Synthesis, single crystal and antitumor activities of benzimidazole- quinazoline hybrids

Article abstract of DOI:10.1016/j.bmcl.2013.03.107

A series of novel regioisomeric hybrids of quinazoline/benzimidazole viz. (3-allyl-2-methyl-3H-benzimidazol-5-yl)-(2-substituted-quinazolin-4-yl)-amine and (1-allyl-2-methyl-1H-benzimidazol-5-yl)-(2-substituted-quinazolin-4-yl)- amine of biological interest were synthesized. All the synthesized compounds were well characterized by ¹H and ¹³C NMR as well as mass spectroscopy. The newly synthesized compounds were screened for in vitro antitumor activities against 60 tumor cell lines panel assay. A significant inhibition for cancer cells were observed with compound 9 and also more active against known drug 5-fluorouracil (5-FU) in some tumor cell lines. Compound 9 displayed appreciable anticancer activity against leukemia, colon, melanoma, renal and breast cancer cell lines.

Full text of DOI:10.1016/j.bmcl.2013.03.107

Accepted Manuscript
Synthesis, single crystal and antitumor activities of benzimidazole- quinazoline
hybrids
Alka Sharma, Vijay Luxami, Kamaldeep Paul
PII:
S0960-894X(13)00435-6
DOI:
http://dx.doi.org/10.1016/j.bmcl.2013.03.107
BMCL 20343
Reference:
To appear in:
Bioorganic & Medicinal Chemistry Letters
Received Date:
Revised Date:
Accepted Date:
11 February 2013
16 March 2013
26 March 2013
Please cite this article as: Sharma, A., Luxami, V., Paul, K., Synthesis, single crystal and antitumor activities of
benzimidazole- quinazoline hybrids, Bioorganic & Medicinal Chemistry Letters (2013), doi: http://dx.doi.org/
10.1016/j.bmcl.2013.03.107
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Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com
Synthesis, single crystal and antitumor activities of benzimidazole- quinazoline
hybrids
Alka Sharma, Vijay Luxami, Kamaldeep Paul
School of Chemistry and Biochemistry, Thapar University, Patiala-147004 INDIA
ARTICLE INFO
ABSTRACT
Article history:
Received
Revised
Accepted
Available online
A series of novel regioisomeric hybrids of quinazoline/benzimidazole viz. (3-allyl-2-methyl-3H-
benzimidazol-5-yl)-(2-substituted-quinazolin-4-yl)-amine
and
(1-allyl-2-methyl-1H-
interest were
benzimidazol-5-yl)-(2-substituted-quinazolin-4-yl)-amine of
biological
synthesized. All the synthesized compounds were well characterized by 1H and 13C NMR as well
as mass spectroscopy. The newly synthesized compounds were screened for in vitro antitumor
activities against 60 tumor cell lines panel assay. A significant inhibition for cancer cells were
observed with compound 9 and also more active against known drug 5-fluorouracil (5-FU) in
some tumor cell lines. Compound 9 displayed appreciable anticancer activity against leukemia,
colon, melanoma, renal and breast cancer cell lines.
Keywords:
Cancer
Quinazoline
Benzimidazole
Regioisomers
Antitumor activity
Docking
The development of new anti-cancer therapeutic tools has
advanced greatly in the past decade; thus approaches for the
treatment of cancer have moved towards targeting the specific
molecular alterations that occur in tumor cells. This approach has
been concentrated on the development of both small molecules
and biological agents that have shown remarkable clinical
activity without toxicity associated with conventional
chemotherapy.1 Many of chemotherapeutics currently used in
cancer therapy are agents which inhibit tumor growth by
inhibiting the replication and transcription of DNA. The practice
of chemotherapy of cancer suffers from various drawbacks viz.
the participation of a number of enzymes like ribonucletides
reductase (RNR), topoisomerase I (Topo I) and topoisomerase II
(Topo II) etc. at different stages of development of cancer,2
survival of cancer cells even under anaerobic conditions,3 and
ultimately the problem of multidrug resistance4 developed in the
cancerous cells towards chemotherapeutic agents. The wide
occurrence of the heterocycles in bioactive natural products made
them important synthetic targets. Fused pyrimidines have drawn
the attention of medicinal chemists as chemotherapeutic agents,
where several member of this class has earned valued places in
chemotherapy as effective agents.5 Quinazoline derivatives have
attracted attention due to their broad range of pharmacological
activities, which include antifungal,6 antimalarial,7 anti-
inflammatory,8
anticonvulsant,9
antibacterial,10
anti-
hypertensive11 and anticancer.12,13 Several of these compounds
exhibited dihydrofolate reductase and tyrosine kinase14 inhibitors
such as erlotinib, gefitinib, caneratinib, vandetanib and lapatinib
(Chart 1). Some quinazoline derivatives interact with tubulin15
and interfere with its polymerization, others act by modulating
aurora kinase activity16 or have an effect in critical phases in the
cell cycle17 or act as apoptosis inducers.18 The reported
significance of such synthons generated the interest to exploit
this valuable structure in the designing and synthesis of new
quinazoline analogue as antitumor agents.
Cl
F
HN
F
O
HN
Cl
O
O
HN
O
N
N
N
O
N
N
O
O
N
NH
N
O
N
O
O
Erlotinib
Gefitinib
Caneratinib
F
F
F
HN
Cl
NH
O
O
N
O
N
N
O
N
S
N
O
Vandetanib
Lapatinib
Chart 1
———
Corresponding author. Tel.: +91-94656-70595; fax: +91-175-236-4498; e-mail: kpaul@thapar.edu (K.Paul)

Benzimidazole, a heteroaromatic organic compound also created
an interest in medicinal and biological properties such as
To achieve the targets, we have synthesized a new series of
regioisomeric hybrids, (3-allyl-2-methyl-3H-benzimidazol-5-yl)-
(2-substituted-quinazolin-4-yl)-amine and (1-allyl-2-methyl-1H-
antitumor,19
antibacterial,20
vasodilator23
antihypertensive,21
and
antiviral24
anti-
inflammatory,22
agents.
benzimidazol-5-yl)-(2-substituted-quinazolin-4-yl)-amine
and
Benzimidazole derivatives are known inhibitors of cyclin
dependent kinase or tyrosine kinase and are useful for inhibiting
cell proliferation for the treatment of cancer.25 Due to structural
similarity of benzimidazole nuclei with some naturally occurring
compounds such as purine, they can easily interact with
biomolecules of the living systems.
In the present investigation, we have combined the structural
artifacts of benzimidazole and quinazoline moieties as hybrid and
substituted them with secondary amines in order to observe the
effect of electron-donor and acceptor nitrogen groups within the
moieties. Introduction of alkyl or allyl groups on benzimidazole
and aryl groups of quinazoline moiety are also known to increase
lipid solubility of polar compounds, a character very much
evaluated for their anticancer activity against 60 tumor cell lines.
The thrust of efforts in the derivatization of such type of
compounds focused mainly on the secondary amines at 2-
position of quinazoline to find out an active antitumor agent with
potentiated activity and selectivity toward cancerous cells.
Scheme 1 and 2 outlines the synthetic pathways to obtain
compounds 4a-b and 8-13 respectively. Treatment of o-
o
phenylenediamine with acetic acid at 100 C for 24 hrs followed
by nitration with equal amounts nitric acid and sulfuric acid at 0
oC for 5 hrs to obtain 2-methyl-5-nitro-1H-benzimidazole (2)26
with 80% yield. Treatment of compound 2 with allyl bromide in
the presence of sodium hydride and THF at room temperature for
8 hrs got a mixture of 1-allyl-2-methyl-5-nitro-1H-benzimidazole
(3a) and 1-allyl-2-methyl-6-nitro-1H-benzimidazole (3b).
Reduction of 3a and 3b with stannous chloride and 2N HCl at
110 oC for 7 hrs afforded regioisomeric 3-allyl-2-methyl-3H-
needed for the activity (Fig. 1).
H- Acceptor
N
H-donor
CH3
o
benzimidazol-5-ylamine (4a) with 65% yield (mp = 137-139 C)
N
NH
and 1-allyl-2-methyl-1H-benzimidazole-5-ylamine (4b) with
o
N
Hydrophobic
region
25% yield (mp = 137-139 C) (Scheme 1). Appearance of 2H
Lipophillicity
enhancer
1
N
NR1R2
broad singlet at δ 3.56 and 3.74 (exchangeable with D2O) in H
NMR spectra and two NH2 stretchings at 3380, 3270 cm-1 and
3380, 3272 cm-1 in IR spectra confirmed the structures of 4a and
4b respectively.
H- Acceptor / binding region
Figure 1. Proposed hypothetic model for hybrid compounds
N
N
CH3
CH3
N
(iv)
O2N
N
H2N
(iii)
(iii)
3a
4a
4b
4
7
3
O2N
N
NH2
NH2
(ii)
(i)
N
5
CH3
CH3
2
1
N
H
6
N
H
N
N
N
N
2
(iv)
1
CH3
CH3
Reaction Conditions : (i) CH3COOH, 100 oC; (ii) H2SO4, HNO3, 0 oC;
(iii) NaH, allyl bromide, THF, rt;
O2N
H2N
3b
(iv) SnCl4.2H2O, 2N HCl, 100 o
C
Scheme 1 Synthetic route for the preparation of compounds 4a and 4b
N
N
CH3
N
CH3
NH
N
NH
(v)
N
N
N
NR1R2
N
Cl
7a
(iii)
O
Cl
N
8-11
NR1R2
=
8 Morpholin-4-yl
9 Pyrrolidin-1-yl
10 Piperidin-1-yl
NH2
(ii)
(i)
NH
N
N
H
O
COOH
Cl
11 4-Methylpiperazine-1-yl
6
5
(iv)
N
N
N
CH3
(v)
CH3
N
NH
NH
Reaction Conditions : (i) NH2CONH2, 160 oC;
(ii) POCl3, TEA, reflux;
(iii) 4a, IPA, rt;
N
N
NR1R2
12-13
N
Cl
N
(iv) 4b, IPA, rt;
(v) HNR1R2, IPA, reflux
7b
NR1R2
=
12 Morpholin-4-yl
13 Pyrrolidin-1-yl
Scheme 2 Synthetic route for the preparation of target compounds (8-13)
For target compounds 8-13, 2,4-dichloroquinazoline (6)27 was
treated separately with 4a and 4b in isopropyl alcohol (IPA) at
room temperature for 8-12 hrs afforded (3-allyl-2-methyl-3H-
benzimidazol-5-yl)-(2-chloro-quinazolin-4-yl)-amine (7a) with
92% yield (mp = 210-215 oC) and (1-allyl-2-methyl-1H-
benzimidazol-5-yl)-(2-chloro-quinazolin-4-yl)-amine (7b) with
o
82% yield (mp = 217-220 C) respectively. IR spectra of these
compounds showed NH stretching at 3258 and 3252 cm-1
respectively. Compounds 7a was refluxed with 1.2 equivalents of

morpholine-4-yl in IPA for 7-8 hrs and after column
chromatography gave solid pure compound 8 (Scheme 2). The
presence of 4H singlet at 3.88 (O-morCH2), 4H triplet at 3.76
(N-morCH2) in 1H NMR spectrum and signals at 65.7 (O-
morCH2), 46.5 (N-morCH2) in 13C NMR spectrum confirmed the
synthesis of 8.
109.5o). The structure of the compound 12 shown in Fig. 3 is
more likely on the basis of standard bond distances and angles.
Similarly, compounds 7a and 7b were further reacted with
secondary amines at the same reaction conditions gave pure
compounds 9-11 and 12-13 respectively.
Structures of all novel compounds were similarly confirmed by
NMR and mass spectroscopic techniques (supplementary
material). Complete and unambiguous assignments for all 1H and
13C resonances could be achieved on the basis of chemical shift
considerations, coupling information and NOE difference
spectra. Discrimination between 8-11 and 12-13 were achieved
by considering 2D NOE difference experiments (positive NOEs
on signals of N-CH2 protons due to the allyl chain and singlet of
aromatic ring of benzimidazole with compounds 8-11, and
positive NOE’s on signal of N-CH2 protons due to the allyl chain
and doublet of aromatic ring of benzimidazole and negative NOE
with singlet of compounds 12-13 as shown in Fig. 2) and energy
minimized structures (allyl group approaching towards the
singlet of aromatic ring of benzimidazole in 8 and allyl group is
near to doublet of aromatic ring of benzimidazole in 12).
Figure 3. ORTEP diagram of compound 12 (CCDC 928250)
The benzimidazole ring is deviated from the planar quinazoline
by 19.9o. The bond length of two C-N bonds linking between
benzimidazole and quinazoline are differ, with the short C16-N3
[1.359 (4) Å] bond having a double-bond character compared
with the longer N3-C8 [1.419 (4) Å] on benzimidazole side. It is
indicated that the two carbon atom (C16 and C8) in the molecule
occupy anti-positions relative to the mean plane of the ring
system. This anti-position of both carbon atoms in each molecule
is one of the reason which makes the two rings are non planar.
The crystal structure revealed that conformation morpholine was
approaching to the benzimidazole moiety. The bond length of
N1-C1 [1.314 (5)] of benzimidazole ring is shorter having double
bond character than that longer bond length of C1-N2 [1.369 (5)]
indicate the presence of allyl group at N2 position and
quinazoline attached at the 5-position of benzimidazole (C8).
Table 1 Summary of crystal data, data collection and structure
refinement for compound 12
Moreover, the structure of compound 12 was confirmed by
measuring X-ray crystallography.28 In the crystal structure of the
compound, it crystallizes with Z = 4 in the space group P21/c
(Table 1). The molecular solid state structure and numbering
system is indicated in Fig. 3. Molecule presents certain
NOE
H
H
A. Crystal data
Empirical formula
Formula weight
Crystal color, habit
Crystal dimensions
Crystal system
H
H
H
H
N
N
C23H24N6O
400.48
H
N
N
CH3
CH3
NH
H
NH
Colorless, Crystals
0.23 x 0.18 x 0.13 mm
Monoclinic
a = 6.3175(2) Å
b = 23.8231(6) Å
c = 14.1809(4) Å
α = 90.0o
H
H
N
N
NOE
N
NR1R2
N
NR1R2
Lattice parameters
8-11
12-13
β = 98.004(3)o
γ = 90.0o, V = 2113.47(10) Å3
P21/c
Space group
Z value
4
Dcalc
F (000)
1.259 Mg/m^3
848
µ (Mo Ka)
0.081mm-1
Mo Ka radiation, λ
T
0.7107 cm-1
150(2) K
B. Data collection and refinement
Diffractometer
8
12
Crystalispro, Agilent Technology
CCD
Direct Methods
MoKα (λ = 0.7107 A)
Graphite monochromated
Fine-focus sealed tube
32.267o
Figure 2. 2D NOEs 1H, 1H correlations used for structural
assignment of compounds 8-11, 12-13 (upper), energy
minimization of 8 and 12 (lower)
Structure Solution
Radiation
disorder in the terminal allyl group. Thus there is some ambiguity
in the atomic positions of the allyl group. These disorders are
expected due to the conformational flexibility of the allyl
fragment. The six membered morpholine ring is positioned
planar to the quinazoline ring that exists in chair conformation.
Atom system C13-O1-C12 is in regular tetrahedron sp3 angle of
109.5o. Atom system C14-N6-C11 having some angle strain,
deviated by 4.1o from the ideal value (angle strain is calculated as
the difference between internal angle and the ideal sp3 angle of
Radiation source
2θmax
No. of reflections measured
Total: 16020
Unique : 3720 (Rint = 0.0278)
Semi-emipirical from equivalents
0.9895 and 0.9815
Absorption Corrections
Max. and min. transmission
Refinement Method
Data/restraints/parameters
Final R indices [I>2sigma (I)]
R indices (all data)
Full-matrix least-square on Fo2
3720/29/292
R1 = 0.0530, wR2 = 0.1472
R1 = 0.0635, wR2 = 0.1577
1.026
Goodness of fit on F 2

Extinction coefficient
Largest diff. peak and hole
0.011(3)
Preliminary in-vitro antitumor screening revealed that only
compounds 8 and 9 showed significant growth inhibition (more
than 60%) for most of the cancer cell lines. On the contrary the
percentage inhibition of compounds 7a-b and 11-13 did not reach
50%. This shows that the presence of secondary amine
(morpholine or pyrrolidine) is essential in place of chloro at 2-
position of quinazoline for activity of compounds.
Regarding the activity toward individual cell lines; all
compounds showed selective potency toward renal cancer cells
A498 with GI values of 44.5%, 31.5%, 41.1%, 28.5%, 20.7%,
and 27.6% of respective compounds 7a, 7b, 8, 9, 12 and 13.
Leukemia cancer cells HL-60 (TB) proved to be selective
sensitive to 8 with GI value of 61.9%. Compound 9 showed
0.302 and -0.345 eA-3
Seven out of eight synthesized compounds (7a-b, 8-9, 11-13)
(Table 2) were subjected to the National Cancer Institute (NCI),
Bethesda, Maryland, USA on the basis of degree of structure
variation and computer modeling techniques for disease-oriented
human cell lines screening assay for their in-vitro antitumor
activities.29-31 A single dose (10 µM) of the test compounds were
used in the full NCI 60 cell lines panel assay which includes nine
tumor subpanels namely; leukemia, non-small cell lung, colon,
CNS, melanoma, ovarian, renal, prostate and breast cancer cells.
The data reported as mean-graph of the percent growth of the
treated cells and presented as percentage growth inhibition (GI
%).
Table 2 The percentage growth inhibition (GI%) of the selected compounds over the full panel of tumor cell lines
Cell Line Type
Leukemia
Cell Line Name
CCRF-CEM
HL-60(TB)
K-562
7a
nt
7b
nt
8
nt
9
11
31.5
--
12
nt
13.5
--
--
13.4
-
13
nt
5-FU
57.1
Nt
47.9
42.3
43.1
41.4
24.8
34.2
58.4
47.8
50.6
69.5
39.0
59.5
13.0
58.0
40.2
L
15.9
25.2
21.3
24.7
--
--
11.5
98.0
50.0
45.0
94.2
25.4
--
--
61.9
35.6
nt
21.3
--
37.8
43.1
28.5
nt
14.9
--
MOLT-4
RPMI-8226
SR
22.3
--
nt
12.2
11.0
10.1
--
--
Non-Small Cell Lung Cancer
A549/ATCC
EKVX
18.5
--
--
11.8
--
--
--
--
--
-
17.2
--
nt
HOP-62
--
--
--
11.3
42.4
13.6
19.2
--
--
HOP-92
--
--
--
18.6
--
15.5
22.0
--
NCI-H226
NCI-H23
NCI-H322M
NCI-H460
NCI-H522
COLO 205
HCC-2998
HCT-116
HCT-15
--
17.8
--
--
--
--
--
--
--
--
--
--
--
--
--
--
--
--
--
--
--
--
--
nt
--
--
--
--
--
--
--
--
--
--
-
--
--
11.3
--
--
--
--
--
--
--
--
18.7
--
--
--
--
--
--
--
--
Colon Cancer
--
--
--
--
23.6
--
nt
--
--
--
--
76.6
80.3
20.6
94.3
29.9
24.9
13.1
16.3
--
17.8
26.5
27.1
40.7
50.1
59.0
69.1
L
--
--
--
33.0
10.1
42.6
20.5
--
--
--
--
--
--
HT29
--
--
34.7
11.9
--
--
KM12
--
--
--
SW-620
--
--
--
CNS Cancer
Melanoma
SF-268
10.1
15.2
--
--
--
--
--
SF-295
10.3
--
--
--
--
SF-539
--
23.5
--
--
65.9
65.9
50.3
30.4
58.2
nt
SNB-19
--
--
--
--
--
SNB-75
--
--
12.6
--
16.3
--
17.6
10.2
18.0
--
--
U251
--
--
--
LOX IMVI
MALME-3M
M14
--
--
--
--
97.5
--
--
nt
--
--
--
--
--
10.3
--
--
--
36.6
95.5
nt
MDA-MB-435
SK-MEL-2
SK-MEL-28
SK-MEL-5
UACC-257
UACC-62
IGROV1
OVCAR-3
OVCAR-4
OVCAR-5
OVCAR-8
NCI/ADR-RES
SK-OV-3
786-0
--
--
--
--
--
--
--
--
--
--
--
--
--
--
19.8
37.6
--
--
--
33.7
19.5
39.7
51.2
47.4
59.4
44.3
NT
--
--
--
18.3
--
--
--
--
--
--
--
10.2
--
--
--
--
--
Ovarian Cancer
--
--
--
--
--
--
--
--
--
--
--
--
--
--
--
20.7
16.5
23.4
--
--
--
--
--
--
-
--
--
20.1
23.6
--
15.9
16.7
--
--
--
--
--
20.7
--
--
--
47.6
77.5
48.7
L
--
10.5
--
--
--
--
--
Renal Cancer
12.2
44.5
--
--
--
24.0
28.5
--
--
11.1
27.6
--
A498
31.5
--
--
41.2
--
39.3
39.4
ACHN
--
CAKI-1
12.8
16.9
11.5
15.0
14.4
10.2

34.3
54.0
66.9
41.3
58.2
35.5
11.5
RXF 393
SN12C
TK-10
UO-31
PC-3
12.5
--
--
--
--
--
47.6
--
--
--
--
--
--
--
--
--
--
--
--
--
--
--
10.3
19.5
--
14.7
11.4
--
31.9
--
34.2
25.9
--
--
10.1
18.2
--
Prostate Cancer
Breast Cancer
18.0
--
11.9
--
DU-145
MCF7
26.2
38.1
--
--
--
14.4
--
--
78.1
nt
MDA-MB-231/ATCC
10.1
14.5
--
22.8
--
--
58.0
L
HS 578T
BT-549
--
--
--
--
13.1
13.1
--
23.3
20.7
20.6
--
--
--
--
--
--
37.8
56.7
nt
--
--
--
T-47D
18.5
16.3
21.3
19.1
11.2
--
22.6
13.3
MDA-MB-468
--
--, GI < 10%; nt, not tested; L, lethal; The showed inhibition percentage are measured at a single concentration of 10 µM.
selectivity toward leukemia cancer cells K-562, MOLT-4, RPMI-
8226 and SR with GI values of 98.0%, 50.0%, 45.0% and 94.2%
respectively, colon cancer cells COLO 205, HCC-2998 and
HT29 with GI values of 76.6%, 80.3% and 94.3% respectively,
melanoma cancer cell LOX IMVI with GI value of 97.5% and
breast cancer cell MDA-MB-231/ATCC with GI value of 58.0%.
Compound 9 showed higher activity than 5-fluorouracil in
leukemia cancer cells (K-562, MOLT-4, RPMI-8226 and SR),
colon cancer cells (HCC-2998, HCT-116 and HT-29) and
melanoma (LOX IMVI and SK-MEL-5). In addition compound
11 showed sensitivity to leukemia cancer cell MOLT-4, non-
small cell lung cancer cell HOP-92 and colon cancer cell HT29
having GI values of 43.1%, 42.4% and 42.6% respectively. From
Table 2, it is revealed that compound 9 is more active towards
numerous cancer cell lines belonging to different tumor
subpanels.
On the basis of these activities, it has been proved that (3-allyl-2-
methyl-3H-benzimidazol-5-yl)-(2-amino-quinazolin-4-yl)-amine
(8-9, 11) are more active antitumor agents than their
regioisomeric analogue (1-allyl-2-methyl-1H-benzimidazol-5-
yl)-(2-amino-quinazolin-4-yl)-amine (12-13). Substitution of
chloro (7a) with secondary amines such as morpholin-4-yl (8)
and 4-methylpiperzin-1-yl (11) did not improve their activity
much. But substitution of chloro (7a) with pyrrolidin-1-yl (9)
proved the remarkably activity as antitumor agents. Similarly
compound 7b showed activity in some of the tumor cell lines but
substitution at 2-position of quinazoline with morpholin-4-yl (12)
and pyrrolidin-1-yl (13) decreased its potency. Thus, allyl group
of benzimidazole approached towards the secondary amine at 2-
position of quinazoline (9) showed higher activity than on the
opposite side (13).
Where, P - partition coefficient; log P - logarithm of the partition
coefficient.
amines at 2-position of quinazoline moiety resulted in increase of
log P value (lipophilicity). From Table 3, it is clear that
lipophilicity is a crucial factor for the activity amongst the
synthesized compounds in this series as compound 9 has higher
log P value which corresponds to higher antitumor activity.
In vitro evaluation of compound
9 exhibited remarkable
anticancer activity towards leukemia cancer cell lines as shown in
Table 2. So we have performed docking experiments with
ribonucleotide reductase (RNR), topoisomerase I (Topo I) and
topoisomerase II (Topo II) that possesses potent
chemotherapeutic efficacy against leukemia.33 We have carried
out docking34 of most active compound 9 in the active site
ribonucleotide reductase (enzyme responsible for DNA
replication, pdb ID 4R1R), topoisomerase I (pdb ID 1A36) and
topoisomerase II (pdb ID 1BJT). Docking of compound 9 in the
active site of RNR showed H-bond interactions between N atom
of quinazoline moiety with F1023 amino acid residue of active
site, N atom of pyrrolidine moiety with F1023 and T1025 amino
acid residue and NH group with Q294 amino acid residue (Fig.
4). Similarly compound 9 was also docked with active site of
topoisomerase
I and II (another enzyme involved in the
propagation of cancer, synthesis of raw material for replication of
DNA). Here also this compound interacted with the active site of
amino acids through number of H-bonds (supplementary
material).
We have observed the compliance of compounds by determining
32
the lipophilicity via “Shake Flask” method
(supplementary
information). Within the series of two chloro isomers, 7a showed
higher log P value than 7b. Introduction of secondary substituted
Table 3 Experimental determined lipophilicity
Compounds
P
log P
2.10
1.17
2.81
2.90
2.72
1.03
2.49
2.51
7a
7b
8
125.9
14.72
648.45
797.24
524.8
10.82
309.35
324.50
9
10
11
12
13

Figure 4. Compound 9 docked in the active site of RNR. Hs' are omitted for
clarity. Carbon atoms of compound 9 are given different color.
Abdel-Aziz, N. I.; EI-Sayed, M. A.-A.; Aleisa, A. M.; Sayad-Ahmed, M.
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M. N.; Patel, H. M.; Bhardwaj, V.; Chauhan, A. Eur. J. Med. Chem.
2011, 46, 2327.
Therefore, docking of compound 9 in the active site of these
enzymes indicated the probable mode of action of this compound
for anticancer activities. Remarkable, such correlations between
the experimental data, lipophilicity and docking studies are
useful for refining the structure of the molecules and improving
their efficacies.
13. (a) Chandrika, P. M.; Yakaiah, T.; Rao, A. R. R.; Narsaiah, B.; Reddy, N.
C.; Srindar, V.; Rao, J. V. Eur. J. Med. Chem. 2008, 43, 846. (b) Al-
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In conclusion, we have reported the synthesis of novel antitumor
molecules. Here, we have separated two regioisomers, identified
by various spectroscopic techniques and evaluated for 60 tumor
cell lines for anticancer activity. Some of these compounds have
shown remarkable antitumor activity. Compound 9 showed broad
spectrum antitumor agents showing effectiveness toward
numerous cell lines belonging to different tumor subpanels. Thus,
the introduction of pyrrolidine moiety is preferred over chloro
and other secondary amines at 2-position of quinazoline.
Molecular docking also showed H-bonding interaction in the
active site of RNR, Topo I and Topo II that also supported its
activity. These hybrids of benzimidazole and quinazoline
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Further optimizations of antitumor profiling of these series are
currently ongoing in lab.
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We thank to Council of Scientific and Industrial Research
(02(0034)/11/EMR-II) for the research grant. We also thank
Punjab University, Chandigarh for recording NMR and mass
spectra and Dr. Shaikh M. Mobin IIT Indore for X-ray
crystallography,. NCI, USA is gratefully acknowledged for
investigating antitumor activities.
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34. Compounds were constructed and docked with builder toolkit of the
software package ArgusLab 4.0.1 (www.arguslab.com).

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Synthesis, single crystal and antitumor actiLveitaiveesthoifs abreeanbzlainmk ifdoraazbosltrea-ct info.
quinazoline hybrids
Alka Sharma, Vijay Luxami, Kamaldeep Paul
School of Chemistry and Biochemistry, Thapar University, Patiala-147004, INDIA
N
6 steps
NH2
NH2
CH3
HN
N
N
N
NR1R2