Synthesis, analgesic, anti-inflammatory, and antimicrobial activity of some novel pyrimido[4,5-b]quinolin-4-ones

Article abstract of DOI:10.1016/j.bmc.2007.12.012

Novel series of pyrimido[4,5-b]quinolines (3a-c), triazolo[4′,3′:1,2]pyrimido[4,5-b]-quinolines (7a-e, 9, and 14), tetrazolo[4′,3′:1,2]pyrimido[4,5-b]quinolin-5-one (13), [1,3]-pyrazolo[3′,2′:1,2]pyrimido[4,5-b]quinolines (12a and 12b), and 2-pyrazolyl-py

Full text of DOI:10.1016/j.bmc.2007.12.012

Available online at www.sciencedirect.com
Bioorganic & Medicinal Chemistry 16 (2008) 3261–3273
Synthesis, analgesic, anti-inflammatory, and antimicrobial
activity of some novel pyrimido[4,5-b]quinolin-4-ones
Abdel-Rahman B. A. El-Gazzar,a,* Mervat M. El-Enanyb and Mahmoud N. Mahmouda
aPhotochemistry Department (Heterocyclic Unit), National Research Centre, Dokki, Giza, Egypt
bOrganic Chemistry Department, Faculty of Pharmacy, Cairo University, Cairo, Egypt
Received 4 October 2007; revised 3 December 2007; accepted 7 December 2007
Available online 14 December 2007
Abstract—Novel series of pyrimido[4,5-b]quinolines (3a–c), triazolo[40,30:1,2]pyrimido[4,5-b]-quinolines (7a–e, 9, and 14), tetrazolo
[40,30:1,2]pyrimido[4,5-b]quinolin-5-one (13), [1,3]-pyrazolo[30,20:1,2]pyrimido[4,5-b]quinolines (12a and 12b), and 2-pyrazolyl-
pyrimido[4,5-b]-quinolines (15, 16a, 16b, and 19) have been synthesized. Some of the new compounds were tested against various
bacteria and fungi species. In addition, the analgesic and anti-inflammatory activities are reported. Compounds 8 and 9a possess
high activity toward the fungi as compared with the reference drug Nystatin. The tested compounds 5 and 8 have moderate
anti-inflammatory activities. Moreover compounds 5, 8, 10, and 16a, have activities higher than the reference drug in peripheral
analgesic activity testing, Compounds 5, 7a, 11a, and 16a have potencies as the reference drug in central analgesic activity testing.
ꢀ 2007 Elsevier Ltd. All rights reserved.
1. Introduction
2. Results and discussion
Since resistance to antimicrobial drugs is widespread,
there is an increasing need for identification of novel
structure leads that may be of use in designing new, po-
tent, and less toxic antimicrobial agents. Imiquimod, Cli-
oquinol, and Enoxacin are antiviral, antifungal, and
antibacterial drugs which contain pyrimidine and quin-
oline rings. Pyrimidoquinoline nuclei have been a source
of great interest to organic, medicinal and materials sci-
entists over many years, which is present in a number of
biologically active organic compounds1–6 which exhibit,
antibacterial,7 anticancer,8 and medicinal,9,10 anti-
inflammatory activities.11,12 Moreover, the increasing
biological importance of pyrimidoquinoline derivatives
particularly in the field of chemotherapy, prompted us
to develop and identify the new molecules as triazol-
o[40,30:1,2]pyrimido-[4,5-b]quinoline, tetrazolo[40,30:1,2]
pyrimido[4,5-b]quinolin-5-one, and [1,3]pyrazolo-[30,20:
1,2]pyrimido[4,5-b]quinoline derived from pyrimido
[4,5-b]quinolin-4-ones in order to investigate the effect
of such structural variation on the anticipated antimi-
crobial, anti-inflammatory, and analgesic activities.
The present work is an extension of our studies on pyr-
idopyrimidone derivatives and their behavior as func-
tional and bifunctional groups.12–16 We now wish to
report the synthesis of various types of functionalized
heterocyclic derivatives and study their biological activ-
ities. Thus, heating under reflux of 6-aminothiouracil 2
with a,b-unsaturated ketones 1 gave 5-aryl-2-thioxo-
2,3,6,7,8,9-hexahydro-1H,4H-pyrimido[4,5-b]quinolin-4-
ones (3a–c) and the non-oxidized form 2-thioxo-5,
10-dihydro-1H,4H-pyrimido[4,5-b]quinolin-4-ones 30a–
c were isolated (Method A). The cyclo-condensation
process depending on the reaction conditions, the pro-
longed reaction time in refluxing dimethylformamide
furnishes the pure oxidation forms (3a–c) in good yield.
Also, the latter pyrimidopyrimidines 3a–c were obtained
by the cyclo-condensation reaction of 6-aminothiouracil
(2) with cyclohexanone and aldehyde (one-pot synthesis)
Method B, as shown in Scheme 1.
Beside the correct values in elemental analyses and spec-
tral data of structures 3 and 30 as shown in Section 3,
structure 3 was established chemically by investigating
its reactivity toward various reagents. Alkylation of an
ethanolic potassium hydroxide solution of 3a with methyl
iodide yielded 5-phenyl-2-methylthio-2,3,6,7,8,9-hexa-
hydro-1H-pyrimido[4,5-b]quinolin-4-one (4). Also, com-
pounds 3a and 4 gaves 2-hydrazino-5-phenyl-2,3,6,7,8,
Keywords: Pyrimido[4,5-b]quinoline; Antimicrobial; Anti-inflamma-
tory; Analgesic activities.
*
Corresponding author. Tel.: +20 237318830; e-mail: profelgazzar@
yahoo.com
0968-0896/$ - see front matter ꢀ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2007.12.012

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A. -R. B. A. El-Gazzar et al. / Bioorg. Med. Chem. 16 (2008) 3261–3273
Ar
O
Ar
N
O
O
H
H
S
H
S
H
S
CHAr
N
N
N
N
Method A
H
N
+
N
H
N
H
H2N
N
H
2
O
1
Ar
O
Ar
O
H
H
S
O
H
S
Method B
N
ArCHO
+ 2
+
+
one-pot
synthesis
N
N
H
N
H
N
H
3
(60-70%)
3'a-c
Ar, a = Phenyl
b = 4-Chlorophenyl
c = 4-Methoxyphenyl
NH2NH2.H2O
MeI
C6H5
O
N
N
C6H5
O
H
NH
NH2
N
N
H
N
N
SCH3
4
5
Scheme 1.
9-hexahydro-1H-pyrimido[4,5-b]quinolin-4-one (5), with
the evolution of hydrogen sulfide or methylmercaptan,
upon treatment with hydrazine hydrate as shown in
Scheme 1.
with acetic acid for long time gave 9b. Also, the 2-hydra-
zino derivative 5 reacted with potassium thiocyanate in
boiling acetic acid to give 3-amino-triazolo[40,
30:1,2]pyrimido[4,5-b]quinoline 10 (Scheme 3).
Meanwhile, stirring compound 3a under reflux with
hydrazonoyl chlorides (6a–e)17,18 in dry chloroform with
a few drops of triethylamine for long time (TLC) affor-
ded 6-phenyl-7,8,9,10-tetrahydro-1,3-substituted-triaz-
olo[40,30:1, 2]pyrimido[4,5-b]quinolin-5-one derivatives
(7a–f) rather than the isomeric structures 70 via removal
of H2S as shown in Scheme 2. Structure 7 as shown in
Scheme 2 was preferred on the basis of the literature that
pyrimidines and fused pyrimidines underwent cycliza-
tion at the N-neighboring to the carbonyl group (N-3
not N-1). Moreover, the infrared spectrum indicated
that the absorption peak for the carbonyl group (imide)
in position 4 shifted by 15–20 cmꢀ1 more than that for
amide.19 1H and 13C NMR spectral data. Thus, 1H
NMR spectrum for the compound 7a, as an example,
showed signals at d 1.72–1.74 (m, 2H, CH2), 1.87–1.89
(m, 2H, CH2), 2.33–2.38 (t, 2H, CH2), 3.13–3.18 (t,
2H, CH2), 7.10–7.25 (m, 2H, phenyl), 7.32–7.54 (m,
9H, phenyl), 7.65–7.68 (m, 2H, phenyl), and 8.38–8.41
(m, 2H, phenyl). The reaction mechanism may proceed
as shown in Scheme 2.
Beside the correct values in elemental analyses, the spec-
tral data of 10 are in agreement with the assigned struc-
ture. The latter reaction of 2-hydrazino with potassium
thiocyanate may be accomplished via the intermediates,
as shown in the considered mechanism (Scheme 4). Also,
compound 5 gave the 2-arylmethylene hydrazone deriv-
atives 11a–c when treated with the appropriate aldehyde
in boiling glacial acetic acid (Scheme 3).
The reaction of 5 with a-haloketones namely, chloroac-
etone or phenacyl bromide in dry xylene, yielded the
respective [1,3]pyrazolo[30,20:1,2]pyrimido[4,5-b]quino-
1
lines (12a and 12b) as shown in Scheme 3. H NMR
spectrum of 12a, as an example, showed signals at d
1.65–1.66 (m, 2H, CH2), 1.80–1.82 (m, 2H, CH2),
2.22–2.23 (t, 2H, CH2), 2.97–2.99 (t, 2H, CH2), 3.23 (s,
3H, CH3), 5.62 (br s, NH2, D2O exchangeable), 7.06–
7.08 (m, 2H, aromatic protons), 7.35–7.45 [m, 3H aro-
matic protons), and 8.10 (s, 1H, pyrazolyl proton). Also,
its IR spectrum displayed absorption bands at 3420 and
1687 cmꢀ1 corresponding to (NH) and (CO) groups,
respectively.
Moreover, 2-hydrazino 5 could be considered as a starting
material for the synthesis of new polynuclear heterocycles
such as azolo-pyrimidoquinolines, pyrimidoquinoline-as-
triazines as well as the synthesis of some pyrazolopyrimi-
do-qinolone derivatives. Thus, heating compound 5 with
aliphatic acids, namely formic or acetic acid, resulted in
the formation of triazolo[40,30:1,2]-pyrimido[4,5-b]quino-
line (9a and 9b), as shown in Scheme 3. On the other hand,
heating compound 5 with acetic acid for 3 h yielded 2-
acetyl-hydrazino derivative 8, which on further heating
Treatment of 5 with nitrous acid at 0 ꢁC led to the for-
mation of 6-phenyl-7,8,9,10-tetrahydrotetrazolo[40,
30:1,2]pyrimido[4,5-b]quinolin-5-one (13) (Scheme 5),
which was in equilibrium with the 2-azido-pyrimi-
do[4,5-b]pyrimidine (130) tautomer. The IR spectrum
of 13 displayed absorption bands at 3243 (NH) and
1700 cmꢀ1 (CO) and characteristic absorption band for
the azido group20 at 2320 cmꢀ1. Aminopyrimidines are
reported in the literature for its biological activities as

A. -R. B. A. El-Gazzar et al. / Bioorg. Med. Chem. 16 (2008) 3261–3273
3263
C6H5
O
H
S
Cl
N
H
N
N
+
R
Ar
N
N
H
6
3a
C6H5
O
C6H5
O
N
H
H
S
N
R
N
S
R
N
N
H
Ar
N
N
N
N
N
Ar
H
C6H5
O
R
C6H5
O
N
SH
Or
Ar
N
N
N
R
N
N
H
N
N
N
N
H
SH
Ar
-HSH
C6H5
O
C6H5
O
R
N
N
N
Ar
N
N
N
R
N
N
N
N
Ar
7
7'
6,7 a, R = Ar = C6H5
6,7 c, R = COCH3, Ar = p-C6H4-NO2
6,7 e, R = COOC2H5, Ar = p-C6H4-CH3
6,7 b, R = COCH3, Ar = p-C6H4-Cl
6,7 d, R = COOC2H5, Ar = C6H5
Scheme 2.
C6H5
O
N
C6H5
O
N
NH2
N
H
N
N
N
NHNHCOCH3
N
N
H
8
10
C6H5
C6H5
O
KSCN
O
AcOH
R
N
N
5
N
N
N
N
H
R
N
N
N
9a,b
ArCHO
acetic acid
NH2
12a,b
a, R = methyl, b, R = phenyl
a, R = H, b, R = Me
C6H5
O
H
N
H
N
a, Ar = phenyl
b, Ar = 4-chlorophenyl
c, Ar = 4-methoxyphenyl
N
N
N
Ar
H
11a-c
Scheme 3.
anticancer, antibacterial, and antimalarial.19 Therefore,
compound 13 was reduced into 2-aminopyrimido[4,5-
b]-pyrimidine (14) by zinc dust and acetic acid.
The 2-hydrazino derivative 5 reacted with b-diketones,
b-ketoesters and b-cyano-esters to form 2-(1-pyrazolyl)
derivatives. Thus, heating compound 5 with each of eth-

3264
A. -R. B. A. El-Gazzar et al. / Bioorg. Med. Chem. 16 (2008) 3261–3273
C6H5
O
C6H5
O
H
H
H
N
N
H
N
+
KSCN
AcOH
NH
N
N
O
N
N
NHNH2
N
H
5
SH
C6H5
C6H5
O
HS
N H
NH2
NH2
N
-H2S
N
N
-AcOK
N
N
N
N
N
N
H
H
10
Scheme 4.
C6H5
O
O
N
C6H5
N
N
N
N H
N
N
N
N3
N
H
13
13`
C6H5
O
N
Zn dust
N H
acetic acid
N
NH2
14
Scheme 5.
ylcyanoacetane, pentane-2,4-dione, and/or 3-chloropen-
tane-2,4-dione yielded the respective 2-(pyrazol-5-one-1-
yl)-6,7,8,9-tetrahydropyrimido[4,5-b]quinolin-4-one (15,
16a, and 16b) (Scheme 6).
pared with the reference drug Nystatin, while the rest
of the compounds showed no activity toward the fungi.
The MIC (minimum inhibitory concentration) of the
most active compounds toward the micro-organisms
showed that the MICs ranged between 20 and 30 lg/
disk. The activity is tested at concentration of 50 lg/
disk. The minimum inhibitory concentrations (MIC)
for compounds with high activity 8, 9b, 10, 12b, 13,
and 16a are presented in Table 2.
Trials to synthesize the pyrimidotriazine derivative 170
by treatment of 5 with chloro acetylchloride in anhy-
drous dioxane were not successful. Instead the 2-chloro-
acetyl-hydrazino derivatives 17 were obtained (Scheme
6). Beside the correct values in elemental analyses, the
1
spectral data (IR, H NMR, Mass spectra) of 17 are
in agreement with the assigned structure (see Section
2.2. Anti-inflammatory activity
3). Finally, compound
5
condensed with ethyl
Anti-inflammatory activity was evaluated by carra-
geenin-induced paw edema test in rats. The Anti-inflam-
matory activity data (Table 3) indicated that,
compounds 8 and 5 show significant anti-inflammatory
activity in descending order in comparison to the control
group, with 50% and 40% potency with respect to indo-
methacin. Compounds 16a and 10 have no anti-inflam-
matory activity.
acetoacetate, upon heating in boiling ethanol, to afford
5-phenyl-2-(ethyl acetoacetatehydrazone)-6,7,8,9-tetra-
hydropyrimido[4,5-b]quinolin-4-one (18), which could
be cyclized either by prolonged heating in ethanol or
by heating in ethanolic sodium ethoxide solution to give
5-phenyl-2-(3-methyl-4H-pyrazol-5-one-1-yl)-6,7,8,9-tetra-
hydropyrimido[4,5-b]quinolin-4-one (19).
2.1. Antimicrobial activity
2.3. Analgesic activity
From the data obtained in Table 1, it is clear that all the
tested compounds were found to be active against G
ꢀve) and G (+ve) bacteria compared to the reference
drug Nalidixic acid. On the other hand, compounds 8
and 9b possess high activity toward the fungi as com-
Test for analgesic activity was performed by Turner21
and Collier22 technique using Swiss albino mice. The re-
sults of analgesic activity (Table 4) indicated that some
of the tested compounds show central analgesic activity
(Hot-plate test), especially compounds 11a, 5, 7a, 16a,

A. -R. B. A. El-Gazzar et al. / Bioorg. Med. Chem. 16 (2008) 3261–3273
3265
C6H5
O
C6H5
O
N
N H
N
NH
N
N
N
NH-NHCOCH2Cl
N
17
19
CH3
O
ClCH2COCl
C6H5
O
C6H5
O
O
N
N
NH
NH
CH3
NH-N=CCH2COOC2H5
5
N
N
N
N
H
17'
C6H5
18
O
C6H5
O
N H
N H
N
N
N
N
N
N
N
N
CH3
H3C
NH2
HO
a, X = H
b, X = Cl
X
15
16a,b
Scheme 6.
Table 1. Preliminary antimicrobial activity test for tested compounds
Compound
Microorganism inhibition zone diameter (mm)
Gram ꢀve bacteria Gram +ve bacteria
Escherichia coli Klebsiella pneumonia Pseudomonas aeruginosa Staphylococcus aureus Candida albicans Candida gabrata
Fungi
13
16a
18
19
20
20
12
13
20
13
21
15
—
16
20
20
18
14
13
22
14
22
18
—
25
22
22
21
22
15
15
22
14
23
14
—
25
17
21
21
19
13
11
21
13
19
16
—
25
—
9
—
9
9b
18
17
—
—
—
—
—
7
13
16
—
—
—
—
—
7
8
3a
5
10
3b
12b
11a
Nystastin
20
—
19
—
Nalidixic acid 24
Inhibition zone, 6–10 mm slight activity, 11–15 mm moderate activity, more than 15 mm high activity.
Table 2. The minimum inhibitory concentration (MIC)
Compound
Escherichia coli
Klebsiella pneumonia
Pseudomonas aeruginosa
Staphylococcus aureus
Candida albicans
13
16a
9b
8
30
30
20
20
30
20
30
30
20
20
30
20
30
30
20
20
30
20
30
30
20
20
30
20
—
—
50
50
—
—
10
12b
3a, 12b, 9b and 13 in descending order, where compound
11a showed activity equal to acetylsalicylic acid. Com-
pounds 10 and 8 have no central analgesic activity. Also,
Table 5 shows that, compounds 8, 16a, 10, 5, 12b, 3a,
and 11a were found to have significant peripheral anal-
gesic activity in descending order, where the first four

3266
A. -R. B. A. El-Gazzar et al. / Bioorg. Med. Chem. 16 (2008) 3261–3273
Table 3. Acute inflammation in rat using Plethysmometer
Group
1 h
Edema rate (%)
34.75 3.12b
31.08 1.84b (10.5) 14.5
25.73 1.24ab (25.9) 45.5
24.15 0.89ab (30.5) 53.5
31.23 2.46b (10.1) 17.7
2 h
Pot. (%) Edema rate (%)
52.96 1.87b
3 h
Pot. (%) Edema rate (%)
81.77 3.28b
81.73 4.11b (0.1)
4 h
Pot. (%) Edema rate (%)
Pot. (%)
Control
0
0
0
0.1
91.57 4.53b
90.86 2.96b (0.8)
0
1.7
b
16a
8
52.49 1.88 (0.9) 1.5
40.89 3.08ab (22.8) 39.2
62.25 4.18ab (23.9) 55.9
63.96 1.91ab (21.8) 51.1
71.61 3.33ab (21.8) 46.9
74.52 3.29ab (18.6) 40.1
b
41.95 2.00 (20.8) 35.7
5
10
b
52.31 4.79 (1.2) 2.1
22.15 0.80a (58.2) 100
79.47 2.33b (2.8)
6.6
46.91 5.00a (42.6) 100
82.88 1.87b (9.5)
20.5
49.07 2.74a (46.4) 100
Indom-ethacin 14.95 0.93a (56.9) 100
Values represent means SE of six animals for each group.
Each value in parentheses indicates the percentage inhibition rate.
The potency (pot.) was calculated compared to the reference drug indomethacin.
a P < 0.05, statistically significant from control. One-way ANOVA (Dunnett’s test).
b P < 0.05, statistically significant from indomethacin. One-way ANOVA (Dunnett’s test).
Table 4. Central analgesic activity (hot-plate test)
Group
Reaction time (s)
0 min
30 min
60 min
90 min
8.51 0.40b
Control
7a
6.23 0.31
8.16 0.56
6.90 0.62
7.24 0.59
7.40 0.37
6.26 0.41
7.64 0.20
5.38 0.30
6.42 0.62
7.08 0.92
7.08 0.12
6.49 0.40
7.10 0.36b
9.84 0.28a
9.16 0.57a
10.08 0.78a
9.42 0.45a
8.68 0.48
7.54 0.26b
5.14 0.26b
8.62 0.34
8.93 0.74
8.65 0.87
10.03 0.12a
7.60 0.41b
11.62 0.57b
10.78 0.45a
12.52 0.82a
11.41 0.29a
8.80 0.52
10.61 0.60a
6.74 0.28b
8.06 0.56b
10.15 1.20
10.98 0.91a
11.39 0.53a
11.88 0.47b
10.08 0.24b
12.68 0.61a
10.67 0.59ab
10.40 0.18b
12.00 0.36a
7.62 0.60b
9.22 0.47b
11.50 0.40a
11.12 0.75ab
13.15 0.38a
13
11a
12b
9b
5
10
8
16a
3a
Acetyl salicylic acid
Values represent means SE of five animals for each group.
a P < 0.05, statistically significant from control. One-way ANOVA (Dunnett’s test).
b P < 0.05, statistically significant from ASA. One-way ANOVA (Dunnett’s test).
Table 5. Peripheral analgesic activity (Writhing test)
3. Experimental
Group
No. of writhes/
20 min
Protection
(%)
Potency
(%)
3.1. Chemistry
Control
7a
48.0 2.24b
45.8 2.91b
41.3 2.39b
31.3 2.48ab
30.2 1.69a
45.2 1.77b
22.6 1.96a
20.6 1.81a
19.0 1.18a
19.6 0.51a
31.0 1.58ab
23.2 1.36a
0
4.6
0
8.89
Melting points were determined on griffin apparatus.
1
The H NMR and 13C NMR spectra were recorded on
13
11a
14.0
34.9
37.1
5.8
27.07
67.51
71.76
11.2
JEOL EX-270 run for HNMR at 270 MHz and run
for CNMR at 67.5 MHz: or on JEOL ECA-500 run
for HNMR at 500 MHz and run for CNMR at
125 MHz and JEOL JNM-LA-400 FT NMR Spectrom-
eter (Universita¨t Konstanz, Germany) and chemical
shifts were expressed as d values against Si(CH3)4 as
internal standard. IR spectra were recorded as KBr pel-
lets on a Perkin-Elmer 1430 spectrometer (National Re-
search Centre and Department of Chemistry, Cairo
University). Mass Spectra were run at 70 eV on HP-
5988A Mass spectrometer, Micro-analytical Centre,
Cairo University. The biological activities were screened
in Pharmacological Unit, National Research Centre,
Egypt.
12b
9b
5
10
52.9
57.1
60.4
59.2
35.4
51.7
102.32
110.44
116.83
114.51
68.47
100
8
16a
3a
Acetylsalicylic acid
Values represent means SE of six animals for each group.
a P < 0.05, statistically significant from control. One-way ANOVA
(Dunnett’s test).
b P < 0.05, statistically significant from aspirin. One-way ANOVA
(Dunnett’s test).
compounds showed activity superior to acetylsalicylic
acid.
3.1.1. 5-Aryl-2-thioxo-2,3,5,6,7,8,9,10-octahydro-1H-
pyrimido[4,5-b]quinolin-4-ones (30a–c): General proce-
dure. A mixture of compound 1 (0.01 mol) and 6-amino-
thiouracil (2) (0.01 mol) was refluxed in 50 mL
dimethylformamide for 8–10 h (under TLC control).
These findings represent an important advantage to
compounds 5 and 8 as anti-inflammatory with high
analgesic activity equal to that of acetylsalicylic acid.

A. -R. B. A. El-Gazzar et al. / Bioorg. Med. Chem. 16 (2008) 3261–3273
3267
The reaction mixture was cooled, poured onto water
(100 mL). The precipitate was filtered off, dried, and
crystallized from the appropriate solvent to produce
30a–c.
off, washed with ethanol and dried, and crystallized
from dimethylformamide.
3.1.2.3. 5-Phenyl-2-thioxo-2,3,6,7,8,9-hexahydro-1H-
pyrimido[4,5-b]quinolin-4-one (3a). The compound was
obtained from 1a (0.01 mol), as a yellow powder, crys-
tallized from ethanol/dioxane (2:1) in a 75% yield, mp
310 ꢁC (melted); IR, cmꢀ1; 3370 (br s, NH), 3047 (CH
aryl), 2919 (CH alkyl), 1688 (CO), 1615 (C@N). 1H
NMR (DMSO-d6, d ppm); 1.59–1.66 (m, 2H, CH2),
1.75–1.81 (m, 2H, CH2), 2.21 (t, 2H, CH2), 2.90 (t,
2H, CH2), 7.07–7.09 (m, 2H, phenyl), 7.32–7.39 (m,
3H, phenyl), and 11.20, 12.12 (2br s, 2NH, D2O
exchangeable); 13C NMR (DMSO-d6, d ppm); 21.98,
26.38, 33.07, 39.06 (4C, 4CH2), 107.6, 127.0, 127.1,
127.1, 127.9, 137.4, 149.8, 151.5, 158.5 (9C, sp2 carbon
atoms with two asymmetric carbon atoms) and 163.4
(CO), 175.5 (CS); MS m/z 309 (M+, 100); Anal.
C17H15N3OS (309.4); requires: C, 65.99; H, 4.89; N,
13.58. Found: C, 66.03; H, 4.90; N, 13.62.
3.1.1.1. 5-Phenyl-2-thioxo-2,3,5,6,7,8,9,10-octahydro-
1H-pyrimido[4,5-b]quinolin-4-one (30a). The compound
was obtained from 1a (0.01 mol), as a pale yellow pow-
der, crystallized from ethanol in a 63% yield, mp 225–
228 ꢁC (melted); IR, cmꢀ1; 3400 (br s, NHs), 3031 (CH
aryl), 2923 (CH alkyl), 1685 (CO), 1625 (C@N). 1H
NMR (DMSO-d6, d ppm); 1.53–1.67 (m, 2H, CH2),
1.73–1.82 (m, 2H, CH2), 2.22 (t, 2H, CH2), 2.78 (t,
2H, CH2), 5.43 (s, 1H, H-C5), 7.07–7.09 (m, 2H, phe-
nyl), 7.32–7.39 (m, 3H, phenyl) and 8.60, 10.05, 11.20
(3br s, 3NH, D2O exchangeable); MS m/z 311 (M+,
100); Anal. C17H17N3OS (311.4); requires: C, 65.56; H,
5.50; N, 13.49. Found: C, 65.49; H, 5.51; N, 13.42.
3.1.1.2. 5-(4-Chlorophenyl)-2-thioxo-2,3,5,6,7,8,9,10-
octahydro-1H-pyrimido[4,5-b]-quinolin-4-one (30b). This
compound was obtained from 1b (0.01 mol), as a yellow
powder, crystallized from ethanol in a 71% yield, mp
213–215 ꢁC; IR, cmꢀ1; 3380 (br s, NHs), 3026 (CH aryl),
3.1.2.4. 5-(4-Chlorophenyl)-2-thioxo-2,3,6,7,8,9-hexa-
hydro-1H-pyrimido[4,5-b]quinolin-4-one (3b). This com-
pound was obtained from 1b (0.01 mol), as a yellow
powder, crystallized from ethanol in a 75% yield, mp
324 ꢁC; IR, cmꢀ1; 3345 (br s, NH), 3037 (CH aryl),
1
2918 (CH alkyl), 1681 (CO), 1610 (C@N). H NMR
(DMSO-d6, d, ppm); 1.51–1.60 (m, 2H, CH2), 1.63–
1.74 (m, 2H, CH2), 2.19 (t, 2H, CH2), 2.85 (t, 2H,
CH2), 5.49 (s, 1H, H-C5), 7.24 (d, 2H, phenyl,
J = 8.4 Hz), 7.49 (d, 2H, phenyl, J = 8.6 Hz), and 8.00,
10.80, 11.55 (3br s, 3NH, D2O exchangeable); MS m/z
345 (M+, 100); Anal. C17H16ClN3OS (345.8); requires:
C, 59.03; H, 4.66; N, 12.15. Found: C, 59.05; H, 4.63;
N, 12.16.
1
2920 (CH alkyl), 1687 (CO), 1608 (C@N). H NMR
(DMSO-d6, d ppm); 1.50–1.60 (m, 2H, CH2), 1.61–
1.76 (m, 2H, CH2), 2.18 (t, 2H, CH2), 2.88 (t, 2H,
CH2), 7.13 (d, 2H, phenyl, J = 8.6 Hz), 7.47 (d, 2H, phe-
nyl, J = 8.6 Hz), and 8.21, 12.22 (2br s, 2NH, D2O
exchangeable); MS m/z 345 (M+ + 2,23), 334
(M+ + 1,29), 343 (M+, 100); Anal. C17H14ClN3OS
(343.8); requires: C, 59.38; H, 4.10; N, 12.22. Found:
C, 59.41; H, 4.15; N, 12.26.
3.1.1.3. 5-(4-Methoxyphenyl)-2-thioxo-2,3,5,6,7,8,9,10-
octahydro-1H-pyrimido[4,5-b]quinolin-4-one (30c). This
compound was obtained from 1c (0.01 mol), as a yellow
powder, crystallized from ethanol in a 67% yield, mp
184–187 ꢁC (melted); IR, cmꢀ1; 3390 (br s, NHs), 3029
(CH aryl), 2934 (CH alkyl), 1682 (CO), 1620 (C@N);
1.48–1.56 (m, 2H, CH2), 1.60–1.74 (m, 2H, CH2), 2.17
(t, 2H, CH2,), 2.86 (t, 2H, CH2), 3.86 (s, 3H, OCH3),
5.45 (s, 1H, H-C5), 7.25 (d, 2H, phenyl, J = 8.5 Hz),
7.58 (d, 2H, phenyl, J = 8.4 Hz), and 8.20, 11.30, 12.00
(3br s, 3NH, D2O exchangeable); MS m/z 341 (M+,
100); Anal. C18H19N3O2S (341.4); requires: C, 63.32;
H, 5.61; N, 12.31. Found: C, 63.29; H, 5.59; N, 12.27.
3.1.2.5.
5-(4-Methoxyphenyl)-2-thioxo-2,3,6,7,8,9-
hexahydro-1H-pyrimido[4,5-b]quinolin-4-one (3c). This
compound was obtained from 1c (0.01 mol), as a pale
yellow powder, crystallized from ethanol/dioxane (2:1)
in a 75% yield, mp 320 ꢁC (melted); IR, cmꢀ1; 3400 (br
s, NH), 3019 (CH aryl), 2921 (CH alkyl), 1683 (CO),
1
1603(C@N); H NMR (DMSO-d6, d ppm); 1.52–1.61
(m, 2H, CH2), 1.63–1.79 (m, 2H, CH2), 2.23 (t, 2H,
CH2), 2.91 (t, 2H, CH2), 3.89 (s, 3H, OCH3), 7.23 (d,
2H, phenyl, J = 8.4 Hz), 7.50 (d, 2H, phenyl,
J = 8.5 Hz), and 8.10, 11.30 (2br s, 2NH, D2O exchange-
able); MS m/z 339 (M+, 100); Anal. C18H17N3O2S
(339.4); requires: C, 63.89; H, 5.05; N, 12.38. Found:
C, 63.92; H, 5.10; N, 12.39.
3.1.2. 5-Aryl-2-thioxo-2,3,6,7,8,9-hexahydro-1H-pyrimi-
do[4,5-b]quinolin-4-ones (3a–c): General procedure
3.1.2.1. Method A. A mixture of compound 1
(0.01 mol) and 6-aminothiouracil (2) (0.01 mol) was re-
fluxed in 50 mL dimethylformamide for 20–30 h (under
TLC control). The reaction mixture was cooled; the
deposited precipitate was filtered off, washed with etha-
nol and dried, and crystallized from the appropriate sol-
vent to produce 3a–c in good yield.
3.1.3. 5-Phenyl-2-Methylthio-2,3,6,7,8,9-hexahydro-1H-
pyrimido[4,5-b]quinolin-4-one (4). To a warm ethanolic
potassium hydroxide solution (prepared by dissolving
0.01 mol of potassium hydroxide in 30 mL absolute etha-
nol) was added compound 3a (0.01 mol), the heating was
continued for 30 min, the mixture was allowed to cool to
room temperature and methyl-iodide (0.12 mol) was
added. The mixture was stirred under reflux for 3 h,
cooled to room temperature, and poured onto cold water
(100 mL). The solid precipitated was filtered off, washed
with water and dried. The compound was obtained as
yellow crystals, crystallized from ethanol in an 87% yield,
3.1.2.2. Method B. A mixture of benzaldehyde
(0.01 mol), cyclohexanone (0.01 mol), and 6-aminothio-
uracil (2) (0.01 mol) was refluxed in 50 mL dimethyl-
formamide, over 50 h (under TLC control). The
reaction mixture was cooled; the precipitate was filtered

3268
A. -R. B. A. El-Gazzar et al. / Bioorg. Med. Chem. 16 (2008) 3261–3273
mp 250 ꢁC (melted); IR, cmꢀ1; 3354 (br s, NH), 3039 (CH
aryl), 2918 (CH alkyl), 1687 (CO), 1629 (C@N); 1H
NMR (DMSO-d6, d ppm); 1.50–1.60 (m, 2H, CH2),
1.61–1.76 (m, 2H, CH2), 2.18 (t, 2H, CH2), 2.52 (s, 3H,
S-CH3), 2.88 (t, 2H, CH2), 7.11–7.14 (m, 2H, phenyl),
7.39–7.46 (m, 3H, phenyl) and 9.45 (br s, NH, D2O
exchangeable); MS m/z 323 (M+, 100); Anal.
C18H17N3OS (323.4); requires: C, 66.85; H, 5.30; N,
12.99. Found: C, 66.89; H, 5.36; N, 13.02.
chlorophenyl)-propane hydrazonoyl chloride 6b
(0.01 mol), as a brown powder, crystallized from ben-
zene in a 65% yield, mp 330 ꢁC (melted); IR, cmꢀ1
;
3032 (CH aryl), 2923 (CH alkyl), 1682 (CO), 1580
(C@N), 1556 (C@C); 1H NMR (DMSO-d6, d ppm);
1.69–1.74 (m, 2H, CH2), 1.83–1.88 (m, 2H, CH2),
2.31–2.37 (t, 2H, CH2), 2.63 (s, 3H, CH3), 3.11–3.17 (t,
2H, CH2), 7.10–7.19 (m, 2H, phenyl), 7.26–7.37 (m,
3H, phenyl), 7.46 (d, 2H, phenyl, J = 8.4 Hz), 7.71 (d,
2H, phenyl, J = 8.4 Hz); MS m/z 471 (M+ + 2,26), 470
(M+ + 1,27), 469 (M+, 100); Anal. C26H20ClN5O2
(469.9); requires: C, 66.45; H, 4.29; N, 14.90. Found:
C, 66.48; H, 4.31; N, 14.87.
3.1.4. 2-Hydrazino-5-phenyl-2,3,6,7,8,9-hexahydro-1H-
pyrimido[4,5-b]quinolin-4-one (5). A suspension of com-
pound 3a/or 4 (0.01 mol) in hydrazine hydrate (99–
100%) (25 mL) was stirred under gentle reflux. The insol-
uble solid went into solution within 10 min with copious
evolution of methyl-mercaptan to form a clear solution.
After 30 min heating was continued for 8 h and the reac-
tion mixture was allowed to cool to room temperature.
The solid which separated was filtered, washed with eth-
anol, and dried to produce 5, as a yellow powder, crystal-
lized from DMF in an 80% yield, mp 290 ꢁC (melted);
IR, cmꢀ1; 3443 (br s, NH), 3034 (CH aryl), 2905 (CH al-
3.1.5.3. 3-Acetyl-1-(4-nitroxyphenyl)-6-phenyl-7,8,9,
10-tetrahydro-triazolo[40,30:1,2]-pyrimido[4,5-b]quinolin-
5-one (7c). It was obtained from 3a (0.01 mol) and 2-
oxo-N-(4-nitrophenyl)-propane hydrazonoyl chloride
6c (0.01 mol), as a brown powder, crystallized from ben-
zene in a 68% yield, mp 270 ꢁC (melted); IR, cmꢀ1; 3040
(CH aryl), 2918 (CH alkyl), 1687 (CO), 1600 (C@N),
1
1587 (C@C); H NMR (DMSO-d6, d ppm); 1.70–1.76
1
kyl), 1689 (CO), 1635 (C@N). H NMR (DMSO-d6, d
(m, 2H, CH2), 1.85–1.91 (m, 2H, CH2), 2.33–2.38 (t,
2H, CH2), 2.66 (s, 3H, CH3), 3.14–3.19 (t, 2H, CH2),
7.08–7.16 (m, 2H, phenyl), 7.22–7.35 (m, 3H, phenyl),
7.43 (d, 2H, phenyl, J = 8.3 Hz), 7.73 (d, 2H, phenyl,
J = 8.5 Hz); MS m/z 480 (M+, 78); Anal. C26H20N6O4
(480.5); requires: C, 64.99; H, 4.19; N, 17.49. Found:
C, 65.95; H, 4.23; N, 17.52.
ppm); 1.57–1.61 (m, 2H, CH2), 1.64–1.73 (m, 2H,
CH2), 2.30 (t, 2H, CH2), 2.90 (t, 2H, CH2), 5.15 (br s,
NH2, D2O exchangeable), 7.07–7.09 (m, 2H, phenyl),
7.32–7.39 (m, 3H, phenyl) and 8.10 (2br s, 2NH, D2O
exchangeable). 13C NMR; 21.98, 26.38, 33.07, 39.06
(4C, 4CH2), 107.6, 127.0, 127.2, 127.3, 127.9, 129.8,
137.4, 149.8, 151.5, 158.5 (10C, sp2 carbon atoms with
two asymmetric) and 161.7 (CO); MS m/z 307 (M+,
100); Anal. C17H17N5O (307.3); Requires: C, 66.43; H,
5.58; N, 22.79. Found: C, 66.50; H, 5.60; N, 22.65.
3.1.5.4. 3-Ethyl-(1,6-diphenyl-7,8,9,10-tetrahydro-
triazolo[40,30:1,2]pyrimido-[4,5-b]-quinolin-5-one)acetate
(7d). It was obtained from 3a (0.01 mol) and chloro-
(phenylhydrazono)-ethylacetate 6d (0.01 mol), as a
white powder, crystallized from benzene in a 66% yield,
mp 270 ꢁC (melted); IR, cmꢀ1; 3039 (CH aryl), 2913
(CH aliphatic), 1689 (CO), 1588 (C@N), 1553 (C@C);
1H NMR (DMSO-d6, d ppm); 1.34 (t, 3H, CH3,
J = 7.0 Hz), 1.73–1.76 (m, 2H, CH2), 1.85–1.88 (m,
2H, CH2), 2.31–2.36 (t, 2H, CH2), d 3.15–3.18 (t, 2H,
CH2), 4.02 (q, 2H, CH2, J = 7.0 Hz), 7.15–7.29 (m,
2H, phenyl), 7.34–7.56 (m, 4H, phenyl), 7.67–7.72 (m,
2H, phenyl), 8.21–8.30 (m, 2H, phenyl); Anal.
C27H23N5O3 (465.4); requires: C, 69.67; H, 4.98; N,
15.05. Found: C, 69.80; H, 4.89; N, 15.08.
3.1.5. 6-Phenyl-7,8,9,10-tetrahydro-1,3-substituted-triaz-
olo[40,30:1,2]pyrimido[4,5-b]-quinolin-5-one (7a–e): Gen-
eral procedure. A mixture of compound 3a (0.01 mol),
the appropriate hydrazonoyl chloride (6a–e) (0.01 mol)
was stirred under reflux in dry chloroform (30 mL) in
the presence of four drops of triethylamine for 5 h.
The solvent was evaporated under reduced pressure.
The solid produced was washed three times by 30 mL
methanol and crystallized from the appropriate solvent
to produce (7a–e) in high yields.
3.1.5.1.
1,3,6-Triphenyl-7,8,9,10-tetrahydro-triazol-
o[40,30:1,2]pyrimido[4,5-b]quinol-in-5-one (7a). It was ob-
tained from 3a (0.01 mol) and N-phenylbenzene-carbo-
hydrazonoyl chloride 6a (0.01 mol), as white needles,
crystallized from benzene in a 65% yield, 320 ꢁC
(melted); IR, cmꢀ1; 3046 (CH aryl), 2920 (CH alkyl),
1687 (CO), 1611 (C@N), 1596 (C@C). 1H NMR
(DMSO-d6, d ppm); 1.72–1.74 (m, 2H, CH2), 1.87–1.89
(m, 2H, CH2), 2.33–2.38 (t, 2H, CH2), 3.13–3.18 (t,
2H, CH2), 7.10–7.25 (m, 2H, phenyl), 7.32–7.54 (m,
9H, phenyl), 7.65–7.68 (m, 2H, phenyl), 8.38–8.41 (m,
2H, phenyl); MS m/z 469 (M+, 100); Anal. C30H23N5O
(469.5); requires: C, 76.74; H, 4.94; N, 14.92. Found:
C, 76.70; H, 4.96; N, 14.88.
3.1.5.5. 3-Ethyl-[1-(4-tolyl)-6-phenyl-7,8,9,10-tetrahy-
drotriazolo[40,30:1,2]pyrimido-[4,5-b]quinolin-5-one]acetate
(7e). It was obtained from 3a (0.01 mol) and chloro-(4-
tolylhydrazono)-ethylacetate 6e (0.01 mol), as a brown
powder, crystallized from benzene in a 63% yield, mp
280 ꢁC (melted); IR, cmꢀ1; 3029 (CH aryl), 2923 (CH
aliphatic), 1685 (CO), 1596 (C@N), 1543 (C@C); 1H
NMR (DMSO-d6, d ppm); 1.30 (t, 3H, CH3, J = 7.2
Hz), 1.69–1.75 (m, 2H, CH2), 1.83–1.89 (m, 2H, CH2),
2.30–2.38 (t, 2H, CH2), 2.40 (s, 3H, CH3), d 3.17–3.20
(t, 2H, CH2), 4.03 (q, 2H, CH2, J = 7.1 Hz), 7.15–7.29
(m, 2H, phenyl), 7.34 (d, 2H, phenyl, J = 8.4 Hz),
7.40–7.45 (m, 3H, phenyl), 7.75 (d, 2H, phenyl,
J = 8.5 Hz), MS m/z 479 (M+, 100); Anal.
C28H25N5O3 (479.5); requires: C, 70.13; H, 5.25; N,
14.60. Found: C, 70.21; H, 5.29; N, 14.54.
3.1.5.2. 3-Acetyl-1-(4-chlorophenyl)-6-phenyl-7,8,9,10-
tetrahydrotriazolo[40,30:1,2]-pyrimido[4,5-b]quinolin-5-one
(7b). It was obtained from 3a (0.01 mol) and 2-oxo-N-(4-

A. -R. B. A. El-Gazzar et al. / Bioorg. Med. Chem. 16 (2008) 3261–3273
3269
3.1.6. 2-Acetylhydrazido-2,3,6,7,8,9-hexahydro-1H-pyrim-
ido[4,5-b]quinolin-4-one (8). A solution of compound 5
(0.01 mol) in glacial acetic acid was refluxed for 3 h.
The reaction mixture was allowed to cool to room tem-
perature, poured into cold water (100 mL), the solid so-
formed was collected by filtration, dried and crystallized
from ethanol (dark yellow powder) in a 75% yield, mp
230–232 ꢁC (melted); IR, cmꢀ1; 3389, 3100 (br s,
2NH), 2922 (CH alkyl), 1709 (CO), 1686 (CO), 1612
(C@N). The 1H NMR (DMSO-d6, d ppm) 1.74–1.76
(m, 2H, CH2), 1.90–1.95 (m, 2H, CH2), 2.37–2.39 (t,
2H, CH2), 3.00 (s, 1H, CH3), 3.07–3.08 (t, 2H, CH2),
7.06–7.30 (m, 3H, phenyl), 7.32–7.41 (m, 2H, phenyl),
8.94, 9.05, 10.98 (3br s, 3NH, D2O exchangeable); MS
m/z 349 (M+, 100), 334 (M+–CH3, 56). Anal.
C19H19N5O2 (349.4); requires: C, 65.30; H, 5.48; N,
20.04. Found: C, 65.26; H, 5.51; N, 20.11.
from ethanol/dioxane (2:1) as a yellow powder in a 68%
yield, mp 223–225 ꢁC (melted); IR, cmꢀ1; 3412 (NH)
and 1678 (CO). 1H NMR (DMSO-d6, d ppm) 1.68–
1.73 (m, 2H, CH2), 1.80–1.89 (m, 2H, CH2), 2.37–2.39
(t, 2H, CH2), 2.99–3.06 (t, 2H, CH2), 7.06–7.08 (m,
2H, phenyl), 7.30 (br s, NH2, D2O exchangeable),
7.44–7.45 (m, 3H, phenyl), 8.45 (br s, NH, D2O
exchangeable); MS m/z 332 (M+, 82); Anal.
C18H16N6O (332.4); requires: C, 65.04; H, 4.85; N,
25.29. Found: C, 65.11; H, 4.90; N, 25.35.
3.1.10. 5-Aryl-2-arylmethylenehydrazone-6,7,8,9-tetrahy-
dro-1H-pyrimido[4,5-b]-quinolin-4-one (11a–c): General
procedure. A mixture of 5 (0.01 mol), the appropriate
aromatic aldehyde (0.01 mol), and anhydrous sodium
acetate (0.02 mol) was stirred under reflux in glacial ace-
tic acid (30 mL) for 30 min. The reaction mixture was al-
lowed to cool to room temperature, whereby the formed
solid was filtered off and crystallized from appropriate
solvent to produce 11a–c in high yield.
3.1.7. 6-Phenyl-7,8,9,10-tetrahydro[1,2,4]triazolo[40,30:1,2]
pyrimido[4,5-b]quinolin-5-one (9a).
A mixture of 5
(0.01 mol), formic acid (10 mL), and 2 mL of concen-
trated hydrochloric acid was heated under reflux for
6 h. The reaction mixture was allowed to cool to room
temperature and poured onto water (100 mL). The
formed solid was collected by filtration, washed with
ethanol (20 mL), dried, and crystallized from ethanol,
orange powder, in a 67% yield, mp 212–214 ꢁC (melted);
IR, cmꢀ1; 3350 (br s, NH), 2980 (CH alkyl), 1685 (CO),
1580 (C@N), 1500 (C@C). 1H NMR (DMSO-d6, d
ppm); 1.64–1.69 (m, 2H, CH2), 1.82–1.87 (m, 2H,
CH2), 2.18–2.24 (t, 2H, CH2), 2.94–2.99 (t, 2H, CH2),
7.09–7.15 (m, 2H, phenyl), 7.33–7.40 (m, 3H, phenyl),
8.10 (s, 1H, azomethine proton), and 9.45 (br s, NH,
D2O exchangeable); MS m/z 317 (M+, 80); Anal.
C18H15N5O (317.3); requires: C, 68.12; H, 4.76; N,
22.07. Found: C, 68.11; H, 4.73; N, 22.03.
3.1.10.1. 5-Phenyl-2-phenylmethylenehydrazone-6,7,8,9-
tetrahydro-1H-pyrimido[4,5-b]quino-lin-4-one (11a). It was
obtained from compound 5 (0.01 mol) and benzalde-
hyde (0.01 mol) as pale yellow crystals, crystallized from
acetic acid in an 85% yield, mp 308–310 ꢁC (melted);
IR, cmꢀ1; 3250 (br s, NH), 3040 (CH aryl), 2920 (CH al-
1
kyl), 1670 (CO), 1600 (C@N), 1500 (C@C), H NMR
(DMSO-d6, d ppm) 1.69–1.72 (m, 2H, CH2), 1.83–1.90
(m, 2H, CH2), 2.30–2.31 (t, 2H, CH2), 2.99–3.01 (t,
2H, CH2), 7.12–7.24 (m, 2H, phenyl), 7.37–7.43 (m,
8H, phenyl) and 7.60, 10.85 (2br s, 2NH, D2O exchange-
able), 8.30 (s, 1H, azomethine proton); MS m/z 395 (M+,
76); Anal. C24H21N5O (395.4); requires: C, 72.89.63; H,
5.35; N, 17.71. Found: C, 72.86; H, 5.40; N, 17.75.
3.1.10.2. 2-(4-Chlorophenylmethylenehydrazone-5-phe-
nyl-6,7,8,9-tetrahydro-1H-pyrimido[4,5-b]quinolin-4-one
(11b). It was obtained from compound 5 (0.01 mol) and
4-chlorobenzaldehyde (0.01 mol) as pale yellow crystals,
crystallized from acetic acid in an 83% yield, mp 320–
322 ꢁC (melted); IR, cmꢀ1; 3368 (br s, NH), 3044 (CH
aryl), 2916 (CH alkyl), 1676 (CO), 1605 (C@N), 1517
(C@C), 1H NMR (DMSO-d6, d ppm) 1.61–1.62 (m,
2H, CH2), 1.77–1.90 (m, 2H, CH2), 2.18 (t, 2H, CH2),
2.86–2.90 (t, 2H, CH2), 7.08–7.09 (m, 2H, phenyl),
7.39–7.43 (m, 3H, phenyl, J = 8.4 Hz), 7.89–7.92 (d,
2H, phenyl, J = 8.5 Hz), 8.03–8.05 (d, 2H, phenyl)
8.12 (s, 1H, azomethine proton) and 10.83, 11.64 (br s,
2NH, D2O exchangeable); MS m/z 431 (M+ + 2, 19),
430 (M+ + 1,27), 429 (M+, 89); Anal. C24H20ClN5O
(429.9); requires: C, 67.05; H, 4.69; N, 16.29. Found:
C, 67.11; H, 4.72; N, 16.34.
3.1.8. 3-Methyl-6-phenyl-7,8,9,10-tetrahydro[1,2,4]triaz-
olo[40,30:1,2]pyrimido[4,5-b]-quinolin-5-one (9b). A mix-
ture of 5 (0.01 mol) and glacial acetic acid (30 mL)
was stirred under reflux for 6 h (TLC). The reaction
mixture was allowed to cool to room temperature and
then poured onto water (100 mL). The solid formed
was collected by filtration, washed with ethanol
(20 mL), dried, and crystallized from ethanol, orange
powder, in a 67% yield, mp 310–313 ꢁC (melted);
IR, cmꢀ1; 3316 (br s, NH), 2986 (CH alkyl), 1678
(CO), 1583 (C@N), 1507 (C@C). 1H NMR (DMSO-
d6, d ppm) 1.63–1.67 (m, 2H, CH2), 1.80–1.86 (m, 2H,
CH2), 2.19–2.23 (t, 2H, CH2), 2.95–3.00 (t, 2H, CH2),
3.25 (s, 3H, CH3), 7.05–7.13 (m, 2H, phenyl), 7.35–
7.41 (m, 3H, phenyl) and 9.05 (br s, NH, D2O exchange-
able); MS m/z 331 (M+, 100); Anal. C19H17N5O
(331.37); requires: C, 68.86; H, 5.17; N, 21.14. Found:
C, 68.83; H, 5.12; N, 21.09.
3.1.10.3. 2-(4-Methoxyphenylmethylenehydrazone-5-
phenyl-6,7,8,9-tetrahydro-1H-pyrimido[4,5-b]quinolin-4-
one (11c). It was obtained from compound 5 (0.01 mol)
and 4-methoxybenzaldehyde (10 m mol) as a yellow
powder, crystallized from acetic acid in an 81% yield,
mp 306–308 ꢁC (melted); IR, cmꢀ1; 3368 (br s, NH),
3044 (CH aryl), 2916 (CH alkyl), 1676 (CO), 1605
(C@N), 1517 (C@C), 1H NMR (DMSO-d6, d ppm)
1.67–1.68 (m, 2H, CH2), 1.83–1.89 (m, 2H, CH2),
3.1.9. 3-Amino-6-phenyl-7,8,9,10-tetrahydro[1,2,4]triaz-
olo[40,30:1,2]pyrimido[4,5-b]-quinolin-5-one (10). A mix-
ture of
5 (0.01 mol) and potassium thiocyanate
(0.15 mol) was heated under reflux in acetic acid for
6 h. The reaction mixture was allowed to cool to room
temperature and poured onto water. The precipitate
formed was collected by filtration, dried and crystallized

3270
A. -R. B. A. El-Gazzar et al. / Bioorg. Med. Chem. 16 (2008) 3261–3273
2.28–2.29 (t, 2H, CH2), 2.96–2.98 (t, 2H, CH2), 3.72 (s,
3H, OCH3), 7.09–7.10 (m, 2H, phenyl), 7.10–7.24 (d,
2H, phenyl, J = 8.6 Hz), 7.40–7.42 (m, 3H, phenyl),
7.52–7.61 (d, 2H, phenyl, J = 8.6 Hz), 7.65 (s, 1H, azo-
methine proton) and 8.25, 11.28 (br s, 2NH, D2O
exchangeable); Anal. C25H23N5O2 (425.5); Requires: C,
70.57; H, 5.45; N, 16.46. Found: C, 70.52; H, 5.47; N,
16.50.
and 9.45 (br s, NH, D2O exchangeable); MS m/z 318
(M+, 95); Anal. C17H14N6O (318.3); requires: C, 64.47;
H, 4.43; N, 26.41. Found: C, 64.09; H, 4.41; N, 26.39.
3.1.13. 2-Amino-5-phenyl-6,7,8,9-tetrahydro-pyrimido [4,5-
b]quinolin-4-one (14). To a well-stirred solution of the
appropriate tetrazolothienopyrimidine 13 (0.01 mol)
in glacial acetic acid (30 mL) was added portionwise
activated zinc dust (5.00 g) at room temperature over
a period of 30 min. Stirring was continued for addi-
tional 3 h. Thereafter the reaction mixture was heated
on a water bath (80–90 ꢁC) for 3 h. The progress of
reduction was monitored by TLC. After allowing the
reaction mixture to cool to room temperature, it was
poured onto cold water (100 mL). The insoluble solid
which separated was filtered, washed with water, and
dried. The crude solid was extracted with hot diethyl
ether and the solid obtained after the removal of ether
under reduced pressure was crystallized from ethanol in
a 45% yield, mp 220–222 ꢁC (melted); IR, cmꢀ1; 3310
(br s, NH2), 2910 (CH alkyl), 1687 (CO), 1589
(C@N), 1551 (C@C); 1H NMR (DMSO-d6, d ppm)
1.73–1.75 (m, 2H, CH2), 1.89–1.95 (m, 2H, CH2),
2.37–2.45 (t, 2H, CH2), 3.11–3.22 (t, 2H, CH2), 7.08–
7.14 (m, 2H, phenyl), 7.43–7.48 (m, 3H, phenyl), and
11.48 (br s, NH, D2O exchangeable); MS m/z 292
(M+, 74); Anal. C17H16N4O (292.3); requires: C,
69.84; H, 5.52; N, 19.16. Found: C, 69.80; H, 5.49;
N, 19.09.
3.1.11. 7-Phenyl-3-(methyl/or phenyl)-8,9,10,11-tetrahy-
dro[1,3]pyrazolo[30,20:1,2]-pyrimido[4,5-b]quinolin-6-one
(12a and 12b): General procedure. A mixture of com-
pound 5 (0.01 mol) and chloroacetone or phenacylbro-
mide (0.01 mol) was heated under reflux for 5 h in
30 mL of dry xylene. The solid that separated upon
cooling was filtered off and crystallized from appropriate
solvent to produce 13a and 13b in high yield.
3.1.11.1. 7-Phenyl-3-methyl-8,9,10,11-tetrahydro[1,3]
pyrazolo[30,20:1,2]pyrimido[4,5-b]quinolin-6-one (12a). It
was obtained from compound 5 (0.01 mol) and chloro-
acetone (0.01 mol); as white crystals, crystallized from
ethanol in a 58% yield, mp 350–353 ꢁC (dec); IR, cmꢀ1
;
3420 (br s, NH), 2950 (CH alkyl), 1687 (CO), 1600
(C@N), 1543 (C@C); 1H NMR (DMSO-d6, d ppm);
1.63–1.69 (m, 2H, CH2), 1.80–1.85 (m, 2H, CH2),
2.21–2.26 (t, 2H, CH2), 2.97–2.99 (t, 2H, CH2), 3.23 (s,
3H, CH3), 5.62 (br s, NH2, D2O exchangeable), 7.06–
7.08 (m, 2H, phenyl), 7.35–7.45 (m, 3H, phenyl), 8.10
(s, 1H, pyrazolyl proton); Anal. C20H19N5O (345.4); re-
quires: C, 69.54; H, 5.54; N, 20.28. Found: C, 69.49; H,
5.58; N, 20.31.
3.1.14. 2-(3-Amino-5-hydroxy-4H-pyrazol-5-one-1-yl)-5-
phenyl-6,7,8,9-tetrahydro-pyrimido[4,5-b]quinolin-4-one
(15). To a warm ethanolic sodium ethoxide solution
(prepared by dissolving (0.01 mol) sodium metal in
absolute ethanol (30 mL)) were added compound 5
(0.01 mol) and ethyl-cyanoacetate (0.01 mol). The mix-
ture was stirred under reflux for 8 h, the reaction mix-
ture was allowed to cool to room temperature, then
poured onto cold water (100 mL), neutralized with ace-
tic acid. The solid product precipitated was filtered off,
washed with water, ethanol, dried, and crystallized from
ethanol, pale yellow powder, in a 72% yield, mp330 ꢁC
(dec.); IR, cmꢀ1; 3318 (br s, NH), 2921 (CH alkyl),
1687 (CO), 1601 (C@N), 1520 (C@C); 1H NMR
(DMSO-d6, d ppm) 1.52–1.54 (m, 2H, CH2), 1.66–1.69
(m, 2H, CH2), 2.10 (t, 2H, CH2), 2.78–2.80 (t, 2H,
CH2), 3.55 (br s, 1H, OH coupled with H2O of DMSO),
5.10 (br s, NH2, D2O exchangeable), 6.02 (s, 1H, pyraz-
olyl proton), 6.96–6.99 (m, 2H of phenyl), 7.31–7.36 (m,
3H, phenyl) and 9.10 (br s, NH, D2O exchangeable); MS
m/z 374 (M+, 100); Anal. C20H18N6O2 (374.4); requires:
C, 64.16; H, 4.84; N, 22.45. Found: C, 64.19; H, 4.90; N,
22.42.
3.1.11.2. 3,7-Diphenyl-3-phenyl-8,9,10,11-tetrahydro[1,3]
pyrazolo[30,20:1,2]pyrimi-do[4,5-b]quinolin-6-one (12b). It
was obtained from compound 5 (0.01 mol) and phen-
acylbromide (0.01 mol), as a yellow powder, crystallized
from ethanol in a 55% yield, mp 297–300 ꢁC (melted);
IR, cmꢀ1; 3279 (br s, NH), 3039 (CH aryl), 2916 (CH al-
1
kyl), 1686 (CO), 1647 (C@N), 1600 (C@C), H NMR
(DMSO-d6, d ppm) 1.65–1.69 (m, 2H, CH2), 1.81–1.87
(m, 2H, CH2), 2.21–2.25 (t, 2H, CH2), 2.96–3.02 (t,
2H, CH2), 7.06–7.08 (m, 2H, phenyl), 7.35–7.56 (m,
8H, phenyl), 8.13 (s, 1H, pyrazolyl proton), 11.30 (br
s, NH2, D2O exchangeable); MS m/z 407 (M+, 100);
Anal. C25H21N5O (407.5); requires: C, 73.69; H, 5.19;
N, 17.19. Found: C, 73.65; H, 5.14; N, 17.15.
3.1.12. 6-Phenyl-7,8,9,10-tetrahydrotetraazolo[40,30:1,2]
pyrimido[4,5-b]quinolin-5-one (13). To an ice-cold solu-
tion of compound 5 (0.01 mol) in acetic acid (10 mL)
was added dropwise a solution of sodium nitrite
(0.15 mol) in a least amount of water in an ice bath at
ꢀ5 ꢁC. The reaction mixture was allowed to stand over-
night at room temperature, then poured onto water
(100 mL). The solid precipitated was filtered off and
crystallized from ethanol to produce 13 as yellow pow-
3.1.15. 2-(3-Methyl-5-substituted-methyl-4-(un)substituted-
pyrazol-1-yl)-5-phenyl-6,7,8,9-tetrahydropyrimido[4,5-b]
quinolin-4-one (16a and 16b): General procedure. A mix-
ture of compound 5 (0.01 mol) and the b-diketone
(0.01 mol) in absolute ethanol (30 mL) was stirred under
reflux for 5 h. The reaction mixture was allowed to cool
to 0 ꢁC for 3 h, the deposited precipitate was filtered off,
dried, and crystallized from an appropriate solvent to
produce 16a and 16b in high yields.
der in a 50% yield, mp 330–332 ꢁC (dec); IR, cmꢀ1
;
3243 (br s, NH), 2934 (CH alkyl), 1700 (CO), 1629
1
(N@N), 1582 (C@N), 1506 (C@C); H NMR (DMSO-
d6, d ppm) 1.73–1.75 (m, 2H, CH2), 1.89–1.95 (m, 2H,
CH2), 2.37–2.45 (t, 2H, CH2), 3.11–3.22 (t, 2H, CH2),
7.08–7.14 (m, 2H, phenyl), 7.43–7.48 (m, 3H, phenyl),

A. -R. B. A. El-Gazzar et al. / Bioorg. Med. Chem. 16 (2008) 3261–3273
3271
3.1.15.1.
2-(3,5-Dimethyl-pyrazol-1-yl)-5-phenyl-
(s, 3H, CH3), 2.24–2.27 (t, 2H, CH2), 2.96–3.02 (t, 2H,
CH2), 3.40 (s, 2H, CH2), 4.09–4.14 (q, 2H, CH2,
J = 7.2 Hz), 7.06–7.08 (m, 2H, phenyl), 7.36–7.41 (m,
3H, phenyl), 9.80–10.55 (2br s, 2NH, D2O exchange-
able); MS m/z 419 (M+, 65); Anal. C23H25N5O3
(419.5); requires: C, 65.85; H, 6.01; N, 16.70. Found:
C, 65.83; H, 6.04; N, 16.87.
6,7,8,9-tetrahydropyrimido[4,5-b]-quinolin-4-one (16a). It
was obtained from the reaction of 5 (0.01 mol) with pen-
tan-2,4-dione (0.01 mol), as pale light crystals, crystal-
lized from ethanol in a 75% yield, mp 282–285 ꢁC
(melted); IR, cmꢀ1; 3300 (br s, NH), 3042 (CH aryl),
2937 (CH alkyl), 1694 (CO), 1629 (C@N), 1548
(C@C). 1H NMR (DMSO-d6, d ppm): 1.72–1.73 (m,
2H, CH2), 1.85–1.90 (m, 2H, CH2), 2.22 (s, 3H, CH3),
2.38–2.40 (t, 2H, CH2), 2.86 (s, 3H, CH3), 3.16–3.20 (t,
2H, CH2), 6.05 (s, 1H, pyrazolyl proton), 7.11–7.12
(m, 2H, phenyl), 7.44–7.47 (m, 3H, phenyl), 10.23 (br
s, NH, D2O exchangeable); MS m/z 371 (M+, 100);
Anal. C22H21N5O (371.4); requires: C, 71.14; H, 5.70;
N, 18.85. Found: C, 71.20; H, 5.67; N, 18.90.
3.1.18. 5-Phenyl-2-(3-methyl-4H-pyrazol-5-one-1-yl)-
6,7,8,9-tetrahydropyrimido[4,5-b]quinolin-4-one (19)
3.1.18.1. Method A. A solution of compound 5
(0.01 mol) and ethyl acetoacetate (0.01 mol) in sodium
ethoxide solution (prepared by dissolving 0.01 mol of
sodium metal in 30 mL absolute ethanol was heated un-
der reflux with stirring for 6 h. The reaction mixture was
allowed to cool and poured onto cold water (100 mL)
and neutralized by acetic acid, whereby a solid was pre-
cipitated, which was filtered off and crystallized from
ethanol to produce 19 as a yellow powder in a 62% yield,
mp 330 ꢁC (dec.).
3.1.15.2. 2-(3,5-Dimethyl-4-chloro-pyrazol-1-yl)-5-
phenyl-6,7,8,9-tetrahydropyrimi-do[4,5-b]quinolin-4-one
(16b). It was obtained from the reaction of 5 with 3-
chloropentan-2,4-dione (0.01 mol), as a light yellow
powder and crystallized from ethanol in a 72% yield,
261–263 ꢁC (melted); IR, cmꢀ1; 3286 (br s, NH), 3080
(CH aryl), 2939 (CH alkyl), 1678 (CO), 1605 (C@N),
3.1.18.2. Method B. A solution of compound 18
(0.01 mol) was heated under reflux with sodium ethoxide
solution (prepared by dissolving (0.01 mol) of sodium
metal in 30 mL absolute ethanol) for 3 h. The reaction
mixture was allowed to cool, poured onto water
100 mL, and neutralized by acetic acid; the precipitate
formed was filtered off and crystallized from ethanol in
a 68% yield: IR (KBr, cmꢀ1); 3400 (br s, NH), 2936
(CH alkyl), 1698, 1684 (2CO), 1550 (C@N), 1500
(C@C), 1H NMR (DMSO-d6, d ppm) 1.65–1.68 (m,
2H, CH2), 1.80–1.86 (m, 2H, CH2), 1.99 (s, 3H, CH3),
2.20–2.24 (t, 2H, CH2), 2.97–3.03 (t, 2H, CH2), 4.53 (s,
2H, CH2), 7.03–7.08 (m, 2H, phenyl), 7.33–7.40 (m,
3H, phenyl), 10.3 (br s, NH, D2O exchangeable); MS
m/z 373 (M+, 100); Anal. C21H19N5O2 (373.4); requires:
C, 67.54; H, 5.13; N, 18.75. Found: C, 67.60; H, 5.25; N,
18.83.
1
1543 (C@C); H NMR (DMSO-d6, d ppm) 1.64–1.70
(m, 2H, CH2), 1.75–1.80 (m, 2H, CH2), 2.25–2.27 (t,
2H, CH2), 2.30 (s, 3H, CH3), 2.48 (s, 3H, CH3), 2.98–
3.00 (t, 2H, CH2), 7.10–7.11 (m, 2H, phenyl), 7.35–
7.40 (m, 3H, phenyl), 11.82 (br s, NH, D2O exchange-
able); MS m/z 407 (M+ + 2, 33), 406 (M+ + 1,25), 405
(M+, 100); Anal. C22H20ClN5O (405.9); requires: C,
65.10; H, 4.97; N, 17.26. Found: C, 65.06; H, 4.93; N,
17.31.
3.1.16. 2-Chloroacetylhydrazido-5-phenyl-6,7,8,9-tetra-
hydro-1H-pyrimido[4,5-b]quinolin-4-one (17). A mixture
of compound 5 (0.01 mol) and chloroacetyl chloride
(0.01 mol) was gently heated on a water bath (60–
80 ꢁC) in dry dioxane (30 mL) for 6 h and the reaction
mixture was allowed to cool to room temperature. The
solid formed was filtered off, dried, and crystallized from
ethanol in a 65% yield, mp 330 ꢁC (dec.); IR, cmꢀ1; 3365
(br s, NH), 3043 (CH aryl), 2908 (CH alkyl), 1731, 1687
(2CO), 1630 (C@N); 1H NMR (DMSO-d6, d ppm):
1.64–1.65 (m, 2H, CH2), 1.80–1.82 (m, 2H, CH2), 2.23
(t, 2H, CH2), 2.98–3.00 (t, 2H, CH2), 3.25–3.28 (s, 2H,
CH2), 7.10–7.14(m, 2H, phenyl), 7.30–7.40 (m, 3H, phe-
nyl), 9.45, 1.45, 11.45 (3br s, 3NH, D2O exchangeable);
MS m/z 385 (M+ + 2, 28), 384 (M+ + 1,36), 383 (M+,
100); Anal. C19H18ClN5O2 (383.8); requires: C, 59.45;
H, 4.73; N, 18.25. Found: C, 59.43; H, 4.80; N, 18.12.
3.2. Antimicrobial screening
The bacterial isolates representing Gram (ꢀve) and
Gram (+ve) bacteria were recovered on Nutrient and
Macconky agar. The two fungal isolates Candida albi-
cans and Candida glabrate were isolated on Sabourauds
dextrose agar (Oxoid). They are isolated from clinical
samples and identified to the species level according to
different API systems (Biomerilux). The selected com-
pounds were tested in vitro using the agar disk diffusion
method23,24 taking Nalidixic acid and Nystatin as refer-
ence drugs for bacteria and fungi, respectively. The anti-
microbial potentialities of the tested compounds were
estimated by placing pre-sterilized filter paper disks
(5 mm in diameter) impregnated with 50 lg/disk using
dimethylsulfoxide (DMSO) as solvent which showed
no inhibition zones. The inhibition zones of the tested
compounds were measured after 24–28 h incubation at
37 ꢁC for bacteria and at 28 ꢁC after 5 days for fungi.
The minimal inhibitory concentration (MIC) determina-
tion method of the biologically active compounds (Table
2) was applied using different concentrations per disk
against G (ꢀve) and G (+ve) bacteria, and fungi. Refer-
ence Nystatin and Nalidixic acid disks were supplied by
3.1.17. 2-(Ethyl-5-phenyl-6,7,8,9-tetrahydropyrimido[4,5-
b]-quinolin-4-one)acetate-hydrazone (18). A mixture of
compound
5
(0.01 mol) and ethyl acetoacetate
(0.01 mol) was refluxed in absolute ethanol (30 mL)
for 5 h. The reaction mixture was allowed to cool to
room temperature and the solid precipitate produced
was filtered off and crystallized from ethanol, a pale
brown powder, in a 58% yield, mp 245 ꢁC (melted);
IR, cmꢀ1; 3250 (br s, NH), 2942 (CH alkyl), 1740,
1680 (2CO), 1580 (C@N), 1500 (C@C), 1H NMR
(DMSO-d6, d ppm) 1.22–1.29 (t, 3H, CH3, J = 7.2 Hz),
1.63–1.68 (m, 2H, CH2), 1.78–1.84 (m, 2H, CH2), 2.03

3272
A. -R. B. A. El-Gazzar et al. / Bioorg. Med. Chem. 16 (2008) 3261–3273
Pasteur laboratory in Egypt of concentration 100 U and
30 lg, respectively.
of groups II to XI at doses of 15 mg/kg. Mice of group
VI (reference) were orally treated with acetyl salicylic
acid at a dose of 100 mg/kg. The reaction time was
again measured at 15 min and repeated at 30, 60, and
90 min after treatment. To avoid tissue damage to
the mice paws, cut-off time for the response to the
thermal stimulus was set at 60 s. The reaction time
was calculated for each synthesized compound and
drug-treated group.
3.3. Animals
Both sex of Swiss mice weighing 25–30 g used in analge-
sic activity and adulte male of Sprague-Dawley rats
weighing between 150 and 180 g were used in anti-
inflammatory activity, taking into account international
principle and local regulations concerning the care and
use of laboratory animals.25 The animals had free access
to standard commercial diet and water ad libitum and
were kept in rooms maintained at 22 1 ꢁC with 12 h
light dark cycle.
3.5.2. Writhing test. An acetic acid-induced abdominal
constriction in mice (Writhing effect) was determined
by the method described by Collier et al.22 Seventy-
two mice were divided into 12 equal groups and
pre-treated as follows: Group I which served as a con-
trol orally received 10% v/v Tween 80 in distilled
water. Groups II to XI received the aqueous suspen-
sion of synthesized compounds in 10% v/v Tween 80
in distilled water orally at dose 15 mg/kg. Group VI
was orally received acetyl salicylic acid at a dose of
100 mg/kg. After 30 min, each mouse was adminis-
tered 0.7% of an aqueous solution of acetic acid
(10 ml/kg) intraperitoneally and the mice were then
placed in transparent boxes for observation. The num-
ber of writhes was counted for 20 min after acetic acid
injection. The number of writhes in each treated group
was compared to that of a control un-treated group.
The number of writhing and stretching was recorded
and the percentage protection was calculated using
the following ratio: (Control mean ꢀ Treated mean/
Control mean) · 100.
3.4. Anti-inflammatory effect
The anti-inflammatory testing was performed according
to the method of Winter et al.26 For this purpose, 36 rats
weighing 150–180 g were used. Edema was induced in
the left hand paw of all rats by subcutaneous (sc) injec-
tion of 0.1 ml of 1% (w/v) carrageenin in distilled water
into their footpads. Rats were divided into six groups of
six mice each. The 1st group was kept as control and was
given the respective volume of the solvent (10% v/v of
Tween 80 in distilled water). The 2nd to 5rd groups were
orally administered aqueous suspension of synthesized
compounds at a dose of 15 mg/kg 1 h before carrageenin
injection. The last group was administered indometha-
cin (Indocidꢂ) in a dose of 10 mg/kg orally as a standard
reference.27 The paw volume of each rat was measured
using Plethysmometer; before carrageenin injection
and then hourly for 4 h post-administration of aqueous
suspension of synthesized compounds. The edema rate
and inhibition rate of each group were calculated as fol-
lows: Edema rate (E)% = Vt ꢀ Vc/Vc, and inhibition rate
(I)% = Ec ꢀ Et/Ec, where Vc is the volume before carra-
geenin injection (ml), Vt is the volume at t h after carra-
geenin injection (ml), Ec is the edema rate of control
group, Et is the edema rate of treated group).
3.6. Statistical analysis
All statistical analyses were done by SPSS version 10 by
one-way ANOVA using Dunnett’s test.
Acknowledgment
Authors thank Prof. Dr. Ahmed. S. Aly, Professor of
Organic Chemistry Photochemistry Department and
Professor Dr. El-Eraky. W Professor of pharmacology
and head of Pharmacological unit, Pharmacology
department, National Research Centre, Dokki, Cairo,
Egypt, for their help.
3.5. Analgesic effect
Experimental models used in this study were selected to
investigate both centrally and peripherally mediated
analgesic effects of the tested compounds. For this pur-
pose; the acetic acid abdominal constriction method was
used to elucidate the peripheral effect and the hot-plate
test to reveal central activity of the tested compounds.
References and notes
3.5.1. Hot-plate test. The experiment was carried out as
described by Turner21 using hot-plate apparatus, main-
tained at 53 0.5 ꢁC. Seventy-two mice were divided
into 12 groups, six animals in each group. The reaction
time of the mice to the thermal stimulus was the time
interval between placing the animal in the hot plate
and when it licked its hind paw or jumped. Reaction
time was measured prior to aqueous suspension of syn-
thesized compounds and drug treatment (0 min).
Group I was kept as normal control and received the
solvent (10% v/v Tween 80 in distilled water). The sus-
pension of synthesized compounds in 10% v/v Tween
80 in distilled water was orally administered to mice
1. El-Sayed, O. A.; Al-Bassam, B. A.; Hussein, M. E. Arch.
Pharm. 2002, 335, 403.
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