1,8-Naphthyridine-3-carboxamide derivatives with anticancer and anti-inflammatory activity

Article abstract of DOI:10.1016/j.ejmech.2009.03.015

A number of 1-propargyl-1,8-naphthyridine-3-carboxamide derivatives (15-35) have been synthesized and screened for their in vitro cytotoxicity and anti-inflammatory activity. Compounds 22, 31 and 34 have shown high cytotoxicity against a number of cancer cell lines, while compound 24 showed significant anti-inflammatory activity.

Full text of DOI:10.1016/j.ejmech.2009.03.015

European Journal of Medicinal Chemistry 44 (2009) 3356–3362
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Preliminary communication
1,8-Naphthyridine-3-carboxamide derivatives with anticancer and anti-
inflammatory activity
,
c
,
b
b
b
b
b
Vivek Kumar a , Manu Jaggi , Anu T. Singh , Alka Madaan , Vinod Sanna , Pratibha Singh ,
*
Pramod K. Sharma c, Raghuveer Irchhaiya c, Anand C. Burman a
,
b
a Chemical Research, Dabur Research Foundation, 22, Site IV, Sahibabad, Ghaziabad 201010, UP, India
b Preclinical Research, Dabur Research Foundation, 22, Site IV, Sahibabad, Ghaziabad 201010, UP, India
c Institute of Pharmacy, Bundelkhand University, Jhansi, India
a r t i c l e i n f o
a b s t r a c t
Article history:
A number of 1-propargyl-1,8-naphthyridine-3-carboxamide derivatives (15–35) have been synthesized
and screened for their in vitro cytotoxicity and anti-inflammatory activity. Compounds 22, 31 and 34
have shown high cytotoxicity against a number of cancer cell lines, while compound 24 showed
significant anti-inflammatory activity.
Received 3 December 2008
Received in revised form
13 February 2009
Accepted 12 March 2009
Available online 24 March 2009
Ó 2009 Elsevier Masson SAS. All rights reserved.
Keywords:
1,8-Naphthyridine
Anti-tumor
Anti-inflammatory
1. Introduction
being not only cytotoxic but also safer on normal cell lines vs. tumor
cells. The C-3 amide linkage in 1,8-naphthyridine-3-carboxamide
Cancer, a disease of worldwide importance, according to the
American Cancer Society, is a group of diseases characterized by
uncontrolled growth and spread of abnormal cells. Recently,
quinolines and 1,8-naphthyridine are being exploited in cancer
chemotherapy and one of the molecules SNS-595 is in second phase
of clinical trials [1,2]. Mammalian Topoisomerase II is one of the
known targets for anti-tumor agents like doxorubicin, etoposide,
ellipticine and amsacrine [3]. 1,8-Naphthyridine derivatives were
found to display moderate cytotoxic activity against murine P388
leukemia, when changes were carried out at N-1 and C-7 positions
[4,5]. However, further structural exploitations in 1,8-naphthyr-
idine skeleton are required to establish a meaningful structure–
activity relationship. Earlier, we have synthesized C-3 carboxamide
derivatives with a spacer, which have shown good cytotoxicity
along with anti-inflammatory activity [6]. Based on these obser-
vations and SAR we have further modified the C-3 carboxamide
acid with different amino acid derivatives (4a–d and 8a–c) to afford
1,8-naphthyridine-3-carboxamide derivatives (15–35). The latter
derivatives may provide hydrophilic interaction, while functional-
ized amino acids may interact with the receptors, and as a conse-
quence, it could trigger physiological response.
Compounds (15–35) have shown promising anticancer activities
and were further tested for their potential anti-inflammatory
activity based on the molecular link between cancer and inflam-
mation [7–9].
2. Chemistry
The synthesis of N-substituted 1,4-dihydro-4-oxo-1-propargyl-
1,8-naphthyridine-3-carboxamide derivatives 15–35 was carried
out using functionalized amino acid derivatives 4a–d and 8a–c. The
synthesis of the racemic 4a–d and 8a–c are described in Scheme 1.
The amino group of DL-3-amino-3-phenyl propionic acid (1) was
protected with Boc anhydride to furnish Boc substituted amino acid
2. The coupling of 2 with appropriate amines, using EDCI–HOBt
provided the respective propionamide 3a–d. The Boc groups of 3a–
d were removed by its treatment with 50% TFA/DCM to yield the
corresponding DL-N-substituted 3-amino-3-phenyl propionamide
(4a–d). Similarly, DL-N-substituted phenyl glycinamide derivatives
(8a–d) were prepared starting from DL-phenyl glycine (5).
* Corresponding author. Chemical Research, Dabur Research Foundation, 22, Site
IV, Sahibabad, Ghaziabad 201010, UP, India. Tel.: þ91 120 4378501; fax: þ91 120
4376905.
The synthesis of compounds 15–34 is shown in Scheme 2.
Commercially available 2-chloro nicotinic acid 9 was reacted with
E-mail address: kumarv@dabur.com (V. Kumar).
0223-5234/$ – see front matter Ó 2009 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2009.03.015

V. Kumar et al. / European Journal of Medicinal Chemistry 44 (2009) 3356–3362
3357
RNH2/
EDCI.HCl/HOBt.H2O/
(Boc)2O
Dioxane/H2O/
NMM
NaOH
O
O
O
R
N
BocHN
OH
BocHN
H2NO
H
n
n
n
H
n
1
1
1
1
0
0
0
R
n
1
0
n
1
0
3a
3b
3c
3d
7a
7b
7c
c-C5H9
c-C6H11
C6H5
2'-Pyridine
c-C5H9
2
6
1
5
c-C6H11
C6H5
n
R
50% TFA/DCM
4a
4b
4c
4d
8a
8b
8c
1
1
1
1
0
0
0
c-C5H9
c-C6H11
C6H5
2'-Pyridine
c-C5H9
O
c-C6H11
C6H5
R
H2N
N
n
H
Scheme 1. Synthesis of functionalized amino acids (4a–d and 8a–c).
1,10-carbonyldiimidazole (CDI) in dry THF to afford the imidazolide
solution, which was allowed to react with ethyl hydrogen malonate
and methyl magnesium bromide to afford nicotinoylacetate 10.
Compound 10 on treatment with triethyl orthoformate and acetic
anhydride (11) followed by the addition of propargyl amine
afforded ethyl nicotinoylacrylate 12. Ethyl 1,8-naphthyridine-3-
carboxylate (13) was prepared by base-assisted (K2CO3) cyclization
of acrylate 12 in ethyl acetate, upon acidic hydrolysis 13; provided
1,8-naphthyridine-3-carboxylic acid 14a, which was treated with
thionyl chloride to afford 14b. The 1-propargyl-1,8-naphthyridine-
O
O
O
O
O
1. N,N'-carbonyl
Triethyl ortho
formate/Ac2O
OEt
OEt
OEt
diimidazole (CDI)
OH
X
X
X
2. Ethyl hydrogen malonate
3. MeMgBr
N
Cl
N
Cl
11
OEt
N
Cl
10
9
NH2/i-Pr2O
O
N
O
O
N
O
O
O
OEt
NH
R'
K2CO3/EtOAc
aq HCl
X
X
N
X
N
N
Cl
12
13
R'
OH
Cl
14a
14b
SOCl2
O
R
H2N
4a-d/ 8a-c
N
H
n
O
O
Ph
O
R
N
H
N
3
n
X
H
8
1
N
N
15-34
Scheme 2. Synthesis of 1,8-naphthyridine-3-carboxamide derivatives (15–34).

3358
V. Kumar et al. / European Journal of Medicinal Chemistry 44 (2009) 3356–3362
Table 1
List of 1-propargyl-1,8-naphthyridine derivatives (15–35).
O
N
O
Ph
O
R
N
H
N
H
n
X
N
15-35
Compound no.
X
n
R
Compound no.
X
n
R
15
16
17
18
19
20
21
22
23
24
25
H
H
H
H
7-Cl
7-Cl
7-Cl
6-F,7-Cl
6-F,7-Cl
6-F,7-Cl
6-F,7-Cl
1
1
1
1
1
1
1
1
1
1
1
c-C5H9
c-C6H11
C6H5
26
27
28
29
30
31
32
33
34
35
H
H
H
7-Cl
7-Cl
7-Cl
0
0
0
0
0
0
0
0
0
0
c-C5H9
c-C6H11
C6H5
c-C5H9
c-C6H11
C6H5
C5H9
C6H11
C6H5
20-Pyridine
c-C5H9
C6H5
20-Pyridine
c-C5H9
c-C6H11
C6H5
20-Pyridine
6-F,7-Cl
6-F,7-Cl
6-F,7-Cl
6-F, 7-pyrrolidine
C6H5
3-carboxamide derivatives 15–34 were prepared by coupling of
appropriate 1,8-naphthyridine-3-carbonyl chloride (14b) with
functionalized amino acids 4a–d and 8a–c, respectively. The N-
substituted 1,4-dihydro-4-oxo-1-propargyl-1,8-naphthyridine-3-
carboxamide derivatives 15–34 are listed in Table 1. Compound 34
on treatment with pyrrolidine in the presence of triethylamine
yielded compound 35 as shown in Scheme 3.
as most cytotoxic molecule against breast cancer cell line with IC50
of 2.0 M in this series. Upon expansion of cyclopentyl ring in
m
compound 22 to cyclohexyl ring (23), cytotoxicity was lowered. The
monohalo aryl substituted derivative (20) and its dihalo substituted
analog 24 exhibited high cytotoxicity on ovarian cancer cell line. In
addition, compound 20 has also shown good cytotoxicity on colon
and pancreas cancer cell lines. The monohalo substituted hetero-
aryl derivative 21 exhibited high cytotoxicity on ovarian and colon
cancer cell lines but its dihalo substituted analog 25 was found
inactive against ovarian cancer cell line. However, compound 25
has resulted in high cytotoxicity against prostate, oral and colon
3. Results and discussion
The synthesized compounds (15–35) are divided into two
classes based on the substitution of phenyl propionamide (4a–d)
and phenyl glycinamide (8a–c) functionalized amino acid into
cancer cell lines with IC50 ꢀ 2.3
mM. These results indicated that the
halo substituted 1-propargyl-1,8-naphthyridine with 3-phenyl
propionamide functionalized amino acid substitution has shown
high cytotoxicity.
N-(2-N-substituted
-1-propargyl-1,8-naphthyridine-3-carboxamide
carbomyl-1-phenylethyl)-1,4-dihydro-4-oxo
(15–25) and
In second series N-(2-N-substituted carbomyl-1-phenylmethyl)-
1,4-dihydro-4-oxo-1-propargyl-1,8-naphthyridine-3-carboxamide
26–35, compounds 26 and 28 were found relatively better than
earlier series derivatives (15–17). However, the monohalo
substituted cycloalkyl derivatives (29 and 30) were found inactive.
The monohalo substituted aryl derivative 31 exhibited high cyto-
toxicity on prostate, oral and leukemia cancer cell lines with IC50 of
N-(2-N-substituted carbomyl-1-phenylmethyl)-1,4-dihydro-4-oxo-
1-propargyl-1,8-naphthyridine-3-carboxamide (26–35) deriva-
tives, respectively. These carboxamides are further divided into
three categories based on the substitution pattern at C-6 and C-7
(unsubstituted: compounds without any substitution at C-6 and
C-7, monohalo substituted: C-7 chloro substituted and dihalo
substituted: C-6 fluoro-C-7 chloro substituted compounds).
1.7, 2.1 and 3.3 mM in this series. Similar to the earlier series dihalo
Amongst compounds (15–25), substitution in 1,8-naphthyridine
ring had played crucial role in eliciting cytotoxicity. Unsubstituted
1,8-naphthyridine derivatives (15–18) were found inactive except
compound 17, which resulted in slight cytotoxicity on prostate
cancer cell line. While, halo substituted derivatives (19–25) were
found better than unsubstituted ones (15–18). The monohalo
substituted cycloalkyl derivative (19) and its dihalo substituted
analog 22 have shown high cytotoxicity on ovary cancer cell line
derivatives (22–24), compounds 32–34 resulted in high cytotox-
icity against a number of cancer cell lines. Compound 32 has shown
broad-spectrum cytotoxicity with IC50 of 1.7 and 3.2 against
pancreas and endothelial cancer cell lines but also exhibited cyto-
toxicity on normal cancer cell line. Compound 33 has shown
selective and high cytotoxicity against ovarian cancer cell line. Aryl
substituted phenyl derivative 34 has shown high and broad spec-
trum of cytotoxicity with IC50 of 0.5, 0.6, 1.1 and 1.4 mM against
with IC50 of 1.1 and 0.68
mM, respectively. Compound 22 was found
O
O
Ph
H
N
NH/Et3N
F
N
H
3
Compound 34
1
N
8
N
O
N
35
Scheme 3. Synthesis of compound 35.

V. Kumar et al. / European Journal of Medicinal Chemistry 44 (2009) 3356–3362
3359
ovarian, prostate, oral and colon cancer cell lines along with good
5.1.2. General procedure for the synthesis of substituted N-tert-
butoxycarbonylamino-3-phenyl-propionamides (3a–d)
safety index. Further, replacement of the C-7 chloro group in
compound 34 with pyrrolidine (35) leads to complete loss of
activity.
Appropriate amine (10 mmol) was added, to a stirred solution of
DL)-3-tert-butoxycarbonylamino-3-phenyl-propionic acid
(
2
It indicated that both phenyl propionamide and phenyl glyci-
namide functionalized amino acid substituted 1-propargyl-1,8-
naphthyridine-3-carboxamides have shown high cytotoxicity on
a number of cancer cell lines particularly on ovary cancer cell line.
The C-6/C-7 halo substituent in the 1,8-naphthyridine played
a crucial role in eliciting cytotoxicity.
(2.65 g, 10 mmol) in dry dichloromethane (50 ml). The resulting
solution was placed in an ice bath for 15 min and 1-hydrox-
ybenzotriazole hydrate (HOBt$H2O, 1.84 g, 12 mmol) and N-meth-
ylmorpholine (NMM, 1.01 g, 10 mmol) were added. The stirring was
continued for 30 min at 0 ꢁC and 1-ethyl-3-(30-dimethylamino-
propyl)carbodiimide hydrochloride (EDCI$HCl, 1.92 g, 10 mmol)
was added. The reaction mixture was stirred for 3 h at 0 ꢁC and at rt
for 5 h. Then, water (50 ml) was added to the mixture, which was
extracted with dichloromethane (100 ml). The organic layer was
dried over anhydrous Na2SO4 and evaporated to afford the crude
residue. The crude product was used in the next step without
further characterization.
Compounds 15, 17, 18, 20, 28 & 34 exhibit >50% inhibition of IL-
1-
28 & 34 at both 1 and 0.1
& 31 demonstrated >50% down regulation of both IL-1-
1 and 0.1 g/ml and suggest promising anti-inflammatory activity.
Compound 24 was found to be most active as it demonstrated
a significant down regulation of TNF- and IP-10 also in addition to
IL-1- & IL-6.
b
at 1
m
g/ml. >50% inhibition of IL-6 was observed by 18, 19, 20,
g/ml. However, compounds 21, 22, 24, 25
and IL-6 at
m
b
m
a
b
5.1.3. General procedure for the synthesis of substituted of 3-amino-
3,N-phenyl-propionamide (4a–d)
50% TFA/DCM (trifluoro acetic acid/dichloromethane, 50 ml)
was added to substituted N-tert-butoxycarbonylamino-3-phenyl-
propionamides (3a–d) (10 mmol) at 0 ꢁC. The reaction mixture was
stirred for 4 h at ambient temperature and then left overnight. The
resulting mixture was neutralized with aqueous NaHCO3 saturated
solution. DCM layer was separated, dried over Na2SO4 and evapo-
rated to afford the crude product. The obtained product was
purified by column chromatography using 2% MeOH/DCM as
eluent.
4. Conclusions
number of 1,8-naphthyridine-3-carboxamide derivatives
(15–35) have been synthesized and evaluated for their in vitro
cytotoxicity and anti-inflammatory activity. Amongst them
compound 34 has shown a high and broad spectrum of cytotoxicity
A
with IC50 of 0.5, 0.6, 1.1 and 1.4 mM against ovarian, prostate, oral
and colon cancer cell lines. Compounds 22 and 31 show significant
cytotoxicity against a number of cancer cell lines, while compound
24 showed significant down regulation of TNF-
a
and IP-10 also in
5.1.3.1. 3-Amino-N-cyclopentyl-3-phenyl-propionamide (4a). Yield:
65.4%; m.p. 113–116 ꢁC; Rf 0.4 (10% MeOH/DCM); 1H NMR (DMSO)
addition to IL-1- and IL-6.
b
d
7.83 (d, 1H, J ¼ 6.99 Hz), 7.34–7.15 (m, 5H), 4.17 (t, 1H, J ¼ 6.80 Hz),
3.95–3.90 (m, 1H), 2.29 (d, 1H, J ¼ 6.87 Hz), 1.72–1.22 (m, 8H); MS
(ESþ) 233 (M þ H).
5. Experimental protocols
5.1. Chemistry
5.1.3.2. 3-Amino-N-cyclohexyl-3-phenyl-propionamide (4b). Yield:
72.4%; m.p. 137–139 ꢁC; Rf 0.5 (5% MeOH/DCM); 1H NMR (CDCl3)
All the solvents and reagents were purchased from companies
such as Aldrich, Lancaster, Acros & Rankem and were used as
supplied. All TLC data (Rf values) were determined on aluminum
sheets coated with silica gel 60 F254 (Merck). Visualization was
achieved with UV light and iodine vapor. Column chromatography
was performed using silica gel (100–200 mesh). 1H NMR spectra
were recorded on a Bruker 300 MHz instrument using tetrame-
thylsilane (TMS) as an internal standard. Mass spectra were recor-
ded on a Micromass Quattro MicroÔ instrument. Elemental
analyses (C, H, N) were undertaken using an elementer analyzer
and were within 0.4% of the calculated values. Melting points were
determined in a capillary tube with a thermal scientific melting
point apparatus Mettler Toledo and are uncorrected.
d
7.40–7.26 (m, 5H), 6.67 (d, 1H, J ¼ 7.1 Hz), 4.53 (s, 1H), 3.79–3.76
(m, 1H), 2.75–2.73 (m, 2H), 2.32 (bs, 2H), 1.84–1.59 (m, 5H), 1.42–
1.05 (m, 5H); MS (ESþ) 247 (M þ H).
5.1.3.3. 3-Amino-3,N-diphenyl-propionamide (4c). Yield: 61.3%;
m.p. 113–116 ꢁC; Rf 0.5 (10% MeOH/DCM); 1H NMR (DMSO)
d 10.05
(s, 1H), 7.54 (d, 2H, J ¼ 7.64 Hz), 7.38 (d, 2H, J ¼ 7.26 Hz), 7.30–7.16
(m, 5H), 7.02–6.97 (m, 1H), 4.30–4.26 (m, 1H), 2.56–2.45 (m, 2H);
MS (ESþ) 241 (M þ H).
5.1.3.4. 3-Amino-3-phenyl-N-pyridin-2-yl-propionamide (4d). Yield:
50.4%; m.p. 108–110 ꢁC; Rf 0.2 (10% MeOH/DCM); 1H NMR (CDCl3)
d
8.24 (d, 1H, J ¼ 8.25 Hz), 7.85 (d, 1H, J ¼ 4.44 Hz), 7.70 (t, 1H,
J ¼ 8.0 Hz), 7.45 (m, 2H), 7.44–7.31 (m, 3H), 4.30 (s, 1H), 2.73–2.71
(m, 2H), 1.66 (bs, 1H); MS (ESþ) 242 (M þ H).
5.1.1. 3-tert-Butoxycarbonylamino-3-phenyl-propionic acid (2)
Di-tert-butyl pyrocarbonate (Boc2O, 2.4 g, 11 mmol) was added
in portions to the stirred solution of (DL)-2-amino phenyl pro-
pionic acid 1 (1.65 g, 10 mmol) in dioxane (20 ml), water (10 ml)
and 1 N NaOH (10 ml) at 0–5 ꢁC. The reaction mixture was stirred
at ambient temperature for 30 min and concentrated in vacuum
to a volume of 10–15 ml. The resulting mixture was cooled to 0–
5 ꢁC, ethyl acetate (30 ml) was added, and the mixture was acid-
ified with dilute hydrochloric acid to pH 2–3. The organic layer
was separated and the aqueous layer was extracted with ethyl
acetate (2 ꢂ 15 ml). The ethyl acetate extracts were combined,
washed with water (2 ꢂ 30 ml), dried over anhydrous Na2SO4 and
concentrated in vacuum to furnish the titled compound, m.p.
143–145 ꢁC.
5.1.4. N-tert-Butoxycarbonylamino-2-phenylglycine (6)
It was prepared in a similar manner as described for the
synthesis of 2 except (DL)-2-phenylglycine (1.51 g, 10 mmol) was
used in place of (DL)-3-aminophenylpropionic acid, m.p. 90–
92 ꢁC.
5.1.5. General procedure for synthesis of 2-N-tert-
butoxycarbonylamino-2-phenyl acetamides (7a–c)
These compounds were similarly prepared as described for 3a–
d, from (DL)-N-tert-butoxycarbonylamino-2-phenylglycine (6) in
place of 2. Compounds were used in the next step without further
characterization.

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V. Kumar et al. / European Journal of Medicinal Chemistry 44 (2009) 3356–3362
5.1.6. General procedure for the synthesis of 2-amino-2-phenyl
acetamides (8a–c)
These compounds were similarly prepared as described for
4a–d, from 2-N-tert-butoxycarbonylamino-2-phenyl acetamides
(7a–c) in place of 3a–d.
J ¼ 8.4 Hz), 7.74–7.64 (m, 2H), 7.43–7.32 (m, 4H), 7.26–7.21 (m, 1H),
7.05–7.03 (m, 1H), 5.60 (q, 1H, J ¼ 7.59, 14.8), 5.40 (d, 2H,
J ¼ 2.37 Hz), 3.51–3.49 (m, 1H), 3.09–2.97 (m, 2H); MS (ESþ) 452
(M þ H).
5.1.7.5. N-(2-N-Cyclopentylcarbomyl-1-phenylethyl)-7-chloro-1,4-dihy-
dro-4-oxo-1-propargyl-1,8-naphthyridine-3-carboxamide (19). Yield:
55.4%; m.p. 208–210 ꢁC; Rf 0.6 (5% MeOH/DCM); 1H NMR (CDCl3)
5.1.6.1. 2-Amino-N-cyclopentyl-2-phenyl acetamide (8a). Yield:
68.9%; m.p. 178–180 ꢁC; Rf 0.6 (5% MeOH/DCM); 1H NMR (DMSO)
d
8.62 (s,1H), 7.42–7.26 (m, 5H), 5.55 (d, 1H, J ¼ 7.96 Hz), 5.11 (s,1H),
d
10.57 (d, 1H, J ¼ 8.01 Hz), 9.15 (s, 1H), 8.73 (d, 1H, J ¼ 8.3),
3.78–3.69 (m, 1H), 1.76–1.00 (m, 8H); MS (ESþ) 219 (M þ H).
7.46–7.22 (m, 5H), 5.75 (d, 1H, J ¼ 7.37), 5.60 (q, 1H, J ¼ 6.7, 14.5 Hz),
5.22–5.21 (m, 2H), 4.17 (q, 1H, J ¼ 6.7, 13.5), 2.78 (d, 2H, J ¼ 6.61),
2.56–2.54 (m, 1H), 1.87–1.79 (m, 2H), 1.59–1.51 (m, 4H), 1.26–1.20
(m, 2H); MS (ESþ) 477 (M þ H).
5.1.6.2. 2-Amino-N-cyclohexyl-2-phenyl acetamide (8b). Yield:
65.3%; m.p. 91–93 ꢁC; Rf 0.4 (5% MeOH/DCM); 1H NMR (DMSO)
d
7.86 (d, 1H, J ¼ 7.86 Hz), 7.36–7.17 (m, 5H), 4.27 (s, 1H), 2.18 (s, 1H),
1.72–1.10 (m, 10H); MS (ESþ) 233 (M þ H).
5.1.7.6. N-(2-N-Phenylcarbomyl-1-phenylethyl)-7-chloro-1,4-dihy-
dro-4-oxo-1-propargyl-1,8-naphthyridine-3-carboxamide (20). Yield:
50.4%; m.p. 220–222 ꢁC; Rf 0.5 (5% MeOH/DCM); 1H NMR (CDCl3)
5.1.6.3. 2-Amino-2,N-diphenyl acetamide (8c). Yield: 53.2%; m.p.
112–114 ꢁC; Rf 0.4 (7% MeOH/DCM); 1H NMR (DMSO)
d
9.99 (bs,1H),
d
10.59 (d, 1H, J ¼ 8.0 Hz), 9.17 (s, 1H), 8.70 (d, 1H, J ¼ 8.3), 8.16 (s,
7.62–7.21 (m, 9H), 7.02 (t, 1H, J ¼ 7.3 Hz), 4.51 (s, 1H); MS (ESþ) 225
1H), 7.51–7.02 (m, 11H), 5.71 (d, 1H, J ¼ 6.1), 5.21 (s, 2H) 3.07–3.00
(m, 2H), 2.56 (s, 1H); MS (ESþ) 485 (M þ H).
(M þ H).
5.1.7. General procedure for the synthesis of N-substituted 1,4-
dihydro-4-oxo-1-propargyl-1,8-naphthyridine-3-carboxamide
derivatives (15–34)
5.1.7.7. N-(2-N-Pyridin-20-ylcarbomyl-1-phenylethyl)-7-chloro-1,4-
dihydro-4-oxo-1-propargyl-1,8-naphthyridine-3-carboxamide (21).
Yield: 52.7%; m.p. 208–210 ꢁC; Rf 0.5 (5% MeOH/DCM); 1H NMR
Thionyl chloride (15 mmol) was added dropwise to a stirred
solution of 1-propargyl-1,8-naphthyridine-3-carboxylic acid (14a,
10 mmol) in dichloromethane (50 ml). The stirring was continued
for 4 h at room temperature and dried under vacuum to provide
acid chloride intermediate 14b. Compound 14b was diluted with
dichloromethane (50 ml) and appropriate amine (15 mmol) was
added to it and stirred for 2 h. To the reaction mixture was added
water (50 ml), which was extracted with dichloromethane
(100 ml). The organic layer was dried over anhydrous Na2SO4 and
concentrated to dryness to provide crude product. The obtained
crude product was purified over silica column using MeOH/DCM as
eluent, to furnish the desired pure compound.
(DMSO)
d
10.58 (s, 1H), 10.27 (d, 1H, J ¼ 8.34 Hz), 9.10 (s, 1H), 9.08
(s, 1H), 8.67 (d, 1H, J ¼ 8.31 Hz), 8.27 (d, 1H, J ¼ 3.6), 8.01 (d, 1H,
J ¼ 8.34 Hz), 7.74–7.69 (m, 2H), 7.42–7.24 (m, 5H), 7.05 (m,1H), 5.60
(q, 1H, J ¼ 7.3, 14.7), 5.30–5.31 (m, 1H), 3.57 (t, 1H, J ¼ 2.3 Hz), 3.12–
2.96 (m, 2H); MS (ESþ) 486 (M þ H).
5.1.7.8. N-(2-N-Cyclopentylcarbomyl-1-phenylethyl)-7-chloro-6-flu-
oro-1,4-dihydro-4-oxo-1-propargyl-1,8-naphthyridine-3-carboxamide
(22). Yield: 67.6%; m.p. 208–210 ꢁC; Rf 0.6 (5% MeOH/DCM); 1H
NMR (CDCl3)
d
10.52 (d, 1H, J ¼ 8.07 Hz), 9.15 (s, 1H), 8.50 (d, 1H,
J ¼ 7.32 Hz), 7.42–7.22 (m, 5H), 5.69 (d, 1H, J ¼ 7.26 Hz), 5.58 (q, 1H,
J ¼ 6.7 Hz, 14.31 Hz), 5.20 (s, 2H), 4.16 (q, 1H, J ¼ 6.9 Hz, 13.6 Hz),
2.78–2.76 (m, 2H), 2.56 (d, 1H, J ¼ 2.5 Hz), 1.87–1.19 (m, 8H); MS
(ESþ) 495 (M þ H).
5.1.7.1. N-(2-N-Cyclopentylcarbomyl-1-phenylethyl)-1,4-dihydro-4-
oxo-1-propargyl-1,8-naphthyridine-3-carboxamide (15). Yield: 39%;
m.p. 193–195 ꢁC; Rf 0.5 (7% MeOH/DCM); 1H NMR (CDCl3)
d
10.61
5.1.7.9. N-(2-N-Cyclohexylcarbomyl-1-phenylethyl)-7-chloro-6-flu-
oro-1,4-dihydro-4-oxo-1-propargyl-1,8-naphthyridine-3-carboxamide
(23). Yield: 67.5%; m.p. 179–181 ꢁC; Rf 0.3 (7% Acetone/CHCl3); 1H
(d, 1H, J ¼ 8.1 Hz), 9.18 (s, 1H), 8.82–8.79 (2H, m), 7.50–7.24 (m, 6H),
5.88 (d, 1H, J ¼ 7.1 Hz), 5.61 (dd, 1H, J ¼ 6.63 Hz), 5.28 (s, 2H), 4.18
(m, 1H), 2.81–2.78 (m, 2H), 2.53 (m, 1H), 1.87–1.49 (m, 6H), 1.28–
1.23 (m, 2H); MS (ESþ) 443 (M þ H).
NMR (CDCl3)
d
10.57 (d, 1H, J ¼ 8.1 Hz), 9.14 (s, 1H), 8.51 (d, 1H,
J ¼ 7.32 Hz), 7.42–7.22 (m, 5H), 5.60–5.51 (m, 2H), 5.20 (d, 2H,
J ¼ 2.5 Hz), 3.75–3.72 (m, 1H), 2.77–2.75 (m, 2H), 2.5 (q, 1H,
J ¼ 2.5 Hz), 1.73–1.5 (m, 4H), 1.30–0.94 (m, 6H); MS (ESþ) 509
(M þ H).
5.1.7.2. N-(2-N-Cyclohexylcarbomyl-1-phenylethyl)-1,4-dihydro-4-
oxo-1-propargyl-1,8-naphthyridine-3-carboxamide
(16). Yield:
62.7%; m.p. 208–210 ꢁC; Rf 0.3 (7% Acetone/CHCl3); 1H NMR (CDCl3)
d
10.64 (d, 1H, J ¼ 8.1 Hz), 9.17 (s, 1H), 8.83–8.81 (m, 2H), 7.50–7.22
5.1.7.10. N-(2-N-Phenylcarbomyl-1-phenylethyl)-7-chloro-6-fluoro-
1,4-dihydro-4-oxo-1-propargyl-1,8-naphthyridine-3-carboxamide
(24). Yield: 50.7%; m.p. 171–173 ꢁC; Rf 0.6 (7% MeOH/DCM); 1H
(m, 6H), 5.70 (m, 2H), 5.28 (s, 2H), 3.75–3.64 (m, 1H), 2.80 (m, 2H),
2.52 (m, 1H), 1.77–0.87 (m, 10H); MS (ESþ) 457 (M þ H).
NMR (DMSO)
d
10.28 (d, 1H, J ¼ 8.2 Hz), 9.98 (s, 1H), 9.1 (1H, s),
5.1.7.3. N-(2-N-Phenylcarbomyl-1-phenylethyl)-1,4-dihydro-4-oxo-
1-propargyl-1,8-naphthyridine-3-carboxamide (17). Yield: 44.1%;
8.62 (d, 1H, J ¼ 7.8 Hz), 7.50 (d, 2H, J ¼ 7.8 Hz), 7.40–7.23 (m, 5H),
7.13–7.11 (m, 3H), 6.98 (t, 1H, J ¼ 7.2 Hz), 5.59 (q, 1H, J ¼ 7.1,
14.2 Hz), 5.30 (s, 1H), 3.56 (s, 1H), 3.01–2.85 (m, 2H); MS (ESþ)
503 (M þ H).
m.p. 185–187 ꢁC; Rf 0.4 (5% MeOH/DCM); 1H NMR (CDCl3)
d 10.68
(d, 1H, J ¼ 7.65 Hz), 9.20 (s, 1H), 8.82–8.78 (m, 2H), 8.24 (s, 1H),
7.60–7.18 (m, 10H), 7.07–7.03 (m, 1H), 5.72 (q, 1H, J ¼ 7.9, 13.6 Hz),
5.35–5.22 (m, 2H), 3.14–2.97 (m, 2H), 2.53 (s, 1H); MS (ESþ) 451
(M þ H).
5.1.7.11. N-(2-N-Pyridin-20-ylcarbomyl-1-phenylethyl)-7-chloro-6-flu-
oro-1,4-dihydro-4-oxo-1-propargyl-1,8-naphthyridine-3-carboxamide
(25). Yield: 37.0%; m.p.196–198 ꢁC; Rf 0.5 (5% MeOH/DCM); 1H NMR
5.1.7.4. N-(2-N-Pyridin-20-ylcarbomyl-1-phenylethyl)-1,4-dihydro-
(DMSO)
d
10.56 (s, 1H), 10.23 (d, 1H, J ¼ 8.34 Hz), 9.10 (s, 1H), 8.60 (d,
4-oxo-1-propargyl-1,8-naphthyridine-3-carboxamide
38.4%; m.p. 228–230 ꢁC; Rf 0.5 (5% MeOH/DCM); 1H NMR (DMSO)
10.56 (s, 1H), 10.35 (d, 1H, J ¼ 8.37), 9.12 (1H, s), 8.96–8.94 (m, 1H),
8.70 (dd, 1H, J ¼ 1.86 Hz), 8.26 (d, 1H, J ¼ 3.84 Hz), 8.02 (d, 1H,
(18). Yield:
1H, J ¼ 7.8 Hz), 8.25 (d, 1H, J ¼ 4.14 Hz), 8.0 (d, 1H, J ¼ 8.34 Hz), 7.69
(m,1H), 7.40–7.30 (m, 4H), 7.22 (t, 1H, J ¼ 7.14 Hz), 7.04 (q, 1H, J ¼ 5.2,
6.8 Hz), 5.58 (q,1H, J ¼ 7.4,14.2 Hz), 5.31–5.30 (d, 2H, J ¼ 2.1 Hz), 3.56
(t, 1H, J ¼ 2.14 Hz), 3.10–2.95 (m, 2H); MS (ESþ) 504 (M þ H).
d

V. Kumar et al. / European Journal of Medicinal Chemistry 44 (2009) 3356–3362
3361
5.1.7.12. N-(2-N-Cyclopentylcarbomyl-1-phenylmethyl)-1,4-dihydro-
4-oxo-1-propargyl-1,8-naphthyridine-3-carboxamide (26). Yield:
52.5%; m.p. 215–217 ꢁC; Rf 0.4 (2% MeOH/DCM); 1H NMR (CDCl3)
5.1.7.20. N-(2-N-Phenylcarbomyl-1-phenylmethyl)-7-chloro-6-flu-
oro-1,4-dihydro-4-oxo-1-propargyl-1,8-naphthyridine-3-carboxamide
(34). Yield: 52.8%; m.p. >250 ꢁC; Rf 0.4 (7% Acetone/CHCl3); 1H
d
10.77 (d, 1H, J ¼ 6.5 Hz), 9.16 (s, 1H), 8.81 (d, 1H, J ¼ 6.6 Hz), 7.51–
NMR (DMSO)
d
10.61 (d, 1H, J ¼ 7.5 Hz),10.49 (s,1H), 9.1 (s,1H), 8.66
7.30 (m, 5H), 5.83 (d, 1H, J ¼ 6.7 Hz), 5.61 (d, 1H, J ¼ 6.9 Hz), 5.27
(q, 2H, J ¼ 2.4, 4.8 Hz), 4.22 (d, 2H, J ¼ 6.9 Hz), 2.52 (d, 2H,
J ¼ 2.3 Hz), 1.97–1.92 (m, 2H), 1.60–1.25 (m, 6H); MS (ESþ) 429
(M þ H).
(d, 1H, J ¼ 7.7 Hz), 7.59–7.45 (m, 4H), 7.41–7.26 (m, 5H), 7.07–7.02
(m, 1H), 5.87 (d, 1H, J ¼ 7.5 Hz), 5.32 (d, 2H, J ¼ 2.3 Hz), 3.57 (d, 1H,
J ¼ 2.38 Hz); MS (ESþ) 489 (M þ H).
5.1.7.21. N-(2-N-Phenylcarbomyl-1-phenylmethyl)-6-fluoro-7-pyrro-
lidinyl-1,4-dihydro-4-oxo-1-propargyl-1,8-naphthyridine-3-carbox-
amide (35). Triethylamine (1.1 g, 11 mmol) and pyrrolidine
(2.13 g, 30 mmol) were added to a suspension of compound 34
(4.89 g, 10 mmol) in acetonitrile (50 ml) and refluxed for 3 h. The
reaction mixture was cooled; the precipitate thus separated was
collected by filtration, washed with acetonitrile and dried to give
compound 35. Yield 4.52 g (86.3 %). m.p. >250 ꢁC; Rf 0.4 (2%
5.1.7.13. N-(2-N-Cyclohexylcarbomyl-1-phenylmethyl)-1,4-dihydro-
4-oxo-1-propargyl-1,8-naphthyridine-3-carboxamide
(27). Yield:
65.6%; m.p. 206–208 ꢁC; Rf 0.4 (7% Acetone/CHCl3); 1H NMR (CDCl3)
d
10.66 (d, 1H, J ¼ 6.21 Hz), 9.16 (s, 1H), 8.81 (d, 2H, J ¼ 6.7 Hz), 7.51–
7.26 (m, 6H), 5.70 (d, 2H, J ¼ 8.3 Hz), 5.61 (d, 1H, J ¼ 7.09 Hz), 5.28–
5.20 (m, 2H), 3.81–3.75 (m, 1H), 2.80–2.78 (m, 1H), 2.51 (d, 1H,
J ¼ 2.5 Hz), 2.02–1.63 (m, 3H) 1.63–1.02 (m, 7H); MS (ESþ) 443
(M þ H).
Methanol/DCM); 1H NMR (DMSO)
d
10.98 (d, 1H, J ¼ 7.4 Hz), 10.45
(s, 1H), 8.8 (s, 1H), 7.98–7.94 (m, 1H), 7.59–7.26 (m, 9H), 7.04 (s,
1H), 5.85 (d, 1H, J ¼ 7.9 Hz), 5.23 (s, 2H), 3.75 (bs, 4H), 3.45 (s, 1H),
1.94 (s, 4H); MS (ESþ) 523 (M þ H).
5.1.7.14. N-(2-N-Phenylcarbomyl-1-phenylmethyl)-1,4-dihydro-4-oxo-
1-propargyl-1,8-naphthyridine-3-carboxamide (28). Yield: 66.0%;
m.p. 187–189 ꢁC; Rf 0.5 (5% MeOH/DCM); 1H NMR (DMSO)
d 10.73
(d, 1H, J ¼ 5.82 Hz), 10.51 (s, 1H), 9.15 (s,1H), 8.96 (s,1H), 8.73 (d,1H,
J ¼ 7.35 Hz), 7.68–7.29 (m, 10H), 7.04 (s, 1H), 5.89 (d, 1H, J ¼ 7.4 Hz),
5.41 (bs, 2H), 3.51 (s, 1H); MS (ESþ) 437 (M þ H).
5.2. Biological activity
5.2.1. Cytotoxicity
All the synthesized derivatives 15–35 were tested for in vitro
cytotoxicity on nine cancerous as well as a non-cancerous cell lines
5.1.7.15. N-(2-N-Cyclopentylcarbomyl-1-phenylmethyl)-7-chloro-1,4-
dihydro-4-oxo-1-propargyl-1,8-naphthyridine-3-carboxamide (29).
Yield: 75.5%; m.p. 191–193 ꢁC; Rf 0.3 (2% MeOH/DCM); 1H NMR
and IC50 values were calculated in micromole (mM) [10]. The human
cancer cell lines used in the study are ovary (PA1), prostate
(DU145), oral (KB), colon (SW620), breast (HBL100), lung (A549),
pancreas (MIAPaCa2), leukemia (K562) and endothelial (ECV304)
cancer. All the 1,8-naphthyridine 15–35 and assay standard Doxo-
rubicin HCl were also tested against normal mouse fibroblast
(NIH3T3) cell line to evaluate their cancer cell specificity (safety
index). The cytotoxicity data are summarized in Table 2.
Compounds, which were found inactive, are not listed in Table 2.
Derivatives of 1,8-naphthyridine-3-carboxamide (15–35) were
screened for cytotoxic activity at the highest soluble concentration
(DMSO)
d
10.52 (s, 1H), 9.09 (s, 1H), 8.69 (d, 1H, J ¼ 7.02 Hz), 8.38 (d,
1H, J ¼ 9.36 Hz), 7.70 (d, 1H, J ¼ 9.75 Hz), 7.40–7.27 (m, 5H), 5.65 (s,
1H), 5.34–5.27 (m, 2H), 3.93 (s, 1H), 3.54–3.52 (m, 1H), 1.82–1.11 (m,
8H); MS (ESþ) 463 (M þ H).
5.1.7.16. N-(2-N-Cyclohexylcarbomyl-1-phenylmethyl)-7-chloro-1,4-di
hydro-4-oxo-1-propargyl-1,8-naphthyridine-3-carboxamide (30). Yield:
64.4%; m.p. >250 ꢁC; Rf 0.4 (7% Acetone/CHCl3); 1H NMR (DMSO)
d
10.52 (d, 1H, J ¼ 7.8 Hz), 9.09 (s, 1H), 8.69 (d, 1H, J ¼ 8.4 Hz), 8.32 (d,
1H, J ¼ 7.74 Hz), 7.71 (d, 1H, J ¼ 8.2 Hz), 7.43–7.16 (m, 5H), 5.68 (d, 1H,
J ¼ 7.8 Hz), 5.30 (d, 2H, J ¼ 1.83 Hz), 3.55 (s, 2H), 1.78–1.49 (m, 5H),
1.26–0.83 (m, 5H); MS (ESþ) 477 (M þ H).
of 10 mM and on four lower concentrations on nine human tumor
and one non-tumorous cell lines.
Briefly, a three days MTT in vitro cytotoxicity assay was per-
formed, which is based on the principle of uptake of MTT
(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide),
a tetrazolium salt by the metabolically active cells. MTT is metab-
olized by active mitochondria into a blue colored formazan product
that is read spectrophotometrically at 540 nm. MTT solution
(5 mg/ml) was prepared in phosphate buffered saline, pH 7.4 and
5.1.7.17. N-(2-N-Phenylcarbomyl-1-phenylmethyl)-7-chloro-1,4-dihy-
dro-4-oxo-1-propargyl-1,8-naphthyridine-3-carboxamide (31). Yield:
65.1%; m.p. >250 ꢁC; Rf 0.5 (5% MeOH/DCM); 1H NMR (DMSO)
d
10.66 (d, 1H, J ¼ 7.5 Hz), 10.50 (s, 1H), 9.14 (s, 1H), 8.72 (d, 1H,
J ¼ 8.37 Hz), 7.73 (d, 1H, J ¼ 8.34 Hz), 7.61–7.54 (m, 4H), 7.43–7.28
(m, 5H), 7.08–7.03 (m, 1H), 5.89 (d, 2H, J ¼ 7.4 Hz), 5.33 (d, 1H,
J ¼ 1.58 Hz), 3.58 (s, 1H); MS (ESþ) 471 (M þ H).
filtered through a 0.22-mm filter. For each type of tumor and normal
cell, 5000–10,000 cells were seeded in a 96-well culture plate and
treated with various concentrations of 1,8-naphthyridine-3-car-
boxamide derivatives (15–35) for an incubation period of 72 h in
CO2 incubator. Control cells were not treated with 1,8-naphthyr-
idine-3-carboxamide derivatives. The assay was terminated after
5.1.7.18. N-(2-N-Cyclopentylcarbomyl-1-phenylmethyl)-7-chloro-6-
fluoro-1,4-dihydro-4-oxo-1-propargyl-1,8-naphthyridine-3-carbox-
amide (32). Yield: 65.0%; m.p. 238–240 ꢁC; Rf 0.4 (7% Acetone/
CHCl3); 1H NMR (DMSO)
d
10.41 (d, 1H, J ¼ 7.83 Hz), 9.04 (s, 1H),
72 h by adding 125
mg (25 ml) MTT to each well. After incubation for
8.57 (d, 1H, J ¼ 7.83 Hz), 8.32 (d, 1H, J ¼ 7.17 Hz), 7.34 (d, 2H,
J ¼ 7.35 Hz), 7.28–7.16 (m, 3H), 5.58 (d, 1H, J ¼ 7.8 Hz), 5.25 (d, 2H,
J ¼ 2.3 Hz), 3.93–3.84 (m, 1H), 3.50 (t, 1H, J ¼ 2.3 Hz), 1.63–1.17 (m,
8H); MS (ESþ) 481 (M þ H).
3 h, 50 l of 10% SDS–0.01 N HCl was added to each well to lyse the
m
cells and dissolve formazan. Plate was read spectrophotometrically
at 540 nm after 1 h. Cytotoxicity percentage was calculated using
the following formula: Cytotoxicity percentage ¼ (1 ꢃ (X/R1)) ꢂ 100,
where X ¼ (absorbance of treated sample at 540 nm) ꢃ (absorbance
of blank at 540 nm), R1 ¼ absorbance of control sample at 540 nm.
5.1.7.19. N-(2-N-Cyclohexylcarbomyl-1-phenylmethyl)-7-chloro-6-flu-
oro-1,4-dihydro-4-oxo-1-propargyl-1,8-naphthyridine-3-carboxamide
(33). Yield: 57.1%; m.p. >250 ꢁC; Rf 0.5 (7% Acetone/CHCl3); 1H NMR
5.2.2. Anti-inflammatory activity
(DMSO)
d
10.47 (d, 1H, J ¼ 8.31 Hz), 9.11 (s, 1H), 8.64 (d, 1H,
Dendritic cells (DCs) are central to an immune response and
function as the best antigen-presenting cells. DCs have been iden-
tified as the cellular target for understanding pharmacological role
of various immunomodulatory agents [11,12]. Pro-inflammatory
J ¼ 6.18 Hz), 8.31 (d, 1H, J ¼ 7.89 Hz), 7.43–7.25 (m, 5H), 5.67 (d, 1H,
J ¼ 7.65 Hz), 5.32 (d, 2H, J ¼ 2.3 Hz), 3.56–3.48 (m, 2H), 1.77–1.04 (m,
10H); MS (ESþ) 495 (M þ H).

3362
V. Kumar et al. / European Journal of Medicinal Chemistry 44 (2009) 3356–3362
Table 2
In vitro cytotoxicity of 1-propargyl-1,8-naphthyridine-3-carboxamide derivatives (15–35).
Compound no.
IC50
PA1
(mM)
DU145
(prostate)
KB
(oral)
SW620
(colon)
HBL100
(breast)
A549
(lung)
MIAPaCa2
(pancreas)
K562
(leukemia)
ECV304
(endothelial)
NIH3T3
(normal fibroblast)
(ovary)
Doxorubicin
0.63
>10
1.1
0.54
1.7
0.68
2.3
2.1
>10
>10
8.9
>10
1.8
0.10
7.2
>10
>10
4.9
>10
8.03
5.9
2.1
>10
8.8
1.7
3.2
3.0
>10
>10
>10
5.2
0.08
>10
2.7
2.9
2.9
2.1
>10
5.7
0.24
>10
3.2
4.0
>10
2.0
>10
9.3
>10
>10
>10
7.8
5.1
>10
>10
0.08
>10
9.5
>10
>10
6.1
>10
>10
>10
>10
>10
>10
>10
>10
>10
0.15
>10
2.4
3.0
>10
4.4
4.9
6.9
>10
>10
>10
9.7
0.10
>10
6.8
7.7
5.9
7.3
6.2
6.6
>10
>10
>10
3.3
5.9
>10
5.0
NA
>10
7.8
4.0
>10
5.1
0.39
NA
4.4
4.4
NA
2.4
NA
9.7
4.2
NA
NA
NA
0.4
7.4
NA
17
19
20
21
22
23
24
25
26
28
31
32
33
34
4.9
>10
>10
2.3
4.5
3.0
2.1
3.5
>10
1.1
9.8
>10
>10
>10
>10
>10
3.2
2.3
>10
>10
2.2
3.4
>10
1.4
1.7
>10
>10
1.8
0.5
>10
0.6
>10
9.1
NA – not active. Cytotoxicity was assessed by MTT assay as described in Methods. Data shown are IC50 of single independent experiments done in triplicate. If IC50 was not
achieved even at the highest concentration tested i.e. 10 mM, it was represented as NA.
Table 3
Table 4
Down regulation of IL-1-
b
and IL-6 activity by 1-propargyl-1,8-naphthyridine-3-
Down regulation of TNF-a and IP-10 activity by 1-propargyl-1,8-naphthyridine-3-
carboxamide derivatives (% change calculated with reference to LPS stimulated
levels secreted by DCs).
carboxamide derivatives (% change calculated with reference to LPS stimulated
levels secreted by DCs).
Compound no.
IL-1-
b
(% inhibition)
0.1
IL-6 (% inhibition)
Compound no.
TNF-
a
(% inhibition)
0.1
IP-10 (% inhibition)
g/ml 0.1 mg/ml
1
mg/ml
m
g/ml
1
m
g/ml
0.1
mg/ml
1
m
g/ml
m
g/ml
1
m
15
17
18
19
20
21
22
24
25
28
31
34
ꢃ52.1
ꢃ78.5
ꢃ50.1
ꢃ18.1
ꢃ62.4
ꢃ75.1
ꢃ34.1
ꢃ82.0
ꢃ28.3
ꢃ57.3
ꢃ83.4
ꢃ84.8
ꢃ83.4
ꢃ39.9
ꢃ82.0
ꢃ44.3
–
–
–
–
15
17
24
ꢃ34.7
ꢃ29.7
ꢃ99.0
ꢃ19.3
ꢃ19.1
ꢃ80.0
ꢃ25.0
ꢃ33.1
ꢃ38.8
ꢃ31.7
ꢃ17.3
ꢃ74.9
ꢃ81.7
ꢃ75.4
ꢃ82.9
ꢃ100.0
ꢃ96.0
ꢃ99.1
ꢃ79.3
ꢃ91.7
ꢃ99.9
ꢃ74.4
ꢃ79.8
ꢃ69.5
ꢃ78.2
ꢃ80.1
ꢃ60.0
ꢃ75.5
ꢃ79.3
ꢃ76.5
ꢃ84.4
ꢃ102.4
Cytokine levels were estimated by ELISA as described in Methods. Data shown are
percent inhibition of cytokine/chemokine in duplicate.
ꢃ99.4
ꢃ82.0
ꢃ102.0
ꢃ106.8
ꢃ109.6
ꢃ64.6
ꢃ86.3
ꢃ97.0
(R&D Systems Inc, MN, USA). Compounds showing down regula-
tion of one or more of the cytokines or chemokines by >25% were
considered to have potential anti-inflammatory activity as shown
in Tables 3 and 4.
cytokines are being explored as potential targets in therapeutic
interventions for various inflammatory disorders such as Rheu-
matoid Arthritis [13]. In the present study, various derivatives were
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evaluated for down regulation of IL-1-
secreted by LPS stimulated DCs.
b, IL-6, TNF-a and IP-10 levels
Primary DC cultures were generated from femoral bone
marrow of 8–12 weeks old C57BL/6 mice [14]. Percent change in
cytokine/chemokine ¼ {(B ꢃ A)/A ꢂ 100, where B ¼ concentration
of cytokine/chemokine (pg/ml) secreted by LPS stimulated DCs
when incubated with test molecule, A ¼ concentration of cytokine/
chemokine (pg/ml) secreted by LPS stimulated DCs alone. Bone
marrow progenitors were cultured in RPMI-1640 supplemented
with 10% FBS (Hyclone) and 20 ng/ml rmGMCSF (R&D Systems,
MN, USA) at 37 ꢁC, 5% CO2. Immature DCs at day 6 were stimulated
with 10 ng/ml lipopolysaccharide (LPS; SIGMA) and incubated
with the 1-propargyl-1,8-naphthyridine-3-carboxamide deriva-
tives at two concentrations, 0.1 and 1
and IL-6, TNF- and IP-10 secreted by the DCs were measured in
culture supernatants by Enzyme Linked Immunosorbent Assays
mg/ml for 24 h. The IL-1-
b
a