Synthesis and antimicrobial activity of n-[(α-methyl)benzylidene]-(3-substituted-1,2,4-triazol-5-yl-thio) acetohydrazides

Article abstract of DOI:10.1016/S0014-827X(98)00095-0

In this study 18 new hydrazones have been synthesized by reacting ortho- or para-substituted acetophenones with (3-substituted-1,2,4-triazol-5-yl-thio)acetohydrazide in ethanol. The prepared compounds were tested for antimicrobial activity. The prepared compounds exhibited only poor activity against Gram (+) and Gram (-) bacteria with the minimal inhibitory concentration (MIC) ≥ 400 μg/ml. Moderate activity was observed against Candida species with MIC in the range 100-400 μg/ml.

Full text of DOI:10.1016/S0014-827X(98)00095-0

Il Farmaco 53 (1998) 773–776
Short communication
Synthesis and antimicrobial activity of
N-[(a-methyl)benzylidene]-(3-substituted-1,2,4-triazol-5-yl-thio)
acetohydrazides
Seyhan Ersan a,*, Sultan Nacak a, Rukiye Berkem b
a Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Gazi Uni6ersity, Hipodrom, 06330 Ankara, Turkey
b Ankara Hospital, Department of Microbiology and Clinical Microbiology, Cebeci, Ankara, Turkey
Received 9 July 1998; accepted 16 November 1998
Abstract
In this study 18 new hydrazones have been synthesized by reacting ortho- or para-substituted acetophenones with (3-substi-
tuted-1,2,4-triazol-5-yl-thio)acetohydrazide in ethanol. The prepared compounds were tested for antimicrobial activity. The
prepared compounds exhibited only poor activity against Gram (+) and Gram (−) bacteria with the minimal inhibitory
concentration (MIC)]400 mg/ml. Moderate activity was observed against Candida species with MIC in the range 100–400 mg/ml.
© 1998 Elsevier Science S.A. All rights reserved.
Keywords: Antibacterial agents; Antifungal agents; Substituted-triazole derivatives
1. Introduction
2. Chemistry
Substituted 1,2,4-triazole derivatives have been asso-
ciated with various types of biological effects such as
antiviral, antibacterial, anti-inflammatory and anticon-
vulsant activity [1–6]. The 1,2,4-triazole derivatives
have been reported in the literature to show antifungal
activities [7–9]. In addition to these findings it is known
that some hydrazones have antimicrobial activity [10].
On the basis of these data we have synthesized some
hydrazones of 3 - substituted - 1,2,4 - triazol - 5 - yl - thio-
acetohydrazide (Table 1) by reacting (3-substituted-
1,2,4-triazol-5-yl-thio)acetohydrazide with substituted
acetophenones, and their antimicrobial activities were
investigated.
For the synthesis of the title compounds the reaction
sequences outlined in Scheme 1 were followed, starting
from 3-substituted-5-mercapto-1,2,4-triazole [11]. The
reaction of 3-substituted-5-mercapto-1,2,4-triazole with
ethyl bromoacetate has given ethyl (3-substituted-1,2,4-
triazol-5-yl-thio)acetate. The ester has been converted
to the corresponding hydrazide which has given the title
compounds by the reaction with ortho- and para-substi-
tuted acetophenones.
3. Experimental
3.1. Chemistry
All chemicals were obtained from Aldrich Chemical
Co. (Steinheim, Germany). Melting points were deter-
mined with an Electrothermal melting point apparatus
(Southend, UK) and are uncorrected.
* Corresponding author.
0014-827X/98/$ - see front matter © 1998 Elsevier Science S.A. All rights reserved.
PII: S0014-827X(98)00095-0

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S. Ersan et al. / Il Farmaco 53 (1998) 773–776
Table 1
Physical and chemical data of hydrazones of (3-substituted-1,2,4-triazol-5-yl-thio)acetohydrazides
Comp.
R
R1
M.p. (°C)
Yield (%)
Formula
Analysis
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
H
H
H
H
H
H
CH3
CH3
CH3
CH3
CH3
CH3
C2H5
C2H5
C2H5
C2H5
C2H5
C2H5
4-Cl
136
143
193
195
190
192
168
198
158
98
177
188
116
192
165
148
153
195
63
60
50
47
40
35
50
44
50
65
72
66
45
32
68
56
57
67
C12H12ClN5OS
C12H13N5O2S
C12H12N6O3S
C12H12ClN5OS
C12H13N5O2S
C12H12N6O3S
C13H14ClN5OS
C13H15N5O2S
C13H14N6O3S
C13H14ClN5OS
C13H15N5O2S
C13H14N6O3S
C14H16ClN5OS
C14H17N5O2S
C14H16N5O3S
C14H16ClN5OS
C14H17N5O2S
C14H16N5O3S
C, H, N, S
C, H, N, S
C, H, N, S
C, H, N, S
C, H, N, S
C, H, N, S
C, H, N, S
C, H, N, S
C, H, N, S
C, H, N, S
C, H, N, S
C, H, N, S
C, H, N, S
C, H, N, S
C, H, N, S
C, H, N, S
C, H, N, S
C, H, N, S
4-OH
4-NO2
2-Cl
2-OH
2-NO2
4-Cl
4-OH
4-NO2
2-Cl
2-OH
2-NO2
4-Cl
4-OH
4-NO2
2-Cl
2-OH
2-NO2
IR spectra were recorded on a Perkin–Elmer 1330
spectrometer (Uberlingen, Germany) [KBr, w (cm−1)].
1H NMR spectra were recorded on a Bruker 400 MHz
NMR spectrometer (Rheinstetten, Karlsruhe, Ger-
many) using TMS as internal standard and DMSO-d6.
All chemical shifts were reported as l (ppm) values.
Elemental analyses were performed with Leco-932 (C,
H, N, S elemental analyzer, St. Joseph, USA) at the
Scientific and Technical Research Council of Turkey,
Instrumental Analysis Center (Ankara, Turkey), and
the results were within 90.4% of the calculated values.
3.1.3. Spectral data of the compounds
The IR spectra of hydrazones of (3-substituted-1,2,4-
triazol-5-yl-thio)acetohydrazides showed absorption
bands at 3260 and 3000 cm−1 due to the 1,2,4-triazole
moiety. Moreover CꢀO, amide II and CꢀN– stretching
absorption bands were observed between 1685–1655,
1565–1510 and 1440–1380 cm−1, respectively.
3.1.1. (3-Substituted-1,2,4-triazol-5-yl-thio)-
acetohydrazides
To the solution of ethyl (3-substituted-1,2,4-triazol-5-
yl-thio)acetate [10] in ethanol, an equimolar amount of
hydrazine hydrate was added and the solution was then
stirred. The mixture was heated under reflux for 8 h.
After evaporating ethanol, a solid compound was re-
crystallized from absolute ethanol.
3.1.2. Hydrazones of (3-substituted-1,2,4-triazol-5-
yl-thio)acetohydrazides
(3-Substituted-1,2,4-triazol-5-yl-thio)acetohydrazide
(0.003 mol) was dissolved in 10 ml ethanol and 0.2 ml
acetic acid and 0.004 mol of o- or p-substituted ace-
tophenone was added. The mixture was refluxed for 6
h, then left overnight at room temperature. The solid
material which precipitated was filtered, dried and re-
crystallized from ethanol. Data concerning these com-
pounds are presented in Table 1.
Scheme 1. Synthetic route of N-[(a-methyl)benzylidene]-(3-substi-
tuted-1,2,4-triazol-5-yl-thio)acetohydrazides.

S. Ersan et al. / Il Farmaco 53 (1998) 773–776
775
Table 2
Antifungal activity of hydrazones of (3-substituted-1,2,4-triazol-5-yl-thio)acetohydrazides (MIC in mg/ml)a
Compound
Organisms
C. albicans
24 h
C. parapsilosis
C. krusei
48 h
24 h
48 h
24 h
48 h
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
200
200
100
200
800
200
200
200
100
200
800
200
100
200
100
200
200
200
0.5
200
200
400
200
800
400
200
200
200
200
800
400
400
400
400
400
200
400
200
200
100
200
800
100
200
200
100
100
800
200
100
200
100
100
200
100
0.5
400
400
400
400
800
400
400
400
200
400
800
400
400
400
400
400
400
200
400
200
100
200
400
200
200
200
200
200
800
200
200
200
200
200
200
400
0.5
400
400
200
400
800
200
400
400
400
400
800
400
200
200
400
200
400
400
17
18
Clotrimazole
1.0
1.0
1.0
a MIC, minimal inhibitory concentration.
The absorption bands associated with other func-
tional groups appeared in the expected regions.
In the H NMR spectra of title compounds, there are
3.2.2. Methods
The reference compounds penicillin G, ampicillin,
gentamicin, vancomycin and clotrimazole were dis-
solved in DMSO at 800 mg/ml. Two-fold diluted solu-
tions of the compounds and references were prepared
(800, 400, 200, 100,..., 3.15 mg/ml). Microorganism sus-
pensions at 106 CFU (colony forming units)/ml were
inoculated to the wells. The plates were incubated at
36°C for 24–48 h. The incubation chamber was kept
sufficiently humid. The minimal inhibitory concentra-
tions (MIC) values were determined at the end of the
incubation period.
1
two singlets at about 3.95 and 4.30 ppm (2H) of the
CH2 group of the thioacetyl moiety. This phenomenon
may be attributed to the folding of the side chain on to
the sulfur bridge in solution. In other words these two
singlets might represent two rotamers. In accordance
with our suggestions, –CONH–N signals also appear
as two singlets at 11.44–11.88 ppm. The same feature
of similar compounds has been reported by Gu¨rsoy et
al. [12].
3.2. Pharmacology
4. Results and discussion
3.2.1. Materials
The microdilution susceptibility test in Mueller-Hin-
ton Broth (Oxoid Ltd., Basingstoke, Hampshire, UK)
and Sabouraud Liquid Medium (Difco, Detroit, Michi-
gan, USA) were used for the determination of anti-
microbial activity [13–15]. Test organisms were:
Staphylococcus aureus ATCC 29213 and Enterococcus
faecalis ATCC 29212 as Gram (+) bacteria, Es-
cherichia coli ATCC 25922 and Pseudomonas aerugi-
nosa ATCC 27853 as Gram (−) bacteria, and Candida
albicans ATCC 90028, C. parapsilosis ATCC 90018 and
C. krusei ATCC 6258 as yeast. Antibacterial and anti-
fungal screening were carried out using the same
method.
The antibacterial activity was present in almost all
the prepared compounds, but it was rather poor with
MIC around 400 mg/ml for both Gram (+) and Gram
(−) strains, thus quite far from MIC of reference drugs
(penicillin G, ampicillin, gentamicin, vancomycin) that
were in the range 0.5–8 mg/ml. Compounds 5, 10 and
11 were completely inactive.
Somewhat better results were obtained against yeasts
(Table 2). Apart from compounds 5 and 11 (once more
completely inactive), the tested compounds exhibited
MIC in the range 100–400 mg/ml. The highest activities
were shown by compounds 3, 9, 13 and 15, all carrying
a Cl or NO2 group on the benzylidene moiety.

776
S. Ersan et al. / Il Farmaco 53 (1998) 773–776
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