International Journal of PharmTech Research
CODEN (USA): IJPRIF
ISSN : 0974-4304
Vol. 3, No.2, pp 707-718,
April-June 2011
Synthesis, Characterization and Antiproliferative
Activity of Some Novel
2-(substitutedphenyl)-5-methyl-3-(pyridin-4-yl)1,3-thiazolidin-4-ones
G. Nagalakshmi*, T.K. Maity and B.C. Maiti
Division of Medicinal and Pharmaceutical Chemistry, Department of Pharmaceutical
Technology, Jadavpur University, Kolkata-700 032, West Bengal, India
*Corres. author: nagalakshmipharma@gmail.com
Phone: +919007818897
Abstract: 1,3-Thiazolidin-4-one is a versatile lead molecule for designing potential bioactive agents. In the present
study, pyridin-4-amine (1) on condensation with different aromatic aldehydes (2a-g) in presence of catalytic amount of
concentrated hydrochloric acid in absolute ethanol yield N-[(Z)-(substitutedphenyl)methylidene]pyridin-4-amine (3a-g),
which on cyclisation with 2-sulfanylpropanoic acid in dry 1,4-dioxane in presence of anhydrous zinc chloride afford the
corresponding 2-(substitutedphenyl)-5-methyl-3-(pyridin-4-yl)-1,3-thiazolidin-4-ones (4a-g). The structure of the newly
synthesized compounds (3a-g) and (4a-g) were confirmed by IR and 1H NMR spectral data. All the newly synthesized
1,3-thiazolidin-4-one analogues (4a-g) at various concentrations (10, 20, 50, 100 and 200 mcg/ml) have been evaluated
for in vitro cytotoxicity against Dalton’s ascites lymphoma (DAL) cancer cell line by trypan blue exclusion method.
Compound 2-(2,4-dichlorophenyl)-5-methyl-3-(pyridin-4-yl)-1,3-thiazolidin-4-one (4b) and 2-(4-bromophenyl)-5methyl-3-(pyridin-4-yl)-1,3-thiazolidin-4-one (4g) inhibited 100% and 78% DAL tumor cells at 100 mcg/ml and 100%
and 89% at 200 mcg/ml concentration, whereas standard drug doxorubicin exhibit 100% DAL inhibition at a
concentration of 100 mcg/ml. From the above study, compounds 4b and 4g which showed better results (> 50%
inhibition) at lowest concentration were selected for in vitro testing of antiproliferative activity against L929 lung
fibroblast cell line by using MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay method. In the
antiproliferative assay, compound 4b (IC50 = 15.3 μg/ml) and compound 4g (IC50 = 26.5 μg/ml) showed the highest
cytotoxic activity against L929 cells.
Key words: pyridin-4-amine, 1,3-thiazolidin-4-one, Schiff’s base, 2-sulfanylpropanoic acid, antitumor activity,
cytotoxicity, antiproliferative activity, DAL cells, MTT assay.
Introduction
Cancer is the second leading cause of mortality in
developed countries and developing countries as well1.
Two major concerns with currently available
anticancer drugs are their inability to discriminate
between normal and tumor cells and hence unpleasant
drug toxicities and development of resistance due to
expression of drug transporters. Hence, targeting of
proliferative pathways resulting in cell death via
apoptosis or prevention of cell division via cell cycle
arrest, are considered effective strategies for fighting
this disease.
Therefore, a more reasonable approach would be to
synthesize novel compounds which are effective
against cancer while at the same time exhibiting
minimal toxicity to normal cellular functions.
1,3-Thiazolidin-4-one derivatives have been found to
exhibit diverse biological activities such as analgesic2,
anti-inflammatory2,3,
antiproliferative4,
antiangio
5
6
genic , anti-HIV , in vitro anti-Toxoplasma gondii
G. Nagalakshmi et al /Int.J. PharmTech Res.2011,3(2)
activity7, antimicrobial7,8, antimycobacterial9, anti malarial10,
trypanocidal11,
antischistosomal12,
13
14
anticonvulsant ,
antihistaminic ,
anti-cyclooxygenases (COX-1 and COX-2)15, antidiabetic16,
antiarrhythmic17 and antihypertensive properties18.
Pyridine derivatives have been reported to possess a
wide range of biological activities such as antiviral19,
antitubercular20,
anticancer21,
antioxidant22,
22,23
24
cytotoxic , antimitotic ,
antiproliferative25,
inhibition of ribonucleotide reductase26, kinetic spindle
protein27 topoisomerase I and II28, nitric oxide
synthases (NOS)29 and hence used in the treatment of
Alzheimer’s disease30.
Schiff’s bases are well known for versatile
pharmacological activities31 such as antimicrobial,
antifungal, antiviral, analgesic, anti-inflammatory,
radical scavenging, antioxidative, antiulcer, antitumor,
cytotoxic31,
antiproliferative32
and
anti-HIV33
activities.
To search for more specific and novel 1,3-thiazolidin4-one analogues with a wide therapeutic window and a
cytoselective anticancer activity, we synthesized 2-(4substitutedphenyl)-5-methyl-3-(pyridin-4-yl)-1,3thiazolidin-4-ones and evaluate them for their in vitro
antitumor activity against Dalton’s ascites lymphoma
(DAL) cells by trypan blue exclusion method and their
antiproliferative activity against L929 lung fibroblast
cell line by MTT assay method.
Experimental
Chemistry:
Pyridin-4-amine,
4-chlorobenzaldehyde,
2,4dichlorobenzaldehyde,
2-fluorobenzaldehyde,
4fluorobenzaldehyde,
3-nitrobenzaldehyde,
4nitrobenzaldehyde and 4-bromobenzaldehyde and 2sulfanylpropanoic acid, were commercially obtained
from Aldrich (Milwaukee, WI) and dry 1,4-dioxane,
anhydrous
zinc
chloride,
dimethylformamide,
chloroform, concentrated hydrochloric acid and silica
gel-G, were purchased from Merck (Mumbai) and
were used without further purification. Melting points
were determined in open capillary tubes using Veego
melting point apparatus (Model: VMP-DS) and are
uncorrected. The purity of the compounds was
checked by thin layer chromatography (TLC) on silica
gel-G plates of 0.5 mm thickness using Chloroform:
Methanol: Formic acid (10:2:0.2 v/v) and Benzene:
Chloroform (1:1 v/v) as a solvent system and the spots
being visualized under iodine vapours. Concentration
of the solution after the reaction completion involved
the use of a rotary evaporator (Eyela, Japan) operating
under reduced pressure. Infrared (IR) spectra were
recorded on a Jasco FTIR-4100 spectrophotometer
(Jasco Ltd, Tokyo, Japan) using KBr pellet disc
708
technique in the range of 4000-400 cm-1. 1H NMR
spectra were recorded on a Bruker DPX 300 (operating
at 300 MHz) NMR spectrometer using CDCl3 and
DMSO-d6 as solvent and TMS as internal standard
(chemical shifts in δ, ppm). Spin multiplets are given
as s (singlet), br s (broad singlet), d (doublet), t
(triplet), q (quartet) and m (multiplet).
Synthesis of N-[(Z)-(substitutedphenyl) methyli dene]pyridin-4-amine (3a-g):
A mixture of pyridin-4-amine (1) (0.01 mol) and
different aromatic aldehydes (2a-g) (0.01 mol) (4chlorobenzaldehyde (2a), 2,4-dichlorobenzaldehyde
(2b), 2-fluorobenzaldehyde (2c), 4-fluorobenzaldehyde
(2d), 3-nitrobenzaldehyde (2e), 4-nitrobenzaldehyde
(2f) and 4-bromobenzaldehyde (2g)) dissolved in
absolute ethanol (20 ml) in presence of catalytic
amount of conc. hydrochloric acid (0.5 ml) was
refluxed for 5-6 h. The progress of the reaction was
monitored by TLC using Chloroform: Methanol:
Formic acid (10:2:0.2 v/v) as eluents. After the
completion of the reaction, the reaction mixture was
cooled, concentrated under rotary vacuum. Then the
resulting residue was poured into crushed ice and the
product separated was filtered, washed with cold
water, dried and crystallized from chloroform.
Adopting the above procedure seven different schiff’s
bases (3a-g) was synthesized. Percentage yield,
melting point and Rf value of the synthesized
compound (3a-g) were determined and presented in
Table 1.
Synthesis of 2-(substitutedphenyl)-5-methyl-3(pyridin-4-yl)-1,3-thiazolidin-4-one (4a-g):
A
mixture
of
N-[(Z)-(substitutedphenyl)
methylidene]pyridin-4-amine (3a-g) (0.01 mol), 2sulfanylpropanoic acid (0.015 mol) and anhydrous zinc
chloride (0.5 g) in dry 1,4-dioxane (30 ml) was
refluxed for 10-12 h. The progress of the reaction was
monitored by TLC using Benzene: Chloroform (1:1
v/v) as eluents. After the completion of TLC, 1,4dioxane was removed under reduced pressure. The
final residue obtained was poured into crushed ice and
the separated solid was neutralized by adding 10%
sodium bicarbonate solution, for the removal of
unreacted 2-sulfanylpropanoic acid. The neutralized
solid product was filtered, washed with cold water,
dried and crystallized from DMF. Adopting the above
procedure seven different 1,3-thiazolidin-4-one
analogues (4a-g) was synthesized. Percentage yield,
melting point and Rf value of the synthesized
compound (4a-g) were determined and presented in
Table 1.
G. Nagalakshmi et al /Int.J. PharmTech Res.2011,3(2)
709
Scheme 1: Synthetic route for the preparation of novel 2-(substitutedphenyl)-5-methyl-3-(pyridin-4-yl)-1,3thiazolidin-4-ones (4a-g)
O
N
+
R
H
NH2
( 2a - g )
(1)
Abs. C 2H5OH
Conc. HCl
N
N
R
H2O
+
(3a-g)
HS
H3C
Compound
R
O
OH
Anhyd. ZnCl 2
Dry 1,4 -cDioxane d
b
a
H C
4-Cl 3 2,4-(Cl)2
S
O
2-F
4-F
N
R
N
(4a-g)
+
e
f
g
3-NO2
4-NO2
4-Br
H 2O
G. Nagalakshmi et al /Int.J. PharmTech Res.2011,3(2)
710
Table 1: Physical data of N-[(Z)-(substitutedphenyl)methylidene]pyridin-4-amine (3a-g) and 2(substitutedphenyl)-5-methyl-3-(pyridin-4-yl)-1,3-thiazolidin-4-ones (4a-g)
Compound
Mol. Formula/
a
Yield (%)
M.p. (˚C)
Rf
Mol. weight
3a
C12H9ClN2/216.67
72.7 (1.58 g)
81.8 - 83.8
0.50
3b
C12H8Cl2N2/251.11
84.1 (2.11 g)
79.2 - 80.9
0.56
3c
C12H9FN2/200.21
62.5 (1.25 g)
73.9 - 75.9
0.52
3d
C12H9FN2/200.21
69.4 (1.39 g)
82.2 - 83.9
0.49
3e
C12H9N3O2/227.22
75.7 (1.72 g)
67.4 - 68.9
0.44
3f
C12H9N3O2/227.22
86.4 (1.96 g)
96.2 - 97.5
0.63
3g
C12H9BrN2/261.12
81.2 (2.12 g)
94.2 - 95.2
0.65
4a
C15H13ClN2OS/304.79
64.5 (0.49 g)
122.1 - 124.2
0.84
4b
C15H12Cl2N2OS/339.24
70.2 (0.60 g)
132 - 134
0.82
4c
C15H13FN2OS/288.34
54.1 (0.39 g)
114 - 116
0.79
4d
C15H13FN2OS/288.34
60.3 (0.44 g)
127.3 - 129.1
0.75
4e
C15H13N3O3S/315.35
63.6 (0.50 g)
109.2 - 111.4
0.63
4f
C15H13N3O3S/315.35
74.5 (0.59 g)
146 - 148
0.85
4g
C15H13BrN2OS/349.25
71.0 (0.62 g)
138 - 140
0.89
Chloroform: Methanol: Formic acid (10:2:0.2 v/v) for compound (3a-g) and Benzene: Chloroform (1:1 v/v)
for compound (4a-g)
a
N-[(Z)-(4-chlorophenyl)methylidene]pyridin-4amine (3a):
IR (KBr, cm-1): 3141.47 (aromatic C-H), 1602.56
(C=N), 815.742, 711.604 (C-Cl), 1602.56, 1521.56
(C=N, C=C ring stretch), 898.666, 815.742, 711.604
(out-of-plane ring C-H bend), 1315.21, 1213.01,
1078.98 (In-plane ring C-H bend); 1H NMR (DMSOd6, δ ppm): 7.286-7.593 (m, 8H, Ar-H, PyH), 8.079 (s,
1H, N=CH-Ar).
N-[(Z)-(2,4-dichlorophenyl)methylidene]pyridin-4amine (3b):
IR (KBr, cm-1): 3147.26, 3081.69, 3023.84 (aromatic
C-H), 1686.44 (C=N), 854.311, 820.563, 754.031 (CCl), 1686.44, 1583.27, 1462.74 (C=N, C=C ring
stretch), 1375.96, 1247.72, 1195.65, 1131.05, 1096.33,
1051.01 (In-plane ring C-H bend); 1H NMR (CDCl3, δ
ppm): 7.270-7.633 (m, 7H, Ar-H, PyH), 8.263 (s, 1H,
N=CH-Ar).
N-[(Z)-(2-fluorophenyl)methylidene]pyridin-4amine (3c):
IR (KBr, cm-1): 3144.37, 3027.69 (aromatic C-H),
1603.52 (C=N), 1313.29, 1220.72, 1153.22, 1059.69
(C-F), 1603.52, 1522.52 (C=N, C=C ring stretch),
900.594, 809.956, 755.959 (out-of-plane ring C-H
bend); 1H NMR (DMSO-d6, δ ppm): 6.707 (br s, 2H,
Ar-H), 7.200-7.415 (m, 4H, Ar-H, PyH), 7.590-7.634
(m, 1H, PyH), 8.097 (br s, 2H, N=CH-Ar, PyH).
N-[(Z)-(4-fluorophenyl)methylidene]pyridin-4amine (3d):
IR (KBr, cm-1): 3144.37, 3027.69 (aromatic C-H),
1603.52 (C=N), 1313.29, 1220.72, 1154.19, 1059.69
(C-F), 1603.52, 1522.52 (C=N, C=C ring stretch),
899.63, 809.956, 755.959 (out-of-plane ring C-H
bend); 1H NMR (DMSO-d6, δ ppm): 6.704-6.723 (d,
2H, Ar-H), 7.192-7.453 (m, 4H, Ar-H, PyH), 7.5877.633 (m, 1H, PyH), 8.090-8.108 (d, 2H, N=CH-Ar,
PyH).
N-[(Z)-(3-nitrophenyl)methylidene]pyridin-4-amine
(3e):
IR (KBr, cm-1): 3068.02 (aromatic C-H), 1615.90
(C=N), 1582.56, 1534.23 (asymmetric (ArNO2)
(N=O)2), 1352.37, 1275.33 (symmetric (ArNO2)
(N=O)2), 811.24 (C-N, ArNO2), 1615.90, 1582.56,
1534.23, 1471.71, 1446.15, 1399.03 (C=N, C=C ring
stretch), 933.21, 917.82, 811.24, 729.42, 677.58 (outof-plane ring C-H bend), 1202.58, 1101.74, 1076.51,
1008.18 (In-plane ring C-H bend); 1H NMR (CDCl3, δ
ppm): 7.769-7.822 (m, 4H, Ar-H), 8.245-8.270 (m,
G. Nagalakshmi et al /Int.J. PharmTech Res.2011,3(2)
2H, PyH), 8.489-8.519 (m, 2H, PyH), 8.725 (s, 1H,
N=CH-Ar).
N-[(Z)-(4-nitrophenyl)methylidene]pyridin-4-amine
(3f):
IR (KBr, cm-1): 1518.67 (asymmetric (ArNO2)
(N=O)2), 1372.1, 1341.25, 1273.75 (symmetric
(ArNO2) (N=O)2), 860.096 (C-N, ArNO2), 2981.41
(aromatic C-H), 1597.73 (C=N), 1597.73, 1518.67,
1460.81, 1405.85 (C=N, C=C ring stretch), 913.129,
860.096, 771.387, 693.284 (out-of-plane ring C-H
bend); 1H NMR (DMSO-d6, δ ppm): 8.078-8.240 (m,
7H, Ar-H, PyH), 8.390 (s, 1H, PyH), 8.416 (s, 1H,
N=CH-Ar).
N-[(Z)-(4-bromophenyl)methylidene]pyridin-4amine (3g):
IR (KBr, cm-1): 3136.65 (aromatic C-H), 1601.59
(C=N), 529.364 (C-Br), 1601.59, 1520.6 (C=N, C=C
ring stretch), 897.701, 812.849 (out-of-plane ring C-H
bend), 1314.25, 1212.04, 1071.26 (In-plane ring C-H
bend); 1H NMR (CDCl3, δ ppm): 6.442-6.589 (m, 3H,
Ar-H), 7.360-7.387 (m, 2H, Ar-H, PyH), 7.535-7.590
(m, 2H, PyH), 8.262 (s, 2H, N=CH-Ar, PyH).
2-(4-chlorophenyl)-5-methyl-3-(pyridin-4-yl)-1,3thiazolidin-4-one (4a):
IR (KBr, cm-1): 2921.63 (methyl C-H, γas CH3),
2853.17 (methyl C-H, γs CH3), 1701.87 (C=O,
thiazolidin-4-one), 1402 (C-N, tertiary aromatic
amine), 1488.78 (methyl C-H bend, δas CH3), 2921.63
(aromatic C-H), 1627.63, 1488.78, 1402 (C=N, C=C
ring stretch), 1264.11, 1091.51, 1015.34 (In-plane ring
C-H bend), 828.277 (C-Cl); 1H NMR (CDCl3, δ ppm):
7.021-7.422 (m, 8H, Ar-H, PyH), 2.970 (s, 1H, N-CHAr), 3.533-3.641 (m, 1H, CH-CH3), 1.254-1.414 (m,
3H, CH-CH3).
2-(2,4-dichlorophenyl)-5-methyl-3-(pyridin-4-yl)1,3-thiazolidin-4-one (4b):
IR (KBr, cm-1): 1702.84 (C=O, thiazolidin-4-one),
1401.03 (C-N, tertiary aromatic amine), 2921.63
(methyl C-H, γas CH3), 2853.17 (methyl C-H, γs CH3),
1488.78 (methyl C-H bend, δas CH3), 2921.63
(aromatic C-H), 1637.27, 1488.78, 1401.03 (C=N,
C=C ring stretch), 1266.04, 1091.51, 1010.52 (Inplane ring C-H bend), 827.312 (C-Cl); 1H NMR
(CDCl3, δ ppm): 7.020-7.422 (m, 8H, Ar-H, PyH),
2.969 (s, 1H, N-CH-Ar), 3.577-3.641 (m, 1H, CHCH3), 1.254-1.724 (m, 3H, CH-CH3).
2-(2-fluorophenyl)-5-methyl-3-(pyridin-4-yl)-1,3thiazolidin-4-one (4c):
IR (KBr, cm-1): 2921.63 (methyl C-H, γas CH3),
2853.17 (methyl C-H, γs CH3), 1702.84 (C=O,
thiazolidin-4-one), 1401.03 (C-N, tertiary aromatic
amine), 1489.74 (methyl C-H bend, δas CH3), 2921.63
711
(aromatic C-H), 1613.16, 1489.74, 1401.03 (C=N,
C=C ring stretch), 1401.03, 1267, 1090.55, 1015.34
(C-F), 827.312 (out-of-plane ring C-H bend); 1H NMR
(CDCl3, δ ppm): 6.975-7.423 (m, 8H, Ar-H, PyH),
2.969 (s, 1H, N-CH-Ar), 3.576-3.641 (m, 1H, CHCH3), 1.254-1.730 (m, 3H, CH-CH3).
2-(4-fluorophenyl)-5-methyl-3-(pyridin-4-yl)-1,3thiazolidin-4-one (4d):
IR (KBr, cm-1): 2979.56 (methyl C-H, γas CH3),
1714.35 (C=O, thiazolidin-4-one), 1366.58, 1342.65
(C-N, tertiary aromatic amine), 2979.56 (aromatic CH), 1644, 1601.71, 1525.42, 1461.32, 1410.52 (C=N,
C=C ring stretch), 1461.32, 1410.52, 1366.58,
1342.65, 1273.58, 1172.36, 1101.08, 1012.31 (C-F),
771.99, 720.25, 690.30 (C-S), 1461.32 (methyl C-H
bend, δas CH3), 1366.58 (methyl C-H bend, δs CH3),
913.57, 858.42, 771.99, 720.25, 690.30 (out-of-plane
ring C-H bend); 1H NMR (CDCl3, δ ppm): 7.081-7.412
(m, 8H, Ar-H, PyH), 2.968 (s, 1H, N-CH-Ar), 3.4913.722 (m, 1H, CH-CH3), 1.254-1.412 (m, 3H, CHCH3).
5-methyl-2-(3-nitrophenyl)-3-(pyridin-4-yl)-1,3thiazolidin-4-one (4e):
IR (KBr, cm-1): 2980.45 (methyl C-H, γas CH3),
2920.66 (methyl C-H, γs CH3), 1715.37 (C=O,
thiazolidin-4-one), 1405.85 (C-N, tertiary aromatic
amine), 1460.81 (methyl C-H bend, δas CH3), 2980.45
(aromatic C-H), 1599.66, 1460.81, 1405.85 (C=N,
C=C ring stretch), 862.025, 773.315, 694.248 (out-ofplane ring C-H bend), 1273.75, 1168.65, 1105.01,
1017.27 (In-plane ring C-H bend), 773.315, 694.248
(C-S), 1599.66 (asymmetric (ArNO2) (N=O)2),
1273.75 (symmetric (ArNO2) (N=O)2), 862.025 (C-N,
ArNO2); 1H NMR (CDCl3, δ ppm): 8.183-8.403 (m,
8H, Ar-H, PyH), 4.378-4.473 (m, 2H, N-CH-Ar, CHCH3), 1.402-1.462 (m, 3H, CH-CH3).
5-methyl-2-(4-nitrophenyl)-3-(pyridin-4-yl)-1,3thiazolidin-4-one (4f):
IR (KBr, cm-1): 2982.37 (methyl C-H, γas CH3),
1714.41 (C=O, thiazolidin-4-one), 1404.89 (C-N,
tertiary aromatic amine), 2924.52 (methyl C-H, γs
CH3), 1461.78 (methyl C-H bend, δas CH3), 2982.37
(aromatic C-H), 1600.63, 1519.63, 1461.78, 1404.89
(C=N, C=C ring stretch), 860.096, 772.351, 693.284
(out-of-plane ring C-H bend), 1273.75, 1168.65,
1105.01, 1017.27 (In-plane ring C-H bend), 772.351,
693.284 (C-S), 1519.63 (asymmetric (ArNO2)
(N=O)2), 1273.75 (symmetric (ArNO2) (N=O)2),
860.096 (C-N, ArNO2); 1H NMR (CDCl3, δ ppm):
8.149-8.403 (m, 8H, Ar-H, PyH), 4.378-4.474 (m, 2H,
N-CH-Ar, CH-CH3), 1.401-1.462 (m, 3H, CH-CH3).
G. Nagalakshmi et al /Int.J. PharmTech Res.2011,3(2)
2-(4-bromophenyl)-5-methyl-3-(pyridin-4-yl)-1,3thiazolidin-4-one (4g):
IR (KBr, cm-1): 3140.68 (aromatic C-H), 2974.25
(methyl C-H, γas CH3), 1702.06 (C=O, thiazolidin-4one), 1335.63, 1316.96 (C-N, tertiary aromatic amine),
1485.96 (methyl C-H bend, δas CH3), 1393.91 (methyl
C-H bend, δs CH3), 1601.68, 1526.06, 1485.96,
1429.94 (C=N, C=C ring stretch), 665.41, 631.11,
614.47, 585.28, 526.77 (C-Br), 991.12, 899.70, 811.21
(out-of-plane ring C-H bend), 716.30, 684.14, 665.41,
631.11, 614.47 (C-S); 1H NMR (CDCl3, δ ppm):
8.181-8.402 (m, 8H, Ar-H, PyH), 4.378-4.473 (m, 2H,
N-CH-Ar, CH-CH3), 1.401-1.461 (m, 3H, CH-CH3).
In vitro Evaluation of Antitumor Activity:
The newly synthesized 1,3-thiazolidin-4-one analogues
(4a-g) were studied for short term in vitro cytotoxicity
using Dalton’s ascites lymphoma (DAL) cells. The
712
DAL cells were maintained in Swiss albino mice by
intraperitoneal transplantation of 1×106 cells/animal.
The tumor (DAL) cells were aspirated from the
peritoneal cavity of tumor bearing mice were washed
thrice with normal saline (0.9% NaCl w/v) and
checked for viability using trypan blue dye exclusion
method34.
The DAL suspension was added to tubes containing 5
different concentrations of the test compounds and the
volume was made up to 1ml. Control tube contained
only cell suspension. Doxorubicin hydrochloride was
used as standard. These assay mixtures were incubated
for 3 h at 37˚ C. After incubation, 0.4% trypan blue
was added to each tube and mixed gently. The no of
dead cells and the percentage of these cells were
determined by using a hemocytometer. The antitumor
screening results were presented in Table 2.
Table 2: In vitro cytotoxicity of some novel 2-(4-substitutedphenyl)-5-methyl-3-(pyridin-4- yl)-1,3thiazolidin-4-ones (4a-g) against Dalton’s ascites lymphoma (DAL) cells
Percentage cell death, concentration in μg/ml
Compound
10
20
50
100
200
4a
01
06
07
22
49
4b
28
42
82
100
100
4c
04
10
22
29
42
4d
0
02
05
17
20
4e
0
0
06
14
20
4f
04
10
28
45
52
4g
18
22
49
78
89
Doxorubicin
20
55
75
100
100
Control tube contains only 1 dead cell.
Figure 1: Antitumor activity of synthesized 1,3-thiazolidin-4-one analogues (4a-g) against Dalton’s ascites
lymphoma cells
G. Nagalakshmi et al /Int.J. PharmTech Res.2011,3(2)
Measurement of potential cytotoxicity by MTT
Assay:
The cytotoxicity was further assessed by 3-(4,5dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide
(MTT) assay34-37, which is based on the reduction of
yellow
tetrazolium
salt
by
mitochondrial
dehydrogenase of metabolically active viable cells to a
blue-purple formazan that can be measured
spectrophotometrically. Hence, the intensity of the
colour in the solution is directly proportional to cell
viability. In order to evaluate the effects of the newly
synthesized 1,3-thiazolidin-4-one analogues (4a-g) on
cell proliferation, L929 lung fibroblast cells were used.
The cells were seeded into 96-well flat bottom titre
plates containing 200 μl minimum essential medium
(MEM) with 10% fetal calf serum (FCS) and
incubated for 24 h at 37˚ C with 5% (v/v) carbon
dioxide (CO2) atmosphere for the attachment of cells.
All test compounds were dissolved in dimethyl
sulfoxide (DMSO), prior to dilution. After incubation,
various concentrations of the test compound (0.2, 0.5,
1.0, 2.5, 5.0, 10.0 and 20.0 μg/ml) were added to the
wells in triplicates and the incubation was continued
for 48 h. Control groups included treatment with 0.1%
DMSO.
713
20 μl of MTT was added to each well before 4 h of the
completion of incubation. After the incubation period,
the plates were centrifuged, the supernatant was
removed and 100 μl of DMSO was added to each well,
to dissolve the formazan crystal produced by the MTT.
The plate was then incubated at room temperature for
15 min and the absorbance at optical density (OD) was
measured in an enzyme linked immunosorbent assay
(ELISA) reader (Auto reader 4011, Awareness
Technologies Inc., USA) at 570 nm with reference of
690 nm. Results were evaluated by comparing the
absorbance of the wells containing compound treated
cells with the absorbance of wells containing 0.1%
DMSO alone (solvent control). Conventionally, cell
viability was estimated to be 100% in the solvent
control. The results were expressed as IC50,
concentration causing 50% growth inhibition. IC50
values for each compound were calculated from doseresponse curves using linear regression analysis by
fitting the test concentrations that give percentage of
growth (PG) values and the results are given in Table
3. The relation between cell viability and drug
concentrations was plotted to obtain the survival curve
of lung tumor cell line of the specified compound is
illustrated in Figure 2 and 3.
Table 3: IC50 values of compound 4b and 4g against L929 lung fibroblast cell line
by MTT assay
a
Compound
IC50 (μg/ml)
L929
4b
15.3
4g
26.5
a
IC50 - concentration that causes 50% growth inhibition. aIC50 value was obtained
from a dose-response curve, mean of triplicate wells.
Figure 2: Dose response profile for compound 4b tested on L929 lung fibroblast cell line in vitro
G. Nagalakshmi et al /Int.J. PharmTech Res.2011,3(2)
714
Figure 3: Dose response profile for compound 4g tested on L929 lung fibroblast cell line in vitro
Results and Discussion
Chemistry:
In the present study, a series of novel 2(substitutedphenyl)-5-methyl-3-(pyridin-4-yl)-1,3thiazolidin-4-ones (4a-g) were synthesized according
to scheme 1. The target compounds (4a-g) were
prepared from pyridin-4-amine (1) which on
condensation with different aromatic aldehydes (2a-g)
in presence of catalytic amount of concentrated
hydrochloric acid in absolute ethanol yield N-[(Z)(substitutedphenyl)methylidene]pyridin-4-amine (3ag) in 62.5 - 86.4% yields (scheme 1). The physical data
of the synthesized compounds (3a-g) and (4a-g) are
presented in Table 1. The purity of the compounds was
checked by thin layer chromatography (TLC). The
structure of the synthesized compound (3a-g) was
confirmed on the basis of melting point, IR and 1H
NMR spectral data (experimental part).
The IR spectra of synthesized compounds (3a-g)
showed absorbtion bands ranging from 1615.90 1597.73 cm-1 for imine (>C=N) formation and 1686.44
- 1466.15 cm-1 for C=N and C=C ring stretch of
substituted phenyl and pyridyl ring. The IR spectra of
compound (3a-g) displayed bands at about 3147.26 3023.84 and 1313.29 - 1059.69 cm-1 associated with
aromatic C-H and C-F functions. In the IR spectra of
compound (3a-g), some significant stretching bands
due to C-Cl, C-Br, asymmetric ArNO2 and symmetric
ArNO2 were observed at 854.311 - 711.604 cm-1,
529.364 cm-1, 1582.56 - 1518.67 cm-1 and 1372.1 1341.25 cm-1, respectively. 1H NMR spectra of
compound 3a showed a sharp, singlet (1H) at δ 8.079
ppm attributed to azomethine (N=CH) and multiplet
(8H) observed at δ 7.286 - 7.593 ppm confirmed the
presence of four aromatic (phenyl) and four pyridyl
protons, respectively.
Compound (3a-g), which on cyclization with 2sulfanylpropanoic acid in dry 1,4-dioxane in presence
of anhydrous zinc chloride offers the corresponding 2(substitutedphenyl)-5-methyl-3-(pyridin-4-yl)-1,3thiazolidin-4-ones (4a-g) in 54.1 - 74.5% yields
(scheme 1). The structure of the synthesized
compound (4a-g) was established on the basis of IR
and 1H NMR spectral data (experimental part).
The IR spectrum of compound (4a-g) showed strong
absorbtion band at 1741.41 - 1701.87 cm-1 for C=O of
1,3-thiazolidin-4-one, while the band at 2982.37 2921.63 cm-1, 2853.17 cm-1, 1409.89 - 1366.58 cm-1
and 772.301 - 690.30 cm-1, respectively confirms the
presence of methyl C-H asymmetric, methyl C-H
symmetric, C-N stretch of tertiary aromatic amine and
C-S stretch. This is considered to be a strong
confirmation for the 1,3-thiazolidin-4-one nucleus
formation. The IR spectrum of compound (4a-g)
showed strong absorbtions bands in the aromatic C-H
region at 3140.68 cm-1 and strong C-Cl at 828.277 cm1
. The IR spectrum of compound (4a-g) showed
ArNO2 stretching bands at 1519.63 cm-1, 1273.75 cm1
, 862.025 cm-1, in addition to stretching band at
1461.32 - 1015.34 cm-1 attributed to C-F functions.
The IR spectra of compound (4a-g) displayed bands at
about 1644.0 - 1460.81 cm-1 associated with C=N and
C=C ring stretch of substituted phenyl and pyridyl
ring.
In the 1H NMR spectra of compound 4a, aromatic (4H)
and pyridyl (4H) protons appeared as a multiplet (8H)
at 7.422 - 7.021 ppm, C-2 of 1,3-thiazolidin-4-one, NCH-Ar proton appeared as a singlet (1H) at 2.970 ppm
and CH-CH3 protons appeared as a multiplet (3H) at
1.414 - 1.254 ppm and (1H) at 3.641 - 3.533 ppm,
which proved the closure of 1,3-thiazolidin-4-one ring.
G. Nagalakshmi et al /Int.J. PharmTech Res.2011,3(2)
Antitumor evaluation:
Chemotherapy is a major therapeutic approach for the
both localized and metastasized cancers. The newly
synthesized 1,3-thiazolidin-4-one analogues (4a-g) at
different concentration (10, 20, 50, 100 and 200
mcg/ml) were evaluated for in vitro cytotoxicity
against DAL cancer cells by trypan blue exclusion
method. The in vitro screening results are summarized
in Table 2.
Screening results of in vitro antitumor activity (Table
2) reveal that the compound 2-(2,4-dichlorophenyl)-5methyl-3-(pyridin-4-yl)-1,3-thiazolidin-4-one
(4b)
and 2-(4-bromophenyl)-5-methyl-3-(pyridin-4-yl)-1,3thiazolidin-4-one (4g) inhibited 100% and 78% DAL
tumor cells at 100 mcg/ml and 100% and 89% at 200
mcg/ml concentration, whereas standard drug
doxorubicin exhibit 100% DAL inhibition at a
concentration of 100 mcg/ml. At a higher
concentration of 200 mcg/ml, compound 4a, 4c and 4f
inhibited 49%, 42% and 52% DAL tumor cells,
exhibited moderate antitumor activity, whereas
compound 4d and 4e both inhibited 20% DAL tumor
cells displayed mild antitumor activity. 1,3-thiazolidin4-one analogues (4a-g) exhibit dose-dependent
significant increase in cytotoxicity when compared to
those of standard drug, doxorubicin.
From the above study, compounds 4b and 4g which
showed > 50% inhibition at a concentration of 100
mcg/ml were selected for their in vitro antiproliferative
activity against L929 lung fibroblast cell line by using
MTT assay method.
Evaluation of antiproliferative activity:
Induction of cell death or inhibition of cell
proliferation is an important property for
chemotherapeutic agents. The antiproliferative effect
of compound 4b and 4g was evaluated by measuring
the level of cell proliferation after incubation of the
cells with the test samples using MTT colorimetric
assay, which evaluates the capacity of the
mitochondrial enzyme succinate dehydrogenase of
viable cells to reduce MTT to formazan crystals. The
results were expressed as percentage of cell
proliferation compared with cells in control (cells
treated with vehicle, DMSO 0.1%).
The selected novel 1,3-thiazolidin-4-one analogues (4b
and 4g) at different concentrations (0.5, 1.0, 2.5, 5.0,
10.0 and 20.0 mcg/ml) were tested for their in vitro
antiproliferative activity against L929 lung fibroblast
cell lines using MTT assay. The resulting IC50 values
715
are summarized in Table 3. The viability data was used
to calculate the IC50 values and the relationship
between percent viability and the compound
concentration is illustrated in Figure 2 and 3.
Among the compounds screened, compound 2-(2,4dichlorophenyl)-5-methyl-3-(pyridin-4-yl)-1,3thiazolidin-4-one 4b showed potent inhibitory
activities (65.37%) at 20 mcg/ml concentration as
illustrated by a lowest IC50 value of 15.3 μg/ml.
Compound 2-(4-bromophenyl)-5-methyl-3-(pyridin-4yl)-1,3-thiazolidin-4-one 4g showed mild inhibitory
(38.91%) at 20 mcg/ml concentration with an IC50
value of 26.5 μg/ml.
Furthermore, results illustrated that compound 4b and
4g exhibited highest antiproliferative activity against
L929 cells in vitro, and can therefore be candidates for
further stages of screening in vivo.
From the antitumor and antiproliferative activity data
reported in Table 2 and Table 3, it may be inferred that
antitumor activity is strongly dependent on the nature
of the substituent at C-2 and N-3 of the 1,3-thiazolidin4-one ring. In a particular, a high activity level was
observed for compounds 4b and 4g possessing a 2,4dichlorophenyl and 4-nitrophenyl group substituted at
C-2 and pyridin-4-yl ring at N-3 position of 1,3thiazolidin-4-one nucleus.
Conclusion
In this study, compound 2-(2,4-dichlorophenyl)-5methyl-3-(pyridin-4-yl)-1,3-thiazolidin-4-one 4b and
2-(4-bromophenyl)-5-methyl-3-(pyridin-4-yl)-1,3thiazolidin-4-one 4g exhibited significant antitumor
and antiproliferative activity against DAL and L929
cells in vitro. These two compounds could be
considered as useful templates or leads for the future
development and further structural variation to obtain
more potent, selective and less toxic antitumor agents.
Acknowledgements
The authors are thankful to Jadavpur University,
Kolkata for providing the necessary facilities to carry
out this research work. The authors also express their
sincere thanks and gratitude to AICTE, Quality
Improvement Programme (New Delhi) for the
financial assistance provided to carry out this research
work and also to the Head, Indian Institute of
Chemical Biology (IICB), Kolkata for providing
spectral data.
G. Nagalakshmi et al /Int.J. PharmTech Res.2011,3(2)
References
1. Zhou H., Wu S., Zhai S., Liu A., Sun Y., Li
R., Zhang Y., Ekins S., Swaan P.W., Fang B.,
Zhang B. and Yan B., Design, synthesis,
cytoselective
toxicity,
structure-activity
relationships
and
pharmacophore
of
thiazolidinone derivatives targeting drugresistant lung cancer cells, J. Med. Chem.,
2008, 51, 1242-1251.
2. Vigorita M.G., Ottana R., Monforte F.,
Maccari R., Trovato A., Monforte M.T. and
Taviano
M.F.,
Synthesis
and
antiinflammatory, analgesic activity of 3,3'-(1,2Ethanediyl)-bis[2-aryl-4-thiazolidinone] chiral
compounds. Part 10, Bioorg. Med. Chem.
Lett., 2001, 11, 2791-2794.
3. Geronikaki A.A., Lagunin A.A., HadjipavlouLitina D.I., Eleftheriou P.T., Filimonov D.A.,
Poroikov V.V., Alam I. and Saxena A.K.,
Computer-Aided
discovery
of
antiinflammatory thiazolidinones with dual
cyclooxygenase/lipooxygenase inhibition, J.
Med. Chem., 2008, 51, 1601-1609.
4. Ottana R., Carolti S., Maccari R., Landini I.,
Chiricosta G., Cariagli B., Vigorita M.G. and
Mini E., In vitro antiproliferative activity
against human colon cancer cell lines of
representative 4-thiazolidinones. Part I,
Bioorg. Med. Chem. Lett., 2005, 15, 39303933.
5. Chandrappa S., Chandru H., Sharada A.C.,
Vinaya K., Anandakumar C.S., Thimmegowda
N.R., Nagegowda P., Karunakumar M. and
Rangappa K.S., Synthesis and in vivo
anticancer and antiangiogenic effects of novel
thioxothiazolidin-4-one derivatives against
transplantable mouse tumor, Med. Chem. Res.,
2010, 19, 236-249.
6. Balzarini J., Krzesinska B.O., Maurin J.K. and
Orzeszko A., Synthesis and anti-HIV studies
of 2- and 3-adamantyl-substituted thiazolidin4-ones, Eur. J. Med. Chem., 2009, 44, 303311.
7. de Aquino T.M., Liesen A.P., da Silva R.E.A.,
Lima V.T., Carvelho L.C.S., de Faria A.R., de
Araujo J.M., de Lima J.G., Alves A.J., de
Melo E.J.T. and Goes A.J.S., Synthesis, antiToxoplasma gondii and antimicrobial activities
of
benzaldehyde
4-phenyl-3thiosemicarbazones
and
2[(phenylmethylene)hydrazono]-4-oxo-3phenyl-5-thiazolidineacetic acids, Bioorg.
Med. Chem., 2008, 16, 446-456.
716
8. Ramachandran R., Rani M. and Kabilan S.,
Design, synthesis and biological evaluation
novel 2-[(2,4-diaryl-3-azabicyclo[3.3.1]nonan9-ylidene)hydrazono]-1,3-thiazolidin-4-ones
as a new class of antimicrobial agents, Bioorg.
Med. Chem. Lett., 2009, 19, 2819-2823.
9. Babaoglu K., Page M.A., Jones V.C., Mc Neil
M.R., Dong C., Naismith J.H. and Lee R.E.,
Novel inhibitors of an emerging target in
Mycobacterium
tuberculosis;
substituted
thiazolidinones as inhibitors of dTDPrhamnose synthesis, Bioorg. Med. Chem.
Lett., 2003, 13, 3227-3230.
10. Singh B., Mehta D., Baregama L.K. and
Talesara G.L., Synthesis and biological
evaluation of 7-N-(n-alkoxyphthalimido)-2hydroxy-4-aryl-6-aryliminothiazolidino[2,3b]pyrimidines and related compounds, Indian J
Chem., 2004, 43B, 1306-1313.
11. Smith T.K., Young B.L., Denton H., Hughes
D.L. and Wagner G.K., First small molecular
inhibitors of T. brucei dolichophosphate
mannose synthase (DPMS), a validated drug
target in African sleeping sickness, Bioorg.
Med. Chem. Lett., 2009, 19 (6), 1749-1752.
12. Ottana R., Maccari R., Ciurleto R., Vigorita
M.G., Panico A.M., Cardile, V., Garufi, F and
Ronsivalle, S., Synthesis and in vitro
evaluation of 5-arylidene-3-hydroxyalkyl-2phenylimino-4-thiazolidinones
with
antigenerative activity on human chondrocyte
cultures, Bioorg. Med. Chem., 2007, 15, 76187625.
13. Ulusoy N., Ergenc N., Ekinci A.C. and Ozer
H., Synthesis and anticonvulsant activity of
some new arylidenehydrazides and 4thiazolidinones, Monatshefte fur Chemie.,
1996, 127, 1197-1202.
14. Diurno M.V., Mazzoni O., Correale G.,
Monterrey I.G., Calignano A., Rana G.L. and
Bolognese A., Synthesis and structure-activity
relationships of 2-(substitutedphenyl)-3-[3(N,N-dimethylamino)propyl]-1,3-thiazolidin4-ones acting as H1-histamine antagonists, IL
Farmaco., 1999, 54, 579-583.
15. Zarghi, A., Najafnia, L., Daraee, B., Dadrass,
O.G. and Hedayati, M., Synthesis of 2,3diaryl-1,3-thiazolidin-4-one derivatives as
selective cyclooxygenase (COX-2) inhibitors,
Bioorg. Med. Chem. Lett., 2007, 17 (20),
5634-5637.
16. Shingalapur R.V., Hosamani K.M., Keri R.S.
and Hugar M.H., Derivatives of benzimidazole
pharmacophore: synthesis, anticonvulsant,
G. Nagalakshmi et al /Int.J. PharmTech Res.2011,3(2)
717
antidiabetic and DNA cleavage studies, Eur. J.
Med. Chem., 2010, 45, 1753-1759.
derivatives, J. Med. Chem., 1992, 35, 36863690.
17. Jackson C.M., Blass B., Coburn K.,
Djandjighian L., Fadayel G., Fluke A.J.,
Hodson S.J., Janusz J.M., Murawskej M.,
Ridgeway J.M., White R.E. and Wu S.,
Evaluation of thiazolidine-based blockers of
human Kv1.5 for the treatment of atrial
arrhythmias, Bioorg. Med. Chem. Lett., 2007,
17, 282-284.
25. Hu L., Li Z., Wang Y., Wu Y., Jiang J.D. and
Boykin D.W., Novel pyridinyl and
pyrimidinylcarbazole
sulfonamides
as
antiproliferative agents, Bioorg. Med. Chem.
Lett., 2007, 17, 1193-1196.
18. Bhandari S.V., Bothara K.G., Patil A.A.,
Chitra T.S., Sarkate A.P., Gore S.T., Dangre
S.C. and Kanchane C.V., Design, Synthesis
and pharmacological screening of novel
antihypertensive agents using hybrid approach,
Bioorg. Med. Chem., 2009, 17, 390-400.
19. Chezal J.M., Paeshuyse J., Gaumet V.,
Canitrot D., Maisonial A., Lartigne C.,
Gueiffier A., Moreau E., Teulade J.C.,
Chavignon O. and Neyts J., Synthesis and
antiviral activity of an imidazo[1,2a]pyrrolo[2,3-c]pyridine series against the
bovine viral diarrhea virus, Eur. J. Med.
Chem., 2010, 45, 2044-2047.
20. Desai B., Sureja D., Naliapara Y., Shah A. and
Saxena A.K., Synthesis and QSAR studies of
4-substitutedphenyl-2,6-dimethyl-3,5-Bis-N(substitutedphenyl)carbamoyl-1,4dihydropyridines as potential antitubercular
agents, Bioorg. Med. Chem., 2001, 9, 19931998.
21. Martinez-Urbina M.A., Zentella A., VilchisReyes M.A., Guzman A., Vargas O., Apan
M.T.R., Gallegos J.L.V. and Diaz E., 6substituted-2-(Ntrifluoroacetylamino)imidazopyridines induce
cell cycle arrest and apoptosis in SK-LU-1
human cancer cell line, Eur. J. Med. Chem.,
2010, 45, 1211-1219.
22. Shi F., Li C., Xia M., Miao K., Zhao Y., Tu S.,
Zheng W., Zhang G. and Ma N., Green
chemoselective synthesis of thiazolo[3,2a]pyridine derivatives and evaluation of their
antioxidant and cytotoxic activities, Bioorg.
Med. Chem. Lett., 2009, 19, 5565-5568.
23. Willemann C., Grunert R., Bednarski P.J. and
Troschutz R., Synthesis and cytotoxic activity
of 5,6-heteroaromatically annulated pyridin2,4-diamines, Bioorg. Med. Chem., 2009, 17,
4406-4419.
24. Temple C., Rener G.A., Waud W.R. and
Noker P.E., Antimitotic Agents: StructureActivity studies with some pyridine
26. Li J., Chen S.H., Li X., Niu C. and Doyle
T.W., Efficient synthesis of ribonucleotide
reductase
inhibitors
3-aminopyridin-2carboxaldehyde thiosemicarbazone (3-AP) and
3-amino-4-methylpyridin-2-carboxaldehyde
thiosemicarbazone (3-AMP) via palladium
mediated
cross-coupling
reactions,
Tetrahedron., 1998, 54, 393-400.
27. Matsuno K., Sawada J., Sugimoto M., Ogo N.
and Asai A., Bis(hetero)aryl derivatives as
unique kinesin spindle protein inhibitors,
Bioorg. Med. Chem. Lett., 2009, 19, 10581061.
28. Basnet A., Thapa P., Karki R., Choi H., Choi
J.H., Yun M, Jeong B.S., Jahng Y., Na Y.,
Cho W.J., Kwon Y., Lee C.S. and Lee E.S.,
2,6-Dithienyl-4-furylpyridines:
Synthesis,
topoisomerase I and II inhibition, cytotoxicity,
structure-activity relationship and docking
study, Bioorg. Med. Chem. Lett., 2010, 20, 4247.
29. Nason D.M., Heck S.D., Bodenstein M.S.,
Lowe J.A., Nelson R.B., Liston D.R., Nolan
C.E., Lanyon L.F., Ward K.M. and Volkmann
R.A.,
Substituted
6-phenyl-pyridin-2ylamines: selective and potent inhibitors of
neuronal nitric oxide synthase, Bioorg. Med.
Chem. Lett., 2004, 14, 4511-4514.
30. Davis L., Olsen G.E., Klein J.T., Kapples K.J.,
Huger F.P., Smith C.P., Petro W.W., Cornferdt
M.
and
Effhard
R.C.,
Substituted
(pyrroloamino)pyridines: Potential agents for
the treatment of Alzheimer’s disease, J. Med.
Chem., 1996, 39, 582-587.
31. Kumar S., Dhar D.N. and Saxena P.N.,
Applications of metal complexes of Schiff
bases-A review, Journal of Scientific &
Industrial Research., 2009, 68, 181-187.
32. Vicini P., Geronikaki A., Incerti M., Busonera
B., Poni G., Kabras C.A. and Colla P.L.,
Synthesis and biological evaluation of
benzo[d]isothiazole,
benzothiazole
and
thiazole Schiff bases., Bioorg. Med. Chem.,
2003, 11, 4785-4789.
33. Kar D.M., Sahu S.K., Pradhan D., Dash G.K.
and Mishra P.K., Synthesis, antimicrobial and
anti-inflammatory activities of some novel
G. Nagalakshmi et al /Int.J. PharmTech Res.2011,3(2)
isatinoid compounds, J Teach Res Chem.,
2003, 10, 20-24.
34. Richardson D.R., Tran E.H. and Ponka P., The
potential of iron chelators of the pyridoxal
isonicotinoyl hydrazone class of effective
antiproliferative agents, Blood., 1995, 86,
4295-4306.
35. Mosmann T., Rapid colorimetric assay for
cellular growth and survival: application to
proliferation and cytotoxicity assays, J.
Immunol. Methods., 1983, 65, 55-63.
36. Richardson D.R. and Milnes K., The potential
of iron chelators of the pyridoxal isonicotinoyl
718
hydrazone class of effective antiproliferative
agents II: The mechanism of action of ligands
derived
from salicylaldehyde
benzoyl
hydrazone and 2-hydroxy-1-naphthylaldehyde
benzoyl hydrazone, Blood., 1997, 89, 30253038.
37. Soliman A.M.M., Synthesis, antitumor activity
and molecular docking study of novel
sulfonamide-schiff’s base, thiazolidinones,
benzothiazinones and their C-nucleoside
derivatives, Eur. J. Med. Chem., 2010, 45,
572-580.
*****