Food and Biodynamic Chemistry Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Miyagi, Japan.
R&D Laboratories, KOSÉ Corporation, Tokyo, Japan.
Ann N Y Acad Sci. 2021 Sep;1500(1):112-121. doi: 10.1111/nyas.14615. Epub 2021 May 31.
Previous studies suggest that squalene (SQ) in sebum is oxidized by a photooxidation mechanism (i.e., singlet oxygen oxidation) to create SQ hydroperoxide (SQOOH), a compound that causes adverse skin conditions. However, oxidation of other lipids in sebum, such as linoleic acid (LA), has not been fully understood. Elucidating their oxidation, especially its mechanisms, may lead to a further understanding of the relationship between sebum oxidation and skin conditions. In this study, using HPLC-MS/MS, we aimed to detect LA hydroperoxide (LAOOH) directly from sebum and identify the oxidation mechanism of LA in sebum through analysis of LAOOH isomers. We developed extraction and HPLC-MS/MS analysis conditions that can sufficiently quantify each LAOOH isomer in sebum. Using this method, LAOOH was detected in samples from healthy individuals, demonstrating the presence of LAOOH in human sebum. Moreover, isomer analysis of LAOOH and SQOOH indicated that LA and SQ are oxidized in sebum by discrete oxidation mechanisms (LA oxidized by free radical oxidation, whereas SQ oxidized by singlet oxygen oxidation). Such results may further lead to the development of mechanism-specific ways to prevent oxidation of sebum via a selection of appropriate antioxidants, ultimately leading to the promotion of skin health.
先前的研究表明，皮脂中的角鲨烯（SQ）通过光氧化机制（即单线态氧氧化）被氧化为角鲨烯氢过氧化物（SQOOH），这种化合物会导致皮肤出现不良状况。然而，皮脂中其他脂质（如亚油酸（LA））的氧化尚未得到充分理解。阐明它们的氧化过程，尤其是其机制，可能有助于进一步了解皮脂氧化与皮肤状况之间的关系。在这项研究中，我们使用 HPLC-MS/MS 旨在直接从皮脂中检测 LA 氢过氧化物（LAOOH），并通过分析 LAOOH 的异构体来确定 LA 在皮脂中的氧化机制。我们开发了提取和 HPLC-MS/MS 分析条件，可以充分定量皮脂中的每种 LAOOH 异构体。使用该方法，在健康个体的样本中检测到了 LAOOH，证明了 LAOOH 存在于人皮脂中。此外，LAOOH 和 SQOOH 的异构体分析表明，LA 和 SQ 在皮脂中通过不同的氧化机制被氧化（LA 通过自由基氧化被氧化，而 SQ 通过单线态氧氧化被氧化）。这些结果可能进一步导致开发针对特定机制的方法，通过选择合适的抗氧化剂来防止皮脂氧化，最终促进皮肤健康。
