Investigation And Separation of Nitrofurazone-DNA Derivatives Produced by Ɣ-Radiation

Abstract

<p>Gamma irradiation (¹³⁷Cs) of aqueous solutions of DNA and ¹⁴C-nitrofurazone (NF), labelled in the semi-carbazone moiety, produced DNA to which NF was covalently bound. Maximum binding occurred under hypoxic conditions. The binding was first order with respect to DNA concentration and was independent of NF providing excess drug was present. Enzymatic hydrolysis of the purified labelled DNA to the nucleotide and nucleoside stages was achieved in volatile buffers. Chromatographic separation of the various components in nucleotide and nucleoside hydrolysates was examined on Sephadex G-50, G-25, G-10, DEAE A-25, and AG 50WX4 columns. The AG 50WX4 column provided good clean preliminary separation of the NF derivatives from normal nucleosides and separation of derivatives into four groups. The Sephadex DEAE A-25 column allowed a more complete separation of NF derivatives. Single stranded DNA exhibited enhanced binding of NF over double stranded DNA. Nucleoside hydrolysates gave different proportions of the NF derivatives from irradiated single stranded or double stranded DNA. Deoxyribohomopolymers were used to assess the origin of the NF derivatives. Two major derivatives were common to all deoxyribohomopolymers suggesting ribose or phosphate derivatives. The other two groups of derivatives had UV absorption between 270 and 250 nm and appeared to be somewhat acidic in nature as assessed by their mobilities on ion exchange columns.</p>