Several methylated analogs of
fluorene were evaluated as
mutagens in Salmonella typhimurium TA98 and TA100 in the presence and absence of microsomal activation. Among the methylated derivatives of
fluorene assayed were
9-methylfluorene, 2-fluoro- and 2,7-difluoro-9-methylfluorene, 1,9-, 2,9-, 3,9- and 4,9-dimethylfluorene, 2,3,9-trimethylfluorene and 2,7,9-trimethylfluorene. Mutagenic activity was observed for several of these
fluorene derivatives in the presence of rat liver homogenate. The data support a previous observation that a single methyl substituent in the 9-position of
fluorene is associated with mutagenic activity within this series of compounds. Substitution with
fluorine at both the 2- and 7-positions of
9-methylfluorene was not associated with a loss of mutagenic activity as evidenced by the similar mutagenic activity of 2,7-difluoro-9-methylfluorene and
9-methylfluorene. However, 2,7,9-trimethylfluorene was not mutagenic under these assay conditions.
9-Methylfluorene, 1,9-, 2,9-, 3,9- and 4,9-dimethylfluorene and 2,3,9-trimethylfluorene were active as
mutagens in the presence of rat liver homogenate, but were inactive as
tumor initiators when assayed on mouse skin.