A. Rajasekaran, P.P. Thampi / European Journal of Medicinal Chemistry 39 (2004) 273–279
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171–172 °C. IR: 2864 (C–H), 1692 (C=O), 1596 and 1570
(phenothiazine ring), 1458 (C–H), 1348 and 1127 (N=O),
1283 (N–N=N–), 1108 and 1138 (tetrazole ring) cm–1. 1H-
NMR (DMSO-d6) d 2.8 (2H, t, J = 7.1 Hz, CH2), 4.3 (2H, t,
J = 7.1 Hz, CH2), 6.9–8.3 (12H, m, Ar–H). Anal. Calcd. for
C22H16N6O3S: C, 59.45; H, 3.63; N, 18.91. Found: C, 59.25;
H, 3.61; N, 18.82.
5.1.13. 5-[b-(Phenothiazinyl-10-yl))ethyl-1-(phenyl acetyl)-
1,2,3,4-tetrazole (13)
Compound 13 was prepared using the same procedure as
for 4, and was obtained in 64% yield as a light brown solid:
m.p. 127–128 °C. IR: 2928 (C–H), 2853 (C–H), 1687 (C=O),
1596 and 1570 (phenothiazine ring), 1583 (C=C), 1457
(C–H), 1283 (N–N=N–), 1108 and 1138 (tetrazole ring)
cm–1. 1H-NMR (CDCl3) d 2.3 (2H, s, CH2), 2.8 (2H, t,
J = 7.1 Hz, CH2), 4.3 (2H, t, J = 7.1 Hz, CH2), 6.8–7.3 (13H,
m, Ar–H). Anal. Calcd. for C23H19N5OS: C, 66.81; H, 4.63;
N, 16.94. Found: C, 66.72; H, 4.61; N, 16.86.
5.1.9. 5-[b-(Phenothiazinyl-10-yl))ethyl-1-(p-hydroxyben-
zoyl)-1,2,3,4-tetrazole (9)
Compound 9 was prepared using the same procedure as
for 4, and was obtained in 62% yield as a light brown solid:
m.p. >210 °C. IR: 3390 (O–H), 1744 (C=O), 1596 and 1570
(phenothiazine ring), 1458 (C–H), 1283 (N–N=N–),
1108 and 1138 (tetrazole ring), 885 (O–H) cm–1. 1H-NMR
(CDCl3) d 2.8 (2H, t, J = 7.1 Hz, CH2), 4.3 (2H, t, J = 7.1 Hz,
CH2), 5 (1H, s, OH), 6.85–7.37 (12H, m,Ar–H).Anal. Calcd.
for C22H17N5O2S: C, 63.60; H, 4.12; N, 16.86. Found: C,
63.54; H, 4.11; N, 16.83.
5.1.14. 5-[b-(Phenothiazinyl-10-yl))ethyl-1-(p-toluenesul-
phonyl)-1,2,3,4-tetrazole (14)
Compound 14 was prepared using the same procedure as
for 4, and was obtained in 60% yield as a grayish black solid:
m.p. 97–98 °C. IR: 2954 (C–H), 1596 and 1570 (phenothiaz-
ine ring), 1457 (C–H), 1283 (N–N=N–), 1380 and 1173
(S=O), 1108 and 1138 (tetrazole ring) cm–1. 1H-NMR
(DMSO-d6) d 2.5 (3H, s, CH3), 2.8 (2H, t, J = 7.1 Hz, CH2),
4.3 (2H, t, J = 7.1 Hz, CH2), 6.8–7.9 (12H, m, Ar–H). Anal.
Calcd. for C22H19N5O2S2: C, 58.78; H, 4.26; N, 16.94.
Found: C, 58.57; H, 4.23; N, 16.88.
5.1.10. 5-[b-(Phenothiazinyl-10-yl))ethyl-1-(p-aminoben-
zoyl)-1,2,3,4-tetrazole (10)
Compound 10 was prepared using the same procedure as
for 4, and was obtained in 62% yield as a dark brown solid:
m.p. >210 °C. IR: 3346 (N–H), 2880 (C–H), 1703 (C=O),
1596 and 1570 (phenothiazine ring), 1458 (C–H), 1320
(C–N), 1285 (N–N=N) 1108 and 1138 (tetrazole ring) cm–1.
5.2. Evaluation of analgesic activity
Swiss strain albino mice of either sex weighing 25–30 g
were used for this study. The test compounds were adminis-
tered intraperitoneally in 1/10th of the dose of 250 mg/kg
(LD50) in 10% v/v Tween 80 suspensions. LD50 of the newly
synthesized compounds were determined by Miller and
Tainter method [35] administering the compounds intraperi-
toneally.
1
H-NMR (DMSO-d6) d 2.8 (2H, t, J = 7.1 Hz, CH2), 3.63
(2H, s, NH2), 4.3 (2H, t, J = 7.1 Hz, CH2), 6.6–7.8 (12H, m,
Ar–H). Anal. Calcd. for C22H18N6OS: C, 63.75; H, 4.38; N,
20.28. Found: C, 63.68; H, 4.13; N, 20.18.
5.1.11. 5-[b-(Phenothiazinyl-10-yl))ethyl-1-(p-methylben-
zoyl)-1,2,3,4-tetrazole (11)
5.2.1. Acetic acid induced writhing method [27]
Compound 11 was prepared using the same procedure as
for 4, and was obtained in 64% yield as a light grey solid:
m.p. 121–122 °C. IR: 2972 (C–H), 1675 (C=O), 1611(C=C),
1596 and 1570 (phenothiazine ring), 1457 (C–H), 1283 (N–
N=N–), 1108 and 1138 (tetrazole ring) cm–1. 1H-NMR
(DMSO-d6) d 2.5 (3H, s, CH3), 2.8 (2H, t, J = 7.1 Hz, CH2),
4.3 (2H, t, J = 7.1 Hz, CH2), 6.8–7.9 (12H, m, Ar–H). Anal.
Calcd. for C23H19N5OS: C, 66.81; H, 4.63; N, 16.94. Found:
C, 66.58; H, 4.61; N, 16.89.
The animals were divided into 15 groups of 10 mice each.
The control group of animals was administered with 10% v/v
Tween 80 (0.5 ml) suspension. The standard drug was admin-
istered with Nimesulide (Dr. Reddy’s Laboratories), intrap-
eritoneally in a dose of 10 mg/kg. After 20 min of the
administration the test compounds, all the groups of mice
were given with the writhing agent 3% v/v aqueous acetic
acid in a dose of 2 ml/kg intraperitoneally. The writhings
produced in these animals were counted visually for 15 min
and the numbers of writhings produced in treated groups
were compared with those in the control group. The results
are analyzed statistically by student “t” test and recorded in
5.1.12. 5-[b-(Phenothiazinyl-10-yl))ethyl-1-(p-methoxyben-
zoyl)-1,2,3,4-tetrazole (12)
Compound 12 was prepared using the same procedure as
for 4, and was obtained in 68% yield as a light brown solid:
m.p.158–159 °C. IR: 2985 (C–H), 1686 (C=O), 1604 (C=C),
1596 and 1570 (phenothiazine ring), 1457 (C–H), 1283 (N–
N=N–), 1108 and 1138 (tetrazole ring) cm–1. 1H-NMR
(CDCl3) d 2.8 (2H, t, J = 7.1 Hz, CH2), 3.9 (3H, s,CH3 ), 4.3
(2H, t, J = 7.1 Hz, CH2), 6.4–8.1 (12H, m, Ar–H). Anal.
Calcd. for C23H19N5O2S: C, 64.32; H, 4.46; N, 16.31. Found:
C, 64.15; H, 4.04; N, 16.27.
5.2.2. Hot plate method [28]
The method suggested by Eddy and Leimbach [28] was
adopted for the study. The pain threshold of the animals was
measured on a hot plate before treatment of the test and
reference compounds, and the animals that showed more
than 10 s of reaction time were rejected. The reference
compound morphine sulphate (Dr. Reddy’s Laboratories)