Fluorescence Spectral Study of Interaction of Water-soluble Metal Complexes of Schiff-base and DNA

Abstract

Recent years have seen growing interest in the employment of small molecules for deoxyribonucleic acid (DNA) studies. [1][2][3][4][5][6] DNA might interact with small molecules according to three possible patterns: (1) The electrostatic interaction, which extends the external wall of DNA double helix and lacks selectivity; (2) Interaction with grooves of DNA; and (3) intercalation model. Some metal complexes such as Cuphenanthroline, Fe-EDTA, Mn-porphyrin and Ru-polypyridyl, can cleave or bind DNA in the presence of co-oxidants such as peroxides. 7-11 Schiff-bases are potential anticancer drugs, so they are currently studied extensively. [12][13][14][15][16] The anticancer activity of these complexes tends to increase when they complex with metal ions. 17,18 21 Gravert and his co-workers investigated DNA binding/cleaving properties of twenty-six salen complexes of Mn(III) in the presence of terminal oxidants using DNA affinity cleaving techniques, and found DNA cleaving efficiency varying with both the structure and stereochemistry of the bridge. 23 We reported metal complexes of salen interaction of DNA and found that Co-salen showed the strongest interaction of DNA and that the interactive model between Co-salen is an intercalative one. 24 This paper reports on the fluorescence spectra characteristics of water-soluble metal complexes of Schiff-base and their interactive effects on calf thymus DNA under physiological condition. The interactive pattern between metal complexes of Schiff-base and DNA was investigated by UV spectroscopy, KI quenching and competitive binding of ethidium bromide (EB) and Mn-Schiff-base with DNA.The effects of salt concentration and pH of medium on interaction of DNA and metal complexes of Schiff-base have also been investigated. Mn-Schiff-bases as a novel fluorescence probe have potential analytical applications for the determination of traces of DNA. Experimental ReagentsWater-soluble Metal-Schiff-base complexes ( The fluorescence spectral characteristics and the interaction of several water-soluble metal complexes of Schiff-base with DNA are described. Among the complexes tested, Mn-Schiff-base bound to DNA showed a marked decrease in the fluorescence intensity with a blue shift of the excitation and emission peaks. Some hypochromism in the UV absorption spectra was also observed. KI quenching and competitive binding to DNA between Mn-Schiff-base and ethidium bromide (EB) were studied in connection with other experimental observations to show that the interactive model between Mn-Schiff-base and DNA is an intercalative one. The pH and salt effect on the fluorescence properties was also investigated. The linear relationship between F/F0 and the concentration of calf thymus DNA covers 3.0 × 10 -6 -2 × 10 -4 mol L -1 , which can be utilized for determining traces of calf thymus DNA with a detection limit of 8.0 × 10 -7 mol L -1 in base pairs.

Synthesis and characterization of glycoconjugate tin(IV) complexes: In vitro DNA binding studies, cytotoxicity, and cell death

“…where absence of CT DNA [22,30,53]. The complexes 1 and 2 exhibited emission bands at 450 nm when excited at 594 nm.…”

Synthesis and DNA Binding Studies of Mg(II) Complex of Schiff Base Derived from Vanillin and L-Tryptophan

“…[4][5][6][7] The metal ions may enhance the activities of Schiff base ligands. [8] Generally, the complexes are known to bind to DNA by a series of noncovalent interactions such as intercalation, electrostatic interaction and groove binding. [9,10] In this article, a Schiff base derived from vanillin and L-tryptophan and its Mg(II) complex have been synthesized.…”

New homodi-and heterotrinuclear metal complexes of Schiff base compartmental ligand: interaction studies of copper complexes with calf thymus DNA

“…They are versatile ligands for many transition metals and provide donor atoms suitable for coordination with metal ions. On complexation, their biologi-cal activity including anticancer is considerably enhanced which has led to metal-based pharmaceuticals [6]. Additionally, compartmental ligands containing two adjacent but dissimilar coordination sites are of particular interest as for the recent recognition of the asymmetric nature of a number of dimetallic biosites [7].…”