Reaction of N-methyl-N′-nitro-N-nitroguanidine and N-methyl-N-nitroso-p-Toluenesulfonamide with DNA in vitro

Radioactivity from N-[14C]methyl-N′-nitro-N-nitrosoguanidine or N-[14C]methyl-N-nitroso-p-toluenesulfonamide is incorporated into DNA in vitro. The principal product formed is 7-methylguanine. The extent of methylation of DNA by both these agents increases with increasing OH− concentration. Methylation by N-[14C]methyl-N′-nitro-N-nitrosoguanidine is increased by the presence of a thiol while methylation by N-[14C]methyl-N-nitroso-p-toluenesulfonamide is considerably reduced. The presence of HPO42− + H2PO4− decreases methylation by both agents. The extent of labelling of DNA by N-methyl-N′-nitro-N-nitroso[14C]guanidine is much lower than the extent of labelling by the methyl-labelled radiomer.