5-N-Substituted-2-(substituted benzenesulphonyl) glutamines as antitumor agents. Part II: Synthesis, biological activity and QSAR study

Article abstract of DOI:10.1016/j.bmc.2004.01.006

Cancer is a major killer disease throughout human history. Thus, cancer becomes a major point of interest in life science. It was proved that cancer is a nitrogen trap and tumor cells are avid glutamine consumers. The non-essential amino acid glutamine, which is a glutamic acid derivative, supplies its amide nitrogen to tumor cells in the biosynthesis of purine and pyrimidine bases of nucleic acids as well as takes part in protein synthesis. Based on these and in continuation of our composite programme of development of new potential anticancer agents through rational drug design, 17 new 5-N-Substituted-2- (substituted benzenesulphonyl) glutamines were selected for synthesis. These compounds as well as 36 earlier synthesized glutamine analogues were screened for antitumor activity using percentage inhibition of tumor cell count as the activity parameter. QSAR study was performed with 53 compounds in order to design leads with increased effectiveness for antitumor activity using both physicochemical and topological parameters. QSAR study showed that steric effect on the aromatic ring is conducive to the activity. n-butyl substitution on aliphatic side chain and atom no 12 is important for antitumor activity of glutamine analogues.

Full text of DOI:10.1016/j.bmc.2004.01.006

Bioorganic & Medicinal Chemistry 12 (2004) 1413–1423
5-N-Substituted-2-(substituted benzenesulphonyl) glutamines as
antitumor agents. Part II: Synthesis, biological activity and QSAR
study
Soma Samanta, K. Srikanth,y Suchandra Banerjee,{ Bikash Debnath, Shovanlal Gayen
and Tarun Jha*
Division of Pharmaceutical and Medicinal Chemistry, Department of Pharmaceutical Technology, PO Box 17020,
Jadavpur University, Kolkata-700032, India
Received 27September 2003; accepted 7January 2004
Abstract—Cancer is a major killer disease throughout human history. Thus, cancer becomes a major point of interest in life science.
It was proved that cancer is a nitrogen trap and tumor cells are avid glutamine consumers. The non-essential amino acid glutamine,
which is a glutamic acid derivative, supplies its amide nitrogen to tumor cells in the biosynthesis of purine and pyrimidine bases of
nucleic acids as well as takes part in protein synthesis. Based on these and in continuation of our composite programme of devel-
opment of new potential anticancer agents through rational drug design, 17new 5- N-Substituted-2-(substituted benzenesulphonyl)
glutamines were selected for synthesis. These compounds as well as 36 earlier synthesized glutamine analogues were screened for
antitumor activity using percentage inhibition of tumor cell count as the activity parameter. QSAR study was performed with 53
compounds in order to design leads with increased effectiveness for antitumor activity using both physicochemical and topological
parameters. QSAR study showed that steric effect on the aromatic ring is conducive to the activity. n-butyl substitution on aliphatic
side chain and atom no 12 is important for antitumor activity of glutamine analogues.
# 2004 Elsevier Ltd. All rights reserved.
1. Introduction
building block of proteins. Other than glucose it is one
of the major substrates, if not the major substrate, for
the energy metabolism of rapidly growing tumor cells.5
Beside glucose, glutamine is assumed to be the main
energy source in tumor cells.5 Since no cells, whether
cancerous or normal, cannot survive without the only
circulatory sugar glucose whereas glutamine is a non-
essential amino acid which is required by most of the
cells and tissues, points out that it may be the major
substrate for cancer. It also plays a central role in mul-
tiple metabolic pathways and considered to be the most
essential component of tissue/cell culture media6 for not
only as the nitrogen source but also as the carbon
source. Since most of the cells need non-essential amino
acid glutamine for physiological functions and most of
those normal cells are transformable to cancerous one,
glutamine may play a significant role in cancer. After a
definite time interval, all cells start mutation in cell culture
medium, which is also indicative for the role of glutamine
in cancer.7
Cancer is a disease of worldwide importance because it
is a major killer throughout human history. Cancer has
been described as a nitrogen trap.1,2 The importance of
non-essential amino acid glutamine in proliferation of
human tumor cells was studied extensively.3,4 All tumor
cells studied were found to have a high activity of
phosphate-dependent glutaminase utilizing glutamine
from the medium during long-term culture.3 Human
hepatoma cells take up glutamine at rates several fold
faster than the normal human hepatocytes.4 l-glutamine
is not only the precursor of the biosynthesis of purine
and pyrimidine bases of DNA as well as used us a
Keywords: Glutamine analogues; Synthesis; Anticancer activity; Cell
count inhibition; QSAR study.
* Corresponding author. Tel.: +91-33-2414-6677; fax: 91-33-2414-
6677; e-mail: tjjupharm@yahoo.com
y
Present address: Department of Medicinal Chemistry, College of
Pharmacy, University of Minnesota, 8-125 Weaver Densford Hall,
308 Harvard St. S.E., Minneapolis, MN 55455, USA.
Present address: Indian Institute of Chemical Biology, 4, Raja S. C.
{
Aryl sulphatase C (ASC) family of transporters is involved
in the mediation of glutamine uptake and glutamine, in
Mullick Road, Kolkata 700 032, India.
0968-0896/$ - see front matter # 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2004.01.006

1414
S. Samanta et al. / Bioorg. Med. Chem. 12 (2004) 1413–1423
the form of glutamate, and cysteine are supplied perhaps
for glutathione synthesis.8 Glutamine dependant syntheses
of Interleukin-2 by lymphocytes and Interleukin-1 by mac-
rophages are hampered in cancer. These resulted in part to
immunosuppression, which is a common manifestation
of most of the anticancer drugs.9 Reintroduction of tha-
lidomide, a glutamic acid derivative, in a clinical trial
for the treatment of various malignant tumors also
supported the role of glutamine in cancer.10 Besides
these, azaserine and acivicin are antiglutamine agents.11
Thus, the structural variants of glutamine attracted our
attention to develop possible anticancer agents, which
may act through glutamine and/or folic acid antagonism.
tumor cell count were calculated by comparing the cell
count of the test (T) with that of the control (C) using
the expression (1ÀT/C) Â100.% Inhibition of tumor
cell count was considered as the biological activity data
for QSAR study. Biological activity data of these 53
5-N-substituted-2-(substituted benzenesulphonyl) gluta-
mines are shown in Table 3. Some of the compounds
possess promising anticancer activity and draw attention
for future research on those.
2.3. QSAR
In order to identify the chemical structural features
required and/or responsible for antitumor activity of 5-
N-substituted-2-(substituted benzenesulphonyl) glutamines
attempts have been made to perform QSAR studies
using physicochemical parameters as well as E-state
index.22À30 E-state value of each atom contains electro-
nic and topological structural informations from all
other atoms within the structure.
We have previously reported synthesis, biological eval-
uation by percentage inhibition of tumor weight and
Quantitative Structure-Activity Relationship (QSAR)
studies on some glutamine and glutamamide analogues
as possible anticancer agents12À18 as a part of our
composite programme of rational drug design.12À24 Here
in this article, 17new 5- N-substituted-2-(substituted
benzenesulphonyl) glutamines, as shown in Figure 1,
were synthesized in continuation of our earlier work.16
These compounds as well as 36 earlier synthesized glu-
tamine analogues16 were screened for antitumor activity
using percentage inhibition of tumor cell count as the
activity parameter. QSAR studies were done using all 53
biologically evaluated glutamine analogues to explore
the substitutional requirement to optimize leads for the
improved anticancer activity.12À17
The congener series possesses the substitution on aromatic
ring system at 10, 20, 30, 40 positions denoted as R1, R2, R3,
R4 respectively and at 5-N position of the aliphatic side
2. Results
2.1. Synthesis
Synthesis of the 5-N-substituted-2-(substituted benzene-
sulfonyl) glutamines were carried out in accordance with
the Scheme 1 and the chemistry behind the synthesis is
explained in the Experimental section. Physical data of
all of the intermediates and final compounds are furn-
ished in Tables 1 and 2, respectively. The yields of the
title compounds were found good as shown in Table 2.
2.2. Biological evaluation
These 17final compounds as well as 36 earlier synthe-
sized glutamine analogues were biologically evaluated
by dissolving those in phosphate buffered saline (PBS)
or by suspending in PBS or by suspending in PBS with
2% Tween 80 (whenever necessary) separately. The
solution or suspension of the test compounds were
administered at a dose level of 2 mmol/kg/day intraperi-
tonially (ip) for 7consecutive days. One day after the
intraperitonial inoculation of each mouse with 2Â106
Ehrlich Ascites Carcinoma (EAC) cells,% inhibitions of
Figure 1. General structure of 5-N-substituted-2-(substituted benze-
nesulphonyl)-glutamines.
Scheme 1. General synthetic route for the preparation of 5- N-sub-
stituted-2-(substituted benzenesulphonyl)-glutamines.

S. Samanta et al. / Bioorg. Med. Chem. 12 (2004) 1413–1423
Table 1. Physical data of the intermediate compounds
1415
Compda
R1
R2
R3
R4
M.P. (ꢀC)
%Yield
Molecular formula
MW
Elemental analysis (%)
Found calculated
C
H
N
C
H
N
2a
2b
2c
3a
3b
3c
4a
4b
4c
H
Cl
H
H
Cl
H
H
Cl
H
NO2
H
H
NO2
H
H
NO2
H
H
H
H
Br
H
H
Br
H
H
CH3
H
H
CH3
H
H
CH3
H
60–62
17–19
73–75
107–108
131–133
148–150
80–81
82.23
80.31
77.90
74.30
60.32
80.84
79.42
C6H4N1O4 S1Cl
C7H6O2 S1 Cl2
C6H4O2Br S1Cl
C11H12N2O8 S1
C12H14N1O6 S1Cl
C11H12N1O6 S1Br
C11H10N2O7 S1
12H12N1O5 S1Cl
11H10N1O5 S1Br
221.62
225.09
255.52
332.29
32.31
36.89
28.11
39.45
1.73
2.58
1.48
3.53
6.21
—
—
8.39
32.48
37.32
28.18
39.72
1.80
2.66
1.56
3.61
6.32
—
—
8.43
3365.7 42.66
4.21 4.0742.89
3.1743.7 36.05
4.174.16
366.19
314.28
317.76
348.18
35.88
3.28
42.00
45.32
37.91
3.82
3.18
3.78
3.45
41.92
45.12
37.84
3.14
3.68
3.39
8.78
4.29
3.95
8.91
4.41
4.02
H
Br
165–16788.00
95–9764.00
C
C
a Compd=Compound.
Table 2. Physical data of different substituted benzenesulphonyl glutamines 5–21
Compda
R1
R2
R3
R4
R5
M.P. (ꢀC)
% Yield
Molecular formula
M.W
5
6
7
8
H
H
H
H
H
H
H
Cl
Cl
Cl
Cl
Cl
H
H
H
H
H
NO2
NO2
NO2
NO2
NO2
NO2
NO2
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
Br
Br
Br
Br
Br
H
H
H
H
H
CH3
C2H5
n-C3H7
i-C3H7
C6H5
n-C4H9
n-C6H13
i-C3H7
n-C3H7
n-C4H9
i-C4H9
C6H5CH2
n-C4H9
n-C6H13
n-C3H7
i-C4H9
C6H5
148–150
169–171
173–175
171–173
194–196
154–156
139–141
149–151
58.02
63.70
65.30
70.00
59.51
64.80
70.00
53.80
C
57.80
59.37C
55.70
88.16
77.50
85.50
88.16
78.90
C12H15N3O7S1
C13H17N3O7S1
C14H19N3O7S1
C14H19N3O7S1
C17H17N3O7S1
C15H21N3O7S1
C17H25N3O7S1
C15H21N2O5S1Cl
15H21N2O5S1Cl
C16H23N2O5S1Cl
16H23N2O5S1Cl
C19H21N2O5S1Cl
C15H21N2O5S1Br
C17H25N2O5S1Br
C14H19N2O5S1Br
C15H21N2O5S1Br
C17H17N2O5S1Br
345.33
359.36
373.39
373.39
407.40
387.41
415.47
376.87
376.87
390.89
390.89
424.90
421.31
449.37
407.29
421.31
441.30
9
10
11
12
13
14
15
16
17
18
19
20
21
H
H
CH3
CH3
CH3
CH3
CH3
H
H
H
H
H
115–11760.20
84–86
123–125
119–121
201–202
145–147
197–199
204–205
228–230
H
H
H
H
H
a Compd=Compound.
chain, which is designated as R5 as shown in Figure 1.
Physicochemical parameters were considered as the sum of
the substitutents on the benzene ring for each compound.
Among the various physicochemical parameters only
MR value was considered. The E-state (ETSA) index is an
atom/sub-molecular descriptor encoding both electronic
and topological information. ETSA indices of the common
atoms were calculated by using a computer programme
‘Mouse’ written in C++ language and developed in our
laboratory.31 The software can run in windows operating
system and can calculate ETSA indices only. For calcu-
lation of E-state index, arbitrary numbering was used
and these are shown in Figure 2. The physicochemical
parameter ꢀMR (sum of MR values at R1, R2, R3, R4
positions of the benzene ring), E-state index S12 and
indicator parameter I, which were used in developing
QSAR equations, are shown in Table 3. Correlation
analysis of various physicochemical and topological
parameters used in developing QSAR equations was
performed. The intercorrelated parameters were dis-
carded depending on their individual correlation with the
biological activity (log BA). All possible combinations of
parameters were considered. The resultant parameters
were subjected to multiple regression analysis using log
BA as the biological activity parameter with the help of
a software ‘Multiregress’ developed in our laboratory.32
The best possible combination of parameters, which is
best fitted with the biological activity data found, was
used for developing QSAR equations.
Stepwise development of the regression equation with
various physicochemical parameters and deleting inter-
correlated parameters, various combinations were tried
and the best uni-parametric equation was
Log BA ¼ 1:133 ðÆ0:094Þ þ 0:458 ðÆ0:084ÞꢀMR ð1Þ
N ¼ 53; R ¼ 0:606; %EV ¼ 36:68; F ¼ 29:549;
p < 0:0000; S:E:E ¼ 0:167; SSY ¼ 2:241;
PRESS ¼ 1:5198; q2 ¼ 0:322; SPRESS ¼ 0:173;
PSE ¼ 0:169
where ꢀMR is sum of the molar refractivities of the
substituents in the benzene ring, N is the number of
data points, R, %EV, F, p, S.E.E., SSY, PRESS, q2,
SPRESS, P.S.E are correlation coefficient, percentage
of explained variance, ratio between the variances of
observed and calculated activities, probability factor
related to the F-ratio, standard error of estimate, sum

1416
S. Samanta et al. / Bioorg. Med. Chem. 12 (2004) 1413–1423
Table 3. Antitumor activities and QSAR parameters of fifty three 5- N-substituted-2-(substituted benzenesulphonyl)-glutamines 5–57
Compda
R1
R2
R3
R4
R5
S12
I
ꢀMR
BA (%TCI)
Log BA
5
6
7
8
H
H
H
H
H
H
H
Cl
Cl
Cl
Cl
Cl
H
H
H
H
H
H
H
H
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
H
H
H
H
H
H
H
H
H
NO2
NO2
NO2
NO2
NO2
NO2
NO2
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
NO2
NO2
NO2
NO2
NO2
NO2
NO2
NO2
NO2
NO2
NO2
NO2
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
Br
Br
Br
Br
Br
H
CH3
CH3
H
H
H
H
H
H
CH3
C2H5
n-C3H7
i-C3H7
C6H5
n-C4H9
n-C6H13
i-C3H7
n-C3H7
n-C4H9
i-C4H9
C6H5CH2
n-C4H9
n-C6H13
n-C3H7
i-C4H9
C6H5
i-C4H9
i-C3H7
i-C4H9
H
CH3
C2H5
n-C3H7
n-C4H9
i-C3H7
i-C4H9
C6H11
C6H5
C6H5CH2
n-C5H11
n-C6H13
H
11.117
11.186
11.243
11.251
11.387
11.289
11.361
11.303
11.295
11.341
11.3470.000
11.460
11.269
11.341
11.222
11.269
11.3670.000
11.228
11.238
11.282
11.093
11.202
11.271
11.328
11.374
11.336
11.380
11.504
11.472
11.493
11.413
11.446
11.062
11.171
11.241
11.2970.000
11.343
11.382
11.415
11.305
11.349
11.473
11.462
11.441
11.150
11.220
11.276
11.322
11.361
11.394
11.284
11.441
11.420
0.000
0.000
0.000
0.000
0.000
1.000
0.000
0.000
0.000
1.000
0.740
0.740
0.740
0.740
0.740
0.740
0.740
1.160
1.160
1.160
21.74
31.34
10.47
41.38
32.75
1.337
1.496
1.020
1.617
1.515
1.658
1.689
1.501
1.920
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
H
H
45.45
48.86
CH3
CH3
CH3
CH3
CH3
H
H
H
H
H
31.69
83.098
92 61.971.7
1.160
0.890
40.00
1.602
1.597
0.000
1.000
0.000
0.000
0.000
1.160
0.890
0.890
0.890
0.890
56.42
41.76
48.71
20.88
30.76
1.751
1.621
1.688
1.320
1.488
39.56
H
H
H
0.000
0.000
0.000
0.000
0.000
0.000
0.000
1.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.560
0.560
1.300
1.300
1.300
1.300
1.300
1.300
1.300
1.300
1.300
1.300
1.300
1.300
1.300
1.300
1.300
12.68
19.13
20.80
19.35
46.77
66.19
45.00
89.36
42.20
76.29
71.80
33.3
70.15
78.89
67.38
40.32
56.06
31.29
1.103
1.282
1.318
1.287
1.670
1.821
1.653
1.951
1.625
1.882
1.856
1.522
1.846
1.897
1.828
1.605
1.749
1.495
NO2
NO2
NO2
NO2
NO2
NO2
NO2
NO2
NO2
NO2
NO2
NO2
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
C2H5
C2H5
C2H5
C2H5
C2H5
C2H5
C2H5
C2H5
C2H5
CH3
C2H5
n-C3H7
n-C4H9
n-C5H11
n-C6H13
i-C3H7
i-C4H9
C6H11
C6H5CH2
C6H5
1.300
32.28
1.509
1.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
1.000
0.000
0.000
0.000
0.000
0.000
1.300
1.300
1.300
1.300
1.300
1.300
1.300
1.300
1.030
1.030
1.030
1.030
1.030
1.030
1.030
1.030
1.030
80.74
61.8
1.907
1.791
1.814
1.763
1.798
1.588
1.450
1.680
1.540
1.615
1.393
1.705
1.532
1.848
65.14
57.97
62.85
38.75
28.22
47.88
34.65
41.20
24.73
50.68
34.06
70.47
H
H
H
H
H
H
H
H
H
H
H
H
CH3
C2H5
n-C3H7
n-C4H9
n-C5H11
n-C6H13
i-C3H7
C6H5CH2
C6H5
33 54.071.7
65.23
52.36
100.00
100.00
100.00
1.814
1.719
2.000
2.000
2.000
Mitomycin C
Azaserine
DON
a Compd=Compound.
LogBA ¼ ꢀ6:305 ðÆ2:434Þ þ 0:380 ðÆ0:082Þ ꢀMR
þ 0:665 ðÆ0:217Þ S12
N ¼ 53; R ¼ 0:683; %EV ¼ 46:66; F ¼ 21:869;
p < 0:0000; S:E:E ¼ 0:155; SSY ¼ 2:241;
PRESS ¼ 1:342; q2 ¼ 0:401; SPRESS ¼ 0:164;
PSE ¼ 0:159
of square of regression values, predicted residual sum of
square, cross validated R2, uncertainty factor, predictive
standard error respectively. ꢀMR explains 36.68% of the
variances in the activity data. Positive coefficient of ꢀMR
indicated that the steric effect at benzene ring of these
compounds is conducive to the anticancer activity. It
may be hypothesized that the benzene ring of the sub-
stituted benzenesulphonyl glutamines has a tendency to
interact with the receptor via dispersion forces. Com-
bining E-state index along with ꢀMR slightly improve
the quality of the relation as follows:
ð2Þ
Eq 2 explains 46.66% of the variation in anticancer
activity. The ETSA index of atom 12 (S12) in the equation

S. Samanta et al. / Bioorg. Med. Chem. 12 (2004) 1413–1423
1417
LogBA ¼ ꢀ9:177 ðÆ2:061Þ þ 0:402 ðÆ0:066Þ ꢀMR
þ 0:916 ðÆ0:184Þ S12 þ 0:148 ðÆ0:054Þ I
DC ¼ 13; 33; 47; 46; N ¼ 49; R ¼ 0:821; %EV ¼ 67:32;
F ¼ 30:906; p < 0:0000; S:E:E ¼ 0:123; SSY ¼ 2:111;
PRESS ¼ 0:793; q2 ¼ 0:625; SPRESS ¼ 0:133; PSE ¼ 0:127
Figure 2. Structure of 5-N-substituted-2-(substituted benzenesulpho-
nyl)-glutamines used for calculation of ETSA indices.
where DC is the deleted compounds behave as outlier.
The lower value of SPRESS, P.S.E. in eq 7 suggest that the
optimum numbers of variables are taken in the QSAR
model. Deletions of compounds not only increase the
correlation coefficient but also the variance ratio F and
the squared cross-validated correlation coefficient. Thus,
the eq 7 was statistically the best equation. This equation
explains 67.32% of the variances in the activity data. The
correlation matrices of eqs 3 and 7 are presented in
Tables 4 and 5 respectively. The observed, calculated,
residual and predicted residual (Press) values of eq 7 are
shown in Table 6.
implies that carboxyl carbon of the glutamine portion
has the major contribution to the activity of this type of
compounds and higher value of S12 corresponds to the
higher activity. Addition of indicator variable I for the
presence of n-butyl at R5 position (I takes value 1 for
the presence of n-butyl, otherwise zero) increased
explained variance of the equation (2) by about 7% and
the correlation coefficient up to 0.728 in eq 3
LogBA ¼ ꢀ6:227 ðÆ2:307Þ þ 0:382 ðÆ0:0780Þ ꢀMR
þ 0:656 ðÆ0:206Þ S12 þ 0:164 ðÆ0:064Þ I
ð3Þ
3. Discussion
N ¼ 53; R ¼ 0:728; %EV ¼ 53:06; F ¼ 18:463;
p < 0:0000; S:E:E ¼ 0:147; SSY ¼ 2:241;
PRESS ¼ 1:194; q2 ¼ 0:467; SPRESS ¼ 0:156;
PSE ¼ 0:150
The QSAR study of these 53 glutamine analogues showed
that bulky substitutions at benzene ring might possesses
positive contributions to the anticancer activity. Atom
number 12, that is, carboxyl carbon of glutamine may
play as the pharmacophoric atom for the biological
activity. Amongst the different alkyl substitutions at 5-
N-position of glutamine, n-butyl group contributes
more positively towards the activity. The fact behind
this points out the possibility of one of the major inter-
actions may be due to optimum lipophilicity to bind
with the glutamine receptor(s) site(s) of the cancer cells.
Positive coefficient of I indicates that n-butyl substitu-
tion at R5 position is advantageous to the anticancer
activity.
Stepwise deletions of the compounds 13, 33, 47 and 46
which might be acting through a different mechanism of
action help to improve the quality of the relation statis-
tically as follows:
4. Conclusion
LogBA ¼ ꢀ6:452 ðÆ2:231Þ þ 0:373 ðÆ0:075Þ ꢀMR
Our previous studies encourage us to develop structural
variants of glutamine as possible anticancer agents. Thus,
17new compounds were synthesized and characterized by
chemical and instrumental methods. All compounds
were obtained in good yields. These compounds along-
with 36 previously synthesized compounds were bio-
logically evaluated for antitumor activity considering %
þ 0:676 ðÆ0:199ÞS12 þ 0:171ðÆ0:061Þ I
ð4Þ
DC ¼ 13; N ¼ 52; R ¼ 0:744; %EV ¼ 55:32;
F ¼ 19:807; p < 0:0000; S:E:E ¼ 0:142; SSY ¼ 2:154;
PRESS ¼ 1:10; q2 ¼ 0:489; SPRESS ¼ 0:151; PSE ¼ 0:145
Table 4. Correlation matrix of eq 3
LogBA ¼ ꢀ7:260 ðÆ2:201Þ þ 0:381 ðÆ0:073Þ ꢀMR
þ 0:747 ðÆ0:196Þ S12 þ 0:164 ðÆ0:060Þ I
ð5Þ
S12
I
ꢀMR
LogBA
S12
I
ꢀMR
LogBA
1.0000
0.0132
1.0000
0.3126
À0.0077
1.0000
0.4893
0.2535
0.6057
1.0000
DC ¼ 13; 33; N ¼ 51; R ¼ 0:766; %EV ¼ 58:65;
F ¼ 22:225; p < 0:0000; S:E:E ¼ 0:137; SSY ¼ 2:144;
PRESS ¼ 1:015; q2 ¼ 0:526; SPRESS ¼ 0:147; PSE ¼ 0:141
LogBA ¼ ꢀ8:310 ðÆ2:087Þ þ 0:393 ðÆ0:069Þ ꢀMR
Table 5. Correlation matrix of eq 7
þ 0:840 ðÆ0:186Þ S12 þ 0:155 ðÆ0:056Þ I
ð6Þ
S12
I
ꢀMR
LogBA
S12
I
ꢀMR
LogBA
1.0000
0.04670.2644
1.0000
0.5933
DC ¼ 13; 33; 47; N ¼ 50; R ¼ 0:802; %EV ¼ 64:26;
F ¼ 27:565; p < 0:0000; S:E:E ¼ 0:128; SSY ¼ 2:113;
0.0130
1.0000
0.2616
0.6548
1.0000
PRESS ¼ 0:867; q2 ¼ 0:590; SPRESS ¼ 0:137; PSE ¼ 0:132

1418
S. Samanta et al. / Bioorg. Med. Chem. 12 (2004) 1413–1423
Table 6. Observed (obs), calculated (calc), residual (res) and predicted residual (Pres) values of 5-N-Substituted-2- (substituted benzenesulphonyl)-
glutamines on the basis of eq 7
Compda
Obs
Calc
Res
Pres
Compd
Obs
Calc
Res
Pres
5
6
7
8
1.3371.303
1.496
1.020
1.6171.425
1.515
1.658
1.689
1.501
1.792
1.602
1.751
1.621
1.688
1.320
1.488
1.5971.592
1.103
1.282
0.034
0.192
0.038
0.202
31
32
34
35
36
37
38
39
40
41
42
43
44
45
48
49
50
51
52
53
54
55
56
57
1.882
1.856
1.846
919.8971.7
1.828
1.605
1.749
1.495
1.509
1.9071.883
1.791
1.814
1.763
1.798
1.680
1.540
1.615
1.393
1.705
1.532
1.848
1.733
1.814
1.719
1.769
1.882
1.872
0.113
À0.026
À0.026
0.104
0.118
À0.029
À0.029
1.366
1.418
0.130
À0.398
0.140
À0.421
0.098
9
1.550
1.609
1.526
1.642
1.825
1.682
1.786
1.651
1.568
1.459
1.502
À0.035
À0.038
1.829
1.478
1.578
1.641
1.693
À0.001
À0.001
10
11
12
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
0.049
0.163
0.062
0.174
0.127
0.172
0.159
0.190
À0.141
À0.033
À0.080
À0.035
À0.030
0.120
À0.145
À0.040
À0.083
À0.037
À0.036
0.124
À0.146 À0.155
À0.184 À0.192
0.029
0.020
0.013
0.063
0.024
1.771
1.801
1.700
1.740
1.825
1.450
1.514
1.565
1.755
1.643
1.673
1.572
1.716
1.697
0.021
0.014
0.066
À0.139
À0.145
0.058
À0.145
0.060
À0.155
À0.014
À0.015
0.005
0.005
0.090
0.101
0.098
0.106
1.107
1.341
1.382
À0.004
À0.059
À0.064
À0.219
0.064
À0.006
À0.065
À0.070
À0.262
0.070
À0.172
À0.050
À0.111
0.175
0.161
0.098
0.022
À0.176
À0.060
À0.114
0.182
0.165
0.105
0.023
1.318
1.2871.506
1.670
1.821
1.653
1.951
1.625
1.606
1.669
1.721
1.912
1.728
0.152
À0.068
0.160
À0.071
0.039
À0.103
0.048
À0.108
a Compd=Compound.
inhibition of tumor cell count as the activity parameter.
All compounds showed the anticancer activity. In order
to identify the chemical structural features required and/
or responsible for antitumor activity of 5-N-substituted-
2-(substituted benzenesulphonyl) glutamine, Quantitative
Structure–Activity Relationship (QSAR) studies were
performed using both physicochemical and topological
parameters. The QSAR study throws some light on the
further synthesis of better active 5-N-substituted-2-
(substituted benzenesulphonyl) glutamines (QSAR
analogues). In this regard, the most important con-
sideration is the steric influence of benzene ring, which is
conducive to anticancer activity. Increased lipophilicity,
volume and steric bulk of R1, R2, R3 and R4 sub-
stituents correspond to higher value of ꢀMR and hence
result in increase in activity. The required substitution
pattern at the aliphatic moiety is another important
feature to consider for the synthesis of better active
compounds. In aliphatic portion, atom 12 of Figure 2 is
the most important one for the antitumor activity. The
R5 substituents should increase the value of S12 (ETSA
index of atom 12). However, if n-butyl is present at R5
position, steric factor at the benzene ring is only to be
considered for further synthesis of this type of com-
pounds. n-Butyl substitution at aliphatic side chain is
important for antitumor activity may be due to its
optimum lipophilicity.
characterized by IR-, NMR- and Mass spectroscopy as
well as C, H, N analysis.There were two type of sub-
stitutions each in R1, R2, R3 and R4 at aromatic ring
whereas the aliphatic side chain contains nine substitu-
tions at R5 position.
5.1.1. Chemistry. Synthesis was started with chloro-
sulphonation of substitutedbenzenes 1, to get corres-
ponding sulphonyl chlorides 2. This sulphonyl halide
proved to be versatile synthon in the subsequent step in
the preparation of substituted benzenesulphonyl glu-
tamic acids. With the application of Schotton-Bauman
reaction, 2-(substituted benzenesulphonyl) glutamic
acids 3 were prepared by one-step condensation of 2
with l-glutamic acid. In this reaction alkaline medium
was maintained to remove the hydrochloric acid which
was formed during condensation. Reaction of the
resulting intermediates 3 with acetyl chloride afforded
cyclized acid intermediates 1-(substituted benzenesul-
phonyl)-5-oxopyrrolidine-2-carboxylic acids 4. Amino-
lysis of the intermediates 4 with various amines afforded
the corresponding glutamines 5.
5.1.2. General. Melting points were measured on a
capillary melting point apparatus and were uncorrected.
All the compounds were characterized qualitatively and
quantitatively by performing both analytical and spec-
trophotometric analysis. These compounds, which con-
tained free carboxyl groups, were also characterized by
matching neutralization equivalents.
5. Experimental
5.1. Synthesis
The infrared spectra were recorded on BUCK M500
quick scanning Infrared spectrophotometer using KBr
pellets. Running the spectrum of 0.05 mm polystyrene
film did the finer calibration of the machine. The fre-
Seventeen new 5-N-substituted-2-(substituted benzene-
sulphonyl) glutamines were synthesized and chemically

S. Samanta et al. / Bioorg. Med. Chem. 12 (2004) 1413–1423
1419
quencies were expressed in cmÀ1. Proton Nuclear Mag-
netic Resonance (1H NMR) spectra were collected at
25ꢀC in the pulsed Fourier Transformation mode on
Bruker DRX 500 or Bruker DRX 300 MHz spectro-
photometers using the solvents described and was con-
sistent with the proposed structures. Chemical shifts are
reported in d ppm (parts per million) relative to Tetra-
methyl Silane for deuteriorated dimethylsulfoxide
(DMSO-d6). Signals are quoted as s (singlet), d (doub-
let), t (triplet), q (quartet) and m (multiplet). The mass
spectra (FAB) were recorded on JEOL-JMS-SX-PNBA
(p- nitrobenzyl alcohol) was used as matrix (M+) which
showed M+1 peak at 154, 2M+1 peak at 307. Ele-
mental or microanalysis (C, H, N) of the compounds
was performed on 2400 series II CHN analyzer of Per-
kin–Elmer.
taken in 100 mL round bottomed flask, fitted with reflux
condenser and calcium chloride guard tube. Acetyl
chloride (0.025 mol) was added to it and refluxed for 2 h
on boiling waterbath. The completion of the reaction
was tested by thin layer chromatography. After the
reaction was completed, the reaction mixture was
cooled to room temperature and poured onto crushed
ice with continuous stirring. The precipitated product
was filtered and recrystallized from water with charcoal
treatment. Physical data of all intermediates are recor-
ded in Table 1.
5.1.6. Method 4. 5-N-Substituted 2-(substituted benzene-
sulphonyl) glutamines 5–21. In a 50 mL of loosely stop-
pered conical flask, 1-(substituted benzene sulphonyl)-5-
oxopyrrolidine-2- carboxylic acid (4: 0.1 mole) was sus-
pended in 20 mL of water. To this, excess of amines
(0.025 mole) were added and allowed to stand overnight.
The reaction mixture was concentrated over steambath
to remove excess of amines. It was cooled to room
temperature and chilled in an icebath. The mixture was
acidified with 6N hydrochloric acid. The precipitate was
filtered and the residue was washed with cold water and
finally recrystallized from dilute ethanol with charcoal
treatment. Physical data of title compounds were recor-
ded in Table 2.
5.1.3. General synthetic procedure. Method 1. Sub-
stituted benzenesulphonyl chloride (2a–c). To a mixture
of substituted benzene (0.1 mol) in chloroform (50 mL),
in a 500 mL flask equipped with dropping funnel, ther-
mometer, reflux condenser, chlorosulphonic acid (0.25
mol) was added dropwise over a period of 45–60 min.
The reaction mixture was magnetically stirred at 0ꢀC in a
bath containing freezing mixture of ice and salt. Chlor-
osulphonic acid was added in such a rate that the temper-
ature of the reaction mixture does not exceed 5ꢀC. After the
complete addition of chlorosulphonic acid, the reaction
mixture was stirred for another 45 min at room temp-
erature and the mixture was poured on to crushed ice.
The product was extracted with three 50-mL portions of
chloroform, dried overnight over anhydrous sodium
sulphate. Chloroform was distilled off. The product was
sufficiently pure which was not attempted for further
purification. It had been taken for the next step.
5.1.7. 5-N-Methyl-2-(30-nitro benzenesulphonyl) gluta-
mine (5). MS (FAB): M+H+ peak at m/z 346.
1HNMR (300 MHz, DMSO-d6): d 12.70 (s, 1H,
COOH), 8.50 (d, 1H, SO2NH), 8.34 (d, 1H, H-200), 7.98
(dd, 1H, H-60), 7.88 (m, 2H, H-400, H-500), 7.76 (m, 1H,
CONH), 3.78 (m, 1H, H-2), 3.05 (m, 2H, N-CH3-100),
2.02 (m, 2H, H2-4), 1.84 (m, 1H, HA-3), 1.63 (m, 1H,
HB-3). IR (KBr, cmÀ1): 3318, 3114 (N–H str of CONH),
3032 (Ar–C–H str), 2882 (ali C–H str), 1698 (C¼O str),
1564, 1522 (N¼O str of Ar–NO2), 1446 (ali C–H def),
1336 and 1165 (S¼O str of SO2NH), 975, 882 (C–N str
of Ar–NO2), 795 and 750 (Ar–C-H def). Anal.
C12H15N3O7S1 (C, H, N) calcd: 41.74, 4.38, 12.17;
found: 41.45, 4.30, 12.26.
5.1.4. Method 2. 2-(Substituted benzenesulphonyl) gluta-
mic acid (3a–3c). l-glutamic acid (14.7g: 0.1 mol) was
taken in a 250-mL conical flask and sodium hydroxide
solution (2N) was added slowly till all glutamic acid
dissolved and the mixture become distinctly alkaline to
phenolphthalein. The reaction mixture was stirred on a
magnetic stirrer and the temperature was maintained at
70ꢀC using hot water-bath. Substituted benzenesulpho-
nyl chloride (2: 0.15 moles) was added in small portions
with constant stirring and sodium hydroxide (2N) was
added time-to-time to keep the reaction mixture
alkaline. The reaction was continued until a clear
homogeneous solution resulted and thin layer chroma-
tography showed the reaction was complete. After the
reaction was over, it was allowed to cool to room
temperature and filtered to separate undissolved solid
matter, if any. The filtrate was acidified with con-
centrated hydrochloric acid and saturated with sodium
chloride. The product was extracted with three 50 mL
portions of ethyl acetate. Ethyl acetate layer was
washed with brine solution (15 mL) and dried overnight
over anhydrous sodium sulphate. The solvent was dis-
tilled off to get the desired diacid (3a–c).
5.1.8. 5-N-Ethyl-2-(30-nitro benzenesulphonyl) glutamine
1
(6). MS (FAB): M+H+ peak at m/z 360. H NMR
(300 MHz, DMSO-d6): d 12.72 (s, 1H, COOH), 8.48 (d,
1H, SO2NH), 8.32 (d, 1H, H-20), 7.94 (dd, 1H, H-60),
7.85 (m, 2H, H-40, H-50), 7.76 (m, 1H, CONH), 3.81 (m,
1H, H-2), 3.02 (m, 2H, N-CH2-100), 2.08 (m, 2H, H2-4),
1.88 (m, 1H, HA-3), 1.65 (m, 1H, HB-3), 0.99 (m, 3H,
CH3-200). IR (KBr, cmÀ1): 3320, 3110 (N–H str of
CONH), 3028 (Ar–C–H str), 2885 (ali C–H str), 1702
(C¼O str), 1563, 1520 (N¼O str of Ar–NO2), 1442 (ali
C–H def), 1334 and 1164 (S¼O str of SO2NH), 973, 880
(C–N str of Ar–NO2), 798 and 754 (Ar–C–H def). Anal.
C13H17N3O7S1 (C, H, N) calcd: 43.45, 4.77, 11.69;
found: 43.38, 4.62, 11.52.
5.1.9. 5-N-n-Propyl-2-(30-nitro benzenesulphonyl) gluta-
mine (7). MS (FAB): M+H+ peak at m/z 374.1H
NMR (300 MHz, DMSO-d6): d 12.69 (s, 1H, COOH),
0
5.1.5. Method 3. 1-(Substituted benzenesulphonyl)-5-oxo-
pyrrolidine-2-carboxylic acid (4a–4c). 2-(Substituted
benzenesulphonyl) glutamic acid (3: 0.01 mol) was
8.45 (d, 1H, SO2NH), 8.37(d, 1H, H-2 ), 7.88 (dd, 1H,
H-60), 7.80 (m, 2H, H-40, H-50), 7.72 (m, 1H, CONH),
3.78 (m, 1H, H-2), 3.06 (m, 2H, N-CH2-100), 2.10 (m,

1420
S. Samanta et al. / Bioorg. Med. Chem. 12 (2004) 1413–1423
2H, H2-4), 1.92 (m, 1H, HA-3), 1.69 (m, 1H, HB-3), 1.28
(m, 2H, CH2-200), 0.97(m, 3H, CH 3-300). IR (KBr,
cmÀ1): 3322, 3105 (N–H str of CONH), 3032 (Ar–C–H
str), 2890 (ali C–H str), 1698 (C¼O str), 1564, 1525
(N¼O str of Ar–NO2), 1446 (ali C–H def), 1336 and 1166
(S¼O str of SO2NH), 973, 882 (C–N str of Ar–NO2),
796 and 755 (Ar–C–H def). Anal. C14H19N3O7S1 (C, H,
N) calcd: 45.03, 5.13, 11.25; found: 45.25, 5.03, 11.09.
CH2-500), 0.85 (m, 3H, CH3-600). IR (KBr, cmÀ1): 3325,
3114 (N–H str of CONH), 3032 (Ar–C–H str), 2887(ali
C–H str), 1708 (C¼O str), 1566, 1522 (N¼O str of Ar–
NO2), 1446 (ali C–H def), 1337and 1166 (S ¼O str of
SO2NH), 975, 882 (C–N str of Ar–NO2), 795 and 750
(Ar–C–H def). Anal. C17H25N3O7S1 (C, H, N) calcd:
49.15, 6.07, 10.11; found: 49.03, 5.96, 10.26.
5.1.14. 5-N-i-Propyl-2-(20-chloro-50-methyl benzenesul-
phonyl) glutamine (12). MS (FAB): M+H+ peak at m/
z 377. ‘p1HNMR (300 MHz, DMSO-d6): d 12.74 (s, 1H,
COOH), 8.50 (d, 1H, SO2NH), 8.20–8.06 (m, 2H, H-30,
H-60), 7.82 (m, 1H, H-40), 7.72 (m, 1H, CONH), 3.78m,
1H, H-2), 3.00 (m, 1H, N–CH–100), 2.62 (s, 3H, Ar–
CH3), 2.08 (m, 2H, H2-4), 1.86 (m, 1H, HA-3), 1.67(m,
1H, HB-3), 0.95 (m, 6H, CH3-200, CH3-300). IR (KBr,
cmÀ1): 3316, 3105 (N–H str of CONH), 3024 (Ar–C–H
str), 2882 (ali C–H str), 1698 (C¼O str), 1560, 1516
(N¼O str of Ar–NO2), 1438 (ali C–H def), 1332 and 1160
(S¼O str of SO2NH), 975, 882 (C–N str of Ar–NO2),
796 and 750 (Ar–C–H def). Anal. C15H21N2O5S1Cl (C,
H, N) calcd: 47.81, 5.62, 7.43; found: 47.56, 5.37, 7.37.
5.1.10. 5-N-i-Propyl-2-(30-nitro benzenesulphonyl) gluta-
mine (8). MS (FAB): M+H+ peak at m/z 374. 1H
NMR (300 MHz, DMSO-d6): d 12.66 (s, 1H, COOH),
8.50 (d, 1H, SO2NH), 8.35 (d, 1H, H-20), 7.96 (dd, 1H,
H-60), 7.89 (m, 2H, H-40, H-50), 7.72 (m, 1H, CONH),
3.84 (m, 1H, H-2), 3.00 (m, 1H, N-CH-100), 2.10 (m, 2H,
H2-4), 1.90 (m, 1H, HA-3), 1.67(m, 1H, H B-3), 1.10–
0.90 (m, 6H, CH3-200, CH3-300). IR (KBr, cmÀ1): 3325,
3112 (N–H str of CONH), 3030 (Ar–C–H str), 2882 (ali
C–H str), 1700 (C¼O str), 1565, 1523 (N¼O str of Ar–
NO2), 1445 (ali C–H def), 1332 and 1162 (S¼O str of
SO2NH), 970, 882 (C–N str of Ar–NO2), 794 and 750
(Ar–C–H def). Anal. C14H19N3O7S1 (C, H, N) calcd:
45.03, 5.13, 11.25; found: 45.15, 5.20, 11.14.
5.1.15. 5-N-n-Propyl-2-(20-chloro-50-methyl benzenesul-
phonyl) glutamine (13). MS (FAB): M+H+ peak at m/z
377. ‘p1HNMR (300 MHz, DMSO-d6): d 12.70 (s, 1H,
COOH), 8.44 (d, 1H, SO2NH), 8.16–8.00 (m, 2H, H-30,
H-60), 7.78 (m, 1H, H-40), 7.64 (m, 1H, CONH), 3.81
(m, 1H, H-2), 3.05 (m, 2H, N–CH2–100), 2.66 (s, 3H, Ar–
CH3), 2.10 (m, 2H, H2-4), 1.82 (m, 1H, HA-3), 1.65 (m,
1H, HB-3), 1.28 (m, 2H, CH2-200), 0.92 (m, 3H, CH3-300).
IR (KBr, cmÀ1): 3322, 3110 (N–H str of CONH), 3018
(Ar–C–H str), 2878 (ali C–H str), 1702 (C¼O str), 1556,
1512 (N¼O str of Ar–NO2), 1444 (ali C–H def), 1336
and 1165 (S¼O str of SO2NH), 977, 885 (C–N str
of Ar–NO2), 798 and 754 (Ar–C–H def). Anal.
C15H21N2O5S1Cl (C, H, N) calcd: 47.81, 5.62, 7.43;
found: 47.68, 5.49, 7.39.
5.1.11. 5-N-Phenyl-2-(30-nitro benzenesulphonyl) gluta-
mine (9). MS (FAB): M+H+ peak at m/z 408.
1HNMR (300 MHz, DMSO-d6): d 12.74 (s, 1H,
0
COOH), 8.54 (d, 1H, SO2NH), 8.37(d, 1H, H-2 ), 7.98
(dd, 1H, H-60), 7.88 (m, 2H, H-40, H-50), 7.78 (m, 5H,
ph. protons), 7.64 (m, 1H, CONH), 3.85 (m, 1H, H-2),
2.12 (m, 2H, H2-4), 1.92 (m, 1H, HA-3), 1.69 (m, 1H,
HB-3). IR (KBr, cmÀ1): 3316, 3106 (N–H str of CONH),
3032 (Ar–C–H str), 2882 (ali C–H str), 1695 (C¼O str),
1565, 1524 (N¼O str of Ar–NO2), 1444 (ali C–H def),
1336 and 1165 (S¼O str of SO2NH), 977, 884 (C–N str
of Ar–NO2), 800 and 756 (Ar–C–H def). Anal.
C17H17N3O7S1 (C, H, N) calcd: 50.12, 4.21, 10.31;
found: 49.95, 4.11, 10.22.
5.1.12. 5-N-n-Butyl-2-(30-nitro benzenesulphonyl) gluta-
mine (10). MS (FAB): M+H+ peak at m/z 388. 1H
NMR (300 MHz, DMSO-d6): d 12.68 (s, 1H, COOH),
8.42 (d, 1H, SO2NH), 8.26 (d, 1H, H-20), 7.90 (dd, 1H,
H-60), 7.80 (m, 2H, H-40, H-50), 7.74 (m, 1H, CONH),
3.76 (m, 1H, H-2), 3.00 (m, 2H, N-CH2-100), 2.12 (m,
2H, H2-4), 1.92 (m, 1H, HA-3), 1.70 (m, 1H, HB-3), 1.38
(m, 2H, CH2-200), 1.20 (m, 2H, CH2-300), 0.88 (m, 3H,
CH3-400). IR (KBr, cmÀ1): 3322, 3114 (N–H str of
CONH), 3034 (Ar–C–H str), 2888 (ali C–H str), 1705
(C8O str), 1565, 1524 (N¼O str of Ar–NO2), 1446 (ali
C–H def), 1335 and 1165 (S¼O str of SO2NH), 977, 884
(C–N str of Ar–NO2), 794 and 752 (Ar–C–H def). Anal.
C15H21N3O7S1 (C, H, N) calcd: 46.50, 5.46, 10.85;
found: 46.32, 5.50, 10.76.
5.1.16. 5-N-n-Butyl-2-(20-chloro-50-methyl benzenesul-
phonyl) glutamine (14). MS (FAB): M+H+ peak at m/
z 391. H NMR (300 MHz, DMSO-d6): d 12.72 (s, 1H,
1
COOH), 8.46 (d, 1H, SO2NH), 8.22–8.04 (m, 2H, H-30,
H-60), 7.84 (m, 1H, H-40), 7.68 (m, 1H, CONH), 3.76
(m, 1H, H-2), 3.02 (m, 2H, N-CH2-100), 2.70 (s, 3H, Ar–
CH3), 2.12 (m, 2H, H2-4), 1.86 (m, 1H, HA-3), 1.69 (m,
1H, HB-3), 1.45–1.25 (m, 4H, CH2-200, CH2-300), 0.95 (m,
3H, CH3-400). IR (KBr, cmÀ1): 3318, 3107(N–H str of
CONH), 3020 (Ar–C–H str), 2884 (ali C–H str), 1708
(C¼O str), 1560, 1516 (N¼O str of Ar–NO2), 1442 (ali
C–H def), 1334 and 1164 (S¼O str of SO2NH), 975, 882
(C–N str of Ar–NO2), 796 and 752 (Ar–C–H def). Anal.
C16H23N2O5S1Cl (C, H, N) calcd: 49.16, 5.93, 7.17;
found: 48.97, 5.82, 7.07.
5.1.13. 5-N-n-Hexyl-2-(30-nitro benzenesulphonyl) gluta-
mine (11). MS (FAB): M+H+ peak at m/z 416.
‘p1HNMR (300 MHz, DMSO-d6): d 12.66 (s, 1H,
COOH), 8.54 (d, 1H, SO2NH), 8.38 (d, 1H, H-20), 7.98
(dd, 1H, H-60), 7.88 (m, 2H, H-40, H-50), 7.79 (m, 1H,
CONH), 3.85 (m, 1H, H-2), 3.08 (m, 2H, N–CH2–100),
2.10 (m, 2H, H2-4), 1.90 (m, 1H, HA-3), 1.68 (m, 1H,
HB-3), 1.55–1.10 (m, 8H, CH2-200, CH2-300, CH2-400,
5.1.17. 5-N-i-Butyl-2-(20-chloro-50-methyl benzenesulpho-
nyl) glutamine (15). MS (FAB): M+H+ peak at m/z
391. 1HNMR (300 MHz, DMSO-d6): d12.68 (s, 1H,
COOH), 8.50 (d, 1H, SO2NH), 8.25–8.10 (m, 2H, H-30,
H-60), 7.88 (m, 1H, H-40), 7.72 (m, 1H, CONH), 3.82
(m, 1H, H-2), 3.06 (m, 2H, N-CH2-100), 2.72 (s, 3H, Ar–
CH3), 2.16 (m, 2H, H2-4), 1.90 (m, 1H, HA-3), 1.70 (m,
1H, HB-3), 1.45 (m, 1H, CH-200), 1.15-0.95 (m, 6H, CH3-

S. Samanta et al. / Bioorg. Med. Chem. 12 (2004) 1413–1423
1421
300, CH3-400). IR (KBr, cmÀ1): 3322, 3110 (N–H str of
CONH), 3015 (Ar–C–H str), 2876 (ali C–H str), 1700
(C¼O str), 1558, 1514 (N¼O str of Ar–NO2), 1446 (ali
C–H def), 1336 and 1164 (S¼O str of SO2NH), 973, 880
(C–N str of Ar–NO2), 794 and 748 (Ar–C–H def). Anal.
C16H23N2O5S1Cl (C, H, N) calcd: 49.16, 5.93, 7.17;
found: 48.88, 5.78, 7.12.
(C¼O str), 1567, 1524 (N¼O str of Ar–NO2), 1446 (ali
C–H def), 1332 and 1160 (S¼O str of SO2NH), 977, 884
(C–N str of Ar–NO2), 798 and 754 (Ar–C–H def). Anal.
C14H19N2O5S1Br (C, H, N) calcd: 41.29, 4.70, 6.88;
found: 40.96, 4.65, 6.76.
5.1.22. 5-N-i-Butyl-2-(40-bromo benzenesulphonyl) gluta-
mine (20). MS (FAB): M+H+ peak at m/z 422. 1H
NMR (300 MHz, DMSO-d6): d 12.72 (s, 1H, COOH),
8.52 (d, 1H, SO2NH), 8.32–7.96 (m, 4H, H-2, H-30, H-
50, H-60), 7.78 (m, 1H, CONH), 3.72 (m, 1H, H-2), 2.98
(m, 1H, N-CH-100), 2.02 (m, 2H, H2-4), 1.86 (m, 1H,
HA-3), 1.64 (m, 1H, HB-3), 1.15–0.99 (m, 6H, CH3-200,
CH3-300). IR (KBr, cmÀ1): 3324, 3116 (N–H str of
CONH), 3028 (Ar–C–H str), 2876 (ali C–H str), 1700
(C¼O str), 1564, 1520 (N¼O str of Ar–NO2), 1442 (ali
C–H def), 1334 and 1162 (S¼O str of SO2NH), 973, 881
(C–N str of Ar–NO2), 794 and 748 (Ar–C–H def). Anal.
C15H21N2O5S1Br (C, H, N) calcd: 42.76, 5.02, 6.65;
found: 42.25, 5.11, 6.48.
5.1.18. 5-N-Benzyl-2-(20-chloro-50-methyl benzenesulpho-
nyl) glutamine (16). MS (FAB): M+H+ peak at m/z
1
425. HNMR (300 MHz, DMSO-d6): d 12.74 (s, 1H,
COOH), 8.52 (d, 1H, SO2NH), 8.22–8.12 (m, 2H, H-30,
H-60), 7.90–7.80 (m, 6H, H-40, ph.-protons), 7.74 (m,
1H, CONH), 4.20 (m, 2H, CH2-ph), 3.80 (m, 1H, H-2),
2.72 (s, 3H, Ar-CH3), 2.16 (m, 2H, H2-4), 1.90 (m, 1H,
HA-3), 1.70 (m, 1H, HB-3). IR (KBr, cmÀ1): 3320, 3110
(N–H str of CONH), 3018 (Ar–C–H str), 2880 (ali C–H
str), 1705 (C¼O str), 1556, 1510 (N¼O str of Ar–NO2),
1442 (ali C–H def), 1334 and 1162 (S¼O str of SO2NH),
977, 884 (C–N str of Ar–NO2), 798 and 752 (Ar–C–H
def). Anal. C19H21N2O5S1Cl (C, H, N) calcd: 53.71,
4.98, 6.59; found: 53.45, 4.79, 6.42.
5.1.23. 5-N-Phenyl-2-(40-bromo benzenesulphonyl) gluta-
mine (21). MS (FAB): M+H+ peak at m/z 442. 1H
NMR (300 MHz, DMSO-d6): d 12.68 (s, 1H, COOH),
8.48 (d, 1H, SO2NH), 8.22–7.92 (m, 4H, H-20, H-30, H-
50, H-60), 7.76 (m, 5H, ph.-protons), 7.64 (m, 1H,
CONH), 3.76 (m, 1H, H-2), 2.10 (m, 2H, H2-4), 1.92 (m,
1H, HA-3), 1.65 (m, 1H, HB-3). IR (KBr, cmÀ1): 3320,
3110 (N–H str of CONH), 3034 (Ar–C–H str), 2878 (ali
C–H str), 1702 (C¼O str), 1564, 1520 (N¼O str of Ar–
NO2), 1446 (ali C–H def), 1336 and 1164 (S¼O str of
SO2NH), 977, 884 (C–N str of Ar–NO2), 798 and 752
(Ar–C–H def). Anal. C17H17N2O5S1Br (C, H, N) calcd:
46.27, 3.88, 6.35; found: 46.08, 3.75, 6.26.
5.1.19. 5-N-n-Butyl-2-(40-bromo benzenesulphonyl) gluta-
mine (17). MS (FAB): M+H+ peak at m/z 422. 1H
NMR (300 MHz, DMSO-d6): d 12.70 (s, 1H, COOH),
8.50 (d, 1H, SO2NH), 8.26–7.94 (m, 4H, H-20, H-30, H-
50, H-60), 7.74 (m, 1H, CONH), 3.78 (m, 1H, H-2), 3.05
(m, 2H, N–CH2-100), 2.10 (m, 2H, H2-4), 1.90 (m, 1H,
HA-3), 1.68 (m, 1H, HB-3), 1.35-1.15 (m, 4H, CH2-200,
CH2-300), 0.95 (m, 3H, CH3-400). IR (KBr, cmÀ1): 3322,
3114 (N–H str of CONH), 3032 (Ar–C–H str), 2880 (ali
C–H str), 1705 (C¼O str), 1565, 1522 (N¼O str of Ar–
NO2), 1444 (ali C–H def), 1335 and 1164 (S¼O str of
SO2NH), 975, 882 (C–N str of Ar–NO2), 796 and 750
(Ar–C–H def). Anal. C15H21N2O5S1Br (C, H, N) calcd:
42.76, 5.02, 6.65; found: 42.58, 4.89, 6.51.
5.2. Pharmacology
Fifty-three 5-N-substituted-2-(substituted benzenesul-
phonyl) glutamines (5–57) were biologically evaluated
for their possible antitumor activity in search of poten-
tial anticancer agents.
5.1.20. 5-N-n-Hexyl-2-(40-bromo benzenesulphonyl) glu-
1
tamine (18). MS (FAB): M+H+ peak at m/z 450. H
NMR (300 MHz, DMSO-d6): d 12.74 (s, 1H, COOH),
8.53 (d, 1H, SO2NH), 8.28–7.98 (m, 4H, H-20, H-30, H-
50, H-60), 7.77 (m, 1H, CONH), 3.81 (m, 1H, H-2), 3.00
(m, 2H, N–CH2-100), 2.06 (m, 2H, H2-4), 1.88 (m, 1H,
HA-3), 1.70 (m, 1H, HB-3), 1.38–1.20 (m, 8H, CH2-200,
CH2-300, CH2-400, CH2-500), 0.99 (m, 3H, CH3-600). IR
(KBr, cmÀ1): 3318, 3110 (N–H str of CONH), 3028
(Ar–C–H str), 2878 (ali C–H str), 1698 (C¼O str), 1560,
1518 (N¼O str of Ar–NO2), 1440 (ali C–H def), 1336
and 1162 (S¼O str of SO2NH), 973, 878 (C–N str
of Ar–NO2), 795 and 752 (Ar–C–H def). Anal.
C17H25N2O5S1Br (C, H, N) calcd: 95.44, 5.61, 6.23;
found: 95.16, 5.33, 6.26.
5.2.1. Tumor cells. EAC (Ehrlich Ascites Carcinoma)
cells originated from human breast carcinoma by spon-
taneous passaging. It is an undifferentiated tumor,
which has lost its epithelial character. On subcutaneous
inoculation it grows in the form of solid nodes and upon
intraperitoneal inoculation ascites rich tumor cells will
be produced. EAC were maintained in vivo in Swiss
Albino mice by passaging every 10 days. EAC cells of 9
days old were used for the screening of the entire final
compounds 5–57.
5.2.2. Animals. Female Swiss albino mice of 10 weeks
old with an average body weight of 18–20 grams were
used. All mice were kept on basal metabolic diet with
water ad libitum.
5.1.21. 5-N-n-Propyl-2-(40-bromo benzenesulphonyl) glu-
1
tamine (19). MS (FAB): M+H+ peak at m/z 408. H
NMR (300 MHz, DMSO-d6): d 12.68 (s, 1H, COOH),
8.54 (d, 1H, SO2NH), 8.24–7.94 (m, 4H, H-20, H-30, H-
50, H-60), 7.76 (m, 1H, CONH), 3.77 (m, 1H, H-2), 3.02
(m, 2H, N-CH2-100), 2.08 (m, 2H, H2-4), 1.92 (m, 1H,
HA-3), 1.66 (m, 1H, HB-3), 1.32 (m, 2H, CH2-200), 0.96
(m, 3H, CH3-300). IR (KBr, cmÀ1): 3320, 3114 (N–H str
of CONH), 3034 (Ar–C–H str), 2832 (ali C–H str), 1700
5.2.3. Screening procedure. Two groups of Swiss Albino
Mice, each containing 5 healthy mice of the same sex
(female in this case), approximately of the same age
and body weight (18–20 g), were selected at random and
kept in two different cages under identical conditions.

1422
S. Samanta et al. / Bioorg. Med. Chem. 12 (2004) 1413–1423
One of these two groups served as control while the
other as test. Ehrlich Ascites Carcinoma (EAC) cells
were collected from the donor mice and were suspended
in sterile isotonic solution (0.9% w/v NaCl). The numbers
of tumor cells per mL of this suspension were counted
under microscope with the help of haemocytometer. A
definite number (about 2Â106 cells/0.2 mL) of these living
viable cells was injected or implanted into the peritoneal
cavity of each mouse. In this instance, the tumor cells
multiplied relatively freely within the peritoneal cavity
and ascites developed. A day of incubation was allowed
to establish the disease in the body before starting the
drug administration. From the second day of trans-
plantation up to the eighth day a suitable challenge dose
(0.2 mmole/kg body weight) of the drug solution/sus-
pension in sterile phosphate buffer (pH 7.2) was injected
intraperitoneally to each mouse in the test group at 24
hr interval. Thus, seven doses of the drug were admi-
nistered to each mouse in the test group. On the ninth
day food and water was withheld 18 hr before the
starting of the testing operation. The weights of all
the animals were recorded before they were sacrificed. The
peritoneal cavity was dissected and by a syringe
the ascitic fluid was withdrawn to a suitable volume,
collected in sterile ice-cold saline and preserved in ice
bath. The total number of living cells/mL in the perito-
neal fluid of the 5 mice in a group was calculated. The
fluid was sucked by adsorbent cotton. The weight of
the 5 mice after sacrifice was recorded.
value, and E-state index and indicator parameter I for
the presence of n-butyl group at R5 position are recor-
ded in Table 3.
5.3.2. Statistical analysis. Correlation analysis and mul-
tiple regression analysis33À37 were carried out using
software ‘Multiregress’ developed in our laboratory.32
By the correlation analysis intercorrelated parameters
were eliminated stepwise depending on their individual
correlation with the biological activity. Correlation
matrices are given in Tables 4 and 5 respectively.
Antitumor activity of the compounds was subjected to
multiple regression analysis and the statistical quality of
the equations was justified38 by parameter like correlation
coffiecient (r or R), standard error of the estimate (S.E.E),
variance ratio (F) at specified degree of freedom (df).
5.3.3. QSAR validation. For the validation of the QSAR
equation39,40 PRESS, q2, SPRESS, PSE were used to
predicting the activity of the compounds in the test set.
Acknowledgements
The work was supported by the funding from a Minor
Research Project of Jadavpur University (JU), Kolkata
under the Unassigned Grant of University Grants
Commission (UGC), New Delhi.
The evaluation of the test drug was made by comparing
the cell count of the test with that of the control.
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Percentage inhibition of Ascitic cells ðTCIÞ ¼
ð1 ꢀ T=CÞ ꢁ 100
where T is the average number of Ascitic cells/mL in
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