Synthesis and Biological Evaluation of Novel Bischalcone Derivatives as Carbonic Anhydrase Inhibitors

Article abstract of DOI:10.1002/ardp.201600122

Design and synthesis of a new type of bischalcones as an alternative to natural and synthetic bischalcones are reported for the first time. Key steps involved the solvent-free Claisen–Schmidt condensation of chalcones, and the successful first application

Full text of DOI:10.1002/ardp.201600122

RCHH HARM
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Arch. Pharm. Chem. Life Sci. 2016, 349, 1–8
Archiv der Pharmazie
Full Paper
Synthesis and Biological Evaluation of Novel Bischalcone
Derivatives as Carbonic Anhydrase Inhibitors
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Tayfun Arslan , Gonca CS elik , Habip CS elik , Murat SS enturk , Nurettin Yaylı , and Deniz Ekinci
1
Technical Sciences Vocational School, Giresun University, Giresun, Turkey
Department of Chemistry, Karadeniz Technical University, Trabzon, Turkey
Department of Chemistry, Agri Ibrahim Cecen University, Agri, Turkey
Department of Pharmacy, Karadeniz Technical University, Trabzon, Turkey
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3
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Department of Agricultural Biotechnology, Ondokuz Mayis University, Samsun, Turkey
Design and synthesis of a new type of bischalcones as an alternative to natural and synthetic bischalcones
are reported for the first time. Key steps involved the solvent-free Claisen–Schmidt condensation of
chalcones, and the successful first application of the diazotization–diazocoupling reaction in the synthesis
–
of C–N N–C-linked bischalcones by simple structural modification of p-aminoacetophenone. The
–
structures of all compounds were confirmed by means of FT-IR, 1H and 13C NMR, ESI/MS, and elemental
analysis. In addition, the newly synthesized compounds were screened for carbonic anhydrase inhibition
activities. Almost all bischalcones exhibited moderate-to-good inhibitory activities.
Keywords: Bischalcone / Carbonic anhydrase inhibition / Diazotization / Solvent-free
Received: April 25, 2016; Revised: June 10, 2016; Accepted: June 22, 2016
DOI 10.1002/ardp.201600122
Additional supporting information may be found in the online version of this article at the publisher’s web-site.
:
antiplasmodial and moderate antiproliferative, antiprotozoal
activities. In addition, rhuschalcone (I) displays important
Introduction
Chalcone and its analogs are of considerable interest for both
syntheticorganicandmedicinalchemistsduetotheirremarkable
range of biological and pharmaceutical properties. Chalcone
derivatives have been used to treat certain kinds of cancer [1],
diabetes [2], and to prevent cardiovascular diseases [3]. Some of
its derivatives show antimicrobial [4], antibacterial [5], antifun-
gal[6], andanti-HIVactivity[7].Bischalconesarewellrepresented
intheAnacardiaceafamily.TheRhusgenusisalsoarichsourcefor
biflavonoids and bischalcones. In general, naturally occurring
bischalcones, rhuschalcone (I), littorachalcone (II), and verbena-
chalcone (III) as depicted in Figure 1 carry either a C–O–C or C–C
linkage between the two chalcone fragments [8–11]. Rhuschal-
cone II–VI has been isolated from the root bark of Rhus pyroides
and synthetic analogs have been shown to possess strong
cytotoxic activity against the HT29 and HCT-116 colon tumor
cell lines [9, 11, 12]. Its dihydro analogs, bearing diaryl ether
linkage, both littorachalcone (II) and verbenachalcone (III),
showed a significant extension of nerve growth factor-mediated
neurite outgrowth from the PC12D cells [10, 11]. They were
synthesized by phenolic oxidation of the dihalogenated phenols.
Recently, a number of pharmacologically interesting bischalcone
analogs were synthesized with structural modifications to
improve their anti-cancer potential and chemoprotective
properties [13]. Examples of these transformations are formed
by joining two chalcone moieties together with different
linkages such as bi-aryl, di-aryl ether, methylene, the carbon
chains of varying lengths, Mannich base, etc. using Suzuki–
Miyaura [9], Mannich [8], Ullmann [11], and Williamson [14]
reactions. Synthetic bischalcone bearing piperazine Mannich
base linkage, which is (E)-1-(4-(4-(5-cinnamoyl-2-hydroxybenzyl)-
piperazin-1-yl)phenyl)-3-phenylprop-2-en-1-one (IV), showed
inhibition of nitric oxide (NO) production in microglial cells
and for in vitro anticancer activity. 1,2-Di(20-benzoyl-4-styryloxy)-
ethane and its derivatives (V) with a structure of two chalcone
moieties connected by the carbon chains of varying lengths have
Correspondence: Dr. Tayfun Arslan, Technical Sciences Vocational
School, Giresun University, 28049 Giresun, Turkey.
E-mail: tayfun.arslan@giresun.edu.tr
Fax: 00904542165457
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Arch. Pharm. Chem. Life Sci. 2016, 349, 1–8
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Figure 1. Natural and synthetic bischalcones.
been synthesized through the Williamson reaction and they
have been shown to possess antimicrobial activity [14] (Fig. 1).
In addition, aromatic and heteroaromatic azo compounds
constitute the most important class of synthetic dyes, which
are used commonly in applications such as organic dyes
[15, 16], indicators [17], and therapies [18]. They are also
utilized in the area of nonlinear optics [19] and optical storage
media [20]. Moreover, azo compounds are also involved in
a number of biological reactions such as inhibition of DNA,
RNA and protein synthesis, carcinogenesis, and nitrogen
fixation [21–23]. For this reason, the synthesis of aromatic azo
compounds has attracted great attention.
Carbonic anhydrase (carbonate hydrolase, EC 4.2.1.1; CA)
is a zinc(II)-dependent enzyme that catalyzes the reversible
hydration of carbon dioxide to hydrogencarbonate and a
proton [24]. CA isozymes have been the targets of drug
developments for the treatments of glaucoma, epilepsy,
high-altitude sickness, as well as cancer [24, 25]. CA isozymes
are involved in the pH homeostasis, ion transport, water
and electrolyte balance, bone resorption, calcification, and
tumorigenesis [24]. In a recent preliminary work from our
group, we investigated the interaction between natural
phenolic compounds, amino acid sulfonamide derivatives,
hydroxy/methoxy organic compounds, and some nitroaro-
matic compounds with two cytosolic catalytically active
isoforms (CA I and II) of the metalloenzyme CA [26–33].
Over the last few years, bischalcone and its derivatives
have gained much interest because of their wide range of
applicationsinsyntheticandpharmaceuticalchemistry.Current
research focuses on the transformations of chalcones into
bischalcones in particular. Thus, we utilized the diazotization
and diazocoupling reaction for the synthesis of bischalcones.
Moreover, from a synthetic aspect, this effort provided an
excellent opportunity to achieve the new types of diazotization
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Arch. Pharm. Chem. Life Sci. 2016, 349, 1–8
Bischalcone Derivatives as Carbonic Anhydrase Inhibitors
Archiv der Pharmazie
and diazocoupling reaction in the synthesis of novel type
the inhibitory effects of these compounds on two a-CA
isozymes, hCA I and hCA II.
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bischalcones, which have C–N N–C linked with various
–
substitutions in the B-ring and D-ring of the chalcone moiety.
It is known that CA has been purified many times from
different organisms and the effects of various chemicals,
pesticides, and drugs have been investigated on its
activity [26–33]. In this study, CA I and II were purified from
human erythrocytes [27], and the activity of the effluents was
determined by the hydratase method, with CO2 as substrate
and further kinetic studies were performed using the esterase
activity method, with 4-nitrophenyl acetate (NPA) as sub-
strate [21]. Here, we report the inhibitory effects of
bischalcone derivatives on the CA esterase activity of isoforms
hCA I and II. Data of Table 1 show the following regarding
inhibition of hCA I and II with compounds 3–14:
Results and discussion
Chemistry
The convergence of the strategy enables the synthesis of a new
–
type of bischalcones bearing a C–N N–C linkage with simple
–
structural modification of p-aminoacetophenone. In the
synthetic route, the first step involves its diazotization and
azo coupling. Bisketone (3) has been converted into the
correspondingdiazoniumsaltbyusingatreatmentwithsodium
nitrite and HCI at 0–5°C to give the corresponding benzene-
diazonium chlorides, which were used directly in the next step
without any further purification [34]. Subsequently, the
diazonium salt was coupled with 3-hydroxyacetophenone in
a diluteNaOH solutionat0–5°C for4 h leadingto theformation
of bisketone (3). The crude product was purified by recrystalli-
zation. In the previous studies, bisketone (3) was first found in
low yield as a rearrangement product of 4,40-diacetylazoxy-
benzene with sulfuric acid [35]. However, there are no earlier
reports regarding its synthesis. Step two, the transformation of
bisketone into bischalcone includes the Claisen–Schmidt reac-
tion of two equivalents of the corresponding benzaldehydes
with bisketone using the grindstone technique. This technique
is superior to the conventional method as it is eco-friendly, high
yielding, non-hazardous, simple, and convenient [9, 36, 37].
Therefore, the grindstone technique was used for the synthesis
of the new type bischalcones. Claisen–Schmidt condensation,
which is the most important reaction in the formation of 1,3-
diphenyl-2-propene-1-ones (chalcones), aldehydes-bearing
methoxy, methyl, and halogens group, reacted with bisketone
(3) in the presence of the solid KOH in combination with
grinding under solvent-free conditions at room temperature.
Thus, the synthesis of the unsymmetrical bischalcone, including
(1) Against the slow cytosolic isozyme hCA I, compounds 5, 7,
and 11 behaved as weak inhibitors. A second group of
derivatives, including 3, 6, 9, 10, 13, and acetazolamide
(AZA), showed better inhibitory activity compared to
the previously mentioned compounds, with KIs in the
range of 165.35–274.19 nM. Molecules 4, 8, 12, and 14
were among the best inhibitors in this series of
nitrobenzene compounds. Data of Table 1 also show
that similarly to AZA, some of the investigated bischal-
cone compounds act as competitive inhibitors with 4-NPA
as substrate, that is, they bind to the same regions of the
active site cavity as the substrate. However, the binding
site of 4-NPA itself is unknown, but it is presumed to be
in the same region as that of CO2, the physiological
substrate of this enzyme [38]. Similarly to methoxy-
phenolic compounds investigated earlier by us [39–41],
these compounds act as competitive inhibitors with 4-
NPA as substrate, that is, they bind to same regions of the
active site cavity as compared to the substrate (Table 1).
(2) A rather similar activity of these compounds has been
observed also for the inhibition of the rapid cytosolic
isozyme, hCA II (Table 1). Thus, a first group of derivatives,
3, 5, 7, 9, and 14, showed modest hCA II inhibitory activity
with KIs in the range of 307.52–645.39 nM (Table 1),
whereas the remaining seven derivatives, the same
compounds acting as efficient hCA II inhibitors, showed
KIs in the range of 154.45–268.87 nM. Structure–activity
relationship was thus quite similar in these small groups
of methoxy derivatives, for both the inhibition of hCA I
and II, although differences of affinity between the two
isozymes are evident. Again most of these compounds
acted as competitive inhibitors with 4-NPA as substrate
(Table 1).
–
the C–N N–C bond, was achieved in step two (Scheme 1). The
–
structuresofallthecompoundswereconfirmedbyFT-IR,1Hand
13C NMR, ESI/MS, and elemental analysis.
The synthetic route to the bischalcones is outlined in Table 1.
The crude product was contaminated with some starting
materials, which could easily be removed by recrystallization
two times with EtOH/H2O to obtain red crystals. The ESI/MS
spectra of the compounds showed [MþH]þ peaks corre-
sponding to their molecular formula. The NMR spectra
(1H and 13C NMR) are consistent with the proposed structures.
The trans-(E) geometry of the bischalcones 4–14 double bond
was evident by the large olefinic coupling constant between
the relevant signals in the 1H NMR spectrum (J ¼ 15.0–16.4 Hz).
Conclusion
Biological evaluation of the synthesized and
reference compounds for CA inhibitory activity
In the current study, we report the synthesis of bischalcone
derivatives containing a methoxygroup(3–14). We determined
In conclusion, an environmentally benign approach, and
synthesis of new type bischalcones were successfully
accomplished via diazotization and diazocoupling by using
the grinding method. This synthesis constitutes the first
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Scheme 1. Synthesis of new type bischalcone derivatives using the diazotization–diazocoupling reaction.
application of the diazotization–diazocoupling reaction in
performed on a Costech ESC 4010 instrument. The IR spectra
were determined using a Perkin Elmer 1600 Fourier Trans-
–
the synthesis of C–N N–C-linked bischalcones. The newly
–
synthesized compounds were also evaluated for CA inhibition
activity. Bischalcones are the most valuable synthons for
synthetic organic chemists, and by means of proper planning
and design of these active compounds can give inspiration
for the synthesis of many important and exotic heterocyclic
compounds as pharmaceuticals.
form-infrared (FT-IR) spectrophotometer on a KBr disc.
Melting points were determined by using a Barnstead
electrothermal 9200 series digital apparatus. Ultraviolet–
visible (UV–Vis) absorption spectra were recorded on a
Unicam UV2-100 spectrophotometer. CA inhibitory activity
was determined according to Verpoorte et al. [38].
The InChI codes of the investigated compounds are
provided as Supporting Information.
Experimental
Synthesis of bisketone (3)
Chemistry
4-Aminoacetophenone (2 g, 14.8 mmol) was dissolved in 5 mL
of concentrated HCl. The solution was cooled down in a ice-
salt bath and then cold solution of NaNO2 (1 g, 14.8 mmol) in
10 mL of water was slowly added. The reaction mixture
resulted was stirred for 3 h at 0–5°C. The resulting diazonium
salt was cooled in ice-salt bath. 3-Hydroxyacetophenone (2 g,
14.8 mmol) was dissolved in a dilute NaOH solution and
1H and 13C spectra were recorded on a Varian Mercury 200
(50)-MHz and Bruker Ascend 400 (100)-MHz spectrometers
and chemical shifts were reported (l) relative to Me4Si
as internal standard. High-resolution mass spectrometric
analysis was carried out on an Agilent 1260 Infinity Series
Q-TOF LC/MS (ESI/MS). The elemental analyses were
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Arch. Pharm. Chem. Life Sci. 2016, 349, 1–8
Bischalcone Derivatives as Carbonic Anhydrase Inhibitors
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Table 1. Characterization and KI values of the tested compounds.
hCA I KI
hCA II KI
Product
R
Yield (%)
M.p. (°C)
UVa) lnm (log e)
(nM)b)
(nM)b)
3
4
5
6
7
8
9
10
11
12
13
14
AZA
–
62
60
77
88
84
83
79
61
86
80
72
65
–
208–210
106–108
92–94
87–89
142–144
80–82
102–104
88–90
97–99
136–138
90–92
537 (3.4)
563 (3.4)
358 (4.6)
290 (4.3)
354 (4.6)
312 (4.5)
379 (4.6)
379 (4.6)
371 (4.6)
326 (4.4)
378 (4.6)
375 (4.6)
–
–
–
274.19
112.34
325.12
165.35
308.88
111.22
177.91
188.56
323.30
72.90
645.39
154.45
418.06
227.56
307.52
193.19
446.62
208.53
182.31
166.54
268.87
319.13
12.00
H
–
–
2-OMe
3-OMe
4-OMe
2,3-OMe
2,4-OMe
2,5-OMe
3,4-OMe
3,5-OMe
2,3,4-OMe
3,4,5-OMe
–
566 (3.4)
375 (4.4)
605 (3.5)
378 (4.6)
554 (3.5)
570 (3.2)
567 (3.6)
379 (4.4)
377 (4.6)
554 (3.5)
–
–
571 (3.5)
–
608 (3.7)
–
–
–
–
566 (3.4)
179.11
103.55
250.00
145–147
–
–
–
a) The UV–Vis absorption spectra were recorded using DMF in concentration 1.10ꢀ8 M.
b) Mean from at least three determinations. Errors in the range of ꢁ3% of the reported value (data not shown).
cooled in ice-salt bath and then the cold diazonium solution
was added to this cooled solution dropwise at 0–5°C. After
stirring the reaction mixture for 4 h, pH of the reaction
mixture was adjusted at 4–5 by the simultaneous addition
of a saturated sodium acetate solution. Subsequently, it
was stirred for 2 h. The precipitate was filtered, dried, and
recrystallized from EtOH/H2O (1:1).
7.50 (B part of AB system, J ¼ 16.0, 1H), 7.46 (m, 5H, ArH), 7.29
(A part of AB system, J ¼ 16.0, 1H), 7.07 (s, 1H, ArH). 13C NMR
(50 MHz, DMSO-d6): d 195.24, 189.35, 161.16, 154.36, 144.81,
143.28, 142.98, 141.09, 138.77, 134.34, 134.32, 130.43, 130.21,
129.19, 128.69, 128.64, 128.21, 127.99, 127.86, 122.53, 121.53,
120.22, 118.12, 114.81. ESI/MS (m/z): [MþH]þ 459.17. Anal.
calcd. for C34H30N2O7: C, 78.59; H, 4.84; N, 6.11. Found: C,
78.62; H, 4.80; N, 6.10.
General methods for the synthesis of bischalcones 4–14
Bisketone (3) (2 mmol), substituted benzaldehyde (4 mmol),
and potassium hydroxyde (4 mmol) are ground in a mortar
with a pestle at room temperature for 10–15 min to obtain a
homogeneous mixture. The progress of reaction was moni-
tored by TLC. After completion of the reaction, the mixture
was poured into ice water (10 mL), adjusted to pH 2–3
with 1 M HCl. The dark red solid thus obtained was filtered,
washed with several times water, dried, and crystallized from
EtOH/H2O (1:1).
(E)-1-(3-Hydroxy-4-((E)-(4-((E)-3-(2-methoxyphenyl)-
acryloyl)phenyl)diazenyl)phenyl)-3-(2-methoxyphenyl)-
prop-2-en-1-one (5)
Dark red solid, FT-IR (KBr, cmꢀ1):3396, 3044, 1673, 1533. 1H NMR
(200 MHz, CDCl3): d 8.16 (d, J ¼ 8.6, 1H, ArH), 8.02 (m, 2H, ArH),
7.97 (m, 1H, ArH), 7.82–7.89 (m, 3H, ArH), 7.80 (d, J ¼ 7.8, 1H,
ArH), 7.61 (B part of AB system, J ¼ 15.0, 1H), 7.41–7.44 (m, 2H,
ArH), 7.25 (A part of AB system, J ¼ 15.0, 1H), 7.10–7.12 (m, 2H,
ArH), 7.01–7.05 (m, 2H, ArH), 6.96 (s, 1H, ArH), 3.86 (s, OCH3, 3H),
3.74 (s, OCH3, 3H). 13C NMR (50 MHz, CDCl3): d 195.19, 187.94,
161.98, 158.75, 158.48, 154.57, 142.93, 141.99, 139.36, 139.22,
138.53, 133.07, 132.85, 129.01, 128.59, 123.67, 123.15, 122.88,
122.01, 121.19, 119.97, 112.23, 112.21, 61.15, 51.05. ESI/MS
(m/z): [MþH]þ 519.18. Anal. calcd. for C32H26N2O5: C, 74.12;
H, 5.05; N, 5.40. Found: C, 74.10; H, 5.08; N, 5.38.
(E)-1-(4-((4-Acetyl-2-hydroxyphenyl)diazenyl)phenyl)-
ethanone (3)
Dark red solid, FT-IR (KBr, cmꢀ1): 3356, 1681, 1678, 1268.
1H NMR (200 MHz, CDCl3): d 8.10 (d, J ¼ 8.2, 2H), 7.83 (d, J ¼ 8.2,
2H), 7.76 (d, J ¼ 9.0, 1H), 7.00 (d, J ¼ 9.0, 1H), 6.90 (s, 1H), 2.60
(s, 3H), 2.51 (s, 3H). 13C NMR (50 MHz, CDCl3): d 202.85, 198.07,
162.06, 154.83, 142.67, 142.39, 138.58, 130.34, 123.14, 121.91,
118.71, 114.42, 32.92, 27.64. ESI/MS (m/z): [MþH]þ 283.08.
Anal. calcd. for C16H14N2O3: C, 68.07; H, 5.00; N, 9.92. Found: C,
68.10; H, 5.01; N, 9.96.
(E)-1-(3-Hydroxy-4-((E)-(4-((E)-3-(3-methoxyphenyl)-
acryloyl)phenyl)diazenyl)phenyl)-3-(3-methoxyphenyl)-
prop-2-en-1-one (6)
Darkredsolid,FT-IR(KBr,cmꢀ1):3258,3045,1657,1593.1HNMR
(200 MHz, CDCl3): d 8.03 (m, 2H, ArH), 7.98 (m, 2H, ArH), 7.87
(d, J ¼ 8.6, 1H, ArH), 7.82 (d, J ¼ 8.6, 1H, ArH), 7.42 (A part of
AB system, J ¼ 16.4, 1H), 7.80 (B part of AB system, J ¼ 16.4, 1H),
7.30 (m, 2H, ArH), 7.22 (m, 2H, ArH), 7.13 (s, 2H, ArH), 6.99–7.10
(m, 2H, ArH), 6.90 (s, 1H, ArH), 3.86 (s, OCH3, 3H), 3.74 (s, OCH3,
3H). 13C NMR (50 MHz, CDCl3): d 196.11, 189.99, 160.34, 159.82,
(E)-1-(4-((E)-(4-Cinnamoyl-2-hydroxyphenyl)diazenyl)-
phenyl)-3-phenylprop-2-en-1-one (4)
Dark red solid, FT-IR (KBr, cmꢀ1): 3400, 3056, 1676, 1533.
1H NMR (200 MHz, DMSO-d6): d 8.21 (d, J ¼ 8.6, 1H, ArH), 7.92
(d, J ¼ 8.6, 1H, ArH), 7.85–7.87 (m, 7H, ArH), 7.69 (m, 2H, ArH),
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159.76, 154.74, 145.40, 144.25, 143.71, 140.53, 139.04, 135.91,
135.19, 129.90, 129.53, 127.99, 129.90, 122.86, 121.92, 121.18,
121.07, 116.54, 115.21, 113.45, 55.32, 55.20. ESI/MS (m/z):
[MþH]þ 519.18. Anal. calcd. for C32H26N2O5: C, 74.12; H, 5.05;
N, 5.40. Found: C, 74.10; H, 5.07; N, 5.38.
(E)-3-(2,5-Dimethoxyphenyl)-1-(4-((E)-(4-((E)-3-(2,5-
dimethoxyphenyl)acryloyl)-2-hydroxyphenyl)diazenyl)-
phenyl)prop-2-en-1-one (10)
Dark red solid, FT-IR (KBr, cmꢀ1): 3395, 3044, 1672, 1532.
1H NMR (200 MHz, CDCl3): d 8.21 (d, J ¼ 8.6, 1H, ArH), 7.96 (d,
J ¼ 8.6, 2H, ArH), 7.91 (d, J ¼ 8.6, 1H, ArH), 7.81 (d, J ¼ 8.6, 2H,
ArH), 7.64 (B part of AB system, J ¼ 16.4, 1H), 7.31 (A part of AB
system, J ¼ 16.4, 1H), 7.24 (bs, 2H, ArH), 7.04–7.06 (bs, 3H,
ArH), 6.96 (bs, 2H, ArH), 3.81 (s, OCH3, 3H), 3.77 (s, OCH3, 3H),
3.69 (s, OCH3, 3H), 3.63 (s, OCH3, 3H). 13C NMR (50 MHz, CDCl3):
d 195.92, 189.09, 162.21, 154.88, 153.89, 153.81, 153.49,
153.16, 143.20, 142.35, 139.46, 139.30, 138.32, 129.04, 123.94,
123.13, 122.45, 121.26, 119.17, 119.04, 113.71, 113.21, 113.02,
56.82, 56.73, 56.37, 56.14. ESI/MS (m/z): [MþH]þ 579.21. Anal.
calcd. for C32H26N2O5: C, 70.58; H, 5.23; N, 4.84. Found: C,
70.60; H, 5.25; N, 4.82.
(E)-1-(3-Hydroxy-4-((E)-(4-((E)-3-(4-methoxyphenyl)-
acryloyl)phenyl)diazenyl)phenyl)-3-(4-methoxyphenyl)-
prop-2-en-1-one (7)
Darkredsolid,FT-IR(KBr,cmꢀ1):3201,3049,1655,1571.1HNMR
(200 MHz, DMSO-d6): d 8.20 (d, J ¼ 7.4, 2H, ArH), 8.16 (d, J ¼ 7.4,
2H, ArH), 7.81 (m, 1H, ArH), 7.78 (m, 1H, ArH), 7.76 (B part of
AB system, J ¼ 15.2, 1H), 7.63 (d, J ¼ 7.8, 2H, ArH), 7.31 (A part
of AB system, J ¼ 15.2, 1H), 7.63 (d, J ¼ 7.8, 2H, ArH), 7.18 (s, 1H,
ArH), 6.98 (d, J ¼ 7.8, 2H, ArH), 3.80 (s, OCH3, 3H), 3.75 (s, OCH3,
3H). 13C NMR (50MHz, DMSO-d6): d 195.21, 188.91, 162.20,
162.07, 154.83, 145.16, 144.40, 143.16, 142.66, 139.63, 131.66,
131.20, 130.43, 131.20, 130.18, 127.92, 127.54, 126.42, 123.01,
121.02, 120.10, 118.65, 115.12, 56.08. ESI/MS (m/z): [MþH]þ
519.17. Anal. calcd. for C32H26N2O5: C, 74.12; H, 5.05; N, 5.40.
Found: C, 74.10; H, 5.07; N, 5.38.
(E)-3-(3,4-Dimethoxyphenyl)-1-(4-((E)-(4-((E)-3-(3,4-
dimethoxyphenyl)acryloyl)-2-hydroxyphenyl)diazenyl)-
phenyl)prop-2-en-1-one (11)
Dark red solid, FT-IR (KBr, cmꢀ1): 3191, 3037, 1650, 1586.
1H NMR (200 MHz, DMSO-d6): d 8.25 (d, J ¼ 8.0, 2H, ArH), 7.84
(d, J ¼ 8.0, 2H, ArH), 7.80 (bs, 1H, ArH), 7.74 (B part of AB
system, J ¼ 15.0, 1H), 7.54 (bs, 1H, ArH), 7.32 (m, 2H, ArH),
7.10 (bs, 1H, ArH), 7.38 (A part of AB system, J ¼ 15.0, 1H),
7.05 (bs, 1H, ArH), 7.01 (m, 2H, ArH), 6,96 (s, 1H, ArH),
3.85 (s, OCH3, 3H), 3.82 (s, OCH3, 3H), 3.77 (ss, OCH3, 3H),
3.72 (s, OCH3, 3H). 13C NMR (50 MHz, DMSO-d6): d 195.26,
188.91, 162.13, 154.90, 152.12, 152.01, 149.70, 149.64, 145.71,
145.03, 143.17, 142.88, 139.67, 130.45, 128.01, 127.77, 126.60,
124.96, 124.10, 123.03, 120.80, 118.91, 118.60, 115.04, 112.19,
111.23, 56.41, 56.22. ESI/MS (m/z): [MþH]þ 579.20. Anal. calcd.
for C34H30N2O7: C, 70.58; H, 5.23; N, 4.84. Found: C, 70.55;
H, 5.20; N, 4.80.
(E)-3-(2,3-Dimethoxyphenyl)-1-(4-((E)-(4-((E)-3-(2,3-
dimethoxyphenyl)acryloyl)-2-hydroxyphenyl)diazenyl)-
phenyl)prop-2-en-1-one (8)
Dark red solid, FT-IR (KBr, cmꢀ1): 3200, 3035, 1654, 1573.
1H NMR (200 MHz, CDCl3): d 8.02 (d, J ¼ 7.4, 2H, ArH), 7.98
(d, J ¼ 7.4, 2H, ArH), 7.85 (d, J ¼ 8,6, 1H, ArH), 7.81 (d, J ¼ 8,6,
1H, ArH), 7.76 (s, 1H, ArH), 7.61 (B part of AB system, J ¼ 15.0,
1H), 7.25 (A part of AB system, J ¼ 15.0, 1H), 7.09 (m, 2H,
ArH), 6,99 (m, 2H, ArH), 6.91 (m, 2H, ArH), 3.88 (s, OCH3,
6H), 3.82 (s, OCH3, 3H), 3.71 (s, OCH3, 3H). 13C NMR (50 MHz,
CDCl3): d 196.22, 190.20, 160.18, 154.45, 153.15, 153.01,
148.93, 148.65, 143.90, 140.87, 140.10, 139.28, 138.87, 129.53,
129.04, 128.86, 128.65, 124.27, 123.23, 122.90, 120.92, 119.55,
119.13, 118.60, 115.32, 114.30, 61.46, 61.37, 55.85, 55.79.
ESI/MS (m/z): [MþH]þ 579.20. Anal. calcd. for C34H30N2O7:
C, 70.58; H, 5.23; N, 4.84. Found: C, 70.60; H, 5.21; N, 4.80.
(E)-3-(3,5-Dimethoxyphenyl)-1-(4-((E)-(4-((E)-3-(3,5-
dimethoxyphenyl)acryloyl)-2-hydroxyphenyl)diazenyl)-
phenyl)prop-2-en-1-one (12)
Dark red solid, FT-IR (KBr, cmꢀ1): 3179, 3031, 1655, 1589.
1H NMR (200 MHz, DMSO-d6): d 8.25 (bs, 1H, ArH), 7.91 (bs, 2H,
ArH), 7.83 (bs, 1H, ArH), 7.79 (bs, 1H, ArH), 7.71 (B part of AB
system, J ¼ 15.2, 1H), 7.33 (s, 1H, ArH), 7.08 (bs, 2H, ArH), 7.10
(bs, 2H, ArH), 6.95 (s, 1H, ArH), 6.87 (s, 1H, ArH), 6.59 (A part of
AB system, J ¼ 15.2, 1H), 3.78 (s, OCH3, 3H), 3.69 (s, OCH3, 3H).
13C NMR (50 MHz, DMSO-d6): d 195.33, 189.13, 162.27, 161.40,
154.95, 145.28, 144.08, 143.23, 142.10, 139.30, 137.21, 137.06,
130.64, 129.26, 123.10, 121.56, 118.83, 115.21, 107.51, 106.98,
103.73, 56.15, 56.03. ESI/MS (m/z): [MþH]þ 579.20. Anal. calcd.
for C34H30N2O7: C, 70.58; H, 5.23; N, 4.84. Found: C, 70.54;
H, 5.19; N, 4.79.
(E)-3-(2,4-Dimethoxyphenyl)-1-(4-((E)-(4-((E)-3-(2,4-
dimethoxyphenyl)acryloyl)-2-hydroxyphenyl)diazenyl)-
phenyl)prop-2-en-1-one (9)
Dark red solid, FT-IR (KBr, cmꢀ1): 3211, 3040, 1656, 1579.
1H NMR (200 MHz, CDCl3): d 8.08 (B part of AB system, J ¼ 15.0,
1H), 8.01 (d, J ¼ 7.8, 1H, ArH), 7.97 (d, J ¼ 7.8, 1H, ArH), 7.93 (bs,
2H, ArH), 7.86 (d, J ¼ 7.8, 1H, ArH), 7.82 (d, J ¼ 7.8, 1H, ArH),
7.72 (s, 1H, ArH), 7.55 (A part of AB system, J ¼ 15.0, 1H), 7.18
(bs, 2H, ArH), 6.54 (d, J ¼ 7.8, 1H, ArH), 6.41 (bs, 1H, ArH), 6.46
(s, 1H, ArH), 6.38 (s, 1H, ArH), 3.87 (s, OCH3, 3H), 3.85 (s, OCH3,
3H), 3.78 (s, OCH3, 3H), 3.70 (s, OCH3, 3H). 13C NMR (50 MHz,
CDCl3): d 196.77, 190.71, 163.25, 163.19, 160.52, 160.30,
160.28, 154.42, 143.65, 141.29, 141.72, 140.67, 139.67, 131.22,
129.62, 129.34, 126.15, 125.23, 122.85, 119.94, 116.80, 116.50,
115.22, 105.73, 105.41, 98.30, 97.85, 55.49. ESI/MS (m/z):
[MþH]þ 579.20. Anal. calcd. for C34H30N2O7: C, 70.58; H, 5.23;
N, 4.84. Found: C, 70.59; H, 5.21; N, 4.80.
(E)-1-(3-Hydroxy-4-((E)-(4-((E)-3-(2,3,4-trimethoxyphenyl)-
acryloyl)phenyl)diazenyl)phenyl)-3-(2,3,4-
trimethoxyphenyl)prop-2-en-1-one (13)
Dark red solid, FT-IR (KBr, cmꢀ1): 3153, 3028, 1635, 1579.
1H NMR (200 MHz, CDCl3): d 8.04 (d, J ¼ 7.0, 2H, ArH), 7.88
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Bischalcone Derivatives as Carbonic Anhydrase Inhibitors
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(bs, 2H, ArH), 7.87 (bs, 1H, ArH), 7.85 (bs, 1H, ArH), 7.74
(B part of AB system, d, J ¼ 15.6, 1H), 7.52 (s, 1H, ArH),
7.41 (m, 1H), 6.75 (m, 2H, ArH), 6.58 (m, 2H, ArH), 3.83
(s, OCH3, 3H), 3.72 (s, OCH3, 3H), 3.68 (s, OCH3, 3H). 13C NMR
(50 MHz, CDCl3): d 196.52, 190.32, 160.15, 155.95, 154.43,
153.83, 153.56, 143.77, 142.31, 142.17, 140.75, 139.93,
139.54, 129.43, 126.87, 124.08, 123.45, 122.85, 121.70,
121.42, 120.92, 118.43, 115.20, 107.58, 61.56, 61.43, 60.92,
56.07. ESI/MS (m/z): [MþH]þ 639.23. Anal. calcd. for
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C
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