Effect of Certain Compounds on Solubility of Cholesterol in Coconut Oil.

A simple assay method has been developed for determining the effect of various compounds on the solubility of cholesterol in oils. The method depends on the counting of an aliquot of supernatant solution following the equilibration of oil, an excess of cholesterol-4-C14, and compound studied with respect to influence on the solubility of cholesterol. It was confirmed that the solubility of cholesterol in coconut oil is decreased by the presence of β-sitosterol. The effect is specific as far as a large number of sterols is concerned. The solubility of cholesterol in coconut oil is decreased by the presence of certain dicarboxylic acids and methyl substituted dicarboxylic acids, as well as by imidazole. Active acids thus far discovered in order of decreasing activity are the following: 5,5-dimethylazelaic acid; 4,4-dimethylpimelic acid; 2,2-dimethylglutaric acid; pimelic acid; methylmalonic acid; glutaric acid; 2;2′-dimethylsuccinic acid; 2-methylpimelic acid; 3,3-dimethylglutaric acid; 2,2-dimethylsuccinic acid; and 2-meth-ylsuccinic acid. Approximately 100 miscellaneous compounds, including many other dicarboxylic acids and imidazole derivatives, are not associated with any decrease in the solubility of cholesterol in coconut oil. Free fatty acids in relatively small amounts increase the solubility of cholesterol in coconut oil.