Design, synthesis and molecular modeling of biquinoline-pyridine hybrids as a new class of potential EGFR and HER-2 kinase inhibitors

Article abstract of DOI:10.1016/j.bmcl.2014.07.094

A new series of biquinoline-pyridine hybrids were designed and synthesized by a base-catalyzed cyclocondensation through one-pot multicomponent reaction. All compounds were tested for in vitro anticancer activities against two cancer cell lines A549 (adenocarcinomic human alveolar basal epithelial) and Hep G2 (liver cancer). Enzyme inhibitory activities of all compounds were carried out against EGFR and HER-2 kinase. Of the compounds studied, majority of the compounds showed effective anticancer activity against used cancer cell lines. Compound 9i (IC₅₀= 0.09 μM) against EGFR and (IC₅₀= 0.2 μM) against HER-2 kinase displayed the most potent inhibitory activity as compared to other member of the series. In the molecular modelling study, compound 9i was bound in to the active pocket of EGFR with four hydrogen bonds and two π-cation interactions having minimum binding energy ΔG_b= -54.4 kcal/mol.

Full text of DOI:10.1016/j.bmcl.2014.07.094

Bioorganic & Medicinal Chemistry Letters 24 (2014) 4472–4476
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Design, synthesis and molecular modeling of biquinoline–pyridine
hybrids as a new class of potential EGFR and HER-2 kinase inhibitors
Chetan B. Sangani, Jigar A. Makawana, Yong-Tao Duan, Yong Yin, Shashikant B. Teraiya,
⇑
Nilesh J. Thumar, Hai-Liang Zhu
State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210093, People’s Republic of China
a r t i c l e i n f o
a b s t r a c t
Article history:
A new series of biquinoline–pyridine hybrids were designed and synthesized by a base-catalyzed cyclo-
condensation through one-pot multicomponent reaction. All compounds were tested for in vitro antican-
cer activities against two cancer cell lines A549 (adenocarcinomic human alveolar basal epithelial) and
Hep G2 (liver cancer). Enzyme inhibitory activities of all compounds were carried out against EGFR
and HER-2 kinase. Of the compounds studied, majority of the compounds showed effective anticancer
Received 12 May 2014
Revised 29 July 2014
Accepted 31 July 2014
Available online 9 August 2014
activity against used cancer cell lines. Compound 9i (IC50 = 0.09 lM) against EGFR and (IC50 = 0.2 lM)
against HER-2 kinase displayed the most potent inhibitory activity as compared to other member of
the series. In the molecular modelling study, compound 9i was bound in to the active pocket of EGFR with
Keywords:
Tetrazolo[1,5-a]quinoline-4-carbaldehyde
biquinoline
Pyridine
One-pot reaction
Anticancer activity
Molecular modeling
four hydrogen bonds and two
mol.
p
–cation interactions having minimum binding energy
DG
b
= À54.4 kcal/
Ó 2014 Elsevier Ltd. All rights reserved.
Along with the living habits and environment changes, cancer
has become the major cause of death in both developing and devel-
oped countries. Until now one significant way to induce the occur-
adverse, radiotherapy and chemotherapy resistance and tumor
angiogenesis.
9
1
Quinoline moiety is found in a large variety of naturally occur-
ring compounds and also chemically useful synthons bearing
rence of cancers is still by mutation or mis-regulation of cell cycle
regulatory genes and proteins to guide an abnormal control of cell
1
0–20
21
diverse bioactivities
including EGFR inhibitory activity. Also,
2
proliferation. Epidermal growth factor receptor (EGFR) is a kind of
no one can ignore the role of pyridine as an appreciable pharmaco-
tyrosine kinase firstly reported in the literature.3 It has become
one of the targets of anticancer drug research and development
because of it is wide distribution in the cell and important role in
cell life. EGFRs are distributed in mammalian epithelial cell mem-
branes and have relationships with cell proliferation, death, and
differentiation. They are junctions to deliver extracellular growth
signals to intracellular. EGFR family comprise four members,
including: EGFR (HER1/ErbB-1), ErbB-2 (HER2/neu), ErbB-3
,4
phore for antimicrobial and anticancer activity
22,23
including EGFR
2
4
inhibitory activity. Moreover, multi-component reactions were
employed as a powerful tool to synthesize diverse and complex
heterocyclic compounds due to their advantages of the intrinsic
atom economy, simpler procedures, structural diversity, energy
2
5–27
savings, and reduced waste.
Encouraged by potential clinical
applications of quinoline and pyridine a modification on the 1
and 4-position on 4H-quinoline by pyridine and tetrazolo[1,5-
a]quinoline-4-carbaldehyde, respectively, may bring significant
changes in pharmacological activities and may provide new classes
of therapeutically active compounds, with this hope and as a part of
(
HER3), and ErbB-4 (HER4).5 EGFR tyrosine kinase-mediated cell
growth signaling pathway plays an important role in the formation
and development of many types of solid tumors, such as nonsmall
6
7
8
cell lung cancer, head and neck cancer and glioblastomas. Over
expression of EGFR family receptors have always been observed in
our current studies in developing new therapeutically active agents
via combination of two therapeutically active moieties,2
8–30
we
6
these tumors, approximately in 60% of all tumors. EGFR and ErbB-
report herein the preparation of N-pyridinyl-4H-quinoline 9a–l
derivatives via MCR approach that is, one pot base catalyzed cyclo-
condensation reaction of tetrazolo[1,5-a]quinoline-4-carbalde-
hyde, malononitrile/methylcyanoacetate/ethylcyano acetate and
b-pyridinyl enaminone. The synthetic approach adopted to obtain
the target compounds is depicted in Scheme 1. The starting mate-
rial tetrazolo[1,5-a]quinoline-4-carbaldehyde 4a–d was prepared
2
are the most well studied targets in current research and their
over expression or abnormal activation often cause cell malignant
transformation. Also they have relationship with postoperative
⇑
Corresponding author. Tel.: +86 25 8359 2572; fax: +86 25 8359 2672.
E-mail address: zhuhl@nju.edu.cn (H.-L. Zhu).
http://dx.doi.org/10.1016/j.bmcl.2014.07.094
960-894X/Ó 2014 Elsevier Ltd. All rights reserved.
0

C. B. Sangani et al. / Bioorg. Med. Chem. Lett. 24 (2014) 4472–4476
4473
Scheme 1. Synthetic pathway for the compounds 9a–l.
according to literature procedure.31 The required 3-(pyridin-3-yla-
mino)cyclohex-2-enones 7 was synthesized by nucleophilic addi-
tion reaction of 1,3-cyclohexane dione 5 and 3-amino pyridine 6
at 120 °C for 30 min under solvent free condition. The title com-
pounds 9a–l were prepared via one-pot three component cyclo-
absorption bands for all the compounds were observed in the
range of 3450–3355 and 3185–3145 cm corresponding to asym-
À1
metrical and symmetrical stretching of ANH
2
group and 2200–
2180 cm for AC„N group. In H NMR spectra of compounds
9a–l, a sharp singlet peak of methine proton (H ) was appeared
28
À1
1
4
condensation reaction between 4a–d,
7
and malononitrile/
around d 5.14–5.42 ppm and disappearance of ACHO proton at d
10.15 ppm clearly indicate the formation of 4H-quinoline forma-
tion. A most characteristic positive signal observed around d
methylcyanoacetate/ethylcyanoacetate 8a–c in ethanol containing
a catalytic amount of piperidine in good to excellent yields.
The structural elucidation of the synthesized compounds 9a–l
was carried out by FT-IR, 1H NMR, C NMR, elemental analysis
and mass spectrometry. In FT-IR spectra, compounds 9a–l exhib-
34.55–35.18 ppm was indicated methane carbon (C
4
) in 13C NMR
13
spectra of compounds 9a–l which confirm the formation of 4H-
quinoline ring. Also the signal at around d 59.42–59.70 ppm is
assigned to carbon attached with carbonitrile and d 77.84–
78.33 ppm is assigned to carbon attached with carboxylate group.
À1
ited an absorption band around 1640–1680 cm for (C@O, C@N)
À1
stretching and 760–750 cm for CACl group. The characteristic
Table 1
Inhibition of EGFR kinase and antiproliferative activity IC50
(l
M) of compounds 9a–l
IC50
(lM)
Compound
EGFR
SI = log10(C ctr./C test)
HER-2
SI = log10(C ctr./C test)
A549
Hep G2
9
9
9
9
9
9
9
9
9
9
9
9
a
b
c
d
e
f
g
h
i
4.8
10.4
5.4
18.3
1.1
4.3
1.3
8.1
0.09
7.0
0.2
À2.2
À2.5
À2.2
À2.8
À1.6
À2.1
À1.6
À2.4
À0.5
À2.4
À0.8
À2.7
—
5.2
14.8
8.9
19.3
1.9
5.2
2.1
9.0
0.2
4.1
0.8
22.7
0.2
À1.4
À1.9
À1.6
À2.0
À0.1
À1.4
À1.0
À1.6
0
À1.3
À0.6
À2.0
—
13.0
18.1
23.1
7.8
1.1
5.4
6.4
0.1
0.4
8.5
11.0
16.1
21.2
5.9
1.5
1.9
6.0
1.3
0.1
7.1
j
k
l
15.4
1.3
0.1
18.3
5.5
0.1
16.7
0.03
Erlotinib

4
474
C. B. Sangani et al. / Bioorg. Med. Chem. Lett. 24 (2014) 4472–4476
Table 2
Binding energy of compounds 9a–l with EGFR
investigation of antiproliferative activity of compounds 9a–l, it
has been observed that against A549, compounds 9e (IC50 = 1.1 -
Compounds
Binding energy
D
G
b
lM), 9h (IC50 = 0.1 lM), 9i (IC50 = 0.4 lM) and 9l (IC50 = 1.3 lM)
showed most potent activity as compared to other compounds of
the series and less comparable to the positive control erlotinib
9
a
À44.5
À43.5
À48.4
À44.5
À53.5
À50.5
À47.6
À51.4
À54.5
À50.1
À48.6
À45.6
9b
9
c
(IC50 = 0.1
and 9i (IC50 = 0.1
e (IC50 = 1.5 M) and 9f (IC50 = 2.0
compared to other compounds of the series and less comparable
to the positive control erlotinib (IC50 = 0.1 M).
As shown in Table 1, against EGFR, compound 9i (IC50 = 0.09
displayed the most potent inhibitory activity as well as compounds
e (IC50 = 1.1 M), 9g (IC50 = 1.3 M) and 9k (IC50 = 0.2 M) showed
excellent activity as compared to other compounds of the series and
less comparable to the positive control erlotinib (IC50 = 0.03 M),
while against HER-2, compound 9i (IC50 = 0.2 M) displayed the
most potent inhibitory activity as well as compounds 9e
IC50 = 1.9 M), 9g (IC50 = 2.1 M) and 9k (IC50 = 0.8 M) showed
l
M), while against Hep G2 compounds 9h (IC50 = 1.3
M) showed most potent activity and compounds
M) showed good activity as
lM)
9d
l
9
9
e
f
9
l
l
9g
9h
l
9
9
i
j
lM)
9k
9
l
l
l
9
l
l
l
In 13C NMR spectra, the negative signals around d 169.25–169.53
and 194.11–195.70 were arise for the carbonyl carbon (C@O) of
ester and cyclohexenone ring, respectively. The obtained elemental
analysis values are in consonance with theoretical data. Mass spec-
tra of title compounds showed expected molecular ion peak M
corresponding with proposed molecular mass.
All compounds were tested against EGFR and HER-2 kinases as
well as against A549 (adenocarcinomic human alveolar basal
epithelial) and Hep G2 (liver cancer) cell lines (Table 1). Upon
(
l
l
l
excellent activity as compared to other compounds of the series
and less comparable to the positive control erlotinib
+
(
IC50 = 0.2
lM).
Structure activity relationship (SAR) was carried out from EGFR
and HER-2 kinase and anticancer activities against two cancer cell
lines A549 and Hep G2. According to the activity data, it has been
1
2
observed that the change in R and R substitution may lead to
Figure 1. 3D binding model of compound 9i into the active pocket of EGFR.

C. B. Sangani et al. / Bioorg. Med. Chem. Lett. 24 (2014) 4472–4476
4475
Figure 2. 2D binding model of compound 9i into the active pocket of EGFR.
change in the activity against employed cancer cells as well
ring at N-1 position for aiming their potent anticancer activities.
Some magnificent biological results have been obtained with the
biquinoline–pyridine hybridized scaffold and it has been con-
cluded that majority of the compounds showed effective antican-
cer activities. In the case of inhibitory activity, compounds 9i
against EGFR and HER-2 kinase have found to be most effective
members of the series. According to this, it is worthy to mention
that the biquinoline–pyridine hybrids as a useful template for fur-
ther development of more anticancer compounds that deserve fur-
ther investigation and derivatization in order to discover the scope
and limitation of its biological activities.
Camptothecin is anti cancer drug having quinoline nucleus and
our synthesized compound having main nucleus is quinoline. So
with this hope we described the possible mode of action of synthe-
sized quinoline derivative acts as anti cancer same like
camptothecin.
1
as EGFR and HER-2 kinase. Compounds having R = AH and
2
R = ACOOEt (Compound 9i) have proved as most effective mem-
bers against EGFR and HER-2 kinase and the activity in deceasing
1
2
order for R substitution is H > OCH
3
> CH
3
> Cl and for R substitu-
1
tion is COOEt > COOMe > CN, while compounds having R = ACl
and R = ACOOMe (Compound 9h) have proved as most effective
2
members against for cancer cell lines A549 and Hep G2 and the
1 3 3
activity in deceasing order for R substitution is Cl > H > CH > OCH
and for substitution is COOMe > COOEt > CN. Moreover,
R
2
reviewing and comparing the activity data, it is worthy to mention
that the anticancer activity and inhibition against EGFR and HER-2
of the target compounds depends not only on the bicyclic
heteroaromatic pharmacophore, but also on the nature of the
substituents.
To gain better understanding on the potency of all compounds
and guide further SAR studies, we proceeded to examine the inter-
action of those with EGFR (PDB code: 1M17) by molecular docking,
which was performed by simulation of compounds into the ATP
binding site in EGFR. The binding energy of all the compounds is
mentioned in Table 2. Of the compounds studied, compound 9i
was nicely bound into the active site of EGFR with minimum bind-
Camptothecin (CPT) is a class of cytotoxic quinoline alkaloid has
been demonstrated to be effective against a broad spectrum of
tumors and inhibits the DNA enzyme topoisomerase I (topo I).
DNA topoisomerase I inhibition progressively became irreversible
with increasing concentration and exposure duration. These
studies also suggested that camptothecin is selectively cytotoxic
to S-phase cells, arrests cells in the G-2 phase and induces frag-
ing energy
D
G
b
= À54.4 kcal/mol. The binding model of compound
3
2,33
9
i and EGFR was depicted in Figures 1 and 2. The amino acid resi-
mentation of chromosomal DNA.
Topoisomerase I and topoiso-
dues which had interaction with EGFR were labeled. In the binding
mode, compound 9i was nicely bound to the ATP binding site of
EGFR through hydrophobic interaction and the binding was stabi-
merase II catalyze the relaxation of supercoiled chromosomal DNA
during DNA replication. The relaxation of DNA by topoisomerase II
involves the transient double strand breakage of DNA, followed by
strand passage and relegation of the DNA strand. In contrast, topo-
isomerase I involve the transient single strand cleavage of duplex
DNA, followed by unwinding and relegation. Topoisomerase I
cleaves DNA at multiple sites, and the highest efficiency cleavage
lized by four hydrogen bonds and two
p–cation interactions.
Among them one hydrogen bond form between N-atom of tetra-
zole ring and ASP813 (distance: 2.1 Å, DHA angle: 137.5°), second
and third form between N-atom of tetrazole ring and THR830 (dis-
tance: 2.5 Å and 2.4 Å, DHA angle: 120.3° and 92.4°) and fourth one
form between N-atom of pyridine ring and LEU694 (distance:
3
4
sites exhibit significant sequence homology.
2
.1 Å, DHA angle: 167.4°). One
p
–cation interaction forms between
Acknowledgments
quinoline nucleus and LYS721 having distance 4.9 Å and second
p–
cation interaction forms between tetrazole nucleus and LYS721
having distance 4.2 Å. From this binding model, it could be con-
This work was supported by Natural Science Foundation of
Jiangsu Province of China (No. BK20130554).
cluded that four hydrogen bond and two
p–cation interactions
are responsible for the effective EGFR inhibitory of compound 9i.
In conclusion, the aim of the present investigation was to design
a new series of 4H-quinoline derivatives by introduction of substi-
tuted tetrazolo[1,5-a]quinoline at the C-4 position and pyridine
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.bmcl.2014.07.094.

4
476
C. B. Sangani et al. / Bioorg. Med. Chem. Lett. 24 (2014) 4472–4476
1
7. Zieba, A.; Sochanik, A.; Szurko, A.; Rams, M.; Mrozek, A.; Cmoch, P. Eur. J. Med.
References and notes
Chem. 2010, 45, 4733.
1
1
8. Gopal, M.; Shenoy, S.; Doddamani, L. S. J. Photochem. Photobiol. B 2003, 72, 69.
9. Kim, Y. H.; Shin, K. J.; Lee, T. G.; Kim, E.; Lee, M. S.; Ryu, S. H. Biochem.
Pharmacol. 2005, 69, 1333.
0. Zhao, Y. L.; Chen, Y. L.; Chang, F. S.; Tzeng, C. C. Eur. J. Med. Chem. 2005, 40, 792.
1. Pannala, M.; Kher, S.; Wilson, N.; Gaudette, J.; Sircar, L.; Zhang, S.; Bakhirev, A.;
Yang, G.; Yuen, P.; Gorcsan, F.; Sakurai, N.; Barbosa, M.; Cheng, J. Bioorg. Med.
Chem. Lett. 2007, 17, 5978.
2. Prachayasittikul, S.; Treeratanapiboon, L.; Ruchirawat, S.; Prachayasittikul, V. J.
Excli. 2009, 8, 121.
3. Nassar, E. J. Am. Sci. 2010, 6, 338.
1
2
3
.
.
.
Gallorini, M.; Cataldi, A.; di Giacomo, V. Biodrugs 2012, 26, 377.
Cicenas, J.; Valius, M. J. Cancer Res. Clin. 2011, 137, 1409.
Slamon, D. J.; Clark, G. M.; Wong, S. G.; Levin, W. J.; Ullrich, A.; McGuire, W. L.
Science 1987, 235, 177.
Slamon, D. J.; Godolphin, W.; Jones, L. A. 1989, 244, 707.
Kolibaba, K. S.; Druker, B. J. Biochim. Biophys. Acta 1997, 1333, 217.
Tateishi, M.; Ishida, T.; Mitsudomi, T.; Kaneko, S.; Sugimachi, K. Cancer Res.
2
2
4
5
6
.
.
.
2
1
990, 50, 7077.
7
8
9
.
.
.
Fleming, T. P.; Saxena, A.; Clark, W. C.; Robertson, J. T.; Oldfield, E. H.; Aaronson,
S. A.; Ali, I. U. Cancer Res. 1992, 52, 4550.
Shin, D. M.; Ro, J. Y.; Hong, W. K.; Hittelamn, W. N. Cancer Res. 1994, 54, 3153–
2
2
4. Maoa, Y.; Zhu, W.; Kong, X.; Wang, Z.; Xie, H.; Ding, J.; Terrett, N. K.; Shen, J.
Bioorg. Med. Chem. 2013, 21, 3090.
5. Sinkkonen, J.; Ovcharenko, V.; Zelenin, K. N.; Bezhan, I. P.; Chakchir, B. A.; Al-
3
159.
2
Ciardiello, F.; Tortola, G. Clin. Cancer Res. 2001, 7, 2958.
Assar, F.; Pihlaja, K. Eur. J. Org. Chem. 2002, 13, 2046.
1
1
0. Jardosh, H. H.; Patel, M. P. Eur. J. Med. Chem. 2013, 65, 348.
1. Thomas, K. D.; Adhikari, A. V.; Telkar, S.; Chowdhury, I. H.; Mahmoode, R.; Pal,
N. K.; Rowd, G.; Sumesh, E. Eur. J. Med. Chem. 2011, 46, 5283.
2. Starcevic, K.; Pesic, D.; Toplak, A.; Landek, G.; Alihodzic, S.; Herreros, E.; Ferrer,
S.; Spaventi, R.; Peric, M. Eur. J. Med. Chem. 2012, 49, 365.
3. Leatham, P. A.; Bird, H. A.; Wright, V.; Seymour, D.; Gordon, A. Eur. J. Rheumatol.
Inflammation 1983, 6, 209.
2
2
2
6. Jain, R. P.; Vederas, J. C. Bioorg. Med. Chem. Lett. 2004, 14, 3655.
7. Kumar, A.; Gupta, M. K.; Kumar, M. Green Chem. 2012, 14, 290.
8. Sangani, C. B.; Makawana, J. A.; Zhang, X.; Teraiya, S. B.; Lin, L.; Zhu, H.-L. Eur. J.
Med. Chem. 2014, 76, 549.
1
1
2
9. Makawana, J. A.; Sangani, C. B.; Lin, L.; Zhu, H.-L. Bioorg. Med. Chem. Lett. 2014,
2
4, 1734.
3
3
3
3
3
0. Sangani, C. B.; Jardosh, H. H.; Patel, M. P.; Patel, R. G. Med. Chem. Res. 2013, 22, 3035.
1. Mungra, D. C.; Patel, M. P.; Patel, R. G. ARKIVOC 2009, xiv, 64.
2. Wall, M. E.; Besterman, J. M. J. Med. Chem. 1993, 36, 2689.
3. Redinbo, M. R.; Kuhn, P.; Champoux, J. J.; Hol, W. G. J. Science 1998, 279, 1505.
4. Staker, B. L.; Burgin, A. B.; Stewart, L. Proc. Natl. Acad. Sci. U.S.A. 2002, 99, 15387.
1
1
4. Kathrotiya, H. G.; Patel, M. P. Eur. J. Med. Chem. 2013, 63, 675.
5. Muruganantham, N.; Sivakumar, R.; Anbalagan, N.; Gunasekaran, V.; Leonard, J.
T. Biol. Pharm. Bull. 2004, 27, 1683.
1
6. Maguire, M. P.; Sheets, K. R.; McVety, K.; Spada, A. P.; Zilberstein, A. J. Med.
Chem. 1994, 37, 2129.