Fluorescence Interaction and Determination of Calf Thymus DNA with Two Ethidium Derivatives

Abstract

In this paper, we reported the syntheses and investigation of the modes of binding to DNA of the two new ethidium derivatives containing benzoyl and phenylacetyl groups of both amines at 3-and 8- positions. The interactions between calf thymus DNA (ct-DNA) and the two derivatives, 3,8-dibenzoylamino-5-ethyl-6-phenylphenantridinium cloride (E2) and 3,8-diphenylacetylamino-5-ethyl-6-phenylphenantridinium chloride (E3), were investigated by fluorescence quenching spectra and UV-vis absorption spectra. The Stern-Volmer quenching constants, binding constants, binding sites and the corresponding thermodynamic parameters DeltaH, DeltaS and DeltaG were calculated at different temperatures. The results indicated the formation of E2 and E3-DNA complexes and van der Waals interactions as the predominant intermolecular forces in stabilizing for each complex. In addition, increasing nucleophilicity of the functional groups at 3- and 8- positions exhibited the respectable increment the DNA binding affinities of derivatives. The results of absorption, ionic strength and iodide ion quenching suggested that the interaction mode of E2 and E3 with ct-DNA was intercalative binding. The limit of detection (LOD) of ct-DNA were 7.49 x 10(-8) (n = 4) and 4.18 x 10(-8) mol/l (n = 7) in presence of E2 and E3, respectively.

Novel 3-Aminothiazolquinolones: Design, Synthesis, Bioactive Evaluation, SARs, and Preliminary Antibacterial Mechanism

“…The intercalative and groove binding modes are more effective to block DNA replication than that of electrostatic interaction. 44 It has been revealed that when using an anionic quencher, the DNA base pairs around the intercalators hinder the accessibility of the fluorescent probe to the quencher. However, the use of electrostatic repulsion between the anionic quenchers and DNA phosphate backbones can be beneficial for the intercalated species.…”

“…It is generally accepted that small molecules have three binding modes with DNA by noncovalent interactions, including intercalation with base pairs, groove binding, and electrostatic interaction with the anionic sugar phosphate backbone. The intercalative and groove binding modes are more effective to block DNA replication than that of electrostatic interaction …”

An Overview of Analytical Techniques Employed to Evidence Drug-DNA Interactions. Applications to the Design of Genosensors

“…The quenching effect shows a good adjustment to the Stern-Volmer equation with K SV constants of 8.4 x 10 6 and 4.6 x 10 6 . Studies concerning temperature on the quenching effect showed that K SV decreased when temperature was increased and the authors suggest a static mechanism for the quenching (Akbay et al, 2009). Other studies concerning the interaction of ethidium bromide analogues with DNA have shown that the presence of weak electron-donating substituents on phenantridinium moiety favours a significant fluorescence quenching (Prunkl et al, 2010).…”

The influence of GC/AT composition on intercalating and semi-intercalating binding of ethidium bromide to DNA

“…EtBr and EtBr-polynucleotide complexes fluorescence was recorded at 610 nm (excitation at 540 nm). 12,15,16 The adsorption isotherms in Schatchard's coordinates were obtained as described in the literature.…”