Novel quinazolinone derivatives as possible antitumor agents

Article abstract of DOI:10.1080/10426500600867042

The synthesis of a novel series of quinazolinone derivatives 6-15 having the biologically active thioxo group utilizing 2-isothiocyanato-benzoic acid methyl ester 2 is reported. Their structures have been confirmed on the basis of elemental analyses and (IR, ¹H NMR, and mass) spectral data. Preliminary testing for the in vitro antitumor activity of some synthesized compounds against Ehrlich Ascities Carcinoma cells was carried out.

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Novel Quinazolinone
Derivatives as Possible
Antitumor Agents
Saber El-Sayed Barakat a , Moustafa M. Ghorab b ,
Helmy M. Saker a & Mahmoud M. Abd Rabo a
a Department of Pharmaceutical Chemistry, Al-Azhar
University, Cairo, Egypt
b Department of Drug Radiation Research, National
Center for Radiation Research and Technology, Nasr
City, Cairo, Egypt
Version of record first published: 01 Feb 2007.
To cite this article: Saber El-Sayed Barakat, Moustafa M. Ghorab, Helmy M. Saker &
Mahmoud M. Abd Rabo (2007): Novel Quinazolinone Derivatives as Possible Antitumor
Agents, Phosphorus, Sulfur, and Silicon and the Related Elements, 182:1, 65-77
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Phosphorus, Sulfur, and Silicon, 182:65–77, 2007
Copyright © Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500600867042
Novel Quinazolinone Derivatives as Possible
Antitumor Agents
Saber El-Sayed Barakat
Department of Pharmaceutical Chemistry, Al-Azhar University,
Cairo, Egypt
Moustafa M. Ghorab
Department of Drug Radiation Research, National Center for Radiation
Research and Technology, Nasr City, Cairo, Egypt
Helmy M. Saker
Mahmoud M. Abd Rabo
Department of Pharmaceutical Chemistry, Al-Azhar University,
Cairo, Egypt
The synthesis of a novel series of quinazolinone derivatives 6–15 having the biolog-
ically active thioxo group utilizing 2-isothiocyanato-benzoic acid methyl ester 2 is
reported. Their structures have been confirmed on the basis of elemental analyses
1
and (IR, H NMR, and mass) spectral data. Preliminary testing for the in vitro anti-
tumor activity of some synthesized compounds against Ehrlich Ascities Carcinoma
cells was carried out.
Keywords Antitumor activity; quinazoline-4(3H)-one
INTRODUCTION
Quinazolines and condensed quinazolines have received much at-
tention over the years because of their interesting pharmacological
properties.1−6 In our laboratory considerable effort recently has been
invested in the synthesis and evaluation of heterocyclic compounds con-
taining the quinazoline and thienopyrimidine nucleus, leading to nu-
merous compounds with promising antitumor activity.7−12 Moreover,
the quinazoline function is quite stable13 and has inspired medicinal
Received February 28, 2006; accepted May 18, 2006.
Address correspondence to Moustafa M. Ghorab, Department of Drug Radiation
Research, National Centre for Radiation Research and Technology, P.O. Box. 29, Nasr
City, Cairo, Egypt. E-mail: ghorabmoustafa@hotmail.com
65

66
S. El-Sayed Barakat et al.
TABLE I Physical Properties and Molecular
Formula of the Synthesized Compounds
Compound No.
M.P. (◦C)
Yield % Mol. Formula (Mol-wt)
3
78
90
80
60
75
85
89
90
60
85
80
70
65
50
C11H13NO3S
(239.29)
4
40
232
238
240
222
254
250
252
220
250
>300
218
C
12H15NO4S
(269.32)
5
C14H12N2O3S
(288.32)
6
C
C
C
10H10N2O2S
(222.26)
11H12N2O2S
(236.29)
13H12N2O3S
(276.31)
7
8
9
C16H12N2O3S
(312.06)
10
11
12
13
14
15
C
15H10N2O3S
(298.32)
C16H12N2O3S
(312.06)
C
15H9BrN2O3S
(377.21)
C
11H10N2O3S
(250.27)
C
17H14N2O3S
(326.37)
C13H8ClN3OS
(289.74)
chemists to introduce this stable fragment on bioactive moieties to syn-
thesize new potential medicinal agents. In the present study the thioxo
group has been incorporated at position-2 of the quinazolinone to result
in 2-thioxo or mercaptoquinazolinone likely to have superior antitumor
properties.
MATERIALS AND METHODS
General Considerations
Elemental analyses (C, H, N) were performed on a Perkin-Elmer 2400
analyzer (Perkin-Elmer, Norwalk, CT, USA) at the micronalytical unit
of Cairo University. All compounds were within 0.4% of the theoretical
values.
Melting points (Table I) are uncorrected and were determined on
a Stuart melting point apparatus (Stuart Scientific, Redhill, UK). IR

Novel Quinazolinone Derivatives as Possible Antitumor Agents
67
spectra were measured on an Infinity gold FTIR spectrophotometer
1
(Unicam, UK). H NMR spectra were obtained on Bruker 300 MHz
NMR spectrophotometer (Bruker, Munich, Switzerland) in Deuterated
chloroform (CDCl3) as a solvent, using tetramethylsilane (TMS) as an
internal standard. Mass spectra were run on a Varian MAT 311-A 70
e.v. (Varian, Fort Collins, USA) and MS. model 5988 (Hewlett-Packard,
USA).
Synthesis
2-Ethoxythiocarbonylamino-benzoic Acid Methyl Ester (3)
A solution of 2 (0.01 mol) in absolute ethanol (10 mL) was refluxed
for 8 h. The solid obtained was recrystallized from ethanol to give 3
(Table I). IR (kBr, cm−1): 3188 (NH), 2990, 2900 (CH aliph.), 1692
(C O), 1260 (C S). δ 1.4 [t, 3H, CH3], 3.7 [s, 3H, OCH3], 4.65 [q, 2H,
CH2], 7.0–8.4 [m, 4H, Ar-H], 11.7 [s, 1H, NH].
2-(2-Methoxy-ethoxythiocarbonylamino)-benzoic Acid
Methyl Ester (4)
A solution of 2 (0.01 mol) in 2-methoxy ethanol (10 mL) was refluxed
for 8 h. The solid obtained was recrystallized from ethanol to give 4
(Table I). IR (kBr, cm−1): 3176 (NH), 2892 (CH aliph.), 1696 (C O),
1264 (C S). δ 3.5, 3.8 [2s, 6H, 2OCH3], 3.99 [t, 2H, OCH2], 4.75 [t, 2H,
OCH2], 7.1–8.5 [m, 4H, Ar-H], 11.7 [s, 1H, NH].
2-(Pyridin-3-yloxythiocarbonylamino)-benzoic Acid
Methyl Ester (5)
A mixture of 2 (0.01 mol) and 3-hydroxypyridine (0.01 mol) in dioxane
(25 mL) containing triethylamine (0.5 mL) was refluxed for 10 h. The
reaction mixture was cooled, and the solid obtained was recrystallized
from dioxane to give 5 (Table I). IR (kBr, cm−1): 3306 (NH), 1700 (C O),
1620 (C N), 1274 (C S). δ 3.7 [s, 3H, OCH3], 7.1–8.2 [m, 8H, Ar-H],
10.5 [s, 1H, NH].
3-(2-Hydroxy-ethyl)-2-thioxo-2,3-dihydro-1H-quinazolin-
4-one (6) and 3-(3-hydroxy-propyl)-2-thioxo-2,3-
dihydro-1H-quinazolin-4-one (7)
A mixture of 2 (0.01 mol) and the ethanolamine and/or propanol
amine (0.01 mol) in dioxane (25 mL) containing triethylamine (0.5 mL)
was refluxed for 8 h. The reaction mixture was cooled, and the solid
obtained was recrystallized from ethanol to give 6 and 7, respectively
(Table I). IR (kBr, cm−1) 6: 3362 (OH), 3300 (NH), 3018 (CH arom.),
2956 (CH aliph.), 1664 (C O), 1278 (C S). δ 4.1 [m, 2H, CH2OH],
4.85 [t, 2H, NCH2], 7.2–8.35 [m, 4H, Ar-H], 10.2 [hump, 1H, OH]. IR

68
S. El-Sayed Barakat et al.
(kBr, cm−1) 7: 3306 (NH, OH), 1696 (C O), 1276 (C S). δ 2.16 [t, 2H,
NCH2], 3.60–3.76 [m, 2H, CH2], 4.75 [t, 2H, OCH2], 7.1–8.2 [m, 4H,
Ar-H], 8.25, 8.3 [2s, 2H, NH + OH].
3-(4-Oxo-2-thioxo-1, 4-dihydro-2H-quinazolin-3-yl)–but-2-
enoic Acid Methyl Ester (8)
A mixture of 2 (0.01 mol) and methyl-3-aminocratonate (0.01 mol)
in dioxane (25 mL) containing triethylamine (0.5 mL) was refluxed for
9 h. The reaction mixture was cooled, and the solid obtained was recrys-
tallized from dioxane to give 8 (Table I). IR (kBr, cm−1): 3306 (NH),
2924 (CH aliph.), 1698 (C O), 1274 (C S). δ 1.5 [s, 3H, CH3], 3.7 [s,
3H, OCH3], 7.0–8.25 [m, 5H, Ar-H , CH], 10.4 [s, 1H, NH].
3-(Methylbenzoate-2-yl)-2-thioxo-2,3-dihydro-1H-
quinazolin-4-one (9)
A mixture of 2 (0.01 mol) and methylanthranilate (0.01 mol) in diox-
ane (25 mL) containing triethylamine (0.5 mL) was refluxed for 8 h. The
reaction mixture was cooled, and the solid obtained was recrystallized
from ethanol to give 9 (Table I). IR (kBr, cm−1) 3304 (NH), 1700, 1710
(2C O), 1274 (C S). MS (m/z): 312 (M+, 12.4%), 253 (100%) (Chart 1).
2-(1,2-Dihydro-4-oxo-2-thioxoquinazolin-3(4H)-yl) Benzoic
Acid (10), 2-(1,2-dihydro-4-oxo-2-thioxoquinazolin-3(4H)-yl)-5-
methyl Benzoic Acid (11), and 2-(1,2-dihydro-4-oxo-2-
thioxoquinazolin-3(4H)-yl)-5-bromo Benzoic Acid (12)
A mixture of 2 (0.01 mol) and anthranilic acid derivatives (0.01 mol)
in dioxane (30 mL) containing triethylamine (0.5 mL) was refluxed
for 8 h. The reaction mixture was cooled, and the solid obtained was
recrystallized from dioxane to give 10–12, respectively (Table I). IR
(kBr, cm−1)10: 3250 (NH), 1680, 1660 (2C O), 1274 (C S).
IR(kBr, cm−1)11: 3310 (NH), 1710, 1696 (2C O), 1276 (C S). MS
(m/z)11: 312 (M+, 13.7%), 253 (100%) (Chart 2).
IR (kBr, cm−1)12: 3208 (NH), 3034 (CH arom.), 1688, 1668 (2C O),
1268 (C S). MS (m/z) 12: 377 (M+, 7.5%), 331 (100%) (Chart 3).
4-Oxo-2-thioxo-1,4-dihydro-2H-quinazoline-3-carboxylic Acid
Ethyl Ester (13)
A mixture of 2 (0.01 mol) and ethylcarbamate (0.01 mol) in dioxane
(25 mL) containing triethylamine (0.5 mL) was refluxed for 4 h. The
reaction mixture was cooled, and the solid obtained was recrystallized
from ethanol to give 13 (Table I). IR (kBr, cm−1) 3302 (NH), 1700, 1690

Novel Quinazolinone Derivatives as Possible Antitumor Agents
69
CHART 1 The mass fragmentation pattern of compound 9.
(2C O), 1274(C S). δ 1.6 [t, 3H, CH3], 4.0 [q, 2H, CH2], 7.1–8.4 [m, 4H,
Ar-H], 10.8 [s, 1H, NH].
4-(4-Oxo-2-thioxo-1,4-dihydro-2H-quinazoline-3-yl)-benzoic
Acid Ethyl Ester (14)
A mixture of 2 (0.01 mol) and ethyl-p-aminobenzoate (0.01 mol) in
dioxane (25 mL) containing triethylamine (0.5 mL) was refluxed for
10 h. The reaction mixture was cooled, and the solid obtained was re-
crystallized from dioxane to give 14 (Table I). IR (kBr, cm−1) 3246
(NH), 1722, 1664 (2C O), 1270 (C S). δ 1.25 [t, 3H, CH3], 4.4 [q, 2H,

70
S. El-Sayed Barakat et al.
CHART 2 The mass fragmentation pattern of compound 11.

Novel Quinazolinone Derivatives as Possible Antitumor Agents
71
CHART 3 The mass fragmentation pattern of compound 12.

72
S. El-Sayed Barakat et al.
CH2], 7.2–8.2 [m, 8H, Ar-H], 9.6 [s, 1H, NH]. MS (m/z): 326 (M+, 1.1%),
253 (100%) (Chart 4).
3-(5-Chloro-pyridin-2-yl)-2-thioxo-2,3-dihydro-1H-
quinazolin-4-one (15)
A mixture of 2 (0.01 mol) and 2-amino-5-chloro-pyridine (0.01 mol)
in dioxane (30 mL) containing triethylamine (0.5 mL) was refluxed for
12 h. The reaction mixture was cooled, and the solid obtained was re-
crystallized from dioxane to give 15 (Table I). IR (kBr, cm−1): 3306
(NH), 3086 (CH arom.), 1702 (C O), 1268 (C S). δ 7.1–8.0 [m, 7H, Ar-
H], 9.2 [s, 1H, NH].
Antitumor Activity (In Vitro Study)
Reagents
1. Roswell Park Memorial Institute (RPMI) 1640 medium (sigma).
2. Ehrlich Ascites Carcinoma (EAC) cells suspension (2.5.105/mL).
3. Trypan blue dye. A stock solution was prepared by dissolving 1 g of
the dye in distilled water 100 mL. The working solution was then
prepared by diluting 1 mL of the stock solution with 9 mL of distilled
water. The stain was used then for staining the dead EAC cells.
4. The compounds tested were (3–15), (Table II).
Procedure
1. EAC cells were obtained by needle aspiration of the ascetic fluid
from preinoculated mice under aseptic conditions.14
2. The cells were tested for viability and contamination by staining a
certain cell volume of this fluid by an equal volume of the working
solution of trypan blue dye.15,16
3. The ascetic fluid was diluted with saline (1:10) to contain 2.5.106
cells on a hemocytometer.
4. In a set of sterile test tubes 0.1 mL of tumor cells suspension, 0.8 mL
RPMI 1640 media, and 0.1 mL of each tested compound (correspond-
ing to 100, 50, and 25 µg/mL) were mixed. The test tubes were incu-
bated at 37◦C for 2 h. Trypan blue exclusion test15,16 was carried out
to calculate the percentage of nonviable cells. Compounds producing
more than 70% nonviable cells were considered active.17
5. Doxorubicin (Adriablastina)R was taken as a reference.
No. of nonviable
Total No. of cells
% of nonviable cells =
× 100
(1)

Novel Quinazolinone Derivatives as Possible Antitumor Agents
73
CHART 4 The mass fragmentation pattern of compound 14.

74
S. El-Sayed Barakat et al.
TABLE II In Vitro Cytotoxic Activity of Some
Selected Synthesized Compounds
Nonviable cells (%)
Concentration (µg/mL)
Compound No.
100
50
25
IC50 (µg/mL)∗
3
4
5
6
7
8
9
11
10
0
20
0
0
20
0
10
20
0
30
100
0
0
10
0
0
10
0
0
10
0
20
55
0
0
0
0
0
0
0
0
0
0
0
>100
—
>100
—
—
>100
—
>100
>100
—
>100
35
12
14
15
Doxorubicin (reference)
20
∗IC50 > 100 (µg/mL) is considered to be inactive.
RESULTS
Chemistry
The treatment of methylanthranilate 1 with thiophosgene gave
the corresponding 2-isothiocyanato derivative 218 (Scheme 1). The
reactivity of isothiocyanato 2 towards some oxygen nucleophiles
was investigated. Thus, the reaction of isothiocyanato 2 with
ethanol as oxygen nucleophile under reflux yielded the corresponding
2-ethoxythiocarbonylamino-benzoic-acid methyl ester 3 (Scheme 1).
Also, 2-(2-methoxy-ethoxythiocarbonylamino)-benzoic acid methyl
ester 4 was obtained via a reaction of isothiocyanato derivative 2 with
methoxyethanol (Scheme 1).
It was planned to investigate the reactivity of isothiocyanato
2 toward an aromatic hydroxy compound. Thus, 3-hydroxypyridine
was reacted with isothiocyanato
2
to produce 2-(pyridine-3-
yloxythiocarbonylamino)-benzoic acid methyl ester 5 (Scheme 1).
On the other hand, the reactivity of isothiocyanato 2 toward some
nitrogen nucleophiles was investigated. Thus, the reaction of isothio-
cyanato 2 with ethanolamine and/or propanolamine in dioxane con-
taining a catalytic amount of triethylamine afforded the quinazolinone
derivatives 6 and 7, respectively (Scheme 1).

Novel Quinazolinone Derivatives as Possible Antitumor Agents
75
SCHEME 1
In addition, reaction of isothiocyanato 2 with methyl-3-amino-
crotonate yielded 3-(4-oxo-2-thioxo-1,4-dihydro-2H-quinazolin-3-yl)-
but-2-enoic acid methyl ester 8 in a good yield (Scheme 1).
The cyclocondensation of methylanthranilate 1 and/or anthranilic
acid derivatives with isothiocyanato 2 in dioxane/TEA furnished the
novel quinazolinone derivatives 9–12, respectively (Scheme 1).

76
S. El-Sayed Barakat et al.
SCHEME 2
Finally, the interaction of isothiocyanato derivative 2 with ethyl
carbamate or ethyl-p-aminobenzoate and/or 2-amino-5-chloro-pyridine
yielded the corresponding quinazolinone derivatives 13–15, respec-
tively (Scheme 2).
Antitumor Activity
The results of antitumor activity for the synthesized compounds showed
no activity against EAC.

Novel Quinazolinone Derivatives as Possible Antitumor Agents
77
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