Synthesis, Structure, and Anti-Inflammatory Activity of Functionally Substituted Chalcones and Their Derivatives

Article abstract of DOI:10.1134/S1070363219070028

Functionally substituted chalcones, pyrazolines, and flavonones have been synthesized. Their structure has been studied by means of ¹H and ¹³C NMR spectroscopy, including COSY and HMQC experiments. Anti-inflammatory activity of the s

Full text of DOI:10.1134/S1070363219070028

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ISSN 1070-3632, Russian Journal of General Chemistry, 2019, Vol. 89, No. 7, pp. 1360–1367. © Pleiades Publishing, Ltd., 2019.
Russian Text © The Author(s), 2019, published in Zhurnal Obshchei Khimii, 2019, Vol. 89, No. 7, pp. 995–1003.
Synthesis, Structure, and Anti-Inflammatory Activity
of Functionally Substituted Chalcones and Their Derivatives
O. A. Nurkenova,b, M. K. Ibraeva*, I. A. Schepetkinc,d, A. I. Khlebnikovd,e, T. M. Seilkhanovf,
A. E. Arinovab, and M. B. Isabaevaa
a Karaganda State Technical University, bul. Mira 56, Karaganda, 100027 Kazakhstan
*e-mail: mkibr@mail.ru
b Institute of Organic Synthesis and Coal Chemistry of the Republic of Kazakhstan, Karaganda, Kazakhstan
c Department of Immunology and Infectious Diseases, Montana State University, Bozeman, Montana, United States
d N. Kizhner Center, National Research Tomsk Polytechnic University, Tomsk, Russia
e I.I. Polzunov Altai State Technical University, Barnaul, Russia
f Sh. Ualikhanov Kokshetau State University, Kokshetau, Kazakhstan
Received February 4, 2019; revised February 4, 2019; accepted February 10, 2019
Abstract—Functionally substituted chalcones, pyrazolines, and flavonones have been synthesized. Their structure
1
has been studied by means of H and 13C NMR spectroscopy, including COSY and HMQC experiments. Anti-
inflammatory activity of the synthesized chalcones, pyrazolines, and flavonones has been evaluated.
Keywords: substituted aromatic aldehydes, chalcone, pyrazoline, flavonone, cytokine, transcription factor NF-κB
DOI: 10.1134/S1070363219070028
Chalcones are of great interest because of easy synthe-
sis, high pharmacological activity, and possibility to be
used as synthons for obtaining many biologically active
heterocyclic compounds, in particular pyrazolines and fla-
vones [1]. The compounds with chalcone fragment exhibit
significant antitumor, antibacterial, antifungal, antiviral,
antimalarial, antihyperglycemic, anti-inflammatory, and
immunomodulating activity and possess chemoprotec-
tive and antioxidant properties [2–12]. Moreover, certain
chalcones can secure blood capillaries [6]. Thus, synthesis
of novel chalcones and nitrogen-containing heterocyclic
compounds based on them is an important issue.
strong absorption bands in the 1595–1582 cm–1 region,
corresponding to the vibrations of С=С bond conjugated
with the carbonyl group.
The 1Н NMR spectrum of compound 1 in deuterated
DMSO contained a strong signal at 3.76 ppm (intensity of
8
3Н) corresponding to protons of the methyl group ОСН3 .
The equivalent protons of the methoxyphenyl fragment
Н2,6 and Н3,5 resonated as doublets at 6.95 (2Н, 3J = 8.6 Hz)
and 7.77 ppm (2Н, 3J = 8.6 Hz), respectively. The pro-
tons at the double bond, Н9 and Н10, appeared as doublet
signals at 7.74 and 7.62 ppm (3J = 16.2 Hz), indicating
trans-configuration of the С=С bond. The equivalent СН
protons of another aromatic system appeared as doublet
Herein we studied the reactions of hydroxyacetophe-
nones with substituted aromatic aldehydes in the presence
of aqueous-alcoholic alkali solution (the Claisen–Schmidt
condensation). The reaction was carried out at equimolar
ratio of the components in the presence of 40% solution
of NaOH at room temperature for 62–85 h (Scheme 1).
The reaction progress was monitored using thin-layer
chromatography. The obtained chalcones 1–6 were col-
ored powders soluble in benzene and alcohols.
signals at 6.86 (Н15,17, 3J = 8.9 Hz) and 8.03 ppm (Н14,18
,
3J = 8.9 Hz). The broadened singlet signal at 10.39 ppm
indicated the presence of the phenolic OH-group.
12
O
14
17
9
5
2
4
13
6
15
16
11
10
1
3
18
The structures of the prepared chalcones 1–6 were
HO
OCH3
1
19
confirmed using IR as well as Н and 13С NMR spec-
7
8
1
troscopy. The IR spectra of compounds 1–6 contained
1360

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SYNTHESIS, STRUCTURE, AND ANTI-INFLAMMATORY ACTIVITY
Scheme 1.
1361
R6
O
O
H
O
R6
R5
R5
NaOH
CH3
+
R1
R2 R3
R4
R3
R1
R2
R4
1ꢀ6
R1 = OH, R2 = R3 = R4 = R6 = H, R5 = OMe (1); R1 = R4 = R5 = R6 = H, R2 = R3 = OH (2); R1 = R2 = OH, R3 = R4 = R6 = H,
R5 = OMe (3); R1 = R3 = R4 = R6 = H, R2 = R5 = OH (4); R1 = R3 = R6 = H, R2 = R5 = OH, R4 = OEt (5); R1 = R6 = Br, R2 =
R4 = R5 = H, R3 = OH (6).
The 13С NMR spectrum of compound 1 contained
the signal of methoxy group at 55.83 ppm. The signals
at 114.87 (С2,6), 115.88 (С15,17), 131.05 (С3,5), and
131.57 ppm (С14,18) corresponded to the carbon atoms
of aromatic systems. Quaternary carbon atoms appeared
at 161.62 (С1), 128.04 (С4), 129.84 (С13), and 162.61
(С16) ppm. The signals at 120.08 and 143.21 ppm could
be assigned to the С9 and С10 carbon atoms involved in
the multiple bond formation. The signal in the weakest
field (187.57 ppm) corresponded to the С11 atom of the
carbonyl group.
We investigated the reactions of the prepared chal-
cones 1–6 with hydrazine hydrate to further functionalize
the obtained compounds. It was observed that refluxing
the chalcones with hydrazine hydrate in ethanol resulted
in intramolecular cyclocondensation of intermediate hy-
drazine with the formation of the corresponding pyrazole
derivatives 7–11 (Scheme 2).
Structures of compounds 7–11 were confirmed using IR
and NMR spectroscopy. For example, IR spectra of pyrazo-
lines 7–11 revealed distinct absorption band correspond-
ing to the C=N bond of pyrazole cycle at 1601–1605 cm–1.
1Н NMR spectrum of 4-[5-(4-methoxyphenyl)-4,5-
dihydro-1Н-pyrazol-3-yl]phenol 7 contained four groups
of signals in weak field corresponded to protons of 4-hy-
droxy and 4-methoxyphenyl fragments. Two doublets at
7.40 and 7.23 ppm corresponded to ortho and meta-pro-
tons of 4-hydroxyphenyl fragment, two doublets at 6.84
and 6.72 ppm corresponded to ortho and meta-protons
4-methoxyphenyl fragment. Astrong singlet at 3.67 ppm
could be assigned to protons of methoxy group. Another
group of signals (triplet at 4.63–4.68 ppm) corresponded
to methine proton of pyrazoline fragment. Methylene
protons of that fragment resonated at 2.65–2.72 ppm as
two doublets. A weak signal at 9.67 ppm corresponded
to the NH-proton of the pyrazoline fragment.
The structure of compound 1 was also confirmed by
two-dimensional COSY1H–1H and HMQC 1H–13C NMR
methods revealing the homo- and heteronuclear spin-spin
1
correlations. The H–1H COSY spectra of compound 1
contained the spin-spin correlations of aromatic protons
and olefinic protons Н9 and Н10 via three bonds (Fig. 1a).
Simple interactions between the protons and carbon atoms
were found using 1H–13C HMQC spectroscopy (Fig. 1b).
Cyclocondensation reaction of hydrazines with α,β-
unsaturated ketones is an important synthetic route to
obtain 1,2-azoles. Several pyrazole derivatives exhibit
properties of analgesics and thrombocyte aggregation
inhibitors [13], possess strong antibacterial [14] and
anesthetic [15] action.
(b)
(a)
Fig. 1. Main correlations in COSY (a) and HMQC (b) spectra of compound 1.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 89 No. 7 2019

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1362
NURKENOV et al.
Scheme 2.
O
N2 1NH
R6
R5
11
10
17
R6
R5
3
5
6
12
16
15
14
4
N2H4·H2O
EtOH
7
9
13
8
R1
R2 R3
R1
R2 R3
R4
R4
1ꢀ6
7ꢀ11
R1 = OH, R2 = R3 = R4 = R6 = H, R5 = OMe (7); R1 = R4 = R5 = R6 = H, R2 = R3 = OH (8); R1 = R2 = OH, R3 = R4 = R6 = H,
R5 = OMe (9); R1 = R3 = R4 = R6 = H, R2 = R5 = OH (10); R1 = R3 = R6 = H, R2 = R5 = OH, R4 = OEt (11).
Certain processes of chalcones and flavonones bio-
genesis in plants are similar. Therefore, combination
of structural features of these compounds in a single
molecule is a promising approach to obtain highly ef-
ficient bioactive compounds [16, 17]. So, we prepared
flavonones 12–15 from the obtained 2-hydroxychalcones
in ethanol medium in the presence of catalytic amount
of triethylamine. Prolonged refluxing in 95% ethanol led
to the formation of flavonones 12–15 (Scheme 3). It was
shown that transformation of chalcones into flavonones
was catalyzed by water molecules.
peared at 5.47 (Н2), 2.69–3.31 (Н3), 7.06 (Н7), 7.55 (Н8),
7.76 (Н9), and 7.04 ppm (Н10). The protons of СН groups
of the phenyl fragments resonated at 6.77–6.90 ppm. A
signal in the weakest field at 9.00 ppm corresponded to
the Н21 atom of the hydroxyl group.
The assignment of the 13С NMR signals was carried
1
out using the DEPT method. The assignment of the Н
NMR signals was made using two-dimensional COSY
and TOCSY NMR spectroscopy (Fig. 2).
Anti-inflammatory and cytotoxic activity of the pre-
pared chalcones 1, 3–5, pyrazolines 8, 9, and flavones
12, 14, and 15 was estimated on the cultures of human
monocytic cell lines MonoMac-6 and THP-1Blue. The
results are given in the table.
The structures of flavonones 12–15 were confirmed
using IR as well as 1Н and 13С NMR spectroscopy. The
1Н NMR spectrum of compound 15 contained a triplet at
1.29 ppm and a multiplet at 3.98–4.03 ppm corresponding
to protons of ethoxy group at the С20 and С19 atoms. The
protons of methylene and CH groups of the fused rings ap-
It was figured out that chalcone 5 and flavone 15 were
cytotoxic against monocytic MonoMac-6 cells, so it was
Scheme 3.
O H
H
O
R4
OH
O
EtOH
R3
R2
R1
OH
R2
R4
R1
R3
2ꢀ5
R4
R3
R4
R3
Oꢀ
O
O
O
ꢀH2O
R2
R2
R1
H
R1
H
12ꢀ15
R1 = R3 = R4 = H, R2 = OH (12); R1 = OH, R2 = R3 = H, R4 = OMe (13); R1 = R2 = R3 = H, R4 = OH (14); R1 = R2 = H, R3 =
OEt, R4 = OH (15).
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SYNTHESIS, STRUCTURE, AND ANTI-INFLAMMATORY ACTIVITY
1363
impossible to correctly estimate their anti-inflammatory
potential for that culture. Pyrazoline 9 and flavone 14
inhibited the production of anti-inflammatory cytokines
interleukin-6 (IL6) and tumor necrosis factor (TNF).
However, those compounds possibly should not be con-
sidered as promising ones because of their low activity
(IC50 > 30 μM).
21
OH
15
16
Fig. 2. Main correlations in COSY1Н–1Н and TOCSY1Н–1Н
spectra of compound 15.
14
13
1
O
7
2
6
5
8
9
11
OꢀCH2ꢀCH3
12
18 19
20
3
4
inhibition of the NF-κB activity which was estimated
using the level of alkaline phosphatase production in
THP-1Blue cells was very low (compound 3 and 4) or
zero (compounds 1, 8, and 12). Those compounds and
their analogs could recommended for further investigation
of anti-inflammatory activity, because they did not exhibit
(1, 12) or practically did not exhibit (3, 4, 8) cytotoxic
activity at the concentration range with found IC50 values
in the inhibition of cytokine production test.
10
O
17
15
Chalcones 1, 3, and 4, pyrazoline 8, and flavone 12
inhibited the production of tumor necrosis factor and/
or interleukin-6. The mechanism of inhibition of tumor
necrosis factor and interleukin-6 production by those
compounds obviously was independent of the transcrip-
tional activity of NF-κB. The reason was the fact that
Anti-inflammatory activity (in vitro), cytotoxicity, physical and chemical properties of the investigated chalcones, pyrazolines,
and flavonones
IC50, μM
Eh,
kcal/mol
Comp. no.
S, Å2
lgP
MonoMac-6 cells
IL6a
THP-1Blue cells
alkali phosphatase
TNFa
toxicity
toxicity
Chalcones
b
b
1
3
4
5
9.9 (А)
15.6 (А)
10.9 (A)
17.4 (–)
24.2 (A)
18.5 (A)
19.7 (A)
–b (–)
–
–
82.1
36.5
71.2
27.8
430.9
430.5
368.4
442.5
3.14
2.85
3.11
3.20
–11.97
–17.49
–16.12
–15.62
75.0
69.5
32.1
51.2
53.0
48.4
Pyrazolines
b
b
–b (N)
9.6 (A)
>60
–
–
311.8
406.1
2.90
2.64
–12.95
–18.76
8
9
b
b
b
52.0 (N)
33.8 (N)
–
–
–
Flavonones
b
b
b
12
14
15
35.0 (N)
51.0 (N)
24.5 (–)
15.5 (A)
50.0 (N)
9.0 (–)
–
–
–
308.9
334.7
412.1
2.56
2.56
2.65
–8.78
–10.86
–10.43
b
b
b
–
–
–
35.5
>50
34.1
a
No inhibition of production or cytotoxicity at concentrations <100 μM.
b The compounds considered active (A, IC50<30 μM) or conditionally inactive (N, IC50>30 μM) during classification analysis are marked
in parentheses.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 89 No. 7 2019