Synthesis, antibacterial and antifungal activity of 4-substituted-5-aryl-1, 2,4-triazoles

Article abstract of DOI:10.3390/61000815

A few 4-allyl/amino-5-aryl-1,2,4-triazoles were synthesized and tested for antibacterial and antifungal effects against Escherichia coli, Bacillus subtilis, Salmonella enteritidis, Staphylococcus aureus, Aspergillus niger and Candida albicans. 4-Allyl-5-aryl-1,2,4-triazoles were obtained by the oxidative cyclization of the appropriate 1-substituted-4-allylthiosemicarbazides and 4-amino-5-aryl-1,2,4-triazoles were obtained by cyclization of the potassium salts of appropriately substituted dithiocarbazinic acids with hydrazine hydrate. The new synthesized compounds were characterized using IR, ¹H- NMR, ¹³C-NMR and UV spectral data together with elemental analysis.

Full text of DOI:10.3390/61000815

Molecules 2001, 6, 815-824
molecules
ISSN 1420-3049
http://www.mdpi.org
Synthesis, Antibacterial and Antifungal Activity of
4-Substituted-5-Aryl-1,2,4-Triazoles
Katica Colanceska-Ragenovic1, Vesna Dimova1,*, Vlado Kakurinov2, Dora Gabor Molnar3
and Aleksandra Buzarovska1
1
Faculty of Technology and Metallurgy, The “Sv. Kiril & Metodij” University, R. Boskovic 16, 1000
Skopje, Macedonia.
2 Faculty of Agriculture, Department of Microbiology, The “Sv. Kiril & Metodij” University, Bul.
Aleksandar Makedonski, bb, 1000 Skopje, Macedonia.
3 Institute of Chemistry, Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovica 3, 21000
Novi Sad, Yugoslavia.
*Author to whom correspondence should be addressed; e-mail: vdimova@hotmail.com
Received: 8 February 2001; in revised form 24 September 2001 / Accepted: 26 September 2001 /
Published: 30 September 2001
Abstract: A few 4-allyl/amino-5-aryl-1,2,4-triazoles were synthesized and tested for
antibacterial and antifungal effects against Escherichia coli, Bacillus subtilis, Salmonella
enteritidis, Staphylococcus aureus, Aspergillus niger and Candida albicans. 4-Allyl-5-
aryl-1,2,4-triazoles were obtained by the oxidative cyclization of the appropriate 1-
substituted-4-allylthiosemicarbazides and 4-amino-5-aryl-1,2,4-triazoles were obtained
by cyclization of the potassium salts of appropriately substituted dithiocarbazinic acids
with hydrazine hydrate. The new synthesized compounds were characterized using IR,
1H- NMR, 13C-NMR and UV spectral data together with elemental analysis.
Key words: Substituted benzoyl/phenylcetyl-4-allylthiosemicarbazides, 1,2,4-triazoles,
cyclization, inhibition zone.

Molecules 2001, 6
816
Introduction
1,2,4-Triazole and its derivatives represent one of the most biologically active classes of compounds,
possessing a wide spectrum of activities. The 1,2,4-triazole nucleus is associated with diverse
pharmacological activities such as antibacterial, antifungal, hypoglycemic, antihypertensive and
analgesic properties [1-5]. The scientific literature also states that the antiviral [6] and antibacterial [7,8]
activities of thiourea derivatives are due to the presence of the -NH-C(S)-NH- function in the molecule
and the changes in this activity depend on the nature of its substituents. These observations prompted us
to synthesize some new triazoles and to investigate their antibacterial and antifungal activities.
Results and Discussion
The aim of this work was a synthesis of 4-substituted-5-aryl-1,2,4-triazoles (Scheme 1).
Scheme 1
R’OH
Ar-COOH
Ar-COOR’
(1a-f)
(2a-f)
Ar = 2-OH-C6H4-;
4-OH- C6H4-;
R’ = CH3-; C2H5-;
NH2-NH2xH2O
2-OH-5-Cl- C6H3-;
4-C2H5O- C6H4-;
4-OH- C6H4-CH2-;
4-C2H5O- C6H4-CH2-
Ar-CO-NH-NH2
(3a-f)
Route I
CH2=CH-CH2-NCS
Route II
KOH; CS2
Ar-CO-NH-NH-C(S)-S-K+
Ar-CO-NH-NH-C(S)-NH-CH2-CH=CH2
(4a-d)
(4e-h)
1. 2M NaOH;
2. HCl
1. NH2-NH2xH2O;
2. HCl
N
N
N
NH
N
N
N
NH
Ar-
Ar-
Ar-
Ar-
C
C=S
C
C SH
C
C SH
C
C=S
N
N
N
N
CH -CH=CH
NH
2
2
CH -CH=CH
2
NH
2
2
2
(5e-h)
(5a-d)

Molecules 2001, 6
817
In order to achieve this aim it was necessary to first synthesize hydrazides 3a-f of some substituted
benzoic (2-hydroxy-; 4-hydroxy-; 2-hydroxy-5chloro-and 4-ethoxy-) and substituted phenylacetic (4-
hydroxy- and 4-ethoxy-) acids. Hydrazides 3a-f were prepared by reactions of corresponding
methyl/ethyl esters and hydrazine hydrate. The next step was conversion of the derivatives 3 into the
corresponding 4-allyl-5-aryl-1,2,4-triazoles (Route I) and 4-amino-5-aryl-1,2,4-triazoles (Route II).
When 2-hydroxy- (3a); 4-hydroxy- (3b); 2-hydroxy-5-chlorobenzhydrazide (3c) and 4-
ethoxyphenylacetylhydrazide (3e) were refluxed with allylisothiocyanates in ethanolic solution, 1-
substituted-4-allylthiosemicarbazides (4a-d) were obtained. The melting points, yields and elemental
analyses of compounds (4a-d) are given in Table 1.
Table 1: Physical and analytical data of compounds 4a-d and 5a-h
Elemental analysis
Mol. formula
mol.wt
Mp
0C
Yield
%
Ar
calc./found
H
C
N
C11H13N3O2S
(251.311)
C11H13N3O2S
(251.311)
C11H12N3O2ClS
(285.755)
C14H19N3O2S
(293.389)
C11H11N3OS
(233.293)
C11H11N3OS
(233.293)
C11H10N3OClS
(267.738)
C14H17N3OS
(275.374)
C8H8N4OS
208.17
52.57 5.21
52.40 5.25
52.57 5.21
52.51 5.19
45.92 4.59
45.99 5.06
57.31 6.53
57.41 6.49
56.63 4.75
56.03 4.90
56.63 4.75
56.85 4.98
49.35 3.76
49.27 3.55
61.06 6.22
61.12 6.10
46.14 3.89
45.96 4.29
46.14 3.89
46.96 4.09
48.63 4.35
49.14 5.02
52.98 5.61
52.91 5.87
16.72
16.69
16.72
16.75
14.71
14.64
14.32
14.44
18.01
17.95
18.01
18.32
15.69
15.58
15.26
15.31
26.90
26.39
26.90
26.59
25.20
24.84
22.29
21.99
4a
4b
4c
2-OH-C6H4-
4-OH-C6H4-
198-9
194-6
188-90
180-2
203-5
176-8
142 - 4
84.39
84.76
92.53
82
2-OH-5-Cl-C6H3-
4-C2H5O-C6H4-CH2-
2-OH-C6H4-
4d
5a*
5b
5c
89.59
93.54
67.62
4-OH-C6H4-
2-OH-5-Cl-C6H4-
4-C2H5O-C6H4-CH2-
2-OH-C6H4-
125 - 7
202-3
90
5d
71.6
5e**
C8H8N4OS
208.17
C9H10N4OS
222.18
C11H14N4OS
250.22
4-OH-C6H4-
217
81.5
13.87
64.9
5f
5g
5h
4-OH-C6H4-CH2-
4-C2H5O-C6H4-CH2-
203-4
101-3

Molecules 2001, 6
818
The structures of compounds 4a-d were established by their IR, 1H-NMR and 13C-NMR spectra. The
IR absorptions due to the C=O and C=S functions appeared at 1660/1600 and 1280/1240 cm-1,
respectively. The absorption bands associated with other functional groups present all appeared in the
1
expected regions. The H-NMR spectra of compounds 4a-d (in DMSO-d6) exhibited a multiplet in the
aromatic region at 6.83-7.91 ppm corresponding to the Harom protons. Three or four low fields singlets
were observed at the 8.11-11.96 ppm region representing the protons of the OH group and the NH
(thiosemicarbazide moiety), due to strong deshielding effect of the aromatic ring system and the
thiocarbonyl group. The 1H-NMR spectra of 4a-d also exhibited the CH2- and –CH- signals of the allyl
13
group as multiplets and doublets between 4.09 and 5.83 ppm. The C-NMR spectra of 4a-d exhibited
C=S signals at 181.5 – 181 ppm.
When compounds 4a-d were refluxed in 2M NaOH solution for about 4 hours, they produced 4-
allyl-5-aryl-1,2,4-triazoles 5a-d in good yields (Table 1). Oxidative cyclization reactions of
thiosemicarbazides have been previously described [9-11]. Except for 5a, which had been previously
reported in the literature [21], all the compounds 5 reported in the present work are novel, and were all
obtained in the form of high melting solids. The spectral data are in good agreement with the proposed
structures. While 1,2,4-triazoles may exist in thione-thiol tautomeric forms, our investigations showed
that in this case the thione structures dominate in the solid state, as indicated by the IR and NMR data of
compounds 5a-d. Thus, their IR spectra (KBr disks) showed no absorption bands around 2600-2550
cm-1 indicative of the thiol form. The IR absorptions due to the C=S functions in 5a-d appeared at about
1320-1300 cm-1[8,12]. The 1H-NMR spectra of 5a-d (DMSO-d6) exhibited the NH signals (NH function
of the triazoline ring) as a singlet between 12.49 and 13.98 ppm which also supports the proposed thione
structure [13,14]. The signals associated with other functional groups all appeared in the expected
regions, such as CH2- and –CH- signals of the allyl groups as multiplets and doublets between 4.49 and
5.80 ppm. The 13C-NMR spectra of 5a-d exhibited C=S signals at 166.7-167.4 ppm.
When 2-hydroxy- (3a); 4-hydroxybenzhydrazide (3b); 4-hydroxy- (3d) and 4-ethoxy-
phenylacetylhydrazide (3e) were refluxed in ethanol with carbon disulfide and potassium hydroxide, the
corresponding potassium salts of the substituted dithiocarbazinic acids 4e-h were formed. Further, the
potassium salts upon reaction with hydrazine hydrate yielded the corresponding 4-amino-5-aryl-1,2,4-
triazoles 5e-h. Of the 5e-h series, all the compounds prepared were novel, except for 5e [22, 23]. The
melting points, yield and elemental analyses of these compounds are given in Table 1. The structures of
5e-h were established by their IR and UV spectra. Thus, the UV spectra of 5e-f showed two absorption
maxima or shoulders at 252-256 and 288-298 nm. These data indicated that these compounds exist
predominantly in the thione form in ethanolic solution [15,16]. The absorption at 288-298 nm indicated
the presence of a chromophoric C=S group. In addition to the UV data, their IR spectra (KBr disks) also
showed a band in the 1266-1249 cm-1 region due to the C=S function, further supporting the
predominance of the thione form in the solid state and in polar solvents [8,12].
The UV spectral data of compounds 5g-h showed that they exist predominantly in the thiol form in
ethanolic solutions, as no absorption maxima or shoulders are observed in the 288-298 nm region which
would be indicative of the thione form. The fact that the compounds exist in thione-thiol tautomeric
equilibria is supported by the absence of characteristic (SH) absorption bands in the IR spectra. The IR

Molecules 2001, 6
819
spectra of compounds 5e-h showed characteristic absorption bands around 3306-3152cm-1 (OH and NH
stretch); 3103-2955 cm-1 (C-H from Ar-H stretch); 2972-2788 cm-1 (C-H from CH2 stretch);1626-1599
cm-1 (C=C); 1583-1514 cm-1 (C=N) and 1534-1480 cm-1 (N-H).
Biological Testing
A filter paper disc method [14] was employed for the in vitro study of antifungal and antibacterial
effects against Escherichia coli, Bacillus subtilis, Salmonela enteritidis, Staphylococcus aureus,
Aspergillus niger and Candida albicans. The inhibitory effects of compounds 4a-d and 5a-h against
these organisms are given in Table 2.
The screening results indicate that not all compounds exhibited antibacterial and antifungal
activities. It can be noted that compounds with free NH2 groups in the 4 position (5e-h) showed the
greatest inhibitory effect against one or more types of bacteria compared to those with allyl groups in the
same position (5a-d). Compounds 4a, 5a and 5d showed no inhibitory effects against any of the tested
organisms. From the results, we can also see that the rest of compounds showed lower fungicidal effects
compared with their bactericidal effects.
We can also compare the inhibitory effect of the thiosemicarbazides 4a-d with the similar effects of
their cyclised products, the triazoles 5a-d. For example, after oxidative cyclization of 4b and 4c, the
resulting 1,2,4-triazoles 5b and 5c showed the highest inhibitory effects against all the test organisms.
But, this effect completely disappeared upon ring formation in the case of compound 4a. The 4-amino-5-
(4-hydroxyphenyl)-1,2,4-triazole (5f) showed the highest inhibition zone diameter against
Staphylococcus aureus (28 mm), compared with all the test organisms and all the tested compounds.
Table 2: Inhibition zones (mm)
Concentration Escherichia Bacillus Salmonella Staphilococcus Aspergillus Candida
Comp.
[mg/ml]
coli
-
subtilis
enteritidis
aureus
niger
albicans
-
-
-
-
-
-
-
5.5
6
-
-
-
1
5
5.5
6
5.5
5.5
4a
4b
4c
5.5
10
1
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
5
-
-
10
1
6
6
9
5.5
10
10
5
10

Molecules 2001, 6
820
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
1
4d
5a
5b
5c
5d
5e
5f
5
10
1
-
-
-
-
-
-
-
-
-
-
-
-
5
-
-
-
-
10
1
6
6
6
-
-
-
-
5.5
8
5.5
6
9
-
7
8
-
-
5
-
5.5
5.5
5.5
5.5
-
10
1
-
-
6
12
-
-
5
-
5.5
-
10
1
-
-
-
-
-
-
5
-
-
-
-
-
10
1
6
6
6
7
8
10
12
10
12
14
-
8
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
7
5
10
23
12
25
28
6
10
1
6.5
8
10
7
5
8
10
11
6
10
1
10
6
5g
5h
5
7
6
-
12
12
12
16
22
10
1
8
7
-
10
10
10
6
8
5
6
9
10
7
9
- : No inhibition zone

Molecules 2001, 6
821
Experimental
General
The melting points of synthesized compounds were determined on a Büchi 510 melting point
apparatus and are uncorrected. The IR spectra were recorded in the 4000-400 cm-1 range using KBr
1
13
disks on a Perkin-Elmer 297 Spectrophotometer. The H- and C-NMR spectra were recorded on a
Bruker AC 250E spectrometer in DMSO-d6 with TMS as an internal standard. UV spectra were recorded
on a Varian Cary 219 spectrophotometer.
Synthesis of derivatives
Synthesis of methyl/ethyl esters of substituted benzoic/phenylacetic acids (2a-f)
These were synthesized by esterification of 2-hydroxy-; 4-hydroxy-; 2-hydroxy-5-chloro-and 4-
ethoxybenzoic and 4-hydroxy- and 4-ethoxyphenylacetic acids, respectively, using excess
methanol/ethanol in the presence of H2SO4 [24].
Synthesis of hydrazides of substituted benzoic and phenylacetic acids (3a-f)
These were prepared by reaction of the corresponding methyl/ethyl esters 2a-f with hydrazine
hydrate following literature methods [17,18,19].
Synthesis of 1-substituted benzoyl/phenacetyl-4-allylthiosemicarbazides (4a-d)
A mixture of the corresponding compound 3a-f (0,01 mol) and allylisothiocyanate (0.01 mol) in
ethanol (120 mL) was heated under reflux for 2-3 hours. The excess of ethanol was distilled off under
reduced pressure. The white precipitate thus formed was washed with ethanol and recrystallised from
ethanol.
4a: IR (cm-1): 1630 (C=O), 1260 (C=S); 1H-NMR: 6.89-6.96 (2H, d, arom), 7.45 (1H, dd, J=1.5 and 7.0
Hz, arom), 7.86 (1H, dd, J=1.2 and 7.9 Hz, arom), 8.38, 9.53 and 10.60-11.96 (4H, s, OH and 3NH),
4.10 (2H, m, CH2=CH-CH2-), 5.05 and 5.14 (2H, dd, J=1.5 and 10.1 Hz, CH2=CH-CH2-), 5.83 (1H, m,
CH2=CH-CH2-); 13C-NMR: 46.0 (CH2), 115.3, 117.2, 118.8, 128.6, 134.1, 134.9, 150.7 (Cq, C-O),
159.5 (C=O), 181.6 (C=S).
4b: IR (cm-1): 1600 (C=O), 1240 (C=S); 1H-NMR: 6.83 (2H, d, J=8.7 Hz, arom), 7.81 (2H, d, J=8.7 Hz,
arom), 8.24, 9.30 and 10.03-10.13 (4H, OH and 3NH), 4.11 (2H, m, CH2=CH-CH2-), 5.03 and 5.13 (2H,
dd, J=1.6 and 10.3 Hz, CH2=CH-CH2-), 5.82 (1H, m, CH2=CH-CH2); 13C-NMR: 46.0 (CH2), 115.0 (2 x
C), 115.3, 123.3, 130.1 (2 x C), 135.2, 160.2, 160.9, 165.9.

Molecules 2001, 6
822
4c: IR (cm-1): 1650 (C=O), 1280 (C=S); 1H-NMR: 6.96 (1H, d, J=8.8 Hz, arom), 7.49 (1H, dd, J=2.6 and
8.8 Hz, arom), 7.91 (1H, d, J=2.6 Hz, arom), 8.36, 9.55, 10.65 and 11.89 (4H, s, OH and 3NH), 4.09
(2H, m, CH2=CH-CH2-), 5.06 and 5.10 (1H, dd, J=1.8 and 10.3 Hz, CH2=CH-CH2-), 5.83 (1H, m,
13
CH2=CH-CH2-); C-NMR 46.0 (CH2), 115.4, 116.5, 119.1, 126.8, 128.1, 133.6, 138.4, 158.0 (qC, C-
O), 181.5 (C=S).
4d: IR (cm-1): 1660 (C=O), 1260 (C=S); 1H-NMR 6.84 (2H, d, J=8.5 Hz, arom), 7.18 (2H, d, J=8.5 Hz,
arom), 8.11, 9.27 and 9.92 (3H, s, NH), 4.10 (2H, m, CH2=CH-CH2-), 5.05 and 5.10 (1H, dd, J=1.5 and
10.3 Hz, CH2=CH-CH2-), 5.82 (1H, m, CH2=CH-CH2), 1.31 (3H, t, J=7.0 Hz, -OCH2CH3), 3.98 (2H, q,
J=7.0 Hz, -OCH2CH3), 3.39 (2H, s, -CH2-); 13C-NMR: 14.7 (CH3), 39.4 (CH2), 45.8 (CH2), 62.9 (CH2),
114.1 (2 x C), 115.2, 127.2, 130.3 (2 x C), 134.9, 157.2, 170.2 (C=O), 181.8 (C=S).
Synthesis of 4-allyl-5-aryl-1,2,4-triazoles (5a-d)
1-Substituted benzoyl/phenylacetyl-4-allylthiosemicarbazides (4a-d) (0,005 mol) were dissolved in
2M NaOH (15 mL) and the reaction mixture refluxed for 4 hours. After cooling, the solution was
dissolved in ice-cold water and acidified with hydrochloric acid to pH 5-6. The solid was filtered,
washed with cold water (to neutral pH), dried and recrystallised from the appropriate solvent.
1
5a: IR (cm-1): 1485 (s, C=N), 1300 (s, C=S); H-NMR: 6.90 (1H, td, J=7.3 Hz, arom), 6.99 (1H, dd,
J=8.2 Hz, arom), 7.26 (1H, dd, J=1.8 and 8.2 Hz, arom), 7.38 (1H, td, J=1.8 and 7.3 Hz, arom), 10.38
(1H, s, OH), 13.91 (1H, s, NH), 4.54 (2H, d, J=5.2 Hz, CH2=CH-CH2-), 4.70 (1H, dd, J=1.5 and 17.1
Hz, CH2=CH-CH2-), 4.95 (1H, dd, J=1.5 and 10.1 Hz, CH2=CH-CH2-), 5.65 (1H, m, CH2=CH-CH2-);
13C-NMR: 45.6 (CH2), 113.3, 116.0, 117.1, 119.3, 131.5, 132.5, 150.1, 155.7, 166.7 (C=S),
5b: IR (cm-1): 1500 (s, C=N), 1320 (s, C=S); 1H-NMR 6.87 (2H, d, J=8.5 Hz, arom), 7.44 (2H, d, J=8.5
Hz, arom), 10.13 (1H, s, OH), 13.81 (1H, s, NH), 4.62 (2H, d, J=3.4 Hz, CH2=CH-CH2-), 4.82 (1H, d,
J=17.1 Hz, CH2=CH-CH2-), 5.09 (1H, d, J=10.4, CH2=CH-CH2-), 5.80 (1H, m, CH2=CH-CH2-);
13C-NMR 46.2 (CH2), 116.0 (2 x C), 116.7, 117.4, 130.2 (2 x C), 132.1, 151.9, 160.7 (Cq, C-O), 167.4
(C=S).
5c: IR (cm-1): 1500 (s, C=N), 1320 (s, C=S); 1H-NMR 7.01 (1H, d, J=8.9 Hz, arom), 7.36 (1H, d, J=2.5
Hz, arom), 7.43 (1H, dd, J=2.5 and 8.6 Hz, arom), 10.72 (1H, s, OH), 13.98 (1H, s, NH), 4.55 (2H, d,
J=5.2 Hz, CH2=CH-CH2-), 4.75 (1H, dd, J= 1.2 and 17.1 Hz, CH2=CH-CH2), 4.98 (1H, dd, J=1.2 and
13
10.38 Hz, CH2=CH-CH2-), 5.67 (1H, m, CH2=CH-CH2-); C-NMR 45.8 (CH2), 114.9, 117.2, 117.8,
122.7, 130.7, 131.52, 132.2, 148.7, 154.9, 166.9 (C=S).
5d: IR (cm-1): 1500 (s, C=N), 1310 (s, C=S); 1H-NMR: 6.84 (2H, d, J=8.5 Hz, arom). 7.08 (2H, d, J=8.5
Hz, arom) 12.49 (1H, s, NH), 4.49 (2H, d, J=5.2 Hz, CH2=CH-CH2-), 5.06 (1H, d, J=17.09 Hz,

Molecules 2001, 6
823
CH2=CH-CH2-), 5.22 (1H, dd, J=0.6 and 10.4 Hz, CH2=CH-CH2-), 5.76 (1H, m, CH2=CH-CH2-), 1.36
13
(3H, t, J=7.0 Hz, -OCH2CH3), 4.00 (2H, q, J=7.0 Hz, -OCH2CH3), 3.96 (2H, s, -CH2-); C-NMR 14.7
(CH3), 31.0 (CH2), 45.7 (CH2), 63.4 (CH2), 114.9 (2 x C), 118.4, 125.0, 129.5 (2 x C), 130.2, 151.6,
158.3, 167.4 (C=S).
Synthesis of potassium salts of substituted dithiocarbazinic acids (4e-f)
A mixture of 3a-d (0.01 mol), CS2 (0.15 mol) and KOH (0.15 mol) in absolute ethanol (350 mL) was
heated under the reflux for 10 hours, cooled to room temperature and diluted with dry ether (200 mL).
The precipitate that appeared was filtered, washed with 2 x 50mL of ether and vacuum dried at 65°C.
Synthesis of 4-amino-5-aryl-1,2,4-triazoles (5e-h)
To a suspension of 4e-h (0.002 mol), hydrazine hydrate (0.04 mol) and water (4 mL) were added
and the mixture was refluxed with stirring for several hours, until the evolution of hydrogen sulfide had
ceased. After dilution with water (100 mL) and acidification with HCl, the precipitates were filtered,
washed with 2 x 30 mL of water and recrystallised from ethanol-water.
5e: IR (cm-1): 3271-3172 (O-H) and (s, NH), 3028 (s, C-H, Ar-H), 1618(s, C-C, Ar-H), 1583 (s, C=N),
1534 (δ, N-H), 1249 (C=S) cm-1; UV 218, 252, 290 nm
5f: IR (cm-1): 3306-3173 (O-H) and (s, NH), 3025-2955 (s, C-H, Ar-H), 1615 (s, C-C, Ar-H), 1514 (s,
C=N), 1480 (δ, N-H), 1266 (C=S) cm-1; UV: 216-218, 252, 288-298 nm;
5g: IR (cm-1): 3287-3152 (O-H) and (s, NH), 3103-3046 (s, C-H, Ar-H), 2938(s, C-H, CH2-), 1626-1599
(s, C-C, Ar-H), 1569 (s, C=N), 1497(δ, N-H), 1228 (C=S) cm-1; UV 228, 254 nm.
5h: IR (cm-1): 3282-3171 (O-H) and (s, NH), 3048(s, C-H, Ar-H), 2972-2788 (s, C-H, CH2-), 1619 (s,
C-C, Ar-H), 1514 (s, C=N), 1260 (C=S) cm-1; UV 228, 256 nm.
Microbiology
The filter paper disc method [14,20] was performed using Sabouraud dextrose broth and Mueller
Hinton broth. These agar media were inoculated with 0.5 mL of the 24 h liquid cultures containing 107
microorganisms/mL. Filter paper discs (5 mm diameter) saturated with solutions of each compound
(concentrations: 1mg/mL; 5mg/mL and 10mg/mL DMSO) were placed on the indicated agar mediums.
The incubation time was 24h at 37°C for bacterial and 48h at 30°C for Candida species. Discs with only
DMSO were used as control. Inhibitory activity was measured (in mm) as the diameter of the observed
inhibition zones. The tests were repeated to confirm the findings and the average of the readings was
taken into consideration.

Molecules 2001, 6
824
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