114E-9 |
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C.-C. J. Huang, Division of Environmental Health and Occupational Medicine, National Health Research Institutes, 100 Shih-Chuan 1st Rd., San Ming District, Kaohsiung City, 807, Taiwan and J. S. GODBER, Dept. of Food Science, Louisiana State Univ. Agricultural Center, 111 Food Science Bldg., Baton Rouge, LA 70803-4200. One potential functionality of g-oryzanol is its hypocholesterolemic capacity, as has been reported in numerous human and animal studies. We hypothesize that g-oryzanol may cause this effect by 1) affecting the stability of micelles containing both free and esterified forms of cholesterol, or by 2) influencing the function of the pancreatic enzyme, cholesterol esterase (CEase), and therefore the availability of total cholesterol for uptake into intestinal cells. Our objective was to develop an in vitro human intestinal cell model and use it to investigate the possible mechanisms of hypocholesterolemic capacity of g-oryzanol. Micellar solutions containing cholesterol or cholesteryl oleate with or without g-oryzanol were prepared using oleic acid, 1-monolein, lecithin and sodium taurocholate in buffer or culture medium. A human large intestinal cell line, C2BBe1 (ATCC CRL-2102), was used to study cholesterol uptake. Appropriate assays were used to test cytotoxicity for all test solutions applied to cells. Gas chromatography coupled with mass spectrometry was used to determine cholesterol concentrations. When cholesterol and g-oryzanol were preincubated for up to 6 hours before being applied to cells, cholesterol uptake into cells tended to decrease in a time-dependent manner. Six-hour preincubation significantly decreased cholesterol uptake to a level equivalent to the control (p<0.05). Preincubation of cholesteryl oleate with g-oryzanol at 37oC for 1 hour resulted in a trend towards lower cholesterol uptake (p=0.1546). Thus, micellar solubility of cholesteryl oleate or decreased availability of cholesteryl oleate for hydrolysis may have decreased cholesterol uptake. The inhibitory effect of g-oryzanol on CEase activity was not significant. Possible mechanisms for the hypocholesterolemic capacity of g-oryzanol could be 1) g-Oryzanol may affect the availability of cholesteryl esters for CEase-facilitated hydrolysis by reducing the micellar solubility of cholesteryl esters. 2) g-Oryzanol may affect the availability of free cholesterol for uptake by decreasing its micellar solubility.
Session 114E, Nutraceuticals & Functional Foods: Bioactivity measurement and mechanism
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