, compound 7c exhibited promising inhibitory activity against Mycobacterium tuberculosis and highest drug likeness score Table 2.

Table 2 Molecular parameters of 7-chloro-4-aminoquinoline based semicarbazones and thiosemicarbazones (6a-i), (7a-i), (8a-i), and (9a-i)
Full size table

Cytotoxicity activity assay

The in vitro cytotoxicity of the active compounds (MIC ≤ 12.5 μM Mycobacterium tuberculosis) was evaluated against normal HDF cell line using 3-(4, 5-dimethylthiazo-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) cell proliferation assay. The graphical representation of the cell growth inhibition by the active compounds at a concentration of 50 μM is shown in Table 3. The assay data revealed that none of the active compounds are toxic to the normal cells thus proving the lack of general toxicity.

Table 3 Cytotoxicity of compounds against HDF (human dermal fibroblast) cell line
Full size table

Conclusion

In conclusion, a series of 7-chloro-N-phenylquinolin-4-amine derivatives (6a-i), (7a-i), (8a-i), and (9a-i) have been designed and synthesized. All synthesized derivatives underwent in vitro antitubercular evaluation against Mycobacterium tuberculosis H37Rv (MTB), and selected analogs were screened for cytotoxicity against normal HDF cell line by MTT cell proliferation assay. The results displayed that among the tested compounds, the most potent antitubercular activity was displayed by 7c and 7g with MIC = 1.56 μM and with low cytotoxicity. Thus, it can be concluded that 7-chloro-N-phenylquinolin-4-amines could be a promising approach for the design of new MTB inhibitory agents.

Availability of data and materials

All the data generated and analyzed during the study are included in the manuscript.

Change history

  • 04 February 2020

    Following publication of the original article [1], the authors reported an error in one of the authors’ names.

Abbreviations

DOTS:

Directly observed therapy short-course

INH:

Isoniazid

MIC:

Minimum inhibitory concentration

MTB:

Mycobacterium tuberculosis

MTT:

3-(4, 5-dimethylthiazo-2-yl)-2,5-diphenyl-tetrazolium bromide

PZA:

Pyrazinamide

RIF:

Rifampicin

TB:

Tuberculosis

References

  1. World Health Organization. Global Tuberculosis Report 2018 and Global Tuberculosis Report (2018) https://www.who.int/tb/publications/global_report/en/. Accessed 15 July 2019

    Google Scholar 

  2. Bass JB, Farer LS, Hopewell PC, Obrien R, Jacobs RF, Ruben F, Snder DE, Thornton G (1994) Treatment of tuberculosis and tuberculosis infection in adults and children. American Thoracic Society and the centers for Disease Control and Prevention. Am J Respir Crit Care Med 149:1359–1374. https://doi.org/10.1164/ajrccm.149.5.8173779

    Article  PubMed  Google Scholar 

  3. Davies PDO, Yew WW (2003) Recent developments in treatment of tuberculosis. Expert Opin Investig Drugs 12:1297–1312. https://doi.org/10.1517/13543784.12.8.1297

    Article  CAS  PubMed  Google Scholar 

  4. Tiberi S, Munoz-Torrico M, Duarte R, Dalcolmo M, D’Ambrosio L, Migliori GB (2018) New drugs and perspectives for new anti-tuberculosis regimens. Pulmonol 24:86–98. https://doi.org/10.1016/j.rppnen.2017.10.009

    Article  CAS  Google Scholar 

  5. Ferrer R, Lobo G, Gamboa N, Rodrigues J, Abramjuk C, Jung K, Lein M, Charris JE (2009) Synthesis of ((7-chloroquinolin-4-yl)amino)chalcones: potential antimalarial and anticancer agents. Sci Pharm 77:725–741. https://doi.org/10.3797/scipharm.0905-07

    Article  CAS  Google Scholar 

  6. Kumar A, Srivastava K, Kumar SR, Siddiqi MI, Puri SK, Sexena JK, Chauhan MS (2011) 4-anilinoquinoline triazines: a novel class of hybrid antimalarial agents. Eur J Med Chem 46:676–690. https://doi.org/10.1016/j.ejmech.2010.12.003

    Article  CAS  PubMed  Google Scholar 

  7. Lu CM, Chen YL, Chen HL, Chen CA, Lu PJ, Yang CN (2010) Synthesis and antiproliferative evaluation of certain indolo(3,2-c)quinoline derivatives. Bio Org Med Chem 18:1948–1957. https://doi.org/10.1016/j.bmc.2010.01.033

    Article  CAS  Google Scholar 

  8. Abonia R, Insuasty D, Castillo J, Insuasty B, Quiroga J, Nogueras M, Cobo J (2012) Synthesis of novel quinoline-2-one based chalcones of potential anti-tumor activity. Eur J Med Chem 57:29–40. https://doi.org/10.1016/j.ejmech.2012.08.039

    Article  CAS  PubMed  Google Scholar 

  9. Chia EW, Pearce AN, Berridge MV, Larsen L, Perry NB, Sansom CE, Godfrey CA, Hanton LR, Lu GL, Walton M, Denny WA, Webb VL, Copp BR, Harper JL (2002) Synthesis and anti-inflammatory structure-activity relationships of thiazine-quinoline-quinones: inhibitors of the neutrophil respiratory burst in a model of acute gouty arthritis. Bioorg Med Chem 16:9432–9442. https://doi.org/10.1016/j.bmc.2008.09.052

    Article  CAS  Google Scholar 

  10. Zarghi A, Ghodsi R, Azizi E, Daraie B, Hedayati M, Dadrass OG (2009) Synthesis and biological evaluation of new 4-carboxyl quinoline derivatives as cyclooxygenase-2 inhibitors. Bio Org Med Chem 17:5312–5317. https://doi.org/10.1016/j.bmc.2009.05.084

    Article  CAS  Google Scholar 

  11. Jablonski JJ, Basu D, Engel DA, Geysen HM (2012) Design, synthesis, and evaluation of novel small molecule inhibitors of the influenza virus protein NS1. Bio Org Med Chem 20:487–497. https://doi.org/10.1016/j.bmc.2011.10.026

    Article  CAS  Google Scholar 

  12. Chen YL, Tang J, Kesler MJ, Sham YY, Vince R, Geraghty RJ, Wang Z (2012) The design, synthesis and biological evaluations of C-6 or C-7 substituted 2-hydroxyisoquinoline-1,3-diones as inhibitors of hepatitis C virus. Bio Org Med Chem 20:467–479. https://doi.org/10.1016/j.bmc.2011.10.058

    Article  CAS  Google Scholar 

  13. Garudachari B, Satyanarayana MN, Thippeswamy B, Shivakumar CK, Shivananda HN, Hegde G, Isloor AM (2012) Synthesis, characterization and antimicrobial studies of some new quinoline incorporated benzimidazole derivatives. Eur J Med Chem 54:900–906. https://doi.org/10.1016/j.ejmech.2012.05.027

    Article  CAS  PubMed  Google Scholar 

  14. Eswaran S, Adhikari AV, Shetty NS (2009) Synthesis and antimicrobial activities of novel quinoline derivatives carrying 1,2,4-triazole moiety. Eur J Med Chem 44:4637–4647. https://doi.org/10.1016/j.ejmech.2009.06.031

    Article  CAS  PubMed  Google Scholar 

  15. Musiol R, Jampilek J, Buchta V, Silva L, Niedbala H, Podeszwa B, Palka A, Maniecka KM, Oleksyn B, Polanski J (2006) Antifungal properties of new series of quinoline derivatives. Bioorg Med Chem 14:3592–3598. https://doi.org/10.1016/j.bmc.2006.01.016

    Article  CAS  PubMed  Google Scholar 

  16. Fiorito J, Saeed F, Zhan SA, Feng Y, Francis YL, Rao S, Thakkar DM, Deng SH, Landry DW, Arancio O (2013) Synthesis of quinoline derivatives: discovery of a potent and selective phosphodiesterase 5 inhibitor for the treatment of Alzheimer’s disease. Eur J Med Chem 60:285–294. https://doi.org/10.1016/j.ejmech.2012.12.009

    Article  CAS  PubMed  Google Scholar 

  17. Marella A, Tanwar OP, Shah R, Ali MR, Srivastava S, Akhter M, Shaquiquzzaman M, Alam MM (2013) Quinoline: a versatile heterocyclic. Saud Pharm J 21:1–12. https://doi.org/10.1016/j.jsps.2012.03.002

    Article  Google Scholar 

  18. Rangappa SK, Siddappa AP (2014) Quinoline: a promising antitubercular target. Biomed Pharmacother 68:1161–1175. https://doi.org/10.1016/j.biopha.2014.10.007

    Article  CAS  Google Scholar 

  19. Jallapally A, Adbla D, Yogeeswari P, Sriam D, Kantevari S (2014) 2-Butyl-4-chloroimidazole based substituted piperazine-thiosemicarbazone hybrids as potent inhibitors of Mycobacterium tuberculosis. Bioorg Med Chem Lett 24:5520–2524. https://doi.org/10.1016/j.bmcl.2014.09.084

    Article  CAS  PubMed  Google Scholar 

  20. Pavan FR, Mira PIS, Leite SRA, Deflon VM, Batista AA, Sato DN, Franzblu SG, Leite CQF (2010) Thiosemicarbazones, semicarbazones, dithiocarbazates and hydrazide/hydrazones: anti-mycobacterium tuberculosis activity and cytotoxicity. Eur J Med Chem 45:1898–1905. https://doi.org/10.1016/j.ejmech.2010.01.028

    Article  CAS  PubMed  Google Scholar 

  21. Sharma M, Chaturvedi V, Manju YK, Batnagar S, Shrivastava K, Puri SK, Chauhan PMS (2009) Substituted quinolinyl chalcones and quinolinyl pyrimidines as a new class of anti-infective agents. Eur J Med Chem 44:2081–2091. https://doi.org/10.1016/j.ejmech.2008.10.011

    Article  CAS  PubMed  Google Scholar 

  22. Franzblau SG, Witzig RS, McLaughlin JC, Torres P, Madico G, Hernandez A, Degnan MT, Cook MB, Quenzer VK, Ferguson RM, Gilman RH (1998) Rapid, low-technology MIC determination with clinical mycobacterium tuberculosis isolates by using the microplate alamar blue assay. J Clin Microbiol 36:362–366

    Article  CAS  Google Scholar 

  23. Alegaon SG, Alagawadi KR, Sonkusare PV, Chaudhary SM, Dadwe DH, Shah AS (2012) Novel imidazo(2,1-b)(1,3,4) thiadiazole carrying rhodanine-3-acetic acid as potential antitubercular agents. Bioorg Med Chem Lett 22:1917–1921. https://doi.org/10.1016/j.bmcl.2012.01.052

    Article  CAS  PubMed  Google Scholar 

  24. Mosmann T (1983) Rapid colorimetric assay for cellular growth and survival: application to proliferation and cytotoxicity assays. J Immunol Methods 65:55–63. https://doi.org/10.1016/0022-1759(83)90303-4

    Article  CAS  PubMed  Google Scholar 

  25. Lipinski CA, Lombardo F, Dominy BW, Feeney PJ (2001) Experimental and computational approaches to estimate solubility and permeability in drug discovery and development settings. Adv Drug Deliv Rev 46:3–26

    Article  CAS  Google Scholar 

  26. Cheminformatics M Bratislava. Slovak Republic http://www.molinspiration.com/services/properties.html. Accessed 10 July 2019

  27. Drug-Likeness and molecular property prediction. http://molsoft.com/mprop/ Accessed 10 July 2019

Download references

Acknowledgements

The authors are grateful to Principal, KLE College of Pharmacy, Belagavi, for providing necessary facilities for the research. The authors are also grateful to the NMR Research center, IISC, Bangalore, India, for providing the spectral data.

Funding

No funding was obtained for this study.

Author information

Authors and Affiliations

  1. Department of Pharmaceutical Chemistry, KLE College of Pharmacy, Belagavi, KLE Academy of Higher Education and Research, Belagavi, Karnataka, 590 010, India

    Shankar Alegaon, Kamlesh Kashniyal, Sanket Kuncolienkar, Rohini Kavalapure, Preeti Salve, Mahesh Palled & Shailendra Suryawanshi

  2. Department of Pharmacognosy and Phytochemistry, KLE College of Pharmacy, Belagavi, KLE Academy of Higher Education and Research, Belagavi, Karnataka, 590 010, India

    Sunil Jalalpure

  3. Dr. Prabhakar Kore Basic Science Research Center, KLE Academy of Higher Education and Research, Belagavi, Karnataka, 590 010, India

    Sunil Jalalpure

Authors
  1. Shankar Alegaon
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Kamlesh Kashniyal
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Sanket Kuncolienkar
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Rohini Kavalapure
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Preeti Salve
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Mahesh Palled
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Shailendra Suryawanshi
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Sunil Jalalpure
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

All authors have read and approved the manuscript. SA designed and outlined and contributed to the characterization of the study. KK, SK, RK, and PS managed the synthetic application. MP, SA, and SS contributed to the analytical work.

Corresponding author

Correspondence to Shankar Alegaon.

Ethics declarations

Ethics approval and consent to participate

Not applicable

Consent for publication

Not applicable

Competing interests

The authors declare that they have no competing interests.

Additional information

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

The original version of this article was revised: author Sunil Jalalpure’s name was incorrectly published as Sulin Jalalpure.

Additional file

Additional file 1.

Supplementary material.

Rights and permissions

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Alegaon, S., Kashniyal, K., Kuncolienkar, S. et al. Synthesis and biological evaluation of some 4-aminoquinoline derivatives as potential antitubercular agents. Futur J Pharm Sci 6, 2 (2020). https://doi.org/10.1186/s43094-019-0016-7

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1186/s43094-019-0016-7

Keywords

  • Thiosemicarbazones
  • Semicarbazones
  • Quinoline
  • Antitubercular
  • Cytotoxicity