Synthesis and antibacterial activity of some novel 4-benzyl-piperazinyl-s- triazine derivatives

Article abstract of DOI:10.14233/ajchem.2013.12884

Considerable interest has been attracted in s-triazine scaffold and its derivatives because of their large variety of pharmacological activities. In this project, a series of 4-benzyl-piperazinyl-s-triazine derivatives 5a to 5j were synthesized by three steps substitution reaction of cyanuric chloride with various nucleophilic compounds in presence of a base. Molecular structures of the synthesized compounds were elucidated by FTIR, 1H NMR, 13C NMR, MS spectral data and elemental analyses. The in vivo antibacterial activity was evaluated by broth dilution method against representative four Gram-positive and four Gram-negative bacterial strains. Many compounds have displayed comparable better antibacterial activity against Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermis and Pseudomonas aeruginosa with reference to streptomycin.

Full text of DOI:10.14233/ajchem.2013.12884

Asian Journal of Chemistry; Vol. 25, No. 1 (2013), 186-190
http://dx.doi.org/10.14233/ajchem.2013.12884
Synthesis and Antibacterial Activity of Some Novel 4-Benzyl-piperazinyl-s-triazine Derivatives
*
S. JANA and A. DAS
Department of Pharmaceutical Science, Dibrugarh University, Dibrugarh-786 004, India
*Corresponding author: E-mail: janasrabanti@gmail.com
(Received: 18 October 2011;
Accepted: 16 July 2012)
AJC-11845
Considerable interest has been attracted in s-triazine scaffold and its derivatives because of their large variety of pharmacological activities.
In this project, a series of 4-benzyl-piperazinyl-s-triazine derivatives 5a to 5j were synthesized by three steps substitution reaction of
cyanuric chloride with various nucleophilic compounds in presence of a base. Molecular structures of the synthesized compounds were
1
elucidated by FTIR, H NMR, 13C NMR, MS spectral data and elemental analyses. The in vivo antibacterial activity was evaluated by
broth dilution method against representative four Gram-positive and four Gram-negative bacterial strains. Many compounds have displayed
comparable better antibacterial activity against Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermis and Pseudomonas
aeruginosa with reference to streptomycin.
Key Words: Antibacterial, s-Triazine, MIC, Zone of inhibition, Cyanuric chloride.
antifungal27 and also possess potent antibacterial activity28-32
.
INTRODUCTION
Many of the piperazine ring containing compounds exhibited
the antibacterial activities33,34. Herein, we report the synthesis
and antibacterial activity of a variety of 4-benzyl-piperaziyl-
s-triazine derivatives.
The pathogens rapidly develop the resistance to most of the
known antibiotics and create a serious health problem1-3. Coupled
with mounting bacterial resistance, an aging population and a
dearth of novel therapeutics, there is an important unmet clinical
need to develop new antibiotics4,5. In view of the above, the
design and synthesis of effective and potent antimicrobials is
EXPERIMENTAL
Synthetic methods adopted for making compounds 5a to
5j are illustrated in Scheme-I. Synthesis of s-triazine derivatives
were performed by means of nucleophilic displacement35 of
three chlorine atoms of cyanuric chloride (1) by thee nucleo-
philes by three steps in which one common nucleophile was
benzyl piperazine and other two nucleophiles were different.
According to this, compounds 3a-f was obtained by treating
equimolecular various nucleophile (2a-f) with cyanuric
chloride (1). The compounds 4a-f was synthesized by treating
equimolecular 3a-f with various other nucleophiles, R2-H
(Table-1) and finally compounds 5a-f were obtained by treating
equimolecular 4a-f with 1-benzyl-piperazine.
an area of immense significance for medicinal chemistry1-12
.
A considerable part of research carried out in the development
of new drugs is devoted to the study of heterocyclic compound.
There are vast numbers of pharmacologically active nitrogen
containing heterocyclic compound. Among them s-triazine
scaffold is of immense importance. Substituted s-triazine deri-
vatives have become attractive targets for medicinal chemistry
due to its potent biological activity such as antiprotozoal13,
anticancer14-16, estrogen receptor modulators17, antimalarial18-21
,
cyclin-dependent kinase inhibitors22, antiviral23, vascular
inflammatory disease24, CNS depressant25, antitubercular26,
HN
Cl
N
R
1
R2
Cl
N
Cl
R2
N
Cl
N
R2-H
Acetone
6
R1-H
N
N
0-50 temp
for 1-2 h
N
N
N
N
N
N
N
1,4-Dioxane
1,4-Dioxane
40-500 temp
for 4-5 h
N
N
Reflux at
90-1100C temp
2a-f
Cl
Cl
R
1
for 7-8 h
3a-f
5a-j
1
R1
4a-j
Scheme-I

Vol. 25, No. 1 (2013)
Synthesis and Antibacterial Activity of Some Novel 4-Benzyl-piperazinyl-s-triazine Derivatives 187
TABLE-1
R2
N
N
N
N
N
R1
Compound
5a
R1
R2
m.f.a
m.p. (ºC)
217-220
Yield (%)
76.86
HN
NO2
N
C24H30N8O2
N
N
N
5b
5c
C23H32N8
254-257
140-142
54.86
78.86
C30H37N7
N
HN
O
NO2
N
5d
5e
C24H27N7O4
C23H22N8O3
310-312
252-254
69.86
57.86
O
N
O
NO2
N
HN
NO2
HN
NO2
O
5f
C26H25N9O4
C22H31N7O2
240-243
264-266
64.86
67.86
N
N
5g
O
S
N
N
5h
C26H24N10O2S
212-214
76.86
N
N
H
NO2
N
5i
5j
N
C24H39N7
C28H33N9
184-186
265-267
78.96
48.74
N
N
N
N
aElemental analyses for C, H and N were within 0.4% of the theoretical values
Synthetic procedure: All the compounds (5a to 5i) were
Synthesis of 4,6-bis-(substituted)-2-(4-benzyl-piperazin-
synthesized using synthetic grade chemicals and further purifi-
cation also carried out for some chemicals and solvents.
Synthesis of monosubstituted 2,4-dichloro-s-triazine
(3a-f)35,36: Cyanuric chloride (0.01 M) was dissolved in acetone
(25 mL) and different nucleophilic compounds 2a-f (R1-H)
as show in Table-1 (0.01 M) was added to it at 0-5 ºC tempe-
rature and stirred for 1-2 h, in presence 10 % sodium carbonate
solution. Ice water was poured into reaction mixture. The solid
was separated out, washed with distilled water and recrystallized.
Synthesis of disubstituted 2-chloro-s-triazine (4a-j):A
mixture of 3a-f (0.01 M) and different nucleophilic compounds
(R2-H) as show in Table-1 (0.01 M) were dissolved in 1,4-
dioxane (50 mL) and stirred at 40-50 ºC temperature for 4-5
h, in presence 10 % sodium carbonate solution. Ice water was
poured into reaction mixture. The solid separated out, washed
with distilled water and recrystallized
1-yl)-s-triazine derivatives (5a-f): A mixture of 4a-j (0.01
M) and 1-benzyl piperazine (0.01 M) were dissolved in 1,4-
dioxane (50 mL) and the reaction mixture was refluxed at 90-
110 ºC for 7-8 h, in presence 10 % sodium carbonate solution.
Ice water was poured into reaction mixture. The solid separated
out, washed with distilled water and recrystallized. The final
product was finally purified by column chromatography.
All the synthesized compounds (Table-1) were charac-
terized by spectroscopic data as 1H NMR, 13C NMR, FT-IR,
mass and elemental analysis.
Melting point of the synthesized compounds was deter-
mined on Veego melting point apparatus. IR spectra were
obtained on Perkin Elmer, spectrum RX-I, infrared spectro-
1
meter. H NMR spectra were recorded on Bruker Avance II
(300.40 MHz) spectrometer and 13C NMR on Bruker Avance
II (100 MHz) spectrometer in DMSO-d6 and CDCl3. The mass

188 Jana et al.
Asian J. Chem.
spectra were recorded on TOF mass spectrophotometer.
Elemental analysis was performed using a Perkin Elmer CHN-
OS analyzer.
128.9, 128.5, 127.3,122.2, 122.1 (C-Ar), 60.1 (-CH2-), 52.2,
50.0 (-CH2-), 66.4, 46.3 (-CH2-), 44.7 (-CH2-), 13.0 (-CH3);
MS (m/e): 477.23 [M+].
6-(4-Benzylpiperazin-1-yl)-N2,N2-diethyl-N4-(4-
nitrophenyl)-1,3,5-triazine-2,4-diamine(5a): Brownish
yellow; IR (KBr, νmax, cm-1): 3349 (N-Hstretch, >NH), 3092
(C-Hstretch,Ar), 2971 (C-Hstretch), 2362 (C-Nstretch, s-triazine), 1621
2-(4-Benzylpiperazin-1-yl)-4-(1H-imidazol-1-yl)-6-(4-
nitro-phenoxy)-1,3,5-triazine(5e): Brownish Yellow; IR
(KBr, νmax, cm-1): 3090 (C-Hstretch, Ar), 2981 (C-Hstretch), 2354,
2362 (C-Nstretch), 1557, 1454 (C-Cstretch, Ar); 1304, 1229
(C-Nstretch), 1105 (C-Nstretch), 1383 (C-Hben), 807 (C-Hbend, Ar);
1H NMR (300 MHz, DMSO-d6): δ 8.057,7.496, 7.251(t, 3H,
Ar-H), 7.677, 7.158 (d, 2H, Ar-H), 7.370, 7.344, 7.318 (t,
5H,Ar-H) 3.799 (s, 2H, J = 14.80, -CH2-), 3.548 (s, 2H, J =
15.92, -CH2-), 2.447 (s, 2H, J = 1.0, -CH2-); 13C NMR (100
MHz, DMSO-d6): δ 182.3, 180.4, 174.8 (C of s-triazine), 161.3,
135.6 (C-Ar), 134.5, 128.9, 128.5, 127.8,127.3, 122.2, 122.1,
114.7 (-CH-), 60.1 (-CH2-), 52.2, 50.0 (-CH2-); MS (m/e):
458.47 [M+].
(N-Hbend), 1601, 1500 (C-Cstretch, Ar), 1550, 1431 (N-Ostretch
,
-NO2), 1374 (C-Hbend), 1318, 1250 (C-Nstretch, Ar), 1178
(C-Nstretch), 849 (C-Hbend,Ar); 1H NMR (300 MHz, DMSO-d6):
δ 7.788 (s, 2H, J = 1.00, Ar-H), 6.790 (s, 2H, J = 1.26, Ar-H),
7.323, 7.283, 7.070 (t, 5H, J = 10.69, Ar-H), 4.654 (s, 1H, J =
6.00, -NH), 3.652 (s, 2H, J = 1.51, -CH2-), 3.171 (s, 4H, J =
1.51, -CH2-), 3.106 (s, 4H, J = 12.06, -CH2-), 2.594 (s, 4H, J =
3.04, -CH2-), 1.097 (s, 6H, J = 9.08, -CH3); 13C NMR (100
MHz, DMSO-d6): δ 182.4, 179.2, 159.4 (C of s-triazine), 138.4,
135.6 (Ar-C), 128.9, 128.5, 127.3, 121.9 (Ar-C), 60.1 (-CH2),
52.2, 50.0 (-CH2-), 44.7 (-CH2-), 13.0 (-CH3); MS (m/e):
462.15 [M+].
6-(4-Benzylpiperazin-1-yl)-N4, N4-bis-(4-nitrophenyl)-
1,3,5-triazine-2,4-diamine (5f):Yellow; IR (KBr, νmax, cm-1):
3374 (N-Hstretch, >NH), 3082 (C-Hstretch, Ar); 2964 (C-Hstretch),
2367 (C-Nstretch), 1601, 1500, 1450 (C-Cstretch, Ar), 1550, 1431
(N-Ostretch, -NO2), 1324 (C-Hbend), 1318, 1250 (C-Nstretch, Ar);
4-(4-Benzylpiperazin-1-yl)-6-(1H-imidazol-1-yl)-N,N-
diisopropyl-1,3,5-triazine-2-amine(5b): Brownish gray; IR
(KBr, νmax, cm-1): 3099 (C-Hstretch, Ar), 2917 (C-Hstretch), 2345,
2367 (C-Nstretch, s-triazine), 1551, 1453 (C-Cstretch, Ar), 1304,
1
1214 (C-Nstretch), 848 (C-Hbend, Ar); H NMR (300 MHz,
DMSO-d6): δ 8.138, 8.055, 8.027 (t, 5H, J = 7.23, Ar-H), 8.215
(s, 2H, J = 7.23,Ar-H), 7.411 (s, 2H, J = 1.50,Ar-H), 4.223 (s,
1H, J = 2.15, NH), 3.326 (s, 2H, J = 28.04), 2.677, 2.639 (d,
4H, J = 1.36, -CH2-); 13C NMR (100 MHz, DMSO-d6): δ 182.4,
161.0 (C of s-triazine), 149.2, 138.4, 135.6 (C-Ar), 128.9,
128.5, 127.3, 121.9, 117.2 (-CH-), 60. 1(-CH2-) 52.2, 50.0
(-CH2-); MS (m/e): 527.21 [M+].
1229 (C-Nstretch), 1105 (C-Nstretch), 1383 (C-Hbend), 809 (C-Hbend
,
Ar); 1H NMR (300 MHz, DMSO-d6): δ 7.825, 7.747, 7.561 (t,
3H, J = 0.55, Ar-H), 7.335, 7.317, 7.256 (t, 5H, J = 0.55,
Ar-H), 3.799 (s, 2H, J = 14.83, -CH2-), 3.548, 3.446 (d, 4H,
J = 15.92, -CH2-), 2.447 (s, 2H, J = 1.0, >CH-), 1.315, 1.293,
1.165, 1.154 (m, 12H, J = 32.54, -CH3); 13C NMR (100 MHz,
DMSO-d6): δ 181.0, 172.9 (C of s-triazine), 135.6 (C-Ar),
134.5,128.9, 128.5, 127.8, 127.3, 114.7 (-CH- of Ar), 60.1
(-CH2-), 52.2, 50.0 (-CH2-), 46.9 (-CH-), 21.5 (-CH3); MS
(m/e): 420.56 [M+].
2-(4-Benzylpiperazin-1-yl)-4,6-dimorpholino-1,3,5-
triazine(5g):White ; IR (KBr, νmax, cm-1): 3098 (C-Hstretch,Ar),
2989 (C-Hstretch), 2367, 2352 (C-Nstretch), 1557, 1454 (C-Cstretch
,
Ar), 1305, 1256 (C-Nstretch) 1105 (C-Nstretch), 1362 (C-Hbend),
874 (C-Hbend,Ar); 1H NMR (300 MHz, CDCl3): δ 7.330, 7.316,
7.256 (t, 5H, Ar-H), 3.781, 3.728, 3.710, 3.704, 3.531 (m,
10H, J = 46.03, -CH2-); 13C NMR (100 MHz, CDCl3): δ 182.4,
177.6 (C of s-triazine); δ 135.6 (C-Ar), 128.9, 128.5, 127.3
(-CH-), 60.1 (-CH2-) 52.2, 50.0 (-CH2-), 66.4, 46.3 (-CH2-);
MS (m/e): 425.24 [M+].
6-(4-Benzylpiperazin-1-yl)-N2,N2-diisopropyl-N4-
(naphthalen-1-yl)-1,3,5-triazine-2,4-diamine(5c): Gray; IR
(KBr, νmax, cm-1): 3353 (N-Hstretch, >NH), 3081 (C-Hstretch, Ar),
2917 (C-Hstretch), 2367, 2324 (C-Nstretch), 1565, 1500, 1452
(C-Cstretch, Ar), 1312, 1287 (C-Nstretch), 1012 (C-Nstretch), 1387
(C-Hbend); 887.40 (C-Hbend, Ar); 1H NMR (300 MHz, CDCl3):
δ 7.469, 7.336, 7.247 (m, 5H, J = 3.64, Ar-H), 8.062, 8.039,
7.842, 7.621, 7.595, 6.940 (m, 7H, Ar-H), 4.357 (s, 1H, J =
1.50, NH), 3.822, 3.696 (d, 4H, J = 5.79, -CH2-), 3.535 (s, 2H,
J = 0.03,-CH2-), 2.883 (s, 1H, J = 0.34, >CH-), 1.255 (s, 12H,
J = 11.57, -CH3); 13C NMR (100 MHz, CDCl3): δ 182.4, 179.2,
159.4 (C of s-triazine), 142.0, 135.6, 134.3, 124.7 (C-Ar),
128.9, 128.6, 128.5, 127.3, 126.6, 126.0, 125.0, 121.0,119.0,
109.4 (-CH-Ar), 60.1 (-CH2-), 52.2, 50.0 (-CH2-), 46.9 (>CH-
), 21.5 (-CH3); MS (m/e): 495.38 [M+].
4-(4-Benzylpiperazin-1-yl)-6-(1H-imidazol-1-yl)-N-[4-
(4-nitro phenyl) thiazol-2-yl]-1,3,5-triazine-2-amine (5h):
Brown; IR (KBr, νamx, cm-1): 3399 (N-Hstretch, >NH); 3096
(C-Hstretch,Ar); 2917 (C-Hstretch), 2345 (C-Nstretch), 1654 (N-Hbend),
1601, 1500, 1450 (C-Cstretch, Ar), 1557, 1421 (N-Ostretch, -NO2),
1323 (C-Hbend), 1189, 1207 (C-Nstretch), 1214.78 (C-Nstretch), 842
(C-Hbend, Ar); 1H NMR (300 MHz, DMSO-d6): δ 8.416, 7.411
(d, 4H, J = 7.32, Ar-H), 8.243, 8.215, 8.138 (t, 5H, J = 7.32,
Ar-H), 8.388, 8.055, 8.027 (t, 3H, J = 7.32, Ar-H), 7.223 (s,
1H, J = 2.15, thiazolyl), 4.026 (s, 1H, J = 1.86, NH), 2.677,
2-(4-Benzylpiperazin-1-yl)-4-morpholino-6-(4-
nitrophenoxy)-1,3,5-triazine(5d):Yellowish white, IR (KBr,
2.639 (d, 4H, J = 1.36), 2.501 (s, 2H, J = 31.26, -CH2-); 13
C
ν
max, cm-1): 3088 (C-Hstretch, Ar), 2936 (C-Hstretch), 2367, 2361
NMR (100 MHz, DMSO-d6): δ 181.0, 176.1, 161.2 (C of
s-triazine), 160.5, 148.4 (thiazolyl-C) 148.2, 139.2, 135.6
(C-Ar), 134.5, 128.9, 128.5, 128.4, 127.3, 127.8, 121.6, 114.7
(-CH-), 100.0 (-CH-), 60.1 (C of -CH2-), 52.2, 50.0 (-CH2-);
MS (m/e): 540.21 [M+].
6-(4-Benzylpiperazin-1-yl)-N2,N2-diethyl-N4,N4-
diisopropyl-1,3,5-triazine-2,4-diamine(5i):Yellowish white,
IR (KBr, νmax, cm-1): 3089 (C-Hstretch,Ar), 2929 (C-Hstretch), 2351,
2347 (C-Nstretch), 1550, 1451 (C-Cstretch, Ar), 1354, 1229
(C-Nstretch, s-triazine), 1547, 1453 (C-Cstretch, Ar), 1304, 1229
(C-Nstretch), 1123 (C-Nstretch), 1383 (C-Hbend), 807 (C-Hbend, Ar);
1H NMR (300 MHz, DMSO-d6): δ 7.788 (s, 2H, J = 1.00,
Ar-H), 6.790 (s, 2H, J = 1.26, Ar-H ) 7.323, 7.283, 7.070 (t,
5H, J = 10.69, Ar-H), 3652 (s, 2H, J = 12.06, -CH2-), 3.171,
3.106 (d, 4H, J = 12.06), 3.654 (s, 2H, J = 1.51), δ 2.594 (s,
2H, J = 3.04); 13C NMR (100 MHz, DMSO-d6): δ δ183.7,
178.6, 177.9 (C of s-triazine), 161.3, 144.3, 135.6 (C-Ar),

Vol. 25, No. 1 (2013)
Synthesis and Antibacterial Activity of Some Novel 4-Benzyl-piperazinyl-s-triazine Derivatives 189
(C-Nstretch), 1142 (C-Nstretch), 1379 (C-Hbend), 804 (C-Hbend, Ar);
1H NMR (300 MHz, CDCl3): δ 7.335, 7.317, 7.256 (t, 5H, J =
0.55, Ar-H), 3.799 (s, 2H, J = 14.83, -CH2-), 3.548, 3.248 (d,
4H, J = 2.52, -CH2-), 3.018 (s, 2H, J = 4.72, >CH-), 1.165,
1.154 (d, 18H, J = 32.54, -CH3); 13C NMR (100 MHz, CDCl3):
δ 182.4, 179.2, 176.0 (C of s-triazine); δ135.6 (C-Ar), 128.9,
128.5, 127.3 (-CH-), 60.1 (-CH2-), 52.2, 50.0 (-CH2-), 46.9
(>CH-), 44.7 (-CH2-), 21.5 (-CH3), 13.0 (-CH3); MS (m/e):
425.37 [M+].
zones of inhibition of all the synthesized compounds (Table-2)
were determined preliminary for antibacterial screening by
disk-diffusion method (Kirby-Bauer method) recommended
by clinical and laboratory standards38.
RESULTS AND DISCUSSION
We observed that all the ten compounds for antibacterial
activity. Beside these six compounds (5a, 5c, 5e, 5g, 5i and
5j) showed satisfied antibacterial activity and other four comp-
ounds (5b, 5d, 5f and 5h) did not display little antibacterial
activity.
2, 4-Bis-(4-benzylpiperazin-1-yl)-6-(1H-imidazol-1-yl)-
1,3,5-triazine (5j): Brownish yellow, IR (KBr, νmax, cm-1): 3084
(C-Hstretch, Ar), 2983 (C-Hstretch), 2365, 2358 (C-Nstretch), 1607,
1557, 1518 (C-Cstretch, Ar), 1304, 1229 (C-Nstretch), 105.73
The zone of inhibition of synthesized compounds (six
compounds) against representative micro-organisms showed
a significant activity with degree of variation and these are
given in Table-2.
1
(C-Nstretch), 1383 (C-Hbend), 806 (C-Hbend, Ar); H NMR (300
MHz, DMSO-d6): δ 7323, 7.283, 7.070 (t, 10H, J = 10.69,
Ar-H); δ 6.790, 6.531, 6.145 (t, 3H, J = 9.08, Ar-H), 3.652 (s,
2H, J = 6.0, -CH2-), 3.652, 3.57, 3.356, 3.356 (t, 6H, J = 26.0,
-CH2-); 13C NMR (100 MHz, DMSO-d6): δ 181.0, 172.9 (C of
s-triazine), 135.6 (C-Ar), 134.5, 128.9, 128.5, 127.8, 127.3,
114.7 (-CH-), 60.1 (-CH2-), 52.2, 50.0 (-CH2-); MS (m/e):
495.29 [M+].
The MIC values of substituted 4-benzyl piperazinyl-s-
triazine derivatives found to be in the range between 2-32 µg
mL-1 and these are given in Table-3.
It was found that the 4-benzyl piperazinyl-s-triazine
derivatives showed significant antibacterial activity in compa-
rison to streptomycin. The 5a and 5c against S. aureus; 5a
against B. subtilis and 5c against S. epidermis showed same
MIC value as standard streptomycin. Most of the synthesized
compounds showed antibacterial activity against P. aeruginosa,
except 5j showed activity only against P. mirabilis. The
compound 5i showed broad spectrum activity; 5a and 5c have
better activity against Gram-positive organisms than Gram-
negative; 5e and 5j have activity against only Gram-negative
organisms. Among the organisms B. subtilis, B. cerus, S.
aureus, S. epidermis, P. aeruginosa, P. mirabilis are more
susceptible and E. coli and K. pneumonia are less susceptible
to synthesized compounds. Among all the synthesized
Antibacterial activity: The in vitro antibacterial scree-
ning of all the compounds was evaluated against selected
(Table-1) four Gram-positive organisms viz. Bacillus subtilis
(NCIM 2063), Bacillus cerus (NCIM 2156), Staphylococcus
aureus (NCIM 2079), Staphylococcus epidermis (NCIM 2493)
and four representative Gram-negative organisms viz. Escheri-
chia coli (NCIM 2065), Klebseilla pneumonia (NCIM 2706),
Proteus mirabilis (NCIM 2241), Pseudomonas aeruginosa
(NCIM 2036) along with streptomycin as standard by broth
dilution method recommended by European committee for
antibacterial susceptibility testing (EUCAST) standards37. The
TABLE-2
ZONE OF INHIBITION OF SYNTHESIZED COMPOUNDS
Zone of inhibition (mm)a,b
Gram-positive organisms
B. cerus S. aureus
7.0 0.816 11.67 0.471 6.67 0.471
Gram-negative organisms
K. pneumonia P. aeruginosa P. mirabilis
Compound
B. subtilis
S. epidermis
E. coli
5a
5c
5e
5g
5i
9.67 0.471
-
-
4.67 0.471
4.0 0.816
4.67 0.471
10.67 0.471
8.67 0.471
-
-c
6.67 0.471
-
9.0 0.816
9.67 0.471
-
-
-
-
-
-
-
-
-
3.0 0.471
-
-
-
7.67 0.471
3.67 0.816
-
-
5.67 0.471
-
9.0 0.816 10.67 0.471 5.67 0.471
-
-
6.0 0.816
-
7.67 0.471
7.0 0.816
5j
-
-
-
Streptomycin 9.67 0.471 11.0 0.816 10.67 0.471 9.67 0.471 10.0 0.816
aDMSO as negative control; bData are mean of three replications; cNo inhibition was observed
9.67 0.471 11.67 0.471 10.67 0.471
TABLE-3
MINIMUM INHIBITORY CONCENTRATION (MIC) OF SYNTHESIZED COMPOUNDS
MIC (µg mL-1)a
Gram-positive organisms
Gram-negative organisms
Compound
B. subtilis
B. cerus
S. aureus
S. epidermis
E. coli
K. pneumonia P. aeruginosa P. mirabilis
b
8
16
-
5a
8
-
2
2
-
16
4
-
-
-
-
16
16
16
4
-
5c
-
5e
-
-
32
32
-
-
-
-
5g
8
8
-
-
-
-
-
16
-
5i
5j
2
-
16
-
16
-
8
4
4
2
-
-
8
Streptomycin
4
2
4
4
4
4
aDMSO as negative control; bNo antibacterial activity

190 Jana et al.
Asian J. Chem.
compounds 5a, 5c and 5i have better antibacterial activity than
others.A comparative MIC bar plot of synthesized compounds
with reference streptomycin is given in Fig. 1.
ACKNOWLEDGEMENTS
The authors thank to All India Council of Technical
Education (AICTE), New Delhi for award of fellowship.
REFERENCES
35
B. subtilis
1. D.T.W. Chu, J.J. Plattner and L. Katz, J. Med. Chem., 39, 3853 (1996).
2. K.M. Overbye and J.F. Barrett, Drug Discov.Today, 10, 45 (2005).
3. C. Walsh, Nature, 406, 775 (2000).
B. cerus
30
S. aureus
25
4. L.B. Rice, Biochem.Pharm., 71, 991(2006).
5. D.M. Shlaes, S.J. Projan and J.E. Edwards, ASM News, 70, 275 (2004).
6. T. Travis, Science, 264, 360 (1994).
S. epidermis
E. coli
20
K. pneumonia
7.
L. Otvos Jr., J.D.Wade, F. Lin, B.A. Condie, J. Hanrieder and R. Hoffmann,
J. Med. Chem., 48, 5349 (2005).
15
10
5
P. aeruginosa
P. mirabilis
8. R.L. Jarvest, J.M. Berge, V. Berry, H.F. Boyd, M.J. Brown, J.S. Elder,
A.K. Forrest, A.P. Fosberry, D.R. Gentry, M.J. Hibbs, D.D. Jaworski,
P.J. O'Hanlon, A.J. Pope, S. Rittenhouse, R.J. Sheppard, C.S. Radosti
and A. Worby, J. Med. Chem., 45, 1959 (2002).
9. C.G. Boojamra, R.C. Lemoine, J.C. Lee, R. Leger, K.A. Stein, N.G.
Vernier,A. Magon, O. Lomovskaya, P.K. Martin, S. Chamberland, M.D.
Lee, S.J. Hecker and V.J. Lee, J. Am. Chem. Soc., 123, 870 (2001).
10. H. Xin and K.A. Reynolds, Antimicrob. Agents Chemother., 46, 1310 (2002).
11. R.A. Daines, I. Pendrak, K. Sham, G.S.V. Aller, A.K. Konstantinidis,
J.T. Lonsdale, C.A. Janson, X. Qiu, M. Brandt, S.S. Khandekar, C.
Silverman and M.S. Head, J. Med. Chem., 46, 5 (2003).
0
5a
5c
5e
5g
5i
5j Streptomycin
Fig. 1. A comparative MIC bar plot of synthesized compounds with
streptomycin
12. Y. Cui, Y. Dang, Y. Yang, S. Zhang and R. Ji, Eur. J. Med. Chem., 40,
209 (2005).
13. A. Baliani, G.J. Bueno, M.L. Stewart, V. Yardley, R. Brun, M.P. Barrett
and I.H. Gilbert, J. Med. Chem., 48, 5570 (2005).
14. R. Menicagli, S. Samaritani, G. Signore, F. Vaglini, L.D. Via, J. Med.
Chem., 47, 4649 (2004).
15. D.P. Grishold Jr, B.J. Roberts, D.J. Dykes, W.R. Leopold, T.H. Corbett
and F.M. Schabel Jr., Can. Res., 42, 1707 (1982).
16. A. Dandia and K. Arya, Bioorg. Med. Chem. Lett., 17, 3298 (2007).
17. B.R. Henke, T.G. Consler, N. Go, R.L. Hale, D.R. Hohman, S.A. Jones,
A.T. Lu, L.B. Moore, J.T. Moore, L.A. Orband-Miller, R.G. Robinett,
J. Shearin, P.K. Spearing, E.L. Stewart, P.S. Turnbull, S.L. Weaver, S.P.
Williams, G.B. Wisely and M.H. Lambert, J. Med. Chem., 45, 5492 (2002).
18. N.P. Jensen, A.L. Ager, R.A. Bliss, C.J. Canfield, B.M. Kotecka, K.H.
Rieckmann, J. Terpinski and D.P. Jacobus, J. Med. Chem., 44, 3925 (2001).
19. A.Agarwal, K. Srivastava, S.K. Puri and P.M.S. Chauhan, Bioorg. Med.
Chem. Lett., 15, 1881 (2005).
20. A. Agarwal, K. Srivastava, S.K. Puri and P.M.S. ChauhanA. Agarwal,
K. Srivastava, S.K. Puri and P.M.S. Chauhan, Bioorg. Med. Chem. Lett.,
15, 3130 (2005).
21. H.G. Ian, R. Brun, P.B. Michael and B. Klenke, J. Antimicrob.
Chemother., 52, 290 (2003).
Antibacterial susceptibility testing results reflects that
aliphatic amino (diethyl amino, isopropyl amino) substituted
4-benzyl-piperazinyl-1,3,5-triazine (5a, 5c and 5i) show better
and broad spectrum activity; aromatic amino (naphthalen-1-
yl group in 5c) and aromatic amino with electronegative group
(4-nitrophenyl amino in group 5a) also shows better activity.
But bis-(4-nitro-phenyl amino) substituted 1,3,5-triazine (5f)
have no activity, hence attachment of more electronegative
group decreases or destroy the activity.
The interesting point is that the amino substituted s-triazine
show antibacterial activity but other substitution like phenoxy
substitution (5d and 5e) shows no or little activity. Other hete-
rocyclic substitution like imidazolyl (5b, 5h and 5j) and
morpholino group (5d, 5g) are not improved or slightly
improved the activity. Although 4-(4-nitrophenyl)-thiazol-2-
amino substituted-1,3,5-triazine32 and 4-benzyl piperazinyl
substituted-1,3,5-triazine show better antibacterial activity but
4-(4-nitrophenyl)-thiazol-2-amino with 4-benzyl piperazinyl
substituted-1,3,5-triazine (5h) derivatives have no antibacterial
activity and bis-(4-benzylpiperazinyl) substituted 1,3,5-triazine
(5j) have little antibacterial activity.
22. G.H. Kuo,A. DeAngelis, S. Emanuel, A. Wang,Y. Zhang, P.J. Connolly,
X. Chen, R.H. Gruninger, C. Rugg, A.F. Pesquera, S.A. Middleton, L.
Jolliffe and W.V. Murray, J. Med. Chem., 48, 4535 (2005).
23. V.K. Pandey, S. Tusi, Z. Tusi, M. Joshi and S. Bajpai, Acta Pharm., 54,
1 (2004).
24. S. Knapp, J.J. Hale, M. Bastos and F.S. Gibson, Tetrahedron Lett., 31,
2109 (1990).
25. K. Alfred and S. Irmtraut, Arch. Pharm., 321 (1988).
26. J. Modha, N. Datta and H. Parekh, IL Farmaco., 56, 641 (2001).
27. O. Lafont, P.Verite, S. Menager andA. Ghaib, IL Farmaco., 57, 109 (2002).
28. K. Srinivas, U. Srinivas, K. Harakishore, V.J. Rao, K. Bhanuprakash
and U.S.N. Murthy, Bioorg. Med. Chem. Lett., 15, 1121 (2005).
29. A. Solankee, K. Kapadia, S. Lad, J. Patel and I. Thakor, Asian J. Chem.,
16, 727 (2004).
30. A. Ghaib, S. Menager, P.Verite and O. Lafont, IL Farmaco, 57, 109 (2002).
31. T. Lubbers, P.Angehrn, H. Gmunder, S. Herzig and J. Kulhanek, Bioorg.
Med. Chem. Lett., 10, 821 (2000).
32. P. Gahtori, A. Das and H. Bhatt, Indian J. Pharm. Sci., 71, 79 (2009).
33. P. Chaudhary, R. Kumar,A.K. Verma, D. Singh, V.Yadav,A.K. Chhillar,
G.L. Sharma and R. Chandra, Bioorg. Med. Chem., 14, 1819 (2006).
34. V. Patel and V. Desai, Asian J. Chem., 15, 1131 (2003).
35. G. Blotny, Tetrahedron, 62, 9507 (2006).
36. J.T. Thurston, J.R. Dudley, D.W. Kaiser, I. Hechen-.Isleikner, F.C.
Schaeffer and D. Holm-Hansen, J. Am. Chem. Soc., 73, 2981 (1951).
37. European Committee for Antimicrobial Susceptibility Testing, Defini-
tive Document E. Def 3.1., Clin. Microbiol. Infect., 6, 509 (2000).
38. Performance Standards for Antimicrobial Disk Susceptibility Tests,
Approved Standard-Ninth Edition. Clinical and Laboratory Standards,
Institute document M2-A9 [ISBN 1-56238-586-0], Clinical and Labo-
ratory Standards Institute, Wayne, Pennsylvania 19087-1898 USA (2006).
Conclusion
We have presented a new economical synthesis of a series
of 4-benzyl-piperazinyl-s-triazine. The operational simplicity,
good yield in significantly very short reaction times, can
impose this procedure as a useful and attractive alternative to
the currently available antibacterial. With an objective to
investigate a compound for bacterial resistance we have found
that most of compounds exhibited moderate to significant in
vitro antibacterial activity. Aliphatic amino (diethyl amino,
isopropyl amino) substituted 4-benzyl-piperazinyl-1,3,5-
triazine (5a, 5c and 5i) show better and broad spectrum activity,
aromatic amino (naphthalenyl group in 5c) and aromatic amino
with electronegative group (4-nitrophenyl amino in group 5a)
also shows better activity. Hence, it is concluded that the nitro
substituted phenyl amine, aliphatic amine substituted 4-benzyl-
piperazinyl-s-triazine derivatives are potential key approach
to design newer antibacterial agents.