Abstract |
The ability of reduced polycyclic aromatic hydrocarbons to be converted to their fully aromatic forms by the microsomal cytochrome P-450 mixed-function oxidases may assist in the explanation of the mutagenic and tumorigenic activities of these agents. The metabolic conversion of 9,10-dihydrobenzo(a)pyrene (9,10-DHB(a)P) to benzo(a)pyrene (B(a)P) and 9- and/or 10-hydroxy-9,10-DHB(a)P (OH-9,10-DHB(a)P) was quantitatively measured. In beta-naphtho-flavone-induced rat liver microsomes, 9,10-DHB(a)P was metabolized to B(a)P with a specific activity of 1.51 nmol B(a)P formed/min/mg microsomal protein. The formation of B(a)P was directly related to incubation time and microsomal protein concentration. Similarly, 9,10-DHB(a)P was converted to OH-9,10-DHB(a)P with a specific activity of 4.48 nmol OH-9,10-DHB(a)P formed/min/mg microsomal protein. Its formation was directly related to incubation time and microsomal protein concentration. The possibility of OH-9,10-DHB(a)P as a metabolic intermediate to B(a)P is discussed. (Copyright (c) 1993 Elsevier Scientific Publishers Ireland Ltd.) |