Formation of the Cross-Linked Base, Diguanylethane, in DNA Treated with N,N′-Bis(2-chloroethyl)-N-nitrosourea¹

A cross-linked base, diguanylethane, has been isolated and identified as a product of the reaction of N,N′-bis(2-chloroethyl)-N-nitrosourea with DNA. DNA was reacted at 37° with N, N′-bis(2-chloroethyl)-N-nitosourea in neutral aqueous solution, isolated by precipitation with ethanol, washed, and heated briefly at 100° to release a purine fraction. This fraction was separated by high-pressure liquid chromatography and found to contain both chloroethylguanine and 1,2-diguanylethane. Formation of the latter product may be related to the cytotoxicity of N,N′-bis(2-chloroethyl)-N-nitrosourea.