Metabolism of naturally occurring propenylbenzene derivatives. III. Allylbenzene, propenyl benzene, and related metabolic products.

The acidic and neutral urinary metabolites of allylbenzene, propenylbenzene, 1'-hydroxyallylbenzene, and cynnamyl alcohol were identified and related through a common metabolic scheme. The rat metabolizes allylbenzene to 1'-hydroxyallylbenzene which can rearrange to yield cinnamyl alcohol whick is further metabolized. This mechanism is proposed to account for the appearance of "propenyl type" metabolites from allylbenzene compounds. Propenylbenzene is oxidized to cynnamyl alcohol. Both 1'-hydroxyallylbenzene and cunnamyl alcohol are excreted unchanged in the neutral extract when given to rats. Allylbenzene and 1'-hydroxyallylbenzene yield basic ninhydrin-positive metabolites. Allylbenzene is first oxidized on the benzylic carbon to form 1'-hydroxyallylbenzene, which is further oxidized to form phenyl vinyl ketone, which condenses with the secondary amines piperidine and dimethylamine to form tertiary aminopropiophenones (Mannich bases). Analogous compounds, cinnamyl alcohol and propenylbenzene, do not yield Mannich base metabolites. This proposed metabolic scheme is consistent with the chemical mechanism operative in the synthesis of Mannich base from allylbenzene via chromic acid oxidation followed by amine addition.