title: Mutagenic and cytotoxic activity of benzol[a]pyrene 4,5-, 7,8-, and 9,10-oxides and the six corresponding phenols.
abstract: The benzo[a]pyrene 4,5-, 7,8-, and 9,10-oxides and the six corresponding phenols (4-, 5-, 7-, 8-, 9-, and 10-hydroxybenzo[a]pyrene) have been tested for mutagenic and cytotoxic activity in bacteria and in a mammalian cell culture system. Benzo[a]pyrene 4,5-oxide (K-region) was highly mutagenic in two histidine-dependent strains (TA1537 and TA1538) of Salmonella typhimurium which detect frameshift mutagens. In contrast, benzo[a]pyrene 7,8- and 9,10-oxides were less than 1% as mutagenic as the 4,5-oxide. Benzo[a]pyrene 7,8- and 9,10-oxides were unstable in aqueous media, whereas the 4,5-oxide was stable for several hours. This difference in stability could not account for the different mutagenic activities of the three arene oxides. The benzo[a]pyrene oxides were inactive in a strain (TA1535) that is reverted by base pair mutagens such as N-methyl-N'-nitro-N-nitrosoguanidine or in a strain (TA1536) that detects framshift mutagens similar to the acridine half-mustard ICR-191. Benzo-[a]-pyrene and the six phenols were all stable in aqueous media, but they had little or no mutagenic activity in any of the four Salmonella strains. Conversion of 8-azaguanine-sensitive Chinese hamster V79 cells to 8-azaguanine-resistant variants was increased by benzo[a]pyrene 4,5-oxide, whereas the 9,10-oxide was considerably less active. Benzo[a]pyrene and the other derivatives had little or no effect. Benzo[a]yrene 4,5-oxide was more cytotoxic to the Chinese hamster V79 cells than the 7,8- and 9,10-oxides, while 8-hydroxybenzo[a]pyrene was the most cytotoxic of the six phenols.
mesh_terms: D001580:Benzopyrenes / Q000494:pharmacology*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D006639:Histidine / Q000378:metabolism; D009153:Mutagens; D010087:Oxides / Q000494:pharmacology; D010636:Phenols / Q000494:pharmacology; D012486:Salmonella typhimurium / Q000187:drug effects / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D001580:Benzopyrenes; D009153:Mutagens; D010087:Oxides; D010636:Phenols; D006639:Histidine