Synthesis, analgesic, anti-inflammatory and antibacterial activities of some novel 2-methyl-3-substituted quinazolin-4-(3H)-ones

Article abstract of DOI:10.1248/bpb.26.1711

A series of novel 2-methyl-3-substituted quinazolin-4-(3H)-ones have been synthesized by treating (2-methyl-4-oxo-3H-quinazolin-3-yl)dithiocarbamic acid methyl ester with different amines, the starting material dithiocarbamate was synthesized from anthranilic acid. The compounds synthesized were investigated for analgesic, anti-inflammatory and antibacterial activities. All the test compounds exhibited significant activity, the compounds VA2, VA3 and VA4 shown more potent analgesic activity, and the compounds VA3 and VA4 shown more potent anti-inflammatory activity than the reference compound diclofinac sodium.

Full text of DOI:10.1248/bpb.26.1711

December 2003
Biol. Pharm. Bull. 26(12) 1711—1714 (2003)
1711
Synthesis, Analgesic, Anti-inflammatory and Antibacterial Activities of
Some Novel 2-Methyl-3-substituted Quinazolin-4-(3H)-ones
b
Veerachamy ALAGARSAMY, ,a Gopal MURUGANANTHAN,a and Ramachandran VENKATESHPERUMAL
*
a Medicinal Chemistry Laboratory, J.S.S.College of Pharmacy; Mysore-570 015, India: and b Birla Institute of Technology
and Sciences; Pilani-333 031, India. Received July 10, 2003; accepted September 9, 2003
A series of novel 2-methyl-3-substituted quinazolin-4-(3H)-ones have been synthesized by treating (2-methyl-
4-oxo-3H-quinazolin-3-yl)dithiocarbamic acid methyl ester with different amines, the starting material dithio-
carbamate was synthesized from anthranilic acid. The compounds synthesized were investigated for analgesic,
anti-inflammatory and antibacterial activities. All the test compounds exhibited significant activity, the com-
pounds VA2, VA3 and VA4 shown more potent analgesic activity, and the compounds VA3 and VA4 shown more
potent anti-inflammatory activity than the reference compound diclofinac sodium.
Key words quinazoline; thiourea; pyrimidine; analgesic; anti-inflammatory
Bacterial infections often produce pain and inflammation. (NH), 1700 (CϭO) and 1640 (CϭN); NMR (CDCl3) d: 2.5
In normal practice, two groups of agents (chemotherapeutic, (s, 3H, CH3) 6.9—7.4 (m, 4H, ArH), MS (m/z) 161 (Mϩ).
analgesic and anti-inflammatory) are prescribed simultane- Anal. Calcd for C9H7NO2: C, 67.08; H, 4.34; N, 8.69. Found:
ously. The compounds possessing all three activities are not C, 67.19; H, 4.39; N, 8.62.
common. Quinazolines and condensed quinazolines exhibit
Synthesis of 3-Amino-2-methyl-3H-quinazolin-4-one
potent antimicrobial1) and CNS activities like analgesic,2) A mixture of 2-methyl-benzo[d][1,3]oxazin-4-one 1.61 g
anti-inflammatory3) and anticonvulsant4) activities. In view of (0.01 mol) and hydrazine hydrate 1.5 g (0.03 mol) in ethanol
these facts and to develop our earlier reported 2-phenyl-3- was refluxed for 2 h and cooled. The separated solid was re-
substituted quinazolines series5) and 2,3-disubstituted quina- crystallized from ethanol, yieldϭ76%, mp 140—142 °C; IR
zolines6) that shown good analgesic and anti-inflammatory (KBr) cmϪ1; 3320, 3260 (NH2), 1680 (cyclic CϭO), 1640
1
activities, in the present study we aimed to synthesize some (CϭN) and 1600, (CϭC); H-NMR (CDCl3) d: 2.6 (s, 3H,
2-methyl-3-substituted quinazolin-4(3H)-ones. The title com- CH3) 4.6 (s, 2H, NH2), 6.6—7.2 (m, 4H, ArH); MS (m/z) 175
pounds were synthesized by nucleophilic substitution of (2- (Mϩ). Anal. Calcd for C9H9N3O : C, 61.71; H, 5.14; N,
methyl-4-oxo-3H-quinazolin-3-yl)dithiocarbamic acid methyl 24.00. Found: C, 61.65; H, 5.17; N, 24.16.
ester with variety of amines. The (2-methyl-4-oxo-3H-quina-
Synthesis of (2-Methyl-4-oxo-3H-quinazolin-3-yl)di-
zolin-3-yl)dithiocarbamic acid methyl ester was synthesized thiocarbamic Acid Methyl Ester To a vigorously stirred
by reacting the amino group of 3-amino-2-methyl quinazo- solution of 3-amino-2-methyl-3H-quinazolin-4-one 3.51 g
line with carbondisulphide and dimethyl sulphate. The 3- (0.02 mol) in dimethyl sulfoxide (10 ml) at room temperature
amino-2-methyl quinazoline was synthesized from an- carbondisulphide 1.6 ml (0.026 mol) and sodium hydroxide
thranilic acid (Chart 1). Spectral data (IR, NMR, and mass
spectra) confirmed the structures of the synthesized com-
pounds, the purity of these compounds was ascertained by
microanalysis (Table 1). The synthesized compounds were
tested for their analgesic, anti-inflammatory and antibacterial
activities.
CHEMISTRY
Melting points were determined in open capillary tubes on
a Thomas Hoover apparatus and are uncorrected. IR spectra
were recorded in KBr on a Perkin Elmer-841 grating spec-
trometer (cmϪ1), mass spectra on a varian Atlas CH-7 mass
spectrometer at 70 eV and NMR spectra on a varian A-60 or
EM-360 spectrometer, using tetramethylsilane as internal
standard. Elemental analysis were performed on Carlo erba
1108.
Synthesis of 2-Methyl-benzo[d][1,3]oxazin-4-one
A
mixture of anthranilic acid 1.37 g (0.01 mol) and acetic anhy-
dride 10.2 ml (0.1 mol) was refluxed on gentle flame for 1 h.
The excess of acetic anhydride was distilled off under re-
duced pressure and the residue was dissolved in petroleum
ether and kept aside for 1 h. The solid obtained was filtered
Chart 1. Synthesis of 1-Methyl-3-(2-methyl-4-oxo-3H-quinazolin-3-yl)-
and dried, yieldϭ73%, mp 182 °C; IR (KBr) cmϪ1: 3350 thiourea and Its Derivatives from Anthranilic Acid
To whom correspondence should be addressed. e-mail: samy_veera@yahoo.com
© 2003 Pharmaceutical Society of Japan

1712
Vol. 26, No. 12
Table 1. Physical Data for 1-Substituted-3-(2-methyl-4-oxo-3H-quinazolin-3-yl)thioureas
Compound code
R
Molecular formulaa)
Molecular weightb)
mp (°C)
Yield (%)
VA1
VA2
VA3
–NHCH3
–N(CH3)2
–N(C2H5)2
C11H12N4OS
C12H14N4OS
C14H18N4OS
248
262
290
151—153
189—192
201—203
69
77
70
VA4
VA5
VA6
C14H16N4OS
C14H16N4O2S
C14H17N5OS
288
304
303
196—199
215—219
226—229
65
81
69
VA7
VA8
C17H16N4O2S
C16H13N5O3S
340
355
256—258
261—262
75
69
VA9
C16H13N4OSCl
C22H18N4OS
344
386
237—240
246—247
72
76
VA10
–N(C6H5)2
a) All Compounds gave satisfactory elemental analysis (Ϯ0.4% of theoritical values). b) Molecular weight determination by mass spectra.
1.2 ml (20 mol solution) were added drop wise during (1% carboxyl methyl cellulose as vehicle) in the same route
30 min, it was allowed to stirr for 30 min more. Dimethyl sul- of administration. Each group consisted of six animals.
phate 2.5 g (0.02 mol) was added at 5—10 °C, stirring was
Animals The animals were procured from “National Bi-
continued for 2 h and the reaction mixture was poured into ological Center”, Madurai, India, and were maintained in
ice water, the solid, so obtained was filtered, washed with colony cages at 25Ϯ2 °C, relative humidity of 45—55%,
water, dried and recrystallized from ethanol, yieldϭ71%, mp maintained under 12 h light and dark cycle and were fed with
103—106 °C, IR (KBr) cmϪ1: 3260 (NH), 1690 (cyclic standard animal feed. All the animals were acclimatized for a
1
CϭO), 1600 (CϭN) and 1130 (CϭS); H-NMR (CDCl3) d: week before use.
2.9—3.0 (s, 3H, CH3), 3.2—3.3 (s, 3H, CH3), 6.9—7.3 (m,
Analgesic Activity7,8) Test for analgesic activity was
4H, ArH), 8.6—8.7 (s, 1H, NH); MS (m/z) 265 (Mϩ). Anal. performed by tail-flick technique using Wistar albino mice
Calcd for C11H11N3OS2: C, 49.80; H, 4.15; N, 15.84. Found: (25—35 g) of either sex selected by random sampling tech-
C, 49.61; H, 4.21; N, 15.93.
nique Diclofenac sodium at a dose level of 10 mg/kg and
Synthesis of 1-Methyl-3-(2-methlyl-4-oxo-3H-quinazo- 20 mg/kg was administered orally as reference drug for com-
lin-3-yl)thiourea (VA1) A mixture of (2-methyl-4-oxo-3H- parison. The test compounds at two dose levels (10,
quinazolin-3-yl)dithiocarbamic acid methyl ester 2.65 g 20 mg/kg) were administered orally. The reaction time was
(0.01 mol) and methylamine 0.62 g (0.02 mol) in N,N-di- recorded at 30 min, 1, 2 and 3 h after the treatment. The cut-
methylformamide (20 ml) was refluxed for 19 h cooled and off time was 10 s. The percent analgesic activity (PAA) was
poured into ice water, the solid obtained was filtered, dried calculated by the following formula,
and recrystallized from ethanol, yieldϭ69%, mp 151—
153 °C, IR (KBr) cmϪ1: 3260 (NH), 1680 (cyclic CϭO),
T2ϪT1
PAAϭ
ϫ100
1
10ϪT1
1600 (CϭN), 1310 (C–N), 1140 (CϭS); H-NMR (CDCl3)
d: 2.2—2.4 (s, 3H, CH3), 3.1—3.3 (s, 3H, –N–CH3), 6.3—
6.7 (m, 4H, ArH), 8.4—8.5 (s, 1H, NH); MS (m/z) 248 (Mϩ).
Anal. Calcd for C11H12N4OS, C, 53.22; H, 4.83; N, 22.58.
Found: C, 53.26; H, 4.76; N, 22.35. Adopting the same pro-
cedure compounds VA2—VA10 were synthesized.
Where T1 is the reaction time(s) before treatment, T2 is the
reaction time(s) after treatment.
Anti-inflammatory Activity Anti-inflammatory activity
was performed by carrageenan-induced paw oedema test in
rats.9) Diclofenac sodium 10, 20 mg/kg was administered as
standard drug for comparison. The test compounds were ad-
ministered at two dose levels (10, 20 mg/kg). The paw vol-
umes were measured using the mercury displacement tech-
nique with the help of a plethysmograph immediately before
and 30 min, 1, 2 and 3 h after carrageenan injection. The per-
cent inhibition of paw oedema was calculated by using the
following formula,
PHARMACOLOGY
The synthesized compounds were evaluated for analgesic,
anti-inflammatory and antimicrobial activities. Student-t-test
was performed for all the activities to ascertain the signifi-
cance of the exhibited activities. The test compounds and the
standard drugs were administered in the form of a suspension

December 2003
1713
percent inhibition Iϭ100[1Ϫ(aϪx)/(bϪy)]
with the increased lipophilicity (dimethyl group) compound
VA2 shown increased activity. Further increase in liphopilic-
ity (diethyl group) VA3 led to further increase in activity.
Substitution with alicyclic amines VA4 retains the activity.
Placement of alicyclic amines with additional heteroatoms
VA5, VA6 led to decrease in activity. Aromatic substitution
VA7 to VA10 shown still lower activity. The compounds with
aliphatic substitution (VA1—VA4) shown the better activity.
The compound VA4 was found to be the most active anal-
gesic agent and it is more potent than diclofenac sodium and
our earlier reported 2-phenyl-3-substituted quinazolines.
The anti-inflammatory activity data (Table 3) reveled that
all the test compound protected rats from carrageenan-in-
duced inflammation and are more potent than our earlier re-
ported 2-phenyl-3-subtituted quinazolines. The compounds
VA3 and VA4 showed more anti-inflammatory activity than
that of diclofenac sodium, while the compound VA2 is
equipotent with diclofenac sodium.
The result of antibacterial activity indicates that all the test
compounds exhibited moderate activity against the tested
bacteria. The compound VA3 showed good activity against
B. subtilis, E. tarda and S. aureus; The compound VA8 ex-
hibited good activity against B. subtilis and S. aureus; and
the compound VA9 exhibited good activity against P. vul-
garis, K. pneumoniae and S. aureus.
The results of analgesic and anti-inflammatory activities
indicate that the replacement of C-2 phenyl group of 2-
phenyl-3-substituted quinazolines by C-2 methyl group
showed increase in activity. However the potency is lesser
than our earlier reported 2, 3-disubstituted quinazolines.
Hence further structural modification is planned to increase
not only the analgesic and anti-inflammatory activities also
the antibacterial activity.
Where x is the mean paw volume of rats before the adminis-
tration of carrageenan and test compounds or reference com-
pound (test group), a is the mean paw volume of rats after
the administration of carrageenan in the test group (drug
treated), b is the mean paw volume of rats after the adminis-
tration of carrageenan in the control group, y is the mean
paw volume of rats before the administration of carrageenan
in the control group.
Antibacterial Activity Evaluation of antibacterial activ-
ity by agar dilution method.10) The standard strains were pro-
cured from the American Type Culture Collection (ATCC),
Rockville, U.S.A., and the pathological strains were procured
from the Department of Microbiology, Madurai Medical Col-
lege and Research Institute, Madurai, India. The antibacterial
activity of the synthesized compounds were screened against
the following bacterial strains: Proteus vulgaris ATCC 9484,
Escherichia coli, Klebsiella pneumoniae ATCC 13883,
Edwardsiella tarda, Staphylococcus aureus, Bacillus subtilis
ATCC 6051. All bacteria were grown on Muller–Hinton
Agar (Hi-media) plates (37 °C, 24 h) then the minimum in-
hibitory concentration (MIC) was considered to be the lowest
concentration that completely inhibited the growth on agar
plates, disregarding a single colony or faint haze caused by
the inoculums. The MIC of the test compounds were com-
pared with the reference drug norfloxacin.
RESULTS AND DISCUSSION
The analgesic activity data reveals that all the test com-
pounds exhibited significant activity (Table 2). The com-
pound VA1 with methyl substitution showed good activity;
Table 2. Analgesic Activity (Tail-Flick Technique)
Percentage analgesic activity
Compound
Dose (mg/kg)
code
30 min
1 h
2 h
3 h
VA1
VA2
VA3
VA4
VA5
VA6
VA7
VA8
VA9
VA10
10
20
10
20
10
20
10
20
10
20
10
20
10
20
10
20
10
20
10
20
32Ϯ0.96**
45Ϯ0.16*
37Ϯ0.91*
49Ϯ0.66**
39Ϯ0.52**
52Ϯ0.46**
41Ϯ0.49**
53Ϯ0.42**
31Ϯ0.43**
43Ϯ0.65**
30Ϯ0.18*
43Ϯ0.76**
28Ϯ0.49**
41Ϯ0.83**
29Ϯ0.28**
42Ϯ0.55**
27Ϯ0.17**
37Ϯ0.18***
22Ϯ0.11**
35Ϯ0.54*
2Ϯ0.35
35Ϯ0.63*
51Ϯ0.39**
41Ϯ0.53*
58Ϯ0.45**
43Ϯ0.51*
60Ϯ0.48**
45Ϯ0.77**
62Ϯ0.63***
32Ϯ0.73***
48Ϯ0.68**
31Ϯ0.48**
48Ϯ0.78**
30Ϯ0.79*
45Ϯ0.53*
30Ϯ0.76*
47Ϯ0.49**
29Ϯ0.48**
40Ϯ0.49*
24Ϯ0.49*
36Ϯ0.28**
6Ϯ0.49
39Ϯ0.21*
57Ϯ0.41**
47Ϯ0.43***
61Ϯ0.68**
49Ϯ0.44**
64Ϯ0.83*
50Ϯ0.57*
65Ϯ0.79*
35Ϯ0.72**
51Ϯ0.98*
35Ϯ0.19**
49Ϯ0.76*
32Ϯ0.82**
46Ϯ0.68***
35Ϯ0.47***
51Ϯ0.72**
31Ϯ0.18***
41Ϯ0.58**
26Ϯ0.44***
38Ϯ0.85**
4Ϯ0.59
30Ϯ0.19***
38Ϯ0.11***
33Ϯ0.56**
45Ϯ0.46*
35Ϯ0.42*
46Ϯ0.49**
36Ϯ0.11**
48Ϯ0.26*
27Ϯ0.49***
35Ϯ0.68***
24Ϯ0.98**
37Ϯ0.43*
20Ϯ0.19**
33Ϯ0.68***
23Ϯ0.78**
36Ϯ0.94*
17Ϯ0.12***
27Ϯ0.48**
16Ϯ0.49***
24Ϯ0.65*
Control
4Ϯ0.91
Diclofenac
10
20
35Ϯ0.51*
47Ϯ0.46*
40Ϯ0.91**
56Ϯ0.83***
44Ϯ0.16*
60Ϯ0.54**
32Ϯ0.45**
41Ϯ0.61*
Each value represents the meanϮS.D. (nϭ6). Significance levels pϽ0.5, pϽ0.01 and
pϽ0.001 as compared with the respective control.

1714
Vol. 26, No. 12
Table 3. Anti-inflammatory Activity (Carrageenan-Induced Rat Paw Oedema Method)
Percentage protection
Compound
Dose (mg/kg)
code
30 min
1 h
2 h
3 h
VA1
VA2
VA3
VA4
VA5
VA6
VA7
VA8
VA9
VA10
10
20
10
20
10
20
10
20
10
20
10
20
10
20
10
20
10
20
10
20
24Ϯ0.25**
36Ϯ0.17**
31Ϯ0.46**
42Ϯ0.55*
32Ϯ0.17*
45Ϯ0.45**
35Ϯ0.53**
44Ϯ0.49*
23Ϯ0.36**
35Ϯ0.42*
24Ϯ0.17**
34Ϯ0.32**
21Ϯ0.33**
26Ϯ0.52*
20Ϯ0.97**
24Ϯ0.52**
23Ϯ0.42**
28Ϯ0.56**
22Ϯ0.17**
25Ϯ0.39**
5.13Ϯ0.29
29Ϯ0.19**
41Ϯ0.25***
27Ϯ0.42**
41Ϯ0.86*
38Ϯ0.28*
52Ϯ0.48**
39Ϯ0.28**
54Ϯ0.36*
38Ϯ0.67*
55Ϯ0.61**
27Ϯ0.55***
39Ϯ0.39**
26Ϯ0.35**
37Ϯ0.38**
23Ϯ0.27**
34Ϯ0.55*
24Ϯ0.74*
36Ϯ0.29*
26Ϯ0.49*
35Ϯ0.48**
25Ϯ0.46*
35Ϯ0.27***
6.12Ϯ0.27
32Ϯ0.13*
51Ϯ0.56**
33Ϯ0.41*
50Ϯ0.48*
41Ϯ042**
56Ϯ0.36**
46Ϯ0.29**
60Ϯ0.53**
44Ϯ0.39**
60Ϯ0.48**
29Ϯ0.84*
46Ϯ0.38**
28Ϯ0.28*
46Ϯ0.37***
30Ϯ0.57**
37Ϯ0.38**
33Ϯ0.57*
37Ϯ0.62*
34Ϯ0.57*
39Ϯ0.29*
32Ϯ0.43*
35Ϯ0.36*
5.79Ϯ0.32
36Ϯ0.56**
56Ϯ0.49*
25Ϯ0.17**
37Ϯ0.26*
36Ϯ0.37**
44Ϯ0.43**
35Ϯ0.18**
45Ϯ0.38*
35Ϯ0.56***
43Ϯ0.27*
26Ϯ0.17**
33Ϯ0.25**
21Ϯ0.17**
36Ϯ0.29**
24Ϯ0.58***
29Ϯ0.26*
23Ϯ0.54*
25Ϯ0.25*
26Ϯ0.49**
31Ϯ0.72**
22Ϯ0.26**
29Ϯ0.73**
3.29Ϯ0.51
30Ϯ0.72***
39Ϯ0.45***
Control
Diclofenac
10
20
Each value represents the meanϮS.D. (nϭ6). Significance levels pϽ0.5, pϽ0.01 and
pϽ0.001 as compared with the respective control.
Table 4. Antibacterial Activity (Agar Dilution Method) MIC Values REFERENCES
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Compound
code
E. coli P. vulgaris K. pneumoniae B. subtilis E. tarda S. aureus
VA1
VA2
19.53
156.25
19.53
78.12
39.06
156.25
19.06
156.25
39.06
156.25
0.60
156.25
39.06
78.12
156.25
156.25
19.06
78.12
78.12
9.76
78.12
78.12
19.53
78.12
19.53
78.12
78.12
19.53
9.76
39.06
19.53
9.76
78.12
156.25
9.76
78.12
39.06
9.76
VA3
VA4
156.25
78.12
19.06
19.06
9.76
39.06
156.25
78.12
156.25
19.53
78.12
78.12
9.76
19.53
78.12
19.06
39.06
9.76
VA5
VA6
VA7
VA8
VA9
19.53
19.53
4.88
9.76
VA10
Norfloxacin
78.12
2.44
156.25
0.60
39.06
1.22
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