Inhibitory activities of vitamins on 7-ketocholesterol formation in both chemical model systems and beef patties

Abstract

Cholesterol Oxidation Products (COPs), produced by Cholesterol oxidation, are a family of oxidative products generated in high-temperature processing and prolonged storage. COPs could be differentiated into two distinct origins – enzymatic and non-enzymatic source. They are implicated in various food sources, and known to exert certain chemical effects like toxicity, HMG-COA reductase inhibition and atherogenesis effect on human. Considerable researches were conducted to develop strategies as to reduce the associated risk. Yet, direct evidence regarding their effects on COPs formation is still lacking. The formation pathways of COPs have partially elucidated. However, there is still controversy over the inhibition mechanism on COPs formation. The objective of the present study is to identify potent inhibitors of COPs formation from 15 vitamins using chromatographic methods in beef patties. Moreover, the roles of pyridoxamine (the most potent inhibitors) in the formation of 7-ketocholesterol is characterized. The detailed mechanism involved in cholesterol oxidation model system is elucidated. To conclude, vitamin C, A, E and PM can significantly lower the formation of 7-ketocholesterol. Their antioxidant activities only make minor contribution to their inhibitory activities. Their inhibitory activities are mainly mediated via their direct participation in Cholesterol oxidation: direct trapping of the final secondary oxidative product – 7-ketocholesterol.