Synthesis of some bioactive 2-bromo-5-methoxy-N′-[4-(aryl)-1,3-thiazol-2-yl]benzohydrazide derivatives

Article abstract of DOI:10.1016/j.ejmech.2006.09.010

Eight novel 2-bromo-5-methoxy-N′-[4-(aryl)-1,3-thiazol-2-yl]benzohydrazide derivatives were prepared and characterized by analytical and spectral analyses. All the compounds were screened for their analgesic, antifungal and antibacterial activities and th

Full text of DOI:10.1016/j.ejmech.2006.09.010

European Journal of Medicinal Chemistry 42 (2007) 425e429
http://www.elsevier.com/locate/ejmech
Preliminary communication
0
Synthesis of some bioactive 2-bromo-5-methoxy-N -[4-(aryl)-
1
,3-thiazol-2-yl]benzohydrazide derivatives
a
K.K. Vijaya Raj , B. Narayana , B.V. Ashalatha ,
a,*
a
b
N. Suchetha Kumari , B.K. Sarojini
c
a
Department of Post-Graduate Studies and Research in Chemistry, Mangalore University, Mangalagangotri, Mangalore 574 199, Karnataka, India
b
Department of Biochemistry, K.S. Hegde Medical Academy, Deralakatte, Mangalore 574 162, Karnataka, India
c
Department of Chemistry, P.A. College of Engineering, Nadupadvu, Mangalore 574 153, Karnataka, India
Received 9 April 2006; received in revised form 31 July 2006; accepted 7 September 2006
Available online 30 October 2006
Abstract
0
Eight novel 2-bromo-5-methoxy-N -[4-(aryl)-1,3-thiazol-2-yl]benzohydrazide derivatives were prepared and characterized by analytical and
spectral analyses. All the compounds were screened for their analgesic, antifungal and antibacterial activities and three of the compounds were
screened for antiproliferative activity. Two of the newly synthesized compounds exhibited promising analgesic activity and one compound ex-
hibited in vitro antiproliferative activity.
Ó 2006 Elsevier Masson SAS. All rights reserved.
Keywords: Synthesis; Bioactive; 2-Bromo-5-methoxy; Thiazolylbenzohydrazide
1
. Introduction
antibacterial activities. Three of the compounds have also
been screened for their antiproliferative activity.
Antimicrobial activity of thiazole derivatives has been ex-
tensively studied by many researchers [1e3]. Organic com-
pounds bearing thiazoles of different pharmacodynamic
nuclei were found to possess antiinflammatory activity [4,5].
Compounds containing thiazole ring system are used as antivi-
ral agents and some are used as pesticides [6,7]. Antitumor
and cytotoxic activities of thiazole derivatives are well known
in the literature [8e10]. As a continuation of our research
2
. Results and discussion
2.1. Chemistry
Methyl-2-bromo-5-methoxybenzoate was converted to 2-
bromo-5-methoxybenzoic acid hydrazide [19,20], which was
then converted to 1-(2-bromo-5-methoxybenzoyl) thiosemi-
carbazide 1 by treating with KSCN and conc. HCl. 1-(2-
Bromo-5-methoxybenzoyl) thiosemicarbazide 1 was then re-
fluxed with different aromatic acyl bromides 2aeh in ethanol
work to explore potent bioactive thiazole containing molecules
0
[
11e13], eight new 2-bromo-5-methoxy-N -[4-(aryl)-1,3-thia-
zol-2-yl]benzohydrazide derivatives were prepared and char-
acterized by analytical and spectral methods. All the eight
compounds were screened for their analgesic, antifungal and
0
to obtain 2-bromo-5-methoxy-N -[4-(aryl)-1,3-thiazol-2-yl]-
benzohydrazide derivatives 3aeh, Scheme 1. All the com-
pounds were isolated in good yield after recrystallisation
from methanoleDMF mixture. Few compounds were charac-
terized by IR, H NMR and mass spectral analyses. Character-
ization data of the compounds are given in Table 1.
1
*
Corresponding author. Tel.: þ91 8242287262; fax: þ91 8242287367.
E-mail address: nbadiadka@yahoo.co.uk (B. Narayana).
0223-5234/$ - see front matter Ó 2006 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2006.09.010

426
K.K. Vijaya Raj et al. / European Journal of Medicinal Chemistry 42 (2007) 425e429
O
activity relationship is not clear from our studies. The higher
activity of 3a may be due to the presence of bioactive salicy-
lamide moiety, which is a moiety present in antihypertensive
drug Labetalol. More studies have to be conducted to get con-
clusive results.
O
NH
NH2
Ar
H C
NH
3
Br
+
S
O
Br
2a-h
1
EtOH
2.2.2. Antiproliferative activity
Three of the newly synthesized compounds such as 3a, 3b
and 3d were screened for their anticancer activity at NIH, Be-
thesda, Maryland, USA under the Drug Discovery Programme
of NCI as per the procedure suggested by Boyd and Paull [18]
in a primary three cell line-one dose antitumor assay against
NCI-H (lung), MCF-7 (breast) and SF-268 (CNS). In the cur-
rent protocol each cell line is inoculated on a preincubated mi-
crotiter plate. Test agents are added at a single concentration
and the culture is incubated for 48 h. End point of determina-
tions is made with sulphorhodamine B, a protein binding dye.
Compounds which reduce the growth of any one of the cell
line to 32% or less (negative numbers indicate cell killing)
are passed on for evaluation in a panel of 60 cell lines over
O
O
NH
S
H C
NH
3
N
Br
a-h
Ar
3
Scheme 1.
1
The H NMR spectrum of compound 3a gave a singlet at
d 3.88 due to three protons of the eOCH group. Two doublets
3
at d 6.93 (J ¼ 9.0 Hz) and d 7.63 (J ¼ 9.0 Hz), two singlets at
d 7.05 and d 7.14 and a doublet of doublet at d 7.9 (J ¼ 9.0 Hz)
are due to aromatic protons. A singlet at d 8.5 is due to eNH
protons and another singlet at d 10.7 is due to eOH proton.
FABMS displayed a peak at m/z 463 (70%) that corresponds
to the molecular ion peak. Another peak at m/z 465 (75%) cor-
responds to M þ 2 ion peak. Elemental analysis also gave sat-
isfactory results for all the compounds. Spectral data of other
compounds are given in Section 4.
a 5-long dose range. In the present screening programme
0
(Table 3) only 3a, 2-bromo-5-methoxy-N -[4-(4-hydroxy-3-
benzamido)-1,3-thiazol-2-yl]benzohydrazide was selected for
0 cell line screening and it showed some antiproliferative ac-
6
tivity on the whole panel of 60 cells derived from seven cancer
cells namely lung, colon, melanoma, renal, ovarian, CNS and
leukemia. Their GI , TGI and LC values were determined.
5
0
50
The 60 cell line screening results show that compound 3a
showed highest antiproliferative activity against leukemia
MOLT-4 cell line with GI50 ¼ 22.6, TGI ¼ 57.0 and
LC50 ꢀ 100. The compound was also active against leukemia
RPMI-8226 [GI ¼ 27.9, TGI ¼ 92.5 and LC ꢀ 100] and
2
2
.2. Biological activities
5
0
50
SR [GI50 ¼ 29.8, TGI ꢀ 100 and LC ꢀ 100] at concentra-
50
.2.1. Analgesic activity (acetic acid induced writhing test)
All the newly synthesized compounds were evaluated for
tions below 30 mM. For all other cell lines, the compound
was ineffective. As observed in analgesic activity, presence
of bioactive salicylamide moiety enhances the antiproliferative
activity also.
their analgesic activity by acetic acid induced writhing test.
Swiss albino mice (25e30 g) of either sex were used for the
experiment. The mice were divided into 10 groups of two
each and was given the drugs in 2% gum acacia orally by ga-
vage feeding as shown in Table 2. Group 1 was given 2% gum
acacia. Group 2 was given diclofenac sodium at a dose of
2.2.3. Antibacterial and antifungal activities
2
.5 mg/kg. Groups 3e10 were administered the test com-
All the newly synthesized compounds 3aeh were evaluated
for their antibacterial and antifungal activities by disc diffu-
sion method and serial plate dilution method [14e16]. Furacin
was used as standard antibacterial drug and Itraconozole was
used as standard antifungal drug. The results are given in
Table 4.
Compound 3b bearing 3,4-dihydroxyphenyl moiety ex-
hibited maximum antibacterial activity. Compounds 3a and
3d bearing salicylamide and 2-chloropyridinyl moieties ex-
hibited maximum antifungal activity among the tested com-
pounds. In our earlier studies [11e13], we have reported the
promising antimicrobial activity of thiazoles bearing salicyla-
mide, 4-dihydroxyphenyl and 2-chloropyridinyl moieties.
Presence of these potent moieties may be the reason for higher
activity of 3a and 3d.
pounds 3aeh, respectively, at a dose of 50 mg/kg suspended
in 10 ml/kg of 2% gum acacia orally by gavage feeding.
Writhing was induced 1 h later by intraperitoneal injection
of 10 ml/kg of 0.6% acetic acid in distilled water [17]. The
number of writhes was counted for 15 min immediately after
the acetic acid injection. The percentage of protection was cal-
culated. The analgesic activity was compared with diclofenac
sodium (2.5 mg/kg) and the results are given in Table 2. The
experiment was conducted after obtaining approval from Insti-
tutional Animal Ethics Committee.
The results show that the analgesic activity of compound 3a
50 mg/kg) is comparable to that of standard drug diclofenac
(
sodium (2.5 mg/kg). Compounds 3e and 3g have also ex-
hibited promising analgesic activity. The exact structuree

K.K. Vijaya Raj et al. / European Journal of Medicinal Chemistry 42 (2007) 425e429
427
Table 1
Physical and analytical data of the compounds 3aeh
a
Yield (%)
ꢁ
Compound no.
Ar-
Mp ( C)
Molecular formula
Nature of product
O
3a
90
228e232
18
C H
15BrN
4
O
4
S
Off white crystals
NH2
OH
3b
90
192e196
17
C H
14BrN
3
O
4
S
Yellow crystals
OH
HO
9
6
8
6
0
4
0
5
200e204
232e236
250e254
162e164
C
C
C
C
20
H
14BrN
3
O
4
S
Yellow microcrystals
Dark yellow crystals
Yellow crystals
3
3
c
O
O
16
H
4 2
12ClBrN O S
d
N
Cl
220 2 3 4
H13Br N O S
Br
3
3
3
e
O
O
17
H
14BrN
3
O
2
S
Off white crystals
f
g
89
228e230
C
17
H
13BrClN
3
O
2
S
Light yellow crystals
Cl
CH3
O
3h
85
228 (dec.)
18
C H
26BrN
3
O
3
S
Cream microcrystals
a
All the yields are on isolated basis. All the compounds gave satisfactory results for elemental analysis. Recrystallisation solvent, methanoleDMF mixture (1:9).

428
K.K. Vijaya Raj et al. / European Journal of Medicinal Chemistry 42 (2007) 425e429
0
Table 2
Analgesic activity (acetic acid induced writhing test) of compounds 3aeh
3.2. Synthesis of 2-bromo-5-methoxy-N -[4-(aryl)-1,3-
thiazol-2-yl]benzohydrazide (3aeh)
Group Drug
Dose
mg/kg)
Average time
taken for onset writhes
writhing (s) for 15 min
No. of
Protection
(%)
(
1
-(2-Bromo-5-methoxybenzoyl) thiosemicarbazide (1)
(
(
1 g, 0.0032 mol) was refluxed with appropriate acyl bromide
0.0032 mol) in 10 ml ethanol for 10 h and kept overnight. The
1
2
2% gum
acacia
Diclofenac
10 ml/kg 246
16
6
e
solid separated on cooling was filtered and the crude products
were recrystallised from 10% methanol in DMF. All the com-
pounds were isolated in 64e90% yields. The characterization
data are given in Table 1.
2.5
692
62.5
sodium
3a
3b
3
4
5
6
7
8
9
1
50
84
432
480
506
454
524
496
336
7
14
10
10
8
56.25
12.5
37.5
37.5
50.0
12.5
43.75
25
50
50
50
50
50
50
50
3c
3d
4
. Spectral and analytical data
3e
3f
3g
14
9
0
4.1. 2-Bromo-5-methoxy-N -[4-(4-hydroxy-3-
benzamido)-1,3-thiazol-2-yl]benzohydrazide (3a)
0
3h
12
N ¼ 2 in each group.
1
H NMR: (CDCl , 300 MHz) d 3.88 (s, 3H, eOCH ),
3
3
d 6.93 (d (J ¼ 2.9, 9.0 Hz), 1H, AreH), d 7.05 (s, 1H,
AreH), d 7.14 (s, 1H, AreH), d 7.63 (d (J ¼ 9.0 Hz), 1H,
AreH), d 7.9 (dd (J ¼ 9.0 Hz), 2H, AreH), d 8.5 (s, 2H, e
3
. Experimental
Melting points were taken in open capillary tubes and are
NHeNHe, exchangeable with D O), d 10.7 (s, 1H, eOH);
uncorrected. The purity of the compounds was confirmed by
thin layer chromatography using Merck silica gel 60 F254
coated aluminium plates. IR spectra were recorded on Shi-
madzu-FTIR spectrometer in KBr (nmax in cm ). H NMR
spectra were recorded in CDCl and in DMSO-d on a Varian
2
þ
FABMS: m/z 463 (M , 70%), 465 (M þ 2, 75%). Anal. Calcd
for C H BrN O S: %C, 46.66; %H, 3.26; %N, 12.09.
18 15
4 4
ꢂ1
1
Found: %C, 46.29; %H, 3.17; %N, 11.89.
3
6
0
4
.2. 2-Bromo-5-methoxy-N -[4-(3,4-dihydroxyphenyl)-
(300 MHz) spectrometer using TMS as an internal standard
1
and C NMR spectra were recorded in CDCl3 and in
3
1,3-thiazol-2-yl]benzohydrazide (3b)
DMSO-d on a Varian (75 MHz) spectrometer. FABMS spec-
6
1
H NMR: (CDCl , 300 MHz) d 3.84 (s, 3H, eOCH ),
3
tra were recorded on a JEOL SX 102/DA-6000 mass spec-
trometer using argon/xenon (6 kV, 10 mA) as the FAB gas.
Compound 2-bromo-5-methoxybenzohydrazide was pre-
pared from methyl-2-bromo-5-methoxybenzoate [19] by treat-
3
d 6.82 (d (J ¼ 8.2 Hz), 1H, AreH), d 6.87 (d (J ¼ 8.2 Hz),
1
1
1
H, AreH), d 6.97 (m, 2H, AreH), d 7.07 (d (J ¼ 8.29 Hz),
H, AreH), d 7.19 (t, 2H, AreH), d 7.62 (d (J ¼ 8.79 Hz),
ꢁ
1
H, AreH), d 11.33 (s, 2H, eNHeNHe, exchangeable with
ing with hydrazine hydrate in methanol; mp 172e174 C. H
NMR (300 MHz): d 3.79 (s, 3H, eOCH ), d 6.84 (dd
þ
D O); FABMS: m/z 440 (M þ 1, 100%), 436 (M , 95%)
2
3
4
4
%
38 (M þ 2, 100%). Anal. Calcd for C H BrN O S: %C,
(
J ¼ 8.8 Hz), 1H, AreH), d 6.95 (d (J ¼ 2.96 Hz), 1H, Are
17 14
3 4
6.80; %H, 3.23; %N, 9.63. Found: %C, 46.59; %H, 3.17;
N, 9.36.
H), d 7.45 (d (J ¼ 8.8 Hz), 1H, AreH), d 9.26 (br s, 1H,
eNH).
0
4
1
.3. 2-Bromo-5-methoxy-N -[4-(2-oxo-2H-chromen-3-yl)-
3.1. Synthesis of 1-(2-bromo-5-methoxybenzoyl)
thiosemicarbazide (1) [20]
,3-thiazol-2-yl]benzohydrazide (3c)
1
H NMR: (CDCl , 300 MHz) d 3.85 (s, 3H, eOCH ),
3
2
-Bromo-5-methoxybenzohydrazide (50 g, 0.204 mol), po-
3
d 6.92 (dd (J ¼ 3.15, 8.81 Hz), 1H, AreH), d 7.12 (d
J ¼ 2.95 Hz), 1H, AreH), d 7.33 (s, 1H, AreH), d 7.35 (s,
H, AreH), d 7.51 (t, 1H, AreH), d 7.54 (s, 1H, AreH),
tassium thiocyanate (25 g, 0.267 mol) and 40 ml of conc. HCl
in 400 ml of water were refluxed for 4 h. A white solid ap-
peared on cooling and then the solid was filtered and dried.
(
1
ꢁ
ꢂ1
d 7.23 (d (J ¼ 7.94 Hz), 1H, AreH), d 7.78 (s, 1H, AreH),
Yield 51.2 g (74.4%); mp 190e192 C. IR (KBr, cm ):
280 (NH), 1670 (CONH), 1360 (C]S).
d 8.61 (s, 1H, AreH), d 10.49 (s, 2H, eNHeNHe, exchange-
able with D O); FABMS: m/z 474 (M þ 2, 100%), 472 (M ,
3
þ
2
Table 3
Antiproliferative activity screening data of the compounds 3a, 3b and 3d
98%). Anal. Calcd for C H BrN O S: %C, 50.86; %H,
3 4
2
0
14
2.99; %N, 8.90. Found: %C, 50.47; %H, 3.24; %N, 8.78.
a
Compound
NCI code
Growth percentage
0
4
.4. 2-Bromo-5-methoxy-N -[4-(4-chlorophenyl)-1,3-
NCI-H
MCF-7
SF-268
thiazol-2-yl]benzohydrazide (3g)
3
3
3
a
b
d
NSC 736958
NSC 736960
NSC 736959
17
101
95
19
86
87
55
111
111
1
H NMR: (CDCl , 300 MHz) d 3.86 (s, 3H, eOCH ), d 7.0
3
3
(
dd (J ¼ 2.66, 8.88 Hz), 1H, AreH), d 7.25 (t, 1H, AreH),
Fixed concentration (100 mM; standard NCI protocol).
a
Active when growth percentage is <32% for any one of the three line cells.
d 7.55 (s, 1H, AreH), d 7.58 (s, 1H, AreH), d 7.23 (dd

K.K. Vijaya Raj et al. / European Journal of Medicinal Chemistry 42 (2007) 425e429
429
Table 4
Antibacterial and antifungal activities of the compounds 3aeh (MIC values in mg/ml)
Compound Antibacterial activity
Antifungal activity
Escherichia
coli
Klebsiella
pneumoniae
Pseudomonas
aeruginosa
Staphylococcus
aureus
Penicillium
marneffei
Aspergillus
flavus
Aspergillus
fumigatus
Trichophyton
mentagrophytes
3
3
3
3
3
3
3
3
a
b
c
d
e
f
e
12.5
12.5
e
e
12.5
50
50
e
12.5
e
60
12.5
e
12.5
50
12.5
100
100
12.5
12.5
e
50
50
e
6.25
e
12.5
12.5
12.5
100
e
100
12.5
10
50
e
e
50
e
e
e
50
e
e
e
e
e
e
e
e
50
e
e
e
50
g
h
50
50
6.25
e
50
e
e
e
e
100
e
Furacin
Itraconozole
12.5
e
12.5
e
12.5
e
e
<16
e
<16
e
<16
<16
(
J ¼ 9.0 Hz), 4H, AreH), d 8.31 (s, 2H, eNHeNHe, ex-
[3] Q. Zhang, A. Haemers, D. VadenBerghe, S.R. Pattyn, W. Bolaert, J. Het-
erocycl. Chem. 28 (1991) 673.
changeable with D O); FABMS: m/z 440 (M þ 1, 100%),
2
þ
[4] P.K. Sharma, S.N. Sownhney, A. Gupta, G.B. Singh, S. Bani, Indian J.
Chem., Sect. B 37 (1998) 371.
4
C H BrClN O S: %C, 46.54; %H, 2.99; %N, 9.58. Found:
39 (M , 60%), 438 (M ꢂ 1, 75%). Anal. Calcd for
1
7
13
3
2
[5] B.S. Holla, K.V. Malini, B.S. Rao, B.K. Sarojini, Eur. J. Med. Chem. 38
(2003) 313.
%
C, 46.32; %H, 2.86; %N, 9.36.
. Conclusion
Eight novel 2-bromo-5-methoxy-N -[4-(aryl)-1,3-thiazol-2-
[
6] Lock, Pharm. Ind. 14 (1912) 400.
[7] J.S. Proudfoot, U.R. Patel, S.R. Kapadia, K.D. Hargrave, J. Med. Chem.
8 (1995) 1406.
5
3
0
[8] B. Plouvier, R. Houssin, N. Helbecque, P. Colson, C. Houssier,
J.P. Henichart, C. Bailly, Anticancer Drugs 10 (1995) 155.
yl]benzohydrazide derivatives were prepared and screened for
analgesic, antifungal, antibacterial and anticancer activities.
Compound 3a exhibited promising analgesic activity. Com-
pound 3b exhibited maximum antibacterial activity and com-
pounds 3a and 3d exhibited maximum antifungal activity
among the tested compounds. Compound 3a further displayed
some antiproliferative activity and the presence of salicylamide
group may be contributing to its enhanced biological activity.
[
9] R. Bai, D.G. Covell, G.F. Taylor, J.A. Kepler, T.D. Copeland,
N.Y. Nguyen, G.R. Pettit, E. Hamel, J. Biol. Chem. 279 (2004) 30731.
[10] E. Brantley, V. Patel, S.F. Stinson, V. Trapani, C.D. Hose, H.P. Ciolino,
G.C. Yeh, J.S. Gutkind, E.A. Sausville, A.I. Loaiza-Perez, Anticancer
Drugs 16 (2005) 137.
[
[
[
[
11] B. Narayana, K.K. Vijaya Raj, B.V. Ashalatha, N. Suchetha Kumari,
B.K. Sarojini, Eur. J. Med. Chem. 39 (2004) 867.
12] B. Narayana, B.V. Ashalatha, K.K. Vijaya Raj, N. Suchetha Kumari,
Phosphorus Sulphur Silicon 181 (2006) 1381.
13] B. Narayana, K.K. Vijaya Raj, B.V. Ashalatha, N. Suchetha Kumari, In-
dian J. Chem., Sect. B 45 (7) (2006) 1704.
Acknowledgements
14] R. Cruickshank, J.P. Duguid, B.P. Marmion, R.H.A. Swain, Medical
Microbiology, twelfth ed., vol. II, Churchill Livingstone, London, 1975,
p. 196.
Authors are thankful to The Head, SAIF, CDRI, Lucknow
and The Director, SAIF, Punjab University for spectral analysis.
Authors are also thankful to Dr. V.L. Narayanan, National Insti-
tute of Health (NIH), Bethesda, USA for arranging the antipro-
liferative activity screening studies reported in this paper.
[15] A.H. Collins, Microbiological Methods, second ed. Butterworth, London,
976.
1
[
16] B.A. Arthington-Skaggs, M. Motley, D.W. Warnock, C.J. Morrison, J.
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[
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tal Pharmacology, second ed., Scientific book agency, Kolkatta, 1984.
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