DNA interaction studies of ethylenediaminetetraaceticacid food additive and selenium effect in DNA cleavage-inhibition

The interaction of native calf thymus DNA with ethylenediaminetetraaceticacid (EDTA) in Tris-HCl buffer at pH?=?7.8 (at this pH EDTA forms a disodium salt) was investigated. EDTA is widely used in medicine, food technology, and the chemical industry. The DNA binding mode of EDTA was monitored by absorption spectrophotometry, circular dichrosim, viscometry, and gel electrophoresis. Ultraviolet spectra of DNA showed small hyperchromicity with increase in EDTA concentration. The circular dichrosim signals at 245 and 280?nm indicated structural changes in DNA structure, and no significant effect on DNA viscosity was observed in the presence of increasing amounts of EDTA. Results are indicative of an outside, nonintercalative binding mode of EDTA to DNA. Moreover, gel electrophoresis studies showed considerable oxidative cleavage of plasmid DNA by EDTA. Mechanistic aspects of the chemical nuclease reactions were investigated using the OH radical quencher dimethylsulfoxide. In the presence of selenium, DNA cleavage by EDTA was inhibited.