Effects of a lysophosphatidylcholine and a phosphatidylcholine on the morphology of taurocholic acid-based mixed micelles as determined by small-angle X-ray scattering

摘要

We previously showed that Caco-2 cell absorption of -carotene from taurocholic acid (TA)-based mixed micelles differed depending on the composition of the micelles. In this study, the shapes and sizes of TA-based mixed micelles, that is, mixed micelles of TA, 1-oleoyl-rac-glycerol (MG), oleic acid (OLA), and either 1-palmitoyl-sn-glycero-3-phosphocholine (MPPC; i.e., a lysophospholipid) or 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC; i.e., a phospholipid) (60:3:1:0.75-12) were determined by using small-angle X-ray scattering (SAXS). We found that increasing the ratio of MPPC in mixed micelles of TA, MG, OLA, and MPPC was responsible for the previously observed enhanced -carotene absorption by Caco-2 cells and changed the micelle shape from core-shell spherical to core-shell ellipsoidal. In contrast, increasing the ratio of POPC in mixed micelles of TA, MG, OLA, and POPC was responsible for the suppressed -carotene absorption by the cells, changed the micelle shape from core-shell spherical to core-shell ellipsoidal to core-shell cylindrical, and caused a rapid increase in micelle volume. These results will be useful for understanding the mechanisms that mediate -carotene absorption by cells and for developing technologies to improve the intestinal absorption of lipophilic components of drugs and nutrients.