Characterization of metabolites of benz(j)aceanthrylene in faeces, urine and bile from rat

1. The excretion of benz[j]aceanthrylene (B[j]A) and the biotransformation products found in faeces, urine and bile of rat exposed to [H-3]-labelled B [j]A have been studied. 2. About 95% of the administered radioactivity was excreted within 7 days, 79% via faeces and 16% via urine, and most of the radioactivity in urine an d faeces was excreted within 2 days. 3. The B[j]A metabolites excreted between days 1 and 2, including those exc reted in bile during the first 5.5 h in a separate experiment, were further characterized by HPLC, UV and electrospray/atmospheric pressure chemical i onization mass spectrometry. 4. In faeces, bile and urine, hydroxylated B[j]A metabolites predominated. The major metabolites in faeces were B[j]A-1,2-dihydrodiol-8-hydroxy and B[ j]A-1,2-dihydrodiol-10-hydroxy. These metabolites were found as conjugated metabolites in the bile. The glucuronide conjugate of B[j]A-1,2-dihydrodiol -10-hydroxy was also a major metabolite in urine. Two sulphate conjugates o f oxidized B[j]A were detected in bile, a sulphate conjugate of a B[j]A-dih ydrodiol-phenol and B[j]A-1,2-dihydrodiol-10-sulphate. Trans-B[j]A-1,2-dihy drodiol was detected in urine, faeces and bile. 5. These findings support the hypothesis that epoxidation at the cyclopenta ring is an important biotransformation pathway for B[j]A in vivo. In addit ion to the characterized metabolites, a large fraction of polar compounds, possibly glutathione conjugates, was also excreted in urine and bile.