Improvement of the Solubility and Intestinal Absorption of Curcumin by N-Acyl Taurates and Elucidation of the Absorption-Enhancing Mechanisms

Abstract

In this study, the effects of N-acyl taurates (NATs) on the intestinal absorption of curcumin (CUR), a water-insoluble and poorly absorbed compound, were examined in rats. Sodium methyl lauroyl taurate (LMT) and sodium methyl cocoyl taurate (CMT) were the most effective in increasing the solubility and intestinal absorption of CUR. The intestinal membrane toxicity of the NATs was also evaluated by measuring the activity of lactate dehydrogenase (LDH), a toxicity marker. NATs did not increase the activity of LDH, suggesting that they may be safely administered orally. We further elucidated the absorption-enhancing mechanisms of NATs by using Caco-2 cells. In cellular transport studies, LMT and CMT reduced the transepithelial electrical resistance value of Caco-2 cells and increased the transport of 5(6)-carboxyfluorescein and CUR. Hence, the intestinal absorption enhancement by LMT and CMT was attributed to the synergistic effect of higher solubility and greater permeability of the cell layer towards CUR in the presence of the surfactants. In summary, co-administration of CUR with either LMT or CMT is a simple and effective method to enhance oral delivery of CUR.

Graphical Abstract