Synthesis of some novel quinazolin-4(3H)-one hybrid molecules as potent urease inhibitors

Article abstract of DOI:10.1002/ardp.201800182

A new series of quinazolinone hybrid molecules containing coumarin, furan, 1,2,4-triazole and 1,2,4-thiadiazole rings was designed, synthesized, and screened for their urease inhibition activities. All newly synthesized compounds showed outstanding urease inhibitory potentials with IC₅₀ values ranging between 1.26 ± 0.07 and 7.35 ± 0.31 μg/mL. Among the series, coumarin derivatives (10a–d) exhibited the best inhibitory effect against urease in the range of IC₅₀ = 1.26 ± 0.07 to 1.82 ± 0.10 μg/mL, when compared to standard urease inhibitors such as acetohydroxamic acid and thiourea (IC₅₀ = 21.05 ± 0.96 and 15.08 ± 0.71 μg/mL, respectively). Molecular docking studies were also performed to analyze the binding mode of compound 10b, and supported the experimental results.

Full text of DOI:10.1002/ardp.201800182

Received: 12 June 2018
Revised: 2 October 2018
Accepted: 10 October 2018
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DOI: 10.1002/ardp.201800182
FULL PAPER
Synthesis of some novel quinazolin-4(3H)-one hybrid
molecules as potent urease inhibitors
Emre Menteşe1
Mustafa Emirik1
Gülay Akyüz1
Fatih Yılmaz2
Nimet Baltaş1
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1 Faculty of Arts and Sciences, Department of
Chemistry, Recep Tayyip Erdogan University,
Rize, Turkey
Abstract
A new series of quinazolinone hybrid molecules containing coumarin, furan, 1,2,4-
triazole and 1,2,4-thiadiazole rings was designed, synthesized, and screened for their
urease inhibition activities. All newly synthesized compounds showed outstanding
urease inhibitory potentials with IC50 values ranging between 1.26 ± 0.07 and
7.35 ± 0.31 μg/mL. Among the series, coumarin derivatives (10a–d) exhibited the best
inhibitory effect against urease in the range of IC50 = 1.26 ± 0.07 to 1.82 ± 0.10 μg/mL,
when compared to standard urease inhibitors such as acetohydroxamic acid and
thiourea (IC50 = 21.05 ± 0.96 and 15.08 ± 0.71 μg/mL, respectively). Molecular dock-
ing studies were also performed to analyze the binding mode of compound 10b, and
supported the experimental results.
2 Department of Chemistry and Chemical
Processing Technology, Vocational School of
Technical Studies, Recep Tayyip Erdogan
University, Rize, Turkey
Correspondence
Dr. Emre Menteşe, Faculty of Arts and
Sciences, Department of Chemistry, Recep
Tayyip Erdogan University, 53100 Rize,
Turkey.
Email: emre.mentese@erdogan.edu.tr
Funding information
Recep Tayyip Erdogan Üniversitesi,
Grant number: FBA-2017-720
K E Y W O R D S
coumarin, furan, molecular docking, quinazolin-4(3H)-one, thiadiazole, triazole, urease
inhibition
1
INTRODUCTION
acid and its derivatives,[9] triazoles, coumarins,[10] semicarba-
zones,[11] Schiff bases,[12] urea derivatives,[13] oxadiazoles,[14] and
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Urease is a nickel containing enzyme that catalyzes the hydrolysis of
urea to ammonia and carbon dioxide. This enzyme is known to be
one of the reasons of the diseases which are caused by Helicobacter
pylori, thus allows bacteria to live in the stomach at low pH and it
plays an important role in gastric ulcer, and even gastric cancer
diseases.[1–3] Also, urease in soils can cause excessive volatilization
of ammonia in urea fertilizer since it degrades urea too rapidly.[4,5]
Urease inhibition studies have been given attention by researchers in
recent years; some of the urease inhibitors have been reported, such
as hydroxamic acid derivatives, phosphorodiamidates, and imida-
zoles.[6] Unfortunately, some urease inhibitors cannot be used
in mouse experiments because of their toxicity.[7] Thus, it is needed to
synthesize new urease inhibitors with good activities. Urease
inhibitors can be classified into two groups: organic compounds
and organometallics.[8] The former category includes hydroxamic
piperidines.[15]
In recent years, considerable evidence has been found on the
importance of quinazolinone derivatives in the pharmaceutical
chemistry.[16–22] For example, they have attracted attention as an
important nucleus in the class of therapeutic agents because of their
wide range of biological activities.[23] Recently, 2-arylquinazolines
have been synthesized and evaluated for their cytotoxicity and
inhibition of topoisomerases.[24] In addition, a series of quinazoline
derivatives has been synthesized and characterized as antioxidants
and anti-inflammatory agents.[25] Also, quinazolinones containing
natural compounds (luotonin, rutaecarpine, tryptanthrin, chloroqu-
alone, and alloqualone (Figure 1)) are the pharmaceutically important
class of compounds, because of their diverse range of biological
activities such as anti-cancer, diuretic, anti-inflammatory, anti-
convulsant, and anti-hypertensive.[26,27]
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Arch Pharm Chem Life Sci. 2018;e1800182.
https://doi.org/10.1002/ardp.201800182
wileyonlinelibrary.com/journal/ardp
© 2018 Deutsche Pharmazeutische Gesellschaft
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FIGURE 1 The structures of luotonin, rutaecarpine, tryptanthrin, chloroqualone, and alloqualone
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Coumarins (2H-chromen-2-ones) are generally obtained from
plants and consist of a class of phenolic compounds. More than 1300
of coumarin derivatives have been identified from plants, bacteria, and
fungi. In 1820, coumarin was first obtained as a natural product and
nearby 150 species of coumarin were found in 30 diverse plant families
like Umbelliferae, Oleaceae, Clusiaceae, Guttiferae, Rutaceae. Couma-
rin is widely used as a pharmacophore in medicinal chemistry.[28–32]
Moreover, coumarin and its derivatives show rare side effects on
human body.[33] Therefore, medicinal properties of coumarin deriv-
atives are very important and they have been used for their many
pharmacological activities including antioxidant,[34] anticoagulant,[35]
antibacterial,[36] antitubercular,[37] antifungal,[38] antilipase,[39]
α-glucosidase,[16] urease,[40,41] and anticancer.[39] Recent modeling
simulations and high-throughput virtual screening studies have
showed that coumarin–triazoles hybrid molecules were also found
as potential urease inhibitors.[10]
2
RESULTS AND DISCUSSION
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2.1 Chemistry
The synthetic strategy pathway for the intermediates and target
compounds consisted of the reactions that are outlined in Schemes 1
and 2. Ethyl imidopropionate hydrochloride was reacted with
2-aminobenzamide in methanol to obtain compound 1. Compound
3 was prepared by simple alkylation of compound 1 with ethyl
bromoacetate and K2CO3 in anhydrous acetone and then was
transformed to acetohyrazide
4 by treatment with hydrazine
monohydrate in ethanol. Coumarin-3-carboxylic acid derivatives
were reacted with 1H-benzotriazole in the presence of SOCl2 in
dichloromethane to prepare 3-(1H-benzotriazol-1-ylcarbonyl)-2H-
chromen-2-ones (2a–d).[54] Compound 4 is the first intermediate on
the route to the other target compounds as shown in Scheme 2. The
ring closure reaction of molecule 4 with carbon disulfide in the
presence of KOH resulted in the formation of compound 5. Schiff
base bearing furan ring (6) was prepared by the reaction of
compound 4 with furfural in ethanol. Thiosemicarbazide derivative
(7) was prepared by the nucleophilic addition of acid hydrazide (4) to
ethyl isothiocyanate. The cyclization of compound 7 with cold-
concentrated sulfuric acid resulted in the formation of thiadiazole
derivative (8). On the other hand, intramolecular cyclization of
compound 7 in the presence of 1 M NaHCO3 under reflux resulted in
the formation of 1,2,4-triazole derivative (9). We have also
converted compound 4 to coumarin derivatives (10a–d) by the
reaction of acetohydrazide derivative (4) with corresponding 3-(1H-
benzotriazol-1-ylcarbonyl)-2H-chromen-2-ones (2a–d). The struc-
tures of the new compounds were confirmed by 1H NMR, 13C NMR
spectroscopy and mass spectra. The spectroscopic investigations of
newly synthesized compounds are in accordance with the proposed
structure.
Five membered nitrogen and, or, oxygen containing heterocycles
are an important class of compounds in medicinal chemistry. 1,3,4-
Oxadiazole, furan, 1,3,4-triazoles and 1,3,4-thiadiazoles are the
common and useful structural core in medicinal chemistry for designing
new drug candidates. Compounds containing these moieties have been
evaluated against a broad spectrum of pharmacological activities.[42–51]
Our research group has a long standing interest in research to
identify whether hybrid molecules which include benzimidazole,
coumarin, 1,2,4-triazole and 1,2,4-thiadiazole moieties, show a high
biological effect especially enzyme inhibitions such as urease, lipase,
α-glucosidase, and xanthine oxidase.[16,39,43,52–55] In the view of above
facts, the current study describes the synthesis and urease inhibition
studies of different quinazolinone hybrid compounds containing
coumarin, isothiocyanate, furan, 1,2,4-triazole and 1,2,4-thiadiazole
moieties. Taking these into consideration, the aim of the present work
is to understand the effect of coumarin, furan, 1,2,4-triazole and
1,2,4-thiadiazole moieties with quinazolinone on urease inhibition.

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SCHEME 1 Synthetic route of compound 4
SCHEME 2 The synthetic path of the target compounds

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2.2 Biological evaluation
this study, we observed that heterocyclic group on N-3 position of
quinazolinone ring plays an important role in the inhibitor activity
(Figure 2). Also, dose-response plot study of the most active compound
(compound 10b) is shown in Figure 3.
All the synthesized compounds were evaluated for their in vitro
inhibitory activity against Jack bean urease (JBU) (Cas No.: 9002-13-5).
Acetohydroxamic acid which has been clinically used for the treatment
of urinary tract infections and thiourea were used as standard
inhibitors. In this work, lower IC50 values of compounds display a
higher enzyme inhibitory effectiveness. Initially, all the synthesized
compounds were screened at 10 μg/mL, the standards at 60 µg/mL
final concentration. The results showed that all newly synthesized
compounds exhibited potent urease inhibitory activity in the range of
IC50 = 1.26 ± 0.07 to 7.35 ± 0.31 μg/mL, when compared to the
standards such as acetohydroxamic acid (IC50 = 21.05 ± 0.96 μg/mL)
and thiourea (IC50 = 15.08 ± 0.71 μg/mL). Among these compounds, 6
and 10a–d series exhibited the best inhibitory effect against urease
(Table 1). Compounds 10a–d bearing coumarin ring at the N-3 position
on the quinazolinone ring showed outstanding urease inhibitory
potentials with IC50 values ranging between 1.26 ± 0.07 and
1.82 ± 0.10 μg/mL (Table 1). Among the coumarin–quinazolinone
hybrid molecules, compound 10b having bromo substituent at
6-position of coumarin ring was found to be the most potent urease
inhibitor with IC50 value of 1.26 ± 0.07 μg/mL. Compound 6 bearing
furan ring at the N-3 position on the quinazolinone nucleus was found
the second most active compound with IC50 value of 1.68 ± 0.08 μg/
mL. Compound 7 contains thiosemicarbazide part on the N-3 position
of quinazolinone ring when compared with compounds 8 and 9 having
triazole and thiadiazole moiety on the 3-position of quinazolinone
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2.3 In silico docking study
Molecular docking studies were performed using Maestro Molecular
Modeling platform (version10.5) by Schrödinger, LLC[56] to investigate
possible binding interactions of the protein–ligand complexes. The
crystal structure of JBU was retrieved from the Protein Data Bank
using PDBID 3LA4.[57] The docking procedures were performed as
described in our previous articles.[47,50] The compounds 10a, 10b, and
10d showed better docking scores ranging from −7.38 to −9.11 kJ/mol
than the standard inhibitors acetohydroxamic acid (−6.93 kJ/mol) and
thiourea (−3.71 kJ/mol) in Table 1. Because of having better
experimental result, the compound 10b was further analyzed in detail.
According to the docking studies, the best possible binding pose
and protein–ligand interactions diagram of compound 10b are shown
in Figure 4. In the best orientation of compound 10b was anchored the
active site through CO···H─N and CO···H─O─H···N hydrogen bonds
with amino acid residues HIS594 and HIS593, respectively. The
CYS592 (marked as CME592) is a key residue located at the mobile flap
covering the active site and forming hydrogen bond with quinazoli-
none nitrogen of compound 10b at distance 2.13 Å. The π À π
stacking interaction with the amino acid residues of Phe605
through the coumarin ring of 10b contributed to the binding
energy of protein–ligand complex as well.
part, respectively. The inhibitory potential of compounds
8
(IC50 = 2.05 ± 0.11 μg/mL) and 9 (IC50 = 4.00 ± 0.21 μg/mL) was found
greater than that of 7 (IC50 = 6.32 ± 0.36 μg/mL). This indicates that
quinazolinone bearing triazole and thiadiazole nucleus, in general, are
more potent that their open-chain thiosemicarbazide counterparts. In
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3
CONCLUSION
In conclusion, a new series of quinazolinone hybrid molecules bearing
coumarin, triazole, thiadiazole, oxadiazole, furan, and thiosemicarba-
zide functionalities has been synthesized successfully and evaluated
for their in vitro urease activities. All of the quinazolinone derivatives
showed outstanding urease inhibitory potentials with IC50 values
ranging between IC50 = 1.26 ± 0.07 and 7.35 ± 0.31 μg/mL, when
compared to the standards such as acetohydroxamic acid and thiourea
(IC50 = 21.05 ± 0.96 and 15.08 ± 0.71 μg/mL, respectively). It is clear
from this study that combination of quinazolinone ring with coumarin
cycle increased the urease inhibitory activities with respect to the
combination with five-membered heterocycles like oxadiazole, furane,
thiadiazole, and triazole ring. Furthermore, the substitution on
coumarin cycle was found to have positive effect on urease inhibitory
activities. Bromo substitution on the 6-position of coumarin cycle was
found to have more effect on the activity with IC50 value of
1.26 ± 0.07 μg/mL with respect to chloro substation on the 6-position
and the substation of diethylamino group on 7-position of coumarin
cycle with IC50 value of 1.38 ± 0.05 and 1.36 ± 0.08 μg/mL, respec-
tively. The molecular docking studies were also performed to
analyze the binding mode of compounds 10b and supported the
experimental results. The results could be inspiration for further
TABLE 1 The inhibition effects of quinazolinone derivatives against
Jack bean urease with docking scores
Compound no.
IC50 (μg/mL)
3.80 ± 0.13
4.98 ± 0.21
7.35 ± 0.31
2.25 ± 0.11
1.68 ± 0.08
6.32 ± 0.36
2.05 ± 0.11
4.00 ± 0.21
1.82 ± 0.10
1.26 ± 0.07
1.38 ± 0.05
1.36 ± 0.08
21.05 ± 0.96
15.08 ± 0.71
r2
Docking score
−5.17
1
0.9886
0.9766
0.9785
0.9875
0.9923
0.9777
0.9869
0.9854
0.9876
0.9912
0.9909
0.9861
0.9868
0.9766
3
−4.86
4
−5.06
5
−4.37
6
−7.15
7
−5.41
8
−6.71
9
−6.66
10a
−7.38
10b
−8.53
10c
−5.89
10d
−9.11
Acetohydroxamic acid
Thiourea
−6.93
−3.71

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FIGURE 2 Comparison of structure–activity relationship between compounds 5, 6, 8–10
structural modifications and investigations of potential antiurease
mass spectra were obtained for the synthesized compounds on
Thermo Scientific Quantum Access max LC-MS spectrometer.
The InChI codes of the investigated compounds together with
some biological activity data are provided as Supporting Information.
activity within quinazolin-4(3H)-one derivatives.
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4
EXPERIMENTAL
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4.1 Chemistry
4.1.2 Synthesis of 2-ethylquinazolin-4(3H)-one (1)
In a balloon with a round bottom, 1.36 g (0.01 mol) 2-aminobenzamide
and 1.38 g (0.012 mol) iminoester hydrochloride were dissolved in
methanol. The mixture was stirred for 10 h at room temperature. The
end of the reaction was monitored by TLC (ethyl acetate/hexane, 3:1).
The mixture was poured into water and the precipitated product was
filtered off, washed with water, and recrystallized from ethanol/water,
3:1.
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4.1.1 General
The chemicals were supplied from Merck, Aldrich, and Fluka. Melting
points were taken in capillary tubes on a Stuart SMP30 melting point
apparatus and uncorrected. Reactions were monitored by thin-layer
chromatography (TLC) using precoated aluminum sheets (silica gel 60 F
2.54 0.2 mm thickness). The mobile phase was ethyl acetate and
hexane (2:1 or 3:1) and detection was made using UV light. 1H NMR
and 13C NMR spectra were recorded on a Varian-Mercury 400 (1H,
400 MHz; 13C, 100 MHz) spectrometer using DMSO-d6 as solvent and
TMS as internal standard. All chemical shifts were reported in ppm. The
Yield 99%, mp: 231–232°C, IR (νmax, cm−1): 3165 (NH), 1672
1
�
�
(C O), 1606 (C N). H NMR spectrum (400 MHz, DMSO-d6), δ, ppm
(J, Hz): 12.40 (1H, s, NH), 8.10 (1H, d, J = 7.6 Hz, ArH), 7.72 (1H, t,
J = 7.6 ArH), 7.56 (1H, d, J = 6.8 Hz, ArH), 7.47 (1H, d, J = 6.8 Hz, ArH),
3.45 (2H, q, J = 6.8 Hz, CH2); 1.09 (3H, t, J = 6.8 Hz, CH3). 13C NMR
(100 MHz, DMSO-d6), δ, ppm: 10.78 (CH3), 40.12 (CH2), ArC [120.50,
�
121.25 (C), 126.14, 126.72, 131.74, 133.82 (CH)], 155.23 (C N),
�
161.78 (C O).
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4.1.3 Synthesis of ethyl [2-ethyl-4-oxoquinazolin-3-
(4H)-yl]acetate (3)
Anhydrous K2CO3 3.45 g (0.025 mol) was added to a solution of the
appropriate compound 1 (0.010 mol) in acetone and the mixture was
stirred for 15 min at room temperature. Ethyl bromoacetate 1.67 g
(0.010 mol) was then added and the mixture was stirred for 3 h. The
end of the reaction was monitored by TLC (ethyl acetate/hexane, 3:1).
The product was precipitated by the addition of water, filtered off,
washed with water, and recrystallized from ethanol/water, 3:2.
Yield 65%, mp: 124–126°C, IR (νmax, cm−1): 1671 (C O), 1667
�
(C O), 1594 (C N), 1175 (C─O). 1H NMR spectrum (400 MHz,
�
�
DMSO-d6), δ, ppm (J, Hz): 8.30 (1H, d, J = 7.6 Hz, ArH), 8.10 (1H, d,
FIGURE 3 Dose-response plot for compound 10b

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FIGURE 4 Ligand interaction diagrams and the binding pose of compound 10b in the active site of JBU. For clarity, only interacting
residues are labeled. Hydrogen bonding interactions are shown by yellow dashes
J = 7.6 Hz, ArH), 7.57–7.50 (2H, m, ArH), 4.27 (2H, s, NCH2), 3.42 (2H,
q, J = 6.8 Hz, CH2); 1.05 (3H, t, J = 6.8 Hz, CH3). 13C NMR (100 MHz,
DMSO-d6), δ, ppm: 13.78 (CH3), 40.12 (CH2), 40.61 (CH2), 44.88
(NCH2), ArC [120.09 (C), 126.67, 127.40, 128.92, 128.97, 131.46 (CH),
6–7 with 37% HCl. The precipitated solid was filtered, washed
thoroughly with water, dried, and recrystallized from ethanol/water
(2:1).
Yield 52%, mp: 177–178°C, IR (vmax/cm−1): 3335 (NH); 1645 (CO);
146.44 (C)], 158.23 (CN), 161.78 (C O).
1595 (C N). 1H NMR (400 MHz, DMSO-d6), δ, ppm: 8.10 (1H, d,
�
�
J = 6.8 Hz, ArH); 7.82 (1H, t, J = 6.8 Hz, ArH); 7.65 (1H, d, J = 7.2 Hz,
ArH); 7.52 (1H, t, J = 7.2 Hz, ArH); 5.40 (2H, s, NCH2); 2.93 (2H, q,
J = 6.0 Hz, CH2); 1,26 (3H, t, J = 6.0 Hz, CH3). 13C NMR (100 MHz,
DMSO-d6), δ, ppm: 11.04 (CH3); 27.55 (CH2); 38.59 (NCH2); ArC:
[119.90 (C); 126.70; 127.27; 127.44; 135.40 (CH); 147.19 (C)]; 157.97
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4.1.4 Synthesis of 2-(2-ethyl-4-oxoquinazolin-3(4H)-
yl)acetohydrazide (4)
Hydrazine monohydrate 2.50 g (0.050 mol) was added to a solution of
the compound 3 (0.01 mol) in ethanol (10 mL). The mixture was stirred
for 3 h. The end of the reaction was monitored by TLC (ethyl acetate/
hexane, 3:1). The product was filtered off, dried, and recrystallized
from ethanol.
�
(C N); 159.90 (oxadiazole C2); 161.43 (CO); 178.28 (oxadiazole C5).
LC-MS, m/z: 288.74 [M+H]+.
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4.1.6 Synthesis of 2-(2-ethyl-4-oxoquinazolin-3(4H)-
Yield 79%, mp: 259–260°C, IR (vmax/cm−1): 3335 (NH─NH2);
yl)-Nʹ-[2-furylmethylene]acetohydrazide (6)
1
�
�
1675 (C O); 1670 (C O); 1597 (CN). H NMR (400 MHz, DMSO-d6),
δ, ppm: 9.40 (1H, s, NH); 8.07 (1H, d, J = 7.6 Hz, ArH); 7.80 (1H, t,
J = 7.2 Hz, ArH); 7.62 (1H, d, J = 8.0 Hz, ArH); 7.48 (1H, t, J = 7.2 Hz,
ArH); 4.71 (2H, s, NCH2); 4.27 (2H, s, NH2); 2.68 (2H, q, J = 7.2 Hz,
CH2); 1.25 (3H, t, J = 7.2 Hz, CH3). 13C APT (100 MHz, DMSO-d6), δ,
ppm: 10.97 (CH3); 27.64 (CH2); 44.40 (NCH2); ArC [120.20 (C); 126.60;
Compound 4 2.46 g (0.01 mol) was dissolved in 10 mL ethanol. A total
of 0.96 g (0.01 mol) furfural was added into the mixture balloon. A few
drops of acetic acid were added in the mixture as a catalyst. The
balloon was refluxed for 12 h. The precipitated solid was filtered,
washed thoroughly with ethanol, and dried.
Yield 62%, mp: 220–222°C IR (vmax/cm−1): 3184 (NH); 1677
�
126.75; 127.25; 134.83 (CH); 147.40 (C)]; 158.62 (CN); 161.67 (C O);
+
+
166.83 (C O). LC-MS, m/z: 246.26 [M+H] ; 268.93 [M+Na] .
(C O); 1596, 1570 (C N). 1H NMR (400 MHz, DMSO-d6), δ, ppm:
�
� �
�
11.74 (1H, s, NH); 8.08 (1H, d, J = 6,0 Hz, ArH); 7.93 (1H, s, N CH);
7.83 (2H, s, ArH); 7.64 (1H, d, J = 4.4 Hz, ArH); 7.49 (1H, s, ArH); 6.93
(1H, s, ArH); 6.63 (1H, s, ArH); 5.21–4.86 (2H, s, NCH2, cis/trans 77.5/
22.5); 2.76 (2H, q, J = 4.4 Hz, CH2); 1.25 (3H, t, J = 4.4 Hz, CH3).
13C NMR (100 MHz, DMSO-d6), δ, ppm: 11.01 (CH3); 27.66 (CH2);
44.76 (NCH2); ArC [112.66; 114.56 (CH); 120.05 (C); 126.61; 126.82;
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4.1.5 Synthesis of 2-ethyl-3-[(5-mercapto-1,3,4-
oxadiazol-2-yl)methyl]quinazolin-4(3H)-one (5)
In a balloon with a round bottom, compound 4 2.46 g (0.01 mol) was
dissolved in ethanol. A total of 0.56 g (0.01 mol) KOH was dissolved
in water and added in the balloon, then 3.04 g (0,04 mol) CS2 was
added into the mixture. The mixture of reaction was refluxed for 7 h.
The solution was cooled to room temperature and acidified to pH
�
127.29; 134.96 (CH); 147.47 (C)]; 149.31 (CN); 158.72 (C N,
�
quinazolinone C2); 161.78 (CO); 168.65 (C O). LC-MS, m/z: 325.06
[M+H]+.

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4.1.7 Synthesis of N-ethyl-2-[(2-ethyl-4-
δ, ppm: 13.61 (1H, s, NH); 8.08 (1H, d, J: 8.0 Hz, ArH); 7.82 (1H, s, ArH);
7.66 (1H, s, ArH); 7.50 (1H, s, ArH); 5.41 (2H, s, NCH2); 4.16 (2H, d,
J = 8.0 Hz, CH2); 4.12 (2H, s, CH2); 1.28 (3H, s, CH3); 1.26 (3H, s, CH3).
13C NMR (100 MHz, DMSO-d6), δ, ppm: 11.19; 13.56 (CH3); 27.64;
38.63 (CH2); ArC [119.99 (CH); 126.69; 127.20; 127.40; 135.33 (C);
oxoquinazolin-3(4H)-yl)acetyl]-
hydrazinecarbothioamide (7)
A mixture of hydrazide 4 (0.01 mol) in ethanol (15 mL) and ethyl
isothiocyanate (0.011 mol) was refluxed for 3 h. The solution was
cooled and a white solid appeared. The precipitated product was
filtrated and recrystallized from ethanol to obtain the desired pure
product 6.
�
�
�
147.30; 147.87; (CH)]; 158.29 (C N); 161.41 (C O); 166.98 (C O).
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4.1.10 Synthesis of compounds 10a–d
Yield 74%, mp: 211–212°C IR (vmax/cm−1): 3330, 3301 (NH─NH);
In a balloon with a round bottom, compound 4 2.46 g (0.01 mol) and
0.01 mol appropriate compound 2a–d were dissolved in ethanol. The
mixture was refluxed for 12 h. The precipitated products were filtrated
and washed with hot ethanol to obtain the desired pure products
10a–d.
1682, 1660 (C O); 1593 (C N); 1179 (C S). 1H NMR (400 MHz,
DMSO-d6), δ, ppm: 10.27 (1H, s, NH); 9.67 (1H, s, NH); 8.11 (1H, d,
J = 8.0 Hz, ArH); 7.94 (1H, s, NH); 7.80 (1H, d, J = 7.2 Hz, ArH); 7.66
(1H, d, J = 8.0 Hz, ArH); 7.51 (1H, t, J = 7.2 Hz, ArH); 4.87 (2H, s, NCH2);
3.48 (2H, d, J = 7.2 Hz, CH2); 2.81 (2H, d, J = 7.2 Hz, CH2); 1.29 (3H, t,
J = 7.2 Hz, CH3); 1.12 (3H, t, J = 7.2 Hz, CH3). 13C NMR (100 MHz,
DMSO-d6), δ, ppm: 11.17, 14.85 (CH3); 39.03 (CH2); 40.48 (CH2);
44.98 (NCH2); ArC [120.07 (C); 126.56; 126.68; 126.79; 126.92;
�
�
�
Nʹ-[(2-Ethyl-4-oxoquinazolin-3(4H)-yl)acetyl]-2-oxo-2H-
coumarin-3-carbohydrazide (10a)
Yield 75%, mp: 297–298°C, IR (vmax/cm−1): 3300 (NH─NH); 1713
�
�
127.35; 135.03 (CH); 147.47 (C)]; 158.66 (C N); 161.95 (C O);
�
�
(C O coumarin); 1691, 1676, 1666 (C O); 1598 (CN); 1201 (C─O).
1H NMR (400 MHz, DMSO-d6), δ, ppm: 11.13 (1H, s, NH); 10.59 (1H, s,
NH); 8.88 (1H, s, coumarin H4); 8.10 (1H, d, J = 7.6 Hz, ArH); 8.00 (1H,
d, J = 7.2 Hz, ArH); 7.80 (2H, m, ArH); 7.64 (1H, d, J = 8.0 Hz, ArH); 7.51
(3H, m, ArH); 4.93 (2H, s, NCH2); 2.83 (2H, d, J = 8.0 Hz, CH2); 1.28 (3H,
t, J = 8.0 Hz, CH3). 13C NMR (100 MHz, DMSO-d6), δ, ppm: 10,98
(CH3); 27.60 (CH2); 44.23 (NCH2); ArC [116.69 (CH); 118.53; 118.74;
120.11 (C); 125.67; 126.67; 126.86; 127.32; 130.81; 134.88; 134.96
(CH); 147.37 (C)]; 148.50 (coumarin C4); 154.41 (coumarin C3); 158.52
+
�
�
167.47 (C O); 170.90 (C S). LC-MS, m/z: 333.81 [M+H] , 355.86
[M+Na]+.
|
4.1.8 Synthesis of 2-ethyl-3-{[5-(ethylamine)-1,3,4-
thiadiazol-2-yl]methyl}quinazolin-4(3H)-one (8)
The compound 4 (0.01 mol) was dissolved with cold H2SO4 in the ice
bath. The mixture was stirred in ice bath for nearly an hour and then at
room temperature nearly an hour too. At the end of this time, the
mixture was taken in a beaker filled with ice and the product was
precipitated by neutralization with NH3. The product was filtered off
and recrystallized from ethanol.
�
�
�
�
(C N); 159.50 (C O); 160.18 (C O); 161.67 (C O quinazolinone);
165.28 (CO coumarin). LC-MS, m/z: 419.03 [M+H]+, 441.00 [M+Na]+.
6-Bromo-Nʹ-[(2-ethyl-4-oxoquinazolin-3(4H)-yl)acetyl]-2-oxo-
2H-chromene-3-carbohydrazide (10b)
Yield 48%, mp: 186–187°C, IR (vmax/cm−1): 3225 (NH); 1676
(C O); 1593, 1567 (C N). 1H NMR(400 MHz, DMSO-d6), δ, ppm:
9.43 (1H, s, NH); 8.15 (1H, dd, J = 7.6 Hz, ArH); 7.83 (1H, d, J = 8.0 Hz,
ArH); 7.73 (1H, s, NH); 7.66 (1H, d, J = 8.0 Hz, ArH); 7.54 (1H, m, ArH);
5.44 (2H, s, NCH2); 3.25 (2H, t, J = 8.0 Hz, CH2); 3.04 (2H, d, J = 8.0 Hz,
CH2); 1.28 (3H, t, J = 8.0 Hz, CH3); 1.13 (3H, t, J = 8.0 Hz, CH3).
13C NMR (100 MHz, DMSO-d6), δ, ppm: 10.99, 14.66 (CH3); 27.66
(CH2); 42.19 (CH2); 44.43 (NCH2); ArC [120.22 (C); 126.69; 127.41;
134.84; 135.18 (CH); 147.43 (C)]; 152.26 (thiadiazol C2); 158.64
�
�
Yield 65%, mp >300°C. 1H NMR (400 MHz, DMSO-d6), δ, ppm: 11.13
(1H, s, NH); 10.57 (1H, s, NH); 8.86 (1H, s, coumarin H4); 8.25 (1H, s,
ArH); 8.09 (1H, d, J = 8.0 Hz, ArH); 7.89 (2H, m, ArH); 7.64 (1H, d,
J = 8.0 Hz, ArH); 7.48 (2H, t, J = 8.0 Hz, ArH); 4.93 (2H, s, NCH2); 2.83
(2H, d, J = 8.0 Hz, CH2); 1.28 (3H, t, J = 8.0 Hz, CH3). 13C NMR
(100 MHz, DMSO-d6), δ, ppm: 10.98 (CH3); 27.58 (CH2); 44.22 (NCH2);
ArC [117.15 (C); 118.99; 119.80 (CH); 120.10; 120.60 (C); 126.68;
126.88; 127.32; 132.60; 134.98; 136.97 (CH); 147.08 (C)]; 147.37
�
�
�
(C N); 161.70 (C O); 166.84 (C N); 170.20 (thiadiazol C5). LC-MS,
m/z: 316.02 [M+H]+, 337.93 [M+Na]+.
�
(coumarin C4); 153.44 (coumarin C3); 158.52 (CN); 159.31 (C O);
�
�
159.66 (CO); 161.67 (C O quinazolinone); 165.35 (C O coumarin).
6-Chloro-Nʹ-[(2-ethyl-4-oxoquinazolin-3(4H)-yl)acetyl]-2-oxo-
2H-chromene-3-carbohydrazide (10c)
|
4.1.9 Synthesis of 2-ethyl-3-[(4-ethyl-5-mercapto-
4H-1,2,4-triazol-3-yl)methyl]quinazolin-4(3H)-one (9)
Yield 70%, mp >300°C. 1H NMR (400 MHz, DMSO-d6), δ, ppm: 11.13
(1H, s, NH); 10.58 (1H, s, NH); 8.82 (1H, s, coumarin H4); 8.12 (1H, s,
ArH); 8.09 (1H, d, J = 8.0 Hz, ArH); 7.79 (2H, m, ArH); 7.64 (1H, d,
J = 8.0 Hz, ArH); 7.55 (2H, t, J = 8.0 Hz, ArH); 4.93 (2H, s, NCH2); 2.83
(2H, d, J = 8.0 Hz, CH2); 1.26 (3H, t, J = 8.0 Hz, CH3). 13C NMR
(100 MHz, DMSO-d6), δ, ppm: 10.98 (CH3); 27.58 (CH2); 43.22 (NCH2);
ArC [117.15 (C); 118.75; 119.87 (CH); 120.10; 120.12 (C); 126.68;
126.88; 127.32; 129.31; 129.59; 134.97 (CH); 147.14 (C)]; 147.37
In a balloon with a round bottom, 1 M 15 mL NaHCO3 solution and
0.5 g compound 7 were refluxed for 12 h. At the end of this time, the
mixture was taken in a beaker with water and the product was
precipitated by neutralization with HCl. The product was filtered off
and recrystallized from ethanol.
Yield 75%, mp: 297–298°C, IR (vmax/cm−1): 2757 (SH), 1672
1
�
�
(C O), 1596, 1576 (C N), 1280 (CS). H NMR (400 MHz, DMSO-d6),

8 of 9
MENTEŞE ET AL.
|
�
�
(coumarin C4); 153.04 (coumarin C3); 158.04 (C N); 159.53 (C O);
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�
�
159.70 (CO); 161.67 (C O quinazolinone); 165.34 (C O coumarin).
7-(Diethylamino)-Nʹ-[(2-ethyl-4-oxoquinazolin-3(4H)-yl)acetyl]-
2-oxo-2H-chromene-3-carbohydrazide (10d)
Yield 68%, mp: 280–281°C. 1H NMR (400 MHz, DMSO-d6), δ, ppm:
11.05 (1H, s, NH); 10.46 (1H, s, NH); 8.68 (1H, s, coumarin H4); 8.09
(1H, d, J = 8.0 Hz, ArH); 7.79 (1H, s, ArH); 7.68 (2H, m, ArH); 7.48 (1H, s,
ArH); 6.81 (1H, d, J = 8.0 Hz, ArH); 6.60 (1H, s, ArH); 4.92 (2H, s, NCH2);
3.46 (4H, m, CH2); 3.30 (2H, s, CH2); 2.81 (2H, d, J = 8.0 Hz, CH2); 1.25
(3H, s, CH3); 1.24 (3H, s, CH3); 1.11 (3H, s, CH3). 13C NMR (100 MHz,
DMSO-d6), δ, ppm: 10,98 (CH3); 27.58 (CH2); 43.22 (NCH2); ArC
[96.36 (CH); 108.05; 108.11 (C); 110.80 (CH); 120.10 (C); 126.67;
126.86; 127.29; 132.28; 134.96 (CH); 147.37 (C)]; 148.82 (coumarin
�
C4); 153.28 (coumarin C3); 157. 86 (CN); 158.56 (C N); 160.61
�
�
�
O
(C O); 161.67 (C O); 161.77 (CO quinazolinone); 165.11 (C
coumarin).
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|
4.2 Urease inhibition assay
Urease is an enzyme that catalyzes the hydrolysis of urea into carbon
dioxide and ammonia. The production of ammonia was measured by
indophenol method and used to determine the urease inhibitory
activity.[42,58,59] The percentage remaining activity was calculated
from the formula: % Remaining Activity = [(ODtest)/(ODcontrol) × 100].
Thiourea and acetohydroxamic acid were used as standard inhibitors.
In order to calculate IC50 values, different concentrations of
synthesized compounds and standards were assayed at the same
reaction conditions.
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Y. F. Jin, H. T. M. Van, M. V. Chau, Y. Kwon, T. N. Le, W. J. Cho, Eur. J.
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ACKNOWLEDGMENTS
[25] K. P. Rakesh, H. M. Manukumar, D. C. Gowda, Bioorg. Med. Chem. Lett.
2015, 25, 1072.
[26] T. Panneerselvam, P. V. Kumar, C. R. Prakash, S. Raja, Toxicol. Environ.
Chem. 2011, 93, 643.
[27] O. O. Ajani, D. V. Aderohunmu, E. N. Umeokoro, A. O. Olomieja,
Bangl. J. Pharmacol. 2016, 11, 716.
This work was supported by Recep Tayyip Erdogan University
Scientific Research Project Unit (BAP) under project number of
FBA-2017-720. Authors thank Recep Tayyip Erdogan University for
this support.
[28] P. Borah, P. S. Naidu, P. J. Bhuyan, Tetrahedron Lett. 2012, 53, 5034.
[29] S. N. Mangasuli, K. Hosamani, P. Satapute, S. D. Joshi, Chem. Data
Collect. 2018, 15–16, 115.
CONFLICT OF INTEREST
[30] Q. Shen, Q. Peng, J. L. Shao, X. F. Liu, Z. S. Huang, X. Z. Pu, L. Ma, Y. M.
Li, A. S. C. Chan, L. Q. Gu, Eur. J. Med. Chem. 2005, 40, 1307.
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26, 3731.
The authors declare no conflict of interest.
ORCID
Emre Menteşe
http://orcid.org/0000-0002-3408-8202
[33] J. Dandriyal, R. Singla, M. Kumar, V. Jaitak, Eur. J. Med. Chem. 2016,
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SUPPORTING INFORMATION
Additional supporting information may be found online in the
Supporting Information section at the end of the article.
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How to cite this article: Menteşe E, Akyüz G, Yılmaz F,
Baltaş N, Emirik M. Synthesis of some novel quinazolin-4
(3H)-one hybrid molecules as potent urease inhibitors. Arch
Pharm Chem Life Sci. 2018;1–9.
https://doi.org/10.1002/ardp.201800182
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