Mutagenicity of bay-region amino-substituted cyclopenta[a]phenanthrenes and 2-and 5-aminochrysene

The relative mutagenic potentials of 11-amino-16, 17-dihydro-15H-cyclopenta [a]phenanthrene, its 17-keto derivative, and 2-and 5-aminochrysene have bee n compared in Salmonella typhimurium TA98 and TA100 in the presence of a po stmitochondrial liver preparation from Aroclor 1254 induced rats. The 11-am ino hydrocarbon is a very weak mutagen (0.27 revertants/nmol), whereas the 11-amino-17-ketone is much more active (129 revertants/nmol). 2-Aminochryse ne is the most mutagenic arylamine (similar to 500 revertants/nmol) among t hese compounds, but its 5-amino isomer is much less active (0.9 revertants/ nmol). Possible reasons for these marked differences are suggested. Use of TA98 with over-expressing O-acetyltransferase (YG 1024) and deficien t in this enzyme (TA98/1,8-DNP6) with the 11-amino-17-ketone and with 5-ami nochrysene clearly indicates the importance of this enzyme in their bioacti vation, implying oxidation of the amino group to the hydroxylamine in both these compounds. (C) 2001 Elsevier Science B.V. All rights reserved.