Cyclopenta[c,d]pyrene: a highly mutagenic polycyclic aromatic hydrocarbon.

Abstract

A polycyclic aromatic hydrocarbon recently isolated from carbon black and identified as cyclopenta[c,d]-pyrene (CPP) is highly mutagenic. By the criteria of the Salmonella[typhimurium]/mammalian[rat]-microsome mutagenicity test, the mutagenic potency of CPP is equalled by only 2 other naturally occurring polycyclic aromatic hydrocarbons-benzo[a]pyrene and dibenz[a,c]anthracene. The potent mutagenicity of CPP is noteworthy for 2 reasons: CPP is a mutagenic polycyclic aromatic hydrocarbon without a bay-region and there is evvidence that it is distributed widely in the environment. Experimental observations and perturbational molecular orbital calculations showed that a mutagenic metabolite of CPP will be the 3,4-oxide. The carbonium ion derived from opening of CPP 3,4-oxide is identical to that derived from opening of benzo[a]pyrene 7,8-diol-9,10-oxide, the metabolite now thought to be an ultimate mutagenic and carcinogenic species.