Structural requirements for the mutagenicity of environmental nitroarenes.

The nitroarenes comprise a large group of widely distributed environmental agents some of which are extraordinarily mutagenic while others are devoid of such activity. A newly developed computer program has been used to determine which structural features of these molecules might account for this broad spectrum of activities. Using Salmonella mutagenicity data for 53 nitroarenes , 2 fragments associated with activity and 2 deactivating fragments have been identified. The coexistence of an active and a deactivating fragment on the same molecule results in a nitroarene possessing marginal or no mutagenicity. The activity of 47 of 53 nitroarenes was correctly predicted by this procedure. Most of the discrepancies involved hexa- and heptacyclic nitroarenes which were predicted to be active but reported to be inactive. The 'CASE' program can be used to predict the mutagenicity of the many untested nitroarenes identified in the ambient environment.