The absorption and metabolism of methyl cinnamate

Analysis of the gut contents of rats killed at intervals after dosage with methyl cinnamate or cinnamic acid suggested that both ester and acid were rapidly absorbed; at no time was more than 5% of the dose detected in the lower part of the gut. Not more than 9% of the administered methyl cinnamate was detected in the stomach as cinnamic acid whereas at least 40% of the small amounts of the dosed ester detected in the lower part of the gut was present as cinnamic acid. No ester was detected in the peripheral blood of dosed rabbits or rats and only traces were detected in portal and heart blood samples taken from dosed rats. Cinnamic acid and methanol were readily detected in the blood of rabbits and rats which had been dosed with methyl cinnamate. No qualitative or significant quantitative difference was detected in the metabolism of the ester as compared with the parent acid. In addition to the metabolites of cinnamic acid described in the literature p-hydroxyhippuric acid was excreted as a minor metabolite of both cinnamic acid and methyl cinnamate.