Auto-oxidation cholesterol

Peroxidation is also catalyzed in vivo by heme compounds and by lipoxygenases found in platelets and leukocytes. Other products of auto-oxidation or enzymic oxidation of physiologic significance include oxysterols (formed from cholesterol) and isoprostanes (prostanoids). 

Under the title Cholesterol is Stable , a sample purified via the dibromide in 1937, and stored in the dark, is reported to contain no detectable trace of impurity when examined recently. Ordinary commercial samples, however, are highly susceptible to auto-oxidation during storage- Compounds isolated from aged cholesterol include the 20a-, 24R-, 24S-, and 25-hydroperoxy-deriva-tives. ... 

Chemically wool wax is a complex mixture of esters, diesters and hydroxy esters of high molecular weight lanolin alcohol and acids. The lanolin alcohol consists of three main types - aliphatic alcohols, sterols (such as cholesterol) and trimethyl sterols (such as lanosterols). The lanolin acid consists of four main types - normal, iso, anteiso and hydroxy acids. On exposure to the environment wool readily undergoes auto-oxidation. The reaction product (oxidised wool wax) be-... 

Assay of the enzyme activity is complicated by the fact that 7a-hydroxylation of cholesterol also may occur due to auto-oxidation or secondary to lipid preoxidation. In addition it is difficult to equilibrate exogenous cholesterol with endogenous microsomal cholesterol. 

Similar chromatographic conditions using two silica columns in tandem together with simple binary solvent systems of hexane-2-pro-panol (99 1, 24 1, or 9 1), hexane-butanol (99 1) or 2,2,4-trimeth-ylpentane-2-propanol (499 1) have been used for the resolution of a number of the auto-oxidation products of cholesterol (Ansari and Smith, 1979). The authors concluded that while the required separations could be achieved by normal phase chromatography, the use of ODS stationary phases offered added versatility when investigating... 

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