Synthesis of novel triheterocyclic thiazoles as anti-inflammatory and analgesic agents

Article abstract of DOI:10.1016/j.ejmech.2007.01.023

Triheterocyclic thiazoles containing coumarin and carbostyril (1-aza coumarin) have been synthesized by the reaction of the in situ generated 4-thioureidomethyl carbostyril and 3-bromoacetyl coumarins. The new compounds have been tested for their in vivo analgesic and anti-inflammatory activities. Qualitative SAR studies indicate that, the chloro substitution at C-7 in carbostyril and 6,8-dibromo substitution in the coumarin ring enhance anti-inflammatory activity. These compounds were also found to provide significant protection against acetic acid writhing in animal models. All the compounds have been characterized by IR, ¹H NMR, ¹³C NMR and mass spectrometry.

Full text of DOI:10.1016/j.ejmech.2007.01.023

European Journal of Medicinal Chemistry 42 (2007) 1272e1276
http://www.elsevier.com/locate/ejmech
Original article
Synthesis of novel triheterocyclic thiazoles as
anti-inflammatory and analgesic agents
a
R.G. Kalkhambkar , G.M. Kulkarni , H. Shivkumar , R. Nagendra Rao
a,*
b
b
a
Department of Chemistry, Karnatak Science College, College Road, Dharwad-580001, Karnataka, India
b
S.C.S. College of Pharmacy, Harapanahalli-583131, Karnataka, India
Received 11 November 2006; received in revised form 12 January 2007; accepted 12 January 2007
Available online 27 January 2007
Abstract
Triheterocyclic thiazoles containing coumarin and carbostyril (1-aza coumarin) have been synthesized by the reaction of the in situ generated
-thioureidomethyl carbostyril and 3-bromoacetyl coumarins. The new compounds have been tested for their in vivo analgesic and anti-inflam-
4
matory activities. Qualitative SAR studies indicate that, the chloro substitution at C-7 in carbostyril and 6,8-dibromo substitution in the coumarin
ring enhance anti-inflammatory activity. These compounds were also found to provide significant protection against acetic acid writhing in an-
1
imal models. All the compounds have been characterized by IR, H NMR, C NMR and mass spectrometry.
13
Ó 2007 Elsevier Masson SAS. All rights reserved.
Keywords: Triheterocyclic thiazoles; In vivo analgesic; Anti-inflammatory activities; Ulcerogenic
1
. Introduction
carbostyrils [9] it was thought of interest to synthesize some
triheterocycles containing coumarin and 1-aza coumarins (car-
bostyrils) linked to thiazole moiety.
Coumarins and carbostyrils (1-aza coumarin) with diverse
structural features and versatile biological properties such as
anti-microbial, anti-cancer, anti-inflammatory and anti-HIV
activities have been recently reviewed [1]. Linkage of various
heterocycles at C-4 position in 2-arylamino thiazoles has re-
sulted in novel molecular matrices which were associated
with anti-neoplastic activity [2]. Number of 2,4-disubstituted
thiazoles [3], imidazolyl thiazoles [4], and pyrazolyl thiazoles
2. Chemistry
The sequence of the reactions employed for the construction
of triheterocyclic molecular library is outlined in Scheme 1.
4-Bromomethyl carbostyrils (1e3) were synthesized by bro-
mination of acetoacetanilides and cyclising the intermediate
u-bromo acetoacetanilides in sulphuric acid [10]. They were
converted to 4-aminomethyl carbostyril hydrochlorides (4e6)
by the acid hydrolysis of their hexamine adducts, which were
prepared by the reaction of compounds (1e3) with hexamethy-
lenetetramine. Corresponding thioureas (7e9) were easily
generated in situ by the reaction of compounds (4e6) with
potassium thiocyanate in dry methanol. 3-Acetyl coumarins
[
5] have been recognized as potent anti-inflammatory and an-
algesic agents. Synthesis of many 3-substituted biheterocyclic
coumarins with thiazoles and fused thiazoles possessing anti-
microbial and anti-inflammatory agents has been reported
from our laboratory [6e8]. In view of our earlier observation
on the anti-inflammatory activity associated with 4-substituted
(
13e15) were synthesized by the reaction of salicylaldehydes
10e12) with ethylacetoacetate in the presence of catalytic
(
amount of piperidine at room temperature. These were
*
Corresponding author. Tel.: þ91 836 2770476; fax: þ91 836 2747884.
E-mail address: geeta_2562005@yahoo.com (G.M. Kulkarni).
0223-5234/$ - see front matter Ó 2007 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2007.01.023

R.G. Kalkhambkar et al. / European Journal of Medicinal Chemistry 42 (2007) 1272e1276
Br
1273
NH2 . HCl
i
R1
ii
N
H
O
R1
N
H
O
1
- 3
4 - 6
R2
iii
O
N
NH2
O
S
O
NH
Br
vi
S
NH
R2
R1
O
O
N
H
O
R1
16 - 18
N
O
H
7
- 9
v
19 - 27
O
O
O
CH3
iv
H
OH
R2
R2
O
13 - 15
10 - 12
R1
=
6-Cl, 7-Cl, 8-CH3
;
R2 = H, 6' - Br, 6' 8' - dibromo .
Scheme 1. Synthesis of tryheteroaryl thiazoles. Reagents and conditions: (i) Hexamine, ab. EtOH, reflux; (ii) conc. HCl, ab. EtOH, heat; (iii) KCNS, ab. MeOH,
reflux; (iv) E.A.A, piperidine, stirr at R.T.; (v) liq. Br , dry CHCl , stirr, reflux. (vi). ab. MeOH, reflux.
2
3
brominated according to the method of Koelsh [11] to obtain the
corresponding 3-bromoacetyl coumarins (16e18) [12]. Title
compounds (19e27) were obtained by the reaction of synthons
3.2. Analgesic activity
Abdominal constriction response induced by acetic acid is
sensitive procedure to establish efficacy of peripherally acting
analgesics. Intraperitonial administration of acetic acid causes
increase in the level of PGE2 and PGF 2a [14]. Amongst the
tested compounds, 22 and 26 significantly inhibited the acetic
acid induced writhing (up to 88% and 78%, respectively) and
other compounds (23e25) in the range of 64e35% as compare
to the standard. Thus compounds 22 and 26 appear to possess
significant peripheral anti-nociceptive activity. The analgesic
(
7e9) and coumarins (16e18) representing the double electro-
phile and double nucleophile approach for five membered het-
erocycles. Thiazole formation in refluxing methanol was
indicated by a stable canary yellow colour of the reaction mix-
ture and was found to be complete (TLC) in about 3e4 h. The
separated products were in a free base form and no hydrobro-
mides were isolated in accordance with earlier observations
[
13]. The reactions are outlined in Scheme 1 and the compounds
synthesized are given in Table 1. Structures of all the newly syn-
thesized compounds are well supported by spectral data such as
IR, NMR, mass and elemental analysis.
Table 1
List of triheteroaryl thiazoles synthesized (19e27)
Compound
R
1
R
2
1
2
2
2
2
2
9
0
1
2
3
4
6-Cl
7-Cl
8-CH
6-Cl
7-Cl
8-CH
6-Cl
7-Cl
8-CH
H
H
H
3
. Results and discussion
3
3
3
0
6 -Br
6 -Br
3
.1. Acute toxicity studies
0
0
6 -Br
6 ,8 -Br
0 0
It is found that, all the compounds have shown good safety
profile till the highest dose. No mortality of animals observed
even after 24 h.
25
0 0
6 ,8 -Br
2
2
6
7
0
0
6 ,8 -Br

1274
R.G. Kalkhambkar et al. / European Journal of Medicinal Chemistry 42 (2007) 1272e1276
activity was expressed as percentage of protection, the results
of which are summarized in Table 2.
60
50
3
.3. Anti-inflammatory activity
40
30
Inhibition of formalin induced paw oedema in rats is one of
the most acceptable test procedures to evaluate anti-inflamma-
tory agents [15,16]. Anti-inflammatory activity exhibited by
the compounds may be attributed to the inhibition of cycloxy-
genase enzyme, which plays a vital role in inflammation pro-
cess [17]. The standard used for the present anti-inflammatory
activity testing is phenyl butazone. The test compounds were
found to be slow acting anti-inflammatory agents. Hence the
results after 3 h for compounds (19e27) were not encourag-
ing. But the same compounds after 4 h till 8th hour showed
significant increase in the activity. Compound 26 has shown
inhibition, comparable with the standard at the 8th hour. The
same compound after 4th hour shows 69% inhibition. Almost
all compounds show increased activity at the 8th hour. This is
depicted in Fig. 1. Hence the compounds (22e27) seem to be
more effective as slow acting anti-inflammatory agents. The
results indicating the percentage inhibition of inflammation
at various time intervals have been summarized in Table 3.
20
10
0
0
5
10
15
Time in hours
20
25
+
30
22,
23,
24,
25,
26,
27 and
standard
Fig. 1.
4
(
.1.1. Preparation of triheterocycles (19e27)
general procedure)
A mixture of substituted 4-aminomethylcarbostyrilhydro-
chloride (4e6) (3.00 mmol) and potassium thiocyanate
6.00 mmol) in dry methanol (20 ml) was refluxed on a water
bath for 4 h. After cooling, the separated salt of potassium
sulfate was filtered, to the filtrate, 3-bromoacetylcoumarin
(16e18) (3.00 mmol) was added and the reaction mixture
was refluxed on a water bath for 4 h, and left overnight. A yel-
low colored solid obtained was filtered, washed with excess of
cold water, dried and crystallized from suitable solvent.
(
4
. Experimental
4
.1. Chemistry
The melting points were determined by open capillaries on
a Buchi apparatus and are uncorrected. The IR spectra were
recorded on a Nicolet-Impact-410 FT-IR spectrometer, using
4
.1.2. 4-{[4-(2-Oxo-2H-chromen-3-yl)-thiazol-2-ylamino]-
methyl}-6-chloro-1H-quinoline-2-one (19)
Yellow solid (methanol); yield: 74%; m.p. 152e154 C;
1
KBr pellets. H NMR and C NMR spectra were recorded
13
ꢁ
on a Bruker AC-300F, 300 MHz, spectrometer in CDCl using
3
ꢂ1
FAB-MS: 436 (M þ 1); IR (KBr): n
1657 cm (amide),
ꢂ1
C]O
TMS as an internal standard and the values are expressed in
d (ppm). The mass spectra were recorded using FAB-MS (In-
dian Institute of Technology, Bombay). The elemental analysis
was carried out using Heraus CHN rapid analyzer. All the new
compounds gave C, H and N analysis within ꢀ0.4% of the the-
oretical values. All the chemicals purchased were of analytical
reagent grade, and were used without further purification un-
less otherwise stated.
ꢂ1
ꢂ1
n
1720 cm (lactone), n
C]O
H NMR (300 MHz, CDCl , d ppm): 4.05 (s, 1H, C4-CH e
1611 cm , nNH3429 cm ;
C]N
1
3
2
NH ), 4.77 (s, 2H, C4-CH ), 7.32e8.18 (m, 10H, Ar-H),
2
13
.78 (s, 1H, NHCO); C NMR (75 MHz, CDCl , d ppm):
8
1
1
1
3
74.6, 161.4, 159.8, 155.9, 153.2, 150.8, 142.3, 139.6,
36.8, 132.1, 131.4, 128.6, 125.9, 124.8, 124.4, 122.6,
22.1, 120.8, 118.6, 110.9, 108.6, 58.98. Anal. calc. for
C H ClN O S (%): C, 60.62; H, 3.24; N, 9.64; found (%):
14
2
2
3 3
C, 60.32; H, 3.62; N, 9.80.
Table 2
Analgesic activities of the test compounds
4
.1.3. 4-{[4-(2-Oxo-2H-chromen-3-yl)-thiazol-2-ylamino]-
Compound
No. of. writhes
Percentage of
protection
methyl}-7-chloro-1H-quinoline-2-one (20)
Pale yellow solid (methanol); yield: 78%; m.p. 144e146 C;
ꢁ
2
2
2
2
2
2
2
3
4
5
6
7
05.01 ꢀ 0.73*
15.83 ꢀ 1.24*
06.16 ꢀ 0.60*
13.33 ꢀ 0.95*
09.83 ꢀ 0.79*
06.50 ꢀ 0.56*
45.16 ꢀ 0.90
08.33 ꢀ 0.42
88.89
64.94
35.05
48.70
78.22
62.73
ꢂ1
FAB-MS: 436 (M þ 1); IR (KBr): n
1659 cm (amide),
ꢂ1
C]O
ꢂ1
ꢂ1
n
1720 cm (lactone), n
C]O
H NMR (300 MHz, CDCl , d ppm): 4.13 (s, 1H, C4-CH e
1607 cm , nNH3438 cm ;
C]N
1
3
2
NH ), 4.70 (s, 2H, C4-CH ), 7.30e8.15 (m, 10H, Ar-H), 8.76
2
13
s, 1H, NHCO); C NMR (75 MHz, CDCl , d ppm): 174.8,
(
3
Control
Standard
1
1
1
62.6, 160.8, 156.6, 153.8, 151.1, 142.4, 138.8, 136.6, 132.4,
31.8, 129.6, 125.4, 125.1, 124.6, 122.8, 122.1, 120.6,
19.2, 110.0, 109.1, 60.3. Anal. calc. for C H ClN O S (%):
81.56
Values are expressed as mean ꢀ SEM. *P < 0.001 Vs control. Note: For both
2
2
14
3 3
the screened activities the results were analyzed by using one way ANOVA
F ¼ 76.782) followed by Turkey’s multiple comparative test. ‘P’ values of
C, 60.62; H, 3.24; N, 9.64; found (%): C, 60.28; H, 3.54;
N, 9.72.
(
P < 0.05, P < 0.01 and P < 0.001 were considered statistically significant.

R.G. Kalkhambkar et al. / European Journal of Medicinal Chemistry 42 (2007) 1272e1276
1275
Table 3
Anti-inflammatory activities of the test compounds
Compound % Inhibition of inflammation
0
h
0.5 h
1 h
4.42
2 h
5.26
4 h
8 h
12 h
24 h
2
2
2
2
2
2
2
3
4
5
6
7
3.03
2.40
1.60
2.85
2.89
2.65
5.97
4.11
5.26
3.12
6.75
3.27
3.65
9.76
19.83
13.27
14.52
29.83
34.53
22.73
49.89
28.57
24.48
18.52
21.85
41.47
33.73
39.71
15.55
23.17
24.08
14.36
18.73
16.73
22.17
9.08
18.40
16.85
9.35
5.80
8.76
9.09
9.19
13.75
12.56
11.27
17.08
17.75
13.04
16.34
29.89
10.58
9.78
17.45
Standard
ꢂ1
ꢂ1
ꢂ1
4
.1.4. 4-{[4-(2-Oxo-2H-chromen-3-yl)-thiazol-2-ylamino]-
n
1
C]O1730 cm (lactone), nC]N1610 cm , nNH3411 cm
;
methyl}-8-methyl-1H-quinoline-2-one (21)
H NMR (300 MHz, CDCl , d ppm): 2.45 (s, 3H, C8-CH ),
3 3
Brown solid (ethanol þ dioxan); yield: 70%; m.p. 158e
3.96 (s, 1H, C4-CH eNH ), 4.51 (s, 2H, C4-CH ), 7.32e
2 2
ꢁ
ꢂ1
13
8.10 (m, 9H, Ar-H), 8.80 (s, 1H, NHCO); C NMR
1
(
60 C; FAB-MS: 416 (M þ 1); IR (KBr): n
1668 cm
C]O
ꢂ1
ꢂ1
amide),
n
1719 cm
(lactone),
n
nNH3410 cm ; H NMR (300 MHz, CDCl , d ppm): 2.48
C]N1608 cm
,
(75 MHz, CDCl , d ppm): 174.6, 160.9, 159.8, 156.7, 153.8,
3
C]O
ꢂ1
1
151.1, 149.8, 141.2, 139.8, 131.4, 131.1, 129.7, 128.9,
125.7, 124.6, 123.4, 122.8, 120.7, 118.8, 110.8, 109.2, 60.4,
18.8. Anal. calc. for C H BrN O S (%): C, 55.88; H, 3.26;
3
(
s, 3H, C8-CH ), 4.06 (s, 1H, C4-CH eNH ), 4.58 (s, 2H, C4-
3 2
1
3
CH ), 7.35e8.48 (m, 10H, Ar-H), 8.80 (s, 1H, NHCO);
C
NMR (75 MHz, CDCl , d ppm): 174.3, 161.3, 159.7, 156.6,
2
23 16
3 3
N, 8.50; found (%): C, 55.50; H, 3.06; N, 8.21.
3
1
1
1
1
53.8, 150.7, 141.8, 139.6, 136.4, 132.2, 131.4, 129.7, 128.1,
25.6, 124.1, 123.9, 122.7, 120.6, 118.4, 111.2, 108.7, 60.2,
8.4. Anal. calc. for C H N O S (%): C, 66.49; H, 4.12; N,
4.1.8. 4-{[4-(6,8-Dibromo-2-oxo-2H-chromen-3-yl)-thiazol-
2-ylamino]-methyl}-6-chloro-1H-quinoline-2-one (25)
Pale yellow solid (ethanol þ dioxan); yield: 80%; m.p. 158e
2
3 17 3 3
0.11; found (%): C, 66.80; H, 4.38; N, 9.80.
ꢁ
ꢂ1
1662 cm
C]O
1
60 C; FAB-MS: 594 (M þ 1); IR (KBr): n
ꢂ1
ꢂ1
4
.1.5. 4-{[4-(6-Bromo-2-oxo-2H-chromen-3-yl)-thiazol-2-
(amide),
nNH3419 cm
n
1722 cm
(lactone),
n
C]N1616 cm
,
H NMR (300 MHz,CDCl , d ppm): 4.10
C]O
ꢂ1
1
ylamino]-methyl}-6-chlorol-1H-quinoline-2-one (22)
Yellow solid (methanol); yield: 82%; m.p. 148e150 C;
;
(s, 1H, C4-CH eNH ), 4.68 (s, 2H, C4-CH ), 7.38e8.20
3
ꢁ
2
2
ꢂ1
13
(m, 8H, Ar-H), 8.76 (s, 1H, NHCO); C NMR (75 MHz,
FAB-MS: 515 (M þ 1); IR (KBr): n
1672 cm (amide),
ꢂ1
C]O
ꢂ1
ꢂ1
n
1721 cm (lactone), n
H NMR (300 MHz, CDCl , d ppm): 4.18 (s, 1H, C4-CH e
1610 cm , nNH3439 cm ;
CDCl , d ppm): 174.2, 162.1, 159.8, 155.4, 153.3, 150.8,
3
C]O
C]N
1
142.2, 140.1, 136.6, 132.8, 131.2, 128.7, 125.6, 124.4, 122.8,
122.6, 122.1, 120.7, 118.1, 111.4, 108.7, 61.1. Anal. calc. for
C H Br ClN O S (%): C, 44.51; H, 2.04; N, 7.08; found
3
2
NH ), 4.68 (s, 2H, C4-CH ), 7.32e8.48 (m, 9H, Ar-H), 8.75
2
1
3
(
s, 1H, NHCO); C NMR (75 MHz, CDCl , d ppm): 173.8,
3
22 12
2
3 3
1
1
1
5
61.8, 159.4, 155.3, 153.8, 150.7, 142.4, 139.6, 136.2, 132.2,
31.4, 128.7, 125.7, 124.9, 124.1, 122.7, 122.2, 120.4, 119.2,
11.2, 108.9, 60.4. Anal. calc. for C H ClBrN O S (%): C,
(%): C, 44.22; H, 2.01; N, 6.88.
2
2
13
3
3
4.1.9. 4-{[4-(6,8-Dibromo-2-oxo-2H-chromen-3-yl)-thiazol-
2-ylamino]-methyl}-7-chloro-1H-quinoline-2-one (26)
Yellow solid (methanol); yield: 75%; m.p. 148e150 C;
1.33; H, 2.55; N, 8.16; found (%): C, 51.08; H, 2.20; N, 8.60.
ꢁ
ꢂ1
4
.1.6. 4-{[4-(6-Bromo-2-oxo-2H-chromen-3-yl)-thiazol-2-
FAB-MS: 594 (M þ 1); IR (KBr): n
1655 cm (amide),
ꢂ1
C]O
ꢂ1
ꢂ1
ylamino]-methyl}-7-chloro-1H-quinoline-2-one (23)
n
1
1720 cm (lactone), n
1615 cm , nNH3416 cm ;
C]O
C]N
Yellow solid (ethanol þ dioxan); yield: 78%; m.p. 155e
H NMR (300 MHz, CDCl , d ppm): 4.16 (s, 1H, C4-CH e
3 2
ꢁ
ꢂ1
1
57 C; FAB-MS: 515 (M þ 1); IR (KBr): n
1652 cm
NH ), 4.66 (s, 2H, C4-CH ), 7.38e8.20 (m, 8H, Ar-H), 8.79
2
C]O
ꢂ1
ꢂ1
13
(s, 1H, NHCO); C NMR (75 MHz, CDCl , d ppm): 174.6,
(
amide), n 1605 cm , nNH
422 cm ; H NMR (300 MHz, CDCl , d ppm): 4.10 (s, 1H,
1733 cm
(lactone), n
C]O
1
C]N
3
ꢂ1
3
162.0, 159.8, 155.8, 153.3, 150.7, 142.3, 139.8, 138.0,
136.8, 132.6, 131.4, 129.0, 125.8, 124.8, 122.7, 122.1,
120.8, 118.7, 111.2, 108.9, 60.4. Anal. calc. for
C H Br ClN O S (%): C, 44.51; H, 2.04; N, 7.08; found
3
C4-CH eNH ), 4.66 (s, 2H, C4-CH ), 7.29e8.48 (m, 9H, Ar-
2
2
1
3
H), 8.76 (s, 1H, NHCO); C NMR (75 MHz, CDCl , d ppm):
3
1
1
1
74.1, 161.7, 159.8, 155.8, 153.4, 150.8, 142.1, 139.7, 136.7,
32.4, 131.8, 128.4, 125.7, 125.1, 124.4, 122.8, 122.1, 120.6,
18.8, 111.8, 109.3, 60.1. Anal. calc. for C H ClBrN O S
2
2
12
2
3 3
(%): C, 44.12; H, 1.92; N, 6.96.
2
2
13
3 3
(%): C, 51.33; H, 2.55; N, 8.16; found (%): C, 51.10; H, 2.31;
N, 8.24.
4.1.10. 4-{[4-(6,8-Dibromo-2-oxo-2H-chromen-3-yl)-thiazol-
2-ylamino]-methyl}-8-methyl-1H-quinoline-2-one (27)
Pale yellow solid (ethanol); yield: 74%; m.p. 147e149 C;
ꢁ
ꢂ1
4
.1.7. 4-{[4-(6-Bromo-2-oxo-2H-chromen-3-yl)-thiazol-2-
FAB-MS: 574 (M þ 1); IR (KBr): n
1672 cm (amide),
ꢂ1
C]O
ꢂ1
ꢂ1
ylamino]-methyl}-8-methyl-1H-quinoline-2-one (24)
Yellow solid (methanol); yield: 78%; m.p. 150e152 C;
n
1723 cm (lactone), n
1618 cm , nNH3409 cm ;
C]O
C]N
ꢁ
1
H NMR (300 MHz, CDCl , d ppm): 2.52 (s, 3H, C8-CH ),
3 3
ꢂ1
FAB-MS: 495 (M þ 1); IR (KBr): nC]O1678 cm (amide),
4.12 (s, 1H, C4-CH eNH ), 4.70 (s, 2H, C4-CH ), 7.40e8.22
2 2

1276
R.G. Kalkhambkar et al. / European Journal of Medicinal Chemistry 42 (2007) 1272e1276
1
3
(
CDCl , d ppm): 174.8, 161.0, 160.1, 156.8, 153.4, 151.2,
m, 8H, Ar-H), 8.82 (s, 1H, NHCO); C NMR (75 MHz,
5. Conclusion
3
1
1
49.6, 141.8, 139.6, 131.5, 131.0, 129.8, 128.6, 125.6, 124.8,
23.9, 122.4, 120.3, 118.7, 111.3, 109.6, 61.2, 18.4. Anal.
It can be seen that amongst the test compounds substitution
at position 7 of the carbostyril increases both analgesic and
anti-inflammatory activities and 6,8-dibromo substitutions on
coumarin favors higher analgesic and anti-inflammatory activ-
ity. In general, test compounds are non-toxic up to
calc. for C H Br N O S (%): C, 48.19; H, 2.64; N, 7.33;
2
found (%): C, 47.90; H, 2.20; N, 7.06.
3
15
2 3 3
ꢂ1
4
4
.2. Pharmacology
1000 mg kg body weights of the animals. And show reason-
able anti-inflammation activity and clearly very good analge-
sic activity. It is important to note that these are slow acting
anti-inflammation agents, which can be easily degradable in
the metabolic system after 24 h. Further studies are required
to establish their exact mechanism of action.
.2.1. Acute toxicity studies
The acute toxicity for all test compounds was carried out in
albino mice weighing 20e25 g [18] which were fasted over-
ꢂ1
night. The dosage was varied 1000e100 mg kg
body
weight. The animals were observed for 24 h for any signs of
acute toxicity such as increased or decreased motor activity,
tremors, convulsion, sedation, lacrimation etc. No mortality
of the animals was observed even after 24 h. Hence the
LD50 cut off value of the test compounds was fixed as
Acknowledgements
The authors thank the University Sophisticated Instrumen-
tation Centre, Karanatak University, Dharwad for IR, NMR
data and Indian Institute Technology Mumbai for FAB-MS.
One of the authors Mr. Rajesh G. Kalkhambkar is Grateful
to Karnatak University and Karanatak Science College Dhar-
wad for the University Research Studentship.
ꢂ1 ꢂ1
1
000 mg kg . So that 100 mg kg i.e., 1/10 of cut off value
was taken as screening dose for the evaluation of anti-inflam-
matory and analgesic activity.
4
.2.2. Analgesic activity
The analgesic activity of test compounds was carried out in
vivo by acetic acid induced writhing method [14]. Albino mice
of either sex were divided into control, standard and different
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[
[
[
[
The groups of six albino rats of either sex were used in each
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0
.5, 1, 2, 3, 4, 8, 12 and 24 h. The results are depicted in Table 3.