title: Binding studies of the anti-retroviral drug, efavirenz to calf thymus DNA using spectroscopic and voltammetric techniques.
abstract: Interactions between efavirenz (EFZ) with calf thymus DNA (CT-DNA) were investigated in vitro under stimulated physiological conditions using multispectroscopic techniques, cyclic voltammetry viscosity measurement, and gel electrophoresis. Methylene blue and acridine orange dyes were used as spectral probes by fluorescence spectroscopy. Hypochromicity was observed in ultra-violet (UV) absorption band of EFZ. Considerable fluorescence enhancement of EFZ was observed in the presence of increasing amounts of DNA solution and the binding constants (Kf ) and corresponding numbers of binding sites (n) were calculated at different temperatures. Thermodynamic parameters including enthalpy change (ΔH) and entropy change (ΔS) were calculated to be -304.78 kJ mol(-1) and -924.52 J mol(-1)  K(-1) according to the van 't Hoff equation, which indicated that reaction is predominantly enthalpically driven. In addition, UV/vis absorption titration of DNA bases confirmed that EFZ interacted with guanine and cytosine preferentially. Gel electrophoresis of DNA with EFZ demonstrated that EFZ also has the ability to cleave supercoiled plasmid DNA. Circular dichroism study showed stabilization of the right-handed B form of CT-DNA. All results suggest that EFZ interacts with CT-DNA via an intercalative mode of binding.
authors.affiliation: Department of Chemistry, Razi University, Kermanshah, Iran.
authors.forename: Marzieh
authors.initials: M
authors.lastname: Sadeghi
authors.affiliation: Department of Chemistry, Razi University, Kermanshah, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Bayat
authors.affiliation: Department of Chemistry, Razi University, Kermanshah, Iran.
authors.forename: Shekofeh
authors.initials: S
authors.lastname: Cheraghi
authors.affiliation: Medical Biology Research Center, Kermanshah University of Medical Science, Kermanshah, Iran.
authors.forename: Khirollah
authors.initials: K
authors.lastname: Yari
authors.affiliation: Razi Herbal, Medicines Research Center, Lorestan University of Medical Sciences, P.O. Box 68149-89468, Khorramabad, Iran.
authors.forename: Rouhollah
authors.initials: R
authors.lastname: Heydari
authors.affiliation: Department of Chemistry, Razi University, Kermanshah, Iran.
authors.forename: Sara
authors.initials: S
authors.lastname: Dehdashtian
authors.affiliation: Department of Chemistry, Razi University, Kermanshah, Iran.
authors.forename: Mojtaba
authors.initials: M
authors.lastname: Shamsipur
mesh_terms: D000480:Alkynes; D044966:Anti-Retroviral Agents / Q000737:chemistry*; D048588:Benzoxazines / Q000737:chemistry*; D001665:Binding Sites; D003521:Cyclopropanes; D004247:DNA / Q000737:chemistry*; D055664:Electrochemical Techniques; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics
chemical_list: D000480:Alkynes; D044966:Anti-Retroviral Agents; D048588:Benzoxazines; D003521:Cyclopropanes; D004247:DNA; C427203:calf thymus DNA; C098320:efavirenz
keywords: dna interaction; efavirenz; intercalation