Synthesis and antitubercular activity of 7-chloro-4-quinolinylhydrazones derivatives

Article abstract of DOI:10.1016/j.bmcl.2009.09.098

A series of twenty-one 7-chloro-4-quinolinylhydrazones (3a-u) have been synthesized and evaluated for their in vitro antibacterial activity against Mycobacterium tuberculosis H₃₇Rv. The compounds 3f, 3i and 3o were non-cytotoxic and exhibited a

Full text of DOI:10.1016/j.bmcl.2009.09.098

Bioorganic & Medicinal Chemistry Letters 19 (2009) 6272–6274
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Synthesis and antitubercular activity of 7-chloro-4-quinolinylhydrazones
derivatives
André L. P. Candéa a, Marcelle de L. Ferreira a,b, Karla C. Pais a,b, Laura N. de F. Cardoso a, Carlos R. Kaiser b,
Maria das Graças M. de O. Henriques a, Maria C. S. Lourenço c, Flávio A. F. M. Bezerra c,
Marcus V. N. de Souza a,
*
a FioCruz-Fundação Oswaldo Cruz, Instituto de Tecnologia em Fármacos-Far Manguinhos. Rua Sizenando Nabuco, 100, Manguinhos, 21041-250 Rio de Janeiro, RJ, Brazil
b Departamento de Química Orgânica, Instituto de Química, Universidade Federal do Rio de Janeiro, CP 68563, 21945-970 Rio de Janeiro, Brazil
c Instituto de Pesquisas Clínica Evandro Chagas, IPEC, Av. Brasil, 4365 Manguinhos, Rio de Janeiro, Brazil
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of twenty-one 7-chloro-4-quinolinylhydrazones (3a–u) have been synthesized and evaluated for
their in vitro antibacterial activity against Mycobacterium tuberculosis H37Rv. The compounds 3f, 3i and 3o
were non-cytotoxic and exhibited an important minimum inhibitory concentration (MIC) activity
Received 30 August 2009
Revised 24 September 2009
Accepted 25 September 2009
Available online 29 September 2009
(2.5
picin (2.0
leads for anti-TB compounds.
l
g/mL), which can be compared with that of the first line drugs, ethambutol (3.12
lg/mL) and rifam-
l
g/mL). These results can be considered an important start point for the rational design of new
Keywords:
Tuberculosis
Quinoline
Drugs
Ó 2009 Elsevier Ltd. All rights reserved.
Tuberculosis (TB) is still an important worldwide public health
problem. According to statistics, more than two billion people,
equal to one third of the world’s total population, are infected with
TB bacilli (Mycobacterium tuberculosis) and a total of 1.77 million
people died from TB in 2007.1
class of heterocyclic compounds found in many synthetic and nat-
ural products with a wide variety of pharmacological activities,
such as antiviral, anticancer, antibacterial, antifungal, antiobesity
and anti-inflammatory.3
Another important application of this nucleus in TB drug dis-
covery is the diarylquinoline TMC207, which has a new mecha-
nism of anti-TB activity, based on the inhibiting of mycobacterial
adenosine triphosphate (ATP) synthase. This enzyme is responsible
for energy source for the bacterium. The results of the phase 2
studies of this compound show that the adverse side effects of
TMC207 are moderate and this drug may shorten the time of treat-
ment for MDR-TB.4
The emergence of drug-resistant TB is an important fact that
made the resurgence of TB especially alarming. According the
World Health Organization (WHO), there are two types of resistant
strains: multidrug-resistant TB (MDR-TB, resistant to isoniazid and
rifampicin) and extensively drug-resistant TB (XDR-TB, resistant
to all the most effective drugs). The spread of MDR-TB could cost
between 100 and 1400 times the available treatment costs
and further it threatens to make TB incurable. Currently, MDR-TB
represents, on average, 5.3% of all TB cases. Furthermore, WHO
estimates 490,000 MDR-TB cases emerge every year, with more
than 110,000 deaths. The true scale of XDR-TB is unknown due
to the lack of necessary equipment in many countries and capacity
to accurately diagnose it. However, it is estimated that there are
around 40,000 cases per year.2
Another reason to explore the potential antitubercular activity
of quinoline derivatives is a recent study developed by our
research group, which showed that some 7-chloro-4-amino-quino-
line derivatives exhibited a significant activity (MIC = 12.5–3.12
mL), when compared to first line drugs such ethambutol (MIC =
3.12
g/mL).5 In thisstudy, we haveobservedthatthechlorineatom
lg/
l
at C-7 position in the quinoline nucleus is essential for the anti-TB
activity. Because of that, we decided to synthesize different 7-
chloro-quinoline compounds, which are described in this article.
In this context, in our continuous program in the search for new
candidates to antitubercular agents, we proposed the synthesis
of some hydrazones, containing the 7-chloro-quinoline moiety that
was designed by molecular hybridization. Due to its synthetic and
biological versatility, hydrazones are attractive target compounds
Due to the high impact of MDR and recently XDR in TB treat-
ment, there is an urgent need for new drugs to treat this disease
efficiently. In this context, the quinoline nucleus is an important
* Corresponding author. Tel.: +55 2139772404; fax: +55 2125602518.
E-mail address: marcos_souza@far.fiocruz.br (M.V.N. de Souza).
0960-894X/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2009.09.098

A. L. P. Candéa et al. / Bioorg. Med. Chem. Lett. 19 (2009) 6272–6274
6273
O
H
hydrazones groups (C). This modification aims to investigate the
influence of some substituents at the phenyl ring (B) on in vitro
biological activity of these compounds (Fig. 1).
NHNH2
The synthetic route for the preparation of 7-chloro-4-quin-
olinylhydrazones derivatives 3a–u is summarized in Scheme 1.
Firstly, 7-chloro-4-hydrazinoquinoline 2 was prepared from 4,7-
dichloroquinoline 1 using hydrazine hydrate (80%) in ethanol un-
der reflux.13 After that, the compounds 3a–u were obtained
through reaction between the compound 2 and appropriated benz-
aldehydes as it is described in the general procedure (Table 1).14 In
general, the 1H NMR spectra showed the characteristic signal for
the N@CH proton at 8.37–8.81 ppm. Furthermore, the IR spectra
showed N–H and N@C stretching vibrations at 3197–3247 and
1570–1585 cmÀ1, respectively.
Cl
N
R
A
B
Molecular
hybridization
R
C
N
HN
The antimycobacterial activities of the derivatives 3a–u were
assessed against M. tuberculosis ATCC 2729418 using the microplate
Alamar Blue assay (MABA)19 (Table 1). This methodology is non-
toxic, uses a thermally-stable reagent and shows good correlation
with proportional and BACTEC radiometric methods.20,21 These re-
sults showed that compounds 3a–c, 3e–g, 3i–j, 3m–o and 3s
Cl
N
Figure 1. Design concept of 7-chloro-4-quinolinylhydrazones derivatives.
exhibited an antimycobacterial activity between 12.5 and 2.5
mL. Therefore, these compounds were selected for evaluation of
lg/
for new drug development. In literature, many pharmacological
activities have been associated to hydrazones, such as antidepres-
sant, anticonvulsant, anti-inflammatory, antimicrobial6 and antitu-
bercular activities.7–12 For this reason, the design concept of these
compounds explores the introduction of monosubstituted benzal-
dehydes moieties (A) into 7-chloro-quinoline core (B) to obtain
´
their cytotoxicities by Mosmanss assay.
The cellular viability in the presence and absence of the test
compounds 3a–c, 3e–g, 3i–j, 3m–o and 3s was determined by
´
Mosmanss MTT (3-(4.5-demethylthylthiazol-2-yl)-2.5-dimethyl-
R2
R1
R3
R4
N
HN
Cl
N
NHNH2
R5
b
a
Cl
N
Cl
Cl
N
1
2
3a-u
Scheme 1. Reagents and conditions: (a) N2H4ÁH2O (80%), EtOH, 80 °C, 2 h, 80%; (b) corresponding benzaldehyde, EtOH, rt, 4–24 h, 64–91%.
Table 1
Antimycobacterial activities, melting points, clogP measurements, and yields of 7-chloro-4-quinolinylhydrazones derivatives 3a–u
a
b
Entry
Substituents
Yield (%)
Mp (°C)
MIC
(l
g/mL)
cLog P
3a
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
3m
3n
3o
3p
R1 = Cl; R2 = R3 = R4 = R5 = H
91
64
82
81
77
84
74
80
74
82
79
80
82
77
85
72
76
70
77
82
70
—
192–19415
24015
6.25
3.12
12.5
>100.0
3.12
2.50
3.12
>100.0
2.50
2.50
>100.0
6.25
3.25
3.25
2.5
>100.0
>100.0
>100.0
6.25
>100.0
>100.0
3.25
6.28
6.31
6.33
6.41
6.44
6.46
5.77
5.79
5.82
5.59
5.15
5.17
5.66
6.87
5.71
5.56
5.59
5.61
5.38
5.41
5.65
À0.72
R
R
R
R
R
2 = Cl; R1 = R3 = R4 = R5 = H
3 = Cl; R1 = R2 = R4 = R5 = H
1 = Br; R2 = R3 = R4 = R5 = H
2 = Br; R1 = R3 = R4 = R5 = H
3 = Br; R1 = R2 = R4 = R5 = H
225–22615
273–275
189–191
198–199
234–23615
22515
R1 = F; R2 = R3 = R4 = R5 = H
R
R
R
R
R
R
R
2 = F; R1 = R3 = R4 = R5 = H
3 = F; R1 = R2 = R4 = R5 = H
1 = OH; R2 = R3 = R4 = R5 = H
2 = OH; R1 = R3 = R4 = R5 = H
3 = OH; R1 = R2 = R4 = R5 = H
1 = OMe; R2 = R3 = R4 = R5 = H
2 = OMe; R1 = R3 = R4 = R5 = H
245–24615
233–23516
270
219–220
186–188
117–119
144–145
253
R3 = OMe; R1 = R2 = R4 = R5 = H
R
R
R
R
R
R
1 = NO2; R2 = R3 = R4 = R5 = H
2 = NO2; R1 = R3 = R4 = R5 = H
3 = NO2; R1 = R2 = R4 = R5 = H
2 = CN; R1 = R3 = R4 = R5 = H
3 = CN l; R1 = R2 = R4 = R5 = H
1 = R2 = R3 = R4 = R5 = H
3q
3r
3s
3t
28117
188–190
212–214
230–231
223–22513
—
3u
Ethambutol
—
a
Minimum inhibitory concentration.
Calculated using www.molinspiration.com.
b

6274
A. L. P. Candéa et al. / Bioorg. Med. Chem. Lett. 19 (2009) 6272–6274
Table 2
bacterial activity evaluation and twelve derivatives (3a–c, 3e–g,
3i–j, 3m–o and 3s) exhibited MIC between 12.5 and 2.5 g/mL.
Therefore, these compounds were selected to evaluation of their
Data of the cellular viability for a macrophage cell line J774 (ATCC TIB-67TM) by
Mosmans´s assay
l
Compound
% Cell viability/dose (lg/mL)
´
cytotoxicities by Mosmanss assay with non-infected and BCG-in-
fected macrophages. Among these derivatives, only 3c, 3f, 3i and
3o were not cytotoxic to host cells in the effective concentrations
to inhibit the growth M. tuberculosis. Furthermore, the compounds
1
10
100
3a
3b
3c
3e
3f
3g
3i
3j
3l
3m
3n
3o
83
7
5
100
60
100
5
100
97
5
4
4
100
4
93
3
6
96
3
91
3
97
88
3
3
2
100
4
82
100
100
88
100
77
100
100
86
100
87
3f, 3i and 3o exhibited a significant activity (2.5
pared with first line drugs such as ethambutol (MIC = 3.12
l
g/mL) when com-
g/mL)
l
and could be considered a good start point to find new lead com-
pounds in the fight against multidrug-resistant tuberculosis.
References and notes
1. http://www.who.int/tb/en/.
2. http://www.who.int/tb/challenges/mdr/en/index.html.
3. Musiol, R.; Jampilek, J.; Buchta, V.; Silva, L.; Niedbala, H.; Podeszwa, B.; Palka,
A.; Majerz-Maniecka, K.; Oleksyn, B.; Polanski, J. Bioorg. Med. Chem. 2006, 14,
3592.
100
89
100
3s
Ethambutol
4. Diacon, A. H.; Pym, A.; Grobusch, M.; Patientia, R.; Rustomjee, R.; Page-Shipp, L.,
et al N. Eng. J. Med. 2009, 360, 2397.
5. De Souza, M. V. N.; Pais, K. C.; Kaiser, C. R.; Peralta, M. A.; Ferreira, M. L.;
Lourenço, M. C. S. Bioorg. Med. Chem. 2009, 17, 1474.
Table 3
Data of the cellular viability for a macrophage cell line J774 infected (ATCC TIB-67TM
)
6. Rollas, S.; Küçükgüzel, Sß. G. Molecules 2007, 12, 1910.
with BCG by Mosmans’s assay
7. Junior, I. N.; Lourenço, M. C. S.; Henriques, M. G. M. O.; Ferreira, B.; Vasconcelos,
T. R. A.; Peralta, M. A.; De Oliveira, P. S. M.; Wardell, S. M. S. V.; De Souza, M. V.
N. Lett. Drug Des. Discovery 2005, 2, 563.
8. Wardell, S. M. S. V.; De Souza, M. V. N.; Wardell, J. L.; Low, J. N.; Glidewell, C.
Acta Crystallogr., Sect. B: Struct. Sci. 2007, 63, 879.
Compound
% Cell viability/dose (lg/mL)
1
10
100
3c
3f
3i
3o
100
100
100
100
92
100
100
100
100
88
90
85
93
88
85
9. Carvalho, S. A.; da Silva, E. F.; de Souza, M. V. N.; Lourenço, M. C. S.; Vicente, F. R.
Bioorg. Med. Chem. Lett. 2008, 18, 538.
10. Lourenço, M. C. S.; Ferreira, M. L.; De Souza, M. V. N.; Peralta, M. A.;
Vasconcelos, T. R. A.; Henriques, M. G. M. O. Eur. J. Med. Chem. 2008, 43, 1344.
11. Ferreira, M. L.; Cardoso, L. N. F.; Gonçalves, R. S. B.; Da Silva, E. T.; Lourenço, M.
C. S.; Vicente, F. R.; De Souza, M. V. N. Lett. Drug. Des. Discovery 2008, 5, 137.
12. Lourenço, M. C.; De Souza, M. V. N.; Pinheiro, A. C.; Ferreira, M. L.; Gonçalves, R.
S. B.; Nogueira, T. C. M.; Peralta, M. A. ARKIVOC 2007, XV, 181.
13. Al-Sha’alan, N. H. Molecules 2007, 12, 1080.
14. General procedure for the synthesis of 7-chloro-4-quinolinylhydrazones derivatives
3a–u: The compounds 3a–u were obtained by reaction between compound 2
(0.2 g, 1.03 mmol) and the appropriate benzaldehyde (1.24 mmol) in ethanol
(5 mL). After stirring for 4–24 h at room temperature, the resulting mixture
was concentrated under reduced pressure and the residue purified by washing
with cold Et2O (3 Â 10 ml), leading to the pure derivatives (3a–u) as solids in
64–91% yields.
15. Pellerano, C.; Savini, L.; Fiorini, I. Atti Accad. Fisiocritic Siena 1976, 8, 43.
16. El-Behery, M.; El-Twigry, H. Spectrochim. Acta, Part A 2007, 66, 28.
17. Thomas, J.; Berkoff, C. E.; Flagg, W. B.; Gallo, J. J.; Haff, R. F.; Pinto, C. A.;
Pellerano, C.; Savini, L. J. Med. Chem. 1975, 18, 245.
18. Canetti, J.; Rist, E.; Grosset, R. Pneumology 1963, 27, 217.
19. Franzblau, S. G.; Witzig, R. S.; McLaughlin, J. C.; Torres, P.; Madico, G.;
Hernandez, A.; Degnan, M. T.; Cook, M. B.; Quenzer, V. K.; Ferguson, R. M.;
Gilman, R. H. J. Clin. Microbiol. 1998, 36, 362.
Ethambutol
tetrazolium bromide; Merck) microcultured tetrazolium assay.22,23
The results were represented as percentage cell viability (Table 2).
This table shows that the compounds 3b, 3c, 3d, 3i and 3o did
not kill more than 5% of the host cells in the minimum concentra-
tion tested. Hence, these compounds were selected to be tested on
macrophages infected with Mycobaterium bovis Bacillus Calmette-
Guerin (BCG) (Table 3).
The purpose of this test is to evaluate the action of these com-
pounds against macrophages that show their metabolism changed
after infection. Then, all the derivatives 3c, 3d, 3i and 3o were not
cytotoxic once they did not kill more than 5% of the cells at the
minimum concentration tested. It is important be mentioned that
theses compounds are less cytotoxic towards normal cells than the
20. Vanitha, J. D.; Paramasivan, C. N. Mycobacteriology 2004, 49, 179.
21. Reis, R. S.; Neves, I., Jr.; Lourenço, S. L. S.; Fonseca, L. S.; Lourenço, M. C. S. J. Clin.
Microbiol. 2004, 42, 2247.
22. Souza, M. C.; Siani, A. C.; Ramos, M. F. S., Jr.; Limas, O. M.; Henrique, M. G. M. O.
Pharmazie 2003, 58, 582.
first line drug ethambutol in 1 and 10 lg/mL.
In conclusion, the synthesis of twenty-one 7-chloro-4-quin-
olinylhydrazones derivatives 3a–u was performed in good yields
(64–91%). Among them eleven are new compounds (3d–f, 3k–n,
3p and 3r–t). All these compounds were submitted to antimyco-
23. Carvalho, M. V.; Monteiro, C. P.; Siani, A. C.; Valente, L. M. M.; Henriques, M. G.
M. O. Inflammopharmacology 2006, 14, 48.