Synthesis, Characterization, Antioxidant Activities, and DNA-Binding Studies of (<i>E</i>)-<i>N</i>&prime;-[1-(Pyridin-2-yl)ethylidene]isonicotinohydrazide and Its Pr(III) and Nd(III) Complexes

Abstract

It is well-known that Schiff bases play important role in bioinorganic chemistry and their metal complexes have been studied extensively for decades. These interesting ligand systems contain different donor sites in heterocyclic rings, e.g., NNO or NNS, which give rise to the architectural beauty of these coordination complexes.1) Among the ligand systems, hydrazide and hydrazone occupy important places because transition metal complexes of these ligands have been developed due to their chelating capability, structural flexibility, interesting electrical as well as magnetic properties, and various pharmacological activities, such as antibacterial, antitumoral, antiviral, antimalarial, and antituberculosis actions. 2,3)Investigation of molecular complexes of lanthanide ions has attracted significant attention, owing to their broad ranging fluorescent applications in biochemistry, material chemistry, medicine and so forth. [4][5][6] However, there have been only a few DNA-binding investigations of such complexes have been relatively few. Because the interaction between metal complexes and DNA is closely related to their potential biological and pharmaceutical activities, studies on the DNAbinding of metal complexes are very important in the development of new therapeutic reagents and DNA molecular probes. 7,8) Various coordination compounds of aroylhydrazones have been reported to act as enzyme inhibitors and are useful due to their pharmacological applications. 9,10)Here, we synthesized (E)-NЈ-[1-(2-pyridinyl)ethylidene]-isonicotinohydrazide (HL) and prepared its two of its lanthanide(III) complexes (Chart 1). The DNA-binding properties and antioxidant activities of the two lanthanide(III) complexes with HL are reported herein. ExperimentalMaterials Nitroblue tetrazolium (NBT), methionine (MET), vitamin B 2 (VitB 2 ), calf thymus DNA (CT-DNA) and ethidium bromide (EB) were obtained from Sigma Chemical Co. All experiments involving interaction of the complexes with CT-DNA were carried out in doubly distilled water buffer containing 5 mM Tris [Tris(hydroxymethyl)-aminomethane] and 50 mM NaCl, and adjusted to pH 7.2 with hydrochloric acid. The DNA concentrations of the solutions were determined from their UV absorption at 260 nm using the molar absorption coefficient e 260 ϭ6600 mol Ϫ1 cm Ϫ1. DNA Purity was checked by monitoring the ratio of the absorbance at 260 nm to that at 280 nm. The solution gave a ratio of A 260 /A 280 Ͼ1.80, indicating that DNA was sufficiently free from protein. 11)Physical Measurements The UV-vis absorption measurements were conducted by using a Varian Cary 100 spectrophotometer equipped with quartz cells. All fluorescence emission spectra were measured using a Hitachi F-4500 spectrofluorophotometer equipped with a xenon lamp source and a quartz cell of 5 cm path length. Viscosity experiments were carried out on an Ubbelodhe viscometer. The circular dichroic (CD) spectra were recorded on a Jasco J-810 spectropolarimeter. The 1 H-NMR spectra were recorded with a Bruker ACF300 FT-NMR instrum...

Synthesis, characterization and anticancer activities of transition metal complexes with a nicotinohydrazone ligand

“…The vibrations ν(N-H) disappeared in the spectra of the four complexes, indicating that the ligand was deprotonated. The novel bands near 560 cm -1 for the complexes were assigned to ν(M-O), and the weaker peaks near 470 cm -1 were assigned to ν(M-N), respectively (23,24), consistent with the results of X-ray diffraction analysis.…”

“…It has been reported that arylhydrazone and its metal complexes exhibit markedly effective antitumor activities, possibly due to their NO bidentate systems (24). In vitro cytotoxicity assays were carried out in the human A549 (human lung cancer), BGC823 (human gastric cancer) and Eca109 (human esophageal cancer) solid tumor cell lines.…”

Synthesis, characterization and anticancer activities of two lanthanide(III) complexes with a nicotinohydrazone ligand

“…The ligand penh was synthesized according to the literature method while nicotinoyl hydrazide instead of isonicotinoyl hydrazide [19] . Yield, 93.1%.…”

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

“…The ligand HL was prepared as described previously (20). In brief, HL was obtained by condensation of 2-acetylpyridine (0.1 mmol) and isonicotinohydrazone (0.1 mmol) in ethanol solution with the addition of 0.1 ml concentrated acetic acid.…”