7H-Dibenzo[c,g]carbazole (DBC) is a potent liver, lung and skin carcinogen
while dibenz[a,j]acridine (DBA) is a moderate skin carcinogen. DEC is metab
olized to phenols and DBC-DNA adducts are formed through the 2-, 3-, and 4-
phenols or directly through radical cations. Mutations in ras as a result o
f DEC, activation are found exclusively in codon 61 in liver, lung and skin
. DBA is metabolized to dihydrodiols, and phenols and DBA-DNA adducts are f
ormed through the diol-epoxides and possibly through bis-diol-epoxides. Mut
ations in ras, as a result of DBA activation, are found in codons 12, 13, a
nd 61. These results indicate that although the two compounds are structura
lly similar, differing by one carbon in the middle ring, there are differen
ces in their metabolism, DNA binding, mutational spectra and target-organ c
arcinogenesis.