Food and Biodynamic Chemistry Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Miyagi, 980-0845, Japan.
Department of Cell Biology, Division of Host Defense Mechanism, Tokai University School of Medicine, Isehara, Kanagawa, 259-1193, Japan.
Sci Rep. 2018 Jun 14;8(1):9116. doi: 10.1038/s41598-018-27455-5.
Oxidation of squalene (SQ) causes a decline in the nutritional value of SQ in foods, as well as an accumulation of SQ oxidation products in skin lipids which lead to adverse skin conditions. However, mechanistic insights as to how SQ is oxidized by different oxidation mechanisms have been limited, and thus effective measures towards the prevention of SQ oxidation have not been identified. In this study, we oxidized SQ by either singlet oxygen oxidation or free radical oxidation, and monitored the formation of the six SQ monohydroperoxide (SQOOH) isomers, the primary oxidation products of SQ, at the isomeric level. While singlet oxygen oxidation of SQ resulted in the formation of similar amounts of the six SQOOH isomers, free radical oxidation of SQ mainly formed two types of isomers, 2-OOH-SQ and 3-OOH-SQ. The addition of β-carotene during singlet oxygen oxidation, and the addition of α-tocopherol during free radical oxidation lead to a dose-dependent decrease in the formation of SQOOH isomers. Such results suggest that the analysis of SQOOH at the isomeric level allows for the determination of the cause of SQ oxidation in various samples, and provides a foothold for future studies concerning the prevention of SQ oxidation.
角鲨烯（SQ）氧化会降低食品中 SQ 的营养价值，并导致皮肤脂质中 SQ 氧化产物的积累，从而导致皮肤状况恶化。然而，对于 SQ 如何通过不同的氧化机制被氧化的机制性见解有限，因此，尚未确定预防 SQ 氧化的有效措施。在这项研究中，我们通过单线态氧氧化或自由基氧化来氧化 SQ，并在同分异构水平上监测 SQ 的主要氧化产物——六种 SQ 单氢过氧化物（SQOOH）异构体的形成。虽然 SQ 的单线态氧氧化导致形成了数量相似的六种 SQOOH 异构体，但 SQ 的自由基氧化主要形成了两种类型的异构体，即 2-OOH-SQ 和 3-OOH-SQ。在单线态氧氧化过程中添加 β-胡萝卜素，以及在自由基氧化过程中添加 α-生育酚，都会导致 SQOOH 异构体形成的剂量依赖性下降。这些结果表明，在同分异构水平上分析 SQOOH 可以确定各种样品中 SQ 氧化的原因，并为未来有关 SQ 氧化预防的研究提供立足点。
