Metabolism of polycyclic compounds. 26. The hydroxylation of some aromatic hydrocarbons by the ascorbic acid model hydroxylating system and by rat-liver microsomes

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Abstract
The products of the hydroxylations of some aromatic hydrocarbons in the rat-liver-micro-somal enzyme system and the ascorbic acid-Fe ion-oxygen model system were compared. With the simpler hydrocarbons the products were similar, whereas with the more complex hydrocarbons less reaction occurred at the more reactive bonds of the molecules in the chemical than in the enzyme reactions. Naphthalene was converted into 1-hydroxy-, 2-hydroxy- and 1, 2-dihydro-l, 2-dihydroxy-naphthalene by both systems. An unidentified metabolite that yielded 1-hydroxy-naphthalene with acid was detected with the enzyme. Anthracene was hydroxylated to 1, 2-dihydro-l, 2-dihydroxyanthracene in both systems, but 1- and 2-hydroxyanthracene were not formed. 9, 10-Anthraquinone was detected in the chemical but not in the enzymic system. Phenan-threne was converted into 1-, 2-, 3- and 4-hydroxyphenanthrene and 1, 2-dihydro-l, 2-dihydroxy-and 3, 4-dihydro-3, 4-dihydroxy-phenan-threne in both systems. 9, 10-Dihydro-9, 10-dihydroxyphenanthrene was also a product of both hydroxylations, but the amount formed in the chemical was much less than that formed in the enzymic hydroxylation. Small amounts of 9-hydroxyphenanthrene were formed in the chemical oxidation. Pyrene was converted into 1-hydroxypyrene, 4, 5-dihydro-4, 5-dihydroxypyrene and 1, 6- and 1-8-pyrenequinone in both hydroxylations, but the amount of the dihydrodihydroxy compound formed in the chemical oxidation was small. Benz[a]anthracene was oxidized in the chemical system to 1-, 2-, 3- and 4-benz[a]anthracene and to 1, 2-dihydro-l, 2-dihydroxy- and 3, 4-dihydro-3, 4-dihydroxy-benz[a]anthracene, whereas the enzymic system yielded mainly 8, 9-dihydro-8, 9-dihydroxybenz[a]anthracene. Small amounts of 3- and 4-hydroxybenz[a]anthracene were formed in the enzymic system together with trace amounts of l-hydroxybenz[a]anthracene and a compound that appeared to be 1, 2-dihydroxybenz[a]anthracene. Both systems yielded 7, 12-benz[a]anthracenequinone and small amounts of 5, 6-dihydro-5, 6-dihydroxybenz[a]anthracene.