Quantitative Examination of the Simple Micelle–Mixed Micelle Coexistence for the Taurocholate–Lecithin System by GP-HPLC
✍ Scribed by Hideo Naganuma; Chen-Lun Liu; Uday K. Jain; Yoichi Adachi; William I. Higuchi
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 142 KB
- Volume
- 189
- Category
- Article
- ISSN
- 0021-9797
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✦ Synopsis
ological conditions, when the lecithin-bile salt ratio was Gel-permeation, high-performance liquid chromatography (GPapproximately less than 0.6, substantial amounts of both HPLC) studies were conducted to quantify simple micelles and micellar species could coexist in the system. History has mixed micelles present in model biles. A TSK-gel G2000SW colproven this interpretation to be essentially correct. Moreover, umn was preequilibrated with a buffered mobile phase: phosphate consideration of the simple micelle-mixed micelle coexisbuffer, pH 7.4, 0.1 M NaCl, and 30 mM [ 14 C]taurocholate (TC). tence in model bile systems has greatly aided the physical Simulated biles with different TC and/or egg-yolk lecithin (L) chemical mechanistic understanding of the behavior of nalevels were then introduced onto the GP column. The injected tive bile and model biles in general: (a) in explaining the biles without L (TC alone) yielded positive peaks or negative kinetics of dissolution of cholesterol monohydrate (and, valleys (relative to the baseline) at Ç9.5 min, depending on the injected TC concentration. A theoretical mass balance equation therefore, of cholesterol gallstone dissolution) in bile (2quantitatively accounted for the observed simple micelle peaks 5) and (b) in interpreting the thermodynamic activity of (or valleys). When TC-L coexisting simple micelle-mixed micelle cholesterol in model biles (6-9).
model biles were injected onto the column, in addition to the
The principal papers quantifying the simple micellesimple micelle peaks at Ç9.5 min, mixed micelle peaks were obmixed micelle coexistence behavior have come from our served at retention times in the region Ç7.5 to 8.0 min. Here, laboratories (5, 10-12). These have all involved equilibalso, there was good mass balance between the expected and the rium dialysis (ED) measurements in bile salt-lecithin sysobserved TC peaks. The average molecular weights were estimated tems. Taken together, these papers represent all of the exas Ç28,000-45,000 Da for the mixed micelles and Ç5500 Da for isting quantitative data on the simple micelle-mixed micelle the simple micelles, respectively. The TC-to-L molar ratio (K) for coexistence behavior for the taurocholate (TC) -, taurothe mixed micelle peak showed a curvilinear decrease as a function chenodeoxycholate (TCDC) -, and tauroursodeoxycholate of L concentration and leveled off at around 1.5. These results are consistent with those obtained from previous equilibrium dialysis (TUDC) -lecithin (L) systems.
studies, although the K values from present studies are slightly
The purpose of the present study was to examine quantilower (Ç20%); a possible explanation for this discrepancy is pretatively the simple micelle -mixed micelle coexistence besented.