Synthesis and antimicrobial activities of some 3-arylamino-5-[2-(substituted 1-imidazolyl)ethyl]-1,2,4-triazole derivatives

Article abstract of DOI:10.1016/S0223-5234(00)01178-8

In this study, some 3-arylamino-5-[2-(substituted imidazol-1-yl or benzimidazol-1-yl)ethyl]-1,2,4-triazole derivatives were synthesised by reacting 3-(substituted imidazol-1-yl)propionyl hydrazides, with S-methyl-N'-arylisothiouronium iodide salts. Their structures were elucidated by IR, ¹H-NMR and mass spectroscopic data and elemental analyses results. Antimicrobial activities of the compounds were observed against Staphylococcus aureus NRRL B-767, Micrococcus luteus NRRL B-4375, Escherichia coli B, Pseudomonas aeroginosa NRRL B-23 and the fungi Candida albicans and Candida glabrata by using the tube dilution technique. Remarkable activity was obtained. (C) 2000 Editions scientifiques et medicales Elsevier SAS.

Full text of DOI:10.1016/S0223-5234(00)01178-8

Eur. J. Med. Chem. 35 (2000) 1037–1040
´
© 2000 Editions scientifiques et me´dicales Elsevier SAS. All rights reserved
PII: S0223-5234(00)01178-8/FLA
Laboratory Note
Synthesis and antimicrobial activities of some 3-arylamino-5-[2-(substituted
1-imidazolyl)ethyl]-1,2,4-triazole derivatives
S¸eref Demirayaka, Kadriye Benklia*, Kıymet Gu¨venb
aDepartment of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Anadolu, 26470 Eskis¸ehir, Turkey
bDepartment of Microbiology, Faculty of Science, University of Anadolu, 26470 Eskis¸ehir, Turkey
Received 17 November 1999; revised 6 June 2000; accepted 8 June 2000
Abstract – In this study, some 3-arylamino-5-[2-(substituted imidazol-1-yl or benzimidazol-1-yl)ethyl]-1,2,4-triazole derivatives were
synthesised by reacting 3-(substituted imidazol-1-yl)propionyl hydrazides, with S-methyl-N%-arylisothiouronium iodide salts. Their
1
structures were elucidated by IR, H-NMR and mass spectroscopic data and elemental analyses results. Antimicrobial activities of
the compounds were observed against Staphylococcus aureus NRRL B-767, Micrococcus luteus NRRL B-4375, Escherichia coli B,
Pseudomonas aeroginosa NRRL B-23 and the fungi Candida albicans and Candida glabrata by using the tube dilution technique.
´
Remarkable activity was obtained. © 2000 Editions scientifiques et me´dicales Elsevier SAS
3-amino[1,2,4]triazole / benzimidazol / imidazol / antimicrobial activity
1. Introduction
imidazol-1-yl)propionyl hydrazides were reacted by
heating in pyridine. Pyridine behaves both as a sol-
vent and a base in this reaction. The structures of the
compounds were elucidated by spectral data and ele-
mental analyses. In the IR spectra, the bands due to
NꢀH group, which is present in all studied com-
Triazole moiety may be considered as a bioisostere
of imidazole, which is a part of the azole group of
antifungal drugs (i.e. fluconazole). In this study tri-
azole has been used instead of imidazole [1–3]. As an
extension of our previous work on 3-arylamino-5-
aryloxymethyl-1,2,4-triazole derivatives which showed
appreciable antibacterial and antifungal activities [4],
some new triazole derivatives were synthesised using
substituted nitroimidazolyl-ethyl and benzimidazolyl-
ethyl residues instead of aryloxymethyl groups. An-
tibacterial and antifungal activities of the compounds
were investigated.
pounds, were observed at about 3260–3230 cm−1
.
The bands at about 1050 cm−1 were characteristic for
1
the triazole derivatives [5]. In H-NMR spectra, the
peaks of ethylene protons were observed at about
3.40 ppm as broad singlets and at 4.40 ppm as
triplets. The methylene protons were observed as
broad singlets instead of triplets probably due to the
effect of DMSO used as a solvent [6]. Aromatic
protons were observed at about 6.70–7.60 ppm as
doublets, triplets or multiplets depending on substitu-
tion. The peaks of NꢀH protons of arylamino and
triazole residue were obtained as unequal size dou-
blets, probably due to the tautomeric form of the
compounds. The integral values of these doublets
correspond to one proton for NꢀH groups. In MS
spectra, molecular ion peaks or M+1 peaks were
obtained from EI-MS or ES-MS and FAB-MS spec-
tra, respectively [6] (scheme 1).
2. Chemistry
To obtain 3-aryl-5-[2-(substituted imidazol-1-yl
or benzimidazol-1-yl)-ethyl]-1,2,4-triazole derivatives
IVa–c, Va,b, VIa–c, S-methyl-N%-arylisothiouronium
iodide salts and 3-(substituted imidazol-1-yl or benz-
* Correspondence and reprints:
E-mail address: kbenkli@anadolu.edu.tr (K. Benkli).

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S¸. Demirayak et al. / European Journal of Medicinal Chemistry 35 (2000) 1037–1040
Scheme 1.
3. Results and discussion
results showed that the most sensitive micro-organism
to the control antibiotic, Chloramphenicol Succinate,
is S. aureus and to the control antifungal, Ketocona-
zol, the most sensitive organism is C. glabrata. MIC
values of these standards were lower than expected.
This situation may be attributed to the resistance
gained by the bacteria strains by time. In consider-
ation of the results, we may conclude that some of the
tested products have noticeable antibacterial and anti-
fungal activities. Some of the compounds which pos-
sess lower MIC values (for example, 31.25 mg/mL for
VIb against S. aureus) may be considered as highly
potential antibacterial. Most of the compounds have
62.5 or 125 mg/mL MIC values against these micro-
organisms. Unfortunately, no correlation between the
substituents and biological activities of the com-
pounds was noticeable. Compounds IVa and VIb
showed higher antimicrobial activity than the other
compounds against E. coli, M. lutea and S. aureus.
These better activities, observed for IVa and VIb,
could be interpreted as a consequence of the presence
of a nitroimidazole moiety in their structure. It seems
that, compounds IVa, Vb and VIb have higher anti E.
coli B activities and the compounds IVa and Vb have
higher anti M. luteus activities than Chloramphenicol
Succinate. However, compounds IVa, Va and VIb
have lower anti S. aureus activities than Chloram-
phenicol Succinate. No difference was observed be-
tween the anti C. albicans activities of Ketoconazol
In one of our recent works [4], we found out that
some of the 3-arylamino-5-aryloxymethyl-1,2,4-tria-
zole derivatives were highly effective against aerobic
bacteria. We performed a pharmaco modulation on
these compounds, replacing the 5-aryloxymethyl
group by a (2-substituted-1-imidazolyl)ethyl group.
The compounds, which were synthesised, exhibited
noticeable antibacterial and antifungal activities, as
expected (table I). The in vitro antimicrobial activity
Table I. Antibacterial activity expressed as MIC values in
mg/mLa.
Comp.
E.c.
M.l.
P.a.
S.a.
C.a. C.g.
IVa
IVb
IVc
Va
Vb
VIa
VIb
VIc
A
125
250
250
250
125
250
125
250
250
250
62.5
125
125
250
125
125
125
250
250
125
125
62.5
125
125
62.5
250
250
31.25
125
7.81
7.81
500
500
500
500
500
500
500
500
500
500
125
125
125
125
125
125
125
125
125
125
125
125
250
62.5
125
125
125
62.5
250
B
a A: Ketoconazol, B: Chloramphenicol succinate, E.c.: E. coli
B, M.l.: M. luteus NRRL B-4375, P.a.: P. aeroginosa NRRL
B-23, S.a.: S. aureus NRRL B-767, C.a.: C. albicans, C.g.: C.
glabrata.

S¸. Demirayak et al. / European Journal of Medicinal Chemistry 35 (2000) 1037–1040
1039
and the compounds tested. C. glabrata was more
sensitive to both Ketoconazol and the compounds
tested than C. albicans, and all the compounds gave
the same MIC values for C. glabrata. Hence, the
tested compounds may be regarded as highly active
antifungal substances against C. glabrata and less
active against C. albicans.
poured into crushed ice. The precipitate was collected by
filtration and the raw product was recrystallised from
ethanol.
4.1.2.1. 3-Phenylamino-5-[2-(4-nitroimidazol-1-yl)-
ethyl]1,2,4-triazole IVa
Yield: 52%; m.p.: 192 °C. IR (KBr) nmax (cm−1): 3252
(NꢀH), 1605–1547 (CꢁN, CꢁC), 1495, 1309 (NꢀO), 1056
1
(1,2,4 triazole). H-NMR s (ppm): 3.44 (2H, bs), 4.45
4. Experimental protocols
(2H, t, J=6.71 Hz), 6.7–6.85 (1H, m), 7.15 (2H, t,
J=7.58 Hz), 7.43 (2H, d, J=7.75 Hz), 7.65 (1H, s),
8.20 (1H, s), 12.25, 12.87 (1H, bs). MS ES (M+1) m/z:
300.3; EI: 299.4 (M), 186.4, 118.3, 104.3, 77.3 (100%).
Anal. Calcd. for C13H13N7O2·1/2H2O: C, 50.64; H, 4.57;
N, 31.80. Found: C, 50.67; H, 4.51; N, 31.46.
4.1. Chemistry
Melting points were determined using a Gallenkamp
apparatus and are uncorrected. Spectroscopic data were
recorded on the following instruments: IR: Shimadzu
1
435 IR spectrophotometer; H-NMR: DPX 400 NMR
4.1.2.2. 3-Phenylamino-5-[2-(2-methyl-
spectrometer, Jeol JNM-EX 90A FT NMR spectrome-
ter; MS: VG Platform mass spectrometer. Microanaly-
ses: Leco CHNS elemental analyses apparatus. C, H, N
values were within 90.4% of the theoretical values.
Methyl 3-substituted propionate derivatives (IIa–c) [7,
8] and S-methylisothiouronium salts [9] were prepared
using previously reported methods.
4-nitroimidazol-1-yl)-ethyl]1,2,4-triazole IVb
Yield: 54%; m.p.: 238 °C. IR (KBr) nmax (cm−1):
3260 (NꢀH), 1607–1550 (CꢁN, CꢁC), 1481, 1327 (NꢀO),
1
1062 (1,2,4-triazole). H-NMR s (ppm): 2.29 (3H, s),
3.15 (2H, bs), 4.35 (2H, t, J=6.45 Hz), 6.80 (1H, t,
J=6.85 Hz), 7.20 (2H, t, J=7.25 Hz), 7.49 (2H, d,
J=8.04 Hz), 8.35 (1H, s), 9.1 (1H, s), 12.9 (1H, s). MS
FAB: 314 (M+1). Anal. Calcd. for C14H15N7O2: C,
53.67; H, 4.83; N, 31.29. Found: C, 53.59; H, 4.75; N,
30.75.
4.1.1. General procedure for compounds III
A mixture of suitable II (50 mmol) and hydrazine
hydrate (100 mmol) in methanol (50 mL) was refluxed
for 3 h. The mixture was allowed to cool to crystallise.
The title compounds crystallised by cooling of the reac-
tion mixture.
4.1.2.3. 3-Phenylamino-5-[2-(benzimidazol-1-yl)-
ethyl]1,2,4-triazole IVc
Yield: 73%; m.p.: 201 °C. IR (KBr) nmax (cm−1): 3239
(NꢀH), 1618–1553 (CꢁN, CꢁC), 1496, 1291 (NꢀO), 1041
4.1.1.1. 3-(4-Nitroimidazol-1-yl)-propionylhydrazide IIIa
Yield: 76%; m.p.: 230–234 °C. Anal. Calcd. for
C6H9N5O3: C, 36.18; H, 4.52; N, 35.17. Found: C,
36.22; H, 4.51; N, 35.20.
1
(1,2,4-triazole). H-NMR s (ppm): 3.46 (2H, bs), 4.63
(2H, t, J=6.71 Hz), 6.70–6.85 (1H, m), 7.18–7.27 (4H,
m), 7.46 (2H, d, J=8.13 Hz), 7.58–7.65 (2H, m),
8.12 (1H, s), 9.2 (1H, bs), 12.9 (1H, bs). MS ES (M+1)
m/z: 305.2 (M+1); EI: 305.5 (M+1), 304.5 (M), 186,
172, 131 (100%). Anal. Calcd. for C17H16N6·1/2H2O: C,
65.15; H, 5.47; N, 26.82. Found: C, 65.92; H, 5.83; N,
26.81.
4.1.1.2. 3-(2-methyl-4-nitroimidazol-1-yl)-
propionylhydrazide IIIb
Yield: 62%; m.p.: 146–149 °C. Anal. Calcd. for
C7H11N5O3: C, 39.44; H, 5.16; N, 32.86. Found: C,
39.47; H, 5.18; N, 32.88.
4.1.2.4. 3-(4-Methyl)phenylamino-5-[2-(4-nitroimidazol-
1-yl)-ethyl]1,2,4-triazole Va
4.1.1.3. 3-(benzimidazol-1-yl)-propionylhydrazide IIIc
Yield: 66%; m.p.: 264–266 °C. Anal. Calcd. for
C10H122N4O: C, 58.82; H, 5.88; N, 27.45. Found: C,
58.87; H, 5.85; N, 27.46.
Yield: 48%; m.p.: 186 °C. IR (KBr) nmax (cm−1): 3230
(NꢀH), 1625–1550 (CꢁN, CꢁC), 1495, 1290 (NꢀO), 1040
1
(1,2,4 triazole). H-NMR s (ppm): 2.18 (3H, s), 3.23
(2H, bs), 4.34 (2H, t, J=6.86 Hz), 6.95 (2H, d, J=8.50
Hz), 7.42 (2H, d, J=8.75 Hz), 8.21 (1H, s), 9.20 (1H,
bs), 12.9 (1H, bs). MS FAB: 314 (M+1). Anal.
Calcd. for C14H15N7O2: C, 53.67; H, 4.83; N, 31.29.
Found: C, 53.80; H, 4.70; N, 30.95.
4.1.2. General procedure for compounds IV–VI
A mixture of the suitable III (10 mmol) and S-methyl-
N%-arylisothiouronium iodide salt (10 mmol) in pyridine
(10 mL) was refluxed for 6 h. The cooled mixture was

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S¸. Demirayak et al. / European Journal of Medicinal Chemistry 35 (2000) 1037–1040
4.1.2.5. 3-(4-Methyl)phenylamino-5-[2-(2-methyl
4-nitroimidazol-1-yl)-ethyl]1,2,4-triazole Vb
reus NRRL B-767 and Micrococcus luteus NRRL B-
4375), two Gram-negative bacteria (Escherichia coli B
and Pseudomonas aeroginosa NRRL B-23) and the fungi
(Candida albicans and Candida glabrata) were expressed
as the minimum inhibitory concentration (MIC) values.
The MIC values were determined by the tube dilution
technique [10–12]. MIC values of the synthesised com-
pounds and the control drugs, Ketoconazol and Chlo-
ramphenicol Succinate, were compared. The stock
solutions of the compounds were prepared in DMSO.
The standard bacteria strains were obtained from the
U.S. Department of Agricultural Research Service
(Midwest Area), Northern Regional Research Center
(1815 North University Street, Peoria, IL 61604 USA),
and the University of East Angelia (School of Biological
Sciences, UK). Candida albicans and Candida glabrata
strains were isolated from patients in Osmangazi Uni-
versity Hospital in Turkey. The MIC values, in mg/mL,
are given in table I.
Yield: 55%; m.p.: 228 °C. IR (KBr) nmax (cm−1): 3233
(NꢀH), 1628–1557 (CꢁN, CꢁC), 1495, 1294 (NꢀO), 1045
1
(1,2,4 triazole). H-NMR s (ppm): 2.22 (3H, s), 2.32
(3H, s), 3.31 (2H, bs), 4.44 (2H, t, J=6.35 Hz), 7.01
(2H, d, J=8.69 Hz), 7.36 (2H, d, J=8.86 Hz), 8.41
(1H, s), 8.89 (1H, bs), 12.69 (1H, bs). MS FAB: 328
(M+1). Anal. Calcd. for C15H17N7O2: C, 54.99; H,
5.19; N, 29.94. Found: C, 54.96; H, 5.24; N, 30.11.
4.1.2.6. 3-(4-Chloro)phenylamino-5-[2-(4-
nitroimidazol-1-yl)-ethyl]1,2,4-triazole VIa
Yield: 50%; m.p.: 300 °C. IR (KBr) nmax (cm−1): 3250
(NꢀH), 1615–1549 (CꢁN, CꢁC), 1498, 1312 (NꢀO), 1043
1
(1,2,4 triazole). H-NMR s (ppm): 3.33 (2H, bs), 4.44
(2H, t, J=6.63 Hz), 7.24 (2H, t, J=6.25 Hz), 7.49 (2H,
d, J=8.65 Hz), 7.81 (1H, s), 8.12 (1H, s), 8.41, 8.45
(1H, bs), 12.48, 13.41 (1H, bs). MS FAB: 344 (M+1).
Anal. Calcd. for C13H12ClN7O2·1/2H2O: C, 45.55; H,
3.82; N, 28.61. Found: C, 45.25; H, 3.78; N, 29.01.
References
4.1.2.7. 3-(4-Chloro)phenylamino-5-[2-(2-methyl
4-nitroimidazol-1-yl)-ethyl]1,2,4-triazole VIb
[1] Ram V.J., Pandey H.N., Chem. Pharm. Bull. 22 (1974) 2778–
2783.
Yield: 58%; m.p.: 242 °C. IR (KBr) nmax (cm−1): 3264
(NꢀH), 1613–1542 (CꢁN, CꢁC), 1468, 1337 (NꢀO), 1067
(1,2,4-triazole), 1H-NMR s (ppm): 2.28 (3H, s), 3.44
(2H, bs), 4.34 (2H, t, J=6.54 Hz), 7.14 (2H, d, J=8.91
Hz), 7.49 (2H, d, J=8.68 Hz), 8.22 (1H, s), 9.06, 9.35
(1H, bs), 12.25, 12.50 (1H, bs). MS FAB: 348 (M+1).
Anal. Calcd. for C14H14ClN7O2: C, 48.35; H, 4.05; N,
28.19. Found: C, 47.97; H, 3.85; N, 28.55.
[2] Wolf M.E., Burger’s Medicinal Chemistry, Part II, 4th Edition,
John Wiley and Sons, New York, 1979.
[3] Foye W.O., Lemke T.L., Williams D.A., Principles of Medici-
nal Chemistry, 4th Edition, Williams and Wilkins, Baltimore,
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[4] Demirayak S., Benkli K., Gu¨ven K., Pharm. Acta Helv. 72
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[5] Jennings A.L., Boggs J.E., J. Org. Chem. 29 (1964) 2065–2066.
[6] Silverstein R.M., Bassler G.C., Morrill T.C., Spectrometric
Identification of Organic Compounds, John Wiley and Sons,
New York, 1991.
4.1.2.8. 3-(4-Chloro)phenylamino-5-[2-(benzimidazol-
1-yl)-ethyl]1,2,4-triazole VIc
[7] Bhujanga Rao A.K.S., Gundu Rao C., Singh B.B., J. Org.
Chem. 55 (1990) 3702–3704.
Yield: 68%; m.p.: 194 °C. IR (KBr) nmax (cm−1): 3241
(NꢀH), 1619–1555 (CꢁN, CꢁC), 1497, 1293 (NꢀO), 1045
[8] Efros L.S., Porai-Koshits B.A., Zh. Obshch. Khim. 23 (1953)
697–705 C.A.: 48 7603h.
1
(1,2,4-triazole). H-NMR s (ppm): 3.20 (2H, bs), 4.64
[9] Rasmussen, C.R., Villani, F.J., Raynolds B.E., et al., Synthesis
(1988) 460–466.
(2H, t, J=6.85 Hz), 7.18–7.27 (4H, m), 7.41 (2H, d,
J=8.84 Hz), 7.59–7.65 (2H, m), 8.13 (1H, s), 9.11 (1H,
bs), 12.87 (1H, bs). MS FAB: 340 (M+1). Anal. Calcd.
for C17H15ClN6: C, 60.26; H, 4.46; N, 24.80. Found: C,
59.88; H, 4.28; N, 24.35.
[10] Finegold S.M., Martin W.J., Scott E.G., Bailey and Scott’s
Diagnostic Microbiology, The C.V. Mosby Company, Saint
Louis, 1978.
[11] McGinnis M.R., Rinaldi M.G., Antifungal drugs: mechanism
of action, drug resistance, susceptibility testing and assays of
activity in biological fluids, in: Lorian V. (Ed.), Antibiotics in
Laboratory Medicine, 3rd Edition, Williams and Wilkins, Lon-
don, 1991, p. 198.
4.2. Microbiology
Antimicrobial activities of the synthesised compounds
against two Gram-positive bacteria (Staphylococcus au-
[12] Rodetsky M., Wheeler R.C., Roe M.H., Todd J.K., J. Clin.
Microbiol. 24 (1986) 600–606.