Nucleotides bearing a cleavable genotoxic group on the phosphate

A new class of nucleotide derivatives in which N-nitroso-pyrrolidine (NPYR) is linked to the phosphate group through an ester linkage at the alpha-carbon of the nitrosamine were prepared by a reaction between a nucleoside monophosphate and alpha-acetoxy-NPYR. The NPYR derivatives were prepared from dpT, dpC, dpA, dpG, pA and dpCpT. Treatment of the NPYR-pX with acid, snake venom phosphodiesterase, or near ultraviolet light caused cleavage of the NPYR group, regenerating pX. All of these nucleotide derivatives were directly mutagenic towards Salmonella typhimurium TA1535. When phage M13mp2 double-stranded covalently closed circular DNA was treated with NPYR-dpT with near ultraviolet irradiation, single strand breaks of the DNA took place.