Synthesis and biological evaluation of novel 2,4-disubstituted-1,3- thiazoles as anti-Candida spp. agents

Article abstract of DOI:10.1016/j.ejmech.2010.10.027

A new series of [4-(4′-substituted-phenyl)thiazol-2-yl]hydrazine derivatives were synthesized in good yield (86-99%) and characterized by elemental analysis, IR, ¹H NMR, and mass spectral studies. The compounds were assayed for their in vitro broad-spectrum antifungal activity, compared to clotrimazole and fluconazole, against 20 clinical isolates of pathogenic Candida spp., representing five different species. The results showed that the presence of heterocyclic or bicyclic rings on hydrazone moiety in position C2 of thiazole revealed a promising selective inhibitory activity especially against Candida albicans and Candida glabrata.

Full text of DOI:10.1016/j.ejmech.2010.10.027

European Journal of Medicinal Chemistry 46 (2011) 378e382
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Short communication
Synthesis and biological evaluation of novel 2,4-disubstituted-1,3-thiazoles
as anti-Candida spp. agents
,
a
a
a
Franco Chimenti a, Bruna Bizzarri a , Adriana Bolasco , Daniela Secci , Paola Chimenti ,
*
Arianna Granese a, Simone Carradori a, Melissa D’Ascenzio a, Daniela Lilli b, Daniela Rivanera b
a Dipartimento di Chimica e Tecnologie del Farmaco, Università degli Studi di Roma “La Sapienza”, P.le A. Moro 5, 00185 Rome, Italy
b Dipartimento di Scienze di Sanità Pubblica e Malattie Infettive, Università degli Studi di Roma “La Sapienza”, P.le A. Moro 5, 00185 Rome, Italy
a r t i c l e i n f o
a b s t r a c t
A new series of [4-(40-substituted-phenyl)thiazol-2-yl]hydrazine derivatives were synthesized in good
yield (86e99%) and characterized by elemental analysis, IR, 1H NMR, and mass spectral studies. The
compounds were assayed for their in vitro broad-spectrum antifungal activity, compared to clotrimazole
and fluconazole, against 20 clinical isolates of pathogenic Candida spp., representing five different species.
The results showed that the presence of heterocyclic or bicyclic rings on hydrazone moiety in position C2 of
thiazole revealed a promising selective inhibitory activity especially against Candida albicans and Candida
glabrata.
Article history:
Received 23 July 2010
Received in revised form
19 October 2010
Accepted 22 October 2010
Available online 29 October 2010
Keywords:
Thiazole
Ó 2010 Elsevier Masson SAS. All rights reserved.
Hydrazone
Candida spp.
Hantzsch reaction
1. Introduction
these studies confirmed that thiazole derivatives are good pharma-
cophores for the design of bioactive molecules [12,13] as bioisoster of
In recent years, epidemiological studies confirm the significant
impact upon human health by infections caused by pathogenic fungi
[1,2]. In fact, although the genus Candida is present as commensal
flora in the majority of healthy people, at the same time it is
a common fungus responsible for opportunistic infections and it can
become pathogenous because of predisposing conditions related to
the host, like immunological compromise (AIDS, anti-cancer therapy,
and transplants), excessive prophylaxis with antimicrobial agents,
and extended use of invasive catheters [3]. Large-scale surveillance
for fungal infections has demonstrated an increasing incidence of
drug-resistant fungal pathogens. As a matter of fact, a significant
number of fungi species (especially Candida glabrata and Candida
krusei) exhibited primary resistance to amphotericin B or was less
susceptible to triazoles [4]. Furthermore, as a consequence of the
toxicity of the currently used polyene antifungal drugs, which leads
to interrupt the therapy, and the emergence of candidal species
resistant to azole-based agents, there is an urgent need for devel-
oping alternative drug therapies [5].
the imidazole ring, and it emerged a different mode of action,
inhibiting the fungal biofilm growth, in relation to azoles and
ampothericin B, a low toxicity profile, and a broad fungicidal spec-
trum [14]. For these reasons and pursuing our research in the field
[15,16], in this paper we report on the synthesis and the biological
evaluation (in vitro antifungal activity and synergy with clo-
trimazole) of a new series of 2,4-disubstituted-1,3-thiazoles bearing
a
bicyclic or heterocyclic ring on double bond C]N and
a 40-substituted (CH3, OCH3) phenyl in position C2 and C4 of thiazole
nucleus, respectively (Table 1). The choiceof these electron-releasing
substituents on the aryl ring derived from the structure-activity
relationships we extrapolated in our previous work [15]. According
to the established guidelines of Clinical and Laboratory Standards
Institute (CLSI) and the European Committe for Antimicrobial
Susceptibility Testing (EUCAST), we assayed the susceptibility of
clinical Candida spp. strains to our compounds by determining their
minimum inhibitory concentration (MIC) [17].
In the recent literature [6e11], (4-aryl-thiazol-2-yl)hydrazines
have been investigated for their significant antimicrobial activity
against a variety of clinically relevant fungal strains. In particular,
2. Chemistry
The new derivatives were synthesized successfully as reported in
our previous communications [15,16,18]. Different carbonyl
compounds were reacted directly with thiosemicarbazide with
catalytic amounts of acetic acid in 2-propanol and the obtained
* Corresponding author. Tel.: þ39 06 49913259; fax: þ39 06 49913772.
E-mail address: bruna.bizzarri@uniroma1.it (B. Bizzarri).
0223-5234/$ e see front matter Ó 2010 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2010.10.027

F. Chimenti et al. / European Journal of Medicinal Chemistry 46 (2011) 378e382
379
Table 1
Chemical and physical data of derivatives 1e28.
R1
N
HN
N
Het
S
R
Comp
Het
R
R1
Mp (ꢁC)
% Yield
ClogPa
Formula
m/z
1
2
3
4
5
6
7
8
Fur-2-yl
Fur-2-yl
Fur-2-yl
Fur-2-yl
H
H
CH3
CH3
H
CH3
OCH3
CH3
OCH3
CH3
OCH3
CH3
OCH3
CH3
OCH3
CH3
OCH3
CH3
OCH3
CH3
OCH3
CH3
OCH3
CH3
OCH3
CH3
OCH3
CH3
OCH3
CH3
OCH3
CH3
193e194
198e199
249e250
229e230
240e241
211e212
252e253
249e250
210e211
219e220
221e222
210e211
230e231
257e258
245e247
265e267
256e258
243e245
209e210
207e208
245e246
233e234
245e247
219e220
226e227
231e232
205e206
235e236
99
99
87
99
99
99
89
86
89
89
86
99
99
86
90
99
88
86
86
87
88
99
88
99
90
99
90
99
4.47
4.00
4.36
3.88
5.04
4.56
4.83
4.35
3.69
3.21
4.06
3.58
3.69
3.21
4.06
3.58
3.69
3.21
6.47
5.99
6.36
3.99
5.54
5.06
5.76
5.29
4.45
3.98
C15H13N3OS
C15H13N3O2S
C16H15N3OS
C16H15N3O2S
C15H13N3S2
C15H13N3OS2
C16H15N3S2
C16H15N3OS2
C17H16N4S
C17H16N4OS
C16H14N4S
C16H14N4OS
C17H16N4S
C17H16N4OS
C16H14N4S
C16H14N4OS
C17H16N4S
C17H16N4OS
C21H17N3S
C21H17N3OS
C22H19N3S
283.34
299.34
297.37
313.37
299.41
315.41
313.44
329.44
308.40
324.40
294.37
310.37
308.40
324.40
294.37
310.37
308.40
324.40
343.44
359.44
357.47
373.47
337.39
353.39
332.42
348.42
375.44
391.44
Thiophen-2-yl
Thiophen-2-yl
Thiophen-2-yl
Thiophen-2-yl
Pyridin-2-yl
Pyridin-2-yl
Pyridin-3-yl
Pyridin-3-yl
Pyridin-3-yl
Pyridin-3-yl
Pyridin-4-yl
Pyridin-4-yl
Pyridin-4-yl
Pyridin-4-yl
Naphthalen-1-yl
Naphthalen-1-yl
Naphthalen-2-yl
Naphthalen-2-yl
Benzodioxol-5-yl
Benzodioxol-5-yl
Indol-3-yl
H
CH3
CH3
CH3
CH3
H
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
H
CH3
CH3
H
H
CH3
CH3
H
H
CH3
CH3
H
H
H
H
CH3
CH3
C22H19N3OS
C18H15N3O2S
C18H15N3O3S
C19H16N4S
C19H16N4OS
C21H17N3O2S
C21H17N3O3S
Indol-3-yl
Coumarin-3-yl
Coumarin-3-yl
OCH3
a
ChemDraw Ultra 8.0.
thiosemicarbazones subsequently were condensed with
a
-
couple of conformers E/Z, each interacting in different way with the
biological target. Diastereoselective dynamic HPLC and theoretical
studies about the E/Z interconversion and the configurational
stability of the thiosemicarbazone derivatives showed that (E)-form
dominated on (Z)-form [19]. The synthesis of some compounds
(5e7, 23, 24, and 26) has been described in previous references
[11,20e23] and was performed with slight changes; their analytical
and spectral data were in full agreement with those reported in the
literature.
bromo-4-methyl/4-methoxyacetophenone to 2,4-disubstituted-
1,3-thiazoles (Hantzsch reaction) as shown in Scheme 1. Our choice
of 2-propanol as solvent let the final products precipitate without
further purification. All synthesized compounds were fully charac-
terized by analytical and spectral data and were listed in Table 1. In
general, they showed in the IR spectrum strong bands at about 3100
and 1590 cmꢀ1 due to the presence of NeH and C]N group,
respectively. In MS spectra, the fragment peaks which correspond to
loss of eCH3 or eOCH3 from the molecular ion are consistent with
the postulated structure. Characteristic M þ 2 isotope peaks relative
to sulphur atom are generally observed in the mass spectra.
Furthermore, because of the hindered rotation of the double bond
around the C]N group, the synthesized products could exist as
3. Pharmacology
Compounds 1e28 were first evaluated for their antifungal
activity against 20 clinical isolates of Candida spp. and compared
with the reference drugs clotrimazole and fluconazole (Table 2).
The used clinical isolates were recently collected from specimens of
patients at the ‘Azienda Policlinico Umberto Iꢁ’ of Rome ‘La Sapi-
enza’ University and were obtained from haematology/oncology
and surgery departments, which also included an intensive care
unit. In particular, the samples were isolated from the upper and
lower respiratory tract, blood, and indwelling venous catheters; the
isolates were identified by conventional methodologies. Prior to
testing, each isolate was subcultered on a qualified medium to
ensure purity and optimal growth.
R'
N
S
NH2
H
N
Het
Het
i
HN
N
ii
Het
N
O
S
R
R
R
Scheme 1. Synthesis of compounds 1e28. Reagents: (i) thiosemicarbazide, 2-prop-
anol, acetic acid (cat.), rt; (ii)
substituents see Table 1.
a-bromo-4-substituted-acetophenone, 2-propanol, rt. For

380
F. Chimenti et al. / European Journal of Medicinal Chemistry 46 (2011) 378e382
Table 2
hand, in the case of C. albicans and glabrata, most of the tested
agents (6e8, 11, 16, 27, and 28) revealed a better selectivity toward
these strains exhibiting an anti-mycotic activity comparable or
higher than that of the reference compounds. As regards the rela-
tionships between the structure of the heterocyclic scaffold and the
detected anti-Candida activity, thiophene (with R]H or CH3),
pyridine (with R]H), and coumarin (with R]CH3) are endowed
with the best in vitro inhibitory activity. As far as the para position
of the aromatic ring (R0) is concerned, the substitution with
a methyl or methoxy group did not influence the activity but there
is an evidence that derivatives bearing a 40-OCH3 moiety could
improve the inhibitory activity.
Furthermore, as depicted in Table 3, the addition of 6, 7, 8, 11, 16,
and 27 derivatives to clotrimazole demonstrated to enhance the
susceptibility of clinical isolates of C. albicans and C. glabrata to
treatment. The best concentrations of the selected compounds and
clotrimazole resulted the lowest MIC values reported in Table 2. In
particular, compounds 6 and 11 gave a 2-fold reduction of the MIC
values against C. albicans with respect to clotrimazole alone at 18 h.
When the MIC end points were determined following 24 and 48 h
of incubation, the observed anti-Candida effect was slightly lower
but it remained constant in time. The reported data suggested that
the combined treatment could lead to an encouraging synergic
effect on the fungal strains’ growth which might be useful to limit
the induction of resistance to clotrimazole and its toxicity.
Minimal inhibitory concentration of compounds 1e28, clotrimazole (C), and fluco-
nazole (F) against 20 clinical strains of Candida species. Antifungal agents were
distributed in the wells of microtiter plates, giving final drug concentrations
between 0.125/256
m
g/ml.
Comp
Tested fungi (MIC values
m
g/mL)
C. kruzei
C. glabrata
(4 strains)
C. albicans
(8 strains)
C. sakè
(2 strains)
C. tropicalis
(3 strains)
(3 strains)
1
2
3
4
5
6
7
8
4e16
4e16
4e16
4e16
0.50e2
0.50e2
2e4
0.50e2
0.50e2
0.50e2
0.50e2
4e32
0.125e2
0.50e2
0.125e2
2e8
0.50e4
0.125e4
4e32
0.50e2
8e64
0.50e8
0.125e2
0.50e4
0.50e4
2e8
4e16
2e8
2e8
32e64
16e64
64e128
16e64
16e64
64e128
32e64
64
16
32
32
16
8e16
32
32
32
32
32
16
16
16e32
32
32
32
32
16e32
32
16
16
16
8e16
8e16
32
8e16
32
64
64e128
64e128
128
64e128
128
128
8
2e4
9
4e16
8e16
0.50e2
16e64
2e8
8e32
4e16
0.50e2
4e16
4e8
16e64
2e8
0.50e2
2e4
4e16
4e16
4e16
0.50e2
0.50e2
2e4
64
64e128
64e128
128
64e128
16
128
64
16
32e64
32e64
16e64
64
4e8
64
16e64
64
64e128
64e128
128
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
C
16e32
32e64
32e64
64
128e256
128e256
16
32
128e256
16
32e64
32e64
256
64e128
64e128
32e64
64
0.125e2
0.50e2
0.125e2
32
0.125e2
2
5. Conclusion
The substitution of the nucleus linked to the hydrazone moiety
had a deep impact on the antifungal activity on this scaffold of
derivatives. Based on the reported results, derivatives 8, 16, 21, and
28 could represent good lead compounds for the development of
novel broad-spectrum anti-Candida spp. agents and they could be
used in association with azole derivatives to enhance their anti-
fungal activity.
128
32e64
4e16
8e32
32
16
32
2e8
4e8
4e16
2e8
4e16
2e8
4e64
F
Furthermore, the most active compounds 6, 7, 8, 11, 16, and 27
(drug concentration range 0.5e4 g/mL) were tested against
m
a number of clinical isolates of C. albicans and C. glabrata in
combination with the most active reference azole (clotrimazole at
6. Experimental protocols
concentration range 0.125e256 mg/mL), to evaluate the possible
The chemicals, solvents for synthesis and spectral grade solvents
were purchased from Aldrich (Italy) and used without further
purification. Melting points (uncorrected) were determined auto-
matically on an FP62 apparatus (Mettler-Toledo). 1H NMR spectra
were recorded at 400 MHz on a Bruker spectrometer using DMSO-
interaction between the substances on the fungal strains’ growth
[24] and to have in this way a preliminary insight of the possible
mechanism of action of this scaffold (Table 3).
4. Results and discussion
d6 as solvent. Chemical shifts are expressed as
d units (parts per
millions) relative to the solvent peak. Coupling constants J are
valued in Hertz (Hz). IR spectra were registered on a PerkineElmer
FT-IR Spectrometer Spectrum 1000 in KBr. Elemental analysis for C,
H, and N were recorded on a PerkineElmer 240 B microanalyzer
and the analytical results were within ꢂ0.4% of the theoretical
values for all compounds. All reactions were monitored by TLC
performed on 0.2 mm thick silica gel plates (60 F254 Merck). Elec-
tron ionization (EI) mass spectra were obtained by a Fisons QMD
The data reported in Table 3 showed that all compounds have
a lower or similar antifungal activity with respect to clotrimazole or
fluconazole against C. kruzei, C. sakè, and C. tropicalis. On the other
Table 3
Effects of the most active compounds on C. albicansa and C. glabratab to sensitivity to
clotrimazole (C).
Comp 18 h, MIC (
m
g/ml)
24 h, MIC (
m
g/ml)
48 h, MIC (mg/ml)
1000 mass spectrometer (70 eV, 200 mA, ion source temperature of
C. albicans C. glabrata C. albicans C. glabrata C. albicans C. glabrata
(4 strains) (2 strains) (4 strains) (2 strains) (4 strains) (2 strains)
200 ꢁC). The samples were introduced directly into the ion source.
C
2
4
2
4
4
2
2
2
4
2
2
2
2
2
2
4
2
4
4
2
2
2
4
2
2
2
2
2
2
8
2
4
4
2
2
2
6.1. General procedure for the synthesis of derivatives 1e28
C þ 6 0.5
C þ 7
C þ 8
1
2
The appropriate carbonyl compound (50 mmol) was dissolved in
100 mL of 2-propanol and stirred with an equimolar quantity of
thiosemicarbazide for 24 h at room temperature with catalytic
amounts of acetic acid. The desired thiosemicarbazone precipitated
from reaction mixture, was filtered, crystallized from suitable
solvent, and dried. Equimolar amounts of the prepared thio-
C þ 11 0.5
C þ 16
C þ 27
1
1
a
C. albicans strains isolated from bronchial washing of transplant patient and
from blood culture of surgery unit’s patient.
b
C. glabrata strains isolated from venous catheter of coronary unit’s patient and
semicarbazone (50 mmol) and
a-bromo-4-methyl- (or 4-methoxy-)
from wound’s swab of surgery unit’s patient. Data are reported at the best
concentrations of selected compounds and reference drug shown in Table 2.
acetophenone (50 mmol), both dissolved in 2-propanol, were

F. Chimenti et al. / European Journal of Medicinal Chemistry 46 (2011) 378e382
381
reacted at room temperature under magnetic stirring for 2 h. The
6.1.10. 1-(1-(Pyridin-3-yl)ethylidene)-2-(4-p-tolylthiazol-2-yl)
precipitate was filtered and dried to give compounds 1e28 in high
yield.
hydrazine (13)
1H NMR (DMSO-d6, 400 MHz)
d
(ppm): 2.33 (s, 3H, ArCH3), 2.49
(s, 3H, N]CeCH3), 7.23e7.24 (m, 2H, Ar), 7.32 (s, 1H, C5H-thiazole),
7.77e7.79 (m, 2H, Ar), 7.99e9.08 (m, 4H, pyridine), 11.50 (bs, 1H,
NH, D2O exch.).
6.1.1. 1-(Furan-2-ylmethylene)-2-(4-p-tolylthiazol-2-yl)hydrazine
(1)
1H NMR (DMSO-d6, 400 MHz)
d (ppm): 2.31 (s, 3H, ArCH3), 6.60
(s, 1H, CH]), 6.79 (s, 1H, C5H-thiazole), 7.19e7.22 (m, 3H, furan),
7.71e7.90 (m, 4H, Ar), 12.27 (bs, 1H, NH, D2O exch.).
6.1.11. 1-(4-(4-Methoxyphenyl)thiazol-2-yl)-2-(1-(pyridin-3-yl)
ethylidene)hydrazine (14)
1H NMR (DMSO-d6, 400 MHz)
d (ppm): 2.40 (s, 3H, N]CeCH3),
6.1.2. 1-(Furan-2-ylmethylene)-2-(4-(4-methoxyphenyl)thiazol-2-
2.49 (s, 3H, OCH3), 6.97e6.99 (d, Jo ¼ 8.0 Hz, 2H, Ar), 7.37 (s, 1H,
C5H-thiazole), 7.80e7.82 (d, Jo ¼ 8.0 Hz, 2H, Ar), 8.24e8.25 (m, 2H,
pyridine), 8.86e8.87 (m, 2H, pyridine),12.45 (bs,1H, NH, D2O exch.).
yl)hydrazine (2)
1H NMR (DMSO-d6, 400 MHz)
d (ppm): 3.77 (s, 3H, OCH3),
6.59e6.61 (m, 1H, furan), 6.79e6.80 (m, 1H, Ar), 6.94e6.97 (m,
2H, furan), 7.13 (s, 1H, CH]), 7.75e7.79 (m, 2H, Ar), 7.91e7.92 (m,
1H, Ar), 11.95 (bs, 1H, NH, D2O exch.).
6.1.12. 1-(Pyridin-4-ylmethylene)-2-(4-p-tolylthiazol-2-yl)
hydrazine (15)
1H NMR (DMSO-d6, 400 MHz)
d (ppm): 2.31 (s, 3H, ArCH3),
6.1.3. 1-(1-(Furan-2-yl)ethylidene)-2-(4-p-tolylthiazol-2-yl)
7.23e7.24 (m, 2H, Ar), 7.40 (s, 1H, C5H-thiazole), 7.62e7.64 (m, 2H,
Ar), 7.90e7.93 (m, 2H, pyridine), 8.06e8.08 (m, 1H, CH]),
8.75e8.78 (m, 2H, pyridine), 12.00 (bs, 1H, NH, D2O exch.).
hydrazine (3)
1H NMR (DMSO-d6, 400 MHz)
d (ppm): 2.25 (s, 3H, ArCH3), 2.52
(s, 3H, N]CeCH3), 7.04 (s, 1H, C5H-thiazole), 7.21e7.28 (m, 3H,
furan), 7.73e7.80 (m, 4H, Ar), 11.48 (bs, 1H, NH, D2O exch.).
6.1.13. 1-(4-(4-Methoxyphenyl)thiazol-2-yl)-2-(pyridin-4-
ylmethylene)hydrazine (16)
6.1.4. 1-(1-(Furan-2-yl)ethylidene)-2-(4-(4-methoxyphenyl)
1H NMR (DMSO-d6, 400 MHz)
d (ppm): 3.78 (s, 3H, OCH3),
thiazol-2-yl)hydrazine (4)
6.97e6.99 (m, 2H, Ar), 7.33 (s, 1H, C5H-thiazole), 7.78e7.80 (m, 2H,
Ar), 8.09e8.10 (m, 2H, pyridine), 8.12 (s, 1H, CH]), 8.80e8.81 (m,
2H, pyridine), 13.30 (bs, 1H, NH, D2O exch.).
1H NMR (DMSO-d6, 400 MHz)
d (ppm): 2.23 (s, 3H, N]CeCH3),
3.77 (s, 3H, OCH3), 6.57e6.58 (m, 1H, furan), 6.82e6.83 (m, 1H,
furan), 6.95e6.97 (m, 1H, furan), 7.12 (s, 1H, CH]), 7.76e7.79 (m,
4H, Ar), 11.95 (bs, 1H, NH, D2O exch.).
6.1.14. 1-(1-(Pyridin-4-yl)ethylidene)-2-(4-p-tolylthiazol-2-yl)
hydrazine (17)
6.1.5. 1-(4-(4-Methoxyphenyl)thiazol-2-yl)-2-(1-(thiophen-2-yl)
1H NMR (DMSO-d6, 400 MHz)
d (ppm): 2.32 (s, 3H, ArCH3), 2.37
ethylidene)hydrazine (8)
(s, 3H, N]CeCH3), 7.24e7.25 (m, 2H, Ar), 7.39 (s, 1H, C5H-thiazole),
7.77e7.78 (m, 2H, Ar), 8.20e8.21 (m, 2H, pyridine), 8.85e8.86 (m,
2H, pyridine), 12.00 (bs, 1H, NH, D2O exch.).
1H NMR (DMSO-d6, 400 MHz)
d (ppm): 2.33 (s, 3H, N]CeCH3),
2.49 (s, 3H, OCH3), 6.95e7.07 (m, 3H, thiophene), 7.12 (s, 1H, C5H-
thiazole), 7.38e7.40 (m, 2H, Ar), 7.77e7.79 (m, 2H, Ar), 11.02 (bs, 1H,
NH, D2O exch.).
6.1.15. 1-(4-(4-Methoxyphenyl)thiazol-2-yl)-2-(1-(pyridin-4-yl)
ethylidene)hydrazine (18)
6.1.6. 1-(1-(Pyridin-2-yl)ethylidene)-2-(4-p-tolylthiazol-2-yl)
1H NMR (DMSO-d6, 400 MHz)
d (ppm): 2.36 (s, 3H, N]CeCH3),
hydrazine (9)
3.79 (s, 3H, OCH3), 6.97e6.99 (m, 2H, Ar), 7.38 (s, 1H, C5H-thiazole),
7.80e7.82 (m, 2H, Ar), 8.11e8.12 (m, 2H, pyridine), 8.79e8.80 (m,
2H, pyridine), 12.01 (bs, 1H, NH, D2O exch.).
1H NMR (DMSO-d6, 400 MHz)
d (ppm): 2.34 (s, 3H, ArCH3), 2.50
(s, 3H, N]CeCH3), 7.74e7.78 (m, 4H, Ar), 7.09 (s, 1H, C5H-thiazole),
8.40e8.42 (m, 4H, pyridine), 12.20 (bs, 1H, NH, D2O exch.).
6.1.16. 1-(Naphthalen-1-ylmethylene)-2-(4-p-tolylthiazol-2-yl)
6.1.7. 1-(4-(4-Methoxyphenyl)thiazol-2-yl)-2-(1-(pyridin-2-yl)
hydrazine (19)
ethylidene)hydrazine (10)
1H NMR (DMSO-d6, 400 MHz)
d (ppm): 2.33 (s, 3H, ArCH3),
1H NMR (DMSO-d6, 400 MHz)
d
(ppm): 2.41 (s, 3H, N]CeCH3),
7.21e7.23 (m, 1H, C5H-thiazole), 7.54e8.28 (m, 11H, Ar), 8.98e9.00
(m, 1H, CH]), 11.50 (bs, 1H, NH, D2O exch.).
3.78 (s, 3H, OCH3), 6.97e7.00 (m, 2H, Ar), 7.23 (s, 1H, C5H-thiazole),
7.55e7.56 (m, 1H, Ar), 7.80e7.82 (m, 2H, pyridine þ Ar), 8.07e8.14
(m, 2H, pyridine), 8.63e8.64 (m, 1H, pyridine), 11.55 (bs, 1H, NH,
D2O exch.).
6.1.17. 1-(4-(4-Methoxyphenyl)thiazol-2-yl)-2-(naphthalen-1-
ylmethylene)hydrazine (20)
1H NMR (DMSO-d6, 400 MHz)
d (ppm): 3.79 (s, 3H, OCH3),
6.1.8. 1-(Pyridin-3-ylmethylene)-2-(4-p-tolylthiazol-2-yl)hydrazine
7.19e7.22 (m, 1H, C5H-thiazole), 7.59e7.60 (m, 3H, Ar), 7.79e7.81
(m, 3H, Ar), 7.99e8.00 (m, 3H, Ar), 8.52e8.53 (m, 2H, Ar), 8.68e8.69
(m, 1H, CH]), 12.23 (bs, 1H, NH, D2O exch.).
(11)
1H NMR (DMSO-d6, 400 MHz)
d (ppm): 2.32 (s, 3H, ArCH3),
7.23e7.26 (m, 2H, Ar), 7.33 (s, 1H, C5H-thiazole), 7.75e7.78 (m, 2H,
Ar), 7.85e7.87 (m, 1H, pyridine), 8.13e8.15 (m, 1H, CH]), 8.56e8.67
(m, 3H, pyridine), 12.65 (bs, 1H, NH, D2O exch.).
6.1.18. 1-(1-(Naphthalen-2-yl)ethylidene)-2-(4-p-tolylthiazol-2-yl)
hydrazine (21)
1H NMR (DMSO-d6, 400 MHz)
d (ppm): 2.32 (s, 3H, ArCH3), 2.44
6.1.9. 1-(4-(4-Methoxyphenyl)thiazol-2-yl)-2-(pyridin-3-
(s, 3H, N]CeCH3), 7.30 (s, 1H, C5H-thiazole), 7.99e8.40 (m, 11H,
ylmethylene)hydrazine (12)
Ar), 11.45 (bs, 1H, NH, D2O exch.).
1H NMR (DMSO-d6, 400 MHz)
d (ppm): 3.78 (s, 3H, OCH3),
6.96e6.98 (m, 2H, Ar), 7.23 (s, 1H, C5H-thiazole), 7.76e7.79 (m, 2H,
Ar), 7.80 (s, 1H, CH]), 8.12e8.13 (m, 1H, pyridine), 8.48e8.50 (m,
1H, pyridine), 8.76e8.78 (m, 1H, pyridine), 9.00e9.02 (m, 1H,
pyridine), 12.45 (bs, 1H, NH, D2O exch.).
6.1.19. 1-(4-(4-Methoxyphenyl)thiazol-2-yl)-2-(1-(naphthalen-2-
yl)ethylidene)hydrazine (22)
1H NMR (DMSO-d6, 400 MHz)
d
(ppm): 2.44 (s, 3H, N]CeCH3),
3.78 (s, 3H, OCH3), 6.98e7.00 (m, 2H, Ar), 7.30 (s, 1H, C5H-thiazole),

382
F. Chimenti et al. / European Journal of Medicinal Chemistry 46 (2011) 378e382
7.51e7.52 (m, 2H, Ar), 7.75e7.85 (m, 5H, Ar), 8.10e8.15 (m, 1H, Ar),
8.27e8.32 (m, 1H, Ar), 11.45 (bs, 1H, NH, D2O exch.).
Acknowledgments
This work was supported by grants from FIRB Project 2006
(RBIP067F9E).
6.1.20. 1-((1H-Indol-3-yl)methylene)-2-(4-p-tolylthiazol-2-yl)
hydrazine (25)
1H NMR (DMSO-d6, 400 MHz)
d (ppm): 2.32 (s, 3H, ArCH3),
Appendix. Supplementary data
7.21e7.22 (m, 1H, Ar), 7.50 (s, 1H, C5H-thiazole), 7.70e7.73 (m, 3H,
Ar), 7.80e7.82 (m, 3H, Ar), 8.20e8.23 (m, 1H, Ar), 8.20e8.21 (m, 1H,
C2H-indole), 8.40 (s, 1H, CH]), 11.50 (bs, 1H, NH, D2O exch.).
Supplementary data associated with this article can be found in
the online version, at doi:10.1016/j.ejmech.2010.10.027.
6.1.21. 1-(1-(2-Oxo-2H-chromen-3-yl)ethylidene)-2-(4-p-tolylthiazol-
References
2-yl)hydrazine (27)
1H NMR (DMSO-d6, 400 MHz)
d (ppm): 2.07 (s, 3H, ArCH3), 2.27
[1] S.K. Fridkin, D. Kaufman, J.R. Edwards, S. Shetty, T. Horan, Pediatrics 117
(2006) 1680e1687.
(s, 3H, N]CeCH3), 7.40e7.42 (m, 2H, Ar), 7.50e7.52 (m, 1H, C5H-
thiazole), 7.54e7.57 (m, 2H, Ar), 7.61e7.75 (m, 4H, Ar), 8.20 (s, 1H,
CH]), 11.30 (bs, 1H, NH, D2O exch.).
[2] M.D. Richardson, J. Antimicrob. Chemother. 56 (Suppl. 1) (2005) 5e11.
[3] A.C. Pasqualotto, D.W. Denning, J. Antimicrob. Chemother. 61 (2008) i19ei30.
[4] K. Gulshan, W.S. Moye-Rowley, Eukaryot. Cell 6 (2007) 1933e1942.
[5] P.M. Pinto, R. de Cássia Bothelho Weikert-Oliveira, J.P. Lyon, V.F. Cury,
R.R. Arantes, C.Y. Koga-Ito, M.A. Resende, Microbiol. Res. 163 (2008) 579e585.
[6] A. Cukurovali, I. Yilmaz, S. Gur, C. Kazaz, Eur. J. Med. Chem. 41 (2006)
201e207.
[7] E. Maccioni, M.C. Cardia, L. Bonsignore, A. Plumitallo, M.L. Pellerano, A. De
Logu, Il Farmaco 57 (2002) 809e817.
[8] A. Özdemir, G. Turan-Zitouni, Z.A. Kaplancikli, F. Demirci, G. Iscan, J. Enzym.
Inhib. Med. Chem. 23 (2008) 470e475.
6.1.22. 1-(1-(2-Oxo-2H-chromen-3-yl)ethylidene)-2-(4-(4-
methoxyphenyl)thiazol-2-yl)hydrazine (28)
1H NMR (DMSO-d6, 400 MHz)
d (ppm): 2.49 (s, 3H, N]CeCH3),
3.94 (s, 3H, OCH3), 6.95e6.97 (m, 2H, Ar), 7.17 (s, 1H, C5H-thiazole),
7.37e7.40 (m, 2H, Ar), 7.44e7.45 (m, 1H, Ar), 7.61e7.78 (m, 3H, Ar),
7.90e8.10 (m, 1H, CH]), 11.45 (bs, 1H, NH, D2O exch.).
[9] P. Karegoudar, M.S. Karthikeyan, D.J. Prasad, M. Mahalinga, B.S. Holla,
N.S. Kumari, Eur. J. Med. Chem. 43 (2008) 261e267.
[10] G. Turan-Zitouni, J.A. Fehrentz, P. Chevallet, J. Martinez, Z.A. Kaplancikli,
A. Özdemir, M. Arslanyolu, M.T. Yildiz, Arch. Pharm. Chem. Life Sci. 340 (2007)
310e314.
6.2. Antifungal activity
[11] S.K. Bharti, G. Nath, R. Tilak, S.K Singh, Eur. J. Med. Chem. 45 (2010) 651e660.
[12] M.V. Nora De Souza, J. Sulfur Chem. 26 (2005) 429e449.
[13] P. Vicini, A. Geronikaki, M. Incerti, F. Zani, J. Dearden, M. Hewitt, Bioorg. Med.
Chem. 16 (2008) 3714e3724.
[14] A. De Logu, M. Saddi, M.C. Cardia, R. Borgna, C. Sanna, B. Saddi, E. Maccioni, J.
Antimicrob. Chemother. 55 (2005) 692e698.
[15] F. Chimenti, B. Bizzarri, D. Secci, A. Bolasco, R. Fioravanti, P. Chimenti,
A. Granese, S. Carradori, D. Rivanera, D. Lilli, A. Zicari, S. Distinto, Bioorg. Med.
Chem. Lett. 17 (2007) 4635e4640.
[16] F. Chimenti, S. Carradori, D. Secci, A. Bolasco, P. Chimenti, A. Granese,
B. Bizzarri, J. Heterocycl. Chem. 3 (2009) 575e578.
[17] National Committee for Clinical Laboratory Standards, Performance Standards
for Antimicrobial Susceptibility Testing Supplement M100-S13. National
Committee for Clinical Laboratory Standards, Wayne, PA, 2003.
[18] F. Chimenti, E. Maccioni, D. Secci, A. Bolasco, P. Chimenti, A. Granese,
S. Carradori, S. Alcaro, F. Ortuso, M. Yáñez, F. Orallo, R. Cirilli, R. Ferretti, F. La
Torre, J. Med. Chem. 51 (2008) 4874e4880.
All derivatives were dissolved in dimethylsulfoxide (DMSO). The
in vitro antifungal activities were determined with the broth
microdilution method with Sabouraud dextrose broth (BBL Micro-
biology Systems, Cockeysville, MD) as recommended by the NCCLS
[17]. Microtiter plates containing serial dilutions of each compound
wereinoculated with each organism toyield the appropriate density
(103/mL) in a 100
mL final volume; each plate included positive
controls (fungi without a compound) and a negative control
(medium only). The plates were incubated for 24 h at 37 ꢁC. The MIC
for all isolates was defined as the lowest concentration of antifungal
agents that completely inhibited the growth of the organism, as
detected by unaided eye.
[19] R. Cirilli, R. Ferretti, F. La Torre, D. Secci, A. Bolasco, S. Carradori, M. Pierini,
J. Chromatogr. A 1172 (2007) 160e169.
[20] S.M. Mohamed, M. Unis, H. El-Hady, Indian J. Chem. Sect B Org. Chem. Incl.
Med. Chem. 45B (2006) 1453e1462.
6.3. Broth microdilution susceptibility test method
[21] M.S. Solanki, J.P. Trivedi, J. Indian Chem. Soc. 49 (1972) 37e39.
[22] F. Castelh, M.T. Cambria, P. Mazzone, R. Pignatello, Thermochim. Acta 302
(1997) 143e150.
[23] G. Raciti, P. Mazzone, A. Raudino, G. Mazzone, A. Cambria, Bioorg. Med. Chem.
3 (1995) 1485e1491.
[24] National Committee for Clinical Laboratory Standard, Reference Method for
Broth Dilution Antifungal Susceptibility Testing of Yeasts: Approved Standard,
second ed., Document M27-A2 National Committee for Clinical Laboratory
Standard, Wayne, PA.
The yeast inoculum was adjusted to
a concentration of
0.5e2.5 ꢃ103 CFU/mL in RPMI medium, and an aliquot of 0.1 mL
was added to each well of the microdilution plate. The plates were
incubated at 35 ꢁC, the MIC end points were read visually following
18, 24, and 48 h of incubation and were defined as the lowest
concentration that produced a prominent decrease in turbidity
compared with that of the drug-free growth control.