Alkylating activities of various alkylating agents were examined by using nicotinamide. One μmol of alkylating agent was incubated with nicotinamide (25-200 μmol) in a phosphate buffer (pH 7.4) at 37°C for 24 h. The resulting N1-alkylnicotinamide was converted to 2-alkyl-6-phenyl-2, 8-dihydro-8-oxo-2, 7-naphthyridine and analyzed by high-performance liquid chromatography with a fluorescent detector. Alkylating activity was expressed as percentage of the formed N1-alkylnicotinamide against 1 μmol of the standard N1-alkylnicotinamide. In methylation and ethylation, the alkylating activity was in the order of methyl methanesulfonate (100%), dimethyl sulfate (68%), methyl iodide (21%) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) (20%), and ethyl methanesulfonate (93%), diethyl sulfate (68%), ethyl iodide (3%) on addition of 200 μmol nicotinamide. MNNG known as mutagen and carcinogen, have not so high activity. Propylene oxide and 1, 2-butylene oxide show 100% alkylating activities under the same reaction conditions as described above on addition of 200 μmol nicotinamide.
