Reactivity and Anticancer Assessment of 4-Hydroxyquinoline Derivatives

Article abstract of DOI:10.1134/S1070428020020219

Abstract: Ethyl 4-hydroxy-7-(trifluoromethyl)quinoline-3-carboxylate (1) exhibits a moderate cytotoxic activity against the MCF-7 mammary gland cancer cell line and HePG2 hepatocellular carcinoma cell line and a weak activity against the HCT-116 human colorectal carcinoma cell line. In order to enhance the cytotoxic activity of this compound, it was modified by changing the side-chain substituent and/or forming a new heterocyclic ring fused to the pyridine ring. Heating compound 1 with chloroacetyl chloride gave a mixture of two isomeric O-acylation products ethyl 4-(2-chloroacetoxy)-7-(trifluoromethyl)-quinoline-3-carboxylate and 3-chloro-8-(trifluoromethyl)-2H-pyrano[3,2-c]quinoline-2,4(3H)-dione, whereas the reaction with acetyl chloride in NaOH formed an N-acylation product 1-acetyl-4-oxo-7-(trifluoromethyl)-1,4-dihydroquinoline-3-carboxylic acid. The reactions of compound 1 with urea, thiourea, hydrazine hydrate, hydroxylamine, o-phenylenediamine, phenyl isothiocyanate, and ethyl acetoacetate yielded the corresponding condensation products 1-[4-oxo-7-(trifluoromethyl)-3,4-dihydroquinoline-3-carbonyl)]urea, 1-[4-oxo-7-(trifluoromethyl)-3,4-dihydroquinoline-3-carbonyl)]thiourea, 7-(trifluoromethyl)-1,2-dihydropyrazolo[4,3-c]quinolin-3-one, 7-(trifluoromethyl)isoxazolo[4,5-c]quinolin-3(2H)-one, 3-(trifluoromethyl)-13H-benzo[2,3][1,4]diazepino[6,5-c]quinolin-7-ol, 3-phenyl-2-thioxo-8-(trifluoromethyl)-2,3-dihydro-4H-[1,3]oxazino[5,6-c]quinolin-4-one and ethyl 8-(trifluoromethyl)-2-methyl-4-oxo-4H-pyrano[3,2-c]quinolone 3-carboxylate, respectively. The structures of the synthesized compounds were confirmed by elemental analysis and spectral data.

Full text of DOI:10.1134/S1070428020020219

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2020, Vol. 56, No. 2, pp. 307–314. © Pleiades Publishing, Ltd., 2020.
Reactivity and Anticancer Assessment
of 4-Hydroxyquinoline Derivatives
M. K. A. Regala, S. S. Shabanaa, and S. A. El-Metwallyb,*
a Chemistry Department, Faculty of Science, Ain Shams University, Cairo, 11566 Egypt
b Basic Science Department, Higher Technological Institute, 10 th of Ramadan City, 44629 Egypt
*e-mail: soadawad100@yahoo.com
Received August, 26, 2019; revised December 06, 2019; accepted December 20, 2019
Abstract—Ethyl 4-hydroxy-7-(trifluoromethyl) quinoline-3-carboxylate (1) exhibits a moderate cytotoxic ac-
tivity against the MCF-7 mammary gland cancer cell line and HePG2 hepatocellular carcinoma cell line and
a weak activity against the HCT-116 human colorectal carcinoma cell line. In order to enhance the cytotoxic
activity of this compound, it was modified by changing the side-chain substituent and/or forming a new het-
erocyclic ring fused to the pyridine ring. Heating compound 1 with chloroacetyl chloride gave a mixture of
two isomeric O-acylation products ethyl 4-(2-chloroacetoxy)-7-(trifluoromethyl)-quinoline-3-carboxylate
and 3-chloro-8-(trifluoromethyl)-2H-pyrano[3,2-c]quinoline-2,4(3H)-dione, whereas the reaction with acetyl
chloride in NaOH formed an N-acylation product 1-acetyl-4-oxo-7-(trifluoromethyl)-1,4-dihydroquinoline-
3-carboxylic acid. The reactions of compound 1 with urea, thiourea, hydrazine hydrate, hydroxylamine, o-phen-
ylenediamine, phenyl isothiocyanate, and ethyl acetoacetate yielded the corresponding condensation products
1-[4-oxo-7-(trifluoromethyl)-3,4-dihydroquinoline-3-carbonyl)]urea, 1-[4-oxo-7-(trifluoromethyl)-3,4-dihydro-
quinoline-3-carbonyl)]thiourea, 7-(trifluoromethyl)-1,2-dihydropyrazolo[4,3-c]quinolin-3-one, 7-(trifluorome-
thyl)isoxazolo[4,5-c]quinolin-3(2H)-one, 3-(trifluoromethyl)-13H-benzo[2,3][1,4]diazepino[6,5-c]quinolin-7-
ol,3-phenyl-2-thioxo-8-(trifluoromethyl)-2,3-dihydro-4H-[1,3]oxazino[5,6-c]quinolin-4-one and ethyl 8-(tri-
fluoromethyl)-2-methyl-4-oxo-4H-pyrano[3,2-c]quinolone 3-carboxylate,respectively. The structures of the syn-
thesized compounds were confirmed by elemental analysis and spectral data.
Keywords: isoxazoloquinoline, pyrazoloquinoline, pyranoquinoline, cytotoxic activity
DOI: 10.1134/S1070428020020219
INTRODUCTION
RESULTS AND DISCUSSION
Quinoline nucleus exist in many natural and synthetic
products [1] and has a wide range of biological activity
as antimalarial [2], antibacterial [3], antifungal [4],
antimicrobial [5], inhibiting agents [6] and anticancer
agents [7].
Inthepresentworkwesynthesizednovelderivativesof
ethyl 4-hydroxy-7-(trifluoromethyl)-quinoline-3-carbo-
xylate (1), where the 3- and 4-substitents were modified
throughdifferentreactionssothattheanticancereffectofthe
resulting compounds was enhanced compared to the
startingcompound.Atthesametime,weaimedthatthatthe
newly formed moiety in the synthesized quinoline deri-
vatives, regardless of its position, contained the same
structural fragment as Tivozinib, Ki 8751, or Lenvatinib
(Scheme 1).
Because cancer is one of the most health problems
all over the world causing death [8], researches being
accomplished to afford potential safe anticancer agents.
In the present work, quinoline ring was selected as
an essential core due to its well-known antiproliferative
activitythroughinhibitionofdifferentenzymesincluding
topoisomerase [9], thymidylate synthase, telomeras
[10] and different protein kinases [11]. VEGF-TKIs
are valuable cancer therapy [12] that permit promising
strategy for controlling different tumors [13]. Varied
drugs containing quinoline nucleus as Tivozinib [14],
Ki8751 [15], Lenvatinib [16] were recently approved
for the therapy of various solid tumors.
Compound 1 exists as an equilibrium mixture of
three tautomers, with the abundance of each tautomer
depending on the nature of the solvent (Scheme 2). In
DMF, the most abundant form is enol 1b, as evidenced
by the presence in its IR spectrum of absorption bands
at 3121, 1690, and 1617 cm–1 assignable respectively
307

308
REGAL et al.
Scheme 1.
H
N
H
N
H
H
N
H
N
H
N
N
O
F
O
O
N
F
F
O
O
Cl
O
N
O
O
O
N
Cl
O
O
O
O
H2N
N
Lenvatinib
OH
Tivozanib
Ki 8751
O
NH
NH
HN
O
O
O
O
N
NH2
H
F3C
N
8
F3C
N
9
F3C
N
7
to the OH group, chelated C=O group, and C=N
bond.
13.53 and 15.01 ppm from two enolic OH groups and a
one-proton singlet signal at 3.88 ppm from the methane
proton. The mass spectrum of the product showed a
parent peak at m/z 315 (Scheme 3).
The predominance of tautomer 1b was also proved
by its chemical behavior: as a nucleophile due to the
presence of the OH group or as an electrophile due to
the presence of the ester group.
Attempted acylation of compound 1 with acetyl
chloride in a 10% alcoholic sodium hydroxide at
room temperature under stirring involved acylation
of the nitrogen atom with hydrolysis of the ester
group to form the corresponding acid derivative 4 and a
known quinolone-3-carboxylic acid 5 (mp 259–260°C,
Scheme 4).
The reaction of 4-hydroxyquinoline derivative 1
with chloroacetyl chloride under reflux for 12 h in the
presence of pyridine as a base catalyst afforded acylation
product 2. The structure of the latter was confirmed by
the observation in its IR spectrum of absorption bands at
1720 and 1693 cm–1 from the two ester groups, as well
as by the presence in the 1H NMR spectrum of a singlet
at 2.73 ppm from the CH2Cl methylene protons together
with a quartet at 4.25 ppm and a triplet at 1.43 ppm for the
ester ethyl group in the. At the same time, refluxing the
same reactants for 24 h under the same conditions gave a
mixture of stereo isomeric condensation products 3a–3c,
which was confirmed by spectral data. The IR spectrum
showed an absorption band at 3450 cm–1 assignable
to enolic OH group, as well as bands at 1717 and
1680 cm–1 from the ester and ketone carbonyls,
respectively. Evidence for the formation of the three
The structure of 1-acetyl-7-trifluoromethyl-4-oxo-
1H-quinoline 3-carboxylic acid (4) was proved by its
IR spectrum, which shows a broad absorption band at
3675–2570 cm–1 from the carboxylic OH group, as well
as three absorption bands at 1692, 1685, and 1675 cm–1
from the three carbonyl groups. The 1H NMR spectrum
contains a singlet signal at 14.45 ppm from the COOH
proton and a singlet signal at 2.13 ppm from the acetyl
CH3 protons. The mass spectrum displayed a peak at m/z
301 attributed to [M + 2].
The ester group of quinoline derivative 1 was
allowed to react with nucleophilic reagents, such as
urea, thiourea, hydrazine hydrate, hydroxylamine and/
or o-phenylenediamine. The reactions of 1 with urea
1
isomers was also provided by the presence in the H
NMR spectrum of two one-proton singlet signals at
Scheme 2.
H
O
O
O
O
O
COOEt
OEt
OEt
N
F3C
F3C
N
N
F3C
H
1a
1b
1c
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REACTIVITY AND ANTICANCER ASSESSMENT OF 4-HYDROXYQUINOLINE DERIVATIVES
309
Scheme 3.
O
Cl
O
O
CO2C2H5
DMF/Pyridine
Cl
1
+
Cl
Reflux, 12 h
N
F3C
O
DMF/Pyridine,
reflux, 48 h
2
O
OH
Cl
Cl
Cl
O
O
O
N
O
O
OH
N
F3C
F3C
N
F3C
3a
3b
3c
Scheme 4.
O
O
O
O
O
H3C
Cl
OH
OH
1
+
EtOH/NaOH(10%)
N
F3C
N
H
F3C
COCH3
4
5
and/or thiourea in the presence of sodium ethoxide as
a base catalyst under reflux gave carboxamide 6 and
thiocarboxamide 7, respectively (Scheme 5).
that was assured by the appearance of an [M + 1]+ion
peak at m/z 316.
Pyrazoloquinoline8,isoxazoloquinoline9,anddiaze-
pinoquinoline 10 were obtained by heating quinoline
derivative 1 with hydrazine hydrate in DMF, hydroxy-
lamine hydrochloride in a mixture of pyridine and DMF,
and o-phenylenediamine in DMF, respectively. The
reactions involved initial attack of nitrogen nucleophile
on the ester group and the subsequent cyclo condensation
reaction (Scheme 6).
The structure of urea derivative 6 was confirmed
by the presence of two absorption peaks at 1685 and
1656 cm–1 from the two amide carbonyl groups in the
IR spectrum and a two-proton singlet at 1.86 ppm from
the NH2 group and a one-proton singlet at 11.35 ppm
from the OH group in the 1H NMR spectrum. The mass
spectrum showed an [M – NH2]+ ion peak at m/z 283.
The formation of thiourea derivative 7 was confirmed
by the presence in the IR spectrum of NH, NH2, and
OH absorption bands at 3368, 3273, and 3167 cm–1,
respectively, and only one amide carbonyl absorption
band at 1665 cm–1; as well as by the presence of an and
The IR spectra of compounds 8–10 showed bands of
the ester carbonyl group but contained bands at 1673,
1679, and 1664 cm–1, respectively, corresponding to the
amide carbonyl, as well as the N–H absorption bands at
3326, 3243, and 3240 cm–1, respectively. The 1H NMR
Scheme 5.
S
O
OH
O
O
OH
O
S
H2N
NH2
H2N
EtONa
NH2
N
NH2
N
NH2
1
H
H
EtONa
F3C
N
F3C
N
7
6
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310
REGAL et al.
Scheme 6.
NH
NH
HN
O
O
O
.
H2N NH2
DMF
NH2OH HCl
1
pyridine/DMF
F3C
N
F3C
N
NH2
NH2
9
8
DMF,
reflux, 10 h
NH
N
HO
N
CF3
10
spectrum of compound 8 displayed two singlet signals
at 10.57 and 13.25 ppm from the two NH protons, while
in the spectrum of isoxazoloquinoline derivative 9 only
one NH signal was observed as a singlet at 14.88 ppm.
The 1H NMR spectrum of benzodiazepine derivative 10
contained two singlets at 12.54 (broad) and 15.2 ppm,
corresponding to the NH and OH protons, respectively.
The mass spectrum showed a parent ion peak at m/z 329.
product 5 (Scheme 8). The structure of compound 12
was confirmed by the presence in its IR spectrum of two
absorption bands at 1715 and 1695 cm–1 corresponding
to the ester and ketone carbonyls, respectively, and
the absence of bands assignable to the OH and/or NH
1
groups. Further evidence was obtained from the H
NMR spectrum, which showed a three-proton triplet at
1.42 ppm and a two-proton quarter at 3.95 ppm from
the ester ethyl group, as well as a three-proton singlet at
2.31 ppm assignable to the C=C–CH3 group.
Oxazinoquinoline derivative 11 was obtained by
the nucleophilic addition of the OH group of quinoline
derivative 1 to phenyl isothiocyanate in boiling DMF
followed by cyclization with the elimination of ethanol.
The structure of compound 11 was supported by the
IR spectrum, which showed an absorption band of
amide carbonyl at 1667 cm–1 and no absorption bands
Antitumor activity testing. All the synthesized
quinoline derivatives were tested for their antitumor
activity against three human tumor cell lines:
hepatocellular carcinoma (HePG-2), colorectal carci-
noma (HCT-116), and mammary gland (MCF-7).
Doxorubicin was used as a standard anticancer drug
for comparison. The results are presented in the table 1.
Compound 8 exhibited the highest activity (very
strong) against the three test cell lines. Compound
9 showed a high activity against MCF-7 and a strong
activity against HePG2 and HCT-116. Compound 11
demonstrated a strong cytotoxic activity against the
1
of the OH and/or NH group. The H NMR displayed a
multiplet at 7.12–7.53 ppm corresponding to new five
aromatic protons in addition to four quinoline nucleus
protons (Scheme 7).
The reaction of quinoline derivative 1 with ethyl
acetoacetate in the presence of H2SO4 as an acid
catalyst gave pyranoquinoline 12 and hydrolysis
Scheme 7.
S
Ph
O
N
Ph–N=C=S/DMF
1
Reflux, 12 h
O
F3C
N
11
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REACTIVITY AND ANTICANCER ASSESSMENT OF 4-HYDROXYQUINOLINE DERIVATIVES
311
Scheme 8.
CH3
CO2Et
OH
N
O
O
O
COOH
O
O
+
1
DMF/H2SO4
Reflux, 24 h
F3C
F3C
N
12
5
Ethyl 4-(2-chloroacetoxy)-7-(trifluoromethyl) qui-
noline-3-carboxylate (2). Amixture of quinoline ester 1
(1.4 g, 0.005 mol) and chloroacetyl chloride (0.62 g,
0.0055 mol) was refluxed in DMF (20 mL) in the
presence of pyridine (2 mL) for 12 h. After completion
of the reaction (by TLC) the reaction mixture poured
into ice water and neutralized after cooling with dilute
HCl. The solid material that formed was collected by
filtration, dried, and crystallized from methanol to obtain
0.6 g (35%) of compound 2 as pale yellow crystals, mp
161–163°C. IR spectrum, ν, cm–1: 2991 w and 2910 w
(CHaliph), 1720 s (C=O of COCH2Cl), 1693 s (C=O ethyl
ester), 1638 s (C=N). 1H NMR spectrum, δ, ppm: 1.43 t
(3H, CH3), 2.73 s (2H, CH2), 4.25 q (2H, CH2), 7.72 d
(1H, ArH, J 7.6 Hz), 8.01 s (1H, CH2), 8.35 d (1H, ArH,
J 8.8 Hz), 8.70 s (1H, ArH). Found, %: C 49.70; H 2.98;
N 3.72. C15H11ClF3NO4. Calculated, %: C 49.81; H 3.07;
N 3. 87. M 376.73.
HCT-116 and MCF-7 cell lines and a moderate activity
against HePG2. Compound 7 was highly active against
HePG2 and MCF-7 and moderately active against
HCT-116. Compounds 4 and 6 showed a moderate
activity against the three cell lines, while 2 and 12
showed a weak activity against the three cell lines. The
latter two compounds proved to be even less active than
the starting quinoline derivative 1.
EXPERIMENTAL
The melting points were measured on a Gallen kamp
electric melting point apparatus and were uncorrected.
The IR spectra were recorded on a Pye Unicam SP-3-
1
300 spectrophotometer in KBr. The H NMR spectra
were run on a Varian Mercury VX-300 and Bruker
Avance III 400 MHz NMR spectrometers in DMSO-d6
using TMS as internal standard. The mass spectra were
recorded on a Shimadzu GCMS-QP-1000EX instrument
at 70 eV. All chemical reactions were monitored by TLC
on Silica Gel 60 F254 plates (Merck) in ethyl acetate-
petroleum ether as solvent.
3-Chloro-8-(trifluoromethyl)-2H-pyrano[3,2-c]-
quinoline-2,4(3H)-dione (3).Amixture of the quinoline
ester 1 (1.4 g, 0.005 mol) chloroacetyl chloride (0.62 g,
Table 1. Cytotoxic activity of the synthesized quinoline derivatives against human tumor cells
In vitro cytotoxic IC50, μMa
Compound no.
HePG2
HCT-116
5.23±0.3
MCF-7
Doxorubicin
4.50±0.2
4.17±0.2
35.20±2.2
74.18±3.7
21.13±1.7
29.27±2.0
13.79±1.2
6.48±0.5
8.13±0.9
18.71±1.5
46.97±2.8
1
2
48.55±3.1
82.78±4.7
33.02±2.3
39.72±2.8
18.04±1.4
7.48±0.6
51.27±3.0
67.48±3.5
28.12±1.9
31.95±2.1
25.23±1.7
9.79±0.8
4
6
7
8
9
11.36±1.1
26.79±1.9
63.45±3.6
19.30±1.5
12.86±1.1
72.03±4.2
11
12
a IC50, μM: 1–10 (very strong); 11–20 (strong); 21–50 (moderate); 51–100 (weak); and > 100 (noncytotoxic).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 56 No. 2 2020

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REGAL et al.
0.0055 mol) was refluxed in DMF (50 mL) in the
presence of pyridine (2 mL) for 48 h. After completion
of the reaction (by TLC), the reaction mixture poured
over ice-water mixture after cooling and neutralized
by dil. HCl. The formed solid collected by filtration,
dried and crystallize from ethanol to give 1 g (65%)
of compound 3 as white crystals; mp 194–196°C. IR
spectrum, ν, cm–1: 3450 s (OH), 2940 w (CH, aliph.),
1717s(C=Oester), 1680s(C=Oketonic). 1HNMRspec-
trum, δ, ppm: 2.73 s (1H, CH–Cl), 3.88 s (1H, Cl–CH),
7.81 d (1H, ArH, J 9.6 Hz), 8.17 s (1H, ArH), 8.41 d
(1H, ArH, J 8.0 Hz), 9.55 s (1H, ArH), 13.53 s (1H, OH),
15.01 s (1H, OH enolic). Mass spectrum, m/z (Irel, %):
315 (2), 301 (18), 285 (42), 256 (60), 242 (100), 239
(47), 81 (26), 69 (60). Found, %: C 49.32; H 1.52; N
4.28. C13H5ClF3NO3. Calculated, %: C 49.47; H 1.60;
N 4.44. M 315.63.
8.79 s (1H, ArH), 11.35 s (1H, OH). Mass spectrum,
m/z (Irel, %): 283 [M – NH2], 270 (17), 240 (18), 239
(100), 169 (10). Found, %: C 48.1; H 2.57; N 14.10.
C12H8N3O2F3S. Calculated, %: C 48.17; H 2.69; N
14.04. M 299.21.
1-[4-Oxo-7-(trifluoromethyl)-3,4-dihydroquino-
line-3-carbonyl)]thiourea (7). Yield 0.6 g (40%),
yellow crystals, mp 216–218°C (methanol). IR spec-
trum, ν, cm–1: 3368 w, 3273 s (NH2), 3167 s (NH), 1685 s
1
(C=O ketone) and 1656 s (C=O amide). H NMR
spectrum, δ, ppm: 1.86 s (2H, NH2), 7.49 d (1H, ArH),
8.11 s (1H, ArH), 8.47 d (1H, ArH), 8.91 s (1H, ArH),
11.35 s (1H, OH). Mass spectrum, m/z (Irel, %): 316 (97)
[M + 1], 257 (42), 255 (85), 159 (12), 127 (20), 63 (100).
Found, %: C 46.01; H 2.67; N 13.28. C12H8N3O2F3S.
Calculated, %: C 45.72; H 2.56; N 13.33. M 315.27.
7-(Trifluoromethyl)-1,2-dihydropyrazolo[4,3-c]-
quinolin-3-one (8). A mixture of compound 1 (1.4 g,
0.005 mol) and hydrazine hydrate 98% (2 mL, 0.06 mol)
in DMF (30 mL) was refluxed for 72 h. After
completion (by TLC) the reaction mixture poured over
ice/water mixture, the solid that was filtered off, dried
and crystallize from methanol to give 0.6 g (52%) of
compound 8 as white crystals; mp 221–223°C. IR
spectrum, ν, cm–1: 3326 m (NH), 3243 s (NH), 1673 s
(C=O). 1H NMR spectrum, δ, ppm: 7.75 d (1H, ArH, J
9.2 Hz), 8.08 s (1H, ArH), 8.45 d (1H, ArH, J 8.8 Hz),
8.88 s (1H, ArH), 10.57 s (1H, NH), 13.25 s (1H, NH).
Mass spectrum, m/z (Irel, %): 252 (3) [M – 1], 239.89
(100), 211 (16), 183.91 (20), 163.85 (88), 136.89 (9).
Found, %: C 51.98; H 2.57; N 16.48. C11H6F3N3O.
Calculated, %: C 52.18; H 2.39; N 16.60. M 253.18.
1-Acetyl-4-oxo-7-(trifluoromethyl)-1,4-dihydro-
quinoline-3-carboxylic acid (4). In alcoholic sodium
hydroxide (30 mL-10%), was stirred with A mixture
of quinoline derivative 1 (1.4 g, 0.005 mol) and acetyl
chloride (0.4 g, 0.005 mol) in 10% alcoholic NaOH
(30 mL) was stirred at temperature 40–45°C for 6 h.
After completion of the reaction (by TLC), the reaction
mixture poured into ice water and neutralized with
dilute HCl. The formed solid precipitated was filtered,
dried and crystallize from ethanol to give 0.8 g (53%)
of compound 4 as white crystals; mp 157–159°C. IR
spectrum, ν, cm–1: 3675–2560 br.s (OH), 1692 s (C=O
ketone), 1675s(C=Oamide). 1HNMRspectrum, δ, ppm:
2.24 s (3H, CH3), 7.47 d (1H, ArH), 8.01 s (1H, ArH),
8.37 d (1H, ArH), 8.79 s (1H, ArH), 14.45 s (1H, OH).
Mass spectrum, m/z (Irel, %): 301 (86) [M + 2], 282 (50),
249 (14), 77 (17), 57 (45), 43 (100). Found, %: C 51.98;
H 2.61; N 4.55. C13H8F3NO4. Calculated, %: C 52.19;
H 2.70; N 4.68. M 299.2.
7-(Trifluoromethyl)isoxazolo[4,5-c]quinolin-
3(2H)–one (9). Pyridine (0.5 mL) was added to a
mixture of quinoline derivative 1 (1.4 g, 0.005 mol)
and hydroxylamine hydrochloride (0.34 g, 0.005 mol)
in DMF (50 mL). The reaction mixture was refluxed
for 48 h. After completion of the reaction (by TLC)
and cooling, the reaction mixture was poured into ice
water and neutralized with dilute HCl. The formed solid
was filtered off and crystallized from ethanol to obtain
0.7 g (56%) of compound 9 as yellow crystals, mp
195–197°C. IR spectrum, ν, cm–1: 1679 s (C=O), 1614 s
(C=N). 1H NMR spectrum, δ, ppm: 7.86 d (1H, ArH, J
8.0 Hz), 8.15 s (1H, ArH), 8.45 d (1H, ArH, J 8.8 Hz),
9.04 s (1H, ArH), 14.88 s (1H, NH). Mass spectrum, m/z
(Irel, %): 238 (4), 103 (10), 101 (25), 88 (87), 60 (100),
42(52).Found,%:C51.82;H1.89;N10.98.C11H5F3N2O2.
Calculated, %: C 51.98; H 1.98; N 11.02. M 254.16.
Synthesisofcompounds6and7( generalprocedure).
A mixture of quinoline derivative 1 (1.4 g, 0.005 mol)
and urea (3.4 g, 0.055 mol) or thiourea (4.2 g, 0.055 mol)
was refluxed in ethanol (50 mL) in the presence of
sodium ethoxide (0.5 g) for 5 h. After completion of
the reaction (by TLC), the reaction mixture poured into
ice water and neutralized with dilute HCl. The formed
solid product was collected by filtration, dried, and
crystallized from appropriate solvent.
1-[4-Oxo-7-(trifluoromethyl)-3,4-dihydroquino-
line-3-carbonyl)]urea (6). Yield 0.5 g (36%), pale
yellowcrystals, mp181–183°C(methanol). IRspectrum,
ν, cm–1: 3476 s, 3420 w (NH2), 3137 (NH), 1697 s (C=O
1
ketone) and 1656 s (C=O amide). H NMR spectrum,
3-(Trifluoromethyl)-13H-benzo[2,3][1,4]diaze-
pino[6,5-c]quinolin-7-ol (10).Amixture of o-phenylene
diamine (0.86 g, 0.005 mol) and quinoline ester 1 (1.4 g,
δ, ppm: 1.86 s (3H, NH2, NH), 7.48 d (1H, ArH, J
8.2 Hz), 8.0 s (1H, ArH), 8.37 d (1H, ArH, J 8.8 Hz),
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REACTIVITY AND ANTICANCER ASSESSMENT OF 4-HYDROXYQUINOLINE DERIVATIVES
313
0.005 mol) was refluxed for 10 h in DMF (50 mL).
After completion of the reaction (by TLC) the reaction
mixture was cooled and poured over ice-water mixture.
The precipitated solid formed was filtered off, dried and
crystallize from methanol–benzene mixture (2 : 1) to
give 0.4 g (26%) of compound 10 as brown crystals; mp
279–281°C. IR spectrum, ν, cm–1: 3420 s (OH), 3240 m
(NH), 1664 s (C=O), 1621 s (C=N). 1H NMR spectrum,
δ, ppm: 7.12–7.62 m (4H, ArH), 7.72 d (1H, ArH),
8.01 s (1H, ArH), 8.35 d (1H, ArH), 8.73 s (1H, ArH),
12.54 br.s (1H, NH), 15.2 s (1H, OH). Mass spectrum,
m/z (Irel, %): 329 (9), 314 (12), 301 (12), 297 (16), 93
(100), 76 (11). Found, %: C 61.85; H 2.98; N 12.61.
C17H10F3N3O. Calculated, %: C 62.01; H 3.06; 17.31;
N 12.76. M 329.28.
N 3.99. C17H12NO4F3. Calculated, %: C 58.13; H 3.44;
N 3.99. M 381.12.
4-Hydroxy-7-(trifluoromethyl)-quinoline-3-car-
boxylic acid (5). IR spectrum, ν, cm–1: 3550–2500 br.s
1
(OH), 1683 s (C=O), 1616 s (C=N). H NMR spec-
trum, δ, ppm: 7.58 d (1H, ArH, J 8.4 Hz), 8.21 s (1H,
ArH), 8.53 d (1H, ArH), 9.10 s (1H, OH enolic),
14.88 s (1H, COOH). Found, %: C 51.17; H 2.22; N
5.36. C11H6F3NO3. Calculated, %: C 51.38; H 2.35. M
257.17.
MTT assay. The HePG-2 hepatocellular carcinoma,
HCT-116 colorectal carcinoma, and MCF-7 mammary
gland cancer cell lines were obtained from the ATCC
via the Egyptian Holding Company for Biological
Products and Vaccines (VACSERA), Cairo, Egypt. The
RPMI-1640 medium, MTT, and DMSO were purchased
from Sigma, and fetal bovine serum was obtained from
GIBCO.
3-Phenyl-2-thioxo-8-(trifluoromethyl)-2,3-di-
hydro-4H-[1,3]oxazino[5,6-c]quinolin-4-one
(11).
Quinoline derivative 1 (1.4 g, 0.005 mol) was heated
underrefluxwithphenylisothiocyanate(0.7g,0.005mol)
in DMF (50 mL) for 12 h. After completion (by TLC),
the reaction mixture was cooled, poured over ice-water
mixture to give the solid Product that was filtered off,
dried and then crystallize from ethanol to give 1 g (56%)
of compound 11 as yellow crystals of mp 172–174°C.
IR spectrum, ν, cm–1: 1667 s (C=O), 1630 s (C=N).
1H NMR spectrum, δ, ppm: 7.12–7.53 m (5H, ArH),
7.87 d (1H, ArH), 8.19 s (1H, ArH), 8.36 d (1H, ArH),
8.78 s (1H, ArH). Found, %: C 57.68; H 2.38; N 7.35.
C18H9F3N2O2S. Calculated, %: C 57.75; H 2.42; N 7.48.
M 390.83.
Cells were cultured in RPMI-1640 medium with
10% fetal bovine serum, 100 IU/mL Penicillin, and
100 μg/mLStreptomycin at 37°C in a 5% CO2 incubator.
The cell lines were seeded in a 96-well plate at a density
of 1.0 × 104 cells/well at 37°C for 48 h under 5% CO2
and then treated with different concentration of the test
compounds. After 24-h incubation, 20 μL of a 5 mg/mL
MTT solution was added, and incubation was continued
for an additional 4 h. The purple formazan crystals that
formedweredissolvedin100μLofDMSO. Colorimetric
assay was performed by measuring absorbance of 570
nm on a Bio TekEXL 800 plate reader. The percentage
relative cell viability was calculated as (A570 of treated
sample/A570 of untreated sample) × 100.
Reaction of compound 1with ethyl acetoacetate.
Sulfuric acid (5 mL, 75%) was added to a mixture of
compound 1 (1.4 g, 0.005 mol) and ethyl acetoacetate
(7.2 g, 0.055 mol) in DMF (50 mL). The reaction
mixture was heated under reflux on a water bath for 12 h,
after completion (by TLC), the reaction mixture was
cooled, the formed solid was separated and washed by
Na2CO3 solution (50 mL, 20%) then filtered, washed
by water, dried and crystallize from ethanol to give 1 g
(65%) of compound 12 as brown crystals of mp above
300°C. The filtrate of carbonate solution was acidified
by dil. HCl, separated and crystallized to give 0.2 g
(18%) of compound 5 as white crystals; mp 259–260°C
(Sigma-Aldrich, Pub. Chem. substance ID 24851573,
mp 259–260°C).
CONCLUSIONS
The moderate cytotoxicity of the starting 4-hydroxy-
3-carboethoxyquinoline derivative 1 was increased
by converting to urea and thiourea derivative, where
the former become of strong toxicity to two cell lines
(HePG2 and MCV-7), moderate for HCT-116, while the
latter become of moderate toxicity for all the three cell
lines as N-acetyl quinoline derivative 4.
The cytotoxicity was again increased through
cyclization around the positions 3- and 4- to result
in very strong behavior for the dihydropyrazolone
derivative 8 with respect to all the 3 cell lines, still of
strong effect for the isoxazolone derivative 9. The cyclic
oxazine derivative 11 shows strong toxicity to HCT-116
and MCV-7 and moderate effect for HePG2cell, whereas
oxopyrano derivative 12 was moderate for MCF-7 and
weak for both HePG2 and HCT-116. However, the
toxicity behavior of compound 1 becomes very week
by alkylating the hydroxyl group at position C4 to give
chloroacetoxy derivative 2.
Ethyl
8-(trifluoromethyl)-2-methyl-4-oxo-4H-
pyrano[3,2-c]quinolone 3-carboxylate (12). IR
spectrum, ν, cm–1: 2975, 2941 w (CH aliph.), 1715 s
(C=O ester), 1695 s (C=O ketone). 1H NMR spectrum,
δ, ppm: 1.42 t (3H, CH3), 2.72 s (3H, CH3), 3.95 q (2H,
CH2), 7.87 d (1H, ArH), 8.19 s (1H, ArH), 8.48 d (1H,
ArH), 9.07 s (1H, ArH). Found, %: C 58.11; H 3.38;
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314
REGAL et al.
https://doi.org/10.1021/jo01079a027
ACKNOWLEDGMENTS
8. Jemal, A., Bray, F., Center, M. M., Ferly, J., Ward, E.,
and Forman, D., CA Cancer J. Clin., 2011, vol. 61, p. 69.
https://doi.org/10.3322/caac.20107. Epub 2011 Feb 4.
9. Nitiss, J.L., Nat. Rev. Cancer, 2009, vol. 9, p. 338.
https://doi.org/10.1038/nrc2607
All spectral measurements were carried out at the NMR
laboratory of the Cairo University, and the NMR laboratory
of the Faculty of Pharmacy, Ain Shams University, Egypt.
The elemental analyses were obtained at the Central Lab,
Cairo University, the Egypt Ministry of Defense Chemical
Laboratories and the Micro Analytical Center, Ain Shams
University. The authors would like to extend their sincere
appreciation to all these institutions for cooperation in the
present research.
10. Zhou, J.L., Lu, Y.J., Ou, T.M., Zhou, J.M., Huang, Z.S.,
Zhu, X.F., Du, C.J., Bu, X.Z., Ma, L., Gu, Q., Li, Y.M.,
and Chan, A.S., J. Med. Chem., 2005, vol. 48, p. 7315.
https://doi.org/10.1021/jm050041b
CONFLICT OF INTEREST
The authors declare no conflict of interest.
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