SBA-Pr-SO3H-catalyzed synthesis of bispyrazole compounds as anti-bacterial agents and inhibitors of phosphorylated RET tyrosine kinase

Article abstract of DOI:10.1007/s13738-019-01618-1

Pyrazolone was prepared through the reaction of ethyl acetoacetate and hydrazine hydrate in EtOH at room temperature. Then, bispyrazole derivatives, as attractive biologically active compounds, were synthesized by reacting two equivalents of prepared pyrazolone and one equivalent of aldehyde in the presence of SBA-Pr-SO₃H under solvent-free condition at 120?°C. The reaction time was short (3–6?min), while the products’ yield was high (85–97%). Discovery Studio 2.5 (Accelrys Inc, San Diego, CA, USA) was employed to dock the compounds to protein. Molecular docking (GOLD method) studies suggested that pyrazoles bind efficiently to RET kinase. Next, biological activities of the bispyrazoles were tested against some Gram-positive and Gram-negative bacteria and for antifungal activity via the disc-diffusion method. All compounds showed no significant anti-bacterial activities, but two of them showed good activities against Candida albicans. Graphical abstract: [Figure not available: see fulltext.]

Full text of DOI:10.1007/s13738-019-01618-1

Journal of the Iranian Chemical Society
https://doi.org/10.1007/s13738-019-01618-1
ORIGINAL PAPER
SBA-Pr-SO H-catalyzed synthesis of bispyrazole compounds as anti-
3
bacterial agents and inhibitors of phosphorylated RET tyrosine kinase
1
1
1
2
2
Ghodsi Mohammadi Ziarani · Fatemeh Saidian · Parisa Gholamzadeh · Alireza Badiei · Jahan B. Ghasemi ·
2
3
Elham Aghaee · Ali Abolhasani Soorki
Received: 26 September 2018 / Accepted: 23 January 2019
Iranian Chemical Society 2019
©
Abstract
Pyrazolone was prepared through the reaction of ethyl acetoacetate and hydrazine hydrate in EtOH at room temperature.
Then, bispyrazole derivatives, as attractive biologically active compounds, were synthesized by reacting two equivalents of
prepared pyrazolone and one equivalent of aldehyde in the presence of SBA-Pr-SO H under solvent-free condition at 120 °C.
3
The reaction time was short (3–6 min), while the products’ yield was high (85–97%). Discovery Studio 2.5 (Accelrys Inc,
San Diego, CA, USA) was employed to dock the compounds to protein. Molecular docking (GOLD method) studies sug-
gested that pyrazoles bind efficiently to RET kinase. Next, biological activities of the bispyrazoles were tested against some
Gram-positive and Gram-negative bacteria and for antifungal activity via the disc-diffusion method. All compounds showed
no significant anti-bacterial activities, but two of them showed good activities against Candida albicans.
Graphical abstract
Keywords Bispyrazole · Green synthesis · Heterogeneous catalyst · Antifungal activity · GOLD method
Introduction
Electronic supplementary material The online version of this
article (https://doi.org/10.1007/s13738-019-01618-1) contains
supplementary material, which is available to authorized users.
Nitrogen-rich heterocycles are interesting compounds in
chemistry, biochemistry, and pharmacology. Among them,
pyrazole-annulated heterocyclic systems are important privi-
leged structures due to their special biological activities [1]
such as anti-inflammatory [2], analgesic [2], anti-tumor [3],
anti-microbial [4], anxiolytic [5], and antitubercular [6]
activities. Furthermore, pyrazole-containing natural prod-
ucts are widely found in plants and animals, for example,
β-pyrazol-1-yl-l-alanine and 4′-hydroxywithasomnine are
*
Ghodsi Mohammadi Ziarani
gmziarani@hotmail.com; gmohammadi@alzahra.ac.ir
1
2
3
Department of Chemistry, Alzahra University, Vanak
Square, P.O. Box 1993893973, Tehran, Iran
School of Chemistry, College of Science, University
of Tehran, Tehran 14155-6455, Iran
Research Institute of Applied Sciences, ACECR, Shahid
Beheshti University, Tehran, Iran
Vol.:(0
1
123456789)
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Journal of the Iranian Chemical Society
extracted from watermelon (Citrullus vulgaris) and New-
bouldia laevis, respectively (Fig. 1) [7, 8].
Synthesis of bispyrazole compounds 5a‑i
The modified Santa Barbara Amorphous (SBA-15) with
A mixture of aldehyde derivative 4 (1 mmol) and pyra-
propyl sulfonic acid groups (SBA-Pr-SO H) is a solid acid
zolone 3 (2 mmol, 0.196 g) and activated SBA-Pr-SO H
3
3
mesoporous compound which has been recently considered
as an efficient catalyst [9]. It is prepared through treating
with 3-mercaptopropyl trimethoxysilane with the free silanol
groups on the surface of crude SBA-15 to gain SBA-15
including propyl thiol groups (SBA-Pr-SH) following oxida-
tion of the thiol group by H O [10]. So far, various organic
(0.02 g) was stirred and heated under solvent-free con-
dition at 120 °C. After completion of the reaction, as
indicated by TLC, the crude product was dissolved in hot
EtOH and subsequently filtered for removal of the catalyst.
The pure products (5a-i) were obtained after cooling of
the filtrates. The spectral data for the new compounds are
given below.
2
2
compounds were synthesized by SBA-Pr-SO H, including
3
alcohols [11], isoindigo derivatives [12], imidazoles [13],
pyrano- and pyrido-pyrimidines [14, 15], quinazolinones
[
16], isatinhydrazones [17] and also used in the protection
4,4′‑((4‑Fluorophenyl)methylene)
bis(3‑methyl‑1H‑pyrazol‑5‑ol) (5g)
of carbonyl compounds [18], which shows its potential for
catalyzing organic syntheses. Herein, we want to describe
1
the catalytic activity of SBA-Pr-SO H in the preparation of
White powder (yield 97%); mp: 200–202 °C; H NMR
3
bispyrazole compounds.
(250 MHz, DMSO-d ): 2.05 (s, 6H), 4.80 (s, 1H), 6.97 (d,
6
1
3
2
H), 7.09 (d, 2H), 11.30 (br., 4H); C NMR (62.5 MHz,
DMSO-d ): 10.77, 32.54, 104.60, 114.55, 129.58,
6
−
1
Materials and methods
140.06,158.94,161.44,162.77; FT-IR (KBr) (ν /cm ):
max
3
205, 2930, 2400–3500, 1603, 1510, 1463, 1247, 1178,
Melting points were measured using the capillary tube
method with an electro-thermal 9200 apparatus. FT-IR spec-
tra were recorded from KBr disk using an FT-IR Bruker
1080, 1033, 980, 898, 822. Anal. Calcd. for C H FN O
15 15 4 2
(302.12): C 59.60, H 5.00, N 18.53, O 10.58, F 6.28;
Found: C 59.56, H 5.05, N 18.49.
1
13
Tensor 27 instrument. The H and C NMR were run on
a 250 and 62.5 MHz Bruker, respectively. Discovery Stu-
dio 2.5 (Accelrys Inc, San Diego, CA, USA) was employed
to dock the compounds to protein. The minimum inhibi-
tory concentration (MIC) was determined by microdilution
method and the results were compared with the commercial
chloramphenicol, gentamicine, and nystatin.
4,4′‑((3‑Methoxyphenyl)methylene)
bis(3‑methyl‑1H‑pyrazol‑5‑ol) (5h)
1
Yellow powder (yield 95%); mp: 266–268 °C; H NMR
(250 MHz, DMSO-d ): 2.05 (s, 6H), 3.99 (s, 3H), 4.77 (s,
6
1
3
1
H), 6.47–7.14 (4H), 11.10 (br., 4H); C NMR (62.5 MHz,
Synthesis and functionalization of SBA‑15
DMSO-d ): 10.80, 33.21, 55.23, 104.56, 110.47, 114.46,
6
1
20.44, 129.14, 140.19, 145.52, 159.41,161.46., FT-IR
−
1
The mesoporous SBA-15 was prepared and functionalized
according to our previous report, and then, the obtained
(KBr) (ν /cm ): 3205, 2930, 2400–3500, 1603, 1510,
max
1463, 1247, 1178, 1080, 1033, 980, 898, 822. Anal. Calcd.
SBA-Pr-SO H was used as a heterogeneous acid catalyst in
for C H N O (314.14): C 61.13, H 5.77, N 17.82, O
3
16 18
4
3
the mentioned reactions [10].
15.27; Found: C 61.16, H 5.72, N 17.88, O 15.24.
Fig. 1 Pyrazole-based natural products
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Journal of the Iranian Chemical Society
4
,4′‑((3‑Hydroxy,4‑Methoxyphenyl)methylene)
bis(3‑methyl‑1H‑pyrazol‑5‑ol) (5i)
1
Yellow powder (yield 90%); mp: 230–232 °C; H NMR
(
250 MHz, d -DMSO): 2.04 (s, 6H), 3.66 (s, 3H), 4.67 (s,
6
13
Scheme 1 Synthesis of pyrazolone 3
1
H), 6.15–6.72 (3H), 8.69 (s, 1H), 11.08 (br., 4H); C NMR
(
62.5 MHz, DMSO-d ): 10.80, 32.39, 56.17, 104.97, 112.29,
6
1
15.61, 117.47, 136.38, 140.20, 145.97, 146.32, 161.53;
condition was previously optimized, as shown in Table 1.
−
1
FT-IR (KBr) (ν /cm ): 3300, 2930, 1603, 1510, 1463,
Among the tested conditions, including refluxing in H O,
max
2
1
247, 1178, 1080, 1033, 980, 898, 822. Anal. Calcd. for
EtOH, a mixture of H O and EtOH and solvent-free system
2
C H N O (330.13): C 58.17, H 5.49, N 16.96, O 19.37;
along with the catalytic amount of SBA-Pr-SO H, the best
1
6
18
4
4
3
Found: C 58.14, H 5.52, N 16.98, O 19.36.
results regarding the high product yield and shorter reac-
tion time were obtained under solvent-free system (Table 1,
Molecular docking
entry 4). To make sure SBA-Pr-SO H catalyzed the reaction,
3
the progress of model reaction was studied in the absence
The crystal structure of phosphorylated RET tyrosine kinase
domain (2IVV) was taken from RCSB protein databank
of catalyst and no product was obtained (Table 1, entry 5).
Therefore, the role of SBA-Pr-SO H on the reaction pro-
3
(
http://www.pdb.org). This protein is complexed with the
gress is undeniable. Then after, generality of this reaction
inhibitor PP1 in the protein databank, so in the docking step,
this inhibitor was removed, and then, ligands in our data set
were docked in the active site of protein one by one. Dis-
covery Studio 2.5 (Accelrys Inc, San Diego, CA, USA) was
employed to dock the compounds to protein. All molecules
were sketched and typed with CHARMm force field then
partial charges were calculated by Momany–Rone option
catalyzed by SBA-Pr-SO H was considered by applying dif-
3
ferent derivatives of benzaldehyde (Scheme 2). The obtained
results in Table 2 show high yield of the products (85–97%)
within short reaction time (3–6 min).
The efficiency of SBA-Pr-SO H as a catalyst for the
3
preparation of bispyrazoles 5 has been compared with the
previously reported catalysts in the literature (Table 4). As
[
19]. Afterwards, they were minimized with Smart Mini-
it is clear, SBA-Pr-SO H is an efficient catalyst in terms
3
mizer which performs 1000 steps of steepest descent with a
RMS gradient tolerance of 3, followed by conjugate gradient
minimization. For preparation step of protein, CHARMm
force field was used, hydrogen atoms were added, all water
molecules were removed, and pH of protein was adjusted to
almost neutral, 7.4, using protein preparation protocol. The
protein active site was defined as a sphere with a radius of
of giving the products in high yields within short reaction
time. SEM image of SBA-Pr-SO H (Fig. 2) illustrates uni-
3
form rice-like particles with the size of 1 µm. The same
morphology was previously detected for SBA-15. It can be
established that the morphology of modified SBA-15 was
saved with no change during the modification procedure.
Moreover, eco-friendly characteristic of SBA-Pr-SO H is the
3
9
Å around the bounded ligand (PP1) to confirm atoms of
most important feature of in comparison, since it is recover-
the ligand and the side chains of the residues of the recep-
tor within 9 Å from the center of the binding site are free to
move. Then bounded ligand was removed from the binding
site. Other parameters were set by default protocol settings.
GOLD program was used to dock the compounds into recep-
tor [20].
able, safe, and non-toxic.
The recyclability of SBA-Pr-SO H was also determined
3
under optimized conditions for the synthesis of the model
compound 5a. For this aim, the mentioned model reaction
was repeated in the first run for three times to recover about
0.05 g of catalyst. Next, it was well washed and reactivated
with diluted acid and then reused under the same condi-
tions. The process of recycling was repeated for further three
times and the yields of 91, 90, and 88% were obtained. It
was found that the catalytic activity drops slightly from the
first use (95%) to the second use (91%) due to leaching of
some sulfonic acid groups which were weakly grafted on
Results and discussion
Synthesis of bispyrazole derivatives
In this study, the effect of SBA-Pr-SO H in the reaction
the outer surface of SBA-Pr-SO H. Furthermore, no signifi-
3
3
between pyrazolone and aldehyde was examined. Therefore,
initially, pyrazolone 3 was prepared, according to the pub-
lished research [21], through the reaction of ethyl acetoac-
etate 1 and hydrazine hydrate 2 in EtOH at room temperature
cant decrease in catalytic activity was observed for the other
cycles which there are no further leaching groups on the cat-
alyst surface. In fact, this catalyst is completely recoverable.
According to the proposed mechanism, as shown in
Scheme 3, the carbonyl group of aldehyde is first activated
(
Scheme 1). Then, the recrystallized pyrazolone 3 partici-
pated in the reaction with aldehydes 4a-i, while its reaction
by SBA-Pr-SO H to gain 4′. Then, the latter is attacked by
3
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Journal of the Iranian Chemical Society
Table 1 Optimization of the reaction conditions for the synthesis of 5a
Entry
Catalysts
Solvents
Conditions
Time (min)
Yields (%)
1
2
3
4
5
SBA-Pr-SO H
H O
EtOH
EtOH/ H O(1:1)
–
–
Reflux
Reflux
Reflux
120 °C
120 °C
120
50
90
4
120
20
80
72
95
3
2
SBA-Pr-SO H
3
SBA-Pr-SO H
3
2
SBA-Pr-SO H
3
–
Trace
Scheme 2 Synthesis of bispyra-
zole 5a-i
Table 2 Synthesis of pyrazol-chromeno[2,3-d]pyrimidinone deriva-
tives
Entry No.
R
Yield (%) m.p. (°C) m.p. Lit. (°C)
1
2
3
4
5
6
7
8
9
5a
5b
5c
5d
5e
5f
5g
5h
5i
4-Cl
H
4-Me
3-NO2
4-OMe
4-OH
4-F
95
93
87
92
85
85
97
95
218–220 220–222 [22]
239–241 242–244 [22]
200–202 191–193 [22]
271–273 271–272 [23]
180–182 189–191 [22]
255–257 262–264 [23]
200–202 New
3-OMe
3-OH-4-OMe 90
266–268 New
230–232 New
Fig. 2 SEM image of SBA-Pr-SO H
3
enolic form of pyrazolone 3′. Following by a dehydration
step, intermediate 7 is obtained which then reacts with 3′,
and after tautomerization, the final product 5 is produced.
subtilis (ATCC 465) and Staphylococcus aureus (ATCC
25923), Gram-negative bacteria including Pseudomonas
aeruginosa (ATCC 85327) and Escherichia coli (ATCC
25922) and for antifungal activity against Candida albicans
(ATCC 10231) via the disc-diffusion method. Their mini-
mum inhibitory concentration (MIC) was determined by
microdilution method and compared with the commercial
chloramphenicol, gentamicine, and nystatin. The low value
Anti‑bacterial and antifungal effect of compounds
5a‑i
All products 5a-i were investigated for anti-bacterial test
against some Gram-positive bacteria including Bacillus
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Journal of the Iranian Chemical Society
of MIC corresponds to the high anti-bacterial or antifun-
gal activity. As shown by the results in Table 4, all com-
pounds showed no significant anti-bacterial activities, while
compounds 5f and 5g showed good anti-C. albicans activity.
This fungus has been diagnosed with serious diseases such
as HIV and cancer. C. albicans is one of the most common
Table 3 Comparing different
Entry
Catalyst
Solvent
Conditions
Yield (%)
Time (min)
Year [Refs.]
conditions used for the synthesis
of bispyrazoles 5
a
1
2
3
4
5
6
7
8
[Dabco-H][AcO]
[MIm]ClO4
H O
80 °C
50 °C
90 °C
50 °C
Reflux
80 °C
70 °C
120 °C
98
1–5
2016 [24]
2016 [25]
2015 [26]
2015 [27]
2015 [22]
2015 [28]
2012 [29]
This work
2
b
–
–
77–94
79–97
84–95
91–98
85–94
75–95
85–97
20–60
25–45
10
10–60
1–13
10–15 h
3–6
[Et NH][HSO ]
3
4
CuCr O nanoparticles
H O
2
4
2
H PW O
EtOH
Glycerol
3
12 40
–
c
PTFA
SBA-Pr-SO H
H O
2
–
3
a
1
,4−Diazabicyclo[2.2.2]octane acetate
b
c
N-Methylimida-zolium perchlorate
Pyridine trifluoroacetate
Scheme 3 Proposed mechanism for the synthesis of bispyrazoles in the presence of SBA-Pr-SO H
3
Table 4 Minimum inhibitory
Compound
B. subtilis
S. aureus
E. coli
P. aeruginosa
C. albicans
concentration (µg/ml) of the
synthesized compounds against
bacteria and fungus obtained
from disc-diffusion method
5
5
5
5
5
5
5
5
5
a
b
c
d
e
f
g
h
i
>1024
>1024
>1024
>1024
>1024
>1024
>1024
>1024
>1024
4
>1024
>1024
>1024
512
>1024
>1024
>1024
>1024
>1024
8
>1024
>1024
>1024
>1024
>1024
>1024
>1024
>1024
>1024
4
>1024
>1024
>1024
>1024
>1024
>1024
>1024
>1024
>1024
256
512
>1024
>1024
>1024
>1024
32
128
>1024
>1024
–
Chloramphenicol
Gentamicin
Nystatin
0.125
–
0/5
–
0/5
–
1
–
–
8
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Journal of the Iranian Chemical Society
Table 5 Calculated gold value
Interaction
Compound
Gold Score
for the synthesized pyrazoles
5a
51.27
5b
48.19
5c
48.58
5d
52.93
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Journal of the Iranian Chemical Society
Table 5 (continued)
Compound
Gold Score
Interaction
5e
52.04
5f
48.85
5
g
51.38
51.60
53.43
5h
5
i
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Journal of the Iranian Chemical Society
Fig. 3 Best docked conformation of two synthesized compounds in the binding site of kinase domain (2IVV). a Molecule 5a and b molecule 5i
organisms that cause nosocomial infections. Therefore,
discovery and development of antifungal compounds are
essential.
Acknowledgements We gratefully acknowledge for the financial sup-
port from the Research Council of Alzahra University and the Univer-
sity of Tehran.
Docking results
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there is high reliability of GOLD method to reproduce the
known binding mode of these compounds. Table 5 shows
the Gold Score value and the binding mode of resulting
complexes.
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3
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