Lipids

, Volume 45, Issue 9, pp 855–862 | Cite as

Phytosterol Ester Constituents Affect Micellar Cholesterol Solubility in Model Bile

  • Andrew W. Brown
  • Jiliang Hang
  • Patrick H. Dussault
  • Timothy P. Carr
Original Article

Abstract

Plant sterols and stanols (phytosterols) and their esters are nutraceuticals that lower LDL cholesterol, but the mechanisms of action are not fully understood. We hypothesized that intact esters and simulated hydrolysis products of esters (phytosterols and fatty acids in equal ratios) would differentially affect the solubility of cholesterol in model bile mixed micelles in vitro. Sodium salts of glycine- and taurine-conjugated bile acids were sonicated with phosphatidylcholine and either sterol esters or combinations of sterols and fatty acids to determine the amount of cholesterol solubilized into micelles. Intact sterol esters did not solubilize into micelles, nor did they alter cholesterol solubility. However, free sterols and fatty acids altered cholesterol solubility independently (no interaction effect). Equal contents of cholesterol and either campesterol, stigmasterol, sitosterol, or stigmastanol (sitostanol) decreased cholesterol solubility in micelles by approximately 50% compared to no phytosterol present, with stigmasterol performing slightly better than sitosterol. Phytosterols competed with cholesterol in a dose-dependent manner, demonstrating a 1:1 M substitution of phytosterol for cholesterol in micelle preparations. Unsaturated fatty acids increased the micelle solubility of sterols as compared with saturated or no fatty acids. No differences were detected in the size of the model micelles. Together, these data indicate that stigmasterol combined with saturated fatty acids may be more effective at lowering cholesterol micelle solubility in vivo.

Keywords

Phytosterols Phytosterol esters Cholesterol absorption Bile Mixed micelle Plant sterol Plant stanol 

Abbreviations

DHA

Docosahexaenoic acid

EPA

Eicosapentaenoic acid

GC

Gas chromatography

HDL

High-density lipoprotein

LDL

Low-density lipoprotein

N2

Molecular nitrogen

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Copyright information

© AOCS 2010

Authors and Affiliations

  • Andrew W. Brown
    • 1
  • Jiliang Hang
    • 2
  • Patrick H. Dussault
    • 2
  • Timothy P. Carr
    • 1
  1. 1.Department of Nutrition and Health SciencesUniversity of Nebraska-LincolnLincolnUSA
  2. 2.Department of ChemistryUniversity of Nebraska-LincolnLincolnUSA

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