Reactive intermediates from 3-hydroxybenzo[a]pyrene and its glucuronide.

3-Hydroxybenzo[a]pyrene (3-OH-BaP) is oxidized by the horseradish peroxidase/H2O2 system to benzo[a]pyrene-3,6-quinone. In the presence of N-acetylcysteine one other product is also formed. This was identified by its chemical, and u.v., mass and n.m.r. spectral properties as 6-(H-acetyl-cystein-S-yl)-3-hydroxybenzo[a]pyrene (6-NAc-cys-3-OH-BaP). Replacement of the N-acetylcysteine by glutathione leads to the formation of a 3-OH-BaP-glutathione adduct. Enzymic hydrolysis of benzo[a]pyrene-3-glucuronide in the presence of N-acetylcysteine yields, in addition to 3-OH-BaP, a product which co-chromatographs with 6-NAc-cys-3-OH-BaP and has identical chemical and spectral characteristics.