Synthesis, characterization, antiamoebic activity and cytotoxicity of novel series of pyrazoline derivatives bearing quinoline tail

Article abstract of DOI:10.1016/j.ejmech.2010.07.028

The cyclization of chalcones (1a-1j) with 2-(quinolin-8-yloxy) acetohydrazide (2) under basic condition led to the formation of new compounds, pyrazoline derivatives (3a-3j). In vitro antiamoebic activity was performed against HM1: IMSS strain of Entamoeba histolytica. The results showed that the compounds 3d, 3g, 3h, and 3j exhibited promising antiamoebic activity (IC ₅₀ = 0.05 μM, 0.31 μM, 0.06 μM, 0.29 μM) respectively than the standard drug metronidazole (IC₅₀ = 1.84 μM). The toxicological studies of these compounds on human breast cancer MCF-7 cell line showed that all the compounds 3d, 3g, 3h, 3j and metronidazole were nontoxic at the concentration range of 1.56-50 μM.

Full text of DOI:10.1016/j.ejmech.2010.07.028

European Journal of Medicinal Chemistry 45 (2010) 4669e4675
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Short communication
Synthesis, characterization, antiamoebic activity and cytotoxicity of novel series of
pyrazoline derivatives bearing quinoline tail
,
Faisal Hayat a, Attar Salahuddin a, Sadiq Umar b, Amir Azam a
*
a Department of Chemistry, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025 India
b Department of Toxicology, Jamia Hamdard, Hamdard Nagar, New Delhi 110062 India
a r t i c l e i n f o
a b s t r a c t
Article history:
The cyclization of chalcones (1ae1j) with 2-(quinolin-8-yloxy) acetohydrazide (2) under basic condition
led to the formation of new compounds, pyrazoline derivatives (3ae3j). In vitro antiamoebic activity was
performed against HM1: IMSS strain of Entamoeba histolytica. The results showed that the compounds
Received 9 March 2010
Received in revised form
15 July 2010
Accepted 15 July 2010
Available online 23 July 2010
3d, 3g, 3h, and 3j exhibited promising antiamoebic activity (IC50 ¼ 0.05
respectively than the standard drug metronidazole (IC50 ¼ 1.84 M). The toxicological studies of these
compounds on human breast cancer MCF-7 cell line showed that all the compounds 3d, 3g, 3h, 3j and
metronidazole were nontoxic at the concentration range of 1.56e50 M.
mM, 0.31 mM, 0.06 mM, 0.29 mM)
m
m
Keywords:
Ó 2010 Elsevier Masson SAS. All rights reserved.
Pyrazoline derivatives
Entamoeba histolytica
MTT assay
1. Introduction
Considering these problems, there is a pressing need for a new
effective drug to treat these infections.
Human infections with Entamoeba histolytica may results in
different clinical out comes such as asymptomatic gut colonization,
amoebic colitis or extra intestinal abscess formation in various
organs [1,2]. The prevalence of infection is higher than 5e10% in
endemic areas [3] and sometimes as high as 55% [4]. The highest
prevalence is found in developing countries in the tropics, partic-
ularly in Mexico, India, Central and South America and tropical
areas of Asia and Africa. Occasionally, E. histolytica trophozoites
penetrate the intestinal mucosa, causing amoebic colitis and spread
via portal circulation to other organs, most commonly to the liver,
where they induce amoebic liver abscess (ALA), the most common
extra intestinal manifestation of invasive amoebiasis [5]. Majority
of amoebic liver abscess patients have a single abscess of variable
sizes located in the right lobe, predominantly with in segment six
to eight [6]. In most cases, amoebic liver abscess can be efficiently
treated by intake of metronidazole alone [7], but the recent studies
have shown that this drug have several toxic effects such as gen-
otoxicity, gastric mucus irritation, and spermatozoid damage [8,9].
Furthermore, failures in the treatment of several intestinal proto-
zoan parasites may result from drug resistant to parasites [10,11].
The study of pyrazolines has become of much interest on
account of their diverse biological properties such as antitumor,
immunosuppressive, antibacterial, anti-inflammatory, anticancer,
antidiabetic, and antidepressant properties [12e18]. The recent
success of pyrazole COX-2 inhibitor [19] has further highlighted the
importance of these heterocycles in medicinal chemistry.
A
systematic investigation of this class of compounds revealed that
pyrazole containing pharmacoactive agents play important role in
medicinal chemistry.
The quinoline nucleus occurs in several natural compounds
(cinchona alkaloids) and pharmacologically active substances, dis-
playing a broad range of biological activity [20]. In recent years it is
reported that the incorporation of quinoline nucleus could alter the
course of reaction as well as the biological properties [21,22].
Prompted by the above mentioned biological properties of
pyrazoline and quinoline incorporating heterocycles, we here in
report the synthesis of a novel series of pyrazoline derivatives
(3ae3j) bearing quinoline tail.
2. Chemistry
The synthesis of novel series of pyrazoline derivatives (3ae3j)
was performed in a manner as outlined in Scheme 1. The cyclization
of chalcones (1ae1j) with 2-(quinolin-8-yloxy) acetohydrazide (2)
under basic condition (aq$NaOH 10%, 1 mL) in 50 mL absolute
Abbreviations:
milligram; mmol, millimole.
* Corresponding author. Tel.: þ91 11 2698 1717/3254; fax: þ91 11 2698 0229.
E-mail address: amir_sumbul@yahoo.co.in (A. Azam).
mg, microgram; mL, microliter; mM, micromole; mL, milliliter; mg,
0223-5234/$ e see front matter Ó 2010 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2010.07.028

4670
F. Hayat et al. / European Journal of Medicinal Chemistry 45 (2010) 4669e4675
N
.
OH
(b)
O
O
N
O
H
CH
3
O
O
R2
+
R
1
CH
3
(c)
(a)
O
N
6'
3'
6
3
O
O
5
5'
4'
R
R
1
2
2
2'
4
NH
2
NH
(1a-1j)
(2)
(d)
Compound
R1
R2
3a
3b
3c
3d
3e
3f
3g
3h
3i
4-Br
4-OCH3
H
4-OCH3
4-CH3
H
4-CH3
H
4-OCH3
2-Cl
N
4-Br
4-Cl
4-Cl
4-Cl
H
H
H
H
O
O
N
N
HX
3j
H
3-Cl
HA
(3a-3j)
HB
R
2
R
1
Reagent and conditions: (a) aq. NaOH, C2H5OH, RT (24 hrs.) (b) Ethyl chloroacetate,
K2CO3, Acetone (c) N2H4.2H2O (d) NaOH, C2H5OH, Reflux 12-15hrs
Scheme 1. General method for the synthesis of pyrazoline derivatives (3ae3j).
ethanol led to the formation of novel series of pyrazoline deriva-
tives. All the compounds were stable in solid state. Melting points
were recorded on KSW melting point apparatus and are uncor-
rected (Fig. 1).
3. Pharmacology
All pyrazoline derivatives (3ae3j) were screened in vitro against
HM1:IMSS strain of E. histolytica by microdilution method [23]. All
the experiments were carried out in triplicate at each concentration
level and repeated thrice. Cytotoxicity of active compounds has
been studied by MTT assay on human breast cancer MCF-7 cell line.
The results of biological activity and cytotoxicity are summarized in
Table 1 and Fig. 2.
3'
4'
5'
2'
N
6'
1'
8'
7'
O
4. Results and discussion
O
4.1. Synthesis
1
2
N
N
HX
5
Synthesis of novel series of pyrazoline derivatives (3ae3j) is
described in this study and their reaction sequence is outlined in
Scheme 1. A series of chalcones (1ae1j) were prepared by base-
catalyzed ClaiseneSchmidt condensation of appropriate
substituted acetophenones and benzaldehydes in good yield (75%e
80%) [24]. The cyclization of chalcones (1ae1j) with 2-(quinolin-8-
yloxy) acetohydrazide (2) in presence of base led to the formation
3
4
HA
HB
R
2
R
1
(3a-3j)
Fig. 1. Structure of pyrazoline derivatives (3ae3j).

F. Hayat et al. / European Journal of Medicinal Chemistry 45 (2010) 4669e4675
4671
Table 1
microdilution method using HM1: IMSS strain of E. histolytica and
their IC50 values are reported in Table 1. The metronidazole was
Novel pyrazoline derivatives (3ae3j), their in vitro antiamoebic activity against
HM1:IMSS strain of E. histolytica and cytotoxicity profile of compounds 3d, 3g, 3h, 3j
and metronidazole.
used as reference drug having IC50 ¼ 1.84
mM in our experiment.
The results were estimated as the percentage of growth inhibition
compared with the untreated controls and plotted as probit values
as a function of the drug concentration. IC50 and 95% confidence
limits were interpolated in the corresponding dose response curve.
The pyrazoline derivatives (3ae3j) showed IC50 values in the range
3'
4'
5'
2'
N
6'
1'
8'
0.05e16.3
compound 3d (IC50 ¼ 0.05
rings with methyl and chloro groups and compound 3h
M) with methoxy substituted and unsubstituted
mM. In terms of structureeactivity relationship,
7'
mM) substituted at C-4 position of phenyl
O
(IC50 ¼ 0.06
m
O
phenyl rings showed excellent antiamoebic activity against the
1
2
N
N
HM1: 1MSS strain of E. histolytica. The cyclized pyrazoline analogs
HX
5
3
3e (IC50 ¼ 0.72
(IC50 ¼ 0.29
phenyl rings also showed good antiamoebic activity and the
M) moderately active than the standard
m
M), 3g (IC50 ¼ 0.31
m
M), 3i (IC50 ¼ 0.71
mM), and 3j
mM) having chloro substituted and unsubstituted
4
HA
HB
compound 3c (IC50 ¼ 1.68
m
R
2
R
1
drug metronidazole. Therefore, out of ten compounds screened in
vitro for antiamoebic activity, four compounds 3d, 3g, 3h and 3j
were more active than the standard drug metronidazole.
(3a-3j)
Compound
R1
R2
Antiamoebic
activity
Cytotoxicity
profile
4.3. Cytotoxicity profile
IC50
7.71
16.3
(
mM)
ꢀ SDa
IC50
(
m
M)
ꢀ SDa
To examine the effect of antiamoebic compounds 3d, 3g, 3h, 3j
and metronidazole on cell proliferation, we ensured their cytotoxicity
on human breast cancer MCF-7 cell line. A subconfluent population of
MCF-7 cells was treated with increasing concentrations of
compounds and the number of viable cells was measured after 48 h
by MTT cell viability assay. The concentration range for all the
3a
3b
3c
3d
3e
3f
3g
3h
4-Br
4-Br
4-Cl
4-Cl
4-Cl
H
H
H
H
H
4-OCH3
H
4-OCH3
4-CH3
H
4-CH3
H
4-OCH3
2-Cl
0.16
0.02
0.04
0.02
0.13
0.09
0.10
0.03
0.08
0.12
0.19
N.D.
N.D.
N.D.
>100
N.D.
N.D.
>100
98.3
N.D.
N.D.
N.D.
0.26
N.D.
N.D.
0.14
0.18
N.D.
0.14
0.28
1.68
0.05
0.72
7.50
0.31
0.06
0.71
0.29
1.84
compounds 3d, 3g, 3h, 3j and metronidazole was 1.56e100
Figure-2 depicts the compounds 3d, 3g, 3h, 3j and metronidazle
exhibited >80% viability at the concentration range of 1.56e50 M.
On increasing the concentration range up to 100 M only compound
mM.
3i
3j
N.D.
>100
>100
3-Cl
m
Metronidazole
m
The compounds with bold font IC50 values are more active than metronidazole.
3g (Viability 55%) and 3h (Viability 49%) showed moderate cytotox-
icity against the human breast cancer MCF-7 cell line. The cytotox-
icity IC50 values along with the standard deviation values of
compounds 3d, 3g, 3h, 3j and metronidazle are given in Table 1.
a
The value obtained in at least three separate assay done in triplicate, N.D. ¼ Not
done, S.D. ¼ Standard deviation.
of novel series of pyrazoline derivatives (3ae3j). All the compounds
were characterized by IR, 1H NMR, 13C NMR and Mass spectral
studies and their data are presented in the experimental section.
5. Conclusion
In summary, novel pyrazoline derivatives (3ae3j) were
synthesized by the cyclization of chalcones (1ae1j) with 2-(qui-
nolin-8-yloxy) acetohydrazide (2) under basic condition. The in
vitro antiamoebic activity was examined using HM1: IMSS strain of
E. histolytica and results showed that out of ten compounds four
4.2. Antiamoebic activity
Preliminary experiments were carried out to determine the in
vitro antiamoebic activity of all the compounds (3ae3j) by
Fig. 2. Cytotoxic effect of compounds 3d, 3g, 3h, 3j and metronidazole on human breast cancer MCF-7 cells as assessed by the MTT dye reduction assay following a 48 h treatment.
Data represent the arithmetic means ꢀ S.D. of at least three independent experiments (n ¼ 3 in triplicates).

4672
F. Hayat et al. / European Journal of Medicinal Chemistry 45 (2010) 4669e4675
compounds 3d, 3g, 3h and 3j exhibited higher antiamoebic activity
than the reference drug metronidazole (IC50 ¼ 1.84 M). The MTT
assay revealed that all the compounds 3d, 3g, 3h, 3j and metroni-
dazole were nontoxic at the concentration range of 1.56e50 M. On
increasing the concentration range up to 100 M, only compound
b
), 7.64e7.58 (m, 4H, AreH), 7.37 (d, 1H, J ¼ 15.6 Hz, H-
a
), 6.96 (d, 2H,
m
J ¼ 8.7 Hz, H-3, H-5), 3.85 (s, 3H, OCH3); 13C NMR (CDCl3)
d
(ppm):
190.18 (C]O), 144.65 (C-b), (135.61, 132.70, 130.02, 128.51, AreH),
122.23 (C-
m
a
), 53.65 (OCH3); FAB-MS (m/z): [Mþ þ 1] 273.
m
3g and 3h showed moderate cytotoxicity against the human breast
cancer MCF-7 cell line.
6.1.4. (2E)-1-(4-Chlorophenyl)-3-(4-methylphenyl) propenone (1d)
Yield: 72%; mp: 153 ꢁC; white crystals; Anal. calc. for
C16H13O2Cl: C 74.85, H 5.10%; found: C 74.69, H 5.04%; IR nmax
(cmꢂ1): 3028 (AreH), 2916 (CeH), 1657 (C]O), 1448 (C]C); 1H
6. Experimental protocol
NMR (CDCl3)
J ¼ 15.6 Hz, H-
H-
d
(ppm): 7.91 (d, 2H, J ¼ 8.4 Hz, H-20, H-60), 7.82 (d, 1H,
All the required chemicals were purchased from Merck and
Aldrich Chemical Company (USA). 2-(Quinolin-8-yloxy) acetohy-
drazide (2) was synthesized by using the method reported in
literature [25]. Precoated aluminium sheets (silica gel 60 F254,
Merck Germany) were used for thin-layer chromatography (TLC)
and spots were visualized under UV light. Elemental analysis was
carried out on CHNS Elementar (Vario EL-III) and the results were
within ꢀ 0.3% of the theoretical values. IR spectra were recorded on
PerkineElmer model 1600 FT-IR RX1 spectrophotometer as KBr
discs. 1H NMR and 13C NMR spectra were recorded on Bruker
Spectrospin DPX 300 MHz and Bruker Spectrospin DPX 75 MHz
spectrometer respectively using CDCl3 as a solvent and trime-
thylsilane (TMS) as an internal standard. Splitting patterns are
designated as follows; s, singlet; d, doublet; m, multiplet. Chemical
shift values are given in ppm. The FAB mass spectra of the
compounds were recorded on JEOL SX 102/DA-6000 mass spec-
trometer using Argon/Xenon 6 kV, 10 mA as the FAB gas and m-
nitro benzyl alcohol (NBA) was used as the matrix.
b
), 7.55e7.48 (m, 4H, AreH), 7.46 (d, 1H, J ¼ 15.6 Hz,
a
), 7.25e7.21 (m, 2H, AreH) 2.39 (s,3H, CH3); 13C NMR (CDCl3)
d
(ppm): 189.27 (C]O), 145.44 (C-b), (139.07, 131.99, 129.92, 128.63,
AreH), 120.53 (C-
a
), 21.54 (methyl); FAB-MS (m/z): [Mþ þ 1] 257.
6.1.5. (2E)-1-(4-Chlorophenyl)-3-phenyl propenone (1e)
Yield: 78%; mp: 67 ꢁC; white crystals. Anal. calc. for C15H11OCl: C
74.23, H 4.57%; found: C 74.12, H 4.45%; IR nmax (cmꢂ1): 3051
(AreH), 2930 (CeH), 1683 (C]O), 1440 (C]C); 1H NMR (CDCl3)
d
(ppm): 7.92 (d, 2H, J ¼ 8.4 Hz, H-20, H-60), 7.83 (d, 1H, J ¼ 15.6 Hz,
H-
H-
b
a
), 7.79e7.53 (m, 4H, H-2, H-6, H-30, H-50), 7.49 (d,1H, J ¼ 15.6 Hz,
), 7.37e6.99 (m, 3H, H-3, H-4, H-5); 13C NMR (CDCl3)
d (ppm):
191.43 (C]O), 143.41 (C-b), (136.07, 134.70, 130.02, 128.51, AreH),
121.42 (C-
a
); FAB-MS (m/z): [Mþ þ 1] 243.
6.1.6. (2E)-3-(4-Methylphenyl)-1-phenyl propenone (1f)
Yield: 76%; mp: 189 ꢁC; light yellow crystals; Anal. calc. for
C16H14O: C 86.45, H 6.35%; found: C 86.31, H 6.24%; IR nmax (cmꢂ1):
3058 (AreH), 2932 (CeH), 1659 (C]O), 1447 (C]C); 1H NMR
6.1. General procedure for the synthesis of substituted chalcones
(1ae1j)
(CDCl3)
d
(ppm): 8.02 (d, 2H, J ¼ 6.9 Hz, H-20, H-60), 7.82 (d, 1H,
J ¼ 15.6 Hz, H-
H-
(ppm): 189.23 (C]O), 144.41 (C-b), (134.70, 130.02, 129.53,128.51,
b
), 7.60e7.49 (m, 4H, AreH), 7.46 (d, 1H, J ¼ 15.6 Hz,
a
), 7.25e7.18 (m, 3H, AreH), 2.39 (s,3H, CH3).13C NMR (CDCl3)
A
mixture of substituted acetophenone (0.01 mol) and
d
substituted benzaldehyde (0.01 mol), and sodium hydroxide (1 mL,
10% aqueous) in 50 mL absolute ethanol was stirred at room
temperature for 24 h. The resulting solid was filtered, washed with
water, dried, and recrystallized from ethanol.
phenyl), 122.52 (C-
a
), 22.45 (methyl); FAB-MS (m/z): [Mþ þ 1] 223.
6.1.7. (2E)-1,3-diphenyl propenone (1g)
Yield: 75%; mp: 57 ꢁC; yellow crystals; Anal. calc. for C15H12O: C
86.51, H, 5.81%; found: C 86.38, H 5.69%; IR nmax (cmꢂ1): 3064 (AreH),
6.1.1. (2E)-1-(4-Bromophenyl)-3-(4-methoxyphenyl) propenone
(1a)
2939 (CeH), 1658 (C]O), 1460 (C]C); 1H NMR (CDCl3)
d
(ppm): 7.81
(m,10H, AreH), 7.74 (d,1H, J ¼ 15 Hz, H-
13C NMR (CDCl3)
128.92, 127.63, AreH), 122.09 (C-
b
), 7.53 (d,1H, J ¼ 15 Hz, H- );
a
Yield: 78%; mp: 67 ꢁC; white crystals; Anal. calc. for C16H13O2Br:
C 60.59, H 4.13%; found: C 60.48, H 4.08%; IR nmax (cmꢂ1): 3036
(AreH), 2933 (CeH), 1676 (C]O), 1442 (C]C); 1H NMR (CDCl3)
d (ppm): 190.49 (C]O),144.78 (C-b), (134.51, 132.72,
a
); FAB-MS (m/z): [Mþ þ 1] 209.
d
(ppm): 7.89 (d, 2H, J ¼ 8.7 Hz, H-20, H-60), 7.81 (d, 1H, J ¼ 15.6 Hz,
6.1.8. (2E)-3-(4-Methoxyphenyl)-1-phenyl propenone (1h)
H-
b
), 7.65e7.59 (m, 4H, AreH), 7.37 (d, 1H, J ¼ 15.6 Hz, H-
a
), 6.95
Yield: 78%; mp: 122 ꢁC; light green crystals; Anal. calc. for
C16H14O2: C 80.65, H 5.92%; found: C 80.51, H 5.81%; IR nmax (cmꢂ1):
3054 (AreH), 2938 (CeH), 1656 (C]O), 1446 (C]C); 1H NMR
(d, 2H, J ¼ 8.7 Hz, H-3, H-5), 3.86 (s, 3H, OCH3); 13C NMR (CDCl3)
d
(ppm): 189.73 (C]O), 144.41 (C-b), (136.07, 134.70, 130.02, 128.51,
AreH), 122.52 (C-
a
), 53.81 (OCH3); FAB-MS (m/z): [Mþ þ 1] 318.
(CDCl3)
d
(ppm): 7.97 (d, 2H, J ¼ 8.4 Hz, H-20, H-60), 7.65 (d, 1H,
J ¼ 15.6 Hz, H-
b
), 7.56e7.44 (m, 4H, AreH), 7.39 (d, 1H, J ¼ 15.6 Hz,
6.1.2. (2E)-1-(4-Bromophenyl)-3-phenyl propenone (1b)
H-a d
), 7.38e7.11(m, 3H, AreH), 3.86 (s, 3H, OCH3); 13C NMR (CDCl3)
Yield: 74%; mp: 163 ꢁC; white crystals; Anal. calc. for C15H11OBr: C
62.74, H 3.86%; found: C 62.63, H 3.75%; IR nmax (cmꢂ1): 3056 (AreH),
(ppm): 191.83 (C]O), 144.41 (C-b), (135.17, 134.70, 132.02, 128.59
AreH), 121.52 (C-
a
), 54.65 (OCH3); FAB-MS (m/z): [Mþ þ 1] 239.
2931 (CeH),1656 (C]O),1446 (C]C); 1H NMR (CDCl3)
d (ppm): 7.89
(d, 2H, J ¼ 8.7 Hz, H-20, H-60), 7.79 (d, 2H, J ¼ 8.1 Hz, H-30, H-50), 7.56
6.1.9. (2E)-3-(2-Chlorophenyl)-1-phenyl propenone (1i)
(d, 1H, J ¼ 15.6 Hz, H-
b
), 7.44e7.38 (m, 2H, AreH), 7.31(1H,
Yield: 74%; mp: 133 ꢁC; light yellow crystals; Anal. calc. for
C15H11OCl: C 74.23, H 4.57%; found: C 74.17, H 4.48%; IR nmax (cmꢂ1):
3060 (AreH), 2931 (CeH), 1662 (C]O), 1465 (C]C); 1H NMR (CDCl3)
J ¼ 15.6 Hz, H-
a
), 7.15e6.86 (m, 3H, AreH); 13C NMR (CDCl3);
d
(ppm): 189.83 (C]O), 145.41 (C-b), (136.07, 134.70, 130.02, 128.51,
AreH), 121.52 (C-
a
); FAB-MS (m/z): [Mþ þ 1] 288.
d
(ppm): 8.20 (d, 1H, J ¼ 5.4 Hz, H-60), 8.15 (d, 1H, J ¼ 5.4 Hz, H-20),
8.01 (d, 1H, J ¼ 15 Hz, H-
b), 7.76e7.30 (m, 8H, AreH, H-a
); 13C NMR
6.1.3. (2E)-1-(4-Chlorophenyl)-3-(4-methoxyphenyl) propenone
(1c)
(CDCl3)
d (ppm): 188.83 (C]O), 143.41 (C-b), (136.98, 135.43, 134.20,
130.02, 128.58, AreH), 123.56 (C-
a
); FAB-MS (m/z): [Mþ þ 1] 243.
Yield: 80%; mp: 94 ꢁC; light green crystals; Anal. calc. for
C16H13O2Cl: C 70.46, H 4.80%; found: C 70.34, H 4.68%; IR nmax (cmꢂ1):
3064 (AreH), 2934 (CeH), 1677 (C]O), 1442 (C]C); 1H NMR (CDCl3)
6.1.10. (2E)-3-(3-Chlorophenyl)-1-phenyl propenone (1j)
Yield: 98%; mp:172 ꢁC; light green crystals; Anal. calc. for C15H11OCl:
C 74.23, H 4.57%; found: C 74.13, H 4.41%; IR nmax (cmꢂ1): 3068 (AreH),
d
(ppm): 7.83 (d, 2H, J ¼ 8.7 Hz, H-20, H-60), 7.81 (d, 1H, J ¼ 15.6 Hz, H-

F. Hayat et al. / European Journal of Medicinal Chemistry 45 (2010) 4669e4675
4673
2913 (CeH),1683(C]O),1466 (C]C); 1HNMR(CDCl3)
d
(ppm): 7.94 (d,
126.76,123.33, 121.30,109.88, quinoline ring and phenyl ring), 65.31
(CH2), 55.27 (OCH3), 55.32 (C-5, pyrazoline), 41.84 (C-4, pyrazo-
line); FAB-MS (m/z): [Mþ þ 1] 472.
2H, J¼ 8.3 Hz, H-20,H-60), 7.65 (d,1H, J¼ 15.6 Hz, H-
b), 7.53e7.37 (m, 5H,
AreH), 7.36(d,1H, J ¼ 15.615.6 HzHz, H-
a C
), 7.31e7.27(m, 2H, AreH); 13
d (ppm): 190.03 (C]O), 142.41 (C-b), (136.71, 134.94,
NMR (CDCl3)
130.17, 128.66 AreH), 123.52 (C-
a
); FAB-MS (m/z): [Mþ þ 1] 243.
6.3.4. 1-(3-(4-Chlorophenyl)-4,5-dihydro-5-p-tolylpyrazol-1-yl)-2-
(quinolin-8- yloxy) ethanone (3d)
6.2. Preparation of 2-(quinolin-8-yloxy) acetohydrazide (2)
Yield: 12%; mp: 132 ꢁC; white solid; Anal. calc. for C27H22N3O2Cl:
C 71.13, H 4.86, N 9.22%; found: C 71.18, H 4.74, N 9.13%; IR nmax
(cmꢂ1): 3034 (AreH), 2927 (CH2), 1682 (C]O), 1594 (C]N), 1440
2-(Quinolin-8-yloxy) acetohydrazide was prepared by a repor-
ted method [25].
(C]C), 1198 (CeN); 1H NMR (CDCl3)
d
(ppm): 8.92 (d, 1H, J ¼ 3.6 Hz,
H-20quinoline ring), 8.10 (d, 1H, J ¼ 8.1 Hz, H-40quinoline ring),
7.71e6.97 (m, 12H, phenyl and quinoline ring), 5.62 [dd, 1H, J ¼ 4.5,
11.7 Hz, Hx (pyrazoline ring)], 5.42 (s, 2H, OCH2), 3.78 [dd,1H, J ¼ 12,
17.7 Hz, HA (pyrazoline ring)], 3.21 [dd, 1H, J ¼ 4.5, 17.7 Hz, HB
6.3. General procedure for the synthesis of pyrazoline derivatives
(3ae3j)
A mixture of the chalcones 1ae1j (10 mmol), 2-(quinolin-8-
yloxy) acetohydrazide 2 (10 mmol) and NaOH (25 mmol) was
refluxed in ethanol (50 mL) for 12e15 h. The contents were reduced
under vacuo, cooled, and poured onto crushed ice and kept for 1 h
at room temperature. The resulting precipitate was collected by
filtration and purified by column chromatography using hex-
ane:ethyl acetate (7:3 v/v) as eluent to yield (3ae3j).
(pyrazoline)], 2.29 (s, 3H, CH3); 13C NMR (CDCl3)
d (ppm): 165.27
(C]O), 154.29 (C-3, pyrazoline ring), (149.23, 140.25, 135.73,
132.03, 128.28, 126.76, 123.33, 121.30, 109.88, quinoline and phenyl
ring), 66.31 (CH2), 55.27 (OCH3), 55.32 (C-5, pyrazoline), 41.51 (C-4,
pyrazoline); FAB-MS (m/z): [Mþ þ 1] 456.
6.3.5. 1-(3-(4-Chlorophenyl)-4,5-dihydro-5-phenylpyrazol-1-yl)-2-
(quinolin-8-yloxy) ethanone (3e)
6.3.1. 1-(3-(4-Bromophenyl)-4,5-dihydro-5-(4-methoxyphenyl)
pyrazol-1-yl)-2-(quinolin-8-yloxy) ethanone (3a)
Yield: 14%; mp: 96 ꢁC; white solid; Anal. calc. for C26H20N3O2Cl: C
70.67, H 8.02, N 9.51%; found: C 70.54, H 8.06, N 9.43%; IR nmax (cmꢂ1):
3087 (AreH), 2924 (CH2), 1678 (C]O), 1592 (C]N), 1432 (C]C), 1241
Yield: 18%; mp: 104 ꢁC; white solid; Anal. calc. for C27H22N3O3Br:
C 62.80, H 4.29, N 8.14%; found: C 62.73, H 4.24, N 8.16%; IR nmax
(cmꢂ1): 3035 (AreH), 2928 (CH2), 1683 (C]O), 1592 (C]N), 1446
(CeN); 1H NMR (CDCl3)
d
(ppm): 8.93 (d, 1H, J ¼ 3.9 Hz, H-20quinoline
ring), 8.11 (d, 1H, J ¼ 8.1 Hz, H-40quinoline ring), 7.79e6.96 (m, 13H,
phenyl and quinoline ring), 5.62 [dd, 1H, J ¼ 4.5,11.7 Hz, Hx (pyrazoline
ring)], 5.43 (s, 2H, OCH2), 3.85 [dd, 1H, J ¼ 12, 18 Hz, HA (pyrazoline)],
3.24 [dd, 1H, J ¼ 4.8, 18 Hz, HB (pyrazoline ring)]; 13C NMR (CDCl3)
(C]C), 1238 (CeN); 1H NMR (CDCl3)
d
(ppm): 8.92 (d, 1H, J ¼ 3.6 Hz,
H-20quinoline ring), 8.10 (d, 1H, J ¼ 8.1 Hz, H-40quinoline ring),
7.64e6.80 (m, 12H, phenyl and quinoline ring), 5.61 [dd, 1H, J ¼ 4.5,
11.7 Hz, Hx (pyrazoline ring)], 5.40 (s, 2H, OCH2), 3.75 [dd, 1H, J ¼ 12,
18 Hz, HA (pyrazoline ring)], 3.21 [dd, 1H, J ¼ 4.5, 17.7 Hz, HB (pyr-
d
(ppm): 165.37 (C]O), 154.49 (C-3, pyrazoline ring), (148.23, 141.35,
135.73, 131.63, 128.28, 127.76, 123.33, 121.30, 108.88, quinoline and
phenyl ring), 65.31 (CH2), 55.35 (C-5, pyrazoline ring), 41.51 (C-4,
pyrazoline ring); FAB-MS (m/z): [Mþ þ 1] 442.
azoline ring)], 3.67 (s, 3H, OCH3); 13C NMR (CDCl3)
d (ppm): 165.88
(C]O), 155.75 (C-3, pyrazoline ring), (148.23, 141.25, 134.73, 132.03,
128.12,,123.53, 121.26, 109.50, quinoline and phenyl ring), 65.91
(CH2), 55.97 (OCH3), 55.29 (C-5, pyrazoline ring), 41.51 (C-4, pyr-
azoline ring); FAB-MS (m/z): [Mþ þ 1] 517.
6.3.6. 1-(4,5-Dihydro-3-phenyl-5-p-tolylpyrazol-1-yl)-2-(quinolin-
8-yloxy)ethanone (3f)
Yield: 12%; mp: 103 ꢁC; white solid; Anal. calc. for C27H23N3O2: C
76.94, H 5.50, N 9.97%; found: C 76.81, H 5.41, N 9.91%; IR nmax (cmꢂ1):
3042 (AreH), 2928 (CH2), 1684 (C]O),1595 (C]N),1434 (C]C),1244
6.3.2. 1-(3-(4-Bromophenyl)-4,5-dihydro-5-phenylpyrazol-1-yl)-2-
(quinolin-8-yloxy) ethanone (3b)
Yield: 15%; mp: 125 ꢁC; white solid; Anal. calc. for C26H20N3O2Br:
C 64.21, H 4.14, N 8.64%; found: C 64.16, H 4.09, N, 8.51%; IR nmax
(cmꢂ1): 3031 (AreH), 2921 (CH2), 1681 (C]O), 1591 (C]N), 1439
(CeN); 1H NMR (CDCl3)
d
(ppm): 8.93 (d,1H, J ¼ 3.9 Hz, H-20quinoline
ring), 8.10 (d, 1H, J ¼ 8.1 Hz, H-40quinoline ring), 7.79e6.98 (m, 13H,
phenyl and quinoline ring), 5.62 [dd, 1H, J ¼ 4.5, 11.7 Hz, Hx (pyr-
azoline ring)], 5.44 (s, 2H, OCH2), 3.82 [dd, 1H, J ¼ 12, 18 Hz, HA
(pyrazoline ring)], 3.26 [dd, 1H, J ¼ 4.8, 18 Hz, HB (pyrazoline ring)],
(C]C), 1229 (CeN); 1H NMR (CDCl3)
d
(ppm): 8.92 (d, 1H, J ¼ 3.7 Hz,
H-20quinoline ring), 8.11 (d, 1H, J ¼ 8.1 Hz, H-40quinoline ring),
7.65e6.97 (m, 13H, phenyl and quinoline ring), 5.66 [dd, 1H, J ¼ 4.5,
11.7 Hz, Hx (pyrazoline ring)], 5.43 (s, 2H, OCH2), 3.81 [dd, 1H, J ¼ 11.7,
17.7 Hz, HA (pyrazoline ring)], 3.24 [dd, 1H, J ¼ 4.8, 17.7 Hz, HB (pyr-
2.29 (s, 3H, CH3); 13C NMR (CDCl3)
d (ppm): 165.42 (C]O),155.02 (C-
3, pyrazoline ring), (149.28, 141.38, 133.73, 130.63, 128.98, 127.36,
123.33, 121.70, 109.88, quinoline and phenyl ring), 66.31 (CH2), 55.33
(C-5, pyrazoline ring), 41.65 (C-4, pyrazoline ring); FAB-MS (m/z):
[Mþ þ 1] 422.
azoline ring)]; 13C NMR (CDCl3)
d (ppm): 165.82 (C]O), 155.69 (C-3,
pyrazoline), (148.25, 140.25, 133.73, 132.03, 127.18, 126.62, 123.93,
121.36, 109.58, quinoline and phenyl ring), 65.31 (CH2), 55.32 (C-5,
pyrazoline), 41.84 (C-4, pyrazoline); FAB-MS (m/z): [Mþ þ 1] 487.
6.3.7. 1-(4,5-Dihydro-3,5-diphenylpyrazol-1-yl)-2-(quinolin-8-
yloxy)ethanone (3g)
6.3.3. 1-(3-(4-Chlorophenyl)-4,5-dihydro-5-(4-methoxyphenyl)
pyrazol-1-yl)-2-(quinolin-8-yloxy) ethanone (3c)
Yield: 13%; mp: 115 ꢁC; white solid; Anal. calc. for C26H21N3O2: C
76.64, H 5.19, N 9.97%; found: C 76.53, H 5.14, N 9.89%; IR nmax (cmꢂ1):
3034 (AreH), 2928 (CH2), 1676 (C]O), 1591 (C]N), 1466 (C]C), 1123
Yield: 8%; mp: 110 ꢁC; white solid; Anal. calc. for C27H22N3O2Cl:
C 68.71, H 4.70, N 8.90%; found: C 68.62, H 4.61, N 8.82%; IR nmax
(cmꢂ1): 3036 (AreH), 2934 (CH2), 1677 (C]O), 1593 (C]N), 1442
(CeN); 1H NMR (CDCl3)
d
(ppm): 8.92 (d, 1H, J ¼ 3.6 Hz, H-20quinoline
ring), 8.10 (d, 1H, J ¼ 8.1 Hz, H-40quinoline ring), 7.79e6.99 (m, 14H,
phenyl and quinoline ring), 5.66 [dd, 1H, J ¼ 5.1, 11.7 Hz, Hx (pyrazoline
ring)], 5.43 (s, 2H, OCH2), 3.84 [dd, 1H, J ¼ 12, 18 Hz, HA (pyrazoline
ring)], 3.28 [dd, 1H, J ¼ 4.8, 17.7 Hz, HB (pyrazoline ring)]; 13C NMR
(C]C), 1180 (CeN); 1H NMR (CDCl3)
d
(ppm): 8.92 (d, 1H, J ¼ 3.7 Hz,
quinoline ring), 8.10 (d, 1H, J ¼ 8.1 Hz, quinoline ring), 7.71e6.80 (m,
12H, phenyl and quinoline ring), 5.61 [dd, 1H, J ¼ 4.8, 11.7 Hz, Hx
(pyrazoline ring)], 5.46 (s, 2H, OCH2), 3.78 [dd, 1H, J ¼ 11.7, 17.4 Hz,
HA (pyrazoline ring)], 3.22 [dd, 1H, J ¼ 4.8, 17.7 Hz, HB(pyrazoline
(CDCl3) d (ppm): 168.47 (C]O), 155.89 (C-3, pyrazoline ring), (149.83,
141.35, 134.63, 131.63, 127.68, 127.76, 123.33, 120.34, 109.18, quinoline
and phenyl ring), 67.31 (CH2), 55.45 (C-5, pyrazoline ring), 41.21 (C-4,
pyrazoline ring); FAB-MS (m/z): [Mþ þ 1] 408.
ring)], 3.68 (s, 3H, OCH3); 13C NMR (CDCl3)
d (ppm): 165.98 (C]O),
155.29 (C-3, pyrazoline ring), (149.21, 141.25, 134.73, 132.03,128.28,

4674
F. Hayat et al. / European Journal of Medicinal Chemistry 45 (2010) 4669e4675
6.3.8. 1-(4, 5-Dihydro-5-(4-methoxyphenyl)-3-phenylpyrazol-1-
yl)-2-(quinolin-8-yloxy) ethanone (3h)
using trypan blue exclusion to confirm the viability. The suspension
was diluted to 105 organism/mL byadding fresh mediumand 170
L of
this suspension was added to the test and control wells in the plate so
that the wells were completely filled (total volume, 340 L). An inoc-
m
Yield: 8%; mp: 98 ꢁC; white solid; Anal. calc. for C27H23N3O3: C,
74.12, H 5.30, N 9.60%; found: C 74.14, H 5.22, N 9.51%; IR nmax (cmꢂ1):
3038 (AreH), 2926 (CH2), 1674 (C]O), 1593 (C]N),1441 (C]C),1185
m
ulum of 1.7 ꢃ104 organisms/well waschosen sothatconfluent, but not
excessive growth, took place in control wells. Plates were sealed and
gassed for 10 min with nitrogen before incubation at 37 ꢁC for 72 h.
After incubation, the growth of amoeba in the plate was checked with
a low power microscope. The culture medium was removed by
inverting the plate and shaking gently. Plate was then immediately
washed with sodium chloride solution (0.9%) at 37 ꢁC. This procedure
was completed quickly and the plate was not allowed to cool in order
topreventthedetachmentofamoebae. Theplatewasallowedtodryat
room temperature and the amoebaewere fixed with chilled methanol
for 15 min and when dried, stained with (0.5%) aqueous eosin for
15 min. The stained plate was washed once with tap water, then twice
(CeN); 1H NMR (CDCl3)
d
(ppm): 8.93 (d,1H, J ¼ 3.7 Hz, H-20quinoline
ring), 8.12 (d,1H, J ¼ 8.1 Hz, H-40quinoline ring), 7.79e7.06 (m, 13H,
phenyl and quinoline ring), 5.62 [dd, 1H, J ¼ 5.1, 11.7 HZ, Hx (pyr-
azoline ring)], 5.42 (s, 2H, OCH2), 3.83 [dd, 1H, J ¼ 12,18 Hz, HA
(pyrazoline ring)], 3.26 [dd, 1H, J ¼ 4.8, 17.7 Hz, HB (pyrazoline ring)];
13C NMR (CDCl3)
d (ppm): 165.37 (C]O), 154.49 (C-3, pyrazoline
ring), (148.23, 141.35, 135.73, 131.63, 128.28, 127.76, 123.33, 121.30,
108.88 quinoline and phenyl ring), 65.31 (CH2), 57.80 (OCH3), 55.35
(C-5, pyrazoline ring), 41.52 (C-4, pyrazoline ring); FAB-MS (m/z):
[Mþ þ 1] 438.
6.3.9. 1-(5-(2-Chlorophenyl)-4,5-dihydro-3-phenylpyrazol-1-yl)-2-
(quinolin-8-yloxy) ethanone (3i)
with distilled water and allowed to dry. A 200 mL portion of 0.1 N
sodium hydroxide solution was added to each well to dissolve the
protein and release the dye. The optical density of the resulting solu-
tion in each well was determined at 490 nmwith a microplate reader.
The % inhibition of amoebal growth was calculated from the optical
densities of the control and test wells and plotted against the loga-
rithm of the dose of the drug tested. Linear regression analysis was
used to determine the best fitting line from which the IC50 value was
Yield: 12%; mp: 117 ꢁC; white solid; Anal. calc. for C26H20N3O2Cl:
C 70.67, H 4.56, N 9.51%; found: C 70.59, H 4.46, N 9.45%; IR nmax
(cmꢂ1): 3043 (AreH), 2927 (CH2), 1682 (C]O), 1594 (C]N), 1440
(C]C), 1218 (CeN); 1H NMR (CDCl3)
d
(ppm): 8.93 (d, 1H, J ¼ 3.8 Hz,
H-20quinoline ring), 8.11 (d, 1H, J ¼ 8.1 Hz, H-40quinoline ring),
7.77e7.07 (m, 13H, phenyl and quinoline ring), 5.62 [dd, 1H, J ¼ 5.1,
11.7 Hz, Hx (pyrazoline ring)], 5.49 (s, 2H, OCH2), 3.88 [dd,1H, J ¼ 12,
18 Hz, HA (pyrazoline ring)], 3.16 [dd, 1H, J ¼ 4.8, 17.7 Hz, HB (pyr-
found. The IC50 values in mM are reported in Table 1.
azoline ring)]; 13C NMR (CDCl3)
d (ppm): 166.31 (C]O),155.69 (C-3,
6.5. MTT assay
pyrazoline ring), (148.63, 140.15, 134.76, 132.83, 128.88, 127.76,
123.33, 121.30, 109.43, quinoline and phenyl ring), 66.31 (CH2),
55.25 (C-5, pyrazoline ring), 41.59 (C-4, pyrazoline ring); FAB-MS
(m/z): [Mþ þ 1] 442.
The human breast cancer MCF-7 cells used in this study were
purchased from National Center for Cell Science (NCCS), Pune, India.
The cells were cultured and maintained as monolayer in Dulbecco’s
modified Eagle’s medium (Sigma) supplemented with 10% of fetal
calf serum (Sigma), antibiotics: 100 IU/mL of penicillin (Sigma) and
6.3.10. 1-(5-(3-Chlorophenyl)-4,5-dihydro-3-phenylpyrazol-1-yl)-
2-(quinolin-8-yloxy) ethanone (3j)
100 mg/mL of streptomycin (Sigma). All cells were cultured in T-75
Yield: 16%; mp: 146 ꢁC; white solid; Anal. calc. for C26H20N3O2Cl: C
70.67, H 4.56, N 9.51%; found: C 70.56, H 4.49, N 9.42%; IR nmax (cmꢂ1):
3068 (AreH), 2913 (CH2), 1683 (C]O), 1596 (C]N),1466 (C]C), 1239
corning culture flasks at 37 ꢁC in the 100% humidity atmosphere and
5% of CO2 [29]. Only viable cells wereused in the assay. Exponentially
growing cells were plated at 1.2 ꢃ 104 cells per well into 96-well
plates and incubated for 48 h before the addition of drugs to achieve
the maximum confluency of the cells. Stock solutions were prepared
by dissolving the compounds in 20% (v/v) DMSO and further diluted
with fresh complete medium to achieve 1 M concentration. The
growth-inhibitory effects of the compounds were measured using
standard tetrazolium MTTassay. After 48 h of incubation at 37 ꢁC, the
(CeN); 1H NMR (CDCl3)
d
(ppm): 8.94 (d, 1H, J ¼ 3.8 Hz, H-20quinoline
ring), 8.10 (d, 1H, J ¼ 8.1 Hz, H-40quinoline ring), 7.79e7.01 (m, 13H,
phenyl and quinoline ring), 5.62 [dd, 1H, J ¼ 4.5, 11.7 Hz, Hx (pyr-
azoline ring)], 5.44 (s, 2H, OCH2), 3.85 [dd, 1H, J ¼ 12, 18 Hz, HA
(pyrazoline ring)], 3.25 [dd, 1H, J ¼ 4.8, 17.7 Hz, HB (pyrazoline ring)];
13C NMR (CDCl3)
d (ppm): 165.24 (C]O), 155.69 (C-3, pyrazoline
ring), (149.27, 141.34, 134.73, 132.63, 128.18, 127.76, 123.44, 121.50,
108.68, quinoline and phenyl ring), 66.31 (CH2), 55.15 (C-5, pyrazoline
ring), 41.57 (C-4, pyrazoline ring); FAB-MS (m/z): [Mþ þ 1] 442.
medium was removed and 25 ml of MTT reagent (5 mg/mL) in serum
free medium was added to each well. The plates were incubated at
37 ꢁC for 4 h. At the end of the incubation period, the medium was
removed and pure DMSO 100
mL was added to each well. The
6.4. In vitro antiamoebic assay
metabolized MTT product dissolved in DMSO was quantified by
measuring the absorbance at 570 nm on an ELISA plate reader
(Labsystems Multiskan RC, Helsinki, Finland) with a reference
wavelength of 655 nm. All assays were performed in triplicate and
repeated thrice. Percent viability was defined as the relative absor-
bance of treated versus untreated control cells.
All the compounds (3ae3j) were screened in vitro for antiamoebic
activity against HM1: IMSS strain of E. histolytica by microdilution
method [23]. E. histolytica trophozoites were cultured in wells of 96-
well microtiter plate by using Diamond TYIS-33 growth medium [26].
The test compounds (1 mg) were dissolved in DMSO (40 mL) at which
level no inhibition of amoeba occurs [27,28]. The stock solutions of the
compounds were freshly prepared before use at a concentration of
1 mg/mL. Two-fold serial dilutions were made in the wells of 96-well
microtiter plate (costar). Each test includes metronidazole as a stan-
dard amoebicidal drug, control wells (culture medium plus amoebae)
and a blank (culture medium only). All the experiments were carried
out in triplicate at each concentration level and repeated thrice. The
amoeba suspensionwas prepared from a confluent culture by pouring
off the medium at 37 ꢁC and adding 5 mL of fresh medium, chilling the
culture tube on ice to detach the organisms from the side of the flask.
The number of amoeba/ml was estimated with a hemocytometer,
Acknowledgments
This work was supported by Council of Scientific and Industrial
Research (grant # 01(2278)/08/EMR-II New Delhi, India). One of us
(F.H) is thankful to the University Grant commission (UGC), India
for the financial support.
References
[1] R. Haque, C.D. Huston, M. Hughes, E. Houpt, W.A. Petri Jr., N. Engl. J. Med. 348
(2003) 1565e1573.

F. Hayat et al. / European Journal of Medicinal Chemistry 45 (2010) 4669e4675
4675
[2] S.L. Stanley Jr., Lancet 361 (2003) 1025e1034.
[3] J. Blessman, I.K.M. Ali, P.A.T. Nu, B.T. Dinh, T.Q.N. Viet, A.L. Van, et al., J. Clin.
Microbiol. 41 (2003) 4745e4750.
[4] R. Haque, P. Duggal, I.M. Ali, M.B. Hossain, D. Mondal, R.B. Sack, et al., J. Infect.
Dis. 186 (2002) 547e552.
[5] C.D. Wells, M. Arguedas, Southampt. Med. J. 97 (2004) 673e682.
[6] J. Blessmann, H.D. Binh, D.M. Hung, E. Tannich, G. Burchard, Trop. Med. Int.
Health 8 (2003) 1030e1034.
[17] A.J. Hee, K. Hye-Min, J.S. Ho, K.S. Kyu, K.K. Rok, R.S. Dal, et al., Bioorg. Med.
Chem. Lett. 14 (2004) 4461e4465.
[18] Y.R. Prasad, A.L. Rao, L. Prasoona, K. Murali, P.R. Kumar, Bioorg. Med. Chem.
Lett. 15 (2005) 5030e5034.
[19] M.V.R. Reddy, V.K. Billa, V.R. Pallela, M.R. Mallireddigari, R. Boominathan,
J.L. Gabriel, et al., Bioorg. Med. Chem. 16 (2008) 3907e3916.
[20] P.M.S. Chauhan, S.K. Srivastava, Curr. Med. Chem. 8 (2001) 1535e1542.
[21] K.H. Chikhalia, M.J. Patel, D.B. Vashi, Arkivoc xiii (2008) 189e197.
[22] M. Azad, M.A. Munawar, H.L. Siddiqui, J. Appl. Sci. 7 (2007) 2485e2489.
[23] C.W. Wright, M.J. O’Neill, J.D. Phillipson, D.C. Warhurst, Antimicrob. Agents
Chemother. 32 (1988) 1725e1729.
[7] W.A. Petri, Parasitology 19 (2003) 523e526.
[8] F.A. el-Nahas, M.I. el-Ashmawy, Basic Clin. Pharmacol. Toxicol. 94 (2004)
226e231.
[9] V. Purohit, K.A. Basu, Chem. Res. Toxicol. 13 (2000) 673e692.
[10] P. Abboud, V. Lemee, G. Gargala, P. Brasseur, J.J. Ballet, F. Borsa-Lebas, et al.,
Clin. Infect. Dis. 32 (2001) 1792e1794.
[24] J.N. Dominguez, C. Leon, J. Rodrigues, N.G. Dominguez, J. Gut, P.J. Rosenthal,
Eur. J. Med. Chem. 44 (2009) 1457e1462.
[25] M. Ahmed, R. Sharma, D.P. Nagda, J.L. Jat, G.L. Talesara, Arkivoc xi (2006)
66e75.
[26] L.S. Diamond, D.R. Harlow, C.C.R. Cunnick, Trans. R. Soc. Trop. Med. Hyg.
72 (1978) 431e432.
[11] W. Petri, Trends Parasitol. 19 (2003) 523e526.
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
[12] Z. Ratkovic, Z.D. Juranic, T. Stanojkovic, D. Manojlovic, R.D. Vukicevic,
ꢀ
N. Radulovic, et al., Bioorg. Chem. 38 (2010) 26e32.
[13] M.S. Karthikeyan, B.S. Holla, N.S. Kumari, Eur. J. Med. Chem. 42 (2007) 30e36.
[14] B.S. Holla, P.M. Akberali, M.K. Shivananda, Farmaco 55 (2000) 256e263.
[15] E. Bansal, V.K. Srivastava, A. Kumar, Eur. J. Med. Chem. 36 (2001) 81e92.
[16] F. Manna, F. Chimenti, R. Fioravanti, A. Bolasco, D. Secci, P. Chimenti, et al.,
Bioorg. Med. Chem. Lett. 15 (2005) 4632e4635.
[27] F.D. Gillin, D.S. Reiner, M. Suffness, Antimicrob. Agents Chemother. 22 (1982)
342e345.
[28] A.T. Keene, A. Harris, J.D. Phillipson, D.C. Warhurst, Planta Med. 52 (1986) 278e284.
ꢁ
[29] F. Gümüs, Ö. Algül, G. Eren, H. Eroglu, N. Diril, S. Gür, et al., Eur. J. Med. Chem.
38 (2003) 473e480.