Radical cations of benzo[a]pyrene and 6-substituted derivatives: reaction with nucleophiles and DNA

1. Oxidation of benzo[a]pyrene (BP) by I2 in the presence of AgClO4 in benzene generates the BP.+ClO4-.AgI complex. This same method was used to produce radical cations from 6-FBP, 6-ClBP, 6-BrBP and 6-CH3BP. 2. Reaction of the BP, 6-FBP, 6-ClBP and 6-BrBP radical cation perchlorates with H2O produced BP 1,6-, 3,6- and 6,12- dione, whereas 6-CH3BP.+ClO4-.AgI yielded 6-CH2OHBP. 3. When BP.+ClO4-.AgI and 6-FBP.+ClO4-.AgI were reacted with NaOAc in H2O/CH3CN (9:1), 6-OAcBP was formed, in addition to the quinones. In the case of 6-ClBP.+ClO4-.AgI, a small amount of 1-OAc-6-ClBP and 3-OAc-6-ClBP was formed in addition to the diones, whereas for 6-BrBP and 6-CH3BP the reaction products were BP diones and 6-CH2OHBP respectively. 4. These results confirm the localization of charge in the BP.+ at C-6, followed by C-1 and C-3. 5. The reaction of BP with NOBF4 in CH2Cl2 produced BP.+BF4-, radical cation free of complexation with inorganic salts. 6. Reaction of BP.+BF4- with DNA produced the depurinating adducts BP-6-C8Gua, BP-6-C8dGua and BP-6-N7Gua.