Crystal structures, DNA interaction and antiproliferative activities of the cobalt(II) and zinc(II) complexes of 2-amino-1,3,4-thiadiazole with demethylcantharate

Preparation, Characterization and In Vitro Biological Activities of New Diphenylsulphone Derived Schiff Base Ligands and Their Co(II) Complexes

The present work describes the chemical preparation of Schiff bases derived from 4,4'-diaminodiphenyl sulfone (L₁-L₅) and their Co(II) metal complexes. The evaluation of antimicrobial and anticancer activities against MCF-7 cell line and human lung cancer cell line A-549 was performed. The aforementioned synthesized compounds are characterized by spectroscopic techniques and elemental analysis confirms successful synthesis. The results from the above analytical techniques revealed that the complexes are in an octahedral geometry. The antimicrobial activity of the synthesized Schiff base ligands and their metal complexes under study was carried out by using the agar well diffusion method. The ligand and complex interactions for biological targets were predicted using molecular docking and high binding affinities. Further, the anticancer properties of the synthesized compounds are performed against the MCF-7 cell line and human lung cancer cell line A-549 using adriamycin as the standard drug.

Selective cytotoxicity and antifungal properties of copper(II) and cobalt(II) complexes with imidazole-4-acetate anion or 1-allylimidazole

The physicochemical properties of metal complexes determine their potential applications as antitumor agents. In this study, the antitumor properties of mononuclear cobalt(II) and copper(II) coordination compounds (stoichiometry: [Co(iaa)₂(H₂O)₂]·H₂O (iaa = imidazole-4-acetate anion), [Co(1-allim)₆](NO₃)₂ (1-allim = 1-allylimidazole), [Cu(iaa)₂H₂O] and [Cu(1-allim)₄(NO₃)₂]) and their ligands have been evaluated on human lung carcinoma A549 cells and normal bronchial BEAS-2B cells. Designing the chemical structure of new antitumor agents the possible interactions with macromolecules such as DNA or proteins should be take into account. PCR gene tlr4 product served as DNA model, whereas lysozyme and phage-derived endolysin (both peptidoglycan degrading enzymes) were applied as protein/enzyme model. The interactions were analysed using PCR-HRM and circular dichroism, FT-IR, spectrophotometry, respectively. Additionally, the antimicrobial properties of the complexes at a non-cytotoxic concentration were analyzed against S. aureus, E. coli, P. aeruginosa and C. albicans strains. The results obtained in this study showed the selective cytotoxicity of metal complexes, mainly [Cu(1-allim)₄(NO₃)₂] towards tumor cells. From all tested compounds, only [Co(iaa)₂(H₂O)₂]^.H₂O non-covalently interacts with DNA. Cu(II) and Co(II) complexes did not affect the secondary conformation of tested proteins but modified the hydrolytic activity of enzymes (lysozyme and endolysin). Moreover, only [Co(iaa)₂(H₂O)₂]^.H₂O exhibited the antifungal properties. In conclusion, Co(II) and Cu(II) metal complexes bearing two imidazole-4-acetate ligands seemed to be promising antitumor and antifungal agents for future drug design and application.

Synthesis and characterization of new unsymmetrical Schiff base Zn (II) and Co (II) complexes and study of their interactions with bovin serum albumin and DNA by spectroscopic techniques

Two novel tetra-coordinated Cobalt(II) and Zinc (II) chelate series with the general formula of [Co (L)·2H₂O] (1) and [Zn (L)] (2) [L=N-2-hydroxyacetophenon-N'-2-hydroxynaphthaldehyde-1,2 phenylenediimine)] with biologically active Schiff base ligands were synthesized and recognized by elemental analysis and multi-nuclear spectroscopy (IR and ¹H and ¹³C NMR); then, their biological activities including DNA and protein interactions were studied. The interaction of the synthesized compounds with bovine serum albumin (BSA) was investigated via fluorescence spectroscopy, showing the affinity of the complexes for these proteins with relatively high binding constant values and the changed secondary BSA structure in the presence of the complexes. The interaction of these compounds with CT-DNA was considered by UV-Vis technique, emission titration, viscosity measurements, helix melting methods, and circular dichroism (CD) spectroscopy, confirming that the complexes were bound to CT-DNA by the intercalation binding mode. Furthermore, the complexes had the capability to displace the DNA-bound MB, as shown by the competitive studies of these complexes with methylene blue (MB), thereby suggesting the intercalation mode for the competition. Finally, the theoretical studies carried out by the docking method were performed to calculate the binding constants and recognize the binding site of the BSA and DNA by the complexes. In addition, in vitro and in silico studies showed that the compounds were degradable by bacterial and fungal biodegradation activities.

DNA binding, photo-induced DNA cleavage and cytotoxicity studies of lomefloxacin and its transition metal complexes

This work was focused on a study of the DNA binding and cleavage properties of lomefloxacin (LMF) and its ternary transition metal complexes with glycine. The nature of the binding interactions between compounds and calf thymus DNA (CT-DNA) was studied by electronic absorption spectra, fluorescence spectra and thermal denaturation experiments. The obtained results revealed that LMF and its complexes could interact with CT-DNA via partial/moderate intercalative mode. Furthermore, the DNA cleavage activities of the compounds were investigated by gel electrophoresis. Mechanistic studies of DNA cleavage suggest that singlet oxygen ((1)O2) is likely to be the cleaving agent via an oxidative pathway, except for Cu(II) complex which proceeds via both oxidative and hydrolytic pathways. Antimicrobial and antitumor activities of the compounds were also studied against some kinds of bacteria, fungi and human cell lines.

Synthesis, interaction with DNA and antiproliferative activities of two novel Cu(II) complexes with Schiff base of benzimidazole

Two novel copper(II) complexes with Schiff base of benzimidazole [Cu(L)Cl]2·CH3OH have been synthesized. HL(1) (N-(benzimidazol-2-ymethyl)-5-chlorosalicylideneimine, C15H11ClN3O) and HL(2) (N-(benzimidazol-2-ymethyl)-salicylideneimine, C15H12N3O) are ligands of complex (1) and complex (2), respectively. The complexes were characterized by elemental analysis, IR, UV-Vis, TGA and X-ray diffraction. Within the complexes, Cu(II) ions were four coordinated by two nitrogen atom of azomethine and imine, one phenolic oxygen atom from HL and one chloride atom. A distorted quadrilateral structure was formed. Complex (1) crystallized in the triclinic crystal system. Results showed that π-π stacking effect occurred due to the existence of aromatic ring from Schiff base and hydrogen bonding between methanol and adjacent atoms. The DNA binding properties of the complexes were investigated by electronic absorption spectra, fluorescence spectra and viscosity measurements. Results indicated that complexes bound to DNA via partial intercalation mode. The DNA binding constants Kb/(L mol(-1)) were 1.81×10(4) (1), 1.37×10(4) (2), 6.27×10(3) (HL(1)) and 3.14×10(3) (HL(2)) at 298 K. The title complexes could quench the emission intensities of EB-DNA system significantly. The results of agarose gel electrophoresis indicated complex (1) could cleave supercoiled DNA through the oxidative mechanism. The inhibition ratios revealed that complex (1) and HL(1) had strong antiproliferative activities against human breast cancer cells (MCF-7) lines and human colorectal cancer cells (COLO205) lines in vitro. The antiproliferative activities of complex (1) against MCF-7 lines (IC50=16.9±1.5 μmol L(-1)) and against COLO205 lines (IC50=16.5±3.4 μmol L(-1)) is much stronger than that of HL(1), which had the potential to develop anti-cancer drug.

Interaction with biomacromolecules and antiproliferative activities of Mn(II), Ni(II), Zn(II) complexes of demethylcantharate and 2,2'-bipyridine

Three new transition metal complexes [Mn2(DCA)2(bipy)2]·5H2O (1), [M2(DCA)2(bipy)2(H2O)]·10H2O(M=Ni(II)(2);Zn(II)(3)), (DCA=demethylcantharate, 7-oxabicyclo[2,2,1]heptane-2,3-dicarboxylate, C8H8O5) were synthesized and characterized by elemental analysis, molar conductance, infrared spectra and X-ray diffraction techniques. Each metal ion was six-coordinated in complexes. Complex 1 has a Mn2O2 center. Complexes 2 and 3 have asymmetric binuclear structure. Great amount of intermolecular hydrogen-bonding and π-π(*) stacking interactions were formed in these complex structures. The DNA-binding properties of complexes were investigated by electronic absorption spectra and viscosity measurements. The DNA binding constants Kb/(Lmol(-1)) were 1.71×10(4) (1), 2.62×10(4) (2) and 1.59×10(4) (3) at 298 K. The complexes could quench the intrinsic fluorescence of bovine serum albumin (BSA) strongly through static quenching. The protein binding constants Ka/(L mol(-1)) were 7.27×10(4) (1), 4.55×10(4) (2) and 7.87×10(4) L mol(-1) (3) and binding site was one. The complexes bind more tightly with DNA and BSA than with ligands. Complexes 1 and 3 had stronger inhibition ratios than Na2(DCA) against human hepatoma cells (SMMC-7721) lines and human gastric cancer cells (MGC80-3) lines in vitro. Complex 3 showed the strongest antiproliferative activity against SMMC-7721 (IC50=29.46±2.12 μmol L(-1)) and MGC80-3 (IC50=27.02±2.38 μmol L(-1)), which shows potential in anti-cancer drug development.

Synthesis, interaction with DNA and bovine serum albumin of the transition metal complexes of demethylcantharate and 2-aminobenzothiazole

Four new transition metal complexes (Habtz)(2)[M(DCA)(2)]·6H(2)O (M=Co(II) (1), Ni(II) (2), Cu(II) (3), Zn(II) (4); DCA=demethylcantharate, 7-oxabicyclo [2.2.1]heptane-2,3-dicarboxylate, C(8)H(8)O(5); Habtz=2-aminobenzothiazole acid, C(7)H(7)N(2)S) were synthesized and characterized by elemental analysis, molar conductance, infrared spectra and thermogravimetric analysis. The coordination number of complex was six. The X-ray diffraction analysis indicated that complex 3 crystallized in the triclinic crystal system with P1¯ space group. The DNA-binding properties of the complexes were investigated by electronic absorption spectra, fluorescence spectra, viscosity measurements. Title complexes could bind to DNA via partial intercalative mode. The K(b) of the complexes were 5.33×10(4) (1), 7.04×10(4) (2), 9.91×10(4) (3) and 5.03×10(4) L mol(-1) (4). The results of agarose gel electrophoresis showed that Cu(II) complex could cleave pBR322 plasmid DNA via radical-based mechanism. The complexes could quench the intrinsic fluorescence of bovine serum albumin (BSA) through a static quenching with the binding constants K(a) of 1.11×10(4) (1), 1.24×10(6) (2), 8.42×10(5) (3) and 1.75×10(4) L mol(-1) (4). The complexes had intense antiproliferative activities against human hepatoma cell lines (SMMC7721) and human gastric cancer cells (MGC80-3) lines in vitro. Cu(II) complex had the strongest activity against human gastric cancer cells.