Synthesis, characterization and cytotoxic activity evaluation of 4-(1,2,3-triazol-1-yl) salicylic acid derivatives

Article abstract of DOI:10.1016/j.molstruc.2020.129149

A novel series of 4-(1,2,3-triazol-1-yl) salicylic acid derivatives was synthesized from 4-azidosalicylic acid and diverse alkynes using copper catalyzed azide-alkyne cycloaddition as key process and fully characterized by using different analytical techn

Full text of DOI:10.1016/j.molstruc.2020.129149

Journal of Molecular Structure 1225 (2021) 129149
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstr
Synthesis, characterization and cytotoxic activity evaluation of
4
-(1,2,3-triazol-1-yl) salicylic acid derivatives
Zita G. Ríos-Malváeza,b, Ma-Angeles Cano-Herrera , Juan Carlos Dávila-Becerril ,
a,b
a
a
c
c
Gustavo Mondragón-Solórzano , María Teresa Ramírez-Apan , David Morales-Morales ,
a,c
Joaquín Barroso-Flores , Jonnathan G. Santillán-Benítez , M.V. Basavanag Unnamatlaa,b,
b
a,b
a,b
a,b,∗
Marco Antonio García-Eleno , Nelly González-Rivas , Erick Cuevas-Yañez
a
Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM. Carretera Toluca-Atlacomulco Km 14.5, Universidad Autónoma del Estado de
México, Toluca, Estado de México, 50200, México
b
Facultad de Química, Universidad Autónoma del Estado de México. Paseo Colón esq. Paseo Tollocan, 50120, Toluca, Mexico
c
Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior S. N., Ciudad Universitaria, Coyoacán, Ciudad de México, 04510, Mexico
a r t i c l e i n f o
a b s t r a c t
Article history:
A novel series of 4-(1,2,3-triazol-1-yl) salicylic acid derivatives was synthesized from 4-azidosalicylic acid
and diverse alkynes using copper catalyzed azide-alkyne cycloaddition as key process and fully charac-
terized by using different analytical techniques. The in vitro antiproliferative activity of these new com-
pounds was explored against a series of tumoral cell lines which included U251 (human glioblastoma),
PC-3 (human prostate cancer cell line), K562 (human leukemia), HCT-15 (human colorectal adenocarci-
noma), MCF-7 (human breast adenocarcinoma) and SKLU (human lung adenocarcinoma), showing selec-
tive activity in some compounds. Moreover, molecular docking studies suggest a strong interaction be-
tween ARG-154 in STAT3 and the triazole fragment which can explain the inhibitory activity observed in
these compounds.
Received 10 May 2020
Revised 7 August 2020
Accepted 26 August 2020
Available online 26 August 2020
Keywords:
1,2,3-Triazoles
anticancer
click chemistry
salicylic acid derivatives
©
2020 Elsevier B.V. All rights reserved.
1. Introduction
Nowadays cancer represents one of the most challenging dis-
eases in the world. In this regard, the signal transducer and ac-
tivator of transcription 3 (STAT3) is a cytosolic protein identi-
fied as a key regulator of human cancers that contributes to un-
controlled differentiation, proliferation, survival and tumorigenesis.
Recent studies have shown that STAT3 factor is active in many
types of cancer including breast, stomach, brain and lung [1].
STAT3 belongs to a family of transcription factors (TFs) of STAT
type (signal transducer and activator of transcription) which play
an important role in cell growth described in the activation of
about 70% of both solid and hematological tumors [2]. Hence,
some current therapies aimed to treat various types of cancer are
based on the inhibition of the STAT3 factor using diverse com-
pounds such as N-[2-(1,3,4-oxadiazolyl)]-4-quinolinecarboxamide
derivatives [3], anthraquinone compounds [4,5], bis-dipicolylamine
copper(II) complexes [6], and 4-aminosalicylic acid derivatives
Scheme 1. Structure of 4-aminosalicylic acid derivatives 1 and general structure for
molecules 2 proposed in this work.
activity by inhibition of the STAT3 phosphorylation process induc-
ing apoptosis in cell lines at low concentrations [7–9].
These elements prompted us to investigate the possible appli-
cation of CuAAC reaction, the best-known click reaction, in the
preparation of a series of 4-aminosalicylic acid derivatives. Because
1,2,3-triazoles derived from CuAAC reaction are amide bioisosteres
and biocompatible molecular structures for drug design [10–13],
we proposed the synthesis of triazolyl salicylic acid derivatives 2
as 4-aminosalicylic acid derivatives aimed to find more and bet-
ter STAT3 inhibitors. Herein is described a summary of our recent
successful endeavors in this area.
(molecule 1, scheme 1) that have demonstrated antiproliferative
∗
Corresponding author.
E-mail address: ecuevasy@uaemex.mx (E. Cuevas-Yañez).
https://doi.org/10.1016/j.molstruc.2020.129149
022-2860/© 2020 Elsevier B.V. All rights reserved.
0

2
Z.G. Ríos-Malváez, M.-A. Cano-Herrera and J.C. Dávila-Becerril et al. / Journal of Molecular Structure 1225 (2021) 129149
Scheme 2. Structure of 4-(1,2,3-triazol-1-yl) salicylic acid derivatives 4-17.
Scheme 3. Synthesis of 4-(1,2,3-triazol-1-yl) salicylic acid derivatives.
2. Experimental
QP2010 Plus in the EI mode, 70 eV, 200°C via direct inlet probe.
Only the molecular and parent ions (m/z) are reported. IR spectra
were recorded on a Bruker TENSOR 27 FT instrument.
2
.1. General Remarks
The starting materials were purchased from Aldrich Chemical
2.2. Synthesis of 4-Azido-2-hydroxybenzoic acid (3)
Co. and were used without further purification. Solvents were dis-
tilled before use. Silica plates of 0.20 mm thickness were used for
thin layer chromatography. Melting points were determined with a
Krüss Optronic melting point apparatus and they are uncorrected.
1H and 13C NMR spectra were recorded using a Bruker Avance 300
MHz, and a Varian 500 MHz; the chemical shifts (δ) are given
in ppm relative to TMS as internal standard (0.00). For analytical
purposes the mass spectra were recorded on a Shimadzu GCMS-
Typical procedure. A solution of NaNO2 (1.3 g, 18.84 mmol)
in H O (12.5 mL) was added to a cold solution of 4-amino-2-
2
hydroxybenzoic acid (2.06 g, 13.46 mmol) and H SO (5mL) in
2
4
H O (30 mL) and the resulting mixture was stirred at 0°C for 20
min. Urea (7 g) was added keeping the temperature at 0°C and
2
a solution of NaN3 (2 g, 30.7 mmol) in H O (10 mL) was added.
2
The product was filtered under reduced pressure and washed with

Z.G. Ríos-Malváez, M.-A. Cano-Herrera and J.C. Dávila-Becerril et al. / Journal of Molecular Structure 1225 (2021) 129149
3
Scheme 4. Fragmentation mechanisms for 4-(1,2,3-triazol-1-yl) salicylic acid derivatives.
cold H O (30 mL). Purification by crystallization (EtOH) afforded
4-[4-(4-Bromophenoxymethyl)-1,2,3-triazol-1-yl]-2-hydroxy-benzoic
2
4-Azido-2-hydroxybenzoic acid 3 as pale-yellow solid (2.07 g, 11.5
acid (5)
mmol, 86 %), m. p. 160°C (lit. 160-161°C) [14]. UV (MeOH) λmax
4-azido-2-hydroxybenzoic acid
3
and 1-Bromo-4-prop-2-
(
log ε) 272 (1.197), 310 (0.589) nm. IR (ATR) νmax 3600, 3200, 2104,
ynyloxy-benzene afforded 4-[4-(4-Bromophenoxymethyl)-1,2,3-
triazol-1-yl]-2-hydroxy-benzoic acid as a white solid. Yield: 0.298
g (73 %), m.p. 190°C. UV (MeOH) λmax (log ε) 255 (0.101) nm.
IR (ATR) νmax 3180, 3100, 1680, 1600, 1450, 1287, 820, 790, 700
757 cm 1. 1H NMR: (300 MHz, CDCl ) δ = 8.91 (s, 1H), 8.49 (s,
−
1
3
13
1
H), 7.59 – 7.22 (m, 2H). C NMR: (75 MHz, CDCl ) δ = 170.75 (C),
3
1
69.34 (C), 145.43 (C), 124.93 (CH), 112.42 (CH), 108.02 (C), 107.35
(
CH).
cm 1. 1H NMR: (300 MHz, DMSO-d ) δ 8.96 (s, 1H), 8.49 (s, 1H),
−
6
7
.86 (d, J = 8.1 Hz, 1H), 7.55 – 7.41 (m, 2H), 7.25 (d, J = 8.8
Hz, 2H), 7.10 – 7.03 (m, 2H), 5.22 (s, 2H). 13C NMR: (75 MHz,
DMSO-d6) δ = 170.55 (C), 163.94 (C), 157.25 (2xC), 143.47 (C),
2
.3. General procedure of synthesis of 4-(1,2,3-triazol-1-yl) salicylic
1
39.44 (C), 132.19 (2xCH), 131.49 (CH), 122.93 (C), 117.11 (2xCH),
acid derivatives
1
12.42 (CH), 107.97 (CH), 107.35 (CH), 61.20 (CH ). MS [EI+] m/z
2
+
+
+
%): 189 [M] (12), 190 [M-C10H N O] (89), 172 [M-C H9NO ]
3
(
(
(
5
3
9
A solution of the corresponding alkyne (1.0 mmol) in CH Cl2
2
+
100), 114 [M-C13H13 N O ]
3
(40). Anal. calcd. for C16 H12BrN O
3
4
4
(
0.5 mL) was added to a solution of 4-azido-2-hydroxybenzoic acid
%): C 49.25, H 3.10, N 10.77; found: C 49.29, H 3.07, N 10.71.
3 (11.43 mmol), CuI (0.010 g, 0.052 mmol) and DIPEA (0.5 mL) in
CH Cl (1.5 mL). The mixture was stirred at room temperature for
2
2
2-Hydroxy-4-[4-(3-isopropyl-5-methyl-phenoxymethyl)-
2
4 h. The solvent was removed under reduced pressure, a 0.2 %
1,2,3-triazol-1-yl]-benzoic acid (6)
aqueous solution of EDTA (5 mL) was added and the mixture was
stirred at room temperature for 30 min. A 1 M HCl solution was
4
-azido-2-hydroxybenzoic acid
3
and 1-isopropyl-3-methyl-
5
-prop-2-ynyloxy-benzene afforded 2-hydroxy-4-[4-(3-isopropyl-5-
added (2 mL) and the product was filtered and washed with H O
2
methyl-phenoxymethyl)-1,2,3-triazol-1-yl]-benzoic acid as a white
solid. Yield: 0. 189 g (43 %), m.p. 202°C. UV (MeOH) λmax (log
ε) 257 (0.315), 313 (0.133) nm. IR (ATR) νmax 3600, 3200, 1680,
(
5 mL). The product was purified by crystallization (MeOH). Com-
pounds 4-17 are represented in Scheme 2.
−
1
600, 1450, 1290 cm 1. 1H NMR: (300 MHz, DMSO-d ) δ 8.87 (s,
6
1
H), 7.99 (d, J = 8.5 Hz, 1H), 7.59 – 7.36 (m, 2H), 6.86 – 6.50
4
-(4-((2,4-dinitrophenoxy)methyl)-1,2,3-triazol-1-yl)-2-hydroxy-
benzoic acid (4)
-azido-2-hydroxybenzoic acid 3 and 2,4-dinitro-1-prop-2-
(
m, 3H), 5.19 (s, 2H), 2.83 (p, J = 6.9 Hz, 1H), 1.21 (d, J = 6.9
13
Hz, 6H). C NMR: (75 MHz, DMSO-d ) δ = 171.25 (C), 162.42
6
4
(
C), 157.93 (C), 149.81 (C), 144.25 (C), 140.95 (C), 131.87 (CH),
22.25 (CH), 119.79 (CH), 113.50 (CH), 112.24 (CH), 109.86 (CH),
09.75 (CH), 107.52 (CH), 60.77 (CH ), 33.43 (CH ), 23.66 (CH ),
ynyloxy-benzene afforded 4-(4-((2,4-dinitrophenoxy)methyl)-1,2,3-
triazol-1-yl)-2-hydroxybenzoic acid as a white solid. Yield: 0.127g
1
1
2
3
3
(
34 %), m. p. 200°C. UV (MeOH) λmax (log ε) 256 (0.090) nm. IR
+
+
2
1.20 (CH ). MS [EI+] m/z (%): 367 [M] (21), 190 [M-C12H17 O]
3
ATR) νmax 3200, 2900, 1700, 1640, 1600, 1520, 1480, 1300 cm 1
−
.
(
1
+
65), 172 [M-C H N O ] (75), 150 [M-C H O N ] (96), 135 [M-
8 9 3 3 10 7 3
+
C13H18 ON3] (100), 119 [M-C H O ] (40), 91 [M-C14 H16 N O ]
4
+
(
3
H NMR: (300 MHz, DMSO-d ) δ 14.84 (s, 1H), 11.54 (s, 1H), 8.74
+
+
6
5
11
3
2
(
(
t, J = 3.0 Hz, 1H), 8.49 (dd, J = 9.1, 3.0 Hz, 1H), 8.41 (s, 1H), 8.04
s, 1H), 7.74 (d, J = 9.2 Hz, 1H), 7.53 (d, J = 3.2 Hz, 1H), 7.27 (s, 1H),
(
75). Anal. calcd. for C20H21N O (%): C 65.38, H 5.76, N 11.44;
3 4
found: C 65.45, H 5.71, N 11.41.
13
7
.19 (s, 1H), 5.61 (s, 2H). C NMR: (75 MHz, DMSO-d ) δ = 155.36
6
(
(
C), 139.74 (C), 138.41 (2XC), 128.66 (2xCH), 121.84 (CH), 121.11
4-[4-(4-Formyl-2-methoxy-phenoxymethyl)-1,2,3-triazol-1-yl]-
2xCH), 115.22 (CH), 108.47 (CH), 107.42 (C), 63.30 (CH ). MS [EI+]
2-hydroxy-benzoic acid (7)
2
+
+
m/z (%): 401 [M] (5), 172 [M-C1 H N O ] (100). Anal. calcd. for
4-azido-2-hydroxybenzoic acid
2-ynyloxy-benzaldehyde afforded
3
and 3-methoxy-4-prop-
4-[4-(4-formyl-2-methoxy-
0
9
3
3
C16 H11 N O (%): C 47.89, H 2.76, N 17.45; found: C 47.85, H 2.77, N
5
8
17.41.
phenoxymethyl)-1,2,3-triazol-1-yl]-2-hydroxy-benzoic acid as a

4
Z.G. Ríos-Malváez, M.-A. Cano-Herrera and J.C. Dávila-Becerril et al. / Journal of Molecular Structure 1225 (2021) 129149
pale-yellow solid. Yield: 0.298 g (84 %), m.p. 185°C. UV (MeOH)
max (log ε) 273 (0.0451), 312 (0.037) nm. IR (ATR) νmax 3500,
4-[4-(4-Acetyl-2-methoxy-phenoxymethyl)-1,2,3-triazol-1-yl]-
λ
2-hydroxy-benzoic acid (11)
200, 1680, 1640, 1470, 1265 cm 1. 1H NMR: (300 MHz, DMSO-d6)
δ 9.79 (s, 1H), 8.88 (s, 1H), 7.75 (d, J = 8.1 Hz, 1H), 7.52 (dd, J = 8.3,
.9 Hz, 1H), 7.37 (d, J = 8.4 Hz, 1H), 7.35 (d, J = 1.8 Hz, 1H), 7.13 –
.01 (m, 2H), 5.26 (s, 2H), 3.75 (s, 3H). 13C NMR: (75 MHz, DMSO-
d ) δ = 191.50 (C), 170.44 (C), 164.72 (C), 152.76 (C), 149.33(C),
−
4-azido-2-hydroxybenzoic acid
2-ynyloxy-phenyl)ethanone afforded 4-[4-(4-Acetyl-2-methoxy-
phenoxymethyl)-1,2,3-triazol-1-yl]-2-hydroxy-benzoic acid as
pale yellow solid. Yield: 0.140 g 81 %), m.p. 210°C. UV (MeOH)
3 and 1-(3-methoxy-4-prop-
3
1
a
7
λ
max (log ε) 270 (0.226), 307 (0.154) nm. IR (ATR) νmax 3200, 1680,
6
1590, 1490, 1270 cm 1. 1H NMR: (300 MHz, DMSO-d ) δ 9.07 (s,
−
142.86 (C), 138.73(C), 131.21 (CH), 130.02 (CH), 125.93 (CH), 123.31
6
(
CH), 120.31 (CH), 112.68 (C), 109.71 (C), 107.26 (CH), 107.04 (CH),
1H), 7.97 (d, J = 8.2 Hz, 1H), 7.65 (dd, J = 8.4, 2.0 Hz, 1H), 7.55
+
13
6
1.58 (CH ), 55.51 (CH ). MS [EI+] m/z (%): 369[M] (5), 310
– 7.41 (m, 3H), 7.32 (d, J = 8.4 Hz, 1H), 5.33 (s, 2H). C NMR:
2
3
+
+
[M-C H O ] (10), 190 [M-C H9NO ] (61), 172 [M-C H N O ]
(75 MHz, DMSO-d ) δ = 196.39 (C), 171.55 (C), 170.94 (C), 162.50
2
3
2
9
3
8
11
3
3
6
+
+
+
(
72), 151 [M-C10H8 N O ] (100), 133 [M-C12H16 N O ] (59),
(C), 151.54 (C), 148.73 (C), 143.44 (C), 140.68 (C), 132.06 (CH),
130.37 (CH), 123.36 (CH), 122.89 (CH), 112.38 (CH), 110.44 (CH),
3
3
2
3
+
1
05 [M-C13H16 N O ]
(72). Anal. calcd. for C18 H15N 5O (%): C
2
4
3
6
5
8.54, H 4.09, N 11.38; found: C 58.57, H 4.07, N 11.35.
109.80 (C), 107.67 (CH), 61.44 (CH ), 55.46 (CH ), 26.34 (CH ).
2 3 3
+
+
MS [EI+] m/z (%): 383[M] (5), 204 [M-C H N O] (90), 165
9
13
3
+ +
[M-C H N O] (100), 114 [M-C16 H19N O] (75). Anal. calcd. for
12 16 3 3
2-Hydroxy-4-[4-(pyrimidin-2-ylsulfanylmethyl)-
1,2,3-triazol-1-yl]-benzoic acid (8)
C19 H17 N O (%): C 59.53, H 4.47, N 10.96; found: C 59.55, H 4.43,
3 6
4
-azido-2-hydroxybenzoic
acid
3
and
2-prop-2-
N 10.98.
ynylsulfanyl-pyrimidine afforded 2-hydroxy-4-[4-(pyrimidin-2-
ylsulfanylmethyl)-1,2,3-triazol-1-yl]-benzoic acid as a pale-yellow
solid. Yield: 0.078 g (64 %), m.p. 205°C. UV (MeOH) λmax (log ε)
2-Hydroxy-4-[4-(1-hydroxycyclohexyl)-1,2,3-triazol-1-yl]-benzoic
acid (12)
2
74 (0.400), 311 (0.338) nm. IR (ATR) νmax 3150, 3060, 1660, 1610,
4-azido-2-hydroxybenzoic acid 3 and 1-ethynylcyclohexanol
560, 1450, 1380, 1300 cm 1. 1H NMR: (300 MHz, DMSO-d ) δ
−
afforded 2-hydroxy-4-[4-(1-hydroxycyclohexyl)-1,2,3-triazol-1-yl]-
benzoic acid as a pale-yellow solid. Yield: 0.267 g (88 %), m.p.
225°C UV (MeOH) λmax (log ε) 235 (0.198), 257 (0.461) nm. IR
1
6
8
.76 (s, 1H), 8.62 (d, J = 4.9 Hz, 2H), 7.86 (s, 1H), 7.46 (s, 1H), 7.40
13
(
s, 1H), 7.19 (t, J = 4.9 Hz, 1H), 4.46 (s, 2H). C NMR: (75 MHz,
DMSO-d6) δ = 169.93 (2xC), 157.94 (2xCH), 144.98 (C), 140.94 (C),
32.41 (CH), 121.71 (CH), 117.50 (2xCH), 110.00 (CH), 107.81 (C),
(ATR) νmax 3250, 3140, 2900, 2800, 1650, 1620, 1440, 1300 cm 1.
−
1
1
H NMR: (300 MHz, DMSO-d ) δ 8.67 (s, 1H), 7.93 – 7.85 (m, 1H),
6
+
5
+
3.55 (CH ). MS [EI+] m/z (%): 329[M]
(30), 227 [M-C H N S]
6
7.51 – 7.42 (m, 2H), 1.88 (ddd, J = 13.8, 10.4, 3.8 Hz, 2H), 1.76 –
2
3
2
+
+
13
(
30), 172 [M-C H N S]
(100), 119 [M-C H N OS]
(60).
1.59 (m, 4H), 1.44 – 1.31 (m, 3H), 1.23 – 1.17 (m, 1H). C NMR:
4
7
5
9
12
3
Anal. calcd. for C14 H11 N O S (%): C 51.06, H 3.37, N 21.27; found:
(75 MHz, DMSO-d ) δ = 171.13 (C), 162.21(C), 156.92 (C), 141.45
5
3
6
C 51.09, H 3.39, N 21.28.
(C), 132.14 (CH), 119.50 (CH), 113.06 (C), 109.99 (CH), 107.29 (CH),
6
7.89 (CH ), 37.56 (2xCH ), 25.21 (CH ), 21.68 (2xCH ). MS [EI+]
2
2
2
2
+
+
+
m/z (%): 303 [M] (5), 190 [M-C H N] (60), 172 [M-C H N ]
2
4
-[4-(4-Chloro-phenoxymethyl)-1,2,3-triazol-1-yl]-2-hydroxy-benzoic
acid (9)
-azido-2-hydroxybenzoic acid
5
11
8
7
+
(55), 114 [M-C10H11 N O] (100),
3
+
4
3
and 1-chloro-4-prop-2-
72 [M-C14 H21N ] (90). Anal. calcd. for C15H17 N O (%): C
3
3
4
ynyloxy-benzene afforded 4-[4-(4-chloro-phenoxymethyl)-1,2,3-
triazol-1-yl]-2-hydroxy-benzoic acid as a pale-yellow solid. Yield:
59.40, H 5.65, N 13.85; found: C 59.43, H 5.67, N 17.87.
0
.309 g (89 %), m.p. 199-200°C. UV (MeOH) λmax (log ε) 273
2-Hydroxy-4-[4-(1-methyl-2,5-dioxo-cyclopentylmethyl)-
(
0.053), 312 (0.045) nm. IR (ATR) νmax 3550, 3200,1680, 1600,
1,2,3-triazol-1-yl]-benzoic acid (13)
480, 1310 cm 1. 1H NMR: (300 MHz, DMSO-d ) δ 9.08 (s, 1H),
−
4-azido-2-hydroxybenzoic acid 3 and 2-methyl-2-prop-2-ynyl-
cyclopentane-1,3-dione afforded 2-hydroxy-4-[4-(1-methyl-2,5-
dioxo-cyclopentylmethyl)-1,2,3-triazol-1-yl]-benzoic acid as a pale
yellow solid. Yield: 0.136 g (41 %), m.p. 185°C. UV (MeOH) λmax
(log ε) 256 (0.0239), 270 (0.201) nm. IR (ATR) νmax 3110, 1680,
1605, 1440, 1400, 1305, 1200cm . 1H NMR: (300 MHz, DMSO-d6)
δ 8.55 (s, 1H), 7.89 (d, J = 8.4 Hz, 1H), 7.29 (d, J = 7.7 Hz, 3H),
3.03 (s, 2H), 2.89 – 2.67 (m, 4H), 1.14 (s, 4H). 13C NMR: (75 MHz,
1
6
7
.96 (s, 1H), 7.63 (s, 1H), 7.54 (s, 1H), 7.41–7.32 (m, 2H), 7.16 – 7.07
(
(
m, 2H), 5.25 (s, 2H). 13C NMR: (75 MHz, DMSO-d ) δ = 156.71
6
C), 143.84 (C), 141.09 (C), 129.26 (2xCH), 129.18 (C), 124.69 (CH),
1
23.04 (CH), 116.61 (C), 116.52 (2xCH), 110.36 (CH), 108.12 (C),
+
+
−1
6
1.19 (CH ). MS [EI+] m/z (%): 345 [M] (14), 190 [M-C H N O]
2
7
3
3
+ +
81), 172 [M-C H9NO ] (100), 128 [M-C11 H11 N O ] (49). Anal.
9 3 3 2
(
calcd. for C16 H12ClN O4 (%): C 55.58, H 3.50, N 12.15; found: C
3
5
5.51, H 3.54, N 12.17.
DMSO-d ) δ = 216.10 (2xC), 171.89 (2xC), 163.05(C), 143.40 (C),
6
1
40.23 (C), 131.90 (CH), 120.85 (CH), 108.99 (CH), 107.37 (CH),
4
-[4-(2-Chloro-phenoxymethyl)-1,2,3-triazol-1-yl]-2-hydroxy-benzoic
54.86 (C), 54.66 (2xCH ), 34.77 (CH ), 20.27 (CH ). MS [EI+] m/z
2
2
3
+
+
+
(%): 329 [M] (15), 190 [M-C H NO ] (53), 172 [M-C H NO ]
2
acid (10)
-azido-2-hydroxybenzoic acid
7
9
2
8
15
+
(70), 42 [M-C16 H21N O ] (100). Anal. calcd. for C16 H15N O (%):
3 2 3 5
4
3
and 1-chloro-2-prop-2-
ynyloxy-benzene afforded 4-[4-(2-chloro-phenoxymethyl)-1,2,3-
triazol-1-yl]-2-hydroxy-benzoic acid as a white solid. Yield: 0.247
g (68 %), m.p. 200-201°C. UV (MeOH) λmax (log ε) 273 (0.052),
C 58.36, H 4.59, N 12.76; found: C 58.38, H 4.61, N 12.74.
4-[4-(Benzothiazol-2-ylsulfanylmethyl)-1,2,3-triazol-1-yl]-
3
11 (0.044) nm. IR (ATR) νmax 3200, 2800, 1680, 1600, 1440,
2-hydroxy-benzoic acid (14)
295 cm 1. 1H NMR: (300 MHz, DMSO-d ) δ 9.03 (s, 1H), 7.92
−
4-azido-2-hydroxybenzoic acid 3 and 2-prop-2-ynylsulfanyl-
1
6
(
d, J = 8.3 Hz, 1H), 7.52 – 7.45 (m, 2H), 7.41 – 7.22 (m, 4H),
benzothiazole afforded 4-[4-(Benzothiazol-2-ylsulfanylmethyl)-
1,2,3-triazol-1-yl]-2-hydroxy-benzoic acid as a white solid. Yield:
0.169 g (42 %), m.p. 205°C. UV (MeOH) λmax (log ε) 281 (0.032)
13
6
.94 (dd, J = 7.4, 1.6 Hz, 1H), 5.27 (s, 2H). C NMR: (75 MHz,
DMSO-d ) δ = 171.04 (C), 162.42 (C), 152.51 (C), 146.44 (C), 141.09
6
nm. IR (ATR) νmax 3560, 2990, 1680, 1460, 1380, 1330, 1230 cm 1.
−
(
(
CH), 130.08 (CH), 128.33 (CH), 128.15 (C), 123.26 (CH), 122.21
1
CH), 122.03 (CH), 121.49 (C), 107.77 (CH), 106.83 (C), 61.77 (CH ).
H NMR: (300 MHz, DMSO-d ) δ 8.80 (s, 1H), 7.99 (d, J = 8.1
2
6
+
+
MS [EI+] m/z (%): 345 [M] (9), 190 [M-C H N O] (65), 172
Hz, 1H), 7.90 (t, J = 9.1 Hz, 2H), 7.47 (t, J = 7.6 Hz, 1H), 7.36 (t,
7
3
3
+
+
2
13
[M-C H9NO ] (100), 128 [M-C11 H11 N O ] (50). Anal. calcd. for
J = 7.3 Hz, 1H), 7.26 (d, J = 8.1 Hz, 2H), 4.76 (s, 2H). C NMR:
9
3
3
C16 H12ClN O4 (%): C 55.58, H 3.50, N 12.15; found: C 55.59, H 3.56,
(75 MHz, DMSO-d ) δ = 171.57 (C), 165.69 (2xC), 152.71 (C),
3
6
N 12.13.
140.0 (C), 134.87 (C), 131.92 (C), 126.62 (C), 126.55 (CH), 124.73

Z.G. Ríos-Malváez, M.-A. Cano-Herrera and J.C. Dávila-Becerril et al. / Journal of Molecular Structure 1225 (2021) 129149
5
(
2xCH), 121.91 (2xCH), 121.43 (2xCH), 108.76 (CH), 107.52 (CH),
Institute (USA); SKLU-1 (human lung adenocarcinoma) from Na-
tional Institute of Cancerology, Mexico, and COS-7, adherent mon-
key kidney fibroblasts (ATTC).
+
+
5
1.22 (CH ). MS [EI+] m/z (%): 384[M] (5), 248 [M-C H N ]
2
7
10
3
+ +
30), 166 [M-C10H N O ] (50), 69 [M-C15H16 N S ] (100), 55
10 3 3 4 2
(
[
+
M-C16 H26N S ] (90). Anal. calcd. for C17 H12N O S (%): C 53.11,
The human tumor cytotoxicity was determined using the
protein-binding dye sulforhodamine B (SRB) in microculture assay
to measure cell growth, as described in the protocols established
by the NCI [15]. The cell lines were cultured in RPMI-1640 medium
supplemented with 10% fetal bovine serum, 2mM L-glutamine,
Penicillin-Streptomycin solution 100x (Gibco) and 1% non-essential
amino acids (Gibco®). They were maintained at 37°C in humidi-
4
2
4
3 2
H 3.15, N 14.57; found: C 53.18, H 3.17, N 14.54.
4
-[4-(1H-Benzoimidazol-2-ylsulfanylmethyl)-
1
,2,3-triazol-1-yl]-2-hydroxy-benzoic acid (15)
4
-azido-2-hydroxybenzoic acid
3
and 2-prop-2-ynylsulfanyl-
4-[4-(1H-benzoimidazol-2-
1
H-benzoimidazole afforded
ylsulfanylmethyl)-1,2,3-triazol-1-yl]-2-hydroxy-benzoic acid
as
fied atmosphere with 5% CO . The viability of the cells used in the
2
a white solid. Yield: 0.228 g (62 %), m.p. 220°C. UV (MeOH) λmax
experiments exceed 95% as determined with trypan blue.
(
log ε) 256 (0.218) nm. IR (ATR) νmax 3026, 1670, 1610, 1560, 1450,
290, 1230 cm 1. 1H NMR: (300 MHz, DMSO-d ) δ 8.92 (s, 1H),
−
2.5. Cytotoxicity assay
1
6
8
2
.82 (s, 1H), 7.91 (d, J = 8.4 Hz, 2H), 7.64 (ddd, J = 8.8, 6.0, 2.8 Hz,
13
H), 7.41 (d, J = 7.3 Hz, 3H), 7.24 – 7.18 (m, 2H), 5.54 (s, 2H).
C
Cytotoxicity after treatment of the tumors cells and normal
cell with the test compounds was determined using the protein-
binding dye sulforhodamine B (SRB) in microculture assay to mea-
sure cell growth as described in the reference [15]. The cells were
removed from the tissue culture flasks by treatment with trypsin
and diluted with fresh media. Of this cell suspension, 100 μl con-
taining 5000-10,000 cell per well, were pipetted into 96 well mi-
crotiter plates (Costar) and the material was incubated at 37°C for
24 h in a 5% CO2 atmosphere. Each cell line is deposited by tripli-
cate and subsequently, 100 μl of a solution of the compound ob-
tained by diluting the stocks were added to each well. The cultures
were exposed for 48 h to the compound at concentrations 25 μM.
After the incubation period, cells were fixed to the plastic substra-
tum by the addition of 50 μl of cold 50 % aqueous trichloroacetic
acid. The plates were incubated at 4°C for 1 h, washed with tap
NMR: (75 MHz, DMSO-d ) δ = 171.47 (C), 171.00 (C), 150.38 (C),
6
143.34 (C), 142.97 (C), 140.71 (C), 140.59 (C), 132.05 (2xCH), 122.07
(
CH), 121.95 (CH), 117.93 (CH), 110.17 (C), 109.76 (CH), 107.60 (CH),
+
1
07.55 (CH), 54.56 (CH ). MS [EI+] m/z (%): 367 [M] (40), 210
2
+
+
+
[
(
M-C H N S] (20), 188 [M-C H N O ] (35),172 [M-C H N S]
5
9
4
7
5
3
3
9
13
3
+
+
50), 146 [M-C10H13N S] (100), 88 [M-C14 H15N S] (40). Anal.
4
5
calcd. for C17 H13N O S (%): C 55.58, H 3.57, N 19.06; found: C
5
3
5
5.55, H 3.59, N 19.11.
4-[4-(4-Formylphenoxymethyl)-1,2,3-triazol-1-yl]-2-hydroxy-benzoic
acid (16)
4
-azido-2-hydroxybenzoic acid
3
and 4-prop-2-ynyloxy-
4-[4-(4-formylphenoxymethyl)-1,2,3-
white solid. Yield:
.290 g (85 %), m.p. 210°C. UV (MeOH) λmax (log ε) 273 (0.208)
nm. IR (ATR) νmax 3100, 1690, 1600, 1500, 1480, 1300, 1250
benzaldehyde
afforded
triazol-1-yl]-2-hydroxy-benzoic acid as
a
0
H O, and air-dried. The trichloroacetic-acid-fixed cells were stained
2
by the addition of 0.4% SRB. Free SRB solution was the removed by
washing with 1% aqueous acetic acid. The plates were the air-dried,
and the bound dye was solubilized by the addition of 10 mM un-
buffered Tris base (100 μl). The plates were placed on a shaker for
10 min, and the absorption was determined at 515 nm using an
ELISA plate reader (Bio-Tex Instruments).
cm 1. 1H NMR: (300 MHz, DMSO-d ) δ 9.89 (s, 1H), 9.06 (s, 1H),
8
−
6
.00 (d, J = 8.3 Hz, 1H), 7.90 (d, J = 7.9 Hz, 2H), 7.53 (s, 1H),
13
7
.26 (dd, J = 8.9, 5.5 Hz, 2H), 5.38 (s, 2H). C NMR: (75 MHz,
DMSO-d ) δ = 191.09 (C), 171.27 (C), 162.26(C), 162.23 (C), 143.53
6
(
C), 141.25 (C), 132.21 (CH), 131.83 (2xCH), 130.01 (C), 123.09 (CH),
15.20 (2xCH), 113.05 (CH), 110.36 (C), 107.79 (CH), 61.32 (CH ).
1
2
+
+
MS [EI+] m/z (%): 339 [M] (15), 190 [M-C H N O] (85), 172
2.6. Molecular modeling
7
7
3
+
M-C H N O] (100). Anal. calcd. for C17 H13N O (%): C 60.18, H
8 13 3 3 5
[
3
.86, N 12.38; found: C 60.19, H 3.88, N 12.36.
All optimizations of compounds 4-17 were performed at
ωB97X-D/6-311+G(d,p) level of theory. Frequencies were calculated
to confirm that the structures are on an energetic minimum. For
docking calculations, the PDB files of STAT 3 protein (1BHH for SH2
domain and 4ZIA for N-terminal domain) were used from Protein
Data Bank. The best binding modes were chosen by binding en-
ergy and the type of interactions between the aminoacids and the
compounds 4-17. These binding sites were isolated and partially
optimized, leaving backbone atoms fixed and sidechains flexibles.
Also, hydrogens on backbone atoms were optimized. A first pre-
optimization with PM6 semiempirical method was performed and
a ωB97X-D/cc-pVDZ level of theory partial optimization were per-
formed later. Non-Covalent Interactions index (NCI) was performed
on these sites for a complete study of the intermolecular interac-
tions on binding sites. Geometry optimizations with quantum me-
chanics methods were performed with Gaussian09 Rev. E.01 pack-
age [16], and docking calculations were performed with AutoDock-
Tools 1.5.6 version package [17]. NCI análisis were performed with
a DensToolkit development version [18].
4-[4-(2-Formylphenoxymethyl)-1,2,3-triazol-1-yl]-2-hydroxy-benzoic
acid (17)
4
-azido-2-hydroxybenzoic acid
3
and 2-prop-2-ynyloxy-
benzaldehyde
afforded
4-[4-(2-Formylphenoxymethyl)-1,2,3-
triazol-1-yl]-2-hydroxy-benzoic acid as a white solid. Yield: 0.252g
(
78 %), 220°C. UV (MeOH) λmax (log ε) 273 (0.324) nm. IR (ATR)
νmax 3440, 1685, 1675, 1600, 1485, 1280, 1200 cm 1. 1H NMR:
−
(
300 MHz, DMSO-d ) δ 10.38 (s, 1H), 9.06 (s, 1H), 7.91 (d, J = 8.4
6
Hz, 1H), 7.64 (dd, J = 11.6, 7.6 Hz, 2H), 7.54 – 7.35 (m, 3H), 7.06
13
(
t, J = 7.5 Hz, 1H), 5.39 (s, 2H). C NMR: (75 MHz, DMSO-d )
6
δ = 189.44 (C), 170.99 (C), 162.28 (C), 160.27 (C), 143.91 (C), 140.92
C), 136.37 (CH), 132.12 (CH), 127.62 (CH), 124.57 (C), 122.78 (C),
21.29 (CH), 114.15 (CH), 110.07 (CH), 107.69 (CH), 106.77 (C), 62.17
(
1
+
+
(
(
CH ). MS [EI+] m/z (%): 401 [M] (5), 172 [M-C10H9N3O3]
2
100). Anal. calcd. for C17
H N O (%): C 60.18, H 3.86, N 12.38;
13 3 5
found: C 60.15, H 3.84, N 12.39.
2
.4. Cell lines culture and culture medium
3. Results and discussion
The compounds were screened in vitro against human cancer
cell lines: HCT-15 (human colorectal adenocarcinoma), MCF-7 (hu-
man mammary adenocarcinoma), K562 (human chronic myeloge-
nous leukemia), U251 (human glioblastoma), PC-3 (human pro-
static adenocarcinoma) which were supplied by National Cancer
3.1. Chemistry
Initial studies were focused to prepare 4-azido-2-
hydroxybenzoic acid
3 from a modification of the procedure

6
Z.G. Ríos-Malváez, M.-A. Cano-Herrera and J.C. Dávila-Becerril et al. / Journal of Molecular Structure 1225 (2021) 129149
Table 1
Synthesis of 4-(1,2,3-triazol-1-yl) salicylic acid derivatives.
served in 1H NMR spectra of compounds 4-17, whereas the corre-
sponding 13C NMR spectra reveal C-4 and C-5 triazole carbon sig-
Compound
R1
% Yield
nals at 143 and 112 ppm respectively. Some selected spectral data
of compounds triazoles 4-17 are summarized in Table 2.
4
5
6
7
CH2O(2,4-NO2)C6H3
CH2O(4-Br)C6H4
85
99
43
84
A noteworthy fact derived from MS analysis that should be con-
sidered to complete this spectroscopic information is the appear-
ance in most of mass spectra of specific ions at m/z 190 and at m/z
CH2O(3-iPr-5-CH3)C6H3
CH2O(2-OCH3-4-CHO)C6H3
172 which in some cases is presented as base peak. Two possible
fragmentation patterns to rationalize these peaks are showed in
Scheme 4. An ionization on triazole N1 followed by loss of RO /RS.
fragment generates a methylene triazolium ion 19 which in turn
.
8
9
64
89
68
46
CH2O(4-Cl)C6H4
1
1
0
1
CH2O(2-Cl)C6H4
loses HCO H to give radical cation 20 with m/z 172. Other plau-
2
CH2O(2-OCH3-4-COCH3)C6H3
sible fragmentation mechanism involves the well documented ex-
trusion of N2 from 1,2,3-triazole [30,31] affording azirinyl radical
cation 21 which undergoes a cleavage of RO-CH /RS-CH bond pro-
2
2
1
2
51
viding successively methylene azirinyl cations 22 (m/z 190) and 23
m/z 172) after losing of H O.
(
2
3
.2. Biological evaluation and Cytotoxic Activity
The anti-proliferative activity of compounds 4–17 was evaluated
1
1
3
4
66
84
against a series of tumoral cell lines which included U251 (human
glioblastoma), PC-3 (human prostate cancer cell line), K562 (hu-
man leukemia), HCT-15 (human colorectal adenocarcinoma), MCF-
7 (human breast adenocarcinoma) and SKLU (human lung adeno-
carcinoma), the results are summarized in Table 3.
Although a direct comparison among all these compounds is
not simple, some relationships can be found through an analysis
of compounds that share common structural features. Thus, in or-
der to facilitate this analysis, four groups of 4-(1,2,3-triazol-1-yl)
salicylic acid derivatives were considered according to a structural
similarity premise.
1
1
1
5
6
7
55
66
68
CH2O(4-CHO)C6H4
CH2O(2-CHO)C6H4
A first 4-(1,2,3-triazol-1-yl) salicylic acid group included phe-
noxymethyl derivatives substituted at C4 position on triazole moi-
ety (compounds 4-7, 9-11, 16 and 17). In general, these molecules
exhibit good activities for HCT-15, U251 and MCF-7, however, these
compounds are also toxic against COS7 healthy cells. The molecule
that displays the highest toxicity in this group is compound 6, with
64.64% cell growth inhibition against HCT-15 and 52.3 % inhibi-
tion against COS7 cell lines. This activity can be attributed to the
bioavailability provided by the m-cymene moiety present in several
natural products with well-known biological activity [32,33]. Other
interesting example from this triazole group is compound 4 bear-
ing a 2,4-dinitrophenyl fragment which probably causes the high
activity against HCT-15 (39.0 % cell growth inhibition) and also
against COS7 (30.6 %) due to the nitro group ability to interact with
biological nucleophiles such as proteins, amino acids, nucleic acids,
and enzymes through non-covalent interactions found in some an-
tineoplasic, antibiotic, and antiparasitic agents which contain this
group [34]. On the other hand, the aryl methoxy group together
with aldehyde/ketone carbonyl group present in molecules 11 and
7 promotes a low polarity effect and formation of non-covalent hy-
drogen interactions with carbonyl substituent increasing the cyto-
toxic activity observed in these compounds, 45.2% growth inhibi-
tion against PC-3 cells with compound 7, whereas compound 11
showed 32.85% growth inhibition against MCF-7 cells.
described by Dupuis [14] through a consecutive diazotization-
azidation process on 4-amino-2-hydroxybenzoic acid (Scheme 3).
A characteristic band at 2104 cm–1 corresponding to stretch-
ing N=N=N azide vibration [19] is present in the IR spectrum;
furthermore, carboxylic acid group was identified by the C=O
–
1
stretching vibration band at 1757 cm and a wide O-H stretching
band at 3600 cm–1; an additional O-H vibration band (3200 cm–1
)
corroborates salicylic acid arrange in agreement to previous re-
ports [20–22] which also describe a strong absorption peak found
approximately at 270 nm in the respective UV spectra.
Subsequent CuAAC reaction of azide 3 with the appropriate
alkynes in presence of catalytic amounts of CuI afforded the corre-
sponding 4-(1,2,3-triazol-1-yl) salicylic acid derivatives 4-17 in 43-
9
9% yields. The results in Table 1 illustrate the product yields and
the functional groups used on the alkyne part which integrate the
substituents at C5 position in obtained triazole rings.
Compounds 4-17 are quite stable in solution after 48 h, which is
important to know because these molecules are structural specifics
and there are not transformations in solution. The 1,2,3-triazole
moiety in these compounds was unambiguously determined by
the conventional spectroscopic techniques; for instance, IR spec-
tra of triazoles 4-17 exhibit the distinctive aromatic C=C stretch-
–
1
ing vibration band at 1600 cm together to a N=N band at 1450
cm 1 according to literature [23–26]. A remarkable absorption
−
An outstanding characteristic perceived in a second 4-(1,2,3-
triazol-1-yl) salicylic acid derivatives group is the existence of an
alicyclic part directly attached to the triazole ring bearing a cyclo-
hexanol fragment in compound 12 or a methylcyclopentanedione
moiety in compound 13, which resulted more active in this series
with 52.4% and 38.05% growth inhibition of U251 and HCT-15 cell
lines respectively, but also more toxic against healthy cells (47.4%
cell growth inhibition of COS7). This behavior could be related to
the chemical nature of the cyclopentanedione fragment present in
several biologically active natural products [35,36] as well as other
−
1
band detected in these spectra is located at 1300 cm which has
been correlated to a cyclic -N-N=N- configuration present in 1,2,3-
triazole core [27,28]. On the other hand, high energy absorption
bands ranged at 255-280 nm are present in UV spectra of com-
∗
pounds 4-17 which are assigned to a π → π transition in aro-
matic rings [29].
The presence of 1,2,3-triazole ring was categorically established
through the NMR spectra analysis. In this way, a typical singlet sig-
nal assigned to the hydrogen on triazole C-5 at 7.5-8.8 ppm is ob-

Z.G. Ríos-Malváez, M.-A. Cano-Herrera and J.C. Dávila-Becerril et al. / Journal of Molecular Structure 1225 (2021) 129149
7
Table 2
Selected spectral data of 4-(1,2,3-triazol-1-yl) salicylic acid derivatives.
IR (νmax, cm 1)
−
1H NMR (ppm)
13 C NMR (ppm)
Compound
λ
max
log
ε
C=Carom
N=Narom
-N-N=N-
Triazole C5-H
C4
C5
4
5
6
7
8
9
256
255
257
273
274
273
273
270
257
256
0.090
0.101
0.315
0.045
0.400
0.053
0.052
0.226
0.461
0.023
0.201
0.032
0.218
0.208
0.324
1600
1600
1600
1640
1610
1600
1600
1590
1620
1605
1480
1450
1450
1470
1450
1480
1440
1490
1440
1440
1300
1287
1290
1265
1300
1310
1295
1270
1300
1305
8.04
8.49
7.99
8.88
7.86
7.54
7.52
7.55
7.93
7.89
139.7
143.4
144.5
142.8
144.9
143.8
146.4
143.4
141.4
143.4
115.2
112.4
112.2
112.6
110.0
110.3
107.7
112.3
109.9
108.9
1
1
1
1
0
1
2
3
2
70
1
1
1
1
4
5
6
7
281
256
273
273
1680
1610
1600
1600
1460
1450
1480
1485
1330
1290
1300
1280
7.99
7.91
7.53
7.54
140.0
143.3
143.5
143.9
108.7
110.1
110.3
110.0
Table 3
Growth inhibition (%) of tumor cell lines at 25 μM by compounds 4-17a
Compound
U251
PC-3
K562
HCT-15
MCF-7
SKLU-1
COS7
4
5
6
7
8
9
18.28
12.0
23.43
4.4
NCb
9.9
NC
45.2
3.9
9.1
NC
NC
NC
NC
NC
NC
NC
NC
9.0
39.03
26.53
64.64
26.56
67.63
16.3
20.6
17.3
10.5
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
30.61
16.9
52.3
20.3
44.28
2.5
18.1
13.56
9.4
20.45
2.5
15.23
12.7
4.2
20.41
11.8
3.5
1
1
1
1
1
1
1
1
0
1
2
3
4
5
6
7
NC
19.1
5.0
10.66
11.01
52.4
11.55
57.9
4.66
6.78
10.21
3.6
10.57
17.21
38.05
10.93
35.24
6.25
32.85
23.23
11.69
33.53
NC
9.13
5.26
47.4
14.67
47.64
3.96
8.71
13.9
4.86
5.51
NC
12.82
20.41
1.28
8.97
a
The values indicate the mean calculated from experiments conducted in triplicate.
NC: not cytotoxic.
b
similar nitrogen 5-membered rings such as pyrrole and phthalim-
ide analogs used as anticancer agents [37]. Moreover, this observed
activity can also be boosted by the potential ability of compound
in their structures. From this group, benzaldehyde derivatives re-
vealed activity against MCF-7, 20.41 and 12.82% cell growth inhibi-
tion respectively for 17 and 16 besides low toxicity against COS7
cells (8.71 and 3.96 % cell growth inhibition for compounds 17
and 16 respectively). In this case, the aldehyde substituent clearly
plays a relevant role in the triazole activity which is almost dupli-
cated by changing the position in the aromatic ring from 4- to 2-,
this behavior is also reflected in the toxicity of these compounds
against healthy cells. The cytotoxic activity of this pair of com-
pounds contrasts to observed activity in compounds 5, 9 and 10
which produce 26.53, 16.3 and 19.1 % growth inhibition into HCT-
15 cells similar to aldehyde derivatives discussed above and con-
siderably less active than triazoles classified in other series. How-
ever, a promising molecule in this group is triazole 10 which ex-
hibits 19.1 % cell growth inhibition against HCT-15 cancer cells and
low toxicity with healthy COS7 cells (5.0 %). In addition, this com-
pound is quite selective showing no activity against U251, PC-3 and
SKLU-1 cancer cell lines, and just a reduced toxicity with K562 (4.2
%) and MCF-7 (3.5 %) cancer cells, which is apparently associated
with o- position between substituents in aromatic ring identified
in other molecules with this substitution pattern and similar activ-
ity. Although this work is not conclusive, it provides several lines
that should be explored, some of which are currently under devel-
opment in our research group.
13 to promote non-covalent interactions in physiologic media due
to the presence of the two bioavailable ketone groups. These com-
pounds are interesting; however, their toxicity against healthy cells
reduces their potential attractiveness for further studies.
Group 3 of 4-(1,2,3-triazol-1-yl) salicylic acid derivatives com-
prises heterocyclic rings attached to 1,2,3-triazole moiety through
a -SCH2- linkage, these heterocycles include pyrimidine in com-
pound 8, benzothiazole (14) and benzimidazole (15) which would
incorporate the well-known biological activities from these hetero-
cyclic fragments to final molecules. The results of cytotoxic activ-
ity show that compounds 8 and 15 are highly active against HCT-
15 (67.63 and 35.24 % respectively) but at the same time these
molecules display high toxicity to COS7 cells (44.28 and 47.64 %
respectively) as well as other groups discussed above. A notewor-
thy property found in compound 14 is the selective activity against
MCF-7 cell line (33.53 % cell growth inhibition) in contrast to ac-
tivity against HTC-15 and COS7 (10.93 and 14.67% cell growth in-
hibition respectively). On the other hand, triazole 15 proved to be
the most active compound of this series, showing 57.9 % growth
inhibition of U251 cells, 35.24 % growth inhibition of HCT-15 and
47.64 % growth inhibition of COS7 cells. This feature could drive
next investigations to study the effect of substituents in benzimi-
dazole core on antitumoral activity of this kind of molecules.
A fourth group of triazoles involves compounds 5, 9, 10, 16 and
Inhibitory activity showed by compounds 4-17 is comparable
to some 1,2,3-triazole-based tumor cell growth inhibitors [38–45].
This feature opens the possibility of considering 4-(1,2,3-triazol-
1-yl) salicylic acid derivatives as an emerging group of STAT3 in-
17 holding halogen atoms and aldehyde/ketone carbonyl groups

8
Z.G. Ríos-Malváez, M.-A. Cano-Herrera and J.C. Dávila-Becerril et al. / Journal of Molecular Structure 1225 (2021) 129149
Fig. 2. Intermolecular interactions between 6 and SH2.
Fig. 1. Docking interaction energies by domain.
hibitors together to other small molecules [46–49]. Accordingly,
further studies will be necessary to modify biological activity pro-
viding higher selectivity in terms of a cytotoxic activity increase
against specific cancer lines with low impact to healthy cells in-
cluding intensive studies on antiproliferative activity against tumor
renewal [50]. These challenges might be overcome through the use
of the Click Chemistry approach due to this concept would allow
an easy biological activity modulation by a simple functional group
exchange in alkyne fragment; these are some advantages of using
1,2,3-triazole moiety as a versatile scaffold, besides possessing a
metal coordination ability which gives an additional chance to ex-
tend inhibitory potency such as Kandioller and coworkers have ob-
served [51].
Fig. 3. Non-covalent interactions between 6 and predicted N-Terminal binding site.
The H-bonds between the carboxylate of the salicylate group and the amino acids
are shown in blue.
3
.3. Molecular modeling
All optimized geometries show an intramolecular H-bond in the
salicylate fragment. The structures are enough rigid by not showing
any additional intramolecular interactions. STAT3 protein is one of
the most studied cancer-related factors, being modeled by classical
molecular dynamics and molecular docking [52] and also docking
calculations for inhibit the STAT3 dimerization [53], however, there
was none work with triazole-derivatives as a STAT3 inhibitors.
A blind molecular docking was carried out into both SH2 and
N-terminal domains. Most of the molecules show a high affinity to
N-terminal domain, such as the delta G binding energy is in the
range from 6.3 to 7.9 kcal/mol, but for the SH2 domain the delta G
binding energy range is from 6.4 to 7.5 kcal/mol (Fig. 1). By com-
paring binding energies, only four compounds show more affinity
for the SH2 domain, and two show the same binding energy for
the SH2 and N-terminal domains, which means that compounds
are non-selective through the STAT3 principal domains.
Other representative intermolecular interaction displayed with
SH2 domain involves H-bonds between the SER-158-backbone
residue and R fragment as well as steric interactions with SER-164
residue. In addition, an interaction with the triazole fragment and
ARG-154 residue is also detected.
For N-Terminal domain, all models include H-bonds between
salicylate fragment and amino acids, like in SH2 model, with GLN-
3 and with SER-113. The compound that showed the best affin-
ity by energy binding with N-terminal domain is 6 (Fig. 3), but
the protein-ligand interactions shown on docking are only two H-
bonds: one between the salicylate and the GLN-3, the salicylate
and LEU-109 and a Van Der Waals interaction between the triazole
and ALA-44. This means that the H-bonds are quite strong to bind
the ligand consistent with experimental inhibition results and the
Van Der Waals interaction is not affecting the binding mode by a
repulsive interaction one.
The best binding models were chosen from each domain, two
for SH2 domain and three for N-Terminal domain. In both domains
are shown hydrogen bonds between the amino acids in the binding
site and the compounds synthesized in this work. For SH2 domain,
compounds 4 and 6 represent the best binding models, whereas
for the N-Terminal domain, 6, 12 and 13 are the best binding mod-
els.
Steric interactions are also important between 4 and N-Terminal
binding site. As shown in Fig. 3, the salicylate ring interacts with
the LEU-109 sidechain. On the studied models there are strong H-
bonds between the salicylate group and the amino acid sidechains
(Fig.s 4 and 5).
For SH2 domain, compound 6 shows hydrogen bonds, also
π-stacking between the salicylate ring and the PHE-191 residue
H-bond interactions between salicylate fragment and amino
acids in both domains are constant and consistent in all binding
sites given by the blind docking, but also π-stacking interactions
are present on many of the chosen models. These interactions are
quite strong to explain experimental biological activity. Therefore,
(
Fig. 2). The carboxylate group from salicylate ring is H-bond ac-
ceptor and donor with the surrounding amino acids, such as ASN-
85 and the GLY-190 residues.
1

Z.G. Ríos-Malváez, M.-A. Cano-Herrera and J.C. Dávila-Becerril et al. / Journal of Molecular Structure 1225 (2021) 129149
9
Declaration of Competing Interest
The authors declare that they have no known competing finan-
cial interests or personal relationships that could have appeared to
influence the work reported in this paper.
CRediT authorship contribution statement
Zita G. Ríos-Malváez: Methodology, Investigation. Ma-Angeles
Cano-Herrera: Methodology, Investigation. Juan Carlos Dávila-
Becerril: Software, Investigation. Gustavo Mondragón-Solórzano:
Software, Data curation, Writing - original draft, Writing - re-
view
&
editing. María Teresa Ramírez-Apan: Methodology,
original
Formal analysis. David Morales-Morales: Writing
-
draft, Formal analysis. Joaquín Barroso-Flores: Data curation,
Investigation. Jonnathan G. Santillán-Benítez: Conceptualiza-
tion. M.V. Basavanag Unnamatla: Investigation, Methodology.
Marco Antonio García-Eleno: Formal analysis, Validation, Data
curation. Nelly González-Rivas: Methodology, Investigation, For-
mal analysis, Validation. Erick Cuevas-Yañez: Conceptualization,
Supervision, Project administration, Funding acquisition, Writing -
original draft, Writing - review & editing.
Fig. 4. Intermolecular interactions between 12 and N-Terminal domain. H-bond in-
teractions are shown in blue.
Acknowledgments
Financial support from CONACYT (project No. A1-S-18230 and
fellowships for ZGRM, CVU: 860116, and GMS, CVU: 771371) is
gratefully acknowledged. The authors would like to thank N.
Zavala, A. Nuñez, L. Triana and M. C. Martínez for the technical
support. JCDB, GMS and JBF want to thank to Dr. Jacinto Sandoval
for the academic assessment into the geometry optimizations.
Supplementary materials
Supplementary material associated with this article can be
found, in the online version, at doi:10.1016/j.molstruc.2020.129149.
Fig. 5. Non-covalent interactions between 13 and N-Terminal domain. The H-bonds
are shown in blue.
References
[
1] D.P. Ball, A.M. Lewis, D. Williams, D. Resetca, D.J. Wilson, P.T. Gunning, Signal
transducer and activator of transcription 3 (STAT3) inhibitor, S3I-201, acts as a
potent and non-selective alkylating agent, Oncotarget 7 (2016) 20669.
molecular docking calculations suggest a non-selective binding site
between domains due to the similar binding energies in both SH2
and N-terminal domains.
[2] R. Fagard, V. Metelev, I. Souissi, F. Baran-Marszak, STAT3 inhibitors for cancer
therapy, JAK-STAT 2 (2013) e22882.
As far we know, these are the first examples of 1,2,3-triazolyl
compounds derived from 4-amino salicylic acid displaying anti-
cancer activity and providing new opportunities to design and syn-
thesize more STAT 3 inhibitors, either as antitumor agents them-
selves or as a part of a combined therapy [54].
[
3] K. Matsuno, Y. Masuda, Y. Uehara, H. Sato, A. Muroya, O. Takahashi, T. Yokota-
gawa, T. Furuya, T. Okawara, M. Otsuka, N. Ogo, T. Ashizawa, C. Oshita, S. Tai,
H. Ishii, Y. Akiyama, A. Asai, Identification of a New Series of STAT3 Inhibitors
by Virtual Screening, ACS Med. Chem. Lett. 1 (2010) 371–375.
4] D. Bhasin, K. Cisek, T. Pandharkar, N. Regan, C. Li, B. Pandit, J. Lin, P.K. Li., De-
sign, synthesis, and studies of small molecule STAT3 inhibitors, Bioorg. Med.
Chem. Lett. 18 (2008) 391–395.
[
[
[
5] C.H. Teng, S.J. Won, C.H. Lin, Design, synthesis and cytotoxic effect of hydroxy
and 3-alkylaminopropoxy-9,10-anthraquinone derivatives, Bioorg. Med. Chem.
4. Conclusions
13 (2005) 3439–3445.
6] J.A. Drewry, S. Fletcher, P. Yue, D. Marushchak, W. Zhao, S. Sharmeen, X. Zhang,
A.D. Schimmer, C. Gradinaru, J. Turkson, PT. Gunning, Coordination complex
SH2 domain proteomimetics: an alternative approach to disrupting oncogenic
protein–protein interactions, Chem. Commun. 46 (2010) (2010) 892–894.
7] B.D.G. Page, D.C. Croucher, Z. Li, Y.L. Wong, S. Haftchenary,
V.H. Jimenez-Zepeda, J. Atkinson, P.A. Spagnuolo, R. Colagouri, A.M. Lewis,
A.D. Schimmer, S. Trudel, P.T. Gunning, Inhibiting Aberrant Signal Transducer
and Activator of Transcription (STAT) Protein Activation with Tetrapodal, Small
Molecule Src Homology 2 domain binders: Promising Agents Against Multiple
Myeloma, J. Med. Chem. 56 (2013) 7190–7200.
In brief, CuAAC reaction demonstrated to be a useful method
in the preparation of a collection of 4-(1,2,3-triazol-1-yl) salicylic
acid derivatives with outstanding specific activity against some tu-
moral cell lines. According to experimental data, the theoretical re-
sults show that the interactions are crucial into the molecular in-
hibition of the SH2 and N-terminal domains of STAT3. The strong
H-bond interactions between N-terminal, SH2 domain and ligand
show that the synthesized compounds are non-selective between
STAT3 domain; instead, a strong interaction between ARG-154 and
the triazole fragment is observed which can probably be associ-
ated to cytotoxic activity in these molecules. The simplicity of syn-
thetic methods and anticancer activities found in some compounds
suggests that this class of 4-(1,2,3-triazol-1-yl) salicylic acid deriva-
tives will enjoy a widespread application.
[
[8] S. Fletcher, B.D.G. Page, X. Zhang, P. Yue, Z.H. Li, S. Sharmeen, J. Singh,
W. Zhao, A.D. Schimmer, S. Trudel, J. Turkson, P.T. Gunning, Antagonism of
the Stat3–Stat3 Protein Dimer with Salicylic Acid Based Small Molecules,
ChemMedChem 6 (2011) 1459–1470.
[9] S. Fletcher, J. Singh, X. Zhang, P. Yue, B.D.G. Page, S. Sharmeen, V.M. Shahani,
W. Zhao, A.D. Schimmer, J. Turkson, P.t. Gunning, Disruption of Transcription-
ally Active Stat3 Dimers with Nonphosphorylated, Salicylic Acid-Based Small
Molecules: Potent in vitro and Tumor Cell Activities, ChemBioChem 10 (2009)
1959–1964.

10
Z.G. Ríos-Malváez, M.-A. Cano-Herrera and J.C. Dávila-Becerril et al. / Journal of Molecular Structure 1225 (2021) 129149
[
10] E. Bonandi, M.S. Christodoulou, G. Fumagalli, D. Perdicchia, G. Rastelli, D. Pas-
[33] A. Marchese, C.E. Arciola, R. Barbieri, A. Sanches Silva, S.F. Nabavi, A.J.T. Sokeng,
M. Izadi, N.J. Jafari, I. Suntar, M. Daglia, S.M. Nabavi, Update on monoterpenes
as antimicrobial agents: a particular focus on p-Cymene, Materials 10 (2017)
947.
sarella, The 1,2,3-triazole ring as a bioisostere in medicinal chemistry, Drug
Discov. Today 22 (2017) 1572–1581.
[
11] P. Thirumurugan, D. Matosiuk, K. Jozwiak, Click chemistry for drug devel-
opment and diverse chemical−biology applications, Chem. Rev. 113 (2013)
[34] S.N.J. Moreno, R. Docampo, Mechanism of toxicity of nitro compounds used
in the chemotherapy of trichomoniasis, Environ. Health Persp. 64 (1985)
199–208.
[35] T.J. Maimone, P.S. Baran, Modern synthetic efforts toward biologically active
terpenes., Nat. Chem. Biol 3 (2007) 396–407.
4
905–4979.
[
12] S. Haider, M.S. Alam, H. Hamid, 1,2,3-Triazoles: scaffold with medicinal signif-
icance, Inflammation Cell Signal. 1 (2014) e95.
[
13] S.G. Agalave, S.R. Maujan, V.S. Pore, Click Chemistry: 1,2,3-Triazoles as Pharma-
cophores, Chem. Asian J. 6 (2011) 2696–2718.
[36] C. Thirsk, A. Whiting, Polyene natural products, J. Chem. Soc., Perkin Trans. 1
(2002) 999–1023.
[
14] G. Dupuis, An asymmetrical disulfide-containing photoreactive heterobifunc-
tional reagent designed to introduce radioactive labeling into biological recep-
tors, Can. J. Chem. 65 (1987) 2450–2453.
[37] R. Kaur, V. Rani, V. Abbot, Y. Kapoor, D. Konar, K. Kumar, Recent synthetic and
medicinal perspectives of pyrroles: An overview, J. Pharm. Chem. Chem. Sci. 1
(2017) 17–32.
[
15] A. Monks, D. Scudiero, P. Skehan, R. Shoemaker, K. Paul, D. Vistica, C. Hose,
J. Langley, P. Cronise, A. Vaigro-Wolff, M. Gray-Goodrich, H. Campbell, J. Mayo,
M. Boyd, Feasibility of a High-Flux Anticancer Drug Screen Using a Diverse
Panel of Cultured Human Tumor Cell Lines, J. Natl. Cancer I. 83 (1991)
[38] I.I. Sahay, P.S. Ghalsasi, Synthesis of New 1,2,3-triazole Linked Benzimidazole
Molecules as Anti-Proliferative Agents, Synth. Commun. 47 (2017) 825–834.
[39] N. Pokhodylo, O. Shyyka, V. Matiychuk, Synthesis of 1,2,3-Triazole Derivatives
and Evaluation of their Anticancer Activity, Sci. Pharm. 81 (2013) 663–676.
[40] M.S. Sonego, N.V. Segatto, L. Damé, M. Fronza, C.B. Gomes, T.L. Oliveira,
F.K. Seixas, L. Savegnago, K.M. Schachtschneider, D. Alves, T. Collares, 7-Chloro-
quinoline-1,2,3-triazoyl carboxamides induce cell cycle arrest and apoptosis in
human bladder carcinoma cells, Invest. New Drug. 38 (2020) 1020–1030.
[41] T.M. Queiroz, E.V.M. Orozco, V.R. Silva, L.S. Santos, M.B.P. Soares, D.P. Bez-
erra, A.L.M. Porto, Semi-synthesis of β-keto-1,2,3-triazole derivatives from
757–766.
[
16] G.M.J. Frisch, W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman,
G. Scalmani, V. Barone, B. Mennucci, G.A. Petersson, H. Nakatsuji, M. Caricato,
X. Li, H.P. Hratchian, A.F. Izmaylov, J. Bloino, G. Zheng, J.L. Sonnenberg, Gaus-
sian 09, Revision E.01, Gaussian, Inc., Wallingford, CT, 2009.
[
17] N. El-Hachem, B. Haibe-Kains, A. Khalil, F.H. Kobeissy, G. Nemer, in: AutoDock
and AutoDockTools for protein-ligand docking: Beta-site amyloid precursor
protein cleaving enzyme 1(BACE1) as a case study, in Neuroproteomics. Meth-
ods in Molecular Biology, vol. 1598, Humana Press, New York, NY, 2017,
pp. pp.391–pp.403.
ethinylestradiol and evaluation of the cytotoxic activity, Heliyon
e02408.
5 (2019)
[42] P. de Andrade, A.F. Dias, F. Figueiro, F.C. Torres, D.F. Kawano, A.M.O. Battastini,
I. Carvalho, C.H.T.P. da Silva, J.M. Campos, 1,2,3-Triazole tethered 2-mercapto-
benzimidazole derivatives: design, synthesis and molecular assessment toward
C6 glioma cell line, Future Med. Chem. 12 (2020) 689–708.
[
[
18] J.M. Solano-Altamirano, J.M. Hernández-Pérez, DensToolKit: A comprehensive
open-source package for analyzing the electron density and its derivative
scalar and vector fields, Comput. Phys. Commun. 196 (2015) 362–371.
19] R.
H.
López-González,
Reyes, N.
J.
Bautista-Renedo,
D.
Martínez-Otero,
1,4- and
[43] I.C. Chipoline, E. Alves, P. Branco, L.V. Costalotufo, V.F. Fer-
González-Rivas,
E.
Cuevas-Yañez,
reira,
F.C.
Da
Silva,
Synthesis
and
Cytotoxic
Evaluation
of
1
,5-di(N-phthalimidomethyl)-1,2,3-triazoles: crystal structures and density
functional theory studies of the alkyne and azide precursors, J. Chem. Res. 40
2016) 308–313.
1H-1,2,3-Triazol-1-ylmethyl-2,3-dihydronaphtho[1,2-b]furan-4,5-diones, Anais
da Academia Brasileira de Ciências 90 (1 Suppl. 2) (2018) 1027–1033.
[44] I.C. Chipoline, A.C.C. da Fonseca, G.R.M. da Costa, M.P. de Souza, V.W.H. Ra-
belo, L.N. de Queiroz, T.L.F. de Souza, E.C.P. de Almeida, P.A. Abreu, B. Pontes,
V.F. Ferreira, F.C. da Silva, B.K. Robbs, Molecular mechanism of action of new
1,4-naphthoquinones tethered to 1,2,3-1h-triazoles with cytotoxic and selective
effect against oral squamous cell carcinoma, Bioorg. Chem. 101 (2020) 103984.
[45] Y. Jia, M. Li, Y. Cao, W. Feng, X. Li, W. Xue, H. Shi, Discovery of a Novel Ben-
zenesulfonamide Analogue That Inhibits Proliferation and Metastasis Against
Ovarian Cancer OVCAR-8 Cells, Drug. Des. Dev. Ther. 14 (2020) 207–216.
[46] Z. Liu, X. Ge, Y. Gu, Y. Huang, H. Liu, M. Yu, Y. Liu, Small molecule STAT3 in-
hibitor, 6Br-6a suppresses breast cancer growth in vitro and in vivo., Biomed.
Pharmacother. 121 (2020) 109502.
(
[
20] M.J.M. Takac, D.V. Topic, FT-IR and NMR spectroscopic studies of salicylic acid
derivatives. II. Comparison of 2-hydroxy- and 2,4- and 2,5-dihydroxy deriva-
tives, Acta Pharm 54 (2004) 177–191.
21] M.K. Trivedi, A. Branton, D. Trivedi, H. Shettigar, K. Bairwa, S. Jana, Fourier
Transform Infrared and Ultraviolet-Visible Spectroscopic Characterization of
Biofield Treated Salicylic Acid and Sparfloxacin, Nat. Prod. Chem. Res. 3 (2015)
[
1000186.
[
22] S. Suresh, S. Gunasekaran, S. Srinivasan, Spectroscopic (FT-IR, FT-Raman, NMR
and UV–Visible) and quantum chemical studies of molecular geometry, Fron-
tier molecular orbital, NLO, NBO and thermodynamic properties of salicylic
acid, Spectrochim. Acta Part A 132 (2014) 130–141.
[47] L. Yang, S. Lin, L. X, J. Lin, C. Zhaob, X. Huang, Novel activators and small–
molecule inhibitors of STAT3 in cancer, Cytokine Growth Factor Rev. 49 (2019)
10–22.
[
23] M. Bellagamba, L. Bencivenni, L. Gontrani, L. Guidoni, C. Sadun, Tautomerism in
liquid 1,2,3-triazole: a combined Energy-Dispersive X-Ray Diffraction, Molecu-
lar Dynamics and FTIR study, Struct. Chem 24 (2013) 933–943.
24] F. Billesa, H. Endredi, Keresztury. Vibrational spectroscopy of triazoles and
tetrazole, THEOCHEM 530 (2000) 183–200.
25] S.T. Abu-Orabi, M.A. Atfah, I. Jibril, F.M. Marii, A.A.S. Ali, Dipolar Cycloaddition
Reactions of Organic Azides with some Acetylenic Compounds, J. Heterocycl.
Chem. 26 (1989) 1461–1468.
26] C.N.R. Rao, R. Venkataraghavan, Contribution to the Infrared Spectra of
Five-Membered N- and N,S-Heterocyclic Compounds, Can. J. Chem. 42 (1964)
[48] P. Yue, J. Turkson, Targeting STAT3 in cancer: how successful are we? Expert
Opin, Investig. Drugs 18 (2009) 45–56.
[
[49] Y. Tsujita, A. Horiguchi, S. Tasaki, M. Isono, T. Asano, K. Ito, T. Asano, Y. Mayumi,
T. Kushibiki, STAT3 inhibition by WP1066 suppresses the growth and invasive-
ness of bladder cancer cells, Oncol. Rep. 38 (2017) 2197–2204.
[
[50] F. Barbieri, S. Thellung, A. Ratto, E. Carra, V. Marini, C. Fucile, A. Bajetto, A. Pat-
tarozzi, R. Würth, M. Gatti, C. Campanella, G. Vito, F. Mattioli, A. Pagano,
A. Daga, A. Ferrari, T. Florio, In vitro and in vivo antiproliferative activity of
metformin on stem-like cells isolated from spontaneous canine mammary car-
cinomas: translational implications for human tumors, BMC Cancer 15 (2015)
228.
[
43–49.
[
27] E. Lieber, C.N.R. Rao, T.S. Chao, H. Rubinstein, The Ultraviolet and Infrared
Spectra of Vicinal-Triazole Derivatives, Chem 36 (1958) 1441–1443.
[
28] J.A.C. Allison, H.S. El-Khadem, C.A. Wilson, Chloropalladation of
[51] C.A. Riedl, L.S. Flocke, M. Hejl, A. Roller, M.H.M. Klose, M.A. Jakupec, W. Kan-
dioller, B.K. Keppler, Introducing the 4-Phenyl-1,2,3-Triazole Moiety as a Ver-
satile Scaffold for the Development of Cytotoxic Ruthenium(II) and Osmium(II)
Arene Cyclometalates, Inorg. Chem. 56 (2017) 528–541.
[52] F.S. Zariquiey, J.V. Da Souza, R. Estrada-Tejedor, A.K. Bronowska, If you can-
not win them, join them: understanding new ways to target stat3 by small
molecules, ACS Omega 4 (2019) 13913–13921.
2
-phenyl-1,2,3-triazoles as means of selective o-chlorination, J. Hetero-
a
cycl. Chem. 12 (1975) 1275–1277.
[29] Y. Tanaka, S.R. Velen, S.I. Miller, Syntheses and Properties of H-1,2,3-Triazoles,
Tetrahedron 29 (1973) 3271–3283.
[
30] S.I. Miller, R.R. Lii, Y. Tanaka, Mass Spectra of 1,2,3-Triazoles, J. Chem. Soc.,
Perkin Trans. 1 (1979) 15–19.
[
31] A. Maquestiau, Y. Van Haverbeke, M. Willame, M. Begtrup, Fragmentation des
- et 5-hydroxy -1,2,3-triazoles sous l’impact electronique, Bull. Soc. Chim.
Belg. 85 (1976) 795–800.
[53] M.A. Al Noman, T. Hossain, M. Ahsan, S. Jamshidi, C.M. Hasan, K.M. Rahman,
Crispenes F and G, cis-Clerodane Furanoditerpenoids from Tinospora crispa, In-
hibit STAT3 Dimerization, J. Nat. Prod. 81 (2018) 236–242.
4
[
32] C. Atef, M. Boualem, M.M. Cherif, H. Youcef, C. Azzedine, Chemical composition
and antimicrobial activity of essential oils in Xerophytic plant Cotula cinerea
Del (Asteraceae) during two stages of development: flowering and fruiting, J.
Appl. Pharm. Sci. 5 (2015) 29–34.
[54] T. Ashizawa, A. Iizuka, C. Maeda, E. Tanaka, R. Kondou, H. Miyata, T. Sugino,
T. Kawata, S. Deguchi, K. Mitsuya, N. Hayashi, A. Asai, M. Ito, K. Yamaguchi,
Y. Akiyama, Impact of combination therapy with anti-PD-1 blockade and a
STAT3 inhibitor on the tumor-infiltrating lymphocyte status, Immunol. Lett.
216 (2019) 43–50.