Interaction of copper(II) complexes of bi and tridentate ligands with DNA and their antiproliferative effects on osteoscarcoma cancer cell

1. Ph. D. Viva Voce Examination University of Madras
Interaction of Copper(II) Complexes of Bi- and
Tridentate Ligands with DNA and their Anti-proliferative
Effects on Osteosarcoma Cancer Cell
S Rajalakshmi
Chemical Laboratory

2. Structure of Thesis
Chapter 1 Introduction
Chapter 2 Analytical techniques and experimental details
Chapter 3 Interaction of mixed ligand copper(II) complexes with DNA
and its anti-proliferative effects
Chapter 4 DNA condensation ability- benzimidazolylterpyridine
copper(II) complexes & its anti-proliferative effects
Chapter 5 Investigation of interaction of copper(II) complexes of
thiophenemethanamine derivatives with DNA & their anti-
proliferative effects
Chapter 6 Summary and conclusions
2

3. Chapter 1
INTRODUCTION
3

4. Need of Metal Ions in Biological System?
• Nature itself has incorporated many metal ions in biological system
• Metal ions must be obtained for growth & development
• Metal ions play tremendous role in biological system predominantly
in the cationic form
4

5. Need of Metal Ions in Biological System?
• Metal ions can have structural role, functional role & both
Metal Function
Na+, K+ Charge carrier, osmotic balance
Mg2+, Zn2+ Structural hydrolase, isomerase
Ca2+ Structural, charge carrier
V2+, Mo3+ Nitrogen fixation, oxidase
Mn2+ Photosynthesis, structural, oxidase
Fe2+, Cu2+ Dioxygen transport & storage, electron transfer, oxidase
Ni2+ Hydrogenase, Hydrolase
Knowing the indispensable role of metal ion in biological system
the use of metal complexes as therapeutic agent is the natural
step in medicinal chemistry
5

6. Pioneers of Metal Based Drugs
Salvarsan - Drug
• Treatment of syphilis
• Prof. Ehlrich Noble prize
- Immunochemistry
Aurothioglucose Sodium aurothiopropanol
sulfonate
Gold complexes – Chrysotherapy- Rheumatoid Arthritis
6

7. Anticancer Agents : Platinum Complexes
Lobaplatin
Cisplatin Carboplatin Nedaplatin
Oxaliplatin
7

8. Anticancer Agents: Non-Platinum Complex
KP1019 Tamoxifene
Casiopeinas
NAMI-A
Still there is a need for alternative
anti-cancer agents based on
transition metal complexes
8

9. • Copper is one of the third most abundant transition metal in living
systems
• Plants/Animals : Electron transfer/O2-carrying
• Cu-proteins and enzymes
Cytochrome oxidase O2→H2O
Tyrosinase, phenol oxidase ox. of phenols
Ceruloplasmin Fe(II) → Fe(III)
Blue proteins Electron transfer
Superoxide dismutase Elimination of O2
-
Hemocyanin O2 transport
• Biologically accessible redox potential
Cu(s)→ Cu2++2e− (-0.34 V)
Copper based complexes as an alternative
9

10. To design and synthesis planar aromatic to non-planar aliphatic
ligands and coordination with copper(II) salts for therapeutic
applications
Analyzing the DNA binding ability of the synthesized copper
complexes
Evaluating the synthetic nuclease activity of the synthesized
copper complexes
Deriving the relationship between mode of binding of copper
complexes to DNA against cytotoxic effects on cancerous and
normal cell lines
Objective
10

11. Chapter 2
Analytical Techniques and
Experimental Details
11

12. Analytical Techniques - Characterization
Ligands Metal complex
FT-IR spectroscopy Elemental analysis
Electronic absorption
spectroscopy
FT-IR spectroscopy
Fluorescence spectroscopy ESI-Mass spectrometry
Nuclear magnetic resonance
spectroscopy
Electron paramagnetic
resonance spectroscopy
ESI-Mass spectrometry Electronic absorption
spectroscopy
Fluorescence spectroscopy
Single crystal X-ray diffraction
12

13. Analytical Techniques: Metal Complex-
Biomolecules Interaction
Metal complex-DNA
Binding studies
Effect of MC on DNA
Condensation and
Cleavage studies
Anti-proliferative
studies
Electronic absorption
spectroscopy
Electrophoretic mobility
assay
Microscopy
Fluorescence
spectroscopy
Dynamic light scattering
spectroscopy
Electronic absorption
spectroscopy
Rheological
measurements
Fluorescence
microscopy
Circular dichroism
spectroscopy
MTT assay &
Apoptotic assay
Molecular docking
studies
13

14. Schematic Representation: Synthesis of
Ligands
ptpy - pyridine-2-carbaldehyde (L2); meotpy – 4-methoxybenzaldehyde
(L3); benzimidazole-2-aldehyde – bitpy (L4) (i)
Synthesis of terpyridyl derivatives
imidazole – ithma (L5)
pyridyl– pythma (L6)
benzimdiazolyl – bzthma (L7) (ii)
(L1)
14
Synthesis of thiophenemethanamine derivatives
(i) G. W. V. Cave, C. L. Raston, J. Chem. Soc. Perkin Trans. I, 2001, 3258. (ii) P. Kumar et al., Dalton Trans. 2012, 41, 7573-7581

15. 4’X-terpy + Cu(NO3)2.3H2O + dmp → [Cu(4’X-terpy)(dmp)]2+
2bitpy + Cu(ClO4)2.6H2O → [Cu(bitpy)]2+
bitpy + Cu(NO3)2.3H2O + bpy → [Cu(terpy)(bpy)]2+
bitpy + Cu(NO3)2.3H2O → [Cu(bitpy)(NO3)]+
2imthma + Cu(ClO4)2.6H2O → [Cu(imthma)]2+
2bzthma + Cu(NO3)2.3H2O → [Cu(bzthma)(NO3)]2+
2pythma + Cu(NO3)2.3H2O → [Cu(pythma)(NO3)]2+
Synthesis of Copper(II) Complexes
15
rt
Δ
rt
rt
(1-3)
(4)
(5)
(6)
(7)
(8)
(9)
Δ
Δ
Δ

16. Chapter 3
Interaction of Mixed Ligand
Copper(II) Complexes with DNA and
its Anti-proliferative Effects
16

17. Synthesis of Mixed Ligand Copper(II)
Complexes
[Cu(itpy)(dmp)]2+
(1)
[Cu(ptpy)(dmp)]2+
(2)
[Cu(meotpy)(dmp)]2+
(3)
17

18. Complex UV-Visible Spectroscopy
λmax (nm)
ESI-MS
(m/z)
FT-IR
cm-1
1 218, 275, 343, 591-645 285.34 3396, 2926,
1618, 1384,
1029, 794
2 212, 276, 350, 580-640 291.34 3395, 3024,
1595, 1384,
1337, 856
3 218, 277, 343, 595-680 305.20 3399, 2918,
1599, 1384,
1017, 837
Characterization of Cu(II) Complexes
18

19. ORTEP
representation:
Distorted square
pyramidal (4+1)
X-ray Diffraction of [Cu(itpy)(dmp)](NO3)2
Complex Bond distance/Å
Cu(1) - N(12) 1.931(2)
Cu(1) - N(42) 1.980(2)
Cu(1) - N(1) 2.037(2)
Cu(1) - N(18) 2.053(2)
Cu(1) - N(31) 2.219(2)
19
2.219 (2) Å from dmp ligand
Jahn Teller Distortion
τ = 0.33
Basal plane from itpy and
one from dmp

20. ORTEP representation:
Between trigonal
bipyramidal and square
pyramidal
Complex Bond distance/Å
Cu(1)-N(12) 1.926(2)
Cu(1)-N(18) 2.013(2)
Cu(1)-N(1) 2.032(2)
Cu(1)-N(42) 2.067(2)
Cu(1)-N(31) 2.114(2)
X-ray Diffraction of [Cu(ptpy)(dmp)](NO3)2
20
τ = 0.63
Cu-N(eq) ≈ Cu-N(ax)
Sq pyramidal trigonal bipyramidal
Basal plane from both N of dmp ligand
and from terpy ligand

21. X-ray Diffraction of [Cu(meotpy)(dmp)](NO3)2
21
ORTEP representation:
Distorted trigonal
bipyramidal (3+2)
Complex Bond distance/Å
Cu(1)-N(12) 1.935(2)
Cu(1)-N(42) 1.994(2)
Cu(1)-N(1) 2.035(2)
Cu(1)-N(18) 2.048(2)
Cu(1)-N(31) 2.222(2)
τ = 0.89
2Cu(ax) bond distances are 2.03 &
2.04Å by terpy ligand
Cu-N(31) Jahn Teller distortion
Basal plane from dmp ligand and
one from terpy ligand

22. Liquid Nitrogen Temperature
Cu(II) complexes in DMSO
Complex 1 gǁ : 2.22; g┴ : 2.05
Complex 2 gǁ : 2.22; g┴ : 2.04
Complex 3 gǁ : 2.22; g┴ : 2.06
gǁ > g┴
EPR of Complexes 1-3
22

23. DNA Binding and Cleavage Studies
23

24. Electronic Absorption Studies
Complex 1
Kb = 3.35 (±0.32) × 105 M-1
Both complexes are groove binders – Increase in absorbance
with increase in the concentration of complexes
24
Complex 2
Kb = 2.37 (±0.21) × 105 M-1

25. Electronic Absorption Studies
Intercalative mode of binding – Decrease in absorbance with
increase in the concentration of complex
25
Complex 3
Kb = 7.10 (±0.25) × 104 M-1

26. Viscosity Measurements
Effect of complexes 1, 2 and 3 (0–200 µM) on the viscosity
of CT-DNA (200 µM)
Complex 1 & 2– Random changes - Groove binders
Complex 3 - Linear increase - Intercalator
26

27. Gel Electrophoretic Mobility Assay
1 2 3 4 5 6
Complex 1
Form II
Form III
Form I
Complexes 1 & 2 in the presence of minor groove binder
Lane 1 : DNA alone
Lane 2 : DNA + 10 µM Complex 1
Lane 3 : DNA + 20 µM Complex 1
Lane 4 : DNA + 30 µM Complex 1
Lane 5 : DNA + 40 µM Complex 1
Lane 6 : DNA + 50 µM Complex 1
Lane 1 : DNA alone
Lane 2 : DNA + H2O2
Lane 3 : DNA + 10 µM Complex 2 + H2O2
Lane 4 : DNA + 20 µM Complex 2 + H2O2
Lane 5 : DNA + 30 µM Complex 2 + H2O2
Lane 1 : DNA + 2 µl DMSO
Lane 2 : DNA + 2 µl Distamycin (Dist)
Lane 3 : DNA + 20 µM Complex 1 + 2 µl Dist
Lane 4 : DNA + H2O2 + 20 µM Complex 2 + 2 µl Dist
Lane 5 : DNA + H2O2 + 20 µM Complex 2 + 2 µl DMSO
27
Complex 2
1 2 3 4 5
Form II
Form III
Form I
1 2 3 4 5
Form II
Form III
Form I

28. Gel Electrophoretic Mobility Assay-
Complex 3
Form II
Form I
1 2 3 4 5 6
Lane 1 : DNA alone
Lane 2 : DNA + 10 µM Complex 3
Lane 3 : DNA + 20 µM Complex 3
Lane 4 : DNA + 30 µM Complex 3
Lane 5 : DNA + 40 µM Complex 3
Lane 6 : DNA + 50 µM Complex 3
Complex 1 & 3 – Hydrolytic cleavage
Complex 2 – Oxidative cleavage
Complex 1 – Minor groove binder
Complex 2 – Major groove binder
28

29. Anti-proliferative Studies
Complex IC50 Values (µM)
NIH3T3 MG63
1 0.50 0.125
2 0.81 0.78
3 1.50 0.75
29
Complex
2

30. Phase Contrast and Fluorescence Image
30
• Complexes 1 & 3 at 0.125 and 0.75 µM
• Both morphological changes and Annexin V & PI staining shows
apoptotic cell death

31. Caspase 3 and 9 Activities
• NIH3T3 - no significant differences in cas -3 and -9 activities
• MG63 - Complexes 1 & 3 showed two fold increase in Cas-3
activity
31

32. All the complexes are mixed ligands with five coordination geometry
Imidazole and pyridyl possessing terpyridyl groups containing
complexes shows minor and major groove binding aptitude towards
DNA whereas methoxybenzyl terpyridyl complex possesses
intercalation
Imidazole and methoxybenzyl terpyridine showed hydrolytic cleavage
whereas pyridylterpyridine underwent oxidative cleavage
To rationalize among groove binders the minor groove has greater
antiproliferative effects on cancerous cells
Amongst groove binders and intercalators, imidazolylterpyridine minor
groove binder showed greater selectivity and low IC50 on cancerous
cells
Salient Features
32

33. DNA Condensation Ability of
benzimidazolylterpyridine
Copper(II) Complexes and its Anti-
proliferative Effects
Chapter 4
33

34. Synthesis of Varying Coordination of
Copper(II) Complexes
34
[Cu(bitpy)(phen)]2+
(5)
[Cu(bitpy)(NO3)2]2+
(6)
[Cu(bitpy)2]2+
(4)
2+
2+
2+

35. Complex UV-Visible Spectroscopy
λmax (nm)
FT-IR
cm-1
4 270, 287, 354, 580-680 3069, 1613, 1548, 1472,
1089, 792, 625
5 270, 350, 580-660 3367, 3188, 1665, 1614,
1384, 849, 720
6 288, 355, 680-730 3069, 1613, 1548, 1472,
1089, 792
Characterization of Complexes
35

36. ESI-MS of [Cu(bitpy)2]2+
36
Base peak as molecular ion peak
[Cu(bitpy)2]2+
Complex ion pair
[Cu(bitpy)2]+.ClO4

37. ESI-MS of [Cu(bitpy)(phen)](NO3)2
37
[Cu(bitpy)(phen)]2+
[[Cu(bitpy)] 2+NO3]+
[Cu(bitpy)(phen)]2+NO3

38. ESI-MS of [Cu(bitpy)(NO3)2]+
38
[Cu(bitpy)(NO3)]+
[Cu(bitpy)(CH3CN)]2+

39. EPR Spectrum of Complexes 4-6
39
Liquid Nitrogen Temperature
Cu(II) complexes in DMSO
Complex 4 gǁ : 2.22; g┴ : 2.05
Complex 5 gǁ : 2.22; g┴ : 2.04
Complex 6 gǁ : 2.22; g┴ : 2.06
gǁ > g┴

40. DNA Binding and Condensation
Studies
40

41. Complex 4 Kb = 1.84 (± 0.32) X 104 M-1
Complex 5 Kb = 1.83 (± 0.57) X 104 M-1
Complex 6 Kb = 1.87 (± 0.21) X 104 M-1
Electronic Absorption Studies
41
Intercalation - Almost similar
binding efficacy of all the three
complexes due to bitpy ligand

42. Viscosity Measurements
Linear increase confirming intercalative mode of binding of
three complexes to DNA
42

43. Circular Dichroic Spectral Analysis
Complex 4 shows greater changes in the helicity and 7 nm red-
shift
Complex 5 shows relatively less changes in the helicity whereas
base stacking has been blue-shifted to 7-9 nm
43

44. Circular Dichroic Spectral Analysis
CD bands Positive band Negative band
[Cu(bitpy)2](ClO4)2 (4) 4 nm (red-shift) 4 nm (red-shift)
[Cu(bitpy)(phen)](NO3)2 (5) 7 nm (blue-shift) 2 nm (red-shift)
[Cu(bitpy)(NO3)]NO3 (6) 3 nm (red-shift) 4 nm (red-shift)
Complex 6 shows greater
changes in the helicity and 3
nm red-shift
44

45. Electrophoretic Mobility Assay
Complex 4 Complex 5 Complex 6
Lane 1 : DNA alone
Lane 2 : DNA + 10 µM - 4
Lane 3 : DNA + 20 µM - 4
Lane 4 : DNA + 30 µM - 4
Lane 5 : DNA + 40 µM - 4
Lane 6 : DNA + 50 µM - 4
Lane 7 : DNA + 60 µM - 4
Lane 1 : DNA + 5 µM - 5
Lane 2 : DNA + 10 µM - 5
Lane 3 : DNA + 20 µM - 5
Lane 4 : DNA + 30 µM - 5
Lane 5 : DNA + 40 µM - 5
Lane 6 : DNA + 50 µM - 5
Lane 7 : DNA + 60 µM - 5
Lane 1 : DNA alone
Lane 2 : DNA + 10 µM - 6
Lane 3 : DNA + 20 µM - 6
Lane 4 : DNA + 30 µM - 6
Lane 5 : DNA + 40 µM - 6
Lane 6 : DNA + 50 µM - 6
Lane 7 : DNA + 60 µM - 6
Complex 4 brings about cleavage at low concentration
Complex 5 shows complete condensation since 5 – 60 µM
Complex 6 shows both condensation and hydrolytic cleavage
45

46. Anti-proliferative Studies
Complex IC50 Values (µM)
NIH3T3 MG63
4 60.0 1.0
5 5.0 1.2
6 1.0 1.0
46
Complex
6

47. Morphological Changes- Phase Contrast
Images
47
10µm
10µm
(a) Cell Shrinkage and chromatin condensation
(b) Membrane blebbing observed in MG63 cell line
(a) (a) (b)
• Complexes at IC50 concentrations

48. Annexin V & PI Staining: Caspase 3 and 9
Activities
N1 = Complex 4 at 1.0 µM
N2 = Complex 5 at 1.2 µM
48
NIH3T3 - no significant
differences in cas -3 and -9
activities
MG63 - Complex 4 showed six
fold increase in Cas-3 & -9
activity
10µm10µm

49. Six-, Five- and Four coordinated complexes with
benzimidazole head groups have been synthesized
4 ~ 5 ~ 6 almost equal binding affinity towards CT-DNA
DNA condensation of complexes follows the order: 4 > 5 > 6
The anti-proliferative effects of the complexes are 4 > 5 whose
IC50 values are relatively lower and showed greater selectivity
towards MG63 cells
Salient Features
The cell death occurs
via apoptosis and it is
by mitochondrial
mediated pathway
which have been
proved by caspase
activity
49

50. Investigation of Cu(II) Complexes of
Thiophenemethanamine Derivatives
with DNA and their Cytotoxicity Profile
Chapter 5
50

51. Structure of Thiophenemethanamine
Derivatives of Cu(II) Complexes
51
[Cu(imthma)2]2+
(7)
[Cu(bzthma)2]2+
(8)
[Cu(pythma)2]2+
(9)

52. Complex UV-Visible Spectroscopy
λmax (nm)
FT-IR
cm-1
7 208, 440-780 3396, 2926, 1618, 1384,
1029, 794
8 210, 270, 277, 520-790 3395, 3024, 1595, 1384,
1337, 856
9 208, 260, 550-800 3399, 2918, 1599, 1384,
1017, 837
Characterization of Cu(II) Complexes
52

53. ESI-MS and EPR Spectra of Complex 7
53
Mol. Ion peak
[Cu(imthma)2]2+
gǁ : 2.29
g┴ : 2.07
Aǁ : 149G
Distorted square
planar geometry

54. 54
[Cu(bzthma)2-H]+
ESI-MS and EPR Spectra of Complex 8
gǁ : 2.31
g┴ : 2.08
Aǁ : 149G
Distorted square
planar geometry

55. 55
gǁ : 2.30
g┴ : 2.08
Aǁ : 155G
Distorted square
planar geometry
ESI-MS and EPR Spectra of Complex 9
Mol. Ion peak
[Cu(pythma)2]2+

56. ORTEP Representation of Complex 7
56
Complex Bond distance/Å
Cu-N(1) 1.942(1)
Cu-N(3) 2.054(1)
Cu-N(1)# 1.942(1)
Cu-N(3)# 2.054(1)
• Uncoordinated sulfur
atom is evident from XRD
• EPR confirmed Square
planar geometry

57. DNA Binding and Cleavage Studies
57

58. Competitive Binding Studies
58
Complex 7 Kapp = 10.0 (± 0.23) × 105 M-1
Complex 8 Kapp = 6.30 (± 0.31) × 105 M-1
Complex 9 Kapp = 8.31 (± 0.19) × 105 M-1
Complexes 7-9 show groove
binding ability towards DNA

59. Fluorescence Spectra of Complexes
59
Complex Stern-Volmer quenching
constant (M-1)
Absence of
DNA
Presence of
DNA
7 4.61 x 103 4.32 x 103
8 2.33 x 103 2.08 x 103
9 3.90 x 103 4.11 x 103
[Fe(CN)6]4- shows groove binding

60. (a) DNA alone (b) DNA+Complex 7
(c) DNA+Complex 8 (d) DNA+Complex 9
Circular Dichroic Spectral and Viscosity
Measurements
Complexes 7 & 9 showed groove binding
For complex 8 intercalation mode of binding cannot be ruled out
60

61. Molecular Docking Studies
Duplex sequence d(CGCGAATTCGCG)2 PDB NO: 355D
Autodock Vina 1.0
Complex 7 Complex 8 Complex 9
61
Complexes 7 & 9 bind to the grooves of DNA
Complex 8 showed partial intercalation via., major groove

62. Agarose Gel Electrophoresis: Cleavage of
Complexes in the Presence of H2O2
Form II
Form III
Form I
Lane 1: DNA
Lane 2: DNA+ H2O2
Lane 3: DNA + 10μM - 7 + H2O2
Lane 4: DNA + 20μM - 7 + H2O2
Lane 5: DNA + 30μM - 7 + H2O2
Lane 1: DNA
Lane 2: DNA+ H2O2
Lane 3: DNA+ 10μM - 8 + H2O2
Lane 4: DNA+ 20μM - 8 + H2O2
Lane 5: DNA+ 30μM - 8 + H2O2
Lane 6: DNA+ 40μM - 8 + H2O2
Lane 1: DNA
Lane 2: DNA+ H2O2
Lane 3: DNA+ 10μM - 9 + H2O2
Lane 4: DNA+ 20μM - 9 + H2O2
Lane 5: DNA+ 30μM - 9 + H2O2
Lane 6: DNA+ 40μM - 9 + H2O2
Lane 7: DNA+ 50μM - 9 + H2O2
Complex 7 Complex 8 Complex 9
62
All the complexes showed oxidative cleavage in the
presence of hydrogen peroxide
1 2 3 4 5 1 2 3 4 5 6 1 2 3 4 5 6 7

63. Anti-Proliferative Studies
Complex IC50 Values (µM)
NIH3T3 MG63
7 5.0 5.0
8 40.0 4.0
9 40.0 7.5
63
Complex
7

64. Morphological Changes- Phase Contrast
Images
64
(a) (b)
Complexes at IC50 concentration
(a) Membrane blebbing
(b) Cell Shrinkage and chromatin condensation observed
in MG63 cell line
10µm

65. Morphological Changes- Annexin V & PI
65
MG63
Cells
NIH3T3
Cells
10µm
10µm
Red Orange stain indicating apoptotic cell death induced by
complexes 8 and 9

66. Caspase Activities
66
Complex 8 - benzimidazolyl derivative showed significant
increase in caspase activities compared to normal cells

67. Three copper(II) complex of thiophenemethylamine derivatives
have been synthesized and characterized
Complexes 7 & 9 possess groove binding whereas 8 possess
partial intercalation ability to CT-DNA in the binding order of
105
Gel electrophoresis shows complexes possess nuclease
activity in the presence of peroxide. The cleavage efficiency is
in the order: complex 7>8~9
Salient Features
Anti-proliferative effects on
MG-63 cells follows
benzimidazolyl > pyridyl >
imidazolyl
Apoptotic cell death and the
mitochondrial mechanistic
pathway has been proved
67

68. Summary and Conclusion
Chapter 6
68

69. Complexes 1-3 are five coordinate complexes with varying
substituent at 4’ position of terpyridine (imidazole, pyridyl
and methoxybenzyl moieties) and co-ligand is dmp
Complex 1 and 2 possess groove binding ability with DNA
whereas complex 3 binds intercalatively
Complex 1 is a minor groove binder, complex 2 is a major
groove binder which are evident from electrophoretic mobility
assay in the presence of distamycin
Complexes 1 & 3 cleaves DNA hydrolytically whereas
complex 2 cleaves oxidatively cleavage
Anti-proliferative studies reveals that complex 1 and 3
showed selectivity for cancerous cells whereas 2 is not
Summary and Conclusion
69

70. 70
Complexes 1 & 3 showed 4 & 2-fold selectivity on cancerous
cell (125 nM and 750 nM) than normal (500 nM and 1500 nM),
respectively
Summary and Conclusion
[Cu(itpy)(dmp)]2+ (1) [Cu(ptpy)(dmp)]2+(2) [Cu(meotpy)(dmp)]2+(3)
Complex 1 – minor groove binder – hydrolytic cleavage – 4-fold
cytotoxic effect on cancerous cells than normal cells

71. 71
Complexes 4-6, retaining the benzimidazolylterpyridine as a
common tridentate ligand in Cu(II) complexes with varying
coordination geometries
Complexes 4-6 bind to DNA intercalatively with equal binding
affinity (1.1 X 105 mol-1)
Complexes 4 and 5 showed DNA condensing ability at a
concentration of 10 and 5 µM, respectively whereas complex 6
cleaves DNA hydrolytically in addition to DNA condensation
Complexes 4 and 5 showed specificity on cancerous cells
whereas complex 6 is not
Amongst, complex 4 at a very low concentration of 1 µM
showed greater cytotoxic effect on MG63 cell line than normal
cell line (60 µM)
Summary and Conclusion

72. Complex 4 – intercalator – DNA condensing agent – 60-fold greater
anti-proliferative effect than normal cells
Summary and Conclusion
[Cu(bitpy)(phen)]2+
(5)
[Cu(bitpy)(NO3)2]2+
(6)
[Cu(bitpy)2]2+
(4)

73. Complexes 7-9 are thiophenemethanamine derivatives of
imidazolyl, benzimidazolyl and pyridyl units
Complex 7 & 9 are groove binders whereas complex 8 binds
with DNA via partial intercalation through major groove
confirmed using molecular docking studies
All these complexes (7-9) cleave DNA oxidatively
Complex 8-9 exhibit against cancerous cells (4 and 7.5 µM,
respectively) than normal cells (40 and 40 µM, respectively)
whereas complex 7 doesn’t
Complexes 8 & 9 show 10 & 5-fold selectivity on cancerous cell
than normal cell line
Summary and Conclusion

74. 74
Complex 8 – groove binder – oxidative cleavage – 10-fold higher
cytotoxic effects on cancerous cell line than normal cell line
Summary and Conclusion
[Cu(imthma)2]2+
(7)
[Cu(bzthma)2]2+
(8)
[Cu(pythma)2]2+
(9)

75. 75
[Cu(bitpy)2]2+ > [Cu(bzthma)2]2+ > [Cu(itpy)(dmp)]2+
(4) (8) (1)
Summary and Conclusion

76. List of Publications
Anomalous behavior of pentacoordinate copper complexes of
dimethylphenanthroline and derivatives of terpyridine ligands: Studies on DNA
binding, cleavage and apoptotic activity
S. Rajalakshmi, Thomas Weyhermüller, Allen J Freddy, Hannah R Vasanthi,
Balachandran Unni Nair *
European Journal of Medicinal Chemistry 46 (2011) 608-617
Copper (II) complexes possessing derivatives of terpyridine: An underpinning step
towards breast antiproliferative agent
S. Rajalakshmi, Thomas Weyhermüller, Balachandran Unni Nair*
Journal of Inorganic Biochemistry 117 (2012) 48-59
DNA cleavage activity by a mononuclear iron(II)Schiff base complex: Synthesis and
structural characterization
Pal, B. Biswas, M. Mitra, S. Rajalakshmi, C. S. Purohit, S. Hazra, G. S. Kumar,
Balachandran Unni Nair*, Rajarshi Ghosh*
Journal of Chemical Sciences 125 (2013) 1161-1168
76

77. List of Publications
DNA binding and cleavage activity of a structurally characterized oxobridged diiron(III)
complex
Biswas, M. Mitra, A. Pal, A. Basu, S. Rajalakshmi, P. Mitra, N. Aliaga-Alcalde, G. S.
Kumar, Balachandran Unni Nair *, Rajarshi Ghosh*
Indian Journal of Chemistry Vol. 52A, December (2013) 1576-1583
Investigation of nuclease, protelytic and anti-proliferative effects of copper(II)
complexes of thiophene methyl amine derivatives
S. Rajalakshmi, M S Kiran, V G Vaidyanathan, E R Azhagiya Singam, V
Subramaniam, and Balachandran Unni Nair*
European Journal of Medicinal Chemistry 46 (2013) 608-617
DNA condensing ability of copper(II) complexes and their anti-proliferative effect on
cancerous cell
S. Rajalakshmi, Manikantan Syamala Kiran, Balachandran Unni Nair*
European Journal of Medicinal Chemistry (2014) In Press
77

78. Acknowledgement
My Mentor

79. Acknowledgements
• Dr. Balachandran Unni Nair • Prof. A B Mandal
• Dr. Aruna Dhatthreyran • Dr. J Raghava Rao
• Dr. V Narayanan • Dr. V Subramanian
• Dr. M S Kiran • Dr K J Sreeram
• Dr. Thomas Weyhermuller • Dr Nishad Fathima
• Prof J Subramanian and CPL • Dr Easwaramoorthy
• Mr. D Muralidharan and CSIL • Dr. V G Vaidyanathan
• CSIR and DST • Mr. Azhagiya Singam
• SAIF, IIT Madras • Dr. K Sundaravel
• Seniors and Juniors • Dr. Yamini Asthana
Chemical Laboratory • Family and Friends CLRI!! 79

80. 80
Members of Chemical Laboratory

81. 81
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