Solubility of cholesterol in vitro promoted by oxidation products of cholesterol.

Compounds promoting the solubility of cholesterol could have a role in preventing its crystallisation and accumulation in tissue and in body fluids. A small quantity of phosphatidylcholine added to a supersaturated solution of cholesterol in a triglyceride oil has limited capacity to maintain solubility of cholesterol. Small quantities of oxidation products of cholesterol (oxysterols) have no material effect on the solubility of cholesterol in this system. However, the combination of phosphatidylcholine and oxysterols effectively maintains cholesterol in stable solution. In aqueous medium, the capacity of phosphatidylcholine to solubilise a molar excess of cholesterol is greatly increased by oxysterols. Oxidation products of cholesterol and phosphatidylcholine acting synergistically enhance enormously the solubility of cholesterol both in supersaturated solution in a triglyceride oil and in aqueous medium.