Synthesis and characterization of 2-substituted benzimidazoles and their evaluation as anticancer agent

Article abstract of DOI:10.1016/j.saa.2015.01.106

In this work, we report a series of benzimidazole derivatives synthesized from benzene-1,2-diamine and aryl-aldehydes at room temperature. The synthesized compounds have been characterized on the basis of elemental analysis and various spectroscopic studi

Full text of DOI:10.1016/j.saa.2015.01.106

Accepted Manuscript
Synthesis and Characterization of 2-substituted benzimidazoles and their eval-
uation as anticancer agent
Mohammad Azam, Azmat Ali Khan, Saud I. Al-Resayes, Mohammad Shahidul
Islam, Ajit Kumar Saxena, Sourabh Dwivedi, Javed Musarrat, Agata
Trzesowska-Kruszynska, Rafal Kruszynski
PII:
S1386-1425(15)00127-4
http://dx.doi.org/10.1016/j.saa.2015.01.106
SAA 13274
DOI:
Reference:
To appear in:
Spectrochimica Acta Part A: Molecular and Biomo-
lecular Spectroscopy
Received Date:
Revised Date:
Accepted Date:
2 September 2014
4 January 2015
30 January 2015
Please cite this article as: M. Azam, A.A. Khan, S.I. Al-Resayes, M.S. Islam, A.K. Saxena, S. Dwivedi, J. Musarrat,
A. Trzesowska-Kruszynska, R. Kruszynski, Synthesis and Characterization of 2-substituted benzimidazoles and
their evaluation as anticancer agent, Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy (2015),
doi: http://dx.doi.org/10.1016/j.saa.2015.01.106
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Synthesis
and
Characterization
of
2-substituted
benzimidazoles and their evaluation as anticancer agent
a
b
a
Mohammad Azam,* Azmat Ali Khan
,
Saud I. Al-Resayes, Mohammad Shahidul
a
c
d
d
Islam, Ajit Kumar Saxena
Kruszynska , Rafal Kruszynski
,
Sourabh Dwivedi , Javed Musarrat Agata Trzesowska-
,
e
e
a
Department of Chemistry, King Saud University, P. O. Box 2455, Riyadh 11451, KSA
Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh-11451,
KSA
b
c
Cancer Pharmacology Division, Indian Institute of Integrative Medicine, CSIR, Canal Road, Jammu-
80001, India
1
d
Department of Ag. Microbiology, Faculty of Ag. Sciences, Aligarh Muslim University, Aligarh, India
e
Institute of General and Ecological Chemistry, Technical University of Lodz, Zeromskiego 116, 90-924
Lodz, Poland
For Correspondence: Email: azam_res@yahoo.comTel: +966596441517 Fax: +966-1-
4
675982
1

Abstract:
In this work, we report a series of benzimidazole derivatives synthesized from benzene-
1
,2-diamine and aryl-aldehydes at room temperature. The synthesized compounds have
been characterized on the basis of elemental analysis and various spectroscopic studies
1
13
viz., IR, H- and C- NMR, ESI-MS as well by X-ray single X-ray crystallographic
study. Interaction of these compounds with CT-DNA has been examined with
fluorescence experiments and showed significant binding ability. All the synthesized
compounds have been screened for their antitumor activities against various human
cancer cell lines viz., Human breast adenocarcinoma cell line (MCF-7), Human leukemia
cell line (THP-1), Human prostate cancer cell lines (PC-3) and Adenocarcinomic human
alveolar basal epithelial cell lines (A-549). Interestingly, all the compounds showed
significant anticancer activity.
Keywords: Benzimidazoles; Crystal structure; DNA interactive studies; Anti-proliferative
studies
2

Introduction:
Benzimidazole is a heterocyclic moiety possessing wide spectrum of biological and
clinical applications due to their structural resemblance to the naturally occurring
nucleotides found in living system [1-2]. Moreover, nucleus of benzimidazole is also
found in variety of naturally occurring compounds such as vitamin B12, structurally
similar to purine bases. Therefore, benzimidazole and its derivatives represent one of the
highly biologically active class of compounds possessing various biological activities [3-
7
], viz., antimicrobial [8-11], anti-inflammatory [12-15], antiviral [16], anthelmintic [17],
anti-tumor [18], anticancer [19], antivirus [20], antihistamine [21], antihypertensive [22],
antineoplastic [23], anti-analgesic [24], antiprotozoal [25], anti-hepatitis B virus activity
[
26]. Furthermore, they also exhibit a remarkable activity against several viruses such as
HIV [27], herpes (HSV-1) [28], and RNA influenza [29]. In addition, benzimidazoles
serve as ligands for asymmetric catalysts in various reactions [30]. Therefore, the
synthesis of these benzimidazole-containing compounds has received considerable
attention in diverse areas of chemistry, and a number of synthetic methods have been
developed to uncover a variety of new reagents for their preparation [31-40]. The most
commonly-used synthetic approach typically involve the condensation of o-arylene-
diamines with carbonyl compounds such as aldehydes, carboxylic acids and their
derivatives which often require strongly acidic conditions, sometimes combined with
very high temperature or the use of microwave irradiation [31- 40]. In addition, there are
several reports on benzimidazole synthesis via the reductive cyclization of o-nitroanilines
with aldehydes [41], cyclization of o-nitroaniline derivatives with aryl isothiocyanates
3

[
42, 43], and Baker’s yeast reduction of 2, 4-dinitroacyl anilines [44]. In the last decade,
lot of work has been reported on synthesis of various benzimidazole derivatives and their
biological applications [45]. To add the novelty in the work, herein we successfully
isolated the benzimidazole derivatives in high yield without using any catalyst and
screened the synthesized compounds against number of cell lines viz., human breast
adenocarcinoma cell line (MCF-7), human leukemia cell line (THP-1), human prostate
cancer cell lines (PC-3) and adenocarcinomic human alveolar basal epithelial cell line (A-
5
49) and we got significant results. In addition, we also characterized benzimidazole
derivative 1 by single crystal X-ray diffraction, which has not been reported before.
Experimental:
General remarks
Glassware was oven–dried overnight at 120 ºC before use. Reactions were performed
under an inert atmosphere using an argon filled glove box. All the reactions were
monitored by TLC analysis using Merck Silica Gel 60 F–254 thin layer plates. Column
chromatography was performed on silica gel 100–200 mesh. Benzene-1,2-diamine and
aryl-aldehydes were commercially obtained and used as purchased without further
purification.
Instrumentation: NMR spectra were recorded with a Jeol spectrometer at 400 MHz
1
13
(
H–NMR) and 100 MHz ( C–NMR). The chemical shifts (δ in ppm) were reported
down field from tetramethylsilane (TMS, δ scale) with d -DMSO as resonance referenced
6
as internal standard. Elemental analyses were performed on a Perkin Elmer 2400
Elemental Analyzer. IR spectra were obtained using Perkin Elmer FTIR–800 Model.
Fluorescence measurements were carried out on a Shimadzu spectrofluorimeter model
4

RF-540. Mass spectrometric analysis was conducted by using ESI mode on AGILENT
Technologies 6410–triple quad LC/MS instrument.
General Procedure (GP) for synthesis of 2-phenyl-1H-benzo[d]imidazole derivatives:
To a dried 100 mL round bottom flask were added benzene-1,2-diamine (540 mg, 5
mmol) and aryl-aldehyde (5.0 mmol,) in methanol (15 ml) under argon atmosphere
(
Scheme 1S). Then solution was stirred for 24 h. Progress of the reaction was monitored
by TLC and the solvent was removed under reduced vacuum and the residue was
chromatographed on silica gel column with ethyl acetate/n-hexane (1:1, v/v) to afford the
pure product 1-3.
2
-(2-chlorophenyl)-1H-benzo[d]imidazole, 1
Benzene-1,2-diamine (540 mg, 5.0 mmol) and 2-chloroaldehyde (700 mg, 5.0 mmol) in
methanol (15 mL) were reacted according to GP. The product was purified by column
chromatography on silica gel (40% EtOAc in hexane) yielded 1 (1.1 g, 4.82 mol,
o
–1 1
9
6.46%); m.p. = 232 C; IR (KBr): 3427, 3061, 2882, 1639, 1460, 1242 cm ; H-NMR
DMSO-d , 400 MHz) δ 7.20 (t, J = 8.4 Hz, 2H, ArH), 7.54 (d, J = 8.4 Hz, 1H, ArH),
.66 (d, J = 8.4 Hz, 1H, ArH), 7.76 (d, J = 8.8 Hz, 2H, ArH), 8.09 (d, J = 8.8 Hz, 2H,
(
6
7
1
3
ArH), 12.21 (s, 1H, NH of Indole); C-NMR (DMSO-d6, 100 MHz): δ 112.1, 119.5,
22.8, 123.5, 123.9, 128.9, 129.8, 132.6, 141.7, 150.8; [Anal. Calcd. for C13 Cl
228): C, 68.28; H, 3.97; N, 12.25; Found: C, 68.39; H, 3.99; N, 12.27], ESI: [M+H] m/z
29.68
1
H
9
N
2
+
(
2
2
-(4-bromophenyl)-1H-benzo[d]imidazole 2
5

Benzene-1,2-diamine (540 mg, 5.0 mmol) and 4-bromoaldehyde (920 mg, 5.0 mmol) in
methanol (15 mL) were reacted according to GP. The product was purified by column
chromatography on silica gel (40 % EtOAc in hexane) yielded 2 (1.29 g, 4.74 mol,
o
–1
1
9
4.85%); m.p. = 269 C; IR (KBr): 3417, 1646, 1435, 742, 700, 587cm ; H-NMR
DMSO-d , 400 MHz) δ 7.33 (d, J = 8.0 Hz, 2H, ArH), 7.37 – 7.41 (m, 2H, ArH), 7.45 –
.49 (m, 1H, ArH), 7.67 – 7.71 (m, 1H, ArH), 8.46 (d, J = 8.0 Hz, 2H, ArH), 12.53 (s,
(
6
7
1
1
3
2
1
3
H, NH); C-NMR (DMSO-d6, 100 MHz): δ 114.2, 121.5, 129.7, 130.5, 134.8, 140.9,
52.8; [Anal. Calcd. for C13
H
9
BrN : C, 57.17; H, 3.32; N, 10.26. Found: C, 56.79; H,
2
+
.19; N, 9.87], ESI: [M+H] m/z 274.13
-(4-nitrophenyl)-1H-benzo[d]imidazole 3
Benzene-1,2-diamine (540 mg, 5.0 mmol) and 4-nitroaldehyde (755 mg, 5.0 mmol) in
methanol (15mL) were reacted according to GP. The product was purified by column
chromatography on silica gel (50 % EtOAc in hexane) yielded 3 (1.13 g, 4.72 mol,
o
–1 1
9
4.53%); m.p. = 265 C IR (KBr): 3351, 3057, 2922, 1619, 1493, 1282 cm ; H-NMR
DMSO-d , 400 MHz) δ 7.25 (d, J = 7.6 Hz, 2H, ArH), 7.33–7.37 (m, 2H, ArH), 7.41–
.48 (m, 1H, ArH), 7.59–7.64 (m, 1H, ArH), 8.61 (d, J = 7.6 Hz, 2H, ArH ), 12.28 (s,
(
6
7
1
1
1
3
H, NH of Indole); C-NMR (DMSO-d6, 100 MHz): δ 115.7, 121.8, 124.4, 137.9, 136.2,
41.1, 147.9, 150.2; [Anal. Calcd. for C13
H
9
N
3
O : C, 65.27; H, 3.79; N, 17.56; Found:
2
+
C, 65.9; H, 3.63; N, 1747], ESI: [M+H] m/z 712.22
Crystal structure determination
The colourless elongated (in the crystallographic [001] axis direction) prism shaped
crystal of compound 1 was sealed in glass capillary filled with helium and next it was
mounted on a KM-4-CCD automatic diffractometer equipped with CCD detector, and
6

used for data collection. X-ray intensity data were collected with graphite
monochromated CuK (λ = 1.54178 Å) radiation at temperature 100(1) K and in ω scan
α
mode. The 11 seconds exposure time was used, and reflections inside Ewald sphere were
collected up to θ= 72.3°. The unit cell parameters were determined from 769 strongest
reflections. Details concerning crystal data and refinement are given in Table 1.
Examination of reflections on two reference frames monitored after each 20 frames
measured showed no loss of the intensity during measurement. During the data reduction
Lorentz, polarization and numerical absorption [46] corrections were applied. The
structure was solved by partial structure expansion procedure. All the non-hydrogen
2
atoms were refined anisotropically using full-matrix, least-squares technique on F . All
the hydrogen atoms were found from difference Fourier synthesis after four cycles of
anisotropic refinement, and refined as “riding” on the adjacent atom with geometric
idealisation after each cycle of refinement and with individual isotropic displacement
factors equal 1.2 times the value of equivalent displacement factor of the parent atoms.
The SHELXS97, SHELXL97 and SHELXTL [47] programs were used for all the
calculations. Atomic scattering factors were taken from International Tables for
Crystallography [48]. Selected interatomic bond distances and angles are listed in Table 2
and intermolecular interactions are listed in Table 3.
DNA binding analysis of compound 1, 2 and 3
DNA binding experiments were performed utilizing fluorescence spectrofluorometry.
The purity of calf thymus DNA was confirmed by taking the ratio of the absorbance
values at 260 and 280 nm in tris-EDTA (10 mM, pH 7.0) buffer, which was found to be
1
.8 : 1, indicating that the DNA was sufficiently free of protein and other contaminants.
7

For measurements all the three compounds were dissolved in 2% DMSO. DNA binding
assays of synthesized compounds were carried out in the presence of ethidium bromide.
DNA and ethidium bromide (EtBr) were dissolved in tris-EDTA (10 mM, pH 7.0) buffer
−
1
at concentrations of 4 and 1 µg ml , respectively. The concentration of organic
compounds 1, 2 and 3 were 50 µM. To perform the experiments, DNA was pretreated
with EtBr for 30 min. Then the test solutions were added to this mixture of EtBr–DNA,
and the change in the fluorescence intensity was measured. The fluorescence was
recorded at 485–685 nm after exciting the solution at 478 nm. The slits were set at 5 nm
for excitation and emission. The path length of the sample was 1 cm. To determine the
DNA-binding ability of compounds, fluorescence intensity data were analyzed by the
Stern–Volmer equation [49].
0
F /F = 1+ Ksv[Q]
Where, F and F are the fluorescence intensity with and without the quencher (complex–
0
DNA), Ksv is the Stern–Volmer quenching constant, and [Q] is the concentration of the
quencher.
Method for determination of in-vitro cytotoxicity
-2
All compounds tested were dissolved in DMSO and their stock solution of 2 x 10 M
was prepared. Stock solutions were further diluted with complete growth medium
supplemented with 50 µg/ml gentamycin to obtain test concentration. Various stock
solutions of positive and negative controls were prepared (viz: Adriamycin and paclitaxel
-3
in DMSO = 2 x 10 M; 5-Flurouracil and Mitomycin-C in double distilled water = 2 x
-3
1
0 ). All the cells were maintained in RPMI-1640 medium and DMEM media,
8

supplemented with fetal bovine serum (10%), 100 units/ml penicillin and 100 mg/ml
streptomycin (complete medium). Viability of cells was evaluated by trypan blue
exclusion method immediately before setting up the experiment for cytotoxicity
determination. Cells with >98% viability were used in the assay [50]. Briefly, the cells
4
were seeded into 96 well cell culture plates (1 x 10 cells/100 µl/well) and incubated in
0
CO
2
incubator (37 C, 5% CO
2
, 95% relative humidity) for 24 h. After 24 h, compounds
and positive controls (100 µl/well) were added in quadruplets and the plates were further
incubated in CO incubator for 48 h. Suitable controls were also included in each
2
experiment. After 48 h chilled trichloro acetic acid (50% w/v, 50 ml) was laid gently on
o
top of the medium in all the wells. The plates were incubated at 4 C for one hour to fix
the cells. All the contents of the wells were gently pipetted out and discarded. The plates
were washed five times with distilled water to remove trichloroacetic acid, growth
medium, low molecular weight metabolites and serum proteins. Further, the plates were
air-dried and sulphorhodamine-B (0.4% SRB in 1% acetic acid, 100 µl/well) was added
to each well of the 96 well plates and incubated for 30 min. Excess of the dye was
washed off using 1% acetic acid and the plates were air-dried. Tris-buffer (10 mM, pH
1
0.5, 100 ml/well) was added to each well and plates were shaken on a mechanical stirrer
for 10 min and O.D. was recorded on ELISA reader at 540 nm. Cell growth in control
wells was considered 100% and in turn percent growth inhibition was calculated.
Results and Discussion
Crystal Structure of compound 1
A perspective view of compound 1 is shown in Figure 1S. The compound shows minor
signs of disorder at terminal atoms, what exhibits in slightly prolated anisotropic
displacement ellipsoids of C10, C11 and C12 atoms. All atoms of the compound 1
9

occupy the general positions. The 1H-benzimidazole moiety is close to planarity (the
maximum deviation from the weighted least squares plane calculated thought all respect
non-hydrogen atoms exists for C1 atom and it is equal to 0.022(1) Å), and the planar in
the rage of experimental error fused benzene and imidazole rings are inclined at 1.71(9)°.
The dihedral angle between the weighted least squares planes of 1H-benzimidazole and
chlorophenyl moieties is equal to 39.85(5)°, and it is different from the typical one
existing between substituted, above mentioned, moieties (most populated angle values is
5
° and over of 50% of observed angles falls in the range 0-15°) [51]. On the basis of bond
lengths analysis it can be stated that bonds within the imidazloe ring (Table 2) show
rather delocalised character (mean bond length of typical delocalised N-C bond is 1.336
Å [48]) than single or double character (mean bond length of 1.469 in C-NH systems and
1
.279 Å in Car-C=N-C bond system [48], respectively). The C1-C8 bond (linking the
rings systems) also shows slight shortening (about 0.05 Å) in comparison to purely single
C-C bond. The compound 1 forms one intramolecular and one intermolecular hydrogen
bond (Table 3), which, on the basis of system geometry, can be classified as medium
strength one [52]. These interactions create the S(6) and C(4) unitary graph set motifs of
the lowest degree, and the chain extends along crystallographic [010] axis. Additionally
in the structure can be found the two C—H•••π interactions (Table 3) expanding the
above mentioned chains to the supramolecular layer propagating along crystallographic
(
001) plane. The possibility of the existence of a π•••π interactions was rejected on the
basis of the long dissonance between centroids of the neighbouring delocalised rings (the
shortest one is 4.638(2) Å)
10

DNA Binding property of Benzimadazole compounds 1, 2 and 3
The fluorescence spectroscopy provides insight of the changes taken place in the
microenvironment of DNA molecule on ligand binding. The binding of these compounds
with calf thymus DNA was studied by monitoring the changes in the intrinsic
fluorescence of these compounds at varying concentration of compounds. Figure 1 shows
the representative fluorescence emission spectra of the EtBr-DNA compound. Ethidium
bromide, a polycyclic aromatic dye, is the most widely used fluorescence probe for DNA
structure. EtBr displays very weak fluorescence in aqueous solution. However, in the
presence of DNA, it exhibits intense fluorescence because of intercalation with base pairs
in DNA [53]. The gradual decrease in the fluorescence emission intensity of EtBr-DNA
complex with a conspicuous change in the emission signals occur due to addition of
compounds. The quenching of the compound fluorescence clearly indicated that the
binding of DNA to compounds changed the microenvironment of fluorophore residue.
The fluorescence data revealed the maximum quenching in compound 2 as compared to 1
4
and 3. The KSV value of the compound 1, 2 and 3 were calculated to be 0.8 × 10 , 1.9 ×
4
3
−1
1
0 and 2 × 10 M , respectively. A higher KSV value of compound 2 suggests its
stronger quenching ability than compound 1 and 2 [Fig 2]
In vitro cyctotoxic assay of compounds 1, 2 and 3
In vitro cytotoxic studies of the compounds were carried out on different cancer cell lines
according to the protocol of Skehan et al. [54]. Briefly, the cytotoxic effects were
observed on breast (MCF-7), leukemia (THP-1), prostrate (PC-3) and lungs (A-549)
cancer cell lines. The cytotoxic effects are reported in terms of percent growth inhibition
(
Table 4) and IC50 values (Table 5). All tested compounds showed concentration
11

dependent cytotoxicity against all the four cell lines used for the study. Compound 3 was
least effective and maximum growth inhibition of 51% was observed at the highest
concentration of 100 µM of compound. Compound 1 and 2 showed better growth
inhibitory activity as compared to 3. Compound 1, showed 72-88% and 82-95% growth
inhibition at 50 µM and 100 µM respectively. In comparison, Compound 2 showed 68-
9
3% and 71-96% growth inhibition at 50 µM and 100 µM respectively. Interestingly,
Compound 2 also showed 66% growth inhibition at 10 µM. Thus, the present study
indicates that compounds 1 and 2 have better anticancer activity as compared to
compound 3. Compounds 1 and 2 are more or less equally active but still compound 2 is
marginally better than compound 1 in its anticancer activity.
IC50 values are well coordinated with the observed values for percent growth inhibition.
Compound 2 showed lower IC50 values (15µM) as compared to compound 3 and 1,
indicating compound 2 have higher affinity against cancer cell lines and more potent anti-
cancer agent in comparison to compound 3 and 1 (Table 5). The difference in their
activity is due to their different chemical structure.
Supplementary Data
Tables of crystal data and structure refinement, anisotropic displacement coefficients,
atomic coordinates and equivalent isotropic displacement parameters for non-hydrogen
atoms, H-atom coordinates and isotropic displacement parameters, bond lengths and
interbond angles have been deposited with the Cambridge Crystallographic Data Centre
under No. CCDC960494.
12

Acknowledgements:
The authors would like to extend their sincere appreciation to the Deanship of Scientific
Research at King Saud University for funding of this research through the Research
Group Project No. RGP-212.
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18

EtBR + DNA
EtBr + DNA+ 3
EtBr + DNA+ 1
EtBr + DNA+ 2
EtBr
4
3
2
1
00
00
00
00
0
560
580
600
620
640
Wavelength (nm)
Figure 1: Fluorescence emission spectra of ethidium bromide (EB) bound to DNA in the
absence and presence of compound 1, 2 and 3.
19

Compound 1
3.0
2.5
2.0
1.5
1.0
0.5
3.0
2.5
2.0
1.5
1.0
Compound 2
0
10
20
30
40
50
0.5
0
10
20
30
40
50
DNA
DNA
(
a)
(b)
3
Compound 3
2
1
0
0
10
20
30
40
50
DNA (µM)
(
c)
Figure 2: Stern-Volmer plot of compound 1, 2 and 3 fluorescence quenching
data.
20

Table 1. Crystal and structure refinement data of the compound 1
Compound
1
Empirical formula
C H ClN
2
1
3
9
Formula weight
228.67
Crystal system, space group
Unit cell dimensions [Å, °]
orthorhombic, Pbca (No. 61)
a = 7.0197(1)
b = 9.9261(1)
c = 31.8686(4)
3
Volume [Å ]
2220.55(5)
8, 1.368
3
Z, Calculated density [Mg/m ]
-1
Absorption coefficient [mm ]
2.796
F(000)
944
Crystal size [mm]
0.22, 0.17, 0.08
2.77 to 72.30
θ range for data collection [°]
Index ranges
-8≤h≤8, -12≤k≤11, -39≤1≤38
23186 / 2194 [R(int) = 0.0246]
100.0 (to θ = 67°)
Reflections collected / unique
Completeness [%]
Min. and max. transmission
Data / restraints / parameters
0.607 and 0.795
2194 / 0 / 145
2
Goodness-of-fit on F
1.064
Final R indices [I>2σ(I)]
R1 = 0.0368, wR2 = 0.0923
R indices (all data)
R1 = 0.0369, wR2 = 0.0923
-3
Largest diff. peak and hole [e•Å ]
0.300, -0.448
Table 2. Selected structural data of the compound 1 [Å, °].
21

_
___________________________________________________________________________
N1—C1
N1—C2
N2—C1
N2—C3
C1—C8
1.3584(17)
1.3764(17)
1.3252(17)
1.3855(17)
1.4752(18)
C1—N1—C2
N2—C1—N1
C1—N2—C3
106.97(10)
112.87(11)
105.05(11)
N1—C1—C8—C9
N2—C1—C8—C9
N1—C1—C8—C13
N2—C1—C8—C13
-41.2(2).
144.37(14)
138.28(14)
-36.18(19)
_
___________________________________________________________________________
Table 3. Hydrogen bonds geometry of the compound 1 [Å, °]. Cg1, Cg2 – the centroids of the ring
composed from the C1/C2/C3/N1/N2 and C2/C3/C4/C5/C6/C7 atoms, respectively.
_
___________________________________________________________________________
D—H•••A
_
d(D-H)
d(H•••A) d(D•••A)
<(DHA)
___________________________________________________________________________
N1—H1N•••Cl1i
N1—H1N•••N2
C6—H6•••Cg2
0.88
0.88
0.95
2.773.0940(11)
1.952.8006(15)
2.88 3.6387(16)
103.1
162.9
138.1
ii
iii
C12—H12•••Cg1
_
0.95
2.973.5574(16)
121.6
___________________________________________________________________________
Symmetry transformations used to generate equivalent atoms: (i) -x+1/2, y+1/2, z; (ii) x+1/2, y, -z+1/2; (iii)
x-1, y, z.
Table 4: Percent Growth Inhibitory rates of free ligand, L and complexes 1 and 2 against
cancer cell line
22

Tissue
Breast
Leukemia
THP-1
Prostate
PC-3
Lung
Cell line type
MCF-7
A-549
Conc.
(µM)
CCL Codes
M-4460
Inst. Codes
3
% Growth Inhibition
10
38
41
51
37
72
94
36
93
96
72
-
25
33
55
11
88
95
39
68
71
-
19
28
51
32
73
82
42
60
81
-
15
35
55
36
73
85
30
70
89
-
5
0
1
00
M-4461
M-4462
1
2
10
5
0
1
00
10
5
0
1
00
Adriamycin
Paclitaxel
1
1
1
-
-
65
-
Mitomycin
-
-
61
-
5
-Fluorouracil
20
-
67
-
Table 5: IC50 values of synthesized compounds on various cell lines
23

IC50 (µM)
Cell lines
Compound
MCF-7
38 ± 2
35 ± 2
85 ± 1
THP-1
43 ± 3
48 ± 2
86 ± 2
PC-3
45 ± 1
46 ± 1
96 ± 1
A-549
44 ± 1
43 ± 2
84 ± 1
1
2
3
24

25

1
2
3
4
) Synthesis of benzimidazoles derivatives
) X-Ray crystal structure
) DNA binding studies
) Anticancer activities
26