Synthesis, characterization, and antioxidant and bleomycin-dependent DNA damage evaluation of curcumin analogs

Article abstract of DOI:10.1002/ardp.201300203

In an attempt to find a new class of antioxidant agents, a series of pyrazole, pyridopyrazoltriazine, pyrazolotriazine, isoxazole, and pyridine-containing products were prepared, starting with curcumin and appropriate chemical reagents. Thus, curcumin 1 undergoes coupling reaction with diazonium salts 2-5 to afford the corresponding 4-arylazo derivatives 6-9. Heating of 6 and/or 7 in acetic acid furnished the corresponding pyrazolotriazines 10 and 11. Also, pyrazole and isoxazole derivatives were obtained upon treatment of 10 with hydrazines or hydroxylamine hydrochloride. Furthermore, multicomponent reaction of 10 with malononitrile/CH ₃COONH₄ or phenacylpyridinium iodide/CH ₃COONH₄ produced the corresponding bispyridines 16 and 17, respectively. Furthermore, condensation of 10 with guanidine nitrate or thiourea gave the corresponding pyrimidines 18 and 19, respectively. Finally, other curcumin derivatives were obtained on condensation of 1 with isatins and pyrazole-4-aldehyde. The newly synthesized compounds were evaluated as antioxidant agents. The results showed clearly that most of the compounds exhibited good activities, except for compounds 9 and 12. Compounds 1, 3, 15, and 23 exhibited high protection against DNA damage induced by the bleomycine-iron complex. In an attempt to find a new class of antioxidant agents, a series of pyrazole, pyridopyrazoltriazine, pyrazolotriazine, isoxazole, and pyridine-containing products were prepared starting with curcumin. The newly synthesized compounds were evaluated as antioxidant agents. Most of the compounds exhibited good activities and some exhibited high protection against DNA damage induced by the bleomycine-iron complex.

Full text of DOI:10.1002/ardp.201300203

Arch. Pharm. Chem. Life Sci. 2014, 347, 123–133
123
Full Paper
Synthesis, Characterization, and Antioxidant and Bleomycin-
Dependent DNA Damage Evaluation of Curcumin Analogs
Mohamed H. M. Helal1,2, Nadia S. Ahmed3,4, Mohamed S. Elwessaly5, and Yossry A. Ammar2
1
Faculty of Arts and Science, Department of Chemistry, Northern Border University, Rafha, Saudi Arabia
Faculty of Science, Department of Chemistry, Al-Azhar University, Nasr City, Cairo, Egypt
Faculty of Education, Department of Nutrition, Northern Border University, Rafha, Saudi Arabia
Department of Chemistry, National Institute of Oceanography and Fisheres, Alx, Egypt
2
3
4
5
Department of Nutrition, Northern Border University, Arar, Saudi Arabia
In an attempt to find a new class of antioxidant agents, a series of pyrazole, pyridopyrazoltriazine,
pyrazolotriazine, isoxazole, and pyridine-containing products were prepared, starting with curcumin
and appropriate chemical reagents. Thus, curcumin 1 undergoes coupling reaction with diazonium
salts 2–5 to afford the corresponding 4-arylazo derivatives 6–9. Heating of 6 and/or 7 in acetic acid
furnished the corresponding pyrazolotriazines 10 and 11. Also, pyrazole and isoxazole derivatives were
obtained upon treatment of 10 with hydrazines or hydroxylamine hydrochloride. Furthermore,
multicomponent reaction of 10 with malononitrile/CH3COONH4 or phenacylpyridinium iodide/
CH3COONH4 produced the corresponding bispyridines 16 and 17, respectively. Furthermore,
condensation of 10 with guanidine nitrate or thiourea gave the corresponding pyrimidines 18 and
19, respectively. Finally, other curcumin derivatives were obtained on condensation of 1 with isatins
and pyrazole-4-aldehyde. The newly synthesized compounds were evaluated as antioxidant agents. The
results showed clearly that most of the compounds exhibited good activities, except for compounds 9
and 12. Compounds 1, 3, 15, and 23 exhibited high protection against DNA damage induced by the
bleomycine–iron complex.
Keywords: Antioxidant activity / Curcumin / Indole / Oxazole / Pyrazole / Pyrimidine
Received: May 27, 2013; Revised: August 29, 2013; Accepted: September 12, 2013
DOI 10.1002/ardp.201300203
Introduction
(Zingiberacea), is a perennial herb distributed mainly through-
out tropical and subtropical regions of the world. It has been
used in indigenous herbal medicine for the treatment of
inflammatory and liver disorders [2, 3]. Curcumin has potent
antioxidant, anti-inflammatory, antimutagenic, and anticarci-
nogenic properties [4–6]. The protective effects of curcumin
against chemically induced hepatotoxicity are well docu-
mented, and have been attributed to its intrinsic antioxidant
properties [7, 8]. Thus, curcumin was shown to retard lipid
peroxidation and ameliorate chemically induced oxidative
stress [9]. Curcumin is a unique antioxidant, which contains
a variety of functional groups, including the B-diketo group,
carbon–carbon double bonds, and phenyl rings containing
varying amounts of hydroxyl and methoxy substituents [10].
The antioxidant mechanism of curcumin has attracted much
attention. Generally, it has a dual effect in oxygen radical
reactions; thus, it can act as a scavenger of hydroxyl radicals
or catalyze the formation of hydroxyl radicals depending on
The area of free radical biology and medicine is developing
fast since the discovery of the involvement of free radicals in
oxidative tissue in diseases. Free radicals and other reactive
oxygen species such as superoxide radical anion, hydroxyl
radical, and hydrogen peroxide are constantly generated
through many biological processes and may be considered as
a measure of biological inefficiency. The human body uses an
antioxidant system to neutralize the excessive levels of
reactive oxygen species that consists of enzymes [1]. Curcumin
(deferuloymethane), a yellow coloring ingredient of the spice
turmeric obtained from the rhizome of Curcuma longa Linn
Correspondence: Mohamed H. M. Helal, Faculty of Science, Department
of Chemistry, Al-Azhar University, 11284 Nasr City, Cairo, Egypt.
E-mail: m.h.helal.chem@gmail.com
Fax: þ966 567227904
ß 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

124
M. H. M. Helal et al.
Arch. Pharm. Chem. Life Sci. 2014, 347, 123–133
the experimental conditions [11–15]. Curcumin is stable at Results and discussion
a pH below 6.5. The instability of curcumin at a pH above 6.5 is
attributed to the active methylene group. Omitting the active
methylene group and one carbonyl group may lead to potent
antioxidative compounds [16]. Some synthetic analogs,
also proved to possess antioxidant activity, appear to block
activation of chemical carcinogenesis and prevent the
initiation phase [17–21]. Most of the aforementioned drugs
possess phenolic hydroxyl groups and an enol form of a
b-diketone moiety. Those functional groups are believed to
be contributing to the antioxidant chemopreventive activity
[22, 23]. In view of the above-mentioned facts and in
continuation of our interest in the synthesis of biologically
active heterocycles [24–28], we report herein the synthesis and
antioxidant evaluation of some novel structure hybrids
incorporating both the curcumin moiety with either the
pyrazole, pyridine, or triazine ring systems through different
linkages. This combination was suggested in an attempt to
investigate the influence of such hybridization and structure
variation on the anticipated biological activities, hoping to
reach a more potent antioxidant agent.
Chemistry
The target compounds were synthesized as outlined in
Schemes 1–4. Detailed synthetic procedures for all com-
pounds are described in the Experimental section. Derivatives
of hydroxyarylazobenzene are well known as dyes [29–31],
Fadda and coworkers [32] also reported the coupling of
diazonium salt of different aromatic amines with curcumin 1
and synthesized new azodisperse dyes that are capable of
dyeing different types of fibers and have expected wide
spectrum of biological activity. Consequently, the authors
decided to couple the diazonium salt of different pyrazoles
2–5 with curcumin 1 to give the corresponding 4-arylazo
derivatives 6–9. Elemental analysis and spectral data were in
favor of this proposed thiazole structure. The IR spectrum of 6
showed absorption bands at 3408, 3250, and 1670 cmꢀ1 due to
OH, NH, and carbonyl groups, respectively. The 1H NMR
spectrum revealed signals at 2.70 and 2.99 due to the methyl
protons of pyridine ring together with two singlet signals
exhibited in the region at 3.81 and 3.857 ppm corresponding
CH3
O
O
N2Cl
2
O
O
N
H3C
N
N
H
N
HO
OH
CH3
N
NH
pyridine
N
6
H3C
N
H
CH3
N
N
H3C
O
O
N
O
O
N2Cl
N
N
O
HO
H3C
OH
N
H3C
N
H
CH3
NH
3
N
pyridine
N
N
N
7
N
O
O
O
N
H3C
H
O
O
OCH3
O
O
HO
OH
1
O
O
N
H3C
H3C
HO
OH
N2Cl
4
HN
N
N
N
N
H
NH
8
pyridine
H3CO
N
H3C
O
CH3
N2Cl
O
N
O
O
N
N
H
5
N
HO
OH
N
H
NH
N
pyridine
H
9
N
H
Scheme 1. Structural formulas of compounds 6–9.
ß 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

Arch. Pharm. Chem. Life Sci. 2014, 347, 123–133
Antioxidant Activity of Novel Curcumins
125
OH
N
of 10 displayed the lack of absorption band assignable to the
NH group. The 1H NMR spectrum displayed two singlet signals
at 2.61 and 2.83 ppm corresponding to two methyl protons
and another two singlets at 3.80 and 3.86 assignable to two
methoxy groups and a multiplet signal at 6.85–8.25 related to
O
N
O
O
–
the aromatic protons in addition to the two CH CH protons.
AcOH
–
6
N
HO
Moreover, the mass spectrum showed a molecular ion peak at
(Mþ) at m/z 523 corresponding to the molecular formula
N
N
O
10
CH3
H3C
C29H25N5O5. Furthermore, acetylation of compound 10 with
OAc
acetic anhydride achieved the diacetyl 12. The structure of the
diacetyl derivative 12 was identified as the reaction product
on the basis of its elemental analysis and spectroscopic data.
Its IR spectrum displayed the lack of absorption band
assignable to the OH group and the presence of new
absorption bands at 1674 and 1667 cmꢀ1 corresponding to
Ac2O
O
O
N
N
N
AcO
1
N
N
–
C O groups. The H NMR spectrum displayed broad singlet
–
CH3
signals at 2.16 and 2.18 ppm corresponding to the two acetyl
protons. In addition, the mass spectrum showed a molecular
ion peak at (Mþ) m/z at 607 corresponding to a molecular
formula C33H29N5O7.
H3C
12
OH
O
In continuation of our search toward the design and
synthesis of heterocyclic analogs of pyridine [33–37] as
potential chemotherapeutic agents, it was decided to take
10 as adaptable starting material for the synthesis of new
heterocyclic binary system with the hope that the new
compounds may exert more potent effect. Also, the behavior
of compound 10 toward some N-nucleophiles to attain
polyfunctionally substituted azoles, azines, and related fused
systems linked to a pyridotiazine moiety of potential
pharmaceutical interest has been investigated. Thus, treat-
ment of 10 with hydrazine hydrate and/or phenyl hydrazine
in acetic acid afforded the corresponding pyrazoline deriv-
atives 13 and 14, respectively. The spectral data of the isolated
product were in complete agreement with structures 13 and
14. The IR spectrum of 13 showed absorption bands at 3331,
O
O
N
N
N
N
CH3
O
HO
N
AcOH
7
N
N
NH
H3C
11
Scheme 2. Structural formulas of compounds 10–11.
to the two methoxy groups. The mass spectrum revealed the
molecular ion peak at m/z 541 (M) corresponding to the
molecular formula C29H27N5O6.
Upon heating the pyrazolohydrazono derivative 6 or 7 in
acetic acid caused cyclization to afford the corresponding
pyrazolotriazine derivatives 10 and 11. The structures of 10
and 11 were identified as the reaction products on the basis of
their elemental analyses and spectroscopic data. IR spectrum
1657, and 1564 cmꢀ1 corresponding to OH, amidic C O, and
–
–
N N functions, respectively. The 1H NMR spectrum of 13
–
–
showed a singlet signal at 2.14 corresponding to COCH3;
besides three doublet signals at 3.86, 3.96, and 5.05 ppm with
OH
O
OH
O
R
N
N
O
N
NH2NH2.H2O
or PhNHNH2
NH2OH.HCl
pyridine
O
O
N
N
10
N
N
N
N
HO
N
N
HO
N
N
CH3
CH3
H3C
H3C
13, R = COCH3
14, R = Ph
15
Scheme 3. Structural formulas of compounds 13–15.
ß 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

126
M. H. M. Helal et al.
Arch. Pharm. Chem. Life Sci. 2014, 347, 123–133
OH
O
OH
N
O
X
R1
R2
N
HN
N
N
(NH2)2C=NH .HNO3
CH2(CN)2
O
O
pyridine
ammacetate
N
N
N
10
N
or thiourea/KOH
HO
N
N
or PhCOCH2 Py I
amm.acetate
HO
N
N
CH3
CH3
H3C
H3C
16, R1 = NH2, R2 = CN
17, R1 = Ph, R2 = H
OH
N
O
XH
N
N
O
N
N
HO
N
N
CH3
H3C
18, X = NH
19, X = S
Scheme 4. Structural formulas of compounds 16–19.
coupling constant (J ¼ 12, 7.8 Hz), respectively assignable to
pyrazoline protons, the mass spectrum showed a molecular
ion peak at m/z ¼ 577 (Mꢀ2), corresponding to molecular
formula C31H29N7O5. Similarly, the reaction of 10 with
hydroxylamine hydrochloride in refluxing pyridine afforded
the isoxazoline derivative 15. The isoxazoline 15 may be
rationalized through the first condensation followed by
nucleophilic addition of OH group to the double bond. The
structures of the isolated products were elucidated on the
potassium hydroxide, respectively. Elemental analysis and
spectral data were in agreement with the formation of the
pyrimidine products 18 and 19. 1HNMR spectrum of
compound 18 showed a new singlet signal at 8.34 and a
broad at 8.66 corresponding to CH-pyrmidine and NH2
protons, respectively. The mass spectrum showed a molecu-
lar ion peak at m/z 562 (1.1) corresponding to the molecular
formula C30H26N8O4. Formation of compounds 18 and 19
may be assumed to proceed via the condensation of the
amino group of the guanidine and/or thiourea with the
carbonyl group, then interamolecular cyclization to form
the target compounds.
In continuation of this study for the combination of
curcumin with biologically active moieties, we report here the
use of compound 1 as a key intermediate for the synthesis of
new series of curcumin. Thus, condensation of 1 with
substituted isatin was performed in molar ratio (2:1) in
boiling ethanol, containing piperidine as a catalyst, to give
the corresponding spiro derivatives 21–23 (Scheme 5). The
chemical structure of 21–23 was supported on the basis of
elemental analysis and spectral data.
1
basis of their spectral data (IR, MS, and H NMR).
Multicomponent reaction of 10 with malononitrile and
ammonium acetate or phenacylpyridinium iodide and
ammonium acetate in glacial acetic acid afforded in each
case a product that was identified as the pyridine derivatives
16 and 17, respectively. The structure of compound 16 was
assigned on the basis of the elemental analysis and spectral
data. The IR spectrum showed absorption bands at 3360 and
3227 cmꢀ1, corresponding to NH2 and at 2204 cmꢀ1 due to
CN function. The 1H NMR spectrum of compound 16
revealed two broad singlet signals at d 2.68 and 2.84 ppm
assignable to two CH3 protons and broad signal at d
9.48 ppm due to NH2 proton. The mass spectrum showed a
molecular ion peak (Mþ) at m/z ¼ 584, corresponding to the
molecular formula C32H26N8O4. The aminopyrimidine or
thioxopyrimidines 18 and 19 were achieved as a sole
product in each case by heating compound 10 guanidine
nitrate in pyridine or thiourea in boiling ethanolic
Finally, reaction of 1 with 5-chloro-3-methyl-1-phenyl-
1H-pyrazole-4-carbaldehyde 24 [24] and ammonium
acetate caused cyclocondensation to furnish the pyrazolo-
pyridine derivative 25 (Scheme 6). However, repeating
this reaction in the presence of piperidine or morpholine
afforded the pyrazolyl derivatives 26 and 27 (Scheme 6)
ß 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

Arch. Pharm. Chem. Life Sci. 2014, 347, 123–133
Antioxidant Activity of Novel Curcumins
127
O
by Lissi et al. [25]. The antioxidant activity assay employed
here is one of the several assays that depend on measuring the
consumption of stable free radicals, i.e., evaluating the free
radical scavenging activity of the investigated component.
The methodology assumes that the consumption of the stable
free radical (X0) will be determined by the reaction as follows:
O
O
O
R
HO
R
O
OH
1 +
HN
N
H
HO
O
OH
O
_
O
O
20a c
XH þ Y0 ! X0 þ YH
O
O
21, R = H
22, R = CH3
23, R = Cl
The rate and/or the extent of the process measured in terms
of the decrease in X0 concentration would be related to the
ability of the added compounds to trap free radicals. The
decrease in color intensity of the free radical solution due to
scavenging of the free radical by the antioxidant material is
measured calorimetrically at a specific wavelength. The assay
employs the radical cation derived from 2,20-azino-bis(3-ethyl
benzthiazoline-6-sulfonic acid) (ABTS) as stable free radical to
assess antioxidant potential of the investigated compounds.
Some of the compounds displayed antioxidant activity
compared with ascorbic acid as shown in Table 1. Compounds
9 and 12 showed weak antioxidant activity, while compounds
6, 16, and 25 showed moderate antioxidant activity; on the
other hand, compounds 1, 7, 10, 13, 14a, 15, 21, and 23
displayed high antioxidant potency. Compound 1 exhibited a
high antioxidant activity compared with ascorbic acid and
other compounds.
Scheme 5. Structural formulas of compounds 20–23.
O
OH
O
O
amm.acetate
ethanol
N
HO
N
N
H3C
25
O
O
H3C
(1) +
CHO
Cl
O
O
H
N
N
HO
OH
N
H3C
N
N
N
ethanol
26
24
O
O
O
O
H
N
Table 1. ABTS antioxidant activity assay of the new compounds.
HO
OH
H3C
N
O
O
N
N
Absorbance of
Compound no.
samples (l)
% Inhibition
ethanol
27
Control of ABTSa)
0.496
0.044
0.011
0.126
0.094
0.321
0.049
0.050
0.307
0.020
0.049
0.031
0.101
0.060
0.080
0.058
0.041
0.048
0.026
0.110
0.062
0.047
0
Ascorbic acid
1
6
7
91.12
97.78
74.59
81.04
35.28
90.12
89.91
38.10
95.96
90.12
93.75
79.63
87.90
83.87
88.30
91.73
90.32
94.75
77.82
87.50
90.52
Scheme 6. Structural formulas of compounds 24–27.
9
whereas consumpation of piperidine and morpholine in the
reaction is an evidence for the assigned structures. For
example, the IR spectrum of compound 26 showed the
appearance of absorption bands at 3412 and 1659 cmꢀ1
corresponding to the hydroxyl and carbonyl groups. The
1H NMR spectrum exhibited two multiplet signals at
1.87 and 2.98 ppm assignable to the protons of piperidine
10
11
12
13
14
15
16
17
18
19
21
22
23
25
26
27
group. The mass spectrum showed
peak at m/z 619 corresponding to the molecular formula
37H37N3O6, with a peak at m/z 84 corresponding to the
a molecular ion
C
piperidine moiety.
Biological evaluation
ABTS antioxidant assay
The newly synthesized compounds were screened for their
a)
ABTS: the method used for antioxidant activity.
antioxidant activity using ABTS method, which was reported
(%) Inhibition ¼ [A (control) ꢀ A (test)/A (control)] ꢁ 100.
ß 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

128
M. H. M. Helal et al.
Arch. Pharm. Chem. Life Sci. 2014, 347, 123–133
The antioxidant mechanism
attributed to the conversion of hydroxyl group into acetyl
group through acetylation reaction.
Curcumin is a well-known natural antioxidant and cancer
chemopreventive agent, which has attracted much interest in
the past decade. Effective effort has, therefore, been continu-
ously devoted to the synthesis of new curcumin analogs,
aiming at finding more effective antioxidants and cancer
chemopreventive agents [38]. The antioxidant mechanisms of
curcumin have recently been a focus of interest of free radical
chemists and biologists [39–42]. Barclay and collaborators
compared the antioxidant activity of curcumin and dime-
thylcurcumin against free radical initiated peroxidation of
styrene in chlorobenzene solution and concluded that
curcumin is a classical phenolic chain-breaking antioxidant,
donating H atoms from the phenolic groups [40]. Theoretical
calculations by density functional theory demonstrated that
the enol form of curcumin is significantly more stable than
the diketo form and that the bond dissociation enthalpy (BDE)
of the phenolic O–H bond is significantly lower than the BDE
of the central C–H bond, suggesting that the H-atom
abstraction shall take place in the phenolic group [11, 41,
43]. Recently Priyadarsini and coworkers also compared the
antioxidant activity of curcumin and dimethylcurcumin
against radiation-induced lipid peroxidation of rat liver
microsomes and the free radical scavenging activity against
2,2-diphenyl-1-picrylhydrazyl, and concluded that the pheno-
lic group plays a major role in the activity of curcumin [43].
Moreover, the methoxyphenolic moiety has also been reported
to be an essential structural feature contributing antioxidant
activity [44]. It has been proved that the ortho-methoxyl group
can form intramolecular hydrogen bond with the phenolic
hydrogen, making the H-atom abstraction from the ortho-
methoxyphenols surprisingly easy (Scheme 7) [45]. Finally, it
was also pointed out that the relative contribution of the
phenolic group and the central methylenic group on the
antioxidant activity depends on the activity of the attacking
radical and the reaction medium [11, 42].
Structure–activity relationship (SAR)
By comparing the results obtained for the antioxidant activity
of the compounds reported in this study with their structures,
the following structure SARs were postulated:
i. Compounds 1, 13, 15, 21, 22, and 23 have comparatively
higher antioxidant activity than ascorbic acid, which may
be attributed to the presence of OH, methoxy, pyrazole,
oxazole, and indole moieties.
ii. Cyclization of the hydrazone derivatives 6 and 7 into the
triazine derivatives 11 and 12, respectively, enhance the
biological activity.
iii. Compounds 23 > 21 > 22 may be attributed to decrease
in the mesomeric effect (Mþ) as follows: Cl < H < CH3.
iv. Compound 1 exhibited good antioxidant activity com-
pared to the new synthesized compounds, which may be
due to the presence of two free a,b-unsaturated ketones.
v. Compounds bearing ortho-diphenoxyl and/or ortho-
methoxyphenoxyl groups exhibit remarkably higher
antioxidative activity than the ones bearing no such
functionalities, which gives us useful information for
antioxidant drug design.
vi. The introduction of a heterocyclic ring like pyrazole,
trizaine, oxazole, and indole rings enhances the antioxi-
dant activity and gives us useful information for
antioxidant drug design. This in agreement with the
results reported in literature [46, 47].
Bleomycin-dependent DNA damage assay
The bleomycins are a family of glycopeptide antibiotics that
was used routinely as antitumor agents. The bleomycin assay
was adopted for assessing the pro-oxidant effects of food
antioxidants. The antitumor antibiotic bleomycin binds iron
ions and DNA. The bleomycin iron complex degrades DNA
that, upon heating with thiobarbituric acid (TBA), yields a
pink chromogen. Upon the addition of suitable reducing
agents, antioxidants compete with DNA and diminish
chromogen formation [26]. The protective activity against
DNA damage induced by bleomycin iron complex was
examined in order to show the mechanism of action of the
potent compounds 1, 10, 13, 14, 15, 21, 22, 23, and 27. The
results in Table 2 showed that compounds 1, 3, 15, and 23
exhibited high protection against DNA damage induced by
the bleomycin–iron complex, thus diminishing chromogen
formation between the damaged DNA and TBA molecules.
By comparing the results obtained for the antioxidant
properties of the compounds reported in this study with their
structures, the following structure–activity relationships
(SARs) were postulated (Fig. 1): (i) Curcumins 1, 13, 15, 21,
and 23 are more potent than ascorbic acid, which may be
Compounds 6, 16, and 25 showed moderate antioxidant
activity while compounds 1, 7, 10, 13, 14a, 15, 21, 22, and 23
displayed high antioxidant potency. The antioxidant activity
of compounds 21, 22, and 23 might be explained by the
presence of 4-OH and 4-methoxy substitutions, which
enhanced their radical scavenging activity by the stabilized
phenoxy radical. The poor activity of compound 12 may be
Scheme 7. Intermolecular hydrogen bond for o-methoxy phenolic
compounds.
ß 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

Arch. Pharm. Chem. Life Sci. 2014, 347, 123–133
Antioxidant Activity of Novel Curcumins
129
Table 2. Bleomycin-dependent DNA damage of the investigated
compounds.
containing products were prepared starting with curcumin
and had been evaluated as antioxidant agents. The results
showed clearly that most of the synthesized compounds
exhibited good activities and some of them exhibited high
protection against DNA damage induced by the bleomycine–
iron complex.
Compound no.
Absorbance of samples
Ascorbic-acid
1
0.078
0.052
0.102
0.067
0.115
0.077
0.081
0.093
0. 069
0.086
10
13
14
15
21
22
23
27
Experimental
All melting points are in degree centigrade (uncorrected) and
were determined on a Gallenkamp electric melting point
apparatus. TLC analysis was carried out on silica gel precoated
aluminum sheets. The IR spectra were recorded (KBr) on a
Mattson 5000 FTIR spectrophotometer (l, cmꢀ1) in the Micro-
analytical Center (Faculty of Science, Mansoura University). The
1H NMR spectra were determined on a JEOL spectrophotometer at
500 MHz, using TMS as an internal reference and DMSO-d6 as
solvent and were carried out in the National Research Center,
Dokki, Giza, Egypt. The mass spectra (EI) were recorded on a
Varian Star 3400 Cx Ion Trap GC/MS Shimadzu GCMS-QP 5050 A
EI (70 eV) at the Regional Center for Mycology and Biotechnology,
Al-Azhar University. Elemental analyses (C, H, and N) were carried
out at the Microanalytical Center of Cairo University, Giza, Egypt.
The elemental analyses were found to agree favorably with the
calculated values. Biological activities were assessed in Pharma-
cognosy Department, Faculty of Pharmacy, Mansoura University,
Mansoura, Egypt.
attributable to the presence of hydroxyl, pyrazole, oxazole,
and indole moiety, respectively. (ii) Cyclization of the
hydrazone derivatives 6 and 7 into the triazine derivatives
11 and 12, respectively, enhances the biological activity,
which may be due to the presence of triazine moiety. (iii)
Compound 11 was less potent than 10, which may be due to
the disappearance of OH moiety. (iv) Compounds 23 > 21 > 22
may be attributed to decrease the mesomeric effect (þM) as
follows: Cl < H < CH3. (v) Compound
1 exhibited good
antioxidant activity compared to the newly synthesized
compounds, which may be due to the presence of two free a,b-
unsaturated ketone moieties.
General procedure for the synthesis of 6–9
A
well-stirred solution of 3-amino-4,6-dimethyl-2H-pyrazolo-
[3,4-b]pyridine 2 (5 mmol), 4-(5-amino-3-methyl-1H-pyrazol-4-yl)-
diazenyl)-2,3-dimethyl-1-phenyl-1,2-dihydropyrazol-5-one 3 (5 mmol),
3-amino-4-(4-methoxyphenyl)-5,6-dimethyl-1H-pyrazolo[3,4-b]pyridine
4 (5 mmol), 5-amino-3-(1H-indol-3-yl)-1H-pyrazol 5 (5 mmol), in a
mixture of acetic acid (10 mL) and concentrated HCl (3 mL), was
Conclusion
In conclusion, a series of pyrazole, pyridopyrazoltriazine,
pyrazolotriazine, isoxazole, and other related pyridine-
0.14
0.12
0.1
Standard deviation = 0.01
0.08
0.06
0.04
0.02
0
Ascorbic-
acid
1
10
13
14
15
21
22
23
27
Compounds
Figure 1. Antioxidant activity of curcumin compounds.
ß 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

130
M. H. M. Helal et al.
Arch. Pharm. Chem. Life Sci. 2014, 347, 123–133
cooled in an ice bath and then a solution of NaNO2 (5.8 mmol in 5 mL
H2O) was added drop wise. The above cooled diazonium solution was
added slowly to a well-stirred solution of curcumin 1 (5 mmol) in
pyridine (25 mL). The reaction mixture was stirred for 2 h. The crude
product was filtered off, dried well, and crystallized from EtOH/DMF
to give compounds 6–9, respectively.
for C32H27N5O6 (577.59): calcd. C, 66.54; H, 4.71; N, 12.13%. Found:
C, 66.73; H, 4.82; N, 12.34.
Synthesis of pyrazolotriazines (10 and 11)
A suspension of arylhydrazo derivatives 6 or 7 (5 mmol) in acetic
acid (10 mL) was refluxed for 12 h. The reaction mixture was
poured into ice-cold water; then the formed precipitate was
filtered off, dried, and recrystallized from a mixture of DMF/
ethanol to give compounds 10 and 11, respectively.
(4-(2-(4,6-Dimethyl-1H-pyrazolo[3,4-b]pyridin-3-yl)-
hydrazono)-1,7-bis(4-hydroxy-3-methoxy-phenyl)-
hepta-1,6-diene-3,5-dione (6)
Yield 87%; m.p.: 275°C; IR (KBr): n/cmꢀ1 ¼ 3408 (br, 2OH), 3250
7-(3-(4-Hydroxy-3-methoxyphenyl)-1-oxo-prop-2-en-1-yl)-
8-(2-(4-hydroxy-3-meth-oxyphenyl)ethen-1-yl)-2,4-
(br, 2NH), 1670 (2C O), 1608 (C C); 1H NMR (DMSO-d6):
–
–
–
–
d ppm ¼ 2.70, 2.99 (2s, 6H, 2CH3-pyridine), 3.81, 3.85 (2s, 6H,
dimethyl-1,5,6,8a,9-pentaazafluorene (10)
Yield 85%; m.p.: 214°C; IR (KBr): n/cmꢀ1 ¼ 4419 (br, 2OH), 1654
–
2OCH ), 6.77 (br, 2H, 2OH), 6.81–7.82 (m, 11H, Ar–H þ 2CH CH),
–
3
(br, C O), 1590 (C C), 1512 (N N); 1H NMR (DMSO-d6):
9.90 (s, 1H, NH-pyrazole), 13.29 (s, 1H, NH-hydrazone); MS: m/z
(%) ¼ 541 (3.5, Mþ1), 512 (4.6), 434 (2.3), 407 (2.3), 358 (3.5), 298
(2.3), 242 (2.3),198 (2.3), 160 (2.3), 141 (2.3), 116 (2.3), 100 (3.5), 91
(8.1), 77 (12.6), 52 (57.5). Anal. for C29H27N5O6 (541.6): calcd. C,
64.32; H, 5.03; N, 12.93%. Found: C, 64.21; H, 5.01; N, 12.94.
–
–
–
–
–
–
d ppm ¼ 2.61, 2.83 (2s, 6H, CH3-pyridine), 3.80, 386 (2s, 6H,
–
–
2OCH ), 6.65 (br.s, 2H, 2OH), 6.85–8.25 (m, 11H, Ar–H þ 2CH CH);
3
MS: m/z (%) ¼ 523 (0.1, Mþ), 487 (0.2), 449 (0.2), 378 (0.8), 247 (4.3),
232 (3.9), 320 (14.5), 192 (5.6), 177 (6.2), 150 (43.2), 124 (100), 109
(37.3), 94 (13.2), 81 (31.6), 77 (15.3), 52 (12.0). Anal. for C29H25N5O5
(523.2): calcd. C, 66.53; H, 4.81; N, 13.38%. Found: C, 66.42; H, 4.93;
N, 13.38.
4-(2-(4-((1,5-Dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-
pyrazol-4-yl)diazenyl)-5-methyl-1H pyrazol-3-yl)-
hydrazono)-1,7-bis(4-hydroxy-3-methoxyphenyl)-
4-(4-(4-Hydroxy-3-methoxystyryl)-3-((E)-3-(4-hydroxy-3-
methoxyphenyl)acryloyl)-7-methylpyrazolo[5,1-c][1,2,4]-
triazin-8-yl)diazenyl)-1,5-dimethyl-2-phenyl-1H-pyrazol-
hepta-1,6-diene-3,5-dione (7)
Yield 68%; m.p.: 190°C; IR (KBr): n/cmꢀ1 ¼ 3437 (br, 2OH), 3250,
ꢀ1
1
–
–
–
–
3240 (2NH), 1654 (br, 2C O), 1610 (C C), 1580 cm (–N N–); H
–
–
3(2H)-one (11)
NMR (DMSO-d6): d ppm ¼ 2.45 (s, 3H, CH3, antipyrine), 2.66 (s, 3H,
CH3-pyrazole) 3.22 (s, 3H, N-CH3-antipyrine), 3.81, 3.91 (2s, 6H,
Yield 78%; m.p.: >315°C; IR (KBr): n/cmꢀ1 ¼ 3406 (br, 2OH), 1663,
1652 (2CO), 1600 (C C), 1513 (N N); 1H NMR (DMSO-d6):
–
–
–
–
–
2OCH ), 6.60 (br, 2H, 2OH), 6.88–8.50 (m, 15H, Ar–H, 2CH CH),
–
3
9.01 (s, 2H, NH pyrazole), 10.05 (s, 1H, NH hydrazone); MS: m/z
(%) ¼ 689 (3.5, Mꢀ1), 356 (Mþ, 55%), 162 (100%), 530 (66.7), 484
(33.3), 464 (33.3), 445 (33.3), 423 (33.3), 290 (33.3), 237 (33.3), 195
(33.3), 164 (33.3), 102 (33.3), 67 (33.3), 63 (100). Anal. for
C36H34N8O7 (690.7): calcd. C, 62.60; H, 4.96; N, 16.22%. Found:
C, 62.32; H, 5.03; N, 16.12.
d ppm ¼ 2.37, 246 (2s, 6H, 2CH3), 3.21 (s, 3H, N-CH3), 3.84, 3.92
(2s, 6H, 2OCH3), 6.64 (br.s, 2H, 2OH), 6.86–8.35 (m, 15H,
–
Ar–H þ 2CH CH); MS: m/z (%) ¼ 658 (0.1, M-CH ), 632 (0.2), 589
–
3
(4.4), 504 (8.7), 468 (4.4), 438 (4.4), 387 (8.7), 342 (4.4), 312 (4.4), 255
(4.3), 146 (4.4), 132 (8.7), 113 (8.7), 94 (8.7), 67 (21.7), 77 (17.4), 52
(100). Anal. for C36H32N8O6 (672.69): calcd. C, 64.28; H, 4.79; N,
16.66%. Found: C, 64.20; H, 4.85; N, 16.51.
4-(2-(4-(4-Methoxyphenyl)-5,6-dimethyl-1H-pyrazolo-
[3,4-b]pyridin-3-yl)hydraz-ono)-1,7-bis(4-hydroxy-3-
7-(3-(3-Methoxyphenyl-4-acetate)-1-oxo-prop-2-en-1-yl)-
8-(2-(3-methoxyphenyl-4-acetate)ethen-1-yl)-2,4-
dimethyl-1,5,6,8a,9-pentaazafluorene (12)
methoxyphenyl)hepta-1,6-diene-3,5-dione (8)
Yield 78%; m.p.: 219°C; IR (KBr): n/cmꢀ1 ¼ 3437 (br, 2OH), 3250,
3240 (2NH), 1654 (br, 2C O), 1610 (C C); 1H NMR (DMSO-d6):
–
–
–
–
A suspension of pyridopyrazotriazine 10 (1 mmol) in acetic
anhydride (5 mL) was refluxed for 12 h. The reaction mixture was
poured into ice-cold water; then the formed precipitate was
filtered off, dried, and recrystallized from a mixture of DMF/
ethanol to give compound 12.
d ppm ¼ 2.61 (s, 3H, CH3), 2.82 (s, 3H, CH3), 3.76, 3.86, 3.95 (3s, 9H,
–
3 OCH ), 6.58 (br, 2H, 2OH), 6.75–8.21 (m, 14H, Ar–H þ 2CH CH),
–
3
9.66 (br, 1H, NH-pyrazole), 10.03 (s, 1H, NH-hydrazone); MS: m/z
(%) ¼ 634 (0.5, M-CH3), 582 (0.5), 497 (1.0), 387 (0.5), 290 (1.0), 259
(1.0), 187 (2.0), 157 (5.4), 119 (4.4), 67 (100), 52 (50.0). Anal. for
C36H33N5O7 (647.68): calcd. C, 66.76; H, 5.14; N, 10.81%. Found: C,
66.96; H, 5.34; N, 10.66.
Yield 82%; m.p.: 197°C; IR (KBr): n/cmꢀ1 ¼ 1674, 1668, 1653
1
–
–
–
(3 CO), 1600 (C C), 1567 (N N); H NMR (DMSO-d ): d ppm ¼ 2.16,
–
6
2.18 (2s, 6H, 2CH3CO), 2.59, 2.72 (2s, 6H, 2CH3-pyridine), 3.74, 3.90
–
–
(2s, 6H, 2OCH ), 6.88–7.98 (m, 11H, Ar–H þ 2CH CH); MS: m/z
3
(%) ¼ 616 (0.1, Mþ1/2H2O), 571 (0.2), 554 (4.4), 513 (8.7), 423 (4.4),
364 (4.4), 320 (8.7), 272 (4.4), 217 (4.4), 191 (4.3), 177 (4.4), 137 (8.7),
131 (8.7), 119 (8.7), 107 (21.7), 91 (12.5), 77 (17.4), 52 (100). Anal. for
C33H29N5O7 (607.61): calcd. C, 65.23; H, 4.81; N, 11.53%. Found: C,
65.54; H, 4.43; N, 11.76.
4-(2-(5-(1H-indol-3-yl)-1H-pyrazol-3-yl)hydrazono)-1,7-
bis(4-hydroxy-3-methoxy-phenyl)hepta-1,6-diene-3,5-
dione (9)
Yield 72%; m.p.: >315°C; IR (KBr): n/cmꢀ1 ¼ 4416 (br, 2OH), 3386,
3237 (3NH), 1662 (br, 2C O), 1592 (C C); 1H NMR (DMSO-d6):
–
–
–
–
d ppm ¼ 3.83, 3.91 (2s, 6H, 2OCH3), 6.83 (s, 2H, 2OH), 6.98–8.38
General procedure for the synthesis of
pyrazolotriazines (13 and 14)
–
(m, 16H, Ar–H þCH CH), 10.08 (s, 1H, NH, indole), 11.86 (br, 1H,
–
NH pyrazole), 12.72 (s, 1H, NH hydrazone); MS: m/z (%) ¼ 576 (1.0,
Mꢀ1) 569 (1.3), 438 (1.0), 275 (3.3), 226 (1.0), 173 (2.3), 151 (9.3),
139 (54.6), 119 (41.9), 102 (12.9), 90 (24.5), 75 (79.8), 54 (100). Anal.
A
mixture of compound 10 (1 mmol), hydrazine hydrate
(1.2 mmol) or phenylhydrazine (1.2 mmol) in glacial acetic acid
ß 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

Arch. Pharm. Chem. Life Sci. 2014, 347, 123–133
Antioxidant Activity of Novel Curcumins
131
(10 mL) was refluxed for 8 h, left to cool, diluted with water, and
the obtained solid products were crystallized from ethanol/DMF
to give products 13 and 14.
solid product obtained was filtered off and crystallized from
ethanol/DMF to give 16.
Yield 65%; m.p.: 227°C; IR (KBr): n/cmꢀ1 ¼ 3430 (br, 2OH), 3360,
–
–
–
–
3227 (NH ), 2204 (CN), 1628 (C N), 1602 (C C), 1574 (N N);
–
–
2
1H NMR (DMSO-d6): d ppm ¼ 2.68, 2.84 (2s, 6H, 2CH3-pyridine),
7-(4,5-Dihydro-1-acetyl-5-(4-hydroxy-3-methoxyphenyl)-
pyrazol-3-yl)-8-{(E)-2-{(4-hydroxy-3-methoxyphenyl)-
ethen-1-yl}-2,4-dimethyl-1,5,6,8a,9-pentaazafluorene (13)
3.81, 3.85 (2s, 6H, 2OCH3), 6.72 (br.s, 2H, 2OH), 6.83–8.03 (m, 10H,
–
–
Ar–H þ CH CH), 9.48 (br, 2H, NH ); MS: m/z (%) ¼ 584 (Mꢀ2, 16.2),
2
281 (17.5), 216 (15.5), 194 (16.7), 138 (18.3), 124 (22.2), 108 (40.2),
92 (26.6), 81 (43.4), 77 (40.2), 64 (19.2), 52 (100). Anal. for
Yield 58%; m.p.: 219°C; IR (KBr): n/cmꢀ1 ¼ 3331 (br, 2OH), 1657
1
–
–
–
–
(C O),1599 (C C), 1564 (N N); H NMR (DMSO-d ): d ppm ¼ 2.14
–
–
6
C32H26N8O4 (586.6): calcd. C, 65.52; H, 4.47; N, 19.10%. Found: C,
(s, 3H, CH3CO), 2.58, 2.69 (2s, 6H, 2CH3-pyridine), 3.78, 3.83
(2s, 6H, 2OCH3), 3.86 (dd, J ¼ 12.0, 5 Hz, 1H, pyrazoline), 3.96
(dd, J ¼ 7.8, 5 Hz, 1H, pyrazoline), 5.05 (dd, J ¼ 7.8, 5 Hz, 1H,
65.31; H, 4.25; N, 19.23.
7-(6-(4-Hydroxy-3-methoxyphenyl)-2-phenylpyridine-4-yl)-
8-(2-(4-hydroxy-3-methoxyphenyl)ethen-1-yl)-2,4-
dimethyl-1,5,6,8a,9-pentaazafluorene (17)
–
–
pyrazoline), 6.80 (br, 2H, 2OH), 6.88–8.08 (m, 9H, Ar–H þ CH CH);
MS: m/z (%) ¼ 577 (2.7, Mꢀ2), 407 (2.6), 364 (79.8.2), 351 (6.7), 320
(13.9), 271 (4.4), 326 (9.3), 167 (5.0), 150 (42.6), 137 (100), 124 (46.8),
109 (22.3), 94 (14.9), 81 (52.8), 77 (25.6), 52 (29.8). Anal. for
C31H29N7O5 (579.6): calcd. C, 64.24; H, 5.04; N, 16.92%. Found: C,
64.35; H, 5.23; N, 16.85.
A mixture of 10 (2 mmol), phenacylpyridinium iodide (2 mmol),
and ammonium acetate (4 mmol) in acetic acid (20 mL) was
refluxed for 18 h. The reaction mixture was diluted with water
and then basified by ammonium hydroxide. The solid product
obtained was filtered, crystallized from ethanol/DMF to give 17.
Yield 81%; m.p.: >315°C; IR (KBr): n/cmꢀ1 ¼ 3373 (br, 2OH),
7-(4,5-Dihydro-1-phenyl-5-(4-hydroxy-3-methoxyphenyl)-
pyrazol-3-yl)-8-(2-(4-hydroxy-3-methoxyphenyl)ethen-1-
yl)-2,4-dimethyl-1,5,6,8a,9-pentaazafluorene (14)
1616 (C N) 1595 (C C), 1570 (N N); H1 NMR (DMSO-d6):
–
–
–
–
–
–
d ppm ¼ 2.89, 3.34 (2s, 6H, 2CH3), 3.85, 3.88 (s, 3H, OCH3), 6.67
Yield 64%; m.p.: 251°C; IR (KBr): n/cmꢀ1 ¼ 3405 (br, 2OH), 1600
–
(br, 2H, 2OH), 6.86–7.94 (m, 11H, Ar–H þ CH CH); MS: m/z
–
1
(%) ¼ 622 (1.5, Mþ), 570 (3.6), 457 (2.1), 425 (1.8), 398 (2.0), 333
(24.5), 291 (29.0), 277 (10.9), 248 (8.6), 214 (4.5), 181 (3.0), 162
(61.3), 142 (40.9), 124 (78.8), 109 (100), 107 (72.3), 81 (92.2), 76
(84.3), 64 (87.8), 52 (47.8). Anal. for C37H30N6O4 (622.67): calcd. C,
71.37; H, 4.86; N, 13.50%. Found: C, 71.53; H, 4.93; N, 13.34.
–
–
–
(C C), 1563 (N N); H NMR (DMSO-d ): d ppm ¼ 2.61, 2.73 (2s, 6H,
–
6
2CH3-pyridine), 3.81, 3.85 (2s, 6H, 2OCH3), 3.88 (dd, J ¼ 12.0, 5 Hz,
1H, pyrazoline), 3.97 (dd, J ¼ 7.8, 5 Hz, 1H, pyrazoline), 4.95 (dd,
J ¼ 7.8, 5Hz, 1H, pyrazoline), 6.75 (br, 2H, 2OH), 6.83–8.23 (m, 14H,
þ
–
–
Ar–H þ CH CH); MS: m/z (%) ¼ 613 (2.2, M ), 575 (2.6), 322 (79.82),
287 (0.7), 259 (0.3), 223 (0.2), 201 (0.3),175 (0.5), 135 (3.5), 109 (9.1),
107 (11.7), 81 (17.5), 77 (71.9), 52 (100). Anal. for C35H31N7O4
(613.67): calcd. C, 68.50; H, 5.09; N, 15.98%. Found: C, 68.64; H,
5.24; N, 15.78.
7-(2-Amino-4-(3-hydroxy-4-methoxyphenyl)-pyrimindin-6-
yl)-8-(2-{(3-hydroxy-4-methoxyphenyl)ethen-1-yl}-2,4-
dimethyl-1,5,6,8a,9-pentaaza-fluorene (18)
A mixture of compound 10 (1 mmol) and guanidine nitrate
(1.3 mmol) in pyridine (10 mL) was refluxed for 15 h, left to cool,
diluted with water, and the obtained solid product was
crystallized from ethanol/DMF to give product 18.
7-(4,5-Dihydro-5-(4-hydroxy-3-methoxyphenyl)isoxazol-3-
yl)-8-(2-(4-hydroxy-3-methoxyphenyl)ethen-1-yl)-2,4-
dimethyl-1,5,6,8a,9-pentaazafluorene (15)
Yield 58%; m.p.: >300°C; IR (KBr): n/cmꢀ1 ¼ 3416 (br, 2OH),
A mixture of compound 10 (1 mmol) and hydroxyl amine
hydrochloride (0.14 and 2 mmol) in pyridine (10 mL) was refluxed
for 12 h, left to cool, diluted with water, and the obtained solid
products were crystallized from ethanol/DMF to give product 15.
3340, 3250 (NH ) 1642 (C N), 1595 (C C), 1553 (N N); 1H NMR
–
–
–
–
–
–
2
(DMSO-d6): d ppm ¼ 2.62, 2.83 (2s, 6H, CH3-pyridine), 3.76, 3.84
(2s, 6H, 2OCH3), 6.78 (br.s, 2H, 2OH), 6.84–7.48 (m, 9H,
Yield 58%; m.p.: 213°C; IR (KBr): n/cmꢀ1 ¼ 3433 (br, 2OH), 1595
–
Ar–H þ CH CH), 8.34 (s, 1H, CH-pyrimidine), 8.66 (br, 2H, NH );
–
2
1
–
–
–
(C C), 1564 (N N); H NMR (DMSO-d ): d ppm ¼ 2.60, 2.84 (2s, 6H,
–
MS: m/z (%) ¼ 562 (1.1, Mþ), 538 (1.1), 518 (1.0), 484 (1.1), 434 (1.1),
331 (1.1),300 (1.1), 252 (1.1), 180 (1.1), 162 (1.1), 147 (1.1), 122 (1.1),
119 (5.3), 89 (1.1), 77 (7.5), 64 (30.9), 52 (100). Anal. for C30H26N8O4
(562.58): calcd. C, 64.05; H, 4.66; N, 19.92%. Found: C, 64.23; H,
4.65; N, 19.78.
6
2CH3-pyridine), 3.74, 3.83 (2s, 6H, 2OCH3), 3.91 (dd, J ¼ 12.0, 5 Hz,
1H, isoxazoline), 3.96 (dd, J ¼ 7.8, 5 Hz, 1H, isoxazoline), 4.76 (dd,
J ¼ 7.8, 5Hz, 1H, isoxazoline), 6.76 (br.s, 2H, 2OH), 6.82–8.48 (m,
–
–
9H, Ar–H þ CH CH); MS: m/z (%) ¼ 524 (3.2, Mꢀ14), 396 (3.6), 378
(3.7), 365 (15.2), 352 (3.5), 322 (3.6), 294 (4.0), 278 (4.6), 247 (5.3),
230 (7.0), 202 (7.4), 165 (15.7), 150 (55.1), 135 (60.6), 109 (83.4), 107
(18.2), 77 (100), 64 (84.3), 52 (60.3). Anal. for C29H26N6O5 (538.55):
calcd. C, 64.68; H, 4.87; N, 15.60%. Found: C, 64.68; H, 4.87; N,
15.60.
7-(2-Mercapto-4-(3-hydroxy-4-methoxyphenyl)-
pyrimindin-6-yl)-8-(2-(3-hydroxy-4-methoxyphenyl)ethen-
1-yl}-2,4-dimethyl-1,5,6,8a,9-pentaazafluorene (19)
A mixture of compound 10 (1 mmol), thiourea (1.5 mmol), and
sodium ethoxide (0.02 mol sodium, in 50 mL ethanol) was
refluxed for 16 h, left to cool, diluted with water, and acidified
with dilute acetic acid. The precipitated solids were filtered and
crystallized from ethanol/DMF to give product 19.
7-(2-Amino-3-cyano-6-(3-hydroxy-4-methoxyphenyl)-
pyridine-4-yl)-8(2-(3-hydroxy-4-methoxyphenyl)ethen-
1-yl)-2,4-dimethyl-1,5,6,8a,9-pentaaza-fluorine (16)
A mixture of 10 (2 mmol), malononitrile (2 mmol), and ammoni-
um acetate (4 mmol) in 20 mL ethanol/acetic acid (1:1) was
refluxed for 12 h. The reaction mixture was allowed to stand
overnight and then basified by dilute ammonium hydroxide. The
Yield 67%; m.p.: >300°C; IR (KBr): n/cmꢀ1 ¼ 3428 (br, 2OH),
1
–
–
–
–
–
1628 (C N), 1594 (C C), 1567 (N N), 1279 (C S); H NMR (DMSO-
–
–
–
d6): d ppm 2.66, 2.77 (2s, 6H, 2CH3-pyridine), 3.79, 3.82 (2s, 6H,
–
2OCH ), 6.72 (br, 2H, 2OH), 6.80–7.50 (m, 9H, Ar–H þ CH CH),
–
3
ß 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

132
M. H. M. Helal et al.
Arch. Pharm. Chem. Life Sci. 2014, 347, 123–133
8.24 (s, 1H, CH-pyrimidine), 9.56 (br, 1H, NH); MS: m/z (%) ¼ 579
(2.7, Mþ), 475 (2.2), 431 (1.3), 353 (1.3), 298 (1.3), 268 (1.3), 189
(1.3), 173 (1.6), 149 (4.8), 124 (10.2), 109 (25.0), 94 (11.0), 77
(30.6), 69 (51.1), 57 (100). Anal. for C30H25N7O4S (579.63):
calcd. C, 62.16; H, 4.35; N, 16.92%. Found: C, 61.43; H, 4.45; N,
16.577.
Reaction of curcumin with 5-chloro-3-methyl-1-phenyl-1H-
pyrazole-4-carbaldehyde pyrazole (24)
A suspension of curcumin1 (5 mmol), 24 (5 mmol), and ammoni-
um acetate (11 mmol), piperidine (10 mmol), or morpholine
(10 mmol) in ethanol (30 mL) was refluxed for 18 h, left to cool,
diluted with water, and the obtained solid products were
crystallized from ethanol/DMF to give products 25–27.
3,3-Bis(7-(4-hydroxy-3-methoxyphenyl)-1-(4-hydroxy-3-
methoxyphenyl)-3,5-dioxo-hepta-1,6-dien-4-yl)indolin-
2-ones (21–23)
A mixture of compound 1 (2 mmol), isatin 20a–c (1 mmol) in
ethanol (30 mL) containing piperidine (0.2 mL) was refluxed
for 12 h, left to cool, diluted with water, and the obtained
solid products were crystallized from ethanol/DMF to give
21–23.
1-(6-(4-Hydroxy-3-methoxystyryl)-3-methyl-1-phenyl-1H-
pyrazolo[3,4-b]pyrid-in-5-yl)-3-(4-hydroxy-3-
methoxyphenyl)prop-2-en-1-one (25)
Yield 58%; m.p.: 228°C; IR (KBr): n/cmꢀ1 ¼ 3357 (br, 2OH), 1658
1
–
–
–
–
(C O), 1605 (C N), 1595 (C C); H NMR (DMSO-d ): d ppm ¼ 2.60
–
–
6
(s, 3H, CH3) 3.78, 3.83 (s, 3H, OCH3), 6.56 (br, 2H, 2OH), 6.73–7.50
–
(m, 16H, Ar–H þ 2CH CH); MS: m/z (%) ¼ 518 (0.1, M-CH ), 468
–
3
(0.9), 438 (1.1), 414 (1.0), 400 (3.8), 381 (1.3), 348 (1.8), 331 (1.0), 308
(9.0), 278 (1.8), 250 (1.1), 216 (2.0), 185 (7.7), 174 (25.6), 137 (12.6),
124 (23.0), 109 (27.6), 105 (21.5), 91 (46.0), 89 (5.9), 77 (100), 64
(30.4). Anal. for C32H27N3O5 (533.57): calcd. C, 72.03; H, 5.10; N,
7.88%. Found: C, 72.23; H, 5.24; N, 7.65.
3,3-Bis(7-(4-hydroxy-3-methoxyphenyl)-1-(4-hydroxy-3-
methoxyphenyl)-3,5-dioxohepta-1,6-dien-4-yl)indolin-
2-one (21)
Yield 68%; m.p.: 229°C; IR (KBr): n/cmꢀ1 ¼ 3422 (br, 2OH), 3330
(NH), 1704 (C O-indole), 1655 (br, 4C O), 1594 (C C); 1H NMR
–
–
–
–
–
–
1,7-Bis-(4-hydroxy-3-methoxyphenyl)-4-((3-methyl-1-
phenyl-5-(piperidin-1-yl)-1H-pyrazol-4-yl)methylene)-
(DMSO-d6): d ppm ¼ 3.76, 3.80 (2s, 12H, 4OCH3), 6.57–8.25 (m, 28H,
–
Ar–H þ 4CH CH þ 4OH), 9.50 (br.s, 2H, OH enolic), 9.64 (br.s, 1H,
–
NH-indole); MS: m/z (%) ¼ 865 (0.1, Mþ), 664 (0.1), 624 (0.2), 555
(0.5), 485 (4.8), 435 (6.8), 408 (5.0), 368 (11.3), 350 (46.5), 323 (18.0),
261 (27.4), 231 (14.5), 217 (18.6), 177 (94.8), 145 (100), 150 (81.6),
135 (63.6), 117 (55.5), 107 (50.4), 89 (89.8), 77 (53.3), 55 (39.2). Anal.
for C50H43NO13: calcd. C, 69.36; H, 5.01; N, 1.62%. Found: C, 69.53;
H, 5.23; N, 1.81.
hepta-1,6-diene-3,5-dione (26)
Yield 58%; m.p.: 225°C; IR (KBr): n/cmꢀ1 ¼ 3412 (br, 2OH), 1659
(br, 2C O), 1612 (C N), 1596 (C C); 1H NMR (DMSO-d6):
–
–
–
–
–
–
d ppm ¼ 1.87 (m, 6H, 3 CH2-piperidine), 2.46 (s, 3H, CH3), 2.98
(m, 4H, 2CH2), 3.76, 3.95 (2s, 6H, 2OCH3), 6.61 (br, 2H, 2OH), 7.05–
–
–
–
8.34 (m, 16H, Ar–H þ 2CH CH þ CH ); MS: m/z (%) ¼ 618 (0.7,
–
Mꢀ2), 435 (0.7), 386 (0.7), 355 (0.8), 326 (0.8), 308 (1.4), 277 (0.8),
259 (0.8), 225 (1.4), 206 (0.9), 174 (3.2), 145 (1.8), 124 (2.5), 104 (3.3),
84 (7.9), 77 (14.7), 64 (2.8). Anal. for C37H37N3O6 (619.71): calcd. C,
71.71; H, 6.02; N, 6.78%. Found: C, 71.92; H, 6.32; N, 6.54.
3,3-Bis(7-(4-hydroxy-3-methoxyphenyl)-1-(4-hydroxy-3-
methoxyphenyl)-3,5-dioxohepta-1,6-dien-4-yl)-5-
methylindolin-2-one (22)
Yield 75%; m.p.: 225°C; IR (KBr): n/cmꢀ1 ¼ 3410 (br,4OH), 3355
(NH), 1694 (C O-indole), 1662 (br, 4C O), 1594 (C C); 1H NMR
1,7-Bis-(4-hydroxy-3-methoxyphenyl)-4-((3-methyl-5-
morpholino-1-phenyl-1H-pyrazol-4-yl)methylene)hepta-
–
–
–
–
–
–
(DMSO-d6): d ppm ¼ 2.47 (s, 3H, CH3), 3.77, 3.80 (2s, 12H, 4 OCH3),
–
6.56–8.1 (m, 26H, Ar–H þ CH CH þ 4OH), 8.80 (br.s, 2H, 2OH-
–
1,6-diene-3,5-dione (27)
enolic), 9.95 (br, H, NH-indole); MS: m/z (%) ¼ 879 (0.7, Mþ), 486
(1.1), 432 (0.9), 402 (0.7), 377 (0.9), 349 (0.6), 322 (1.8), 295 (1.6), 261
(1.3), 228 (3.2), 190 (3.2), 177 (12.9), 150 (26.1), 134 (34.2), 119
(10.4), 107 (16.1), 84 (20.7),77 (31.9), 43 (100). Anal. for C51H45NO13
(879.9): calcd. C, 69.62; H, 5.15; N, 1.59%. Found: C, 69.62; H, 5.24;
N, 1.64.
Yield 58%; m.p.: 196°C; IR (KBr): n/cmꢀ1 ¼ 3413 (br, 2OH), 1651
(br, 2C O), 1607 (C N), 1596 (C C); 1H NMR (DMSO-d6):
–
–
–
–
–
–
d ppm ¼ 1.51–1.72 (m, 6H, 3CH2) 2.55 (s, 3H, CH3) 2.85–2.87
(t, 4H, 2CH2), 3.65–2.77 (t, 4H, 2CH2), 3.80, 3.83 (2s, 6H, 2OCH3),
–
6.56 (br, 2H, 2OH), 6.89–7.87 (m, 16H, Ar–H þ 2CH CH þCH); MS:
–
m/z (%) ¼ 621 (0.7, Mþ), 547 (0.7), 451 (0.7), 432 (0.8), 364 (0.8), 335
(1.4), 304 (0.8), 271 (0.8), 235 (1.4), 219 (0.9), 200 (3.2), 177 (1.8), 150
(2.5), 131 (3.3), 105 (1.5), 86 (3.1), 77 (100), 52 (7.5). Anal. for
C36H35N3O7 (621.68): calcd. C, 69.55; H, 5.67; N, 6.76%. Found: C,
69.65; H, 5.49; N, 6.81.
5-Chloro-3,3-bis(7-(4-hydroxy-3-methoxyphenyl)-1-
(4-hydroxy-3-methoxyphenyl)-3,5-dioxohepta-1,6-
dien-4-yl)indolin-2-one (23)
Yield 81%; m.p.: 184°C; IR (KBr): n/cmꢀ1 ¼ 3421 (br, 2OH), 3360
The authors have declared no conflict of interest.
(NH), 1708 (C O-indole), 1654 (br, 4C O), 1595 (C C); 1H NMR
–
–
–
–
–
–
(DMSO-d6): d ppm ¼ 3.72, 3.81 (2s, 12H, 4OCH3), 6.57–8.25 (m, 27H,
–
Ar–H þ 4CH CH þ 4OH), 8.50 (br.s, 2H, OH enolic), 8.95 (br.s, 1H,
–
NH-indole); MS: m/z (%) ¼ 901 (Mþþ1, 6.32), 899 (18.5, Mþꢀ1),
538 (17.2), 523 (34.8), 476 (22.4), 430 (17.7), 407 (21.6), 391
(34.8), 366 (21.8), 355 (30.6), 308 (21.2), 287 (35.2), 270 (96.4), 235
(100), 233 (28.4), 217 (27.3), 187 (42.7), 177 (36.3), 150 (42.3),
137 (44.3), 110 (20.2), 94 (35.9), 82 (58.7), 77 (77.3), 68 (80.9), 54
(88.7). Anal. for C50H42ClNO13 (900.32): calcd. C, 66.70; H, 4.70; N,
1.56%. Found C, 66.82; H, 4.57; N, 1.43.
References
[1] S. M. Bayomi, H. A. El-kashef, M. B. El-Ashmawy, M. N. A. Nasr,
M. A. El-Sherbeny, F. A. Baderia, L. A. Abou-Zeid, M. A. Ghaly,
N. I. Abdel-Aziz, Med. Chem. Res. 2013, 22 (3), 4035–4041.
[2] E. O. Farombi, S. Shrotriya, H. N. Kim, Y. Surh, Food Chem.
Toxicol. 2008, 46, 1279–1287.
ß 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

Arch. Pharm. Chem. Life Sci. 2014, 347, 123–133
Antioxidant Activity of Novel Curcumins
133
[3] B. Joe, M. Vijaykumar, B. R. Lokesh, Crit. Rev. Food Sci. Nutr.
2004, 44, 97–111.
[26] M. M. F. Ismail, K. M. Amin, E. Noaman, D. H. Soliman,
Y. A. Ammar, Eur. J. Med. Chem. 2010, 45, 2733–2738.
[4] C. C. Araujo, L. L. Leon, Mem. Inst. Oswaldo Cruz 2001, 96, 723–
[27] A. A. Farag, E. M. Khalifa, N. A. Sadik, S. Y. Abbas, A. G. Al-
728.
Sehemi, Y. A. Ammar, Med. Chem. Res. 2013, 22, 440–452.
[5] N. Chainani-Wu, J. Altern. Complement Med. 2003, 9, 161–168.
[28] Y. A. Ammar, M. M. F. Ismail, H. M. El-Sehrawi, E. Noaman,
A. H. Bayomi, T. Z. Shawer, Arch. Pharm. Chem. Life Sci. 2006,
339, 429–436.
[6] Y. J. Surh, K. S. Chun, H. H. Cha, S. S. Han, Y. S. Keum,
K. K. Park, S. S. Lee, Mutat. Res. 2001, 1, 243–268.
[29] P. J. Daris, J. M. Muchowski, J. Heterocyclic Chem. 1975, 12, 761–
[7] A. A. Nanji, K. Jokelainen, G. L. Tipoe, A. Rahemtulla,
P. Thomas, A. J. Dannenberg, Am. J. Physiol. Gastrointest. Liver
Physiol. 2003, 284, G321–G327.
762.
[30] A. E. Gilman, E. S. Stern, An Introduction to Electronic Absorption
Spectroscopy, 2nd edn., Edward Arnold Publisher Ltd, London
1957, p. 302.
[8] R. Rukkumani, K. Aruna, P. S. Varma, K. N. Rajasekaran,
V. P. Menon, J. Pharm. Pharm. Sci. 2004, 7, 274–283.
[31] A. E. Gilman, E. S. Stern, An Introduction to Electronic Absorption
Spectroscopy in Organic Chemistry, 2nd edn., Edward Arnold,
London 1960, p. 871.
[9] K. Okada, C. Wangpoengtrakul, T. Tanaka, S. Toyokuni,
K. Uchida, T. Osawa, J. Nutr. 2001, 131, 2090–2095.
[10] Y. Jiang, Z. Du, G. Xue, Q. Chen, Y. Lu, X. Zheng, A. H. Conney,
[32] A. Ahmed, A. F. Fadda, B. M. Kh. El-Attar, Med. Chem. Res. 2010,
19, 413–430.
K. Zhang, Molecules 2013, 18, 3948–3961.
[11] J. S. Wright, J. Mol. Struct. (Theochem) 2002, 591, 207–217.
[33] T. Fenner, C. H. Schiesser, Molecules 2004, 9, 472–479.
[12] L. R. C. Barclay, M. R. Vinqvist, K. Mukai, H. Goto, Y. Hashimoto,
[34] A. C. Bustamante, J. M. V. Paredes, A. F. Parra, A. L. Campos,
F. J. M. Martínez, M. T. S. Martínez, Á. R. Organillo, Molecules
2010, 15, 5445–5459.
A. Tokunaga, H. Uno, Org. Lett. 2000, 2 (18), 2841–2843.
[13] P. Venkatesan, M. N. A. Rao, J. Pharm. Pharmacol. 2000, 52 (9),
1123–1128.
[35] W. Malinka, M. Kaczmarz, B. Filipek, J. Sapa, B. Glod, Il
Farmaco 2002, 57 (9), 737–746.
[14] S. Wang, B. Chen, C. Sun, Weisheng Yanjiu 2000, 29 (4), 240–
242.
[36] A. B. A. El-Gazzar, M. M. Youssef, A. M. S. Youssef, A. A. Abu-
[15] M. Toshiya, M. Tomomi, H. Kayo, B. Hiromi, T. Yoshio,
Hashem, F. A. Badria, Eur. J. Med. Chem. 2009, 44, 609–624.
Y. Hidemasa, J. Agric. Food Chem. 2001, 49 (5), 2254–2539.
[37] A. A. Abu-Hashem, M. M. Youssef, H. A. R. Hussein, J. Chin.
Chem. Soc. 2011, 58, 1–8.
[16] N. Sreejayan, M. N. A. Rao, J. Pharm. Pharmacol. 1994, 46, 1013–
1016.
[38] P. Anand, S. G. Thomas, A. B. Kunnumakkara, C. Stundaram,
K. B. Harikumar, B. Sung, Biochem. Pharmacol. 2008, 76, 1590–
1611.
[17] S. A. Awadallab, H. I. El-Subbagha, Arch. Pharm. Chem. Life Sci.
2005, 338, 175–180.
[18] S. Sang, C. H. Liao, M. H. Pan, R. T. Rosen, S. L. Shiau, J. K. Lin,
[39] S. V. Jovanovic, S. Steenken, C. W. Boone, M. G. Simic, J. Am.
Chem. Soc. 1999, 121, 9677–9968.
C. T. Ho, Tetrahedron 2002, 58, 10095–10102.
[19] W. B. Pratt, R. W. Ruddon, W. D. Ensminger, J. Maybaun, The
Anticancer Drugs, 2nd Edn., Oxford University Press, New
York, NY 1994, pp. 313–332.
[40] L. R. C. Barclay, M. R. Vinqvist, K. Mukai, H. Goto, Y. Hashimoto,
A. Tokuanga, H. Uno, Org. Lett. 2000, 2, 2841–2843.
[41] Y. M. Sun, H. Y. Zhang, D. Z. Chen, C. B. Liu, Org. Lett. 2002, 4,
2909–2911.
[20] K. M. Youssef, M. A. El-Sherbeny, F. A. El-Shafie, H. A. Farag,
O. A. Al-Deeb, S. A. Awadalla, Arch. Pharm. Pharm. Med. Chem.
2004, 337, 42–54.
[42] L. Shen, H. Y. Zhang, H. F. Ji, Org. Lett. 2005, 7, 243–246.
[43] K. I. Priyadarsini, D. K. Maity, G. H. Naik, M. S. Kumar,
M. K. Unnikrishnan, J. G. Satav, H. Mohan, Biol. Med. 2003, 35,
475–484.
[21] H. I. El-Subbagh, S. M. Abu-Zaid, M. A. Mahran, F. A. Badria,
A. M. Al-Obaid, J. Med. Chem. 2000, 43, 2915–2921.
[22] A. S. Al-Tuwaijri, I. A. Al-Mofleh, A. A. Mahmoud, J. Med.
Microbiol. 1990, 32, 189–193.
[44] C. Selvam, S. M. Jachak, R. Thilagavathi, A. K. Chakraborti,
Bioorg. Med. Chem. 2005, 15, 1793–1797.
[23] A. S. Al-Tuwaijri, A. A. Mustafa, Int. J. Immunopharmacol. 1992,
14, 83–91.
[45] M. I. de Heer, P. Mulder, H. G. Korth, K. U. Ingold, J. J. Lusztyk,
Am. Chem. Soc. 2000, 122, 2355–2360.
[24] M. H. M. Helal, M. A. Salem, M. S. A. El-Gaby, M. Aljahdali,
[46] M. Aljahdali, A. A. El-Sherif, Inorg. Chim. Acta, 2013, 407, 58–68.
Eur. J. Med. Chem. 2013, 65, 517–526.
[47] M. Aljahdali, A. A. El-Sherif, R. Hilal, Eur. J. Chem. 2013, 4 (4),
370–378.
[25] E. A. Lissi, B. Modak, R. Torres, J. Escobar, A. Urzua, Free
Radical Res. 1999, 30 (6), 471–477.
ß 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com