Synthesis, characterization and antitumor activity of Ln(III) complexes with hydrazone Schiff base derived from 2-acetylpyridine and isonicotinohydrazone.

In the present study, two isostructural lanthanide (Ln)(III) complexes, namely Ln(HL)2(NO3)(CH3OH)2)·CH3OH, where Ln = La in complex 1 and Ce in complex 2, and hydrogen ligand (HL) = (E)-N'-[1-(2-pyridinyl)ethylidene]isonicotinohydrazone, have been isolated and characterized by elemental analysis, infrared spectra and single-crystal X-ray diffraction analysis. The results revealed that the acylhydrazone ligand HL in each complex was deprotonated as an anionic ligand and coordinated to the central La(III) ion via enolization of oxygen and nitrogen atoms. Furthermore, the antitumor effects and potential mechanisms of the two complexes were explored in the human lung cancer cell line A549 and in the human gastric cancer cell lines BGC823 and SGC7901. In the present study, the roles the two complexes on the proliferation and apoptosis of the above tumor cell lines were determined by MTT assay and Annexin V/propidium iodide flow cytometry, respectively. Furthermore, various apoptosis-associated key genes, including caspase 3, B cell lymphoma (Bcl)-2-associated X protein (Bax) and Bcl-2, were detected by western blotting to explore the possible antitumor mechanisms of the two complexes. The results revealed that the two complexes had comparable antitumor activities in terms of inhibiting proliferation and inducing apoptosis in tumor cell lines. The changes in the protein expression levels of caspase 3, Bax and Bcl-2 further verified the apoptosis-promoting mechanisms of the two complexes in tumor cell lines. These findings have a great potential in biomedical applications of novel Ln(III) complexes.

Synthesis, characterization, and antitumor activity of three ternary dinuclear copper (II) complexes with a reduced Schiff base ligand and diimine coligands in vitro and in vivo.

Three ternary copper (II) complexes containing 1,10-phenanthroline (phen, 1), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq, 2) and dipyrido[3,2-a:2',3'-c]phenazine (dppz, 3), with the formulation [Cu2(NCL)2(H4PASP)]·4.5H2O (1-3) (where NCL=the diimine coligand, H4PASP=N,N'-(p-xylylene)di-2-aminosuccinic acid), were isolated and characterized. The binding of these complexes with calf thymus DNA was studied using UV-visible absorption titration, emission, and circular dichroism spectroscopy, among other methods. The changes in physicochemical properties that occurred upon binding of these complexes with DNA indicate that binding occurs primarily through intercalative interactions. Human tumor cell lines HeLa, PC3, and HepG2 were treated with the copper(II) complexes in vitro and cell survival rate was assessed by 3-(4,5-dimethyl thiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) assay and crystal violet survival assay. Flow cytometry was performed on treated cells labeled with AnnexinV/Propidium Iodide staining to determine rates of apoptosis. Western blot was performed to determine the expression levels of the apoptotic markers p53, Bax, and Bcl-2. The complexes reduced cell viability and induced apoptosis in cells of human tumor cell lines in a dose-dependent manner. In addition, using a nude mouse xenograft model, we found that the three ternary copper (II) complexes inhibited human tumor cell growth in vivo. In conclusion, these novel synthetic copper complexes have profound antitumor effects on human tumor cells and are promising therapeutic agents for human tumors.

Ternary Dinuclear Copper(II) Complexes of a Reduced Schiff Base Ligand with Diimine Coligands: DNA Binding, Cytotoxic Cell Apoptosis, and Apoptotic Mechanism.

A serial of mixed-ligand Cu(II) complexes of the type [Cu(phens)(H2 PDILeu)]H2 O (1-4) containing phens as 2,2'-bipyridyl (bpy, 1), 1,10-phenanthroline (phen, 2), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq, 3), and dipyrido[3,2-a:2',3'-c]phenazine (dppz, 4) have been isolated and characterized. The interaction of the complexes with calf-thymus DNA has been explored by physical methods to propose modes of DNA binding of the complexes, which indicate that 4 interacts with DNA more strongly than all of the other complexes through intercalation interaction. Furthermore, cell apoptosis was detected by AnnexinV/PI flow cytometry and TUNEL assay and by Western blotting to detect the protein expression of p53, Bax, and Bcl-2. All the three copper complexes can effectively induce apoptosis of the three human tumor cells, which was accompanied with upregulation of the expression of p53 and Bax, while Bcl-2 decreased.