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The urinary metabolites of isosafrole (1,2-methylenedioxy-4-propenylbenzene) and dihydrosafrole (1,2-methylenedioxy-4-propylbenzene) in the rat were identified using gas chromatographic mass spectrometric methods. Additionally, the amounts of the individual metabolites excreted were determined gas chromatographically. Metabolite excretion was 89% (isosafrole) and 97% (dihydrosafrole) of the dose in 72 h. Although isosafrole was metabolized by allylic hydroxylation and via the epoxide-diol pathway, demethylenation leading mainly to 1,2-dihydroxy-4-propenylbenzene was by far the most prominent reaction. This was similarly true with dihydrosafrole which was metabolized mainly to 1,2-dihydroxy-4-(1-propyl) benzene. The total amount of demethylenated metabolites formed were 92% (isosafrole) and 95% (dihydrosafrole) of the identified material.

The urinary metabolites of flavanone in the rate were investigated using a gas chromatographic mass spectrometric method employing an OV-1 capillary column. Forty-three metabolites were detected and the most prominent of these were identified. The most common metabolic reactions were reduction of the keto group and hydroxylation at the 3- or 6-positions. Little hydroxylation occurred in ring B. The major metabolites were flavan-4 alpha-ol, trans-3-hydroxyflavan-4 beta-ol, 6-hydroxyflavanone and 6-hydroxyflavan-4 beta-ol. Gas chromatography analysis of underivatized flavanone metabolites, especially with stainless steel columns, results in the formation of dehydrated products including flavone, flav-3-ene and flavanone itself.