Alkylation of guanosine and 2′-deoxyguanosine by o-quinone α-(p-anisyl)methide in aqueous solution

Abstract

Rates of alkylation of guanosine and 2′-deoxyguanosine with o-quinone α-(p-anisyl)methide were measured by flash photolysis in a series of aqueous sodium hydroxide solutions and bicarbonate ion, t-butylhydrogenphosphonate ion, and biphosphate ion buffers. The data so obtained provide rate profiles for these nucleoside plus quinone methide reactions over the range pH = 7–14, which furnish guanosine and deoxyguanosine acidity constants consistent with literature information. These profiles also provide rate constants that show the reaction of o-quinone α-(p-anisyl)methide with guanosine and deoxyguanosine to be fairly fast processes, considerably faster than the biologically wasteful reaction of the quinone methide with water, which is the ubiquitous medium in biological systems; that makes the quinone methide a potent guonosine and deoxyguanosine alkylator.