CHOLEST-3,5-DIEN-7-ONE FORMATION IN PEROXIDIZED HUMAN PLASMA AS AN INDICATOR OF LIPOPROTEIN CHOLESTEROL PEROXIDATION POTENTIAL

Lipoprotein peroxidation susceptibility is routinely evaluated using p roducts of unsaturated fatty acids as markers (e.g., malonaldehyde). T he significance and factors influencing peroxidation of cholesterol mo iety of lipoproteins are relatively unknown due to lack of a reliable marker product which can be measured easily. Under the influence of Cu 2+ ions, the major product of lipoprotein cholesterol peroxidation (is olated after saponification) was cholest-3-5-dien-7-one (CSD). Apart f rom gas-liquid chromatography, this compound lends itself for measurem ent by alternative methods. Due to lack of the 3 beta-hydroxyl group, CSD was separated from the rest of the oxysterols and cholesterol by p assing through digitonin-coated silica-gel G and its concentration was determined by absorption at 283 nm. The recovery of CSD by this metho d exceeded by 87%. The formation of CSD was also sensitive to vitamin E and therefore could be used as an index of lipoprotein cholesterol s usceptibility to peroxidation.