Linoleic acid and squalene are oxidized by discrete oxidation mechanisms in human sebum. Issue 1 (31st May 2021)

• Record Type: Journal Article
• Authors: Ishikawa, Ayano; Ito, Junya; Shimizu, Naoki; Kato, Shunji; Kobayashi, Eri; Ohnari, Hiroki; Sakata, Osamu; Naru, Eiji; Nakagawa, Kiyotaka
• Is Part Of: Annals of the New York Academy of Sciences. Volume 1500:Issue 1(2021)
• Page Start: 112
• Page End: 121
• Publication Date: 2021-05-31
• Subjects: sebum -- lipid oxidation mechanisms -- linoleic acid hydroperoxide -- squalene hydroperoxide -- HPLC–MS/MS; Medical sciences -- Periodicals; Medicine -- Periodicals; Science -- Periodicals; 610
• DOI: 10.1111/nyas.14615
• Languages: English
• ISSNs: 0077-8923

Abstract

Abstract: 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. Abstract : In this paper, we developed solid‐phase extraction and HPLC–MS/MS analysis conditions to quantitatively analyze LAOOH in human sebum. Using this method, LAOOH isomers in the sebum of healthy individuals were analyzed. As a result, we succeeded in directly detecting LAOOH from human sebum in addition to SQOOH, which has been previously analyzed. Furthermore, on the basis of the analysis of the structural isomers of LAOOH and SQOOH, it was inferred that LA and SQ are oxidized in sebum by discrete mechanisms.