PHYSICOCHEMICAL PROPERTIES OF FATTY-ACIDS FOR ASSESSING THE THRESHOLDCONCENTRATION TO ENHANCE THE ABSORPTION OF A HYDROPHILIC SUBSTANCE

The effects of natural and non-natural fatty acids on enhancing the ab sorption of a hydrophilic marker through a human epithelial cell (Caco -2) monolayer were measured to elucidate the properties of the fatty a cids. Fatty acids from C9 to C14 enhanced the absorption depending on the concentration and the carbon chain length. Those fatty acids with longer chains gave a higher permeability coefficient at low concentrat ions and a lower toxicity than those with shorter chains. The surface energy lowering coefficient (SELC), an intrinsic physico-chemical prop erty, and the critical micellar concentration (CMC) were good criteria for identifying the threshold concentrations of a fatty acid to signi ficantly enhance absorption.