Epoxide intermediates in the metabolism of naphthalene by the rat

Twenty-one oxygenated metabolites of naphthalene have been isolated from rat urine and characterized by gas chromatography and gas chromatography and gas chromatography-mass spectrometry. Studied with naphthalene-1,4-d2 confirmed that the compounds characterized by GC/MS were derived from naphthalene. The structures of a number of metabolites were confirmed by synthesis. All but one of these metabolites were formed by processes involving epoxidation, and the structures of the metabolites support the hypothesis that multiple epoxides and a cyclic peroxide are involved in the in vivo metabolism of naphthalene by the rat. The evidence provided by this and our previous studied indicates that the anti-diepoxide of naphthalene is a mammalian metabolite. Ten methylthio metabolites were isolated in earlier studies. Excluding mercapturic acids, conjugates, and related compounds, the total number of isolated compounds is now 31, and several additional compounds must have been present as intermediates. The structures of epoxide intermediates are indicated by precursor-product relationships.