Bile acids, reversed micelles

The mechanism by which the lipolytic products pass from the micellar phase into the mucosal cell is unknown, and an extensive discussion of the possibilities is inappropriate here. Since lipolytic products are extensively absorbed whereas taurine-conjugated bile acids are not absorbed in jejunal perfusion experiments (23), and since exchange rates of lipolytic products between micelles are thought to be quite rapid (78), molecular collision of lipolytic products with the cell membrane, resulting in reversible or partially reversible adsorption, has been proposed as the mechanism of fat absorp-... 

Bile salts are natural and chiral anionic surfactants which form helical micelles of reversed micelle conformation. The first report on enantiomer separation by MEKC using bile salts was the enantioseparation of dansylated DL-amino acids (Dns-o,L-AAs) and, since then, numerous papers have been available. Nonconjugated bile salts, such as sodium cholate (SC) and sodium deoxycholate (SDC), can be used at pH > 5, whereas taurine-conjugated forms, such as sodium taurocholate (STC) and sodium taurodeox-ycholate (STDC), can be used under more acidic conditions (i.e., pH > 3). Several enantiomers, such as diltiazem hydrochloride and related compounds, carboline derivatives, trimetoquinol and related compounds, binaphthyl derivatives, Dhs-dl-AAs, mephenytoin and its metabolites, and 3-hydroxy-l,4-benzodiazepins have been successfully separated by MEKC with bile salts. In general, STDC is considered as the the most effective chiral selector among the bile salts used in MEKC. 

Shaw, R., Elliott, W., and Barisas, B. 1991, Estimation of critical micelle concentration of bile acids by reversed-phase high performance liquid chromatography. Mikrochim, Acta 3, 137. 

---