5-Nitroisatin-derived thiosemicarbazones: Potential antileishmanial agents

Article abstract of DOI:10.3109/14756366.2013.836641

A series of 29 previously reported N⁴-substituted 5-nitroisatin-3-thiosemicarbazones 2-30 has been screened for leishmanicidal potential. Compounds 2-4, 7, 8, 10-13, 15-19, 21, 23, 24, 26, 28 and 30 exhibited good to excellent antileishmanial activities with IC50 values ranging from 0.44±0.02 to 32.38±0.66μg/mL. Of these, 5, 7, 19 and 28 proved to be the most active antileishmanial agents, displaying activities with IC50 values 1.78±0.35, 0.44±0.02, 1.91±0.04 and 4.28±0.75μg/mL, respectively, which were even better than the standard drug, pentamidine (IC50=5.09±0.04μg/mL). This study presents the first example of exhibition of leishmanicidal potential by isatin-thiosemicarbazones and as such furnishes a solid basis for further research on these compounds to develop more potent antileishmanial agents.

Full text of DOI:10.3109/14756366.2013.836641

http://informahealthcare.com/enz
ISSN: 1475-6366 (print), 1475-6374 (electronic)
J Enzyme Inhib Med Chem, Early Online: 1–5
2013 Informa UK Ltd. DOI: 10.3109/14756366.2013.836641
!
ORIGINAL ARTICLE
5-Nitroisatin-derived thiosemicarbazones: potential
antileishmanial agents
Humayun Pervez1, Nazia Manzoor1, Muhammad Yaqub1, and Khalid Mohammed Khan2
2
1Institute of Chemical Sciences, Organic Chemistry Division, Bahauddin Zakariya University, Multan, Pakistan and H.E.J. Research Institute of
Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan
Abstract
Keywords
A series of 29 previously reported N4-substituted 5-nitroisatin-3-thiosemicarbazones 2–30 has
been screened for leishmanicidal potential. Compounds 2–4, 7, 8, 10–13, 15–19, 21, 23, 24, 26,
28 and 30 exhibited good to excellent antileishmanial activities with IC50 values ranging from
0.44 ꢀ 0.02 to 32.38 ꢀ 0.66 mg/mL. Of these, 5, 7, 19 and 28 proved to be the most active
antileishmanial agents, displaying activities with IC50 values 1.78 ꢀ 0.35, 0.44 ꢀ 0.02, 1.91 ꢀ 0.04
and 4.28 ꢀ 0.75 mg/mL, respectively, which were even better than the standard drug,
pentamidine (IC50 ¼ 5.09 ꢀ 0.04 mg/mL). This study presents the first example of exhibition of
leishmanicidal potential by isatin-thiosemicarbazones and as such furnishes a solid basis for
further research on these compounds to develop more potent antileishmanial agents.
Isatin-thiosemicarbazones, leishmanicidal
activity, Leishmania major
History
Received 17 May 2013
Revised 15 August 2013
Accepted 16 August 2013
Published online 3 October 2013
Introduction
antineoplastic, antiplasmodial and antiviral22–34. However, antil-
eishmanial potential of this group of thiosemicarbazones has not
been explored. Very recently, during random screening of the
organic compounds prepared in our laboratory, we found that
certain N4-substituted isatin-thiosemicarbazones bearing strong
inductively electron-attracting substituents at position-5 of the
isatin scaffold exhibited antileishmanial activity. This observation
stimulated us to study the leishmanicidal properties of a series
of 29 previously reported N4-alkyl/alkenyl/aryl substituted
5-nitroisatin-3-thiosemicarbazones35,36, prepared by the conden-
sation of 5-nitroisatin with appropriate thiosemicarbazides
(Scheme 1). This paper, therefore, describes the in vitro
leishmanicidal potential of these compounds. It also describes
the effects of the nature of substituents attached to N4 of the
thiosemicarbazone moiety on this very potential of the com-
pounds. Further studies on such compounds with certain struc-
tural modifications are in progress.
Leishmaniasis is a tropical disease caused by protozoa of the
genus Leishmania. There are four different forms of the disease
with a broad range of chemical manifestations. These include
cutaneous leishmaniasis (CL), diffused cutaneous leishmaniasis
(DCL), mucocutaneous leishmaniasis (MCL) and visceral leish-
maniasis (VL). Of these, the last, being the most severe, causes
almost 100% mortality, if untreated1,2
.
The available chemotherapy for leishmaniasis relies upon
pentavalent antimonial (Sbv) compounds, i.e. sodium stibogluco-
nate (pentostam) or meglumine antimoniate (glucantime), which
even though are still the first-line drugs, but are not totally safe
and/or efficacious3. For the treatment of unresponsive cases,
amphotericin B and pentamidine can be used, though they are not
fully effective either and exhibit adverse side effects4. Miltefosine
or hexadecylphosphocholine, an alkylphospholipid, originally
developed as an anticancer agent, is the only oral antileishmanial
drug found to be effective against both the CL5 and VL6, although
causing serious gastrointestinal problems7. Furthermore, drug-
Materials and methods
resistant strains of Leishmania spp. have appeared, which All reagents and solvents were used as obtained from the
necessitate the search for new, more effective and non- or least suppliers or recrystallized/redistilled as necessary. The
toxic chemotherapeutic agents.
5-nitroisatin-3-thiosemicarbazones were prepared by treating
Thiosemicarbazones are an important class of organic com- 5-nitroisatin with appropriate thiosemicarbazides. The details of
pounds, which possesses a number of medicinal properties, the reactions along with physical, analytical and spectral data of
including antibacterial, antifungal, antiprotozoal, antitumoral, the compounds were reported elsewhere35,36. In vitro leishmani-
antiviral and more particularly, the antileishmanial activities8–21
.
cidal screening of the prepared compounds was made at
Isatin-derived thiosemicarbazones have also been found to Dr. Panjwani Center for Molecular Medicine and Drug
possess a variety of biological activities, such as antimicrobial, Research, H.E.J. Research Institute of Chemistry, University of
Karachi, Karachi, Pakistan.
Address for correspondence: Humayun Pervez, Institute of Chemical
Sciences, Organic Chemistry Division, Bahauddin Zakariya University,
Multan – 60800, Pakistan. Tel: +92 03007318346. Fax: +92 0619210068.
E-mail: pdhpervez@hotmail.com
In vitro antileishmanial activity
Leishmania major were grown in bulk in modified Novy-
MacNeal-Nicolle (NNN) biphasic medium by using normal

2
H. Pervez et al.
J Enzyme Inhib Med Chem, Early Online: 1–5
O
O N
2
O
NNHCSNHR
N
O N
H
2
NH NHCSNHR
2
O
50% EtOH(aq.)-AcOH
Reflux, 2h
N
H
1
2-30
Compounds
R
Compounds
R
F
F
2
3
4
17
CH (CH ) CH
3
2
2 4
18
19
CH CH=CH
2
2
F
H C
Br
3
5
20
21
CH
3
Br
6
7
I
CH
3
22
23
C H
2
5
I
CN
8
9
C H
2
5
24
25
26
H CO
H CO
3
3
10
11
12
OCH
3
OCH
H CO
3
3
OCH
3
F
OCH
3
27
28
F
F
F C
3
13
F
F
F
CF
3
14
15
29
Cl
CF
3
30
–
Cl
16
–
OCF
3
Scheme 1. Synthesis of title compounds 2–30.
physiological saline. Leishmania promastigotes were cultured received only medium, whereas the positive control contained
with Rosewell Park Memorial Institute (RPMI) 1640 medium, varying concentrations of standard leishmanicidal compound,
supplemented with 10% heat inactivated foetal bovine serum. pentamidine. The plate was incubated at 21–22 ꢁC for 72 h. The
Parasites at log phase were centrifuged at 2000 rpm for 10 min culture was examined microscopically on an improved Neubauer
and washed three times with saline at the same speed and time. counting chamber and IC50 values of compounds were calculated
Parasites were diluted with fresh culture medium to a final density by Software Ezfit 5.03 (Perella Scientific, Amherst, NH). All
of 106 cells/mL.
assays were performed in triplicate.
In a 96-well microtiter plate, 180 mL of medium was added in
first row and 100 mL of medium was added in other wells. A 20 mL
of the experimental compound was added in medium and serially
diluted. A 100 mL of parasite culture was in all wells and two rows
were left for negative and positive controls. Negative controls
Results and discussion
This study describes the in vitro determination of the leishma-
N4-substituted
nicidal
effects
of
29
5-nitroisatin-3-

DOI: 10.3109/14756366.2013.836641
5-Nitroisatin-derived thiosemicarbazones
3
Table 1. In vitro antileishmanial activity of compounds 2–30.
19 showed much pronounced activity with an IC50 value of
1.91 ꢀ 0.04 mg/mL. It is pertinent to mention that compound 16,
the only trifluoromethoxy derivative (para-substituted) tested in
the assay, showed leishmanicidal activity comparable with that
of the standard drug, pentamidine (IC50 ¼ 5.74 ꢀ 0.01 versus
5.09 ꢀ 0.04 mg/mL). Amongst the two bromo-substituted com-
pounds 20 and 21, the latter having a para substituent displayed
good antileishmanial activity with an IC50 value of
26.95 ꢀ 0.08 mg/mL, whereas the former with an ortho substituent
exhibited moderate activity (IC50 ¼ 51.20 ꢀ 0.27 mg/mL). In con-
trast, amongst the two iodo-substituted compounds 22 and 23,
compound 23 possessing a para substituent showed significant
leishmanicidal effect (IC50 ¼ 25.93 ꢀ 0.03 mg/mL), while the
ortho-substituted compound 22 demonstrated weak activity
(IC50 ¼ 63.89 ꢀ 1.39 mg/mL). Interestingly, compound 24, the
only cyano derivative (meta-substituted) tested in the assay, was
found to exhibit significant activity (IC50 ¼ 25.86 ꢀ 0.18 mg/mL),
when compared with the corresponding trifluoromethyl derivative
14, which demonstrated weak leishmanicidal influence
(IC50 ¼ 65.53 ꢀ 1.14 mg/mL). Of the remainder active N4-aryl-
substituted compounds 25–28 and 30, compound 25 having
methoxy substituents at ortho, para (2,4) positions of the phenyl
IC50 ꢀ SEM*
(mg/mL)
IC50 ꢀ SEM*
Compounds
Compounds
(mg/mL)
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
74.31 ꢀ 0.69
25.84 ꢀ 0.205
27.14 ꢀ 0.06
1.78 ꢀ 0.35
52.66 ꢀ 0.28
0.44 ꢀ 0.02
29.11 ꢀ 0.70
71.45 ꢀ 0.61
27.37 ꢀ 1.05
32.38 ꢀ 0.66
31.43 ꢀ 0.18
12.98 ꢀ 0.145
65.53 ꢀ 1.14
20.75 ꢀ 0.01
5.74 ꢀ 0.01
5.09 ꢀ 0.04
17
18
19
20
21
22
23
24
25
26
27
28
29
30
12.94 ꢀ 0.02
13.00 ꢀ 0.08
1.91 ꢀ 0.04
51.20 ꢀ 0.27
26.95 ꢀ 0.08
63.89 ꢀ 1.39
25.93 ꢀ 0.03
25.86 ꢀ 0.18
53.65 ꢀ 0.51
26.79 ꢀ 0.90
82.12 ꢀ 0.86
4.28 ꢀ 0.075
4100
15.58 ꢀ 0.11
Pentamidiney
*Standard error of the mean.
yStandard drug for leishmanicidal activity.
ring
displayed
moderate
antileishmanial
activity
thiosemicarbazones 2–30, the synthesis of which has been
reported elsewhere35,36
(IC50 ¼ 53.65 ꢀ 0.51 mg/mL), whereas 26 with the same functions
at ortho, meta (2,5) positions exhibited good activity
(IC50 ¼ 26.79 ꢀ 0.90 mg/mL). This shows that in the case of 25,
substitution of additional methoxy substituent at para position of
the phenyl ring caused significant reduction in activity, as the
respective ortho-substituted compound 10 gave an IC50 value of
27.37 ꢀ 1.05 mg/mL in this assay. However, such an additional
substitution at meta position of the phenyl ring was not found to
cause any considerable change in the activity of compound 26
(IC50 ¼ 27.37 ꢀ 1.05 versus 26.79 ꢀ 0.90 mg/mL). More interest-
ingly, in compound 28, substitution of additional fluoro function
at meta position of the phenyl ring caused pronounced enhance-
ment in the leishmanicidal activity (IC50 ¼ 4.28 ꢀ 0.075 mg/mL),
as the respective ortho-substituted compound 17 gave an IC50
value of 12.94 ꢀ 0.02 mg/mL in the present assay. Furthermore, as
in compound 25, such an additional substitution of fluoro group at
para position of the phenyl ring of compound 27 resulted into a
decrement in its activity but to a level of much higher degree
(IC50 12.94 ꢀ 0.02 mg/mL ! 82.12 ꢀ 0.86 mg/mL). Compound 27
thus proved to be the least active derivative in the present series.
Compound 30, the only dichloro derivative (ortho, para-
substituted) tested in this assay, demonstrated significant activity
(IC50 ¼ 15.58 ꢀ 0.11 mg/mL). These structure–activity relation-
ships (SARs) may serve as a basis for structural modifications
aimed at the development of certain leishmanicidal agents of
medicinal interest/importance.
The exact mechanism of antileishmanial activity displayed by
the test thiosemicarbazones 2–30 is not known. However, it is
generally accepted that the mode of leishmanicidal action of this
class of agents involves primarily the inhibition of cysteine
proteases found in different Leishmania species. Such an enzym-
atic inhibition may be attributed to nucleophilic addition of
the active site cysteine thiol to the thiocarbonyl function of the
thiosemicarbazone moiety, as recently proposed for cruzain, the
related major parasitic cysteine protease from Trypanosomal
cruzi10,12,29. The antileishmanial activity shown by our test
compounds 2–30 may also be attributed to inhibition of the
ribonucleoside diphosphate reductase (RDR), an iron (Fe)-
dependent enzyme catalyzing the rate-limiting step of DNA
synthesis in the parasite. Notably, it is the ability of these
compounds to act as tridentate metal chelators that leads to their
leishmanicidal activity. The chelation of Fe from intracellular Fe
pools results in the inhibition of RDR. The tridentate chelating
.
In vitro antileishmanial activity
The synthetic thiosemicarbazones 2–30 were screened for their
antileishmanial activity according to the literature protocol37.
Compound 2, i.e. 1-(5-nitro-2-oxindolin-3-ylidene)-4-phenylthio-
semicarbazide severed as a reference point to evaluate the effects
of different substituents (alkyl, alkenyl and aryl bearing one or
two functions about the phenyl ring) attached to N4 of the
thiosemicarbazone moiety on the leishmanicidal potential of these
compounds. All the compounds except 29 were found to be active
against Leishmania major, showing varied leishmanicidal activity
(IC50 ¼ 0.44 ꢀ 0.02–82.12 ꢀ 0.86 mg/mL) (Table 1). Compounds
3 and 4 having n-hexyl and allyl substituents at N4 of the
thiosemicarbazone moiety were found to exhibit good antileish-
manial activity (IC50 ¼ 25.84 ꢀ 0.205 and 27.14 ꢀ 0.06 mg/mL,
respectively), whereas 2 bearing phenyl group at the same
position displayed weak activity (IC50 ¼ 74.31 ꢀ 0.69 mg/mL).
Amongst the aryl-substituted compounds 5–7 possessing methyl
substituents at different positions of the phenyl ring, the ortho-
substituted compound 5 exhibited significant activity with an IC50
value of 1.78 ꢀ 0.35 mg/mL, while the para-substituted compound
7 displayed excellent leishmanicidal effect (IC50 ¼ 0.44 ꢀ 0.02 mg/
mL); however, the meta-substituted isomer 6 showed moderate
activity (IC50 ¼ 52.66 ꢀ 0.28 mg/mL). To the contrary, amongst
the ethyl-substituted compounds 8 and 9, the para-substituted
compound 9 was found to demonstrate weak leishmanicidal
activity (IC50 ¼ 71.45 ꢀ 0.61 mg/mL), when compared with the
ortho-substituted compound 8, which displayed good activity
(IC50 ¼ 29.11 ꢀ 0.70 mg/mL). However, all the three methoxy-
substituted compounds 10–12, regardless of the positions of
substituents about the phenyl ring, exhibited good activity with
IC50 values 27.37 ꢀ 1.05, 32.38 ꢀ 0.66 and 31.43 ꢀ 0.18 mg/mL,
respectively. In the cases of trifluoromethyl-substituted com-
pounds 13–15, the ortho- and para-substituted compounds 13 and
15 were found to show significant activity (IC50 ¼ 12.98 ꢀ 0.145
and 20.75 ꢀ 0.01 mg/mL, respectively), when compared with the
meta-substituted compound 14, which exhibited weak activity
(IC50 ¼ 65.53 ꢀ 1.14 mg/mL). On the contrary, all the three
monofluoro-substituted compounds 17–19 demonstrated signifi-
cant activity with IC50 values ranging from 1.91 ꢀ 0.04 to
13.00 ꢀ 0.08 mg/mL. Of these, the para-substituted compound

4
H. Pervez et al.
J Enzyme Inhib Med Chem, Early Online: 1–5
7. Sangraula H, Sharma KK, Rijal S, et al. Orally effective drugs for
Kala-azar (visceral leishmaniasis): focus on miltefosine and
sitamaquine. J Assoc Physicians India 2003;51:686–90.
thiosemicarbazones have been proposed to act by inhibiting
RDR13,38–40. Such compounds have also been proposed to act by
inhibiting dihydrofolate reductase41,42
.
`
`
8. Dodd RH, Ouannes C, Robert-Gero M, et al. Hybrid molecules:
growth inhibition of Leishmania donovani promastigotes by
thiosemicarbazones of 3-carboxy-b-carbolines. J Med Chem 1989;
32:1272–6.
It is only very recently that the thiosemicarbazone-metal
complex, i.e. benzaldehyde thiosemicarbazone derived from
limonene complexed with copper, termed as BenzCo, has been
found to exhibit leishmanicidal activity against the promastigote,
axenic amastigote and intracellular amastigote forms of
Leishmania amazonensis. This leishmanicidal effect demonstrated
by BenzCo was associated with the production of reactive oxygen
species (ROS) leading to mitochondrial dysfunction, ultimately
causing parasite death43.
ROS may lead to oxidative damage of virtually any biomol-
ecule. Mitochondria are particularly susceptible to such a damage
caused by ROS that are continuously generated by the mitochon-
drial respiratory chain44. The generation of ROS can also be
induced by certain drugs, affecting parasite mitochondrial func-
tions45–48. The same principle worked for BenzCo in killing
parasites. The treatment of parasites with BenzCo dose-
dependently generated ROS and enhanced mitochondrial
membrane lipid peroxidation, resulting in irreversible loss of
mitochondrial functions such as mitochondrial respiration,
oxidative phosphorylation and ion transport44.
9. Bharti N, Husain K, Garza MTG, et al. Synthesis and
in vitro antiprotozoal activity of 5-nitrothiophene-2-carboxaldehyde
thiosemicarbazone derivatives. Bioorg Med Chem Lett 2002;12:
3475–8.
10. Du X, Guo C, Hansell E, et al. Synthesis and structure-activity
relationship study of potent trypanocidal thiosemicarbazone inhibi-
tors of the trypanosomal cysteine protease cruzain. J Med Chem
2002;45:2695–707.
11. Beraldo H, Gambino D. The wide pharmacological versatility of
semicarbazones, thiosemicarbazones and their metal complexes.
Mini-Rev Med Chem 2004;4:31–9 and references therein.
12. Aguirre G, Boiani L, Cerecetto H, et al. In vitro activity and
mechanism of action against the protozoan parasite Trypanosoma
cruzi of 5-nitrofuryl containing thiosemicarbazones. Bioorg Med
Chem 2004;12:4885–93.
13. Greenbaum DC, Mackey Z, Hansell E, et al. Synthesis and structure-
activity relationships of parasiticidal thiosemicarbazone cysteine
protease inhibitors against Plasmodium falciparum, Trypanosoma
brucei and Trypanosoma cruzi. J Med Chem 2004;47:3212–19.
14. Husain K, Bhat AR, Azam A. New Pd(II) complexes of the
synthesized 1-N-substituted thiosemicarbazones of 3-indole carbox-
aldehyde: characterization and antiamoebic assessment against
E. histolytica. Eur J Med Chem 2008;43:2016–28.
Conclusions
15. Kandemirli F, Saracoglu M, Cavusoglu I, et al. Structure-activity
relationship study by ETM method on potent trypanocidal
thiosemicarbazone inhibitors of the trypanosomal cysteine protease
cruzain. Phil Nat 2009;1:179–93.
16. Sharma K, Sing R, Fahmi N, et al. Microwave assisted synthesis,
characterization and biological evaluation of palladium and plat-
inum complexes with azomethines. Spectrochim Acta A 2010;75:
422–7.
17. Glinma B, Kpoviessi SDS, Fatondji RH, et al. Synthesis, charac-
terization and anti-trypanosomal activity of R-(-)carvone and
arylketones-thiosemicarbazones and toxicity against Artemia salina
Leach. J App Pharm Sci 2011;8:65–70.
18. Sakirigui A, Kpoviessi SDS, Gbaguidi F, et al. Selective trypanocide
activity of some substituted thiosemicarbazones of citral from benin
Cymbopogon citratus essential oil and their toxicity against Artemia
salina Leach. IJRRAS 2012;12:454–62.
19. Demoro B, Sarniguet C, Sanchez-Delgado R, et al. New organor-
uthenium complexes with bioactive thiosemicarbazones as
co-ligands: potential anti-trypanosomal agents. Dalton Trans 2012;
41:1534–43.
20. Navarro M, Gabbiani C, Messori L, et al. Metal-based drugs for
malaria, trypanosomiasis and leishmaniasis: recent achievements
and perspectives. Drug Discov Today 2010;15:1070–8.
21. Fatondji HR, Kpoviessi S, Gbaguidi F, et al. Structure-activity
relationship study of thiosemicarbazones on an African trypano-
some: Trypanosoma brucei brucei. Med Chem Res 2013;22:
2151–62.
22. da Silva JFM, Garden SJ, Pinto AC. The chemistry of isatins: a
review from 1975 to 1999. J Braz Chem Soc 2001;12:273–324 and
references therein.
23. Pandeya SN, Smitha S, Jyoti M, et al. Biological activities of isatin
and its derivatives. Acta Pharm 2005;55:27–46 and references
therein.
Conclusively, we have demonstrated the potential of
N4-substituted 5-nitroisatin-3-thiosemicarbazones to exhibit antil-
eishmanial activity. To the best of our knowledge, such a group of
compounds has been scarcely studied previously for this activity.
All the compounds of the present series except 29 were found to
be active in the leishmanicidal assay. Of the active compounds,
20, i.e. 2–4, 7, 8, 10–13, 15–19, 21, 23, 24, 26, 28 and 30 displayed
good to excellent antileishmanial activity. Compounds 5, 7, 19 and
28 proved to be potent antileishmanial agents, showing leishma-
nicidal activity even better than the standard drug, pentamidine.
These compounds may represent valid leads for further studies
aimed at the development of efficacious antileishmanial com-
pounds of medicinal interest. The SAR studies revealed that the
antileishmanial potential of the trial compounds depended mainly
on the electronic effects of the substituents attached to N4 of the
thiosemicarbazone moiety. Nevertheless, extensive studies are
required to determine the mechanism by which these compounds
exhibit the leishmanicidal activity.
Declaration of interest
We acknowledge partial funding of this research work and the award of
Indigenous PhD scholarship to NM by Higher Education Commission,
Pakistan.
References
1. Tropical disease research. Progress 1999–2000. Geneva: World
Health Organisation; 2001. Available from: http://www.who.int/tdr/
publications/documents/progress-99-00.pdf [last accessed 12 Sep
2013].
2. Olliaro PL, Bryceson ADM. Practical progress and new drugs for
changing patterns of leishmaniasis. Parasitol Today 1993;9:323–8.
3. Rath S, Trivelin LA, Imbrunito TR, et al. Antimoniais empregados
no tratamento da leishmaniose: Estado da arte. Quim Nova 2003;26:
550–5.
24. Vine KL, Matesic L, Locke JM, et al. Cytotoxic and anticancer
activities of isatin and its derivatives: a comprehensive review from
2000–2008. Anti-Cancer Agents Med Chem 2009;9:397–414 and
references therein.
25. Aboul-Fadl T, Bin-Jubair FAS. Anti-tubercular activity of isatin
derivatives. Int J Res Pharm Sci 2010;1:113–26 and references
therein.
4. McGregor A. WHO warns of epidemic leishmania. The Lancet 26. Chiyanzu I, Hansell E, Gut J, et al. Synthesis and evaluation of
1998;351:575.
isatins and thiosemicarbazone derivatives against cruzain, falcipain-
2 and rhodesain. Bioorg Med Chem Lett 2003;13:3527–30.
27. Chiyanzu I, Clarkson C, Smith PJ, et al. Design, synthesis and anti-
plasmodial evaluation in vitro of new 4-aminoquinoline isatin
derivatives. Bioorg Med Chem 2005;13:3249–61.
5. Soto J, Arana BA, Toledo J, et al. Miltefosine for new world
cutaneous leishmaniasis. Clin Infect Dis 2004;38:1266–72.
6. Prasad R, Kumar R, Jaiswal BP, et al. Miltefosine: an oral drug for
visceral leishmaniasis. Indian J Pediatr 2004;71:143–4.

DOI: 10.3109/14756366.2013.836641
5-Nitroisatin-derived thiosemicarbazones
5
28. Bal TR, Anand B, Yogeeswari P, et al. Synthesis and evaluation of
anti-HIV activity of isatin b-thiosemicarbazone derivatives. Bioorg
Med Chem Lett 2005;15:4451–5.
methylpyridine-2-carboxaldehyde-thiosemicarbazone (3-AMP), 3-
amino-pyridine-2-carboxaldehyde-thiosemicarbazone (3-AP) and
its water-soluble prodrugs. Curr Med Chem 2001;8:121–33.
29. Chibale K. Economic drug discovery and rational medi- 40. Danuta SK, Patricia Q, Richardson DR. Thiosemicarbazones: the
cinal chemistry for tropical diseases. Pure Appl Chem 2005;77: new wave in cancer treatment. Future Med Chem 2009;1:1143–51
1957–64. and references therein.
30. Pirrung MC, Pansare SV, Sarma KD, et al. Combinatorial 41. Lebrun E, Tu YX, van Rapenbusch R, et al. Inhibition of bovine
optimization of isatin-b-thiosemicarbazones as anti-poxvirus
agents. J Med Chem 2005;48:3045–50.
31. Terzioglu N, Karali N, Gursoy A, et al. Synthesis and primary
dihydrofolate reductase and enhancement of methotrexate sensitivity
by N4-(2-acetoxyethoxymethyl)-2-acetylpyridine thiosemicarba-
zone. Biochim Biophys Acta 1990;1034:81–5.
antiviral activity evaluation of 3-hydrazono-5-nitro-2-indolinone 42. Choi I-H, Kim C. Flexible docking of an acetoxyethoxymethyl
derivative of thiosemicarbazone into three different species of
dihydrofolate reductase. Arch Pharm Res 2002;25:807–16.
derivatives. Arkivoc 2006(i):109–18.
32. Quenelle DC, Keith KA, Kern ER. In vitro and in vivo evaluation of
isatin-b-thiosemicarbazone and marboran against vaccinia and 43. Britta EA, Silva APB, Ueda-Nakamura T, et al. Benzaldehyde
cowpox virus infections. Antivir Res 2006;71:24–30.
33. Hall MD, Salam NK, Hellawell JL, et al. Synthesis, activity, and
thiosemicarbazone derived from limonene complexed with copper
induced mitochondrial dysfunction in Leishmania amazonensis.
PLoS One 2012;7:e41440. doi:10.1371/journal.pone.0041440.
pharmacophore development for isatin-b-thiosemicarbazones with
selective activity toward multidrug-resistant cells. J Med Chem 44. Kowaltowski AJ, Vercesi AE. Mitochondrial damage induced by
2009;52:3191–204.
34. Ermut G, Karali N, Cetin I, et al. Synthesis and chemotherapeutic
conditions of oxidative stress. Free Radical Bio Med 1999;26:
463–71 and references therein.
activities of 5-chloro-1H-indole-2,3-dione 3-thiosemicarbazones. 45. Das R, Roy A, Dutta N, Majumder HK. Reactive organic species and
Marmara Pharm J 2013;17:147–54.
imbalance of calcium homeostasis contributes to curcumin induced
programmed cell death in Leishmania donovani. Apoptosis 2008;13:
867–82.
35. Pervez H, Manzoor N, Yaqub M, et al. Synthesis and urease
inhibitory properties of some new N4-substituted 5-nitroisatin-3-
thiosemicarbazones. Lett Drug Des Discov 2010;7:102–8.
36. Pervez H, Manzoor N, Yaqub M, et al. Synthesis and biological
evaluation of some N4-substituted 5-nitroisatin-3-thiosemicarba-
zones. Med Chem Res 2012;21:2251–62.
46. Roy A, Ganguly A, BoseDasgupta S, et al. Mitochondria-dependent
reactive oxygen species-mediated programmed cell death induced by
3,30-diindolylmethane through inhibition of FOF1-ATP synthase in
unicellular protozoan parasite Leishmania donovani. Mol Pharmacol
2008;74:1292–307.
37. Atta-ur-Rahman, Choudhary MI, Thomsen WJ. Bioassay techniques
for drug development. The Netherlands: Harwood Academic 47. Pelizzaro-Rocha KJ, Veiga-Santos P, Lazarin-Bidoia D, et al.
Publishers; 2001:60–4.
38. Finch RA, Liu M-C, Grill SP, et al. Triapine (3-aminopyridine-2-
carboxaldehyde-thiosemicarbazone): a potent inhibitor of ribonu-
Trypanocidal action of eupomatenoid-5 is related to mitochondrion
dysfunction and oxidative damage in Trypanosoma cruzi. Microbes
Infect 2011;13:1018–24.
cleotide reductase activity with broad spectrum antitumor activity. 48. Fonseca-Silva F, Inacio JDF, Canto-Cavalheiro MM, et al. Reactive
Biochem Pharmacol 2000;59:983–91.
39. Li J, Zheng LM, King I, et al. Syntheses and antitumor activities
of potent inhibitors of ribonucleotide reductase: 3-amino-4-
oxygen species production and mitochondrial dysfunction contribute
to quercetin induced death in Leishmania amazonensis. PLoS One
2011;6:e14666. doi:10.1371/journal.pone.0014666.