3H-labelled alkyl-nucleotides, -nucleosides and -bases for the immunoanalytical quantification of DNA damage and repair

Analysis of the formation and repair of structurally modified DNA is of particular interest in the study of carcinogenesis, cancer therapy and aging. The quantification of specific DNA lesions by sensitive immunoanalytical methods requires radiotracers with high specific activity. We describe the synthesis of 3H‐labelled adenine‐, cytosine‐, guanine‐ and thymine‐alkyl derivatives by nucleophilic N‐ and O‐alkylation using alkyl halides and diazoalkanes: 3‐alkyl‐[8‐3H]adenine (Alkyl = Me, Et, n‐Bu); O6‐alkyl‐deoxy[1′,2′‐3H]guanosine (Alkyl = Me, Et, i‐Pro, n‐Bu); O6‐ethyl‐deoxyguanosine‐5′‐triphosphate ([2‐3H‐Ethyl]; [8‐3H]); O6‐alkyl‐9‐hydroxyhexyl‐[8‐3H] guanine (Alkyl=Me, Et); 7‐ethyl‐[8,5′‐3H]guanosine‐3′,5′‐cyclic‐phosphate; O2‐andO4‐alkyl‐[methyl, 1′,2′‐3H]thymidine (Alkyl=Me, Et); the conversion of 3H‐labelled thymidine to the corresponding 5‐methylcytidine; the synthesis of three different 8‐oxo‐guanine tracers; and the generation of thymidine glycol (5,6‐dihydroxy‐5,6‐dihydro‐[methyl‐3H]thymidine) from thymidine. All radiotracers were sucessfully employed in competitive radioimmunoassays for the quantification of defined DNA alkylation products in DNA repair analyses. Copyright © 2003 John Wiley & Sons, Ltd.