CELLULAR BIOCHEMISTRY OF OXYSTEROLS DERIVED FROM THE DIET OR OXIDATION IN-VIVO

Oxidized derivatives of cholesterol, known as oxysterols, are present in the diet as contaminants of cholesterol-containing foods. They can enter the circulation through the diet or they are generated through p eroxidation of lipoproteins or enzymatic oxidation of cholesterol. Lik e cholesterol, oxysterols are transported in serum with lipoproteins b ut, unlike cholesterol, they may also be transported by serum albumin. This additional means of transport may allow for more efficient remov al of cellular sterols or transfer between tissues. It has been sugges ted that the physiologic regulation of cholesterol metabolism may be t hrough generation of oxysterols. In addition, oxysterols potentially p lay a role in aspects of various diseases such as atherosclerosis and cancer, either as contributory or protective agents, most likely throu gh their action as potent modulators of cholesterol metabolism and/or their direct effects on membrane structure and function. Thus, these c ompounds may represent normal physiologic processes as well as patholo gical ones and strategies to enhance or diminish oxysterol levels may prove useful in the future.