Formation of pentachlorophenol as the major product of microsomal oxidation of hexachlorobenzene

On incubation of [14C]-hexachlorobenzene with microsomes from livers of rats induced with hexachlorobenzene, the major product (80-90%) was pentachlorophenol. The only other detectable metabolite, tetrachlorohydroquinone (4-15%), was presumably formed from pentachlorophenol. A considerable amount of radioactivity (5-10% of the amount of extracted metabolites) was covalently bound to protein. Microsomes derived from male hexachlorobenzene--induced rats gave by far the highest conversion (approx. 1% of substrate). Microsomes from female hexachlorobenzene--induced rats were 3 times less efficient. Microsomes from untreated and 3-methyl-cholanthrene--treated animals gave less than 5% of the amount of pentachlorophenol formed by microsomes from hexachlorobenzene--induced male rats, while phenobarbital and aroclor 1254-induction resulted in formation of 51% and 34% respectively.