10H-Phenothiazines: A new class of enzyme inhibitors for inflammatory diseases

Article abstract of DOI:10.1016/j.ejmech.2008.02.028

The phenothiazine nucleus is known for their inhibitory activity towards the regulatory enzymes that are contributing to diseases such as asthma, autoimmune diseases including allergic rheumatoid and encephalomyelitis. In this study a number of substitute

Full text of DOI:10.1016/j.ejmech.2008.02.028

Available online at www.sciencedirect.com
European Journal of Medicinal Chemistry 44 (2009) 197e202
http://www.elsevier.com/locate/ejmech
Original article
10H-Phenothiazines: A new class of enzyme inhibitors
for inflammatory diseases
*
Y.S. Sadanandam, Meera M. Shetty, A. Bhaskar Rao , Y. Rambabu
Organic Chemistry Division, Indian Institute of Chemical Technology, Taranaka, Hyderabad 500 007, Andhra Pradesh, India
Received 28 May 2007; received in revised form 28 January 2008; accepted 8 February 2008
Available online 7 March 2008
Abstract
The phenothiazine nucleus is known for their inhibitory activity towards the regulatory enzymes that are contributing to diseases such as
asthma, autoimmune diseases including allergic rheumatoid and encephalomyelitis. In this study a number of substituted phenothiazines
were synthesized and screened for their biological activity against the regulatory enzymes involved in inflammatory diseases. Our results
show that the newly synthesized compounds 4aec and 5aec exhibited promising target specific enzyme inhibition against phosphodiesterase,
prostaglandin dehydrogenase and superoxide dismutase activity depending on steric factors of the molecules.
Ó 2008 Elsevier Masson SAS. All rights reserved.
Keywords: Enzyme inhibition; Phenothiazine; Prostaglandin synthetase; Target specific
1. Introduction
[10e12]. Due to the increased importance of these heterocy-
clic compounds, attempts were made during the past few years
in the synthesis of new generation of 10H-phenothiazines that
exert their biological activity through modulation [13e15].
The wide range of biological activities exhibited by these phe-
nothiazine analogues inspired us to prepare several 10H- and
2,10-dihydro-1H-phenothiazine derivatives and to evaluate
them for selective enzyme inhibition studies.
The pathophysiological functions of acute and chronic
inflammatory diseases such as asthma, arthritis, autoimmuno
disorders are due to production of a variety of chemical medi-
ators such as leukotrienes, cytokines and prostaglandins
released from biosynthetic cascade of arachidonic acid cata-
lyzed via phospholipase A2 (PLA2), lipoxygenase and cyclo-
xygenase enzymes [1e3]. These regulatory enzymes are
believed to play an important role in initiating and amplifying
the inflammatory disorders in the body, contributing to dis-
eases such as asthma (bronco contraction), autoimmune disor-
ders, etc. [4e6]. Phenothiazines form an important class of
heterocyclic compounds possessing wide spectrum diverse
biological activities like antitumor, antimalarial, antipsychotic,
anti-inflammatory, etc. [7e9]. The phenothiazines contain an
interesting heterocyclic ring skeleton with two carbocyclic/
aromatic rings connected to each other via a sulfide and an
imino bridge which facilitates several types of reactions, sub-
stitution at the nitrogen, electrophilic substitution on the aro-
matic rings, N-oxidation and photochemical reactions, etc.
2. Results and discussion
2.1. Chemistry
For the synthesis of title compounds, the key intermediates
4-hydroxy-N,N0,4-trimethyl-6-oxo-2-phenylcyclohexane-1,3-
dicarboxamide (2a), 4-hydroxy-2-(2-methylphenyl)-N,N0,4-tri-
methyl-6-oxocyclohexane-1,3-dicarboxamide (2b), 2-(2-chlor-
ophenyl)-4-hydroxy-N,N0,4-trimethyl-6-oxocyclohexane-1,
3-dicarboxamide (2c), 2-(4-chlorophenyl)-4-hydroxy-N,N0,4-
trimethyl-6-oxocyclohexane-1,3-dicarboxamide (2d), 4-hydroxy-
2-(2-methoxyphenyl)-N,N0,4-trimethyl-6-oxocyclohexane-1,
3-dicarboxamide (2e), 4-hydroxy-2-(4-methoxyphenyl)-N,N0,
4-trimethyl-6-oxocyclohexane-1,3-dicarboxamide (2f), 2-(1,3-
benzodioxol-5-yl)-4-hydroxy-N,N0,4-trimethyl-6-oxocyclohexane-1,
* Corresponding author. Tel.: þ91 040 27193374; fax: þ91 040 27160512.
E-mail address: adarirao2002@yahoo.co.in (A.B. Rao).
0223-5234/$ - see front matter Ó 2008 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2008.02.028

198
Y.S. Sadanandam et al. / European Journal of Medicinal Chemistry 44 (2009) 197e202
3-dicarboxamide (2g) and 4-hydroxy-2-(4-nitrophenyl)-N,
N0,4-trimethyl-6-oxocyclohexane-1,3-dicarboxamide (2h)
were prepared by stirring an ethanol solution of N-methyl-3-
oxobutanamide with the corresponding aromatic aldehyde in
the presence of catalytic amount of piperidine at room temper-
ature in 52e66% yield. The reaction of 2-aminothiophenol (1)
with 4-hydroxy-N,N0,4-trimethyl-6-oxo-2-arylcyclohexane-1,
3-dicarboxamides (2aeh) in the presence of p-toluenesulfonic
acid in dry toluene gave the corresponding enamines, 2-phenyl-
N,N0,4-trimethyl-6-[(2-sulfanyl)amino]cyclohexa-3,5-diene-1,
3-dicarboxamide (3a), 2-(2-methylphenyl)-N,N0,4-trimethyl-6-
[(2-sulfanyl)amino]cyclohexa-3,5-diene-1,3-dicarboxamide (3b),
2-(2-chlorophenyl)-N,N0,4-trimethyl-6-[(2-sulfanyl)amino]cyclo-
hexa-3,5-diene-1,3-dicarboxamide (3c), 2-(4-chlorophenyl)-N,
N0,4-trimethyl-6-[(2-sulfanyl)amino]cyclohexa-3,5-diene-1,3-
dicarboxamide (3d), 2-(2-methoxyphenyl)-N,N0,4-trimethyl-6-
[(2-sulfanyl)amino]cyclohexa-3,5-diene-1,3-dicarboxamide (3e),
2-(4-methoxyphenyl)-N,N0,4-trimethyl-6-[(2-sulfanyl)amino]-
cyclohexa-3,5-diene-1,3-dicarboxamide (3f), 2-(1,3-benzo-
dioxol-5-yl)-N,N0,4-trimethyl-6-[(2-sulfanyl)amino]cyclohexa-3,
5-diene-1,3-dicarboxamide (3g) and 2-(4-nitrophenyl)-N,N0,4-
trimethyl-6-[(2-sulfanyl)amino]cyclohexa-3,5-diene-1,3-dicar-
boxamide (3h) (Scheme 1). The physical data of these enamines
3aeh are given in Table 1. 2-Aryl-N,N0,4-trimethyl-6-[(2-sul-
fanyl)amino]cyclohexa-3,5-diene-1,3-dicarboxamides 3aeh on
heating in dimethyl sulfoxide gave a mixture of the corre-
sponding 2-aryl-N,N0,4-trimethyl-2,10-dihydro-1H-phenothia-
zine-1,3-dicarboxamides (4aeh) and 2-aryl-N,N0,4-trimethyl-
O
H
OH
H
H3C
H
CHO
N
R1
CH3
R1
R2
R2
H
Piperidine
O
H3C
N
+
H
N
CH3
R3
O
O
O
R3
H
CH3
O
H
OH
H3C
O
CH3
H
H
N
SH
H
SH
R1
CH3
R2
DMSO
pTS
Toluene
N
R1
CH3
H
+
O
R2
130-140 °C
H
N
N
H
NH2
R3
H
N
O
O
R3
H
CH3
H
CH3
1
2a-h
3a-h
H
N
S
S
O
CH3
H
N
R1
CH3
H
..
N
H
R2
H
N
O
R3
H
CH3
O
CH3
O
CH3
5
H
S
6
9
4
H
S
N
3
R1
N
7
8
CH3
R2
R1
CH3
H
2
10
+
R2
N
H
1
N
H
H
N
O
R3
N
O
R3
H
CH3
CH3
H
4 a-h
5 a-h
(a) R1 = R2 = R3 = H
(d) R1 = H, R2 = R3 = Cl
(g) R1 = H, R2 = R3 = -O-CH2-O-
(h) R1 = R2 = H, R3 = NO2
(b) R1 = CH3R2 = R3 = H
(c) R1 = Cl, R2 = R3 = H
(e) R1 = OCH3, R2 = R3 = H
(f) R1 = R2 =H, R3 = OCH3
Scheme 1. Synthesis of substituted 1H-2,10-dihydro- and 10H-phenothiazines.

Y.S. Sadanandam et al. / European Journal of Medicinal Chemistry 44 (2009) 197e202
199
Table 1
Physical data of 2-aryl-N,N0,4-trimethyl-6-[(2-sulfanylphenyl)amino]cyclo-
hexa-3,5-diene-1,3-dicarboxamides (3aeh)
diseases such as asthma and chronic inflammatory disease.
In principal the pharmacological activity of anti-inflammatory
compounds is by inhibition of the enzymes that participate in
arachidonic acid metabolism. Phenothiazines are important
heterocyclic systems that have wide range of biological
activities.
Compound M.p. (ꢁC) Yield IR (KBr) (cmꢀ1
(%)
)
3a
3b
3c
3d
3e
3f
244e246
245e247
225e227
247e249
246e248
240e242
248e250
257e259
64
60
50
64
56
65
61
59
3280 (NH), 2920 (CH3), 1640, 1610
(CONH), 1550 (C]C)
From the results summarized in Tables 2 and 3, it is appar-
ent that all the derivatives of 2,10-dihydro-1H-phenothiazine
(4aeh) and 10H-phenothiazine compounds (5aeh) exhibit
broad inhibitory activity towards regulating enzymes amplify-
ing the inflammatory disorders. The compounds, 2-phenyl-N,N0,
4-trimethyl-2,10-dihydro-1H-phenothiazine-1,3-dicarboxamide
(4a), 2-(2-methylphenyl)-N,N0,4-trimethyl-2,10-dihydro-1H-
phenothiazine-1,3-dicarboxamide (4b) and 2-(2-chlorophenyl)-N,
N0,4-trimethyl-2,10-dihydro-1H-phenothiazine-1,3-dicarboxa-
mide (4c), exhibited promising phosphodiesterase, prostaglandin
synthetase and superoxide dismutase inhibition activity, when
compared to standard drug aspirin. Within the 10H-phenothi-
azine derivatives 5aeh studied the compounds 2-phenyl (5a),
2-(2-methyl-phenyl) (5b) and 2-(2-chlorophenyl) (5c) have
shown better enzyme inhibitory activity due to hydrophilic na-
ture of the compounds. Whereas compounds 4deh and 5deh
have shown reduced enzyme inhibitory activity which may be
due to increased lipophilicity of the molecule. It appears that
substitution at C1- and C2-positions of the 10H-phenothia-
zines and presence of a 2-phenyl ring without substituents in
meta- and para-positions were important structural require-
ments for exhibiting better chemomodulatory action in inflam-
matory disorders. Enzyme specificity and inhibitory potency
of the phenothiazine derivatives studied can be related to mo-
lecular volumes, steric and electronic factors.
3280 (NH), 3060 (CH3), 1640, 1610
(CONH), 1550 (C]C)
3295 (NH), 3080 (CH3), 1650, 1615
(CONH), 1550 (C]C), 1080 (CeCl)
3290 (NH), 2940 (CH3), 1640, 1620
(CONH), 1580 (C]C), 1085 (CeCl)
3290 (NH), 2960 (CH3), 1650, 1610
(CONH), 1550 (C]C)
3290 (NH), 2960 (CH3), 1650, 1620
(CONH), 1590 (C]C), 1250 (CeOeC)
3280 (NH), 2905 (CH3), 1640, 1610
(CONH), 1550 (C]C), 1038 (OeCeO)
3285 (NH), 2960 (CH3), 1650, 1620
(CONH), 1525, 1345 (NO2)
3g
3h
10H-phenothiazine-1,3-dicarboxamides (5aeh) (Scheme 1)
[16]. The reaction is believed to proceed via the disulfide interme-
diate in which the disulfur bond (SeS) is cleaved by the intramo-
lecularnucleophilicattackoftheenaminesystempresentin3aeh
leadingtotheformationof2-aryl-N,N0,4-trimethyl-2,10-dihydro-
1
1H-phenothiazine-1,3-dicarboxamides (4aeh). The H NMR
spectra of the representative compound 4f exhibited a singlet at
d 1.87 ppm assignable to methyl protons on C4 and two doublets
integratingfor1Heachatd3.15and4.12 ppm(J ¼ 4.8 Hz)attrib-
utable to protons on C1 and C2, respectively. The CONH protons
exchangeable with deuterium were observed at d 5.60 and
6.02 ppm. The IR (KBr) spectra of the compounds 4aeh showed
NH stretching around 3330 cmꢀ1 and the amide carbonyl stretch
1
at 1650 and 1620 cmꢀ1. The H NMR spectra of 2-aryl-N,N0,
4-trimethyl-10H-phenothiazine-1,3-dicarboxamides 5aeh re-
vealed the absence of methine proton signals for C1 and C2 and
downfield shift of C4eCH3 signal to d 2.3 ppm, conforming the
ring aromatization.
3. Conclusion
In vitro studies on enzyme inhibitory activities of newly
synthesized analogues 2,10-dihydro-1H-phenothiazine (4ae
c) and 2-aryl-10H-phenothiazine derivatives (5aec)
exhibited promising in vitro enzyme inhibitory activity and
further structural variation of these compounds could result
in designing a potent lead molecules in the therapy of many
inflammatory diseases.
2.2. Biological activities
It is well known that the prostaglandins and leukotrienes
are important mediators/regulators of chemomodulatory
Table 2
Physical and biological activity data of 2-aryl-N,N0,4-trimethyl-2,10-dihydro-1H-phenothiazine-1,3-dicarboxamides (4aeh)
Compound
M.p.
Yield
Mol. formula
Found (calculated) (%)
IC50 (mM)
C
H
N
PE
PS
GT
20
SOD
4a
4b
4c
4d
4c
4f
244e246
246e248
224e226
258e260
226e227
236e238
158e160
224e226
55
56
46
58
31
32
36
48
C24H23N3O2S
C25H25N3O2S
C23H22ClN3O2S
C23H22ClN3O2S
C24H25N3O3S
C24H25N3O3S
C24H23N3O4S
C23H22N4O4S
68.1 (68.1)
68.8 (68.7)
63.1 (62.9)
61.3 (61.3)
66.2 (66.2)
64.5 (64.5)
64.1 (64.1)
63.5 (63.4)
5.8 (5.7)
6.1 (6.0)
5.1 (5.0)
5.1 (4.9)
5.8 (5.8)
5.8 (5.9)
5.2 (5.2)
5.6 (5.4)
10.4 (10.4)
10.2 (10.0)
9.5 (9.6)
16
18
18
21
16
28
20
20
28
28
15
17
22
19
13
26
18
31
9.5 (12.4)
9.7 (9.7)
9.0 (9.0)
>35
>30
25
>30
21
>30
18
4g
4h
9.3 (9.4)
10.6 (10.5)
>30
>30
>30
36
>30
32
Enzyme inhibition activity: (a) phosphodiesterase activity (PE), (b) prostaglandin synthetase activity (PS), (c) g-glutamyltranspeptidase activity (GT), (d) super-
oxide dismutase (SOD). IC50 e concentration of the substrate where fifty percent (50%) of the enzyme activity was inhibited. Values represent average of three
independent experiments and IC50 values more than 20 mM of substrate concentration were significantly different with respect to that of the control P < 0.01; n ¼3.

200
Y.S. Sadanandam et al. / European Journal of Medicinal Chemistry 44 (2009) 197e202
Table 3
Physical and biological activity data of 2-aryl-N,N0,4-trimethyl-10H-phenothiazine-1,3-dicarboxamides (5aeh)
Compound
M.p.
Yield
Mol. formula
Found (calculated) (%)
IC50 (mM)
C
H
N
PE
PS
GT
SOD
5a
5b
253e255
258e260
321e323
345e347
318e320
267e269
265e267
260e262
16
15
10
15
15
15
10
12
C23H21N3O2S
C24H23N2O2S
C23H20ClN3O2S
C23H20ClN3O2S
C24H23N3O3S
C24H23N3O3S
C21H21N3O4S
C23H20N4O4S
63.2 (63.1)
69.1 (69.1)
63.2 (63.2)
61.1 (61.6)
66.5 (66.5)
64.8 (64.8)
64.4 (64.4)
62.3 (61.9)
4.8 (4.8)
5.5 (5.6)
4.6 (4.6)
4.5 (4.5)
5.3 (5.4)
5.5 (5.4)
4.8 (4.7)
4.5 (4.3)
10.0 (10.1)
10.1 (10.1)
9.6 (9.6)
20
18
15
18
25
22
20
22
22
18
21
15
23
22
18
24
26
24
20
25
18
20
28
21
18
22
36
14
18
5c
5d
20
18
12.4 (12.5)
9.8 (9.7)
9.1 (9.1)
5e
>30
19
5f
5g
9.4 (9.4)
10.3 (10.2)
20
5h
Acetyl salicylic acid (aspirin)
>30
28
Enzyme inhibition activity: (a) phosphodiesterase activity (PE) (b) prostaglandin synthetase activity (PS) (c) g-glutamyltranspeptidase activity (GT) (d) superoxide
dismutase (SOD). IC50 e concentration of the substrate where fifty percent (50%) of the enzyme activity was inhibited. Values represent average of the three
independent experiments and IC50 values more than 20 mM of substrate concentration were significantly different with respect to that of the control P < 0.01;
n ¼ 3.
4. Experimental details
4.3. Evaluation of inhibition activity against enzymes
Melting points were determined on a Buchi capillary melt-
ing point apparatus and are uncorrected. IR spectra were
recorded on a PerkineElmer 283B spectrophotometer in a po-
tassium bromide pellet. The NMR spectra were recorded on
a Jeol FX 200 FT NMR spectrometer using tetramethylsilane
as internal standard. Mass spectra were recorded on a VG-70
70H micromass spectrometer. Product purification was carried
out by column chromatography using Acme silica gel (100e
200 mesh). Elemental analyses were carried out on a Per-
kineElmer 240 B analyzer.
The different concentrations of 4aeh and 5aeh com-
pounds were used to study IC50 values against enzymes known
for their role in many inflammatory diseases i.e., phosphodies-
terase, prostaglandin dehydrogenase, g-glutamyltranspepti-
dase and superoxide dismutase. The phosphodiesterase
inhibition activity was determined by measuring the produc-
tion of inorganic phosphate in the presence of an excess of
50-nucleotidase [17]. Arachidonic acid metabolites (prosta-
glandin E and leukotrienes) were analyzed by HPLC using
reverse phase ODS-18 column with acetonitrile:water
(70:30) as mobile phase and absorbance monitored at
280 nm using isolated soya bean lipooxygenase as a source
of enzyme [18]. g-Glutamyltranspeptidase inhibition was
measured by standard procedure colorimetrically at 405 nm
[19]. Superoxide dismutase (SOD) activity was measured by
inhibition of superoxide generation (Oꢀ2 ) in cell membrane
free system spectrophotometrically at 340 nm [20].
4.1. Synthesis of 2-aryl-N,N0,4-trimethyl-6-
[(2-sulfanylphenyl)amino]cyclohexa-3,
5-diene-1,3-dicarboxamide (3aeh)
A mixture of 2-aminothiophenol (1) (0.03 mol), 2-aryl-4-hy-
droxy-N,N0,4-trimethyl-6-oxocyclohexane-1,3-dicarboxamide
(2aeh) (0.03 mol), dry toluene (150 ml) and catalytic amount
of p-toluenesulfonic acid (0.5 g) was refluxed until 2 mol equiv.
of water were collected in a DeaneStark apparatus. The prod-
uct that separated was filtered, washed with methanol and taken
for further reaction. The compounds thus synthesized and their
physical properties are given in Table 1.
5. Spectral data
5.1. 2-Phenyl-N,N0,4-trimethyl-2,10-dihydro-1H-
phenothiazine-1,3-dicarboxamide (4a)
1H NMR (CDCl3): d 1.87 (s, 3H, C4eCH3), 2.66 (d,
J ¼ 4.3 Hz, 3H, C3eCONHCH3), 2.73 (d, J ¼ 4.2 Hz, 3H,
C1eCONHCH3), 3.12 (d, J ¼ 4.9 Hz, 1H, C2eH ), 4.12 (d,
J ¼ 4.9 Hz, 1H, C1eH ), 5.33 (br, 1H, CONH ), 5.78 (br,
1H, CONH ) and 6.77e7.52 ppm (unresolved multiples, 9H,
aromatic-H ).
4.2. Synthesis of 2-aryl-N,N0,4-trimethyl-2,10-dihydro-1H-
phenothiazine-1,3-dicarboxamide (4aeh) and
2-aryl-N,N0,4-trimethyl-10H-phenothiazine-1,
3-dicarboxamide (5aeh)
A mixture of 2-aryl-N,N0,4-trimethyl-6-[(2-sulfanylphe-
nyl)amino]cyclohexa-3,5-diene-1,3-dicarboxamide (3aeh)
(0.01 mol) and dry dimethyl sulfoxide (10 ml) was heated at
110e140 ꢁC for 2e5 h, cooled and poured into water. The
product mixture separated out was filtered, purified through
hexane:ethyl acetate gradient column chromatography. The
products 4aeh and 5aeh were further recrystallized from
methanol and characterized by IR, 1H NMR and mass spectral
studies.
5.2. 2-(2-Methylphenyl)-N,N0,4-trimethyl-2,10-dihydro-1H-
phenothiazine-1,3-dicarboxamide (4b)
1H NMR (CDCl3): d 1.87 (s, 3H, C4eCH3), 2.32 (s, 3H,
CH3 on C2ephenyl), 2.65 (d, J ¼ 4.2 Hz, 3H, NHeCH3),
2.71 (d, J ¼ 4.2 Hz, 3H, NHeCH3), 3.12 (d, J ¼ 4.9 Hz, 1H,
C2eH ), 4.12 (d, J ¼ 4.9 Hz, 1H, C1eH ), 5.32 (br, 1H,
CONH ), 5.80 (br, 1H, CONH) and 6.78e7.54 ppm (unre-
solved multiplets, 8H, aromatic-H ).

Y.S. Sadanandam et al. / European Journal of Medicinal Chemistry 44 (2009) 197e202
201
5.3. 2-(2-Chlorophenyl)-N,N0,4-trimethyl-2,
10-dihydro-1H-phenothiazine-1,3-dicarboxamide (4c)
5.9. 2-Phenyl-N,N0,4-trimethyl-10H-phenothiazine-1,
3-dicarboxamide (5a)
1H NMR (CDCl3): d 1.88 (s, 3H, C4eCH3), 2.67 (d,
J ¼ 4.2 Hz, 3H, NHCH3), 2.70 (d, J ¼ 4.3 Hz, 3H, NHCH3),
3.31 (d, J ¼ 4.8 Hz, 1H, C2eH ), 4.12 (d, J ¼ 4.8 Hz, 1H,
C1eH ), 5.42 (br, 1H, CONH ), 5.90 (br, 1H, CONH ) and
6.77e7.56 ppm (m, 8H, aromatic-H ).
1H NMR (CDCl3): d 2.29 (s, 3H, C4eCH3), 2.51 (d,
J ¼ 4.3 Hz, 3H, C3eCONHeCH3), 2.57 (d, J ¼ 4.3 Hz, C1e
CONHeCH3), 5.10 (br, 2H, CONH on C1 and C3), 6.77e
7.72 (unresolved multiplets, 9H, aromatic-H ) and 8.28 ppm
(s, 1H, exchangeable with D2O, NH ).
5.4. 2-(4-Chlorophenyl)-N,N0,4-trimethyl-2,
10-dihydro-1H-phenothiazine-1,3-dicarboxamide (4d)
5.10. 2-(2-Methylphenyl)-N,N0,4-trimethyl-10H-
phenothiazine-1,3-dicarboxamide (5b)
1H NMR (CDCl3): d 1.88 (s, 3H, C4eCH3), 2.66 (d,
J ¼ 4.2 Hz, 3H, NHeCH3), 2.71 (d, J ¼ 4.3 Hz, 3H, NHe
CH3), 3.29 (d, J ¼ 4.8 Hz, 1H, C2eH ), 4.11 (d, J ¼ 4.8 Hz,
1H, C1eH ), 5.51 (br, 1H, CONH ), 6.04 (br, 1H, CONH )
and 6.80e7.78 ppm (unresolved multiplets, 7H, aromatic-H ).
1H NMR (CDCl3): d 2.29 (s, 3H, C4eCH3), 2.31 (s, 3H,
CH3 on C2ephenyl), 2.51 (d, J ¼ 4.3 Hz, 3H, NHeCH3),
2.57 (d, J ¼ 4.2 Hz, 3H, NHeCH3), 5.30 (br, 2H, CONH ),
6.72e7.20 (unresolved multiplets, 8H, aromatic-H ) and
8.21 ppm (s, 1H, exchangeable with D2O, NH ).
5.5. 2-(2-Methoxyphenyl)-N,N0,4-trimethyl-2,
5.11. 2-(2-Chlorophenyl)-N,N0,4-trimethyl-10H-
10-dihydro-1H-phenothiazine-1,3-dicarboxamide (4e)
phenothiazine-1,3-dicarboxamide (5c)
1H NMR (CDCl3): d 1.88 (s, 3H, C4eCH3), 2.65 (d,
J ¼ 4.1 Hz, 3H, NHeCH3), 2.72 (d, J ¼ 4.1 Hz, 3H, NHe
CH3), 3.31 (d, J ¼ 4.9 Hz, 1H, C2eH ), 3.79 (s, 3H, OCH3),
4.14 (d, J ¼ 4.9 Hz, 1H, C1eH ), 5.53 (br, 1H, CONH ), 6.04
(br, 1H, CONH ) and 6.67e7.51 ppm (unresolved multiplets,
8H, aromatic-H ).
1H NMR (CDCl3): d 2.30 (s, 3H, C4eCH3), 2.52 (d,
J ¼ 4.3 Hz, 3H, NHeCH3), 2.58 (d, J ¼ 4.2 Hz, 3H, NHe
CH3), 5.32 (br, 2H, CONH ), 6.71e7.42 (unresolved multi-
plets, 8H, aromatic-H ) and 8.26 ppm (br, 1H, exchangeable
with D2O, NH ).
5.6. 2-(4-Methoxyphenyl)-N,N0,4-trimethyl-2,
10-dihydro-1H-phenothiazine-1,3-dicarboxamide (4f)
5.12. 2-(4-Chlorophenyl)-N,N0,4-trimethyl-10H-
phenothiazine-1,3-dicarboxamide (5d)
1H NMR (CDCl3): d 1.88 (s, 3H, C4eCH3), 2.65 (d,
J ¼ 4.1 Hz, 3H, NHeCH3), 2.71 (d, J ¼ 4.1 Hz, 3H, NHe
CH3), 3.30 (d, J ¼ 4.8 Hz, 1H, C2eH ), 3.76 (s, 3H, OCH3),
4.12 (d, J ¼ 4.8 Hz, 1H, C1eH ), 5.60 (br, 1H, CONH ), 6.02
(br, 1H, CONH, exchangeable with deuterium) and 7.01e
7.51 ppm (unresolved multiplets, 8H, aromatic-H ). IR (KBr;
n cmꢀ1): 3330 (NH), 1650, 1620 (NHCO). MS: m/z 465 (Mþ).
1H NMR (CDCl3): d 2.31 (s, 3H, C4eCH3), 2.50 (d,
J ¼ 4.2 Hz, 3H, NHeCH3), 2.57 (d, J ¼ 4.2 Hz, 3H, NHe
CH3), 5.36 (br, 2H, CONH ), 6.71e7.62 (unresolved multi-
plets, 7H, aromatic-H ) and 8.28 ppm (br, 1H, exchangeable
with D2O, NH ).
5.13. 2-(2-Methoxyphenyl)-N,N0,4-trimethyl-10H-
phenothiazine-1,3-dicarboxamide (5e)
5.7. 2-(1,3-Benzodioxol-5-yl)-N,N0,4-trimethyl-2,
10-dihydro-1H-phenothiazine-1,3-dicarboxamide (4g)
1H NMR (CDCl3): d 2.30 (s, 3H, C4eCH3), 2.51 (d,
J ¼ 4.1 Hz, 3H, NHeCH3), 2.58 (d, J ¼ 4.2 Hz, 3H, NHe
CH3), 3.81 (s, 3H, OCH3), 5.42 (br, 2H, CONH ), 6.67e7.30
(m, 8H, aromatic-H ) and 8.21 ppm (br, 1H, exchangeable
with D2O, NH ).
1H NMR (CDCl3): d 1.89 (s, 3H, C4eCH3), 2.69 (d,
J ¼ 4.2 Hz, 3H, NHeCH3), 2.74 (d, J ¼ 4.2 Hz, 3H, NHe
CH3), 3.39 (d, J ¼ 4.8 Hz, 1H, C2eH ), 4.14 (d, J ¼ 4.8 Hz,
1H, C1eH ), 5.62 (br, 1H, CONH ), 6.02 (s, 2H, eOeCH2e
Oe), 6.10 (br, 1H, CONH ) and 7.0e7.51 ppm (unresolved
multiplets, 7H, aromatic-H ).
5.14. 2-(4-Methoxyphenyl)-N,N0,4-trimethyl-10H-
phenothiazine-1,3-dicarboxamide (5f)
5.8. 2-(4-Nitrophenyl)-N,N0,4-trimethyl-2,10-dihydro-1H-
phenothiazine-1,3-dicarboxamide (4h)
1H NMR (CDCl3): d 2.30 (s, 3H, C4eCH3), 2.50 (d,
J ¼ 4.1 Hz, 3H, NHeCH3), 2.58 (d, J ¼ 4.2 Hz, 3H, NHe
CH3), 3.80 (s, 3H, OCH3), 5.54 (br, 2H, CONH ), 6.67e7.20
(unresolved multiplets, 8H, aromatic-H ) and 8.94 ppm (br,
1H, exchangeable with D2O, NH ). IR (KBr; n cmꢀ1): 3300
(NH), 1630 (NHCO). MS: m/z 463 (Mþ).
1H NMR (CDCl3): d 1.91 (s, 3H, C4eCH3), 2.70 (d,
J ¼ 4.3 Hz, 3H, NHeCH3), 2.76 (d, J ¼ 4.3 Hz, 3H, NHe
CH3), 3.45 (d, J ¼ 4.9 Hz, 1H, C2eH ), 4.16 (d, J ¼ 4.9 Hz,
1H, C1eH ), 5.63 (br, 1H, CONH ), 6.08 (br, 1H, CONH )
and 7.0e7.94 ppm (unresolved multiplets, 8H, aromatic-H ).

202
Y.S. Sadanandam et al. / European Journal of Medicinal Chemistry 44 (2009) 197e202
5.15. 2-(1,3-benzodioxol-5-yl)-N,N0,4-trimethyl-10H-
phenothiazine-1,3-dicarboxamide (5g)
[6] M. Schenk, A. Bouchon, F. Seibold, C. Muller, J. Clin. Invest. 117 (2007)
3097e3104.
[7] G. Singh, N. Kumar, A.K. Yadav, A.K. Mishra, Heteroat. Chem. 14
(2003) 481e486.
1H NMR (CDCl3): d 2.29 (s, 3H, C4eCH3), 2.56 (d,
J ¼ 4.2 Hz, 3H, NHeCH3), 2.60 (d, J ¼ 4.2 Hz, 3H, NHe
CH3), 5.60 (br, 2H, CONH ), 6.03 (s, 2H, OeCH2eO),
6.60e6.91 (m, 7H, aromatic-H ) and 8.90 ppm (br, 1H, ex-
changeable with D2O, NH ).
[8] A.L. Blobaum, L.J. Marnett, J. Med. Chem. 50 (2007) 1425e1440.
[9] C. Wagner, H.-A. Wagenknecht, Org. Biomol. Chem. 6 (2008) 48e50.
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Heterocyclic Chemistry, vol. 9, Academic Press, New York, 1968, pp.
321e460.
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1079e1083.
5.16. 2-(4-Nitrophenyl)-N,N0,4-trimethyl-10H-
phenothiazine-1,3-dicarboxamide (5h)
[12] K.G. Thomas, V. Biju, P.V. Kamat, M.V. George, D.M. Guldi, Chem.
Phys. Chem. 4 (2003) 1299e1307.
[13] N. Motohashi, M. Kawase, S. Saito, H. Sakagami, Curr. Drug Targets 1
(2000) 237e246.
1H NMR (CDCl3): d 2.31 (s, 3H, C4eCH3), 2.56 (d,
J ¼ 4.2 Hz, 3H, NHeCH3), 2.68 (d, J ¼ 4.2 Hz, 3H, NHe
CH3), 5.84 (br, 2H, CONH ), 6.67e7.95 (unresolved multi-
plets, 8H, aromatic-H ) and 8.56 ppm (br, 1H, exchangeable
with D2O, NH ).
[14] T. Takada, K. Kawai, M. Fujitsuka, T. Majima, J. Am. Chem. Soc. 128
(2006) 11012e11014.
[15] S. Darvesh, R.S. McDolnald, K.V. Darvesh, D. Mataija, S. Conrad,
G. Gomez, R. Walsh, E. Martin, Bioorg. Med. Chem. 15 (2007)
6367e6378.
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(1985) 12e17.
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