Palladium(II) complexes as biologically potent metallo-drugs: Synthesis, spectral characterization, DNA interaction studies and antibacterial activity

Article abstract of DOI:10.1016/j.saa.2013.01.013

Four novel mononuclear Pd(II) complexes have been synthesized with the biologically active Schiff base ligands (L₁-L₄) derived from 3-amino-2-methyl-4(3H)-quinazolinone. The structure of the complexes has been proposed by elemental a

Full text of DOI:10.1016/j.saa.2013.01.013

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 107 (2013) 108–116
Contents lists available at SciVerse ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Palladium(II) complexes as biologically potent metallo-drugs: Synthesis, spectral
characterization, DNA interaction studies and antibacterial activity
c
b
c
Kollur Shiva Prasad a, , Linganna Shiva Kumar , Shivamallu Chandan , R.M. Naveen Kumar ,
⇑
Hosakere D. Revanasiddappa c
a Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012, Karnataka, India
b Department of Biotechnology, University of Mysore, Manasagangotri, Mysore 570 006, Karnataka, India
c Department of Chemistry, University of Mysore, Manasagangotri, Mysore 570 006, Karnataka, India
g r a p h i c a l a b s t r a c t
h i g h l i g h t s
New Pd(II)-Schiff base complexes were synthesizes and characterized using spectral techniques. DNA
interaction studies were performed using the synthesized Pd(II) complexes.
"
We synthesized four biologically
potent palladium(II) complexes.
The structures of synthesized
complex were confirmed by spectral
techniques.
"
"
"
DNA binding studies show that
complexes are avid binders to
double helix CT-DNA.
Palladium(II) complexes were able
to cleave the supercoiled plasmid
DNA even in the absence of an
oxidant.
a r t i c l e i n f o
a b s t r a c t
Article history:
Four novel mononuclear Pd(II) complexes have been synthesized with the biologically active Schiff base
ligands (L1–L4) derived from 3-amino-2-methyl-4(3H)-quinazolinone. The structure of the complexes has
been proposed by elemental analysis, molar conductance, IR, 1H NMR, mass, UV–Vis spectrometric and
thermal studies. The investigation of interaction of the complexes with calf thymus DNA (CT-DNA) has
been performed with absorption and fluorescence spectroscopic studies. The nuclease activity was done
using pUC19 supercoiled DNA by gel-electrophoresis. All the ligands and their Pd(II) complexes have also
been screened for their antibacterial activity by discolor diffusion technique.
Received 15 September 2012
Received in revised form 5 January 2013
Accepted 10 January 2013
Available online 23 January 2013
Keywords:
Palladium(II) complexes
Spectral techniques
DNA interaction studies
Antimicrobial investigations
Ó 2013 Elsevier B.V. All rights reserved.
Introduction
states, ‘tune-ability’ of the thermodynamics and kinetics of ligand
substitution. On the basis of the structural and thermodynamic
Metals, in particular, transition metals offer potential advantages
over the more common organic-based drugs. For example, a wide
range of coordination numbers and geometries, accessible redox
analogy between platinum(II) and palladium(II) complexes, there
is also much interest in the study of palladium(II) derivatives as po-
tential anticancer drugs [1–6].
Heterocyclic moieties can be found in a large number of
compounds which display biological activity. The biological
activity of the compounds is mainly dependent on their molecular
⇑
Corresponding author. Tel.: +91 80 22933354.
E-mail address: shivachemist@gmail.com (K.S. Prasad).
1386-1425/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.saa.2013.01.013

K.S. Prasad et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 107 (2013) 108–116
109
structures [7]. Schiff bases are bimolecular condensation products
of primary amines with aldehydes-represent valuable intermedi-
ates in organic synthesis and, at the same time, compounds with
various applications [8]. Schiff bases resulted from aromatic alde-
hydes ortho-substituted with a hydroxyl group have initially arouse
the researches interest because of their ability to act as bidentate li-
gands for transition metal ions [9]. Schiff bases are important class
of compounds due to their flexibility, structural similarities with
natural biological substances and also due to presence of imine
(C@N), which imports in elucidating the mechanism of transforma-
tion and rasemination reaction in biological system [10]. These no-
vel compounds could also act as valuable ligands whose biological
activity has been shown to increase on complexation [11].
spectroscopy in Tris–HCl/NaCl buffer (5 mMTris–HCl, 5 mMNaCl,
pH 7.2). The purity of CT-DNA was checked by measuring the
absorbance at 260 and 280 nm (A260/A280) which was found to be
1.81 in buffer solution [14].
Fluorescence spectral studies
In order to clarify the relative binding modes of complex with
CT-DNA, fluorescence spectral studies were carried out at fixed
complex concentration (3
tion (5, 10, 15, 20 and 25
l
M) and increasing CT-DNA concentra-
lM) [15]. The binding of the complexes
with CT-DNA is evaluated by the fluorescence emission intensity
of ethidium bromide (EB) bound to DNA as a probe [16].
Very recently, we have reported the synthesis and biological
activities of Schiff bases derived from 3-amino-2-methyl-4(3H)-
quinazolinone [12]. In this work, we report the synthesis, DNA
interaction studies and antimicrobial activity of new Pd(II) com-
plexes with quinolin-4(3H)-one Schiff base ligands. To the best of
our knowledge, Pd(II) complexes bearing 4(3H)-quinazolinone de-
rived ligands have not been described to date.
Viscosity measurements
Viscosity titration experiments were carried in buffer solution
on an Ostwald’s viscometer at room temperature by varying the
complex concentration at constant CT-DNA concentration
(40
lM). Flow time was measured with a digital stop watch. Each
sample was measured at least three times and average flow time
was calculated. Data were presented as (
1/3
g/g0
)
vs binding ratio
([complex]/[DNA]) [17], where was the viscosity value for DNA
g
in presence of the complex and g0 was the viscosity value of CT-
Experimental
DNA alone.
Materials and methods
DNA cleavage
The starting materials: 3-amino-2-methyl-4(3H)-quinazolinone
and substituted aldehydes was obtained from Aldrich. Palladium(II)
salts and solvents were commercially available of high purity and
used as such. CT-DNA (calf thymus DNA) was obtained from GENEI
laboratories, Bangalore. An elemental analysis was performed using
a Perkin-Elmer 240 elemental analyzer. Infrared spectra were re-
corded with a JASCO FT-IR spectrophotometer from 4000 to
400 cmÀ1 using Nujol mulls technique. The UV–Visble spectra were
recorded on Hitachi-3900 spectrophotometer. A Shimadzu TG-50H
thermo analyzer was used to record simultaneous TGA and DTG
curves in dynamic nitrogen atmosphere with a heating rate of
10 °C minÀ1, in the temperature range 20–700 °C using platinum
crucibles. 1H NMR spectra were recorded using Varian-400 MHz
spectrometer using DMSO-d6 as a solvent. Chemical shifts are re-
ported in parts per million downfield from tetramethylsilane. ESI-
MS were determined on Varian-2000 mass spectrometer.
The cleavage of plasmid DNA was monitored using agarose gel
electrophoresis: supercoiled pUC19 (0.5 lg) in Tris–HCl buffer
(50 mM) with 50 mMNaCl (pH 7.2) was treated with metal com-
plexes (10À3 M). The samples were incubated for 1 h at 37 °C. A
loading buffer containing 25% bromophenol blue, 0.25% xylene
cyanol and 25% glycerol were added and electrophoresis was per-
formed at 70 V for 2 h in TBE buffer using 1.0% agarose gel contain-
ing 1.0 lg/mL ethidium bromide [18]. Bands were visualized using
UV light and photographed. The cleavage efficiency was measured
by determining the ability of the complex to convert the super-
coiled DNA (Form I) to nicked circular form (Form II) or linear form
(Form III).
Synthesis
Synthesis of ligands (L1–L4)
Antimicrobial activity
A volume of 25 mL methanolic solution of 3-amino-2-methyl-
4(3H)-quinazolione (1.75 g, 10 mmol) was slowly added to a
15 mL of corresponding aldehyde (10 mmol in methanol). The
reaction mixture was stirred for 30 min and then refluxed for 4 h.
The completion of reaction was monitored by TLC. The solvent
was removed by distillation. The solid product obtained was
recrystallized from ethanol to yield respective ligand (L1–L4). The
structures of ligands are given in Fig. 1.
The In vitro antimicrobial activity of the test compounds were
evaluated against three bacteria; Bacillus subtilis (MTCC 121)
(Gram-positive), Staphylococcus aureus (MTCC 96) (Gram-positive)
and Escherichia coli (MTCC 1652) (Gram-negative) by agar discolor
diffusion method [13]. The test compounds were dissolved in di-
methyl sulfoxide (DMSO) to a final concentration of 1 mg/mL.
The bacteria were sub-cultured in nutrient agar medium, respec-
tively. Gentamycine was used as standard antibacterial drug, under
similar conditions for comparison. The inoculated Petri dishes were
incubated for 24 h at 37 °C. During this period, the test solution dif-
fused and the growth of the inoculated microorganisms was affected.
Activity was determined by measuring the diameter of zone showing
complete inhibition (mm). DMSO was used as control to clarify the
ambiguity (no activity was observed). All the compounds were
tested in triplicates and the average of three trails were reported.
N
O
N
O
H
C
N
H
C
N
N
N
N
HO
L2
L1
N
N
H
C
N
S
N
H
C
N
DNA interaction studies
N
O
O
HO
OCH3
DNA binding
L4
L3
The DNA binding activity of complexes 2 and 3 with calf thymus
DNA (CT-DNA) was performed by using electronic absorption
Fig. 1. Structures of Schiff base ligands.

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K.S. Prasad et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 107 (2013) 108–116
Table 1
Elemental analysis of Pd(II) complexes.
Compound
Molecular formula
Yield (%)
Found (calcd) (%)
C
H
N
M
L1
L2
L3
L4
1
2
3
4
C16H13N3O2
C15H12N4O
C17H15N3O3
C16H15N3OS
71
63
61
79
61
67
63
69
68.43 (68.51)
68.18 (68.27)
66.01 (66.12)
64.62 (65.13)
42.10 (42.31)
40.90 (41.12)
41.97 (42.09)
40.67 (40.86)
4.58 (4.61)
4.28 (4.31)
4.93 (5.03)
5.08 (5.14)
2.85 (2.97)
2.72 (2.88)
3.08 (3.19)
3.17 (3.29)
14.9 (15.02)
21.22 (21.32)
13.58 (13.79)
14.13 (15.61)
9.21 (9.35)
12.72 (12.94)
8.64 (8.79)
8.89 (9.02)
–
–
–
–
C
C
C
C
16H13N3O2PdCl2
15H12N4OPdCl2
17H15N3O3PdCl2
16H15N3OSPdCl2
23.24 (23.42)
24.09 (24.29)
21.81 (21.97)
22.45 (22.64)
Table 2
The important infrared frequencies (in cmÀ1) of Pd(II) complexes.
1 have molecular peaks; moreover, the peaks also provide support
for the suggested composition and structure of the complex.
Compound
t
(C@O)
t
(C@N)
t
(MAN)
t
(MAO)
L1
L2
L3
L4
1
2
3
4
1603
1597
1586
1574
1647
1653
1656
1651
1603
1684
1650
1656
1573
1598
1540
1565
–
–
–
–
443
427
423
438
–
–
–
–
404
409
411
406
Infrared spectroscopy
The important IR bands of Schiff base ligands and their corre-
sponding Pd(II) complexes are listed in Table 2.
The IR bands in the region 1682–1655 and 1655–1571 cmÀ1 in
the Schiff bases are attributed to the m(C@O) and m(C@N), respec-
tively. In the complexes 1–4, these bands are shifted to lower fre-
quencies at around 1656–1647 and 1602–1595 cmÀ1, indicating
the coordination of imine nitrogen and lactam oxygen atom to
the metal ion [19]. In the IR spectra of complexes 1 and 3, a very
broad band at ca. 3414 and 3434 cmÀ1 were observed which is
due to the OH group present in the Schiff bases L1 and L3, respec-
tively (Fig. 2), reveals that the phenolic oxygen is not involved in
the coordination [20].
Synthesis of metal complexes
The Pd(II) complexes of Schiff base ligands were prepared in 1:1
ratio. To a hot methanolic solution of palladium chloride (0.170 g,
1 mmol) in 20 mL, an appropriate Schiff base ligand solution was
added (L1–L4, 1 mmol) to obtain 1:1 complexes. The resulting mix-
ture was stirred under reflux for 4 h, where upon the complexes
were precipitated. They were collected by filtration, washed with
hot water, then diethyl ether and dried in air. The analytical and
physical data were reported in Table 1.
Electronic spectra
The electronic absorption spectra of the Schiff base metal
complexes in DMF were recorded at room temperature. Both the
complexes exhibit an absorption band in the range 360–390 nm,
which are assigned to charge transfer transition from the pp-orbi-
tals of the donor atoms to the d-orbitals of the metal. In addition,
Result and discussion
complexes exhibit d–d transition in the 617–724 nm range.
The complexes [PdCl2(L)] (where L = Schiff base ligands [L1–L4])
were obtained by reaction between the respective ligand (L1–L4)
and the palladium salt in aqueous medium. The desired product
is immediately formed as an amorphous precipitate upon addition
of the ligand to the palladium salt.
The elemental analyses were in good agreement with the pro-
posed formulas for the complexes. The reactions involved in the for-
mation of palladium complexes are well-known substitution
reactions of square-planar complexes which are favored by the
trans-effect of the chloride ligands. The mass spectra of the complex
1H NMR spectra
The 1H NMR spectra of ligand L3 and its complex 3 were
recorded in DMSO-d6 support the proposed structure of the
compounds. The signal due to azomethine proton of L3 at
8.71 ppm shows a downfield shift ca. 8.96 ppm [21] in the spectra
of complex 3 suggesting the coordination of the azomethine nitro-
gen to the metal ion. This downfield shift is due to desheilding of
110
100
50
40
30
%T
%T
20
50
0
10
0
4000
3000
2000
1000 600
4000
3000
2000
1000
400
Wavenumber [cm-1]
Wavenumber [cm-1]
(a)
(b)
Fig. 2. IR spectra of (a) L1 and (b) complex 1.

K.S. Prasad et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 107 (2013) 108–116
111
Fig. 3. 1H NMR spectrum of L1–L4.
the = CH proton. In Fig. 3, the signal at 10.03 ppm is due to the phe-
Mass spectra
nolic OH group in L3, which was found at same position in the com-
plex 3, indicating the non-involvement of phenolic oxygen atom in
the coordination. In L3, the multiplet ca. 7.0–8.2 ppm is due to the
aromatic protons and signal around 3.86 ppm is due to the meth-
oxy group.
The representative mass spectrum of complex 3 is showed in
Fig. 4. The molecular ion peak at m/z 486 corresponds to the
molecular weight of the complex 3. Also, the spectrum exhibited
peaks for the fragments at m/z 451, 416, 310, 188, 176, 161, 147

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K.S. Prasad et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 107 (2013) 108–116
Fig. 3. (continued)
and 129 which are summarized in Scheme 1. Similar fragmentation
pathway follows in all the complexes.
sphere. Fig. 4 shows the TG and DTG curves of complex 3. From
Fig. 5, it is clear that the complex do not lose weight up to
310 °C, indicating the absence of coordinated or lattice water mol-
ecules and the same result was confirmed by spectral studies. Fur-
ther rise in the temperature causes decomposition of complex in
two steps. The first decomposition spans from 320 °C through
380 °C corresponds to the liberation of chloride ion as HCl [22]
Thermal studies
The thermal decomposition behavior of complex 3 along with
the% weight at different temperatures is recorded under N2 atmo-

K.S. Prasad et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 107 (2013) 108–116
113
Fig. 4. Mass spectrum of complex 3.
N
CH3
N
N
C
H
O
Pd
HO
OCH3
Cl
Cl
m/z 486
N
N
CH3
N
C
H
O
HO
Pd
OCH3
Cl
m/z 451
N
N
CH3
N
C
H
O
Pd
HO
OCH3
m/z 416
N
N
CH3
N
C
H
O
HO
OCH3
m/z 310
N
N
N
N
N
N
N
CH3
NH
CH3
N
O
O
O
m/ z 12 9
m/z 147
m/z 161
m/z 176
Scheme 1. Mass fragmentation pattern of complex 3.
(found ꢀ15%). The second decomposition step starts at 380 °C and
terminates at about 490 °C, corresponding to the decomposition of
Schiff base ligand (found 64%) leaving behind metal oxide as the
end product [23]. Stepwise thermal degradation data of all com-
plexes were presented in Table 3.
Antibacterial activity
The contribution to the field of bioinorganic chemistry is impor-
tant, consequently, the synthesized Pd(II) complexes have been
evaluated for their antibacterial actions. The results of the bacteri-

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K.S. Prasad et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 107 (2013) 108–116
Table 4
In vitro antibacterial activity of the Schiff base ligands and their Pd(II) complexes.
Compound
Concentration (
l
g mLÀ1
)
Antibacterial activity (zone of
inhibition in%)*
B. subtilis
E. coli
S. aureus
L1
L2
L3
L4
1
2
3
4
100
100
100
100
100
100
100
100
45
33
54
35
78
67
80
67
48
39
52
40
81
72
83
66
44
37
51
38
78
77
81
71
Gentamycine 100
100
100
100
*
Average of three replicates.
Fig. 5. Thermogravimetric curve of complex 3.
shown in Fig. 7. Viscosity experimental results clearly show that
Pd(II) complex can stack between adjacent DNA base pairs, causing
an extension in the helix, and increase the viscosity of DNA.
cidal study of the synthesized compounds are reported in Table 4.
Further, the antibacterial action of ligands may be significantly en-
hanced on chelation with metal ions. From the bactericidal activity,
it is apparent that the complexes were more toxic towards gram
positive strains than gram negative strains. The reason is the differ-
ence in the structure of the cell walls [24]. The walls of gram neg-
ative cells are more complex than those of gram positive cells.
Further to it, the ligands showed moderate, and the complexes
showed moderate to high activities and were compared with stan-
dard drug towards the entire organism.
Fluorescence spectra
The fluorescence spectra of complexes 2 and 3 interacting with
CT-DNA were studied according to previously developed proce-
dures [27]. The spectra are shown in Fig. 8. The fluorescence inten-
sity of ethidium bromide (EtBr) [28] itself is very faint, but it was
shown to emit intense fluorescence light in the presence of DNA
due to its intercalation into DNA between base pairs. Upon addi-
tion of a second molecule, which binds to DNA more strongly than
EtBr, the DNA-induced EtBr emission would be quenched [29],
indicating the replacement of EtBr by the second molecule interca-
lated into DNA [30]. The binding isotherm of complexes 2 and 3 is
again indicative of non-intercalative binding of the complexes to
DNA.
DNA binding experiments
Fig. 6 shows the titration of the palladium(II) complex (2 and 3)
samples in the aqueous buffer solution (50 mM NaCl/5 mM Tris–
HCl, pH 7.1). The studies were performed by using a fixed complex
concentration (12
range of 0.5–2
lM) with increasing amounts of DNA over a
l
M. The intrinsic binding constants (Kb) of com-
plexes 2 and 3 were found to be 2.36 Â 103 and 2.21 Â 103 MÀ1
,
Nuclease activity
respectively. The results indicate the binding obtained here are
lower than that reported for classical intercalator [25]. Thus, com-
plexes are weak binders and they bind in an intercalative stacking
manner to the double helix [26].
The degree to which the four complexes could function as DNA
cleavage agents was examined using supercoiled pUC19 plasmid
DNA as the target. The efficiency of cleavage of these molecules
was probed using agarose gel electrophoresis [31]. Complexes 2
and 3 were found to promote the cleavage of pUC19 plasmid
DNA from supercoiled Form (I) to the nicked Form (II) or linear
Form (III) (Fig. 9). A little DNA-cleavage was observed for the con-
trol in which metal complex was absent. The complexes can induce
the obvious cleavage of the plasmid DNA at the concentration of
10À3 M in the presence and absence of an oxidant (H2O2).The dif-
ferent DNA-cleavage efficiency of the complexes may be due to
the different binding affinity of the complexes to DNA.
Viscosity measurements
In order to confirm the interactions between the prepared
complexes and DNA, viscosity measurements were carried out in
Tris-buffer solution. A stacking intercalation model results in the
lengthening the DNA helix as base pairs were separated to accom-
modate the complex, leading to the increase of DNA viscosity. The
effects of complexes 2 and 3 on the viscosity of CT-DNA at 25 °C are
Table 3
Stepwise thermal degradation data obtained from TGA curves and their composition.
Complex
Process
Temp. range (°C)
Products
% Weight loss
No. of moles
% Residue
Calcd
Nature
Calcd
Expt
Expt
C
C
C
C
16H13N3O2PdCl2
15H12N4OPdCl2
17H15N3O3PdCl2
16H15N3OSPdCl2
I
II
I
II
I
II
I
300–360
470–510
290–350
460–520
310–390
450–500
280–370
470–520
2HCl
15.78
61.14
16.36
60.00
14.40
63.78
14.83
62.71
15.52
60.86
16.12
59.49
13.91
62.69
14.18
61.93
2
1
2
1
2
1
2
1
26.75
26.37
PdO
PdO
PdO
PdO
C16H15N3O2
2HCl
27.72
25.10
25.84
27.29
24.77
25.12
C15H12N4O2
2HCl
C17H15N3O3
2HCl
C16H15N3OS
II

K.S. Prasad et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 107 (2013) 108–116
115
Fig. 6. Absorption spectra of (a) complex 2 and (b) complex 3, in Tris–HCl buffer upon addition of DNA = 1 Â 10À4 M, 0–25
ll. Arrow shows the absorbance changing upon
increasing the concentration of DNA.
Conclusions
The synthesized palladium(II) complexes with 4(3H)-quinazoli-
none derived Schiff base ligands have been characterized using dif-
ferent analytical, physical and spectroscopic techniques. The above
studies confirmed that the bonding of Schiff base ligands to metal
ion was through azomethine nitrogen and lactonyl oxygen atom.
The electronic spectral data suggested the square-planar geometry
for the complexes. The DNA binding propensity of the palladium(II)
complexes was determined by an electronic absorption spectros-
copy, fluorescence spectroscopy and viscometric studies. The data
obtained by binding studies revealed that the complexes bind in
stacking manner to the double helical DNA and thus, acts as weak
binding agents. The oxidative damage study of supercoiled pUC19
DNA with the complexes in the presence and absence of H2O2 re-
vealed that complexes acts as good cleaving agents both in the
presence and absence of an oxidant. The antimicrobial results of
the Schiff bases and their Pd(II) complexes show promising activity
against the selected microorganisms. In particular, ligands L1 and
L3 and their corresponding complexes 1 and 3 showed very potent
activity compared to other compounds, respectively.
Fig. 7. Effect of increasing amount of complexes 2 and 3 on the relative viscosity of
CT-DNA.
Fig. 8. Emission spectra of the complexes (a) 2 and (b) 3 inTris–HCl buffer upon addition of calf-thymus DNA. [complex] = 1 Â 10À5 M, [DNA] = (0–5) Â 10À5 M. Arrow shows
the intensity changing upon increasing DNA concentrations.

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[4] F.V. Rocha, C.V. Barra, A.V.G. Netto, A.E. Mauro, I.Z. Carlos, R.C.G. Frema, S.R.
Ananias, M.B. Quilles, A. Stevanato, M.C. da Rocha, Eur. J. Med. Chem. 45 (2010)
1698–1702.
[5] J. Ruiz, J. Lorenzo, C. Vicente, G. López, J.M. López-de-Luzuriaga, M. Monge, F.X.
Avilés, D. Bautista, V. Moreno, A. Laguna, Inorg. Chem. 47 (2008) 6990–7001.
[6] E.J. Gao, M.C. Zhu, Y. Huang, L. Liu, H.Y. Liu, F.C. Liu, S. Ma, C.Y. Shi, Eur. J. Med.
Chem. 45 (2010) 1034–1041.
[7] E.A. Elzahany, K.H. Hegab, S.K.H. Khalil, N.S. Youssef, Aust. J. Basic Appl. Sci. 2
(2) (2008) 210–220.
[8] H.I. Ugras, I. Basaran, T. Kilic, U. Cakir, J. Heterocycl. Chem. 43 (2006) 1679–
1684.
[9] S.J. Wadher, M.P. Puranik, N.A. Karande, P.G. Yeole, Int. J. Pharm Technol. Res. 1
(1) (2009) 22–33.
[10] P. Rajavel, M.S. Senthil, C. Anitha, E-J. Chem. 5 (3) (2008) 620–626.
[11] G.G. Mohamed, M.M. Omar, A.M. Hindy, Turk. J. Chem. 30 (2006) 361–382.
[12] H.D. Revanasiddappa, K. Shiva Prasad, L. Shiva Kumar, B. Jayalakshmi, Int. J.
Chem. Tech. Res. 2 (2010) 1244–1249.
[13] C.H. Collins, P.M. Lyne, J.M. Grange, Microbiological Methods, sixth ed.,
Butterworths, London, UK, 1989.
Fig. 9. Cleavage of supercoiled pUC19 DNA (0.5 lg) by the Pd(II) complexes 2 and 3
in a buffer containing 50 mM Tris–HCl at 37 °C (30 min): lane M: marker. lane 1:
DNA control. lane 2: complex
2
(10À3 M) + DNA. lane 3: complex
3
2
(10À3
-
3
M) + DNA + H2O2. lane 4: complex
(10À3 M) + DNA. lane 5: complex
[14] K.R. Rupesh, S. Deepalatha, M. Krishaveni, R. Venkatesan, S. Jayachandran, Eur.
J. Med. Chem. 41 (2006) 1494–1503.
(10À3 M) + DNA + H2O2.
[15] Farukh Arjmand, A. Jamsheera, Spectrochim. Acta A. 78 (2011) 45–51.
[16] G.S. Son, J.A. Yeo, M.S. Kim, A. Holmen, B. Akerman, B. Norden, J. Am. Chem.
Soc. 120 (1998) 6451–6457.
[17] G. Cohen, H. Einsenberg, Biopolymers 8 (1969) 45–55.
[18] N.S. Biradar, V.H. Kulkarni, J. Inorg. Nucl. Chem. 33 (1971) 3781–3786.
[19] K. Shiva Prasad, L. Shiva Kumar, S. Chandan, B. Jayalakshmi, H.D.
Revanasiddappa, Spectrochim. Acta A 81 (2011) 276–282.
[20] A. Szorsik, L. Nagy, L. Pellerito, T. Yamaguchi, K.J. Yoshida, Raditional. Nucl.
Chem. 256 (2003) 3–10.
Acknowledgements
The authors are grateful to the University of Mysore for labora-
tory facilities. One of the author, K. Shiva Prasad is thankful to the
UGC-New Dehli for the award of Meritorious Fellowship. The
authors are also thankful to the Head, Department of Biotechnol-
ogy University of Mysore for providing the facilities to perform
DNA interaction studies.
[21] B.S. Jhaumeer-Laulloo, M.G. Bhowon, Intl. J. Chem. 42 (2003) 2536–2540.
[22] Sadaf Khan, A.A. Shahab Nami, K.S. Siddiqi, Eram Husain, Imrana Naseem,
Spetrochim. Acta A 72 (2009) 421–428.
[23] I.T. Ahmed, Spectrochim. Acta A 65 (2006) 5–10.
[24] Shaukat Shujha, Afzal Shah, Zia-ur-Rehman, Niaz Muhammad, Saqib Ali,
Rumana Qureshi, Nasir Khalid, Auke Meetsma, Eur. J. Med. Chem. 45 (2010)
2902–2911.
[25] M. Cory, D.D. McKee, J. Kagan, D.W. Henryand, J.A. Miller, J. Am. Chem. Soc. 107
(1985) 2528–2536.
Appendix A. Supplementary material
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.saa.2013.01.013.
[26] R. Senthil Kumar, V.S. Periasamy, C.P. Preethy, A. Riyasdeenand, M.A. Akbarsha,
Polyhedron 27 (2008) 1111–1118.
[27] E.J. Gao, D. Zhang, Q.-T. Liu, Acta Chim. Sinica 61 (2003) 1834–1841.
[28] Z.D. Bugarcic, G. Liehr, R. Eldik, Dalton Trans. 6 (2002) 951–959.
[29] H. Mansuri-Torshizi, R. Mital, T.S. Srivastava, J. Inorg. Biochem. 44 (1991) 239–
248.
[30] T. Hirohama, Y. Kuranuki, E. Ebina, H. Arii, M. Chikira, P. Tamil Selvi, M.
Palaniandavar, J. Inorg. Biochem. 99 (2005) 1205–1219.
[31] S. Ghosh, A.C. Barve, A.A. Kumbhar, A.S. Kumbhar, V.G. Puranik, P.A. Datar, U.B.
Sonawane, R.R. Joshi, J. Inorg. Biochem. 100 (2006) 331–339.
References
[1] L. Giovagnini, L. Ronconi, D. Aldinucci, D. Lorenzon, S. Sitran, D. Fregona, J. Med.
Chem. 48 (2005) 1588–1595.
[2] A.G. Quiroga, C. Navarro Ranninger, Coord. Chem. Rev. 248 (2004) 119–133.
[3] S. Ray, R. Mohan, J.K. Singh, M.K. Samantaray, M.M. Shaikh, D. Panda, P. Ghosh,
J. Am. Chem. Soc. 129 (2007) 15042–15053.