Enhanced bioavailability of alpha-lipoic acid by complex formation with octenylsuccinylated high-amylose starch.

An aqueous dispersion of alpha-lipoic acid (ALA) using octenylsuccinic anhydride-modified high-amylose starch (OS) was prepared, and thermal stability and cellular bioavailability of ALA were compared with those prepared using native high-amylose starch (HA) and beta-cyclodextrin (ß-CD). The ALA was homogeneously dispersed via the encapsulation of V-type amylose helices. In comparison with HA and ß-CD, OS exhibited a higher ALA absorption in Caco-2 cells, indicating the OS facilitated the intestinal epithelial transport of ALA. Oral administration of the encapsulated ALA in-vivo resulted in a higher maximum ALA plasma concentration and extended the terminal half-life by 30-40%. The area under the plasma concentration vs. time for the administration of ALA complexed by OS was 50% larger than that by HA, indicating the effectiveness of OS in enhancing the oral bioavailability of ALA. These results indicate that OS is an efficient carrier for ALA in oral delivery and bioavailability.