Design, Synthesis, and Anticancer Activity of 1,2,3-Triazole Likned Thiazole-1,2-isoxazole Derivatives

Article abstract of DOI:10.1134/S1070363219120314

A series of novel 1,2,3-triazole linked thiazole-1,2-isoxazole derivatives has been designed, synthesized and characterized by ¹H and ¹³C NMR, and mass spectral analysis. The compounds have been tested for their anticancer activity t

Full text of DOI:10.1134/S1070363219120314

ISSN 1070-3632, Russian Journal of General Chemistry, 2019, Vol. 89, No. 12, pp. 2522–2527. © Pleiades Publishing, Ltd., 2019.
Design, Synthesis, and Anticancer Activity
of 1,2,3-Triazole Likned Thiazole-1,2-isoxazole Derivatives
T. Yakanthama, R. Sreenivasulub, G. Alluraiahc, M. B. Tejd, and R. Ramesh Rajua,*
a Department of Chemistry, Acharya Nagarjuna University, Nagarjuna Nagar, Andhra Pradesh, 522510 India
b Department of Chemistry, University College of Engineering (Autonomous), Jawaharlal Nehru Technological University,
Kakinada, Andhra Pradesh, 533003 India
c Department of Chemistry, S V Arts and Science College, Giddalur, Andhra Pradesh, 523357 India
d Department of Pharmacy, Sri Ramachandra Institute of Higher Education and Research,
Porur, Chennai, 600116, Tamil Nadu, India
*e-mail: rrraju1@gmail.com
Received June 12, 2019; revised December 17, 2019; accepted December 22, 2019
Abstract—A series of novel 1,2,3-triazole linked thiazole-1,2-isoxazole derivatives has been designed, synthe-
1
sized and characterized by H and 13C NMR, and mass spectral analysis. The compounds have been tested for
their anticancer activity towards MCF-7 (breast cancer), A549 (lung cancer), Colo-205 (colon cancer), and A2780
(ovarian cancer) by using the MTT method using etoposide as the reference. Most of the tested compounds dem-
onstrate good to moderate activity against all cell lines. The compounds 14b, 14e, 14g, and 14h are characterized
by inhibitory activity stronger than that of etoposide.
Keywords: triazole, thiazole, isoxazole, MTT assay, anticancer activity
DOI: 10.1134/S1070363219120314
INTRODUCTION
linked thiazole-1,2-isoxazole derivatives 14a–14j and
characterized their structures by NMR and Mass spectral
data. The synthesized compounds were tested for anti-
cancer activity against a panel of human cancer cell lines.
Thiazoles are characterized by a wide variety of bio-
logical activities including antitumour [1], antioxidant [2],
antiviral [3], and many more. Thiazole makes a structural
block of an US-FDAapproved anticancer drug candidate
Dasatinib (1, see the figure), used for treatment of acute
lymphoblastic leukemia [4].
RESULTS AND DISCUSSION
The synthetic approach to 1,2,3-triazole linked
thiazole-1,2-isoxazole derivatives 14a–14j is outlined in
Scheme 1. Reaction of 2-bromo-1-(pyridin-4-yl)ethanone
hydrobromide (3) with ethyl thiocarbamoylformate (4)
gave ethyl 4-(pyridin-4-yl)thiazole-2-carboxylate (5).
Its following reduction in presence of DBAL-H afforded
the aldehyde 6. The Claisen-Schmidt condensation of
the intermediate 6 with 1-(4-nitrophenyl)ethanone (7) in
Similarly, 1,2,3-triazole derivatives exhibited nu-
merous biological properties including anticancer [5],
antifungal [6], antitubercular [7], and anti-HIV [8]. Tri-
azole cycle is a fragment of molecular structure of the
anticancer drug Carboxyamido (2, CAI) [9-11].
In view of the above as well as our recent studies [12],
we have designed and synthesized novel 1,2,3-triazole
(a)
Cl
(b)
O
Cl
N
O
HN
N
N
N
N
N
S
Cl
Cl
N
N
H2N
O
H
H2N
N
HO
2
1
Structures of Dasatinib (a) 1 and (b) CAI 2.
2522

DESIGN, SYNTHESIS, AND ANTICANCER ACTIVITY
2523
Scheme 1. Synthesis of the target 1,2,3-triazole linked thiazole-1,2-isoxazole derivatives.
O
O
O
H
N
N
S
S
O
S
O
EtOH, reflux,
4 h
Br
+
DIBAL-H, DCM
H2N
·HBr
N
N
ꢀ
78
qC, 1 h
O
4
6
N
5
3
O
EtOH, piperidine
reflux, 12 h
NO2
7
N
O
O
N
N
·
N
NH OH
HCl, IPA
2
N
NO2
S
pyridine, reflux, 6 h
9
S
8
NO2
Ethanol, room temperature,
12 h
Pd/C, H2
O
N3
HO
N
O
N
O
N
11
N
O
N
N
N3
EDCI, HOBt, DCM
room temperature,
12 h
NH2
S
10
N
S
H
12
CuI, THF,
room temperature, 16 h
R
ꢀ
13a 13j
R
N
N
N
O
O
N
N
N
N
S
H
14aꢀ14j
R = H (13a, 14a), 3,4,5-trimethoxy (13b, 14b), 3,5-dimethoxy (13c, 14c), 4-methoxy (13d, 14d),
4-chloro (13e, 14e), 4-bromo (13f, 14f), 4-nitro (13g, 14g), 3,5-dinitro (13h, 14h), 4-methyl (13i, 14i),
3,5-dimethyl (13j, 14j).
presence of piperidine base led to chalcone 8, which was
subjected to cyclization with hydroxyl amine hydrochlo-
ride in pyridine with formation of isoxazole intermediate
9. Reduction of compound 9 with Pd/C,H2 led to the
amino intermediate 10, further coupling of which with
2-azidoacetic acid 11 in presence of EDCI, HOBt af-
forded azide 12. Its following 1,3-dipolar cycloaddition
with various substituted aryl alkynes 13a–13j catalysed
by CuI gave the corresponding target products 14a–14j.
Biological tests. In vitro cytotoxicity. The newly pre-
pared compounds 14a–14j were tested in vitro against
four human cancer cell lines, including MCF-7 (breast
cancer),A549 (lung cancer), Colo-205 (colo cancer), and
A2780 (ovarian cancer) by employing the MTT method
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YAKANTHAM et al.
In vitro cytotoxicity (IC50, μM) of the newly synthesized compounds 14a–14ja
Compound
MCF-7
A549
Colo-205
A2780
14a
14b
2.66±1.87
1.55±0.83
3.17±2.13
4.56±2.88
1.66±0.19
8.11±4.67
0.83±0.018
0.083±0.005
9.61±5.44
16.4±4.33
2.11± 0.024
Not determined
1.95±0.32
2.88±1.23
0.38±0.063
2.11±1.22
Not determined
1.10±0.72
14c
2.43±1.64
Not determined
7.82±4.55
14d
10.3±6.45
12.9±6.11
14e
1.87±0.22
0.93±0.061
Not determined
0.11±0.045
0.014±0.002
18.5±7.12
1.34±0.89
14f
Not determined
0.19±0.093
0.01±0.009
2.04±1.09
5.77±3.17
14g
1.23±0.77
14h
0.77±0.017
Not determined
19.5±5.13
14i
14j
10.22±7.56
3.08± 0.135
6.32±3.90
Etoposide
0.13± 0.017
1.31± 0.27
a MCF-7: human breast cancer cell line. A549: human lung cancer cell line. Colo-205: human colon cancer cell line. A2780: human ovarian
cancer cell line.
(see the table). Etoposide was used as a reference. The
results indicated most of the tested products as highly to
moderately active against all considered cell lines with
IC50 values ranging from 0.01±0.009 to 19.5±5.13 μM,
IC50 values for etoposide ranged within 0.13± 0.017 to
3.08±0.135 μM. The compounds 14b, 14e, 14g, and 14h
demonstrated higher anticancer activity than etoposide
against four cell lines. The compound 14h exhibited the
most promising activity. According to the preliminary
structure-activity relationships (SARs) analysis of the
compounds, presence of the electron-donating group
(3,4,5-trimethoxyphenyl) (14b) resulted in its high an-
ticancer activity. Presence of two 3,5-dimethoxyphenyl
substituent in compound 14c induced its deceased activity
against four cell lines in comparison with 14b. Moving
along the same line, compound 14d with the 4-methoxy
substituent demonstrated even lower activity than 14c.
Replacement of the 4-methoxy group by 4-chloro (elec-
tron-withdrawing) substituent (14e) resulted in slightly
improved activity of the product against four cell lines.
The compound 14g containing the strong electron-
withdrawing group (4-nitro) on the phenyl ring was
characterized by excellent activity. The compound 14h
with 3,5-dinitro substituents on the phenyl ring exhibited
the highest anticancer activity against all cell lines.
ress was monitored by TLC, performed on silica gel (60
F-254) coated glass plates, and visualized under UV light
or by iodine indicator.
measured on a BRUKER NMR (300 MHz, 400 MHz)
spectrometer. ESI spectra were measured on a Micro
mass, Quattro LC using ESI+ software with capillary
voltage 3.98 kV and ESI mode positive ion trap detector.
Melting points were determined on an electro thermal
melting point apparatus, and are uncorrected.
1H and 13C NMR spectra were
Ethyl 4-(pyridin-4-yl)thiazole-2-carboxylate (5).
A mixture of 4-bromoacetylpyridine hydrobromide 3
(10 g, 0.0533 mmol) with ethyl thiooxamate 4 (4.4 mL,
0.0355 mmol) in ethanol (40 mL) was refluxed upon
stirring for 4 h. The reaction mixture was concentrated
under reduced pressure, and water was added to the
residue. pH Of the mixture was adjusted to 10 with 8 N
NaOH aqueous solution at 0°C and extracted with chlo-
roform. The organic layer was washed with brine, dried
over anhydrous MgSO4, filtered and concentrated under
reduced pressure to afford compound 5 as brown solid,
yield 75%. 1H NMR spectrum, δ, ppm: 1.48 t (3H), 4.53
q (2H), 7.85 d.d (2H, J = 4.4, 1.6 Hz), 7.98 s (1H), 8.71
d.d (2H, J = 4.4, 1.6 Hz). MS (ESI): m/z: 235 [M + H]+.
4-(Pyridin-4-yl)thiazole-2-carbaldehyde (6). To a
solution of ethyl 4-(pyridin-4-yl)thiazole-2-carboxylate 5
(7 g, 0.0299 mmol) in anhydrous THF (30 mL) was added
DIBAL-H (9.5 mL, 0.5M, in THF–hexane, 0.0478 mmol)
dropwise at –78°C, then the reaction mixture was stirred
at the same temperature for 1 h. The reaction mixture
was hydrolyzed with 1 N aq HCl (5 mL), and the prod-
EXPERIMENTAL
All chemicals and reagents were obtained from
Sigma–Aldrich and Lancaster (Alfa Aesar) companies,
and used without further purification. Reactions prog-
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DESIGN, SYNTHESIS, AND ANTICANCER ACTIVITY
2525
2-Azido-N-(4-{5-[4-(pyridin-4-yl)thiazol-2-yl]-
isoxazol-3-yl}phenyl)acetamide (12). Compounds 10
(3.8 g, 0.0119 mmol), EDCI (2.8 g, 0.0178 mmol) and
HOBt (911 mg, 0.00595 mmol) were dissolved in 20 mL
of anhydrous dichloromethane and stirred at 0oC for 1 h.
2-Azidoacetic acid (11) (1.1 mL, 0.0143 mmol) was then
added to the mixture and stirred at room temperature for
12 h. After completion of the reaction, the mixture was
washed with saturated sodium bicarbonate solution. The
organic layer was evaporated under reduced pressure to
afford pure compound 12, yield 81%. 1H NMR spectrum,
δ, ppm: 4.93 s (2H), 7.56 d (2H, J = 7.7 Hz), 7.65 s (1H),
7.87 d.d (2H, J = 4.7, 1.6 Hz), 8.10 s (1H), 8.15 d (2H,
J = 7.7 Hz), 8.77 d.d (2H, J = 4.7, 1.6 Hz), 12.23 br. s
(1H). MS (ESI): m/z: 404 [M + H]+.
uct was extracted with diethyl ether (10 mL). The ether
layer was dried over anhydrous magnesium sulphate to
afford the crude product which was purified by column
chromatography with ethyl acetate/hexane (2:8) to afford
pure compound 6, yield 89%. 1H NMR spectrum, δ, ppm:
7.96 d.d (2H, J = 4.5, 1.8 Hz), 8.10 s (1H), 8.80 d.d (2H,
J = 4.5, 1.8 Hz), 9.23 s (1H). MS (ESI): m/z: 191 [M + H]+.
(E)-1-(4-Nitrophenyl)-3-[4-(pyridin-4-yl)thiazol-
2-yl]prop-2-en-1-one (8). To 4-(pyridin-4-yl)thiazole-
2-carbaldehyde 6 (4.5 g, 0.0236 mmol) dissolved in
20 mL of ethanol, were added 4-nitroacetophenone 7
(3.9 g, 0.0236 mmol) and 3 drops of piperidine. The
reaction mixture was refluxed for 12 h. After completion
of reaction, cold water (20 mL) was added slowly. The
crystalline precipitate was filtered off and purified by
recrystallization from ethanol to afford pure compound
2-(4-Phenyl-1H-1,2,3-triazol-1-yl)-N-{4-(5-[4-
(pyridin-4-yl)thiazol-2-yl]isoxazol-3-yl)phenyl}acet-
amide (14a). Azide 12 (200 mg, 4.9 mmol) and 1-ethy-
nylbenzene (13a) (0.33 mL, 4.9 mmol) were dissolved
in anhydrous THF (20 mL), and CuI (466 mg, 5 mol %,
2.45 mmol) was added to it. The mixture was stirred
vigorously at room temperature for 16 h. Upon comple-
tion of the process (THF), the solvent was evaporated
in vacuum, and the crude product was re-dissolved in
ethyl acetate (3×30 mL). The organic phase was washed
with water and dried over with Na2SO4. After removal
of the solvent in vacuum, the crude product was purified
by column chromatography with ethyl acetate–hexane
(6 : 4) to obtained pure compound 14a. Yield 57%, mp
1
8, yield 84%. H NMR spectrum, δ, ppm: 7.66 d (2H,
J = 7.8 Hz), 7.86 d.d (2H, J = 4.7, 1.9 Hz), 7.90 d (1H,
J = 15.1 Hz), 7.95 d (1H, J = 15.1 Hz), 8.05 s (1H), 8.14 d
(2H, J = 7.8 Hz), 8.78 d.d (2H, J = 4.7, 1.9 Hz). MS (ESI):
m/z: 338 [M + H]+.
4-{2-[3-(4-Nitrophenyl)isoxazol-5-yl]thiazol-4-yl}-
pyridine (9). A mixture of compound 8 (6.3 g,
0.0187 mmol) with hydroxylamine hydrochloride (2 g,
0.0280 mmol) was dissolved in 20 mLof 2-propanol, then
2 mL of pyridine were added, and the reaction mixture
was refluxed upon stirring for 6 h.After completion of the
process (TLC), the solvent was evaporated under reduced
pressure. The precipitated product was washed with water
(3×20 mL), and the crude product was purified by column
chromatography with ethyl acetate/hexane (3 : 7) to afford
pure compound 9, yield 80%. 1H NMR spectrum, δ, ppm:
7.73 s (1H), 7.87 d.d (2H, J = 4.8, 1.7 Hz), 7.92 d (2H,
J = 8.1 Hz), 8.10 s (1H, thio), 8.23 d (2H, J = 8.1 Hz),
8.79 d.d (2H, J = 4.8, 1.7 Hz). MS (ESI): m/z: 351
[M + H]+.
1
244–246°C. H NMR spectrum, δ, ppm: 7.55–7.69 m
(6H), 7.76 d (2H, J = 8.2 Hz), 7.87 d.d (2H, J = 4.7,
1.6 Hz), 7.94 d (2H, J = 8.2 Hz), 8.10 s (1H), 8.34 s (1H),
8.76 d.d (2H, J = 4.7, 1.6 Hz), 12.28 br. s (1H). 13C NMR
spectrum, δ, ppm: 52.5, 104.6, 116.4, 121.5, 122.3, 123.5,
126.8, 128.3, 128.7, 129.5, 129.8, 131.4, 139.2, 140.4,
142.3, 143.6, 150.5, 152.4, 159.7, 160.5, 170.5. MS (ESI):
m/z: 506 [M + H]+.
4-{5-[4-(Pyridin-4-yl)thiazol-2-yl]isoxazol-3-yl}-
benzenamine (10). To a solution of compound 9 (5
g, 0.0143 mmol) in 15 mL of ethanol were added 200
mg of 10% palladium on activated carbon. The reac-
tion mixture was stirred at room temperature for 12 h
under the atmosphere of hydrogen, then filtered, and the
solvent was evaporated. The crude product was purified
by column chromatography with ethyl acetate–hexane
(6 : 4) to obtain pure compound 10, yield 89%. 1H NMR
spectrum, δ, ppm: 6.92 br. s (2H), 7.38 d (2H, J = 7.5 Hz),
7.60 s (1H), 7.85 d.d (2H, J = 4.6, 1.5 Hz), 7.89 d (2H, J =
7.5 Hz), 8.08 s (1H, thio), 8.75 d.d (2H, J = 4.6, 1.5 Hz).
MS (ESI): m/z: 321 [M + H]+.
The compounds 14b–14j were synthesized according
to the above method presented for 14a from the corre-
sponding intermediates 13b–13j.
2-[4-(3,4,5-Trimethoxyphenyl)-1H-1,2,3-triazol-1-
yl]-N-(4-{5-[4-(pyridin-4-yl)thiazol-2-yl]isoxazol-3-yl}-
phenyl)acetamide (14b). Yield 45%, mp 276-278oC. 1H
NMR spectrum, δ, ppm: 3.89 s (3H), 3.92 s (6H), 5.03 s
(2H), 7.42 s (2H), 7.68 s (1H), 7.75 d (2H, J = 8.05 Hz),
7.88 d.d (2H, J = 4.8, 1.6 Hz), 7.92 d (2H, J = 8.05 Hz),
8.11 s (1H), 8.32 s (1H), 8.75 d.d (2H, J = 4.8, 1.6 Hz),
12.26 br. s (1H). 13C NMR spectrum, δ, ppm: 52.4, 57.8,
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YAKANTHAM et al.
2-[4-(4-Nitrophenyl)-1H-1,2,3-triazol-1-yl]-N-(4-
{5-[4-(pyridin-4-yl)thiazol-2-yl]isoxazol-3-yl}phenyl)-
acetamide (14g). Yield 70%, mp 310–312°C. 1H NMR
spectrum, δ, ppm: 5.32 s (2H), 7.48 d (2H, J = 7.8 Hz),
7.69 s (1H), 7.74 d (2H, J = 8.12 Hz), 7.88 d.d (2H, J =
4.8, 1.6 Hz), 7.93 d (2H, J = 8.12 Hz), 8.11 s (1H), 8.37
s (1H), 8.54 d (2H, J = 7.8 Hz), 8.77 d.d (2H, J = 4.8, 1.6
Hz), 12.41 br. s (1H). 13C NMR spectrum, δ, ppm: 52.7,
104.7, 118.5, 121.5, 122.7, 123.8, 126.8, 129.5, 130.2,
131.7, 135.7, 139.6, 140.2, 142.5, 143.2, 147.8, 159.2,
152.8, 159.6, 160.5, 171.7. MS (ESI): m/z: 551 [M + H]+.
61.6, 104.5, 110.5, 116.7, 121.4, 122.7, 123.6, 127.6,
128.3, 129.4, 139.2, 140.3, 142.6, 144.9, 145.7, 150.3,
152.4, 155.6, 159.3, 160.4, 170.6. MS (ESI): m/z: 596
[M + H]+.
2-[4-(3,5-Dimethoxyphenyl)-1H-1,2,3-triazol-1-yl]-
N-(4-{5-[4-(pyridin-4-yl)thiazol-2-yl]isoxazol-3-yl}-
phenyl)acetamide (14c). Yield 53%, mp 288–290°C. 1H
NMR spectrum, δ, ppm: 3.78 s (6H), 4.98 s (2H), 6.89 s
(1H), 7.33 s (2H), 7.67 s (1H), 7.72 d (2H, J = 8.08 Hz),
7.88 d.d (2H, J = 4.8, 1.6 Hz), 7.91 d (2H, J = 8.08 Hz),
8.11 s (1H), 8.33 s (1H), 8.76 d.d (2H, J = 4.8, 1.6 Hz),
12.29 (br. s, 1H). 13C NMR spectrum, δ, ppm: 52.6, 57.8,
99.6, 104.5, 110.3, 116.7, 121.4, 122.5, 123.7, 128.2,
129.1, 132.4, 139.7, 140.2, 142.4, 145.6, 150.3, 152.6,
159.2, 160.6, 163.5, 170.6. MS (ESI): m/z: 566 [M + H]+.
2-[4-(3,5-Dinitrophenyl)-1H-1,2,3-triazol-1-yl]-
N-(4-{5-[4-(pyridin-4-yl)thiazol-2-yl]isoxazol-3-yl}-
phenyl)acetamide (14h). Yield 59%, mp 325–327°C. 1H
NMR spectrum, δ, ppm: 5.45 s (2H), 7.72 s (1H), 7.76 d
(2H, J = 8.16 Hz), 7.88 d.d (2H, J = 4.8, 1.6 Hz), 7.95 d
(2H, J = 8.16 Hz), 8.12 s (1H), 8.41 s (1H), 8.63 s (2H),
8.77 d.d (2H, J = 4.8, 1.6 Hz), 9.23 s (1H), 12.53 br. s
(1H). 13C NMR spectrum, δ, ppm: 52.8, 104.7, 117.6,
118.7, 121.5, 122.6, 123.8, 128.5, 129.7, 133.6, 133.9,
139.3, 140.5, 142.9, 147.5, 147.9, 150.4, 152.3, 159.7,
160.8, 171.8. MS (ESI): m/z: 596 [M + H]+.
2-[4-(4-Methoxyphenyl)-1H-1,2,3-triazol-1-yl]-
N-(4-{5-[4-(pyridin-4-yl)thiazol-2-yl]isoxazol-3-yl}-
phenyl)acetamide (14d). Yield 53%, mp 268–270°C. 1H
NMR spectrum, δ, ppm: 3.79 s (3H), 5.09 s (2H), 7.14 d
(2H, J = 7.5 Hz), 7.66 s (1H), 7.70 d (2H, J = 8.10 Hz),
7.88 d.d (2H, J = 4.8, 1.6 Hz), 7.92 d (2H, J = 8.10 Hz),
8.11 s (1H), 8.34 s (1H), 8.76 d.d (2H, J = 4.8, 1.6 Hz),
12.32 br. s (1H). 13C NMR spectrum, δ, ppm: 52.7, 57.8,
104.6, 115.6, 116.8, 121.5, 122.3, 123.7, 124.2, 127.6,
128.7, 129.2, 139.3, 140.4, 142.3, 143.8, 150.4, 152.4,
159.6, 160.5, 160.9, 170.6. MS (ESI): m/z: 536 [M + H]+.
N-(4-{5-[4-(Pyridin-4-yl)thiazol-2-yl]isoxazol-3-yl}-
phenyl)-2-(4-p-tolyl-1H-1,2,3-triazol-1-yl)acetamide
(14i). Yield 52%, mp 274–276°C. 1H NMR spectrum, δ,
ppm: 2.48 s (3H), 5.12 s (2H), 7.45–7.58 m (4H), 7.67 s
(1H), 7.71 d (2H, J = 8.10 Hz), 7.88 d.d (2H, J = 4.8,
1.6 Hz), 7.91 d (2H, J = 8.10 Hz), 8.12 s (1H), 8.33 s
(1H), 8.77 d.d (2H, J = 4.8, 1.6 Hz), 12.36 br. s (1H). 13C
NMR spectrum, δ, ppm: 24.8, 52.6, 104.6, 116.7, 121.6,
122.5, 123.2, 126.7, 127.8, 128.4, 129.7, 130.6, 138.5,
139.7, 140.4, 142.6, 143.8, 150.6, 152.4, 159.6, 160.7,
170.5. MS (ESI): m/z: 520 [M + H]+.
2-[4-(4-Chlorophenyl)-1H-1,2,3-triazol-1-yl]-N-(4-
{5-[4-(pyridin-4-yl)thiazol-2-yl]isoxazol-3-yl}phenyl)-
acetamide (14e). Yield 70%, mp 258–260°C. 1H NMR
spectrum, δ, ppm: 5.24 s (2H), 7.42 d (2H, J = 7.7 Hz),
7.68 s (1H), 7.71–7.83 m (4H), 7.89 d.d (2H, J = 4.9,
1.7 Hz), 7.94 d (2H, J = 8.11 Hz), 8.11 s (1H), 8.36 s
(1H), 8.77 d.d (2H, J = 4.9, 1.7 Hz), 12.39 br. s (1H). 13C
NMR spectrum, δ, ppm: 52.6, 104.8, 117.8, 121.5, 122.7,
123.4, 129.3, 129.7, 130.4, 131.7, 131.9, 133.4, 139.7,
140.6, 142.5, 143.8, 150.7, 152.8, 159.6, 160.7, 171.4.
MS (ESI): m/z: 540 [M + H]+.
2-[4-(3,5-Dimethylphenyl)-1H-1,2,3-triazol-1-yl]-
N-(4-{5-[4-(pyridin-4-yl)thiazol-2-yl]isoxazol-3-yl}
phenyl)acetamide (14j). Yield 62%, mp 269–271°C. 1H
NMR spectrum, δ, ppm: 2.49 s (6H), 5.10 s (2H), 7.19 s
(2H), 7.38 s (1H), 7.66 s (1H), 7.70 d (2H, J = 8.09 Hz),
7.88 d.d (2H, J = 4.8, 1.6 Hz), 7.90 d (2H, J = 8.09 Hz),
8.12 s (1H), 8.31 s (1H), 8.77 d.d (2H, J = 4.8, 1.6 Hz),
12.32 br. s (1H). 13C NMR spectrum, δ, ppm: 26.8, 52.6,
104.6, 116.7, 121.6, 122.8, 123.5, 128.6, 129.4, 129.8,
131.5, 135.4, 139.5, 140.5, 141.3, 142.6, 146.5, 150.7,
152.6, 159.7, 160.5, 170.4. MS (ESI): m/z: 534 [M + H]+.
2-[4-(4-Bromophenyl)-1H-1,2,3-triazol-1-yl]-N-(4-
{5-[4-(pyridin-4-yl)thiazol-2-yl]isoxazol-3-yl}phenyl)-
acetamide (14f). Yield 45%, mp 282–284°C. 1H NMR
spectrum, δ, ppm: 5.20 s (2H), 7.39 d (2H, J = 7.6 Hz),
7.67 s (1H), 7.70–7.82 m (4H), 7.88 d.d (2H, J = 4.6,
1.5 Hz), 7.93 d (2H, J = 8.10 Hz), 8.11 s (1H), 8.35 s
(1H), 8.75 d.d (2H, J = 4.6, 1.5 Hz), 12.37 br. s (1H). 13C
NMR spectrum, δ, ppm: 52.7, 104.7, 117.6, 121.5, 122.6,
122.9, 123.8, 129.6, 129.8, 130.3, 130.5, 133.6, 139.6,
140.5, 142.5, 143.6, 150.7, 152.3, 159.7, 160.6, 171.5.
MS (ESI): m/z: 586 [M + H]+.
MTT assay. All data are presented as mean ±S.D
values. The experiments were performed in triplicates.
Individual wells of a 96-well tissue culture micro titer
plate were inoculated with 100 μL of complete me-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 89 No. 12 2019

DESIGN, SYNTHESIS, AND ANTICANCER ACTIVITY
2527
dium containing 1×104 cells. The plates were incubated
at 37°C in a humidified 5% CO2 incubator for 18 h
prior to the experiment. After removal of the medium,
100 μL of fresh medium containing the test compounds
and etoposide (Eto) at different concentrations (0.5, 1 and
2 μM) were added to each well and incubated at 37°C
for 24 h. Then the medium was discarded and replaced
with 10 μL MTT dye. Plates were incubated at 37°C for
2 h. The resulting formazan crystals were solubilized in
100 μL extraction buffer. The optical density (O.D) was
recorded at 570 nm on a micro plate reader (Multi-mode
Varioskan Instrument-Themo Scientific). The percentage
of DMSO in the medium never exceeded 0.25%.
vol. 12, p. 4633.
https://doi.org/10.1016/j.bmc.2004.06.033
3. Mayhoub,A.S., Khaliq, M., and Botting, C., Bioorg. Med.
Chem., 2011, vol. 19, p. 3845.
https://doi.org/10.1016/j.bmc.2011.04.041
4. Schade, A.E., Schieven, G.L., Townsend, R., Jankow-
ska, A.M., Susulic, V., Zhang, R., Szpurka, H., Maciejew-
ski, J.P., and Dasatinib, Blood, 2008, vol. 111, p. 1366.
5. Chao, S., Oh, S., Um, Y., Jung, J.H., Ham, J., Shin, W.S.,
and Lee, S., Bioorg. Med. Chem. Lett., 2009, vol. 19,
p. 382.
https://doi.org/10.1016/j.bmcl.2008.11.067
6. Costa, M.S., Boechat, N., Rangel, E.A., Da Silva,
F.D., de Souza, A.M.T., Rodrigues, C.R., Castro, H.C.,
Junior, I.N., Lourenco, M.C.S., Wardell, S.M.S.V.,
CONCLUSIONS
and
2006, vol. 14, p. 8644.
https://doi.org/10.1016/j.bmc.2006.08.019
Ferreira,
V.F.
Bioorg.
Med.
Chem.,
In conclusion, a series of novel 1,2,3-triazole linked
thiazole-1,2-isoxazole derivatives 14a–14j have been de-
signed, synthesized and characterized by NMR and Mass
spectral analysis. The compounds have been tested for
their anticancer activity towards MCF-7 (breast cancer),
A549 (lung cancer), Colo-205 (colon cancer), andA2780
(ovarian cancer) by the MTT method. Etoposide has been
used as a reference. The accumulated results indicate
that most of the tested compounds demonstrate good to
moderate activity against all cell lines with IC50 values
ranging from 0.01±0.009 to 19.5±5.13 μM (etoposide
IC50 range from 0.13±0.017 to 3.08±0.135 μM). The
compounds 14b, 14e, 14g, and 14h demonstrate stronger
inhibitory activity than etoposide against four cell lines.
7. Kumar, K.K., Seenivasan, S.P., Kumar, V., and Das, T.M.,
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gues, D.Q., Souza, A.M.T., Abreu, P.A., Passa-
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CONFLICT OF INTEREST
No conflict of interest was declared by the authors.
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