Structure-activity relationship study of thiosemicarbazones on an African trypanosome: Trypanosoma brucei brucei

Article abstract of DOI:10.1007/s00044-012-0208-6

To explore the structure-activity relationships of thiosemicarbazones on African trypanosome: Trypanosoma brucei brucei, a series of thirty-five thiosemicarbazones (1-35) have been synthesized and characterized by their ¹H NMR, ¹³C NMR, and FT-IR spectra. All compounds were tested for trypanocidal activity using the method "Lilit alamar blue". The comparison of trypanocidal power of thiosemicarbazones was performed considering their structures. This study that was done using acetophenone thiosemicarbazone (1) as basic model, showed that: (a) the presence of lipophilic substituents in para position on benzene ring, (b) substitution of benzene ring and (c) substitution of hydrogen of thioamide function by a phenyl, strongly influence trypanocidal activity. The various modifications to basic structure (1) allowed the synthesis of 1-(4-chlorophenyl) ethylidene-4-phenyl- thiosemicarbazide (34). With a trypanocidal activity of 3.97 μM, this compound is the most active of the series.

Full text of DOI:10.1007/s00044-012-0208-6

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res (2013) 22:2151–2162
DOI 10.1007/s00044-012-0208-6
ORIGINAL RESEARCH
Structure–activity relationship study of thiosemicarbazones
on an African trypanosome: Trypanosoma brucei brucei
•
Houssou Raymond Fatondji Salome Kpoviessi Fernand Gbaguidi
•
•
´
•
•
•
Joanne Bero Veronique Hannaert Joelle Quetin-Leclercq Jacques Poupaert
•
¨
Mansourou Moudachirou Georges Coffi Accrombessi
•
Received: 9 May 2012 / Accepted: 17 August 2012 / Published online: 5 September 2012
Ó Springer Science+Business Media, LLC 2012
Abstract To explore the structure–activity relationships
of thiosemicarbazones on African trypanosome: Trypano-
soma brucei brucei, a series of thirty-five thiosemicarba-
zones (1–35) have been synthesized and characterized by
Keywords Acetophenone-thiosemicarbazone ꢀ
‘‘Lilit alamar blue’’ assay ꢀ Lipophilie ꢀ Trypanocidal
1
their H NMR, 13C NMR, and FT-IR spectra. All com-
pounds were tested for trypanocidal activity using the
method ‘‘Lilit alamar blue’’. The comparison of trypano-
cidal power of thiosemicarbazones was performed con-
sidering their structures. This study that was done using
acetophenone thiosemicarbazone (1) as basic model,
showed that: (a) the presence of lipophilic substituents in
para position on benzene ring, (b) substitution of benzene
ring and (c) substitution of hydrogen of thioamide function
by a phenyl, strongly influence trypanocidal activity. The
various modifications to basic structure (1) allowed the
synthesis of 1-(4-chlorophenyl) ethylidene-4-phenyl-thio-
semicarbazide (34). With a trypanocidal activity of 3.97
lM, this compound is the most active of the series.
Introduction
Thiosemicarbazones are derivatives of aldehydes or
ketones. Many thiosemicarbazones are crystalline solids
used for identification of the corresponding aldehydes or
ketones (Williamson, 1999). However, these small mole-
cules (compared to peptides) have interesting biological
activities. Thiosemicarbnazones are DNA replication and
many proteases inhibitors’. This inhibitory activity justifies
the level of interest given to them in the fight against
microbial and parasitic diseases. Molecules used to treat
these diseases have costs out of reach of poor and in some
cases have high risk of toxicity (Aguirre et al.,
2004).Thiosemicarbazones have many biological activities
such as: antiviral (Garcia et al., 2003), antibacterial (Sau
et al., 2003; Rebolledo et al., 2003; Kasuga et al., 2003),
antimalarial (Klayman et al., 1984), antitumor (Quiroga
et al., 1998, Perez et al., 1999; Easmon et al., 2001; Hall
et al., 2000; Kovala-Demertzi et al., 2002; Afrasiabi et al.,
2003, 2004), anticonvulsant (Pandeya et al., 1998, 1999).
However, the cost of thiosemicarbazones synthesis is not
expensive. In addition, thiosemicarbazones are important
intermediates in drugs synthesis, formation of metal com-
plexes and heterocycles such as thiadiazolines preparation
(Chapleo et al., 1988; Sau et al., 2003).
H. R. Fatondji ꢀ S. Kpoviessi (&) ꢀ G. C. Accrombessi
`
Laboratoire de Chimie Organique Physique et de Synthese,
´
´
Faculte des Sciences et Techniques, Universite d’Abomey-
Calavi, Cotonou BP 4521, Republic of Benin
e-mail: kpovsalome@yahoo.fr
F. Gbaguidi ꢀ M. Moudachirou
´
Laboratoire National de Pharmacognosie/Centre Beninois de la
Recherche Scientifique et Technique, CBRST, Bp 06 Oganla,
Porto-Novo, Republic of Benin
J. Bero ꢀ J. Quetin-Leclercq ꢀ J. Poupaert
´
Louvain Drug Research Institute, LDRI, Universite catholique
Unlike American trypanosome, for which many studies
information regarding were performed on thiosemicarba-
zone derivatives (Du et al., 2002; Fuiji et al., 2005), much
remains to be discovered on the structure–activity rela-
tionship thiosemicarbazones of African trypanosome. Yet
de Louvain, B1 7203, Av. E. Mounier 72, 1200 Brussels,
Belgium
V. Hannaert
Institut de Pathologie Cellulaire Christian Duve, ICP,
73.30, 1200 Brussels, Belgium
123

2152
Med Chem Res (2013) 22:2151–2162
it is a protozoan parasite that affects humans as well as
animals. While Trypanosoma brucei brucei decimate
livestock, Trypanosoma brucei gambiense and Trypano-
soma brucei rhodesiense species are responsible for human
African trypanosomiasis, an endemic disease in sub-Saharan
Africa, with 7139 estimated cases and at-risk population of
60 million people (WHO, 2012).
supporting factor. The trypanosome suspensions were
adjusted to 5 9 10-4 tryp/mL. In each well, 50 lL of
different dilutions of the stock solution were added to
50 lL of suspension of trypanosomes. The plates were
then incubated at 37 °C for 72 h in an atmosphere with
5 % CO2. Then, 10 lL of dye ‘‘Alamar BlueTM’’ is
added to each well and incubated for 4 h. The dye
‘‘Alamar Blue TM’’ is a reagent for detecting enzymatic
activity. The wells in which the concentration of com-
pound is insufficient to inhibit the proliferation of try-
panosomes are stained. The CMI is the concentration of
unstained wells in which there is the lowest amount of
thiosemicarbazone. The plate reading is made by com-
parison with control wells on a fluorescence plate reader
using an excitation wavelength of 530 nm and an emis-
sion wavelength of 590 nm.
The aim of this work is to study the structure–activity
relationships of thiosemicarbazones of ketones and alde-
hydes on Trypanosoma brucei brucei in order to develop
new active molecules in a safer chemotherapeutic approach.
Experimental
Chemistry
Ketones, aldehydes, and thiosemicarbazide hydrochloride
used for synthesis of thiosemicarbazones are sold by Acros
Organics and Aldrich. TLC analyses were performed using
silica gel-precoated plates. The solvent used is dichloro-
methane/ethyl acetate (v/v 2/1). Thiosemicarbazones were
purified by recrystallization in ethanol. Compounds purity
was confirmed by LC/MS in mode APCI on column C18.
The melting points were taken on a fusionometer eletro-
thermal 1A 9000. The spectrometric data were recorded
with the following instruments: IR, Perkin Elmer FT-IR
Toxicity test against Artemia salina (Sleetand Brendel)
Encysted eggs of Artemia salina (10 mg) were incubated in
100 mL of sea water at pH 7–8. After 48 h of incubation,
larvae are collected with a Pasteur pipette. We dissolve the
samples with 1 % DMSO (dimethylsulfoxide). Then, a
series of ten solutions of thiosemicarbazones at varying and
progressive concentration were prepared. A defined number
of larvae were introduced into each solution. All solutions
and even control solutions containing no active substance
are left to stir for 24 h. The number of surviving larvae in
each solution that is counting after 24 h of incubation is
used to evaluate toxicity of solution. In case of death in
control medium, the data is corrected by Abbott’s formula:
% death = ((test - control)/control)) 9 100. The LC50 value
is determined by linear regression.
1
286; H NMR and 13C NMR, Bruker 400. To synthesize
thiosemicarbazones: a mixture of ketone or aldehyde
(20 mmol dissolved in 100 mL of ethanol) and thiosemi-
carbazide (20 mmol dissolved in 20 ml of 1 N hydro-
chloric acid) is stirred until the thiosemicarbazone
precipitates. The precipitate is filtered, dried, and recrys-
tallized in ethanol (96°) to give thiosemicarbazone crystals
(Fig. 1).
Results and discussion
Antitrypanosomal activity (Lilit, Alamar Blue TM)
Chemistry
The test is performed on the bloodstream form of the
strain 427 of Trypanosoma brucei brucei by the ‘‘Lilit
Alamar Blue’’ method (Baltz et al., 1985; Hirumi, 1994;
Thirty-five thiosemicarbazones were synthesized with
yields going from 45 to 95 %.The use of a polar prot-
ic solvent such as ethanol, is good for the reaction.
Yields are generally greater than 70 % except with the
20-chloroacetophenone-thiosemicarbazone (45 %). This is
generally the case of 2-substituted aryl ketones (Du et al.,
2002). The physical and spectrometric data of these
¨
Raz et al., 1997). The stock solutions of thiosemicarba-
zones have been prepared from a standard solution an
initial concentration (10 mg/mL in DMSO). The trypan-
osomes are grown in a medium containing 10 % of heat-
inactivated fetal calf serum and bloodstream form
Fig. 1 Synthesis of
thiosemicarbazones (1–35)
S
S
R3
R2
R2
HN
NH
H3O+, Cl-
O
H2O
+
+
H2N
NH
N
HN
R3
R1
R1
123

Med Chem Res (2013) 22:2151–2162
2153
compounds are reported in Table 1. Thin layer chroma-
tography (TLC) shows that thiosemicarbazones have Rf
ranging from 0.53 to 0.86.
The activities of benzaldehyde thiosemicarbazones are
lower than those of acetophenone thiosemicarbazones.
This means that the methyl group of the acetophenone
thiosemicarbazones plays an important role in trypano-
cidal activity. Its replacement with an ethyl group in the
The spectrometric data are in conformity with the
structures suggested for the products. Thus, IR spectra of
thiosemicarbazones show bands in range of 3,455–3,139
cm-1 due to the stretching vibration of NH. The C=N
40-methoxypropiophenone-thiosemicarbazone (16 IC50
=
132.40 0.67 lM) reduced the trypanocidal activity
compared to that of 4-methoxyacetophenone-thiosemi-
carbazone (2 IC50 = 91.14 7.47 lM).
1
stretching band appears at 1,588 or 1,587 cm-1. In the H
NMR spectra of the most deshielded proton, which is
linked to the central nitrogen atom appears as a broadened
singlet between 8.9 and 11.70 ppm. In 13C NMR spectra,
thiosemicarbazones C=N bond is indicated by chemical
shifts between 145 and 149 ppm while the chemical shift
of the C=S bond appears between 176 and 180 ppm.
The compounds with the halogen substituent in para
position are more active than those that have it in meta
position and they are themselves more active than thio-
semicarbazones with the halogen in ortho position.
It is interesting to note that the 40-(N,N-dimethylamino)-
cinnamaldehyde thiosemicarbazone (29 IC50 = 17.71
3.46 lM) which has the dimethylamino group in para
position is much more active than cinnamaldehyde thio-
semicarbazone (IC50 = 27 76.28 7.37 lM). The reduc-
tion of the exocyclic double bond C=C of cinnamaldehyde
thiosemicarbazone decreases trypanocidal activity for the
3-phenylpropionaldehyde-thiosemicarbazone (28 = 260.21
10.78 lM). The exocyclic double bond C=C plays an
important role in trypanocidal activity.
Biology
Trypanocidal activity of thiosemicarbazones
The synthesized compounds were tested for their trypan-
ocidal activity on Trypanosoma brucei brucei. The test
results are reported in Table 2. The thiosemicarbazone of
acetophenone (1) have an IC50 value of 211.88 7.38
lM. Presence of a chlorine atom in ortho position in
The trypanocidal activity is quite important in the case
of acetonaphthone-thiosemicarbazone (9 IC50 = 9.62
2.67 lM) in which two aromatic nuclei are joined. This
activity decreases when the two nuclei are separated by one
carbon atom. This is the case of benzophenone-thiosemi-
carbazone (31 IC50 = 68.34 0.04 lM). The trypanoci-
dal activity decreases even more when the two nuclei are
separated by three carbon atoms in the case of 1,3-diphe-
nylacetone-thiosemicarbazone (32 IC50 = 146.80 7.24
lM).
We also note that substitution of methyl group of ace-
tophenone thiosemicarbazone (1 IC50 = 211.88 7.38
lM) by a phenyl in the case of benzophenone-thiosemi-
carbazone (31 IC50 = 68.34 0.04 lM) induced an
increase in trypanocidal activity in accordance with the
work of Fujii (2005). Similarly, the substitution of hydro-
gen by a phenyl group on the thioamide function on thio-
semicarbazones 6, 7, and 12 leads to a sharp increase in
trypanocidal activity for compounds 34 (IC50 = 3.97
0.06 lM) and 35 (IC50 = 5.19 0.06 lM) derivatives of
7 and 12, respectively. Again, the compound with the
chlorine in para (34) is more active than that with bromine
in para (35). The thiosemicarbazone 33, derived from 6 is
insoluble.
the thiosemicarbazone of 2-chloroacetophenone (5 IC50
=
199.37 0.83 lM) causes an increase in trypanocidal
activity. Thiosemicarbazone of 4-chloroacetophenone (6 IC50
= 11.06 2.28 lM) showed trypanocidal activity 18 times
that of thiosemicarbazone of 2-chloroacetophenone. With
bromine in meta position, Trypanocidal activity of 3-bro-
moacetophenone-thiosemicarbazone (7) is 70.40 0.25 lM.
This activity is enhanced with a bromine atom in para position
in thiosemicarbazone of 4-bromoacetophenone (8) with a
trypanocidal activity of 26.89 10.86 lM. The presence of a
methoxy group in para position (2 IC50 = 91.14 7.47 lM)
induced an increase of trypanocidal activity compared to
acetophenone thiosemicarbazone. However, the presence of
several methoxy groups on the aryl group decreases the try-
panocidal activity (3, 4). For these thiosemicarbazones of
acetophenone, the presence of halogen or methoxy substitu-
ents in para position increases the trypanocidal activity which
is quite important in the case of chlorine.
The thiosemicarbazones synthesized from benzaldehyde
and its derivatives appear to be less active with IC50 values
greater than 100 lM with the exception of compounds
23 (IC50 = 45.58 7.38 lM) and 13 (IC50 = 82.64
5 lM). The thiosemicarbazone 13 with a chlorine atom in
para position is more active than the thiosemicarbazone 12
which has a chlorine atom in meta position. The latter is
itself more active than compound 11 which has a chlorine
atom in ortho.
The substitution of the aromatic ring of the acetophe-
none thiosemicarbazone (1 IC50 = 211.88 7.38 lM) by
the adamantyl group results in a significant increase in
trypanocidal activity in the case of 1-methyladamantylce-
tone (26 IC50 = 8.38 0.71 lM).
123

2154
Med Chem Res (2013) 22:2151–2162
Table 1 Chemical structure,
yield, and melting point of
synthesized compounds (1–35)
Compounds
1
R1
R2
R3
Yield (%) Rf
M. P (°C)
H
85
89
0.79
0.82
120–121
–CH3
H
H
180–181
224–225
2
3
–CH3
–CH3
O
O
82
74
0.75
0.62
O
O
O
H
215–216
4
–CH3
O
H
H
45
70
0.88
0.82
157–158
194–196
5
6
–CH3
–CH3
Cl
Cl
H
75
0.86
172–173
7
–CH3
Br
H
H
H
H
84
89
65
75
0.80
0.83
0.80
0.88
198–199
182–183
162–163
208–210
8
9
–CH3
–CH3
H
Br
10
11
H
Cl
H
81
0.82
195–196
12
H
Cl
123

Med Chem Res (2013) 22:2151–2162
2155
Table 1 continued
Compounds
13
R1
R2
R3
Yield (%) Rf
M. P (°C)
H
78
0.82
212–213
H
Cl
H
85
0.78
192–193
14
H
O
H
H
H
H
83
78
65
55
0.73
0.80
0.85
0.87
167–168
126–127
169–170
180–181
15
16
17
18
H
O
O
–CH2–CH3
H
H
H
H
H
H
90
95
92
64
0.78
0.67
0.64
0.69
254–255
235–236
229–230
194–195
19
20
21
22
H
H
H
H
NO2
O2
N
OH
O
HO
Cl
H
81
54
0.70
0.71
278–279
160–161
23
24
H
OH
S
N
N
H
NH2
123

2156
Med Chem Res (2013) 22:2151–2162
Table 1 continued
Compounds
25
R1
R2
R3
Yield (%) Rf
M. P (°C)
S
N
N
H
NH2
65
58
0.91
0.90
111–112
H
214–215
26
–CH3
H
H
70
73
0.82
0.75
139–140
114–115
27
28
H
H
H
53
0.88
215–216
29
H
H
N
Br
H
H
H
87
45
88
85
90
0.84
0.98
0.90
–
202–203
169–170
161–162
198–200
155–156
30
31
32
33
34
–CH3
–CH3
–CH3
–
Cl
Br
80
–
154–155
35
123

Med Chem Res (2013) 22:2151–2162
2157
Table 2 Trypanocidal activity of synthesized compounds
Compounds
Trypanocidal activity
Compounds
Trypanocidal activity
Compounds
Trypanocidal activity
1
211.88 7.38
91.14 7.47
–
13
14
15
16
17
18
19
20
21
22
23
24
82.64
–
5
25
26
27
28
29
30
31
32
33
34
35
39.71 10.20
8.38 0.71
76.28 7.37
260.21 10.78
17.71 3.46
135.85 32
68.34 0.04
146.80 7.24
–
2
3
258.80 6.21
132.40 0.67
123.6 7.92
221.50 7.04
–
4
–
5
199.37 0.83
11.06 2.28
70.40 0.25
26.89 10.86
9.62 2.67
443.54 5.85
220 7.68
163.64 7.40
6
7
8
–
9
170.35 9.27
292.53 7.57
45.58 7.38
–
10
11
12
3.97 0.06
5.19 0.06
According to the work of Du and Fujii (2002; 2005),
thiosemicarbazones that have IC50 values between 10 and
100 lM are considered as moderate trypanocidal. The
thiosemicarbazones which have IC50 values below 10 lM
can be considered as active molecules. Indeed, Du found
that macrophage cells are generally sensitive to concen-
trations above 10 lM thiosemicarbazones. Thus, in addi-
tion to inhibiting property of the parasite, they would
preserve the human macrophage host cell (Du et al., 2002;
Fujii et al., 2005). On this basis, thiosemicarbazones 9
(IC50 = 9.62 2.67 lM), 26 (IC50 = 8.38 0.71 lM),
34 (IC50 = 3.97 0.06 lM), and 35 (IC50 = 5.19 0,
06 lM) were selected as good trypanocidal.
Table 3 Selectivity index calculated for active thiosemicarbazones
Compounds
LC50 larve
IC50 parasite
Selectivity index
Thiosemicarbazones
9
26
34
35
480.80
9.62
8.38
3.97
5.19
49.98
14.24
119.33
438.30
134.40
110.40
25.90
Table 4 Thiosemicarbazones and Lipinski’s criteria
Compounds Mol. wt. C log No. of H No. of H
No. of
criteria
met
P
bond
donors
bond
acceptors
The toxicity of thiosemicarbazones 9 (9.62 2.67 lM),
26 (8.38 0.71 lM), 34 (3.97 0.06 lM), and 35
(IC50 = 5.19 0.06 lM) was evaluated on Artemia salina
larvae.
Rule
9
\500
\5
\5
3
\10
3 at least
243.32 3.57
251.39 3.39
319.42 4.87
348.26 5.02
3
3
3
3
All
All
All
3
26
34
35
3
The analysis of the toxicity of Artemia salina larvae also
allows us to determine the selectivity of different mole-
cules by calculating the selectivity index (SI = larvae
LC50/parasite IC50). If the IS value is greater than the unit,
the tested compound is considered to be selective about the
parasites. However, if IS value is less than unity, the
compound in question is more cytotoxic than trypanocidal
(Tiuman et al., 2005). The selectivity index has been cal-
culated for thiosemicarbazones that with IC50 value less
than 100 lM. Table 3 summarizes the results.
3
3
calculated values in Table 4 show that the four most try-
panocidal thiosemicarbazones meet the criteria of Lipinski.
These thiosemicarbazones are good drug candidates.
Table 4 summarizes the results.
To study the structure–activity relationship, Du (2002)
and Fujii (2005) have synthesized several thiosemicarba-
zones such as:
The results of this table show that all thiosemicarba-
zones tested are selective on the parasite Trypanosoma
brucei brucei in addition to their interesting trypanocidal
power (IC50 \ 10 lM). In addition, Lipinski in 1997
brought together some of the properties that he deemed
important to study the pharmacokinetics and drug devel-
opment. A molecule according to three criteria would be
a good pharmacokinetic and be a good drug candidate
(Lipinski et al., 1997). It is interesting to note that the
R
H
N
NH2
Ar
N
Ar: substitued phenyl or not
R: Alkyl
S
They tested their trypanocidal activity in cysteine pro-
tease of T. cruzi. It appears that: The establishment of one
123

2158
Med Chem Res (2013) 22:2151–2162
4-Methoxyacetophenone-thiosemicarbazone (2)
or more halogen atoms or methoxy group on the aromatic
ring Ar, the lengthening of the alkyl radical R (R =
hydrogen, methyl, ethyl, and butyl) considerably increase
the trypanocidal activity. The nature and number of sub-
stituents also seem to have an impact, as well as congestion
induced by the radical R (t-butyl). Our results are similar to
those of Du and Fujii, especially the replacement of
hydrogen (benzaldehyde) by a methyl (acetophenone), the
introduction of halogen or methoxy group on the benzene
ring. However, some differences (nature and position of the
halogen on the aromatic ring) could be explained by the
fact that the trypanosome species tested are not the same.
IR m (KBr cm-1): 3400, 3247, 3162 (NH), 1588 (C=N).
1H NMR d (DMSO-d6 ppm): 2.26 (3H, s, CH3), 3.78
(3H, s, O–CH3), 7.39–7.52 (several signals, 4H of ArH and
1H of NH2) 8.19 (1H, s, NH2) 10.10 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 13.24 (CH3) 54.59
(O–CH3) from 112.94 to 129.45 and 159.61 (Aromatic C),
147.21 (C=N), 178.02 (C=S).
30,40-Dimethoxyacetophenone-thiosemicarbazone (3)
IR m (KBr cm-1): 3376, 3267, 3155 (NH), 1588 (C=N).
1H NMR d (DMSO-d6 ppm): 2.27 (3H, s, CH3), 3.78
(3H, s, O–CH3), 3.82 (3H, s, O–CH3), 6.92–7.51 (3H,
several signals, ArH), 7.88 (1H, s, NH2), 8.22 (1H, s, NH2),
10.06 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 12.95 (CH3) 54.45 (O–
CH3) 54.65 (O–CH3) from 108.60 to 129.19 and 149.12,
147.49 (Aromatic C), 147.19 (C=N), 177.52 (C=S).
Conclusion
This study that is a first of its kind on Trypanosoma brucei
brucei, unlike those made on Trypanosoma cruzi showed
an increase in trypanocidal activity when moving the hal-
ogen (Cl or Br) in ortho position to para position of ben-
zene ring of acetophenone-thiosemicarbazone. It reveals
that the presence of lipophilic substituents in para position
is beneficial for the activity. The replacement of the methyl
group of acetophenone-thiosemicarbazone by hydrogen
decreases the trypanocidal activity. This reduction increa-
ses with the ethyl group. As against the phenyl substituent
instead of methyl increases the activity. When the phenyl
ring of acetophenone-thiosemicarbazone is substituted by
naphthyl group, it follows a significant increase in the
trypanocidal activity. It is the same when it is replaced by
the adamantyl group. The substitution of a hydrogen atom
on thiosemicarbazones thioamide function leads to a sharp
increase in the trypanocidal activity. All these changes
have led to the synthesis of 1-(4-Chlorophenyl) ethylidene-
4-phenyl-thiosemicarbazide (34). With trypanocidal activ-
ity of 3.97 lM, this compound is the most active of the
series.
20,30,40-Trimethoxyacetophenone-thiosemicarbazone (4)
IR m (KBr cm-1): 3341, 3264, 3173 (NH), 1585 (C=N).
1H NMR d (DMSO-d6 ppm): 2.30 (3H, s, CH3), 3.68
(3H, s, O–CH3), 3.84 (6H, s, 2-OCH3) 7, 12 (2H, s, ArH),
7.92 (1H, s, NH2), 8.27 (1H, s, NH2), 10.10 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 12.25 (CH3) 53.98 (2 O–
CH3) 57.91 (O–CH3), 102.24 to 136.70 and 150.51 (Aro-
matic C), 146.12 (C=N), 176.60 (C=S).
20-Chloroacetophenone-thiosemicarbazone (5)
IR m (KBr cm-1): 3400, 3138 (NH), 1587 (C=N).
1H NMR d (DMSO-d6 ppm): 2.28 (3H, s, CH3),
7.38–7.49 (4H, several signals, ArH), 7.62 (1H, s, NH2) 8,
24 (1H, s, NH2), 10.34 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 18.46 (CH3) 127–138
(Aromatic C), 148.44 (C=N), 179.21 (C=S).
Acknowledgments This study was possible thanks to financial and
technical support of the Belgium Kingdom through the BTC that we
thank very sincerely. We also thank Professor Lambert and all the
staff of LDRI at the Catholic University of Louvain.
40-Chloroacetophenone-thiosemicarbazone (6)
IR m (KBr cm-1): 3418, 3139 (NH), 1587 (C=N, C=C).
1H NMR d (DMSO-d6 ppm): 2.29 (3H, s, CH3),
7.41–7.96 (4H, several signals, ArH), 8.00 (1H, s, NH2) 8,
32 (1H, s, NH2), 10.26 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 14.12 (CH3) from 128.42
to 136.74 (Aromatic C), 146.80 (C=N), 179.25 (C=S).
Appendix: Spectral data of thiosemicarbazones
Acetophenone-thiosemicarbazone (1)
IR m (KBr cm-1): 3408, 3233, 3145 (NH), 1587 (C=N).
1H NMR d (CDCl3 ppm): 2.3 (3H, s, CH3), 7.39–7.52
(several signals: 5H of ArH and 1H of NH2), 6.54 (1H, s,
NH2); 8.87 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 12.28 (CH3) from 124.31
to 135.24 (Aromatic C), 146.75 (C=N), 177.21 (C=S).
30-Bromoacetophenone-thiosemicarbazone (7)
IR m (KBr cm-1): 3392, 3212, 3144 (NH), 1588 (C=N,
C=C).
123

Med Chem Res (2013) 22:2151–2162
2159
1H NMR d (DMSO-d6 ppm): 2.28 (3H, s, CH3),
7.34–7.90 and 8.19 (4H, several signals, ArH), 8.11 (1H, s,
NH2), 8.32 (1H, s, NH2), 10.25 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 13.93 (CH3) from 122.01
to 140.01 (Aromatic C), 146.27 (C=N), 179.01 (C=S).
40-Chlorobenzaldehyde-thiosemicarbazone (13)
IR m (KBr cm-1): 3437, 3281, 3165 m (NH), 1600, 1525
(C=N).
1H NMR d (DMSO-d6 ppm): 7.43–7.84 (4H, several
signals, ArH), 8.03 (1H, s, CH=N), 8.07 (1H, s, NH2); 8.24
(1H, s, NH), 11.49 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 128.65–134.22 (Aromatic
C), 140.85 (C=N), 178.06 (C=S).
40-Bromoacetophenone-thiosemicarbazone (8)
IR m (KBr cm-1): 3410, 3193, 3140 (NH), 1587 (C=N,
C=C).
1H NMR d (DMSO-d6 ppm): 2.28 (1H, s, CH3),
7.54–7.90 (4H, several signals, ArH), 8.00 (1H, s, NH2) 8,
32 (1H, s, NH2), 10.33 (1H, s, NH). 13C NMR d (DMSO-d6
ppm): 13.79 (CH3) from 122.68 to 136.83 and 146.59
(Aromatic C), 142.12 (C=N), 178.96 (C=S).
30-Thiosemicarbazone-methoxybenzaldehyde (14)
IR m (KBr cm-1): 3396, 3279, 3155 (NH), 1576 (C=N, C=C).
1H NMR d (DMSO-d6 ppm): 3.80 (1H, s, OCH3),
6.94–7.44 (4H, several signals, ArH), 8.02 (1H, s, CH=N);
8.06 (1H, s, NH2), 8.22 (1H, s, NH2), 11.43 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 55.25 (OCH3), 110.91–
135.57 and 159.54 (Aromatic C), 142.12 (C=N), 177.94 (C=S).
Acetonaphthone-thiosemicarbazone (9)
IR m (KBr cm-1): 3435, 3193 (NH), 1606 (C=N).
1H NMR d (DMSO-d6 ppm): 2.4 (3H, s, CH3),
7.54–7.88 (7H, several signals, ArH), 8.00 (1H, s, NH2) 8,
38 (1H, s, NH2), 10.30 (1H, s, NH).
40-Methoxybenzaldehyde-thiosemicarbazone (15)
IR m (KBr cm-1): 3404, 3290 (NH), 1599, 1537 (C=N).
1H NMR d (DMSO-d6 ppm): 3.78 (3H, s, O–CH3)
6.94–7.74 (4H, several signals, ArH), 7.91 (1H, s, NH2) 8,
01 (1H, s, CH=N), 8.11 (1H, s, NH), 11.32 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 11.89 (CH3) from 122.18
to 133.19 (Aromatic C), 145.71 (C=N), 177.05 (C=S).
13C NMR
d
(DMSO-d6 ppm): 55.91 (OCH3),
Benzaldehyde-thiosemicarbazone (10)
113.29–128.87 and 160.65 (Aromatic C), 142.23 (C=N),
177.59 (C=S).
IR m (KBr cm-1): 3401, 3145 (NH), 1600, 1584 (C=N).
1H NMR d (DMSO-d6 ppm): 7.39–7.79 (5H, several
signals, ArH), 8.00 (1H, s, NH2), 8.06 (1H, s, CH=N); 8.21
(1H, s, NH2), 11.44 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 127.26–134.15 (Aromatic
C), 142.24 (C=N), 177.97 (C=S).
Methoxypropiophenone-40-thiosemicarbazone (16)
IR m (KBr cm-1): 3433, 3278 (NH), 1596 (C=N).
1H NMR d (DMSO-d6 ppm): 1.01 (3H, t, CH3), 2.83
(2H, q, CH2), 3.78 (3H, s, O–CH3), 6.92–7.87 (4H, several
signals, ArH), 7.85 (1H, s, NH2), 8.18 (1H, s, NH2), 10.19
(1H, s, NH).
20-Chlorobenzaldehyde-thiosemicarbazone (11)
13C NMR d (DMSO-d6 ppm): 11.01 (CH3) 19.11 (CH2)
55.17 (O–CH3) from 112.96 to 128.06 and 160.17 (Aro-
matic C) 151, 78 (C=N), 178.70 (C=S).
IR m (KBr cm-1): 3416, 3154 (NH), 1593 (C=N, C=C).
1H NMR d (DMSO-d6 ppm): 7.35–7.42 and 8.28 (4H,
several signals, ArH), 8.11 (1H, s, NH2), 8.31 (1H, s, NH2),
8.47 (1H, s, CH=N), 11.62 (1H, s, NH). 13C NMR d
(DMSO-d6 ppm): 127.28–133.09 (Aromatic C), 138.11
(C=N), 178.21 (C=S).
40-Methylbenzaldehyde-thiosemicarbazone (17)
IR m (KBr cm-1): 3402, 3239, 3156 (NH), 1598 (C=N).
1H NMR d (DMSO-d6 ppm): 2.31 (1H, s, CH3),
7.19–7.68 (4H, several signals, ArH), 8.03 (1H, s, CH=N);
7.94 (1H, s, NH2), 8.18 (1H, s, NH2), 11.38 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 18.83 (CH3) from 124.79
to 137.15 (Aromatic C), 139.92 (C=N), 175.36 (C=S).
30-Thiosemicarbazone-chlorobenzaldehyde (12)
IR m (KBr cm-1): 3392, 3233, 3156 (NH), 1532 (C=N,
C=C).
1H NMR d (DMSO-d6 ppm): 7.41–7.90 (4H, several
signals, ArH), 7.93 (1H, s, CH=N), 8.19 (1H, s, NH2); 8.26
(1H, s, NH2), 11.51 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 125.98–136.45 (Aromatic
C), 140.48 (C=N), 178.17 (C=S).
20-Methylbenzaldehyde-thiosemicarbazone (18)
IR m (KBr cm-1): 3420, 3257, 3156 (NH), 1592 (C=N,
C=C).
123

2160
Med Chem Res (2013) 22:2151–2162
1H NMR d (DMSO-d6 ppm): 2.34 (1H, s, CH3), 7.19–7.26
1H NMR d (DMSO-d6 ppm): 6.86–8.08 (3H, several
signals, ArH), 8.15 (2H, s, NH2), 8.31 (1H, s, CH=N);
10.18 (1H, s, OH), 11.42 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 117.64–130.33 and
155.09 (Aromatic C), 137.37 (C=N), 177.83 (C=S).
and 8.03 (4H, several signals, ArH), 7.83 (1H, s, NH2), 8.19
(1H, s, NH2), 8.40 (1H, s, CH=N), 11.34 (1H, s, NH).
13CNMR d (DMSO-d6 ppm): 18.83 (CH3) from 125.96
to 136.75 and 159.54 (Aromatic C), 141.08 (C=N), 177.82
(C=S).
Cyclohexanone thiosemicarbazone (24)
20-Nitrobenzaldehyde-thiosemicarbazone (19)
IR m (KBr cm-1): 3379, 3215, 3144 (NH), 1585 (C=N).
1H NMR d (DMSO-d6 ppm): 1.54–2.39 (10H, several
signals, CH2 hexane), 7.50 (1H, s, NH2), 7.95 (1H, s, NH2)
10, 13 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 25.01–34.87 (cyclohex-
ane CH2), 156.94 (C=N), 178.49 (C=S).
IR m (KBr cm-1): 3424, 3245, 3159 m (NH), 1539 (C=N,
C=C).
1H NMR d (DMSO-d6 ppm): 7.63–8.02 and 8.41 (4H,
several signals, ArH), 8.11 (1H, s, NH2), 8.39 (1H, s, NH2),
8.47 (1H, s, CH=N), 11.74 (1H, s, NH). 13C NMR d
(DMSO-d6 ppm): 124.44–137.19 (Aromatic C), 148.22
(C=N), 178.45 (C=S).
Carvone-thiosemicarbazone (25)
30-Thiosemicarbazone-nitrobenzaldehyde (20)
IR m (KBr cm-1): 3415, 3259 (NH), 1598 (C=N).
1H NMR d (DMSO-d6 ppm): 1.82 (3H, s, CH3), 1.9 (3H,
s, CH3) 2, 28 (4H, m, 2CH2), 2.68 (1H, q, CH2–CH2–CH),
4.8 (2H, s, =CH2), 5.1 (1H, t, CH=C), 6.3 (1H, s, NH2),
7.81 (1H, s, NH2) 10.3 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 19–22 (CH3) 29–42 (CH2
CH and carvone) 109–150 (=CH and =CH2), 148.29
(C=N), 176.16 (C=S).
IR m (KBr cm-1): 3395, 3242, 3157 (NH), 1604, 1526 (C=N).
1H NMR d (DMSO-d6 ppm): 7.65–8.24 (4H, several
signals, ArH), 8.33 (1H, s, NH2), 8.30 (1H, s, CH=N); 8.63
(1H, s, NH2), 11.61 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 121.32–139.88 (Aromatic
C), 148.33 (C=N), 178.31 (C=S).
20-Hydroxybenzaldehyde-thiosemicarbazone (21)
Methyladamantylcetone-1-thiosemicarbazone (26)
IR m (KBr cm-1): 3443, 3319, 3172 m (NH), 1539 m (C=N).
1H NMR d (DMSO-d6 ppm): 6.79–7.90 (4H, several
signals, ArH), 7.67 (1H, s, NH2), 7.92 (1H, s, NH2) 8, 37
(1H, s, CH=N), 9.86 (OH) 11.37 (1H, s, NH). 13CNMR d
(DMSO-d6 ppm): 114.91–155.28 (Aromatic C), 138.50
(C=N), 176.55 (C=S).
1H NMR d (DMSO-d6 ppm): 1.62–1.71 (15H, several
signals, CH and CH2), 1.98 (3H, s, CH3), 7.30 (1H, s,
NH2); 8.10 (1H, s, NH2), 8.31 (1H, s, CH=N), 9.80 (1H, s,
NH).
13C NMR d (DMSO-d6 ppm): 11.51 (CH3) 27.61–36.17
(several signals CH and CH2) 159.52 (C=N), 178.80 (C=S).
40-Hydroxy-30-thiosemicarbazone-
Cinnamaldehyde thiosemicarbazone (27)
methoxybenzaldehyde (22)
IR m (KBr cm-1): 3418, 3259, 3156 (NH), 1592 (C=N).
1H NMR d (DMSO-d6 ppm): 6.83–7.02 (2H, several
signals, CH=CH), 7.29–7.55 (5H, several signals, ArH),
7.91 (1H, d, CH=N), 7.62 (1H, s, NH2), 8.18 (1H, s, NH2),
11.41 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 125.02–140.84 (Aromatic
C and CH=CH), 144.72 (C=N), 177.67 (C=S).
IR m (KBr cm-1): 3528 (OH), 3437, 3276, 3154 (NH), 1587
(C=N).
1H NMR d (DMSO-d6 ppm): 3.83 (3H, s, CH3),
6.79–7.32 (3H, several signals, ArH), 7.95 (1H, s, CH=N);
7.93 (1H, s, NH2), 8.08 (1H, s, NH2), 9.41 (1H, s, OH),
11.23 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 55.74 (O–CH3) from
109.31 to 140.77 and 148.06 (Aromatic C), 142.89 (C=N),
177.38 (C=S).
40-(N,N-dimethylamino)-cinnamaldehyde
thiosemicarbazone (29)
50-Chloro-20-hydroxybenzaldehyde-thiosemicarbazone
IR (KBr cm-1): 3408, 3245, 3140 m (NH), 1598 m (C=N).
1H NMR d (DMSO-d6 ppm): 2.94 (6H, s, CH3–N–CH3),
6.54–7.38 (6H, several signals, CH=CH and ArH), 7.51
(1H, s, NH2), 7.85 (1H, d, CH=N), 8.05 (1H, s, NH2), 11.24
(1H, s, NH).
(23)
IR m (KBr cm-1): 3405, 3236, 3165 m (NH), 1598, 1565 m
(C=N).
123

Med Chem Res (2013) 22:2151–2162
2161
13C NMR d (DMSO-d6 ppm): 40.14 (CH3–N–CH3)
from 112.00 to 139.81 and 150.66 (Aromatic C), 145.88
(C=N), 177.12 (C=S).
1-(4-Bromophenyl) ethylidene-4-phenyl-
thiosemicarbazide (35)
IR m (KBr cm-1): 3303, 3225 (NH), 1587, 1518 (C=N).
1H NMR d (DMSO-d6 ppm): 2.38 (3H, s, CH3),
7.22–7.90 (9H, several signals, ArH), 10.10 (1H, s, NH-
ArH); 10.65 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 14.23 (CH3) from 122.93
to 139.13 (Aromatic C), 147.67 (C=N), 177.01(C=S).
30-Bromobenzaldehyde-thiosemicarbazone (30)
IR m (KBr cm-1): 3391, 3235, 3155 (NH), 1602, 1532
(C=N).
1H NMR d (DMSO-d6 ppm): 7.22–7.48 and 7.74 (4H,
several signals, ArH), 7.79 (1H, s, CH=N), 7.84 (1H, s,
NH2), 7.87 (1H, s, NH2), 11.51 (1H, s, NH). 13CNMR d
(DMSO-d6 ppm): 122.33–136.65 (Aromatic C), 140.43
(C=N), 178.15 (C=S).
References
Afrasiabi Z, Sinn E, Padhye S, Dutta S, Newton C, Anson CE, Powell
AK (2003) Transition metal complexes of phenanthrenequinone
thiosemicarbazone as potential anticancer agents: synthesis,
structure, spectroscopy, electrochemistry and in vitro anticancer
activity against human breast cancer cell-line T47D. J Inorg
Biochem 95(4):306–314
Afrasiabi Z, Sinn E, Chen JN, Ma YF, Rheingold AL, Zakharov LN,
Rath N, Padhye S (2004) Appended 1,2-naphthoquinones as
anticancer agents 1: synthesis, structural, spectral and antitumor
activities of ortho-naphthoquinone thiosemicarbazone and its
transition metal complexes. Inorg Chim Acta 357(1):271–278
Aguirre G, Boiani M, Cerecetto H, Gerpe A, Gonzalez M, Sainz YF,
Denicola A, Ocariz CO, Nogal JJ, Montero D (2004) In vitro
activity and mechanism of action against the protozoan parasite
Trypanosoma cruzi of 5-nitrofuryl containing thiosemicarba-
zones. Bioorg Med Chem 12:4885–4893
Benzophenone-thiosemicarbazone (31)
IR m (KBr cm-1): 3412, 3248, 3153 (NH), 1609 (C=N).
1H NMR d (DMSO-d6 ppm): 7.35–7.47 (10H, several
signals, ArH), 7.86 (1H, s, NH2), 7.87 (1H, s, NH2) 8, 65
(1H, s, NH).
13C NMR d (DMSO-d6 ppm): 127.55–136.29 (Aromatic
C), 149.06 (C=N), 177.85 (C=S).
1,3-Diphenylacetone-thiosemicarbazone (32)
Baltz T, Baltz D, Giroud C, Crockett J (1985) Cultivation in a semi
defined medium of animal infective forms of Trypanosoma
brucei, T. equiperdum, T. evansi, T. rhodhesiense et T.gamb-
iense. EMBO J 4(5):1273–1277
Chapleo CB, Myers PL, Smith ACB, Stillings MR, Tulloch IF, Walter
SD (1988) Substituted 1,3,4-thiadiazolines with anticonvulsant
activity. 4. Amidines. J Med Chem 31:7
Du X, Guo C, Hansell E, Doyle PS, Caffrey CR, Holler TP,
Mckerrow JH, Cohen FE (2002) Synthesis and structure–activity
relationship study of potent trypanocidal thio semicarbazone
inhibitors of the trypanosomal cysteine protease cruzain. J Med
Chem 45:2695–2707
IR m (KBr cm-1): 3336, 3296, 3228, 3138 (NH), 1601
(C=N).
1H NMR d (DMSO-d6 ppm): 3.48 (1H, s, CH2), 3.75
(1H, s, CH2), 7.12–7.25 (10H, several signals, ArH), 7, 43
(1H, s, NH2), 8.21 (1H, s, NH2), 10.43 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 34.41 (CH2) 42.35 (CH2)
126.53–137.04 (Aromatic C), 152.36 (C=N), 179.03 (C=S).
1-(1-(Naphth-2-yl) ethylidene)-4-
phenylthiosemicarbazide (33)
Easmon J, Purstinger G, Heinisch G, Roth T, Fiebig HH, Holzer W,
¨
Jager W, Jenny M, Hofmann J (2001) Synthesis, cytotoxicity,
IR m (KBr cm-1): 3303, 3237 (NH), 1589, 1520 (C=N).
1H NMR d (DMSO-d6 ppm): 2.53 (3H, s, CH3),
7.24–8.28 (12H, several signals, ArH), 10.17 (1H, s, NH-
ArH); 10.82 (1H, s, NH).
and antitumor activity of copper (II) and iron (II) complexes of
(4) N-azabicyclo [3. 2. 2] nonane thiosemicarbazones derived
from acyldiazines. Med Chem 44:2164
Fujii N, Mallari JP, Hansell EJ, Mackey Z, Doyle P, Zhou YM, Gut J,
Rosenthal PJ, McKerrow JH, Guy RK (2005) Dicovery of potent
thiosemicarbazones inhibitors of rhodesain and cruzain. Bioorg
Med Chem Lett 15:121–123
Garcia CC, Brousse BN, Carlucci MJ, Moglioni AG, Martins AM,
Moltrasio GY, D’Accorso NB, Damonte EB (2003) Inhibitory
effect of thiosemicarbazone derivatives on Junin virus replica-
tion in vitro. Antivir Chem Chemother 14:99–105
13C NMR d (DMSO-d6 ppm): 14.25 (CH3) from 124.77
to 139.22 (Aromatic C), 148.77 (C=N), 177.10 (C=S).
1-(4-Chlorophenyl) ethylidene-4-phenyl-
thiosemicarbazide (34)
Hall IH, Lachey CB, Kistler TD, Durham RW, Jouad EM, Khan M,
Thanh XD, Djebbar-Sid S, Benali-Baitich O, Bouet GM (2000)
Cytotoxicity of copper and cobalt complexes of furfural
semicarbazone and thiosemicarbazone derivatives in murine
and human tumor cell lines. Pharmazie 55(12):937–941
Hirumi K (1994) Axenic culture et African trypanosome bloodstream
forms. Parasitol Today 10(2):80–84
IR m (KBr cm-1): 3303, 3256 (NH), 1590, 1520 (C=N).
1H NMR d (DMSO-d6 ppm): 2.39 (3H, s, CH3),
7.23–8.07 (9H, several signals, ArH), 10.10 (1H, s, NH-
ArH); 10.65 (1H, s, NH).
13C NMR d (DMSO-d6 ppm): 14.22 (CH3) from 125.36
to 139.40 (Aromatic C), 147.54 (C=N), 177.07 (C=S).
Kasuga NC, Sekino K, Ishibawa (2003) Synthesis, crystal structures
and antibacterial activity of monomeric 7-cordinate bismuth (III)
123

2162
Med Chem Res (2013) 22:2151–2162
complexes with tridentate and pentadentate thiosemicarbazones
ligand. Inorg Biochem 96:298
Klayman DL, Scovill JP, Bruce J, Bartosevich JF (1984) 2-Aceth-
ylpyridine thiosemicarbazones derivatives of acethylisoquinoline
as potential antimalarial agents. J Med Chem 27:84
Kovala-Demertzi D, Demertzis MA, Miller JR, Papadopoulou C,
Dodorou C, Filousis G (2002) Structure of bis(2-acetylpyridine
3-hexamethyleneiminylthiosemicarbazonato) palladium (II), a
potential antitumor complex. J Inorg Biochem 92:137
Lipinski CA, Lombardo F, Dominy BW, Feeney PJ (1997) Exper-
imental and computational approaches to estimate solubility and
permeability in drug discovery and development settings. Adv
Drug Delivery Rev 23:3–25
and Pt(II) derived from p-isopropylbenzaldehyde thiosemicar-
bazone with cytotoxic activity in cis-DDP resistant tumor cell
lines. Interaction of these complexes with DNA. J Med Chem
41(9):1399–1408
¨
¨
Raz B, Ten M, Grether-Buhler Y, Kaminsky R, Brun R (1997) The
Alamar cylamino BlueR essay to determine drugs sensitivity of
African trypanosomes (T. b rhodhesiense et T. b gambiense) in
vitro. Acta Trop 68:139–147
Rebolledo AP, de Lima GM, Gambi LN, Speziali NL, Maia DF,
Pinheiro CB, Ardisson JD, Cortes ME, Beraldo Hl (2003) Tin
(IV) complexes of 2-benzoylpyridine N (4)-phenylthiosemicar-
bazone: spectral characterization, structural studies and anti-
fungal activity. Appl Organomet Chem 17:945
Pandeya SN, Mishra Y, Singh PN, Rupainwar DC (1998) Anticon-
vulsant activity of thioureido derivatives of acetophenone
semicarbazone. Pharmacol Res 37:17
Pandeya SN, Aggarwal N, Jain JS (1999) Evaluation of semicarba-
zones for anticonvulsant and sedative-hypnotic properties.
Pharmazie 54:300
Perez JM, Matesanz AI, Martin A, Navaro P, Alonso C, Sousa P
(1999) Synthesis and characterization of complexes of
p-isopropylbenzaldehyde and methyl 2-pyridyl ketone thiosemi-
carbazones with Zn(II) and Cd(II) metallic centers. Cytotoxic
activity and induction of apoptosis in Pam-ras cells. J Inorg
Biochem 75:255–261
Sau DK, Butcher RJ, Chandhuri S, Saha N (2003) Spectroscopic,
structural and antibacterial properties of copper (II) complexes
with bio-relevant 5-methyl-3-formylpyrazole N(4)-benzyl-N(4)
methylthiosemicarbazone. Mol Cell Biochem 253(1–2):21–22
Tiuman TS, Ueda-Nakamura T, Garcia Cortez DA, Dias Filho BP,
Morgado-Diaz JA, de Souza W, Nakamura CV (2005) Antile-
ishmanial activity of Parthenolide, a sesquiterpene lactone
isolated from Tanacetum parthenium. Antimic Agents chemo-
ther 49:176–182
Williamson KL (1999) Macroscale and microscale organic experi-
ments, 3rd edn. Houghto-Mifflin, Boston, pp 426–427. ISBN
0-395-90220-7
´
Quiroga AG, Perez JM, Lopez-Solera I, Montero EI, Masaguer JR,
Luque A, Roman P, Edwards A, Alonso C, Navarro-Ranninger C
´
World Health Organization (2012) Human African trypanosomiasis.
http://www.who.int/trypanosomiasis_african/en/. Accessed 13
May 2012
´
(1998) Novel tetranuclear orthometalated complexes of Pd (II)
123