The epimeric 20-hydroperoxy-5-pregnen-3 -ols: thermal and enzymatic decomposition

Tracer studies of cholesterol degradation induced by ionized gases

Multiple molecular layers of cholesterol-4-C14 were bombarded in an ultra high vacuum system with various excited molecular, ionic and atomic species derived from oxygen, methane and carbon monoxide. The degradation products were analyzed by thin layer chromatography followed by autoradiography and the decomposition patterns were compared with those obtained from the autoxidation of cholesterol. Bombardment with excited and ionized species derived from both molecular oxygen and carbon monoxide leads to a number of known polar cholesterol oxidation products, similar to those formed during the natural oxidation of cholesterol. In contrast, species derived from methane lead only to the formation of products less polar than cholesterol with none of the established autoxidation products at detectable levels.

Cholesterol autoxidation: identification of the volatile fragments

The volatile fragments of air-aged cholesterol were analysed by means of gas chromatography-mass spectrometry; The following fourteen compounds were identified: ethanol, acetic acid, acetone, 2-methylpropene, 2-methyl-1-propanol, 2-methyl-2-propanol, 2-butanone, 2-methylpropionic acid, 2-methyl-2-butanol, 2-pentanone, 3-methyl-2-butanone, 2-methyl-1-pentene, 2-methyl-2-pentanol, and 2-methyl-4-penten-2-ol. Their formation via decomposition of initially formed sterol hydroperoxides is discussed.