| Abstract
| - The effect of riboflavin or fatty acid methyl esters on cholesterol photooxidation was studied. Samplescontaining cholesterol, either alone or in combination with riboflavin or fatty acid methyl esters, wereilluminated at 25 °C in an incubator for 28 days. The various cholesterol oxidation products (COPs)and cholesterol were analyzed by gas chromatography−mass spectrometry (GC−MS), and riboflavinwas determined by HPLC. Results showed that the presence of riboflavin or fatty acid methyl estersfacilitated production of COPs and degradation of cholesterol, and the degradation fits a first-ordermodel. The COPs formed during light storage included 7α-OH, 7β-OH, 7-keto, 3,5-cholestadien-7-one, 5,6α-EP, and 5,6β-EP. The addition of riboflavin caused formation of 3,5-cholestadien-7-onethrough dehydration of 7-keto, whereas in the presence of docosahexaenoic acid methyl ester, theformation of 5,6α-EP or 5,6β-EP was favored. Riboflavin was more effective for generation of COPsthan fatty acid methyl esters. Keywords: Riboflavin; fatty acid methyl ester; cholesterol photooxidation; GC−MS
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