1. Department of Biology- Razi University- Kermanshah- IRAN 2. Faculty of Chemistry, Razi University, Kermanshah, IRAN 3. Biochemistry department- Biology Faculty-Tarbiat Modares University, Tehran, IRAN 4. School Teacher
Recently, the use of pesticides in agriculture has been increased dramatically. it is argued that the exposure to pesticides may contribute to some diseases. ethylenethiourea (etu) is a metabolite of mancozeb, belongs to the subclass of dithiocarbamate fungicides that is neurotoxic to daergic and gabaergic neuronal cell populations in vitro after acute exposure. etu is excreted in urine. the genetic toxicity of etu has been proven, but the mechanism of the interaction of etu with dna has not been studied yet. the current research evaluated the interaction of etu and with dna by spectroscopic technique.
The interaction of native calf thymus dna with etu, in 10 mm hepes aqueous solutions at neutral ph=7.2, has been investigated by spectrophotometric technique.
The band at 260 nm of dna arises due to the π–π* transitions of dna bases. it is found that etu molecules interact with dna as are evidenced by hypochromism in uv absorption dna band.
Absorption spectra of dna in the absence and presence of etu indicated that etu makes neither covalent nor intercalate bonds with dna bases. since the etu does not contain any aromatic ring to facilitate the intercalating, the classical intercalative interaction is precluded. the uv/vis results may be due to the groove binding of dna with etu via hydrogen bonding of etu with the n7 and/or o6 atoms of the adjacent guanine bases. from the very beginning, it was postulated that groove binding compounds containing donor or acceptor hydrogen groups could selectively react with dna bases via hydrogen bonding. it is well known that the etu has two symmetric n-h groups and acts as donor hydrogen bonding one, whereas the guanine bases participate with their n7 and o6 atoms as hydrogen acceptor groups located at the dna structure. therefore, etu can bind to dna via hydrogen binding and change the dna conformation causing dna vulnerable to some structural damages that may lead to mutations. thus, there should be more caution in applying pesticides in agriculture and industry.