ORIGIN, METABOLISM, AND ADVERSE HEALTH-EFFECTS OF CHOLESTEROL OXIDATION-PRODUCTS

Cholesterol oxidation products (COP), also called oxysterols, enter th e organism by intake of COP-containing foodstuff or are generated in v ivo by enzymatic or non-enzymatic oxidation (peroxidation) of choleste rol. COP are transported in lymph and blood with lipoproteins (mainly fatty acyl monoesters at the 3 beta-position) or bound to albumin. As being substrates for acyl CoA:choresterol acyltransferase (ACAT), leci thin:cholesterol acyltransferase (LCAT), and cholesteryl ester transfe r protein (CETP), COP are esterified and exchanged between lipoprotein s and are distributed in the whole organism. Kupffer cells and hepatoc ytes are the target cells for COP transformation and excretion via bil e secretion. Regarding biological activities, COP reveal widespread ef fects on cholesterol metabolism as well as on structure and function o f cellular membranes. Throughout their actions, COP were shown to be c ytotoxic but they were also suggested to be regulatory agents. Their d etrimental part in atherogenesis seems to be still underestimated, whi le valid data on the role of COP in carcinogenesis are still missing.