Structural effects of phenolic acids on the transepithelial transport of fluorescein in caco-2 cell monolayers.

The structural specificity of the monocarboxylic acid transporter (MCT) for the transport of phenolic acids was investigated by measuring the inhibitory effect on the fluorescein transport in Caco-2 cell monolayers. Although most of the monohydroxylated derivatives had an inhibitory effect, the di- and tri-hydroxylated ones did not. The methoxylated derivatives were more inhibitory than the hydroxylated ones in all the meta-substituted derivatives, suggesting that meta-hydroxylation of the substrate would decrease the affinity for MCT.