P. Hrelia et al., Influence of nitroreductase and O-acetyltransferase on the mutagenicity ofsubstituted nitrobenzothiophenamines in Salmonella typhimurium, CHEM-BIO IN, 118(2), 1999, pp. 99-111
The mutagenic activity of 17 substituted (aryl)(2-nitrobenzo[b]thiophen-3yl
)amine has been evaluated in the Ames test with different isogenic strains
of Salmonella typhimurium, that varied in their expression of nitroreductas
e and O-acetyltransferase. Active derivatives induced frameshift mutations
in TA98 strain, and differences in the chemical structure resulted in up to
15-fold changes in mutagenic activity. The non-mutagenic compounds are the
unsubstituted parent compound and derivatives with pam-chloro, para-fluoro
, para-diethylamino, meta-bromo and para-dimethylamino groups. They do not
show any activity even in strains with higher level of nitroreductase or O-
acetyltransferase. The addition of S9 fraction decreases the mutagenic pote
ntial or gives comparable results to those obtained without metabolic activ
ation. For electron-donating substituents, the meta-isomers display the gre
atest mutagenic potency, whereas the transfer of the group to the para-posi
tion leads to less active or unactive molecules. All active nitrobenzothiop
henes are substrates for bacterial nitroreductase and O-acetyltransferase,
as shown by the reduced mutagenicity in the deficient strains and increased
mutagenicity in the corresponding overproducing bacteria. Previous reports
have pointed out interest in nitrothiophene analogues with para-chloro, an
d para-fluoro substituents as promising anti-inflammatory drugs. The presen
t study further enhances the putative interest in these derivatives, based
on absence of mutagenicity. (C) 1999 Elsevier Science Ireland Ltd. All righ
ts reserved.