Abstract
The metabolic fate of shikimic acid has been investigated in the rat. Shikimic acid was not observed to be metabolised by mammalian tissues, instead the compound appears to be metabolised via a multiplicity of microbial-dependent pathways in the gastrointestinal tract. Products of microbial metabolism were excreted unchanged or subsequent to further biotransformation in the tissues. Both in vitro and in vivo, shikimic acid was shown to be converted to cyclohexanecarboxylic acid by gastrointestinal microorganisms. The formation, absorption and further metabolism of the latter accounted for the observed urinary excretion of hippuric acid, hexahydrohippuric acid and 3,4,5,6-tetrahydro-hippuric acid after oral administration of shikimic acid. Liver perfusion studies confirmed that the liver is one of the major organs responsible for the metabolism of cyclohexanecarboxylic acid in the rat. Additional microbial pathways gave rise to the production of both cis- and trans- 3,4-dihydroxycyclohexanecarboxylic acids and a urinary conjugate of catechol.