"In-vitro studies on hydroxamic acid- CT DNA binding"
Binding studies of small molecules to DNA are very important to the development of DNA molecular probes and new therapeutic reagents. In the present investigation, the interaction between five different derivatives of hydroxamic acids, N-phenyl 2,4dichloro phenoxybutyro,
N-m-tolyl 2,4 dichlorophenoxyglutero, N-m-tolyl-4-chlorophenoxyaceto, N-m-chloro-phenyl-tertiarybutylbenzo and N-p-tolyl-iso-valero hydroxamic acids and calf thymus DNA was investigated under simulated physiological condition ( Tris-HCl buffer of pH 7.4) using ethidium bromide (EB) dye as a probe by UV-visible absorption, fluorescence spectroscopy, gel electrophoresis and hydrodynamic measurements. The absorption spectrum of the hydroxamic acids showed that as the concentration of DNA increases, a large degree of hypochromism develops in the spectrum. Fluorescence quenching emission peak was seen in the DNA-EB system when compound was added. The Stern-Volmer constant was calculated and obtained as 2.7 x 105 M-1, 1.5 x 103 M-1, 9.9 x 104 M-1, 4.5 x 103 M-1 and 1.6 x 105 M-1 for all the five hydroxamic acids respectively. The competitive binding studies showed that the complexes can displace the DNA bound EB, suggesting strong competition with EB. The DNA cleavage activity of the hydroxamic acid- DNA complexes were ascertained by gel electrophoresis assay which revealed that the complexes possess good DNA cleavage activity. Viscometric studies complimented the UV results where a continuous increase in relative viscosity of the DNA solution was observed with added optimal hydroxamic acid concentration. All the experimental evidences indicate that these compounds can strongly bind to CT-DNA through an intercalative mode.
N-m-tolyl 2,4 dichlorophenoxyglutero, N-m-tolyl-4-chlorophenoxyaceto, N-m-chloro-phenyl-tertiarybutylbenzo and N-p-tolyl-iso-valero hydroxamic acids and calf thymus DNA was investigated under simulated physiological condition ( Tris-HCl buffer of pH 7.4) using ethidium bromide (EB) dye as a probe by UV-visible absorption, fluorescence spectroscopy, gel electrophoresis and hydrodynamic measurements. The absorption spectrum of the hydroxamic acids showed that as the concentration of DNA increases, a large degree of hypochromism develops in the spectrum. Fluorescence quenching emission peak was seen in the DNA-EB system when compound was added. The Stern-Volmer constant was calculated and obtained as 2.7 x 105 M-1, 1.5 x 103 M-1, 9.9 x 104 M-1, 4.5 x 103 M-1 and 1.6 x 105 M-1 for all the five hydroxamic acids respectively. The competitive binding studies showed that the complexes can displace the DNA bound EB, suggesting strong competition with EB. The DNA cleavage activity of the hydroxamic acid- DNA complexes were ascertained by gel electrophoresis assay which revealed that the complexes possess good DNA cleavage activity. Viscometric studies complimented the UV results where a continuous increase in relative viscosity of the DNA solution was observed with added optimal hydroxamic acid concentration. All the experimental evidences indicate that these compounds can strongly bind to CT-DNA through an intercalative mode.
