Conformational change of ternary copper(II) complexes of cationic Schiff-bases and N-heteroaromatic amines induced by intercalative binding to DNA

doi:10.1016/j.inoche.2011.05.047

Inorganic Chemistry Communications

Volume 14, Issue 9, September 2011, Pages 1461-1464

https://doi.org/10.1016/j.inoche.2011.05.047 Get rights and content

Abstract

DNA-fiber EPR spectra revealed that intercalative binding of the ternary copper(II) complexes of cationic Schiff-bases and N-heteroaromatic amines induced the rearrangement of coordination spheres of the complexes from tetragonal pyramidal to square planar geometries. The binding of the complexes was also characterized by UV–vis, CD and fluorescence spectroscopy together with DFT calculation of the conformational change. The synergetic effect of the intercalation, the electrostatic interaction and the rearrangement of the coordination spheres enhanced the oxidative and the photodynamic DNA cleavage activities.

Graphical abstract

Research highlights

► Ternary Cu(II) complexes of cationic Schiff-bases and N-heteroaromatic amines. ► Intercalation to DNA induced conformational change of the coordination spheres. ► The synergetic effect of intercalation, electrostatic interaction and the conformational change. ► Enhancement of the oxidative and photodynamic DNA cleavages.

Section snippets

Acknowledgements

This research was partly supported by a Grant-in-Aid for Scientific Research (No. 21550070) from MEXT (M.C.), Chuo University Grant for Special Research and the fund from the Institute of Science & Engineering, Chuo University.

References (17)

F. Li et al.
Talanta
(2008)
A.K. Patra et al.
J. Inorg. Biochem.
(2007)
A.K. Patra et al.
Inorg. Chem.
(2009)
S. Roy et al.
Polyhedron
(2010)
M. Chikira
J. Inorg. Biochem.
(2008)
A.H. Maki et al.
J. Chem. Phys.
(1958)
A.H. Maki et al.
J. Chem. Phys.
(1958)
A. Sigel, H. Siegel (Eds.) Metal Ions in Bilogical Systems, Dekker, 1996, 32, 33, and 2004,...
J.K. Barton
S. Ramakrishnan et al.
Inorg. Chem.
(2009)

There are more references available in the full text version of this article.

Cited by (27)

Biological activity of mixed chelate copper(II) complexes, with substituted diimine and tridentate Schiff bases (NNO) and their hydrogenated derivatives as secondary ligands: Casiopeína's fourth generation
2023, Journal of Inorganic Biochemistry
We synthesize and characterize nine copper(II) compounds. Four with general formula [Cu(NNO)(NO₃)] and five mixed chelates [Cu(NNO)(N-N)]⁺, where NNO corresponds to asymmetric salen ligands (E)-2-((2-(methylamino)ethylimino)methyl)phenolate (L1) and (E)-3-((2-(methylamino)ethylimino)methyl)naphthalenolate (LN1); and their hydrogenated derivatives 2-((2-(methylamino)ethylamino)methyl)phenolate (LH1) and 3-((2-(methylamino)ethylamino)methyl)naphthalenolate (LNH1); and N-N correspond to 4,4′-dimethyl-2,2′-bipiridyne(dmbpy) or 1,10-phenanthroline (phen). Using EPR, the geometries of the compounds in solution in DMSO were assigned, [Cu(LN1)(NO₃)] and [Cu(LNH1)(NO₃)] a square-planar, [Cu(L1)(NO₃)], [Cu(LH1)(NO₃)], [Cu(L1)(dmby)]⁺ and [Cu(LH1)(dmby)]⁺ a square-based pyramid; and [Cu(LN1)(dmby)]⁺, [Cu(LNH1)(dmby)]⁺ and [Cu(L1)(phen)]⁺ and elongated octahedral. By X-ray it was observed that [Cu(L1)(dmby)]⁺ and. [Cu(LN1)(dmby)]⁺ presented a square-based pyramidal, and [Cu(LN1)(NO₃)]⁺ a square-planar geometry. The electrochemical study showed that copper reduction process is a quasi-reversible system, where the complexes with hydrogenated ligands were less oxidizing. The cytotoxicity of the complexes was tested by MTT assay, all the compounds showed biological activity in HeLa cell line, the mixed compounds were the more active ones. Naphthalene moiety, imine hydrogenation and aromatic diimine coordination, increased biological activity. A structure-activity relationships were found: Log(IC₅₀) = − 1.01(E_pc) − 0.35(Conjugated Rings) + 0.87, for Schiff base complexes and Log(IC₅₀) = 0.078(E_pc) − 0.32(Conjugated Rings) + 1.94, for hydrogenated complexes; the less oxidizing species with a great number of conjugated rings presented the best biological activity. Complexes-DNA binding constants were obtained by uv-vis studies using CT-DNA, the results suggested that the complexes can interact through the grooves, except the phenanthroline mixed complex that intercalate with DNA. Gel electrophoresis study with pBR 322 showed that compounds can produce changes in the form of DNA and some complexes can cleave DNA in the presence of H₂O₂.
Enzyme-free triple cycles triggered in-situ generation of nanospheres on DNA planar tripod for sensitive photoelectrochemical biosensor
2022, Sensors and Actuators B: Chemical
In this work, the non-sensitizer participated photoactive 3D DNA nanospheres in-situ generated on rigid planar DNA tripod was proposed for constructing a novel photoelectrochemical (PEC) biosensor to realize the ultrasensitive detection of miRNA-141. First, the slight targets could be efficiently converted into numerous output DNAs through the enzyme-free triple cycles, which thus opened the hairpin at apex of planar DNA tripod on electrode to trigger the rolling cycle amplification (RCA) for in-situ producing 3D DNA nanospheres with loading of plentiful positively charged photoactive species perylene derivative (PDA⁺). Impressively, the unique rigid planar DNA tripod could not only adjust the distance among each hairpin on vertexes for simply enhancing the hybridization efficiency toward output DNA with effective improvement in the generation of 3D DNA nanospheres, but also endow the highly efficient decoration of PDA⁺ approximated to electrode that beneficial to fast electron transport, thereby simply acquiring a low background and extremely high PEC signal without the need of sensitizers for improving detection sensitivity. As a result, the proposed approach showed a detection range from 0.1 fM to 100 pM for miRNA-141, providing a new and efficient strategy to construct sensitive PEC biosensor for potential application in early disease diagnosis and monitoring.
Chiral halogenated Schiff base compounds: green synthesis, anticancer activity and DNA-binding study
2018, Journal of Molecular Structure
Citation Excerpt :
As a conclusion, we can say that intermolecular and intramolecular hydrogen bonds cause that the enantiomers have different melting point and CD spectrum. Monitoring changes in the absorption spectra of the ligands upon addition of various amounts of DNA is a powerful technique for determining their overall DNA-binding characteristics [33]. Hypochromic and red shift in the UV-Vis spectrum of a drug upon its DNA-binding is indicative of intercalation mode, involving an interaction between π* orbital of the drug with π orbital of DNA base pairs.
Eight enantiomerically pure halogenated Schiff base compounds were synthesized by reaction of halogenated salicylaldehydes with 3-Amino-1,2-propanediol (R or S) in water as green solvent at ambient temperature. All compounds were characterized by elemental analyses, NMR (¹H and ¹³C), circular dichroism (CD) and FT-IR spectroscopy. FS-DNA binding studies of these compounds carried out by fluorescence quenching and UV–vis spectroscopy. The obtained results revealed that the ligands bind to DNA as: (RClBr) > (RCl₂) > (RBr₂) > (RI₂) and (SClBr) > (SCl₂) > (SBr₂) > (SI₂), indicating the effect of halogen on binding constant. In addition, DNA-binding constant of the S and R-enantiomers are different from each other. The ligands can form halogen bonds with DNA that were confirmed by molecular docking. This method was also measured the bond distances and bond angles. The study of obtained data can have concluded that binding affinity of the ligands to DNA depends on strength of halogen bonds. The potential anticancer activity of ligands were also evaluated on MCF-7 and HeLa cancer cell lines by using MTT assay. The results showed that the anticancer activity and FS-DNA interaction is significantly dependent on the stereoisomers of Schiff base compounds as R-enantiomers displayed significantly higher activity than S-enantiomers. The molecular docking was also used to illustrate the specific DNA-binding of synthesized compounds and groove binding mode of DNA interaction was proposed for them. In addition, molecular docking results indicated that there are three types of bonds (H and X-bond and hX-bond) between synthesized compounds and base pairs of DNA.
Pyridine Functionalized N-Heterocyclic Silane Complexes of Iridium and Rhodium-An Unexpected Change in Coordination
2018, Organometallics
A new pyridine functionalized N-heterocyclic silane with ambident reactivity as a ligand has been synthesized and characterized by NMR spectroscopy (¹H, ¹³C{¹H}, ²⁹Si), mass spectrometry, elemental analysis, and X-ray crystallography. This ligand reacts with iridium and rhodium cod precursors (cod = 1,5-cyclooctadiene) to yield two new complexes that possess divergent, and unexpected, binding properties. In particular, no oxidative addition occurs at the intraligand Si-H unit. With the iridium(I) center, the ligand acts as a tertiary amino-pyridine chelator, whereas coordination of rhodium(I) to the ligand occurs with arene π-complexation on an opposite side. The latter interaction yields an unprecedented, electronically induced, coordination change at the silicon center over a long spatial distance. The new iridium and rhodium compounds are of high interest as they provide two potentially different reactions sites in one complex and as these sorts of complexes are known to activate small molecules like dihydrogen or silanes. Hence, the compounds are promising candidates for applications in tandem catalysis. Furthermore, the rhodium complex might be utilized for molecular switches, sensors, and comparable applications.
Structural and cytotoxic studies of cationic thiosemicarbazones
2017, Journal of Molecular Structure
Schiff bases from the thiosemicarbazones family with variable N4 substituents are known to show enhanced growth inhibitory properties. In view of these facts and as a part of our continuous interest in cationic Schiff bases, we have developed several Schiff base ligands from (3-formyl-4-hydroxyphenyl)methyltriphenylphosphonium (T) in present study. The compounds were characterized by various spectroscopic methods (infrared spectra, ¹H NMR, ¹³C NMR, HRESIMS and X-ray crystallography). Three of the N4 substituents, namely P(tsc)T, FP(tsc)T and EP(tsc)T exerted strong growth inhibitory properties by inhibiting the highly metastasis prostate cancer growth (PC-3). The thiosemicarbazone with ethylphenyl (EP) moiety displayed most potent activity against all cell lines tested. The MTT data obtained from analysis establishes that phenyl substituent enhances the growth inhibitory properties of the compound. The result affirms that EP(tsc)T would serve as a lead scaffold for rational anticancer agent development.
DNA binding and cytotoxicity activity of a chiral iron(III) triangle complex based on a natural rosin product
2015, Journal of Photochemistry and Photobiology B: Biology
Citation Excerpt :
DNA is the primary target molecule for most anticancer and antiviral therapies [1], and synthesis of transition metal complexes that interact with DNA have long been an intense and basic research subject of bioinorganic chemistry with the aim of finding novel metal complexes as diagnostic probes, anticancer or therapeutic agents [2–4].
The first chiral trinuclear iron(III) complex [Fe₃(μ₃-O)(L)₆(CH₃OH)₂(CH₃O)]⋅H₂O (2) of a natural rosin product dehydroabietic acid (HL, 1) was synthesized and fully characterized. The interactions of 1 and 2 with salmon sperm DNA were investigated by viscosity measurements, UV, fluorescence and circular dichroism (CD) spectroscopic techniques. Absorption spectral (K_b = 1.30 × 10⁵ M⁻¹ (1), 1.40 × 10⁵ M⁻¹(2)), emission spectral (K_SV = 1.19 × 10⁴ M⁻¹ (1), 1.79 × 10⁴ M⁻¹ (2)) and viscosity measurements reveal that 1 and 2 interacted with DNA through intercalation and 2 exhibited a slight higher DNA binding ability. The Stern–Volmer quenching constant (K_SV) and corresponding thermodynamic parameters (ΔG, ΔH and ΔS) of the binding processes were determined. The negative ΔH and ΔG values indicate that the binding reactions were exothermic and spontaneous. 1 and 2 were also screened for their cytotoxic ability and 1 demonstrated higher growth inhibition of the selected cancer cells at concentrations of 25 μM and 50 μM, this result was not identical with their DNA binding ability order. Thus, the involvement of Fe(III) centers had positive effect on DNA binding ability and negative effect on cytotoxicity.

View all citing articles on Scopus

View full text

Conformational change of ternary copper(II) complexes of cationic Schiff-bases and N-heteroaromatic amines induced by intercalative binding to DNA

Abstract

Graphical abstract

Research highlights

Section snippets

Acknowledgements

Talanta

J. Inorg. Biochem.

Inorg. Chem.

Polyhedron

J. Inorg. Biochem.

J. Chem. Phys.

J. Chem. Phys.

Inorg. Chem.