In vitro reaction of N-n-butyl-N-nitrosourea and n-butyl methanesulphonate with guanine and thymine bases of DNA

The reaction of N-n-butyl-N-nitrosourea (BNU) and n-butyl methanesulphonate(BMS) with DNA has been investigated. In addition to the expectedn-butylpurines formed on reaction with BNU some rearranged sec-butyl-adductswere also observed, indicating that a carbonium ion is involvedin the alkylation process by nitrosoureas. Only n-butyl adductswere observed following reaction with BMS. The reaction of thesealkylating agents with the thymine residues in the DNA was alsodetermined. The relative amounts of the various adducts formedby the two butylating agents are similar to those formed bythe corresponding ethyl and propyl compounds.