Synthesis and cytotoxicity study of pyrazoline derivatives of methoxy substituted naphthyl chalcones

Article abstract of DOI:10.1007/s11164-012-0718-3

2-Acetyl naphthalene reacts with various methoxy substituted benzaldehyde in the presence of 10 % sodium hydroxide solution giving functionalized chalcones. The synthesized chalcones when further reacted with hydrazine hydrate in the presence of acetic ac

Full text of DOI:10.1007/s11164-012-0718-3

Res Chem Intermed
DOI 10.1007/s11164-012-0718-3
Synthesis and cytotoxicity study of pyrazoline
derivatives of methoxy substituted naphthyl chalcones
•
K. R. Ethiraj P. Nithya V. Krishnakumar
•
•
•
A. Jesil Mathew F. Nawaz Khan
Received: 7 June 2012 / Accepted: 7 July 2012
Ó Springer Science+Business Media B.V. 2012
Abstract 2-Acetyl naphthalene reacts with various methoxy substituted benzal-
dehyde in the presence of 10 % sodium hydroxide solution giving functionalized
chalcones. The synthesized chalcones when further reacted with hydrazine hydrate
in the presence of acetic acid afforded N-acetyl pyrazolines. All the synthesized
1
products were confirmed by various spectral data such as FTIR, H NMR, 13C
NMR, and HRMS studies. All the synthesized compounds were screened for
cytotoxicity against various cell lines.
Keywords Methoxy substituted chalcones ꢀ Pyrazolines and Cytotoxicity studies
Electronic supplementary material The online version of this article (doi:
10.1007/s11164-012-0718-3) contains supplementary material, which is available to authorized users.
K. R. Ethiraj
Pharmaceutical Chemistry Division, School of Advanced Sciences, VIT University,
Vellore 632 014, Tamil Nadu, India
P. Nithya
Chemistry Division, School of Advanced Sciences, VIT University - Chennai Campus,
Chennai 600 127, Tamil Nadu, India
V. Krishnakumar ꢀ F. Nawaz Khan (&)
Organic Chemistry Division, Organic and Medicinal Chemistry Research Laboratory,
School of Advanced Sciences, VIT University, Vellore 632 014, India
e-mail: nawaz_f@yahoo.co.in
A. Jesil Mathew
Department of Pharmaceutical Biotechnology, Manipal College of Pharmaceutical Sciences,
Manipal University, Manipal, Udupi, Karnataka, India
123

K. R. Ethiraj et al.
Introduction
The chalcones or enones possessing methoxy substitutents have demonstrated their
potential as effective pharmaceutical agents and in many applications [1, 2], and it has
been observed that methoxy groups present in the chalcones are good acceptors which
facilitate hydrogen bonding, while the 2-naphthyl ring is electron rich and can form p-
stacking which play vital roles in orientating the inhibitors within the active site, as well
as significantly contributing to the biological activity observed for these inhibitors [3].
Similarly, naproxen and nabumetone are effective COX (cyclooxygenase) inhibitors,
both the drugs possessing naphthyl and methoxy groups in the core structure. Based on
the this importance, the present study envisioned the synthesis and pharmaceutical
evaluation of methoxy and naphthyl ring incorporated chalcones. The enones or
chalcones provide a bifunctional site for 1-3 dinucleophile affording the synthesis of
various heterocycles like pyrazolines [2–6], isoxazole, thiazine and oxazine derivatives
[7]. Pyrazolines are important nitrogen-containing heterocyclic compounds, and are
reported to have anti-microbial [8–10], anti-inflammatory [11–13] anti-cancer [14–16],
anti-oxidant [17], anti-viral [18], anti-depressant [19], anti-diabetic, anti-mycobacterial
[20, 21], and anti-malarialproperties[22, 23]. Pyrazolines arefoundinapplicationssuch
as dyestuff, analytical reagents, and in the agricultural industry. Therefore, the
pyrazoline moiety has a predominant role in medicinal chemistry since it is part of many
scaffolds which show an impressive array of activity. Moreover, pyrazolines play an
important role in heterocyclic chemistry and are used extensively in organic chemistry.
Pyrazoline derivatives exhibit growth inhibitory properties on several cancer cell
lines [24] and also act as effective inhibitors of heptosyltransferase [25]. Some of the
pyrazolines were effective in inhibiting the accumulation of prion protein [26], the
abnormal protease-resistant form. When pyrazolones were part of a tricyclic system, it
is expected to possess a cytotoxicity profile by inhibiting tubulin polymerization [27].
The colchicine binding site in tubulin is a better target for many small molecules
like combretastatin A-4 [28]. Various structure activity studies proved that
chalcones have better binding characteristics in the colchicine binding site in
tubulin [29]. Since the tubulin binding activity is more predominant in chalcones
than in cis configuration, it is ideal to lock the stereochemistry to cis orientation.
This is achieved by fusing the carbon–carbon double bond in the bridge with five-
membered or six-membered rings[30–40]. Pyrazolines should possess a twisted
geometry for better activity and improved biological solubility [30].
The chemistry and cytotoxicity characteristics of various substituted pyrazolines
have been investigated worldwide in recent years to synthesize novel pyrazolines
from easily available starting materials and to evaluate their possible cytotoxicity
profiles. Therefore, in the view of above facts, we synthesized some 3-(naphthalen-
2-yl)-5-phenyl-1H-pyrazolines. All the derivatives were confirmed by spectral study
and evaluated for their cytotoxicity profile against various cell lines.
Results and discussion
The synthetic route for the pyrazolines are shown in Scheme 1. Compound 1 is
2-acetyl naphthalene on reaction with various methoxy substituted benzaldehydes
123

Synthesis and cytotoxicity study of pyrazoline derivatives
2a–g in ethanol in the presence of 10 % sodium hydroxide solution for 3 h.
Chalcones, 1-(naphthalen-2-yl)-3-phenylprop-2-en-1-one, 3a–g were obtained and
purified by recrystallisation from methanol. The acetylated pyrazolines, 4a–g, were
obtained from chalcones 3a–g by refluxed with hydrazine hydrate in acetic acid for
3 h. The reaction was monitored by thin layer chromatography and melting points
were determined by an open capillary tube method. All the synthesized scaffolds
were characterized by IR, 1H NMR, 13C NMR and HRMS spectroscopic techniques
(Table 1).
The N-acetyl pyrazoline, 1-acetyl-5-(3,5-dimethoxyphenyl)-3-(2-naphthyl)-4,5-
dihydro-1H-pyrazole (5f) carbonyl peak appears at 1,664 cm-1 in IR spectra. The
two methoxy methyl groups appeared in downfield at d 3.75 ppm and the N-acetyl
methyl group appeared in at d 2.48 ppm. The pyrazoline ring methyne (CH) split
into quartet d 5.54 ppm by adjacent methylene of the pyrazoline ring. The two
methylene protons appeared at d 3.25 and 3.82 ppm. The methoxy substituted three
aromatic protons appeared as multiplet at d 6.33–6.40 ppm and all the remaining
aromatic protons appeared at d 7.49–8.05 ppm. The HRMS of compound 5f showed
a molecular ion peak M? in the positive mode. The molecular ion peak of 5f was
observed at m/z 374.7421.
Biological activity
The cytotoxicity of the synthesized pyrazolines towards different cell lines, viz.,
HCT-15 (human colon carcinoma), HeLa (cervical carcinoma), and A549 (lung
adenocarcinoma), were determined by MTT {[3-(4,5-dimethylthiazol-2-yl)-2,5-
diphenyltetrazolium bromide]} assay. The formazan produced during the MTT
assay formed by the viable cells was solubilized by addition of 100 mL isopropanol.
O
R1
CHO
R2
R3
R5
R4
R1
R2
O
a
+
R5
R4
R3
3 (a-g)
1
2 (a-g)
b
Ac
N
N
R1
R2
R3
R5
R4
4 (a-g)
Scheme 1 Synthesis of substituted N-acetyl pyrazoles. Reagents and conditions: a NaOH, ethanol,
3–4 h. b N2H4ꢀH2O, acetic acid, ethanol, reflux, 3 h
123

K. R. Ethiraj et al.
Table 1 Pyrazolines synthesized
O
N
N
R
R
1
4
R
R
2
3
R
5
Compound
R1
R2
R3
R4
R5
Time (h)
Yield (%)
4a
4b
4c
4d
4e
4f
OCH3
OCH3
H
H
H
OCH3
H
H
3
82
59
81
81
58
89
79
OCH3
OCH3
H
OCH3
OCH3
OCH3
OCH3
H
H
4
OCH3
H
H
3
OCH3
OCH3
H
H
3.5
4
H
OCH3
OCH3
H
H
OCH3
H
H
3
4g
OCH3
OCH3
OCH3
3.75
The absorbance was recorded at 540 nm in a micro plate reader (Bio-tek, ELx 800).
The % cytotoxicity was calculated using the formula
ꢀ
ꢁ
ðAbstest ꢂ AbsBlankÞ ꢂ ðAbscontrol ꢂ AbsBlank
Þ
% cytotoxicity ¼ 100 ꢁ
ðAbscontrol ꢂ AbsBlank
Þ
Table 2 % cytotoxicity of pyrazolines 4a–g against various cell lines
Conc. tested (lg/mL)
4a
4b
4c
4d
4e
4f
4g
% cytotoxicity in HCT-15 (human colon carcinoma) cells
12.5
25
63.98
70.60
69.84
78.45
56.28
59.56
72.51
85.22
64.97
99.92
54.53
70.83
87.43
93.53
46.92
84.16
96.50
98.86
53.62
67.40
72.89
74.41
0.64
0.69
20.79
29.40
50
101.07
100.76
100
% cytotoxicity in HeLa (cervical carcinoma) cells
12.5
25
40.34
40.95
45.54
47.26
10.21
18.37
27.53
53.83
42.65
66.09
14.97
30.27
43.57
66.95
60.02
98.79
99.09
98.88
46.50
51.97
53.69
60.75
0
3.17
0.11
6.68
50
100.17
100.35
100
% cytotoxicity in A549 (lung adenocarcinoma) cells
12.5
25
45.27
45.30
46.62
63.22
27.10
33.20
65.98
61.77
42.96
93.93
97.74
96.42
0.87
24.39
54.95
78.70
27.92
74.27
98.88
98.93
40.37
48.73
78.82
85.59
0
0
50
4.75
15.83
100
123

Synthesis and cytotoxicity study of pyrazoline derivatives
Table 3 IC50 values
compounds against various cell
lines
Compounds
HCT-15 (lM)
HeLa (lM)
A549 (lM)
4a
4b
4c
4d
4e
4f
0.0213
0.0272
0.0197
0.0320
0.0309
0.0320
\100.00
0.2225
0.0370
0.2134
0.0247
0.0400
\100.00
0.1736
0.0865
0.0346
0.1200
0.0432
0.0667
4g
\100.00
\100.00
All pyrazolines, 4a–g, of different concentrations were tested for the cytotoxic
potential against all three cell lines and the results are shown in Table 2. The
minimum concentration required for 50 % cytotoxicity and inhibitory concentration
required for 50 % cytotoxicity (IC50) values are set out in Table 3.
Against HCT15, all the compounds showed significant activity and compounds
4c and 4a showed IC50 values of 0.0197 and 0.0213 lM, respectively. Compounds
4a, 4d, 4e and 4f also exhibited better activity. Compounds 4d and 4a showed
significant cytotoxicity activity against A549 with IC50 values of 0.1250 and
0.1736 lM, respectively, and all other compounds except 4g showed comparable
inhibition of cell growth. Pyrazoline, 4e, had a better IC50 value of 0.0247 lM
against HeLa, and 4c and 4f showed significant effects with IC50 values of 0.0370
and 0.0400 lM, respectively. Compound 4g did not show any activity against any
of the cells employed for the study below 100 lg/mL.
Conclusion
In summary, we have described synthesis and biological evaluations of pyrazolines
derived from methoxy substituted chalcones, which possess cytotoxicity against
various cell lines for cervical cancer (HeLa), colon carcinoma (HCT15), and
adenocarcinoma (A549). All the tested compounds showed potential activities
against colon carcinoma (HCT15). Among them, compound 4c, 1-acetyl-5-(2-
naphthyl)-3-(3,4,5-trimethoxyphenyl)-4,5-dihydro-1H-pyrazole, was found to be
most effective with IC50 values of 0.197, 0.0370, and 0.0346 lM against HCT15,
A549, and HeLa, respectively.
Experimental section
Materials and methods
Melting points were recorded with an open capillary tube and corrected with
1
benzoic acid. Infrared spectra were recorded on a Perkin-Elmer 1720 FT IR. H
NMR spectra were recorded on a Bruker AC 400 MHz, spectrometer using tetra
methyl silane (TMS) as an internal standard in CDCl3. The HRMS mass spectra
were recorded on a JEOLSX 102/DA-6000 mass spectrometer.
123

K. R. Ethiraj et al.
Chromatographic separations were done using silica gel (60–120 mesh). Thin
layer chromatography (TLC) was performed using glass plates coated with silica gel
G, and the spots visualization were done by iodine vapor. Chemicals were
purchased from Sigma-Aldrich, India and Sd-Fine chemicals India and were used
without further purification. All the solvents were purchased from Sd-Fine
chemicals, India, and used without further purification.
Synthesis of 1-acetyl-5-(2,5-dimethoxyphenyl)-3-(2-naphthyl)-4,5-dihydro-
1H-pyrazole
The synthetic pathway of acetylated pyrazolines from methoxy substituted
chalcones is depicted in Scheme 1. The sodium hydroxide catalyzed Claisen–
Schmidt condensation of equimolar mixture of 2-acetylnaphthalene, 1, and various
methoxy-substituted benzaldehydes, 2a–g under stirring for 3 h in ethanol and kept
in an ice bath overnight afforded the respective chalcones, 3a–g, in excellent yields.
The transformation was clean and efficient.
The reactions were carried out by dissolving the equimolar quantity of
appropriate ketones and aldehydes in a minimum amount of ethanol and stirred
in the presence of 10 % NaOH under suitable temperature for appropriate time
periods. The reaction after completion (as monitored by thin layer chromatography,
using EtOAc: Pet. Ether solvent system) was kept aside overnight at room
temperature for the precipitation of crude chalcones, which were filtered off and
recrystallized from methanol.
All the chalcones were treated with hydrazine hydrate in hot glacial acetic acid to
afford 1-acetyl-3,5-diaryl-2-pyrazolines in good yields. It was done by refluxing the
desired chalcones (5 mmol) with hydrazine hydrate (25 mmol) in hot acetic acid
(30 mL) for 3 h, and the completion of reaction was confirmed by TLC using the
mobile phase ethyl acetate and hexane in various proportions (1:9, 2:8, 3:7). After
completion of the reaction, the reaction mixture was poured over crushed ice
(250 mL) and the precipitate was collected by vacuum filtration. The product was
washed with water, dried, and recrystallized from methanol.
1-Acetyl-5-(2, 5-dimethoxyphenyl)-3-(2-naphthyl)-4,5-dihydro-1H-pyrazole, (4a)
Yellow solid, mp 113–115 °C; IR (KBr) 1,661 (CO), cm-1 1H NMR (400 MHz,
CDCl3) d 2.51 (s, 3H), 3.13–3.19 (d, J = 4.6 Hz, 1H), 3.71 (s, 3H), 3.79 (s, 3H),
5.85–5.89 (q, J = 4.6 Hz, 1H), 6.62–6.62 (d, J = 2.9 Hz, 1H), 6.71–6.74 (dd,
J = 5.8 Hz, J = 3.0 Hz, 1H), 6.81–6.83 (d, J = 9.2 Hz, 1H), 7.49–7.52 (m, 2H),
7.48–7.8 (m, 3H), 7.906 (s, 1H), 8.04–8.07 (dd, J = 7.0 Hz, J = 1.6 Hz, 1H)
HRMS [EI, M?] calcd for C23H22N2O3 m/z 374.4324, found 374.3861.
1-Acetyl-5-(2,3,4-trimethoxyphenyl)-3-(2-naphthyl)-4,5-dihydro-1H-pyrazole, (4b)
Pale yellow, mp 136–138 °C; IR (KBr) 1,664 (CO), cm-1 1H NMR (400 MHz,
CDCl3) d 2.47 (s, 3H), 3.21–3.23 (d, J = 4.6 Hz, 1H), 3.77 (s, 3H), 3.84 (s, 3H),
3.93 (s, 3H), 5.72–5.76 (q, J = 4.8 Hz, 1H), 6.58–6.60 (d, J = 8.6 Hz, 1H),
123

Synthesis and cytotoxicity study of pyrazoline derivatives
6.81–6.84 (d, J = 8.8 Hz, 1H), 7.50–7.53 (m, 2H), 7.82–7.87 (m, 3H), 7.93 (s, 1H),
8.07–8.09 (dd, J = 6.8 Hz, J = 1.6 Hz, 1H), HRMS [EI, M?] calcd for
C24H21N2O4 m/z 404.4584, found 404.3401.
1-Acetyl-5-(2-naphthyl)-3-(3,4,5-trimethoxyphenyl)-4,5-dihydro-1H-pyrazole, (4c)
Light yellow, mp 129–131 °C; IR (KBr) 1,655 (CO), cm-1 1H NMR (400 MHz,
CDCl3) d 2.48 (s, 3H), 3.28–3.33 (q, J = 4.8 Hz, 1H), 3.80–3.89 (m, 9H), 4.00 (s,
1H), 5.55–5.59 (q, J = 4.8 Hz, 1H), 6.54 (s, 2H), 7.50–7.56 (m, 2H), 7.83–7.89 (m,
3H), 7.94 (s, 1H), 8.07–8.09 (dd, J = 6.8 Hz, J = 1.6 Hz, 1H), HRMS [EI, M?]
calcd for C24H24N2O4 m/z 404.4584, found 404.0028.
1-Acetyl-5-(2,4-dimethoxyphenyl)-3-(2-naphthyl)-4,5-dihydro-1H-pyrazole, (4d)
Yellow solid, mp 109–111 °C; IR (KBr) 1,663 (CO), cm-1 1H NMR (400 MHz,
CDCl3) d 2.49 (s, 3H), 3.62–3.87 (m, 7H), 5.78–5.82 (q, J = 4.5 Hz, 1H), 6.39–6.42
(dd, J = 6.0 Hz, J = 2.3 Hz, 1H), 6.46–6.47 (d, J = 2.2 Hz, 1H), 6.96–6.98 (d,
J = 8.4 Hz, ‘1H), 7.46–7.58 (m, 2H), 7.79–7.97 (m, 5H), 8.05–8.08 (d, J = 7.0 Hz,
1H), HRMS [EI, M?] calcd for C23H22N2O3 m/z 374.4324, found 374.7421.
1-Acetyl-5-(2,4,5-trimethoxyphenyl)-3-(2-naphthyl)-4,5-dihydro-1H-pyrazole, (4e)
Light brown, mp 152–155 °C; IR (KBr) 1,660 (CO), cm-1 1H NMR (400 MHz,
CDCl3) d 2.48 (s, 3H), 3.18–3.19 (q, J = 4.8 Hz, 1H), 3.76–4.00 (m, 10H),
5.77–5.81 (q, J = 4.8 Hz, 1H), 7.48–7.55 (m, 2H), 7.81–7.90 (m, 3H), 7.93 (s, ‘1H),
8.06–8.09 (dd, J = 6.8 Hz, J = 1.6 Hz, 1H), HRMS [EI, M?] calcd for
C24H24N2O4 m/z 404.4584, found 404.2773.
1-Acetyl-5-(3,5-dimethoxyphenyl)-3-(2-naphthyl)-4,5-dihydro-1H-pyrazole, (4f)
Off white, mp 113–115 °C; IR (KBr) 1,664 (CO), cm-1 1H NMR (400 MHz,
CDCl3) d 2.48 (s, 3H), 3.25–3.31 (d, J = 4.6 Hz, 1H), 3.75–3.87 (m, 7H), 5.54–5.58
(q, J = 4.6 Hz, 1H), 6.33–6.40 (m, 3H), 7.49–7.55 (m, 2H), 7.82–7.87 (m, 3H),
7.91 (s, 1H), 8.05–8.07 (dd, J = 7.1 Hz, J = 1.6 Hz, 1H) MS [EI, M?] calcd for
C23H22N2O3 m/z 374.4324, found 374.7421.
Determination of cytotoxicity
Cytotoxic effect of synthesized acetylated pyrazolines were assessed using 3-(4,
5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay [31].
Exponentially growing cells were seeded in triplicate in 96-well plates at a
concentration of 5 9 103 cells/well [100 lL of Dulbecco’s modified Eagle’s
medium (DMEM), supplemented with 10 % fetal bovine serum (FBS) as medium].
After 24 h, upon attachment of the cells, the medium was replaced with medium
containing gradient concentrations of synthesized compounds. For this purpose, test
compounds were dissolved in 0.1 % dimethyl sulfoxide (DMSO), and diluted with
123

K. R. Ethiraj et al.
the medium. The cells were then exposed to different concentrations of the
pyrazolines ranging from 0.1 to 100 lg/mL and incubated for 72 h. Cells in the
control wells received the same volume of medium containing 0.1 % DMSO. After
72 h, the medium was flicked off and cell cultures were incubated with 100 lL of
MTT reagent (2 mg/mL) for 4 h at 37 °C.
Acknowledgments The authors express their sincere gratitude towards the management of VIT
University, Vellore for their generous support and great encouragement in carrying out this work. The
authors greatly acknowledge STIC-CUSAT, Cochin, for NMR analysis.
References
1. N.J. Lawrence, R.P. Patterson, L.L. Ooi, D. Cook, S. Duckic, Bioorg. Med. Chem. 16, 5844 (2006)
2. Z. Nowakowska, Eur. J. Med. Chem. 42, 125 (2007)
3. A. Mascarello, L.D. Chiaradia, J. Vernal, A. Villarino, R.V.C. Guido, P. Perizzolo, V. Poirier,
D. Wonge, P.G.A. Martins, R.J. Nunes, R.A. Yunes, A.D. Andricopulo, Y.A. Gay, H. Terenzi,
Bioorg. Med. Chem. 18, 7383 (2010)
4. A. Levai, Chem. Heterocycl. Comp. 33, 647 (1997)
5. I.G. Rathish, K. Javed, S. Ahmad, S. Bano, M.S. Alam, K.K. Pillai, S. Singh, V. Bagchi, Bioorg.
Med. Chem. Lett. 19, 255 (2009)
6. M. A. Rahman, CSJ. 29 (2011)
7. R. Kalirajan, S.U. Sivakumar, S. Jubie, B. Gowramma, B. Suresh, J. Chem. Tech. Res. 1, 27 (2009)
8. M.S. Karthikeyan, B.S. Holla, N.S. Kumari, Eur. J. Med. Chem. 42, 30 (2007)
9. E.M. Sharshira, N.M.M. Hamada, Molecules 16, 7736 (2011)
10. P.M. Sivakumar, S. Ganesan, P. Veluchamy, M. Doble, Chem. Biol. Drug Des. 76, 407 (2010)
11. S.M. Sondhi, S. Kumar, N. Kumar, P. Roy, Med. Chem. Res. 1 (2011)
12. M.V. Reddy, V.K. Billa, V.R. Pallela, M.R. Mallireddigari, R. Boominathan, J.L. Gabriel,
E.P. Reddy, Bioorg. Med. Chem. Lett. 16, 3907 (2008)
13. P.M. Sivakumar, S. Prabhu Seenivasan, V. Kumar, M. Doble, Bioorg. Med. Chem. Lett. 20, 3169
(2010)
14. E. Nassar, J. Am. Sci. 6 (2010)
15. M.S.M. Al-Saadi, Saudi Pharm. J. 16, 135 (2008)
16. N.B. Ahasan, M.R. Islam, Bang. J. Phar. 2, 81 (2008)
17. B.P. Bandgar, S.S. Gawande, R.G. Bodade, N.M. Gawande, C.N. Khobragade, Bioorg. Med. Chem.
17, 8168 (2009)
18. R. Ramajayam, K.P. Tan, H.G. Liu, P.H. Liang, Bioorg. Med. Chem. 18, 7849 (2010)
19. Y.R. Prasad, A. Lakshmana Rao, L. Prasoona, K. Murali, P. Ravi Kumar, Bioorg. Med. Chem. Lett.
15, 5030 (2005)
20. M.A. Rahman, A.A. Siddiqui, Int. J. Pharm. Sci. Drug Res. 2 (2010)
21. P.E. Almeida da Silva, D.F. Ramos, H.G. Bonacorso, A.I. De la Iglesia, M.R. Oliveira, T. Coelho,
J. Navarini, H.R. Morbidoni, N. Zanatta, M.A.P. Martins, Int. J. Antimicrob. 32, 139 (2008)
22. S. Kumar, S. Bawa, S. Drabu, R. Kumar, H. Gupta, Recent Pat. Antiinfect. Drug Discov. 4, 154
(2009)
23. B.N. Acharya, D. Saraswat, M. Tiwari, A.K. Shrivastava, R. Ghorpade, S. Bapna, M.P. Kaushik, Eur.
J. Med. Chem. 45, 430 (2010)
24. M. Johnson, B. Younglove, L. Lee, R. LeBlanc, H. Holt Jr, P. Hills, H. Mackay, T. Brown,
S.L. Mooberry, M. Lee, Bioorg. Med. Chem. Lett. 17, 5897 (2007)
ˇ
25. B. Burjaa, T.C. Zovkob, S. Tomicc, T. Jelusicb, M. Kocevara, S. Polanca, M. Osmak Bioorg, Med.
Chem. 18, 2375 (2010)
26. A. Kimata, H. Nakagawa, R. Ohyama, T. Fukuuchi, T.S. Ohta, T. Suzuki, N. Miyata, J. Med. Chem.
50, 5053 (2007)
27. M.A. Aziz1, O.M. Aly, S.S. Khan, K. Mukherjee, S. Bane, Arch Pharm. (2012). doi:
10.1002/ardp.201100471
123

Synthesis and cytotoxicity study of pyrazoline derivatives
28. S. Ducki, R. Forrest, J.A. Hadfield, A. Kendall, N.J. Lawrence, A.T. McGown, D. Rennison, Bioorg.
Med. Chem. Lett. 8, 1051 (1998)
29. S. Ducki, G. Mackenzie, B. Greedy, S. Armitage, J.F.D. Chabert, E. Bennett, J. Nettles, J.P. Snyder,
N.J. Lawrence, Bioorg. Med. Chem. 17, 7711 (2009)
30. N.J. Lawrence, R.P. Patterson, L.L. Ooi, D. Cook, S. Ducki, Bioorg. Med. Chem. Lett. 16, 5844
(2006)
31. T. Mosmann, J. Immunol. Methods 65, 55 (1983)
32. F.N. Khan, R. Jayakumar, C.N. Pillai, Tetrahedron Lett. 43, 6807 (2002)
33. K. Prabakaran, P. Manivel, F.N. Khan, Tetrahedron Lett. 51, 4340 (2010)
34. K. Prabakaran, F.N. Khan, J.S. Jin, Tetrahedron Lett. 52, 2566 (2011)
35. S.M. Roopan, F.N. Khan, B.K. Mandal, Tetrahedron Lett. 51, 2309 (2010)
36. N.T. Patil, F. N. Khan, Y. Yamamoto, Tetrahedron Lett. 45, 8497 (2004)
37. F. N. Khan, R. Jayakumar, C.N. Pillai, J. Mol. Cat. A. 195, 139 (2003)
38. P. Manivel, S. Mohana Roopan, F. N. Khan, J. Chil. Chem. Soc. 53, 1609 (2008)
39. V.R. Hathwar, P. Manivel, F. N. Khan, T.N. Guru Row, Acta Cryst. E63, o3707 (2007)
40. V.R. Hathwar, P. Manivel, F. N. Khan, T.N. Guru Row, Acta Cryst. E63, o3708 (2007)
123