The reaction of (+/-)-7alpha, 8beta-dihydroxy-9beta, 10beta-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene with DNA

The reaction of (+/-)-7alpha,8beta-dihydroxy-9beta,10beta-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene (BP diol epoxide) with DNA, followed by enzymatic hydrolysis and LH 20 Sephadex column chromatography, yielded products containing a purine deoxyribonucleoside linked to a 7,8,9,10-tetrahydrobenzo(a)pyrene derivative. DNA containing tritiated adenine or pyrimidines gave little or no tritiated products, showing that reaction occurred chiefly with the guanine residues. Results with 8-(3H)-guanine-labelled DNA, and studies on the protonation and ionization of the products in acid or alkaline media, led to the formulation of the main product as an N2-substituted guanine derivative. The reaction of BP diol epoxide with deoxyadenosine and deoxyguanosine gave further nucleoside derivatives which were probably minor products in the reaction with DNA. Treatment with strong acid unexpectedly converted each of the isolated products to free guanine or adenine.