Whereas the initial events of cholesterol autoxidation involve two distinct modes of reaction, alcohol dehydrogenation to the 3-ketone 6 and hydroperoxide formation yielding 7-,17-,20-,22-,24-,25, and 26-hydroperoxides, it is in the subsequent transformations of these initial products that the vastly complex mixtures of cholesterol autoxidation products obtain. No set number of autoxidation products is realistic, for only oxidation products generally less mobile than cholesta-3,5-dien-7-one (10) but more mobile than 5a-cholestane-3β,5,6β-triol (13) have been systematically examined. A substantial amount of more mobile material and more polar, acidic material from air-aged cholesterol has not received attention . A formal count of cholesterol autoxidation products from a naturally air-aged cholesterol sample resolved by two-dimensional thin-layer chromatography numbered thirty-two , and the number of discrete subsequent alteration products derived from the acknowleged initial products described in this chapter runs to forty-six, thus accounting for approximately sixty-six steroid oxidation products. Not all of these have been isolated from or detected in air-aged cholesterol, but from the observed transformations of each initial product under relatively mild conditions which simulate natural aging processes one may project that each recognized product might be present among the myriad of yet unidentified products.
KeywordsThermal Decomposition Subsequent Transformation Chapter Versus Hydroperoxide Formation Autoxidation Product
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