Synthesis,characterization, DNA and HSA binding studies of isomeric Pd (II) antitumor complexes using spectrophotometry techniques

Two new Palladium(II) isomeric complexes, [Pd (Gly)(Leu)](I) and [Pd (Gly)(Ile)](II), where Gly is glycine, and Leu and Ile are isomeric amino acids (leucine and isoleucine), have been synthesized and characterized by elemental analysis, molar conductivity measurements, FT-IR, ¹H NMR, and UV–Vis. The complexes have been tested for their In vitro cytotoxicity against cancer cell line K₅₆₂ and their binding properties to calf thymus DNA (CT-DNA) and human serum albumin (HSA) have also been investigated by multispectroscopic techniques. Interactions of these complexes with CT-DNA were monitored using gel electrophoresis. The energy transfer from HSA to these complexes and the binding distance between HSA and the complexes (r) were calculated. The results obtained from these studies indicated that at very low concentrations, both complexes effectively interact with CT-DNA and HSA. Fluorescence studies revealed that the complexes strongly quench DNA bound ethidium bromide as well as the intrinsic fluorescence of HSA through the static quenching procedures. Binding constant (K_b), apparent biomolecular quenching constant (k_q), and number of binding sites (n) for CT-DNA and HSA were calculated using Stern–Volmer equation. The calculated thermodynamic parameters indicated that the hydrogen binding and vander Waals forces might play a major role in the interaction of these complexes with HSA and DNA. Thus, we propose that the complexes exhibit the groove binding with CT-DNA and interact with the main binding pocket of HSA. The complexes follow the binding affinity order of I > II with DNA- and II > I with HSA-binding.     

Five novel palladium(II) complexes of 8-hydroxyquinoline and amino acids with hydrophobic side chains: synthesis,characterization, cytotoxicity,DNA- and BSA-interaction studies

Abstract

The side effects and resistance of metal-based anticancer drugs prompted us to synthesis a novel series of five Pd(II) complexes of the type [Pd(8-QO)(AA)]; where 8-QO?=?anion of 8-hydroxyquinoline and AA?=?anions of amino acids having nonpolar aliphatic side chain such as glycine (–H), alanine (–CH₃), valine (–CH(CH₃)₂), leucine (–CH₂–CH(CH₃)₂) and isoleucine (–CH(CH₃)CH₂–CH₃). The complexes have been characterized with the help of FT-IR, UV–Vis, one and two-dimensional ¹H-NMR, elemental analysis and conductivity measurements. On the basis of these characterization data, a four coordinated square planar geometry for all of these complexes have been proposed. The compounds were screened for their in vitro activities against human cancer cell line, MOLT-4 and their 50% inhibition concentration were ascertained by means of MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Since four out of the five newly synthesized compounds were found to be more active than the standard anticancer drug, cisplatin, their detailed interaction with calf thymus DNA (as a target) and bovine serum albumin (BSA) (as a carrier) were also carried out by utilizing absorption spectra, fluorescence spectra and ethidium bromide displacement studies. In these experiments, several binding and thermodynamic parameters were also calculated. These results suggested that hydrogen binding and van der Waals forces play a major role in the interaction between metal complexes with CT-DNA and BSA.

Communicated by Ramaswamy H. Sarma     

Copper (II) and zinc (ii) metal-based salicyl-, furanyl-, thienyl- and pyrrolyl-derived ONNO,NNNO, ONNS & NNNS donor asymmetrically mixed schiff-bases with antibacterial and antifungal potentials

A new series of asymmetric salicyl-, furanyl-, thienyl- and pyrrolyl-derived ONNO, NNNO, ONNS & NNNS donor antibacterial and antifungal Schiff-bases and their copper(II) and zinc(II) metal complexes have been synthesized and characterized. IR spectra indicated the ligands to act as quartdentate towards divalent metal ions via two azomethine-N, deprotonated-O of salicyl, furanyl-O, thienyl-S and/or pyrrolyl-N. The magnetic moments and electronic spectral data suggest octahedral geometry for Cu(II) and Zn(II) complexes. NMR spectral data of the ligands and their diamagnetic zinc(II) complexes well-define their proposed structures/geometries. Elemental analyses data of the ligands and metal complexes agree with their proposed structures/geometries. The synthesized ligands, along with their metal complexes were screened for their antibacterial activity against B. cereus, C. diphtheriae, E. coli, K. pneumoniae, P. mirabilis, P. aeruginosa, S. typhi, S. dysenteriae and S. aureus strains and for in-vitro antifungal activity against T. schoenleinii, C. glabrata, P. boydii, C. albicans, A. niger, M. canis and T. mentagrophytes. The results of these studies show the metal complexes to be more antibacterial/antifungal against one or more species as compared to the uncomplexed ligands. The brine shrimp bioassay was also carried out to study their in-vitro cytotoxic properties. Eight compounds, L₄, (1), (7), (8), (11), (17), (19) and (23) displayed potent cytotoxic activity with LD₅₀ = 1.445 × 10^{? 3}, 1.021 × 10^{? 3}, 7.478 × 10^{? 4}, 8.566 × 10^{? 4}, 1.028 × 10^{? 3}, 9.943 × 10^{? 4}, 8.730 × 10^{? 4} and 1.124 × 10^{? 3} M respectively, against Artemia salina.     

Synthesis,characterization, cytotoxicity,and DNA binding of some new platinum(II) and platinum(IV) complexes with benzimidazole ligands

In this study, two Pt(II) and three Pt(IV) complexes with the structures of [PtL₂Cl₂] (1), [PtL₂I₂] (2), [PtL₂Cl₂(OH)₂] (3), [PtL₂Cl₂(OCOCH₃)₂] (4), and [PtL₂Cl₄] (5) (L = benzimidazole as carrier ligand) were synthesized and evaluated for their in vitro antiproliferative activities against the human MCF-7, HeLa, and HEp-2 cancer cell lines. The influence of compounds 1–5 on the tertiary structure of DNA was determined by their ability to modify the electrophoretic mobility of the form I and II bands of pBR322 plasmid DNA. The inhibition of BamH1 restriction enzyme activity of compounds 1–5 was also determined. In general, it was found that compounds 1–5 were less active than cisplatin and carboplatin against MCF-7 and HeLa cell lines (except for 1, which was found to be more active than carboplatin against the MCF-7 cell line). Compounds 1 and 3 were found to be significantly more active than cisplatin and carboplatin against the HEp-2 cell line.     

Spectral analysis and in vitro cytotoxicity profiles of novel organotin(IV) esters of 2-maleimidopropanoic acid

Six novel triorganotin(IV) 2-maleimidopropanoato complexes: R₃SnOCOCH₃(CH)(COCH)₂, (R: Me(1), Et(2), n-Pr(3), n-Bu(4), Ph(5), Bz(6) have been synthesized. Their solid-state configuration has been determined by FT IR and ^119mSn Mössbauer spectroscopy. The tin(IV) atom is five-coordinated in all the complexes with 2-maleimidopropanoic acid behaving as a monoanionic bidentate ligand coordinating the tin(IV) atom through a chelating or bridging carboxylate group. The solution-state configuration has been elucidated by means of ¹H-, ¹³C- and ¹¹⁹Sn-NMR spectroscopy which assigned a tetrahedron. Elemental analysis and FAB MS data also supported a 1:1 metal to ligand stoichiometry. The title complexes have been screened in vitro for anti-tumour, anti-fungal, anti-leishmanial and urease inhibition activities and displayed promising results.     

Density functional theory molecular modelling,DNA interactions,antioxidant, antimicrobial,anticancer and biothermodynamic studies of bioactive water soluble mixed ligand complexes

A novel series of bioactive water soluble mixed ligand complexes (1–5) [M^II(L)(phen)AcO]. nH₂O {where M?=?Cu (1) n?=?2; Co (2), Mn (3), Ni (4), n?=?4 and Zn (5) n?=?2} were synthesized from 2-(2-Morpholinoethylimino) methyl)phenol Schiff base ligand (LH), 1, 10-phenanthroline and metal(II) acetate salt in a 1:1:1 stoichiometric ratio and characterized by several spectral techniques. The obtained analytical and spectral data suggest the octahedral geometry around the central metal ion. Density functional theory calculations have been further supportive to explore the optimized structure and chemical reactivity of these complexes from their frontier molecular orbitals. Gel electrophoresis result indicates that complex (1) manifested an excellent DNA cleavage property than others. The observed binding constants with free energy changes by electronic absorption technique and DNA binding affinity values by viscosity measurements for all compounds were found in the following order (1)?>?(2)?>?(4)?>?(5)?>?(3) > (LH). The binding results and thermodynamic parameters are described the intercalation mode. In vitro antioxidant properties disclose that complex (1) divulges high scavenging activity against DPPH^?, ^?OH, O₂^?? NO^?, and Fe³⁺. The antimicrobial reports illustrate that the complexes (1–5) were exhibited well defined inhibitory effect than ligand (LH) against the selected different pathogenic species. The observed percentage growth inhibition against A549, HepG2, MCF-7, and NHDF cell lines suggest that complex (1) has exhibited superior anticancer potency than others. Thus, the complex (1) may contribute as potential anticancer agent due to its unique interaction mode with DNA.GRAPHICAL ABSTRACT

Communicated by Ramaswamy H. Sarma     

A novel proton transfer salt of 2-amino-6-sulfamoylbenzothiazole and its metal complexes: the evaluation of their inhibition effects on human cytosolic carbonic anhydrases

A novel proton transfer compound (SMHABT)⁺(HDPC)^? (1) obtained from 2-amino-6-sulfamoylbenzothiazole (SMABT) and 2,6-pyridinedicarboxylic acid (H₂DPC) and its Fe(III), Co(II), Ni(II) complexes (2–4), and Fe(II) complex of SMABT (5) have been prepared and characterized by spectroscopic techniques. Additionally, single crystal X-ray diffraction techniques were applied to complexes (2–4). All complexes (2–4) have distorted octahedral conformations and the structure of 5 might be proposed as octahedral according to spectral and analytical results. All compounds, including acetazolamide (AAZ) as the control compound, were also evaluated for their in vitro inhibition effects on human hCA I and hCA II for their hydratase and esterase activities. The synthesized compounds have remarkable inhibitory activities on hCA I and hCA II. Especially, the inhibition potentials of the salt and the metal complexes (1–5) are comparable with AAZ. Inhibition data have been analyzed by using a one-way analysis of variance for multiple comparisons (p?相似文献   

In-vitro antibacterial,antifungal and cytotoxic properties of metal-based furanyl derived sulfonamides

A new series of antibacterial and antifungal furanyl-derived sulfonamides and their cobalt (II), copper (II), nickel (II) and zinc (II) metal complexes have been synthesized, characterized and screened for their in-vitro antibacterial activity against four Gram-negative (Escherichia coli, Shigella flexneri, Pseudomonas aeruginosa and Salmonella typhi) and two Gram-positive (Bacillus subtilis and Staphylococcus aureus) bacterial strains and, for in-vitro antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata. The results of these studies revealed that all compounds showed significant to moderate antibacterial activity. However, the zinc (II) complexes were found to be comparatively much more active as compared to the others. For antifungal activity generally, compounds (22) and (24) showed significant activity against Escherichia coli (a), (6) against Shigella flexeneri (b), (16) and (22) against Pseudomonas aeruginosa (c), (14) and (16) against Salmonella typhi (d), (9) against Staphylococcus aureus (e) and, (14) and (16) against Bacillus subtilis (f) fungal strains. The brine shrimp (Artemia salina) bioassay was also carried out to study their in-vitro cytotoxic properties. Only three compounds, (6), (10) and (23) displayed potent cytotoxic activity with LD₅₀ = 1.8535 × 10^{? 4}, 1.8173 × 10^{? 4} and 1.9291 × 10^{? 4} respectively.     

New binary copper(II) complexes containing intercalating ligands: DNA interactions,an unusual static quenching mechanism of BSA and cytotoxic activities

New binary copper(II) complexes – [Cu(4-mphen)₂(NO₃)]NO₃·H₂O (1), [Cu(5-mphen)₂ (NO₃)]NO₃·H₂O (2), the known complex [Cu(dmphen)₂(NO₃)]NO₃ (3) and [Cu(tmphen)₂ (NO₃)]NO₃·H₂O (4) - (4-mphen: 4-methyl-1,10-phenanthroline, 5-mphen: 5-methyl-1,10-phenanthroline, dmphen: 4,7-dimethyl-1,10-phenanthroline, tmphen: 3,4,7,8-tetramethyl-1,10-phenanthroline), have been synthesized and characterized by CHN analysis, ESI-MS, FTIR and single-crystal X-ray diffraction techniques. Interaction of these complexes with calf thymus DNA (CT-DNA) has been investigated by absorption spectral titration, ethidium bromide (EB) and Hoechst 33,258 displacement assay and thermal denaturation measurement. These complexes cleaved pUC19 plasmid DNA in the absence and presence of an external agent. Notably, in the presence of H₂O₂ as an activator, the cleavage abilities of these complexes are obviously enhanced at low concentration. Addition of hydroxyl radical scavengers like DMSO shows significant inhibition of the DNA cleavage activity of these complexes. BSA quenching mechanism was investigated with regard to the type of quenching, binding constant, number of binding locations and the thermodynamic parameters. The experimental results suggested that the probable quenching mechanism was an unusual static process and hydrophobic forces play a dominant role. The CT-DNA and BSA binding efficiencies of these complexes follow the order: 4 > 3 > 1 > 2. Furthermore, in vitro cytotoxicities of these complexes on tumor cells lines (Caco-2, MCF-7 and A549) and healthy cell line (BEAS-2B) showed that these complexes exhibited anticancer activity with low IC₅₀ values. The effect of hydrophobicity of the methyl-substituted phenanthrolines on DNA and protein binding activities of these complexes is discussed.     

Synthesis, structural characterization and in vitro cytotoxicity and anti-bacterial activity of some copper(I) complexes with N,N′-disubstituted thioureas

A series of copper(I) complexes of N,N′-disubstituted thioureas, [C₆H₅CONHCSNHR]Cu(I)Cl where R = C₆H₅ (1a), 2-ClC₆H₄ (2a), 3-ClC₆H₄ (3a), 4-ClC₆H₄ (4a), 2,3-Cl₂C₆H₃ (5a), 2,4-Cl₂C₆H₃ (6a), 2,5-Cl₂C₆H₃ (7a), 2,6-Cl₂C₆H₃ (8a), 3,4-Cl₂C₆H₃ (9a) and 3,5-Cl₂C₆H₃ (10a) have been synthesized. These complexes (1a–10a) have been characterized by elemental analyses, IR, ¹H and ¹³C NMR spectroscopy, cyclic voltammetry and single crystal XRD for 1a and 8a, and for ligand 7. The X-ray crystal structures reveal that the complexes 1a and 8a are mononuclear in the solid state in which the copper atoms adopt a distorted tetrahedral geometry. In both the cases, the neutral N,N′-disubstituted thiourea ligands have been coordinated to the Cu(I) through the sulphur atom in a terminal mode. The complexes have been screened for their in vitro cytotoxic activity in human cell lines carcinomas A498 (Renal), EVSA-T (Breast), H226 (Lung), IGROV (Ovarian), M19 (Melanoma-Skin), MCF-7 (Breast) and WIDR (Colon). They show a moderate cytotoxicity against these seven human cancer cell lines comparable to that of the less active standard chemotherapeutic drugs used for comparison. They were also screened for their anti-bacterial activity and were found less active than the standard drug Imipenem.     

Rhodium(III) and iridium(III) complexes with 1,2-naphthoquinone-1-oximate as a bidentate ligand: synthesis,structure, and biological activity

The synthesis and characterization of three novel iridium(III) complexes and one rhodium(III) complex with 1-nitroso-2-naphthol (3) chelating as a 1,2-naphthoquinone-1-oximato ligand are described. The reaction of μ₂-halogenido-bridged dimers [(η⁵-C₅Me₅)IrX₂]₂ [X is Cl (1a), Br (1b), I (1c)] and [(η⁵-C₅Me₅)RhCl₂]₂ (2a) with 3 in CH₂Cl₂ yields the mononuclear complexes (η⁵-C₅Me₅)IrX(η²-C₁₀H₆N₂O) (4a, 4b, 4c) and (η⁵-C₅Me₅)RhCl(η²-C₁₀H₆N₂O) (5a). All compounds were characterized by their ¹H and ¹³C NMR, IR, and mass spectra, UV/vis spectra were recorded for 4a and 5a. The X-ray structure analyses revealed a pseudo-octahedral “piano-stool” configuration for the metals with bidentate coordination through oximato-N and naphthoquinone-O, forming a nearly planar five-membered metallacycle. The metal complexes 4a and 5a were evaluated in respect to their cytotoxicity and binding affinity toward double-stranded DNA. As determined in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, both exerted a much stronger cytotoxic effect toward HeLa and HL60 cancer cell lines than did cisplatin. The remarkable cytotoxicity of the compounds tested may be attributed to necrosis, rather than to apoptosis, as it is evidenced by the caspase-3/7 activation assay. No clear evidence was found for interaction with double-stranded DNA. The melting experiments showed no significant differences between thermodynamic parameters of intact DNA and DNA incubated with 3, 4a, or 5a, although these derivatives altered DNA recognition by the BamHI restriction enzyme. Therefore, the screened iridium and rhodium complexes 4a and 5a may still be interesting as potential anticancer drugs owing to their high cytotoxicity toward cancer cell lines, whereas they do not modify DNA in a way similar to that of cisplatin.     

Synthesis,conformation and biological activity of centrally modified pseudopeptidic analogues of For-Met-Leu-Phe-OMe

Summary. For-Met-βAlaψ[CSNH]-Phe-OMe (3), For-Met-βAlaψ[CH₂NH]-Phe-OMe (5), For-Met-NH-pC₆H₄-SO₂-Phe-OMe (8a), For-Met-NH-mC₆H₄-SO₂-Phe-OMe (8b) and the corresponding N-Boc precursors (2, 4, 7a, b) have been synthesized and their activity towards human neutrophils has been evaluated in comparison with that shown by the reference tripeptide For-Met-Leu-Phe-OMe (fMLF-OMe). Chemotaxis, lysozyme release and superoxide anion production have been measured. ¹H NMR titration experiments and IR spectra have been discussed in order to ascertain the preferred solution conformation adopted by the tripeptide 3 with particular reference to the presence of a folded conformation centred at the centrally positioned thionated β-residue.     

Synthesis, spectroscopic characterization and radiosensitizing properties of acetato-bridged copper(II) complexes with 5-nitroimidazole drugs

Three novel acetato-bridged dinuclear copper(II) complexes with 5-nitroimidazoles (CuAcNtrim) and the known copper-acetato-metronidazole have been prepared by an environment-friendly route and spectroscopically characterized. The CuAcNtrim compounds of formula [Cu₂(μ-O₂CCH₃)₄Ntrim₂], where Ntrim = metronidazole (1), secnidazole (2), tinidazole (3) or nimorazole (4), exhibit dimeric copper-acetato paddle-wheel structures with Ntrim axial ligands coordinated to copper(II) ions through the N₃ atoms of the imidazole rings. EPR data indicate antiferromagnetic behavior for this novel series of copper complexes. The constant coupling has been found to decrease along with the increasing of basicity of the Ntrim axial ligand. The CuAcNtrim complexes and the correspondent Ntrim parent drugs have shown radiosensitizer properties for Hep2 (human larynx cancer) cell line in vitro. The best enhancement of radiosensitizer activity upon coordination of the Ntrim drug to copper(II) has been found for the nimorazole compound which has the strongest Cu-Ntrim bond and exhibits the highest lipophilicity within the series of CuAcNtrim complexes.     

Water-soluble titanocene complexes with sulfur-containing aminoacids: synthesis, spectroscopic, electrochemical and Ti(IV)–transferrin interaction studies

Three new water soluble titanocene–aminoacid complexes have been synthesized via the reaction of Cp₂TiCl₂ and two equivalents of aminoacid (L) in methanol, affording [Cp₂TiL₂]Cl₂, L=L-cysteine (2), D-penicillamine (3) and L-methionine (4). These complexes have been characterized by ¹H, IR and UV-Vis spectroscopies, elemental analysis and cyclic voltammetry. Kinetic studies of ligand hydrolysis have been monitored at low pH using UV-Vis and ¹H NMR spectroscopies to assess their stability in aqueous solution. At low pH, aminoacid ligands are lost one order of magnitude faster than cyclopentadienyl. However, at physiological pH, in Tris buffer solution, the complexes decompose rapidly to form an insoluble titanium compound. The affinity of these complexes to apo-transferrin was also investigated to elucidate how the ancillary aminoacid ligands affect the titanium intake by apo-transferrin.Electronic Supplementary Material Supplementary material is available for this article at     

Cd(II) and Cu(II) complexes of polydentate Schiff base ligands: synthesis, characterization, properties and biological activity

We report the synthesis of the Schiff base ligands, 4-[(4-bromo-phenylimino)-methyl]-benzene-1,2,3-triol (A₁), 4-[(3,5-di-tert-butyl-4-hydroxy-phenylimino)-methyl]-benzene-1,2,3-triol (A₂), 3-(p-tolylimino-methyl)-benzene-1,2-diol (A₃), 3-[(4-bromo-phenylimino)-methyl]-benzene-1,2-diol (A₄), and 4-[(3,5-di-tert-butyl-4-hydroxy-phenylimino)-methyl]-benzene-1,3-diol (A₅), and their Cd(II) and Cu(II) metal complexes, stability constants and potentiometric studies. The structure of the ligands and their complexes was investigated using elemental analysis, FT-IR, UV-Vis, ¹H and ¹³C NMR, mass spectra, magnetic susceptibility and conductance measurements. In the complexes, all the ligands behave as bidentate ligands, the oxygen in the ortho position and azomethine nitrogen atoms of the ligands coordinate to the metal ions. The keto-enol tautomeric forms of the Schiff base ligands A₁-A₅ have been investigated in polar and non-polar organic solvents. Antimicrobial activity of the ligands and metal complexes were tested using the disc diffusion method and the strains Bacillus megaterium and Candida tropicalis.Protonation constants of the triol and diol Schiff bases and stability constants of their Cu²⁺ and Cd²⁺ complexes were determined by potentiometric titration method in 50% DMSO-water media at 25.00 ± 0.02 °C under nitrogen atmosphere and ionic strength of 0.1 M sodium perchlorate. It has been observed that all the Schiff base ligands titrated here have two protonation constants. The variation of protonation constant of these compounds was interpreted on the basis of structural effects associated with the substituents. The divalent metal ions of Cu²⁺ and Cd²⁺ form stable 1:2 complexes with Schiff bases.The Schiff base complexes of cadmium inhibit the intense chemiluminescence reaction in dimethylsulfoxide (DMSO) solution between luminol and dioxygen in the presence of a strong base. This effect is significantly correlated with the stability constants K_CdL of the complexes and the protonation constants K_OH of the ligands; it also has a nonsignificant association with antibacterial activity.     

Synthesis,Characterization, Cellular Uptake,Apoptosis, Cytotoxicity,Dna-Binding,and Antioxidant Activity Studies of Ruthenium(II) Complexes

Two new ruthenium(II) polypyridyl complexes [Ru(dmb)₂(HECIP)](ClO₄)₂ (1) (HECIP = N-ethyl-4-[(1,10)-phenanthroline(5,6-f)imidazol-2-yl]carbazole, dmb = 4,4’-dimethyl-2,2’-bipyridine) and [Ru(dmp)₂(HECIP)](ClO₄)₂ (2) (dmp = 2,9-dimethyl-1,10-phenanthroline) have been synthesized and characterized. The DNA-binding behaviors of the two complexes were investigated by absorption spectra, viscosity measurements, and photoactivated cleavage. The DNA-binding constants for complexes 1 and 2 were determined to be 8.03 (± 0.12) × 10⁴ M^?1 (s = 1.62) and 2.97 (± 0.15) × 10⁴ M^?1 (s = 1.82), respectively. The results suggest that these complexes interact with DNA through intercalative mode. The photocleavage of pBR322 DNA by Ru(II) complexes was investigated. The cytotoxicity of complexes 1 and 2 has been evaluated by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide)] method. Complex 1 shows higher anticancer potency than 2 against the four tumor cell lines. Apoptosis and cellular uptake were investigated. The antioxidant activities of the ligand and these complexes were also performed.     

Macrocyclic complexes: synthesis,characterization, antitumor and DNA binding studies

Abstract

The present paper deals with the synthesis of novel macrocyclic complexes of the type [MLX]X, where [(M?=?Co(II) (1), and Ni(II) (2) X?=?(Cl₂)]. The complexes are synthesized by the reaction of ligand(L)diquinolineno[1,3,7,9]tetraazacyclododecine-7,15-ethane(14H,16H)-benzene with the corresponding metal salts. The synthesized complexes are thoroughly characterized by elemental analysis, FT-IR, ¹H-NMR, Mass and electronic spectra. The complexes (1) and (2) were evaluated for in vitro cytotoxicity against human breast adenocarcinoma cell (MCF-7). MTT cytotoxicity studies shows both the complexes are most effective. The binding properties of these complexes with calf thymus-DNA were studied by absorption, emission spectra, viscosity measurements, and thermal denaturation studies. On binding to CT-DNA, the absorption spectrum undergoes bathochromic and hypochromic shifts. The absorption spectral results indicate that the intrinsic binding constant (K_b) are 4.8?×?10⁵?M^?1 for (1) and 3.9?×?10⁵?M^?1 for (2) respectively, suggesting that complex (1) binds more strongly to CT-DNA than complex (2). The viscosity measurement results revealed the viscosity of sonicated rod like DNA fragments increased when the complex was added to the solution of CT-DNA. The synthesized ligand and its metal complexes are screened for antibacterial and antifungal activities.     

Synthesis,characterization, redox behavior,DNA and protein binding and antibacterial activity studies of ruthenium(II) complexes of bidentate schiff bases

Two new ruthenium(II) complexes of Schiff base ligands (L) derived from cinnamaldehyde and ethylenediamine formulated as [Ru(L)(bpy)₂](ClO₄)₂, where L¹ = N,N’-bis(4-nitrocinnamald-ehyde)ethylenediamine and L² = N,N’-bis(2-nitrocinnamaldehyde)-ethylenediamine for complex 1 and 2, respectively, were isolated in pure form. The complexes were characterized by physicochemical and spectroscopic methods. The electrochemical behavior of the complexes showed the Ru(III)/Ru(II) couple at different potentials with quasi-reversible voltammograms. The interaction of the complexes with calf thymus DNA (CT-DNA) using absorption, emission spectral studies and electrochemical techniques have been used to determine the binding constant, K_b and the linear Stern–Volmer quenching constant, K_SV. The results indicate that the ruthenium(II) complexes interact with CT-DNA strongly in a groove binding mode. The interactions of bovine serum albumin (BSA) with the complexes were also investigated with the help of absorption and fluorescence spectroscopy tools. Absorption spectroscopy proved the formation of a ground state BSA-[Ru(L)(bpy)₂](ClO₄)₂ complex. The antibacterial study showed that the Ru(II) complexes (1 and 2) have better activity than the standard antibiotics but weak activity than the ligands.     

Investigation on the pharmacological profile of antimony(III) complexes with hydroxyquinoline derivatives: anti-trypanosomal activity and cytotoxicity against human leukemia cell lines

Complexes [Sb(QN)₂Cl] (1), [Sb(QC)₂Cl] (2) and [Sb(QI)₂Cl] (3) were obtained with 8-hydroxyquinoline (HQN), 5-chloro-8-hydroxyquinoline (HQC) and 5-chloro-7-iodo-8-hydroxyquinoline (clioquinol, HQI). The quinoline derivatives and their antimony(III) complexes were evaluated for their anti-trypanosomal activity as well as for their cytotoxicity against HL-60 and Jurkat human leukemia cell lines. Upon coordination to antimony(III) the anti-trypanosomal activity of HQC and HQI increases, the highest improvement being observed for complex (3), which was the most active among all studied compounds against both epimastigote and trypomastigote forms of Trypanosoma cruzi. All quinoline derivatives proved to be cytotoxic against both leukemia cell lineages. Upon coordination to antimony(III) the cytotoxicity of HQN improved against Jurkat leukemia cells. While SbCl₃ proved to be cytotoxic against HL-60 cells, it was not active against Jurkat cells. However, its coordination to the quinoline derivatives resulted in complexes with significant cytotoxicity against Jurkat cells.     

Synthesis and crystal structures of cobalt(II), cadmium(II), and zinc(II) complexes of 4-nitro phenylcyanamide: enhancing the biological properties through bound to human serum albumin

Metal complexes of the type [Co(phen)₂(4-NO₂pcyd)₂].CH₃OH, 1, [Zn(phen)₂(4-NO₂pcyd)₂].CH₃OH, 2, [Cd(phen)₂(4-NO₂pcyd)₂], and 3, (phen?=?1,10-phenanthroline, 4-NO₂pcyd?=?4-nitro phenylcyanamide) have been studied. The synthesis, characterization, and the biological activities of complexes 1-3 have been investigated. The geometries of complexes 1-3 were confirmed by single-crystal X-ray crystallography. The interactions of complexes 1-3 with human serum albumin (HSA) were studied using fluorescence and circular dichroism spectroscopy. The thermodynamic studies have showed the reaction for the binding of complexes 1-3 with HSA is hydrophobic (ΔH_0???0 and ΔS₀ > 0). The in vitro cytotoxic potential of complexes 1-3 and their complexes with HSA were examined. The complexes 1-3 with HSA enhance about 3-fold cytotoxicity in cancer cells lines.