Studies in detoxication. 51. The determination of catechols in urine, and the formation of catechols in rabbits receiving halogenobenzenes and other compounds. Dihydroxylation in vivo

Abstract

A spectrophotometric method for the detn. of ether-soluble catechols in urine was studied. The method depends on the measurement at 580 m[mu]. of the blue color formed between cobalt salts and catechol in the presence of alkali. The color is given by many 1,2-dihydroxy compounds, including adrenaline. This method was applied to the detn. of catechols formed during the metabolism of fluoro-, chloro-, bromo-, iodo- and o-dichloro-benzene in the rabbit. Between 20 and 30% of the monohalogenobenzenes metabolized are converted into the corresponding 4-halogenocatechols which are excreted mainly in conjugated forms for 2-3 days after dosing. Some 8% of o-dichlorobenzene is dihydroxylated. The isomeric monochlorophenols and phenol are also oxidized to catechols to a small extent (0.5-4%). The halogenobenzenes also form small amts. (about 2-3%) of p-halogenophenols and traces of the o-phenols. These were detected mainly by paper chromato-graphy. The relation between mercapturic acid and o-dihydroxy-lation in these compounds is discussed, but no definite conclusions were reached. The formation of catechols from the halogenobenzenes need not be contrary to the free radical hypothesis of biological hydroxylation, although although other explanations are also feasible.