Promutagens, mutagenic activities

Figure 3. Mutagenic activities of the promutagens cis- and Xrms-diallate and sulfallate, the proximate mutagen cis-diallate sulfoxide, and the ultimate mutagen 2-chloroacrolein, assayed with S. typhimurium strain TA 100 sensitive to base-pair substitution mutagens. The diallate isomers and sulfallate are not mutagenic without the S9 mix. S9 mix refers to a microsomal oxidase system prepared from rat liver and appropriate cofactors. The methodology is detailed in Refs. 6, 22, and 29.

N,N-Dialkylthlo- and dithiocarbamate herbicides include several -alkyl and -benzyl compounds without mutagenic activity and three -chloroallyl derivatives which are promutagens,... 

In one of the first studies of the vapor-phase mutagenicity of polluted urban air, Alfheim and co-workers (1985) collected both ambient particles and vapor-phase compounds and used the Salmonella typhlmurium reversion assay. The direct activities ( —S9) of the extracts generally exceeded the promutagenicities (+ S9), and furthermore, the vapor-phase mutagenicity ranged from 0 to 88% of the total activity. 

In addition to species, strain, and individual genetic differences in the metabolism of mutagens and promutagens, one must consider differences related to experimental techniques. Some enzyme activities in the intact cell differ from those in isolated subcellular fractions. 

In addition to plant activation of promutagens, such as dimethyInitrosamine,16 that are also activated in mammalian metabolism, the possibility of unique abilities of plants to activate some substances warrants attention. For example, interest in metabolism of promutagens by plants was stimulated by the evidence11 0 354 that maize can activate the nonmutagenic herbicide atrazine and some related compounds to substances that cure detectable as mutagens in microbial tests. Atrazine was also mutagenic in the waxy locus test in the maize plants themselves.354... 

S-9 A metabolic activation mixture that is used with many in vitro genetic-toxicity tests to provide for the conversion of promutagens into mutagens the enzymatic activities of an S-9 mixture are those of a post-mitochondrial supernatant (i.e., microsomal and cytosolic enzymes) derived from a mammalian liver homogenate the expression "S-9" originally referred to supernatant from centrifugation at 9,000 rpm. 

The promutagen 2-aminofluorene (29) was activated to an unknown mutagenic compound by exposure to sunlight oxygen was required for activity. Mixtures of oxidized nitrogen species were suggested to be the active agents (White and Heflich,... 

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