DNA binding, nuclease activity and cytotoxicity studies of Cu(ii) complexes of tridentate ligands

Abstract

Cu(II) complexes of three tridentate ligands, L(1), L(2) and L(3), [L(1), N-((1H-imidazole-2-yl)methyl)-2-(pyridine-2-yl)ethanamine; L(2), N-((1-methyl-1H-imidazole-2-yl)methyl)-2-(pyridine-2-yl)ethanamine; L(3), 2-(pyridine-2-yl)-N-((pyridine-2-yl)methyl)ethanamine] respectively, were synthesized and characterized. The single crystal X-ray structure of complex 1 reveals the pseudo octahedral coordination geometry around the copper center. Absorption and fluorescence experimental evidence show good DNA binding propensity (in the order of 10(5) M(-1)) of the complexes. Thermal denaturation and circular dichroism (CD) analyses reveal minor structural changes of calf thymus (CT) DNA in presence of complexes and groove and/or surface binding of the complexes to CT-DNA. Kinetic DNA cleavage assay shows pseudo-first-order kinetic reaction between the complex and supercoiled (SC) DNA. In addition, mechanistic SC DNA cleavage results show higher DNA cleavage activity in presence of reducing agent, due to the presence of hydroxyl radicals. In vitro cytotoxicity assay of the complexes demonstrate that the complexes have low toxicity for different cancer cell lines and IC(50) values were between 37 and 156 μM.

New vanadium complexes with 6,6″-dimethyl-2,2′:6′,2″-terpyridine in terms of structure and biological properties

“…The presence of hypo-and batochromism indicate the intercalative binding mode of tested compounds. Slight red shift in absorption spectra results from strong p-p ⁄ stacking interaction between DNA base pairs and planar aromatic ligand of investigated metal complex [61,62]. One may assume the extent of hypochromic change in absorption spectra is consistent with the strength of interaction.…”

Synthesis and the characterization of Schiff-base copper complexes: Reactivity with DNA, 4-NPP and BNPP

“…It is noteworthy to mention that the K b values obtained for complex 1 and complex 2 are about ten times greater than the value reported for the DNA intercalator complex [Ru(phen) 2 (-dpq)] 2+ . A K b value of 1.41 Â 10 5 M À1 has been reported for some copper complexes [76]. …”

Synthesis and multi-spectroscopic DNA binding study of 1,3,4-oxadiazole and 1,3,4-thiadiazole derivatives of fatty acid

“…As reported earlier that enhanced fluorescence of EB-CT-DNA system can be quenched by the addition of second molecule [12,15]. So in order to confirm the mode of binding of 3a and 6a with the CT-DNA, we have used EB as a probe.…”

“…Generally, hypochromism and red shift are associated with the intercalative binding mode between molecules and DNA [11] whereas hyperchromism is correlated with groove binding between host and guest [12]. Since the compounds 3a and 6a showed the band in the UV-range under identical experimental conditions, here we just discuss the apparent changing of UV bands of 3a and 6a when interacted with CT-DNA.…”