Nickel-quinolones interaction. Part 2 - Interaction of nickel(II) with the antibacterial drug oxolinic acid

The mononuclear nickel(II) complexes with the first-generation quinolone antibacterial agent oxolinic acid in the presence or absence of nitrogen-donor heterocyclic ligands (2,2′-bipyridine, 1,10-phenanthroline or pyridine) have been synthesized and characterized. The experimental data suggest that oxolinic acid acts as deprotonated bidentate ligand coordinated to Ni(II) ion through the ketone and carboxylato oxygens. The crystal structure of (2,2′-bipyridine)bis(oxolinato) nickel(II), 2 has been determined by X-ray crystallography. The cyclic voltammograms of the complexes recorded in dmso solution and in 1/2 dmso/buffer (containing 150 mM NaCl and 15 mM trisodium citrate at pH 7.0) solution have shown that in the presence of calf-thymus DNA (CT DNA) they can bind to CT DNA by the intercalative binding mode. UV study of the interaction of the complexes with CT DNA has shown that the complexes bind to CT DNA and bis(aqua)bis(oxolinato) nickel(II) exhibits the highest binding constant to CT DNA. Competitive study with ethidium bromide (EB) has shown that the complexes can displace the DNA-bound EB indicating that they bind to DNA in strong competition with EB. The complexes exhibit good binding propensity to human or bovine serum albumin protein having relatively high binding constant values.     

Interaction of copper(II) with the non-steroidal anti-inflammatory drugs naproxen and diclofenac: synthesis, structure, DNA- and albumin-binding

Copper(II) complexes with the non-steroidal anti-inflammatory drugs (NSAIDs) naproxen and diclofenac have been synthesized and characterized in the presence of nitrogen donor heterocyclic ligands (2,2′-bipyridine, 1,10-phenanthroline or pyridine). Naproxen and diclofenac act as deprotonated ligands coordinated to Cu(II) ion through carboxylato oxygens. The crystal structures of (2,2′-bipyridine)bis(naproxenato)copper(II), , (1,10-phenanthroline)bis(naproxenato)copper(II), and bis(pyridine)bis(diclofenac)copper(II), have been determined by X-ray crystallography. The UV study of the interaction of the complexes with calf-thymus DNA (CT DNA) has shown that the complexes can bind to CT DNA with (2,2′-bipyridine)bis(naproxenato)copper(II) exhibiting the highest binding constant to CT DNA. Competitive study with ethidium bromide (EB) indicates that the complexes can displace the DNA-bound EB suggesting strong competition with EB. The cyclic voltammograms of the complexes recorded in the presence of CT DNA have shown that the complexes can bind to CT DNA by the intercalative binding mode which has also been verified by DNA solution viscosity measurements. The NSAID ligands and their complexes exhibit good binding propensity to human or bovine serum albumin protein having relatively high binding constant values. The biological properties of the previously reported complexes [Cu₂(naproxenato)₄(H₂O)₂], [Cu₂(diclofenac)₄(H₂O)₂] and [Cu(naproxenato)₂(pyridine)₂(H₂O)] have been also evaluated. The dinuclear complexes exhibit similar affinity for CT DNA as the 2,2′-bipyridine or 1,10-phenanthroline containing complexes. The pyridine containing complexes exhibit the lowest affinity for CT DNA and the lowest ability to displace EB from its EB-DNA complex.     

Nickel-quinolones interaction: Part 3 — Nickel(II) complexes of the antibacterial drug flumequine

Nickel(II) complexes with the first-generation quinolone antibacterial agent flumequine in the presence or absence of nitrogen donor heterocyclic ligands (4-benzylpyridine, pyridine, 2,2′-bipyridine or 1,10-phenanthroline) have been structurally characterized by physicochemical and spectroscopic techniques. The experimental data suggest that flumequine acts as deprotonated bidentate ligand coordinated to Ni(II) through the carboxylato and ketone oxygen atoms. The crystal structures of bis(4-benzylpyridine)bis(flumequinato)nickel(II) 2, (2,2′-bipyridine)bis(flumequinato)nickel(II) 4 and (1,10-phenanthroline)bis(flumequinato)nickel(II) 5 have been determined by X-ray crystallography and are the first crystal structures of flumequinato complexes reported. UV study of the interaction of the complexes with calf-thymus DNA (CT DNA) has shown that the complexes bind to CT DNA and bis(aqua)bis(flumequinato)nickel(II) exhibits the highest binding constant to CT DNA. Competitive study with ethidium bromide (EB) has shown that the complexes can displace the DNA-bound EB indicating that they bind to DNA in strong competition with EB. The cyclic voltammograms of the complexes recorded in DMSO solution and in 1/2 DMSO/buffer (containing 150 mM NaCl and 15 mM trisodium citrate at pH 7.0) solution have shown that in the presence of CT DNA they bind to CT DNA by the intercalative binding mode. The complexes exhibit good binding propensity to human or bovine serum albumin protein having relatively high binding constant values.     

Nickel-quinolones interaction. Part 4. Structure and biological evaluation of nickel(II)-enrofloxacin complexes compared to zinc(II) analogues

The nickel(II) complexes with the second-generation quinolone antibacterial agent enrofloxacin in the presence or absence of the nitrogen-donor heterocyclic ligands 1,10-phenanthroline, 2,2′-bipyridine or pyridine have been synthesized and characterized. Enrofloxacin acts as bidentate ligand coordinated to Ni(II) ion through the ketone oxygen and a carboxylato oxygen. The crystal structure of (1,10-phenanthroline)bis(enrofloxacinato)nickel(II) has been determined by X-ray crystallography. UV study of the interaction of the complexes with calf-thymus DNA (CT DNA) has shown that they bind to CT DNA and bis(pyridine)bis(enrofloxacinato)nickel(II) exhibits the highest binding constant to CT DNA. The cyclic voltammograms of the complexes have shown that in the presence of CT DNA the complexes can bind to CT DNA by the intercalative binding mode which has also been verified by DNA solution viscosity measurements. Competitive study with ethidium bromide (EB) has shown that the complexes can displace the DNA-bound EB indicating that they bind to DNA in strong competition with EB. The complexes exhibit good binding propensity to human or bovine serum albumin protein having relatively high binding constant values. The biological properties of the complexes have been evaluated in comparison to the corresponding Zn(II) enrofloxacinato complexes as well as Ni(II) complexes with the first-generation quinolone oxolinic acid.     

Non-steroidal anti-inflammatory drug diflunisal interacting with Cu(II). Structure and biological features

Copper(II) complexes with the non-steroidal anti-inflammatory drug diflunisal in the presence of N,N-dimethylformamide or nitrogen donor heterocyclic ligands (pyridine, 1,10-phenanthroline, 2,2′-bipyridine or 2,2′-bipyridylamine) have been synthesized and characterized. The deprotonated diflunisal ligands are coordinated to Cu(II) ion through carboxylato oxygen atoms. The crystal structures of [tetrakis(diflunisal)bis(N,N-dimethylformamide)dicopper(II)] 1 and [bis(diflunisal)bis(pyridine)copper(II)], 2 have been determined by X-ray crystallography and are the first reported crystal structures of diflunisal complexes. UV study of the interaction of the complexes with calf-thymus DNA (CT DNA) suggests binding of the complexes to CT DNA with the dinuclear [tetrakis(diflunisal)bis(N,N-dimethylformamide)dicopper(II)] compound exhibiting the highest binding constant, K_b. Intercalative binding mode may also be concluded using cyclic voltammetry and solution viscosity measurements of the complexes in the presence of CT DNA. Competitive studies with ethidium bromide (EB) indicate that the complexes can displace the DNA-bound EB suggesting competition with EB. Diflunisal and its complexes exhibit good binding propensity to human or bovine serum albumin protein showing relatively high binding constant values.     

Nickel-quinolones interaction. Part 1 - Nickel(II) complexes with the antibacterial drug sparfloxacin: Structure and biological properties

The mononuclear nickel(II) complexes with the third-generation quinolone antibacterial agent sparfloxacin in the absence or presence of nitrogen donor heterocyclic ligands (1,10-phenanthroline or 2,2′-bipyridine) have been synthesized and characterized. The experimental data suggest that sparfloxacin acts as deprotonated bidentate ligand coordinated to Ni(II) ion through the ketone and carboxylato oxygens. The crystal structure of (1,10-phenanthroline)bis(sparfloxacinato) nickel(II), 2 has been determined by X-ray crystallography. The cyclic voltammograms of the complexes recorded in dmso solution and in 1/2 dmso/buffer (containing 150 mM NaCl and 15 mM trisodium citrate at pH 7.0) solution have shown that in the presence of CT DNA they can bind to CT DNA by the intercalative binding mode. UV study of the interaction of the complexes with calf-thymus DNA (CT DNA) has shown that the complexes can bind to CT DNA and 2 exhibits the highest binding constant to CT DNA. Competitive study with ethidium bromide (EB) has shown that the complexes can displace the DNA-bound EB indicating that they bind to DNA in strong competition with EB for the intercalative binding site. The antimicrobial activity of the complexes has been tested on three different microorganisms and has revealed that the inhibition provided by the complexes is slightly decreased in comparison to free sparfloxacin. The complexes exhibit good binding propensity to human and bovine serum albumin proteins having relatively high binding constant values.     

Biological evaluation of cobalt(II) complexes with non-steroidal anti-inflammatory drug naproxen

Cobalt(II) complexes with the non-steroidal anti-inflammatory drug naproxen in the presence or absence of nitrogen-donor heterocyclic ligands (pyridine, 2,2′-bipyridine or 1,10-phenanthroline) have been synthesized and characterized with physicochemical and spectroscopic techniques. The deprotonated naproxen acts as monodentate ligand coordinated to Co(II) ion through a carboxylato oxygen. The crystal structure of [bis(aqua)bis(naproxenato)bis(pyridine)cobalt(II)], 2 has been determined by X-ray crystallography. The EPR spectrum of complex 2 in frozen solution reveals that it retains its structure. UV study of the interaction of the complexes with calf-thymus DNA (CT DNA) has shown that the complexes can bind to CT DNA and [(2,2′-bipyridine)bis(methanol)bis(naproxenato)cobalt(II)] exhibits the highest binding constant to CT DNA. The cyclic voltammograms of the complexes recorded in DMSO solution and in the presence of CT DNA in 1/2 DMSO/buffer (containing 150 mM NaCl and 15 mM trisodium citrate at pH 7.0) solution have shown that they can bind to CT DNA by the intercalative binding mode which has also been verified by DNA solution viscosity measurements. Competitive study with ethidium bromide (EB) has shown that the complexes can displace the DNA-bound EB indicating that they bind to DNA in strong competition with EB. Naproxen and its cobalt(II) complexes exhibit good binding propensity to human or bovine serum albumin proteins having relatively high binding constant values. The antioxidant activity of the compounds has been evaluated indicating their high scavenging activity against hydroxyl free radicals and superoxide radicals.     

Zinc complexes of the antibacterial drug oxolinic acid: Structure and DNA-binding properties

The neutral mononuclear zinc complexes with the quinolone antibacterial drug oxolinic acid in the absence or presence of a nitrogen donor heterocyclic ligand 2,2′-bipyridine or 1,10-phenanthroline have been synthesized and characterized. The experimental data suggest that oxolinic acid is on deprotonated mode acting as a bidentate ligand coordinated to the metal ion through the ketone and one carboxylato oxygen atoms. The crystal structures of (chloro)(oxolinato)(2,2′-bipyridine)zinc(II), 2, and bis(oxolinato)(1,10-phenanthroline)zinc(II), 3, have been determined with X-ray crystallography. The biological activity of the complexes has been evaluated by examining their ability to bind to calf-thymus DNA (CT DNA) with UV and fluorescence spectroscopies. UV studies of the interaction of the complexes with DNA have shown that they can bind to CT DNA and the DNA-binding constants have been calculated. Competitive studies with ethidium bromide (EB) have shown that complex 3 exhibits the ability to displace the DNA-bound EB indicating that it binds to DNA in strong competition with EB.     

Metal complexes of the third-generation quinolone antimicrobial drug sparfloxacin: Structure and biological evaluation

Five metal complexes of the third-generation quinolone antimicrobial agent sparfloxacin with Fe³⁺, VO²⁺, Mn²⁺, Ni²⁺ and have been prepared and characterized with physicochemical and spectroscopic techniques. In these complexes, sparfloxacin acts as a bidentate deprotonated ligand bound to the metal through the ketone oxygen and a carboxylate oxygen. The complexes are six-coordinate with distorted octahedral geometry. For VO(sparfloxacinato)₂(H₂O) the axial position, trans to the vanadyl oxygen, is occupied by a ketone oxygen atom. Molecular mechanics calculations have been performed in order to propose a model for the structure of each complex. The antimicrobial activity of the complexes has been tested against three microorganisms showing that they exhibit lower activity than free sparfloxacin. UV spectroscopic titration with calf-thymus DNA (CT DNA) has shown that the complexes can bind to CT DNA and the binding constants to CT DNA have been calculated. The cyclic voltammograms of the complexes in the presence of CT DNA have shown that they bind to CT DNA probably by the intercalative binding mode. Fluorescence competitive studies with ethidium bromide (EB) have revealed the ability of the complexes to displace the DNA-bound EB. The complexes exhibit good binding propensity to human and bovine serum albumin proteins having relatively high binding constant values.     

Characterization and DNA-interaction studies of 1,1-dicyano-2,2-ethylene dithiolate Ni(II) mixed-ligand complexes with 2-amino-5-methyl thiazole, 2-amino-2-thiazoline and imidazole. Crystal structure of [Ni(i-MNT)(2a-5mt)2]

A series of mixed-ligand neutral nickel(II) complexes of the general formula [Ni(i-MNT)(2a-5mt)₂] (1), [Ni(i-MNT)(2a-2tzn)₂] (2) and [Ni(i-MNT)(Im)₂] (3), [where i-MNT^2? = the dianion of 1,1-dicyano-2,2-ethylenedithiolate, 2a-5mt = 2-amino-5-methyl thiazole, 2a-2tzn = 2-amino-2-thiazoline and Im = imidazole] were prepared and characterized with elemental analyses, spectroscopic (IR, UV–vis) methods, magnetic susceptibility, molar conductivity and cyclic voltammetry measurements. The magnetic data, the electronic spectra and the electrical conductivity measurements indicated mononuclear neutral complexes with square-planar geometry. The X-ray analysis of [Ni(i-MNT)(2a-5mt)₂] shows the nickel atom being fourfold coordinated with the two sulfur atoms of the dithiolate (i-MNT) ligand and the endocyclic nitrogen atoms from the two 2a-5mt ring giving rise to a slightly distorted square-planar arrangement. The cyclic voltammograms of the complexes have been recorded and the corresponding redox potentials have been estimated. The DNA-binding studies of the complexes has been evaluated by examining their ability to bind to calf-thymus DNA (CT DNA) with UV spectroscopy and cyclic voltammetry. Both studies have shown that the complexes can bind to CT-DNA by the intercalative and the electrostatic binding mode. Competitive binding studies with ethidium bromide (EB) with fluorescence spectroscopy have also shown that the complexes exhibit the ability to displace the DNA-bound EB indicating that they can bind to DNA in strong competition with EB.     

DNA-binding and photocleavage studies of mixed polypyridyl ruthenium(II) complexes with calf thymus DNA

New mixed polypyridyl {NMIP = 2′-(2″-nitro-3″,4″-methylenedioxyphenyl)imidazo-[4′,5′-f][1,10]-phenanthroline, dmb = 4,4′-dimethyl-2,2′-bipyridine, bpy = 2,2′-bipyridine} ruthenium(II) complexes [Ru(dmb)₂(NMIP)]²⁺ (1) and [Ru(bpy)₂(NMIP)]²⁺ (2) have been synthesized and characterized. The binding of these complexes to calf thymus DNA (CT-DNA) has been investigated with spectroscopic methods, viscosity and electrophoresis measurements. The experimental results indicate that both complexes could bind to DNA via partial intercalation from the minor/major groove. In addition, both complexes have been found to promote the single-stranded cleavage of plasmid pBR 322 DNA upon irradiation. Under comparable experimental conditions compared with [Ru(phen)₂(NMIP)]²⁺, during the course of the dialysis at intervals of time, the CD signals of both complexes started from none, increased to the maximum magnitude, then no longer changed, and the activity of effective DNA cleavage dependence upon concentration degree lies in the following order: [Ru(phen)₂NMIP]²⁺ > complex 2 > complex 1.     

DNA-binding and photocleavage studies of [Ru(phen)2(NMIP)]

A novel ligand 2′-(2″-nitro-3″,4″-methylenedioxyphenyl)imidazo[4′,5′-f][1,10]-phenanthroline (NMIP) and its complex [Ru(phen)₂(NMIP)]²⁺ have been synthesized and characterized by mass spectroscopy, ¹H NMR and cyclic voltammetry. Binding of the complex with calf thymus DNA (CT DNA) has been investigated by spectroscopic methods, viscosity and electrophoresis measurements. The experimental results indicate that [Ru(phen)₂(NMIP)]²⁺ binds to DNA via partial intercalative mode and the individual enantiomers of it bind to DNA in different rates. [Ru(phen)₂(NMIP)]²⁺ has also been found to promote cleavage of plasmid pBR 322 DNA from the supercoiled Form I to the open circular Form II upon irradiation.     

Synthesis and structural characterization of three hydrogen-bonding connected supramolecular complexes of nickel, zinc and copper with 1,3-diphenyl-4-(salicylidene hydrazide)-acetyl-pyrazolone-5 and 2,2′-bipyridine

A new set of supramolecular complexes, [Ni(DPAP-SHZ)(2,2′-bipy)CH₃OH] (1), [Zn(DPAP-SHZ)(2,2′-bipy)CH₃OH] (2) and [Cu(DPAP-SHZ)(2,2′-bipy)] · 2CH₂Cl₂ (3) (DPAP-SHZ = 1,3-diphenyl-4-(salicylidene hydrazide)-acetyl-pyrazolone-5, 2,2′-bipy = 2,2′-bipyridine) have been synthesized and characterized by elemental analysis, TG-DTA, IR spectroscopy and X-ray crystallography. The X-ray diffraction analyses of the complexes show that the Ni(II) ion and Zn(II) ion centers are six-coordinated while the Cu(II) ion center is five-coordinated. The three supramolecular complexes contain the same ligands, namely DPAP-SHZ and 2,2′-bipy. However, their hydrogen bonds are significantly different, and this variation apparently is responsible for the dissimilar structures of the three supramolecular complexes.     

Mononuclear metal complexes with ciprofloxacin: Synthesis, characterization and DNA-binding properties

Five novel metal complexes of the quinolone antibacterial agent ciprofloxacin with Mn²⁺, Fe³⁺, Co²⁺, Ni²⁺ and have been prepared and characterized with physicochemical, spectroscopic and electrochemical techniques. In all these complexes, ciprofloxacin acts as a bidentate deprotonated ligand bound to the metal through the pyridone oxygen and one carboxylate oxygen. The central metal in each complex is six-coordinate and a slightly distorted octahedral geometry is proposed. The lowest energy model structures of the Mn²⁺, Fe³⁺ and complexes have been determined with molecular modeling calculations. The cyclic voltammograms of the complexes have been recorded in dmso solution and in 1/2 dmso/buffer (containing 150 mM NaCl and 15 mM trisodium citrate at pH 7.0) solution and the corresponding redox potentials have been estimated. The biological activity of the complexes has been evaluated by examining their ability to bind to calf-thymus DNA (CT DNA) with UV and fluorescence spectroscopies and cyclic voltammetry. UV studies of the interaction of the complexes with DNA have shown that these compounds can bind to CT DNA. The binding constants of the complexes with CT DNA have also been calculated. The cyclic voltammograms of the complexes in the presence of CT DNA have shown that the complexes can bind to CT DNA by both the intercalative and the electrostatic binding mode. Competitive studies with ethidium bromide (EB) have shown that the complexes exhibit the ability to displace the DNA-bound EB indicating that the complexes bind to DNA probably via intercalation in strong competition with EB for the intercalative binding site.     

Zinc(II) complexes of the second-generation quinolone antibacterial drug enrofloxacin: Structure and DNA or albumin interaction

Zinc mononuclear complexes with the second-generation quinolone antibacterial drug enrofloxacin in the absence or presence of a nitrogen donor heterocyclic ligand 1,10-phenanthroline or 2,2′-bipyridine have been synthesized and characterized. Enrofloxacin is on deprotonated mode acting as a bidentate ligand coordinated to zinc ion through the ketone and a carboxylato oxygen atoms. The crystal structure of bis(enrofloxacinato)(1,10-phenanthroline)zinc(II), 2, has been determined by X-ray crystallography. The biological activity of the complexes has been evaluated by examining their ability to bind to calf-thymus DNA (CT DNA) with UV and fluorescence spectroscopies. UV studies of the interaction of the complexes with DNA have shown that they can bind to CT DNA and the DNA binding constants have been calculated. Competitive studies with ethidium bromide (EB) have shown that the complexes exhibit the ability to displace the DNA-bound EB indicating that they bind to DNA in strong competition with EB for the intercalative binding site. The complexes exhibit good binding propensity to human and bovine serum albumin proteins having relatively high binding constant values.     

Synthesis, crystal structure and spectroscopic behaviors of Co(II) and Cu(II) complexes with Salen-type bisoxime ligands

Two Salen-type ligands (H₂L¹, 4,4′-dichloro-2,2′-[(1,3-propylene)dioxybis(nitrilomethylidyne)]diphenol and H₂L², 4,4′-dinitro-2,2′-[ethylenedioxybis(nitrilomethylidyne)]diphenol) and their corresponding complexes ({[CoL¹(MeOH)]₂(OAc)₂Co} · 2MeOH and [CuL²]₂) have been synthesized and characterized by element analyses, ¹H NMR, FT-IR and UV-Vis spectra, TG-DTA and single crystal X-ray crystallography. Crystallographic data suggests the octahedral geometry for Co(II) complex and square-pyramidal geometry for Cu(II) complex. Furthermore, the fluorescence behavior of Cu(II) complex in DMSO is discussed.     

Synthesis and electrochemical studies of octahedral nickel β-diketonate complexes

The reaction of [Ni(tmhd)₂] and [Ni(dbm)₂] with N-donor chelating ligands in dichloromethane and acetone, respectively, yields the complexes [Ni(tmhd)₂(L-L)] (L-L = 2,2′-bpy 1, phen 2 and dmae 3) and [Ni(dbm)₂(L-L)] (L-L = 2,2′-bpy 4, phen 5, dmae 6). UV-Vis spectroscopy shows very strong bands in the UV region consistent with ligand centred π → π^∗ transitions. The electrochemical studies of 1-6 reveal oxidation to Ni(III). The [Ni(tmhd)₂(L-L)] 1-3 are more easily oxidized by ca. 300 mV and are quasi-reversible whereas for the [Ni(dbm)₂(L-L)] series only complex 6 shows significant reversibility. X-ray crystallographic studies have been conducted in the case of [Ni(dbm)₂(phen)] 5 and [Ni(dbm)₂(dmae)] 6. The structures both show that the nickel metal centre is octahedral with an O₄N₂ coordination environment. In the structures the β-diketonate ligands exhibit a cis-arrangement, with the metal displaced out of the planar chelate ring.     

Mononuclear copper(II) complexes with quinolones and nitrogen-donor heterocyclic ligands: Synthesis, characterization, biological activity and interaction with DNA

The neutral mononuclear copper(II) complexes with the quinolone antibacterial drugs, pipemidic acid and N-propyl-norfloxacin, in the presence or absence of nitrogen-donor heterocyclic ligands, 2,2′-bipyridine, 1,10-phenanthroline or 2,2′-dipyridylamine, have been prepared and characterized spectroscopically. The interaction of copper(II) with the deprotonated quinolone ligand leads to the formation of the neutral mononuclear complexes of the type [Cu(quinolone)₂(H₂O)] (1)–(2) while the presence of the N-donor ligand leads to the formation of the neutral mononuclear complexes of the type [Cu(quinolone)(N-donor)Cl] (3)–(8). In all the complexes, copper(II) is pentacoordinate having a distorted square pyramidal geometry. The electron paramagnetic resonance spectra of 1 and 2 are typical of mononuclear Cu(II) complexes, while for the mixed-ligands complexes 3–8 a mixture of dimeric and monomeric species is indicated. The interaction of the complexes with calf-thymus DNA has been investigated with diverse spectroscopic techniques and has shown that the complexes can be bound to calf-thymus DNA by the intercalative mode. The antimicrobial activity of the complexes has been tested on three different microorganisms. All the complexes show an increased biological activity in comparison to the corresponding free quinolone ligand.     

Chiral ruthenium(II) anthraquinone complexes as dual inhibitors of topoisomerases I and II

Abstract  

DNA topoisomerases (I and II) have been one of the excellent targets in anticancer drug development. Here two chiral ruthenium(II) anthraquinone complexes, Δ- and Λ-[Ru(bpy)₂(ipad)]²⁺, where bpy is 2,2′-bipyridine and ipad is 2-(anthracene-9,10-dione-2-yl)imidazo[4,5-f][1,10]phenanthroline, were synthesized and characterized. As expected, both of the Ru(II) complexes intercalate into DNA base pairs and possess an obviously greater affinity with DNA. Topoisomerase inhibition and DNA strand passage assay confirmed that the two complexes are efficient dual inhibitors of topoisomerases I and II by interference with the DNA religation. In MTT cytotoxicity studies, two Ru(II) complexes exhibited antitumor activity against HeLa, MCF-7, HepG2 and BEL-7402 tumor cell lines. Flow cytometry analysis shows an increase in the percentage of cells with apoptotic morphological features in the sub-G1 phase for Ru(II) complexes. Nuclear chromatin cleavage has also been observed from AO/EB staining assay and alkaline single-cell gel electrophoresis (comet assay). The results demonstrated that Δ- and Λ-[Ru(bpy)₂(ipad)]²⁺ act as dual inhibitors of topoisomerases I and II, and cause DNA damage that can lead to cell cycle arrest and/or cell death by apoptosis.