Cholesterol, autoxidation

Smith, L.L. In "Cholesterol Autoxidation" Plenum Press New York, 1981. 

Figure 18.2. Cholesterol autoxidation initiated by peroxy (LOO ) or alkoxyl (LO ) radicals arising from peroxidation of polyunsaturated fatty acids (LH). Compounds are as follows (1) CHOL (2) 7-CHOL (3) CHOO (4) 7a-OOH (5) 7fLOOH (6) CHO (7) 7a-OH (8) 7(3-OH (9) 7-keto (10) 7-keto-3,5-dien. For abbreviations, see Table 18.1.

Rose-Sallin, C., Huggett, A.C., Bosset, J.O., Tabacchi, R., Fay, L.B. 1995. Quantitation of cholesterol oxidation products in milk powder using [2Hy] cholesterol to monitor cholesterol autoxidation. J. Agric. Food Chem. 43, 935-941. 

Smith, L.L. 1987. Cholesterol autoxidation 1981-1986. Chem. Phys. Lipids 44, 87-125. 

There is one more aspect of the problem under consideration. Cholesterol autoxidized on the air with formation epoxides, ketones, hydroperoxy- and hydroxy-derivatives [26] (Figure 9). 

Even less well understood than MA is the possible occurrence of cholesterol oxidation products in foods and their health significance. It seems clear that some of the products of cholesterol autoxidation are atherogenic. Much more research will be required to establish or refute their proposed carcinogenic properties. Methods for the determination of cholesterol oxidation products in foods and studies to establish levels of occurrence, if any, are most urgently needed. Further studies on antioxidants and procedures for the inhibition of oxidation are also needed. It is difficult to overstate the potential importance to the animal products industry of studies on quantification of cholesterol oxides in food products. Concern about this area of research is becoming widespread (47,48). 

Foods of animal origin are suspected to contain some amount of COP formed by autoxidation. Cholesterol autoxidation is a well-established free radical process that involves the same chemistry that occurs for the oxidation of unsaturated lipids. Cholesterol contains one double bond at the carbon-5 position therefore, the weakest points in its structure are at the carbon-7 and carbon-4 positions. However, due to the possible influence of the hydroxyl group at carbon-3 and the tertiary carbon atom at carbon-5, the carbon-1 position is rarely attacked by molecular oxygen, and therefore the abstraction of an allylic hydrogen predominantly occurs at carbon-7 and gives rise to a series of A and B ring oxidation products. In the chain reaction,... 

Smith, L.L. (1981). Cholesterol Autoxidation, Plenum Press, New York. 

Wasilchuk, B.A., Le Quesne, P.W., and Vouros, P. (1992). Monitoring cholesterol autoxidation processes using multideuterated cholesterol. Anal. Chem., 64, 1077. 

Figure 2.19. Products of cholesterol autoxidation ( O ) and singlet oxygenation ( O ).

Liere, P., Pianos, A., Eychenne, B., Cambourg, A., Bodin, K., Griffiths, W., Schumacher, M., Baulieu, E.E., Sjdvall, I (2009) Analysis of pregnenolone and dehydroepiandros-terone in rodent brain cholesterol autoxidation is the key. 

Karu, K., Turton, J., Wang, Y. and Griffiths, W.J. (2011) Nano-liquid chromatography-tandem mass spectrometry analysis of oxysterols in brain Monitoring of cholesterol autoxidation. Chem. Phys. Lipids 164,411-424. 

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