The metabolic activation of dibenzo[a,e]fluoranthene in vitro. Evidence that its bay-region and pseudo-bay-region diol-epoxides react preferentially with guanosine.

Dibenzo[a,e]fluoranthene ( DBF ), a non- alternant carcinogenic polycyclic aromatic hydrocarbon (PAH), binds covalently to DNA. The main adducts were characterized as covalent additions of its bay-region and pseudo-bay-region diol-epoxides. The structure of these 2 adducts was analyzed by mass spectrometry using their persilyl derivatives. 3,4-Dihydroxy-1,2-epoxy-1,2,3,4-tetrahydro- DBF (3,4-diol-1,2-epoxy- DBF ) and 12,13-dihydroxy-10,11-epoxy-10,11,12,13-tetrahydro- DBF (12, 13-diol-10,11-epoxy- DBF ) obtained by synthesis were allowed to react in vitro with calf thymus DNA or with poly(G). The comigration of DNA and poly(G) adducts isolated after acid hydrolysis of DNA and poly(G) was in good agreement with mass spectroscopic results: both bay-region and pseudo-bay-region DBF diol-epoxides reacted with guanine residues.